Velocity Estimation

Synthetic aperture radar (SAR) is an invaluable tool for detection of ground moving targets when combined with processing techniques of ground moving target indication (GMTI). This work investigates a simulation methodology for studying impact of sitespecific ground clutter on SAR-GMTI performance. A terrain model is proposed and is based on digital terrain elevation data (DTED) and national land-use land-cover data (NLCD) as provided by the US Geological Survey. The proposed physical optics simulation method capitalizes on high-fidelity digital target models in combination with the proposed terrain model. SAR phase history is generated for a moving commercial target in situ of site specific clutter. The normalized radar cross-section (NRCS) clutter is modeled according to empirical random processes. As SAR imagery and GMTI detection performance depend on clutter, the well-known displaced phase center antenna (DPCA) algorithm is applied to test the performance of the SAR-GMTI algorithm. A Sobel gradient edge-detection technique is used to discern target energy from ground clutter in the SAR image as a means to estimate signal-to-noise-plusinterference ratio (SINR). The proposed model is shown to be suitable for studying the effects of measured clutter on SAR-GMTI performance.

Adaptive spectral estimation techniques are known to provide good spectral resolution and contrast even when the observation window(OW) is very short. In this paper two adaptive techniques are tested and compared to the averaged periodogram (Welch) for blood velocity estimation. The Blood Power spectral Capon (BPC) method is based on a standard minimum variance technique adapted to account for both averaging over slowtime and depth. The Blood Amplitude and Phase Estimation technique (BAPES) is based on finding a set of matched filters (one for each velocity component of interest) and filtering the blood process over slow-time and averaging over depth to find the power spectral density estimate. In this paper, the two adaptive methods are explained, and performance is assessed in controlled steady flow experiments and in-vivo measurements. The three methods were tested on a circulating flow rig with a blood mimicking fluid flowing in the tube. The scanning section is submerged in water to allow ultrasound data acquisition. Data was recorded using a BK8804 linear array transducer and the RASMUS ultrasound scanner. The controlled experiments showed that the OW could be significantly reduced when applying the adaptive methods without compromising spectral resolution or contrast. The in-vivo data was acquired using a BK8812 transducer. OWs of 128, 64, 32 and 16 slow-time samples were tested. Spectrograms with duration of 2 seconds were generated. Welch's method required 128 samples to give a reasonable spectrogram, whereas the BPC only required 32 samples before the SNR became a limiting factor. The BAPES managed to display the spectrogram with sufficient quality at 16 slow-time samples.

In this paper, a case study of in-vivo blood vector velocity images of the carotid artery are presented. The transverse oscillation (TO) method for blood vector velocity estimation has been used to estimate the vector velocities. The carotid arteries of three healthy volunteers are scanned in-vivo at three different positions by experienced sonographers. The scanning regions are: 1) the common carotid artery at 88°beam to flow angle, 2) the common carotid artery and the jugular vein at ϳ 90°beam to flow angle and 3) the bifurcation of the carotid artery. The resulting velocity estimates are displayed as vector velocity images, where the velocity vector is superimposed on a B-mode image showing the tissue structures. The volume flow is found for case 1) and when compared with MRI from the literature, a bias of approximately ϳ 20% is found. The maximum flow velocity within the carotid artery is found to be 0.8 m/s, which is normal for a healthy person. In case 3), the estimated vector velocities are compared with numerical simulations. Qualitatively similar flow pattern can be seen in both simulations and in the vector velocity images. Furthermore, a vortex is identified in the carotid sinus at the deceleration phase after the peak systole. This vortex is seen in all of the three acquired cardiac cycles.

