Direct torque control for dual three-phase induction motor drives

A direct torque control (DTC) strategy for dual three-phase induction motor drives is discussed in this paper. The induction machine has two sets of stator three-phase windings spatially shifted by 30 electrical degrees. The DTC strategy is based on a predictive algorithm and is implemented in a synchronous reference frame aligned with the machine stator flux vector. The advantages of the discussed control strategy are constant inverter switching frequency, good transient and steady-state performance, and low distortion of machine currents with respect to direct self-control (DSC) and other DTC schemes with variable switching frequency. Experimental results are presented for a 10-kW DTC dual three-phase induction motor drive prototype

New Stationary Frame Control Scheme for Three Phase PWM Rectifiers Under Unbalanced Voltage Dips Conditions

A new stationary frame control scheme for three-phase pulsewidth-modulation (PWM) rectifiers operating under unbalanced voltage dips conditions is proposed in this paper. The proposed control scheme regulates the instantaneous active power at the converter poles to minimize the harmonics of the input currents and the output voltage ripple. This paper's novelty is the development of a new current-reference generator implemented directly in stationary reference frame. This allows using proportional sinusoidal signal integrator (P-SSI) controllers for simultaneous compensation of both positive and negative current sequence components. No phase-locked loop (PLL) strategies and coordinate transformations are needed for the proposed current-reference generator. Experimental results are presented for a 20-kV A alternative current (ac)/direct current (dc) converter prototype to demonstrate the effectiveness of the proposed control scheme. A comparison with two other existing control techniques is also performed. Fast dynamic performance with small dc-link voltage ripple and input sinusoidal currents are obtained with this control scheme, even under severe voltage dips operating conditions

H-Bridge Converter as Basic Switching Topology Workbench in Power Electronics Teaching

This article deals with an effective power electronics learning setup based on a Full-Bridge converter used to teach electrical energy conversion experimentally. In the proposed learning by doing methodology, the hardware and the software are properly mixed in order to obtain an easy-to-use experimental learning environment. In this paper, the H-Bridge is the fundamental brick to build students’ knowledge on the main topics of power electronics converter circuit in different operative conditions. This H-Bridge comes with a reconfigurable output LCL to achieve several basic DC-DC powerconverters topologies. Converter current and voltage switching behavior can be investigated using the proposed setup. Furthermore, the friendly hardware and software set-up allows studying the converter modulation and control techniques of the different power electronics circuits

A test-rig to evaluate a dual-3-phase induction motor drive

The potential advantages of multi-phase solutions over the conventional 3-phase ones have been widely described in the literature. However, their feasibilities and performances have been poorly described and proven. The main goal of this paper is the design and implementation of a test rig to evaluate some control policies for a double-3-phase induction motor drive, a multiphase drive with interest in Electric Vehicle (EV) applications

Chemotherapy against cancer during pregnancy : a systematic review on neonatal outcomes

Background: The concomitant incidence of cancer and pregnancy has increased in recent years because of the increase in maternal age at the time of the 1st pregnancy. The diagnosis of cancer in a pregnant woman causes ethical and therapeutic problems for both the patient and the physician. The main aim of this paper is to describe the available evidence concerning the short-and longterm neonatal impact of chemotherapy given to pregnant women. Methods:The relevant publications in English were identified by a systematic review of MEDLINE and PubMed for the last 15 years. The search strategy included "cancer[Title/Abstract] OR tumor[Title/Abstract] AND pregnancy[Title/Abstract] OR pregnant[Title/Abstract] AND embryo[Title/Abstract] or fetus[Title/Abstract] or neonate[Title/Abstract] or newborn[Title/Abstract] or pediatric[Title/Abstract] or child[Title/Abstract] AND English[lang]." Results:An analysis of the literature showed that only the administration of chemotherapy during the embryonic stage of conceptus is dangerous and can lead to the termination of the pregnancy. When the disease is diagnosed in the 2nd or 3rd trimester of gestation or when it is possible to delay the initiation of chemotherapy beyond the 14th week, the risk of severe problems for the fetus are low, and pregnancy termination is not required. Conclusion: Data regarding the final outcome of children who have received in utero chemotherapy seem reassuring. Only the administration in the embryonal stage of conceptus is dangerous and can lead to the termination of pregnancy. When the disease is diagnosed in the 2nd or 3rd trimester of gestation or when it is possible to delay the initiation of chemotherapy beyond the 14th week, the risk of severe problems for the fetus are low and pregnancy termination is not needed. Increased knowledge of how to minimize the risks of chemotherapy can reduce improper management including unnecessary termination of pregnancy, delayed maternal treatment, and iatrogenic preterm delivery

