Core Losses and Torque Ripple in IPM Machines: Dedicated Modeling and Design Trade Off

The proper combination of stator and rotor slot numbers is pursued in the design of interior permanent-magnet (IPM) motors with wide constant-power speed range. At high speed, in the flux-weakening region, the arising of stator and rotor iron losses due to magnetomotive-force (MMF) spatial harmonics limits the IPM motor performance. Torque ripple is another problem for this kind of machines, both at low and high speed. The numbers of stator slots and rotor equivalent slots have a major impact on both the loss and ripple aspects. A simplified model is proposed here in order to evaluate both problems with a general approach and point out the possible design tradeoff. With respect to previous models in the literature, both stator and rotor losses are included, and a more comprehensive approach is followed in the description of the rotor MMF harmonics. The model's effectiveness is tested through finite element analysis simulations and some experimental results. The proposed approach is useful for the selection of the IPM machine structure according to the specific requirements of the applicatio

Chest Ultrasound Helps to Diagnose Pulmonary Consolidations in Pediatric Patients

The diagnosis of pneumonia in pediatric patients relies on physical examination, blood tests, and chest X-rays. Physical examination, blood tests, and chest X-rays have a low accuracy, that is even greater in the critically ill. These limitations along with the risk of ionizing radiations, mandate the search for a safe diagnostic tool for patients with suspected pneumonia. Ultrasound (US) imaging offers several advantages over traditional radiographic techniques: it is non-invasive, painless, and involves minimal contact. In case of pulmonary parenchymal lesions, US is useful for differentiating pulmonary consolidation or atelectasis from lung masses and pleural lesions. Detection of air or fluid bronchograms at US and of pulmonary vessels with color flow imaging, is essential for the differential diagnosis of parenchymal consolidations. Furthermore US has a role in the evaluation of mediastinal masses and characterization of pleural fluid collection. Chest US is an ideal modality for serial examinations in rapidly evolving disease processes

Estrategias de seguridad lógica.

El gran uso de las computadoras y redes como medios de almacenamiento, transferencia y procesamiento de información se ha incrementado, al grado de convertirse en un elemento indispensable para el funcionamiento de diversas organizaciones (escuelas, empresas, centros de cómputo, hogares entre otros). Como consecuencia, la información en todas sus formas y estados se ha convertido en un activo de gran valor, el cual se debe proteger y asegurar para garantizar su integridad, confidencialidad, disponibilidad, e integridad. La inseguridad en la manipulación de la información, es cada día más vulnerable, por ejemplo un caso reciente fue la denuncia de un miembro del equipo de Obama (presidente electo de los estados unidos nov. 2008), quien denunció al Servicio Secreto de EE UU y al FBI un problema con un ordenador, que él imputaba a un virus informático. Sin embargo, cuando los agentes revisaron el sistema concluyeron que “una gran cantidad de información fue extraída de sus computadoras"

Waterborne outbreak of Norwalk-like virus gastroenteritis at a tourist resort, Italy.

In July 2000, an outbreak of gastroenteritis occurred at a tourist resort in the Gulf of Taranto in southern Italy. Illness in 344 people, 69 of whom were staff members, met the case definition. Norwalk-like virus (NLV) was found in 22 of 28 stool specimens tested. The source of illness was likely contaminated drinking water, as environmental inspection identified a breakdown in the resort water system and tap water samples were contaminated with fecal bacteria. Attack rates were increased (51.4%) in staff members involved in water sports. Relative risks were significant only for exposure to beach showers and consuming drinks with ice. Although Italy has no surveillance system for nonbacterial gastroenteritis, no outbreak caused by NLV has been described previously in the country