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The off-line discharge between the pantograph and catenary (PAC) occurs frequently in the actual operation of an electric locomotive, which affects the quality of the received current and the service life of the pantograph. The current experiments on the off-line discharge between the PAC are mainly low-power ones and the models established are static. To study the electrical behaviors during the PAC relative motion under the actual working conditions, in this paper, the voltage and current of the contact wire (CW) during its motion are measured. And the electrical behaviors during the rise, fall and reciprocating motions of the pantograph are investigated by combining a finite element method (FEM) model based on the magnetohydrodynamics with the auto transformer (AT) traction network circuit and moving mesh method. It is found that the harmonic frequencies are mainly in the range of 0-30 MHz. The voltage distortion is more obvious during the fall of the pantograph. And the negative polarity spike pulse has a larger amplitude and occurs more frequently. The novelty of this paper lies in the experimental test with the high current and high power, as well as the systematic analysis of the electrical behaviors and multi-physical field evolution during the motion of the pantograph under the working conditions. Its contribution is to present an effective method to study the dynamic behaviors of the PAC. The research results can provide an important reference for the identification of the electrical characteristics of the PAC and the protection of the PAC equipment.

Owing to the variation between lithium-ion battery (LIB) cells, early discharge termination and overdischarge can occur when cells are coupled in series or parallel, thereby triggering a decrease in LIB module performance and safety. This study provides a modeling approach that considers the effect of cell variation on the performance of LIB modules in energy storage applications for improving the reliability of the power quality of energy storage devices and efficiency of the energy system. Ohm's law and the law of conservation of charge were employed as the governing equations to estimate the discharge behavior of a single strand composing of two LIB cells connected in parallel based on the polarization properties of the electrode. Using the modeling parameters of a single strand, the particle swarm optimization algorithm was adopted to predict the discharge capacity and internal resistance distribution of 14 strands connected in series. Based on the model of the LIB strand to predict the discharge behavior, the effect of cell variation on the deviation of the discharge termination voltage and depth of discharge imbalance was modeled. The validity of the model was confirmed by comparing the experimental data with the modeling results. [ABSTRACT FROM AUTHOR]

Owing to the variation between lithium-ion battery (LIB) cells, early discharge termination and overdischarge can occur when cells are coupled in series or parallel, thereby triggering a decrease in LIB module performance and safety. This study provides a modeling approach that considers the effect of cell variation on the performance of LIB modules in energy storage applications for improving the reliability of the power quality of energy storage devices and efficiency of the energy system. Ohm’s law and the law of conservation of charge were employed as the governing equations to estimate the discharge behavior of a single strand composing of two LIB cells connected in parallel based on the polarization properties of the electrode. Using the modeling parameters of a single strand, the particle swarm optimization algorithm was adopted to predict the discharge capacity and internal resistance distribution of 14 strands connected in series. Based on the model of the LIB strand to predict the discharge behavior, the effect of cell variation on the deviation of the discharge termination voltage and depth of discharge imbalance was modeled. The validity of the model was confirmed by comparing the experimental data with the modeling results.

In this study, high-density La 0.67 Ca 0.27 Sr 0.06 MnO 3 (LCSMO) ceramics were successfully obtained by sol-gel method followed by cold isostatic pressing (CIP) under 250 MPa. Effects of sintering temperature (T S , 1250 °C ≤ T S ≤ 1450 °C) on structure, surface chemical, electrical, and optical properties of as-obtained LCSMO ceramics were investigated by X-ray diffraction (XRD, BDX3200), X-ray photoemission spectroscopy (XPS, Thermo Fisher Scientific), a four-probe system (East changing ET9005), Fourier transform infrared spectrometry (FTIR, TENSOR 27), Raman microscopy (RENISHAW inVia) and UV–vis spectrophotometry (HITACHI U-4100), respectively. All prepared samples showed orthorhombic structure with Pnma space group. As T S increased, grain size gradually rose from 2.71 to 7.30 μm. XRD refinement, Raman, and FTIR all depicted constant of bond angle and length of Mn–O. Hence, variation in T S did not cause lattice distortion inside samples. The best electrical properties were obtained at 1450 °C, where resistivity (ρ) fell below 0.008 Ω cm and temperature coefficient of resistivity (TCR) reached 13.0% K−1 at 289.2 K (room temperature).It is worth noting that electrical performance was indeed improved due to high densities of samples under processing of CIP. Overall, the change in T S from 1250 to 1450 °C greatly influenced electrical behaviors but showed little effect on structural and optical properties of LCSMO ceramics. [ABSTRACT FROM AUTHOR]

