Abstract—We use simulations to investigate the influence of the value of the differential delay of the Mach-Zehnder interferometer (MZI) demodulator in differential phase-shift-keyed (DPSK) systems when the system is limited by the combined effect of chromatic dispersion and in-band crosstalk. It is found that the dispersion and filtering tolerance improvement which is realized when the delay is less than one bit-period is preserved in systems with strong in-band crosstalk.
Index Terms—Differential phase-shift keying (DPSK), Linear crosstalk, Mach-Zehnder interferometers (MZI), optical networks.
I.I NTRODUCTION
HE need for very high transmission capacity at a lower cost per bit has attracted considerable interest in the use of the differential phase-shift keying (DPSK) modulation format in dense wavelength division multiplexing (DWDM) systems. In particular, for per channel rates of 40 Gbps and beyond, with channel spacing of 50 GHz, DPSK is an attractive modulation format due to its superior OSNR sensitivity and better nonlinearity tolerance compared to ON-OFF-keying (OOK) formats [1].
The conventional DPSK receiver with a balance detector has exactly one bit period delay between the two arms in the asymmetric Mach-Zehnder (AMZ) interferometer filter. We will refer to this setup as classical DPSK (CDPSK) in this paper [2]. Any mismatch in the differential delay, τ, between the two arms due to design or receiver imperfection gives a corresponding change in the free spectral range (FSR), 1/τ, of the AMZ filter transfer function [3,4,5]. When the differential delay is less than the bit period, it results in what is called “partial” DPSK (PDPSK) [2-5]. At the output of the PDPSK demodulator, a single bit will interfere with its adjacent bit and partly with itself. The partial bit self interaction leads to a constant deterministic constructive interference at the receiver, providing a buffer between bits which ultimately improves the inter-symbol interference (ISI) tolerance [5].
Manuscript received June 14, 2010.
Dwight Richards is with the College of Staten Island, CUNY, Staten Island, NY, 10314 USA (e-mail: dwight.richards@https://www.doczj.com/doc/582256397.html,).
Sriharsha Kota Pavan, Jigesh Patel, and Enrico Ghillino are with RSoft Design Group, Inc., Ossining, NY, 10562, USA.
Ordinarily, we would expect the less than one bit delay to impose a performance penalty, and this is indeed the case in a channel with no dispersion or filtering degradation; however, it has been shown that a PDPSK receiver can improve performance when the transmitted signal is of a high bit rate over a channel which employs narrowband optical filters, or if the signal experiences significant dispersion [2]. While CDPSK has excellent OSNR sensitivity, it does not possess the filtering tolerance that is needed in a large network deployment with several stages of filter elements, and it can also suffer significant degradations as a result of chromatic dispersion generated by either the transmission fibers or the filter elements in the network nodes [2, 5].
Though chromatic dispersion and the effects of self-filtering can be detrimental in high bit rate systems, they are by no means the only degrading effects that concern network designers. Linear crosstalk, and in particular, in-band coherent crosstalk, can be troublesome. In-Band crosstalk, also known as homodyne crosstalk, is the crosstalk within the same wavelength slot as the signal of interest. It cannot be removed by an optical filter; therefore, it accumulates as more network elements are traversed. The performance penalty from in-band crosstalk is worst when the polarization states of the main signal and the offending crosstalk signal are aligned (i.e. co-polarized). In general, interfering signals will be randomly polarized due to different amounts of polarization mode dispersion (PMD) from the different paths in the network and also due to the interaction between polarization and nonlinearity [6]. Whereas there are studies which have enumerated the effects of chromatic dispersion, filtering tolerance and in-band crosstalk in DPSK systems, we believe that it is also important to explore the performance from a real system perspective where all the degrading effects are simultaneously at play. Such an analysis allows for the evaluation of the system performance in the presence of multiple impairments which may interact in unpredictable ways.
In this paper, we use simulation studies to investigate the combined effect of in-band crosstalk and chromatic dispersion in a DPSK system. Our goal is to see if the advantages of PDPSK with respect to dispersion and filter tolerance, as mentioned above, are preserved, improved, or deteriorate
Improved Tolerance to the Combined Effect of In-Band Crosstalk and Chromatic Dispersion in
Partial DPSK Systems
Dwight Richards, Member, IEEE, Sriharsha Kota Pavan, Member, IEEE, Jigesh Patel, Senior Member,
IEEE, and Enrico Ghillino
T
2010 15th IEEE International Workshop on Computer Aided Modeling, Analysis and Design of Communication Links and Networks (CAMAD)
when strong in-band crosstalk is also affecting the high bit rate signal. The performance metric used in our OptSim TM[7] system simulations is based on the Karhunen-Loeve (K-L) expansion semi-analytical BER estimation technique [8]. Section II describes the schematic layout and justifies the use of the K-L semi-analytical BER estimation technique by comparing it to the more general and rigorous direct error counting method. In Section III we present our simulation results and finally, in Section IV we present our conclusion.
