检索结果-南通市图书馆

FIRST-ORDeR meTHODS FOR SOLVING THe OPTImAL STATIC H∞-SYNTHeSIS PROBLem

在线全文

学校读者我要写书评

暂无评论

Journal of Computational mathematics 2007年第6期25卷 672-689页

作者： el-Sayed m.e. mostafa Department of mathematics Faculty of Science Alexandria University Alexandria Egypt

In this paper, we consider the static output feedback （SOF） H∞-synthesis problem posed as a nonlinear semi-definite programming （NSDP） problem. Two numerical algorithms are developed to tackle the NSDP problem by solving the corresponding Karush- Kuhn-Tucker first-order necessary optimality conditions iteratively. Numerical results for various benchmark problems illustrating the performance of the proposed methods are given.

关键词： Static output feedback H∞-synthesis Semi-definite programming Nonlinear programming.

eNHANCemeNT OF ReSISTANCe TO OXIDATIVe DeGRADATION OF NATURAL RUBBeR THROUGH LATeX DeGRADATION

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

Chinese Journal of Polymer Science 1998年第2期16卷 170-175页

作者： NWANORH K.O. eNYIeGBULAm m.e. School of Physical Sciences ABIA State University P.M.B. 2000 Uturu NigeriaDepartment of Polymer & Textile Engineering Federal University of Technology P.M.B. 1526 Owerri Nigeria

A fully characterised natural rubber latex was subjected to mechanical degradation by stirring at intervals. The resistance to oxidative degradation of the different samples were studied by measuring the Plasticity retention indices (PRI). The results show that there is an enhancement of the PRI from 57% for the undegraded rubber to 79% for the one-hour degraded sample. Further degradation resulted in decrease of PRI as time of degradation increased. Therefore, the one-hour degraded sample is a special rubber with high oxidation resistance which is of great importance in engineering. (Author abstract) 9 Refs.

关键词： Plasticity Rubber Degradation Oxidation Resistance

A CONJUGATe GRADIeNT meTHOD FOR DISCReTe-TIme OUTPUT FeeDBACK CONTROL DeSIGN

在线全文

学校读者我要写书评

暂无评论

Journal of Computational mathematics 2012年第3期30卷 279-297页

作者： e1-Sayed m.e. mostafa Department of mathematics Faculty of Science Alexandria University Alexandria Egypt

In this paper, the discrete-time static output feedback control design problem is con- sidered. A nonlinear conjugate gradient method is analyzed and studied for solving an unconstrained matrix optimization problem that results from this optimal control prob- lem. In addition, through certain parametrization to the optimization problem an initial stabilizing static output feedback gain matrix is not required to start the conjugate gradi- ent method. Finally, the proposed algorithms are tested numerically through several test problems from the benchmark collection.

关键词： Output feedback control Nonlinear conjugate gradient methods Nonlinearprogramming.

STUDY ON THe PROPeRTIeS OF BLeND OF NATURAL RUBBeR LATeX/meTHYL meTHACRYLATe GRAFTeD RUBBeR LATeX BY GAmmA RADIATION

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

Chinese Journal of Polymer Science 2007年第5期25卷 519-523页

作者： N.C. Dafader m.e. Haque F. Akhtar Nuclear and Radiation Chemistry Division Institute of Nuclear Science ＆ Technology Bangladesh Atomic Energy Commission P. O. Box 3787 Dhaka Bangladesh

Natural rubber latex （NRL） and methyl methacrylate （mmA） grafted rubber latex were blended in different ratios and irradiated at various absorbed doses by gamma rays from Co-60 source at room tem.e.ature. The tensile properties, swelling ratio and permanent set were measured. The maximum tensile strength and modulus at 500% elongation were obtained at an absorbed dose of 8 kGy. modulus increases from 6.99 mPa to 9.87 mPa for an increase in proportion of mmA grafted rubber from 40% to 60% in the blend at similar absorbed dose. elongation at break and swelling ratio decrease with increasing absorbed dose as well as the mmA grafted rubber content in the blends. The decreasing trend of permanent set is high up to 5 kGy absorbed dose, and beyond that dose, it becomes almost flat.

关键词： Natural rubber latex mmA grafted rubber latex Blend rubber Irradiation Cross-link.

Oxidation Resistance of the Aluminide Coating Formed on Carbon Steels

在线全文

学校读者我要写书评

暂无评论

Journal of materials Science & Technology 1997年第5期13卷 383-388页

作者： Soliman, H.m. mohamed, K.e. Abd el-Azim, m.e. Hammad, F.H. metallurgy Dept. Atomic Energy Authority Cairo Egypt

Low and medium carbon steels were aluminized by the pack aluminizing technique using halideactivated pure-Al and Fe-Al packs. The effect of mixture composition, aluminizing tem.e.atureand time and C content of the steel substrate on the structure and thickness of the aluminidelayer, and on the oxidation resistance was investigated. The optimum oxidation resistance canbe achieved with a low carbon steel substrate when the intermetallic phases Fe3Al and FeAlform the surface of the aluminide layer. In this case, the Al concentration at the surface of thealuminide coating is at least ≥15 wt pct. Formation of high Al concentration phases (FeAl3 andFe2Al5) during aluminizing should be avoided as they tend to embrittle the aluminide layer andreduce its oxidation resistance.

关键词： OO Figure Oxidation Resistance of the Aluminide Coating Formed on Carbon Steels

THe HADAmARD INeQUALITY FOR CONVeX FUNCTION VIA FRACTIONAL INTeGRALS

在线全文

学校读者我要写书评

暂无评论

Acta mathematica Scientia 2013年第5期33卷 1293-1299页

作者： m.e.ZDemR S.S.DRAGOmIR C.YILDIZ Department of mathematics K.K.Education Faculty Atatürk University School of engineering & Science Victoria University

In this paper, we establish several inequalities for some differantiable mappings that are connected with the Riemann-Liouville fractional integrals. The analysis used in the proofs is fairly elementary.

