53,617 research outputs found
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Variable domain transformation for linear PAC analysis of mixed-signal systems
This paper describes a method to perform linear AC analysis on mixed-signal systems which appear strongly nonlinear in the voltage domain but are linear in other variable domains. Common circuits like phase/delay-locked loops and duty-cycle correctors fall into this category, since they are designed to be linear with respect to phases, delays, and duty-cycles of the input and output clocks, respectively. The method uses variable domain translators to change the variables to which the AC perturbation is applied and from which the AC response is measured. By utilizing the efficient periodic AC (PAC) analysis available in commercial RF simulators, the circuit’s linear transfer function in the desired variable domain can be characterized without relying on extensive transient simulations. Furthermore, the variable domain translators enable the circuits to be macromodeled as weakly-nonlinear systems in the chosen domain and then converted to voltage-domain models, instead of being modeled as strongly-nonlinear systems directly
Reliable multi-hop routing with cooperative transmissions in energy-constrained networks
We present a novel approach in characterizing the optimal reliable multi-hop virtual multiple-input single-output (vMISO) routing in ad hoc networks. Under a high node density regime, we determine the optimal cardinality of the cooperation
sets at each hop on a path minimizing the total energy cost per transmitted bit. Optimal cooperating set cardinality curves are derived, and they can be used to determine the optimal routing strategy based on the required reliability, transmission power, and path loss coefficient. We design a new greedy geographical
routing algorithm suitable for vMISO transmissions, and demonstrate the applicability of our results for more general networks
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The Temporal Efficiency of SO2 Emissions Trading
The Temporal Efficiency of SO2 Emissions Tradin
Research and Education in Computational Science and Engineering
Over the past two decades the field of computational science and engineering
(CSE) has penetrated both basic and applied research in academia, industry, and
laboratories to advance discovery, optimize systems, support decision-makers,
and educate the scientific and engineering workforce. Informed by centuries of
theory and experiment, CSE performs computational experiments to answer
questions that neither theory nor experiment alone is equipped to answer. CSE
provides scientists and engineers of all persuasions with algorithmic
inventions and software systems that transcend disciplines and scales. Carried
on a wave of digital technology, CSE brings the power of parallelism to bear on
troves of data. Mathematics-based advanced computing has become a prevalent
means of discovery and innovation in essentially all areas of science,
engineering, technology, and society; and the CSE community is at the core of
this transformation. However, a combination of disruptive
developments---including the architectural complexity of extreme-scale
computing, the data revolution that engulfs the planet, and the specialization
required to follow the applications to new frontiers---is redefining the scope
and reach of the CSE endeavor. This report describes the rapid expansion of CSE
and the challenges to sustaining its bold advances. The report also presents
strategies and directions for CSE research and education for the next decade.Comment: Major revision, to appear in SIAM Revie
Characterizing AGB stars in Wide-field Infrared Survey Explorer (WISE) bands
Since asymptotic giant branch (AGB) stars are bright and extended infrared
objects, most Galactic AGB stars saturate the Wide-field Infrared Survey
Explorer (WISE) detectors and therefore the WISE magnitudes that are restored
by applying point-spread-function fitting need to be verified. Statistical
properties of circumstellar envelopes around AGB stars are discussed on the
basis of a WISE AGB catalog verified in this way. We cross-matched an AGB star
sample with the WISE All-Sky Source Catalog and the Two Mircon All Sky Survey
catalog. Infrared Space Observatory (ISO) spectra of a subsample of WISE AGB
stars were also exploited. The dust radiation transfer code DUSTY was used to
help predict the magnitudes in the W1 and W2 bands, the two WISE bands most
affected by saturation, for calibration purpose, and to provide physical
parameters of the AGB sample stars for analysis. DUSTY is verified against the
ISO spectra to be a good tool to reproduce the spectral energy distributions of
these AGB stars. Systematic magnitude-dependent offsets have been identified in
WISE W1 and W2 magnitudes of the saturated AGB stars, and empirical calibration
formulas are obtained for them on the basis of 1877 (W1) and 1558 (W2) AGB
stars that are successfully fit with DUSTY. According to the calibration
formulae, the corrections for W1 at 5 mag and W2 at 4 mag are and
0.217 mag, respectively. In total, we calibrated the W1/W2 magnitudes of
2390/2021 AGB stars. The model parameters from the DUSTY and the calibrated
WISE W1 and W2 magnitudes are used to discuss the behavior of the WISE
color-color diagrams of AGB stars. The model parameters also reveal that O-rich
AGB stars with opaque circumstellar envelopes are much rarer than opaque C-rich
AGB stars toward the anti-Galactic center direction, which we attribute to the
metallicity gradient of our Galaxy.Comment: 9 pages in two column format, 7 figures, accepted for publication in
A&
Characterizing and Subsetting Big Data Workloads
Big data benchmark suites must include a diversity of data and workloads to
be useful in fairly evaluating big data systems and architectures. However,
using truly comprehensive benchmarks poses great challenges for the
architecture community. First, we need to thoroughly understand the behaviors
of a variety of workloads. Second, our usual simulation-based research methods
become prohibitively expensive for big data. As big data is an emerging field,
more and more software stacks are being proposed to facilitate the development
of big data applications, which aggravates hese challenges. In this paper, we
first use Principle Component Analysis (PCA) to identify the most important
characteristics from 45 metrics to characterize big data workloads from
BigDataBench, a comprehensive big data benchmark suite. Second, we apply a
clustering technique to the principle components obtained from the PCA to
investigate the similarity among big data workloads, and we verify the
importance of including different software stacks for big data benchmarking.
Third, we select seven representative big data workloads by removing redundant
ones and release the BigDataBench simulation version, which is publicly
available from http://prof.ict.ac.cn/BigDataBench/simulatorversion/.Comment: 11 pages, 6 figures, 2014 IEEE International Symposium on Workload
Characterizatio
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