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Electrical properties of Na_(2)Pb_(2)r_(2)W_(2)Ti_(4)V_(4)O_(30)(r=Dy,Pr)ceramics

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Journal of Advanced Ceramics 2013年第2期2卷 112-118页

作者： Piyush r.das B.N.PArIDA r.PADHEE r.N.P.CHOUDHArY Department of Physics Institute of Technical Education&ResearchSiksha‘O’Anusandahan UniversityKhandagiriBhubaneswar 751030OdishaIndia

The polycrystalline samples of complex tungsten bronze(TB)Na_(2)Pb_(2)r_(2)W_(2)Ti_(4)V_(4)O_(30)(r=Dy,Pr)compounds were prepared by solid-state reaction ***-temperature preliminary structural studies confirm the formation of the compounds in the orthorhombic crystal *** studies of electrical properties of the materials using complex impedance spectroscopy technique exhibit that the impedance and related parameters are strongly dependent upon temperature and microstructure(bulk,grain boundary,etc).An observation of negative temperature coefficient of resistance(NTCr)suggests the materials have semiconducting *** variation of AC conductivity with temperature shows a typical Arrhenius behavior of the *** the samples obey Jonscher’s universal power *** existence of hopping mechanism in the electrical transport processes in the system with non-exponential type of conductivity relaxation is confirmed by electrical modulus analysis.

关键词： ceramics impedance spectroscopy electrical properties ferroelectricity microstructure

Closed-Form Solutions of Stress Intensity Factors for Semi-elliptical Surface Cracks in a Cylindrical Bar Under Pure Tension

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Acta Mechanica Solida Sinica 2022年第2期35卷 344-356页

作者： M.K.ramezani S.ramesh J.Purbolaksono r.das Centre of Advanced Manufacturing and Materials Processing Department of Mechanical EngineeringFaculty of EngineeringUniversity of MalayaKuala Lumpur 50603Malaysia Department of Mechanical Engineering University of PertaminaJakarta 12220Indonesia Sir Lawrence Wackett Aerospace research Centre School of EngineeringRMIT UniversityMelbourneVI 3000Australia

In this work,the stress intensity factors(SIFs)for a wide range of semi-elliptical surface cracks with different inclination angles in a cylindrical bar subjected to pure tension were investigated *** main parameters considered to evaluate the SIFs were the crack size ratio(a/d),the crack aspect ratio(a/c),and the crack inclination angle(0).The dual-boundary element met hod implemented in software BEASY was used to compute the SIF values for *** her more,the general closed-form solutions were proposed to evaluate the corresponding SIFs for Mode I,Mode II and Mode III types of fracture through curve fitting *** solutions can provide accurate and reliable values of stress intensity factors for a crack on a cylindrical bar under pure tension in a rapid way compared to those obtained using computational *** addition,these results can be used as inputs for failure studies and life evaluations of cracked cylinder under working conditions.

关键词： Stress intensity factor Surface crack Solid cylinder Closed-form solution Dual-boundary element method

Dielectric and electrical properties of Na_(2)Pb_(2)La_(2)W_(2)Ti_(4)Ta_(4)O_(30) electroceramics

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Journal of Advanced Ceramics 2012年第3期1卷 232-240页

作者： P.r.das S.BEHErA r.PADHEE P.NAYAK r.N.P.CHOUDHArY Department of Physics Institute of Technical Education&ResearchSiksha‘O’Anusandhan UniversityBhubaneswar-751030OdishaIndia Department of Physics Hi-tech College EngineeringBhubaneswar-75102OdishaIndia School of Physics Sambalpur UniversityJyoti ViharBurla-768019OdishaIndia

The polycrystalline sample of complex tungsten-bronze type compound(Na_(2)Pb_(2)La_(2)W_(2)Ti_(4)Ta_(4)O_(30))was prepared by a high-temperature solid-state reaction *** temperature preliminary structural study using X-ray diffraction(XrD)data exhibits the formation of a single-phase new *** SEM micrograph of the compound exhibits non uniform rectangular grains distributed throughout the sample *** studies of dielectric parameters(εr,tanδ)as a function of temperature and frequency,and P-E hysteresis(spontaneous polarization)confirmed the existence of ferroelectricity in the *** impedance spectroscopy analysis,carried out as a function of frequency at different temperatures,established a correlation between the microstructure and electrical properties of the *** electrical relaxation process occurring in the material is temperature *** activation energy found from the Arrhenius plot that the conduction process in the material is of mixed *** nature of frequency dependence of ac conductivity suggests that the material obeys Jonscher’s universal power law.

