73 research outputs found

    Solar photovoltaic array fed brushless DC motor drive using sensorless technique for reducing vibration with Enhanced DC-DC converter

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    The proposed research work involves, solar photovoltaic array fed brushless DC motor drive using sensorless technique for reducing vibration with Enhanced DC-DC converter. The purpose of this research is to reduce the vibration in the motor drive and to improve the efficiency of the enhanced converter. The designed model consists of Buck and Boost converter, DC-link unit, state-of-the-art back-EMF sensing methods like terminal voltage, terminal current sensing and also includes third choral voltage amalgamation, back-emf integration and PWM strategies. In addition, reduced number of switches in the proposed research makes the scheme more outlay efficient and the motor speed is synchronized by PI controller. For sensing the vibration during rotation and shock in the brushless DC drive an accelerometer which is an electromechanical device are used, it measures acceleration forces associated to the freefall cause, path of the acceleration is a vector product. The current technique based on evaluation of various parameters are clearly modeled and experimented. A MATLAB platform and a hardware prototype of multioutput buck-boost converter are clearly examined for various effective environment in the proposed research

    PSO based optimized PI controller design for hybrid active power filter

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    This research study presents the design and simulation of a hybrid active power filter (HAPF) for reducing harmonics. The reference currents have been determined using the synchronous reference frame technique. To achieve its goals, the proposed HAPF employs AI algorithm known as particle swarm optimization (PSO) to fine-tune the proportional-integral PI controller's parameters. With the help of PI-PSO controller the DC link voltage is regulated in the HAPF-inverter. A non-linear current control strategy based on hysteresis employed here to construct the pulse gate by comparing the retrieved reference and real currents necessitated by the HAPF. Simulations were carried out in MATLAB and shown that the proposed method is extremely adaptable and efficient in reducing harmonic currents caused by non-linear loads

    A novel SVPWM for 3-phase to 5-phase conversion using matrix converter

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    A novel matrix converter has been developed for 3-phase to 5-phase conversion using a novel space vector pulse width modulation. The matrix converter organized to generate 5-phase AC output voltage from 3-phase input voltage with help of SVPWM method; bidirectional power switches placed in matrix converter controlled by appropriate switching pulse. Space vector pulse width modulation (SVPWM) provides better utilization of applied input voltage, improved output voltage, reduced total harmonic distortion. The bidirectional switch used by the matrix converter decreases stress on the power switch and the influence of harmonic fluctuation in AC output voltage. When compared to traditional approaches, the suggested system offers improved output voltage and current control. Using MATLAB/Simulink and FPGA-cyclone controller, respectively, modelling and experimental results have been given to validate the proposed methodology

    Jellyfish search optimizer algorithm based multipledistributed generation placements

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    The efficient and economical operation of a distribution power network (DPN) has been essential in recent times, considering the energy crisis and shortage of fossil fuels. A DPN is known to be efficient and economical if power losses are minimal, the voltage drop along the lines is less, and stability is maintained during different operating conditions. However, due to the crisis for primary fuel, all DPNs including radial power distribution networks (RPDN) are operated at threshold level. This has led to higher power losses, more voltage drops, and stability issues in RDPN. Hence, to reduce the power losses and voltage deviation and improve the stability of the power system network, distributed generation (DG) units are optimally allocated into radial DPN. In this study, an optimization technique using Jellyfish search optimizer (JSO) algorithm is proposed to optimize multiple DGs into RDPN to minimize a multi-objective function corresponds to real power loss (RPL) minimization, voltage stability (VS) enhancement, and total operating cost (TOC) minimization. The performance of the proposed technique is evaluated for multiple type I and type III DGs placement on an IEEE standard 33-bus RDPN. Besides, the effectiveness of the proposed technique is investigated considering a nominal and peak power demand. The efficacy of the research outcome of the suggested JSO approach has been compared with the outcome of other optimization algorithms presented in the literature. The comparison exemplifies that JSO gives more promising outcomes than other algorithms by delivering the least real power losses and better voltage profile enhancement at minimum operating cost

    Differential expression of HIV target cells CCR5 and α4β7 in tissue resident memory CD4 T cells in endocervix during the menstrual cycle of HIV seronegative women

