Full-Duplex Relaying in MIMO-OFDM Frequency-Selective Channels with Optimal Adaptive Filtering

In-band full-duplex transmission allows a relay station to theoretically double its spectral efficiency by simultaneously receiving and transmitting in the same frequency band, when compared to the traditional half-duplex or out-of-band full-duplex counterpart. Consequently, the induced self-interference suffered by the relay may reach considerable power levels, which decreases the signal-to-interference-plus-noise ratio (SINR) in a decode-and-forward (DF) relay, leading to a degradation of the relay performance. This paper presents a technique to cope with the problem of self-interference in broadband multiple-input multiple-output (MIMO) relays. The proposed method uses a time-domain cancellation in a DF relay, where a replica of the interfering signal is created with the help of a recursive least squares (RLS) algorithm that estimates the interference frequency-selective channel. Its convergence mean time is shown to be negligible by simulation results, when compared to the length of a typical orthogonal-frequency division multiplexing (OFDM) sequences. Moreover, the bit-error-rate (BER) and the SINR in a OFDM transmission are evaluated, confirming that the proposed method extends significantly the range of self-interference power to which the relay is resilient to, when compared with other mitigation schemes

A 3D generalized rigid particle contact model for rock fracture

Detailed rigid particle models have been proposed for modeling fracture in quasibrittle materials. The rigid particle circular models proposed in the literature do not properly reproduce the known rock friction angle and the observed rock tensile strength to compression strength ratio. In this article, a 3D rigid particle contact model, 3D-GCM, is presented which has been developed to study fracture phenomena in rock. The 3D-GCM contact model incorporates in a straightforward manner the force versus displacement relationships of the traditional contact point contact model model, PCM. Furthermore it provides both moment transmission and simple physical constitutive models based on standard force displacement relationships. The 3D-GCM model is validated against known triaxial and Brazilian tests of a granite rock. It is shown that the enhanced rigid particle model leads to a better agreement with the experimental results

Massive MIMO Full-Duplex Relaying with Optimal Power Allocation for Independent Multipairs

With the help of an in-band full-duplex relay station, it is possible to simultaneously transmit and receive signals from multiple users. The performance of such system can be greatly increased when the relay station is equipped with a large number of antennas on both transmitter and receiver sides. In this paper, we exploit the use of massive arrays to effectively suppress the loopback interference (LI) of a decode-and-forward relay (DF) and evaluate the performance of the end-to-end (e2e) transmission. This paper assumes imperfect channel state information is available at the relay and designs a minimum mean-square error (MMSE) filter to mitigate the interference. Subsequently, we adopt zero-forcing (ZF) filters for both detection and beamforming. The performance of such system is evaluated in terms of bit error rate (BER) at both relay and destinations, and an optimal choice for the transmission power at the relay is shown. We then propose a complexity efficient optimal power allocation (OPA) algorithm that, using the channel statistics, computes the minimum power that satisfies the rate constraints of each pair. The results obtained via simulation show that when both MMSE filtering and OPA method are used, better values for the energy efficiency are attained.Comment: Accepted to the 16th IEEE International Workshop on Signal Processing Advances in Wireless Communications - SPAWC, Stockholm, Sweden 201

Full-duplex massive MIMO with physical layer network coding for the two-way relay channel

The role of interference in wireless networks has recently been profoundly re-thought with the emergence of new techniques for combating it and exploit it to maximize the use efficiency of the physical resources. This paper presents a two-way relay channel using a lattice-based physical layer network coding scheme, a massive MIMO array, and in-band full-duplex, taking into account the residual self-interference that results after applying recently developed cancellation techniques for the loopback interference. The proposed scheme is able to ultimately exchange information across the TWRC in only one time slot, whereas four time slots would be needed in a conventional TWRC. The system's performance is shown to be mostly dependent on the number of antennas at the relay, and also dependent on the channel state information of all the channel matrices, including the one describing the loopback interference at the relay. For base-stations and relays with a few hundred antennas, the proposed scheme is feasible for wireless systems.info:eu-repo/semantics/acceptedVersio

Poderemos encontrar factores preditivos de vómitos no pós-operatório de cirurgia em regime de ambulatório?

