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Additive friction stir deposition of AZ31B magnesium alloy

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Journal of Magnesium and Alloys 2022年第9期10卷 2404-2420页

作者： Sameehan S.Joshi Shreyash M.Patil sangram mazumder Shashank Sharma Daniel A.Riley Shelden Dowden Rajarshi Banerjee Narendra B.Dahotre Department of Materials Science and Engineering University of North Texas3940 N Elm StDentonTX 76207USA Center for Agile and Adaptive Additive Manufacturing University of North Texas3940 N Elm StDentonTX 76207USA

The current work explored additive friction stir deposition of AZ31B magnesium alloy with the aid of MELD?***31B magnesium bar stock was fed through a hollow friction stir tool rotating at constant velocity of 400 rpm and translating at linear velocity varied from 4.2 to 6.3 mm/s.A single wall consisting of five layers with each layer of 140×40×1 mm^(3)dimensions was deposited under each processing ***,phase,and crystallographic texture evolutions as a function of additive friction stir deposition parameters were studied with the aid of scanning electron microscopy including electron back scatter diffraction and X-ray *** feed material and additively produced samples consisted of theα-Mg *** additively produced samples exhibited a refined grain structure compared to the feed *** feed material appeared to have a weak basal texture,while the additively produced samples experienced a strengthening of this basal *** additively produced samples showed a marginally higher hardness compared to the feed *** current work provided a pathway for solid state additive manufacturing of Mg suitable for structural applications such as automotive components and consumable biomedical implants.

关键词： Additive friction stir deposition Magnesium alloys Additive manufacturing Thermomechanical processing Materials processing Solid state additive manufacturing

Properties of filaments in solar cycle 20-23 from McIntosh Archive

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Research in Astronomy and Astrophysics 2019年第6期19卷 43-50页

作者： Rakesh mazumder Center of Excellence in Space Sciences India Indian Institute of Science Education and Research Kolkata

A filament is a cool, dense structure suspended in the solar corona. The eruption of a filament is often associated with a coronal mass ejection(CME), which has an adverse effect on space weather. Hence,research on filaments has attracted much attention in the recent past. The tilt angle of active region(AR)magnetic bipoles is a crucial parameter in the context of the solar dynamo, which governs the conversion efficiency of the toroidal magnetic field to poloidal magnetic field. Filaments always form over polarity inversion lines(PILs), so the study of tilt angles for these filaments can provide valuable information about generation of a magnetic field in the Sun. We investigate the tilt angles of filaments and other properties using McIntosh Archive data. We fit a straight line to each filament to estimate its tilt angle. We examine the variation of mean tilt angle with time. The latitude distribution of positive tilt angle filaments and negative tilt angle filaments reveals that there is a dominance of positive tilt angle filaments in the southern hemisphere and negative tilt angle filaments dominate in the northern hemisphere. We study the variation of the mean tilt angle for low and high latitudes separately. Investigations of temporal variation with filament number indicate that total filament number and low latitude filament number vary cyclically, in phase with the solar cycle. There are fewer filaments at high latitudes and they also show a cyclic pattern in temporal variation. We also study the north-south asymmetry of filaments with different latitude criteria.

关键词： Sun filaments,prominences-Sun magnetic fields-Sun corona-Sun activity-(Sun:)sunspots

Prospects of a β-SiC based IMPATT oscillator for application in THz communication and growth of aβ-SiC p-n junction on a Ge modified Si〈100〉substrate to realize THz IMPATTs

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Journal of Semiconductors 2010年第12期31卷 20-27页

作者： Moumita Mukherjee Nilratan mazumder Centre of Millimeter-Wave Semiconductor Devices and Systems Centre of Advanced Study in Radiophysics and ElectronicsUniversity of CalcuttaGirish Vidyaratna LaneKolkata 700009West BengalIndia IERCEM Institute of Information Technology West Bengal University of TechnologyKolkata 700017India