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    BackgroundOvarian hormones are known to modulate the immune system in the female genital tract (FGT). We sought to define the impact of the menstrual cycle on the mucosal HIV target cell levels, and tissue-resident CD4 T cells.Materials and methodsHere, we characterized the distribution, phenotype, and function of CD4 T cells with special emphasis on HIV target cells (CCR5+ and α4β7+) as well as tissue-resident memory (TRM; CD69+ and CD103+) CD4 T cells in FGT of cycling women. Peripheral blood and Endocervical cells (EC-collected from cytobrush) were collected from 105 healthy women and performed multicolor flow cytometry to characterize the various subsets of CD4 T cells. Cervicovaginal lavage (CVL) were collected for cytokine analysis and plasma were collected for hormonal analysis. All parameters were compared between follicular and luteal phase of menstrual cycle.ResultsOur findings revealed no significant difference in the blood CD4 T cell subsets between the follicular and luteal phase. However, in EC, the proportion of several cell types was higher in the follicular phase compared to the luteal phase of menstrual cycle, including CCR5+α4β7-cells (p=0.01), CD69+CD103+ TRM (p=0.02), CCR5+CD69+CD103+ TRM (p=0.001) and FoxP3+ CD4 T cells (p=0.0005). In contrast, α4β7+ CCR5- cells were higher in the luteal phase (p=0.0004) compared to the follicular phase. In addition, we also found that hormonal levels (P4/E2 ratio) and cytokines (IL-5 and IL-6) were correlated with CCR5+ CD4 T cells subsets during the follicular phase of the menstrual cycleConclusionOverall, these findings suggest the difference in the expression of CCR5 and α4β7 in TRM CD4 T cell subsets in endocervix of HIV seronegative women between the follicular and luteal phase. Increase in the CCR5+ expression on TRM subsets could increase susceptibility to HIV infection during follicular phase of the menstrual cycle

    Improved Cardiac Glucose Uptake: A Potential Mechanism for Estrogens to Prevent the Development of Cardiac Hypertrophy