Abstract A retrospective analyses of patients submitted to surgery on a day basis was made through our database. The goal of the study was to identify risk factors of postoperative vomiting associated to day surgery. 2115 patients operated between January 2003 and November 2004 on our day surgery unit were included. 70 patients (3,3%) suffered at least on episode of postoperative vomiting. Several factors were analysed: age, sex, surgical speciality, ASA physical status, anaesthetic technique and the duration of anesthesia. Chi-Square Test was used for testing each factor individually. Differences were considered significant when p <0,05. Logistic regression was then used to identify the multivariate association strength of these factors. The female sex (Odds ratio =4,94) and the duration of anesthesia when longer than 180 minutes (Odds ratio =8,13), had been associated to a higher incidence of postoperative vomiting, while loco-regional technique (Odds ratio = 0,15) and sedation with local anaesthesia (Odds ratio =0,09) had been associated with a lower incidence. Authors evidence the importance of the identification of postoperative vomiting risk factors that will allow us to establish better guidelines on postoperative nausea and vomiting prophylaxis in these patients and to improve the quality of our clinical care and the satisfaction of our patients. Através da análise do registo informatizado de dados dos doentes operados em regime de ambulatório, os autores procuraram identificar factores de risco que se encontrassem associados a uma maior incidência de vómitos no pós-operatório (VPO). Incluíram-se 2115 doentes submetidos a cirurgia entre Janeiro de 2003 e Novembro de 2004, tendo 70 doentes sofrido pelo menos um episódio de VPO (3,3%). Foram consideradas variáveis a analisar, a idade, o sexo, a especialidade cirúrgica, o estado físico (ASA), a técnica anestésica e a duração da anestesia. Procedeu-se à análise estatística de cada factor individualmente através da aplicação do χ2, seguindo-se a utilização de uma regressão logística para identificar a força de associação multivariável desses factores. O sexo feminino (Odds ratio =4,94) e a duração da anestesia quando superior a 180 minutos (OR =8,13), associaram-se a uma maior incidência de VPO enquanto a técnica loco-regional (OR =0,15) e a sedação com anestesia local (OR =0,09) se associaram a uma menor incidência daqueles. Os autores evidenciam a importância deste tipo de trabalhos na identificação de factores de risco que possam levar à criação de escalas de risco que orientem com maior racionalidade económica, a intervenção terapêutica profiláctica das náuseas e vómitos no pós-operatório

Derivative Instruments on Emission Allowances: factors Influencing Disclosure in Portuguese Companies

Purpose: This article aims to analyze the degree of disclosure of information on Derivative instruments on Emission Allowances, analyzing the degree of compliance with the underlying accounting regulations, and their determinants factors.   Theoretical framework: With the evolution of the European Union Emission Trading System (EU ETS), which foresees that the emission licenses will no longer be allocated free of charge and will be negotiated at auction, it is expected that there will be an increase in the trading of derivative instruments on licenses, to cover any risks of future price fluctuations, and therefore an increase in disclosure in this area.   Design/methodology/approach: The methodology used in this study was the content analysis of the Reports and Accounts of the sample entities over a 12-year period, based on the creation of disclosure indexes for the topics under analysis. This is a longitudinal study that seeks to address possible changes in the behavior of companies' reporting practices in the periods 2008-2102 and 2013-2020 (corresponding to the 2nd and 3rd phases of the EU ETS).   Findings: The results of the derivative disclosure index, in general, is higher (average IDGD is 0.81), although it is still very low when it specifically refers to derivative instruments for risk hedging related to emission licenses (IDL_LE = 0.11). Contrary to expectations, not only companies do not use this type of instrument to cover the risk of fluctuations in the price of licenses, nor is the change in the behavior of companies between the 2nd and 3rd EU ETS periods significant. Regarding the explanatory factors studied, there is only a statistically positive correlation between the disclosure index and profitability.   Research, Practical &amp; Social implications: The study will focus on a sample of companies operating in Portugal, which are part of the National Emission Licensing Plan (PNALE) I and II. The literature is silent on previous studies related to disclosure on emission allowances derivatives, so our study represents a contribution to the advancement of literature in this area.   Originality/value:  As far as we know, previous studies related to the disclosure of derivative instruments for gas emission licenses are non-existent, so our study represents a contribution to the advancement of the literature in this area

