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Noise-controlled pattern formation and threshold shift for electroconvection in the conduction and dielectric regimes

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Physical Review E 2009年第6期80卷 066304-066304页

作者： Jong-Hoon Huh Akiyuki Kuribayashi Shoichi Kai Department of Mechanical Information Science and Technology Faculty of Computer Science and Systems Engineering Kyushu Institute of Technology Fukuoka 820-8502 Japan Department of Applied Quantum Physics and Nuclear Engineering Faculty of Engineering Kyushu University Fukuoka 812–8581 Japan

We report noise-controlled electrohydrodynamic pattern formations and threshold shifts in nematic liquid crystals. In the electrohydrodynamic system superposed with noise, experimental results obtained in the dielectric regime are compared to those in the conventional conduction regime. The noise intensity dependences of thresholds and pattern evolution processes are remarkably different for each regime. The pattern formation mechanisms in the presence of noise for both regimes are discussed based on the results. Moreover, it is found that the thresholds and characteristic wavelengths of dissipative structures can be effectively controlled by external multiplicative noises with appropriate intensity and correlation times.

关键词： Electrohydrodynamics

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Design and performance of the ABCN-25 readout chip for ATLAS Inner Detector Upgrade

Design and performance of the ABCN-25 readout chip for ATLAS...

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IEEE Symposium on Nuclear science (NSS/MIC)

作者： Wladyslaw Dabrowski Francis Anghinolfi Nandor Dressnandt Michal Dwuznik Sergio Gonzalez-Sevilla Jan Kaplon Daniel La Marra Mitchell F. Newcomer Sebastien Pernecker Karolina Poltorak Krzysztof Swientek Faculty of Physics and Applied Computer Science AGH University of Science and Technology Krakow Poland CERN Geneva Switzerland Physics Department University of Pennsylvania USA Geneva University Switzerland

We present the design and performance of the ABCN-25 readout chip implemented in 0.25 ¿m CMOS technology. The front-end design has been optimized for the short, 2.5 cm, silicon strips foreseen in the upgrade of the ATLAS Inner Detector. The core of the readout architecture includes binary front-end, two levels of data buffering, data compression and data serializing circuitry, and is similar to the architecture of the ABCD3T chip used in the present ATLAS SCT detector. In order to ensure required radiation hardness the hardening by layout technique has been used and SEU detection and correction circuitry have been added. The design includes on-chip power management circuitry comprising two types of shunt regulators and a serial regulator. This circuitry makes the ABCN-25 chip compatible with recent developments in the area of power distribution systems for the inner trackers in the SuperLHC environment and in particular with serial powering of the detector modules. The chip has been fabricated in 0.25 ¿m CMOS technology and full functionality has been obtained. The critical design aspects and performance of the analog and digital circuits will be presented and discussed.

关键词： Detectors CMOS technology Circuits Regulators Design optimization Silicon Strips computer buffers Data compression Radiation hardening

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Modeling buildings for mobile robots

Modeling buildings for mobile robots

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2009 ASCE International Workshop on Computing in Civil Engineering

作者： Borkowski, A. Grabska, E. Palacz, W. Department of Intelligent Systems Institute of Fundamental Technological Research Polish Academy of Sciences 21 Swietokrzyska Str. PL-00-049 Warsaw Poland Department of Computer Design and Graphics Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University 4 Reymonta Str. PL-30-059 Krakow Poland

ISBN: (纸本)9780784410523

In the near future mobile robots accomplishing such tasks as delivery of goods, assistance for handicapped people and surveillance will become increasingly available. The aim of this paper is to show the disparity that exists at present in modeling buildings for the purposes of two domains: Architecture, Engineering & Construction (AEC) and Mobile Robotics (MR). Digital product and process models developed in the AEC-domain give the user a comprehensive insight into the components and functions of the building but they neglect the needs of mobile robot operating autonomously inside the building. On the other hand, researchers in the MR-domain seem to be unaware of the results achieved in the AEC area. During the last decades the main effort in MR was devoted to the autonomous navigation. This resulted in efficient and robust procedures of acquiring floor maps from sensor readings. Further progress requires the robot to understand semantics of the surrounding world. Based on our previous research in the graph-oriented support of the AEC-design, we propose a digital model of the building that will enable the robot to recognize the functionality of particular spaces, to transform CAD-based floor plans into graphs reflecting topology and function of the building, to plan the execution of tasks posed by the human operator and to navigate inside the building. © 2009 ASCE.

