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外文参考文献翻译-中文

外文参考文献翻译-中文

外⽂参考⽂献翻译-中⽂基于4G LTE技术的⾼速铁路移动通信系统KS Solanki教授,Kratika ChouhanUjjain⼯程学院,印度Madhya Pradesh的Ujjain摘要:随着时间发展,⾼速铁路(HSR)要求可靠的,安全的列车运⾏和乘客通信。

为了实现这个⽬标,HSR的系统需要更⾼的带宽和更短的响应时间,⽽且HSR的旧技术需要进⾏发展,开发新技术,改进现有的架构和控制成本。

为了满⾜这⼀要求,HSR采⽤了GSM的演进GSM-R技术,但它并不能满⾜客户的需求。

因此采⽤了新技术LTE-R,它提供了更⾼的带宽,并且在⾼速下提供了更⾼的客户满意度。

本⽂介绍了LTE-R,给出GSM-R与LTE-R之间的⽐较结果,并描述了在⾼速下哪种铁路移动通信系统更好。

关键词:⾼速铁路,LTE,GSM,通信和信令系统⼀介绍⾼速铁路需要提⾼对移动通信系统的要求。

随着这种改进,其⽹络架构和硬件设备必须适应⾼达500公⾥/⼩时的列车速度。

HSR还需要快速切换功能。

因此,为了解决这些问题,HSR 需要⼀种名为LTE-R的新技术,基于LTE-R的HSR提供⾼数据传输速率,更⾼带宽和低延迟。

LTE-R能够处理⽇益增长的业务量,确保乘客安全并提供实时多媒体信息。

随着列车速度的不断提⾼,可靠的宽带通信系统对于⾼铁移动通信⾄关重要。

HSR的应⽤服务质量(QOS)测量,包括如数据速率,误码率(BER)和传输延迟。

为了实现HSR的运营需求,需要⼀个能够与 LTE保持⼀致的能⼒的新系统,提供新的业务,但仍能够与GSM-R长时间共存。

HSR系统选择合适的⽆线通信系统时,需要考虑性能,服务,属性,频段和⼯业⽀持等问题。

4G LTE系统与第三代(3G)系统相⽐,它具有简单的扁平架构,⾼数据速率和低延迟。

在LTE的性能和成熟度⽔平上,LTE- railway(LTE-R)将可能成为下⼀代HSR通信系统。

⼆ LTE-R系统描述考虑LTE-R的频率和频谱使⽤,对为⾼速铁路(HSR)通信提供更⾼效的数据传输⾮常重要。

国际服务贸易外文文献翻译

国际服务贸易外文文献翻译

国际服务贸易外文翻译文献(含:英文原文及中文译文)文献出处:《World Development》,2015,12(1):35-44.英文原文The research of international service trade and economic growth theoryChakraborty Kavin1 IntroductionThe study of the relation between international trade and economic growth is one of the most active issues. Since 1980s, the world has been in transition from national economy orientating towards natural resources and manufacturing industry to global and regional economy orientating towards information resources and service industry. After the signature of GA TS in1994, the institutional arrangements on liberalizing service trade result in a world-wide involvement division and exchanges of service trade, and it is undoubtedly that the positive interaction between service trade and investment leads to economic growth. But the theoretical research on service trade lags behind practice.Is it a statistic phenomenon or a universal rule of economic growth? To approach the above two issues from theoretical and empirical perspective is of great value to policy-making.For the proposition of that "International service trade will drive economic growth". Theoretical analysis shows that although service tradeis not a direct interpretative variable to economic growth, it can effect economic growth indirectly through other growing factors and technology upgrade, but the ways and mechanisms are different in different stages. In a certain stage of economic development, service trade (including investment) will have static and dynamic effect on factors supply and technology upgrade in one county, which will lead to the domestic alteration of resources condition structure. It is the enterprises that select industry structure, technology structure and trade structure according to dynamic alteration way of comparative technology structure and trade structure, which will ultimately promote evolution of economic growth gradually. So far as operational mechanism of service trade and investment is concerned, service trade affects factors supply in one country by physical capital accumulating effect, human capital effect, technology upgrade effect, institutional transition effect, employment effect and externality of technology, then influences the upgrade of industrial structure, the upgrade of technological structure and the transition of mode of economic growth. It is obvious that dynamic effect is greater than static effect; that external effect is playing more important role than internal effect; and that technology spillover effect of foreign direct investment in service industry is greater than that of service trade in a narrow sense (including across-border supply, consumption abroad and movement of natural person).For the research of mechanism about how service trade drive economic growth. Firstly, the paper verifies the causality between service trade and economic growths concerning different economic bodies and the representative countries. The results show that there are causalities between international service trade and economic growth in the whole world, in the developed countries, in the US and in china. In the developing countries, service trade is the Granger cause of economic growth; In the whole world and the developing countries, economic growth is the Granger cause of service trade; In the US, service export is the Granger cause of economic growth, and economic growth is the Granger cause of service import. On this basis, it is concluded that the opening of service industry will benefit economic growth in one country. Secondly, in order to explore on how the service trade and investment act on economic growth, empirical studies are employed to explain the case of US and that of China. The results show that the routes by which service trade affects economic growth in the US can be rowed as follows from more significant to less: employment effect, human capital effect, physical capital effect, technology effect, institution effect. The results of empirical analysis of China can be summarized that: the routes by which service export affects economic growth can be rowed as follows: employment effect, physical capital effect, institution effect, human capital effect, technology effect; the routs by which service import affectseconomic growth can be rowed as follows: technology effect, institution effect, employment effect, human capital effect, physical capital effect; the routes by which FDI in service affects economic growth can be rowed as follows: technology effect, human capital effect, institution effect, employment effect, physical capital effect. Moreover, the effect of FDI in service is stronger than service import, and the effect of service import is stronger than service export.According to the empirical test in this paper, the conclusion can be drawn as follows: service trade in a narrow sense will have static and dynamic effects on factor supply in one country through import and export of service, FDI in service industry is one of the most important cross-border transactions and is another important channel which will affect the transition of advantages on factor supply in one country. It should be emphasized that the above-mentioned channels will have different effects on countries at different stages of economic development. Whether the roles can be brought into play or not depends on given restraints. The input output of factors themselves cannot form a clear function, but will interact together and act on economic growth hand in hand through numerous feedback chain.Chinese economy is now undergoing transformation from elementary age to middle age of industrialization. Service trade and investment in current period have both advantages and disadvantages.Based on these judgments, we propose that China should pursue a policy favoring protectionism on management of service trade and adopt relevant countermeasures as follows. Scientific development view should be formed with an eye to harmonizing development of three industries so as to lay a solid industries foundation for service trade; The strategic programming should be stipulated and the market of service trade should be opened gradually; The rule of international transfer of service trade should be mastered and environment of utilizing foreign investment on service industry should be improved.As the characteristics of the world's service-oriented economy have gradually emerged, service trade originating from the upgrading of industrial structure has developed rapidly, and the scale of service trade is rapidly expanding. From the statistical data, the total exports of world service trade rose rapidly from 365 billion U.S. dollars in 1980 to 377.779 billion U.S. dollars in 2008, an increase of 9.35 times. Compared with the trade of goods with a long history, service trade is a new form of trade. With the continuous increase in absolute size and relatively low levels, service trade has become a focus of attention in modern society.2 The impact of overall service trade on economic growthAccording to the WTO General Agreement on Trade in Services (GA TS), which was signed in 1994, trade in services includes Cross- border Supply, Consumption A broad, Commercial Presence, and naturalperson mobility. (Movement of Natural Persn) Four modes. The service trade of these four modes has completely different properties and characteristics. Therefore, it is difficult to establish a unified theoretical framework for service trade to affect economic growth. The corresponding literature is very rare. The only foreign documents are mainly Robinson et al. (2002), who simply regard service trade as a commodity. Trade, without taking into account differences in the four trade models, studied the economic growth effects of service trade liberalization using the Computable General Equilibrium (CGE) model.Using empirical methods to study the literature on the impact of overall service trade on economic growth is more, but such studies are mostly domestic scholars. Research shows that the average contribution of China's overall service trade to economic growth is 18.9%.3 Effect of Service Trade in Different Industries on Economic GrowthAt present, the literature on the impact of industry trade in service trade on economic growth is mostly concentrated in such service sectors as finance, telecommunications, and health care. These studies have basically reached a relatively unanimous conclusion that the opening of the service sector or the increase in productivity can significantly promote economic growth. . For example, studies by Beck et al. (1998), M urinde & Ryan (2003), and Eschenbach (2004) suggest that the opening of the financial sector has, to a certain extent, broken the monopoly of domesticfinancial markets and prompted the orderly competition of financial markets. On the normal development track, productivity has improved, and it has finally led to economic growth in the country. Kim (2000) studied the relationship between the development of service trade in the distribution sector and the growth of total factor productivity (TFP) using Korea's input-output data. The results show that the liberalization of service trade not only significantly promoted its own TFP. The promotion also promoted the improvement of total factor productivity in the related manufacturing sector. The total factor productivity growth brought about by service trade almost covered the entire economic sector.4 Effect of Service Trade on Economic Growth by Different Trading ModesThere are few literatures on specific transaction models and theoretical studies on the impact of trade in services on economic growth. Carr et al. (2001) & M arkusen et al. (2005) theoretically examined the commercial existence model by means of the CGE model. The impact of the trade in services on economic growth shows that the opening up of trade in services is an important source of the increase in economic welfare of a country. From the perspective of economic welfare, the opening up of trade in services is a general trend. Subsequently, the use of CGE models to theoretically examine the impact of service trade on economic growth began to prevail. For example, Rutherford et al. (2005)used the CGE model to evaluate Russia's WTO accession effects, and Ko nan &Maskus (2006) used CGE models. The potential effects of Tunisia's elimination of barriers to trade in services were studied. Their conclusions indicate that the increase in the level of economic welfare in one country can benefit from the opening up of the service market, while the elimination of FDI market access barriers in the service sector is a pattern of four trades. The most important liberalization measures are the main sources of increased welfare in a country. There are a lot of literatures on the relationship between service trade and economic growth in specific models using empirical methods. In the four modes of trade in services, commercial presence is the most important one, and from the point of view of data availability, although statistical data is still not very accurate, commercial existence of service trade is based on service industry FDI as a carrier. To achieve this, researchers can use service industry FDI data to characterize the scale of service trade in this model, and this type of trade model has received more attention. Among them, Markusen (1989) believes that the existence of commercial trade in services has two positive and negative effects. The positive effect is that competition in the service sector has led to an increase in domestic demand for the sector’s production factors, which is conducive to output growth. The effect of market size and negative effects means that the intensified competition in the domestic market of service industries has led to the withdrawal ofdomestic service-oriented enterprises from the market. The study by Markusen (1989) shows that the effect of market size after the opening of the service market far exceeds the crowding-out effect. After offsetting the crowding-out effect, it can still promote the productivity improvement of the non-service sector and further lead to the structure of domestic trade in goods. The changes, those sectors that were previously low in productivity and dependent on imports, will evolve into high-productivity export sectors, which is quite similar to the latest research findings on the interactive development of producer services and manufacturing. Hoekman (2006) and Hoekman (2006) used India as an example to examine the impact of the existence of commercial trade in services in the finance, telecommunications, and transportation sectors on the competitiveness of the goods export sector, and believe that these sectors have been liberalized. The level of soft facilities has been increased, which in turn has greatly reduced the operating costs of the downstream product manufacturing sector, which has increased the export competitiveness. With the inefficiency of the domestic service industry, the unfavorable pattern is reversed with the help of commercial presence of service trade. Feasible choice. Guerrieri et al. (2005) took the EU as the research object and analyzed the role of commercial trade in services for knowledge accumulation and economic growth. The study concluded that the openness of the service market or the relaxation of domesticservice regulations has positively promoted economic growth. It was found that the imported service items may be more able to promote economic growth than the domestic same service items due to high technological content.5 Possible Future Research DirectionsIt is not difficult to find from the above-mentioned documents that since the development of service trade started late, research on the growth of service trade began to rise gradually from the 1980s, and more than 20 years of research in this area is in the ascendant. With the further enhancement of the status of trade in services, the possible directions for future research will generally include the following aspects.From the point of view of research methodology, classification of service trade can be studied. As the theory of goods trade has gradually matured, the development practice of service trade still calls for the birth of the theory of service trade. Helpman and Markusen, international economists, expressed on different occasions that the difficulty in establishing the theoretical system of service trade lies in the fact that there are large differences in various types of service trades, and it is difficult for researchers to overcome the gap between them. Classifying service trade according to certain standards and exploring the impact of various types of service trade on economic growth is a possible direction for future research.From the perspective of the research subjects, it is possible to study China’s service trade and economic growth. China’s GDP has already ranked second in the world. However, the service industry’s added value accounted for only 40% of GDP, which is obviously not commensurate with the status of an economic power. In addition, the trade in services is still relatively small compared to the trade in goods. Under such a realistic background, what is the relationship between China's service trade and economic growth? How will service trade contribute to China's economic growth? What impact will service outsourcing have on China's economy? With China in In the next decade, how will China make service trade an engine of economic growth? From the academic point of view, economists from all countries are paying attention to China’s economic development, and China’s service trade will also be improved. It will become a research hotspot.From the perspective of research topics, it is possible to study the impact of service outsourcing on economic growth. In 2008, the scale of global service outsourcing market has reached 1.5 trillion US dollars. According to the UNCTAD (UNCT AD) speculation, the global service outsourcing market will increase by 30%-40% in the next 5-10 years.The surging service industry outsourcing is a new form of service trade. How does service outsourcing drive economic growth through employment, industrial structure upgrading, and technology spillovers?What are the differences in the impact of contracting and receiving services on economic growth in the service industry? Research on these issues will start with the development of service outsourcing to important theoretical guidance.中文译文国际服务贸易与经济增长理论与实证研究Chakraborty Kavin1 引言国际贸易与经济增长始终是国际经济学最生动的论题之一。

