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Articles 1 - 30 of 80
Full-Text Articles in Physical Sciences and Mathematics
Semi-Inclusive Charged-Current Neutrino-Nucleus Reactions, O. Moreno, T. W. Donnelly, J. W. Van Orden, W. P. Ford
Semi-Inclusive Charged-Current Neutrino-Nucleus Reactions, O. Moreno, T. W. Donnelly, J. W. Van Orden, W. P. Ford
Physics Faculty Publications
The general, universal formalism for semi-inclusive charged-current (anti) neutrino-nucleus reactions is given for studies of any hadronic system, namely, either nuclei or the nucleon itself. The detailed developments are presented with the former in mind and are further specialized to cases where the final-state charged lepton and an ejected nucleon are presumed to be detected. General kinematics for such processes are summarized, and then explicit expressions are developed for the leptonic and hadronic tensors involved and for the corresponding responses according to the usual charge, longitudinal and transverse projections, keeping finite the masses of all particles involved. In the case …
Repeated Load Relaxation Testing Of Pure Polycrystalline Nickel At Room Temperature Using Nanoindentation, D. E. Stegall, M. A. Mamun, B. Crawford, A, A. Elmustafa
Repeated Load Relaxation Testing Of Pure Polycrystalline Nickel At Room Temperature Using Nanoindentation, D. E. Stegall, M. A. Mamun, B. Crawford, A, A. Elmustafa
Mechanical & Aerospace Engineering Faculty Publications
We present the results of repeated relaxation tests using nanoindentation to derive the activation volume of the dislocation velocity and the ratios of the dislocation density and dislocation velocity. An experimental technique, based on classical uniaxial relaxation experiments, was developed to establish a constant strain during repeated load relaxation transients and then to calculate the stiffness of unloading, and therefore the hardness, across the transients with acceptable results. We found that the activation volume of the dislocation velocity from our nanoindentation methodology was in good agreement when compared to the same reported for uniaxial experiments. © 2014 AIP Publishing LLC.
Enhancing The Insulation Of Wide-Range Spectrum In The Pva/N Thin Film By Doping Zno Nanowires, Yu-Chen Lin, Ching-Hsiang Vhen, Liang-Yih Chen, Shih-Chieh Hsu, Shizhi Qian
Enhancing The Insulation Of Wide-Range Spectrum In The Pva/N Thin Film By Doping Zno Nanowires, Yu-Chen Lin, Ching-Hsiang Vhen, Liang-Yih Chen, Shih-Chieh Hsu, Shizhi Qian
Mechanical & Aerospace Engineering Faculty Publications
In this study, polyvinyl alcohol/nitrogen (PVA/N) hybrid thin films doped with sharp-sword ZnO nanowires with insulating effect and wide-range spectrum are demonstrated for the first time. PVA/N doped ZnO nanocomposites were developed by blending PVA and N-doped ZnO nanowires in water at room temperature. Measurements from the field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Raman, and photoluminescence emission (PL) spectra of the products show that nitrogen is successfully doped into the ZnO wurtzite crystal lattice. In addition, the refractive index of PVA/N doped ZnO hybrid thin films can be controlled by varying the doped ZnO nanowires under different …
Relative Permeability Of Homogenous-Wet And Mixed-Wet Porous Media As Determined By Pore-Scale Lattice Boltzmann Modeling, C. J. Landry, Z. T. Karpyn, O. Ayala
Relative Permeability Of Homogenous-Wet And Mixed-Wet Porous Media As Determined By Pore-Scale Lattice Boltzmann Modeling, C. J. Landry, Z. T. Karpyn, O. Ayala
Engineering Technology Faculty Publications
We present a pore-scale study of two-phase relative permeability in homogenous-wet porous media, and porous media altered to a mixed-wet state. A Shan-Chen type multicomponent lattice Boltzmann (LB) model is employed to determine pore-scale fluid distributions and relative permeability. Mixed-wet states are created by altering the wettability of solid surfaces in contact with the nonwetting phase at the end of steady state simulation of initially homogenous-wet porous media. To ensure accurate representation of fluid-solid interfacial areas, we compare LB simulation results to experimental measurements of interfacial fluid-fluid and fluid-solid areas determined by X-ray computed microtomography imaging of water and oil …
Gpu Accelerated Long-Term Simulations Of Beam-Beam Effects In Colliders, B. Terzić, V. Morozov, Y. Roblin, F. Lin, H. Zhang, M. Aturban, D. Ranjan, M. Zubair
Gpu Accelerated Long-Term Simulations Of Beam-Beam Effects In Colliders, B. Terzić, V. Morozov, Y. Roblin, F. Lin, H. Zhang, M. Aturban, D. Ranjan, M. Zubair
Computer Science Faculty Publications
We present an update on the development of the new code for long-term simulation of beam-beam effects in particle colliders. The underlying physical model relies on a matrix-based arbitrary-order particle tracking (including a symplectic option) for beam transport and the generalized Bassetti-Erskine approximation for beam-beam interaction. The computations are accelerated through a parallel implementation on a hybrid GPU/CPU platform. With the new code, previously computationally prohibitive long-term simulations become tractable. The new code will be used to model the proposed Medium-energy Electron-Ion Collider (MEIC) at Jefferson Lab.
