外文翻译原文
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外文文献翻译译稿1卡尔曼滤波的一个典型实例是从一组有限的,包含噪声的,通过对物体位置的观察序列(可能有偏差)预测出物体的位置的坐标及速度。
在很多工程应用(如雷达、计算机视觉)中都可以找到它的身影。
同时,卡尔曼滤波也是控制理论以及控制系统工程中的一个重要课题。
例如,对于雷达来说,人们感兴趣的是其能够跟踪目标。
但目标的位置、速度、加速度的测量值往往在任何时候都有噪声。
卡尔曼滤波利用目标的动态信息,设法去掉噪声的影响,得到一个关于目标位置的好的估计。
这个估计可以是对当前目标位置的估计(滤波),也可以是对于将来位置的估计(预测),也可以是对过去位置的估计(插值或平滑)。
命名[编辑]这种滤波方法以它的发明者鲁道夫.E.卡尔曼(Rudolph E. Kalman)命名,但是根据文献可知实际上Peter Swerling在更早之前就提出了一种类似的算法。
斯坦利。
施密特(Stanley Schmidt)首次实现了卡尔曼滤波器。
卡尔曼在NASA埃姆斯研究中心访问时,发现他的方法对于解决阿波罗计划的轨道预测很有用,后来阿波罗飞船的导航电脑便使用了这种滤波器。
关于这种滤波器的论文由Swerling(1958)、Kalman (1960)与Kalman and Bucy(1961)发表。
目前,卡尔曼滤波已经有很多不同的实现。
卡尔曼最初提出的形式现在一般称为简单卡尔曼滤波器。
除此以外,还有施密特扩展滤波器、信息滤波器以及很多Bierman, Thornton开发的平方根滤波器的变种。
也许最常见的卡尔曼滤波器是锁相环,它在收音机、计算机和几乎任何视频或通讯设备中广泛存在。
以下的讨论需要线性代数以及概率论的一般知识。
卡尔曼滤波建立在线性代数和隐马尔可夫模型(hidden Markov model)上。
其基本动态系统可以用一个马尔可夫链表示,该马尔可夫链建立在一个被高斯噪声(即正态分布的噪声)干扰的线性算子上的。
系统的状态可以用一个元素为实数的向量表示。
译文交通拥堵和城市交通系统的可持续发展摘要:城市化和机动化的快速增长,通常有助于城市交通系统的发展,是经济性,环境性和社会可持续性的体现,但其结果是交通量无情增加,导致交通拥挤。
道路拥挤定价已经提出了很多次,作为一个经济措施缓解城市交通拥挤,但还没有见过在实践中广泛使用,因为道路收费的一些潜在的影响仍然不明。
本文首先回顾可持续运输系统的概念,它应该满足集体经济发展,环境保护和社会正义的目标.然后,根据可持续交通系统的特点,使拥挤收费能够促进经济增长,环境保护和社会正义。
研究结果表明,交通拥堵收费是一个切实有效的方式,可以促进城市交通系统的可持续发展。
一、介绍城市交通是一个在世界各地的大城市迫切关注的话题。
随着中国的城市化和机动化的快速发展,交通拥堵已成为一个越来越严重的问题,造成较大的时间延迟,增加能源消耗和空气污染,减少了道路网络的可靠性.在许多城市,交通挤塞情况被看作是经济发展的障碍.我们可以使用多种方法来解决交通挤塞,包括新的基础设施建设,改善基础设施的维护和操作,并利用现有的基础设施,通过需求管理策略,包括定价机制,更有效地减少运输密度.交通拥堵收费在很久以前就已提出,作为一种有效的措施,来缓解的交通挤塞情况。
交通拥堵收费的原则与目标是通过对选择在高峰拥挤时段的设施的使用实施附加收费,以纾缓拥堵情况.转移非高峰期一些出行路线,远离拥挤的设施或高占用车辆,或完全阻止一些出行,交通拥堵收费计划将在节省时间和降低经营成本的基础上,改善空气中的质量,减少能源消耗和改善过境生产力。
此计划在世界很多国家和地方都有成功的应用。
继在20世纪70年代初和80年代中期挪威与新加坡实行收费环,在2003年2月伦敦金融城推出了面积收费;直至现在,它都是已经开始实施拥挤收费的大都市圈中一个最知名的例子。
然而,交通拥堵收费由于理论和政治的原因未能在实践中广泛使用。
道路收费的一些潜在的影响尚不清楚,和城市发展的拥塞定价可持续性,需要进一步研究。
Pyrolysis of oil sludge first by thermogravimetry/mass spectroscopy (TG/MS) and then in a horizontal quartz reactor with an electrical laboratory furnace under different pyrolysis conditions was carried out. The influence of heating rate from 5 to 20 °Camin-1, final pyrolysis temperature from 400 to 700 °C, various interval holding stage, and catalyst on the products were investigated in detail. The TG/MS results show that pyrolysis reaction of oil sludge starts at a low temperature of about 200 °C, and the maximum evolution rate is observed between the temperatures of 350-500 °C. A higher final pyrolysis temperature, an interval holding stage, and adding catalyst can promote the pyrolysis conversion (in terms of less solid residue production). In all parameters, an interval holding stage for 20 min near the peak temperature of 400 °C can enhance the yield of oil and improve its quality. Three additives used in this work as catalysts do not improve oil product quality markedly in spite of increasing pyrolysis conversion greatly.油泥的裂解首先通过热重/质谱分析(TG / MS),然后在水平石英反应器中具有不同热解条件下的电气实验室炉进行。
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Vol.25 No.2 PANG Chaoming et al: Methods of Modifying the Brittle (156)DOI 10.1007/s11595-010-1156-yMethods of Modifying the Brittle Behavior ofCementitious CompositesPANG Chaoming1, SUN Wei1, LEUNG Christopher KY2(1.College of Materials Science and Engineering, Southeast University, Jiangsu Key laboratory of Construction Materials, Nanjing 211189,China;2. Department of Civil and Environmental Engineering, Hong Kong University of Science and Technology, Hong Kong, China SAR)Abstract: We put forward effective methods of increasing the tensile strain of cementitiouscomposites with 2% PVA fiber and high fly ash content. The test results show that curing condition hasa significantly effect on the tensile performance. It is approved that the specimens incorporated ap-propriate volume fraction rubber powder and lightweight aggregate greatly increase the tensile strain ofcomposites at medium-term age, but indefinitely at long-term age. To a certain extent, EVA can limitedlyenhance the tensile performance of comentitious composites owing to the formation of polymer membraneand the hindered hydration of cement.Key word: high-ductility cementitious composites (HDCC); tensile properties; high content offly ash; rubber powder; light aggregate; ethylene vinyl alcohol latex powder1 IntroductionCementitious composites are widely used as the majority of structural materials. However, cementitious composites are limited to some special projects due to the inherently brittle behavior. Most efforts have been made to modify the brittle behavior of cementitious composites all along. As a result, the fiber reinforced cementitious composites (FRCC) occurred. In comparison to plain concrete, FRC usually deteriorates the tensile or bending properties by the formation of several cracks and a main crack. In the past two decades, Li, Leung and Wu etc[1-3] investigated the bridging stress of fiber and proposed the theory for high-ductility cementitious composites (here-after abbreviated as HDCCs) or pseudo ductility cemen-titious composites or pseudo strain hardening cementi-tious composites, based on the two nondimensionalized parameters energy absorption rate and normalized flaw size. It has been demonstrated that the ductility behaviors of brittle materials can be achieved by multiple cracks in steady state along the length of the specimen and behave pseudo strain hardening (abbr. PSH). Hereafter, the theories for PSH in the cementitious composites were gradually developed by Li and his co-workers, and the particular theory for “composite design”, based on the micro mechanics parameter, by emphasizing the proper integrant materials and interface was proposed[4,5]. The cementitious composite with high tensile strain capacity of 3%-6%, whose strain capacity is far outperforming conventional cementitious composites, was achieved[6].Recently increasing researchers are interesting to the new type of fiber reinforced cementitious composite. However, it is not easy to achieve PSH in discontinuous random fiber reinforced. Strain due to a little deviation of raw materials occur even if the well-known same mixture proportion of ECC is used due to a little deviation of raw materials. Meanwhile, the design method of existing theory depend on known experimental micro mechanics parameters, such as the fracture toughness, fiber content, fiber strength, fiber distribution, the bridging stress and interface properties between fiber matrix, etc. Moreover, it is very difficult to achieve the accurate fiber distribu-tion and bridging stress due to the randomization and inhomogeneity of the distribution of fiber in composites. But the micromechanical parameters and the ductile be-havior is strongly affected by the bridging stress governed by fiber debonding, fiber bending, fiber rupture, matrix spalling and their coupling[2].The focus in the current study is to discover the ef-ficacious methods to increase the tensile strain of HDCC. It is well know that curing conditions have a significantly©Wuhan University of Technology and Springer-Verlag Berlin Heidelberg 2010 (Received: Jan. 6, 2009; Accepted: Oct. 16, 2009)PANG Chaoming(庞超明): Ph D candidate; E-mail: pangchao@seu. edu. cnJournal of Wuhan University of Technology-Mater. Sci. Ed. Feb.2010157conditions were used for comparison, considering that the structures in practice project are often exposed to different environment and different curing condition are usually applied according to the lab environment in the different researches. For the brittle cementitious com-posites, the matrix cracking strength, which is determined by the matrix toughness and the largest crack or flaw in the stress section of specimen provided that the matrix cracking is controlled by fracture process, does not de-crease unlimitedly but reaches a lower bound at steady state cracking stress with the growing flaw size [7]. Moreover, the discontinuous pre-existing flaw or mi-cro-voids may relax the crack-tip stress triaxiality, dif-fuse the intensity of crack-tip stress singularity and consume more energy. To ensure the formation of multiple cracks, it is desirable to introduce a rtificial flaws in the matrix to reduce its crack tip toughness and increase the crack size due to energy absorption of flaw [8]. Therefore, different materials, such as rubber powder and fine lightweight aggregate, were added to the composites to increase the strain capacity.2 ExperimentalSpecial green island brand P·II 52.5 cement was used. The range of particle size of fly ash is mainly 2-10 μm, and the active index of compressive strength at 7 days, 28 days and 90 days are the 86%, 84% and 96% respectively followed by ASTM C311-04. Polyvinyl alcohol fiber (abbr. PVAF) produced by Japan Kuraray Limited Corporation was used, and its density, length, diameter were 1.3 g/cm 3, 12 mm, 38 μm respectively,also its elastic modulus and rate of elongation is 33 GPaand 6.5% respectively.The particle size of silica fume, silica filler and silica sand used is 1-20 μm, 1-15 μm and 50-200 μm respec-tively. ADVA105 superplastics admixture (abbr. Sp) was %produced by Grace Co.LTD and its solid content is 23. SP4000 (abbr. SP4), which is ethylene vinyl alcohol (abbr. EVA) latex powder and is produced by Japan Kuraray Trading Co.LTD, was used in this study. The particle size of lightweight aggregate (abbr. LA) is between 1 mm and 3 mm, whose specific density is 1 500 kg/m 3, and the loose volume weight is about 780 kg/m 3. Rubber pow-der with the particle size of 0.4 mm was also used.The specimen was demoulded 24 hours after casting, where the temperature and relative humidity was about 20±2 ℃ and (60±5)% respectively, then cured in water at curing room , where the temperature is 27 ℃ (ac-cording to the BS standard). The nominal sizes used for tensile performance and compressive performance are about 350×50×15 mm and 40×40×40 mm respec-tively. The dimensions of the specimen were accurately measured by vernier caliper and all the specimens were polished to smooth surface before testing to obtain ac-curate experimental results, and at least three specimens were tested at each age.The tensile performance was tested under the dis-placement control in the MTS810-25 kN materials test-ing system with the displacement rate of 0.15 mm/min. Linear variable displacement transducer was used to measure the displacement at the gage length of 150 mm for the more accuracy purpose. The first crack strain εfc , the peak strain εp and the maximum strain εm repre-sent to the strain corresponding to the first crack stress σTc when the first crack occurred, peak stress σTp when the stress reaches the peak, and the strain when the stress descends up to 90% σTp , respectively.3 Results3.1 Effect of curing conditions on me-chanical properties of HDCCAccording to previous work, two mix proportions shown in Table 1 were used, i e , SP4 and W1 with high volume fraction fly ash and low ratio of water to binder (cement and fly ash). Table 1 Mix proportion in mass of HDCC No. cement FA SP4 sand water Sp PVAF SP4 1 3.9 0.1 1.0 1.1 0.022 0.090 W1 1 4.0 0 1.0 1.0 0.023 0.096For the purpose of comparing the effect of different curing condition on the tensile performance, four types of curing conditions were applied in mixture SP4 as fol-lowing: full dry curing in room temperature condition after demoulded, which corresponds to symbol D in the denominated title in Table 2, dry curing in room tem-perature condition after 3-day curing in water corre-sponding to symbol W3D, dry curing in room tempera-ture condition after 7-day water curing corresponding to symbol W7D, and 28-day water curing corresponding to symbol W. The only two types of curing conditions wereused in mixture W1: dry curing in room temperature condition after 7 days water curing and full water curing. Table 2 list the test results of the tensile strength and strain and compressive strength on different curing con-ditions at the age of 7-day and 28-day.Vol.25 No.2 PANG Chaoming et al : Methods of Modifying the Brittle …1583.2 Effect of rubber powder on mechanic-al properties of HDCCThe specimen without rubber powder is regarded as control specimen, and two mixtures of HDCCs with the rubber powder were prepared. SR7 and SR11 represent for HDCC of the volume fraction of 7% and 11%, re-spectively. For estimating the long-term performance, the accelerated curing method was conducted, that is, after cured in water for 7 days, at least three specimens were put to the heat curing room for 72 hours, where the temperature and relative humidity are 80 ℃%and 95respectively, the mechanical performance was measured after being cooled down in the room temperature condi-tion. The mix proportion used and test results are sum-marized in Table 3, Table 4 respectively. Heat curing corresponds to symbol HC. Fig.1 shows the tensile stress versus strain curves of SR7 and SR11 at 28 days.3.3 Effect of lightweight aggregate onmechanical properties of HDCC For the purpose of researching the effect of light-weight aggregate on the tensile strain of HDCC with highflyash content, the volume fraction of 3.5% was incor-porated into the mixture, and the mix proportion was listed in Table 5. The specimen FA3 and FA3LA corre-spond to control specimen and specimen with lightweight aggregate, respectively.The test results are shown in Table 6. The condition of heat curing is the same as mentioned above. Fig.2(a) and Fig.2(b) showed the typical stress vs strain curve of FA3 and FA3LA3.5 at different age: 7 days, 28 days and heat curing 3 days.Table 2 Test results of HDCC on different curing conditionsSP4D SP4W3D SP4W7D SP4W W1 7-day 28-day 7-day 28-day 28-day 90-day 7-day 28-day W7 W28 W7DσTfc /MPa 2.68 2.36 2.91 2.54 3.26 3.28 2.70 3.36 2.76 3.65 3.62 εfc /% 0.080 0.069 0.075 0.096 0.080 0.089 0.119 0.060 0.088 0.047 0.128 σTp /MPa 3.30 3.39 3.76 3.14 4.07 3.62 3.17 4.02 3.27 3.81 4.69εp /% 1.53 3.95 2.69 2.56 2.82 2.58 2.78 0.77 1.050.35 2.94 εm /% 1.69 4.28 2.80 2.79 3.54 2.66 2.97 1.81 1.360.54 3.39 σcom /MPa 22.8 27.2 — — — — 23.4 36.0 35.8 58.9 — Table 3 Mix proportion in mass of HDCC with different volume fraction of rubber powder No. Cement FA Filler Sand Rubber Water Sp PVAFControl 1 1.50 0.25 1.00 0 0.63 0.015 0.057 SR7 1 1.50 0.25 0.65 0.163 0.58 0.020 0.055 SR11 1 1.50 0.25 0.40 0.263 0.58 0.020 0.055 Table 4 Test results of HDCCs with different volume fraction of rubber powderControl SR7 SR117-day 28-day 90-day 7-day 28-day HC 7-day 28-day HCσTfc /MPa 3.58 4.61 3.81 2.31 2.60 3.63 2.19 2.31 3.28 εfc /% 0.050 0.042 0.027 0.036 0.022 0.039 0.034 0.051 0.041 σTp/MPa 4.30 5.05 4.53 2.49 3.00 3.81 2.72 3.18 3.57 εp /% 1.33 0.84 0.29 0.31 0.58 0.16 1.04 2.15 0.20 εm/% 1.59 0.98 0.39 0.54 1.07 0.71 1.40 2.49 0.34 σcom /MPa 49.6 66.2 — 29.7 35.7 40.5 24.8 31.4 37.0 Table 5 Mix proportion in mass No. Cement FA LA Sand Water Sp PVAF FA3 1 3 — 1 1 0.025 0.056 FA3LA 1 3 0.16 1 1 0.028 0.056 Table 6 Test results of HDCCs with or without lightweightaggregate FA3 FA3LA 7 d 28 d 90 d HC 7 d 28 d 90 d HCσTfc /MPa 1.42 2.68 3.60 4.38 2.86 3.15 3.25 6.42εfc /% 0.015 0.044 0.031 0.022 0.025 0.045 0.040 0.037 σTp /MPa 2.91 3.46 4.86 4.86 2.86 3.91 3.92 6.49εp /% 0.04 0.58 0.29 0.08 0.03 1.96 0.23 0.04 εm /% 1.16 0.96 0.66 0.31 1.40 2.07 0.54 0.38 σcom/MPa 21.5 44.7 69.5— 19.0 44.2 74.8 —Journal of Wuhan University of Technology-Mater. Sci. Ed. Feb.20101593.4 Effect of EVA powder on mechanicalproperties of HDCCA series of HDCCs specimens with or without EVA powder were also prepared, cured and tested at prescribed age followed by the test procedure. The condition of heat curing is also the same as mentioned above. The mix proportion used is listed in Table 7, and test results of tensile properties are