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Determining the relationship between chemical composition and size, shape and effective density of airborne fine particles through concurrent use of inertial and optical based measurements

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Particuology 2016年第5期14卷 93-101页

作者： anand Kumar Tarun Gupta Environmental Engineering and Management Program Indian Institute of Technology Kanpur Kanpur 208016 India Institute of Atmospheric and Climate Science Swiss Federal Institute of Technology Zurich Zurich 8092 Switzerland Department of Civil Engineering Indian Institute of Technology Kanpur Kanpur 208016 India

This study presents the development of a medium flow, multiple slit based PM2.5 （particle aerodynamic diameter 〈2.5 μm） inertial impactor. Its performance was compared with that of a light scattering based optical particle sizer in a field study and in controlled lab based experiments using polydisperse dolomite powder as test aerosol. The impactor＇s optimum nozzle configuration had a cutoff size of 2.51 μm （aero- dynamic diameter） at an operating flow rate of 215 L/rain with a pressure drop of 0.35 kPa across the impactor stage. Because the apparent particle density of an ambient aerosol depends on the physical properties and the chemical composition of the particles, the PM2.5 mass concentration was measured with an optical particle sizer and an inertial impactor over a weekday and a weekend day in a field study during which the effective particle shape factor and density were in tandem modified in order to com- pare the results from the two sampling techniques. The correlation of the two instrument results tended towards 1：1 with increasing values of shape factor （irregular shaped） and effective particle density. This observation was supported through chemical investigations of the collected mass, which showed a higher percentage contribution from elements which are mostly of crustal nature （namely, Ca, Fe, and Mg）.

关键词： lmpactor PM2.5 Optical particle counter Effective particle density Shape factor

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Effective field theory approach to lepto-philic self-conjugate dark matter

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Chinese Physics C 2021年第2期45卷 257-269页

作者： Hrishabh Bharadwaj ashok Goyal Department of Physics&Astrophysics University of DelhiDelhiIndia

We study self-conjugate dark matter(DM)particles interacting primarily with Standard Model(SM)leptons in an effective field theoretical *** consider SM gauge-invariant effective contact interactions between Majorana fermion,real scalar and real vector DM with leptons by evaluating the Wilson coefficients appropriate for interaction terms up to dimension 8,and obtain constraints on the parameters of the theory from the observed relic density,indirect detection observations and from the DM-electron scattering cross-sections in direct detection *** energy LEP data has been used to study sensitivity in the pair production of low mass(≤80 GeV)DM *** production of DM particles of mass≥50 GeV in association with mono-photons at the proposed ILC has rich potential to probe such effective operators.

关键词： dark matter theory mono-photon indirect and direct detection effective operator

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Julia sets of permutable Holomorphic maps Dedicated to Professor Sheng GONG on the occasion of his 75th birthday

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Science China Mathematics 2006年第11期49卷 1715-1721页

作者： SINGH anand P Department of Mathematics University of Jammu Jammu-180006India

Let f and g be two permutable transcendental holomorphic maps in the *** shall discuss the dynamical properties of f, g and f o g and prove, among other things, that if either f has no wandering domains or f is of bou... 详细信息

关键词： Julia set, Fatou set, permutable maps.

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Effect of processing parameters on the electromagnetic radiation emission during plastic deformation and crack propagation in copper-zinc alloys

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第11期7卷 1800-1809页

作者： KUMAR Rajeev MISRA ashok Department of Mechanical Engineering Birla Institute of Technology Mesra 835215 Ranchi India

This paper presents some investigations on the effect of processing parameters on the emission of electromagnetic radiation （EMR） during plastic deformation and crack propagation in copper-zinc alloys. Timing of the EMR emissions, maximum stress during crack instability, stress-intensity factor, elastic strain energy release rate, maximum EMR amplitude, RMS value of EMR amplitude, EMR frequency and electromagnetic energy release rate were analysed for the effect of rolling directions at different percentage of zinc content in Cu-Zn alloy specimens. The same parameters were also analysed for 68-32 Cu-Zn alloy specimens at different annealing temperatures and at different angles 0, to the rolling direction. EMR emissions are observed to be highly anisotropic in nature. At θ=45° to 60°, marked changes in mechanical and electromagnetic parameters were observed. Specimens annealed at 500℃, just above the recrystallization temperature, and at 700℃, when grain-size growth is rapid, EMR responses have been found to have well-defined patterns.

关键词： Radiation Plastic deformation Rolling direction Annealing Fracture

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In-line digital holography for dynamic metrology of MEMS(Invited Paper)

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Chinese Optics Letters 2009年第12期7卷 1117-1122页

作者： Vijay Raj Singh anand Asundi School of Mechanical and Aerospace Engineering Nanyang Technological University

In-line digital holography helps to relax the spatial resolution requirement on charge-coupled device sensors for digital recording of holograms and to utilize the full sensing area for image reconstruction which provides larger field of view and better imaging resolution. In this letter, a lensless in-line digital holographic microscopy is presented for dynamic metrology of micro-electro-mechanical system devices. The methodologies of interferometry and time-averaged in-line digital holography are presented for dynamic measurements, which are also useful for simultaneous suppression of in-line waves from real image wave. The experimental results are presented for dynamic thermal characterization of microheater and vibration analysis of cantilevers.

