I/Q imbalance in two-way AF relaying: Power allocation and performance analysis

We investigate the performance of dual-hop two-way amplify-and-forward (AF) relaying in the presence of inphase and quadrature-phase imbalance (IQI) at the relay node. In particular, the effective signal-to-interference-plus-noise ratio (SINR) at both sources is derived. These SINRs are used to design an instantaneous power allocation scheme, which maximizes the minimum SINR of the two sources under a total transmit power constraint. The solution to this optimization problem is analytically determined and used to evaluate the outage probability (OP) of the considered two-way AF relaying system. Both analytical and numerical results show that IQI can create fundamental performance limits on two-way relaying, which cannot be avoided by simply improving the channel conditions.

Short-term wind power forecast based on cluster analysis and artificial neural networks

[EN]In this paper an architecture for an estimator of short-term wind farm power is proposed. The estimator is made up of a Linear Machine classifier and a set of k Multilayer Perceptrons, training each one for a specific subspace of the input space. The splitting of the input dataset into the k clusters is done using a k-means technique, obtaining the equivalent Linear Machine classifier from the cluster centroids...

Power relations and good governance: a social network analysis of the evolution of the integrity in public office act in the Commonwealth of Dominica

La Banque mondiale propose la bonne gouvernance comme la stratégie visant à corriger les maux de la mauvaise gouvernance et de faciliter le développement dans les pays en développement (Carayannis, Pirzadeh, Popescu & 2012; & Hilyard Wilks 1998; Leftwich 1993; Banque mondiale, 1989). Dans cette perspective, la réforme institutionnelle et une arène de la politique publique plus inclusive sont deux stratégies critiques qui visent à établir la bonne gouvernance, selon la Banque et d’autres institutions de Bretton Woods. Le problème, c’est que beaucoup de ces pays en voie de développement ne possèdent pas l’architecture institutionnelle préalable à ces nouvelles mesures. Cette thèse étudie et explique comment un état en voie de développement, le Commonwealth de la Dominique, s’est lancé dans un projet de loi visant l’intégrité dans la fonction publique. Cette loi, la Loi sur l’intégrité dans la fonction publique (IPO) a été adoptée en 2003 et mis en œuvre en 2008. Cette thèse analyse les relations de pouvoir entre les acteurs dominants autour de évolution de la loi et donc, elle emploie une combinaison de technique de l’analyse des réseaux sociaux et de la recherche qualitative pour répondre à la question principale: Pourquoi l’État a-t-il développé et mis en œuvre la conception actuelle de la IPO (2003)? Cette question est d’autant plus significative quand nous considérons que contrairement à la recherche existante sur le sujet, l’IPO dominiquaise diverge considérablement dans la structure du l’IPO type idéal. Nous affirmons que les acteurs "rationnels," conscients de leur position structurelle dans un réseau d’acteurs, ont utilisé leurs ressources de pouvoir pour façonner l’institution afin qu’elle serve leurs intérêts et ceux et leurs alliés. De plus, nous émettons l’hypothèse que: d’abord, le choix d’une agence spécialisée contre la corruption et la conception ultérieure de cette institution reflètent les préférences des acteurs dominants qui ont participé à la création de ladite institution et la seconde, notre hypothèse rivale, les caractéristiques des modèles alternatifs d’institutions de l’intégrité publique sont celles des acteurs non dominants. Nos résultats sont mitigés. Le jeu de pouvoir a été limité à un petit groupe d’acteurs dominants qui ont cherché à utiliser la création de la loi pour assurer leur légitimité et la survie politique. Sans surprise, aucun acteur n’a avancé un modèle alternatif. Nous avons conclu donc que la loi est la conséquence d’un jeu de pouvoir partisan. Cette recherche répond à la pénurie de recherche sur la conception des institutions de l’intégrité publique, qui semblent privilégier en grande partie un biais organisationnel et structurel. De plus, en étudiant le sujet du point de vue des relations de pouvoir (le pouvoir, lui-même, vu sous l’angle actanciel et structurel), la thèse apporte de la rigueur conceptuelle, méthodologique, et analytique au discours sur la création de ces institutions par l’étude de leur genèse des perspectives tant actancielles que structurelles. En outre, les résultats renforcent notre capacité de prédire quand et avec quelle intensité un acteur déploierait ses ressources de pouvoir.

Concentrating solar power + desalination plants (CSP+D): models and performance analysis

Tese submetida à Universidade de Lisboa, Instituto Superior Técnico e aprovada em provas públicas para a obtenção do Grau de Doutor em Sistemas Sustentáveis de Energia.

