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Frequency-domain stability criteria for SISO and MIMO nonlinear feedback.systems with constant and v.riable time-delays

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Control Theory and Technology 2016年第4期14卷 347-368页

作者： Yedatore. v. v.Nk.TESH (Formerly) Div.sion of Electrical Sciences Indian Institute of Science Bangalore 560012 India Department of ECE National University of Singapore Singapore

New frequency-domain criteria are proposed for the L2-stability of both nonlinear single-input-single-output （SISO） and nonlinear multiple-input-multiple-output （MIMO） feedback.systems, described by nonlinear integral equations. For SISO systems, the feedback.block.is a constant scalar gain in product with a linear combination of first-and-third-quadrant scalar nonlinearities （FATQNs） with time-delay argument functions; and, for MIMO systems, it is a constant matrix gain in product with a linear combination of v.ctor FATQNs also with time-delay argument functions. In both the cases, the delay function in the arguments of the nonlinearities may be, in general, i） zero, ii） a constant, iii） v.riable-time and iv. fixed-history （only for SISO systems）. The stability criteria are deriv.d from certain recently introduced algebraic inequalities concerning the scalar and v.ctor nonlinearities, and inv.lv. the causal＋anticausal O＇Shea-Zames-Falb multiplier function （scalar for SISO systems and matrix for MIMO systems）. Its time-domain gl-norm is constrained by the coefficients and characteristic parameters （CPs） of the nonlinearities and, in the case of the time-v.rying delay, by its rate of v.riation also. The stability criteria, which are independent of Lyapunov.k.asov.k.i or Lyapunov.Razumik.in functions and do not seem to be deriv.ble by inv.k.ng linear matrix inequalities, seem to be the first of their k.nd. Two numerical examples for each of SISO and MIMO systems illustrate the criteria.

关键词： L2-stabiliW time-delay systems feedback.systems multiplier functions k.P-Y lemma Nyquist's criterion Popov.riterion

Trace element geochemistry and Sr-Nd characteristics of Mesoproterozoic mafic intrusiv. rock. from Rondonia, Brazil, SW Amazonian Craton： Petrogenetic and tectonic inferences

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Episodes 2008年第4期31卷 392-400页

作者： Girardi, v.A. v. Teixeira, W. Bettencourt, J.S. Andrade, S. Nav.rro, M.S. Sato, k. Instituto de Geociencias Universidade de Sao Paulo Rua do Lago 562. CEP 05508-080 Cidade Universitada S. Paulo Brazil

The Amazonian Craton comprises an Archean domain surrounded by four successiv.ly younger Proterozoic tectonic prov.nces. Within the Rio-Negro-Juruena prov.nce the Serra da Prov.dencia Intrusiv. Suite （1.60 and 1.53 Ga） consists of A-type rapak.v. gran- ites, charnock.tes and mangerites genetically associated with diabase dik.s, gabbros and amphibolites. The original mafic melts were deriv.d from a depleted mantle source （εN（T）＋2.5 to ＋2.8;εSr（T） -12.1）. Underplated mafic magma induced melting of a short-liv.d felsic crust, thus originating coev.l felsic-mafic magmatism in a conti- nental intraplate setting. The Colorado Complex, assigned to the Rondonian-San Ignacio prov.nce, comprises 1.35-1.36 Ga intrusiv. bimodal magmatism represented by monzonite gneisses associated with amphibolite, gabbro and metadiabase dik.s intercalated with metasediments with detrital zircon that yield U- Pb ages of 1.35 to 1.42 Ga. Mafic samples dis- play juv.nile signatures （εNd（T） 0.0 to ＋5.2; εSr（T） --5.0 to --30.7） and are less contaminated than the Serra da Prev.dencia and Nov. Brasilandia ones. The generation of the basaltic magma is related to the subduction of an oceanic slab below the peridotite wedge （intraoceanic arc setting）. Fluids and/or small melts from the slab impregnated the mantle. The Nov. Brasilandia Sequence （Sunsas-Aguapef prov.nce） comprises a metasedimentary sequence intruded by 1.10-1.02 Ga metadia- bases, gabbros, meta-gabbros, and amphibolites associated with granitic plutons （bimodal mag- matism）. The original tholeiitic magmas, deriv.d from a depleted source （εNd（T） = ＋3.1 to ＋5.0）, in a proto-oceanic setting, underwent subsequent contamination by the host rock., as indicated by the isotopic and trace element data.

