外文翻译原文一
塑料注塑模具中英文对照外文翻译文献

外文翻译及原文(文档含英文原文和中文翻译)【原文一】CONCURRENT DESIGN OF PLASTICS INJECTION MOULDS AbstractThe plastic product manufacturing industry has been growing rapidly in recent years. One of the most popular processes for making plastic parts is injection moulding. The design of injection mould is critically important to product quality and efficient product processing.Mould-making companies, who wish to maintain the competitive edge, desire to shorten both design and manufacturing leading times of the by applying a systematic mould design process. The mould industry is an important support industry during the product development process, serving as an important link between the product designer and manufacturer. Product development has changed from the traditional serial process of design, followed by manufacture, to a more organized concurrent process where design and manufacture are considered at a very early stage of design. The concept of concurrent engineering (CE) is no longer new and yet it is still applicable and relevant in today’s manuf acturing environment. Team working spirit, management involvement, total design process and integration of IT tools are still the essence of CE. The application of The CE process to the design of an injection process involves the simultaneous consideration of plastic part design, mould design and injection moulding machine selection, production scheduling and cost as early as possible in the design stage.This paper presents the basic structure of an injection mould design. The basis of this system arises from an analysis of the injection mould design process for mould design companies. This injection mould design system covers both the mould design process and mould knowledge management. Finally the principle of concurrent engineering process is outlined and then its principle is applied to the design of a plastic injection mould.Keywords :Plastic injection mould design, Concurrent engineering, Computer aided engineering, Moulding conditions, Plastic injection moulding, Flow simulation1.IntroductionInjection moulds are always expensive to make, unfortunately without a mould it can not be possible ho have a moulded product. Every mould maker has his/her own approach to design a mould and there are many different ways of designing and building a mould. Surely one of the most critical parameters to be considered in the design stage of the mould is the number of cavities, methods of injection, types of runners, methods of gating, methods of ejection, capacity and features of the injection moulding machines. Mould cost, mould quality and cost of mould product are inseparableIn today’s completive environment, computer aided mould filling simulation packages can accurately predict the fill patterns of any part. This allows for quick simulations of gate placements and helps finding the optimal location. Engineers can perform moulding trials on the computer before the part design is completed. Process engineers can systematically predict a design and process window, and can obtain information about the cumulative effect of the process variables that influence part performance, cost, and appearance.2.Injection MouldingInjection moulding is one of the most effective ways to bring out the best in plastics. It is universally used to make complex, finished parts, often in a single step, economically, precisely and with little waste. Mass production of plastic parts mostly utilizes moulds. The manufacturing process and involving moulds must be designed after passing through the appearance evaluation and the structure optimization of the product design. Designers face a hugenumber of options when they create injection-moulded components. Concurrent engineering requires an engineer to consider the manufacturing process of the designed product in the development phase. A good design of the product is unable to go to the market if its manufacturing process is impossible or too expensive. Integration of process simulation, rapid prototyping and manufacturing can reduce the risk associated with moving from CAD to CAM and further enhance the validity of the product development.3. Importance of Computer Aided Injection Mould DesignThe injection moulding design task can be highly complex. Computer Aided Engineering (CAE) analysis tools provide enormous advantages of enabling design engineers to consider virtually and part, mould and injection parameters without the real use of any manufacturing and time. The possibility of trying alternative designs or concepts on the computer screen gives the engineers the opportunity to eliminate potential problems before beginning the real production. Moreover, in virtual environment, designers can quickly and easily asses the sensitivity of specific moulding parameters on the quality and manufacturability of the final product. All theseCAE tools enable all these analysis to be completed in a meter of days or even hours, rather than weeks or months needed for the real experimental trial and error cycles. As CAE is used in the early design of part, mould and moulding parameters, the cost savings are substantial not only because of best functioning part and time savings but also the shortens the time needed to launch the product to the market.The need to meet set tolerances of plastic part ties in to all aspects of the moulding process, including part size and shape, resin chemical structure, the fillers used, mould cavity layout, gating, mould cooling and the release mechanisms used. Given this complexity, designers often use computer design tools, such as finite element analysis (FEA) and mould filling analysis (MFA), to reduce development time and cost. FEA determines strain, stress and deflection in a part by dividing the structure into small elements where these parameters can be well defined. MFA evaluates gate position and size to optimize resin flow. It also defines placement of weld lines, areas of excessive stress, and how wall and rib thickness affect flow. Other finite element design tools include mould cooling analysis for temperature distribution, and cycle time and shrinkage analysis for dimensional control and prediction of frozen stress and warpage.The CAE analysis of compression moulded parts is shown in Figure 1. The analysis cycle starts with the creation of a CAD model and a finite element mesh of the mould cavity. After the injection conditions are specified, mould filling, fiber orientation, curing and thermal history, shrinkage and warpage can be simulated. The material properties calculated by the simulation can be used to model the structural behaviour of the part. If required, part design, gate location and processing conditions can be modified in the computer until an acceptable part is obtained. After the analysis is finished an optimized part can be produced with reduced weldline (known also knitline), optimized strength, controlled temperatures and curing, minimized shrinkage and warpage.Machining of the moulds was formerly done manually, with a toolmaker checking each cut. This process became more automated with the growth and widespread use of computer numerically controlled or CNC machining centres. Setup time has also been significantly reduced through the use of special software capable of generating cutter paths directly from a CAD data file. Spindle speeds as high as 100,000 rpm provide further advances in high speed machining. Cutting materials have demonstrated phenomenal performance without the use of any cutting/coolant fluid whatsoever. As a result, the process of machining complex cores and cavities has been accelerated. It is good news that the time it takes to generate a mould is constantly being reduced. The bad news, on the other hand, is that even with all these advances, designing and manufacturing of the mould can still take a long time and can be extremely expensive.Figure 1 CAE analysis of injection moulded partsMany company executives now realize how vital it is to deploy new products to market rapidly. New products are the key to corporate prosperity. They drive corporate revenues, market shares, bottom lines and share prices. A company able to launch good quality products with reasonable prices ahead of their competition not only realizes 100% of the market before rival products arrive but also tends to maintain a dominant position for a few years even after competitive products have finally been announced (Smith, 1991). For most products, these two advantages are dramatic. Rapid product development is now a key aspect of competitive success. Figure 2 shows that only 3–7% of the product mix from the average industrial or electronics company is less than 5 years old. For companies in the top quartile, the number increases to 15–25%. For world-class firms, it is 60–80% (Thompson, 1996). The best companies continuously develop new products. AtHewlett-Packard, over 80% of the profits result from products less than 2 years old! (Neel, 1997)Figure 2. Importance of new product (Jacobs, 2000)With the advances in computer technology and artificial intelligence, efforts have been directed to reduce the cost and lead time in the design and manufacture of an injection mould. Injection