Fabrication and thermal performance of grooved-sintered wick heat pipe简

Some novel grooved-sintered composite wick heat pipes（GSHP） were developed for the electronic device cooling.The grooved-sintered wicks of GSHP were fabricated by the processes of oil-filled high-speed spin forming and solid state sintering.The wick could be divided into two parts for liquid capillary pumping flow：groove sintered zone and uniform sintered zone.Both of the thermal resistance network model and the maximum heat transfer capability model of GSHP were built.Compared with the theoretical values,the heat transfer limit and thermal resistance of GSHP were measured from three aspects：copper powder size,wick thickness and number of micro grooves.The results show that the wick thickness has the greatest effect on the thermal resistance of GSHP while the copper powder size has the most important influence on the heat transfer limit.Given certain copper powder size and wick thickness,the thermal resistance of GSHP can be the lowest when micro-groove number is about 55.     

Modelling and simulation of contact force in cold rotary forgin简

Cold rotary forging is an advanced and complex metal forming technology with continuous local plastic deformation. Investigating the contact force between the dies and the workpiece has a great significance to improve the life of the dies in cold rotary forging. The purpose of this work is to reveal the contact force responses in cold rotary forging through the modelling and simulation. For this purpose, a 3D elastic-plastic dynamic explicit FE model of cold rotary forging is developed using the FE code ABAQUS/Explicit. Through the modelling and simulation, the distribution and evolution of the contact force in cold rotary forging is investigated in detail. The experiment has been conducted and the validity of the 3D FE model of cold rotary forging has been verified. The results show that： 1） The contact force distribution is complex and exhibits an obvious non-uniform characteristic in the radial and circumferential directions; 2） The maximum contact force between the upper die and the workpiece is much larger than that between the lower die and the workpiece; 3） The contact force evolution history is periodic and every period experiences three different stages; 4） The total normal contact force is much larger than the total shear contact force at any given time.     

Two-stage stochastic approach for spinning reserve allocation in dynamic economic dispatch简

A novel approach was proposed to allocate spinning reserve for dynamic economic dispatch.The proposed approach set up a two-stage stochastic programming model to allocate reserve.The model was solved using a decomposed algorithm based on Benders＇ decomposition.The model and the algorithm were applied to a simple 3-node system and an actual 445-node system for verification,respectively.Test results show that the model can save 84.5 US $ cost for the testing three-node system,and the algorithm can solve the model for 445-node system within 5 min.The test results also illustrate that the proposed approach is efficient and suitable for large system calculation.     

Mechanical,piezoelectric and some thermal properties of (B3) BP under pressure简

Some compounds of group III-V semiconductor materials exhibit very good piezoelectric, mechanical, and thermal properties and their use in surface acoustic wave （SAW） devices operating specially at GHz frequencies. These materials have been appreciated for a long time due to their high acoustic velocities, which are important parameters for active microelectromechanical systems （MEMS） devices. For this object, first-principles calculations of the anisotropy and the hydrostatic pressure effect on the mechanical, piezoelectric and some thermal properties of the （B3） boron phosphide are presented, using the density functional perturbation theory （DFPT）. The independent elastic and compliance constants, the Reuss modulus, Voigt modulus, and the shear modulus, the Kleinman parameter, the Cauchy and Born coefficients, the elastic modulus, and the Poisson ratio for directions within the important crystallographic planes of this compound under pressure are obtained. The direct and converse piezoelectric coefficients, the longitudinal, transverse, and average sound velocity, the Debye temperature, and the Debye frequency of （B3） boron phosphide under pressure are also presented and compared with available experimental and theoretical data of the literature.     

Mathematical model of slotting manufacture and simulation for cosine gears简

A slotting method for cosine gears was proposed by using the involute cutter based on the conjugate theories of digital surface and gear meshing. The slotting model between the cosine tooth surface represented by discrete points and the cutter figuration determined by analytic function was built for their geometrical relationship and conjugate motion during the machining process. Conjugate points in the cutter section corresponding to the discrete points on the cosine gear tooth surface and the conjugate movements were solved. By using the flexible control of the CNC procedure, the active control of the cutting trace of the slotting cutter was accomplished and the envelop forming of the cosine gear was obtained. Based on the software C＋＋ and Matlab, the computer aided manufacturing （C;AM） system of the cosine gear was developed, and the simulation of the slotting process was accomplished. Several examples were provided to illustrate the approach. The result of the simulation demonstrates that the proposed slotting method is feasible.     

