Дисертації з теми "High-local"
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1
Ågren, Magnus. "High-level modelling and local search /." Uppsala : Univ. : Dept. of Information Technology, Univ, 2005. http://www.it.uu.se/research/publications/lic/2005-003/.
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2
Stuart, John R. "High Definition (HD) Local Channel Project." Digital Commons at Loyola Marymount University and Loyola Law School, 2010. https://digitalcommons.lmu.edu/etd/441.
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3
Ågren, Magnus. "High-level modelling and local search." Licentiate thesis, Uppsala universitet, Avdelningen för datalogi, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-86352.
Повний текст джерелаАнотація:
Combinatorial optimisation problems are ubiquitous in our society and appear in such varied guises as DNA sequencing, scheduling, configuration, airline-crew and nurse rostering, combinatorial auctions, vehicle routing, and financial portfolio design. Their efficient solution is crucial to many people and has been the target for much research during the last decades. One successful area of research for solving such problems is constraint programming. Yet, current-generation constraint programming languages are considered by many, especially in industry, to be too low-level, difficult, and large. In this thesis, we argue that solver-independent, high-level relational constraint modelling leads to a simpler and smaller language, to more concise, intuitive, and analysable models, as well as to more efficient and effective model formulation, maintenance, reformulation, and verification. All this can be achieved without sacrificing the possibility of efficient solving, so that even time-pressed modellers can be well assisted. Towards this, we propose the ESRA relational constraint modelling language, showcase its elegance on some real-life problems, and outline a compilation philosophy for such languages. In order to compile high-level languages such as ESRA to current generation constraint programming languages, it is essential that as much support as possible is available in these languages. This is already the case in the constructive search area of constraint programming where, e.g., different kinds of domain variables, such as integer variables and set variables, and expressive global constraints are readily available. However, in the local search area of constraint programming, this is not yet the case and, until now, set variables were for example not available. This thesis introduces set variables and set constraints in the local search area of constraint programming and, by doing this, considerably improves the possibilities for using local search. This is true both for modelling and solving problems using constraint-based local search, as well as for using it as a possible target for the compilation of ESRA models. Indeed, many combinatorial optimisation problems have natural models based on set variables and set constraints, three of which are successfully solved in this thesis. When a new set constraint is introduced in local search, much effort must be spent on the design and implementation of an appropriate incremental penalty function for the constraint. This thesis introduces a scheme that, from a high-level description of a set constraint in existential second-order logic with counting, automatically synthesises an incremental penalty function for that constraint. The performance of this scheme is demonstrated by solving real-life instances of a financial portfolio design problem that seem unsolvable in reasonable time by constructive search.
4
Cripps, Martin David. "High efficiency, character-oriented, local area networks." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/47829.
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Clarin, Mattias. "High strength steel : local buckling and residual stresses." Licentiate thesis, Luleå, 2004. http://epubl.luth.se/1402-1757/2004/054.
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6
Peel, R. M. A. "High-throughput local area network access for INMOS transputers." Thesis, University of Surrey, 1995. http://epubs.surrey.ac.uk/770240/.
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This thesis presents the design of an Ethernet local-area network interface for embedded transputer systems. It is based upon parallel software which manages the TCP/IP family of protocols, passing packets between a single transputer, which connects to the network, and application processes which run on an arbitrary number of other transputers. The different layers of the protocol processing - Ethernet control, IP and TCP are all performed in separate parallel processes. Extra routing processors, arranged in a tree configuration, provide access to the lower IP and Ethernet layers from as many TCP and application processes as desired. Investigation of the processor utilisation and channel throughput of each of the parallel processes has led to the rejection of hardware-assistance in the form of a complex shared-memory, multi-processor architecture. Instead, a double pipeline of processes, running on a small pipeline of transputers, communicate exclusively using the transputers' serial links. This scheme is shown to provide good load balancing and to be a cost-effective way of exchanging traffic between a transputer application and a user process running on a high-performance workstation at data rates of over 950 kbytes/second - almost the entire available bandwidth of a 10 Mbit/sec Ethernet. All software is written in the occam programming language. As well as presenting the design of the protocol software, the thesis includes performance measurements and reports on two applications which were built upon the initial work. These are a networked implementation of the INMOS Iserver, which allows access to transputers from anywhere on the network, and an embedded instrumentation system which pre-processes data from an ion microbeam and passes part-analysed results to a conventional workstation for display, archiving and user control of the experiment.
7
Chang, Peter I. "High-speed atomic force microscopy through local raster scanning." Thesis, Boston University, 2012. https://hdl.handle.net/2144/31522.
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Thesis (Ph.D.)--Boston UniversityPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
Recent advances in high-speed atomic force microscopy (AFM), including new actuator design, advanced controller architecture and overall system optimization have made possible near video-rate imaging of biological samples. Despite this grand achievement, current state-of-the-art high-speed AFM systems still have their limitations, including a small image size and a limited choice of imaging modes. In addition, there are many interesting and important bio-related systems that have dynamics whose time scale is significantly faster than video rate. Thus there is a need to push imaging rates even higher for high-speed AFM systems. In this thesis, we discuss a novel tracking and imaging scheme known as the local raster scan (LRS) method, that can yield an order-of-magnitude improvement or more when imaging a particular class of samples. Local raster scanning utilizes data measured by the AFM system in real-time and steers the tip of the AFM to remain near the sample of interest at all times. LRS is designed for imaging biopolymers or other string-like samples and reduces the overall imaging time, not by increasing the speed of the instrument but by reducing the total sampling area. LRS is achieved by closing a high-level feedback loop around the AFM system. This thesis develops the LRS algorithm, beginning from design of the tip trajectory and moving through the detection schemes that measure the position of the sample in the scan. In addition, this thesis also provide an analysis of the errors of LRS that arise from the noisy measurements of AFM systems and discusses their influence on the performance of LRS. This framework provides a selection guide for choosing LRS parameters so as to maximize the tracking ability of the method. Both simulation and experimental results are included to demonstrate how the LRS performs in practice. These experiments are performed using a combined commercial AFM system together with a modified two-axis nano-positioning stage. The results illustrate improvements of up to an order of magnitude reduction in scan time, compared to the traditional raster scanning scheme with the same resolution and equivalent line rate.
2031-01-01
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Zahir, Humaira. "Performance of local aggregate in high friction surface treatment." Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/34562.
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Master of ScienceDepartment of Civil Engineering
Mustaque A. Hossain
Road surfaces may prematurely lose pavement friction due to polished aggregates on sharp horizontal curves, steep grades, or near intersections resulting in vehicle skidding. The problem gets exacerbated during wet weather. The Federal Highway Administration (FHWA) estimates that about 70% of wet pavement crashes can be prevented or minimized by improving pavement friction. High Friction Surface Treatment (HFST), a specially-designed thin surface application of hard aggregates and thermosetting resins like epoxy, has been proven to be an effective method to increase road surface friction. Calcined bauxite has been predominantly used in the United States as the hard aggregate in combination with an epoxy binder for HFST. However, this treatment is expensive since the calcined bauxite is imported. The objective of this study is to evaluate the performance of a local aggregate in HFST. Slab specimens of hot-mix asphalt (HMA) were compacted in the laboratory and treated with HFST systems incorporating both calcined bauxite and a local, hard aggregate, Picher Oklahoma flint aggregate. The treated HMA specimens were then tested with a Dynamic Friction Tester (DFT) and a Circular Track Meter (CTM) to determine the frictional coefficient and texture depth, respectively. Also, Hamburg Wheel Tracking Device Testing were conducted on these HFST systems to evaluate wearing resistance under repetitive wheel load. Field measurements of texture depths on HFST were also done. Statistical analysis was performed to compare the performance of high friction surfaces prepared with different aggregate epoxy combinations. The results show that flint aggregate can be a suitable substitute for the calcined bauxite in HFST. Field measurements also showed marked improvements in texture depth with HFST.
9
Klender, Stephanie. "Evaluation of Airborne Particles at a Local High School." University of Toledo Health Science Campus / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=mco1388746999.
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Averill, Linda. "A Local Area Network Implemented At Everett High School." NSUWorks, 1989. http://nsuworks.nova.edu/gscis_etd/394.
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The loss of library materials as well as of her departmental school materials has been a growing problem at Everett High School for the past several years. In recent years school budget cuts combined with a more mobile and transient student population has increased the awareness of the need for keeping better material accountability through efficient, accurate student obligation records. Decreased budgets, increased student loss of materials, and increased cost of replacement for those materials have focused administration attention on the need for an improved student obligation tracking system.
Everett High School covers a four block campus site located in the central area of the city of Everett, Washington, a community of approximately 60,000 citizens. In recent year’s school budget cuts and a more mobile, transient student population has caused this problem to take a higher priority in administration plans and goals.