关键词： line MEMS

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Properties of cement grout modified with ultra-fine slag

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Frontiers of Structural and Civil Engineering 2018年第1期12卷 58-66页

作者： Sowmini GOPINATHAN K B anand Department of CiviI Engineering Amrita School of Engineering Coimbatore Amrita ~Tshwa Vidyapeetham Amrita University Pincode 641 112 India

The purpose of the study is to obtain a cement grout with improved performance. The grout mixes of the present study contain cement, ultra-fine slag （UFS）, super plasticizer and water. Properties like flowability, bleeding, compressive strength and shrinkage of cement grouts have been studied. Rheological parameters were also studied in order to explain the grout workability. The results show that, cement replacement with slag in grouts could reduce bleeding substantially without affecting the workability of the mixes. Introduction of slag enhanced the compressive strength and reduced shrinkage reasonably. Ultra-fine slag can be used as a supplementary cementitious material in cementitious grouts in order to improve the grout behavior.

关键词： cement grout ultra-fine slag flowability bleeding viscosity

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Efficient ID-based proxy multi-signature scheme secure in random oracle

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Frontiers of Computer Science 2012年第4期6卷 421-428页

作者： Rajeev anand SAHU Sahadeo PADHYE Department of Mathematics Motilal Nehru National Institute of TechnologyAllahabad-211004India

Proxy signature schemes enable an entity to del- egate its signing rights to any other party, called proxy signer. As a variant of proxy signature primitive, proxy multi- signature allows a group of original signers to delegate their signing capabilities to a single proxy signer in such a way that the proxy signer can sign a message on behalf of the group of original signers. We propose a concrete ID-based proxy multi-signature scheme from bilinear pairings. The proposed scheme is existential unforgeable against adaptively chosen message and given ID-attack in random oracle model under the computational Diltie-Hellman （CDH） assumption. The fascinating property of new scheme is that the size of a proxy multi-signature is independent of the number of original sign- ers. Furthermore the proposed scheme is simple and com- putationally more efficient than other ID-based proxy multi- signature schemes.

关键词： ID-based signature scheme bilinear pairings,proxy multi-signature computational Diffie-Hellman prob-lem (CDHP) random oracle

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Influence of rare-earth ions on structural and magnetic properties of CdFe_2O_4 ferrites

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Rare Metals 2010年第2期29卷 168-173页

作者： ashok Gadkari Tukaram Shinde Pramod Vasambekar Department of Physics GKG CollegeKolhapur 416012 India Department of Physics KRP Kanya Mahavidylaya Islampur 415409 India Department of Electronics Shivaji University Kolhapur 416004 India

Nano-sized powders of rare-earth ions added CdFe2O4 ferrites were synthesized by oxalate co-precipitation *** influence of R ions（R = Sm3＋, Y3＋, and La3＋） on the microstructure and magnetic properties of CdFe2O4 ferrites was ***, SEM, FTIR, and magnetic hysteresis loops were used for analyzing the *** addition of R ions alters the structure of the powders and decreases the crystalline size, lattice constant, and grain *** magnetic properties such as saturation magnetization, remanent magnetization, and magnetic moment increased due to addition of rare-earth ions in CdFe2O4 *** formation of secondary phase on the grain boundaries supports the abnormal *** spectra show two absorption *** suggest that the magnetic properties depend on the particular method of preparation and additives.

关键词： nanoparticle rare-earth ions magnetization grain size hysteresis

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Investigation on the Reduction of Center of Mass Oscillations of Flexible Flapping Fins

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Journal of Bionic Engineering 2016年第4期13卷 544-557页

作者： ashok K Kancharala Michael K Philen Aerospace and Ocean Engineering Virginia Polytechnic Institute and State University Blacksburg VA 24061 USA

Nature has been a source of inspiration for developing advanced autonomous aerial and underwater vehicles. The bodies with flapping appendages produce Center of Mass （COM） oscillations as the flapping fins generate forces oscillatory in nature. The vehicles with larger COM oscillations pose the problems of control and maneuverability and this paper discusses the effect of flexibility and other operating parameters such as heaving, pitching amplitudes and operating frequency on COM oscillations. A detailed theoretical investigation has been carried out to predict the optimal operating parameters along with the fin stiffness to reduce the COM oscillations for a given Self-Propelled Speed （SPS）. Experiments have been performed to validate the theoretical results. It has been observed that the flexible fins operating at larger frequencies produce lower COM oscillations compared to stiffer fins operating at lower frequencies for a given mean thrust/SPS, and that the trailing edge amplitude along with the deformation pattern play a role in the generation of COM oscillations.

关键词： flapping fin fluid-structure interaction optimization digital image correlation

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Morphology of single inhalable particle inside public transit biodiesel fueled bus

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Journal of Environmental Sciences 2010年第2期22卷 263-270页

作者： Kaushik K.Shandilya ashok Kumar Department of Civil Engineering The University of Toledo

In an urban-transit bus, fueled by biodiesel in Toledo, Ohio, single inhalable particle samples in October 2008 were collected and detected by scanning electron microscopy and energy dispersive X-ray spectrometry （SEM/EDS）. Particle size analysis found bimodal distribution at 0.2 and 0.5 μm. The particle morphology was characterized by 14 different shape clusters： square, pentagon, hexagon, heptagon, octagon, nonagon, decagon, agglomerate, sphere, triangle, oblong, strip, line or stick, and unknown, by quantitative order. The square particles were common in the samples. Round and triangle particles are more, and pentagon, hexagon, heptagon, octagon, nonagon, decagon, strip, line or sticks are less. Agglomerate particles were found in abundance. The surface of most particles was coarse with a fractal edge that can provide a suitable chemical reaction bed in the polluted atmospheric environment. The three sorts of surface patterns of squares were smooth, semi-smooth, and coarse. The three sorts of square surface patterns represented the morphological characteristics of single inhalable particles in the air inside the bus in Toledo. The size and shape distribution results were compared to those obtained for a bus using ultra low sulfur diesel.

关键词： individual particle environmental scanning electron microscope urban-public transit bus ultra low sulfur diesel

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