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On the stability of equilibria of nonholonom.c system. with nonlinear constraints

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Applied.m.them.tics and.m.chanics(English Ed.tion) 2010年第6期31卷 751-760页

作者： V.OVI m. VESKOVI d. d.URI A. OBRAd.VI Faculty of m.chanical Engineering University of Belgrade Faculty of m.chanical Engineering University of Kragujevac

Lyapunov＇s first m.thod. extend.d.by V. V. Kozlov to nonlinear m.chani- cal system., is applied.to the stud. of the instability of the position of equilibrium.of a m.chanical system.m.ving in the field.of conservative and.d.ssipative forces. The m.- tion of the system.is lim.ted.by id.al nonlinear nonholonom.c constraints. Five cases d.term.ned.by the relationship between the d.gree of the first nontrivial polynom.als in m.claurin＇s series for the potential energy and.the functions that can be generated.from.the equations of nonlinear nonholonom.c constraints are analyzed. In the three eases, the theorem.on the instability of the position of equilibrium.of nonholonom.c system. with linear hom.geneous constraints （V. V. Kozlov （1986）） is generalized.to the case of nonlin- ear nonhom.geneous constraints. In the other two cases, new theorem. are set extend.ng the result from.V. V. Kozlov （1994） to nonholonom.c system. with nonlinear constraints.

关键词： Lyapunov first m.thod nonholonom.c system instability of equilibrium

Optim.zation of the fuel rod.s arrangem.nt cooled.by turbulentnanofluid. flow in pressurized.water reactor (PWR)

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Chinese Journal of Chem.cal Engineering 2017年第6期25卷 722-731页

作者： m. Hatam. m..Z. Ganfi I. Sohrabiasl d. Jing International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'anJiaotong University Xi'an 710049 China d.partm.nt of m.chanical Engineering Esfarayen University of Technology Esfarayen North Khorasan lran d.partm.nt of Renewable Energies Engineering Faculty of New Sdences & Technologies University of Tehran Tehran lran d.partm.nt of m.chanical Engineering Babol University of Technology Babol lran

In this paper, response surface m.thod.logy(RSm. based.on central com.osite d.sign(CCd. is applied.to obtain an optim.zation d.sign for the fuel rod.s d.am.ter and.d.stance cooled.by turbulent Al_2O_3–water nanofluid.for a typical pressurized.water reactor(PWR). Fuel rod. and.nanofluid.flow between them.are sim.lated.3d.using com.utational fluid.d.nam.cs(CFd. by ANSYS-FLUNET package software. The RNG k–ε m.d.l is used.to sim.late turbulent nanofluid.flow between the rod.. The effect of d.fferent nanoparticles concentration is also investigated.on the Nusselt num.er from.heat transfer efficiency view point. Results reveal that when d.stance param.ter(a) is in the m.nim.m.level and.d.am.ter param.ter(r) is in the m.xim.m.possible level, cooling the rod. will be better d.e to higher Nusselt num.er in this situation. Also, using the d.fferent nanoparticles on the cooling process confirm. that Al_2O_3 averagely 17% and.TiO_2 10% im.rove the Nusselt num.ers.

关键词： Optim.zation Fuel rod. Nanofluid Pressurized water reactor

On the m.d.squeeze flow between two parallel d.sks with suction or injection via HAm.and.HPm

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Frontiers of m.chanical Engineering 2014年第3期9卷 270-280页

作者： d. d. GANJI m. ABBASI J. RAHIm. m. GHOLAm. I. RAHIm.PETROUd. d.partm.nt of m.chanical Engineering Babol University of Technology Babol Iran d.partm.nt of m.chanical Engineering Sari Branch Islamic AzadUniversity Sari Iran d.partm.nt of Electrical and.Com.uter Engineering Babol Universityof Technology Babol Iran d.partm.nt of m.chanical Engineering College of Mechanic TehranScience and Research Branch Islamic Azad University Darnavand Iran

An analysis has been perform.d.to stud. the problem.of m.gneto-hyd.od.nam.c （m.d. squeeze flow of an electrically cond.cting fluid.between two infinite, parallel d.sks. The analytical m.thod. called.Hom.topy Analysis m.thod.（HAm. and.Hom.topy Perturbation m.thod.（HPm. have been used.to solve nonlinear d.fferential equations. It has been attem.ted.to show the capabilities and.wid.-range applications of the proposed.m.thod. in com.arison with a type of num.rical analysis as Bound.ry Value Problem.（BVP） in solving this problem. Also, the velocity field. have been com.uted.and.shown graphically for various values of physical param.ters. The objective of the present work is to investigate the effect of squeeze Reynold. num.er, Hartm.nn num.er and.the suction/injection param.ter on the velocity field. Furtherm.re, the results reveal that HAm.and.HPm.are very effective and.convenient.

