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Gulcan, Ege. "Flexible and Lightweight Cryptographic Engines for Constrained Systems." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/52913.
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There is a significant effort in building lightweight
cryptographic operations, yet the proposed solutions are typically
single purpose modules that can only provide a fixed functionality. However, flexibility is an important aspect of cryptographic designs where a module can perform multiple operations with different configurations. In this work, we combine flexibility with lightweight designs and propose two cryptographic engines based on the SIMON block cipher. The first proposed engine is the Flexible SIMON, which can execute all configurations of SIMON thus enables an adaptive security with variable key sizes. Our second proposed implementation is BitCryptor, a bit-serialized Compact Crypto Engine that can perform symmetric key encryption, hash computation and pseudo-random-number-generation. The implementation results on a Spartan-3 s50 FPGA show that the proposed engines occupies 90 and 95 slices respectively, which are more compact than the majority of their single purpose counterparts. Therefore, these engines are suitable cryptographic blocks for resource-constrained systems.Master of Science
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Barrère, Killian. "Architectures de Transformer légères pour la reconnaissance de textes manuscrits anciens." Electronic Thesis or Diss., Rennes, INSA, 2023. http://www.theses.fr/2023ISAR0017.
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En reconnaissance d’écriture manuscrite, les architectures Transformer permettent de faibles taux d’erreur, mais sont difficiles à entraîner avec le peu de données annotées disponibles. Dans ce manuscrit, nous proposons des architectures Transformer légères adaptées aux données limitées. Nous introduisons une architecture rapide basée sur un encodeur Transformer, et traitant jusqu’à 60 pages par seconde. Nous proposons aussi des architectures utilisant un décodeur Transformer pour inclure l’apprentissage de la langue dans la reconnaissance des caractères. Pour entraîner efficacement nos architectures, nous proposons des algorithmes de génération de données synthétiques adaptées au style visuel des documents modernes et anciens. Nous proposons également des stratégies pour l’apprentissage avec peu de données spécifiques, et la réduction des erreurs de prédiction. Nos architectures, combinées à l’utilisation de données synthétiques et de ces stratégies, atteignent des taux d’erreur compétitifs sur des lignes de texte de documents modernes. Sur des documents anciens, elles parviennent à s’entraîner avec des nombres limités de données annotées, et surpassent les approches de l’état de l’art. En particulier, 500 lignes annotées sont suffisantes pour obtenir des taux d’erreur caractères proches de 5%Transformer architectures deliver low error rates but are challenging to train due to limited annotated data in handwritten text recognition. We propose lightweight Transformer architectures to adapt to the limited amounts of annotated handwritten text available. We introduce a fast Transformer architecture with an encoder, processing up to 60 pages per second. We also present architectures using a Transformer decoder to incorporate language modeling into character recognition. To effectively train our architectures, we offer algorithms for generating synthetic data adapted to the visual style of modern and historical documents. Finally, we propose strategies for learning with limited data and reducing prediction errors. Our architectures, combined with synthetic data and these strategies, achieve competitive error rates on lines of text from modern documents. For historical documents, they train effectively with minimal annotated data, surpassing state-ofthe- art approaches. Remarkably, just 500 annotated lines are sufficient for character error rates close to 5%
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Kwong, Edmund Ming Yip. "Lightweight plywood construction assembly : a lightweight approach to the elegant utilitarian form." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/49734.
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Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 2009.Word "construction" in title purposely crossed-out on title page.
Includes bibliographical references (leaf 81).
What will be the fundamental aspect and concern of today's good design? As global energy reserves deplete over the coming decades, a strategy of reduced consumption will be essential to the production of furniture and architecture, alike. A lightweight design strategy is a way for designers to participate in reducing the environmental footprint of everyday objects. We are witnessing a Paradigm shift in design and the decorative arts of a magnitude not seen since the Modernist movement in the early 20th century. A design style embraces the combination of sustainability with building production. Today we recognizes that our resources are finite and that careful consideration should be given to the building process. Since ecological concern of materials become one of the foremost issues of today's building industry, For this project, I developed a lightweight and low-cost framing system that is collapsible and easy to assemble. My goal is to create compelling designs in the hope they will inspire people to choose sustainable design over safer and more traditional designs. Making building from thin bent plywood yields 9-10 times more usable wood from a log than making a building from hardwood lumber During the production of plywood, only 15 percent of the wood from a log is lost to waste. On the other hand , the average waste it takes to make a finished solid wood frame building is 1.5 times more wood than is used in the building itself! Bent plywood has been utilized by a mere handful of designer, most notably Alvar Aalto and Charles and Ray Eames, but the application of this material remained in furniture scale.
(cont.) Since the creative potential of this material is still largely unexplored. My motivation is to extend the application of this very particular thin material-plywood.
by Edmund King Yip Kwong.
M.Arch.
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Bonnemaison, Sarah. "Lightweight structures in urban design." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/71363.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Architecture, 1985.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH.
Includes bibliographical references (leaves 83-84).
Lightweight architecture questions how we architects think about the environment. It has qualities which complement "mainstream" buildings. This thesis will explore these qualities and will propose that this architecture is rooted in the modern sensibility and suggests an attitude towards the environment that is needed in our cities. Lightweight architecture is concerned with optimal and, particularly, parsimonious use of materials and effort. Much lightweight architecture is tensile as structures loaded in tension use the least amount of material. Now that modern technology and materials have opened up possibilities· in research and application, much of the research has been done and is no longer the exclusive realm of trained engineers. The question of application of this technology remains -- this is up to the architects. The style of lightweight architecture can be looked at in terms of aesthetic, the process by which one develops its forms and the way of thinking from which it arises. The aesthetic of lightweight architecture enriches the traditional aesthetic notion familiar to us (symmetry, proportion and balance) with the more elusive notions of dynamic symmetry, relative harmony and equilibrium. Form-finding is an experimental process of trial and error. It stems not only from the scientific discipline of static, but from other disciplines , explored from without. In this way, unexpected combinations appear. Complementing static research into the minimal use of materials, vernacular constructions and biology have been used for a greater understanding of parsimony in building. The "logic of reasoning" refers to a creator's conception of the world in which one creates. The designers of lightweight architecture believe in a world not of specialization and analysis, but of creation and adaption, an ecological view of the world. Because the process of creation is more important that the resultant form, the syntactics of structural and formal assembly takes precedence on an analogical basis for form-finding.The second section of this thesis explores lightweight architecture in the city. The current trend of placing lightweight buildings in parks rejects the possibilities of lightweight architecture can offer the city. Many architects see a conflict in the juxtaposition of lightweight buildings against traditional load-bearing urban "fabric". Lightweight architecture implies notions of boundary and mutability that are contrary to these same notions as represented in industrial cities. Being ephemeral, mobile and adaptable, this architecture, by its unboundedness, forces us to re-assess our notion of boundary. Lightweight architecture, allows for a rapid adaption of buildings in the city to climatic change and for the periodic gathering of festivals and markets. The adaptive, mutable qualities lightweight architecture can bring to the city are particularly valuable for urban public spaces. This architecture allows for human engagement with the environment and with each other. The load-bearing wall and its function in the city -- the separation of one activity from another and the definition of privacy -- has been radically redefined by the advent of the glass curtain wall and the telephone. This process has left us with ambiguous urban "public" spaces not much used by the public yet not truly private. Re-introducing a mobile, lightweight ephemeral architecture into post-industrial cities is a desire to implement certain socio-political ideas about city culture and simultaneously make places where those policies are lived.
by Sarah Bonnemaison.
M.S.
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Mahmoud, Tariq [Verfasser]. "Lightweight Semantic-enabled Enterprise Service-Oriented Architecture / Tariq Mahmoud." Aachen : Shaker, 2013. http://d-nb.info/1050345827/34.
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Shepherd, Robert G. "A Bluetooth-based communications architecture for lightweight mobile robots." Thesis, Bangor University, 2006. https://research.bangor.ac.uk/portal/en/theses/a-bluetooth--based-communications-architecture-for-lightweight-mobil-robots(edbc4538-80d0-48e3-ad9c-c7476dd05cad).html.
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Rajakaruna, A. (Archana). "Lightweight edge-based networking architecture for low-power IoT devices." Master's thesis, University of Oulu, 2019. http://jultika.oulu.fi/Record/nbnfioulu-201906072483.
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Abstract. The involvement of low power Internet of Things (IoT) devices in the Wireless Sensor Networks (WSN) allow enhanced autonomous monitoring capability in many application areas. Recently, the principles of edge computing paradigm have been used to cater onsite processing and managing actions in WSNs. However, WSNs deployed in remote sites require human involvement in data collection process since internet accessibility is still limited to population dense areas. Nowadays, researchers propose UAVs for monitoring applications where human involvement is required frequently. In this thesis work, we introduce an edge-based architecture which create end-to-end secure communication between IoT sensors in a remote WSN and central cloud via UAV, which assist the data collection, processing and managing procedures of the remote WSN. Since power is a limited resource, we propose Bluetooth Low Energy (BLE) as the communication media between UAV and sensors in the WSN, where BLE is considered as an ultra-low power radio access technology. To examine the performance of the system model, we have presented a simulation analysis considering three sensor nodes array types that can realize in the practical environment. The impact of BLE data rate, impact of speed of the UAV, impact of distance between adjacent sensors and impact of data generation rate of the sensor node have been analysed to examine the performance of system. Moreover, to observe the practical functionality of the proposed architecture, prototype implementation is presented using commercially available off-the-shelf devices. The prototype of the system is implemented assuming ideal environment.
