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Semi-Closed Cube： An Effective Approach to Trading Off Data Cube Size and Query Response Time

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Journal of Computer Science & Technology 2005年第3期20卷 367-372页

作者： sheng-EnLi ShanWang DepartmentofComputerScienceandTechnology ShandongInstituteofArchitectureandEngineeringJinan250014P.R.China／／SchoolofInformationRenminUniversityBeijing100872P.R.China SchoolofInformation RenminUniversityBeijing100872P.R.China

The results of data cube will occupy huge amount of disk space when the base table is of a large number of attributes. A new type of data cube, compact data cube like condensed cube and quotient cube, was proposed to solve the problem. It compresses data cube dramatically. However, its query cost is so high that it cannot be used in most applications. This paper introduces the semi-closed cube to reduce the size of data cube and achieve almost the same query response time as the data cube does. Semi-closed cube is a generalization of condensed cube and quotient cube and is constructed from a quotient cube. When the query cost of quotient cube is higher than a given threshold, semi-closed cube selects some views and picks a fellow for each of them. All the tuples of those views are materialized except those closed by their fellows. To find a tuple of those views, users only need to scan the view and its fellow. Thus, their query performance is improved. Experiments were conducted using a real-world data set. The results show that semi-closed cube is an effective approach of data cube.

关键词： warehousing OLAP (on-line analytical processing) data cube

Hausdorff Dimensions of Quasilines and Differentiability of Quasisymmetric Homeomorphisms

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Acta Mathematica Sinica,English Series 2016年第4期32卷 499-506页

作者： sheng Jin HUO sheng Jian WU Department of Mathematics Tianjin Polytechnic University LMAM and School of Mathematical Sciences Peking University

In this paper,we try to describe the relationship between the differentiability of a quasisymmetric homeomorphism and the local Hausdorff dimension of the quasiline at a point.

关键词： Quasiline quasisymmetric Fuchsian group Mostow’s rigidity

Phase field simulation of single bubble behavior under an electric field

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Chinese Physics B 2018年第9期27卷 389-395页

作者： Chang-sheng Zhu Dan Han sheng Xu School of Computer and Communication Lanzhou University of Technology State Key Laboratory of Gansu Advanced Processing and Recycling of Non-Ferrous Metal Lanzhou University of Technology

Based on the Cahn-Hilliard phase field model, a three-dimensional multiple-field coupling model for simulating the motion characteristics of a rising bubble in a liquid is established in a gas-liquid two-phase flow. The gas-liquid interface motion is simulated by using a phase-field method, and the effect of the electric field intensity on bubble dynamics is studied without electric field, or with vertical electric field or horizontal electric field. Through the coupling effect of electric field and flow field, the deformation of a single rising bubble and the formation of wake vortices under the action of gravity and electric field force are studied in detail. The correctness of the results is verified by mass conservation, and the influences of different electric field directions and different voltages on the movement of bubbles in liquid are considered. The results show that the ratio of the length to axis is proportional to the strength of the electric field when the air bubble is stretched into an ellipsoid along the electric field line under the action of electrostatic gravity and surface tension. In addition, the bubble rising speed is affected by the electric field, the vertical electric field accelerates the bubble rise, and the horizontal direction slows it down.

关键词： electro-hydro dynamics numerical simulation phase field method bubble

New Soliton-like Solutions to Variable Coefficients MKdV Equation

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Communications in Theoretical Physics 2004年第5X期42卷 649-654页

作者： LIDe-sheng YUZhen-sheng ZHANGHong-Qing DepartmentofMathematics ShenyangNormalUniversityShenyang110034China CollegeofScience UniversityofShanghaiforScienceandTechnologyShanghai200093China DepartmentofAppliedMathematics DalianUniversityofTechnologyDalian116024China

A further improved projective Riccati equation method is proposed. By applying it to solve the variable coefficients MKdV equation, we obtain many new-type soliton-like solutions to this equation.

关键词：孤波解变量系数法 MKdV 投影方程非线性偏微分

Experimental and numerical investigations of the mechanical behavior of half sandwich laminate in the context of blanking

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Advances in Manufacturing 2020年第2期8卷 177-188页

作者： sheng Cai Lin Chen Department of V ehicle Engineering College of EngineeringChina Agricultural UniversityBeijing 100083People's Republic of China CW Bearing GmbH Hamburg 22113Germany

In this study,the complex mechanical behavior of an aluminum/low-density polyethylene(LDPE)half sandwich structure was investigated during the blanking *** tests were conducted for the polymer and metal layer and the delamination behavior of the adhesive between the two layers.A new testing device was designed for detecting the delamination under tensile *** finite element models were established for the mechanical tests of the metal layer and the delamination of both layers for inverse parameter *** parameters for Lemaitre-type damage,Drucker-Prager,and cohesive zone modeIs were identified for the metal,polymer,and adhesive,respectively.A finiteelement(FE)model was established for the blanking process of the sandwich *** experimental forcedisplacement curves,obtained in the blanking process of the half sandwich sheet,were compared with the predicted results of the FE *** results showed that the predicted force-displacement curves and the experimental results were in good ***,the correlation between cutting clearance and changes in the forcedisplacement curves was *** feature values quantitatively described the imperfection of the experimental cutting *** effect of punch clearance on these values was studied numerically and *** results indicated that a smaller clearance generated a better cutting-edge *** stress state of the half sandwich structure during blanking was analyzed using the established FE model.

