Distributed Model Predictive Control for Housing with Hourly Auction of Available Energy

This paper presents a distributed model predictive control (DMPC) for indoor thermal comfort that simultaneously optimizes the consumption of a limited shared energy resource. The control objective of each subsystem is to minimize the heating/cooling energy cost while maintaining the indoor temperature and used power inside bounds. In a distributed coordinated environment, the control uses multiple dynamically decoupled agents (one for each subsystem/house) aiming to achieve satisfaction of coupling constraints. According to the hourly power demand profile, each house assigns a priority level that indicates how much is willing to bid in auction for consume the limited clean resource. This procedure allows the bidding value vary hourly and consequently, the agents order to access to the clean energy also varies. Despite of power constraints, all houses have also thermal comfort constraints that must be fulfilled. The system is simulated with several houses in a distributed environment.

A Voltage Limiter Circuit for Indoor Light Energy Harvesting Applications

A voltage limiter circuit for indoor light energy harvesting applications is presented. This circuit is a part of a bigger system, whose function is to harvest indoor light energy, process it and store it, so that it can be used at a later time. This processing consists on maximum power point tracking (MPPT) and stepping-up, of the voltage from the photovoltaic (PV) harvester cell. The circuit here described, ensures that even under strong illumination, the generated voltage will not exceed the limit allowed by the technology, avoiding the degradation, or destruction, of the integrated die. A prototype of the limiter circuit was designed in a 130 nm CMOS technology. The layout of the circuit has a total area of 23414 mu m(2). Simulation results, using Spectre, are presented.

Start-up circuit for low-power indoor light energy harvesting applications

A start-up circuit, used in a micro-power indoor light energy harvesting system, is described. This start-up circuit achieves two goals: first, to produce a reset signal, power-on-reset (POR), for the energy harvesting system, and secondly, to temporarily shunt the output of the photovoltaic (PV) cells, to the output node of the system, which is connected to a capacitor. This capacitor is charged to a suitable value, so that a voltage step-up converter starts operating, thus increasing the output voltage to a larger value than the one provided by the PV cells. A prototype of the circuit was manufactured in a 130 nm CMOS technology, occupying an area of only 0.019 mm(2). Experimental results demonstrate the correct operation of the circuit, being able to correctly start-up the system, even when having an input as low as 390 mV using, in this case, an estimated energy of only 5.3 pJ to produce the start-up.

GenERATIONS of Azoreans and Renewable Energy: a comparative study

Avan��a dados das perspetivas de diferentes gera����es sobre quest��es ambientais e consumo energ��tico.

Avalia����o energ��tica de uma escola

Mestrado em Engenharia Qu��mica

Dosimetric effect by shallow air cavities in high energy electron beams

This study evaluates the dosimetric impact caused by an air cavity located at 2 mm depth from the top surface in a PMMA phantom irradiated by electron beams produced by a Siemens Primus linear accelerator. A systematic evaluation of the effect related to the cavity area and thickness as well as to the electron beam energy was performed by using Monte Carlo simulations (EGSnrc code), Pencil Beam algorithm and Gafchromic EBT2 films. A home-PMMA phantom with the same geometry as the simulated one was specifically constructed for the measurements. Our results indicate that the presence of the cavity causes an increase (up to 70%) of the dose maximum value as well as a shift forward of the position of the depthedose curve, compared to the homogeneous one. Pronounced dose discontinuities in the regions close to the lateral cavity edges are observed. The shape and magnitude of these discontinuities change with the dimension of the cavity. It is also found that the cavity effect is more pronounced (6%) for the 12 MeV electron beam and the presence of cavities with large thickness and small area introduces more significant variations (up to 70%) on the depthedose curves. Overall, the Gafchromic EBT2 film measurements were found in agreement within 3% with Monte Carlo calculations and predict well the fine details of the dosimetric change near the cavity interface. The Pencil Beam calculations underestimate the dose up to 40% compared to Monte Carlo simulations; in particular for the largest cavity thickness (2.8 cm).

