Introduction to the special issue on real world applications of intelligent tutoring systems

The idea behind creating this special issue on real world applications of intelligent tutoring systems was to bring together in a single publication some of the most important examples of success in the use of ITS technology. This will serve as a reference to all researchers working in the area. It will also be an important resource for the industry, showing the maturity of ITS technology and creating an atmosphere for funding new ITS projects. Simultaneously, it will be valuable to academic groups, motivating students for new ideas of ITS and promoting new academic research work in the area.

An��lise de risco em sequenciamento de actividades com restri����es de recursos

Mestrado em Engenharia Electrot��cnica e de Computadores. ��rea de Especializa����o em Sistemas e Planeamento Industrial.

Sistema de aquisi����o de dados em tempo real

Neste trabalho propus-me realizar um Sistema de Aquisi����o de Dados em Tempo Real via Porta Paralela. Para atingir com sucesso este objectivo, foi realizado um levantamento bibliogr��fico sobre sistemas operativos de tempo real, salientando e exemplificando quais foram marcos mais importantes ao longo da sua evolu����o. Este levantamento permitiu perceber o porqu�� da prolifera����o destes sistemas face aos custos que envolvem, em fun����o da sua aplica����o, bem como as dificuldades, cient��ficas e tecnol��gicas, que os investigadores foram tendo, e que foram ultrapassando com sucesso. Para que Linux se comporte como um sistema de tempo real, �� necess��rio configura-lo e adicionar um patch, como por exemplo o RTAI ou ADEOS. Como existem v��rios tipos de solu����es que permitem aplicar as caracter��sticas inerentes aos sistemas de tempo real ao Linux, foi realizado um estudo, acompanhado de exemplos, sobre o tipo de arquitecturas de kernel mais utilizadas para o fazer. Nos sistemas operativos de tempo real existem determinados servi��os, funcionalidades e restri����es que os distinguem dos sistemas operativos de uso comum. Tendo em conta o objectivo do trabalho, e apoiado em exemplos, fizemos um pequeno estudo onde descrevemos, entre outros, o funcionamento escalonador, e os conceitos de lat��ncia e tempo de resposta. Mostramos que h�� apenas dois tipos de sistemas de tempo real o ���hard��� que tem restri����es temporais r��gidas e o ���soft��� que engloba as restri����es temporais firmes e suaves. As tarefas foram classificadas em fun����o dos tipos de eventos que as despoletam, e evidenciando as suas principais caracter��sticas. O sistema de tempo real eleito para criar o sistema de aquisi����o de dados via porta paralela foi o RTAI/Linux. Para melhor percebermos o seu comportamento, estudamos os servi��os e fun����es do RTAI. Foi dada especial aten����o, aos servi��os de comunica����o entre tarefas e processos (mem��ria partilhada e FIFOs), aos servi��os de escalonamento (tipos de escalonadores e tarefas) e atendimento de interrup����es (servi��o de rotina de interrup����o - ISR). O estudo destes servi��os levou ��s op����es tomadas quanto ao m��todo de comunica����o entre tarefas e servi��os, bem como ao tipo de tarefa a utilizar (espor��dica ou peri��dica). Como neste trabalho, o meio f��sico de comunica����o entre o meio ambiente externo e o hardware utilizado �� a porta paralela, tamb��m tivemos necessidade de perceber como funciona este interface. Nomeadamente os registos de configura����o da porta paralela. Assim, foi poss��vel configura-lo ao n��vel de hardware (BIOS) e software (m��dulo do kernel) atendendo aos objectivos do presente trabalho, e optimizando a utiliza����o da porta paralela, nomeadamente, aumentando o n��mero de bits dispon��veis para a leitura de dados. No desenvolvimento da tarefa de hard real-time, foram tidas em aten����o as v��rias considera����es atr��s referenciadas. Foi desenvolvida uma tarefa do tipo espor��dica, pois era pretendido, ler dados pela porta paralela apenas quando houvesse necessidade (interrup����o), ou seja, quando houvesse dados dispon��veis para ler. Desenvolvemos tamb��m uma aplica����o para permitir visualizar os dados recolhidos via porta paralela. A comunica����o entre a tarefa e a aplica����o �� assegurada atrav��s de mem��ria partilhada, pois garantindo a consist��ncia de dados, a comunica����o entre processos do Linux e as tarefas de tempo real (RTAI) que correm ao n��vel do kernel torna-se muito simples. Para puder avaliar o desempenho do sistema desenvolvido, foi criada uma tarefa de soft real-time cujos tempos de resposta foram comparados com os da tarefa de hard real-time. As respostas temporais obtidas atrav��s do analisador l��gico em conjunto com gr��ficos elaborados a partir destes dados, mostram e comprovam, os benef��cios do sistema de aquisi����o de dados em tempo real via porta paralela, usando uma tarefa de hard real-time.