Lattice-Boltzmann Simulations Of The Thermally Driven 2d Square Cavity At High Rayleigh Numbers, Dario Contrino, Pierre Lallemand, Pietro Asinari, Li-Shi Luo
Lattice-Boltzmann Simulations Of The Thermally Driven 2d Square Cavity At High Rayleigh Numbers, Dario Contrino, Pierre Lallemand, Pietro Asinari, Li-Shi Luo
Mathematics & Statistics Faculty Publications
The thermal lattice Boltzmann equation (TLBE) with multiple-relaxation-times (MRT) collision model is used to simulate the steady thermal convective flows in the two-dimensional square cavity with differentially heated vertical walls at high Rayleigh numbers. The MRT-TLBE consists of two sets of distribution functions, i.e., a D2Q9 model for the mass-momentum equations and a D2Q5 model for the temperature equation. The dimensionless flow parameters are the following: the Prandtl number Pr = 0.71 and the Rayleigh number Ra = 106, 107, and 108. The D2Q9 + D2Q5 MRT-TLBE is shown to be second-order accurate and …
Rheological Signatures In Limit Cycle Behaviour Of Dilute, Active, Polar Liquid Crystalline Polymers In Steady Shear, M. Gregory Forest, Panon Phuworawong, Qi Wang, Ruhai Zhou
Rheological Signatures In Limit Cycle Behaviour Of Dilute, Active, Polar Liquid Crystalline Polymers In Steady Shear, M. Gregory Forest, Panon Phuworawong, Qi Wang, Ruhai Zhou
Mathematics & Statistics Faculty Publications
We consider the dilute regime of active suspensions of liquid crystalline polymers (LCPs), addressing issues motivated by our kinetic model and simulations in Forest et al. (Forest et al. 2013 Soft Matter 9, 5207-5222 (doi:10.1039/c3sm27736d)). In particular, we report unsteady two-dimensional heterogeneous flow-orientation attractors for pusher nanorod swimmers at dilute concentrations where passive LCP equilibria are isotropic. These numerical limit cycles are analogous to longwave (homogeneous) tumbling and kayaking limit cycles and two-dimensional heterogeneous unsteady attractors of passive LCPs in weak imposed shear, yet these states arise exclusively at semi-dilute concentrations where stable equilibria are nematic. The results in Forest …
Advances In The Analysis And Prediction Of Turbulent Viscoelastic Flows, T. B. Gatski, L. Thais, G. Mompean
Advances In The Analysis And Prediction Of Turbulent Viscoelastic Flows, T. B. Gatski, L. Thais, G. Mompean
CCPO Publications
It has been well-known for over six decades that the addition of minute amounts of long polymer chains to organic solvents, or water, can lead to significant turbulent drag reduction. This discovery has had many practical applications such as in pipeline fluid transport, oil well operations, vehicle design and submersible vehicle projectiles, and more recently arteriosclerosis treatment. However, it has only been the last twenty-five years that the full utilization of direct numerical simulation of such turbulent viscoelastic flows has been achieved. The unique characteristics of viscoelastic fluid flow are dictated by the nonlinear differential relationship between the flow strain …
Drift Corrected Trends And Periodic Variations In Mipas Imk/Iaa Ozone Measurements, E. Eckert, T. Von Clarmann, M. Kiefer, G. P. Stiller, S. Lossow, N. Glatthor, D. A. Degenstein, L. Froidevaux, S. Godin-Beekmann, T. Leblanc, S. Mcdermid, M. Pastel, W. Steinbrcht, D.P.J. Swart, K. A. Walker, P. F. Bernath
Drift Corrected Trends And Periodic Variations In Mipas Imk/Iaa Ozone Measurements, E. Eckert, T. Von Clarmann, M. Kiefer, G. P. Stiller, S. Lossow, N. Glatthor, D. A. Degenstein, L. Froidevaux, S. Godin-Beekmann, T. Leblanc, S. Mcdermid, M. Pastel, W. Steinbrcht, D.P.J. Swart, K. A. Walker, P. F. Bernath