外文文献及翻译

外文文献及翻译

外文文献原稿和译文原稿DATABASEA database may be defined as a collection interrelated data store together with as little redundancy as possible to serve one or more applications in an optimal fashion .the data are stored so that they are independent of programs which use the data .A common and controlled approach is used in adding new data and in modifying and retrieving existing data within the data base .One system is said to contain a collection of database if they are entirely separate in structure .A database may be designed for batch processing , real-time processing ,or in-line processing .A data base system involves application program, DBMS, and database.THE INTRODUCTION TO DATABASE MANAGEMENT SYSTEMSThe term database is often to describe a collection of related files that is organized into an integrated structure that provides different people varied access to the same data. In many cases this resource is located in different files in different departments throughout the organization, often known only to the individuals who work with their specific portion of the total information. In these cases, the potential value of the information goes unrealized because a person in other departments who may need it does not know it or it cannot be accessed efficiently. In an attempt to organize their information resources and provide for timely and efficient access, many companies have implemented databases.A database is a collection of related data. By data, we mean known facts that can be recorded and that have implicit meaning. For example, the names, telephone numbers, and addresses of all the people you know. You may have recorded this data in an indexed address book, or you may have stored it on a diskette using a personalcomputer and software such as DBASE Ⅲor Lotus 1-2-3. This is a collection of related data with an implicit meaning and hence is a database.The above definition of database is quite general. For example, we may consider the collection of words that made up this page of text to be usually more restricted. A database has the following implicit properties:● A database is a logically coherent collection of data with some inherent meaning. A random assortment of data cannot be referred to as a database.● A database is designed, built, and populated with data for a specific purpose. It has an intended group of user and some preconceived applications in which these users are interested.● A database represents some aspect of the real world, sometimes called the miniworld. Changes to the miniworld are reflected in the database.In other words, a database has some source from which data are derived, some degree of interaction with events in the real world, and an audience that is actively interested in the contents of the database.A database management system (DBMS) is composed of three major parts: (1) a storage subsystem that stores and retrieves data in files; (2)a modeling and manipulation subsystem that provides the means with which to organize the data and to add, delete, maintain, and update the data; and (3) an interface between the DBMS and its users. Several major trends are emerging that enhance the value and usefulness of database management systems.●Managers who require more up-to-date information to make effective decisions.●Customers who demand increasingly sophisticated information services and more current information about the status of their orders, invoices, and accounts.●Users who find that they can develop custom applications with database systems in a fraction of the time it takes to use traditional programming languages.●Organizations that discover information has a strategic value; they utilize their database systems to gain an edge over their competitors.A DBMS can organize, process, and present selected data elements from the database. This capability enables decision makers to search, probe, and query database contents in order to extract answers to nonrecurring and unplanned questions that aren’t available in regular reports. These questions might initially be vague and/or p oorly defined, but people can “browse” through the database until they have the needed information. In short, the DBMS will “mange” the stored data items and assemble the needed items from the common database in response to the queries of those who aren’t programmers. In a file-oriented system, user needing special information may communicate their needs to a programmer, who, when time permits, will write one or more programs to extract the data and prepare the information. The availability of a DBMS, however, offers users a much faster alternative communications path.DATABASE QUERYIf the DBMS provides a way to interactively enter and update the database ,as well as interrogate it ,this capability allows for managing personal database. However, it does not automatically leave an audit trail of actions and does not provide the kinds of controls necessary in a multi-user organization .There controls are only available when a set of application programs is customized for each data entry and updating function.Software for personal computers that perform some of the DBMS functions has been very popular .Individuals for personal information storage and processing intended personal computers for us .Small enterprises, professionals like doctors, architects, engineers, lawyers and so on have also used these machines extensively. By the nature of intended usage ,database system on there machines are except from several of the requirements of full-fledged database systems. Since data sharing is not intended, concurrent operations even less so ,the software can be less complex .Security and integrity maintenance are de-emphasized or absent .as data volumes will be small, performance efficiency is also less important .In fact, the only aspect of a database system that is important is data independence. Data independence ,as stated earlier ,means that application programs and user queries need not recognize physical organization of data on secondary storage. The importance of this aspect , particularly for the personal computer user ,is that this greatly simplifies database usage . The user can store ,access and manipulate data at ahigh level (close to the application)and be totally shielded from the low level (close to the machine )details of data organization.DBMS STRUCTURING TECHNIQUESSpatial data management has been an active area of research in the database field for two decades ,with much of the research being focused on developing data structures for storing and indexing spatial data .however, no commercial database system provides facilities for directly de fining and storing spatial data ,and formulating queries based on research conditions on spatial data.There are two components to data management: history data management and version management .Both have been the subjects of research for over a decade. The troublesome aspect of temporal data management is that the boundary between applications and database systems has not been clearly drawn. Specifically, it is not clear how much of the typical semantics and facilities of temporal data management can and should be directly incorporated in a database system, and how much should be left to applications and users. In this section, we will provide a list of short-term research issues that should be examined to shed light on this fundamental question.The focus of research into history data management has been on defining the semantics of time and time interval, and issues related to understanding the semantics of queries and updates against history data stored in an attribute of a record. Typically, in the context of relational databases ,a temporal attribute is defined to hold a sequence of history data for the attribute. A history data consists of a data item and a time interval for which the data item is valid. A query may then be issued to retrieve history data for a specified time interval for the temporal attribute. The mechanism for supporting temporal attributes is to that for supporting set-valued attributes in a database system, such as UniSQL.In the absence of a support for temporal attributes, application developers who need to model and history data have simply simulated temporal attributes by creating attribute for the time interval ,along with the “temporal” attribute. This of course may result in duplication of records in a table, and more complicated search predicates in queries. The one necessary topic of research in history data management is to quantitatively establish the performance (and even productivity) differences betweenusing a database system that directly supports attributes and using a conventional database system that does not support either the set-valued attributes or temporal attributes.Data security, integrity, and independenceData security prevents unauthorized users from viewing or updating the database. Using passwords, users are allowed access to the entire database of the database, called subschemas. For example, an employee database can contain all the data about an individual employee, but one group of users may be authorized to view only payroll data, while others are allowed access to only work history and medical data.Data integrity refers to the accuracy, correctness, or validity of the data in the database. In a database system, data integrity means safeguarding the data against invalid alteration or destruction. In large on-line database system, data integrity becomes a more severe problem and two additional complications arise. The first has to do with many users accessing the database concurrently. For example, if thousands of travel agents book the same seat on the same flight, the first agent’s booking will be lost. In such cases the technique of locking the record or field provides the means for preventing one user from accessing a record while another user is updating the same record.The second complication relates to hardware, software or human error during the course of processing and involves database transaction which is a group of database modifications treated as a single unit. For example, an agent booking an airline reservation involves several database updates (i.e., adding the passenger’s name and address and updating the seats-available field), which comprise a single transaction. The database transaction is not considered to be completed until all updates have been completed; otherwise, none of the updates will be allowed to take place.An important point about database systems is that the database should exist independently of any of the specific applications. Traditional data processing applications are data dependent.When a DMBS is used, the detailed knowledge of the physical organization of the data does not have to be built into every application program. The application program asks the DBMS for data by field name, for example, a coded representationof “give me customer name and balance due” would be sent to the DBMS. Without a DBMS the programmer must reserve space for the full structure of the record in the program. Any change in data structure requires changes in all the applications programs.Data Base Management System (DBMS)The system software package that handles the difficult tasks associated with creating ,accessing and maintaining data base records is called a data base management system (DBMS). A DBMS will usually be handing multiple data calls concurrently.It must organize its system buffers so that different data operations can be in process together .It provides a data definition language to specify the conceptual schema and most likely ,some of the details regarding the implementation of the conceptual schema by the physical schema.The data definition language is a high-level language, enabling one to describe the conceptual schema in terms of a “data model “.At the present time ,there are four underling structures for database management systems. They are :List structures.Relational structures.Hierarchical (tree) structures.Network structures.Management Information System(MIS)An MIS can be defined as a network of computer-based data processing procedures developed in an organization and integrated as necessary with manual and other procedures for the purpose of providing timely and effective information to support decision making and other necessary management functions.One of the most difficult tasks of the MIS designer is to develop the information flow needed to support decision making .Generally speaking ,much of the information needed by managers who occupy different levels and who have different levels and have different responsibilities is obtained from a collection of exiting information system (or subsystems)Structure Query Language (SQL)SQL is a data base processing language endorsed by the American NationalStandards Institute. It is rapidly becoming the standard query language for accessing data on relational databases .With its simple ,powerful syntax ,SQL represents a great progress in database access for all levels of management and computing professionals.SQL falls into two forms : interactive SQL and embedded SQL. Embedded SQL usage is near to traditional programming in third generation languages .It is the interactive use of SQL that makes it most applicable for the rapid answering of ad hoc queries .With an interactive SQL query you just type in a few lines of SQL and you get the database response immediately on the screen.译文数据库数据库可以被定义为一个相互联系的数据库存储的集合。

外文翻译中英文对照

外文翻译中英文对照

Strengths优势All these private sector banks hold strong position on CRM part, they have professional, dedicated and well-trained employees.所以这些私人银行在客户管理部分都持支持态度,他们拥有专业的、细致的、训练有素的员工。

Private sector banks offer a wide range of banking and financial products and financial services to corporate and retail customers through a variety of delivery channels such as ATMs, Internet-banking, mobile-banking, etc. 私有银行通过许多传递通道(如自动取款机、网上银行、手机银行等)提供大范围的银行和金融产品、金融服务进行合作并向客户零售。

