scholarly journals Enhanced linear reformulation for engineering optimization models with discrete and bounded continuous variables

2018 ◽  
Vol 58 ◽  
pp. 140-157 ◽  
Author(s):  
Qi An ◽  
Shu-Cherng Fang ◽  
Han-Lin Li ◽  
Tiantian Nie
Keyword(s):  
Optimization Models ◽  
Engineering Optimization ◽  
Continuous Variables ◽  
Linear Reformulation

Constrained Structural Optimization of Electro-Thermal Microactuator Using Double Chromosome Genetic Evolution

2013 ◽  
Vol 677 ◽  
pp. 136-141
Author(s):  
Chien Jong Shih ◽  
Po Hung Lin
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Double Helix ◽  
Optimization Models ◽  
Engineering Optimization ◽  
Genetic Evolution ◽  
Element Analysis ◽  
Design Constraints ◽  
Double Chromosome

This paper presents two design optimization models for U-type electro-thermal microactuator. The result shows that the unequal arm model has better performance than the equal arm model. The models were solved by finite element analysis that are verified and comparison to publish paper and then are utilized in optimum design. The feature of presenting work contains temperature constraints to avoid the harm of operating object and decrease stress concentration on flexure. For handling design constraints, a method named double chromosome genetic evolution (DCGE) is developed in gene based algorithm. The idea of the presenting constrained strategy was inspired from the gene evolved by double helix chromosome of expressing certain traits. The constrained evolutionary algorithm proposed in this work is efficient and reliable. It can be integrated into a broad field of engineering optimization.

scholarly journals An Efficient Framework for Multi-Objective Risk-Informed Decision Support Systems for Drainage Rehabilitation

2020 ◽  
Vol 25 (4) ◽  
pp. 73
Author(s):  
Xiatong Cai ◽  
Abdolmajid Mohammadian ◽  
Hamidreza Shirkhani
Keyword(s):  
Optimization Problems ◽  
Drainage System ◽  
Mixed Integer ◽  
Engineering Optimization ◽  
Continuous Variables ◽  
Objective Functions ◽  
Multi Objective Optimization ◽  
Integer Optimization ◽  
Framework Structure ◽  
Multi Objective

Combining multiple modules into one framework is a key step in modelling a complex system. In this study, rather than focusing on modifying a specific model, we studied the performance of different calculation structures in a multi-objective optimization framework. The Hydraulic and Risk Combined Model (HRCM) combines hydraulic performance and pipe breaking risk in a drainage system to provide optimal rehabilitation strategies. We evaluated different framework structures for the HRCM model. The results showed that the conventional framework structure used in engineering optimization research, which includes (1) constraint functions; (2) objective functions; and (3) multi-objective optimization, is inefficient for drainage rehabilitation problem. It was shown that the conventional framework can be significantly improved in terms of calculation speed and cost-effectiveness by removing the constraint function and adding more objective functions. The results indicated that the model performance improved remarkably, while the calculation speed was not changed substantially. In addition, we found that the mixed-integer optimization can decrease the optimization performance compared to using continuous variables and adding a post-processing module at the last stage to remove the unsatisfying results. This study (i) highlights the importance of the framework structure inefficiently solving engineering problems, and (ii) provides a simplified efficient framework for engineering optimization problems.

Modeling And Optimization Of The Construction Organization's Production Program

2020 ◽  
pp. 49-56
Keyword(s):  
Software Package ◽  
Target Function ◽  
Optimization Models ◽  
Labor Resource ◽  
Production Program ◽  
Construction Organizations ◽  
Source Data ◽  
Labor Resources ◽  
Construction Organization ◽  
Planning Production

In the article, the author considers the problems of complex algorithmization and systematization of approaches to optimizing the work plans of construction organizations (calendar plans) using various modern tools, including, for example, evolutionary algorithms for "conscious" enumeration of options for solving a target function from an array of possible constraints for a given nomenclature. Various typical schemes for modeling the processes of distribution of labor resources between objects of the production program are given, taking into account the array of source data. This data includes the possibility of using the material and technical supply base (delivery, storage, packaging) as a temporary container for placing the labor resource in case of released capacity, quantitative and qualification composition of the initial labor resource, the properties of the construction organization as a counterparty in the contract system with the customer of construction and installation works etc. A conceptual algorithm is formed that is the basis of the software package for operational harmonization of the production program ( work plans) in accordance with the loading of production units, the released capacities of labor resources and other conditions stipulated by the model. The application of the proposed algorithm is most convenient for a set of objects, which determines the relevance of its implementation in optimization models when planning production programs of building organizations that contain several objects distributed over a time scale.

Preoperative MRI findings and prediction of diagnostic utility of foramen ovale electrodes

2020 ◽  
Vol 132 (3) ◽  
pp. 692-699 ◽  
Author(s):  
Sarah K. Bick ◽  
Marjan S. Dolatshahi ◽  
Benjamin L. Grannan ◽  
Andrew J. Cole ◽  
Daniel B. Hoch ◽  
...  
Keyword(s):  
Minimally Invasive ◽  
Treatment Decision ◽  
Temporal Lobectomy ◽  
Categorical Variables ◽  
Continuous Variables ◽  
Foramen Ovale ◽  
Mri Findings ◽  
Noninvasive Methods ◽  
Diagnostic Modality ◽  
Diagnostic Investigations

OBJECTIVEForamen ovale electrodes (FOEs) are a minimally invasive method to localize mesial temporal seizures in cases in which noninvasive methods are inconclusive. The objective of this study was to identify factors predicting the ability of FOEs to yield a diagnosis in order to determine optimal candidates for this procedure.METHODSAll cases of diagnostic investigations performed with FOEs at the authors’ institution between 2005 and 2017 were reviewed. FOE investigation was defined as diagnostic if it led to a treatment decision. Demographic and clinical variables for diagnostic and nondiagnostic investigations were compared using a Wilcoxon rank-sum test for continuous variables and Fisher’s exact test for categorical variables.RESULTSNinety-three patients underwent investigations performed with FOEs during the study period and were included in the study. FOE investigation was diagnostic in 75.3% of cases. Of patients who underwent anterior temporal lobectomy following diagnostic FOE evaluation, 75.9% were Engel class I at last follow-up (average 40.1 months). When the diagnostic and nondiagnostic FOE groups were compared, patients who had diagnostic investigations were more likely to be male (57.1% male vs 26.1% in the nondiagnostic group, p = 0.015). They were also more likely to have temporal lesions on preoperative MRI (p = 0.018).CONCLUSIONSFOEs are a useful, minimally invasive diagnostic modality resulting in a treatment decision in 75% of cases. Male patients and patients with temporal lesions on MRI may be most likely to benefit from FOE investigation.

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