Chemistry & Biochemistry Faculty Publications
Drifts, trends and periodic variations were calculated from monthly zonally averaged ozone profiles. The ozone profiles were derived from level-1b data of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) by means of the scientific level-2 processor run by the Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research (IMK). All trend and drift analyses were performed using a multilinear parametric trend model which includes a linear term, several harmonics with period lengths from 3 to 24 months and the quasi-biennial oscillation (QBO). Drifts at 2-sigma significance level were mainly negative for ozone relative to Aura MLS and …
Spectrometric Monitoring Of Atmospheric Carbon Tetrafluoride (Cf4) Above The Jungfraujoch Station Since 1989: Evidence Of Continued Increase But At A Slowing Rate, E. Mahieu, R. Zander, G. C. Toon, M. K. Vollmer, S. Reimann, J. Muhle, W. Bader, B. Bovy, B. Lejune, C. Servais, P. F. Bernath
Spectrometric Monitoring Of Atmospheric Carbon Tetrafluoride (Cf4) Above The Jungfraujoch Station Since 1989: Evidence Of Continued Increase But At A Slowing Rate, E. Mahieu, R. Zander, G. C. Toon, M. K. Vollmer, S. Reimann, J. Muhle, W. Bader, B. Bovy, B. Lejune, C. Servais, P. F. Bernath
Chemistry & Biochemistry Faculty Publications
The long-term evolution of the vertical column abundance of carbon tetrafluoride (CF4) above the high-altitude Jungfraujoch station (Swiss Alps, 46.5 ° N, 8.0 ° E, 3580 ma.s.l.) has been derived from the spectrometric analysis of Fourier transform infrared solar spectra recorded at that site between 1989 and 2012. The investigation is based on a multi-microwindow approach, two encompassing pairs of absorption lines belonging to the R-branch of the strong ν3 band of CF4 centered at 1283 cm-1, and two additional ones to optimally account for weak but overlapping HNO3 interferences. The analysis reveals …
Single Spin Asymmetries In Charged Kaon Production From Semi-Inclusive Deep Inelastic Scattering On A Transversely Polarized He-3 Target, Y. X. Zhao, Y. Wang, K. Allada, K. Aniol, J. R. M. Annand, T. Averett, F. Benmokhtar, W. Bertozzi, P. C. Bradshaw, M. Canan
Single Spin Asymmetries In Charged Kaon Production From Semi-Inclusive Deep Inelastic Scattering On A Transversely Polarized He-3 Target, Y. X. Zhao, Y. Wang, K. Allada, K. Aniol, J. R. M. Annand, T. Averett, F. Benmokhtar, W. Bertozzi, P. C. Bradshaw, M. Canan
Physics Faculty Publications
We report the first measurement of target single spin asymmetries of charged kaons produced in semi-inclusive deep inelastic scattering of electrons off a transversely polarized 3He target. Both the Collins and Sivers moments, which are related to the nucleon transversity and Sivers distributions, respectively, are extracted over the kinematic range of0.1 < xbj < 0.4for K+ and K− production. While the Collins and Sivers moments for K+ are consistent with zero within the experimental uncertainties, both moments for K− favor negative values. The Sivers moments are compared to the theoretical prediction from a phenomenological fit to the world data. While …
Data Analysis Techniques, Differential Cross Sections, And Spin Density Matrix Elements For The Reaction 𝛾p → Φp, K. P. Adhikari, D. Adikaram, M. J. Amaryan, C. E. Hyde, S. Koirala, S. E. Kuhn, M. Mayer, I. Niculescu, Et Al., The Clas Collaboration
Data Analysis Techniques, Differential Cross Sections, And Spin Density Matrix Elements For The Reaction 𝛾p → Φp, K. P. Adhikari, D. Adikaram, M. J. Amaryan, C. E. Hyde, S. Koirala, S. E. Kuhn, M. Mayer, I. Niculescu, Et Al., The Clas Collaboration
Physics Faculty Publications