关键词： Hadamard's inequality convex functions power-mean inequality Riemann-Liouville fractional integration

The Teodorescu Operator in Clifford Analysis

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of mathematics,Series B 2012年第4期33卷 625-640页

作者： F.BRACKX H.De SCHePPeR m.e. LUNA-eLIZARRARS m.SHAPIRO Clifford Research Group Faculty of Engineering and Architecture Ghent University Belgium Instituto Politcnico Nacional mexico City Mexico

euclidean Clifford analysis is a higher dimensional function theory centred around monogenic functions, i.e., null solutions to a first order vector valued rotation in- variant differential operator called the Dirac operator. more recently, Hermitian Clifford analysis has emerged as a new branch, offering yet a refinement of the euclidean case; it focuses on the simultaneous null solutions, called Hermitian monogenic functions, to two Hermitian Dirac operators and which are invariant under the action of the unitary group. In euclidean Clifford analysis, the Teodorescu operator is the right inverse of the Dirac operator __0. In this paper, Teodorescu operators for the Hermitian Dirac operators c9~_ and 0_~, are constructed. moreover, the structure of the euclidean and Hermitian Teodor- escu operators is revealed by analyzing the more subtle behaviour of their components. Finally, the obtained inversion relations are still refined for the differential operators is- suing from the euclidean and Hermitian Dirac operators by splitting the Clifford algebra product into its dot and wedge parts. Their relationship with several complex variables theory is discussed.

关键词： Clifford analysis Teodorescu operator Dirac operator

Predatory pollinator deception： Does the orchid mantis resemble a model species？

在线全文

学校读者我要写书评

暂无评论

Current Zoology 2014年第1期60卷 90-103页

作者： J.C. O'HANLON G. I. HOLWeLL m.e. HeRBeRSTeIN Department of Biological Sciences Macquarie University North Ryde 2109 Australia School of Biological Sciences University of Auckland Auckland 1142 New Zealand

Cases of im.e.fect or non-model mimicry are common in plants and animals and challenge intuitive assumptions about the nature of directional selection on mimics. many non-rewarding flower species do not mimic a particular species, but at- tract pollinators through ＇generalised food deception＇. Some predatory animals also attract pollinators by resembling flowers, perhaps the most well known, yet least well understood, is the orchid mantis Hymenopus coronatus. This praying mantis has been hypothesised to mimic a flower corolla and we have previously shown that it attracts and captures pollinating insects as prey. Predatory pollinator deception is relatively unstudied and whether this occurs through model mimicry or generalised food decep- tion in the orchid mantis is unknown. To test whether the orchid mantis mimics a specific model flower species we investigated similarities between its morphology and that of flowers in its natural habitat in peninsular malaysia. Geometric morphometrics were used to compare the shape of mantis femoral lobes to flower petals. Physiological vision models were used to compare the colour of mantises and flowers from the perspective of bees, flies and birds. We did not find strong evidence for a specific model flower species for the orchid mantis. The mantis＇ colour and shape varied within the range of that exhibited by many flower pet- als rather than resembling one type in particular. We suggest that the orchid mantis resembles an average, or generalised flower-like stimulus. Thus predatory pollinator deception in the orchid mantis is likely to function as a form of generalised food deception, as opposed to model mimicry .

关键词： mimicry Orchid mantis Hymenopus coronatus Generalised food deception Aggressive mimicry

Ocellar lamprophyre dyke bearing mineralization,Wadi Nugrus,eastern Desert,egypt:Geology,mineralogy and geochemical implications

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

Chinese Journal Of Geochemistry 2010年第4期29卷 383-392页

作者： Ibrahim m.e. Saleh G.m. Dawood N.A. Aly G.m. Nuclear materials Authority P.O.Box 530El-MaadiCairoEgypt

The ocellar lamprophyre dyke(eNe-WSW) is recorded at Wadi Nugrus,eastern Desert,*** cuts porphyritic biotite granites and varies in thickness from 0.5 to 1.5 m and up to 3 km in *** lamprophyre dyke has been altered,and it is characterized by porphyritic and panidiomorphic textures with plagioclase,olivine,and augite constituting the porphyritic phase in a fine groundmass of the same ***,titanite,apatite,fluorite,graphite,calcite,allanite,autunite and Fe-Ti oxides are accessory ***,chlorite and epidote are secondary *** and hematitization are *** to sub-rounded porphyritic and zoned ocelli with radiate or brush-like shapes are generally common and represent physical traps for *** ocellar features are interpreted to represent the late stage of magmatic segregation or magmatic crystallization involving two immiscible magmatic *** studies of altered lamprophyre samples,based on X-ray diffraction(XRD) and environmental scanning electron microscopy(eSem),indicate the presence of secondary uranium minerals(autunite and uranophane),associated with gold,silver,nickel,atacamite,molybdenum,pyrite and *** presence of kaolinite indicates a high tem.e.ature *** mixing of volatile fluids with meteoric water and fluid-wall rock interaction result in changes of pH and oxygen activity and deposition of base metals in reducing environs(graphite and pyrite).Precipitation of hematite probably decreased the pH of the solution and rose acidic *** sudden change in pH and tem.e.ature of the fluids would lead to destabilization of base metal complexes favoring their *** magma source of the Nugrus lamprophyre is determined to be between calc-alkaline and alkaline and it has HKCAB and shoshonitic nature and may be derived from decomposition melting of such a metasomatised lithospheric *** is a major fractional phase to account for a rapid

关键词：煌斑岩脉矿物学地球化学沙漠埃及地质学黑云母花岗岩矿化