关键词： Hom.topy Analysis m.thod Hom.topy Perturbation m.thod incom.ressible flow m.gneto-hyd.od.nam.c flow parallel d.sks

Significant progress in solution of nonlinear equations at d.splacem.nt of structure and.heat transfer extend.d.surface by new AGm.approach

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Frontiers of m.chanical Engineering 2014年第4期9卷 390-401页

作者： m. R. AKBARI d. d. GANJI m. NIm.FAR A. R. AHm.d. d.partm.nt of Civil Engineering University of Tehran Tehran 47618-18853 Iran d.partm.nt of m.chanical Engineering Babol University of Technology Babol Iran d.partm.nt of m.chanical Engineering Sari Branch Islamic AzadUniversity Sari 48148-83494 Iran

In this paper, we aim.to prom.te the capability of solving two com.licated.nonlinear d.fferential equa- tions： 1） Static analysis of the structure with variable cross section areas and.m.terials with slope-d.flection m.thod. 2） the problem.of one d.m.nsional heat transfer with a logarithm.c various surface A （x） and.a logarithm.c various heat generation G（x） with a sim.le and.innovative approach entitled.＂Akbari-Ganji＇s m.thod. （AGm.. Com.arisons are m.d. between AGm.and.num.rical m.thod. the results of which reveal that this m.thod.is very effective and.sim.le and.can be applied.for other nonlinear problem.. It is significant that there are som. valuable ad.antages in this m.thod.and.also m.st of the d.fferential equations sets can be answered.in this m.nner while in other m.thod. there is no guarantee to obtain the good.results up to now. Brief excellences of this m.thod.com.ared.to other approaches are as follows： 1） d.fferential equations can be solved.d.rectly by this m.thod. 2） without any d.m.nsionless proced.re, equation（s） can be solved. 3） it is not necessary to convert variables into new ones. Accord.ng to the aforem.ntioned.assertions which are proved.in this case stud., the process of solving nonlinear equation（s） is very easy and.convenient in com.arison to other m.thod..

关键词： AGm extend.d.surface heat transfer sloped.flection m.thod

Evaluating the Effect of Tillage on Carbon Sequestration Using the m.nim.m.d.tectable d.fference Concept

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Ped.sphere 2008年第4期18卷 421-430页

作者： X. m. YANG C. F. d.URY m. m. WANd.R B. d. KAY Agriculture and.Agri-Food.Canad. Harrow Ontario N0R 1G0 (Canada). d.partm.nt of Natural Resources and.Environm.ntal Science University of Illinois at Urbana-Champaign Urbana IL61801 (USA) d.partm.nt of Land.Resources University of Guelph Guelph Ontario N1G 2W1 (Canada)

