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Asymptotic Probability of Record Numbers in Random Walks
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作者 PENG Wenjie LI Yuqiang 《应用概率统计》 北大核心 2025年第1期17-27,共11页
In this paper,large deviations principle(LDP)and moderate deviations principle(MDP)of record numbers in random walks are studied under certain conditions.The results show that the rate functions of LDP and MDP are dif... In this paper,large deviations principle(LDP)and moderate deviations principle(MDP)of record numbers in random walks are studied under certain conditions.The results show that the rate functions of LDP and MDP are different from those of weak record numbers,which are interesting complements of the conclusions by Li and Yao[1]. 展开更多
关键词 random walk record number large deviation moderate deviation
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The noise analysis and multi-physical field coupling study of high-precision SERF atomic gyroscopes
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作者 Jiaxin Liu Xusheng Lei +3 位作者 Yu Yuan Yizhe Zhou Haoying Pang Zhihong Wu 《Defence Technology(防务技术)》 2025年第8期213-224,共12页
The spin-exchange relaxation-free atomic gyroscope,with its exceptionally high theoretical precision,demonstrates immense potential to become the next-generation strategic-grade gyroscope.However,due to technological ... The spin-exchange relaxation-free atomic gyroscope,with its exceptionally high theoretical precision,demonstrates immense potential to become the next-generation strategic-grade gyroscope.However,due to technological noise,there is still a significant gap between its actual precision and theoretical precision.This study identifies the key factor limiting the precision of the SERF gyroscope as coupling noise.By optimizing the detection loop structure,a distinction between the dual-axis signals'response to optical and magnetic fields was achieved-where the optical errors responded similarly,while the response to magnetic noise was opposite.Based on the differences in the optical-magnetic response of the dual-axis signals,empirical mode decomposition was used to decompose the dual-axis gyroscope signals into multiple intrinsic mode functions,and Allan deviation analysis was applied to analyze the noise characteristics of the intrinsic mode functions over various periods.This study successfully reveals that optical errors caused by thermal-optical coupling and long-period magnetic noise induced by thermal-magnetic coupling are the dominant factors limiting the long-term stability of the SERF gyroscope.Based on these analyses,the study concludes that to achieve strategic-grade precision for the SERF gyroscope,it is essential to effectively address the noise issues caused by multi-physical field couplings. 展开更多
关键词 SERF gyroscope Empirical mode decomposition Allan deviation Noise feature recognition Multi physics field coupling
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An automatic unified modeling method of geological object and engineering object based on tri-prism(TP) 被引量:1
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作者 张荣春 李浩 +1 位作者 吴铭飞 王亚芹 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第4期1419-1426,共8页
For the interaction relation between geological object and engineering object in some fields related to water conservancy and hydropower, a unified modeling idea was proposed. On the basis of summarizing both advantag... For the interaction relation between geological object and engineering object in some fields related to water conservancy and hydropower, a unified modeling idea was proposed. On the basis of summarizing both advantages and disadvantages of existing modeling methods, an automatic unified modeling method of both engineering and geological objects based on tri-prism(TP) model was presented. Through the lossless correction algorithm of deviated drill holes contained in this method, the real deviated drill holes could be corrected into the equivalent virtual vertical ones. And the correction accuracy fully meets the requirements of unified modeling. With the virtual vertical drilling data, TIN