Study Of Grid Connected Induction Generator for wind Power Applications

Over the past few decades, there has been an increasing use of induction generator particularly in wind power applications. In generator operation, a prime mover (turbine, engine) drives the rotor above the synchronous speed. Stator flux still induces currents in the rotor, but since the opposing rotor flux is now cutting the stator coils, active current is produced in stator coils, and motor now operates as a generator, and sends power back to the electrical grid. Based on the source of reactive power induction generators can be classified into two types namely standalone generator and Grid connected induction generator. In case of standalone IGs the magnetizing flux is established by a capacitor bank connected to the machine and in case of grid connection it draws magnetizing current from the grid. This project explicitly deals with the study of grid connected induction generators where frequency and voltage of the machine will be dictated by the electric grid. Among these types of IGs, Doubly Fed Induction Generator (DFIG) wind turbines are nowadays increasingly used in large wind farms because of their ability to supply power at constant voltage and frequency. Modern control techniques such as Vector control and MFC (magnitude and frequency control) are studied and some of proposed systems are simulated in MATLAB-SIMULINK environment.

Status of vitamin D, lipid profile and carotid artery intima media thickness in patients with chronic kidney disease stage III to V

Background: Chronic Kidney Disease (CKD) is characterized by irreversible sclerosis and loss of nephrons. The renal mass progressively declines over a prolonged period, depending on the underlying etiology. In CKD the most common feature is hypovitaminosis D which alter the vascular smooth muscle cell proliferation and reprogram the osteoblastic changes, finally leading to increase arterial wall thickness.Methods: A cross sectional study carried out over a 2-year period in Department Nephrology and General Medicine OPD, MIMS, Vizianagaram, Andhra Pradesh, India. 120 in which 60 are normal healthy individuals and 60 are CKD patients with stage 3 to 5. In all the participants serum creatinine, blood urea, serum triglycerides serum total cholesterol, HDL cholesterol estimated and serum 25 OH vitamin D are estimated.Results: The diagnostic criteria for CKD like blood urea, serum creatinine and eGFR were significantly higher in CKD when compared to control. In the present study, systolic and diastolic blood pressure was significantly increased in CKD compared with control. The Carotid Intima Media Thickness (CIMT) both left and right side were significant higher in CKD when compared with control. There is a significantly decreased levels of serum vitamin D in CKD (14.53 ng/mL±6.88) when compared with control (28.87 ng/mL±6.28).Conclusions: Present study finding suggested that there is a raised value of CIMT in CKD patients. High triglycerides, cholesterol and decreased HDL and declined vitamin D low hemoglobin, decreased eGFR, increased systolic blood pressure, raised CIMT value were found to be significantly increased in CKD patients

Biomaterials in Endodontics: a review

Biomaterials have evolved over the past three decades and are relatively specialized, highly biocompatible, but low-strength dental materials. Bioactive materials can interact with living tissues or systems. The newly emerging bioactive category of dental materials has expanded clinical uses in restorative dentistry and endodontics. Examples of bioactive materials are  Calcium Silicate containing Mineral Trioxide Aggregate (Portland cement); Calcium Silicate cements lacking aluminium and containing phosphate: Bioagrregate,  iRoot SP and iRoot BP (Endosequence), Calcium Silicate cements containing predominantly Tricalcium Silicate: Bio-active Glass, Calcium Phosphate based materials: Tricalcium Phosphate, Hydroxyapatite, Calcium Phosphate cements and Calcium Aluminate based materials: GIC based luting cements; Bioactive Glass. Other biomimetic materials include Emdogain, Platelet Rich Plasma, Platelet Rich Fibrin, Bone grafts and barrier membranes. Thus, the objective of this review was to compare and review the composition, and properties of these bioactive materials in endodontics

A bibliometric analysis of the 100 most-cited articles in dental materials journals

Background: Bibliometric studies are important as they provide an overview of research and scientific activity in a specific field. But studies of this type to determine the characteristics of the most cited articles in dental materials journals are completely lacking. Aim: To analyze the characteristics of 100 most-cited articles in dental materials journals since its inception through April 2019. Material and methods: Google scholar database was used to retrieve the list of journals titled with the term ‘‘dental materials”. A search was then conducted under "Publication Name" for each of the selected journals, and the articles were grouped by the category "Times Cited". The 100 highly cited papers published in five journals were contemplated in the eventual inquiry. The final collection was subjected to further scrutiny to determine the nature and characteristics of the documented revelations regard to journal name, year of publication, authors and their country, type of article, and area of research. Results: The 100 most-cited articles were published between 1985 and 2016 with maximum publications during 2001-05. The number of citations was ranging from 1926to 304. Only Dental Materials (97), Dental Materials Journal (3), shared the list.  The United States tops the list with 25 articles followed by Germany (12) and Belgium (11). Dental composites and adhesives were the most commonly addressed topics in dental materials journals. Conclusions: This bibliometric analysis connoted the evolving and interesting research trends in dental material science

Comparative evaluation of sealer penetration depth into radicular dentinal tubules using confocal scanning microscope: an in vitro study