High-statistics measurements of differential cross sections and spin density matrix elements for the reaction γp→ϕp have been made using the CLAS detector at Jefferson Lab. We cover center-of-mass energies (√s) from 1.97 to 2.84 GeV, with an extensive coverage in the ϕ production angle. The high statistics of the data sample made it necessary to carefully account for the interplay between the ϕ natural lineshape and effects of the detector resolution, that are found to be comparable in magnitude. We study both the charged- (ϕ→K+K−) and neutral- (ϕ→K0SK0L) K→ …
Scalar Wave Scattering By Two-Layer Radial Inhomogeneities, Umaporn Nuntaplook, John Adam
Scalar Wave Scattering By Two-Layer Radial Inhomogeneities, Umaporn Nuntaplook, John Adam
Mathematics & Statistics Faculty Publications
It is shown that the iteration technique gives a better approximation for the problem with long wavelengths.
Observation Of D⁰ Meson Nuclear Modifications In Au + Au Collisions At √SNn = 200 Gev, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, C. D. Anson, A. Aparin, D. Arkhipkin, E. C. Aschenauer, G. S. Averichev, A. Banerjee, D. R. Beavis, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, H. Bichsel, M. Zyzak, Et Al., Star Collaboration
Observation Of D⁰ Meson Nuclear Modifications In Au + Au Collisions At √SNn = 200 Gev, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, C. D. Anson, A. Aparin, D. Arkhipkin, E. C. Aschenauer, G. S. Averichev, A. Banerjee, D. R. Beavis, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, H. Bichsel, M. Zyzak, Et Al., Star Collaboration
Physics Faculty Publications
We report the first measurement of charmed-hadron (D0) production via the hadronic decay channel (D0→K−+π+) in Au+Au collisions at √sNN=200 GeV with the STAR experiment. The charm production cross section per nucleon-nucleon collision at midrapidity scales with the number of binary collisions, Nbin, from p+p to central Au+Au collisions. The D0 meson yields in central Au+Au collisions are strongly suppressed compared to those in p+p scaled by Nbin, for transverse momenta pT > 3 GeV/c, demonstrating significant energy loss of charm quarks in the hot …
Progress On The Interaction Region Design And Detector Integration At Jlab's Meic, V. S. Morozov, P. Brindza, A. Camsonne, Ya S. Derbenev, R. Ent, D. Gaskell, F. Lin, P. Nadel-Turonski, M. Ungaro, Y. Zhang, C. E. Hyde, K. Park, M. Sullivan, Z. W. Zhao
Progress On The Interaction Region Design And Detector Integration At Jlab's Meic, V. S. Morozov, P. Brindza, A. Camsonne, Ya S. Derbenev, R. Ent, D. Gaskell, F. Lin, P. Nadel-Turonski, M. Ungaro, Y. Zhang, C. E. Hyde, K. Park, M. Sullivan, Z. W. Zhao
Physics Faculty Publications
One of the unique features of JLab's Medium-energy Electron-Ion Collider (MEIC) is a full-acceptance detector with a dedicated, small-angle, high-resolution detection system, capable of covering a wide range of momenta (and charge-to-mass ratios) with respect to the original ion beam to enable access to new physics. We present an interaction region design developed with close integration of the detection and beam dynamical aspects. The dynamical aspect of the design rests on a symmetry-based concept for compensation of non-linear effects. The optics and geometry have been optimized to accommodate the detection requirements and to ensure the interaction region's modularity for ease …
Neutron Spin Struccture With Polarized Deuterons And Spectator Proton Tagging At Eic, W. Cosyn, V. Guzey, D. W. Higinbotham, C. Hyde, S. Kuhn, P. Nadel-Turonski, K. Park, M. Sargsian, M. Strikman, C. Weiss
