OPTIMAL OPERATION OF MULTIQUALITY WATER SUPPLY SYSTEMS-III: THE Q-C-H MODEL

A new technique for optimal operation of multiquality water supply systems is proposed. The technique, which is known as a Q-C-H (flow-quality-head) model, combines previously developed Sow-quality (Q-C) and flow-head (Q-H) models for optimal operation of water supply systems. The decision variables in the model are the operation of treatment plants, pumps and valves. The model minimizes the cost of water at sources, treatment, energy, and loss of agricultural yield when water quality is low. The model uses an iterative modified projected gradient method combined with the Complex method. As in the Q-C and Q-H models, the solution method is based on decomposition, dis-aggregation/aggregation approach, involving internal and external optimization. The decision variables of the external model are the flows in the loops of the network and the removal ratios at the treatment plants. The operation of the pumps and valves are the decision variables of the internal model. The method is demonstrated by application to an example problem.     

An adaptive heuristic cross-entropy algorithm for optimal design of water distribution systems

The optimal design problem of a water distribution system is to find the water distribution system component characteristics (e.g. pipe diameters, pump heads and maximum power, reservoir storage volumes, etc.) which minimize the system's capital and operational costs such that the system hydraulic laws are maintained (i.e. Kirchhoff's first and second laws), and constraints on quantities and pressures at the consumer nodes are fulfilled. In this study, an adaptive stochastic algorithm for water distribution systems optimal design based on the heuristic cross-entropy method for combinatorial optimization is presented. The algorithm is demonstrated using two well-known benchmark examples from the water distribution systems research literature for single loading gravitational systems, and an example of multiple loadings, pumping, and storage. The results show the cross-entropy dominance over previously published methods.     

A systems-integration approach to the optimization of macroscopic water desalination and distribution networks: a general framework applied to Qatar’s water resources

The objective of this article is to introduce an optimization-based approach for the integrated design and operation of macroscopic water networks. A structural representation approach is developed to embed all potential configurations of interest. This representation accounts for water resources, desalination plants, water users, wastewater treatment facilities, and storage. Water recycle/reuse is enhanced via the use of treated water. Water utilization is improved by minimizing the losses of discharged water resulting from the linkage of power plants and thermal desalination plants and the lack of integration between water production and consumption. Excess water is saved in storage systems or injected in aquifers for strategic (long-term) storage. The developed approach also accounts for the economic values of water uses and storage and for the cost of water production and allocation. An optimization formulation is developed and solved to determine the optimal operation of the infrastructure. The solution also determines the optimal monthly allocation and storage of water resources. A case study is solved for managing the water resources in the State of Qatar while accounting for desalination, distribution, and storage. The solution indicates that storage in tanks reaches its maximum capacity in less than a month while storage in aquifers continues throughout the year as a strategic step towards water security. The solution also illustrates the need to treat wastewater in addition to using desalination of seawater. The output water streams with different qualities are assigned to proper destinations.     

OPTIMAL OPERATION OF MULTI-QUALITY WATER SUPPLY SYSTEMS-II: THE Q-H MODEL

This paper describes the second in a series of three models for optimal operation of multi-quality water supply systems. This second model, which is termed the Q-H (flow-head) model, seeks to determine the optimal operation of pumps and valves, and does not consider water quality aspects. However, the model belongs to the group of three models Tor multi-quality systems because it is one of the two building blocks (the other is the flow-quality Q-C) of a full-llow-quality-head (Q-C-H) model. This Q-H model is based on continuous representations of the head-flow and power-flow functions of the pumping stations, which in turn results in a continuous non-convex optimization model. For a given flow distribution in the network, Q₀, the Q₀-H model is solved for the optimal operation of pumps and valves. The flow distribution is then modified by changing the circular flows, using a projected gradient method combined with the Complex Method which employs the results of the Q₀-H solution, such that the locally optimal solution at the next point has a better value of the objective function. The process is continued until one of the termination criteria is satisfied. The circular flows thus serve as decision variables in an external problem, while in the internal problem the decisions are the operation of pumps and valves. The method is demonstrated by application to a sample problem.     

