966 resultados para common mode current


Relevância:

40.00% 40.00%

Publicador:

Resumo:

The refugee crisis will be dominating discussions at the EU Summit. Cooperating with third countries, especially Turkey; border controls, hotspots, relocation and returns will all feature. These discussions reflect that the EU is in crisis response mode, attempting to deal with the sheer scale of the current flows and the rapidly evolving situation, as well as internal divisions.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

Mode of access: Internet.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

In this presentation we will discuss the implications of the so called Nonlinear Shannon Limit. We will compare technologies including new fibres for long haul transmission and techniques to expand the capacity of existing standard single mode fibres.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

Four-leg dc-ac power converters are widely used for the power grids to manage grid voltage unbalance caused by the interconnection of single-phase or three-phase unbalanced loads. These converters can further be connected in parallel to increase the overall power rating. The control of these converters poses a particular challenge if they are placed far apart with no links between them (e.g., in islanded microgrids). This challenge is studied in this paper with each four-leg converter designed to have improved common current sharing and selective voltage-quality enhancement. The common current sharing, including zero sequence component, is necessary since loads are spread over the microgrid and they are hence the common responsibility of all converters. The voltage-quality enhancement consideration should however be more selective since different loads have different sensitivity levels towards voltage disturbances. Converters connected to the more sensitive load buses should therefore be selectively triggered for compensation when voltage unbalances at their protected buses exceed the predefined thresholds. The proposed scheme is therefore different from conventional centralized schemes protecting only a common bus. Simulation and experimental results obtained have verified the effectiveness of the proposed scheme when applied to a four-wire islanded microgrid.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

Nowadays, there is a boom in the use of electrification. Electric vehicles are gaining interest worldwide due to various factors, including climate and environmental awareness. In this thesis, a step-down isolated power supply for electric tractors is investigated, specifically the phase-shifted full-bridge (PSFB) DC-DC with synchronous rectification and zero-voltage switching (ZVS). This converter was selected for its high-power capacity with high efficiency. A 3500 W PSFB converter with peak current control (PCCM) is designed and modeled in MATLAB. The input voltage range is from 550 V to 820 V and the output voltage range is limited to 9 V to 16 V with a maximum output current of 250 A. All components were commercially designed and selected, including magnetics for the high-frequency transformer and inductors, taking into account loss calculations. Zero voltage switching for the lagging leg is achieved at 13% to 100% load. The proven efficiency of the converter is around 90

