92 research outputs found

    Framework for intuitive user interaction with security in the smart home

    Get PDF
    Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 99-104).This thesis presents IntuiSec, a framework for intuitive user interaction with Smart Home security. The design approach of IntuiSec is to introduce a layer of indirection between user-level intent and the system-level security infrastructure. This layer is implemented by a collection of distributed middleware and user-level tools. It encapsulates system-level security events and exposes only concepts and real-world metaphors that are intuitive to non-expert users. It also translates user intent to the appropriate system-level security actions. The IntuiSec framework presents the user with intuitive steps for setting up a secure home network, establishing trusted relationships between devices, and granting temporal, selective access for both home occupants and visitors to devices within the home. The middleware exposes APIs that allow other applications to present the user with meaningful visualizations of security-related parameters and concepts. I present the IntuiSec system design and an example proof-of-concept implementation, which demonstrates the user experience and provides more insight into the framework.by Saad Safer Shakhshir.M.Eng

    NASA/USRA University Advanced Design Program Fourth Annual Summer Conference

    Get PDF
    The study topics cover a broad range of potential space and aeronautics projects which could be undertaken during a 20-30 year period beginning with the Space Station Initial Operating Configuration scheduled for the mid 1990's. Both manned and unmanned endeavors are embraced, and the systems approach to the design problem is emphasized. The student teams pursue the chosen problem during their senior year in a one or two semester capstone design course and submit a comprehensive written report at the conclusion of the project. Finally, student representatives from each of the universities summarize their work in oral presentations at the annual Summer Conference, held at one of the NASA centers and attended by the university faculty, NASA and USRA personnel, and aerospace industry representatives

    RICIS Symposium 1992: Mission and Safety Critical Systems Research and Applications

    Get PDF
    This conference deals with computer systems which control systems whose failure to operate correctly could produce the loss of life and or property, mission and safety critical systems. Topics covered are: the work of standards groups, computer systems design and architecture, software reliability, process control systems, knowledge based expert systems, and computer and telecommunication protocols

    Role of Spin-Dependent Interactions in Chemical Reactions and Molecular Physics

    Get PDF
    This work describes development of theoretical models for applications where spin-dependent interactions play a key role. Specifically, we focus on the spin-orbit and hyperfine interactions in atoms and molecules, which are important for applications in photochemistry, photophysics, materials science, quantum sensing, and quantum computing. In the first part of this work, we discuss development and application of the nonadiabatic statistical theory (NAST) to predict kinetics of spin-forbidden chemical reactions, intersystem crossings and spin-crossovers. We describe the newly developed NAST software package and its capabilities. The package predicts the microcanonical and canonical rate constants for the nonadiabatic spin-orbit coupling driven and traditional adiabatic unimolecular reactions. In addition, the NAST package can calculate the probabilities and rate constants for transitions between individual MS components of the spin multiplets, and process the results of electronic structure calculations to generate the necessary input data for the rate calculations. The second part of this work is motivated by the proposed applications of ultracold atoms in the quantum information science. The ultracold alkali atoms trapped in inert parahydrogen matrix have been shown to possess long coherence times between the hyperfine states |├ F,m_F ⟩─. The long coherence times make these atoms promising candidates for spin-based qubits and quantum sensors. This coherence is limited by interaction between the electron spin of the alkali metal atom and the host matrix. To explain the experimental coherence times of 39K, 85Rb, 87Rb, and 133Cs atoms, we develop a model of inhomogeneous broadening of the transitions between the |├ F,m_F ⟩─ states due to the anisotropic hyperfine interaction between the metal and the host matrix. In the third part of this work, we model the effect of extreme variations in the speed of light on the electronic and atomic structures of small molecules. This part of work is motivated by the theories beyond the Standard Model of physics that treat the fundamental constants as dynamic entities

    Robuste Berechnungsverfahren zur nichtlinearen dynamischen Analyse von Balken- und Schalenstrukturen

