Construção de um robô trepador com locomoção através de rodas e adesão através de meios magnéticos

Mestrado em Engenharia Electrotécnica e de Computadores

Application of robust fixed point transformations for technological operation of robots

A robot’s drive has to exert appropriate driving forces that can keep its arm and end effector at the proper position, velocity and acceleration, and simultaneously has to compensate for the effects of the contact forces arising between the tool and the workpiece depending on the needs of the actual technological operation. Balancing the effects of a priori unknown external disturbance forces and the inaccuracies of the available dynamic model of the robot is also important. Technological tasks requiring well prescribed end effector trajectories and contact forces simultaneously are challenging control problems that can be tackled in various manners.

Simulador em Realidade Virtual para Aprendizagem da Física

A forma como aprendemos depende do contexto tecnológico e sociocultural que nos rodeia, actualmente a inclusão de tecnologia recente na sala de aula não é mais considerada opcional, mas sim uma necessidade pois a forma como o aluno aprende está em constante evolução. Tendo em atenção esta necessidade, foi desenvolvido no decorrer desta tese um simulador em realidade virtual que utiliza comandos/interfaces hápticos. O objectivo deste simulador é ensinar conceitos de física de forma interactiva. Os dispositivos hápticos permitem adicionar o sentido táctil ou de toque à interacção entre homem e máquina, permitindo assim aceder a novas sensações relativas ao seu uso nomeadamente com objectivos de aprendizagem. O simulador desenvolvido designado por “Forces of Physics” aborda três tipos de forças da física: forças de atrito, forças gravitacionais e forças aerodinâmicas. Cada tipo de força corresponde a um módulo do simulador contendo uma simulação individual em que são explicados conceitos específicos dessa força num ambiente visual estimulante e com uma interacção mais realista devido à inclusão do dispositivo háptico Novint Falcon. O simulador foi apresentado a vários utilizadores bem como á comunidade científica através de apresentações em conferências. A avaliação foi realizada com recurso a um questionário com dez perguntas, cinco de sobre aprendizagem e cinco sobre a utilização, tendo sido preenchido por 14 utilizadores. O simulador obteve uma boa recepção por parte dos utilizadores, tendo vários utilizadores expressado as suas opiniões sobre estado actual do simulador, do futuro do mesmo e da respectiva validade para uso na sala de aula.

Projeto de um centro de roda para veículo de competição

A presente tese surgiu da cooperação entre a empresa Semog Racing e o Instituto Superior de Engenharia do Porto, no âmbito da unidade curricular de DPEST, englobado no 2º ano do Mestrado de Engenharia Mecânica, ramo de Construções Mecânicas. Esta dissertação tem como objetivo principal, o projeto de um novo centro de roda para substituir o existente num veículo de competição da Semog Racing. Este centro deverá ser dimensionado para suportar o peso do veículo e os esforços transmitidos à roda. Pretende-se igualmente que o novo modelo apresente um design apelativo e um baixo custo de produção para poder vir ser a comercializado. Na primeira fase, será estudado o centro de roda original fornecido pela Semog Racing. Este estudo engloba a modelação do componente através do software SolidWorks® e uma fase de simulações para diferentes condições de carregamento. O estudo será complementado com a realização de ensaios experimentais para validação do modelo numérico. A segunda fase é dedicada ao desenvolvimento do novo modelo de centro de roda, focando as características mecânicas e o design. Este tem como base o estudo numérico realizado para a roda original, tendo sempre como objetivo final garantir que o novo centro de roda cumpra todos os requisitos. O caminho seguido no processo de otimização é suportado em simulações numéricas pelo método dos elementos finitos, o qual permite aferir quais os pontos críticos a corrigir. No final, será apresentado um novo modelo de centro de roda capaz de suportar as cargas previstas de serviço, que apresente um baixo custo de fabrico e design apelativo.

