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Theoretical and numerical investigation of HF elastic wave propagation in two-dimensional periodic beam lattices

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Acta Mechanica Sinica 2013年第6期29卷 783-798页

作者： b.Tie b.Y.Tian D.Aubry Laboratory MSSMat(UMR-CNRS 8579) Ecole Centrale ParisGrande Voie des Vignes92295 Chatenay-Malabry CedexFrance

The elastic wave propagation phenomena in two-dimensional periodic beam lattices are studied by using the bloch wave transform. The numerical modeling is applied to the hexagonal and the rectangular beam lattices, in which, both the in-plane （with respect to the lattice plane） and out-of-plane waves are considered. The dispersion relations are obtained by calculating the bloch eigenfrequencies and eigenmodes. The frequency bandgaps are observed and the influence of the elastic and geometric properties of the primitive cell on the bandgaps is studied. by analyzing the phase and the group velocities of the bloch wave modes, the anisotropic behaviors and the dispersive characteristics of the hexagonal beam lattice with respect to the wave prop- agation are highlighted in high frequency domains. One im- portant result presented herein is the comparison between the first bloch wave modes to the membrane and bend- ing/transverse shear wave modes of the classical equivalent homogenized orthotropic plate model of the hexagonal beam lattice. It is shown that, in low frequency ranges, the homog- enized plate model can correctly represent both the in-plane and out-of-plane dynamic behaviors of the beam lattice, its frequency validity domain can be precisely evaluated thanks to the bloch modal analysis. As another important and original result, we have highlighted the existence of the retro- propagating bloch wave modes with a negative group veloc- ity, and of the corresponding ＂retro-propagating＂ frequency bands.

关键词： Elastic wave propagation Periodic beam lattice bloch wave theory bandgaps Anisotropy Disper- sion relation

The gravity field and gravity data reduction across the continental area of Nigeria

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Geodesy and Geodynamics 2023年第3期14卷 304-320页

作者： Oluwatimilehin b.balogun Isaac b.Osazuwa Department of Geosciences Mountain Top UniversityPrayer CityOgun StateNigeria Department of Geophysics Federal UniversityOye-EkitiEkiti StateNigeria

This research presents the variation of the gravity field and associated gravity field components over the continental area of Nigeria to provide data for geoscience research,geodetic and engineering works,aerodynamic studies and deep crustal *** positions and elevations were observed at 58 of the 59 base stations of the Primary Gravity Network of Nigeria(PGNN),whose absolute gravity values had been accurately *** absolute gravity values were plotted against their respective positions to reveal the distribution pattern and strength of the gravity field within the study *** gravity values at each base station were generated using the Somigliana's *** free-air gravity and free-air anomaly gravity values were generated with respect to the World Geodetic System 1984(WGS84)ellipsoid using GPS-derived elevation ***,the perturbing potential,free-air gravity with respect to the geoid,and the indirect effects were *** average of the indirect effects was used to adjust the WGS84 gravity formula to produce a gravity formula that better approximates the geoid across the continental area of Nigeria,compatible with the heights measured relative to the geoid,which can serve as a reference for establishing a vertical height *** bouguer gravity and bouguer gravity anomalies across Nigeria revealed a“trans-southern gravity high strip”interpreted to be associated with mantle *** new major mega-lineaments related to mantle upwelling were mapped.A batholith province trending NWeSE was delineated,occurring from north central Nigeria to the north western region and containing closures of“bouguer gravity lows”interpreted as batholiths.A separate closure of“bouguer gravity low”was detected at Azare,north eastern Nigeria,which may be due to the presence of intrusive granitic *** is recommended that the mantle structure beneath“the trans-southern gravity high strip”,“delineated batholith province”and“isolat

关键词： Absolute gravity Continental Nigeria landmass Primary gravity network of Nigeria(PGNN) WGS84 ellipsoid Indirect effect Height datum

Earth return path impedances of underground cable for three-layer earth

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第8期10卷 1191-1198页

作者： b.HEMMATIAN b.VAHIDI S.H.HOSSEINIAN Department of Electrical Engineering Amirkabir University of Technology

One of the factors that affect the parameters of an underground cable is earth return path *** developed a formula for the case of one-layer(homogenous) *** in practice the earth is composed of several *** this study we develop a new formula for earth return path impedance in the case of a three-layer *** check the accuracy of the obtained results,a comparison has been made with the finite element method(FEM).A comparison between the results of the Pollaczek formula and results of the obtained formula for a three-layer earth has been made,showing that the use of the Pollaczek formula instead of the actual formula can cause serious errors.