mould design has been the main area of interest since it is a complex process involving several sub-designs related to various components of the mould, each requiring expert knowledge and experience. Lee et. al. (1997) proposed a systematic methodology and knowledge base for injection mould design in a concurrent engineering environment.4.Concurrent Engineering in Mould DesignConcurrent Engineering (CE) is a systematic approach to integrated product development process. It represents team values of co-operation, trust and sharing in such a manner that decision making is by consensus, involving all per spectives in parallel, from the very beginning of the productlife-cycle (Evans, 1998). Essentially, CE provides a collaborative, co-operative, collective and simultaneous engineering working environment. A concurrent engineering approach is based on five key elements:1. process2. multidisciplinary team3. integrated design model4. facility5. software infrastructureFigure 3 Methodologies in plastic injection mould design, a) Serial engineering b) Concurrent engineeringIn the plastics and mould industry, CE is very important due to the high cost tooling and long lead times. Typically, CE is utilized by manufacturing prototype tooling early in the design phase to analyze and adjust the design. Production tooling is manufactured as the final step. The manufacturing process and involving moulds must be designed after passing through the appearance evaluation and the structure optimization of the product design. CE requires an engineer to consider the manufacturing process of the designed product in the development phase.A good design of the product is unable to go to the market if its manufacturing process is impossible. Integration of process simulation and rapid prototyping and manufacturing can reduce the risk associated with moving from CAD to CAM and further enhance the validity of the product development.For years, designers have been restricted in what they can produce as they generally have todesign for manufacture (DFM) – that is, adjust their design intent to enable the component (or assembly) to be manufactured using a particular process or processes. In addition, if a mould is used to produce an item, there are therefore automatically inherent restrictions to the design imposed at the very beginning. Taking injection moulding as an example, in order to process a component successfully, at a minimum, the following design elements need to be taken into account:1. . geometry;. draft angles,. Non re-entrants shapes,. near constant wall thickness,. complexity,. split line location, and. surface finish,2. material choice;3. rationalisation of components (reducing assemblies);4. cost.In injection moulding, the manufacture of the mould to produce the injection-moulded components is usually the longest part of the product development process. When utilising rapid modelling, the CAD takes the longer time and therefore becomes the bottleneck.The process design and injection moulding of plastics involves rather complicated and time consuming activities including part design, mould design, injection moulding machine selection, production scheduling, tooling and cost estimation. Traditionally all these activities are done by part designers and mould making personnel in a sequential manner after completing injection moulded plastic part design. Obviously these sequential stages could lead to long product development time. However with the implementation of concurrent engineering process in the all parameters effecting product design, mould design, machine selection, production scheduling,tooling and processing cost are considered as early as possible in the design of the plastic part. When used effectively, CAE methods provide enormous cost and time savings for the part design and manufacturing. These tools allow engineers to virtually test how the part will be processed and how it performs during its normal operating life. The material supplier, designer, moulder and manufacturer should apply these tools concurrently early in the design stage of the plastic parts in order to exploit the cost benefit of CAE. CAE makes it possible to replace traditional, sequential decision-making procedures with a concurrent design process, in which all parties can interact and share information, Figure 3. For plastic injection moulding, CAE and related design data provide an integrated environment that facilitates concurrent engineering for the design and manufacture of the part and mould, as well as material selection and simulation of optimal process control parameters.Qualitative expense comparison associated with the part design changes is shown in Figure 4 , showing the fact that when design changes are done at an early stages on the computer screen, the cost associated with is an order of 10.000 times lower than that if the part is in production. These modifications in plastic parts could arise fr om mould modifications, such as gate location, thickness changes, production delays, quality costs, machine setup times, or design change in plastic parts.Figure 4 Cost of design changes during part product development cycle (Rios et.al, 2001)At the early design stage, part designers and moulders have to finalise part design based on their experiences with similar parts. However as the parts become more complex, it gets rather difficult to predict processing and part performance without the use of CAE tools. Thus for even relatively complex parts, the use of CAE tools to prevent the late and expensive design changesand problems that can arise during and after injection. For the successful implementation of concurrent engineering, there must be buy-in from everyone involved.5.Case StudyFigure 5 shows the initial CAD design of plastics part used for the sprinkler irrigation hydrant leg. One of the essential features of the part is that the part has to remain flat after injection; any warping during the injection causes operating problems.Another important feature the plastic part has to have is a high bending stiffness. A number of feeders in different orientation were added to the part as shown in Figure 5b. These feeders should be designed in a way that it has to contribute the weight of the part as minimum aspossible.Before the design of the mould, the flow analysis of the plastic part was carried out with Moldflow software to enable the selection of the best gate location Figure 6a. The figure indicates that the best point for the gate location is the middle feeder at the centre of the part. As the distortion and warpage of the part after injection was vital from the functionality point of view and it has to be kept at a minimum level, the same software was also utilised to yiled the warpage analysis. Figure 5 b shows the results implying the fact that the warpage well after injection remains within the predefined dimensional tolerances.6. ConclusionsIn the plastic injection moulding, the CAD model of the plastic part obtained from commercial 3D programs could be used for the part performance and injection process analyses. With the aid ofCEA technology and the use of concurrent engineering methodology, not only the injection mould can be designed and manufactured in a very short of period of time with a minimised cost but also all potential problems which may arise from part design, mould design and processing parameters could be eliminated at the very beginning of the mould design. These two tools help part designers and mould makers to develop a good product with a better delivery and faster tooling with less time and money.References1. Smith P, Reinertsen D, The time-to-market race, In: Developing Products in Half the Time. New York, Van Nostrand Reinhold, pp. 3–13, 19912.Thompson J, The total product development organization. Proceedings of the SecondAsia–Pacific Rapid Product Development Conference, Brisbane, 19963.Neel R, Don’t stop after the prototype, Seventh International Conference on Rapid Prototyping, San Francisco, 19974.Jacobs PF, “Chapter 3: Rapid Product Development” in Rapid Tooling: Technologies and Industrial Applications , Ed. Peter D. Hilton; Paul F. Jacobs, Marcel Decker, 20005.Lee R-S, Chen, Y-M, and Lee, C-Z, “Development of a concurrent mould design system: a knowledge based approach”, Computer Integrated Manufacturing Systems, 10(4), 287-307, 19976.Evans B., “Simultaneous Engineering”, Mechanical Engi neering , V ol.110, No.2, pp.38-39, 19987.Rios A, Gramann, PJ and Davis B, “Computer Aided Engineering in Compression Molding”, Composites Fabricators Association Annual Conference , Tampa Bay, 2001【译文一】塑料注塑模具并行设计塑料制品制造业近年迅速成长。
外文翻译1

译文(一)THE ACCOUNTING REVIEWV ol. 83, No. 3 2008pp. 823–853市场参与者的杜邦分析的使用马克•t•Soliman华盛顿大学文摘:杜邦分析,一种常见的财务报表分析,依靠于净营业资产收益率的两个乘法组件:利润率和资产周转率。
这两个会计比率衡量不同的构造。
因此,有不同的属性。
之前的研究已经发现,资产周转率的变化是未来收益的变化正相关。
本文全面探讨了杜邦组件和沿着三个维度有助于文学。
首先,本文有助于财务报表分析文献,发现在这个会计信息信号实际上是增量学习会计信号在先前的研究在预测未来收益。
其次,它有助于文学在股票市场上使用的会计信息通过检查眼前和未来的股本回报投资者应对这些组件。
最后,它增加了分析师的文献处理会计信息的再次测试直接和延迟反应的分析师通过同期预测修正以及未来预测错误。
一致的跨市场加入者的两组,结果表明是有用的信息就是明证杜邦组件和股票收益之间的联系以及维度分析师预测。
然而,我发现预测未来预测错误和异常返回信息处理表明似乎没有完成。
平均水平,分析表明杜邦组件代表增量和可行的操作特征信息的公司。
关键词:财务报表分析、杜邦分析、市场回报、分析师预估。
数据可用性:在这项研究中使用的数据是公开的来源显示的文本。