presented in Table 8 and Fig.2(c) respectively. S is the control specimen, and SS4 is representative for HDCC with EVA powder.4 Discussion It can be concluded that the curing conditions have a great effect on the tensile properties from Table 1 and Table 2. The tensile properties exhibit a great difference at 28 days due to different curing condition for mixture SP4 and mixture W1. The HDCC cured in water per-forms better than that in room temperature condition atthe early age, however, as the age increases, the tensileperformance of HDCCs cured in room temperature condition shows an increasing tendency while that curedin the water decreases. The tensile strain of specimensthat of W3D is similar to that of W7D at 28 days, whichtest results also show the ultimate tensile strength has not direct relationship with the tensile strain, and high tensile strain do not mean low tensile strength, and vice versa . That can be explained as follows: curing condi-tion plays a significant influence on microstructure and macroscopical performance of cementitious composites. For fiber reinforced cementitious composites, there exists a distinctive layer of interface zone about 30-50 μm away from the fiber surface [9]. Also the interface will strongly influence the toughness of the compositesand frictional bond [10]. Generally the interface zone is considerable weaker than the matrix due to the large calcium hydroxide crystals and higher porosity for the FRCCs with steel fiber or polypropylene fiber [9], but thePVA fiber is a special organic fiber to the cementitiouscomposites. The majority of fibers used to the cementi-tious composites, such as steel fiber, polypropylenefiber,etc , will not react with the hydration products of cement, but the investigations by Akers show that [11], the PVA fiber performs surprisingly high chemical bonding between the PVA fiber and cement hydrationproducts due to the strong hydrophilic characteristic or hydrogen intermolecular bond induced by the hydroxyl groups, and as the age increase, while there are no evi-dent change in fiber properties, the bonding strengthbetween fiber and cement-based matrix will increase due to an increase in interface bond with age. The re-searches by Kanda T etc also shows that the apparent chemical bonding between PVA fiber and cement ma-,trix independent of the water-to cement ratio of matrix, is relatively stable and up to 30-40 MPa, but the value of friction bond, affected by water to cement ratio, is be-tween 2.2 MPa to 4.4 MPa when the water to cementvaries from 0.62 to 0.27[12]. Through the investigation by Li and his co-workers [3], only the FRCC with the appropriate fracture toughness of matrix and frictional Table 7 Mix proportion with or without EVA in mass No. Cement FA SF SP4 Sand Water Sp PVAF S 1 3.85 0.1 — 1 1.21 0.033 0.096 SS4 1 3.60 0.1 0.1 1 1.21 0.032 0.096 Table 8 Test results of HDCCs with or without EVAS SS47 d 28 d HC 7 d 28 d HCσTfc /MPa 1.15 3.32 4.37 1.86 3.14 3.89 εfc/% 0.021 0.067 0.029 0.057 0.086 0.049 σTp /MPa 1.94 3.43 4.90 2.03 3.42 4.75 εp /% 0.20 1.18 0.33 0.49 1.24 0.60εm /% 0.54 1.63 0.40 1.55 1.73 0.74 σcom /MPa 13.0 33.5 — 13.0 35.4 — (a) FA3 (b) FA3LA (c) S and SS4Fig.2 Stresses vs. Strain curves of FA3, FA3LA, S and SS4 at different ageVol.25 No.2 PANG Chaoming et al: Methods of Modifying the Brittle (160)and high strain capacity of FRCC can dominantly be achieved by using PVA fiber, and the interfacial fric-tional stress for FRCC with PSH behavior show the relative definite requirement and shall preferably be between 0.8 to 2.0 MPa[13], and the value can be achieved by applying oil agent[14]. In the present study, the PVA fiber, which had been coated with the oiling agent by Japan Kuraray Co. LTD, was employed. Ow-ing to low water to binder ratio and high content of fly ash (W/B=0.20, FA/C=4.0), and the specimens were kept only for 0-7 days in water and then longer than 20 days cured in room temperature condition, where there is no enough water for cement hydration, therefore they exhibit relative lower hydration degree and larger shrinkage than those cured in the water in all time. The lower hydration degree and larger shrinkage result in relatively lower frictional bond and weaker interface between PVA fiber and matrix[15]. Therefore, the former forms relatively looser structure and satisfies the re-quirement of low interfacial frictional stress, therefore performs better in strain hardening. Also the failure pat-tern of fiber rupture can be observed in testing process of the latter.In general, the definite range of interfacial fric-tional stress for achieving PSH behavior of FRCC, lower ratio of cement to binder, high fly ash content and PVA fiber properties contribute to the effect of curing condition on the tensile behavior.It can be deduced from Table 4, Table 6, Fig.1 and Fig.2 that the tensile strength of HDCC with rubber powder or light aggregate keep on growing, while the tensile strain also increases as the age increases from 7 days to 28 days, then decreased as the age continually grows up to 90 days or when heat curing was applied. That is because the fiber/matrix bond strength should saturate in a duration of less than 14-28 days, and ma-ture much earlier than matrix properties in cementi-tious[16]. But the high content of fly ash will considera-bly lower the chemical bond and delay the mature due to diluting the metal cation concentration on the fiber surface at early age and as a result the strain increases from 7 days to 28 days[17]. But the friction strength and the facture toughness of matrix continue to develop as age increase to 28 days as the second hydration of fly ash continually develop due to activity effect of fly ash under high temperature or at long age. When the imbal-ance of develop rate occurs, the strain decreases with the continual increasing age.From Table 4 and Table 6, not all the specimens show better tensile performance than the control specimen, only the tensile strain of the specimens with 11% volume fraction rubber powder or 3.5% light-weight aggregate increase comparing to the control specimen at 28 days. The specimens FA3 and FA3LA rapidly reach ultimate strength then crack, and only few cracks develop due to the high fracture toughness of matrix and the low friction between matrix and PVA fiber at 7 days, but the specimen can still maintain the considerable strain after cracking owing to fiber gradu-ally being pulled out. And the SR7 also shows the similar tendency at 28 days. It is possible that the frac-ture toughness of matrix develops faster than the chemical bond and the frictional bond due to the low ratio of water to binder and high content fly ash. However, the specimen with the 11% volume fraction rubber pow-der reaches 2.15% in comparison with only 0.84% for the corresponding control specimen and the ultimate strain of with or without lightweight aggregate varies from 1.96% to 0.58%. The similar test results, i e, pre-existing flaw or micro-voids can modify the brittle behavior of HDCC, were observed in the reference[8] as the pre-existing flaw can relax the crack-tip triaxiality, diffuse the intensity of crack-tip stress and consume more energy, and the lager flaw will not influence the cracking strength but reached a lower bound at a steady state of cracking stress.Table 8 and Fig.2 present that the EVA latex powder show a little positive effect on the tensile strain at different age. It is possible that the EVA as a polymer can form a layer polymer membrane, which hinders the hydration of cementitious materials, but the membrane only influences a little hydration process owing to the lower content, about 1% volume fraction, in compos-ites.In summary, the appropriate fracture toughness of matrix and frictional bond between fiber and matrix is necessary conditions to achieve the PSH behavior or high strain capability. The curing condition emphasize particularly on the influence of friction bond, but the incorporation of rubber powder and lightweight lay particular stress on the fracture toughness of matrix. However the incorporation of rubber powder and lightweight aggregate lower the fracture toughness of matrix and facilitate the crack of matrix, which will possibly lower the effect of curing condition on the tensile properties.Journal of Wuhan University of Technology-Mater. Sci. Ed. Feb.2010 1615 ConclusionsSome methods to modifying the brittle behavior of HDCC with high content fly ash are proposed. It is undoubted that curing condition will strongly influence the microstructure of cementitious composites. The test results show that curing condition has a significant ef-fect on the tensile strain of HDCC with high content fly ash, and dry curing condition will show the clear trend to increase the tensile strain of HDCC with high content fly ash. Not all the specimens but the specimens with appropriate volume fracture rubber powder and light-weight aggregate greatly enhance the tensile strain of HDCC at medium-term age, but indefinitely at long-term age impossibly because disconnected pre-existing flaw or micro-voids may relax the crack-tip, diffuse the intensity of crack-tip stress and significantly consume energy. To a certain extent, EVA can enhance the tensile performance of HDCC owing to the hindered hydration of cement based materials as a result of the formation of polymer membrane. But it is possible that the incorporation of rubber powder and lightweight will lower the effect of curing condition on the tensile per-formance.It also experimentally demonstrates that some specimens rapidly reach ultimate strength and crack, but some specimen can still maintain the considerable strain after cracking owing to fiber gradually being pulled out. The tensile stress keeps increasing, but the tensile strain firstly increases then decreases as the age continually grows because of the imbalance of develop rate between bond strength and matrix properties. References[1]LI V C and LEUNG C K Y. Steady-state and MultipleCracking of Short Random Fiber Composites[J]. Journal ofEngineering Mechanics, 1992, 118(11): 2 246-2 264[2]LEUNG C K Y and LI V C. Effect of Fiber Inclination onCrack Bridging Stress in Fiber Reinforced Brittle MatrixComposites[J]. Journal of Mechanical Physics, 1992, 40(6):1 333-1 362[3]LI V C and WU H C. Conditions for PseudoStrain-Hardening in Fiber Reinforced Brittle MatrixComposites[J]. Applied Mechanics Revolution, 1992, 45(8):390-398[4]LI V C, MISHRA D K and WU H C. Matrix Design forPseudo-Strain-Hardening Fiber Reinforced CementitiousComposites[J]. Materials and Structures, 1995, 28: 586-595 [5]KANDA T, LI V C and Member of ASCE. New Micro-mechanics Design Theory for Pseudostrain Hardness Ce-mentitious Composite[J]. Journal of Engineering Me-chanics, 1999, 125(4): 373-381[6]LI V C, WANG S and WU C. Tensile Strain- HardeningBehavior or Polyvinyl Alcohol Engineered CementitiousComposite (PVA-ECC)[J]. ACI Materials Journal, 2001,98(6): 483-492[7]MAESHALL D B, COX B N and EVANS A G. The Mechan-ics of Matrix Cracking in Brittle Matrix Fiber Composites[J].ACTA Metallurgical, 1985, 33(11): 2 013-2 021[8]WANG S and LI V C. Tailoring of Pre-Existing Flaw inECC Matrix for Saturated Strain Hardening[C]. Proceed-ings of the Fifth International Conference on FractureMechanics of Concrete and Concrete Structures. Colorado:Ia-FraMCos, 2004: 1 005-1 012[9]Li V C, WU H C, and CHAN Y W. Interfacial PropertyTailoring for Pseudo Strain-Hardening Cementitious Composites[C]. Advanced Technology on Design and Fabrication of Composite Materials and Structures. Neth-erlands: Kluwer Acad. Publ., 1995: 261-268[10]SUN W, MANDEL J A and SAID Samir. Studies of theProperties of the Fiber-Matrix Interface in Steel Fiber Re-inforced Mortar[J]. ACI Materials Journal, 1987, 84(12):101-109[11]AKERS S A S. Long Term Durability of PVA ReinforcingFibers in a Cement Matrix[J]. The International Journal ofCement Composite and Lightweight Concrete, 1989, 11:79-91[12]KANDA T and LI V C. Interface Property and ApparentStrength of High-Strength Hydrophilic Fiber in CementMatrix[J]. Journal of Materials in Civil Engineering, 1998,10(1): 5-13[13]LI V C and WANG S. Process for Increasing the Ductilityof High Performance Fiber-Reinforced Brittle Matrix Composites and Composites Produced Thereby[P]. US Patent 7169224. 2007-01-30[14]REDON C. Measuring and Modifying Interface Propertiesof PVA Fibers in ECC Matrix[J]. ASCE J. Materials inCivil Engineering, 2001, 13(6): 399-406[15]CHEN H SUN W and PIET S. Interfacial Transition ZoneBetween Aggregate and Paste in Cementitious Composites(II): Mechanism of Formation and Degradation of Interfa-cial Transition Zone Microstructure and Its Influence Factors[J].Journal of the Cement Ceramic Society, 2004, 32(1): 70-80 [16]CHAN Y W and LI V C. Age Effect on the Characteristicsof Fibre/Cement Interfacial Properties[J]. Journal of Ma-terials Science, 1997, 32: 5 287-5 292[17]WANG S and LI V C. Engineered Cementitious Compos-ites with High-Volume Fly Ash[J]. ACI Materials Journal,2007, 104(3): 233-241。
外文原文(一)Savigny and his Anglo-American Disciple s*M. H. HoeflichFriedrich Carl von Savigny, nobleman, law reformer, champion of the revived German professoriate, and founder of the Historical School of jurisprudence, not only helped to revolutionize the study of law and legal institutions in Germany and in other civil law countries, but also exercised a profound influence on many of the most creative jurists and legal scholars in England and the United States. Nevertheless, tracing the influence of an individual is always a difficult task. It is especially difficult as regards Savigny and the approach to law and legal sources propounded by the Historical School. This difficulty arises, in part, because Savigny was not alone in adopting this approach. Hugo, for instance, espoused quite similar ideas in Germany; George Long echoed many of these concepts in England during the 1850s, and, of course, Sir Henry Sumner Maine also espoused many of these same concepts central to historical jurisprudence in England in the 1860s and 1870s. Thus, when one looks at the doctrinal writings of British and American jurists and legal scholars in the period before 1875, it is often impossible to say with any certainty that a particular idea which sounds very much the sort of thing that might, indeed, have been derived from Savigny's works, was, in fact, so derived. It is possible, nevertheless, to trace much of the influence of Savigny and his legal writings in the United States and in Great Britain during this period with some certainty because so great was his fame and so great was the respect accorded to his published work that explicit references to him and to his work abound in the doctrinal writing of this period, as well as in actual law cases in the courts. Thus, Max Gutzwiller, in his classic study Der einfluss Savignys auf die Entwicklung des International privatrechts, was able to show how Savigny's ideas on conflict of laws influenced such English and American scholars as Story, Phillimore, Burge, and Dicey. Similarly, Andreas Schwarz, in his "Einflusse Deutscher Zivilistik im Auslande," briefly sketched Savigny's influence upon John Austin, Frederick Pollock, and James Bryce. In this article I wish to examine Savigny's influence over a broader spectrum and to draw a picture of his general fame and reputation both in Britain and in the United States as the leading Romanist, legal historian, and German legal academic of his day. The picture of this Anglo-American respect accorded to Savigny and the historical school of