The area could be Investment management banking, life and non-life insurance, venture capital and asset management, retail loans such as home loans, personal loans, educational loans, car loans, consumer durable loans, credit cards, etc. 涉及的领域包括投资管理银行、生命和非生命保险、风险投资与资产管理、零售贷款(如家庭贷款、个人贷款、教育贷款、汽车贷款、耐用消费品贷款、信用卡等)。

Private sector banks focus on customization of products that are designed to meet the specific needs of customers. 私人银行主要致力于为一些特殊需求的客户进行设计和产品定制。

毕业设计外文翻译英文加中文

毕业设计外文翻译英文加中文

A Comparison of Soft Start Mechanisms for Mining BeltConveyors1800 Washington Road Pittsburgh, PA 15241 Belt Conveyors are an important method for transportation of bulk materials in the mining industry. The control of the application of the starting torque from the belt drive system to the belt fabric affects the performance, life cost, and reliability of the conveyor. This paper examines applications of each starting method within the coal mining industry.INTRODUCTIONThe force required to move a belt conveyor must be transmitted by the drive pulley via friction between the drive pulley and the belt fabric. In order to transmit power there must be a difference in the belt tension as it approaches and leaves the drive pulley. These conditions are true for steady state running, starting, and stopping. Traditionally, belt designs are based on static calculations of running forces. Since starting and stopping are not examined in detail, safety factors are applied to static loadings (Harrison, 1987). This paper will primarily address the starting or acceleration duty of the conveyor. The belt designer must control starting acceleration to prevent excessive tension in the belt fabric and forces in the belt drive system (Suttees, 1986). High acceleration forces can adversely affect the belt fabric, belt splices, drive pulleys, idler pulleys, shafts, bearings, speed reducers, and couplings. Uncontrolled acceleration forces can cause belt conveyor system performance problems with vertical curves, excessive belt take-up movement, loss of drive pulley friction, spillage of materials, and festooning of the belt fabric. The belt designer is confronted with two problems, The belt drive system must produce a minimum torque powerful enough to start the conveyor, and controlled such that the acceleration forces are within safe limits. Smooth starting of the conveyor can be accomplished by the use of drive torque control equipment, either mechanical or electrical, or a combination of the two (CEM, 1979).SOFT START MECHANISM EVALUATION CRITERIONWhat is the best belt conveyor drive system? The answer depends on many variables. The best system is one that provides acceptable control for starting, running, and stopping at a reasonable cost and with high reliability (Lewdly and Sugarcane, 1978). Belt Drive System For the purposes of this paper we will assume that belt conveyors are almost always driven byelectrical prime movers (Goodyear Tire and Rubber, 1982). The belt "drive system" shall consist of multiple components including the electrical prime mover, the electrical motor starter with control system, the motor coupling, the speed reducer, the low speed coupling, the belt drive pulley, and the pulley brake or hold back (Cur, 1986). It is important that the belt designer examine the applicability of each system component to the particular application. For the purpose of this paper, we will assume that all drive system components are located in the fresh air, non-permissible, areas of the mine, or in non-hazardous, National Electrical Code, Article 500 explosion-proof, areas of the surface of the mine.Belt Drive Component Attributes SizeCertain drive components are available and practical in different size ranges. For this discussion, we will assume that belt drive systems range from fractional horsepower to multiples of thousands of horsepower. Small drive systems are often below 50 horsepower. Medium systems range from 50 to 1000 horsepower. Large systems can be considered above 1000 horsepower. Division of sizes into these groups is entirely arbitrary. Care must be taken to resist the temptation to over motor or under motor a belt flight to enhance standardization. An over motored drive results in poor efficiency and the potential for high torques, while an under motored drive could result in destructive overspending on regeneration, or overheating with shortened motor life (Lords, et al., 1978).Torque ControlBelt designers try to limit the starting torque to no more than 150% of the running torque (CEMA, 1979; Goodyear, 1982). The limit on the applied starting torque is often the limit of rating of the belt carcass, belt splice, pulley lagging, or shaft deflections. On larger belts and belts with optimized sized components, torque limits of 110% through 125% are common (Elberton, 1986). In addition to a torque limit, the belt starter may be required to limit torque increments that would stretch belting and cause traveling waves. An ideal starting control system would apply a pretension torque to the belt at rest up to the point of breakaway, or movement of the entire belt, then a torque equal to the movement requirements of the belt with load plus a constant torque to accelerate the inertia of the system components from rest to final running speed. This would minimize system transient forces and belt stretch (Shultz, 1992). Different drive systems exhibit varying ability to control the application of torques to the belt at rest and at different speeds. Also, the conveyor itself exhibits two extremes of loading. An empty belt normally presents the smallest required torque for breakaway and acceleration, while a fully loaded belt presents the highest required torque. A mining drive system must be capable of scaling the applied torque from a 2/1 ratio for a horizontal simple belt arrangement, to a 10/1 ranges for an inclined or complex belt profile.Thermal RatingDuring starting and running, each drive system may dissipate waste heat. The waste heat may be liberated in the electrical motor, the electrical controls,, the couplings, the speed reducer, or the belt braking system. The thermal load of each start Is dependent on the amount of belt load and the duration of the start. The designer must fulfill the application requirements for repeated starts after running the conveyor at full load. Typical mining belt starting duties vary from 3 to 10 starts per hour equally spaced, or 2 to 4 starts in succession. Repeated starting may require the dreading or over sizing of system components. There is a direct relationship between thermal rating for repeated starts and costs. Variable Speed. Some belt drive systems are suitable for controlling the starting torque and speed, but only run at constant speed. Some belt applications would require a drive system capable of running for extended periods at less than full speed. This is useful when the drive load must be shared with other drives, the belt is used as a process feeder for rate control of the conveyed material, the belt speed is optimized for the haulage rate, the belt is used at slower speeds to transport men or materials, or the belt is run a slow inspection or inching speed for maintenance purposes (Hager, 1991). The variable speed belt drive will require a control system based on some algorithm to regulate operating speed. Regeneration or Overhauling Load. Some belt profiles present the potential for overhauling loads where the belt system supplies energy to the drive system. Not all drive systems have the ability to accept regenerated energy from the load. Some drives can accept energy from the load and return it to the power line for use by other loads. Other drives accept energy from the load and dissipate it into designated dynamic or mechanical braking elements. Some belt profiles switch from motoring to regeneration during operation. Can the drive system accept regenerated energy of a certain magnitude for the application? Does the drive system have to control or modulate the amount of retarding force during overhauling? Does the overhauling occur when running and starting? Maintenance and Supporting Systems. Each drive system will require periodic preventative maintenance. Replaceable items would include motor brushes, bearings, brake pads, dissipation resistors, oils, and cooling water. If the drive system is conservatively engineered and operated, the lower stress on consumables will result in lower maintenance costs. Some drives require supporting systems such as circulating oil for lubrication, cooling air or water, environmental dust filtering, or computer instrumentation. The maintenance of the supporting systems can affect the reliability of the drive system.CostThe drive designer will examine the cost of each drive system. The total cost is the sum of the first capital cost to acquire the drive, the cost to install and commission the drive, thecost to operate the drive, and the cost to maintain the drive. The cost for power to operate the drive may vary widely with different locations. The designer strives to meet all system performance requirements at lowest total cost. Often more than one drive system may satisfy all system performance criterions at competitive costs.ComplexityThe preferred drive arrangement is the simplest, such as a single motor driving through a single head pulley.However,mechanical, economic,and functional requirements often necessitate the use of complex drives.The belt designer must balance the need for sophistication against the problems that accompany complex systems. Complex systems require additional design engineering for successful deployment. An often-overlooked cost in a complex system is the cost of training onsite personnel, or the cost of downtime as a result of insufficient training.SOFT START DRIVE CONTROL LOGICEach drive system will require a control system to regulate the starting mechanism. The most common type of control used on smaller to medium sized drives with simple profiles is termed "Open Loop Acceleration Control". In open loop, the control system is previously configured to sequence the starting mechanism in a prescribed manner, usually based on time. In open loop control, drive-operating parameters such as current, torque, or speed do not influence sequence operation. This method presumes that the control designer has adequately modeled drive system performance on the conveyor. For larger or more complex belts, "Closed Loop" or "Feedback" control may he utilized. In closed loop control, during starting, the control system monitors via sensors drive operating parameters such as current level of the motor, speed of the belt, or force on the belt, and modifies the starting sequence to control, limit, or optimize one or wore parameters. Closed loop control systems modify the starting applied force between an empty and fully loaded conveyor. The constants in the mathematical model related to the measured variable versus the system drive response are termed the tuning constants. These constants must be properly adjusted for successful application to each conveyor. The most common schemes for closed loop control of conveyor starts are tachometer feedback for speed control and load cell force or drive force feedback for torque control. On some complex systems, It is desirable to have the closed loop control system adjust itself for various encountered conveyor conditions. This is termed "Adaptive Control". These extremes can involve vast variations in loadings, temperature of the belting, location of the loading on the profile, or multiple drive options on the conveyor. There are three commonadaptive methods. The first involves decisions made before the start, or 'Restart Conditioning'. If the control system could know that the belt is empty, it would reduce initial force and lengthen the application of acceleration force to full speed. If the belt is loaded, the control system would apply pretension forces under stall for less time and supply sufficient torque to adequately accelerate the belt in a timely manner. Since the belt only became loaded during previous running by loading the drive, the average drive current can be sampled when running and retained in a first-in-first-out buffer memory that reflects the belt conveyance time. Then at shutdown the FIFO average may be use4 to precondition some open loop and closed loop set points for the next start. The second method involves decisions that are based on drive observations that occur during initial starting or "Motion Proving'. This usually involves a comparison In time of the drive current or force versus the belt speed. if the drive current or force required early in the sequence is low and motion is initiated, the belt must be unloaded. If the drive current or force required is high and motion is slow in starting, the conveyor must be loaded. This decision can be divided in zones and used to modify the middle and finish of the start sequence control. The third method involves a comparison of the belt speed versus time for this start against historical limits of belt acceleration, or 'Acceleration Envelope Monitoring'. At start, the belt speed is measured versus time. This is compared with two limiting belt speed curves that are retained in control system memory. The first curve profiles the empty belt when accelerated, and the second one the fully loaded belt. Thus, if the current speed versus time is lower than the loaded profile, it may indicate that the belt is overloaded, impeded, or drive malfunction. If the current speed versus time is higher than the empty profile, it may indicate a broken belt, coupling, or drive malfunction. In either case, the current start is aborted and an alarm issued.CONCLUSIONThe best belt starting system is one that provides acceptable performance under all belt load Conditions at a reasonable cost with high reliability. No one starting system meets all needs. The belt designer must define the starting system attributes that are required for each belt. In general, the AC induction motor with full voltage starting is confined to small belts with simple profiles. The AC induction motor with reduced voltage SCR starting is the base case mining starter for underground belts from small to medium sizes. With recent improvements, the AC motor with fixed fill fluid couplings is the base case for medium to large conveyors with simple profiles. The Wound Rotor Induction Motor drive is the traditional choice for medium to large belts with repeated starting duty or complex profilesthat require precise torque control. The DC motor drive, Variable Fill Hydrokinetic drive, and the Variable Mechanical Transmission drive compete for application on belts with extreme profiles or variable speed at running requirements. The choice is dependent on location environment, competitive price, operating energy losses, speed response, and user familiarity. AC Variable Frequency drive and Brush less DC applications are limited to small to medium sized belts that require precise speed control due to higher present costs and complexity. However, with continuing competitive and technical improvements, the use of synthesized waveform electronic drives will expand.REFERENCES[1]Michael L. Nave, P.E.1989.CONSOL Inc.煤矿业带式输送机几种软起动方式的比较1800 年华盛顿路匹兹堡, PA 15241带式运送机是采矿工业运输大批原料的重要方法。

