一种铁路客运专线用防水涂料的研制

介绍了铁路客运专线桥梁用防水涂料的研制意义,用正交试验确定了该种新型涂料所用到的重要原料的种类及用量,研究了树脂与引发剂对固化速度的影响,树脂与单体的添加质量对涂膜断裂伸长率及位伸强度的影响,以及颜填料添加质量对涂膜性能的影响,并从施工的角度考察了温湿度对涂膜干燥性的影响。     

限定领域的自动问答系统研究

目前,自然语言处理系统由于缺乏语义信息及知识理解和推理能力,因此存在很多缺陷,在自动问答领域中很难分清用户表达的真正意图,并给出用户满意的答案.本文就此给出基于句法语义的问句分析方法,采用本体构建技术构建答案库,在此基础上进行领域知识语义推理,实现智能问答.本研究以黄山旅游为限定领域建立问答系统,试验结果表明多策略的方法是有效的.     

网格任务调度模型的研究

网格任务调度是采用适当的调度策略把应用程序分配到异构的计算节点上进行高效的执行并返回正确结果的过程。本文研究了经典网格任务调度模型,分析了各自的优缺点,并提出了一种包含有树形全局调度模型和局部调度模型的两层结构模型,此树形全局调度模型通过负载从根节点自上而下的迁移,能够很好地实现网格系统的负载平衡。通过二叉树的节点删除算法能够很好地解决模型中节点的失效问题,因此具有很好的安全性和可靠性。     

试谈铁路运输企业发展第三方物流的对策

从物流及第三方物流的概念着手,主要分析了物流与铁路运输的本质区别,并就铁路运输开展第三方物流优势及存在问题进行了详细分析,重点论述了铁路运输业开展第三方物流的可行性及有关对策。     

Electrical resistance behavior of vinylester composites filled with glass-carbon hybrid fibers

Vinylester (bismethacryloxy derivative of a bisphenol-A type EP resin, VE) composites with glass-carbon hybrid fibers (CF-GF) weight fraction of 50%, were prepared by the compress molding method. The distribution of carbon fiber in the hybrids was observed by stereomicroscope. The electrical resistance behavior of the composites filled with different carbon fiber (CF) weight contents (0.5% to 20%) was studied. The experimental results show that the electrical resistance behaviors of CF-GF/VE composites are different with those of CF/VE composites because carbon fibers’ conducting networks are broken by the glass fibers in the CF-GF/VE composites. The carbon fibers distribute uniformly in the networks of glass fibers (GF) like single silk and form the semi-continuous conducting networks. Composite filled with GF-CF hybrid has a higher percolation threshold than that filled with pure CF. At that time, the resistivity of CF-GF/VE composites varies little with the temperature increasing. The temperature coefficient of resistivity in GF-CF/VE composite is less than 317 ppm and the variation of the resistivity after ten thermal cycles from 20 °C to 240 °C is less than 1.96%. Funded by the Natural Science Foundation of Hubei Province (No. 2007ABA028)     

Fabrication and characterization of nano silver powder prepared by spray pyrolysis

Silver powder was fabricated by spray pyrolysis, using 2%–20% AgNO₃ solution, 336–500 mL/h flux of AgNO₃ solution, 0.28–0.32 MPa flux of carrier gas and in the 620–820 °C temperature range. The effects of furnace set temperature, concentration of AgNO₃ aqueous solution, flux of AgNO₃ aqueous solution as well as carrier gas on the morphology and particle size distribution of silver powder, were investigated. The experimental results showed that with the high concentration of AgNO₃ aqueous solution, the average grain size of silver decreased with the increasing of furnace set temperature. But the gain size distribution was not homogenous, the discontinuous grain growth occurred. With the low concentration of AgNO₃ aqueous solution, the higher furnace set temperature made the nano sliver grains sintered together to grow. Nano silver powder about 100 nm was fabricated by spray pyrolysis, using 2wt% AgNO₃ solutions, 336 mL/h flux of AgNO₃ aqueous solution, 0.32 MPa flux of carrier gas at 720 °C furnace set temperature.     

一种基于非光滑信赖域理论的经济学均衡问题新算法

针对一般经济均衡问题模型,将其转换为非线性互补问题模型,提出了应用非光滑信赖域算法对其进行求解的新方法.在适当的条件下,证明了此算法是全局收敛的,并通过数值试验表明该算法是可行有效的.     

带参数信息素的蚁群算法

针对蚁群算法搜索时间长、容易陷入局部最优以及参数选择难的缺点,提出了带参数信息素的蚁群算法.该算法使用新的信息素更新机制,使得蚂蚁具有更强的全局搜索能力;同时,算法引入参数信息索,使得蚂蚁能够按概率选择较合适的参数组合,在一定程度上解决了参数选择的困难.对旅行商问题的仿真结果表明,该算法是可行有效的.     

一类Toeplitz矩阵的平方根

给出了一类上三角Toeplitz矩阵的平方根的新的性质定理,还给出了求其平方根的迭代公式,数值例子验证了迭代公式的正确性.     

Bifurcation analysis for an SMIB power system with series capacitor compensation associated with sub-synchronous resonance

In this paper,an introduction to the bifurcation theory and its applicability to the study of sub-synchronous resonance (SSR) phenomenon in power system are presented. The continuation and bifurcation analysis software AUTO97 is adopted to investigate SSR for a single-machine-infinite-bus power system with series capacitor compensation. The investigation results show that SSR is the result of unstable limit cycle after bifurcation. When the system exhibits SSR, some complex periodical orbit bifurcations, such as torus bifurcation and periodical fold bifurcation, may happen with the variation of limit cycle. Furthermore, the initial operation condition may greatly influence the ultimate state of the system. The time-domain simulation is carried out to verify the effectiveness of the results obtained from the bifurcation analysis.