Alternative Resilience Indices for City Ecosystems Subjected to Natural Hazards

Prompt and efficient responses against natural hazards are needed to build cities capable of withstanding disasters, namely resilient cities. This study aims at presenting and testing synthetic resilience indices over a real urban center threatened by multiple hazards, for which a global overview of city performance is requested. An integrated framework is proposed for quantitative resilience assessment by way of time‐independent synthetic indices. The approach proposed is in accordance to the complex network theory and uses a global indicator of the system connectivity to assess the city functioning also in case of network disruption. Resilience is evaluated as a proxy for systemic urban damage by modeling a city ecosystem as a hybrid social–physical network. Seismic and landslide scenario analyses are performed for the city of Sarno, Italy. A probability‐based approach is used to compute urban vulnerability. Subsequently, to highlight changes in results according to the type of disaster, a recovery strategy is simulated to assess efficiency and damage states in each recovery stage, and urban resilience.     

The efficiency of postal services in the age of market liberalization and the internet: Evidence from Central and Eastern Europe

The rise in electronic communications and the recent liberalization of the postal market in the European Union have put national postal-service providers in Central and Eastern Europe (CEE) under pressure to restructure and optimize their operations. The paper employs non-parametric methods to measure the relative technical and cost efficiency of CEE postal operators in terms of quantity-based and quality-based output indicators. The results indicate that inefficiency varies between 20% and 30%. Regression analysis attributes efficiency gains to increased competition, institutional reforms, less burdensome customs procedures, and population density, while use of electronic mail was negatively related to postal-service efficiency.     

一体化涡旋网格澄清工艺的研制与应用

一体化涡旋网格澄清工艺是基于微涡旋混凝技术及浅池理论而提出的。该反应器在絮凝反应单元设置了涡旋网格絮凝反应器,在澄清分离室内设置了斜管(或斜板)沉淀器,增设了污泥浓缩单元,采用低回流或无回流技术,改进喷嘴及喉管结构,加大反应室的容积利用率,降低了能耗。工程实践表明,该工艺不仅提高了净水工艺的絮凝反应效率、降低了药耗、改善了净水水质,而且还提高了沉淀分离效率和污泥含固率,具有节省整体工程投资、降低制水成本等优点。     

Strategies to reduce postal network access points: from demographic to spatial distribution criteria

The wide diffusion of digital technologies has produced a sharp decline in letter mail volumes. In this context, postboxes are mostly underutilized, and postal operators are pushing toward a re-discussion of their distribution criteria with the National Regulation Authorities, to reduce their number. In this work, we propose two alternative strategies to support this process, and we evaluate the impact produced by their implementation on the accessibility of users to the postal network. Results obtained from an extensive application to the Italian case prove the capability of the proposed approach to provide insightful managerial and policy implications.     

Seismic design of water distribution networks using auto-generation techniques

A feasible approach that uses an auto-generation technique is proposed to design and retrofit water distribution networks (WDNs) subjected to earthquakes. Because pipelines are laid along roads, the road information is extracted and then integrated into the auto-generation technique whereby the rules relevant to laying the pipelines are established. An optimisation model with parameters of network topology and pipeline diameter is developed to design and retrofit WDNs, whose seismic functional reliability index serves as a constraint. An intelligent optimisation program via a particle swarm algorithm is employed to generate the optimal network after a number of evaluations and evolutions. For illustrative purposes, a hypothetical and a real WDN model are investigated, respectively. Numerical results indicate that the optimisation and design method developed in this paper provides a new perspective towards the rational balance between risk and investment.     

