欧姆接触中接触电阻率的计算

从欧姆接触电阻率的定义出发,先从理论上介绍了热离子发射、热离子场发射和场发射三种不同情况下欧姆接触电阻率的计算公式,然后详细地从实验上综合各种测试方法,并讨论了其利弊．     

振动结构耦合动刚度的间接逆子结构辨识方法

耦合动刚度是复杂耦合结构振动分析中的一个非常关键的参数,其精确辨识对于结构振动特性评估与控制设计非常重要。为将逆子结构动态分析方法推广应用于振动结构耦合动刚度辨识,在建立了耦合动刚度逆子结构分析模型后,提供一种通过频率响应函数反演耦合结构动刚度的方法——间接逆子结构辨识法。最后采用单点和三点耦合二级子结构“质量-胶垫”实验模型,验证了逆子结构辨识方法的理论有效性,包括辨识精度的误差分析.实验与理论分析结果的一致性表明,与现有的直接逆子结构动态分析方法相比,该方法较常规辨识方法具有适用条件范围更宽、辨识精度更高的优点,可以提高工程结构参数的辨识精度,具有更好的工程应用可行性与有效性,为逆子结构动态分析方法辨识振动结构耦合动刚度进一步提供理论依据。     

Laser cladding of copper with molybdenum for wear resistance enhancement in electrical contacts

Laser cladding of Mo on Cu has been attempted with the aim of enhancing the wear resistance and hence increasing the service life of electrical contacts made of Cu. In order to overcome the difficulties arising from the large difference in thermal properties and the low mutual solubility between Cu and Mo, Ni was introduced as an intermediate layer between Mo and Cu. The Ni and Mo layers were laser clad one after the other to form a sandwich layer of Mo/Ni/Cu. Excellent bonding between the clad layer and the Cu substrate was ensured by strong metallurgical bonding. The hardness of the surface of the clad layer is seven times higher than that of the Cu substrate. Pin-on-disc wear tests consistently showed that the abrasive wear resistance of the clad layer was also improved by a factor of seven as compared with untreated Cu substrate. The specific electrical contact resistance of the clad surface was about 5.6 × 10⁻⁷ Ω cm².     

电磁轨道炮高速滑动接触电阻的定量表征

从描述电磁轨道炮炮口电压波形的场路模型出发,构建了电枢/轨道高速滑动接触电阻与轨道电流波形、炮口电压波形、电枢膛内速度曲线和轨道结构参数之间的关系,依据此关系可定量表征电磁轨道炮高速滑动接触电阻。实例计算表明,电枢/轨道高速滑动接触电阻的变化依赖于轨道电流变化,对应电流上升段、平顶段和电流下降段。在平顶段接触电阻最小约0.2mΩ,在电流上升段和电流下降段,接触电阻达3mΩ。     

电磁轨道炮高速滑动接触电阻的定量表征

从描述电磁轨道炮炮口电压波形的场路模型出发,构建了电枢/轨道高速滑动接触电阻与轨道电流波形、炮口电压波形、电枢膛内速度曲线和轨道结构参数之间的关系,依据此关系可定量表征电磁轨道炮高速滑动接触电阻。实例计算表明,电枢/轨道高速滑动接触电阻的变化依赖于轨道电流变化,对应电流上升段、平顶段和电流下降段。在平顶段接触电阻最小约0.2 m,在电流上升段和电流下降段,接触电阻达3 m。     

具时变刚度的相对转动非线性动力系统的周期解问题

建立了一类具有时变刚度,非线性阻尼力和强迫周期力项的相对转动非线性动力系统. 运用Mawhin重合度理论,得到了该模型的周期解存在唯一性结果,推广了已有的结果, 并且列举了具体的例子来说明本文的结果是新的. 关键词： 相对转动非线性动力系统 时变刚度 周期解 存在唯一性     

电磁轨道发射器连续发射的滑动电接触

从滑动电接触电阻大小的角度,详细分析了在时序放电条件下,两颗重约为5 g的电枢,以速度为1 000 m/s,166 Hz连续发射试验。通过近似计算电流所流经轨道电阻及电枢体电阻所产生的温升,对滑动电接触电阻的影响。结果表明:连续发射运行模式下,受轨道表面温度上升的影响,第二发电枢的滑动接触电阻略高于第一发电枢的滑动接触电阻,表面滑动电接触性能受到温升的影响,在两连发的发射情况下,其影响虽不是很大,但多发高频连续发射就必须考虑热管理问题。      