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Among the numerous problems that are common to the Latin-American metropolises, such as the deep socio-spatial segregation, the impressive territorial fragmentation and the real estate valorisation that overvalues some territories, whilst it depreciates others, we have chosen to focus on the management of the metropolitan regions. That question clearly indicates that due to the great current changes of the economical restructuring - a process that strengthened the capitalist logic of social development - the traditional form of thinking urban planning has found its limits. Consequently, this issue of metropolitan management shows the need to look for new ways of metropolitan administration that can answer to the The main metropolitan regions of South America: Buenos Aires, Sao Paulo and Santiago form our references to characterize the recent changes from a territorial point of view on the one hand; and relative to the new determinations of the metropolis on the other hand. This leads us to discuss the challenges that metropolitan management face in a scenario of governability fragmentation.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Current HIV vaccine approaches are focused on immunogens encoding whole HIV antigenic proteins that mainly elicit cytotoxic CD8+ responses. Mounting evidence points toward a critical role for CD4+ T cells in the control of immunodeficiency virus replication, probably due to cognate help. Vaccine-induced CD4+ T cell responses might, therefore, have a protective effect in HIV replication. In addition, successful vaccines may have to elicit responses to multiple epitopes in a high proportion of vaccinees, to match the highly variable circulating strains of HIV. Using rational vaccine design, we developed a DNA vaccine encoding 18 algorithm-selected conserved, ""promiscuous"" ( multiple HLA-DR-binding) B-subtype HIV CD4 epitopes - previously found to be frequently recognized by HIV-infected patients. We assessed the ability of the vaccine to induce broad T cell responses in the context of multiple HLA class II molecules using different strains of HLA class II-transgenic mice (-DR2, -DR4, -DQ6 and -DQ8). Mice displayed CD4+ and CD8+ T cell responses of significant breadth and magnitude, and 16 out of the 18 encoded epitopes were recognized. By virtue of inducing broad responses against conserved CD4+ T cell epitopes that can be recognized in the context of widely diverse, common HLA class II alleles, this vaccine concept may cope both with HIV genetic variability and increased population coverage. The vaccine may thus be a source of cognate help for HIV-specific CD8+ T cells elicited by conventional immunogens, in a wide proportion of vaccinees.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Biological nitrogen fixation (BNF) constitutes a valuable source of this nutrient for the common bean Phaseolus vulgaris L and cowpea Vigna unguiculata (L.) Walp., being its avaibility affected by mineral N in the soil solution. The objectives of this work were to evaluate the effects of nitrogen rate, as urea, on symbiotic fixation of N(2) in common bean and cowpea plants, using the isotopic technique, and quantifying the relative contributions of N sources symbiotic N(2) fixation, soil native nitrogen and urea N on the growth of the common bean and cowpea. Non nodulating soybean plants were used as standard. The research was carried out in greenhouse, using pots with 5 kg of soil from a Typic Haplustox (Dystrophic Red Yellow Latosol). The experimental design was completely randomized blocks, with 30 treatments and three replications, arranged in 5x3x2 factorial outline. The treatments consisted of five N rates: 2, 15, 30, 45 and 60 mg N kg(-1) soil; three sampling times: 23, 40 and 76 days after sowing (DAS) and two crops: common bean and cowpea. The BNF decreased with increase N rates, varying from 81.5% to 55.6% for cowpea, and from 71.9% to 55.1% for common bean. The symbiotic N(2) fixation in cowpea can substitute totally the nitrogen fertilization. The nitrogen absorption from soil is not affected by nitrogen fertilizer rate. The N recovery from fertilizer at 76 DAS was of 60.7% by common bean, and 57.1% by cowpea. The symbiotic association in common bean needs the application of a starting dose (40 kg N ha(-1)) for economically acceptable yields.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Welded equipment for cryogenic applications is utilized in chemical, petrochemical, and metallurgical industries. One material suitable for cryogenic application is austenitic stainless steel, which usually doesn`t present ductile/brittle transition temperature, except in the weld metal, where the presence of ferrite and micro inclusions can promote a brittle failure, either by ferrite cleavage or dimple nucleation and growth, respectively. A 25-mm- (1-in.-) thick AISI 304 stainless steel base metal was welded with the SAW process using a 308L solid wire and two kinds of fluxes and constant voltage power sources with two types of electrical outputs: direct current electrode positive and balanced square wave alternating current. The welded joints were analyzed by chemical composition, microstructure characterization, room temperature mechanical properties, and CVN impact test at -100 degrees C (-73 degrees F). Results showed that an increase of chromium and nickel content was observed in all weld beads compared to base metal. The chromium and nickel equivalents ratio for the weld beads were always higher for welding with square wave AC for the two types of fluxes than for direct current. The modification in the Cr(eq)/Ni(eq) ratio changes the delta ferrite morphology and, consequently, modifies the weld bead toughness at lower temperatures. The oxygen content can also affect the toughness in the weld bead. The highest absorbed energy in a CVN impact test was obtained for the welding condition with square wave AC electrical output and neutral flux, followed by DC(+) electrical output and neutral flux, and square wave AC electrical output and alloyed flux.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