Finite difference method for dynamic response analysis of anchorage system简

Based on some assumptions, the dynamic analysis model of anchorage system is established. The dynamic governing equation is expressed as finite difference format and programmed by using MATLAB language. Compared with theoretical method, the finite difference method has been verified to be feasible by a case study. It is found that under seismic loading, the dynamic response of anchorage system is synchronously fluctuated with the seismic vibration. The change of displacement amplitude of material points is slight, and comparatively speaking, the displacement amplitude of the outside point is a little larger than that of the inside point, which shows amplification effect of surface. While the axial force amplitude transforms considerably from the inside to the outside. It increases first and reaches the peak value in the intersection between the anchoring section and free section, then decreases slowly in the free section. When considering damping effect of anchorage system, the finite difference method can reflect the time attenuation characteristic better, and the calculating result would be safer and more reasonable than the dynamic steady-state theoretical method. What is more, the finite difference method can be applied to the dynamic response analysis of harmonic and seismic random vibration for all kinds of anchor, and hence has a broad application prospect.     

机器人避障模型简

研究了机器人在存在12个不同形状、不同大小障碍物的平面区域内避障的最短路径及最短时间路径问题.结合图论中的Dijsktra算法,获得了机器人避障的最佳路线;并对最佳路线进行了平滑处理,分别建立了问题一、二的非线性规划优化模型;利用Maple软件和Lingo软件编程,求出了最短路径、最短时间路径及切点的坐标.     

Numerical simulation of tire/soil interaction using a verified 3D finite element model简

The compaction and stress generation on terrain were always investigated based on empirical approaches or testing methods for tire/soil interaction.However,the analysis should be performed for various tires and at different soil strengths.With the increasing capacity of numerical computers and simulation software,finite element modeling of tire/terrain interaction seems a good approach for predicting the effect of change on the parameters.In this work,an elaborated 3D model fully complianning with the geometry of radial tire 115/60R13 was established,using commercial code Solidwork Simulation.The hyper-elastic and incompressible rubber as tire main material was analyzed by Moony-Rivlin model.The Drucker-Prager yield criterion was used to model the soil compaction.Results show that the model realistically predicts the laboratory tests outputs of the modeled tire on the soft soil.     

Effects of parameters on rotational fine blanking of helical gear简

The application of fine blanking to the manufacturing of helical gears directly from a strip has been restricted due to the traditional linear cutting stroke of the punch and die. In this work, rotational fine blanking which combined the linear and rotational motion of punch and counterpunch was applied for the forming of helical gears. A three-dimensional （3D） rigid-plastic finite element model was developed on the DEFORM-3D platform. By finite element simulation and analysis, the influences of key parameters on the punch load and cut surface were investigated. It is shown that： 1） with increasing the counterforce or helical angle, the punch load and the depth of die roll increase; 2） with increasing blank holder force, the punch load increases while the depth of die roll decreases; 3） V-ring indenter facilitates an improvement in the quality. The results of this research reveal the deformation mechanism of rotational fine blanking of helical gears, and provide valuable guidelines for further experimental studies.     

Synthesis and ceramization of polycarbosilane containing beryllium简

Polycarbosilane containing beryllium （BPCS） precursors was prepared by the reaction of polycarbosilane （PCS） with beryllium acetylacetone （Be （acac）2）. The analysis of structures and components of BPCS demonstrates that their main structures are basically the same as PCS. Ceramization of BPCS precursors shows that BPCS precursors are organic below 600 °C and inorganic at 800 °C. At 1400 °C, BPCS precursors convert into silicon carbide ceramics. The ceramization of different beryllium content precursors were studied, which show that beryllium plays an important role in the inhibition of crystalline grain growth of β-SiC at high temperature and it can adjust the dielectric constant of silicon carbide ceramics.     

太阳能土壤源热泵蓄热过程中的数值模拟

建立了太阳能土壤源热泵系统蓄热过程的数学模型,在求解模型时考虑了换热器管壁和土壤的接触热阻,定义了一个综合换热系数;在蓄热量的计算上,把换热器沿深度方向上离散成M份,算出每段的蓄热量相价后得出总换热量。文中采用了有限单元法对地下垂直埋管周围土壤的非稳态温度场进行了数值模拟,分析了换热器周围土壤温度变化的规律。     

轧板热轧过程传热性能的数值模拟

通过建立数学模型，研究了轧板在粗轧、精轧过程中的温度变化．为了正确估计轧板的温度，应考虑轧板-轧辊接触面以及轧辊同的热传递．数值结果表明，轧辊的冷却作用对轧板温度分布有显著影响．此外，对轧板温度进行数值分析时须考虑氧化皮和轧板-轧辊接触面处润滑膜的影响．     

