550 research outputs found

    Determining the physical limits on semi‐active control performance: a tutorial

    Full text link
    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106822/1/stc1602.pd

    Average Cross-Sectional Area of DebriSat Fragments Using Volumetrically Constructed 3D Representations

    Get PDF
    Debris fragments from the hypervelocity impact testing of DebriSat are being collected and characterized for use in updating existing satellite breakup models. One of the key parameters utilized in these models is the ballistic coefficient of the fragment which is directly related to its areatomass ratio. However, since the attitude of fragments varies during their orbital lifetime, it is customary to use the average crosssectional area in the calculation of the areatomass ratio. The average crosssectional area is defined as the average of the projected surface areas perpendicular to the direction of motion and has been shown to be equal to onefourth of the total surface area of a convex object. Unfortunately, numerous fragments obtained from the DebriSat experiment show significant concavity (i.e., shadowing) and thus we have explored alternate methods for computing the average crosssectional area of the fragments. An imaging system based on the volumetric reconstruction of a 3D object from multiple 2D photographs of the object was developed for use in determining the size characteristic (i.e., characteristics length) of the DebriSat fragments. For each fragment, the imaging system generates N number of images from varied azimuth and elevation angles and processes them using a spacecarving algorithm to construct a 3D point cloud of the fragment. This paper describes two approaches for calculating the average crosssectional area of debris fragments based on the 3D imager. Approach A utilizes the constructed 3D object to generate equally distributed crosssectional area projections and then averages them to determine the average crosssectional area. Approach B utilizes a weighted average of the area of the 2D photographs to directly compute the average crosssectional area. A comparison of the accuracy and computational needs of each approach is described as well as preliminary results of an analysis to determine the "optimal" number of images needed for the 3D imager to accurately measure the average cross sectional area of objects with known dimensions

    Repositioning of special schools within a specialist, personalised educational marketplace - the need for a representative principle

    Get PDF
    This paper considers how notions of inclusive education as defined in the United Nations Educational, Scientific and Cultural Organization (UNESCO) Salamanca Agreement (1994) have become dissipated, and can be developed and reframed to encourage their progress. It analyses the discourse within a range of academic, legal and media texts, exploring how this dissipation has taken place within the UK. Using data from 78 specialist school websites it contextualises this change in the use of the terms and ideas of inclusion with the rise of two other constructs, the 'specialist school' and 'personalisation'. It identifies the need for a precisely defined representative principle to theorise the type of school which inclusion aims to achieve, which cannot be subsumed by segregated providers. It suggests that this principle should not focus on the individual, but draw upon a liberal/democratic view of social justice, underlining inclusive education's role in removing social barriers that prevent equity, access and participation for all

    Validity of the new lifestyles NL-1000 accelerometer for measuring time spent in moderate-to-vigorous physical activity in school settings

    Get PDF
    Current interest in promoting physical activity in the school environment necessitates an inexpensive, accurate method of measuring physical activity in such settings. Additionally, it is recognized that physical activity must be of at least moderate intensity in order to yield substantial health benefits. The purpose of the study, therefore, was to determine the validity of the New Lifestyles NL-1000 (New Lifestyles, Inc., Lee's Summit, Missouri, USA) accelerometer for measuring moderate-to-vigorous physical activity in school settings, using the Actigraph GT1M (ActiGraph, Pensacola, Florida, USA) as the criterion. Data were collected during a cross-country run (n = 12), physical education (n = 18), and classroom-based physical activities (n = 42). Significant and meaningful intraclass correlations between methods were found, and NL-1000 estimates of moderate-to-vigorous physical activity were not meaningfully different from GT1M-estimated moderate- to-vigorous physical activity. The NL-1000 therefore shows promising validity evidence as an inexpensive, convenient method of measuring moderate-to-vigorous physical activity in school settings

    OPEN XAL Status Report 2015

    Get PDF
    MOPW1050International audienceOpen XAL is an accelerator physics software platformdeveloped in collaboration among several facilitiesaround the world. The Open XAL collaboration wasformed in 2010 to port, improve and extend the successfulXAL platform used at the Spallation Neutron Source foruse in the broader accelerator community and to establishit as the standard platform for accelerator physicssoftware. The site-independent core is complete, activeapplications have been ported, and now we are in theprocess of verification and transitioning to using OpenXAL in production. This paper will present the currentstatus and a roadmap for this project

    Open XAL status Report 2015

    Get PDF
    Open XAL is an accelerator physics software platform developed in collaboration among several facilities around the world. The Open XAL collaboration was formed in 2010 to port, improve and extend the successful XAL platform used at the Spallation Neutron Source for use in the broader accelerator community and to establish it as the standard platform for accelerator physics software. The site-independent core is complete, active applications have been ported, and now we are in the process of verification and transitioning to using Open XAL in production. This paper will present the current status and a roadmap for this project

    Educating a syndrome? Seeking a balance between identifying a learning profile and delivering inclusive education

    Get PDF
    This article summarizes research related to pedagogical approaches to special education, and characteristics of teacher's attitudes and beliefs that supports effective inclusion practices. Additionally, the author summarizes factors that may both enable and disable children with DS's progress, and notes speech and language characteristics from research to date
    corecore