COMPARISON AND EVALUATION OF CURRENT REFERENCE GENERATION STRATEGIES FOR ACTIVE POWER FILTERS IN THREE-PHASE FOUR-WIRE SYSTEMS

For three phase four-wire active power filters （APFs）, several typical power theories and corresponding current reference generation strategies are induced, p-q, d-q, unify power factor （UPF） and instantaneous active current （IAC） methods are analyzed and compared with each other. The interpretation of active and reactive currents in non-sinusoidal and unbalanced three-phase four-wire systems is given based on the generalized instantaneous reactive power theory. The performance and the characteristic are evaluated, and the application conditions of current reference generation strategies are concluded. Simulation results under different source voltages and loads verify the evaluation result.

Current-voltage characteristics of individual conducting polymer nanotubes and nanowires

We report the current-voltage （I-V） characteristics of individual polypyrrole nanotubes and poly（3,4- ethylenedioxythiophene） （PEDOT） nanowires in a temperature range from 300 K to 2 K. Considering the complex structures of such quasi-one-dimensional systems with an array of ordered conductive regions separated by disordered barriers, we use the extended fluctuation-induced tunneling （FIT） and thermal excitation model （Kaiser expression） to fit the temperature and electric-field dependent I-V curves. It is found that the I-V data measured at higher temperatures or higher voltages can be well fitted by the Kaiser expression. However, the low-temperature data around the zero bias clearly deviate from those obtained from this model. The deviation （or zero-bias conductance suppression） could be possibly ascribed to the occurrence of the Coulomb-gap in the density of states near the Femi level and/or the enhancement of electron-electron interaction resulting from nanosize effects, which have been revealed in the previous studies on low-temperature electronic transport in conducting polymer films, pellets and nanostructures. In addition, similar I--V characteristics and deviation are also observed in an isolated K0.27MnO2 nanowire.

Effect of Zr and Sc on mechanical properties and electrical conductivities of Al wires

In order to obtain the Al wires with good mechanical properties and high electrical conductivities, conductive wires of Al-0.16 Zr, Al-0.16 Sc, Al-0.12Sc-0.04Zr（mass fraction, %） and pure Al（99.996%） were produced with the diameter of 9.5 mm by continuous rheo-extrusion technology, and the extruded materials were heat treated and analyzed. The results show that the separate additions of 0.16% Sc and 0.16% Zr to pure Al improve the ultimate tensile strength but reduce the electrical conductivity, and the similar trend is found in the Al-0.12Sc-0.04 Zr alloy. After the subsequent heat treatment, the wire with the optimum comprehensive properties is Al-0.12Sc-0.04 Zr alloy, of which the ultimate tensile strength and electrical conductivity reach 160 MPa and 64.03%（IACS）, respectively.

EFFECT OF RARE EARTH ON CONDUCTANCE OF ALUMINUM WIRE

Effects of Rare Earth(Hereafter RE)on the conductance of high-purity and industrial-purity aluminum wires have been studied.RE increases the resistivity of the high-purity aluminum.No evidence has been found that RE will decrease the resistivity of industrial-pure aluminum under various RE content including 0.3%Ce.The individual role of RE and its combined effects with Fe and Si have been discussed too.

Measurement of electrical conductivity of micron-scale metallic wires

Electrical conductivities of micron-scale aluminum wires were quantitatively measured by a four-point atomic force microscope (AFM) probe. This technique is a combination of the principles of the four-point probe method and standard AFM. This technique was applied to the 99.999% aluminum wires with 350 nm thickness and different widths of 5.0, 25.0 and 50.0μm. Since the small dimensions of the wires, the geometrical effects were discussed in details. Experiment results show that the four-point AFM probe is mechanically flexible and robust. The four-point AFM probe technique is capable of measuring surface topography together with local electrical conductivity simultaneously. The repeatable measurements indicate that this technique could be used for fast in-situ electrical properties characterization of sensors and microelectromechanical system devices.

Tunneling conductance in quantum wire/insulator/d_(x2-y2) + id_(xy) mixed wave superconductor junctions

Using the extended Blonder-Tinkham-Klapwijk （BTK） theory, this paper calculates the tunnelling conductance in quantum wire/insulator/dx2-y2 ＋ idly mixed wave superconductor （q/I/dx2-y2 ＋ idly） junctions. That is different from the case in d- and p-wave superconductor junctions. When the angle α between a-axis of the dx2-y2 wave superconductor and the interface normal is π/4, there follows a rather distinctive tunnelling conductance. The zero-bias conductance peak （ZBCP） may or may not appear in the tunnelling conductance. Both the interface potential z and the quasi-particle lifetime factor F are smaller, there is no ZBCP. Otherwise, the ZBCP will appear. The position of bias conductance peak （BCP） depends strongly on the amplitude ratio of two components for dx2-y2 ＋ idxy mixed wave. The low and narrow ZBCP may coexist with the BCP in the tunnelling conductance. Using those features in the tunnelling conductance of q/I/dx2-y2 ＋ idxy junctions, it can distinguish dx2-y2 ＋ idxy mixed wave superconductor from d- and p-wave one.

