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Diameter Dependent Ultrasonic Characterization of InAs Semiconductor Nanowires

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Open Journal of Acoustics 2015年第4期5卷 218-225页

作者： Mohit Gupta Punit K. Dhawan satyendra kumar verma Raja Ram Yadav Department of Physics University of Allahabad Allahabad India Government Polytechnic Gonda India

In this paper, we report the diameter dependent ultrasonic characterization of wurtzite structured InAs semiconductor nanowires at the room temperature. In this work, we have calculated the non-linear higher order elastic constants of InAs nanowires validating the interaction potential model. The ultrasonic attenuation and velocity in the nanowires are determined using the elastic constants for different diameters of the nanowires. Where possible, the results are compared with the experiments. Finally, we have established the correlation between the size dependent thermal conductivity and the ultrasonic attenuation of the nanowires.

关键词： Ultrasonic Attenuation Nanowires Elastic Constants Thermal Relaxation Time Thermal Conductivity

Liquefaction proneness of stratified sand-silt layers based on cyclic triaxial tests

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第7期15卷 1826-1845页

作者： Arpit Jain satyendra Mittal Sanjay kumar Shukla Department of Civil Engineering Indian Institute of TechnologyRoorkeeUttarakhandIndia School of Engineering Edith Cowan UniversityJoondalupPerthAustralia Department of Civil Engineering Indian Institute of Technology MadrasChennaiIndia Department of Civil Engineering BIT SindriIndia

Most studies on liquefaction have addressed homogeneous soil strata using sand or sand with fine content without considering soil *** this study,cyclic triaxial tests were conducted on the stratified sand specimens embedded with the silt layers to investigate the liquefaction failures and void-redistribution at confining stress of 100 kPa under stress-controlled *** loosening of underlying sand mass and hindrance to pore-water flow caused localized bulging at the sand-silt *** is observed that at a silt thickness of 0.2H(H is the height of the specimen),nearly 187 load cycles were required to attain liquefaction,which was the highest among all the silt thicknesses with a single silt ***,0.2H is assumed as the optimum silt thickness(t_(opt)).The silt was placed at the top,middle and bottom of the specimen to understand the effect of silt layer *** to the increase in depth of the silt layer from the top position(capped soil state)to the bottom,the cycles to reach liquefaction(N_(cyc,L))increased 2.18 ***,when the number of silt layers increased from single to triple,there was an increase of about 880%in N_(cyc,L).The micro-characterization analysis of the soil specimens indicated silty materials transported in upper sections of the specimen due to the dissipated pore *** main parameters,including thickness(t),location(z),cyclic stress ratio(CSR),number of silt layers(n)and modified relative density(D_(r,m)),performed significantly in governing the lique-faction *** this,a multilinear regression model is developed based on critical parameters for prediction of N_(cyc,L).Furthermore,the developed constitutive model has been validated using the data from the present study and earlier findings.

关键词： Cyclic triaxial tests Soil stratification Soil liquefaction Regression model

Experimental investigation for machinability aspects of graphene oxide/carbon fiber reinforced polymer nanocomposites and predictive modeling using hybrid approach

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Defence Technology（防务技术） 2021年第5期17卷 1671-1686页

作者： Jogendra kumar Rajesh kumar verma Department of Mechanical Engineering Madan Mohan Malaviya University of TechnologyGorakhpur273010India

This article explores the drilling behavior of polymer nanocomposites reinforced by Graphene oxide/Carbon fiber using a hybrid method of Grey theory and Principal component analysis(GR-PCA).An online digital dynamometer was employed for the evaluation of Thrust Force and *** image processing technique computes the *** surface methodology(RSM)considers the parameters,namely,drilling speed(S),feed rate(F),Graphene Oxide wt.%(G)in designing the experimentation *** component analysis(PCA)was used to tackle the response priority weight during the combination of multiple *** of variance(ANOVA)scrutinized the influence of parameters and intended the regression models to predict the ***-PCA evaluated the optimal parametric setting and remarked that feed rate acts as the most predominant *** higher feed rate and wt.%of G is responsible for surface damages like fiber pull-out,fiber fracture and cracks.A significant improvement in drilling responses has been obtained and also validates through confirmatory test and microstructure investigations.

