基于随机活动工期的资源约束项目鲁棒性调度优化

项目进度计划的鲁棒性对于不确定条件下项目的顺利实施具有重要影响. 作者研究具有随机活动工期的资源约束项目鲁棒性调度问题, 目标是在可更新资源和项目工期约束下安排活动的开始时间, 以实现项目进度计划鲁棒性的最大化. 首先对所研究问题进行界定并用一个示例对其进行说明. 随后构建问题的优化模型, 设计禁忌搜索、多重迭代和随机生成三种启发式算法. 最后在随机生成的标准算例集合上对算法进行测试, 分析项目活动数、 项目工期和资源强度等参数对算法绩效的影响, 并用一个算例对研究进行说明, 得到如下结论: 禁忌搜索的满意解质量明显高于其他两种算法; 当资源强度或项目工期增大时, 平均目标函数值上升, 禁忌搜索的求解优势增强. 研究结果可为不确定条件下项目进度计划的制定提供决策支持.     

国内外钢材市场价格发现功能研究

钢材产业是我国的支柱产业.与国外钢材市场不同, 国内出现了三类市场形态: 电子交易市场、期货市场、现货市场.钢材电子交易市场是我国独有的一种钢材交易市场.该市场的价格发现功能一直被理论界和 实业界所关注.研究国内外钢材交易市场的价格发现功能对于引导国内各钢材市场的健康发展和形成钢材定价中心尤为重要. 本文运用共同因子度量模型的两种经典方法, 测算并分析了国内三类钢材交易市场和国外两大钢材期货市场的价格发现.结果表明: 电子交易市场的价格发现功能明显优于期货、现货市场; 与伦敦金属交易所和印度国家商品及衍生品交易所相比, 国内钢材电子交易市场的价格发现功能更强; 且国内外钢材期货价格尚不能真实反映价格变化趋势.     

CNFs掺杂浓度对CNFs／LDPE复合材料空间电荷的影响

为改善低密度聚乙烯的电学性能,文中将镀镍后的碳纤维添加混入低密度聚乙烯中,通过熔融共混技术,制成CNFs／LDPE半导电层＋绝缘层双层样片．采用电声脉冲法（PEA）测量其空间电荷分布．实验结果表明：随着直流电场的增加,在CNFs／LDPE半导电层＋纯绝缘层双层样片中,当CNFs质量分数低于1％时,CNFs／LDPE半导电层对电场的削弱作用相对较小,样品中残余了相对较多的空间电荷．当CNFs质量分数超过1％时,CNFs／LDPE半导电层的导电机制发生了改变,注入的空间电荷量很少且短路后几乎无残余．尤其是CNFs质量分数为5％时,样品内除阴极附近有微量电荷外,样品内部几乎无空间电荷分布．     

Influence of the Tibetan Plateau uplift on the Asian monsoon-arid environment evolution

As one of the most important geological events in Cenozoic era,the uplift of the Tibetan Plateau(TP)has had profound influences on the Asian and global climate and environment evolution.During the past four decades,many scholars from China and abroad have studied climatic and environmental effects of the TP uplift by using a variety of geological records and paleoclimate numerical simulations.The existing research results enrich our understanding of the mechanisms of Asian monsoon changes and interior aridification,but so far there are still a lot of issues that need to be thought deeply and investigated further.This paper attempts to review the research on the influence of the TP uplift on the Asian monsoon-arid environment,summarize three types of numerical simulations including bulk-plateau uplift,phased uplift and sub-regional uplift,and especially to analyze regional differences in responses of climate and environment to different forms of tectonic uplifts.From previous modeling results,the land-sea distribution and the Himalayan uplift may have a large effect in the establishment and development of the South Asian monsoon.However,the formation and evolution of the monsoon in northern East Asia,the intensified dryness north of the TP and enhanced Asian dust cycle may be more closely related to the uplift of the main body,especially the northern part of the TP.In this review,we also discuss relative roles of the TP uplift and other impact factors,origins of the South Asian monsoon and East Asian monsoon,feedback effects and nonlinear responses of climatic and environmental changes to the plateau uplift.Finally,we make comparisons between numerical simulations and geological records,discuss their uncertainties,and highlight some problems worthy of further studying.     