Under the old system when a student withdrew, communication regarding return or replacement of materials broke down among departments. Often times students were expected to hand deliver their own obligation records for appropriate signatures before withdrawing. Under this system Obligation records were inaccurate, incomplete or lost. In several cases, students withdrew and their records transferred before an accurate accounting of their student obligations were recorded. Consequently, existing information that needed to be shared among various staff members was not properly processed in an accurate and timely manner resulting in: A. Library materials not returned. B. Textbooks not returned to teachers. c. Extracurricular equipment not returned (E .g. costumes for drama department). D. Fines for the above materials not collected.
Working in cooperation with Everett High administrators and staff, the investigator constructed a timeline of procedures and methods to install an information sharing system that would significantly reduce student materials loss. It was determined that this developmental project would cover a four year period from September, 1987, through June, 1991. From September, 1989, through June, 1991, the system would be fully functioning with constant monitoring and evaluation consistent with established goals and expectations.
Because accurate statistics could not be collected for unreturned materials from all Everett High departments, the investigator focused the statistical research on library materials unreturned or unreimbursed by withdrawn students for the period 1987-89, prior to installation of a LAN system. These figures provide the baseline data for the study. The LAN will be operational and the E.H.S. staff trained in its use by August, 1989. The LAN system will be fully functional from 1989-1991 and pertinent library data will be kept for this two year period for purposes of comparison with baseline data.
Upon evaluating the various constraints placed on the investigator by administrators regarding time, finances, staff and hardware, the investigator chose to combine hardware already in place at Everett High School with other compatible hardware to establish a new communication system. It was necessary to purchase additional Macintosh microcomputers, Apple printers and one laser printer.
Each microcomputer workstation was connected to the VAX through a twisted pair of telephone wires. This forced a star configuration with the VAX as the central server. The result was a local area network (LAN) in place at Everett High School.
The benefits to the Everett School District of using a LAN communication system will not be known until the project terminates in June, 1991. If the LAN system is found to be financially beneficial at Everett High the system could be expanded to include other schools in the district as well as the central office.
11
Sarrafan, Amir Mansour. "Transputer models for high-performance bridges in local area networks." Thesis, University of Kent, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278225.
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Zahoor, Mudasar. "Non-Local Damage Modeling of Rocks under the conditions of High Pressure and High Temperature (HPHT)." Research Showcase @ CMU, 2011. http://repository.cmu.edu/dissertations/555.
Повний текст джерелаАнотація:
This work is an attempt to develop a physically realistic model to understand the behavior and failure of rocks, especially under the extreme conditions of High Pressure and High Temperature (HPHT). A platform is laid in the preliminary work where 1D pure and ductile damage models are developed respectively. These models are based on an elasto-plastic model with an additional governing equation incorporated to facilitate the inclusion of damage. This additional governing equation is called the damage evolution equation. In the ductile damage model, it is assumed that the damage is driven and controlled by plasticity. The concepts developed in the preliminary work of 1D modeling are then taken into the study of 3D problems. The main problems studied are: the unconstrained uniaxial compression, the completely constrained uniaxial compression and the dynamic indentation problem. The dynamic indentation problem is the representation of an idealized rock drilling process. The results from the indentation problem are found to be in good qualitative agreement with the experimental results (Abd Al-Jalil, Y.Q 2006).
13
Lehto, Erik. "High Order Local Radial Basis Function Methods for Atmospheric Flow Simulations." Doctoral thesis, Uppsala universitet, Avdelningen för beräkningsvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-179194.
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Since the introduction of modern computers, numerical methods for atmospheric simulations have routinely been applied for weather prediction, and in the last fifty years, there has been a steady improvement in the accuracy of forecasts. Accurate numerical models of the atmosphere are also becoming more important as researchers rely on global climate simulations to assess and understand the impact of global warming. The choice of grid in a numerical model is an important design decision and no obvious optimal choice exists for computations in spherical geometry. Despite this disadvantage, grid-based methods are found in all current circulation models. A different approach to the issue of discretizing the surface of the sphere is given by meshless methods, of which radial basis function (RBF) methods are becoming prevalent. In this thesis, RBF methods for simulation of atmospheric flows are explored. Several techniques are introduced to increase the efficiency of the methods. By utilizing a novel algorithm for adaptively placing the node points, accuracy is shown to improve by over one order of magnitude for two relevant test problems. The computational cost can also be reduced by using a local finite difference-like RBF scheme. However, this requires a stabilization mechanism for the hyperbolic problems of interest here. A hyper-viscosity scheme is introduced to address this issue. Another stability issue arising from the ill-conditioning of the RBF basis for almost-flat basis functions is also discussed in the thesis, and two algorithms are proposed for dealing with this stability problem. The algorithms are specifically tailored for the task of creating finite difference weights using RBFs and are expected to overcome the issue of stationary error in local RBF collocation.
14
BryerJoyner, Susan Heller Scott D. "Secure local area network services for a high assurance multilevel network /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1999. http://handle.dtic.mil/100.2/ADA362547.
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Thesis (M.S. in Computer Science) Naval Postgraduate School, March 1999.Thesis advisor(s): Cynthia E. Irvine, James P. Anderson. "March 1999:. Includes bibliographical references (p. 213-215). Also available online.
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BryerJoyner, Susan, and Scott D. Heller. "Secure local area network services for a high assurance multilevel network." Thesis, Monterey, California. Naval Postgraduate School, 1999. http://hdl.handle.net/10945/13583.
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To reduce the cost and complexity of the current DoD information infrastructure, a Multilevel Secure (MLS) network solution eliminating hardware redundancies is required. Implementing a high assurance MLS LAN requires the ability to extend a trusted path over a TCP/IP network. No high assurance network trusted path mechanisms currently exist. We present a design and proof- of-concept implementation for a Secure LAN Server that provides the trusted path between a trusted computing base extension (TCBE) servicing a COTS PC and protocol servers executing at single sensitivity levels on the XTS-300. The trusted path establishes high assurance communications (over a TCP/IP network) between a TCBE and the Secure LAN Server. This trusted channel is used first for user authentication, then as a trusted relay between the protocol server and TCBE. All transmitted data passed over the LAN can be protected by encryption, providing assurance of integrity and confidentiality for the data. This thesis documents the implementation of a demonstration prototype Secure LAN Server using existing technology, including high assurance systems, COTS hardware, and COTS software, to provide access to multilevel data in a user-friendly environment. Our accomplishment is crucial to the development of a full scale MLS LAN.
16
Senger, Alexander. "A mobile atom interferometer for high-precision measurements of local gravity." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2012. http://dx.doi.org/10.18452/16449.
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Eine Reihe fundamentaler Problemstellungen setzt die genaue Kenntnis der Erdbeschleunigung g voraus, z.B. die Neudefinition des Kilogramms im laufenden Watt-Waage-Projekt. Des Weiteren sind Gravitationsmessungen ein herausragendes Werkzeug der geophysikalischen Forschung, machen sie doch Phänomene vom oberen Erdreich bis hinab in den Erdkern zugänglich. Für Absolutmessungen geeignete Quanten-Sensoren mit höchster Präzision sind deshalb Gegenstand aktueller Entwicklungen. Diese Arbeit beschreibt die Planung und Implementierung eines solchen Sensors, der für eine überlegene absolute Genauigkeit von fünf Teilen in 10^10, zu erreichen in Messungen von 24 h, ausgelegt ist. Ein Merkmal, das dieses Instrument vor früheren Entwicklungen auszeichnet, ist seine Mobilität, die Anwendungen im Feld sowie Vergleichsmessungen mit anderen Gravimetern ermöglicht. Die quantenmechanische Wellennatur von (Rubidium-) Atomen wird genutzt, um durch kohärente Teilung, Reflexion und Wiedervereinigung der sie konstituierenden Wellenpakete mit Hilfe von Lichtpulsen ein Materiewelleninterferometer darzustellen. Auf ein Ensemble lasergekühlter Atome im freien Fall angewandt, kann deren Empfindlichkeit auf Inertialkräfte genutzt werden, um hochsensible Messungen der auftretenden Beschleunigungen zu erreichen. Eine Messpräzision von 160 nm s^(-2) / sqrt(Hz) wird demonstriert, die ausreicht, um g in 15 h mit einer statistischen Ungewissheit von 0.8 nm s^(-2) zu bestimmen; dies ist um einen Faktor acht besser, als mit den besten klassischen Absolutgravimetern üblich. Ein Vergleich mit dem Deutschen Schweregrundnetz ergibt eine Abweichung von 260 nm s^(-2) bei einer Ungewissheit von 520 nm s^(-2) in den systematischen Einflüssen. Deren wahrscheinliche Ursachen sowie geeignete Gegenmaßnahmen werden identifiziert.Precise measurements of Earth''s gravitational acceleration $g$ are important for a range of fundamental problems - e.g. the Watt balance as an approach for a new definition of the kilogram - and a great tool to investigate geophysical phenomena reaching from the topmost layers of soil to the very core of our planet. Recently, research efforts have been made to develop dedicated quantum sensors capable of such measurements with very high precision and accuracy. This thesis describes the design and implementation of such a sensor, aiming at a superior accuracy of 0.5 ppb, resolvable in measurements of 24 h. A feature distinguishing this device from previous work is its mobility, allowing for comparison with other state-of-the-art instruments, and for applications in field use in various locations. Rubidium atoms are laser-cooled and launched on a free-fall trajectory. Exploiting the wave nature of quantum particles, coherent manipulation with light pulses is used to split, reflect and recombine the atoms'' wave-packets. The resulting matter-wave interferometer is highly susceptible to inertial forces and allows for sensitive measurements of accelerations. Inertial sensing with a precision of 160 nm s^(-2) / sqrt(Hz) was demonstrated, resulting in a measurement of g with a statistical uncertainty of 0.8 nm s^(-2) in 15 h, surpassing a conventional state-of-the-art absolute gravimeter by a factor of eight. Comparison with the German gravity reference net revealed a discrepancy of 260 nm s^(-2), well covered by the combined systematic uncertainties of 520 nm s^(-2). Likely causes for this deviation are identified and suitable countermeasures are proposed.
