检索结果-南通市图书馆

A TWO-SURFACE MODEL DESCRIBING RATCHETTING BEHAVIORS AND TRANSIENT HARDENING UNDER NONPROPORTIONAL LOADING

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 1996年第4期12卷 368-376页

作者：陈旭 A.abel Dept.of Chemical Engineering Tianjin UniversityTianjin300072China School of Civil and Mining Engineering The University of SydneyNSW 2006Australia

A new superposed rule of Mroz's kinematic hardening rule and Ziegler's kinematic hardening rule based on two-surface model is proposed in the paper. Some experimental results on ratchetting of 2014-T6 aluminum alloy are predicted very well under multiaxial loading. In addition the conformability of the model is discussed for transient cyclic hardening under two kinds of nonproportional cyclic loading paths., i.e. square and rhombic path.

关键词： nonproportional loading multiaxial loading ratchetting two-surface model cyclic hardening

Combustion Irreversibilities: Numerical Simulation and Analysis

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2012年第4期21卷 377-383页

作者： Valter Silva abel Rouboa CITAB/Engineering Department School of Science and Technology of University of U TAD Mechanical Engineering and Applied Mechanics Department University of PennsylvaniaPhiladelphia

An exergy analysis was performed considering the combustion of methane and agro-industrial residues produced in Portugal (forest residues and vines pruning). Regarding that the irreversibilities of a thermodynamic process are path dependent, the combustion process was considering as resulting from different hypothetical paths each one characterized by four main sub-processes: reactant mixing, fuel oxidation, internal thermal energy exchange (heat transfer), and product mixing. The exergetic efficiency was computed using a zero dimensional model developed by using a Visual Basic home code. It was concluded that the exergy losses were mainly due to the internal thermal energy exchange sub-process. The exergy losses from this sub-process are higher when the reactants are preheated up to the ignition temperature without previous fuel oxidation. On the other hand, the global exergy destruction can be minored increasing the pressure, the reactants temperature and the oxygen content on the oxidant stream. This methodology allows the identification of the phenomena and processes that have larger exergy losses, the understanding of why these losses occur and how the exergy changes with the parameters associated to each system which is crucial to implement the syngas combustion from biomass products as a competitive technology.

关键词： Exergy Combustion paths Combustion sub-processes Exergetic efficiency Visual Basic Syngas

THE ENERGY FUNCTION WITH RESPECT TO THE ZEROS OF THE EXCEPTIONAL HERMITE POLYNOMIALS

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2017年第5期37卷 1483-1496页

作者： Agota P.horvath Department of Analysis Budapest University of Technology and EconomicsEgry J.u 1-3BudapestHungary

We examine the energy function with respect to the zeros of exceptional Hermite polynomials. The localization of the eigenvalues of the Hessian is given in the general *** some special arrangements we have a more precise result on the behavior of the energy function. Finally we investigate the energy function with respect to the regular zeros of the exceptional Hermite polynomials.

关键词： exceptional Hermite polynomials system of minimal energy energy function partitioned matrices

Compact High-Velocity Atmospheric Pressure Dielectric Barrier Plasma Jet in Ambient Air

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2015年第1期17卷 14-19页

作者： Annette MEINERS Michael LECK Bernd abel University of Applied Science and Arts Department of Science and Technology Leibniz-Institut für Oberflachenmodifizierung(IOM) Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie Universitat Leipzig

In this paper,a non-thermal atmospheric pressure plasma jet at high streaming velocity operating with ambient air is *** the present technological approach,the employment of air poses a significant *** high oxygen concentration in air results in a reduced concentration of reactive species in combination with a short species *** plasma jet assembly presented here contains a special dielectric barrier with a high secondary emission *** this way,the electron density and in turn the density of reactive species is *** addition,the plasma jet assembly is equipped with a short *** leads to a higher voltage across the discharge gap and in turn to an increased density of reactive plasma *** plasma jet is formed within and emitted by a small conical nozzle.A high-speed gas flow with gas velocity of 340 m/s was achieved at the end of the *** the jet the concentration of toxic and unwanted neutral plasma species like O3 or NOx is significantly reduced because of the shorter residence time within the *** range of short-lived active plasma species is in turn considerably *** jet efficiency and action range measured through the oxidation of a test surface were determined by measuring the increase of surface tension of a polypropylene substrate via contact angle measurements after plasma *** modeling of the plasma plume indicates that oxygen atoms are in fact the main active species in the plasma plume.

