AC Variable-Speed Drives and Noise of Magnetic Origin: A Strategy to Control the PWM Switching Effects

The presented developments concern the definition of a method to characterize simply the pulse width-modulated (PWM) switching three-phase harmonic systems. This characterization, which makes it possible to control the components generated by the switching anticipating the negative effects possibly generated, is exploited in the context of reducing the noise of magnetic origin that can affect the operating of AC variable speed drives

Las ondas electromagnéticas superficiales y su relación con las anomalías de una red difracción

Fil: Brudny, Vera Leonor. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Influence of the continuous casting process of TIN-ZINC-LEAD bronze on the wear of the graphite crystallizer

The research conducted in this paper concerns the influence of the continuous casting process of tin-zinc-lead bronze on the wear of the graphite crystallizer. Observations and testing of the external surface of the cast rods indicate their good quality, without casting defects. No excessive surface degradation was observed on the inner surface of the crystallizers after casting. It was assessed that the surface quality of the crystallizer would be acceptable for further use, despite stuck residue, mainly in the crystallization zone

Update on women in physics in Argentina

Data collected 10 years ago in Argentina concluded that women in physics were underrepresented in many instances and that a “crystal ceiling” was firmly in place. We have collected updated data for several indicators and compared them with those obtained 10 years ago. Although there is not a clear conclusion to be drawn from this comparison, we try to explain the results within the framework of the changes in scientific policies in Argentina.Fil: Brudny, Vera Leonor. Universidad de Buenos Aires. Departamento de Ciencias Exactas; ArgentinaFil: Lagorio, Cecilia. Universidad Nacional de Mar del Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata; ArgentinaFil: Frechero, Marisa Alejandra. Universidad Nacional del Sur. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; ArgentinaFil: Tamarit, Francisco. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Física "Enrique Gaviola"; Argentin

Influence of the continuous casting process of TIN-ZINC-LEAD bronze on the wear of the graphite crystallizer

The research conducted in this paper concerns the influence of the continuous casting process of tin-zinc-lead bronze on the wear of the graphite crystallizer. Observations and testing of the external surface of the cast rods indicate their good quality, without casting defects. No excessive surface degradation was observed on the inner surface of the crystallizers after casting. It was assessed that the surface quality of the crystallizer would be acceptable for further use, despite stuck residue, mainly in the crystallization zone

Non Invasive Sensors for Monitoring the Efficiency of AC Electrical Rotating Machines

This paper presents a non invasive method for estimating the energy efficiency of induction motors used in industrial applications. This method is innovative because it is only based on the measurement of the external field emitted by the motor. The paper describes the sensors used, how they should be placed around the machine in order to decouple the external field components generated by both the air gap flux and the winding end-windings. The study emphasizes the influence of the eddy currents flowing in the yoke frame on the sensor position. A method to estimate the torque from the external field use is proposed. The measurements are transmitted by a wireless module (Zig-Bee) and they are centralized and stored on a PC computer

The Participants Evaluation of Screening Colonoscopy

Introduction. The awareness of the need to carry out screening programs for the early colorectal cancer detection increases in the Polish society. Colonoscopy is a common tool used in these programs. Theaim of this paper is to present the participants' evaluation of the screening program for the early colorectal cancer detection with the use of screening colonoscopy. Material and methods. 1442 participants aged 40-65 were examined. A day before colonoscopy the patient took a cleansing agent based on polyethylene glycol (Fortrans). Most examinations were performed under an anaesthetic with the use of midazolam, which was administered orally a quarter before the examination. The degree of the large intestine cleansing was assessed using the 4-degree scale (very good, good, sufficient and poor cleansing). A very important issue in every screening examination is the acceptance of the basic examination tool by the participants. Based on this fact, the authors of the program proposed that directly after the examination the patients filled in a questionnaire where they assessed the usefulness of the examination, the burdensomeness of the preparation process, their tolerance of screening colonoscopy, a general feeling regarding the examination and declared if they would took part in that examination once again and if they would recommend it to other people. Results. The majority of participants think the examination is useful, well-tolerated, while the preparation process is not burdensome, performed in a very positive atmosphere and they would agree to the examination once again.Wstęp. W społeczeństwie polskim wzrasta świadomość potrzeby prowadzenia programu badań przesiewowych dla wczesnego wykrywania nowotworów złośliwych jelita grubego. Powszechnie stosowanym narzędziem tych programów jest kolonoskopia. Celempracy była ocena programu badań przesiewowych dla wczesnego wykrywania nowotworów jelita grubego przy użyciu kolonoskopii przesiewowej przez jej uczestników. Materiał i metody. Badania wykonano u 1442 uczestników w wieku od 40 do 65 lat. Dzień przed kolonoskopią badany przyjmował środek oczyszczający jelito grube oparty na glikolu polietylenowym (Fortrans). Większość badań wykonywana była w znieczuleniu z zastosowaniem midazolamu, który podawano doustnie kwadrans przed badaniem. Stopień oczyszczenia jelita określono w czterostopniowej skali jako dobre, wystarczające, słabe i nieoczyszczone. Bardzo ważnym zagadnieniem w każdym programie przesiewowym jest akceptacja przez uczestników podstawowego narzędzia badawczego. Między innymi z tego powodu autorzy programu zaproponowali, aby bezpośrednio po badaniu uczestnicy wypełniali ankietę, w której oceniali przydatność badania, uciążliwość przygotowania, tolerancję kolonoskopii przesiewowej, ogólne wrażenie związane z badaniem oraz składali deklarację czy poddali by się temu badaniu ponownie i czy polecili by to badanie innym. Wyniki. Uczestnicy w swej znakomitej większości uważają, że badanie to jest użyteczne, dobrze tolerowane

Second harmonic generation in suspensions of spherical particles

We study the second harmonic generation (SHG) in a suspension of small spherical particles confined within a slab, assuming undepleted pump and applying (i) single scattering approximation and (ii) diffusion approximation. In the case (i), the angular diagram, the differential and total crossections of the SHG process, as well as the average cosine of SH scattering angle are calculated. In the case (ii), the average SH intensity is found to show no explicit dependence on the linear scattering properties of the suspension. The average intensity of SH wave scales as I_0 L / \Lambda_2 in both cases (i) and (ii), where I_0 is the intensity of the incident wave, L is the slab thickness, and \Lambda_2 is an intensity-dependent "SH scattering" length.Comment: PDF, 20 pages, 4 figure