印制电路板CAD／CAPP／CAM一体化实现

本文介绍了实现印制电路板ＣＡＤ／ＣＡＰＰ／ＣＡＭ一体化所作的工作，重点解决了数控钻孔文件向没有通信接口的ＥＸＣＥＬＬＯＮ２００数控钻床的传输问题，制定了印刷电路板ＣＡＤ／ＣＡＰＰ／ＣＡＭ的有关规定，印刷电路板ＣＡＤ／ＣＡＰＰ／ＣＡＭ一体化的建立，极大地提高了印刷电路板生产的效率和质量。     

产品数据表达与交换标准STEP及其集成技术

本文简述并分析了产品数据表达与交换标准ＳＴＥＰ的形成过程、体系结构、ＥＸＰＲＥＳＳ语言构造及其产品数据建模，并针对ＣＡＤ、ＣＡＰＰ、ＣＡＭ各个系统间的数据交换需求介绍了两种集成技术及其实现方法     

低信噪比信号下A／D量化的影响分析

本文为了对低信噪比信号Ａ／Ｄ的影响进行分析，提出了一种分析Ａ／Ｄ影响的分析方法，由此可以分析信噪比情况下Ａ／Ｄ量化后噪比的损失。给出了信噪比一定的条件下Ａ／Ｄ量化电平和信噪比损失曲线。     

异步DS／CDMA系统中横向均衡器的性能分析

文章研究了在异步直扩码分多址（ＤＳ／ＣＤＭＡ）系统中横向均衡器对多址干扰的抑制能力,讨论了在不同情况下的稳态解,得到的解析式比文献（３）（４）更简单。实验仿真表明横向均衡器在异步情况下没有同步时的性能好,但远好于匹配滤波器,能很好地抑制多址干扰。     

EME′2000征文通知

中国电子学会电子机械工程分会第四届学术年会（ＥＭＥ′２０００）将于２０００年１０月在桂林市举行。会议由电子机械工程分会主办、桂林电子工业学院承办、广西电子机械学会协办。会议将在机电一体化技术、电子电路表面组装技术（ＳＭＴ）、电子产品ＣＡＤ／ＣＡＰＰ／ＣＡＭ、电子产品现代设计和系统集成技术、电子产品柔性制造和虚拟制造技术、电子产品全寿命周期管理及其ＣＡＬＳ（持续采办和全寿命周期支援）、机器人、微机械与微机械加工等先进制造技术领域;以及在电子设备分机设计、布线与电气互连、热分析与设计、振动与冲击、电…     

网格编码MQAM直扩多址系统的性能分析

本文将非恒包络高效网格编码调制ＴＣ－ＭＱＡＭ应用于瑞利慢衰落信道下的直接序列扩频多址系统中。针对衰落信道和ＴＣ－ＭＱＡＭ的特点，提出了一种分析ＴＣ－ＭＱＡＭ用于衰落信道下ＤＳ／ＳＳＭＡ系统性能的方法，数值模拟表明在系统用户数、用户信源比特速率以及码相同的条件下，本文所构造的非恒包络１／４ＴＣ－１６ＱＡＭ性能优于同状态数３／４ＴＣ－１６ＱＡＭ和恒包络２／３ＴＣ－８ＰＳＫ。这说明通过增大最小分支数等适     

数字音频广播

９２年４月开路展示了欧洲尤里卡１４７计划的数字音频广播（ＤＡＢ）成果，宣告了ＤＡＢ的诞生，各国竞相试验研究实施的方式，国际标准化组织也积极开展ＤＡＢ标准的研究，全世界进入了ＤＡＢ时代。在频带选用方面，有欧洲的宽带新频段方式和美国在现有ＦＭ／ＡＭ频带内的方式；编码调制方面有欧洲的ＭＵＳＩＣＡＭ加ＣＯＦＤＭ和美国的ＡＴ＆Ｔ（或ＭＵＳＩＣＡＭ）加多频四相调制等。９４年美国ＥＩＡ和ＮＲＳＣ对其国内包括新频段和带内方式的六种（五种是地面广播）候选方式进行测试比较后，提出美国ＤＡＢ的标准建议。这将对各国选定ＤＡＢ方式有重要意义．     

软件无线电在我国第三代移动通信系统中的应用

本文首先回顾第三代移动通信系统的研究动态，并着重对我国提出的Ｓ－ＣＤＭＡ系统进行分析比较。得出软件无线电技术是确立我国第三代移动通信系统的关键技术之一。本文还提到Ｓ－ＣＤＭＡ采用软件无线电后新开辟的测向定位功能。     

“CDMA蜂窝移动通信系统高级技术研讨会”在京召开

“ＣＤＭＡ蜂窝移动通信系统高级技术研讨会”在京召开中国电子学会通信分会专家咨询委员会于１９９６年１０月１５日在北京科技会堂召开了“ＣＤＭＡ蜂窝移动通信系统高级技术研讨会”，就ＣＤＭＡ的发展及应用前景进行研讨。电子工业部通信与系统装备司，国家无委会办公...     

