Development of an integrated modeling system for improved multi-objective reservoir operation

Reservoir is an efficient way for flood control and improving all sectors related to water resources in the integrated water resources management. Moreover, multiobjective reservoir plays a significant role in the development of a country’s economy especially in developing countries. All multi-objective reservoirs have conflicts and disputes in flood control and water use, which makes the operator a great challenge in the decision of reservoir operation. For improved multi-objective reservoir operation, an integrated modeling system has been developed by incorporating a global optimization system (SCE-UA) into a distributed biosphere hydrological model (WEB-DHM) coupled with the reservoir routing module. The new integrated modeling system has been tested in the Da River subbasin of the Red River and showed the capability of reproducing observed reservoir inflows and optimizing the multi-objective reservoir operation. First, the WEB-DHM was calibrated for the inflows to the Hoa Binh Reservoir in the Da River. Second, the WEB-DHM coupled with the reservoir routing module was tested by simulating the reservoir water level, when using the observed dam outflows as the reservoir release. Third, the new integrated modeling system was evaluated by optimizing the operation rule of the Hoa Binh Reservoir from 1 June to 28 July 2006, which covered the annual largest flood peak. By using the optimal rule for the reservoir operation, the annual largest flood peak at downstream control point (Ben Ngoc station) was successfully reduced (by about 2.4 m for water level and 2500 m³·s⁻¹ for discharge); while after the simulation periods, the reservoir water level was increased by about 20 m that could supply future water use.     

Designing an expert system for real-time reservoir system operation

Significant progress has been made recently in the design of optimization models to mimic the decision making process of reservoir operators. Several of these models for real-time, short term reservoir system operation are described. The models include: an optimization model constructed specifically for a multi-reservoir, multipurpose system in Kentucky; a goal programming model that requires less information than most other models yet may yield equivalent or better results; a chance constrained model that explicitly considers errors in streamflow forecasts in the operating environment; and a balancing model that uses cumulative distribution functions to maintain a balance between storage, release, and any other characteristic of the operation. Each model is briefly described and comparisons between models are made. These models represent the initial development of an expert system for real-time reservoir system operation.     

多目标遗传算法用于给水管网优化设计的研究

建立了一个基于经济性和可靠性的多目标数学模型用于给水管网优化设计。利用惩罚函数法对遗传算法进行改进后,应用其对多目标数学模型进行求解,并将该优化方法运用于实际工程。结果表明,采用多目标遗传算法得出的结果优于常规优化方法。     

A multi-objective structural optimization method for serviceability design of tall buildings

Structural optimization design aims to identify optimal design variables corresponding to a minimum objective function with constraints on performance requirements. To this end, many optimization frameworks have been proposed to determine optimal structural systems that are subjected to seismic and wind hazards in isolation. However, some modern tall buildings are sensitive to seismic and wind excitation owing to their complex structural systems and geographic regions. Therefore, a proper structural optimization method for such buildings is required to ensure that the expected performance is achieved in a multi-hazard scenario. This study proposes a multi-objective serviceability design optimization methodology for buildings in multi-hazard seismic and wind environments by combining optimality criteria and the nondominated sorting genetic algorithm II (NSGA-II). Seismic and wind effects can be instantaneously updated due to changes in the structural dynamic properties during the optimal design process. A neural-network-based surrogate model with self-updating is proposed to predict the structural natural frequency so that the overall computation time of the optimization process can be reduced. The proposed method was used to optimize a 50-story frame-tube building and was compared against the general genetic algorithm and general NSGA-II to verify the feasibility and effectiveness.     

Comparison of stochastic and fuzzy dynamic programming models for the operation of a multipurpose reservoir

Reservoir management is a highly complex problem, which includes the uncertainty in the inflows as well as in the objectives. Stochastic dynamic programming (SDP) has been widely used to develop the optimal operating policies of multipurpose reservoirs. In the recent years, fuzzy optimization has been used to incorporate the uncertainty caused due to the imprecise nature of objectives. In the present study, a comparison is made between a conventional SDP model and fuzzy dynamic programming models for optimal operation of a multipurpose reservoir. The two models are developed for Hirakud Reservoir on River Mahanadi in the State of Orissa in India. The performance of the reservoir is evaluated under the operating policies derived from these models through simulation. The results indicate that the fuzzy dynamic programming model performs better in achieving the flood control objective and thus in the overall performan1ce of reservoir.     

