检索结果-南通市图书馆

Applied mathematics and mechanics(English Edition) 2012年第6期33卷 797-816页

作者： m.kumar R.SAINI Department of mathematics Kurukshetra University

The propagation of elastic waves is studied in a porous solid saturated with two immiscible viscous fluids. The propagation of three longitudinal waves is represented through three scalar potential functions. The lone transverse wave is presented by a vector potential function. The displacements of particles in different phases of the aggregate are defined in terms of these potential functions. It is shown that there exist three longitudinal waves and one transverse wave. The phenomena of reflection and refraction due to longitudinal and transverse waves at a plane interface between an elastic solid half-space and a porous solid half-space saturated with two immiscible viscous fluids are investigated. For the presence of viscosity in pore-fluids, the waves refracted to the porous medium attenuate in the direction normal to the interface. The ratios of the amplitudes of the reflected and refracted waves to that of the incident wave are calculated as a non- singular system of linear algebraic equations. These amplitude ratios are used to further calculate the shares of different scattered waves in the energy of the incident wave. The modulus of the amplitude and the energy ratios with the angle of incidence are computed for a particular numerical model. The conservation of the energy across the interface is verified. The effects of variations in non-wet saturation of pores and frequencies on the energy partition are depicted graphically and discussed,

关键词： dissipative porous solid immiscible viscous fluid elastic wave propagation,attenuation reflection and refraction coefficients

Reflection and refraction of plane waves at the boundary of an elastic solid and double-porosity dual-permeability materials

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2019年第2期16卷 298-317页

作者： m.kumar m.S.Barak m.kumari Department of mathematics B R Ambedkar Govt. College Department of mathematics Indira Gandhi University

Phenomena of reflection and refraction of plane harmonic waves at a plane interface between an elastic solid and doubleporosity dual-permeability material are investigated. The elastic solid behaves non-dissipatively, while double-porosity dual-permeability materials behave dissipatively to wave propagation due to the presence of viscosity in pore fluids. All the waves(i.e., incident and reflected) in an elastic medium are considered as homogeneous(i.e., having the same directions of propagation and attenuation), while all the refracted waves in double-porosity dual-permeability materials are inhomogeneous(i.e., having different directions of propagation and attenuation). The coefficients of reflection and refraction for a given incident wave are obtained as a non-singular system of linear equations. The energy shares of reflected and refracted waves are obtained in the form of an energy matrix. A numerical example is considered to calculate the partition of incident energy among various reflected and refracted waves. The effect of incident direction on the partition of the incident energy is analyzed with a change in wave frequency, wave-induced fluid-flow, pore-fluid viscosity and double-porosity *** has been confirmed from numerical interpretation that during the reflection/refraction process, conservation of incident energy is obtained at each angle of incidence.

关键词： Plane harmonic wave Double-porosity dual-permeability Reflection/refraction coefficients Energy share Elastic solid

Effect of various physical properties on the reflection coefficients of inhomogeneous waves at the stress-free surface of partially saturated soils induced by obliquely incident fast P-wave

在线全文

学校读者我要写书评

暂无评论

Journal of Ocean Engineering and Science 2022年第3期7卷 225-236页

作者： m.kumari m.S.Barak A.Singh m.kumar Department of mathematics M P College for WomenMandi Dabwali125104SirsaHaryanaIndia Department of mathematics Indira Gandhi University MeerpurRewari122503HaryanaIndia Department of mathematics Dr.B R Ambedkar Govt.CollegeDabwali125104SirsaHaryanaIndia

Ghasemzadeh and Abounouri[1]developed a mathematical model of partially saturated soils that is solved using the potential method,which decomposes elastodynamics equations into two standard wave equations,a scalar wave equation for scalar potential and a vector wave equation for vector *** such a medium,four waves exist three longitudinal and one *** fluid phase tortuous path is taken into account in this *** inertial coupling between solid and fluid particles is ***,both open-pore and sealed-pore boundaries are explored to investigate the reflection phenomenon at the surface of partially saturated *** both boundaries,the reflection coefficients of inhomogeneous waves at a partially saturated soil surface are found as a non-singular set of linear *** waves(both reflected and incident)in partially saturated soils are pronounced as inhomogeneous due to viscosity in pore fluids(i.e.,distinct directions of attenuation and propagation).The energy shares of reflected waves are determined using an energy matrix.A numerical example is used to determine the reflection coefficients and the distribution of incident energy among the various reflected *** effect of different physical features on reflection coefficients and incident energy partitioning is illustrated *** conservation of incident energy at the surface of partially saturated soils is mathematically confirmed at all angles of incidence.