17
Fejes, Niklas. "High Performance Multi-Objective Voyage Planning Using Local Gradient-Free Methods." Thesis, Uppsala universitet, Avdelningen för beräkningsvetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-305582.
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A number of parallel gradient-free local optimization methods are investigated in application to problems of voyage planning for maritime ships. Two optimization algorithms are investigated, a parallel version of the Nelder-Mead Simplex method and the Subplex method with Nelder-Mead Simplex as its inner solver. Additionally, two new formulations of the optimization problem are suggested which together with an improved implementation of the objective function increases the overall performance of the model. Numerical results show the efficiency of these methods in comparison with the earlier introduced Grid search method and solvers from an open-source optimization library.
18
Samani, Nasab Mohammad. "Local probe of electronic states in high mobility quantum Hall samples." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/63080.
Повний текст джерелаАнотація:
The discovery of the integer quantum Hall effect (IQHE) and the fractional quantum Hall effect (FQHE) in a 2-dimensional electron gas (2 DEG ) have created a new and rich field in condensed matter physics in low dimensions. Almost 35 years after these discoveries, there are still several unanswered questions regarding the nature of various electronic phases formed in such systems. The 2 DEG in ultra-high mobility quantum well (QW) samples in large magnetic fields and millikelvin temperatures are studied in this thesis.
We developed a reproducible recipe for enhancing the quality of the very fragile FQHE states reliably, which can be used to reset an electrically shocked sample in-situ at low temperatures. We then developed a protocol for measuring the local electronic density on QW samples using a single-electron transistor (SET). We also developed a technique for modulating the temperature of the sample at about 10Hz by about 10mK. We used the electrometer and the fast temperature modulator to obtain a measure of changes in chemical potential as a function of temperature oscillations. This quantity can reveal the existence of an enhanced entropy in the state of the electrons.
We investigated theories that predict the non-Abelian state of matter, that follows neither Fermionic nor Bosonic statistics. Non-Abelian quasi-particles are expected to form as collective excitations in the fractional quantum Hall regime at filling factor ν=5/2. The experimental results were incompatible with the non-Abelian theory under investigation.
We also studied the nature of localization of electrons in the bulk of the sample when the system is in one of the incompressible states near an IQHE plateau. The noise characteristics detected by the ultra-sensitive charge sensor implanted on the surface of the sample revealed new behaviours not observed in the past. The results can be explained by telegraph noise arising from charge carriers jumping from one localized potential pocket to another, evolving into 1/f noise, as the filling factor shifts away from the centre of the integer state.Science, Faculty of
Physics and Astronomy, Department of
Graduate
19
Mutas, Sergej [Verfasser]. "Analysis of high-k materials with Local Electrode Atom Probe / Sergej Mutas." Aachen : Shaker, 2012. http://d-nb.info/1066198276/34.
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20
McCauley, Corey. "Forming Hartford Union High School's welding curriculum to meet local industries' needs." Online version, 2000. http://www.uwstout.edu/lib/thesis/2000/2000mccauleyc.pdf.
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21
Morapeli-Mphale, Matseliso. "Values, management and contributions of the high altitude wetlands to local livelihoods." Thesis, Bangor University, 2006. https://research.bangor.ac.uk/portal/en/theses/values-management-and-contributions-of-the-high-altitude-wetlands-to-local-livelihoods(b2ab20b1-9cfb-48bf-8048-7dab8ef132fa).html.
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The concerns regarding the high rates of species extinction in many ecosystems including wetlands seem to have prompted a hub of research aimed at re-designing and institutionalising approaches that would enable appropriate and sustainable management of the wetlands. Most of these approaches, however, have failed to integrate conservational and livelihood values of wild plants and have often resulted in disjointed solutions to resource management problems. In Lesotho the importance of the wetlands goes beyond their role as sources of livelihood for rural households. They are also vital hydrological reservoirs for most Southern Africa and key determinants of economic growth due to generation of hydroelectricity and revenue emanating from the sale of water to South Africa. However, attempts to avert species loss and the need to maintain revenue and other benefits have culminated in conservation measures polarized towards the eco-hydrological values as opposed to the livelihood values of these resources. Six villages in Pelaneng-Bokong area and twenty-nine wetland sites distributed across three management regimes and three grazing zones were studied in order to understand the complexity of the issues. This was attempted by determining floristic patterns of the key livelihood wetland plants, their harvesting and marketing patterns, the role of indigenous management systems as well as the contribution of wetland plant species to local livelihoods portfolios. The findings have shown that key livelihood wetland species were common and widespread in both the communal and RMA areas but poorly represented in Bokong Nature Reserve. Although there were no obvious destructive effects on harvested and traded plants, there were indigenous management practices in place geared towards forestalling over-exploitation and free-riding. The study also uncovered numerous tangible and intangible livelihood benefits from wetland plants, demonstrating that these plants make a difference to livelihood security of the rural households and local assets. The critical role of wetlands as sources of water for Lesotho and Southern African region is acknowledged as well as the need to harmonize hydrological and livelihood values.
22
Descoteaux, Maxime. "High angular resolution diffusion MRI : from local estimation to segmentation and tractography." Nice, 2008. http://www.theses.fr/2008NICE4000.
