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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Space--Time Computation of Wind-Turbine Aerodynamics With Higher-Order Functions in Time

McIntyre, Spenser 16 September 2013 (has links)
This thesis is on the space--time variational multiscale (ST-VMS) computation of wind-turbine rotor and tower aerodynamics. The rotor geometry is that of the NREL 5MW offshore baseline wind turbine. We compute with a given wind speed and a specified rotor speed. The computation is challenging because of the large Reynolds numbers and rotating turbulent flows, and computing the correct torque requires an accurate and meticulous numerical approach. The presence of the tower increases the computational challenge because of the fast, rotational relative motion between the rotor and tower. The ST-VMS method is the residual-based VMS version of the Deforming-Spatial-Domain/Stabilized ST (DSD/SST) method, and is also called ``DSD/SST-VMST'' method (i.e., the version with the VMS turbulence model). In calculating the stabilization parameters embedded in the method, we are using a new element length definition for the diffusion-dominated limit. The DSD/SST method, which was introduced as a general-purpose moving-mesh method for computation of flows with moving interfaces, requires a mesh update method. Mesh update typically consists of moving the mesh for as long as possible and remeshing as needed. In the computations reported here, NURBS basis functions are used for the temporal representation of the rotor motion, enabling us to represent the circular paths associated with that motion exactly and specify a constant angular velocity corresponding to the invariant speeds along those paths. In addition, temporal NURBS basis functions are used in representation of the motion and deformation of the volume meshes computed and also in remeshing. We name this ``ST/NURBS Mesh Update Method (STNMUM).'' The STNMUM increases computational efficiency in terms of computer time and storage, and computational flexibility in terms of being able to change the time-step size of the computation. We use layers of thin elements near the blade surfaces, which undergo rigid-body motion with the rotor. We compare the results from computations with and without tower, and we also compare using NURBS and linear finite element basis functions in temporal representation of the mesh motion.
52

Trafikstyrning med variabel trafikutrustning : en behovsanalys för Vägverket Region Stockholm / Traffic control with variable traffic equipment : a requirement analysis for the Swedish National Road Administration

Thall, Anders January 2005 (has links)
When traffic in large cities increases, it becomes more vulnerable to disturbances such as accidents, stalled vehicles or construction; therefore, traffic jams are more likely to occur. For better control of the traffic at a disturbance the Swedish National Road Administration (SNRA) has traffic equipment which can be controlled from a command centre. This traffic equipment consists of gates and signs with variable messages. This report will discuss the system used for traffic control in Stockholm. It will present proposals designed to improve it. These proposals were prepared based on interviews with people from SNRA and their contractors as well as on comparisons with existing systems. The focus of this report is the handling of system alarms and graphical user interface. By implementing the proposals in this report, the following will be achieved: · More efficient alarmcontrol - the errors are discovered immediately or soon after they occur · Clearer information regarding alarms - the traffic operator receives better information about the error · Better control of the traffic equipment - the control will be easier and more flexible.
53

A Planning Model for Optimizing Locations of Changeable Message Signs

Henderson, Jeffrey January 2004 (has links)
Changeable Message Signs (CMS) are commonly utilized by transportation agencies to inform motorists of traffic, roadway, and environmental conditions. They may be used to provide information, such as delay and alternate route guidance, in the event of an incident, construction or a roadway closure. The effectiveness of CMS in managing freeway traffic, however, is a function of many factors including the number of CMS installations, the location of CMS, the messages displayed, varied traffic network characteristics, and drivers' response to incident conditions and CMS information. The objective of this thesis is to develop a CMS location planning model that can be used by transportation agencies to develop a CMS location plan that could achieve the largest long-term benefit to the system. This research is mainly motivated by the lack of systematic, robust and practical methods for locating CMS. State-of-practice methods rely mostly on the practitioner's experience and judgement. Other methods fail to incorporate reasonable driver behaviour models, consider time-varying demand, allow for computational efficiency on large networks, or consider the spatial variation of incidents on a traffic network. A new CMS location optimization model has been developed that is unique in both model realism and computational efficiency. The model incorporates several components to estimate incident delay, predict driver response, estimate network-wide benefit, and choose those CMS locations that would provide the most benefit. Deterministic queuing methods are used in conjunction with historic incident characteristics to approximate the delay impact of an incident with and without CMS. A discrete choice model is used to predict the rate at which drivers would switch from the incident route to a less congested alternative under CMS information. A network traffic assignment model is then incorporated in an attempt to estimate the resulting traffic induced by incidents. Genetic algorithms are utilized as an optimization technique to choose a set of CMS that would provide the most benefit. An extensive computational analysis was performed on both a hypothetical network and a segment of Highway 401 through Toronto. A sensitivity analysis was performed to test the model's response to parameter and data estimation errors. The model was found to be most sensitive to the diversion model parameters. The model produced reasonable results with locations selected upstream of major freeway interchange diversion points. Considering the additional components included in the proposed model, and its ability to consider more location schemes, the proposed model may be considered superior to previous CMS location models.
54