关键词： Graphene oxide Polymer Carbon fiber RSM ANOVA GR-PCA

Surface Modification Aspects for Improving Biomedical Properties in Implants:A Review

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Acta Metallurgica Sinica(English Letters) 2024年第2期37卷 213-241页

作者： J.Sharath kumar Rakesh kumar Rajeev verma Industrial and Production Department Dr B R Ambedkar National Institute of Technology JalandharJalandharPunjab144008India

The primary focus during surgery is to ensure successful implantation by achieving long-term and stable fixation of *** surgery is now more focused on the development of novel biomaterials intended to improve implant *** obtain a better understanding of metal implants,this article investigated the causes of material failures in certain cases and analysed a few case *** interaction between the implant and bone tissue was a crucial aspect of successful implantation,and this study explored the factors influencing this interaction as well as ways to improve *** modern approaches used for modifying implant surfaces were systematically illustrated and briefly *** spray coatings were often favoured because of their wide range of coating materials,but other substantial surface modifications(such as friction stir processing and laser surface texturing)were also used for a selection of ***,implant surfaces with desirable features,such as biocompatibility,antibacterial properties,corrosion resistance,and wear resistance,were essential for optimising implant *** systematic review's main aim is to provide exhaustive reference information and a broad overview to advance the production and design of orthopaedic implants.

关键词： Biomaterials Surface treatments Thermal spray coatings Antibacterial Biocompatibility Corrosion resistance Wear resistance

Battery energy storage-based system damping controller for alleviating sub-synchronous oscillations in a DFIG-based wind power plant

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Protection and Control of Modern Power Systems 2023年第2期8卷 260-277页

作者： Neevatika verma Narendra kumar Rajeev kumar Department of Electrical Engineering Delhi Technological UniversityNew DelhiIndia Electrical Engineering Department Jamia Millia IslamiaNew DelhiIndia Electrical and Electronics Engineering Department KIET Group of InstitutionsGhaziabadIndia

This paper presents the issue of the Sub-synchronous resonance(SSR)phenomenon in a series compensated DFIG-based wind power plant and its alleviation using a Battery Energy Storage-based Damping Controller(BESSDCL).A supplementary damping signal is developed considering the angular speed deviation and is incorporated into the BESS control ***-area Measurement System data is used to determine the angular speed deviation.A lin-earized system model is developed to perform eigenvalue analysis,and to detect and examine unstable SSR *** variation of wind speed and three-phase fault are also taken into consideration to validate the robustness of the *** further verify the efficacy of the proposed damping controller,time-domain simulations are performed using MATLAB/*** application of the proposed BESSDCL stabilizes all the unstable system modes effectively at wind speeds of 7 m/s,9 m/s,and 11 m/s,and at 40%,50%,and 60%series compensation levels,as well three-phase fault conditions.

关键词： Battery energy storage system Damping controller Doubly-fed induction generator(DFIG) Series

Modeling the effect of time delay in implementation of mitigation policies on the control of atmospheric greenhouse gases

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International Journal of Biomathematics 2023年第8期16卷 75-108页

作者： Alok kumar verma Maitri verma Department of Mathematics School of Physical and Decision Science Babasaheb Bhimrao Ambedkar University Lucknow India

Mitigation of the enhanced greenhouse gas(GHG)concentrations in the Earth's atmosphere is imperative to meet the climate change mitigation *** of many countries are developing and implementing various mitigation strategies to reduce their GHG ***,a time delay between the formulation and implementation of these mitigation policies can affect their effectiveness in controlling greenhouse gas levels in the *** work presents a nonlinear mathematical model to investigate the effect of application of mitigation strategies and the delay involved in their implementation over the reduction of atmospheric greenhouse *** model formulation,it is assumed that the mitigation strategies work two-fold;first they reduce the GHG emission rate from the anthropogenic source and second they increase the removal rate of greenhouse gas from the atmosphere.A comprehensive stability analysis of the proposed model system is made to examine its long-term *** model analysis shows that an increase in the implementation rate of mitigation strategies and their efficiencies to cut down the GHG emission rate from point sources and increase the GHG uptake rate lead to reduction in equilibrium GHG *** is found that a long delay in the execution of mitigation policies can destabilize the system dynamics and leads to the generation of periodic *** expression for the threshold value of the delay parameter at which periodic oscillations arise via Hopf-bifurcation is *** stability and direction of bifurcating periodic solutions are discussed.A sensitivity analysis is performed to investigate the effect of changes in key parameters over system dynamics.

