7,386 research outputs found

    Feasibility Study of SDAS Instrumentation's Ability to Identify Mobile Launcher (ML)/Crawler-Transporter (CT) Modes During Rollout Operations

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    The Space Launch System (SLS) and its Mobile Launcher (ML) will be transported to the launch pad via the Crawler-Transporter (CT) system. Rollout (i.e., transportation) loads produce structural loads on the integrated SLS/Orion Multi-Purpose Crew Vehicle (MPCV) launch vehicle which are of a concern with respect to fatigue. As part of the risk reduction process and in addition to the modal building block test approach that has been adopted by the SLS Program, acceleration data will be obtained during rollout for use in modal parameter estimation. There are several occurrences where the ML/CT will be transported either into the Vertical Assembly Building (VAB) or to the launch pad and back without the SLS stack as part of the Kennedy Space Center (KSC) Exploration Ground Systems (EGS) Integrated Test and Checkout (ITCO). NASA KSC EGS has instrumentation installed on both the ML and CT to record data during rollout, at the launch pad, and during liftoff. The EGS instrumentation on the ML, which includes accelerometers, is referred to as the Sensor Data Acquisition System (SDAS). The EGS instrumentation on the CT, which also includes accelerometers, is referred to as the CT Data Acquisition System (CTDAS). The forces and accelerations applied to the ML and CT during a rollout event will be higher than any of the planned building block modal tests. This can be very beneficial in helping identify nonlinear behavior in the structure. Developing modal parameters from the same test hardware in multiple boundary conditions and under multiple levels of excitation is a key step in developing a well correlated FEM. The purpose of this study was three fold. First, determine the target modes of the ML/CT in its rollout configuration. Second, determine if the test degrees of freedom (DOF) corresponding to the layout of the SDAS/CTDAS accelerometers (i.e. position and orientation) is sufficient to identify the target modes. Third, determine if the Generic Rollout Forcing Functions (GRFF's) is sufficient for identifying the ML/CT target modes accounting for variations in CT speed, modal damping, and sensor/ambient background noise levels. The finding from the first part of this study identified 28 target modes of the ML/CT rollout configuration based upon Modal Effective Mass Fractions (MEFF) and engineering judgement. The finding from the second part of this study showed that the SDAS/CTDAS accelerometers (i.e. position and orientation) are able to identify a sufficient number of the target modes to support model correlation of the ML/CT FEM. The finding from the third part of this study confirms the GRFFs sufficiently excite the ML/CT such that varying quantities of the defined target modes should be able to be extracted when utilizing an Experimental Modal Analysis (EMA) Multi-Input Multi-Output (MIMO) analysis approach. An EMA analysis approach was used because Operational Modal Analysis (OMA) tools were not available and the GRFFs were sufficiently uncorrelated. Two key findings from this third part of the study are that the CT speed does not show a significant impact on the ability to extract the modal parameters and that keeping the ambient background noise observed at each accelerometer location at or below 30 grms is essential to the success of this approach

    Developing a Professional Standard of Care for Academic Advisors of Student Athletes: Use of Information Based Formative Evaluation in Academic Support

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    Assisting ill prepared student athletes, many of whom are recruited from our nation's inner city schools, in their adjustment to a rigorous college level academic program is a formidable challenge for an academic support program. Building off of Bruno et al. (1987) ,this study attempted to underscore the need for establishing, what might be termed, a ''standard of professional care'' for academic support personnel that is based on the formative evaluation of the student athlete's instructional needs. In this study the use of the information referenced testing (IRT) concept for addressing student athlete information needs was explored and the results of an experiment involving eight N4A institutions were reported. IRT was seen as a cost-effective testing method and its output was an IEP. The test could provide a true picture for what support services students need over the results of a standardized test such as the SAT

    The ongoing contributions of spin-off research and practice to understanding corporate restructuring and wealth creation: $100 billion in 1 decade

