文献翻译模板_机械工程与力学学院_科院

有限元分析设计灯罩的级进模Abstract灯罩是汽车前大灯的重要组成部分，它主要是通过级进模制造。

在级进模成型中，多工位级进模是最强大的，因此在所有的级进模中是最困难的。

用有限元分析软件V5.2建模和分析圆顶形灯泡的成型过程。

模拟预测的数据和样品实验的数据十分吻合。

证明出的表面变形问题以及得出它的解决方案：对凸模圆角的应力分布的分析。

基于所提出的设计工具已经制造并在克利夫兰的生产厂成功运行。

自从成型的问题可以在工件成型之前被直观地发现以来，它与与传统的开发方法相比，模具调试时间从数周缩短到数天。

1.Introduction前照灯对于车辆在两个方面是至关重要的：（1）前照灯的美观是很重要的，因为它影响汽车的造型设计；（2）前照灯产生的光束质量影响车辆安全，如太强的光束分散对面司机的注意力，而微弱的光束会导致司机的视线不良。

由金属板制成的灯罩安装在灯泡前面以防止不必要的光（刺眼的光）从前照灯发射出去。

因此，灯罩的质量直接影响前照灯产生的光束的质量，见图1 [ 1,2 ]。

在前照灯透镜模块，灯罩是直观地考虑，因此表面质量特征是关键。

灯罩一般电镀铬镍，以避免表面瑕疵或不连续性。

最早的灯罩，参见图2A，是在20世纪80年代生产，由三个部件组成的。

不锈钢冲压件焊接在缝隙，连接到挡板上，并焊接到支架板。

在上世纪90年代，两个部件组成的灯罩被制造出来。

脚和杯焊接连在一起，外部表面电镀镍铬。

屏蔽罩的内表面涂耐高温黑色漆，防止前照灯的不必要的反射光。

从2000年以来，为了降低产品价格单件灯罩被开发，见图2C。

由于它的高效和准确性，级进模常常用于制造单件灯罩[ 3 ]。

由于单件的灯罩结合两件零件的特点，一个典型的单件灯罩需要13–25步成型工序来满足几何要求，如穿孔，穿刺，压花，多画，弯曲，修剪等等。

因此，灯泡罩级进模结构复杂，其开发是一个繁琐和耗时的过程[ 4 ]。

自上世纪70年代来计算机技术已被用来提高开发级进模的设计效率。

Quantifying the Trade Effects of Technical Barriers to Trade: Evidence from China 1. IntroductionTechnical barriers to trade（TBT）are now widespread and have increasing impacts on international trade. The spread of TBT may have some special reasons.First, it’s legitimate. The WTO members are authorized by WTO TBT/SPS Agreement to take such measures in order to protect human health, as well as animal and plant health, provided that the enforced measures are not disguised protectionism. Second, as Baldwin (1970) emphasized, ―The lowering of tariffs has, in effect, been like draining a swamp. The lower water level has revealed all the snags and stumps of non-tariff barriers that still have to be cleared away‖. Wallner (1998) considered this phenomenon as a ―law of constant protection‖, referring to perfect substitutability between tariff and none-tariff barriers in maintaining a degree of desired domestic protection.Third, with the trade liberalization process, the remaining barriers, like TBT have a more important but not a less important impact due to the ―globalization magnification effect‖, seemingly minor differences in technical norms can have an outsized effect on production and trade (Baldwin 2000). Fourth, the increasing income of importing country and consumer preference may result in a higher demand for product quality, safety and environment protection.Since the proliferation of TBT and its increasing trade-restrictive impacts, OECD (2001) drew attention to TBT and suggested more empirical research on it, becausethe quantitative analysis is an important step in the regulatory reform process and can help inform governments to define more efficient regulations. However, due to the theoretical complexity and data s carcity, TBT have been considered as ―one of the most difficult NTBs imaginable to quantify‖ （Deardorff and Stern 1997）So far, there is not a preferred quantification strategy and claims abound on both sides about―whether such restrictions tend to reduce trade by virtue of raising compliance costsor expand trade by increasing consumer confidence in the safety and quality of imported goods‖ (Maskus and Wilson 2001).Maskus and Wilson (2001), Maskus, Otsuki, and Wilson (2001), Beghin and Bureau (2001), Ferrantino (2006) and Korinek, Melatos and Rau (2008) etc provide comprehensive overviews of key economic issues relating to TBT modeling and measurement. Based on these literatures, quantification techniques can be broadly grouped into two categories. Ex-post approaches such as gravity-based econometric models tend to estimate the observed trade impact of standards. On the other hand, ex ante methods such as simulations involving the calculation of tariff equivalents are usually employed to predict the unobserved welfare impact. No approach is or can bedefinitive. Each methodology offers its own pluses and minuses, depending on a number of factors, including the nature of the technical measure, the availability of data, and the goal of measurement. (Popper et al 2004)Concerning the trade effect1, different from any other trade measures, TBT have both trade promotion and trade restriction effects. Although a unified methodology does not exist, the gravity model is most often used for the evaluation. The gravity model employs a number of different approaches to measure the TBT. The policy indices obtained by survey can be used as proxy for the severity of TBT, and direct measures based on inventory approach are incorporated too. Beghin and Bureau（2001）summarized three sources of information that can be used to assess the importance of domestic regulations as trade barriers: (i) data on regulations, such as the number of regulations, which can be used to construct various statistical indicators,or proxy variables, such as the number of pages of national regulations; (ii) data on frequency of detentions, including the number of restrictions; frequency ratios and the import coverage ratio (iii) data on complaints from the industry against discriminatory regulatory practices and notifications to international bodies about such practices. Besides the above mentioned approach, some studies try to use explicit standards requirements such as maximum residue levels too.There are a considerable number of study combined the variable for the stringency of TBT with gravity model to estimate the direction of the trade impact.Swann, Temple, and Shurmer (1996) used counts of voluntary national and international standards recognized by the UK and Germany as indicators of standard over the period1985–1991, their findings suggest that share standards positively impact exports, but had a little impact on imports; unilateral standards positively influence imports but negatively influence exports. Moenius (2004, 2006) examines the trade effect of country specific standards and bilaterally shared standards over the period 1985-1995. Both papers used the counts of binding standards in a given industry as a measure of stringency of standards.Moenius (2004) focus on 12 OECD countries and found that at aggregate level, bilaterally shared standards and country-specific standards implemented by the importing or exporting country are both trade-promoting on average. At the industry level, the only variation is that importer-specific standards have the expected negative trade effect in nonmanufacturing sectors such as agriculture. In manufacturing industries, importer-specific standards are trade promoting too. Moenius (2006) confirm the result of Moenius (2004) in that bilateral standard in EU has very strong trade promoting effect as to the trade between EU and non-EU members, but harmonization decrease the internal trade of EU. Moenius (2006) distinguish 8 EU members and 6 non-EU developed countries. So he also found that importer specific standard in EU promote trade between EU members, but depress trade between EU members and non-EU members; Exporter specific standard inside EU has little trade promoting effect ,but export specific standard of non-EU members expand their tradewith EU.The paper using frequency or coverage ratio within a gravity model framework include Fontagné, Mimouni and Pasteels (2005) and Disdier, Fontagné, and Mimouni (2007). Both of them use the frequency ratio based on notification directly extracted from the TRAINS database. Fontagné, Mimouni and Pasteels (2005) collect data on 61 product groups, including agri-food products in 2001. Their paper generalized the findings of Moenius (2004): NTMs, including standards, have a negative impact on agri-food trade but an insignificant or even positive impact on the majority of manufactured products. Moreover, they distinguish trade effects among ―suspicious products‖, ―sensitive products‖ as well as ―remaining products‖ according to the number of notifications and distinguish different country group. Based on data covering 61 exporting countries and 114 importing countries, they find that over the entire product range, LDCs, DCs and OECD countries seem to be equally affected. However, OECD agrifood exporters tend to benefit from NTMs, at the expense of exporters from DCs and LDCs. The authors account for tariff and other NTM in the model , so they also find that tariffs matter more than NTMs, particularly foragri-food products on which comparatively high tariffs are levied.Disdier, Fontagné, and Mimouni (2008) estimate the trade effect of standards and other NTMs on 690 agri-food products (HS 6-digit level). Their data covers bilateral trade between importing OECD countries and 114 exporting countries (OECD and others) in 2004. As well as a frequency index, they use a dummy variable that records whether the importing country has notified at least one NTM and ad-valorem tariff equivalent measures of NTMs as two alternative approaches to measure NTMs. They find that these measures have on the whole a negative impact on OECD imports and affect trade more than other trade policy measures such as tariffs. The tariff equivalent shows the smallest effect. When they consider different groups of exporting countries, they show that OECD exporters are not significantly affected by SPS and TBTs in their exports to other OECD countries while developing and least developed countries’ exports are negatively and significantly affected. For the subsample of EU imports, NTMs no longer influence OECD exports positively, but exports from LDCs and DCs seem to be more negatively influenced by tariffs and SPS & TBTs than that of OECD. Finally, their sectoral analysis suggests an equal distribution of negative