基于分形理论的河床表面形态量化方法研究

提出以河床表面分形维数从整体上量化河床形态,并依据表面积—尺度法原理,在对现有面分维计算方法的表面积估算、边界处理及无标度区判断等方面进行改进的基础上,给出了适用于具有不规则边界的表面分形维数计算方法,该方法对河床表面分维计算具有较好的适用性.将典型河段的年内冲淤变化、局部河势、河型与河床表面分形维数变化结合起来,说明了河床表面形态具有一定的分形特征,河床表面分形维数可随着河床的冲淤变化而改变,河床形态冲淤起伏愈剧烈,则河床表面分形维数愈大,其能定量反映河床形态的复杂程度,可用于河势量化分析、河型判别以及河道形态阻力计算等相关问题研究.     

试论无权处分

无权处分涉及权利人和第三人的利益关系,不同的法律规定直接关乎交易利益与安全。本文针对我国合同法第51条关于无权处分合同的有效性的规定,主要通过保护当事人利益和鼓励交易的原则,探讨无权处分行为的性质和效力。     

DFT study on nonlinear optical properties of lithium-doped corannulene

The effects of lithium doping on the nonlinear optical properties of new electrodes (lithium-doped corannulene) were investigated in detail. Nine dynamically stable geometries of Lin-C20H10 (n=1, 2) are predicted by B3LYP/6-31G(d,p). Among these nine structures, the largest first static hyperpolarizability (β0) is computed to be 15314 au, which is dramatically larger than the β0 value of 74 au for C20H10, indicating that Li doping plays an important role in elevating the first hyperpolarizability of corannulene.     

公共图书馆延伸服务存在的问题及其完善

分析了公共图书馆开展延伸服务的意义,探讨了目前公共图书馆延伸服务存在的问题,针对公共图书馆延伸服务的完善提出了几点意见。     

Abrasive wear behavior of cast iron coatings plasma-sprayed at different mild steel substrate temperatures

Three kinds of cast iron coatings were prepared by atmospheric plasma spraying. During the spraying, the mild steel substrate temperature was controlled to be averagely 50, 180, and 240℃, respectively. Abrasive wear tests were conducted on the coatings under a dry friction condition. It is found that the abrasive wear resistance is enhanced with the substrate temperature increasing. SEM observations show that the wear losses of the coatings during the wear tests mainly result from the spalling of the splats. Furthermore, the improved wear resistance of the coatings mainly owes to the formation of oxides and the enhancement in the mechanical properties with the substrate temperature increasing.     

后发国家自主创新中的政府作为——试述韩国、芬兰的成功实践对中国的启示

在激烈的国际竞争中,自主创新能力薄弱日益成为制约我国经济发展的瓶颈。而创新的成功离不开政府的科学计划和有效组织。值得中国借鉴和学习的后发国家政府作为的国际经验已经很丰富,其中韩国和芬兰重视政府作为的做法对我们打造创新型国家具有参考价值。     

多孔介质模型的三维重构方法

建立准确的多孔介质模型在微观渗流机理的研究中具有重要意义.为了更加方便准确地建立多孔介质模型,总结了多孔介质模型重构的物理实验方法和数值重构方法,通过重构方法的优缺点对比及适用性分析,优选出马尔可夫链-蒙特卡洛方法(MCMC).针对3种不同性质的多孔介质,采用MCMC方法分别对其进行了重构.结果表明,MCMC方法计算速度快,适用范围广泛,重构效果好.最后将MCMC方法扩展到三维空间,重构出三维多孔介质模型,为微观渗流机理的研究提供了一个模拟平台.     

浅析弘扬雷锋精神对高校精神文明建设的推动作用

雷锋精神是中华民族的宝贵精神财富和重要精神力量。在高校精神文明建设中弘扬雷锋精神有助于激发高校师生思想道德建设热情,激扬人们心中蕴藏的美好思想品德,有助于凝聚高校师生的理想信念、价值追求,弘扬伟大的民族精神和时代精神,有助于凝聚高校师生的思想和意志,加快校园文化建设进程。     

关于高校思想政治理论课学生听课问题的几点认识

学生听课质量是影响教学效果的重要因素,要重视研究学生听课问题。影响学生听课质量的主要原因是学生主观偏见的思维定势、功利主义的心理状态、知识结构和能力的欠缺、缺乏锻炼的听课习惯等因素。提出了提高学生听课质量的建设性意见。     

Soundness analysis of compositional model of time-based petri nets

Workflow management systems are widely used in improving the efficiency of business processes.To develop a workflow management system is the key to workflow modeling.In this paper,the compositional time net is presented to model workflow processes on the basis of the analyzing methods of time Petri nets and workflows,and to describe the static relationships and the dynamic semantics of the task of multiple workflow composition.The paper puts more emphasis on checking the soundness of composed workflow,at the same time,combinational problems of non-conditional structure of the compositional time net are introduced and analyzed.A sufficient and necessary condition for determining the soundness of compositional nets is obtained.