Screen generic lightlike submersions

Gaurav Sharma,Sangeet Kumar,Dinesh Kumar Sharma 호남수학회 2023 호남수학학술지 Vol.45 No.4

We introduce the study of a new class of a lightlike submersion ϕ : K1 → K′ from a screen generic lightlike submanifold of an indefinite Kaehler manifold K2 onto an indefinite almost Hermitian manifold K′, and show that for this case K′ must be an indefinite Kaehler manifold. Then, we derive a relationship between the holomorphic sectional curvatures of K2 and K′ . Finally, we present a classification theorem for a screen generic lightlike submersion, giving the relationship between the sectional curvatures of the total space K2 and the fibers.

Three-Phase 4-Wire Isolated Wind Energy Conversion System Employing VSC with a T-Connected Transformer for Neutral Current Compensation

Gaurav Kumar Kasal,Bhim Singh 대한전기학회 2009 Journal of Electrical Engineering & Technology Vol.4 No.2

This paper presents a voltage and frequency controller (VFC) for a 4-wire stand-alone wind energy conversion system (WECS) employing an asynchronous generator. The proposed VF controller consists of a three leg IGBT (Insulated Gate Bipolar Junction Transistor) based voltage source converter and a battery at its DC bus. The neutral terminal for the consumer loads is created using a Tconnected transformer, which consists of only two single phase transformers. The control algorithm of the VF controller is developed for the bidirectional flow capability of the active power and reactive power control by which it controls the WECS voltage and frequency under different dynamic conditions, such as varying consumer loads and varying wind speeds. The WECS is modeled and simulated in MATLAB using Simulink and PSB toolboxes. Extensive results are presented to demonstrate the capability of the VF controller as a harmonic eliminator, a load balancer, a neutral current compensator as well as a voltage and frequency controller.

H-Bridge VSC with a T-Connected Transformer for a 3-Phase 4-Wire Voltage and Frequency Controller of an Isolated Asynchronous Generator

Gaurav Kumar Kasal,Bhim Singh 전력전자학회 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.1

This paper deals with a novel solid state controller (NSSC) for an isolated asynchronous generator (IAG) feeding 3-phase 4-wire loads driven by constant power prime movers, such as uncontrolled pico hydro turbines. AC capacitor banks are used to meet the reactive power requirement of the asynchronous generator. The proposed NSSC is realized using a set of IGBTs (Insulated gate bipolar junction transistors) based current controlled 2-leg voltage source converters (CC-VSC) and a DC chopper at its DC bus, which keeps the generated voltage and frequency constant in spite of changes in consumer loads. The neutral point of the load is created using a T-configuration of the transformers. The IAG system is modeled in MATLAB along with Simulink and PSB (power system block set) toolboxes. The simulated results are presented to demonstrate the capability of the isolated generating system consisting of NSSC and IAG driven by uncontrolled pico hydro turbine and feeding 3-phase 4-wire loads.

Acupuncture for Management of Endodontic Emergencies: a Review

Kumar Gaurav,Tewari Sanjay 사단법인약침학회 2023 Journal of Acupuncture & Meridian Studies Vol.16 No.1

Root canal treatment (RCT) employed for painful endodontic conditions like apical periodontitis and irreversible pulpitis is associated with a high incidence of postoperative pain. Pharmacological management for this purpose is effective, but not entirely free from side effects and in some cases may fail to provide adequate relief. Furthermore, concerns have been raised regarding the transmission of coronavirus disease-2019 (COVID-19) as a result of the aerosols generated and prolonged chair side time required for RCT. Acupuncture is a traditional Chinese therapy commonly employed as an alternative for the treatment of pain. And what’s more, the use of acupuncture has been recently reported as treatment for the management of endodontic pain as well as on the anesthetic success in patients with irreversible pulpitis. This review aims to evaluate the current evidence for acupuncture in endodontics and its potential role in emergency pain relief and management for patients. To combat this, a thorough search for literature within the field was performed in five electronic databases. Retrieved studies were screened according to the pre-defined eligibility criteria. After both an electronic and manual search, five studies were selected for review. These studies reported the beneficial effects of acupuncture in reducing the failure of nerve block in patients with irreversible pulpitis and in controlling both intraoperative and postoperative pain following RCT. In addition, it was also reported to reduce anxiety surrounding the dental procedure and minimized the intake of analgesics after the endodontic procedure, which can result in some unwanted side effects. However, more in depth clinical research is required before any recommendation regarding the application of acupuncture in endodontic patients can be made.

