A New Heuristic Providing an Effective Initial Solution for a Simulated Annealing approach to Energy Resource Scheduling in Smart Grids

An intensive use of dispersed energy resources is expected for future power systems, including distributed generation, especially based on renewable sources, and electric vehicles. The system operation methods and tool must be adapted to the increased complexity, especially the optimal resource scheduling problem. Therefore, the use of metaheuristics is required to obtain good solutions in a reasonable amount of time. This paper proposes two new heuristics, called naive electric vehicles charge and discharge allocation and generation tournament based on cost, developed to obtain an initial solution to be used in the energy resource scheduling methodology based on simulated annealing previously developed by the authors. The case study considers two scenarios with 1000 and 2000 electric vehicles connected in a distribution network. The proposed heuristics are compared with a deterministic approach and presenting a very small error concerning the objective function with a low execution time for the scenario with 2000 vehicles.

Incapacidade auto-reportada e retorno à actividade profissional em utentes com dor crónica lombar

RESUMO: O absentismo à actividade profissional devido à condição de Dor Lombar apresenta-se como um problema de saúde pública com elevados custos económicos nas sociedades ocidentais. É estimado que cerca de 20% a 47% dos utentes com Dor Lombar não retornam à sua actividade profissional no período de 3 meses, sendo responsáveis por 75% a 90% de todos os custos e baixas médicas associadas à condição. Objectivo: O objectivo deste estudo foi analisar a capacidade de retorno à actividade profissional em utentes com Dor Crónica Lombar (DCL), que procuraram a Fisioterapia em situação de agudização dos seus sintomas, e averiguar a sua relação com os níveis de Incapacidade auto-reportados. Secundariamente pretendemos avaliar a influência das Crenças de medo-evitamento, nos níveis de Incapacidade auto-reportados. Metodologia: Foi efectuado um estudo correlacional prospectivo no qual se observou uma amostra de 56 utentes com DCL que tivessem apresentado novos episódios de agudização dos seus sintomas. Após 3 meses de follow-up (n=42) foi avaliado o “regresso ao trabalho em boas condições” e a sua relação com os níveis de Incapacidade iniciais, bem como o contributo das Crenças de medo-evitamento para essa Incapacidade funcional. Resultados: Foi verificada uma correlação negativa entre os níveis de Incapacidade funcional e o Sucesso no “regresso ao trabalho em boas condições” (ρ = -0.369; p =0.016), sendo que os scores mais elevados da Incapacidade correspondem à Falha nesse regresso. Verificámos também uma correlação positiva entre a existência das Crenças de medo-evitamento relativas ao Trabalho e a Incapacidade (r =0.511; p =0,001), apresentando estas Crenças um valor preditivo (β= 0.533; p =0.001) na Incapacidade auto-reportada. Conclusões: A capacidade de retorno à actividade profissional nos utentes com DCL, após um novo episódio de agudização dos seus sintomas, está relacionada com níveis de Incapacidade funcional. Os factores psicossociais, nomeadamente as Crenças de medo-evitamento relativas ao Trabalho apresentam um valor preditivo para essa Incapacidade auto-reportada.------------------------------ABSTRACT:Work-absenteeism due to the condition of Low Back Pain (LBP) presents itself as a public health problem with high economic costs in Western societies. It is estimated that 20% to 47% of patients with LBP not returned to their work-activity in period of 3 months, accounting for 75% to 90% of all medical costs and sickness compensation associated. Objective: The aim of the present study was to assess the ability to return to work on patients with chronic LBP, who searched for physical therapy in a situation of worsening of their symptoms, and examine their relationship with levels of self-reported disability. Secondly we intend to evaluate the influence of fear-avoidance beliefs to the levels of self-reported disability. Methods: We conducted a prospective cross-sectional study in which we observed 56 patients chronic LBP with new episodes of exacerbation of their symptoms. After a 3 months follow-up (n = 42) we evaluated the “return to work in good health” and its relationship with initial levels of disability and the contribution of fear-avoidance beliefs for that disability. Results: There was a negative correlation between levels of disability and “return to work in good health” success (ρ = -0.369, p = 0.016), with the highest scores correspond to the failure in the work-return. We also found a positive correlation between the existence of fear-avoidance beliefs for work and disability (r = 0.511; p = 0.001), with a predictive value of these fear-avoidance beliefs (β = 0.533; p = 0.001) in self-reported disability. Conclusions: The ability to return to work in chronic LBP patients, after a new episode of exacerbation of symptoms is related to the levels of functional disability. Psychosocial factors, including fear-avoidance beliefs for work showed a predictive value for the self-reported disability.

