The giant dispersion of critical currents in a superconductor with fractal clusters of a normal phase

The influence of fractal clusters of a normal phase on the dynamics of a magnetic flux trapped in a percolation superconductor is considered. The critical depinning current distribution and the current-voltage characteristics of fractal superconducting structures in the resistive state are determined for an arbitrary fractal dimension of the cluster boundaries. The interval of fractal dimensions is found in which the dispersion of critical currents exhibits unlimited growth. It is established that the fractality of clusters favors a decrease of the electric field arising during the magnetic flux motion, thus increasing the critical current value. The region featuring the giant dispersion of critical currents can be expected to provide for the maximum current-carrying capacity of a superconductor.     

Beam test of the CsI(Tl) calorimeter for the BELLE detector at the KEK-B factory

We studied the performance of a prototype electromagnetic calorimeter for the BELLE detector at the KEK proton synchrotron for an energy range of 0.25–3.5 GeV. The prototype consisted of an array of 6 × 5 CsI(Tl) crystals with 30 cm length (16.2 radiation lengths) and about 6 cm × 6 cm cross section. The scintillation light of each CsI(Tl) crystal was read out by two large-area PIN photodiodes and charge-sensitive preamplifiers attached at the rear face of the crystal. We measured the energy and position resolution for electrons and the e/π separation for two sets of matrix configurations: one corresponded to the center and the other to the edge of the barrel calorimeter. The overall performance measured by the test proves that the prototype calorimeter is satisfactory for the use in the BELLE detector.     

Taking into account the radiation pattern of a practical feed for a Luneberg lens

A method of taking into account the real feed radiation pattern for a Luneberg lens is proposed. According to this, the field of a feed with the given radiation pattern is expanded into series in spherical harmonics. Using this approach, it is possible to introduce the radiation patterns of real feeds into strict electrodynamic solution for a Luneberg lens, thus significantly refining a mathematical model of the antenna.     

Construction and verification of PLC-programs by LTL-specification

An approach to construction and verification of PLC-programs for discrete problems is proposed. For the specification of program behavior we use the linear-time temporal logic LTL. Programming is carried out in the ST-language according to an LTL-specification. The correctness analysis of an LTL-specification is carried out by the symbolic model checking tool Cadence SMV. A new approach to programming and verification of PLC-programs is shown by an example. For a discrete problem we give a ST-program, its LTL-specification and an SMV-model. The purpose of the article is to describe an approach to programming PLC, which would provide the possibility of PLC-program correctness analysis by the model checking method. Under the proposed approach the change of the value of each program variable is described by a pair of LTL-formulas. The first LTL-formula describes situations that increase the value of the corresponding variable, the second LTL-formula specifies conditions leading to a decrease of the variable value. The LTL-formulas (used for specification of the corresponding variable behavior) are constructive in the sense that they construct the PLC-program, which satisfies temporal properties expressed by these formulas. Thus, the programming of PLC is reduced to the construction of LTL-specification of the behavior of each program variable. In addition, an SMV-model of a PLC-program is constructed according to LTL-specification. Then, the SMV-model is analysed by the symbolic model checking tool Cadence SMV.     

On a reachability set of automation 3-counter machines

In this paper, we are concerned with the properties of a certain class of “automaton” counter machines in which each transition is defined nondeterministically according to the control states and irrespectively of the data being handled. Automaton counter machines are useful as a general means for demonstrating the undecidability of a series of problems that can be modeled by these machines, in particular, this being so for interacting coloring processes, which are useful in modeling the movement of data of various kinds between the components of a distributed system.     

Research support system for stochastic data processing

The paper describes a research support system named “MSM Tools” that can be used for stochastic modelling of real processes in various information systems and implements the heterogeneous computing paradigm. The proposed approach to data mining is based on method of moving separation of probability mixtures. To obtain statistical estimations of the unknown parameters of mixed probability models, the system implements several modifications of so-called EM algorithm (including grid modifications for the NVIDIA CUDA architecture) that are commonly used in such areas as pattern recognition, clustering, classification, processing of censored and/or truncated data. An example of real data analysis via “MSM Tools” service is given.     

A Newton-like finite element scheme for compressible gas flows

Semi-implicit and Newton-like finite element methods are developed for the stationary compressible Euler equations. The Galerkin discretization of the inviscid fluxes is potentially oscillatory and unstable. To suppress numerical oscillations, the spatial discretization is performed by a high-resolution finite element scheme based on algebraic flux correction. A multidimensional limiter of TVD type is employed. An important goal is the efficient computation of stationary solutions in a wide range of Mach numbers, which is a challenging task due to oscillatory correction factors associated with TVD-type flux limiters. A semi-implicit scheme is derived by a time-lagged linearization of the nonlinear residual, and a Newton-like method is obtained in the limit of infinite CFL numbers. Special emphasis is laid on the numerical treatment of weakly imposed characteristic boundary conditions. Numerical evidence for unconditional stability is presented. It is shown that the proposed approach offers higher accuracy and better convergence behavior than algorithms in which the boundary conditions are implemented in a strong sense.     

Next-Generation Grade and Survival Expression Biomarkers of Human Gliomas Based on Algorithmically Reconstructed Molecular Pathways

In gliomas, expression of certain marker genes is strongly associated with survival and tumor type and often exceeds histological assessments. Using a human interactome model, we algorithmically reconstructed 7494 new-type molecular pathways that are centered each on an individual protein. Each single-gene expression and gene-centric pathway activation was tested as a survival and tumor grade biomarker in gliomas and their diagnostic subgroups (IDH mutant or wild type, IDH mutant with 1p/19q co-deletion, MGMT promoter methylated or unmethylated), including the three major molecular subtypes of glioblastoma (proneural, mesenchymal, classical). We used three datasets from The Cancer Genome Atlas and the Chinese Glioma Genome Atlas, which in total include 527 glioblastoma and 1097 low grade glioma profiles. We identified 2724 such gene and 2418 pathway survival biomarkers out of total 17,717 genes and 7494 pathways analyzed. We then assessed tumor grade and molecular subtype biomarkers and with the threshold of AUC > 0.7 identified 1322/982 gene biomarkers and 472/537 pathway biomarkers. This suggests roughly two times greater efficacy of the reconstructed pathway approach compared to gene biomarkers. Thus, we conclude that activation levels of algorithmically reconstructed gene-centric pathways are a potent class of new-generation diagnostic and prognostic biomarkers for gliomas.     

Evaluation of shaping accuracy upon electrochemical machining of metals

This work investigates the influence of the pulse repetition frequency on the profile generated within pulse electrochemical dimensional machining of nickel foil using a cylindrical electrode tool. Geometrical criteria for the shaping accuracy characteristics are introduced. It has been demonstrated that, irrespectively of the criterion calculation method, the significant influence of the pulse repetition frequency on the shaping is observed. Herewith, the frequency variation makes it possible to determine the extreme criterion point corresponding to the best replication of the electrode tool. It is established that the variation of the pulse repetition frequency influences first of all the region of generation of the outer corner of the formed profile.     

ITER vacuum vessel: Design review and start of procurement process

The ITER vacuum vessel (VV) is one of the most critical components in the ITER project. It is on the critical path in the construction schedule and it is also a safety important class component (SIC), providing the first confinement barrier.As a result of reviews and the latest physics analyses, design requirements have been updated (e.g. ELM/VS coils) and a few design changes have to be implemented. This paper covers the updates of the VV vertical and horizontal EM load conditions during asymmetric VDEs, the design analysis of the ELM/VS coils and their interfaces to the VV, the blanket manifold design and the preparation of the technical specification in preparation for the procurement arrangement to be signed.