Nodal price simulation in competitive electricity markets

Locational Marginal Prices (LMP) are important pricing signals for the participants of competitive electricity markets, as the effects of transmission losses and binding constraints are embedded in LMPs [1],[2]. This paper presents a software tool that evaluates the nodal marginal prices considering losses and congestion. The initial dispatch is based on all the electricity transactions negotiated in the pool and in bilateral contracts. It must be checked if the proposed initial dispatch leads to congestion problems; if a congestion situation is detected, it must be solved. An AC power flow is used to verify if there are congestion situations in the initial dispatch. Whenever congestion situations are detected, they are solved and a feasible dispatch (re-dispatch) is obtained. After solving the congestion problems, the simulator evaluates LMP. The paper presents a case study based on the the 118 IEEE bus test network.

Preservice teachers' knowledge on elementary geometry concepts

This text is based on a research, which is still in progress, whose main objective is to identify and understand what are the main difficulties of future mathematics teachers of basic education are, regarding their content knowledge in geometry in the context of the curricular unit of Geometry during their undergraduate degree. We chose a qualitative approach in the form of case study, in which data collection was done through observation, interviews, a diverse set of tasks, a diagnostic test and other documents. This paper focuses on the test given to prospective teachers at the beginning of the course. The preliminary analysis of the data points to a weak performance of preservice teachers in the test issues addressing elementary knowledge of Geometry

Drilling tool geometry evaluation for reinforced composite laminates

In this work, a comparative study on different drill point geometries and feed rate for composite laminates drilling is presented. For this goal, thrust force monitoring during drilling, hole wall roughness measurement and delamination extension assessment after drilling is accomplished. Delamination is evaluated using enhanced radiography combined with a dedicated computational platform that integrates algorithms of image processing and analysis. An experimental procedure was planned and consequences were evaluated. Results show that a cautious combination of the factors involved, like drill tip geometry or feed rate, can promote the reduction of delamination damage.

Strength improvement of adhesively-bonded joints using a reverse-bent geometry

Adhesive bonding of components has become more efficient in recent years due to the developments in adhesive technology, which has resulted in higher peel and shear strengths, and also in allowable ductility up to failure. As a result, fastening and riveting methods are being progressively replaced by adhesive bonding, allowing a big step towards stronger and lighter unions. However, single-lap bonded joints still generate substantial peel and shear stress concentrations at the overlap edges that can be harmful to the structure, especially when using brittle adhesives that do not allow plasticization in these regions. In this work, a numerical and experimental study is performed to evaluate the feasibility of bending the adherends at the ends of the overlap for the strength improvement of single-lap aluminium joints bonded with a brittle and a ductile adhesive. Different combinations of joint eccentricity were tested, including absence of eccentricity, allowing the optimization of the joint. A Finite Element stress and failure analysis in ABAQUS® was also carried out to provide a better understanding of the bent configuration. Results showed a major advantage of using the proposed modification for the brittle adhesive, but the joints with the ductile adhesive were not much affected by the bending technique.

Preservice teachers' knowledge on elementary geometry concepts

This text is based on a research, which is still in progress, whose main objective is to identify and understand what are the main difficulties of future mathematics teachers of basic education are, regarding their content knowledge in geometry in the context of the curricular unit of Geometry during their undergraduate degree. We chose a qualitative approach in the form of case study, in which data collection was done through observation, interviews, a diverse set of tasks, a diagnostic test and other documents. This paper focuses on the test given to prospective teachers at the beginning of the course. The preliminary analysis of the data points to a weak performance of preservice teachers in the test issues addressing elementary knowledge of Geometry.

A theoretical study on modelling the respiratory tract with ladder networks by means of intrinsic fractal geometry

Fractional order modeling of biological systems has received significant interest in the research community. Since the fractal geometry is characterized by a recurrent structure, the self-similar branching arrangement of the airways makes the respiratory system an ideal candidate for the application of fractional calculus theory. To demonstrate the link between the recurrence of the respiratory tree and the appearance of a fractional-order model, we develop an anatomically consistent representation of the respiratory system. This model is capable of simulating the mechanical properties of the lungs and we compare the model output with in vivo measurements of the respiratory input impedance collected in 20 healthy subjects. This paper provides further proof of the underlying fractal geometry of the human lungs, and the consequent appearance of constant-phase behavior in the total respiratory impedance.

Tool geometry evaluation for carbon reinforced composite laminates

The use of composite laminates in complex structures has increased significantly. However, there are still some issues when considering their use, mainly related with machining, leading to some difficulties and lack of acceptance. In this work, a methodology to evaluate drill geometry and feed rate based on thrust force and delamination extension is presented.

Full analysis of suspension geometry and chassis performance of Formula Student racing car

Formula Student events gather engineering students, who compete, designing, building and racing single-seater cars. The team of ISEP is working on its first car that soon will take part in this competition. This work aims to analyze the current design’s chassis, focusing on suspension geometry and frame’s performance. After analyzing results of the tests planned suggestions, that can be taken into consideration during design process of next cars will be presented. As the car has not been tested yet this work can also be helpful to explain its performance on the track later.

