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RISS 인기검색어
- 검색키워드
- 저자 : Tewari V. K. (검색결과 9 건)
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Gupta Chanchal,Tewari V. K.,Machavaram Rajendra 한국농업기계학회 2022 바이오시스템공학 Vol.47 No.1
Purpose Chili is a spice cumvegetable crop popular for the production of dry chili powder, canned or frozen chili sauces, pickles, etc. However, its conventional manual harvesting practice is time-consuming method and the unavailability of labor during the picking season causes a delay in the harvesting period which directly impart poor-quality product. Methods In this study, a comb-type picking mechanism was developed for multiple-pass harvesting and the optimal working conditions were evaluated considering picking mechanism rotational speed and plant conveying speed. The comb-type picking mechanismwas designed by considering the physical and mechanical properties of chili cultivar and the laboratory setup consists of a plant conveying system, picking mechanism, real-time operating system (RTOS), and power transmission system. Results Picking efficiency increased significantly under higher picking unit rotational speeds and lower plant conveying speed. On the other side, chili pepper damage decreased significantly under lower picking unit rotational speeds and higher plant conveying speed. The plant conveying speed was 1.47 km/h and rotational speed of picking unit was 177.55 rpm considered for optimum performance output with a maximum picking efficiency of 78.17 % and minimum chili pepper damage of 2.62 %. Conclusions It has been observed that the comb-type picking mechanism was efficient in picking of chili pepper from chili plant with a maximum picking efficiency at optimal settings. Further retrofitting of such picking unit to a self-propelled agriculture machine to harvest chili pepper in actual field conditions and a replacement to conventional harvesting process.
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Modification of Reactive Muffler in Farm Tractor to Reduce Noise Level Using Finite Element Method
Kumar Naveen,Tewari V. K. 한국농업기계학회 2023 바이오시스템공학 Vol.48 No.2
Purpose The improvement in transmission loss (TL) in the target frequency band is the primary goal of exhaust muffl er design. The non-refl ective boundary conditions are simulated, and the transmission loss is calculated using the fi nite element method. Methods By modifying structural elements such as the expansion diameter, expansion length, open area ratio, and baffl e plate, the reactive muffl er used in the farm tractor was given an improved TL using the fi nite element method (FEM). Improved muffl ers’ noise emission was tested and compared to that of an existing reactive-type muffl er. The tests were conducted in accordance with ISO 7216 and ISO 5131, the worldwide requirements for product noise emissions while considering diff erent types of exhaust systems, location of the sound level meter, engine speed, and operating gear. The collected data was examined using a factorial test that was based on a fully randomized design. Results The modifi ed muffl er-2’s TL in the frequency range of 0–2000 Hz increased on average by 22.75 dB in comparison to the existing reactive-type muffl er. According to the outcomes of a completely randomized design, the primary infl uences of engine speed, gear position, and exhaust type on the noise produced by tractors were found to be signifi cant at a 5% level of signifi cance. Modifi ed muffl er-2 decreased tractor sound pressure level for a range of 2.26–3.03 dBA in all treatments. Conclusions Structural modifi cation in reactive muffl er based on FEM helped in improving transmission loss which results in the reduced sound pressure level of the tractor.
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Raikwar Satyam,Tewari V. K. 한국농업기계학회 2023 바이오시스템공학 Vol.48 No.2
Purpose A tractor is a versatile machine and is used in many applications other than agriculture, like in mining, transportation, and construction. One such application is with front end loader where it requires a frequent change in direction of motion. To meet this requirement a power shuttle transmission system is used in agricultural tractors. The present research focuses on the transmission control algorithm development for one such a power shuttle transmission system. Methods The development and testing of the control algorithm were carried out in MATLAB & Simulink environments with an additional specifi c strategy for the clutch pressure modulation. Further National Instruments CompactRIO (NI-cRIO) was used to verify the system’s functionality in a real-time environment. Results The obtained simulation results were in close accordance with the real system in terms of system functionality and response time. The alikeness between the simulated and actual response time varies from − 20 to 11% and the tractor intended functionality is verifi ed as per the developed control logic. Conclusion This research provides an approach for the development of control strategies for tractor transmission systems and their rapid prototype development and testing.
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Kumari Sweeti,Tewari V. K.,Kumar Sanjeev,Sahni Ramesh K. 한국농업기계학회 2023 바이오시스템공학 Vol.48 No.4
Purpose An electromyography (EMG) study was conducted during push and pull operations to evaluate the muscle fatigue of agricultural farm workers. Methods Twelve medically fit agricultural workers were selected for evaluation of muscular activity during push–pull operations, with the help of a laboratory setup, which was developed based on the ergonomic criteria of the uniform force application. The most used muscle during push and pull operation (middle deltoid MD, triceps brachii TR, brachioradialis BR, and biceps brachii BI) was selected for an EMG study. The uniform force or load (50, 100, 150, and 200 N) was applied during the experiment. Results The most activated or used muscles during the pushing and pulling operation were TR and BR, respectively. The activity of the middle deltoid and triceps brachii muscles was more during the pushing than the pulling task. Conclusion Root mean square (RMS) values for EMG activity were found to increase with increasing load in all the selected muscles, indicating that muscular loads were affected by the external load. A load of 200 N was found difficult to operate compared to other selected loads for push–pull operation for all the subjects. The TR muscle gets more fatigued during pushing because it is responsible for elbow extension, which is a primary movement in pushing. The BR muscle gets more fatigued because it is more activated during pull force application.
