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Automatic Optimization of Chirp Setting Parameters in Medical Ultrasound Contrast Imaging
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作者 Amira Zaylaa Sebastien Menigot +1 位作者 Jamal Charara Jean-Marc Girault 《Journal of Life Sciences》 2013年第6期592-598,共7页
Medical ultrasound contrast imaging is a powerful modality undergoing successive developments in the last decade to date Lately, pulse inversion has been used in both ultrasound tissue harmonic and contrast imaging. H... Medical ultrasound contrast imaging is a powerful modality undergoing successive developments in the last decade to date Lately, pulse inversion has been used in both ultrasound tissue harmonic and contrast imaging. However, there was a tradeoff between resolution and penetration. Chirp excitations partially solved the tradeoff, but the chirp setting parameters were not optimized. The present work proposes for the first time combining chirp inversion with ultrasound contrast imaging, with the motivation to improve the contrast, by automatically optimizing the setting parameters of chirp excitation, it is thus an optimal command problem. Linear chirps, 5 μm diameter microbubbles and gradient ascent algorithm were simulated to optimize the chirp setting parameters. Simulations exhibited a gain of 5 dB by automatic optimization of chirp inversion relative to pulse inversion. The automatic optimization process was quite fast. Combining chirp inversion with ultrasound contrast imaging led to a maximum backscattered power permitting high contrast outcomes and optimum parameters. 展开更多
关键词 Medical ultrasound contrast imaging chirp inversion chirp setting parameters automatic technique optimal command.
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Phase-Based Optical Flow Method with Optimized Parameter Settings for Enhancing Displacement Measurement Adaptability
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作者 Zhaoxin Peng Menglian Liu +2 位作者 Zhiliang Wang Wei Liu Xian Wang 《Open Journal of Applied Sciences》 2024年第5期1165-1184,共20页
To enhance the applicability and measurement accuracy of phase-based optical flow method using complex steerable pyramids in structural displacement measurement engineering applications, an improved method of optimizi... To enhance the applicability and measurement accuracy of phase-based optical flow method using complex steerable pyramids in structural displacement measurement engineering applications, an improved method of optimizing parameter settings is proposed. The optimized parameters include the best measurement points of the Region of Interest (ROI) and the levels of pyramid filters. Additionally, to address the issue of updating reference frames in practical applications due to the difficulty in estimating the maximum effective measurement value, a mechanism for dynamically updating reference frames is introduced. Experimental results demonstrate that compared to representative image gradient-based displacement measurement methods, the proposed method exhibits higher measurement accuracy in engineering applications. This provides reliable data support for structural damage identification research based on vibration signals and is expected to broaden the engineering application prospects for structural health monitoring. 展开更多
关键词 Displacement Measurement Phase-Based Optical Flow Optimized parameter setting
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Decision Making Algorithmic Approaches Based on Parameterization of Neutrosophic Set under Hypersoft Set Environment with Fuzzy, Intuitionistic Fuzzy and Neutrosophic Settings 被引量:4
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作者 Atiqe Ur Rahman Muhammad Saeed +1 位作者 Sultan S.Alodhaibi Hamiden Abd El-Wahed Khalifa 《Computer Modeling in Engineering & Sciences》 SCIE EI 2021年第8期743-777,共35页
Hypersoft set is an extension of soft set as it further partitions each attribute into its corresponding attribute-valued set.This structure is more flexible and useful as it addresses the limitation of soft set for d... Hypersoft set is an extension of soft set as it further partitions each attribute into its corresponding attribute-valued set.This structure is more flexible and useful as it addresses the limitation of soft set for dealing with the scenarios having disjoint attribute-valued sets corresponding to distinct attributes.The main purpose of this study is to make the existing literature regarding neutrosophic parameterized soft set in line with the need of multi-attribute approximate function.Firstly,we conceptualize the neutrosophic parameterized hypersoft sets under the settings of fuzzy set,intuitionistic fuzzy set and neutrosophic set along with some of their elementary properties and set theoretic operations.Secondly,we propose decision-making-based algorithms with the help of these theories.Moreover,illustrative examples are presented which depict the structural validity for successful application to the problems involving vagueness and uncertainties.Lastly,the generalization of the proposed structure is discussed. 展开更多
