Showing papers by "Brno University of Technology published in 2003"

Virtual reconfigurable circuits for real-world applications of evolvable hardware

Abstract: The paper introduces a new method for the design of real-world applications of evolvable hardware using common FPGAs (Field Programmable Gate Arrays). In order to avoid "reconfiguration problems" of current FPGAs a new virtual reconfigurable circuit, whose granularity and configuration schema exactly fit to requirements of a given application, is designed on the top of an ordinary FPGA. As an example, a virtual reconfigurable circuit is constructed to speed up the software model, which was utilized for the evolutionary design of image operators.

Ab initio calculations of elastic and magnetic properties of Fe, Co, Ni, and Cr crystals under isotropic deformation

Abstract: Ab initio electronic structure calculations of the ideal strength of Fe, Co, Ni, and Cr under isotropic tension were performed using the linear muffin-tin orbital method in the atomic sphere approximation. Magnetic ordering was taken into account by means of a spin-polarized calculation. Two approximations for the exchange-correlation term were employed: namely, the local (spin) density approximation and the generalized gradient approximation. Computed values of equilibrium lattice parameters, bulk moduli, and magnetic moments were compared with available experimental data. The stability of the ground-state structure in the tensile region was assessed via comparison of its total energy and enthalpy with those of some other structures. No instabilities were found before reaching the inflection point on the total energy versus volume curve and the stress related to this point was therefore considered to be the ideal strength.

Measuring teamwork culture: the use of a modified EFQM model

Abstract: This paper discusses teamwork, development of a team‐based organisation and performance measurement issues. This discussion leads to the formulation of a methodology to measure the organisational journey towards a team‐based organisational paradigm. The TEaM model, a model based on the EFQM excellence model, is suggested as a self‐assessment tool for the measurement of teamwork culture in organisations. Consequently, a five step‐approach aimed at successful acquisition of the proposed model is recommended. The authors demonstrate the usefulness of TEaM, not only in the improvement of teamwork culture in organisations, but also in reducing the resistance to change efforts while supporting the knowledge exchange through continuous self‐assessment of teams.

Integrated smart sensor networking framework for sensor-based appliances

Abstract: This paper presents an integrated, sensor networking framework stemming from the IEEE 1451 smart transducer interface standard. This object-based networking model is complemented by the Virtual Interface Architecture (VIA), a Compaq-Intel-Microsoft approach to Internet messaging, and by the Internet Protocol (IP) multicast communication, mediating efficient and unified access from Internet to smart sensors. An application of networked sensors that offers a reusable design pattern for a class of sensor-based appliances is analyzed. The kernel of the paper focuses utilization of this framework for a computer-based pressure measurement systems developing environment as a real-world project while stressing smart pressure sensor and Internet connectivity architectures.

Towards evolvable IP cores for FPGAs

Abstract: The paper deals with a new approach to the design of adaptive hardware using common field programmable gate arrays (FPGA). The ultimate aim is to develop evolvable IP (intellectual property) cores. The cores should be reused in the same way as ordinary IP cores are reused. In contrast to the conventional cores, the evolvable cores are able to perform autonomous evolution of their internal circuits. The cores should be available in the form of HDL source code, i.e. they should be synthesizable into any reconfigurable device of a sufficient capacity. The approach is based on implementation of a virtual reconfigurable circuit and a genetic unit in an ordinary FPGA. In the presented case study an adaptive image filter is designed, implemented and synthesized. The proposed idea of evolvable IP core could open the way towards defining a business model for evolvable hardware.

Real-Time Systems: Reflections on higher education in the Czech Republic, Hungary, Poland and Slovenia

Abstract: Real-time systems (An ICT definition) In real-time multiprocessing there is the extra requirement that the system complete its response to any input within a certain critical time. This poses additional problems, particularly in situations where the system is heavily loaded and is subject to many simultaneous demands. Real-time systems are always dedicated. Most systems are not real-time.

