Molecular dynamics simulation of a relativistic gas: Thermostatistical properties

Studying special relativistic generalizations of classical thermodynamic systems have recently attracted much attention despite its long and controversial history. Here, we propose a relativistic model of a realistic dilute gas which can easily be studied using standard molecular dynamics simulations. We briefly outline some of its thermostatistical properties which help resolve controversial issues in relativistic thermodynamics. In particular, we find that Jüttner function is the correct generalization of Maxwell–Boltzmann velocity distribution. We also conclude that relativistic temperature is best understood as a rest-frame-property, invariant under various relativistic transformations, i.e. Lorentz transformation and time reparametrization. Finally, we provide canonical non-equilibrium simulations of such systems and study the effects of a temperature gradient imposed by heat reservoirs.     

Layered molybdenum disulfide coated carbon hollow spheres synthesized through supramolecular self-assembly applied to supercapacitors

Through supramolecular assembly method, molybdenum disulfide (MoS₂) is uniformly anchored on the mesoporous hollow carbon spheres (HCS), which are obtained by hard template method. The introduction of HCS can prevent the agglomeration of MoS₂ and decrease the electric resistance of the compound material MoS₂@HCS. The composite of MoS₂@HCS-17 also owns a specific surface area of 119.0 m² g⁻¹. For MoS₂@HCS-17, SEM and TEM results exhibit that flaky MoS₂ is uniformly covered on hollow carbon spheres and possesses an expanded layered structure. Electrochemical test results show that MoS₂@HCS-17 can reach 314.5F g⁻¹ at 1A g⁻¹. When tested at a scan speed of 50 mV s⁻¹_, there is still 87% specific capacity retention for MoS₂@HCS-17 after 4000 cycles. Moreover, the assembled MnO₂//MoS₂@HCS asymmetric supercapacitor manifests 34.0 Wh kg⁻¹ at 611.6 W kg⁻¹. Bending by 180°, our assembled device still keeps stable capacitive performance. This asymmetric supercapacitor also keeps almost 93% capacity maintained after 2000 cycles.     

Synthesis and acetone gas sensing properties of Ag activated hollow sphere structured ZnFe2O4

Sheet stacked ZnFe₂O₄ hollow spheres have been synthesized through a simple hydrothermal method using Zn(CH₃COO)₂ and Fe(NO₃)₃ as Zn and Fe sources, respectively. Then a series of Ag activated ZnFe₂O₄ composites are prepared. XRD patterns demonstrate that the as-synthesized powders are pure ZnFe₂O₄. FE-SEM images exhibit that the as-synthesized Ag-ZnFe₂O₄ particles are spherical with the diameter of 800–1000?nm. TEM images demonstrate that the as-synthesized Ag-ZnFe₂O₄ are hollow sphere structure. The gas sensing tests show that 0.25?wt% Ag-ZnFe₂O₄ has the highest responses to 100?ppm acetone vapor at 175?°C, and response time and recovery time are 17 and 148?s respectively. In addition, 0.25?wt% Ag-ZnFe₂O₄ has a good selectivity to acetone. Ag activated ZnFe₂O₄ composites exhibit excellent acetone gas sensing properties and gives potential for the detection of acetone vapor in the application of practical industrial processes and health control.     

Character‐contrast measurements on reflective displays using replica masks

Abstract— A replica‐mask method is presented to measure the contrast of character strokes on reflective displays. The method accounts for veiling glare introduced into the detector by the bright areas surrounding the dark characters. A sampling sphere is employed to provide a uniform diffuse surround. Measurements of the diffuse reflectances are provided with specular included and with specular excluded. For reflective displays, the contrast is the same as the ratio of the reflectances and does not scale with illuminance levels. Details are provided to replicate the measurement procedure.     

中空NiO微球的微波水热制备及其表征

以六水合硝酸镍为镍源,聚乙烯吡咯烷酮（PVP）为表面活性剂,采用微波辅助水热方法制备前驱体α-Ni（OH）2,经过500℃热处理之后得到具有中空微纳结构NiO粉体。以XRD、SEM、TEM、UV-Vis测试手段,对样品进行了分析,并对其电化学性能进行初步的测试。结果表明合成的样品为立方晶系的NiO,其结构为中空球形。C-V曲线表明了样品具有典型的法拉第准电容,可逆性良好,具有良好的电化学稳定性。     

High-porosity mullite ceramic foams prepared by selective laser sintering using fly ash hollow spheres as raw materials