and positive impacts of NTBs on agricultural trade.Many studies are supportive of using maximum residue levels to directly measure the severity of food safety standards within a gravity model. These studies include Otsuki, Wilson and Sewadeh (2001a, b), Wilson and Otsuki (2004b,c) Wilson,Otsuki and Majumdsar (2003), Lacovone (2003) and Metha and Nambiar（2005）. These studies tend to focus on specific cases of standards for particular products and countries. Otsuki, Wilson and Sewadeh (2001a,b) and Wilson and Otsuki (2004b) examine the trade effect of aflatoxin standards in groundnuts and other agriculturalproducts (vegetables,fruits and cereals). The first two papers covered African export data to EU members and the third paper covered 31 exporting countries (21 developing countries) and 15 importing countries(4 developing countries). All three studies show that imports are greater when the importing country imposes less stringent aflatoxin standards on foreign products. Lacovone (2003) also used MRL of aflatoxin and found that there were substantial export losses to Latin-America from the tightening of the aflatoxin standards set by Europe. Similarly, Wilson, Otsuki and Majumdsar (2003) analyze the effect of standards for tetracycline residues on beef trade and find that regardless of the exporter standards, the standards of tetracycline imposed by the importing countries have the same negative trade impact. Wilson and Otsuki (2004c) analyze MRL relating to chlorpyrifos and Metha and Nambiar（2005）analyze the impact of MRL on India’s export of four processing agri-products to 7 developed countries and yield the similar result.Since our paper focus on the trade effect of technical barrier, we will use the most suitable ex post quantification methods. Moreover, while frequency and coverage ratio can give some guidance as to the potential trade impact of a technical measure, econometric model is used to estimate its magnitude.Our paper make contributions to the current literature in the following ways: First, in contrast to the existing empirical studies which exclusively focus on developed countries TBT, this paper focuses on a developing country, China. Second, this paper has a self-constructed trade measure database based on disaggregated data covered all HS2 products, including agricultural and processing food products (HS01-24) and manufacturing products (HS25-97) so that it can identify the sectors/products with predominant negative impacts on trade. Third, tariff data, import licenses and quotas are included as additional explanatory variables, allowing the distinction between the impact of traditional trade barriers and TBT on trade. Fourth, our data covers 43 exporting countries (including 25 developing countries), it helps to distinguish the trade effect of different country groups. Fifth, in contrast to most literature relied on cross-section data1, our paper covers 9 years time series data on TBT, so we can both capture variation across products and variation within products over time, in particular the changing effects before and after China’s entry into the WTO.The rest of the paper is organized as follows. In section 2, we construct a TBT database from 1998 to 2006 and use inventory approach (frequency index and coverage ratio) to quantify the stringency of technical measures in China. In section 3, we present our regression model, discuss all the variables and describe the data. In section 4, we discuss our findings. We make some concluding remarks in section 5. 2. Quantification of TBT2.1 Measurement of NTM: Inventory approachThe inventory approach allows estimates of the extent of trade covered by NTMs or their frequency of application in specific sectors or against individual countries orgroups of countries. Bora etc (2002) reviews various approaches to quantify NTMs and give a detailed instruction on how to construct frequency index and coverage ratio as follows. The percentage of trade subject to NTMs for an exporting country j at a desired level of product aggregation is given by the trade coverage ratio:2.2 China’s NTM database: data description and methodologyFollowed the method described above, we will construct a Chinese NTMs database from 1998 to 2006 by using inventory approach. The data covered 96 HS2 digit level agricultural and manufacturing industries. First, we calculate a series of frequency index at 4-digit-level of the Harmonized System and then aggregate them into import coverage ratio at HS2. In this database, data are collected by tariff item on the application of a range of tariff and NTMs (TBT, license and import quota) against Chinese imports. The main source of the information on the trade control measures in the database is from Chinese government publications. ―Administrative Measures Regarding Impor t & Export Trade of the People's Republic of China‖ published bythe Ministry of Commerce and Custom General Administration of China provide detailed information at HS 8-digit-level on tariff and non-tariff measures.The code list of supporting documents subject to customs control provide detailed name of licenses or instruments of ratification, which helps to identify whether a tariff line product subject to a specific non-tariff barrier. Concerning the technical measures, it includes those government administrative measures for environmental protection, safety, national security and consumer interests. The code subject to TBT control remains almost the same during the 1998-2001. Specificly, the code subject to TBT in 1998 is IRFM, denoting for Import commodity inspection (I), Quarantine control release for animal, plant and thereof product (R), Import food inspection certificate (F) and Medicine inspection certificate (M). The code concerning TBT in 1999-2001 is AMPR, denoting for Import inspection and quarantine (A), Import commodity inspection (M), Import animal, plant and thereof product inspection (P) and Import food hygiene supervision inspection (R). Since 2002, the government revised the code list into details. Although there is some tiny difference between years, the new code list remains quite stable during 2002-2006 (See the code list in Annex1). The code subject to TBT is ACFIPQSWX during 2002-2005 and AFIPQSWX in 2006, each code stands for Certificate of inspection for goods inward (A), Certificate of inspection for goods inward: Civil commodity import inspection (C), Import licencing certificate for endangered species (F), Import or export permit for psychotropic drugs (I), Import permit for waste and scraps (P), Report of inspection of soundness on import medicines (Q), Import or export registration certificate for pesticides (S), Import or export permit for narcolic drugs (W), Environment control release noticefor poisonous chemicals (X).Note that our data on trade control measures do not have a bilateral dimension. TBT measures, import license and import quotas are enforced unilaterally by Chinese government and applicable to all exporting countries. When we calculate coverageratio and frequency ratio, Vi is the total value of imports in product i from the whole world and Mi indicates whether there are imports from the whole world of good i. Hence, in a specific year, NTM variables vary among different sectors but remain the same among different countries. Although we miss the bilateral dimension associated with such measures, still the exporters are differently affected by TBT measures depending on the structure of their exports in terms of products and markets.To be precise, the frequency ratio of TBT (FR-TBT) measures the proportion of product items covered by TBT measures within a product category, which varies between 0% (no coverage) and 100% (all products covered). We first count the number of HS items (defined at the 8 digit level of the HS) covered by the TBT measures and divide it by the maximum number of product items belonging to the product category (defined here at the 4-digit level of the HS). So we get the results of frequency ratio of TBT at HS4 digit level. For example, regarding HS2402 (Cigars, cheroots, cigarillos and cigarettes, of tobacco or of tobacco substitutes), there are 3 product items with codes 24021000 (Cigars, cheroots and cigarillos, containing tobacco), 24022000 (Cigarettes containing tobacco), 24029000(other). Only one of them (HS24022000) is covered by TBT measures, so the corresponding TBT frequency index equals 33.33% (1 / 3). Then we do the same at HS2 digit level.The import coverage ratio(IC-TBT) measures the proportion of affected import of the total import within a product category. Take HS17 (Sugars and sugar confectionery) as an example, there are 4 product items with code HS1701, 1702, 1703 and 1704 respectively. Only three of them (except HS1703) are covered by TBT measures (it means the frequency index for HS1703 equals 0, while the other three are between 0 and 100%), the import value of the TBT affected products sum up to 111.216 million US$, the import valued of HS17 is 182.244 million US$, so the corresponding TBT import coverage ratio equals 66.46% (111.216/182.244).2.3 TBT rocked sectors in ChinaBy calculating frequency index and import coverage ratio of TBT, we can examine which products are the most affected. According to the definition by UNCTAD (1997), those with a frequency ratio and coverage ratio both above 50% are TBT rocked product. In our sample, 34 products（HS01-24; HS30,31,33; HS 41;HS 44-47; HS51 and HS72）are TBT-rocked during the period from 1998-2002. In 2003, two product items (HS 42-43) become TBT-rocked. In 2004, two more products (HS 50 and HS80) added into the category. During 2005-2006, HS78 are included asTBT-rocked products but HS50 is excluded. See Annex2 for the detailed product information of TBT rocked products.There are a significant number of products, particularly agricultural products and processing food widely affected by technical measures (HS01-24). However, enforcement of TBT is not limited to those products, but is spreading to manufacturing products also. The TBT rocked manufacturing products includePharmaceutical products（HS30, Essential oils, perfumes, cosmetics, toiletries (HS33), Raw hides and skins, leather, furskins and articles thereof (HS41-43), Wood and articles of wood（HS44-46）, Base metals and articles thereof, like iron and steel, aluminium and tin.