Numerical analysis of the initial conditions in fractional systems

Fractional dynamics is a growing topic in theoretical and experimental scientific research. A classical problem is the initialization required by fractional operators. While the problem is clear from the mathematical point of view, it constitutes a challenge in applied sciences. This paper addresses the problem of initialization and its effect upon dynamical system simulation when adopting numerical approximations. The results are compatible with system dynamics and clarify the formulation of adequate values for the initial conditions in numerical simulations.

Produção de Biodiesel em reator de ultrassons

A contínua subida dos preços dos combustíveis fósseis tradicionais aliada à crescente pressão por parte de várias instituições mundiais para uma política “verde” no que diz respeito aos combustíveis, levam a um aumento da procura dos biocombustíveis e é neste contexto que surge o biodiesel como um dos principais intervenientes. O biodiesel pode ser definido como um derivado éster monoalquílico de ácidos gordos de cadeia longa proveniente de fontes renováveis como óleos vegetais ou gorduras animais e que apresenta características semelhantes ao diesel de petróleo, podendo ser utilizado sem qualquer problema em motores de ignição por compressão. Este trabalho apresenta como principal objetivo o estudo da aplicação da tecnologia de ultrassons na produção de biodiesel. Foi utilizado neste trabalho como matéria-prima um óleo doméstico usado. Este óleo foi previamente filtrado sendo depois analisado o seu índice de acidez para avaliar o seu teor em ácidos gordos livres. O valor obtido para o índice de acidez do óleo foi de 1,91 mg KOH/g, um valor relativamente baixo permitindo a sua utilização sem ser necessário um tratamento inicial via esterificação para diminuir a acidez do mesmo. Foram realizados três ensaios de reação independentes, o primeiro recorrendo ao método tradicional de produção de biodiesel através de transesterificação e recorrendo a agitação mecânica e aquecimento, o segundo utilizando uma sonda de ultrassons com a potência de 500 W e um terceiro ensaio de reação utilizando uma sonda de ultrassons de 2000 W. Em todas as reações foi utilizada uma proporção de 1:5 de óleo usado e metanol e 0,5 % (em relação á massa de óleo utilizada) de catalisador metilato de sódio. Todas as alíquotas recolhidas durante os ensaios foram analisadas através de cromatografia gasosa de modo a determinar o conteúdo em ésteres presente em cada uma delas. A reação convencional teve uma duração total de 150 minutos e decorreu a uma temperatura de 65ºC e a agitação constante de 500 rpm. Ao longo da reação foram retiradas alíquotas de cerca de 25 ml, que foram tratadas de imediato e posteriormente analisadas de modo a estudar-se o comportamento da reação ao longo do tempo. A percentagem de ésteres metílicos no biodiesel obtida ao fim de 90 minutos foi de 81,3%. Em seguida realizou-se uma reação utilizando uma sonda de ultrassons de 500 W de potência mergulhada num recipiente reacional devidamente isolado com uma rolha de cortiça de modo a minimizar as perdas de metanol por evaporação. O tempo total de reação foi de 90 minutos e foram-se retirando alíquotas de cerca de 25 ml para acompanhar o desenrolar da reação, tendo-se obtido uma percentagem de ésteres metílicos de 85,9% ao fim dos 90 minutos. Foi realizada por fim um terceiro ensaio de reação utilizando uma sonda de 2000 W com uma duração total de 90 minutos, tendo-se obtido resultados pouco satisfatórios (77,7%), provavelmente devido a algum problema operacional relacionado com a sonda de ultrassons utilizada ou devido a uma geometria do reator pouco eficiente. Os produtos resultantes da reação convencional e da reação utilizando a sonda de ultrassons de 500 W, assim como o óleo utilizado como matéria-prima foram caracterizados em termos de índice de acidez, densidade a 15ºC e viscosidade a 40ºC.

A Prospective Assessment of Renal Transplantation Versus Haemodialysis: Which Therapeutic Modality Is Good Value for Society?

Background: Economic evaluations help health authorities facing budget constraints. This study compares the health-related quality of life (HRQOL) and costs in patient subgroups on haemodialysis (HD) and renal transplantation (KT). Methods: In a prospective study with follow-up of 1-3 years, we performed a costutility analysis of KT vs. HD, adopting a lifetime horizon. A societal perspective was taken. Costs for organ procurement, KT eligibility, transplant surgery and follow-up of living donors were included. Key clinical events were recorded. HRQOL was assessed using the EuroQol instrument. Results: The HRQOL remained stable on HD patients. After KT, mean utility score improved at 3 months while mean EQ-VAS scores showed a sustained improvement. Mean annual cost for HD was 32,567.57€. Mean annual costs for KT in the year-1 and in subsequent years were, 60,210.09€ and 12,956.77€ respectively. Cost for initial hospitalization averaged 18,740.74€. HLA-mismatches increased costs by 75% for initial hospitalization (p < 0.001) and 41% in the year-1 (p < 0.05), and duplicate the risk of readmission in the year-1 (p < 0.05). The incremental costutility ratio was 5,534.46€/QALY, increasing 35% when costs for organ procurement were added. KT costs were 41,541.63€ more but provided additional 7.51 QALY. Conclusions: The KT is cost-effective compared with HD. Public funding should reflect the value created by the intervention and adapt to the organ demand.

