翅片热板散热器的传热研究

在已设计的翅片热板散热器基础上进行了传热性能实验,对于充装不同工质、工质充装量、翅片热板散热器的工作方式等因素都进行了较深入的传热测试,分析这些因素对翅片热板散热器传热性能的影响.同时对翅片热板散热器的瞬态和稳态传热性能也进行了实验测试,分析了瞬态、稳态表面温度变化曲线,并进行了传热性能比较分析,讨论了工质充装量、倾斜角度等对翅片热板散热器传热性能的影响.     

基于虚拟仪器动态信号测试系统的设计

以PC机、数据采集板为主要硬件,以图形化编程语言DASYLab为软件开发平台．设计了基于虚拟仪器的动态信号测试系统。系统软件主要由数据采集模块、数据处理分析模块和数据库管理模块等构成,文中对各模块的功能进行了详细的介绍。     

均热板散热性能实验研究

均热板作为一种新型的高效散热技术,具有热导率高、均温性良好等优点,越来越多地应用于机载电子设备。文中介绍了均热板散热原理,针对均热板和相同尺寸电子设备模块壳体在不同工况下进行散热性能实验研究,对比测试了两者均温效果和散热效果。测试结果表明,均热板的均温效果优于同尺寸常规铝材模块壳体;功耗及热流密度越大,均热板散热优势越明显;采用不同散热方式,均热板内芯片与模块壳体内芯片的温差相同;多芯片时,总功耗越高芯片表面温度越高,芯片热流密度越集中,芯片表面温度越高。当达到散热极限时,应设计为多芯片,低热流密度的形式,均热板可以达到更好的散热效果。     

直线超声电机特性测试系统的设计及试验

针对现有直线超声电机特性测试系统存在的测试精度低、功能单一和自动化程度低的问题,笔者设计了一种直线超声电机特性测试系统,主要由电机驱动模块、数据采集模块和测试控制及数据处理模块3部分组成。电机驱动模块以STM32F429微控制器为核心,可方便实现对驱动信号的电压、相位以及频率等参数调节;数据采集模块主要由位移传感器、拉压力传感器和高速数据采集卡组成;测试控制数据处理模块主要由PC机实现。利用该系统对一种蝶形直线超声电机的机械特性和瞬态特性进行了测试,结果表明:该系统可很好地实现对直线超声电机的特性测试,而且操作简便,易于扩展。     

均热板散热器的传热特性实验研究

为了研究通信设备不同应用场景中散热器传热性能,设计了内嵌均热板散热器、复合芯均热板散热器和金属丝网吸热芯均热板散热器３种不同类型的散热器,针对不同风速、不同放置方向（重力因素）对３种均热板散热器的传热性能进行了实验研究。实验结果表明,在不考虑重力因素的情况下,复合芯均热板散热器具有较好的传热性能,而放置方向（重力因素）对复合芯均热板散热器和单一粉末烧结吸热芯均热板散热器的传热性能影响较大,在散热器设计选型时需要重点考虑均热板散热器的实际应用场景。     

星载DBF单机热设计

星载DBF单机性能直接影响数字体制相控阵天线的分辨率、波束指向精度等关键指标,其可靠性水平直接关系到整个相控阵系统能否在轨稳定工作.针对某DBF单机的结构和热设计需求,采用与模块壳体一体化的铝制均热板方案,实现了设备的轻量化和传导温差的大幅降低.热仿真分析和热真空测试的结果均表明铝制均热板的应用提升了DBF单机在空间环...     

基于ZigBee协议的矿用设备数据采集分站设计

针对煤矿井下工况环境复杂,数据采集监测系统布线繁琐、功耗大、通信质量不稳定等问题,采用ZigBee无线传感器网络技术与STM32嵌入式系统设计了一种面向矿用设备的数据采集分站。首先对数据采集分站进行了总体方案设计,然后详细介绍了基于ZigBee技术的无线数据采集模块、有线数据采集模块、主控模块与WiFi通信模块的软、硬件设计方法,最后对其通信性能进行测试。结果表明该设计能够有效实现无线以及有线方式的数据采集、模数转换、分析处理、存储显示等功能,在测试范围内具有误包率低、通信质量稳定等特点。     

通用型自动变速器数据采集系统

针对车辆自动变速器控制信号的特点,开发了一套通用型变速器数据采集系统。系统采用Mega128作为主控芯片,通过USB接口与PC进行通讯;PC端采集分析软件进行数据分析,设计了软件抗干扰模块,使用浮动加权算法进行滤波处理;最终将自动变速器换档工作时序图呈现给用户。介绍了系统硬件框架,给出了USB固件流程设计、主控单片机软件流程设计、信号识别算法、抗干扰算法和浮动加权滤波算法设计。     

智能卡微电流及逻辑特性测试系统研究

针对ISO7816智能卡电气特性和逻辑特性检测原理,介绍了一种新型智能卡微电流及逻辑特性测试系统的设计方法。该系统主要由主控模块、数据采集、传输与存储模块、逻辑测试模块组成。智能卡管脚输入或输出电流通过电流到电压的转换,经过调理芯片,确保每路模拟信号准确可靠;数据采集与传输模块采用高速单片机,用24位高精度A/D进行数据采集,将采集到的数据实时存储到FLASH存储模块中,并通过串口将数据发送给上位机。测试结果表明,系统工作良好。     

电动拖拉机驱动系统的整体设计

电动农机的电驱动系统主要包括电驱动系统试验台的硬件设计、电驱动测试系统的二次开发。在电驱动系统试验台应具有通用性和可扩展性的功能基础上,对试验台进行模块化划分,主要工作模块包括电源检测模块、动力输出模块、负载模拟模块和数据采集模。根据试验台各个模块的功能分析及传感器等设备的选型,自行设计了电驱动系统试验台;运用LabVIEW图形化可编程软件,进行电驱动系统试验台测试系统主界面的开发,并在LabVIEW中实现试验数据的采集、存储、显示等功能。     

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...     

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.     

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。     

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...     

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。     

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。     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

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.     

RLS and LMS blind adaptive multi-user detection method and comparison in acoustic communication

RLS and LMS blind adaptive multi-user detection algorithm and multi-user detector was proposed to solve the problem of multi-user signal detection problem encountered in underwater acoustic communication networks.In simulation analysis,RLS and the LMS blind adaptive multi-user detector were designed and tested for synchronous and asynchronous multi-user communication process.The results of SIR comparison and MMSE comparison show that,both of the two methods can realize blind adaptive detection when any user change in multi-user communication,during this process,the training communication sequences are not needed.The RLS algorithm has about 5 dB higher in SIR compared with LMS algorithm,and the convergence velocity of RLS algorithm is also higher than LMS algorithm when the communication users change.RLS algorithm has better ability in multi-user detection than that of LMS algorithm,and it has great attraction and guiding significance for solving the problem of multiple access interference(MAI) in multi-user communication.     

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...