Insights into the distribution and mobility of metals in the sheeted dike complex formed at fast-spreading ridges (Pito Deep, EPR)

Zoeller, Khalhela 17 April 2014 (has links)
Hydrothermal fluid circulation is an important process in the formation and evolution of ocean crust. A tectonic window located at Pit Deep (NE corner Easter Microplate) provides an ideal location to examine a 3-dimensional view of ocean crust formed at the fast-spreading East Pacific Rise. This study focuses on the base metal (Cu, Ni, Mn, Co, Zn, and Pb) content of the bulk rock and mineral components in the sheeted dike complex. There is no observable trend of metal mobility with depth, geographic location, or dominant alteration phase. Secondary mineral analyses (using LA-ICP-MS) show that metals are redistributed throughout the sheeted dikes, entering into secondary sulphides, chlorite, and amphibole. Temperature and mineral stability is a primary control of metal mobility in these rocks. Due to highly variable metal concentrations and observed temperatures of alterations, the hydrothermal cell is suggested to be a continuously evolving system, and can cause the large variability observed in the metal distribution in the sheeted dikes. / Graduate / 0996 / 0411 / 0372
55

Hydrothermal Fe-Carbonate Alteration Associated with Volcanogenic Massive Sulfide (VMS) Deposits in Cycle IV of the Noranda Mining Camp, Rouyn-Noranda, Quebec

Wilson, Ryan 03 May 2012 (has links)
Massive sulfide deposits in the Noranda mining camp, northwestern Québec, are mainly associated with extensive footwall alteration defined by intense chloritization and sericitization. However, Fe-carbonate alteration also occurs in proximity to some deposits. To test the exploration significance of carbonate alteration in the camp, two areas of intense carbonate alteration were examined, around the small Delbridge deposit and near the new Pinkos occurrence in the Cyprus Rhyolite. Between 1969 and 1971, the Delbridge deposit produced 370,000 t of ore grading 9.6% Zn, 0.61% Cu, 110 g/t Ag, and 2.1 g/t Au. Recent drilling at the new Pinkos occurrence intersected 2.64 m of massive to semi-massive sulfides grading 8.1% Zn and 18.2 g/t Ag. Alteration mapping has shown that the distribution of Fe-carbonates can be used to identify vertically extensive zones of hydrothermal upflow at both properties. At Delbridge, intense Fe-carbonate alteration in brecciated rhyolite defines a pipe-like upflow zone that extends vertically for up to 300 m within the stratigraphic footwall of the massive sulfides and 100 m into the hanging wall. The location of known massive sulfide mineralization coincides with the intersection of the alteration pipe and a favorable horizon marked by the occurrence of fine-grained volcaniclastic rocks. At Pinkos, a similar zone of Fe-carbonate alteration occurs in outcrops of coherent rhyolite. Fe-carbonate alteration is most intensely developed along polygonal cooling fractures in massive rhyolite and decreases in intensity towards the centers of the columns. Fe-carbonate stringers and locally abundant matrix carbonate occur in fragmental rocks at the stratigraphic top of the coherent rhyolite flows and are most intense at the location of sulfide-bearing outcrops that mark the known mineralized horizon. Whereas Fe-carbonate alteration defines the central part of the hydrothermal upflow zones at both properties, disseminated pyrite occurs at the margins and is widespread outside the main upflow zones. This may indicate that Fe-carbonate in the main upflow zones formed at the expense of earlier disseminated sulfides. Replacement of pyrite by synvolcanic Fe-carbonate alteration at Delbridge and Pinkos can probably be attributed to a relatively high concentration of dissolved CO2, possibly of magmatic origin, in the main-stage ore-forming fluids.
56

