检索结果-南通市图书馆

Frontiers of Mechanical Engineering 2016年第4期11卷 374-387页

作者： Jagdeep SINGH rajiv kumar sharma Department of Mechanical Engineering National Institute of Technol-ogy Hamirpur Himachal Pradesh-177005 India

Electrical discharge machining (EDM) is a well-known nontraditional manufacturing process to machine the difficult-to-machine (DTM) materials which have unique hardness properties. Researchers have successfully performed hybridization to improve this process by incorporating powders into the EDM process known as powder-mixed EDM process. This process drastically improves process efficiency by increasing material removal rate, micro-hardness, as well as reducing the tool wear rate and surface roughness. EDM also has some input parameters, including pulse-on time, dielectric levels and its type, current setting, flushing pressure, and so on, which have a significant effect on EDM performance. However, despite their positive influence, investigating the effects of these parameters on environmental conditions is necessary. Most studies demonstrate the use of kerosene oil as dielectric fluid. Nevertheless, in this work, the authors highlight the findings with respect to three different dielectric fluids, including kerosene oil, EDM oil, and distilled water using one-variable-at-a-time approach for machining as well as environmental aspects. The hazard and operability analysis is employed to identify the inherent safety factors associated with powder-mixed EDM of WC-Co.

关键词： WC hazard and operability analysis (HAZOP) discharging aerosol concentration dielectrics powders

Proactive Connection Recovery Strategy with Recovery Time Constraint for Survivable Elastic Optical Networks

在线全文

学校读者我要写书评

暂无评论

China Communications 2021年第9期18卷 236-248页

作者： Dinesh kumar rajiv kumar Neeru sharma Department of Electronics&Communication Engineering Jaypee University of Information Technology WaknaghatSolan(HP)India

This paper presents a halfway signaling exchange shared path protection(HSE-SPP)on the backup route for a fast connection recovery *** the proposed HSE-SPP,a pre-assigned intermediate node on the backup route is chosen for signaling *** connection fails,source and destination nodes simultaneously generate backup connection setup messages to the pre-assigned intermediate node on the reserved backup *** the intermediate node,signaling process occurs,and acknowledgment is generated for data transmission to the respective end ***,connection recovery time by applying HSE-SPP becomes very *** are performed for network parameters and results are verified with existing *** average recovery time(RT),bandwidth blocking probability(BBP),bandwidth provisioning ratio(BPR),and resource overbuild(RO)ratio of HSE-SPP for ARPANET is 13.54 ms,0.18,3.02,0.55,and for dedicated path protection(DPP)are 13.20 ms,0.56,6.30,3.75 and for shared path protection(SPP)22.19 ms,0.22,3.23,0.70 ***,average RT,BBP,BPR and RO of HSE-SPP for COST239 are8.33 ms,0.04,1.64,0.26,and for DPP 4.23,0.47,3.50,2.04,and for SPP 11.81,0.08,1.66,0.27 ***,results of the proposed strategy are better in terms of RT,BBP,BPR,and RO ratio.

关键词： routing and spectrum assignment halfway signaling exchange-shared path protection(HSE-SPP) dedicated path protection bandwidth blocking probability(BBP)

Impact of open dumping of municipal solid waste on soil properties in mountainous region

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2018年第4期10卷 725-739页

作者： Anchal sharma Ashok kumar Gupta rajiv Ganguly Department of Civil Engineering Jaypee University of Information Technology