Neutron Spin Struccture With Polarized Deuterons And Spectator Proton Tagging At Eic, W. Cosyn, V. Guzey, D. W. Higinbotham, C. Hyde, S. Kuhn, P. Nadel-Turonski, K. Park, M. Sargsian, M. Strikman, C. Weiss
Physics Faculty Publications
The neutron's deep-inelastic structure functions provide essential information for the flavor separation of the nucleon parton densities, the nucleon spin decomposition, and precision studies of QCD phenomena in the flavor-singlet and nonsinglet sectors. Traditional inclusive measurements on nuclear targets are limited by dilution from scattering on protons, Fermi motion and binding effects, final-state interactions, and nuclear shadowing at x ≪ 0.1. An Electron-Ion Collider (EIC) would enable next-generation measurements of neutron structure with polarized deuteron beams and detection of forward-moving spectator protons over a wide range of recoil momenta (0 < pR < several 100MeV in the nucleus rest frame). The free neutron structure functions could be obtained by extrapolating the measured recoil momentum distributions to the on-shell point. The method eliminates nuclear modifications and can be applied to polarized scattering, as well as to semi-inclusive and exclusive final states. We review the prospects for neutron structure measurements with spectator tagging at EIC, the status of R&D efforts, and the accelerator and detector requirements.
Beam-Spin Asymmetries From Semi-Inclusive Pion Electroproduction, K. P. Adhikari, M. J. Amaryan, C. Hyde, S. Koirala, S. E. Kuhn, L. B. Weinstein, Et Al., The Clas Collaboration
Beam-Spin Asymmetries From Semi-Inclusive Pion Electroproduction, K. P. Adhikari, M. J. Amaryan, C. Hyde, S. Koirala, S. E. Kuhn, L. B. Weinstein, Et Al., The Clas Collaboration
Physics Faculty Publications
We have measured the moment Asin ɸLU corresponding to the polarized electron beam-spin asymmetry in semi-inclusive deep inelastic scattering. Asin ɸLU is a twist-3 quantity providing information about quark-gluon correlations. Data were taken with the CLAS Spectrometer at Jefferson Lab using a 5.498 GeV longitudinally polarized electron beam and an unpolarized liquid hydrogen target. All three pion channels (π+,π0 and π-) were measured simultaneously over a large range of kinematics within the virtuality range Q2 ≈ 1.0- 4.5 GeV2. The observable was measured with better than 1% statistical …
Beam Energy Dependence Of Moments Of The Net-Charge Multiplicity Distributions In Au + Au Collisions At Rhic, L. Adamczyk, J. K. Adkins, G. Agakishiev, S. Bültmann, D. Plyku, Star Collaboration
Beam Energy Dependence Of Moments Of The Net-Charge Multiplicity Distributions In Au + Au Collisions At Rhic, L. Adamczyk, J. K. Adkins, G. Agakishiev, S. Bültmann, D. Plyku, Star Collaboration
Physics Faculty Publications
We report the first measurements of the moments-mean (M), variance (σ2), skewness (S), and kurtosis (κ)-of the net-charge multiplicity distributions at midrapidity in Au + Au collisions at seven energies, ranging from √ˢᶰᶰ = 7.7 to 200 GeV, as a part of the Beam Energy Scan program at RHIC. The moments are related to the thermodynamic susceptibilities of net charge, and are sensitive to the location of the QCD critical point. We compare the products of the moments, σ2/M, Sσ, and κσ2, with the expectations from Poisson and negative binomial distributions (NBDs). The Sσ …
Measurement Of Charge Multiplicity Asymmetry Correlations In High-Energy Nucleus-Nucleus Collisions At √ˢᶰᶰ = 200 Gev, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, S. Bültmann, Star Collaboration
Measurement Of Charge Multiplicity Asymmetry Correlations In High-Energy Nucleus-Nucleus Collisions At √ˢᶰᶰ = 200 Gev, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, S. Bültmann, Star Collaboration
