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Modal Decomposition for the Analysis of the Rotor-stator Interactions in Multi-stage Compressors

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Journal of Thermal Science 2012年第3期21卷 276-285页

作者： n.Courtiade X.Ottavy n.Gourdain Laboratoire de Mécanique des Fluides et d'Acoustique Ecole Centrale de Lyon CERFACS CFD Team

A modal analysis method of the rotor-stator interactions in multistage compressors has been developed by LMFA. This method, based on a double modal decomposition of the flow over space and time, has been applied to nu- merical and experimental results of the high-speed 3Y2-stage compressor CREATE based at LMFA, Lyon-France. It reveals the presence of a very strong rotor-stator interaction which completely drives the flow at casing behind all the rotors. This modal analysis method applied to an unsteady RAnS simulation permits to calculate the en- ergy of the rotor-stator interactions and to plot energetic meridian maps to explain experimental results and to analyze the interaction in the whole machine.

关键词： rotor-stator interactions modal analysis multistage compressors numerical and experimental results

Compression properties of cost-efficient porous expanded clay reinforced AA7075 syntactic foams fabricated by industrial-oriented die casting technology

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China Foundry 2024年第1期21卷 60-70页

作者： İsmail Cem Akgün Çağın Bolat Ali Gökşenli Faculty of Mechanical Engineering Istanbul Technical University34437İstanbulTurkey Faculty of Engineering Samsun University55420SamsunTurkey

In today’s manufacturing industries,hard competition between rival firms makes it compulsory for researchers to design lighter and cheaper machine components due to the megatrends of cost-effectiveness and *** this point,aluminum syntactic foams(ASFs)are new-generation engineering composites and come into the upfront as a *** to their features like low density,sufficient elongation,and perfect energy absorption ability,these advanced foams have been considerably seductive for many industrial sectors *** this study,an industrial-oriented automatic die casting technology was used for the first time to manufacture the combination of AA7075/porous expanded clay(PEC).Micro evaluations(optical and FESEM)reveal that there is a homogenous particle distribution in the foam samples,and inspections are compatible with the other ASF ***,T6 aging heat treatment was operated on one half of the produced foams to explore the probable impact of aging on the compressive *** results show that PEC particles can be an alternative to expensive hollow spheres used in the previous ***,a favorable relationship is ascertained between the aging treatment and mechanical properties such as compression strength and plateau strength.

关键词： die casting porous materials metal matrix sytanctic foams expanded clay compressive deformation

ERROR ESTIMATES FOR THE TIME DISCRETIZATIOn FOR nOnLInEAR MAXWELL'S EQUATIOnS

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Journal of Computational Mathematics 2008年第5期26卷 677-688页

作者： Mavián Slodika Ján Bua Jr. Department of Mathematical Analysis Ghent University

This paper is devoted to the study of a nonlinear evolution eddy current model of the type δtB（H）＋ △↓× （ △↓ × H） =0 subject to homogeneous Dirichlet boundary conditions H × v = 0 and a given initial datum. Here, the magnetic properties of a soft ferromagnet are linked by a nonlinear material law described by B（H）. We apply the backward Euler method for the time discretization and we derive the error estimates in suitable function spaces. The results depend on the nonlinearity of B（H）.

关键词： Electromagnetic field nonlinear eddy current problem Time discretization,Error estimate.

Travel time prediction with viscoelastic traffic model

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Applied Mathematics and Mechanics(English Edition) 2018年第12期39卷 1769-1788页

作者： Yongliang ZHAnG M.n.SMIRnOVA A.I.BOGDAnOVA Zuojin ZHU n.n.SMIRnOV Faculty of Engineering Science University of Science and Technology of China Faculty of Mechanics and Mathematics Moscow M.V.Lomonosov State University Scientific Research Institute for System Analysis Russian Academy of Sciences

Travel time through a ring road with a total length of 80 km has been predicted by a viscoelastic traffic model(VEM), which is developed in analogous to the non-newtonian fluid flow. The VEM expresses a traffic pressure for the unfree flow case by space headway, ensuring that the pressure can be determined by the assumption that the relevant second critical sound speed is exactly equal to the disturbance propagation speed determined by the free flow speed and the braking distance measured by the average vehicular length. The VEM assumes that the sound speed for the free flow case depends on the traffic density in some specific aspects, which ensures that it is exactly identical to the free flow speed on an empty road. To make a comparison, the open navier-Stokes type model developed by Zhang(ZHAnG, H. M. Driver memory, traffic viscosity and a viscous vehicular traffic flow model. Transp. Res. Part B, 37, 27–41(2003)) is adopted to predict the travel time through the ring road for providing the counterpart *** the traffic free flow speed is 80 km/h, the braking distance is supposed to be 45 m,with the jam density uniquely determined by the average length of vehicles l ≈ 5.8 m. To avoid possible singular points in travel time prediction, a distinguishing period for time averaging is pre-assigned to be 7.5 minutes. It is found that the travel time increases monotonically with the initial traffic density on the ring road. Without ramp effects, for the ring road with the initial density less than the second critical density, the travel time can be simply predicted by using the equilibrium speed. However, this simpler approach is unavailable for scenarios over the second critical.