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Garbis, Leonidia Maria. "Lightweight concrete : investigations into the production of natural fiber reinforcement." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82261.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Architecture, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 34).
The purpose of this study is to investigate the benefits of adding natural fiber tensile reinforcement to aerated concrete. Concrete is a great composite material which can be created in various proportions and with various materials to alter its strength, density and porosity, amongst other properties. Concrete which is used commonly in construction of columns, beams, and slabs acts well in compression but fails under tension. The common solution is to reinforce the structure in areas where it experiences tension with steel. There are other materials besides steel which also take tension well. Natural fibers for example come in various strengths and types and would create lighter and perhaps more sustainable beam designs. Natural fibers have been used for their availability, workability, and high tensile strengths for centuries. This research discovers how the natural fibers distribute within the mixture and how they affect the aeration of the concrete, as well as how they affect the strength. Multiple samples are cured with different fiber types and in different proportions within the mixture. Furthermore, similar experimentation is conducted to discover an ideal ratio of aggregate to aerated concrete mix. The aggregate gives the concrete greater strength and economy, but could negatively affect the aeration. The various concrete mixes are poured and allowed to cure to maximum strength before indirect tensile tests and compression tests are conducted. The effects of creating smooth aerated concrete molds are also investigated. All experiments conducted are precursory to an ultimate tensile reinforced aerated concrete beam design with an aggregate mix and smooth surfaces.
by Leonidia Maria Garbis.
S.B.
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Cohan, Lucy Elizabeth. "Integrated modeling to facilitate control architecture design for lightweight space telescopes." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40307.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 161-167).
The purpose of this thesis it to examine the effects of utilizing control to better meet performance and systematic requirements of future space telescopes. New telescope systems are moving toward tighter optical performance requirements with lower mass and cost, creating an implicit conflict for currently designed systems. Therefore, new technology and telescope types must be developed and implemented, and a key to lightweight systems is the addition of controls. This thesis uses an integrated modeling technique to examine a large tradespace of space telescope systems. The analysis techniques includes finite element and dynamic disturbance analyses to determine the effects of various parameters on overall system performance metrics. In particular, this thesis will focus on the control system architecture for future space telescopes. As systems become less massive, more control is necessary to meet the performance requirements. Less massive systems have more flexibility, which degrades performance. Thus, this flexibility must be controlled to obtain adequate performance. However, the control also has a cost that must be considered.
(cont.) As the areal density of the mirror decreases, the cost due to mass decreases, but the cost due to control increases because more control is required to meet the requirements. Therefore, a balance between lightweight systems and control is sought to give the best overall performance. Additionally, there are many different types of control that could be used on the system, thus finding optimal combinations of controllers, sensors, actuators, and bandwidths is a daunting task. The integrated modeling technique allows the designer to examine the effects of structural parameters and requirements on the control system architecture and the performance metrics. The ability to determine favorable control system architectures early in the design process will allow new technologies to be pushed further, while still maintaining confidence that the system will perform as expected.
by Lucy Elizabeth Cohan.
S.M.
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Cooke, Timothy Graham. "Lightweight concrete : investigations into the production of variable density cellular materials." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78505.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 123-127).
This research focuses on the intersection between material composition and form in the development of a new type of concrete. As concrete is the most widely used building material in the world, innovation in this material has more potential to effect change in our built environment than innovation in any other. With the objective of minimizing raw material consumption and energy use, this work attempts to develop methods for creating a cellular lightweight concrete with variable density that can be cured at room temperature. Most aerated concretes traditionally require high temperature and high pressure curing; the goal of this research is to create a lower embodied energy product through the use of room temperature curing, while at the same time maximizing performance through variation of the density of the material through its section-essentially locating stronger material where it is needed. This more durable and versatile concrete product will be able to compete with traditional lightweight concretes, which provide benefits such as insulation, as well as normal-weight concrete, which is harder and stronger. The research aims to capitalize on the inherent heterogeneity of the material by producing a substance whose internal properties can be varied based on the needs of a specific part of a building. I am interested in replacing the concept of the "assembly" of materials to gain a desired function with a more unitary concept: the manipulation of a single material to meet a building's multiple needs. A desired outcome of the work is to reconceive how we put buildings together, not as assemblies of discrete elements but as monolithic yet malleable wholes.
by Timothy Graham Cooke.
S.M.
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McCluskey, Keith V. (Keith Vincent) 1971. "Portable housing : an exploration into lightweight housing for remote scientific research." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/68813.
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Thesis (M.Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 2002.Includes bibliographical references (leaves 51-53).
This thesis proposes the design of portable housing for use in scientific research applications in remote locations. Currently, remote research is conducted from tents or other portable shelters. Larger, more hospitable structures are often too heavy or bulky to carry to these locations. This thesis proposes a shelter that is lightweight, packable, and biodegradable. The shelter is constructed of cardboard panels, which can easily be left to decompose in most environments, or can be recycled after use. The shelter is meant to last only for one season (up to six months), and then be recycled. The shelter requires upkeep on a weekly basis to maintain its waterproofness, and responds to the climatic changes of its surroundings by opening or closing as temperature and conditions warrant. It is, hopefully, much more livable than a tent.
This thesis explores a method of studying the city of Banaras, located in the north-central part of India, through Satyajit Ray's movie Aparajito (1957). This method attempts to disengage the all-subsuming sacred aura of Banaras to reveal underlying historic and cultural formations. As the inter-play between the movie and the city excavates peripheral discourses engrained in the film, these discourses are further subjected to the aesthetic parameters of Ray. His engagement with traditional practices and the psychology of individuals re-structure different cultural and spatial aspects of Banaras. Through the simultaneously engagement with the aesthetics of the film and Banaras multiple readings are formed. This process of re-aestheticizing Banaras reaches its conclusion in are-edited 'Aparajito'. By inhabiting the film I attempt to reveal the manner in which Ray positions and contextualizes the characters of the film to the city and its culture.
by Keith V. McCluskey.
M.Arch.
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Israr, Tauseef A. "A lightweight technique for extracting software architecture and performance models from traces." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ61321.pdf.
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Scheck, Jochen. "Characterisation of lightweight stairs as structure-borne sound sources." Thesis, University of Liverpool, 2011. http://livrepository.liverpool.ac.uk/3653/.
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The work reported in this thesis addresses the problem of structure-borne sound transmission from impacts on lightweight stairs. The primary aim was to provide a laboratory method for characterisation of lightweight stairs as structure-borne sound sources, which will give input data for prediction of the sound transmission in heavyweight building situations. By treating the stair system, combined with impact source(s), as an active component, available methods for active sources could be adapted. The component powers of a timber staircase attached to a solid wall in a staircase test facility have been determined in-situ by use of a reciprocal method. It was shown that the force perpendicular to the wall surface is dominant, moments can be neglected. The force induced power can be predicted from contact free velocity and mobility or by the blocked force as stairs constitute high mobility sources in heavyweight buildings. A practical characterisation is proposed that is based on the reception plate method. It is demonstrated that real walls and floors can be used as reception plates along with a power calibration that circumvents problems in estimating the plate mass, mean squared velocity and total loss factor for non-isolated reception plates. The sound transmission is predicted using EN 12354 and it is confirmed that the prediction gives values within acceptable engineering accuracy. A deterministic model that accounts for the modal coupling of structure and room is used to predict the sound transmission at low frequencies. For the case considered, a major difficulty was found in the modelling of the wall vibration field, mainly due to the boundary conditions that do not correspond to idealised conditions, such as pinned or free edges.
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Niles, Savannah. "Glyph : lightweight and evocative looping images in the news." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98624.
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Thesis: S.M., Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references.
There is an emotional dimension to the informative function of the news. When we read the news we participate in a collective emotional experience- whether that is grief, celebration, worry, or wonder. News video is a crucial vector for these shared emotional experiences, which can propel civic action. But video comes at a high cost in time and attention, and is thus unsuitable for high volume news and social feeds, and mobile and wearable devices. On these interfaces, there is value in presenting video in a way that's immediately evocative, preserving the richness of video while atomizing it to an excerpt as "glanceable" as a still image. This thesis proposes Glyph, a tool for creating expressive, seamlessly-looping GIFs from video. The tool integrates opensource software for video/image manipulation and loop detection into a simple, web-based authoring interface. Glyph allows a user to automatically detect perfect loops that occur in a video, create the appearance of seamless motion in a non-looping clip, still some regions of movement in a clip to highlight others, or imbue a still frame with subtle dynamism. The part-automated, part-manual editing tool thus allows users to quickly build nonliteral excerpts from video that can immediately crystalize an affective quality or crucial moment, suspending and intensifying its semantic or emotional content through continuous, seamless looping. This thesis additionally explores applications for this class of image, called glyphs.
by Savannah Niles.
S.M.
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Marmasse, Natalia 1962. "Providing lightweight telepresence in mobile communication to enhance collaborative living." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28778.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2004.Includes bibliographical references (p. 117-124).
