Digital current control of electric arc furnace by parallel modular three-phase IGBT inverters

Electric Arc Furnaces (EAF) have been traditionally fed by means of a medium to low voltage transformer (between grid and electrodes), where the main control action consists of modifying the electrodes vertical position. This simple and robust arrangement suffers from grid \u201cpollution\u201d and poor current control. Current control of EAF by means of three phase modular inverters is reported here for the first time. Several control issues are analyzed and addressed, ranging from pure control (e.g. addressing load imbalance and limits due to low switching frequency) to system management. Two different current regulation methods are proposed and compared, namely a scalar approach and a vector method using \u201cquasi zero phase lag\u201d sampling and gains adaptation. The second technique achieves very good control, leading to lower oversizing of the converter stage and process optimization. Simulations have been performed including digital controller architecture, converters and arc electrical behavior. Preliminary experimental measurements are reported based on an actual plant

Ethical approach and professional responsibility in workplace drug testing: An update on the eff ectiveness of the Italian current legislation

Introduction: The Italian legislation on workplace drug testing (WDT), applied to “at-risk workers” since October 2008, calls for mandatory procedures about screening tests on urine performed by occupational health specialists and confirmation tests by gas chromatography/mass spectrometry performed by forensic laboratories. Aim: Evaluating the impact of the current law on WDT on trends of drug use in workers and discuss some ethical implications and professional responsibility connected to the management of the toxicological controls. Materials and Methods: The toxicological analyses performed from 2001 to 2014 on 73,656 workers (aged between 19 and 65 years; 92% males and 8% females), mainly employed in transports were selected for the present study. Confirmation analysis has been requested on urine samples (n = 3934) previously identified as positive for one or more drugs by immunoassay screening tests for opiates, methadone, cannabinoids, cocaine, buprenorphine, amphetamines, and analogues. Results: Relevant differences were observed, both in the incidence and in the type of drugs used, before and after the mandatory law application. At screening the positive urine were n = 2455 during 2001-2008 and n = 1479 since 2009. Among those of this second period, only 14.6% were confirmed as true positive versus the 74% of urine confirmed during 2001-2008. Moreover, the polydrug use, since 2009, decrease from 32% to 8% of cases. Cannabis and cocaine were most frequently used, alone or together with other drugs. The use of opiates, methadone and amphetamines has been observed for <5% of the workers without significant differences before and after 2009. Conclusion: To explain the decrease of our epidemiological data, two factors were considered as the prevailing ones: The deterrent effect of the mandatory nature of the drug tests and the behavior often adopted by the occupational physicians in order to avoid professional liability or disputes by workers representatives. The ethical principles, that occupational health physicians and toxicologists need to employ, to avoid the violation of the workers’ rights were discussed

Rehabilitation impact indices and their independent predictors: A systematic review

10.1136/bmjopen-2013-003483BMJ Open39

Self-adaptive high-frequency injection based sensorless control for interior permanent magnet synchronous motor drives \u2020

Abstract: An auto-tuning and self-adaptation procedure for High Frequency Injection (HFI) based position and speed estimation algorithms in Interior Permanent Magnet Synchronous Motor (IPMSM) drives is proposed in this paper. Analytical developments show that, using conventional approaches, the dynamics of the high-frequency tracking loop varies with differential inductances, which in turn depend on the machine operating point. On-line estimation and adaptation of the small signal gain of the loop is proposed here, allowing accurate auto-tuning of the sensorless control scheme which does not rely on a priori knowledge of the machine parameters. On-line adaptation of Phase-Locked Loop (PLL) gains and of the injected voltage magnitude is also possible, leading to important advantages from the performance, loss and acoustic point of view. The theoretical basis of the method has been introduced first and the main concept demonstrated by means of simulations. Implementation has been carried out using the hardware of a commercial industrial drive and two Interior Permanent Magnet Synchronous Motors, namely a prototype and an off-the-shelf machine. Experimental tests demonstrate the feasibility and effectiveness of the proposal