Повний текст джерелаАнотація:
La résolution actuelle des IRM pondérées en diffusion suggère qu'il y a entre un et deux tiers des voxels de la matière blanche qui contiennent plusieurs faisceaux de fibres qui se croisent. L'IRM par tenseur de diffusion (DTI) classique est intrinsèquement limitée à ces endroits par son hypothèse de base qu'un seul faisceau traverse chaque voxel de l'image. Le but de cette thèse est donc de développer des techniques d'IRM à haute résolution angulaire (HARDI) pour pouvoir retrouver une ou plusieurs fibres et surmonter aux limites DTI. L'imagerie par q-ball (QBI) est une technique récente qui permet d'estimer la distribution d'orientation des fibres (ODF). La technique de QBI ainsi que l'ODF de diffusion des fibres permettent de retrouver plusieurs directions de fibres en chaque voxel de l'image. Ceux-ci joueront donc un rôle important tout au long de ce document. Cette thèse propose plusieurs contributions originales. D'abord, nous développons l'estimation robuste du signal HARDI en utilisant une base modifiée d'harmoniques sphériques et un terme de régularisation. Ensuite, nous proposons la modélisation du coefficient de diffusion apparent (ADC) pour étudier les mesures d'anisotropie HARDI et faire la classification des voxels contenant une distribution isotrope, une distribution d'une seule population de fibres et une distribution de plusieurs faisceaux fibres. Nous proposons de plus, le développement d'une solution analytique pour estimer l'ODF de diffusion en QBI ainsi qu'un nouvel algorithme de segmentation de ces images d'ODF obtenues par le QBI. Nous présentons également le calcul de l'ODF de fibres avec une nouvelle méthode de déconvolution sphérique à partir des données QBI. Enfin, nous développons de nouveaux algorithmes de suivi de fibres (tracking) déterministes et probabilistes à partir de l'ODF du q-ball et l'ODF de fibres. Finalement, tous ces nouveaux algorithmes sont testés et appliqués sur des données HARDI simulées, sur un fantôme biologique et sur des données réelles de plusieurs sujets dans des régions complexes avec plusieurs faisceaux qui se croisent. Nos résultats illustrent clairement la valeur ajoutée de nos méthodes HARDI sur la plupart des méthodes courantes en DTI qui négligent ces faisceaux complexes, ce qui peut amener à une mauvaise analyse et interprétation de l'anatomie et des fonctions cérébralesAt the current resolution of diffusion-weighted (DW) magnetic resonance imaging (MRI), research groups agree that there are between one third to two thirds of imaging voxels in the human brain white matter that contain fiber crossing bundles. This thesis tackles the important problem of recovering fiber crossing bundles from DW-MRI measurements. The main goal is to overcome the limitations of diffusion tensor imaging (DTI). It is well-known that imaging voxels where there are multiple fiber crossings produce a non-Gaussian DW signal. This is precisely where DTI is limited due to the intrinsic Gaussian assumption of the technique. Hence, this thesis is dedicated to the development of local reconstruction methods, segmentation and tractography algorithms able to infer multiple fiber crossing from DW-MRI data. To do so, high angular resolution diffusion imaging (HARDI) is used to measure DW images along several directions. Q-ball imaging (QBI) is a recent such HARDI technique that reconstructs the diffusion orientation distribution function (ODF), a spherical function that has its maxima aligned with the underlying fiber directions at every voxel. QBI and the diffusion ODF will play a central role in this thesis. There are many original contributions in this thesis. First, we propose a robust estimation of the HARDI signal using a closed-form regularization algorithm based on the spherical harmonics. Then, we estimate the apparent coefficient coefficient (ADC) to study HARDI anisotropy measures and to discriminate voxels with underlying isotropic, single fiber and multiple fiber distributions. Next, we develop a linear, robust and analytical QBI solution using the spherical harmonic basis, which is used in a new statistical region-based active contour algorithm to segment important white matter fiber bundles. In addition, we develop a new spherical deconvolution sharpening method that transforms the diffusion q-ball ODF into a fiber ODF. Finally, we propose a new deterministic tractography algorithm and a new probabilistic tractography algorithm exploiting the full distribution of the fiber ODF. Overall, we show local reconstruction, segmentation and tracking results on complex fiber regions with known fiber crossing on simulated HARDI data, on a biological phantom and on multiple human brain datasets. Most current DTI based methods neglect these complex fibers, which might lead to wrong interpretations of the brain anatomy and functioning
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Ellis, Lawrence E. "Developing and implementing an environmental education course at a local high school." CSUSB ScholarWorks, 1991. https://scholarworks.lib.csusb.edu/etd-project/734.
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Franz, Dominik. "High harmonic generation in crystals assisted by local field enhancement in nanostructures." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS128/document.
Повний текст джерелаАнотація:
Le but de cette thèse est d’étudier le processus de la génération d’harmoniques d’ordre élevé (HHG, de l’anglais high-order harmonic generation) dans des solides et la possibilité d’augmenter l’efficacité de la génération en exploitant l’exaltation locale du champ incident dans des nanostructures. La HHG dans les gaz est connue depuis plusieurs décennies et a été étudiée en détails, par contre la HHG dans les solides a été démontrée pour la première fois en 2011. Différents processus comme les oscillations interbandes et intrabandes y jouent un rôle fondamental. Le processus exact est toujours en cours d’investigation et est discuté dans la communauté. Dans ce manuscrit, nous étudions la génération d’harmoniques dans différents cristaux, comme ZnO, CaCO₃ et CdWO₄. Nous confirmons que la HHG dépend de la longueur d’onde génératrice et de l’orientation cristalline. Outre les cristaux 3D nous étudions la HHG dans des matériaux 2D comme le graphène. Grâce à sa grande mobilité électronique et sa structure de bande spécifique la HHG dans graphène est plus efficaces que dans des cristaux 3D.Typiquement des intensités de 10¹² TW/cm² ou plus sont nécessaires pour susciter la HHG. Ces intensités élevées sont généralement atteintes par des méthodes comme l’amplification par dérive de fréquence qui génère des impulsions femtosecondes à des énergies µJ ou mJ. Grâce aux progrès récents des techniques de nanofabrication, il est possible d’exalter un champ électrique laser de plusieurs ordres de grandeurs dans des nanostructures. Alors que la HHG dans les gaz assistée par la plasmonique a été démontrée comme n’étant pas réalisable, des travaux récents démontrent l’amplification de la HHG dans des solides. Dans ce travail, nous étudions l’amplification de la HHG dans différentes configurations. D’abord, nous analysons différents types de nanostructures, à savoir des bow ties, des nano-trous, des réseaux et des résonateurs. Nous comparons ces structures suivant plusieurs critères tels que le volume d’exaltation et l’exaltation crête. Différentes longueurs d’onde et cristaux sont utilisés. Une large amplification de plusieurs ordres de grandeur est démontrée pour la troisième harmonique. En plus, nous discutons l’endommagement des nanostructures causé par l’irradiation laser. Des nanostructures semiconductrices confinant la lumière par guidage sub-longueur d’onde ont plusieurs avantages par rapport aux nanostructures métalliques. Des nanocones semiconducteurs, par exemple, présentent un grand volume d’amplification, supérieur de plusieurs ordres de grandeur à ce qui a été démontré récemment, et évitent la fusion observée dans des nanostructures métalliques. Nous présentons plusieurs itérations de l’expérience avec des nanocones de ZnO en améliorant le système de détection et la géométrie des nanocones entre chaque étape. Nous utilisons différents lasers et différentes géométries de nanocones. Nous avons observé les harmoniques d’un laser à 3.1 µm dans des nanocones de ZnO jusqu’à l’ordre 15. L’amplification de plusieurs ordres de grandeur d’harmoniques perturbatives et non perturbatives, générées à partir des impulsions d’un oscillateur nanojoule à une cadence MHz et une longueur d’onde de 2.1 µm, est démontrée pour la première fois jusqu’à H9. Le facteur d’amplification dépend de l’éclairement du faisceau pompe. Nous étudions également la forte amplification de la luminescence et proposons des méthodes pour séparer sa contribution de la contribution cohérente. En outre, nous démontrons plusieurs applications de la HHG dans les solides. Premièrement, nous proposons une nouvelle méthode pour déduire la distribution spatiale du champ électrique dans des nanostructures en analysant les dommages induits par laser. Deuxièmement, nous utilisons l’émission du nanocone, qui est cohérente spatialement, pour imager des objets avec une résolution à l’échelle nanométrique. Enfin, nous générons des harmoniques portant un moment orbital angulaire contrôléThe aim of this dissertation is to study the process of high-order harmonic generation (HHG) in solids and the possibility to amplify solid HHG by exploiting local field enhancements in nanostructures. While HHG in gases has been known for several decades and has been extensively studied, HHG in solids was first reported in 2011. Different processes such as interband and intraband oscillations were identified to play an important role in solid HHG. However, the process is still under investigation and debated in the community. Here, we study the generation of high harmonics in different crystals, such as ZnO, CaCO₃ and CdWO₄. We confirm that HHG depends on the driving wavelengths and on crystalline orientation. Beside 3D bulk crystals, we investigate HHG in 2D materials such as graphene. Due to its high electron mobility and its special band structure HHG in graphene is more efficient than in bulk crystals. Typically, intensities of 10¹² TW/cm² or more are needed to trigger HHG. The high intensity is reached by employing schemes like chirped pulse amplification which generates femtosecond pulses with µJ- or mJ-energies. Thanks to recent advances in nanofabrication techniques, nanostructures can enhance a laser electric field by several orders of magnitude. While plasmonically enhanced HHG in gases was shown not to be feasible, recent works reported on the amplification of HHG in solids. In this work, we explore the amplification of crystal HHG under various configurations. We first study different types of plasmonic nanostructures, namely bow ties, nanoholes, gratings and resonators. We compare them with respect to different parameters such as enhancement volume and peak enhancement. Different driving wavelengths and crystals are used. Strong amplification by several orders of magnitude is demonstrated for the third harmonic. Furthermore, we discuss radiation-induced damage of plasmonic nanostructures. Semiconductor nanostructures which confine light by subwavelength waveguiding have several advantages with respect to metallic nanostructures. Semiconductor nanocones for example exhibit a large amplification volume, several orders of magnitudes larger than previously reported and avoid melting observed in metallic nanostructures. We carry out several iterations of experiments with ZnO nanocones where the detection system and the nanocone geometry are improved in each cycle. We use different driving lasers and different optimized nanocone geometries. HHG in ZnO nanocones up to 15th order from a 3.1 µm driving laser is demonstrated. Amplification by several orders of magnitude of both perturbative and non-perturbative harmonics from nanojoule-oscillator pulses at MHz repetition rate and 2.1 µm wavelength is demonstrated, for the first time up to H9. The amplification factor depends on the pump intensity. We also explore the strong amplification of luminescence and propose ways to disentangle its contribution from the coherent one. Furthermore, we explore several applications of crystal HHG. First, we propose a new way to deduce the electric field spatial distribution in nanostructures by analyzing the radiation-induced damage. Secondly, we use the spatially coherent emission from the nanocone to image nanoscale objects with nanometer scale resolution. In addition, we generate solid harmonics that carry an orbital angular momentum
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Aziz, Farhan Muhammad. "Implementation and Analysis of Wireless Local Area Networks for High-Mobility Telematics." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/33505.
