Performance of common-mode chokes

A low-cost method for experimental investigation of common-mode chokes for reducing high-frequency motor ground-currents of inverter-based drive systems of several hundred kW is presented. It provides a powerful tool during the design stage of such chokes to verify their predicted performance. The method draws from the mainly capacitive behavior of machines at very high frequencies. Results of experimental tests for drives with peak ground-current amplitudes of more than 60 Amperes, carried out on a 4 kW test-bed, are presented. They confirm the feasibility of such tests as well as the capability of small, inexpensive, single-turn chokes to effectively reduce the ground-current

A multicenter, randomised, double-blind, placebo-controlled, prospective crossover trial

Objective To evaluate the efficacy and safety of bupropion in the treatment of apathy in Huntington’s disease (HD). Methods In this phase 2b multicentre, double-blind, placebo-controlled crossover trial, individuals with HD and clinical signs of apathy according to the Structured Clinical Interview for Apathy—Dementia (SCIA-D), but not depression (n = 40) were randomized to receive either bupropion 150/300mg or placebo daily for 10 weeks. The primary outcome parameter was a significant change of the Apathy Evaluation Scale (AES) score after ten weeks of treatment as judged by an informant (AES-I) living in close proximity with the study participant. The secondary outcome parameters included changes of 1. AES scores determined by the patient (AES-S) or the clinical investigator (AES-C), 2. psychiatric symptoms (NPI, HADS-SIS, UHDRS-Behavior), 3. cognitive performance (SDMT, Stroop, VFT, MMSE), 4. motor symptoms (UHDRS-Motor), 5. activities of daily function (TFC, UHDRS-Function), and 6. caregiver distress (NPI-D). In addition, we investigated the effect of bupropion on brain structure as well as brain responses and functional connectivity during reward processing in a gambling task using magnetic resonance imaging (MRI). Results At baseline, there were no significant treatment group differences in the clinical primary and secondary outcome parameters. At endpoint, there was no statistically significant difference between treatment groups for all clinical primary and secondary outcome variables. Study participation, irrespective of the intervention, lessened symptoms of apathy according to the informant and the clinical investigator. Conclusion Bupropion does not alleviate apathy in HD. However, study participation/placebo effects were observed, which document the need for carefully controlled trials when investigating therapeutic interventions for the neuropsychiatric symptoms of HD. Trial registration ClinicalTrials.gov 0191496

Design of an electrochemical micromachining machine

Electrochemical micromachining (μECM) is a non-conventional machining process based on the phenomenon of electrolysis. μECM became an attractive area of research due to the fact that this process does not create any defective layer after machining and that there is a growing demand for better surface integrity on different micro applications including microfluidics systems, stress-free drilled holes in automotive and aerospace manufacturing with complex shapes, etc. This work presents the design of a next generation μECM machine for the automotive, aerospace, medical and metrology sectors. It has three axes of motion (X, Y, Z) and a spindle allowing the tool-electrode to rotate during machining. The linear slides for each axis use air bearings with linear DC brushless motors and 2-nm resolution encoders for ultra precise motion. The control system is based on the Power PMAC motion controller from Delta Tau. The electrolyte tank is located at the rear of the machine and allows the electrolyte to be changed quickly. This machine features two process control algorithms: fuzzy logic control and adaptive feed rate. A self-developed pulse generator has been mounted and interfaced with the machine and a wire ECM grinding device has been added. The pulse generator has the possibility to reverse the pulse polarity for on-line tool fabrication.The research reported in this paper is supported by the European Commission within the project “Minimizing Defects in Micro-Manufacturing Applications (MIDEMMA)” (FP7-2011-NMPICT- FoF-285614)

Design of a pulse power supply unit for micro-ECM

Electrochemical micro-machining (μECM) requires a particular pulse power supply unit (PSU) to be developed in order to achieve desired machining performance. This paper summarises the development of a pulse PSU meeting the requirements of μECM. The pulse power supply provides tens of nanosecond pulse duration, positive and negative bias voltages and a polarity switching functionality. It fulfils the needs for tool preparation with reversed pulsed ECM on the machine. Moreover, the PSU is equipped with an ultrafast overcurrent protection which prevents the tool electrode from being damaged in case of short circuits. The developed pulse PSU was used to fabricate micro-tools out of 170 μm WC-Co alloy shafts via micro-electrochemical turning and drill deep holes via μECM in a disk made of 18NiCr6. The electrolyte used for both processes was a mixture of sulphuric acid and NaNO3 aqueous solutions.The research reported in this paper is supported by the European Commission within the project “Minimizing Defects in Micro-Manufacturing Applications (MIDEMMA)” (FP7-2011-NMP-ICT-FoF-285614

Faunal Subsistence Strategies Among Initial Period Coastal Fishers at the Gramalote Site in the Moche Valley of Peru

This faunal analysis focuses on vertebrate remains from the northern coastal site of Gramalote in the lower Moche Valley of Peru. Gramalote dates to the Initial Period (1800-900 BC), a time of great change due to a rise of inland agricultural and increasing sedentism. This intrasite analysis of fauna at Gramalote seeks to contextualize potential subsistence shifts through time. Subsistence specialization regarding fish exploitation of coastal fishers is explored through faunal analysis of vertebrates at this site. For an ecological perspective, this project examines the application of Moseley\u27s Maritime Foundations of Andean Civilization and Optimal Foraging Theory models. The sample analyzed comes from a stratified unit Unit 18A, resulting from the 2005 excavations at the site directed by Jesus Briceño Rosario (Briceño and Billman 2008). The total sample consisted of 22,940animal bones, of which 14,542 are the focus of this analysis. To understand possible chronological shifts in the importance of fish, three questions were examined. How does the vertebrate composition by class compare between the 2005 sample and the data previously reported by Pozorski? For Unit 18A, does the relative importance of fish steadily increase over time? How can we add the variable of depositional context to our evaluation of change over time

Normalization-Based Approach to Electric Motor BVR Related Capacitances Computation

Electrical discharge machining bearing currents that may occur within electric machines of variable-speed-drive motor systems have been recognized for a long time. One key influential factor, the machine's capacitive voltage divider “bearing-voltage-ratio” (BVR) strongly depends on the rotor-to-frame and the stator winding-to-rotor capacitances; these are, in turn, affected by the design of the machine's stator slot. This paper presents an approach to improve the accuracy with which these capacitances can be estimated. It is based on the well-known plate capacitance equation which is then corrected by normalization functions. The functions are defined by extensive parameter studies using electrostatic finite element method (FEM) simulations. The final expressions not only allow for the prediction of the stator-winding-to-rotor and rotor-to-frame capacitances, they are also readily applicable. Thereby, they facilitate, for example, the clear-cut study of the sensitivity of the BVR towards changes in the different stator slot parameters.Post-print / Final draf

Thermal Finite Element Modeling and Simulation of a Squirrel-Cage Induction Machine

Finite element models of electrical machines allow insights in electrothermal stresses which endanger the insulation system of the machine. This paper presents a thermal finite element model of a 3.7 kW squirrel-cage induction machine. The model resolves the conductors and the surrounding insulation materials in the stator slots. A set of transient thermal scenarios is defined and measured in the machine laboratory. These data are used to assess the finite element model

Ипотечное страхование как драйвер роста ипотечного кредитования

В статье рассматривается необходимость и факторы развития ипотечного кредитования. Приводится краткий анализ альтернативных методов разрешения жилищного вопроса для россиян. Дается соответствующая оценка ипотечного страхования как фактора развития ипотечного кредитования