construction of both cover layer and other stratums would be built in order to obtain the 3D geological model. Then, the engineering design data would be introduced into the 3D geological model for achieving unified modeling. For this process, the volume subdividing and restructuring principles were introduced to deal with the spatial relationships between engineering object and geological object. In order to improve the efficiency of unified modeling, the reconstruction of TIN based on constraint information was also applied in this method. At last, the feasibility and validation of the unified modeling method as well as its relevant key algorithms were verified by specific experiments and analysis of results. 展开更多
关键词 tri-prism(TP) model unified modeling deviated drill holes correction volume subdividing constraint information
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美国诗人安妮“孩子出生以前”一诗的平易风格(英文)
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作者 蒋颖 《思想战线》 CSSCI 北大核心 2011年第S1期346-348,共3页
The poem "Before the Birth of One of Her Children" by American Puritan Poet Anne Bradstreet is a perfect illustration of the plain style.Plainness in both the content and language makes this poem enduring ve... The poem "Before the Birth of One of Her Children" by American Puritan Poet Anne Bradstreet is a perfect illustration of the plain style.Plainness in both the content and language makes this poem enduring verse. 展开更多
关键词 PLAIN STYLE PURITAN deviation
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洗涤用蛋白酶PB92的分子动力学模拟 被引量:1
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作者 郭雨飞 张剑 于文 《日用化学工业》 CAS 北大核心 2021年第4期299-305,共7页
以蛋白酶PB92结构为基础,分别对无底物结合和有底物结合的蛋白酶PB92进行了分子动力学(MD)模拟来研究其动力学特性,研究得到了有、无底物结合的蛋白酶PB92的结构性质,并进行了比较,进而评估与底物结合后蛋白酶PB92在结构性特征以及稳定... 以蛋白酶PB92结构为基础,分别对无底物结合和有底物结合的蛋白酶PB92进行了分子动力学(MD)模拟来研究其动力学特性,研究得到了有、无底物结合的蛋白酶PB92的结构性质,并进行了比较,进而评估与底物结合后蛋白酶PB92在结构性特征以及稳定性上发生的一系列变化。实验结果表明,在动力学模拟过程中,有底物结合的蛋白酶PB92的构象比无底物结合的蛋白酶PB92的构象更加致密稳定,表现出符合“诱导契合”反应的模式。对未来更适用于洗涤用品工业的蛋白酶性能和结构的开发提供理论基础和指引。 展开更多
关键词 蛋白酶PB92 分子动力学模拟 Root Mean Square Deviation(RMSD)
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An Improved Model for Calculating CO_2 Solubility in Aqueous NaCl Solutions and the Application to CO_2-H_2O-NaCl Fluid Inclusions 被引量:8
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作者 毛世德 《矿物学报》 CAS CSCD 北大核心 2013年第S2期480-480,共1页
To determine compositions,homogenization pressures and isopleths of CO2-H2O-NaCl fluid inclusions,an improved activity-fugacity model is developed to calculate CO2solubility in aqueous NaCl solutions.The model can pre... To determine compositions,homogenization pressures and isopleths of CO2-H2O-NaCl fluid inclusions,an improved activity-fugacity model is developed to calculate CO2solubility in aqueous NaCl solutions.The model can predict the solubility of CO2in aqueous NaCl solutions from 273 K to 723 K,from1 bar to 1500 bar and from 0 to 4.5 mol kg-1of NaCl,within or close to experimental uncertainties.The average deviation between the solubility predicted 展开更多
关键词 SOLUBILITY deviation HOMOGENIZATION heating MOLAR mixtures iterative HOMOGENOUS updated
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Using the Method of Maximizing Deviation to Make Decision for M ultiindices 被引量:12
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作者 Wang Yingming Department of Automation, Xiamen University, 361005, P. R. China 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 1997年第3期21-26,共6页
This paper takes the synthesizing evaluation about industrial economic benefits by examples and proposes a new method named maximizing deviation method for multiindices decision. The new method can automatically deter... This paper takes the synthesizing evaluation about industrial economic benefits by examples and proposes a new method named maximizing deviation method for multiindices decision. The new method can automatically determine the weight coefficients among the multiindices and also can obtain the exact and reliable evaluation results without subjectivity. 展开更多
关键词 Multiindices decision Multiindices ranking Economic benefits evaluation Maximizing deviation method.
