934 resultados para buck converter,conducted emission,2-150kHz,DC-microgrid


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Rural intersections account for 30% of crashes in rural areas and 6% of all fatal crashes, representing a significant but poorly understood safety problem. Transportation agencies have traditionally implemented countermeasures to address rural intersection crashes but frequently do not understand the dynamic interaction between the driver and roadway and the driver factors leading to these types of crashes. The Second Strategic Highway Research Program (SHRP 2) conducted a large-scale naturalistic driving study (NDS) using instrumented vehicles. The study has provided a significant amount of on-road driving data for a range of drivers. The present study utilizes the SHRP 2 NDS data as well as SHRP 2 Roadway Information Database (RID) data to observe driver behavior at rural intersections first hand using video, vehicle kinematics, and roadway data to determine how roadway, driver, environmental, and vehicle factors interact to affect driver safety at rural intersections. A model of driver braking behavior was developed using a dataset of vehicle activity traces for several rural stop-controlled intersections. The model was developed using the point at which a driver reacts to the upcoming intersection by initiating braking as its dependent variable, with the driver’s age, type and direction of turning movement, and countermeasure presence as independent variables. Countermeasures such as on-pavement signing and overhead flashing beacons were found to increase the braking point distance, a finding that provides insight into the countermeasures’ effect on safety at rural intersections. The results of this model can lead to better roadway design, more informed selection of traffic control and countermeasures, and targeted information that can inform policy decisions. Additionally, a model of gap acceptance was attempted but was ultimately not developed due to the small size of the dataset. However, a protocol for data reduction for a gap acceptance model was determined. This protocol can be utilized in future studies to develop a gap acceptance model that would provide additional insight into the roadway, vehicle, environmental, and driver factors that play a role in whether a driver accepts or rejects a gap.

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Introduction: Paediatric resuscitation is an intense, stressful andchallenging process performed in a specific surrounding. In theresuscitation room (RR), a dedicated pediatric team is not alwaysavailable and its composition varies according to local resources. Aregular review of the children admitted in the resuscitation room andthe assessment of various outcome measures are the basis of qualitycontrol (QC). The epidemiology of Potentially Life ThreateningPaediatric (LTP) emergencies admitted in a Swiss university hospitalhas never been reported. The aims of this study were to review theLTP emergency population with regards to origin, patients'demographics, reason for admission and final diagnosis, treatmentmodalities, critical events and outcome.Methods: A retrospective observational cohort study of prospectivelycollected data was conducted, including all LTP emergencies admittedover a period of 2 years in the RR of a Swiss university hospitalfunctioning as a tertiary level referral centre. Multiple variablesincluding indication for transfer, mode of pre-hospital transportation,diagnosis and the time spent in RR were assessed. Data assessmenttook place 2 years after the implementation of a quality control (QC)team assessing the pediatric resuscitations occurring within theinstitution on a monthly basis.Results: Out of 60 939 pediatric emergencies treated in LausanneUniversity Medical center over 2 years, a total of 277 LTP emergencies(0.46%) were admitted to the RR, including 160 boys and 117 girls,aged 6 days to 15.95 years (mean 6.69 years, median 5.06). The tablebelow illustrates in more details the identified problems, average age,time in hospital and outcome of both surgical and medical groups ofpatients.Conclusions: With the need for health care quality improvement andfinancial restrictions, an excellent knowledge of the characteristics ofLTP emergencies is unavoidable. A thorough understanding of theresuscitation process and humans resources involved can be achievedwith a systematic review of the cases. A dedicated quality control teamevaluating LTP emergencies in a hospital will identify areas forimprovement. A LTP registry at the national level would be of greatvalue in Switzerland.

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The Iowa Influenza Surveillance Network (IISN) was established in 2004, though surveillance has been conducted at the Iowa Department of Public Health. Schools and long-term care facilities report data weekly into a Web-based reporting system. Schools report the number of students absent due to illness and the total enrolled. Long-term care facilities report cases of influenza and vaccination status of each case. Both passively report outbreaks of illness, including influenza, to IDPH.

