10 research outputs found
Performance Analysis of Train Communication Systems
Trains are considered as a highly efficient transport mode which generate significant
challenges in terms of their communication systems. For improved safety, to cope with
the expected rapid increase in traffic, and to meet customer demands, an enhanced
and reliable communication system is required for high-speed trains (HSRs). Mobile
phone and laptop users would like to make use of the non-negligible time that they
spend commuting but current HSR communication systems have a foreseeable end
to their lifetime and a reliable, efficient, and fast communication replacement system
has become essential. Encouraged by the use of existing power line networks for
communication purposes, this research investigates the possibility of developing a train
communication system based on the use of overhead line equipment (OLE). The ABCD
transfer line model is developed to represent the transfer function of the OLE channel
and is evaluated using computer simulations. The simulations of the OLE system used
are based on orthogonal frequency division multiplexing as the chosen modulation
scheme.
Within the train, for the provision of broadband services, developing a reliable
communication system which is a combination of power line communication and
optical wireless communication services using visible light communication (VLC)
is considered. Mathematical methods were developed for these networks to assess
the overall capacities and outage probabilities of the hybrid systems. Derivation of
such analytical expressions offered opportunities to investigate the impact of several
system parameters on the performance of the system. To assess the possibility of
improving the performance of the proposed integrated systems, their performance in
the presence of different relaying protocols has been comprehensively analyzed in
terms of capacity and outage probability. This thesis studied the outage probability and
energy per bit consumption performance of different relaying protocols over the VLC
channel. Accurate analytical expressions for the overall outage probability and energyper-bit consumption of the proposed system configurations, including the single-hop
and multi-hop approaches were derived.
It was found that the transfer function of the OLE channel can be represented by the
two-port network model. It was also revealed that transmission over OLE is negatively
affected by the speed of the train, frequency, and length of the OLE link. In train, relay-based communication systems can provide reliable connectivity to the end-user.
However, choosing an optimal system configuration can enhance system performance.
It was also shown that increasing relay numbers on the network contributes to the total
power consumption of the system
Towards the Internet of Smart Trains: A Review on Industrial IoT-Connected Railways
[Abstract] Nowadays, the railway industry is in a position where it is able to exploit the opportunities created by the IIoT (Industrial Internet of Things) and enabling communication technologies under the paradigm of Internet of Trains. This review details the evolution of communication technologies since the deployment of GSM-R, describing the main alternatives and how railway requirements, specifications and recommendations have evolved over time. The advantages of the latest generation of broadband communication systems (e.g., LTE, 5G, IEEE 802.11ad) and the emergence of Wireless Sensor Networks (WSNs) for the railway environment are also explained together with the strategic roadmap to ensure a smooth migration from GSM-R. Furthermore, this survey focuses on providing a holistic approach, identifying scenarios and architectures where railways could leverage better commercial IIoT capabilities. After reviewing the main industrial developments, short and medium-term IIoT-enabled services for smart railways are evaluated. Then, it is analyzed the latest research on predictive maintenance, smart infrastructure, advanced monitoring of assets, video surveillance systems, railway operations, Passenger and Freight Information Systems (PIS/FIS), train control systems, safety assurance, signaling systems, cyber security and energy efficiency. Overall, it can be stated that the aim of this article is to provide a detailed examination of the state-of-the-art of different technologies and services that will revolutionize the railway industry and will allow for confronting today challenges.Galicia. Consellería de Cultura, Educación e Ordenación Universitaria; ED431C 2016-045Galicia. Consellería de Cultura, Educación e Ordenación Universitaria; ED341D R2016/012Galicia. Consellería de Cultura, Educación e Ordenación Universitaria; ED431G/01Agencia Estatal de Investigación (España); TEC2013-47141-C4-1-RAgencia Estatal de Investigación (España); TEC2015-69648-REDCAgencia Estatal de Investigación (España); TEC2016-75067-C4-1-
A distributed topology control technique for low interference and energy efficiency in wireless sensor networks
