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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

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

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

2019年

作者： (美)艾略特·温伯格

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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

Pollination systems, biogeography,and divergence times of three allopatric species of Schisandra in North America,China,and Japan

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Journal of Systematics and Evolution 2011年第4期49卷 330-338页

作者： Leonard b.THIEN Cell and Molecular biology Department Tulane University

This study analyses the pollination systems and biogeography of three allopatric species of Schisandra (Section Euschisandra) consisting of *** (North America),*** (China),and *** (Japan);the clade is delimited in a phylogenetic tree of Schisandraceae constructed with nuclear and plastid *** male and female flowers of these species have similar floral structures,but exhibit different pollination *** the base of the clade,*** is pollinated by a wide variety of beetles and flies in a generalist pollination system that also includes floral heat and the use of male and female flowers as brood sites for *** Asia,however,*** and *** are pollinated exclusively by one or two different species of gall midges (Resseliella spp.) in a specialist pollination *** this system only female,pollen-eating gall midges pollinate the flowers and breed on nearby *** gall midge pollination system is specialized and derived from the generalist system in ***,and basal in the *** is the main floral resource,and we hypothesize it is exploited to enrich eggs,and as a result species of gall midges could increase reproductive fitness by feeding on a single dependable food *** the life cycles of the plants and insects evolved into a tight association in old stable plant communities in the Sino-Japanese *** times for the plant species are presented and correlated with past distributions and migration routes.

关键词： biogeography Diptera phylogeny pollination Resseliella Schisandra.

Co-culture methods to study neuronal function and disease

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Neural Regeneration Research 2021年第5期16卷 972-973页

作者： Sarah b.Peters Division of biosciences College of DentistryThe Ohio State UniversityColumbusOHUSA

Co-culture methods to study neuronal function and disease:Injury,infection and degenerative diseases can occur throughout the body,potentially causing impaired organ function,loss of sensation,increased pain and/or tissue ***,researchers have begun to investigate ways to better mimic organ physiology by culturing neurons with the cell-type(s)-ofinterest toward the goals of regenerating organs that accurately communicate with autonomic and sensory-somatic nervous systems.

关键词： impaired sensation organs

Effect of oophorectomy and exogenous estrogen replacement on liver injury in experimental obstructive jaundice

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World Journal of Gastroenterology 2008年第18期14卷 2818-2824页

作者： Hamdi bülent Uan Mehmet Kaplan bülent Salman Utku YIlmaz b bülent Mentes Cemalettin Aybay Department of General Surgery Karaelmas University Medical School Zonguldak 67100 Turkey Department of General Surgery Gaziantep State Hospital Gaziantep Department of General Surgery Gazi University Medical School Ankara 06500 Turkey Department of Immunology Gazi UniversityMedical School Ankara 06500 Turkey

AIM: To investigate the role of estrogen on liver injury in an experimental obstructive jaundice ***: Three groups of female rats were constituted; group 1 was oophorectomized and given E2 (n = 14), group 2 was oophorectomized and given placebo (n = 14), and group 3 was sham operated (n = 14). Fourteen days following constitution of bile duct ligation, all groups were compared in terms of serum tests, histopathologic parameters, and tissue levels of IFN-γ and ***: The parameters representing both the injury and/or the reactive response and healing were more pronounced in groups 1 and 2 (χ2 = 17.2, χ2 = 10.20; χ2 = 12.4, P bo group (P bserved to be more pronounced in the groups 1 and 3 (χ2 = 6.13, P both the liver damage and healing. In the conditions of bile duct obstruction, estrogen significantly changed the cytokine milieu in the liver.

关键词： Estrogen Liver injury Oophorectomy Obstructive jaundice

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