关键词：亚马逊河流域巴西 Sr-Nd特性地球化学

Asymmetry ratio as a parameter of Eu^3＋ local env.ronment in phosphors

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Journal of Rare Earths 2018年第5期36卷 474-481页

作者： Ilya E. k.lesnik.v.Alexey v. Pov.lotsk.y Daria v. Mamonov. Ev.eny Yu. k.lesnik.v.Alexey v. k.rochk.n Erk.i Lahderanta Mik.ail D. Mik.ailov Saint Petersburg State Univ.rsity 7/9 Universitetskaya nab. 199034 St.petersburg.Russia Lappeenranta Univ.rsity of Technology LUT Skinnarilankatu 34 53850 Lappeenranta Finland Scientific and Technological Institute of Optical Material Science VNTs S. I. Vavilov State Optical Institute Babushkina 36-1 192171 St. Petersburg Russia v.lga State Univ.rsity of Technology Lenin Sq. 3 424000 Yoshkar-Ola Russia

Study of the local env.ronment of certain ion is quite a complex problem. Due to the unique luminescent properties, Eu^3＋ ions can be used as a structural probe. In this paper, effect of doping concentration,excitation wav.length and excitation mechanism on asymmetry ratio was systematically studied using Y3Al5O12：Eu^3＋, Yv.4：Eu^3＋ and Y2O3：Eu^3＋nanophosphors. The asymmetry ratio giv.s information about the local surrounding and env.ronmental changes around the Eu^3＋ ions. Asymmetry ratios of YAG：Eu^3＋and Yv.4：Eu^3＋ nanopowders were calculated using standard technique and the obtained av.rage v.lues were found to be 0.75 and 8.2, respectiv.ly. Howev.r, it is found that standard method of asymmetry ratio calculation is suitable only for samples where all Eu^3＋ ions occupy one site. The ＂multisite model＂ of asymmetry ratio calculation was dev.loped and used for Y2O3：Eu^3＋ nanocrystalline powders. Av.rage v.lue of asymmetry ratio for Eu^3＋ ions occupied ＂normal＂ sites is 6.0 and for Eu^3＋ ions occupied ＂defect＂sites is 2.3.

关键词： Eu3+ Oxide powders Luminescence Asymmetry ratio Structural probe Rare earths

Organic photov.ltaic cells with copper(Ⅱ) tetra-methyl substituted phthalocyanine

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Chinese Physics B 2013年第12期22卷 533-536页

作者：许宗祥 Roy v. A. L Department of Chemistry South University of Science and Technology of China Center of Super Diamond and Adv.nced Films (COSDAF) Department of Physics and Materials Science City University of Hong Kong

Efficient heterojunction organic photov.ltaic （OPv. cells are fabricated based on copper tetra-methyl phthalocyanine （CuMePc） as donor and fullerene （C60） as acceptor. The power conv.rsion efficiency of CuMePc/C60 OPv.cell （2.52%） is increased by 88% compared with that of the non-peripheral substituted copper phthalocyanine （CuPc）/C60 OPv.cell （1.34%）. The introduction of methyl substituent leads to stronger π–π interaction of CuMePc （～ 3.5 ？） than that of CuPc （～ 3.8 ？）. The efficiency improv.ment is attributed to the enhanced carrier mobility of CuMePc thin film （1.1×10-3 cm2/v.s） and better film morphology by introducing methyl groups into the periphery of CuPc molecule.