Wireless sensor networks are used in several multi-disciplinary areas covering a wide variety of applications. They provide distributed computing, sensing and communication in a powerful integration of capabilities. They have great long-term economic potential and have the ability to transform our lives. At the same time however, they pose several challenges – mostly as a result of their random deployment and non-renewable energy sources.Among the most important issues in wireless sensor networks are energy efficiency and radio interference. Topology control plays an important role in the design of wireless ad hoc and sensor networks; it is capable of constructing networks that have desirable characteristics such as sparser connectivity, lower transmission power and a smaller node degree.In this research a distributed topology control technique is presented that enhances energy efficiency and reduces radio interference in wireless sensor networks. Each node in the network makes local decisions about its transmission power and the culmination of these local decisions produces a network topology that preserves global connectivity. The topology that is produced consists of a planar graph that is a power spanner, it has lower node degrees and can be constructed using local information. The network lifetime is increased by reducing transmission power and the use of low node degrees reduces traffic interference. The approach to topology control that is presented in this document has an advantage over previously developed approaches in that it focuses not only on reducing either energy consumption or radio interference, but on reducing both of these obstacles. Results are presented of simulations that demonstrate improvements in performance. AFRIKAANS : Draadlose sensor netwerke word gebruik in verskeie multi-dissiplinêre areas wat 'n wye verskeidenheid toepassings dek. Hulle voorsien verspreide berekening, bespeuring en kommunikasie in 'n kragtige integrate van vermoëns. Hulle het goeie langtermyn ekonomiese potentiaal en die vermoë om ons lewens te herskep. Terselfdertyd lewer dit egter verskeie uitdagings op as gevolg van hul lukrake ontplooiing en nie-hernubare energie bronne. Van die belangrikste kwessies in draadlose sensor netwerke is energie-doeltreffendheid en radiosteuring. Topologie-beheer speel 'n belangrike rol in die ontwerp van draadlose informele netwerke en sensor netwerke en dit is geskik om netwerke aan te bring wat gewenste eienskappe het soos verspreide koppeling, laer transmissiekrag en kleiner nodus graad.In hierdie ondersoek word 'n verspreide topologie beheertegniek voorgelê wat energie-doeltreffendheid verhoog en radiosteuring verminder in draadlose sensor netwerke. Elke nodus in die netwerk maak lokale besluite oor sy transmissiekrag en die hoogtepunt van hierdie lokale besluite lewer 'n netwerk-topologie op wat globale verbintenis behou.Die topologie wat gelewer word is 'n tweedimensionele grafiek en 'n kragsleutel; dit het laer nodus grade en kan gebou word met lokale inligting. Die netwerk-leeftyd word vermeerder deur transmissiekrag te verminder en verkeer-steuring word verminder deur lae nodus grade. Die benadering tot topologie-beheer wat voorgelê word in hierdie skrif het 'n voordeel oor benaderings wat vroeër ontwikkel is omdat dit nie net op die vermindering van net energie verbruik of net radiosteuring fokus nie, maar op albei. Resultate van simulasies word voorgelê wat die verbetering in werkverrigting demonstreer.Dissertation (MEng)--University of Pretoria, 2010.Electrical, Electronic and Computer Engineeringunrestricte
Probing the phase diagram of the Ferromagnetic Superconductor UGe2 using high pressure ultrasonic techniques
The main goal of the project was to develop new experimental techniques
to further investigate the phase diagram of the ferromagnetic superconductor
UGe2 at high pressures. Of particular interest is the metamagnetic transition
(FM1-FM2) which is thought to play the key role in the unconventional
superconductivity in UGe2. The project attempted to detect experimentally the
critical ferromagnetic fluctuations associated with the FM1-FM2 transition.
The development of the experimental equipment constitutes a substantial part of
the project and includes: (1) a 2-axis Rotation Stage for High Pressures, (2) an
Ultrasonic Sapphire Anvil Cell and (3) a High Pressure Pulse Echo Setup. (1)
allows transport measurement on single crystal samples with simultaneous two-axis
rotation at temperatures down to 2 K, magnetic fields up to 9T and pressures
up to 5GPa to be made. (2) employs Resonant Ultrasound Spectroscopy on a
sample in the anvil type cell with an optical access at cryogenic temperatures. (3)
uses the Pulse Echo Technique inside a cylinder type cell allowing for ultrasonic
measurements on samples with a well-defined orientation. The design, technical
challenges and tests results are presented and discussed.
The existing techniques, used in the project, included Inelastic Neutron Scattering.
A single crystal of UGe2 was studied at 12 kbar with a large volume
two-layered piston-cylinder cell. No critical fluctuations were detected at Tx
associated with the FM1-FM2 transition. Instead, a small inelastic signal below
this transition temperature was observed at the threshold of the instrument
sensitivity. The fluctuations at TC associated with the paramagnetic-to-ferromagnetic
transition (PM-FM) were detected and the energy scale of these fluctuations was found to have decreased, as compared to the ambient pressure
case, in proportion to the resistivity - a result supporting recent theory.
