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CONVERGENCE OF CASCADE ALGORITHMS AND SMOOTHNESS OF REFINABLE DISTRIBUTIONS

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Chinese Annals of Mathematics,Series B 2003年第3期24卷 367-386页

作者： SUN QIYU Department of Mathematics, university of Houston, Houston, TX 77204, USA. Department of Mathematics, national university of singapore, 10 kent ridge crescent, {{3., singapore. Department of Mathematics University of Houston TX 77204 USA Department of Mathematics National University of Singapore 10 Kent Ridge Crescent 119260 Singapore

In this paper, the author at first develops a method to study convergence of the cascadealgorithm in a Banach space without stable assumption on the initial (see Theorem 2.1), andthen applies the previous result on the convergence to characterizing compactly supportedrefinable distributions in fractional Sobolev spaces and Holder continuous spaces (see Theorems3.1, 3.3. and 3.4). Finally the author applies the above characterization to choosing appropriateinitial to guarantee the convergence of the cascade algorithm (see Theorem 4.2).

关键词： Cascade algorithm Cascade operator Refinable distribution Shift-invariant space Linear independent shifts Stable shifts Fractional Sobolev space

A THIRD-ORDER BOUSSINESQ MODEL APPLIED TO NONLINEAR EVOLUTION OF SHALLOW-WATER WAVES

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Journal of Hydrodynamics 2000年第2期12卷 107-126页

作者： Zhang Ying long CCM MINDEF, Department of Mech. and Prod. Eng., national university of singapore, 10 kent ridge crescent, singapore 119260 Zhu Song ping Department of Mathematics, the {{3. of Wollongong, Wollongong, NSW 2522, Australia Natl Univ of singapore Singapore Singapore

The conventional Boussinesq model is extended to the third order in dispersion and nonlinearity. The new equations are shown to possess better linear dispersion characteristics. For the evolution of periodic waves over a constant depth, the computed wave envelops are spatially aperiodic and skew. The model is then applied to the study of wave focusing by a topographical lens and the results are compared with Whalin′s (1971) experimental data as well as some previous results from the conventional Boussinesq model. Encouragingly, improved agreement with Whalin′s experimental data is found. [WT5”HZ]

关键词： shallow water waves nonlinearity evolution third order Boussinesq model

Comparing the Effectiveness of Coatings on Carbide andCermet Cutting Tool Inserts

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Journal of Materials Science & Technology 1995年第4期11卷 269-275页

作者： K.H. W.Seah M.Rahman and C.H.Lee (Dept. of Mech. & Prod. Eng., national university of singapore, 10 kent ridge crescent, singapore 0511 T.N.Goh (Dept. of Ind. & Sys. Eng., national university of singapore, 10 kent ridge crescent, singapore 0511) national Univ of singapore Singapore

A series of metal cutting experiments was performed on a CNC lathe to evaluate the performance of various coatings on different tool substrates. The workpiece material was plain medium carbon steel and the cutting tool materials were carbide and cermet inserts coated with various single as well as multilayer coatings. Machining was done under various cutting conditions of speed and feed-rate, and for various durations of Cutting. The output parameters studied were the cutting forces (axial, radial and tangential), the surface roughness of the workpiece, as well as the tool wear (crater and flank wear). From these results, the performances of the various cutting inserts are evaluated and compared. Results show that cutting forces are significantly lower when using coated cermets than when using coated carbides although different coatings on the same substrate also result in different cutting forces. However, there is less difference in the surface roughness of the finished workpiece for the various coatings and substrates.

关键词： Tool Comparing the Effectiveness of Coatings on Carbide andCermet Cutting Tool Inserts

Formation, Structure and Properties of Bulk Metallic Glasses

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Journal of Materials Science & Technology 1999年第2期15卷 97-110页

作者： Y. Li(Department of Materials Science, Faculty of Science, national university of singapore, Lower kent ridge Road,{{3. 119260 E-mail:masliy@nus.edu.sg) Department of Materials Science Faculty of Science National University of Singapore Lower Kent Ridge Road Singapore 119260 Singapore

Bulk metallic glasses with up to 72 mm critical section thickness have been obtained by conventional casting techniques and the properties of these materials, particularly the mechanical and magnetic properties have been studied. These materials have been demonstrated to have novel properties which are fundamentally different from their crystalline counterparts. The recent status of research and development in formation, structure and properties of bulk metallic glasses is reviewed. The techniques to produce such bulk glasses are summarized and the glass forming ability and the critical cooling rate of these materials are discussed. Further consideration of the development and application of this new class of materiaIs will be proposed.

关键词： Ni Zr Structure and Properties of Bulk Metallic Glasses Formation OK Cu Figure

Experimental and discrete element numerical analysis of side slope instability induced by fissure water underlying impervious bed

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Science China(Technological Sciences) 2005年第Z1期48卷 65-80页

作者： LIU Bingshan1, LI Shihai1, ZHANG Lei1,2 & WANG Jianguo3.. Institute of Mechanics, Chinese Academy of Sciences, Beijing 100080, China 2. Graduate School, Chinese Academy of Sciences, Beijing 100060, China 3. Tropical Marine Science Institute, national university of singapore,{3., singapore 119260 Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China Graduate School Chinese Academy of Sciences Beijing 100060 China Tropical Marine Science Institute National University of Singapore 10 Kent Ridge Crescent Singapore 119260 Singapore

