Resource Search in Unstructured Peer-to-Peer System Based on Multiple-Tree Overlay Structure

We propose a multiple-tree overlay structure for resource discovery in unstructured P2P systems. Peers that have similar interests or hold similar type of resources will be grouped into a tree-like cluster. We exploit the heterogeneity of peers in each cluster by connecting peers with more capacities closer to the root of the tree. The capacity of a peer can be defined in different ways （e.g. higher network bandwidth, larger disk space, more data items of a certain type etc.） according to different needs of users or applications.     

关于模拟法描会聚点电场的讨论

本文论证了“ＱＥ－２”型静电场描迹中模拟聚焦电场的电极在设计上有误的观点。     

德国Lenze公司47系列直流调速控制器的研究

本文对德国Lenze公司47系列直流调速控制器进行了系统的分析研究，其触发电路较具特色，值得学习与借鉴。     

基于遗传算法的层合板结构的可靠性优化设计

采用遗传算法分析了存在初始缺陷的复合材料层合板的可靠性优化问题．优化设计时，以层合板结构的厚度最小为目标函数，以可靠度要求为约束条件．在可靠度分析中，取初始缺陷、强度参数、单元层的厚度为随机变量，采用一阶矩法和Tsai-Wu准则分析每个单元层的失效概率，系统失效概率的计算基于串联系统假定．通过比较遗传算法与序列二次规划法的计算结果，证实了遗传算法用于可靠性优化设计的有效性．     

Detection of the translational oscillations of the Earth''''s solid inner core based on the international superconducting gravimeter observations

Before about 100 years, the layered structures of the Earths body and the existence of the liquid core had been found, then the solid inner core and detailed structures in the interior of the Earth are demonstrated, it proves that the satisfied achievements had been obtained in recogni-tion of the Earths interior structures. In recent years, with the increasing requirements of the basic sciences and space techniques to geodynamics of the Earths interior, the theoretical study and practical de…     

《微机原理与应用》课程成绩的统计分析及对策

《微机原理与应用》是信息大类专业的一门极其重要的专业基础课,其知识点多,内容抽象,学生理解难度高,是诸多专业课中最难的课程之一。以大连海事大学信息类专业学生考试成绩为样本,对各个知识点的得分率进行深入统计分析。分析表明,目前的教学方法在课程教学最重要的硬件扩展应用部分以及汇编语言程序设计部分并不理想。针对教学中存在的问题,课程组在"十二五"国家级实验教学示范中心建设的支持下,提出了详尽的对策,包括更新实验教学器材、改革实验教学内容以及建立教学环节中的激励机制。实践表明,教学改革方案实施效果良好,学生学习效果有明显改善,掌握知识能力有较大幅度提高,课程考试成绩也有较大提升。     

有机半导体非平衡态HOMO和LUMO能量位移规律与OLED中“热激子”形成的唯象理解

以能斯特方程为基础, 通过分析电流密度与氧化还原物种活度变化, 即载流子浓度变化的关系, 计算出有机半导体材料电极电势的变化, 从而建立起有机半导体前线轨道, 即最高占据分子轨道(HOMO)能级和最低未被占据分子轨道(LUMO)能级相对于热力学平衡态的能量位移随电流密度变化的数学关系. 进而依据能级能量位移引起的能隙变化, 提出了有机电致发光显示器（OLED）中“热激子”的产生机制.     

Selective adsorption behaviors of guest molecules COR in the hexamer host networks at liquid/solid interface

Here,the selective adsorption behaviors of guest molecule COR in two hexamer host grids were investigated by means of scanning tunnelling microscope(STM).The assembled structures of small functional organic molecules TTBTA and TATBA were thermodynamically stable.Interestingly,the introduction of the guest molecule COR destroyed the original hexamer structure of TTBTA and combined with it to form a new triangular host-guest system.Different from TTBTA,the introduction of the guest molecule COR did not affect the six-membered ring structure of TATBA.Furthermore,the co-assembly structure of TTBTA/TATBA/COR was established and the guest molecule COR showed preferential adsorption to the TATBA host grid.Density functional theory(DFT) calculations had been performed to disclose the mechanism of the involved assemblies.     

Yb3+掺杂稀土钽铌酸盐的晶体场从头计算研究

Yb³⁺掺杂晶体材料是重要的激光材料,在超短脉冲激光、大功率激光等领域有重要应用前景,但长期以来很难通过实验拟合确定Yb3+晶体场参数,尤其是低对称体系,从头计算是解决此问题的重要途经.本文介绍了适合计算稀土离子掺杂晶体的从头计算DV-Xα方法和有效哈密顿量模型,用该方法计算了Yb³⁺掺杂M型和M'型钽铌酸盐的晶场参数和旋轨耦合参数,得到的能级结构和实验能很好地符合,并发现了Yb³⁺掺杂钽铌酸盐的晶场强度参数随稀土原子序数呈现规律变化.表明结合DV-Xα计算和有效哈密顿量方法是计算Yb³⁺掺杂低对称钽铌酸盐晶体场的有效途径,结果显示Yb3+掺杂钽铌酸盐晶体有望成为新型全固态激光工作物质.     

二维超声联合超声造影TIC参数在乳腺导管内病变良/恶性诊断中的应用价值

本研究分析了二维超声(2DUS)联合超声造影(CEUS)时间-强度曲线(TIC)参数在乳腺导管内病变良/恶性鉴别诊断中的应用价值.选取乳腺导管内病变患者81例(共93个病变),均行2DUS及CEUS检查.结果显示,2DUS检出恶性病变17个,良性病变48个,诊断准确度69.89％(65/93)、敏感度53.13％(17...