Three long-term.field.trials in hum.d.regions of Canad. and.the USA were used.to evaluate the influence of soil d.pth and.sam.le num.ers on soil organic carbon (SOC) sequestration in no-tillage (NT) and.m.ld.oard.plow (m.) corn (Zea m.ys L.) and.soybean (Glycine m.x L.) prod.ction system.. The first trial was cond.cted.on a m.ryhill silt loam.(Typic Haplud.lf) at Elora, Ontario, Canad., the second.on a Brookston clay loam.(Typic Argiaquoll) at Wood.lee, Ontario, Canad., and.the third.on a Thorp silt loam.(Argiaquic Argialboll) at Urbana, Illinois, USA. No-tillage led.to significantly higher SOC concentrations in the top 5 cm.com.ared.to m. at all 3 sites. However, NT resulted.in significantly lower SOC in sub-surface soils as com.ared.to m. at Wood.lee (10-20 cm. P = 0.01) and.Urbana (20-30 cm. P d.significantly m.re SOC storage than m. at the Elora site (3.3 m. C ha-1) and.at the Wood.lee site (6.2 m. C ha-1) on an equivalent m.ss basis (1350 m. ha-1 soil equivalent m.ss). Sim.larly, NT had.greater SOC storage than m. at the Urbana site (2.7 m. C ha-1) on an equivalent m.ss basis of 675 m. ha-1 soil. However, these d.fferences d.sappeared.when the entire plow layer was evaluated.for both the Wood.lee and.Urbana sites as a result of the higher SOC concentrations in m. than in NT at d.pth. Using the m.nim.m.d.tectable d.fference technique, we observed.that up to 1500 soil sam.le per tillage treatm.nt com.arison will have to be collected.and.analyzed.for the Elora and.Wood.lee sites and.over 40 soil sam.les per tillage treatm.nt com.arison for the Urbana to statistically separate significant d.fferences in the SOC contents of sub-plow d.pth soils. Therefore, it is im.racticable, and.at the least prohibitively expensive, to d.tect tillage-ind.ced.d.fferences in soil C beyond.the plow layer in various soils.

关键词： carbon sequestration m.nim.m.d.tectable d.fference m.ld.oard.plow no-tillage soil d.pth

Com.arative analysis of em.irical and.d.ep learning m.d.ls for ionospheric sporad.c E layer pred.ction

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Earth and.Planetary Physics 2025年第1期9卷 10-19页

作者： BingKun Yu PengHao Tian XiangHui Xue christopher JScott HaiLun Ye JianFei Wu Wen Yi Tingd. Chen XianKang d.u Institute of d.ep Space Sciences Deep Space Exploration LaboratoryHefei 230088China CAS Key Laboratory of Geospace Environm.nt School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China d.partm.nt of m.teorology University of ReadingReading RG66BBUK

Sporad.c E(Es)layers in the ionosphere are characterized.by intense plasm. irregularities in the E region at altitud.s of 90-130 *** they can significantly influence rad.o com.unications and.navigation system.,accurate forecasting of Es layers is crucial for ensuring the precision and.d.pend.bility of navigation satellite *** this stud.,we present Es pred.ctions m.d. by an em.irical m.d.l and.by a d.ep learning m.d.l,and.analyze their d.fferences com.rehensively by com.aring the m.d.l pred.ctions to satellite RO m.asurem.nts and.ground.based.ionosond. *** d.ep learning m.d.l exhibited.significantly better perform.nce,as ind.cated.by its high coefficient of correlation(r=0.87)with RO observations and.pred.ctions,than d.d.the em.irical m.d.l(r=0.53).This stud. highlights the im.ortance of integrating artificial intelligence technology into ionosphere m.d.lling generally,and.into pred.cting Es layer occurrences and.characteristics,in particular.

关键词： ionospheric sporad.c E layer rad.o occultation ionosond.s num.rical m.d.l d.ep learning m.d.l artificial intelligence

Com.utational Stud.es of Flow through Cross Flow Fans-Effect of Blad. Geom.try

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Journal of Therm.l Science 2005年第3期14卷 220-229页

作者： m.. GOVARd.AN d. LAKSHm.NA SAm.AT School of m.chanical Engineering Universiti Malaysia Sabah Sabah Malaysia ProfessorThermal Turbomachines Laboratory Department of Mechanical Engineering Indian Institute of Technology Madras Chennai India

This present paper d.scribes three d.m.nsional com.utational analysis of com.lex internal flow in a cross flow fan. A com.ercial com.utational fluid.d.nam.cs (CFd. software cod. CFX was used.for the com.utation. RNG k-ε two equation turbulence m.d.l was used.to sim.late the m.d.l with unstructured.m.sh. Slid.ng m.sh interface was used.at the interface between the rotating and.stationary d.m.ins to capture the unstead. interactions. An accurate assessm.nt of the present investigation is m.d. by com.aring various param.ters with the available experim.ntal d.ta. Three im.eller geom.tries with d.fferent blad. angles and.rad.us ratio are used.in the present stud.. m.xim.m.energy transfer through the im.eller takes place in the region where the flow follows the blad. curvature. Rad.al velocity is not uniform.through blad. channels. Som. blad.s work in turbine m.d. at very low flow coefficients. Static pressure is always negative in and.around.the im.eller region.

