Estudi i guia docent per a modelatge i simulació de sistemes mitjançant l'entron ARENA

Aquest projecte es basa en el modelatge i simulació de sistemes utilitzant un simulador digital, i pretén ser una guia docent com a eina d’ajuda per a una assignatura que, a priori, s’impartirà a la Universitat de Vic. La simulació és una tècnica que permet representar el comportament de processos (físics, productius, de serveis, etc.) sense necessitat d’accedir al sistema real. Per analitzar, estudiar i millorar el comportament d’un sistema mitjançant la tècnica de la simulació digital és necessari primer desenvolupar un model conceptual que descrigui les variables d’interès, i després implementar-lo en un simulador per poder analitzar els resultats. ARENA és el software de simulació que s’estudia en aquest projecte i es presenta com una eina que permet la descripció complerta de l’experiència que una entitat desenvolupa a l’interior del sistema mentre flueix a través d’aquest. En concret s’utilitza la versió ARENA 10.0. Pel que fa a l’estructura del projecte, primerament s’introdueixen conceptes teòrics referents a la simulació, així com avantatges i inconvenients i els camps d’aplicació de la simulació. Seguidament i ja centrats en l’Arena, s’analitza un exemple senzill per començar-ne a veure el funcionament. Posteriorment, es van estudiant varis exemples amb complexitat progressiva. Aquests exemples es desenvolupen pas a pas de manera que es puguin anar provant amb el simulador. En el transcurs del projecte es van estudiant les eines de l’Arena i les seves possibilitats, així com els resultats obtinguts i les interpretacions d’aquests. Aquest projecte pretén, doncs, donar conceptes introductoris en el camp de la simulació en general, i, en particular, descriure eines bàsiques sobre el funcionament de l’Arena.

Sistemes encastats en temps real

Resum En l’actualitat, els sistemes electrònics de processament de dades són cada cop més significatius dins del sector industrial. Són moltes les necessitats que sorgeixen en el món dels sistemes d’autentificació, de l’electrònica aeronàutica, d’equips d’emmagatzemament de dades, de telecomunicacions, etc. Aquestes necessitats tecnològiques exigeixen ser controlades per un sistema fiable, robust, totalment dependent amb els esdeveniments externs i que compleixi correctament les restriccions temporals imposades per tal de que realitzi el seu propòsit d’una manera eficient. Aquí és on entren en joc els sistemes encastats en temps real, els quals ofereixen una gran fiabilitat, disponibilitat, una ràpida resposta als esdeveniments externs del sistema, una alta garantia de funcionament i una àmplia possibilitat d’aplicacions. Aquest projecte està pensat per a fer una introducció al món dels sistemes encastats, com també explicar el funcionament del sistema operatiu en temps real FreeRTOS; el qual utilitza com a mètode de programació l’ús de tasques independents entre elles. Donarem una visió de les seves característiques de funcionament, com organitza tasques mitjançant un scheduler i uns exemples per a poder dissenyar-hi aplicacions.

Virtualització de servidors. Avantatges. Implantació en una PIME real

 En la societat d’avui dia, les empreses depenen en gran part dels seus recursos informàtics. La seva capacitat de supervivència i innovació en el mercat actual, on la competitivitat és cada dia més forta, passa per una infraestructura informàtica que els permeti, no només desplegar i implantar ordinadors i servidors de manera ràpida i eficient sinó que també les protegeixi contra parades del sistema informàtic, problemes amb servidors, caigudes o desastres físics de hardware.Per evitar aquests problemes informàtics susceptibles de poder parar el funcionament d’una empresa es va començar a treballar en el camp de la virtualització informàtica amb l’objectiu de poder trobar solucions a aquests problemes a la vegada que s’aprofitaven els recursos de hardware existents d’una manera més òptim a i eficient, reduint així també el cost de la infraestructura informàtica.L’objectiu principal d’aquest treball és veure en primer pla la conversió d’una empresa real amb una infraestructura informàtica del tipus un servidor físic -una funció cap a una infraestructura virtual del tipus un servidor físic -varis servidors virtual -vàries funcions. Analitzarem l’estat actual de l’empresa, servidors i funcions, adquirirem el hardware necessari i farem la conversió de tots els seus servidors cap a una nova infraestructura virtual.Faig especial atenció a les explicacions de perquè utilitzo una opció i no un altre i també procuro sempre donar vàries opcions. Igualment remarco en quadres verds observacions a tenir en compte complementàries al que estic explicant en aquell moment, i en quadres vermells temes en els que s’ha de posar especial atenció en el moment en que es fan. Finalment, un cop feta la conversió, veurem els molts avantatges que ens ha reportat aquesta tecnologia a nivell de fiabilitat, estabilitat, capacitat de tolerància a errades, capacitat de ràpid desplegament de noves màquines, capacitat de recuperació del sistema i aprofitament de recursos físics.