An optimization model for water quantity and quality integrated management of an urban lake in a water deficient city

This paper presents an optimization model for water quantity and quality integrated management of an urban lake in a water deficient city. A representative water quantity and quality safeguard system served urban lake, including multi-source water supply facilities, recirculating water purification facilities and surplus water discharge facilities, is widely used in Chinese water deficient cities. Because it is complicated, any mismanagement will result in water quality deterioration, water waste and high operation cost. The presented model attempts to achieve the objectives of controlling water pollution, reducing economic cost and improving water utilization efficiency through an optimized operating water safeguard system. The model is applied to Qingjing Lake in Tianjin, China. Results show that the model plays a more positive role for water quantity and quality integrated management.     

臭氧预氧化强化混凝处理引黄水库水的中试研究

针对引黄水库水的特点,采用臭氧预氧化强化常规工艺处理引黄水库水。中试研究结果表明:臭氧预氧化能够降低常规工艺出水浊度,改善对有机物的去除效果,同时提高常规工艺对氨氮和藻类的去除率。适宜的臭氧投加量为1～2mg/L,当臭氧投加量为1mg/L时,臭氧预氧化后,滤后水浊度、CODMn、UV254、氨氮和叶绿素a的去除率,与常规工艺相比分别提高了2.7,2.5,7.8,5.2和4.8个百分点。     

A framework for an automated and integrated project monitoring and control system for steel fabrication projects

This paper presents an automated and integrated project monitoring and control framework that facilitates decision making by enabling project managers to take corrective actions immediately after deviations occur and to mitigate potential damage to ongoing steel fabrication projects. An automated data acquisition system integrated with computer simulation provides a reliable platform for the proposed framework, as the former reduces the time required to obtain as-built data while the latter simulates different scenarios for possible corrective actions in advance. The framework employs High Level Architecture (HLA) as its infrastructure and is composed of several individual monitoring and control components which cooperate and interact with each other in real-time within a unified environment. To verify the concept and test the feasibility of this framework, a model consisting of several components, including automated data capturing, simulation, and visualization, was developed and implemented in the fabrication phase of steel construction.     

Development and identification of an integrated waterworks model for trihalomethanes simulation

To evaluate the impact that new trihalomethanes (THMs) regulations will have on the performance of conventional waterworks in China, we developed an integrated waterworks model to simulate the dynamic behavior of THMs and other associated components, e.g. organic matter, ammonia, and residual chlorine, throughout the conventional water treatment process, which included pre-chlorination, coagulation-flocculation, sedimentation, filtration and post-chlorination. A comprehensive kinetic scheme that takes into account both the physical and biological mechanisms involved in the water treatment processes and the chemical reactions that result from chlorination was proposed for model conceptualization. In addition, the Petersen matrix was designed to present the model and formulate the mass balance equations for the model variables. The model was then identified using the Hornberger-Spear-Young (HSY) algorithm and tested against field data from the Qingzhou Waterworks in Macao, China. Despite gross uncertainty associated with the field data, the model could generally provide good predictions of the simulated variables and meet the management purposes. Furthermore, the identified model parameters agreed well with values that were reported in the literature and could be reasonably interpreted.     

臭氧——浮滤池工艺强化处理引黄水库水中有机物的试验研究

分别采用预臭氧-浮滤池工艺和臭氧气浮-浮滤池工艺对鹊山水库水进行了试验研究.预臭氧-浮滤池工艺试验结果表明,臭氧预处理对浊度去除影响不大;臭氧预氧化对UV<,254>的去除效率很高,平均去除率为76.47%,经气浮、活性炭过滤之后,总去除率可达到100%;臭氧预氧化对COD<,Mn>有一定的去除效果,总去除率较无臭氧预处理平均提高7.0%,出水平均值降至1.87 mg/L.臭氧气浮-浮滤池工艺试验表明,臭氧气浮对浊度去除影响不大,臭氧的强氧化性主要表现在对UV254的去除上,其平均去除率比浮滤池工艺提高了9.8%.     

