Multi-Factor Optimisation of Large Reflector Antenna Structures

1996 ◽  
Vol 11 (3) ◽  
pp. 307-320 ◽  
Author(s):  
J.S. Liu ◽  
L Hollaway
Keyword(s):  
Mathematical Model ◽  
Evaluation Criteria ◽  
Reflector Antenna ◽  
Objective Functions ◽  
Antenna Structure ◽  
Working Environments ◽  
Design Variables ◽  
Design Requirements ◽  
Optimisation Procedure ◽  
Antenna Reflector

A novel multi-parameter overall situation optimisation method has been developed for use on antenna reflector structures. Various structural performances arc included as objective functions. The design variables involve geometric and size variables of structures. Various working environments and loading cases which affect antenna performances could be combined in the optimisation mathematical model. An important aspect to the work is the establishment of evaluation criteria to optimise the design of a system. Such an optimisation procedure would satisfy extremely high design requirements. An 8m antenna structure is significantly optimised and the results are given.

scholarly journals An approach for the design of multi-material mechanical components

2018 ◽  
Vol 233 (3) ◽  
pp. 960-974 ◽  
Author(s):  
Konstantinos Anyfantis ◽  
Panagiotis Stavropoulos ◽  
Panagis Foteinopoulos ◽  
George Chryssolouris
Keyword(s):  
Structural Design ◽  
Strain Energy ◽  
Computational Procedure ◽  
Partial Replacement ◽  
Objective Functions ◽  
Reinforced Composite ◽  
Design Variables ◽  
Design Requirements ◽  
Strain Energy Minimization ◽  
Good Set

A computational procedure for the calculation of the material parameters involved in the structural design of multi-material components is presented. The developed scheme can be used in the design process for the full or partial replacement of a metallic part with a metal/fiber–reinforced composite bi-material, aiming at weight savings. Finite element simulations are incorporated into an algorithm that rapidly reduces the design space until a good set of design variables has been reached. The process is controlled by two objective functions (mass and strain energy minimization) and is subjected to several constraints according to the component’s design requirements. Three examples have been adopted to demonstrate the effectiveness of the approach. The results show that the upper limit for weight reduction is constrained by the yield strength of the metal component and therefore its corresponding thickness. Based on the design configuration, weight savings up to 25% could be reached.

Multi-Objective Design Problem of Tire Wear and Visualization of Its Pareto Solutions2

2006 ◽  
Vol 34 (3) ◽  
pp. 170-194 ◽  
Author(s):  
M. Koishi ◽  
Z. Shida
Keyword(s):  
Inverse Problems ◽  
Conceptual Design ◽  
Dimensional Space ◽  
Design Stage ◽  
Objective Functions ◽  
Pareto Solutions ◽  
Design Problems ◽  
Multi Objective ◽  
Design Engineers ◽  
Design Variables

Abstract Since tires carry out many functions and many of them have tradeoffs, it is important to find the combination of design variables that satisfy well-balanced performance in conceptual design stage. To find a good design of tires is to solve the multi-objective design problems, i.e., inverse problems. However, due to the lack of suitable solution techniques, such problems are converted into a single-objective optimization problem before being solved. Therefore, it is difficult to find the Pareto solutions of multi-objective design problems of tires. Recently, multi-objective evolutionary algorithms have become popular in many fields to find the Pareto solutions. In this paper, we propose a design procedure to solve multi-objective design problems as the comprehensive solver of inverse problems. At first, a multi-objective genetic algorithm (MOGA) is employed to find the Pareto solutions of tire performance, which are in multi-dimensional space of objective functions. Response surface method is also used to evaluate objective functions in the optimization process and can reduce CPU time dramatically. In addition, a self-organizing map (SOM) proposed by Kohonen is used to map Pareto solutions from high-dimensional objective space onto two-dimensional space. Using SOM, design engineers see easily the Pareto solutions of tire performance and can find suitable design plans. The SOM can be considered as an inverse function that defines the relation between Pareto solutions and design variables. To demonstrate the procedure, tire tread design is conducted. The objective of design is to improve uneven wear and wear life for both the front tire and the rear tire of a passenger car. Wear performance is evaluated by finite element analysis (FEA). Response surface is obtained by the design of experiments and FEA. Using both MOGA and SOM, we obtain a map of Pareto solutions. We can find suitable design plans that satisfy well-balanced performance on the map called “multi-performance map.” It helps tire design engineers to make their decision in conceptual design stage.

