Search

Start Over Creator Matoušek, Václav

2. A new approach to signature verigication: digital data acquisition pen

Creator:
Rohlík, Ondřej, Mautner, Pavel, Matoušek, Václav, Kempf, Jürgen, and Weinzierl, Kurt
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
signature verification, person identification, character recognition, OCR, and HCI
Language:
English
Description:
This paper preseiits our experience with a completely new approach to handwritten text recognitiori. A brief description of a new type of input devices is followed by a more detailed explanation of recognition methods used. The results achieved are discussed and ideas ror further research are suggested.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

3. Automated reverse Engineering of CAN protocols

Creator:
Weiß, Nils, Pozzobon, Enrico, Mottok, Jürgen, and Matoušek, Václav
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
controller area networks, statistical analysis, and neural networks
Language:
English
Description:
Car manufacturers define proprietary protocols to be used inside their vehicular networks, which are kept an industrial secret, therefore impeding independent researchers from extracting information from these networks. This article describes a statistical and a neural network approach that allows reverse engineering proprietary controller area network (CAN)-protocols assuming they were designed using the data base CAN (DBC) file format. The proposed algorithms are tested with CAN traces taken from a real car. We show that our approaches can correctly reverse engineer CAN messages in an automated manner.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4. Coherence of EEG Signals and Biometric Signals of Handwriting under Influence of Nicotine, Alcohol, and Light Drugs

Creator:
Maršálek, Tomáš, Matoušek, Václav, Mautner, Pavel, Merta, Michal, and Mouček, Roman
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
computerized EEG signal evaluation, biometric signals, and signal coherence
Language:
English
Description:
Subject matter of investigations being carried out at the University of West Bohemia in Pilsen and described in this chapter is the objective evaluation of possible coherence of EEG signals and signals of handwriting generated by special developed BiSP pen. The influence of nicotine, alcohol and light drugs on the vigility and activity of human operators was investigated and evaluated; the results of the experiments being realized during the last five months are summarized in the last paragraph.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

5. Collisional transport model for intense bed load

Creator:
Matoušek, Václav and Zrostlík, Štěpán
Format:
počítač and online zdroj
Type:
model:article and TEXT
Subject:
granular flow, sheet flow, sediment transport, grain collision, tilting flume experiment, and kinetic theory
Language:
Slovak
Description:
In an open channel with a mobile bed, intense transport of bed load is associated with high-concentrated sediment-laden flow over a plane surface of the eroded bed due to high bed shear. Typically, the flow exhibits a layered internal structure in which virtually all sediment grains are transported through a collisional layer above the bed. Our investigation focuses on steady uniform turbulent open-channel flow with a developed collisional transport layer and combines modelling and experiment to relate integral quantities, as the discharge of solids, discharge of mixture, and flow depth with the longitudinal slope of the bed and the internal structure of the flow above the bed. A transport model is presented which considers flow with the internal structure described by linear vertical distributions of granular velocity and concentration across the collisional layer. The model employs constitutive relations based on the classical kinetic theory of granular flows selected by our previous experimental testing as appropriate for the flow and transport conditions under consideration. For given slope and depth of the flow, the model predicts the total discharge and the discharge of sediment. The model also predicts the layered structure of the flow, giving the thickness of the dense layer, collisional layer, and water layer. Model predictions are compared with results of intense bed-load experiment carried out for lightweight sediment in our laboratory tilting flume.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

6. Distribution of medium-sand particles in flow above erodible bed at high shear stress

Creator:
Matoušek, Václav
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
sheet flow, particle dispersion, suspension, concentration profile, bed shear stress, smykové proudění, disperze částic, suspenze, koncentrační profil, and smykové napětí ve dně
Language:
Slovak
Description:
If the Shields number of a flow above an erodible bed is higher than one, then the current exerts so high shear stress at the top of a granular bed that the upper part of the bed is eroded and the top of the non-eroded rest of the bed is flat (no bed forms occur). This flow regime is typical for flows over a stationary bed in pipes but it can occur also in open-channel flows, particularly under flood conditions when both the depth and velocity of the flow are high. The current picks up particles from the eroded part of the bed and transports them within the flow. The total load of transported particles is composed of particles transported either as the contact load or as the suspended load, depending on the dispersive mechanism that keeps the particles inside the flow. Solids distribution (i.e. the shape of the concentration profile) of the transported particles across the flow helps to identify an acting dispersive mechanism and hence a mechanism through which the transported particles contribute to flow friction. The paper analyzes the concentration-profile measurements in a medium-sand-slurry current above an erodible stationary bed in a 150-mm pipe. The experiments revealed interesting effects of high shear stress on the shapes of concentration profiles across the flow above the bed. The analysis suggests that carrier turbulence is a prevailing dispersion mechanism within the upper part of the discharge area above the bed for flow conditions characterized by values of the ratio u*b/vt higher than say 4.5. It seems that the shearing action as an exclusive particle dispersion mechanism is confined to the region not far above the top of the bed. Apparently, the high shear stress at the top of the stationary bed is capable of producing turbulent suspension that transports a considerable amount of medium-sand particles (average delivered volumetric concentrations of transported particles up to 0.26) through the 150-mm pipe. and Při proudění vody nad pohyblivým dnem za podmínek vysokého smykového napětí na povrchu dna (Shieldsovo číslo větší než 1) je horní vrstva dna erodována proudem vody a na povrchu neerodované části dna nevznikají dnové útvary. Takové proudění se vyskytuje například v potrubí dopravujícím směs nad sedlinou na dně potrubí, ale může se vyskytnout i v otevřeném korytě, zvláště za povodňové situace, kdy jsou pro proudění typické velká rychlost a velká hloubka vody. Proud unáší částice z erodované vrstvy dna. Mechanismy, které mohou udržovat částice v proudu, jsou v principu dva: turbulentní suspenze a mezičásticový kontakt. Každý z těchto mechanismů způsobuje jiné rozdělení částic, tj. jiný koncentrační profil, po svislici proudu. Měřením koncentračních profilů by tedy mělo být možné odhadnout, jaký mechanismus převažuje v proudění za určitých sledovaných podmínek. Příspěvek analyzuje koncentrační profily měřené v potrubí průměru 150 mm při proudění vodní směsi střednězrnného písku nad pískovou sedlinou. Analýza výsledků měření ukázala, že turbulence v proudu vody je převažujícím mechanismem podpory částic přinejmenším v horní polovině výšky průtočné části potrubí při podmínkách charakterizovaných hodnotou poměru třecí rychlosti ve dně a usazovací rychlosti unášené částice (u*b/vt) větší než přibližně 4,5. Na rozdíl od dřívějších závěrů v literatuře se zdá, že mezičásticové kolize se jako výhradní mechanismus disperze částic uplatňují jen v poměrně omezené oblasti proudu nad povrchem dna. Vysoké smykové napětí ve dně tak přispívá nejen ke vzniku mezičásticových kolizí, ale i k turbulentní podpoře částic. Turbulentní podpora umožňuje dosažení vysokých hodnot (až do 0,26) dopravní koncentrace částic střednězrnného písku ve směsi proudící potrubím průměru 150 mm.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

