A new optimization scheme based on the optimization and calibration method is designed to solve the engine emission problem.A mathematical model which aims to satisfy minimum fuel consumption and emission rules is ***...
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A new optimization scheme based on the optimization and calibration method is designed to solve the engine emission problem.A mathematical model which aims to satisfy minimum fuel consumption and emission rules is *** to the mathematical,trust-region algorithm,ALPS algorithm and genetic algorithm are introduced,and their performance are compared in an actual engine emission ***,two kinds of hybrid algorithms which combine all the algorithms' strong points are put *** results show that the hybrid algorithm is good at the global seach and the result,and the computing time and computation is significantly lower than other optimization algorithm.
This article reviews the history of the development of topology optimization, also describes main material interpolation schemes of continuum structures including homogenization method, variable density method and var...
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This article reviews the history of the development of topology optimization, also describes main material interpolation schemes of continuum structures including homogenization method, variable density method and variable thickness method. Secondly, introduces two optimization algorithms such as Optimality Criteria and Mathematics Programming, each other's strengths and weaknesses are studied. According to our own practical experience, important support structure was used for topology optimization design based on HyperWorks, the results showed the feasibility of topology optimization. Finally, the prospects of development are proposed from above theory and engineering practice.
This paper first presents theoretical research on direct optimization using the Rotate-Vector (RV) algorithm which is suitable for the complex objects and valuable in engineering applications with global optimization ...
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ISBN:
(纸本)9781467314503
This paper first presents theoretical research on direct optimization using the Rotate-Vector (RV) algorithm which is suitable for the complex objects and valuable in engineering applications with global optimization ability. The derivation of the RV algorithm is illustrated in threedimensional space and subsequently extended into multidimensional space. The numerical simulation utilizes this RV algorithm to optimize the parameters of a Proportional-Integral-Differential (PID) controller for an electro-hydraulic system. Simulation results show that the RV algorithm can solve optimization problems without calculating the function gradient.
In this paper we investigate capacity optimization mechanisms for multi-beam satellite systems built on a realistic payload model. The first proposed mechanism deals with long term traffic variations, for which capaci...
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ISBN:
(纸本)9781457720529
In this paper we investigate capacity optimization mechanisms for multi-beam satellite systems built on a realistic payload model. The first proposed mechanism deals with long term traffic variations, for which capacity optimization algorithms are proposed based on per-beam traffic requests. Due to the high asymmetry of the traffic, our algorithms provide time and spatial flexibility illuminating a specific set of beams within a window of several time-slots. Our algorithms maximize the amount of capacity actually offered while providing reduced power consumption. The second proposed mechanism deals with short-term traffic variations, for which we propose Network Coding (NC) based techniques at the link layer. The aim is to increase the offered capacity taking advantage of overlapping beam coverage, usually considered as a source of interference. This technique is meant to be applied not only in classical multi-beam systems, but also on top of the per-beam capacity optimization as a method to deal with fast traffic unbalances not evaluated in the first mechanism. Analysis and simulations results show that system capacity can be increased up to 13% in the first case and up to 90% in the second case.
Carbon exchange between the atmosphere and terrestrial ecosystem is a key component affecting climate changes. Because the in situ measurements are not dense enough to resolve CO2 exchange spatial variation on various...
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Carbon exchange between the atmosphere and terrestrial ecosystem is a key component affecting climate changes. Because the in situ measurements are not dense enough to resolve CO2 exchange spatial variation on various scales, the variation has been mainly simulated by numerical ecosystem models. These models contain large uncertainties in estimating CO2 exchange owing to incorporating a number of empirical parameters on different scales. This study applied a global optimization algorithm and ensemble approach to a surface CO2 flux scheme to (1) identify sensitive photosynthetic and respirational parameters, and (2) optimize the sensitive parameters in the modeling sense and improve the model skills. The photosynthetic and respirational parameters of corn (C4 species) and soybean (C3 species) in NCAR land surface model (LSM) are calibrated against observations from AmeriFlux site at Bondville, IL during 1999 and 2000 growing seasons. Results showed that the most sensitive parameters are maximum carboxylation rate at 25 degrees C and its temperature sensitivity parameter (V-cmax25 and a(vc)), quantum efficiency at 25 degrees C (Q(e25)), temperature sensitivity parameter for maintenance respiration (a(rm)), and temperature sensitivity parameter for microbial respiration (a(mr)). After adopting calibrated parameter values, simulated seasonal averaged CO2 fluxes were improved for both the C4 and the C3 crops (relative bias reduced from 0.09 to -0.02 for the C4 case and from 0.28 to -0.01 for the C3 case). An updated scheme incorporating new parameters and a revised flux-integration treatment is also proposed.
