Spelling suggestions: "subject:"level crossing"" "subject:"level grossing""
31 |
Factors shaping pedestrians’ unsafe behaviour at actively protected level crossings / Facteurs influençant le comportement non sécuritaire des piétons aux passages à niveau actifsStefanova, Teodora 10 September 2015 (has links)
Le nombre des collisions avec des piétons aux passages à niveau restant stable dans les dernières années, c’est un problème majeur au niveau international. Suite à la revue étendue de la littérature, des lacunes scientifiques importantes liées à l’étude du comportement du piéton ont été identifiées. L’objectif principal de ce programme de recherche était de contribuer à mieux comprendre le comportement du piéton aux passages à niveau actifs en Australie, où malgré la mise en place des protections renforcées pour les piétons, le nombre de collisions reste plus important que sur les autres types de passages à niveau. Trois études ont été réalisées pour répondre aux trois buts de recherche que nous nous proposons d'examiner dans le cadre de ce programme. La première étape de recherche qui est exploratoire a été réalisée dans le cadre des études 1 et 2 dont les conclusions ont permis d'identifier les facteurs influençant la prise de décision aux passages à niveau. A la fin de cette étape un nouveau modèle systémique a été développé pour servir d’instrument à l’analyse du comportement du piéton, influencé par des facteurs de tous les niveaux du système. Dans la deuxième étape empirique de recherche, nous avons mené l’étude 3 pour examiner l’impact de facteurs clés sur les comportements à risque dans différentes situations à risque de traversée des piétons. L’articulation des trois études est une illustration des bénéfices associés avec l’utilisation à la fois des méthodes systémiques et traditionnelles, résultant des contributions théoriques et pratiques importantes. / Level crossing collisions with pedestrians are a major issue worldwide and in Australia, where their number remains stable in recent years. An extended review of the literature highlighted a number of important scientific gaps in current knowledge on the factors shaping specifically pedestrian behaviour. The main objective of this research program was to contribute to the better understanding of pedestrian behaviour at active level crossings in Austalia, where a larger number of collisions are reported despite the reinforced safety measures in place. Three research aims were formulated and supported the development of three studies.Study 1 and 2 were part of the first explorative stage of research and informed on the main factors shaping crossing decisions of pedestrians. At the end of this stage a new systems-based framework was developed as a tool for the analysis of pedestrian behaviour as influenced by factors across all system levels. Study 3, part of the empirical stage of research, examined in depth the influence of key precursors of unsafe behaviour across different crossing situations. The articulation of the three studies demonstrates the benefits of using systems-based and traditional individual-centred methods in a complementary manner resulting in important theoretical and practical contributions.
|
32 |
Estatisticas de ordem superior para canais de desvanecimento Weibull e Nakagami-m / Higher order statistics for Nakagami-m and Weibull fading channelsCosta, Daniel Benevides da 28 April 2006 (has links)
Orientador: Michel Daoud Yacoub / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-06T06:51:34Z (GMT). No. of bitstreams: 1
Costa_DanielBenevidesda_M.pdf: 1293492 bytes, checksum: 3aa8e540fd57db56b2ee4469c60307be (MD5)
Previous issue date: 2006 / Resumo: Esta dissertação provê uma análise das estatísticas de ordem superior para canais de desvanecimento WeibuII e Nakagami-m. Considerando canais de desvanecimento WeibulI, devido à ausência de um modelo físico para tais canais, estatísticas conjuntas de duas variáveis WeibuII correlacionadas foram obtidas em forma fechada e em função de parâmetros físicos bem conhecidos. Outra estatística encontrada foi a taxa de cruzamento de nível e a duração média de desvanecimento usando diversidade com dois ramos para canais WeibuII correlacionados, desbalanceados e não-idênticos. Além disso, uma caracterização do comportamento do processo de fase e de sua derivada temporal para sinais WeibuII foi realizada. Analisando canais de desvanecimento Nakagami-m, uma expressão simples e em forma fechada para a taxa de cruzamento de fase generalizada foi