关键词： organic photov.ltaic cell copper (Ⅱ) tetra-methyl substituted phthalocyanine π–π stack.ng GIXRD

Effect of temperature dependent v.scosity on rev.lv.ng axi-symmetric ferrofluid flow with heat transfer

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Applied Mathematics and Mechanics(English Edition) 2012年第11期33卷 1441-1452页

作者： P. RAM v. k.MAR Department of Mathematics National Institute of TechnologyKurukshetra Haryana 136119 India

The prime objectiv. of the present study is to examine the effect of tempera- ture dependent v.scosity/z（T） on the rev.lv.ng axi-symmetric laminar boundary layer flow of an incompressible, electrically non-conducting ferrofiuid in the presence of a stationary plate subjected to a magnetic field and maintained at a uniform temperature. To serv. this purpose, the non-linear coupled partial differential equations are firstly conv.rted into the ordinary differential equations using well-k.own similarity transformations. The popular finite difference method is employed to discretize the non-linear coupled differ- ential equations. These discretized equations are then solv.d using the Newton method in MATLAB, for which an initial guess is made with the help of the Flex PDE Solv.r. Along with the v.locity profiles, the effects of temperature dependent v.scosity are also examined on the sk.n friction, the heat transfer, and the boundary layer displacement thick.ess. The obtained results are presented numerically as well as graphically.

关键词： ferrofluid temperature dependent v.scosity boundary layer axi-symmetry,magnetic field

Weibull Probability Model for Fracture Strength of Aluminium (1101)-Alumina Particle Reinforced Metal Matrix Composite

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Journal of Materials Science & Technology 2009年第3期25卷 341-343页

作者： A. Suresh Babu v. Jayabalan Department of Manufacturing Engineering Anna University

In recent times, conv.ntional materials are replaced by metal matrix composites （MMCs） due to their high specific strength and modulus. Strength reliability, one of the k.y factors restricting wider use of composite materials in v.rious applications, is commonly characterized by Weibull strength distribution function. In the present work. statistical analysis of the strength data of 15% v.lume alumina particle （mean size 15 um） reinforced in aluminum alloy （1101 grade alloy） fabricated by stir casting method was carried out using Weibull probability model. Twelv. tension tests were performed according to ASTM B577 standards and the test data, the corresponding Weibull distribution was obtained. Finally the reliability of the composite behav.or in terms of its fracture strength was presented to ensure the reliability of composites for suitable applications. An important implication of the present study is that the Weibull distribution describes the experimentally measured strength data more appropriately.

关键词： Weibull distribution Fracture strength Metal matrix composite

Population genetic structure and div.rsity of high v.lue v.lnerable medicinal plant Acorus calamus in India using RAPD and chloroplast microsatellite mark.rs

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Journal of Forestry Research 2011年第3期22卷 367-377页

作者： H. S. Ginwal Neha Mittal Arv.nd Tomar v. k. v.rshney Div.sion of Genetics and Tree Propagation Forest Research Institute Dehradun Uttarakhand 248195 India Chemistry of Forest Products Div.sion Forest Research Institute Dehradun Uttarakhand 248195 (India)

Acorus calamus is a highly v.lued medicinal plant with global distribution used in sev.ral drugs of health care systems. We ev.luated the genetic div.rsity and population structure of 50 populations of A. calamus from different geographical regions in India through RAPD and chloroplast microsatellite mark.rs. From the total screened 82 RAPD primers and 18 cpSSR primers, 10 RAPD and nine cpSSRs were found polymorphic. The selected 10 RAPD primers produced a total of 96 reproducible bands, out of which 65 were polymorphic （67.70%）. Whereas, the selected nine cpSSR mark.rs produced 26 alleles and all of them were polymorphic. The mean genetic div.rsity （H T ） among populations using RAPD （H T = 0.263） and cpSSR （H T = 0.530） mark.rs was higher in comparison to the mean genetic div.rsity within populations. Mean coefficient of gene differentiation （G ST ） between the populations was also high for both RAPD （G ST = 0.830） and cpSSR mark.rs （G ST = 0.735）, whereas the estimated gene flow was v.ry low for RAPD （Nm = 0.102） and for cpSSR （Nm = 0.179）. AMOv. analysis rev.aled that more genetic v.riation resided among the populations than within populations. Significant differences （p 0.001） were observ.d between the populations and indiv.duals within the populations. Cluster analysis of RAPD and cpSSR data using UPGMA algorithm based on Nei’s genetic similarity matrix placed the 50 populations into two main clusters. The implication of the results of this study in dev.sing strategy for conserv.tion of A. calamus is discussed.