Optimization Research on Dynamic Balance of Spatial Engine under Limiting Shaking Moment

2009 ◽  
Vol 626-627 ◽  
pp. 693-698
Author(s):  
Yong Yong Zhu ◽  
S.Y. Gao
Keyword(s):  
Mathematical Model ◽  
Objective Function ◽  
Kinetic Analysis ◽  
Optimization Design ◽  
Design Method ◽  
Dynamic Balance ◽  
Optimized Design ◽  
Design Variables ◽  
The Mathematical Model ◽  
Shaking Moment

Dynamic balance of the spatial engine is researched. By considering the special wobble-plate engine as the model of spatial RRSSC linkages, design variables on the engine structure are confirmed based on the configuration characters and kinetic analysis of wobble-plate engine. In order to control the vibration of the engine frame and to decrease noise caused by the spatial engine, objective function is choosed as the dimensionless combinations of the various shaking forces and moments, the restriction condition of which presents limiting the percent of shaking moment. Then the optimization design is investigated by the mathematical model for dynamic balance. By use of the optimization design method to a type of wobble-plate engine, the optimization process as an example is demonstrated, it shows that the optimized design method benefits to control vibration and noise on the engines and improve the performance practically and theoretically.

Research on the Conformal Phased-Array Antenna

2014 ◽  
Vol 685 ◽  
pp. 324-327
Author(s):  
Shuang Zhao ◽  
Yu Bo Yue
Keyword(s):  
Mathematical Model ◽  
Antenna Array ◽  
Phased Array ◽  
Design Method ◽  
Array Antenna ◽  
Phased Array Antenna ◽  
Conformal Antenna ◽  
Conformal Array ◽  
Design Requirements ◽  
The Mathematical Model

The mathematical model of conformal antenna array is the premise and basis of the conformal array antenna signal processing. Based on the analysis of the antenna array, a design method for adjusting the direction of the conformal array antenna is proposed. Through simulation, the pattern of antenna meets the actual needs of the project and it reaches pre design requirements.

Global Approximation: Performance Comparison of Different Methods, With an Application to Road Vehicle System Engineering

1999 ◽  
Author(s):  
Massimiliano Gobbi ◽  
Giampiero Mastinu
Keyword(s):  
Neural Networks ◽  
Mathematical Model ◽  
Linear Interpolation ◽  
Performance Comparison ◽  
Pareto Optimal ◽  
Approximation Methods ◽  
Global Approximation ◽  
Road Vehicle ◽  
Pareto Optimal Set ◽  
Design Variables

Abstract Optimisation of complex mechanical systems has often to be performed by resorting to global approximation. In usual global approximation practice, the original mathematical model is substituted by another mathematical model which gives approximately the same relationships between design variables and performance indexes. This is made to ensure much faster simulations which are of crucial importance to find optimal solutions. In this paper the performances of four global approximation methods (Neural Networks, Kriging, Quadratic Approximation, Linear Interpolation) are compared, with reference to an actual optimal design problem. The performances of a road vehicle suspension system are optimised by varying the system’s design variables. The Pareto-optimal set is derived symbolically. The performances of the different approximation methods taken into consideration are assessed by comparing the numerical- and the analytical-Pareto-optimal results. It is found that Neural Networks obtain the best accuracy.

A bi-level mathematical model for logistic management considering the evolutionary game with environmental feedbacks

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Peiman Ghasemi ◽  
Fariba Goodarzian ◽  
Angappa Gunasekaran ◽  
Ajith Abraham
Keyword(s):  
Mathematical Model ◽  
Lagrangian Relaxation ◽  
Evolutionary Games ◽  
Relaxation Method ◽  
Objective Functions ◽  
Content Type ◽  
Medical Centers ◽  
Location Routing ◽  
Proposed Model

PurposeThis paper proposed a bi-level mathematical model for location, routing and allocation of medical centers to distribution depots during the COVID-19 pandemic outbreak. The developed model has two players including interdictor (COVID-19) and fortifier (government). Accordingly, the aim of the first player (COVID-19) is to maximize system costs and causing further damage to the system. The goal of the second player (government) is to minimize the costs of location, routing and allocation due to budget limitations.Design/methodology/approachThe approach of evolutionary games with environmental feedbacks was used to develop the proposed model. Moreover, the game continues until the desired demand is satisfied. The Lagrangian relaxation method was applied to solve the proposed model.FindingsEmpirical results illustrate that with increasing demand, the values of the objective functions of the interdictor and fortifier models have increased. Also, with the raising fixed cost of the established depot, the values of the objective functions of the interdictor and fortifier models have raised. In this regard, the number of established depots in the second scenario (COVID-19 wave) is more than the first scenario (normal COVID-19 conditions).Research limitations/implicationsThe results of the current research can be useful for hospitals, governments, Disaster Relief Organization, Red Crescent, the Ministry of Health, etc. One of the limitations of the research is the lack of access to accurate information about transportation costs. Moreover, in this study, only the information of drivers and experts about transportation costs has been considered. In order to implement the presented solution approach for the real case study, high RAM and CPU hardware facilities and software facilities are required, which are the limitations of the proposed paper.Originality/valueThe main contributions of the current research are considering evolutionary games with environmental feedbacks during the COVID-19 pandemic outbreak and location, routing and allocation of the medical centers to the distribution depots during the COVID-19 outbreak. A real case study is illustrated, where the Lagrangian relaxation method is employed to solve the problem.