This paper presents the effect of open dumping of municipal solid waste(MSW) on soil characteristics in the mountainous region of Himachal Pradesh, India. The solid waste of dumpsite contains various complex characteristics with organic fractions of the highest proportions. As leachate percolates into the soil, it migrates contaminants into the soil and affects soil stability and strength. The study includes the geotechnical investigation of dump soil characteristics and its comparison with the natural soil samples taken from outside the proximity of dumpsites. The geochemical analysis of dumpsite soil samples was also carried out by scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS).Visual inspection revealed that the MSW consists of high fraction of organics, followed by paper. The soil samples were collected from five trial pits in the dumpsites at depths of 0.5 m, 1 m and 1.5 m. Then the collected soil samples were subjected to specific gravity test, grain size analysis, Atterberg’s limit test,compaction test, direct shear test, California bearing ratio(CBR) test and permeability analysis. The study indicated that the dumpsite soils from four study regions show decreasing trends in the values of maximum dry density(MDD), specific gravity, cohesion and CBR, and increasing permeability as compared to the natural soil. The results show that the geotechnical properties of the soils at all four study locations have been severely hampered due to contamination induced by open dumping of waste.

关键词： Municipal solid waste (MSW) Physical characterization Soil pollution Open dumping Scanning electron microscopy (SEM) Energy disperse X-ray spectroscopy (EDS)

Intermediate Energy Coulomb Excitation of Neutron-Rich Nuclei

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2010年第3期27卷 104-107页

作者： rajiv kumar Rajesh Kharab H. C. sharma Department of Applied Sciences Haryana College of Technology and Management Kaithal-136027 India Department of Physics Kurukshetra University Kurukshetra-136119 India

We reinvestigate the collective effects of the retardation as well as the bending on the Coulomb excitation cross sections and also on the B（E2） strengths of some neutron-rich isotopes using the intermediate energy Coulomb excitation theory. It is found that the B（E2） strengths extracted from the experimental Coulomb excitation cross section data get suppressed approximately by 6%. Furthermore, the obtained B（E2） strengths in the energy range 30-100 MeV/A are found to be in better agreement with the corresponding values known from other sources, than those obtained by using the recoil-corrected relativistic Coulomb excitation theory.

关键词： Nuclear physics

Synthetic and biological studies on a cyclopolypeptide of plant origin

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2008年第5期9卷 391-400页

作者： rajiv DAHIYA Akhilesh kumar Department of Pharmaceutical Chemistry Rajiv Academy for Pharmacy

Objective:A natural cyclic peptide previously isolated from Citrus medica was synthesized by coupling of tetrapep-tide units Boc-Leu-Pro-Trp-Leu-OMe and Boc-Ile-Ala-Ala-Gly-OMe after proper deprotection at carboxyl and amino terminals followed by cyclization of linear octapeptide segment. Methods:Solution phase technique was adopted for the synthesis of cyclooctapeptide-sarcodactylamide. Required tetrapeptide units were prepared by coupling of Boc-protected dipeptides viz. Boc-Leu-Pro-OH and Boc-Ile-Ala-OH with respective dipeptide methyl esters Trp-Leu-OMe and Ala-Gly-OMe. Cyclization of linear octapeptide unit was done by p-nitrophenyl ester method. The structure of synthesized cyclopolypeptide was elucidated by FTIR,1H NMR,13C NMR,FABMS spectral data and elemental analysis. The newly synthesized peptide was evaluated for dif-ferent pharmacological activities including antimicrobial,anthelmintic and cytotoxic activities. Results:Synthesis of sarcodac-tylamide was accomplished with >78% yield utilizing dicyclohexylcarbodiimide(DCC) as coupling agent. Newly synthesized peptide possessed potent cytotoxic activity against Dalton's lymphoma ascites(DLA) and Ehrlich's ascites carcinoma(EAC) cell lines,in addition to moderate anthelmintic activity against earthworms Megascoplex konkanensis,Pontoscotex corethruses and Eudrilus sp. Moreover,cyclopolypeptide displayed good antimicrobial activity against pathogenic fungi Candida albicans and Gram-negative bacteria Pseudomonas aeruginosa,in comparison to standard drugs griseofulvin and ciprofloxacin. Conclusion:Solution phase technique employing DCC and triethylamine(TEA) as base proved to be effective for the synthesis of natural cyclooctapeptide. N-methyl morpholine(NMM) was found to be a better base for the cyclization of linear octapeptide unit in comparison to TEA and pyridine.