采矿工程 毕业设计_外文翻译 英译汉 中英文

采矿工程 毕业设计_外文翻译 英译汉 中英文

ROOM-AND-PILLAR METHOD OF OPEN-STOPE MINING空场采矿法中的房柱采矿法Chapter 1.A Classification of the Room-and-Pillar Method of Open-Stope Mining第一部分,空场采矿的房柱法的分类OPEN STOPING空场采矿法An open stope is an underground cavity from which the initial ore has been mined. Caving of the opening is prevented (at least temporarily) by support from the unmined ore or waste left in the stope,in the form of pillars,and the stope walls (also called ribs or abutments). In addition to this primary may also be required using rockbolts , reinforcing rods, split pipes ,or shotcrete to stabilize the rock surface immediately adjacent to the opening. The secondary reinforcement procedure does not preclude the method classified as open stoping.露天采场台阶是开采了地下矿石后形成的地下洞室。

通过块矿或采场的支柱和(也称为肋或肩)采场墙形式的废料的支持来(至少是暂时的)预防放顶煤的开幕。

除了这个,可能还需要使用锚杆,钢筋棒,分流管,或喷浆,以稳定紧邻开幕的岩石表面。

外文文献及翻译

外文文献及翻译

Yunnan Ethnic pattern in Packaging DesignAbstract: Art is a folk Mother of the arts,is the source of the new art, From which to draw a strong tradition of high—grade Nutrition。

The persons belonging to national folk arts Ethnic patterns,are folk arts Intraoperative a gem, its development Research,and with the means of modern art,art wind Grid,professional skills combine to form a unique Style and features a modern design There are important applications,this paper focuses on Minority Folk pattern in modern packaging design Meter applications are discussed.Keywords: Yunnan Ethnic. Pattern。

Packaging Design.IntroductionYunnan is a multi-ethnic province, Here multiply survive the Han, Yi, Bai More than twenty families, Zhuang, Miao, Dai, etc。

Nation. Long history of various ethnic groups in Yunnan Province, the source is far Long, creating a rich and colorful Folk art。

