Analysis and Implementation of Unipolar PWM Strategies for Three Phase Cascade Multilevel Inverter Fed Induction Motor Drive

This paper presents unipolar pulse width modulation technique with sinusoidal sampling pulse width modulation are analyzed for three-phase five-level, seven-level, nine-level and eleven-level cascaded multi-level inverter. The unipolar PWM method offers a good opportunity for the realization of the Three-phase inverter control, it is better to use the unipolar PWM method with single carrier wave compared to two reference waves. In such case the motor harmonic losses will be considerably lower.The necessary calculations for generation of unipolar pulse width modulation strategies have presented in detail. The unipolar SPWM voltage switching scheme is selected in this paper because this method offers the advantages of effectively doubling the switching frequency of the inverter voltage. The cascaded multi level inverter fed induction motor is simulated and compared the total harmonic distroction for all level (five-level, seven-level, nine-level and elevel-level)of the inverter. Theoretical investigations were confirmed by the digital simulations using MATLAB/SIMULINK software

Investigation of TTMC-SVPWM Strategies for Diode Clamped and Cascaded H-bridge Multi-level Inverter Fed Induction Motor Drive

This paper presents a concept of two types multilevel inverters such as diode clamped and cascaded H-bridge for harmonic reduction on high power applications. Normally, multilevel inverters can be used to reduce the harmonic problems in electrical distribution systems. This paer focused on the performance and analysis of a three phase seven level inverter including diode clamped and cascaded H-bridge based on new tripizodal triangular space vector PWM technique approaches. TTMC based modified Space vector Pulse width modulation technique so called tripizodal triangular Space vector Pulse width modulation (TTMC-SVPWM) technique. In this paper the reference sine wave generated as in case of conventional off set injected SVPWM technique. It is observed that the TTMC-Space vector pulse width modulation ensures excellent, close to optimized pulse distribution results and THD is compared to seven level, diode clamped and cascaded multi level inverters. Theoretical investigations were confirmed by the digital simulations using MATLAB/SIMULINK software

Nephrolithiasis – Most Debilitating Renal Disorder

Both metabolic and environmental risk factors are involved in the pathogenetic mechanisms of kidney stone formation. Major advances have been made in the concept of the pathogenesis, diagnosis, and treatment of kidney stone disease over the last decade. It remains a major health burden worldwide. It is considered a systemic disorder associated with chronic kidney disease, bone loss and fractures, increased risk of coronary artery disease, hypertension, type 2 diabetes mellitus, and the metabolic syndrome. Many therapeutic interventions which can effectively target the stones are available but these are associated with untoward effects. In the pursuit of finding better alternatives, large number of plants was screened for their antiurolithiatic activity. They were found to possess potent activity with minimal/no side effects. Development of new therapeutic agents is possible by understanding the link between nephrolithiasis and these systemic disorders

Nephrolithiasis – Most Debilitating Renal Disorder

Both metabolic and environmental risk factors are involved in the pathogenetic mechanisms of kidney stone formation. Major advances have been made in the concept of the pathogenesis, diagnosis, and treatment of kidney stone disease over the last decade. It remains a major health burden worldwide. It is considered a systemic disorder associated with chronic kidney disease, bone loss and fractures, increased risk of coronary artery disease, hypertension, type 2 diabetes mellitus, and the metabolic syndrome. Many therapeutic interventions which can effectively target the stones are available but these are associated with untoward effects. In the pursuit of finding better alternatives, large number of plants was screened for their antiurolithiatic activity. They were found to possess potent activity with minimal/no side effects. Development of new therapeutic agents is possible by understanding the link between nephrolithiasis and these systemic disorders

Co-existence of hypertensive urgency and hemolysis elevated liver enzymes and low platelets syndrome in a parturient with myasthenia gravis: a therapeutic challenge

Hemolysis elevated liver enzymes and low platelets (HELLP syndrome) is an obstetric emergency developed in the settings of hypertensive disorder of pregnancy and it is associated with a heightened risk of adverse fetomaternal outcomes. Obstetric and anaesthetic management is indeed challenging in HELLP syndrome. The presence of myasthenia gravis further complicates the managements issues in these women. Here, in this report, we describe a 35 years G2P1L1 known case of myasthenia gravis, who presented in emergency with uncontrolled hypertension, imminent eclampsia and HELLP syndrome at 29+1 weeks of gestation. Antihypertensive medication included hydralazine, alpha methyldopa, infusions of labetolol and nitroglycerine. She underwent successful vaginal delivery using fentanyl as labour analgesia. Prompt decision making using multidisciplinary team appeared vital in controlling the hypertension adequately and quickly without aggravating myasthenic crisis