Tunneling Conductance in Quantum-Wire/Ferromagnetic-Insulator/d-Wave Superconductor Junction

We have studied the quasiparticle transport in quantum-wire /ferromagnetic-insulator/d wave super- conductor Junction （q/FI/d） in the framework of the Blonder-Tinkham-Klapwijk model. We calculate the tunneling conductance in q/FI/d as a function of the bias voltage at zero temperature and finite temperature based on Bogoliubov- de Gennes equations. Different from the case in normal-metal/insulator/d wave superconductor Junctions, the zero-bias conductance peaks vanish for the single-mode case. The tunneling conductance spectra depend on the magnitude of the exchange interaction at the ferromagnetic-insulator.

Effect of Conduction Pre-heating in Au-Al Thermosonic Wire Bonding

This paper presents the recent study by investigating the vital responses of wire bonding with the application of conduction pre-heating. It is observed through literature reviews that, the effect of pre-heating has not been completely explored to enable the successful application of pre-heating during wire bonding. The aim of wire bonding is to form quality and reliable solid-state bonds to interconnect metals such as gold wires to metalized pads deposited on silicon integrated circuits. Typically, there are 3 main wire bonding techniques applied in the industry;Thermo-compression, Ultrasonic and Thermosonic. This experiment utilizes the most common and widely used platform which is thermosonic bonding. This technique is explored with the application of conduction pre-heating along with heat on the bonding site, ultrasonic energy and force on an Au-Al system. Sixteen groups of bonding conditions which include eight hundred data points of shear strength at various temperature settings were compared to establish the relationship between bonding strength and the application of conduction pre-heating. The results of this study will clearly indicate the effects of applied conduction pre-heating towards bonding strength which may further produce a robust wire bonding system.

Effective thermal conductivity of wire-woven bulk Kagome sandwich panels

Thermal transport in a highly porous metallic wire-woven bulk Kagome （WBK） is numerically and analytically modeled. Based on topology similarity and upon introducing an elongation parameter in thermal tortuosity, an idealized Kagome with non-twisted struts is employed. Special focus is placed upon quanti- fying the effect of topological anisotropy of WBK upon its effective conductivity. It is demonstrated that the effective conductivity reduces linearly as the poros- ity increases, and the extent of the reduction is significantly dependent on the orientation of WBK. The governing physical mechanism of anisotropic thermal transport in WBK is found to be the anisotropic thermal tortuosity caused by the intrinsic anisotropic topology of WBK.

Influence of RE on Ageing Precipitate Characteristics and Softening Resistance of Copper Alloys Contact Wire

The effect of RE （such as Ce, Y and mixed Ce ＋ Y, etc） on ageing precipitate, characteristics and softening resistance of Cu-Cr-Zr alloys contact wire used in electrical railway were investigated in this paper. The results show that the tested Cu-Cr-Zr alloy with trace RE addition could attain higher microhardness and lower electrical conductivity to some extent after being soluted at 950 ℃ for 1 h and aged at 480 ℃. The precipitation process of secondary phase could be accelerated by cold working before ageing treatment which resulted in ageing hardening. Aged at 480 ℃ after 60% cold working, the values of electrical conductivity and microhardness improved significantly compared with that without deformation. The mixed RE （Ce ＋ Y） improved the softening resistance substantially in these trace RE additions, which could increase the soften temperature by 45 ℃.

The Flow Measurement of Multiphase Flow Based on the Conductance Sensor

Oil-gas-water three-phase flow in the pipe is commonly encountered in the petroleum and nature gas industry. Its flow patterns are complex and always changeable, so it’s difficult to be measured and is becoming one of the most important subjects. Moreover, most of the oil fields in China are in such a high water fraction period that measures must be taken to meet the needs of the actual production. A conductance sensor which is widely used in the measurements of oil-water two-phase flow is used to measure the flow rate of the three-phase flow based on the research of the characteristics and the correlation theory, and a new technical solution which is suitable for measuring the oil-gas-water three-phase flow is established. A series of tests demonstrate that it’s feasible to use the conductance sensor in the measurements of oil- gas-water three-phase flow.

A composite sphere assemblage model for porous oolitic rocks:Application to thermal conductivity

The present work is devoted to the determination of linear effective thermal conductivity of porous rocks characterized by an assemblage of grains(oolites) coated by a matrix. Two distinct classes of pores, i.e.micropores or intra oolitic pores(oolite porosity) and mesopores or inter oolitic pores(inter oolite porosity), are taken into account. The overall porosity is supposed to be connected and decomposed into oolite porosity and matrix porosity. Within the framework of Hashin composite sphere assemblage(CSA)models, a two-step homogenization method is developed. At the first homogenization step, pores are assembled into two layers by using self-consistent scheme(SCS). At the second step, the two porous layers constituting the oolites and the matrix are assembled by using generalized self-consistent scheme(GSCS) and referred to as three-phase model. Numerical results are presented for data representative of a porous oolitic limestone. It is shown that the influence of porosity on the overall thermal conductivity of such materials may be significant.

