热管车刀的研制

本文根据实际车刀的要求,设计了一种新型热管车刀,并对热管车刀和普通车刀进行了比较详细的传热计算。最后,作了切削温度和刀具磨损对比实验,实验结果表明：（1）由于热管车刀有效地降低了切削区的温度,从而提高了切削效率2～3倍,刀具耐用度也有了明显的提高。（2）热管车刀的传热计算与实验结果基本相符,因此理论计算公式具有参考价值。（3）为热管新技术在车削加工中的应用提供了一个新的途径。（4）对高温耐热合金钢的加工具有重要意义。     

用于电子冷却的热管性能分析

进行了充水热管、铜棒及空热管的热性能对比实验,结果表明热管利用水的两相沸腾换热来对功率模块内的集中热源进行扩散,其热扩散能力大大高于以导热热扩散的金属基板,利于消除芯片中出现的热点,用于电子冷却比金属导热块有更大的优势,并且热源方向和重力对金属烧结粉末热管几乎没有影响.当蒸发端在冷凝端顶部时,槽道和丝网芯热管不理想,均温效果差.提出采用一种简化热管数学模型进行有限元模拟,大大缩短了计算时间和工作量.     

组合式热管蒸发器在污水源热泵中的应用

介绍了组合式热管蒸发器结构和工作原理.分析了组合式热管蒸发器传热过程.进行了实验研究.对污水人口温度一定的情况下,不同的污水流量对组合式热管蒸发器冷侧传热系数、热侧传热系数和总传热系数的影响,热管冷侧传热系数和热管热侧换热系数对热管总传热系数的影响以及冷热侧换热面积对热管总传热系数的影响进行了研究.     

某机载雷达的隔振系统性能研究

机载雷达振动环境恶劣,往往需要对其进行隔振系统设计.文中以机载雷达的隔振系统为研究对象,基于隔振的基本理论,构建隔振系统的力学模型,获得了系统功率谱密度的理论值.利用有限元法对隔振系统进行随机振动分析,获得了系统功率谱密度的仿真计算值.在不同刚度k和阻尼比ξ的条件下,对比分析理论计算值和仿真计算值,结果表明,仿真分析方...     

热管技术在余热回收方面的应用分析

介绍热管技术原理,阐明热管在传热方面的优势,对某卷烟厂气流式烘丝机进行热管式换热器余热回收计算分析。结果表明,热管换热器以热管的优良导热性为优势,在余热回收方面应用较为广泛。     

燃气与空气换热过程中热管的性能分析

以高温高压燃气加热高压空气为研究背景,针对3种典型的热管结构,建立了物理模型,并进行了传热计算,比较分析了3种热管在不同内径、速度场、温度场和压力场条件下的工作性能,可为高温高压热管换热设备的进一步开发研究和工程化应用提供理论支持。     

某无人机载雷达挂架结构设计

针对某无人机载雷达挂架结构的技术特点,开展了结构技术研究和实践工作,包括该挂架的结构形式、材料选择、工艺设计、表面处理和仿真分析等。为验证挂架的承载能力是否满足机载雷达的技术指标要求,基于有限元软件对其结构进行了有限元分析,计算了系统平飞状态和降落状态时挂架的刚强度以及机载雷达的倾斜角度。计算结果显示刚度和强度均满足使用要求。此外,实际应用显示,该挂架的使用稳定可靠,安装工艺简单、运输方便,达到了设计目标。     

基于ANSYS Icepak的热管模块设计与仿真分析

NVIDIA JETSON TX2高功率系统芯片的散热功率一般在25 W左右,一般的风扇与肋片式散热器组合的散热方式存在体积大、高度高、不方便整合在小型系统中等问题,而热管、风扇、铜鳍片散热器组合的散热方式具有高度低、体积小、传热效率高等优点。文中首先对热管模块进行结构设计;然后对热管模块设计的合理性进行计算验证,并利用ANSYS Icepak对热管模块进行热稳态仿真,发现主要芯片的温度都在要求范围内,表明设计合理;最后将热管模块装入系统进行温度测试。结果表明,主要芯片的计算、仿真与实验的温度基本一致。     

异型管在热管换热器中传热数值模拟研究

针对热管换热器中热管具有高效传热特性,在诸多领域有着极其重要的应用。应用fluent计算软件对三种不同形状的热管的传热性能进行研究,并研究三角形热管与四边形热管混排的传热性,并比较它们之间的传热效果。分析得出:圆形热管的传热系数从前排到后排近似符合抛物线分布;三角形热管的热管系数从前排到后排维持高的传热系数不变,在此热管换热器中三角形热管的综合传热性能最好,能起到强化传热的效果;正方形热管和正方形与三角形热管从前排到后排传热系数近似符合指数分布。     

微沟槽热管传热性能实验研究

为研究充液率、真空度和长度对热管传热性能的影响作用,利用基于虚拟仪器技术的热管传热性能测试平台对直径6mm的微梯形沟槽热管在不同充液率、不同真空度以及不同长度等条件下进行实验测试.实验表明:微沟槽热管的最佳充液率在(75～100)%之间.热管内必须具备足够低的真空度,且充液率需根据真空度的不同适当调整.热管长度缩短可以提高其传热性能,但长度较短时,需适当提高充液率.     

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.     

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....     

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.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.