obtida. Resultados de simulação completamente validaram a formulação proposta. Além disso, novas estatísticas em forma fechada para a envoltória, para as componentes em fase e em quadratura, para a fase e para suas respectivas derivadas temporais foram obtidas / Abstract: This dissertation provides an analysis of the higher order statistics for WeibuII and Nakagami-m fading channels. Conceming WeibuII fading channels, due to the absence of a fading model related of such channels, joint statistics for two correlated WeibuII variates were obtained in cIosed-form and in terms of welI-known physical parameters. Other statistics found were the levei crossing rate and the average fade duration for unbalanced, non-identical, correlated WeibuII channels operating over two branches of diversity. Furthermore, a characterization of the behaviour of the phase process and its time derivative for WeibuII signals was accomplish. Conceming Nakagami-m fading channeIs, a simple and cIosed-form expression for the generalized phase crossing rate was obtained. Results of simulation thoroughly validated the formulation proposed. Moreover, new cIosed-form statistics for the envelope, for the in-phase and quadrature components, for the phase and its respective time derivative were derived. / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica
|
33 |
Einstellung von PI-Reglern bei Send-on-Delta-AbtastungHensel, Burkhard 08 December 2017 (has links) (PDF)
Energieeffizienz hat in Forschung und Alltag eine zentrale Bedeutung. Arbeiten verschiedene elektronische Geräte zusammen, um gemeinsam eine Regelungsaufgabe zu lösen, müssen sie miteinander kommunizieren. Ein Beispiel aus dem Alltag sind Funk-Raumtemperaturregler, bei denen ein batteriebetriebener Temperatursensor und ein Heizungsaktor (Stellantrieb am Heizungsventil) über drahtlose Kommunikation zusammenarbeiten. Diese Kommunikation benötigt oft mehr Energie als der Betrieb der eigentlichen (elektronischen) Funktionalität der Teilsysteme.
Energieeffizienter als die in Regelkreisen übliche periodische (äquidistante) Abtastung ist – durch eine Verringerung der Nachrichtenrate – eine ereignisbasierte Abtastung. Send-on-Delta-Abtastung ist die am weitesten verbreitete Art der ereignisbasierten Abtastung. Dabei wird der Wert der Regelgröße (im Beispiel die Raumtemperatur) nicht in konstanten Zeitintervallen übertragen, sondern nur dann, wenn er sich um einen bestimmten Betrag geändert hat.
Der mit einem Anteil von über 90 % im Praxiseinsatz am weitesten verbreitete Reglertyp ist der PID-Regler, wobei die meisten als „PID-Regler“ bezeichneten Regler aus verschiedenen Gründen keinen D-Anteil (Differential-Anteil) verwenden und daher als „PI-Regler“ bezeichnet werden können. Die vorliegende Arbeit verfolgt das Ziel, systematisch zu untersuchen, wie man PI-Regler einstellen sollte, um neben dem Erreichen einer hohen Regelgüte auch die Vorteile der Send-on-Delta-Abtastung bezüglich der Netzlastreduktion und Energieeffizienz bestmöglich auszunutzen. Die „Gewichtung“ dieser sich teilweise widersprechenden Kriterien ist anwendungsspezifisch einstellbar. / Energy efficiency is very important both in science and everyday life. If different electronic devices work together, for example for solving a control task together, they have to communicate with each other. An everyday life example are room temperature controllers using radio communication between a battery-powered temperature sensor and a heating actuator. This communication often needs more energy than the operation of the actual (electronic) functionality of the components.
More energy-efficient than the commonly used periodic sampling is event-based sampling, due to the reduction of the message rate. Send-on-delta sampling is the most widely-known kind of event-based sampling. In that case, the value of the controlled variable (e.g. the room temperature) is not transmitted equidistantly but only when it has changed by a specific amount.
The most successful controller in practice is the PID controller. The most so-called “PID controllers” do not use the D part (differential action) for several reasons and can therefore be called “PI controllers”. This work analyses systematically how the parameters of a PI controller should be tuned to reach besides a high control quality also a good exploitation of the advantages of send-on-delta sampling regarding network load reduction and energy efficiency. The “weighting” of these partially contradicting criteria is application specifically adjustable.