An adequate supply of nitrogen is essential for high yield of common bean seeds; however, the responses to this nutrient in no-tillage systems can vary in function of the species and the amount of straw present. The aim of this research was to evaluate response of the common bean to N in no-tillage systems over maize, millet and Brachiaria brizantha crop residues. Three experiments were conducted, one for each gramineous species. The experimental design was a randomized block in a 5x2x2 factorial scheme, with five N doses (0, 30, 60, 90, 120 kg ha(-1)), in two distinct stadia during the vegetative development (3(rd) and 6(th) trifoliate leaf) and two common bean cultivars (IPR Juriti and Perola), with four replications. The IPR Juriti produced a greater number of pods per plant and showed lower mass per 100 seeds than Perola. It did not show variation in bean yield when the sidedressing N application was carried out in the 3(rd) or 6(th) trifoliate leaf stadia. Based on the obtained results, one concludes that the seed productivity of common beans increases linearly with N doses in a no-tillage system over maize residues.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Lung cancer remains the most common cause of cancer-related mortality in Scotland, accounting for 28.9% of all cancer deaths in 2007. Current guidelines recommend assessment of patient fitness and operability by a multidisciplinary team when selecting management options. Two of the most important prognostic markers are the stage of disease and ECOG performance status. In 1996, the International Association for the Study of Lung Cancer (IASLC) launched a worldwide TNM staging project to create international databases that would be used to continue the excellent efforts of Dr. Cliff Mountain, who pioneered this approach to lung cancer staging in 1973. Successive iterations of tumor, nodule, metastasis (TNM) staging for lung cancer have addressed shortcomings identified by the oncology community. Similarly, the IASLC recognized that it is important that further revisions continue to be made to ensure that the international staging system for lung cancer remains fit for its purpose. The last work of the International Staging Committee (ISC) was the conduct of the study that informed the seventh edition of the international staging system for lung cancer, in 2010. This review of image and staging in non small cell lung cancer (NSCLC), includes a summary of the different noninvasive tests currently available for staging non small cell lung cancer.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

This review describes the current multidisciplinary management of gastrointestinal stromal tumor (GIST), which is the most common sarcoma of the gastrointestinal tract. Before 2001, surgery was the only effective therapy for GIST. The discovery of the central role of KIT proto-oncogene mutations in the pathogenesis of this tumor, and the development of specific inhibitors of KIT tyrosine kinase (TK) function, has changed the paradigm of treatment for GISTs. Imatinib and sunitinib are TK inhibitors with activity against GISTs. Their major established role in GIST is in the treatment of advanced disease. A growing body of literature and clinical experience support the potential perioperative use of these drugs. The adjuvant use of imatinib is based on retrospective series and limited prospective studies demonstrating that imatinib reduces the risk of recurrence. Ongoing studies are further defining the length of adjuvant therapy, as well as identifying the patients that could achieve the best results. Neoadjuvant treatment often decreases the tumor size, allowing a less morbid surgery, appears to be safe and beneficial for some patients, and therefore deserves further study.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Background: EUS is being increasingly utilized for the diagnosis of choledocholithiasis and microlithiasis, especially in patients with biliary colic. Simultaneously, there is also a rising interest in the use of EUS for therapeutic interventions. Objectives: Our goal was to assess the effectiveness of EUS-directed common bile duct (CBD) stone removal to compare its safety and effectiveness with ERCP-directed intervention. Design: interim results of a prospective, randomized, single-center blinded clinical trial. Setting: A single tertiary care referral center. Patients: Fifty-two patients with uncomplicated CBD stones were prospectively randomized to CBD cannulation and stone removal under EUS or ERCP guidance. Main Outcome Measurements and Interventions: Primary outcome measure was the rate of successful cannulation of the CBD. Secondary Outcome measures included Successful removal of stones and overall complication rates. Results: CBD cannulation followed by stone extraction was successful in 23 of 26 patients (88.5%) in the EUS group (1) versus 25 of 26 patients (96.2%) in the ERCP group (11) (95% CI, -27.65%, 9.88%). Overall, there were 3 complications in the EUS group and 4 complications in the ERCP group. Limitation: The current study is an interim report from a single center report and performed by a single operator. Conclusions: Our preliminary analysis indicates that Outcomes following EUS-guided CBD stone retrieval are equivalent to those following ERCP EUS-related adverse events are similar to those following ERCP. ERCP and EUS-guided stone retrieval appears to be equally effective for therapeutic interventions of the bile duct. Additional studies are required to validate these preliminary results and to determine predictors of success of EUS-guided stone removal. (Gastrointest Endosc 2009;69:238-43.)