土木中外文翻译

土木中外文翻译

On The Application of High-Performance Concrete Summary The high-performance concrete is a main direction of the technical development of recent concrete, the foreign scholar has called that the concrete in 21st century. Norway carried on research to this at first in 1986, named formally from American National Standard, technological research institute (NIST) and a seminar hosted together of American Concrete Institute (ACI) in 1990. Conference stipulate high-performance concrete to have whom some performance require homogenize the concrete, must adopt the strict construction craft, adopt high-quality material formulate, easy to water smash, emanate, mechanics performance steady, early intensity high, with performance such as toughness and volume stability durable concrete, especially suitable for the skyscraper, bridge and open to the building structure of the harsh environment.Key words concrete; performance; engineering; application1.IntroductionRecent high-performance concrete is the main direction of the development of concrete technology, foreign scholars have called the 21st century concrete. Norway in 1986, this was the first study in 1990 by the National Institute of Standards and Technology (NIST) and the American Concrete Institute (ACI) at a seminar co-hosted a formal naming. The General Assembly for high-performance concrete is a certain performance requirements of the uniform quality of concrete, it must adopt a strict construction technology, using high-quality materials, preparation, ease of pouring pound, non-segregation, mechanical properties and stability, high early strength with toughness and size stability durability performance of concrete, especially for high-rise buildings, bridges, and exposure to harsh environments in architectural structures. As an integrated high-performance concrete with excellent technical characteristics of materials at home and abroad has aroused world wide attention with the engineering and concern. 10 years, the world, many countries have invested a great deal of manpower, financial and material resources to conduct the research and development applications, to enable high-performance concrete technology has made great progress in the selection of raw materials, mix design, physical and mechanical properties of , durability, workability, structure and performance as well as application of technology have made both theoretical basis and its practical value of scientific and technological achievements.In 1993, the technical committee under American Concrete Institute proposed a new high-performance concrete was defined: Meet project special various performance of requirement, but including easy to water, smash instead of emanating, high long-term mechanics performance, high early intensity, high and tough and tensile and high volume stability, or the service life in the harsh environment is for a long time, and homogenizing good concrete. In recent years, American Concrete Institute provides more concise definitionon a piece of characters again: "The high-performance concrete is that one kind can accord with special performance and synthesize the concrete with the homogeneity requirement, the concrete can get with regular concrete component material and common mixing, habit method smashed and maintained to water often. "High-performance concrete, it is used for signifying the concrete with high work degree, high strength and high durability beginning. This kind of concrete must be designed and possessed high volume stability.For reduce concrete shrink and do fracture produced to contract with temperature, must limit the grout content in the concrete mixture. The high-performance concrete amount of total grout limited of design method of match ratio that Mehta and Actcin put forward is 1/3 of the concrete volume; Allow some silicate cement spend volcanic ash or have glue person who congeal to mix, shut material replace. AcTcin has been prophesied: Mix slay, fly ash, silica flour, inferior clay, the rice husks dust and three yuan of the lime stone powder and mix cement besides can make the preparation of the high-performance concrete more economic ing, still can give play to exceeding a pile of function of them, improve its property while mixing and hardening newly.2.High performance concrete in modern engineeringHigh performance concrete technology is successfully used in many parts of the world of offshore structures and grew up across the bridge construction, Langley, who described growing up across a few bridges in Canada with the workability.They are used in the girder, mound department and mound base, it is 450 Kg/m3 that silica flour mix cement consumption, water 153L/ m3, guide angry pharmaceutical 160mL/ m3 and high-efficient water-reducing agent 3L/ m3. Its slump is probably in 200mm; Includes 6.1% of tolerance; 1d, 3d, 28d compression strength are 35, 52 and 82 MPa respectively; The foundation and other big mixed cement consumption of pieces of concrete are 307 Kg/m3, fly ash 133 Kg/m3, water consumption is close, but guide the angry pharmaceutical and mixing amount of high-efficient water-reducing agent to reduce by a large margin, make an appointment in 185mm in slump; Includes 7% of tolerance; 1d, 3d, 28d and 90d compression strength are 10, 20, 50 and 76 MPa respectively. And water permeability of U.S.A. and chlorine ion fast to permeate standard method experimental result indicate according to Canada: Both part of concretes present very low permeability. To high-performance concrete construction of structure, need, put emphasis on, strengthen on-the-spot laboratory test and inspection of quality very much.Another area of development of high performance concrete is a high performance lightweight concrete, as opposed to steel, ordinary concrete strength / weight ratio is very low,mixed with high-strength concrete superplasticizer is significantly enhanced the ratio; with a large number of tiny holes lightweight aggregate to replace part of the normal aggregate, will be able to further improve this ratio. As the aggregate quality of different density of 2000 Kg/m3, compressive strength at 70 ~ 80 MPa high-performance lightweight concrete in a number of countries have already commercialized and used in component production. In Australia, Canada, Japan, Norway and the United States, high-performance lightweight concrete has been used in fixed and floating drilling platform; because of mud and water, the interface between the aggregate bond strength, it can be impermeable, so the erosion of the environment able is very durable.-Doped silica powder 10 ~ 15% or even higher superplasticizer prepared mixture of cement concrete, with excellent adhesion, so the spray applied to the wet spraying the structural repair of concrete, which is one of the areas of high performance concrete applications .High-performance concrete (> 40MPa) over the first 30-story high-rise buildings used for reinforced concrete structures, because such buildings in the lower third of the columns, using ordinary concrete when the great cross-section. In addition to savings in material costs, as compared with the steel structure, speeding up the adoption of concrete structures is an important feature, since the United States in Chicago in 1965 with 50 MPa concrete pouring Lake Point Tower some of the pillars has been everywhere in North America and other countries using high-performance concrete to build high-rise building. Chicago 79-story Water Tower Place building columns using 60MPa concrete; Toronto's Scotia Plaza Building and Seattle's Two union Square Building 2 Buildings then 90 and 120MPa respectively intensity of high-performance concrete pillars.Application examples: a. high-performance concrete application of C80 high-strength and high-performance concrete in Shenyang Fangyuan Building, Onishi Electric Park, and many other high-rise building in the application of concrete filled steel tubular columns.b. Shanghai Research in the field of high performance concrete in a large number of promising results obtained, of which representative results are: China's tallest building - 88 C40 floor Jinmao Tower once pumped to 382.5m; Tomorrow Square slag pumping C80 concrete; in Shanghai education TV station based on complex building mass concrete, cement consumption accounted for only 46% of the total cementitious materials, preparation of the full amount of concrete slurry, concrete work, cohesiveness and resistance to segregation are very excellent performance, strength of C40 high-performance concrete.2.2 High-performance pavement concretea. High-performance pavement concrete significance of the studyWith the increasing traffic and transport requirements to develop the "long-life low-maintenance road,"With high-performance pavement concrete, to improve the flexural strength and durability of concrete is the current trend of development of concrete pavement.b. Overseas developmentsHeld in 1997 at the XVI International Conference on Concrete Pavement, pavement design proposed not only to raise the average intensity of demand, but also make the durability requirements. Made in the direction of future development of ultra-high tensile strength up to 17MPa strength concrete, for paving continuous concrete pavement. Improve the concrete pavement surface compactness and impermeability are very important, and this is through high-performance concrete to achieve.c. High-performance pavement concrete strengthHigh-performance concrete pavement important feature is a high flexural strength. Using high-performance pavement concrete can significantly improve the bearing capacity of pavement, extend service life, or thinning the thickness of pavement to reduce the project cost.d. High-performance durability of concrete pavementHigh-performance concrete pavement main feature is a sufficient durability, resistant to climatic and environmental effects of long-term damage to ensure that the design of pavement and within the concrete can work properly.e. High deformation characteristics of concrete pavement(1) ShrinkageRoad panel surface area of great evaporation, shrinkage may be caused by Tao panel surface of shrinkage cracks, the need to increase conservation.