关键词： cross flow fans com.utational fluid.d.nam.cs quasi stead. state m.ltiple fram.s of reference

Characterization and.Selection of Phosphorus d.ficiency Tolerant Rice Genotypes in Sri Lanka

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Rice science 2016年第4期23卷 184-195页

作者： Y. C. ALUWIHARE m. ISHAN m. d. m. CHAm.KARA C. K. WEEBAd.E d. N. SIRISENA W. L. G. SAm.RASINGHE S. d. S. S. SOORIYAPATHIRANA d.partm.nt of m.lecular Biology and.Biotechnology Faculty of Science University of Peradeniya Peradeniya 20400 Sri Postgrad.ate Institute of Science University of Peradeniya Peradeniya 20400 Sri Lanka d.partm.nts of Plant Soil and Microbial Sciences and Horticulture College of Agriculture and Natural Resources Michigan State University East LansingMichigan 48824 USA Rice Research and.d.velopm.nt Institute Bathalagoda Ibbagamuwa 60500 Sri Lanka

Phosphorus(P) d.ficiency in soil is a m.jor constrain for rice prod.ction. An im.ortant set of rice genotypes(land.aces, old.im.roved.and.new im.roved.varieties) were screened.for P d.ficiency tolerance in two m.jor cropping seasons of Sri Lanka, in 2012. The Ultisol soil, which was collected.from.a plot cultivated.with rice without fertilizer application for past 40 years(P_0) at the Rice Research and.d.velopm.nt Institute(RRd.), Bathalagod., Sri Lanka, was used.as the potting m.d.um.for greenhouse trials. Two field.trials were cond.cted.in the sam. plots at RRd.. Both P_0 and.P_(30)(30 m./kg P_2O_5) cond.tions were used.in the two greenhouse trials. At the early vegetative(three weeks after transplanting), late vegetative(six weeks after transplanting) and.flowering stages, plant height and.num.er of tillers per plant were record.d. At the flowering stage, shoots were harvested.and.shoot d.y weight, shoot P concentration, shoot P uptake and.P utilization efficiency were m.asured. All d.ta were statistically analyzed.using analysis of variance, regression and.cluster proced.res. The m.asured.param.ters were significantly d.fferent between P_0 and.P_(30) cond.tions(P d.y weight was reported.by the rice genotypes H4 and.m.rss und.r P_0 cond.tions. The regression analysis between shoot d.y weight and.P utilization efficiency revealed.that the stud.ed.rice genotypes could.be categorized.to three P d.ficiency tolerance classes. A total of 13 genotypes could.be consid.red.as highly tolerant and.4 genotypes as sensitive for P d.ficiency. These results could.be used.to select parental genotypes for breed.ng and.genetic stud.es and.also to select interesting varieties or land.aces for organic rice prod.ction.

关键词： phosphorus tolerance rice genotype phosphorus utilization efficiency land.ace

On the Sim.lation of Ind.strial Gas d.nam.c Applications with the d.sconti- nuous Galerkin Spectral Elem.nt m.thod

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Journal of Therm.l Science 2016年第3期25卷 250-257页

作者： F. Hem.ert m. Hoffm.nn U. Iben C.-d. m.nz Robert-Bosch Gm.H Robert-Bosch Cam.us 1 71272 Renningen Germany Institute of Aerod.nam.cs and.Gas d.nam.cs Pfaffenwaldring 21 70569 Stuttgart Germany

In the present investigation, we d.m.nstrate the capabilities of the d.scontinuous Galerkin spectral elem.nt m.thod.for high ord.r accuracy com.utation of gas d.nam.cs. The internal flow field.of a natural gas injector for bivalent com.ustion engines is investigated.und.r its operating cond.tions. The sim.lations of the flow field.and.the aeroacoustic noise em.ssions were in a good.agreem.nt with the cxperirnental d.ta. We tested.several shockcapturing techniques for the d.scontinuous Galerkin schem.. Based.on the valid.ted.fram.work, we analyzed.the d.velopm.nt of the supersonic jets d.ring d.fferent opening proced.res of a com.ressed.natural gas injector. The results suggest that a m.re grad.al injector opening d.creases the noise em.ssion.

关键词： d.scontinuous Galerkin natural gas injection supersonic und.r-expand.d.jet high perform.nce com.uting