This article reviews the history of the development of topology optimization, also describes main material interpolation schemes of continuum structures including homogenization method, variable density method and var...
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This article reviews the history of the development of topology optimization, also describes main material interpolation schemes of continuum structures including homogenization method, variable density method and variable thickness ***, introduces two optimization algorithms such as Optimality Criteria and Mathematics Programming, each other's strengths and weaknesses are *** to our own practical experience, important support structure was used for topology optimization design based on HyperWorks, the results showed the feasibility of topology ***, the prospects of development are proposed from above theory and engineering practice.
Currently, when calculating the magnetic field generated by the solenoid coil of the superconducting wire wound, we assume that the coil cross section with a uniform current density, but actual current in superconduct...
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Currently, when calculating the magnetic field generated by the solenoid coil of the superconducting wire wound, we assume that the coil cross section with a uniform current density, but actual current in superconducting wires (NbTi) in the form of a wire in channel is not evenly distributed, the current distribution only in the superconducting core, i.e., there is no current in copper, insulation, and filler, and this method of calculation will result in errors. In this paper, we model the superconducting cores of the 1.5-T superconducting magnetic resonance imaging (MRI) magnet to calculate accurate magnetic field intensity and inhomogeneity by helicoidal method in the diameter of spherical volume and find that inhomogeneity is eight times bigger than that calculated by spherical harmonic expansions, which cannot be accepted in design. Hence, in order to design a high-homogeneity MRI magnet, we amend the 1.5-T MRI magnet's original parameters by an optimization algorithm through an original interface between OPERA-3D and MATLAB according to the accurate results.
In general, relative permeability data can be obtained from laboratory coreflooding experiments. Such experimental data can be interpreted analytically or numerically. Compared to analytical methods, when the numerica...
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In general, relative permeability data can be obtained from laboratory coreflooding experiments. Such experimental data can be interpreted analytically or numerically. Compared to analytical methods, when the numerical inversion methods are applied to interpret the coreflooding experimental data, the reservoir performance obtained prior to and after breakthrough can be utilized comprehensively, the capillary effects and the heterogeneity of core samples can also be taken into account, so the estimated result is not only accurate but also complete. Moreover, the numerical inversion methods can be applied to large-scale reservoirs. This article introduces systematically the methodology of numerical inversion methods, and then reviews the present research status. Finally, several proposals of implicitly estimating relative permeability data are put forward from aspects of optimization algorithms’ properties, estimation of endpoint saturations and treatment scale by automatic history matching.
In trading in currency markets, reducing te mean of absolute or squared errors of predicted values is not valuable unless it results in profits. A trading rule is a set of conditions that describe when to buy or sell ...
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In trading in currency markets, reducing te mean of absolute or squared errors of predicted values is not valuable unless it results in profits. A trading rule is a set of conditions that describe when to buy or sell a currency or to close a position, which can be used for automated trading. To optimize the rule to obtain a profit in the future, a probabilistic method such as a genetic algorithm (GA) or genetic programming (GP) is utilized, since the profit is a discrete and multimodal function with many parameters. Although the rules optimized by GA/GP reportedly obtain a profit in out-of-sample testing periods, it is hard to believe that they yield a profit in distant out-of-sample periods. In this paper, we first consider a framework where we optimize the parameters of the trading rule in an in-sample training period, and then execute trades according to the rule in its succeeding out-of-sample period. We experimentally show that the framework very often results in a profit. We then consider a framework in which we conduct optimization as above and then execute trades in distant out-of-sample periods. We empirically show that the results depend on the similarity of the trends in the training and testing periods.
Application of Genetic algorithm and artificial immunization algorithm on getting atmosphere refractivity profile form radar sea clutter (RFC) is introduced. GA can satisfy the nonlinearity, complexity and other speci...
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Application of Genetic algorithm and artificial immunization algorithm on getting atmosphere refractivity profile form radar sea clutter (RFC) is introduced. GA can satisfy the nonlinearity, complexity and other special requirements of RFC. Artificial Immune algorithm can avoid the problems of getting into local optimization, population variety decreasing, and other problems caused by using GA, and the convergence can be improved. The two algorithms are analyzed using the data of radar sea clutter, air sounding, and so on which are acquired in the south sea field, and the quality of two algorithms is gotten, which can be the reference of solving the problem of RFC.
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