供应链的系统运作模式分析与建模——基于复杂自适应系统范式的研究

整体运作环境的变化使得传统的方法已经无法合理解决当今供应链管理中出现的复杂问题。应用复杂性科学的理论,本文以复杂自适应系统（Complexity Adaptive System, CAS）范式作为分析方法,系统性诠释了供应链的整体运作模式。文中首先以“适应性造就复杂性”的思想为指导,认为供应链是一个（CAS）,并建立了相应的概念模型,然后基于此模型,探讨了供应链管理的策略性原则。文章最后在桑塔费研究所开发的智能仿真平台-SWARM的基础上,建立了一个基于Multi-Agent的供应链仿真模型。研究表明该范式能够更好的分析与描述供应链这一复杂系统发生、创新、学习和适应等行为的本质。     

Thermal expansion in lead zirconate titanate

The volume anomalies with temperature variations in tin-modified lead zirconate titanate ceramics are investigated. Experimental results show that the volume changes are related to the phase transitions induced with temperature. The magnitude and orientation of crystal volume changes are dependent on the particular phase transition. When antiferroelectrics is transformed to ferroelectrics or paraelectrics the volume expands. Oppositely when ferroelectrics is transformed to antiferroelectrics or paraelectrics the volume contracts. In the transition of antiferroelectric orthorhombic structure to tetragonal structure or ferroelectric low-temperature rhombohedral structure to high-temperature rhombohedral structure, there are also revealed apparent anomalies in the curves of thermal expansion. Among them, the volume strain caused by the transition between antiferroelectrics and ferroelectrics is the biggest in magnitude, and the linear expansion dL/L₀ and the expansion coefficient (dL/L ₀)/dT can reach 2.8 × 10⁻³ and 7.5 × 10⁻⁴ K⁻¹ respectively.     

政企联合储备模式下应急物资储备及采购定价研究

为提高灾害发生后应急物资的供给能力，降低政府单独储备应急物资时承担的风险及成本，文章设计了一个基于政府主导的政企联合储备应急物资模型，并对合作中的两个关键问题——物资储备量及采购定价进行了研究.在考虑政企双方同时参与现货市场的情形下，文章通过逆序推导法给出了企业最优储备量决策及政府最优采购定价，并与政府单独储备模式进行了对比分析，发现联合储备模式能够有效降低政府采购成本，提高企业收益，实现双方合作共赢.此外，文章还进一步分析了灾害事件发生概率，政府自身储备量等因素对政企双方决策，各自成本收益及增减变化的影响，发现随着灾害事件发生概率和现货市场采购价格的增加，联合储备模式的优越性越发明显，而过多的政府自身储备量及企业参与现货市场的行为则会阻碍企业参与合作的积极性，削弱联合储备的优越性.文章的研究为政府联合企业开展应急物资储备工作提供了操作策略和指导法则.     

X70管线钢韧-脆断裂转变研究

在不同温度下研究了X70管线钢动态断裂韧度K1d,J1d和止裂韧度K1a以及夏氏V型缺口冲击韧度(CVN)。研究表明,断裂韧度受温度和加载速率的影响较为强烈;当温度由213K向193K逐渐降低而加载速率逐渐从0.01向1000mm/s增大时,断裂韧度逐渐减小;在恒温下,增大加载速率可以诱发韧-脆断裂转变,应引起足够重视。     

A novel fabrication of meso-porous silica film by sol-gol of TEOS

A homogeneous crack-free nano- or meso-porous silica films on silicon was fabricated by colloidal silica sol derived by hydrolyzing tetraethyl orthosilicate (TEOS) catalyzing with (C4H9)4N+OH- in water medium. The solution with ratio of H2O/TEOS> or =15, R4N+ and glycerol as templates, combining with the hydrolyzed intermediate, controlled the silica aggregating; the templated silica film with heterostructure was developed into homogeneous nano-porous then meso-porous silica films after being annealed from 750 degrees C to 850 degrees C; the formation mechanism of the porous silica films was discussed; morphologies of the silica films were characterized. The refractive indexes of the porous silica films were 1.256-1.458, the thermal conductivity < 0.7 W/m/K. The fabricating procedure and the sequence had not been reported before.     

Web-Based Information Systems and Applications： A Survey

World Wide Web (WWW) has given rise to phenomenal growth in Web information systems and applications. And the Internet transcends national and geographical boundaries and has brought about unprecedented opportunities for software deployment to satisfy the application needs of all walks of life. Since the Web provides cross-platform universal access to resources for the massive user population, even greater demand is proposed to manage data and information effectively.