21,661 research outputs found

    A Volume Clearing Algorithm for Muon Tomography

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    The primary objective is to enhance muon-tomographic image reconstruction capability by providing distinctive information in terms of deciding on the properties of regions or voxels within a probed volume "V" during any point of scanning: threat type, non-threat type, or not-sufficient data. An algorithm (MTclear) is being developed to ray-trace muon tracks and count how many straight tracks are passing through a voxel. If a voxel "v" has sufficient number of straight tracks (t), then "v" is a non-threat type voxel, unless there are sufficient number of scattering points (p) in "v" that will make it a threat-type voxel. The algorithm also keeps track of voxels for which not enough information is known: where p and v both fall below their respective threshold parameters. We present preliminary results showing how the algorithm works on data collected with a Muon Tomography station based on gas electron multipliers operated by our group. The MTclear algorithm provides more comprehensive information to a human operator or to a decision algorithm than that provided by conventional muon-tomographic reconstruction algorithms, in terms of qualitatively determining the threat possibility from a probed volume. This is quite important because only low numbers of cosmic ray source muons are typically available in nature for tomography, while a quick determination of threats is essential.Comment: 3 pages, 3 figures, submitted to conf. record of 2014 IEEE Nucl. Sci. Symposium, Seattl

    Resonant tunneling in fractional quantum Hall effect: superperiods and braiding statistics

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    We study theoretically resonant tunneling of composite fermions through their quasi-bound states around a fractional quantum Hall island, and find a rich set of possible transitions of the island state as a function of the magnetic field or the backgate voltage. These considerations have possible relevance to a recent experimental study, and bring out many subtleties involved in deducing fractional braiding statistics.Comment: Phys. Rev. Lett. in pres

    ALTERNATIVE METHODS FOR DISTRIBUTING STATE AID TO LOCAL GOVERNMENTS IN NEW YORK

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    This paper simulates alternative distributions of general purpose state aid to local governments under different combinations of criteria: tax capacity, effort, and revenue needs. Revenue needs are based on Tobit estimates of the costs of providing average levels of 16 categories of services. Segmenting the sample into high and low population jurisdictions provided a more realistic set of cost estimates. Available revenues or capacity are determined by multiplying each jurisdiction's tax bases by standard tax rates. A Need-Capacity gap, the difference between needed revenues and available revenues, is used as a needs-based distribution strategy for general purpose aid. Finally an effort gap, based on above average tax efforts was added to the Need-Capacity gap to define a Need-Capacity-Effort strategy.Public Economics,

    Measurement of the SOC State Specific Heat in ^4He

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    When a heat flux Q is applied downward through a sample of liquid 4He near the lambda transition, the helium self organizes such that the gradient in temperature matches the gravity induced gradient in Tlambda. All the helium in the sample is then at the same reduced temperature tSOC = ((T[sub SOC] - T[sub lambda])/T[sub lambda]) and the helium is said to be in the Self-Organized Critical (SOC) state. We have made preliminary measurements of the 4He SOC state specific heat, C[del]T(T(Q)). Despite having a cell height of 2.54 cm, our results show no difference between C[del]T and the zero-gravity 4He specific heat results of the Lambda Point Experiment (LPE) [J.A. Lipa et al., Phys. Rev. B, 68, 174518 (2003)] over the range 250 to 450 nK below the transition. There is no gravity rounding because the entire sample is at the same reduced temperature tSOC(Q). Closer to Tlambda the SOC specific heat falls slightly below LPE, reaching a maximum at approximately 50 nK below Tlambda, in agreement with theoretical predictions [R. Haussmann, Phys. Rev. B, 60, 12349 (1999)]

    Control System for the LEDA 6.7-MeV Proton Beam Halo Experiment

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    Measurement of high-power proton beam-halo formation is the ongoing scientific experiment for the Low Energy Demonstration Accelerator (LEDA) facility. To attain this measurement goal, a 52-magnet beam line containing several types of beam diagnostic instrumentation is being installed. The Experimental Physics and Industrial Control System (EPICS) and commercial software applications are presently being integrated to provide a real-time, synchronous data acquisition and control system. This system is comprised of magnet control, vacuum control, motor control, data acquisition, and data analysis. Unique requirements led to the development and integration of customized software and hardware. EPICS real-time databases, Interactive Data Language (IDL) programs, LabVIEW Virtual Instruments (VI), and State Notation Language (SNL) sequences are hosted on VXI, PC, and UNIX-based platforms which interact using the EPICS Channel Access (CA) communication protocol. Acquisition and control hardware technology ranges from DSP-based diagnostic instrumentation to the PLC-controlled vacuum system. This paper describes the control system hardware and software design, and implementation.Comment: LINAC2000 Conference, 4 pg

    Reading the World: Supporting Teachers’ Professional Development Using Community-Based Critical Literacy Practices

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    This paper shares the findings from a study that assessed the impact of a graduate level curriculum that engaged fifty-seven k-12 teachers in community-based critical literacy practices. The findings from the participants‘ written critical reflections following two community exploration activities showed that they gained enhanced awareness of social inequalities. In addition, some of the participants made connections between the observed community disparities and their civic responsibilities to work towards social justice

    Curating Automatic Vehicle Location Data to Compare the Performance of Outlier Filtering Methods

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    Agencies use a variety of technologies and data providers to obtain travel time information. The best quality data can be obtained from second-by-second tracking of vehicles, but that data presents many challenges in terms of privacy, storage requirements and analysis. More frequently agencies collect or purchase segment travel time based upon some type of matching of vehicles between two spatially distributed points. Typical methods for that data collection involve license plate re-identification, Bluetooth, Wi-Fi, or some type of rolling DSRC identifier. One of the challenges in each of these sampling techniques is to employ filtering techniques to remove outliers associated with trip chaining, but not remove important features in the data associated with incidents or traffic congestion. This paper describes a curated data set that was developed from high-fidelity GPS trajectory data. The curated data contained 31,621 vehicle observations spanning 42 days; 2,550 observations had travel times greater than 3 minutes more than normal. From this baseline data set, outliers were determined using GPS waypoints to determine if the vehicle left the route. Two performance measures were identified for evaluating three outlier-filtering algorithms by the proportion of true samples rejected and proportion of outliers correctly identified. The effectiveness of the three methods over 10-minute sampling windows was also evaluated. The curated data set has been archived in a digital repository and is available online for others to test outlier-filtering algorithms

    Exact Treatment of the Pauli Exclusion Operator in Nuclear Matter Calculation

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    Exact expressions of the Pauli exclusion operator Q in the nuclear matter calculation are presented in detail. Exact formulae are also given for the calculations of the single-particle-potential energy and the binding energy per nucleon with the exact Q operator. Numerical calculations of the G matrix in the lowest-order Brueckner theory are carried out to check the reliability of the standard angle-average approximation for the Q operator by employing the Bonn B and C NN potentials. It is observed that the exact treatment of the operator Q brings about non-negligible and attractive contributions to the binding energy.Comment: 16 pages, 3 figure
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