Performance evaluation of IB-DFE-based strategies for SC-FDMA systems

The aim of this paper is to propose and evaluate multi-user iterative block decision feedback equalization (IB-DFE) schemes for the uplink of single-carrier frequency-division multiple access (SC-FDMA)-based systems. It is assumed that a set of single antenna users share the same physical channel to transmit its own information to the base station, which is equipped with an antenna array. Two space-frequency multi-user IB-DFE-based processing are considered: iterative successive interference cancellation and parallel interference cancellation. In the first approach, the equalizer vectors are computed by minimizing the mean square error (MSE) of each individual user, at each subcarrier. In the second one, the equalizer matrices are obtained by minimizing the overall MSE of all users at each subcarrier. For both cases, we propose a simple yet accurate analytical approach for obtaining the performance of the discussed receivers. The proposed schemes allow an efficient user separation, with a performance close to the one given by the matched filter bound for severely time-dispersive channels, with only a few iterations

A arte atlântica do Crastoeiro (Norte de Portugal) : contextos e significados

Basados en los resultados de las excavaciones arqueológicas realizadas en los complejos I y II del arte atlántico de Crastoeiro, localizados en el Monte de la Senhora da Graça y partiendo del supuesto de que los individuos no sólo viven en un espacio sino que también están inmersos o incorporados en el, este trabajo tiene como objetivo establecer algunas interpretaciones no sólo sobre la biografía de cada uno de estos loci, sino también, entender los diferentes procesos de interacción de las comunidades locales con el Monte da Senhora da Graça, especialmente aquellos que se relacionan con la elección, la construcción, la frecuencia y las acciones inherentes al uso de estos lugares que designamos arte rupestre

Slot antenna design for a wirelessly powered implantable microcooler for neuronal applications

Implantable medical devices are becoming smaller by the day, with more efficient electronics and smaller power demands. Nevertheless, there are some applications in which power demands are inherently high, and solutions must be found in order to keep the devices as small as possible. In this paper, we propose an antenna to be used in wirelessly powering a focal brain cooling implant based on a Peltier device. This antenna is designed in order to act as a heatsink for the device with the goal of minimizing its final volume, therefore design constrains such as size limitations and geometry restrictions are considered.This work is supported by FCT with the reference project PTDC/EEI-TEL/5250/2014, by FEDER funds through Projecto 3599 - Promover a Producao Cientifica e Desenvolvimento Tecnologico e a Constituicao de Redes Tematicas (3599-PPCDT).info:eu-repo/semantics/publishedVersio

Closed-loop control strategy with improved current for a flashing ratchet

We show how to switch on and off the ratchet potential of a collective Brownian motor, depending only on the position of the particles, in order to attain a current higher than or at least equal to that induced by any periodic flashing. Maximization of instant velocity turns out to be the optimal protocol for one particle but is nevertheless defeated by a periodic switching when a sufficiently large ensemble of particles is considered. The protocol presented in this article, although not the optimal one, yields approximately the same current as the optimal protocol for one particle and as the optimal periodic switching for an infinite number of them.Comment: 4 pages, 4 figure

Comparative study of inner shelf sediments (Plio-Pleistocene and present day cover) in the Western Portuguese margin

A comparative study between Pliocene-Pleistocene and present day inner shelf deposits, considering both grain-size distribution and the present day hydrodynamic conditions, at west Portuguese Coastal Margin, is conducted. The modal grain-size analysis indicates that the west Portuguese Plio-Pleistocene inner shelf sediments are made of a mixture of several populations. The coarser populations (mode >0.5 mm, 1empty set) result from reworking of previous shoreface and beach deposits after storm events or are related with transgressive ravinement lags. The intermediate population, with modes around 0.125 to 0.250 mm (3 to 2empty set), should be in equilibrium with the hydrodynamic storm conditions in the inner shelf. This population is also the main constituent of the present day inner shelf cover between 10 and 25 meters depth. The finer population, with modes around 32 mu m (5empty set), is probably deposited from suspension during fair-weather periods. Under the high hydrodynamic winter storm conditions this population remains in suspension and tends to be mobilized to outer shelf locations by downward currents. It is expected that the mud size population proportion in bulk sediment should increases basinward, but this proportion may as well be influenced by post-depositional processes in ancient deposits

Contributions to the biography of a place : the tomb 1 of the Campo de Caparinho in the microregional context:

Publicam-se os resultados dos trabalhos de escavação, realizados em Setembro de 2003, numa estrutura tumular neolítica de Campo de Caparinho, freguesia de Vilar de Perdizes, concelho de Montalegre. A escavação deste monumento tornou-se particularmente importante, quer pelas suas especificidades arquitectónicas que traduzem integração de elementos geomorfológicos pré-existentes, quer pelo facto de ter permitido comprovar a existência de estruturas tumulares em área de importantes gravuras rupestres. Partindo do princípio de que estas construções e as acções que lhe são inerentes são actuantes na criação e na manutenção da identidade grupal e da memória, discute-se o seu papel social no contexto de Campo de Caparinho, um lugar de grande significação símbólica desde o Neolítico até à Idade do Bronze.This article discusses the results of the diggings of a pre-historic tomb surveyed in September 2003. They lie within the archaeological group at Campo de Caparinho in the parish of Vilar de Perdizes, municipality of Montalegre. This tomb is located in an area containing important archaeological remains, in which there are also rock engravings and several places where ceramic and stone artefacts have been found, all of which can generally be dated between the Neolithic and the Bronze Age. The importance of this tomb is related with the geomorphology context, its architectonic particularities and with the evidence of human actions related with fire, with different rocks and, eventually, with water. Assuming that these buildings and the actions that are inherent are working in the development and maintenance of group identity and memory, it discusses its social role in the context of Caparinho, a place of great symbolic significance since the Neolithic to the Bronze Age.Núcleo de Arqueologia da Universidade do Minho (NARQ) financiado no âmbito do Contrato Plurianual com a FCT;Câmara Municipal de Montalegre

Sondagens arqueológicas no Monte da Ola, Vila Fria, Viana do Castelo (Norte de Portugal)

Este trabalho dá a conhecer os resultados das prospecções e das sondagens arqueológicas realizadas no Monte da Ola, Vila Fria, Viana do Castelo. Foi possível identificar a existência de uma necrópole de cistas no local atribuível, provavelmente, aos inícios do Bronze Final.This article draws upon the recent archaeological excavations at the site of Monte da Ola (Viana do Castelo). This site was disturbed by urban development from 1920’s. Then earthworks uncovered important archaeological finds, which are kept in the Museu Municipal de Viana do Castelo. The excavations, integrated in the project The Entre-Douro-e-Minho landscape since middle of III to the end of II millenium BC, corroborated the existence of a cemetery dating to the Bronze Age