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  • Articles  (13)
  • optimization  (13)
  • 2010-2014
  • 1990-1994  (9)
  • 1985-1989  (4)
  • 1950-1954
  • Architecture, Civil Engineering, Surveying  (13)
  • 1
    Electronic Resource
    Electronic Resource
    Entropy principles in the prediction of water quality values at discontinued monitoring stations (1994)
    Springer
    Stochastic environmental research and risk assessment 8 (1994), S. 301-317 
    Details
    ISSN: 1436-3259
    Keywords: Change ; discontinued stations ; entropy ; networks ; optimization ; prediction ; unbiased ; water quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract A new methodology for predicting water quality values at discontinued water quality monitoring stations is proposed. The method is based upon the Principle of Maximum Entropy (POME) and provides unbiased predictions of water quality levels at upstream tributaries and on the mainstem of a river given observed changes in the distribution of the same water quality parameter at a downstream location. Changes in the values of water quality parameters which are known a priori to have occurred upstream, but which are not sufficiently large to account for all the observed change in the same water quality parameter at the downstream location are able to be incorporated in the method through the introduction of a new term in the basic entropy expression. Application of the procedure to water quality monitoring on the Mackenzie River in Queensland, Australia indicates the method has considerable potential for prediction of water quality at discontinued stations. The method also has potential for identifying the location of causes of observed changes in water quality at a downstream station.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01588759
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  • 2
    Electronic Resource
    Electronic Resource
    A sensitivity analysis and parametric study for the evaluation of the optimal management of a contaminated aquifer (1994)
    Springer
    Water resources management 8 (1994), S. 11-31 
    Details
    ISSN: 1573-1650
    Keywords: Aquifer contamination ; groundwater quality management ; sensitivity analysis ; parametric study ; optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract A typical groundwater remedation problem is studied by using a combined simulation-optimization model. The management procedure employs groundwater flow and contaminant transport simulation models in conjunction with linear and quadratic programming techniques. The methodology is applied to the hydrodynamic control of a contaminant plume that has to be stabilized and removed by a system of pumping wells. The paper focuses mainly upon a sensitivity analysis to the aquifer transmissivity. The effect of changes in the transmissivities of a zoned aquifer upon the optimal solutions of the management problem is examined by considering the optimal pumping rates, the time to remediation and the pumped groundwater volume as the key output variables of the remediation strategies. In addition, the influence of the dispersivities and the imposed hydraulic gradient upon the same output variables is critically evaluated. The results of the study illustrate the need for uncertainty reduction in the knowledge of the hydrogeologic parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00872277
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  • 3
    Electronic Resource
    Electronic Resource
    Optimal allocation of surface water in regional water management (1994)
    Springer
    Water resources management 8 (1994), S. 137-153 
    Details
    ISSN: 1573-1650
    Keywords: Regional water management ; surface water ; surface water supply capacity ; optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract Surface water is a scarce reource that is applied by various users for a variety of activities. The regulation of surface water use is an element of regional water management at various management levels. At each management level, the allocation of surface water supply capacity is a policy instrument. An optimization model has been formulated to support the evaluation of potential allocations at a particular management level. The model describes the allocation problem as a network, in which arcs represent waterways and nodes represent inlets and locations where there is a demand for surface water supply. The use of surface water for a specific activity at a specific node is referred to as an application, for example, for sprinkling, for use as cooling water, for dissolving effluent, and for conservation of environmental areas. The optimization model generates the optimal allocation of surface water and of surface water supply capacity. The operation of the model was demonstrated by a case study, where it was applied to maximize the expected revenues in agriculture (measured as value added).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00872433
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  • 4
    Electronic Resource
    Electronic Resource
    Optimal flood control in multireservoir cascade systems with deterministic inflow forecasts (1993)
    Springer
    Water resources management 7 (1993), S. 207-223 
    Details
    ISSN: 1573-1650
    Keywords: Flood control ; multireservoir systems ; optimization ; aggregation and disaggregation ; coordinated operation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract This article presents the formal analysis of a problem of the optimal flood control in systems of serially connected multiple water reservoirs. It is assumed, that the basic goal is minimization of the peak flow measured at a point (cross-section) located downstream from all reservoirs and that inflows to the system are deterministic. A theorem expressing sufficient conditions of optimality for combinations of releases from the reservoirs is presented together with the relevant proof. The main features of the optimal combinations of controls are thoroughly explained. Afterwards, two methods of determining the optimal releases are presented. Finally, the results of the application of the proposed methodology to a small, four reservoir system are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01675304
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  • 5
