并联平板重力热管传热性能实验研究

为了研究安装角度、工质及管径对并联平板重力热管传热性能和启动特性的影响,本文搭建了性能测试实验台并进行了对比实验研究.实验结果表明:在90°～60°倾角范围内,倾角对热管传热性能的影响不明显,随倾角的继续减小,热管运行热阻增大,传热极限减小;在低加热功率下充注丙酮的热管具有更好的传热性能,而在高加热功率时充注乙醇的热管...     

热源温度对导热系数测量的影响

基于稳态平板法研究了不同热源温度对橡胶样品的导热系数测量值的影响。利用多项式拟合法对实验数据进行处理和分析,并将实验值与公认值相对照。结果表明,热源温度为60℃是最合适的,在此温度下实验的实际总耗时相对较短,并且导热系数测量值最准确,其相对不确定度最小。     

Influence of Grain Boundaries on the Electrical Conductivity of Copper Alloys

Technical Physics - The experimentally found insensitivity of the resistivity of Cu–Cr and Cu–Cr–Zr alloys to structural modifications in alloy specimens subjected to severe...     

Influence of pH on Nanofluids' Viscosity and Thermal Conductivity

Aiming at the dispersion stability of nanopartieles regarded as the guide of heat transfer enhancement, we investigate the viscosity and the thermal conductivity of Cu and Al2O3 nanoparticles in water under different pH values. The results show that there exists an optimal pH value for the lowest viscosity and the highest thermal conductivity, and that at the optimal pH value the nanofluids containing a small amount of nanoparticles have noticeably higher thermal conductivity than that of the base fluid without nanoparticles. For the two nanofluids the enhancements of thermal conductivity are observed up to 13% （Al2O3-water） or 15% （Cu-water） at 0.4 wt%, respectively. Therefore, adjusting the pH values is suggested to improve the stability and the thermal conductivity for practical applications of nanofluid.     

Influence of Gravity and Taper on the Vibration of a Standing Column

The stability and natural vibration of a standing tapered vertical column under its own weight are studied. Exact stability criteria are found for the pointy column and numerical stability boundaries are determined for the blunt tipped column. For vibrations we use an accurate, efficient initial value numerical method for the first three frequencies. Four kinds of columns with linear taper are considered. Both the taper and the cross section shape of the column have large influences on the vibration frequencies. It is found that gravity decreases the frequency while the degree of taper may increase or decrease frequency. Vibrations may occur in two different planes.     

Process Physics: Inertia, Gravity and the Quantum

Process Physics models reality as self-organising relational or semantic information using a self-referentially limited neural network model. This generalises the traditional non-process syntactical modelling of reality by taking account of the limitations and characteristics of self-referential syntactical information systems, discovered by Gödel and Chaitin, and the analogies with the standard quantum formalism and its limitations. In process physics space and quantum physics are emergent and unified, and time is a distinct non-geometric process. Quantum phenomena are caused by fractal topologicaldefects embedded in and forming a growing three-dimensional fractal process-space. Various features of the emergent physics are briefly discussed including:quantum gravity, quantum field theory, limited causality and the Born quantum measurement metarule, inertia, time-dilation effects, gravity and the equivalence principle, a growing universe with a cosmological constant, black holes and event horizons, and the emergence of classicality.     

Effects of Localized Interface Phonons on Heat Conductivity in Ingredient Heterogeneous Solids

Phonons are the primary heat carriers in non-metallic solids. In compositionally heterogeneous materials, the thermal properties are believed to be mainly governed by the disrupted phonon transport due to mass disorder and strain fluctuations, while the effects of compositional fluctuation induced local phonon states are usually ignored.Here, by scanning transmission electron microscopy electron energy loss spectroscopy and sophisticated calculations, we identify the vibrational properties of in...     

The Influence of Nonconductive Disk-Shaped Inclusions on the DC Conductivity of Materials

Technical Physics - The influence of nonconductive disk-shaped inclusions (cracks) on the dc conductivity of a conducting medium has been considered. The functional dependences of an additional...     

Electronic Heat Conductivity of a Partially Ionized Hydrogen Plasma

The electronic contribution of the translational heat conductivity of a partially ionized hydrogen plasma is determined, starting from a quantum kinetic equation, which takes into account the two particle scattering between the free charge carriers as well as electron-atom collisions. Plasma effects are included by statically screened potentials. In connection with a mass action law, the influence of the different collision terms on the electron heat conductivity is shown. An estimation is given for the contribution of the atoms. The pressure ionization (Mott effect) is described by a minimum behaviour of the heat conductivity.     

