178 research outputs found

    The most economical power factor correction according to tariff structures in Egypt

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    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 @ 2005 IEEEA method of applying power-factor (PF) correction capacitors is discussed based on net savings maximization according to Egyptian's Tariff. Test results from examples taken from existing publications are presented. The purpose of this application technique is to utilize existing electrical distribution equipment in the installation of very large values of PF correction capacitors. It is concluded that LC compensators can be installed, thus providing maximum benefits from penalty elimination, system losses reduction, release of system transformer capacity, and minimum switching transients. Paybacks of less than one year can be expected

    Power factor and your electrical utility bill in Egypt

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    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 @ 2003 IEEEBeside being a good neighbor and not causing harmonic voltage for others that are connected to your electrical distribution circuit, complying with the legal requirements of IEEE standards 519, and maintaining safe and economical operating environments for electrical equipment within your physical load, there is another very good reason to maintain a good power factor: saving money on your electrical utility bill. Utilities often encourage consumers to maintain a high PF by applying tariff clauses, which penalize consumers for low PF. This letter discusses the topic

    LC compensators for power factor correction of nonlinear loads

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    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

    Practical considerations regarding power factor for nonlinear loads

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    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

    Applications analytiques des films minces de mercure protégés par du fibrinogène pour la détermination du plomb et du cadmium dans des échantillons d’eaux usées et d’eaux de mer

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    Analytical application of fibrinogen-coated mercury film electrodes for the detection of lead and cadmium in water samplesThe aim of this study was the development of sensor based on fibrinogen (Fbg) coated mercury film electrodes at carbon paste electrode in the perspective of in-field stripping analysis of heavy metals in complex matrix. The preparation, optimization and characterization of coatings of Fibrinogen (Fbg) for the modification of thin mercury film electrodes and its application for the detection of trace metals have been described . The modified carbon paste electrode was prepared by a simple adsorption of fibrinogen from an aqueous solution containing an adequate quantity of fibrinogen. The Mercury film was then prepared by electrodeposition through the fibrinogen coating. The experimental parameters such as concentration of fibrinogen, deposition time and deposition potential were investigated. The performance of this electrode is evaluated in a presence of different surfactants such as gelatine, albumin, SDS and Tween 20, while lead and cadmium were employed as test metal ions. Using selected conditions the limits of detection were 5.10-9 mol.L-1 and 2.10-8 mol.L-1 for lead and cadmium, respectively. Since fibrinogen coated mercury film showed the best performance and increased efficiency against surfactants when comparing to the conventional mercury film, it was used for the analysis of trace metals in environmental samples of  waters and industrial effluents

    Molecular genetics of autosomal recessive retinitis pigmentosa

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    Autosomal recessive retinitis pigmentosa (arRP) is one of the commonest forms of monogenic retinal degeneration (RD). To date, 24 loci have been implicated in the pathogenesis of arRP. The genes for five of these loci (RP22, RP25, RP28, RP29 and RP32), still remain to be identified. This thesis mainly focused on the cloning of a major gene (RP25) however identifying novel loci for recessive RP constituted a significant objective. Originally the RP25 locus was mapped to chromosome 6pl2.1-ql5, a region that spans 34 Mb, by our collaborators in Seville in seven Spanish families. Initially, a whole-genome scan in these families was undertaken using GeneChip 10K array. The data obtained confirmed the initial findings of linkage to the RP25 region. To date, 61 out of 111 genes within the interval (-55%) have been excluded as disease causing by direct sequence analysis. A large number of single nucleotide polymorphisms (SNPs), of which a significant percentage was novel were identified. We have also postulated that both RP25 and Leber congenital amaurosis 5 (LCA5), a severe form of RD, could be due to the same genetic defect since they genetically overlap. Therefore, seventeen LCA families were genotyped to identify new LCA5 families that may further refine the RP25 interval by identifying novel crossovers. However, the gene for LCA5 has been recently cloned and sequence analysis of the RP25 families rules out this gene as causative of RP25. To investigate if copy number variations (CNVs) exist within the RP25 interval, a comparative genome hybridisation (CGH) was performed on one of the RP25 families (RP5). A clone from the tiling path, chr6tp-19C7, within 6ql2 was observed to be deleted in all affected members of this family indicating that one of the genes within this interval could be responsible for the RP25 phenotype. A novel approach utilising the 10K GeneChip for identifying the disease locus in three non-consanguineous Chinese families with arRP was implemented. The studied families were probably linked to the RP25 locus proposing that this approach could be a useful tool for genetic mapping in cases of rare and genetically heterogeneous recessive traits. Finally, in parallel, a genomewide linkage search in a consanguineous family with arRP was undertaken. Linkage to a 10-cM interval on chromosome 10q23.1-23.3 was observed where a good candidate gene, protocadherin-21 (PCDH21), is located. A homozygous 1-bp deletion was identified in this family in addition to two other novel mutations in two different patients raising the possibility that PCDH21 is likely to be a novel gene for RP