Direc����o de obra ��� obras de arte auto-estrada Transmontana ��� ��rea 3

Este relat��rio diz respeito ao trabalho desenvolvido em ambiente de est��gio acad��mico numa Empreitada compreendendo Obras de Arte Correntes e Obras de Arte Especiais inseridas em tra��ado actual do IP4 que est�� a ser transformado em Auto-Estrada. As Obras de Arte Correntes compreendem Passagens Superiores, Passagens Inferiores e Passagens superiores de N��. As Obras de Arte Especiais compreendem duas Pontes com v��os distintos. Todas as Obras de Arte referidas neste relat��rio contemplam uma solu����o mista de bet��o armado ���in situ��� e tabuleiros com vigas e pr��-lajes em bet��o pr��-fabricado. Al��m da descri����o de todas as actividades realizadas em bet��o armado ���in situ���, desde as funda����es at�� ao tabuleiro, descreve tamb��m a execu����o dos diversos tipos de trabalhos de acabamentos. Al��m das actividades de constru����o civil, �� efectuada uma descri����o das actividades a cujo processo de realiza����o est��o associados trabalhos de concep����o e desenvolvimento, como �� o caso dos cimbres. Este relat��rio faz uma descri����o abrangente das fun����es da Direc����o de Obra numa Empreitada de Obras de Arte, que para al��m da execu����o da obra, com todas as actividades que lhe s��o inerentes, compreende v��rias ��reas funcionais que fazem parte de uma empresa de constru����o civil, como a ��rea comercial, financeira, planeamento, aprovisionamento, controlo or��amental, gest��o contratual, gest��o de subempreitadas e gest��o da qualidade, ambiente e seguran��a.

Economic, environmental and mixed objective functions in non-linear process optimization using simulated annealing and tabu search

Screening of topologies developed by hierarchical heuristic procedures can be carried out by comparing their optimal performance. In this work we will be exploiting mono-objective process optimization using two algorithms, simulated annealing and tabu search, and four different objective functions: two of the net present value type, one of them including environmental costs and two of the global potential impact type. The hydrodealkylation of toluene to produce benzene was used as case study, considering five topologies with different complexities mainly obtained by including or not liquid recycling and heat integration. The performance of the algorithms together with the objective functions was observed, analyzed and discussed from various perspectives: average deviation of results for each algorithm, capacity for producing high purity product, screening of topologies, objective functions robustness in screening of topologies, trade-offs between economic and environmental type objective functions and variability of optimum solutions.

Probability distribution functions

This technical report describes the PDFs which have been implemented to model the behaviours of certain parameters of the Repeater-Based Hybrid Wired/Wireless PROFIBUS Network Simulator (RHW2PNetSim) and Bridge-Based Hybrid Wired/Wireless PROFIBUS Network Simulator (BHW2PNetSim).

Taxonomy of broker's functions in virtual enterprises

Not just with the emergence but also with the growing of the electronic market, that is, the growth of online suppliers of services and products and Internet users (potential consumers), the necessary conditions to the affirmation of the agile/virtual enterprises (A/VE) as a present and future enterprise organizational model are created. In this context, it is our understanding that the broker may have an important role in its development, namely, if the broker performs functions for the A/VE with better efficacy and efficiency. In this article, we will present first a revision of the broker���s models in a structured form. We present a taxonomy of possible broker���s functions for the broker���s actuation near the A/VE and then the classification of the literature broker���s models. This classification will permit an analysis of a broker���s model and establish a mainframe for our broker���s model according to the BM_Virtual Enterprise Architecture Reference Model (BM_VEARM).

