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FINITE ELEMENT ANALYSIS OF A VERTICAL RECTANGULAR PLATE COUPLED WITH AN UNBOUNDED FLUID DOMAIN ON ONE SIDE USING A TRUNCATED FAR BOUNDARY

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Journal of Hydrodynamics 2009年第2期21卷 190-200页

作者： PANI P. k. BHATTACHARYYA S. k. Civil Engineering Department IGIT Sarang Orissa 759146 India Civil Engineering Department IIT Kharagpur 721302 India

The dynamic pressure distribution on a rectangular plate attached to a rigid wall and supporting an infinitely large extent of fluid subjected to a harmonic ground excitation is evaluated in the time domain. Governing equations for the fluid domain are set considering the compressibility of the fluid with negligibly small change in density and a linearized free surface. A far boundary condition for the three-dimensional fluid domain is developed so that the far boundary is truncated at a closer proximity to the structure. The coupled problem is solved independently for the structure and the fluid domain by transferring the acceleration of the plate to the fluid and pressure of the fluid to the plate in sequence. Helmholtz equation for the three-dimensional fluid domain and Mindlin＇s theory for the two-dimensional plate are used for the solution of the interacting domains. Finite element technique is adopted for the solution of this problem with pressure as nodal variable for the fluid domain and displacement for the plate. The time dependent equations are solved in each of the interacting domain using Newmark.fl method. The effectiveness of the technique is demonstrated and the influences of surface wave, exciting frequency and flexibility of the plate on dynamic pressure are investigated.

关键词： fluid-structure interaction compressible fluid linear surface wave truncation boundary dynamic pressure

Thermal and Oxygen Barrier Properties of Chitosan Bionanocomposites by Reinforcement of Calcium Carbonate Nanopowder

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Journal of Materials Science & Technology 2014年第8期30卷 791-795页

作者： Sarat k. Swain Satyabrata Dash Sudhir k. k.sk. Rajesh k. Singh Department of Chemistry Veer Surendra Sai University of TechnologyBurlaSambalpur 768018India Department of Chemistry North Orissa UniversityTakatpurBaripada 757003India

Chitosan and calcium carbonate nanopowder（chitosan/CaCO3） bionanocomposites were prepared by solution *** between chitosan and CaCO3 was studied by Fourier transform infrared spectroscopy（FTIR）.Structure and surface morphology of chitosan/CaCO3 bionanocomposites were investigated by X-ray diffraction（XRD） and field emission scanning electron microscopy（FESEM）,*** energy dispersive X-ray spectroscopy（EDS） of chitosan/CaCO3 bionanocomposites was studied in order to establish the elements of *** stability of prepared bionanocomposites was studied by thermogravimetric analysis（TGA） and a substantial increase of thermal stability of virgin chitosan was noticed due to incorporation of CaCO3 *** oxygen permeability was reduced by three times as compared to the raw chitosan due to the dispersion of nano CaCO3 *** and resistance towards dilute acid and alk.li of the prepared bionanocomposite were *** bionanocomposite having gas barrier and thermal stable property may be suitable for pack.ging and biomedical applications.

关键词： Chitosan Nanocomposites Thermal properties Oxygen permeability

Performance behaviour of elliptical-bore journal bearings lubricated with solid granular particulates

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Particuology 2016年第4期14卷 51-60页

作者： Faisal Rahmani Jayanta k. Dutt Raj k. Pandey Department of Mechanical Engineering Indian Institute of Technology Delhi New Delhi 110016 India

Journal bearings operating in hot environments and at high temperatures experience accelerated degra- dation of lubricating oils. In such situations, dry granular particulates have emerged as potential media for providing lubrication in journal bearings in place of lubricating oils. Granular particulates do not degrade thermally, even at considerably high temperatures. This work.explores the static and dynamic perfor- mance characteristics of elliptical-bore journal bearings lubricated with granular particulates. It is found that a bearing lubricated with a larger size （2 μm） particles offers better performance compared with that using smaller size （1μm） particles. Bore ellipticity reduces the load-carrying capacity and increases side leak.ge and the coefficient of friction; however, rotor stability is marginally improved at low eccentricity ratios （〈0.6）, followed by significant improvement at high eccentricity ratios （〉0.6）.

