A method for the efficient prioritization of infrastructure renewal projects

The infrastructure renewal program at MIT consists of a large number of projects with an estimated budget that could approach $1 billion. Infrastructure renewal at the Massachusetts Institute of Technology (MIT) is the process of evaluating and investing in the maintenance of facility systems and basic structure to preserve existing campus buildings. The selection and prioritization of projects must be addressed with a systematic method for the optimal allocation of funds and other resources. This paper presents a case study of a prioritization method utilizing multi-attribute utility theory. This method was developed at MIT's Department of Nuclear Engineering and was deployed by the Department of Facilities after appropriate modifications were implemented to address the idiosyncrasies of infrastructure renewal projects and the competing criteria and constraints that influence the judgment of the decision-makers. Such criteria include minimization of risk, optimization of economic impact, and coordination with academic policies, programs, and operations of the Institute. A brief overview of the method is presented, as well as the results of its application to the prioritization of infrastructure renewal projects. Results of workshops held at MIT with the participation of stakeholders demonstrate the feasibility of the prioritization method and the usefulness of this approach.     

Continued fraction for formal laurent series and the lattice structure of sequences

Besides equidistribution properties and statistical independence the lattice profile, a generalized version of Marsaglia's lattice test, provides another quality measure for pseudorandom sequences over a (finite) field. It turned out that the lattice profile is closely related with the linear complexity profile. In this article we give a survey of several features of the linear complexity profile and the lattice profile, and we utilize relationships to completely describe the lattice profile of a sequence over a finite field in terms of the continued fraction expansion of its generating function. Finally we describe and construct sequences with a certain lattice profile, and introduce a further complexity measure.     

Coding distributive lattices with Edge Firing Games

In this note, we show that any distributive lattice is isomorphic to the set of reachable configurations of an Edge Firing Game. Together with the result of James Propp, saying that the set of reachable configurations of any Edge Firing Game is always a distributive lattice, this shows that the two concepts are equivalent.     

非线性动态系统“黑箱”建模方法的研究

本文研究弱非线性动态系统“黑箱”建模的理论和方法，并简要给出根据此方法建模的结果。     

基于格子Boltzmann方法的换热器优化模拟

为优化换热器的结构设计,用格子Boltzmann方法(Lattice Boltzmann Method,LBM)结合多孔介质模型模拟换热器内的换热,研究雷诺数、普朗特数和热扩散率比的变化对温度场和换热性能的影响.模拟结果表明:在小雷诺数范围内,随着雷诺数的增加,努塞尔数先增加后减小,即存在一个使换热性能达到最好的雷诺数;随着普朗特数的增加,努塞尔数减小,换热性能降低;随着热扩散率比的增加,换热性能提高.分析不同管柱排列方式对换热性能的影响,结果表明:叉排的换热效果明显优于顺排,当横向节距等于2时,对于均匀顺排或叉排,努塞尔数均随纵向节距的增加而减小,这与实验结果相符;对于非均匀叉排,采用"前密"或"中间密"的排布方式有利于换热.     

基于模糊AHP的大学课堂教学质量评价研究

为了对大学教师课堂教学质量进行有效的监督和管理,建立了现代信息技术环境下大学教师课堂教学质量评价指标体系,基于模糊综合评判法和层次分析法(AHP)建立了教师课堂教学质量评价模型,应用此模型实例分析某教师的课堂教学质量并提出相应的提升策略,提高了评价的科学性和实用性。     

基于AHP的樱园农家乐SWOT分析及发展对策

利用AHP和SWOT分析理论,提出了西安樱园观光旅游农家乐的发展策略.根据实地调研,探讨了樱园农家乐发展所面临的优势、劣势、机遇和威胁,建立了总体层次分析评价指标体系,确定了各层次的指标权重,分析了四种备选的优化方案.最后建议,樱园农家乐的发展应充分发挥“体验参与模式”的优势,把握政府引导和政策支持的机遇.     

基于极限学习机的堤防工程多元风险指标评价方法

为提高堤防工程风险评价的准确性,提出了基于极限学习机的堤防工程多元风险指标评价方法。首先,综合考虑影响堤防风险的28个评价指标,利用层次分析法从预警系统、堤防工程系统、环境系统和社会经济系统这4个方面建立了堤防工程多元风险评价指标体系。接着,基于极限学习机算法对28个指标进行标准化处理及分级标准构建,以风险指标作为输入量,分级隶属度作为输出量,划分风险等级,量化评价指标,估计多元风险评价指标值和判断风险的严重程度。最后,依托鄱阳湖重点堤防——康山大堤,构建多元风险评价指标体系,运用极限学习机算法计算多元风险评价指标值。评价结果表明:康山大堤目前处于基本安全水平,符合康山大堤经过两次加固后的工程实际情况,并与其他方法进行对比,验证了提出方法的可靠性和有效性。该方法可拓展应用到其他重要水工结构工程风险评估中。     

基于级差最大化组合赋权法的地下水功能评价

针对地下水功能评价中单独采用主观赋权法或客观赋权法存在的问题,结合二者的优点,采用基于主观赋权的层次分析法与客观赋权的熵权法相结合的级差最大化组合赋权法评价地下水功能,并通过计算不同赋权方法权重结果与平均值的相对偏差来衡量级差最大化组合赋权法的准确性。将该方法应用于伊犁河谷西北部平原区浅层地下水功能评价,评价结果基本符合评价区实际情况,验证了该评价方法在地下水功能评价中的可行性。