334,076 research outputs found
Joint Cache Partition and Job Assignment on Multi-Core Processors
Multicore shared cache processors pose a challenge for designers of embedded
systems who try to achieve minimal and predictable execution time of workloads
consisting of several jobs. To address this challenge the cache is statically
partitioned among the cores and the jobs are assigned to the cores so as to
minimize the makespan. Several heuristic algorithms have been proposed that
jointly decide how to partition the cache among the cores and assign the jobs.
We initiate a theoretical study of this problem which we call the joint cache
partition and job assignment problem.
By a careful analysis of the possible cache partitions we obtain a constant
approximation algorithm for this problem. For some practical special cases we
obtain a 2-approximation algorithm, and show how to improve the approximation
factor even further by allowing the algorithm to use additional cache. We also
study possible improvements that can be obtained by allowing dynamic cache
partitions and dynamic job assignments.
We define a natural special case of the well known scheduling problem on
unrelated machines in which machines are ordered by "strength". Our joint cache
partition and job assignment problem generalizes this scheduling problem which
we think is of independent interest. We give a polynomial time algorithm for
this scheduling problem for instances obtained by fixing the cache partition in
a practical case of the joint cache partition and job assignment problem where
job loads are step functions
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TDLAS Detection of propane and butane gas over the near-infrared wavelength range from 1678nm to 1686nm
It is important in the petrochemical industry that there are high sensitivity, high accuracy, low-power consumption and intrinsically safe methods for the detection of propane, butane and their gas mixtures, to provide early warning of potential explosion hazards during both storage and transportation of oil and gas. This paper proposes a 'proof of principle' method for the detection of propane and butane using a Tunable Diode Laser Absorption Spectroscopy (TDLAS) technique over the near-infrared wavelength range from 1678nm to 1686nm. This method is relatively inexpensive to implement and is thus more practical, compared with detection methods using wavelengths further into the infra-red, near 3.3μm. The minimum detectable concentration was found to be low as 300ppm for propane or butane. Importantly, the relative measurement errors were all below 3% LEL, which meets the requirements from the petrochemical and oil-gas storage and transportation industries for a field-based system for monitoring of combustible gases
Revisiting the hot matter in the center of gamma-ray bursts and supernova
Hot matter with nucleons can be produced in the inner region of the
neutrino-dominated accretion flow in gamma-ray bursts or during the
proto-neutron star birth in successful supernova. The composition and equation
of state of the matter depend on the dynamic equilibrium under various
neutrino opacities. The strong interaction between nucleons may also play an
important role. We plan to extend the previous studies by incorporating these
two aspects in our model. The modification of the -equilibrium condition
from neutrino optically thin to thick has been modeled by an equilibrium factor
ranging between the neutrino-freely-escaping case and the
neutrino-trapped case. We employ the microscopic Brueckner-Hartree-Fock
approach extended to the finite temperature regime to study the interacting
nucleons. We show that the composition and chemical potentials of the hot
nuclear matter for different densities and temperatures at each stage of
equilibrium. We also compare our realistic equation of states with
those of the free gas model. We find the neutrino opacity and the strong
interaction between nucleons are important for the description and should be
taken into account in model calculations.Comment: accepted Astronomy & Astrophysics (2013
Flow Induced by the Impulsive Motion of an Infinite Flat Plate in a Dusty Gas
Flow Induced by the Impulsive Motion of an Immite Flat Plate in a Dusty Gas. The problem of
flow induced by an infinite flat plate suddenly set into motion parallel to its own plane in an incompressible
dusty gas is of considerable physical interest in its own right as well as because of its close relation to the
non-linear, steady (constant-pressure) laminar boundary layer. Its solution provides complete and exact
information about modifications of the boundary layer growth and skin friction due to particle-fluid
interaction. Moreover, it provides a basis for judging the accuracy of approximations which have been
employed in more complex problems of viscous fluid-particle motion. The uncoupled thermal Rayleigh
problem for small relative temperature differences is directly inferred and this answers questions about the
modifications of the surface heat transfer rate and about the possibility of similarity with the velocity
boundary layer. Similarity is possible when, in addition to a Prandtl number of unity, the streamwise
relaxation processes are also similar
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Fabrication of a high sensitive Ag-nanoparticle substrate and its application to the detection of toxic substances
Surface Enhanced Raman Scattering (SERS) is typically observed with the substrate in a liquid medium and it has been proposed as a promising technique for detecting low levels of pollutants in liquids. A technique is presented for self-assembly to immobilize Ag nanoparticles (Ag-NPs), with diameters ranging from 100 to 800nm on a solid support. Experimental results have been obtained through experiments using Ag-NPs active substrates to detect Rhodamine 6G (R6G) and crystal violet in the deionized water. Further, the SERS spectrum and Raman spectrum of phoxim were also measured, showing the enhancement in the performance of the active substrate as a result
An advanced meshless method for time fractional diffusion equation
Recently, because of the new developments in sustainable engineering and renewable energy, which are usually governed by a series of fractional partial differential equations (FPDEs), the numerical modelling and simulation for fractional calculus are attracting more and more attention from researchers. The current dominant numerical method for modeling FPDE is Finite Difference Method (FDM), which is based on a pre-defined grid leading to inherited issues or shortcomings including difficulty in simulation of problems with the complex problem domain and in using irregularly distributed nodes. Because of its distinguished advantages, the meshless method has good potential in simulation of FPDEs. This paper aims to develop an implicit meshless collocation technique for FPDE. The discrete system of FPDEs is obtained by using the meshless shape functions and the meshless collocation formulation. The stability and convergence of this meshless approach are investigated theoretically and numerically. The numerical examples with regular and irregular nodal distributions are used to validate and investigate accuracy and efficiency of the newly developed meshless formulation. It is concluded that the present meshless formulation is very effective for the modeling and simulation of fractional partial differential equations
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