DETERMINATION OF THERMAL CONDUCTIVITY FOR PARTICULATE MATERIALS

A modified hot wire method was applied to measure the thermal conductivity of different kinds of parti culate materials. With a cylindrical device, a heating rod and two thermocouples, the measurement can be finished within several minutes. Compared with the reference data, the results obtained from the measurements were quite reasonable.

Thermal conductance in a two-slit quantum waveguide

Using the scattering-matrix method, we investigate the thermal conductance in a two-slit quantum waveguide at low temperature. The results show that the total thermal conductance decreases monotonically with temperature increasing. Moreover, we find that the behaviours of the thermal conductance versus temperature are different for different types of slits.

Analysis of Nonequilibrium Transport Properties of Interacting Quantum Wire Models

We analyze nonequilibrium electronic transport properties of a typical interacting three-site quantum wire model within Hartree-Fock approximation making use of Keldysh formalism. Some rigorous formulas are provided for direct calculations when Coulomb repulsion is present. According to numerical calculations using above formulas, we investigate the conductance, transport currents, and on site electronic charges of the wire on some special occasions in the interacting case, and also compare them with the results in the noninteracting case.

Numerical and experimental evaluation for density-related thermal insulation capability of entangled porous metallic wire material

Entangled porous metallic wire material(EPMWM)has the potential as a thermal insulation material in defence and engineering.In order to optimize its thermophysical properties at the design stage,it is of great significance to reveal the thermal response mechanism of EPMWM based on its complex structural effects.In the present work,virtual manufacturing technology(VMT)was developed to restore the physics-based 3D model of EPMWM.On this basis,the transient thermal analysis is carried out to explore the contact-relevant thermal behavior of EPMWM,and then the spiral unit containing unique structural information are further extracted and counted.In particular,the thermal resistance network is numerically constructed based on the spiral unit through the thermoelectric analogy method to accurately predict the effective thermal conductivity(ETC)of EPMWM.Finally,the thermal diffusivity and specific heat of the samples were obtained by the laser thermal analyzer to calculate the ETC and thermal insulation factor of interest.The results show that the ETC of EPMWM increases with increasing temperature or reducing density under the experimental conditions.The numerical prediction is consistent with the experimental result and the average error is less than 4%.

Conductive Channel for Energy Transmission

Laser spark obtained by using a conical optics is much more appropriate to form conducting channels in atmosphere. Only two types of lasers are actively considered to be used in forming high-conductivity channels in atmosphere, controlled by laser spark： pulsed sub-microsecond gas and chemical lasers （CO2, DF （deuterium fluoride））, short pulse solid-state and UV （ultraviolet） lasers. Main advantage of short pulse lasers is their ability in forming of super long ionized channels with a characteristic diameter of- 100 mm in atmosphere along the beam propagation direction. At estimated electron densities below 1,016 cm3 in these filaments and laser wavelengths in the range of 0.5-1.0 mm, the plasma barely absorbs laser radiation. In this case, the length of the track composed of many filaments is determined by the laser intensity and may reach many kilometers at a femtosecond pulse energy of-100 mJ. However, these lasers could not be used to form high-conductivity long channels in atmosphere. The ohmic resistance of this type a conducting channels turned out to be very high, and the gas in the channels could not be strongly heated （〈 1 J）. An electric breakdown controlled by radiation of femtosecond solid-state laser was implemented in only at a length of 3 m with a voltage of 2 MV across the discharge gap （670 kV/m）. Not so long ago scientific group from P.N. Lebedev physical institute has improved that result, the discharge gap （-1m） had been broken under KrF laser irradiation when switching high-voltage （up to 390 kV/m） electric discharge by 100-ns UV pulses. Our previous result -16 m long conducting channel controlled by a laser spark at the voltage -3 MV was obtained more than 20 years ago in Russia and Japan by using pulsed CO2 laser with energy -0.5 kJ. An average electric field strength was 〈 190 kV/m. It is still too much for efficient applications.

连续浇铸复合铸造法制备铝包钢双金属导线

针对包覆焊接法制备铝包钢线工艺复杂、能耗大的缺点,采用连续浇铸复合铸造法制备了铝包钢线,并系统性地研究了浇铸温度对铝包钢线两相结合面的显微组织演变及复合材料性能(硬度、导电率、密度)的影响.结果表明:当浇铸温度为820℃时,在铝和铁两相的界面结合处形成的扩散带中,Fe的质量分数为40.3%,Al的质量分数为59.7%,两相结合生成Fe_(2)Al_(5),此时铝包钢线的性能达到最佳,两相界面结合处的显微硬度(HV)为204,样品电导率为53.23%IACS(国际退火铜标准),密度为4.36 g/cm^(3).

纳米银线导电膜在电子设备中的应用

本文详细探讨了纳米银线导电膜的制备方法、性能研究以及在电子设备中的应用;详细描述了导电膜的制备过程,包括涂布、干燥和热压等步骤;分析了纳米银线导电膜的性能,包括导电性能、透明度和柔韧性。此外,探讨了纳米银线导电膜在电子设备中的应用,包括在透明柔性电路、柔性电极以及其他电子设备中的应用。并对纳米银线导电膜的未来展望进行了探讨。