    Get PDF
    GegenwĂ€rtige und zukĂŒnftige dynamisch beanspruchte, schlanke Strukturen aus mehrschichtig verbundenen, hyperelastischen Werkstoffen, z. B. Windenergieanlagen und Hubschrauber usw., sind sehr komplex. Eine genaue Untersuchung im Zeitbereich erfordert den Einsatz von Methoden, die kinematische, geometrische sowie, bis zu einem gewissen Grad, materielle NichtlinearitĂ€ten berĂŒcksichtigen sollten. Daher könnten Simulationen mit Beachtung von großen Verschiebungen, Drehungen und Verzerrungen nötig sein, um das mechanische Verhalten akkurat zu vorhersagen zu vermögen. ZunĂ€chst werden die Bewegungsgleichungen rĂ€umlich diskretisiert. Dann werden die zum Teil diskretisierten Gleichungen mittels eines Integrationsverfahrens zeitlich diskretisiert. Solche diskreten Gleichungen sind sehr steif, sodass sich die Berechnung der langzeitigen Lösung erschwert. DarĂŒber hinaus ist die EinfĂŒhrung von Nebenbedingungen oft nötig, um komplexere Strukturen aufstellen zu können, wodurch sich die KomplexitĂ€t erhöht wird und unerwĂŒnschte Eigenschaften noch verschĂ€rft werden. Um Robustheit zu gewinnen, sollen Berechnungsverfahren hergeleitet werden, die die zugrunde legende Physik in gewissem Maße erhalten können und gleichzeitig den hochfrequenten Anteil der Lösung unterdrĂŒcken können. Die ErfĂŒllung dieser Anforderungen stellt sich als sehr herausfordernd dar. Das Hauptziel dieser Arbeit liegt an der Entwicklung von Berechnungsverfahren zur Vertiefung des VerstĂ€ndnises des dynamischen Verhaltens von Balken- und Schalenstrukturen. Um dieses Ziel zu erreichen, wird ein umfassender Ansatz vorgeschlagen. Dieser besteht aus: i) Einer auf Direktoren basierenden, Finite-Elemente-Formulierung fĂŒr den geometrisch exakten Balken mit allgemeinen Querschnittseigenschaften; ii) einer auf Direktoren basierenden, Finite-Elemente-Formulierung fĂŒr die Kontinuumsmechanik-basierte Schale aus mehrschichtig verbundenen, hyperelastischen Werkstoffen; iii) einer vereinheitlichten Beschreibung von Starrkörpern, Balken und Schalen und deren Kopplung mittels kinematischer Nebenbedingungen; und, iv) einem robusten Integrationsverfahren basierend auf dem gemittelten Vektorfeld. Des Weiteren wird Folgendes ebenfalls vorgeschlagen: v) Die Partikularisierung der HauptgeodĂ€tenanalyse zur nichtlinearen Identifikation von Bewegungsmoden an Balkenstrukturen; und, vi) ein neues konservatives/dissipatives Integrationsverfahren fĂŒr allgemeine nichtlineare mechanische Systeme basierend auf optimierten Modifizierungen höherer Ordnung, die die Defizite der Mittelpunktsregel beheben. Die sehr gute Leistung des vorgeschlagenen Ansatzes wird durch mehrere Beispiele unterschiedlicher KomplexitĂ€t nachgewiesen.Existing and new slender structures made of hyperelastic multilayer composite materials subject to highly dynamic loads, e.g., wind turbines, helicopters, cars, speedboats or submarines inter alia, are very complex. Their dynamic analysis requires fully nonlinear formulations, at least from the kinematic and geometric point of view, and also to some extent from the material point of view. Thus, simulations in time-domain involving large displacements, rotations and strains could be necessary to predict their mechanical behavior accurately. Numerical procedures to carry out such simulations rely firstly on the partial discretization in space of the governing equations, for instance with finite elements. These semi discrete equations are further discretized in time with an integration scheme. The resulting discrete equations are in fact very stiff and therefore, the computation of the long-term behavior could be problematic. In many applications, the introduction of constraints is also necessary for rendering more complex structures. Besides introducing a new level of complexity, this can sharpen conditioning problems already present in the fully discrete problem. Additionally, we also require procedures able to annihilate the unwanted unresolved high-frequency content without upsetting of the underlying physics. However, the simultaneous satisfaction of all these requirements is a very challenging task. The main objective of this work is to provide means intended for helping to understand further the nonlinear dynamics of beam and shell structures made of hyperelastic multilayer composite materials subject to highly dynamic loads. To accomplish this main goal, we propose a unifying computational approach that relies on: i) a director-based finite-element formulation for geometrically exact beams with general cross-section properties; ii) a director-based finite-element formulation for solid-degenerate shells made of hyperelastic multilayer composite materials; iii) a unifying description of rigid bodies, geometrically exact beams and solid-degenerate shells and their combination with kinematic pairs, which avoids inherently the necessity of rotational degrees of freedom; and, iv) a robust integration scheme based on the average vector field. Additionally, we propose: v) the particularization of the principal geodesic analysis to identify motion patters exhibited by beam structures in a purely nonlinear setting; and, vi) a new conservative/dissipative integration method for general nonlinear mechanical systems, which relies on high-order correction terms that optimally modify the midpoint rule. Moreover, the excellent numerical performance of the proposed unifying framework and procedures is illustrated by means of a good number of examples with different difficulty levels