We present a new geodetic velocity solution for Italy and the surrounding areas, obtained from an analysis of continuous and survey-mode Global Positioning System observations collected between 1991 and 2002. We have combined local, regional and global networks into a common reference frame velocity solution, providing a new detailed picture of the regional-scale deformation field in the central Mediterranean. Our velocity estimates are computed with respect to a new stable Eurasian reference frame, constraining the kinematics of the greater African-Eurasian plate boundary system in the study area. We provide strain-rate values for the main seismotectonic districts, which are in good agreement with the seismic deformation inferred from earthquake focal mechanisms. The southern Tyrrhenian area, Calabria, the Apennines, the southeastern Alps, the southern Dinarides and the Albanides display deformation rates at the order of 20-30 nanostrain yr -1 . The Corsica-Sardinia block moves according to Eurasian Plate motions, and there is no indication that the opening of the Tyrrhenian is still active. The Pelagian and Sicilian domains are separated by a northwest-southeast discontinuity, the Sicily Channel rifted area, and marginally significant relative motion between the Pelagian Plateau and the African Plate is also observed. The southern Tyrrhenian is affected by north-south compression and accommodates up to 50 per cent of the Africa-Eurasia relative plate motion, whereas the Calabrian Arc exhibits ∼2 mm yr -1 northwest-southeast extension. The observed deformation pattern suggests the presence of a major approximately north-south tectonic discontinuity separating the Sicilian and Calabrian domains. An extensional boundary observed along peninsular Italy coincides with the distribution of seismogenic faults along the axis of the Apennines. This boundary separates a Tyrrhenian and an Adriatic domain with diverging velocities, orientated north-NNW-ward and northeastward, respectively. The Apennines are extending perpendicularly to the chain axis at rates of less than 3 mm yr -1 , and only in the outer northern Apennines indications of active shortening are observed. Insignificant deformation is observed in the western Po Plain and the western Alps, while the central and eastern Alps display north-south shortening. The eastern Adriatic domain is shortening perpendicular to the Dinaric front with strain rates increasing from north to south. The locus of collision between the Aegean/Balkan system and the Adriatic and Ionian domains is marked by the Kephalonia fault system, which accommodates up to 20±1 mm yr -1 of right-lateral motion. The deformation pattern observed in the peri-Adriatic domain is well described by a counter-clockwise rotation of the Adriatic microplate around a pole located in the western Alps.

In this paper, we introduce and evaluate a novel sonoelastographic technique for imaging shear velocity distributions from propagating shear wave interference patterns (termed crawling waves). A mathematical relationship between local crawling wave spatial phase derivates and shear velocity is presented with phase derivatives estimated using an autocorrelation-based technique. Results from homogeneous phantoms illustrate the ability of sonoelastographic shear velocity imaging to accurately quantify the true shear velocity distribution as verified using time-of-flight measurements. Results from a heterogeneous phantom reveal the ability of sonoelastographic shear velocity imaging to distinguish a stiff circular inclusion with shear velocity contrast comparable to that measured using mechanical testing techniques. High contrast visualization of focal carcinomas in an in-vitro prostrate specimen demonstrates the feasibility of this novel sonoelastographic imaging technique in tissue.

Velocity estimation technique using seismic data is often based on time/distance equations which are independent of direction, and even though we now know that many rocks are quite anisotropic, useful results have been obtained over the years from these isotropic estimates. Nevertheless, if velocities are significantly direction‐dependent, then the isotropic assumption may lead to serious structural interpretation errors. Additionally, information on angle‐dependence may lead to a better understanding of the lithology of the rocks under measurement. VSP and cross‐well data may each lack the necessary aperture to estimate more than two velocity parameters for each wave type, and if the data straddle a symmetry axis, then these may be usefully chosen to be the direct velocities (from time‐and‐distance measurements along the axis) and NMO velocities (from differential time‐offset measurements). These sets of two parameters define ellipses, and provide intermediate models for the variat...

As a mobile robot navigates through an indoor environment, the condition of the floor is of low (or no) relevance to its decisions. In an outdoor environment, however, terrain characteristics play a major role on the robot's motion. Without an adequate assessment of terrain conditions and irregularities, the robot will be prone to major failures, since the environment conditions may greatly vary. As such, it may assume any orientation about the three axes of its reference frame, which leads to a full six degrees of freedom configuration. The added three degrees of freedom have a major bearing on position and velocity estimation due to higher time complexity of classical techniques such as Kalman filters and particle filters. This article presents an algorithm for localization of mobile robots based on the complementary filtering technique to estimate the localization and orientation, through the fusion of data from IMU, GPS and compass. The main advantages are the low complexity of implementation and the high quality of the results for the case of navigation in outdoor environments (uneven terrain). The results obtained through this system are compared positively with those obtained using more complex and time consuming classic techniques.

Regularization is the process of extracting an image from pre-existed image. The aim is to improve the regularization of image by a sparsity of corner points this approach is proposed to reduce the de-blurring problem and the artifacts in the iterative image restoration. This paper implements a robust regularization for iterative image reconstruction by using concept of Analysis-based regularization. An optimization algorithm is developed for the corresponding optimization problem. In the concept of Analysis-based regularization can achieve the better form to recovery for small objects when compared with quadratic regularization and also it gives clear image than the conventional pixel-based regularization. In this the image de-noising and de-blurring experiments explained with high performance of regularization especially in aspects of restoring edge regions and also many image related problems. These type of image regularizations are detected based on an edge detector and a corner...