Physics Faculty Publications
A study is reported of the same-and opposite-sign charge-dependent azimuthal correlations with respect to the event plane in Au+ Au collisions at √ˢᶰᶰ = 200 GeV. The charge multiplicity asymmetries between the up/down and left/right hemispheres relative to the event plane are utilized. The contributions from statistical fluctuations and detector effects were subtracted from the (co-) variance of the observed charge multiplicity asymmetries. In the mid-to most-central collisions, the same- (opposite-) sign pairs are preferentially emitted in back-to-back (aligned on the same-side) directions. The charge separation across the event plane, measured by the difference, Δ, between the like-and unlike-sign up/down-left/right …
Separated Response Function Ratios In Exclusive, Forward Π± Electroproduction, G. M. Huber, H. P. Blok, C. Butuceanu, D. Gaskell, T. Horn, D. J. Mack, D. Abbott, A. Klein, L. M. Qin, K. Vansyoc
Separated Response Function Ratios In Exclusive, Forward Π± Electroproduction, G. M. Huber, H. P. Blok, C. Butuceanu, D. Gaskell, T. Horn, D. J. Mack, D. Abbott, A. Klein, L. M. Qin, K. Vansyoc
Physics Faculty Publications
The study of exclusive π± electroproduction on the nucleon, including separation of the various structure functions, is of interest for a number of reasons. The ratio R-L=sigma(pi-)(L) / sigma(pi+)(L) is sensitive to isoscalar contamination to the dominant isovector pion exchange amplitude, which is the basis for the determination of the charged pion form factor from electroproduction data. A change in the value of R-T=sigma(pi-)(L) / sigma(pi+)(L) from unity at small -t, to 1/4 at large -t, would suggest a transition from coupling to a (virtual) pion to coupling to individual quarks. Furthermore, the mentioned ratios may show an earlier …
Publisher’S Note: Data Analysis Techniques, Differential Cross Sections, And Spin Density Matrix Elements For The Reaction 𝛾p -> Φp (Phys. Rev. C. Vol 89, 055208, 2014), K. P. Adhikari, D. Adikaram, M. J. Amaryan, C. E. Hyde, A. Klein, S. Koirala, S. E. Kuhn, M. Mayer, I. Niculescu, J. Zhang, Et Al., The Clas Collaboration
Publisher’S Note: Data Analysis Techniques, Differential Cross Sections, And Spin Density Matrix Elements For The Reaction 𝛾p -> Φp (Phys. Rev. C. Vol 89, 055208, 2014), K. P. Adhikari, D. Adikaram, M. J. Amaryan, C. E. Hyde, A. Klein, S. Koirala, S. E. Kuhn, M. Mayer, I. Niculescu, J. Zhang, Et Al., The Clas Collaboration
Physics Faculty Publications
No abstract provided.
Simultaneous Optimization Of The Cavity Heat Load And Trip Rates In Linacs Using A Genetic Algorithm, Balša Terzić, Alicia S. Hofler, Cody J. Reeves, Sabbir A. Khan, Geoffrey A. Krafft, Jay Benesch, Arne Freyberger, Desh Ranjan
Simultaneous Optimization Of The Cavity Heat Load And Trip Rates In Linacs Using A Genetic Algorithm, Balša Terzić, Alicia S. Hofler, Cody J. Reeves, Sabbir A. Khan, Geoffrey A. Krafft, Jay Benesch, Arne Freyberger, Desh Ranjan
Physics Faculty Publications
In this paper, a genetic algorithm-based optimization is used to simultaneously minimize two competing objectives guiding the operation of the Jefferson Lab's Continuous Electron Beam Accelerator Facility linacs: cavity heat load and radio frequency cavity trip rates. The results represent a significant improvement to the standard linac energy management tool and thereby could lead to a more efficient Continuous Electron Beam Accelerator Facility configuration. This study also serves as a proof of principle of how a genetic algorithm can be used for optimizing other linac-based machines.
