New Method For Optimal Design Research Articles

Self-Heating Mould for Composite Manufacturing.

The shipbuilding industry, engine manufacturing, aviation, rocket and space technology are promising fields of application for polymeric composite materials. Shape-generating moulding tools with internal heating are used for the creation of a more economically viable method of moulding of internally heated composite structures. The use of a fine-fibered resistive structure in the heated tools allows implementation of effective heating of the composite and elimination of the need for expensive and energy-intensive heating equipment. The aim of this paper was the reduction of energy consumption for internally heated moulding tools by choosing the optimal parameters for their resistive layer. A method for determination of the parameters of the moulding tool resistive layer was developed. This method allows calculation of the heating layer parameters and implementation of the specified time–temperature regime for moulding of the composite structure. It was shown that energy saving for the heated fiberglass shape-generating moulding tools was from 40 to 60%. It was found that the increase in the thickness of the moulded package of the polymeric composite material resulted not only in a higher supplied power for the heating system, but also in a complication of the method for system control, because of the growing exothermic effect of the binder curing reaction. For composite products based on Hysol EA 9396 binder, thicknesses more than 4 mm are critical, because it is not possible to cope with the self-heating effect only by cooling with ambient air already utilized at the twentieth minute of the moulding process. The influence of the physical and mechanical characteristics of the moulding tool material and stiffening ribs was analysed in terms of energy consumption and controllability of the heating system. Fiberglass shows the lowest energy consumption. Heating of the aluminium and steel moulding tools for the same purpose will require 20% and 45% more power, respectively. An increase in the number of stiffening ribs has a strong effect on the heat removal of the heating system. With a small number of aluminium ribs it is not possible to maintain the specified temperature–time regime for a fiberglass moulded package of 5 mm thick with the use of the equipment. However, when the number of stiffeners is increased to 10, the exothermic effect of the reaction becomes smoother and then the heating equipment can cope with the task. An experimental prototype of heating equipment of moulding tools for the manufacturing of structures of polymeric composite materials, as well as a flexible thermal blanket for repair of non-separable structures, were developed. The results can be the basis for a new method of optimal design of parameters of moulding tool structure at minimal heat removal to the environment.

Unraveling the influence of residence time distribution on the performance of reactive distillation – Process optimization and experimental validation

This work is the first to explore the influence and illustrate the impact of the stage average residence time distribution (SARTD) in the reaction section on the performance of reactive distillation (RD) systems, providing guidance for the design of the internals and industrial applications of RD processes. The experimental validation and process optimization were performed using the ethyl levulinate production as case study. Kinetics of the esterification reaction between levulinic acid (LA) and ethanol was explored using an ion exchange resin as catalyst, and then fitted by a pseudo-homogeneous model, providing basic data for subsequent RD pilot-scale experiment and process simulations. The RD experiment was successfully carried out for two catalyst-loading conditions (uniform or non-uniform per stage) to illustrate the impact of SARDT on the RD performance. The experimental results show that the conversion of LA increases by 10.85% (percentage points) after catalyst loading redistribution. A genetic algorithm (GA) with global convergence and fast convergence speed was used to realize the optimization of SARTD instead of using arbitrary settings. The objective function to be minimized was the reboiler duty per unit product (RDP). The optimization results show that the conversion of LA increases by 3.06% (percentage points) and RDP decreases by 10.09% if the SARTD is optimally redistributed. Based on this, it can be predicted that the total catalyst-loading can be reduced by reasonable catalyst redistribution in the industrial applications of RD. In addition, a new method for optimal design of SARTD is proposed, paving the way for optimizing other RD processes.

New Method of Optimal Design of Electrical Rotating Machines

The article presents a new method of the optimal design of the electrical rotating machine based on genetic algorithm. The mathematical description of the proposed algorithm is developed, and the optimal design of the high-speed electrical rotating machine by proposed method is performed. A new method for optimal design allows obtaining a new electrical rotating machine which mass is lower than mass of the initial electrical rotating machine by two times; the value of the rotor active length is lower by 2.37 times and the current density is higher by 1.7 times in comparison with the initial electrical rotating machine. The losses are increased by only 25 percent (power, rotation frequency and materials of both electrical rotating machine are the same).

Power allocation and measurement matrix design for block CS-based distributed MIMO radars

Multiple-input multiple-output (MIMO) radars offer higher resolution, better target detection, and more accurate target parameter estimation. Due to the sparsity of the targets in space-velocity domain, we can exploit Compressive Sensing (CS) to improve the performance of MIMO radars when the sampling rate is much less than the Nyquist rate. In distributed MIMO radars, block CS methods can be used instead of classical CS ones for more performance improvement, because the received signal in this group of MIMO radars is a block sparse signal in a basis. In this paper, two new methods are proposed to improve the performance of the block CS-based distributed MIMO radars. The first one is a new method for optimal energy allocation to the transmitters, and the other one is a new method for optimal design of the measurement matrix. These methods are based on minimizing an upper bound of the sum of the block-coherences of the sensing matrix blocks. Simulation results show an increase in the accuracy of multiple targets parameters estimation for both proposed methods.

