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The ballast pick-up problem in high speed trains
Sanz-Andres, Angel; Navarro-Medina, Fermín
2010 - anglický
When a high speed train overpasses a critical speed produces a wind speed close to the track large enough to start the motion of the ballast elements, eventually leading to the rolling of the stones and, if they get enough energy, they can jump and then initiate a saltation-like chain reaction. In this contribution a mathematical model of the initiation of the motion is presented. The dynamics of the stone is formulated taking into account both gravity and aerodynamic forces. These aerodynamic forces are the result of the train-generated-gust impinging on the stones. Although they are intrinsically non steady, under some conditions a cuasi-steady aerodynamic model can be employed. Conditions for the start of the
motion are obtained in terms of the Tachikawa number (a kind of Froude number). The aerodynamic
characteristics are included in terms of the zero aerodynamic moment line of the stone, and the
aerodynamic moment coefficient.
Klíčová slova:
high speed trains; ballast; saltation; modelization
Plné texty jsou dostupné v digitálním repozitáři UPCE.
The ballast pick-up problem in high speed trains
When a high speed train overpasses a critical speed produces a wind speed close to the track large enough to start the motion of the ballast elements, eventually leading to the rolling of the stones ...
Walking as a sustainable transport mode in cities
Schmeidler, Karel
2010 - anglický
Spatial mobility - a basic human need for movement influences the overall development of society. The present day offers many kinds of means of transport and ways how to move fast even at a long distance in the global world. Fascination by this previously unknown possibility - to travel all
over the world in a relatively short time - often diverts attention from the most natural and also
the healthiest modes of transport. Walking indeed is the first and basic transport mode, and when extreme cases such as the handicapped, injured and for other reasons walking - incapable people are left out, it is also the healthiest and most typical transport mode of human beings. Unfortunately, the benefit of walking is nowadays often disregarded and replaced with other means of transport - most frequently individual car traffic. Present - day cities have changed into car areas in which pedestrians are pushed out by danger, noise, and combustion gases produced by columns of stopping and starting vehicles. Parking cars obstruct pedestrians' view and movement. The liberty of walking in city centres can be regarded as an attribute of a free personality according to The Charter of Fundamental Rights and Freedoms.
Klíčová slova:
walking; pedestrians; walkability; urban space; non-motorised modes of transport
Plné texty jsou dostupné v digitálním repozitáři UPCE.
Walking as a sustainable transport mode in cities
Spatial mobility - a basic human need for movement influences the overall development of society. The present day offers many kinds of means of transport and ways how to move fast even at a long ...
Improving passive safety by computer simulation
Štych, Jan
2010 - anglický
Increasing of safety is necessarily - as every other development - a trial and error process.
Traditional way to verify the results of development is construction and testing of many prototypes. This is time consuming and expensive. Proven alternative is a virtual simulation. Automotive industry was the first using it almost exclusively for crash tests. This remains the main role today, but the development of technology and increasing of computer power has enabled usage of simulation in new areas. Today is simulation used in the process of manufacturing (stamping, welding ...) and allows direct analysis of the influence of the manufacturing process in crash test result. Simulation gives an accurate description of inflating behavior of airbags. Simulation is also used in comfort, for example in the development of car seats is possible to evaluate effect of vibration transmitted to occupants. Simulation can be used to test the durability of road barriers, where you can virtually check the behavior
before physical test. Company ESI Group, a leading global supplier and innovator in this field, has a constantly evolving portfolio of software tools enabling realistic and predictive simulations.
The effectiveness of software tools is enhanced by a common environment to define the role and easy portability of the results from one area to another simulation, i.e. you can make very accurate simulation of crash tests, with the influence of manufacturing processes of individual components. MECAS ESI, Czech branch of ESI Group, provides distribution of computer simulation tools and support in Central and Eastern Europe.
Klíčová slova:
simulation; crash; safety; FEM
Plné texty jsou dostupné v digitálním repozitáři UPCE.
Improving passive safety by computer simulation
Increasing of safety is necessarily - as every other development - a trial and error process. Traditional way to verify the results of development is construction and testing of many prototypes. This ...
Measuring and valuing travel time reliability – an example for hard shoulder operation
Vuren, Tom
2010 - anglický
Most transport infrastructure investments aim to reduce average travel times and their appraisal
depends to a large extent on travel time savings and their value. There is an increasing recognition that
in addition to average travel times, their reliability affects travelers’ choices and their valuation. However, the representation of travel time variability in network models, and hence our ability to forecast future impacts on reliability, has been limited. New data sources have enabled us to establish relationships between readily measurable characteristics and travel time variability. This now allows us to incorporate reliability in project appraisal, using standard economic cost-benefit techniques. The paper
illustrates the method with an example of hard shoulder operations on Motorways around Birmingham
in England.
Klíčová slova:
economic appraisal; travel time variability; hard shoulder operation
Plné texty jsou dostupné v digitálním repozitáři UPCE.
Measuring and valuing travel time reliability – an example for hard shoulder operation
Most transport infrastructure investments aim to reduce average travel times and their appraisal depends to a large extent on travel time savings and their value. There is an increasing recognition ...