Designing a model for service facility protection with a time horizon based on tri-level programming

ABSTRACT

This study investigates the tri-level location problem of defence facilities with a time horizon. This research focuses on the r-interdiction median model over a finite time horizon. This research aims to protect the service facilities using the defence facilities against the most severe attack scenario of the attacker, so that the system is able to use its maximum power to serve the customers after being damaged. This problem is established on the basis of leader–follower games in the form of defender–attacker–defender. Moreover, attempts are made to make the model more realistic by considering a time horizon. To solve the problem, a combination of a genetic algorithm, simulated annealing and an exact method is used. Comparison of the solution method of the applied metaheuristic algorithm and the exact solution method in a number of small samples indicates the desirable performance of this algorithm in a reasonable time.     

Long term biological developments in water Cherenkov detector media

Fourteen years ago, studies on bacteria growing in clean water were made in order to assess the hazard imposed by a possible expansion of bacteria population in the water tanks of the Pierre Auger Observatory Cherenkov detectors. In 1999 TANGO Array, a reduced-size unitary cell, composed of four water Cherenkov detectors, was constructed at the TANDAR campus of the Atomic Energy Commission, in Buenos Aires, to be used as a working model of the proposed surface array. TANGO Array ran for one year observing energy, intensity, and arrival directions of cosmic rays at sea level. Nine years after it was decommissioned, the water tanks configuring the Cherenkov detectors are still kept closed. In May 2009 water and liner samples from these tanks were collected to determine eventual long term bacteria growth in the internal detector environment, which is very similar to those of the detectors installed in the Malargüe Site.In the present note we report the results of the bacteriological study performed on the samples obtained from the TANGO Array detector tanks. Cultivable, long time surviving, bacterial species were identified, both in the water mass and on the liner surface, and the light transmission in water at the relevant Cherenkov wavelength was studied. An upper limit of possible interferences caused by bacteria is estimated.     

大容量水泥储仓群水压爆破拆除

位于贵阳市区的贵阳水泥厂有由４个大型筒仓两两相切组成的大容量水泥储仓群（７４０８．４ｍ３）需拆除，单个筒仓内径１０ｍ、高２９．５ｍ。采用水压爆破技术拆除，设计采用多药包布置形式，分５层、每层布６个分药包，并假设分药包为“中心药包”进行药量计算。施爆时注水约５０００ｔ，水压爆破用药量２８７．４ｋｇ，爆破后爆堆高度仅为３ｍ，近１０ｍ的未注水部位的钢筋混凝土也已破碎。爆破安全、高效、拆除过程无灰尘，爆破效果很好，为同类工程提供了可借鉴的经验。     

Optimal long-term design,rehabilitation and upgrading of water distribution networks

Given a limited budget, the choice of the best water distribution network upgrading strategy is a complex optimization problem. A model for the optimal long-term design and upgrading of new and existing water distribution networks is presented. A key strength of the methodology is the use of maximum entropy flows, which reduces the size of the problem and enables the application of linear programming for pipe size optimization. It also ensures the reliability level is high. The capital and maintenance costs and hydraulic performance are considered simultaneously for a predefined design horizon. The timing of upgrading over the entire planning horizon is obtained by dynamic programming. The deterioration over time of the structural integrity and hydraulic capacity of every pipe are explicitly considered. The upgrading options considered include pipe paralleling and replacement. The effectiveness of the model is demonstrated using the water supply network of Wobulenzi town in Uganda.     