II.S IMULATION SETUP
A.Schematic Layout
The schematic layout is shown in Fig. 1. The NRZ DPSK signal is generated by sending a 212– 1 pseudorandom bit sequence at 43 Gbps to an NRZ electrical driver. The driver encodes the “0” level at -5V and the “1” level at +5V. The signal from the driver is then sent to a lowpass Bessel filter with a 3 dB bandwidth equal to the bit rate. The number of samples per bit is 61. A CW laser signal centered at 193.9 THz, with a full width at half maximum (FWHM) linewidth of 10 MHz and a power of 5 dBm is modulated by the electrical signal using a Mach-Zehnder modulator. The modulated signal is passed through an optical Bessel filter, which represents an optical multiplexer module, with a 3 dB bandwidth of 50 GHz centered at the laser wavelength. The signal is then split equally into two paths, one being the main signal path (upper) and the other (lower) to serve as the source of our in-band crosstalk. The crosstalk path consists of a polarization scrambler, which randomizes the polarization state of the crosstalk relative to the main signal. As noted before, this randomization of the relative polarization states of interferers is representative of real systems, but does not replicate experiments that explicitly co-polarize the interfering signals to emulate the worst possible case of signal and crosstalk interaction [9, 10]. Therefore, our simulation represents the more common case in real applications rather than the absolute worst-case scenario. The crosstalk path also includes an attenuator model to control the power of the in-band crosstalk signal and a 5 km length of optical fiber to decorrelate the interference pattern with the main signal pattern. The signal and crosstalk are then combined at a lossless optical combiner before the combined signal is sent to an optical fiber Bragg grating which has a reference frequency at the laser center wavelength and allows us to simulate varying amounts of chromatic dispersion of the combined optical signal.
At the receiving end, we have an optically amplified DPSK receiver with balanced detection. There is an optical Bessel filter, which represents the demultiplexer, with similar parameters as the multiplexer module. The optical power entering the differential receiver is set to 6 dBm. Both arms of the balance receiver use PIN diodes with equal responsivities of 1A/W. The delay imperfection in the receiver is specified by the Mach-Zehnder Delay mismatch parameter as a percentage of the bit period. The K-L semi-analytical BER estimation technique, to be discussed in the next section, was
used to calculate the BER at the receiver. To evaluate the combined effect of in-band crosstalk and dispersion, we simulated three values of τ: (1) τ equal 100% (CDPSK) of the bit period (FSR = 43 GHz), (2) τ equal 86% (86-PDPSK) of the bit period (FSR = 50 GHz) and (3) τ equal 65% (65-PDPSK) of the bit period (FSR = 66 GHz) [2]. We varied the value of the crosstalk from a high of -2 dB to a low of -22 dB.
B.BER Estimation Technique
As noted above, the K-L semi-analytical BER estimation technique was utilized in our simulations. This technique is extremely computationally efficient compared to direct counting of errors, and as shown in Fig. 2, there is a very good agreement when we superimpose plots of BER versus OSNR obtained using both techniques. The K-L results were obtained by simulating a mere 511 bits (we used 700 bits for the crosstalk study) while the direct error counting results were obtained by simulating 300,000 bits. Also, the range of OSNR was selected such that the BER was high enough to be directly counted within a practical timeframe over 300,000 transmitted bits. The deviation in BER at an OSNR of 17.5 dB in Fig. 2 is due to a less than sufficient number of transmitted bits for direct counting of errors as the estimated BER gets low. Direct error counting requires a large number of transmitted
Fig. 1. Simulation schematic of in-band crosstalk
bits and hence an extremely long simulation time, especially if the BER to be counted is expected to be very low.
III.R ESULTS AND DISCUSSION
To quantitatively assess the in-band crosstalk induced OSNR penalty, we measured the BER at different crosstalk levels for the CDPSK, 86-PDPSK, and 65-PDPSK cases, using a common baseline pre-FEC BER of 10-5, calculated for the impairment-free channel (i.e. no dispersion and no crosstalk). Fig. 3 shows the OSNR penalty as a function of crosstalk level for the case when there is no dispersion in the system (0 ps/nm). We can clearly see that as the power of the crosstalk is increased, the OSNR penalty also increases in all three cases. This is consistent with the trend observed experimentally in [9, 10]. We observed a slight variation in the OSNR penalty calculations for the three cases examined, but we believe that this is of no significance and can be attributed to simulation accurarcy, which is on the order of 0.25 dB.
We then turned our attention to the case of a highly dispersive channel where in-band crosstalk also affects the signal quality. Fig. 4 shows the OSNR penalty as a function of in-band crosstalk for a total dispersion of 160 ps/nm, representing 10 km of standard single-mode fiber (SMF), assuming a fiber dispersion of 16 ps/nm/km. Once again, the OSNR penalty gets worse with increasing levels of crosstalk as expected, but now, we also observed a meaningful separation of the OSNR penalty among the three FSR values under study. We can clearly see that the OSNR penalty induced by in-band crosstalk is worst for the CDPSK case and best for the 65-PDPSK case, with the 86-PDPSK penalty in the middle. This trend is consistent with the improvements of both dispersion and filter tolerances observed for PDPSK, as shown in [2-5]. In our case, we believe the improved performance is due to the excellent disperson tolerance offered by PDPSK and not due to any advantage that PDPSK has over CDPSK in terms of in-band crosstalk tolerance. Moreover,
since the DPSK format encodes the information in the phase of the signal and the in-band crosstalk causes phase mismatched-induced fluctuation of power, it is intuitive that all forms of DPSK will be affected in a similar way. The good news is that the advantages of PDPSK relative to CDPSK do not deteriorate in the presence of in-band crosstalk. This is an important result since PDPSK offers real advantages for high bit rate systems with high dispersion and strong optical filtering.
Having concluded that the superior performance of PDPSK compared to CDPSK, in presence of both disperson and in-band crosstalk, is primarily due to the improved dispersion tolerance that PDPSK offers, we proceeded to explore the influence of the MZI delay mismatch in a high bitrate dispersive channel. We based this new investigation on the schematic layout shown in Fig. 5. A 40 Gbps NRZ DPSK signal is generated and sent to the RZ pulse carver at the transmitter [11]. Note that the RZ format inherently has a dispersion tolerance advantage compared to NRZ format [5]. As was the case in the previously discussed system, the fiber dispersion is modeled by an ideal fiber Bragg gating. The delay imperfection in the receiver is specified by the Mach Zehnder delay mismatch parameter as a percentage of the bit
Fig. 3. OSNR penalty as a function of in-band crosstalk for the no
dispersion case Fig. 4. OSNR penalty as a function of in-band crosstalkwithr160 ps/nm (10 km SMF) of dispersion
Fig. 5. RZ-DPSK schematic for AMZ delay mismatch-dispersion
study
period in the K-L BER estimator model.
