Papers by Keyword: Objective Function

Abstract: This paper presents an investigation of the dimension variations on modular magnetorheological (MR) valve with meandering flow path structure. The size variations including the inner and outer radius of the valve at radial path. The first step is conducting FEMM (Finite Element Method Magnetics) to find out the density of magnetic flux on MR valve. The obtained magnetic field density is applied to steady state models to predict pressure drop. To determine the best configuration, pressure drop and operation range are the objective of the selection process. Based on the results, MR valve with 2.75 mm inner radius radial and 9 mm outer radius radial was chosen as the best MR valve design if compared to the other MR valve designs. The results obtained from the MR valve with 2.75 mm inner radius radial and 9 mm outer radius radial are 1.79 Mpa for the pressure drop and 6.68 for the operational range. Keywords: modular magnetorheological valve, optimization, objective function, smart materials

Abstract: The solution to the problem of designing rational load-bearing structures should be associated with the direct use of the principles that govern the deformation of a solid. If the functional of the direct problem has as Euler – Lagrange equations and natural boundary conditions the equations and boundary conditions of the accepted deformation theory, then they must correspond to the functional of the design problem, in addition, to additional equations indicating the dependence of the system energy change on the configuration change and the elastic modules of the body material. Possible variations of the configuration functions and modules of elasticity of the material will be infinitely small changes of the functions satisfying the prescriptive requirements to the structure and material; they are continuous and satisfy the requirements of differentiability. Due to the small variations in the functions that determine the configuration, we neglect changes in the arrangement of external forces relative to individual parts of the body and changes in the temperature field.

Abstract: The wheelchair has become today indispensable for people experiencing various locomotor disabilities. By investigating the current concepts of solutions to improve the ability to move physically, it was attempted to propose a typology to address the mobility problem. On a basic manual wheelchair, a system will be attached to ensure overcoming the obstacles and to guarantee maintaining the stability of the entire wheelchair. This adjustment will improve the user independence and offer the option of attaching a group of wheels to facilitate smooth movement. By using the Ashby’s graphs that compare the ratio between different properties and by calculating the material index, the optimum material will be determine for the developed system. Ansys software was used to study the structural behaviour under the given boundary conditions by determining the total deformation and equivalent Von Misses stress and then comparisons were made between the obtained results. Also, through topology optimization the most strained areas were discovered and measures were proposed to remedy them.

Abstract: Today, artificial implants (AI) industry depends strongly on tribological constitution of the material (s) of the implant. Erosion, corrosion, tribocorrosion and biocorrosion are essential factors to determine both functionality and lifetime of the AIs. Histo-Biocompatibility is also an additional constraint, indispensable for implant manufacturing process. The prediction of durability, based on the computational and experimental study of constituents of AI material (s) are key factors to obtain objective data of any AI characteristics. This contribution deals with a computational comparative analysis of materials for hip implants using Archard’s model mainly. Selected hip implant material hardness are Co-Cr alloy and Titanium types. Method is carried out with specific material data, e.g., hardness or wear constants, nonlinear optimization and graphical subroutines. Results presented are both numerical and graphical. Particular interest is focused on application of the 3D Graphical Optimization method.

Abstract: This study investigated optimum design methods for frame buildings with focus on minimization of economic costs. The methods discussed are intended to provide sufficient reserves for reliability of load-bearing steel structures. The analyzed mathematical models enable to assess seismic resistance of a structure and implement optimum design methods according to the selected key criterion. The available mathematical models assessing economic efficiency of metalwork reinforcement need further development. The model based on the principle of balanced risk is considered as the most appropriate for the study of structural reliability for industrial buildings. This model allows to assess the expected damage as compared with the initial spending on seismic protection. The focus is on setting and implementation of the task whose limiting condition provides equality between expenditures for reinforcement of damaged steel structures and those for damage prevention activities. Minimum of economic costs for construction or reconstruction of a structure is taken as the optimality criterion. This takes into account accumulation of damages within the standard life cycle and changes in stiffness of materials. Assessment of damage risk is based on the life cycle of a structure, its seismic resistance class and spending on damage repair. The study suggests a number of structural solutions that enable to reduce deformation of steel parts of the frame.

Abstract: The aim of this work is to define a general method for the optimization of composite patch repairing. Fracture mechanics theory shows that the stress intensity factor tends towards an asymptotic limit K_∞. This limit is given by Rose’s formula and is a function of the thicknesses and mechanical properties of the cracked plate, the composite patch and the adhesive. The proposed approach consists in considering this limit as an objective function that needs to be minimized. In deed lowering this asymptote will reduce the values of the stress intensity factor hence optimize the repair. However to be effective this robust design must satisfy the stiffness ratio criteria. The resolution of this double objective optimization problem with Matlab program allowed us determine the appropriate geometric and mechanical properties that allow the optimum design; that is the selection of the adhesive, the patch and their respective thicknesses.

Abstract: FCM is a fuzzy segmentation based on overall situation, is typically applied in data mining and pattern recognition. In this paper, the segmentation of brain CT is achieved through FCM clustering algorithm in three-dimensional medical image visualization system, the organization in brain CT processed with FCM clustering can be well identified.However, the connectivity of brain organization is severely damaged. In view of this situation, it is proposed that the object in the brain image through clustering be judged by classification of its neighbor domain. The result shows that this method brings a significant improvement in the problem of organization connectivity brought by FCM clustering. Judging the brain image through FCM clustering by classification of its neighbor domain, a brain CT image of better organization integrity and connectivity can be got.

Abstract: Processes of electrolytic application of metals are used in order to obtain pure coatings, single - or multilayer. Appropriate selection and proper execution contribute to the improvement of product quality, which affects its proper and long functioning. Production costs are not necessarily high. They depend mainly on the proper selection of the coating. The article presents the results of the use of generalized objective function for selection of galvanic coating on metal parts. There were used following criteria in order to characterize the quality (usability): corrosion resistance, mechanical properties, physical properties, gloss, roughness, and economical criteria. Presented method of determining the objective function can be used to choose the optimal coatings for specific service conditions or customer requirements. Presented method of determining the objective function in the design process of the surface layer makes it possible to assess the impact of various factors on the quality of the product and thus gives a chance to make the right choice.

Abstract: The main aim of the paper lies in providing a proposal of technical system optimization in terms of maximizing its reliability when a certain sum of maintenance costs is given, or minimizing maintenance costs to achieve the defined reliability. The technical system is analyzed using the method called fault tree analysis (FTA) and the final diagram is represented by a tree structure. At the top of the diagram, there is an undesired event which represents the system failure. This top event is analyzed and branched into several other events in order to obtain all possible faults of system elements and their combinations which lead to the system failure. Each primary event contains basic information as minimal and maximal reliability and the corresponding maintenance costs. As a result, it is possible to calculate the total probability of system failure, respectively to its reliability, and the total costs needed to ensure the required system reliability. Genetic algorithms are used and applied in the diagram created by FTA. The paper contains the whole proposal of using a genetic algorithm in order to optimize costs and system reliability on the basis of defined conditions. The described proposal is implemented within a functional application and then tested using real data. The results form an integral part of this paper.

Abstract: In this paper, we shall first briefly introduce the hydraulic junction of three-sources branched heat-supply network and the related optimization method. It's difficult to guarantee that the system runs in optimal state and it increases energy consumption in the system. In view of this situation this paper proposes a method to find the optimal positions of hydraulic intersections based on analyzing a real heating system with three heat sources in Jining. The optimization objective is to minimize the electric power consumption of circulating water pumps in district heating system. Finally, optimization programs are designed and the optimized results verify the feasibility and validity of the method compared with conventional experience values.