Quick management of accidental tritium exposure cases

Removal half-life (RHL) of tritium is one of the best means for optimising medical treatment, reduction of committed effective dose (CED) and quick/easy handling of a large group of workers for medical treatment reference. The removal of tritium from the body depends on age, temperature, relative humidity and daily rainfall; so tritium removal rate, its follow-up and proper data analysis and recording are the best techniques for management of accidental acute tritium exposed cases. The decision of referring for medical treatment or medical intervention (MI) would be based on workers' tritium RHL history taken from their bodies at the facilities. The workers with tritium intake up to 1 ALI shall not be considered for medical treatment as it is a derived limit of annual total effective dose. The short-term MI may be considered for tritium intake of 1-10 ALI; however, if the results show intake ≥100 ALI, extended strong medical/therapeutic intervention may be recommended based on the severity of exposure for maximum CED reduction requirements and annual total effective dose limit. The methodology is very useful for pressurized heavy water reactors (PHWRs) which are mainly operated by Canada and India and future fusion reactor technologies. Proper management will optimise the cases for medical treatment and enhance public acceptance of nuclear fission and fusion reactor technologies.     

禹门口扩建泵站岩坎爆破拆除与安全控制

针对禹门口黄河提水工程中扩建泵站预留岩坎爆破拆除难度较大的情况,采用深孔爆破和预裂爆破相结合、高精度塑料导爆管雷管延时起爆的爆破技术,钻孔分角度布孔,岩坎分区单耗,爆破总药量3 633kg,总方量3 500m~3;综合炸药单耗1.04kg/m~3,控制最大单响药量24kg。岩坎爆破从中部开口起爆,地表传爆雷管孔间、排间延时为17、25、65ms,保证每个炮孔按照延时起爆不重段,实现了精准爆破。采取严格周密的安全防护措施和振动监测,爆破过程中未见飞石和涌浪,各建筑物实测振速均小于安全标准,保障了一级泵站、扩建泵站、周围交通设施的安全。岩坎爆破拆除取得成功,爆破效应得以有效控制,设计参数和控制标准可供类似工程参考。     

The ‘meaning’ behind household rainwater use: An Australian case study

Suburban rainwater tanks have the potential to reduce household mains water consumption, but simply installing the technology does not mean rainwater is automatically incorporated into everyday practices. Exploring how rainwater is conceptualised in contrast to mains water, and the way it is used in household practices, provides insights into why rainwater tank households may not be using less mains water than households without tanks. Water saving strategies that promote rainwater tanks tend to focus on installation rather than how, why and where rainwater is substituted for mains water. While there is the assumption that rainwater tank households use less mains water, an investigation of rainwater practices have revealed influential social and cultural factors that extend far beyond installing a new technology. Drawing on a household water study involving 21 interviews and 1425 surveys in the Illawarra region, Australia, practice theory principles provided insight into how rainwater was conceptualised, revealing the ‘meaning’ of rainwater as an influential factor informing its everyday use. The historical, cultural and emotional meanings of rainwater contribute to shaping its use in everyday practices. Rainwater means different things to different people and it is this spectrum of meanings that inform the range of practices, and volumes of use. This study highlights opportunities for increased integration of rainwater into household practices, which may broaden the perceived uses and usefulness, reshaping it's meaning over time.     

真空冷却过程中气体温度变化特性的研究

为了研究真空冷却过程中真空室内气体温度的变化特性，以水为实验对象，在真空室内布置了压力及多个温度测点，进行多组真空冷却实验，从而测得在抽真空和复压过程中真空室内的压力和各点的气体温度值。研究表明，当真空室内压力发生变化时，真空室内气体温度的变化具有某些特征，并且气体温度还受容器壁温、水温等的影响，本文针对这些特征进行了相关实验及理论分析，并得到了相似的变化规律。     

Operational planning models for distribution networks

The design and optimisation of a logistic network deals with a wide set of decisions, e.g. the determination of the best location and capacity of the different logistic facilities (production plants, distribution centres, transit points, wholesalers, etc.), the allocation of the product demand coming from customers in presence (or absence) of fractionable flows of material, the determination of the best transportation mode (truck, rail, etc.) as well as loading and routing of vehicles. These decisions involve multiple stages of a distribution network: customers-regional distribution centres (RDC), RDCs-central distribution centres (CDC) and CDCs-production plants and sources, in presence of multiple products and the variable time (i.e. time-dependent product demand and flows of material). This paper presents a top-down methodology that joins the strategic planning, the tactical planning and the operational planning of distribution networks with a special focus on the development of effective heuristic methods to face the vehicle routing problem. Original models and heuristic algorithms for the operational planning are illustrated. The impact of the strategic and tactical decisions on the performance of the operational planning is evaluated by the application of the proposed hierarchical approach to two realistic case studies. Obtained results are illustrated in a what-if experimental analysis conducted on multiple problem settings and realistic scenarios.     

