2,350 research outputs found

    A simulation study of an autonomous steering system for on-road operation of automotive vehicles

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    The study of human driving of automotive vehicles is an important aid to the development of viable autonomous vehicle navigation techniques. Observation of human behavior during driving suggests that this activity involves two distinct levels, the conscious and the unconscious. Conscious actions relate to the logical behavior of a driver such as stopping the vehicle when a traffic light is red, slowing down the vehicle when it turns a bend, etc. Such behavior can be described using natural human language. The unconscious actions of a driver are much less obvious. There are many such activities occurring while we are driving a vehicle to a particular destination. One of the important unconscious efforts involves the selection of successive points on the road to steer the vehicle towards in order to achieve the desired road-following behavior. This research work attempts to mimic this unconscious behavior through the use of a computer simulation model. Keywords: Robotics; Artificial intelligence; Mobile; Mathematical models. (Author)Prepared for: Chief of Naval Researchhttp://archive.org/details/simulationstudyo00mcghsupported by Contract from the United States Army Combat Developments Experimentation Cente

    Pedometry and 'peer support' in older Chinese adults: a 12-month cluster randomised controlled trial

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    Session - Exercise/RehabilitationResearch Dissemination ReportsThere is a need to increase physical activity to attenuate age-related morbidity. This 12-month factorial design cluster trial randomized 399 volunteers from 24 centres to buddy peer support, pedometry, or control group. Data were anaysed using last-observation carried-forward and intention-to-treat methods. Compared to the controls, participants in the pedometry group increased their levels of physical activity energy expenditure significantly, as did those in the buddy group. As recorded by the International Physical Activity Questionnaire [IPAQ], the respective increases amounted to 1820 (95% confidence interval [CI], 1360-2290) and 1260 (95% CI, 780-17 460) metabolic equivalent of task (MET).min.wk-1. The buddy group also had significantly improved aerobic fitness after adjustment for body weight (12%; 95% CI, 4-21%), but this did not attain significance in the pedometry group (7%; 95% CI, -1 to 15%). Our results suggest that recourse to pedometers and the buddy peer support system is simple means of increasing physical activity in older subjects.published_or_final_versio

    Inertial and Magnetic Posture Tracking for Inserting Humans Into Networked Virtual Environments

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    Proceedings of ACM Symposium on Virtual Reality Software & Technology (VRST 2001), Banff, Alberta, Canada, 15 - 17 November 2001, pp.9-16.Accepted/Published Conference Pape

    Three-dimensional visualization of mission planning and control for the NPS autonomous underwater vehicle

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    The article of record may be found at http://dx.doi.org/10.1109/48.107150Oceanic Engineering, IEEE Journal ofThe Naval Postgraduate School (NPS) is constructing a small autonomous underwater vehicle (AUV) with an onboard mission control computer. The mission controller software for this vehicle is a knowledge-based artificial intelligence (AI) system requiring thorough analysis and testing before the AUV is operational. The manner in which rapid prototyping of this software has been demonstrated by developing a controller code on a LISP machine and using an Ethernet link with a graphics workstation to simulate the controller's environment is discussed. The development of a testing simulator using a knowledge engineering environment (KEE) expert system shell that examines AUV controller subsystems and vehicle models before integrating them with the full AUV for its test environment missions is discussed. This AUV simulator utilizes an interactive mission planning control console and is fully autonomous once initial parameters are selecte

    Charged Excitons in Self-assembled Quantum Dots

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    11 páginas, 8 figuras.-- 2002 Mrs Fall Meeting, Boston.-- Victor I. Klimov, Jillian M. Buriak, Wayner Danial D. M., Francesco Priolo, Bruce White (Eds.).We have succeeded in generating highly charged excitons in InAs self-assembled quantum dots by embedding the dots in a field-effect heterostructure. We discover an excitonic Coulomb blockage: over large regions of gate voltage, the exciton charge remains constant. We present here a summary of the emission properties of the charged excitons.This work was funded by EPSRC and the DFG (SFB348).Peer reviewe

    ‘Ethnic group’, the state and the politics of representation

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    The assertion, even if only by implication, that ‘ethnic group’ categories represent ‘real’ tangible entities, indeed identities, is commonplace not only in the realms of political and policy discourse but also amongst contemporary social scientists. This paper, following Brubaker (2002), questions this position in a number of key respects: of these three issues will dominate the discussion that follows. First, there is an interrogation of the proposition that those to whom the categories/labels refer constitute sociologically meaningful ‘groups’ as distinct from (mere) human collectivities. Secondly, there is the question of how these categories emerge, i.e. exactly what series of events, negotiations and contestations lie behind their construction and social acceptance. Thirdly, and as a corollary to the latter point, we explore the process of reification that leads to these categories being seen to represent ‘real things in the world’ (ibid.)

    A Program Evaluation of a Beginning Teacher Support Program in a Small Rural School District in North Carolina

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    As beginning teachers face challenges and seek support, many never receive the guidance needed to help them become effective teachers. Lack of support can build obstacles that lead to job dissatisfaction and failure to retain teachers. Nationwide, states have adopted legislation to require induction programs for new teachers to improve teacher retention and student achievement. This study evaluated the components of a beginning teacher support program in a small rural school district and the perceptions of beginning teacher participants, mentors, and school administrators. In addition, this program evaluation aimed to identifying areas of strength and weaknesses. The analysis of the quantitative and qualitative data collected reveals three main themes: addressing the needs of BTs, lead mentors, and administrators; curriculum and instructional support; and resources to assist BTs with licensure requirements and relevant professional learning opportunities. Based on the analysis of the data collected, recommendations for future research are included. Both the quantitative and qualitative data collected reveal that the beginning teacher support program is practical and beneficial, but there is a need to enhance professional development opportunities for all stakeholders and a need for adequate resources and support throughout a professional development model

    Stable Distributions in Stochastic Fragmentation

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    We investigate a class of stochastic fragmentation processes involving stable and unstable fragments. We solve analytically for the fragment length density and find that a generic algebraic divergence characterizes its small-size tail. Furthermore, the entire range of acceptable values of decay exponent consistent with the length conservation can be realized. We show that the stochastic fragmentation process is non-self-averaging as moments exhibit significant sample-to-sample fluctuations. Additionally, we find that the distributions of the moments and of extremal characteristics possess an infinite set of progressively weaker singularities.Comment: 11 pages, 5 figure

    A Cryogenic Silicon Interferometer for Gravitational-wave Detection

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    The detection of gravitational waves from compact binary mergers by LIGO has opened the era of gravitational wave astronomy, revealing a previously hidden side of the cosmos. To maximize the reach of the existing LIGO observatory facilities, we have designed a new instrument that will have 5 times the range of Advanced LIGO, or greater than 100 times the event rate. Observations with this new instrument will make possible dramatic steps toward understanding the physics of the nearby universe, as well as observing the universe out to cosmological distances by the detection of binary black hole coalescences. This article presents the instrument design and a quantitative analysis of the anticipated noise floor
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