Length Effects Of A Built-In Flapping Flat Plate On The Flow Over A Traveling Wavy Foil, Nansheng Liu, Yan Peng, Xiyun Lu
Length Effects Of A Built-In Flapping Flat Plate On The Flow Over A Traveling Wavy Foil, Nansheng Liu, Yan Peng, Xiyun Lu
Mathematics & Statistics Faculty Publications
Flow over the traveling wavy foil with a built-in rigid flapping plate at its trailing edge has been numerically studied using the multi-relaxation-time Lattice Boltzmann method and immersed boundary method. The effect of the plate length on the propulsive performance such as the thrust force, energy consumption, and propeller efficiency has been investigated. Three modes (body force dominated, body and tail force competing and tail force dominated modes) have been identified that are associated with different hydrodynamics and flow structures. It is revealed that there exists a better performance plate length region and, within this region, a high propeller efficiency …
Network-Based Assessments Of Percolation-Induced Current Distributions In Sheared Rod Macromolecular Dispersions, Feng Shi, Simi Wang, M. Gregory Forest, Peter J. Mucha, Ruhai Zhou
Network-Based Assessments Of Percolation-Induced Current Distributions In Sheared Rod Macromolecular Dispersions, Feng Shi, Simi Wang, M. Gregory Forest, Peter J. Mucha, Ruhai Zhou
Mathematics & Statistics Faculty Publications
Conducting high-aspect-ratio rods with 1-10 nm-scale diameters dispersed in poorly conducting matrices at extremely low, O(1%), volume fractions induce dramatic gains in bulk conductivity at rod percolation threshold. Experimentally [Nan, Shen, and Ma, Annu. Rev. Mater. Res., 40 (2010), pp. 131-151], bulk conductivity abandons the prepercolation, linear scaling with volume fraction that follows from homogenization theory [Zheng et al., Adv. Funct. Mater., 15 (2005), pp. 627-638], and then postpercolation jumps orders of magnitude to approach that of the pure rod macromolecular phase as predicted by classical percolation theory [Stauffer and Aharony, Introduction to Percolation Theory, CRC …
Precision Measurement Of The Neutron Twist-3 Matrix Element D(2)(N): Probing Color Forces, M. Posik, D. Flay, D. S. Parrno, K. Allada, W. Armstrong, F. Benmokhtar, M. Canan, L. El Fassi, S. Golge, C. Hyde
Precision Measurement Of The Neutron Twist-3 Matrix Element D(2)(N): Probing Color Forces, M. Posik, D. Flay, D. S. Parrno, K. Allada, W. Armstrong, F. Benmokhtar, M. Canan, L. El Fassi, S. Golge, C. Hyde
Physics Faculty Publications
Double-spin asymmetries and absolute cross sections were measured at large Bjorken x (0.25 ≤ x ≤ 0.90), in both the deep-inelastic and resonance regions, by scattering longitudinally polarized electrons at beam energies of 4.7 and 5.9 GeV from a transversely and longitudinally polarized 3He target. In this dedicated experiment, the spin structure function g(2)(3He) was determined with precision at large x, and the neutron twist-3 matrix element d(2)(n) was measured at < Q2> of 3.21 and 4.32 GeV2/c2, with an absolute precision of about 10-5. Our results are found to be in agreement …
Higher Order Mode Damping In Superconducting Spoke Cavities, C. S. Hopper, J. R. Delayen
Higher Order Mode Damping In Superconducting Spoke Cavities, C. S. Hopper, J. R. Delayen
Physics Faculty Publications
Parasitic higher order modes (HOMs) can be severely detrimental to the performance of superconducting cavities. For this reason, the mode spectrum and beam coupling strength must be examined in detail to determine which modes must be damped. One advantage of the spoke cavity geometry is that couplers can be placed on the outer body of the cavity rather than in the beam line space. We present an overview of the HOM properties of spoke cavities and methods for suppressing the most harmful ones.