在本文中,我分析杜邦分析中包含的信息是否与股市回报相关和分析师预测。
之前的研究文档组件从杜邦分析,分解的净营业资产收益率为利润率和资产周转率,有解释力对未来盈利能力的变化。
本文增加了文献综合研究投资者和分析师反应杜邦组件三个维度。
首先,它复制先前记录的预测能力和检查是否健壮和增量其他预测已经考虑在文学的存在。
其次,它探讨了使用这些组件的股市投资者通过观察同生和未来收益。
在同时代的长窗协会和短时期限信息测试,结果显示积极联系杜邦组件和股本回报率。
但小未来异常返回交易策略显示的信息可能不完整的处理。
最后,检查当前预测修正由卖方分析师和未来的预测错误。
外文文献翻译(图片版)

本科毕业论文外文参考文献译文及原文学院经济与贸易学院专业经济学(贸易方向)年级班别2007级 1 班学号3207004154学生姓名欧阳倩指导教师童雪晖2010 年 6 月 3 日目录1 外文文献译文(一)中国银行业的改革和盈利能力(第1、2、4部分) (1)2 外文文献原文(一)CHINA’S BANKING REFORM AND PROFITABILITY(Part 1、2、4) (9)1概述世界银行(1997年)曾声称,中国的金融业是其经济的软肋。
当一国的经济增长的可持续性岌岌可危的时候,金融业的改革一直被认为是提高资金使用效率和消费型经济增长重新走向平衡的必要(Lardy,1998年,Prasad,2007年)。
事实上,不久前,中国的国有银行被视为“技术上破产”,它们的生存需要依靠充裕的国家流动资金。
但是,在银行改革开展以来,最近,强劲的盈利能力已恢复到国有商业银行的水平。
但自从中国的国有银行在不久之前已经走上了改革的道路,它可能过早宣布银行业的改革尚未取得完全的胜利。
此外,其坚实的财务表现虽然强劲,但不可持续增长。
随着经济增长在2008年全球经济衰退得带动下已经开始软化,银行预计将在一个比以前更加困难的经济形势下探索。
本文的目的不是要评价银行业改革对银行业绩的影响,这在一个完整的信贷周期后更好解决。
相反,我们的目标是通过审查改革的进展和银行改革战略,并分析其近期改革后的强劲的财务表现,但是这不能完全从迄今所进行的改革努力分离。
本文有三个部分。
在第二节中,我们回顾了中国的大型国有银行改革的战略,以及其执行情况,这是中国银行业改革的主要目标。
第三节中分析了2007年的财务表现集中在那些在市场上拥有浮动股份的四大国有商业银行:中国工商银行(工商银行),中国建设银行(建行),对中国银行(中银)和交通银行(交通银行)。
引人注目的是中国农业银行,它仍然处于重组上市过程中得适当时候的后期。
第四节总结一个对银行绩效评估。
注塑模具设计外文翻译

毕业设计(论文)外文资料翻译及原文(2012届)题目电话机三维造型与注塑模具设计指导教师院系工学院班级学号姓名二〇一一年十二月六日【译文一】塑料注塑模具并行设计Assist.Prof.Dr. A. Y AYLA /Prof.Dr. Paş a YAYLA摘要塑料制品制造业近年迅速成长。
其中最受欢迎的制作过程是注塑塑料零件。
注塑模具的设计对产品质量和效率的产品加工非常重要。
模具公司想保持竞争优势,就必须缩短模具设计和制造的周期。
模具是工业的一个重要支持行业,在产品开发过程中作为一个重要产品设计师和制造商之间的联系。
产品开发经历了从传统的串行开发设计制造到有组织的并行设计和制造过程中,被认为是在非常早期的阶段的设计。
并行工程的概念(CE)不再是新的,但它仍然是适用于当今的相关环境。
团队合作精神、管理参与、总体设计过程和整合IT工具仍然是并行工程的本质。
CE过程的应用设计的注射过程包括同时考虑塑件设计、模具设计和注塑成型机的选择、生产调度和成本中尽快设计阶段。
介绍了注射模具的基本结构设计。
在该系统的基础上,模具设计公司分析注塑模具设计过程。
该注射模设计系统包括模具设计过程及模具知识管理。
最后的原则概述了塑料注射模并行工程过程并对其原理应用到设计。
关键词:塑料注射模设计、并行工程、计算机辅助工程、成型条件、塑料注塑、流动模拟1、简介注塑模具总是昂贵的,不幸的是没有模具就不可能生产模具制品。
每一个模具制造商都有他/她自己的方法来设计模具,有许多不同的设计与建造模具。
当然最关键的参数之一,要考虑到模具设计阶段是大量的计算、注射的方法,浇注的的方法、研究注射成型机容量和特点。
模具的成本、模具的质量和制件质量是分不开的在针对今天的计算机辅助充型模拟软件包能准确地预测任何部分充填模式环境中。
这允许快速模拟实习,帮助找到模具的最佳位置。
工程师可以在电脑上执行成型试验前完成零件设计。
工程师可以预测过程系统设计和加工窗口,并能获得信息累积所带来的影响,如部分过程变量影响性能、成本、外观等。
外文文献翻译译稿

外文文献翻译译稿1可用性和期望值来自Willliam S.Green, Patrick W.Jordan.产品的愉悦:超越可用性根据人机工程学会(HFES)的观点,人机工程学着眼于“发现和共享可用于各种系统和设备设计的、关于人的特点的知识”。
人们通常只是把它作为生物力学和人体测量所关注的内容,实际上它是从更广泛的意义上的一种对人(产品用户)的全面和综合的理解。
HFES从二战中有军方从事的系统分析中发展而来。
其中的三种主要研究的是人体测量、复杂信息的解释和管理,以及在部队和装备调配中应用的系统分析。
系统分析在尺度和复杂性方面跨度很大,大的系统分析有类似于诺曼底登陆准备的大型系统规划,小到去理解如何从合理性和规模的角度才最佳的布置和装备人员。
诺曼底登陆是20世纪最复杂的事件之一。
他要求建立一个在战斗开始之前还不确定的庞大的人员和物资的合理分配系统。
在更小的规模上,装备和军事人物的布置意味着如何去组织、训练和安排战士,最大限度的发挥他们的长处。
士兵必须迅速地接受训练,并且能够有效地使用和维护在二战中发展起来的一系列技术装备。
其中,对于飞行员、潜艇人员和坦克驾驶员有神采的限制。
复杂的新装备的开发要求找到最好的税收、密码便医院、破译人员、雷达和声纳操作员、轰炸机驾驶员和机组人员。
在战后,随着公司及其产品在尺度、领域和复杂性方面的增长,很多系统分析人员在商用领域找到了发展机会。
尽管是战后的发展才导致了1957年人机工程协会(HFES)的建立,但人机研究的起源可以追溯到大批量生产方式的成型阶段,是当时提高生产效率的要求。
随着工作方式从手工生产和农业生产中的转移,新的工厂工作的概念逐步发展起来。
福特的流水生产线和泰勒的效率理论开始对生产的规划和教育产生影响。
即使在家庭生活中,妇女们也开始接受了现代家庭管理理论,并运用这些理论来组织和规划家庭。
在20世纪末,一种涵盖面更广的人机工程正在发展之中。
新的人机工程学是为了适应已经被广泛意识到的对用户行为模式更深入的需求而诞生的,它开始应用定型研究方法,并探索人的情感和认知因素。
外文文献翻译译稿和原文【范本模板】

外文文献翻译译稿1卡尔曼滤波的一个典型实例是从一组有限的,包含噪声的,通过对物体位置的观察序列(可能有偏差)预测出物体的位置的坐标及速度。
在很多工程应用(如雷达、计算机视觉)中都可以找到它的身影。
同时,卡尔曼滤波也是控制理论以及控制系统工程中的一个重要课题。
例如,对于雷达来说,人们感兴趣的是其能够跟踪目标.但目标的位置、速度、加速度的测量值往往在任何时候都有噪声。
卡尔曼滤波利用目标的动态信息,设法去掉噪声的影响,得到一个关于目标位置的好的估计.这个估计可以是对当前目标位置的估计(滤波),也可以是对于将来位置的估计(预测),也可以是对过去位置的估计(插值或平滑).命名[编辑]这种滤波方法以它的发明者鲁道夫。
E。
卡尔曼(Rudolph E. Kalman)命名,但是根据文献可知实际上Peter Swerling在更早之前就提出了一种类似的算法。
斯坦利。
施密特(Stanley Schmidt)首次实现了卡尔曼滤波器。
卡尔曼在NASA埃姆斯研究中心访问时,发现他的方法对于解决阿波罗计划的轨道预测很有用,后来阿波罗飞船的导航电脑便使用了这种滤波器。
关于这种滤波器的论文由Swerling(1958)、Kalman (1960)与Kalman and Bucy(1961)发表。
目前,卡尔曼滤波已经有很多不同的实现.卡尔曼最初提出的形式现在一般称为简单卡尔曼滤波器。
除此以外,还有施密特扩展滤波器、信息滤波器以及很多Bierman, Thornton开发的平方根滤波器的变种.也许最常见的卡尔曼滤波器是锁相环,它在收音机、计算机和几乎任何视频或通讯设备中广泛存在。
以下的讨论需要线性代数以及概率论的一般知识。
卡尔曼滤波建立在线性代数和隐马尔可夫模型(hidden Markov model)上.其基本动态系统可以用一个马尔可夫链表示,该马尔可夫链建立在一个被高斯噪声(即正态分布的噪声)干扰的线性算子上的。
系统的状态可以用一个元素为实数的向量表示.随着离散时间的每一个增加,这个线性算子就会作用在当前状态上,产生一个新的状态,并也会带入一些噪声,同时系统的一些已知的控制器的控制信息也会被加入。
外文翻译--创业板市场

外文文献翻译译文一、外文原文原文:China's Second BoardI. Significance of and events leading to the establishment of a Second BoardOn 31 March 2009 the China Securities Regulatory Commission (CSRC issued Interim Measures on the Administration of Initial Public Offerings and Listings of Shares on the ChiNext [i.e., the Second Board, also called the Growth Enterprise Market] ("Interim Measures"), which came into force on 1 May 2009. This marked the creation by the Shenzhen Stock Exchange of the long-awaited market for venture businesses. As the original plan to establish such a market in 2001 had come to nothing when the dotcom bubble burst, the market's final opening came after a delay of nearly 10 years.Ever since the 1980s, when the Chinese government began to foster the development of science and technology, venture capital has been seen in China as a means of supporting the development of high-tech companies financially. The aim, as can be seen from the name of the 1996 Law of the People's Republic of China on Promoting the Conversion of Scientific and Technological Findings into Productivity ,was to support the commercialization of scientific and technological developments. Venture capital funds developed gradually in the late 1990s, and between then and 2000 it looked increasingly likely that a Second Board would be established. When the CSRC published a draft plan for this in September 2000, the stage was set. However, when the dotcom bubble (and especially the NASDAQ bubble) burst, this plan was shelved. Also, Chinese investors and venture capitalists were probably not quite ready for such a move.As a result, Chinese venture businesses sought to list on overseas markets (a so-called "red chip listing") from the late 1990s. However, as these listings increased, so did the criticism that valuable Chinese assets were being siphoned overseas.On thepolicy front, in 2004 the State Council published Some Opinions on Reform, Opening and Steady Growth of Capital Markets ("the Nine Opinions"), in which the concept of a "multi-tier capital market" was presented for the first time. A first step in this direction was made in the same year, when an SME Board was established as part of the Main Board. Although there appear to have been plans to eventually relax the SME Board's listing requirements, which were the same as those for companies listed on the Main Board, and to make it a market especially for venture businesses, it was decided to establish a separate market (the Second Board) for this purpose and to learn from the experience of the SME Board.As well as being part of the process of creating a multi-tier capital market, the establishment of the Second Board was one of the measures included in the policy document Several Opinions of the General Office of the State Council on Providing Financing Support for Economic Development ("the 30 Financial Measures"), published in December 2008 in response to the global financial crisis and intended as a way of making it easier for SMEs to raise capital.It goes without saying that the creation of the Second Board was also an important development in that it gives private equity funds the opportunity to exit their investments. The absence of such an exit had been a disincentive to such investment, with most funds looking for a red chip listing as a way of exiting their investments. However, with surplus savings at home, the Chinese authorities began to encourage companies to raise capital on the domestic market rather than overseas. This led, in September 2006, to a rule making it more difficult for Chinese venture businesses to list their shares on overseas markets. The corollary of this was that it increased the need for a means whereby Chinese private equity funds could exit their investments at an early opportunity and on their own market. The creation of the Second Board was therefore a belated response to this need.II. Rules and regulations governing the establishment of the Second BoardWe now take a closer look at some of the rules and regulations governing the establishment of the Second Board.First , the Interim Measures on the Administration of Initial Public Offerings andListings of Shares on the ChiNext, issued by the CSRC on 31 March 2009 with effect from 1 May 2009. The Interim Measures consist of six chapters and 58 articles, stipulating issue terms and procedures, disclosure requirements, regulatory procedures, and legal responsibilities.First, the General Provisions chapter. The first thing this says (Article 1) is: "These Measures are formulated for the purposes of promoting the development of innovative enterprises and other growing start-ups" This shows that one of the main listing criteria is a company's technological innovativeness and growth potential. The Chinese authorities have actually made it clear that, although the Second Board and the SME Board are both intended for SMEs of similar sizes, the Second Board is specifically intended for SMEs at the initial (rather than the growth or mature) stage of their development with a high degree of technological innovativeness and an innovative business model while the SME Board is specifically intended for companies with relatively stable earnings at the mature stage of their development. They have also made it clear that the Second Board is not simply a "small SME Board." This suggests to us that the authorities want to see