(2) The flexural modulus of elasticityHigh-performance pavement concrete flexural elastic modulus E, by measurement, one for 4.305104Mpa, 2 grade 4.845104Mpa, 3 grade 4.605104Mpa. Intensity of three high-performance pavement concrete mix, the aggregate amount of less coarse aggregate maximum particle diameter is smaller.f. The application ofApplication of high-performance pavement concrete yield significant benefits:(1) increase pavement strength;(2) extend the pavement service life;(3) reducing the project cost;g. Applications(1) in the U.S. about 70% of the road pavement using high-performance concrete: one in North Dakota, 1988 and 1989 in the summer, with 20000m3 of concrete paving thickness of 200 mm of the surface, its water-cement ratio of 0.43, cement consumption 100 Kg/m3, fly ash 220 Kg/m3; the road Texas demonstration project has successfully adopted this new material.(2) The Qinghai-Tibet railway construction project fully promote the use ofh. ConclusionThree intensity levels of high-performance pavement concrete is extremely good quality, cost of materials basically does not increase or increased marginally, for the different requirements of the project choose to use, the construction of low-maintenance long-life pavement, road, its social, economic benefits are enormous, and worth promoting and continued research to promote the country's airports cement concrete pavement construction and road pavement engineering is entering a new stage of development to meet the growing demand for aviation and transportation needs.2.3 Marine Concrete Structures- Durability of hydraulic structures to enhance port study and propose technical and economic rational, easy to promote the use of a new marine engineering high-performance concreteSpan bridges, undersea tunnels and offshore oil platforms, is an instance of this application.Such as: a, Shantou, Hong Kong outside the Deepwater Channel Regulation Project; b Lingdingyang Pearl River Estuary Deepwater Channel Regulation Project;c, Qingdao, Ningbo Beilun and other ports that can berth 200,000-ton class built tankers and ore ships deep-water berths2.4 Free Vibration of Self-compacting ConcreteDue to vibration-free self-compacting concrete has a very good work, making the concrete filling, compactness, uniformity has been significantly improved, becoming a new concrete technology, progress is listed as a family of high performance concrete.Vibration-free self-compacting concrete is the first study from Japan over the last decade to develop and put into a modern concrete engineering technology. Since vibration-free self-compacting concrete in engineering applications can be made to improve concrete quality,improve concrete construction operations, to support the construction noise and improve labor productivity, speed up the construction cost reduction and other technical and economic effect, in recent years have given the world great pay attention to. Japan is expected by 2003 there will be 1 / 2 works with the free vibration of concrete self-compacting concrete pouring.As the name suggests, vibration-free self-compacting concrete is poured concrete, when self-gravity alone without any external force tamping to achieve self-compacting, self-leveling of a concrete. Vibration-free Self-compacting concrete should have three characteristics:(1) Mobility;(2) Good stability - does not disintegrate;(3) Reinforcement and templates in any gap, with a good through capacity, does not produce blocking.According to the requirements of these three characteristics, vibration-free preparation of self-compacting concrete principles and methods section are as follows:Fresh concrete phase is a particle suspended solids, the continuous medium is a cement paste, which is liquid and Concrete Aggregates, compared with solid-phase. All the particles in suspension, mobility and particle balance between segregation is necessary. Free vibration of fresh self-compacting concrete in the absence of external force to be real concrete formwork to give full fill all the gaps and achieve the compact, more importantly, to both good fluidity and stability.In order to obtain high mobility, we must first reduce the friction between the particles. Incorporation of superplasticizer to reduce the surface tension of particles of course is necessary, but vibration-free performance requirements of self-compacting of view, alone doped superplasticizer was also difficult to achieve, needs to mixed with a certain amount of ultra-fine material.To obtain good stability, so that materials are not disintegrate, the liquid must have the appropriate rheology, can not produce bleeding and prevent particle segregation. To achieve this request, also be mixed with an appropriate amount of particle size <0.25mm fine filler and in some cases mixed with viscosity modifying agent (tackifier).In order to be able to flow through the reinforcement of concrete and templates in the gap without creating any obstruction, in addition to the design of engineering structures be selected according to the appropriate particle size and morphology of aggregates, the liquid volume is the amount of its rheological properties important parameters. The rheological properties is based on the Bingham rheological model used to evaluate the viscometer, andshould have a low yield stress and plastic viscosity appropriate.By rheological point of view, vibration-free matrix of self-compacting concrete is a free flow of ultra-fine paste, the paste is made of cement and composed of fine material, the liquid surrounding the solid particles with the thickness of the serosal layer increases with the increase, while the serosal layer thickness of solid particles in the paste has been filled before the gap between the formation, therefore, the thickness of the slurry affects the shapes by solid particles. For the paste, apart from the requirements of high liquidity, the need of sufficient high viscosity, must be a high-viscosity Newtonian fluid, in order to prevent segregation.Vibration-free self-compacting concrete preparation process as shown.Cement↓Ultra-fine admixture of water superplasticizer↓ ↓ ↓The free flow of slurry of fine aggregate↓ ↓The free flow of mortar of coarse aggregate↓ ↓Self-compacting ConcreteVibration-free self-compacting concrete mix design, first make sure the gap under the aggregate liquid volume of content needed. The composition of the liquid cement, water, additives, and <0.25mm ultra-fine material. Super fine materials and the total aggregate volume ratio (S / A) is free of vibration of self-compacting concrete mix design in an important parameter. Zhen-ming, the mobility of self-compacting concrete will be with the S / A increased with the increase, while the elastic modulus of no significant impact. Basically, according to the required water-cement ratio to determine the compressive strength of concrete. Vibration-free self-compacting concrete due to the rheological behavior of volume and composition of the material has a very close relationship, therefore, vibration-free self-compacting concrete mix design is recommended rather than weight ratio of the volume ratio.3.High-performance concrete in terms of performance on the remaining problems and to improve the wayPreparation of high-performance concrete is characterized by low water-cement ratio, and mixed with a sufficient number of fine mineral admixtures and superplasticizer, so concrete has excellent technical characteristics of an integrated, but this also produced two worthy of attention Performance deficiencies: (1) self-desiccation caused by autogenous shrinkage; (2) brittle.ConclusionResearch and development of high performance concrete application of traditional concrete major breakthrough in technical performance, energy conservation, quality, engineering economic, environmental and labor protection and other aspects of great importance. It is expected that high performance concrete in engineering applications will rapidly expand, and achieve greater, more technical and economic benefits.浅析高性能混凝土的应用摘要:高性能混凝土是近期混凝土技术发展的主要方向,国外学者曾称之为21世纪混凝土。

