3D oceanographic data compression using 3D-ODETLAP

This paper describes a 3D environmental data compression technique for oceanographic datasets. With proper point selection, our method approximates uncompressed marine data using an over-determined system of linear equations based on, but essentially different from, the Laplacian partial differential equation. Then this approximation is refined via an error metric. These two steps work alternatively until a predefined satisfying approximation is found. Using several different datasets and metrics, we demonstrate that our method has an excellent compression ratio. To further evaluate our method, we compare it with 3D-SPIHT. 3D-ODETLAP averages 20% better compression than 3D-SPIHT on our eight test datasets, from World Ocean Atlas 2005. Our method provides up to approximately six times better compression on datasets with relatively small variance. Meanwhile, with the same approximate mean error, we demonstrate a significantly smaller maximum error compared to 3D-SPIHT and provide a feature to keep the maximum error under a user-defined limit

Performance prediction and improvement of a Bistatic Passive coherent location Radar.

Passive Coherent Location (PCL) radar has proved to be feasible in a number of experimental systems, but the lack of comprehensive, published flight trials detracts somewhat from serious consideration of these PCL systems for operational applications, such as Air Traffic Control (ATC). The carrying out of flight trials is, in any case, difficult and very expensive. This dissertation presents a method for accurately predicting the performance of a bistatic passive coherent location radar with the effects of the environment taken into account. The effect of the environement on a propagating electromagnetic wave is obtained from the Advanced Refractive Effects Prediction System (AREPS) model. The resulting performance predictions, in the form of spatial signal-to-noise ratio (SNR), signal-to-interference ratio (SIR) and signal-to-noise-plus-interference ratio (SNIR) maps, provide a powerful planning tool for the application of systems such as ATC. Furthermore, the spatial coverage maps, based on the bistatic radar equation, can be related to a particular probability of detection and false alarm as well as to a required dynamic range of the receiver ADC. Overall, the method provides a visual, as well as a quantitative measure of radar coverage with region-specific atmospheric and terrain effects taken into account. The method proposed in this dissertation offers a marked improvement over traditional performance prediction methods based on the bistatic radar equation within a free space or flat terrain environment. It is understood that the direct path signal of the illuminating transmitter is the cause of some severe limitations within a PCL system. In the interest of suppressing the strong direct signal before the ADC and to complement the development of the prediction method, an antenna pattern was synthesised and applied to an array of folded dipoles in order to place a null in the direction of the strong transmitter. The synthesised antenna pattern and its improvement on the performance of the PCL system was then evaluated using the proposed prediction method presented in this dissertation

Algorithms for the visualization and simulation of mobile ad hoc and cognitive networks

Visualization and simulation are important aspects of most advanced engineering endeavors. They may provide important insights into the functionality and perfor- mance of a system during the design and evaluation stage of the system's development. This thesis presents a number of algorithms and simulation algorithms that may be used for the design and evaluation of two types of engineered systems, mobile ad hoc and cognitive networks. The ¯rst set of algorithms provides signal radiation pattern and digital terrain visualization capabilities to OMAN, a mobile ad hoc network sim- ulator developed at Drexel University. The second set of algorithms provides a more general visualization capability for displaying complex graphs. These algorithms fo- cus on simplifying a complex graph in order to allow a user to explore its underlying basic structure. The thesis closes with a description of a GPU-based implementation of a set of spectrum-sensing algorithms. Spectrum sensing is an important function- ality needed for cognitive networks. The computational speed-ups provided by the GPU implementation o®er the possibility of real-time spectrum-sensing for adaptive, cognitive networks.M.S., Computer Science -- Drexel University, 200

Methods for Aiding Height Determination in Pseudolite-Based Reference Systems Using Batch Least-Squares Estimation

There are many situations in which GPS is either unable to provide the desired level of accuracy or is unavailable. Use of a pseudolite-based reference system for navigation can be a means for positioning during these times. While there are advantages in using a pseudolite-based reference system, there are still implementation issues and deficiencies that must be addressed. In many cases, a pseudolite system with ground-based transmitters has difficulty determining the height of the receiver accurately. This is due to the poor vertical observability inherent in the geometry of the system. A common approach in naval applications for solving the problem of poor vertical observability is to use a height constraint, which is well known when travelling on a surface of water. For a ground-based vehicle, knowledge of the surface topography can be obtained, but it cannot be readily used in the same manner as in marine cases, since the height is often a varying function of position. This research investigates and develops five methods of incorporating the known surface topography in a non-linear batch least squares estimation algorithm using carrier-phase measurements from pseudolites. The floating point carrier-phase ambiguities are estimated in this process. Real and simulated data sets are used to evaluate the performance of the five algorithms. In simulation, all methods performed equally well on a flat surface. When simulating a hill, constraining the solution to lie in a plane tangent to the surface topography appeared to aid the solution with the best knowledge of the terrain. Use of a pseudo-measurement, a commonly used approach, did not provide the best results, and indicates the inadequacy of using this method for pseudolite-based systems. Results using data from a real system on a ground-based vehicle demonstrated sub-decimeter level positioning accuracy in all three dimensions