Discrete fractional order system vibrations

A theory of free vibrations of discrete fractional order (FO) systems with a finite number of degrees of freedom (dof) is developed. A FO system with a finite number of dof is defined by means of three matrices: mass inertia, system rigidity and FO elements. By adopting a matrix formulation, a mathematical description of FO discrete system free vibrations is determined in the form of coupled fractional order differential equations (FODE). The corresponding solutions in analytical form, for the special case of the matrix of FO properties elements, are determined and expressed as a polynomial series along time. For the eigen characteristic numbers, the system eigen main coordinates and the independent eigen FO modes are determined. A generalized function of visoelastic creep FO dissipation of energy and generalized forces of system with no ideal visoelastic creep FO dissipation of energy for generalized coordinates are formulated. Extended Lagrange FODE of second kind, for FO system dynamics, are also introduced. Two examples of FO chain systems are analyzed and the corresponding eigen characteristic numbers determined. It is shown that the oscillatory phenomena of a FO mechanical chain have analogies to electrical FO circuits. A FO electrical resistor is introduced and its constitutive voltage–current is formulated. Also a function of thermal energy FO dissipation of a FO electrical relation is discussed.

Projeto, Desenvolvimento e implementação de um Robô Voador de Inspiração Biológica

Este trabalho consiste no projeto, desenvolvimento e implementação de uma máquina voadora de inspiração biológica. Para a sua construção, é elaborado um estudo do voo nos seres biológicos de forma a obter alguma informação para o seu dimensionamento e é elaborada uma análise de projetos que utilizem as mesmas características de voo. Com os dados recolhidos neste estudo, é elaborado o projeto da máquina. Numa última fase, com recurso a materiais leves, é implementada uma máquina capaz de exercer as forças envolvidas no voo, força de propulsão e força de sustentação, e são elaborados estudos a fim de perceber quais os pontos fortes e os pontos fracos da mesma.

Localized Abdominal Idiopathic Lipodystrophy

Localized loss of subcutaneous tissue can occur after panniculitis, injections of corticosteroids and other drugs, or associated with infectious, autoimmune or neurologic diseases. The "idiopathic lipoatrophies" are a group of poorly characterized diseases, with focal disappearance of subcutaneous fat, and usually the thighs, abdomen or the ankles are affected. Three subtypes have been described based on clinical presentation: lipoatrophia semicircularis, annular lipoatrophy of the ankles and centrifugal lipodystrophy. We describe a 52-year-old female patient who developed a localized atrophy of the abdominal areas over a period of 3 months without any inflammatory signs over the evolution of the disease. The patient denied any previous local trauma or medication of any type. The atrophy stabilized, showing no progression over the last 6 years. The histopathological examination was normal except for the absence of subcutaneous fat, although the biopsy was taken down to the fascia. There was no clinical or serologic evidence of autoimmune diseases and laboratory testing for Borrelia burgdorferi infection was negative. Other causes of localized lipoatrophies were excluded and the final diagnosis was localized idiopathic lipodystrophy. Our patient is the second report on an abdominal lipodystrophy, with no previous inflammatory signs, absence of subcutaneous fat and no associated pathogenic factor. There is no established treatment for idiopathic lipodystrophy, and the lesions do not tend to resolve spontaneously.

Effective swimmer’s action during the grab start technique

The external forces applied in swimming starts have been often studied, but using direct analysis and simple interpretation data processes. This study aimed to develop a tool for vertical and horizontal force assessment based on the swimmers' propulsive and structural forces (passive forces due to dead weight) applied during the block phase. Four methodological pathways were followed: the experimented fall of a rigid body, the swimmers' inertia effect, the development of a mathematical model to describe the outcome of the rigid body fall and its generalization to include the effects of the inertia, and the experimental swimmers' starting protocol analysed with the inclusion of the developed mathematical tool. The first three methodological steps resulted in the description and computation of the passive force components. At the fourth step, six well-trained swimmers performed three 15 m maximal grab start trials and three-dimensional (3D) kinetic data were obtained using a six degrees of freedom force plate. The passive force contribution to the start performance obtained from the model was subtracted from the experimental force due to the swimmers resulting in the swimmers' active forces. As expected, the swimmers' vertical and horizontal active forces accounted for the maximum variability contribution of the experimental forces. It was found that the active force profile for the vertical and horizontal components resembled one another. These findings should be considered in clarifying the active swimmers' force variability and the respective geometrical profile as indicators to redefine steering strategies.