jurisprudence which emerges from these sources is fascinating. It sheds light not only upon Savigny’s trans-channel, trans-Atlantic fame, but also upon the extraordinarily*M.H.Hoeflich, Savigny and his Anglo-American Disciples, American Journal of Comparative Law, vol.37, No.1, 1989.cosmopolitan outlook of many of the leading American and English jurists of the time. Of course, when one sets out to trace the influence of a particular individual and his work, it is necessary to demonstrate, if possible, precisely how knowledge of the man and his work was transmitted. In the case of Savigny and his work on Roman law and ideas of historical jurisprudence, there were three principal modes of transmission. First, there was the direct influence he exercised through his contacts with American lawyers and scholars. Second, there was the influence he exercised through his books. Third, there was the influence he exerted indirectly through intermediate scholars and their works. Let us examine each mode separately.I.INFLUENCE OF THE TRANSLATED WORKSWhile American and British interest in German legal scholarship was high in the antebellum period, the number of American and English jurists who could read German fluently was relatively low. Even those who borrowed from the Germans, for instance, Joseph Story, most often had to depend upon translations. It is thus quite important that Savigny’s works were amongst the most frequently translated into English, both in the United States and in Great Britain. His most influential early work, the Vom Beruf unserer Zeitfur Rechtsgeschichte und Gestzgebung, was translated into English by Abraham Hayward and published in London in 1831. Two years earlier the first volume of his History of Roman Law in the Middle Ages was translated by Cathcart and published in Edinburgh. In 1830, as well, a French translation was published at Paris. Sir Erskine Perry's translation of Savigny's Treatise on Possession was published in London in 1848. This was followed by Archibald Brown's epitome of the treatise on possession in 1872 and Rattigan's translation of the second volume of the System as Jural Relations or the Law of Persons in 1884. Guthrie published a translation of the seventh volume of the System as Private International Law at Edinburgh in 1869. Indeed, two English translations were even published in the far flung corners of the British Raj. A translation of the first volume of the System was published by William Holloway at Madras in 1867 and the volume on possession was translated by Kelleher and published at Calcutta in 1888. Thus, the determined English-speaking scholar had ample access to Savigny's works throughout the nineteenth century.Equally important for the dissemination of Savigny's ideas were those books and articles published in English that explained and analyzed his works. A number of these must have played an important role in this process. One of the earliest of these is John Reddie's Historical Notices of the Roman law and of the Progress of its Study in Germany, published at Edinburgh in 1826. Reddie was a noted Scots jurist and held the Gottingen J.U.D. The book, significantly, is dedicated to Gustav Hugo. It is of that genre known as an external history of Roman law-not so much a history of substantive Roman legal doctrine but rather a historyof Roman legal institutions and of the study of Roman law from antiquity through the nineteenth century. It is very much a polemic for the study of Roman law and for the Historical School. It imparts to the reader the excitement of Savigny and his followers about the study of law historically and it is clear that no reader of the work could possibly be left unmoved. It is, in short, the first work of public relations in English on behalf of Savigny and his ideas.Having mentioned Reddie's promotion of Savigny and the Historical School, it is important to understand the level of excitement with which things Roman and especially Roman law were greeted during this period. Many of the finest American jurists were attracted-to use Peter Stein's term-to Roman and Civil law, but attracted in a way that, at times, seems to have been more enthusiastic than intellectual. Similarly, Roman and Civil law excited much interest in Great Britain, as illustrated by the distinctly Roman influence to be found in the work of John Austin. The attraction of Roman and Civil law can be illustrated and best understood, perhaps, in the context of the publicity and excitement in the English-speaking world surrounding the discovery of the only complete manuscript of the classical Roman jurist Gaius' Institutes in Italy in 1816 by the ancient historian and German consul at Rome, B.G. Niebuhr. Niebuhr, the greatest ancient historian of his time, turned to Savigny for help with the Gaius manuscript (indeed, it was Savigny who recognized the manuscript for what it was) and, almost immediately, the books and journals-not just law journals by any means-were filled with accounts of the discovery, its importance to legal historical studies, and, of course, what it said. For instance, the second volume of the American Jurist contains a long article on the civil law by the scholarly Boston lawyer and classicist, John Pickering. The first quarter of the article is a gushing account of the discovery and first publication of the Gaius manuscript and a paean to Niebuhr and Savigny for their role in this. Similarly, in an article published in the London Law Magazine in 1829 on the civil law, the author contemptuously refers to a certain professor who continued to tell his students that the text of Gaius' Institutes was lost for all time. What could better show his ignorance of all things legal and literary than to be unaware of Niebuhr's great discovery?Another example of this reaction to the discovery of the Gaius palimpsest is to be found in David Irving's Introduction to the Study of the Civil Law. This volume is also more a history of Roman legal scholarship and sources than a study of substantive Roman law. Its pages are filled with references to Savigny's Geschichte and its approach clearly reflects the influence of the Historical School. Indeed, Irving speaks of Savigny's work as "one of the most remarkable productions of the age." He must have been truly impressed with German scholarship and must also have been able to convince the Faculty of Advocates, forwhom he was librarian, of the worth of German scholarship, for in 1820 the Faculty sent him to Gottingen so that he might study their law libraries. Irving devotes several pages of his elementary textbook on Roman law to the praise of the "remarkable" discovery of the Gaius palimpsest. He traces the discovery of the text by Niebuhr and Savigny in language that would have befitted an adventure tale. He elaborates on the various labors required to produce a new edition of the text and was particularly impressed by the use of a then new chemical process to make the under text of the palimpsest visible. He speaks of the reception of the new text as being greeted with "ardor and exultation" strong words for those who spend their lives amidst the "musty tomes" of the Roman law.This excitement over the Verona Gaius is really rather strange. Much of the substance of the Gaius text was already known to legal historians and civil lawyers from its incorporation into Justinian's Institutes and so, from a substantive legal perspective, the find was not crucial. The Gaius did provide new information on Roman procedural rules and it did also provide additional information for those scholars attempting to reconstruct pre-Justinianic Roman law. Nevertheless, these contributions alone seem hardly able to justify the excitement the discovery caused. Instead, I think that the Verona Gaius discovery simply hit a chord in the literary and legal community much the same as did the discovery of the Rosetta Stone or of Schliemann’s Troy. Here was a monument of a great civilization brought newly to light and able to be read for the first time in millenia. And just as the Rosetta Stone helped to establish the modern discipline of Egyptology and Schliemann's discoveries assured the development of classical archaeology as a modern academic discipline, the discovery of the Verona Gaius added to the attraction Roman law held for scholars and for lawyers, even amongst those who were not Romanists by profession. Ancillary to this, the discovery and publication of the Gaius manuscript also added to the fame of the two principals involved in the discovery, Niebuhr and Savigny. What this meant in the English-speaking world is that even those who could not or did not wish to read Savigny's technical works knew of him as one of the discoverers of the Gaius text. This fame itself may well have helped in spreading Savigny's legal and philosophical ideas, for, I would suggest, the Gaius "connection" may well have disposed people to read other of Savigny's writings, unconnected to the Gaius, because they were already familiar with his name.Another example of an English-speaking promoter of Savigny is Luther Stearns Cushing, a noted Boston lawyer who lectured on Roman law at the Harvard Law School in 1848-49 and again in 1851- 1852.Cushing published his lectures at Boston in 1854 under the title An Introduction to the Study of Roman Law. He devoted a full chapter to a description of the historical school and to the controversy betweenSavigny and Thibaut over codification. While Cushing attempted to portray fairly the arguments of both sides, he left no doubt as to his preference for Savigny's approach:The labors of the historical school have established an entirely new and distinct era in the study of the Roman jurisprudence; and though these writers cannot be said to have thrown their predecessors into the shade, it seems to be generally admitted, that almost every branch of the Roman law has received some important modification at their hands, and that a knowledge of their writings, to some extent, at least, is essentially necessary to its acquisition.译文(一)萨维尼和他的英美信徒们*M·H·豪弗里奇弗雷德里奇·卡尔·冯·萨维尼出身贵族,是一位出色的法律改革家,也是一位倡导重建德国教授协会的拥护者,还是历史法学派的创建人之一。
第1页 共19页中文3572字毕业论文(设计)外文翻译标题:危机管理-预防,诊断和干预一、外文原文标题:标题:Crisis management: prevention, diagnosis and Crisis management: prevention, diagnosis andintervention 原文:原文:The Thepremise of this paper is that crises can be managed much more effectively if the company prepares for them. Therefore, the paper shall review some recent crises, theway they were dealt with, and what can be learned from them. Later, we shall deal with the anatomy of a crisis by looking at some symptoms, and lastly discuss the stages of a crisis andrecommend methods for prevention and intervention. Crisis acknowledgmentAlthough many business leaders will acknowledge thatcrises are a given for virtually every business firm, many of these firms do not take productive steps to address crisis situations. As one survey of Chief Executive officers of Fortune 500 companies discovered, 85 percent said that a crisisin business is inevitable, but only 50 percent of these had taken any productive action in preparing a crisis plan(Augustine, 1995). Companies generally go to great lengths to plan their financial growth and success. But when it comes to crisis management, they often fail to think and prepare for those eventualities that may lead to a company’s total failure.Safety violations, plants in need of repairs, union contracts, management succession, and choosing a brand name, etc. can become crises for which many companies fail to be prepared untilit is too late.The tendency, in general, is to look at the company as a perpetual entity that requires plans for growth. Ignoring the probabilities of disaster is not going to eliminate or delay their occurrences. Strategic planning without inclusion ofcrisis management is like sustaining life without guaranteeinglife. One reason so many companies fail to take steps to proactively plan for crisis events, is that they fail to acknowledge the possibility of a disaster occurring. Like an ostrich with its head in the sand, they simply choose to ignorethe situation, with the hope that by not talking about it, it will not come to pass. Hal Walker, a management consultant, points out “that decisions will be more rational and better received, and the crisis will be of shorter duration, forcompanies who prepare a proactive crisis plan” (Maynard, 1993) .It is said that “there are two kinds of crises: those that thatyou manage, and those that manage you” (Augustine, 1995). Proactive planning helps managers to control and resolve a crisis. Ignoring the possibility of a crisis, on the other hand,could lead to the crisis taking a life of its own. In 1979, theThree-Mile Island nuclear power plant experienced a crisis whenwarning signals indicated nuclear reactors were at risk of a meltdown. The system was equipped with a hundred or more different alarms and they all went off. But for those who shouldhave taken the necessary steps to resolve the situation, therewere no planned instructions as to what should be done first. Hence, the crisis was not acknowledged in the beginning and itbecame a chronic event.In June 1997, Nike faced a crisis for which they had no existi existing frame of reference. A new design on the company’s ng frame of reference. A new design on the company’s Summer Hoop line of basketball shoes - with the word air writtenin flaming letters - had sparked a protest by Muslims, who complained the logo resembled the Arabic word for Allah, or God.The council of American-Islamic Relations threatened aa globalNike boycott. Nike apologized, recalled 38,000 pairs of shoes,and discontinued the line (Brindley, 1997). To create the brand,Nike had spent a considerable amount of time and money, but hadnever put together a general framework or policy to deal with such controversies. To their dismay, and financial loss, Nike officials had no choice but to react to the crisis. This incident has definitely signaled to the company that spending a little more time would have prevented the crisis. Nonetheless,it has taught the company a lesson in strategic crisis management planning.In a business organization, symptoms or signals can alert the strategic planners or executives of an eminent crisis. Slipping market share, losing strategic synergy anddiminishing productivity per man hour, as well as trends, issues and developments in the socio-economic, political and competitive environments, can signal crises, the effects of which can be very detrimental. After all, business failures and bankruptcies are not intended. They do not usually happen overnight. They occur more because of the lack of attention to symptoms than any other factor.Stages of a crisisMost crises do not occur suddenly. The signals can usuallybe picked up and the symptoms checked as they emerge. A company determined to address these issues realizes that the real challenge is not just to recognize crises, but to recognize themin a timely fashion (Darling et al., 1996). A crisis can consistof four different and distinct stages (Fink, 1986). The phasesare: prodromal crisis stage, acute crisis stage, chronic crisisstage and crisis resolution stage.Modern organizations are often called “organic” due tothe fact that they are not immune from the elements of their surrounding environments. Very much like a living organism, organizations can be affected by environmental factors both positively and negatively. But today’s successfulorganizations are characterized by the ability to adapt by recognizing important environmental