Macro-instability: a chaotic flow component in stirred tanks

Chaotic features of the macro-instability (MI) of flow patterns in stirred tanks are studied in this paper. Datasets obtained by measuring the axial component of the fluid velocity and the tangential force affecting the baffles are used. Two geometrically identical, flat-bottomed cylindrical mixing tanks (diameter of 0.3m) stirred with either pitched blade turbine impellers or Rushton turbine impeller are used in the experiments, and water and aqueous glycerol solutions are used as the working liquids. First, the presence of the MI component in the data is examined by spectral analysis. Then, the MI components are identified in the data using the proper orthogonal decomposition (POD) technique. The attractors of the macro-instability are reconstructed using either the POD eigenmodes or a method of delays and finally the attractor invariants are evaluated. The dependence of the correlation dimension and maximum Lyapunov exponent on the vessel operational conditions is determined together with their distribution within the tank. No significant spatial variability of the correlation dimension value is observed. Its value is strongly influenced by impeller speed and by the vessel-impeller geometry. More profound spatial distribution is displayed by the maximum Lyapunov exponent taking distinctly positive values. These two invariants, therefore, can be used to locate distinctive regions with qualitatively different MI dynamics within the stirred tank.     

Extension of the hybrid linear programming method to optimize simultaneously the design and operation of groundwater utilization systems

This article proposes a hybrid linear programming (LP-LP) methodology for the simultaneous optimal design and operation of groundwater utilization systems. The proposed model is an extension of an earlier LP-LP model proposed by the authors for the optimal operation of a set of existing wells. The proposed model can be used to optimally determine the number, configuration and pumping rates of the operational wells out of potential wells with fixed locations to minimize the total cost of utilizing a two-dimensional confined aquifer under steady-state flow conditions. The model is able to take into account the well installation, piping and pump installation costs in addition to the operational costs, including the cost of energy and maintenance. The solution to the problem is defined by well locations and their pumping rates, minimizing the total cost while satisfying a downstream demand, lower/upper bound on the pumping rates, and lower/upper bound on the water level drawdown at the wells. A discretized version of the differential equation governing the flow is first embedded into the model formulation as a set of additional constraints. The resulting mixed-integer highly constrained nonlinear optimization problem is then decomposed into two subproblems with different sets of decision variables, one with a piezometric head and the other with the operational well locations and the corresponding pumping rates. The binary variables representing the well locations are approximated by a continuous variable leading to two LP subproblems. Having started with a random value for all decision variables, the two subproblems are solved iteratively until convergence is achieved. The performance and ability of the proposed method are tested against a hypothetical problem from the literature and the results are presented and compared with those obtained using a mixed-integer nonlinear programming method. The results show the efficiency and effectiveness of the proposed method for solving practical groundwater management problems.     

Chlorination byproducts, their toxicodynamics and removal from drinking water

No doubt that chlorination has been successfully used for the control of water borne infections diseases for more than a century. However identification of chlorination byproducts (CBPs) and incidences of potential health hazards created a major issue on the balancing of the toxicodynamics of the chemical species and risk from pathogenic microbes in the supply of drinking water. There have been epidemiological evidences of close relationship between its exposure and adverse outcomes particularly the cancers of vital organs in human beings. Halogenated trihalomethanes (THMs) and haloacetic acids (HAAs) are two major classes of disinfection byproducts (DBPs) commonly found in waters disinfected with chlorine. The total concentration of trihalomethanes and the formation of individual THM species in chlorinated water strongly depend on the composition of the raw water, on operational parameters and on the occurrence of residual chlorine in the distribution system. Attempts have been made to develop predictive models to establish the production and kinetics of THM formations. These models may be useful for operational purposes during water treatment and water quality management. It is also suggested to explore some biomarkers for determination of DBP production. Various methods have been suggested which include adsorption on activated carbons, coagulation with polymer, alum, lime or iron, sulfates, ion exchange and membrane process for the removal of DBPs. Thus in order to reduce the public health risk from these toxic compounds regulation must be inforced for the implementation of guideline values to lower the allowable concentrations or exposure.     

