复杂网络的节点重要性综合评价

复杂网络中的节点重要性研究在不同领域都具有重要意义。针对单一指标评价的局限性和片面性以及现有的一些综合评价方法不够准确等问题,提出了一种新的综合评价方法,该方法结合改进的主成分分析法和TOPSIS法计算节点重要性的排序结果。通过对ARPA网络和美国航空网络进行实验分析,验证了该方法的准确性和有效性,它为进一步完善节点重要性评价方法奠定了基础。     

基于属性约简集评价节点重要性研究

社会网络成员的重要性确定通常依赖结构属性对网络节点的评价。首先定义了网络中节点排序可区分以及属性约简集的概念，并在此基础上量化了属性聚类的阈值，从而确定了类别的数量。设计了网络节点重要性的属性约简集评价算法。通过与度、介数、全属性评价在人工网络、海豚网上的实现，证明了属性约简集评价节点排序的可行性。通过属性约简集在海豚网、9·11恐怖分子合作网上的节点评价值、网络鲁棒性以及节点可区分性等方面的应用对比分析，发现属性约简集评价节点重要性既兼顾了网络结构的完整性，又避免了单一属性评价的片面性和多个属性之间的属性冗余性，提高了节点评价结果的准确性，降低了算法复杂度。     

基于遥感与生态服务模型的青岛市生态保护重要性评价

生态保护重要性评价是“双评价”的重要组成部分,是合理规划国土空间的重要依据。提出一种将遥感数据作为主要驱动数据,采用生态服务模型与生态敏感性指数相结合的生态保护重要性评价方法,定量评价了2018年青岛市陆域的生态保护等级。依据“双评价”标准,综合考虑区域内重要生态服务功能区、生态脆弱区和生态保护因子,划定青岛市生态保护重要性,并根据生态保护红线对评价结果进行验证和分析。结果表明：基于遥感与生态服务模型的生态保护重要性评价方法能够较好地评价区域生态保护重要性,青岛市生态保护重点区面积为1 125.57 km²,约占全市陆域面积的10.34 %,主要分布在青岛市东部的崂山片区、西南部的胶南山区以及北部的大泽山片区等生态系统服务功能较为丰富且生态敏感性较高的部分地区。研究提出的生态保护重要性评价方法为“双评价”工作的开展提供了良好的技术支撑,评价结果对于科学合理地编制城市发展规划和建设生态文明城市具有重要的参考价值。     

绿色评价模型的互模拟等价及逻辑保持

绿色计算中,复杂系统的绿色评价是一个重要的研究课题,其核心任务是判断运行时时间、空间资源消耗是否满足环境约束或限定.设计时,采用模型检测技术,自动、完备、高效地进行绿色评价,是一种新颖且有效的解决方案,但可能出现的状态爆炸问题将影响评价成败或效率.引入随机决策过程作为绿色评价模型;用时态逻辑刻画包含行为正确性及时间、空间资源约束的绿色评价指标;定义不确定语义理解下评价模型状态的互模拟等价规则,给出互模拟商的构造方法以及商模型调度,并比较等价语义下的行为机理;运用结构化归纳法证明互模拟等价保持评价结论.分析表明,互模拟等价可用作状态约简手段,为基于模型的绿色评价提供理论支撑和技术手段.     

LPG储罐事故危险特性动态模拟评价方法及软件开发

对LPG危险特性、易发事故及其发生机理进行全面系统地分析、归纳和分类,按LPG储罐事故可能发生的先后顺序．将其事故类型分为六类,建立了一套可描述事故特征参数随时间和距离的变化过程的LPG储罐事故危险特性动态模拟评价系统方法。为便于推广和实际应用,根据水平喷射火的特殊形状,提出了其人员伤亡人数和直接财产损失计算方法;将改进的喷射流扩展半径表达式用于喷射火模拟评价,将修正的TNO爆炸特征曲线拟和关系式和蒸气云爆炸人员伤亡距离关系式等改进方法应用于蒸气云爆炸模拟评价。结合Visual C 编程语言与MATLAB仿真技术,实现了事故后果动态模拟的软件化、可视化。本方法对有效预测、预防、控制LPG危险源事故具有重要工程应用价值和指导意义。     

