Integrated Optimization of Structure and Control Parameters for the Height Control System of a Vertical Spindle Cotton Picker

Vertical picking method is a predominate method used to harvest cotton crop.However,a vertical picking method may cause spindle bending of the cotton picker if spindles collide with stones on the cotton field.Thus,how to realize a precise height control of the cotton picker is a crucial issue to be solved.The objective of this study is to design a height control system to avoid the collision.To design it,the mathematical models are established first.Then a multi-objective optimization model represented by structure parameters and control parameters is proposed to take the pressure of chamber without piston,response time and displacement error of the height control system as the opti-mization objectives.An integrated optimization approach that combines optimization via simulation,particle swarm optimization and simulated annealing is proposed to solve the model.Simulation and experimental test results show that the proposed integrated optimization approach can not only reduce the pressure of chamber without piston,but also decrease the response time and displacement error of the height control system.

Connecting parameters optimization on unsymmetrical twin-tower structure linked by sky-bridge

Based on a simplified 3-DOF model of twin-tower structure linked by a sky-bridge,the frequency response functions,the displacement power spectral density(PSD)functions,and the time-averaged total vibration energy were derived,by assuming the white noise as the earthquake excitation.The effects of connecting parameters,such as linking stiffness ratio and linking damping ratio,on the structural vibration responses were then studied,and the optimal connecting parameters were obtained to minimize the vibration energy of either the independent monomer tower or the integral structure.The influences of sky-bridge elevation position on the optimal connecting parameters were also discussed.Finally,the distribution characteristics of the top displacement PSD and the structural responses,excited by El Centro,Taft and artificial waves,were compared in both frequency and time domain.It is found that the connecting parameters at either end of connection interactively affect the responses of the towers.The optimal connecting parameters can greatly improve the damping connections on their seismic reduction effectiveness,but are unable to reduce the seismic responses of the towers to the best extent simultaneously.It is also indicated that the optimal connecting parameters derived from the simplified 3-DOF model are applicable for two multi-story structures linked by a sky-bridge with dampers.The seismic reduction effectiveness obtained varies from 0.3 to 1.0 with different sky-bridge mass ratio.The displacement responses of the example structures are reduced by approximately 22% with sky-bridge connections.

Structure Parameters Optimization Analysis of Hydraulic Hammer System

In order to improve the impact performance, the structure of hydraulic hammer should be optimized. In this paper, the ranges of eight vital structure parameters of piston and reversing valve system of hydraulic hammer were selected firstly;and then found the best value of different parameters under experiments with the method of computer optimization and the parametric analysis method provided by ADAMS software. These methods worked and the best design values of parameters of hydraulic hammer were obtained. At last, the optimal impact energy of virtual prototype of hydraulic breaking hammer was calculated and compared with the original impact performance. The results reveal that impact performance of hydraulic hammer has been improved significantly.

Optimization of structural parameters for spatial flexible redundant manipulators with maximum ratio of load to mass

Optimization of structural parameters aimed at improving the load carrying capacity of spatial flexible redundant manipulators is presented in this paper. In order to increase the ratio of load to mass of robots, the cross-sectional parameters and constructional parameters are optimized respectively. The cross-sectional and configurational parameters are optimized simultaneously. The numerical simulation of a 4R spatial manipulator is performed. The results show that the load capacity of robots has been greatly improved through the optimization strategies proposed in this paper.

Structural Parameter Optimization of Multilayer Conductors in HTS Cable

In this paper, the design optimization of the structural parameters of multilayer conductors in high temperature superconducting （HTS） cable is reviewed. Various optimization methods, such as the particle swarm optimization （PSO）, the genetic algorithm （GA）, and a robust optimization method based on design for six sigma （DFSS）, have been applied to realize uniform current distribution among the multilayer HTS conductors. The continuous and discrete variables, such as the winding angle, radius, and winding direction of each layer, are chosen as the design parameters. Under the constraints of the mechanical properties and critical current, PSO is proven to be a more powerful tool than GA for structural parameter optimization, and DFSS can not only achieve a uniform current distribution, but also improve significantly the reliability and robustness of the HTS cable quality.

The Structural Design, Simulation Analysis and Parameter Optimization of the Cheetah Robot's Lumbar Vertebrae

The quality of skeleton system for the cheetah robot goes hand in hand with its bionic result of its shape, structure and functions. In view of the skeleton system constitution and structural characteristic of the cheetah, the team applied structure design, stimulation analysis and parameter optimization to developing the cheetah robot. In addition, after the invention of cheetah robot＇s anterior lumbar vertebra based on its functional attribute and connectivity attribute, the Solidworks Simulation was utilized to analyze the design, according to which improvement on the lumbar vertebra was made. Plus, the advantages of the CAD and CAE made the high efficiency of design work and high quality of the cheetah robot possible.