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In 1957, the Iowa State Highway Commission, with financial assistance from the aluminum industry, constructed a 220-ft (67-m) long, four-span continuous, aluminum girder bridge to carry traffic on Clive Road (86th Street) over Interstate 80 near Des Moines, Iowa. The bridge had four, welded I-shape girders that were fabricated in pairs with welded diaphragms between an exterior and an interior girder. The interior diaphragms between the girder pairs were bolted to girder brackets. A composite, reinforced concrete deck served as the roadway surface. The bridge, which had performed successfully for about 35 years of service, was removed in the fall of 1993 to make way for an interchange at the same location. Prior to the bridge demolition, load tests were conducted to monitor girder and diaphragm bending strains and deflections in the northern end span. Fatigue testing of the aluminum girders that were removed from the end spans were conducted by applying constant-amplitude, cyclic loads. These tests established the fatigue strength of an existing, welded, flange-splice detail and added, welded, flange-cover plates and horizontal web plate attachment details. This part, Part 2, of the final report focuses on the fatigue tests of the aluminum girder sections that were removed from the bridge and on the analysis of the experimental data to establish the fatigue strength of full-size specimens. Seventeen fatigue fractures that were classified as Category E weld details developed in the seven girder test specimens. Linear regression analyses of the fatigue test results established both nominal and experimental stress-range versus load cycle relationships (SN curves) for the fatigue strength of fillet-welded connections. The nominal strength SN curve obtained by this research essentially matched the SN curve for Category E aluminum weldments given in the AASHTO LRFD specifications. All of the Category E fatigue fractures that developed in the girder test specimens satisfied the allowable SN relationship specified by the fatigue provisions of the Aluminum Association. The lower-bound strength line that was set at two standard deviations below the least squares regression line through the fatigue fracture data points related well with the Aluminum Association SN curve. The results from the experimental tests of this research have provided additional information regarding behavioral characteristics of full-size, aluminum members and have confirmed that aluminum has the strength properties needed for highway bridge girders.

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The Iowa Influenza Surveillance Network (IISN) was established in 2004, though surveillance has been conducted at the Iowa Department of Public Health. Schools and long-term care facilities report data weekly into a Web-based reporting system. Schools report the number of students absent due to illness and the total enrolled. Long-term care facilities report cases of influenza and vaccination status of each case. Both passively report outbreaks of illness, including influenza, to IDPH.

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The Iowa Influenza Surveillance Network (IISN) was established in 2004, though surveillance has been conducted at the Iowa Department of Public Health. Schools and long-term care facilities report data weekly into a Web-based reporting system. Schools report the number of students absent due to illness and the total enrolled. Long-term care facilities report cases of influenza and vaccination status of each case. Both passively report outbreaks of illness, including influenza, to IDPH.

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PURPOSE: Positron emission tomography with (18)F-fluorodeoxyglucose (FDG-PET) was used to evaluate treatment response in patients with gastrointestinal stromal tumors (GIST) after administration of sunitinib, a multitargeted tyrosine kinase inhibitor, after imatinib failure. PATIENTS AND METHODS: Tumor metabolism was assessed with FDG-PET before and after the first 4 weeks of sunitinib therapy in 23 patients who received one to 12 cycles of sunitinib therapy (4 weeks of 50 mg/d, 2 weeks off). Treatment response was expressed as the percent change in maximal standardized uptake values (SUV). The primary end point of time to tumor progression was compared with early PET results on the basis of traditional Response Evaluation Criteria in Solid Tumors (RECIST) criteria. RESULTS: Progression-free survival (PFS) was correlated with early FDG-PET metabolic response (P < .0001). Using -25% and +25% thresholds for SUV variations from baseline, early FDG-PET response was stratified in metabolic partial response, metabolically stable disease, or metabolically progressive disease; median PFS rates were 29, 16, and 4 weeks, respectively. Similarly, when a single FDG-PET positive/negative was considered after 4 weeks of sunitinib, the median PFS was 29 weeks for SUVs less than 8 g/mL versus 4 weeks for SUVs of 8 g/mL or greater (P < .0001). None of the patients with metabolically progressive disease subsequently responded according to RECIST criteria. Multivariate analysis showed shorter PFS in patients who had higher residual SUVs (P < .0001), primary resistance to imatinib (P = .024), or nongastric GIST (P = .002), regardless of the mutational status of the KIT and PDGFRA genes. CONCLUSION: Week 4 FDG-PET is useful for early assessment of treatment response and for the prediction of clinical outcome. Thus, it offers opportunities to individualize and optimize patient therapy.

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This paper presents a model of the Stokes emission vector from the ocean surface. The ocean surface is described as an ensemble of facets with Cox and Munk's (1954) Gram-Charlier slope distribution. The study discusses the impact of different up-wind and cross-wind rms slopes, skewness, peakedness, foam cover models and atmospheric effects on the azimuthal variation of the Stokes vector, as well as the limitations of the model. Simulation results compare favorably, both in mean value and azimuthal dependence, with SSM/I data at 53° incidence angle and with JPL's WINDRAD measurements at incidence angles from 30° to 65°, and at wind speeds from 2.5 to 11 m/s.

