Model reference adaptive control of robots

This project presents the results of controlling two types of robots using new Command Generator Tracker (CGT) based Direct Model Reference Adaptive Control (MRAC) algorithms. Two mathematical models were used to represent a single-link, flexible joint arm and a Unimation PUMA 560 arm; and these were then controlled in simulation using different MRAC algorithms. Special attention was given to the performance of the algorithms in the presence of sudden changes in the robot load. Previously used CGT based MRAC algorithms had several problems. The original algorithm that was developed guaranteed asymptotic stability only for almost strictly positive real (ASPR) plants. This condition is very restrictive, since most systems do not satisfy this assumption. Further developments to the algorithm led to an expansion of the number of plants that could be controlled, however, a steady state error was introduced in the response. These problems led to the introduction of some modifications to the algorithms so that they would be able to control a wider class of plants and at the same time would asymptotically track the reference model. This project presents the development of two algorithms that achieve the desired results and simulates the control of the two robots mentioned before. The results of the simulations are satisfactory and show that the problems stated above have been corrected in the new algorithms. In addition, the responses obtained show that the adaptively controlled processes are resistant to sudden changes in the load

Aprovechamiento del aceite de cocina usado en el Instituto Tecnológico de Costa Rica para la producción de biodiesel

Proyecto de Graduación (Licenciatura en Ingeniería Ambiental) Instituto Tecnológico de Costa Rica, Escuela de Química, 2013.El creciente aumento del consumo de combustibles fósiles y el aumento en su precio a nivel internacional han impulsado la búsqueda de nuevas alternativas para la sustitución de estos. El aceite de cocina usado surge como una opción para la producción de biodiesel. Este residuo en caso de ser mal manejado es sumamente dañino para el ambiente, en especial para las fuentes de agua. El Instituto Tecnológico de Costa Rica (ITCR), como institución emblemática del país, debe dar el ejemplo y aprovechar los residuos generados dentro de sus instalaciones para disminuir su impacto ambiental. Además de esto, contribuir en la formación de sus estudiantes tanto en el área ambiental, como en el desarrollo de posibles nuevos negocios. El propósito del trabajo es explorar la capacidad del ITCR de producir biodiesel a partir del aceite de cocina usado en el comedor institucional, que cumpla con las normas de calidad establecidas a nivel nacional y genere beneficios tanto educativos como económicos a la institución. De acuerdo con los resultados obtenidos, el biodiesel producido tuvo un alto rendimiento y los parámetros estudiados estuvieron en cumplimiento con lo dispuesto en la legislación nacional. Con base en esto, el proyecto demuestra potencial, sin embargo se debe lograr reducir los costos operativos y de infraestructura para garantizar que sea viable económicamente

Knowledge production in visual arts organizations : a case study on the triangle network

As Arjun Appadurai notes, globalization makes knowledge more valuable and more ephemeral (Appadurai, 2006), suggesting an urgent need to engage with the analysis of knowledge production between the realms of the local and the global. By looking at visual arts organizations from a curatorial perspective, the question will be how these institutions engage with the production of knowledge precisely in-between these realms – working independently focusing on the local context in which they operate and collaborating internationally through the network. For this purpose, the analysis will part from the Triangle Network, through which 40 visual arts organizations from different countries have collaborated with each other in varied ways over the last three decades. Three case studies will be considered in detail through interviews following the general interview guide approach and ethnographic analysis: HANGAR in Lisbon, Gasworks in London and 32° East in Kampala. Throughout the research, three means for the production of knowledge in these organizations are defined and elaborated on: mediation, representation and conviviality. Addressing the development from education towards mediation, the emphasis on the artistic process instead of the creation of a product, and the key element of the 'other' as a possibility for encounter, conversation and the sharing and production of knowledge, this inquiry tackles the existence of different kinds of knowledge(s) and the importance of their conservation and exploration in spaces dedicated to the visual arts such as VAOs.Tal como Arjun Appadurai sustenta, a globalização torna o conhecimento mais valioso e mais efémero (Appadurai, 2006), colocando em evidência a urgência no estudo da produção de conhecimento que ocorre entre a esfera local e global. A partir da análise de organizações ligadas às artes visuais numa perspectiva curatorial, esta investigação propõe explorar a produção de conhecimento que daí resulta, tendo em consideração que o trabalho destas instituições é independente e se desenvolve com foco no contexto local, mas em colaboração com a rede internacional à qual pertence. A partir da Triangle Network, através da qual 40 organizações de diferentes países têm colaborado ao longo das três últimas décadas das mais diversas formas, foram seleccionados três casos de estudo: o HANGAR em Lisboa, a Gasworks em Londres e a 32º East em Kampala. Seguindo uma metodologia etnográfica e baseada em entrevistas, serão exploradas três dinâmicas possíveis nas quais a produção de conhecimento ocorre: mediação, representação e convivialidade. Pretende-se abordar o desenvolvimento da educação com vista à mediação, dando ênfase não só ao processo criativo ao invés do produto da criação como também ao elemento do ‘outro’ que aqui é considerado crucial para a possibilidade de encontro, conversação, partilha e produção de conhecimento. Esta investigação visa explorar a ideia da existência de diferentes tipos de conhecimento, valorizando a sua conservação e exploração em espaços dedicados às artes visuais como as organizações de artes visuais, aqui referidas como VAOs (sigla do inglês visual arts organizations)