Caraterização das propriedades mecânicas de um adesivo estrutural de alta ductilidade

A tecnologia de ligação por adesivos estruturais tem vindo a ser utilizada ao longo de várias décadas, permitindo solucionar diversos problemas associados a técnicas chamadas "tradicionais" de ligação, como a soldadura, a rebitagem ou a ligação aparafusada. Esta é uma alternativa viável para substituir as ligações mecânicas, devido a diversos fatores como o menor peso estrutural, menor custo de fabricação e capacidade de união de diferentes materiais. O crescente recurso a materiais compósitos em diversas indústrias, nomeadamente a aeronáutica e naval, levaram ao consequente aumento da aplicação de ligações adesivas, por serem indicadas como forma de união destes materiais, onde é de enaltecer a sua elevada resistência à fadiga. Uma junta adesiva está maioritariamente sujeita a esforços de corte e arrancamento e portanto o conhecimento dos módulos de elasticidade à tração (E) ou corte (G) do adesivo, e ainda as resistências máximas à tração e ao corte, não é suficiente quando se pretende prever o comportamento da mesma. Na verdade, torna-se necessário abranger na análise a plastificação progressiva verificada nas juntas adesivas antes da rotura, sendo necessário o conhecimento de parâmetros tais como a taxa crítica de libertação de energia de deformação à tração (GIc) e corte (GIIc). Este trabalho pretende estudar um adesivo estrutural recentemente lançado no mercado, carecendo portanto da sua caracterização, para facilitar a previsão da resistência de estruturas adesivas ligadas com o mesmo. São 4 os ensaios a realizar: ensaios à tração de provetes em bruto, ensaios ao corte com a geometria Thick Adherend Shear Test (TAST), ensaios Double-Cantilever Beam (DCB) e ensaios End-Notched Flexure (ENF). Com a realização dos ensaios referidos, serão determinadas as propriedades mecânicas e de fratura à tração e ao corte, e serão fornecidos os parâmetros para a previsão da resistência de juntas adesivas com este adesivo por uma variedade de métodos, desde métodos analíticos mais expeditos até aos métodos numéricos mais avançados existentes atualmente. Os resultados foram de encontro aos disponibilizados pelo fabricante, sempre que estes se encontravam disponíveis, obtendo-se discrepâncias bastante reduzidas nos diversos parâmetros determinados.

O emprego de uma força de segurança de natureza militar nas missões de paz

The conflicts currently taking place around the world demand that the international intervention fits the intensity and extent of the threat. This is particularly important in post-conflict scenarios, leading to a greater participation of the Security Forces in those scenarios, in order to foster lasting peace, enforce the order and improve law enforcement services in those regions. The transition from armed conflict to peacekeeping may entail high risk situations and greater instability periods, so-called “intermediate situations”. Accordingly, in the face of persisting high volatility, a robust response is still required post-conflict. Therefore, it is appropriate to deploy Security Forces with military nature and status, the gendarmeries, which have training and response capabilities similar to Armed Forces in peacekeeping operations. Their double facet as police and military forces enables them to perform police duties in high risk and unsafe environments. In light of these features, the Portuguese gendarmerie, Guarda Nacional Republicana (GNR), is able to carry out tasks in these scenarios, which it has been doing through individual operatives or larger units. This dissertation focuses on the use of Security Forces of military nature in peacekeeping missions, in particular the Portuguese GNR, relying mostly on the inductive approach and using literature research, document analysis, interviews and statistics. After a brief description of international peacekeeping missions, we describe the contribution of Security Forces of a military nature in such operations. Then we introduce and analyse the GNR, focusing on its deployment in different kinds of peacekeeping operations, from its first participation in 1995 until today. We also report some reactions to the performance of GNR. Finally, we discuss whether there is indeed a unique role for this type of forces in international peacekeeping missions.

