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Suitability of lost cores in rheocasting process

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中国有色金属学会会刊：英文版 2010年第S3期20卷 948-953页

作者： H.mICHELS m.büNCK A.büHRIG-POLACZEK Giesserei-Institut RWTH Aachen Intzestraeβ5Aachen 52072Germany

When treated in pressure die casting processes the semi-solid aluminum alloys demand resilient cores which can bear the stress occurring during filling and the final pressure *** design of permanent cores is highly restricted in order to maintain *** cores provide the possibility of complex,undercut geometrical shapes which is mandatory for a variety of casting ***,eligible materials which show appropriate resilience and proper decomposition properties at the same time,and in the upper echelon of cost-effectiveness,are seldom *** the semi-solid process suited between HPDC and GDC regarding the core stress,several common and economically efficient lost core systems could be used.A selection of potentially suitable materials was identified and *** range of testing comprises widespread sand core-systems(amin-pur-coldbox and CO2-water-glass) as well as materials less commonly used,namely salt,plastic and *** types of conditioning are applied to enhance the surface *** mechanical properties of the sand cores are enhanced by different heat treatment methods during *** cores are tested producing a research component cast on a HPDC machine with semi-solid A356 slurry fabricated in the cooling channel *** cast component was analyzed regarding shape stability,core removability and surface as well as the structure *** results show the importance of the surface conditioning for the sand-cores while salt and zinc produce good parts comparable to the reference steel core quality.

关键词： aluminum semi-solid rheocasting cooling channel lost core sand salt zinc plastic

Effects of an Electric Field on the Cylindrical Dust Acoustic Wave in magnetized Complex Plasmas

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Chinese Physics Letters 2012年第7期29卷 184-186页

作者： b.Farokhi m.Eghbali Department of Physics Faculty of ScienceArak UniversityArak 38156-8-8349Iran

Stability of a dust acoustic wave in cylindrical complex plasmas is *** of a static magnetic field (axial) and an electric field (radial) on the propagation of a low frequency wave are *** linear dispersion relations of rotational modes and breathing modes are *** a dusty plasma is confined in a finite region,the void behavior is observed at high speed *** structures of different-mode-number solutions are illustrated.

关键词： wave cylindrical illustrated

Influence of some rock strength properties on jaw crusher performance in granite quarry

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mining Science and Technology 2010年第2期20卷 204-208页

作者： OLALEYE b m Department of mining Engineering Federal University of Technology

The influence of rock strength properties on Jaw Crusher performance was carried out to determine the effect of rock strength on crushing time and grain size distribution of the *** was conducted on four different rock samples namely marble,dolomite,limestone and granite which were representatively selected from fragmented lumps in *** compressive strength and Point load tests were carried out on each rock sample as well as crushing time and size *** results of the strength parameters of each sample were correlated with the crushing time and the grain size distribution of the rock *** results of the strength tests show that granite has the highest mean value of 101.67 mPa for Unconfined Compressive Strength(UCS) test,6.43 mPa for Point Load test while dolomite has the least mean value of 30.56 mPa for UCS test and 0.95 mPa for Point Load *** to the International Society for Rock mechanic(ISRm) standard,the granite rock sample may be classified as having very high strength and dolomite rock sample,low ***,the granite rock has the highest crushing time(21.0 s) and dolomite rock has the least value(5.0 s).based on the results of the investigation,it was found out that there is a great influence of strength properties on crushing time of rock types.

关键词： rock strength jaw crusher crushing time grain size distribution efficiency

The Influence of the magnetic Field on the Electrical breakdown Phenomena

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Plasma Science and Technology 2007年第1期9卷 45-51页

作者： m.RADmILOVI -RADJENOVI b.RADJNOVI Institute of Physics P.O.Box 5711001 BelgradeSerbia Vin a Institute of Nuclear Sciences P.O.Box 522BelgradeSerbia

A simple phenomenological model and detailed simulation studies of the breakdown phenomena in argon and nitrogen under the simultaneous action of electric and magnetic fields are presented in this paper. Expressions for the breakdown voltage have been derived taking into account variations of both the ionization coefficient and the secondary electron yield in a magnetic field. Calculations were performed by using XOOPIC code, an Object Oriented Particle in Cell code, with both the original and the improved secondary emission model with inclusion of the influence of the magnetic field on the secondary electron production. The simulation results presented here clearly show that the inclusion of the dependence of the secondary electron yield on the magnetic field leads to better agreement with existing experimental results.

关键词： breakdown voltage ionization coefficient secondary electron emission simulation technique

Optimal Simultaneous Allocation of Electric Vehicle Charging Stations and Capacitors in Radial Distribution Network Considering Reliability

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Journal of modern Power Systems and Clean Energy 2024年第5期12卷 1584-1595页

作者： b.Vinod Kumar Aneesa Farhan m A the Department of Electrical and Electronic Engineering National Institute of Technology TiruchirappalliTamilnaduIndia

The popularity of electric vehicles(EVs)has sparked a greater awareness of carbon emissions and climate *** mobility expansion and EV adoption have led to an increased infrastructure for electric vehicle charging stations(EVCSs),impacting radial distribution networks(RDNs).To reduce the impact of voltage drop,the increased power loss(PL),lower system interruption costs,and proper allocation and positioning of the EVCSs and capacitors are *** paper focuses on the allocation of EVCS and capacitor installations in RDN by maximizing net present value(NPV),considering the reduction in energy losses and interruption *** a part of the analysis considering reliability,several compensation coefficients are used to evaluate failure rates and pinpoint those that will improve *** locate the best nodes for EVCSs and capacitors,the hybrid of grey wolf optimization(GWO)and particle swarm optimization(PSO)(HGWO_PSO)and the hybrid of PSO and Cuckoo search(CS)(HPSO_CS)algorithms are proposed,forming a combination of GWO,PSO,and CS *** impact of EVCSs on NPV is also investigated in this *** effectiveness of the proposed optimization algorithms is validated on an IEEE 33-bus RDN.