    Application of proof plans to computer configuration problems

    Get PDF

    Geometric and scale effects on energy absorption of structural composites

    Get PDF
    PhDThe challenge faced by structural designers is becoming increasingly difficult as the imposed design criteria of energy absorbing structures requires weight reduction of structures without compromising cost and crushing performance. The current research is thus aimed at investigating the energy absorption of fibre reinforced composites measured as a function of geometry and scale within weight-critical structures. At the first stage, an innovative structure composed of four intersecting composite plates was tested. It was found that the structural stability played a crucial role in this intersecting structure. In order to avoid generating buckling failure before turning to a progressive crushing regime, Finite Element Method (FEM) was used on composite structures as a technical tool. At the second stage, three geometric structures containing corrugated composite laminates and possessing better structural stability were designed and examined. To increase the interlaminar fracture toughness properties of composite materials, through-thickness stitching methods were introduced. Fracture toughness (Mode-I and Mode-II) and flexure tests were performed on composite materials for comparing the effectiveness of different crushing mechanisms. Fracture toughness results presented a significant improvement of using stitching methods on Mode-I properties, while slight reduction on Mode-II properties was also detected. They also indicated the flexural properties of structural composites can significantly affect their energy absorption capabilities. At the final stage, six different factors including resin type, fibre architecture, crushing speed and stitching parameters were scaled in several levels in a modified geometric structure. An optimization approach based on Taguchi methods was utilised in order to statistically determine the relationship and assist in evaluating the contribution of each factor on crushing properties. It showed that by selecting the combinations of these factors with correct levels, the energy absorbed can be improved remarkably. It found that the crushing performance of this structural composite was mainly dominated by resin and fibre architecture, which contributed 71% capability of energy absorption. The other 29% capability was dominated by trigger, beam web length, edge stitching density and the crushing speed

    Disruptive Technologies with Applications in Airline & Marine and Defense Industries

    Get PDF
    Disruptive Technologies With Applications in Airline, Marine, Defense Industries is our fifth textbook in a series covering the world of Unmanned Vehicle Systems Applications & Operations On Air, Sea, and Land. The authors have expanded their purview beyond UAS / CUAS / UUV systems that we have written extensively about in our previous four textbooks. Our new title shows our concern for the emergence of Disruptive Technologies and how they apply to the Airline, Marine and Defense industries. Emerging technologies are technologies whose development, practical applications, or both are still largely unrealized, such that they are figuratively emerging into prominence from a background of nonexistence or obscurity. A Disruptive technology is one that displaces an established technology and shakes up the industry or a ground-breaking product that creates a completely new industry.That is what our book is about. The authors think we have found technology trends that will replace the status quo or disrupt the conventional technology paradigms.The authors have collaborated to write some explosive chapters in Book 5:Advances in Automation & Human Machine Interface; Social Media as a Battleground in Information Warfare (IW); Robust cyber-security alterative / replacement for the popular Blockchain Algorithm and a clean solution for Ransomware; Advanced sensor technologies that are used by UUVs for munitions characterization, assessment, and classification and counter hostile use of UUVs against U.S. capital assets in the South China Seas. Challenged the status quo and debunked the climate change fraud with verifiable facts; Explodes our minds with nightmare technologies that if they come to fruition may do more harm than good; Propulsion and Fuels: Disruptive Technologies for Submersible Craft Including UUVs; Challenge the ammunition industry by grassroots use of recycled metals; Changing landscape of UAS regulations and drone privacy; and finally, Detailing Bioterrorism Risks, Biodefense, Biological Threat Agents, and the need for advanced sensors to detect these attacks.https://newprairiepress.org/ebooks/1038/thumbnail.jp

    Nanogenerators in Korea

    Get PDF
    Fossil fuels leaded the 21st century industrial revolution but caused some critical problems such as exhaustion of resources and global warming. Also, current power plants require too much high cost and long time for establishment and facilities to provide electricity. Thus, developing new power production systems with environmental friendliness and low-cost is critical global needs. There are some emerging energy harvesting technologies such as thermoelectric, piezoelectric, and triboelectric nanogenerators, which have great advantages on eco-friendly low-cost materials, simple fabrication, and various operating sources. Since the introduction of various energy harvesting technologies, many novel designs and applications as power suppliers and physical sensors in the world have been demonstrated based on their unique advantages. In this Special Issue, we would like to address and share basic approaches, new designs, and industrial applications related to thermoelectric, piezoelectric, and triboelectric devices which are on-going in Korea. With this Special Issue, we aim to promote fundamental understanding and to find novel ways to achieve industrial product manufacturing for energy harvesters

    Air Force Institute of Technology Research Report 1997

    Get PDF
    This report summarizes the research activities of the Air Force Institute of Technology\u27s Graduate School of Engineering and the Graduate School of Logistics and Acquisition Management. It describes research interests and faculty expertise; list student theses/dissertations; identifies research sponsors and contributions; and outlines the procedure for contacting either school
    • 

    corecore