|
34 |
Úprava mimoúrovňové křižovatky Hradecká x Sportovní x Palackého / Modifying interchanges Hradecka x Sports x PalackyChlíbek, David January 2015 (has links)
Thesis subject is a project documentation as a proposal of reconstruction of level crossing in Hradecká street to elevated crossing. Proposal is based on research of traffic intensity and consequential assessment of traffic capacity. Another thesis subject is a verification of potencial proposal of elevated crossing in Sportovní street and Hradecká street, which exists only in one way in present. This proposal is only indicative and can be used for next stage of project documentation. Proposal of crossing in Hradecká and Palackého třída includes design of beam of elevated crossing and design of cover crossing. Elevated crossing of Sportovní and Hradecká is designed as a beam of crossing, which runs on bridge construction of concrete.
|
35 |
Návrh rekonstrukce železničních stanic Šternberk a Bohuňovice / Design of reconstruction of railway stations Šternberk nad BohuňoviceŠatánek, Jan January 2017 (has links)
The design of reconstruction of railway stations Šternberk and Bohuňovice comprises the proposal to increase the line speed of the main track to the maximum possible value, the design of station tracks and reconstruction of railway switches and crossings, the design of the new platforms, which implements the requirements for people with reduced mobility and the design of new drainage system. Next, the design of reconstruction comprises the design of the railway superstructure and substructure and the design of railway level crossings.
|
36 |
Dolování víceúrovňových sekvenčních vzorů / Mining Multi-Level Sequential PatternsŠebek, Michal January 2017 (has links)
Dolování sekvenčních vzorů je důležitá oblast získávání znalostí z databází. Stále více průmyslových a obchodních aplikací uchovává data mající povahu sekvencí, kdy je dáno pořadí jednotlivých transakcí. Toho může být využito například při analýze po sobě jdoucích nákupů zákazníků. Tato práce se zabývá využitím hierarchického uspořádání položek při dolování sekvenčních vzorů. V rámci práce jsou řešeny dvě základní oblasti - dolování víceúrovňových sekvenčních vzorů s křížením a bez křížení úrovní hierarchií. Dolovací úlohy pro obě oblasti jsou v práci formalizovány a následně navrženy algoritmy hGSP a MLSP pro jejich řešení. Experimentálně bylo ověřeno, že především algoritmus MLSP dosahuje výborných výkonnostních vlastností a stability. Význam nově získaných vzorů je ukázán na dolování reálných produkčních dat.
|
37 |
Link Stability Analysis of Wireless Sensor Networks Over the Ocean SurfaceShahanaghi, Alireza 03 September 2021 (has links)
Ocean-surface Wireless Sensor Networks (WSN) are essential in various thalassic applications,
such as maritime communication, ocean monitoring, seawater examination, pollution
detection, etc. Formed by simple structured sensor nodes, ocean-surface WSN can improve
the data transmission rate, enhance the monitoring resolution, expand the geographical
coverage, extend the observation period, and lower the cost compared to the vessel-based
monitoring approaches. Despite the importance and the broad applications of ocean-surface
WSNs, little is known about the stability of the wireless links among the sensors. Especially,
research suffers from the lack of an accurate model that describes the environmnetal
effects, including the ocean surface movements and the wind speed on the link stability. The
inappropriate understanding of link stability can result in network protocols that are not
robust to environmental interruptions. Such a shortcoming decreases the network reliability
and degrades the accuracy of the network planning. To compensate for this shortcoming, in
this dissertation, we provide a thorough analysis on the stability of the wireless links over
the ocean. In particular, we investigate and capture the effects of ocean waves on the link
stability through the following steps. First, we use the linear wave theory and obtain a novel
stochastic model of Line-of-Sight (LoS) links over the ocean based on the realistic behavior
of ocean waves. Second, we present and prove an important theorem on the level-crossing
of Wide Sense Stationary (WSS) random processes, and combine that with our stochastic
model of LoS links to study two important indicators of link stability, i.e., the blockage probability
and the blockage and connectivity periods. The former indicates the probability that
a LoS link is blocked by the ocean waves while the latter determines the duration of on/off
periods of the LoS links over the ocean. The aforementioned stability parameters directly
affect different stages of network design, such as choosing the antenna height, planning the
sensors' deployment distances, determining the packet length, designing the retransmission
and scheduling strategies in the Medium Access Control (MAC) protocols and transport
layer protocols, selecting the fragmentation threshold in Internet Protocol (IP), etc., which
will be discussed in the respective chapters. In the last part of our dissertation, we investigate
the problem of linear prediction of ocean waves, which has special importance in the
design of ocean-surface WSNs. In this regard, we first introduce a low-complexity metric
for effectiveness of k-step-ahead linear prediction, which we refer to as efficiency curve. The
significance of efficiency curve becomes evident when we decide upon the number of previous
samples in the linear prediction model, and determine the extent to which the predictor
forecasts the future. After efficiency curve, we formulate an adaptive Wiener filter to predict
the ocean waves and adapt the prediction model according to the environmental changes. / Doctor of Philosophy / Covering almost three quarters of the earth and supplying half of its oxygen, oceans are
vital to the support of life on our planet. It is important to continuously monitor different
parts of the ocean environment for tracking climate changes, detecting pollution, etc. However,
the existing monitoring approaches have serious weaknesses, which prevent us from
constantly monitoring the state of ocean, and drastically limit the geographical coverage.