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Panwar, Varij,Gill, Fateh Singh,Rathi, Vikas,Tewari, V.K.,Mehra, R.M.,Park, Jong-Oh,Park, Sukho Elsevier 2017 Materials chemistry and physics Vol.193 No.-
<P><B>Abstract</B></P> <P>The fabrication of strong conducting composite sheets (CCSs) using a simple technique with cost-effective materials is desirable for capacitor, decoupling capacitor, and electromagnetic interference (EMI) shielding applications. Here, we used cost-effective graphite flakes (GFs) as a conducting filler and amorphous poly (styrene-co-acrylonitrile) (PSAN) as an insulating polymer to fabricate a CCS via a simple mechanical mixing and hot compression molding process in 2.5 h, with the aim to save time and avoid the use of toxic reagents, which are generally used in chemical methods. In the present method, the GFs are connected in diffusively adhere polymer matrix, controlled by temperature and pressure that generate the conduction in the CCSs. The resulting PSAN/GF CCSs were characterized by using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and hardness tests. The GFs penetrated the interfacial region of PSAN, thus improving the thermistor and dielectric properties (dielectric constant, AC conductivity, and dissipation factor) of the PSAN/GF CCSs. Furthermore, the PSAN/GF CCSs showed enhanced hardness and EMI shielding effectiveness (SE) properties in the X-band frequency range (8.5–12.5 GHz). The percolation theory was implemented to DC and AC conductivity. To detect the transition of the dielectric properties, the dielectric constant of the CCSs was analyzed with increasing volume fraction of GFs in the radio frequency region. The improved dielectric constant, AC conductivity, and dissipation factor of the PSAN/GF CCS, indicated a significant improvement in their EMI shielding properties in the X-band frequency range, which were measured using the waveguide method. The ac conductivity of PSAN/GF CCS shows stable behavior in the higher frequency ranges. The EMISE of PSAN/GF CCS were found to increase with increasing GF content due to the absorbance mechanism.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Enhanced hardness and thermal stability of PSAN/GF conducting composite sheet (CCS). </LI> <LI> Enhanced dielectric and electromagnetic interference shielding of PSAN/GF CCS. </LI> <LI> Cost-effective and fast fabrication method of PSAN/GF CCS. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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Suman Paik,N. Naveen Kumar,B. K. Dutta,R. Tewari,P. V. Durgaprasad 대한금속ᆞ재료학회 2023 METALS AND MATERIALS International Vol.29 No.2
This article investigates the deformation behaviour and fracture characteristics of copper single crystals by uniaxial tensileexperiments and compares the results with crystal plasticity simulations. Quasi-static tensile tests were carried out toinclude different stress–strain states by varying the crystal orientation with respect to specimen axis after determining theinitial orientation by Electron Backscatter Diffraction. The different ductile modes of failure of single crystals due to shearafter loading were examined. Thereafter, by employing the scanning electron microscopy and theoretical slip trace analysis,orientations of slip traces of deformed crystals were determined. Experimental results were then rationalised by performingcrystal plasticity finite element simulations, presuming cross-slip and associated dislocation dissociation into partials playan influential role on the orientation dependence of the material. A continuum ductile damage criterion was coupled withplasticity on capturing the slip localisation caused by material softening. Comparison between experimentally measuredand numerically obtained stress–strain data, texture evolution and fracture angles were subsequently evaluated. An evaluationhas also been made by comparing the identities of active slip modes attained from experiments with that of determinedfrom simulations.
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Suman Paik,N. Naveen Kumar,B. K. Dutta,R. Tewari,P. V. Durgaprasad 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.3
This article investigates the deformation behaviour and fracture characteristics of copper single crystals by uniaxial tensileexperiments and compares the results with crystal plasticity simulations. Quasi-static tensile tests were carried out toinclude different stress–strain states by varying the crystal orientation with respect to specimen axis after determining theinitial orientation by Electron Backscatter Diffraction. The different ductile modes of failure of single crystals due to shearafter loading were examined. Thereafter, by employing the scanning electron microscopy and theoretical slip trace analysis,orientations of slip traces of deformed crystals were determined. Experimental results were then rationalised by performingcrystal plasticity finite element simulations, presuming cross-slip and associated dislocation dissociation into partials playan influential role on the orientation dependence of the material. A continuum ductile damage criterion was coupled withplasticity on capturing the slip localisation caused by material softening. Comparison between experimentally measuredand numerically obtained stress–strain data, texture evolution and fracture angles were subsequently evaluated. An evaluationhas also been made by comparing the identities of active slip modes attained from experiments with that of determinedfrom simulations.
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Development of a Triggering Arrangement For the KALI-30GW MARX Generator
S. Mitra,T. S. Kolge,Ritu Agarwal,P. C. Saroj,Ankur Patel,K. Senthil,Vishnu Sharma,S. V. Tewari,Archana Sharma,K. C. Mittal 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.4
This paper reports the design methodology and implementation experiments for a solid-statebasedtriggering arrangement for the MARX generator of the KALI-30GW (1 MV, 30 kA, 80 ns)pulsed power system. The 15-stage bipolar MARX generator of the KALI-30GW system is triggeredusing a trigatron-type spark gap. An insulated-gate bipolar-transistor (IGBT)-based trigger supplyis used to trigger the first spark gap, and the next two spark gaps are triggered by using internallygeneratedtrigger pulses. Optically-isolated arrangements are provided for a human interface. Theentire assembly was tested with a dummy copper sulphate load, and an excellent triggering rangeof 7 − 12 kV was achieved. The circuit diagram, analysis and experimental results of the triggeringarrangement are presented in the paper.
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