The objective of this study is to estimate the S-wave velocity structure of the Taichung basin in a near-fault region, which is needed for strong-motion evaluation for the 1999 Chi-Chi earthquake. We have conducted array measurements of microtremors with a total of 12 arrays at four sites and single-station measurements of microtremors at 48 sites in and around the Taichung basin. Based on the Rayleighwave inversion technique using phase velocities estimated from array records of microtremors, we find that a thick layer (the thickness of about 1000 to 1400 m) with an S-wave velocity of V S 1100 m/sec exists in the east-central part of the Taichung basin. We estimate the thicknesses of sedimentary layers above the pre-Tertiary bedrock at 48 sites to fit calculated peak and trough frequencies of horizontal-to-vertical spectral ratios of Rayleigh waves to observed peak and trough frequencies, assuming the same S-wave velocities estimated using array records. The pre-Tertiary bedrock depth was estimated to be about 5 to 6 km in this region. The estimated thickness of the layer with V S ‫ס‬ 1100 m/sec is largest in the east-central part of the basin and rapidly decreases to less than 400 m in the northeastern and western parts inside the basin. The estimated S-wave velocity structures reasonably explain arrival time of initial P and S waves of aftershock records observed by .

This paper introduces a method for representing, communicating and fusing distributed, noisy and uncertain observations of objects by multiple robots. The approach relies on re-parameterization of two-dimensional Gaussian distri- butions that are used to represent the positions of all players and the ball. The approach enables two or more observers to achieve greater eective sensor coverage of the environment and improved accuracy in object position estimation. We demonstrate empirically that, using this approach, more observers achieve more accurate object position estimates. Two dierent procedures for merging Gaussian distributions were implemented and tested in the RoboCup Soccer Server, a simulated environment for robotic soccer. We also present the first results obtained with middle-size league robots.

Arabian Gulf is connected to Indian Ocean and located in the south-west of the Zagros Trust Belt. To investigate sea level variations within the west of Arabian Gulf, monthly means of sea level at 13 tide gauges along the coast of Saudi Arabia and Bahrain, available in the database of the Permanent Service for Mean Sea Level (PSMSL), are studied. We analyzed individually the monthly means at each station, and estimated secular sea level rate by a robust linear trend fitting. We computed the average relative sea level rise rate of 1.96 ± 0.21 mm/yr within the west of Arabian Gulf based on 4 stations spanning longer than 19 years. Vertical land motions are included into the relative sea level measurements at the tide gauges. Therefore sea level rates at the stations are corrected for vertical land motions using the ICE-5G v1.2 VM4 Glacial Isostatic Adjustment (GIA) model then we found the average sea level rise rate of 2.27 mm/yr. Bahrain International GPS Service (IGS) GPS station, which is close to the Mina Sulman tide gauge station in Bahrain, is the only continuous GPS station accessible in the region. The weekly GPS time series of vertical component at Bahrain IGS-GPS station referring to the ITRF97 from 1999.2 to 2008.6 are downloaded from ∼tah/. We fitted a linear trend with an annual signal and one break to the GPS vertical time series and found a vertical land motion rate of 0.48 ± 0.11 mm/yr. Assuming the vertical rate at Bahrain IGS-GPS station represents the vertical rate at each of the other tide gauge stations studied here in the region, we computed average sea level rise rate of 2.44 ± 0.

Arabian Gulf is connected to Indian Ocean and located in the south-west of the Zagros Trust Belt. To investigate sea level variations within the west of Arabian Gulf, monthly means of sea level at 13 tide gauges along the coast of Saudi Arabia and Bahrain, available in the database of the Permanent Service for Mean Sea Level (PSMSL), are studied. We analyzed individually the monthly means at each station, and estimated secular sea level rate by a robust linear trend fitting. We computed the average relative sea level rise rate of 1.96 ± 0.21 mm/yr within the west of Arabian Gulf based on 4 stations spanning longer than 19 years. Vertical land motions are included into the relative sea level measurements at the tide gauges. Therefore sea level rates at the stations are corrected for vertical land motions using the ICE-5G v1.2 VM4 Glacial Isostatic Adjustment (GIA) model then we found the average sea level rise rate of 2.27 mm/yr. Bahrain International GPS Service (IGS) GPS station, w...

Lithium niobate (LiNbO 3) films have been grown at 490 C on diamond-coated silicon substrates by radio-frequency magnetron sputtering. A multi-step process was developed to produce thick layers on diamond with a good structure and a smooth morphology. To assess the structural quality of our films, we performed X-ray diffraction, transmission electron microscopy and atomic force microscopy of the films. The structure is conserved whatever the film thickness. A delay line structure of wavelength of 28 mm was realized and transducers were deposited on top of LiNbO 3. The objective was to verify the high velocity in such a multi-layered structure. The first results indicated a SAW velocity estimated of 8200 m/s and a coupling factor was k 2 around 1%. The film growth, the technology and the electrical measurements are described in this paper.