Повний текст джерелаАнотація:
Wireless networks provide communications to fixed, portable and mobile users and offer substantial flexibility to both end-users and service providers. Current cellular/PCS networks do not offer cost effective high data rate services for applications, such as, telematics, traffic surveillance and rescue operations. This research studies the feasibility and behavior of outdoor implementation of low-cost wireless LANs used for high mobility telematics and traffic surveillance. A multi-hop experimental wireless data network is designed and tested for this purpose. Outdoor field measurements show the wireless coverage and throughput patterns for static and mobile users. The results suggest that multi-hop wireless LANs can be used for high mobility applications if some protocols are improved.Master of Science
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Karam, Christina Maria. "Stochastic Bilateral Filter and Stochastic Non-local Means for High-dimensional Images." University of Dayton / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1429728892.
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Gamaleldin, Wael, and Najoua Maniar. "Textile Value Chains Competitive Advantages of Local Manufacturing in High-Cost Countries." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-24375.
Повний текст джерелаАнотація:
Background Globalization has forced textile firms to move their manufacturing to low-cost countries to reduce their prices. However, interest in local manufacturing has increased in recent years because of the trend in sustainability and changes in society’s ways of thinking, both of which can bring textile industry manufacturing back to high-cost countries. Purpose The purpose of this study is to formulate concepts and theories that can differentiate local manufacturers in high-cost countries from their competitors and identify the key competitive advantages that can lead to successful local production in high-cost countries. Methodology Two case studies were conducted of local textile manufacturers in Sweden in this study. Both companies’ value chain activities were examined to determine their competitive advantages. Empirical data were collected using semi-constructed interviews with key managers in both companies and were analysed using the thematic analysis method. Findings The textile industry in high-cost countries can create difference by considering competitive advantages, which are flexible and agile operations, development and innovation, sustainability, combining products and services, and uniqueness and differentiation. However, the competitive disadvantages of textile manufacturing in high-cost countries, which include scarcity of employees and high costs, should be considered as well.
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Jamil, Imad. "Improving spatial reuse in future dense high efficiency Wireless Local Area Networks." Thesis, Rennes, INSA, 2015. http://www.theses.fr/2015ISAR0033/document.
Повний текст джерелаАнотація:
Malgré leur réussite remarquable, les premières versions des normes de réseaux locaux sans fil IEEE 802.11, IEEE 802. 11 a/b/g WLAN, sont caractérisées par une efficacité spectrale faible qui est devenue insuffisante pour satisfaire la croissance explosive de la demande de capacité et de couverture. Grâce aux progrès considérables dans le domaine des communications sans fil et l'utilisation de la bande de fréquence autour de 5 gigahertz le standard IEEE 802.11n et plus récemment 1'IEEE 802.11ac ont amélioré les débits offerts par la couche physique. Cela été possible grâce principalement à l'introduction des techniques multi-antennaires (MIMO, pour Multiple-Input) et des techniques avancées de modulation et de codage. Aujourd'hui, deux décennies après sa première apparition, le Wi-Fi est présenté comme une technologie WLAN permettant des débits supérieurs à 1 gigabit par seconde. Cependant, dans la plupart des scénarios de déploiement du monde réel, il n'est pas possible d'atteindre la pleine capacité offerte par la couche physique. Avec la croissance rapide de la densité des déploiements des WLANs et l'énorme popularité des équipements Wi-Fi, la réutilisation spatiale doit être optimisée. D'autre part, des nouveaux cas d’utilisation sont prévus pour décharger les réseaux cellulaires et pour couvrir des grandes surfaces (stades, gares, etc.). Ces environnements de haute densité représentent un vrai défi pour les générations actuelles de Wi-Fi qui doivent offrir une meilleure qualité à moindre coût. C'est dans ce contexte que s’inscrit l'objectif de cette thèse qui porte sur l'amélioration de l'efficacité des protocoles de la couche MAC des réseaux WLAN de haute densité. Notamment, un des buts de cette thèse est de contribuer à la préparation de la prochaine génération du standard Wi-Fi : IEEE 802.11ax High Efficiency WLAN (HEW). Plutôt que de continuer à cibler l'augmentation des débits maximums théoriques, nous nous concentrons dans le contexte de HEW sur l'amélioration du débit réel des utilisateurs. Pour cela, on prend en compte tous les autres équipements associés à des WLANs voisins, qui essayent d'accéder au même canal de transmission d’une manière simultanée. Pour améliorer la performance du Wi-Fi dans ces environnements denses, nous proposons une adaptation dynamique du mécanisme de détection de signal. Comparé au contrôle de la puissance de transmission, le mécanisme proposé est plus incitatif parce que l'utilisateur concerné bénéficie directement de son application. Les résultats de nos simulations montrent des gains importants en termes de débit atteint dans les scénarios de haute densité. Ensuite, nous étudions l’impact de la nouvelle adaptation sur les mécanismes de sélection de débit actuellement utilisés. D'après les résultats obtenus, 1'adaptation proposée peut être appliquée sans avoir besoin de modifications substantielles des algorithmes de sélection de débit. Pour améliorer l'équité entre les différents utilisateurs, nous élaborons une nouvelle approche distribuée pour adapter conjointement le mécanisme de détection de signal et le contrôle de la puissance de transmission. Cette approche est évaluée ensuite dans différents scénarios de simulation de haute densité où elle prouve sa capacité à résoudre les problèmes d'équité en particulier en présence de nœuds d'anciennes générations dans le réseau, cela tout en améliorant le débit moyen d'un facteur 4 par rapport à la performance conventionnelle du standard. Enfin, nous concevons et mettons en œuvre une solution centralisée basée sur l'apprentissage à base de réseaux de neurones. Cette approche repose sur l'adaptation conjointe de puissance de transmission et du mécanisme de détection du signal. [...]Despite their remarkable success, the first widely spread versions of the Institute of Electrical and Electronics Engineers (IEEE) 802.11 Wireless Local Area Network (WLAN) standard, IEEE 802. 11 a/b/g, featured low spectral efficiencies that are becoming insufficient to satisfy the explosive growth in capacity and coverage demands. Thanks to the advances in the communication theory and the use of the 5 GHz frequency band, the IEEE 802.11n and recently the IEEE 802.1lac amendments improved the Physical Layer (PHY) data rates by introducing Multiple-Input Multiple Output (MIMO) techniques, higher Modulation and Coding Scheme (MCS), etc. Today, after almost two decades of its first appearance, Wi-Fi is presented as a gigabit wireless technology. However, the full potential of the latest PHY layer advances cannot be enabled in all real world deployment scenarios. With the rapidly increasing density of WLAN deployments and the huge popularity of Wi-Fi enabled devices, spatial reuse must be optimized. On another hand, the new challenging use case environments and the integration of mobile networks mainly for cellular offloading are limiting the opportunity of the current Wi-Fi generations to provide better quality at lower cost.In this thesis, we contribute to the current standardization efforts aiming to leverage the Wi-Fi efficiency in high density environments. At the time of writing this document, the IEEE 802.11ax Task Group (TG) is developing the specification for the High Efficiency WLAN (HEW) standard (next Wi-Fi evolution). Rather than continuing to target increased theoretical peak throughputs, we focus in the context of HEW on improving the throughput experienced by users in real life conditions where many other devices, belonging to neighboring overlapping networks, simultaneously contend to gain access. To enhance this performance, we propose a dynamic adaptation of the carrier sensing mechanism. Compare to controlling the transmission power, the proposed mechanism has more incentives because it benefits directly the concerned user. Extensive simulation results show impor1ant throughput gains in dense scenarios. Then, we study the impact of the new adaptation on the current rate control algorithms. We find that our adaptation mechanism operates efficiently without substantially modifying these algorithms that are widely used in today's operating WLANs. Furthermore, after analyzing the fairness performance of the proposed adaptation, we devise a new approach to jointly adapt the carrier sensing and the transmission power in order to preserve higher fairness degrees while improving the spatial reuse. This approach is evaluated in different dense deployment scenarios where it proves its capability to resolve the unfairness issues especially in the presence of legacy nodes in the network, while improving the achieved throughput by 4 times compared to the standard performance. Finally, we design and implement centralized learning-based solution that uses also an approach based on joint adaptation of transmission power and carrier sensing. This new solution takes benefit from the capability of artificial neural networks to model complex nonlinear functions to optimize the spatial reuse in dense WLANs while preserving fairness among contending nodes. The different contributions of this work have helped bring efficient solutions for future WiFi networks. We have presented these solutions to the IEEE 802.11ax TG where they were identified as important potential technical improvements for the next WLAN standard
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Haskel, Daniel. "Local structural studies of oriented high temperature superconducting cuprates by polarized XAFS spectroscopy /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/9712.