8. Erosion of plane bed by sand slurry current in pipe

Creator:
Matoušek, Václav
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
pick-up, hindered erosion, suspension flow, bed friction, sběr částic erozí (pick-up), rušená eroze, proud suspenze, and dnové tření
Language:
Slovak
Description:
If a sand slurry current flows over a plane bed the thickness of the bed remains constant providing that equilibrium is established between the vertical fluxes that govern the exchange of particles between the slurry current and the sand bed. These solids fluxes are the settling flux and the erosion (pick-up) flux through the top of the bed. In the literature, relations to quantify the erosion flux from a sand bed consider the water current above an erodible bed. The effect of the presence of solid particles in the current is not taken into account. However, it has been observed that the presence of solid particles tends to suppress pick-up. This phenomenon is called hindered erosion. At present, the knowledge of the process of hindered pick-up is very limited although it is suspected that the hindered pick-up plays an important role in many practical situations. The paper discusses the results of the plane-bed test recently carried out in a 150-mm pipe of the Laboratory of Dredging Engineering of Delft University of Technology. Measurements of the thickness of the bed, the concentration profiles in the pipe cross section, the mean velocity, and the pressure drop allowed us to evaluate the conditions governing the vertical exchange of solids at the top of the stationary bed for currents of different solids concentrations. and Při proudění písčité hydrosměsi nad nepohyblivým ložem v tlakovém potrubí dochází k výměně pískových částic mezi proudem a ložem. Tloušťka lože zůstává neměnná, pokud při výměně existuje rovnováha mezi vertikálním proudem částic ze suspenze do sedliny (sedimentační proud) a opačně (erozní proud). V literatuře existující modely pro erozní proud jsou navrženy pro situace, kdy eroze je způsobena prouděním vody nad ložem, vliv přítomnosti unášených částic v proudu tedy není uvažován. V minulosti však již bylo pozorováno, že přítomnost suspendovaných částic může vést k zmenšení schopnosti proudu sbírat částice ze dna. Tento jev se nazývá rušená eroze. V současnosti jsou ještě poznatky o rušené erozi velmi omezené, přestože se dá předpokládat, že rušená eroze hraje významnou roli v mnoha situacích vyskytujících se v praxi. Tento příspěvek pojednává o výsledcích nedávných měření proudění písčité směsi nad nepohyblivým ložem v kruhovém potrubí průměru 150 mm v Laboratoři Dredging Engineering Technické univerzity v Delftu. Měřeny byly tloušťky lože, koncentrační profily nad ložem, střední rychlosti a tlakové ztráty v potrubí. Tato měření umožnila vyhodnocení vertikálního erozního proudu částic z povrchu lože pro různé koncentrace unášených částic ve směsi proudící nad ložem a vlivu koncentrací na erozi.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

10. Experimental investigation of internal structure of open-channel flow with intense transport of sediment

Creator:
Matoušek, Václav, Bareš, Vojtěch, Krupička, Jan, Picek, Tomáš, and Zrostlík, Štěpán
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
acoustic anemometry, plane bed, solid-liquid flow, and tilting flume experiment
Language:
Slovak
Description:
Gravity-driven open-channel flows carrying coarse sediment over an erodible granular deposit are studied. Results of laboratory experiments with artificial sediments in a rectangular tilting flume are described and analyzed. Besides integral quantities such as flow rate of mixture, transport concentration of sediment and hydraulic gradient, the experiments include measurements of the one-dimensional velocity distribution across the flow. A vertical profile of the longitudinal component of local velocity is measured across the vertical axis of symmetry of a flume cross section using three independent measuring methods. Due to strong flow stratification, the velocity profile covers regions of very different local concentrations of sediment from virtually zero concentration to the maximum concentration of bed packing. The layered character of the flow results in a velocity distribution which tends to be different in the transport layer above the bed and in the sediment-free region between the top of the transport layer and the water surface. Velocity profiles and integral flow quantities are analyzed with the aim of evaluating the layered structure of the flow and identifying interfaces in the flow with a developed transport layer above the upper plane bed.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public