On the Influence of External Elastic (Electromagnetic) Forces on the Gravity

Consequences of the possible effect of external elastic (electromagnetic) forces applied to a test body on the gravity are considered phenomenologically. The results of experimental estimates of the coefficients of interaction between elastic and gravitational forces are briefly described.     

低温预冷换热规律及表面改性影响研究

调研了低温管路预冷及两相换热的研究现状,阐述了低温预冷瞬态换热特性;介绍了金属表面改性对预冷规律的影响,仿真了低导热涂层管的预冷换热规律.研究发现:液氮预冷主要由膜态沸腾支配,且预冷耗时较长;液氢预冷未见膜态沸腾,预冷耗时更短.促进膜态沸腾向过渡沸腾的更早转化有利于预冷加速,且转化温度迁移可通过内壁表面结构改性实现,可...     

载波相位对超短脉冲时间重心的影响

以Gauss、Hyperbolic Secant、Lorentz三种脉冲为例,利用理论推导和数值模拟的方法研究了载波相位对超短脉冲时间重心的影响,并给出了三种脉冲的时间重心与载波相位的解析表达式和数值模拟的图形.研究结果表明:当脉冲包络的宽度短于一个光学振荡周期时,载波相位对超短脉冲的时间重心开始有较显著的影响.     

晶体和非晶体导热性能实验探讨

在高中物理"固体和液体"一节中,需要做云母片和玻璃片的导热性能实验,主要用来说明两个问题,一是利用云母片上熔化的蜡斑呈椭圆形说明单晶体导热性能各向异性这一物理特性;二是利用玻璃片上熔化的蜡斑呈圆形说明非晶体导热性能各向同性,并与单晶体的导热性相互比较.这个传统的实验说来容易,但凡亲自做过这个实验的老师都知道要想使这个实验达到预想的效果并不容易.     

Heat Conductivity of One-Dimensional Carbon Chain in an External Potential

The heat transport m a one-dimensional （ID） carbon nanowire （CNW） lying in an external potential with different amplitudes and periods is studied by the non-equilibrium molecular dynamics method. It is found that the thermal conductivity of CNW is always anomalous, increasing with the CNW length and obeying the power law k- N, in which a decreases with the increasing external potential amplitude. The thermal conductivity could be enhanced by the external potential with rather larger amplitudes, which means that an applied external potential could be an efficient tool to improve the heat conductivity of a real 1D material In addition, the effect of different periods of the external potential is studied, finding the external potential with an incommensurate period leads to the smaller a value.     

Influence of Gravity on Structure of Colloidal Crystal Using Simulated Microgravity

将重水(D2O)和水(H2O)以一定比例混合来匹配直径为110 nm的聚苯乙烯带电小球的密度,并利用Kossel衍射方法测量了胶体晶体的结构和晶格常数等参数．通过将密度匹配(g=0)和没有进行密度匹配(g=1)的实验结果的对比,发现重力将会使样品池中胶体晶体的晶格常数随高度的变低而变小．这一结果表明,在带电粒子胶体晶体的研究中有必要考虑重力的影响     

用Origin处理导热系数测定实验的数据

基于用稳态法测量不良导体的导热系数实验,为了求得更为精确的导热系数,用origin软件处理实验数据,拟合出温度和时间的曲线,并求得冷却速率及导热系数.     

The First Principle Formula of the Relativistic Heat Conductivity of Coulomb Electronic Plasmas

Making use of the relativistic BBGKY technique,the relativistic generalization of Landau collision integral is botained.Furthermore,we calculate the relativistic hydrodynamic modes up to the second order in the hydrodynamic wave number.Combining Resibois‘ method,we present the first principle formula of the relativistic heat conductivity of Coulumb electronic plasmas for low-order corrections.     

水滴对汽化热实验的影响

分析水的汽化热实验中误差的产生原因,重点探讨蒸气导管的选择对汽化热测量的影响,为提高实验精度、减小误差提出了合理而简便的改进措施。     

零重力点热源马兰戈尼FTM数值模拟

采用界面跟踪法FTM(Front-Tracking Method), 研究点热源流场中由Marangoni效应引起的液滴运动。模拟不同的Marangoni(Ma)数下液滴的运动。研究发现液滴运动速度先迅速增大到稳定迁移速度, 而后下降, 在t=1.2时出现反转, 速度随Ma数的增加而增加。液滴内部存在与Hill球涡相同的回流。随着Ma数的增大, Hill球涡进行分裂, 且涡旋中心有轻微的移动。同时温度场末端拓扑结构出现两次分叉。第一次分叉出现在下临界Ma数, 最低温度点由滞止点跳进液滴内部; 第二次分叉出现在上临界Ma数, 内部的壳型冷却区从中心点破裂, 出现一个环面型冷却区。