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Line converters have become an attractive AC/DC power conversion solution in industrial applications. Line converters are based on controllable semiconductor switches, typically insulated gate bipolar transistors. Compared to the traditional diode bridge-based power converters line converters have many advantageous characteristics, including bidirectional power flow, controllable de-link voltage and power factor and sinusoidal line current. This thesis considers the control of the lineconverter and its application to power quality improving. The line converter control system studied is based on the virtual flux linkage orientation and the direct torque control (DTC) principle. A new DTC-based current control scheme is introduced and analyzed. The overmodulation characteristics of the DTC converter are considered and an analytical equation for the maximum modulation index is derived. The integration of the active filtering features to the line converter isconsidered. Three different active filtering methods are implemented. A frequency-domain method, which is based on selective harmonic sequence elimination, anda time-domain method, which is effective in a wider frequency band, are used inharmonic current compensation. Also, a voltage feedback active filtering method, which mitigates harmonic sequences of the grid voltage, is implemented. The frequency-domain and the voltage feedback active filtering control systems are analyzed and controllers are designed. The designs are verified with practical measurements. The performance and the characteristics of the implemented active filtering methods are compared and the effect of the L- and the LCL-type line filteris discussed. The importance of the correct grid impedance estimate in the voltage feedback active filter control system is discussed and a new measurement-based method to obtain it is proposed. Also, a power conditioning system (PCS) application of the line converter is considered. A new method for correcting the voltage unbalance of the PCS-fed island network is proposed and experimentally validated.

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Taajuusmuuttajat aiheuttavat toimintansa seurauksena runsaasti laajakaistaisia sähkömagneettisia häiriöitä. Häiriöt etenevät sekä johtumalla että säteilemällä ja ne ovat seurausta pääasiassa taajuusmuuttajien toimintaan perustuvista nopeista kytkentäilmiöistä sekä puolijohdekomponenttien epälineaarisuuksista. Sähkömagneettisille häiriöille määritellään suurimmat sallitut tasot useissa EMC-standardeissa. Taajuusmuuttajia koskevia EMC-standardia on neljä; tuotestandardi EN 61800-3, harmonisia virtoja pienjänniteverkoissa käsittelevä EN 61000-3-12 sekä yleiset standardit EN 61000-6-1, -6-2 ja EN 61000-6-3, -6-4. Tämän diplomityön tarkoituksena on tutkia ja koota yhteen edellä mainittujen standardien sisältämät vaatimukset. Työn pääpaino on kohdistettu häiriöpäästöille asetettuihin vaatimuksiin, sillä häiriöiden sietoon liittyvien vaatimusten täyttäminen ei taajuusmuuttajien kohdalla yleensä tuota ongelmia.

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Dentre as espécies frutíferas do bioma cerrado destaca-se a cagaiteira (Eugenia dysenterica DC., Myrtaceae), cujos frutos são consumidos in natura ou processados. Os frutos, folhas e casca apresentam propriedades medicinais, a madeira é utilizada em pequenas construções e carvão. Objetivou-se caracterizar frutos e árvores da espécie por amostragem de populações de plantas existentes no Sudeste de Goiás. Coletaram-se 1344 frutos de 112 plantas de 10 sub-populações para caracterização física dos mesmos e dados de 95 árvores, visando a sua descrição morfológica. Constatou-se variação significativa ao nível de 1% de probabilidade entre as 112 plantas para todos os caracteres de fruto, assim como entre plantas dentro de subpopulação e entre as médias de subpopulações. A média para a variável peso de fruto e número de sementes por fruto foi de 12,67g e 1,70, respectivamente. Os valores máximos e mínimos encontrados para a variável altura de planta foram, respectivamente, 11,0 m e 4,10 m e para diâmetro de copa foram de 10,30 m e 1,80m.

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O programa de melhoramento genético de acerola, na Universidade Estadual de Londrina, iniciou-se em 1992, com a implatação de um pomar clonal constituído de genótipos selecionados no Norte do Paraná. As cultivares UEL 3-Dominga , UEL 4-Lígia, UEL 5-Natália são resultados de 5 ciclos de avaliações, onde foram considerados: precocidade, produtividade, conteúdo de vitamina C nos frutos, tolerância a pragas e doenças, tamanho e aparência dos frutos. As cultivares UEL 3-Dominga e UEL 5- Natália, destacam-se pela produtividade das plantas, conteúdo de vitamina C e pelo tamanho do fruto. Em Londrina, a frutificação dessas cultivares concentra-se nos meses de novembro a março. A cultivar UEL 4-Lígia destaca-se pela precocidade e produtividade que, em Londrina, se concentra nos meses de outubro a março. A cultivar UEL 3-Dominga apresenta peso médio de frutos igual a 6,31g, Vitamina C igual a 2906 e 1250 mg/100g em frutos verdes e maduros, respectivamente, acidez igual a 694,34 mg/100g e Brix igual a 9,2º. A cultivar UEL 4-Lígia apresenta peso médio dos frutos igual a 7,85g, vitamina C igual a 3579 e 1458 mg/100g em frutos verdes e maduros, respectivamente, acidez igual a 1110 mg/100g e Brix igual a 7,85º. A cultivar UEL 5-Natália apresenta peso médio dos frutos igual a 7,47g, Vitamina C igual a 3134,5 e 1098 mg/100g em frutos verdes e maduros, respectivamente, acidez igual a 725 mg/100g e Brix igual a 7,6º. Estas três cultivares são indicadas para plantio no Norte do Estado do Paraná.