This document describes efforts to best characterize seismogenic deformation in and near California. The rate of hazardous earthquakes in California is expected to be proportional to deformation rates; in particular, the rates at which faults slip. Fault slip rates are determined from offsets of geologic and geomorphic features of measured age and by modeling geodetically determined surface displacement rates. Extensive use of geodesy in the form of Global Positioning System (GPS) observations is a new feature brought into the Working Group on California Earthquake Probabilities (WGCEP) forecasts for the Uniform California Earthquake Rupture Forecast, version 3 (UCERF3) model. Geodetic measurements are potentially more spatially comprehensive than geologic offset observations, which can be clustered. Applying either type of data is subject to considerable uncertainty. Geologic observations have dating and other measurement errors, and they often must be extrapolated long distances o...

The virtual source method (VSM) is a useful tool for imaging below complex overburden and monitoring in the presence of time-varying overburden. This concept, when extended to crosswell geometry produces data comparable to real crosswell data. Using a field data example we demonstrate that virtual crosswell data is kinematically comparable to real crosswell data, but the virtual crosswell method possesses flexibilities, which are difficult to achieve in a real crosswell survey. Some of these flexibilities include the ability of the virtual source to radiate either horizontally or vertically and the possibility for the virtual source to radiate only P-or only S-waves. It is also possible to create virtual crosswell data that contain only the direct arrivals or only the reflections. These features of the virtual crosswell method should make it useful for crosswell tomography, imaging and reservoir monitoring for moderate interwell distances.

His research interests include the fields of digital and wireless communication, location, and navigation. Nadezda Sokolova is a M.Sc. student in the PLAN group of the University of Calgary, Canada. She also holds a B.Sc. and M.Sc. in Space and Aeronautical Engineering from Narvik University, Norway. Her research interests are in the field of indoor positioning and precise velocity determination using GPS and GPS/INS integration. Professor Gérard Lachapelle holds a CRC/iCORE Chair in Wireless Location in the Department of Geomatics Engineering, the University of Calgary, where he has been a professor since 1988. He heads the Position, Location And Navigation Group and supervises over 25 research engineers and graduate students. He has been involved in a multitude of Global Navigation Satellite Systems (GNSS) R&D projects since 1980, ranging from RTK positioning to indoor location and GNSS signal processing enhancements. He has received numerous awards for his accomplishments.

The U.S. Navy hydrophone arrays (SOSUS) record seismoacoustic events in a range of frequencies which includes earthquake and explosive sources as well as those relevant to submarine detection, for which they were designed. In the Norwegian Sea we compare detection of seismoacoustic events on SOSUS with seismic detection by the arrays on land in Norway. We also study seismic activity along the spreading centers between Iceland and Svalbard in an attempt to discern any difference in levels of seismicity associated with different sections of the ridge system. Currently, we have assigned archive channels to focus on activity along the Mohns ridge. During March 1995 we recorded many T-phases whose sources have been located along the Mohns ridge using beam steering. Analysis of beamformed data for this continuous one-month period revealed several dozen acoustic events emanating from the southern Mohns ridge and about one third that number from the northern Mohns ridge. Part of this difference is probably due to the choice of beams for the archived data, which emphasizes the southern Mohns ridge, but some of the difference likely reflects the current level of magmatic/tectonic activity. About 10% of the recorded T-phases for this period are preceded by an arrival with greater low frequency content, most likely the P-phase. Approximately two dozen acoustic events were recorded by all channels during the March 95 period suggesting a more distant or larger source, possibly a regional or even teleseismic earthquake. Two of these events correspond to regional events listed in the Center for Monitoring Research (CMR) bulletin, both for which P-and T-phases are observed. The hydroacoustic data have been archived since February 1995 so it is too early to determine systematic patterns in seismic activity or to compile reliable statistics on the relative detection thresholds of the SOSUS system vs the land arrays that can monitor the Norwegian Sea. This work, along with quantitative characterization of the acoustic signals as a function of source parameters, will be the focus of our upcoming investigative year.

The energy loss of Li, C and O ions in polypropylene absorber foils has been measured using 15 UD Pelletron Accelerator facility at Inter University Accelerator Centre (IUAC), New Delhi, India. The actual experiment has been performed in low flux chamber attached to the General Purpose Scattering Chamber (GPSC). These experimental energy loss values have been compared with the computed values based on various empirical/semi-empirical formulations. Some interesting trends have been observed.

The high resolution obtained through the use of VLBI gives an unique opportunity to directly observe the interaction of an expanding radio supernova with its surrounding medium. We present here results from our VLBI observations of the young supernovae SN 1979C, SN 1986J, and SN 2001gd. 13 13 MAPT, AA, and ER thank the organizers for funding to attend the conference.