Strength prediction of single- and double-lap joints by standard and extended finite element modelling

The structural integrity of multi-component structures is usually determined by the strength and durability of their unions. Adhesive bonding is often chosen over welding, riveting and bolting, due to the reduction of stress concentrations, reduced weight penalty and easy manufacturing, amongst other issues. In the past decades, the Finite Element Method (FEM) has been used for the simulation and strength prediction of bonded structures, by strength of materials or fracture mechanics-based criteria. Cohesive-zone models (CZMs) have already proved to be an effective tool in modelling damage growth, surpassing a few limitations of the aforementioned techniques. Despite this fact, they still suffer from the restriction of damage growth only at predefined growth paths. The eXtended Finite Element Method (XFEM) is a recent improvement of the FEM, developed to allow the growth of discontinuities within bulk solids along an arbitrary path, by enriching degrees of freedom with special displacement functions, thus overcoming the main restriction of CZMs. These two techniques were tested to simulate adhesively bonded single- and double-lap joints. The comparative evaluation of the two methods showed their capabilities and/or limitations for this specific purpose.

Delamination analysis of carbon fibre reinforced laminates: evaluation of a special step drill

Drilling of carbon fibre/epoxy laminates is usually carried out using standard drills. However, it is necessary to adapt the processes and/or tooling as the risk of delamination, or other damages, is high. These problems can affect mechanical properties of produced parts, therefore, lower reliability. In this paper, four different drills ��� three commercial and a special step (prototype) ��� are compared in terms of thrust force during drilling and delamination. In order to evaluate damage, enhanced radiography is applied. The resulting images were then computational processed using a previously developed image processing and analysis platform. Results show that the prototype drill had encouraging results in terms of maximum thrust force and delamination reduction. Furthermore, it is possible to state that a correct choice of drill geometry, particularly the use of a pilot hole, a conservative cutting speed ��� 53 m/min ��� and a low feed rate ��� 0.025 mm/rev ��� can help to prevent delamination.

Integration of e-learning systems with repositories of learning objects

This paper describes a communication model to integrate repositories of programming problems with other e-Learning software components. The motivation for this work comes from the EduJudge project that aims to connect an existing repository of programming problems to learning management systems. When trying to use the existing repositories of learning objects we realized that they are mainly specialized search engines and lack features for integration with other e-Learning systems. With this model we intend to clarify the main features of a programming problem repository, in order to enable the design and development of software components that use it. The two main points of this model are the definition of programming problems as learning objects and the definition of the core functions exposed by the repository. In both cases, this model follows the existing specifications of the IMS standard and proposes extensions to deal with the special requirements of automatic evaluation and grading of programming exercises. In the definition of programming problems as learning objects we introduced a new schema for meta-data. This schema is used to represent meta-data related to automatic evaluation that cannot be conveniently represented using the standard: the type of automatic evaluation; the requirements of the evaluation engine; or the roles of different assets - tests cases, program solutions, etc. In the definition of the core functions we used two different web services flavours - SOAP and REST - and described each function as an operation for each type of interface. We describe also the data types of the arguments of each operation. These data types consist mainly on learning objects and their identifications, but include also usage reports and queries using XQuery.

Multiple Roots of Systems of Equations by Repulsion Merit Functions

In this paper we address the problem of computing multiple roots of a system of nonlinear equations through the global optimization of an appropriate merit function. The search procedure for a global minimizer of the merit function is carried out by a metaheuristic, known as harmony search, which does not require any derivative information. The multiple roots of the system are sequentially determined along several iterations of a single run, where the merit function is accordingly modified by penalty terms that aim to create repulsion areas around previously computed minimizers. A repulsion algorithm based on a multiplicative kind penalty function is proposed. Preliminary numerical experiments with a benchmark set of problems show the effectiveness of the proposed method.

Smart Plastic Antibody Material for Hemoglobin Tailored by Silica Surface Imprinting and with Charged Binding Sites: Its use as Ionophore in Potentiometric Transduction

JORNADAS DE ELECTROQU��MICA E INOVA����O 2013

Fractional order describing functions

This paper addresses limit cycles and signal propagation in dynamical systems with backlash. The study follows the describing function (DF) method for approximate analysis of nonlinearities and generalizes it in the perspective of the fractional calculus. The concept of fractional order describing function (FDF) is illustrated and the results for several numerical experiments are analysed. FDF leads to a novel viewpoint for limit cycle signal propagation as time-space waves within system structure.