985 resultados para electronic stopping power
Resumo:
pp. 229-253
Resumo:
Power law (PL) distributions have been largely reported in the modeling of distinct real phenomena and have been associated with fractal structures and self-similar systems. In this paper, we analyze real data that follows a PL and a double PL behavior and verify the relation between the PL coefficient and the capacity dimension of known fractals. It is to be proved a method that translates PLs coefficients into capacity dimension of fractals of any real data.
Resumo:
Power laws, also known as Pareto-like laws or Zipf-like laws, are commonly used to explain a variety of real world distinct phenomena, often described merely by the produced signals. In this paper, we study twelve cases, namely worldwide technological accidents, the annual revenue of America׳s largest private companies, the number of inhabitants in America׳s largest cities, the magnitude of earthquakes with minimum moment magnitude equal to 4, the total burned area in forest fires occurred in Portugal, the net worth of the richer people in America, the frequency of occurrence of words in the novel Ulysses, by James Joyce, the total number of deaths in worldwide terrorist attacks, the number of linking root domains of the top internet domains, the number of linking root domains of the top internet pages, the total number of human victims of tornadoes occurred in the U.S., and the number of inhabitants in the 60 most populated countries. The results demonstrate the emergence of statistical characteristics, very close to a power law behavior. Furthermore, the parametric characterization reveals complex relationships present at higher level of description.
Resumo:
Advances in technology have produced more and more intricate industrial systems, such as nuclear power plants, chemical centers and petroleum platforms. Such complex plants exhibit multiple interactions among smaller units and human operators, rising potentially disastrous failure, which can propagate across subsystem boundaries. This paper analyzes industrial accident data-series in the perspective of statistical physics and dynamical systems. Global data is collected from the Emergency Events Database (EM-DAT) during the time period from year 1903 up to 2012. The statistical distributions of the number of fatalities caused by industrial accidents reveal Power Law (PL) behavior. We analyze the evolution of the PL parameters over time and observe a remarkable increment in the PL exponent during the last years. PL behavior allows prediction by extrapolation over a wide range of scales. In a complementary line of thought, we compare the data using appropriate indices and use different visualization techniques to correlate and to extract relationships among industrial accident events. This study contributes to better understand the complexity of modern industrial accidents and their ruling principles.
Resumo:
12th European Conference on Wireless Sensor Networks (EWSN 2015). 9 to 11, Feb, 2015. Porto, Portugal
Resumo:
Hindawi Publishing Corporation Bioinorganic Chemistry and Applications Volume 2010, Article ID 634597, 8 pages
Resumo:
First IFAC Workshop on Fractional Differentiation and Its Application - 19-21 July 2004, Enseirb, Bordeaux, France - FDA'04
Resumo:
This paper reports investigation on the estimation of the short circuit impedance of power transformers, using fractional order calculus to analytically study the influence of the diffusion phenomena in the windings. The aim is to better characterize the medium frequency range behavior of leakage inductances of power transformer models, which include terms to represent the magnetic field diffusion process in the windings. Comparisons between calculated and measured values are shown and discussed.