关键词： Electric vehicle charging station optimization radial distribution network vehicle-to-grid loss reduction reliability

Laminar natural convection characteristics in an enclosure with heated hexagonal block for non-Newtonian power law fluids

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Chinese Journal of Chemical Engineering 2017年第5期25卷 555-571页

作者： Krunal m.Gangawane b.manikandan Department of Chemical Engineering College of Engineering StudiesUniversity of Petroleum and Energy Studies

This work illustrates the steady state, two dimensional natural convective flow and heat transfer features in square enclosure containing heated hexagonal block maintained either at constant wall temperature(CWT) or uniform heat flux(UHF) thermal conditions. Governing equations(mass, momentum and energy) are solved by using finite volume method(FVm) with 3rd order accurate QUICK discretization scheme and SImPLE algorithm for range of field pertinent parameters such as, Grashof number(10~3≤ Gr ≤ 10~6), Prandtl number(1 ≤ Pr ≤ 100) and power law index(0.5 ≤ n ≤ 1.5). The analysis of momentum and heat transfer characteristics are delineated by evolution of streamlines, isotherms, variation of average Nusselt number value and Colburn factor for natural convection(j_(nH)). A remarkable change is observed on fluid flow and thermal distribution pattern in cavity for both thermal conditions. Nusselt number shows linear variation with Grashof and Prandtl numbers; while rate of heat transfer by convection decreases for power law index value. Higher heat transfer rate can be achieved by using uniform heat flux condition. A Nusselt number correlation is developed for possible utilization in engineering/scientific design purpose.

关键词： Square cavity Heated block Grashof number Natural convection Power law index

mechanical properties of thixo-formed austempered ductile iron

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中国有色金属学会会刊：英文版 2010年第S3期20卷 798-804页

作者： b.HEIDARIAN m.NLILI-AHmADAbADI m.mORADI School of metallurgy and materials Engineering University of Tehran

Semi-solid processing of metallic materials has been investigated for some time;however,this innovative production process has not fully established for ferrous alloys like ductile cast iron in the industry *** alloys-specially ductile cast ironbecause of increasing complexity due to high temperature processing and some other limitations have been allocated a small share of this useful forming process to ***,this work describes that thixo-forming of ductile iron despite all of the limitations is possible even for thin sections(less than 1 mm).Die temperature and injection velocity are the most effective parameters to thixo-forming particularly for high melting point materials such as ductile cast *** behavior,shape factor of graphites and fluidity of thixo-formed specimens were *** addition,defects as well as shrinkage and cold laps were examined to achieve sound *** to successful thixo-forming,two step austempering was performed to accomplish a uniform structure with minimum untransformed austenite volume(UAV).Following austempering,tensile test was carried out and the results show good combination of tensile strength and elongation for treated specimens(1 137 mPa strength and 12% elongation in best situation).

关键词： semi-solid ductile iron high pressure mold filling segregation mechanical properties

A prediction model for the effective thermal conductivity of nanofluids considering agglomeration and the radial distribution function of nanoparticles

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Acta mechanica Sinica 2018年第3期34卷 507-514页

作者： Z.m.Zheng b.Wang School of Physics Sun Yat-Sen UniversityGuangzhou 510275China Instimt Franco-Chinois de l'Energie Nucleaire Sun Yat-Sen UniversityZhuhai 519000China

Conventional heat transfer fluids usually have low thermal conductivity, limiting their efficiency in many applications. many experiments have shown that adding nanosize solid particles to conventional fluids can greatly enhance their thermal conductivity. To explain this anomalous phenomenon, many theoretical investigations have been conducted in recent years. Some of this research has indicated that the particle agglomeration effect that commonly occurs in nanofluids should play an important role in such enhancement of the thermal conductivity, while some have shown that the enhancement of the effective thermal conductivity might be accounted for by the structure of nanofluids, which can be described using the radial distribution function of particles. However, theoretical predictions from these studies are not in very good agreement with experimental results. This paper proposes a prediction model for the effective thermal conductivity of nanofluids, considering both the agglomeration effect and the radial distribution function of nanoparticles. The resulting theoretical predictions for several sets of nanofluids are highly consistent with experimental data.

关键词： Nanofluid Thermal conductivity modeling Agglomeration Radial distribution function

Practical optimization of deployable and scissor-like structures using a fast GA method

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Frontiers of Structural and Civil Engineering 2019年第3期13卷 557-568页

作者： m.SALAR m.R.GHASEmI b.DIZANGIAN Department of Civil Engineering University of Sistan and BaluchestanZahedanIran Department of Civil Engineering Velayat UniversityIranshahrIran

This paper addresses practical sizing optimization of deployable and scissor-like structures from a new point of *** structures have been recently highly regarded for beauty,lightweight,determine behavior,proper performance against lateral loads and the ability of been compactly *** this time,there is a few studies done considering practical optimization of these *** considered here includes wind and gravity *** foldable scissor-like structures,connections have a complex *** this reason,in this study,the authors used the AbAQUS commercial package as an analyzer in the optimization *** made the obtained optimal solutions highly reliable from the point of view of applicability and construction ***,to do optimization task,a fast genetic algorithm method,which has been recently introduced by authors,was *** results show that despite less weight for aluminum models than steel models,aluminum deployable structures are not affordable because they need more material than steel structures and cause more environmental damage.

关键词： optimization scissor-like structures deployable structures genetic algorithm AbAQUS