Cyclotech - contribution to solve the Technetium shortage by using low energy medical cyclotrons

This paper presents work in progress, to develop an efficient and economic way to directly produce Technetium 99metastable (99mTc) using low-energy cyclotrons. Its importance is well established and relates with the increased global trouble in delivering 99mTc to Nuclear Medicine Departments relying on this radioisotope. Since the present delivery strategy has clearly demonstrated its intrinsic limits, our group decided to follow a distinct approach that uses the broad distribution of the low energy cyclotrons and the accessibility of Molybdenum 100 (100Mo) as the Target material. This is indeed an important issue to consider, since the system here presented, named CYCLOTECH, it is not based on the use of Highly Enriched (or even Low Enriched) Uranium 235 (235U), so entirely complying with the actual international trends and directives concerning the use of this potential highly critical material. The production technique is based on the nuclear reaction 100Mo (p,2n) 99mTc whose production yields have already been documented. Until this moment two Patent requests have already been submitted (the first at the INPI, in Portugal, and the second at the USPTO, in the USA); others are being prepared for submission on a near future. The object of the CYCLOTECH system is to present 99mTc to Nuclear Medicine radiopharmacists in a routine, reliable and efficient manner that, remaining always flexible, entirely blends with established protocols. To facilitate workflow and Radiation Protection measures, it has been developed a Target Station that can be installed on most of the existing PET cyclotrons and that will tolerate up to 400 ��A of beam by allowing the beam to strike the Target material at an adequately oblique angle. The Target Station permits the remote and automatic loading and discharge of the Targets from a carriage of 10 Target bodies. On other hand, several methods of Target material deposition and Target substrates are presented. The object was to create a cost effective means of depositing and intermediate the target material thickness (25 - 100��m) with a minimum of loss on a substrate that is able to easily transport the heat associated with high beam currents. Finally, the separation techniques presented are a combination of both physical and column chemistry. The object was to extract and deliver 99mTc in the identical form now in use in radiopharmacies worldwide. In addition, the Target material is recovered and can be recycled.

The adjusted effect of maternal body mass index, energy and macronutrient intakes during pregnancy, and gestational weight gain on body composition of full-term neonates

Objective - To evaluate the effect of prepregnancy body mass index (BMI), energy and macronutrient intakes during pregnancy, and gestational weight gain (GWG) on the body composition of full-term appropriate-for-gestational age neonates. Study Design - This is a cross-sectional study of a systematically recruited convenience sample of mother-infant pairs. Food intake during pregnancy was assessed by food frequency questionnaire and its nutritional value by the Food Processor Plus (ESHA Research Inc, Salem, OR). Neonatal body composition was assessed both by anthropometry and air displacement plethysmography. Explanatory models for neonatal body composition were tested by multiple linear regression analysis. Results -���A total of 100 mother-infant pairs were included. Prepregnancy overweight was positively associated with offspring weight, weight/length, BMI, and fat-free mass in the whole sample; in males, it was also positively associated with midarm circumference, ponderal index, and fat mass. Higher energy intake from carbohydrate was positively associated with midarm circumference and weight/length in the whole sample. Higher GWG was positively associated with weight, length, and midarm circumference in females. Conclusion���- Positive adjusted associations were found between both prepregnancy BMI and energy intake from carbohydrate and offspring body size in the whole sample. Positive adjusted associations were also found between prepregnancy overweight and adiposity in males, and between GWG and body size in females.

Materiais de mudan��a de fase em revestimentos

Disserta����o para obten����o do grau de Mestre em Engenharia Civil na ��rea de especializa����o em Edifica����es

Reabilita����o de edif��cios: enquadramento e estudo da reabilita����o num grupo empresarial

Disserta����o para obten����o do grau de Mestre em Engenharia Civil na ��rea de Especializa����o em Edifica����es

Mapping stability : real rational maps of degree zero

In memory of our beloved Professor Jos�� Rodrigues Santos de Sousa Ramos (1948-2007), who Jo��o Cabral, one of the authors of this paper, had the honor of being his student between 2000 and 2006, we wrote this paper following the research by experimentation, using the new technologies to capture a new insight about a problem, as him so much love to do it. His passion was to create new relations between different fields of mathematics. He was a builder of bridges of knowledge, encouraging the birth of new ways to understand this science. One of the areas that Sousa Ramos researched was the iteration of maps and the description of its behavior, using the symbolic dynamics. So, in this issue of this journal, honoring his memory, we use experimental results to find some stable regions of a specific family of real rational maps, the ones that he worked with Jo��o Cabral. In this paper we describe a parameter space (a,b) to the real rational maps fa,b(x) = (x2 ���a)/(x2 ���b), using some tools of dynamical systems, as the study of the critical point orbit and Lyapunov exponents. We give some results regarding the stability of these family of maps when we iterate it, specially the ones connected to the order 3 of iteration. We hope that our results would help to understand better the behavior of these maps, preparing the ground to a more efficient use of the Kneading Theory on these family of maps, using symbolic dynamics.