( HS72, 76 and 80) etc. They are either labor intensive products or final goods concerning consumer safety, like medicaments in particular. Although TBT rocked sectors cover about 1/3 of total number of products at HS2 digit level, the proportion of affected trade is limited: about 10-16% of total import. However technical barriers are the most frequent type of NTM, the import subject to TBT account for above 90% of Chinese total import except for the rare case in 2001 (77.29%). (see Table 1).3. Model, methodology and data3.1 Model specificationWe use gravity model to examine how TBT imposed by China influence the country’s bilateral trade. To capture the size effect, population of both countries is used as proxy for exporting country’s supply capacities and importing country’s demand capacity. Per capita income of the two countries is included because higher income countries trade more in general. Transport costs are measured using the bilateral distance countries’ cultural proximity. We therefore control for this p roximity by introducing a common language dummy variable. Based on the typical gravity model, we introduce our key variables—tariff and non-tariff trade barriers. Our basic regression model takes the following forms:4. Empirical results4.1 The whole sample resultsTable 2-1 shows the summary statistics of our key variables. Table 2-2 reports the Pearson coefficients of the trade control measure variables. For the frequency index, import license and tariff appear to be negatively correlated. For the coverage ratio, besides import license, TBT seems to be slightly negative correlated with the tariff. Except for the above rare cases, the import control policies are positively correlated to each other. In general, different kinds of import control measures in China seem to be complementary to each other. Among them, import license and import quota have the highest positive coefficient, this accords with the fact that these two measures are sometimes combined together. Normally a country will distribute quota by issuing import license.We use OLS to estimate the gravity model. Regressions are run on pooled data for 9 years (see Table 3 and 4) and on data for each year separately (see Table 5 and 6). Table 3 and 5 report the result using frequency index, while Table 4 and 6 report the result using coverage ratio, both at HS 2-digit-level. For the whole sample regression results in Table 3 and 4, column 1 shows the result of the basic gravity model, column 2 introduces tariff and non-tariff barriers, column 3 tries to identify the difference between developing and developed countries and column 4 adds WTO as an additional control variable. Year-country-product fixed effect is used for all thespecifications.The results for standard gravity explanatory variables are consistent with prior expectations except for Contig as a rare case. The effect of GDPPC, POP and dist is positive and highly significant for all regressions. It implies that a 1 percent increase in the population of exporting country yields a 1.39-1.47 percent increase in the bilateral trade, and a 1 percent increase in the per capita GDP of exporting country yields a 0.91-1.40 percent increase in the bilateral trade. A 1 percent increase in geographic distance between the two trade partners will result a 1.42-1.45 percent decrease in bilateral trade. The effect of POPchina and GDPPCchina is positive and significant in two regressions. If Chinese population or per capita GDP increase 1 percent, Chinese import will increase 10.8-14.1 percent or 2.0-2.8 percent respectively. The coefficient for Comlang is positively significant in all specifications, which implies that if the exporting country share a same language with China, Chinese import will be stimulated by 2.6-3.3 percent. If the exporting market belongs to China, it will increase Chinese import by 0.3 percent. The coefficient for Contig is significantly negative, which implies that if the exporting country and China are contiguous, Chinese import will decrease 0.76-0.99 percent. This result is not consistent to the prior expectation. But the intuition is easily understood because the most important importing markets such as the US, Japan, EU members are not contiguous with China mainland.We then discuss the key explanatory variable, Tariff have a significant negative effect on Chinese import. A 1 percent increase in the MFN tariff will decrease import value by 0.64-0.66 percent. The results of the frequency index of NTM are all significant. A 1 unit increase in FRTBT will decrease import value by 1.1%, a 1 unit increase in FRQ will decrease import value by 1.7%, a 1 unit increase in FRL will increase import value by 4.1%. The results of the coverage ration of NTM are different in some extent with that of frequency index. A 1 unit increase in ICTBT will increase import value by 0.2%, a 1 unit increase in ICL will increase the import value by 2.7%, and the coefficient for ICQ is negative but not statistically significant.Table 5 and 6 give us a clear picture about how the effect of trade control measures change yearly. Tariff remains negatively significant for all 9 years.Moreover, the elasticity for Tariff dramatically increased since 2003. The trade depressing effect of Tariff nearly doubled after China’s entry into the WTO. FRTBT is negatively significant in all year specifications, and the coefficient remains stable through the sample period. FRL is positively significant while FRQ is negatively significant except for three years. In 1998, 1999 and 2001, FRL is insignificant while FRQ is positively significant due to the multicollinearity1. The result of ICTBT is changeable during the sample period. The coefficient of ICTBT is positively significant during 1998-2002, negatively significant in 2003 and insignificant during the remaining years. ICL remains positively significant during all 9 years, plus the elasticity for ICL slightly increased since 2002. ICQ is significant during 1998-2002,but the sign of the coefficient is changeable, and ICQ becomes insignificant since 2003. So ICQ doesn’t affect bi lateral trade value in a systematic way. From the yearly result, we observe that some of the trade control measure change trade patterns in a different way. Does the trade effect change significantly before and after China entry into the WTO? Whether there is any systematic difference in the trade effect between developing and developed countries? To solve these two problems, we add two interactions. Column 5 introduces the interaction between Developing and each of frequency indices of trade measures. Column 6 adds the interaction between WTO and each of coverage ratios of trade measure. As we can see, tariff (Tariff) and import quota (FRQ and ICQ) seem to have no difference between difference country groups. The change of FRTBT will affect Chinese import from developing countries less than that from developed countries. The change of ICTBT will affect Chinese import from developing countries more than that from developed countries. The change in FRL or ICL will have less impact on Chinese import from developing countries than from developed countries. On average, tariff, license have an increasing effect but quota has a decreasing effect after China’s entry into the WTO. The effect of TBT does not change significantly.5. ConclusionThe results of current literature suggest that TBT in importing country has restrictive trade effect and exports of poor countries are affected more. The paper explores whether technical measures imposed by China have restrictive effects for the imports from main exporters all over the world. Our research confirms some of the results reported elsewhere in the literature while differences remain in some aspects.First, in general trade control measures do have import restrictive effect in China. Second, tariff plays an important r ole even after China entry into the WTO. So far it’s still the most efficient policy tool. Third, TBT is the most frequently used NTM in China and cover almost all the imports. TBT do have some trade depressing effect but the effect is relatively small compared to the effect of tariff. Fourth, in contrast to the general belief that TBT works as a substitute to tariff and traditional NTM in developed countries（Thonsbury1998, Abbott 1997 etc）, there is no obvious substitution effect between tariff and TBT in China, moreover, the TBT is complementary to tariff in some extent.定量商业作用技术贸易壁垒：证据从中国1. 介绍技术贸易壁垒TBT现在普遍并且增加了对国际贸易的冲击。