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Novel combinatorial algorithm for the problems of fuzzy grey multi-attribute group decision making 被引量:13
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作者 Rao Congjun Xiao Xinping Peng Jin 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2007年第4期774-780,共7页
To study the fuzzy and grey information in the problems of multi-attribute group decision making, the basic concepts of both fuzzy grey numbers and grey interval numbers are given firstly, then a new model of fuzzy gr... To study the fuzzy and grey information in the problems of multi-attribute group decision making, the basic concepts of both fuzzy grey numbers and grey interval numbers are given firstly, then a new model of fuzzy grey multi-attribute group decision making based on the theories of fuzzy mathematics and grey system is presented. Furthermore, the grey interval relative degree and deviation degree is defined, and both the optimistic algorithm of the grey interval relational degree and the algorithm of deviation degree minimization for solving this new model are also given. Finally, a decision making example to demonstrate the feasibility and rationality of this new method is given, and the results by using these two algorithms are uniform. 展开更多
关键词 multi-attribute group decision making fuzzy grey number grey interval relational degree deviation degree
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Numerical simulation analysis for deformation deviation and experimental verification for an antenna thin-wall parts considering riveting assembly with finite element method 被引量:8
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作者 PAN Ming-hui TANG Wen-cheng +1 位作者 XING Yan NI Jun 《Journal of Central South University》 SCIE EI CAS CSCD 2018年第1期60-77,共18页
In the process of thin-wall parts assembly for an antenna,the parts assembly deformation deviation is occurring due to the riveting assembly.In view of the riveting assembly deformation problems,it can be analyzed thr... In the process of thin-wall parts assembly for an antenna,the parts assembly deformation deviation is occurring due to the riveting assembly.In view of the riveting assembly deformation problems,it can be analyzed through transient and static simulation.In this work,the theoretical deformation model for riveting assembly is established with round head rivet.The simulation analysis for riveting deformation is carried out with the riveting assembly piece including four rivets,which comparing with the measuring points experiment results of riveting test piece through dealing with the experimental data using the point coordinate transform method and the space line fitting method.Simultaneously,the deformation deviation of the overall thin-wall parts assembly structure is analyzed through finite element simulation;and its results are verified by the measuring experiment for riveting assembly with the deformation deviation of some key points on the thin-wall parts.Through the comparison analysis,it is shown that the simulation results agree well with the experimental results,which proves the correctness and effectiveness of the theoretical analysis,simulation results and the given experiment data processing method.Through the study on the riveting assembly for thin-wall parts,it will provide a theoretical foundation for improving thin-wall parts assembly quality of large antenna in future. 展开更多
关键词 thin-wall parts assembly assembly deformation deviation theoretical deformation model finite element simulation measuring experiment
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Research on ballistic missile laser SIMU error propagation mechanism 被引量:5
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作者 Wei Shihui Xiao Longxu 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2008年第2期356-362,共7页
It is necessary that the laser inertial system is used to further improve the fire accuracy and quick reaction capability in the ballistic missile strapdown inertial navigation system. According to the guidance contro... It is necessary that the laser inertial system is used to further improve the fire accuracy and quick reaction capability in the ballistic missile strapdown inertial navigation system. According to the guidance controlling method and the output and error model of ballistic missile laser SIMU, the mathematical model of error propagation mechanism is set up and any transfer environmental function of error coefficient that affects the fire accuracy is deduced. Also, the missile longitudinal/lateral impact point is calculated using MATLAB. These establish the technical foundation for further researching the dispersion characteristics of impact point and reducing the laser guidance error. 展开更多
关键词 ballistic missile laser SIMU instrument error impact point deviations environmental function.
