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Abstract Nowadays, transformer‐less Photovoltaic‐based grid‐connected inverters are more popular in renewable energy application due to their reduced size, cost, and high efficiency. However, the absence of galvanic isolation leads to the flow of leakage current in such system hindering personal safety, and deteriorating power quality. Therefore, this paper presents a five‐level transformer‐less inverter topology for PV applications with less component count and reduced complexity. The proposed inverter topology completely eliminates the common mode leakage current. Besides, the proposed topology has an inherent capability to boost the voltage without using any magnetic component or boosting circuit, and is based on the principle of switched/auxiliary capacitor. The proposed topology do not have any limitation of modulation index since the auxiliary capacitors are naturally balanced, hence less complex or no dedicated control scheme is required for balancing/regulating the auxiliary capacitor voltages. In order to verify the performance of the proposed inverter topology, a laboratory prototype is developed which confirms the operation, and feasibility of the proposed inverter. Results depicting the output voltage, load current, and voltage across the auxiliary capacitor are presented for various operating conditions. Further, simulation results depicting the leakage current in the proposed, H5, and H6 topologies are included. Finally, a quantitative comparison study is done, highlighting the benefits of the proposed inverter topology regarding boosted voltage, elimination of leakage current, and reduced component count.

Abstract This paper examines a multilevel transformer‐less grid‐tied inverter topology is proposed for PV applications. Nowadays, transformer‐less inverters are more desirous due to their small filter size, cheaper and higher efficiency. However, the removal of transformer results in the existence of leakage current due to absence of galvanic isolation. The flow of leakage current is the cause of personal safety and deteriorating power quality. A transformer‐less inverter topology is proposed which is able to solve the leakage current issue. Besides, it has the ability to generate the boosted voltage without the need of magnetic component or boosting circuit. It works on the principle of flying/switched capacitor which are able to naturally balance the voltage. Hence, it does not have the limitation of modulation index and no need of complex control scheme to balance or regulate the voltage across an auxiliary capacitor. The performance of the proposed topology is verified by implementing a laboratory prototype which validates the operation and performance of the proposed topology. Results depicting the output voltage, load current and voltage across the auxiliary capacitor are presented for various operating conditions. Moreover, a comprehensive comparison is done, in terms of component count, level and boosting ability of output voltage with leakage current condition.

Background and Aims: Popliteal-Sciatic nerve block under Ultrasound Guidance (USG) using a local anesthetic agent like Ropivacaine is an established technique for providing analgesia and muscle relaxation for lower limb surgeries with minimal untoward events. Establishing the minimal volume of 0.2% ropivacaine required to provide intraoperative and postoperative analgesia will further reduce the drug requirements and adverse effects toward the patient. Material and Methods: This randomized prospective observational blinded study was done in a tertiary care referral hospital in South India over 9 months from August 2017 till April 2018. The block was performed on all recruited patients under ultrasound guidance with a starting volume of 16 ml 0.2% ropivacaine. Duration of time for loss of pin-prick sensation around the sole of the foot (tibial nerve) and the lateral malleolus (common peroneal nerve) was noted. If successful, the volume of the drug for subsequent patients was randomized by lottery method to either be kept the same or reduced. If the block failed, the subsequent patient recruited would have an increased volume of drug injected. Results: By Probit regression analysis using the biased coin up-and-down method we found that 9.3 ml (MEAV90) of 0.2% ropivacaine was sufficient for providing adequate analgesia. Factors such as patient age or weight had no role in efficacy of the block. There were no adverse effects such as allergy to the drug or systemic toxicity noted in the studied patients. Conclusion: 9.3 ml of 0.2% ropivacaine is sufficient to provide analgesia (assessed by pin-prick) in 90% of patients undergoing popliteal-sciatic block for lower limb surgeries.