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机械类外文文献及翻译(文档含中英文对照即英文原文和中文翻译)原文：GEAR AND SHAFT INTRODUCTIONAbstract:The important position of the wheel gear and shaft can't falter in traditional machine and modern machines.The wheel gear and shafts mainly install the direction that delivers the dint at the principal axis box. The passing to process to make them can is divided into many model numbers, using for many situations respectively. So we must be the multilayers to the understanding of the wheel gear and shaft in many ways .Key words: Wheel gear; ShaftIn the force analysis of spur gears, the forces are assumed to act in a single plane. We shall study gears in which the forces have three dimensions. The reason for this, in the case of helical gears, is that the teeth are not parallel to the axis of rotation. And in the case ofbevel gears, the rotational axes are not parallel to each other. There are also other reasons, as we shall learn.Helical gears are used to transmit motion between parallel shafts. The helix angle is the same on each gear, but one gear must have a right-hand helix and the other a left-hand helix. The shape of the tooth is an involute helicoid. If a piece of paper cut in the shape of a parallelogram is wrapped around a cylinder, the angular edge of the paper becomes a helix. If we unwind this paper, each point on the angular edge generates an involute curve. The surface obtained when every point on the edge generates an involute is called an involute helicoid.The initial contact of spur-gear teeth is a line extending all the way across the face of the tooth. The initial contact of helical gear teeth is a point, which changes into a line as the teeth come into more engagement. In spur gears the line of contact is parallel to the axis of the rotation; in helical gears, the line is diagonal across the face of the tooth. It is this gradual of the teeth and the smooth transfer of load from one tooth to another, which give helical gears the ability to transmit heavy loads at high speeds. Helical gears subject the shaft bearings to both radial and thrust loads. When the thrust loads become high or are objectionable for other reasons, it may be desirable to use double helical gears. A double helical gear (herringbone) is equivalent to two helical gears of opposite hand, mounted side by side on the same shaft. They develop opposite thrust reactions and thus cancel out the thrust load. When two or more single helical gears are mounted on the same shaft, the hand of the gears should be selected so as to produce the minimum thrust load.Crossed-helical, or spiral, gears are those in which the shaft centerlines are neither parallel nor intersecting. The teeth of crossed-helical fears have point contact with each other, which changes to line contact as the gears wear in. For this reason they will carry out very small loads and are mainly for instrumental applications, and are definitely not recommended for use in the transmission of power. There is on difference between a crossed heli : cal gear and a helical gear until they are mounted in mesh with each other. They are manufactured in the same way. A pair of meshed crossed helical gears usually have the same hand; that is ,a right-hand driver goes with a right-hand driven. In the design of crossed-helical gears, the minimum sliding velocity is obtained when the helix angle areequal. However, when the helix angle are not equal, the gear with the larger helix angle should be used as the driver if both gears have the same hand.Worm gears are similar to crossed helical gears. The pinion or worm has a small number of teeth, usually one to four, and since they completely wrap around the pitch cylinder they are called threads. Its mating gear is called a worm gear, which is not a true helical gear. A worm and worm gear are used to provide a high angular-velocity reduction between nonintersecting shafts which are usually at right angle. The worm gear is not a helical gear because its face is made concave to fit the curvature of the worm in order to provide line contact instead of point contact. However, a disadvantage of worm gearing is the high sliding velocities across the teeth, the same as with crossed helical gears.Worm gearing are either single or double enveloping. A single-enveloping gearing is onein which the gear wraps around or partially encloses the worm.. A gearing in which each element partially encloses the other is, of course, a double-enveloping worm gearing. The important difference between the two is that area contact exists between the teeth of double-enveloping gears while only line contact between those of single-enveloping gears. The worm and worm gear of a set have the same hand of helix as for crossed helical gears, but the helix angles are usually quite different. The helix angle on the worm is generally quite large, and that on the gear very small. Because of this, it is usual to specify the lead angle on the worm, which is the complement of the worm helix angle, and the helix angle on the gear; the two angles are equal for a 0-deg. Shaft angle.When gears are to be used to transmit motion between intersecting shaft, some of bevel gear is required. Although bevel gear are usually made for a shaft angle of 0 deg. They may be produced for almost any shaft angle. The teeth may be cast, milled, or generated. Only the generated teeth may be classed as accurate. In a typical bevel gear mounting, one of the gear is often mounted outboard of the bearing. This means that shaft deflection can be more pronounced and have a greater effect on the contact of teeth. Another difficulty, which occurs in predicting the stress in bevel-gear teeth, is the fact the teeth are tapered.Straight bevel gears are easy to design and simple to manufacture and give very good results in service if they are mounted accurately and positively. As in the case of squr gears, however, they become noisy at higher values of the pitch-line velocity. In these cases it is often go : od design practice to go to the spiral bevel gear, which is the bevel counterpart of thehelical gear. As in the case of helical gears, spiral bevel gears give a much smoother tooth action than straight bevel gears, and hence are useful where high speed are encountered.It is frequently desirable, as in the case of automotive differential applications, to have gearing similar to bevel gears but with the shaft offset. Such gears are called hypoid gears because their pitch surfaces are hyperboloids of revolution. The tooth action between such gears is a combination of rolling and sliding along a straight line and has much in common with that of worm gears.A shaft is a rotating or stationary member, usually of circular cross section, having mounted upon it such elementsas gears, pulleys, flywheels, cranks, sprockets, and other power-transmission elements. Shaft may be subjected to bending, tension, compression, or torsional loads, acting singly or in combination with one another. When they are combined, one may expect to find both static and fatigue strength to be important design considerations, since a single shaft may be subjected to static stresses, completely reversed, and repeated stresses, all acting at the same time.The word “shaft” covers numerous v ariations, such as axles and spindles. Anaxle is a shaft, wither stationary or rotating, nor subjected to torsion load. A shirt rotating shaft is often called a spindle.When either the lateral or the torsional deflection of a shaft must be held to close limits, the shaft must be sized on the basis of deflection before analyzing the stresses. The reason for this is that, if the shaft is made stiff enough so that the deflection is not too large, it is probable that the resulting stresses will be safe. But by no means should the designer assume that they are safe; it is almost always necessary to calculate them so that he knows they are within acceptable limits. Whenever possible, the power-transmission elements, such as gears or pullets, should be located close to the supporting bearings, This reduces the bending moment, and hence the deflection and bending stress.Although the von Mises-Hencky-Goodman method is difficult to use in design of shaft, it probably comes closest to predicting actual failure. Thus it is a good way of checking a shaft that has already been designed or of discovering why a particular shaft has failed in service. Furthermore, there are a considerable number of shaft-design problems in which the dimension are pretty well limited by other considerations, such as rigidity, and it is only necessary for the designer to discover something about the fillet sizes, heat-treatment,and surface finish and whether or not shot peening is necessary in order to achieve the required life and reliability.Because of the similarity of their functions, clutches and brakes are treated together. In a simplified dynamic representation of a friction clutch, or brake, two in : ertias I and I traveling at the respective angular velocities W and W, one of which may be zero in the case of brake, are to be brought to the same speed by engaging the clutch or brake. Slippage occurs because the two elements are running at different speeds and energy is dissipated during actuation, resulting in a temperature rise. In analyzing the performance of these devices we shall be interested in the actuating force, the torque transmitted, the energy loss and the temperature rise. The torque transmitted is related to the actuating force, the coefficient of friction, and the geometry of the clutch or brake. This is problem in static, which will have to be studied separately for eath geometric configuration. However, temperature rise is related to energy loss and can be studied without regard to the type of brake or clutch because the geometry of interest is the heat-dissipating surfaces. The various types of clutches and brakes may be classified as fllows:. Rim type with internally expanding shoes. Rim type with externally contracting shoes. Band type. Disk or axial type. Cone type. Miscellaneous typeThe analysis of all type of friction clutches and brakes use the same general procedure. The following step are necessary:. Assume or determine the distribution of pressure on the frictional surfaces.. Find a relation between the maximum pressure and the pressure at any point. Apply the condition of statical equilibrium to find (a) the actuating force, (b) the torque, and (c) the support reactions.Miscellaneous clutches include several types, such as the positive-contact clutches, overload-release clutches, overrunning clutches, magnetic fluid clutches, and others.A positive-contact clutch consists of a shift lever and two jaws. The greatest differences between the various types of positive clutches are concerned with the design of the jaws. To provide a longer period of time for shift action during engagement, the jaws may be ratchet-shaped, or gear-tooth-shaped. Sometimes a great many teeth or jaws are used, and they may be cut either circumferentially, so that they engage by cylindrical mating, or on the faces of the mating elements.Although positive clutches are not used to the extent of the frictional-contact type, they do have important applications where synchronous operation is required.Devices such as linear drives or motor-operated screw drivers must run to definite limit and then come to a stop. An overload-release type of clutch is required for these applications. These clutches are usually spring-loaded so as to release at a predetermined toque. The clicking sound which is heard when the overload point is reached is considered to be a desirable signal.An overrunning clutch or coupling permits the driven member of a machine to “freewheel” or “overrun” bec ause the driver is stopped or because another source of power increase the speed of the driven. This : type of clutch usually uses rollers or balls mounted between an outer sleeve and an inner member having flats machined around the periphery. Driving action is obtained by wedging the rollers between the sleeve and the flats. The clutch is therefore equivalent to a pawl and ratchet with an infinite number of teeth.Magnetic fluid clutch or brake is a relatively new development which has two parallel magnetic plates. Between these plates is a lubricated magnetic powder mixture. An electromagnetic coil is inserted somewhere in the magnetic circuit. By varying the excitation to this coil, the shearing strength of the magnetic fluid mixture may be accurately controlled. Thus any condition from a full slip to a frozen lockup may be obtained.齿轮和轴的介绍摘要:在传统机械和现代机械中齿轮和轴的重要地位是不可动摇的。

