scholarly journals An Interactive Environment for Supporting the Transition from Simulation to Optimization

2003 ◽  
Vol 11 (4) ◽  
pp. 263-272 ◽  
Author(s):  
Christian H. Bischof ◽  
H. Martin Bücker ◽  
Bruno Lang ◽  
Arno Rasch

Numerical simulation is a powerful tool in science and engineering, and it is also used for optimizing the design of products and experiments rather than only for reproducing the behavior of scientific and engineering systems. In order to reduce the number of simulation runs, the traditional "trial and error" approach for finding near-to-optimum design parameters is more and more replaced with efficient numerical optimization algorithms. Done by hand, the coupling of simulation and optimization software is tedious and error-prone. In this note we introduce a software environment called EFCOSS (Environment For Combining Optimization and Simulation Software) that facilitates and speeds up this task by doing much of the required work automatically. Our framework includes support for automatic differentiation providing the derivatives required by many optimization algorithms. We describe the process of integrating the widely used computational fluid dynamics package FLUENT and a MINPACK-1 least squares optimizer into EFCOSS and follow a sample session solving a data assimilation problem.

2021 ◽  
Vol 13 (14) ◽  
pp. 7989
Author(s):  
Miriam Pekarcikova ◽  
Peter Trebuna ◽  
Marek Kliment ◽  
Michal Dic

The presented article deals with the issue of solving bottlenecks in the logistics flow of a manufacturing company. The Tx Plant Simulation software tool is used to detect bottlenecks and deficiencies in the company’s production, logistics and transportation systems. Together with the use of simulation methods and lean manufacturing tools, losses in business processes are eliminated and consequently flow throughput is improved. In the TX Plant Simulation software environment, using Bottleneck analyzer, bottlenecks were defined on the created simulation model and a method of optimizing logistics flows was designed and tested by introducing the Kanban pull system. This resulted in an improvement and throughput of the entire logistics flow, a reduction in inter-operational stocks and an increase in the efficiency of the production system as a whole.


2021 ◽  
Vol 11 (5) ◽  
pp. 2042
Author(s):  
Hadi Givi ◽  
Mohammad Dehghani ◽  
Zeinab Montazeri ◽  
Ruben Morales-Menendez ◽  
Ricardo A. Ramirez-Mendoza ◽  
...  

Optimization problems in various fields of science and engineering should be solved using appropriate methods. Stochastic search-based optimization algorithms are a widely used approach for solving optimization problems. In this paper, a new optimization algorithm called “the good, the bad, and the ugly” optimizer (GBUO) is introduced, based on the effect of three members of the population on the population updates. In the proposed GBUO, the algorithm population moves towards the good member and avoids the bad member. In the proposed algorithm, a new member called ugly member is also introduced, which plays an essential role in updating the population. In a challenging move, the ugly member leads the population to situations contrary to society’s movement. GBUO is mathematically modeled, and its equations are presented. GBUO is implemented on a set of twenty-three standard objective functions to evaluate the proposed optimizer’s performance for solving optimization problems. The mentioned standard objective functions can be classified into three groups: unimodal, multimodal with high-dimension, and multimodal with fixed dimension functions. There was a further analysis carried-out for eight well-known optimization algorithms. The simulation results show that the proposed algorithm has a good performance in solving different optimization problems models and is superior to the mentioned optimization algorithms.


Author(s):  
Jiaxi Xia ◽  
Jiangfeng Wang ◽  
Pan Zhao ◽  
Dai Yiping

CO2 in a transcritical CO2 cycle can not easily be condensed due to its low critical temperature (304.15K). In order to increase the critical temperature of working fluid, an effective method is to blend CO2 with other refrigerants to achieve a higher critical temperature. In this study, a transcritical power cycle using CO2-based mixtures which blend CO2 with other refrigerants as working fluids is investigated under heat source. Mathematical models are established to simulate the transcritical power cycle using different CO2-based mixtures under MATLAB® software environment. A parametric analysis is conducted under steady-state conditions for different CO2-based mixtures. In addition, a parametric optimization is carried out to obtain the optimal design parameters, and the comparisons of the transcritical power cycle using different CO2-based mixtures and pure CO2 are conducted. The results show that a raise in critical temperature can be achieved by using CO2-based mixtures, and CO2-based mixtures with R32 and R22 can also obtain better thermodynamic performance than pure CO2 in transcritical power cycle. What’s more, the condenser area needed by CO2-based mixture is smaller than pure CO2.


Author(s):  
Eric Liese

A dynamic process model of a steam turbine, including partial arc admission operation, is presented. Models were made for the first stage and last stage, with the middle stages presently assumed to have a constant pressure ratio and efficiency. A condenser model is also presented. The paper discusses the function and importance of the steam turbines entrance design and the first stage. The results for steam turbines with a partial arc entrance are shown, and compare well with experimental data available in the literature, in particular, the “valve loop” behavior as the steam flow rate is reduced. This is important to model correctly since it significantly influences the downstream state variables of the steam, and thus the characteristic of the entire steam turbine, e.g., state conditions at extractions, overall turbine flow, and condenser behavior. The importance of the last stage (the stage just upstream of the condenser) in determining the overall flowrate and exhaust conditions to the condenser is described and shown via results.


Author(s):  
Michael M. Tiller ◽  
Jonathan A. Dantzig

Abstract In this paper we discuss the design of an object-oriented framework for simulation and optimization. Although oriented around high-level problem solving, the framework defines several classes of problems and includes concrete implementations of common algorithms for solving these problems. Simulations are run by combining these algorithms, as needed, for a particular problem. Included in this framework is the capability to compute the sensitivity of simulation results to the different simulation parameters (e.g. material properties, boundary conditions, etc). This sensitivity information is valuable in performing optimization because it allows the use of gradient-based optimization algorithms. Also included in the system are many useful abstractions and implementations related to the finite element method.