关键词： Sandwich plates Blanking Continuum damage mechanics(CDM) Drucker-Prager model Cohesive zone model

New Second-order Contingent Epiderivatives and Set-valued Optimization Problems

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Acta Mathematicae Applicatae Sinica 2016年第4期32卷 983-994页

作者： sheng-kun ZHU sheng-jie LI College of Economic Mathematics Southwestern University of Finance and Economics College of Mathematics and Statistics Chongqing University

In this paper, we introduce the concept of second-order compound contingent epiderivative for set-valued maps and discuss its relationship to the second-order contingent epiderivative. Simultaneously, we also investigate some special properties of the second-order compound contingent epiderivative. By virtue of the second-order compound contingent epiderivative, we establish some unified second-order sufficient and necessary optimality conditions for set-valued optimization problems. All results in this paper generalize the corresponding results in the literature.

关键词： set-valued optimization second-order compound contingent epiderivative optimality conditions

A novel method for radar echo simulation based on fast-constructed database

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Journal of Systems Engineering and Electronics 2022年第1期33卷 72-79页

作者： HUANG Xiaowei sheng Xinqing Institute of Radio Frequency Technology and Software School of Integrated Circuits and ElectronicsBeijing Institute of TechnologyBeijing 100081China

This paper presents a novel method for fast calculation of radar echo in near-field regions after the equivalent source has been computed by method of moments(MoM).An easy-to-access near-field database(NFDB)is established,which is built on the auxiliary tetrahedral meshes surrounding the nearfield regions of *** near-fields calculation(NFC)of arbitrary observation points can be expressed explicitly via the *** efficient matrix compression scheme named random sampling-based butterfly factorization(RS-BF)is proposed to speed up the construction of *** this approach,each group of O(N)elements in the database can be calculated through one fast matrix-vector multiplication operation that has a computational complexity below O(Nlog~2 N).The proposed method can avoid time-consuming point-by-point NFC of the traditional *** numerical examples are presented to demonstrate the accuracy and efficiency of this *** particular,the echo simulation of a missile-target encounter example is presented to illustrate its capability for practical applications.

关键词： radar echo simulation near-field database(NFDB) butterfly factorization(BF)

Parameter identification and blanking simulations of DP1000 and Al6082-T6 using Lemaitre damage model

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Advances in Manufacturing 2021年第3期9卷 457-472页

作者： sheng Cai Lin Chen Department of Vehicle Engineering College of EngineeringChina Agricultural UniversityBeijing100083People’s Republic of China CW Bearing GmbH 22113HamburgGermany

This work provides numerical and experimental investigations of blanking process,where the shear-enhanced Lemaitre’s damage model is fully characterized and successfully applied in blanking process to predict the cutting force and cutting edge geometry under different blanking process *** high strength steel DP1000 and an aluminum alloy Al6082-T6 are selected for series of *** obtain the damage parameters in Lemaitre’s damage model the flat rectangular notched specimens tensile test was conducted and the inverse parameter identification procedure was *** characterizing the crack closure parameter h in the shear enhanced Lemaitre’s damage model,an in-plane torsion test with novel specimen design was *** finite element model(FEM)of this test was established with the minimum mesh size of 0.01 mm which was consistent with the minimum mesh size in the shear zone of the FEM for blanking process *** longitudinal strain distributions of four kinds of initial notch radius or central-hole specimen were measured and compared with simulation results to validate the FEMs for these four *** analysis of blanking of a circular work piece also was performed under three *** effects of blanking conditions on sheared part morphology were *** triaxiality distribution of the blank sheet was revealed taking advantage of the successfully established *** availability of the testing method and the determination method of the parameters was investigated.

关键词： Blanking Lemaitre damage model Stress triaxiality Finite element model(FEM)

A study of a supersonic capsule/rigid disk-gap-band parachute system using large-eddy simulation

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Applied Mathematics and Mechanics(English Edition) 2021年第4期42卷 485-500页

作者： sheng GONG Chuijie WU School of Aeronautics and Astronautics Dalian University of TechnologyDalian 116024Liaoning ProvinceChina

The aerodynamic performances and flow features of the capsule/rigid disk-gap-band(DGB)parachute system from the Mach number 1.8 to 2.2 are *** use the adaptive mesh refinement(AMR),the hybrid tuned center-difference and weighted essentially non-oscillatory(TCD-WENO)scheme,and the large-eddy simulation(LES)with the stretched-vortex subgrid *** simulations reproduce complex interaction of the flow structures,including turbulent wakes and bow shocks,as well as bow shocks and expansion *** results show that the calculated aerodynamic drag coefficient agrees well with the previou *** the aerodynamic drag coefficient and the aerodynamic drag oscillation of the parachute system decrease with the increase of the initial Mach number of the *** is found that the position and angle of the bow shock ahead of the canopy change as the Mach number increases,which makes the flow inside the canopy and the turbulent wake behind the canopy more complex and unstable.

关键词： compressible flow adaptive mesh refinement(AMR) large-eddy simulation(LES) supersonic flow rigid disk-gap-band(DGB)parachute