This thesis presents the design and development of a process to model Very Long Base Line Interferometry (VLBI) aperture synthesis antenna arrays. In line with the Auckland University of Technology (AUT) Institute for Radiophysics and Space Research (IRSR) aims to develop the knowledge, skills and experience within New Zealand, extensive use of existing radio astronomical software has been incorporated into the process namely AIPS (Astronomical Imaging Processing System), MIRIAD (a radio interferometry data reduction package) and DIFMAP (a program for synthesis imaging of visibility data from interferometer arrays of radio telescopes). This process has been used to model various antenna array configurations for two proposed New Zealand sites for antenna in a VLBI array configuration with existing Australian facilities and a passable antenna at Scott Base in Antarctica; and the results are presented in an attempt to demonstrate the improvement to be gained by joint trans-Tasman VLBI observation. It is hoped these results and process will assist the planning and placement of proposed New Zealand radio telescopes for cooperation with groups such as the Australian Long Baseline Array (LBA), others in the Pacific Rim and possibly globally; also potential future involvement of New Zealand with the SKA. The developed process has also been used to model a phased building schedule for the SKA in Australia and the addition of two antennas in New Zealand. This has been presented to the wider astronomical community via the Royal Astronomical Society of New Zealand Journal, and is summarized in this thesis with some additional material. A new measure of quality (“figure of merit”) for comparing the original model image and final CLEAN images by utilizing normalized 2-D cross correlation is evaluated as an alternative to the existing subjective visual operator image comparison undertaken to date by other groups. This new unit of measure is then used in the presentation of the results to provide a quantative comparison of the different array configurations modelled. Included in the process is the development of a new antenna array visibility program which was based on a Perl code script written by Prof Steven Tingay to plot antenna visibilities for the Australian Square Kilometre Array (SKA) proposal. This has been expanded and improved removing the hard coded fixed assumptions for the SKA configuration, providing a new useful and flexible program for the wider astronomical community. A prototype user interface using html/cgi/perl was developed for the process so that the underlying software packages can be served over the web to a user via an internet browser. This was used to demonstrate how easy it is to provide a friendlier interface compared to the existing cumbersome and difficult command line driven interfaces (although the command line can be retained for more experienced users).

Field programmable gate arrays are a class of integrated circuit that enable logic functions and interconnects to be programmed in almost real time. They can implement fine grained parallel computing architectures and algorithms in hardware that were previously the domain of custom VLSI. Field programmable gate arrays have shown themselves useful at exploiting concurrency in a range of applications such as text searching, image processing and encryption. When coupled with a microprocessor, which is more suited to computation involving complex control flow and non time critical requirements, they form a potentially versatile platform commonly known as a Reconfigurable Computer. Reconfigurable computing applications have traditionally had the exclusive use of the field programmable gate array, primarily because the logic densities of the available devices have been relatively similar in size compared to the application. But with the modern FPGA expanding beyond 10 million system gates, and through the use of dynamic reconfiguration, it has become feasible for several applications to share a single high density device. However, developing applications that share a device is difficult as the current design flow assumes the exclusive use of the FPGA resources. As a consequence, the designer must ensure that resources have been allocated for all possible combinations of loaded applications at design time. If the sequence of application loading and unloading is not known in advance, all resource allocation cannot be performed at design time because the availability of resources changes dynamically. The use of a runtime resource allocation environment modelled on a classical software operating system would allow the full benefits of dynamic reconfiguration on high density FPGAs to be realised. In addition to runtime resource allocation, other services provided by an operating system such as abstraction of I/O and inter-application communication would provide additional benefits to the users of a reconfigurable computer. This could possibly reduce the difficulty of application development and deployment. In this thesis, an operating system for reconfigurable computing that supports dynamically arriving applications is presented. This is achieved by firstly developing the abstractions with which designers implement their applications and a set of algorithm requirements that specify the resource allocation and logic partitioning services. By combining these, an architecture of an operating system for reconfigurable computing can be specified. A prototype implementation on one platform with multiple applications is then presented which enables an exploration of how the resource allocation algorithms interact amongst themselves and with typical applications. Results obtained from the prototype include the measurement of the performance loss in applications, and the time overheads introduced due to the use of the operating system. Comparisons are made with programmable logic applications run with and without the operating system. The results show that the overheads are reasonable given the current state of the technology of FPGAs. Formulas for predicting the user response time and application throughput based on the fragmentation of an FPGA are then derived. Weaknesses are highlighted in the current design flows and the architecture of current FPGAs must be rectified if an operating system is to become main-stream. For the tool flows this includes the ability to pre-place and pre-route cores and perform high speed runtime routing. For the FPGAs these include an optimised network, a memory management core, and a separate layer to handle dynamic routing of the network. / thesis (PhD)--University of South Australia, 2005.