Study of linearity for a high dynamic range calorimeter

A high dynamic range calorimeter has been designed for the DArk Matter Particles Explore(DAMPE) satellite. It consists of 308 BGO crystals, multi-dynode readout PMTs and front end electronics system. We have built on previous research to show that BGO fluorescence should not be saturated by high electron energy density under DAMPE's energy range. A BGO fluorescence simulator is set up to calibrate the energy range of the dynodes, while a cosmic-ray unit is used to calibrate 1 MIP with the ADC count in dynode 8. Linearity is achieved for the dynamic range from 0.5 MIPs to 1.26×105MIPs. The requirements of DAMPE can thus be satisfied.     

玻璃钢低温下导热及接触热阻的实验研究

利用稳态法测试了固体复合材料在不同温度下的导热系数及复合材料与铜之间的接触热租。在90K~300K的温度范围内,固体复合材料导热系数随温度的提高而增大,而当温度上升时,接触热阻降低,温度大于100K时,热阻变化较小。     

Compressibility determination by electrical resistance measurement: a universal method for both crystalline and amorphous solids

A new method is introduced for investigating the compressibility of solids under high pressure by in situ electrical resistance measurement of a manganin wire, which is wrapped around the sample. This method does not rely on the lattice parameters measurement, and the continuous volume change of the sample versus pressure can be obtained. Therefore, it is convenient to look at the compressibility of solids, especially for the X-ray diffraction amorphous materials. The I–II and II–III phase transition of Bi accompanying with volume change of 4.5% and 3.5% has been detected using the method, respectively, while the volume change for the phase transition of Tl occurring at 3.67 GPa is determined as 0.5%. The fit of the third-order Birch–Murnaghan equation of state to our data yields a zero-pressure bulk modulus K ₀=28.98±0.03 GPa for NaCl and 6.97±0.02 GPa for amorphous red phosphorus.     

接触角与液固界面热阻关系的分子动力学模拟

本文利用分子动力学方法模拟了液体在固体表面的 接触角及液固界面热阻, 并探讨了二者之间的关系. 通过分别改变液固结合强度和固体的原子性质来分析接触角和界面热阻的关系及变化趋势. 模拟结果显示增强液固间相互作用时, 接触角减小的同时界面热阻也随之单调减小; 而改变固体原子间结合强度和原子质量时, 接触角几乎保持不变, 但界面热阻显著改变. 固体原子间结合强度和原子质量影响界面热阻的原因是其改变了固体的振动频率分布, 导致液固原子间的振动耦合程度发生变化. 本文的结果表明界面热阻不仅与由接触角所表征的液固结合强度有关, 还与液固原子间的振动耦合程度有关. 接触角与界面热阻间不存在单值的对应关系, 不能单一地将接触角作为液固界面热阻的评价标准. 关键词： 液固界面 接触角 界面热阻 分子动力学模拟     

Study of top and bottom contact resistance in one organic field-effect transistor

This paper reports that the organic field-effect transistors with hybrid contact geometry were fabricated, in which the top electrodes and the bottom electrodes were combined in parallel resistances within one transistor. With the facility of the novel structure, the difference of contact resistance between the top contact geometry and the bottom contact geometry was studied. The hybrid contact devices showed similar characteristics with the top contact configuration devices, which provide helpful evidence on the lower contact resistance of the top contact configuration device. The origin of the different contact resistance between the top contact device and the bottom contact device was discussed.     

Improvement of the light output and contact resistance of InGaN-based light-emitting diodes based on tantalum-doped indium tin oxide as p-type electrodes

This paper reports that highly transparent and low resistance tantalum-doped indium tin oxide (Ta-doped ITO) films contacted to p-type GaN have been prepared by the electron-beam evaporation technique. The Ta-doped ITO contacts become Ohmic with a specific contact resistance of $\sim 5.65\times 10^{ - 5}$~$\Omega \cdot$cm$^{2}$ and show the transmittance of $\sim $98% at a wavelength of 440~nm when annealed at 500~\du. Blue light emitting diodes (LEDs) fabricated with Ta-doped ITO p-type Ohmic contact layers give a forward-bias voltage of 3.21~V at an injection current of 20~mA. It further shows that the output power of LEDs with Ta-doped ITO contacts is enhanced 62% at 20~mA in comparison with that of LEDs with conventional Ni/Au contacts.     

