Number of found documents: 315
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Study on pervious recycled aggregate fiber-reinforced concrete for airfield pavement
Novák J.; Chylík R.; Trtík T.; Kohoutková A.
2020 - English
For the last several years, the attention has been devoted to the development of ecofriendly construction materials with the aim to reduce the environmental impact of construction. The integral part of this development is to find applications for which the recycled materials could be used efficiently. The presented study deals with the development of recycled aggregate fibre reinforced concrete which is going to be used for an innovative precast concrete pavement system. The system is being developed recently at Czech Technical University in Prague with the aim to provide a system for airfield pavement with rapid construction and recycled material utilization. The investigated material is going to be used for construction of a sub-base course which is underneath a surface course of precast concrete elements. Within the scope of the work,standard laboratory tests were conducted with the aim to observe mechanical properties of recycled aggregate fibre reinforced concrete. The obtained findings showed that the material exhibits ductile behaviour likely due to very long polypropylene fibres used for strengthening concrete matrix. On the contrary, the tested material has low modulus of elasticity in comparison with conventional concrete. Subsequently, the pilot construction of the sub-base course was carried out in order to examine both concrete mixture preparation and concrete course installation in practice. The obtained findings showed that a compaction ratio of the material is about 20%. Moreover, a flat surface of the sub-base course was hard to achieve considering the used manufacturing technology. Keywords: pervious concret; fiber reinforced concrete; airfiled pavement; recycled aggregate; flexural strength Available in digital repository of ČVUT.
Study on pervious recycled aggregate fiber-reinforced concrete for airfield pavement

For the last several years, the attention has been devoted to the development of ecofriendly construction materials with the aim to reduce the environmental impact of construction. The integral part ...

Novák J.; Chylík R.; Trtík T.; Kohoutková A.
České vysoké učení technické v Praze, 2020

Standard Cell Tuning Enables Data-Independent Static Power Consumption
Bělohoubek J.; Fišer P.; Schmidt J.
2020 - English
Physical attacks, namely invasive, observation and combined, represent a great challenge for today’s digital design. Successful class of strategies adopted by industry, allowing hiding data dependency of the side channel emissions in CMOS is based on balancing. Although attacks on CMOS dynamic power represent a class of state-of-the-art attacks, vulnerabilities exploiting data dependency in CMOS static power and light- modulated static power were recently presented. In this paper, we describe structures and techniques developed to enhance and balance traditional static CMOS bulk structures. To enable data dependency hiding, we propose low-level techniques based on complementary-value induced balancing currents, constant current source behavioral approximation, and light-sensing capability of traditional CMOS structures. The proposed techniques may be used to build a dual-rail circuit balanced from both perspectives: static and dynamic power. The publicly available TSMC180nm node standard cell simulation is used for evaluation. Keywords: security; power attacks; laser illumination; CMOS Available in digital repository of ČVUT.
Standard Cell Tuning Enables Data-Independent Static Power Consumption

Physical attacks, namely invasive, observation and combined, represent a great challenge for today’s digital design. Successful class of strategies adopted by industry, allowing hiding data dependency ...

Bělohoubek J.; Fišer P.; Schmidt J.
České vysoké učení technické v Praze, 2020

Evaluation of the SEU Faults Coverage of a Simple Fault Model for Application-Oriented FPGA Testing
Borecký J.; Hülle R.; Fišer P.
2020 - English
Testing of FPGA-based designs persists to be a challenging task because of the complex FPGA architecture with heterogeneous components, and therefore a complicated fault model. The standard stuck-at fault model has been found insufficient. On the other hand, very precise FPGA fault models have been recently devised. However, these models are often excessively complex and require a lot of resources (run-time, memory) to manipulate with. In this paper, we propose a simple yet efficient combined fault model comprising bit-flips in look-up tables and stuck-at faults in the rest of logic. On~top of this model, a dedicated SAT-based application-oriented ATPG has been designed. The main contribution of this paper is the evaluation of efficiency of the fault model with the respective ATPG by exhaustive hardware emulation of all possible SEUs in the configuration memory that may influence the functionality of the circuit implemented in the FPGA. We show that the obtained fault coverage reaches up to more than 99%, which makes the method applicable in practice. Even though combinational circuits are assumed only, the method can be used to quickly test safety-critical combinational cores. Keywords: fault model; application-oriented testing; ATPG; SAT; FPGA; SEU Available in digital repository of ČVUT.
Evaluation of the SEU Faults Coverage of a Simple Fault Model for Application-Oriented FPGA Testing

Testing of FPGA-based designs persists to be a challenging task because of the complex FPGA architecture with heterogeneous components, and therefore a complicated fault model. The standard stuck-at ...

