Dielectric Resonator Antenna and Array Concepts based on Glass, Ceramics and Glass-ceramics

The focus of this work has been the exploration of different concepts of the dielectric resonator antennas. Mainly, a new kind of glass-ceramic material was characterized and used for making different dielectric loaded or dielectric resonator antennas and corresponding arrays based on such radiating elements. The measurements were carried out on different glass-ceramic compositions and showed a permittivity ranging from 21 to 38 with Qf product in the range from 1500 to 10000 GHz. Patch antennas for the GPS band using glass-ceramic loading were successfully fabricated and tested. The transparent property of the non-ceramized glass was used for making transparent antennas in combination with a solar-cell module for future energy-autonomous units. Its functionality was demonstrated with a measured gain of 4 dB. Another novel concept of tilted beam dielectric resonator antenna was also successfully tested. The beam was measured to be tilted at 30◦ from the broadside. The prototype was manufactured by using commonly available alumina substrate material and cutting it with laser, thus providing an easy fabrication method. The tilted dielectric resonator antenna element has also been used to fabricate fixed beam arrays at 0◦, 30◦ and 60◦ beams. This proved the concept of using the tilted beam dielectric resonator antennas for better lower elevation angle coverage. Another major part of the work was concerned with realizing the phased arrays with dielectric resonator antennas as radiating elements. Two phased array demonstrators were fabricated in 1 × 4 configuration. One of the array consisted of liquid crystal based delay lines in inverted microstrip technology. It was fabricated with 10 GHz target frequency and successfully showed steering of the beams in −25◦ and +25◦. The second array was based on Barium Strontium Titanate phase shifters in the metal-insulator-metal configuration. This array used stacked dielectric resonator antennas for a wide bandwidth at center frequency of 8 GHz and showed beam steering of −30◦ and +30◦

Research in progress in applied mathematics, numerical analysis, fluid mechanics, and computer science

This report summarizes research conducted at the Institute for Computer Applications in Science and Engineering in applied mathematics, fluid mechanics, and computer science during the period October 1, 1993 through March 31, 1994. The major categories of the current ICASE research program are: (1) applied and numerical mathematics, including numerical analysis and algorithm development; (2) theoretical and computational research in fluid mechanics in selected areas of interest to LaRC, including acoustics and combustion; (3) experimental research in transition and turbulence and aerodynamics involving LaRC facilities and scientists; and (4) computer science

Recent Advances in Signal Processing

The signal processing task is a very critical issue in the majority of new technological inventions and challenges in a variety of applications in both science and engineering fields. Classical signal processing techniques have largely worked with mathematical models that are linear, local, stationary, and Gaussian. They have always favored closed-form tractability over real-world accuracy. These constraints were imposed by the lack of powerful computing tools. During the last few decades, signal processing theories, developments, and applications have matured rapidly and now include tools from many areas of mathematics, computer science, physics, and engineering. This book is targeted primarily toward both students and researchers who want to be exposed to a wide variety of signal processing techniques and algorithms. It includes 27 chapters that can be categorized into five different areas depending on the application at hand. These five categories are ordered to address image processing, speech processing, communication systems, time-series analysis, and educational packages respectively. The book has the advantage of providing a collection of applications that are completely independent and self-contained; thus, the interested reader can choose any chapter and skip to another without losing continuity

Application of advanced non-destructive testing methods on bridge health assessment and analysis

Bridge structures have an important role in economic, social and environmental aspects of society life. Bridges are also subject to a natural process of deterioration of construction materials, as well as natural and environmental events such as flooding, freezing, thawing etc. Health monitoring and assessment of the structural integrity of bridges have been the focus of engineers and researchers for decades. Currently, the various aspects of bridge health are monitored separately. However, measuring these aspects independently does not give the overall health of the bridge and crucial indicators of structural damage can be neglected. Generally, bridge health assessments take the form of individual NDT (non-destructive techniques) detecting individual defects. However value can be added to these results by combining and comparing the findings of several different NDT surveys. By completing this, a more accurate assessment of bridge health is obtained. This increases confidence in the decision as to whether remedial action is necessary. In this thesis an integrated bridge health monitoring approach is proposed which applies several NDT specifically chosen for bridge health assessments, thus achieving this added value. This method can be used as a part of a comprehensive bridge monitoring strategy as an assessment tool to evaluate the bridges structural health. This approach enables the user of this approach to obtain a detailed structural report on the bridge with all the necessary information pertaining to its’ health, allowing for a fully educated decision to be made regarding whether remedial action is necessary. This research presents the results of the applications of such methods on case studies utilising Ground Penetrating Radar (GPR), IBIS-S technology / system (deflection and vibration detection sensor system with interferometric capability) and Accelerometer sensors. It also evaluates the effectiveness of the adopted methods and technologies by comparing and validating the yielded results with conventional methods (modelling and visual inspection). The research presents and discusses processed data obtained by the above mentioned methods in detail and reports on challenges encountered in setting up and materialising the assessment process. This work also reports on Finite Element Modelling (FEM) of the main case study (Pentagon Road Bridge) using specialist software (SAP2000 and ANSYS) in order to simulate the perceived movement of the bridge under dynamic and static conditions. The analytical results output were compared with results obtained by the applications of the above non-destructive methods. Thus by using these techniques the main aim of this thesis is to develop an integrated model/approach for the assessment and monitoring of the structural integrity and overall functionality of bridges. All the above methods were validated using preliminary case studies (GPR), additional equipment (accelerometers for IBIS-S validation) and additional techniques and information (SAP 2000 and ANSYS were compared to one another and IBIS-S results). All of these techniques were applied on the Pentagon Road Bridge. This bridge was chosen as no information was available regarding its structural composition. Visual inspection showed the external defects of the structure: cracking, moisture ingress and concrete delamination was present in one of the spans of the bridge. The GPR surveys gave the position of the rebars and also signs of moisture ingress at depths of 20cm (confirmed using velocity analysis). IBIS-S gave results for the deflection of the structure. FEM was used to model the behaviour of the bridge assuming no defects. To achieve additional model accuracy the results of the rebar position were input in to the model and it was calibrated using IBIS-S data. The deflection results from the model were then compared to the actual deflection data to identify areas of deterioration. It was found that excessive deflection occurred on one of the spans. It was thus found that all NDT indicated that a particular span was an area of significant deterioration and remedial action should be completed on this section in the near future. Future prediction was also completed by running simulations in ANSYS for increasing crack lengths and dynamic loading. It was found that if there is no remedial action excessive beam bending moments will occur and eventual collapse. The results of this research demonstrated that GPR provided information on the extent of the internal structural defects of the bridge under study (moisture ingress and delamination) whilst IBIS-S technology and Accelerometer sensors permitted measurement of the magnitude of the vibration of the bridge under dynamic and static loading conditions. The results depicted similarities between the FEM results and the adopted non-destructive methods results in location and pattern. This work can potentially contribute towards a better understanding of the mechanical and physical behaviours of bridge structures and ultimately assess their life expectancy and functionality