Interrelationship between Human Rights and Peace Two Mistaken Conceptions of Human Rights in both Islam and the West

The first mistaken conception is this. Some Muslim theorists argue that only God can proclaim what justice, right, and rights are; hence parliaments and other state institutions lack the sovereignty to create laws and to proclaim rights. They presume that Western states in their legislation and the UN in their Universal Declaration of Human Rights of 1948 claim such sovereignty. Many Western theorists share their view, differing only in the evaluation. But human rights imply that states must follow them and lack the sovereignty for legislation incompatible with them. The German constitution is explicit on this lack of human sovereignty. It declares in Art.1: “The following basic rights shall bind the legislature, the executive, and the judiciary as directly applicable law.” Hence, the idea of human rights implies that human rights and basic principles of legislation are valid not because states have declared them but because of their inherent qualities. It also implies that states are legitimate only if they conform to such basic principles and excludes the idea that the principles are legitimate because states or mankind have accepted them. Therefore, Western and Islam conceptions of law and sovereignty are less different than they seem. Second, it is generally accepted in Islam and the West that there is a right and even the duty of every human being to fight for justice and the protection of human rights. But there are two conceptions of such a fight both in Islam and the West. The model of the fight for human rights in the centralist conception is a bureaucracy that imposes its rules on the cases it administers. The model in the autonomous conception is a scientific community that solves its differences by principles developed in the community itself. اولین مفهوم اشتباه، اینکه برخی از نظریه‌پردازان مسلمان ادعا می‌کنند که تنها خداوند می‌تواند عدالت، حق و حقوق را تعیین کند؛ پس بدین ترتیب، پارلمان‌ها و دیگر نهادهای دولتی فاقد قدرت لازم برای تصویب قانون و اعلام حق هستند. آن‌ها همچنین بر این باورند که دولت‌های غربی در قانون گذاری‌ها و سازمان ملل در اعلامیة جهانی حقوق بشر 1948، ادعای چنین قدرتی داشته‌اند. بسیاری از نظریه‌پردازان غربی نیز نظراتی مشابه آن‌ها دارند و تنها وجه تفاوت آن‌ها در روش ارزیابی آن‌هاست. اما حقوق بشر نشان می‌دهد که دولت‌ها باید از آن پیروی کرده و هیچ قدرتی برای تصویب قوانینی مخالف آن‌ها ندارند. قانون اساسی آلمان در مورد این عدم قدرت قانون‌گذاری بشر به صراحت صحبت کرده است. بر اساس بند 1 آن «حقوق اساسی زیر به عنوان قوانینی که مستقیما باید اعمال شوند، مجلس قانون‌گذاری، اجرایی و قوة قضاییه را به یکدیگر متصل می کند.» از این رو، ایدة حقوق بشر نشان دهنده آن است که حقوق بشر و اصول اساسی قانون‌گذاری نه به خاطر اینکه دولت‌ها آن‌ها را اعلام می‌کنند بلکه به خاطر ماهیت ذاتی آن‌ها دارای اعتبار ند. این مسئله همچنین نشان می‌دهد که دولت‌ها تنها زمانی مشروع خواهند بود که با این اصول اساسی مطابقت داشته و این ایده را رد می‌کند که مشروعیت این اصول به دلیل تایید آن‌ها توسط دولت‌ها یا انسان‌ها است. بنابراین، مفاهیم غرب و اسلام از قانون و قدرت کمتر از آنچه به نظر می‌رسد، تفاوت دارند. دوم اینکه به طور کلی در اسلام و غرب پذیرفته شده است که حق و حتی وظیفه هر انسانی است که برای عدالت و حمایت از حقوق بشر مبارزه کند. اما اسلام و غرب هر کدام برداشت متفاوتی از مفهوم مبارزه دارند. مدل مبارزه برای حقوق بشر در دیدگاه اسلامی، یک دیوان‌سالاری است که قوانین آن بر نهادهای تابعه آن اعمال می‌شود. اما در غرب مبارزه برای حقوق بشر از طریق یک جامعه علمی صورت می‌گیرد که اختلافات خود را با اصولی که در خود آن جامعه ایجاد شده است، حل می کند