机械工程专业外文文献及翻译文献一（外文标题）
摘要：
该文献研究了机械工程领域中的某个具体问题。

通过实验方法和数学模型的分析，作者得出了一些有意义的结论。

本文介绍了作者的研究方法和结果，并讨论了其在机械工程领域的应用前景。

翻译：
（将文献的主要内容用简洁准确的语言翻译成中文）
文献二（外文标题）
摘要：
该文献探讨了机械工程领域中的另一个重要问题。

通过实证分析和理论推导，作者提出了解决方案，并对其进行了验证。

本文阐述了作者的方法和实验结果，并探讨了其在实践中的应用潜力。

翻译：
（将文献的主要内容用简洁准确的语言翻译成中文）
文献三（外文标题）
摘要：
该文献研究了机械工程领域中的另一个新颖课题。

作者通过数
值模拟和实验验证，得出了一些有趣的发现。

本文介绍了作者的研
究过程和结果，并讨论了其对机械工程领域的影响。

翻译：
（将文献的主要内容用简洁准确的语言翻译成中文）
总结
本文档介绍了三篇机械工程专业的外文文献，包括摘要和翻译。

这些文献都对机械工程领域中的不同问题进行了研究，并提出了相
关的解决方案和发现。

希望这些文献能为机械工程专业的学生和研
究人员提供有价值的参考和启发。

The Sunflower Seed Huller and Oil PressBy Jeff Cox-- from Organic Gardening, April 1979, Rodale PressIN 2,500 SQUARE FEET, a family of four can grow each year enough sunflower seed to produce three gallons of homemade vegetable oil suitable for salads or cooking and 20 pounds of nutritious, dehulled seed -- with enough broken seeds left over to feed a winter's worth of birds.The problem, heretofore, with sunflower seeds was the difficulty of dehulling them at home, and the lack of a device for expressing oil from the seeds. About six months ago, we decided to change all that. The job was to find out who makes a sunflower seed dehuller or to devise one if none were manufactured. And to either locate a home-scale oilseed press or devise one. No mean task.Our researches took us from North Dakota -- hub of commercial sunflower activity in the nation -- to a search of the files in the U.S. Patent Office, with stops in between. We turned up a lot of big machinery, discovered how difficult it is to buy really pure, unrefined vegetable oils, but found no small-scale equipment to dehull sunflowers or press out their oil. The key to success, however, was on our desk the whole time. In spring 1977, August Kormier had submitted a free-lance article describing how he used a Corona grain mill to dehull his sunflower seeds, and his vacuum cleaner exhaust hose to blow the hulls off the kernels. A second separation floated off the remaining hulls, leaving a clean product. We'd tried it, but because some kernels were cracked and the process involved drying, we hadn't been satisfied. Now we felt the best approach was to begin again with what we learned from Mr. Kormier and refine it.Staff Editor Diana Branch and Home Workplace Editor Jim Eldon worked with a number of hand- and electric-powered grain mills. While the Corona did a passable job, they got the best results with the C.S. Bell #60 hand mill and the Marathon Uni Mill, which is motor-driven. "I couldn't believe my eyes the first time I tried the Marathon," Diana says. "I opened the stones to 1/8th inch, and out came a bin full of whole kernels and hulls split right at the seams. What a thrill that was!"She found that by starting at the widest setting,and gradually narrowing the opening, almost every seed was dehulled. The stones crack the hulls open, then rub them to encourage the seed away from the fibrous lining. The Bell hand mill worked almost as well. "As long as the stones open at least as wide as the widest unhulled seed, any mill will work," she says.Because the seed slips through the mill on its flat side, grading is an important step to take before dehulling. We made three sizing boxes. Thefirst is 1/4-inch hardware cloth [wire screen]. The second is two layers of1/4-inch cloth, moved slightly apart to narrow the opening in one direction, and the third is two layers of screen adjusted to make a still-smaller opening. Since the smallest unhulled seeds are about the size of the largest hulled kernels, the grading step prevents these undersized seeds from passing through unhulled. Processed together at a closer setting, the smallest seeds hulled out.Jim Eldon's workshop is littered with strange-looking pieces of apparatus. They represent initial attempts to build a workable winnowing box, using Kormier's vacuum exhaust idea for a source of air. Jim, Fred Matlack and Diana finally made a box with a Plexiglas front, through which they could observe what was happening.They cut a hole in the back of the box with a sliding cover to regulate the air pressure, and fiddled with various arrangements of baffles. The result was a stream of hulls exiting through one hole while the kernels fell to the bottom of the box. Now they were ready to try a five-pound sample of unhulled sunflower seeds to see how much they could recover.The five pounds were graded and dehulled, then winnowed. We got about one hull for every ten kernels in the final, winnowed product. These are easily picked out. They usually contain kernels still held behind the fibrous strings of the hull. Their weight prevents them from blowing out with the empty hulls. We found that bug-eaten seeds do blow away with the chaff, which was a bonus for cleanliness of the final product. Toss the hulls to the birds, who will find broken seeds among them.Starting with 80 ounces of unhulled seed, we ended up with 41-1/4 ounces of edible whole seeds, 1.8 ounces of damaged seeds suitable for animal feed, and 36.6 ounces of hulls. It took us about an hour. Notbad.Sunflower seeds store perfectly in the hulls, but they deteriorate more rapidly when shelled out. The grain mill dehuller and winnowing box give the gardener a way to have the freshest possible seeds for eating at all times of the year. With the construction of one more piece of equipment -- the oil press -- he can have absolutely fresh, unrefined, polyunsaturated sunflower oil for salads, mayonnaise and cooking.Most light, refined vegetable oils have been extracted using hexane, a form of naphtha. The oil is then heated to boil off the hexane. Lye is dumped into it. It's washed with steam, then heated to remove odors and taste before being laced with preservatives and stabilizers. It may feel oily in the mouth, but you might as well taste air. No so with fresh-made sunflower oil -- it's deliciously yet subtly nutty in flavor, adding unsurpassed flavor to salads.There's good reason to believe that sunflower oil may become the #1 vegetable oil in the U.S. in a few years. It's already #1 in health-conscious Europe. Corn oil has already caught on here for health reasons, and sunflower oil is so much better. Sunflower oil's 70 percent polyunsaturate is just under safflower, with corn oil bringing up the rear with 55 percent. And sunflowers yield 40 percent oil, soybeans only 20 percent.Our oil press isrelatively simple, but it must be welded together. Check the construction directions for details. The press consists of a welded tubular frame which accepts a three-ton hydraulic jack. You may already have one. If not, it can be purchased at most auto and hardware stores for about $16. A metal canister with holes drilled in its sides and one end welded shut holds the mashed sunflower seeds. A piston is inserted in the canister and then inverted and slipped over a pedestal on the frame. The jack is set in place, and the pressure gradually increased over half an hour. The oil drips from the sides of the canister into a tray -- the bottom of a plastic jug slipped over the pedestal works fine -- which empties the oil into a cup. You can filter the oil with a coffee filter to remove pieces of seed and other fine particles that would burn if the oil were used for cooking. If it's for salads or mayonnaise, there's no need to filter it.We first tried using "confectionary" sunflower seeds for oil. These are the regular eating kernels we're used to seeing. They give less than half as much oil as the oilseed types of sunflower. Although you can use confectionary types such as MAMMOTH RUS- SIAN for oil, don't expect to get more than an ounce and a half from a pound of seed. Oilseed produces three or more ounces of oil from a pound of seed and is well worth planting along with confectionary-type seeds. Oilseed has another big advantage -- to prepare it, you can put the whole, unhulled seed into a blender and whiz it until it forms a fine meal, while confectionary seeds must be dehulled first. The entire sequence of grading, dehulling and winnowing is avoided with oilseed.Oil types produce about a tenth of a pound of seed per head in commercial production. Gardeners, with their better soil and care, invariably do better than that. Our conservative estimate is that 1,280 plants will be enough for three gallons of oil. Spaced one foot apart in rows two feet apart, 1,280 oilseed plants will take a space 40-by-56 feet, or 80-by-28 if you want a more rectangular patch to face south.We worked in pound batches, since the canister just holds one pound of mash. After blending, we heated it to 170 degrees F. (77 deg C) by placing it in a 300-degree F. (149 deg C) oven and stirring it every five minutes for 20 minutes. Heating gets the oil flowing and doubles the yield of oil. In case you're wondering,"cold-pressed" oils sold commercially are also heated, and some are subjected to the entire chemical process. The term has no firm meaning within the industry, according to the literature we've surveyed.Heating does not change the structure of fats. It will not turn polyunsaturated fats into saturated fats. In fact, Dr. Donald R. Germann in his book, "TheAnti-Cancer Diet", says that "... an unsaturated fat must be heated to high temperatures -- above 425 degrees F. or 200 degrees C. -- at least 8 or 10 times before any shift toward saturation occurs..." Dean C. Fletcher, Ph.D., of the American Medical Association Department of Foods and Nutrition in Chicago, says, "It's true that either high temperature or repeated heatingdoes change the nature of