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31.
Ergonomic Chair Design by Fusing Qualitative and Quantitative Criteria Using Interactive Genetic Algorithms 总被引:3,自引:0,他引:3
Brintrup A.M. Ramsden J. Takagi H. Tiwari A. 《Evolutionary Computation, IEEE Transactions on》2008,12(3):343-354
This paper emphasizes the necessity of formally bringing qualitative and quantitative criteria of ergonomic design together, and provides a novel complementary design framework with this aim. Within this framework, different design criteria are viewed as optimization objectives, and design solutions are iteratively improved through the cooperative efforts of computer and user. The framework is rooted in multiobjective optimization, genetic algorithms, and interactive user evaluation. Three different algorithms based on the framework are developed, and tested with an ergonomic chair design problem. The parallel and multiobjective approaches show promising results in fitness convergence, design diversity, and user satisfaction metrics. 相似文献
32.
The design of a rolling system is a multistage process optimization problem involving sequential relationship between consecutive stages. This relationship is peculiar to sequential processes in which the output stock of one stage serves as the input stock into the deforming tool of the other stage. This paper describes the optimization of a real-life rolling system design using a genetic algorithm (GA)-based approach capable of dealing with the sequential nature of this problem. It presents a mathematical model of a real-life rolling system design and explains the proposed optimization approach. Even in the presence of multiple stages, the proposed approach identifies a variety of near-optimal design solutions from which one could be finally chosen based on designer's preferences. It is also shown that the obtained solutions dominate the designs reported in literature. 相似文献
33.
The electrical conductivity, σ, and thermoelectric power, S, of copper chromite (CuCr2O4) are reported in the temperature range 295 to 815 K. A break (T B) in the slope of the plot of log σ against T ?1 was observed around 556 K. Apart from this break, the curves are linear, and their slopes correspond to activation energies of 0.60 eV (T B<556 K) and 1.22 eV (T B>556 K). A break (T′ B) in the slope of the -S against T ?1 plot was also observed round 556 K. Apart from the break at this temperature, the S against T ?1 curves are linear. At T′ B>556, S can be expressed by the relation $$S = - \left[ {\left( {\frac{{0.65 eV}}{{{\text{2}}eT}}} \right) + (0.42) mV K^{ - {\text{1}}} } \right]$$ The mechanism involved in the electrical transport is the hopping of holes from Cr4+ centres to neighbouring Cr3+ ions. The typical hopping mobility of the holes is of the order of 106 m2 V?1 sec?1. The mobility activation energy of the holes in CuCr2O4 decreases with temperature due to the smoothing of the potential barriers between Cr4+ and Cr3+ sites. 相似文献
34.
Different coloured thallous tungstates were prepared by solid state reaction between thallous carbonate and tungsten trioxide at higher temperatures. The structure and thermal stability of different thallous tungstates were determined by powder X-ray diffraction and thermogravimetric analysis, respectively. The electrical conductivity () and thermoelectric power (5) of pressed solid pellets of Tl2WO4 are reported in the temperature range 295 to 950 K. It is concluded that these materials have large numbers of oxygen ion vacancies and conduction occurs due to the electrons left by oxygen ions while escaping the solid. These electrons are trapped in the valence band and form centres analogous to a helium atom and electrical conductivity results when they enter the conduction band. The values of donor ionization energies have also been evaluated. 相似文献
35.
In the current study a meshfree Lagrangian particle method for the Landau–Lifshitz Navier–Stokes (LLNS) equations is developed. The LLNS equations incorporate thermal fluctuation into macroscopic hydrodynamics by the addition of white noise fluxes whose magnitudes are set by a fluctuation–dissipation theorem. The study focuses on capturing the correct variance and correlations computed at equilibrium flows, which are compared with available theoretical values. Moreover, a numerical test for the random walk of standing shock wave has been considered for capturing the shock location. 相似文献
36.