关键词： Mobile robots

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A view-based approach for recognition of Bengali printed characters

A view-based approach for recognition of Bengali printed cha...

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World Congress on Nature & Biologically Inspired Computing (NaBIC)

作者： S. H Shaikh N. Chaki M. Tabedzki K. Saeed A. K. Choudhury School of Information Technology University of Calcutta India Faculty of Computer Science Bialystok Technical University Poland Faculty of Physics and Applied Computer Science AGH University of Science and Technology Cracow Poland

This paper presents a method for recognizing Bengali printed characters by using view-based and layer-based approaches. Two different view-based approaches, the top-bottom and the left-right have been used. The layer-based approach is also considered here. No thinning or segmentation is required. The individual character is taken as a whole image. The characteristic points are extracted from the views after some preprocessing. These points are then used to form a feature vector which represents the given character. These feature vectors are classified with the aid of dynamic time warping distance, k-NN and ensemble of classifiers. The concept can also be extended for Bengali word recognition.

关键词： Character recognition Image analysis Pixel computer science Data acquisition Character generation Performance analysis Information technology physics Image segmentation

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Direct Evidence of a Nonorthogonal Magnetization Configuration in Single Crystalline Fe1−xCox/Rh/Fe/Rh(001) System

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Physical Review Letters 2009年第14期103卷 147203-147203页

作者： F. Yildiz M. Przybylski J. Kirschner Max-Planck-Institut für Mikrostrukturphysik Weinberg 2 06120 Halle Germany Faculty of Physics and Applied Computer Science AGH University of Science and Technology Mickiewicza 30 30-059 Kraków Poland

Tetragonal distortion in Fe1−xCox alloy films grown epitaxially on Rh(001) substrates results in a strong perpendicular magnetic anisotropy. Since the perpendicular magnetic anisotropy varies with the Fe1−xCox film composition, one can grow multilayer structures with ferromagnetic films sequentially showing either an in-plane (e.g., Fe) or out-of-plane (e.g., Fe0.5Co0.5) easy-magnetization axis. The Rh spacers mediate an interlayer coupling which couples the magnetizations either ferromagnetically or antiferromagnetically, depending on the spacer thickness. When the anisotropy energy is compatible to the coupling, it produces nonorthogonal magnetization configurations which vary under a small change of the external magnetic field.

关键词： Magnetization

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Pd Atomic Chain Formation as a Result of Submonolayer Deposition of 3d Metals on Pd(110)

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Physical Review Letters 2009年第22期103卷 225504-225504页

作者： D. H. Wei C. L. Gao Kh. Zakeri M. Przybylski Max-Planck-Institut für Mikrostrukturphysik Weinberg 2 06120 Halle Germany and Faculty of Physics and Applied Computer Science AGH University of Science and Technology Mickiewicza 30 30-059 Kraków Poland

Submonolayer deposition of 3d transition metals such as Cr, Mn, Fe, Co, and Ni on Pd(110) at room temperature causes the formation of monoatomic chains of Pd as identified with scanning tunneling microscopy and spectroscopy. In agreement with recent theoretical predictions [Phys. Rev. B 79, 155410 (2009)], the substitution of Pd substrate atoms with the deposited atoms of 3d metals is found to be responsible for the formation of Pd atomic chains. This finding clarifies the long-debated issue about the chemical composition of the atomic chains grown on Pd(110) and points out the intriguing processes in the formation of self-assembled and self-organized nanostructures.

关键词： Scanning tunneling microscopy

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Low noise, low power front end electronics for pixelized TFA sensors

Low noise, low power front end electronics for pixelized TFA...

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Topical Workshop on Electronics for Particle physics, TWEPP 2009

作者： Poltorak, K. Ballif, C. Dabrowski, W. Despeisse, M. Jarron, P. Kaplon, J. Wyrsch, N. CERN 1211 Geneva 23 Switzerland Photovoltaics and Thin Film Electronics Laboratory EPFL-STI-IMT-NE PV-LAB Rue Breguet 2 CH-2000 Switzerland AGH - University of Science and Technology Faculty of Physics and Applied Computer Science Al. Mickiewicza 30 30-059 Cracow Poland