Environmental monitoring by means of Remote Sensing methodologies is one of the most interesting and important application field of image processing techniques. In this field, a very important role is played by Synthetic Aperture Radar (SAR) images, that posses an high spatial resolution and that can be produced in all weather conditions. This paper presents a complete digital signal processing chain for the automatic detection of ships in SAR images and for the computation of an estimate of ship velocities. A particular attention has been devoted to two problems: the prefiltering problem which aims to reduce the speckle noise in the image, and the robustness problem that is related to the optimization of the true-target detectionhejection capability. The whole chain has been first simulated and tested on a sequential machine, namely a MicroVAX 11, and then it has been ported on a parallel architecture based on a hypercube of IMS T800 transputers.

We are investigating the use of ultrasound in Haptic applications. Initially a brief background of ultrasonic transducers and its characteristics were presented. Then a theoretical research was documented to understand the concepts that govern haptics. This section also discusses the algorithm adopted by various researches to implement haptics in the professional world. Then investigations were made to understand the behavior of ultrasonic transducers and conduct software simulations to obtain various results. At first simulations were conducted on Field II software. This simulations involved the creation of elements in transducers, transducer's spatial impulse responses, transducer's impulse response in time and frequency domain, effect of adding apodization to the transducers, pulse echo response of the transducers, beam profile variation along the focal length of the transducers. Then a Matlab based GUI was used to study the relationship between number of elements in transducers, the frequency of the input signal and duty cycle variation of the input wave. A concept of phase shift, which explains the time delay generation was also coded in Matlab.

Ultrasound systems are widely used to visualize in real-time internal structures and blood flow velocity distributions. The latter are estimated from the received ultrasound radio frequency (RF) signals using a mean frequency estimator, capable of estimating the temporal and spatial mean frequency within a given depth and time window (estimation window). Since ultrasound RF-signals are composed of three major signal components (reflections, scattering and noise) it is necessary to suppress the power of the reflections or reverberations (stationary echo removal) to estimate the temporal mean frequency of the signal component induced by scattering originating from red blood cells. However, the stationary echo removal filter in front of the mean frequency estimator will restrict the temporal mean frequency estimation range because the power of the signal component induced by the slowly moving blood is suppressed as well. This article describes a stationary echo removal filter, acting in the RF-domain and adaptive to the temporal mean frequency of the signal component induced by stationary or slowly moving reflections and reverberations. Furthermore, a comparison in performance of this adaptive stationary echo removal filter and several static stationary echo removal filters is presented. For direct comparison of these filter algorithms as far as the effect on the temporal mean frequency estimation range is concerned, the same signal conditions in combination with the same RF-domain mean frequency estimator were used in this comparison. It could be demonstrated that the adaptive echo removal filter, in combination witb the RF-domain mean frequency estimator used, exhibits the best performance.

A new procedure is proposed for estimating river discharge hydrographs during flood events, using only water level data measured at a gauged site, as well as 1-D shallow water modelling and sporadic maximum surface flow velocity measurements. During flood, the piezometric level is surmised constant in the vertical plane of the river section,

Coastal communities in the western United States face risks of inundation by distant tsunamis that propagate across the Pacific Ocean as well as local tsunamis produced by great (M w [ 8) earthquakes on the Cascadia subduction zone. In 1964, the M w 9.2 Alaska earthquake launched a Pacific-wide tsunami that flooded Cannon Beach, a small community (population 1640) in northwestern Oregon, causing over $230,000 in damages. However, since the giant 2004 Indian Ocean tsunami, the 2010 Chile tsunami and the recent 2011 Tohoku-Oki tsunami, renewed concern over potential impacts of a Cascadia tsunami on the western US has motivated closer examination of the local hazard. This study applies a simple sediment transport model to reconstruct the flow speed of the most recent Cascadia tsunami that flooded the region in 1700 using the thickness and grain size of sand layers deposited by the waves. Sedimentary properties of sand from the 1700 tsunami deposit provide model inputs. The sediment transport model calculates tsunami flow speed from the shear velocity required to suspend the quantity and grain size distribution of the observed sand layers. The model assumes a steady, spatially uniform tsunami flow and that sand settles out of suspension forming a deposit when the flow velocity decreases to zero. Using flow depths constrained by numerical tsunami simulations for Cannon Beach, the sediment transport model calculated flow speeds of 6.5-7.6 m/s for sites within 0.6 km of the beach Electronic supplementary material The online version of this article (