关键词 Neutrosophic set hypersoft set neutrosophic hypersoft set parameterized soft set parameterized hypersoft set
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Topology Optimization for Steady-State Navier-Stokes Flow Based on Parameterized Level Set Based Method 被引量:1
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作者 Peng Wei Zirun Jiang +3 位作者 Weipeng Xu Zhenyu Liu Yongbo Deng Minqiang Pan 《Computer Modeling in Engineering & Sciences》 SCIE EI 2023年第7期593-619,共27页
In this paper,we consider solving the topology optimization for steady-state incompressibleNavier-Stokes problems via a new topology optimization method called parameterized level set method,which can maintain a relat... In this paper,we consider solving the topology optimization for steady-state incompressibleNavier-Stokes problems via a new topology optimization method called parameterized level set method,which can maintain a relatively smooth level set function with a local optimality condition.The objective of topology optimization is to􀀀nd an optimal con􀀀guration of theuid and solid materials that minimizes power dissipation under a prescribeduid volume fraction constraint.An arti􀀀cial friction force is added to the Navier-Stokes equations to apply the no-slip boundary condition.Although a great deal of work has been carried out for topology optimization ofuidow in recent years,there are few researches on the topology optimization ofuidow with physical body forces.To simulate theuidow in reality,the constant body force(e.g.,gravity)is considered in this paper.Several 2D numerical examples are presented to discuss the relationships between the proposed method with Reynolds number and initial design,and demonstrate the feasibility and superiority of the proposed method in dealing with unstructuredmesh problems.Three 3D numerical examples demonstrate the proposedmethod is feasible in three-dimensional. 展开更多
关键词 Topology optimization parameterized level set method power dissipation no-slip boundary condition Navier-Stokes equations gravity
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Application of MPSO technique to find optimal location and parameter setting of TCSC
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作者 王延鹏 蔡兴国 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2011年第3期101-105,共5页
A new mothod was presented to find the optimal location and parameter setting of Thyristor Controlled Series Compensator (TCSC) to maxmize the transfer capability.Firstly the sensitivity of the transfer capability wit... A new mothod was presented to find the optimal location and parameter setting of Thyristor Controlled Series Compensator (TCSC) to maxmize the transfer capability.Firstly the sensitivity of the transfer capability with respect was described to the line's reactance was described to find the more sensitive lines for installing TCSC,however,the line which has the most sesitivity value is always not the best line for installing TCSC.For solving this problem,the more sensitive m lines were selected as the alternative line group of installing TCSC,and then modified particle swarm optimization (MPSO) was used to find out the optimal location and the optimal parameter settings of TCSC.Particle swarm optimization (PSO) algorithm can results premature convergence.For solving this problem,population entropy and cellular automata were introduced to it.Simulation results of IEEE 30-bus system proved the effectiveness of the method and its application values. 展开更多
关键词 TCSC optimal location and parameter settings modified particle swarm optimization continuation oower flow
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Effects of transmitter-related parameter settings on ranging accuracy for IR-UWB systems
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作者 吴绍华 张钦宇 张乃通 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2010年第1期51-57,共7页
For impulse radio ultra-wideband (IR-UWB) ranging systems,effects of the settings of transmitter-related parameters, which include the pulse shape, the bandwidth and the pulse repetition interval (PRI), on ranging acc... For impulse radio ultra-wideband (IR-UWB) ranging systems,effects of the settings of transmitter-related parameters, which include the pulse shape, the bandwidth and the pulse repetition interval (PRI), on ranging accuracy were studied through theoretical analysis and simulations. Both the match-filtering based coherent TOA estimation algorithm and the energy-detection based non-coherent algorithm were used during simulations. Results show that the pulse shape has the least effect on the ranging accuracy. Increasing the pulse bandwidth can improve the ranging performance, but the performance is hardly improved any more when the bandwidth is increased beyond a certain level. PRI should be set long enough to guarantee the accurate ranging, because when PRI is shorter than the maximum excess delay of the channel, the ranging accuracy will be deteriorated by inter-pulse interference. 展开更多