factors, analyzing them, evaluating the impacts and reacting to them. The art of strategic planning (as it relates to crisis management)involves all of the above activities. The right strategy, in general, provides for preventive measures, and treatment or resolution efforts both proactively and reactively. It wouldbe quite appropriate to examine the first three stages of acrisis before taking up the treatment, resolution or intervention stage.Prodromal crisis stageIn the field of medicine, a prodrome is a symptom of the onset of a disease. It gives a warning signal. In business organizations, the warning lights are always blinking. No matter how successful the organization, a number of issues andtrends may concern the business if proper and timely attentionis paid to them. For example, in 1995, Baring Bank, a UK financial institution which had been in existence since 1763,ample opportunitysuddenly and unexpectedly failed. There wasfor the bank to catch the signals that something bad was on thehorizon, but the company’s efforts to detect that were thwarted by an internal structure that allowed a single employee both to conduct and to oversee his own investment trades, and the breakdown of management oversight and internalcontrol systems (Mitroff et al., 1996). Likewise, looking in retrospect, McDonald’s fast food chain was given the prodromalsymptoms before the elderly lady sued them for the spilling ofa very hot cup of coffee on her lap - an event that resulted in a substantial financial loss and tarnished image of thecompany. Numerous consumers had complained about thetemperature of the coffee. The warning light was on, but the company did not pay attention. It would have been much simplerto pick up the signal, or to check the symptom, than facing the consequences.In another case, Jack in the Box, a fast food chain, had several customers suffer intestinal distress after eating at their restaurants. The prodromal symptom was there, but the company took evasive action. Their initial approach was to lookaround for someone to blame. The lack of attention, the evasiveness and the carelessness angered all the constituent groups, including their customers. The unfortunate deaths thatptoms,occurred as a result of the company’s ignoring thesymand the financial losses that followed, caused the company to realize that it would have been easier to manage the crisis directly in the prodromal stage rather than trying to shift theblame.Acute crisis stageA prodromal stage may be oblique and hard to detect. The examples given above, are obvious prodromal, but no action wasWebster’s New Collegiate Dictionary, an acute stage occursacutewhen a symptom “demands urgent attention.” Whether the acutesymptom emerges suddenly or is a transformation of a prodromalstage, an immediate action is required. Diverting funds and other resources to this emerging situation may cause disequilibrium and disturbance in the whole system. It is onlythose organizations that have already prepared a framework forthese crises that can sustain their normal operations. For example, the US public roads and bridges have for a long time reflected a prodromal stage of crisis awareness by showing cracks and occasionally a collapse. It is perhaps in light of the obsessive decision to balance the Federal budget that reacting to the problem has been delayed and ignored. This situation has entered an acute stage and at the time of this writing, it was reported that a bridge in Maryland had just collapsed.The reason why prodromes are so important to catch is thatit is much easier to manage a crisis in this stage. In the caseof most crises, it is much easier and more reliable to take careof the problem before it becomes acute, before it erupts and causes possible complications (Darling et al., 1996). In andamage. However, the losses are incurred. Intel, the largest producer of computer chips in the USA, had to pay an expensiveprice for initially refusing to recall computer chips that proved unreliable o n on certain calculations. The f irmfirm attempted to play the issue down and later learned its lesson. At an acutestage, when accusations were made that the Pentium Chips were not as fast as they claimed, Intel quickly admitted the problem,apologized for it, and set about fixing it (Mitroff et al., 1996). Chronic crisis stageDuring this stage, the symptoms are quite evident and always present. I t isIt is a period of “make or break.” Being the third stage, chronic problems may prompt the company’s management to once and for all do something about the situation. It may be the beginning of recovery for some firms, and a deathknell for others. For example, the Chrysler Corporation was only marginallysuccessful throughout the 1970s. It was not, however, until the company was nearly bankrupt that amanagement shake-out occurred. The drawback at the chronic stage is that, like in a human patient, the company may get used to “quick fixes” and “band “band--aid”approaches. After all, the ailment, the problem and the crisis have become an integral partoverwhelmed by prodromal and acute problems that no time or attention is paid to the chronic problems, or the managers perceive the situation to be tolerable, thus putting the crisison a back burner.Crisis resolutionCrises could be detected at various stages of their development. Since the existing symptoms may be related todifferent problems or crises, there is a great possibility thatthey may be misinterpreted. Therefore, the people in charge maybelieve they have resolved the problem. However, in practicethe symptom is often neglected. In such situations, the symptomwill offer another chance for resolution when it becomes acute,thereby demanding urgent care. Studies indicate that today anincreasing number of companies are issue-oriented and searchfor symptoms. Nevertheless, the lack of experience in resolvinga situation and/or inappropriate handling of a crisis can leadto a chronic stage. Of course, there is this last opportunityto resolve the crisis at the chronic stage. No attempt to resolve the crisis, or improper resolution, can lead to grim consequences that will ultimately plague the organization or even destroy it.It must be noted that an unsolved crisis may not destroy the company. But, its weakening effects can ripple through the organization and create a host of other complications.Preventive effortsThe heart of the resolution of a crisis is in the preventiveefforts the company has initiated. This step, similar to a humanbody, is actually the least expensive, but quite often the mostoverlooked. Preventive measures deal with sensing potential problems (Gonzales-Herrero and Pratt, 1995). Major internalfunctions of a company such as finance, production, procurement, operations, marketing and human resources are sensitive to thesocio-economic, political-legal, competitive, technological, demographic, global and ethical factors of the external environment. What is imminently more sensible and much more manageable, is to identify the processes necessary forassessing and dealing with future crises as they arise (Jacksonand Schantz, 1993). At the core of this process are appropriate information systems, planning procedures, anddecision-making techniques. A soundly-based information system will scan the environment, gather appropriate data, interpret this data into opportunities and challenges, and provide a concretefoundation for strategies that could function as much to avoid crises as to intervene and resolve them.Preventive efforts, as stated before, require preparations before any crisis symptoms set in. Generally strategic forecasting, contingency planning, issues analysis, and scenario analysis help to provide a framework that could be used in avoiding and encountering crises.出处:出处:Toby TobyJ. Kash and John R. Darling . Crisis management: prevention, diagnosis 179-186二、翻译文章标题:危机管理:预防,诊断和干预译文:本文的前提是,如果该公司做好准备得话,危机可以更有效地进行管理。
外文文献翻译(附原文)外文译文一:产业集群的竞争优势——以中国大连软件工业园为例Weilin Zhao,Chihiro Watanabe,Charla-Griffy-Brown[J]. Marketing Science,2009(2):123-125.摘要:本文本着为促进工业的发展的初衷探讨了中国软件公园的竞争优势。
产业集群深植于当地的制度系统,因此拥有特殊的竞争优势。
根据波特的“钻石”模型、SWOT模型的测试结果对中国大连软件园的案例进行了定性的分析。
产业集群是包括一系列在指定地理上集聚的公司,它扎根于当地政府、行业和学术的当地制度系统,以此获得大量的资源,从而获得产业经济发展的竞争优势。
为了成功驾驭中国经济范式从批量生产到开发新产品的转换,持续加强产业集群的竞争优势,促进工业和区域的经济发展是非常有必要的。
关键词:竞争优势;产业集群;当地制度系统;大连软件工业园;中国;科技园区;创新;区域发展产业集群产业集群是波特[1]也推而广之的一个经济发展的前沿概念。
作为一个在全球经济战略公认的专家,他指出了产业集群在促进区域经济发展中的作用。
他写道:集群的概念,“或出现在特定的地理位置与产业相关联的公司、供应商和机构,已成为了公司和政府思考和评估当地竞争优势和制定公共决策的一种新的要素。
但是,他至今也没有对产业集群做出准确的定义。
最近根据德瑞克、泰克拉[2]和李维[3]检查的关于产业集群和识别为“地理浓度的行业优势的文献取得了进展”。
“地理集中”定义了产业集群的一个关键而鲜明的基本性质。
产业由地区上特定的众多公司集聚而成,他们通常有共同市场、,有着共同的供应商,交易对象,教育机构和其它像知识及信息一样无形的东西,同样地,他们也面临相似的机会和威胁。
在全球产业集群有许多种发展模式。
比如美国加州的硅谷和马萨诸塞州的128鲁特都是知名的产业集群。
前者以微电子、生物技术、和风险资本市场而闻名,而后者则是以软件、计算机和通讯硬件享誉天下[4]。
e c o l o g i c a l e n g i n e e r i n g 28(2006124–130a v a i l ab l e a t w w w.sc i e n c ed i re c t.c omj o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /e c o l e n gPlant-biofilm oxidation ditch for in situ treatm ent of polluted watersQi-Tang Wu a ,∗,Ting Gao a ,Shucai Zeng a ,Hong Chua ba College of Natural Resources and Environment,South China Agricultural University,Guangzhou 510642,ChinabDepartment of Civil and Structural Engineering,Hong Kong Polytechnic University,Hung Hom,Kowloon,Hong Kong SAR,Chinaa r t i c l ei n f o Article history:Received 17December 2005Received in revised form 16May 2006Accepted 18May 2006Keywords:Plant-biofilm oxidation ditch (PBFODIn situWastewater treatmenta b s t r a c tEutrophication of surface water bodies is a problem of increasing environmental and ecolog-ical concern worldwide and is particularly serious in China.In the present study,oxidation ditches were connected to a lake receiving municipal sewage sludges.T wo 24m 2(width 2m,length 12mparallel plastic oxidation ditches material were installed on a lake near the inlet of the municipal sewage.Zizania caduciflora and Canna generalis were grown in the ditches with plastic floating supporters for the removal of N and P from the sewage.The experiment was conducted firstly with municipal sewage in autumn–winter seasons for about 150daysunder the following conditions:2m 3/h influent flow,0.75kW jet-flow aerator(air/water of 5,18h HRT (hydrological retention timeand a return ratio of 10.Then it was run with the polluted lake water in summer–autumn for about 160days with an aerator of 1.25kW and an influent of 6m 3/h (air/water 3.3,HRT 6h.The performance was quite stable during the experimental period for the municipal sewage treatment.The average removal rates of COD (chemical oxygen demand,SS (suspended solids,TP (total phosphorus,NH 4+-N and inorganic-N were 70.6,75.8,72.6,52.1and50.3%,respectively.For the polluted lake water treatment,the average concentrations of COD,NH 4+-N and TP were 42.7,13.1and 1.09mg/L,respectively,in the influent and were 25.1,6.4and 0.38mg/L,respectively,in the effluent.The capacity of the plants to remove N and P by direct uptake was limited,but the indi-rect mechanisms also occurred.The proposed process,transforming the natural lake into a wastewater treatment plant,could evidently reduce the costs of the sewage collection,the land space requirement and the construction compared with conventional sewage treat-ment plants,and is especially suited to conditions in south China and south-east Asia.©2006Elsevier B.V .All rights reserved.1.IntroductionMany water bodies are subject to eutrophication due to eco-nomic constraints in reducing point sources of nutrients and/or to a high proportion of diffuse sources,and the prob-lem is particularly common in China because the proportion of treated municipal sewage is still low due to the relatively high capital investmentrequired.Accordingly,43.5%of 130investi-gated major lakes in China were found to be highly eutrophied∗Corresponding author .Tel.:+862085280296;fax:+862085288326.E-mail address:qitangwu@ (Q.-T.Wu.and 45%were of intermediate status (Li et al.,2000.These pol-luted lakes were mainly located in economically developed regions and especially around cities where large amounts of municipal sewage are discharged without appropriate treat-ment.Increasingly,natural or constructed wetlands,including buffer zones(Correll,2005,are being used for removal of pol-lutants from wastewater or for treatment of stormwater runoff from agricultural land and other non-point sources (Mitsch ete c o l o g i c a l e n g i n e e r i n g28(2006124–130125Table1–COD and BOD5of the study lake sampled at three points for5days inMay2003COD(mg/LBOD5(mg/LBOD5/COD13May89.5135.700.4083.3334.500.4189.5136.600.4114May55.5624.800.4589.5135.200.3949.3820.900.4227May105.1141.300.3981.0832.300.40111.1141.000.3728May60.0026.830.4563.3327.700.4463.3327.000.4329May90.0035.700.4093.3337.000.40117.9949.400.42al.,2000;Coveney et al.,2002;Belmont et al.,2004.However, this method requires a large land area in addition to the lake in question.For in situ treatment of hypereutrophic water bodies where the transparency of the water does not allow regrowth of submerged macrophytes,phosphorus precipitation in eutrophic lakes by iron application(Deppe and Benndorf, 2002or by additions of lime(Walpersdorf et al.,2004has been reported.Aeration of river water has been employed to remediate polluted rivers since the1970s(Wang et al.,1999. Increasing oxygen transfer inflow by stones placed in rivers was studied by Cokgor and Kucukali(2004.Growingfloating aquatic macrophytes(Sooknah and Wilkie,2004or terrestrial green plants usingfloating supports(Li and Wu,1997,physical ecological engineering(PEEN(Pu et al.,1998,and biotic addi-tives have also been applied(Chen,2003.However,these sim-ple designs do not constitute a real water treatment system and the efficiencies of these treatments are unsatisfactory.Activated sludge systems have been proved efficient treat-ing municipal sewage since the1960s(Ray,1995.However, this type of system has not been used for in situ remediation of polluted lakes or rivers.In the present study,the oxidation ditch technique was adopted on a lake receiving municipal sewage sludge.Floating green plants and the biofilms com-prisingfloating materials and plant roots were also added to enhance N and P removal.A pilot scale experiment was set up to test the feasibility and performance of the plant-enhanced oxidation ditch for in situ treatment ofboth the municipal sewage and the polluted lake water.2.Experimental2.1.Site descriptionThe study lake was situated at South China Agricultural Uni-versity,Guangzhou,China.The area of the lake was about 10000m2and the depth0.5–3m.This lake received the munic-ipal sewage from the residential area around the university.Fig.1–Surface arrangement of the plant-biofilm oxidation ditch and the waterflows.