A novel method to prepare high-porosity mullite ceramic foams by selective laser sintering (SLS) using fly ash hollow spheres (FAHSs) as raw materials was reported. The complex-shaped FAHS green bodies and ceramic foams without delamination or cracks were prepared by SLS. The influence of sintering temperatures on linear shrinkage, phase composition, porosity and mechanical properties was investigated. With the increase of sintering temperature from 1250?°C to 1400?°C, the compressive strength of ceramic foams increased from 0.2?MPa to 6.7?MPa causing the fracture mechanism change from fracturing along FAHSs to across FAHSs, while the porosity of ceramic foams decreased from 88.7% to 79.9% which was higher than those of ceramic foams prepared by the conventional methods. The relatively high porosity of ceramic foams was resulted from the inner hollow structure of FAHSs, the interspaces between stacking FAHSs, and the gaps between FAHSs directly related to SLS. The results above indicated that the fabrication of high-porosity FAHS ceramic foams by SLS could achieve the advanced utilization of FAHS solid waste.     

Spherical mesophase soft carbon materials with micro-nano composite structure and their applications in lithium-ion batteries

This paper is to investigate the mesophase sphere soft carbon material with micro-nano composite structure and its application in the energy-storage Li-ion battery and electrochemical performance of the battery through experimental tests. The results show that the ball diameter is below 10 μm. For button half-cell, the first coulombic efficiency at 0.1C rate is about 87.1%, the ratio that charging capacity of 2C divided by the charging capacity of 1C is 84.8%, and the charging capacity retention rate after 50 cycles at 0.5C rate is 99.9%. For a full battery of 50 Ah, the discharge capacity can still maintain at 80% or more at the 2C or 3C discharging rate, its discharge rate can still reach more than 80% at a temperature of ?20℃, and the capacity retention is 97.7% after 500 cycles.     

Modeling the bagging behavior of worsted fabrics using response surface methodology

In this paper, we have studied the effect of a number of loading cycles on fabrics bagging behavior, and then investigated the influence of factors such as sample weight, test speed, and sphere diameter on the worsted fabrics bagging behavior using response surface method (RSM). Six worsted fabric types with different weights were prepared and then the bagging properties of these fabrics were measured using a newly developed test method. Bagging parameters including bagging force, work, fatigue, resistance, hysteresis, and residual height are calculated. Then, a statistical model (RSM) was used for the experimental plan (with these factors) to determine the runs of an experiment (or selected points). The experimental results showed that sample weight and sphere diameter have a significant effect while test speed has no significant effect on the bagging parameters. Also, the fitted models of bagging parameters are obtained and coefficient effects are estimated.     

带MVG和MSMG的5×5全长棒束单相流场和温度行为数值分析

定位格架作为燃料组件的关键部件之一，直接影响到燃料组件的热工性能。本文对带结构格架（MVG）和跨间搅混格架（MSMG）的5×5全长加热棒束单相流场和温度场采用计算流体力学（CFD）程序进行数值分析研究，获得该特征棒束组件出口二次流场以及温度场分布特性。研究表明，定位格架下游流场受定位格架和距离的影响，定位格架上游流场对下游二次流几乎无影响，定位格架导致流体强烈的横向二次流，增强了流体和加热棒之间的换热能力，使得棒束子通道截面流体温度更加均匀。与5×5全长棒束出口子通道温度的实验数据对比分析表明，获得的计算模型可以较好地分析该型棒束组件结构温度场行为。      

Enhanced electrochemical performance of nickel hydroxide electrode with monolayer hollow spheres composed of nanoflakes

Nickel hydroxide electrodes with hollow spheres were fabricated using a PS (polystyrene) sphere template and electrochemical deposition. The nickel hydroxide grew perpendicular to the electrode substrate during anodic deposition and around the PS spheres during cathodic deposition. After the removal of the PS template, hollow spheres or open hollow spheres were formed via cathodic deposition. The nickel hydroxide electrode with hollow spheres and nanoflakes showed greatly enhanced electrochemical performance in alkaline solution compared with the bare nickel hydroxide electrode. The opening of the hollow spheres facilitated easy electrolyte transport to the reaction sites and led to a further increase in the specific capacitance of the nickel hydroxide electrode. The specific capacitance of the electrode with the open hollow spheres reached 800 F g⁻¹, which was much higher than that of the bare electrode (224 F g⁻¹) and the hollow-sphere electrode (342 F g⁻¹) at a discharge current density of 10 A g⁻¹.