Monitoring results of an interior sun protection system with integrated latent heat storage

An interior sun protection system consisting of vertical slats filled with phase change material (PCM) was monitored from winter 2008 until summer 2010. While conventional interior sun protection systems often heat up to temperatures of 40 °C or more, the monitoring results show that the surface temperature on the interior side of the PCM-filled slats hardly ever exceeded the PCM melting temperature of 28 °C even in case of long-term intense solar radiation. As long as the PCM is not fully melted, the latent heat storage effect reduces the solar heat gain coefficient (g-value) of the sun protection system to 0.25 for a totally closed blind, and 0.30 for slats set at 45° (the g-values of the same system without PCM are 0.35 and 0.41, respectively). This reduced the maximum air temperature in the offices by up to 2 K in contrast to a reference room with a comparable conventional blind. The sun protection system with PCM therefore considerably improves thermal comfort. In order to discharge the PCM, the stored heat must be dissipated during the night. In climates with sufficiently low outside air temperatures, this is best achieved using a ventilation system in combination with tilted windows.     

Generic creep behavior and creep modeling of an aged surface support liner under tension

Polymer-based materials have been motivated to be an alternative support system element in the mining/tunneling industry due to their logistic and geotechnical benefits. Thin spray-on liner (TSL), a term to define the application of the material on the rock surface with a layer ranging from 2 mm to 10 mm in thickness, shows some promising results. TSLs are mainly composed of plastic, polymer, or cement-based ingredients to a certain proportion. This study intends to reveal the time-dependent response of TSL specimens, cured throughout 500 d, under four constant stress levels for stable laboratory conditions. The results were correlated using two interrelated equations to predict the material's service life (creep-rupture envelopes). The proposed correlations offered an insight into both the effective permanent support time and the strain amount at the liner failure. The time-dependent deformation of TSL, whose performance is highly responsive to creep behavior, was obtained so that the design engineers may use the findings to avoid the severe problems of material creep. Experimental data were also used to develop a Burgers (four-element) creep model. Since the liner has a nonlinear time-dependent behavior, creep models were built for each stress level separately. Subsequently, a generic equation was obtained using the nonlinear parametric dependencies. There is a good agreement between the proposed model and the experimental results. The proposed model can be used as a basis for future numerical studies related to the support behavior of aged surface support liners.     

Development of an integrated structural health monitoring system for bridge structures in operational conditions

This paper presents an overview of development of an integrated structural health monitoring system. The integrated system includes vibration and guided-wave based structural health monitoring. It integrates the real-time heterogeneous sensor data acquiring system, data analysis and interpretation, physical-based numerical simulation of complex structural system under operational conditions and structural evaluation. The study is mainly focused on developing: integrated sensor technology, integrated structural damage identification with operational loads monitoring, and integrated structural evaluation with results from system identification. Numerical simulation and its implementation in laboratory show that the system is effective and reliable to detect local damage and global conditions of bridge structures.     

低影响开发设施组合的水文模拟及不确定性分析

在海绵城市建设中,通过多种低影响开发(LID)设施的组合应用可实现对城市雨水径流的调控。针对LID设施组合的水文模拟存在高维参数估值不确定性分析的难题,以深圳环保产业园LID示范区为例,构建LID组合设施的暴雨洪水管理模型(SWMM),结合Morris筛选法与DREAM算法,对不同降雨条件下模型中不同设施、不同类型参数的灵敏度和不确定性进行分析。结果表明,位于下游的设施参数灵敏度普遍高于上游设施,排水及导水相关参数灵敏度相对较高;下游设施的排水参数后验分布峰值明显,参数不确定性小;中等强度降雨事件模拟结果的不确定性比高强度降雨事件要小。     

基于 NSGA-II 算法的集雨型绿地低影响开发设施规模优化计算方法及应用 ——以南阳院士小镇为例

目前,在集雨型绿地设计过程中,进行低影响开发（low impact development,简称LID）设施规模设计时存在目标单一、缺乏可量化规模依据等现象,且布设效率低下,雨洪模拟和设计流程衔接不畅。在参数化设计平台Grasshopper中建立多目标优化平台,以雨洪控制效果和建设成本为目标,运用NSGA-II算法对LID设施规模变量进行优化求解,从而在设计前期为LID设施规模设计提供定量依据。在此基础上,将研究成果应用于南阳院士小镇集雨型绿地设计项目,并与传统开发方法进行比较,结果表明该优化计算方法可高效地为LID设施规模设计提供科学的定量依据。根据计算结果,发现在研究区选用的LID设施组合条件下,LID设施的建设成本和雨洪控制效益符合边际递减规律,因此LID设施规模须与海绵规划要求匹配,在一定条件下,适当提升透水铺装和生物滞留设施的比例有利于提升LID设施的性价比。研究成果可以为今后集雨型绿地设计提供新思路。     