Arithmetical problems in number fields, abelian varieties and modular forms

Number theory, a fascinating area in mathematics and one of the oldest, has experienced spectacular progress in recent years. The development of a deep theoretical background and the implementation of algorithms have led to new and interesting interrelations with mathematics in general which have paved the way for the emergence of major theorems in the area. This report summarizes the contribution to number theory made by the members of the Seminari de Teoria de Nombres (UB-UAB-UPC) in Barcelona. These results are presented in connection with the state of certain arithmetical problems, and so this monograph seeks to provide readers with a glimpse of some specific lines of current mathematical research.

Predicting the potential for lightning activity in mediterranean storms based on the WRF model dynamic and microphysical fields

A new parameter is introduced: the lightning potential index (LPI), which is a measure of the potential for charge generation and separation that leads to lightning flashes in convective thunderstorms. The LPI is calculated within the charge separation region of clouds between 0 C and 20 C, where the noninductive mechanism involving collisions of ice and graupel particles in the presence of supercooled water is most effective. As shown in several case studies using the Weather Research and Forecasting (WRF) model with explicit microphysics, the LPI is highly correlated with observed lightning. It is suggested that the LPI may be a useful parameter for predicting lightning as well as a tool for improving weather forecasting of convective storms and heavy rainfall.

Modelling of weather radar echoes from anomalous propagation using a hybrid parabolic equation method and NWP model data

Contamination of weather radar echoes by anomalous propagation (anaprop) mechanisms remains a serious issue in quality control of radar precipitation estimates. Although significant progress has been made identifying clutter due to anaprop there is no unique method that solves the question of data reliability without removing genuine data. The work described here relates to the development of a software application that uses a numerical weather prediction (NWP) model to obtain the temperature, humidity and pressure fields to calculate the three dimensional structure of the atmospheric refractive index structure, from which a physically based prediction of the incidence of clutter can be made. This technique can be used in conjunction with existing methods for clutter removal by modifying parameters of detectors or filters according to the physical evidence for anomalous propagation conditions. The parabolic equation method (PEM) is a well established technique for solving the equations for beam propagation in a non-uniformly stratified atmosphere, but although intrinsically very efficient, is not sufficiently fast to be practicable for near real-time modelling of clutter over the entire area observed by a typical weather radar. We demonstrate a fast hybrid PEM technique that is capable of providing acceptable results in conjunction with a high-resolution terrain elevation model, using a standard desktop personal computer. We discuss the performance of the method and approaches for the improvement of the model profiles in the lowest levels of the troposphere.

Evapotranspiração real de uma cultura de laranja em produção num Latossolo Vermelho-Amarelo

A disponibilidade de água e de nutrientes no solo em épocas e quantidades apropriadas, associada às condições edáficas e climáticas, é fator de indiscutível relevância à produção das culturas. O objetivo do presente trabalho foi avaliar a evapotranspiração real de uma cultura de laranja, analisar sua variabilidade e verificar a influência deste processo de saída de água do solo na produtividade da cultura. O experimento foi realizado no município de Piracicaba (SP), num Latossolo Vermelho-Amarelo distrófico argissólico, e a evapotranspiração real foi avaliada pelo método do balanço de água no solo em 40 pontos correspondentes a 40 plantas de duas linhas adjacentes com 20 plantas cada. A cultura de laranja, plantada num espaçamento de 7 x 4 m (7 m entre linhas por 4 m entre plantas na linha), tinha 11 anos de idade. Em cada ponto, localizado na projeção da copa (2 m do tronco) de cada uma das 40 plantas ao longo da linha, foram instalados um tubo de Al até à profundidade de 1,2 m para acesso de uma sonda de nêutrons e três tensiômetros às profundidades de 1,0, 1,1 e 1,2 m. A variação da armazenagem de água no solo foi determinada a partir de leituras semanais da sonda de nêutrons. A precipitação pluvial, medida por meio de um pluviômetro com aquisição automática de dados, foi considerada normal para o período monitorado. A drenagem interna e a ascensão capilar foram estimadas pela equação de Darcy-Buckingham, a partir de leituras diárias dos três tensiômetros e da condutividade hidráulica determinada na profundidade de controle (1,1 m) em função do potencial mátrico pelo método do perfil instantâneo. A irrigação e os deflúvios foram inexistentes e a evapotranspiração real da cultura foi calculada pela diferença entre a variação de armazenagem e a soma algébrica dos outros processos avaliados. O balanço foi efetuado durante um ciclo anual da cultura de laranja, dividido em 14 períodos. Nesses 14 períodos de monitoramento, a evapotranspiração real foi analisada com base nos métodos da estatística descritiva e exploratória de dados, obtendo-se um coeficiente de variação médio desses 14 períodos de 16 %. Foi de 1.271 mm a evapotranspiração real anual desta comunidade de plantas cujos valores diários variaram de 0,4 a 8,4 mm. A eficiência de utilização da água ou a razão entre a produtividade e a evapotranspiração real por planta durante o período monitorado variou de 1,57 a 4,52 kg m-3; verificou-se que as plantas com maior produção estavam entre aquelas com maior evapotranspiração real.

