14,360 research outputs found
Evaluating the reliability of NAND multiplexing with PRISM
Probabilistic-model checking is a formal verification technique for analyzing the reliability and performance of systems exhibiting stochastic behavior. In this paper, we demonstrate the applicability of this approach and, in particular, the probabilistic-model-checking tool PRISM to the evaluation of reliability and redundancy of defect-tolerant systems in the field of computer-aided design. We illustrate the technique with an example due to von Neumann, namely NAND multiplexing. We show how, having constructed a model of a defect-tolerant system incorporating probabilistic assumptions about its defects, it is straightforward to compute a range of reliability measures and investigate how they are affected by slight variations in the behavior of the system. This allows a designer to evaluate, for example, the tradeoff between redundancy and reliability in the design. We also highlight errors in analytically computed reliability bounds, recently published for the same case study
Odd Parity and Line Nodes in Heavy Fermion Superconductors
Group theory arguments have demonstrated that a general odd parity order
parameter cannot have line nodes in the presence of spin-orbit coupling. In
this paper, it is shown that these arguments do not hold on the
zone face of a hexagonal close packed lattice. In particular, three of the six
odd parity representations vanish identically on this face. This has potential
relevance to the heavy fermion superconductor .Comment: 5 pages, revte
The role of community acceptance in planning outcomes for onshore wind and solar farms: An energy justice analysis
The deployment of renewable technologies as part of climate mitigation strategies have provoked a range of responses from various actors, bringing public acceptance to the forefront of energy debates. A key example is the reaction of communities when renewable projects are proposed in their local areas. This paper analyses the effect that community acceptance has had on planning applications for onshore wind and solar farms in Great Britain between 1990 and 2017. It does this by compiling a set of indicators for community acceptance and testing their association with planning outcomes using binomial logistic regression. It identifies 12 variables with statistically significant effects: 4 for onshore wind, 4 for solar farms, and 4 spanning both. For both technologies, the visibility of a project, its installed capacity, the social deprivation of the area, and the year of the application are significant. The paper draws conclusions from these results for community acceptance and energy justice, and discusses the implications for energy decision-making
Modular and reconfigurable transient modeling and simulation design support tool for MEE/MEA power systems
There is a well-recognised need for robust simulation tools to support the design and evaluation of future More-Electric Engine and Aircraft (MEE/MEA) design concepts. Design options for these systems are increasingly complex, and normally include multiple power electronics converter topologies and machine drive units. In order to identify the most promising set of system configurations, a large number of technology variants need to be rapidly evaluated. This paper will describe a method of MEE/MEA system design with the use of a newly developed transient modeling, simulation and testing tool aimed at accelerating the identification process of optimal components, testing novel technologies and finding key solutions at an early development stage. The developed tool is a Matlab/Simulink library consisting of functional sub-system units, which can be rapidly integrated to build complex system architecture models
Onset of phase correlations in YBa2Cu3O{7-x} as determined from reversible magnetization measurements
Isofield magnetization curves are obtained and analyzed for three single
crystals of YBa2Cu3O{7-x}, ranging from optimally doped to very underdoped, as
well as the BCS superconductor Nb, in the presence of magnetic fields applied
both parallel and perpendicular to the planes. Near Tc, the magnetization
exhibits a temperature dependence \sqrt{M} [Ta(H)-T]^m. In accordance with
recent theories, we associated Ta(H) with the onset of coherent phase
fluctuations of the superconducting order parameter. For Nb and optimally doped
YBaCuO, Ta(H) is essentially identical to the mean-field transition line Tc(H).
The fitting exponent m=0.5 takes its mean-field value for Nb, and varies just
slightly from 0.5 for optimally doped YBaCuO. However, underdoped YBCO samples
exhibit anomalous behavior, with Ta(H)>Tc for H applied parallel to the c axis,
suggesting that the magnetization is probing a region of temperatures above Tc
where phase correlations persist. In this region, the fitting exponent falls in
the range 0.5 < m < 0.8 for H\parallel c, compared with m~0. for $H\parallel ab
planes. The results are interpreted in terms of an anisotropic pairing symmetry
of the order parameter: d-wave along the ab planes and s-wave along the c axis.Comment: 5 pages, 4 figure
Hemp a war crop for Iowa
Hemp is an annual crop grown for the production of fiber. It is sown in the spring like small grain and produces a thick stand of slender unbranched stalks, growing usually to a height of 6 to 10 feet. The fiber is found extending the length of the stalk, between the thin bark on the outside and the woody central pith on the inside. To obtain, the fiber the stalks are retted (partially decomposed) and then put through machines that separate the fiber from the rest of the stalk.
Although hemp has been grown in the United States since early colonial days the acreage of this crop has not been very extensive. Due primarily to competition from cotton, jute, sisal and abaca (Manila fiber) domestic hemp production declined until a low of 1,200 acres was reached in 1933. Since 1939, because of the stimulation of an increased demand due to war conditions, production has again increased. In 1942 there were about 7,500 acres grown for fiber in Wisconsin, 5,000 in Kentucky, 600 in Minnesota and 500 in Illinois
Temperature-dependent quantum pair potentials and their application to dense partially ionized hydrogen plasmas
Extending our previous work \cite{filinov-etal.jpa03ik} we present a detailed
discussion of accuracy and practical applications of finite-temperature
pseudopotentials for two-component Coulomb systems. Different pseudopotentials
are discussed: i) the diagonal Kelbg potential, ii) the off-diagonal Kelbg
potential iii) the {\em improved} diagonal Kelbg potential, iv) an effective
potential obtained with the Feynman-Kleinert variational principle v) the
``exact'' quantum pair potential derived from the two-particle density matrix.
For the {\em improved} diagonal Kelbg potential a simple temperature dependent
fit is derived which accurately reproduces the ``exact'' pair potential in the
whole temperature range. The derived pseudopotentials are then used in path
integral Monte Carlo (PIMC) and molecular dynamics (MD) simulations to obtain
thermodynamical properties of strongly coupled hydrogen. It is demonstrated
that classical MD simulations with spin-dependent interaction potentials for
the electrons allow for an accurate description of the internal energy of
hydrogen in the difficult regime of partial ionization down to the temperatures
of about K. Finally, we point out an interesting relation between the
quantum potentials and effective potentials used in density functional theory.Comment: 18 pages, 11 figure
Gravitational quasinormal modes for Anti-de Sitter black holes
Quasinormal mode spectra for gravitational perturbations of black holes in
four dimensional de Sitter and anti-de Sitter space are investigated. The
anti-de Sitter case is relevant to the ADS-CFT correspondence in superstring
theory. The ADS-CFT correspondence suggests a prefered set of boundary
conditions.Comment: 12 pages, 6 figures in ReVTe
Heat Transport and the Nature of the Order Parameter in Superconducting
Recent thermal conductivity data on the heavy fermion superconductor
have been interpreted as offering support for an model of the order
parameter as opposed to an model. In this paper, we analyze this issue
from a theoretical standpoint including the detailed effects of Fermi surface
and gap anisotropy. Our conclusion is that although current data put strong
constraints on the gap anisotropy, they cannot definitively distinguish between
these two models. Measurements on samples of varying quality could be decisive
in this regard, however.Comment: 8 pages, revtex, 15 uunencoded postscript figure
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