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.
Results
Showing 1 to 20 of 29 for “"Doppler effect"”.
-
OFDM for Underwater Acoustic Communication
… multipath, frequency selectivity, noise, and the Doppler effect — than the over-the-air radio frequency channel. In this work a time warp based technique which can be used to model time-varying wideband Doppler shifts (as seen in an UWA channel) in MATLAB is proposed. A corresponding procedure to …
-
Advanced MIMO-OFDM technique for future high speed braodband wireless communications. A study of OFDM design, using wavelet transform, fractional fourier transform, fast fourier transform, doppler effect, space-time coding for multiple input, multiple output wireless communications systems
… frequencies, typical of LTE standard, with Doppler effects. It was found that, during high mobile speed, it is better to transmit OFDM signals using lower operating frequencies. The information theory for the 2-transmit antenna OSTBC does not support higher order implementation of …
-
Automated detection of a crossing contact based on its Doppler shift
… to specific target types. By contrast, the Doppler effect is readily observed in all contacts with discrete tonals and relative velocity to the receiver. This thesis demonstrates that the Doppler effect can be exploited to improve the detection process by filtering out contacts that do not …
-
A doppler electrophoresis instrument for macromolecular characterizations
… electrophoresis method involves the use of the Doppler effect to determine a particle’s characteristics. This thesis is concerned with the design and development of an open geometry Doppler electrophoresis instrument for macromolecular characterization in solution where gel characteristics and …
-
Nonlinear Doppler Warp Correction for Acoustic OFDM
… to multipath, frequency selectivity, noise, and Doppler – some of which are more severe. The increased distortion causes many techniques and assumptions made for typical RF communication systems to break down. One of the assumptions that breaks down is that the Doppler effect that the signal …
-
Helicopter blade parameter extraction for purposes of radar target indentification
… on an airborne target cause additional Doppler modulation in the return signal, known as the micro-Doppler effect. Information on the rotating structures can be extracted from this effect. A technique based on time- frequency and tomographic analysis is introduced in this research to …
-
Determination of the Parameter Limits for Artificial Non-random Microwave Signal Detection
<p>The Doppler shift of small bandwidth (several Hertz) microwave signals makes identification of spectral features difficult; the Doppler individual bandwidth shift can be a factor of hundreds or thousands of times greater than the bandwidth. A computer model supplied by the National Aeronautics …
-
Development of a method for calculation of cardiac output using Doppler ultrasound
… of blood pumped by the heart in one minute. The Doppler effect can be used to measure cardiac output by measuring the peak frequency, which is directly proportional to the velocity of blood flowing in the aorta, associated with the Doppler shift signal when an ultrasound beam is incident on the …
-
Doppler channel emulation of high-bandwidth signals
… framework, a module capable of applying Doppler shifting to the input signal was created and tested using DVB-S2 satellite modems. Testing not only verified the functionality of the emulator but also showed that DVB-S2 modems are unequipped to handle the continuous spectral frequency …
-
Sistemas de transmissão multiportadora aplicados em um canal acústico submarino na presença de efeito doppler
… in a multipath channel and in the presence of Doppler effect. The use of OFDM technique allows high transmission rate, increasing the amount of information allocated in each transmitted block. On the other hand, the SCFDMA technique, besides allowing a high transmission rate, has also the …
-
Transport of muonic atoms
… kinematics of an inelastic binary collision. The effect of rotations of the target molecules is treated by defining and computing an effective inelastic energy transfer Q<sub>eff</sub>. The Doppler effect is taken into account by averaging the cross sections over the Maxwellian velocity …
-
Experimental Test of Relativistic Time Dilation by Laser Spectroscopy of Fast Ions
… relativistic time dilation via the transverse Doppler effect. A deviation from the prediction given by Special Relativity would disprove the Relativity Principle and, therefore, single out a physically preferred reference frame. In order to enhance the accuracy of previous experiments in this …
-
Reproducibility and sensitivity of Doppler echocardiographic indices of left ventricular function during exercise
… alternative: the stand-alone continuous wave Doppler echocardiograph. The purposes cf this study were twofold: 1) to examine the repeatability of three Doppler measured indices of LVF during repeated exercise trials, and 2) to determine if induced changes in myocardial contractility would be …
-
An investigation of Turbo Codes over Mobile Wireless Channels
… are made, with reference to short frames. The effects of increasing memory size of component codes, frame sizes, utilising puncturing and errors in channel estimation are investigated over AWGN and Rayleigh fading channels. The decoder systems are compared for complexity as well as for equal …
-
Advances in passive acoustic detection, localization, and tracking applied to unmanned underwater vehicles
… Because the signal is also high-frequency, the Doppler effect on motor noise is observable and I demonstrate that range rate can be measured. Furthermore, measuring motor noise was a superior method to the “detection of envelope modulation on noise” algorithm for estimating the propeller …
-
Advances in Passive Acoustic Detection, Localization, and Tracking Applied to Unmanned Underwater Vehicles
… Because the signal is also high-frequency, the Doppler effect on motor noise is observable and I demonstrate that range rate can be measured. Furthermore, measuring motor noise was a superior method to the “detection of envelope modulation on noise” algorithm for estimating the propeller …
-
A Cavity-stabilized diode laser for dipole trapping of ytterbium
… due to varying intensity in the trap. Since the Doppler effect, recoil broadening and the AC Stark shift are the main sources of inhomogeneous broadening, this trapping scheme is expected to suppress inhomogeneous broadening to a level of 1 Hz.
-
A Comprehensive Hamiltonian Atmospheric Sound Propagation Model for Prediction of Wind Turbine Noise
… due to spatial speed of sound gradients, a full Doppler Effect formulation resulting from wind velocities in any arbitrary direction, proper acoustic energy dissipation during propagation, and ground reflection. The HRT method averts many of the setbacks presented by other common numerical …
-
A lattice boltzmann/s n framework for coupled heat transfer and neutron transport problems
… section is proportional to temperature to mimic Doppler effect. For the one-way coupled, fixed source problems with non-multiplying medium (fission cross section is zero) with the first type of temperature feedback, the magnitude of the minimum temperature-dependent absorption cross section (at …
-
Full 3D Blood Velocity Mapping and Flow Quantification from Doppler Echocardiographic Images
… and flow within the heart using 3D colour Doppler images. The<br/>principal goal of both methods was to overcome the main limitation of Doppler<br/>systems which is that the Doppler effect only measures one component of the velocity<br/>(parallel to the beam direction). For that reason, …
Page 1 of 2