Avalia����o energ��tica do Complexo Municipal de Piscinas de Folgosa

O presente trabalho insere-se no ��mbito do Mestrado de Engenharia Qu��mica, ramo Optimiza����o Energ��tica na Ind��stria Qu��mica e pretende-se efectuar a avalia����o energ��tica do Complexo Municipal de Piscinas de Folgosa, localizado no Concelho da Maia, tendo como principais bases os Decretos-Lei 78, 79 e 80 de 04 de Abril 2006. Uma vez que a ��rea ��til de pavimento do presente edif��cio �� superior a 1000 m2, encontra-se englobado no conceito de Grande Edif��cio de Servi��os (GES). A escolha do Complexo Municipal de Piscinas de Folgosa para a realiza����o do presente estudo prendeu-se com o facto de ser um objectivo da C��mara Municipal, mais concretamente do Departamento de Conserva����o e Manuten����o de Estruturas Municipais, dar inicio aos procedimentos necess��rios para a certifica����o energ��tica dos diversos edif��cios Municipais, aliado ao facto das piscinas serem um tipo de edif��cio desportivo de elevada complexidade em termos de gest��o, um grande consumidor de energia e possuidor de uma elevada diversidade de equipamentos. O objectivo principal ser�� o de caracterizar energeticamente o edif��cio e optimizar os consumos do mesmo, de forma a reduzir, n��o s�� os consumos energ��ticos e respectiva factura, mas tamb��m nas emiss��es dos gases de efeito de estufa (CO2), pelo que a ordem de trabalhos inclui a realiza����o de: - Avalia����o Energ��tica de acordo com o n.��1 do artigo 2�� e artigo 34�� do D. L. 79/2006; - Verifica����o dos Requisitos de Condu����o e manuten����o das instala����es de Aquecimento, Ventila����o e Ar Condicionado (AVAC); - Caracteriza����o Energ��tica do Edif��cio ��� ��ndice de Efici��ncia Energ��tica. A metodologia seguida baseou-se na utilizada para a realiza����o de uma auditoria energ��tica, sendo que foram contempladas as seguintes etapas: estudo pormenorizado da legisla����o referente �� certifica����o de edif��cios; realiza����o de um levantamento de consumos energ��ticos reais da instala����o (com base nas facturas energ��ticas); das suas caracter��sticas funcionais e levantamento dos v��rios equipamentos consumidores de energia. O Complexo Municipal de Piscinas de Folgosa �� uma instala����o cuja m��dia de consumo de energia el��ctrica nos ��ltimos tr��s anos foi de 445969 kWh/ano e de 87300 m3 de g��s natural, representando um consumo global de energia prim��ria de 174,85 tep/ano. De acordo com o Sistema de Certifica����o Energ��tica o ��ndice de Efici��ncia Energ��tica determinado �� de 54,50 kgep/m2 .ano. Uma vez que o IEE determinado �� superior ao valor de IEERefer��ncia existentes, o edif��cio estar�� obrigado ao cumprimento de um Plano de Racionaliza����o Energ��tica (PRE). �� apresentado um conjunto de medidas que visam uma redu����o do consumo de energia do edif��cio e consequentemente uma melhoria no ��ndice de Efici��ncia Energ��tica.

Reabilita����o sustent��vel de edif��cio de habita����o, em constru����o tradicional, no Baixo Alentejo

Disserta����o de Final de Mestrado para obten����o do grau de Mestre em Engenharia Civil Especializa����o em Edifica����es