关键词： Plane harmonic wave Inhomogeneous Partially saturated soils Reflection coefficients Energy shares

AW-7075-T6 sheet for shock heat treatment forming process

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Transactions of Nonferrous metals Society of China 2017年第10期27卷 2156-2162页

作者： m.kumar LKR Leichtmetallkompetenzzentrum Ranshofen GmbH Austrian Institute of TechnologyLamprechtshausnerstrasse 61 postfach 265282 Ranshofen Austria EBNER Industrieofenbau GmbH Ebner-Platz 14060 Leonding Austria

The forming behaviour of AW-7075-T6sheet was studied across a range of shock heat treatment(SHT)temperatures of200?480°*** SHT,formability of the samples was investigated by tension and deep drawing tests at room *** scanning calorimetry(DSC)was used to study the precipitation states of the AW-7075sheet in the as-received and shockheat treated *** was started to improve with increasing shock heat treatment temperature from300°C *** hardening resulted from the dissolution ofη′precipitates and the coarsening of remaining precipitates were found to contributeto the increase in formability at room ***-precipitation and coarsening of the precipitates were responsible for thepost-paint baking strength of SHT samples.

关键词： shock heat treatment forming AW-7075-T6 sheet formability precipitation kinetics

Estimation of carbon pools in secondary tropical deciduous forests of Odisha,India

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2021年第2期32卷 663-673页

作者： Subhashree Pattnayak m.kumar N.K.Dhal Sudam C.Sahu Department of Life Sciences Sambalpur UniversitySambalpurOdisha 768019India Environment and Sustainability Department CSIR-IMMTBhubaneswarOdisha 751013India Department of Botany North Orissa UniversityBaripadaOdisha 757003India

Secondary tropical forests sequester atmospheric CO 2 at relatively faster rates in vegetation and in soil than old-growth primary *** understanding of biomass and carbon stocks in different plant functional types of these forests is ***,diversity,composition,soil features and carbon stocks in six distinct plant functional types,namely:moist mixed-Deciduous Forest,Peninsular Sal Forest(PSF),Semi-Evergreen Forest(SEF),Planted Teak Forest,Bamboo Brakes(BB),and Degraded Thorny Shrubby Forest were quantified as secondary tropical deciduous forests of the Chandaka Wildlife Sanctuary,Eastern Ghats of Odisha,***-one species≥10 cm Girth at breast height(GBH)were recorded,belonging to 38 families and 65 ***-ground biomass carbon and soil organic carbon ranged from 2.1–72.7 mg C ha^(−1) and 20.6–67.1 mg C ha^(−1),respectively,among all plant functional *** organic carbon and important value index were positively correlated with above-ground biomass *** carbon allocation was in SOC pool(51–91%),followed by the above-ground biomass pool(9–52%),indicating SOC is one of the major carbon sinks in secondary dry *** results highlight the importance of secondary tropical deciduous forests in biodiversity conservation and ecological importance in reducing greenhouse gases.

关键词： Chandaka wildlife Sanctuary Diversity indices Soil organic carbon Above-ground biomass carbon Correlation study

Abrasive Wear Characteristics of Carbon and Low Alloy Steels for Better Performance of Farm Implements

在线全文

学校读者我要写书评

暂无评论

Journal of materials Science & Technology 1995年第2期11卷 91-96页

作者： m.kumar and R. C Gupta(Centre of Advanced Study, Dept. of metallurgical Engineering, Institute of Technology,Banaras Hindu University, Vaanasi -221 005, India) Banaraz Hindu Univ Varanasi India

The low stress abrasion behaviours of heat treated mild, medium carbon and high C - low Cr steels, which are generally used in making farm implements, have been investigated. The simple heat treatment greatly improves the hardness, tensile strength and abrasion resistance of medium carbon and high C - low Cr steels. The results indicate that the material removal during abrasion is controlled by a number of factors, such as hardness, chemical composition, microstructure and heat treatment conditions. The conclusion is that the heat treated high C - low Cr steel and mild steel carburized by using coaltar pitch provide the best hardness and abrasion resistance and thus appear to be the most suitable materials for making agricultural tools.