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通过压模具定制橡胶模面的紧压,使热复合材料层压板部分固化、固结丹尼尔²乌里扎克贾瑞恩²古波斯凯西霍夫曼机械部,航空航天,核工程,伦斯勒理工学院,110八街,特洛伊,纽约12180收稿日期:2010年6月23日,修订:2010年11月13日,出版日期:2011年1月5日制造商规定:热固性复合材料固化巩固层压板夹层结构时,通常需要真空装袋,形成一个较薄壁模具,放置在一釜中,它服从整个机组温度,真空,压力周期。

通常认为高压灭菌由于消耗高资金和生产成本,产生废物和处理的可扩展性成为阻碍使用先进复合材料的主要瓶颈。

一个称为“热按固化”的固化整合过程,被提出并证明可以作为替代高压灭菌的方法。

该设计过程涉及一套特殊模具压缩的复合层压,一个加热的金属模具和配套橡胶覆盖的模具被制成绝缘材料,以提供均匀的金属模具表面温度和压力,也就是模仿由一个高压灭菌器提供的工艺条件。

热固化过程是证明第一次使用一个简单的二维轴对称形状设置一个模的时间。

嵌入式铝固化炉电阻盒模具设计启发并提供在模具表面上统一操作温度为177℃的一个目标值。

模具集压缩八层碳/环氧复合材料工件福祉各方面隔音,比同等蒸压减少操作可能显着提高的压力,均匀压缩橡胶面具所表现出的形状改变的面具功耗至少有一到两个数量级的降低。

即使没有一个优化的橡胶层形状和厚度,八铺设复合材料零件也已经成功实验完成。

今后工作计划在以下文章中所讨论。

© 2011年美国机械工程师学会目录内容简介............................................ 错误!未定义书签。

背景............................................ 错误!未定义书签。

热紧压固化 ...................................... 错误!未定义书签。

A、注射模设计................................. 错误!未定义书签。

B、模具制造................................... 错误!未定义书签。

C、橡胶面具制作............................... 错误!未定义书签。

D、热紧压固化工艺 ............................. 错误!未定义书签。

设计二维热硫化紧压模具制作........................ 错误!未定义书签。

工艺示范........................................ 错误!未定义书签。

A、热特性..................................... 错误!未定义书签。

B、压力表征................................... 错误!未定义书签。

统计表........................................... 错误!未定义书签。

结论和工作计划.................................... 错误!未定义书签。

答谢.. (10)参考文献 (10)简介全球复合材料市场(航空航天,汽车,坦克和管道,海洋,体育用品,风力能源,电力,建筑,铁路,工业领域)预计将达到2014亿美元的规模。

特定的细分市场预期具有最高的年度增长率,包括建造业(20%),交通(15%),航空(10%),风能(10%),以及管道和罐(10%)。

先进的热固性复合材料 - 聚合物如环氧树脂,乙烯基酯基质,以不饱和聚酯(UP)的树脂具有高强度钢筋,高模量增强,如碳纤维或芳纶 - 目前弥补市场的10%(与90%玻璃纤维),而需求预计增长,因为它们的结构和加工可以根据工程应用中需要的那样-高强度,高刚度,低重和/低导热性。