some of the unsaturated oil molecules. (But) the flavor of the oil changes as these chemical changes occur, spoiling its taste. This effect is probably more profound than any of the physiological changes the altered oil might produce within the body."From 500 gm. of heated mash, we pressed 89 gm. of oil, 89 percent of the entire amount available and twice as much as we could press from unheated oil! The decision is up to you whether or not to heat the mash, but that extra 50 percent seems like an awful lot, especially when the whole technique is so labor intensive. The oil should be stored in the refrigerator, and it's probably best to use it within a month, since it has no preservatives. Mayonnaise made with such fresh oils should be kept refrigerated and used within two weeks. The leftover cake, still containing 50 percent of its oil, is a nutritious addition to your dishes, and makes excellent feed for animals or winter birds. Store the pressed cake in the freezer.We're talking then about a sunflower patch with two kinds of plants -- confectionary such as MAMMOTH RUSSIAN and oilseed such as PEREDOVIK. The oilseed plants should be grown 12 inches apart in rows two feet apart. Four average confectionary heads yield about a pound of unhulled seed. You'll need about 35 pounds of unhulled seed, or 140plants-worth, to yield 20 pounds of hulled kernels, about what a family of four will use in a year. That many plants can be grown in an area 26-by-10 feet. That's 260 square feet. Put that together with the 2,240 square feet for the oilseed sunflowers, and you need a patch about 2,500 square feet -- 25 100-foot rows -- to keep yourself supplied year-round with super nutrition and unsurpassable taste.Winnowing Machine For Sunflower SeedsThe winnowing machine operates on the age-old principle of blowing the chaff away from the heavy grain with a controlled current of air.The unit uses a household or shop-type vacuum cleaner for its air supply. A vacuum cleaner was used as a power source because it can supply a large volume of air over an extended period of time, and most homes and farms have a vacuum cleaner.A cloth bag has been attached to the chaff chute to catch the chaff as it is separated from the seed. The bag allows the hulls to be collected and greatly reduces the amount of waste material normally blown into the air by conventional systems.The unit has been constructed in such a way that the cloth bag and cleaner box can be placed inside the seed box, making a compact package for storage.Tools Required1. Table Saw2. Drill Press3. Band Saw4. Saber SawProcedure (cleaner box)1 . Cut out the two sides of the cleaner box from 1/4-inch plywood.2. Cut out the six interior pieces of the cleaner box from 3/4 x 3-1/2-inch select pine.3. Assemble the cleaner box elements with glue and nails.4. Cut four 1/4-inch square strips of pine four inches long.5. Glue the strips around the end of the chaff chute.6. Sand all surfaces and edges.7. Finish with clear lacquer finish.Procedure (seed box)1. Cut two pieces of pine /34" x 5 /12 x 15 inches for the sides.2. Cut two pieces of pine 3/4 x 5-1/2 x inches for the top and bottom.3. Plow a /14 x 1/4 groove for the front and back panels in all four pieces.4. Rip the top board to 5 inches so that the front panel can slide into the grooves in the side boards.5. Rabbet both ends of each 15-inch side piece to accept the top and bottom boards.6. Drill a hole in the left side board 2-1/2 inches from the top. The size of the hole is determined by the vacuum cleaner hose fitting.7. Cut a 3-1/4 x 4 inch hole in the top 1/2 inch from the right end. This hole will accept the cleaner box.8. Cut two pieces of pine for the baffle.9. Drill two 1-inch holes in the bottom of the baffle box.10. Cut a piece of 1/4 x 8-1/2 x 14 inch plywood for the back panel.11. Cut a 3-inch hole, centered 1-7/8 inches from the top and left sides of the plywood back.12. Assemble the sides, baffles, top, bottom, and back panel with glue and nails.13. Cut an 8-7/16 x 15-3/4-inch piece of Plexiglas for the front.14. Cut a one-inch radius on the top corners of the front.and sand the edges.15. Drill a one-inch thumb hole centered 7/8 inch from the top edge.16. Cut a 3-1/2-inch disk of 1/4-inch plywood for the vent cover.17. Drill a 3/16-inch hole 3/8 inch from the edge of the disk.18. Mount the disk over the vent with a #10 x 1-inch screw.19. Sand all surfaces and edges of the, box.20. Finish with clear lacquer finish.MaterialsCleaner Box2 -- 7-3/4 x 7-1/2 x 3/4" plywood (sides)6 -- 3/4 x 3-1/2 x 24" for all members (baffles)4 -- 1/4 x 1/4 x 4" pine (chute cleats)22 -- 1" x 18 ga. headed nailsWhite vinyl glueClear lacquer finishSeed Box2 -- 3/4' x 5-1/2 x 15" select pine (sides)2 -- 3/4 x 5-1/2 x 8-1/2" select pine (top and bottom)1 -- 3/4 x 3-1/2 x 4-1/2" select pine (baffle)1 -- 3/4 x 4-1/2 x 4-1/2" select pine (baffle)1 -- 1/4 x 8-1/2 x 14" plywood (back)1 -- 1/4 x 3-1/2" dia. plywood (control valve)1 -- 1/4' x 8-7/16 x 15-1/4" Plexiglas (front)1 - #10 x 1" flat head screw18 - 4d finish nailsWhite vinyl glueClear lacquer finish1 -- 17 x 31" cloth laundry bagSunflower Seed Oil PressThe press was designed so that homesteaders can produce sunflower oil from their own seeds. The oil can be pressed as is or heated to 170 degrees F., which doubles oil yield.Both methods require the seed to be ground to fine powder. If you are pressing the oil seed variety, a meat grinder or electric blender will do an excellent job of grinding the seed. The confectionary type of seed will require the seed to be hulled and winnowed before it is ground. A food mill with the stones set at the coarse setting can be used to accomplish this step. The ground kernels are placed in the cylinder with the piston closing the bottom portion of the cylinder.The cylinder is mounted in the press frame and a three-ton hydraulic jack is used to supply the pressure.Because of the great pressures created by the hydraulic jack, it is important that the frame be properly constructed and firmly mounted to the work surface before the pressing operation begins. The following instructions can be given to a welder.Tools Required1. Power Hacksaw2. Metal Band Saw3. Metal Lathe4. Drill Press5. Belt or Disk Grinder6. Arc Welder7. Hand ClampsProcedure (Frame)1. Cut two pieces of 1-3/4" O.D. x 1-3/8" I.D. x 24-1/2 inch long tubing for the uprights.2. Cut one piece of 1-3/4" O.D. x 1-3/8" I.D. x 6-1/2 inch long tubing for the center tube.3. Cut one 3/4" x 2-3/4 x 5-1/2 inch steel bar for the top cross member.4. Cut two pieces of 1-3/4 x 1-3/4 x 8 inch angle iron for the base members.5. Drill two 9/32-inch holes in each base member 1/2 inch from the outer edges.6. Weld the base members, tubes and cross member together as per the drawing.7. Grind all edges to remove any burrs.8. Paint the frame.9. If a mounting board is desired, cut a piece of pine 1-1/4 x 6-1/2 x 12 inches long.10. Center the frame on the board and mark the location of the four mounting holes.11. Drill four 7/8-inch holes 1/4-inch deep to accept the T-nuts.12. Drill four 5/16-inch holes through the mounting board using the same centers created by the 7/8-inch holes.13. Round the edges of the base and sand all surfaces.14. Install four 1/4-20 T-nuts.15. Finish the base with clear lacquer finish.16. Assemble the base to the frame using four 1/4-20 x 1-1/4-inch round head bolts.Procedure (Cylinder)1. Cut a piece of 3-1/2" O.D. x 3-1/4" I.D. tubing 5-3/8 inches long.2. Face both ends on the lathe.3. Cut out a 3-1/2-inch round disk from 1/4-inch plate steel.4. Weld the disk to one end of the tube.5. Drill a series of 3/32-inch holes around the side of the tube on 1/2-inch centers.6. Remove all burrs on the inside and outside of the tube.Procedure (Piston)1. Cut out a 3-3/8-inch disk of 1/4-inch plate steel.2. Cut a 1-3/8" O.D. x 1-1/8" I.D. piece of tubing 1-1/8 inches long.3. Face both ends of the tube.4. Weld the tube in the center of the 3-3/8-inch disk. All welds should be made on the inside of the tube.5. Mount the piston in the lathe and turn the disk to fit the inside diameter of the cylinder. This will be about 3-15/64 inches in diameter.6. Remove any sharp edges.Procedure (Collector Ring)1. Cut the bottom out of a one-gallon plastic bottle. The cut line should be approximately 1-1/2 inches from the bottom of the bottle.2. Make a 1/8 x 1 inch slot at one edge of the bottom outside ring. This will allow the oil to pour into a receiving cup.3. Cut a 1-3/4-inch hole in the center of the bottom, so that the unit will fit over the center tube in the frame.MaterialsFrame2 -- 1-3/4 O.D. x 1-3/8 I.D. x 24-1/2" long H.R.S. (frame tubes)1 -- 1-3/4 O.D. x 1-3/8 I.D. x 6-1/2 inch long H.R.S. (center tube)1 -- 3/4 x 2-3/4 x 5-1/2" flat bar H.R.S. (top cross member)2 -- 1-3/4 x 1-3/4 x 8" angle iron H.R.S. (base members)1 -- 1-1/4 x 6-1/2 x 12" #2 white pine (wood base)4 -- 1/4-20 x 1-1/4 R.H. mounting bolts4 -- 1/4-20 T-nutsBlack enamel for frame (finishing material)Clear lacquer finish for wood base3 -- 1/8" dia. welding rodsCylinder1 -- 1/4 x 3-1/2" dia. C.R.S. disk (top)1 -- 3-1/2 O.D. x 3-1/4 I.D. C.R.S. tube (cylinder)1 -- 1/8 dia. welding rodPiston1 -- 1/4 x 3-3/8 D.A. C.R.S. disk (piston top)1 -- 1-1/4 O.D. x 1 I.D. x 1" long H.R.S. (piston tube)1 -- 1/8 dia. welding rodCollector Ring1 -- Bottom from a one-gallon plastic bottle (oil collector ring)葵花籽脱壳机和油压机由Jeff考克斯-从有机园艺，1979年4月，罗代尔新闻2,500平方尺，一个四口之家每年可以长到足以产生三种葵花籽国产蔬菜沙拉或烹调油和20磅的营养丰富，适合脱皮加仑种子 - 与遗留养活一个冬天的产值，破碎的种子鸟类。