关键词： Abrasive Wear Characteristics of Carbon and Low Alloy Steels for Better Performance of Farm Implements mPa

Cryogenic forming behaviour of AW-6016-T4 sheet

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous metals Society of China 2017年第6期27卷 1257-1263页

作者： m.kumar N.SOTIROV F.GRABNER R.SCHNEIDER G.mOZDZEN LKR Leichtmetallkompetenzzentrum Ranshofen GmbH Austrian Institute of Technology Postfach 26 5282 Ranshofen Austria BENTELER Automobiltechnik GmbH An der Talle 27-31 33102 Paderborn Germany Voestalpine Polynorm GmbH & Co. KG PolynormstraB 1 73529 Schwabisch Gmund Germany Aerospace & Advanced Composites GmbH Viktor-Kaplan-Strasse 2 2700 Wiener Neustadt Austria

The objective of this work is to study the cryogenic sheet metal forming behaviour of precipitation hardening *** this regard,the flow curves and forming limit curves were obtained by tension and Nakazima experimental testing methods in thetemperature ranges from-196to25°*** was found that strength and elongation increase with decreasing *** butperceived differences between microstructure of the material deformed at the room and cryogenic temperatures respectively wereidentified by electron backscatter diffraction(EBSD)***,no significant difference in the precipitation kinetics duringcontinuous heating in the DSC has been *** study has demonstrated the potential of cryogenic forming by manufacturinga B-pillar part with8mm depth of side design element as compared to6mm at room temperature.

关键词： AW-6016-T4 alloy cryogenic forming strain hardening forming limit curve

Isolation of a Novel Population of multipotent Adult Stem Cells from Human Hair Follicles

在线全文

学校读者我要写书评

暂无评论

Isolation of a Novel Population of Multipotent Adult Stem Ce...

中华医学会第十二次全国皮肤性病学术会议

作者： Suresh m.kumar Thiennga K．Nguyen Geza Acs meenhard Herlyn Department of Pathology and Lab medicine University of Pennsylvania

Hair follicles are known to contain a well characterized niche for adult stem cells: the bulge, which contains epithelial and melanocytic stem cells. Using a human embryonic stem cell (hESC) culture condition, we isolated a population of adult stem cells from human hair follicles that are distinctively different from known epithelial or melanocytic stem cells. These cells do not express squamous or melanocytic markers, but express neural crest and neuron

关键词：

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

小麦氏腥黑粉病的抗性遗传

国外作物育种 2004年第4期23卷 12-13页

作者： m.kumar 向平

由印度尾孢黑粉菌引起的氏腥黑粉病侵染正在发育的籽粒，使籽粒品质下降。通过在旗叶期人为引起植株流行病条件来进行该病害的抗性筛选，但是该项工作费时、费力。已经进行了艰难的尝试，发现存在离体筛选的可能性。Arya(1999)和Tandon... 详细信息

由印度尾孢黑粉菌引起的氏腥黑粉病侵染正在发育的籽粒，使籽粒品质下降。通过在旗叶期人为引起植株流行病条件来进行该病害的抗性筛选，但是该项工作费时、费力。已经进行了艰难的尝试，发现存在离体筛选的可能性。Arya(1999)和Tandon等(2000)

关键词：小麦氏腥黑粉病抗性遗传籽粒品质旗叶期

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

1984世界大地测量系统(WGS84)

测绘科技通讯 1994年第2期17卷 40-42页

作者： m.kumar 朱慧

自1960年以来,美国国防制图局(DmA)已建立了四个世界大地测量系统(WGS);WGS60、WGS66、WGS72和WGS84。最新的WGS84与前三者相比,是最为精确的大地参考框架,它是利用了广泛的、最新的大地测量数据全球确定的。WGS84提供了精确的参照框架... 详细信息

自1960年以来,美国国防制图局(DmA)已建立了四个世界大地测量系统(WGS);WGS60、WGS66、WGS72和WGS84。最新的WGS84与前三者相比,是最为精确的大地参考框架,它是利用了广泛的、最新的大地测量数据全球确定的。WGS84提供了精确的参照框架、地球重力场模型、正常重力公式、大地水准面和包括全部大陆和主要海洋岛屿在内的105个局部(和区域)大地测量基准的转换参数。这些成果使测绘(mC&G)的复杂性明显地简化,并使国防制图局(DmA)的全球性成果在质量扣精度方面普遍得到提高。本文介绍对庞大数据组的研究和费时的计算,这些科研成果是令人感兴趣的,还给出应用WGS84去改善全球性测绘成果的方法和优点。

关键词：大地测量测量系统世界