Effect of premedication on postoperative pain after root canal therapy in patients with irreversible pulpitis: a systematic review and meta-analysis

Kumar, Gaurav,Sangwan, Pankaj,Tewari, Sanjay The Korean Dental Society of Anesthsiology 2021 Journal of Dental Anesthesia and Pain Medicine Vol.21 No.5

This systematic review aimed to assess the effect of premedication on postoperative pain after root canal treatment in vital teeth. Five electronic databases were searched for randomized clinical trials, and two independent reviewers selected eligible studies, extracted data, and assessed the quality of studies using the Cochrane Risk of Bias tool. Meta-analysis was conducted using the random-effects model, and the pooled effect estimate of the standardized mean difference (SMD) between premedication and placebo was calculated. Subgroup analysis was conducted based on the class and route of the drug. Studies with a high risk of bias were excluded from the sensitivity analysis. Ten trials satisfied the inclusion criteria, of which eight were included in the meta-analysis. Premedication was more effective in reducing postoperative pain than placebo at 6 hours (SMD = -1.00; 95% confidence interval [CI] = -1.33 to -0.66), 12 hours (SMD = -0.80; 95% CI = -1.05 to -0.56), and 24 hours (SMD = -0.72; 95% CI = -1.02 to -0.43). The results of the sensitivity analysis confirmed the findings of the primary analysis. Based on these results, it can be concluded that premedication is effective in reducing postoperative pain in teeth with irreversible pulpitis. However, additional quality studies are required for further validation.

Zinc oxide nanopillars as an electrocatalyst for direct redox sensing of cadmium

Gaurav Bhanjana,Neeraj Dilbaghi,Nitin Kumar Singhal,김기현,Sandeep Kumar 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.53 No.-

In this paper, we report an ultrasensitive and selective technique for direct electrochemical sensing of cadmium (Cd) by zinc oxide nanopillars (ZONPs) synthesized using a facile chemical method. The synthesized ZONPs have been characterized in terms of their topological, morphological, elemental, structural, and optical properties using various microscopic and spectroscopic techniques. A gold electrode was modified with the as-synthesized ZnO nanostructures and utilized for direct redox sensing of Cd using cyclic voltammetry (CV) and chronoamperometric techniques. This fabricated sensor demonstrated excellent sensitivity and selectivity for direct redox sensing of Cd in real and laboratory samples. Using chronoamperometry, the developed sensor demonstrated ultra-sensitivity (10 mA cm2 ppb1) with a detection limit of 4 ppb (p-value < 0.0001, R-value > 0.99) in a linear range of 5–50 ppb. The enhanced reproducibility of the sensor in the presence of common interfering ions offers the potential for use in diagnostic applications involving food adulteration and in clinical healthcare.

Molybdenum-Based Electrocatalysts for Direct Alcohol Fuel Cells: A Critical Review

Gaurav Kumar Yogesh,Rungsima Yeetsorn,Waritnan Wanchan,Michael Fowler,Kamlesh Yadav,Pankaj Koinkar The Korean Electrochemical Society 2024 Journal of electrochemical science and technology Vol.15 No.1