Application of inverse kinematics for skeleton manipulation in real-time

Abstract: Usual way of character's animation is the use of motion captured data. Acquired bones' orientations are blended together according to user input in real-time. Although this massively used method gives a nice results, practical experience show how important is to have a system for interactive direct manipulation of character's skeleton in order to satisfy various tasks in Cartesian space. For this purpose, various methods for solving inverse kinematics problem are used. This paper presents three of such methods: Algebraical method based on limbs positioning; iterative optimization method based on Jacobian pseudo-inversion; and heuristic CCD iterative method. The paper describes them all in detail and discusses practical scope of their use in real-time applications.

High-resolution imaging of a soft-X-ray laser beam by color centers excitation in lithium fluoride crystals

Abstract: Stable color center production in lithium fluoride crystals has been applied to single-shot high-spatial-resolution imaging of a 2 ns long, 46.9 nm capillary discharge soft-X-ray laser pulse. Images of the unfocused beam and of the beam focused by a multi-layer mirror were recorded. The LiF crystal sensitivity was sufficient to impress high-contrast photo-luminescent patterns with single-pulse irradiation on an area up to 40 mm2. Interference fringes due to the soft-X-ray laser coherence were observed. The results demonstrate the potential of LiF crystals and films as a sub-micrometer resolution two-dimensional imaging tool for single-shot soft-X-ray laser applications.

Fractal–Cantorian geometry, Hausdorff dimension and the fundamental laws of physics

Abstract: Fractal geometry is widely used nowadays in many scientific areas. The authors are trying to link its uses to a description of fractal basis of fundamental physical laws. Fractals seem to be very powerful in describing natural objects on all scales. Fractal dimension and fractal measure, are crucial parameters for such description. They imply that there are no different laws, which act on different scales but there is a small set of universal properties, which act in different dimensional spaces as in El Naschie’s Cantorian e(∞) theory. The article describes the relation between fractal–Cantorian geometry and fundamental physical laws. It shows dependence between fractal describing parameters and quantities, which characterize properties of real world.

Filters with Multi-Loop Feedback Structure in Current Mode

Abstract: Universal multifunctional (low-pass, high-pass, band-pass, band-reject and all-pass) n-order active RC filters in current mode are presented in this paper. The filters are based on several multi-loop feedback and statevariable structures. Their modification and implementation using multi-output transconductors (OTA) and current followers are given.

Design of multithreaded estimation of distribution algorithms

Abstract: Estimation of Distribution Algorithms (EDAs) use a probabilistic model of promising solutions found so far to obtain new candidate solutions of an optimization problem. This paper focuses on the design of parallel EDAs. More specifically, the paper describes a method for parallel construction of Bayesian networks with local structures in form of decision trees in the Mixed Bayesian Optimization Algorithm. The proposed Multithreaded Mixed Bayesian Optimization Algorithm (MMBOA) is intended for implementation on a cluster of workstations that communicate by Message Passing Interface (MPI). Communication latencies between workstations are eliminated by multithreaded processing, so in each workstation the high-priority model-building thread, which is communication demanding, can be overlapped by low-priority model sampling thread when necessary. High performance of MMBOA is verified via simulation in TRANSIM tool.

XPS study of siloxane plasma polymer films

Abstract: Plasma polymer films were deposited from hexamethyldisiloxane (HMDSO), dichloro(methyl)phenylsilane (DCMPS) and vinyltriethoxysilane (VTEO) on polished silicon wafers using a RF helical coupling deposition system. The composition of elements in the surface region (top 6–8 nm) of the deposited films was studied by X-ray-induced photoelectron spectroscopy (XPS) on an ADES 400 VG Scientific photoelectron spectrometer using MgK α (1253.6 eV) or AlK α (1486.6 eV) photon beams at the normal emission angle. Aging effects of plasma-polymerized (PP) HMDSO and DCMPS films stored under standard laboratory conditions were investigated by employing XPS. Post-deposition contamination and oxidation of pp-DCMPS and pp-HMDSO film was carefully observed. An increase in oxygen atoms on the film surface over time is accompanied by changes in bulk atomic concentrations. Sequential sputtering with an Ar ion-beam, together with XPS analysis, was used to measure concentration depth profiles in pp-HMDSO and pp-DCMPS films.