关键词： plasma jet atmospheric plasma dielectric barrier radicals plasma modeling

A new species of Atelopus(Amphibia:Bufonidae)from eastern Panama

在线全文

学校读者我要写书评

暂无评论

Zoological Research 2021年第3期42卷 272-279页

作者： Milan Vesely abel Batista Department of Zoology Faculty of Natural SciencesPalacky UniversityOlomouc 77146Czech Republic Universidad Autónoma de Chiriquí Ciudad Universitaria El Cabrero DavidChiriquí427Panama Asociacion ADOPTA el Bosque Panamá Gamboa 119xPanama Fundacion Los Naturalistas DavidChiriquí426-01459Panama

A new species of the genus Atelopus,Atelopus fronterizo ***.,from eastern Panama is described herein based on molecular,morphological,and bioacoustic *** new species can be distinguished from its congeners occurring in the region by a combination of the following characters:(1)phalangeal reduction in thumb;(2)SVL(females only)(35.1-50.1;n=13),HW/SVL(0.23-0.34;n=59),EYND/HW(0.27-0.39;n=60),TIBL/SVL(0.41-0.56;n=58),and HAL/SVL(0.22-0.28;n=49);(3)dorsal color pattern with green or yellow background and extensive dark olive blotches forming transversal bands or mottling;(4)advertisement call duration 176-235 ms with 19-34 pulses,average pulse rate 131.69 pulses/s,and dominant frequency 2422.50-2606.50 *** new species is nested within the Central American clade of *** minimum Kimura‐2‐parameter(K2P)genetic divergence between Atelopus fronterizo *** its most phylogenetically similar congeners(*** and ***)is>2.6%for 16S and>4.9%for COI(Table 1).The phylogenetic relationship is strongly supported by ultrafast bootstrap values for the maximum-likelihood trees of both genetic markers(16S,96;COI,100,Figure 1A).Bayesian analysis of the concatenated sequences resulted in a tree with similar topology and high posterior probability support(0.99;Supplementary Figure S1).In addition,haplotype networks inferred from COI and 16S(Supplementary Figure S2)showed a well-separated clade containing the new species(two for COI,four for 16S).

关键词： 16S Figure eastern

The nature of the companion of PSR J1719-1438: a white dwarf or an exotic object?

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2012年第7期12卷 813-816页

作者： J. E. horvath Instituto de Astronomia Geofísica e Ciências Atmosfricas - Universidade de So Paulo

We raise the possibility that the very dense, compact companion of PSR J1719-1438, which has a Jupiter-like mass, is an exotic quark object rather than a light helium or carbon white dwarf. The exotic hypothesis naturally explains some of the observed features, and provides quite strong predictions for this system, to be confirmed or refuted in feasible future studies.

关键词： binary pulsars -- exotic matter-- pulsars: individual (PSR J1719-1438)

Purification of solar cell silicon materials through filtration

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2006年第z1期25卷 180-185页

作者： CIFTJA Arjan ENGH Thorvald abel KVITHYLD Anne Department of Materials Science and Engineering Norwegian University of Science and Technology Trondheim N-7491 Norway

