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Drilling study on lightweight structural Mg/SiC composite for defence applications

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Defence Technology（防务技术） 2019年第4期15卷 557-564页

作者： k. Balamurugan M. uthayak.mar S. Thirumalai k.maran G.S. Samy u.T.S. Pillai Department of Mechanical Engineering VFSTR (Deemed to be University) Guntur 522213 India Faculty of Mechanical Engineering Kalasalingam University Krishnankoil 626126 Tamil Nadu India CSIR-NIIST Material Science and Technology Division Thiruvananthapuram 695019 India

Heat energy generated during machining has been found to have a greater influence on determining the machinability of the *** this work.magnesium-based silicon carbide composite,which has been identified as a suitable lightweight application material,is prepared with the weight ratio of 90:10 by a stir casting *** available HSS drill tools with different diameters of 4,6 and 8 mm are used to perform the drilling operations with governing parameters of spindle speed,feed rate and constant depth of *** image camera of the FLIR E60 series is used to measure the temperature variation in the cutting zone at different operating *** influences of machining temperature on chip morphology,tool wear and surface profile of the machined samples are *** speed has been found to have a significant effect on machining *** spindle speed increases,the diameter of drill tool increases the tool wear and surface profile,*** abrasion and adhesive type of wears are observed in the drill ***,change from abrasion to adhesive wear is noticed with the increase of the diameter of the drill *** plots are drawn with respect to the interaction of governing parameters along with the work.ng temperatures obtained under different machining conditions.

关键词： Magnesium SiC Drilling Thermal effect Chip morphology Tool wear

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

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维普期刊数据库

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Dank.an Bre men

德语人文研究 2000年第4期 62-66页

作者： RuDOLF ALEXANder schrder

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

Multiple magnetic transitions and magnetocaloric effect of Tb_(4)Coln alloy

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Journal of Rare Earths 2023年第11期41卷 1721-1727,I0003页

作者： Remya u.D. Arun k. Swathi S. Athul S.R. Andrea Dzubinsk. Marian Reiffers Nagalak.hmi R. Intermetallics and Non-linear Optics Laboratory Department of PhysicsNational Institute of TechnologyTiruchirappalli620015India CPM-TIP University Pavol Jozef Safarik04011KošiceSlovakia Faculty of Humanities and Natural Sciences Presov UniversityPresovSlovakia Institute of Experimental Physics SASKosiceSlovakia

We report on the magnetic,magnetocaloric,thermal,and electrical transport properties of Tb_(4)Coln alloy,which crystallizes in two phases,Tb_6Co_(2.1)In_(0.8)(space group Immm)and Tb_(2)In_(0.9)Co_(0.1)(space group P6_(3)/mmc),*** alloy reveals three successive magnetic transitions around T_(1)(163 k.,T_(2)(50 k.,and T_(3)(29 k.,respectively,associated with paramagnetic to ferromagnetic transition and two sequential antiferromagnetic *** low-temperature transition T_(3) follows the first-order magnetic behavior and exhibits the field-induced magnetic ***,T_(2) and T_(1) are found to be second-order in nature which opens a possibility for hysteresis-free magnetocaloric *** magnetocaloric properties are determined using different magnetocaloric figures of merits such as-ΔS_(M),ΔT_(ad).RCP,and TEC(10).Additionally,the universal curve behavior in the isothermal entropy change unveils the variation in critical exponents around T_(1) and T_(2) due to the magnetic inhomogeneity in the ***,the electrical transport properties of the metallic alloy denote the maximum magnetoresistance of-10%around T_(1).

关键词： Multiple magnetic transitions Order of magnetic transition Magnetocaloric effect Magnetoresistance universal curve behavior Rare earths

Synthesis of Nano-sized Barium Titanate Powder by Solid-state Reaction between Barium Carbonate and Titania

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Journal of Materials Science & Technology 2007年第5期23卷 655-658页

作者： u.Manzoor D.k.k.m Department of Physics COMSATS Institute of Information TechnologyIslamabadPakistan Department of Materials Science and Engineering Korea Advanced Institute of Science and Technology(KAIST)DaejeonKorea

Size control of BaTiO3 in solid-state reaction between BaCO3 and TiO2 was demonstrated by varying the size of TiO2 and milling conditions of BaCO3. The smaller TiO2 particles had higher surface area, resulting in faster initial reaction. The mechanically milled BaCO3 particles accelerated the diffusion process and decreased the calcinations temperature. It can be deduced from the results that the size control is possible and nano-sized BaTiO3 particles with about 60 nm can be synthesized by using the conventional solid-state reaction between BaCO3 and TiO2.

关键词： Barium tltanate Mechanical milling Solid-state reaction Nano particles

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

DEVELOPMENT OF FRASTA SIMuLATION SOFTWARE

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Acta Metallurgica Sinica(English Letters) 2006年第3期19卷 165-170页

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

Fracture-surface topography analysis （FRASTA） was successfully used to simulate the process of crack.and calculate parameters of crack.such as the crack.opening angle （COA） and crack.tip opening angle （CTOA）. But because the amount of calculation is large, errors are often made during the course of calculation. FRASTA simulation software, namely fracture surface analyst （FSA ） is developed and a series of center-crack.d tension （CCT） and double edge notched （DEN） specimens of different materials with different sizes are tested, their fracture surfaces are scanned by non-contact 319 scanning system and the elevation data of the fracture surfaces is recorded. FSA used the recorded elevation data of fracture surfaces to simulate the process of crack.based on the principle of FRASTA. Results show that FSA can accurately simulate the process and calculate the parameters of crack.

关键词： FRASTA (fracture-surface topography analysis) COA (crack.opening angle) CTOA (crack.tip opening angle) CCT (center-crack.d tension) DEN (double edge notched)

SuRFACE EXCITATION PARAMETER IN QuANTITATIVE SuRFACE ANALYSIS BY ELECTRON SPECTROSCOPY

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 313-318页

作者： k. Salma Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics University of Science and Technology of China

The investigation of influence of surface effects on the energy spectra of elect rons is essential for comprehensive understanding of electron-solid interactions as well as quantitative analysis. The accuracy of the analysis depends on the m odels for elastic and inelastic interactions. Electrons impinging on a solid or escaping from it suffer losses in the surface layer. The energy loss spectra the refore have contributions from surface excitations. The role of surface excitati ons is characterized by surface excitation parameter (SEP), which indicates the number of surface plasmons created by an electron crossing the surface. The imag inary part of complex self-energy of an electron is related to the energy loss c ross section. SEP is numerically computed using self-energy formalism and compar ed with the results as described and calculated by different work.rs.

关键词： surface plasmons surface excitations parameter self-energy