(1Wall of nylon tissue;(2nets of5mm;(3nets of0.25mm;(4oxidation ditch;(5jet-flow aerator;(6water pump;(7floating green plants;(8sewage entry.2.2.Establishment of the plant-biofilm oxidationditchesT wo24m2(width2m,length12mparallel oxidation ditches made of plastic materials were installed along the lake bank near the sewage inlet.The inner ditch was made of cement and the outer ditch was isolated with nylon tissues andfix-ing PVC(polyvinyl chloridetubes.Fig.1showsthe surface arrangement and the waterflow path.The coarse suspended solids in the influent werefiltered by two pl astic nets,one with a pore size of5mm and the other with a pore size of0.25mm,whereas the suspended solids in the effluent werefiltered by a plastic net with a pore size of 0.25mm.Zizania caduciflora and Canna generalis were grown in the ditch with theplast icfloating supporters which held the plants in position.Thefloating supporters were made of closed126e c o l o g i c a l e n g i n e e r i n g28(2006124–130PVC tubes and nylon nets and each was3.6m2.Zizania caduci-flora was grown on twofloating supporters an d Canna gener-alis on another two supporters.The plants were planted in four columns andfive lines.The twofloating supporters with Canna generalis were near the influent and the two with Zizania caduciflora were near the effluent.The entire disposal system is shown in Photo1.2.3.Conduct of the experimentsAn experiment was conductedfirstly on municipal sewage in autumn–winter seasons of2003–2004for about150days. The aeration of the oxidation ditch was achieved using a jet-flow aerator of0.75kW(Aqua Co.,Italy;air generation10m3/h, water jet rate22–28m3/h.The water sampling started on18 September2003and endedon12February2004.The influent was2m3/h created by a water pump of0.37kW.With the jet-flow aerator of0.75kW the theoretical air/water ratio was5, HRT was18h and the return ratio was10–13.The system was then run with the polluted lake water in summer and autumn2004for about160days with an aerator of1.25kW and with an influent of6m3/h(air/water3.3,HRT 6h.The influent was not created by water pump but by the driving fo rce of the jet-flow aerator.The water sampling for the second run started on15May2004and endedon15October 2004.2.4.Sampling and analysisThe influent and effluent were sampled every3–5days at 08:00–09:00a.m.andat17:00–18:00p.m.,each with three sam-pling re plicates for thefirst run.For the second run,the influ-ent and effluent were sampled1day a week.The water sam-pler took0–30cm surface water.The samples were analyzed for COD Cr,BOD5,SS,TP,NO3−-N,NH4+-N and pH according to standard methods(APHA,1995.The plant s were transplanted ontofloating supporters two weeks before water sampling and thefirst harvest was carried out60days later and at the termination of thefirst run for the municipal sewage.The plant biomass and N and P con-tents were measured according to the methods proposed by the Soil and Agro-Chemical Analysis Committee of China(Lu, 2000.The total uptakes of N and P were calculated and com-pared with the total removal of these elements calculated by the cumulative removal each day following measurement of a water sample.Total N removal=(average N in influent−average N in effluent×48×D iwhere48was the treated water volume per day in m3/day;D i was the number of days following the water sampling and before the next sampling.3.Results and discussionTable2shows the removal of COD Cr and SS by plant-biofilm oxidation ditch for the treatment of the municipal sewage in autumn–winter seasons of2003–2004.The removal of COD Cr varied from60to79%with an average of70%for the influent COD Cr ranging from100to200mg/L,a nd resulted in effluent COD Cr valuesfrom30to55mg/L(Table2,Fig.2.The average removal percentage was about75%for SS and variedfrom68to82%(Table2.The effluent SS was about 30mg/L which is the effluent limit value of the second grade for the sewage treatment plants in China(GB18918,2002 (Fig.3,for the influents varying from60to240mg/L.The average NH4+-N removal from influent was52%,which was lower in winter than in autumn(Table3.This may be due to lower bacterial activity in winter,but theinfluent NH4+-NTable2–Removal of COD and SS by the plant-biofilm oxidation ditch for the in situ treatment of municipal sewage each month in autumn–winter seasons of2003–2004Period Sampled days Water temperature(◦CInfluent(mg/LEffluent(mg/LRemoval(%COD Cr18–30September528.0118.54(3.01a34.34(7.8367.74 3–28October826.1123.91(4.0333.51(4.2672.661–7November326.0153.94(2.7337.60(3.8175.4918–28November423.1170.22(4.2835.45(5.3778.711–15December419.3180.36(8.2039.24(7.0677.6511–31January314.5128.46(3.6652.04(5.2359.504–12February216.8178.35(4.1662.86(5.8362.47Average150.54(4.3042.15(5.6370.60SS18–30September528.0160.4041.6074.18 3–28October826.1144.3826.2581.171–7November326.0116.0033.3370.7918–28November423.1111.7521.5080.981–15December419.390.5028.5068.4211–31January314.5104.0017.3382.384–12February216.8120.5033.0072.57Average121.0828.7975.78e c o l o g i c a l e n g i n e e r i n g28(2006124–130127Fig.2–COD in the influent and effluent of the plant-biofilm oxidation ditch for the in situ treatment of municipal sewage in autumn–winter seasons of2003–2004.was also higher in winter(Fig.4probably because of lower water consumption in the cold season.The total inorganic-N removal was similar to that for NH4+-N(Table3.NO3−-N concentrations were rather similar in the influent and the effluent.The total P removal varied from63to78%and was higher and more regular than N removal(Table3.The P concentra-tion in treated effluent was about1mg/L(Fig.5and conformed to the Chinese municipal sewage treatment standard which is set to3mg/L for second grade regions and1.5forfirst grade regions(GB18918,2002.Fig.6shows typical changes in the water quality param-eters for the sampling points from inlet to outlet.Thisindi-Fig.3–Suspended solids concentration in the influent and effluent of the p lant-biofilm oxidation ditch for the in situ treatment of municipal sewage in autumn–winter seasons of2003–2004.cates that COD and SS decreased gradually,but NH4+-N and TP dropped substantially following the mixing with the return water by the aerator and then decreased slowly,while NO3−-N and pH of the water remained virtually unchanged.The water DO increased dramatically following the aeration,decreased slowly thereafter and remained rather high even in the efflu-ent(about5.5mg/L.For the second run treating the polluted lake water on-site,the average influent COD Cr was42.7mg/L and the effluent 25.1mg/L for about160days during summer–autumn seasons (Fig.7.The removal of NH4+-N was about50%from about13.1 to6.4mg/L.Total-P in the effluents was rather stable,bei ngTable3–The removal of N and P by the plant-biofilm oxidation ditch for the in situ treatment of municipal sewage for each month in autumn–winter seasons of2003–2004Period Sampled days Water temperature(◦CInfluent(mg/LEffluent(mg/LRemoval(%NH4+-N18–30September528.020.60(0.30a7.16(0.2264.72 3–28October826.126.55(0.2310.15(0.2061.671–7November326.030.00(0.4113.67(0.2254.5118–28November423.135.15(0.7915.95(0.2653.991–15December419.335.89(0.3515.93(0.2755.1511–31January314.530.57(0.6918.59(0.2236.634–12February216.835.23(0.0521.61(0.0637.72Average30.57(0.4014.72(0.2152.06NH4+-N+NO3−-N18–30September528.023.06(0.159.24(0.1159.94 3–28October826.128.31(0.1212.01(0.1457.571–7November326.031.42(0.2114.58(0.1153.5918–28November423.136.32(0.4016.81(0.1353.721–15December419.337.41(0.1917.54(0.1453.1111–31January314.531.96(0.3720.07(0.1337.204–12February216.837.11(0.0323.35(0.0337.08Average32.23(0.2116.23(0.1150.32TP18–30September528.0 3.56(0.070.81(0.0475.56 3–28October826.1 4.01(0.140.87(0.0478.241–7November326.0 4.37(0.13 1.20(0.0472.5618–28November423.1 4.89(0.16 1.13(0.0776.661–15December319.5 4.86(0.80 1.38(0.2371.07 11–31January314.5 3.75(0.45 1.35(0.0363.32 4–12February216.8 4.75(0.10 1.51(0.0566.20 Average 4.31(0.16 1.16(0.0471.89128e c o l o g i c a l e n g i n e e r i n g 28(2006 124–130Fig.4–NH 4+-N concentration in the influent and effluent of the plant-biofilm oxidation ditch for the in situ treatment of municipal sewage in autumn–winter seasons of2003–2004.Fig.5–Total-P concentration in the influent and effluent of the plant-biofilm oxidation ditch for the in situ treatment of municipal sewage in autumn–winter seasons of2003–2004.Fig.6–T ypical changes in the pollutants in theplant-biofilm oxidation ditch during the in situ treatment ofFig.7–The influent and effluent concentrations of COD (up,NH 4+-N (medianand total-P (bottomin theplant-biofilm oxidation ditch treating polluted lake water.about 0.38mg/L from an average of 1.09mg/L in the influents.The removal of COD Cr ,NH 4+-N and Total-P was then quite sat-isfactory both for the municipal sewage and the polluted lake water.The removal of N and P was somewhat higher than con-ventional oxidation ditches,perhaps due to the existence of the plant-biofilm in the studiedsystem.However,the direct uptake rates of N and P by green plants were almost negligi-ble compared to the total removal of these elements by the whole system (Table4.However,the plants may have cre-ated localized anaerobic conditions by their root exudates and dead biomass and enhance the denitrification of N by micro-organisms as occurs in constructed wetlands (Hone,2000.Besides the green plants,the proposed system also con-tains biofilm coated to the plastic materials.The high velocity of return-fluent was different to the conventional oxidation ditch.Kugaprasatham et al.(1982showed that the increase of the fluent velocity could increase the density of the biofilm if the nutrient conditions were suitable for bacteria growth.Simultaneous nitrification/denitrification (SND(Van Mun ch etal.,1996may also occur in the system.Concerning the P removal of the system,biological phos-phate removal processes may occur but were not significant because there was no sludge removal and very little sludge precipitation after the run for treatment of municipal sewage.This may partly due to the existence of some ferric chains which were added to precipitate and fix the nylon tissue to the lake bottom,with formation of precipitates of ferric phos-e c o l o g i c a l e n g i n e e r i n g 2 8 ( 2 0 0 6 124–130 129 Table 4 – Proportions of N and P uptake by plants and total removal in the plant-biofilm oxidation ditch treating municipal sewage Date Days ZCa Harvested fresh biomass (g CG ZC 5 September–4 November 5 November–6 January Total or average a Plant uptake (g N CG 5.30 13.03 System removal (kg N CG P Percent of plant uptake N (% P (% P ZC 0.88 0.24 2.79 60 63 123 2200 625 9725 2750 4150 4.85 1.20 24.38 0.72 0.95 37.63 65.45 103.1 7.13 12.78 19.91 0.03 0.02 0.02 0.02 0.01 0.01 ZC: Zizania caduciflo ra; CG: Canna generalis. tained for at least 1 year. The actual mechanisms still remain to be identified. The oxidation ditch has been used for many years worldwide as an economical and efficient wastewater treatment technology that can remove COD, nitrogen and a fraction of the phosphorusefficiently. Anaerobic tanks (Liu et al., 2002 and phased isolation ditch systems with intra-channel clarifier (Hong et al., 2003 were added to the system to increase the TP removal efficiency. The proposed process takes an artificial process in combination with natural purification, transforming the natural lake into the wastewater treatment plant, and could evidently reduce the costs of sewage collection, the landspace requirement and the construction costs compared with the conventional sewage treatment plants. This process could be especially suitable to subtropical regions and to many water bodies in south China and southeast Asia where sewage treatment facilities are not well established. China. The authors are grateful to Dr. P. Christie, Department of Agricultural and Environmental Science, Queen’s University Belfast, UK, and Dr. Y. Ouyang, Department of Water Resources, St. Johns River Water Management District, Palatka, FL, USA, for their valuable suggestions and language corrections. references 4. Conclusions The present study adapted the oxidation ditch on the lake surface for in situ treatment of municipal sewage or polluted lake water in combination with plant biofilms for performing N and P removal, and running experiments at pilot scale for about 1.5 years resulted in the following observations: (1 The system was quite satisfactory and stable for treatment of municipal sewage and polluted lake water in removing COD, NH4 + -N and P. (2 The direct uptake of N and P by plants was negligible in comparison with the totalremoval by the system, but indirect mechanisms via plant root exudates and biofilms merit further studies. (3 The proposed process could dramatically reduce the costs of sewage collection, the land-space requirement and the construction costs compared with conventional sewage treatment plants; might be suitable for treatment of both municipal sewage and polluted lake water; and could lead to the promotion of wastewater treatment in many developing countries. Acknowledgements This study was funded by Department of Science and Technology of Guangdong Province (Grant no. 2004B33301007, American Public Health Association (APHA, 1995. Standards Methods for the Examination of Water and Wastewater, 19th ed. American Public Health Association, Washington, DC. Belmont, M.A., Cantellano, E., Thompson, S., Williamson, M.,S’anchez, A., Metcalfe, C.D., 2004. Treatment of domestic wastewater in a pilot-scale natural treatment system in central Mexico. Ecol. Eng. 23, 299–311. Chen, Y.C., 2003. Bioremediation Engineering of Polluted Environment. Chemical Industry Press, Beijing, p. 304 (in Chinese. Cokgor, S., Kucukali, S., 2004. Oxygen transfer in flow around and over stones placed in a laboratory flume. Ecol. Eng. 23, 205–219. Correll, D.L., 2005. Principles of planning and establishment of buffer zones. Ecol. Eng. 24, 433–439. Coveney, M.F., Stites, D.L., Lowe, E.F., Battoe, L.E., Conrow, R., 2002. Nutrient removal from eutrophic lake water by wetland filtration. Ecol. Eng. 19, 141–159. Deppe, T., Benndorf, J., 2002. Phosphorus reduction in a shallow hypereutrophic reservoir by in-lake dosage of ferrous iron. Water Res. 36, 4525–4534. Hone, A.J., 2000. Phytoremediation by constructed wetlands. In: Terry, N., Banuelos, G. (Eds., Phytoremediation of Contaminated Soil and Water. Lewis Publishers, pp. 13–40. Hong, K.H., Chang, D., Hur, J.M., Han, S.B., 2003. Novel phased isolation ditch system for enhanced nutrient removal and its optimal operating strategy. J. Environ. Sci. Health Part A 38, 2179–2189. Kugaprasatham, S., Nagaoka, H., Ohgaki, S., 1982. Effect of turbulence on nitrifying biofilms at non-limiting substrate conditions. Water Res. 26, 1629–1638. Li, F.X., Xin, Y., Chen, W., 2000. Assessment of eutrophication level of lakes. Chongqing Environ. Sci. 22, 10–11 (in Chinese. Li, F.B., Wu, Q.T., 1997.Domestic wastewater treatment with means of soilless cultivated plants. Chin. J. Appl. Ecol. 8, 88–92 (in Chinese. Liu, J.X., Wang, B.Z., van Groenestijn, J.W., Doddema, H.J., 2002. Addition of anaerobic tanks to an oxidation ditch system to enhance removal of phosphorus from wastewater. J. Environ. Sci. 14, 245–249.130 e c o l o g i c a l e n g i n e e r i n g 2 8 ( 2 0 0 6 124–130 Lu, R.K., 2000. Soil and Agricultural Chemistry Analysis. China Agriculture Press, Beijing (in Chinese. Mitsch, W.J., Horne, A.J., Nairn, R.W., 2000. Nitrogen and phosphorus retention in wetlands—ecological approaches to solving excess nutrient problems. Ecol. Eng. 14, 1–7. Pu, P., Hu, W., Yan, J., Wang, G., Hu, C., 1998. A physico-ecological engineering experiment for water treatment in a hypertrophic lake in China. Ecol. Eng. 10, 179–190. Ray, B.T., 1995. Environmental Engineering. PWS Publishing Company, New York, pp. 299–341. Sooknah, R.D., Wilkie, A.C., 2004. Nutrient removal by floating aquatic macrophytes cultured in anaerobically digested flushed dairy manure wastewater. Ecol. Eng. 22, 27–42. Van Munch, E.P., Land, P., Keller, J., 1996. Simultaneous nitrification and denitrification in bench-scale sequencing batch reactors. Water Sci. Technol. 20,277–284. Wang, C.X., Lin, H., Shi, K.H., 1999. Restoration of polluted river by pure oxygen aeration. Shanghai Environ. Sci. 18, 411–413 (in Chinese. Walpersdorf, E., Neumann, T., Stuben, D., 2004. Efficiency of natural calcite precipitation compared to lake marl application used for water quality improvement in an eutrophic lake. Appl. Geochem. 19, 1687–1698.。