Behaviour of an optically trapped probe approaching a dielectric interface

Abstract: The way in which reflection of the trapping beam from a dielectric interface influences the distance of the trapped sphere from the beam waist is studied theoretically and experimentally. The reflected wave interferes with the incident wave and they create a standing-wave component in the total axial intensity distribution. This component then modulates the trapping potential and creates several possible equilibrium positions for the trapped sphere. When the beam waist approaches the surface, the potential profile changes, which consequently causes jumps of the trapped probe from its current location to a deeper potential well. We suggested theoretically and proved experimentally that the magnitude of these unwanted jumps between the neighbouring equilibrium positions can be decreased by a suitable size of the sphere.

Easily testable image operators: the class of circuits where evolution beats engineers

Abstract: The paper deals with a class of image filters in which the evolutionary approach consistently produces excellent and innovative results. Furthermore, a method is proposed that leads to the automatic design of easily testable circuits. In particular we evolved "salt and pepper" noise filters, random shot noise filters, Gaussian noise filters, uniform random noise filters, and edge detectors.

Electro-optical recording system for myocardial ischemia studies in animal experiments

Abstract: Myocardial ischemia is the most common cause of death in the developed countries. The most severe manifestation is sudden death due to electrical instability, terminating in ventricular fibrillation or heart arrest. This study is based on experiments in which electrograms and monophasic action potentials are recorded from isolated guinea pig hearts perfused according to Langendorff during various phases of acute ischemia and reperfusion. The data are then processed by a wavelet transform in order to obtain complex-valued time-frequency patterns.

Wireless communication in automation

Abstract: The paper shows the challenges associated with attempts to utilize Bluetooth communication interface for automation purposes like control and data acquisition The paper describes major challenges, selected approach, first tests, first experiences with Bluetooth on Linux and first prototypes of embedded devices used for testing Moreover the paper discusses some specific challenges associated with utilization of wireless communication techniques (focused to Bluetooth) in automation Finally the paper presents ideas (formal methods) that could be used to analyze, and improve reliability of such system, and approach (time triggered approach with clock synchronization) that could be used to improve the deterministicity of wireless communication channels

Simultaneously One-Turn Two-Pushdown Automata

Abstract: Consider two consecutive moves, $m_{1}$ and $m_{2}$ , made by a two-pushdown automaton, M , whose pushdowns are denoted by $\pi_{1}$ and $\pi_{2}$ . If during $m_{1}$ M does not shorten $\pi_{i}$ , for some $i = 1, 2$ , while during $m_{2}$ it shortens $\pi_{i}$ , then M makes a turn in $\pi_{i}$ during $m_{2}$ . If M makes a turn in both $\pi_{1}$ and $\pi_{2}$ during $m_{2}$ , this turn is simultaneous . A two-pushdown automaton is one-turn if it makes no more than one turn in either of its pushdowns during any computation. A two-pushdown automaton is simultaneously one-turn if it makes either no turn or one simultaneous turn in its pushdowns during any computation. This paper demonstrates that every recursively enumerable language is accepted by a simultaneously one-turn two-pushdown automaton. Consequently, every recursively enumerable language is accepted by a one-turn two-pushdown automaton.

Conductivity mechanisms and breakdown characteristics of niobium oxide capacitors

Abstract: Niobium Oxide capacitor, has already found its place in the market as a cost effective and reliable non-burning component. The study of conductivity mechanisms has been done to prove its excellent stability, reliability and non-burning performance. Set of electrical measurements as VA characteristics in forward and reverse mode, frequency characteristics of capacitance, temperature or time dependence of basic parameters together with measurements of basic physical parameters enabled to propose the theoretical model of NbO – Nb2O5 – MnO2 system. NbO Capacitor shows identical conductivity mechanism as tantalum capacitor, but furthermore a unique mechanism appears after dielectric breakdown. It causes a high resistance failure mode of NbO capacitor and limits the current bellow the capacitor’s thermal runaway point, which prevents capacitor’s burning, whereas filtering characteristics remain unchanged.