In recent years, nanotechnological research has introduced hybrid nanofluids, which are advanced fluids with augmented thermal properties that give better results than regular nanofluids. The thermal transfer characteristics of the Falkner-Skan flow of MgO-MoS2/Engine oil hybrid nanofluid induced by a wedge surface with thermophoresis and Brownian motion are numerically investigated. The main objective of this research is to examine the augmented thermal transport behavior of Casson and Carreau hybrid nanofluids. The equations that arise are solved by adopting the bvp5c scheme in MATLAB software. Plots and numerical values illustrate the stimulus of various pertinent parameters on the flow-determining factors such as velocity, thermal and concentration fields, wall friction, energy, and mass transports. The rate of energy transport in the Carreau hybrid nanofluid is significantly larger than that of the Casson hybrid nanofluid. The implication of 5% volume of MgO-MoS2 nanoparticles enhances the rate of thermal transport by 53% in the Carreau fluid and 47% in the Casson fluid, respectively. This research holds potential for applications in geothermal energy systems. [ABSTRACT FROM AUTHOR]

AbstractA numerical investigation is performed to scrutinize the enhanced thermal transmission of Carreau nanoliquid above an incessantly moving thin needle in the occurrence of nonuniform heat rise/fall effects. The arising system of nonlinear coupled equations is exercised numerically by employing a suitable numerical scheme, i.e. bvp5c Matlab solver. The prime motive of this research is to determine the effectual thermal conductivity of the nanoliquid by using Maxwell/Xue models to achieve enhanced energy transmission. The stimulus of pertinent constraints upon the flow factors, viz. velocity and thermal gradients, are illustrated through plots. Also, the wall friction and energy transmission rate are bestowed via plots and tabular values. The outcomes reveal that the Xue nanomodel augments the thermal transmission rate of the nanofluid to a greater extent than the Maxwell nanomodel. This research holds potential for applications in geothermal power production. [ABSTRACT FROM AUTHOR]

This article investigates the heat transmission rate in hybrid and tri-hybrid particles that emerged in Oldroyed-B blood flow flowing through wedge shape arteries. The rate type Oldroyd-B flow model is considered to examine the behavior of relaxation and retardation times. The transmuted nondimensional conditions and boundary restrictions are solved using the bvp5c technique. It is observed that the heat transmission rate is high for the tri-hybrid (GO-Al2O3-TiO2) blood flow combination compared to the hybrid (Al2O3-TiO2) blood combination. This study can deliver a vibrant opinion concerning heat transmission behavior and the blood flow nature in a wedge shape artery. [ABSTRACT FROM AUTHOR]

Solar energy is a natural renewable energy source. The sunlight that spreads the earth's atmosphere is sufficient to power all of our essentials. The real-world usage of solar energy is critical to fulfilling current and future needs. This article focuses on the vital use of solar energy by utilizing the nanoaggregation concept. A suitable mathematical model is established by considering the flow slip, hydrodynamics, Ohmic, and radiative heats. The modeled problem was resolved using R-K-based shooting process. Simultaneous outcomes are obtained for the aggregation and nonaggregation cases. This study is a practical application of enhanced heat transport in Parabolic Trough Solar Collector (PTSC). It is found that nanoparticle aggregation aids in enlarging the thermal conduction rate of PTSC. This helps with the practical usage of solar energy. [ABSTRACT FROM AUTHOR]

This paper examines the thermal transfer attributes of ZnO-H2O Walter's-B nanoliquid flow alongside an upright cone in the bearing of slip mechanism, radiative heat flux, and non-uniform heat source. We adopted suitable similarities to convert the nonlinear PDEs into ODEs and solved the transformed governing system by employing the bvp5c solver package in Matlab software. The prime novelty of this research is to compute the effective thermal diffusivity of the nanoliquid via the Maxwell and Xue nanomodels. Further, simultaneous results are deliberated for Maxwell and Xue cases via pictorial outcomes under various controlling limitations, such as velocity slip, radiative heat flux, buoyancy, viscoelastic, and volume fraction of nanomaterial. The thermal transmission rate of nanoliquid reported by the Xue nanomodel is higher than the Maxwell nanomodel. Therefore, the Xue nanomodel effectively works to enhance the thermal conductivity of the liquids with viscoelastic nature. Further, this study is helpful in industrial processing, where control over heat transport is required. [ABSTRACT FROM AUTHOR]