Two decades of computer-supported cooperative work (CSCW) research has addressed how people work in groups and the role technology plays in the workplace. This body of work has resulted in a myriad of deployed technologies with underlying theories and evaluations. It is our hypothesis that similar technologies, and lessons learned from this domain, can also be employed outside the workplace to help people get on with life. The group in this environment is a special set of people with whom we have day-to-day relationships, people who are willing to share intimate personal information. Therefore we call this computer-supported collaborative living. This thesis describes a personal communicator in the form of a watch, intended to provide a link between family members or intimate friends, providing social awareness and helping them infer what is happening in another space and the remote person's availability for communication. The watch enables the wearers to be always connected via awareness cues, text and voice instant message, or synchronous voice connectivity. Sensors worn with the watch track location (via GPS), acceleration, and speech activity; these are classified and conveyed to the other party, where they appear in iconic form on the watch face, providing a lightweight form of telepresence. When a remote person with whom this information is shared examines it, their face appears on the watch of the person being checked on. A number of design criteria defined for collaborative living systems are illustrated through this device.
by Natalia Marmasse.
Ph.D.
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Descamps, Benoît. "Optimal shaping of lightweight structures." Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209362.
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Designing structures for lightness is an intelligent and responsible way for engineers and architects to conceive structural systems. Lightweight structures are able to bridge wide spans with a least amount of material. However, the quest for lightness remains an utopia without the driving constraints that give sense to contemporary structural design.Previously proposed computational methods for designing lightweight structures focused either on finding an equilibrium shape, or are restricted to fairly small design applications. In this work, we aim to develop a general, robust, and easy-to-use method that can handle many design parameters efficiently. These considerations have led to truss layout optimization, whose goal is to find the best material distribution within a given design domain discretized by a grid of nodal points and connected by tentative bars.
This general approach is well established for topology optimization where structural component sizes and system connectivity are simultaneously optimized. The range of applications covers limit analysis and identification of failure mechanisms in soils and masonries. However, to fully realize the potential of truss layout optimization for the design of lightweight structures, the consideration of geometrical variables is necessary.
The resulting truss geometry and topology optimization problem raises several fundamental and computational challenges. Our strategy to address the problem combines mathematical programming and structural mechanics: the structural properties of the optimal solution are used for devising the novel formulation. To avoid singularities arising in optimal configurations, the present approach disaggregates the equilibrium equations and fully integrates their basic elements within the optimization formulation. The resulting tool incorporates elastic and plastic design, stress and displacements constraints, as well as self-weight and multiple loading.
Besides, the inherent slenderness of lightweight structures requires the study of stability issues. As a remedy, we develop a conceptually simple but efficient method to include local and nodal stability constraints in the formulation. Several numerical examples illustrate the impact of stability considerations on the optimal design.
Finally, the investigation on realistic design problems confirms the practical applicability of the proposed method. It is shown how we can generate a range of optimal designs by varying design settings. In that regard, the computational design method mostly requires the designer a good knowledge of structural design to provide the initial guess.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
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Tinashe, Kurehwaseka. "Lightweight Remote Collaboration System based on WebRTC : Improving Remote Collaboration Flexibility." Thesis, Blekinge Tekniska Högskola, Institutionen för kommunikationssystem, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-12816.
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Context. Introduction of efficient multimedia technologies combined with the spreading of high-speed internet connection all over the world has led to the continuous increase in demand of multimedia services, particularly video and audio. One of the major demands are flexible, interoperable and cost-effective lightweight remote collaboration systems in companies. Web Real Time Communication (WebRTC) is an emerging peer to peer technology that is promising to be the solution to many digital real-time communication challenges. With its fantastic one-to-one communication capabilities, WebRTC supports fast and smooth audio calls, video calls, conferencing, data (media file, document and screen) sharing, gaming and all sorts of messages exchange, all being done straight out of the browser. However, as shown by investigations and interviews supported by Ericsson AB and Semcon AB as party of the MERCO (Mediated Effective Remote Collaboration) international project, many corporate use cases of remote collaboration involve applications beyond the conventional one to one communication. Present videoconferencing systems (telepresence) limits the collaboration flexibility due to their lack of the ability to adapt to system resource usage, hence tend to be too heavy for less powerful devices (laptops, tablets, phones). Moreover, their installation and maintenance costs are too expensive for small companies. Therefore, new flexible, lightweight and less expensive solutions for remote collaboration need to be developed. Objectives. The main objective of this thesis is to identify technical solutions to address the challenges of resource usage flexibility in WebRTC multi-party remote collaboration systems. Despite concurrent developments of both commercial and free solutions that provide multi-party videoconferencing services using WebRTC, present solutions such as the conventional Multipoint Control Unit (MCU), Selective Forwarding Unit (SFU) and Fully Meshed architectures suffers from issues of excessive resource usage and cannot deliver the acceptable quality of experience in different use cases, particularly the mobile environment. The aim of this thesis is to investigate lightweight technical solutions that can be used to improve the system resource usage in WebRTC multiparty conferencing systems. Through understanding the architectural designs, benchmarking the performance of various technologies used in WebRTC and selecting the most suitable techniques a prototype is developed as a proof of concept. Methods. The first part of the thesis is dedicated to comprehensive study of fundamentals, background information and related works on WebRTC. This gives knowledge of technologies, techniques and performance evaluation metrics which help in making appropriate technical decisions during the experimental development of WebRTC solutions. The second part of the thesis is dedicated to experimental investigation in which two WebRTC signaling technologies (XSockets and NodeJs) are evaluated based on call setup time in WebRTC group call. Two lightweight technical solutions for improving resource usage flexibility (Switching video quality based on speech and using emotions and gestures instead of video) are evaluated based on system resources (CPU, memory, disk and network) and user experience. Results. Based on call setup time of WebRTC multi-party calls, the experimental results indicates that XSockets is a better signaling technology than NodeJs. The two proposed lightweight solutions have shown a remarkable improvement based on systems resource usage. A 15% reduction of CPU usage is observed when using speech controlled video quality switching and further 10% reduction is observed when video is replaced by emotions and gestures. Conclusions. Despite the minimal resource usage achieved by using emotions technique, this solution has usability issues as it cannot detect emotions in poor lighting environment. Consequently, the solution of switching video quality based on speech is chosen for further implementation. Though, this technique can be further improved through using machine learning techniques, the current implementation can significantly reduce the amount CPU, memory, disk and network usage to allow up to 6 participants to join a single conference call while maintain acceptable quality of experience.
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Park, Sarah S. "Biomimicry of Feathers for Airport Design." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1493714938210786.
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Öqvist, Rikard. "Variations in sound insulation in lightweight timber constructions." Licentiate thesis, Luleå tekniska universitet, Drift, underhåll och akustik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26446.
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This licentiate thesis deals with the topic of variations and uncertainties in building acoustic parameters for lightweight timber constructions. A higher safety margin to the legal requirements is needed to compensate for acoustical uncertainties, which leads to higher costs. Building costs can be reduced if the variations can be identified and controlled. The project was limited to industrially prefabricated timber frame based volumes and massive timber based plate elements. This thesis is based on the work reported in three papers (A, B and C). In paper A, the variations in impact and airborne sound insulation were assessed and quantified in 30 nominally identical volume built apartments in a four-storey building. Large variations were found and the underlying causes were investigated. A statistically significant difference between floor numbers was found as the highest floor achieved better sound insulation. This difference was assumed to be caused by the higher static load on lower floors affecting the elastic layer used to structurally connect the apartments. In paper B, three room volumes were followed and measured at different stages of completion throughout the construction process. The objective was to test if acoustical deviations in the field can be identified at earlier construction stages. An ISO tapping machine was used to excite the floors and the response was measured at 20 positions. The airborne and impact sound insulation were measured in the finished building. Deviations were found, but these could not be traced to earlier stages of completion. In Paper C, the variations in sound insulation of a cross-laminated timber (CLT) building system was investigated. The construction was based on prefabricated wall and floor plate elements which were mounted at the building site. A number of acoustical uncertainties related to the measurement procedure were also investigated. The measurement uncertainty was small in comparison to the total variations. The degree of prefabrication for the CLT system was lower compared to the volume system, which indicated a greater scope for poor workmanship. All papers indicate a higher sound insulation on the upper floors in a building. It is therefore important to carefully design the elastic layer between floor numbers. The measurement uncertainty has been continuously considered in this thesis. In order to properly identify and quantify variations, the measurement uncertainty should be minimised. Advantages and drawbacks with different measurement methods and directions for future research are discussed in the concluding chapters.Godkänd; 2010; 20101110 (ricokv); LICENTIATSEMINARIUM Ämnesområde: Teknisk akustik/Engineering Acoustics Examinator: Professor Anders Ågren, Luleå tekniska universitet Diskutant: Teknologie doktor Christian Simmons, Simmons akustik & utveckling AB, Göteborg Tid: Torsdag den 16 december 2010 kl 13.00 Plats: F719 Taylor, Luleå tekniska universitet
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Hsiao, Chih-Wen, David Turner, and Keith Ross. "A secure lightweight currency service provider." CSUSB ScholarWorks, 2004. https://scholarworks.lib.csusb.edu/etd-project/2594.
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The main purpose of this project is to build a bank system that offers a friendly and simple interface to let users easily manage their lightweight currencies. The Lightweight Currency Protocol (LCP) was originally proposed to solve the problem of fairness in resource cooperatives. However, there are other possible applications of the protocol, including the control of spam and as a general purpose medium of exchange for low value transactions. This project investigates the implementation issues of the LCP, and also investigates LCP bank services to provide human interface to currency operations.
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莊志量 and Chi-leung Richard Chong. "Vertical extension to the Hong Kong Polytechnic University." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31983261.
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Patil, Sharada Krishna. "Usable, lightweight and secure, architecture and programming interface for integration of Wireless Sensor Network to the Cloud." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313592328.