Universities and community-based research in developing countries: community voice and educational provision in rural Tanzania

The main focus of recent research on the community engagement role of universities has been in developed countries, generally in towns and cities and usually conducted from the perspectives of universities rather than the communities with which they engage. The purpose of this paper is to investigate the community engagement role of universities in the rural areas of developing countries, and its potential for strengthening the voice of rural communities. The particular focus is on the provision of primary and secondary education. The paper is based on the assumption that in order for community members to have both the capacity and the confidence to engage in political discourse for improving educational capacity and quality, they need the opportunity to become involved and well-versed in the options available, beyond their own experience. Particular attention is given in the paper to community-based research (CBR). CBR is explored from the perspectives of community members and local leaders in the government-community partnerships which have responsibility for the provision of primary and secondary education in rural Tanzania. The historical and policy background of the partnerships, together with findings from two case studies, provide the context for the paper

Grey and white matter correlates of recent and remote autobiographical memory retrieval:Insights from the dementias

The capacity to remember self-referential past events relies on the integrity of a distributed neural network. Controversy exists, however, regarding the involvement of specific brain structures for the retrieval of recently experienced versus more distant events. Here, we explored how characteristic patterns of atrophy in neurodegenerative disorders differentially disrupt remote versus recent autobiographical memory. Eleven behavioural-variant frontotemporal dementia, 10 semantic dementia, 15 Alzheimer's disease patients and 14 healthy older Controls completed the Autobiographical Interview. All patient groups displayed significant remote memory impairments relative to Controls. Similarly, recent period retrieval was significantly compromised in behavioural-variant frontotemporal dementia and Alzheimer's disease, yet semantic dementia patients scored in line with Controls. Voxel-based morphometry and diffusion tensor imaging analyses, for all participants combined, were conducted to investigate grey and white matter correlates of remote and recent autobiographical memory retrieval. Neural correlates common to both recent and remote time periods were identified, including the hippocampus, medial prefrontal, and frontopolar cortices, and the forceps minor and left hippocampal portion of the cingulum bundle. Regions exclusively implicated in each time period were also identified. The integrity of the anterior temporal cortices was related to the retrieval of remote memories, whereas the posterior cingulate cortex emerged as a structure significantly associated with recent autobiographical memory retrieval. This study represents the first investigation of the grey and white matter correlates of remote and recent autobiographical memory retrieval in neurodegenerative disorders. Our findings demonstrate the importance of core brain structures, including the medial prefrontal cortex and hippocampus, irrespective of time period, and point towards the contribution of discrete regions in mediating successful retrieval of distant versus recently experienced events

Long-term coding of personal and universal associations underlying the memory web in the human brain

Neurons in the medial temporal lobe (MTL), a critical area for declarative memory, have been shown to change their tuning in associative learning tasks. Yet, it is unclear how durable these neuronal representations are and if they outlast the execution of the task. To address this issue, we studied the responses of MTL neurons in neurosurgical patients to known concepts (people and places). Using association scores provided by the patients and a web-based metric, here we show that whenever MTL neurons respond to more than one concept, these concepts are typically related. Furthermore, the degree of association between concepts could be successfully predicted based on the neurons’ response patterns. These results provide evidence for a long-term involvement of MTL neurons in the representation of durable associations, a hallmark of human declarative memory