检索结果-南通市图书馆

Chinese Physics B 2022年第5期31卷 107-112页

作者： Wen-Li Chen i B Okon School of intelligent Science and information Engineering Xi’an Peihua UniversityXi’an 710125China Theoretical Physics Group Department of PhysicsUniversity of UyoNigeria

Employing the Pekeris-type approximation to deal with the pseudo-centrifugal term,we analytically study the pseudospin symmetry of a Dirac nucleon subjected to equal scalar and vector modified Rosen-Morse potential including the spin-orbit coupling term by using the Nikiforov-Uvarov method and supersymmetric quantum mechanics *** complex eigenvalue equation and the total normalized wave functions expressed in terms of Jacobi polynomial with arbitrary spin-orbit coupling quantum number k are presented under the condition of pseudospin *** eigenvalue equations for both methods reproduce the same result to affirm the mathematical accuracy of analytical *** numerical solutions obtained for different adjustable parameters produce degeneracies for some quantum number.

关键词： Dirac equation modified Rosen-Morse potential Nikiforov-Uvarov method supersymmetric quantum mechanics approach

High Current and High intensity ion Beam Sources and Their Technological Applications

在线全文

学校读者我要写书评

暂无评论

稀有金属材料与工程 2011年第S4期40卷 142-146页

作者： A.i.Ryabchikov National Research Tomsk Polytechnic University TomskRussia

High-current ion beams have become a powerful tool for improving the surface properties of different *** prospects of wide commercial use of such beams for material treatment is not only due to the possibility of improving their properties,but,also for economic *** achieve a high throughput and reduce the cost on ion beam material treatment,ion beams of high average and pulsed power are *** paper gives an overview of work on generation of pulsed and repetitively pulsed beams of accelerated ions with currents ranging from fractions of an ampere to several tens of kA and with pulse duration from several tens of nanoseconds to several hundreds of microseconds.A number of different methods of materials surface properties modification using high power and intense ion beam and plasma are considered.

关键词： high current and intense ion beams plasma modification of materials coating deposition microparticle evaporation

Effect of graphene addition on the physicomechanical and tribological properties of Cu nanocomposites

在线全文

学校读者我要写书评

暂无评论

international Journal of Minerals,Metallurgy and Materials 2022年第1期29卷 161-167页

作者： Adnan i.Khdair A.ibrahim Mechanical Engineering Department Faculty of EngineeringKing Abdulaziz UniversityP.O.Box 80204JeddahSaudi Arabia Jordan University of Science and Technology Mech.Eng.Dep.P.O.Box 3030Irbid 2011Jordan Higher Technological institute Tenth of Ramadan CityEgypt

This paper presents an experimental investigation of the mechanical and tribological properties of Cu-graphene nanosheets(GN)*** employed the electroless coating process to coat GNs with Ag particles to avoid its reaction with Cu and the formation of intermetallic *** analyzed the effect of GN content on the structural,mechanical,and tribological properties of the produced *** showed that the electroless coating process is an efficient technique to avoid the reaction between Cu and C and the formation of intermetallic *** addition of GNs significantly improves the mechanical and tribological properties of Cu ***,the addition of GNs needs to be done carefully because,after a certain threshold value,the mechanical and tribological properties are negatively *** optimum GN content is determined to be 0.5vol%,at which hardness,wear rate,and coefficient of friction are im-proved by 13%,81.9%,and 49.8%,respectively,compared with Cu *** improved properties are due to the reduced crys-tallite size,presence of GNs,and homogenous distribution of the composite constituents.

关键词： copper graphene nanosheets coating mechanical properties wear

Optimizing the defensive characteristics of mild steel via the electrodeposition of Zn-Si3N4 reinforcing particles

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2019年第4期15卷 526-532页

作者： i.G. Akande O.O. Oluwole O.S.i. Fayomi Department of Mechanical Engineering University of Ibadan Ibadan Oyo state Nigeria Department of Mechanical Engineering Covenant University ota ogun state Nigeria Department of Chemical Metallurgical and Materials Engineering Tshwane University of Technology Pretoria South Africa

The effect of Zn-Si3 N4 deposition prepared via direct electrolytic co-deposition on mild steel was studied as a result its inherent vulnerability to corrosion in an aggressive environment and failure on the application of *** experiment was conducted varying the mass concentration of silicon nitride(Si3 N4)between 7 and 13 gat cell voltage of 0.3 and 0.5 V,at constant temperature of 45℃.The morphologies of the coated surfaces were characterized using high resolution Nikon Optical Microscope and Scanning Electron Microscope(SEM)revealing that the particles of the Zn-Si3 N4 were homogeneously *** corrosion behaviour was studied using potentiodynamic polarization technique in 3.65%NaCl solution and the microhardness was examined using Brinell hardness testing *** result of the corrosion experiment confirmed an improved corrosion resistance with a reduction in corrosion rate from 9.7425 mm/year to 0.10847 mm/year,maximum coating efficiency of 98.9%,maximum polarization resistance of 1555.3 Ω and a very low current density of 9.33 × 10-6A/*** negative shift in the Ecorr revealed the cathodic protective nature of the *** microhardness was also found to have increased from 137.9 HBN for the unmodified steel to a maximum value of 263.3 HBN for the0.5 Zn-13 Si3 N4 coated steel representing 90.9% increment in hardness as a result of the matrix grain refining and dispersion-strengthening ability of the incorporated Si3 N4 particles.