What is the value of value-at-risk after all?: A conditional approach using quantile regressions

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Finance from the NOVA – School of Business and Economics

Continente Choose&Drive

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics

Business model analysis of Mobitto: How to solve the chicken and egg problem of a multi-sided platform?

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics

Constraint reasoning with local search for continuous optimization

Optimization is a very important field for getting the best possible value for the optimization function. Continuous optimization is optimization over real intervals. There are many global and local search techniques. Global search techniques try to get the global optima of the optimization problem. However, local search techniques are used more since they try to find a local minimal solution within an area of the search space. In Continuous Constraint Satisfaction Problems (CCSP)s, constraints are viewed as relations between variables, and the computations are supported by interval analysis. The continuous constraint programming framework provides branch-and-prune algorithms for covering sets of solutions for the constraints with sets of interval boxes which are the Cartesian product of intervals. These algorithms begin with an initial crude cover of the feasible space (the Cartesian product of the initial variable domains) which is recursively refined by interleaving pruning and branching steps until a stopping criterion is satisfied. In this work, we try to find a convenient way to use the advantages in CCSP branchand- prune with local search of global optimization applied locally over each pruned branch of the CCSP. We apply local search techniques of continuous optimization over the pruned boxes outputted by the CCSP techniques. We mainly use steepest descent technique with different characteristics such as penalty calculation and step length. We implement two main different local search algorithms. We use “Procure”, which is a constraint reasoning and global optimization framework, to implement our techniques, then we produce and introduce our results over a set of benchmarks.

A type system for value-dependent information flow analysis

Information systems are widespread and used by anyone with computing devices as well as corporations and governments. It is often the case that security leaks are introduced during the development of an application. Reasons for these security bugs are multiple but among them one can easily identify that it is very hard to define and enforce relevant security policies in modern software. This is because modern applications often rely on container sharing and multi-tenancy where, for instance, data can be stored in the same physical space but is logically mapped into different security compartments or data structures. In turn, these security compartments, to which data is classified into in security policies, can also be dynamic and depend on runtime data. In this thesis we introduce and develop the novel notion of dependent information flow types, and focus on the problem of ensuring data confidentiality in data-centric software. Dependent information flow types fit within the standard framework of dependent type theory, but, unlike usual dependent types, crucially allow the security level of a type, rather than just the structural data type itself, to depend on runtime values. Our dependent function and dependent sum information flow types provide a direct, natural and elegant way to express and enforce fine grained security policies on programs. Namely programs that manipulate structured data types in which the security level of a structure field may depend on values dynamically stored in other fields The main contribution of this work is an efficient analysis that allows programmers to verify, during the development phase, whether programs have information leaks, that is, it verifies whether programs protect the confidentiality of the information they manipulate. As such, we also implemented a prototype typechecker that can be found at http://ctp.di.fct.unl.pt/DIFTprototype/.

O ensino da flauta de bisel em grupo como inovação pedagógica: Uma investigação-ação no 2.º Ciclo do Ensino Básico

Tese de Doutoramento em Estudos da Criança (Especialidade em Educação Musical)

Percutaneous mechanical mitral commissurotomy performed with a Cribier's metallic valvulotome. Initial results

OBJECTIVE: To evaluate the immediate results of percutaneous mechanical mitral commissurotomy. METHODS: Thirty patients underwent percutaneous mechanical mitral commissurotomy performed with a Cribier's metallic valvulotome from 8/11/99 to 2/4/00. Mean age was 30.7 years, and 73.3% were women. With regards to functional class, 63.3% were class III, and 36.7% were class IV. The echocardiographic score had a mean value of 7.5± 1.8. RESULTS: The mitral valve area increased from 0.97±0.15cm² to 2.16±0.50cm² (p>0.0001). The mean diastolic gradient decreased from 17.9±5.0mmHg to 3.2±1.4mmHg. The mean left atrial pressure decreased from 23.6±5.4mmHg to 8.6±3.1mmHg, (p>0.0001). Systolic pressure in the pulmonary artery decreased from 52.7±18.3mmHg to 32.2±7.4mmHg. Twenty-nine cases were successful. One patient developed severe mitral regurgitation. Interatrial septal defect was observed and one patient. One patient had cardiac tamponade due to left ventricular perforation. No deaths occurred. CONCLUSION: This method has proven to be safe and efficient in the treatment of rheumatic mitral stenosis. The potential advantage is that it can be used multiple times after sterilization, which decreases procedural costs significantly.