2021 ◽  
Vol 16 (3) ◽  
pp. 155-177
Author(s):  
Shouib Mabdeh ◽  
Tamer Al Radaideh ◽  
Montaser Hiyari

ABSTRACT Thermal comfort has a great impact on occupants’ productivity and general well-being. Since people spend 80–90% of their time indoors, developing the tools and methods that enhance the thermal comfort for building are worth investigating. Previous studies have proved that using passive systems like Trombe walls and solar chimneys significantly enhanced thermal comfort in inside spaces despite that each system has a specific purpose within a specific climate condition. Hence, the main purpose of this study is to design and configure a new, dual functional passive system, called a solar wall. The new system combines the Trombe wall and solar chimney, and it can cool or heat based on building needs. Simulation software, DesignBuilder, has been used to configure the Solar Wall, and study its impact on indoor operative temperature for the base case. Using the new system, the simulation results were compared with those obtained in the base case and analyzed to determine the most efficient system design parameters and implementation method. The case that gave the best results for solar wall configuration was triple glazed glass and 0.1 cm copper as an absorber (case 11). The results show that using four units (case D) achieves longer thermal comfort levels: 15 to 24 thermal hours during winter (compared to five hours maximum) and 10 to 19 comfort hours in summer (compared to zero).


2021 ◽  
Vol 16 (1) ◽  
pp. 139-161
Author(s):  
Shouib Mabdeh ◽  
Tamer Al Radaideh ◽  
Montaser Hiyari

ABSTRACT Thermal comfort has a great effect on occupants’ productivity and general well-being. Since people spend 80–90% of their time indoors, developing the tools and methods that help in enhancing the thermal comfort for buildings are worth investigating. Previous studies have proved that using passive systems like Trombe walls and solar chimneys significantly enhanced thermal comfort in inside spaces despite that each system has a specific purpose within a specific climate condition. Hence, the main purpose of this study is to design and configure a new dual functional passive system, called a solar wall. The new system combines the Trombe wall and solar chimney, and it can cool or heat based on building needs. Simulation software, DesignBuilder, has been used to configure the Solar Wall and study its impact on indoor operative temperature for the base case. Using the new system, the simulation results were compared with those obtained in the base case and analyzed to determine the most efficient system design parameters and implementation method. The case that gave the best results for solar wall configuration was triple glazed glass and 0.1 cm copper as an absorber (case 11). The results show that using four units (case D) achieves longer thermal comfort levels: 15 to 24 thermal hours during winter (compared to five hours maximum) and 10 to 19 comfort hours in summer (compared to zero).


Author(s):  
Alfonso Callejo ◽  
Daniel Dopico

Algorithms for the sensitivity analysis of multibody systems are quickly maturing as computational and software resources grow. Indeed, the area has made substantial progress since the first academic methods and examples were developed. Today, sensitivity analysis tools aimed at gradient-based design optimization are required to be as computationally efficient and scalable as possible. This paper presents extensive verification of one of the most popular sensitivity analysis techniques, namely the direct differentiation method (DDM). Usage of such method is recommended when the number of design parameters relative to the number of outputs is small and when the time integration algorithm is sensitive to accumulation errors. Verification is hereby accomplished through two radically different computational techniques, namely manual differentiation and automatic differentiation, which are used to compute the necessary partial derivatives. Experiments are conducted on an 18-degree-of-freedom, 366-dependent-coordinate bus model with realistic geometry and tire contact forces, which constitutes an unusually large system within general-purpose sensitivity analysis of multibody systems. The results are in good agreement; the manual technique provides shorter runtimes, whereas the automatic differentiation technique is easier to implement. The presented results highlight the potential of manual and automatic differentiation approaches within general-purpose simulation packages, and the importance of formulation benchmarking.


Author(s):  
Srikanth Akkaram ◽  
Jean-Daniel Beley ◽  
Bob Maffeo ◽  
Gene Wiggs

The ability to perform and evaluate the effect of shape changes on the stress, modal and thermal response of components is an important ingredient in the ‘design’ of aircraft engine components. The classical design of experiments (DOE) based approach that is motivated from statistics (for physical experiments) is one of the possible approaches for the evaluation of the component response with respect to design parameters [1]. Since the underlying physical model used for the component response is deterministic and understood through a computer simulation model, one needs to re-think the use of the classical DOE techniques for this class of problems. In this paper, we explore an alternate sensitivity analysis based technique where a deterministic parametric response is constructed using exact derivatives of the complex finite-element (FE) based computer models to design parameters. The method is based on a discrete sensitivity analysis formulation using semi-automatic differentiation [2,3] to compute the Taylor series or its Pade equivalent for finite element based responses. Shape design or optimization in the context of finite element modeling is challenging because the evaluation of the response for different shape requires the need for a meshing consistent with the new geometry. This paper examines the differences in the nature and performance (accuracy and efficiency) of the analytical derivatives approach against other existing approaches with validation on several benchmark structural applications. The use of analytical derivatives for parametric analysis is demonstrated to have accuracy benefits on certain classes of shape applications.


Author(s):  
William W. Finch ◽  
Allen C. Ward

Abstract This paper gives an overview of a system which eliminates infeasible designs from engineering design problems dominated by multiple sources of uncertainty. It outlines methods for representing constraints on sets of values for design parameters using quantified relations, a special class of predicate logic expressions which express some of the causal information inherent in engineering systems. The paper extends constraint satisfaction techniques and describes elimination algorithms that operate on quantified relations and catalogs of toleranced or adjustable parts. It demonstrates the utility of these tools on a simple electronic circuit, and describes their implementation and test in a prototype software tool.


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