Cálculo de impedancia característica de líneas de cinta usando compresión espacial, diferencias finitas y algoritmos genéticos

In this paper we computed the characteristic impedance of homogeneous Striplines with finite or infinite dielectric substrate, using the Finite Differences Method (FDM) and Spatial Compression (CE), with transformation functions found through Genetics Algorithms (GAs). The CE consist on the transformation of any plane transmission line domain with very different dimensions, in a rectangle in which the images of the dimensions maintain proportions that make easier the FDM application in an efficient way, without supposing that the dielectric substrate is infinite. The coefficients of the transformation were found using GAs. We obtained Characteristic Impedance values for lines with different relations of dimensions and for finite or infinite dielectric substrates. The results were compared with results found in the literature, obtaining good agreement

Performance Analysis of Space-Time Block Codes in Flat Fading MIMO Channels with Offsets

We consider the effect of imperfect carrier offset compensation on the performance of space-time block codes. The symbol error rate (SER) for orthogonal space-time block code (OSTBC) is derived here by taking into account the carrier offset and the resulting imperfect channel state information (CSI) in Rayleigh flat fading MIMO wireless channels with offsets.https://doi.org/10.1155/2007/3054

DISEÑO DE UN SISTEMA CEMENTANTE PARA POZOS UTILIZADOS EN ANCLAJE DE PLATAFORMAS DE PRODUCCIÓN EN AGUAS PROFUNDAS. CASO: RIO DE JANEIRO, BRASIL / Cement System Design used in Anchorage Wells for Offshore Deepwater Production Platforms. Event: Rio de Janeir

La cementación de pozos en zonas no consolidadas, con estrecho margen entre los gradientes de poro y fractura, requierenun foco en sistemas cementantes de baja densidad. La perforación en aguas profundas donde una serie de pozos sonperforados, cementados, completados y puestos a producción a una plataforma específica, la cual posee un determinadonúmero de anclas que de acuerdo con el estudio de suelos puede ser del tipo torpedo o de anclaje utilizando pozoscementados. Estos pozos utilizados para el anclaje de unidades marítimas de producción se perforan en aguas profundascon retorno al suelo marino, sin equipamiento para prevenir reventones y sin tubería de conexión entre la unidad marítimade perforación y el pozo, en zonas no consolidadas con bajo gradiente de fractura. Diseños de sistemas cementantesson desarrollados y pruebas de laboratorio son ejecutadas para determinar si se adaptan a las condiciones previstas paragarantizar el anclaje mediante un eficiente sistema de pozo, cemento y tubería. Se desarrollaron sistemas cementantes paraaplicación Costa Afuera con una resistencia compresiva mayor a 2500 psi, que estén entre los rangos de gradiente de poroy de fractura en formaciones no-consolidadas, en profundidad de agua de 1400 m y temperatura del suelo marino de 40ºF. Es novedoso el desarrollo de sistemas cementantes en láminas de agua profundas, con temperaturas del suelo marinorelativamente bajas y con una alta resistencia compresiva.ABSTRACTThe cementing of wells in unconsolidated zones, with narrow margin between the pore and fracture gradients, requirea focus on low density cements systems. Drilling en deep water where a series of wells are drilled, cemented, completeand put into a production in a specific maritime unit. These maritime unit of production would need a certain number ofanchors, which according to study of soils can be of torpedo type or cemented wells. When drilling deep water wells ofthe sea floor return, the riserless, drill sections have low fracture gradient, unconsolidated sands. Cement system designare developed and laboratory tests are executed to determine the anchorage which an efficient system of well, cement andcasing. Cement systems developed for offshore application with a compressive strength greater than 2500 psi, betweenthe gradient pore and fracture in unconsolidated formations, in water depth of 1400 m, where the temperature of the oceanfloor is 40 ºF. The cement system development is new in deep water, with low temperatures of the sea floor and with a highcompressive strength.Keywords: Well cementation for anchorage, Light cement, Platforms anchorage, Superficial casing, microspheres

Haematological characteristics of freshwater-reared and wild mullet, Mugil platanus Günther (Osteichthyes, Mugilidae)

Mullets, Mugilplalanus Günther, 1880. were obtained from the estua-rine area of CananÉia (São Paulo, Brazil) and from freshwater tearing tanks. For each fish the body weight, body length, gonad weight and gonad maturation stage were recorded and the allometric index (K) was calculated. Blood was collected for hematocrit (Ht), hemoglobin level (lib), total cell count (Er), and the determination of hematological indices (MCV. MCH, MCHC), as well as the differential leukocyte count (lymphocytes, monocytes, neutrophils, basophils and '"other cells"). The averages of the hematological analyses, hematological indeces, condition factor and leukocytes percentage of the specimens acclimated to fresh water were significantly higher than those of the specimens from the estuary