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

Significant parameters of mining properties in arctic and subarctic areas of North America

Editors: Bruce W. Campbell and John J. DiMarchiThis paper is a review of those factors unique to mining in the Arctic and subarctic. The information was developed from an exhaustive Literature search and personal visits to several northern mines in North America. The intent is to present a broad overview of many of these factors, to identify and stimulate consideration of parameters that are likely to be overlooked by companies end persons wlthout p rior arctic experience. Topics of discussion include exploration, cold weather plant design, blasting in permafrost, living conditions and employees relations. The appendices are a brief discussion of a number of the arctic and subarctic operations in North America. In brief, minlng in northern regions is practical provided the deposit has sufficient value to support the higher construction, transportation and operating costs associated with the remoteness and cold weather. Hiring and retaining good employees and integrating the native labor force into the operation have proven to be the most difficult problems. Equipment and plant operation are problems more easily solved.This report is a revised and edited form of the report by the same authors and originally titled "Identification of and Significant Parameters of Mining Properties located in Arctic and Subarctic areas of Norther America", under U.S. Bureau of Mines Contract No. S0144117

The Development of British Military Masculinities through Symbolic Resources

Within military culture there is a protected version of masculinity. The theory of symbolic resources (Zittoun, Duveen, Gillespie, Ivinson & Psaltis, 2003) recognises that people are positioned within different symbolic streams in the socio-cultural world, in which they can be displaced or can relocate themselves (Benson, 2001; Duveen, 2001). So an individual entering the military is relocating him or herself from a civilian socio-cultural world to a military one. 29 semi-structured individual interviews and three focus groups (each comprising three individuals) with male and female military personnel in Britain were conducted. Participants included Royal Marine, Army and Royal Air Force personnel and were of a variety of ranks. In accordance with the theory of symbolic resources, the unit of analysis for psychological development is the unit rupture-irruption of certainty-transition. This implies a process that leads to a new form of stability. This process is that which military personnel undertake in order for that which is uncertain and unfamiliar when they begin their training to become certain and familiar. Through focusing on the rupture that takes place during the training phase within an individual’s military career, one can explore how through symbolic resources, military masculinities develop.Symbolic resources, Masculinities, Military culture, identity

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 the$(1 + lambda)$evolution 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

Partial inner product spaces: Some categorical aspects

We make explicit in terms of categories a number of statements from the theory of partial inner product spaces (PIP spaces) and operators on them. In particular, we construct sheaves and cosheaves of operators on certain PIP spaces of practical interest.Comment: 21 page

Crossed conductance in FSF double junctions: role of out-of-equilibrium populations

We discuss a model of Ferromagnet / Superconductor / Ferromagnet (FSF) double junction in which the quasiparticles are not in equilibrium with the condensate in a region of the superconductor containing the two FS contacts. The role of geometry is discussed, as well as the role of a small residual density of states within the superconducting gap, that allows a sequential tunneling crossed current. With elastic quasiparticle transport and the geometry with lateral contacts, the crossed conductances in the sequential tunneling channel are almost equal in the normal and superconducting phases, if the distance between the FS interfaces is sufficiently small. The sequential tunneling and spatially separated processes (the so-called crossed Andreev reflection and elastic cotunneling processes) lead to different signs of the crossed current in the antiparallel alignment for tunnel interfaces.Comment: 8 pages, 4 figure

Analysis of Possible Quantum Metastable States in Ballistic Graphene-based Josephson Junctions

Graphene is a relatively new material (2004) made of atomic layers of carbon arranged in a honeycomb lattice. Josephson junction devices are made from graphene by depositing two parallel superconducting leads on a graphene flake. These devices have hysteretic current-voltage characteristics with a supercurrent branch and Shapiro steps appear when irradiated with microwaves. These properties motivate us to investigate the presence of quantum metastable states similar to those found in conventional current-biased Josephson junctions. We present work investigating the nature of these metastable states for ballistic graphene Josephson junctions. We model the effective Washboard potential for these devices and estimate parameters, such as energy level spacing and critical currents, to deduce the design needed to observe metastable states. We propose devices consisting of a parallel on-chip capacitor and suspended graphene. The capacitor is needed to lower the energy level spacing down to the experimentally accessible range of 1-20 GHz. The suspended graphene helps reduce the noise that may otherwise come from two-level states in the insulating oxide layer. Moreover, back-gate voltage control of its critical current introduces another knob for quantum control. We will also report on current experimental progress in the area of fabrication of this proposed device.Comment: 4 pages, 5 figures, Accepted for publication in IEEE Transactions on Applied Superconductivity from ASC 2010. Additional figures, additional calculation

A novel genetic algorithm for evolvable hardware

Evolutionary algorithms are used for solving search and optimization problems. A new field in which they are also applied is evolvable hardware, which refers to a self-configurable electronic system. However, evolvable hardware is not widely recognized as a tool for solving real-world applications, because of the scalability problem, which limits the size of the system that may be evolved. In this paper a new genetic algorithm, particularly designed for evolving logic circuits, is presented and tested for its scalability. The proposed algorithm designs and optimizes logic circuits based on a Programmable Logic Array (PLA) structure. Furthermore it allows the evolution of large logic circuits, without the use of any decomposition techniques. The experimental results, based on the evolution of several logic circuits taken from three different benchmarks, prove that the proposed algorithm is very fast, as only a few generations are required to fully evolve the logic circuits. In addition it optimizes the evolved circuits better than the optimization offered by other evolutionary algorithms based on a PLA and FPGA structures