In this work, a new GPS carrier phase-based velocity and acceleration determination method is presented that extends the effective range of previous techniques. The method is named 'EVA', and may find applications in fields such as airborne gravimetry when rough terrain or water bodies make difficult or impractical to set up nearby GPS reference receivers. The EVA method is similar to methods such as Kennedy (Precise acceleration determination from carrier phase measurements. In: Proceedings of the 15th international technical meeting of the satellite division of the Institute of Navigation. ION GPS 2002, Portland pp 962-972, 2002b) since it uses L1 carrier phase observables for velocity and acceleration determination. However, it introduces a wide network of stations and it is independent of precise clock information because it estimates satellite clock drifts and drift rates 'on-the-fly', requiring only orbit data of sufficient quality. Moreover, with EVA the solution rate is only limited by data rate, and not by the available precise satellite clocks data rate. The results obtained are more robust for long baselines than the results obtained with the reference Kennedy method. An advantage of being independent of precise clock information is that, beside IGS Final products, also the Rapid, Ultra-Rapid (observed) and Ultra-Rapid (predicted) products may be used. Moreover, the EVA technique may also use the undifferenced ionosphere-free carrier phase combination (LC), overcoming baseline limitations in cases where ionosphere gradients may be an issue and very low biases are required. During the development of this work, some problems were found in the velocity estimation process of the Kennedy method. The sources of the

A new procedure is proposed for estimating river discharge hydrographs during flood events, using only water level data measured at a gauged site, as well as 1-D shallow water modelling and sporadic maximum surface flow velocity measurements. During flood, the piezometric level is surmised constant in the vertical plane of the river section,

The Gulf of Aqaba is one of the most active places around Egypt, with several earthquake sequences having occurred there through ancient and modern times. In the last century, four earthquake sequences took place in the gulf (1983, 1990, 1993, and 1995). Recently, on 27 June 2015, a sequence of 96 earthquakes with local magnitudes ranging from 0.7 to 5.2 was recorded by the Egyptian National Seismological Network (ENSN). On 16 May 2016, another earthquake sequence started and continued for several consecutive days, with 95 events with local magnitudes ranging from 1.6 to 5.5 being centered south of the 27 June 2015 sequence. In this paper, we analyse the complete waveform and polarity data set of both earthquake sequences to determine their focal mechanisms and to update our knowledge of the stress field in the Gulf of Aqaba. Through the results obtained, we conclude that, the Gulf of Aqaba is affected by a primary structure of a left-lateral strike-slip fault with a minor normal component in most segments. Our study also infers the presence of a secondary structure, which is indicated to be a right-lateral strike-slip with a minor reverse component.

This work contains no material which has been accepted for the award of any other degree or diploma in any university or other tertiary institution and, to the best of my knowledge and belief, contains no material previously published or written by another person, except where due reference has been made in the text. I give consent to this copy of my thesis, when deposited in the University Library, being available for loan and photocopying.

Systematic full-scale but small avalanche experiments have been started since 2016 in Niseko, a ski resort in Hokkaido, Japan. Although the vertical drop in the test sites are 100 to 200 m, they have advantages that we are able to access relatively easy and can expect both dry avalanches in February and wet ones in March. On top of that, it has a potential that we can look at the phenomena closer and investigate the detailed structures and mechanism of avalanches. Although the artificial releases and measurements were not always successful so far, data for three wet snow avalanches were obtained and they revealed that the combination of different data is effective measures to characterize their structures.

This paper reports the development of microelectromechanical metrology tools to characterize liquid and gaseous jets generated from microfabricated nozzles with diameters ranging from 1 to 12 m. Microcantilever sensors with either piezoresistive elements or integrated heating elements have been fabricated and applied to measure thrusts, velocities, and heat transfer characteristics of micro/nanojets. Piezoresistive cantilever measurements showed that liquid butane microjets from a 6 m diameter nozzle achieved velocities 40-60 m/s for driving pressures 0.6-1.4 MPa. Jet velocities estimated from cantilever measurements agreed well with shadowgraphy results within 12.5% without any correction factor. A microcantilever with integrated heating elements measured cooling capacities of liquid butane microjets on the order of 10 −5 W/K.

For the passive estimation of directions of arrivals (DOAs) of transmitting sources from an antenna array, high resolution estimators can be achieved from maximum likelihood or signal subspace based concepts, provided that certain model assumptions are satisfied. For the signal subspace class of methods, the sources are nearly always regarded as being stationary during the observation interval of the array data. If this is the case, and if all the other model assumptions are valid, then the DOA can be estimated to arbitrary accuracy in the presence of noise by observing the data over a sufficiently long time interval. When sources are in fact moving relative to the receiving array, errors are induced in signal subspace methods. These depend on the extent of the source motion. Hence there is a trade-off between decreasing noise errors and increasing motion errors as the observation time is increased, and some optimum observation period exists. In some cases, however, even the performance at the optimum observation interval may be unsatisfactory, and alternative approaches are desirable. Signal subspace concepts break down when sources are moving, and maximum likelihood methods for moving sources are computationally expensive. To overcome these problems three novel algorithms have been developed for the joint estimation of source position and velocity from a batch of array data for sources moving with constant angular velocity. These allow increased accuracy in the source position determination, and provide unbiased velocity estimates. The performance of the estimators is compared to the Cramer-Rao lower bound.

