Number of found documents: 340
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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

A comparative study of synchronverter stability
Vetoshkin L.; Müller Z.
2020 - English
Electric grids, after a large scale installation of renewable energy sources, have dramatically changed. One of the major concerns in the operation of the modern power system is low grid inertia. Different approaches are being proposed to overcome this challenge. However, the prevalent idea is to introduce virtual inertia to the system using a sophisticated control strategy of power electronics in the electric grids. This paper investigates the synchronverter, which is a possible solution to the mentioned problem. The first chapter briefly describes the problem and the synchronverter control strategy of power converters. The second chapter provides a mathematical model of the synchronverter in d-q frame connected to an infinite bus. Furthermore, it analysis the small signal stability of the synchronverter. The third chapter gives a brief overlook of small signal stability of traditional vector control. Moreover, this chapter provides a comparison between the researched approach and the conventional one. Keywords: Mathematical model; Inverters; Virtual Inertia; Synchronverter Available in digital repository of ČVUT.
A comparative study of synchronverter stability

Electric grids, after a large scale installation of renewable energy sources, have dramatically changed. One of the major concerns in the operation of the modern power system is low grid inertia. ...

Vetoshkin L.; Müller Z.
České vysoké učení technické v Praze, 2020

Photodetectors for cylindrical illuminance sensor
Kozlok M.; Žák P.
2020 - English
The paper describes the basic principles of illuminance measurement and possibilities of multi-point measurement of light field spatial properties. Based on the research, the description contains three steps of the development of a multi-point cylindrical illuminance sensor and their hardware architectures. The development aims to create a functional prototype that would allow measurement in addition to one scalar quantity of cylindrical illuminance also the prevailing direction of light in one plane in space, symmetrical, diffuse component, and visual appearance indicator calculated from the ratio of horizontal and cylindrical illuminance. Keywords: photodiode; photodetector; illuminance; cylindrical illuminance; illuminance vector Available in digital repository of ČVUT.
Photodetectors for cylindrical illuminance sensor

The paper describes the basic principles of illuminance measurement and possibilities of multi-point measurement of light field spatial properties. Based on the research, the description contains ...

Kozlok M.; Žák P.
České vysoké učení technické v Praze, 2020

Supplementary damping control design for large scale PV power plant at transmission level interconnection
Isbeih Y.J.; Shawky El Moursi M.; Lotfi M.; Catalao J.P.S.; Abdelwahab M.
2020 - English
The deployment of large scale photovoltaic (PV) power generation has been witnessed in several countries worldwide with different installed capacities. Accordingly, codes and regulations to ensure secure and economical operation have been revised to address the challenges related with PV integration into electrical networks. This paper presents an H∞ mixed sensitivity robust control design for enhancing the overall damping of low frequency oscillations. The presented architecture will implement the output signal of the power oscillator damper (POD) at the control loop of the PV-based solar power plant. The effectiveness of the proposed approach is tested using the New-England, 10machines test system. Available in digital repository of ČVUT.
Supplementary damping control design for large scale PV power plant at transmission level interconnection

The deployment of large scale photovoltaic (PV) power generation has been witnessed in several countries worldwide with different installed capacities. Accordingly, codes and regulations to ensure ...

Isbeih Y.J.; Shawky El Moursi M.; Lotfi M.; Catalao J.P.S.; Abdelwahab M.
České vysoké učení technické v Praze, 2020

Matematický model provozu deskového otopného tělesa
Boháč J.; Bašta J.
2020 - Czech
Příspěvek shrnuje poznatky týkající se experimentálního sledování a modelování nestacionárního chování otopných těles. Je popsán komplexní model využívající aproximaci podle Strejce a také matematický diskrétní ARX black-box model v softwaru Matlab (ukázka pro deskové otopné těleso 10 – 500 x 1000), včetně jejich předpokladů a okrajových podmínek. Cílem bylo nalezení takového způsobu stanovení rozhodujících parametrů popisujících dynamiku otopných těles a vlastní vyhodnocení dynamického děje, na jehož základě by bylo možné aplikovat model pro různá otopná tělesa, a to bez nutnosti jejich měření v akreditovaných laboratořích. Uvedený model je nástroj poskytující možnost zjišťovat dynamiku velice rychle a takto získané údaje mohou být základem pro návrh a optimalizaci funkce regulátorů tepelného výkonu, ale také podkladem pro jejich optimální součinnost například s konkrétním typem otopného tělesa. Keywords: dynamics; modelling; Matlab; radiator; control Available in digital repository of ČVUT.
Matematický model provozu deskového otopného tělesa