Multi Objective Design Optimization of Two Bar Truss Using NSGA II and TOPSIS

2014 ◽  
Vol 984-985 ◽  
pp. 419-424
Author(s):  
P. Sabarinath ◽  
M.R. Thansekhar ◽  
R. Saravanan
Keyword(s):  
Design Optimization ◽  
Optimization Problems ◽  
Optimization Methods ◽  
Optimal Solutions ◽  
Objective Functions ◽  
Nsga Ii ◽  
Multi Objective ◽  
Total Displacement ◽  
Design Variables ◽  
Conflicting Objectives

Arriving optimal solutions is one of the important tasks in engineering design. Many real-world design optimization problems involve multiple conflicting objectives. The design variables are of continuous or discrete in nature. In general, for solving Multi Objective Optimization methods weight method is preferred. In this method, all the objective functions are converted into a single objective function by assigning suitable weights to each objective functions. The main drawback lies in the selection of proper weights. Recently, evolutionary algorithms are used to find the nondominated optimal solutions called as Pareto optimal front in a single run. In recent years, Non-dominated Sorting Genetic Algorithm II (NSGA-II) finds increasing applications in solving multi objective problems comprising of conflicting objectives because of low computational requirements, elitism and parameter-less sharing approach. In this work, we propose a methodology which integrates NSGA-II and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) for solving a two bar truss problem. NSGA-II searches for the Pareto set where two bar truss is evaluated in terms of minimizing the weight of the truss and minimizing the total displacement of the joint under the given load. Subsequently, TOPSIS selects the best compromise solution.

Multi-Objective Design Optimization of a Mixed-Flow Pump

2009 ◽  
Author(s):  
Yumiko Takayama ◽  
Hiroyoshi Watanabe
Keyword(s):  
Performance Characteristic ◽  
Performance Characteristics ◽  
Inverse Design ◽  
Surface Model ◽  
Objective Functions ◽  
Mixed Flow ◽  
Multi Objective ◽  
Design Variables ◽  
Flow Head ◽  
Flow Pump

In most cases of high specific speed mixed-flow pump applications, it is necessary to satisfy more than one performance characteristic such as deign point efficiency, shut-off power/head and non-stall characteristic (no positive slope in flow-head curve). However, it is known that these performance characteristics are in relation of trade-offs. As a result, it is difficult to optimize these performance characteristics by conventional way such as trial and error approach by modifying geometrical parameters. This paper presents the results of the multi-objective optimization strategy of mixed-flow pump design by means of three dimensional inverse design approach, Computational Fluid Dynamics (CFD), Design of Experiments (DoE), response surface model (RSM) and Multi Objective Genetic Algorism (MOGA). The parameters to control blade loading distributions and meridional geometries for impeller and diffuser blades in inverse design were chosen as design variables of the optimization process. Pump efficiency, maximum slope in flow-head curve and shut-off power/head were selected as objective functions. Objective functions of pumps, designed by design variables specified in DoE, were evaluated by using CFD. Then, trade-off relations between objective functions were analyzed by using Pareto fronts obtained by MOGA. Some pumps which have specific performance characteristic (non-stall, low shut-off power, high efficiency etc.) designed along the Pareto front were numerically evaluated.

Optimal design of a parallel robotic gripper using enhanced multi-objective ant lion optimizer with a sensitivity analysis approach

2020 ◽  
Vol 40 (5) ◽  
pp. 703-721
Author(s):  
Golak Bihari Mahanta ◽  
Deepak BBVL ◽  
Bibhuti B. Biswal ◽  
Amruta Rout
Keyword(s):  
Sensitivity Analysis ◽  
Distribution Function ◽  
Design Parameters ◽  
Objective Functions ◽  
Content Type ◽  
Multi Objective ◽  
The Past ◽  
Design Variables ◽  
Pick And Place ◽  
Ant Lion