关键词 IR-UWB ranging TOA estimation algorithm parameter setting match-filtering energy-detection
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DSAS:A new macromolecular substructure solution program based on the modified phase-retrieval algorithm
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作者 付兴科 谭振希 +2 位作者 耿直 刘茜 丁玮 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第5期125-132,共8页
Considering the pivotal role of single-wavelength anomalous diffraction(SAD) in macromolecular crystallography,our objective was to introduce DSAS,a novel program designed for efficient anomalous scattering substructu... Considering the pivotal role of single-wavelength anomalous diffraction(SAD) in macromolecular crystallography,our objective was to introduce DSAS,a novel program designed for efficient anomalous scattering substructure determination.DSAS stands out with its core components:a modified phase-retrieval algorithm and automated parameter tuning.The software boasts an intuitive graphical user interface(GUI),facilitating seamless input of essential data and real-time monitoring.Extensive testing on DSAS has involved diverse datasets,encompassing proteins,nucleic acids,and various anomalous scatters such as sulfur(S),selenium(Se),metals,and halogens.The results confirm DSAS’s exceptional performance in accurately determining heavy atom positions,making it a highly effective tool in the field. 展开更多
关键词 DSAS single-wavelength anomalous diffraction automated parameters settings phase-retrieval algorithm substructure determination
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Analysis on a Set of 12-parameter Rectangular Plate Element with High Accuracy
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作者 SHI Dong-yang WANG Cai-xia 《Chinese Quarterly Journal of Mathematics》 CSCD 北大核心 2006年第2期159-165,共7页
It is proved that the so-called a set of 12-parameter rectangular plate elements with high accuracy constructed by using double set parameter method and undetermined method are, in fact, the same one; the real shape f... It is proved that the so-called a set of 12-parameter rectangular plate elements with high accuracy constructed by using double set parameter method and undetermined method are, in fact, the same one; the real shape function space is nothing but the Adini's element's, which has nothing to do with the other high degree terms and leads to a new method for constructing the high accuracy plate elements. This fact has never been seen for other conventional and unconventional, conforming and nonconforming rectangular plate elements, such as Quasi-conforming elements, generalized conforming elements and other double set parameter finite elements. Moreover, such kind of rectangular elements can not be constructed by the conventional finite element methods. 展开更多
关键词 double set parameter element high accuracy Adini's shape function space geometric symmetry new method
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An approach to optimize the settings of actuated signals
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作者 Xinguo JIANG Yanjun QIU Sheng RUAN 《Journal of Modern Transportation》 2011年第1期68-74,共7页
Traffic-actuated signal employs relatively complex control logic to regulate traffic flow. Introduction of control variables into the traffic-actuated system contributes to system operational flexibility and complexit... Traffic-actuated signal employs relatively complex control logic to regulate traffic flow. Introduction of control variables into the traffic-actuated system contributes to system operational flexibility and complexity, and also complicates the system with uncertainties. The paper proposes two tentative methods to optimize the actuated signal parameters: basic requirements of controller parameters and analytical model, and macroscopic computer simulation. It is concluded that when the actuated signal operates within the volume/capacity range of 0.4 to 0.6, it will create the most significant benefits; the research suggests that minimum green time in the main street shall be set long enough to meet the required demand, preferably at the 60% of the main street capacity. In order to ensure less control delay in a semi-actuated intersection, relatively small values of vehicle extension (e.g., 2.5 s) and maximum green time are recommended to be assigned to the less important street. 展开更多
关键词 actuated signals OPTIMIZATION parameter settings computer simulation
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Dynamic Setting Method of Assessment Indicators for Power Curves of Renewable Energy Sources Considering Scarcity of Reserve Resources
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作者 Minghao Cao Jilai Yu 《Journal of Modern Power Systems and Clean Energy》 SCIE EI CSCD 2024年第1期101-114,共14页
