24,334 research outputs found
Quantum Resonances of Weakly Linked, Mesoscopic, Superconducting Dots
We examine quantum properties of mesoscopic, Josephson coupled
superconducting dots, in the limit that charging effects and quantization of
energy levels within the dots are negligible, but quasi-particle transmission
into the weak link is not. We demonstrate that quasi-particle resonances lead
to current-phase relations, which deviate markedly from those of weak links
connecting macroscopic superconductors. Results for the steady state dc
Josephson current of two coupled dots are presented.Comment: Tex, 3 figures available on request to [email protected] (Andy
Martin
Emergent Time and the M5-Brane
We consider the maximal super-Yang-Mills theory in 5 Euclidean dimensions
with SO(5) R-symmetry and 16 supersymmetries. We argue that the strong coupling
limit of this theory (with a possible UV completion) has an emergent time
dimension and gives a description of the 5+1 dimensional Lorentz invariant
(2,0) theory of the M5-brane, compactified on a timelike circle with radius
R=g^2/4\pi^2 . Our discussion involves issues of quantization of Euclidean
theories without time.Comment: 1+40 page
Generalized disjunction decomposition for the evolution of programmable logic array structures
Evolvable hardware refers to a self reconfigurable electronic circuit, where the circuit configuration is under the control of an evolutionary algorithm. Evolvable hardware has shown one of its main deficiencies, when applied to solving real world applications, to be scalability. In the past few years several techniques have been proposed to avoid and/or solve this problem. Generalized disjunction decomposition (GDD) is one of these proposed methods. GDD was successful for the evolution of large combinational logic circuits based on a FPGA structure when used together with bi-directional incremental evolution and with (1+ë) evolution strategy. In this paper a modified generalized disjunction decomposition, together with a recently introduced multi-population genetic algorithm, are implemented and tested for its scalability for solving large combinational logic circuits based on Programmable Logic Array (PLA) structures
Non-destructive ultrasonic measurements of case depth
Two ultrasonic methods for nondestructive measurements of the depth of a case-hardened layer in steel are described. One method involves analysis of ultrasonic waves diffused back from the bulk of the workpiece. The other method involves finding the speed of propagation of ultrasonic waves launched on the surface of the work. Procedures followed in the two methods for measuring case depth are described
Scottish social survey data, past present and future:Does Scotland need its own data strategy?
The UK now has a National Data Strategy. In this paper we explore whether or not in addition Scotland needs its own specific data strategy. This paper is intended to be a ‘think piece’ or critical essay, the motivation being to encourage debate about Scottish social survey data. Post-devolution, with the emergence of new forms of governance and new institutional arrangements, the political desire to research Scotland in the 21st Century has been brought into sharper resolution. Social and economic life in Scotland shares both similarities and differences with life south of the border. It is important that these characteristics are correctly identified with empirical data rather than simply being assumed. Scotland is a small territory with a good social science tradition and a healthy research sector. There is an increasing amount of survey data collecting measures relating to social and economic life in Scotland. These include both United Kingdom or Great Britain based surveys with a Scottish component, and Scotland focussed surveys. In this paper we outline a number of key issues relating to Scottish social science data resources. We provide a number of critical recommendations for social science data collection in Scotland. Finally, we examine the potential benefits of a comprehensive data strategy
M-Theory and Hypercharge
We discuss the possibility that the electro-weak and strong interactions
arise as the low energy effective description of branes in M-theory. As a step
towards constructing such a model we show how one can naturally obtain
SU(N_1)\times SU(N_2)\times U(1) gauge theories from branes, including matter
in the bi-fundamental representation of SU(N_1)\times SU(N_2) which are
fractionally charged under U(1).Comment: 29 pages Phyzzx. Two figure
Generalized disjunction decomposition for evolvable hardware
Evolvable hardware (EHW) refers to self-reconfiguration hardware design, where the configuration is under the control of an evolutionary algorithm (EA). One of the main difficulties in using EHW to solve real-world problems is scalability, which limits the size of the circuit that may be evolved. This paper outlines a new type of decomposition strategy for EHW, the “generalized disjunction decomposition” (GDD), which allows the evolution of large circuits. The proposed method has been extensively tested, not only with multipliers and parity bit problems traditionally used in the EHW community, but also with logic circuits taken from the Microelectronics Center of North Carolina (MCNC) benchmark library and randomly generated circuits. In order to achieve statistically relevant results, each analyzed logic circuit has been evolved 100 times, and the average of these results is presented and compared with other EHW techniques. This approach is necessary because of the probabilistic nature of EA; the same logic circuit may not be solved in the same way if tested several times. The proposed method has been examined in an extrinsic EHW system using theevolution strategy. The results obtained demonstrate that GDD significantly improves the evolution of logic circuits in terms of the number of generations, reduces computational time as it is able to reduce the required time for a single iteration of the EA, and enables the evolution of larger circuits never before evolved. In addition to the proposed method, a short overview of EHW systems together with the most recent applications in electrical circuit design is provided
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