基于MAXScript的城市综合管网批量建模方法

针对城市综合管网三维建模过程中手工建模方法效率低,而完全从底层开发或基于商业软件进行二次开发实现管网建模具有成本高、周期长及成果可移植性差等缺点,提出一种在3ds Max软件环境下,基于MAXScript脚本语言进行管线和附属设施批量建模的技术方法,实现了城市综合管网的整体自动建模,所建模型可转换为OSG、3DS等通用的三维数据交换格式,可方便地实现数据共享和重复利用。最后对该建模方法进行了生产实例验证,并将生成的三维管网模型导入Arc GIS平台进行属性挂接和数据管理,结果表明该方法简单、可靠,在一定程度上节约了三维管网数据建设的时间和成本。     

Dynamic modeling of the quantitative risk allocation in construction projects

Allocation of construction risks between owners and their contractors has a significant impact on the total construction costs. This research presents an integrated fuzzy-system dynamics approach for quantitative risk allocation. All the factors affecting the risk allocation process are modeled using system dynamics approach. Fuzzy logic is integrated into system dynamics modeling structure to account for the existing uncertainties. The values of different factors that have an uncertain nature are determined by fuzzy numbers. The application of Zadeh's extension principle and interval arithmetic is proposed for the system dynamics to enable the system outcomes to be presented considering uncertainties in the input variables. Using the proposed integrated fuzzy-SD model, the project cost is simulated at different percentages of risk allocation. The optimum percentage of risk allocation is determined as a point in which the project cost is minimized. The performance of the proposed method is assessed by employing the method in a tunneling project.     

Electricity distribution tariffs and distributed generation: Quantifying cross-subsidies from consumers to prosumers

An increasing amount of distributed generation (DG) can cause an increase or a decrease on distribution network costs. Tariff design is the main tool for allocating these costs to customers who own and operate DG resources.Currently, however, either DG units are exempt from paying distribution tariffs or they are subject to tariffs originally designed according to a traditional pricing model without DG in the grids, also known as load-based pricing. Partial recovery of the allowed distribution company revenue requirements or cross-subsidies between customers may ensue from such tariff arrangements.In this article, pricing, as represented by a combination of net metering and pure volumetric tariffs, is applied in the context of increasing DG. The paper presents a methodology where a Reference Network Model (RNM) is used to investigate the effect of this pricing scheme on the magnitude of cross-subsidies from consumers towards the so-called prosumers for a set of twelve simulations based on real-size networks in the U.S.For the considered scenarios, the analysis reveals substantial cross-subsidies from consumers toward prosumers. The degree of subsidy varies with the amount of DG connected to the grid and network characteristics. The rate of cross-subsidy tends to be higher for low-density grids.This paper contributes to the net metering literature with a quantitative assessment of cross-subsidies by comparing allocated payments to different actors with the costs they impose on the system, estimated through an RNM. Moreover, the paper proposed a tariff structure based on cost causality by proposing a cost-reflective, volumetric tariff approach through which aggregate load-driven and DG-driven network costs are accordingly allocated to loads and DG units.     

Handling construction pollutions using multi‐objective optimization

Quantitative assessment of emissions associated with construction projects should be carried out during the planning phase of the projects. This is important to detect and highlight any excesses of residuals during the construction phase. A newly developed framework is proposed to handle construction pollution using multi‐objective optimization. The approach, utilized by the proposed framework, is based on calculating the generated pollution for each activity involved in the project, as a result of dust, harmful gases and noise. The results of the quantitative assessment are integrated in a utility function that expresses the amount of total pollution. Then, evolutionary genetic algorithms (GAs) are used to carry multi‐objective optimization, considering three objective functions (project duration, project cost and total pollution). The proposed application considers the dynamic nature of construction activities including different types of relationships and the change of activities' criticality. An actual case study is worked out to demonstrate the practical use of the proposed framework and to investigate the sensitivity of its parameters.     

三维GIS在地铁车站综合管网设计中的应用研究

为了提高地铁车站综合管网的设计质量和效率,以虚拟现实技术为指导,自主研发了基于三维GIS平台的地铁车站综合管网信息系统。该系统以信息统筹管理、多信息数据集成、智能分析为设计目标,由数据层、逻辑层和应用层构成系统逻辑结构,其主要功能有图纸管理、图库管理、碰撞冲突分析、剖面功能、路径漫游和模型调整。以工程实际应用为依托,构建了基于三维GIS应用的地铁车站综合管网设计组织结构与协作模式。实践表明,三维GIS技术在地铁车站综合管网设计中的优势突出表现为突破设计难点、积累项目信息与节省建设成本,可为相关工程应用提供借鉴。     