Riverbank filtration for sustainable water supply: application to a large-scale facility on the Nile River

Riverbank filtration (RBF) is an efficient and low-cost natural alternative technology for water supply application in which surface water contaminants are removed or degraded as the infiltrating water moves from the river/lake to the pumping wells. The removal or degradation of contaminants is a combination of physicochemical and biological processes. For more than 100 years, RBF has been used in Europe for public and industrial water supply along Rhine, Elbe, and Danube rivers. This paper presents an investigation of a full-scale RBF plant located in Upper Egypt as section of Nile valley to produce drinking water. The studied plant is constructed in 2004 to supply potable water for Sidfa city (30,000 residents), Assiut Governorate. It consists of 6 vertical wells, each about 60 m deep, with distance about 30 m from the west bank of Nile. Water samples from Nile as induced surface water, from background groundwater, and from production wellfield were collected and analyzed at three discrete events. Quality measurements of physical, chemical, and microbiological characteristics were obtained. Comparison of produced water with surface and background natural groundwater for the investigated plant has proven the effectiveness of RBF technique for potable water supply in Upper Egypt. Physicochemical and microbiological characteristics of the produced water are better than the allowable standards for drinking purposes. The results prove the implementation of RBF treatment method for water supply in Nile valley.     

Optimal and Heuristic Facility Phase-out Strategies

This paper presents an efficient branch and bound algorithm and near optimal heuristic algorithms for solving the problem of withdrawing inventory and/or service facilities for a good or service whose overall demand is declining over time. In particular, this paper models the problem faced by a manager who must consider closing up to M initially open and operating support facilities as demand shifts and declines over a T period planning horizon. The criterion is minimization of total estimated discounted costs. The costs considered are the variable operating cost at each facility, the transportation costs between facilities and demand centers, and the costs to operate and close each facility. Computational results are presented for both the optimum finding and heuristic algorithms.     

Ice-water two-phase flow behavior in ice heat storage systems

In this paper, we describe (1) the characteristics of ice-water two-phase flow created in a supercooling-type ice storage system, (2) the numerical analysis models for both processes of ice storing and melting within ice storage tanks, and (3) the design technologies for ice storage systems based on such predictive models, as well as the operational performance of actual equipment built with these design technologies. As the result of this technological development, it has been confirmed that the predictive approaches for the one dimensional ice accumulation in the given tanks and ice melting with low temperature water enough to air conditioning applications are reasonable and widely usable. Furthermore by the design conditions obtained here it is possible to simplify the construction of ice storage tanks and to realize high reliability in the actual equipment.     

Dynamic-demand capacitated facility location problems with and without relocation

We consider two multi-period dynamic-demand capacitated location problems. In the first problem, the facilities are allowed to be relocated in each period, whereas in the second they are kept at a fixed location determined at the beginning of the planning horizon. We provide Lagrangian Relaxation and Benders Decomposition algorithms, including an ?-optimal BD algorithm, for the solution for the first model and a Benders Decomposition algorithm for the second. For detailed analysis, we generate a wide variety of instances to test the performance of the algorithms by taking into account varying number of customer locations and time periods in the planning horizon as well as fixed cost structures and facility capacities. We observe that the efficiency of the solution algorithms depends on the input data structure, specifically the cost structures, the facility capacities (which, in turn, dictate the expected number of open facilities), and the variation in the total customer demand from period to period.