Resumo:
Dissertação para obtenção do Grau de Mestre em Energias Renováveis – Conversão Eléctrica e Utilização Sustentáveis
Resumo:
To improve surgical safety, and to reduce the mortality and surgical complications incidence, the World Health Organization (WHO) developed the Surgical Safety Checklist (SSC). The SSC is a support of information that aids health professionals to reduce the number of complications, induction of anaesthesia, period before skin incision and period before leaving the operating room (OR). The SSC was tested in several countries of the world and their results shown that after introduction of the SSC the incidence of patient complication lowered from 11.0% to 7.0% (P<0.001), the rate of death declined from 1.5% to 0.8% (P = 0.003) and the nurses recognized that patients identity was more often con rmed (81.6% to 94.2%, P<0.01) in many institutions. Recently the SSC was also implemented in Portuguese hospitals, which led us to its study in the real clinical environment. An observational study was performed: several health professionals were observed and interviewed, to understand the functioning of the SSC in an OR, during the clinical routine. The objective of this study was to understand the current use of the SSC, and how it may be improved in terms of usability, taking advantage of the technological advancements such as mobile applications. During two days were observed 14 surgeries, only 2 surgeries met the requirements for the three phases of the SSC, as de ned by the WHO. Of the remaining 12 observed surgeries, 9 surgeries completed the last phase at the correct time. It was also observed that only in 2 surgeries all the phases of the SSC were read aloud to the team and that, in 7 surgeries, several items were read aloud and answered but no one was checking the SSC, only after the end of the phase. The observational study results disclose that several health professionals do not meet with rules of the WHO manual. This study demonstrates that it is urgent to change the mindset of health professionals, and that di erent features in the SSC may be useful to make it more easy to use. With the results of the observational study, a SSC application proposal was developed with new functionalities to improve and aid the health professional in its use. In this application the user can chose between a SSC already created to a speci c surgery or to create a new SSC, adding and adapting some questions from the WHO standard. To create a new SSC, the application is connected to an online questionnaire builder (JotForm). The choice for this online questionnaire builder went through three essential characteristics: number of types of questions, mainly checkbox, radio button and text; the possibility of to create sections inside sections and the API. In addition, in this proposal the improvements are focused in forcing the user to focus in the work ow of the SSC and to save the input timestamps and any actions made by them. Therefore, the following features was implemented to achieve that goal: display one item of the SSC at a time; display the stage where the SSC is; do not allow going back to the previous step; do not allow going forward to the next item if the current is not lled; do not allow going forward to the next item if the time it took to ll the item was too short and log any action made by the user.
Resumo:
A very important part of the globally produced energy is consumed in buildings, being an important share frequently used in the HVAC systems. These ones are increasing both in performance and in complexity, taking advantage from the use of the recent advances in mechanical and power electronic devices, particularly in the speed variation field. However the improved efficiency only occurs while the HVAC unit is working in the conditions specified by the manufacturer, otherwise the energy consumption raises to values considerably higher than the nominal ones. The adequate maintenance enforces the system to run on its nominal performance and the contrary has undesirable impact both in the performance and in the system expected life time. Therefore, HVAC field maintenance assumes a very important role in the global building sustainability concept. This work presents some results of an incorrect use of HVAC and the associated electric energy overconsumption that can assume values 50% higher than those that occur when the installation is operated according to the adequate maintenance plan.
Resumo:
In this paper, we apply the following four power indices to the Portuguese Parliament: Shapley–Shubik index, Banzhaf index, Deegan–Packel index and Public Good Index. We also present the main notions related with simple games and discuss the features of each power index by means of their axiomatic characterizations.
Resumo:
Smart Grids (SGs) have emerged as the new paradigm for power system operation and management, being designed to include large amounts of distributed energy resources. This new paradigm requires new Energy Resource Management (ERM) methodologies considering different operation strategies and the existence of new management players such as several types of aggregators. This paper proposes a methodology to facilitate the coalition between distributed generation units originating Virtual Power Players (VPP) considering a game theory approach. The proposed approach consists in the analysis of the classifications that were attributed by each VPP to the distributed generation units, as well as in the analysis of the previous established contracts by each player. The proposed classification model is based in fourteen parameters including technical, economical and behavioural ones. Depending of the VPP strategies, size and goals, each parameter has different importance. VPP can also manage other type of energy resources, like storage units, electric vehicles, demand response programs or even parts of the MV and LV distribution network. A case study with twelve VPPs with different characteristics and one hundred and fifty real distributed generation units is included in the paper.
Multi-criteria optimisation approach to increase the delivered power in radial distribution networks
Resumo:
This study proposes a new methodology to increase the power delivered to any load point in a radial distribution network, through the identification of new investments in order to improve the repair time. This research work is innovative and consists in proposing a full optimisation model based on mixed-integer non-linear programming considering the Pareto front technique. The goal is to achieve a reduction in repair times of the distribution networks components, while minimising the costs of that reduction as well as non-supplied energy costs. The optimisation model considers the distribution network technical constraints, the substation transformer taps, and it is able to choose the capacitor banks size. A case study based on a 33-bus distribution network is presented in order to illustrate in detail the application of the proposed methodology.
Resumo:
Proceedings of the 13th International UFZ-Deltares Conference on Sustainable Use and Management of Soil, Sediment and Water Resources - 9–12 June 2015 • Copenhagen, Denmark