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A continuous differentiable wavelet threshold function for speech enhancement 被引量:3
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作者 贾海蓉 张雪英 白静 《Journal of Central South University》 SCIE EI CAS 2013年第8期2219-2225,共7页
Enhanced speech based on the traditional wavelet threshold function had auditory oscillation distortion and the low signal-to-noise ratio (SNR). In order to solve these problems, a new continuous differentiable thresh... Enhanced speech based on the traditional wavelet threshold function had auditory oscillation distortion and the low signal-to-noise ratio (SNR). In order to solve these problems, a new continuous differentiable threshold function for speech enhancement was presented. Firstly, the function adopted narrow threshold areas, preserved the smaller signal speech, and improved the speech quality; secondly, based on the properties of the continuous differentiable and non-fixed deviation, each area function was attained gradually by using the method of mathematical derivation. It ensured that enhanced speech was continuous and smooth; it removed the auditory oscillation distortion; finally, combined with the Bark wavelet packets, it further improved human auditory perception. Experimental results show that the segmental SNR and PESQ (perceptual evaluation of speech quality) of the enhanced speech using this method increase effectively, compared with the existing speech enhancement algorithms based on wavelet threshold. 展开更多
关键词 continuous differentiable wavelet threshold fimction speech enhancement Bark wavelet packet non-fixed deviation noise
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Dynamic programming methodology for multi-criteria group decision-making under ordinal preferences 被引量:3
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作者 Wu Li Guanqi Guo +1 位作者 Chaoyuan Yue Yong Zhao 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2010年第6期975-980,共6页
A method of minimizing rankings inconsistency is proposed for a decision-making problem with rankings of alternatives given by multiple decision makers according to multiple criteria. For each criteria, at first, the ... A method of minimizing rankings inconsistency is proposed for a decision-making problem with rankings of alternatives given by multiple decision makers according to multiple criteria. For each criteria, at first, the total inconsistency between the rankings of all alternatives for the group and the ones for every decision maker is defined after the decision maker weights in respect to the criteria are considered. Similarly, the total inconsistency between their final rankings for the group and the ones under every criteria is determined after the criteria weights are taken into account. Then two nonlinear integer programming models minimizing respectively the two total inconsistencies above are developed and then transformed to two dynamic programming models to obtain separately the rankings of all alternatives for the group with respect to each criteria and their final rankings. A supplier selection case illustrated the proposed method, and some discussions on the results verified its effectiveness. This work develops a new measurement of ordinal preferences’ inconsistency in multi-criteria group decision-making (MCGDM) and extends the cook-seiford social selection function to MCGDM considering weights of criteria and decision makers and can obtain unique ranking result. 展开更多
关键词 multi-criteria group decision-making (MCGDM) ordinal preference minimum deviation method dynamic programming Cook-Seiford social selection function.
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Numerical method of slope failure probability based on Bishop model 被引量:3
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作者 苏永华 赵明华 张月英 《Journal of Central South University of Technology》 EI 2008年第1期100-105,共6页
Based on Bishop's model and by applying the first and second order mean deviations method, an approximative solution method for the first and second order partial derivatives of functional function was deduced acc... Based on Bishop's model and by applying the first and second order mean deviations method, an approximative solution method for the first and second order partial derivatives of functional function was deduced according to numerical analysis theory. After complicated multi-independent variables implicit functional function was simplified to be a single independent variable implicit function and rule of calculating derivative for composite function was combined with principle of the mean deviations method, an approximative solution format of implicit functional function was established through Taylor expansion series and iterative solution approach of reliability degree index was given synchronously. An engineering example was analyzed by the method. The result shows its absolute error is only 0.78% as compared with accurate solution. 展开更多