De alfabetizandas a alfabetizadoras : nuances da construção dessa trajetória

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Secagem de banana (var. prata) em campo de micro-ondas com vácuo contínuo ou intermitente

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia de Alimentos, Florianópolis, 2014.Realizou-se um estudo comparativo de diferentes estratégias de secagem para obtenção de bananas desidratadas com microestrutura e propriedades de textura controladas. Este trabalho avaliou a influência da aplicação de pulsos de vácuo nas propriedades físicas que controlam a crocância de frutas desidratadas em campo de micro-ondas. Adaptou-se um forno de micro-ondas doméstico que permitiu utilizar vácuo juntamente com o sistema rotativo, que homogeniza a distribuição das ondas eletromagnéticas. No interior do forno foi utilizado um recipiente de polipropileno (câmara de vácuo) conectado a uma bomba de vácuo. Fatias de banana (var. Prata) de 5 mm de espessura foram desidratadas pela secagem com: I) micro-ondas a vácuo (MV) e II) múltiplos ciclos de aquecimento-pulso de vácuo, associados a um período complementar de secagem por micro-ondas sob vácuo (MVMFD). Ambos os procedimentos de secagem foram testados com potência nominal do forno de micro-ondas de 400, 700 e 1000 W. Na secagem MVMFD as amostras foram aquecidas no campo de micro-ondas até aproximadamente 60 °C, quando desligou-se o gerador de micro-ondas e foi reduzida a pressão da câmara até valores próximos a 8,0 kPa, seguido por rápida pressurização do sistema até a pressão atmosférica (pulso de vácuo). Este procedimento foi repetido por mais duas vezes. As cinéticas de secagem por MV e MVMFD apresentaram 3 períodos de secagem bem definidos, período de aquecimento, período de secagem rápida (taxa constante) e período de taxa decrescente de secagem. Entre os modelos empíricos utilizados, o modelo de Page foi o que melhor se ajustou a secagem de banana. O aumento de potência do micro-ondas ocasiona a diminuição do tempo de secagem. Com relação à textura, microestrutura, densidade aparente e porosidade não houve diferença das mesmas com relação a alteração da potência, quando comparado o mesmo processo. A potência de 1000 W apresentou menor tempo de processo e os parâmetros de cor foram mais preservados, tornando esta condição interessante para a secagem da banana. As diferenças estruturais das amostras secas pelos diferentes processos foram verificadas pela análise de microscopia eletrônica de varredura. As micrografias mostraram a formação de poros maiores nas amostras MVMFD, quando comparado com o processo de MV, além de maior porosidade (20% a 34% maior) e menor densidade aparente. Isso implicou em maior irregularidade na curva de força x penetração (maior número de picos) das amostras secas por MVMFD, obtida no teste de penetração, indicando maior crocância do produto final. O processoMVMFD é competitivo com o processo de liofilização para a produção de frutas desidratadas crocantes, pois apresentou frutas com umidade, atividade de água e propriedades mecânicas semelhantes às observadas para frutas liofilizadas comerciais, com uma redução de 99% no tempo de processo. Os resultados obtidos mostram que é possível controlar a textura das frutas desidratadas através da aplicação de múltiplos ciclos de aquecimento-pulso de vácuo, em campo de micro-ondas. Deste modo, este trabalho apresenta resultados que podem ser de grande utilidade para o aproveitamento industrial e agregação de valor às bananas.Abstract : A comparative study was realized of different strategies for drying to obtain dehydrated bananas with microstructure and texture properties controlled. This study evaluated the influence of the application of pulses of vacuum in the physical properties that control the crispness of dried fruit in microwave field. A domestic microwave oven was adapted to allowed the use in conjunction with vacuum and rotating turntable, which homogenizes the distribution of electromagnetic waves. Inside the oven a container of polypropylene (vacuum chamber) connected to a vacuum pump was used. Banana slices (Prata var.) 5 mm thick were dehydrated by drying: I) microwave vacuum drying (MV) and II) multiple cycles of heating-vacuum pulse, associated with an additional period of microwave vacuum drying (MVMFD). Both drying procedures were tested with nominal power of microwave oven of 400, 700 and 1000 W. In MVMFD drying the samples were heated in the microwave field to approximately 60 °C, when was turned off the microwave generator and the pressure was reduced from chamber to values near 8.0 kPa, followed by rapid pressurization of system to atmospheric pressure (vacuum pulse). This procedure was repeated two more times. The kinetics of drying MVMFD and MV presented 3 drying time well-defined, heating period, period of rapid drying (constant rate) and the falling rate period of drying. Among the empirical models used, the Page model was the best fit drying of banana. The increased power of the microwave causes the reduction of drying time. Regarding the texture, microstructure, density and porosity there was no difference of the same with respect to the potency, when compared to the same process. The power of 1000 W showed less process time and color parameters were better preserved, making this condition interesting for drying banana. Structural differences of the dried samples by different processes were verified by analysis of scanning electron microscopy. Micrographs showed the formation of larger pores MVMFD the samples when compared to the process of MV, besides higher porosity (20% to 34% higher) and lower density. This resulted in greater irregularity in the force-penetration (higher number of peaks) for the dried samples MVMFD obtained in penetration test curve, indicating greater crispness of the final product. The process of MVMFD is competitive with the lyophilization process for producing crunchy dried fruit, it showed fruits with moisture, water activity and mechanical properties similar to those observed for commercial freeze dried fruit, with a 99% reduction in process time. The results show that it is possible to control the texture ofthe dried fruit by applying multiple cycles of heating-pulse vacuum in the field of microwave. Thus, this work presents results that can be useful for industrial use and aggregation value to bananas