Příspěvek shrnuje poznatky týkající se experimentálního sledování a modelování nestacionárního chování otopných těles. Je popsán komplexní model využívající aproximaci podle Strejce a také matematický ...

Boháč J.; Bašta J.
České vysoké učení technické v Praze, 2020

Light trespass in street LED lighting systems
Bálský M.; Terrich T.
2020 - English
Increasing the efficiency of lighting systems can be achieved not only by increasing the luminous efficacy of the light sources, but also by reducing the useless luminous flux, which is referred to as the light trespass. The luminous flux is in artificial lighting systems generated from electrical power and therefore the light trespass means the loss of electrical power. The paper deals with the possibilities of increasing the efficiency of street lighting by optimizing the luminous flux distribution of luminaires and its influence on the light trespass. Keywords: Street Lighting; Luminaire; Light Trespass; Luminous Flux; Luminous Intensity Distribution; Light Emitting Diode; High Pressure Sodium Lamp Available in digital repository of ČVUT.
Light trespass in street LED lighting systems

Increasing the efficiency of lighting systems can be achieved not only by increasing the luminous efficacy of the light sources, but also by reducing the useless luminous flux, which is referred to as ...

Bálský M.; Terrich T.
České vysoké učení technické v Praze, 2020

Comparison of power control method for B4 converter connected to unbalanced grid
Simek P.; Valouch V.
2020 - English
The aim of the paper is to present a power control of a three-phase inverter with only four inverter legs (connections B4) connected to an unbalanced grid. The results obtained by the predictive power control with a finite set of control values, the results obtained using a modified direct power control strategy, and the results obtained using a generalized predictive control are compared and discussed. Keywords: power control; B4 converter; unbalanced grid; modified reactive power theory; predictive control component Available in digital repository of ČVUT.
Comparison of power control method for B4 converter connected to unbalanced grid

The aim of the paper is to present a power control of a three-phase inverter with only four inverter legs (connections B4) connected to an unbalanced grid. The results obtained by the predictive power ...

Simek P.; Valouch V.
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

Electricity Storage in Internet of Renewable Energy (IoRE) Domain for Sustainable Smart Cities
Igbinovia F.O.; Krupka J.; Hajek P.; Müller Z.; Tlustý J.
2020 - English
Electricity storage is essential to permitting the advocacy of a purely renewable electricity grid architecture. This will be the utmost resolution for devoting only random renewable electricity resources like wind and solar plants, to only meet utility base load demand of electricity consumers. Electricity storage is one of the key facilitating equipment's for the future purely renewable electricity grid architecture. Which when intelligently controlled using Internet of Renewable Energy (IoRE) has the attributes that will reward both residential/industrial electricity consumers, and electricity utility authorities. Thereby making it possible to initiate new electricity market models and smart management of cities. This write up is influenced with the desire to give perception into the prospective utilization of electricity storage technology in IoRE domain for clean and sustainable smart city implementation. Keywords: electricity storage; Internet of Renewable Energy (IoRE); purely renewable electricity grid; smart cities; sustainable smart cities Available in digital repository of ČVUT.
Electricity Storage in Internet of Renewable Energy (IoRE) Domain for Sustainable Smart Cities

Electricity storage is essential to permitting the advocacy of a purely renewable electricity grid architecture. This will be the utmost resolution for devoting only random renewable electricity ...

Igbinovia F.O.; Krupka J.; Hajek P.; Müller Z.; Tlustý J.
České vysoké učení technické v Praze, 2020

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