Optimal joint deployment of flow and pressure sensors for leak identification in water distribution networks

ABSTRACT

A multi-objective optimization methodology is proposed herein for accurate identification of leakage in water distribution networks (WDNs) using pressure and flow sensors. We first model leakage at potential nodes using the EPANET software, and then divide WDN into near-homogenous zones using k-means clustering algorithm based on geographic distribution of nodes. Finally, flow and pressure sensors locations are optimized using the NSGA-II algorithm to identify the leakage zone accurately. Novelty of the proposed approach lies in sequential optimization of flow and pressure sensors placement, which helps improve the accuracy of leakage zone identification in WDNs. The objective functions of this study are: 1) maximizing accuracy of identified leakage zone and 2) minimizing number of sensors (and hence operational costs). Simulation results of the Mesopolis WDN corroborate the efficiency and effectiveness of the proposed approach.     

寒区高速铁路隧道温度场模型试验系统的研制及应用

 基于寒区高速铁路隧道温度场研究现状及存在问题,以俄罗斯400 km/h的莫喀高铁隧道防寒保温设计为研究对象,研制不同洞外气温、围岩地温、列车运行速度和运行间隔等条件下寒区高速铁路隧道的温度场模型试验系统。该系统由高速列车模型驱动装置、隧道模型、温度控制装置、测试系统以及列车模型五部分组成：高速列车模型驱动装置采用伺服电机,通过PLC梯形图语言编程技术实现列车模型加速、匀速和减速过程的精确控制;隧道模型主体材料采用有机玻璃,通过法兰、螺栓和密封条连接而成,整个试验过程可视化并兼具美观性,还可根据试验需求通过预留多组螺栓孔实现纵向尺寸的拓展,从而模拟不同长度的隧道;温度控制装置由洞外温度控制装置和围岩地温控制装置构成;测试系统由高灵敏度的温度测试元件、风速测试元件以及数据采集仪构成;列车模型以CHR 380A高速列车为模型蓝本,主体材料采用有机玻璃,原型与模型几何相似比为50∶1。试验结果表明：采用控制变量法,洞外气温每降低5 ℃,洞内气温负温长度平均增加104 m;围岩地温每升高5 ℃,洞内气温负温长度平均减少145 m;列车运行间隔短于15 min的寒区隧道,在防冻保温设计时应考虑列车运行间隔对保温设防长度的影响。     

地热源热泵地下埋管换热器传热模型的综述

介绍了地源热泵地下换热器模型发展的过程和现状, 并给出了几种典型的模型形式。     

Techno-economic analysis of an integrated collector storage solar water heater with CPC reflector for households

Few countries bank on solar water heating systems (SWHS) to meet their domestic hot water needs, and instead prefer to use fuel or electric/gas geysers. The reason is the former having relatively high initial investment and performance marred by poor maintenance, and the latter having low initial cost. In this light, we need to compare the economic feasibility of an SWHS with the other alternatives. In almost all solar energy systems, the annual loads are met by a combination of solar and non-solar alternatives, i.e. auxiliary or conventional energy source. Several economic criteria have been proposed and used for evaluating and optimising solar energy systems. The authors have made use of EES software to obtain the economic figures of merit. The proposed model has low initial cost and better long-time thermal performance estimates. The annual solar fraction for the model is 0.55 and the payback period is two years.     

Double skin façades for warm climate regions: Analysis of a solution with an integrated movable shading system

The analysis of a glass double skin façade equipped with integrated movable shading devices is presented, employing three different modelling levels: optics of materials, fluid dynamics of the double skin façade and building energy balance; the aim is to optimize both winter and summer energy performance. The model is developed for a façade oriented towards the south and taking into account the climatic data of central Italy; the solar radiation path with its multiple reflections at the different interfaces have been taken into account employing a ray tracing method. Simulations have been validated by the comparison with data of a similar experimental apparatus and they show that the winter configuration of the proposed façade allows a satisfactory solar heat gain in spite of the presence of shading systems. In summer, the solar heat is mainly absorbed by the external part, and even if a natural convection occurs, there is no significant influence on the inner skin and on the internal environment, thus reducing building cooling requirements. The façade performance was compared with traditional enclosures such as glazed and opaque walls in an office room in central Italy, showing that in the entire year the façade proposed significantly improves the building energy behavior, especially compared to opaque walls and when the configuration with air recovery is considered.