新型国家标准件零件CAD库建立

本文介绍了一种新型的国家标准件零件CAD库，具体描述了其系统结构、数据结构和主要的实现技术。该系统融合了数据库和计算机辅助设计等多种技术，具有灵活的输入手段，自行建立本部门常用零件库的能力和友好的人机界面，实现了机械设计过程中快速查阅零件参数、自动生成零件各向视图的二维图形和三维模型，提高了设计工作的质量和效率。     

Microwave CAD in the year 2010—A panel discussion

The state of microwave CAD in the year 2010 has been projected by a group of 10 experts in the field through a panel discussion conducted via E mail. Advances in CAD capability will be made possible by advances in computing power, both in hardware and in software, and this growth in computing power is expected to continue through the next decade at least. This increased computing power will create two types of improvement in microwave CAD. Quantitative improvements will occur in areas that are being done now but in a very limited way, and qualitative improvements will occur when things that are not now being done are possible. The next step in this panel‐discussion process is discussed. ©1999 John Wiley & Sons, Inc. Int J RF and Microwave CAE 9: 439–448, 1999.     

基于实例推理的冲模智能CAD系统关键技术的研究

本文以三维软件(SolidWorks)为平台,对基于实例推理的智能冲模CAD系统关键技术进行了研究。讨论了冲模建模及参数化实现、实例库的建立、实例的检索和存储、实例的评价和修改的方法。     

从微机排版角度来探讨修订校对符号标准的可能性

本文探讨修订现行国家校对符号标准的可能性，以期更适应微机编辑排版形势的需要．     

协同CAD设计中基于设计历史的冲突检测算法

多位设计者并发地对特征进行操作,具有同步性、分布性和无约束性的特点。并发控制的基本目标就是通过对各用户的操作进行限制,规范化设计时序,保持设计工作的顺利进行。与文字、图像等数据的并发控制相比,CAD特征之间各种复杂的关系（如特征的空间关系、依赖关系等）,使得基于特征的并发控制十分困难。对CAD特征之间各种复杂关系对协同并发操作的影响进行详细分析,并给出复制式协同环境下并发冲突的检测方法和解决方案。     

以职业能力需求为导向的高职《电子CAD》课程改革

高职《电子CAD》 课程的教学效果直接影响应用电子技术专业毕业生的职业能力.课程改革以职业能力需求为导向,以项目化教学为模式,以学生训练为主,教师讲解和指导为辅,技能目标覆盖大部分直接就业和部分进阶岗位的职业能力要求.文章对教学项目选取和实施作了重点阐述,对同类课程的改革有一定的参考意义.     

Bounds for the solution of the Lyapunov matrix equation — A unified approach

In recent years, several bounds have been reported for the solution of the continuous and the discrete Lyapunov equations. Using the unified Lyapunov equation, we give in this paper bounds for the solution of this equation. In the limiting cases, the bounds reduce to existing bounds for both the continuous and discrete Lyapunov equations.     

Rate-interval curves — A tool for the analysis and monitoring of network traffic

In this paper we propose a method, related to the theory of Network Calculus, for the analysis of aggregate network traffic by means of empirical rate-interval curves obtained from experimental data. The algorithm on which it is based differs from the commonly employed wavelet-based approach, although it retains some of its multiresolution features. We briefly introduce the theoretical aspects, analyze measurement accuracy and present results, obtained both by simulation and by the analysis of real traffic traces, which provide an assessment of the strengths and weaknesses of the proposed method.

Rate-interval curve analysis provides very robust and acceptably accurate estimates of the Hurst parameter value and, even in the presence of flow irregularities, results can be proved to be correct as far as scaling properties are concerned.

Further analyzes concerning peaks, bursts and similar localized phenomena that may have a significant impact on the performances of a network are allowed by considering maximal rate envelopes, showing the potential of this approach for monitoring applications.     

One-pass compilation at its limits — A modula-2 compiler for the xerox dragon computer

We present conceptual and implementation aspects of a one-pass Modula-2 compiler that was developed by Xerox PARC's future Dragon workstation. Dragon features several architectural innovations. Among them are a reduced instruction set and a stack of fast registers used to store local data. This paper emphasizes problems and solutions connected with one-pass compilation. Although a little out of fashion at present, this simple method, if appropriately applied, turns out to be surprisingly powerful.     

Designating “hot” items in multiple‐choice questions—A strategy for reviewing course materials

Suppose learners use their free time to go online to review course materials, and they do so by taking optional tests that consist of multiple‐choice questions (MCQs). What will happen if, for every practice question, there is always a choice (out of four possible choices) that is marked as “the (current) hot choice?” Will this make any difference in learning effects? To answer this question, an educational experiment was conducted. It was found that “hot designations” helped the experimental group perform significantly better in both the immediate post‐test exam and a delayed post‐test exam and that learners with higher levels of initial knowledge benefited more from this review strategy. From the results of a follow‐up questionnaire and one‐on‐one interviews, it was found that the proposed review strategy promoted a more thorough thinking style in subjects of the experimental group.     