Borecký J.; Hülle R.; Fišer P.
České vysoké učení technické v Praze, 2020

Image analysis of particle size: effect of light source type
Formánek R.; Kysela B.; Šulc R.
2019 - English
Agitation of two immiscible liquids or solid-liquid suspension is a frequent operation in chemical and metallurgical industries. The sizes of particles, bubbles or droplets can be determined by the Image Analysis Technique. It is known that the quality of captured images depends significantly on the original image background that is mainly affected by the type of the light source. The aim of this contribution is to investigate the effect of light source type on image quality. The four types of light sources were tested: 1) 1000 W halogen lamp, 2) 72 W LED bar panel, 3) 60 W LED chip, and 4) 90 W LED chip. The illumination intensity and image background quality were investigated for each tested light sources. The effect of the shutter speed on evaluated particle sizes was tested using monodisperse spherical calibration particles having diameter of 1.19 mm. The difference observed between particle sizes evaluated by image analysis for given light source and declared calibration particle diameter was used as a measure of light source quality. Keywords: image analysis; light source Available in digital repository of ČVUT.
Image analysis of particle size: effect of light source type

Agitation of two immiscible liquids or solid-liquid suspension is a frequent operation in chemical and metallurgical industries. The sizes of particles, bubbles or droplets can be determined by the ...

Formánek R.; Kysela B.; Šulc R.
České vysoké učení technické v Praze, 2019

Rizika navrhování a rozhodování
Beran V.; Dlask P.; Faltová Leitmanová I.
2019 - Czech
Stávající stav navrhování nových projektů je v ČR primárně ovlivněn dlouhodobě poddimenzovaným objemem investic ve veřejném i privátním sektoru. Následkem je permisivní selekce návrhů projektů s nízkou přidanou hodnotou. Zpochybnitelné profesní přínosy a invence u investic vytváří dlouhodobě rizikové externality. Projevují se navýšením nákladů, odloženými termíny (plné) funkčnosti investic a degradací očekávaných výnosů. Čistý výnos investic se pohybuje dlouhodobě na úrovni 4-6%. Návrhy, které indikují nízkou úroveň efektivnosti a nejsou zamítány, zakládají degradační cyklus rizik: nákladů – termínů – výnosů – degradace věcné podstaty a návratnosti vložených zdrojů. Důsledkem jsou investiční celky s extrémně dlouhými termíny dokončení a překročení nákladů. Dohledání počátků zavlečeného investičního pochybení je zpravidla stejně tak obtížné, jako majoritou legislativních opatření nevyžadované. Nízká tempa regionálního rozvoje, degradace konkurenceschopnosti, jsou jen dílčím výčtem důsledků a technickoekonomických a sociálních (TES) rizik. Keywords: riziko; navrhování; rozhodování; tvorba kapitálu; HDP; rizika; překročení nákladů; rizika překročení termínů dokončení Available in digital repository of ČVUT.
Rizika navrhování a rozhodování

Stávající stav navrhování nových projektů je v ČR primárně ovlivněn dlouhodobě poddimenzovaným objemem investic ve veřejném i privátním sektoru. Následkem je permisivní selekce návrhů projektů s ...

Beran V.; Dlask P.; Faltová Leitmanová I.
České vysoké učení technické v Praze, 2019

Radio over 50 km Fiber and Joint 80 m FSO/Wireless Links Using Photonic Frequency Doubling for 5G
Bohata J.; Spáčil J.; Nguyen Dong N.; Zvánovec S.; Vallejo L.; Ortega B.
2019 - English
We present the experimental demonstration of photonic doubling to achieve 25 GHz millimeter wave signal generation, following the 5th generation network frequency band recommendations. A hybrid optical network combining up to 50 km long radio over fiber and 40 m long radio over free space optics systems plus 40 m long radio frequency (RF) 25 GHz wireless channel is demonstrated. The proposed system employs double sideband suppressed carrier modulation with 27 dB optical carrier suppression ratio and RF carrier phase noise below - 107 dBc/Hz with 10 kHz offset. Furthermore, the proposed system is optimized in terms of RF input power and the system quality is tested in terms of error vector magnitude for different modulation formats and variable fiber section lengths. Keywords: Microwave photonics; radio over fiber; free space optics; millimeter wave. Available in digital repository of ČVUT.
Radio over 50 km Fiber and Joint 80 m FSO/Wireless Links Using Photonic Frequency Doubling for 5G

We present the experimental demonstration of photonic doubling to achieve 25 GHz millimeter wave signal generation, following the 5th generation network frequency band recommendations. A hybrid ...

