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Gradient estimates for the Heat Kernels in Higher Dimensional Heisenberg Groups

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Chinese Annals of Mathematics,Series B 2010年第3期31卷 305-314页

作者： Bin QIAN department of Mathematics and Statistics, Changshu Institute of Technology, Changshu 215500, Jiangsu, China Institut de Math′ematiques de Toulouse, Universit′e de Toulouse, CNRS 5219, France. department of Mathematics and Statistics Changshu Institute of Technology Changshu 215500 Jiangsu China Institut de Mathématiques de Toulouse Université de Toulouse CNRS 5219 France

The author obtains sharp gradient estimates for the heat kernels in two kinds of higher dimensional Heisenberg groups -- the non-isotropic Heisenberg group and the Heisenberg type group Hn,m. The method used here relies on the positive property of the Bakry-emery curvature F2 on the radial functions and some associated semigroup technics.

关键词： Gradient estimates Г2 curvature Heat kernels Sublaplace Heisenberg group

Hybrid silicon modulators

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Chinese Optics Letters 2009年第4期7卷 280-285页

作者： J.e.Bowers department of electrical and Computer engineering University of California Santa Barbara

A number of active elements have been demonstrated using the hybrid silicon evanescent platform, including lasers, amplifiers, and detectors. In this letter, two types of hybrid silicon modulators, flflfilling the building blocks in optical communication on this platform, are presented. A hybrid silicon electroabsorp- tion modulator, suitable for high speed interconnects, with 10-dB extinction ratio at -5 V and 16-GHz modulation bandwidth is demonstrated. In addition, a hybrid silicon Mach-Zehnder modulator utilizing carrier depletion in multiple quantum wells is proved with 2 *** voltage-length product, 150-nm optical bandwidth, and a large signal modulation up to 10 Gb/s.

关键词： Bandwidth electroabsorption modulators Modulation Modulators Optical communication Quantum well lasers Semiconducting indium compounds Semiconductor quantum wells Silicon Silicon detectors

Investigations of the Sheath effect on the Resultant Magnetic Field of a Cylindrical Monopole Plasma Antenna

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Plasma Science and Technology 2015年第2期17卷 153-158页

作者： Moses e.eMeTeRe department of Physics Covenant University Canaan Land

The functionality of the plasma antenna has been narrowed to types and brand names only. The physics of its operation has been neglected and has stagnated technological innovations. The magnetic field in the sheath and plasma were investigated. Notable specifications were worked out in the proposed improved cylindrical monopole plasma antenna. The occurrence of femto spin demagnetization was discovered between the duration of switch on and switch off of the antenna. This phenomenon seems transient because magnetization is highest at the switch on/off point.

关键词： cylindrical monopole plasma antenna magnetic field size Schr6dinger spin

Optical properties of Weyl semimetals

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National Science Review 2019年第2期6卷 206-208页

作者： Joel e.Moore department of Physics University of California Materials Science Division Lawrence Berkeley National Laboratory

The behavior of electrons in ordinary metals is dominated by physics near the Fermi surface. Indeed, many of the first successes of the quantum theory of solids, such as understanding the large specific heat of metals, followed from applications of the Fermi surface concept. Great effort has been devoted in recent years to semimetals in which the Fermi surface shrinks to a set of Dirac or Weyl points, where four

关键词： As Ta Optical properties of Weyl semimetals

experiments and modeling of discharge characteristics in water-mist sprays generated by pressure-swirl atomizers

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Journal of Thermal Science 2012年第6期21卷 539-548页

作者： Paolo e.Santangelo department of Fire Protection engineering University of Maryland3106 J.M.Patterson BuildingCollege ParkMD 20742USA

Pressure-swirl atomizers are often employed to generate a water-mist spray,typically employed in fire *** the present study,an experimental characterization of dispersion(velocity and cone angle)and atomization(drop-size axial evolution)was carried out following a previously developed methodology,with specific reference to the initial region of the ***-based techniques were used to quantitatively evaluate the considered phenomena:velocity field was reconstructed through a Particle Image Velocimetry analysis;drop-size distribution was measured by a Malvern Spraytec device,highlighting secondary atomization and subsequent coalescence along the spray ***,a comprehensive set of relations was validated as predictive of the involved parameters,following an inviscid-fluid *** proposed model pertains to early studies on pressure-swirl atomizers and primarily yields to determine both initial velocity and cone *** spray thickness is also predicted and a classic correlation for Sauter Mean Diameter is shown to provide good agreement with experimental *** analysis was carried out at the operative pressure of 80 bar;two injectors were employed featuring different orifice diameters and flow numbers,as a sort of parametric approach to this spray typology.