MESHMdl event spaces — A coordination middleware for self-organizing applications in ad hoc networks

Mobile ad hoc networks (MANETs) are gaining importance as a promising technology for flexible, proximity-based, mobile communication. However, the inherent dynamics of MANETs imposes strong limitations on the design of distributed applications. They need to be able to adapt to changing conditions quickly and organize themselves in terms of component placement and communication habits. In this paper, we present MESHMdl, a middleware that provides a high level of awareness and decoupling for application components to make them more flexible and adaptable. We focus on the Event Space as the central communication medium of MESHMdl. The Event Space offers a simple, unified communication interface for inter-agent communication as well as for communication with the middleware and resource access. Furthermore, it serves as a means for flexibly extending a MESHMdl daemon. We investigate the performance of the Event Space on different mobile devices and show that it is superior to comparable systems.     

Wang laboratories' VLSI design strategy or Putting blinders on your engineers keeps your horse in the race

The article discusses the rationale used to make the decision to implement a constrained design capability for VLSI in Wang. A CAD/CAM system will be put in place that will permit product designers to achieve design and manufacturing turn-a-round times that are consistent with a product development cycle of 18 to 24 months. The functional requirements of the various subsystems are discussed as well as those for the excutive, the data base, and the audit capability. The latter capabilities are necessary to achieve a controlled constrained design environment.     

The main features of BAHUS — biometeorological system for messages on the occurrence of diseases in fruits and vines

Recently, there has been an increasing demand for providing a high level of production of wholesome plant food but without losing its quality from the consumer's point of view. In this regard, it is required to provide reliable information about the occurrence of plant diseases so as to ensure their efficient control. The reliability of this information increases substantially if both the meteorological and the biological quantities, measured or modelled, are properly integrated in a prognostic system. By the joint efforts of the authors' institutions the biometeorological system BAHUS for messages on the occurrence of the most important diseases in fruits and vines has been developed. This system has been developed in Microsoft FoxPro 2.6(X) following standards of analysis of a large amount of data. It consists of two modules. The first provides input for prediction in the form of the measured or modelled meteorological and biological data, while the second, on the basis of available input data, selects the corresponding method for messages on the occurrence of disease. Depending on the method selected, the meteorological data can be assimilated either from weather stations, atmospheric models or software packages LAPS (land–air parameterization schemes providing 10 min prognostic values) and KARLOS (providing their climatological values) integrated in the system as a whole. The BAHUS has been designed as an open system giving a wide range of possibilities for increasing its level of sophistication.     

Borehole Optimisation System (BOS)—A GIS based risk analysis tool for optimising the use of urban groundwater

Urban groundwater is generally an underused resource, partially due to the perceived risk of pollution and the strategic difficulties in placing boreholes in built-up areas. The development of a probabilistic risk based management tool that predicts groundwater quality at potential new urban boreholes is beneficial in determining the best sites for future resource development. The Borehole Optimisation System (BOS) is a custom Geographic Information System (GIS) application that has been developed in the ArcView 3.1 environment with the objective of locating the optimum locations for new boreholes in urban areas. It couples three component models, the Catchment Zone Probability Model (CZPM), the Land-use Model (LM) and the Pollution Risk Model (PRM). The CZPM produces probabilistic catchment zones for a user-defined abstraction borehole location under uncertain and variable hydrogeological parameters. The LM identifies current and historical industries located within the selected probabilistic catchment zone. The PRM uses these industrial and the associated hydrogeological and contaminant data to predict probabilistic contaminant concentrations in a particular analysis year. This paper outlines the methodologies employed in the development of BOS and attempts to validate the approach by presenting a simulation that forecasts PCE concentrations at an actual borehole location in the Nottingham urban aquifer. The results predict contaminant levels in the abstracted water that are in agreement with observed values, both being above the UK Drinking Water Standard of 10 μg/l. These demonstrate the applicability of BOS as a tool for informing decision-makers on the development of urban groundwater resources.     

A novel full‐wave CAD for the design of tapered leaky‐wave antennas in hybrid waveguide printed‐circuit technology

This work presents a novel computer‐aided design (CAD) tool for the design of tapered leaky‐wave antennas (LWAs) in hybrid waveguide printed‐circuit technology. The software package is composed of several tools, which are connected together to provide a semi‐automated step‐by‐step design procedure. The design procedure is presented and the different tools are described, together with the involved theory, leading to the design of tapered LWAs. A practical taper design is performed, and comparisons with simulations using commercial software (HFSS) are presented for validation purposes. Due to the full‐wave nature of the technique used in the analysis engine, excellent agreement is shown between the proposed 2D‐based approach, and 3D HFSS results. Also, the analysis procedure is fast, thus leading to semi‐automated designs that are not affordable with common 3D optimization techniques. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.     