Specific contact resistance of IGZO thin film transistors with metallic and transparent conductive oxides electrodes and XPS study of the contact/semiconductor interfaces

In this work, the specific contact resistance (ρ_c) between amorphous indium-gallium-zinc-oxide (IGZO) semiconductor and different contact electrodes was obtained from thin film transistors (TFTs). Ti/Au (10/100 nm), aluminum doped zinc oxide (AZO, 100 nm) and indium tin oxide (ITO, 100 nm) were used as source/drain electrodes to fabricate IGZO TFTs. Chemical states of the contacts/semiconductor interfaces were examined by depth profile X-ray photoelectron spectroscopy (XPS) analysis to explain the origin of the differences on specific contact resistance. The lowest ρ_c achieved using Ti/Au was related to the formation of a TiO_x interlayer due to oxygen atoms diffusing out from the semiconductor under layer, increasing the carrier concentration of IGZO at the interface and lowering the ρ_c. On the contrary, no interfacial reactions were observed between IGZO and AZO or ITO source/drain. However, IGZO resistivity increased with ITO contacts likely due to oxygen vacancies filling during ITO deposition. This fact seems to be the origin of the high contact resistance between IGZO and ITO, compared to IGZO-AZO and IGZO-Ti/Au interfaces.     

晶体硅太阳电池双层电极优化分析与实验研究

相对于单层电极结构,优化的前表面双层电极能够明显减小功率损失,改善晶体硅太阳电池的电学特性．本文对晶体硅太阳电池的双层电极进行了优化分析和实验研究.通过扫描电子显微镜观测将双层电极的截面抽象为更接近于实际的半椭圆型,建立了太阳电池前表面的双层电极模型,理论分析了双层电极的电学损失和光学损失.结合丝网印刷后光诱导电镀太阳电池的实验,得到了理论和实验上的最优化光诱导电镀增厚电极厚度与丝网印刷电极宽度的关系.所得到的理论和实验结果符合良好.由于并不涉及电极制备的具体技术,双层电极理论模型普遍适用于多种类型的双层电极结构.     

A Dynamic Model for a Single Helicopter in the Low Airspace with Telegraph Poles and Electrical Wire

In this paper, we propose a dynamic model for a single helicopter in the low airspace with telegraph poles and electrical wire. The numerical results show that the proposed model can qualitatively describe the helicopter's velocity, safe distances, and safe sphere when it runs across the obstacle consisting of telegraph poles and electrical wire.     

X-ray photoelectronic spectroscopy of the processes of interaction between elements in contact layers on InP

Using the method of x-ray photoelectronic spectroscopy, we investigated of the interaction of gold-containing contact layers and indium phosphide in the process of thermal burning-in. We determined the dependence of the depth of the InP layer that had entered into interaction with the metal of the contact on the type of alloying admixture and the gold layer thickness. Institute of Electronics, National Academy of Sciences of Belarus, 22, Logoiskii Trakt, Minsk, 220090, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 1, pp. 144–147, January–February, 1999.     

Estimation of thermal contact resistance and thermally induced optical effects in single-coated optical fibers

In this study, a conjugate gradient method based on an inverse algorithm is applied to estimate the unknown time-dependent thermal contact resistance in a single-coated optical fiber, which is subjected to transient thermal loading. While knowing the temperature history at the measuring position, no prior information is needed on the functional form of the unknown contact resistance. The temperature data obtained from the direct problem are used to simulate the temperature measurement. The influence of measurement errors, initial guess values, and measurement locations upon the precision of the estimated results is also investigated. Results show that an excellent estimation on the time-dependent thermal contact resistance, temperature distributions, thermally induced microbending loss, and refractive index changes can be obtained for the case considered in this study.     

量子霍尔电阻计量技术的应用与分析

目前国际公认精度最高的现代电阻计量技术是量子霍尔电阻计量技术,但是其量子化、非连续特性使它在实际计量应用中受到很多限制。本文围绕先进的电阻比较与计量技术进行分类对比与分析,同时为实现10E-8量级相对不确定度的电阻溯源给出可行的技术方案。最后,针对不同方案给出分析结论,为相关计量实验室根据自身条件建立高精度电阻计量标准提供重要参考。