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Yackoski, Justin. "High performance medium access control protocols for decentralized wireless networks using local coordination." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 156 p, 2009. http://proquest.umi.com/pqdweb?did=1833647411&sid=1&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Hassan, Firas. "REAL-TIME EMBEDDED ALGORITHMS FOR LOCAL TONE MAPPING OF HIGH DYNAMIC RANGE IMAGES." University of Akron / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1195664951.
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Olive, Karl William. "Characteristics of Local Dual Credit Programs That Promote Sustained Enrollment and High School Achievement." TopSCHOLAR®, 2010. http://digitalcommons.wku.edu/theses/189.
Повний текст джерелаАнотація:
The intent of this study was to identify the features of local dual credit programs that promote high achievement and sustained enrollment. Ancillary outcomes of the study were to identify strengths and weaknesses of the programs as well as develop recommendations for the development and implementation of future dual credit programs in the area. The dual credit programs studied were offered by two secondary schools in conjunction with the local community and technical college. Information regarding the programs was collected via interviews from individuals at the secondary and postsecondary level who had substantial knowledge of the programs.
Overriding themes that emerged as a result of this study were the need to designate a single dual credit coordinator at both the college and the high schools to improve communication, the desire to increase participation in the existing programs while expanding the program to area schools that do not already participate in dual credit, and the need to maintain the quality and academic rigor of the courses.
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Schillo, Nicole [Verfasser]. "Local and global buckling of box columns made of high strength steel / Nicole Schillo." Aachen : Shaker, 2017. http://d-nb.info/1138177393/34.
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Huff, Richard F. "Achieving High Performance in Local Government: Linking Government Outcomes with Human Resource Management Practices." VCU Scholars Compass, 2007. http://hdl.handle.net/10156/2064.
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Di, Teodoro Enrico Maria <1985>. "Kinematics of local and high-z galaxies through 3D modeling of emission-line datacubes." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/7236/.
Повний текст джерелаАнотація:
The kinematics is a fundamental tool to infer the dynamical structure of galaxies and to understand their formation and evolution. Spectroscopic observations of gas emission lines are often used to derive rotation curves and velocity dispersions. It is however difficult to disentangle these two quantities in low spatial-resolution data because of beam smearing.
In this thesis, we present 3D-Barolo, a new software to derive the gas kinematics of disk galaxies from emission-line data-cubes. The code builds tilted-ring models in the 3D observational space and compares them with the actual data-cubes. 3D-Barolo works with data at a wide range of spatial resolutions without being affected by instrumental biases. We use 3D-Barolo to derive rotation curves and velocity dispersions of several galaxies in both the local and the high-redshift Universe. We run our code on HI observations of nearby galaxies and we compare our results with 2D traditional approaches. We show that a 3D approach to the derivation of the gas kinematics has to be preferred to a 2D approach whenever a galaxy is resolved with less than about 20 elements across the disk.
We moreover analyze a sample of galaxies at z~1, observed in the H-alpha line with the KMOS/VLT spectrograph. Our 3D modeling reveals that the kinematics of these high-z systems is comparable to that of local disk galaxies, with steeply-rising rotation curves followed by a flat part and H-alpha velocity dispersions of 15-40 km/s over the whole disks. This evidence suggests that disk galaxies were already fully settled about 7-8 billion years ago.
In summary, 3D-Barolo is a powerful and robust tool to separate physical and instrumental effects and to derive a reliable kinematics. The analysis of large samples of galaxies at different redshifts with 3D-Barolo will provide new insights on how galaxies assemble and evolve throughout cosmic time.
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Liu, Xuerong. "X-ray diffuse scattering studies of the local structural inhomogeneities in high temperature superconductors." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3339219.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--University of California, San Diego, 2009.Title from first page of PDF file (viewed February 6, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 126-131).
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Mascoop, Daniel R. "High-speed rail and local land development : case studies in London and Las Vegas." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113807.
Повний текст джерелаАнотація:
Thesis: M.C.P., Massachusetts Institute of Technology, Department of Urban Studies and Planning, 2017.Page 142 blank. Cataloged from PDF version of thesis.
Includes bibliographical references (pages 141-151).
This thesis explores the relationship between high-speed rail development, local rail station development and land development. The efficacy of a high-speed rail system depends, in part, upon rail stations' locations close to urban centers and integration into the broader transportation networks and urban realm. Through economies of agglomeration, high-speed rail can bring wider economic benefits to regions, cities and local areas. Transit-oriented development can be used as a strategy to capture these local-level benefits and also bring urban development to the highspeed rail system. In order to evaluate these relationships, this thesis examines two case studies. In the United Kingdom, the government chose St. Pancras Station as the London terminus for High-Speed 1, the first high-speed rail route in the UK. Although protected under historic landmark status, St. Pancras Station had been neglected for decades and required an E800 million refurbishment. This project also opened up new land, which currently is being developed as part of the 3 billion mixed-use project. Property values in the vicinity of the station have increased significantly, and this project has garnered wide acclaim for its architectural and place-making achievements. XpressWest, a private high-speed rail developer founded in 2005, is proposing to build and operate a high-speed rail line between Victorville, California, and Las Vegas, Nevada. XpressWest plans to compete mainly with driving, since this is the most common mode of transportation on this corridor. A benefit-cost analysis shows that the project likely will have net negative impacts when considering only transportation benefits, such as time-savings. Wider economic benefits, however, could be on the order of billions of dollars, and have the potential to exceed the project's costs. In conducting stakeholder analyses and in comparing these two case studies, this thesis determines that high-speed rail systems have the potential to generate a variety of local social and economic benefits, which are valued differently by different stakeholders. Through collaboration, these stakeholders may ensure that these local benefits are maximized. As long as these benefits hold value to the relevant stakeholders, there may be opportunities for local benefits to exceed the costs of infrastructure development.
by Daniel R. Mascoop.
M.C.P.
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Perret, Matias Nicholas. "Local optical phase detection probes with an application to a high speed boundary layer." Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/2129.
Повний текст джерелаАнотація:
This thesis presents the continued development of micro optical phase detection instrumentation capable of measuring void fraction, interfacial area density, interfacial velocity and bubble sizes and their application to measurements in a high speed boundary layer. The instrumentation consists of micro sized sapphire tipped probes tailored to measure in the two-phase flow of air bubbles in water. Probe tips with geometries intended to maximize field life while minimizing intrusiveness were designed, fabricated and characterized. The characterization revealed that the active region of a probe tip can go beyond the highly sensitive 45 degree tip. Controlling the active length of the tips can be achieved through a combination of taper angles and 45 degree tip size, with larger tips having shorter active lengths.
The full scale bubbly flow measurements were performed on a 6 m flat bottom survey boat. The aforementioned quantities were measured on bubbles naturally entrained at the bow of the boat. Probes were positioned at the bow of the boat, near the entrainment region and at the stern where the bubbles exit after having interacted with the high shear turbulent boundary layer. Experiments were conducted in fresh water, at the Coralville Lake, IA, and salt water, at the St. Andrews Bay and Gulf Coast near Panama City, FL. The results indicate that the bubbles interact significantly with the boundary layer. At low speeds, in fresh water, bubble accumulation and coalescence is evident by the presence of large bubbles at the stern. At high speeds, in both fresh and salt water, bubble breakup dominates and very small bubbles are produced near the hull of the boat. It was observed that salt water inhibits coalescence, even at low boat speeds. Void fraction was seen to increase with boat speeds above 10 knots and peaks near the wall. Bubble velocities show slip with the wall at all speeds and exhibit large RMS fluctuations, increasing near the wall.
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Lei, Xiangyu, and Jonas Persson. "Experimental Setup for Validating Simulated Local Structure Responses for High-speed Craft in Waves." Thesis, KTH, Marina system, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-215003.