Purpose From the past few decades, parallel grippers are used successfully in the automation industries for performing various pick and place jobs due to their simple design, reliable nature and its economic feasibility. So, the purpose of this paperis to design a suitable gripper with appropriate design parameters for better performance in the robotic production systems. Design/methodology/approach In this paper, an enhanced multi-objective ant lion algorithm is introduced to find the optimal geometric and design variables of a parallel gripper. The considered robotic gripper systems are evaluated by considering three objective functions while satisfying eight constraint equations. The beta distribution function is introduced for generating the initial random number at the initialization phase of the proposed algorithm as a replacement of uniform distribution function. A local search algorithm, namely, achievement scalarizing function with multi-criteria decision-making technique and beta distribution are used to enhance the existing optimizer to evaluate the optimal gripper design problem. In this study, the newly proposed enhanced optimizer to obtain the optimum design condition of the design variables is called enhanced multi-objective ant lion optimizer. Findings This study aims to obtain optimal design parameters of the parallel gripper with the help of the developed algorithms. The acquired results are investigated with the past research paper conducted in that field for comparison. It is observed that the suggested method to get the best gripper arrangement and variables of the parallel gripper mechanism outperform its counterparts. The effects of the design variables are needed to be studied for a better design approach concerning the objective functions, which is achieved by sensitivity analysis. Practical implications The developed gripper is feasible to use in the assembly operation, as well as in other pick and place operations in different industries. Originality/value In this study, the problem to find the optimum design parameter (i.e. geometric parameters such as length of the link and parallel gripper joint angles) is addressed as a multi-objective optimization. The obtained results from the execution of the algorithm are evaluated using the performance indicator algorithm and a sensitivity analysis is introduced to validate the effects of the design variables. The obtained optimal parameters are used to develop a gripper prototype, which will be used for the assembly process.

scholarly journals Metodología para el perfeccionamiento del proceso de enseñanza-aprendizaje de los elementos técnicos-tácticos en los deportes de combate (Methodology for improving the teaching-learning process of technical-tactical elements in combat sports)

Retos ◽  
2017 ◽  
pp. 33-39
Author(s):  
Lisbet Guillen Pereira ◽  
Manuel Copello Janjaque ◽  
Manuel Gutierrez Cruz ◽  
José Ramón Guerra Santiesteban
Keyword(s):  
Mathematical Model ◽  
Learning Process ◽  
Evaluation Criteria ◽  
Practical Aspect ◽  
Wilcoxon Test ◽  
Combat Sports ◽  
High Significance ◽  
Initiation Phase ◽  
Proposal A ◽  
Teaching Learning

El perfeccionamiento de la fase de Iniciación Deportiva compromete muy de cerca el conocimiento de lo novedoso y lo contemporáneo que se deriva del contexto pedagógico y las formas de gestionarlos. Como resultado las metodologías actuantes en cada uno de los deportes reclaman una continua actualización en el orden teórico, metodológico y práctico. En concordancia la presente investigación tuvo por objetivo validar una Metodología para perfeccionar el proceso de enseñanza-aprendizaje de los elementos técnicos tácticos en los deportes de combate, para ello se trabajó con tres disciplinas (Karate, Judo y Taekwondo) seleccionadas de forma intencional las que conformaron una muestra de 265 entrenadores de una población de 852, esta se estratificó en correspondencia con el porcentaje aportado por cada deporte: Judo 96; Karate: 83; Taekwondo: 77, para la validación de la propuesta se elaboró un instrumento compuesto por 12 indicadores, para ello se definieron cinco criterio: Excelente, Muy Bien, Bien, Regular y Mal, a los que se les asignaron código; para darle objetividad a los resultados se utilizó el Modelo Matemático de Tórgerson el cual permitió definir punto de cortes para los criterios de evaluación de la metodología; para la validación de la propuesta se empleó un pre-experimento pedagógico cuyos resultados se compararon mediante el test de Wilcoxon para muestras relacionadas, los resultados arrojaron que en todos los casos la significación fue de p=.002, al ser menor que el valor prefijado p=.05 se rechaza H0 y se acepta Hi, por lo que se demuestra la validez de la metodología.Abstract: Enhancing Sports Initiation phase commits very closely to the knowledge of novel and contemporary issues originated from the pedagogical context, and the ways to manage them. As a result, methodologies applied to any sport discipline demand continuous updating in the theoretical, methodological, and practical aspect. Based on that, the present investigation had the objective to validate a methodology to perfect the learning process of tactical and technical elements in combat sports. Three disciplines (Karate, Judo and Taekwondo) were taken into account, with a sample of 265 coaches selected intentionally from a population of 852, reflecting the proportion of coaches in each discipline: Judo 96; Karate: 83; Taekwondo: 77. An instrument composed of 12 indicators was developed for the validation of the proposal. Five criteria were defined: Excellent, Very Good, Good, Fair and Poor, each of them having been assigned a code; to obtain objective results, we used the Tórgerson Mathematical Model, which allowed to define cut-off points for the methodology evaluation criteria; for the validation of the proposal, a pedagogical pre-experiment was applied. Data were compared employing Wilcoxon test for related samples. Results showed high significance in all cases (p = .002). Therefore, H0 is rejected whereas Hi is accepted, which demonstrates the validity of the methodology.

Sign in / Sign up

Export Citation Format

Share Document