Uso do laser cirúrgico de alta potência em lesões bucais: considerações clínicas e histopatológicas

TCC (graduação) - Universidade Federal de Santa Catarina. Centro de Ciências da Saúde. Odontologia.Desde as primeiras aplicações do LASER na Odontologia, em 1964, até os dias atuais, ocorreram muitos avanços tecnológicos que nos permitem utilizar a laserterapia com mais segurança. As indicações do uso desta tecnologia têm aumentado muito em Odontologia. O laser de baixa intensidade tem sido muito estudado em Odontologia e já estão comprovadas suas indicações e vantagens como um instrumento para tratamento de dor, redução de edema e inflamação de lesões da mucosa bucal. No entanto, a utilização do laser de alta intensidade em Odontologia ainda exige maior número de pesquisas. Os estudos publicados indicam muitas vantagens na sua utilização em situações cirúrgicas de pacientes com baixa capacidade hemostática; contrapondo-se a isto, apenas seus efeitos térmicos gerando possíveis efeitos adversos sobre os tecidos adjacentes às áreas operadas. Este trabalho objetivou avaliar a ação do laser de alta potência em lesões de tecidos moles bucais removidas cirurgicamente bem como analisar o efeito térmico sobre as margens nas lesões de tecidos moles biopsiadas afim de verificar se o comprometimento das margens interfere no diagnósitico histopatológico. A pesquisa foi realizada com 21 lesões bucais removidas de pacientes do Núcleo de Odontologia Hospitalar do Hospital Universitário/UFSC com o laser cirúrgico de alta potência do tipo diodo, no período entre janeiro de 2015 e março de 2017, incluindo pacientes de ambos os sexos e sem preferência por faixa etária ou diagnóstico clínico da lesão. Nenhuma das lesões biopsiadas a laser foi excluída da amostra. Após a localização das fichas de biópsia do Laboratório de Patologia Bucal/UFSC, foi feita a busca pelas lâminas histopatológicas geradas a partir das peças biopsiadas. Todos os cortes histológicos obtidos, seriados ou não, foram analisados através de microscópio óptico em aumentos de 50, 100 e 400x. Os danos causados pelo laser na região de cortes foram avaliados por consenso, entre autora e orientadora, tendo sido classificados em pequeno, médio e grande, de acordo com o padrão do dano predominante. A amostra foi composta por 21 pacientes, 8 do sexo masculino e 13 do sexo feminino. Do total das lesões, 57% foram classificadas hiperplasia fibrosa inflamatória, seguido de granuloma piogênico (9%), hiperplasia fibrosa focal (9%), sialoadenite (5%), neuroma encapsulado em paliçada (5%), linfangioma (5%), processo inflamatório crônico inespecífico com áreas de abscedação (5%) e fragmento de mucosa com degeneração generalizada de tecido conjuntivo (5%). Os resultados mostraram que os danos predominantes foram os classificados como “médio”, no entanto, em nenhum dos casos analisados o corte a laser inviabilizou o diagnóstico histopatológico da lesão. Houve variações de acordo com o tecido biopsiado ser mais ou menos fibroso, provavelmente devido aos ajustes necessários na potência do laser no momento da realização do procedimento, bem como da experiência do operador em realizar tal procedimento. Os dados foram organizados em planilhas do programa Microsoft Excel e a análise descritiva foi realizada. Deve-se, portanto, considerar as indicações e vantagens clínicas da utilização desta tecnologia na tomada de decisão