Practical considerations regarding power factor for nonlinear loads

This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. Copyright @ 2004 IEEEThe choice of LC compensator may be constrained by the availability of manufacturers units. To account for this, the capacitor values are chosen from among standard values and for each value the transmission losses is minimized, or power factor is maximized, or transmission efficiency is maximized. The global minimum or maximum is obtained by scanning all local minims or maxims. The performance of the obtained compensator is discussed by means of numerical examples

LC compensators for power factor correction of nonlinear loads

This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. Copyright @ 2004 IEEEA method is presented for finding the optimum fixed LC compensator for power factor correction of nonlinear loads where both source voltage and load current harmonics are present. The LC combination is selected because pure capacitive capacitors alone would not sufficiently correct the power factor. Optimization minimizes the transmission loss, maximizes the power factor, and maximizes the efficiency. The performance of the obtained compensator is discussed by means of numerical examples

Endoscopic Approach for Tissue Expansion for Different Cosmetic Lesions in Pediatric Age

Background/Purpose: The use of tissue expanders in plastic and reconstruction surgery is now well established for large defects in adults & children. Tissue expansion is one of the reconstructive surgeon's alternatives in providing optimal tissue replacement when skin shortage is a major problem. Predesigned plan about the criteria of tissue expansion should be implied before embarking on removal of a lesion. Endoscopic placement of tissue expanders has the benefit of reducing operative time, major complication rate, time to full expansion and length of hospital stay compared to the open technique for tissue expander placement. Materials & Methods: The study was carried on 15 cases for which 22 expanders were inserted .All cases were in the pediatric age (6-15 years) .Nine cases had melanocytic pigmented naevi, four cases had post-burn scars, one had pigmented lymphangiomatous lesion & the last case had post grafting scarring .Eight patients needed single insertion of the expander followed by definitive reconstruction (2 months later), 4 cases needed multiple expanders on the same session & 3cases needed sequential expansion. The process of expander placement was done through a remote incision using endoscopic approach, after the required inflation (usually 2 months) reconstructive surgery was carried on for flap designing. Results: Twenty two expanders were inserted in 15 cases .operating time ranged from 50-70 min. (mean= 1 hour) in early cases .Later on the time was shortened to a mean of 40 ± 5 min. The mean duration for completion of expansion to the required dimensions needed for the flap was 2 months ( + 2 weeks ) . Complication rate was 18%. They occurred in 4 out of 22 expanders (hematoma ,wound dehiscence and seroma around 2 expanders). Conclusion: Tissue expansion in the pediatric population has its implication in different plastic problems. Endoscopic assisted expansion is a new trend in expander placement that has its role in decreasing complications related to insertion of expanders. Index Word: Tissue expansion- Endoscopic- Pediatric

Progranulin and TMEM106B: when two become wan

Mutations in GRN, which encodes progranulin, are a common cause of familial frontotemporal dementia (FTD). FTD is a devastating disease characterised by neuronal loss in the frontal and temporal lobes that leads to changes in personality, behaviour and language. There are no effective treatments for this complex condition. TMEM106B is a well‐recognised risk factor for FTD caused by GRN mutation. While the specific relationship between progranulin and TMEM106B is unclear, it is well established that they are both required for correct lysosome function and trafficking. Elegant experiments have suggested that increased risk for FTD is due to elevated levels of TMEM106B (Nicholson et al, 2013; Gallagher et al, 2017). Therefore, recent work has explored the therapeutic potential of reducing TMEM106B levels, with initial results looking encouraging, as crossing a Grn‐deficient mouse to a Tmem106b knockout showed a rescue in FTD‐related behavioural defects and specific aspects of lysosome dysfunction (Klein et al, 2017). However, three independent studies in this issue report that completely removing Tmem106b from Grn knockout mice leads to clear exacerbation of phenotypes, causing severe motor deficits, neurodegeneration and enhanced lysosome abnormalities and gliosis. Remarkably, the double knockout mice also develop TDP‐43 pathology—a hallmark of FTD patients with GRN mutations that have not been consistently observed in either of the single knockouts. These concurrent publications that all reach the same surprising but definitive conclusion are a cautionary tale in the control of TMEM106B levels as a potential therapeutic for FTD. They also re‐ignite the debate as to whether loss or gain of TMEM106B function is critical for altering FTD risk

The progression of chronic renal failure: An unmet challenge

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In vitro antibacterial activity of Parkia biglobosa (Jacq.) root bark extract against some microorganisms associated with urinary tract infections

The medicinal plant Parkia biglobosa (Jacq.) was screened for the phytochemical components and antibacterial activity against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa which are associated with urinary tract infections. Aqueous solutions are more potent than methanolic solutions and activity is concentration dependent. P. aeruginosa is least susceptible than the other organisms

Experimental and numerical investigations of flow through free double baffled gates

Studying the flow patterns and behaviour of double baffled gates under different flow heads is important to improve their performance, which could help in widening the range of their application. In the present study, physical and numerical investigations were conducted on the double baffled gate. A 3D Acoustic Doppler Velocity Meter (ADV) was used for laboratory measurements of the instantaneous velocity fields in the physical gate model. In parallel with this, the CFD Fluent package was adopted to carry out a sensitivity analysis for a matrix of geometric parameters of the double baffled gate. The outcomes of the laboratory and CFD numerical investigations were incorporated in a spreadsheet with the purpose of informing the design of double baffled gates under conditions of non-submergence

Ultrasound Evaluation of the Uterine Scar Thickness after Single Versus Double Layer Closure of Transverse Lower Segment Cesarean Section

Background: The degree of the lower uterine segment (LUS) thinning and the risk of uterine scar defect have been studied. However, the relationship between the methods of closure and the degree of thinning needs further elucidation. Aim: The aim of this study was to determine whether a LUS transverse cesarean section (CS) closure method in one or two layers affects subsequent scar thickness.Subjects and Methods: In this prospective study, 150 women were enrolled and randomly assigned to one‑ or two‑layer closure of the LUS incision. Patients were divided into two groups. Each group included 75 patients, of primigravidae with gestational age from 38 weeks to 40 weeks one group had a single layer closure and the other had a double layer closure.Results: We found an increase in the thickness of LUS‑CS scar in cases with double layer closure of the incision than a single layer closure as depicted by ultrasonography after 2 days and 2 weeks post‑operative.Conclusion: These findings suggest that the number of closing layers of CS directly affect the thickness of the scar. Keywords: Cesarean section, one layer, scar thickness, two layer