Broad-Band Microwave Voltmeter Using Thermoelectric Effects of Hot Carriers

The performance, especially of the minimum detectable voltage, the dynamic range, and the frequency characteristics on the microwave voltmeter based on the thermoelectric effects of hot carriers in a semiconductor placed in the strip line are described. Parasitic reactance of whisker and mount may be neglected in comparison with spreading resistance of not less than 500 ?, so that broad-band microwave voltmeter can be obtained. The VSWR was less than 1.2 within the range of frequency from 1 to 12.4 GHz. Making use semiconductor of low resistivity and small diameter point contact diode, a highly sensitive voltmeter is obtained. It was found that the dynamic range depends on the resistivity and the diameter of the electrode.     

热电制冷强化风冷散热模块的工作特性分析

热电制冷器(TEC)可以强化散热器冷却性能,但受热端散热强度、工作电流、工作热负荷等参数影响较大。本文建立了TEC强化风冷散热模块的有限元分析模型,对其温度分布、工作特性进行了系统的理论和实验研究,并提出了确定TEC强化风冷散热模块有效工作电流、有效热负荷和有效制冷系数范围的方法。仿真和实验结果表明:特定的TEC强化风冷散热模块存在一个极限热负荷Q_c,max,仅在工作热负荷Q_cc,max,且TEC工作电流处在有效范围内时,才可获得比无TEC的风冷散热模块更低的芯片结温,即TEC表现出强化散热器冷却性能的特点;有效工作电流范围会随Qc的增大而减小;增大热端散热强度可以降低芯片结温,但对于提升Q_c,max效果较小;制冷系数(COP)在有效范围内存在一个极值点,小于此值时芯片结温会随COP的减小而迅速增大。     

A Mechanism for the Oxidation-Related Influence on the Thermoelectric Behavior of Palladium

Oxidation of thermocouple elements can degrade the accuracy of thermocouple-based temperature measurements. As a particular example of such effects, oxidation of the Pd element of a platinum/palladium thermocouple is known to increase the thermoelectric emf by an amount equivalent to a temperature change of the order of 100 mK to 200 mK at 420 °C (G. W. Burns, D. C. Ripple, Proceedings of TEMPMEKO ‘96, 6th International Symposium on Temperature and Thermal Measurements in Industry and Science. Levrotto and Bella, Torino, 1997, 171–176). A possible physical mechanism to explain how oxidation affects the thermoelectric output of a Pt/Pd thermocouple is proposed. The analysis hinges on the hypothesis that the oxide-induced strain within the Pd thermoelement leads to a change in the Seebeck coefficient, and therefore to the thermoelectric emf. A theoretical model relating deformation of the palladium lattice to the change in the Seebeck coefficient is presented. The level of agreement between the calculation and the experimental observations suggests that oxide-induced strain in the Pd thermoelement is a likely explanation for the change in thermoelectric output of a Pt/Pd thermocouple within the temperature range where oxidation is active.     

Ge1-xInxTe微观结构对热电性能的影响

在GeTe中掺杂In能够引入共振能级, 但其微观结构对热电性能的影响还不明确。本研究采用熔炼-淬火-退火并结合放电等离子体烧结(SPS)的方法制备了系列Ge_1-xIn_xTe样品, 采用XRD、SEM、激光导热仪和热电性能分析系统(ZEM-3)对其微观结构和热电性能进行了研究。结果表明, 随着In元素的掺入, Ge_1-xIn_xTe的晶胞体积减小、人字鱼骨结构变小、晶界增多, 导致晶格热导率降低, 获得的最低热导率为2.16 W·m ^-1·K ^-1。同时, 掺杂In引入了共振能级, 降低了载流子浓度, 使塞贝克系数以及功率因子增大。当In掺杂量x为0.03时, Ge_1-xIn_xTe在600 K时获得最大ZT值1.15, 比GeTe提升了26.4%, 表明调整Ge_1-xIn_xTe的微观结构可以有效提升热电性能。     

分布式操作系统MDS／DOS的设计与实现

介绍了ＭＤＳ／ＤＯＳ的设计思想和部分实现技术。ＭＤＳ／ＤＯＳ是在微机操作系统ＭＳＤＯＳ的基础上，通过增加分布式通信与资源管理模块（ＤＣＲＭ）、分布式命令解释器（ＤＣＩ），并建立相应的通信机制后修改扩充而成。它已实现了分布式操作系统的基本功能。     

Influence of Distributed Blowing-In on a Turbulent Boundary Layer on a Body of Revolution

Journal of Engineering Physics and Thermophysics - A computational-experimental analysis of the effectiveness of stationary distribution of air blowing-in through a perforated surface on the...     