Roles of factors in simulation of parking guidance and information systems

Peng, Wendi, Surveying & Spatial Information Systems, Faculty of Engineering, UNSW January 2008 (has links)
The Parking Guidance and Information (PGI) system is an important application of Intelligent Transport System (ITS), which has been shown to be an effect service for traffic information and parking management. The roadside Variable Message Sign (VMS) board has been the usual media for the publication of parking information in early PGI systems, and its performance over the years has been studied via simulations and questionnaire surveys. However, survey results show significant discrepancies across various traffic networks in different areas. More recently, parking information services have become available on other media such as mobile and in-vehicle devices. In contrast to VMS-based systems, PGI systems based on new media, especially the in-vehicle class of devices, have not been studied separately. This thesis aims to conduct research into the performance of PGI systems based on invehicle devices, by simulating and comparing a VMS-based PGI system with a Vehicle On-Board Device (VOBD)-based PGI system. A specially designed simulator utilising a routing algorithm known as the Ad hoc On-Demand Distance Vector (AODV) routing protocol in computer networks, has been created in MATLAB. The simulation minimises the influence of specific structures of traffic networks that may be found in some networks, but not others. This is done by simulating a grid-based road network where the capacities of parking stations and their geographic distribution are randomly allocated within specific zones, and the parking demand in each run of simulations is variable load. The results of simulations, including the information reliability, reduction of travel time, demand on on-street parking and the utilisation rates of parking stations, are analysed for multiple scenarios where the compliance rate, the information update policy and the strategy of human behaviour are varied. The analyses reveal a significant advantage of VOBD-based PGI systems over VMS-based PGI systems in terms of the quality of information and the reduction of travel time. At the same time, the analyses highlight the limitations of a PGI system when the demand and supply of parking stations is not appropriately balanced.
57

Hydrothermal Fe-Carbonate Alteration Associated with Volcanogenic Massive Sulfide (VMS) Deposits in Cycle IV of the Noranda Mining Camp, Rouyn-Noranda, Quebec

Wilson, Ryan January 2012 (has links)
Massive sulfide deposits in the Noranda mining camp, northwestern Québec, are mainly associated with extensive footwall alteration defined by intense chloritization and sericitization. However, Fe-carbonate alteration also occurs in proximity to some deposits. To test the exploration significance of carbonate alteration in the camp, two areas of intense carbonate alteration were examined, around the small Delbridge deposit and near the new Pinkos occurrence in the Cyprus Rhyolite. Between 1969 and 1971, the Delbridge deposit produced 370,000 t of ore grading 9.6% Zn, 0.61% Cu, 110 g/t Ag, and 2.1 g/t Au. Recent drilling at the new Pinkos occurrence intersected 2.64 m of massive to semi-massive sulfides grading 8.1% Zn and 18.2 g/t Ag. Alteration mapping has shown that the distribution of Fe-carbonates can be used to identify vertically extensive zones of hydrothermal upflow at both properties. At Delbridge, intense Fe-carbonate alteration in brecciated rhyolite defines a pipe-like upflow zone that extends vertically for up to 300 m within the stratigraphic footwall of the massive sulfides and 100 m into the hanging wall. The location of known massive sulfide mineralization coincides with the intersection of the alteration pipe and a favorable horizon marked by the occurrence of fine-grained volcaniclastic rocks. At Pinkos, a similar zone of Fe-carbonate alteration occurs in outcrops of coherent rhyolite. Fe-carbonate alteration is most intensely developed along polygonal cooling fractures in massive rhyolite and decreases in intensity towards the centers of the columns. Fe-carbonate stringers and locally abundant matrix carbonate occur in fragmental rocks at the stratigraphic top of the coherent rhyolite flows and are most intense at the location of sulfide-bearing outcrops that mark the known mineralized horizon. Whereas Fe-carbonate alteration defines the central part of the hydrothermal upflow zones at both properties, disseminated pyrite occurs at the margins and is widespread outside the main upflow zones. This may indicate that Fe-carbonate in the main upflow zones formed at the expense of earlier disseminated sulfides. Replacement of pyrite by synvolcanic Fe-carbonate alteration at Delbridge and Pinkos can probably be attributed to a relatively high concentration of dissolved CO2, possibly of magmatic origin, in the main-stage ore-forming fluids.
58

Elektronisk krigföring mot sensorer i varnar- och motverkanssystem / Electronic warfare against sensors used in active protection systems

