27,518 research outputs found

    Arc Jet Testing

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    This course will cover an overview of the Entry Systems and Technology Division (TS) at NASA Ames Research Center (ARC) and descriptions of the extensive arc jet testing complex managed within the branch. After a quick look at the Earth and Planetary Entry projects supported by TS, along with the inventions and software developed within the division, a description of the entry environments to which thermal protection systems (TPS) are exposed will be discussed. The question of "How do we insure TPS survival?" will be answered with descriptions of the various test facilities across the agency and beyond and their applicability. The Ames Arc Jet Complex will then be described, starting with how an arc heater works, adding in the associated infrastructure required to run an arc heater, and the capabilities of each of the test tunnels. Finally, examples of TPS test articles will round out the course

    Updated Analysis of Racial Segregation in Pulaski County Charter and Traditional Public Schools

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    In September of 2009, the Office for Education Policy (OEP) released a report titled “An Analysis of Charter Schools on Desegregation Efforts in Little Rock, Arkansas.” In this report, we presented data from the 2005 to 2009 schools years for students who transferred to open-enrollment charter schools in Pulaski County from the Little Rock School District (LRSD). The aim of this report was to show what impacts – if any – these transfers were having on the desegregation efforts of the LRSD. The motivation for this report was an ongoing legal debate about how charter schools impact desegregation, in which critics of charter schools argued that these schools lead to greater segregation, whereas charter proponents suggested that there was no necessary link between charters and segregation

    Integration in the Little Rock Area, Part 4: What is the Current Level of Integration in Little Rock?

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    School integration has been a contentious policy issue in Little Rock since the 1950s. Recent charter expansions have raised questions about the current level of integration in public schools (charter and traditional) in the Little Rock Area. As part of our series on integration in Little Rock, this brief examines the prevalence of hyper segregated white, black, and economically disadvantaged schools, and calculates the average difference between school demographics and the area’s demographics

    Acoustic Surveys of a Scaled-Model CESTOL Transport Aircraft in Static and Forward Speed Conditions

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    An 11% scale-model of a Cruise-Efficient Short Take-off and Landing (CESTOL) scalemodel test was recently completed. The test was conducted in the AEDC National Full-Scale Aerodynamic Complex (NFAC) 40- by 80-Foot Wind Tunnel at NASA Ames Research Center. The model included two over-wing pod-mounted turbine propulsion simulators (TPS). The hybrid blended wing-body used a circulation control wing (CCW) with leadingand trailing-edge blowing. The bulk of the test matrix included three forward velocities (40 kts, 60 kts, and 100kts), angle-of-attack variation between -5 and 25 , and CCW mass flow variation. Seven strut-mounted microphones outboard of the left wing provided source directivity. A phased microphone array was mounted outboard of the right wing for source location. The goal of this paper is to provide a preliminary look at the acoustic data acquired during the Advanced Model for Extreme Lift and Improved Aeroacoustics (AMELIA) test for 0 angle-of-attack and 0 sideslip conditions. Data presented provides a good overview of the test conditions and the signal-to-noise quality of the data. TPS height variation showed a difference of 2 dB to 3 dB due to wing shielding. Variation of slot mass flow showed increases of 12 dB to 26 dB above the airframe noise and the TPS increased the overall levels an additional 5 dB to 10 dB

    Interspecies Knowledge Transfer for Facial Keypoint Detection

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    We present a method for localizing facial keypoints on animals by transferring knowledge gained from human faces. Instead of directly finetuning a network trained to detect keypoints on human faces to animal faces (which is sub-optimal since human and animal faces can look quite different), we propose to first adapt the animal images to the pre-trained human detection network by correcting for the differences in animal and human face shape. We first find the nearest human neighbors for each animal image using an unsupervised shape matching method. We use these matches to train a thin plate spline warping network to warp each animal face to look more human-like. The warping network is then jointly finetuned with a pre-trained human facial keypoint detection network using an animal dataset. We demonstrate state-of-the-art results on both horse and sheep facial keypoint detection, and significant improvement over simple finetuning, especially when training data is scarce. Additionally, we present a new dataset with 3717 images with horse face and facial keypoint annotations.Comment: CVPR 2017 Camera Read

    Glimmers of a pre-geometric perspective

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    Space-time measurements and gravitational experiments are made by using objects, matter fields or particles and their mutual relationships. As a consequence, any operationally meaningful assertion about space-time is in fact an assertion about the degrees of freedom of the matter (\emph{i.e} non gravitational) fields; those, say for definiteness, of the Standard Model of particle physics. As for any quantum theory, the dynamics of the matter fields can be described in terms of a unitary evolution of a state vector in a Hilbert space. By writing the Hilbert space as a generic tensor product of "subsystems" we analyse the evolution of a state vector on an information theoretical basis and attempt to recover the usual space-time relations from the information exchanges between these subsystems. We consider generic interacting second quantized models with a finite number of fermionic degrees of freedom and characterize on physical grounds the tensor product structure associated with the class of "localized systems" and therefore with "position". We find that in the case of free theories no space-time relation is operationally definable. On the contrary, by applying the same procedure to the simple interacting model of a one-dimensional Heisenberg spin chain we recover the tensor product structure usually associated with "position". Finally, we discuss the possible role of gravity in this framework.Comment: 30 page

    Executive Information Systems Milestone Works: A Preliminary Investigation

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    Since David Nash (1977) first articulated the concept of an “executive information system (EIS)” in 1977, EIS has emerged as an important area in information systems. Similar to the work done studying transaction processing systems (TPS), decision support systems (DSS) and expert systems (ES), the study of EIS has progressed to the point where it is possible to pull back and take a broader look at the field. The purpose of this study is to examine the emergence and development of EIS

    An improved closed loop hybrid phase shift controller for dual active bridge converter

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    In this paper, a new closed loop hybrid phase shift control is proposed for dual active bridge (DAB) converter with variable input voltage. The extended phase shift (EPS) control is applied when load gets heavy enough and the secondary side phase shift angle decreases to zero. When this modified DAB converter operates at light loads, the triple phase shift (TPS) modulation method is applied, and the added control freedom is the secondary phase shift angle between the two-secondary side switching legs. The hybrid phase shift control (HPS) scheme is a combination of EPS and TPS modulations, and it provides a very simple closed form implementation for the primary and secondary side phase shift angles. Depending on the application by changing the phase shift angles we can achieve Buck or Boost operation. A characteristic table feedback control method has been used for closed loop operation. By using 1D look up table the proposed DAB converter provides constant 400V for any given input voltage

    The Cost of Success: The Significance of Funding in the Academic Success of Charter Schools\u27 Minority Students

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    Since the state of Minnesota first began charter schools nearly three decades ago, they have slowly become a major part of public education throughout the United States. Often times strategically placed in communities of low socioeconomic status, charter schools have offered alternative options to at-risk, low-income students who would otherwise attend the traditional public school within their school zones. In New York City today, there are almost four times the number of charter schools than there were ten years ago. Across the city, at-risk students who have the opportunity to attend charter schools are reaching higher levels of educational achievement and succeeding in more varied fields than their public-school-attending counterparts. It is not possible to say that any single factor contributes to the success of charter schools; however, in my investigation I hypothesize that one major contributing factor to New York charter school success is funding. As such, I compared the annual state revenue brought in by charter schools versus that of traditional public schools. In analyzing both total funding for two specific charter networks and six individual public schools, as well as funding per-pupil, I found that funding discrepancies have most likely made a difference in the differing education systems
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