technologically innovative companies listing on the Second Board and SMEs in traditional sectors listing on the SME Board.Next, Article 7 says: "A market access system that is commensurate with the risk tolerance of investors shall be established for investors on the ChiNext and investment risk shall be fully disclosed to investors." One noteworthy feature is the adoption of the concept of the "qualified investor" in an attempt to improve risk control.Furthermore, Article 8 says: "China Securities Regulatory Commission (hereinafter, CSRC) shall, in accordance with law, examine and approve the issuer’s IPO application and supervise the issuer’s IPO activities. The stock exchange shall formulate rules in accordance with law, provide an open, fair and equitable market environment and ensure the normal operation of the ChiNext." Until the Second Board was established, it was thought by some that the stock exchange had the right to approve new issues. Under the Interim Measures, however, it is the CSRC that examines and approves applications.First, offering conditions. Article 10 stipulates four numerical conditions for companies applying for IPOs.Second, offering procedures. The Interim Measures seek to make sponsoring securities companies more responsible by requiring them to conduct due diligence investigations and make prudential judgment on the issuer’s growth and render special opinions thereon.Third, information disclosure. Article 39 of the Interim Measures stipulates that the issuer shall make a statement in its prospectus pointing out the risks of investing in Second Board companies: namely, inconsistent performance, high operational risk, and the risk of delisting. Similarly,Fourth, supervision. Articles 51 and 52 stipulate that the stock exchange (namely, the Shenzhen Stock Exchange) shall establish systems for listing, trading and delisting Second Board stocks, urge sponsors to fulfill their ongoing supervisory obligations, and establish a market risk warning system and an investor education system.1. Amendments to the Interim Measures on Securities Issuance and Listing Sponsor System and the Provisional Measures of the Public Offering Review Committee of the China Securities Regulatory Commission2. Rules Governing the Listing of Shares on the ChiNext of Shenzhen Stock Exchange Next, the Shenzhen Stock Exchange published Rules Governing the Listing of Shares on the ChiNext of Shenzhen Stock Exchange on 6 June (with effect from 1 July).3. Checking investor eligibility As the companies listed on the Second Board are more risky than those listed on the Main Board and are subject to more rigorous delisting rules (see above), investor protection requires that checks be made on whether Second Board shares are suitable for all those wishing to invest in them.4. Rules governing (1) application documents for listings on the ChiNext and (2) prospectuses of ChiNext companies On 20 July the CSRC published rules governing Application Documents for Initial Public Offerings and Listings of Shares on the ChiNext and Prospectuses of ChiNext Companies, and announced that it would begin processing listing applications on 26 July.III. Future developmentsAs Its purpose is to "promote the development of innovative enterprises and other growing start-ups",the Second Board enables such companies to raise capital by issuing shares. That is why its listing requirements are less demanding than those of the Main Board but also why it has various provisions to mitigate risk. For one thing, the Second Board has its own public offering review committee to check how technologically specialized applicant companies are, reflecting the importance attached to this. For another, issuers and their controlling shareholders, de facto controllers, and sponsoring securities companies are subject to more demanding accountability requirements. The key factor here is, not surprisingly, disclosure. Also, the qualified investor system is designed to mitigate the risks to retail investors.Once the rules and regulations governing the Second Board were published, the CSRC began to process listing applications from 26 July 2009. It has been reported that 108 companies initially applied. As of mid-October, 28 of these had been approved and on 30 October they were listed on the Second Board.As of 15 December, there are 46 companies whose listing application has been approved by CSRC (including the above-mentioned 28 companies). They come from a wide range of sectors, especially information technology, services, and biopharmacy. Thus far, few companies in which foreign private equity funds have a stake have applied. This is because these funds have tended to go for red-chip listings.Another point is movement between the various tiers of China's multi-tier capital market. As of early September, four companies that are traded on the new Third Board had successfully applied to list on the Second Board. As 22 new Third Board companies meet the listing requirements of the Second Board on the basis of their interim reports for the first half of fiscal 2009, a growing number of companies may transfer their listing from the new Third Board to the Second Board. We think this is likely to make the new Third Board a more attractive market for private equity investors.The applicants include companies that were in the process of applying for a listing on the SME Board. The CSRC has also made it clear that it does not see theSecond Board simply as a "small SME Board" and attaches great importance to the companies' innovativeness and growth potential. Ultimately, whether or not such risks can be mitigated will depend on whether the quality of the companies that list on the Second Board improves and disclosure requirements are strictly complied with. For example, according to the rules governing Prospectuses of ChiNext Companies, companies are required to disclose the above-mentioned supplementary agreements as a control right risk. The point is whether such requirements will be complied with.Since there is a potentially large number of high-tech companies in China in the long term, whether or not the Second Board becomes one of the world's few successful venture capital markets will depend on whether all these rules and regulations succeed in shaping its development and the way in which it is run.The authorities clearly want to avoid a situation where the Second Board attracts a large number of second-rate companies and becomes a vehicle for market abuse as it would then run the risk of becoming an illiquid market shunned by investors who have lost trust in it. Indeed, such has been the number of companies applying to list on the Second Board that some observers have expressed concern about their quality.There has also been some concern about investor protection. For example, supplementary agreements between private equity funds and issuers pose a risk to retail investors in that they may suddenly be faced with a change in the controlling shareholder. This is because such agreements can result in a transfer of shares from the founder or controlling shareholder to a private equity fund if the company fails to meet certain agreed targets or in a shareholding structure that is different from the apparent one, for example. The problem of low liquidity, which has long faced the new Third Board market, where small-cap high-tech stocks are also traded, also needs to be addressed.Meanwhile, the Second Board's Public Offering Review Committee was officially established on 14 August. It has 35 members. A breakdown reveals that the number of representatives of the CSRC and the Shenzhen Stock Exchange has been limited to three and two, respectively, to ensure that the committee has the necessary number of technology specialists. Of the remainder, 14 are accountants, six lawyers,three from the Ministry of Science and Technology, three from the China Academy of Sciences, two from investment trust companies, one from an asset evaluation agency, and one from the National Development and Reform Commission (NDRC). It has been reported that the members include specialists in the six industry fields the CSRC considers particularly important for Second Board companies (namely, new energy, new materials, biotechnology and pharmaceuticals, energy conservation and environmental protection, services and IT).Source: Takeshi Jingu.2009.“China's Second Board”. Nomura Journal of Capital Markets Winter 2009 V ol.1 No.4.pp.1-15.二、翻译文章译文:中国创业板市场一、建立创业板市场及其意义2009年3月31日中国证券监督管理委员会(以下简称“中国证监会”)发行《中国证监会管理暂行办法》,首次在创业板市场上[即,第二个板,也叫创业板市场](“暂行办法”) 公开募股,从 2009年的5月1日开始生效,这标志着深圳证券交易所市场这个人们期待已久的合资企业即将诞生。
外文翻译原文