Thesis (Ph. D.)--University of Texas at Dallas, 2006. / Includes vita. Includes bibliographical references (leaves 173-178).

Denna rapport presenterar en metod som möjliggör bestämning av bredbandiga signalers infallsvinklar. Studien är gjord i Matlab där infallande signaler samplades med ett antal sensorer utplacerade ekvidistant på en rätlinje. Den samplade informationen viktades sedan med konstanter framtagna med en konvex optimeringsrutin för att bilda en vinkelberoende utsignal. Rutinerna testades för insignaler med ett få antal frekvenser och gav för alla testade insgnaler en mycket bra bestämmning av infallsvinklen. Studien visar även att det är möjligt att göra systemet mer robust mot störningar i sensorernas positioner genom att ställa kriterier på den konvexa optimerings rutinen.

Digital Clay is a tactile array of linear fluidic actuators which provide distributed sensing and position control through the use of an embedded position sensor. The actuator implementation is achieved by two-way hydraulically-driven pistons which are integrated with computer controlled valves. Each actuator is connected to an underlying base plate which is in fluidic communication with high and low pressure reservoirs. The research focuses on the aspects of the fluidics necessary to operate the actuators and control actuation of Digital Clay. The main objectives of this work are the characterization of the fluid flow through the system and the design and implementation of an embedded inductance-based position sensor. Each actuator in Digital Clay is individually addressable and is controlled through the use of a closed-loop proportional integral controller with position feedback from the embedded inductance-based sensor. Also presented in this work is the characterization of an individual fluidic actuator and the realization of a 5x5 tactile array of actuators.

Here choose wedge-shaped fiber, which have sample shape, low manufacture cost and time, to manufacture wedge-shaped fiber array in the paper. In order to reduce cost, it depends on change and reduce manufacture process steps.

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 212-225). Available also in a digital version from Dissertation Abstracts.

Thesis (M.S. in Engineering Science)--Naval Postgraduate School, December 2003. / Thesis advisor(s): David C. Jenn, Roberto Cristi. Includes bibliographical references (p. 95). Also available online.

Not available / text

Acoustic Receiving Line Arrays are critical tools for measuring the acoustic properties of any oceanographic region. Vertical, horizontal, and combinations of the two array configurations allow us to measure acoustic propagation, bottom characteristics through inversion, and ambient noise. These properties are vitally important for effective implementation of any passive or active detection system in both shallow and deep water environments. Measurement systems must be designed with flexibility since the exact array design that yields the best signal processing results is not known prior to a survey. Flexibility, in this case, refers to large numbers of hydrophones, higher sample rates for greater bandwidth, and longer recording time to facilitate experimentation at each survey site. Repeated deployment and recovery of such a system demands a battery powered autonomous design that can be deployed and recovered from available research vessels at sea. Conventional deep ocean analog array cable designs, while power efficient, become physically challenging in size and weight when the sensor count exceeds 100 and array lengths remain in the 100s of meters. The purpose of this thesis is to detail the design, development, and testing of a pressure tolerant full ocean depth rated prototype acoustic line array with digital telemetry of all hydrophone data from the sensors to the recording system. The design is to support up to 300 hydrophones each with a maximum sample rate of 4 kHz and a per sensor power requirement of ¾ of a watt. Lower sensor counts will allow higher sample rates to be used based on available telemetry bandwidth. A single element of a line array was built and tested at the University of Texas at Austin Applied Research Laboratories and it was used to demonstrate real-time telemetry and recording of acoustic hydrophone data. / text