scholarly journals A Dynamic Optimization Strategy for the Operation of Large Scale Seawater Reverses Osmosis System

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Aipeng Jiang ◽  
Jian Wang ◽  
Wen Cheng ◽  
Changxin Xing ◽  
Shu Jiangzhou
Keyword(s):  
Finite Element ◽  
Dynamic Model ◽  
Large Scale ◽  
Optimal Solution ◽  
Differential Algebraic Equations ◽  
Optimal Operation ◽  
Algebraic Equations ◽  
Optimization Strategy ◽  
Storage Tanks

In this work, an efficient strategy was proposed for efficient solution of the dynamic model of SWRO system. Since the dynamic model is formulated by a set of differential-algebraic equations, simultaneous strategies based on collocations on finite element were used to transform the DAOP into large scale nonlinear programming problem named Opt2. Then, simulation of RO process and storage tanks was carried element by element and step by step with fixed control variables. All the obtained values of these variables then were used as the initial value for the optimal solution of SWRO system. Finally, in order to accelerate the computing efficiency and at the same time to keep enough accuracy for the solution of Opt2, a simple but efficient finite element refinement rule was used to reduce the scale of Opt2. The proposed strategy was applied to a large scale SWRO system with 8 RO plants and 4 storage tanks as case study. Computing result shows that the proposed strategy is quite effective for optimal operation of the large scale SWRO system; the optimal problem can be successfully solved within decades of iterations and several minutes when load and other operating parameters fluctuate.

scholarly journals Approximation of potential-driven flow dynamics in large-scale self-similar tree networks

2011 ◽  
Vol 467 (2134) ◽  
pp. 2810-2824 ◽  
Author(s):  
Jason Mayes ◽  
Mihir Sen
Keyword(s):  
Mathematical Model ◽  
Analytical Solutions ◽  
Large Scale ◽  
Differential Algebraic Equations ◽  
Flow Dynamics ◽  
Algebraic Equations ◽  
Tree Networks ◽  
Self Similar ◽  
Large Scale Flow ◽  
The Mathematical Model

Dynamic analysis of large-scale flow networks is made difficult by the large system of differential-algebraic equations resulting from its modelling. To simplify analysis, the mathematical model must be sufficiently reduced in complexity. For self-similar tree networks, this reduction can be made using the network’s structure in way that can allow simple, analytical solutions. For very large, but finite, networks, analytical solutions are more difficult to obtain. In the infinite limit, however, analysis is sometimes greatly simplified. It is shown that approximating large finite networks as infinite not only simplifies the analysis, but also provides an excellent approximate solution.

scholarly journals Water demand forecasting for the optimal operation of large-scale drinking water networks: The Barcelona Case Study.

2014 ◽  
Vol 47 (3) ◽  
pp. 10457-10462 ◽  
Author(s):  
Ajay Kumar Sampathirao ◽  
Juan Manuel Grosso ◽  
Pantelis Sopasakis ◽  
Carlos Ocampo-Martinez ◽  
Alberto Bemporad ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Demand ◽  
Large Scale ◽  
Demand Forecasting ◽  
Optimal Operation ◽  
Water Networks ◽  
Water Demand Forecasting

Optimal Power Generation Unit Sizing for Combined Heating and Power Systems With Uncertain Loads and Fuel/Electricity Prices

2011 ◽  
Author(s):  
Aaron Smith ◽  
Kyungtae Yun ◽  
Robert Thomas ◽  
Rogelio Luck
Keyword(s):  
Power Systems ◽  
Optimal Solution ◽  
Optimal Operation ◽  
Computational Effort ◽  
Mixed Integer ◽  
Weather Data ◽  
Optimal Sizing ◽  
Electricity Cost ◽  
Analytical Scheme

An optimal sizing method is developed in this work based on an analytical scheme for determining optimal operation decisions. Using the analytic optimal operation scheme allows for a more thorough optimal sizing method because of the minimal computational effort required as compared to mixed integer programming approaches. For example, an optimal sizing method based on this approach can more feasibly consider several years of weather data and the range of likely fuel/electricity costs for the term of operation of the PGU. The optimal sizing method in this work takes advantage of this efficient optimal operation scheme and provides a robust optimal solution with respect to weather and fuel/electricity cost uncertainty. A case study of a medium sized office building is carried out by testing the algorithm for a range of 20 commercially available diesel engine PGUs.