Phase change memory (PCM) based on chalcogenide compounds is considered to be an excellent candidate for next-generation memory because of its high speed, low energy consumption, high-density information storage, and durable stability. This has become a topic of general interest during the last two decades. Various systems have been proposed to explore more suitable compositions for PCM applications such as Ge-Te and Sb-Te binary alloys, GeTe-Sb2Te3 pseudo-binary alloys, and novel Te-free Sb-based alloys. In spite of this, the comprehensive performance of these pure systems still cannot fully satisfy the need for commercialization. Modification of alloys is an effective approach to enhance performance; this has been investigated significantly. Nevertheless, there are relatively few reports that directly provide integrated data on the effect of various alloying modifiers on the properties of PCM materials to obtain the relevant information conveniently, understand the role of chemical tailors on the properties of PCM materials deeply, and select modifiers matching the matrix systems efficiently. To achieve these goals and facilitate studies on PCM materials, this overview begins by summarizing and analyzing the role of alloying tailors on the performance of representative GeTe, Sb2Te3, Ge2Sb2Te5, and Sb-based systems containing Te (Sb2Te, Sb3Te, Sb4Te) and without Te (Sb-M), followed by comparing the comprehensive performance of optimized systems. [ABSTRACT FROM AUTHOR]

Abstract: The mechanisms of metal phase transition process during electrical explosion are experimentally and theoretically investigated. Past experiments of investigation are single metal foil, such as gold, aluminum, and copper. The characteristics of aluminum‐nickel (Al/Ni) multilayer foil were investigated, which means electrical behavior and energy output. The foil was fabricated by magnetron sputtering based on ceramic substrate, and lithographically patterned into bow‐tie bridge regions. Scanning electron microscopy characterization revealed the layer structure of the Al/Ni multilayer. X‐ray diffraction characterization was employed to ascertain the composition of Al/Ni. The probing of voltage‐current waveforms reveals that Al/Ni multilayer foils exhibit high voltage, short burst time and high absorbing energy in electrically heated in comparison with copper or nickel alone. We also measured the energy output of foils through velocity measurements of encapsulation layers ejected from bridge region by Photonic Doppler velocimetry. We observed flyer velocities from Al/Ni multilayer foil in the 1.6–2.9 km/s range, which is much higher than copper foil. Combined with the 1‐D non‐stationary acceleration model calculation, it is found that the chemical energy and increased electrical absorbing energy contributed to additional kinetic energy in the 40–80 mJ range. [ABSTRACT FROM AUTHOR]

The 3-acetamido propyl acrylate [AcAPA] (monomer) was synthesized. The homopolymerization of AcAPA was carried by normal free radical polymerization procedure within tetrahydrofuran at 60 oC using AIBN as the initiator. The poly(AcAPA) composites embedded europium(III)chloride (EuCI3) were prepared. Dependent of temperature and frequency on the dielectric characteristics were investigated in a frequency range starting from 100 Hz to 20000 Hz and in a temperature range from 243 K to 333 K. The results showed that the dielectric loss and dielectric constant increased, and the highest dielectric values were estimated in the case of poly(AcAPA) composites loaded EuCI3 and graphite as well. The FT-IR results indicated that the structural characterization of poly(AcAPA) is strongly affected by the incorporation of EuCI3. Thermal analysis results show that the thermal stability of the EuCI3-doped poly(AcAPA) composites has improved compared to the pure poly(AcAPA). The thermal property of composites has improved significantly due to an increasing in filler loadings showing that a good coordination exists between EuCI3 particles and poly(AcAPA). The dielectric constants of poly(AcAPA)/EuCI3 composites have significantly improved with comparatively low dielectric loss values, indicating that the composites can be considered as a crucial material for embedded capacitor applications. Electrically conducting graphite-based poly(AcAPA)/EuCI3 composites were prepared and the surface morphology of polymer composites were characterized by SEM micrographics. Also, the dc electrical conductivities of graphite-based poly(AcAPA)/EuCI3 were investigated. [ABSTRACT FROM AUTHOR]

A versatile template-assisted strategy for the preparation of monodispersed rattle-type hybrid nanospheres, encapsulating a movable Au nanocore in the hollow cavity of a hairy electroactive polymer shell (Au@air@PTEMA- g-P3HT hybrid nanorattles; PTEMA: poly(2-(thiophen-3-yl)ethyl methacrylate; P3HT: poly(3-hexylthiophene), was reported. The Au@silica core-shell nanoparticles, prepared by the modified Stöber sol-gel process on Au nanoparticle seeds, were used as templates for the synthesis of Au@silica@PTEMA core-double shell nanospheres. Subsequent oxidative graft polymerization of 3-hexylthiophene from the exterior surface of the Au@silica@PTEMA core-double shell nanospheres allowed the tailoring of surface functionality with electroactive P3HT brushes (Au@silica@PTEMA- g-P3HT nanospheres). The Au@air@ PTEMA- g-P3HT hybrid nanorattles were obtained after etching of the silica interlayer by HF. The as-prepared nanorattles were dispersed into an electrically insulating polystyrene matrix and for the first time used to fabricate nonvolatile memory devices. As a result, unique electrical behaviors, including insulator behavior, write-once-read-many-times and rewritable memory effects, and conductor behavior as well, were observed in the Al/Au@air@PTEMA- g-P3HT+PS/ITO (ITO: indium-tin oxide) sandwich thin-film devices. [ABSTRACT FROM AUTHOR]