Повний текст джерелаАнотація:
Using scantling codes such as DNV or ISO for designing high speed craft has been a routine for many constructors. However, the validity of these design methods are to be questioned, especially when dealing with modern material concepts and structural layouts, since they are based on data from ships designed in the 1960ies and 1970ies using semi-empirical methods containing substantial uncertainties and limitations. For direct assessment of loading conditions, modern methods such as CFD are appreciated. But they consume lots of time and resources in the design stage, which makes efficiency worse. A simulation approach making detailed assessment of loading conditions and structural behavior for high speed craft in waves has been developed at KTH Royal Institute of Technology in Sweden, with parts of the method still in need of further validation. In the here presented project an experimental setup has been developed for detailed validation of simulated local structural responses for high-speed craft in waves. The experimental setup consists of a model structure instrumented with strain gauges and pressure sensors that is integrated into a high speed craft model. Experimental data has been generated through experiments in regular and irregular waves in the towing tank at University of Naples “Federico II”. The model structure and generated data are concluded to be feasible for the intended validation.
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Yoon, Hyunsoo. "A study of high-performance packet switches for internetworking of integrated services local networks /." The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487596307356271.
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Ganti, Sudhakar N. M. "Access protocols and network architectures for very high-speed optical fiber local area networks." Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6917.
Повний текст джерелаАнотація:
The single mode optical fiber possesses an enormous bandwidth of more than 30 THz in the low-loss optical region of 1.3 $\mu$m and 1.5 $\mu$m. Through Wavelength Division Multiplexing (WDM), the optical fiber bandwidth can be divided into a set of high-speed channels, where each channnel is assigned its own unique wavelength. An M x M passive optical star coupler is a simple broadcast medium, in which light energy incident at any input is uniformly coupled (or distributed) to all the outputs. Thus, a passive star along with the WDM channels can be used to configure a Local Area Network (LAN). In this LAN, users require tunable devices to access a complete or a partial set of the WDM channels. Due to these multiple channels, many concurrent packet transmissions corresponding to different user pairs are possible and thus the total system throughput can be much higher than the data rates of each individual channel. To fairly arbitrate the data channels among the users, media access protocols are needed. Depending upon the number of data channels and the number of users, two possible situations arise. In the first case, the number of users is much larger than the number of data channels and in the second, the number of users equals to the the number of channels. In both cases, data channel contention may arise if multiple users access the same given channel and must be resolved. This thesis proposes media access protocols for passive optical star networks. All the proposed protocols are slotted in nature, i.e., the time axis on each channel is divided into slots. The well known Slotted-ALOHA and Reservation ALOHA protocols are extended to the multi channel network environment. The thesis also proposes switching protocols (equal number of channels and users), contention-based reservation protocols for this network architecture. To interconnect these star networks, a multi-control channel protocol is also proposed along with two interconnecting techniques. Since there are multiple data channels, the data packets on different channels may be destined to the same user. However, if the user is equipped with only one receiver, the user can receive only one packet and ignores others. This is called a 'receiver collision' and the thesis also studies the effect of these receiver collisions on the data channels. Two network architectures, one for a packet circulating ring network and the other for a circuit switched application are described. Finally, the thesis studies some implementation considerations for these protocols.
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Mysore, Paramesh Pragati. "Feasibility Study on Highly Slender Circular Concrete Filled Tubes Under Axial Compression." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/75045.
Повний текст джерелаАнотація:
Circular Concrete Filled Tubes are gaining importance in the construction industry due to their advantages insofar as economy and structural efficiency. Due to the recent developments in concrete and steel technology, the usage of high strength materials in these concrete filled tubes is increasing. The governing American specification (AISC 360-16) classifies these composite members as compact, non-compact and slender sections. The allowed section slenderness (ratio of diameter to thickness ratio) in each classification is related to the material properties (ratio of Young's modulus to yield strength ratio). AISC 360-16 is applicable for steels up to 75 ksi and concretes up to 10 ksi. These limits are lower than current available materials and restricts the usage of highly slender sections. As the strength of these tubes is dependent on local buckling, tests on many combinations of high strength steel and concrete are needed to extend these material limits.
This preliminary research work focuses on understanding the local buckling behavior of highly slender sections and the effect of concrete infill and its confinement. The research began by compiling a database that highlighted a gap on tests with highly slender sections and high strength materials. To address this issue, a pilot set of experimental tests were conducted on short circular concrete filled members. An analytical evaluation of these experimental results are performed using 3D finite element analysis models. The critical buckling load is determined using J2 deformation theory, which proves to give a good estimate when compared with the experimental results. The main objective of the work is to determine if a simplified test like the one used in this work could be used for the large experimental study that will be necessary to expend the material limits in AISC 360-16. The limited data developed in this study indicates that the test can provide satisfactory results with a few improvements and refinements.Master of Science
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Romberg, Stefan [Verfasser], and Rainer [Akademischer Betreuer] Lienhart. "Aggregating Local Features into Bundles for High-Precision Object Retrieval / Stefan Romberg. Betreuer: Rainer Lienhart." Augsburg : Universität Augsburg, 2014. http://d-nb.info/1077703732/34.
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Chen, Chuxing. "Local atmospheric electricity and its possible application in high-energy cosmic ray air shower detection." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184799.
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We have conducted an extensive experimental study on the subject of near ground atmospheric electricity. The main objective was to gain more understanding of this particular aspect of atmospheric phenomena, while testing the possible application to cosmic ray research. The results in atmospheric electricity show that there are certain patterns in ion grouping such as the size and lifetime. The average lifetime of ion group is 0.7 seconds and the average size is about 10 meters at our experimental site. Ultrahigh energy cosmic ray air showers should create sizable slow atmospheric electric pulses according to our theoretical calculations. Preliminary studies on air showers with total particle number N equal or greater than 10⁵ (10¹⁵ eV) have yielded strong evidence that slow atmospheric current pulses are associated with air showers. The theory and the experiment agree with each other fairly well when we average over large numbers of events. With our current experimental arrangement, when the air shower exceeds a certain size, the system response saturates. Therefore it is extremely desirable in future research that the counter array be designed for a much higher threshold level, since this prototype experiment indicates that interesting data would be obtained. Another reason for further experimental research being directed toward ultrahigh energy, e.g., N ≥ 10⁷ (10¹⁷ eV) and higher, is to establish a calibration of the slow atmospheric electric signals generated by cosmic rays as a function of primary cosmic ray energy and core location. This type of slow atmospheric electric signal, if fully understood and calibrated, offers a new and potentially less expensive technique to observe ultrahigh energy cosmic ray events, which hold some fundamental keys to the knowledge of the universe on a large scale.
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Dorr, Lisa Nancy 1960. "An in vivo study of variations in local power absorption in high temperature ultrasound hyperthermia." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/277277.
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The purpose of this research was to investigate temperature elevation variations caused by tissue location, tissue interfaces, and large blood vessels through a series of in vivo experiments using high power ultrasonic pulses. Results show that high temperature ultrasound hyperthermia does not suffer extensively from the tissue heterogeneities and even tissues within a few millimeters from an artery could be adequately exposed. Experimental results were compared with the temperature distributions predicted with computer simulations. The computer model studies indicate that matching simulated sound field distributions to the half power beam width measured in vivo provides an accurate estimate of experimental temperature distributions.
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Cao, Ning. "RECOVERING LOCAL NEURAL TRACT DIRECTIONS AND RECONSTRUCTING NEURAL PATHWAYS IN HIGH ANGULAR RESOLUTION DIFFUSION MRI." UKnowledge, 2013. http://uknowledge.uky.edu/cs_etds/13.
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Magnetic resonance imaging (MRI) is an imaging technique to visualize internal structures of the body. Diffusion MRI is an MRI modality that measures overall diffusion effect of molecules in vivo and non-invasively. Diffusion tensor imaging (DTI) is an extended technique of diffusion MRI. The major application of DTI is to measure the location, orientation and anisotropy of fiber tracts in white matter. It enables non-invasive investigation of major neural pathways of human brain, namely tractography. As spatial resolution of MRI is limited, it is possible that there are multiple fiber bundles within the same voxel. However, diffusion tensor model is only capable of resolving a single direction. The goal of this dissertation is to investigate complex anatomical structures using high angular resolution diffusion imaging (HARDI) data without any assumption on the parameters.
The dissertation starts with a study of the noise distribution of truncated MRI data. The noise is often not an issue in diffusion tensor model. However, in HARDI studies, with many more gradient directions being scanned, the number of repetitions of each gradient direction is often small to restrict total acquisition time, making signal-to-noise ratio (SNR) lower. Fitting complex diffusion models to data with reduced SNR is a major interest of this study. We focus on fitting diffusion models to data using maximum likelihood estimation (MLE) method, in which the noise distribution is used to maximize the likelihood. In addition to the parameters being estimated, we use likelihood values for model selection when multiple models are fit to the same data. The advantage of carrying out model selection after fitting the models is that both the quality of data and the quality of fitting results are taken into account. When it comes to tractography, we extend streamline method by using covariance of the estimated parameters to generate probabilistic tracts according to the uncertainty of local tract orientations.