Malolactic fermentation in winemaking: evaluation of operational parameters

Dissertação de mestrado em Bioengenharia

Population dynamics of 0-group flounder (Platichthys flesus L.) in Galway Bay, West of Ireland and the value of flounder from shore angling tourism in Ireland

The economic value of flounder from shore angling around Ireland was assessed. Flounder catches from shore angling tournaments around Ireland were related to domestic and overseas shore angling expenditure in order to determine an economic value for the species. Temporal trends in flounder angling catches, and specimen (trophy) flounder reports were also investigated. Flounder was found to be the most caught shore angling species in competitions around Ireland constituting roughly one third of the shore angling competition catch although this did vary by area. The total value of flounder from shore angling tourism was estimated to be of the order of €8.4 million. No significant temporal trends in flounder angling catches and specimen reports were found. Thus there is no evidence from the current study for any decline in flounder stocks. The population dynamics of 0-group flounder during the early benthic stage was investigated at estuarine sites in Galway Bay, west of Ireland. Information was analysed from the March to June sampling period over five years (2002 to 2006). Spatial and temporal variations in settlement and population length structure were analysed between beach and river habitats and sites. Settlement of flounder began from late March to early May of each year, most commonly in April. Peak settlement was usually in April or early May. Settlement was recorded earlier than elsewhere, although most commonly was similar to the southern part of the UK and northern France. Settlement was generally later in tidal rivers than on sandy beaches. Abundance of 0-group flounder in Galway Bay did not exhibit significant inter -annual variability. 0-group flounder were observed in dense aggregations of up to 105 m'2, which were patchy in distribution. Highest densities of 0-group flounder were recorded in limnetic and oligohaline areas as compared with the lower densities in polyhaline and to a lesser extent mesohaline areas. Measurements to of salinity allowed the classification of beaches, and tidal river sections near the mouth, into a salinity based scheme for length comparisons. Beaches were classified as polyhaline,the lower section of rivers as mesohaline, and the middle and upper sections as oligohaline. Over the March to June sampling period 0-group flounder utilised different sections at different length ranges and were significantly larger in more upstream sections. During initial settlement in April, 0-group flounder of 8-10 mm (standard length, SL) were present in abundance on polyhaline sandy beaches. By about 10mm (SL), flounder were present in all polyhaline, mesohaline and (oligohaline) sections. 0-group flounder became absent or in insignificant numbers in polyhaline and mesohaline sections in a matter of weeks after first appearance. From April to June, 0-group flounder of 12-30mm (SL) were found in more upstream locations in the oligohaline sections. About one month (May or June) after initial settlement, 0-group flounder became absent from the oligohaline sections. Concurrently, flounder start to reappear in mesohaline and polyhaline areas at approximately 30mm (SL) in June. The results indicate 0-group flounder in the early benthic stage are associated with low salinity areas, but as they grow, this association diminishes. Results strongly suggest that migration of 0-group flounder between habitats takes place during the early benthic phase.

The production of vermicompost from dairy sludge and its value as a plant growth medium

Dairy sludge generated at Glanbia Ingredients Ltd., Kilkenny has up until now been landspread. This study investigated the feasibility of using earthworms to vermicompost the sludge as an alternative method of treatment. It was found that high levels of ammonia in the sludge led to earthworm fatality but that by manually aerating the sludge the ammonia could be volatilised or by adding zeolite the ammonia could be absorbed, thus solving the problem. In a medium scale trial, the earthworm species Dendrobaena veneta and Eisenia fetida dominated the polyculture. Earthworms grew and generated cocoons during vermicomposting. During vermicomposting no leachate was generated. Nutrient changes took place during vermicomposting. There were high levels of nitrate, increased calcium and sulphate in the vermicomposted dairy sludge. The amount of magnesium, potassium and chloride did not change, while phosphate was undetectable after vermicomposting. The levels of nitrate and phosphate were good indicators of the extent of vermicomposting. The vermicomposted dairy sludge provided improved growth and yields of radishes and barley compared to the dairy sludge and control. Compared to the vermicompost, the dairy sludge provided heavier ryegrass yields and more marigolds with larger flower diameters. Generally, it is the amount of phosphate in dairy sludge that dictates how much can be applied as a fertiliser on land. Vermicomposting reduced the amount of phosphate to an undetectable level but on the other hand created a problem of high nitrate levels. In a pot trial with grass grown in vermicompost the nitrate leached from the vermicompost. In field conditions the leaching of nitrate might occur and could cause an increased risk of contamination of groundwater and watercourses.