Environmental monitoring by means of Remote Sensing methodologies is one of the most interesting and important application field of image processing techniques. In this field, a very important role is played by Synthetic Aperture Radar (SAR) images, that posses an high spatial resolution and that can be produced in all weather conditions. This paper presents a complete digital signal processing chain for the automatic detection of ships in SAR images and for the computation of an estimate of ship velocities. A particular attention has been devoted to two problems: the prefiltering problem which aims to reduce the speckle noise in the image, and the robustness problem that is related to the optimization of the true-target detectionhejection capability. The whole chain has been first simulated and tested on a sequential machine, namely a MicroVAX 11, and then it has been ported on a parallel architecture based on a hypercube of IMS T800 transputers.

Continuing research has concentrated on the elimination of the problem of sensitivity to parameter variation of induction motor drive. This paper presents a simple method for simultaneous estimation of rotor speed and stator resistance in sensorless indirect vector controlled induction motor drive. This method is based on luenberger observer and the stability of this observer is proved by the lyapunov’s theorem, by using measured and estimated stator currents and estimated rotor flux. Finally the feasibility of the schem is verified by simulation. However, at low speed of rotation we get successful resistance identification.

This paper presents a simple and easy to implement sensor data fusion algorithm, using a Kalman filter (KF) in a loosely coupled scheme, for estimation of the velocity and position of an object evolving in a three dimensional space. A global positioning system (GPS) provides the position measurement while the velocity measurement is taken from the optical flow sensor, finally, the inertial navigation system (INS) gives the acceleration, which is considered as the input of the system. Real time experimental results are shown to validate the proposed algorithm.

We address the problem of position estimation for a rigid body using an inertial measurement unit (IMU) and a set of spatially distributed magnetometers. We take advantage of the magnetic field disturbances usually observed indoors. This is particularly relevant when GPS is unavailable (e.g. during military operations in urban areas). We illustrate our technique with several experimental results obtained with a Kalman filter. We also present our testing bench which consists of low cost sensors (IMU and magnetometers).

Velocity estimation is generally under-determined. To obtain a pleasing result we impose some type of regularization criteria such as preconditioning(Harlan, 1996), limiting inversion solutions to large singular values (Rowbotham and Pratt, 1997), or characterizing the model through a small number of spline coefficients (Ji, 1997). These methods all create velocity models that can correctly model the recorded travel times, but are often geologically unrealistic. To create more geologically feasible velocity models and to speed up convergence, Michelena and Harris (1991) suggested using varying sized grid cells. Unfortunately, such a parameterization is prone to error when the wrong size blocks are chosen (Delprat-Jannaud and Lailly, 1992). Other authors have suggested locally clustering grid cells (Carrion, 1991) or characterizing the velocity model as a series of layers (Kosloff et al., 1996). These methods are also susceptible to errors when the wrong parameterization is chosen. An attractive alternative approach is to add an additional model regularization term to the objective function (van Trier, 1990). In theory, this regularization term should be the inverse model covariance matrix (Tarantola, 1987) obtained from some a priori information sources.

The motion detection problem occurs frequently in many applications connected with computer vision. Researchers have studied motion detection based on naturally occurring biological circuits for over a century. In this paper, we propose and analyze a motion detection circuit which is based on nerve membrane conduction. It consists of two unidirectional neural networks connected in an opposing fashion. Volterra input-output (I-O) models are then derived for the network so that velocity estimation can be cast as a parameter estimation problem. The technique is demonstrated through simulation.

Most iris based biometric systems require a lot of cooperation from the users so that iris images of acceptable quality may be acquired. Features from these may then be used for recognition purposes. Relatively fewer works in literature address the question of less cooperative iris acquisition systems in order to reduce constraints on users. In this paper, we describe our ongoing work in designing and developing such a system. It is capable of capturing images of the iris up to distances of 8 meters with a resolution of 200 pixels across the diameter. If the resolution requirement is decreased to 150 pixels, then the same system may be used to capture images from up to 12 meters. We have incorporated velocity estimation and focus tracking modules so that images may be acquired from subjects on the move as well. We describe the various components that make up the system, including the lenses used, the imaging sensor, our auto-focus function and velocity estimation module. All the hardware components are Commercial Off The Shelf (COTS) with little or no modifications. We also present preliminary iris acquisition results using our system for both stationary and mobile subjects.