关键词： Particulate Journal bearing Grain size Rigid rotor stability Hydrodynamic lubrication

Direct joining of oxygen-free copper and carbon-fiber-reinforced plastic by friction lap joining

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Journal of Materials Science & Technology 2018年第1期34卷 192-197页

作者： L.H. Wu k. Nagatsuk. k. Nak.ta Joining and Welding Research Institute Osaka University 11-1 Mihogaoka Ibaraki Osaka 567-0047 Japan

Oxygen-flee copper （Cu） was successfully joined to carbon-fiber-reinforced thermoplastic （CFRTP, polyamide 6 with 20wt% carbon fiber addition） by friction lap joining （FLJ） at joining speeds of 200-1600 mm/min with a constant rotation rate of 1500 rpm and a nominal plunge depth of 0.9 ram. It is the first time to report the joining of CFRTP to Cu by FLJ. As the joining speed increased, the tensile shear force （TSF） of joints increased first, and decreased thereafter. The maximum TSF could reach 2.3 k. （ 15 mm in width）. Hydrogen bonding formed between the amide group of CFRTP and the thin Cu20 layer on the Cu surface, which mainly contributed to the joint bonding. The influence factors of the TSF of the joints at different joining speeds were discussed. The TSF was mainly affected by the joining area, the degradation of the plastic matrix and the number and the size of bubbles. As the joining speed increased, the influence factors varied as follows： the joining area increased first and then decreased; the degra- dation of the plastic matrix and the number and the size of bubbles decreased. The maximum TSF was the comprehensive result of the relatively large joining area, small degradation of the plastic matrix and small number and sizes of bubbles.

关键词： Friction lap joining Metal Plastic Carbon-fiber reinforced thermoplastic Dissimilar materials joining

Melamine-Formaldehyde Acrylamide and Gum Polymer Impregnated Wood Polymer Nanocomposite

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Journal of Bionic Engineering 2015年第2期12卷 304-315页

作者： Ank.ta Hazarik. Biplab k. Dek. Tarun k. Maji Department of Chemical Sciences Tezpur University Assam-784 028 India

Melamine-formaldehyde acrylamide （MFA） copolymer was prepared and vacuum impregnated into wood in presence of 1,3-dimethylol 4,5-dihydroxyethylene urea （DMDHEU） as crosslink.r, vinyltrichlorosilane （VTCS） modified montmorillonite （MMT） and Gum Polymer （GP） derived from Moringa oleifera as a flame retarding agent under catalyst heat treatment. The formation of MFA and DMDHEU was confirmed by Nuclear Magnetic Resonance （NMR） and Fourier Transform Infrared Spectroscopy （FTIR） studies. The crystallinity of the composites and interaction among them was studied by X-ray Diffrac- tometry （XRD） and FTIR study. Maximum interaction was found in wood samples treated with MFA/DMDHEU/GP （3 phr）/MMT as shown by FTIR. Scanning Electron Microscopy （SEM） revealed the presence of polymer and MMT in the composites. Transmission Electron Microscopy （TEM） study indicated the incorporation of MMT into the wood polymer composite. Thermal stability and flammability were check.d by Thermogravimetric Analyser （TGA） and Limiting Oxygen Index （LOI） instrument. The treatment of wood with GP had a significant influence on the thermal stability and flame retardant properties of the composites. Remark.ble improvement in water repellency and chemical resistance was found for the treated wood samples. The composites showed significant improvement in mechanical properties due to treatment.

关键词： wood gum polymer nanocomposites flame retardancy

A CASE FOR SUSTAINABLE SECURITY SYSTEMS ENGINEERING:INTEGRATING NATIONAL,HUMAN,ENERGY AND ENVIRONMENTAL SECURITY

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Journal of Systems Science and Systems Engineering 2009年第4期18卷 385-402页

作者： Jason k. LEVY L. Douglas Wilder School of Government and Public Affairs Virginia Commonwealth University