耐温抗盐聚合物驱油剂ZYS的合成与评价

用ＡＭＰＳ、ＡＭ、ＤＭＤＡＡＣ、Ｓ型单体（含磺酸基长链烷基两亲表面活性单体）合成了耐温抗盐聚合物驱油剂ＺＹＳ,借助红外光谱研究了单体及共聚物的结构,系统评价了产物ＺＹＳ的驱油性能。结果表明,合成共聚物在总矿化度１．６×１０＾５ｍｇ／Ｌ其中Ｃａ＾２＋、Ｍｇ＾２＋总量为３０００ｍｇ／Ｌ）的人工盐水中具有良好化学稳定性,经９０℃、１８０ｄ老化后仍有保持较高粘度。     

UGⅡCAD／CAM软件应用研究

本文对Unigraphics(简称UGⅡ）CAD／CAM软件在钣金件中的应用进行了论证，包括钣金件的三维实体造型、自动展开、自动编程与后置处理等。介绍了AMADA数控冲床专用后置处理程序的开发、调试和数控加工试验验证，并在此基础上总结出钣金件数控加工工艺路线。     

电子装备设计制造一体化技术综述

本文介绍了先进制造技术的发展方向之一－－设计制造一体化技术的产生背景、市场需求、概念、关键技术以及在电子产品行业中应用的主要方向。     

毫米波平板隙缝阵天线工艺设计与制造

毫米波平板隙缝阵天线具有增益高、副瓣低、体积小和质量轻等优点,是毫米波雷达的关键设备。针对其多层、空腔、薄壁的复杂结构特点和加工精度高、封装性好的工艺要求,结合集成工艺设计,应用CAD/CAM一体化技术和精密连接技术,实现了天线的高技战术性能要求。     

Attitudes towards computer technology: comparison of retail buyers and apparel manufacturers in the U.S.A.

Apparel retailers and manufacturers are incorporating advanced technologies such as CAD/CAM systems and electronic data interchange into their businesses. Attitudes held by key personnel toward these new technologies can enhance or hinder implementation. This study was designed to investigate and compare the attitudes of manufacturers and buyers towards computer technology. Fifteen Likert-type attitude statements were developed by the researchers. A pilot test of the instrument resulted in minor changes. A total of 105 usable questionnaires were returned: 57 from manufacturers and 48 from retail buyers. t-test results indicated that buyers' and manufacturers' attitudes differed significantly on five of the 15 attitude statements. A discriminant analysis showed that the same five statements significantly discriminated buyers from manufacturers. Manufacturers' responses were more positive than buyers' on four of these statements. Overall, the results indicated that apparel manufacturers and retail buyers held favourable attitudes towards computer technology.     

Attitudes of Louisiana apparel manufacturers towards computer technology

Current literature has suggested that there is a reluctance on the part of the domestic apparel industry to adopt advanced computer technology. This study was designed to investigate the attitudes of Louisiana apparel manufacturers towards computer technology. An attitude questionnaire was mailed to all identified apparel manufacturers in the state. The results indicated that the apparel industry in the state of Louisiana is comprised of many small, privately owned companies. A large array of products in a variety of size ranges is produced in the state. Statistical analyses indicated that there were some differences between attitudes of apparel manufacturers and contractors. In general, contractors were not as aware of the availability and transferability of advanced technology for the apparel industry as manufacturers. Manufacturers and contractors who had some formal training with CAD/CAM systems had more positive attitudes toward the competitiveness of the industry with imported products. It is recommended that the apparel industry in the state explore the technological options available to modernize for a more competitive future.     

高性能K波段宽频带检波器

介绍了高性能的宽带检波器的CAD设计方法及测试结果。该检波器采用波导E面集成电路形式 ,通过对极鳍线实现波导微带过渡 ,采用高频电磁场仿真软件和微波电路CAD软件完成该检波器的设计。测试结果表明 ,该设计方法实现的检波器具有优良的性能     

Communication Costs and the Boundaries of the Firm

Much has been written about where the boundaries of the firm are drawn, but little about what occurs at the boundaries themselves. When a firm subcontracts, does it inform its suppliers fully of what it requires, or is it willing to accept what they have available? In practice firms often engage in a dialogue, or conversation, with their suppliers, in which at first they set out their general requirements, and only when the supplier reports back on how these can be met are their more specific requirements set out. This paper models such conversations as a rational response to communication costs. The model is used to examine the impact of new information technology, such as CAD/CAM, on the conduct of subcontracting. It can also be used to examine its impact on the marketing activities of firms. The technique of analysis, which is based on the economic theory of teams, has more general applications too. It can be used to model all the forms of dialogue involved in the processes of coordination both within and between firms.     

微带压控振荡器设计与仿真

介绍了S波段微带压控振荡器的设计方法,并使用微波仿真软件Serenade8.5对振荡器进行仿真分析,给出了仿真和实际电路的结果。     

MATLAB在控制系统仿真中的应用

本文简述了采用MATLAB软件的控制工具箱对控制系统进行辅助设计的一般方法。MATLAB具有编程简单直观，用户界面友善，开放性强等优点，能有效提高控制系统的工作效率，是控制系统中一种很好的工具。