Fig. 6 shows the calculated BER as a function of AMZ delay mismatch when the total chromatic dispersion is 80 ps/nm. The AMZ delay mismatch was varied from -30% to 30% in steps of 5%. Clearly, a delay mismatch of one bit or less (i.e. CDPSK and PDPSK) gives better performance than a delay mismatch of more than one bit [5, 12]. A more interesting observation is that in the presence of chromatic dispersion, the optimum BER performance does not correspond to a zero mismatch (i.e. CDPSK) in the AMZ delay. These results are consistent with those obtained experimentally in [2, 4] and numerically in [5].
We then turned our attention to investigating how the optimum BER is affected by the AMZ delay mismatch in the presence of varying levels of dispersion. To accomplish this, we modified the schematic layout in Fig. 5 to create five cases with different dispersion values set at 0 ps/nm, 60 ps/nm, 80 ps/nm, 100 ps/nm, and 120 ps/nm, respectively. For each case, the OSNR was varied and a family of plots was obtained by
plotting BER vs OSNR as a function of AMZ delay mismatch. Figures 7 and 8 show the BER plots for the cases of 0 ps/nm and 120 ps/nm dispersion, respectively. For simplicity, we only show the curves for AMZ delay mismatches of 100% (CDPSK) and 70% (70-PDPSK), respectively. In particular, Fig. 7 shows that in the absence of dispersion and other impairments (i.e. back-to-back system), CDPSK provides more than 1 dB in OSNR sensitivity improvement compared to 70-PDPSK, over a wide range of BER values. On the other hand, as shown in Fig. 8, in the presence of dispersion equivalent to approximately 7.5 km of SMF, 70-PDPSK
Table 1. The OSNR values at 10-3 BER for each AMZ delay mismatch for different runs at the different dispersion
values
Fig. 7. BER vs OSNR for back-to-back system (no impairments) with CDPSK (lower curve) and 70-PDPSK (upper curve)
receivers.
Fig. 8. BER vs OSNR for the system with 120 ps/nm dispersion (7.5 km of SMF) with CDPSK (upper curve) and 70-PDPSK (lower
curve) receiver.
BER of 10-10. The complete set of BER results were then used to obtain OSNR penalties for a target pre-FEC BER of 10-3. Table 1 shows the OSNR values at 10-3BER for each AMZ delay mismatch at the different dispersion values. The difference between the OSNR at a BER of 10-3 for each case and the OSNR obtained at zero mismatch, and zero dispersion for the same BER gives the OSNR penalty at a BER of 10-3, which is plotted in Fig. 9. From Fig. 9, we can clearly see that in the presence of increasing values of dispersion, the optimal AMZ delay mismatch shifts to the left, indicating that PDPSK with decreasing differential delay or correspondingly, an increasing FSR of the AMZ, provides improved OSNR penalty performance. This observation is consistent with numerical results shown in [5].
IV.C ONCLUSION
In optical networks with high bit rate signals and many filtering elements, in-band crosstalk and dispersion will combine to limit overall system performance. We used simulation to show that the improved tolerances to dispersion and strong optical filtering provided by PDPSK systems compared to CDPSK systems are not compromised by the combined effect of dispersion and in-band crosstalk. In addition, we explored the relationship between the AMZ bit delay mismatch and the amount of dispersion in a system by comparing the OSNR penalty at a pre-FEC BER of 10-3, confirming the inherent benefits of PDPSK.
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Fig. 9. OSNR penalty plot for different values of dispersion as a function of % AMZ bit delay mismatch.