关键词： Cyclic octapeptide Citrus medica var. sarcodactylis Sarcodactylamide Peptide synthesis Anthelmintic activity Antimicrobial activity Cytotoxicity

Optical anisotropy and the direction of polarization of exciton emissions in a semiconductor quantum dot:Effect of heavy-and light-hole mixing

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2017年第8期26卷 400-406页

作者： Ranber Singh rajiv kumar Vikramjeet Singh Department of Physics Sri Guru Gobind Singh CollegeSector 26Chandigarh 160019India Department of Physics DAV University JalandharPunjab 144012India IKGPTU Campus HoshiarpurPunjab 146001India

The dependence of the directions of polarization of exciton emissions, fine structure splittings （FSS）, and polarization anisotropy on the light- and heavy-hole （LH-HH） mixing in semiconductor quantum dots （QDs） is investigated using a mesoscopic model. In general, all QDs have a four-fold exciton ground state. Two exciton states have directions of polarization in the growth-plane, while the other two are along the growth direction of the QD. The LH-HH mixing does affect the FSS and polarization anisotropy of bright exciton states in the growth-plane in the low symmetry QDs （e.g., C2v, CS, C1 ）, while it has no effect on the FSS and polarization anisotropy in high symmetry QDs （e.g., C3V, D2d）. When the hole ground state is pure HH or LH, the bright exciton states in the growth-plane are normal to each other. The LH-HH mixing affects the relative intensities and directions of bright exciton states in the growth-plane of the QD. The polarization anisotropy of exciton emissions in the growth-plane of the QD is independent of the phase angle of LH-HH mixing but strongly depends on the magnitude of LH-HH mixing in low symmetry QDs.

关键词： light-heavy hole mixing excitons quantum dots

Catalytic effects of Cu-Co~* on the thermal decomposition of AN and AN/KDN based green oxidizer and propellant samples

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2018年第3期14卷 250-260页

作者： Pratim kumar Puran Chandra Joshi rajiv kumar Shelly Biswas Department of Space Engineering & Rocketry Birla Institute of Technology Department of Mechanical Engineering Vidya Vihar Institute of Technology

This paper presents the catalytic effects of Cu-Co~* catalyst on the decomposition of AN and AN/KDN based oxidizer and propellant samples. Ozawa-Flynn-Wall(OFW) iso-conversional method was used for the kinetic studies and to compute the activation energy(Ea) values for various decomposition steps of the prepared oxidizer and propellant samples in the temperature range of 50 e500C. TG-DTG experiments were carried out for both oxidizer and propellant samples at the heating rates of 3, 5, and 10C/min. AN/KDN based oxidizer samples were prepared by an evaporative co-crystallization method. Citric acid sol-gel method was used for the synthesis of Cu-Co~* catalyst. The propellant sample contains HTPB as the fuel binder along with other ingredients such as TDI, DOA, and Glycerol. The Cu-Co~* catalyst was used as 2% by weight to the total weight of catalyzed oxidizer and propellant samples. It was observed from the present study that, Cu-Co~* catalyst helps in reducing the Ea values for AN and AN based propellant samples. However, with the percentage increment of KDN in the AN crystals, Ea value ***, it was observed that Cu-Co~* catalyst stabilizes the initial partial decomposition of KDN.

关键词：催化氧化剂催化效果热分解 Cu 燃料取样 TG-DTG 催化剂

Analytical modeling of drain current and RF performance for double-gate fully depleted nanoscale SOI MOSFETs

在线全文

学校读者我要写书评

暂无评论

Journal of Semiconductors 2012年第2期33卷 28-35页

作者： rajiv sharma Sujata Pandey Shail Bala Jain Department of Electronics and Communication Engineering Guru Gobind Singh Indraprastha UniversityDelhiIndia Department of Electronics and Communication Engineering Amity UniversitySector-125 NoidaIndia

A new 2D analytical drain current model is presented for symmetric double-gate fully depleted nanoscale SOI *** of device parameters like transconductance for double-gate fully depleted nanoscale SOI MOSFETs is also carried *** this work is concluded by modeling the cut-off frequency, which is one of the main figures of merit for analog/RF performance for double-gate fully depleted nanoscale SOI *** results of the modeling are compared with those obtained by a 2D ATLAS device simulator to verify the accuracy of the proposed model.