Molecular and Functional Characterization of Three Different Postzygotic Mutations in PIK3CA-Related Overgrowth Spectrum (PROS) Patients: Effects on PI3K/AKT/mTOR Signaling and Sensitivity to PIK3 Inhibitors

BACKGROUND PIK3CA-related overgrowth spectrum (PROS) include a group of disorders that affect only the terminal portion of a limb, such as type I macrodactyly, and conditions like fibroadipose overgrowth (FAO), megalencephaly-capillary malformation (MCAP) syndrome, congenital lipomatous asymmetric overgrowth of the trunk, lymphatic, capillary, venous, and combined-type vascular malformations, epidermal nevi, skeletal and spinal anomalies (CLOVES) syndrome and Hemihyperplasia Multiple Lipomatosis (HHML). Heterozygous postzygotic PIK3CA mutations are frequently identified in these syndromes, while timing and tissue specificity of the mutational event are likely responsible for the extreme phenotypic variability observed. METHODS: We carried out a combination of Sanger sequencing and targeted deep sequencing of genes involved in the PI3K/AKT/mTOR pathway in three patients (1 MCAP and 2 FAO) to identify causative mutations, and performed immunoblot analyses to assay the phosphorylation status of AKT and P70S6K in affected dermal fibroblasts. In addition, we evaluated their ability to grow in the absence of serum and their response to the PI3K inhibitors wortmannin and LY294002 in vitro. RESULTS AND CONCLUSION: Our data indicate that patients' cells showed constitutive activation of the PI3K/Akt pathway. Of note, PI3K pharmacological blockade resulted in a significant reduction of the proliferation rate in culture, suggesting that inhibition of PI3K might prove beneficial in future therapies for PROS patients

Pre-implant magnetic resonance and transrectal ultrasound imaging in high-dose-rate prostate brachytherapy : comparison of prostate volumes, craniocaudal extents, and contours

Purpose: The purpose of this study was to compare the prostate contours drawn by two radiation oncologists and one radiologist on magnetic resonance (MR) and transrectal ultrasound (TRUS) images. TRUS intra- and inter-fraction variability as well as TRUS vs. MR inter-modality and inter-operator variability were studied. Material and methods: Thirty patients affected by localized prostate cancer and treated with interstitial high-dose-rate (HDR) prostate brachytherapy at the National Cancer Institute in Milan were included in this study. Twenty-five patients received an exclusive two-fraction (14 Gy/fraction) treatment, while the other 5 received a single 14 Gy fraction as a boost after external beam radiotherapy. The prostate was contoured on TRUS images acquired before (virtual US) and after (real US) needle implant by two radiation oncologists, whereas on MR prostate was independently contoured by the same radiation oncologists (MR1, MR2) and by a dedicated radiologist (MR3). Absolute differences of prostate volumes ( 06V) and craniocaudal extents ( 06dz) were evaluated. The Dice's coefficient (DC) was calculated to quantify spatial overlap between MR contours. Results: Significant difference was found between Vvirtual and Vlive (p < 0.001) for the first treatment fractions and between VMR1 and VMR2 (p = 0.043). Significant difference between cranio-caudal extents was found between dzvirtual and dzlive (p < 0.033) for the first treatment fractions, between dzvirtual of the first treatment fractions and dzMR1 (p < 0.001) and between dzMR1 and dzMR3 (p < 0.01). Oedema might be responsible for some of the changes in US volumes. Average DC values resulting from the comparison MR1 vs. MR2, MR1 vs. MR3 and MR2 vs. MR3 were 0.95 \ub1 0.04 (range, 0.82-0.99), 0.87 \ub1 0.04 (range, 0.73-0.91) and 0.87 \ub1 0.04 (range, 0.72-0.91), respectively. Conclusions: Our results demonstrate the importance of a multiprofessional approach to TRUS-guided HDR prostate brachytherapy. Specific training in MR and US prostate imaging is recommended for centers that are unfamiliar with HDR prostate brachytherapy