Most iris based biometric systems require a lot of cooperation from the users so that iris images of acceptable quality may be acquired. Features from these may then be used for recognition purposes. Relatively fewer works in literature address the question of less cooperative iris acquisition systems in order to reduce constraints on users. In this paper, we describe our ongoing work in designing and developing such a system. It is capable of capturing images of the iris up to distances of 8 meters with a resolution of 200 pixels across the diameter. If the resolution requirement is decreased to 150 pixels, then the same system may be used to capture images from up to 12 meters. We have incorporated velocity estimation and focus tracking modules so that images may be acquired from subjects on the move as well. We describe the various components that make up the system, including the lenses used, the imaging sensor, our auto-focus function and velocity estimation module. All the hardware components are Commercial Off The Shelf (COTS) with little or no modifications. We also present preliminary iris acquisition results using our system for both stationary and mobile subjects.

105 synthetic time series replicating GNSS 3D position series are analyzed independently by nine different groups within the RENAG consortium in order to characterize the variability in estimations of long-term velocities. The main objective is not a detailed study of the parameters and sources controlling velocity variations, but simply to establish first-order conclusions regarding the uncertainties on GNSS velocity estimations as a function of the different analysis methods and software. Because the true velocities are known, our results are presented in terms of velocity biases (i.e. deviations of the estimated velocities relative to the expected values). Statistics on these biases can then be used as indicators of the potential precision of actual GNSS velocities. To first order, the nine methods and software of time series analysis provide horizontal (resp. vertical) velocity estimations at precisions better than 1.0 mm/a (resp. 2.0 mm/a). None of the tested methods or softwar...

Loop detectors are the preeminent vehicle detector for freeway traffic surveillance. Although single loops have been used for decades, debate continues on how to interpret the measurements. Many researchers have sought better estimates of velocity from single loops. The preceding work has emphasized techniques that use many samples of aggregate flow and occupancy to reduce the estimation error. Although rarely noted, these techniques effectively seek to reduce the bias due to long vehicles in measured occupancy. This paper presents a different approach, using a new aggregation methodology to estimate velocity and reduce the impact of long vehicles in the original traffic measurements. In contrast to conventional practice, the new estimate significantly reduces velocity estimation errors when it is not possible to control for a wide range of vehicle lengths.

Loop detectors are the preeminent vehicle detector for freeway traffic surveillance. Although single loops have been used for decades, debate continues on how to interpret the measurements. Many researchers have sought better estimates of velocity from single loops. The preceding work has emphasized techniques that use many samples of aggregate flow and occupancy to reduce the estimation error. Although rarely noted, these techniques effectively seek to reduce the bias due to long vehicles in measured occupancy. This paper presents a different approach, using a new aggregation methodology to estimate velocity and reduce the impact of long vehicles in the original traffic measurements. In contrast to conventional practice, the new estimate significantly reduces velocity estimation errors when it is not possible to control for a wide range of vehicle lengths.

We review the status of current sea-level observing systems with a focus on the coastal zone. Tide gauges are the major source of coastal sea-level observations monitoring most of the world coastlines, although with limited extent in Africa and part of South America. The longest tide gauge records, however, are unevenly distributed and mostly concentrated along the European and North American coasts. Tide gauges measure relative sea level but the monitoring of vertical land motion through highprecision GNSS, despite being essential to disentangle land and ocean contributions in tide gauge records, is only available in a limited number of stations (25% of tide gauges have a GNSS station at less than 10 km). Other data sources are new in-situ observing systems fostered by recent progress in GNSS data processing (e.g. GPS reflectometry, GNSS-towed platforms) and coastal altimetry currently measuring sea level as close as 5 km from the coastline. Understanding observed coastal sea level also requires information on various contributing processes, and we provide an overview of some other relevant observing systems, including those on (offshore and coastal) wind-waves and water density and mass changes.

Estimation of the maximum Doppler spread or, equivalently, the vehicle velocity, is useful in improving handoff algorithms and necessary for the optimal tuning of parameters for systems that adapt to changing channel conditions. We provide a novel velocity estimator based on the spectral moments of the in-phase and the quadrature phase components or the envelope of the received signal. We characterize the joint effects of the Ricean factor, the directivity and the angle of nonisotropic scattering, and the effects of additive white noise on our estimator and other covariance-based velocity estimators analytically. We also prove the mean-square consistency of the covariance-based velocity estimators under some assumptions on the angle of arrival distribution. Simulations illustrate our approach and compare with existing techniques.