21,661 research outputs found
A Volume Clearing Algorithm for Muon Tomography
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
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
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
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
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 Teachersâ Professional Development Using Community-Based Critical Literacy Practices
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 participantsâ 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
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
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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