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第十章英语童谣、歌曲教学的意义和作用 第一节英语童谣、歌曲教学的意义和作用 人类在漫长的历史过程中，随着语言的产生和发展形成了一个精细而复杂的发声器官，不仅能说话，而且会唱歌。唱歌是人类自然的愿望，是人类表达自己喜、怒、哀、乐各种复杂感情的有力手段。唱歌、念童谣在儿童生活中也同样有着极重要的意义，也是儿童表达自己喜悦、兴奋、激动的一种方法，是他们显露自己能力的心理状态的反映。在每个人的童年记忆中，总对一些充满情趣、合辙押韵、朗朗上口的歌谣记忆犹新，诸如：“小鸭、小鸡”、“丢手绢”、“读书郎”、“小画家”等，这些童谣和儿歌天真活泼，节奏感强，积极向上，富有教育性和知识性，正合少年儿童的心理与口味。可以说，童谣和儿歌是孩子的亲密伙伴，有孩子的地方总能听见那欢乐、柔嫩、清脆的天真童声。 童谣是符合儿童年龄特点的、有韵脚、有意境、有节奏、充满童趣、朗朗上口的一种说唱形式。儿童歌曲比童谣更具音乐性。说歌谣、唱歌曲对儿童语言发展所起的作用是不可低估的。音乐和节奏是儿童学习语言的重要组成部分。一般来说，歌词容易记牢。一首好的歌词往往是一首好的儿歌，尤其是少儿歌曲的歌词更像是一首上口的童谣，儿童在学唱歌的过程中，最先学会的是歌词。也就是说，儿童在学习歌曲的同时就学习了一首好的儿歌，无形中词汇量、艺术性语言就能有所增加。同样，没有曲调但节奏鲜明的童谣也是训练儿童语言节奏感的绝佳材料。 在小学英语教学中，使用英文童谣和歌曲教授英语，符合小学生的年龄特点，有利于他们学习英语。音乐与语言二者都有句子、韵、重音和重复。曲调中有些强弱快慢的变化就是来自于人们的语言，经常说唱英文童谣、儿歌能使小学生对英语的重音、节奏、句子的结构等加强掌握与理解，如善于辨别英语的发音，掌握其重音、节奏、语句、语调等，因为唱歌时要求吐字清楚，这对培养小学生正确发音有很大帮助。学习英文童谣和歌曲除了能帮助儿童学习英语语音和节奏，也可以学习、巩固语法与词汇，而最重要的是能提高英语学习的兴趣。让学生在拍拍手，说说童谣，唱唱歌，做做游戏中不知不觉地打好学习英语的基础。 第二节英语教学中童谣、歌曲的选择 童谣是符合儿童年龄特点的、有韵脚、有意境、有节奏、充满童趣、朗朗上口的一种说唱形式。儿童歌曲比童谣更具音乐性。两种形式都有词，且符合儿童的年龄特征，故作为一种辅助教学手段在小学英语教学中占有重要的地位。拍拍手，说说童谣，唱唱歌，做做游戏，在不知不觉中也打好了学习英语的基础。应该说，念英文童谣、唱英文歌是学习英语行之有效的好办法。那么如何选择儿童感兴趣的、富有教育意义的、适合儿童说唱的、对英语教学有一定辅助作用的英文童谣和歌曲呢？ 一、内容应有趣并为小学生所理解 小学生在小学虽说有了一定的母语基础，完成了母语的掌握过程，但对英文还处于低幼儿阶段。用英文理解事物的能力在低年级几乎没有，到中高年级也还不高。因此，英文童谣或歌曲使用的单词应生动形象，歌词在语言上不宜太深，最好浅显易懂，要能听得清楚，为小学生所理解。否则他们只会机械地发出声音，并不知其含意，也就难以引起相应的心理活动。
墙纸常用标识大全，你都认识吗？ 我们在选购墙纸的时候，常常会在版本背面或底页看到各种墙纸标识，这些标识代表这这款墙纸的特性、功能甚至铺贴方式，直接影响这我们今后对这款墙纸的使用。今天小编就给大家做一个这方面的普及。
RAL壁纸质量认证体系 考虑到环境的承受能力，同时满足消费者的最高需求，1991年，60多个墙纸生产商共同决定成立联合组织对产品实行持续监管。在与不同研究所和行政机关的共同合作下，严格、全面的产品规定终于被确立，这些规定远严格于法律规定。满足所有规定的产品可以使用RAL标识来标志。在Braunschweig的Frauenhofer研究所负责中立的监督所有产品规定的履行。只有那些满足高要求的产品有权利使用RAL标志。 RAL是墙纸产品质量的保证，同时也意味着对人体健康无危害，因为这些产品在生产过程中： 1.印刷色浆的色素中不含重金属、不含氟氯碳氢； 2.定形剂中不含铅和镉； 3.不含氯化溶剂以及带香料的溶剂； 蓝天使环保标识 德国的环境标志认证制度起源于1978年，由联邦政府内政部长和各洲环境保护部部长共同建立，亦称“蓝天使”标志认证。作为世界上最古老的环境标志，目前已有80种产品类别的10000个产品和服务拥有了蓝天使标志，其中17%的产品来自国际市场，在国际市场具有很高的市场认知度。德国蓝天使标志隶属于德国联邦环保局、自然保护部和核安全部，由联邦环保部门、质量和产品认
证委员会（RAL）德国协会共同发起，所有受理产品和服务的技术标准均由独立的环境标志委员会来决定，其认证主要通过文件审核依据标准的检测报告和企业自我声明的形式来进行。
英语经典儿歌 1.ABCsong 2.Do- Re- Mi 3.Ten little Indians 4.Head and shoulders knees and toes 5.Apple round 6.Old Macdonal 7.Jingle bell 8.Happy New Year 9.Are you sleeping? 10.Day of the Week 11.Eight Little Baby Ducks 12. If you are happy 13.Edelweiss（雪绒花） 14.Twinkle, twinkle, little star 15.Two Little Blackbirds 16.We Wish You A Merry Christmas 17.Mary Had a Little Lamb 18. London Bridge is Falling Down 19.Colours 20. I can sing a rainbow
部分歌词 1. ABC Song （字母歌） come together, come to me while I sing the ABC. ABCDEFGHIJKLMNOPQ RS and TUVW and XYZ. Now you ve heard my ABC. Tell me what you thin k of me. A B C D E F G H I J K L M N L P Q R S and T U V W and X Y Z. now you ve heard our ABC. Let us hear your ABC. All together sing with me. Le t us try our ABC. A B C D E F G H I J K L M N O P Q R S and T U V W and X Y Z. now you ve heard our ANC. Let us hear your ABC. Do-Re-Mi（哆－来－咪） Doe a deer a female deer. Ray a drop of golden sun. me a name I call my self, Far a long long way to run. Sew a needle pulling thread. La a note th at follow sew. Tea a drink with jam and bread. That will bring us back to doe, oh oh oh, Doe ray me far sew la tea doe. Sew, doe. Day of the Week（星期之歌） Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday. (Re peating 3 times.) Are You Sleeping?（你睡了吗） Are you sleeping, are you sleeping? Brother John, brother John. Morn
1..Hello song 歌词(Lyrics) Hello, hello, hello how are you? I'm fine, I'm fine , I hope that you are too. Hello, hello, hello how are you? I'm fine, I'm fine , I hope that you are too 2.. Finger Family 歌词Lyrics Daddy finger, Daddy finger, where are you? Here I am. Here I am. How do you do? Mammy finger, Mammy finger, where are you? Here I am. Here I am. How do you do? Brother finger, Brother finger, where are you? Here I am. Here I am. How do you do? Sister finger, Sister finger, where are you? Here I am. Here I am. How do you do? Baby finger, Baby finger, where are you? Here I am. Here I am. How do you do? 3..《ABC song》歌词 A B C D , E F G H I J K , L M N O P Q R S , T U V W X Y Z Now I know my ABC, tell me what you think of me 4.. Twinkle Twinkle Little Star 歌词 Twinkle, twinkle, little star, How I wonder what you are. Up above the world so high, Like a diamond in the sky. Twinkle, twinkle, little star, How I wonder what you are! When the blazing sun is gone, When there's nothing he shines upon, Then you show your little light, Twinkle, twinkle, all the night.