DOI10.1007/s10711-012-9699-zORIGINAL PAPERParking garages with optimal dynamicsMeital Cohen·Barak WeissReceived:19January2011/Accepted:22January2012©Springer Science+Business Media B.V.2012Abstract We construct generalized polygons(‘parking garages’)in which the billiard flow satisfies the Veech dichotomy,although the associated translation surface obtained from the Zemlyakov–Katok unfolding is not a lattice surface.We also explain the difficulties in constructing a genuine polygon with these properties.Keywords Active vitamin D·Parathyroid hormone-related peptide·Translation surfaces·Parking garages·Veech dichotomy·BilliardsMathematics Subject Classification(2000)37E351Introduction and statement of resultsA parking garage is an immersion h:N→R2,where N is a two dimensional compact connected manifold with boundary,and h(∂N)is afinite union of linear segments.A parking garage is called rational if the group generated by the linear parts of the reflections in the boundary segments isfinite.If h is actually an embedding,the parking garage is a polygon; thus polygons form a subset of parking garages,and rationals polygons(i.e.polygons all of whose angles are rational multiples ofπ)form a subset of rational parking garages.The dynamics of the billiardflow in a rational polygon has been intensively studied for over a century;see[7]for an early example,and[5,10,13,16]for recent surveys.The defi-nition of the billiardflow on a polygon readily extends to a parking garage:on the interior of N the billiardflow is the geodesicflow on the unit tangent bundle of N(with respect to the pullback of the Euclidean metric)and at the boundary,theflow is defined by elastic reflection (angle of incidence equals the angle of return).Theflow is undefined at thefinitely many M.Cohen·B.Weiss(B)Ben Gurion University,84105Be’er Sheva,Israele-mail:barakw@math.bgu.ac.ilM.Cohene-mail:comei@bgu.ac.ilpoints of N which map to‘corners’,i.e.endpoints of boundary segments,and hence at thecountable union of codimension1submanifolds corresponding to points in the unit tangentbundle for which the corresponding geodesics eventually arrive at corners in positive or neg-ative time.Since the direction of motion of a trajectory changes at a boundary segment viaa reflection in its side,for rational parking garages,onlyfinitely many directions of motionare assumed.In other words,the phase space of the billiardflow decomposes into invarianttwo-dimensional subsets corresponding tofixing the directions of motion.Veech[12]discovered that the billiardflow in some special polygons exhibits a strikingly he found polygons for which,in any initial direction,theflow is eithercompletely periodic(all orbits are periodic),or uniquely ergodic(all orbits are equidistrib-uted).Following McMullen we will say that a polygon with these properties has optimaldynamics.We briefly summarize Veech’s strategy of proof.A standard unfolding construc-tion usually attributed to Zemlyakov and Katok[15]1,associates to any rational polygon Pa translation surface M P,such that the billiardflow on P is essentially equivalent to thestraightlineflow on M P.Associated with any translation surface M is a Fuchsian group M,now known as the Veech group of M,which is typically trivial.Veech found M and P forwhich this group is a non-arithmetic lattice in SL2(R).We will call these lattice surfaces and lattice polygons respectively.Veech investigated the SL2(R)-action on the moduli space of translation surfaces,and building on earlier work of Masur,showed that lattice surfaces haveoptimal dynamics.From this it follows that lattice polygons have optimal dynamics.This chain of reasoning remains valid if one starts with a parking garage instead of apolygon;namely,the unfolding construction associates a translation surface to a parkinggarage,and one may define a lattice parking garage in an analogous way.The arguments ofVeech then show that the billiardflow in a lattice parking garage has optimal dynamics.Thisgeneralization is not vacuous:lattice parking garages,which are not polygons,were recentlydiscovered by Bouw and Möller[2].The term‘parking garage’was coined by Möller.A natural question is whether Veech’s result admits a converse,i.e.whether non-latticepolygons or parking garages may also have optimal dynamics.In[11],Smillie and the sec-ond-named author showed that there are non-lattice translation surfaces which have optimaldynamics.However translation surfaces arising from billiards form a set of measure zero inthe moduli space of translation surfaces,and it was not clear whether the examples of[11]arise from polygons or parking garages.In this paper we show:Theorem1.1There are non-lattice parking garages with optimal dynamics.An example of such a parking garage is shown in Fig.1.Veech’s work shows that for lattice polygons,the directions in which all orbits are periodicare precisely those containing a saddle connection,i.e.a billiard path connecting corners ofthe polygon which unfold to singularities of the corresponding surface.Following Cheunget al.[3],if a polygon P has optimal dynamics,and the periodic directions coincide with thedirections of saddle connections,we will say that P satisfies strict ergodicity and topologicaldichotomy.It is not clear to us whether our example satisfies this stronger property.As weexplain in Remark3.2below,this would follow if it were known that the center of the regularn-gon is a‘connection point’in the sense of Gutkin,Hubert and Schmidt[8]for some nwhich is an odd multiple of3.Veech also showed that for a lattice polygon P,the number N P(T)of periodic strips on P of length at most T satisfies a quadratic growth estimate of the form N P(T)∼cT2for a positive constant c.As we explain in Remark3.3,our examples also satisfy such a quadratic growth estimate.1But dating back at least to Fox and Kershner[7].Fig.1A non-lattice parkinggarage with optimal dynamics.(Here 2/n represents angle 2π/n )It remains an open question whether there is a genuine polygon which has optimal dynam-ics and is not a lattice polygon.Although our results make it seem likely that such a polygon exists,in her M.Sc.thesis [4],the first-named author obtained severe restrictions on such a polygon.In particular she showed that there are no such polygons which may be constructed from any of the currently known lattice examples via the covering construction as in [11,13].We explain these results and prove a representative special case in §4.2PreliminariesIn this section we cite some results which we will need,and deduce simple consequences.For the sake of brevity we will refer the reader to [10,11,16]for definitions of translation surfaces.Suppose S 1,S 2are compact orientable surfaces and π:S 2→S 1is a branched cover.That is,πis continuous and surjective,and there is a finite 1⊂S 1,called the set of branch points ,such that for 2=π−1( 1),the restriction of πto S 2 2is a covering map of finite degree d ,and for any p ∈ 1,#π−1(p )<d .A ramification point is a point q ∈ 2for which there is a neighborhood U such that {q }=U ∩π−1(π(q ))and for all u ∈U {q },# U ∩π−1(π(u )) ≥2.If M 1,M 2are translation surfaces,a translation map is a surjective map M 2→M 1which is a translation in charts.It is a branched cover.In contrast to other authors (cf.[8,13]),we do not require that the set of branch points be distinct from the singularities of M 1,or that they be marked.It is clear that the ramification points of the cover are singularities on M 2.If M is a lattice surface,a point p ∈M is called periodic if its orbit under the group of affine automorphisms of M is finite.A point p ∈M is called a connection point if any seg-ment joining a singularity with p is contained in a saddle connection (i.e.a segment joining singularities)on M .The following proposition summarizes results discussed in [7,9–11]:Proposition 2.1(a)A non-minimal direction on a translation surface contains a saddle connection.(b)If M 1is a lattice surface,M 2→M 1is translation map with a unique branch point,then any minimal direction on M 2is uniquely ergodic.(c)If M2→M1is a translation map such that M1is a lattice surface,then all branchpoints are periodic if and only if M2is a lattice surface.(d)If M2→M1is a translation map with a unique branch point,such that M1is a latticesurface and the branch point is a connection point,then any saddle connection direction on M2is periodic.Corollary2.2Let M2→M1be a translation map such that M1is a lattice surface with a unique branch point p.Then:(1)M2has optimal dynamics.(2)If p is a connection point then M2satisfies topological dichotomy and strict ergodicity.(3)If p is not a periodic point then M2is not a lattice surface.Proof To prove(1),by(b),the minimal directions are uniquely ergodic,and we need to prove that the remaining directions are either completely periodic or uniquely ergodic. By(a),in any non-minimal direction on M2there is a saddle connectionδ,and there are three possibilities:(i)δprojects to a saddle connection on M1.(ii)δprojects to a geodesic segment connecting the branch point p to itself.