地震灾害农居易损性新方法研究

如何从定性到定量评价研究建筑结构抗震能力,尤其是量大面广的农村民居的抗震能力是一个重要而又棘手的问题。该文对12组墙片进行拟静力试验,得到了墙片的滞回曲线、骨架曲线和破坏状态,墙片的骨架曲线和破坏状态进行对比,按照对应的剪应力和位移角进行破坏等级划分,得到了农居主要承重构件墙片的破坏等级双参数定量划分方法。对五大类农居进行了6度~10度的震害矩阵完善,在农居震害矩阵的基础上提出了易损性指数计算新方法,解决了震害矩阵之间的评价问题。     

基于CFRP加固的钢混排架厂房全寿命周期地震成本研究

采用增量动力分析（incremental dynamic analysis,IDA）对坐落于我国西部具体地区的单层钢混排架工业厂房基于碳纤维布（carbon fiber reinforced polymer,CFRP）加固前后的地震损伤和全寿命周期地震成本进行对比计算分析,研究中参考了中国抗震规范和美国太平洋地震工程研究中心（PEER）强震数据库后拟合建立了与分析地区地质场地条件接近的当地地震风险度概率模型。采用多参数混合加权推导计算出CFRP加固钢混排架柱厂房结构全寿命周期地震损失成本统计值,计算过程中的结构尺寸、材料强度、地震荷载等相关参数变量采用蒙特卡洛（MonteCarlo Sampling,MCS）随机样本法予以考虑,研究结果显示该地区CFRP加固单层钢混排架厂房结构全寿命周期地震成本统计中位值在5.75元/（年·m²）,扣除加固材料成本及加工费用后较同类型未加固普通厂房全寿命期地震成本费用综合节省约16.5%,显示厂房采用CFRP加固技术后具有良好的全寿命周期地震成本经济性,同时CFRP加固后的厂房结构地震年平均成本直接费CoV统计偏差在1.35%~1.36%。     

Economic design of water distribution systems in buildings

This article discusses an engineering optimization problem which arises in hydraulics and is related to the use of a new criterion for sizing water distribution piping in large buildings. The optimization model aims to find the most suitable interior pipe diameters for the various pipes in the system, using commercial sizes and minimizing the overall installation cost according to some boundary conditions. The problem is formulated as a non-convex nonlinear program and a branch-and-bound algorithm is introduced for its solution. A procedure is proposed to obtain a feasible solution with standard values from the optimal solution of the non-convex program. The performance of the algorithm is analysed for a real-life problem and the cost of the computed solution is assessed, showing the appropriateness of the model and the optimization techniques.     

挤淤爆破规律及其振动效应研究

为了研究挤淤爆破规律以及爆破地震波的传播特性,结合连云港连云新城示范区填海造地及基础设施建设项目的挤淤爆破工程实例,对挤淤爆破的全过程进行高速摄影录像和爆破地震波监测与分析。高速摄影再现了挤淤爆破过程中"水—淤泥—围堰"系统相互作用的运动过程,有效解释了挤淤爆破过程中预埋石料与淤泥置换的作用机理。利用实测的爆破地震波数据修正与地形地质条件有关的系数K和衰减系数α,获得了适于挤淤爆破过程中计算质点振动速度随距离衰减的Sadovsk计算公式,为有效预测类似工程中爆破地震波的传播规律特征提供了一种方法参考。挤淤爆破过程中测得的爆破地震波主振频率范围在8~50 Hz之内,说明淤泥介质对爆破地震波不同频率成分的传播具有选择性:高频地震波通过淤泥时产生大幅度的衰减,低频地震波通过淤泥后对建(构)筑物造成破坏。     