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Karagiannakis, Vasileios. "Application of architectural patterns and lightweight formal method for the validation and verification of safety critical systems." Thesis, Monterey, California: Naval Postgraduate School, 2013. http://hdl.handle.net/10945/37646.
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Approved for public release; distribution is unlimitedThis thesis researches the role of software architectural patterns and lightweight formal methods in safety-critical software development. We present a framework that relates the different activities and products from system engineering, safety engineering, system and software requirements, and software architecture explicitly, and demonstrate the proposed framework with a case study involving the architectural design of the software to control the arming device of a fictitious Surface-to-Air Missile. We describe the safety engineering steps for the identification of the system hazards and the critical functions that the software has to provide to avoid premature detonation, resulting in four safety requirements for the software that controls the missiles Electronic Safe Arm Device (ESAD). We formalize the software safety requirements as statechart assertions and validate their correctness via JUnit test. We develop a software architecture for the control software using the Safety Executive pattern, and implement the design in C++ to support a simple time-step simulation to produce the required log files for the automated verification of the design.
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Mosharrof, Mohammad Sazzad. "Study and modelling of lightweight floor structure regarding its acoustic properties." Licentiate thesis, Luleå tekniska universitet, Drift, underhåll och akustik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17520.
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Lightweight floor structure is widely used in building industries and to have better sound insulation builders come up with different ways of construction. Depending on the construction the floor structure could either be coupled (floor and ceiling coupled by beams) or decoupled (no mechanical connection between floor and ceiling). Although there are many models on coupled structure but for decoupled structure the number is not too many. Keeping that in mind the present thesis talks about lightweight floors: the construction, properties, behaviour etc with a focus on developing a model for decoupled floor structure where the core contribution being the decoupling and adding the moment effect at plate beam joints. The advantage of decoupled structure is that it disconnects the sound bridge through the beams. One consequence on the other hand is that cavity resonance dominates the low frequency region. A comparative analysis is also done with the coupled model. While developing the model this talks about different mathematical tools such as Fourier transform, Floquet principle, Poisson's sum formula etc This also gives an overview of different types of modelling technique available such as analytical, Numerical, energy based approach, empirical method etc. A parametric study is also done here to find out the relative influence of different elements on sound pressure level.Godkänd; 2010; 20100809 (sazmos); LICENTIATSEMINARIUM Ämnesområde: Teknisk akustik/Engineering Acoustics Examinator: Professor Anders Ågren, Luleå tekniska universitet Diskutant: Docent Jonas Brunskog, DTU, Department of Electrical Engineering, Denmark Tid: Tisdag den 7 september 2010 kl 14.00 Plats: F719 Taylor, Luleå tekniska universitet
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Venter, Gert Petrus. "University greenhouse and botanical park : cohesion of a research typology and the metaphysics of space." Diss., Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-02112009-080521.
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Mirhosseiniardakani, Homeiraalsadat, and Homeiraalsadat Mirhosseiniardakani. "Socio-environmental Framework for Integration of Thermal Mass Windcatchers with Lightweight Tensile Structures in Contemporary Hot-Arid Urban Context of Tehran." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/623085.
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The integration of windcatchers in the urban context of hot-arid context of Tehran needs to address two changes in the current utilization: 1) high density context which makes it harder to access to sufficient airflow in the urban context, and 2) sociocultural shifts towards dependencies on modern mechanical air-conditioning systems. Windcatchers are unique tools existing in the hot-arid regions in the Middle East. Windcatcher uses thermal mass, evaporation techniques, and stack effect to deliver human comfort to the residents of the building. Vernacular windcatchers are useful for moderating the indoor air temperature. Yet, using natural ventilation techniques as passive strategies are outdated in recent decades and there are a couple of reasons for that such as maintenance difficulties, lack of urban air filtration methods, decline of cooling efficiency due to modified airflow patterns, habitable space utilization modifications, and dependencies on mechanical cooling systems. On the other hand, tensile structures have the potential to be considered as a tool to upgrade the windcatchers and use them in the modern urban context which will also help reducing energy and reviving local textile industry. This research tries to propose a method that emphasizes on the adaptability of windcatchers and tensile structures, inhabitant control, airflow control and reuse of heavy thermal mass. Also, the proposed model offers improvements for environmental performance of lightweight textiles, such as particulate matter filtration, kinetic energy transformation, and photoresponse for passive shading or natural daylighting strategies. The main goal of this research is to define the parameters required to enhance inhabitant adaptability with the windcatcher and also natural ventilation cooling system. In this research, important characteristics of Sangelaj neighborhood in Tehran are considered such as existing windcatcher dimensions, micro-climate conditions, and urban morphology. Then, different methods are proposed to develop the heat transfer and airflow analysis of the integration between windcatchers and tensile structures. The research suggests methods for adaptation of windcatchers in existing buildings of Tehran using tensile structures. It also proposes methods for the new buildings in the urban context of Sangelaj neighborhood in Tehran.
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Profeta, Daniele. "Mongrel Geometries : Train Station in Torregaveta, a new INFRASTRUCTURAL plaza." Thesis, KTH, Arkitektur, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-34703.
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The thesis project wants to research the concept of Mongrel Geometries, the development of a spatial system that considering the processes of Form Finding as a design tool and their tight relationship with the model of efficiency and structural optimization, start questioning their problem/solving based procedure with the purpose of understanding which are the potentials of these methods to introduce within the built environment new atmospheric and programmatic qualities.The intervention consists in the re-design of the Train Station and of the incorporated Bus Terminal, resolving the general connective tissue, and stimulating the public activity towards the sea side. The Terminal wants to be intended not only as a place of departure but also as an attractive place itself.
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Chong, Chi-leung Richard. "Vertical extension to the Hong Kong Polytechnic University." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B25953886.
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Thesis (M. Arch.)--University of Hong Kong, 1997.Includes special study report entitled: Light-weight structures and construction methodology for vertical extension. Includes bibliographical references.
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Christensen, J. "Topology optimisation of structures exposed to large (non-linear) deformations." Thesis, Coventry University, 2015. http://curve.coventry.ac.uk/open/items/7c0729ce-e19c-414c-9542-c39527d54752/1.
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PhD by portfolio. Research aim: To investigate if topology optimisation can be used for the development of mechanical structures exposed to large (non-linear) deformations. Research objectives: 1. Analyse and critically evaluate the potential for using state of the art commercially available Finite Element software (and associated topology optimisation algorithms) for topology optimisation of structures exposed to large-deformations. 2. Based on 1 (where feasible) suggest, develop and critically appraise opportunities, methodologies and tools for enhancing the accuracy and precision of current state of the art topology optimisation algorithms for non-linear applications. 3. Based on the outcomes of 1 and 2 define / refine and integrate a topology optimisation algorithm / methodology with enhanced levels of accuracy for structures exposed to large (non-linear) deformations. 4. Critically analyse and assess the outcomes of the tool developed in 3 to competing algorithms and “sound engineering judgement” using case-studies and objectively evaluate the potential for further development/refinement of the proposed algorithm/methodology.
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Lucian, Charles. "Geotechnical Aspects of Buildings on Expansive Soils in Kibaha, Tanzania." Doctoral thesis, KTH, Jord- och bergmekanik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9244.
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The focus of this study is on potential damages to buildings resulting from expansive soils in Tanzania, particularly clay soils in Kibaha. For the fact that most of the affected structures are founded on expansive soils, a clear understanding of the behaviour of soils and their interaction with structures has been of interest to the study in order to evaluate properly the source of the problem.The geotechnical behaviour of expansive clay soils is investigated by looking into the geomorphologic, geological and climatic conditions and mineralogical composition of the soils in the study area.Two sites, representative of known problem-areas in Kibaha were selected for geotechnical tests. Geotechnical site investigation consisted of open trial pits, profile description and the collection of both disturbed and undisturbed samples. To extend and amplify the findings, supplementary samples were collected from the environs of the two sites.The collected samples were submitted to soil laboratories at KTH, ARU, SEAMIC and DIT for mineralogical composition tests, natural water content, density, Atterberg limits and swell tests. The results of this investigation indicate that soils in Kibaha contains clay (31%), have high liquid limit (59%) and plastic limit (37%) which indicate high potential swell.Since swell pressure, free swell and swell percent are key properties of expansive soils, the swell properties were measured by free swell tests and one-dimensional oedometer swell tests. The free swell ranged from 100% to 150% and the swell pressure was in the region of 45 kPa. The coefficient of linear extensibility (COLE) was determined for characterizing expansive clays. For all tested samples, COLE ranged from 0.09 to 0.14 indicating that soils fall in the region of high to very high expansion potential rating. The properties of expansive soils were confirmed by the x-ray diffraction test which showed the presence of smectite in the soil. Furthermore, total suction measurement technique using filter paper method indicated that the soils have high suction values, signifying that they have a tendency to swell upon wetting depending on plasticity of particular soil.The depth of the active zone was measured as a function of moisture variations in the profiles during two extreme weather conditions. The active zone depth was found to be between 1.0 and 2.0 m deep. Procedures to assess models to predict swell in the case study were outlined together with their validity.Vertical and horizontal spatial variability in selected soil properties was defined using geostatistical techniques through the fitting of variogram. The indicator semivariograms of both clay contents and free swell gave a range of 20 m horizontally and 1.0 m vertically, with the horizontal variograms exhibiting greater ranges than the dipping variograms.Physical conditions of the surveyed properties in the area confirmed that building damages are associated with poor building materials triggered by expansive soils. In support of the obtained data, the actual behaviour of the foundations was supplemented with prototypes of strip foundations whose performances were monitored over a period of four months. Finally, suggested are the ways forward to solve the problem of foundation on expansive soilQC 20100824
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Dublish, Saumay Kumar. "Managing the memory hierarchy in GPUs." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31205.