关键词： electronic material ferroelectricity XrD electrical conductivity

Distribution of mineral species in different coal seams of Talcher coalfield and its transformation behavior at varying temperatures

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International Journal of Coal Science & Technology 2016年第2期3卷 97-103页

作者： Amit Banerjee P. r. Mishra Ashok Mohanty K. Chakravarty r. das Biswas r. Sahu S. Chakravarty Analytical Chemistry Division CSIR - NationalMetallurgical Laboratory Jamshedpur Jharkhand 831007India Department of Metallurgical and Materials Engineering National Institute of Technology JamshedpurJharkhand 831014 India r&D Tata Steel Ltd Jamshedpur Jharkhand 831007 India

Mineral phase characterization and thorough understanding of its transformation behavior during combustion are imperative to know the potential utilization of coal in the thermal industries. The primary objective of this work is to analyze the quality of Indian Coals and obtain their mineral species-specific information at different depths. The samples were obtained from Talcher Coalfield, Odisha, India. Coal from four seam sections in the Talcher coalfield, India are mainly high ash coal （〉50 %） and volatile matter deceases along with the seam depth. XrD results show that the major mineral phases present in the coal are quartz and kaolinite. Siderite, illite, and anatase were found in minor quantities. It has been observed that the clay minerals （kaolinite, silimanite, illite） decompose at higher temperature and traces of dolomite, mullite, hematite etc. are formed during the process of combustion. Among the four seams （M2, M12, M24 and M43） studied, ash of M43 has high A1203%, TIO2% and K20% content and low SIO2%, CaO% and MgO% content. High acid- to-base ratios contributed to high ash fusion temperatures （IDT 〉 1500 ℃） and low slagging potential of the coals studied. relatively low fouling index （〈0.3） was estimated for all the coal seams studied. Furthermore, thermodynamic modeling software, FactSage, have been used to envision the mineral phase transformations that take place between 800 and 1500℃ during coal combustion.

关键词： Proximate analysis - Ultimate analysis FactSage XrD AFT Talcher coalfield

Device and circuit analysis of a sub 20 nm double gate MOSFET with gate stack using a look-up-table-based approach

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Journal of Semiconductors 2017年第12期38卷 37-41页

作者： S Chakraborty A dasgupta r das M Kar A Kundu C K Sarkar Department of Electronics and Communications Engineering Heritage Institute of Technology Kolkata 700107India Nano Device Simulation Laboratory Department of Electronics and Telecommunication EngineeringJadavpur UniversityKolkata 700032India

In this paper, we explore the possibility of mapping devices designed in TCAD environment to its modeled version developed in cadence virtuoso environment using a look-up table （LUT） approach. Circuit simu- lation of newly designed devices in TCAD environment is a very slow and tedious process involving complex scripting. Hence, the LUT based modeling approach has been proposed as a faster and easier alternative in ca- dence environment. The LUTs are prepared by extracting data from the device characteristics obtained from device simulation in TCAD. A comparative study is shown between the TCAD simulation and the LUT-based alternative to showcase the accuracy of modeled devices. Finally the look-up table approach is used to evaluate the perform- ance of circuits implemented using 14 nm nMOSFET.

关键词： 14 nm double gate MOSFET look-up table VerilogA

Synthesis of rNA-Amphiphiles via Atom Transfer radical Polymerization in the Organic Phase

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Precision Chemistry 2023年第5期1卷 326-331页

作者： Jaepil Jeong Grzegorz Szczepaniak Subha r.das Krzysztof Matyjaszewski Department of Chemistry Carnegie Mellon UniversityPittsburghPennsylvania 15213United States Center for Nucleic Acids Science&Technology Carnegie Mellon UniversityPittsburghPennsylvania 15213United States University of Warsaw Faculty of Chemistry02-093 WarsawPoland

The combination of hydrophobic polymers with nucleic acids is a fascinating way to engineer the self-assembly behavior of nucleic acids into diverse nanostructures such as micelles,vesicles,nanosheets,and *** we developed a robust route to synthesize a rNA macroinitiator with protecting groups on the 2′-hydroxyl groups in the solid phase using an oligonucleotide *** protecting groups successfully solubilized the rNA macroinitiator,enabling atom transfer radical polymerization(ATrP)of hydrophobic *** a result,the rNA−polymer hybrids obtained by ATrP exhibited enhanced chemical stability by suppressing *** addition,we demonstrated evidence of controlled polymerization behavior as well as control over the molecular weight of the hydrophobic polymers grown from *** envision that this methodology will expand the field of rNA−polymer conjugates while vastly enhancing the possibility to alter and engineer the properties of rNA-based polymeric materials.

