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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
Caching And Writeback Policies In Parallel File Systems, David Kotz, Carla Schlatter Ellis
Caching And Writeback Policies In Parallel File Systems, David Kotz, Carla Schlatter Ellis
Dartmouth Scholarship
Improvements in the processing speed of multiprocessors are outpacing improvements in the speed of disk hardware. Parallel disk I/O subsystems have been proposed as one way to close the gap between processor and disk speeds. Such parallel disk systems require parallel file system software to avoid performance-limiting bottlenecks. We discuss cache management techniques that can be used in a parallel file system implementation. We examine several writeback policies, and give results of experiments that test their performance.
Practical Prefetching Techniques For Parallel File Systems, David Kotz, Carla Schlatter Ellis
Practical Prefetching Techniques For Parallel File Systems, David Kotz, Carla Schlatter Ellis
Dartmouth Scholarship
Parallel disk subsystems have been proposed as one way to close the gap between processor and disk speeds. In a previous paper we showed that prefetching and caching have the potential to deliver the performance benefits of parallel file systems to parallel applications. In this paper we describe experiments with practical prefetching policies, and show that prefetching can be implemented efficiently even for the more complex parallel file access patterns. We test these policies across a range of architectural parameters.
Selective Decay And Coherent Vortices In Two-Dimensional Incompressible Turbulence, William H. Matthaeus, W. Troy Stribling, Daniel Martinez, Sean Oughton, David Montgomery
Selective Decay And Coherent Vortices In Two-Dimensional Incompressible Turbulence, William H. Matthaeus, W. Troy Stribling, Daniel Martinez, Sean Oughton, David Montgomery
Dartmouth Scholarship
Numerical solution of two-dimensional incompressible hydrodynamics shows that states of a near-minimal ratio of enstrophy to energy can be attained in times short compared with the flow decay time, confirming the simplest turbulent selective decay conjecture, and suggesting that coherent vortex structures do not terminate nonlinear processes. After all possible vortex mergers occur, the vorticity attains a particlelike character, suggested by the late-time similarity of the streamlines to Ewald potential contours.
The Fracture Of Ice On Scales Large And Small: Arctic Leads And Wing Cracks, E. M. Schulson, W. D. Hibler
The Fracture Of Ice On Scales Large And Small: Arctic Leads And Wing Cracks, E. M. Schulson, W. D. Hibler
Dartmouth Scholarship
From observations and calculations of crack patterns in ice, it is suggested that a similar mechanism may account for cracking over a wide range of scales.
The Thermal Response Of Downhill Skis, S. C. Colbeck, G. C. Warren
The Thermal Response Of Downhill Skis, S. C. Colbeck, G. C. Warren
Dartmouth Scholarship
No abstract provided.
Prefetching And Caching Techniques In File Systems For Mimd Multiprocessors, David F. Kotz
Prefetching And Caching Techniques In File Systems For Mimd Multiprocessors, David F. Kotz
Dartmouth Scholarship
The increasing speed of the most powerful computers, especially multiprocessors, makes it difficult to provide sufficient I/O bandwidth to keep them running at full speed for the largest problems. Trends show that the difference in the speed of disk hardware and the speed of processors is increasing, with I/O severely limiting the performance of otherwise fast machines. This widening access-time gap is known as the “I/O bottleneck crisis.” One solution to the crisis, suggested by many researchers, is to use many disks in parallel to increase the overall bandwidth. \par This dissertation studies some of the file system issues needed …
Multiphoton Ionization Of Nitrobenzene In Non-Aqueous Solutions: Characterization Of The Cation And Ion-Molecule Chemistry, G. Siuzdak, J. J. Belbruno
Multiphoton Ionization Of Nitrobenzene In Non-Aqueous Solutions: Characterization Of The Cation And Ion-Molecule Chemistry, G. Siuzdak, J. J. Belbruno
Dartmouth Scholarship
The phenoxy cation has been generated in polar and nonpolar solutions by multiphoton ionization of nitrobenzene using nanosecond pulses of 266 nm and 355 nm light. The ions have been characterized by pulsed conductivity (ion mobility) measurements and transient absorption spectroscopy. The involvement of the phenoxy ion in ion-molecule chemistry with either neutral solute or solvent molecules has also been observed and the photochemical products and quantum yields of the ion-molecule products are presented and compared with the neutral photochemistry results.
Moore Cohomology, Principal Bundles, And Actions Of Groups On C*-Algebras, Ian Raeburn, Dana P. Williams
Moore Cohomology, Principal Bundles, And Actions Of Groups On C*-Algebras, Ian Raeburn, Dana P. Williams
Dartmouth Scholarship
In recent years both topological and algebraic invariants have been associated to group actions on C*-algebras. Principal bundles have been used to describe the topological structure of the spectrum of crossed products [18, 19], and as a result we now know that crossed products of even the very nicest non-commutative algebras can be substantially more complicated than those of commutative algebras [19, 5]. The algebraic approach involves group cohomological invariants, and exploits the associated machinery to classify group actions on C*-algebras; this originated in [2], and has been particularly successful for actions of R and tori ([19; Section 4], [21]). …
Uv Observations Of The Cool Dbqa5 White Dwarf Lds 678a - Limits On The Atmospheric Composition, Pressure Shift, And Gravitational Redshift Derived From C I 2479, Terry D. Oswalt, Edward M. Sion, Gordon Hammond, Gerard Vauclair, James W. Liebert, Gary Wegner
Uv Observations Of The Cool Dbqa5 White Dwarf Lds 678a - Limits On The Atmospheric Composition, Pressure Shift, And Gravitational Redshift Derived From C I 2479, Terry D. Oswalt, Edward M. Sion, Gordon Hammond, Gerard Vauclair, James W. Liebert, Gary Wegner
Dartmouth Scholarship
A high-resolution ultraviolet spectrum of the helium-rich degenerate LDS 678A, obtained with the International Ultraviolet Explorer (IUE) satellite, is presented. LDS 678A is the coolest metallic line degenerate (DQ or DZ) yet observed with the IUE echelle. These observations provide a detailed line profile of the strong C I 2479 absorption line and equivalent width W2479 = 2.35 + or - 0.06 A from which theoretical profile fits yield a carbon abundance of log C/He = (-6.7 + or- 0.2). The presence of carbon in a He-rich atmosphere lends credence to the notion that LDS 678A is a transitional case …