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Pervasive use of GPUs across multiple disciplines is a result of continuous adaptation of the GPU architectures to address the needs of upcoming application domains. One such vital improvement is the introduction of the on-chip cache hierarchy, used primarily to filter the high bandwidth demand to the off-chip memory. However, in contrast to traditional CPUs, the cache hierarchy in GPUs is presented with significantly different challenges such as cache thrashing and bandwidth bottlenecks, arising due to small caches and high levels of memory traffic. These challenges lead to severe congestion across the memory hierarchy, resulting in high memory access latencies. In memory-intensive applications, such high memory access latencies often get exposed and can no longer be hidden through multithreading, and therefore adversely impact system performance. In this thesis, we address the inefficiencies across the memory hierarchy in GPUs that lead to such high levels of congestion. We identify three major factors contributing to poor memory system performance: first, disproportionate and insufficient bandwidth resources in the cache hierarchy; second, poor cache management policies; and third, high levels of multithreading. In order to revitalize the memory hierarchy by addressing the above limitations, we propose a three-pronged approach. First, we characterize the bandwidth bottlenecks present across the memory hierarchy in GPUs and identify the architectural parameters that are most critical in alleviating congestion. Subsequently, we explore the architectural design space to mitigate the bandwidth bottlenecks in a cost-effective manner. Second, we identify significant inter-core reuse in GPUs, presenting an opportunity to reuse data among the L1s. We exploit this reuse by connecting the L1 caches with a lightweight ring network to facilitate inter-core communication of shared data. We show that this technique reduces traffic to the L2 cache, freeing up the bandwidth for other accesses. Third, we present Poise, a machine learning approach to mitigate cache thrashing and bandwidth bottlenecks by altering the levels of multi-threading. Poise comprises a supervised learning model that is trained offline on a set of profiled kernels to make good warp scheduling decisions. Subsequently, a hardware inference engine is used to predict good warp scheduling decisions at runtime using the model learned during training. In summary, we address the problem of bandwidth bottlenecks across the memory hierarchy in GPUs by exploring how to best scale, supplement and utilize the existing bandwidth resources. These techniques provide an effective and comprehensive methodology to mitigate the bandwidth bottlenecks in the GPU memory hierarchy.
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Sant'anna, Silvio Stefanini. "Sistemas constritivos leves: e as formas geométricas não euclidianas." Universidade Presbiteriana Mackenzie, 2012. http://tede.mackenzie.br/jspui/handle/tede/474.
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Previous issue date: 2012-12-06This study suggests a discussion of contemporary architecture and its correlation with the lightweight construction systems within a specific approach resulting from materiality and tectonics that have a catalytic role of technological and architectural construction. For architecture, materiality is manifested in its concrete and formal physical expression and contributes to the outcome of the spatiality of the resulting building. The form is a result of the qualification material and performance while matter. Is training conceptive and inventive architect explore the geometry or not shape's geometry. The constructive constraints of the architectural object are reflections of a tectonic able to solve and lead to the technological qualities that limit the performance of building systems must meet. The verification of the segments considered in this study through analysis of works characteristics of these settings will allow verification of the role of technology and development of lightweight construction systems in the settings of contemporary architecture and consequently their relationship to material innovations that these architectures can be realized.
Este estudo propõe a discussão da arquitetura contemporânea e sua correlação com os sistemas construtivos leves dentro de uma abordagem específica, decorrente das novas materialidades e da tectônica, que exercem um papel catalisador das transformações tecnológicas e construtivas arquitetônicas. Para a arquitetura, a materialidade manifestada na sua concretude é expressão física e formal, e contribui para o resultado das espacialidades resultantes do edifício. A forma é resultado da qualificação material e de seu desempenho enquanto matéria. A exploração geométrica ou não geométrica da forma é capacitação conceptiva e inventiva do arquiteto. As condicionantes construtivas do objeto arquitetônico são reflexões de uma tectônica capaz de resolver e levar ao limite as qualidades tecnológicas que o desempenho dos sistemas construtivos deve atender. A verificação dos seguimentos considerados neste estudo por meio de análises de obras características dessas configurações irá permitir a verificação do papel da tecnologia e do desenvolvimento dos sistemas construtivos leves nas configurações da arquitetura contemporânea e, consequentemente, sua relação com as inovações materiais para que essas arquiteturas possam ser realizadas.
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Carassus, Hugo. "Comportement dynamique des matériaux cellulaires issus de la fabrication additive pour l'allègement structural et la sécurité au crash et à l'impact." Electronic Thesis or Diss., Valenciennes, Université Polytechnique Hauts-de-France, 2023. http://www.theses.fr/2023UPHF0003.
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L'essor de la fabrication additive depuis la fin du XXème siècle permet d'envisager la conception de nouveaux matériaux cellulaires architecturés combinant légèreté et grande capacité d'absorption d'énergie. Leur utilisation dans les secteurs du transport terrestre ou aérien revêt alors un intérêt certain pour contribuer conjointement à l'allégement structural et à la sécurité en cas de crash et/ou d'impacts.Les objectifs des travaux de recherche sont d'étudier et de modéliser le comportement mécanique, sous chargements uniaxiaux en dynamique rapide, de cette nouvelle catégorie de matériaux cellulaires, les structures TPMS « Triply Period Minimal Surface », dont l'état de l'art actuel est plutôt centré sur les chargements quasi-statiques ou cycliques.Les travaux présentés dans cette thèse sont organisés en trois volets. La première partie vise à caractériser le comportement mécanique du matériau constitutif, l'acier 316L choisi pour sa grande ductilité, élaboré par le procédé SLM « Selective Laser Melting ». Les spécificités induites par la fusion laser sur lit de poudre telles que l'anisotropie et la sensibilité à la vitesse de déformation sont identifiées et modélisées par des lois de comportement matériaux.La deuxième partie de cette thèse s'intéresse à la réponse mécanique des structures TPMS en régimes quasi-statique et dynamique. Plusieurs paramètres tels que la densité relative ou le type de géométrie sont approfondis. Les réponses mécaniques des structures présentent les caractéristiques d'un absorbeur d'énergie idéal avec l'absence de pic d'entrée, une longue phase plateau légèrement ascendante et une densification tardive. De plus, les mécanismes de déformation sont stables. Comparativement à d'autres matériaux cellulaires dits conventionnels, les capacités d'absorption d'énergie des structures TPMS sont supérieures avec l'avantage d'être moins sensible à la direction de sollicitation pour un chargement uniaxial. En régime dynamique, la hausse observée des capacités d'absorption d'énergie est liée à la sensibilité du matériau constitutif.Cette approche expérimentale est couplée à une approche numérique EF détaillée à l'échelle mésoscopique afin de pouvoir mieux appréhender les mécanismes locaux d'effondrement que la mesure seule ne permet pas, notamment en dynamique. C'est le sujet de la troisième et dernière partie. Le modèle numérique est capable de prédire assez fidèlement la réponse mécanique expérimentale en se basant notamment sur les lois de comportement matériau identifiées au préalable. Localement, la déformation se fait comme une combinaison de plusieurs mécanismes tels que le flambement, la flexion et le cisaillement. Des diagrammes d'absorption d'énergie et des lois de Gibson et Ashby sont déterminés dans l'optique de relier les capacités d'absorption d'énergie aux dimensions géométriques et donc de choisir la configuration la plus adaptée aux spécifications imposéesThe rise of additive manufacturing since the end of the 20th century has made it possible to consider the design of new architectural cellular materials combining lightness and high energy absorption capacity. Their use in the field of ground or air transport sectors is therefore of interest to contribute jointly to structural lightening and safety in the event of a crash and/or impact.The objectives of the research work are to investigate and model the mechanical behaviour, under uniaxial dynamic loadings, of this new category of cellular materials, the TPMS (Triply Period Minimal Surface) structures, for which the current state of the art is rather focused on quasi-static or cyclic loadings.The work presented in this thesis is organised in three parts. The first part aims to characterise the mechanical behaviour of the constitutive material, 316L steel chosen for its high ductility, produced by the SLM (Selective Laser Melting) process. The specificities induced by laser melting on a powder bed, such as anisotropy and strain rate sensitivity, are identified and modelised by material behaviour laws.The second part of this thesis focuses on the mechanical response of TPMS structures under quasi-static and dynamic solicitations. The mechanical responses of the structures show the characteristics of an ideal energy absorber with the absence of an initial peak, a long and slightly rising plateau phase, and a late densification. In addition, the deformation mechanisms are stable. Compared to other so-called conventional cellular materials, the energy absorption capacities of TPMS structures are superior with the advantage of being less sensitive to the direction of solicitation for uniaxial loading. In the dynamic regime, the observed increase in energy absorption capacities is linked to the sensitivity of the constitutive material.This experimental approach is coupled with a detailed numerical FE approach at the mesoscopic scale in order to better understand the local collapse mechanisms that measurement alone does not allow, especially under dynamic solicitations. The numerical model is capable of predicting the experimental mechanical response fairly accurately, based in particular on the material behaviour laws identified previously. Locally, the deformation is a combination of several mechanisms such as buckling, bending and shearing. Energy absorption diagrams and Gibson-Ashby laws are determined in order to relate the energy absorption capacities to the geometrical dimensions and thus to choose the most suitable configuration for the imposed specifications
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Gailliard, Grégory. "Vers une approche commune pour le logiciel et le matériel de spécification et d’implémentation des systèmes embarqués temps-réels distribués, basée sur les intergiciels et les composants orientés objet : Application aux modèles de composants Software Communications Architecture (SCA) et Lightweight Corba Component Model (LwCCM) pour les systèmes de radio logicielle." Cergy-Pontoise, 2010. http://biblioweb.u-cergy.fr/theses/2010CERG0518.pdf.