英文童谣儿歌汇总
Chants （1）“Hello,hello,how are you?”Hello, hello, how are you? Fine, fine,thank you. Hello, hello, how are you? Oh, oh,just so so. （2）“One—ten ” One,one,one,everybody run. Two,two,two,tie your shoe. Three,three,three,look at me. Four,four,four,fall on the floor. Five,five,five,jump up high. Six six six ,clap your hands. Seven seven seven,reach to the heaven. Eight eight eight,stamp your feet. Nine nine nine,turn around. Ten ten ten, please sit down. （3）“One—five” One one one a little dog run Two two two cats can see you Three three three birds in the tree Four four four rats on the floor Five five five what’s the time? （4）“One—ten” One is worm go go go Two is rabbit jump jump jump Three is cat miao miao miao Four is crab move move move Five is bird fly fly fly Six is ox walk walk walk
墙纸广告语大全 本文是关于墙纸广告语大全，仅供参考，希望对您有所帮助，感谢阅读。 墙纸是一种万能的东西，装修不满意贴，墙脏了贴，颜色不满意了贴，贴贴贴~【墙纸广告语大全】买了好多都没有来的及贴。1、臻美墙纸，家的选择。 2、蔷薇花，墙文化! 3、墙美，家美，生活美——小壁虎墙纸。 4、“纸”要你多姿生活历久弥新! 5、墙纸用锦碧，辉煌金碧! 6、映画生活，映画我家，好生活，不褪色。 7、表里如意展花样，格调魅力梦春天! 8、贴近生活，信赖墙纸。 9、美丽生活“纸”因有你——粉蔷薇墙纸。 10、清雅闲居，墙壁艺术贴近生活。 11、让墙自由呼吸…… 12、居加，为家点睛。 13、居加，是一道生活风景。 14、居加，是一种生活内容。 15、居加好，壁纸好! 16、为生活加道风景。 17、居加，个性之家。 18、Dream houseonly homecplus! 19、居加，生活家。 20、居加，绘出精彩。 21、Ihave dream houmeplus! 22、居加，加一道风景，加一点灵动。 23、居加，家适。 24、释放自我，唯我居加;无限领绘，自然居加。 25、家居添色彩，壁丽您最爱。
26、美丽环绕我的家。 27、给墙壁穿上美丽的衣服。 28、美壁墙纸，优质您的生活。 29、墙纸，墙纸，如墙之子。 30、墙壁会表情，哪张适合你? 31、只要你有墙，我就有纸。 32、女人花如泪，墙上花如你。 33、艺术让你选择了***，铺设幸福生活。 34、时尚不失大方，简易不失舒适。 35、图墙壁纸，奋发图强! 36、墙纸用美家，美丽我们的家。 37、居加，创意在家居。 38、世上无难事，只要有居加。 39、居加，绘生活。 40、为生活加点氧。 41、居加，真个性，好品质。 42、居加，加点个性，加点艺术。 43、我们是墙面的雕刻师。居加，你的个性之家。 44、Just homeplus! 45、居加壁画，家的童话。 46、清雅优居，加的选择。 47、居，加色彩，绘生活。 48、居加，我们从新开始。 49、实而不俗，美而不腻，居而不愁。加点心意，居加壁纸。 50、居加，绘享受。 51、聚加墙画，千变万化。
英语儿歌45首歌 词 2018.6 1. Hello song 歌词(Lyrics) Hello, hello, hello how are you? I'm fine, I'm fine , I hope that you are too. Hello, hello, hello how are you? I'm fine, I'm fine , I hope that you are too 2. Finger Family 歌词Lyrics Daddy fin ger, Daddy fin ger, where are you? Here I am. Here I am. How do you do? Mammy fin ger, Mammy fin ger, where are you? Here I am. Here I am. How do you do? Brother fin ger, Brother fin ger, where are you? Here I am. Here I am. How do you do? Sister fin ger, Sister fin ger, where are you? Here I am. Here I am. How do you do? Baby fin ger, Baby fin ger, where are you? Here I am. Here I am. How do you do? 3. 《ABC so ng》歌词 A B C D , E F G H I J K , L M N O P Q R S , T U V W X Y Z Now I know my ABC, tell me what you think of me 4. Twi nkle Twi nkle Little Star 歌词 Twinkle, twinkle, little star,
Chants （1）“Hello,hello,how are you?” Hello, hello, how are you? Fine, fine,thank you. Hello, hello, how are you? Oh, oh,just so so. （2）“One—ten ” One,one,one,everybody run. Two,two,two,tie your shoe. Three,three,three,look at me. Four,four,four,fall on the floor. Five,five,five,jump up high. Six six six ,clap your hands. Seven seven seven,reach to the heaven. Eight eight eight,stamp your feet. Nine nine nine,turn around. Ten ten ten, please sit down. （3）“One—five” One one one a little dog run Two two two cats can see you Three three three birds in the tree Four four four rats on the floor Five five five what’s the time? （4）“One—ten” One is worm go go go Two is rabbit jump jump jump Three is cat miao miao miao Four is crab move move move Five is bird fly fly fly Six is ox walk walk walk Seven is rat run run run