关键词： Water mist Pressure-swirl atomizers Atomization Velocity Cone angle

environmental chemical study on the marsh of Fatimid cemetery at Aswan City, egypt

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Journal of environmental Sciences 2002年第4期14卷 464-473页

作者： M.e.Soltan Chemistry department Faculty of Science

environmental chemical study were carried out on the Fatimid cemetery marsh at Aswan City(24°1'N and 32°9'e), egypt. Marsh contents(warter, soil, sediment, metal and nonmetal bearing salts, and emergent weed) were analysed to known the source of marsh water, speciation of the different elements between the marsh contents, and the toleration of emergent weed (Phargmites australies) for different metals and their bioaccumulation coefficients. Thus, metals(Ca, Mg, Na, K, Ni, Fe, Mn, Cu, Zn, Cd and Pb) and nonmetals(CO 2- 3, HCO - 3, Cl -, SO 2- 4, PO 3- 4, NO - 3, SiO 2, organic matter and pH value) were determined in the samples. According to the chemical analysis, and applying the base exchange equation(water type) and calculate the hydrochemical parameters for marsh water samples, we can indicate that the marsh water is ground water with Na SO 4 type and deep meteoric genesis. Topsoil of marsh dry land characterized by CaCl as dominant salt,while NaCl is a dominant salt in subsoil. The elevated pH values of marsh contents minimized the metal solubilities in different samples. Phragmites australies showed a strong ability to accumulate Mn and Fe in the aerial part in opposite to Co, Ni and Cd.

关键词： marsh water soil sediment emergent weed egypt

Seven possible states of geospatial data with respect to map projection and definition: a novel pedagogical device for GIS education

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Geo-Spatial Information Science 2018年第4期21卷 288-293页

作者： Steven e.Greco department of Human ecology University of CaliforniaDavisCAUSA

Conceptually,the theory and implementation of“map projection”in geographic information system(GIS)technology is difficult to comprehend for most introductory students and novice *** this difficulty is the concept of a“map projection file”that defines map projection parameters of geo-spatial *** problem of the“missing projection file”appears ubiquitous for all users,especially in practice where data is widely *** common problem is inadvertent misapplication of the“define Projection”tool that can result in a GIS dataset with an incorrectly defined map projection *** education should provide more guidance in differentiating the concepts of map projection versus projection files by increasing understanding and minimizing common errors.A novel pedagogical device is introduced in this paper:the seven possible states of GIS data with respect to map projection and *** seven possible states are:(1)a projected coordinate system(PCS)that is correctly defined,(2)a PCS that is incorrectly defined,(3)a PCS that is undefined,(4)a geographic coordinate system(GCS)that is correctly defined,(5)a GCS that is incorrectly defined,(6)a GCS that is undefined,and(7)a *** created automated troubleshooting tools to determine a missing map projection file are discussed.

关键词： GIS education map projection error map projection file define projection

Strategies for creating living, additively manufactured, open-cellular metal and alloy implants by promoting osseointegration,osteoinduction and vascularization: An overview

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Journal of Materials Science & Technology 2019年第2期35卷 231-241页

作者： Lawrence e.Murr department of Metallurgical Materials and Biomedical Engineering The University of Texas at El Paso W.M.Keck Center for 3D Innovation The University of Texas at El Paso

Additive manufacturing of porous, open-cellular metal or alloy implants, fabricated by laser or electron beam melting of a powder bed, is briefly reviewed in relation to optimizing biomechanical compatibility by assuring elastic(Young's) modulus matching of proximate bone, along with corresponding pore sizes assuring osseointegration and vasculature development and migration. In addition, associated, requisite compressive and fatigue strengths for such implants are described. Strategies for optimizing osteoblast(bone cell) development and osteoinduction as well as vascularization of tissue in 3 D scaffolds and tissue engineering constructs for bone repair are reviewed in relation to the biology of osteogenesis and neovascularization in bone, and the role of associated growth factors, bone morphogenic proteins, signaling molecules and the like. Prospects for infusing hydrogel/collagen matrices containing these cellular and protein components or surgically extracted intramedullary(bone marrow) concentrate/aspirate containing these biological and cell components into porous implants are discussed, as strategies for creating living implants, which over the long term would act as metal or alloy scaffolds.

关键词： Additive manufacturing Open cellular metal and alloy implants electron beam melting Living implant strategies Vascularization Osseointegration Osteoinduction

effect of Cambering on the Aerodynamic Performance of Heaving Airfoils

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Journal of Bionic engineering 2009年第4期6卷 398-404,406-407页

作者： Joel e.Guerrero Postdoctoral Research Fellow Department of CivilEnvironmental and Architectural EngineeringUniversity of GenoaVia Montallegro 1Genoa16145Italy

In the present work,a parametric numerical study is conducted in order to assess the effect of airfoil cambering on the aerodynamic performance of rigid heaving *** incompressible Navier-Stokes equations are solved in their velocity-pressure formulation using a second-order accurate in space and time finite-difference *** tackle the problem of moving boundaries,the governing equations are solved on overlapping structured *** numerical simulations are performed at a Reynolds number of Re=1100 and at different values of Strouhal number and reduced *** results obtained show that the airfoil cambering geometric parameter has a strong influence on the average lift coefficient,while it has a smaller impact on the average thrust coefficient and propulsive efficiency of heaving airfoils.

关键词： heaving airfoils structured overlapping grids incompressible Navier-Stokes equations airfoil cambering