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Nuclear Science and Techniques 2021年第8期32卷 95-109页

作者： Ming dai Mao-Song Cheng Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China CAS Innovative Academies in TMSR Energy System Chinese Academy of SciencesShanghai 201800China

The algebraic collapsing acceleration(ACA)technique maximizes the use of geometric flexibility of the method of characteristics(MOC).The spatial grids for loworder ACA are the same as the high-order transport,which makes the numerical solution of ACA equations costly,especially for large-size *** speed-up the MOC transport iterations effectively for general geometry,a coarse-mesh ACA method that involves selectively merging fine-mesh cells with identical materials,called material-mesh ACA(MMACA),is *** energy group batching(EGB)strategy in the tracing process is proposed to increase the parallel efficiency for microscopic crosssection *** and macroscopic crosssection benchmark problems are used to validate and analyse the accuracy and efficiency of the MMACA *** maximum errors in the multiplication factor and pin power distributions are from the VERA-4 B-2 D case with silver-indium-cadmium(AIC)control rods inserted and are 104 pcm and 1.97%,*** with the single-thread ACA solution,the maximum speed-up ratio reached 25 on 12 CPU cores for microscopic cross-section VERA-4-2 D *** the C5 G7-2 D and LRA-2 D benchmarks,the MMACA method can reduce the computation time by approximately one *** present work proposes the MMACA method and demonstrates its ability to effectively accelerate MOC transport iterations.

关键词： Algebraic collapsing acceleration Material-mesh ACA Method of characteristics OpenMP Arbitrary geometry

Orientation angle workspaces of planar serial three-link manipulators

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Science China(Technological Sciences) 2009年第4期52卷 975-985页

作者： dai Jian S Department of Mechanical Engineering King’s College London University of LondonWC2R 2LS United Kingdom

This paper presents a classification on the workspaces of planar serial three-link manipulators, that is, position workspace and orientation angle workspace. Position workspace indicates the region reached by the reference point on the end-effector. Orientation angle workspace indicates a set of angle ranges by which the end-effector can reach with certain orientation for every point in the reachable position workspace. By introducing a virtual equivalent mechanism, reachable position workspace can be di- vided into several Grashof intervals and non-Grashof intervals. The calculation equations of orientation angle workspace are deduced in three situations according to the relationships among four link lengths in the virtual four-bar chain. Three examples are given for three kinds of relationship of link lengths. The orientation angle workspace of extended groups, that is, two of the three link lengths equal, and the orientation angle workspace when the reference point on the end-effector moves along a non-radial direction are also discussed. A program is developed to calculate orientation angle workspaces and output variation curves of orientation angle workspace and key data within the position workspace. The approach and program in this paper can be used for fast calculation and identification of the variation rule of the orientation angle workspace of any given planar serial three-link manipulator on the basis of its link parameters, and for the design of a highly dexterous serial manipulator with proposed link rela- tions.

关键词： planar serial manipulator orientation angle workspace virtual equivalent mechanism Grashof criterion

State of the art of lightweight aggregates used in lightweight refractories for working lining of high-temperature furnaces

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Journal of Iron and Steel Research International 2024年第6期31卷 1320-1343页

作者： Wei Zhang Wen-yong dai Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016LiaoningChina Research and Development Department AGC Plibrico(Dalian)Industries Inc.Dalian 116600LiaoningChina

Lightweight refractories for the working lining of high-temperature furnaces play an important role in the smelting of advanced steels and *** prepare lightweight refractories for the working lining of high-temperature furnaces,the synthesis of lightweight aggregates is the ***,the research on the synthesis of lightweight aggregates with high service temperature,low thermal conductivity,high strength,and good slag resistance has received widespread *** available literature on the synthesis of lightweight aggregates was summarized,including corundum,mullite,mullite-corundum,spinel,corundum-spinel,cordierite,cordierite-mullite,calcium hexaluminate,corundum-calcium hexaluminate,bauxite,magnesia,magnesia-based,and forsterite-based ***,the future development trend of lightweight aggregates was proposed.

关键词： Lightweight aggregate Lightweight refractory Working lining Apparent porosity Closed porosity Thermal conductivity Pore-forming approach

Fourier Method for an Over-Determined Elliptic System with Several Complex Variables

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Acta Mathematica Sinica,English Series 2006年第1期22卷 87-94页

作者： Dao Qing dai Department of Mathematics Sun Yat-Sen( Zhongshan) University Guangzhou 510275 P. R. China

Two boundary value problems are investigated for an over-determined elliptic system with several complex variables in polydisc. Necessary and sufficient conditions for the existence of finitely many linearly independent solutions and finitely many solvability conditions are derived. Moreover, the boundary value problem for any number of complex variables is treated in a unified way and the essential difference between the case of one complex variable and that of several complex variables is revealed.

关键词： Several complex variables Analytic functions Riemann problem Riemann Hilbert problem Over-determined elliptic system

Convergence in Law to Operator Fractional Brownian Motion of Riemann-Liouville Type

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Acta Mathematica Sinica,English Series 2013年第4期29卷 777-788页

作者： Hong Shuai dai School of Mathematics and Information Sciences Guangxi University

In this paper, we extend the well-studied fractional Brownian motion of Riemann-Liouville type to the multivariate case, and the corresponding processes are called operator fractional Brownian motions of Riemann-Liouville type. We also provide two results on approximation to operator fractional Brownian motions of Riemann-Liouville type. The first approximation is based on a Poisson process, and the second one is based on a sequence of I.I.D. random variables.