Business process re-engineering –saviour or just another fad?One UK health care perspectiveAnjali PatwardhanHealth Service Management Centre,Birmingham,UK,and Dhruv Patwardhan University of Newcastle,Newcastle upon Tyne,UKAbstractPurpose –Pressure to change is politically driven owing to escalating healthcare costs and an emphasis on efficiency gains,value for money and improved performance proof in terms of productivity and recently to some extent by demands from less satisfied patients and stakeholders.In a background of newly immerging expensive techniques and drugs,there is an increasing consumer expectation,i.e.quality services.At the same time,health system managers and practitioners are finding it difficult to cope with demand and quality expectations.Clinicians are frustrated because they are not recognised for their contribution.Managers are frustrated because meaningful dialogue with clinicians is lacking,which has intensified the need for change to a more efficient system that satisfies all arguments about cost effectiveness and sustainable quality services.Various strategies,originally developed by management quality “gurus”for engineering industries,have been applied to health industries with variable success,which largely depends on the type of health care system to which they are applied.Design/methodology/approach –Business process re-engineering is examined as a quality management tool using past and recent publications.Findings –The paper finds that applying business process re-engineering in the right circumstances and selected settings for quality improvement is critical for its success.It is certainly “not for everybody”.Originality/value –The paper provides a critical appraisal of business process re-engineering experiences in UK healthcare.Lessons learned regarding selecting organisations and agreeing realistic expectations are addressed.Business process re-engineering has been evaluated and reviewed since 1987in US managed health care,with no clear lessons learned possibly because unit selection and simultaneous comparison between two units virtually performing at opposite ends has never been done before.Two UK pilot studies,however,add useful insights.Keywords Business process re-engineering,Total quality management,Continuous improvement,Medical management,Health services,United KingdomPaper type ViewpointHistory of quality management in health careTo know how health care organisations became interested in industrial quality development tools and how business process re-engineering (BPR)emerged as an option,we have to go back to 1987when the Quality Improvement in Health Care National Demonstration Project (NDP)was launched as an experiment (Godfrey,n.d.).A total of 21health-care organisations participated and promised to support this study lasting eight-months.The aim was to look at the applicability of industrial quality-improvement methods to health care.Support included free consulting,The current issue and full text archive of this journal is available at/0952-6862.htmBPR –saviour or just a fad?289Received 29November 2006Revised 10February 2007Accepted 25May 2007International Journal of Health Care Quality Assurance Vol.21No.3,2008pp.289-296q Emerald Group Publishing Limited 0952-6862DOI 10.1108/09526860810868229materials,access to training courses and reviews.The funding companies included many of the USA’s leading organisations such as Corning,Ford,Hewlett-Packard,IBM and Xerox.At the final stages of the project evaluations it was clear that out of 21organisations,15health care organisations made significant progress –mainly financial and patient satisfaction gains,target and project time keeping and investment in research and development.The NDP was extended for three years,which eventuallyevolved into the Institute for Healthcare Improvement,a not-for-profit organisation –dedicated to providing health-care quality management ter,BPR emerged as an alternative for managers in organisations frustrated with slow improvements,not encompassing the whole organisation experiencing total quality management (TQM).The TQM key target was to convert an organisation’s structure,culture and services to patient/consumer rather than organisation-focused goals (Harvey and Millett,1999).Why change?Traditionally health care systems were mostly “governed”by clinicians (Shutt,2003)because patient outcomes;that is,recovery from illness,were the sole responsibility of all professionals directly involved in patient plexity and variance in health care studies reveal that outcome has many determinants;i.e.pharmacy,pathology,technical support and information technology.It was also realised that cost containment and good quality care needed teamwork,communication,time management,etc.(Shutt,2003).Sir Roy Griffiths,in the early 1980s,developed hospital general management and the greater involvement of clinicians in resource management initiatives (DHSS,1984).Today,apart from political motives,change is driven by escalating health care costs,increased demands for quality care,value for money services,patient expectation and third-party payers in managed health care systems.These intensified the need for change to more efficient health care systems.What is BPR?BPR,also known business transformation and process change management,was introduced to the business world by Frederick Taylor in his article The Principles of Scientific Management in the 1900s (wikipedia,2006).In the 1990s,Hammer and Champy (1993)introduced Reengineering the Corporation ,which gave birth to BPR.BPR is “the analysis and design of workflows and processes within and between organizations”(Devenport and Short,1990,p.11).Teng et al.(1994)on the other hand,defined BPR as critical analysis and radical redesign of existing business processes to achieve breakthrough improvements in performance measures.Hammer and Champy (1993),similarly,defined BPR as fundamentally rethinking and radically redesigning business processes to achieve dramatic improvements in critical contemporary performance measures such as cost,quality,service and speed.From a health care viewpoint,BPR is a management approach that rethinks present practices and processes in business and its interactions.It attempts to improve underlying process efficiency by applying fundamental and radical approaches by either modifying or eliminating non-value adding activities and redeveloping the process/structure/culture (McNulty and Ferlie,2000).However,in the health sector,a wide variety of patient groups make the health care service a complex project to redesign along these lines,thereby rendering changes context and time sensitive.IJHCQA 21,3290BPR key featuresHealth care’s BPR approach means starting with clean slate and rethinking services using a patient-focused approach.With the benefit of hindsight BPR identifies delays caused by unnecessary steps or potential errors that are built into processes.It is presumed that redesigning processes by removing these errors dramatically improves care quality.The BPR approach,therefore,raises expectations about dramatic results. Consequently,high returns on investment are anticipated.The process,planned strategically,is explained in Taylor’s BPR framework(wikipedia,2006): .defining BPR’s purpose and goal;.identifying requirements that meet clients’needs;.defining project scope,including appropriate activities such as process mapping;.assessing the environment using,for example,force-field analyses;.re-engineering business processes and activities;.implementing redesigned processes;and.monitoring redesign success and failure.BPR vs TQMComparing BPR with other popular quality management methods helps us to appreciate and highlight key features in a health care context(Harvey and Millett,1999).TQM or continuous quality improvement(CQI)refers to programmes and initiatives that emphasise incremental improvement in work processes and outputs over an open-ended time period.In contrast,BPR refers to discrete initiatives intended to radically redesign and improve work processes within a time frame.Some people think TQM is best suited to quality in health care improvement though it is an incremental stepwise,slow but holistic approach.In practice,TQM and BPR are customer-oriented and both encourage managers and practitioners to take a customer view point.Both are team approaches that involve process control.The TQM protagonists assume that existing health care practices and systems are principally right but improvements are needed.The BPR supporters,on the other hand,assume that health care systems and practices areflawed and need replacing.Those using TQM expect and believe in stepwise increments in performance as opposed to BPR experts who look for dramatic results.TQM aims to improve all levels for all stakeholders and at all steps,while BPR aims at specified areas only.Standardisation and supporting documentation is a TQM key point.Believing in consistent and cost-effective performance and minimising process or system defects, prevents rather than corrects problems(Field and Swift,1996).Those that use the BPR approach,on the other hand,areflexible and assume that standardisation increases process complexity(Harvey and Millett,1999).Nevertheless,BPR is a drastic change leading to staff resistance.Moreover,it is a top-down approach,so management support and commitment is vital to success.Innovation,therefore,is a risky process when used for“sick organisations”.The TQM incremental method,on the other hand,follows a gradual approach that is mostly bottom-up.It involves employees and often based on Deming’s principles that direct improvements through plan-do-study-act(PDSA)cycle.TQM,therefore,is suitable for improving quality in any organisation,although some amendments to suit context may be needed.Application in managed health care generated different results BPR–saviour or just a fad?291when dissimilar processes were applied in different scenarios.Business process re-engineering,therefore,may not suite everyone because it works better when applied to sick organisations or in fundamentally defective systems (Bashein et al.,1994).The TQM approach is about a cultural change as it is built into practices hooked on daily routines.The BPR method is a target-oriented process that is time sensitive because if not completed as planned then success may be jeopardised.The TQM primary enableris statistical process control,while in BPR it is information and technology (Harvey and Millett,1999).Advantages of applying BPR to health service quality improvementUsing BPR in the health sector was a response to frustrations amongst managers in organisations who perceived TQM’s incrementalism and ability to achieve organisation-wide change had failed.King’s College Hospital experience (Grimes,2000;Harrison et al.,1992)suggests that BPR could be best tried to achieve previously unachieved levels of efficiency in scenarios when other efforts/methods had been unsuccessful.The driving forces for change were aspirations to develop a more efficient system that satisfies consumers’demands for service quality and value for money (Bowns and McNulty,1999).At the same time,BPR makes it possible to sustain such quality without necessarily costing more,even though we know that health care costs are rising steeply.The third and most important aspiration in the King’s project was to improve professionals’job satisfaction,what they felt they always deserved.The aim was to orient health care towards and focus on patients rather than organisation needs.The BPR approach focuses on rethinking and redesigning processes from scratch,giving staff opportunities to revisit services in detail,thereby pointing out improvement areas.It strips all non-value adding and unnecessary steps from the process to make services more efficient.Although it is managed top-down and dominated by managers and leaders,decision making is done at the coal-face,thereby empowering the team.The BPR approach provides a flexible work environment,culture and work practices.It can be valuable for organisations in deep difficulties and performing poorly.In such a crisis,re-engineering may be the only way organisations can survive (Harvey and Millett,1999).Where major structural and cultural deficiencies are identified or are obvious as a poor performance cause,BPR is the best way to handle that scenario –evident from King’s College Hospital experiences (Bowns and McNulty,1999).BPR limitations in health care quality improvementWe know that BPR is a top-down approach that staff may resist.It is cited by autonomous clinical professionals as “a brutal and inappropriate technique”(Jones,1996,p.4284).Implementing BPR in health care scenarios,where clinicians are key players,therefore,is not only difficult but also unsafe (McNulty and Ferlie,2000).Thus,BPR may lead to ownership loss and employee de-motivation because they are not involved in planning and change management.Generally,change processes are less-well understood by employees (Jones,1996,p.4284):Quality would seem unlikely to be forthcoming if re-engineering is imposed from the top down in a rigid and mechanistic fashion ...If organizational change is to be effective and sustainable,this will also require the active engagement of,and learning by,employees rather than grudging compliance with management diktat.IJHCQA 21,3292Quality improvement in European public services elaborated health care TQM and BPR as quality improvement tools.It was acknowledged that many business approaches to quality improvement,including TQM and re-engineering,failed to take account of health care’s complexity and the nature of professionalised knowledge.The language and values used in most of these projects were alien to clinicians and so were rejected as management fads.It seems that BPR requires massive culture and structure change if it is to improve quality of the same magnitude.It may be that radical overnight transformation may sound impressive but unrealistic.Structural and cultural change needs time to develop,be accepted and absorbed at all levels, particularly in health care settings.In short,BPR is a high-cost and high-risk project. Seventy-percent of all industries could not achieve their targets–a BPR success rate around30per cent.In the health care sector,on the other hand,from the literature we reviewed,there is no successfigure available.BPR carries an unrealistic scope and expectation most of the time,which may be a reason for its70per cent failure rate.Its top-down nature and success depends on sustained management commitment and inspirational leadership,which is not easily measured and may not be available up to the threshold needed.BPR may make only a unit change in time.To be meaningful,it needs to be followed by a CQI exercise.Once changes are brought about,BPR-based change needs CQI projects to have sustained results.It is always contested that BPR does not take account of human processes–evident from Jones’(1996,p.4284) quotation:Such a perspective is seen as promoting the idea that you can design a perfect process, implement it exactly as you planned and the organizational machine will carry it out faultlessly.Setting on one side questions about the reliability of this whole process,it is evident that BPR neglects the important role of human creativity in making process work. As we raised earlier,BPR usually innovates one process at a time rather than a whole organisation approach.The process that is changed,therefore,might not have an effect on