关键词： ATrP rNA rNA-amphiphiles nucleic acid block copolymer rNA−polymer conjugate TBDMS SBiB phosphoramidite solid-phase rNA synthesis

Assessment of Sensitization in AISI 304 Stainless Steel by Nonlinear Ultrasonic Method

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Acta Metallurgica Sinica(English Letters) 2013年第5期26卷 545-552页

作者： Saju T.Abraham S.K.Albert C.r.das N.Parvathavarthini B.Venkatraman r.S.Mini K.Balasubramaniam Quality Assurance Division Indira Gandhi Centre for Atomic Research Department of Mechanical Engineering Government Engineering College Department of Mechanical Engineering Indian Institute of Technology

A nonlinear ultrasonic technique has been developed to evaluate sensitization in Type 304 stainless steel. In order to achieve diferent degree of sensitization（DOS）, specimens have been subjected to heat treatment at 675℃ at varying soaking time（0.5, 1.0, 2.0, 3.0 and 4.0 h）. Heat treated specimens were subjected to intergranular corrosion tests as per ASTM standards A262 and G108. Sensitization in longer soaked material has been confirmed through ditch microstructures, cracks on the bend tested specimens and higher degree of sensitization. Nonlinear ultrasonic studies showed variation in the nonlinearity parameter with soaking time which also confirms sensitization. A good correlation was observed between the degree of sensitization measured by the electrochemical potentiokinetic reactivation test and the ultrasonic nonlinearity *** study clearly demonstrated that nonlinear ultrasonic technique can be used as a potential technique for non-destructive characterization of sensitization in austenitic stainless steel.

关键词： Austenitic stainless steel Degree of sensitization Intergranular corrosion Nonlinear ultrasonics

Dielectric response and pyroelectric properties of lead-free ferroelectric Ba_(3)(VO_(4))_(2)

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Journal of Advanced Dielectrics 2015年第1期5卷 43-49页

作者： Biswajit Pati r.N.P.Choudhary Piyush r.das B.C.Sutar Department of Physics J.K.B.K.Government CollegeCuttack 753004India Department of Physics Institute of Technical Education and Research Siksha O Anusandhan UniversityBhubaneswar 751030India Department of Physics Veer Surendra Sai University of Technology BurlaSambalpur 768018India Department of Physics Hi-Tech College Engineering Bhubaneswar 751025India

The current paper presents results of dielectric response,pyroelectric behavior and conductivity study of lead-free ferroelectric barium orthovanadate(Ba_(3)(VO_(4))_(2)or Ba_(3)V_(2)O_(8))ceramic,for a wide range of temperature and *** X-ray diffraction study suggests the formation of a single-phase compound in trigonal crystal *** SEM micrograph of gold-coated pellet sample shows well-defined and homogeneous *** studies of dielectric parameters(ε_(r)and tanδ)of the compound as a function of temperature and frequency reveal their independence over a wide range of temperature and *** nature of Polarization versus electric field(P-E)hysteresis loop of Ba_(3)V_(2)O_(8)at room temperature suggests its ferroelectric *** temperature dependence of pyroelectric coefficient and figure of merits of the sample support its dielectric *** nature of variation of dc conductivity with temperature confirms the Arrhenius and negative temperature coefficient of resistance(NTCr)behavior of the material.

关键词： X-ray diffraction Palmierite structure dielectric properties pyroelectric properties

Ultralight,ductile metal mechanical metamaterials with super elastic admissible strain(0.1)

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Journal of Materials Science & Technology 2023年第31期162卷 227-233页

作者： H.Z.Zhong T.Song r.das C.W.Li J.F.Gu M.Qian Institute of Materials Modification and Modelling Shanghai Jiao Tong UniversityShanghai 200240China Centre for Additive Manufacturing School of EngineeringRMIT UniversityMelbourneVIC 3000Australia Sir Lawrence Wackett Aerospace research Centre School of EngineeringRMIT UniversityMelbourneVIC 3000Australia

Mechanical metamaterials are architectured cellular materials with unusual *** we report another type of metal mechanical metamaterials-their elastic admissible strain(EAS)is on the order of 0.1,compared to about 0.01 for common metallic *** conditions are required for a metal mechanical metamaterial to achieve this super EAS:(i)bending-dominated deformation;(ii)low density;(iii)an appropriate lattice topology,and(iv)an intrinsically high EAS for the lattice strut constituent *** findings of this work extend perspectives on metal mechanical metamaterials.

关键词： Metamaterials Lattice Superelasticity Elastic admissible strain Ti-6Al-4V Titanium