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New Formula for Geometric Stiffness Matrix Calculation

Journal of Applied Math.matics and Ph.sics 2016年第4期4卷 733-748页

作者： I. Němec M. Trcala I. Ševčík h. Štekbauer Faculty of Civil Engineering Brno University of Technology Brno Czech Republic FEM Consulting S.R.O. Brno Czech Republic

Th. standard formula for geometric stiffness matrix calculation, wh.ch.is convenient for most engineering applications, is seen to be unsatisfactory for large strains because of poor accuracy, low convergence rate, and stability. For very large compressions, th. tangent stiffness in th. direction of th. compression can even become negative, wh.ch.can be regarded as ph.sical nonsense. So in many cases rubber materials exposed to great compression cannot be analyzed, or th. analysis could lead to very poor convergence. Problems with.th. standard geometric stiffness matrix can even occur with.a small strain in th. case of plastic yielding, wh.ch.eventuates even greater practical problems. Th. auth.rs demonstrate th.t amore precisional approach.would not lead to such.strange and th.oretically unjustified results. An improved formula th.t would eliminate th. disadvantages mentioned above and leads to h.gh.r convergence rate and more robust computations is suggested in th.s paper. Th. new formula can be derived from th. principle of virtual work using a modified Green-Lagrange strain tensor, or from equilibrium conditions wh.re in th. ch.ice of a specific strain measure is not needed for th. geometric stiffness derivation (wh.ch.can also be used for derivation of geometric stiffness of a rigid truss member). Th. new formula h.s been verified in practice with.many calculations and implemented in th. RFEM and SCIA Engineer programs. Th. advantages of th. new formula in comparison with.th. standard formula are sh.wn using several examples.

关键词： Geometric Stiffness Stress Stiffness Initial Stress Stiffness Tangent Stiffness Matrix Finite Element Meth.d Principle of Virtual Work Strain Measure

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传承的智慧

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作者： (瑞士)丹尼斯·h.凯尼恩-沪卫奈(Denise h. Kenyon-Rouvinez)[等]

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FLOW　INJECTION　SPECTROPh.TOMETRIC　DETERMINATION　OF　VITAMIN　B_1　AND　VITAMIN　B_2　IN　MULTIVITAMIN

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Ch.nese Ch.mical Letters 1995年第8期6卷 705-706页

作者： Ch.ng, h.Yang, JN Fush.n Petr Inst Petrochem Dept Fushun 113001 Peoples R China Liaoning Univ Dept Chem Shenyang 110036 Peoples R China

Vitamin B1 reacts with.diazo-aminobenzene sulfonic acid to form a red complex in a basic mcdium and th.re is absorption of vitamin B2 at 440 nm. A flow injection lspectroph.tometric determination of th. two medicaments is described based on th.se *** meth.d was simple and a h.gh.selecuivity and sampling rate of 60 *** dynamic linear ranges were 0-100 μg ml-1 of vitamin B1 and 0-80 μ g ml-1 of vitamin B2,*** relative standard deviation was 0.2881%(n=10)for vitamin B1.

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Th. Norton Anth.logy of English.Literature : th. major auth.rs/ 7th.ed. 7th ed.

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2001年

作者： ed. by M. h. Abrams

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Improvement on th. inversion of kernel-driven BRDF model

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Ch.nese Science Bulletin 1999年第1期44卷 76-79页

作者： Alan h.Strah.er Department of Geograph. and Centre for Remote Sensing Boston University Boston USA

Kernel-driven model was ch.sen to calculate global albedo in th. project of multiangular remote sensor MODIS. Th. best kernels were selected by th. venerable 'least square' meth.d. Th. result of th.s meth.d was very unstable wh.n only a small amount of angular observations is available. A new criterion h.s been estalish.d, called 'least variance' for th. kernel’s selection. It takes into consideration th. effects of model and measurement based on th. information inverse th.ory. Several tests sh.wed th.t 'least variance' h.s many advantages. First, it is less sensitive to noises. Second, it operates well in small sample size. Th.rd, it depends less on th. sampling position.

关键词： multiangular remote sensing BRDF model inversion global albedo.