Effect of the Pulsed Electromagnetic Field (PEMF) on Dental Implants Stability: A Randomized Controlled Clinical Trial

A pulsed electromagnetic field (PEMF) has been shown to contribute to heightening bone regeneration in a range of clinical areas, including dentistry. Due to the scarcity of studies using PEMF in oral implantology, the present experiment scrutinized the effect of PEMF can lead to improving the stability of the implant. A total of 19 subjects (40 implants in total) were selected to participate in the current study and were randomly allocated to either the PEMF group or control group. Subjects in the PEMF group received an activated miniaturized electromagnetic device (MED) while the control group received a sham healing cup. Implants stability was assessed by resonance frequency analyses (RFA) via implant stability quotient (ISQ) calculations. RFA were recorded as following: immediately after procedure, and then 2, 4, 6, 8 and 12 weeks later. Radiographic analysis was performed at baseline, 6 and 12 weeks after implant placement. Proinflammatory cytokines were evaluated in peri-implant crevicular fluid (PICF). The PEMF group presented higher ISQ mean values when compared to the control group. The primary stability time frame (the first 2 weeks) MED group depicted an increase in stability of 6.8%, compared to a decrease of 7.6% in the control group related to the baseline. An overall stability increase of 13% was found in MED treated group (p = 0.02), in contrast, the overall stability in the control group decreased by 2% (p = 0.008). TNF-α concentration during first 4 weeks was lower in the MED treated group. The data strongly suggests that MED generated continuing a PEMF may be considered as a new way to stimulate the stability of the implants at the early healing period

Performance Analysis of Modified SVPWM Strategies for Three Phase Cascaded Multi-level Inverter fed Induction Motor Drive

This paper presents new modified space vector pulse width modulation techniques (Phase disposition-Space vector pulse width modulation, Alternative Phase Opposition disposition- Space vector pulse width modulation and Phase Opposition disposition-Space vector pulse width modulation) are analyzed for three-phase cascaded multi-level inverter fed induction motor from the point of view of the Phase voltages, line voltage, stator current,speed,torque and Total harmonic distortion.in the proposed modified technique the reference signals are generated by adding offset voltage to the reference phase voltages.This modified SVPWM technique does not involve region indentification,sector identification for switching vector determination as are required in the conventional multi level SVPWM technique,it is also reduces the computation time compared to the conventional space vector PWM technique.The necessary calculations for generation of new modified SVPWM for the modulation strategies have presented in detail.  It is observed that the modified SVPWM modulation ensures excellent, close to optimized pulse distribution results and THD is compared to for five-level, seven-level, nine-level and eleven-level Cascaded H-Bride Multi-level Inverter fed to Induction motor. Theoretical investigations were confirmed by the digital simulations using MATLAB/SIMULINK software

Qualitative analysis of biodiesel produced by alkali catalyzed transesterification of waste cooking oil using different alcohols

The present study evaluates the nature of fatty acid methyl esters (FAMEs) formed through alkali-catalyzed transesterification of waste cooking oil (WCO) using methanol, ethanol as well as in combination, where the sequential addition of ethanol followed by methanol is done keeping the molar ratio of alcohol to oil constant (5:1), with sodium hydroxide as catalyst. A substantial reduction in reaction time from 8 h to 20 min is seen in the latter case. Further, the gas chromatography/mass spectrometry (GC-MS) analysis of the transesterified oil show a significant presence of FAMEs. Transesterified oil obtained from a combination of both the solvents show substantial quantities of unsaturated FAMEs [linoleic acids (41.89%), palmitelaidic acid (7.97%)], saturated FAMEs [stearic acids (4.62%), arachidic acids (2.54%)]and minor fraction of other acids. Hence, the utilization of WCO with the use of combined solvent system for transesterification, appear to have a great potential for replacing the conventional substrates that are being used for biodiesel production without much compromising on engine modifications