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Cette thèse s’intéresse à la déclinaison matérielle des concepts logiciels d’intergiciel et d’architecture logicielle à base de composants, conteneurs et connecteurs dans les réseaux de portes programmables in situ (Field-Programmable Gate Array - FPGA). Le domaine d’applications ciblé est la radio définie logiciellement (Software Defined Radio (SDR)) conforme au standard Software Communications Architecture) (SCA). Avec le SCA, les applications radio sont décomposées en composants fonctionnels, qui sont déployés sur des plateformes radios hétérogènes et distribuées. Ces composants fournissent et requièrent des interfaces logicielles abstraites décrites sous forme de signatures d’opérations dans le langage de modélisation unifié appelé Unified Modeling Language (UML) et/ou le langage de définition d’interface (Interface Definition Language - IDL) de l’intergiciel CORBA (Common Object Request Broker Architecture) standardisé par un consortium industriel appelé Object Management Group (OMG). Les besoins de portabilité et de réutilisation de ces composants requièrent que leurs interfaces abstraites définies au niveau système soient indépendantes d’une implémentation logicielle ou matérielle et puissent être indifféremment traduites dans un langage de programmation logiciel tel que C/C++, un langage système tel que SystemC au niveau transaction (Transaction Level Modeling - TLM), ou un langage de description matériel tel que VHDL ou SystemC au niveau registre (Register Transfer Level - (RTL)). Le besoin d’interopérabilité de ces composants requière des communications transparentes quelques soient leur implémentation logicielle ou matérielle et leur distribution. Ces premiers besoins ont été adressés en formalisant des règles de mise en correspondance entre des composants abstraits en OMG IDL3 ou UML2, des composants matériels à base de signaux en VHDL ou SystemC RTL, et des composants systèmes en SystemC TLM. Le deuxième besoin a été adressé en prototypant un intergiciel matériel utilisant de façon transparente le mapping mémoire et deux protocoles messages : CORBA General Inter-Object Request Broker Protocol (GIOP) et SCA Modem Hardware Abstraction Layer (MHAL)This thesis deals with the hardware application of the software concepts of middleware and software architecture based on components, containers and connectors within Field-Programmable Gate Arrays (FPGAs). The target application domain is Software Defined Radio (SDR) compliant with the Software Communications Architecture (SCA). With the SCA, software radio applications are broken into functional waveform components to be deployed on heterogeneous and distributed hardware/software radio platforms. These components provide and require abstract software interfaces described using operation signatures in the Unified Modeling Language (UML) and/or the Interface Definition Language (IDL) of the Common Object Request Broker Architecture (Corba) middleware, both standardized by an international software industry consortium called Object Management Group (OMG). The portability and reusability needs of these business components require that their abstract interfaces defined at a system level are independent of a software or hardware implementation and can be indifferently translated into a software programming language like C/C++, a system language like SystemC at transaction level (Transaction Level Modeling - TLM), or a hardware description language like VHDL or SystemC at Register Transfer Level (RTL). The interoperability need of SDR components requires transparent communications regardless of their hardware/software implementation and their distribution. These first needs were addressed by formalizing mapping rules between abstract components in OMG IDL3 or UML2, signalbased hardware components described in VHDL or SystemC RTL, and system components in SystemC TLM. The second requirement was addressed by prototyping a hardware middleware using transparently memory mapping and two message protocols: Corba General Inter-Object Request Broker Protocol (GIOP) and SCA Modem Hardware Abstraction Layer (MHAL)
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Santos, Bruno Marinho. "Extensões do metamodelo KDM para apoiar modernizações orientadas a aspectos de sistemas legados." Universidade Federal de São Carlos, 2014. https://repositorio.ufscar.br/handle/ufscar/593.
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Previous issue date: 2014-10-21Maintaining legacy systems is a complex and expensive activity for many companies. A recently proposal to solve this problem is Architecture-Driven Modernization (ADM), proposed by Object Management Group (OMG). The ADM consists of a set of concepts and standard metamodels that support systems modernization using models. The Knowledge Discovery Metamodel (KDM) is the main metamodel of ADM, it can represent many artifacts of a legacy system, such as source code, architecture, user interface, configuration files and business process. In general, legacy systems have crosscutting concerns, it can show source code problems like tangling and scattering, and it raises the maintenance costs. The aspect orientation is an alternative to improve crosscutting concerns modularization. Thus, in this dissertation is presented the term Aspect Oriented Modernization that uses the aspect oriented concepts in the ADM context. This modernization process consists in modularize legacy systems with aspects represented in model level. To achieve this goal, in this work were performed a lightweight and a heavyweight extension in the KDM metamodel, to analyze which one would present a better performance if used by Modernization Engineers. The evaluation of these extensions was performed by a case study that considered the modernization with aspects of a small-sized system. To evaluate the case study in both extensions, a set of comparison criteria were created to support the software engineers in choosing the best extension mechanism, according to their needs. In the context of this dissertation an experimental study were developed that aimed reproducing the scenarios that the modernization engineers had to perform maintenances and developing new refactorings in a aspect oriented KDM model. The experiment data considered the development time of the activities and the found number of errors. Finally, it was noticed that the extension mechanism to be choose will depend on the context that it will be applied, however, considering the approach studied here the best extension mechanism is the heavyweight one.
Manter sistemas legados é uma atividade complexa e onerosa para muitas empresas. Uma proposta recente para esse problema é a Modernização Dirigida à Arquitetura (Architecture-Driven Modernization - ADM), proposta pela OMG (Object Management Group). A ADM consiste em um conjunto de princípios e metamodelos padrões que apoiam a modernização de sistemas utilizando modelos. O Knowledge Discovery Metamodel (KDM) é o principal metamodelo da ADM, podendo representar diversos artefatos de um sistema, como código-fonte, arquitetura, interface de usuário, arquivos de configuração e processos de negócio. Em geral, sistemas legados possuem interesses transversais, apresentando problemas de entrelaçamento e espalhamento de código, o que eleva os custos de manutenção. A orientação a aspectos é uma alternativa para melhorar a modularização de interesses transversais. Mediante isso, neste trabalho é apresentado o termo Modernização Orientada a Aspectos que utiliza os conceitos da orientação a aspectos na ADM. Essa modernização consiste em remodularizar sistemas legados utilizando aspectos representados em nível de modelo. Para atingir esse objetivo, foi realizada uma extensão leve e outra pesada do metamodelo KDM, para analisar em qual das duas o desempenho dos engenheiros de modernização seria melhor. Para fazer a avaliação das extensões, foi realizado um estudo de caso levando em consideração a modernização com aspectos em um sistema de pequeno porte. Com o objetivo de avaliar o estudo de caso usando as duas extensões, foram desenvolvidos critérios de comparação que auxiliassem os engenheiros de software a escolher qual dos dois mecanismos de extensão utilizar em seu projeto. Foi feito também um estudo experimental que buscou reproduzir os cenários em que engenheiros de modernização tivessem que realizar manutenções e desenvolver novas refatorações em um modelo KDM orientado a aspectos. Os dados do experimento foram avaliados em relação ao tempo de desenvolvimento das atividades e quantidade de erros encontrados. Por fim, percebeu-se que o mecanismo de extensão a ser utilizado vai depender do contexto em que ele será aplicado, mas, para o domínio aqui estudado a extensão que melhor atendeu aos requisitos foi a pesada.
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Charles, Chadi Robin. "Sustainable solution using biomimicry and architectural lightweight membranes." Master's thesis, 2017. http://hdl.handle.net/1822/56912.
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Dissertação de mestrado em Sustainable Built EnvironmentSustainability is attracting additional importance in daily life through of all the propaganda surrounding global warning issue and how the quality of life on earth is the wickedest that have ever been. The impact of construction and architectural industry contributes in that matter, where solving and arguing that issue is more significant for the building professionals more than ever specially because perhaps time is running out and facing that problem nowadays will result greatly on the future life on earth. In this context, it is possible to say that it is extremely necessary to combine innovative materials and techniques so that alternative solutions can be created in order to make a further step in solving or reducing the negative effect on the planet. This research project intends to study the new technologies and techniques manifested in sustainability where it will tackle the Biomimicry concept and it relation with sustainable questions through the possibility to learn from the environs in order to find a solution. In order to apply the project as a solution to a real situation, this dissertation proposes to design an architectural structure, inspired by the spider’s nets approach, for an exterior space in the centre of the Azurém Campus in the University of Minho, where this space is the hub of pedestrian movements for the university. The architectural structure composed of a grid of bending-active elements, characterizes the decoy for a new and diversified attraction space to the campus. In addition, it is intended to show that the new technologies and materials can be the transitional link between new aspects of the field which interpret a new constructive panorama surrounding the sustainable world.