关键词： Underground cables Earth return path impedance Earth stratification Finite element method (FEM)

Principles to Support Modular Software Construction

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Journal of Computer Science & Technology 2017年第1期32卷 3-10页

作者： Jack b. Dennis Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA 02139 U.S.A.

The construction of large software systems is always achieved through assembly of independently written components -- program modules. For these software components to work together, they must share a common set of data types and principles for representing structured data such as arrays of values and files. This common set of tools for creating and operating on data objects is provided by the infrastructure of the computer system： the hardware, operating system and runtime code. because the nature and properties of these tools are crucial for correct operation of software components and their inter-operation, it is essential to have a precise specification that may be used for verifying correctness of application software on one hand, and to verify correctness of system behavior on the other. We call such a specification a program execution model （PXM）. It is evident that the properties of the PXM implemented by a computer system can have serious impact on the ability of application programmers to practice modular software construction. This paper discusses the concept of program execution models and presents a set of principles that a PXM must satisfy to provide a sound basis for modular software construction. because parallel program execution on computer systems with many processing units is an essential part of contemporary computing environments, the expression of parallelism and modular software construction using components involving parallel operations is included in this treatment. The conclusion is that it is possible to build computer systems that implement a PXM within which any parallel program may be used, unmodified, as a component for building more substantial parallel programs.

关键词： program execution model data flow model codelet abstract architecture parallel computing

Role of vitamin b12 deficiency in ischemic stroke risk and outcome

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Neural Regeneration Research 2021年第3期16卷 470-474页

作者： Gyllian b.Yahn Jamie E.Abato Nafisa M.Jadavji Department of biomedical Sciences Midwestern UniversityGlendaleAZUSA Department of Neuroscience Carleton UniversityOttawaONCanada

Currently,ischemic stroke is the most prevalent form of stroke compared to hemorrhagic and there is a high incidence in older *** is a modifiable risk factor for stroke.b-vitamins are part of a metabolic network that integrates nutritional signals with biosynthesis,redox homeostasis,and *** vitamins play an essential role in the regulation of cell proliferation,stress resistance,and embryo development.A deficiency in vitamin b12 is common in older adults and has been reported to be implicated in ischemic *** aim of this review was to investigate whether vitamin b12 deficiencies impact the risk and outcome of ischemic *** data from our literature review strongly suggest that a deficiency in vitamin b12 is a risk factor for ischemic stroke and possible *** survey of the literature has identified that there is a gap in the understanding of the mechanisms through which a vitamin b12 deficiency leads to an increased risk of stroke and outcome.A vitamin b12 deficiency can increase homocysteine levels,which are a well-established risk factor for ischemic *** potential mechanism through which vitamin b12 deficient may impact neurological function and increase risk of stroke,is changes in myelination,however this link requires further *** studies are required in model systems to understand how a vitamin b12 deficiency changes the brain.

关键词： b-vitamins ischemic stroke one-carbon vitamin b12

A comprehensive approach to an equation of state for hard spheres and Lennard Jones fluids

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Chinese Physics b 2011年第8期20卷 271-278页

作者： S.b.Khasare 90 New Jagruti Colony Katol Road NagpurIndia

We present a simple method of obtaining various equations of state for hard sphere fluid in a simple unifying way. We will guess equations of state by using suitable axiomatic functional forms （n = 1, 2, 3, 4, 5） for surface tension Sn （r）, r≥ d/2 with intermolecular separation r as a variable, where m is an arbitrary real number （pole）. Among the equations of state obtained in this way are Percus-Yevick, scaled particle theory and Carnahan-Starling equations of state. In addition, we have found a simple equation of state for the hard sphere fluid in the region that represents the simulation data accurately. It is found that for both hard sphere fluids as well as Lennard-Jones fluids, with m = 3/4 the derived equation of state （EOS） gives results which are in good agreement with computer simulation results. Furthermore, this equation of state gives the Percus-Yevick （pressure） EOS for the m = 0, the Carnahan-Starling EOS for rn = 4/5, while for the value of m = 1 it corresponds to a scaled particle theory EOS.