Flood Mapping And Flood Damage Estimation Using GIS

Flood mapping has been used widely in many countries nowadays as a method to encounter this natural hazard phenomenon. In the past few years, studies about the flood analysis and modeling used to take years. But now, with the facilitation of Geographical Information System (GIS) automated process, the studies are faster and even accurate in modeling the flood inundation area. The used of GIS is essential as a planning tool for floods, educating the populations at risk and managing floods as they actually rise. Features in the GIS itself such as the 3-D Visualization and detailed hydrological characteristic help a lot in defining areas which is vulnerable to flood. Generally, flood mapping can identify the effects of flooding and those effects are represented in hazard and risk mapping. The main advantage of using GIS for flood management is that it not only generates a visualization of flooding but also creates potential to further analyze this product to estimate probable damage due to flood. This paper is to demonstrateth e use of GIS in constructing the flood map at studies area. The map then are derive into Digital Terrain Model (DTM) to make the identification in flood vulnerable areas easier which provide high detailed representation of the topographical variations in the Earth's surface

Effects of the troposphere upon radio communications and implications for weather measurement

The aim of this research is to use observations of Very High Frequency (VHF) radio wave propagation to estimate the refractive index of air over a propagation path and subsequently the pressure, temperature, and water vapour. This can be accomplished by transmitting a known signal from one spatial location to another, and accurately timing the signal. The research develops methods for accomplishing the required measurements by means of a passive bistatic radar setup with a cooperative target. Such an approach overcomes the timing problems that are normally associated with propagation measurements. A network of these measurements can then be assimilated into a numerical weather prediction model, such as that used by the Australia Bureau of Meteorology, to increase weather forecast capability. Importantly, this research develops novel techniques to relate the propagation of radio waves from weather data. These techniques are important in their own right to identify true propagation paths.Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 201

Design of a walking robot

Carnegie Mellon University's Autonomous Planetary Exploration Program (APEX) is currently building the Daedalus robot; a system capable of performing extended autonomous planetary exploration missions. Extended autonomy is an important capability because the continued exploration of the Moon, Mars and other solid bodies within the solar system will probably be carried out by autonomous robotic systems. There are a number of reasons for this - the most important of which are the high cost of placing a man in space, the high risk associated with human exploration and communication delays that make teleoperation infeasible. The Daedalus robot represents an evolutionary approach to robot mechanism design and software system architecture. Daedalus incorporates key features from a number of predecessor systems. Using previously proven technologies, the Apex project endeavors to encompass all of the capabilities necessary for robust planetary exploration. The Ambler, a six-legged walking machine was developed by CMU for demonstration of technologies required for planetary exploration. In its five years of life, the Ambler project brought major breakthroughs in various areas of robotic technology. Significant progress was made in: mechanism and control, by introducing a novel gait pattern (circulating gait) and use of orthogonal legs; perception, by developing sophisticated algorithms for map building; and planning, by developing and implementing the Task Control Architecture to coordinate tasks and control complex system functions. The APEX project is the successor of the Ambler project

Flood Mapping And Flood Damage Estimation Using GIS

Flood mapping has been used widely in many countries nowadays as a method to encounter this natural hazard phenomenon. In the past few years, studies about the flood analysis and modeling used to take years. But now, with the facilitation of Geographical Information System (GIS) automated process, the studies are faster and even accurate in modeling the flood inundation area. The used of GIS is essential as a planning tool for floods, educating the populations at risk and managing floods as they actually rise. Features in the GIS itself such as the 3-D Visualization and detailed hydrological characteristic help a lot in defining areas which is vulnerable to flood. Generally, flood mapping can identify the effects of flooding and those effects are represented in hazard and risk mapping. The main advantage of using GIS for flood management is that it not only generates a visualization of flooding but also creates potential to further analyze this product to estimate probable damage due to flood. This paper is to demonstrateth e use of GIS in constructing the flood map at studies area. The map then are derive into Digital Terrain Model (DTM) to make the identification in flood vulnerable areas easier which provide high detailed representation of the topographical variations in the Earth's surface

Proceedings of the Augmented VIsual Display (AVID) Research Workshop

The papers, abstracts, and presentations were presented at a three day workshop focused on sensor modeling and simulation, and image enhancement, processing, and fusion. The technical sessions emphasized how sensor technology can be used to create visual imagery adequate for aircraft control and operations. Participants from industry, government, and academic laboratories contributed to panels on Sensor Systems, Sensor Modeling, Sensor Fusion, Image Processing (Computer and Human Vision), and Image Evaluation and Metrics