Automation of The Guiding Center Expansion (open access)

Automation of The Guiding Center Expansion

We report on the use of the recently-developed Mathematica package VEST (Vector Einstein Summation Tools) to automatically derive the guiding center transformation. Our Mathematica code employs a recursive procedure to derive the transformation order-by-order. This procedure has several novel features. (1) It is designed to allow the user to easily explore the guiding center transformation's numerous nonunique forms or representations. (2) The procedure proceeds entirely in cartesian position and velocity coordinates, thereby producing manifestly gyrogauge invariant results; the commonly-used perpendicular unit vector fields e1, e2 are never even introduced. (3) It is easy to apply in the derivation of higher-order contributions to the guiding center transformation without fear of human error. Our code therefore stands as a useful tool for exploring subtle issues related to the physics of toroidal momentum conservation in tokamaks
Date: March 19, 2013
Creator: Burby, J. W.; Squire, J. & Qin, H.
Object Type: Report
System: The UNT Digital Library
Constraints on Dark Matter Models From a Fermi LAT Search for High-Energy Cosmic-Ray Electrons from the Sun (open access)

Constraints on Dark Matter Models From a Fermi LAT Search for High-Energy Cosmic-Ray Electrons from the Sun

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Date: March 19, 2013
Creator: Ajello, M.; Atwood, W. B.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bellazzini, R. et al.
Object Type: Article
System: The UNT Digital Library
FEMCAM Analysis of SULTAN Test Results for ITER Nb3SN Cable-conduit Conductors (open access)

FEMCAM Analysis of SULTAN Test Results for ITER Nb3SN Cable-conduit Conductors

Performance degradation due to filament fracture of Nb3 Sn cable-in-conduit conductors (CICCs) is a critical issue in large-scale magnet designs such as ITER which is currently being constructed in the South of France. The critical current observed in most SULTAN TF CICC samples is significantly lower than expected and the voltage-current characteristic is seen to have a much broader transition from a single strand to the CICC. Moreover, most conductors exhibit the irreversible degradation due to filament fracture and strain relaxation under electromagnetic cyclic loading. With recent success in monitoring thermal strain distribution and its evolution under the electromagnetic cyclic loading from in situ measurement of critical temperature, we apply FEMCAM which includes strand filament breakage and local current sharing effects to SULTAN tested CICCs to study Nb3 Sn strain sensitivity and irreversible performance degradation. FEMCAM combines the thermal bending effect during cool down and the EM bending effect due to locally accumulating Lorentz force during magnet operation. It also includes strand filament fracture and related local current sharing for the calculation of cable n value. In this paper, we model continuous performance degradation under EM cyclic loading based on strain relaxation and the transition broadening upon cyclic loading to …
Date: March 19, 2013
Creator: Yuhu Zhai, Pierluigi Bruzzone, Ciro Calzolaio
Object Type: Article
System: The UNT Digital Library
Aerodynamic drag reduction of class 8 heavy vehicles: a full-scale wind tunnel study (open access)

Aerodynamic drag reduction of class 8 heavy vehicles: a full-scale wind tunnel study

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Date: March 19, 2013
Creator: Ortega, J.; Salari, K.; Brown, A. & Schoon, R.
Object Type: Report
System: The UNT Digital Library
Is the Transition Redshift a New Cosmological Number? (open access)

Is the Transition Redshift a New Cosmological Number?

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Date: March 19, 2013
Creator: Lima, J. A. S.; Jesus, J. F.; Santos, R. C. & Gill, M. S. S.
Object Type: Article
System: The UNT Digital Library
Wind Generation Feasibility Study for Sac & Fox Tribe of the Mississippi in Iowa (Meskwaki Nation) (open access)

Wind Generation Feasibility Study for Sac & Fox Tribe of the Mississippi in Iowa (Meskwaki Nation)

1.2 Overview The Meskwaki Nation will obtain an anemometer tower. Install the tower at the site that has been pre-qualified as the site most likely to produce maximum electric power from the wind. It will collect meteorological data from the tower’s sensors for a one year period, as required for due diligence to identify the site as appropriate for the installation of a wind turbine to provide electric power for the community. Have the collected data analyzed by a meteorologist and a professionally certified wind engineer to produce the reports of expected power generation at the site, for the specific wind turbine(s) under consideration for installation. 1.2.1 Goals of the Tribe The feasibility study reports, including technical and business analyses will be used to obtain contracts and financing required to develop and implement a wind turbine project on the Meskwaki Settlement. Our goal is to produce two (2) mega watts of power and to reduce the cost for electricity currently being paid by the Meskwaki Casino. 1.2.2 Project Objectives Meet the energy needs of the community with clean energy. Bring renewable energy to the settlement in a responsible, affordable manner. Maximize both the economic and the spiritual benefits to the …
Date: March 19, 2013
Creator: Lasley, Larry C.
Object Type: Report
System: The UNT Digital Library
Confronting Tracker Field Quintessence with Data (open access)

Confronting Tracker Field Quintessence with Data

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Date: March 19, 2013
Creator: Wang, Pao-Yu; /Taiwan, Natl. Taiwan U.; Chen, Chien-Wen; /NCTS, Taipei; Chen, Pisin & /KIPAC, Menlo Park /Taiwan, Natl. Taiwan U.
Object Type: Article
System: The UNT Digital Library
Degradation Of Cementitious Materials Associated With Saltstone Disposal Units (open access)

Degradation Of Cementitious Materials Associated With Saltstone Disposal Units

The Saltstone facilities at the DOE Savannah River Site (SRS) stabilize and dispose of low-level radioactive salt solution originating from liquid waste storage tanks at the site. The Saltstone Production Facility (SPF) receives treated salt solution and mixes the aqueous waste with dry cement, blast furnace slag, and fly ash to form a grout slurry which is mechanically pumped into concrete disposal cells that compose the Saltstone Disposal Facility (SDF). The solidified grout is termed “saltstone”. Cementitious materials play a prominent role in the design and long-term performance of the SDF. The saltstone grout exhibits low permeability and diffusivity, and thus represents a physical barrier to waste release. The waste form is also reducing, which creates a chemical barrier to waste release for certain key radionuclides, notably Tc-99. Similarly, the concrete shell of an SDF disposal unit (SDU) represents an additional physical and chemical barrier to radionuclide release to the environment. Together the waste form and the SDU compose a robust containment structure at the time of facility closure. However, the physical and chemical state of cementitious materials will evolve over time through a variety of phenomena, leading to degraded barrier performance over Performance Assessment (PA) timescales of thousands to …
Date: March 19, 2013
Creator: Flach, G. P. & Smith, F. G., III
Object Type: Report
System: The UNT Digital Library