关键词： Operator fractional Brownian motion of Riemann-Liouville type Poisson process a se-quence of I.I.D. random variables weak convergence

Intersections of Homogeneous Cantor Sets with Their Translations

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Acta Mathematica Sinica,English Series 2008年第8期24卷 1313-1318页

作者： Mei Feng dai Nonlinear Scientific Research Center Faculty of Science Jiangsu University Zhenjiang 212013 P. R. China

We pursue the study on homogeneous Cantor sets with their translations. We get the fractal structure of intersection I（t）, and find that the Hausdorff measure of these sets forms a discrete spectrum whose non-zero values come only from shifting numbers with the coding of t. Concretely, a very brief calculation formula of the measure with the coding of t is given.

关键词： homogeneous Cantor set intersection fractal structure discrete spectrum

The Density of Linear Symplectic Cocycles with Simple Lyapunov Spectrum in YIC（X, SL（2, R））

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Acta Mathematica Sinica,English Series 2006年第1期22卷 301-310页

作者： Xiong Ping dai Department of Mathematics Nanjing University Nanjing 210093 P. R. China

Let （X, G（X）, m） be a probability space with a-algebra G（X） and probability measure m. The set V in G is called P-admissible, provided that for any positive integer n and positive-measure set Vn∈ contained in V, there exists a Zn∈G such that Zn belong to Vn and 0 〈 m（Zn）〈 1/n. Let T be an ergodic automorphism of （X, G） preserving m, and A belong to the space of linear measurable symplectic cocycles

关键词： Lyapunov spectrum Linear cocycle Nonuniform hyperbolicity

STABILITY OF ε-ISOMETRIES ON L_∞-SPACES

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Acta Mathematica Scientia 2019年第6期39卷 1733-1742页

作者： Duanxu dai College of Mathematics and Computer Science Quanzhou Normal UniversityQuanzhou 362000China

In this article,we discuss the stability ofε-isometries for L∞,λ-***,we first study the relationship among separably injectivity,injectivity,cardinality injectivity and universally left stability of L∞,λ-spaces as well as we show that the second duals of universally left-stable spaces are injective,which gives a partial answer to a question of Bao-Cheng-Cheng-dai,and then we prove a sharpen quantitative and generalized Sobczyk theorem which gives examples of nonseparable L∞-spaces X(but not injective)such that the couple(X,Y)is stable for every separable space *** gives a new positive answer to Qian's problem.

关键词： stability ε-isometry L∞-space

Combustion Characteristics of Coal Mine Methane in a Preheated-Burner Packed with Raschig Rings

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Journal of Thermal Science 2021年第5期30卷 1741-1750页

作者： dai Huaming ZHU Huiwei YANG Pan dai Hongchao HE Song WANG Zhiqiang School of Safety Science and Emergency Management Wuhan University of TechnologyWuhan430070China

The utilization of coal mine methane(CMM)through porous medium combustion(PMC)contributes to energy saving and environmental *** this paper,a double-layer porous medium burner with the combination of heat exchangers was designed to recycle the exhausted heat for preheating the inlet *** effects of Raschig ring sizes on the temperature distributions and pollutant emissions were studied under different operating *** results indicate that the preheating of inlet gas greatly influenced the temperature distribution and the optimum preheating effect was shown in the burner of spiral heat exchanger together with lower pollutant *** the increasing of inlet velocity and equivalence ratio,the peak temperature was increased *** the Raschig ring size increased,the flame temperature increased first and then decreased ***,the highest temperature and lowest average emissions of NOx and CO appeared in the burner of 10 mm Raschig *** study will provide the CMM utilization engineering with the theoretical foundation on PMC.

关键词： coal mine methane Raschig rings heat exchanger emissions preheating effect

Trot Gait with Twisting Trunk of a Metamorphic Quadruped Robot

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Journal of Bionic Engineering 2018年第6期15卷 971-981页

作者： Chunsong Zhang Jiansheng dai International Centre for Advanced Mechanisms and Robotics School of Meehanical Engineering Tianjin University Tianjin 300345 China Centre for Robotics Research King's College London Strand London UK

This paper proposes a metamorphic quadruped robot with a moveable trunk, called Origaker I. From the angle view of bionics, the robot can imitate the natural quadrupeds to twist its trunk. As we all know, most natural quadrupeds twist their trunk when running. The twisting trunk must bring significant benefits to their locomotion. Nevertheless there are few researches focusing on running gaits with twisting trunk of quadruped robots. Therefore, this paper investigates the trot gait with twisting trunk. One gait cycle of a lizard with twisting trunk is observed. Apart from the observation, the gait is designed based on the Zero Moment Point （ZMP） method and by con- sidering three points related to the twisting trunk. A simulation and an experiment are carried out to verify the efficiency of the trot gait with twisting trunk. It is found that the twisting trunk helps the quadruped robot get larger stride length and further perform higher lo- comotion speed than that with rigid trunk.

关键词： bionics quadruped robots twisting trunk trot gait