With the increasing proportion of renewable energy sources(RESs)in power grid,the reserve resource(RR)scarcity for correcting power deviation of RESs has become a potential issue.Consequently,the power curve of RES ne... With the increasing proportion of renewable energy sources(RESs)in power grid,the reserve resource(RR)scarcity for correcting power deviation of RESs has become a potential issue.Consequently,the power curve of RES needs to be more rigorously assessed.The RR scarcity varies during different time periods,so the values of assessment indicators should be dynamically adjusted.The assessment indicators in this paper include two aspects,i.e.,deviation exemption ratio and penalty price.Firstly,this paper proposes a method for dynamically calculating the supply capacity and RR cost,primarily taking into account the operating status of thermal units,forecast information of RES,and load curve.Secondly,after clarifying the logical relationship between the degree of RR scarcity and the values of assessment indicators,this paper establishes a mapping function between them.Based on this mapping function,a dynamic setting method for assessment indicators is proposed.In the future,RES will generally be equipped with battery energy storage systems(BESSs).Reasonably utilizing BESSs to reduce the power deviation of RESs can increase the expected income of RESs.Therefore,this paper proposes a power curve optimization strategy for RESs considering self-owned BESSs.The case study demonstrates that the dynamic setting method of assessment indicators can increase the revenue of RESs while ensuring that the penalty fees paid by RESs to the grid are sufficient to cover the RR costs.Additionally,the power curve optimization strategy can help RESs further increase income and fully utilize BESSs to reduce power deviation. 展开更多
关键词 Renewable energy battery energy storage system(BESS) power curve assessment reserve service parameter setting
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Investigations on Nuclei near Z = 82 in Relativistic Mean Field Theory with FSUGold
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作者 圣宗强 任中洲 《Plasma Science and Technology》 SCIE EI CAS CSCD 2012年第6期534-538,共5页
In this work, the ground-state properties of Pt, Hg, Pb, and Po isotopes have been systematically investigated in the deformed relativistic mean field (RMF) theory with the new parameter set FSUGold. The calculated ... In this work, the ground-state properties of Pt, Hg, Pb, and Po isotopes have been systematically investigated in the deformed relativistic mean field (RMF) theory with the new parameter set FSUGold. The calculated results show that FSUGold is as successful as NL3 in reproducing the ground-state binding energies of the nuclei in this region. The calculated two- neutron separation energies, quadrupole deformations, and root-mean-square charge radii are in agreement with the experimental data. The parameter set FSUGold can successfully describe the shell effect of the neutron magic number N = 126 and give smaller neutron skin thicknesses than NL3 for all the nuclei considered. 展开更多
关键词 relativistic mean field theory parameter set FSUGold binding energy DEFORMATION
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UNSUPERVISED POLINSAR CLASSIFICATION BASED ON OPTIMAL COHERENCE SET
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作者 Xu Liying Li Shiqiang +1 位作者 Deng Yunkai Robert Wang 《Journal of Electronics(China)》 2013年第4期368-376,共9页
Aiming to solve the misclassification problems of unsupervised polarimetric Wishart clas- sification algorithm based on Freeman decomposition, an unsupervised Polarimetric Synthetic Aper- ture Radar (SAR) Interferot... Aiming to solve the misclassification problems of unsupervised polarimetric Wishart clas- sification algorithm based on Freeman decomposition, an unsupervised Polarimetric Synthetic Aper- ture Radar (SAR) Interferotnery (PolInSAR) classification algorithm based on optimal coherence set parameters is studied and proposed. This algorithm uses the result of Freeman decomposition to divide the image into three basic categories including surface scattering, volume scattering, and double-bounce Then, the PolInSAR optimal coherence set parameters are used to finely divide each of the three basic categories into 9 categories, and the whole image is divided into 27 categories. Because both the Freeman decomposition result and optimal coherence set parameters indicate specific scattering characteristics, the whole image is merged into 16 categories based on physical meaning. At last, the Wishart cluster is employed to obtain the final classification result. To preserve the purity of scattering characteristics, pixels with similar scattering characteristics are restricted to be classified with other pixels. The final classification results effectively resolve the misclassification problem, not only the buildings can be effectively distinguished from vegetation in urban areas, but also the road is well distinguished from grass. In this paper, the E-SAR PolInSAR data of German Aerospace Center (DLR) are used to verify the effectiveness of the algorithm. 展开更多