2016届本科毕业设计（论文）文献翻译题目宋体三号字，加粗学院宋体四号字专业宋体四号字班级宋体四号字学号宋体四号字姓名宋体四号字指导教师宋体四号字开题日期宋体四号字文献一：（宋体五号）英文题目(居中，Times New Roman字体，三号加粗)正文（英文不少于10000印刷符号，Times New Roman字体，五号，首行缩进2.5字符，单倍行距，两边对齐）翻译一：（宋体五号，另起一页）中文题目(居中，黑体，三号加粗)正文（中文不少于2000字，宋体，五号，单倍行距，首行缩进2字符）文献二：（宋体五号，另起一页）英文题目(居中，Times New Roman字体，三号加粗)正文（英文不少于10000印刷符号，Times New Roman字体，五号，首行缩进2.5字符，单倍行距，两边对齐）翻译二：（宋体五号，另起一页）中文题目(居中，黑体，三号加粗)正文（中文不少于2000字，宋体，五号，单倍行距，首行缩进2字符）（请参照下面模板）文献一：Research on Spillover Effect of Foreign Direct Investment1. IntroductionIn recent decades, economists have begun to identify technical progress, or more generally, knowledge creation, as the major determinant of economic growth. Until the 1970s, the analysis of economic growth was typically based on neoclassical models that explain growth with the accumulation of labor, capital, and other production factors with diminishing returns to scale. In these models, the economy converges to steady state equilibrium where the level of per capita income is determined by savings and investment, depreciation, and population growth, but where there is no permanent income growth. Any observed income growth per capita occurs because the economy is still converging towards its steady state, or because it is in transition from one steady state to another.The policies needed to achieve growth and development in the framework of these models is therefore straightforward: increases in savings and investments and reductions in the population growth rate, shift the economy to a higher steady state income level. From the view of developing countries, however, these policies are difficult to implement. Low income and development levels are not only consequences, but also causes of low savings and high population growth rates. The importance of technical progress was also recognized in the neoclassical growth models, but the determinants of the level of technology were not discussed in detail; instead, technology was seen as an exogenous factor. Yet, it was clear that convergence in income percapita levels could not occur unless technologies converged as well.From the 1980s and onwards, growth research has therefore increasingly focused on understanding and ontogenetic technical progress. Modern growth theory is largely built on models with constant or increasing returns to reproducible factors as a result of the accumulation of knowledge. Knowledge is, to some extent, a public good, and R&D, education, training, and other investments in knowledge creation may generate externalities that prevent diminishing returns to scale for labor and physical capital. Taking this into account, the economy may experience positive long-run growth instead of the neoclassical steady state where per capita incomes remain unchanged. Depending on the economic starting point, technical progress and growth can be based on creation of entirely new knowledge, or adaptation and transfer of existing foreign technology.Along with international trade, the most important vehicle for international technology transfer is foreign direct investment (FDI). It is well known that multinational corporations (MNCs) undertake a major part of the world’s private R&D efforts and production, own and control most of the world’s advanced technology. When a MNC sets up a forei gn affiliate, the affiliate receives some amount of the proprietary technology that constitutes the parent’s firm specific advantage and allows it to compete successfully with local firms that have superior knowledge of local markets, consumer preferences, and business practices. This leads to a geographical diffusion of technology, but not necessarily to any formal transfer of technology beyond the boundaries of the MNCs; the establishment of a foreign affiliate is, almost per definition, a decision to internalize the use of core technology.However, MNC technology may still leak to the surrounding economy through external effects or spillovers that raise the level of human capital in the host country and createproductivity increases in local firms. In many cases, the effects operate through forward and backward linkages, as MNCs provide training and technical assistance to their local suppliers, subcontractors, and customers. The labor market is another important channel for spillovers, as almost all MNCs train operatives and managers who may subsequently take employment in local firms or establish entirely new companies.It is therefore not surprising that attitudes towards inward FDI have changed considerably over the last couple of decades, as most countries have liberalized their policies to attract all kinds of foreign investment. Numerous governments have even introduced various forms of investment incentives to encourage foreign MNCs to invest in their jurisdiction. However, productivity and technology spillovers are not automatic consequences of FDI. Instead, FDI and human capital interact in a complex manner, where FDI inflows create a potential for spillovers of knowledge to the local labor force, at the same time as the host country’s level of human capital determines how much FDI it can attract and whether local firms are able to absorb the potential spillover benefits.2. Foreign Direct Investment and SpilloversThe earliest discussions of spillovers in the literature on foreign direct investment date back to the 1960s. The first author who systematically introduced spillovers (or external effects) among the possible consequences of FDI was MacDougall (1960), who analyzed the general welfare effects of foreign investment. The common aim of the studies was to identify the various costs and benefits of FDI.Productivity externalities were discussed together with several other indirect effects that influence the welfare assessment, such as those arising from the impact of FDI on government revenue, tax policies, terms of trade, and the balance of payments. The fact that spillovers included in the discussion was generally motivated by empirical evidence from case studies rather than by comprehensive theoretical arguments.Yet, the early analyses made clear that multinationals may improve locatives efficiency by entering into industries with high entry barriers and reducing monopolistic distortions, and induce higher technical efficiency if the increased competitive pressure or some demonstration effect spurs local firms to more efficient use of existing resources. They also proposed that the presence may lead to increases in the rate of technology transfer and diffusion. More specifically, case studies showed that foreign MNCs may:(1) Contribute to efficiency by breaking supply bottlenecks (but that the effect may become less important as the technology of the host country advances);(2) Introduce new know-how by demonstrating new technologies and training workers who later take employment in local firms;(3) Either break down monopolies and stimulate competition and efficiency or create a more monopolistic industry structure, depending on the strength and responses of the local firms;(4) Transfer techniques for inventory and quality control and standardization to their local suppliers and distribution channels;Although this diverse list gives some clues about the broad range of various spillover effects, it says little about how common or how important they are in general. Similar complaints can be made about the evidence on spillovers gauged from the numerous case studies discussing various aspects of FDI in different countries and industries. These studies often contain valuable circumstantial evidence of spillovers, but often fail to show how significant the spillover effectsare and whether the results can be generalized.For instance, many analyses of the linkages between MNCs and their local suppliers and subcontractors have documented learning and technology transfers that may make up a basis for productivity spillovers or market access spillovers. However, these studies seldom reveal whether the MNCs are able to extract all the benefits that the new technologies or information generate among their supplier firms. Hence, there is no clear proof of spillovers, but it is reasonable to assume that spillovers are positively related to the extent of linkages.Similarly, there are many works on the relation between MNCs entry and presence and market structure in host countries, and this is closely related to the possible effects of FDI on competition in the local markets. There are also case studies of demonstration effects, technology diffusion, and labor training in foreign MNCs. However, although these studies provide much detailed information about the various channels for spillovers, they say little about the overall significance of such spillovers.The statistical studies of spillovers, by contrast, may reveal the overall impact of foreign presence on the productivity of local firms, but they are generally not able to say much about how the effects come about. These studies typically estimate production functions for locally owned firms, and include the foreign share of the industry as one of the explanatory variables. They then test whether foreign presence has a significant positive impact on local productivity once other firm and industry characteristics have been accounted.Research conclude that domestic firms exhibited higher productivity in sectors with a larger foreign share, but argue that it may be wrong to conclude that spillovers have taken place if MNC affiliates systematically locate in the more productive sectors. In addition, they are also able to perform some more detailed tests of regional differences in spillovers. Examining the geographical dispersion of foreign investment, they suggest that the positive impact of FDI accrue mainly to the domestic firms located close to the MNC affiliates. However, effects seem to vary between industries.The results on the presence of spillovers seem to be mixed; recent studies suggest that there should be a systematic pattern where various host industry and host country characteristics influence the incidence of spillovers. For instance, the foreign affiliate’s levels of tech nology or technology imports seem to influence the amount of spillovers to local firms. The technology imports of MNC affiliates, in turn, have been shown to vary systematically with host country characteristics. These imports seem larger in countries and industries where the educational level of the local labor force is higher, where local competition is tougher, and where the host country imposes fewer formal requirements on the affiliates’ operations.Some recent studies have also addressed the apparent contradictions between the earlier statistical spillover studies, with the hypothesis that the host country’s level of technical development or human capital may matter as a starting point.In fact, in some cases, large foreign presence may even be a sign of a weak local industry, where local firms have not been able to absorb any productivity spillovers at all and have therefore been forced to yield market shares to the foreign MNCs.3. FDI Spillover and Human Capital DevelopmentThe transfer of technology from MNC parents to its affiliates and other host country firms is not only mbodied in machinery, equipment, patent rights, and expatriate managers and technicians,but is also realized rough the training of local employees. This training affects most levels of employees, from simple manufacturing operatives through supervisors to technically advanced professionals and top-level managers. While most recipients of training are employed in the MNCs own affiliates, the beneficiaries also include employees among the MNCs suppliers, subcontractors, and customers.Types of training ranged from on-the-job training to seminars and more formal schooling to overseas education, perhaps at the parent company, depending on the skills needed. The various skills gained through the elation with the foreign MNCs may spill over directly when the MNCs do not charge the full value of the training provided to local firms or over time, as the employees move to other firms or set up their own businesses.While the role of MNCs in primary and secondary education is marginal, there is increasingly clear evidence hat FDI may have a noticeable impact on tertiary education in their host countries. The most important effect is perhaps on the demand side. MNCs provide attractive employment opportunities to highly skilled graduates in natural sciences, engineering, and business sciences, which may be an incentive for gifted students to complete tertiary training, and MNCs demand skilled labor, which may encourage governments to invest in higher education.Many studies undertaken in developing countries have emphasized the spillovers of management skills. There is evidence of training and capacity development in technical areas, although the number of detailed studies appears smaller.While training activities in manufacturing often aim to facilitate the introduction of new technologies that are embodied in machinery and equipments, the training in service sectors is more directly focused on strengthening skills and know-how embodied in employees. This means that training and human capital development are often more important in service industries. Furthermore, many services are not tradable across international borders, which mean that service MNCs to a great extent are forced to reproduce home country technologies in their foreign affiliates. As a consequence, service companies are often forced to invest more in training, and the gap between affiliate and parent company wages tends, therefore, to be smaller than that in manufacturing.4. ConclusionThis paper has noted that the interaction of FDI and spillovers is complex and highly non-linear, and that several different outcomes are possible. FDI inflows create a potential for spillovers of knowledge to the local labor force, at the same time as the host country’s level of human capital determines how much FDI it can attract and whether local firms are able to absorb the potential spillover benefits. Hence, it is possible that host economies with relatively high levels of human capital may be able to attract large amounts of technology intensive foreign MNCs that contribute significantly to the further development of labor skills. At the same time, economies with weaker initial conditions are likely to experience smaller inflows of FDI, and those foreign firms that enter are likely to use simpler technologies that contribute only marginally to local learning and skill development.翻译一：外商直接投资溢出效应研究1.引言在最近几十年中，经济学家们已开始确定技术进步，或更普遍认为知识创造，作为经济增长原动力的一个重要决定因素，直到20世纪70年代，分析经济增长运用典型的新古典主义模型来解释经济增长的积累，劳动力、资本等生产要素与收益递减的规模。

