保温模块剪力墙住宅体系简介

本重在介绍一种全新的住宅建筑体系—保温模块剪力墙住宅体系，通过与常见住宅体系的比较，指出了保温模块剪力墙住宅体系的广阔发展前景。     

Application of virtual laminated element in the topology optimization of structures

This paper presents the topology optimization design of structures composed of plane stress elements. The authors' proposed method of topology optimization by virtual laminated element is based on the Evolutionary Structural Optimization (ESO) method of linear elasticity, but dose not require formation of as many elements as the conventional ESO method. The presented method has the important feature of reforming the stiffness matrix in generating optimum topology. Calculation results showed that this algorithm is simple and effective and can be applied for topology optimization of structures.     

一种新型桥梁防撞装置的探讨

针对非通航孔桥墩结构单薄,抵抗船舶撞击能力小的现状,本文提出了一种桥墩前新型拦截消能装置.该装置在船撞力作用下,利用"跷跷板"原理,使水平铺置的拦截网旋转成竖立工作状态,能增加阻拦住失控船舶的机率,大大减少了拦截系统被船舶直接压过驶走的概率.后经计算和综合分析效果良好,其成果可为非通航孔防撞设计借鉴参考.     

块对角占优矩阵的特殊应用

以矩阵范数性质的块对角占优矩阵和广义严格对角占优矩阵为工具,利用矩阵分块的方法引入了矩阵非奇异的判定条件,讨论了矩阵非奇异性的判定准则,并利用数值例子说明了所给结论的可行性和有效性．     

绿色消费与我国农业低碳技术推广的路径选择!

农业低碳技术以低能耗、低污染、低排放为基础,绿色消费以有益于人体健康为目的,它们与经济发展并行不悖,与民生问题息息相关,在低碳农业发展中良性互动。在现有技术锁定和路径依赖、低碳农业发展水平和消费者绿色消费行为等瓶颈制约下,打破技术锁定和路径依赖、加快低碳农业发展、联动多方协调力量、倡导绿色低碳,是我国当前绿色消费与农业低碳技术推广的路径选择。     

Landing techniques in volleyball

Abstract

Knee injuries such as anterior cruciate ligament lesions and patellar tendonitis are very frequent in volleyball, and are often attributed to micro traumas that occur during the landing phase of airborne actions. The aim of the present study was to compare different jumping activities during official men's and women's volleyball games. Twelve top-level matches from the Italian men's and women's professional leagues were analysed. The jumps performed during the games were classified according to the landing technique used by the player (left or right foot or both feet together), court position, and ball trajectory. Chi-square analyses were performed to detect differences in landing techniques between the sexes, court positions, and trajectories when serving, attacking, blocking, and setting. Significant differences (P < 0.05) were found between the sexes for block, set, and spike but not for the jump serve. The frequency of landings on one foot was related to court position and the trajectory of the sets: when spiking faster sets, the players were more likely to use a one-footed landing. The present results should help coaches and physiotherapists to devise appropriate training and prevention programmes, and reveal the need for further detailed biomechanical investigations of the relationships between landings and knee injuries.     

阶梯水价对城市居民用水量及低收入家庭福利的影响

城市水资源短缺已然成为中国最严重的环境问题之一。在气候变化及社会经济快速发展的背景下,水资源短缺问题加剧。本文采用2002-2012年中国285个地级市的面板数据,实证分析了递进阶梯水价对中国城市居民生活用水影响。计量结果表明,在统一水价制度框架下,水价的提高确实能减缓用水短缺,但由于水价缺乏弹性,统一水价调节用水的功能有限。此外,进一步实证研究显示,已实施阶梯水价的城市比统一水价的城市能减少16.58%水消耗。除价格因素之外,实证发现,居民家庭人均可支配收入、家庭总人口数、从业人员数占比、年均降雨量以及年平均气温导致了家庭水消耗增加,而受教育程度和人口的聚集导致家庭水使用量减少。以此为基础,本文设计了四级阶梯水价。通过构建非线性预算约束的家庭经济模型以及家庭福利分析,结果发现,采用四级阶梯水价比国家发改委（NDRC）的三级阶梯水价不仅能提高水资源使用效率,而且预测得知可提高低收入家庭福利为107.6元。     

6轮ARIA的最优不可能差分分析

研究了ARIA在不可能差分分析下的安全性.通过对算法扩散层的分析,给出了ARIA中间状态在加密过程的差分传递性质.在此基础上证明了6轮ARIA不存在使得输入输出差分重量小于10的不可能差分路径,同时证明了在输入输出差分重量为10的情况下6轮ARIA只存在2类形式的不可能差分路径.利用构造出的这2类不可能差分路径,从理论上证明了6轮ARIA不可能差分攻击的最优结果为:2¹²⁰个选择明文和2^94.5次6轮加密.     

基于RD域分块的改进距离徙动成像算法

研究了二维频域成像算法,提出一种基于RD域分块的改进距离徙动成像算法,并将该算法与近似算法和一般逆变标算法进行了点阵目标仿真和运算效率比较.当测绘带较宽且距离徙动较大时,该算法聚焦性能优于近似算法和一般逆变标算法.通过比较还可看出该算法运算效率高于逆变标算法.最后用实测数据仿真验证了该算法是可行的.