关键词： double-gate fully depleted silicon-on-insulator Poisson's equation radio frequency ATLAS

Dynamic analysis and identification of unbalance and misalignment in a rigid rotor with two offset discs levitated by active magnetic bearings:a novel trial misalignment approach

在线全文

学校读者我要写书评

暂无评论

Propulsion and Power Research 2021年第1期10卷 58-82页

作者： Prabhat kumar rajiv Tiwari Department of Mechanical Engineering Indian Institute of Technology GuwahatiGuwahatiAssam781039India

Rotating machinery is an essential and crucial component of numerous mechanical systems in modern industries,transport vehicles,and in several other *** vibrations on rotating equipment due to multiple faults may cause catastrophic failure in machines and lead to hazardous ***,there is a need for perceiving the dynamic nature and identifying the faults for the safe,smooth and effective operation of *** paper proposes a novel trial misalignment approach to estimate the misalignment with a similar concept as the trial unbalance in the rotor *** magnetic bearing(AMB)misalignment with the rotor has been investigated with residual misalignment and additional trial misalignment *** trial misalignments are provided in addition to the unknown misalignments of the residual misalignment *** the execution of this methodology,the dynamic model of a four-degree-of-freedom unbalanced and misaligned rigid rotor with two offset discs supported by two active magnetic bearings has been mathematically *** offset discs result in the gyroscopic effect at high rotor *** of motion of the rotor-AMB system have been derived and solved to generate the time domain rotor displacement and controlling current responses at AMB positions.A fast Fourier transform technique has been utilized to convert the time domain responses into the frequency domain for estimation of unbalance eccentricities and phases together with force-displacement and forcecurrent stiffnesses of misaligned AMBs as well as AMB's constant forces using the developed identification *** values of AMB's parameters for both residual and additional trial misalignment cases are evaluated to estimate the four unknown *** of the algorithm has also been carried out at multiple spin speeds against measurement signal noise in rotor responses and bias errors in rotor system parameters to check its effectiveness

关键词： Misalignment Unbalance Active magnetic bearing Gyroscopic moment Fast Fourier transform Identification

Estimation of composite load model with aggregate induction motor dynamic load for an isolated hybrid power system

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers in Energy 2015年第4期9卷 472-485页

作者： Nitin kumar SAXENA Ashwani kumar sharma Deptment of Electrical Engineering NIT Kumkshetra Haryana 136119 India

It is well recognized that the voltage stability of a power system is affected by the load model and hence, to effectively analyze the reactive power compensation of an isolated hybrid wind-diesel based power system, the loads need to be considered along with the generators in a transient analysis. This paper gives a detailed mathematical modeling to compute the reactive power response with small voltage perturbation for composite load. The composite load is a combination of the static and dynamic load model. To develop this composite load model, the exponential load is used as a static load model and induction motors （IMs） are used as a dynamic load model. To analyze the dynamics of IM load, the fifth, third and first order model of IM are formulated and compared using differential equations solver in Matlab coding. Since the decentralized areas have many small consumers which may consist large numbers of IMs of small rating, it is not realistic to model either a single large rating unit or all small rating IMs together that are placed in the system. In place of using a single large rating IM, a group of motors are considered and then the aggregate model of IM is developed using the law of energy conservation. This aggregate model is used as a dynamic load model. For different simulation studies, especially in the area of voltage stability with reactive power compensation of an isolated hybrid power system, the transfer function AQ/AV of the composite load is required. The transfer function of the composite load is derived in this paper by successive derivation for the exponential model of static load and for the fifth and third order IM dynamic load model using state space model.

关键词： isolated hybrid power system (IHPS) compo- site load model static load dynamic load induction motorload model aggregate load