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    The incidence of cardiovascular diseases including cardiac hypertrophy and failure in pre-menopausal women is lower compared to age-matched men but the risk of heart disease increases substantially after the onset of menopause. It has been postulated that female sex hormones play an important role in cardiovascular health in pre-menopausal women. In animal studies including spontaneously hypertensive (SHR) rats, the development of cardiac hypertrophy is attenuated by 17β-estradiol treatment. Cardiac energy metabolism is crucial for normal function of the heart. In cardiac hypertrophy and heart failure, the myocardium undergoes a metabolic shift from fatty acid as primary cardiac energy source to glucose, which re-introduces the fetal type of metabolism that representing the glucose as a major source of energy. Many studies have reported that the disruption of the balance between glucose and fatty acid metabolism plays an important role in cardiac pathologies including hypertrophy, heart failure, diabetes, dilative cardiomyopathy and myocardial infarction. Glucose enters cardiomyocytes via GLUT1 and GLUT4 glucose transporters and GLUT4 is the major glucose transporter which is insulin-dependent. Cardiac-selective GLUT4 deficiency leads to cardiac hypertrophy. This shows that the decrease in cardiac glucose uptake may play a direct role in the pathogenesis of cardiac hypertrophy. Estrogens modulate glucose homeostasis in the liver and the skeletal muscle. But it is not known whether estrogens affect also cardiac glucose uptake which could provide another mechanism to explain the prevention of cardiac hypertrophy by female sex hormones. In the present study, SHR Rats were ovariectomized (OVX), not ovariectomized (sham) or ovariectomized and treated with subcutaneous 17β-estradiol. After 6 weeks of treatment, body weight, the serum levels of estrogen, insulin, intra-peritoneal glucose tolerance test (IP-GTT), myocardial glucose uptake by FDG-PET (2-(18F)-fluoro-deoxyglucose (18FDG) and Positron Emission Tomography), cardiac glucose transporter expression and localization and cardiac hexokinase activity were analyzed. As results of this study, PET analysis of female SHR revealed decreased cardiac glucose uptake in OVX animals compared to intact that was normalized by estrogen supplementation. Interestingly, there was no change in global glucose tolerance among the treatment groups. Serum insulin levels and cardiac hexokinase activity were elevated by E2 substitution. The protein content of cardiac glucose transporters GLUT-4 and GLUT-1, and their translocation as determined by fractionation studies and immuno-staining did not show any significant change by ovariectomy and estrogen replacement. Also levels of insulin receptor substrate-1 (IRS-1) and its tyrosine phosphorylation, which is required for activation and translocation of GLUT4, was un-affected in all groups of SHR. Cardiac gene expression analysis in SHR heart showed that ei4Ebp1 and Frap1 genes which are involved in the mTOR signaling pathway, were differentially expressed upon estrogen treatment. These genes are known to be activated in presence of glucose in the heart. As a conclusion of this study, reduced myocardial FDG uptake in ovariectomized spontaneously hypertensive rat is normalized by 17β-estradiol treatment. Increased myocardial hexokinase appears as a potential mechanism to explain increased myocardial glucose uptake by 17β-estradiol. Increased cardiac glucose uptake in response to 17β-estradiol in ovariectomized SHR may provide a novel mechanism to explain the reduction of cardiac hypertrophy in E2 treated SHR. Therefore, 17β-estradiol improves cardiac glucose utilization in ovariectomized SHR which may give rise to possible mechanism for its protective effects against cardiac hypertrophy.Erkrankungen des kardiovaskulären Systems, wie beispielsweise Herzhypertrophie oder Herzinsuffizienz treten bei Frauen vor der Menopause im Vergleich zu gleichaltrigen Männern seltener auf. Das Risiko für eine solche kardiovaskuläre Erkrankung steigt jedoch drastisch mit dem Beginn der Menopause an. Aus diesem Grund wird angenommen, dass weibliche Geschlechtshormone kardioprotektive Wirkungen besitzen. Tierstudien an spontan hypertensiven Ratten (SHR) haben belegt, dass eine Herzhypertrophie durch die Behandlung der Tiere mit 17β-Estradiol abgemildert werden kann. Entscheidend für die Funktion des Myokards ist sein Energiemetabolimus, der sich im Verlauf einer Hypertrophie oder Herzinsuffizienz vom primären Fettsäurestoffwechsel auf Glucosemetabolismus umschaltet. Diese Situation entspricht der des fetalen Herzens. Viele Studien haben belegt, dass eine Störung der Balance zwischen Glucose- und Fettsäurestoffwechsel oftmals ein erstes Anzeichen für einen pathologischen Zustand des Herzens, wie z.B. Hypertrophie, Herzinsuffizienz, Diabetes, dilative Kardiomyopathie und Myokardinfarkt ist. Im gesunden Herzen gelangt Glucose über die zwei Glucosetransporter GLUT1 und GLUT4 in die Zellen des Myokards, wobei der insulinabhängige Glut4-Transporter der Hauptglucosetransporter ist. Eine GLUT4-Defizienz führt daher ebenfalls zu einer Herzhypertrophie was wiederum zeigt, dass eine verminderte Glucoseaufnahme im direkten Zusammenhang mit pathologischen Zuständen des Herzens steht. Bisherige Studien haben gezeigt, dass Östrogen an der Glucosehomöostase in Leber und Skelettmuskeln beteiligt ist. Jedoch ist wenig darüber bekannt, ob Östrogen ebenfalls in die kardiale Glucosehomöostase eingreift und inwiefern die kardioprotektive Wirkung des Östrogens in diesem Zusammenhang steht.In der vorliegenden Arbeit wurden weibliche SH-Ratten ovariektomiert (OVX), nicht ovariektomiert (sham) oder ovariektomiert und zusätzlich subkutan mit 17β-Estradiol behandelt. Nach einer Behandlungszeit von 6 Wochen wurden dann das Körpergewicht, die Serumspiegel von Östrogen, Insulin und IPGTT bestimmt, und die Glucoseaufnahme des Myokards mittels FDG-PET analysiert. Zusätzlich wurden Expression und zelluläre Lokalisation der kardialen Glucosetransporter sowie die kardiale Hexokinaseaktivität untersucht. Es konnte gezeigt werden, dass sich eine verminderte Glucoseaufnahme des Herzens bei ovariektomierten Tieren durch Östrogen-Supplementation normalisieren lässt. Eine Abweichung bezüglich der Glucosetoleranz der einzelnen Gruppen konnte nicht beobachtet werden. Jedoch konnte ein erhöhter Insulinspiegel des Serums und eine erhöhte kardiale Aktivität des Enzyms Hexokinase durch die Behandlung mit Östrogen bei den ovariektomierten Tieren beschrieben werden. Durch Fraktionierungen und immunhistologische Untersuchungen konnte kein signifikanter Unterschied in Bezug auf die Menge sowie die Translokation der Glucosetransporter GLUT1 und GLUT4 im Myokard zwischen den einzelnen Behandlungen der Tiere beschrieben werden. Ferner konnte zwischen den einzelnen Tiergruppen auch kein Unterschied zwischen dem Insulin Rezeptor Substrat-1 (IRS-1) und seiner Tyrosin-phosphorylierten Form festgestellt werden, die für die Aktivierung und Translokation des GLUT4 benötigt werden. Analysen der Genexpression in den Herzen der SH-Ratten konnten allerdings zeigen, dass die Gene ei4Ebp1 und Frap1, die im mTOR Signalweg involviert sind, bei den Östrogen-supplementierten Tieren ein abweichendes Expressionsmuster aufweisen. Über diese Gene ist bekannt, dass sie in der Gegenwart von Glucose im Herzen aktiviert werden und bei der Entstehung einer Herzhypertrophie mitwirken. Basierend auf den PET-Analysen und der Hexokinaseaktivität lässt sich als Resultat dieser Arbeit aussagen, dass Östrogen die kardiale Glucoseaufnahme in SH-Ratten fördert. Diese Ergebnisse könnten einen Hinweis auf einen noch unbekannten Mechanismus geben, um die protektive Wirkung des Östrogens im Hinblick auf die Herzhypertrophie zu erklären. Hinsichtlich der Tatsache, dass keine Veränderungen in der Translokation der GLUT4-Transporter in der Plasmamembran bei den einzelnen Behandlungen der Tiere zu verzeichnen sind, jedoch Veränderungen der Glucoseaufnahme durch die PET-Analysen dargestellt werden konnten, besteht jedoch noch Erklärungsbedarf. Es liegen diverse Studien vor, die diesen Unterschied damit erklären könnten, dass der GLUT4-Transporter in einer inaktiven Form in der Plasmamembran vorliegt bis die Glucoseaufnahme durch den GLUT4-Transporter mittels der Insulin Signaltransduktionskaskade reguliert wird