A intervenção dos orgãos de polícia criminal em sede de julgamento

Currently, Portugal assumes itself as a democratic rule of substantive law State, sustained by a legal system seeking the right balance between the guarantee of fundamental rights and freedoms constitutional foreseen in Portugal’s Fundamental Law and criminal persecution. The architecture of the penal code lies with, roughly speaking, a accusatory basic structure, “deliberately attached to one of the most remarkable achievements of the civilizational democratic progress, and by obedience to the constitutional commandment”, in balance with the official investigation principle, valid both for the purpose of prosecution and trial. Regarding the principle of non self-incrimination - nemo tenetur se ipsum accusare, briefly defined as the defendant’s right of not being obliged to contribute to the self-incrimination, it should be stressed that there isn’t an explicit consecration in the Portuguese Constitution, being commonly accepted in an implicit constitutional prediction and deriving from other constitutional rights and principles, first and foremost, the meaning and scope of the concept of democratic rule of Law State, embedded in the Fundamental Law, and in the guidelines of the constitutional principles of human person dignity, freedom of action and the presumption of innocence. In any case, about the (in) applicability of the principle of the prohibition of self-incrimination to the Criminal Police Bodies in the trial hearing in Court, and sharing an idea of Guedes Valente, the truth is that the exercise of criminal action must tread a transparent path and non-compliant with methods to obtain evidence that violate the law, the public order or in violation of democratic principles and loyalty (Guedes Valente, 2013, p. 484). Within the framework of the penal process relating to the trial, which is assumed as the true phase of the process, the witness represents a relevant figure for the administration of criminal justice, for the testimonial proof is, in the idea of Othmar Jauernig, the worst proof of evidence, but also being the most frequent (Jauernig, 1998, p. 289). As coadjutant of the Public Prosecutor and, in specific cases, the investigating judge, the Criminal Police Bodies are invested with high responsibility, being "the arms and eyes of Judicial Authorities in pursuing the criminal investigation..." which has as ultimate goal the fulfillment of the Law pursuing the defense of society" (Guedes Valente, 2013, p. 485). It is in this context and as a witness that, throughout operational career, the Criminal Police Bodies are required to be at the trial hearing and clarify the Court with its view about the facts relating to occurrences of criminal context, thus contributing very significantly and, in some cases, decisively for the proper administration of the portuguese criminal justice. With regards to the intervention of Criminal Police Bodies in the trial hearing in Court, it’s important that they pay attention to a set of standards concerning the preparation of the testimony, the very provision of the testimony and, also, to its conclusion. Be emphasized that these guidelines may become crucial for the quality of the police testimony at the trial hearing, thus leading to an improvement of the enforcement of justice system. In this vein, while preparing the testimony, the Criminal Police Bodies must present itself in court with proper clothing, to read before and carefully the case files, to debate the facts being judged with other Criminal Police Bodies and prepare potential questions. Later, while giving his testimony during the trial, the Criminal Police Bodies must, summing up, to take the oath in a convincing manner, to feel comfortable, to start well by convincingly answering the first question, keep an attitude of serenity, to adopt an attitude of collaboration, to avoid the reading of documents, to demonstrate deference and seriousness before the judicial operators, to use simple and objective language, to adopt a fluent speech, to use nonverbal language correctly, to avoid spontaneity responding only to what is asked, to report only the truth, to avoid hesitations and contradictions, to be impartial and to maintain eye contact with the judge. Finally, at the conclusion of the testimony, the Criminal Police Bodies should rise in a smooth manner, avoiding to show relief, resentment or satisfaction, leaving a credible and professional image and, without much formality, requesting the judge permission to leave the courtroom. As final note, it’s important to stress that "The intervention of the Police Criminal Bodies in the trial hearing in Court” encloses itself on a theme of crucial importance not only for members of the Police and Security Forces, who must welcome this subject with the utmost seriousness and professionalism, but also for the proper administration of the criminal justice system in Portugal.

THE EFECTS OF SETTLEMENT ON THE PREVALENCE OF AscarisINFECTION IN TWO AMERINDIAN POPULATIONS OF THE BRAZILIAN AMAZON

Studies were made of the intestinal parasites of Amerindian populations of the Uaupes River basin of Brazil. Three groups were sampled: 1) Tukano fisher-agriculturalists who live in permanent riverine villages; 2) Maku hunter-horticulturalists who live in close contact with the Tukano fishing villages; and 3) Maku who inhabit the forest interior and have little contact with permanent settlements. Fecal samples were collected from 498 individuals of which 220 were from the first group, 135 from de second and 143 from the third. The samples were analyzed by means of microflotation and centrifugal sedimentation. A total of 18 protozoan and helminth species were recorded based on the presence of cysts or eggs. These included five nematode species that could not be identified. The three common pathogenic nematodes were found to be prevalent: the hookworm, Necator americanus(96%); the whipworm, Trichuris trichiura(77%) and the large roundworm, Ascaris lumbricoides(75%). The prevalence of Ascarisamong the villages was found to vary from 56 to 100%. Individuals living in, or associated with, permanent settlements had higher prevalence and intensity rates than those living in the nomadic hunter-gatherer way. This is shown to be directly related to fecal contamination of the environment in and around permanent settlements. The prevalence of Ascarisin a population can be used as an indicator of such environmental contamination.

