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A Developed H-Bridge Cascaded Multilevel Inverter with Reduced Switch Count
Ponraj Ram Prakash,Sigamani Titus,Subramanian Vijayalakshmi 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.3
Multilevel Inverter integrates several Direct Current (DC) sources to produce a single-phase Alternating Current (AC) waveform that can be used to meet the domestic and commercial power demand. This article introduces a novel Multi Source Cascaded Multilevel Inverter with a reduced number of switches for the effi cient use of DC voltage sources. The conversion effi ciency can be increased by the presented topology which is simple in design to overcome the signifi cant switching losses in the power electronics devices. Optimal Firing Angle and Phase Opposition Disposition Pulse width Modulation Techniques were used to reduce the harmonics at the desired output of the inverter and also to improve the power quality of the presented topology. This article also proposes two Asymmetric Multilevel Inverter Topologies. A comparison has been made, on the number of switches required and the effi ciency of the inverters to diff erentiate the presented Topologies from other topologies of the multilevel inverter. Finally, the performance characteristics of the presented topologies have been designed and investigated using MATLAB Simulation. Simulation results were validated using an experimental setup.
Analysis of Multi-Input Multilevel Boost Inverter Circuit with Optimal Firing Angles Using dSPACE
Ponraj Ram Prakash,Sigamani Titus,Ravindran Vijay 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.2
The DC load utilities are increased due to the modern development of alternate renewable Energy sources and Electric Vehicles. Contemporary applications like Electric Vehicles require multiple voltages that require separate DC-DC converters. Usage of more power electronic converters for multiple loads leads to more harmonics and high switching loss. To minimize the losses and improve efficiency, this paper presents a new multilevel inverter topology with multiple outputs and multiple inputs. This circuit combines a multi-input multistage DC-DC converter for various DC voltage levels and a level shifter circuit with H-Bridge. The performance of the circuit was analysed using Phase opposition and disposition modulation and optimal firing angle PWM techniques. Pulses for DC-DC converter and multilevel inverter are generated using MATLAB/Simulink environment and integrated with hardware prototype using dSPACE- ds1104 interface.
Vibration upshot of operating mechanical sewing machine
Prakash Kumar Yadav,Ram Lochan Yadav,Deepak Sharma,Dev Kumar Shah,Niraj Khatri Sapkota,Dilip Thakur,Nirmala Limbu,Md Nazrul Islam 대한직업환경의학회 2017 대한직업환경의학회지 Vol.29 No.-
Background: Most of the people associated with tailoring occupation in Nepal are still using mechanical sewing machine as an alternative of new technology for tailoring. Common peroneal nerves of both right and left legs are exposed to strenuous and chronic stress exerted by vibration and paddling of mechanical sewing machine. Methods: The study included 30 healthy male tailors and 30 healthy male individuals. Anthropometric variables as well as cardio respiratory variables were determined for each subject. Standard Nerve Conduction Techniques using constant measured distances were applied to evaluate common peroneal nerve (motor) in both legs of each individual. Data were analyzed and compared between study and control groups using Man Whitney U test setting the significance level p ≤ 0.05. Results: Anthropometric and cardio respiratory variables were not significantly altered between the study and control groups. The Compound muscle action potential (CMAP) latency of common peroneal nerves of both right [(11.29 ± 1.25 vs. 10.03 ± 1.37), P < 0.001] and left [(11.28 ± 1.38 vs. 10.05 ± 1.37), P < 0.01] legs was found to be significantly prolonged in study group as compared to control group. The Amp-CMAP of common peroneal nerves of both right [(4.57 ± 1.21 vs. 6.22 ± 1.72), P < 0.001] and left [(4.31 ± 1.55 vs. 6.25 ± 1.70), P < 0.001] legs was found significantly reduced in study group as compared to control group. Similarly, the motor nerve conduction velocity (MNCV) of common peroneal nerves of both right [(43.72 ± 3.25 vs. 47.49 ± 4.17), P < 0.001] and left [(42.51 ± 3.82 vs. 46.76 ± 4.51), P < 0.001] legs was also found to be significantly reduced in study group in comparison to control group. Conclusion: Operating mechanical sewing machine by paddling chronically and arduously could have attributed to abnormal nerve conduction study parameters due to vibration effect of the machine on right and left common peroneal nerves. The results of present study follow the trend towards presymptomatic or asymptomatic neuropathy similar to subclinical neuropathy.
