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Mechanical properties of friction stir welded armor grade Al-Zn-Mg alloy joints

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Transactions of Nonferrous Metals Society of China 2017年第3期27卷 493-506页

作者： C.SHARMA V.UPADHYAY D.K.dwivedi P.KUMAR Rustamji Institute of Technology BSF AcademyTekanpurGwaliorMadhyapradesh 475005India Mechanical Engineering Department National Institute of Technology PatnaPatna 800005India Mechanical and Industrial Engineering Department I.I.T.RoorkeeUttarkhand 247667India

The influence of different welding speeds and rotary speeds on the formation and mechanical properties of friction stirweld joints of armor grade aluminum alloy was *** developed weld joints were characterized by bend tests,micro-hardness tests,tensile tests,optical and scanning electron *** properties(i.e.,micro-hardness,ultimatetensile strength and elongation to fracture)increased with the increase in rotary speed or decrease in welding *** effect ofwelding speed on micro-hardness of heat affected zones was more profound than the rotary *** welding speeds and rotaryspeeds influenced the mechanical properties and their effects on various mechanical properties of the friction stir welded joints canbe predicted with the help of regression models.

关键词： friction stir welding welding parameters mechanical properties fractography regression modeling

Si–Ge based vertical tunnel field-effect transistor of junction-less structure with improved sensitivity using dielectric modulation for biosensing applications

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Chinese Physics B 2023年第12期32卷 644-651页

作者： Lucky Agarwal Varun Mishra Ravi Prakash dwivedi Vishal Goyal Shweta Tripathi School of Electronics Engineering Vellore Institute of TechnologyChennai 600127India Department of Electronics and Communication Engineering Graphic Era(deemed to be University) DehradunUttarakhand 248002India Department of Electronics and Communication Engineering GLA UniversityMathura 281406India Department of Electronics and Communication Engineering Motilal Nehru National Institute of TechnologyAllahabad 211004India

A dielectric modulation strategy for gate oxide material that enhances the sensing performance of biosensors in junction-less vertical tunnel field effect transistors(TFETs)is *** junction-less technique,in which metals with specific work functions are deposited on the source region to modulate the channel conductivity,is used to provide the necessary doping for the proper functioning of the *** simulation studies of the proposed structure and junction structure have been compared,and showed an enhanced rectification of 10^(4) *** proposed structure is designed to have a nanocavity of length 10 nm on the left-and right-hand sides of the fixed gate dielectric,which improves the biosensor capture area,and hence the *** considering neutral and charged biomolecules with different dielectric constants,TCAD simulation studies were compared for their *** off-state current IOFFcan be used as a suitable sensing parameter because it has been observed that the proposed sensor exhibits a significant variation in drain ***,it has been investigated how positively and negatively charged biomolecules affect the drain current and threshold *** explore the device performance when the nanogaps are fully filled,half filled and unevenly filled,extensive TCAD simulations have been *** proposed TFET structure is further benchmarked to other structures to show its better sensing capabilities.

关键词： biomolecules high-k dielectric junction-less vertical tunnel field effect transistor(TFET)

An Exploratory Study of Experimental Tools for Wireless Sensor Networks

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Wireless Sensor Network 2011年第7期3卷 215-240页

作者： A.K. dwivedi O.P. Vyas 不详

The objective of this contribution is to present expositive review content on currently available experimental tools/services/concepts used for most emerging field Wireless Sensor Network that has capability to change many of the Information Communication aspects in the upcoming era. Currently due to high cost of large number of sensor nodes most researches in wireless sensor networks area is performed by using these experimental tools in various universities, institutes, and research centers before implementing real one. Also the statistics gathered from these experimental tools can be realistic and convenient. These experimental tools provide the better option for studying the behavior of WSNs before and after implementing the physical one. In this contribution 63 simulators/simulation frameworks, 14 emulators, 19 data visualization tools, 46 testbeds, 26 debugging tools/services/concepts, 10 code-updation/reprogramming tools and 8 network monitors has been presented that are used worldwide for WSN researches.

