电化学浸渍法制备空间氢镍电池用镍电极的循环寿命研究

以空间储能电源4.5’镍极板为对象,研究了过充电、高倍率及极板孔径对电化学浸渍电极循环寿命的影响.结果表明,5C过充电70%,电极初始容量为2.7 Ah,150次循环后容量逐渐下降,300次循环,放电容量约为1.7 Ah(保持率约63%).5C无过充电,300次循环其容量保持率约100%,1000次循环,容量保持率仍可达76%.无过充电,极板孔径及小电流活化均可改善电极循环性能.     

Correlation of Oscillation Cycles and Crystallization in HDPE Blends with Small Amounts of HMWPE Prepared by Dynamic-Packing Injection Molding

The effect of oscillation cycles on crystal morphology was investigated for high-density polyethylene (HDPE) in blends with 4 wt% high molecular weight polyethylene (HMWPE) (labeled B4) in samples prepared through dynamic-packing injection molding (DPIM). With the aid of differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), a weblike shish-kebab morphology that markedly increased stiffness and toughness was found at a specific oscillation cycle. The DSC and SEM results showed that crystal morphology was altered with changes in the oscillation cycle. The SEM and TEM results showed that a much better weblike shish-kebab structure, in which most of the lamellae connect different columns compared with conventional shish-kebabs, was formed in the B4 samples when the oscillation cycle was 10s. These results show that a proper oscillation cycle favors the improvement of crystal structures in HDPE blends induced by a small amount of HMWPE.     

Modelling of hysteresis loops taken during the stress- and temperature-induced martensitic transformations

In this article, it has been shown that the process of reconfiguration of the crystal defects system noticeably contributes to the width of the stress–strain and strain–temperature hysteresis loops taken during the stress- and temperature-induced martensitic transformations of the shape memory alloys. It has been demonstrated that the contribution of the defects system to the hysteresis width strongly depends on the alloy temperature and the transformation cycle duration. It has been shown that the hysteresis effect can be observed not only in the course of the first-order phase transition of martensitic type, but also in the course of the gradual deformation of crystal lattice. The obtained results are applicable to the ferroelastic phase transitions in the different crystalline solids.     

Electron scattering studies of DMS,DMDS and DMSO homologous series

The present paper reports ionisation, elastic and total cross section for the first three members of dimethyl sulphide, dimethyl disulphide and dimethyl sulphoxide family of molecules. The multi-scattering centre spherical complex optical potential formalism is applied for integral elastic and inelastic cross section calculations. From the inelastic part, ionisation cross section is derived using complex scattering potential-ionisation contribution method. The total cross section is then obtained from the sum of elastic and inelastic contributions. A reasonably good agreement is obtained for elastic cross section, wherever comparison is available. The ionisation and total cross section calculation for the complete set of molecules has been performed for the first time.     

COMPARISON BETWEEN AQUEOUS POLYMER SOLUTIONS AND WATER AS PHASE CHANGE MATERIAL (PCM) USED FOR COLD TRANSPORT CHAIN

Abstract

The cold chain currently uses aqueous polymer solutions as phase-change material (PCM), which permits it to thaw more slowly than ice. The aim of this work is to study some physical properties of such PCM and to propose an experimental protocol allowing us to compare different PCMs under specific heat transfer conditions. Length of the phase change flat plate during thawing is proposed to compare different PCMs. Investigations on the rheological behavior are also presented. Analysis of the results makes it possible to show that kinetic of phase change is related to the rheological properties of material. The thermal properties thus should not constitute the only physical criterion for the choice of a material.     

ERA-Interim中的中国地区水分循环要素的时空演变特征分析

本文利用1979–2011年欧洲中期天气预报中心 (ECMWF) 的再分析资料 (ERA-Interim), 运用经验正交函数展开 (EOF) 和相似系数等方法, 对中国地区水分循环诸要素的时空特征进行了计算与分析. 研究结果表明: 在空间分布特征上, 蒸发量、纬向水汽通量和经向水汽通量均与大气可降水量的空间分布最相似, 大气可降水量和降水量均与蒸发量的空间分布最相似, 降水量与纬向水汽通量的相似系数略大于其与经向水汽通量的相似系数; 在时间演变上: 年降水量在1979–2002年间, 呈现非常显著的上升趋势; 在2002–2011 年间, 呈现显著的下降趋势. 年蒸发量在该两个时段的变化趋势与年降水量一致, 但均比年降水量明显; 年蒸发量在1979–2011年间呈现非常显著的上升趋势, 其年际变化明显小于年降水量. 可降水量和水汽通量散度在1979–2011年间的长期变化趋势不明显, 但可降水量的年际变化呈阶段式增大, 水汽通量的年际变化一直较大. 纬向与经向水汽通量均存在2–3年为周期的年际变化; 此外, 纬向水汽通量在1979–2011年间还存在显著的下降趋势. 春、秋季的水汽通量都存在显著下降的长期变化趋势, 夏、冬季的长期变化趋势不明显. 四季都存在2–3年为周期的年际变化. 此外, 夏季还存在明显的年代际转折. 关键词： 水分循环 时空特征 EOF 相似系数     

Performance Optimizations with Single-, Bi-, Tri-, and Quadru-Objective for Irreversible Diesel Cycle

Applying finite time thermodynamics theory and the non-dominated sorting genetic algorithm-II (NSGA-II), thermodynamic analysis and multi-objective optimization of an irreversible Diesel cycle are performed. Through numerical calculations, the impact of the cycle temperature ratio on the power density of the cycle is analyzed. The characteristic relationships among the cycle power density versus the compression ratio and thermal efficiency are obtained with three different loss issues. The thermal efficiency, the maximum specific volume (the size of the total volume of the cylinder), and the maximum pressure ratio are compared under the maximum power output and the maximum power density criteria. Using NSGA-II, single-, bi-, tri-, and quadru-objective optimizations are performed for an irreversible Diesel cycle by introducing dimensionless power output, thermal efficiency, dimensionless ecological function, and dimensionless power density as objectives, respectively. The optimal design plan is obtained by using three solution methods, that is, the linear programming technique for multidimensional analysis of preference (LINMAP), the technique for order preferences by similarity to ideal solution (TOPSIS), and Shannon entropy, to compare the results under different objective function combinations. The comparison results indicate that the deviation index of multi-objective optimization is small. When taking the dimensionless power output, dimensionless ecological function, and dimensionless power density as the objective function to perform tri-objective optimization, the LINMAP solution is used to obtain the minimum deviation index. The deviation index at this time is 0.1333, and the design scheme is closer to the ideal scheme.     

Petrarch's canzoniere: Rational addiction and amorous cycles

The paper is concerned with a celebrated collection of love poems, the 14th century Italian poet Francis Petrarch's Canzoniere. A striking feature of these poems is the emotional ups and downs experienced by Petrarch and his platonic mistress Laura. Recently, attempts have been made to model these emotional swings by catastrophe theory or nonlinear differential equations. This paper takes a different approach. Starting with a pair of differential equations that model the dynamics of the emotions of the two individuals, we formulate an optimal control problem. A key hypothesis of this problem is that Petrarch was a rational addict of his desire for Laura. With specific functional forms and parameter values we identify a stable limit cycle that gives a representation of the oscillating emotions of Laura and Petrarch.