Geometry based visualization with OpenCL

Dissertação para obtenção do Grau de Mestre em Engenharia Informática

In situ measured cross section geometry of old timber structures and its influence on structural safety

Old timber structures may show significant variation in the cross section geometry along the same element, as a result of both construction methods and deterioration. As consequence, the definition of the geometric parameters in situ may be both time consuming and costly. This work presents the results of inspections carried out in different timber structures. Based on the obtained results, different simplified geometric models are proposed in order to efficiently model the geometry variations found. Probabilistic modelling techniques are also used to define safety parameters of existing timber structures, when subjected to dead and live loads, namely self-weight and wind actions. The parameters of the models have been defined as probabilistic variables, and safety of a selected case study was assessed using the Monte Carlo simulation technique. Assuming a target reliability index, a model was defined for both the residual cross section and the time dependent deterioration evolution. As a consequence, it was possible to compute probabilities of failure and reliability indices, as well as, time evolution deterioration curves for this structure. The results obtained provide a proposal for definition of the cross section geometric parameters of existing timber structures with different levels of decay, using a simplified probabilistic geometry model and considering a remaining capacity factor for the decayed areas. This model can be used for assessing the safety of the structure at present and for predicting future performance.

Mobile image processing to support educational geometry games

The mobile IT era is here, it is still growing and expanding at a steady rate and, most of all, it is entertaining. Mobile devices are used for entertainment, whether social through the so-called social networks, or private through web browsing, video watching or gaming. Youngsters make heavy use of these devices, and even small children show impressive adaptability and skill. However not much attention is directed towards education, especially in the case of young children. Too much time is usually spent in games which only purpose is to keep children entertained, time that could be put to better use such as developing elementary geometric notions. Taking advantage of this pocket computer scenario, it is proposed an application geared towards small children in the 6 – 9 age group that allows them to consolidate knowledge regarding geometric shapes, forming a stepping stone that leads to some fundamental mathematical knowledge to be exercised later on. To achieve this goal, the application will detect simple geometric shapes like squares, circles and triangles using the device’s camera. The novelty of this application will be a core real-time detection system designed and developed from the ground up for mobile devices, taking into account their characteristic limitations such as reduced processing power, memory and battery. User feedback was be gathered, aggregated and studied to assess the educational factor of the application.

Desenvolvimento e aplicação do algoritmo enxame de partículas na determinação da máxima injeção nodal em redes de energia elétrica

O objetivo desta dissertação é a determinação da máxima injeção nodal numa rede de energia elétrica, ou seja, qual o valor total máximo de potência ativa que é possível injetar e qual a sua distribuição pelos diversos nós da rede simultaneamente. Determinámos esta máxima injeção nodal em duas situações distintas: injeção não simultânea, injetando potência em um só nó de cada vez e injeção simultânea, injetando potência em todos os nós da rede simultaneamente. Sendo este um problema de natureza combinatória, utilizámos para esta determinação o algoritmo conhecido como nuvem ou enxame de partículas, adaptando-o ao nosso problema. Desenvolvemos o software na linguagem de programação Python utilizando o ambiente Eclipse. Para resolver o trânsito de energia utilizámos o programa PSSE University.Para os exemplos de aplicação utilizámos duas redes de energia elétrica, uma de 6 e outra de 14 barramentos. Estas redes foram baseadas nas redes IEEE 6 BUS e IEEE 14 BUS respetivamente. Concluímos que o algoritmo nuvem ou enxame de partículas cumpriu o objetivo traçado, obtendo as melhores soluções para cada um dos casos, máxima injeção nodal não simultânea e máxima injeção nodal simultânea. No contexto deste problema, o parâmetro chave do algoritmo, comprovado pelos ensaios feitos, é a velocidade máxima de deslocação das partículas, tomando valores típicos de 7 a 10 para a rede de 6 barramentos e de 20 a 25 para a de 14 barramentos.

A GIS extension model to calculate urban heat island intensity based on urban geometry

This paper presents a simulation model, which was incorporated into a Geographic Information System (GIS), in order to calculate the maximum intensity of urban heat islands based on urban geometry data. The method-ology of this study stands on a theoretical-numerical basis (Okeâ s model), followed by the study and selection of existing GIS tools, the design of the calculation model, the incorporation of the resulting algorithm into the GIS platform and the application of the tool, developed as exemplification. The developed tool will help researchers to simulate UHI in different urban scenarios.

Relação entre a persistência da condução pela via lenta nodal após ablação de taquicardia por reentrada nodal e a recorrência clínica

OBJETIVO: Verificar se a persistência de salto nodal relaciona-se à taxa de recorrência de taquicardia por reentrada nodal (TRN) após ablação com radiofreqüência (RF) da via lenta do nó atrioventricular. MÉTODOS: Num seguimento de 20±12 meses, foi analisada a recorrência de TRN em 126 pacientes consecutivos submetidos a ablação com RF da via lenta nodal. O critério de interrupção do procedimento foi a não reindução da TRN, após estimulação atrial programada, com e sem isoproterenol intravenoso. Ao final do procedimento, 98 pacientes não apresentavam salto nodal, e em 28 persistia o salto nodal e/ou o eco atrial. RESULTADOS: Houve recorrência clínica de TRN em 15 (11%) pacientes: 9 no grupo sem salto nodal e/ou eco atrial e em 6 do grupo que persistiu com salto e/ou eco atrial. A recorrência tendeu a ser maior no 2º grupo (9% vs 21%), mas não houve significância estatística entre os resultados (p=0,09). CONCLUSÃO: Desde que a TRN não possa ser induzida após a infusão de isoproterenol, a recorrência espontânea da arritmia após a ablação por RF da via lenta nodal não é diferente entre pacientes que persistem ou não com salto nodal e/ou eco atrial.