关键词： Experimental tools Simulation Emulation Testbed Data visualization Debugger Network Monitor Code-updater Wireless Sensor Network

Characteristics of fog in relation to tropical cyclone intensity: A case study for IGI airport New Delhi

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Tropical Cyclone Research and Review 2021年第3期10卷 170-181页

作者： Rizwan Ahmed Narendra G.Dhanger Suneet dwivedi Ram Kumar Giri Prakash Pithani Sachin D.Ghude University of Allahabad-UP India India Meteorological Department Ministry of Earth Sciences New DelhiIndia Indian Institute of Tropical Meteorology Pashan-PuneIndia Andhra University VisakhapatnamAndhra PradeshIndia

Widespread catastrophic fog episodes in polluted northern India have been attributed to tropical cyclone activity in the Bay of Bengal&Arabian Sea;however,limited studies have been conducted on the effect of tropical cyclone intensity(’T’Numbers)on different fog characteristics in Indo Gangetic Basin,Northern *** this study,different characteristics,including persistence,intensity,and areal extension,were analyzed at the Indira Gandhi International Airport,New Delhi during 1998-99,2013-14,and 2016-17.A high-intensity tropical cyclone(Severe to Very Severe Cyclonic Storm)has been found to significantly increase the persistence,intensity,and areal extension of fog by inducing strong subsidence over the IGI Airport/Indo-Gangetic *** knowledge is vital for improving the short-term forecasting of fog in the IndoGangetic Basin of Northern India and will further support the Government agencies to take preventive safety measures and planning well in advance time.

关键词： Fog Tropical cyclone Indo-gangetic basin(IGB) Fog intensity

Pongamia as a Source of Biodiesel in India

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Smart Grid and Renewable Energy 2011年第3期2卷 184-189页

作者： Gaurav dwivedi Siddharth Jain Mahendra Pal Sharma 不详

Pongamia Pinnata trees are normally planted along the highways, roads, canals to stop soil erosion. Billions of trees exist all over India. If the seeds fallen along road side are collected, and oil is extracted at village level expellers, few million tons of oil will be available for Lighting the Lamps in rural area. It is the best substitute for Kerosene. Since these are spread over a large area, collection of seeds for Biodiesel manufacture is not viable. (A compact plantation can support a Biodiesel plant. The seedlings of Pongamia can survive in 1.5 meters deep water submergence / inunda-tion for five to six months duration at a stretch. There are nearly 30,000 square km of water reservoirs in India. This tree can be cultivated in our water storage reservoirs up to 1.5 meters depth and reap additional economic value from unused reservoir lands. The estimated annual production of oil from its seeds is about 50,000 t. The oil has not yet found any significant commercial application. But due to increase in awareness and growth in research in this area the Pongamia it can be developed as the alternative source of fuel by replacing diesel. In the present study attempt has been made to study the scope of Pongamia in India.

关键词： Pongamia Biodiesel Viscosity Density Flashpoint

Non-Communicating inactive rudimentary horn of the uterus presenting with dysmenorrhoea—a case report of successful laparoscopic excision

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Open Journal of Obstetrics and Gynecology 2011年第4期1卷 213-216页

作者： Rachana dwivedi Keerthi Perera Padma Eedarapalli 不详

Uterine developmental abnormalities can cause both obstetric and gynaecological complications. Non-functioning rudimentary uterine horn is a rare cause of dysmenorrhoea which usually starts after menarche. Cases with lateral/inferior arrangement of blood supply to the functioning rudimentary horn and lapascopic removal have been described in literature. Ours is a unique case of non-functioning rudimentary horn with an unusual medial arrangement of vasculature successfully treated by laparoscopic excision. We also present a brief review of the literature. The patient presented with irretractable dysmenorrhoea despite hormonal manipulation and analgesics. Following the diagnosis using laparoscopy and hysteroscopy and MRI, the left sided non-communicating rudimentary horn with inactive endometrium was removed laparoscopically. Her symptoms were resolved and this was followed by successful pregnancies. Diagnosis of rudimentary horn with inactive endometrium is difficult. Ultrasound is unreliable. MRI, 3D CT scan and 3D ultrasound are gaining popularity. Accurate, prior identification of the type using laparoscopy and hysteroscopy if necessary is essential. This helps in surgical planning. The laparoscopic approach is increasingly being used to resect these horns due to its safety and merits.

关键词： Dysmenorrhoea Rudimentary Horn Laparoscopic Excision

Estimating the impact of antenatal care visits on institutional delivery in India: A propensity score matching analysis

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Health 2013年第5期5卷 862-878页

作者： Priyanka Dixit Laxmi Kant dwivedi Faujdar Ram Department of Mathematical Demography & Statistics International Institute for Population Sciences Mumbai India International Institute for Population Sciences Mumbai India

