Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 250 for “"stepped"”.
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Advancements of Stepped Planing Hulls
The straight line calm water performance of stepped planing hulls has been studied experimentally, by prediction method, and numerically. A model test was conducted to provide a systematic understanding of the effects that displacement and step location have on the performance of a stepped planing …
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Velocity compensation in stepped frequency rada
… used constant frequency radar waveforms, the stepped-frequency waveform can achieve high range resolution while still retaining the advantages of lower instantaneous receiver bandwidth and lower analog-to-digital sampling rate. However, the relative radial motion between the target and the …
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Stepped care for chronic fatigue syndrome
Contains fulltext : 117687.pdf (Publisher’s version ) (Open Access)
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Flow and sediment movement in stepped channels
Laboratory tests were undertaken to establish the formative mechanism for steps and pools in steep mountain streams. They indicated that the formation of steps and pools is associated with high intensity, low return interval events and the processes of armouring/paving and antidune formation. Lower …
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Optimized Harmonic Stepped-Waveform for Multilevel Inverter
… described. The concept of the Optimized Harmonic Stepped-Waveform (OHSW) technique for a multilevel inverter is presented. By applying this concept, specific harmonics can be eliminated, and the output voltage THD can be improved. A procedure to achieve the appropriate switching angles of the OHSW …
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Variable permittivity dielectric material loaded stepped-horn antenna
Stepped-horn antenna loaded with dielectric material of variable permittivity is proposed to improve radiation characteristics and/or to increase the electrical dimensions of the radiating structure compared to unloaded empty one. A hybrid numerical technique is used to analyze such an antenna. The …
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Simulation of axisymmetric stepped surfaces with a facet
A crystal lattice with a small miscut from the plane of symmetry has a surface which consists of a series of atomic height steps separated by terraces. If the surface of this crystal is not in equilibrium with the surrounding medium, then its evolution is strongly mediated by the presence of these …
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Torsional stress concentration factor for hollow stepped shafts
… concentration factor was evaluated for a hollow stepped shaft with variable wall thickness and two fillet sizes. Electric strain gages of the SR-4 type were employed to measure strains in the fillet section. Values of the stress concentration factor were determined with the ratio of inside to …
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Scanning tunneling microscopy: application to stepped surfaces and magnetite
Contains fulltext : mmubn000001_161992064.pdf (Publisher’s version ) (Open Access)
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Numerical Modeling Of Lightning Initiation And Stepped Leader Propagation
… of cloud-to-ground (CG) lightning flashes and stepped leaders that folloIBPs were modeled using multi-sensor electric field change (E-change) measurements. This study uses data collected with a network of ten E-change sensors located at Kennedy Space Center. Locations (x,y,z,t) of IBPs were …
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Aspects of stepped-frequency processing for low-frequency SAR systems
… (VHF/UHF-band) SAR processing: 1. The use of stepped-frequency waveforms to increase the total radar bandwidth, thereby increasing the range resolution, and 2. Radio frequency interference (RFI) suppression. A stepped-frequency system owes its wide bandwidth to the transmission of a group of …
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A 500kHz-5MHz CW stepped frequency borehole tomographic imaging system
This dissertation involves a study of Cross-Borehole Tomography. The mathematical physical models of the Radon Transform are reviewed. The entire Cross-Borehole Tomographic process is simulated, based on these physical models of the Radon Transform. The system specifications for the final design …
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Stepped-frequency pulse train waveforms for improved radar range resolution
… modulated chirp signal is approximated using two stepped-frequency pulse train waveforms, a continuous wave pulse train and a linear frequency modulated pulse train. The continuous wave pulse train consists of a series of single frequency pulses, each at a different frequency. It is found to be …
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Improved Design Method for Cambered Stepped Hulls with High Deadrise
Eugene Clement created a design method for swept-back cambered step hulls with deadrise. The cambered step is designed to carry 90% of the planing vessels weight with the remaining 10% being support by a stern mounted hydrofoil. The method requires multiple design iterations in order to achieve an …
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RF hardware design of a stepped frequency continuous wave ground penetrating radar
Research into stepped frequency continuous wave ground penetrating radar (SFCW GPR) at UCT has been carried out since 1990. A first generation system comprising of Hewlett-Packard test equipment controlled by a PC was assembled. Cavity-backed log spiral antennas were designed and built by the …
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