sobre seu uso, uma vez que, se usado corretamente, tende a trazer muitos benefícios tanto ao paciente quanto ao operador. Desta forma, mais estudos clínico-histopatológicos, randomizados, são necessários para melhor avaliar os danos térmicos que ocorrem com os tecidos bucais seccionados com laser de alta potência.Since the first applications of LASER in Dentistry in 1964 to the present day, many technological advances have occurred that allow us to use laser therapy safety. The clinical indications of this technology are increasing in Dentistry. The low level laser therapy (LLLT) has been studied in dentistry and its indications and advantages are already proven as an instrument for pain control, reduction of swelling and inflammation of lesions in the oral cavity. However, the use of high level laser therapy in dentistry still requires more research.Many studies indicate the advantages of high level laser therapy in surgical procedures, especially in patients with low hemostatic capacity. Thermal damage on adjacent tissues is the greatest contraindication of this technique. This study aims to evaluate the action of high level laser therapy on oral lesions removed under this technique, as well as analyze the thermal effects of laser in the soft tissue lesions removed. The research was performed with 21 oral lesions removed from patients from Dental Service of the University Hospital of Santa Catarina Federal University with the diode surgical laser, from January 2015 to March 2017. Are included patients of both sexes and with no preference for age or clinical diagnosis of the lesion. None of the biopsied laser lesions were excluded from the sample. After the pursuit of the biopsy files from Laboratório de Patologia Bucal/UFSC, the search for the histopathological slides generated from the biopsied specimens was made. All histological sections obtained, serial or non-serial, were analyzed under optical microscopy with increments of 50, 100 and 400 times. The laser thermal damage on the histopathological slides was evaluated by consensus, between author and supervisor, and was classified as “small, medium and large damage” according to the pattern of predominant damage. The results showed that the predominant thermal damage was "medium damage". However, in none of the cases analyzed, the laser surgical incision made the histopathological diagnosis of the lesion impossible. There were variations according to whether the biopsied tissue was more or less fibrous, probably due to the necessary adjustments in laser power at the time of the procedure, as well as the operator's experience in performing such a procedure. No statistical analysis was performed, only description analysis. Therefore, it is necessary to consider the indications and clinical advantages of the use of this technology in the decision making about its use, since if used correctly; it tends to bring many benefits to both the patient and the operator. Thus, more randomized clinical and histopathological studies are needed to better understand all the histological processes that occur with buccal tissues sectioned with high level laser therapy. Therefore, it is necessary to consider the indications and clinical advantages of the use of this technology in the decision making about its use, since if used correctly, it tends to bring many benefits to both the patient and the operator