墙纸壁纸的种类及特点 壁纸墙纸的种类 市场各种不同类型的壁纸，就其表面材质来讲，可将壁纸细分为以下几种。（一）纸质壁纸（英文名称：PAPER WALLCOVERINGS） 这类壁纸是在特殊耐热的纸上直接印花压纹而成。 特点：哑光、环保、天然、恬静、亲切感。 纸质壁纸在全世界的使用率占到17%左右。 （二）胶面壁纸（英文名称：VINYL WALLCOVERINGS） 表面为PVC材质的壁纸 1、纸底胶面壁纸（PAPER BACK VINYL WALLCOVERINGS） 目前使用最广泛的产品，在全世界的使用率占到70%左右 特点：防水，防潮，耐用，印花精致，压纹质感佳。 2、布底胶面壁纸（英文名称：FABRIC BACK VINYL WALLCOVERINGS） 分为十字布底和无纺布底（NON WOVEN） 特点：阻燃性质、布的坚韧性壁纸更佳，故耐用、耐磨、耐刮, 适合人流量大的公共贸易空间。 （三）壁布或称：纺织壁纸（英文名称：TEXTILE WALLCOVERINGS）表面为纺织品类之材料，也可以印花、压纹。 特点：视觉恬静、触感柔和、吸音、透气、亲和性佳、典雅、高贵。 此类壁纸在全世界的使用率为5%左右。 表面纺织品可以有以下种类： 1、纱线壁布：用不同式样的纱或线构成图案和色彩。 2、织布布类壁纸：有平织布面和缇花布面和无纺布面。
3、植绒壁布：将短织维植入底纸，产生质感极佳的绒布效果。 （四）金属类壁纸（英文名称：METALLIC WALLCOVERINGS） 用铝铂、金箔制成的特殊壁纸，以金色、银色为主要色系。 特点：防火、防水、华丽、高贵、价值感。 此类壁纸在全世界的据有率较少，为1%左右。 （五）自然材质类壁纸（英文名称：NATURAL MATERIAL WALLCOVERINGS） 用自然材质入草本、藤、竹、叶材编制而成。 特点：亲切天然、休闲、恬静的感觉，环保产品。 此类壁纸在全世界的据有率较少，为1%左右。 （1）植物编制类 （2）软木、树皮类壁纸 （3）石材、细砂类壁纸 （六）防火壁纸（英文名称：RETARDING VINYL WALLCOVERINGS） 用防火材质编制而成，常用玻璃纤维编制而成。 特点：防火性特佳，防火、防霉、常用于机场或公共建筑。此类壁纸又可分为表面防火、全面防火两种。 1、表面防火壁纸，是在塑胶涂层添加阻燃剂，底纸为普通不阻燃纸。 2、全面防火壁纸，在表面涂料层和底纸全部采用阻燃配方的壁纸。 此类壁纸在全世界的使用率较少，为1%左右。 （七）特特效果壁纸（英文名称：SPECIAL EFFECT WALLCOVERINGS） 此类壁纸在全世界的据有率较少，在一些特殊场所需要，为1%左右。 （1）荧光壁纸：在印墨中加有荧光剂在夜间会发光，常用于娱乐空间。 （2）夜光壁纸：使用吸光印墨，白天吸收光能，在夜间发光，常用于儿童房。
1. Hush-a-bye, baby, Daddy is near, Mammy's lady, And that's very clear. 不要吵，小宝宝， 爸爸陪你来睡觉； 妈妈不是男子汉， 这件事情你知道。 2. Hush-a-bye, baby, on the tree top, When the wind blows the cradle will rock; When the bough breaks the cradle will fail, Down will come baby, cradle and all. 小宝宝，睡树梢， 风儿吹，摇篮摇， 树枝断，摇篮掉， 里面宝宝吓一跳。 3. Bye, baby bunting, Daddy's gone a-hunting, Gone to get a rabbit skin
To wrap the baby bunting in. 睡吧睡吧胖娃娃， 爸爸打猎顶呱呱； 剥下一张兔子皮， 回家好裹胖娃娃。 4. He next met a barber, With powder and wig, He play'd him a tune, And he shaved an old pig. 理发师，他碰着， 戴着假发真时髦； 给他拉首开心典， 他给老猪剃猪毛。 5. Barney Bodkin broke his nose, Without feet we can't have toes; Crazy folks are always mad, Want of money makes us sad. 巴尼碰破大鼻子， 没脚不能长脚趾； 疯疯颠颠是疯子，
因很多家长向麦麦粥铺反映，想要儿歌50首大全的歌词。我们也花了大量的时间和精力，通过手打不断把歌词完善到趋于完整。希望可以让妈妈们和孩子一起在听的同时，更增加一份教学的乐趣。 您的五分好评是我们进步的最大动力，谢谢。 精心整理，真心希望对孩子的培养能有一丝帮助。 【儿歌串烧50首】第1首：《家庭称呼》歌词 爸爸爸爸daddy daddy daddy daddy 妈妈妈妈mami mami mami mami 哥哥弟弟brother brother brother 姐姐妹妹sister sister sister 爷爷爷爷grandpa grandpa grandpa 奶奶奶奶grandma grandma grandma 伯伯叔叔和舅舅 英文全都叫uncle uncle uncle uncle 姑姑婶婶和阿姨 英文全都叫auntie auntie auntie auntie 爸爸爸爸daddy daddy daddy daddy 妈妈妈妈mami mami mami mami 哥哥弟弟brother brother brother 姐姐妹妹sister sister sister 爷爷爷爷grandpa grandpa grandpa 奶奶奶奶grandma grandma grandma 伯伯叔叔和舅舅 英文全都叫uncle uncle uncle uncle 姑姑婶婶和阿姨 英文全都叫auntie auntie auntie auntie 爸爸爸爸daddy daddy daddy daddy 妈妈妈妈mami mami mami mami 哥哥弟弟brother brother brother 姐姐妹妹sister sister sister 爷爷爷爷grandpa grandpa grandpa 奶奶奶奶grandma grandma grandma 伯伯叔叔和舅舅 英文全都叫uncle uncle uncle uncle 姑姑婶婶和阿姨 英文全都叫auntie auntie auntie auntie 【儿歌串烧50首】第2首：《家族歌》歌词 爸爸的爸爸叫什么？爸爸的爸爸叫爷爷； 爸爸的妈妈叫什么？爸爸的妈妈叫奶奶； 爸爸的哥哥叫什么？爸爸的哥哥叫伯伯； 爸爸的弟弟叫什么？爸爸的弟弟叫叔叔； 爸爸的姐妹叫什么？爸爸的姐妹叫姑姑。 妈妈的爸爸叫什么？妈妈的爸爸叫外公； 妈妈的妈妈叫什么？妈妈的妈妈叫外婆；