Mathematical analysis of maximum power generated by photovoltaic systems and fitting curves for standard test conditions

The rural electrification is characterized by geographical dispersion of the population, low consumption, high investment by consumers and high cost. Moreover, solar radiation constitutes an inexhaustible source of energy and in its conversion into electricity photovoltaic panels are used. In this study, equations were adjusted to field conditions presented by the manufacturer for current and power of small photovoltaic systems. The mathematical analysis was performed on the photovoltaic rural system I- 100 from ISOFOTON, with power 300 Wp, located at the Experimental Farm Lageado of FCA/UNESP. For the development of such equations, the circuitry of photovoltaic cells has been studied to apply iterative numerical methods for the determination of electrical parameters and possible errors in the appropriate equations in the literature to reality. Therefore, a simulation of a photovoltaic panel was proposed through mathematical equations that were adjusted according to the data of local radiation. The results have presented equations that provide real answers to the user and may assist in the design of these systems, once calculated that the maximum power limit ensures a supply of energy generated. This real sizing helps establishing the possible applications of solar energy to the rural producer and informing the real possibilities of generating electricity from the sun.

An Analysis of Colombian Power Market Price Behavior from an Industrial Organization Perspective

We analyze the behavior of spot prices in the Colombian wholesale power market, using a series of models derived from industrial organization theory -- We first create a Cournot-based model that simulates the strategic behavior of the market-leader power generators, which we use to estimate two industrial organization variables, the Index of Residual Demand and the Herfindahl-Hirschman Index (HHI) -- We use these variables to create VAR models that estimate spot prices and power market impulse-response relationships -- The results from these models show that hydroelectric generators can use their water storage capability strategically to affect off-peak prices primarily, while the thermal generators can manage their capacity strategically to affect on-peak prices -- In addition, shocks to the Index of Residual Capacity and to the HHI cause spot price fluctuations, which can be interpreted as the generators´ strategic response to these shocks

Impact analysis study in a typical solar PV microgrid power system

Microgrid (MG) power system with Distributed Generation (DG) plays an important role to provide reliable, secure, and low carbon emission energy supply for communities, in case of any failure or disturbance of energy supply from the main grid. At the same time, DG also contributes to several technical issues in the MG distribution network. Power quality (PQ) issues are one of the main technical challenges when integrating Renewable Energy (RE) sources in MG network. In this paper, the PQ issues like; power variation, voltage deviation, and Total Harmonic Distortion (THD) have been addressed by an impact analysis study on a typical solar PV MG power system in both on-grid and off-grid mode of operation. Analysis results from the study will be helpful in developing an independent MG power system with improved PQ conditions.

Maximum power point tracking techniques for photovoltaic systems: a comprehensive review and comparative analysis

Maximum Power Point Tracking (MPPT) is an important concern in Photovoltaic (PV) systems. As PV systems have a high cost of energy it is essential that they are operated to extract the maximum possible power at all times. However, under non-uniform environmental conditions, which frequently arise in the outdoor environment, many MPPT techniques will fail to track the global peak power. This review paper discusses conventional MPPT techniques designed to operate under uniform environmental conditions and highlights why these techniques fail under non-uniform conditions. Following this, techniques designed specifically to operate under non-uniform environmental conditions are analysed and compared. Simulation results which compare the performance of the common Perturb and Observe (P&O) method, the Particle Swarm Optimisation (PSO) and the Simulated Annealing (SA) MPPT approaches under non-uniform environmental conditions are also presented. The research presented in this review indicates that there is no single technique which can achieve reliable global MPPT with low cost and complexity and be easily adapted to different PV systems.

A Cost Analysis Of Carbon Dioxide Emission Reduction Strategies For New Plants In Michigan's Electric Power Sector

This thesis attempts to find the least-cost strategy to reduce CO2 emission by replacing coal by other energy sources for electricity generation in the context of the proposed EPA’s regulation on CO2 emissions from existing coal-fired power plants. An ARIMA model is built to forecast coal consumption for electricity generation and its CO2 emissions in Michigan from 2016 to 2020. CO2 emission reduction costs are calculated under three emission reduction scenarios- reduction to 17%, 30% and 50% below the 2005 emission level. The impacts of Production Tax Credit (PTC) and the intermittency of renewable energy are also discussed. The results indicate that in most cases natural gas will be the best alternative to coal for electricity generation to realize CO2 reduction goals; if the PTC for wind power will continue after 2015, a natural gas and wind combination approach could be the best strategy based on the least-cost criterion.