For instance, the traditional ocean monitoring system using oceanographic research vessels
is time-consuming and expensive. Besides, it has low resolution in time and space, which
poses serious challenges to oceanographers by providing under-sampled records of the ocean.
To compensate for these defects, one of the promising alternatives is to employ Wireless
Sensor Networks (WSN) which has many advantages, such as real-time access to data for
a longer period of time and a larger geographical coverage of the ocean, higher resolution
of monitoring, faster processing of collected data and instantaneous transmission to onshore
monitoring centers. With the benefit of simple structure sensor nodes, ocean-surface WSNs
can also decrease the cost by at least one order of magnitude compared to the conventional
approaches. Despite the advantages that ocean surface WSN have over traditional ocean
monitoring methods, ocean surface WSN research suffers from the lack of an accurate model
that describes the stability of wireless links among sensor nodes. While some of the existing
literature has developed accurate models of the electromagnetic wave propagation over the
ocean surface, they have failed to consider the environmental effects, such as ocean waves on
the stability of the links. To fill this void, in this dissertation, we investigate ocean surface
waves' effects on the Line-of-Sight (LoS) link between the sensors in an ocean-surface WSN.
Specifically, we derive the blockage probability, and the blockage and connectivity periods of
LoS links between a transmitter and receiver pair due to wave movements. In addition to the
link stability analysis, we dedicate the last part of this dissertation to look into the problem
of linear prediction of ocean waves, which has special importance in the design process of
ocean-surface WSNs. In this regard, we present a low-complexity metric for effectiveness of
k-step-ahead linear prediction, and formulate an adaptive Wiener filter to predict the ocean
waves and adapt the prediction model according to the environmental changes.
|
38 |
Wireless Link Quality Modelling and Mobility Management for Cellular NetworksNguyen, Van Minh 20 June 2011 (has links) (PDF)
La qualité de communication dans un réseau sans fil est déterminée par la qualité du signal, et plus précisément par le rapport signal à interférence et bruit. Cela pousse chaque récepteur à se connecter à l'émetteur qui lui donne la meilleure qualité du signal. Nous utilisons la géométrie stochastique et la théorie des extrêmes pour obtenir la distribution de la meilleure qualité du signal, ainsi que celles de interférence et du maximum des puissances reçues. Nous mettons en évidence comment la singularité de la fonction d'affaiblissement modifie leurs comportements. Nous nous intéressons ensuite au comportement temporel des signaux radios en étudiant le franchissement de seuils par un processus stationnaire X (t). Nous démontrons que l'intervalle de temps que X (t) passe au-dessus d'un seuil γ → −∞ suit une distribution exponentielle, et obtenons 'egalement des r'esultats caract'erisant des franchissements par X (t) de plusieurs seuils adjacents. Ces r'esultats sont ensuite appliqu'es 'a la gestion de mobilit'e dans les r'eseaux cellulaires. Notre travail se concentre sur la fonction de 'handover measurement'. Nous identifions la meilleure cellule voisine lors d'un handover. Cette fonction joue un rôle central sur expérience perçue par l'utilisateur. Mais elle demande une coopération entre divers mécanismes de contrôle et reste une question difficile. Nous traitons ce problème en proposant des approches analytiques pour les réseaux émergents de types macro et pico cellulaires, ainsi qu'une approche d'auto- optimisation pour les listes de voisinage utilisées dans les réseaux cellulaires actuels.