玄武岩纤维加固震损砌体结构振动台试验研究

地震震害调查表明,砌体结构因抗震性能较差,在地震中更易遭受破坏。玄武岩纤维（BFRP）具有良好的物理、力学性能,且价格低廉,但其在震后受损结构加固中却未得到广泛使用。通过对一栋缩尺比为1:4的三层砌体结构模型预震损及其震损后玄武岩纤维加固的两次振动台试验,对比分析了两次模型试验的动力特性、地震反应和损伤破坏情况,旨在验证玄武岩纤维加固震损砌体的有效性。试验结果表明,玄武岩纤维加固法可以改善砌体的脆性,延缓墙体裂缝的发展,提高结构的整体性和整体刚度,改善结构的耗能能力,使震损加固砌体结构达到甚至超过未震损结构的抗震性能,且不改变原结构质量,是一种非常有效的震损砌体结构加固方法。     

Optimization of laminated composites considering different failure criteria

The purpose of the present work is to analyse how different the optimal structures are when different first ply failure criterion are considered in the optimization of laminated composites. Two problems are solved: the minimum weight and the minimum material cost of laminated plates subjected to in-plane loads. The failure criterion is taken into account by means of constraints introduced in the optimization problem. Three different failure criteria are tested independently: maximum stress, Tsai–Wu and the Puck failure criterion (PFC). Emphasis is given to the PFC as it appears to agree better with practical observations. The design variables are the ply orientations, the number of layers and the layer material, and the optimization problem is solved by a genetic algorithm (GA). The results show that optimal structures highly differ when different failure criterion are considered and that none of the failure criteria is always the most or the least conservative when different load conditions are applied.     

带加强层高层建筑地震作用分析与减震研究

带加强层的高层建筑在地震作用下侧移和内力有特有的规律。针对带加强层高层建筑分析其动力特性和地震作用下的侧移规律,并进行减震效果研究和优化设计,提出设计建议。以某高烈度区一座带加强层高层建筑为例的分析结果表明,带加强层的高层建筑在地震荷载作用下侧移有突变,楼板缺失导致整个结构变形规律发生改变,附加粘滞流体阻尼器后层间位移角和底部剪力都有所减小,减震方案优化后减震效果良好。     

基于细菌觅食和蚁群算法的工艺路线优化

针对工艺路线规划中满足多重约束的最优方案选择问题,提出一种细菌觅食和蚁群优化（bacteria foraging ant colony optimization,BFACO）算法。首先,将工艺路线规划转化为对加工元顺序的优化问题,构造满足多种工艺准则的加工元拓扑优先顺序图,并构建了在缩短加工周期、提高加工质量和降低加工成本目标下的最低加工资源更换成本的目标函数;其次,设计加工元序列与加工资源两个搜索阶段的蚁群搜索,拓扑优先顺序图可弥补加工元序列搜索阶段信息素匮乏的缺点,而在加工资源搜索阶段引入细菌觅食优化算法的复制与趋向操作,可使加工元在多个可选加工资源的情况下获得加工资源更换成本最低的加工序列;最后,基于细菌觅食与蚁群算法的融合优化,完成多个加工元序列的信息素积累并输出最优解,解决蚁群算法局部收敛且计算速度慢的问题。将BFACO算法应用于实例并与其他优化算法的优化结果进行对比,结果显示BFACO算法在工艺路线优化方面较其他优化算法具有较高的计算效率,验证了BFACO算法的可行性与有效性。研究表明,BFACO算法可有效应用于同时考虑工艺约束与加工资源更换成本的工艺规划,为实际生产提供高效且灵活的工艺路线的优化选择。     

外加钢筋混凝土梁柱砖砌体房屋抗震性能试验研究

分别对外加钢筋混凝土梁柱加固的砖砌体结构、未采取抗震设防措施的普通砖砌体结构、按现行抗震规范要求设置构造柱和圈梁的砖砌体结构进行了拟动力抗震试验和低周反复加载试验,对比研究了这三类结构的破坏形态、滞回曲线、骨架曲线、极限承载力、极限变形及刚度退化曲线等特性。研究表明,经外加钢筋混凝土梁柱加固的砖砌体房屋能满足现行抗震规范的设防标准要求,外加的钢筋混凝土梁和柱能有效约束墙体和预制板,提高砖砌体结构的承载力和变形能力,并延缓结构的刚度下降。     