关键词 Bishop mechanical model failure probability of slope mean deviation method implicit function Taylor series dump of open-pit
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Maximizing deviation method for multiple attribute decision making under q-rung orthopair fuzzy environment 被引量:2
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作者 Jie Wang Gui-wu Wei +1 位作者 Cun Wei Jiang Wu 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2020年第5期1073-1087,共15页
Because of the uncertainty and subjectivity of decision makers in the complex decision-making environment,the evaluation information of alternatives given by decision makers is often fuzzy and uncertain.As a generaliz... Because of the uncertainty and subjectivity of decision makers in the complex decision-making environment,the evaluation information of alternatives given by decision makers is often fuzzy and uncertain.As a generalization of intuitionistic fuzzy set(IFSs)and Pythagoras fuzzy set(PFSs),q-rung orthopair fuzzy set(q-ROFS)is more suitable for expressing fuzzy and uncertain information.But,in actual multiple attribute decision making(MADM)problems,the weights of DMs and attributes are always completely unknown or partly known,to date,the maximizing deviation method is a good tool to deal with such issues.Thus,combine the q-ROFS and conventional maximizing deviation method,we will study the maximizing deviation method under q-ROFSs and q-RIVOFSs in this paper.Firstly,we briefly introduce the basic concept of q-rung orthopair fuzzy sets(q-ROFSs)and q-rung interval-valued orthopair fuzzy sets(q-RIVOFSs).Then,combine the maximizing deviation method with q-rung orthopair fuzzy information,we establish two new decision making models.On this basis,the proposed models are applied to MADM problems with q-rung orthopair fuzzy information.Compared with existing methods,the effectiveness and superiority of the new model are analyzed.This method can effectively solve the MADM problem whose decision information is represented by q-rung orthopair fuzzy numbers(q-ROFNs)and whose attributes are incomplete. 展开更多
关键词 Multiple attribute decision making(MADM) q-rung orthopair fuzzy sets(q-ROFSs) q-rung interval-valued orthopair fuzzy sets (q-RIVOFSs) Maximizing deviation method Building materials
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Multi-attribute decision making model based on optimal membership and relative entropy 被引量:1
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作者 Rao Congjun Zhao Yong 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2009年第3期537-542,共6页
To study the problems of multi-attribute decision making in which the attribute values are given in the form of linguistic fuzzy numbers and the information of attribute weights are incomplete, a new multi-attribute d... To study the problems of multi-attribute decision making in which the attribute values are given in the form of linguistic fuzzy numbers and the information of attribute weights are incomplete, a new multi-attribute decision making model is presented based on the optimal membership and the relative entropy. Firstly, the definitions of the optimal membership and the relative entropy are given. Secondly, for all alternatives, a set of preference weight vectors are obtained by solving a set of linear programming models whose goals axe all to maximize the optimal membership. Thirdly, a relative entropy model is established to aggregate the preference weight vectors, thus an optimal weight vector is determined. Based on this optimal weight vector, the algorithm of deviation degree minimization is proposed to rank all the alternatives. Finally, a decision making example is given to demonstrate the feasibility and rationality of this new model. 展开更多
关键词 multi-attribute decision making optimal membership relative entropy deviation degree
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基于手持式激光测距仪的大尺寸测量应用研究 被引量:5
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作者 曲兴华 吴宏岩 戴建芳 张福民 Xing-hua Hong-yan Jian-fang Fu-min 《计量学报》 CSCD 北大核心 2009年第6期-,共4页
提出了一种基于手持式激光测距仪的大尺寸测量系统及方法.分别通过以手持式激光测距仪和增最式光电编码器为核心的测距及测角单元获得目标测量点的极坐标;再南运动控制器、驱动器、执行电机等构成的伺服控制系统,带动测距仪完成工件的... 提出了一种基于手持式激光测距仪的大尺寸测量系统及方法.分别通过以手持式激光测距仪和增最式光电编码器为核心的测距及测角单元获得目标测量点的极坐标;再南运动控制器、驱动器、执行电机等构成的伺服控制系统,带动测距仪完成工件的扫描测量;然后在极坐标系下利用最小二乘拟合法进行数据处理,并对一钢质圆环内径进行了测量,测量半径标准差为0.2mm.最后,研究了多站组合测量模式及坐标配准方法.Abstract:A large -scale measurement system based on a portable laser range finder is presented, which acquires the range and angle information by means of laser range finder and incremental photoelectric enceder. Under the control of servo system consisting of motion eontroller、driver and executive motor, the scanning measurement of the work-piece is implemented. Then, the data is processed using least squares fit and inner diameter measurement of steel circular ring was carried out, with the standard deviation of the radius 0. 2 mm. At last, the combined measurement and coordinate registration algorithm is studied. 展开更多