|
39 |
Zvýšení bezpečnosti a plynulosti dopravy na I/43 Černá Hora - Sebranice / Safety and fluency increasing - road I/43 Černá Hora - SebraniceBažant, Petr January 2015 (has links)
A part of the road I/43 in the section between Černá Hora and Sebranice is the subject of diploma thesis. The output of thesis is to identify problematic parts of the safety and fluency of traffic and to propose appropriate measures. The road I/43 is very problematic and discussed of these aspects. Becouse of the character and the results of traffic accidents is called Highway of death. The thesis contains proposals of structural modification in selected problematic sections. These structural modifications are intended to increase the safety of traffic, but in order to limit of flow of traffic. Depending on the long-delayed contruction of expressway R43 is in order to make quick and effective increase the safety and the fluency of traffic counting with traffic intensity in the full range.
|
40 |
Einstellung von PI-Reglern bei Send-on-Delta-Abtastung: Regelkreisoptimierung unter Berücksichtigung von Energieeffizienz, Netzlast und RegelgüteHensel, Burkhard 25 October 2017 (has links)
Energieeffizienz hat in Forschung und Alltag eine zentrale Bedeutung. Arbeiten verschiedene elektronische Geräte zusammen, um gemeinsam eine Regelungsaufgabe zu lösen, müssen sie miteinander kommunizieren. Ein Beispiel aus dem Alltag sind Funk-Raumtemperaturregler, bei denen ein batteriebetriebener Temperatursensor und ein Heizungsaktor (Stellantrieb am Heizungsventil) über drahtlose Kommunikation zusammenarbeiten. Diese Kommunikation benötigt oft mehr Energie als der Betrieb der eigentlichen (elektronischen) Funktionalität der Teilsysteme.
Energieeffizienter als die in Regelkreisen übliche periodische (äquidistante) Abtastung ist – durch eine Verringerung der Nachrichtenrate – eine ereignisbasierte Abtastung. Send-on-Delta-Abtastung ist die am weitesten verbreitete Art der ereignisbasierten Abtastung. Dabei wird der Wert der Regelgröße (im Beispiel die Raumtemperatur) nicht in konstanten Zeitintervallen übertragen, sondern nur dann, wenn er sich um einen bestimmten Betrag geändert hat.
Der mit einem Anteil von über 90 % im Praxiseinsatz am weitesten verbreitete Reglertyp ist der PID-Regler, wobei die meisten als „PID-Regler“ bezeichneten Regler aus verschiedenen Gründen keinen D-Anteil (Differential-Anteil) verwenden und daher als „PI-Regler“ bezeichnet werden können. Die vorliegende Arbeit verfolgt das Ziel, systematisch zu untersuchen, wie man PI-Regler einstellen sollte, um neben dem Erreichen einer hohen Regelgüte auch die Vorteile der Send-on-Delta-Abtastung bezüglich der Netzlastreduktion und Energieeffizienz bestmöglich auszunutzen. Die „Gewichtung“ dieser sich teilweise widersprechenden Kriterien ist anwendungsspezifisch einstellbar. / Energy efficiency is very important both in science and everyday life. If different electronic devices work together, for example for solving a control task together, they have to communicate with each other. An everyday life example are room temperature controllers using radio communication between a battery-powered temperature sensor and a heating actuator. This communication often needs more energy than the operation of the actual (electronic) functionality of the components.
More energy-efficient than the commonly used periodic sampling is event-based sampling, due to the reduction of the message rate. Send-on-delta sampling is the most widely-known kind of event-based sampling. In that case, the value of the controlled variable (e.g. the room temperature) is not transmitted equidistantly but only when it has changed by a specific amount.
The most successful controller in practice is the PID controller. The most so-called “PID controllers” do not use the D part (differential action) for several reasons and can therefore be called “PI controllers”. This work analyses systematically how the parameters of a PI controller should be tuned to reach besides a high control quality also a good exploitation of the advantages of send-on-delta sampling regarding network load reduction and energy efficiency. The “weighting” of these partially contradicting criteria is application specifically adjustable.
|
Page generated in 0.1389 seconds