Dynamic Modeling and Grasp Characteristics Analysis of an Underactuated Prosthetic Finger

2014 ◽  
Vol 513-517 ◽  
pp. 3446-3452 ◽  
Author(s):  
Li Chu ◽  
Yi Zhang ◽  
Hua Deng
Keyword(s):  
Dynamic Model ◽  
Differential Algebraic Equations ◽  
Algebraic Equations ◽  
Constraint Force ◽  
Characteristic Index ◽  
Grasp Stability ◽  
Adaptive Capability ◽  
Prosthetic Finger ◽  
Underactuated Finger ◽  
Self Adaptive

A dynamic model was established using the virtual spring approach for the underactuated prosthetic finger containing the closed kinematic chains and holonomic constraints. The dynamic model was verified by grasp simulation. The virtual spring is used to approximate the constraint force and differential algebraic equations are converted into ordinary differential equations which are ideal for simulation and real-time control. The grasp characteristics of the underactuated finger were studied based on the model with the stiffness of the linear springs as variables. By properly increasing the stiffness of springs, the grasp stability of underactuated finger could be improved and ejection phenomenon would be reduced. However, self-adaptive capability would be reduced with large stiffness. A characteristic index was used for estimating grasp stability and self-adaptive capability. The simulation results show that setting the stiffness of the linear springs between 1N/mm and 2N/mm is the best choice for the underactuated finger.

scholarly journals Solving Weighted Constraint Satisfaction Problems with Memetic/Exact Hybrid Algorithms

2009 ◽  
Vol 35 ◽  
pp. 533-555 ◽  
Author(s):  
J. E. Gallardo ◽  
C. Cotta ◽  
A. J. Fernández
Keyword(s):  
Constraint Satisfaction ◽  
Large Scale ◽  
Constraint Satisfaction Problem ◽  
Heuristic Method ◽  
Optimal Solution ◽  
Constraint Satisfaction Problems ◽  
Still Life ◽  
Level Model ◽  
Weighted Constraint

A weighted constraint satisfaction problem (WCSP) is a constraint satisfaction problem in which preferences among solutions can be expressed. Bucket elimination is a complete technique commonly used to solve this kind of constraint satisfaction problem. When the memory required to apply bucket elimination is too high, a heuristic method based on it (denominated mini-buckets) can be used to calculate bounds for the optimal solution. Nevertheless, the curse of dimensionality makes these techniques impractical on large scale problems. In response to this situation, we present a memetic algorithm for WCSPs in which bucket elimination is used as a mechanism for recombining solutions, providing the best possible child from the parental set. Subsequently, a multi-level model in which this exact/metaheuristic hybrid is further hybridized with branch-and-bound techniques and mini-buckets is studied. As a case study, we have applied these algorithms to the resolution of the maximum density still life problem, a hard constraint optimization problem based on Conway's game of life. The resulting algorithm consistently finds optimal patterns for up to date solved instances in less time than current approaches. Moreover, it is shown that this proposal provides new best known solutions for very large instances.

scholarly journals A graph-theoretic approach to sparse matrix inversion for implicit differential algebraic equations

2013 ◽  
Vol 4 (1) ◽  
pp. 243-250
Author(s):  
H. Yoshimura
Keyword(s):  
Bipartite Graph ◽  
Large Scale ◽  
Jacobian Matrix ◽  
Sparse Matrix ◽  
Mechanical Systems ◽  
Differential Algebraic Equations ◽  
Matrix Inversion ◽  
Theoretic Approach ◽  
Algebraic Equations ◽  
Input Output

Abstract. In this paper, we propose an efficient numerical scheme to compute sparse matrix inversions for Implicit Differential Algebraic Equations of large-scale nonlinear mechanical systems. We first formulate mechanical systems with constraints by Dirac structures and associated Lagrangian systems. Second, we show how to allocate input-output relations to the variables in kinematical and dynamical relations appearing in DAEs by introducing an oriented bipartite graph. Then, we also show that the matrix inversion of Jacobian matrix associated to the kinematical and dynamical relations can be carried out by using the input-output relations and we explain solvability of the sparse Jacobian matrix inversion by using the bipartite graph. Finally, we propose an efficient symbolic generation algorithm to compute the sparse matrix inversion of the Jacobian matrix, and we demonstrate the validity in numerical efficiency by an example of the stanford manipulator.

scholarly journals Dynamic Modelling and Identification of a Waterjet Cutting System

2003 ◽  
Author(s):  
Brian C. Fabien ◽  
M. Ramulu
Keyword(s):  
Dynamic Model ◽  
High Pressures ◽  
Dynamic Modelling ◽  
Check Valve ◽  
Differential Algebraic Equations ◽  
Algebraic Equations ◽  
Unknown Parameters ◽  
Actual System ◽  
Waterjet Cutting ◽  
Cutting System

This paper describes a new dynamic model for a waterjet cutting system that includes a double-acting reciprocating intensifier pump. Since the system operates at high pressures the fluid flow is assumed to be compressible. The dynamic model includes the characteristics of the intensifier pump, the check valves, the accumulator, the system piping and compressible jet flow through the nozzle. The system model is presented as a set of differential-algebraic equations. Experimental results for an actual system are used to identify the discharge coefficient of the nozzle, certain unknown parameters associated with the check valve, and to determine the velocity profile of the piston in the intensifier pump. The identification is accomplished by formulating and solving a parameter optimization problem. The paper also includes numerical simulation results that validate the dynamic model.

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