Antibacterial properties of fibrous stents coated with silver oxide nanocoatings

Stents are rigid and perforated tubular structures, which are inserted into blood vessels in order to prevent or inhibit the constriction of blood flow, restoring the normal blood flow, when blood vessels are clogged, being used in 70% of angioplasties. These medical devices assume great importance in the treatment of cardiovascular diseases (CVD) which are the leading cause of death worldwide. In the European Union CVD account for 40% of deaths and assume an estimated annual cost of 196 billion euros[1]. Stents must possess certain requirements, in order to, adequately, perform its function, such as biocompatibility (so that its use does not c ause damage on the health of its user), mechanical strength, radiopacity (so that it is easy to view), longitudinal flexibility, ease of handling, corrosion resistance and having high strength and high radial expansion ability to recover. Stents can be made of different materials, but metals, particularly stainless steel, are the most common. However, metallic stents present several dRawbacks such as corrosion and restenosis, leading to health complications for the patient, or even death. In order to minimize these disadvantages, new materials, like fibrous materials, have been used [2]. Monofilaments present high potential for stents development because, in addition to its biocompatibility, these materials allow the application of various surface treatments, such as antibacterial coatings. Furthermore, monofilament exhibit excellent mechanical properties, like greater stiffness and good results when subjected to compression, tensile and bending forces, since these forces will be directly supported by the monofilament [3]. To minimize the reaction of the human body and Limit the adhesion of microorganisms to the stent surface, some coatings have been developed, including the use of novel metals with antimicrobial properties, like silver. The main objective of this study was the development of fibrous stents, incorporation of silver oxide nanocoating. For the development of the stent, polyester monofilaments with 0.27mm of diameter were used in braiding technology, with a mandrel diameter of 6mm and a braiding angle of 35⁰. The mechanical behaviour of the stent were evaluated by mechanical testing under longitudinal and radial compression, bending. The results of compressive strength tests are according with value from literature: 1.13 to 2.9 N for radial compression and 0. 16-5.28N to longitudinal compression. From literature is also possible to verify that stents must present 75% of unchanged diameter during the bending test and must possess a porosity between 70% and 80% [4]. The produced polyester stent presents values of 1.29N for radial compression, 0.23N for longitudinal compression, 80% of porosity and 85.5% of unchanged diameter, during bending tests. For the antibacterial functionalization, silver oxide nanocoatings were prepared, through reactive magnetron g, with an Ag target in an Ar +O2 atmosphere. In order to evaluate the nanostructure and morphology of the coatings, d ifferent technique s like X-ray diffraction (XRD), scanning electron microscopy (SEM) and and X- ray photoelectron spectroscopy (XPS were used. From the analyses of XRD it is possible to verify that the peaks corresponds to planes of Ag2 O and MATERIAIS 2015 Porto, 21-23 June, 2015 characterize a cubic phase. The presence of Ag2 O is corroborated by XPS spectrum, where it is possible to observe silver, not only, in oxide state, but a lso in mettalic state, and it is possible to verify the presence of silver clusters, confirmed by SEM analysis. Films’ roughness and topography, parameters influencing the wettability of the surface and microorganism adhesion, were measured by Atomic Force Microscopy (AFM), and it was observed that the roughness is very low (under 10 nm). Coatings’ hydrophobicity and surface tension parameters were determined by contact angle measurement, and it was verified the hydrophobic behavior of the coatings. For antibacterial tests were used Staphylococcus epidermidis strain (IE186) and Staphylococcus aureus(ATCC 6538), and halo inhibition zone tests were realized. Ag+release rates were studied by means of inductively coupled plasma mass spectrometry (ICP -MS). The obtained results suggest that silver oxide coatings do not modify significantly surface properties of the substrate, like hydrophobicity and roughness, and present antimicrobial properties for both bacteria used.

Pervasive business intelligence: a marketing intelligence framework proposal

Doctoral Thesis in Information Systems and Technologies Area of Information Systems and Technology

Definition of multibody system

This chapter presents a general view of multibody system concept and definition by describing the main features associated with spatial systems. The mechanical components, which can be modeled as rigid or flexible, are constrained by kinematic pair of different types. Additionally, the bodies can be actuated upon by force elements and external forces due to interaction with environment. This chapter also presents some examples of application of multibody systems that can include automotive vehicles, mechanisms, robots and biomechanical systems.