北方地区供暖情况下室内热环境数值分析

为研究建筑围护结构热工性能与供暖季室内散热器传热特性的关联性,采用一种修正的湍流k-ε模型对兰州地区某民用住宅室内热环境进行了数值分析,获得了该住宅在4种外墙类型情况下的散热器传热特性和室内流场、温度场分布。结果表明：在满足室内供暖温度要求条件下（室内平均温度达到18°C）,散热器表面对流换热能力随外墙导热系数的增大而增大;室内形成了明显的温度分层现象,外墙导热系数越大,接近地板的温度越低,形成的＂冷气湖＂厚度自东墙朝西墙方向逐渐变薄;选择不同的外墙类型,室内速度场的变化很微弱。     

智能模拟热电偶给定仪的研制

研制了一种智能模拟热电偶给定仪．该仪器具有便携式、智能化、键盘操作、低功耗、高精度及高稳定性等特点，可在工业过程控制工程中，用于校验各种系列的热电偶温度变送器、各类模拟的数字温度显示器和记录仪，是工作现场较实用的一种校验仪．     

低层双坡屋面房屋表面风压的数值模拟

结合低层民房风荷载及抗风性能的研究，采用基于Reynolds时均方程和标准κ-ε湍流模型的数值模拟方法，对一低层双坡屋面房屋的周围风场和表面风压进行了数值模拟．数值模拟采用具有良好拓扑性的四面体单元对计算区域进行网格划分，用顶点中心格式的有限容积法对控制微分方程进行离散，以解压力耦合方程的半隐式法(SIMPLE算法)实现对非线性离散化方程的求解．通过与风洞试验值的比较，表明了数值模拟能较好地反映低层房屋表面风压的分布，所得到的风压系数与风洞试验数据能很好地吻合．     

Development of experimental study on coupled heat and moisture transfer in porous building envelope

A new facility was presented which can expediently and cheaply measure the transient moisture content profile in multi-layer porous building envelope. Then, a common multi-layer porous building envelope was provided, which was constructed by cement mortar-red brick-cement plaster. With this kind of building envelope installed in the south wall, a well-controlled air-conditioning room was set up in Changsha, which is one of typical zones of hot and humid climate in China. And experiments were carried out to investigate the temperature and moisture distribution in multi-layer building envelope in summer, both in sunny day and rainy day. The results show that, the temperature and humidity at the interface between the brick and cement mortar are seriously affected by the changes of outdoor temperature and humidity, and the relative humidity at this interface keeps more than 80% for a long-term, which can easily trigger the growth of mould. The temperature and humidity at the interface between the brick and cement plaster change a little, and they are affected by the changes of indoor temperature and humidity. The temperature and humidity at the interface of the wall whose interior surface is affixed with a foam plastic wallpaper are generally higher than those of the wall without wallpaper. The heat transfer and moisture transfer in the envelope are coupled strongly.     

Numerical simulation of heat transfer of latent functionally thermal fluid in tubes with coaxially inserted cylindrical bars in laminar

The heat transfer of latent functionally thermal fluid in three kinds of tubes with coaxially inserted cylindrical bars is numerically researched using equivalent specific heat model, and the flow fields are analyzed with field synergy field. It is found that in the tubes with coaxially inserted cylindrical bars, the heat transfer effects of functionally thermal fluid become more and more pronounced with the Ste decreasing. This is similar to be case of functionally thermal fluid flowing in smooth straight tubes. Compared with the results receiving from smooth straight tubes, the heat transfer of functional thermal fluid in tubes with coaxially inserted cylindrical bars has been significantly enhanced. And this effect becomes more apparent as the diameter of coaxially inserted cylindrical bars increases meanwhile, however, energy consuming of the tubes shows the same trend. Supported by the Key Project of National Natural Science Foundation of China (Grant No. 50436020)     

三种围护结构现场能耗检测方法的分析

现阶段,热流法、热箱法,热红外摄像仪法是我国测量外墙传热系数的主要方法。根据其自身的特点可用于不同季节与不同场所,但每种方法都不尽完善。对现有围护结构传热系数测定的主要方法进行了分析,并得出三种方法的优劣。     

机械工作过程的热信号模拟及失真研究

研究了机械工作过程的热信号模拟技术 .利用热信号模拟机械热态过程时 ,热信号模拟存在着一定程度的失真 .分析了导致热信号失真的原因 ,提出了减少热信号失真的方法 ,并通过仿真和实验验证了该方法的有效性     

Molecular dynamics simulation of thermal conductivities of superlattice nanowires

Materials with low thermal conductivity, high electric conductivity and high Seebeck coeffi-cient are desirable for high performance solid-state thermoelectric devices. The performance of thermoelectric devices depends on the figure of merit ZT, given by 2(/),ZTSTsl= where , , , STsl are the Seebeck coefficient, absolute temperature, electrical conductivity and thermal conductivity, respectively. To compete with the phase change based energy conversion devices economically, materials with …