假期特载】英语儿歌集（汇编） ? ?关靖华 ?399位粉丝 ? 1楼 致小读者和家长们： 1990年左右，武汉外语学院编撰的初级英语教学录像带是一套非常好的寓教于 乐的教材。并且曾在杭州市电视台播放。其中都是含有不同语法现象的“儿歌”。现在是假期，从今天开始，利用这个帖子逐个介绍这些儿歌。 练习1：字母 a 的“名称音”以及“祈使句”的训练： 儿歌的标题————Rain！雨！ —Rain! Rain! Go away! ———Come again another day! ————祈使句 —Little Johnny wants to play. “三单”现在 式 + s —Rain! Rain! Go away! ———Come again another day! —It's mother's washing day. 现在分词作形容词使用。 练习好 rain 的读音，则有利于发 train（火车）的读音。 ——声明：1. 请你们自己译成汉语；—————2. 家长可以用这些“儿歌”教你们的孩子。 ?2008-7-22 08:50 ?回复
? ?关靖华 ?399位粉丝 ? 2楼 练习 2 ：字母 e 的“名称音”以及“现在进行 时态”的训练： ——One! Two! Three! ————I love coffee. ————Billy loves tea. (三单现在时 态 + s ) ——Jimmy is swimming in the sea! 这是“现 在进行时态”的句子。 另外，通过以下歌曲可以练习现在进行时 态的疑问句： ————Are you sleeping? Are you sleeping ? ——————Brother John! Brother John! ————Morning bells are ringing! ——————Morning bells are ringing! ————Ding-ding-dong! Ding-ding-dong! 按《两只老虎！两只老虎！》那个调子唱。 ?2008-7-22 08:53 ?回复 ? ?关靖华 ?399位粉丝 ? 3楼 练习 3：字母 i 的“名称音”以及“习惯用 语 So do I!”的训练： 第一首短诗 — Apple-pie! Apple-pie! —— Peter likes apple-pie.“三单”现在时 + s ——So do I! So do I! 第二首短诗 ——I see Dinah Price, (Dinah Price 人名) ————Skating on the ice. ——I think skating is nice. ————So does Dinah Price！(第三身单数,现在时态 + es ) ?2008-7-22 08:56
壁纸介绍
墙纸 一、种类与作用 （一）墙纸的种类 1、按外观分，有印花墙纸、压花墙纸、发泡（浮雕）墙纸、印花压花墙 纸、压花发泡墙纸、印花发泡墙纸和印花发泡墙纸七种。可见墙纸表面的基本装 饰工艺印花、压花司发泡三种，它们的不同组合形成了上述七种不同的外观。 2、按功能分，有装饰性墙纸、防水墙纸、防火墙纸等种类。其中，装饰性墙 纸的使用最为广泛，防水墙纸与防火墙纸则使用在有特殊功能要求的地方。 3、按施工方法分，有现裱墙纸和背胶墙纸两大类。现裱墙纸即目前普遍使用 的在现场涂抹胶粘剂后才能裱糊的墙纸。背胶墙纸也称无基层墙纸，由PVC印花 薄膜、压敏胶、离型纸组成，使用时，不需要在现场涂抹胶粘剂，只需将离型纸 撕去即可将其粘贴于墙面。 4、按面层材料分 （1）纸基纸面墙纸：也称复合壁纸，将表纸和底纸经施胶压合合为一体后，现经印刷、压花、涂布等工艺生产而得。复合壁纸的透所性好，价格 便宜但；由于其基层和面层均为纸质，因而不耐水，易断裂，不便于 施工，裱糊后的易洁性差。 （2）织物面墙纸：其面层选用布、化纤、麻、绢、丝、绸、缎、呢或薄毡等织物，柔和、舒适，具有高雅感，有些绢、丝织物因其纤维的反光效 应而显得十分秀美，但此类墙纸的价格比较昂贵。 （3）天然材料面墙纸：以草、麻、木、叶等天然材料干燥后压粘于纸基上，具有浓郁的乡土气息，自然质朴。但耐久性、防火性较差，不宜用于 人流较大的场合。 （4）PVC墙纸：其面层主要采用聚氯乙烯树脂，故又称PVC墙纸。塑料墙纸有以下三种类型。 ①普通型----以80g/m2的纸为纸基，表面涂敷100g/m2PVC树脂而，其表 面装饰方法通常为印花、压花或印花与地压花的组合。 ②发泡型----100g/m2的纸为纸基，表面涂敷300—400g/m2的PVC树脂。 按民泡倍率的大小，又有低发泡和高发泡之氏别。其中，高发泡墙纸 表面星富有弹性的凹凸花纹，有一定吸声作用。低发泡墙通常在其其表 面印花。另有一种化学浮雕墙纸，即用有抑制发泡作用的油墨印花后再 发泡，形成具有不同色彩的凹凸花纹了图案。
1、Twinkle, twinkle, little star 一闪一闪小星星 Twinkle twinkle little star 一闪一闪小星星 How I wonder what you are? 我想知道你是什么？ Looking at your magic light 看着你闪着魔幻般的光芒 Watching over us tonight 在晚上注视着我们 Before my dreams take me away 在我的梦想带走我之前 I kneel beside my bed and pray 我在床旁边下跪并且为 For all the children in the dark 所有在黑暗中的孩子祈祷 Till tomorrow, twinkle little star.... 直到明天，闪光小星星…. Promise me you'll twinkle little star.... 请你许诺我，闪光小星星…. Cos everybody needs a little star. 因为大家需要一个小星星。 2、We Wish You A Merry Christmas 我们祝你圣诞快乐 We wish you a Merry Christmas.我们祝你圣诞快乐， We wish you a Merry Christmas.我们祝你圣诞快乐， We wish you a Merry Christmas and a Happy New Year.我们祝你圣诞快乐并新年快乐， Good tidings we bring to you and your kin.我们把佳音带给你及你的亲友， Good tidings for Christmas and a Happy New Year. 圣诞佳音并新年佳音。 3、Walking,walking 走啊走 Walking,walking,Walking,walking.走啊走啊走啊走， hop,hop,hop.跳，跳，跳， hop,hop,hop.跳，跳，跳， running,running,running.跑，跑，跑，