关键词 手持式激光测距仪 大尺寸测量 应用研究 Study laser range diameter MEASUREMENT standard deviation MEASUREMENT SYSTEM 最小二乘拟合法 least SQUARES 伺服控制系统 极坐标系 SERVO SYSTEM information 运动控制器 光电编码器 坐标配准 圆环内径 数据处理 扫描测量
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Application of deviation rate in oil and gas reservoir exploration 被引量:1
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作者 汤井田 张继锋 +1 位作者 冯兵 王烨 《Journal of Central South University of Technology》 EI 2008年第2期251-255,共5页
Three dimensional geophysical models were abstracted and established according to characteristics of oil and gas reservoir.Then direct current fields for different models were simulated with finite element software(fi... Three dimensional geophysical models were abstracted and established according to characteristics of oil and gas reservoir.Then direct current fields for different models were simulated with finite element software(finite element program generator) by hole-to-surface resistivity method.Numerical solution was compared with analytical one for the homogeneity earth model.And a new parameter of deviation rate was proposed by analyzing different plot curves.The results show that the relative error of solution for homogeneity earth model may attain to 0.043%.And deviation rate decreases from 18% to 1% and its anomaly range becomes wide gradually when the depth of oil and gas reservoir increases from 200 to 1 500 m.If resistivity ratio of oil and gas reservoir to sur-rounding rock decreases from 100 to 10 for the resistive oil and gas reservoir,the amplitude attenuation of deviation rate nearly reaches 8%.When there exists stratum above oil and gas reservoir,and influence of resistive stratum may be eliminated or weakened and anomaly of oil and gas reservoir can be strengthened. 展开更多
关键词 numerical simulation deviation rate oil and gas reservoir hole-to-surface resistivity method finite element programgenerator
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Selecting suitable key supplier for core components during smart complex equipment central-private enterprises collaborative development process:from two different forms of evaluation information and matching perspective 被引量:1
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作者 HUANG Xin QI Xiaoyan +1 位作者 CHEN Hongzhuan CAI Xiang 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2023年第4期939-954,共16页
With the development of central-private enterprises integration,selecting suitable key suppliers are able to provide core components for smart complex equipment.We consider selecting suitable key suppliers from matchi... With the development of central-private enterprises integration,selecting suitable key suppliers are able to provide core components for smart complex equipment.We consider selecting suitable key suppliers from matching perspective,for it not only satisfies natural development of smart complex equipment,it is also a good implementation of equipment project in central-private enterprises integration context.In in this paper,we carry out two parts of research,one is evaluation attributes based on comprehensive analysis,and the other is matching process between key suppliers and core components based on the matching attribute.In practical analysis process,we employ comprehensive evaluated analysis methods to acquire relevant attributes for the matching process that follows.In the analysis process,we adopt entropy-maximum deviation method(MDM)-decision-making trial and evaluation laboratory(DEMATEL)-technique for order preference by similarity to an ideal solution(TOPSIS)to obtain a comprehensive analysis.The entropy-MDM is applied to get weight value,DEMATEL is utilized to obtain internal relations,and TOPSIS is adopted to get ideal evaluated solution.We consider aggregating two types of evaluation information according to similarities of smart complex equipment based on the combination between geometric mean and arithmetic mean.Moreover,based on the aforementioned attributes and generalized power Heronian mean operator,we aggregate preference information to acquire relevant satisfaction degree,then combine the constructed matching model to get suitable key supplier.Through comprehensive analysis of selecting suitable suppliers,we know that two-sided matching and information aggregation can provide more research perspectives for smart complex equipment.Through analysis for relevant factors,we find that leading role and service level are also significant for the smart complex equipment development process. 展开更多