    Correlation Between Tumor Necrosis Factor Alpha and Proteinuria in Type-2 Diabetic Patients

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    Introduction: Diabetic Nephropathy (DN) is the single most common cause of end stage renal disease (ESRD) in many countries. Inflammation is a potential factor in the development and progression of DN and recent data indicate that diabetes includes an inflammatory component which may contribute to diabetic complications. Methods: This study was conducted at Ain Shams University Hospital on 95 patients with type-2 diabetes mellitus complicated with retinopathy and fifteen age- and sex-matched healthy volunteers. Diabetic patients were divided into 4 groups according to the degree of proteinuria. Serum tumor necrosis factor-α (TNF-α), urine TNF-α and C-reactive protein (CRP) levels were measured in all subjects. Correlations between these inflammatory parameters and degree of proteinuria, duration of diabetes and degree of glycemic control were examined. Results: Levels of the three inflammatory parameters were significantly higher in diabetic patients when compared to control subjects, and they were positively correlated to urinary protein excretion. There was significant positive correlation between serum and urine TNF-α and duration of diabetes, as well as between serum TNF-α and glycemic control. Serum and urine TNF-α remained as independent predictors of urine protein excretion in diabetic patients with overt proteinuria after forward stepwise multiple regression analysis. Conclusion: Serum and urine TNF-α and CRP levels are significantly elevated in this group of diabetic patients, and correlate positively with severity of proteinuria. This suggests a significant role for TNF-α in the pathogenesis and progression of renal injury in diabetes mellitus. Keywards: Diabetic nephropathy; Proteinuria; Tumor necrosis factor-

    Twelve-month observational study of children with cancer in 41 countries during the COVID-19 pandemic

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    Introduction Childhood cancer is a leading cause of death. It is unclear whether the COVID-19 pandemic has impacted childhood cancer mortality. In this study, we aimed to establish all-cause mortality rates for childhood cancers during the COVID-19 pandemic and determine the factors associated with mortality. Methods Prospective cohort study in 109 institutions in 41 countries. Inclusion criteria: children <18 years who were newly diagnosed with or undergoing active treatment for acute lymphoblastic leukaemia, non-Hodgkin's lymphoma, Hodgkin lymphoma, retinoblastoma, Wilms tumour, glioma, osteosarcoma, Ewing sarcoma, rhabdomyosarcoma, medulloblastoma and neuroblastoma. Of 2327 cases, 2118 patients were included in the study. The primary outcome measure was all-cause mortality at 30 days, 90 days and 12 months. Results All-cause mortality was 3.4% (n=71/2084) at 30-day follow-up, 5.7% (n=113/1969) at 90-day follow-up and 13.0% (n=206/1581) at 12-month follow-up. The median time from diagnosis to multidisciplinary team (MDT) plan was longest in low-income countries (7 days, IQR 3-11). Multivariable analysis revealed several factors associated with 12-month mortality, including low-income (OR 6.99 (95% CI 2.49 to 19.68); p<0.001), lower middle income (OR 3.32 (95% CI 1.96 to 5.61); p<0.001) and upper middle income (OR 3.49 (95% CI 2.02 to 6.03); p<0.001) country status and chemotherapy (OR 0.55 (95% CI 0.36 to 0.86); p=0.008) and immunotherapy (OR 0.27 (95% CI 0.08 to 0.91); p=0.035) within 30 days from MDT plan. Multivariable analysis revealed laboratory-confirmed SARS-CoV-2 infection (OR 5.33 (95% CI 1.19 to 23.84); p=0.029) was associated with 30-day mortality. Conclusions Children with cancer are more likely to die within 30 days if infected with SARS-CoV-2. However, timely treatment reduced odds of death. This report provides crucial information to balance the benefits of providing anticancer therapy against the risks of SARS-CoV-2 infection in children with cancer

    Search for strongly interacting massive particles generating trackless jets in proton-proton collisions at s = 13 TeV

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    A search for dark matter in the form of strongly interacting massive particles (SIMPs) using the CMS detector at the LHC is presented. The SIMPs would be produced in pairs that manifest themselves as pairs of jets without tracks. The energy fraction of jets carried by charged particles is used as a key discriminator to suppress efficiently the large multijet background, and the remaining background is estimated directly from data. The search is performed using proton-proton collision data corresponding to an integrated luminosity of 16.1 fb - 1 , collected with the CMS detector in 2016. No significant excess of events is observed above the expected background. For the simplified dark matter model under consideration, SIMPs with masses up to 100 GeV are excluded and further sensitivity is explored towards higher masses
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