Curiosidades num��ricas : O nascimento do zero

Neste artigo, vamos viajar no tempo e assistir ao nascimento do zero. (...) As origens da Matem��tica remontam a alguns milhares de anos antes das primeiras civiliza����es e derivaram da necessidade de contar objetos. Em primeiro lugar, foi necess��rio distinguir um objeto de muitos objetos (ca��ar um p��ssaro ou muitos p��ssaros). Com o passar do tempo, a linguagem desenvolveu-se para distinguir entre um, dois e muitos. Em seguida, um, dois, tr��s e muitos. (...) O passo seguinte consistiu em agrupar objetos de forma a facilitar a contagem. (...) A verdade �� que os antigos gostavam de contar com as partes do seu corpo. Os favoritos eram o 5 (uma m��o), o 10 (as duas m��os) e o 20 (ambas as m��os e os p��s). O sistema num��rico de base 10 acabou por vingar em muitas culturas e isso refletiu-se no vocabul��rio que ainda hoje utilizamos. Em portugu��s, as palavras ���onze���, ���doze��� e ���treze��� derivam do latim (undecim, duodecim e tredecim), significando ���dez e um���, ���dez e dois��� e ���dez e tr��s���. (...) Os sistemas antigos de numera����o n��o contemplaram o zero. A verdade �� que ningu��m precisava de registar ���zero ovelhas��� nem contar ���zero aves���. Em vez de dizer ���tenho zero lan��as���, bastava afirmar ���n��o tenho lan��as���. Como n��o era preciso um n��mero para expressar a falta de alguma coisa, n��o ocorreu a necessidade de atribuir um s��mbolo �� aus��ncia de objetos. (...) O sistema de numera����o grego, tal como o eg��pcio, ignorou por completo o zero. O zero nasceu noutra zona do globo: no Oriente, concretamente, no Crescente F��rtil do atual Iraque. O sistema de numera����o babil��nico era, de certa forma, invulgar. Os babil��nios tinham um sistema sexagesimal, de base 60, e usavam apenas duas marcas para representar os seus n��meros: uma cunha simples para representar o 1 e uma cunha dupla para representar o 10. (...) os babil��nios tiveram uma excelente ideia: inventaram um sistema de numera����o posicional, em que os n��meros s��o representados por sequ��ncias de s��mbolos, sendo que o valor de cada s��mbolo depende da posi����o que ocupa nessa sequ��ncia. (...) Para os babil��nios, o zero era um simples marca-lugar; um s��mbolo para uma casa em branco no ��baco. O zero n��o ocupava um lugar na hierarquia dos n��meros; n��o tinha ainda assumido a sua posi����o estrat��gica na reta num��rica como o n��mero que separa os n��meros positivos dos negativos. (...)

Curiosidades num��ricas : Das origens do zero aos desafios do novo mil��nio

(...) Tal como os babil��nios, os maias do M��xico e da Am��rica Central criaram um sistema de numera����o posicional. A diferen��a �� que o sistema era vigesimal, de base 20. Os maias tamb��m recorriam ao zero para a escrita dos n��meros e utilizavam dois tipos de d��gitos (...) O sistema de numera����o indiano acabou por evoluir de um sistema do tipo grego para um sistema do tipo babil��nico (...) Os indianos encararam com naturalidade a exist��ncia de n��meros negativos, bem como da reta num��rica em que o zero assumia finalmente o estatuto de n��mero com a posi����o estrat��gica de separar os n��meros positivos dos negativos. (...) A pr��pria palavra ���zero��� tem ra��zes hindu-��rabes. O nome indiano para zero era sunya, que significava ���vazio���. Os ��rabes transformaram-no em sifr. Por sua vez, os ocidentais adotaram uma designa����o que soasse a latim ��� zephirus, que �� a raiz da nossa palavra ���zero���. (...) No Ocidente, o medo do infinito e o horror ao vazio perpetuaram-se durante s��culos. Partindo do universo pitag��rico, Arist��teles e Ptolemeu defendiam um cosmos finito em extens��o, mas cheio de mat��ria. O universo estava contido numa ���casca de noz��� revestida pela esfera das estrelas fixas. (...) A falta do zero n��o s�� impediu o desenvolvimento da Matem��tica no Ocidente como, indiretamente, introduziu alguma confus��o no nosso calend��rio. Todos nos lembramos das d��vidas que surgiram com a viragem recente de s��culo e mil��nio: dever��amos festejar a mudan��a de s��culo e mil��nio na passagem de ano de 1999 para 2000 ou de 2000 para 2001? A resposta correta �� a segunda op����o e a justifica����o �� simples: o nosso calend��rio n��o contempla o zero. (...) Com o Renascimento, o universo de casca de noz partiu-se, o vazio e o infinito ultrapassaram por completo os preconceitos da funda����o aristot��lica da Igreja e abriram caminho para um desenvolvimento not��vel da ci��ncia e, em particular, da Matem��tica. O zero assumiu um papel chave no desenvolvimento de v��rias ��reas da Matem��tica, entre elas destaca-se o c��lculo diferencial e integral. O edif��cio matem��tico, que outrora tinha sido alicer��ado partindo da necessidade de contar ovelhas e demarcar propriedades, erguia-se agora bem alto: as regras da Natureza podiam ser descritas por equa����es e a Matem��tica era a chave para desvendar os segredos do Universo. (...) O zero n��o pode ser ignorado. De facto, o zero est�� na base de muitos dos segredos do Universo, a desvendar neste novo mil��nio.