关键词 smart complex equipment key supplier entropymaximum deviation method(MDM) decision-making trial and evaluation laboratory(DEMATEL) technique for order preference by similarity to an ideal solution(TOPSIS) heronian mean operator central-private enterprises collaborative development
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Solving position-posture deviation problem of multi-legged walking robots with semi-round rigid feet by closed-loop control 被引量:1
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作者 陈刚 金波 陈鹰 《Journal of Central South University》 SCIE EI CAS 2014年第11期4133-4141,共9页
The semi-round rigid feet would cause position-posture deviation problem because the actual foothold position is hardly known due to the rolling effect of the semi-round rigid feet during the robot walking. The positi... The semi-round rigid feet would cause position-posture deviation problem because the actual foothold position is hardly known due to the rolling effect of the semi-round rigid feet during the robot walking. The position-posture deviation problem may harm to the stability and the harmony of the robot, or even makes the robot tip over and fail to walk forward. Focused on the position-posture deviation problem of multi-legged walking robots with semi-round rigid feet, a new method of position-posture closed-loop control is proposed to solve the position-posture deviation problem caused by semi-round rigid feet, based on the inverse velocity kinematics of the multi-legged walking robots. The position-posture closed-loop control is divided into two parts: the position closed-loop control and the posture closed-loop control. Thus, the position-posture control for the robot which is a tight coupling and nonlinear system is decoupled. Co-simulations of position-posture open-loop control and position-posture closed-loop control by MATLAB and ADAMS are implemented, respectively. The co-simulation results verify that the position-posture closed-loop control performs well in solving the position-posture deviation problem caused by semi-round rigid feet. 展开更多
关键词 position-posture deviation semi-round rigid feet closed-loop control multi-legged walking robots
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A New Shaping Model for Green Ceramic Balls
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作者 REN Cheng-zu, WU Zhen-yong, JIN Xin-ming, WANG Chun-jie, XU Qiang (Institute of Mechanical Engineering, Tianjin University, Tianjin 300072, China) 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 2002年第S1期35-36,共2页
The shaping quality of green ceramic balls is directly related to the efficiency and cost of later machining for the ceramic balls. Until now the shaping for green ceramic balls is still conducted by handwork. In this... The shaping quality of green ceramic balls is directly related to the efficiency and cost of later machining for the ceramic balls. Until now the shaping for green ceramic balls is still conducted by handwork. In this paper, a new shaping model for green ceramic balls was designed. In the new model, two grinding wheels with the same generator line as circular arc are mounted on symmetry, and their axes are parallel. The green ball can be put in the enveloping space formed by the two grinding wheels. The radius of generator line must be equal to or slightly greater than the final radius of the green balls, which can ensure that an ideal sphere can be enveloped by the generator of grinding wheel as grinding the green body surface with the wheels. One of the two wheels rotates in upward direction at high speed v 1, conversely, the other wheel rotates in downward direction at low speed v 2, and a cluster of compressed air is exerted on the green ball above for canceling out the force acting upon the green ball created by the action of the grinding wheel revolving at high speed and avoiding that the green ball jumps off its station. Because of the randomness of the distributions of abrasive grains on the surface of grinding wheels, the size and shape of the abrasive grains, and the posture of green body when falling into the grinding space, the values and directions of the resultant forces and torques exerted on the body, caused by the tow wheels, are random, the rotation of green body is irregular under the actions of the compressed air and the wheels. The irregularity of rotation can ensure an ideal sphere in theory. Experiment researches indicate that the new shaping model can improve the spherical deviations and the size distribution of the green ceramic balls, raise the production, and reduce the costs. The spherical deviations can be improved to 0.04 mm easily. It can be observed by SEM that there is no crack in the surface of sintered ceramic balls shaped with the new model in green blank. 展开更多
关键词 ceramic balls green SHAPING spherical deviation
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