某密闭机箱结构设计与热仿真分析

根据某型雷达模拟器的机箱对于质量轻、体积小、方便携带、防雨、防尘等结构和散热方面的实际使用需求,提出一种紧凑密闭型机箱结构设计布局的方案,整机尺寸为380 mm×160 mm×280 mm,箱体质量6.5 kg;采用一种自然散热、均温板导热、外部强制风冷散热的组合散热方案,并优化布置自然散热和强制风冷散热器件布局,合理布置散热齿和确定风机型号.设计完成后,用FloEFD软件对机箱使用环境进行热仿真分析,分析结果显示,机箱表面的最高温度为81.72℃,低于许用温度105℃,印制板上芯片表面的最高温度为76.25℃,低于许用温度85℃,满足器件的使用条件.产品制造完成后,进行相关环境试验,相关试验和电性能测试均通过验证,说明该方案设计合理有效,满足了机箱在尺寸、质量、密闭性、散热性上的使用要求.     

非等高翅片平板热管散热器仿真研究与优化设计

为提高热管散热器的散热效率,文中对平板热管散热器的散热翅片进行优化,提出一种在风冷条件下的非等长翅片散热器。首先通过研究环境温度、热源功率、风速对芯片温度的影响,当风速大于8 m/s时,通过增大风速对芯片的降温作用并不显著。然后通过对比等长翅片与非等长翅片的散热效率,提出非等长翅片中最长翅片与最短翅片差p的概念,p值分别取8.5 mm、17.0 mm、25.5 mm、34.0 mm进行仿真对比研究。当热源功率为600～1000 W,平板热管散热器翅片长度差在25 mm左右,散热效率最高;当热源功率为200～400 W,平板热管散热器翅片长度差在8.5 mm左右时,散热效率最高。结果表明,非等长翅片热管散热器优于等长翅片热管散热器的散热效率。     

某机载毫米波雷达天线仿真热设计

针对某型机载毫米波雷达天线热设计难题,提出了热管结合强迫风冷的新型冷却方式,设计了专用风道。应用数值模拟方法首先对T/R组件进行了热仿真计算,其次对天线背部风机抽风、吹风进行了仿真比较,再对散热翅片和风量分配进行了仿真优化,最后对3 km高空状态进行了仿真计算。计算结果表明,天线背部风机吹风明显好于抽风;翅片厚度0.8 mm,翅片数134,占空比23.8%的翅片结构散热较好;限流板阻力系数为5时风量分配较均匀;高空环境下满足天线工作要求。该方式合理可行,满足系统热设计要求,为同类产品的热设计提供了重要参考。     

雷达电子机箱的热分析及优化设计

雷达电子机箱热控性能的好坏直接影响其工作性能与寿命。某型号雷达的机箱由于使用环境改变,使用条件限制,无法采用原来的强迫风冷方式冷却,因此,需对机箱冷却方式做变更。对该型号雷达机箱热控做优化改进方案,确定了在局部热点区域采用热管(均温板)提高热传导能力、将机箱壳体与散热翅片材料更换为导热性能更高的铝材、优化散热翅片参数的优化设计方法,确保优化后的冷却方案满足雷达电子机箱的热设计指标要求。     

高功率LED太阳花式热沉的散热模拟与验证

基于传热理论,研究LED工矿灯冷却模块在自然对流下的散热性能。以降低芯片结温为目的并保证芯片结温在允许范围内,通过数值仿真对太阳花式热沉的结构进行优化。采用控制变量法分析翅片厚度、翅片个数、翅片高度以及空心圆柱厚度对散热的影响。研究结果表明:当太阳花式热沉的翅片厚度为1.2mm,翅片个数为53,翅片高度为62.5mm,空心圆柱厚度为1.5mm时达到最佳散热效果,且仿真结果与实验数据基本一致,验证了该优化方案的可行性。     

某光控相控阵雷达组件热设计与参数优化

为了确保光控相控阵雷达中微波发射前端组件运行的稳定,为高热流密度功放组件提供合理的温度环境,依据集成系统的结构与前端输入,提出了匹配系统的热设计方案,并采用仿真软件进行了模拟与分析。结果表明,系统最高温度不超过指标温度,且热均匀性较高。该热设计方案验证了采用金刚石/铜进行热扩展并结合合理的液冷冷板结构,可以实现紧凑高效的散热需求。此外,提出了多级翅片与对插式辅助翅片的结构优化方案,并分析了相关参数对散热的影响。该系列热设计方案与参数分析可以为雷达高热流密度组件的热设计提供思路。     

大功率隧道照明LED散热模拟及优化设计

翅片散热器是大功率隧道LED常用的散热形式,合理的设计翅片结构,对延长LED寿命、节约散热器成本、减小散热器重量至关重要。通过ANSYS WORKBENCH对影响翅片散热器的两个重要因素,翅片高度和厚度进行了分析,实验发现芯片最高温度随着翅片的厚度和高度增加而减小,14个芯片温度的均匀性随着翅片的厚度和高度增加而增强。通过多目标遗传优化算法对翅片进行优化设计,既降低了芯片温度,又减小了翅片散热器用材和重量,这对于解决LED翅片散热问题具有重要的工程意义。     

基于ICEPAK仿真的散热器结构热设计研究

文中利用ICEPAK软件对多密度高功率芯片散热器结构进行了热设计研究。研究确立了影响翅片散热器散热性能的关键尺寸设计参数,如基板厚度、翅片高度、翅片厚度和翅片间距等,并得出了各尺寸设计参数对其散热效果的影响趋势,确定了散热器结构的最佳布局方案。此外,研究还建立了最佳布局的散热器结构实物并进行了高低温试验以模拟其高温散热情况。通过实验数据对比发现,仿真计算结果与实际较为吻合,进而验证了ICEPAK软件在电子设备散热设计方面的准确性与可靠性。     

锯齿形翅片散热器风冷性能试验研究

文中从试验的角度研究了锯齿形翅片散热器的风冷性能。锯齿形翅片散热器具有结构复杂、不易仿真实施的特点。文中系统介绍了锯齿形风冷散热器的典型结构形式以及风冷性能测试系统原理、性能和测试分析结果,从试验实测的角度研究了锯齿形翅片散热器的应用选型及其与散热量、风量、风压等的关系,分析了翅片参数(翅高、翅宽、翅片节距)对散热性能的影响,对电子产品散热的风冷设计具有较高的参考价值。     

高热流密度功率器件热设计及实验研究

雷达系统中的DAM模块发热量大,热流密度高,其散热性能直接影响功率器件运行的可靠性。对从功率器件到散热器之间的传热路径以及散热器风道侧参数进行优化设计,确定在热源上焊接铜板以降低热流密度、选择导热性能优异的界面接触材料、冷板局部焊接铜板以减小平面方向温度梯度、增加散热器翅片高度和加密散热器翅片排布等优化设计方法改进常规风冷散热方案,并对优化后的风冷散热方案进行实验研究,实验结果与仿真结果相吻合,验证了风冷散热优化方案的可行性。     

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...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

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.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

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.     

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....