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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.
91

Wavelength-dependent effects in optical-fibre waveguides

Hartog, Arthur H. January 1981 (has links)
No description available.
92

High capacity optical fibre transmission systems

Blank, Lutz Christian January 1992 (has links)
In this thesis a number of system design options are studied for the generation and processing of ultra—high speed optical data, based on the technique of Optical Time Division Multiplexing. The limits are investigated with regard to maximum unregenerated transmission distances for linear propagation over single mode fibre with large chromatic dispersion. Overall, the aim is to minimise the bandwidth requirements of electronic and opto—electronic system components for a given optical line capacity whilst at the same time maximising the chromatic dispersion limited propagation distances, thus exploring the potential for future system and network operating speeds of several tens of Gbit/s. A summary of standard system designs and their performance in terms of maximum system speed and dispersive fibre propagation provides an introduction into the field of high performance fibre optic data communication systems. Particular examples are used to introduce the device models subsequently employed in the analysis of new system configurations. This includes a description of the system performance measurements which are the basis for the performance analyses of the proposed ultra—high speed systems. In the field of fibre transmission research a variety of electrical interface and optical line signal formats are being investigated, each being appropriate for particular application areas and offering varying compromises between performance, complexity and user friendliness. In the context of this thesis the investigations are limited to high capacity time division multiplexed configurations, which represent a medium to longer term alternative as well as a complementary approach to the currently widely pursued system capacity upgrades by means of optical wavelength or frequency division multiplexing. Moreover, ultra—high speed time division multiplexed transmission is fundamentally compatible with WDM system operation, providing a future upgrade path for multi—wavelength systems being developed at the present time. The vehicle for these investigations is a set of computer models. Optical signal generation, pulse propagation in single—mode fibre, optical time domain processing, amplification and optical receiver detection are all included in the models to allow end—to—end system performance studies. Experimental results are presented at various stages to validate the models employed.
93

The analysis of inset dielectric guide and its application in leaky wave antennas

Ma, Lizhuang January 1989 (has links)
No description available.
94

A power based digital algorithm for the protection of embedded generators

Usta, Ö January 1992 (has links)
No description available.
95

A comprehensive method to estimate power system stability constraint costs

Hodgson, J. E. January 1997 (has links)
No description available.
96

Computer aided design of cable harnesses

Wu, Yunling January 1994 (has links)
No description available.
97

Application of wavelet transforms to vibration analysis for wood machining processes

Luo, Gaoyong January 2002 (has links)
No description available.
98

Modelling, simulation and control of photovoltaic converter systems

Gow, John A. January 1998 (has links)
The thesis follows the development of an advanced solar photovoltaic power conversion system from first principles. It is divided into five parts. The first section shows the development of a circuit-based simulation model of a photovoltaic (PV) cell within the 'SABER' simulator environment. Although simulation models for photovoltaic cells are available these are usually application specific, mathematically intensive and not suited to the development of power electronics. The model derived within the thesis is a circuit-based model that makes use of a series of current/voltage data sets taken from an actual cell in order to define the relationships between the cell double-exponential model parameters and the environmental parameters of temperature and irradiance. Resulting expressions define a 'black box' model, and the power electronics designer may simply specify values of temperature and irradiance to the model, and the simulated electrical connections to the cell provide the appropriate I/V characteristic. The second section deals with the development of a simulation model of an advanced PVaware DC-DC converter system. This differs from the conventional in that by using an embedded maximum power tracking system within a conventional linear feedback control arrangement it addresses the problem of loads which may not require the level of power available at the maximum power point, but is also able to drive loads which consistently require a maximum power feed such as a grid-coupled inverter. The third section details a low-power implementation of the above system in hardware. This shows the viability of the new, fast embedded maximum power tracking system and also the advantages of the system in terms of speed and response time over conventional systems. The fourth section builds upon the simulation model developed in the second section by adding an inverter allowing AC loads (including a utility) to be driven. The complete system is simulated and a set of results obtained showing that the system is a usable one. The final section describes the construction and analysis of a complete system in hardware (c. 500W) and identifies the suitability of the system to appropriate applications.
99

Improving In Vivo Two Photon Microscopy Without Adaptive Optics

Unknown Date (has links)
Two photon microscopy is one of the fastest growing methods of in-vivo imaging of the brain. It has the capability of imaging structures on the scale of 1μm. At this scale the wavelength of the imaging field (usually near infra-red), is comparable to the size of the structures being imaged, which makes the use of ray optics invalid. A better understanding is needed to predict the result of introducing different media into the light path. We use Wolf's integral, which is capable of fulfilling these needs without the shortcomings of ray optics. We predict the effects of aberrating media introduced into the light path like glass cover-slips and then correct the aberration using the same method. We also create a method to predict aberrations when the interfaces of the media in the light-path are not aligned with the propagation direction of the wavefront. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection
100

Trådlös överföring av styrsignaler / Wireless Control signals

Holmström, Magnus January 2002 (has links)
Anledningarna till att använda sig av en trådlös signalöverföring i en industri kan vara många, oftast handlar det om ställen där det är svårt eller omöjligt att ha en trådad förbindelse. I det här fallet är det en sedimenteringsbassäng där man tar hand om processvatten från industrin. Bassängen är utformad som en cylinder där vattnet rinner genom olika avdelningar för att minska innehållet av sediment. I bassängen cirkulerar en plattform med diverse omrörare och skrapor på. Eftersom denna del går runt hela tiden är det svårt att ha en fast förbindelse till de drifter som finns. Om man ska använda sig av en fast förbindelse måste kopplingen ske med släpringar, och denna typ av koppling kan bidra till en del problem vid signalöverföring i form av avbrott och störningar. Nu vill man prova alternativet att överföra alla styr och mätsignaler trådlöst. Trådlös signalöverföring är inget ovanligt, men det som är speciellt i det här fallet är att alla signaler ska gå trådlöst, även de som styr motordrifter. / There can be several reasons to use wireless signal transmission in a industry. Its often used in places where there is very hard ore impossible to use a cable. In this case it’s a basin that’s used for water cleaning that should be controlled wireless. The basin has a cylinder form and all the units that shouldbe controlled rotates in the basin. This makes it hard to use a cable. If a cable should be used the transmission between the rotating units and the control system needs to be connected with a drag contact that can lead to problems in the signal transfer. Now they want to try out the technology fore wireless transmission of the control signals. Today the basin is controlled by old electromechanically equipment that is mounted on the basin, but for better control and supervision of the basin its going to be controlled from a modern control system.

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