The application of fuzzy logic to a simulation of railway station
Záhorová, Věra
2010 - anglický
This article is a contribution to investigation concerning development of a simulation model
of a passenger railway-station. Concretely to a part of this research, which is related to a problem, how to simulate a choice of a platform line to a delayed train. Potentiality of different methods of a computational intelligence to this task handling was reviewed. Although another method – an evaluation of options – was used for construction of simulation model [3], an applicable result was obtained also using fuzzy controller. An idea of fuzzy inference and of fuzzy system structure is described in this paper
at some length. Following part is especially focused on a way how to create a fuzzy rules base. Last part of paper shows some results obtained in the process of creation of a Mamdani fuzzy logic controller and in the course of verification of its ability to choose a line to a delayed train correctly.
Klíčová slova:
simulation; fuzzy controller; rules base; railway
Plné texty jsou dostupné v digitálním repozitáři UPCE.
The application of fuzzy logic to a simulation of railway station
This article is a contribution to investigation concerning development of a simulation model of a passenger railway-station. Concretely to a part of this research, which is related to a problem, how ...
Stability Control of Renewable Energy Sources in Distribution Systems
Tlustý, Josef; Müller, Zdeněk; Valouch, Viktor
2010 - anglický
Deregulation in the power market has encouraged the move towards distributed generation, where many smaller generating plants located close to major loads are penetrating into interconnected power systems. When the penetration level increases, several other problems will need to be faced and solved. Stability problems may arise, new planning tools will be needed, dispatching of energy sources with typical random production will be necessary, protection systems must be integrated and revised. In order to simulate power system dynamics programmable opened software in Matlab – DynaSolv was developed. The paper describes various principles of penetration synchronous machine type DGS into distribution network. This study provides possible complex analysis view on DGS stability issues, which can answer the possibility of connection.
Klíčová slova:
stability; distributed generation; globally penetrated system; eigenvalues
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
Stability Control of Renewable Energy Sources in Distribution Systems
Deregulation in the power market has encouraged the move towards distributed generation, where many smaller generating plants located close to major loads are penetrating into interconnected power ...
The risk rate by ADR road transport of dangerous matters
Brožová, Pavlína
2010 - anglický
The paper will be focused on the questions of ADR road transport of dangerous matters, especially on the risks estimation of transport of dangerous goods in the Czech Republic. The risks estimation is the basic presumption for safety increment by this type of risk transport. The aim of the paper is to refer to the risks, which may occur not only in the case of traffic accidents, but also by influence of the various logistics activities. There is also an endeavour to minimization of these risks in the paper.
Klíčová slova:
road transport; risk; dangerous matters
Plné texty jsou dostupné v digitálním repozitáři UPCE.
The risk rate by ADR road transport of dangerous matters
The paper will be focused on the questions of ADR road transport of dangerous matters, especially on the risks estimation of transport of dangerous goods in the Czech Republic. The risks estimation is ...
The technological model of operating area by the combined transport
Cempírek, Václav; Široký, Jaromír; Císařová, Hana
2010 - anglický
The contribution deals with design technology service model using the combined transport.
It assesses the performance indicators in relation to price and quality of services provided and on this basis decides on the type of the transport. This is the decision-making processes, which should answer the question, whether used directly in road freight transport, direct rail freight transport or combined transport. In this contribution is the combined transport meant as a system between the conventional modes, which are transhipped goods from road vehicles to the rail cars or river boats.
Klíčová slova:
hub location; heuristic and metaheuristic methods; combined transport
Plné texty jsou dostupné v digitálním repozitáři UPCE.
The technological model of operating area by the combined transport
The contribution deals with design technology service model using the combined transport. It assesses the performance indicators in relation to price and quality of services provided and on this ...
Shunting freight cars with own power units
Dahlhaus, Elias
2010 - anglický
In this paper it is shown that shunting freight cars can be simplified significantly if the freight cars have their own power unit. Freight with own power units are extensively discussed in the project FlexCargoRail.
Klíčová slova:
FlexCargoRail; merge sort; permutation graph coloring
Plné texty jsou dostupné v digitálním repozitáři UPCE.
Shunting freight cars with own power units
In this paper it is shown that shunting freight cars can be simplified significantly if the freight cars have their own power unit. Freight with own power units are extensively discussed in the ...
Electric automobil - wishes and reality
Duchoň, Bedřich; Opava, Jaroslav
2010 - anglický
The demands on cars energy resources are given by the following items: power, speed, acceleration, operation range. All these factors are under balance: future wishes and contemporary reality.
The proposal is dedicated to the analysis of demands related to the electric automobiles.
As a hopefulness solution of these transport means can be seen for city transport (forwarding, shopping, postal services etc). The technical and economic approaches are discussed, too.
Klíčová slova:
power; energy; operating range; electric drive; application; economics
Plné texty jsou dostupné v digitálním repozitáři UPCE.
Electric automobil - wishes and reality
The demands on cars energy resources are given by the following items: power, speed, acceleration, operation range. All these factors are under balance: future wishes and contemporary reality. The ...
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