Robotic tile placement: Tools,techniques and feasibility

The project develops an integrated digital workflow [1] for robotic tile placement that allows off-site use of industrial robotics for on-site tiled surfaces, and tests feasibility in the context of the tile industry. The proposed approach overcomes limitations of existing methods that focus on efficiency [2,3] by enabling unique and complex tile patterns. A design experiment is used during the development of computational and robotic technologies. Integration and industry implementation were studied through interviews with experts, field studies, and literature research that included a review of U.S. tile installation standards [4]. A Rhinoceros™ based digital workflow was developed that includes complex pattern generation, integrated robotic programming and simulation, and cost/time estimation. The paper describes strategies for pre-tiled panels, recommends specific material combinations, and includes basic cost estimation in the context of construction. Robotic tile placement ultimately adds value by moving installation of tile patterns to the place of tile production.     

Hybrid approach for congestion management using optimal placement of distributed generator

Congestion management (CM) in a large power system network is a difficult task which can be solved by placing one or more distributed generators (DGs) on congested lines. The first concern is to determine the exact location of congested line for the placement of optimal size of DG so that cost can be minimised. In this work, hybridisation of firefly technique and differential evolution optimisation search has been proposed, which manages congestion effectively by rescheduling of generators satisfying the system constraints both technically and economically in the deregulated market scenario. To validate the proposed hybrid approach, results have been compared with firefly optimisation technique results. It is observed that the hybrid approach is an efficient tool in handling CM resulting in a secure operation to reduce flows in the heavily loaded lines with low system loss and increasing power capability with improved stability of network by controlling power flows in the network.     

高层建筑结构随机振动的最优阻尼器控制策略

提出考虑阻尼器布置与阻尼器参数同步优化的高层建筑结构随机最优控制方法。为有效地寻找每个序列工况的阻尼器最优拓扑和阻尼器最优参数,分别定义了基于超越概率的层可控指标梯度最小准则和能量均衡最优准则。上述控制准则内蕴了系统安全性、系统服务性、系统舒适性、阻尼器工作性以及它们之间的均衡。以随机地震动作用下十层剪切型框架结构的黏滞阻尼器最优控制为例进行分析,结果表明,采用该方法可以以最小的投资获得最大的控制效益,受控后结构反应沿层分布较受控前更均匀、能达到所期望的结构性态。     

Strategic network expansion of urban rapid transit systems: A bi‐objective programming model

With the development of urbanization and the extension of city boundaries, the expansion of rapid transit systems based on the existing lines becomes an essential issue in urban transportation systems. In this study, the network expansion problem is formulated as a bi‐objective programming model to minimize the construction cost and maximize the total travel demand covered by the newly introduced transit lines. To solve the bi‐objective mixed‐integer linear program, an approach called minimum distance to the utopia point is applied. Thus, the specific trade‐off is suggested to the decision makers instead of a series of optimal solutions. A real‐world case study based on the metro network in Wuxi, China, is conducted, and the results demonstrate the effectiveness and efficiency of the proposed model and solution method. It is found that the utopia method can not only provide a reasonable connecting pattern of the network expansion problem but also identify the corridors with high priority under the limited budget condition.     

Joint column generation and Lagrangian relaxation technique for incident respondent location and allocation

Incident response operations require effective planning of resources to ensure timely clearance of roadways and avoidance of secondary incidents. This study formulates a mixed-integer linear program to minimize the total expected travel time and maximize the demand covered. The model accounts for the location, severity, frequency of incidents, dispatching locations, and availability of incident respondents. An integrated methodology that includes column generation and Lagrangian relaxation with a density-based clustering technique that defines incident hot spots is proposed. The hybrid approach is applied to an empirical case study in Raleigh, NC. A network instance with 10,672 incident sites, clustered with a search distance (ε) of 5 min, is solved efficiently with an optimality gap of 1.37% in 2 min. A Benders decomposition technique is implemented to conduct benchmark analyses. The numerical results suggest that the proposed algorithm can solve the problem efficiently and outperform the benchmark solutions.     

