Error evaluation of thermistor linearizing circuits

PostprintA simple designing method for linearizing circuits, based on one resistor, is presented. The errors caused by this circuit are calculated, considering the temperature range and the thermistor parameters. These errors are used as a basis for comparing the quality of active linearizing circuits. In many cases, complex circuits have similar errors to single resistor linearizing circuits. It is shown that the exponential approximation is one of the most important error sources. The authors propose to use more precise models. The relationship between the parameters of the exponential model and those of other models is discussed

Quantitative Modeling of the Impact of Video Content in the ITU-T G.1070 Video Quality Estimation Function

In this paper we present an enhancement to the video quality estimation model described in ITU-T Recommendation G.1070 “Opinion model for video-telephony applications”, in order to include the impact of video content, for different display sizes and codecs. This enhancement provides a much better approximation of the model results with respect to the perceptual MOS values for a wide range of video contents. SAD (Sum of Absolute Differences) is used as an estimation of the video spatial-temporal activity, and is included as a new parameter in the model. The results are based on more than 1500 processed video clips, coded in MPEG-2 and H.264/AVC, in bit rate ranges from 50 kb/s to 12 Mb/s, in SD, VGA, CIF and QCIF display formats

Including the Effects of Video Content in the ITU-T G.1070 Video Quality Function

In this paper we present an enhancement to the video quality estimation model described in ITU-T Recommendation G.1070 “Opinion model for video-telephony applications”, including the effect of video content in the G.1070 video quality function. This enhancement provides a much better approximation of the model results with respect to the perceptual MOS values. SAD (Sum of Absolute Differences) is used as an estimation of the video spatial-temporal activity. The results are based on more than 1500 processed video clips, coded in MPEG-2 and H.264/AVC, in bit rate ranges from 50 kb/s to 12 Mb/s, in SD, VGA, CIF and QCIF display formats

Estudio de la medida de la calidad perceptual de video

En el presente trabajo se realiza un estudio del estado del arte, en el ámbito de la medida objetiva de la calidad perceptual de video. El video digital, distribuido a través de redes de comunicaciones, sufre varios tipos de distorsión durante el proceso de adquisición, compresión, procesamiento, transmisión y reproducción. Por ejemplo, las técnicas utilizadas habitualmente en la codificación digital de video introducen pérdida de información, para reducir el ancho de banda necesario para su transmisión, lo que genera distorsiones. Por otro lado, las redes de paquetes sobre las que se transporta el video (por ejemplo Internet, aunque también redes de área local LAN, las redes extendidas WAN y las redes inalámbricas), pueden introducir distorsiones adicionales, debido a las demoras, los errores y las pérdidas de paquetes, entre otros factores. La medida objetiva de la calidad perceptual de video es necesaria para diversos tipos de aplicaciones, algunas de las cuales se describen a continuación. Nota : Es el trabajo final para el Diploma de Estudios Avanzados (DEA) en Ingeniería Telemática, de la Universidad de Vigo, Españ

Immunoregulatory mechanisms and Chagas' disease

During the course of experimental Chagas' disease, several immune disorders occur. In the acute phase, T and B cell plyclonal activation is associated to immunossupression. At the chronic stage. T cells - of the TH2 subset - participate to the pathology characteristic of Chagas'disease. Data obtained after infection of BALB/Xid mice suggest that polyclonal activation may be dependent on B1 (CD5) cell activation. Moreover, these mice fail to develop the pathological features of the chronic infection. Control of lymphokine secretion might play a key role in the clinical status of Chagas'disease

GPU-based 3D iceball modeling for fast cryoablation simulation and planning

Purpose The elimination of abdominal tumors by percutaneous cryoablation has been shown to be an effective and less invasive alternative to open surgery. Cryoablation destroys malignant cells by freezing them with one or more cryoprobes inserted into the tumor through the skin. Alternating cycles of freezing and thawing produce an enveloping iceball that causes the tumor necrosis. Planning such a procedure is difficult and time-consuming, as it is necessary to plan the number and cryoprobe locations and predict the iceball shape which is also influenced by the presence of heating sources, e.g., major blood vessels and warm saline solution, injected to protect surrounding structures from the cold. Methods This paper describes a method for fast GPU-based iceball modeling based on the simulation of thermal propagation in the tissue. Our algorithm solves the heat equation within a cube around the cryoprobes tips and accounts for the presence of heating sources around the iceball. Results Experimental results of two studies have been obtained: an ex vivo warm gel setup and simulation on five retrospective patient cases of kidney tumors cryoablation with various levels of complexity of the vascular structure and warm saline solution around the tumor tissue. The experiments have been conducted in various conditions of cube size and algorithm implementations. Results show that it is possible to obtain an accurate result within seconds. Conclusion The promising results indicate that our method yields accurate iceball shape predictions in a short time and is suitable for surgical planning

Modelo de estimación de calidad de Video: video quality experts groups

The digital video and multimedia content distributed via telecommunication networks suffers from several types of distortion or degradation during the process of acquisition, compression, processing, transmission and reproduction. One of the key factors in the success of a multimedia system or service is to achieve an acceptable quality of experience for the user, depending on the application. Video quality is one of the key factors in the overall quality of the experience perceived by users. For the purposes of measuring or estimating the video quality perceived by users, in the last decade various models have been proposed and there have been several standardizations. The "Video Quality Experts Group" (VQEG) is an organization that was created with the goal of advance the field of video quality assessment by investigating new and advanced subjective and objective quality metrics and measurement techniques. In this paper we review the work performed by the VQEG, the progress in this area and the recently completed models for estimating video quality.El video digital, así como los contenidos multimedia, distribuidos a través de redes de telecomunicaciones, experimentan varios tipos de distorsiones o degradaciones durante el proceso de adquisición, compresión, procesamiento, transmisión y reproducción. Uno de los factores claves en el éxito de un sistema o servicio multimedia es poder lograr que la calidad de la experiencia percibida por el usuario resulte aceptable. La calidad de video es uno de los principales factores en la calidad global experimentada por los usuarios. Por tanto, para los operadores es necesario contar con herramientas que le permitan saber la clase de servicio que brindan a sus clientes. A los efectos de poder medir o estimar la calidad del video percibida, en la última década se han propuesto diversos modelos y se han realizado varias estandarizaciones. En este proceso, se destaca el trabajo del “Video Quality Experts Group” (VQEG), organismo que fue creado con el objetivo de avanzar en el campo de la evaluación de calidad de video, mediante la investigación de nuevas y avanzadas técnicas y métodos de evaluación, tanto subjetivas como objetivas. En el presente trabajo se realiza una revisión del trabajo del VQEG y de los avances y estandarizaciones recientemente realizadas en modelos de estimación de calidad de video

2005 año internacional de la física: 100 años de los artículos de 1905 de Albert Einstein y 80 años de su visita a Montevideo

El año 2005 ha sido declarado por la Asamblea General de las Naciones Unidas como Año Internacional de la Física.El texto de la declaración destaca en primer lugar la importancia de la Física en el avance de la comprensión de la naturaleza y de los avances tecnológicos