Neutral Point Clamped Transformerless Multilevel Converter for Grid-Connected Photovoltaic System

Transformer-less (TL) inverter topologies have elicited further special treatment in photo-voltaic (PV) power system as they provide high efficiency and low cost. Neutral point clamped (NPC) multilevel-inverter (MLI) topologies-based transformer-less are being immensely used in grid-connected medium-voltage high-power claims. Unfortunately, these topologies such as NPC-MLI, full-bridge inverter with DC bypass (FB-DCBP) suffer from the shoot-through problem on the bridge legs, which affect the reliability of the implementation. Based on the previous above credits, a T type neutral point clamped (TNP) - MLI (TNP-MLI) with Transformer-less topology called TL-TNP-MLI is presented to be an alternate which can be suitable in the grid connected PV power generation systems. The suggested TL-TNP-MLI topologies free from inverter bridge legs shoot-through burden, switching frequency common-mode current (CMC), and leakage current. The control system of the grid interface with hysteresis current control (HCC) strategy is proposed. The effectiveness of the proposed PV connected transformer-less TNP-MLI topology with different grid and PV scenario has been verified through the MATLAB/Simulink simulation model and field-programmable gate area (FPGA) based experimental results for a 1.5 kW system.publishedVersio

Genetic Profile Evaluation of Human Cell Lines Treated with Anastatica hierochuntica Using Forensic DNA Fingerprinting Markers

Cell line authentication using Short Tandem Repeats (STRs) is necessary to ensure the integrity of the cell for its continuous culture and to identify misidentification and cross-contamination issues. This study investigates the changes in the genetic profile of MCF-7 and HepG2 cell lines caused by the methanolic leaf extract of Anastatica hierochuntica (AH) using human identification based STR markers. MCF-7 and HepG2 cell lines were treated with various concentrations of AH extracts for three different periods. The treated and control cells' DNA was extracted using a QIAamp® DNA Micro Kit, quantified using a Quantifiler Duo DNA Quantification Kit, and amplified using an AmpFlSTR Identifiler plus PCR Amplification Kit. The concentrations of the DNA extracted from control and MCF-7 and HepG2 cell lines treated with AH extract at 300 to 2400 µg/ml for 24hr and 150 to 2400 µg/ml for 48 and 72hrs were statistically significant (p<0.05). Microsatellite instability (MSI), loss of heterozygosity (LOH), insertion/deletions changes in the STRs profile were observed in treated cell lines at 1200 and 2400 µg/ml in MCF-7 cells for 48 and 72hrs and HepG2 cells for 24, 48, and 72hrs. We conclude that the highest concentration of AH extracts affected the genotype of the cell lines leading to misidentification. Therefore, cell line authentication by forensic DNA analysis techniques plays a decisive role for cells tested with a high concentration of chemical compounds and gives the forensic investigator an insight into these changes in the STR genotype of a victim/suspect who has been been under long term chemotherapeutic treatment

A multi-perspective dynamic feature concept in adaptive NC machining of complex freeform surfaces

This paper presents a new concept of feature for freeform surface machining that defines the changes in feature status during real manufacturing situations which have not been sufficiently addressed by current international standards and previous research in feature technology. These changes are multi-perspective, including (i) changes in depth-of-cut: the geometry of a feature in the depth-of-cut direction changes during different machining operations such as roughing, semi-finishing and finishing; (ii) changes across the surface: a surface may be divided into different machining regions (effectively sub-features) for the selection of appropriate manufacturing methods for each region such as different cutting tools, parameters, set-ups or machine tools; and (iii) changes in resources or manufacturing capabilities may require the re-planning of depth-of-cuts, division of machining regions and manufacturing operations (machines, tools, set-ups and parameters). Adding the above dynamic information to the part information models in current CAD systems (which only represent the final state of parts) would significantly improve the accuracy, efficiency and timeliness of manufacturing planning and optimisation, especially for the integrated NC machining planning for complex freeform surfaces. A case study in an aircraft manufacturing company will be included in this paper

Simplified equation for Young’s modulus of CNT reinforced concrete

This research investigation focuses on finite element modeling of carbon nanotube (CNT) reinforced concrete matrix for three grades of concrete namely M40, M60 and M120. Representative volume element (RVE) was adopted and one-eighth model depicting the CNT reinforced concrete matrix was simulated using FEA software ANSYS17.2. Adopting random orientation of CNTs, with nine fibre volume fractions from 0.1% to 0.9%, finite element modeling simulations replicated exactly the CNT reinforced concrete matrix. Upon evaluations of the model, the longitudinal and transverse Young’s modulus of elasticity of the CNT reinforced concrete was arrived. The graphical plots between various fibre volume fractions and the concrete grade revealed simplified equation for estimating the young’s modulus. It also exploited the fact that the concrete grade does not have significant impact in CNT reinforced concrete matrix

Microbiologically influenced corrosion in dairy effluent

In the dairy industry mild steel is used as the construction material for the effluent treatment plants, pipelines, reinforcement in concrete structures etc. The steel exposed to the dairy effluent faces corrosion due to the microbes. In the present study the role of microbes in dairy effluent on the corrosion of mild steel has been investigated. Pseudomonas sp., Streptococcus sp., Micrococcus sp., Bacillus sp., Neisseria sp. and Lactobacillus sp. were identified in dairy effluent. Corrosion rate has been estimated by weight loss measurements and polarization technique. The Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometer (XRD) studies were found helpful in investigating the chemical pathway leading to the formation of corrosion products on the mild steel during fermentation. Initiation of pitting corrosion was noticed on steel specimens by scanning electron microscope (SEM). A mechanism has been proposed for microbiologically influenced corrosion in dairy effluent

Gold supported calcium deficient hydroxyapatite for room temperature co oxidation

Gold supported hydroxyapatite (HA) and calcium deficient hydroxyapatite (CDHA) was studied for the room temperature CO oxidation. Nanostructured gold catalyst has been prepared by deposition precipitation method, whereas HA was synthesized by microwave synthesis. Inorder to understand the influence of surface properties of HA, support HA was synthesized with different Ca/P ratios (1.67, 1.62, 1.57, 1.534 and 1.5). The gold supported catalysts were characterized by XRD, BET, ICP-OES and TEM. Typical results indicate that gold supported 1.57 HA shows higher activity compared to other HA catalysts (1.67, 1.62, 1.534 and 1.5) which may be due to the presence of optimum number of acidic and basic site