关键词 Polarimetric SAR Interferomery (PolInSAR) Unsupervised classification Freeman de-composition Optimal coherence set parameters
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Starting Control of Free Piston Stirling Linear Generator System Based on FOC
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作者 Qiaoling Yang Kechun Zhang +2 位作者 Shenghui Guo Boliang Song Xiaoyu Zhang 《CES Transactions on Electrical Machines and Systems》 CSCD 2022年第2期195-200,共6页
Aiming at the problem of poor system dynamic performance caused by low parameter matching in the coordinated control of Stirling engine and linear generator in the starting stage control of free piston Stirling linear... Aiming at the problem of poor system dynamic performance caused by low parameter matching in the coordinated control of Stirling engine and linear generator in the starting stage control of free piston Stirling linear generator system,a joint control method of free piston Stirling permanent magnet synchronous linear generator system based on field orientation control is proposed,based on the theoretical derivation of the mathematical model of the system and the principle of controller parameters setting,the simulation experiments of the system starting stage under several Stirling engine working conditions are carried out under simulation.The experimental results show that the stability and rapidity of the system are improved,and the dynamic response speed of generator parameters under different working conditions is accelerated,what fully verifies the correctness and effectiveness of the method.It provides an effective way to improve the control performance of the system and stabilize the power generation operation. 展开更多
关键词 parameter setting Field orientation control Double closed loop Permanent magnet synchronous linear generator
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Parameter Control of Genetic Algorithms by Learning and Simulation of Bayesian Networks——A Case Study for the Optimal Ordering of Tables 被引量:2
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作者 Concha Bielza Juan A. Fernndez del Pozo Pedro Larranaga 《Journal of Computer Science & Technology》 SCIE EI CSCD 2013年第4期720-731,共12页
Parameter setting for evolutionary algorithms is still an important issue in evolutionary computation. There are two main approaches to parameter setting: parameter tuning and parameter control. In this paper, we int... Parameter setting for evolutionary algorithms is still an important issue in evolutionary computation. There are two main approaches to parameter setting: parameter tuning and parameter control. In this paper, we introduce self-adaptive parameter control of a genetic algorithm based on Bayesian network learning and simulation. The nodes of this Bayesian network are genetic algorithm parameters to be controlled. Its structure captures probabilistie conditional (in)dependence relationships between the parameters. They are learned from the best individuals, i.e., the best configurations of the genetic algorithm. Individuals are evaluated by running the genetic algorithm for the respective parameter configuration. Since all these runs are time-consuming tasks, each genetic algorithm uses a small-sized population and is stopped before convergence. In this way promising individuals should not be lost. Experiments with an optimal search problem for simultaneous row and column orderings yield the same optima as state-of-the-art methods but with a sharp reduction in computational time. Moreover, our approach can cope with as yet unsolved high-dimensional problems. 展开更多
关键词 genetic algorithm estimation of distribution algorithm parameter control parameter setting Bayesian network
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TRAPEZOIDAL PLATE BENDING ELEMENT WITH DOUBLE SET PARAMETERS 被引量:1
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作者 Shao-chunChen Dong-yangShi IchiroHagiwara 《Journal of Computational Mathematics》 SCIE CSCD 2003年第4期513-518,共6页
Using double set parameter method, a 12-parameter trapezoidal plate bending element is presented. The first set of degrees of freedom, which make the element convergent, are the values at the four vertices and the mid... Using double set parameter method, a 12-parameter trapezoidal plate bending element is presented. The first set of degrees of freedom, which make the element convergent, are the values at the four vertices and the middle points of the four sides together with the mean values of the outer normal derivatives along four sides. The second set of degree of freedom, which make the number of unknowns in the resulting discrete system small and computation convenient are values and the first derivatives at the four vertices of the element. The convergence of the element is proved. 展开更多
关键词 Plate bending problem Nonconforming finite element Double set parameter method.