英文儿歌歌词大全 转载 1. Twinkle, Twinkle Little Star（—闪，一闪，小星星） Twi nkle. Twin kle Little Star, How I won der what you are! Up above the world so high, Like a diam ond in the sky. Twin kle, twi nkle little star, How I won der what you are! 2. ROW, ROW,ROW YOUR BOAT 划，戈U,划你的船 Row, Row, Row, Your Boat, Gently DownThe Stream. Merrily ,Merrily, Merrily, Merrily, life Is But A Dream. 3. ROUND THE VILLAGE 绕着村落 Go round and round the village, Go round and round the village, Go round and round the village, As we have done before. Go in and out the win dows. Go in and out the win dows. Go in and out the win dows. As we have done before. Now sta nd and play the part ner. Now sta nd and play the part ner. Now sta nd and play the part ner. And bow before you go. Now follow me to London. Now follow me to London. Now follow me to London. As we have done before. Nowshake his hand but leave him. Nowshake his hand but leave him. Now shake his hand but leave him. And bow before you go. 4. FLY, FLY, BUTTERFLY 飞，飞，蝴蝶 Fly, fly, fly , the butterfly. I n the meadow is flyi ng high. In
英文童谣47首（英汉对照）English Nursery Rhyme Collections 1．Hush-a-bye, baby, Daddy is near, Mammy's lady, And that's very clear. 不要吵，小宝宝， 爸爸陪你来睡觉； 妈妈不是男子汉， 这件事情你知道。 2．Hush-a-bye, baby, on the tree top, When the wind blows the cradle will rock; When the bough breaks the cradle will fail, Down will come baby, cradle and all. 小宝宝，睡树梢， 风儿吹，摇篮摇， 树枝断，摇篮掉， 里面宝宝吓一跳。 3．Bye, baby bunting, Daddy's gone a-hunting, Gone to get a rabbit skin To wrap the baby bunting in. 睡吧睡吧胖娃娃， 爸爸打猎顶呱呱； 剥下一张兔子皮， 回家好裹胖娃娃。 4．He next met a barber, With powder and wig, He play'd him a tune, And he shaved an old pig. 理发师，他碰着，戴着假发真时髦； 给他拉首开心典， 他给老猪剃猪毛。 5．Barney Bodkin broke his nose, Without feet we can't have toes; Crazy folks are always mad, Want of money makes us sad. 巴尼碰破大鼻子， 没脚不能长脚趾； 疯疯颠颠是疯子， 没钱只能哭鼻子。 6．A Little Betty Blue Lost her holiday shoe, What can little Betty do? Give her another to match the other, And then she may walk out in two. 小贝蒂， 丢只鞋， 这个难题怎么解？ 给只鞋， 配那只， 穿着鞋儿好上街。 7．Bbb, baaa, black sheep, Have you any wool? Yes, sir, yes, sir, Three bags full; One for the master, And one for the dame, And one for the little boy Who lives down the lane. 咩咩咩，黑绵羊， 多少羊毛身上长？ 先生先生你来看， 三个口袋鼓囊囊； 一袋主人面前放， 一袋是为主妇装， 一袋送给小男孩， 住在前面小街巷。 8．As a little fat man of Bombay Was smoking one very hot day, A bird called a snipe Flew away with his pipe, Which vexed the fat man of Bombay. 孟买有个胖老头， 大热天里把烟抽； 一只鹬鸟飞过头， 抢走他的大烟斗， 惹得老头把气怄。 9．When I was a little boy I had but little wit; 'tis a long time ago, And I have no more yet; Nor ever, ever shall Until that I die, For the longer I live The more fool am I. 当我是个小男孩， 那时我就没脑袋； 现在我的头发白， 还是没有长脑袋；