Using MERIS full resolution data to monitor coastal waters — A case study from Himmerfjärden, a fjord-like bay in the northwestern Baltic Sea

In this paper we investigate if MERIS full resolution (FR) data (300 m) is sufficient to monitor changes in optical constituents in Himmerfjärden, a fjord-like, north–south facing bay of about 30 km length and 4 km width. The MERIS FR products were derived using a coastal processor (FUB Case-2 Plug-In). We also compared the performance between FUB and standard processor (MEGS 7.4), using reduced resolution (RR) data (1 km resolution) from the open Baltic Sea, and compared the products to sea-truthing data. The optical variables measured for sea-truthing were chlorophyll, suspended particulate matter (SPM), as well as coloured dissolved organic matter (CDOM, also termed yellow substances), and the spectral diffuse attenuation coefficient, K_d(490). The comparison of the RR data to the sea-truthing data showed that, in the open Baltic Sea, the MERIS standard processor overestimated chlorophyll by about 59%, and SPM by about 28%, and underestimated yellow substance by about 81%, whereas the FUB processor underestimated SPM by about 60%, CDOM by about 78%, and chlorophyll a by about 56%. The FUB processor showed a relatively high precision for all optical components (standard deviation: 6–18%), whereas the precision for the MEGS 7.4 was rather low (standard deviation: 43–73%), except for CDOM (standard deviation: 13%). The analysis of the FR data showed that all FR level 2 water products derived from MERIS followed a polynomial decline in concentration when moving off-shore. The distribution of chlorophyll and SPM was best described by a 2nd order polynomial, and the distribution of CDOM by a 3rd order polynomial, verifying the diffusional model described in Kratzer and Tett [Kratzer, S. and Tett, P. (in press). Using bio-optics to investigate the extent of coastal waters — a Swedish case study. Hydrobiologia.]. A new K_d(490) and Secchi depth algorithm based on MERIS channel 3 (490 nm) and channel 6 (620 nm) each was derived from radiometric sea-truthing data (TACCS, Satlantic). Applying the K_d(490) algorithm to the MERIS FR data over Himmerfjärden, and comparing to sea-truthing data the results showed a strong correlation (r = 0.94). When comparing the FR data to the sea-truthing data CDOM and K_d(490) showed a low accuracy, but a high precision with a rather constant off-set. In summary, one may state that the precision of MERIS data improves by applying the FUB Case-2 processor and the accuracy improves with improved spatial resolution for chlorophyll and SPM. Furthermore, the FUB processor can be used off-the-shelf for open Baltic Sea monitoring, provided one corrects for the respective off-set from sea-truthing data which is most likely caused by an inaccuracy in the atmospheric correction. Additionally, the FR data can be used to derive CDOM, K_d(490) and Secchi depth in Himmmerfjärden if one corrects for the respective off-set. We will need to perform more comparisons between sea-truthing and MERIS FR data before the new K_d(490) algorithm can be made operational, including also scenes from other times of year. In order to provide a level 2 product that can be used reliably by the Baltic Sea user community, our recommendation to ESA is to include the spectral attenuation coefficient as a MERIS standard product.     

Experimental insight into the temperature effects on DC and microwave characteristics for a GaAs pHEMT in multilayer 3‐D MMIC technology

This paper is focused on studying the behavior of a GaAs pseudomorphic high electron mobility transistors (pHEMT) with respect to the temperature. The tested pHEMT is realized using the multilayer three‐dimensional (3‐D) monolithic microwave integrated circuit (MMIC) technology. The analysis is based on temperature‐dependent on‐wafer measurements carried out from 298 K to 373 K. The experiments consist of DC characteristics and scattering parameters in the broad frequency range from 45 MHz to 40 GHz. The effect of the temperature on the measured transistor performance is analyzed in detail and then, to gain a better insight and understanding of the device behavior, the achieved measurements are used for extraction and validation of a small‐signal equivalent‐circuit model for different temperature conditions. This study shows that, by heating the studied device, the observed performance variations depend remarkably on the selected bias condition. In particular, the output current and transconductance are degraded at higher gate‐source voltage and improved as the transistor is driven towards the pinch‐off. This is due to the counterbalancing of temperature‐dependent effects contributing in opposite ways to the resultant behavior of the transistor. Therefore, depending on the given application, an appropriate selection of the bias and temperature conditions is essential to guarantee adequate transistor performance.     

The users' perspective on how creativity techniques help in the idea generation process—A repertory grid study

Despite the large number of available creativity techniques such as Brainstorming and Six Thinking Hats and their widespread use in idea generation workshops, it remains unclear what specific aspects creativity technique users perceive as helpful. We conducted five large‐scale product development workshops with 216 inexperienced students in groups of four to six people and personally interviewed a subset of 87 participants using the repertory grid procedure. The results reveal a framework of facilitating and impeding factors users associate with the methodological frame, the process view and anticipated idea characteristics of creativity techniques. Particularly helpful and differentiating factors cover visual, cognitive and emotional processing systems. In addition, we evaluate 11 commonly used creativity techniques and present underlying reasons for why some of them are perceived as more helpful than others by inexperienced users. The results thus provide a stepping stone to understand the users' perspective on creativity techniques, improve existing techniques and develop better versions of them.