Using the MD CAD model to develop the time–cost integrated schedule for construction projects

Time and cost are two critical factors determining the success of a construction project. However, it is still a daunting task for project planners to develop a time–cost integrated schedule due to the tremendous amount of information that need to be processed. Various research efforts have been made to develop model-based systems to facilitate information processing and integrate time and cost throughout the project life cycle. However, the results of the previous studies are not comprehensive enough to fulfill the requirements of project management. This paper presents a scheduling system that applies Multi-Dimensional (MD) CAD model, Object Sequencing Matrix (OSM), and genetic algorithms (GAs) to generate the time–cost integrated schedule for the construction project. A computer implementation called MD CAD model-based Project Scheduling System (MD_PSS) is also developed to verify the feasibility of the proposed approach.     

基于径向基神经网络的基坑支护位移预测方法

简要分析了径向基神经网络相对于BP神经网络的优点,利用径向基神经网络建立了基坑支护水平位移的预测方法并编制了基于径向基神经网络的支护位移预测程序.结合实际工程监测数据中的基坑支护结构水平位移数据,对网络进行训练并利用训练好的网络对基坑支护结构的水平位移进行了预测.从预测结果与实测结果的对比分析来看,利用径向基神经网络对基坑支护水平位移进行预测是可行的,其精度符合工程实际的要求.     

冷热电联供系统能耗与CO2排放特性分析

建立了微型燃气轮机冷热电联供系统数学优化模型。基于上海某办公楼典型日负荷结构,以总运行费用最低为优化目标,采用模式搜索法对数学优化模型进行求解计算,分析了微型燃气轮机发电效率及空燃比对联供系统能耗与CO2排放特性的影响。研究结果表明微型燃气轮机发电效率及空燃比对联供系统能耗与CO2排放的影响趋势是一致的,可以通过调节微型燃气轮机发电效率及空燃比来充分发挥联供系统节能性和环保性的优势。     

Risk-based group decision making regarding renewable energy schemes using a stochastic graphical matrix model

Improvements to sustainability are generally measurable based on their environmental, economic, and socio-cultural effects. This study applied this concept by developing and empirically testing a risk-based method for assessing renewable energy policy. An integrated theoretical framework is proposed for analyzing group decision-making regarding renewable energy (RE) policy selection. The proposed graphical matrix approach combined with Monte Carlo simulation compares alternative RE schemes by identifying and measuring critical performance indicators with acceptable reliability. The mathematical model reliably prioritizes alternatives using majority voting to address uncertainty in multi-criteria decision making process. A case study using historical data from previous RE development projects to confirm the feasibility of this approach. Compared to the conventional deterministic method, the stochastic graphical matrix approach provides more reliable estimation accuracy, decision quality, and efficiency in selection of sustainable renewable energy. The systematic approach provides policy makers information for use in evaluation by synthesizing the judgments of a panel of experts.     

Thermo-economic optimization of rooftop unit’s evaporator coil for energy efficiency and thermal comfort

In this paper, the optimization-simulation approach is proposed to investigate energy saving potential of an air-cooled direct expansion rooftop package air conditioning system by refining the model of the HVAC system components and deriving optimal configuration for evaporator coil subject to technical constraints. In this method the frontal area of the evaporator coil is maintained as constant and the variation of other geometrical parameters on the thermal and economical performance of the system is investigated. An actual air-cooled rooftop package of a real-world commercial building in hot and dry climate conditions is used for experimental data collection. Both inputs and outputs are measured from the field monitoring in two summer weeks. Based on the mathematical models and using collected data, modules incorporating the proposed optimal redesign procedure were embedded in a transient simulation tool. A mixed heuristic- deterministic optimization algorithm was implemented in the transient tool to determine the synthesis and design variables that influence the cost and energy efficiency of each configuration. Available experimental results were compared to predicted results to validate the model. Afterwards, the computer model was used to predict how changes in cooling coil geometry would affect the building thermal comfort, the cost and energy consumption of the system.