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A Model of Spray Tool and a Parameter Optimization Method for Spraying Path Planning 被引量:1
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作者 Ru-Xiang Hua Wei Zou +2 位作者 Guo-Dong Chen Hong-Xuan Ma Wei Zhang 《International Journal of Automation and computing》 EI CSCD 2021年第6期1017-1031,共15页
The digital camouflage spraying of special vehicles carried out by robots can greatly improve the spraying efficiency, spraying quality, and rapid adaptability to personalized patterns. The selection of spray tool and... The digital camouflage spraying of special vehicles carried out by robots can greatly improve the spraying efficiency, spraying quality, and rapid adaptability to personalized patterns. The selection of spray tool and the accuracy of the adopted mathematical spray tool model has a great impact on the effectiveness of spray path planning and spraying quality. Since traditional conical spray tool models are not suitable for spraying rectangular digital camouflage, according to the characteristics of digital camouflage, the coating thickness cumulative distribution model of strip nozzle spray tool for 2 D plane spraying and 3 D surface spraying is derived, and its validity is verified by simulation. Based on the accumulation velocity model of the coating thickness(AVCT) on the curved surface and aiming at spraying path planning within the same surface and different surfaces, a path parameter optimization method based on coating uniformity evaluation of adjacent path overlapping area is proposed. Combined with the vehicle surface model, parameters such as path interval, spray tool angle and spray tool motion velocity can be calculated in real-time to ensure uniform coating. Based on the known local three-dimensional model of vehicle surface and the comprehensive spraying simulation, the validity of the purposed models: the coating thickness on the adjacent path area(CTAPA), the coating thickness on the intersection of two surfaces(CTITS), the coating thickness on the intersection of a plane and a surface(CTIPS), and the optimization method of path parameters are verified. The results show that compared with the traditional spray tool, the strip nozzle can better ensure the uniformity of the coating thickness of digital camouflage spray. Finally, according to a practical spraying experiment, the results prove that the proposed models not only are effective but also meet the practical industrial requirements and are of great practical value. 展开更多
关键词 Digital camouflage spraying robot path optimization parameter setting coating thickness uniformity
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Parameterized level set method for structural topology optimization based on the Cosserat elasticity 被引量:1
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作者 Lianxiong Chen Ji Wan +1 位作者 Xihua Chu Hui Liu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2021年第4期620-630,I0002,共12页
When describing the mechanical behavior of some engineering materials,such as composites,grains,biological materials and cellular solids,the Cosserat continuum theory has more powerful capabilities compared with the c... When describing the mechanical behavior of some engineering materials,such as composites,grains,biological materials and cellular solids,the Cosserat continuum theory has more powerful capabilities compared with the classical Cauchy elasticity since an additional local rotation of point and its counterpart(couple stress)are considered in the Cosserat elasticity to represent the material microscale effects.In this paper,a parameterized level set topology optimization method is developed based on the Cosserat elasticity for the minimum compliance problem of the Cosserat solids.The influence of material characteristic length and Cosserat shear modulus on the optimized structure is investigated in detail.It can be found that the microstructural constants in the Cosserat elasticity have a significant impact on the optimized topology configurations.In addition,the minimum feature size and the geometric complexity of the optimized structure can be controlled implicitly by adjusting the parameters of the characteristic length and Cosserat shear modulus easily.Furthermore,the optimized structure obtained by the developed Cosserat elasticity based parameterized level set method will degenerate to the result by using the classical Cauchy elasticity based parameterized level set method when the Cosserat shear modulus approaches zero. 展开更多