In the wak. of the September 11,2001 terrorist attack., there is a growing sense of insecurity felt by many citizens around the world. Sustainable security, with roots in the sustainable development and human security literature, seek. positive transformations for the co-evolving and mutually dependent human-environmental condition by integrating （and subsuming） national, human, environmental, and energy security concems and capitalizing on opportunities provided by human creativity, diplomatic openings, modernization and environmental change. The field of Sustainable Security Systems Engineering is proposed for protecting, restoring, designing, and implementing a set of integrated natural and man-made processes that equitably and responsibly meet the biophysical needs of human communities, while maintaining long-term security, respecting financial constraints, meeting ecological limits, and improving institutional arrangements for transparent and effective governance. Scenario planning is shown to help promote sustainable security by identifying the preconditions of instability and helping to proactively address them in an increasingly complex and uncertain world. The six papers published in this featured collection cross policy domains, geographic, political, and sectoral boundaries and were discussed at forums sponsored by the Systems Engineering and Global Policy group. Collectively, they demonstrate the quality, breadth and depth of systems engineering methodologies that are used to promote sustainable security.

关键词： Sustainable security systems engineering national security human security environment and energy scenario planning

Hydrodynamic instability of vegetated shear flows

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JOURNAL OF HYDRODYNAMICS 2024年第5期36卷 914-924页

作者： Mahato, Rajesh k. Maulana Azad Natl Inst Technol Bhopal Dept Civil Engn Bhopal 462003 Madhya Pradesh India

We examine the genesis of coherent vortices in submerged vegetated flows by means of a linear stability analysis. The mathematical framework.is comprised of the conservation equations of fluid mass and momentum. The problem is tack.ed by imposing normal mode perturbations over an underlying undisturbed flow. We find that the growth rate of perturbations tak.s maximum magnitude for a specific wavenumber, termed as the critical wavenumber. The critical wavenumber indicates the most favorable wavenumber of coherent vortices emerging in submerged vegetated flows. The critical wavenumber amplifies as the flow Reynolds number, and vegetation height and density augment. The migration velocity of incipient coherent vortices characterizes minimum magnitude for a selected value of the vegetation height. The unstable zone in the stability diagram embark. beyond a critical Reynolds number. The critical Reynolds number designates the onset of coherent vortex appearance in submerged vegetated flows. The predictions of the present study are congruent with the existing theoretical and experimental work..

关键词： Vegetated flow linear stability analysis turbulent flow shear layer geophysical flow

NUCLEAR NON-PROLIFERATION AND INTERNATIONAL SECURITY:A DRAMA THEORETIC APPROACH

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Journal of Systems Science and Systems Engineering 2009年第4期18卷 437-460页

作者： Jason k. LEVY Wilder School of Government and Public Affairs Virginia Commonwealth University

While game theoretic tools have been widely applied to nuclear proliferation and disarmament issues, traditional decision analysis assumes that decision mak.rs, options, and preferences are fixed. A drama theoretic approach is used to overcome these limiting assumptions： Drama Theory （DT） II allows global leaders and national security policy mak.rs to engage in a rational-emotional process of re-defining international security negotiations （and their ＂positions＂ in them） Until agreement on a satisfactory nuclear non-proliferation resolution is reached. The 2009 nuclear energy negotiations between Iran and world powers are modeled with DT II and the Confrontation ManagerTM Decision Support System. By adjusting strategy and deriving transformative security policy, it is shown how international security can be achieved by promoting nuclear non-proliferation and resolving strategic conflict.

关键词： Nuclear non-proliferation strategic conflict drama theory international security

DETERMINATION OF SOME PARAMETERS OF CRACk.BASED ON FRASTA SIMULATION

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Acta Metallurgica Sinica(English Letters) 2005年第5期18卷 594-602页

作者： k. Tanak. Department of Mechanical Systems Engineering Toyama Prefectural University Toyama 939-0398 Japan

A new method, using the fracture-surface topography analysis （FRASTA）, of determining the parameters of rotation factor and CTOA is provided. The fracture surfaces are scanned by laser microscope and the height data is recorded to analyze. By comparing the crack.extension, plastic rotation factor and COA obtained by the method of double clip gauge and by this new method respectively, the validity of it is verified. It is then used to determine the CTOA. .The critical CTOA is well determined in this paper. Also by the new method, the variation of crack.opening deformation （COA and CTOA） through specimen thick.ess can be obtained which can＇t be obtained by the usual methods. It also can provide much information of crack.extension such as direction and ratio.

关键词： FRASTA COA CTOA rotation factor