The prospects ofa p＋nn＋ cubic silicon carbide （3C-SiC/fl-SiC） based IMPATT diode as a potential solidstate terahertz source is studied for the first time through a modified generalized simulation scheme. The simulation predicts that the device is capable of generating an RF power output of 63.0 W at 0.33 THz with an efficiency of 13%. The effects of parasitic series resistance on the device performance and exploitable RF power level are further simulated. The studies clearly establish the potential of 3C-SiC as a base semiconductor material for a high-power THz IMPATT device. Based on the simulation results, an attempt has been made to fabricate β-SiC based IMPATT devices in the THz region. Single crystalline, epitaxial 3C-SiC films are deposited on silicon （Si）（100） substrates by rapid thermal chemical vapour deposition （RTPCVD） at a temperature as low as 800 ℃ using a single precursor methylsilane, which contains Si and C atoms in the same molecule. No initial surface carbonization step is required in this method. A p-n junction with an n-type doping concentration of 4 × 10^24 m-3 （which is similar to the simulated design data） has been grown successfully and the characterization of the grown 3C-SiC film is reported in this paper. It is found that the inclusion of Ge improves the crystal quality and reduces the surface roughness.

关键词： cubic (β)-SiC single drift IMPATT diode parasitic resistance terahertz oscillation RTPCVD growth p-n junction formation

Memristor-based RRAM with applications

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Science China(Information Sciences) 2012年第6期55卷 1446-1460页

作者： mazumder Pinaki Department of Electrical Engineering and Computer Science University of MichiganAnn ArborMI 48109USA

Recently acclaimed the fourth fundamental circuit element,the memristor was theoretically pre-dicted by Leon Chua in 1971,although its single device electronic implementation eluded the attention of inte-grated circuit designers for the past three decades and was first reported in 2008 by the Hewlett-Packard (HP) Laboratory researchers while developing crossbar-based ultra high-density nonvolatile ***-based hybrid nanoscale CMOS technology is expected not only to impact the flash memory industries pro-foundly,but also to revolutionize digital and neuromorphic *** memristor exhibits a dynamical resistance state that depends on its excitation history and which can be exploited to build transistor-less non-volatile semiconductor memory (NVSM),commonly known as resistive RAM (RRAM).This paper addresses an implementation scheme for memristor-based resistive random access memory (MRRAM),a nano-scale binary memory that is compatible with modern computer *** structure is similar to that of static random ac-cess memory (SRAM),but with the memristor replacing the underlying RS *** improving the MRRAM,we propose a multilevel memory with greater data density,which stores multiple bit information in gray-scale form in a memory *** computer simulations and numerical analyses verify the effectiveness of the proposed scheme in storing ASCII characters and gray-scale images in binary format.

关键词： memristor RRAM binary information memory multilevel memory

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GAITing the GUT

Cellular & Molecular Immunology 2018年第12期15卷 1082-1084页

作者： Barsanjit mazumder Center for Gene Regulation in Health and Disease Department of BiologyGeology and Environmental SciencesCleveland State UniversityClevelandOHUSA

The gastrointestinal tract contains one of the most abundant populations of macrophages in the body.1 These cells play a critical role in the maintenance of gut homeostasis and defend the integrity of epithelial crypts and the mucosal *** disruption of gut homeostasis can cause sustained inflammation mediated by intestinal *** inflammation plays a key role in ulcerative colitis(UC)and other forms of inflammatory bowel disease(IBD),2–4 an improved understanding of how inflammation is regulated in the gut is essential for the development of effective therapies for such diseases.

关键词： inflammation homeostasis sustained

Turbulence,suspension and downstream fining over a sand-gravel mixture bed

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International Journal of Sediment Research 2013年第2期28卷 194-209页

作者： K.GHOSHAL Rahul mazumder C.CHAKRABORTY B.S.mazumder Department of Mathematics Indian Institute of TechnologyKharagpur 721302India Assist.Prof. MIT CambridgeUSA Post-Doctoral Assoc. Fluvial Mechanics Laboratory Physics and Earth Science DivisionIndian Statistical InstituteKolkata 700108India Prof.

Flume experiments were carried out to study the turbulence and its impact on suspension and segregation of grainsizes under unidirectional flow conditions over the sand-gravel mixture *** components of fluid velocity with fluctuations were measured vertically using 3-D Micro-acoustic Doppler velocimeter(ADV).The theoretical models for velocity and sediment suspension have been developed based on the concept of mixing length that includes the damping effect of turbulence due to sediment suspension in the flow over the sand-gravel mixture *** analysis of segregation of grain-sizes along downstream of the bed has been performed using the principle of unsupervised learning or clustering *** data analysis suggests that there is a progressive downstream fining of sediment sizes with selective depositions of gravels,sand-gravels and sand materials along the stream,which may be segmented into three regions such as,the upstream,the transitional and the downstream *** contribution is relevant to understand the direction of ancient rivers,the bed material character in the river form,sorting process and its role in controlling the sediment flux through landscape.