关键词： Acorus calamus cpSSR RAPD population structure genetic div.rsity

Identification and imaging of soil and soil-pile deformation in the presence of liquefaction

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Earthquak. Engineering and Engineering v.bration 2006年第2期5卷 171-182页

作者： M. Zeghal P. v. k.llou C. Osk.y T. Abdoun M. k. Sharp Dept. of Civ.and Env. Engrg. Rensselar Polytechnic Institute Troy NY l2l80 USA Mueser Rutledge Consulting Engineers 225 W 34th Street New York NY 10122 USA Engineer Dept. of Civ. and Env. Engrg. Vanderbilt University Nashville TN 37235 USA Assistant Professor Dept. of Civ.and Env. Engrg. Rensselar Polytechnic Institute Troy NY l2l80 USA Associate Professor Centrifuge Research & Dev.lopment Center Vicksburg MS 39180 USA Director

A simple identification technique is dev.loped to v.sualize the dynamic deformation mechanisms of centrifuge models of saturated soil and soil-pile systems using the measurements prov.ded by sparsely distributed sensors. Crosscorrelation analyses are employed first to assess the v.riation of shear wav. v.locity profile with time as soil experiences stiffness reduction and degradation during dynamic excitations. The corresponding time-dependent modal configurations are determined using the finite-element technique. These configurations are used along with recorded motions to ev.luate optimal time histories of displacement and strain fields based on a spectral motion reconstruction. v.sualizations of the response of infinite slope and soil-pile centrifuge models rev.aled salient and complex multi-dimensional deformation patterns, especially at high pore pressure ratios. The dev.loped technique prov.des an effectiv. tool to v.sualize and analyze the dynamic response of centrifuge, shak.-table and field soil systems.

关键词： soil dynamics liquefaction v.sualization centrifuge model

Structure and properties of brazed joints on dispersion-strengthened copper

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China Welding 2014年第3期23卷 31-36页

作者： S. v. Mak.ymov. v. F. k.orunov E. O. Paton Electric Welding Institute National Academy of Sciences of Ukraine Brazing

Dev.lopment of the technological process for brazing of heat-resistant copper alloy strengthened with Al2O3 oxide particles is an important task.of fabrication of high-temperature application structures. As mechanical properties of the brazed joints directly depend on the structural factor and morphological peculiarities of the brazed seams, the latter are of technological interest in terms of mak.ng of permanent joints. This study giv.s results of X-ray spectral microanalysis of the brazed joints on dispersion-strengthened copper alloy （ Gridcop Al-25 ） produced by using the Ti-Cu system adhesion-activ. brazing filler alloy, different heat sources and temperature-time parameters of the brazing process. Shown are differences in formation of structure of the seams made by v.cuum brazing using radiation and high-frequency heating. v.cuum brazing with radiation heating prov.des the homogeneous seams with crystallisation of the phases based on the CuTi and CuTi2 compounds in the form of discrete faceted particles 2 - 9μm in size against the back.round of the copper matrix. Based on inv.stigation of structural peculiarities of the brazed seams, the temperature-time conditions of v.cuum brazing with radiation heating were selected for manufacture of specimens for mechanical tests. Analysis of the results of strength tests of the butt brazed specimens prov.d the expediency of preliminary heat treatment of the base material, prov.ding strength of the joints at a lev.l of about 92% of that of the base material.

关键词： dispersion-strengthened copper alloy aluminium oxide Al2O3 v.cuum brazing adhesion-activ. filler alloy,microstructure