例如,碳纤维复合材料市场全球经济增长预计将增长10%,到2014年每年为24亿美元。

连续纤维增强热塑性塑料(矩形钢管混凝土)复合材料也将越来越大(即12%的预期增长速度在今后五年是两千万美元在2014年为[3]),因为简单制造(无固化要求),而且在许多高韧性的案件。

然而,热固性复合材料目前在市场占主导地位,并会在不久的将来继续这样做。

虽然复合材料通常比金属及其合金工程昂贵(例如,〜$ 15-50/kg航天级碳/比>环氧树脂预浸结构钢1/kg美元),限制其使用的主要原因之一是产品和部件的制造时间和费用很高。

有可用影响包括手上篮,树脂传递成型,面板贴合,喷雾式,大宗模塑料成型/片状模塑料(BMC的/校董会),纤维缠绕,注塑成型,拉挤成型热固性复合材料部件的许多过程。

提到这些,最流行的工艺是先进的热固性材料(即总数的14%的市场份额占[1])预浸渍树脂复合材料部件(称为“半固化片”),要么是手织/单向纤维上篮其次是蒸压养护格式。

一个典型的制造步骤包括以下顺序:1、去除从冷库热固性预浸辊,并允许它达到室温2、削减个人预浸层使用计算机数值控制(CNC)与真空按住成“洁”表及装配层刀3、工作到一个单独的手硫化模具(又名“手上篮”)或通过使用简单的工具和核心的热量(例如,热风枪),形成复合或夹层。

4、真空装袋未固化的复合材料的使用层5、固化的高热量和压力下在一釜复合夹层(见图。

图1(a))的一段时间内,通常要用几个小时6、综合工件,修剪,及后加工的几何特征7、检查8、紧固或其它结构粘接Figure 1.当然,不是每个复合体系和生产的部分要求都满足所有上述劳动、时间和能源密集的工序,但也更具挑战性的应用,特别是在减轻重量和性能方面,如与航空部件的驱动因素。

事实证明,主要由复合材料所制成的手上篮和高压灭菌是由业内人士和专家参照最近的工业期刊航天制造[4] [5] [6]几篇文章证明确认。

至于巩固和固化复合材料部件,这是本文探讨的重点,一个作者竟然说“消除高压是'复合材料制造商所面临的问题。

本文介绍了一种全新的,正在申请专利[7]对于巩固和固化形成热固性复合材料层压板,其中涉及压紧橡胶模具的过程,并演示了一个完整使用简单二维(平面)模具的几何形状的过程。

这个过程中,将被称为“热固化”,比传统的灭菌可以大大降低成本,能源和相关的时间与固化复合材料。

在此之前的热固性复合材料的巩固和固化将讨论在第二部分。

背景在固化过程开始一方或半固化片使热固性复合材料部件通常是真空袋装去除空气,称为合并或减瘤前。

由材料制造商建议巩固和固化真空袋装复合材料层压板的最常用方法是使用高压蒸气:一个压力容器,允许同时适用于真空袋装的一部分,适用于外部压力的袋子外面提供更高的压差,提高并保持层压板的温度[9]。

惰性气体(通常是氮气)是用在高压灭菌器,以防止氧化和爆炸的组件。

一个典型的真空和压力信息釜温度循环图所示。

1(b)项。

与灭菌的复合材料行业一致,一些研究和开发工作已经消除该反应釜流程步骤,例如使用基体材料,其中暴露在紫外线辐射,重点突出[10],电子束,γ射线,和微波[11]。

然而,更实用的方法是替代复合材料固化过程解决当前行业需要开发热固性基体材料的工作已经上市。

一种可以替代的灭菌是“预浸热压成型”预浸热压是放在成型模中,再打开位置匹配模腔,并通过使阳极和阴极的模具,模具是半封闭的共同施压为进一步巩固预浸热压。

后一部分已治愈,模具半分开,部分被删除。

布莱克莫尔[12] [13]发明了一种固化复合材料部件,其中包含每个模具半导电层,它提供了固化预浸复合材料部件电阻加热压缩成型系统。

模具必须构建一个具有类似的扩张和收缩系数的材料,为压力和温度提供保证。

管状热固性,复合材料部件,如网球拍,需要通过囊状包装周围的预浸料,放入加热的“抓式挖土机”模具的装配,并施压,迫使囊状复合模具表面内部加压直至成型[9]。

这就是所谓的“紧压成型”这消除了需要一个单一的热流体循环水槽的必要,与囊状成型正好相反巩固和固化热固性复合管部分使用来自外部的压力液体。

一个由专家[14]讨论了很长时间的环形专利囊状型内压圆柱形容器。

预浸复合材料部件将插入,两端封闭,加热加压流体通过囊状信封循环的复合材料零件来完成它。

在温度急剧变化,实现了流体控制系统,可以在三个大型储罐液维持不同的温度范围。

这消除了需要一个单一的热流体循环水槽的问题。

与格雷厄姆[15]发明的一种固化复合材料非常相似,[14]仪器和方法。

使用这种方法,首先是一个半固化片层压形成了一薄壁工具(金属或复合),使零件成形和释放涂层,真空袋装类似高压灭菌。

然后夹在灵活的隔膜,加热和加压的有机热载体(导热油)提供隔膜夹层落后于真空层压板和半固化片袋装工具相对较低的压力下,成功完成了后者。

上述可振动膜片导热油,真空绘制在固化周期中被删除。

该技术在商业上可通过科技有限公司[16]。

肯普[17]专利这个过程被称为“固定量被困橡胶成型”那里的热橡胶模具是局限于一个固定的体积热膨胀压力热提供所需的巩固和热固性复合材料层压板完成的一部分。

热紧压固化如前所述,按热固化过程和一个三维(3D)先进的匹配模具刚性模具加热(称为固化模具)和匹配的橡胶模面组成复合材料层板(称为一个带有橡胶面具基地模具)。

这个过程与现有技术不同,此过程的优势将在后文讨论。

完整的模具开发和冲压工艺 - 包括模具设计和制造及具体的制造步骤 - 图所示2,在本节描述。

应该指出的是图 2,只显示为清晰二维的形状,而实际的过程是复杂的三维形状。

Figure 2.A、注射模设计。

模具的热固化过程中设置和按设计要求对固化时间作为一个综合系统中使用(光纤+矩阵),类似的例子在图所示的函数温度,时间,压力,真空规格。

1(b)项。

固化模具表面具有零件的模具侧面形状和抛光和密封。

采用有限元分析(FEA)与特定硬度橡胶硫化模具之间的面具/部分和底座模具压制(在固化温度)模型必须创建一套综合的模具。

该形状和厚度的橡胶分布几何组合(表示为T(s)在图。

2,其中S是一个模具表面上的基地位置)合成的有限元分析模拟(如Nastran软件/ Patran的)和优化算法(外部计算机程序与有限元分析的综合)产生均匀的静水压力时层压橡胶模具硫化模具完全压缩到所需的复合材料在固化温度。

橡胶厚度是通过改变基模,铸造如上所述在介乎基模具和硫化模具在固定的位置形成了一套差距橡胶形状。

这个文件的算法细节没有讨论。

压缩的橡胶面具模仿均匀的压力从高压釜的压力。

基模的形状是建立在计算机辅助设计(CAD)的三维曲面拟合(如非均匀有理基础样条(NURBS)),以有限元分析合成的形状。

橡胶面具的形状和厚度分布是指由基模具和硫化模具的形状由一个特定的距离分开。

额外的几何体在基模需要包括注入之间的基础和固化形成的腔模具浇注料橡胶,以便对登记的橡胶面具造型特征和战略位置。

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