Analysis of Transmission System Adequacy Considering the Constrained Fuzzy Power Flow

Power flow calculations are one of the most important tools for power system planning and operation. The need to account for uncertainties when performing power flow studies led, among others methods, to the development of the fuzzy power flow (FPF). This kind of models is especially interesting when a scarcity of information exists, which is a common situation in liberalized power systems (where generation and commercialization of electricity are market activities). In this framework, the symmetric/constrained fuzzy power flow (SFPF/CFPF) was proposed in order to avoid some of the problems of the original FPF model. The SFPF/CFPF models are suitable to quantify the adequacy of transmission network to satisfy “reasonable demands for the transmission of electricity” as defined, for instance, in the European Directive 2009/72/EC. In this work it is illustrated how the SFPF/CFPF may be used to evaluate the impact on the adequacy of a transmission system originated by specific investments on new network elements

Average-case analysis of power consumption in embedded systems

Power efficiency is one of the most important constraints in the design of embedded systems since such systems are generally driven by batteries with limited energy budget or restricted power supply. In every embedded system, there are one or more processor cores to run the software and interact with the other hardware components of the system. The power consumption of the processor core(s) has an important impact on the total power dissipated in the system. Hence, the processor power optimization is crucial in satisfying the power consumption constraints, and developing low-power embedded systems. A key aspect of research in processor power optimization and management is “power estimation”. Having a fast and accurate method for processor power estimation at design time helps the designer to explore a large space of design possibilities, to make the optimal choices for developing a power efficient processor. Likewise, understanding the processor power dissipation behaviour of a specific software/application is the key for choosing appropriate algorithms in order to write power efficient software. Simulation-based methods for measuring the processor power achieve very high accuracy, but are available only late in the design process, and are often quite slow. Therefore, the need has arisen for faster, higher-level power prediction methods that allow the system designer to explore many alternatives for developing powerefficient hardware and software. The aim of this thesis is to present fast and high-level power models for the prediction of processor power consumption. Power predictability in this work is achieved in two ways: first, using a design method to develop power predictable circuits; second, analysing the power of the functions in the code which repeat during execution, then building the power model based on average number of repetitions. In the first case, a design method called Asynchronous Charge Sharing Logic (ACSL) is used to implement the Arithmetic Logic Unit (ALU) for the 8051 microcontroller. The ACSL circuits are power predictable due to the independency of their power consumption to the input data. Based on this property, a fast prediction method is presented to estimate the power of ALU by analysing the software program, and extracting the number of ALU-related instructions. This method achieves less than 1% error in power estimation and more than 100 times speedup in comparison to conventional simulation-based methods. In the second case, an average-case processor energy model is developed for the Insertion sort algorithm based on the number of comparisons that take place in the execution of the algorithm. The average number of comparisons is calculated using a high level methodology called MOdular Quantitative Analysis (MOQA). The parameters of the energy model are measured for the LEON3 processor core, but the model is general and can be used for any processor. The model has been validated through the power measurement experiments, and offers high accuracy and orders of magnitude speedup over the simulation-based method.

C-reactive protein concentrations across the mood spectrum in bipolar disorder: a systematic review and meta-analysis

BACKGROUND: Inflammatory processes and neural-immune interactions have been implicated in the pathogenesis of psychiatric conditions, but studies in bipolar disorder are inconclusive so far. We aimed to investigate whether peripheral concentrations of C-reactive protein (CRP), an acute-phase response protein of inflammatory activity, are increased in bipolar disorder across the mood spectrum. METHODS: In this systematic review and meta-analysis, we searched MEDLINE, the Cochrane Library, Scopus, and Web of Knowledge from database inception to Aug 14, 2016, for studies that measured serum and plasma CRP concentrations in adult patients with bipolar disorder (as defined by DSM-IV-TR) and healthy controls. We extracted data from published reports. We did three between-group meta-analyses comparing CRP concentrations in patients in mania, depression, or euthymia, with those in healthy controls (cross-sectional studies), and two within-group meta-analyses comparing changes in CRP concentrations before and after treatment of an index manic or depressive episode (longitudinal studies). We used Hedges' adjusted g to calculate effect sizes and pooled results using random-effect models. We also did meta-regression analyses by mood state to investigate possible moderators of CRP concentrations. FINDINGS: We identified 27 studies representing 2161 patients with bipolar disorder and 81 932 healthy controls. Compared with healthy individuals, CRP concentrations were moderately increased in people with bipolar disorder during depression (g 0·67, 95% CI 0·23 to 1·11; p=0·003) and euthymia (0·65, 0·40 to 0·90; p<0·0001) and more substantially increased during mania (0·87, 0·58 to 1·15; p<0·0001). The extent of the increases in CRP concentrations in mania and depression was not related to symptom severity (p=0·256 for mania and p=0·626 for depression). CRP concentrations were moderately decreased after resolution of an index manic episode (-0·36, -0·66 to -0·05; p=0·022) and slightly decreased after resolution of an index depressive episode (-0·18, -0·30 to -0·07; p=0·002). INTERPRETATION: CRP concentrations are increased in bipolar disorder regardless of mood state, but are higher during mania than in depression and euthymia, suggesting an increased inflammatory burden in mania.