A portfolio approach to maintenance: a case study of a residential estate

The choice between repairing and replacing a defective piece of equipment is an economic decision that is faced by all maintenance managers, including housing estate managers. Such decisions need to be made within the limits and constraints set by maintenance expenditure budgets and by manpower availability. Our particular problem is concerned with the development of a maintenance policy for a residential estate of the Hong Kong Housing Authority. Our approach is to treat the numerous housing systems as a portfolio and to exploit flexibilities in performing or delaying the repair/replacement of these systems. The cost of a repair/replacement plan for the portfolio is formulated as an integer programme and genetic algorithms (GAs) are employed to generate optimal and sub‐optimal solution plans. The novel features of the approach are the model developed and use of GAs in this particular optimization context. The results and discussion of the case study will help practitioners to better understand the difficulties involved in collecting relevant cost data and in formulating repair/replacement plans for a group of buildings. Copyright © 2007 John Wiley & Sons, Ltd.     

基于地震碰撞易损性的相邻结构临界间距研究

提出了一种基于近似解析的地震碰撞易损性确定相邻结构临界间距的方法。首先根据基于性能的抗震设计理论,将碰撞事件表示为单势垒首次超限可靠度问题;其次,通过随机振动理论得到不同地震动强度下结构体系的条件失效概率;然后,结合相邻结构的地震碰撞易损性,将临界间距的计算表述为逆可靠性问题,求出在结构设计使用年限内,某一具体目标碰撞概率所对应的临界间距值,通过蒙特卡洛数值模拟方法进行的相关验证,证实了上述理论的适用性与有效性。     

LNG装置经济性比较的综合性原则

设计和选定液化天然气装置的经济性评估常常是ＬＮＧ装置选择的决定性因素。使用最小成本指标准则不仅考虑了运行成本，投资成本，而且还考虑了比能耗，循环流程压力。工艺方案控制的复杂性和设备可靠性方面的影响。使用这种方法不仅能在最初设计阶段估处生产成本和利润指标，而且可以在参数优化，流程变型和机组设备选择的过程中，对各种变化的经济性迅速地进行客观比较。     

基于当前节能标准公共建筑空调综合能效比分析

基于国家当前执行的公共建筑节能标准,评价分析了当前节能标准对于中央空调系统综合能效比适用范围,通过计算分析得出：现行国家标准对于公共建筑中央空调系统最低能效比约束值为2．67W/W,本文对于评价新建筑建筑空调系统能效比和既有建筑空调系统节能运营提供了可靠的技术数据支撑。     

简化的测量过程统计控制方法

休哈特控制图平均值控制界限的设置对于计量标准或测量设备来说有很大的局限性,根据计量标准或测量设备的特点,提出简化的测量过程统计控制方法,该方法省去了标准偏差或极差控制图。根据标准偏差试验结果的大小,提出了子组最少测量次数的确定方法,平均值控制界限以各组平均值算得的标准偏差来设置,平均值控制图异常的判断准则简化为3种判据,进而大大减少了实施统计控制的工作量,便于推广应用。     

Equivalence of cost generators for minimum cost flow phase unwrapping.

Phase unwrapping represents a crucial step in processing phase data obtained with techniques such as synthetic aperture radar interferometry, speckle interferometry, and magnetic resonance imaging. The so-called branch-cut approaches form an important class of phase unwrapping algorithms. In 1996, Costantini proposed to transform the problem of correctly placing branch cuts into a minimum cost flow problem [Proceedings of the Fringe '96 Workshop (European Space Agency, Munich, 1996), pp. 261-272]. The critical point of this new approach is to generate cost functions that have to represent all the a priori knowledge necessary for phase unwrapping. Any function transforming a priori knowledge into a cost function is called a cost generator. Several types of algorithms ranging from heuristic approaches to generators based on probability-theory interpretations were suggested. A problem arising from the growing diversity of algorithms is to find a criterion for the equivalence of different cost generators. Two cost generators are equivalent if they produce cost functions with the same minimal flow for every residue configuration on every image with all possible a priori knowledge. Comparing the results of different cost generators on test scenes can show only their non-equivalence. We solve this problem by proving the following mathematical classification theorem: Two cost generators are equivalent if and only if one can be transformed into the other by multiplication by a fixed constant.     

