Number of found documents: 2111
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Analysis, Modeling and Enhancement of Scientific Images
Švihlík, Jan
2020 - English
Available in digital repository of ČVUT.
Analysis, Modeling and Enhancement of Scientific Images

Švihlík, Jan
České vysoké učení technické v Praze, 2020

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

RISK MANAGEMENT AT TECHNICAL FACILITIES DESIGNING, BUILDING AND COMMISSIONING
Procházková D.; Procházka J.
2020 - English
The publication subject is to show the risk management of complex technical facilities at a stage involving the design, construction, outfit by technology equipment, testing and commissioning. The safety of this technical facility is related to the entire technical facility because, as a result of the interconnections among different parts, the set of the safe parts is generally not safe. The safety also considers the dynamic evolution of the world. Therefore, it is going on managing the risks caused by all possible causes in time and space. Based on the original database of failures and accidents of technical facilities, which also included weaknesses in the area of design, building, construction, testing and commissioning, they are determined the basic categories of risk causes. Through the procedures of advanced risk disciplines, there are developed the tools for working with risks in the monitored stage of the technical facility aimed at ensuring the technical facility safety throughout its life time, namely: decision support system; and risk management plan. Both tools are in two versions. The book shortly summarizes results of specific research performed in project “Řízení rizik a bezpečnost složitých technologických objektů (RIRIZIBE)“ CZ.02.2.69/0.0 /0.0/16_018/000”. The detail results are in original Czech monograph, which is cited. Keywords: technical facility; risk; safety; risk engineering; decision support system; risk management plan Available in digital repository of ČVUT.
RISK MANAGEMENT AT TECHNICAL FACILITIES DESIGNING, BUILDING AND COMMISSIONING

The publication subject is to show the risk management of complex technical facilities at a stage involving the design, construction, outfit by technology equipment, testing and commissioning. The ...

Procházková D.; Procházka J.
České vysoké učení technické v Praze, 2020

Many-valued conjunctions
Petrík, Milan
2020 - English
Available in digital repository of ČVUT.
Many-valued conjunctions

Petrík, Milan
České vysoké učení technické v Praze, 2020

CONTROLLED INDUCTION MOTOR DRIVE IN RAILWAY TRACTION
Bauer, Jan
2020 - English
This habilitation thesis presents improvements in selected areas of induction motor drive application in railway traction vehicles. One of the most common induction motor control strategies in railway traction drives, is the Rotor Flux-Oriented Control. To reach high performance and high efficiency of the drive, precise knowledge of the induction motor equivalent circuit parameters is needed. Inaccurate knowledge of the induction motor equivalent circuit parameters leads to FOC detuning, which causes misalignment of the estimated flux position and, thus, inaccuracy of the whole control part. The problematics of induction motor drive parameter identification and accuracy of the induction motor model is one of the key points of the thesis. The other part of the thesis describes a slip controller's development for freight locomotive with the induction motor drive, that is based on adhesion-slip characteristic slope detection. The proposed slip controller is designed to cope with a nonlinearity of the adhesion-slip characteristic and noise that occurs in the system. Moreover, the proposed slip controller does not need to know the train velocity, the wheelset velocity is only required parameter. The slip controller is designed as modular, and it consists of the adhesion-slip characteristic slope detection part and a controller part with acceleration protection. Keywords: Induction Motor; Adhesion Characteritsc; Field Oriented Control; Slip; Asynchronní motor; vektorové řízení; adhezní charakteristika; skluz Available in digital repository of ČVUT.
CONTROLLED INDUCTION MOTOR DRIVE IN RAILWAY TRACTION

This habilitation thesis presents improvements in selected areas of induction motor drive application in railway traction vehicles. One of the most common induction motor control strategies in ...

Bauer, Jan
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

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

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