(iii)δprojects to a geodesic segment connecting p to a singularity.In case(i)and(ii)since M1is a lattice surface,the direction is periodic on M1,hence on M2as well.In case(iii),there are two subcases:ifδprojects to a part of a saddle connec-tion on M1,then it is also a periodic direction.Otherwise,in light of Proposition2.1(a),the direction must be minimal in M1,and hence,by Proposition2.1(b),uniquely ergodic in M2. This proves(1).Note also that if p is a connection point then the last subcase does not arise, so all directions which are non-minimal on M2are periodic.This proves(2).Statement(3) follows from(c).We now describe the unfolding construction[7,15],extended to parking garages.Let P=(h:N→R2).An edge of P is a connected subset L of∂N such that h(L)is a straight segment and L is maximal with these properties(with respect to inclusion).A vertex of P is any point which is an endpoint of an edge.The angle at a vertex is the total interior angle, measured via the pullback of the Euclidean metric,at the vertex.By convention we always choose the positive angles.Note that for polygons,angles are less than2π,but for parking garages there is no apriori upper bound on the angle at a vertex.Since our parking garages are rational,all angles are rational multiples ofπ,and we always write them as p/q,omitting πfrom the notation.Let G P be the dihedral group generated by the linear parts of reflections in h(L),for all edges L.For the sake of brevity,if there is a reflection with linear part gfixing a line parallel to L,we will say that gfixes L.Let S be the topological space obtained from N×G P by identifying(x,g1)with(x,g2)whenever g−11g2fixes an edge containing h(x).Topologically S is a compact orientable surface,and the immersions g◦h on each N×{g}induce an atlas of charts to R2which endows S with a translation surface structure.We denote this translation surface by M P,and writeπP for the map N×G P→M P.We will be interested in a‘partial unfolding’which is a variant of this construction,in which we reflect a parking garage repeatedly around several of its edges to form a larger parking garage.Formally,suppose P=(h:N→R2)and Q=(h :N →R2)are parking garages.For ≥1,we say that P tiles Q by reflections,and that is the number of tiles,if the following holds.There are maps h 1,...h :N→N and g1,...,g ∈G P(not necessarily distinct)satisfying:(A)The h i are homeomorphisms onto their images,and N = h i (N ).(B)For each i ,the linear part of h ◦h i ◦h −1is everywhere equal to g i .(C)For each 1≤i <j ≤ ,let L i j =h i (N )∩h j (N )and L =(h i )−1(L i j ).Then (h j )−1◦h i is the identity on L ,and L is either empty,or a vertex,or an edge of P .If L is an edge then h i (N )∪h j (N )is a neighborhood of L i j.If L i j is a vertex then there is a finite set of i =i 1,i 2,...,i k =j such that h i s (N )contains a neighborhood of L i j ,and each consecutive pair h i t (N ),h i t +1(N )intersect along an edge containing L i j .V orobets [13]realized that a tiling of parking garages gives rise to a branched cover.More precisely:Proposition 2.3Suppose P tiles Q by reflections with tiles,M P ,M Q are the correspond-ing translation surfaces obtained via the unfolding construction,and G P ,G Q are the cor-responding reflection groups.Then there is a translation map M Q →M P ,such that the following hold:(1)G Q ⊂G P .(2)The branch points are contained in the G P -orbit of the vertices of P .(3)The degree of the cover is [G P :G Q ].(4)Let z ∈M P be a point which is represented (as an element of N ×{1,...,r })by(x ,k )with x a vertex in P with angle m n (where gcd (m ,n )=1).Let (y i )⊂M Q be the pre-images of z,with angles k i m n in Q .Then z is a branch point of the cover if and only if k i n for some i.Proof Assertion (1)follows from the fact that Q is tiled by P .Since this will be impor-tant in the sequel,we will describe the covering map M Q →M P in detail.We will map (x ,g )∈N ×G Q to πP (x ,gg i )∈M P ,where x =h i (x ).We now check that this map is independent of the choice of x ,i ,and descends to a well-defined map M Q →M P ,which is a translation in charts.If x =h i (x 1)=h j (x 2)then x 1=x 2since (h i )−1◦h j is the identity.If x is in the relative interior of an edge L i j thenπP (x ,gg i )=πP (x ,gg j )(1)since (gg i )−1gg j =g −1i g j fixes an edge containing h (x 1).If x 1is a vertex of P then one proves (1)by an induction on k ,where k is as in (C).This shows that the map is well-defined.We now show that it descends to a map M Q →M P .Suppose (x ,g ),(x ,g )are two points in N ×G Q which are identified in M Q ,i.e.x ∈∂N is in the relative interior of an edge fixed by g −1g .By (C)there is a unique i such that x is in the image of h i .Thus (x ,g )maps to (x ,gg i )and (x ,g )maps to (x ,g g i ),and g −1i g −1g g i fixes the edge through x =g −1i (x ).It remains to show that the map we have defined is a translation in charts.This follows immediately from the chain rule and (B).Assertion (2)is simple and left to the reader.For assertion (3)we note that M P (resp.M Q )is made of |G P |(resp. |G Q |)copies of P .The point z will be a branch point if and only if the total angle around z ∈M P differs from the total angle around one of the pre-images y i ∈M Q .The total angle at a singularity corresponding to a vertex with angle r /s (where gcd (r ,s )=1)is 2r π,thus the total angle at z is 2m πand the total angle at y i is 2k i m πgcd (k i ,n ).Assertion (4)follows.3Non-lattice dynamically optimal parking garagesIn this section we prove the following result,which immediately implies Theorem1.1: Theorem3.1Let n≥9be an odd number divisible by3,and let P be an isosceles triangle with equal angles1/n.Let Q be the parking garage made of four copies of P glued as in Fig.1, so that Q has vertices(in cyclic order)with angles1/n,2/n,3/n,(n−2)/n,2/n,3(n−2)/n. Then M P is a lattice surface and M Q→M P is a translation map with one aperiodic branchpoint.In particular Q is a non-lattice parking garage with optimal dynamics.Proof The translation surface M P is the double n-gon,one of Veech’s original examples of lattice surfaces[12].The groups G P and G Q are both equal to the dihedral group D n.Thus by Proposition2.3,the degree of the cover M Q→M P is four.Again by Proposition2.3, since n is odd and divisible by3,the only vertices which correspond to branch points are the two vertices z1,z2with angle2/n(they correspond to the case k i=2while the other vertices correspond to1or3).In the surface M P there are two points which correspond to vertices of equal angle in P(the centers of the two n-gons),and these points are known to be aperiodic [9].We need to check that z1and z2both map to the same point in M P.This follows from the fact that both are opposite the vertex z3with angle3/n,which also corresponds to the center of an n-gon,so in M P project to a point which is distinct from z3. Remark3.2As of this writing,it is not known whether the center of the regular n-gon is a connection point on the double n-gon surface.If this turns out to be the case for some n which is an odd multiple of3,then by Corollary2.2(2),our construction satisfies strict ergodicity and topological dichotomy.See[1]for some recent related results.Remark3.3Since our examples are obtained by taking branched covers over lattice surfaces, a theorem of Eskin et al.[6,Thm.8.12]shows that our examples also satisfy a quadratic growth estimate of the form N P(T)∼cT2;moreover§9of[6]explains how one may explicitly compute the constant c.4Non-lattice optimal polygons are hard tofindIn this section we present results indicating that the above considerations will not easily yield a non-lattice polygon with optimal dynamics.Isolating the properties necessary for our proof of Theorem3.1,we say that a pair of polygons(P,Q)is suitable if the following hold:•P is a lattice polygon.•P tiles Q by reflections.•The corresponding cover M Q→M P as in Proposition2.3has a unique branch point which is aperiodic.In her M.Sc.thesis at Ben Gurion University,thefirst-named author conducted an exten-sive search for a suitable pair of polygons.By Corollary2.2,such a pair will have yielded a non-lattice polygon with optimal dynamics.The search begins with a list of candidates for P,i.e.a list of currently known lattice polygons.At present,due to work of many authors, there is a fairly large list of known lattice polygons but there is no classification of all lattice polygons.In[4],the full list of lattice polygons known as of this writing is given,and the following is proved:Theorem4.1(M.Cohen)Among the list of lattice surfaces given in[4],there is no P for which there is Q such that(P,Q)is a suitable pair.The proof of Theorem4.1contains a detailed case-by-case analysis for each of the differ-ent possible P.These cases involve some common arguments which we will illustrate in this section,by proving the special case in which P is any of the obtuse triangles investigated byWard[14]:Theorem4.2For n≥4,let P=P n be the(lattice)triangle with angles1n,12n,2n−32n.Then there is no polygon Q for which(P,Q)is a suitable pair.Our proof relies on some auxiliary statements which are of independent interest.In all of them,M Q→M P is the branched cover with unique branch point corresponding to a suitable pair(P,Q).These statements are also valid in the more general case in which P,Q are parking garages.Recall that an affine automorphism of a translation surface is a homeomorphism which is linear in charts.We denote by Aff(M)the group of affine automorphisms of M and by D:Aff(M)→GL2(R)the homomorphism mapping an affine automorphism to its linear part.Note that we allow orientation-reversing affine automorphisms,i.e.detϕmay be1 or−1.We now explain how G P acts on M P by translation equivalence.LetπP:N×G P→M P and S be as in the discussion preceding Proposition2.3,and let g∈G P.Since the left action of g on G is a permutation and preserves the gluing ruleπP,the map N×G P→N×G P sending(x,g )to(x,g−1g )induces a homeomorphismϕ:S→S and g◦h◦ϕis