2,730 research outputs found

    CUSTARD (Cranfield University Space Technology Advanced Research Demonstrator) - A Micro-System Technology Demonstrator Nanosatellite. Summary of the Group Design Project MSc in Astronautics and Space Engineering. 1999-2000, Cranfield University

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    CUSTARD (Cranfield University Space Technology And Research Demonstrator) was the group design project for students of the MSc in Astronautics and Space Engineering for the Academic Year 1999/2000 at Cranfield University. The project involved the initial design of a nanosatellite to be used as a technology demonstrator for microsystem technology (MST) in space. The students worked together as one group (organised into several subgroups, e.g. system, mechanical), with each student responsible for a set of work packages. The nanosatellite designed had a mass of 4 kg, lifetime of 3 months in low Earth orbit, coarse 3-axis attitude control (no orbit control), and was capable of carrying up to 1 kg of payload. The electrical power available was 18 W (peak). Assuming a single X-band ground station at RAL (UK), a data rate of up to 1 M bit s-1 for about 3000 s per day is possible. The payloads proposed are a microgravity laboratory and a formation flying experiment. The report summarises the results of the project and includes executive summaries from all team members. Further information and summaries of the full reports are available from the College of Aeronautics, Cranfield University

    Effectiveness of kanban approaches in systems engineering within rapid response environments

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    AbstractEffective application of systems engineering in rapid response environments has been difficult, particularly those where large, complex brownfield systems or systems of systems exist and are constantly being updated with both short and long term software enhancements. This paper proposes a general case for solving this problem by combining a services approach to systems engineering with a kanban-based scheduling system. It provides the basis for validating the approach with agent-based simulations

    Agile and Lean Systems Engineering: Kanban in Systems Engineering

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    This is the 2nd of two reports that were created for research on this topic funded through SERC. The first report, SERC-TR-032-1 dated March 13, 2012, constituted the 2011-2012 Annual Technical Report and the Final Technical Report of the SERC Research Task RT-6: Software Intensive Systems Data Quality and Estimation Research In Support of Future Defense Cost Analysis. The overall objectives of RT-6 were to use data submitted to DoD in the Software Resources Data Report (SRDR) forms to provide guidance for DoD projects in estimating software costs for future DoD projects. In analyzing the data, the project found variances in productivity data that made such SRDR-based estimates highly variable. The project then performed additional analyses that provided better bases of estimate, but also identified ambiguities in the SRDR data definitions that enabled the project to help the DoD DCARC organization to develop better SRDR data definitions. In SERC-TR-2012-032-1, the resulting Manual provided the guidance elements for software cost estimation performers and users. Several appendices provide further related information on acronyms, sizing, nomograms, work breakdown structures, and references. SERC-TR-2013-032-2 (current report), included the “Software Cost Estimation Metrics Manual.” This constitutes the 2012-2013 Annual Technical Report and the Final Technical Report of the SERC Research Task Order 0024, RT-6: Software Intensive Systems Cost and Schedule Estimation Estimating the cost to develop a software application is different from almost any other manufacturing process. In other manufacturing disciplines, the product is developed once and replicated many times using physical processes. Replication improves physical process productivity (duplicate machines produce more items faster), reduces learning curve effects on people and spreads unit cost over many items. Whereas a software application is a single production item, i.e. every application is unique. The only physical processes are the documentation of ideas, their translation into computer instructions and their validation and verification. Production productivity reduces, not increases, when more people are employed to develop the software application. Savings through replication are only realized in the development processes and on the learning curve effects on the management and technical staff. Unit cost is not reduced by creating the software application over and over again. This manual helps analysts and decision makers develop accurate, easy and quick software cost estimates for different operating environments such as ground, shipboard, air and space. It was developed by the Air Force Cost Analysis Agency (AFCAA) in conjunction with DoD Service Cost Agencies, and assisted by the SERC through involving the University of Southern California and the Naval Postgraduate School. The intent is to improve quality and consistency of estimating methods across cost agencies and program offices through guidance, standardization, and knowledge sharing. The manual consists of chapters on metric definitions, e.g., what is meant by equivalent lines of code, examples of metric definitions from commercially available cost models, the data collection and repository form, guidelines for preparing the data for analysis, analysis results, cost estimating relationships found in the data, productivity benchmarks, future cost estimation challenges and a very large appendix.SERCU.S. Department of DefenseSystems Engineering Research Center (SERC)Systems Engineering Research Center (SERC) Contract H98230-08-D-0171

    Secular values and the location of religion: a spatial analysis of an English medical centre

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    What do contemporary controversies in healthcare reveal about secular values and the location of religion within an English medical centre? Using a socio-spatial methodology designed to break open ideological perspectives and normative values, we analyse the doctor-patient relationship, complementary and alternative medicine, and an issue that bridges the two, evidence-based medicine. In the physical, social and mental spaces of the medical centre we uncover the traces of religious activity and roles and of alternative therapeutic regimes often informed by spiritual or religious systems. Furthermore we disclose the heterogeneity of values that comprise the secular worldview of one group of contemporary general practitioners

    Simultaneous X-ray and Radio Monitoring of the Unusual Binary LSI+61 303: Measurements of the Lightcurve and High-Energy Spectrum

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    The binary system, LSI+61 303, is unusual both because of the dramatic, periodic, radio outbursts, and because of its possible association with the 100 MeV gamma-ray source, 2CG135+01. We have performed simultaneous radio and Rossi X-ray Timing Explorer X-ray observations at eleven intervals over the 26.5 day orbit, and in addition searched for variability on timescales ranging from milliseconds to hours. We confirm the modulation of the X-ray emission on orbital timescales originally reported by Taylor et al. (1996), and in addition we find a significant offset between the peak of the X-ray and radio flux. We argue that based on these results, the most likely X-ray emission mechanism is inverse Compton scattering of stellar photons off of electrons accelerated at the shock boundary between the relativistic wind of a young pulsar and the Be star wind. In these observations we also detected 2 -- 150 keV flux from the nearby low-redshift quasar QSO~0241+622. Comparing these measurements to previous hard X-ray and gamma-ray observations of the region containing both LSI+61 303 and QSO~0241+622, it is clear that emission from the QSO dominates.Comment: 23 pages, 6 figures, Accepted for publication in the Astrophysical Journa
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