Adaption of schottel instream turbines for river-applications

In the present thesis paper today‟s state of the art of River Hydrokinetic Energy as a potential emerging renewable source of energy is presented as well as challenges regarding the establishment of the technology. River resources have been analyzed investigating flow data of over 15 Brazilian rivers and an analytical method which categorizes a river‟s flow regime been developed. Several CFD-Simulations have been carried out to conceptualize a 1-MW River Hydrokinetic Power Plant in the Amazon, Brazil. The case study revealed that there exist river sites which from a resource perspective allow a commercial operation of hydrokinetic energy extraction devices at market competitive costs.No presente trabalho é apresentado o estado da arte do aproveitamento da Energia Hidrocinética de Rios, assim como os desafios para o uso desta tecnologia. Foram analisados os recursos fluviais de mais de quinze rios brasileiros, para então desenvolver um método analítico de categorização do regime de fluxo destes. Diversas simulacoes em CFD foram realizadas para conceitualizar uma Usina de Aproveitamento Hidrocinético de 1 MW no rio Amazonas, Brasil. O estudo de caso revelou que existem lugares do rio com recursos para operacionalizar comercialmente este tipo de aproveitamento da Energia

Likelihood Consensus and Its Application to Distributed Particle Filtering

We consider distributed state estimation in a wireless sensor network without a fusion center. Each sensor performs a global estimation task---based on the past and current measurements of all sensors---using only local processing and local communications with its neighbors. In this estimation task, the joint (all-sensors) likelihood function (JLF) plays a central role as it epitomizes the measurements of all sensors. We propose a distributed method for computing, at each sensor, an approximation of the JLF by means of consensus algorithms. This "likelihood consensus" method is applicable if the local likelihood functions of the various sensors (viewed as conditional probability density functions of the local measurements) belong to the exponential family of distributions. We then use the likelihood consensus method to implement a distributed particle filter and a distributed Gaussian particle filter. Each sensor runs a local particle filter, or a local Gaussian particle filter, that computes a global state estimate. The weight update in each local (Gaussian) particle filter employs the JLF, which is obtained through the likelihood consensus scheme. For the distributed Gaussian particle filter, the number of particles can be significantly reduced by means of an additional consensus scheme. Simulation results are presented to assess the performance of the proposed distributed particle filters for a multiple target tracking problem

Prolog to the section on wireless communications technology

The authors take a look at the existing 3G systems in service and investigate the capabilities of 4G, and while the theoretical throughput of these cellular systems is expected to be high, the future promises to offer more technological improvements and innovations.<br/

Energy efficiency of mmWave massive MIMO precoding with low-resolution DACs

With the congestion of the sub-6 GHz spectrum, the interest in massive multiple-input multiple-output (MIMO) systems operating on millimeter wave spectrum grows. In order to reduce the power consumption of such massive MIMO systems, hybrid analog/digital transceivers and application of low-resolution digital-to-analog/analog-to-digital converters have been recently proposed. In this work, we investigate the energy efficiency of quantized hybrid transmitters equipped with a fully/partially-connected phase-shifting network composed of active/passive phase-shifters and compare it to that of quantized digital precoders. We introduce a quantized single-user MIMO system model based on an additive quantization noise approximation considering realistic power consumption and loss models to evaluate the spectral and energy efficiencies of the transmit precoding methods. Simulation results show that partially-connected hybrid precoders can be more energy-efficient compared to digital precoders, while fully-connected hybrid precoders exhibit poor energy efficiency in general. Also, the topology of phase-shifting components offers an energy-spectral efficiency trade-off: active phase-shifters provide higher data rates, while passive phase-shifters maintain better energy efficiency.Comment: Published in IEEE Journal of Selected Topics in Signal Processin