a translation in charts.Thus g∈G P gives a translation isomorphism of M P,and similarly g∈G P gives a translation isomorphism of M Q.Lemma4.3The branch point of the cover p:M Q→M P isfixed by G Q.Proof Since G Q⊂G P,any g∈G Q induces translation isomorphisms of both M P and M Q.We denote both by g.The definition of p given in thefirst paragraph of the proof of Proposition2.3shows that p◦g=g◦p;namely both maps are induced by sending (x ,g )∈N ×G Q toπP(x,gg g i),where x =h i(x).Since the cover p has a unique branch point,any g∈G Q mustfix it. Lemma4.4If an affine automorphismϕof a translation surface has infinitely manyfixed points then Dϕfixes a nonzero vector,in its linear action on R2.Proof Suppose by contradiction that the linear action of Dϕon the plane has zero as a uniquefixed point,and let Fϕbe the set offixed points forϕ.For any x∈Fϕwhich is not a singularity,there is a chart from a neighborhood U x of x to R2with x→0,and a smaller neighborhood V x⊂U x,such thatϕ(V x)⊂U x and when expressed in this chart,ϕ|V x is given by the linear action of Dϕon the plane.In particular x is the onlyfixed point in V x. Similarly,if x∈Fϕis a singularity,then there is a neighborhood U x of x which maps to R2 via afinite branched cover ramified at x→0,such that the action ofϕin V x⊂U x covers the linear action of Dϕ.Again we see that x is the onlyfixed point in V x.By compactness wefind that Fϕisfinite,contrary to hypothesis. Lemma4.5Suppose M is a lattice surface andϕ∈Aff(M)has Dϕ=−Id.Then afixed point forϕis periodic.Proof LetF1={σ∈Aff(M):Dσ=−Id}.Thenϕ∈F1and F1isfinite,since it is a coset for the group ker D which is known to be finite.Let A⊂M be the set of points which arefixed by someσ∈F1.By Lemma4.4this is afinite set,which contains thefixed points forϕ.Thus in order to prove the Lemma,it suffices to show that A is Aff(M)-invariant.Letψ∈Aff(M),and let x∈A,so that x=σ(x)with Dσ=−Id.Since-Id is central in GL2(R),D(σψ)=D(ψσ),so there is f∈ker D such thatψσ=fσψ.Thereforeψ(x)=ψσ(x)=fσψ(x),and fσ∈F1.This proves thatψ(x)∈A.Remark4.6This improves Theorem10of[8],where a similar conclusion is obtained under the additional assumptions that M is hyperelliptic and Aff(M)is generated by elliptic ele-ments.The following are immediate consequences:Corollary4.7Suppose(P,Q)is a suitable pair.Then•−Id/∈D(G Q).•None of the angles between two edges of Q are of the form p/q with gcd(p,q)=1and q even.Proof of Theorem4.2We will suppose that Q is such that(P,Q)are a suitable pair and reach a contradiction.If n is even,then Aff(M P)contains a rotation byπwhichfixes the points in M P coming from vertices of P.Thus by Lemma4.5all vertices of P give rise to periodic points,contradicting Proposition2.1(c).So n must be odd.Let x1,x2,x3be the vertices of P with corresponding angles1/n,1/2n,(2n−3)/2n. Then x3gives rise to a singularity,hence a periodic point.Also using Lemma4.5and the rotation byπ,one sees that x2also gives rise to a periodic point.So the unique branch point must correspond to the vertex x1.The images of the vertex x1in P give rise to two regular points in M P,marked c1,c2in Fig.2.Any element of G P acts on{c1,c2}by a permutation, so by Lemma4.3,G Q must be contained in the subgroup of index twofixing both of the c i. Let e1be the edge of P opposite x1.Since the reflection in e1,or any edge which is an image of e1under G P,swaps the c i,we have:e1is not a boundary edge of Q.(2) We now claim that in Q,any vertex which corresponds to the vertex x3from P is alwaysdoubled,i.e.consists of an angle of(2n−3)/n.Indeed,for any polygon P0,the group G P0 is the dihedral group D N where N is the least common multiple of the denominators of theangles at vertices of P0.In particular it contains-Id when N is even.Writing(2n−3)/2n in reduced form we have an even denominator,and since,by Corollary4.7,−Id/∈G Q,in Q the angle at vertex x3must be multiplied by an even integer2k.Since2k(2n−3)/2n is bigger than2if k>1,and since the total angle at a vertex of a polygon is less than2π,we must have k=1,i.e.any vertex in Q corresponding to the vertex x3is always doubled.This establishes the claim.It is here that we have used the assumption that Q is a polygon and not a parking garage.Fig.2Ward’s surface,n=5Fig.3Two options to start the construction ofQThere are two possible configurations in which a vertex x3is doubled,as shown in Fig.3. The bold lines indicate lines which are external,i.e.boundary edges of Q.By(2),the con-figuration on the right cannot occur.Let us denote the polygon on the left hand side of Fig.3by Q0.It cannot be equal to Q,since it is a lattice polygon.We now enlarge Q0by adding copies of P step by step,as described in Fig.4.Without loss of generality wefirst add triangle number1.By(2),the broken line indicates a side which must be internal in Q.Therefore,we add triangle number 2.We denote the resulting polygon by Q1.One can check by computing angles,using thefact that n is odd,and using Proposition2.3(4)that the cover M Q1→M P will branch overthe points a corresponding to vertex x2.Since the allowed branching is only over the points corresponding to x1,we must have Q1 Q,so we continue the construction.Without loss of generality we add triangle number3.Again,by(2),the broken line indicates a side which must be internal in Q.Therefore,we add triangle number4,obtaining Q2.Now,using Prop-osition2.3(4)again,in the cover M Q2→M P we have branching over two vertices u andv which are both of type x1and correspond to distinct points c1and c2in M P.This implies Q2 Q.Fig.4Steps of the construction of QSince both vertices u and v are delimited by2external sides,we cannot change the angle to prevent the branching over one of these points.This means that no matter how we continue to construct Q,the branching in the cover M Q→M P will occur over at least two points—a contradiction.Acknowledgments We are grateful to Yitwah Cheung and Patrick Hooper for helpful discussions,and to the referee for a careful reading and helpful remarks which improved the presentation.This research was supported by the Israel Science Foundation and the Binational Science Foundation.References1.Arnoux,P.,Schmidt,T.:Veech surfaces with non-periodic directions in the tracefield.J.Mod.Dyn.3(4),611–629(2009)2.Bouw,I.,Möller,M.:Teichmüller curves,triangle groups,and Lyapunov exponents.Ann.Math.172,139–185(2010)3.Cheung,Y.,Hubert,P.,Masur,H.:Topological dichotomy and strict ergodicity for translation surfaces.Ergod.Theory Dyn.Syst.28,1729–1748(2008)4.Cohen,M.:Looking for a Billiard Table which is not a Lattice Polygon but satisfies the Veech dichotomy,M.Sc.thesis,Ben-Gurion University(2010)/pdf/1011.32175.DeMarco,L.:The conformal geometry of billiards.Bull.AMS48(1),33–52(2011)6.Eskin,A.,Marklof,J.,Morris,D.:Unipotentflows on the space of branched covers of Veech surfaces.Ergod.Theorm Dyn.Syst.26(1),129–162(2006)7.Fox,R.H.,Kershner,R.B.:Concerning the transitive properties of geodesics on a rational polyhe-dron.Duke Math.J.2(1),147–150(1936)8.Gutkin,E.,Hubert,P.,Schmidt,T.:Affine diffeomorphisms of translation surfaces:Periodic points,Fuchsian groups,and arithmeticity.Ann.Sci.École Norm.Sup.(4)36,847–866(2003)9.Hubert,P.,Schmidt,T.:Infinitely generated Veech groups.Duke Math.J.123(1),49–69(2004)10.Masur,H.,Tabachnikov,S.:Rational billiards andflat structures.In:Handbook of dynamical systems,vol.1A,pp.1015–1089.North-Holland,Amsterdam(2002)11.Smillie,J.,Weiss,B.:Veech dichotomy and the lattice property.Ergod.Theorm.Dyn.Syst.28,1959–1972(2008)Geom Dedicata12.Veech,W.A.:Teichmüller curves in moduli space,Eisenstein series and an application to triangularbilliards.Invent.Math.97,553–583(1989)13.V orobets,Y.:Planar structures and billiards in rational polygons:the Veech alternative.(Russian);trans-lation in Russian Math.Surveys51(5),779–817(1996)14.Ward,C.C.:Calculation of Fuchsian groups associated to billiards in a rational triangle.Ergod.TheoryDyn.Syst.18,1019–1042(1998)15.Zemlyakov,A.,Katok,A.:Topological transitivity of billiards in polygons,Math.Notes USSR Acad.Sci:18:2291–300(1975).(English translation in Math.Notes18:2760–764)16.Zorich,A.:Flat surfaces.In:Cartier,P.,Julia,B.,Moussa,P.,Vanhove,P.(eds.)Frontiers in numbertheory,physics and geometry,Springer,Berlin(2006)123。
- 1、下载文档前请自行甄别文档内容的完整性,平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益,请联系客服反馈,我们会尽快为您处理(人工客服工作时间:9:00-18:30)。