Optimal design of structural parameters for shield cutterhead based on fuzzy mathematics and multi-objective genetic algorithm

In order to improve the strength and stiffness of shield cutterhead, the method of fuzzy mathematics theory in combination with the finite element analysis is adopted. An optimal design model of structural parameters for shield cutterhead is formulated,based on the complex engineering technical requirements. In the model, as the objective function of the model is a composite function of the strength and stiffness, the response surface method is applied to formulate the approximate function of objective function in order to reduce the solution scale of optimal problem. A multi-objective genetic algorithm is used to solve the cutterhead structure design problem and the change rule of the stress-strain with various structural parameters as well as their optimal values were researched under specific geological conditions. The results show that compared with original cutterhead structure scheme, the obtained optimal scheme of the cutterhead structure can greatly improve the strength and stiffness of the cutterhead, which can be seen from the reduction of its maximum equivalent stress by 21.2%, that of its maximum deformation by 0.75%, and that of its mass by 1.04%.

Parameter optimization for plasma-sprayed Al2O3p/Al composite coatings on AZ31 magnesium alloy

Al2O3p/Al composite coatings were prepared on the surface of AZ31 magnesium alloy by plasma spraying technology with mixed powders of Al and Al2O3. An orthogonal test containing six factors and five levels was carried out to acquire the optimum technical parameters. Mierostruetures and properties of the composite coatings were studied. The results show that the coatings consist of Al2O3 particulates distributed uniformly and Al matrix, and the interface between the particulate and matrix is continuous, compact and clean. With increasing the mass fraction of Al2O3 in the mixed powders, the volume fraction of Al2O3 in the coatings iacreases. The Al2O3p/Al composite coating with 14% Al2O3 volume fraction has more compact microstrueture and more satisfactory properties.

Estimation of structural modal parameters by fourier transform with an optimal window

An adaptive Fourier Transform （FT） with an optimal window has been proposed for the time-frequency analysis of nonstationary time series. The method allows for a good estimation of both frequency and amplitude of the spectrum and can be easily applied to the general case of time-varying signals. The evaluation of the proposed approach has been performed on measured time-varying signals from a suspension bridge model and a steel frame model whose data have the typical non-stationary characteristics. The numerical results show that the proposed approach can overcome some of the difficulties encountered in the classic Fourier transform technique and can achieve higher computation accuracy.

Optimization of Honing Wheel Structure Parameters in Ultra-precision Plane Honing

Free abrasive particle machining in simple machine such as: honing, polishing can get higher surface finish mirror, but surface error, and working procedure is hard to control. Therefore, the vertical disposed ultra-precision plane honing method by ultra-particle diamond honing wheel is put forward to. The results of experiments indicate: plane-honing wheel has higher machining accuracy and machining efficiency. But at the same time the structure parameters of honing wheel effects on machining accuracy. By analyzing the relation of honing wheel structure parameters and workpiece machining accuracy, the relation of honing wheel and wear coefficient, then this paper gets honing wheel structure parameters in the condition of best accuracy coefficient and wear coefficient, and resolve the problem of choosing honing wheel structure parameters in ultra-precision plane honing at last. This paper analyses the relation of honing wheel structure parameters and workpiece machining accuracy coefficient and wear coefficient, by building relative movement math model of honing wheel and workpiece in plane honing. Through theory calculating, the result indicate: about honing machine tools for large volume manufacture, honing wheel wear is main effect factor, so honing wheel should adopt obverse triangle radial structure. About honing machining for high accuracy and low-batch quantities, machining accuracy coefficient is main factors; so honing wheel should adopt reverse triangle radial structure. Neglected the manufacturing factors of honing wheel, then we can design honing wheel with high power curve structure to meet the need of machining accuracy coefficient and honing wheel wear coefficient in higher accuracy honing.

Performance-based passive control analysis of adjacent structures:Optimization of Maxwell dampers

The performance-based passive control analysis of the Maxwell dampers between one 10-story and one 6-story adjacent RC frames is conducted in this work.Not only the optimal parameters but also the optimal arrangements of the Maxwell dampers are proposed based on the optimal target of making the total exceeding probability of the adjacent structures to be minimal.The applicability of the analytical expressions of the Maxwell damper damping parameters under different seismic performance targets are firstly examined and then the preferable damping parameters of the Maxwell dampers are proposed through the extensive parametric studies.Furthermore,the optimal arranging positions and optimal arranging numbers of the Maxwell dampers between the adjacent buildings are derived based on a large number of seismic fragility analyses,as well.The general arranging laws of the Maxwell dampers between the adjacent buildings are generated based on the discussion of the theoretical method through the simplified plane model.The optimal parameters and optimal arrangement of the Maxwell dampers presented make both the adjacent structures have preferable controlled effects under each seismic performance target which can satisfy the requirements of multi-performance seismic resistance of the modern seismic codes.