Mechanical design of rotors for permanent magnet high speed electric motors for turbocharger applications

Realization of electrically boosted turbochargers requires electric motors capable of operating at very high speeds. These motors often use a permanent magnet rotor with the magnets retained within an interference fit external sleeve. Whilst it is possible to model such systems numerically, these models are an inefficient tool for design optimization. Current analytical models of rotors typically consider the stresses induced by the shrink fit of the sleeve separately from the stresses generated by centripetal forces due to rotation. However, such an approach ignores the frictional interaction between the components in the axial direction. This paper presents an analytical model that simultaneously accounts for interaction between the magnet and outer sleeve in both the radial and axial directions at designed interference and with the assembly subjected to centripetal and thermal loads. Numerical models presented show that with only moderate coefficients of friction and rotor lengths; axial load transfer between magnet and sleeve takes place over a short distance at the ends of the assembly. The paper then demonstrates how the analytical model aids definition of a feasible set of rotor designs and selection of an optimum design

Lung volume reduction surgery versus endobronchial valves: a randomised controlled trial

BACKGROUND: Lung volume reduction surgery (LVRS) and bronchoscopic lung volume reduction (BLVR) with endobronchial valves can improve outcomes in appropriately selected patients with emphysema. However, no direct comparison data exist to inform clinical decision making in people who appear suitable for both procedures. Our aim was to investigate whether LVRS produces superior health outcomes when compared with BLVR at 12 months. METHODS: This multicentre, single-blind, parallel-group trial randomised patients from five UK hospitals, who were suitable for a targeted lung volume reduction procedure, to either LVRS or BLVR and compared outcomes at 1 year using the i-BODE score. This composite disease severity measure includes body mass index, airflow obstruction, dyspnoea and exercise capacity (incremental shuttle walk test). The researchers responsible for collecting outcomes were masked to treatment allocation. All outcomes were assessed in the intention-to-treat population. RESULTS: 88 participants (48% female, mean±sd age 64.6±7.7 years, forced expiratory volume in 1 s percent predicted 31.0±7.9%) were recruited at five specialist centres across the UK and randomised to either LVRS (n=41) or BLVR (n=47). At 12 months follow-up, the complete i-BODE was available in 49 participants (21 LVRS/28 BLVR). Neither improvement in the i-BODE score (LVRS -1.10±1.44 versus BLVR -0.82±1.61; p=0.54) nor in its individual components differed between groups. Both treatments produced similar improvements in gas trapping (residual volume percent predicted: LVRS -36.1% (95% CI -54.6- -10%) versus BLVR -30.1% (95% CI -53.7- -9%); p=0.81). There was one death in each treatment arm. CONCLUSION: Our findings do not support the hypothesis that LVRS is a substantially superior treatment to BLVR in individuals who are suitable for both treatments

Validation of techniques to mitigate copper surface contamination in CUORE

In this article we describe the background challenges for the CUORE experiment posed by surface contamination of inert detector materials such as copper, and present three techniques explored to mitigate these backgrounds. Using data from a dedicated test apparatus constructed to validate and compare these techniques we demonstrate that copper surface contamination levels better than 10E-07 - 10E-08 Bq/cm2 are achieved for 238U and 232Th. If these levels are reproduced in the final CUORE apparatus the projected 90% C.L. upper limit on the number of background counts in the region of interest is 0.02-0.03 counts/keV/kg/y depending on the adopted mitigation technique.Comment: 10 pages, 6 figures, 6 table