Reforming Agricultural Trade: Not Just for the Wealthy CountriesIn the early 1990s, Mozambique removed a ban on raw cashew exports, which was originally imposed to guarantee a source of raw nuts to its local processing industry and to prevent a drop in exports of processed nuts. As a result, a million cashew farmers received higher prices for the nuts in the domestic market. But, at least half the higher prices received for exports of these nuts went to traders, and not to farmers, so there was no increase in production in response to the higher prices. At the same time, Mozambique’s nut-processing industry lost its guaranteed supply of raw nuts, and was forced to shut down processing plants and lay off 7,000 workers (FAO 2003).In Zambia, before liberalization, maize producers benefited from subsidies to the mining sector, which lowered the price of fertilizer. A State buyer further subsidized small farmers. When these subsidies were removed, and the para-State privatized, larger farmers close to international markets saw few changes, but small farmers in remote areas were left without a formal market for their maize.In Vietnam, trade liberalization was accompanied by tax reductions, land reforms, and marketing reforms that allowed farmers to benefit from increased sales to the market. As Vietnam made these investments, it began to phase out domestic subsidies and reduce border protection against imports. An aggressive program of targeted rural investments accompanied these reforms. During this liberalization, Vietnam’s overall economy grew at 7% annually, agricultural output grew by 6%, and the proportion of undernourished people fell from 27% to 19% of the population. Vietnam moved from being a net importer of food to a net exporter (FAO 2003).Similarly, in Zimbabwe, before liberalization of the cotton sector, the government was the single buyer of cotton from farmers, offering low prices to subsidized textile firms. Facing lower prices, commercial farmers diversified into other crops (tobacco, horticulture) but smaller farmers who could not diversify suffered. Internal liberalization eliminated price controls and privatized the marketing board. The result was higher cotton prices and competition among the three principal buyers. Poorer farmers benefited through increased market opportunities, as well as better extension and services. As a result, agricultural employment rose by 40%, with production of traditional and non-traditional crops increasing.Policy reforms can decrease employment in the short run, but in general, changes in employment caused by trade liberalization are small relative to the overall size of the economy and the natural dynamics of the labor market. But, for some countries that rely heavily on one sector and do not have flexible economies, the transition can be difficult. Even though there are long-term and economy-wide benefits to trade liberalization, there may be short-term disruptions and economic shocks which may be hard for the poor to endure.Once a government decides to undertake a reform, the focus should be on easing the impact of reforms on the losers –either through education, retraining, or income assistance. Government policy should also focus on helping those who will be able to compete in the new environment to take advantage of new opportunities. Even though trade on balance has a positive impact on growth, and therefore on poverty alleviation, developing countries should pursue trade liberalization with a pro-poor strategy. In other words, they should focus on liberalizing those sectors that will absorb non-skilled labor from rural areas, as agriculture becomes more competitive. The focus should be on trade liberalization that will enhanceeconomic sectors that have the potential to employ people in deprived areas. Trade liberalization must be complemented by policies to improve education, rural roads, communications, etc., so that liberalization can be positive for people living in rural areas, not just in urban centers or favored areas. These underlying issues need to be addressed if trade (or any growth) is to reach the poorest; or the reforms and liberalization need to be directed toward smallholders, and landless and unskilled labor.BUT THE POOR IN D EVELOPING COUNTRIES DON’T BENEFIT EQUALLY All policies create winners and losers. Continuing the status quo simply maintains the current cast of winners and losers. Too often in developing countries, the winners from current policies are not the poor living in rural areas. Policy reforms (whether in trade or in other areas) simply create a different set of winners and losers.Notwithstanding the overall positive analyses of the impact of trade liberalization on developing countries as a group, there are significant variations by country, commodity, and different sectors within developing countries. Most analysts combine all but the largest developing countries into regional groupings, so it is difficult to determine the precise impacts on individual countries. Even those studies that show long-term or eventual gains for rural households or for the poor do not focus on the costs imposed during the transition from one regime to another. It is even more difficult to evaluate the impact on different types of producers within different countries, such as smallholders and subsistence farmers. Also, economic models cannot evaluate how trade policies will affect poverty among different households, or among women and children within households.Allen Winters (2002) has proposed a useful set of questions that policy-makers should ask when they consider trade reforms:1. Will the effects of changed border prices be passed through the economy? If not, the effects –positive or negative – on poverty will be muted.2. Is reform likely to destroy or create markets? Will it allow poor consumers to obtain new goods?3. Are reforms likely to affect different household members – women, children – differently?4. Will spillovers be concentrated on areas/activities that are relevant to the poor?5. What factors – land, labor, and capital – are used in what sectors? How responsive is the supply of those factors to changes in prices?6. Will reform reduce or increase government revenue? By how much?7. Will reforms allow people to combine their domestic and international activities, or will it require them to switch from one to another?8. Does the reform depend on or affect the ability of poor people to assume risks?9. Will reforms cause major shocks for certain regions within the country?10. Will transitional unemployment be concentrated among the poor?Although trade liberalization is often blamed for increasing poverty in developing countries, the links between trade liberalization and poverty are more complex. Clearly, more open trade regimes lead to higher rates of economic growth, and without economic growth any effort to alleviate poverty, hunger, and malnutrition will be unproductive. But, without accompanying national policies in education, health, land reforms, micro-credit, infrastructure, and governance, economic growth (whether derived from trade or other sources) is much less likely to alleviate poverty, hunger, and malnutrition in the poorest developing countries.CONCLUSIONSThe imperative to dismantle unjust structures and to halt injurious actions is enshrined in the Millennium Development Goals, and in the goals of the Doha Development Round. This imperative has been primarily directed at the OECD countries that maintain high levels of agricultural subsidies and protection against many commodities that are vital to the economic well-being of developing countries. The OECD countries must reduce their trade barriers, reduce and reform their domestic subsidies; but, as this chapter makes clear, the OECD reforms must be accompanied by trade policy reforms in the developing countries as well.Open trade is one of the strongest forces for economic development and growth. Developing countries and civil society groups who oppose these trade reforms i n order to ‘protect’ subsistence farmers are doing these farmers a disservice. Developing countries and civil society are correct in the narrow view that markets cannot solve every problem, and that there is a role for government and for public policies. As the Doha negotiators get down to business, their energies would be better used in ensuring that developing countries begin to prepare for a more open trade regime by enacting policies that promote overall economic growth and that promote agricultural development. Their energies would be better spent convincing the population (taxpayers and consumers) in developed countries of the need for agricultural trade reform, and in convincing the multilateral aid agencies to help developing countries invest in public goods and public policies to ensure that trade policy reforms are pro-poor.It is clear from an examination of the evidence that trade reform, by itself, does not exacerbate poverty in developing countries. Rather, the failure of trade reforms to alleviate poverty lies in the underlying economic structures, adverse domestic policies, and the lack of strong flanking measures. To ensure that trade reform is pro-poor, the key is not to seek additional exemptions from trade disciplines for developing countries, which will only be met with counter-demands for other exemptions by developed countries, but to ensure that the WTO agreement is strong and effective in disciplining subsidies and reducing barriers to trade by all countries.Open trade is a key determinant of economic growth, and economic growth is the only path to poverty alleviation. This is equally true in agriculture as in other sectors of the economy. In most cases, trade reforms in agriculture will benefit the poor in developing countries. In cases where the impact of trade reforms is ambiguous or negative, the answer is not to postpone trade reform. Rather, trade reforms must be accompanied by flanking policies that make needed investments or that provide needed compensation, so that trade-led growth can benefit the poor.。