9,875 research outputs found
Neutrino Interactions in Octet Baryon Matter
Neutrino processes caused by the neutral current are studied in octet baryon
matter. Previous confusion about the baryonic matrix elements of the neutral
current interaction is excluded, and a correct table for them improved by
consideration of the proton spin problem is presented instead.Comment: 6 page
Protoneutron Stars with Kaon Condensation and their Delayed Collapse
Properties of protoneutron stars are discussed in the context of kaon
condensation. Thermal and neutrino trapping effects are very important
ingredients to study them. By solving the TOV equation, we discuss the static
properties of protoneutron stars and the possibility of the delayed collapse
during their evolution.Comment: 33pages,15 figures, accepted for publication in Nucl. Phys.
Residual stress development and evolution in two-phase crystalline material: a discrete dislocation study
Crystalline materials undergo heterogeneous deformation upon the application of external load, which results in the development of incompatible elastic strains in the material as soon as the load is removed. The presence of heterogeneous distribution of elastic strains in the absence of any form of external load results in the building up of stresses referred to as residual stresses. The heterogeneity of strain is attributed either to the presence of multiple phases or to the orientation gradients across the sample volume. This paper is an endeavour to model the presence of second phase in a two-dimensional discrete dislocation dynamics framework, which already contains constitutive rules to include three-dimensional mechanisms, such as line tension and dynamic junction formation. The model is used to investigate residual stress development in single crystals subjected to plane strain loading and then subsequently unloaded to study residual stresses. The dislocation accumulation around the second phase and its effect on the mechanical properties is studied. The orientation dependence of residual stresses as a function of the underlying defect substructure has also been explored. A variety of results are obtained. In particular, the development of stresses as a function of underlying defect substructure is also presented and found to depend upon the orientation of the crystal
Noise-Adaptive Compiler Mappings for Noisy Intermediate-Scale Quantum Computers
A massive gap exists between current quantum computing (QC) prototypes, and
the size and scale required for many proposed QC algorithms. Current QC
implementations are prone to noise and variability which affect their
reliability, and yet with less than 80 quantum bits (qubits) total, they are
too resource-constrained to implement error correction. The term Noisy
Intermediate-Scale Quantum (NISQ) refers to these current and near-term systems
of 1000 qubits or less. Given NISQ's severe resource constraints, low
reliability, and high variability in physical characteristics such as coherence
time or error rates, it is of pressing importance to map computations onto them
in ways that use resources efficiently and maximize the likelihood of
successful runs.
This paper proposes and evaluates backend compiler approaches to map and
optimize high-level QC programs to execute with high reliability on NISQ
systems with diverse hardware characteristics. Our techniques all start from an
LLVM intermediate representation of the quantum program (such as would be
generated from high-level QC languages like Scaffold) and generate QC
executables runnable on the IBM Q public QC machine. We then use this framework
to implement and evaluate several optimal and heuristic mapping methods. These
methods vary in how they account for the availability of dynamic machine
calibration data, the relative importance of various noise parameters, the
different possible routing strategies, and the relative importance of
compile-time scalability versus runtime success. Using real-system
measurements, we show that fine grained spatial and temporal variations in
hardware parameters can be exploited to obtain an average x (and up to
x) improvement in program success rate over the industry standard IBM
Qiskit compiler.Comment: To appear in ASPLOS'1
Power consumption prediction in cloud data center using machine learning
The flourishing development of the cloud computing paradigm provides several services in the industrial business world. Power consumption by cloud data centers is one of the crucial issues for service providers in the domain of cloud computing. Pursuant to the rapid technology enhancements in cloud environments and data centers augmentations, power utilization in data centers is expected to grow unabated. A diverse set of numerous connected devices, engaged with the ubiquitous cloud, results in unprecedented power utilization by the data centers, accompanied by increased carbon footprints. Nearly a million physical machines (PM) are running all over the data centers, along with (5 – 6) million virtual machines (VM). In the next five years, the power needs of this domain are expected to spiral up to 5% of global power production. The virtual machine power consumption reduction impacts the diminishing of the PM’s power, however further changing in power consumption of data center year by year, to aid the cloud vendors using prediction methods. The sudden fluctuation in power utilization will cause power outage in the cloud data centers. This paper aims to forecast the VM power consumption with the help of regressive predictive analysis, one of the Machine Learning (ML) techniques. The potency of this approach to make better predictions of future value, using Multi-layer Perceptron (MLP) regressor which provides 91% of accuracy during the prediction process
The viscosity radius in dilute polymer solutions: Universal behaviour from DNA rheology and Brownian dynamics simulations
The swelling of the viscosity radius, , and the universal
viscosity ratio, , have been determined experimentally for linear
DNA molecules in dilute solutions with excess salt, and numerically by Brownian
dynamics simulations, as a function of the solvent quality. In the latter
instance, asymptotic parameter free predictions have been obtained by
extrapolating simulation data for finite chains to the long chain limit.
Experiments and simulations show a universal crossover for and
from to good solvents in line with earlier observations
on synthetic polymer-solvent systems. The significant difference between the
swelling of the dynamic viscosity radius from the observed swelling of the
static radius of gyration, is shown to arise from the presence of hydrodynamic
interactions in the non-draining limit. Simulated values of and
are in good agreement with experimental measurements in synthetic
polymer solutions reported previously, and with the measurements in linear DNA
solutions reported here.Comment: 19 pages, 14 figures, two column, Supporting Information added, to
appear in Macromolecule
Shear thinning in dilute and semidilute solutions of polystyrene and DNA
The viscosity of dilute and semidilute unentangled DNA solutions, in steady
simple shear flow, has been measured across a range of temperatures and
concentrations. For polystyrene solutions, measurements of viscosity have been
carried out in the semidilute unentangled regime, while results of prior
experimental measurements in the dilute regime have been used for the purpose
of data analysis, and for comparison with the behaviour of DNA solutions.
Interpretation of the shear rate dependence of viscosity in terms of suitably
defined non-dimensional variables, is shown to lead to master plots,
independent of temperature and concentration, in each of the two concentration
regimes. In the case of semidilute unentangled solutions, defining the
Weissenberg number in terms of a concentration dependent large scale relaxation
time is found not to lead to data collapse across different concentrations. On
the other hand, the use of an alternative relaxation time, with the
concentration dependence of a single correlation blob, suggests the existence
of universal shear thinning behaviour at large shear rates.Comment: 24 pages, 13 figures, supplementary material (see ancillary
directory), to appear in Journal of Rheolog
Two-Hop Routing with Traffic-Differentiation for QoS Guarantee in Wireless Sensor Networks
This paper proposes a Traffic-Differentiated Two-Hop Routing protocol for
Quality of Service (QoS) in Wireless Sensor Networks (WSNs). It targets WSN
applications having different types of data traffic with several priorities.
The protocol achieves to increase Packet Reception Ratio (PRR) and reduce
end-to-end delay while considering multi-queue priority policy, two-hop
neighborhood information, link reliability and power efficiency. The protocol
is modular and utilizes effective methods for estimating the link metrics.
Numerical results show that the proposed protocol is a feasible solution to
addresses QoS service differenti- ation for traffic with different priorities.Comment: 13 page
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