Effects of Prior Fasting on Fat Oxidation during Resistance Exercise

International Journal of Exercise Science 11(2): 827-833, 2018. Prior research has demonstrated that the percentage of fuel utilization contributed by CHO compared to fat rises with an increase in exercise intensity. The role of food intake prior to exercise has been well studied and fasting prior to exercise generally increases reliance on fat as fuel. However, data on the role of fasting prior to resistance exercise is limited. Therefore, the purpose of this study was to assess the effects of one bout of resistance training in a fasted state compared to ingestion of standardized meal on fat and carbohydrate utilization. Twelve female (n = 12, age = 20.1 ± 0.79 yrs, height = 67.0 ± 2.63 in, weight = 143 ± 21.8 lbs) NCAA Division 1 athletes participated in the study. Each participant completed one 10 hour fasted resistance training session and one postprandial resistance training session. The respiratory exchange ratio (RER) and METs were measured using a Cosmed K4b2portable metabolic cart (Cosmed, Rome, Italy) and heart rate was measured by a Polar H1 heart rate monitor. Participants consumed the prescribed food, waited 15 minutes, and then completed three sets of five repetitions of bench press, back squat, and military press at 60% of their 1-repetition maximum. The mean fasted RER was significantly lower than postprandial for back squat (p=0.01) and military press (p=0.02), but not bench press (p=0.19). There was no difference in METs, RPE, or HR between fasted and postprandial trials for any exercise. Results suggest that fasted resistance exercise relies more heavily on fat metabolism than carbohydrate

Factor demand linkages, technology shocks, and the business cycle

This paper argues that factor demand linkages can be important for the transmission of both sectoral and aggregate shocks. We show this using a panel of highly disaggregated manufacturing sectors together with sectoral structural VARs. When sectoral interactions are explicitly accounted for, a contemporaneous technology shock to all manufacturing sectors implies a positive response in both output and hours at the aggregate level. Otherwise there is a negative correlation, as in much of the existing literature. Furthermore, we find that technology shocks are important drivers of the business cycle

Central Versus Peripheral Cardiovascular Risk in Metabolic Syndrome

Individuals with metabolic syndrome (MetS; i.e., three of five of the following risk factors (RFs): elevated blood pressure, waist circumference, triglycerides, blood glucose, or reduced HDL) are thought to be prone to serious cardiovascular disease and there is debate as to whether the disease begins in the peripheral vasculature or centrally. This study investigates hemodynamics, cardiac function/morphology, and mechanical properties of the central (heart, carotid artery) or peripheral [total peripheral resistance (TPR), forearm vascular bed] vasculature in individuals without (1–2 RFs: n = 28), or with (≥3 RFs: n = 46) MetS. After adjustments for statin and blood pressure medication use, those with MetS had lower mitral valve E/A ratios (<3 RFs: 1.24 ± 0.07; ≥3 RFs: 1.01 ± 0.04; P = 0.025), and higher TPR index (<3 RFs: 48 ± 2 mmHg/L/min/m2; ≥3 RFs: 53 ± 2 mmHg/L/min/m2; P = 0.04). There were no differences in heart size, carotid artery measurements, cardiovagal baroreflex, pulse-wave velocity, stroke volume index, or cardiac output index due to MetS after adjustments for statin and blood pressure medication use. The use of statins was associated with increased inertia in the brachial vascular bed, increased HbA1c and decreased LDL cholesterol. The independent use of anti-hypertensive medication was associated with decreased predicted VO2max, triglycerides, diastolic blood pressure, interventricular septum thickness, calculated left ventricle mass, left ventricle posterior wall thickness, and left ventricle pre-ejection period, but increased carotid stiffness, HDL cholesterol, and heart rate. These data imply that both a central cardiac effect and a peripheral effect of vascular resistance are expressed in MetS. These data also indicate that variance in between-group responses due to pharmacological treatments are important factors to consider in studying cardiovascular changes in these individuals

Analysis of the saltwater wedge in a coastal karst aquifer with a double conduit network, numerical simulations and sensitivity analysis

We investigate the long-distance salinity in a dual permeability coastal karst aquifer with a double conduit network using a three-dimensional variable-density groundwater flow and multispecies transport SEAWAT model. Sensitivity analyses were used to evaluate the impact of the parameters and boundary conditions on the modeling saltwater wedge in a karstic aquifer situated in the Cuban land territory, including hydraulic conductivity, vertical anisotropy and salinity concentration; both in the conduits network and the fractured medium. These analyses indicated that hydraulic conductivity of the fractured medium and salt concentration were the ones that have a stronger effect on saltwater intrusion in a karstic aquifer. We also show results of the three-dimensional numerical simulations on groundwater salinity for different scenarios with the variabilities of the important parameters and compare results with electric conductivity profiles measured in a well

Activation of NF-kappaB/Rel transcription factors in human primary peripheral blood mononuclear cells by interleukin 7.

Pathways that regulate the activation of NF-kappaB/Rel transcription factors are known to include signaling through a number of cytokine receptors. Interleukin 7 (IL-7), produced by bone marrow and other stromal cells, is a key factor for differentiation and survival in the lymphoid and other compartments. We found that human recombinant IL-7 induced NF-kappaB/Rel activation, analyzed by electrophoretic mobility shift assay (EMSA), in human peripheral blood T lymphocytes from healthy donors. Induced complexes included p65 and p50 NF-kappaB/Rel subunits. These results demonstrate for the first time that IL-7 can participate in signaling leading to NF-kappaB/Rel activation