Background: Endodontic treatment involves the removal of the vital and necrotic contents of the root canal through chemo-mechanical means followed by obturation of the prepared root canal to prevent the ingress of fluids and avoid bacterial infection or regrowth. Root canal sealers and core filling materials are used together to fill the irregularities in the root. Penetration into the dentinal tubules also results in the inhibition of bacterial regrowth and increases the success of root canal therapy. Aim: This study aimed to evaluate the penetration depth of various sealers into the dentinal tubules using a confocal microscope. Materials and methods: A total of 65 specimens were decoronated to standardize the root length of 13mm. Working length was determined, and Biomechanical preparation for all the samples was done with a rotary ProTaper file till F4. Samples were randomly divided into five groups containing 13 teeth in each group based on the sealer used, namely Group 1: Endomethasone (n=13), Group 2: AH-Plus (n=13), Group 3: Roekoseal (n=13), Group 4: MTA Fillapex (n=13), Group 5: Endosequence BC (n=13). All the sealers were labelled with Rhodamine-B dye, and samples were obturated using cold lateral compaction technique. The specimens were sectioned orthogonally at coronal, middle, and apical thirds. All the samples were examined with a Zeiss Pascal Laser Scanning Microscope to examine the sealer penetration depth into the dentinal tubules. The data were subjected to statistical analysis using one- way Analysis of Variance (ANOVA) and Tukey\u27s Honest Significant Difference (HSD) tests. Results: Endosequence BC showed the highest penetration into dentinal tubules, followed by MTA Fillapex and Roekoseal, AH-Plus, and Endomethasone exhibited the least penetration. Conclusion: Endosequence BC sealer exhibited maximum penetration. All the groups showed maximum penetration at coronal third, followed by the middle and apical third

Therapeutic S100A8/A9 blockade inhibits myocardial and systemic inflammation and mitigates sepsis-induced myocardial dysfunction

Endotoxemia; Inflammation; Mitochondrial functionEndotoxemia; Inflamación; Función mitocondrialEndotoxèmia; Inflamació; Funció mitocondrialBackground and Aims The triggering factors of sepsis-induced myocardial dysfunction (SIMD) are poorly understood and are not addressed by current treatments. S100A8/A9 is a pro-inflammatory alarmin abundantly secreted by activated neutrophils during infection and inflammation. We investigated the efficacy of S100A8/A9 blockade as a potential new treatment in SIMD. Methods The relationship between plasma S100A8/A9 and cardiac dysfunction was assessed in a cohort of 62 patients with severe sepsis admitted to the intensive care unit of Linköping University Hospital, Sweden. We used S100A8/A9 blockade with the small-molecule inhibitor ABR-238901 and S100A9−/− mice for therapeutic and mechanistic studies on endotoxemia-induced cardiac dysfunction in mice. Results In sepsis patients, elevated plasma S100A8/A9 was associated with left-ventricular (LV) systolic dysfunction and increased SOFA score. In wild-type mice, 5 mg/kg of bacterial lipopolysaccharide (LPS) induced rapid plasma S100A8/A9 increase and acute LV dysfunction. Two ABR-238901 doses (30 mg/kg) administered intraperitoneally with a 6 h interval, starting directly after LPS or at a later time-point when LV dysfunction is fully established, efficiently prevented and reversed the phenotype, respectively. In contrast, dexamethasone did not improve cardiac function compared to PBS-treated endotoxemic controls. S100A8/A9 inhibition potently reduced systemic levels of inflammatory mediators, prevented upregulation of inflammatory genes and restored mitochondrial function in the myocardium. The S100A9−/− mice were protected against LPS-induced LV dysfunction to an extent comparable with pharmacologic S100A8/A9 blockade. The ABR-238901 treatment did not induce an additional improvement of LV function in the S100A9−/− mice, confirming target specificity. Conclusion Elevated S100A8/A9 is associated with the development of LV dysfunction in severe sepsis patients and in a mouse model of endotoxemia. Pharmacological blockade of S100A8/A9 with ABR-238901 has potent anti-inflammatory effects, mitigates myocardial dysfunction and might represent a novel therapeutic strategy for patients with severe sepsis.Open access funding provided by Lund University. This study was supported by grants from the Marianne and Marcus Wallenberg Foundation the Swedish Heart and Lung Foundation, the Swedish Research Council, the Bundy Academy foundation at Lund University, Skåne Region Research Funds, Malmö University Hospital Funds, the Crafoord Foundation, the Royal Physiographic Society in Lund, Swedish Research Council, Östergotland Region Research Funds, and the Ministry of Research and Education of Romania (PNRR-C9/I8-CF148)

Optimization of Low-Dose Tomography via Binary Sensing Matrices

X-ray computed tomography (CT) is one of the most widely used imaging modalities for diagnostic tasks in the clinical application. As X-ray dosage given to the patient has potential to induce undesirable clinical consequences, there is a need for reduction in dosage while maintaining good quality in reconstruction. The present work attempts to address low-dose tomography via an optimization method. In particular, we formulate the reconstruction problem in the form of a matrix system involving a binary matrix. We then recover the image deploying the ideas from the emerging field of compressed sensing (CS). Further, we study empirically the radial and angular sampling parameters that result in a binary matrix possessing sparse recovery parameters. The experimental results show that the performance of the proposed binary matrix with reconstruction using TV minimization by Augmented Lagrangian and ALternating direction ALgorithms (TVAL3) gives comparably better results than Wavelet based Orthogonal Matching Pursuit (WOMP) and the Least Squares solution

Reconstruction of sparse-view tomography via preconditioned Radon sensing matrix

Computed Tomography (CT) is one of the significant research areas in the field of medical image analysis. As X-rays used in CT image reconstruction are harmful to the human body, it is necessary to reduce the X-ray dosage while also maintaining good quality of CT images. Since medical images have a natural sparsity, one can directly employ compressive sensing (CS) techniques to reconstruct the CT images. In CS, sensing matrices having low coherence (a measure providing correlation among columns) provide better image reconstruction. However, the sensing matrix constructed through the incomplete angular set of Radon projections typically possesses large coherence. In this paper, we attempt to reduce the coherence of the sensing matrix via a square and invertible preconditioner possessing a small condition number, which is obtained through a convex optimization technique. The stated properties of our preconditioner imply that it can be used effectively even in noisy cases. We demonstrate empirically that the preconditioned sensing matrix yields better signal recovery than the original sensing matrix