overall organisational performance that can be measured especially those perceived by consumers.In other words,BPR may have a drastic effect on one specific process but none or very little on total organisational performance.A simple illustration for improving inpatient admissions shows that BPR alone cannot improve services.There will be need also to improve day care,outpatient,primary care and emergency services. All have an effect on an organisation’s inpatient services because they are interlinked and interdependent.Moreover,BPR’s effect can be difficult to assess in this context since NHS organisations lack specific measures(Bowns and McNulty,1999).The extent to which BPR is applicable to health care systemsThe UK BPR health care experience comes from two centrally funded pilot studies:(1)King’s College Hospital,London(KCH);and(2)Leicester Royal Infirmary(LRI).The KCH project was evaluated by a Brunel team(Packwood et al.,1998;Grimes,2000) and the LRI scheme by Sheffield and Warwick(Bowns and McNulty,1999).Employees in these organisations shared their BPR experiences during evaluation.Consequently, both studies generated interesting and valuablefindings as they highlighted to what extent BPR could be applied to health care systems.However,the two hospitals were BPR–saviour or just a fad?293extremes,i.e.KCH was a “sick”unit at the time of the study.LRI,on the other hand,was one of the best teaching hospitals (McNulty and Ferlie,2000)with little scope to improve.At the end of the pilot studies it was evident from reports that both hospitals could not reach expectations especially the drastic changes and improvements anticipated at the beginning of the BPR projects.Both reduced waiting times and length of stay along with faster diagnostic processes.King’s,over and above theseimprovements,also made £1million savings (Grimes,2000)–attributed to “waste reduction”by process mapping followed by removing non-value adding activities and by increasing efficiency in the renewed system (Packwood et al.1998).This suggests that BPR is not for everybody and that selecting units to which BPR can be applied is important to achieve desired results.When the two trusts ran the pilot,they also continued to work on their generic and core improvement initiatives at different levels in the process and so it was difficult to attribute success to BPR alone or to assess its relative contribution to overall improvements.One approach to identify suitable sub processes for applying BPR is process mapping from “door to door”,which helps capture all the process components and applying a lean approach (Jones and Mitchell,2006,p.23).Identifying value-added activities highlights the non-value-added ones.Each non-value-added activity can be measured and analysed to assess its impact and ways to eliminate activity.Resource availability,deadline,cost,generic skills and above all,urgency to change help users select the right improvement tool.Also,as raised earlier,change management success is closely related to team morale,ownership and motivation.To achieve quality in health care services,therefore,two key staff groups –managers and clinicians,who come from different cultural backgrounds and are knowledgeable in different ways,need to work as a team.Understanding and cooperation are crucial if difficult tasks are to be accomplished (Shortell et al.1998).However,BPR’s failure to consider the human aspects of processes may make it difficult to integrate BPR into health care services.The BPR approach sounds impressive but unrealistic because soft structural and cultural change need time to develop particularly in health care settings.We believe that BPR can help to improve health services if it is meticulously planned and applied diligently.In short,even with all BPR’s limitations,it is still capable of delivering dramatic results not least because it forces staff to think from outside the scenario or process as a whole and work to deadlines (Bowns and McNulty,1999).Conclusions and recommendationsHealth care is a more complex system than any manufacturing industry.As a service provider with a major human component there are safety and efficiency issues rather than cost and efficacy,which separates health care from industry.BPR,like other single approaches to improve service quality,are likely to be unsuitable for health care (Shortell and Ferlie,2001),which is comprised of a number of sub processes.It has many stakeholders at different levels and there is wide variation in its internal customer (e.g.,fellow professionals)and external customer (i.e.patients)needs.We accept that BPR can be used as a tool for improving some sub-process or sub-unit activity.An example could be what happened in the LRI where BPR was tried as a quality improvement tool in bed management,pathology and OPD service innovation,etc.;but not applied in areas where clinician’s precision was paramount or where BPR was accepted less-well.In these areas,therefore,views on the methods’suitability forIJHCQA 21,3294quality improvements were mixed.That is,TQM and BPR ideally should always be followed by CQI methods for service improvement to be sustainable and effective.In short,quality management tools designed for industry should be applied to health services with proper selection,caution and care.ReferencesBashein,B.J.,Markus,M.L.and Riley,P.(1994),“Preconditions for BPR success:and how to prevent failures”,Information Systems Management,Vol.11No.2,pp.7-13.Bowns,I.R.and McNulty,T.(1999),Re-engineering Leicester Royal Infirmary–Executive Summary,School of Health and Related Research,University of Sheffield,Sheffield. Devenport,T.and Short,J.(1990),“The new industrial engineering information technology and BPR”,Sloan Management Review,Summer,pp.11-27.DHSS(1984),Health Services Management:Implementation of the NHS Management Inquiry, DHSS Circular HC(84)13,DHSS,London.Field,S.W.and Swift,K.G.(1996),Effecting a Quality Change:An Engineering Approach,Arnold, London.Godfrey,B.(n.d.),“Quality health care”,Quality Digest,available at:/ sep96/health.htm(accessed on15October2006).Grimes,K.(2000),Changing the Change Team,King’s College Hospital,London.Hammer,M.and Champy,J.(1993),Reengineering the Corporation:A Manifesto for Business Revolution,Harper Business Books,New York,NY.Harrison,S.,Hunter,D.,Marnoch,G.and Pollitt,C.(1992),Just Managing:Power and Culture in the NHS,Macmillan,Basingstoke.Harvey,S.and Millett,B.(1999),“OD,TQM and BPR:a comparative approach”,Australian Journal of Management and Organizational Behavior,Vol.2No.3,pp.30-42.Jones,D.and Mitchell,A.(2006),Lean Thinking for the NHS:A Report Commissioned by the NHS Confederation,pamphlet RA395.G7,NHS Confederation,London.Jones,M.(1996),“Re-engineering”,in Warner,M.(Ed.),International Encyclopedia of Business and Management,Routledge,London.McNulty,T.and Ferlie,E.(2000),Reengineering Health Care:The Complexities of Organisational Transformation,Oxford University Press,Oxford.Packwood,T.,Pollitt,C.and Roberts,S.(1998),“Good medicine?A case study of business process reengineering in a hospital”,Policy and Politics,Vol.26No.4,pp.401-15. Shortell,S.and Ferlie,E.(2001),“Improving quality of healthcare in the United Kingdom and the United States:a framework for change”,The Milbank Quarterly,Vol.79No.2,May, pp.281-315.Shortell,S.M.,Waters,T.M.and Clarke,K.W.B.(1998),“Physicians as double agents: maintaining trust in an era of multiple accountabilities”,Journal of the American Medical Association,Vol.280No.12,pp.1102-8.Shutt,J.A.(2003),“Balancing the health care scorecard”,Managed Care,September,pp.42-6. Teng,J.T.C.,Grover,V.and Fiedler,K.(1994),“Business process reengineering:charting a strategic path for the information age”,California Management Review,Vol.36No.3, pp.9-31.wikipedia(2006),“Frederick Winslow Taylor”,available at:/wiki/ Frederick_Winslow_Taylor(accessed2December2006).BPR–saviour or just a fad?295Further reading Davies,H.T.O.(2000),“Organizational culture and quality of health care”,Quality in Health Care ,Vol.9No.2,pp.111-9.Malhotra,Y.(1998),“Business process redesign:an overview”,IEEE Engineering Management Review ,Vol.26No.3,pp.214-25.Pollitt,C.(1996),“Business approaches to quality improvement:why are they hard for the NHS toswallow?”,Quality in Health Care ,Vol.5No.2,pp.104-10.Raymond,L.,Bergeron, F.and Rivard,S.(1980),“Determinants of business processreengineering success in small and large enterprises:an empirical study in the Canadian context”,Journal of Small Business Management ,Vol.36,pp.72-85.Corresponding authorAnjali Patwardhan can be contacted at:doctoranjali@IJHCQA 21,3296To purchase reprints of this article please e-mail:reprints@ Or visit our web site for further details:/reprints。
J. Serb. Chem. Soc. 75 (5) 689–701 (2010) UDC 665.941+547.281+661.717.52–JSCS–3999 12:66.095.26:543.51Original scientific paperdoi: 10.2298/JSC091030036G689Molar-mass distribution of urea–formaldehyde resins of different degrees of polymerisation by MALDI-TOF mass spectrometryIVANA GAVRILOVI Ć-GRMUŠA 1*, OLIVERA NEŠKOVI Ć2,MILANKA ĐIPOROVI Ć-MOM ČILOVI Ć1 and MLA ĐAN POPOVI Ć11Faculty of Forestry, University of Belgrade, Kneza Viseslava 1, 11030 Belgrade and 2Department of Physical Chemistry, Institute “Vin ča” Belgrade,Mike Petrovi ća-Alasa 12–14, 11351 Belgrade, Serbia(Received 30 October 2009, revised 25 January 2010)Abstract : This paper describes some results obtained in an investigation ofurea–formaldehyde (UF) resins of different degrees of polymerisation by ma-trix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) massspectrometry (MS). MALDI-TOF MS proved to be an appropriate techniquefor analyzing these types of polymers, bearing in mind that the results of theanalysis correspond with previous physical and chemical measurements. Thistechnique enables a relatively swift determination of the degree of polymerri-sation through the monitoring of key changes in the structure of a polymer.Thus, in the analysis of UF resins, it may be possible to monitor a decrease inthe intensity of the monohydroxymethyl urea (MMU) signal, which corres-ponds to an increase of the mass spectra values in the mass range of higherhomologues, above 1000 g mol -1. A noticeable difference concerns the signalintensities in the higher mass ranges (up to 1400 g mol -1), which corresponds tomore branched and longer homologues of the polymers. Especially, a signi-ficantly more intensive signal of MMU was registered. The average molecularweight (MW) of the examined samples was between 936 and 1324 g mol -1,with a maximal deviation of 20 %, depending on the ratios of the reactants.Keywords : urea-formaldehyde resins; molar ratio; molecular structure; degreeof polymerisation; MALDI-TOF.INTRODUCTIONUrea–formaldehyde, UF, resins are the most important type of adhesives inthe wood industry. They are widely used for the production of wood-based com-posite panels, such as particleboards, fibreboards and plywood.1* Corresponding author. E-mail: ivana.grmusa@sfb.rs690 GAVRILOVIĆ-GRMUŠA et al.UF resins are based on a manifold reaction of two monomers, urea and formaldehyde.2 By using different reaction and preparation conditions, a more or less innumerable variety of condensed structures is possible.3 In the application stage, UF resins are still soluble or dispersed in water. They also can be supplied in the form of spray-dried water-soluble powders. Such structures consist of li-near or branched polymeric molecules of various molecular masses. After har-dening, UF resins form insoluble three-dimensional networks of thermosetting duromers.4Although UF resins consist of only two main components, i.e., urea and for-maldehyde, they present a broad variety of possible reactions and structures.5 This variety leads to a wide range of molar mass distributions in UF resins, from low molar mass molecules up to more or less polymeric structures. The highest molar masses in UF resin cannot be clearly determined, but it is estimated that molar masses of 100000 to 500000 g mol–1 can successfully describe the macromolecule structure of UF resins.3,6–8From the viewpoint of end-use applications of UF resins, the molar mass distribution is a very important chemical characteristic, having an influence on several important properties of the resin, such as: viscosity, flow ability, pene-tration into the wood surface,9,10 distribution on the wood furnish (particles or fibres), water dilute ability,11etc. The molar mass distribution can be determined by means of gel permeation chromatography (GPC),12 but it is very difficult be-cause an increase in the molecular weight of the soluble macromolecules and in the degree of branching leads to the formation of insoluble products.13 In addi-tion, analysis of the structural components can be performed by various spectro-scopic methods, such as: infrared (IR);14–19 nuclear magnetic resonance (NMR), i.e., 1H-NMR,20–2313C-NMR,14,24–2815N-NMR9,30 and Raman spectroscopy.31Matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry has greatly expanded the use of mass spectrometry towards large molecules and has been demonstrated to be a powerful method for the characte-rization of both synthetic and natural polymers. This technique is usually com-bined with a time-of-flight (TOF) mass analyzer, which has the advantages of being capable of providing a complete mass spectrum per event, having a virtu-ally unlimited mass range, requiring a small amount of analyte and relatively low cost equipment.32–34Generally, the polycondensation structures of UF resins have not been stu-died thoroughly by the MALDI-TOF technique. Therefore, the objective of this research was a MALDI-TOF investigation of the molar mass distribution of UF resin samples obtained from the same reactor batch, but having three different degrees of polymerisations.MALDI-TOF ANALYSIS OF UF RESINS 691EXPERIMENTALPreparation of urea–formaldehyde (UF) resins with various viscositiesUrea–formaldehyde resins were synthesized via the reaction between formalin at a concentration of 47.69 % and urea by DUKOL Ostrava (the Czech Republic). Four samples of about 1 L, designated as I, II, III and IV, were taken from the same reactor batch when the viscosity values showed that different degrees of polymerisation had been attained. Samples I–III were prepared at an F:U molar ratio of 2:1. Sample IV was prepared by modification of sample III by the addition of formaldehyde to give an F:U ratio of 1.45:1. All the samples were kept in a refrigerator before further use.The samples were tested for viscosity, dry matter content, pH value, gel time and pot life. The obtained results are presented in Table I.In order to determine the dry matter content, 2.0 g of resin were dried in a laboratory oven at 105 ± 2 °C until constant mass was reached.The viscosity of the four UF resins was determined by the Brookfield method. The test values registered on the Brookfield instrument together with factors based on the employed combination of the type of rotating spindle and the rotation speed were used to calculate the viscosity in Pa s.The pH value of each UF resin sample was determined by inserting a glass electrode directly into the emulsion.The gel time of the resins containing hardener was determined by the boiling water test. The time measurement began when a test tube containing approximately 2.0 g of resin to-gether with the hardener ammonium sulphate (1 % based on the adhesive dry matter) was immersed into boiling water. The resin in the test tube was gently stirred throughout the test. The gel time was taken as the time elapsed from immersion of the test tube until hardening of the resin, when stirring was no longer possible.The densities of the resins were determined at 20 °C using a pycnometer of 25 mL nominal volume, the exact volume of which was determined using distilled water. Preparation of the MALDI matrixA saturated solution of α-cyano-4-hydroxycinnamic acid (CHCA) was prepared by dis-solving the matrix in 50 % acetonitrile with 0.10 % trifluoracetic acid. The solution was vortexed thoroughly and sonicated in a water bath for several minutes at room temperature. The solution was used for the preparation of samples for MALDI-TOF MS. All employed chemicals were of p.a. purity, originating from Sigma-Aldrich (St. Louis, WI, USA).Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometryAn aliquot of each sample solutions containing an internal standard was combined 1:1 with the CHCA matrix and mixed thoroughly. Aliquots (0.50 μL) of the mixtures were spotted onto a 100-spot sample plate (Applied Biosystems) and air-dried. Mass analysis was performed in the positive ion reflector mode using a 200 Hz frequency pulsed N2 laser operating at 327 nm. Five spectra at each of 10 randomly selected positions were accumulated per spot between 170 and 500 g mol-1 using the MS positive ion reflector mode acquisition method. Calibration of the instrument was realised using Calibration mixture 2 as the external standard. To generate spectra with high mass accuracy, an internal calibration was performed. Sample preparationFor the analysis of silver clusters, 1.0 mg mL-1 solutions in 0.10 % trifluoracetic acid were prepared. 0.50 μL of these solutions was placed onto 0.50 μL of CHCA solution on the target.692 GAVRILOVIĆ-GRMUŠA et al.Data analysisSamples of the UF resins (I–IV) were mixed with the CHCA matrix in ratios of 1:100 and 1:10, v/v. The concentration of CHCA was 10 mg mL-1, diluted in a 1:1 acetonitrile and water solution. After dilution, 0.50 μL volumes of samples were placed on the MALDI plate. Samples were air dried and analyzed on a 4800 Plus MALDI TOF/TOF analyser (Applied Biosystems, Foster City, CA, USA) in the positive mode. Data Explorer, version 4.9, was used for the analysis of the recorded spectra. Ions of the CHCA matrix were used for internal calibration, based on the theoretically calculated masses of CHCA monomers, dimers and trimers at m/z 190.05 (molecular formula C10H7NO3), 379.09 (molecular formula C20H14N2O6) and 568.14 (molecular formula C30H21N3O9), respectively. The mass spectrum of the matrix alone was recorded in order to eliminate the signals generated by the matrix itself. Baseline correction and Gaussian smoothing was applied to each mass spectrum.Positively charged ions were analysed in the reflector mode using delayed ion extraction. The spectra were recorded with a 200 Hz frequency data-sampling rate. Unless otherwise stated, the extraction delay time was 150 ns and deflection was used to suppress ions up to m/z 500. The spectra were recorded using the reflector mode of the TOF analyzer under delayed extraction conditions, thus improving the mass accuracy and resolution. The extraction vol-tage was 20 kV in all cases. Other instrument parameters were tuned for optimal resolution. All instrument high voltages were left on between all analyses to ensure a stable instrument performance. After short interruptions (< 7 min), while exchanging the sample plate, the high voltages of the instrument were switched on 50 min prior to spectra acquisition. The applied laser intensity was between 10 and 30 % of the maximum available laser power.The spectra were acquired without a low mass gate and each spectrum represents an average of at least 100 single laser shots.RESULTS AND DISCUSSIONPhysical characteristics of UF resinsThe characteristics of UF resins (Table I) showed no significant differences between samples I–III, except for the viscosity, sample III having a viscosity of 555 mPa s, while the viscosities of samples I and II were 218 and 281 mPa s, respectively. All the determined physical properties were significantly increased for sample IV in comparison to the other samples, which clearly distinguishes sample IV from samples I–III. The viscosity of sample IV was 2052 mPa s, a value 3 to 9 times higher when compared with the other samples. It will be quite evident later that increased content of higher homologues increased the viscosity of this resin.TABLE I. The characteristics of the UF resins (Samples I–IV)No. PropertyUF SampleI II III IV1 Drymatter,% 53.7 53.6 53.8 65.62 Brookfield viscosity (at 20 °C), mPa s 218 282 555 20523 pH 7.8 7.9 8.0 7.74 Gel time, s 58 59 58 595 Density, g cm3 1.24 1.24 1.25 1.30MALDI-TOF ANALYSIS OF UF RESINS 693Degree of polymerisationThe recorded spectra of samples I–IV (Figs. 1 and 2), obtained on the MALDI-TOF/TOF instrument, implicate a close relationship between viscosity, dry matter content and degree of polymerisation of the UF resin samples. A com-parison of spectra revealed sample I had the lowest degree of polymerisation and also the lowest viscosity.Fig. 1. MALDI-TOF Mass spectra of samples I and II in the m/z range 561–953.Results of the analysis showed that samples I and II had similar degrees of polymerisation, but with a slightly higher amount of branching in sample I, as in-dicated by its more pronounced mass signals in the m/z range 561–953 (Fig. 1). Although, both samples had a similar dry matter content, they differed in visco-sity, with sample II having an approximately 30 % higher viscosity than sample I.Due to its higher viscosity, an increased amount of homologues with a high-er degree of polymerisation is to be expected in sample II. However, the differ-rence between the signal intensity of the higher homologues in samples I and II was negligible (also when compared with samples III and IV).The dry matter content of samples I, II and III were similar. On the other hand, the viscosity of sample III was almost twice that of samples I and II. A higher viscosity implies a higher degree of polymerisation, which can be observed in the mass spectrum of sample III, shown in Fig. 2.In addition, three times more intense signals in the same mass range of the higher polymerisation homologues were registered for sample III (data not given) than for samples I and II (shown in Fig. 1).694 GAVRILOVIĆ-GRMUŠA et al.According to its physical and chemical parameters, sample IV had no simi-larities with samples I–III, having an almost one order of magnitude higher vis-cosity compared with the other three samples, a 10 % higher dry matter content and a significantly increased degree of polymerisation of higher homologues, as shown in Fig. 2.Fig. 2. MALDI-TOF Mass spectra of sample III (maximum registered polymer mass1052 g mol-1) and sample IV (maximum registered polymer mass 1324 g mol-1).Comparison of the polymer structures of samples I, II, III and IVHigher homologue products of the polymerisation processes, which are re-gistered in the m/z range 200–1200, may be described through a combination of the residues in the general structure. Confirmation of such structures was basedMALDI-TOF ANALYSIS OF UF RESINS 695 on both external and internal calibration. The external calibration was applied on the mass spectra shown in Figs. 1 and 2, with an experimental error of 0.10 g mol–1 of the mass value. In addition, the mass spectra were internally calibrated (see later in the text Figs. 5–7) using signals originating from the ions of the CHCA matrix, which increased the mass measurement accuracy to 5 ppm (third of the four decimal digits of the mass value). Accurate mass measurement leads to a better determination of the elemental ion composition and, in this sense, the molecular formula of a link can be established. As the polymers consisted of a series of links, it was impossible to determine the molecular formulas of all the polymers. However, it was possible to determine the constitutive elements of the polymer structure.The true mass and molecular formula were determined using the signals of the highest intensity in order to identify the structure of the higher homologues. Within the observed mass range and according to the signal intensity, it is pos-sible to determine the type of homologue and the preferred form of branching. NMR research indicated that the formation of mono-, di- and tri-hydroxymethyl urea under alkaline conditions amounts to 45–60 % and partial polymerisation to dimethyl ethers to 10–20 % (i.e., –NH–CH2OH 45–60 % and –N(CH2OH)2 10–15 %).35 In addition, 10–15 % of the formaldehyde remained unreacted. The for-mation of methylol groups mostly depended on the F/U molar ratio, with higher molar ratios increasing the tendency to form highly methylolated species.36,37 The significant intensive signal of MMU can be seen at m/z 91 in the MALDI-TOF mass spectra of samples I–IV shown in Fig. 3. Some examples of polymer chains of ether homologues are demonstrated in Figs. 4 and 5, from which, it is possible to determine the representative type of molecular structure originating in the branching process and growth of the polymer chains. This might reveal if the method of synthesis favours the creation of ether or methyl bonds and, furthermore, allow an estimation of the preferred number of hydroxyl groups per number of carbons in the chain. As expected, the highest MMU intensity of 68,000 was registered for sample I, in comparison to sample IV, with an MMU intensity of 22000. Contrary to sample IV, which had an increased ratio of higher homologues, sample I had increased amounts of simple MMU structures, 3.1 times higher when compared to sample IV, suggesting poor branching in sample I and a high degree of polymerisation of sample IV. The relations between sam-ples II and III were similar to those of samples I and IV. Thus, sample III had a higher ratio of higher polymer structures in comparison to sample II, while sample II had a 2.7 times more intensive MMU signal when compared to sample III.Structures A, B and C shown in Fig. 5 may also belong to structures with hydroxymethyl groups with secondary and tertiary amines in different positions. Thus, the molecular formulas of structures A C8H18N4O5, B C9H20N4O6 and C C10H22N4O7 would have to be preserved. Mass spectra showing the intensity of the structures A, B and C are shown in Fig. 6.696 GAVRILOVIĆ-GRMUŠA et al.Fig. 3. MALDI-TOF Mass spectra of samples I–IV, with a significant intense signal ofmonohydroxymethylurea (MMU) at m/z 91.MALDI-TOF ANALYSIS OF UF RESINS 697Fig. 4. Molecules formed through reaction of urea and formaldehyde under alkaline conditions, registered in the m/z range of 250–312.698 GAVRILOVIĆ-GRMUŠA et al.Fig. 5. Molecules formed through reaction of urea and formaldehyde under alkaline conditions, registered in the m/z range of 250–312. The associated theoreticalm/z values for structures A, B and C are 251.14, 281.14 and 311.16, respectively.The mass spectrum of sample IV for the selected region is shown in Fig. 6. Identical mass spectra were obtained for samples I–III. According to the signal intensity of the ion structures A, B and C, it may be concluded that the homo-logues containing ether bonds are more abundant than those of homologues with methylene bonds are. It may also be concluded that the most intensive signals in the spectra belong to structures with terminal di- and tetrahydroxymethylene groups (structures A and C). The calculation of molecular formulas in regards to theFig. 6. MALDI-TOF Mass spectra of sample IV with the A, B and C structures designated.MALDI-TOF ANALYSIS OF UF RESINS 699 measured molecular masses for structures A–C were possible because a maxi-mum measurement error of 5 ppm was achieved.Methylene bridges, branching polymer structures, are present over the whole spectrum and signify the difference between peaks of 12 g mol–1 or 12.0072 g mol–1 as measured and shown in Fig. 7.Fig. 7. MALDI-TOF Mass spectrum of sample IV with noticeably constant differences of 12 g mol-1 between the most intensive signals in the spectrum.CONCLUSIONSThis paper describes some results obtained in an investigation of urea–for-maldehyde (UF) resins of different degrees of polymerisation by MALDI-TOF mass spectrometry. Each of the four samples gave a contribution to the eluci-dation of the establishment of the molar masses of the resins. The interpretation and combination of the results led to following conclusions:1) The average MW of the examined samples I–IV of UF resin was between 936 and 1324 g mol–1, with a maximal deviation of 20 %, depending on the ratios of the reactants.2) The signal intensities and their positions regarding samples I–IV showed no differences. The only noticeable difference concerned the signal intensities in the higher mass ranges (up to 1400 g mol–1), which corresponds to more branched and longer homologues of the polymers.3) Sample IV had, by far, the highest degree of branching and polymerisa-tion when compared to samples I–III, which was evidenced as it was the polymer giving the highest recorded mass of 1324 g mol–1 and multiple higher signal in-tensities in the m/z range of 250–1000.4) MALDI-TOF proved to be an appropriate technique for analyzing these types of polymers, bearing in mind that the results of analysis corresponded with the results of physical and chemical measurements (dry matter content, viscosity,700 GAVRILOVIĆ-GRMUŠA et al.gel time, etc.). For routine polymer analysis, this technique enables a relatively swift and simple determination of the degree of polymerisation, through the mo-nitoring of key changes in the polymer structure. It may be possible to monitor a decrease in the intensity of the MMU signal, which corresponds to an increase of the mass spectra values in the mass range of higher homologues, above 1000 g mol–1.Acknowledgements.The research work presented in this paper was financed by the Mi-nistry of Science and Technological Development of the Republic of Serbia, Project “Wood biomass as a resource of sustainable development of Serbia”, 20070-TP.ИЗВОДРАСПОДЕЛАМОЛАРНЕМАСЕУРЕА–ФОРМАЛДЕХИДНИХСМОЛАРАЗЛИЧИТОГСТЕПЕНАПОЛИМЕРИЗАЦИЈЕОДРЕЂЕНАМАСЕНОМСПЕКТРОМЕТРИЈОМ MALDI-TOFИВАНАГАВРИЛОВИЋ-ГРМУША1, ОЛИВЕРАНЕШКОВИЋ2, МИЛАНКАЂИПОРОВИЋ-МОМЧИЛОВИЋ1ИМЛАЂАНПОПОВИЋ11[umarski fakultet, Univerzitet u Beogradu, Kneza Vi{eslava 1, 11030 Beograd i 2Laboratorija za fizi~ku hemiju, Institut“Vin~a”, Mike Petrovi}a-Alasa 12–14, 11351 Beograd Уциљукарактеризацијечетириузоракауреа–формалдехидне (УФ) смоле, коришћенајеметодамасенеспектроскопије MALDI-TOF (матрицомпотпомогнуталасерскадесорп-ција/јонизација-времепрелета). Каоједанодвидоваанализеполимера, поменутатехникаомогућујерелативнобрзоодређивањестепенапилокондензацијепутемпраћењакључнихпроменауструктуриполимера. ПрианализиузоракаУФсмолеутврђено je дасмањењеин-тензитетаММУсигналаодговараповећањувредностимасеногспектрауопсегувишиххо-мологаизнад 1000 g mol-1. Значајнаразликаодносисенаинтензитетсигналапривишеммасеномопсегу(до 1400 g mol–1), штоодговараразгранатијимидужимполимернимхомолозима. СредњаМwиспитиванихузораканалазисеуопсегуод 936 до 1324 g mol–1, самаксималномдевијацијомод 20 % узависностиодкомпоненти.(Примљено 30. октобра 2009, ревидирано 25. јануара 2010)REFERENCES1.M. Dunky, A. Pizzi, Wood adhesives, in Adhesion Science and Engineering –2. Surfaces,Chemistry and Applications, Amsterdam, 2002, p. 10392. A. Pizzy, Wood Adhesives, Chemistry and Technology, Marcel Decker Inc., New York,19833.M. Dunky, In Proceedings of 5th Pacific Rim Bio-Based Composites Symposium,Cambera, Australia, 2000, p. 2054.M. Dunky, Int. J. Adhes. 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