The present paper deals with the variational approach for solving a clamped rectangular plate under a uniform load. The increasing use of composite materials for plate-type structures intensified the need for solutions of rectangular plates. The variational approach has a broad range of applications in solid mechanics. The methods used to solve the problem consider the minimum total potential energy approach. The maximum deflection is obtained for a square plate by the Ritz, Galerkin and Kantorovich methods. The aim of this paper is to find an approximate solution of higher accuracy. Numerical results for various components of stresses are found and plotted in the form of curves. The results obtained by various methods are compared with those reported earlier. The results show reasonable agreement with the known results, but with a simple and practical approach. The physical aspect of the concept is the immediate use of these results in solid and structural mechanics. 相似文献
37.
Ashesh K. Sinha W.J. Zhang M.K. Tiwari 《Engineering Applications of Artificial Intelligence》2012,25(8):1628-1643
This article is betrothed to serve as a continuation of the emerging swarm techniques to solve supply chain problems. Our aim is to map some of the pressing research challenges contributed by the artificial intelligence community and to develop an improved algorithm: Co-evolutionary immuno-particle swarm optimisation with penetrated hyper-mutation (COIPSO-PHM). In this paper, we proposed a new algorithm which uses clonal selection approach in particle swarm optimisation by embedding co-evolutionary theory to solve the problem of inventory replenishment in distributed plant–warehouse–retailer system. Constraint handling is explicitly taken care by implanting augmented lagrangian concept. To demonstrate the efficiency of the algorithm, its performance are evaluated and compared on 10 benchmarked problems (made constrained problem via random initialisation in the infeasible zone) including functions with uni-modalities as well as multi-modalities. The result follows shows superior performance of the algorithm in every respect. 相似文献
38.
A study on fitness-for-service assessment for crack-like defects and corrosion in nuclear reactor pressure tubes 总被引:1,自引:0,他引:1
Rakesh Sehgal Ashutosh Tiwari Vivek Sood 《Reliability Engineering & System Safety》2005,89(2):227-235
This paper looks forward to thoroughly assess zirconium alloy (Zr-2) pressure tubes used in nuclear power reactors for crack like and corrosion type defects. It emphasizes on the use of reliability concept for determining the probability of failure of zirconium alloy pressure tubes based on deuterium ingress. The in depth analysis carried out to calculate the reliability index for the above two problems is based on FORM approach. A steady state corrosion rate is assumed to estimate the growth in the dimensions of corrosion defects. The methodology suggested in this paper is useful for designers and plant engineers in timely detection of the cracks and leaks in the pressure tubes used in nuclear reactors and initiate suitable corrective actions based on their criticality. 相似文献
39.
Majority of the products can be assembled in several ways that means the same final product can be realized by different sequences of assembly operations. Different degree of difficulty is associated with each sequence of assembly operation and such difficulties are caused by the different mechanical constraints forced by the different sequences of operations. In the past, few notable attempts have been made to represent and enumerate the degree of difficulty associated with an assembly sequence (in the form of triangular fuzzy number) by using the concept of assembly graph. However, such representation schemes do not possess the capabilities to model the user's reasoning and preferences. In this research, an intelligent Petri net model that combines the abilities of modelling, planning and performance evaluation for assembly operation is presented. This modelling tool can represent the issues concerning degree of difficulty associated with assembly sequences. The proposed mechanism is enhanced expert high-level colored fuzzy Petri net (EEHLCFPN) that is a hybrid of knowledge-based system and colored Petri net. An example encompassing assembly of subassemblies is considered to efficiently delineate the modelling capabilities of proposed hybrid petri net model. 相似文献
40.
Ring shear tests were conducted on five samples of different nature with a modified Imperial College type ring shear machine. The three different testing methods used, (1) individual sample testing for each normal stress, (2) increasing load multistage ring shear test, and (3) reducing load multistage ring shear test, all showed similar effective residual internal friction angle for the samples, irrespective of testing method. However, effective residual shear intercept was different according to the testing methodology. The internal friction angle did not vary, particularly after the first minimum point in the stress displacement curve, although the residual shear intercept decreased with increase in the displacement. The thickness of the shearing zone increased along with the displacement. The remolded peak shear strength for saturated conditions at field dry density varied with the consolidation history. Measurement of remolded peak shear strength was possible in a single sample using the increasing load multistage ring shear test at normal consolidation. The equilibrium water content of the sample after the ring shear test was nearly equal to the plastic limit. 相似文献