Disturbance, Diversity, Regeneration and Composition in Temperate Forests of Western Himalaya, India
Om Prakash Tiwari,Chandra Mohan Sharma,Yashwant Singh Rana,Ram Krishan 강원대학교 산림과학연구소 2019 Journal of Forest Science Vol.35 No.1
We have investigated the impact of anthropogenic and natural disturbances on regeneration, composition and diversity in some temperate forests of Bhagirathi Catchment Area of Garhwal Himalaya. The forests were categorized on the basis of canopy cover and magnitude of disturbance into highly, moderately and least disturbed classes. The dominant tree species at lower elevation were Pinus roxburghii and Quercus leucotrichophora, while Abies pindrow, Q. semecarpifolia and Rhododenron arboreum were the dominant species at the upper elevational forests. Cythula tomentosa and Indegophera heterentha were the dominant shrub species present in all the forests. Similarly, Circium wallichii and Oxalis corniculata were the dominant herb species found in all forests (except Q. leucotrichophora forest), whereas Thalictrum foliolosum and Viola pilosa were noticed in each forest (except P. roxburghii forest). The tree density values oscillated between 400±10 trees ha-1 to 750±89.1 trees ha-1 which generally decreased from lower to higher disturbance regimes however, the total basal cover value was highest (88.1±23.6 m2 ha-1) in highly disturbed forest and lowest (25.8±2.2 m2 ha-1) in moderately disturbed forest. The shrub and herb densities were maximum in least disturbed forest, while the young regenerating individuals i.e., sapling and seedling were observed increasing from high to low disturbed forests which reflected that the forest fragmentation adversely affected the regeneration. However, A. pindrow and P. roxburghii were found invariably encroaching the habitats of R. arboreum and Q. leucotrichophora at various altitudes, respectively. The Canonical Correspondence Analysis clearly indicated that the elevation and lopping intensity have more impact on trees, while shrub and herbs were more influenced by elevation, canopy cover, light attenuation and soil erosion. Pinus roxburghii was the only species which was affected by heavy litter removal and forest fire.
Om Prakash Tiwari,Yashwant Singh Rana,Ram Krishan,Chandra Mohan Sharma,Bhupendra Singh Bhandari 한국산림과학회 2018 Forest Science And Technology Vol.14 No.2
The present study aimed to analyze the regeneration dynamics, population structure, and forest composition in some ridge forests of the Western Himalaya to elucidate the impact of climate change. The highest species richness (trees, 17; saplings, 16; seedlings, 16) was recorded in mixed Rhododendron arboreum forest. The maximum tree density (737 § 25.93 trees ha¡1; mixed Quercus floribunda); sapling density (5342 § 587.54 saplings ha¡1; mixed Quercus semecarpifolia), and seedling density (71,429 § 26,632.29 seedlings ha¡1; mixed Cedrus deodara) were recorded in forests of higher altitudes. The mean basal cover values in these forests oscillated between 39.21 § 1.53 m2 ha¡1 (mixed Quercus leucotrichophora) to 87.65 § 15.45 m2 ha¡1 (mixed Abies pindrow). The highest Shannon index value (0.51 § 0.05) and species evenness (0.36 § 0.02) for trees were recorded in mixed Rhododendron arboreum forest. Some species like Betula utilis, Myrica esculenta, Ficus rumphii, Ilex dipyrena, Quercus floribunda, Litsea elongata, Symplocos paniculata, and Abies spectabilis were noticed as new recruiters (recent invaders) in new habitats, which may change the future forest composition. This study revealed that ridge forests of the Bhagirathi catchment area were in transition phase at middle altitudes. Mixed Quercus floribunda forest was observed to be the youngest regenerating forest; however, mixed Abies pindrow forest was the most mature old-growth forest.
Techniques for Formulation of Nanoemulsion Drug Delivery System: A Review
Manish Kumar,Ram Singh Bishnoi,Ajay Kumar Shukla,Chandra Prakash Jain 한국식품영양과학회 2019 Preventive Nutrition and Food Science Vol.24 No.3
Nanoemulsion drug delivery systems are advanced modes for delivering and improving the bioavailability of hydrophobic drugs and the drug which have high first pass metabolism. The nanoemulsion can be prepared by both high energy and low energy methods. High energy method includes high-pressure homogenization, microfluidization, and ultrasonication whereas low energy methods include the phase inversion emulsification method and the self-nanoemulsification method. Low energy methods should be preferred over high energy methods as these methods require less energy, so are more efficient and do not require any sophisticated instruments. However high energy methods are more favorable for food grade emulsion as they require lower quantities of surfactant than low energy methods. Techniques for formulation of nanoemulsion drug delivery system are overlapping in nature, especially in the case of low energy methods. In this review, we have classified different methods for formulation of nanoemulsion systems based on energy requirements, nature of phase inversion, and self-emulsification.