The elastic constant c11 of a single crystal of UGe2 was measured as a function
of temperature using (3) at ambient pressure as well as pressures up to 11 kbar.
The elastic constant exhibits clear features associated with the two transitions,
PM-FM and FM1-FM2. The temperature dependence of the elastic constant at
ambient pressure was modelled with two main contributions (Schottky-like and
Wiess-like) to the magnetic heat capacity coming from the two energy scales,
Tx and TC, as well as two corresponding Gruneisen parameters, Ωx and ΩC.
The values of Gruneisen parameters obtained from the data fitting were in good
agreement with the values determined from the slope of the phase transition lines
on the phase diagram. The temperature dependence of the elastic constant at
high pressures was modelled according to the two-component system with coupled
moments. The behaviour of the fitting parameters (including the Ωx and ΩT ) was
consistent with the phase diagram of UGe2 and captured important features of
c11 temperature evolution.
The way forward would be to continue the measurements of c11 at higher pressures
but also to repeat the measurements at different ultrasonic frequencies in order
to obtain the temperature dependence of the ultrasonic attenuation which will
provide more insight on the FM1-FM2 transition
Supramolecular Chemistry in the 3rd Millennium
This Special Issue is one of the first for the new MDPI flagship journal Chemistry (ISSN 2624-8549) which has a broad remit for publishing original research in all areas of chemistry. The theme of this issue is Supramolecular Chemistry in the 3rd Millennium and I am sure that this topic will attract many exciting contributions. We chose this topic because it encompasses the unity of contemporary pluridisciplinary science, in which organic, inorganic, physical and theoretical chemists work together with molecular biologists and physicists to develop a systems-level understanding of molecular interactions. The description of supramolecular chemistry as ‘chemistry beyond the molecule’ (Jean-Marie Lehn, Nobel Lecture and Gautam R. Desiraju, Nature, 2001, 412, 397) addresses the wide variety of weak, non-covalent interactions that are the basis for the assembly of supramolecular architectures, molecular receptors and molecular recognition, programed molecular systems, dynamic combinatorial libraries, coordination networks and functional supramolecular materials. We welcome submissions from all disciplines involved in this exciting and evolving area of science
Proceedings of the ECCOMAS Thematic Conference on Multibody Dynamics 2015
This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: ● Formulations and Numerical Methods ● Efficient Methods and Real-Time Applications ● Flexible Multibody Dynamics ● Contact Dynamics and Constraints ● Multiphysics and Coupled Problems ● Control and Optimization ● Software Development and Computer Technology ● Aerospace and Maritime Applications ● Biomechanics ● Railroad Vehicle Dynamics ● Road Vehicle Dynamics ● Robotics ● Benchmark ProblemsPostprint (published version
Multibody dynamics 2015
This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: Formulations and Numerical Methods, Efficient Methods and Real-Time Applications, Flexible Multibody Dynamics, Contact Dynamics and Constraints, Multiphysics and Coupled Problems, Control and Optimization, Software Development and Computer Technology, Aerospace and Maritime Applications, Biomechanics, Railroad Vehicle Dynamics, Road Vehicle Dynamics, Robotics, Benchmark Problems. The conference is organized by the Department of Mechanical Engineering of the Universitat Politècnica de Catalunya (UPC) in Barcelona. The organizers would like to thank the authors for submitting their contributions, the keynote lecturers for accepting the invitation and for the quality of their talks, the awards and scientific committees for their support to the organization of the conference, and finally the topic organizers for reviewing all extended abstracts and selecting the awards nominees.Postprint (published version
Safety and Reliability - Safe Societies in a Changing World
The contributions cover a wide range of methodologies and application areas for safety and reliability that contribute to safe societies in a changing world. These methodologies and applications include: - foundations of risk and reliability assessment and management
- mathematical methods in reliability and safety
- risk assessment
- risk management
- system reliability
- uncertainty analysis
- digitalization and big data
- prognostics and system health management
- occupational safety
- accident and incident modeling
- maintenance modeling and applications
- simulation for safety and reliability analysis
- dynamic risk and barrier management
- organizational factors and safety culture
- human factors and human reliability
- resilience engineering
- structural reliability
- natural hazards
- security
- economic analysis in risk managemen