关键词 Structural topology optimization Cosserat continuum theory parameterized level set method Cosserat elasticity Scale effect
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Relativistic Correction on Neutrino Emission from Neutron Stars in Various Parameter Sets
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作者 Wen-Bo Ding Zhan-Qiang Qi +5 位作者 Jia-Wei Hou Geng Mi Tmurbagan Bao Zi Yu Guang-Zhou Liu En-Guang Zhao 《Communications in Theoretical Physics》 SCIE CAS CSCD 2016年第10期474-478,共5页
In the relativistic mean field theory and cooling theories,relativistic correction on neutrino emission from neutron stars in four typical nuclear parameter sets,GM1,GL85,GPS250 and GPS300 is studied.Results show that... In the relativistic mean field theory and cooling theories,relativistic correction on neutrino emission from neutron stars in four typical nuclear parameter sets,GM1,GL85,GPS250 and GPS300 is studied.Results show that relativistic effect makes the neutrino emissivity,neutrino luminosity and cooling rate lower,compared with the nonrelativistic case.And the influence of relativistic effect grows with the mass of the neutron star.GPS300 set leads to the biggest fall in neutrino emissivity,whereas GM1 set leads to the largest disparity in cooling rate caused by relativistic effect. 展开更多
关键词 neutron star neutrino emission relativistic correction parameter set
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Parameter Ecology for Feedback Vertex Set
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作者 Bart M.P.Jansen Venkatesh Raman Martin Vatshelle 《Tsinghua Science and Technology》 SCIE EI CAS 2014年第4期387-409,共23页
This paper deals with the FEEDBACK VERTEX SET problem on undirected graphs, which asks for the existence of a vertex set of bounded size that intersects all cycles. Due it is theoretical and practical importance,the p... This paper deals with the FEEDBACK VERTEX SET problem on undirected graphs, which asks for the existence of a vertex set of bounded size that intersects all cycles. Due it is theoretical and practical importance,the problem has been the subject of intensive study. Motivated by the parameter ecology program we attempt to classify the parameterized and kernelization complexity of FEEDBACK VERTEX SET for a wide range of parameters.We survey known results and present several new complexity classifications. For example, we prove that FEEDBACK VERTEX SET is fixed-parameter tractable parameterized by the vertex-deletion distance to a chordal graph. We also prove that the problem admits a polynomial kernel when parameterized by the vertex-deletion distance to a pseudo forest, a graph in which every connected component has at most one cycle. In contrast, we prove that a slightly smaller parameterization does not allow for a polynomial kernel unless NP coNP=poly and the polynomial-time hierarchy collapses. 展开更多
关键词 feedback vertex set parameterized complexity parameter ecology program structural parameterizations kernelization
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A systematic method of smooth switching LPV controllers design for a morphing aircraft 被引量:17
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作者 Jiang Weilai Dong Chaoyang Wang Qing 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2015年第6期1640-1649,共10页
This paper is concerned with a systematic method of smooth switching linear parameter- varying (LPV) controllers design for a morphing aircraft with a variable wing sweep angle. The morphing aircraft is modeled as a... This paper is concerned with a systematic method of smooth switching linear parameter- varying (LPV) controllers design for a morphing aircraft with a variable wing sweep angle. The morphing aircraft is modeled as an LPV system, whose scheduling parameter is the variation rate of the wing sweep angle. By dividing the scheduling parameter set into subsets with overlaps, output feedback controllers which consider smooth switching are designed and the controllers in over- lapped subsets are interpolated from two adjacent subsets. A switching law without constraint on the average dwell time is obtained which makes the conclusion less conservative. Furthermore, a systematic algorithm is developed to improve the efficiency of the controllers design process. The parameter set is divided into the fewest subsets on the premise that the closed-loop system has a desired performance. Simulation results demonstrate the effectiveness of this approach. 展开更多
关键词 Morphing aircraft parameter set division:Robust control Smooth switching Switched linear parameter-varying system
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