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Masters, Daniel Charles. "Investigating the Local and High Redshift Universe With Deep Survey Data and Ground-Based Spectroscopy." Thesis, University of California, Riverside, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3618012.
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Large multiwavelength surveys are now driving the frontiers of astronomical research. I describe results from my work using data from two large astronomical surveys: the Cosmic Evolution Survey (COSMOS), which has obtained deep photometric and spectroscopic data on two square degrees of the sky using many of the most powerful telescopes in the world, and the WFC3 Infrared Spectroscopic Parallels (WISP) Survey, which uses the highly sensitive slitless spectroscopic capability of the Hubble Space Telescope Wide Field Camera 3 to detect star-forming galaxies over most of the universe's history. First I describe my work on the evolution of the high-redshift quasar luminosity function, an important observational quantity constraining the growth of the supermassive black holes in the early universe. I show that the number density of faint quasars declines rapidly above z ∼ 3. This result is discussed in the context of cosmic reionization and the coevolution of galaxies and their central black holes.
Next I present results of a multi-year campaign of near-infrared spectroscopy with FIRE, a world-class near-infrared spectrometer on the Magellan Baade 6.5 meter telescope in Chile, targeting emission-line galaxies at z ∼ 2 discovered with the Hubble Space Telescope. Our results showed that the typical emission-line galaxy at this redshift has low-metallicity, low dust obscuration, high ionization parameter, and little evidence for significant active galactic nucleus (AGN) contribution to the emission lines. We also find evidence that high redshift star-forming galaxies have enhanced nitrogen abundances. This result has interesting implications for the nature of the star formation in such galaxies – in particular, it could mean that a large fraction of such galaxies harbor substantial populations of Wolf-Rayet stars, which are massive, evolved stars ejecting large amounts of enriched matter into the interstellar medium.
Finally, I will discuss the discovery of three distant, ultracool brown dwarfs in the WISP survey. These objects, larger than massive planets but smaller than dwarf stars, are very difficult to detect, but their numbers and distribution in our galaxy have profound implications for our understanding of the formation of low-mass stars and planets. The brown dwarfs were found in the WFC3 grism spectroscopy, where they were identified through their strong atmospheric absorption features of water and methane. A systematic search for such objects in all WISP fields yielded three in total, allowing statistical inferences to be made regarding their distribution and number density in the Milky Way.
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Pike, Gary. "Understanding temporal and spatial temperature variation at the local scale in a high latitude environment." Thesis, University of Portsmouth, 2013. https://researchportal.port.ac.uk/portal/en/theses/understanding-temporal-and-spatial-temperature-variation-at-the-local-scale-in-a-high-latitude-environment(e17d7f10-06e8-4ad7-ad12-affdedac557d).html.
Повний текст джерелаАнотація:
The dearth of local scale data in remote high latitude areas means that regional scale data is commonly interpolated to fill the gap. These interpolations have limited accuracy due to the influence of complex topography and resultant decoupling of near-surface temperatures from regional free-air temperatures. Thus relatively little is known about how predicted regional temperature increases over the next century will likely influence local scale climates in subarctic Scandinavia. This thesis investigates local temperature variability in the incised valley area where the Kevo Subarctic Research Station (69°45'N, 27°01'E) is located. The main study area covered approximately 20km² encompassing the lake Kevojärvi and three incised valleys and an elevational range of 256m (74-330m a.s.l.). Near-surface temperature data were collected from a network of 60 temperature dataloggers for the period September 2007 to March 2012. NCEP/NCAR reanalysis data were used to reconstruct 6-hourly synoptic conditions for the study area. Lapse rates, principal component analysis and regression of surface temperatures on free-air temperatures were used to investigate present local temperature variability. The results were used to infer likely local scale temperature change assuming the strengthening westerlies and storm track predicted for the region. The data from the main network were also used to assess the representativeness of the Kevo Meteorological Station (established 1962). An additional network was set up to collect air and water temperature data from seven nearby lakes in order to validate air temperature estimations for the lakes, and to test a summer lake surface water temperature model based on air temperatures and theoretical solar radiation for remote lakes (June 2010 – September 2011). The results show a complex, highly variable temperature structure driven by the high latitude solar geometry, incised topography, variable land cover and synoptic conditions. Inversion conditions dominate temperature variability for most of the year, although with reduced influence during the polar day. Intense and persistent inversion events are a common feature of the winter months with gradients of +80°C/km not uncommon. The strongest inversion gradient was recorded at +92.4°C/km. Clear skies and low winds were the main controls of inversion formation during winter, but due to low temperatures (inhibiting convection) there was a weaker link between anticyclonic conditions and clear skies. Albedo induced steepening of lapse rates commonly gave day time lapse rates beyond -9.8°C/km (dry adiabatic) during March-May, with a peak of - 17.2°C/km measured. Diurnal temperature ranges for south facing low elevation sites were particularly large during the spring due to the daily inversion formation/destruction cycle (up to 30°C). During the ice-free period Kevojärvi had a significant influence on temperatures at low and mid elevations within the study area, resulting in a reversal of the usual day time strengthening of lapse rates. Due to its location in the valley bottom adjacent to Kevojärvi the meteorological station was not located in the most representative place in the local area (ranked 14/61), and certainly not representative of the wider area. The lake surface water temperature model showed good potential for future application. It was thought likely that predicted future synoptic changes in the region would act to inhibit inversion formation and intensity and so result in increased warming in the valley bottoms compared to the hilltops. Finally, due to the high frequency of inversion conditions and the resultant skew in temperature distributions, the reporting of lapse rates for areas such as this should be reported using median values, as mean values can be markedly different and therefore misleading.
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Pirouznia, Pouyan. "High cycle fatigue properties of stainless martensitic chromium steel springs." Thesis, KTH, Materialteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-103201.
Повний текст джерелаАнотація:
For many materials and components like in high speed trains and airplanes fatigue failures occur in the range of over 107 load cycles which is called the high cycle fatigue range. A modern version of the springs was invented which are applied in a certain application. Ultrasonic fatigue testing (20 kHz machine) was conducted for evaluating the steel of the springs. This research explores the fundamental understanding of high cycle fatigue testing of strip steel and assesses a stainless martensitic chromium steel at the high cycle fatigue range. Finite element modeling was conducted to gain knowledge about the effect of various parameters. Significant attention was devoted to the fatigue failure initiations by SEM/EDS. The work demonstrated that the method of investigation for high cycle fatigue test is reliable. Fatigue failure at this range was initiated by internal defects which all included non-metallic inclusion. A critical distance was defined Within the strip fatigue specimen where all the fatigue failure initiated. The 3D stress field in the specimen was determined by FEM modeling and the local applied stress at the whole of the flat part of specimen and critical distance was estimated. FEM was also employed to give additional information about the effect of parameters. It was established that damping had the largest influence. The local applied stress of the fatigue test was calculated by means of FEM and SEM analysis. It was used to adjust the S-N curve which resulted in 15% lower values than the nominal applied stress.
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Syu, Guo-Wei, and 徐國偉. "High-resolution ionospheric tomography using local pixel refinement." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/9u7a99.
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碩士國立中央大學
電機工程研究所
96
Abstract Resolution of the traditional ionospheric tomography is limited to the pixel size for discretizing the domain of interest. Specifically, with limited number of propagation paths between the ground stations and the satellite orbit, the reduction of the pixel size for improvement on the resolution often leads to artifacts in the results retrieved from the standard algorithms, such as the algebraic reconstruction technique (ART), the multiplicative algebraic reconstruction technique (MART), and the simultaneous iteration reconstruction technique (SIRT). This issue is mainly related to the ill-posed nature of the system equations from the ionospheric tomography. In this thesis, a local pixel-refinement technique is proposed for resolving this issue. The proposed technique exploits an inhomogeneous domain discretization. That is, in the domain of interest, the regions with high density gradient are dicretized using fine pixels, whereas the ones with low density gradient are dicretized using coarse pixels. With this discretiztion technique, the number of pixel is relatively reduced compared to the one form entire-domain fine discretization. With this technique, it is shown that the resolution of the reconstruction results is improved, and there is no observation of the aforementioned artifacts. The proposed technique is validated through the US-TEC data. Several events are used to demonstrate the effectiveness of the proposed technique. Indeed, with the proposed technique, the ionospheric irregularities, such as sporadic E layers and plasma bubbles, are identified in the reconstruction data using the standard ART, MART, and SIRT tomography algorithms. Indeed, the classical tomography algorithms with the proposed discretization technique are shown the effective tools for monitoring the ionospheric fine structures.