关键词： Sand-gravel mixture Flow velocity ADV Suspension concentration Size-sorting Clustering

Fabrication and characterization of a GaN/(4H)SiC vertical pn power diode using direct and interfaced epitaxial-growth approaches

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Journal of Semiconductors 2013年第4期34卷 20-23页

作者： Bose Srikanta mazumder S K Laboratory for Energy and Switching-Electronics Systems Department of Electrical and Computer EngineeringUniversity of Illinois at ChicagoChicagoIL:60607USA

We report the fabrication and characterization of a vertical pn power diode which is realized using two separate epitaxial-growth mechanisms：（a） p-GaN over p-（4H）SiC, and （b） p-GaN over n-（4H）SiC with A1N as the interface layer. In all of the cases, n＋-doped （4H）SiC serves as the cathode substrate. Pd（200 A）/Au（10000 A） is used for the anode contact while Ni（1000A） is used for the bottom cathode contact. The measured forward drop of the pn diode with A1N as the interface material is found to be around 5.1 V; whereas, it is 3 V for the other sample structure. The measured reverse-blocking voltage is found to be greater than 200 V.

关键词： GaN (4H)SiC vertical pn power diode power electronics

Preparation,crystallization,microstructure and dielectric properties of lead bismuth titanate borosilicate glass ceramics

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Journal of Advanced Ceramics 2014年第3期3卷 194-206页

作者： Chandkiram RGAUTAM Abhishek MADHESHIYA Ranabrata mazumder Advanced Glass and Glass Ceramic Research Laboratory Department of PhysicsUniversity of LucknowLucknow 226007India Department of Ceramic Engineering National Institute of TechnologyRouerkela 769008India

Various bulk and transparent glasses were prepared by rapid melt quenching technique in the glass system 55[(Pb_(x)Bi_(1-x))TiO_(3)]-44[2Si_(O)2B_(2)O_(3)]-La2O3(x=0-0.7).The X-ray diffraction(XRD)studies of the glass samples confirmed the amorphous *** differential thermal analyses(DTA)were carried out from room temperature to 900℃with a heating rate of 10℃/*** DTA patterns of the samples showed one or more exothermic sharp peaks shifting towards lower temperature side with increasing concentration of bismuth oxide(BiO).On the basis of DTA results,the solid solution of bismuth titanum oxide(Bi_(2)Ti_(2)O_(7))/lead bismuth titanium oxide(Pb3Bi4Ti6O21)was precipitated in borosilicate glassy matrix as a major *** glasses were subjected to 4 h and 8 h heat treatment schedules to convert into glass *** analysis of these glass ceramic samples showed that the major crystalline phase of the entire glass ceramic samples with 0≤x≤0.5 is found to have cubic crystal structure,while it is tetragonal for glass ceramic sample with x=*** scanning electron microscopy(SEM)micrographs indicated the uniform distribution of Bi_(2)Ti_(2)O_(7)and Pb3Bi4Ti6O21 crystallites in the glassy matrix.

关键词： lead bismuth titanate differential thermal analysis(DTA) crystallization scanning electron microscopy(SEM) dielectric behavior

Thermal conductivity of dense hcp iron:Direct measurements using laser heated diamond anvil cell

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Geoscience Frontiers 2020年第5期11卷 1755-1761页

作者： Pinku Saha Aritra mazumder Goutam Dev Mukherjee National Centre for High Pressure Studies Department of Physical SciencesIndian Institute of Science Education and Research KolkataMohanpur CampusMohanpur741246NadiaWest BengalIndia

Thermal conductivity(k)of iron is measured up to about 134 *** measurements are carried out using the single sided laser heated diamond anvil cell,where the power absorbed by a Fe metal foil at hotspot is calculated using a novel thermodynamical *** conductivity of fee(γ)-Fe increases up to a pressure of about46 *** find thermal conductivity values in the range of 70-80 Wm-1K-1(with an uncertainty of 40%),almost constant with pressure,in the hcp(e)phase of *** attribute the pressure independent k above 46 GPa to the strong electronic correlation effects driven by the electronic topological transition(ETT).We predict a value of thermal conductivity ofε-Fe of about 40±16 Wm-1K-1 at the outer core of Earth.

关键词： Laser heated diamond anvil cell Thermal conductivity High pressure effects Geodynamo