Direct alcohol fuel cells (DAFCs) have gained much attention as promising energy conversion devices due to their ability to utilize alcohol as a fuel source. In this regard, Molybdenum-based electrocatalysts (Mo-ECs) have emerged as a substitution for expensive Pt and Ru-based co-catalyst electrode materials in DAFCs, owing to their unique electrochemical properties useful for alcohol oxidation. The catalytic activity of Mo-ECs displays an increase in alcohol oxidation current density by several folds to 1000-2000 mA mg_Pt^-1, compared to commercial Pt and PtRu catalysts of 10-100 mA mg_Pt^-1. In addition, the methanol oxidation peak and onset potential have been significantly reduced by 100-200 mV and 0.5-0.6 V, respectively. The performance of Mo-ECs in both acidic and alkaline media has shown the potential to significantly reduce the Pt loading. This review aims to provide a comprehensive overview of the bifunctional mechanism involved in the oxidation of alcohols and factors affecting the electrocatalytic oxidation of alcohol, such as synthesis method, structural properties, and catalytic support materials. Furthermore, the challenges and prospects of Mo-ECs for DAFCs anode materials are discussed. This in-depth review serves as valuable insight toward enhancing the performance and efficiency of DAFC by employing Mo-ECs.

A Voltage and Frequency Controller for Stand Alone Pico Hydro Generation

Gaurav Kumar Kasal,Bhim Singh 전력전자학회 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.2

This paper deals with a voltage and frequency (VF) controller for an isolated power generation system based on an asynchronous generator (AG) driven by a pico hydro turbine. The proposed controller is a combination of a static compensator (STATCOM) and an electronic load controller (ELC) for decoupled control of the reactive and active powers of the AG system to control the voltage and frequency respectively. The proposed generating system along with its VF controller is modeled in MATLAB using SIMULINK and PSB (Power System Block Sets) toolboxes. The performance of the controller is verified for the proposed system and feeding various types of consumer load such as linear/non-linear, balanced/unbalanced and dynamic loads.

Using multi-source data and decision tree classification in mapping vegetation diversity

Gaurav Shukla,Rahul Dev Garg,Pradeep Kumar,Hari Shanker Srivastava,Pradeep Kumar Garg 대한공간정보학회 2018 Spatial Information Research Vol.26 No.5

This study acknowledges the problem of land cover demarcation in diverse vegetation condition. The Normalized Difference Vegetation Index is used for the preparation of base map. Further identification of mix and incorrect classes was done using ground truth. Radar data in combination with optical indices are used. In different NDVI classes, rRV with additional criteria on Normalized Difference Water Index successfully demarcated waterlogged area, polarization ratio rRV/rRH and backscattering coefficient rRH are found suitable to separate bare land from dry grass land, sparse and dense scrub could be separated by - (rRV ? rRH)/2 and NDVI is efficient to identify dense vegetation. The study area is taken as Keoladeo National Park in Bharatpur, India. Statistical similarity between ground truth and classified class has been assessed using Jaccard coefficient (JC), Jaccard distance (JD), Dice coefficient (DC) and F-score. High similarity values of JC, JD, DC and F-score are achieved for all land cover types except bare land. Although, dry grassland showed low value of F-score; the reason could be low precision of class. The overall accuracy (87.17%), producer’s accuracy (86.39%), user’s accuracy (85.81%) and Kappa Coefficient (0.84) are also utilized to analyze performance of classifier.

A Voltage and Frequency Controller for Stand Alone Pico Hydro Generation

Kasal, Gaurav Kumar,Singh, Bhim The Korean Institute of Power Electronics 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.2

This paper deals with a voltage and frequency (VF) controller for an isolated power generation system based on an asynchronous generator (AG) driven by a pico hydro turbine. The proposed controller is a combination of a static compensator (STATCOM) and an electronic load controller (ELC) for decoupled control of the reactive and active powers of the AG system to control the voltage and frequency respectively. The proposed generating system along with its VF controller is modeled in MATLAB using SIMULINK and PSB (Power System Block Sets) toolboxes. The performance of the controller is verified for the proposed system and feeding various types of consumer load such as linear/non-linear, balanced/unbalanced and dynamic loads.