    Electronic Resource
    Electronic Resource
    Multiple-objective stochastic waste-load allocation (1992)
    Springer
    Water resources management 6 (1992), S. 117-133 
    Details
    ISSN: 1573-1650
    Keywords: Waste-load allocation ; water-quality management ; multiple-objective analysis ; optimization ; uncertainty analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract The practice of waste-load allocation in water quality management involves several noncommensurate and conflicting objectives. In particular, the objectives considered in this multiobjective stochastic waste-load allocation study are (1) maximization of total waste discharge, (2) maximization of instream dissolved oxygen concentration, (3) minimization of difference in equity measures, and (4) maximization of reliability of water quality compliance. To demonstrate the analysis, the model was applied to an example involving six waste dischargers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00872207
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  • 6
    Electronic Resource
    Electronic Resource
    Selecting risk levels in chance-constrained reservoir operation modeling: A fuzzy set approach (1991)
    Springer
    Water resources management 4 (1991), S. 251-271 
    Details
    ISSN: 1573-1650
    Keywords: Reservoir operation ; treatment of imprecision ; optimization ; satisficing ; fuzzy sets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract Many modifications, extensions, discussions, and evaluations of chance-constrained reservoir operating models have been reported in the technical literature. Lack of economic data and the fact that the establishment of acceptable risk levels in these types of models involves a human factor with all its vagueness of perception, subjectivity, and attitudes may not permit proper application of either reliability or multiobjective programming approaches. This paper presents a unique methodology for handling a practical problem of selecting risk levels in chance-constrained reservoir operation modeling. The proposed methodology is based on fuzzy set theory. Two types of fuzzy sets are used in the formulation of the reservoir long-term planning model, one for constraints and one for the objective function. An iterative solution algorithm for deriving an optimal decision using fuzzy set operations and the chance-constrained approach is developed and presented. A practical application of the approach demonstrates the feasibility and efficiency of both the proposed approach and its iterative search procedure for selecting risk levels in chance-constrained reservoir modeling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00430340
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  • 7
    Electronic Resource
    Electronic Resource
    Rehabilitation and replacement of water distribution system components considering uncertainties (1990)
    Springer
    Stochastic environmental research and risk assessment 4 (1990), S. 277-294 
    Details
    ISSN: 1436-3259
    Keywords: Water distribution ; optimization ; nonlinear programming ; integer programming ; chance constraints ; rehabilation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract This paper presents the mathematical development of an integer — nonlinear programming chance — constrained optimization model for the minimum cost rehabilitation/replacement of water distribution system components. Particular attention is given to the handling of uncertainties in the roughness factors and the loading conditions including both the random demand and preassure head requirements. The advantages of the proposed model include the ability to: 1) handle the optimal timing of rehabilitation/replacement for water distribution system components; 2) link a mixed-integer linear program solver, a nonlinear program solver, and a hydraulic simulator into an optimization framework; 3) handle the uncertainties of some of the variables; 4) incorporate various kinds of cost functions; and 5) handle multiple loading conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01544082
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  • 8
    Electronic Resource
    Electronic Resource
    Model for real-time optimal flood control operation of a reservoir system (1990)
    Springer
    Water resources management 4 (1990), S. 21-46 
    Details
    ISSN: 1573-1650
    Keywords: Flood control ; unsteady flow ; reservoir operation ; optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract A methodology and model have been developed for the real-time optimal flood operation of river-reservoir systems. This methodology is based upon combining a nonlinear programming model with a flood-routing simulation model within an optimal control framework. The generalized reduced gradient code GRG2 is used to perform the nonlinear optimization and the simulator is the U.S. National Wheather Service DWOPER code. Application of the model is illustrated through a case study of Lake Travis on the Lower Colorado River in Texas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00429923
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  • 9
    Electronic Resource
    Electronic Resource
    Two-step dynamic programming approach for optimal irrigation water allocation (1990)
    Springer
    Water resources management 4 (1990), S. 187-204 
    Details
    ISSN: 1573-1650
    Keywords: Dynamic programming ; irrigation management ; optimization ; production function ; stochastic model ; water allocation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract A two-step (deterministic and stochastic) dynamic programming approach has been introduced in this study to solve the complex problem of optimal water allocation in a run-of-the-river-type irrigation project. The complexity of a real-world situation is represented by incorporating in the optimization model the stochasticity of water supply and the nonlinearity of crop production functions. A nonlinear, dated, and multiplicative production function is transformed into a sequentially additive type to replace the usual method of creating an additional ‘state of the plant variable’ which only increases the dimension of the problem. As compared to the explicit stochastic dynamic programming which necessitates, along with its use, an enormous computational complexity due to the so-called ‘curse of dimensionality’, the present model can approximate the theoretical global optimum, at least for the present case study, with a dramatic reduction in computer processing time. It also eliminates the rigidity of the policy derived by the explicit approach, since it provides irrigation planners with alternative decision policies which incorporate intangibles and other nonengineering factors. The traditional method of fixing the cropping pattern based on deterministic estimates of a dependable water supply can likewise be evaluated by the use of the present model. The results of the model's application appear to be practically acceptable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00431143