Silicon is the material most commonly used in the manufacturing of photovoltaic (PV) cells. In the current study, laboratory experiments of purification of solar cell silicon materials through filtration are carried out. Inclusion removal from silicon was investigated. The purpose is to achieve clean silicon materials for solar cells. Silicon samples and filter samples were analyzed using microscope observation, EPMA, and X-ray detection. Silicon nitride (Si3N4) and silicon carbide (SiC) particles are the main non-metallic inclusions present in top-cut silicon scrap. Almost all inclusions larger than 10 μm can be removed from silicon by the porous foam filter. In mass fraction, more than 90% inclusions are removed. Si3N4 particles are mainly removed on the top surface of the filter, and SiC particles are mainly removed by entering the pores and attaching to the filter material. SiC inclusions are not only simply attached on the surface of the filter material, but are found also inside the filter material. There are SiC bridges near the filter materials. These bridges may fill the spaces between filter material, and this will further retard inclusions passing through the filter. Three-dimensional turbulent fluid flow and inclusion motion in the filter was calculated. Both experimental observation and fluid flow simulation indicate that most of the inclusions are entrapped at the upper part of the filter.

关键词： solar cell silicon inclusions filtration nitrides carbides fluid flow

Model of acceptance of Web 2.0 technologies for increased participation in learning activities A case study of a Scottish university

在线全文

学校读者我要写书评

暂无评论

International Journal of Intelligent Computing and Cybernetics 2015年第3期8卷 208-221页

作者： abel Usoro Razep Echeng University of the West of Scotland PaisleyUK

Purpose–The purpose of this paper is to find out how to encourage the use of Web 2.0 in learning in higher education by investigating factors that would relate to and would encourage such ***/methodology/approach–Three existing theories of technology acceptance underpinned this research and six constructs selected from these existing theories and one new construct from a pilot study were used to develop a conceptual model which constructs were operationalized into an online questionnaire(open and closed ended questions).Copies of this questionnaire were electronically distributed to all students in a higher institution of learning in *** total,203 *** and regression analyses were performed on the quantitative data collected so as to validate the research model.A focus group of ten volunteer students provided opportunity for a follow-up interview that produced in-depth information which provided strategies for enhancing the use of Web 2.0 tools for learning in higher ***–All the factors of the model,except perceived ease of use,positively relate significantly with use *** factors are perceived usefulness,facilitating conditions,motivation,prior knowledge,performance expectancy and social *** limitations/implications–The study was performed at only one institution in *** implication of the study is that predictor variables(mentioned above in the findings)of the model should be taken into consideration when introducing Web 2.0 to students of higher *** implications–In the paper are discussed specific strategies and these include assigning roles to users with little participation,checking to ensure irregular users have access and e-mailing them to encourage ***/value–This is apparently the first time the key technology acceptance models have been synthesised and tested in Scotland with regards to the acceptance of Web 2.0 tools in learning in higher

关键词： Web 2.0 e-Learning Technology acceptance Higher education Scottish university Learning participation

Geomorphic investigations in the Medves Area,North Hungary

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 Science Bulletin 2001年第S1期46卷 57-61页

作者： horvath Gergely Pinter Zolten Department of Geography Teachers Training FacultyEotviis Lorand UniversityH-1397 BudapestPf.514.Hungary

The Medves Area lies close to the Hungarian-Slovak boundary in North Hungary. Having 'horst-graben-type' geological structure it can be characterised by steeply emerging horst-like hills and between them narrow trenches and deeply dissected erosional valleys. The recent morphology of the Medves Area is determined by four main elements: the structure, the petrographic setting, the exo-genic processes and the anthropogenic effects. In spite of the domination of the Oligocene-Miocene sedimentary rocks great part of the area is covered by Pliocene basalts having either stratovolcanic structure or consisting of only lavas, forming lavaplateaus, small cones, dykes or necks. In spite of the strong denudation their original form dominates yet. The decrease of the sheet of the Medves Plateau was considerable only on the rims by parallel retreat. In the southern part of the Medves Area the evolution of the landscape was determined mainly by exogenic processes. The great density of the valleys is very significant,

关键词： geomorphology volcanism Hungary.