New combined serum creatinine and cystatin C quadratic formula for GFR assessment in children.

BACKGROUND AND OBJECTIVES: The estimated GFR (eGFR) is important in clinical practice. To find the best formula for eGFR, this study assessed the best model of correlation between sinistrin clearance (iGFR) and the solely or combined cystatin C (CysC)- and serum creatinine (SCreat)-derived models. It also evaluated the accuracy of the combined Schwartz formula across all GFR levels. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Two hundred thirty-eight iGFRs performed between January 2012 and April 2013 for 238 children were analyzed. Regression techniques were used to fit the different equations used for eGFR (i.e., logarithmic, inverse, linear, and quadratic). The performance of each model was evaluated using the Cohen κ correlation coefficient and the percentage reaching 30% accuracy was calculated. RESULTS: The best model of correlation between iGFRs and CysC is linear; however, it presents a low κ coefficient (0.24) and is far below the Kidney Disease Outcomes Quality Initiative targets to be validated, with only 84% of eGFRs reaching accuracy of 30%. SCreat and iGFRs showed the best correlation in a fitted quadratic model with a κ coefficient of 0.53 and 93% accuracy. Adding CysC significantly (P<0.001) increased the κ coefficient to 0.56 and the quadratic model accuracy to 97%. Therefore, a combined SCreat and CysC quadratic formula was derived and internally validated using the cross-validation technique. This quadratic formula significantly outperformed the combined Schwartz formula, which was biased for an iGFR≥91 ml/min per 1.73 m(2). CONCLUSIONS: This study allowed deriving a new combined SCreat and CysC quadratic formula that could replace the combined Schwartz formula, which is accurate only for children with moderate chronic kidney disease.

Summary of Real Estate Assessment, 2009

The most important aspect of property taxation is the concept that all property should be valued for tax purposes on a uniform basis so that the actual property tax burden can be distributed equitably among individual property owners. One of the most widely used and accepted methods of determining relative levels and uniformity of assessments is the assessment/sales ratio study. Such a study, in its most fundamental analysis, is the comparison of the assessed value of an individual property to its sale price. For example, a property assessed at $12,000 which sold for $26,000 would have an assessment/sales ratio of 46% ($12,000 ÷ $26,000). The purpose of this study is to provide assessment/sales ratio information that may be utilized by property tax administrators, local assessing officials, and interested taxpayers in examining the relative levels and uniformity of assessments throughout the State of Iowa. After further refinement, the study is one factor considered by the Director of Revenue in the biennial equalization of assessments.

Summary of Real Estate Assessment, 2008

The most important aspect of property taxation is the concept that all property should be valued for tax purposes on a uniform basis so that the actual property tax burden can be distributed equitably among individual property owners. One of the most widely used and accepted methods of determining relative levels and uniformity of assessments is the assessment/sales ratio study. Such a study, in its most fundamental analysis, is the comparison of the assessed value of an individual property to its sale price. For example, a property assessed at $12,000 which sold for $26,000 would have an assessment/sales ratio of 46% ($12,000 ÷ $26,000). The purpose of this study is to provide assessment/sales ratio information that may be utilized by property tax administrators, local assessing officials, and interested taxpayers in examining the relative levels and uniformity of assessments throughout the State of Iowa. After further refinement, the study is one factor considered by the Director of Revenue in the biennial equalization of assessments.