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    AbstractSince the 1980s, analysis of spin-offs has become a key line of inquiry in corporate finance. This paper reviews the theory and empirical research papers about spin-off restructuring and measures the monetary value created by spin-offs. First, we document the valuation impact of spin-offs for the divesting firms and then examine such subtleties as the interesting (positive) ex-dividend day price impact and the myriad other details associated with these transactions. This study provides a review of the now extensive research into spin-off divestitures. It looks into equity price reactions around the announcements of 249 voluntary spin-offs undertaken by US public companies over the interval 2007–2017. The abnormal returns associated with recent spin-off divestitures are of the same order of magnitude as those from the earlier papers, showing the sustained statistical significance and new economic materiality measures. With more firms undertaking spin-offs and the positive abnormal returns continuing to be substantial, the clear implication is that the overall monetary value creation resulting from spin-offs has increased markedly. Finally, and in a first for spin-off research, this paper calibrates the monetary value created by spin-offs despite the voluminous research of the topic. It establishes that spin-offs create large monetary value increments for divesting a firm's stockholders—almost $100 billion in the interval 2007–2017

    Going Beyond NCAA Bylaw 5-1-(j): Developing Learning Prescriptions for Student-Athletes

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    In recent years academic support programs for the student-athlete have become an integral component of athletic departments at major colleges and universities. This study reports the use of a test-scoring procedure called Modified Confidence Weighted-Admissible Probability Measurement (MCW-APM) to assist athletic department academic support personnel in diagnosing student-athlete knowledge gaps. A series of nine criterion-­referenced tests (CRT) in fundamental knowledge-base areas of mathematics, language arts, and reading at the elementary, secondary and junior college skill levels was administered to a group of freshmen student­ athletes at UCLA. The MCW-APM test-scoring analysis generated specific learning prescriptions for each student-athlete along with information use­cognitive maps to indicate those knowledge-base areas where the student­-athlete was informed, partially informed, uninformed, or misinformed. The learning prescription was then used by the tutorial program staff for developing an individualized instruction plan. Subsequent clustering of student-athletes by information type was used to design courses, workshops, and special programs with instructional objectives towards reeducation (for misinformed areas), instruction (for areas with lack of information) and review (for areas with partial information)

    Nineteenth-Century Popular Science Magazines, Narrative, and the Problem of Historical Materiality

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    In his Some Reminiscences of a Lecturer, Andrew Wilson emphasizes the importance of narrative to popular science lecturing. Although Wilson promotes the teaching of science as useful knowledge in its own right, he also recognizes that the way science is taught can encourage audiences to take the subject up and read further on their own. Form, according to Wilson, should not be divorced from scientific content and lecturers should ensure that not only is their science accurate, but that it is presented in a way that will provoke curiosity and stimulate interest. This paper discusses the influence of narrative in structuring scientific objects and phenomena, and considers the consequences of such presentations for historical research. As scientific journalism necessarily weaves both its intended audience and the objects under discussion into its accounts, these texts demand that we recognize their nature as social relationships inscribed in historical objects

    The Mass-Concentration Relation and the Stellar-to-Halo Mass Ratio in the CFHT Stripe 82 Survey

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    We present a new measurement of the mass-concentration relation and the stellar-to-halo mass ratio over the halo mass range 5×10125\times 10^{12} to 2×1014M⊙2\times 10^{14}M_{\odot}. To achieve this, we use weak lensing measurements from the CFHT Stripe 82 Survey (CS82), combined with the central galaxies from the redMaPPer cluster catalogue and the LOWZ/CMASS galaxy sample of the Sloan Digital Sky Survey-III Baryon Oscillation Spectroscopic Survey Tenth Data Release. The stacked lensing signals around these samples are modelled as a sum of contributions from the central galaxy, its dark matter halo, and the neighboring halos, as well as a term for possible centering errors. We measure the mass-concentration relation: c200c(M)=A(M200cM0)Bc_{200c}(M)=A(\frac{M_{200c}}{M_0})^{B} with A=5.24±1.24,B=−0.13±0.10A=5.24\pm1.24, B=-0.13\pm0.10 for 0.2<z<0.40.2<z<0.4 and A=6.61±0.75,B=−0.15±0.05A=6.61\pm0.75, B=-0.15\pm0.05 for 0.4<z<0.60.4<z<0.6. These amplitudes and slopes are completely consistent with predictions from recent simulations. We also measure the stellar-to-halo mass ratio for our samples, and find results consistent with previous measurements from lensing and other techniques.Comment: 10 pages, 3 figures, 3 table

    Perforated Sheets as the Porous Material for a Suction-flap Application

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    Two-dimensional tests were made of an NACA 0006 airfoil with area suction applied to a porous region on a 0.3-chord trailing-edge flap deflected 50 degrees. The lift with suction approached the value computed from thin-airfoil theory. The lift gains and suction quantity requirements were unaffected by the perforation patterns of the surface over a wide range of hole sizes and spacings
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