A questão da sustentabilidade tem assumido uma importância adicional na vida diária da humanidade, através de toda a propaganda em torno do alerta global para a ecologia. O impacto da indústria da construção civil e arquitetônica não foge à regra e contribui em muito para este assunto, dado que os projectos de hoje podem decidir, no futuro, muito da sustentabilidade da vida humana na Terra. Neste contexto, é extremamente necessário combinar materiais e técnicas inovadoras para que possam ser criadas soluções alternativas, a fim de se dar mais um passo em frente na resolução ou redução do efeito negativo no nosso planeta. Este projeto de pesquisa pretende, assim, estudar as novas tecnologias e técnicas de sustentabilidade, abordando o conceito de Biomimética e relacionando questões sustentáveis através da possibilidade de aprender com outras áreas para encontrar uma solução. Para aplicar o projeto como uma solução para uma situação real, esta dissertação propõe a concepção de uma estrutura arquitetônica, inspirado pela abordagem das redes de aranhas, para um espaço exterior no centro do Campus de Azurém, na Universidade do Minho, onde este espaço é o centro de movimentos pedestres para a universidade. A estrutura arquitetônica composta por uma grade de elementos flexíveis, caracteriza o chamariz para um espaço de atração novo e diversificado para o campus. Além disso, pretende mostrar que as novas tecnologias e materiais podem ser o vínculo de transição entre novos aspectos do campo, que interpretam um novo panorama construtivo em torno de um mundo mais sustentável.
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Putera, Christian Antonia Lusiarta, and 安東尼亞. "Incorporating OMA Lightweight M2M Protocol in IoT/M2M Standard Architecture." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/67865369011128888576.
Full textAbstract:
碩士國立交通大學
電機資訊國際學程
103
IoT/M2M aims to integrate a large number of heterogeneous devices which are constantly required to be discovered and reconfigured in order to bring them up to date or to recover their failures. The device management protocol is needed to reduce the amount of time to configure and to manage those IoT/M2M devices, especially for the M2M devices located in the remote area. The device management protocol enables abstraction of an IoT/M2M device as a managed object to ease the management of device; to do this for IoT/M2M devices, this abstraction has to be concise and lightweight. The IoT/M2M international standard organizations, such as ETSI and OneM2M, proposed the use of lightweight device management protocol called Open Mobile Alliance Lightweight M2M (OMA LWM2M) protocol to manage and to configure the IoT/M2M devices from IoT/M2M platform. By incorporating device management in the IoT/M2M platform, we can establish device management sessions that allow an IoT/M2M application to manage IoT/M2M devices remotely from the IoT/M2M service platform. For example, by manipulating resource trees in the cyber space from the IoT/M2M platform we gain access and control to the corresponding sensors/devices in the physical world. However, how to perform resource mapping of OMA LWM2M in the IoT/M2M standard architecture platform is not well addressed by the standard. In this research, we examine how to incorporate the OMA LWM2M in the M2M standard architecture and we analyze how the M2M standard architecture can collaborate and communicate with OMA LWM2M protocol to establish device management sessions. For the experimental process, we analyze the resource mapping of OMA LWM2M objects and resources into the ETSI M2M resource tree by analyzing the processes of (1) Bootstrapping, (2) Registration, and (3) Management and Service Enablement Session. 1. The bootstrapping process is used to provision the OMA LWM2M objects to the IoT/M2M platform for device management session. 2. The registration process is used to register the OMA LWM2M Client and its Objects in the OMA LWM2M Server. This process is analyzed during the device triggering session. 3. The Device Management and Service Enablement Session is a procedure of accessing Object or Resource of the OMA LWM2M Client by an M2M application using OMA LWM2M Server. In order to proceed with our implementation and analysis, we develop Remote Entity Management (REM) Service Capability on top of the OpenMTC, an ETSI M2M standard compliant system from Fraunhofer FOKUS. We also utilize Eclipse Leshan and Wakaama that are the OMA LWM2M open-source reference implementations to implement the REM Capability. To proceed with the analysis, we build an IoT/M2M application and do features testing on it. The feature testing includes the manipulation of the device objects and resources using RESTful commands, the simulation of firmware update mechanism, and the simulation of the remote reboot mechanism for fault management.
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Zaman, Safaa. "A Collaborative Architecture for Distributed Intrusion Detection System based on Lightweight Modules." Thesis, 2009. http://hdl.handle.net/10012/4505.
Full textAbstract:
A variety of intrusion prevention techniques, such as user authentication (e.g.: using passwords), avoidance of programming errors, and information protection, have been used to protect computer systems. However, intrusion prevention alone is not sufficient to protect our systems, as those systems become ever more complex with the rapid growth and expansion of Internet technology and local network systems. Moreover, programming errors, firewall configuration errors, and ambiguous or undefined security policies add to the system’s complexity. An Intrusion Detection System (IDS) is therefore needed as another layer to protect computer systems. The IDS is one of the most important techniques of information dynamic security technology. It is defined as a process of monitoring the events occurring in a computer system or network and analyzing them to differentiate between normal activities of the system and behaviours that can be classified as suspicious or intrusive.
Current Intrusion Detection Systems have several known shortcomings, such as: low accuracy (registering high False Positives and False Negatives); low real-time performance (processing a large amount of traffic in real time); limited scalability (storing a large number of user profiles and attack signatures); an inability to detect new attacks (recognizing new attacks when they are launched for the first time); and weak system-reactive capabilities (efficiency of response). This makes the area of IDS an attractive research field. In recent years, researchers have investigated techniques such as artificial intelligence, autonomous agents, and distributed systems for detecting intrusion in network environments. This thesis presents a novel IDS distributed architecture – Collaborative Distributed Intrusion Detection System (C-dIDS), based on lightweight IDS modules – that integrates two main concepts in order to improve IDS performance and the scalability: lightweight IDS and collaborative architecture.
To accomplish the first concept, lightweight IDS, we apply two different approaches: a features selection approach and an IDS classification scheme. In the first approach, each detector (IDS module) uses smaller amounts of data in the detection process by applying a novel features selection approach called the Fuzzy Enhanced Support Vector Decision Function (Fuzzy ESVDF). This approach improves the system scalability in terms of reducing the number of needed features without degrading the overall system performance. The second approach uses a new IDS classification scheme. The proposed IDS classification scheme employs multiple specialized detectors in each layer of the TCP/IP network model. This helps collecting efficient and useful information for dIDS, increasing the system’s ability to detect different attack types and reducing the system’s scalability.
The second concept uses a novel architecture for dIDS called Collaborative Distributed Intrusion Detection System (C-dIDS) to integrate these different specialized detectors (IDS modules) that are distributed on different points in the network. This architecture is a single-level hierarchy dIDS with a non-central analyzer. To make the detection decision for a specific IDS module in the system, this module must collaborate with the previous IDS module (host) in the lower level of the hierarchy only. Collaborating with other IDS modules improves the overall system accuracy without creating a heavy system overload. Also, this architecture avoids both single point of failure and scalability bottleneck problems.
Integration of the two main concepts, lightweight IDS and a distributed collaborative architecture, has shown very good results and has addressed many IDS limitations.
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Wang, Chao-Hsiung, and 王昭雄. "A security management system based on lightweight wireless access point under AAA architecture." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/42974380688999517364.
Full textAbstract:
碩士國立中興大學
資訊科學研究所
93
Recently, applications of wireless network have grown as a result of the formulation of IEEE 802.11 standard. As the wireless applications are made more available to users, the security issue is becoming more and more challenging. Authentication, Authorization and Accounting (AAA), which was proposed by IETF, provides Wireless Internet Service Providers (WISP) an architecture to authenticate the identity, authorize the permission of wireless communication, and account the access time for each wireless user. By integrating the AAA architecture with the Remote Access Dial-In User Service (RADIUS) protocol, the IEEE 802.1x architecture presents a more secure authentication environment for wireless users. With the IEEE 802.1x architecture, wireless access points play the role of Network Access Server (NAS) and perform the authentication process between wireless users and authentication server. However, not all wireless devices support the IEEE 802.1x or the RADIUS protocol. This paper brings up a concept of Lightweight Wireless Access Point Security Management. Following the AAA architecture, we build a security management system which forwards the processes of authentication, authorization and accounting to the back-end hosts. Wireless Access Points only need to transport messages between wireless users and back-end hosts. Our purpose is to operate authentication, authorization and accounting processes for wireless access point which doesn’t support the RADIUS protocol. As implied by the name, Lightweight Wireless Access Point doesn’t deal with encapsulating or decapsulating any authentication packets but only delivers them to the back-end hosts. Consequently, our AAA architecture could be efficiently operated. The load on wireless access point can be reduced and any further management requirement can be flexibly performed on the back-end host. For example, it is easily expandable for the back-end host to support various EAP authentication methods. Furthermore, the system could be implemented across several network domains and the wireless network manager could effectively control the AAA features of roaming.
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Li, Yu-Shan, and 李羽珊. "A Lightweight Domain-User Architecture Design for Enhancing Signaling Efficiency in IP Multimedia Subsystem." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/34318578365517736269.
Full textAbstract:
碩士國立宜蘭大學
電子工程學系碩士班
101
In the recent years, the Internet and mobile communication technology become popular, and people also have more choice of surfing Internet. The 3rd Generation Partnership Project (3GPP) designed IP Multimedia Subsystem (IMS) for the Next Generation Network (NGN). The new conception called Internet of Things (IoT) is raising, number of mobile devices and mobile users become more and more. In order to deal with the huge traffic and provide more efficient service, the disposition of IMS has to increase. In this thesis, we design a lightweight domain-user architecture to resolve the problem of network usage increasing. This lightweight architecture includes the hierarchical characteristic: use domain concept to manage user for reducing loading component of IMS.