管理模拟教学法的应用及评价——以人力资源管理课程为例

从我国目前高等院校人力资源管理课程教学中可以发现,创新教学方法的要求还没有在教学实施中真正体现,传统的课堂单项灌输和学生“被动学习”的现状     

Damage analysis and numerical simulation for failure process of a reinforced concrete arch structure

This work focuses on the implementation of damage mechanics model to explain and understand failure mechanisms of the concrete structures. A tensorial damage theory and an isotropic application to the arch ribs of a real bridge are presented. Two reinforced concrete arch ribs of a 28 year old bridge has been removed from the field to the laboratory. They were loaded up to failure in order to study the remaining strength of the structure. The damage model involves three independent parameters for simulating the damage behaviors of the concrete material. The damage theory—additional load—finite element method is developed to simulate numerically the failure process of the RC structures based on the proposed damage model. The predicted displacements, strains and failure mode of the RC arch are good agreement with the experimental results. The values of the three material parameters that describe the damage characteristics of concrete were obtained. The numerical calculations revealed the interested behaviors of concrete in a damaging process. The proposed damage model can be used effectively to describe the damage and fracture behaviors of concrete.     

An iterative procedure for collapse analysis of reinforced concrete plates

An iterative procedure is proposed for evaluating the ultimate load of a laterally loaded plate discretized by finite elements. The procedure regards reinforced concrete plates, but it can be extended to metallic plates without any conceptual change. The stress and displacement fields are approximated by means of a finite element model with constant stress and linear displacement fields. Consequently, any load distribution is represented by the equivalent system of nodal forces for a given mesh. In the set of mechanisms compatible with the assumed discretization the best upper bound to the collapse multiplier of the actual load is obtained via linear programming. By dualization a sequence of linear programming problems is obtained which allows an evaluation of a lower bound of the collapse multiplier for the equivalent load system. When the mesh gets finer and finer, the value obtained does not change substantially anymore. This value can be regarded as an estimate of the collapse multiplier for the original load system. Some numerical examples of plates subjected to uniform pressure confirm the reliability of this approximate multiplier.     

Dynamic response simulation for reinforced concrete slabs

Present investigation comprises development of a new finite element numerical formulation for nonlinear transient dynamic analysis of reinforced concrete slab structures. Depending on many experimental data, new material constitutive relationships for concrete material have been formulated. A regression analysis of available experimental data in the SPSS-statistical program has been employed for formulating the proposed material finite element models, and the appropriateness of the models are confirmed through the histograms and measured indices of determination. Concrete slab structures were analyzed using eight-node serendipity degenerated plate elements. The constitutive models of the nonlinear materials are introduced to take into account the nonlinear stress–strain relationships of concrete. For studying the stress profile of the concrete slab through its thickness, a layered approach is adopted. Elastic perfectly plastic and strain hardening plasticity approaches have been employed to model the compressive behavior of concrete. Assumptions for strain rate effect were included in dynamic analysis by supposing the dynamic yield function as a function of the strain rate, in addition to be the total plastic strain. The yield condition is formulated in terms of the first two stress invariants. Geometrical nonlinearity was considered in analysis as a mathematical model based on the total lagrangian approach taking into account Von Karman assumptions. Implicit Newmark with corrector–predictor algorithm was used for time integration solution of the equation of the motion for slab structures. An incremental and iterative procedure is adopted to trace the entire response of the structure; a displacement convergence criterion is adopted in the present study. A computer program coded in FORTRAN has been developed and used for the dynamic analysis of reinforced concrete slabs. The numerical results show good agreement with other published studies’ results which include deflections.     

钢筋混凝土拱肋劲性骨架爬模施工分析

以国内某主跨300 m的外倾式非对称系杆拱桥为例,采用三维有限元法分析靠拱脚段钢筋混凝土拱肋爬模施工过程中劲性骨架的受力状态. 为简化计算,从结构安全和满足桥梁施工要求出发,合理假定模板系统及劲性骨架的载荷分担率,将劲性骨架简化为空间杆系、载荷简化为节点载荷. 该方法计算模型简单、结果偏于安全,可用于类似结构的工程近似计算.     

Evaluation of cracking potential for concrete arch dam based on simulation feedback analysis

It is still very difficult for researchers and engineers to implement the simulation analysis including a complete process and a full model with the complicated arch dam and the foundation, and to evaluate the cracking potential in the construction and service periods. To take Xiaowan project of China for an example, a practical system of simulation feedback analysis, a specific cracking criterion, and a resolution for the conflicting requirements of temperature and stress/strain simulation are presented, w...     