When the sliding mass contains impervious bed, rainfall can infiltrate into mountain via crevices and form higher artesian aquifer at impervious bed inferior. This will decrease slip resistance and increase sliding forces of the sliding mass, thus lowering the safety factor, and inducing landslide disasters. In this paper, a landslide experimental apparatus is designed for experimental studies on the mechanism of this type of landslides. Meanwhile, the non-dimensional parameters in the model experiment are taken into account using dimensional analysis. The experimental results show that (1) the ratio of the cleft water pressure to the overlying pressure is a crucial parameter affecting the stability of the slope; (2) when the shut-in pressure reaches 80% of the normal component of the pressure on the slip surface made up of rock and soil, landslide will occur; (3. the whole slope will start to slide when the shut-in pressure is equal to the normal component of the pressure formed by the overlying rock and soil on the upper 3.% area. In this article, a discrete element method simulation is used to investigate the influence of cleft water pressure and shearing strength on the landslide stability. It can be concluded that the critical value of Ccr, ?cr, which determines the slide mass stability, increases with the increase of the water pressure; if the water pressure reaches a high level, the stability of the slide mass depends mainly on C, while the influence of ? becomes smaller than C.

关键词： impervious bed, rainfall infiltration, pore water pressure, landslide experiment, displacement monitor, discrete element method.

Stochastic structural model of rock and soil aggregates by continuum-based discrete element method

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Science China(Technological Sciences) 2005年第Z1期48卷 95-106页

作者： WANG Yuannian1, ZHAO Manhong1, LI Shihai1 & J.G. Wang21. Institute of Mechanics, Chinese Academy of Sciences, Beijing 100080, China 2. Tropical Marine Science Institute, national university of singapore, 10 kent ridge crescent, singapore 119260 Institute of Mechanics Chinese Academy of Sciences Beijing China Tröpical Marine Science Institute National University of Singapore Singapore

This paper first presents a stochastic structural model to describe the random geometrical features of rock and soil aggregates. The stochastic structural model uses mixture ratio, rock size and rock shape to construct the microstructures of aggregates, and introduces two types of structural elements (block element and jointed element) and three types of material elements (rock element, soil element, and weaker jointed element) for this microstructure. Then, continuum-based discrete element method is used to study the deformation and failure mechanism of rock and soil aggregate through a series of loading tests. It is found that the stress-strain curve of rock and soil aggregates is nonlinear, and the failure is usually initialized from weaker jointed elements. Finally, some factors such as mixture ratio, rock size and rock shape are studied in detail. The numerical results are in good agreement with in situ test. Therefore, current model is effective for simulating the mechanical behaviors of rock and soil aggregates.

关键词： CDEM, rock and soil aggregate, mixture ratio.

LINEAR INDEPENDENCE OF THE INTEGER TRANS-LATES OF COMPACTLY SUPPORTED DISTRIBU-TIONS AND REFINABLE VECTORS

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Applied Mathematics(A Journal of Chinese Universities) 2001年第4期16卷 381-396页

作者： Sun QiyuDept. of Math.,national university of singapore,10 {{3. ridge crescent,singapore 119260,singapore. Dept. of Math. National University of Singapore Singapore Singapore

In this paper,the global and local linear independence of any compactly supported distributions by using time domain spaces,and of refinable vectors by invariant linear spaces are investigated.

关键词： Global linear independence local linear independence refinable vector invariant space.

Hardness, Wear Resistance and Fracture Toughness of Cast Hiduminium/Corundum Particulate Composites

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Journal of Materials Science & Technology 1996年第5期12卷 357-360页

作者： K.H.W.Seah(Dept. of Mechanical Engineering, national university of singapore, 10 kent ridge crescent, singapore 119260)R.S.Kulkarni and S.C.Sharma (Dept. of Mechanical Engineering, R.V.College of Engineering, Mysore Road, Bangalore-560-059, Karnataka, Ind Dept. of Mechanical Engineering National University of Singapore 10 Kent Ridge Crescent Singapore 119260 Singapore Dept. of Mechanical Engineering R.V.College of Engineering Mysore Road Bangalore-560-059 Karnataka India Dept. of Mechanical Engineering SJCE Mysore India

This paper reports some results obtained in an investigation to see how increasing the corundum dispersoid content from 0% to 7% in a matrix of as-cast and wrought hiduminium alloy affects the hardness. wear resistance and fracture toughness of the composite. The results show that as the corundum content is increased, the hardness and the wear resistance increase remarkably,whereas the fracture toughness drops significantly. It was found that Just a minute amount of corundum is sufficient to cause a fairly large change in these mechanical properties. The hardness of the material is also affected signifIcantly by the aging time. Moreover, if other factors are kept constant, hot extrusion improves both its hardness and its wear resistance. whereas the fracture toughness is decreased

关键词： Wear Resistance and Fracture Toughness of Cast Hiduminium/Corundum Particulate Composites Book Cast Hardness

JOHN *** AND HIS PUBLICATIONS

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Computer Aided Drafting,Design and Manufacturing 1996年第2期6卷 90-96页

作者： Qu Ruibin(Department of Mathemalics national university of singapore 10 kent ridge crescent singapore.{{3.)

John ***,one of the well-known English mathematician in the area of CAD/CAM and Computer Aided Geometric Design,passed away suddenly in March 1993.at the age of *** research work and publications of John *** are summa... 详细信息

关键词： ss:memorial article publications of J.A.Gregory