Capacitors usually determine the overall lifetime of power converters since they are mainly responsible for breakdowns. Their failure results from the deterioration of their dielectric, the ...production of gases, and, eventually, their explosion. This process leads to an increase in the capacitor equivalent series resistance (ESR) and a decrease in its capacitance value for both electrolytic and metalized polypropylene film (MPPF) capacitors. In this paper, a novel noninvasive technique for capacitor diagnostic in Boost converters is presented. It can easily be applied online and even in real time, and it is suitable for the operation in both continuous current mode (CCM) and discontinuous current mode (DCM). The technique is based on the double estimations of the ESR and the capacitance, improving the diagnostic reliability. This way, predictive maintenance is provided, and it is possible to alarm for capacitor replacement, avoiding downtime. As the method is intended for railway high-power applications, it has been conceived neither to add any additional hardware in the power stage nor to even slightly modify it. To demonstrate and validate the effectiveness and accuracy of the proposed technique, several simulations and experimental results are discussed in a small prototype. In this prototype, the software for real-time estimation is programmed in a low-cost digital signal processor (DSP).
Abstract Lead poisoning has been reportedly linked to a high risk of learning disabilities, aggression and criminal offenses. To study the association between lead exposure and antisocial/delinquent ...behavior, a cross-sectional study was conducted with 173 Brazilian youths aged 14–18 and their parents ( n = 93), living in impoverished neighborhoods of Bauru-SP, with high criminality indices. Self-Reported Delinquency (SRD) and Child Behavior Checklist (CBCL) questionnaires were used to evaluate delinquent/antisocial behavior. Body lead burdens were evaluated in surface dental enamel acid microbiopsies. The dental enamel lead levels (DELL) were quantified by graphite furnace atomic absorption spectrometry (GFAAS) and phosphorus content was measured using inductively coupled plasma optical emission spectrometry (ICP-OES). Logistic regression was used to identify associations between DELL and each scale defined by CBCL and SRD scores. Odd ratios adjusted for familial and social covariates, considering a group of youths exposed to high lead levels (≥ 75 percentile), indicated that high DELL is associated with increased risk of exceeding the clinical score for somatic complaints, social problems, rule-breaking behavior and externalizing problems (CI 95%). High DELL was not found to be associated with elevated SRD scores. In conclusion, our data support the hypothesis that high-level lead exposure can trigger antisocial behavior, which calls for public policies to prevent lead poisoning.
The aim of this paper is to present two very simple, cheap, and practical experimental techniques that are able to estimate the capacitor equivalent circuit for a wide range of frequencies and ...temperatures. The capacitor equivalent circuit considerably changes with temperature, aging, and frequency. Therefore, knowledge of their equivalent circuit at their operating conditions can lead to better design proposals. In addition, knowledge of the evolution of the equivalent series resistance (ESR) with temperature is essential for the development of reliable online fault diagnosis techniques. This issue is particularly important for aluminum electrolytic capacitors, since they are the preferred capacitor type in power electronics applications and simultaneously one of the most critical components in such applications. To implement the first technique, it is necessary to put the capacitor under test in series with a resistor and connect it to a sinusoidal voltage. The second technique requires a simple charge-discharge circuit. After acquiring both capacitors' current and voltage through an oscilloscope, which is connected to a PC with Matlab software, it is possible to compute both capacitor capacitance and resistance using the least mean square ( LMS ) algorithm. To simulate the variation of capacitor case temperature, a very simple prototype was used. Several experimental results were obtained to evaluate the accuracy and precision of the two experimental techniques.
This study seeks to present and discuss the different Challenges of Online Learning of Laboratory Subjects as well as provide a solution for enhancement. The researchers survey to gather basic ...information that is essential for the collection of data such as the profile of the respondents based on their age, gender, year level, and location of current address. Also, they seek to determine the challenges being encountered by the students and how these factors affect their learning of skills in laboratory subjects, together with providing solutions for the mentioned dilemma.
AlGaN/GaN-superlattice based diode structures under study were grown by metal organic chemical vapour deposition, then implanted with two different Eu ion beam fluences, and further submitted to high ...temperature and high pressure thermal annealing treatments. The effects of Eu implantation and annealing on the diode structure emission characteristics were investigated at 14 K and room temperature. Eu3+ luminescence was observed in both Eu-implanted and annealed samples, being the most intense emission assigned to the 5D0 → 7F2 transition in the red spectral region (~621 nm), in line with the main observed behaviour of Eu3+ ions implanted in GaN layers. The combined excitation/emission spectra revealed that the measured intraionic emission corresponds to an overlap of two principal emitting centres which can be excited through above and below GaN bandgap. In addition, a considerable reduction of the non-radiative channels was observed for the diode structure implanted with the highest Eu fluence, inducing a higher thermal stability of the intra-4f6 lines intensity. In contrast to GaN layers, the perceived Eu3+ red emission observed at room temperature was found to be strongly sensitive to the GaN above bandgap excitation (out of the resonance conditions) suggesting that additional energy transfer between the AlGaN/GaN superlattice excitons and the Eu3+ ions occurs, therefore widening the excitation pathways for the red luminescence.