Literature asserts that prenatal care is an imperative factor for subsequent health care utilization. However, in the Indian settings presence of selection bias while determining the impact of ANC visits on institutional delivery has been overlooked by the researchers. Therefore this paper aims to examine the net impact of ANC visits on subsequent utilization of institutional delivery after removing the presence of selection bias using recent round of National Family Health survey data. The analysis has been carried out in two separate models, in the first model 1-2 ANC visits been compared with no visit and in the second model three or more antenatal care visits with no visit. The propensity score matching analysis used in this study sheds new light into this line of research which provides an effective strategy for controlling the confounding influence of institutional delivery. Employing the propensity score matching estimation approach we found women who made 1-2 ANC visits had 6.6 percent higher chance to deliver in an institution compared to women who made no visit. In addition, if a woman visited health centre three or more than three times, her chances were 31 percent higher to deliver in an institution. Result based on sensitivity analysis suggests that selection bias on unobserved covariates would have to be around 40 percent to alter the impact of 1-2 ANC visits. Findings suggest that interventions which plan to increase institutional delivery should target pregnant women who come for ANC checkups at institution first time, and health workers should encourage women to return to the health centre for more numbers of visits, as our results indicate that three or more ANC visits significantly change the women’s attitudes towards institutional delivery.

关键词： Antenatal Care Institutional Delivery Selection Bias Matching Analysis India

Effects of roller burnishing process parameters on surface roughness of A356/5%SiC composite using response surface methodology

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Advances in Manufacturing 2014年第4期2卷 303-317页

作者： Shashi Prakash dwivedi Satpal Sharma Raghvendra Kumar Mishra Gautam Buddha University Greater NoidaGautam Budh NagarU.P.201310India

In this study, a simple roller burnishing tool was made to operate burnishing processes on A356/5%SIC metal matrix composite fabricated by electromagnetic stir casting under different parameters. The effects of burnishing speed, burnishing force and number of burnishing passes on the surface roughness and tribological properties were measured. Scanning electron microscopy （SEM） graphs of the machined surface with PCD （insert-10） tool and roller burnished surface with tungsten carbide （WC） roller were taken into consider- ation to observe the surface finish of metal matrix composites. The mechanical properties （tensile strength, hardness, duc- tility） of A356/5%SIC metal matrix composites were studied for both unburnished samples and burnished samples. The results revealed that the roller burnished samples of A356/ 5%SIC led to the improvement in tensile strength, hardness and ductility. In order to find out the effects of roller bur- nishing process parameters on the surface roughness of A356/ 5%SIC metal matrix composite, response surface methodol- ogy （RSM）（Box-Behnken design） was used and a prediction model was developed relevant to average surface roughness using experimental data. In the range of process parameters, the result shows that roller burnishing speed increases, and surface roughness decreases, but on the other hand roller burnishing force and number of passes increase, and surface roughness increases. Optimum values of burnishing speed （1.5 m/s）, burnishing force （50 N） and number of passes （2） during roller burnishing of A356/5%SIC metal matrix com- posite to minimize the surface roughness （predicted 1.232 μm） have been found out. There was only 5.03% error in the experimental and modeled results of surface roughness.

关键词： Burnishing speed Burnishing force Response surface methodology (RSM) Box-Behnkendesign Desirability function

Heat-treated Nickel Alloys Produced Using Laser Powder Bed Fusion-based Additive Manufacturing Methods:A Review

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Chinese Journal of Mechanical Engineering(Additive Manufacturing Frontiers) 2023年第3期2卷 55-68页

作者： Aman dwivedi M K Khurana Y G Bala Department of Mechanical Engineering Motilal Nehru National Institute of Technology AllahabadPrayagraj211004India

Laser powder bed fusion(LPBF)is the most widely used metal additive manufacturing *** is a novel layer-by-layer manufacturing technique based on a geometrical model that provides a suitable alternative for material *** mode is widely used in laser and electron beam ***(Ni)alloy prepa-ration using the LPBF method has attracted considerable attention in several areas,owing to the high corro-sion resistance and good mechanical properties of the prepared *** specific conditions of solidification through the metal fused during the selective laser fusion process and its layer deposition induces microstruc-tural peculiarities,including the formation of a supersaturated solid solution,extreme microstructural refine-ment,and the generation of residual ***,heat treatment and hot isostatic pressing,which are generally applied to conventionally manufactured Ni alloys,may need to be altered to adapt to the met-allurgical properties of Ni alloys manufactured using direct metal laser deposition and address particular is-sues resulting from the process *** studies have been conducted on this topic over the past few years,suggesting different approaches for addressing different alloying *** review summarizes the latest scientific findings in the area of thermal treatment for selective laser sintering of additively manufactured Ni alloys.

关键词： Additive manufacturing Laser powder bed fusion Nickel alloys Process parameters Heat treatment Mechanical properties