Quality control for a detected an appropriate queue from K-independent M/M/C/N queueing models

In this paper, we consider a system of K-independent Markovian queues such that each one of them has a Poisson arrival process and exponential service time. We assume that every server has some characteristics such as the speed of the service performance or the service cost. To find an appropriate queue, which meets customer needs for the service performance, we present a new approach that gives a suitable decision to choose an appropriate queue from our system. This allows the customer to deal with minimum cost and faster server under steady state. We solve an interesting discrete stochastic optimization problem where the paid cost by the customer is bounded by a Gaussian distribution. Using these hypotheses, we perform a simulation study by generating the paid cost random values and choosing the minimum value between them. This minimum cost gives the highest service rate, which is used to obtain the optimum values of the system effectiveness measures.     

预应力碳纤维条带加固混凝土圆柱的地震损伤模型

为了研究预应力碳纤维条带加固混凝土圆柱的地震损伤性能,利用包括对比柱在内的13根混凝土圆柱试验数据,对修正的Park-Ang损伤模型进行改进,建立了预应力碳纤维条带加固混凝土圆柱的地震损伤模型;根据试件的轴压比、纵向配筋率、考虑了预应力碳纤维条带及箍筋的双重横向约束作用对组合参数进行非线性回归分析,得到了该文推荐模型中组合参数的经验表达式;基于所提出的地震损伤模型,计算出了不同损伤状态的特征点所对应的地震损伤指标,据此给出了预应力CFRP加固混凝土圆柱的抗震分级标准;有限元分析得到的CFRP加固混凝土圆柱的损伤指标与试验结果基本符合,证明了该损伤模型以及加固柱的抗震等级划分标准的合理性。     

Equipment scheduling at mail processing and distribution centers

Mail Processing and Distribution Centers (P&DCs) run 24 hours a day, 7 days a week and are staffed by a skilled complement of full-time, part-time, and temporary employees. A recurrent problem faced by facility managers involves the development of daily schedules for the automation equipment used to process the mail. The ultimate goal is to minimize the labor costs associated with running the facility while ensuring that all service standards are met. The focus of this paper is on the equipment scheduling aspect of the problem. In particular, we seek a weekly schedule that satisfies all operational, technological, and legal constraints of the system at a minimum cost. The problem is modeled as a large-scale mixed-integer linear program and solved sequentially using a three-stage methodology. In each stage, a separate criterion is optimized and the corresponding objective function value is used as a constraint in subsequent stages. To ease the computational burden, two major enhancements are developed. The first is a pre-processor designed to reduce the number of integer variables; the second is a heuristic that uses the linear programming solution as a target and attempts to find a feasible integer point as close to it as possible. The methodology is demonstrated with data obtained from the Dallas P&DC. The computations indicate that for letter operations alone the annual savings will be on the order of $1.6 million per facility when the system is implemented nationwide over the next 3 years.     

Optimization of cost and downtime for replacement model following the expiration of warranty

This paper deals with the optimal replacement policies following the expiration of warranty: renewing warranty and non-renewing warranty. If the system fails during its warranty period, it is replaced with a new one and if the system fails after the warranty period is expired, then it is minimally repaired at each failure. The criterion used to determine the optimality of the replacement period is the overall value function, which is established based on the expected downtime and the expected cost rate combined. Firstly, we develop the expected downtime per unit time and the expected cost rate per unit time for our replacement model when the cost and downtime structures of maintaining the system are given. The overall value function suggested by Jiang and Ji [Age replacement policy: a multi-attribute value model. Reliab Eng Syst Saf 2002;76:311–8] is then utilized to determine the optimal maintenance period based on the expected downtime and the expected cost rate. Numerical examples are presented for illustrative purpose.