Nilsson, Jesper January 2021 (has links)
This report on the subject of Systems Science for Defence and Security, aims to study the possibility for electronic warfare (EW) against the radar in active protection system (APS) on ground combat vehicles. The goal of the EW is to ensure effect of current anti-tank systems against an enemy equipped with APS. Given that the radar is susceptible to jamming, (1) Which opportunities would an EW-system used in conjunction with an anti-tank system, bestow on a successful engagement? (2) Which effect could jamming of an APS result in, and what type of jamming would yield this desired effect?  The result concludes that an APS would increase the statistical number of needed anti-tank projectiles in a given engagement with a combat vehicle by 700 %, from a stated number of five to six to 35–43. This increase shows how the efficiency of an APS is linked to needed anti-tank systems for the same effect, but also the potential gain from employing an EW-system. Studying the use of stand-off jamming, where the jamming is produced in a separate system, there’s no need for new development of weapons systems or munitions. The jamming should employ a technique of combined range and velocity deception (CRV) or noise to successfully lower the efficiency of the APS. Angle deception have arisen as a desirable technique, with promise of an increase of survivability of EW- and anti-tank units, and further studies are therefore interest. / Detta självständiga arbete på grundnivå inom ämnet försvarssystem behandlar möjligheter till aktiv radarstörning av varnar- och motverkanssystem (VMS), i syfte att erhålla verkan med befintliga burna pansarvärnssystem mot stridsfordon. Givet att aktiv radarstörning kan användas mot ett varnar- och motverkanssystem med förstörande motmedel; (1)Vilka möjligheter till verkan ger ett telekrigsystem med aktiv radarstörning i kombination med ett pansarvärnssystem?(2)Vilken typ av aktiv radarstörning är lämplig och vilken effekt på det störda systemet kan förväntas?  Arbetet visar på effekten VMS statistiskt har på duellen mellan stridsfordon och pansarvärnssystem. Beräkningarna utgår ifrån påståendet att det krävs fem till sex pansarvärnprojektiler för nedkämpning av ett stridsfordon, vilket ökar till 35-43st då fordonet utrustas med VMS. Ökningen på cirka 700% visar dels på hur effektiviteten hos VMS höjer antalet erfordrade pansarvärnsvapen för att nå samma effekt, men även den potentiella vinningen att sänka effektiviteten genom telekrig. Arbetet studerade nyttjandet av bakgrundsstörning, då genereringen av störsignalen sker i ett separat telekrigsystem, vilket inte kräver utveckling av nya vapensystem eller ammunition. För utformning av störningen faller en kombinerad hastighet och avstånds vilseledning (CRV) eller brus lämplig och anses sänka effektiviteten hos VMS. Vinkelavhakning har i arbetet visat sig medföra stora förtjänster för ökad överlevnad hos telekrig/pansarvärnsenheter och vidare forskning är därför intressant.
59

Cost-efficient resource allocation for green distributed clouds / Allocation de ressources pour un cloud green et distribué