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Chuang, Yun-Ting, and 莊昀庭. "A Lightweight Block Verification Process for Blockchain Architecture: A Case Study of Smart Contract." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/hhzb29.
Full textAbstract:
碩士國立東華大學
資訊管理碩士學位學程
106
The invention of Bitcoin and the booming application of Bitcoin in recent years, push cryptocurrency to its top. Blockchain, the core technology of Bitcoin, has picked up the attention of industry and rapidly adopted by firms. Nowadays, blockchain is adopted by most businesses for increasing their industry value and improving their service quality. Since blockchain has features of decentralization, secure and transparent, the technology mostly applied to financial firms. However, the increasing amount of users creates more blocks, which means the computing burden on clients. This issue can decrease performance and efficiency in firms or organization that adopted the technology or ran the system. Therefore, we proposed a lightweight block verification process in this research. By adopting private chain rather than public chain, the blocks can be reduced. With a private chain applied RSA ring signature and SHA-256 as linking technique, the computing burdens can be reduced and improve the operation efficiency.
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HSU, PEI-EN, and 胥沛恩. "Toward a Lightweight Resource-Oriented Service Architecture for Smart Homes: A Web-of-Things Approach." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/9ntb6b.
Full textAbstract:
碩士逢甲大學
資訊工程學系
104
Recently, smart home system is becoming increasingly important and thus is getting considerable attentions due to the maturing of IoT (Internet of Things) technologies. A lot of IoT applications and devices appear in the consumer market. Various IoT devices collaboratively provide a smart home service, for example, Smart TV, Smart Home security system, and smart light. These devices are interoperated using standard protocols such as SSDP, UPnP, Bluetooth, CoAP, and MQTT. These protocols mediate among the devices and form a smart home services ecosystem. As a result, service discovery and management technology play key roles in a Smart home system. The infrastructure and design of the discovery and management protocol greatly affect the effeciency and resource utilization of the whole system. However, most of existing technologies do not take resource constrained device environment limited bandwidth, computing power and capacity limits into account. In addition, many M2M (Machine to Machine) protocols only support non-IP communication. Hence, developing application among devices spreaded heterogeneous networks is a heavey burden for engineers. For these reasons, this thesis proposes mechanisms that extend CoAP and MQTT protocols for designed smart home services architecture to let the service application and service discovery tierd in this architecture. Also, this paper presents a MQTT-UDP proxy architecture that is able to transparently perform all MQTT core funcionalities. Experimental results show that the proposed architecture and packet overhead traffic is more lightweight, more in line with the communication mode smart home applications, equipment and devices.
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João, Luís Carlos Cavaleiro da Fonseca São. "Estudo da degradação de membranas arquitetónicas." Master's thesis, 2015. http://hdl.handle.net/1822/40445.
Full textAbstract:
Dissertação de mestrado Internacional em Sustentabilidade do Ambiente ConstruídoAs membranas arquitetónicas têm vindo a surgir na sociedade como uma inovação tecnológica e uma filosofia que vai ao encontro dos pressupostos lançados pela sustentabilidade que evidencia a redução de energia e a funcionalidade do sistema, permitindo um maior conforto e utilização por parte das pessoas. As estruturas de membranas são um mundo em constante desenvolvimento, havendo ainda aspetos a melhorar, reforçando e completando assim características por parte do material de construção. A durabilidade das membranas arquitetónicas ao longo do tempo é importante para perceber até que ponto as propriedades mecânicas (resistência à tração) e físicas (conforto higrotérmico) dos materiais são alteradas, promovendo-se a sua degradação. A abordagem de estudo passa por um estudo inicial de duas membranas arquitetónicas: uma em fibra de poliéster com revestimento de PVC (policloreto de vinilo) e a outra membrana em fibra de vidro revestida com PTFE (politetrafluoretileno). Estes materiais são sujeitos a degradação em condições reais de utilização e degradação acelerada por ação da humidade e da radiação ultravioleta, numa câmara climática. O efeito destes agentes na degradação e, consequentemente, na durabilidade das membranas, é avaliado através da perda de resistência e dos níveis de desempenho térmico, dos diferentes materiais, ao longo do tempo. Este trabalho pretende ser um contributo para a compreensão dos fenómenos que levam à deterioração das membranas arquitetónicas e que, muitas vezes, obviam a sua utilização em mais larga escala. A elaboração do estudo da degradação das membranas arquitetónicas demonstra comportamentos lineares de degradação a nível de propriedades térmicas. Na resistência à tração, a membrana de fibra de poliéster/PVC apresenta comportamento linear de tensão ao longo do tempo, mas a membrana de fibra de vidro/PTFE apresenta perda de tensão ao longo do estudo da degradação. Na análise microscópica, ambas as membranas não apresentam indícios de degradação a nível visual, mas a membrana de fibra de poliéster/PVC perde propriedades químicas em relação à sua composição inicial.
The architectural membranes have emerged in society as a technological innovation and a philosophy that meets the assumptions posed by sustainability which shows the reduction of energy and system functionality, allowing greater comfort and use by people. The membrane structures are a world in constant development, with aspects to improve, in order to strength and to complete characteristics from the building material. The durability of architectural membranes over time is an important issue to realize the changes of the mechanical properties (tensile strength) and the physical properties (hygrothermal comfort), that cause the degradation of materials. The study approach involves an initial study of two architectural membranes: the polyester fiber coated with PVC (polyvinyl chloride) and the glass fiber membrane coated with PTFE (polytetrafluoroethylene). These materials are tested to degradation under real conditions of use and accelerated degradation caused by moisture and ultraviolet radiation in a climatic chamber. The effect of these agents in the degradation and, thus the durability of the membranes, is checked by loss of strength and thermal performance levels of the various materials over time. This work is intended as a contribution to the understanding of the phenomena that lead to the deterioration of architectural membranes and often prevents its use on a wider scale. The execution of the study of the degradation of architectural membranes shows linear behavior of the degradation level of thermal properties. The tensile strength, polyester/ PVC fiber membrane show linear behavior over time of tension, but the fiberglass/PTFE membrane shows loss of tension along the degradation study. In microscopic analysis, both membranes show no visual evidence of degradation level, but the polyester/PVC fiber membrane loses chemical properties in relation to its initial composition.
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(6622235), Hyunjun Shin. "Weight Minimization of Sound Packages by Balancing Absorption and Transmission Performance." Thesis, 2019.
Find full textAbstract:
Generally, heavier noise control treatments are favored over lighter ones since heavier acoustical materials tend to insulate (block) noise sources more effectively than do lighter materials. In automotive applications, however, heavier materials cannot always be adopted because of concerns over the total weight of the vehicle. Thus, it would be useful to identify lightweight acoustical treatments that can mitigate vehicle interior noise. Automotive sound packages have both absorption and barrier characteristics, and there is inevitably a trade-off between these two. Therefore, it is important to study the exchange between the absorption and transmission of acoustical materials particularly as it pertains to weight. Here, a procedure based on plane wave analysis is described that can be used to identify weight reduction opportunities by adjusting the acoustical properties of a generic sound package, consisting of a fibrous layer and a flexible microperforated panel surface treatment, so that it meets a target sound pressure level in a downstream interior space. It has been found, for the configuration studied here, that there are lightweight sound package configurations that can maintain acoustical performance equivalent to that of heavier noise treatments, and further, it has been found that the lightest treatments tend to favor barrier performance rather than absorption. Further, the impact of acoustical leaks has been considered, and it has been found that even very small leaks can result in a very substantial weight penalty if a specified level of acoustical performance is to be ensured. Further, the impact of changing the underlying panel mass and altering the frequency weighting used in the optimization process has also been considered.
The optimizer used in the proposed procedure requires considerable calculation time; hence, the acoustic pressure calculation time needs to be minimized to enhance the efficiency of the solution process. Thus, the transfer matrix method (TMM) for a two-dimensional case was used to calculate the interior acoustic pressure for a simple geometry as a starting point in the process of identifying the minimum-weight sound packages. The TMM is a widely used analytical approach to predicting the sound pressure (and particle velocity) for a system that can be represented as a series of subsystems. Although the TMM can offer fast and simple calculations for the acoustic system, its application is limited to a plane-wave-based model. Thus, the TMM is not the best option for the acoustic pressure prediction in a complex geometry such as a vehicle interior, that involves non-planar wave propagation. Therefore, a hybrid TMM-FEA method is proposed in this research to evaluate the acoustical performance of the sound package in more complex geometries (here, a vehicle-like cavity). So, in this research, the TMM was introduced to obtain the initial solutions that can be used in conjunction with the FEA tool to calculate the sound pressure field in the complex geometry case. The correlation between the results of these two approaches was then analyzed to develop a space-averaged pressure prediction model for various absorptive cases in the interior space. Finally, this SAP prediction model was used to generate an acoustic map that can be used to graphically estimate the SAPs in the complex geometry case.
In order to validate the usage of the developed equation for different sets of boundary conditions, several case studies were performed to study the effects of the surface impedance arrangements, geometrical shapes, and, lastly, the presence of extra features in the interior space. Finally, the SAP difference between the area near the driver’s right ear and the total interior cavity was studied to show that the SAP of the total cavity can be adjusted to evaluate the acoustic performance of the sound packages along the lines of conventional industry practice.