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.     

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.     

风力发电机的建模及动态仿真

风力发电机的数学模型及动态仿真曲线,对风电场电力系统稳定性的研究及风水互补电力系统的研究提供了理论依据,有重要的现实意义。     

能耗模拟在建筑围护结构节能改造中的应用

以上海地区某宾馆建筑为研究对象,为降低能耗拟对建筑围护结构进行改造,有外墙加保温层、屋顶加保温层和外窗贴隔热膜3种改造方案.利用建筑能耗模拟软件对原有建筑及3种改造方案实施后的建筑进行了全年空调能耗模拟,并给出了经济性分析,由分析结果可以看出,采用外窗节能改造方案的经济性最好.     

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．     

热惰性指标对围护结构热稳定性量化作用机制

热惰性指标D是基于谐波分析法的建筑热稳定模型中的关键参数,为揭示热惰性指标对围护结构内热流波动的作用机制,首先基于对周期性非稳态热作用下围护结构传热过程的理论分析和求解,给出了热惰性指标与围护结构内温度波衰减及温度波数量的关系式,然后利用数值模拟方法分析了热惰性指标对围护结构内温度波衰减和延迟的影响,最后分析了热惰性指标对剧烈波动层厚度、内表面蓄热系数、多层围护结构的衰减倍数及延迟时间等热稳定性能参数计算的关键影响.研究表明:热惰性指标与围护结构内温度波衰减以及温度波数量存在定量关系式;对于相同形式的围护结构,D越大,衰减倍数及延迟时间越大,围护结构内温度波数量越多,热稳定性能越好;对于不同形式的多层围护结构,D越大,表明延迟时间越长,而衰减倍数的大小还与材料层的排顺有关,外保温比内保温围护结构能获得更大的衰减倍数;利用D=1确定温度剧烈波动层厚度为围护结构蓄热设计提供了新思路;内表面蓄热系数的计算主要与剧烈波动层内的热工参数有关.     

甘南农区藏式传统民居热环境

对甘肃省甘南藏族自治州迭部县哇曲村典型藏式民居冬、夏季室内外温湿度的测量,分析得出了藏族传统民居建筑热环境状况。结果表明：结合当地的历史、地理、气候等因素,哇曲村形成了独特的村落构成和单体民居建筑构造。藏族传统民居外围护结构具有较好的热工性能,建筑热环境的被动式调节使室内热舒适状况需要通过综合的、节能的手段来进一步改善。     

南方建筑非透明围护结构热工与节能设计

如何兼顾冬夏两季建筑供暖空调负荷和能耗,保证室内热环境质量,确定最适宜的热工特性,是长期困扰中国南方建筑围护结构热工与节能设计的难点。通过对夏热冬冷和夏热冬暖地区建筑在采暖、空调与自然通风条件下动态热过程的分析,研究了这一地区围护结构热特性与能耗的制约关系,以及对室内热环境与建筑热稳定性的作用机理。在兼顾冬季保温与夏季隔热的情况下,将建筑全年能耗作为控制目标,从室内热环境质量、节能效果、围护结构的安全性、可靠性、经济性和实用性等角度评价目前所采用的围护结构节能技术存在的问题,提出一种适宜南方气候的建筑围护结构热特性指标及构造形式。     

冷热循环作用下砂土地基能量桩热传递特性测试系统

能量桩是一种兼具换热和承担建筑荷载功能的新型建筑节能技术,为研究冷热循环温度影响下能量传递特性,设计了一套新型的能量桩模型实验及测试系统,较为系统地研究了砂土地基中预制单U型混凝土能量桩的传热特性。试验结果表明:在能量桩换热过程中,热量更易从桩体传递到土体;冷热循环中,桩身温度差异较小,温度沿桩身分布均匀;制热工况下能量桩在土体中的温度影响范围大于制冷工况,能量桩换热效率随着桩身与土体温度差异的减小而减小。     

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．