    Proteomic identification of non-erythrocytic alpha-spectrin-1 down-regulation in the pre-optic area of neonatally estradiol-17β treated female adult rats

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    Abstract It is well established that sexually dimorphic brain regions, which are critical for reproductive physiology and behavior, are organized by steroid hormones during the first 2 weeks after birth in the rodents. In our recent observation, neonatal exposure to estradiol-17β (E2) in the female rat revealed increase in cyclooxygenase 2 (COX-2) level, sexually dimorphic nucleus (SDN)-pre-optic area (POA) size and down-regulation of synaptogenesis related genes in POA in the adult stage. In the present study, using the same animal model, the protein profile of control and neonatally E2-treated POA was compared by 1D-SDS-PAGE, and the protein that shows a change in abundance was identified by LC-MS/MS analysis. Results indicated that there was a single protein band, which was down-regulation in E2-treated POA and it was identified as spectrin alpha chain, non-erythrocytic 1 (SPTAN1). Consistently, the down-regulation of SPTAN1 expression was also confirmed by reverse transcription polymerase chain reaction (RT-PCR) and Western blot analysis. The SPTAN1 was identified as a cytoskeletal protein that is involved in stabilization of the plasma membrane and organizes intracellular organelles, and it has been implicated in cellular functions including DNA repair and cell cycle regulation. The evidence shows that any mutation in spectrins causes impairment of synaptogenesis and other neurological disorders. Also, protein-protein interaction analysis of SPTAN1 revealed a strong association with proteins such as kirrel, actinin, alpha 4 (ACTN4) and vinculin (VCL) which are implicated in sexual behavior, masculinization and defeminization. Our results indicate that SPTAN1 expression in the developing rat brain is sexually dimorphic, and we suggest that this gene may mediate E2-17β-induced masculinization and defeminization, and disrupted reproductive function in the adult stage.</jats:p
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