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Muitas frutíferas do cerrado apresentam potencial para a exploração econômica e, dentre elas, a cagaiteira destaca-se pelas suas diversas utilidades, sendo os seus frutos consumidos in natura ou na forma de sucos, sorvetes, licores e geléias, tornando-se, assim, de interesse realizar pesquisas com esta espécie. Neste trabalho, mudas de cagaiteira (Eugenia dysenterica DC) produzidas em tubetes com diferentes volumes (50 cm³, 120 cm³ e 228 cm³) e três tipos de substratos {solo + terriço de mata + vermiculita (1:1:2); solo + terriço de mata + vermiculita (1:1:2) + 1g de termofosfato Yoorin por litro de substrato; e substrato comercial Plantmax} foram plantadas no campo e avaliadas quanto ao crescimento em altura e diâmetro e percentagem de sobrevivência. O delineamento adotado foi o de blocos completos casualizados, em esquema fatorial 3 x 3, utilizando-se de cinco repetições e cinco plantas por parcela. Verificou-se que as mudas produzidas a partir do substrato solo + terriço de mata + vermiculita, com e sem adubação química, apresentaram maior crescimento em altura e em diâmetro, em todas as épocas de avaliação. As mudas obtidas em tubetes contendo diferentes tipos e volumes de substrato apresentaram taxas de sobrevivência entre 76% e 100%, aos 540 dias após o plantio no campo. O crescimento em altura e em diâmetro foi lento, atingindo os valores médios de 46,267 cm e 0,637 cm, respectivamente, aos 540 dias. Esse diâmetro pode ser considerado adequado para a realização da enxertia nesta espécie.

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A morfologia interna e a viabilidade de sementes de acerola (Malpighia emarginata DC.) foram estudadas utilizando-se o tetrazólio (cloreto de 2, 3, 5 trifenil tetrazólio). Dos clones testados, o Flórida Sweet foi o que apresentou a menor percentagem de sementes com embriões normais (10%) como também em reação às sementes sem embriões (8%) e o maior percentagem de sementes com embriões deformados (81%). O clone 07-OS apresentou maior percentagem de sementes com embriões normais (51%) e um número considerado elevado de sementes sem embriões (34%). Os demais clones apresentaram valores intermediários. Para todos os clones avaliados, as sementes com embriões normais apresentaram 100% de embriões viáveis. Essas sementes submetidas ao teste de tetrazólio por um período de 12 horas, apresentaram-se com uma coloração vermelha intensa, considerada ideal para a avaliação positiva da viabilidade das sementes. Estes resultados não podem, entretanto, ser tomados para prognóstico e o cálculo da taxa de germinação e dormência, apenas indicando que as sementes estão vivas.

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Pulsewidth-modulated (PWM) rectifier technology is increasingly used in industrial applications like variable-speed motor drives, since it offers several desired features such as sinusoidal input currents, controllable power factor, bidirectional power flow and high quality DC output voltage. To achieve these features,however, an effective control system with fast and accurate current and DC voltage responses is required. From various control strategies proposed to meet these control objectives, in most cases the commonly known principle of the synchronous-frame current vector control along with some space-vector PWM scheme have been applied. Recently, however, new control approaches analogous to the well-established direct torque control (DTC) method for electrical machines have also emerged to implement a high-performance PWM rectifier. In this thesis the concepts of classical synchronous-frame current control and DTC-based PWM rectifier control are combined and a new converter-flux-based current control (CFCC) scheme is introduced. To achieve sufficient dynamic performance and to ensure a stable operation, the proposed control system is thoroughly analysed and simple rules for the controller design are suggested. Special attention is paid to the estimationof the converter flux, which is the key element of converter-flux-based control. Discrete-time implementation is also discussed. Line-voltage-sensorless reactive reactive power control methods for the L- and LCL-type line filters are presented. For the L-filter an open-loop control law for the d-axis current referenceis proposed. In the case of the LCL-filter the combined open-loop control and feedback control is proposed. The influence of the erroneous filter parameter estimates on the accuracy of the developed control schemes is also discussed. A newzero vector selection rule for suppressing the zero-sequence current in parallel-connected PWM rectifiers is proposed. With this method a truly standalone and independent control of the converter units is allowed and traditional transformer isolation and synchronised-control-based solutions are avoided. The implementation requires only one additional current sensor. The proposed schemes are evaluated by the simulations and laboratory experiments. A satisfactory performance and good agreement between the theory and practice are demonstrated.