锦屏一级左岸垫座以下坝基地质缺陷初步评价

锦屏一级左岸垫座以下发育的不良地质单元,不仅破坏其岩体的完整性,而且可能导致建基面抗变形能力的不均匀性,以致对坝基岩体带来不良影响,危及拱坝安全。立足于坝基岩体质量环境,将垫座以下不良地质体划分为内倾顺层构造带,陡倾切层构造带,溶蚀裂隙带等三大综合缺陷类型,并阐述了各类缺陷的性状及其对坝基完整性、均匀性、变形性等方面的控制作用,分析了其典型声波曲线的波速量值及衰减特征。由此,按"轻度"、"中等"、"强烈"三个等级,定性的分区评价了各部位缺陷对坝基岩体的影响程度。着重认为f2断层附近,规模较大、间距较小、波速值低(2500-3500m ·s^-1)的内倾顺层构造带,不仅控制着岩体的抗剪性能,而且对坝基变形分异和基地应力分布存在"强烈"影响,应对其进行单独处理。     

Risk analysis with contractual default. Does covenant breach matter?

Mergers and acquisitions (M&A), private equity and leveraged buyouts, securitization and project finance are characterized by the presence of contractual clauses (covenants). These covenants trigger the technical default of the borrower even in the absence of insolvency. Therefore, borrowers may default on loans even when they have sufficient available cash to repay outstanding debt. This condition is not captured by the net present value (NPV) distribution obtained through a standard Monte Carlo simulation. In this paper, we present a methodology for including the consequences of covenant breach in a Monte Carlo simulation, extending traditional risk analysis in investment planning. We introduce a conceptual framework for modeling technical and material breaches from the standpoint of both lenders and shareholders. We apply this framework to a real case study concerning the project financing of a 64-million euro biomass power plant. The simulation is carried out on the actual model developed by the financial advisor of the project and made available to the authors. Results show that both technical and material breaches have a statistically significant impact on the net present value distribution, and this impact is more relevant when leverage and cost of debt increase.     

Nash equilibria in competitive project scheduling

We consider the problem of scheduling activities of a project by a firm that competes with another firm that has to perform the same project. The profit that a firm gets from each activity depends on whether the firm finishes the activity before or after its competitor. It is required to find a Nash equilibrium solution or show that no such solutions exist. We present a structural characterization of Nash equilibrium solutions, and a low order polynomial algorithm for the problem.     

On the latest starting times and criticality of activities in a network with imprecise durations

This paper deals with problems of computing possible values of latest starting times and determining types of criticality for all activities in a network with interval or fuzzy activity durations. Although the problem of computing the latest starting times has been solved, a novel polynomial algorithm which is easy to understand and improves complexity is proposed.     

基于面向对象程序设计语言的代码分类提取模型研究及应用

通过对多种面向对象开发工具开发软件进行文件组织分析,提出一个文件组织的层次模型.通过对具体VB语言的分析,获取VB语言的项目组织规则,并编程实现提取VB项目中的对象,包括属性和代码,以及对象之间的关系.     

估计迹长概率分布函数的新方法及其应用

本文提出一种估计迹长概率分布函数的新方法。该方法的优点是不需要有节理在测窗上出露长度的数据, 有效的减少了野外工作量。     

Optimizing the supply chain configuration for make-to-order manufacturing

We consider a make-to-order (MTO) manufacturer who has won multiple contracts with specified quantities to be delivered by certain due dates. Before production starts, the company must configure its supply chain and make sourcing decisions. It also needs to plan the starting time for each production task under limited availability of resources such as machines and workforce. We develop a model for simultaneously optimizing such sourcing and planning decisions while exploiting their tradeoffs. The resulting multi-mode resource-constrained project scheduling problem (MMRCPSP) with a nonlinear objective function is NP-complete. To efficiently solve it, a hybrid Benders decomposition (HBD) algorithm combining the strengths of both mathematical programming and constraint programming is developed. The HBD exploits the structure of the model formulation and decomposes it into a relaxed master problem handled by mixed-integer nonlinear programming (MINLP), and a scheduling feasibility sub-problem handled by constraint programming (CP). Cuts are iteratively generated by solving the feasibility sub-problem and added back to the relaxed master problem, until an optimal solution is found or infeasibility is proved. Computational experiments are conducted to examine performance of the model and algorithm. Insights about optimal configuration of MTO supply chains are drawn and discussed.     

Three-dimensional mathematical model and its application in the neighborhood of the Three Gorges Reservoir dam in the Yangtze River

The calculation of flow and sediment transport is one of the most important tasks in river engineering. The task is particularly difficult because a number of complex physical phenomena should be accounted for more realistically in a model with a predictive power. Three-dimensional calculations of river flow and suspended sediment transport are performed in this paper with application in the Three Gorges Reservoir in the Yangtze River. A period of 76 years after the dam is built is simulated and the results are compared with laboratory measurements obtained by Tsinghua University whereby the model is verified and calibrated. Generally speaking, the calculated results agree well with the experiments, demonstrating that the present model can be used for flow and sediment transport prediction in rivers. The project supported by the National Natural Science Foundation of China (50009004)     

Preference programming for robust portfolio modeling and project selection

In decision analysis, difficulties of obtaining complete information about model parameters make it advisable to seek robust solutions that perform reasonably well across the full range of feasible parameter values. In this paper, we develop the Robust Portfolio Modeling (RPM) methodology which extends Preference Programming methods into portfolio problems where a subset of project proposals are funded in view of multiple evaluation criteria. We also develop an algorithm for computing all non-dominated portfolios, subject to incomplete information about criterion weights and project-specific performance levels. Based on these portfolios, we propose a project-level index to convey (i) which projects are robust choices (in the sense that they would be recommended even if further information were to be obtained) and (ii) how continued activities in preference elicitation should be focused. The RPM methodology is illustrated with an application using real data on road pavement projects.     

Solid-liquid equilibrium and the hydrogen bond in crystals

The types of hydrogen-bonded associates formed in phenol and aromatic acid crystals are discussed. A hypothesis is advanced that dissolution of a self-associated solid substance in a nonpolar solvent consists in transferring the associates existing in the crystal phase into saturated solution. The mechanism has been confirmed for several aromatic acids and phenols.