基于AM1量子化学方法的醇胺类缓蚀剂在模拟混凝土孔溶液中对钢筋缓蚀作用研究

用电化学极化曲线的方法评价了几种醇胺化合物在混凝土模拟孔溶液中对钢筋的缓蚀效果,用Gaussian03程序中的AM1方法计算了这几种醇胺化合物的量子化学参数,并采用最小二乘法,分别将它们的前线分子轨道能级、氮氧原子上的净电荷、分子偶极距以及热力学参数与相对缓蚀效率进行拟合.用所拟合的方程预测了这些醇胺的缓蚀效率,预测结果与实验结果基本相符.     

Numerical study of confinement effectiveness in solid and hollow reinforced concrete bridge piers: Methodology

A consistent methodology is suggested for modelling confinement in both solid and hollow reinforced concrete bridge pier sections, within the computational framework of three-dimensional nonlinear finite element analysis. The ultimate goal is to suggest the most convenient transverse reinforcement arrangements in terms of enhanced strength and ductility, as well as ease of construction and cost-effectiveness. The present study is particularly relevant with respect to confinement of hollow sections, for which previous experimental and analytical research is limited. Constitutive laws, modelling techniques, post-processing issues and preliminary applications are first introduced, and a large parametric model setup for circular and rectangular bridge piers of solid and hollow section, is subsequently presented. A detailed discussion follows on various issues concerning confinement modelling, aiming to broaden the scope and applicability of the suggested methodology. The respective numerical results and their interpretation and evaluation will be presented in a companion paper.     

Thin crack observation in a reinforced concrete bridge pier test using image processing and analysis

In reinforced concrete (RC) structural experiments, the development of concrete surface cracks is an important factor of concern to experts. One conventional crack observation method is to suspend a test at a few selected testing steps and send inspectors to mark pen strokes on visible cracks, but this method is dangerous and labor intensive. Many image analysis methods have been proposed to detect and measure the dark shadow lines of cracks, reducing the need for manual pen marking. However, these methods are not applicable for thin cracks, which do not present clear dark lines in images.This paper presents an image analysis method to capture thin cracks and minimize the requirement for pen marking in reinforced concrete structural tests. The paper presents the mathematical models, procedures, and limitations of our image analysis method, as well as the analysis flowchart, the adopted image processing and analysis methods, and the software implementation. Finally, the results of applying the proposed method in full-scale reinforced concrete bridge experiments are presented to demonstrate its performance. Results demonstrate that this method can capture concrete surface cracks even before dark crack lines visible to the naked eye appear.     

Numerical simulation of shrinkage and creep in patch-repaired axially loaded reinforced concrete short columns

This paper presents numerical results obtained from finite element simulations of the time-dependent behaviour of moderately loaded patch-repaired reinforced concrete short columns. Patch repair is a structural concrete repair method in which damaged concrete is replaced with one of a wide range of materials. Relative to the concrete substrate, the patch repair materials used in this study had different properties, such as the elastic modulus, shrinkage and creep. A priori, it would appear that simple theory such as the engineer's theory of bending cannot be used to quantify the behaviour of the patch-repaired member. Experimental evidence needed to clarify such issues remains scarce. The finite element simulations performed in this study indicate that shrinkage and creep cause the progressive shedding of the load carried by the patch repair to the concrete substrate. Finite element results compare favourably with the predictions of the engineer's bending theory. Relative to test results some qualitative agreement is observed though there is significant quantitative deviation.     

Numerical study of confinement effectiveness in solid and hollow reinforced concrete bridge piers: Analysis results and discussion

This paper presents the outcome of a large parametric numerical analysis of solid and hollow reinforced concrete piers taken from actually constructed bridges, based on a consistent three-dimensional nonlinear finite element methodology that was presented in a companion paper. Various transverse reinforcement arrangements and spacings were examined, as well as the effect of high-strength concrete on confinement effectiveness. The interpretation of numerical results mainly focuses on identifying the most convenient confinement configurations in terms of enhanced strength and ductility, as well as ease of construction and cost effectiveness. Furthermore, issues regarding confinement arrangements (often used in practice) that result in reduced section ductility are investigated and possible remedies are suggested. Finally, the broad applicability of the proposed methodology is established by application to a particularly complex (in terms of geometry and reinforcement detailing) hollow pylon section.