关键词： travel time viscoelastic modeling distinguishing period for time averaging spatial-temporal pattern traffic jam

Rheological and tribological approaches as a tool for the development of sustainable lubricating greases based on nano-montmorillonite and castor oil

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Friction 2021年第2期9卷 415-428页

作者： Jose Enrique MARTÍn-ALFOnSO María Jose MARTÍn-ALFOnSO Concepción VALEnCIA María Teresa CUBERES Department of Chemical Engineering and Materials Science Campus de“El Carmen”University of HuelvaChemical Product and Process Technology Research Center(Pro2TecS)Huelva 21071Spain Department of Applied Mechanics and Project Engineering University of Castilla-La ManchaAlmadén 13400Spain

This study investigates the development of novel montmorillonite/castor oil blends to formulate sustainable lubricating greases to promote the replacement of petrochemicals industry-derived materials by substances obtained from renewable ***,the effect of the thickener concentration on the rheological,chemical,thermal,tribological properties,and atomic force microscopy(AFM)microstructure of these systems were *** results showed that the C20A nanoclay content could be used to modulate the viscosity values,the linear viscoelastic functions,and tribological properties of these montmorillonite *** general,these gel-like dispersions exhibited remarkable lubricant properties;the samples showed values of the friction coefficient and wear scars similar or lower than those obtained with model bentonite grease.

关键词： lubricating greases nanoclay vegetable oil rheology tribology

Remarks on “A new non-specificity measure in evidence theory based on belief intervals”

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Chinese Journal of Aeronautics 2018年第3期31卷 529-533页

作者： Joaquín ABELLAn Department of Computer Science and Artificial Intelligence University of Granada

Two types of uncertainty co-exist in the theory of evidence： discord and *** 90s, many mathematical expressions have arisen to quantify these two parts in an *** important aspect of each measure presented is the verification of a coherent set of *** non-specificity, so far only one measure verifies an important set of those properties. Very recently, a new measure of non-specificity based on belief intervals has been presented as an alternative measure that quantifies a similar set of properties（Yang et al., 2016）. It is shown that the new measure really does not verify two of those important properties. Some errors have been found in their corresponding proofs in the original publication.

关键词： Additivity Imprecise probabilities non-specificity Subadditivity Theory of evidence Uncertainty measures

Study on Detection of negative Corona Discharge Generated in Rod-Plane Air Gap by Using External Electrode Method

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Plasma Science and Technology 2007年第6期9卷 686-689页

作者： n.ICHIKAWA national Institute of Occupational Safety and Health(JnIOSH) Electrical Safety Research Group1-4-6UmezonoKiyoseTokyo 204-0024Japan

A detective method of a negative corona discharge by means of an external electrode is presented. The relationship between an area of the external electrode and a detected voltage waveform is examined experimentally. This experimental study is carried out with the use of a rod-plane air gap. The results obtained will be applicable to problems associated with silos, ducts, and high-voltage equipment.

关键词： external detection of corona discharges external electrode method (EEM),prevention of accidents

Absorption of laser radiation in ultracold plasma

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Chinese Physics B 2016年第10期25卷 128-131页

作者： n Y Shaparev Institute of Computational Modeling Russian Academy of Sciences national Research Tomsk State University

In this paper, we analyze the spectral behavior(optical thickness, shape and linewidth) of laser radiation absorption under the correlation heating of ions in an ultracold plasma. The Voigt formula is used to find the absorption *** spectral line width is shown to grow with time while the optical thickness reduces. Our modeling results are in good agreement with the experimental findings reported in the literature.

关键词： absorption laser radiation ultracold plasma

On a Question of the Theory of Partially Composition Formations（Dedicated to Professor K.P. Shum on the occasion of his 70th birthday）

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Algebra Colloquium 2014年第3期21卷 437-447页

作者： A.A. Tsarev n.n. Vorob'ev Department of Mathematics P.M. Masherov Vitebsk State University Vitebsk 210038 Belarus Department of Mathematics F. Skorina Gomel State University Gomel' 246019 Belarus

Let n 〉 0 and w be a non-empty set of primes. It is proved that the lattice of all τ-closed n-multiply ω-composition formations is inductive. It gives a positive answer to a question of Skiba asked in 2001 at the G... 详细信息

关键词： finite group formation of groups ω-composition satellite of formation,τ -closed n-multiply ω-composition formation inductive lattice of formations