ISBN: (纸本)9789290833352

Thin Film on ASIC (TFA) technology combines advantages of two commonly used pixel imaging detectors, namely, Monolithic Active Pixels (MAPs) and Hybrid Pixel detectors. Thanks to direct deposition of a hydrogenated amorphous silicon (a-Si:H) sensor film on top of the readout ASIC, TFA shows the similarity to MAP imagers, allowing, however, more sophisticated front-end circuitry to extract the signals, like in case of Hybrid Pixel technology. In this paper we present preliminary experimental results of TFA structures, obtained with 10 · thick hydrogenated amorphous silicon sensors, deposited directly on top of integrated circuit optimized for tracking applications at linear collider experiments. The signal charges delivered by such a-Si:H n-i-p diode are small;about 37 e-/·· for minimum ionizing particles, therefore a low noise, high gain and very low power of the front- end are of primary importance. The developed demonstrator chip, designed in 250 ·· CMOS technology, comprises an array of 64 by 64 pixels laid out in 40 ·· by 40 ·· pitch.

关键词： Pixels

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Magnetic-Field Asymmetry of Electron Wave Packet Transmission in Bent Channels Capacitively Coupled to a Metal Gate

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Physical Review Letters 2009年第6期102卷 066807-066807页

作者： R. Kalina B. Szafran S. Bednarek F. M. Peeters Faculty of Physics and Applied Computer Science AGH University of Science and Technology al. Mickiewicza 30 30-059 Kraków Poland Departement Fysica Universiteit Antwerpen Groenenborgerlaan 171 B-2020 Antwerpen Belgium

We study the electron wave packet moving through a bent channel. We demonstrate that the packet transmission probability becomes an asymmetric function of the magnetic field when the electron packet is capacitively coupled to a metal plate. The coupling occurs through a nonlinear potential which translates a different kinetics of the transport for opposite magnetic-field orientations into a different potential felt by the scattered electron.

关键词： Magnetic fields

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Ballistic versus electronic processes in ion-induced nanostructuring of ionic surfaces

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Physical Review B 2009年第23期79卷 235432-235432页

作者： F. Krok S. R. Saeed Z. Postawa M. Szymonski Research Center for Nanometer-Scale Science and Advanced Materials (NANOSAM) Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University ul. Reymonta 4 30-059 Krakow Poland

High-resolution noncontact atomic force microscopy in UHV has been used for characterization of KBr(001) surface morphology development due to an oblique incidence of low-energy ion beams (4 keV He+ and Ar+ at 75°). We have found several features of the process directly related to the ionic nature of halide surfaces, such as formation of two-dimensional (2D) pits and rectangular 2D epitaxial adislands on the initially atomically flat terraces. At low bombardment fluence the evolution of the 2D pits proceeds along main surface crystallographic directions. Such behavior is typical for the electron stimulated desorption (ESD) process, well-known from electron and photon irradiation experiments. No epitaxial adislands formation by ESD or by ion impact has been reported so far. For prolonged ion bombardment surface topography transforms into a regular network of grooves and rims (a ripple structure) oriented parallel to the incident beam. Such a structure has been observed for many other materials (metals and semiconductors), with a major distinction, however, that for KBr the ripples are composed of small nanosize crystallites with a persistent long-range order of the (001) surface. We have demonstrated that the fluence threshold for a transition from a random network of 2D pits and adislands into a well-oriented crystalline nanoripple structure is directly related to the balance between the electronic and ballistic stopping of the impinging ions. The theoretical interpretation of our observations is based on an atomistic approach to the ion-solid interaction and supplementary molecular-dynamics computer simulations of a single-ion impact on flat and atomic step covered surfaces. In particular, the computer simulations demonstrate that the sputtering yield for ions impinging against the ascending step edges on the irradiated surface are much greater than the ones obtained for the descending step bombardment.

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Influence of dispersed core-shell nano-sized particles on P3OT based photovoltaic device

Influence of dispersed core-shell nano-sized particles on P3...

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ICTON Mediterranean Winter Conference

作者： Jacek Niziol Ewa Gondek Andrzej Danel Jerzy Sanetra Faculty of Physics and Applied Computer Science AGH University of Science and Technology Krakow Poland Institute of Physics Cracow University of Technology Krakow Poland Department of Chemistry Agricultural University Krakow Poland

This work reports application of core-shell nanoparticles in photovoltaic cells. These nanoparticles were fabricated form silicon carbide core covered with conductive form of polyaniline. The nanoparticles were dispersed in the active layer of the cell. It was found that this modification raised quantum efficiency of the photovoltaic cell by factor of three in comparison to a test cell without nanoparticles.

关键词： Nanoscale devices Photovoltaic systems Solar power generation Polymers Electrodes Photovoltaic cells Excitons Electrons Nanoparticles Indium tin oxide

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