基于遗传算法的表面组装电子元件热布局优化

基于热叠加模型,选取表面组装电子元件的平均温度作为评价指标,确定出用于热布局优化的适应度函数,基于遗传算法提出了一种电子元件热布局优化算法,并编制相应优化程序,实现了对电子元件的热布局优化;利用有限元软件ANSYS结合具体实例对优化结果进行仿真验证,验证结果表明优化结果与仿真结果基本一致,由此验证了热布局优化程序的有效性;根据优化结果得出热布局规则：各大功率电子元件分散开,并分布于板级电路四周,各小功率电子元件围绕大功率电子元件分布于中心,并按一定规律排列.     

电子元件自动分选系统的研究与设计

以电子元件自动分选系统为研究对象，针对取物机械手提出了一种基于模糊控制理论的控制方法，充分利用了模糊推理和传统控制方法的优点，具有很强的实用性。目前已成功应用于某电子元件自动分选系统的设计中，并取得了良好的效果。     

美国《设计新闻》调查美国工业产品设计采用电子技术的情况

一、对产品设计师在产品设计中采用元件的调查 被调查的设计师中有92.2％在其设计中使用电子元件,不使用电子元件的占7.7％。 二、对准备在产品设计中扩大电子元件应用的调查 82.2％的设计师计划在产品设计中扩大应用电     

2009中国市场电子元器件领军厂商评选胜利完成

2009年10月20日，中国电子展组委会和中国电子商情杂志社联手电子元件技术网（WWW．cntronics．com）共同举办的2009中国电子元器件领军厂商与服务商评选胜利完成，将于2009年11月11日在上海浦东新国际展览中心举办盛大的颁奖和展示活动。这次行业调查是中国电子展的重要活动，电子元件技术网携手中国电子商情杂志组织和实施了这次调查。工业和信息化部、商务部、中国电子学会、中国电子元件协会和中国电子企业协会等给予这次行业调查大力支持。     

自动拆卸电路板电子元件装置的设计

物理机械法对废弃印刷电路板上的电子元件实现自动拆卸是现在废弃电路板处理技术的发展趋势.本文针对已有的螺旋拆卸装置对电子元件拆除破坏性较大、拆除率不高等缺点,设计了一种带有通过式连续加热炉的自动拆卸设备,利用带有夹具传送装置和自动入料装置实现自动入料、自动拆卸、自动出料的功能,最后通过试验表明该装置拆卸电路板电子元件高效、可靠、安全,且电子元件损坏率低.     

数控激光指示电子元件半自动插装机

介绍一种数控激光指示的电子元件半自动插装机，概述了该机的工作原理，系统组成，对其控制系统的硬件和软件设计作了必要阐述。     

1992年欧洲光电子元件交易额将达到36亿美元

据Frost & Sullivan公司发表的“欧洲光电子元件”报导,1987年的欧洲光电子元件交易额约17亿美元,1992年将达到36亿美元。在这个研究报告中将所有光电子元件(液晶显示器、等离子显示器、红外探测器、发光二极管、激光二极管和光纤等)都考虑在内。 1987年西德的光电子元件交易额占总数的     

随机振动环境下车用电子元件寿命分析

针对车用电子元件进行随机振动耐久性测试,进而分析车用电子元件接脚在随机振动环境下的寿命,得到电容接脚与电阻接脚的理论计算寿命与试验寿命。针对随机振动环境,提出了延长车用电子元件寿命的两种措施。     

基于PCI总线的含电子元件安全电路试验装置的研究设计

对含电子元件安全电路的试验要求进行了分析,研究设计了一套基于PCI总线的试验装置,该装置能完成GB7588-2003对含电子元件安全电路所要求的所有试验,对整个试验过程进行监控和分析,控制试验的进行,并对样品合格与否做出正确判断。     

贴装性能与外部设计的探究

伴随着电子元件的发展，集成电路(IC)的开发，半导体材料的多元应用，电子科技革命势在必行，这就要求贴装性能(贴片效率和焊接质量)不断提高，以加快适应和满足经济社会对各种电子产品的需求。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.