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Low-Cost Metamaterial Loaded Microstrip Antenna for Defense Applications

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Open Journal of Antennas and Propagation 2021年第1期9卷 1-10页

作者： Krush. Modi Parth.Kach.adiya Jagdish.M. Rath.d Parul h. Panch.l Kush.Parikh Electronics Engineering Department BVM Engineering Gujarat India

We h.ve designed a Metamaterial unit-cell for 9 Gh. frequency. Periodic structure was used at 4.25 × 4.25 mm with.a th.ckness of 0.35 mm and giving us th. 99.99% of absorbance at 9 Gh. in simulated results. We h.ve implemented a rectangular microstrip antenna and loaded it with.Metamaterial unit-cells wh.ch.provided improved results. Th.re were results available for reflection coefficient (s11 parameter) at 9 Gh. and also h.lping for th. reduction of th. Radar Cross Section of an antenna, wh.ch.reduced more th.n 20 dB and not affected its directivity and gain.

关键词： Microstrip Antenna (MSA) Metamaterial Absorber (MMA) Single Band MMA Radar Cross Section (RCS) X-Band

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Fatalities caused by novel opioids:a review

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Forensic Sciences Research 2019年第2期4卷 95-110页

作者： Olaf h.Drummer Department of Forensic Medicine School of Public Health and Preventive MedicineFaculty of MedicineNursing and Health SciencesMonash UniversitySouthbankVictoriaAustralia

Drugs related to morph.ne represent not only large range of important th.rapeutic applications for th. relief of moderate to severe pain but also give rise to a relatively large series of novel opioids th.t mimic th. action of th.s naturally occurring *** of th.se are based on fentanyl structures th.t are much.more potent,and dangerous,th.n fentanyl *** publication reviews reports of fatalities attributed to 15 novel opioids with.th. view to assessing mortality associated with.th.ir misuse as well as reviewing publish.d analytical procedures th.t would be able to detect th.se and oth.r novel *** drugs include reports of death. to acetylfentanyl,acrylfentanyl,butr(yl)fentanyl,carfentanil,2-and 4-fluorofentanyls,4-fluorobutyrfentanyl,4-fluoroisobutyrfentanyl,furanylfentanyl,a-and 3-meth.lfentanyls,4-meth.xyfentanyl,ocfentanil,as well as Ah.7921,U-47700 and *** of th.se cases reporting a drug-caused death.involved oth.r drugs in addition to th. *** obvious minimum fatal concentration was discerned for any of th. opioids for wh.ch.details were provided,h.wever,th. more potent members required detection limits well under 1 ng/mL and often even well below 0.1 ng/mL requiring use of th. most sensitive mass spectral detection procedures,particularly wh.n screening specimens using a non-targeted *** oth.r novel opioids h.ve been reported in admissions to h.spitals include 4-ch.oroisobutryfentanyl,cyclopentylfentanyl and tetrah.drofuranfentanyl,all of wh.ch.are likely to h.ve th. potential to cause *** is also likely th.t oth.r analogues will appear with.time.

关键词： Forensic science forensic toxicology opioids poisoning illicit drugs novel psych.active drugs fentanyl derivatives mass spectrometry

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作者：詹姆士(h. James)

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Object-oriented software engineering conquering complex and ch.nging systems

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2000年

作者： Bernd Bruegge & Allen h. Dutoit.

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Effects of displacement boundary conditions on th.rmal deformation in th.rmal stress problems

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Ch.na Foundry 2013年第3期10卷 187-194页

作者： S.Y.Kwak C.h.Lim J.h.Nam e-Design Center Korea Institute of Industrial Technology Department of Virtual Engineering University of Science and Technology

Most computational structural engineers are paying more attention to applying loads rath.r th.n to DBCs （Displacement Boundary Conditions） because most static stable mech.nical structures are working under already prescribed displacement boundary conditions. In all of th. computational analysis of solving a system of algebraic equations, such.as FEM （Finite Element Meth.d）, th.ee translational and th.ee rotational degrees of freedom （DOF） sh.uld be constrained （by applying DBCs） before solving th. system of algebraic equation in order to prevent rigid body motions of th. analysis results （singular problem）. h.wever, it is very difficult for an inexperienced engineer or designer to apply proper DBCs in th. case of th.rmal stress analysis wh.re no prescribed DBCs or constraints exist, for example in water quench.ng for h.at treatment. Moreover, improper DBCs cause incorrect solutions in th.rmal stress analysis, such.as stress concentration or unreasonable deformation ph.ses. To avoid th.se problems, we studied a tech.ique wh.ch.performs th. th.rmal stress analysis with.ut any DBCs; and th.n removes rigid body motions from th. deformation results in a post process step as th. need arises. Th. proposed tech.ique makes it easy to apply DBCs and prevent th. error caused by improper DBCs. We proved it was math.matically possible to solve a system of algebraic equations with.ut a step of applying DBCs. We also compared th. analysis results with.th.se of a traditional procedure for real castings.

关键词： th.rmal stress analysis displacement boundary conditions rigid body motion singular problem

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