•Eu implantation/annealing effects on AlGaN/GaN-superlattice diode optical properties.•Implantation/annealing conditions favour the multiple Eu3+ centre optical activation.•Higher thermal stability of the intra-4f 6 lines for the highest Eu fluence diode.•Faster decay obtained for the yellow luminescence versus red Eu3+ luminescence.•The 325 nm excitation is the most efficient for providing the perceived red emission.
This article is an update of the requirements of a specialist breast centre, produced by EUSOMA and endorsed by ECCO as part of Essential Requirements for Quality Cancer Care (ERQCC) programme, and ...ESMO.
To meet aspirations for comprehensive cancer control, healthcare organisations must consider the requirements in this article, paying particular attention to multidisciplinarity and patient-centred pathways from diagnosis, to treatment, to survivorship.•The centrepiece of this article is the requirements section, comprising definitions; multidisciplinary structure; minimum case, procedure and staffing volumes; and detailed descriptions of the skills of, and resources needed by, members and specialisms in the multidisciplinary team in a breast centre.•These requirements are positioned within narrative on European breast cancer epidemiology, the standard of care, challenges to delivering this standard, and supporting evidence, to enable a broad audience to appreciate the importance of establishing these requirements in specialist breast centres.
This paper presents a study developed on a three-phase 11-MW synchronous motor with a solid salient-pole rotor of a blower drive system of a blast furnace at the Companhia Siderurgica Belgo-Mineira, ...Joao Monlevade, Brazil. A mechanical model including motor, gears, couplings, and blower is used in a simulation study to evaluate the torsional dynamics and stresses during motor startup and voltage sag conditions. In addition, the operation of the synchronous motor under voltage sag is analyzed with a comparative study between complete and approximated models of the motor. The utilization of a dynamic voltage restorer to protect the drive system under this abnormal situation is also evaluated.
A virus isolated from Olea europaea L. grown in Portugal, was identified as a member of the species Tobacco necrosis virus D (TNV-D, genus Necrovirus, family Tombusviridae), based on the molecular ...and serological properties of the purified virus particles. The genomic region encoding the coat protein (CP) of this isolate (named GP isolate) was amplified by RT-PCR and the cDNA was cloned and sequenced. The CP gene encodes a predicted protein of 269 amino acids showing high identity (86.2%) to TNV-D coat protein sequence. Phylogenetic analysis based on necroviruses CP sequences, confirmed GP as a TNV-D isolate. The alignment with homologous TNV-D CP sequences revealed four conserved amino acids involved in Ca(2+) binding as well as the plant virus icosahedral capsid protein "S' signature. Based on the determined nucleotide sequence, specific primers were designed and successfully used in RT-PCR for virus diagnosis in naturally infected olive trees.
Germline ATM mutations are suggested to contribute to predisposition to prostate cancer (PrCa). Previous studies have had inadequate power to estimate variant effect sizes.
To precisely estimate the ...contribution of germline ATM mutations to PrCa risk.
We analysed next-generation sequencing data from 13 PRACTICAL study groups comprising 5560 cases and 3353 controls of European ancestry.
Variant Call Format files were harmonised, annotated for rare ATM variants, and classified as tier 1 (likely pathogenic) or tier 2 (potentially deleterious). Associations with overall PrCa risk and clinical subtypes were estimated.
PrCa risk was higher in carriers of a tier 1 germline ATM variant, with an overall odds ratio (OR) of 4.4 (95% confidence interval CI: 2.0–9.5). There was also evidence that PrCa cases with younger age at diagnosis (<65 yr) had elevated tier 1 variant frequencies (pdifference = 0.04). Tier 2 variants were also associated with PrCa risk, with an OR of 1.4 (95% CI: 1.1–1.7).
Carriers of pathogenic ATM variants have an elevated risk of developing PrCa and are at an increased risk for earlier-onset disease presentation. These results provide information for counselling of men and their families.
In this study, we estimated that men who inherit a likely pathogenic mutation in the ATM gene had an approximately a fourfold risk of developing prostate cancer. In addition, they are likely to develop the disease earlier.
We aimed to detect new cases of konzo and monitor cyanogen exposure from cassava flour in communities previously affected by konzo epidemics in Nampula Province, northern Mozambique. Other objectives ...were to detect subclinical upper motor neuron damage in schoolchildren and test a new kit to measure urinary thiocyanate concentration. In 1999 and 2000, we carried out active and passive case detection for konzo in Memba and Mogincual Districts. In July and October, 1999, we collected cassava flour from 30 houses in three communities and measured cyanogen concentrations with a picrate kit. In October 1999, we examined all schoolchildren in three communities for ankle clonus and measured urinary thiocyanate concentration in thirty schoolchildren in each of five communities with a picrate kit. We found 27 new cases of konzo in Mogincual District. Mean total cyanogen concentrations in cassava flour varied between both seasons and years, but were always high, ranging from 26 to 186 ppm. Very high mean levels at three sites in November 1998 and July 1999 were probably due to low rainfall in the 1997–1998 season. The proportion of schoolchildren with ankle clonus varied from 8 to 17%. The new picrate kit for urinary thiocyanate worked well; mean concentrations in schoolchildren ranged from 225 to 384 μmol l
−1. Konzo and sub-clinical upper motor neuron damage persist in poor rural communities in northern Mozambique, associated with high cyanogen concentrations in cassava flour and high urinary thiocyanate concentrations in schoolchildren.
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