Ahvar, Ehsan 09 January 2017 (has links)
L'objectif de cette thèse est de présenter de nouveaux algorithmes de placement de machines virtuelles (VMs) à fin d’optimiser le coût et les émissions de carbone dans les Clouds distribués. La thèse se concentre d’abord sur la rentabilité des Clouds distribués, et développe ensuite les raisons d’optimiser les coûts ainsi que les émissions de carbone. La thèse comprend deux principales parties: la première propose, développe et évalue les algorithmes de placement statiques de VMs (où un premier placement d'une VM détient pendant toute la durée de vie de la VM). La deuxième partie propose des algorithmes de placement dynamiques de VMs où le placement initial de VM peut changer dynamiquement (par exemple, grâce à la migration de VMs et à leur consolidation). Cette thèse comprend cinq contributions. La première contribution est une étude de l'état de l'art sur la répartition des coûts et des émissions de carbone dans les environnements de clouds distribués. La deuxième contribution propose une méthode d'allocation des ressources, appelée NACER, pour les clouds distribués. L'objectif est de minimiser le coût de communication du réseau pour exécuter une tâche dans un cloud distribué. La troisième contribution propose une méthode de placement VM (appelée NACEV) pour les clouds distribués. NACEV est une version étendue de NACER. Tandis que NACER considère seulement le coût de communication parmi les DCs, NACEV optimise en même temps les coûts de communication et de calcul. Il propose également un algorithme de cartographie pour placer des machines virtuelles sur des machines physiques (PM). La quatrième contribution présente une méthode de placement VM efficace en termes de coûts et de carbone (appelée CACEV) pour les clouds distribués verts. CACEV est une version étendue de NACEV. En plus de la rentabilité, CACEV considère l'efficacité des émissions de carbone pour les clouds distribués. Pour obtenir une meilleure performance, la cinquième contribution propose une méthode dynamique de placement VM (D-CACEV) pour les clouds distribués. D-CACEV est une version étendue de notre travail précédent, CACEV, avec des chiffres supplémentaires, une description et également des mécanismes de migration de VM en direct. Nous montrons que notre mécanisme conjoint de réallocation-placement de VM peut constamment optimiser à la fois le coût et l'émission de carbone dans un cloud distribué / Virtual machine (VM) placement (i.e., resource allocation) method has a direct effect on both cost and carbon emission. Considering the geographic distribution of data centers (DCs), there are a variety of resources, energy prices and carbon emission rates to consider in a distributed cloud, which makes the placement of VMs for cost and carbon efficiency even more critical and complex than in centralized clouds. The goal of this thesis is to present new VM placement algorithms to optimize cost and carbon emission in a distributed cloud. It first focuses on cost efficiency in distributed clouds and, then, extends the goal to optimization of both cost and carbon emission at the same time. Thesis includes two main parts. The first part of thesis proposes, develops and evaluates static VM placement algorithms to reach the mentioned goal where an initial placement of a VM holds throughout the lifetime of the VM. The second part proposes dynamic VM placement algorithms where the initial placement of VMs is allowed to change (e.g., through VM migration and consolidation). The first contribution is a survey of the state of the art on cost and carbon emission resource allocation in distributed cloud environments. The second contribution targets the challenge of optimizing inter-DC communication cost for large-scale tasks and proposes a Network-Aware Cost-Efficient Resource allocation method, called NACER, for distributed clouds. The goal is to minimize the network communication cost of running a task in a distributed cloud by selecting the DCs to provision the VMs in such a way that the total network distance (hop count or any reasonable measure) among the selected DCs is minimized. The third contribution proposes a Network-Aware Cost Efficient VM Placement method (called NACEV) for Distributed Clouds. NACEV is an extended version of NACER. While NACER only considers inter-DC communication cost, NACEV optimizes both communication and computing cost at the same time and also proposes a mapping algorithm to place VMs on Physical Machines (PMs) inside of the selected DCs. NACEV also considers some aspects such as heterogeneity of VMs, PMs and switches, variety of energy prices, multiple paths between PMs, effects of workload on cost (energy consumption) of cloud devices (i.e., switches and PMs) and also heterogeneity of energy model of cloud elements. The forth contribution presents a Cost and Carbon Emission-Efficient VM Placement Method (called CACEV) for green distributed clouds. CACEV is an extended version of NACEV. In addition to cost efficiency, CACEV considers carbon emission efficiency and green distributed clouds. It is a VM placement algorithm for joint optimization of computing and network resources, which also considers price, location and carbon emission rate of resources. It also, unlike previous contributions of thesis, considers IaaS Service Level Agreement (SLA) violation in the system model. To get a better performance, the fifth contribution proposes a dynamic Cost and Carbon Emission-Efficient VM Placement method (D-CACEV) for green distributed clouds. D-CACEV is an extended version of our previous work, CACEV, with additional figures, description and also live VM migration mechanisms. We show that our joint VM placement-reallocation mechanism can constantly optimize both cost and carbon emission at the same time in a distributed cloud
60

MIGRATING FROM A VAX/VMS TO AN INTEL/WINDOWS-NT BASED GROUND STATION

Penna, Sergio D., Rios, Domingos B. 10 1900 (has links)
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Upgrading or replacing production systems is always a very resource-consuming task, in particular if the systems being replaced are quite specialized, such as those serving any Flight Test Ground Station. In the recent past a large number of Ground Station systems were based in Digital’s VAX/VMS architecture. The computer industry then expanded very fast and by 1990 realtime PCM data processing systems totally dependent on hardware and software designed for IBM-PC compatible micro-computers were becoming available. A complete system replacement in a typical Ground Station can take from one to several years to become a reality. It depends on how complex the original system is, how complex the resulting system needs to be, how much resources are available to support the operation, how soon the organization needs it, etc. This paper intends to review the main concerns encountered during the replacement of a typical VAX/VMS-based by an Intel-Windows NT-based Ground Station. It covers the transition from original requirements to totally new requirements, from mini-computers to micro-computers, from DMA to high-speed LAN data transfers, while conserving some key architectural features. This 8-month development effort will expand EMBRAER’s capability in acquiring, processing and archiving PCM data in the next few years at a lower cost, while preserving compatibility with old legacy flight test data.

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