关键词： Polarization Corrosion Microhardness Coating Composite Matrix

Flow-Field of an Axisymmetric Lobed Mixer

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2004年第1期13卷 40-45页

作者： i.Yimer S.Manipurath i.Campbell W.E.Carscallen Gas Turbine Environmental Research Centre Aerodynamics LabInstitute for Aerospace ResearchNational Research Council Canada1200 Montreal RoadOttawaOntarioCanadaK1A 0R6

The flow-field of a fuel/air mixing system with an axisymmetric lobed mixer was numerically investigated. Large-scale streamwise vortices are formed immediately downstream of the mixer trailing edge, stretched further downstream, and finally broken into fragments where more intense mixing occurs. Both numerical and experimental results indicate that the length required for streamwise vortices breakdown in the confined flow-field of an axisymmetric lobed mixer is much shorter than that in the case of planar lobed mixers subject to parallel freestreams. For the conditions studied, the streamwise vortices start to breakdown at three wavelengths downstream of the mixer trailing edge.

关键词： axisymmetric lobed mixer confined flow fuel/air mixing

Monitoring Land Use Dynamics in Chanthaburi Province of Thailand Using Digital Remotely Sensed images

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2003年第2期13卷 157-164页

作者： SHENRUNPiNG i.KHEORUENROMNE DepartmentofLandResourceandEnvironmentscience JiangxiAgriculturalUniversityNanchang330045(China) DepartmentofsoilScience FacultyofAgricultureKasetsartUniversityBangkok10900(Thailand)

A comprehensive method of image classification was developed for monitoring land use dynamics in Chanthaburi Province of Tailand. RS (Remote Sensing), GiS (Geographical information System), GPS (Global Positioning System) and ancillary data were combined by the method which adopts the main idea of classifying images by steps from decision tree method and the hybridized supervised and unsupervised classification. An integration of automatic image interpretation, ancillary materials and expert knowledge was realized. Two subscenes of Landsat 5 Thematic Mapper (TM) images of bands 3, 4 and 5 obtained on December 15, 1992, and January 17, 1999, were used for image processing and spatial data analysis in the study. The overall accuracy of the results of classification reached 90%, which was verified by field *** showed that shrimp farm land, urban and traffic land, barren land, bush and agricultural developing area increased in area, mangrove, paddy field, swamp and marsh land, orchard and plantation, and tropical grass land decreased, and the forest land kept almost stable. Ecological analysis on the land use changes showed that more attentions should be paid on the effect of land development on ecological environment in the future land planning and management.

关键词： image classification land use dynamics remote sensing tropical area

Special Spectral Approach to Solutions of SiSO LTi H-Optimization Problems

在线全文

学校读者我要写书评

暂无评论

international Journal of Automation and computing 2019年第1期16卷 112-128页

作者： Evgeny i.Veremey Faculty of Applied Mathematics and Control Processes Saint-Petersburg State University

The paper is devoted to H-optimization problems for linear time invariant(LTi) systems with scalar control, external disturbance and measurement noise. All these problems can be numerically solved with the help of the well-known universal approaches based on Riccati equations, linear matrix inequalities(LMi) or maximum entropy technique. Nevertheless, in our opinion there exists a possibility to increase the computational efficiency of synthesis using a special spectral approach to the above mentioned problems in frequency domain. Some relevant details are discussed and efficient numerical algorithms are proposed for the practical implementation of spectral approach. One of its virtues is a possibility to present optimal solutions in a specific form, which is convenient for investigation.

关键词： Stabilizing controller performance index synthesis H-optimization spectral approach

MiNiMUM CONGESTiON SPANNiNG TREES iN BiPARTiTE AND RANDOM GRAPHS

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2011年第2期31卷 634-640页

作者： M.i. Ostrovskii Department of Mathematics and Computer Science St. John's University

The first problem considered in this article reads： is it possible to find upper estimates for the spanning tree congestion in bipartite graphs, which are better than those for general graphs？ it is proved that there exists a bipartite version of the known graph with spanning tree congestion of order n3/2, where n is the number of vertices. The second problem is to estimate spanning tree congestion of random graphs. it is proved that the standard model of random graphs cannot be used to find graphs whose spanning tree congestion has order greater than n3/2.

关键词： Bipartite graph random graph minimum congestion spanning tree

influence of Shallow and Deep Cryogenic Treatment on Tribological Behavior of En 19 Steel

在线全文

学校读者我要写书评

暂无评论

Journal of iron and Steel Research international 2011年第9期18卷 53-59页

作者： D Senthilkumar i Rajendran Department of Mechanical Engineering Dr Mahalingam College of Engineering and Technology

The influence of cryogenic treatment on the wear resistance of En 19 steel was studied. Furthermore, a comparative analysis on the effect of Deep Cryogenic Treatment （DCT, 196℃× 24 h）, Shallow Cryogenic Treatment （SCT -80℃ × 5 h） and Conventional Heat Treatment （CHT） was done through dry sliding wear testing. The microstructures of CHT, SCT and DCT samples were also examined through scanning electron microscopy. The results indicated that the wear resistance of shallow and deep cryogenically treated samples is higher when compared to that of conventionally treated samples. X-ray diffraction pattern revealed that the transformation of retained austenite into martensite is responsible for the wear resistance improvement.

关键词： steel wear cryogenic treatment automotive

Energy Decay in Thermoelasticity with Viscoelastic Damping of General Type

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2015年第2期31卷 331-344页

作者： Muhammad i.MUSTAFA King Fahd University of Petroleum and Minerals Department of Mathematics and Statistics

in this paper we consider an n-dimensional thermoelastic system with viscoelastic damping. We establish an explicit and general decay rate result without imposing restrictive assumptions on the behavior of the relaxation function at infinity. Our result allows a larger class of relaxation functions and generalizes previous results existing in the literature.

关键词： Thermoelasticity viscoelastic damping general decay convexity