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英文原文High Productivity —A Question of Shearer LoaderCutting SequencesK. Nienhaus, A. K. Bayer & H. Haut, Aachen University ofTechnology, GER1 AbstractRecently, the focus in underground longwall coal mining has been on increasing the installed motor power of shearer loaders and armoured face conveyors (AFC), more sophisticated support control systems and longer face length, in order to reduce costs and achieve higher productivity. These efforts have resulted in higher output and previously unseen face advance rates. The trend towards “bigger and better” equipment and layout schemes, however, is rapidly nearing the limitations of technical and economical feasibility. To realise further productivity increases, organisational changes of longwall mining procedures looks like the only reasonable answer. The benefits of opti-mised shearer loader cutting sequences, leading to better performance, are discussed in this paper.2 IntroductionsTraditionally, in underground longwall mining operations, shearer loaders produce coal using either one of the following cutting sequences: uni-directional or bi-directional cycles. Besides these pre-dominant methods, alternative mining cycles have also been developed and successfully applied in underground hard coal mines all over the world. The half-web cutting cycle as e.g. utilized in RAG Coal International’s Twentymile Mine in Colorado, USA, and the “Opti-Cycle” of Matla’s South African shortwall operation must be mentioned in this context. Other mines have also tested similar but modified cutting cycles resulting inimproved output, e.g. improvements in terms of productiv-ity increases of up to 40 % are thought possible。