Bohata J.; Spáčil J.; Nguyen Dong N.; Zvánovec S.; Vallejo L.; Ortega B.
České vysoké učení technické v Praze, 2019

Development Analysis of Cyber Security Incidents in the Czech Republic
Bernátek J.
2019 - English
The paper deals with the legislative and organizational anchorage of cybersecurity in the Czech Republic, including the statistical analysis of the development of cybersecurity incidents registered by the National and Government CERT for the period of 2008-2018. In the given period, there was a decrease in cybersecurity incidents registered by the Government CERT, but an increase in incidents registered by the National CERT. The aim of the paper is also to provide proposals for measures to prevent and combat cyber-attacks more effectively. Keywords: cybersecurity; cyber incident; cyber event; cyberattack Available in digital repository of ČVUT.
Development Analysis of Cyber Security Incidents in the Czech Republic

The paper deals with the legislative and organizational anchorage of cybersecurity in the Czech Republic, including the statistical analysis of the development of cybersecurity incidents registered by ...

Bernátek J.
České vysoké učení technické v Praze, 2019

All-Inkjet Printed Flexible Capacitors Utilizing SU-8 and PVP Dielectric Inks
Povolný V.; Puci F.
2019 - English
This paper presents fabrication of printed interdigital capacitors on a flexible and lightweight polyester (PET) substrate. Capacitors were fabricated using inkjet printing technology and conventional low temperature (100-150°C) curing method. The surface of printed capacitors were covered with dielectric material, which lend capacitor a specific value of permittivity, but also serves as protective coating. Cross-linked poly-4- vinylphenol (cPVP) and SU-8 were applied as dielectric materials and experimental results are compared. Keywords: Inkjet; Printed electronics; Passive electronic components Available in digital repository of ČVUT.
All-Inkjet Printed Flexible Capacitors Utilizing SU-8 and PVP Dielectric Inks

This paper presents fabrication of printed interdigital capacitors on a flexible and lightweight polyester (PET) substrate. Capacitors were fabricated using inkjet printing technology and conventional ...

Povolný V.; Puci F.
České vysoké učení technické v Praze, 2019

Thermal errors of a 5-axis CNC milling centre equipped with different spindle units
Horejš O.; Mareš M.; Hornych J.
2019 - English
Thermally induced errors are dominant sources of inaccuracy and are often the most difficult types of errors to reduce today. Software compensation of thermally induced displacements at the TCP is a widely employed technique to reduce these errors due to its cost-effectiveness and ease of implementation. Furthermore, machine tool manufacturers frequently offer a particular type of machine tool in multiple versions, where each version is equipped with a different spindle unit. This leads to different thermal deformation behaviour depending on the specific spindle unit mounted in the machine tool. To demonstrate this difference, an experimental research on a three 5-axis CNC milling centres of the same type equipped with three different spindle units is presented in this paper. Experimentally obtained thermal errors at the TCP from 3 machine tools with different mounted spindle units are mutually compared, showing a significant variation in thermal errors in the Z direction depending on the spindle unit. This fact should be taken into consideration in development of thermal error compensation models, as shown in the case of a modelling approach using transfer functions for a tested 5-axis CNC milling centre. Keywords: Thermal error; Spindle unit; Accuracy; Compensation Available in digital repository of ČVUT.
Thermal errors of a 5-axis CNC milling centre equipped with different spindle units

Thermally induced errors are dominant sources of inaccuracy and are often the most difficult types of errors to reduce today. Software compensation of thermally induced displacements at the TCP is a ...

Horejš O.; Mareš M.; Hornych J.
České vysoké učení technické v Praze, 2019

Experiments for Predictable Execution of GPU Kernels
Kreiliger F.; Matějka J.; Sojka M.; Hanzálek Z.
2019 - English
Multi-Processor Systems-on-Chip (MPSoC) platforms will definitely power various future autonomous machines. Due to the high complexity of such platforms, it is difficult to achieve timing predictability, reliability and efficient resource utilization at the same time. We believe that time-triggered scheduling in combination with PRedictable Execution Model (PREM) can provide strong safety guarantees, and our longerterm goal is to schedule execution on the whole MPSoC (CPUs and GPU) in time triggered manner. To extend PREM to GPUs, we compare two synchronization mechanisms available on the NVIDIA Tegra X2 platform: one based on pinned memory and another that uses a GPU timer (socalled globaltimer). We found that running the NVIDIA profiler (nvprof) reconfigures the resolution of the globaltimer from 1 µs to 160 ns. By using time-triggered scheduling with such a resolution,itwaspossibletoreduceexecutiontimejitterofatiled 2D convolution kernel from 6.47% to 0.15% while maintaining the same average execution time. Keywords: predictable execution; gpu; nvidia; tx2; prem Available in digital repository of ČVUT.
Experiments for Predictable Execution of GPU Kernels

Multi-Processor Systems-on-Chip (MPSoC) platforms will definitely power various future autonomous machines. Due to the high complexity of such platforms, it is difficult to achieve timing ...

Kreiliger F.; Matějka J.; Sojka M.; Hanzálek Z.
České vysoké učení technické v Praze, 2019

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