Perfect Dynamic Model and Optimal Design of Vibration-Impact Rammer

In order to find a better method of optimal design of vibration-impact rammer, perfect the dynamic model of vibration-impact rammer. Based on the viscoelastic-plastic theory of soil body, the dynamic model and equation set of vibration-impact rammer and soil body system are built. After computer programming, the real-time working data of vibration-impact rammer is obtained and a new method for optimal design of vibration-impact rammer is provided.

Economic optimization of shell and tube heat exchanger based on constructal theory

In this paper, the new approach of constructal theory has been employed to design shell and tube heat exchangers. Constructal theory is a new method for optimal design in engineering applications. The purpose of this paper is optimization of shell and tube heat exchangers by reduction of total cost of the exchanger using the constructal theory. The total cost of the heat exchanger is the sum of operational costs and capital costs. The overall heat transfer coefficient of the shell and tube heat exchanger is increased by the use of constructal theory. Therefore, the capital cost required for making the heat transfer surface is reduced. Moreover, the operational energy costs involving pumping in order to overcome frictional pressure loss are minimized in this method. Genetic algorithm is used to optimize the objective function which is a mathematical model for the cost of the shell and tube heat exchanger and is based on constructal theory. The results of this research represent more than 50% reduction in costs of the heat exchanger.

Optimization Design of Elastic Coupling in Swashplate Engine Based on BP-GA

Aiming at the fact that the current method of designing elastic coupling in swashplate engine is deficient, and the vibration damping effect is inadequate, a new method for optimization design of coupling is put forward based on back propagation artificial neural network and genetic algorithm(BP-GA). Firstly the dynamics model of swashplate engine shafting is set up, and the samples are gained by numerical simulation, then the non-linear mapping relationship of elastic coupling designed parameters of the objective function is established with BP neural network, finally the trained network is called back by GA to make global optimization. The optimization results show that the global optimal resolution can be searched rapidly and correctly with the method, besides, the method is precise, convenient and applicable.

Optimal design of viscous dampers for multi-mode vibration control of bridge cables

Viscous dampers have been widely used for mitigating rain–wind-induced vibration of bridge stay cables. Designing a damper with optimal damping in a specific mode may leave the cable susceptible to vibration in other modes, and it is almost impossible to specify a priori the dominant mode in which optimal performance should be achieved. In the present paper, a new method for optimal design of viscous dampers to achieve multi-mode cable vibration control is developed. With reference to a cable–damper model taking into account cable sag, inclination and bending stiffness, a method to determine the optimal damper size for cable vibration control in assigned multiple modes is proposed based on optimal LQG control theory. The system damping ratios obtained from the proposed strategy are thus found to satisfy the Irwin’s criterion for all the assigned modes. Case studies of prototype cables on a real cable-stayed bridge which experienced rain–wind-induced oscillation show the efficiency of the proposed method.

Optimization design of grinding wheel topography for high efficiency grinding

In view of the limitation of prior topography models of the grinding wheel, a new method for optimization design of grinding wheel topography is advanced. The optimization model can be used to optimize the topography in accordance with machining demands and grinding parameters as well as optimize grinding parameters in accordance with the topography and machining demands. Furthermore, a superabrasive slotted grinding wheel is designed as a practical application of the optimization model and a creep-feed deep grinding experiment is carried out to verify the optimization results.

Optimal design of the coils of an electromagnetic flow meter

A new method of optimal design of the excitation coil for an electromagnetic flow meter is presented, The main goal is to form an algorithm which will be able to deal with natural channels of any shape with conductive beds/banks. The presented method allows an engineer to design an optimal coil to obtain homogeneity of the special weight vector W. This homogeneity provides that the voltage measured between the electrodes of the flow meter will be proportional to the mean velocity of the liquid in the channel. The optimization of the coil shape is carried out through minimization of an objective function defined on the basis of a finite element method 2D model of the cross-section of the channel.

A study on Optimal Design of Bus Transportation Networks Considering The Best Bus Diagram

In order to increase bus trips in urban areas, it is important to improve the service level of bus systems.In this paper, we propose a new method for optimal design of bus transportation networks by Genetic Algorithm. The characteristic of this method is to design the best transportation network by considering not only a set of bus routes but also a bus time table.

Asymptotically Reliable Serial Production Lines: Analysis, Synthesis and a Case Study

This paper presents a model of asymptotically reliable serial production lines and develops a theory for its ana.lysis and synthesis along with a case study of a specific application. As far as the a.nalysis is concerned, a complete asymptotic theory is developed for calculation of the average production rate a.nd steady state buffer occupancy. As far as the synthesis is concerned, a new method of optimal design, referred to as dynamic balancing, is derived and applied to specific synthesis problems. As for the case study, the paper gives the results of the performance analysis of a. pa.int shop operation in a modern automobile assembly plant and shows that the difference between the actual and theoretical data is within 3%. Improvement measures, developed on the basis of the theory presented, brought about 11% increase in the pa.int shop production rate.

Risk-Safety Factor Relation for Storm Sewer Design

Recently, the writers proposed a new method for optimal design of diameters and slopes of pipes of storm sewer networks. Uncertainties from various sources are considered and a tradeoff is made between potential rainstorm flood damages and the coast of installation of the sewers. One key step in the proposed method is the establishment of the risk-safety factor relationship. Through a numerical example, this paper presents the details of procedure to establish the risk-safety factor relationship. The usefulness of the relationship so established is neither restricted to the optimal design method proposed.