Substructure design optimization and nonlinear responses control analysis of the mega-sub controlled structural system (MSCSS) under earthquake action

The newly proposed mega sub-controlled structure system(MSCSS)and related studies have drawn the attention of civil engineers for practice in improving the performance and enhancing the structural effectiveness of mega frame structures.However,there is still a need for improvement to its basic structural arrangement.In this project,an advanced,reasonable arrangement of mega sub-controlled structure models,composed of three mega stories with different numbers and arrangements of substructures,are designed to investigate the control performance of the models and obtain the optimal model configuration(model with minimum acceleration and displacement responses)under strong earthquake excitation.In addition,the dynamic parameters that affect the performance effectiveness of the optimal model of MSCSS are studied and discussed.The area of the relative stiffness ratio RD,with different mass ratio MR,within which the acceleration and displacement of the optimal model of MSCSS reaches its optimum(minimum)value is considered as an optimum region.It serves as a useful tool in practical engineering design.The study demonstrates that the proposed MSCSS configuration can efficiently control the displacement and acceleration of high rise buildings.In addition,some analytical guidelines are provided for selecting the control parameters of the structure.

DYNAMIC OPTIMIZATION FOR UNCERTAIN STRUCTURES USING INTERVAL METHOD

An interval optimization method for the dynamic response of structures with inter- val parameters is presented.The matrices of structures with interval parameters are given.Com- bining the interval extension with the perturbation,the method for interval dynamic response analysis is derived.The interval optimization problem is transformed into a corresponding de- terministic one.Because the mean values and the uncertainties of the interval parameters can be elected design variables,more information of the optimization results can be obtained by the present method than that obtained by the deterministic one.The present method is implemented for a truss structure.The numerical results show that the method is effective.

Efficient Combination of Topology and Parameter Optimization

This paper presents a combination method of Particle Swarm Optimization (PSO) and topology optimization. With this method a better result can be achieved compared with the sequential application of these two optimization methods. It inherits the ability in finding global optimum from PSO and also suits for discretized design domain. Some special schemes are used in order to provide higher computation efficiency. This method has only been tested with a convex optimization problem. The application in case of a concave problem will be a future study.

Quasilattice-Conserved Optimization of the Atomic Structure of Decagonal Al-Co-Ni Quasicrystals

The detailed atomic structure of quasicrystals has been an open problem for decades. Here we present a quasilattiee-conserved optimization method （quasi-OPT）, under particular quasiperiodic boundary conditions. As the atomic coordinates are described by basic cells and quasilattices, we are able to maintain the self-similarity characteristics of qusicrystals with the atomic structure of the boundary region updated timely following the relaxing region. Exemplified with the study of decagonal Al-Co-Ni （d-Al-Co-Ni）, we propose a more stable atomic structure model based on Penrose quasilattice and our quasi-OPT simulations. In particular, rectangle-triangle ruIes are suggested for the local atomic structures of d-Al-Co-Ni quasicrystals.

Optimization and experimental research on a new-type short cylindrical cup-shaped harmonic reducer

In order to obtain a new-type short cylindrical cup-shaped flexspline that can be applied to space mechanisms,the APDL language of ANSYS software was employed to develop a parameterized equivalent contact model between a flexspline and a wave generator. The validity of the parameterized equivalent contact model was verified by comparing the results of the analytic value of the contact model and the value calculated by the theoretical formula. The curvilinear trend of stress was obtained by changing the structural parameter of the flexspline. Based on the curvilinear trend of stress,multi-objective optimizations of key structural parameters were achieved. Flexspline,wave generator,and circular spline of a new 32-type short cylindrical cup-shaped harmonic reducer were designed and manufactured. A performance test bench to carry out tests on the harmonic reducer was designed. Contrast experiments were implemented to determine the efficiency of the new 32-type short cylindrical cup-shaped harmonic reducer and the conventional 32-type harmonic reducer under different conditions. The experimental results reveal that there is approximately equality in terms of efficiency between the new 32-type short cylindrical cup-shaped harmonic reducer and the conventional 32-type harmonic reducer. The volume of the flexspline of the new 32-type short cylindrical cup-shaped harmonic reducer is reduced by approximately 30% through multi-objective optimization. When the new 32-type short cylindrical cup-shaped harmonic reducer is used on the wheel of a rover prototype,the mass of the wheel hub is decreased by 0.42 kg. Test analysis of wheel motion verifies that the new 32-type short cylindrical cup-shaped harmonic reducer can meet the requirements regarding bearing capacity and efficiency.