Descriptional Complexity Of Generalized Forbidding Grammars

Abstract: This paper discusses the descriptional complexity of generalized forbidding grammars. It proves that every recursively enumerable language is generated by a generalized forbidding grammar containing no more than thirteen forbidding productions and no more than fifteen nonterminals.

Highly coherent tunable semiconductor lasers in metrology of length

Abstract: Laser diodes became the most widespread lasers and now are available in a broad spectrum of wavelengths ranging from infrared to the visible region The low power ones mainly those with the quantum well structure and gain or index guided configuration perform a narrow linewidth and soon became a favourite tool for interferometry and spectroscopy The need for continuous tuning range led to the development Extended Cavity Laser systems (ECL) and Vertical Cavity Surface Emitting Lasers (VCSEL) Both systems seem to be promising laser sources for design of optical frequency standards or interferometric distance measurement devices We present design of these laser systems and their applications in metrology of length

The hybrid mobile robot

Abstract: A hybrid mobile robot, as its name suggests, consists of a number of different types of locomotion mechanisms. In most cases, two types of locomotion devices are combined, for example wheel-leg, track-wheel, etc. On an even and solid surface the robot moves by means of a mechanism that permits high speed motion (such as a wheel undercarriage). In an uneven or ragged terrain the robot is capable of scaling obstacles using mechanisms that make for easier movement in such an environment (e.g. a track undercarriage, walking mechanism). The benefits of a combined kinematic structure include a relatively high speed of motion and a good manoeuvrability in an uneven terrain. This contribution deals with the up-to-date developments in the field of hybrid robots (HR) and describes possible alternative designs of mobile robot constructions.

Particle rendering pipeline

Abstract: This paper presents a particle rasterizing pipeline that is intended as a part of a particle system rendering engine. The purpose of the rasterizing pipeline is to convert the particles, which are geometrically just a projection of circles onto a plane, into pixels of a raster image. While the conversion is relatively simple, the required speed is very high as the particle systems typically contain very large numbers of particles - at least hundreds of thousands - and the general goal is to handle the rendering in real time. The presented solution does have the capability of achieving such high speeds.

Sub-milliradiant divergence soft-X-ray laser by active plasma waveguiding in z-pinch capillary discharge

Abstract: We report the observation of the sub-milliradiant divergence operation of a capillary discharge soft-X-ray laser, that indicates that X-ray radiation has been amplified in a refraction-guiding plasma active medium. The lasing is produced on the 46.9 nm transition of the Ne-like Ar. The 0.7 mrad divergence, axially peaked-profile beam is obtained in the single-pass amplification regime. The comparison of the recorded laser beam profiles with the results of our computer simulations shows that the capillary discharge z-pinch forms an active plasma wave guide, which has the electron density profile with depression on its axis. The waveguiding of X-ray radiation and its amplification is demonstrated over a 30 cm long plasma column, where the laser operates in a saturated regime with energy of ~ 50 μJ.

Imaging of the expansion of femtosecond-laser-produced silicon plasma atoms by off-resonant planar laser-induced fluorescence

Abstract: Planar laser-induced fluorescence measurements were used to investigate the expansion dynamics of a femtosecond laser-induced plasma. Temporally and spatially resolved measurements were performed to monitor the atoms that were ablated from a silicon target. A dye laser (λ = 288.16 nm) was used to excite fluorescence signals. The radiation of an off-resonant transition (Si 390.55 nm) was observed at different distances from the target surface. This allowed easy detection of the ablated Si atoms without problems caused by scattered laser light. Abel inversion was applied to obtain the radial distribution of the Si atoms. The atom distribution in the plasma shows some peculiarities, depending on the crater depth.