关键词： Mathematical model greenhouse gases global warming mitigation strategies time delay Hopf-bifurcation

Influence of rooftop telecommunication tower on set back-step back building resting on different ground slopes

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Earthquake Engineering and Engineering Vibration 2019年第2期18卷 351-362页

作者： Amit Thakur Deepankar kumar Ashish Surender kumar verma Civil Engineering Department Kurukshetra University Civil Engineering Department Maharaja Agrasen Institute of Technology Maharaja Agrasen University Civil Engineering Department Punjab Engineering College (Deemed to be University)

In the hilly region due to scarcity of the plain area, buildings like set back-step back are more often used and also as a big surge in the telecommunication industries, rooftop tower adaptation is very common story nowadays. In the present study an analogy has been drawn to find out the influence of the rooftop telecommunication tower on the setback-step back building resting on ground at 20° and 30° slopes. A dynamic analysis has been performed and compared on the 4 legged angled section telecommunication tower which is located on the roof top of set back-step back building by varying positions of tower with the existing host structure built up on ground slope of 20° and 30° in both directions(X and Y).

关键词： rooftop telecommunication tower set back-step back building response spectrum analysis steel, RC frame, earthquake SAP2000

Polyaxial strength criterion and closed-form solution for squeezing rock conditions

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第3期12卷 507-515页

作者： Rupesh kumar verma Sarvesh Chandra Department of Civil Engineering Indian Institute of Technology KanpurKanpur208016India

In this paper,a nonlinear strength criterion is proposed using the average of intermediate(σ2)and minor(σ3)principal stresses in place of σ3 in Ramamurthy(1994)’s strength *** proposed criterion has the main advantages of negligible variation of strength parameters with confining stress and ability to link with conventional strength ***,a new closed-form solution based on the proposed criterion is derived and validated for Chhibro Khodri ***,analytical solutions including Singh’s elastoplastic theory,Scussel’s approach,and closed-form solutions based on conventional and modified Ramamurthy(2007)criteria are compared with the results of proposed *** is shown that the in situ squeezing pressure predictions made by the proposed approach are more ***,a parametric study of the present analytical solution is carried out,which displays explicit dependency of tunnel stability on internal support pressure and tunnel *** influence of tunnel geometry is observed to be dependent on the applied support pressure.

关键词： Intermediate principal stress Squeezing pressure Closed-form solution Polyaxial strength criterion

Synthesis and characterization of rare earth metal doped tungsten trioxide photocatalyst for degradation of Rhodamine B dye

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Journal of Rare Earths 2023年第9期41卷 1302-1310,I0002页

作者： Pooja Nehra Amita Khatri Anil kumar satyendra Singh Pawan S.Rana Department of Physics Deenbandhu Chhotu Ram University of Science and TechnologyMurthal1339SonipatHaryanaIndia Special Centre for Nanoscience Jawaharlal Nehru University New Delhi10067India

Nowadays,it is concern for researchers that due to high recombination rate of photogenerated charge carriers in tungsten trioxide(WO_(3)) nanoparticles,the future applications are limited in the field of *** we attempt to synthesize tungsten trioxide nanoparticles with different doping concentrations of lanthanum i.e.2 wt%,4 wt%,6 wt% and 8 wt%.The synthesized samples were characterized by using various characterization techniques:X-ray diffraction(XRD),Raman spectroscopy,Fourier transform infrared spectroscopy(FTIR),photoluminescence spectra(PL),transmission electron microscopy(TEM),energy dispersive X-ray(EDX) and UV-Vis ***_(3) retains its monoclinic structure even after doping which was confirmed by XRD *** helps to descry functional groups present in the *** size of nanoparticles was calculated by using *** confirms the absence of any impurity in the synthesized *** spectroscopy confirms the presence of a large number of imperfections induced in the lattice of WO_(3).The rate of recombination was analyzed by photoluminescence(PL) spectroscopy and is minimum in 4 wt% doping of *** optical bandgap was calculated using UV-Vis spectroscopy and becomes narrow along with the doping ***,it is found that doping of La in WO_(3) has considerably ameliorate the photocatalytic activity by reducing rate of recombination due to the trapping of electrons by defects introduced in the *** decolorization of Rhodamine B(RhB) dye was performed and the values of c/c_0 and rate constant(k) confirm that the 4 wt% doping shows maximum degradation *** kinetic study for photodegradation of Rhodamine B was done by using various kinetic models and results show that the reaction follows first order kinetics very ***,optimum doping of lanthanum increases the decolorization ability of WO_(3) towards RhB dye.

关键词： Photocatalytic activity WO_(3)nanoparticles Rhodamine B dye Rare earth doping Visible light