Cryogenic Test Of A 750 Mhz Superconducting Rf Dipole Crabbing Cavity, A. Castilla, Hyekyoung Park, J. R. Delayen
Cryogenic Test Of A 750 Mhz Superconducting Rf Dipole Crabbing Cavity, A. Castilla, Hyekyoung Park, J. R. Delayen
Physics Faculty Publications
A superconducting rf dipole cavity has been designed to address the challenges of a high repetition rate (750 MHz), high current for both electron/ion species (0.5/3 A per bunch), and large crossing angle (50 mrad) at the interaction points (IPs) crabbing system for the Medium Energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab. The cavity prototype built at Niowave, Inc. has been tested at the Jefferson Lab facilities. In this work we present a detailed analysis of the prototype cavity performance at 4 K and 2 K, corroborating the absence of hard multipacting barriers that could limit the desired transverse …
Cryogenic Testing Of High-Velocity Spoke Cavities, C. S. Hopper, Hyekyoung Park, J. R. Delayen
Cryogenic Testing Of High-Velocity Spoke Cavities, C. S. Hopper, Hyekyoung Park, J. R. Delayen
Physics Faculty Publications
Spoke-loaded cavities are being investigated for the high-velocity regime. The relative compactness at low-frequency makes them attractive for applications requiring, or benefiting from, 4 K operation. Additionally, the large velocity acceptance makes them good candidates for the acceleration of high-velocity protons and ions. Here we present the results of cryogenic testing of a 325 MHz, β0 = 0.82 single-spoke cavity and a 500 MHz, β0 = 1 double-spoke cavity.
Neutral Pion Cross Section And Spin Asymmetries At Intermediate Pseudorapidity In Polarized Proton Collisions At √ S = 200 Gev, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, S. Bültmann, I. Koralt, D. Plyku, Star Collaboration
Neutral Pion Cross Section And Spin Asymmetries At Intermediate Pseudorapidity In Polarized Proton Collisions At √ S = 200 Gev, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, S. Bültmann, I. Koralt, D. Plyku, Star Collaboration
Physics Faculty Publications
The differential cross section and spin asymmetries for neutral pions produced within the intermediate pseudorapidity range 0.8<η/c and is found to agree with a next-to-leading order perturbative QCD calculation. The longitudinal double-spin asymmetry ALL is measured in the same pseudorapidity range and spans a range of Bjorken-x down to x≈0.01. The measured ALL is consistent with model predictions for varying degrees of gluon polarization. The parity-violating asymmetry AL is also measured and found to be consistent with zero. The transverse single-spin asymmetry AN is measured over a previously unexplored kinematic range in Feynman-x and PT. Such measurements may aid our understanding of the onset and kinematic dependence of the large asymmetries observed …
Precision Measurements Of G¹ Of The Proton And The Deuteron With 6 Gev Electrons, Y. Prok, K. P. Adhikari, D. Adikaram, M. J. Amaryan, G. E. Dodge, N. Guler, A. Klein, S. Koirala, S. E. Kuhn, Clas Collaboration
Precision Measurements Of G¹ Of The Proton And The Deuteron With 6 Gev Electrons, Y. Prok, K. P. Adhikari, D. Adikaram, M. J. Amaryan, G. E. Dodge, N. Guler, A. Klein, S. Koirala, S. E. Kuhn, Clas Collaboration
Physics Faculty Publications
The inclusive polarized structure functions of the proton and deuteron, gp1 and gd1 , were measured with high statistical precision using polarized 6 GeV electrons incident on a polarized ammonia target in Hall B at Jefferson Laboratory. Electrons scattered at laboratory angles between 18 and 45 degrees were detected using the CEBAF Large Acceptance Spectrometer (CLAS). For the usual deep inelastic region kinematics, Q2 > 1 GeV2 and the final-state invariant mass W >2 GeV, the ratio of polarized to unpolarized structure functions g1/F1 is found to be nearly independent of Q …