关键词： equation of state Lennard-Jones potential hard-sphere potential computer algebra,computer simulation

On a biseparability criterion of bipartite qudit state

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Chinese Physics b 2019年第8期28卷 42-49页

作者： b benzimoun M Daoud LPHE-Modeling and Simulation Faculty of SciencesUniversity Mohammed ⅤRabatMorocco Department of Physics Faculty of Sciences-Ain ChockUniversity Hassan ⅡCasablancaMorocco Abdus Salam International Centre for Theoretical Physics TriesteItaly

In this paper,we propose a new approach to tackle the separability problem for bipartite qudit *** is based on the Majorana representation which allows to represent a N-spinors(qudit)as a symmetric state of N spin-1/*** also discuss how we can exploit such representation and the notion of the biseparability of multipartite qubit states in the sense to establish new criteria of the separability problem based on the PPT and concurrence.

关键词： separability bipartite qubit state partial separability Majorana representation

Effect of Al_(2)O_(3)on the Mechanical Properties of(b_(4)C+Al_(2)O_(3))/Al Neutron Absorbing Materials

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Acta Metallurgica Sinica(English Letters) 2024年第8期37卷 1411-1420页

作者： J.X.Cai b.M.Shi N.Li Y.Liu Z.G.Zhang Y.N.Zan Q.Z.Wang b.L.Xiao Z.Y.Ma Shi‑Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Nuclear Equipment Division Beijing Institute of Nuclear EngineeringChina Nuclear Power Engineering Co.Ltd.Beijing 100840China Department of Materials Science School of Mechanical EngineeringShenyang UniversityShenyang 110044China

b_(4)C/Al composites are widely utilized as neutron absorbing materials for the storage and transportation of spent nuclear *** order to improve the high-temperature mechanical properties of b_(4)C/Al composites,in-situ nano-Al_(2)O_(3)was introduced utilizing oxide on Al powder *** this study,the Al_(2)O_(3)content was adjusted by utilizing spheroid Al powder with varying diameters,thereby investigating the impact of Al_(2)O_(3)content on the tensile properties of(b_(4)C+Al_(2)O_(3))/Al *** was found that the pinning effect of Al_(2)O_(3)on the grain boundaries could hinder the recovery of dislocations and lead to dislocation accumulation at high *** the result,with the increase in Al_(2)O_(3)content and the decrease in grain size,the high-temperature strength of the composites increased *** finest Al powder used in this investigation had a diameter of 1.4μm,whereas the resultant composite exhibited a maximum strength of 251 MPa at room temperature and 133 MPa at 350℃,surpassing that of traditional b_(4)C/Al composites.

关键词： Al matrix composites Neutron absorbing materials (b_(4)C+Al_(2)O_(3))/Al composites High-temperature strength

biodiversity and interactions of acidophiles:Key to understanding and optimizing microbial processing of ores and concentrates

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中国有色金属学会会刊：英文版 2008年第6期18卷 1367-1373页

作者： D.b.JOHNSON School of biological Sciences Bangor University

采矿公司为从低档矿石恢复贱、宝贵的金属，并且为重新调停变得逐渐地知道 microbiological 途径的潜力从操作和放弃的矿地点排干的酸的、充满金属的废水。生物系统出现很多环境并且(有时) 超越常规途径的节俭的优点尽管他们的申请是，... 详细信息

采矿公司为从低档矿石恢复贱、宝贵的金属，并且为重新调停变得逐渐地知道 microbiological 途径的潜力从操作和放弃的矿地点排干的酸的、充满金属的废水。生物系统出现很多环境并且(有时) 超越常规途径的节俭的优点尽管他们的申请是，例如热冶学，别处于每种状况拨出。矿物质用微生物处理为提取黄金，铜，铀和钴被利用了，并且当前的开发正在指向另外的贱金属。最近，我们 biomining 环境，并且微生物怎么与对方一起交往的微生物学的差异的知识和理解有大增加。从模仿了搅动的坦克和堆生物反应器系统的实验室实验的结果证明了微生物引起的协会比氧化矿物质的 acidophiles 的纯文化更柔韧，并且也趋于在 bioleaching 和氧化简历的矿石更有效并且专注。纸论述了性质的简明评论和涉及硫化物矿物质的氧化的微生物引起的协会的相互作用，并且这些怎么可能被改编在 biomining 操作遇见未来挑战。

关键词：嗜酸细胞生物采矿生物多样性微生物加工