Engineering topics

Jones, Mark

Publications and source records attributed to Jones, Mark.

24 records · Page 2

DOE OSTI2010

Exclusive π∘ and η electro-production at high Q2 in the resonance region

At Jefferson Lab in Hall C, measurements of exclusive $p(e,e^{\prime}p)X$ with $X=\pi^{\circ}$,$\eta$ cross sections were performed for a beam energy of 5.5~GeV. Electrons were detected in the Short Orbit Spectrometer (SOS) at angles of 47.5$^{\circ}$ and 70$^{\circ}$ with a range of invariant mass, W, between meson threshold and 1.8~GeV. The outgoing protons were detected at a range of angles and momentum so that all center of mass angles were covered for most of the W range. The $p(e,e^{\prime}p)\pi^{\circ}$ data was centered at $Q^2 = 6.4 $ and 7.7 GeV$^2$ and the magnetic transition form factor, $G_M^{\star}$, for the $\Delta(1235)$ resonance was extracted from the cross section data. The $p(e,e^{\prime}p)\eta$ data is dominated by the $S_{11}(1535)$ resonance and the helicity conserving transition amplitude, $A_{1/2}$, for the $S_{11}$ was extracted at $Q^2 = 5.7 $ and 7.0 GeV$^2$. These results are at the highest $Q^2$ ever measured and will be discussed in the context of current theoretical models.

Jones, Mark↗

DOE OSTI2010

Polarization Measurements of the Recoil Proton in H(γ⃗ ,p⃗ )π0 reaction*

Perturbative QCD theory predicts that the polarization components of the proton above the baryon resonance region should have a smooth dependence of $E_{\gamma}$, and approach limits established by hadron helicity conservation in the $H(\vec{\gamma},\vec{p})\pi^0$ reaction. Published data shows strong variation of the polarization variables above $2 \mbox{ GeV}$, which could be a sign of high-mass resonances. We present preliminary results for the $\pi^{0}$ photo-production from Jefferson Lab Hall C experiments E04-108, E04-019, E07-002 and Hall A experiment E99-114, which all measured the polarization observables of the recoil proton with high statistics. Our data extends the polarization measurements of $\pi^{0}$ photo-production up to $E_{\gamma}=5.7 \mbox{ GeV}$, with four momentum transfers up to 8.5 GeV$^2$. The results show consistency with published data up to $4.1 \mbox{ GeV}$. We will discuss the interpretation of these results.

Jones, Mark↗

NASA NTRS1995

Parallel adaptive mesh refinement within the PUMAA3D Project

To enable the solution of large-scale applications on distributed memory architectures, we are designing and implementing parallel algorithms for the fundamental tasks of unstructured mesh computation. In this paper, we discuss efficient algorithms developed for two of these tasks: parallel adaptive mesh refinement and mesh partitioning. The algorithms are discussed in the context of two-dimensional finite element solution on triangular meshes, but are suitable for use with a variety of element types and with h- or p-refinement. Results demonstrating the scalability and efficiency of the refinement algorithm and the quality of the mesh partitioning are presented for several test problems on the Intel DELTA.

Freitag, Lori↗

NASA NTRS1988

An improved simulated annealing algorithm for standard cell placement

Simulated annealing is a general purpose Monte Carlo optimization technique that was applied to the problem of placing standard logic cells in a VLSI ship so that the total interconnection wire length is minimized. An improved standard cell placement algorithm that takes advantage of the performance enhancements that appear to come from parallelizing the uniprocessor simulated annealing algorithm is presented. An outline of this algorithm is given.

Jones, Mark↗

NASA NTRS1987

Performance of a parallel algorithm for standard cell placement on the Intel Hypercube

A parallel simulated annealing algorithm for standard cell placement that is targeted to run on the Intel Hypercube is presented. A tree broadcasting strategy that is used extensively in our algorithm for updating cell locations in the parallel environment is presented. Studies on the performance of our algorithm on example industrial circuits show that it is faster and gives better final placement results than the uniprocessor simulated annealing algorithms.

Jones, Mark↗

NASA NTRS1987

Performance of a parallel algorithm for standard cell placement on the Intel Hypercube

A parallel simulated annealing algorithm for standard cell placement on the Intel Hypercube is presented. A novel tree broadcasting strategy is used extensively for updating cell locations in the parallel environment. Studies on the performance of the algorithm on example industrial circuits show that it is faster and gives better final placement results than uniprocessor simulated annealing algorithms.

Jones, Mark↗