SnO2-carbon composites for lithium-ion battery anodes

A SnO₂-carbon composite prepared by heat treating a mixture of colloidal SnO₂ and sucrose demonstrated a reversible lithium storage capacity of 680 mA h/g on the 1st cycle. The discharge curve of the composite did not exhibit the 1.0 V plateau characteristic of SnO₂. The high reversible capacity of the composite suggests that lithium is stored in both tin and carbon. The composite demonstrated reduced capacity fade over SnO₂ as well as SnO:graphite and Sn:graphite composites.     

基于小波分析的自动包装机快速称量系统

目的 随着袋装商品需求的增加,设计一种新型包装机自动称量系统来快速完成称量包装。方法 设计一种基于ARM最小系统的包装机控制系统,其中包括灵敏度为2 mV/V双应变片称量结构、mV级别的数模转换电路和驱动电路等多个部分,并且通过编写称量流程、AD设备驱动和小波变换提取等软件系统,最后利用质量采集和响应对比实验分析系统。结果 实验发现,小波变换提取信号在0.2 ms即可稳定识别的质量为300 g。结论 结果证明所设计的自动包装系统可以稳定实现各类袋式产品的快速称量封装。     

一种新的可扩展用户浏览兴趣表示模型

在分析Web使用挖掘中现有用户浏览兴趣表示方法的特点和不足基础上,针对现有方法表示用户浏览兴趣准确性不高的缺点,提出了一种新的可扩展用户浏览兴趣表示模型（SIM）,并且给出了SIM的数据结构、SIM表示用户浏览兴趣的方法。以真实数据进行了实验分析,实验结果表明,SIM与现有方法相比有效地提高了表示用户浏览兴趣的准确性。     

Flame dynamics in a vented vessel connected to a duct: 1. Mechanism of vessel-duct interaction

The paper presents a parametric experimental study of explosion initiated in a vessel and vented through a duct. The aim is to clarify the mechanism of the vessel-duct mutual interaction during explosion and its role in determining the overpressure in the vessel. For a vessel of fixed size, the chosen parameters are the diameter and length of the discharge duct and the profile of area change between the vessel and the duct.Results with a stoichiometric propane-air mixture demonstrate that the change of the combustion regime inside the vessel, responsible for augmented overpressure, is driven by an impulse generated in the initial part of the duct (during an explosion-like combustion) shortly after the flame penetrates into it. The origin of the impulse is discussed. Increasing the duct/vessel diameter ratio or using the profiled vessel-duct passage weakens the generated impulse (decreases its pressure and velocity amplitudes) but at the same time generates higher subsequent pressure rise in the vessel. This implies that enhancement of the explosion overpressure in the vessel is unavoidable in this type of venting.     

开放环境下激光内送粉熔覆TC4钛合金的氧化行为

目的研究开放环境下激光熔覆TC4钛合金的氧化行为。方法采用激光内送粉熔覆技术制备了不同氩气流量下的TC4钛合金熔覆涂层,通过SEM、EDS和XRD分析了不同氩气流量下涂层氧化层的表面和横截面微观形貌、微观组织、元素分布和物相组成,通过维氏硬度计分析涂层的显微硬度。结果随着氩气流量的减小,涂层表面颜色逐渐变深,由银白色依次变成黄色、蓝色、深灰色。XRD分析表明,颜色的变化与有色氧化物有关,黄色氧化层主要为黄色TiO,蓝色氧化层主要为蓝色Ti2O3,深灰色氧化层主要为白色TiO2,呈现深灰色与厚的氧化层结构有关。无氩气保护下的涂层表面粗糙,氧化层为厚而疏松多孔结构,与涂层存在缝隙;有氩气保护且随着氩气流量的增加,涂层表面变得光滑,氧化层厚度逐渐减小,致密性好,且与涂层结合良好。随着氩气流量的增加,组织由板条状转变成针状,这主要与冷却速率有关。当涂层颜色为蓝色时,涂层硬度变高,说明氧扩散深度大且氧含量多。结论在不同的氩气流量下,熔覆涂层表面形成多种不同氧化色。蓝色可作为可接受和不可接受氧化程度的临界颜色。     

Temperature dependence of the photovoltaic characteristics of silicon MIS solar cells

Temperature dependence of dark and illuminated current-voltage characteristics and other major solar cell parameters of AlSiO_xpSi structure are reported in the range 100–300 K. The capacitance-voltage measurements indicated that the pSi surface of the MIS cell remains inverted throughout this range of temperatures. Temperature coefficients of the open circuit voltage, the short circuit current, the fill factor, and the efficiency of the MIS solar cells are presented. The coefficients of the MIS cells closely resemble those of n⁺ pSi cells.     

三角帆蚌贝壳的微结构及尺寸变化特征

天然生物经历了亿万年的不断进化,已经形成了近乎完美的结构。天然生物材料结构的研究是仿生研究的基础,本文以三角帆蚌贝壳为研究对象,利用SEM和AFM,描述了三角帆蚌贝壳的微结构特征,包括其角质层、棱柱层、珍珠层及界面和晶带的形貌,揭示文石晶片及各层间的尺寸变化规律。研究表明:角质层内部分布大量裂纹,珍珠层与棱柱层无明显过渡界面,珍珠层内发现条状晶带结构缺陷;贝壳壳体和珍珠层厚度随0生长线向外呈现先增大后减小的变化趋势,且单层文石晶片的厚度不均,最厚处可达最薄处的2倍多。对三角帆蚌贝壳的结构进行了深入研究,为其优异的力学性能提供了理论依据,为未来的仿生结构设计提供了新思路和新想法。      

基于AHP的云存储负载均衡研究

针对云存储系统节点在数据分布策略和系统响应时间方面的综合负载计算问题,提出了一种云存储系统的负载均衡算法,并对该算法进行了验证。算法基于层次分析法（Analytic Hierarchy Process,AHP）,通过建立综合评估指标体系,从可用存储空间、可用CPU、可用内存和访问热度四个方面,计算各个存储节点的综合负载,并据此对数据存取进行均衡调度。验证结果表明,通过调整不同指标的权重,算法能够很好地满足不同的应用需求,同时,该算法能够很好地反应各节点的综合负载,实现云存储系统整机性能的优化,尤其适用于一些高并发的大数据存储。     

Annealing induced shrinkage-fill effect of tungsten‑potassium alloys with trace titanium doping

The shrinkages presented in sintering process of tungsten alloys are extremely detrimental to their practical applications in fusion reactors. Positively in this work, we effectively reduced the shrinkages via synergistically applying Ti-doping and annealing process on tungsten‑potassium (WK) alloys. This shrinkage-fill effect only works in the one with trace amount of titanium doping, such as 0.05 wt%Ti or 0.5 wt%Ti. Due to such effect, the compressive strength was improved by ~18%. Based on morphological and elementary analyses, we speculated that the Ti-rich particles along the grain boundaries of WK alloys were activated and migrated into shrinkages during annealing. Further Ti doping (e.g. 1wt.%Ti) led to nanoscale grain refinement in WK alloys, which almost doubled the compressive strength. In this case, an unconventional grain-refinement model was proposed. Furthermore, anomalous grain growth was observed in WK-3wt.%Ti, which was attributed to the formation of Ti-rich regions and the corresponding raise of energy in grain boundaries. The fabricating strategies in this work may benefit the design of refractory tungsten alloys with less shrinkages and ultra-fine grains.