A systematic design of multifunctional lattice structures with energy absorption and phononic bandgap by topology and parameter optimization

Lattice structure can realize excellent multifunctional charac-teristics because of its huge design space,and the cellular configuration directly affects the lattice structural performance and lightweight.A novel energy-absorbing multifunctional lat-tice structure with phononic bandgap is presented by topol-ogy and parameter optimization in this paper.First,the two-dimensional(2D)cellular configuration is lightweight designed by using independent continuous mapping(ICM)topology optimization method.The 2D cell is reconstructed by geo-metric parameters and rotated into a three-dimensional(3D)cell by using chiral shape to achieve bandgap.Subsequently,the surrogated model with energy absorption as the object and first-order natural frequency as the constraint is estab-lished to optimize a parametric 3D cell based on the Response Surface Methodology(RSM).Finally,the lattice struc-tures are assembled with dodecagonal staggered arrange-ments to avoid the deformation interference among the adjacent cells.In addition,the lattice structural energy absorp-tion and bandgap characteristics are analyzed and discussed.Compared to Kelvin lattice structure,the optimal lattice struc-ture shows significant improvement in energy absorption effi-ciency.Besides,the proposed design also performs well in damping characteristics of the high-frequency and wide-bandgap.The lattice structural optimization design framework has great meaning to achieve the equipment structural light-weight and multi-function in the aerospace field.

Labyrinth Seal Design Optimization Based on Quadratic Regression Orthogonal Experiment

The influence of labyrinth seal structure parameters and their interaction on the characteristics of leakage amount are numerically investigated by conducting a quadratic regression orthogonal experiment. To determine the optimal structure parameters of the steam seal for minimizing the leakage amount, a reliable regression equation that does not lack of fit is established. The flow characteristics of the fluid in the labyrinth seal are analyzed in detail. Results show that the leakage amount is greatly influenced by seal cavity depth, convex platform height, seal tooth thickness, and tooth tip clearance, with the tip clearance having the most significant effect. The interaction among the four items exerts a certain impact on the leakage amount. The proposed regression equation exhibits a good significance and does not lack of fit. After optimization, the labyrinth seal demonstrates increased entropy and energy dissipation at the tip of the seal tooth, as well as decreased speed and inertia effect in the cavity, suggesting that the resistance leakage performance of the optimized labyrinth seal is improved.

Influence of process parameters on drilling characteristics of Al 1050 sheet with thickness of 0.2 mm using pulsed Nd:YAG laser

The object of this work is to investigate the influence of process parameters on drilling characteristics of an Al 1050 sheet with a thickness of 0.2 mm using a pulsed Nd:YAG laser through numerical analyses and experiments. By comparing the numerical analyses with the experiments, a proper numerical model was obtained. From the results of the numerical analyses and the experiments, the effects of process parameters on entrance diameters of drilled holes, shapes of the holes, taper angles of the holes and temperature distributions in the vicinity of the holes were examined quantitatively. In addition, the optimal drilling condition was estimated to improve the quality of the drilled holes.

Multi-objective Optimization Design and Experimental Investigation of Centrifugal Fan Performance

Current studies of fan performance optimization mainly focus on two aspects： one is to improve the blade profile, and another is only to consider the influence of single impeller structural parameter on fan performance. However, there are few studies on the comprehensive effect of the key parameters such as blade number, exit stagger angle of blade and the impeller outlet width on the fan performance. The G4-73 backward centrifugal fan widely used in power plants is selected as the research object. Based on orthogonal design and BP neural network, a model for predicting the centrifugal fan performance parameters is established, and the maximum relative errors of the total pressure and efficiency are 0.974% and 0.333%, respectively. Multi-objective optimization of total pressure and efficiency of the fan is conducted with genetic algorithm, and the optimum combination of impeller structural parameters is proposed. The optimized parameters of blade number, exit stagger angle of blade and the impeller outlet width are seperately 14, 43.9~, and 21 cm. The experiments on centrifugal fan performance and noise are conducted before and after the installation of the new impeller The experimental results show that with the new impeller, the total pressure of fan increases significantly in total range of the flow rate, and the fan efficiency is improved when the relative flow is above 75%, also the high efficiency area is broadened. Additionally, in 65% -100% relative flow, the fan noise is reduced. Under the design operating condition, total pressure and efficiency of the fan are improved by 6.91% and 0.5%, respectively. This research sheds light on the considering of comprehensive effect of impeller structrual parameters on fan performance, and a new impeller can be designed to satisfy the engineering demand such as energy-saving, noise reduction or solving air pressure insufficiency for power plants.