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  • 10
    Electronic Resource
    Electronic Resource
    On the parametric approach to unit hydrograph identification (1989)
    Springer
    Water resources management 3 (1989), S. 107-128 
    Details
    ISSN: 1573-1650
    Keywords: Unit hydrograph ; instantaneous unit hydrograph ; identification ; probability density function ; probability distribution function ; method of moments ; optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract Unit hydrograph identification by the parametric approach is based on the assumption of a proper analytical form for its shape, using a limited number of parameters. This paper presents various suitable analytical forms for the instantaneous unit hydrograph, originated from known probability density functions or transformations of them. Analytical expressions for the moments of area of these form versus their definition parameters are theoretically derived. The relation between moments and specific shape characteristics are also examined. Two different methods of parameter estimation are studied, the first being the well-known method of moments, while the second is based on the minimization of the integral error between derived and recorded flood hydrographs. The above tasks are illustrated with application examples originated from case studies of catchments in Greece.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00872467
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  • 11
    Electronic Resource
    Electronic Resource
    Reservoir operation policies for optimizing energy generation at the Shiroro Dam (1988)
    Springer
    Water resources management 2 (1988), S. 209-219 
    Details
    ISSN: 1573-1650
    Keywords: Hydroelectric power ; operating policy ; optimization ; probabilistic dynamic programming ; Shiroro Dam
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract Reservoir water release policies are computed for the Shiroro Dam hydroelectric power scheme in Northern Nigeria, using a probabilistic dynamic programming model. The state variable is the reservoir storage volume, while the uncertain nature of the inflow process is accounted for in the model by considering different possible inflow volumes and their inflow probabilities. Simulation of the reservoir operations with the derived policies show that on the average the hydrosystem has acceptable reliability when two units are in use, at 45% design power plant factor. At 70% power plant factor, which is the desired optimum for the power system in Nigeria, system failures are frequent and, in most cases, severe. For normal operation of the Shiroro Dam hydroelectric power system, two or three generating units, running at 40–50% power plant factor is recommended.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00429902
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  • 12
    Electronic Resource
    Electronic Resource
    Multi-objective stochastic groundwater management of nonuniform, homogeneous aquifers (1987)
    Springer
    Water resources management 1 (1987), S. 241-254 
    Details
    ISSN: 1573-1650
    Keywords: Groundwater management ; optimization ; uncertainty analysis ; reliability ; multiple-objective analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract Like any other resources planning and management, groundwater management is performed in a stochastic environment in which the system itself involves a number of random elements. Consequences as a result of decisions made based on analyses are not certain. This paper presents a management model using the chance-constrained framework which explicitly considers the random nature of aquifer properties. The model enables the derivation of an optimal groundwater management policy that would satisfy required operation performance reliability. Furthermore, the chance-constrained model is extended to the multi-objective optimization framework in which a tradeoff between total water supply pumpage and system performance reliability is explicitly considered. The models are applied to a hypothetical example of a steady, nonuniform, homogeneous confined aquifer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00421878
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  • 13
    Electronic Resource
    Electronic Resource
    An iterative method to optimize the operation of reservoir systems (1987)
    Springer
    Water resources management 1 (1987), S. 255-266 
    Details
    ISSN: 1573-1650
    Keywords: Reservoir operation ; optimization ; dynamic programming ; water resources planning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract Optimization of long-term operation of real-world reservoir systems by dynamic programming has been studied. Computer time requirements make it necessary to use iterative methods in the case of multi-reservoir systems. State-incremental dynamic programming provides a reasonable rate of convergence for serial systems when initial policies are suitably chosen. A new method is proposed that combines dynamic programming with successive approximations and state-incremental dynamic programming. Incremental sequential dynamic programming is especially useful for systems of complex configuration which cannot be optimized with other iterative methods due to very slow convergence. Choices of initial policy, state increment, and the number of states to be considered in each iteration are investigated in two case studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00421879
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