一种分布式OS自动生成系统模型

现行分布式ＯＳ在理论和研制方法上仍存在一些问题，对此，我们提出了一种集智能型、集成化和可塑性于一体的分布式ＯＳ自动生成系统模型（ＤＯＳＡＧＳ）。用此模型生成分布式ＯＳ的过程几乎达到智能化、自动化和工程化的程度，所生成的分布式ＯＳ具有广泛的适应性和实用性。     

The Influence of Switching between Chaotic Regimes on the Correlation Characteristics of Nonlinear Systems

Technical Physics Letters - The problem of dynamic regime diagnostics in nonlinear systems using their experimental time series is studied in the presence of switching between various oscillatory...     

AgSn18SbTe20无铅中温热电材料的粉末冶金法制备工艺及其对性能的影响

研究了制备p型AgSn₁₈SbTe₂₀无铅热电材料的机械合金化(MA)结合放电等离子烧结(SPS)工艺, 调查了MA过程中球磨时间和SPS温度对材料电热传输性能和热电优值的影响, 分析了样品的物相和显微结构。研究表明, 适当延长球磨时间和降低烧结温度, 可以有效提高材料的热电性能。优化制备条件可以实现59%的性能提升, 最佳条件(球磨12 h、SPS温度743 K)下制备的样品ZT值在723 K达到0.62。     

电弧炉的运行工况对电能计量的影响

运行中的电弧炉因快速的、随机的功率波动,带来的电压闪变及波形畸变使得传统的计量方式不适用冲击性负荷下的计量.文章首先分析了电弧炉的运行特点,通过模拟实验,得出了这种现象形成的原因,并就如何消除冲击性负荷对计量的影响提出了自己的看法.     

制冷机工况变化对低温泵抽气特性的影响

低温泵的冷源是小型气体制冷机。制冷系统在长期运行中可能发生种种故障，使制冷工况发生变化。制冷机制冷工况的变化，对制冷机一，二级冷头的制冷量和制冷温度有明显影响，从而对低温泵抽气特性产生重大影响。     

Increasing the Efficiency of Laser Heat Treatment of a Lathe Tool with Allowance for the Influence of the Cutting Regimes

A complex approach to estimation of the process of cutting with a hardened tool is proposed. The choice of factors having the strongest influence on the durability value of cutting tools upon their laser treatment has been made and the significant influence of their interaction effects has been established. An adequate mathematical model of the cutting process has been constructed. It is shown that to achieve the greatest positive effect, irradiation of cutting tools should be carried out taking into account their particular operating conditions. It is recommended to use this model under working conditions to obtain the required durability of the tool under given operating conditions.     

太阳能半导体冰箱的性能分析

介绍了太阳能电池驱动的半导体制冷冰箱系统的基本结构,建立了太阳能电池驱动的半导体冰箱的理论模型,并对系统性能进行了数值模拟,分析了太阳辐射强度和环境风速的变化对太阳能半导体制冷系统性能的影响。研究表明针对设计的太阳能半导体制冷系统,在某一太阳辐射强度下,系统的制冷量输出最大,并且在辐射强度200～1000W/m^2时,制冷系数随着太阳辐射强度的减小而减小。在给定的工况下,环境风速增加使得系统工作电流朝靠近最佳工作电流数值方向增加。     

工艺条件对薄片陶瓷材料凝胶流延成型的影响

利用有机单体的聚合原理，成功进行了陶瓷薄片材料的凝胶流延成型。讨论了工艺条件对成型的影响。使用惰性气氛保护克服了单体聚合反应中的氧气阻聚问题，浆料在一定温度和气氛条件下能够顺利完成聚合反应。所成型的坯体具有良好的强度和柔韧性，在1550℃经2h烧结，烧结样品显微结构均匀，没有发现晶粒异常长大现象，烧结体致密度达到97．7％。     

Influence of Irradiation Sterilization on Polymers Used as Drug Carriers—A Review

Abstract

A survey was made of the influence of irradiation sterilization on relevant natural, semisynthetic, and synthetic polymers used for drug carrier system. The first part of the review deals with some general aspects of irradiation treatment and its use in the sterilization of pharmaceuticals. The second part reviews the information available in the literature on polymeric biomatenals used for carriers after irradiation sterilization. The influence of irradiation sterilization has been described for polyester, poly(ortho ester), different synthetic hydrogels, silicone derivatives, cellulose-derivatives, hyaluronic acid, different glucosides, collagen, and gelatine. Also, some limitations concerning the use of high-energy radiations for sterilization are given.     

溶液浓度对聚丙烯腈聚合动力学的影响

在试验的过程中,发现了动力学方程中转化率的理论值与实际值之间的差别,实际转化率的最大值为95%,而理论转化率的最大值为64%,经分析,认为体系浓度变化是造成这一差别的主要原因。为了进一步研究溶液浓度对聚合动力学的影响,将聚丙烯腈溶入二甲基亚砜,配制不同含固率的溶液,将溶液作为反应介质,以丙烯腈和丙烯酰胺为反应单体进行反应。结果发现,体系浓度与链终止速率常数的指前因子呈线性关系,即链终止速率常数的指前因子随体系浓度的增大而减小,动力学方程经浓度修正以后,在转化率小于50%时,转化率的理论值与实际值吻合得很好。