Abstracts of manuscripts submitted in 1990 for publication

This volume contans the abstracts of manuscripts submitted for publication during calendar year 1990 by the staff and students of the Woods Hole Oceanographic Institution. We identify the journal of those manuscripts which are in press or have been published. The volume is intended to be informative, but not a bibliography. The abstracts are listed by title in the Table of Contents and are grouped into one of our five deparments, Marine Policy Center, Coastal Research Center, or the student category. An author index is presented in the back to facilitate locating specific papers

Ocean Noise

Scientific and societal concern about the effects of underwater sound on marine ecosystems is growing. While iconic megafauna was of initial concern, more and more taxa are being included. Some countries have joined in multi-national initiatives to measure, monitor and mitigate environmental impacts of ocean noise at large, trans-boundary spatial scales. Approaches to regulating ocean noise change as new scientific evidence becomes available, but may also differ by country. The OCEANOISE conference series has provided a platform for the exchange of scientific results, management approaches, research needs, stakeholder concerns, etc. Attendees have represented various sectors, including academia, offshore industry, defence, NGOs, consultants and government regulators. The published articles in the Special Issue cover a range of topics and applications central to ocean noise

A study of the soil pattern, properties and hydrology of a mole and tile-drained, loess-mantled downland in Southland, New Zealand : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University

Dissected, loess-mantled terraces (downlands) are a dominant component of the soil-landscape in Southland, New Zealand and commonly contain soils with dense subsoils that impede drainage. Consequently mole and tile drainage systems, which removes excess soil moisture, are widespread. Alongside agronomic benefits, mole and tile drainage creates problematic secondary effects, including altered stream hydrographs, contaminant transfer into surface water and possible modification of soil properties. Today, water quality and quantity management rely heavily on environmental modelling. Models of soil – water interactions are informed by knowledge of soil hydraulic properties and processes, which is gained from a variety of disciplines, including pedology, soil physics and hydrology. Understanding the properties and processes relevant to mole and tile-drained, slowly permeable loess soils is, thus, criticical for reliable simulations of their water dynamics. Concerningly, this understanding remains elusive. There is a need to better understand the variability in soil properties that regulate water storage, movement and connectivity, as well as the intrinsic and extrinsic controls on water flow pathways. These research gaps were addressed by characterising and monitoring a small, mole and tile-drained basin on a typical Southland sheep farm. Surveying of the soil and loess mantle found vertical differentiation of soil properties was due to contemporary pedogenesis, and soil features inherited from buried loess sheets were important sources of heterogeneity in water-regulating soil properties. Catchment side slopes had greater soil variation relative to the interfluves. Buried loess sheets, which had been exhumed by hillslope procceses, were contributing to the subsoils on the basin slopes whereas the soils on the interfluves were formed solely into the uppermost loess sheet. The findings confirm that understanding the soil-geomorphology of loess-mantled downlands is important for improving soil – landscape models, characterising soil spatial variability and producing more accurate soil maps. Ground penetrating radar (GPR) was effective at identifying and mapping mole channels, thus allowing drainage density to be quantified and the mole network to be characterised. It demonstrated that the mole networks had non-systematic patterns and most likely were multi-generational. Ground truthing during the GPR survey showed mole channels were in good condition even after 30 + years without maintenance. From a survey of soil hydraulic properties it was apparent that the mole fracture network created when moles were installed had not persisted. The finding has implications for hydrological and water quality modelling, as preferential flow via the fracture network is commonly considered to be the major route for rapid water and contaminant transfer into moles. Mole channels were not found to influence soil properties directly; however, it was discovered that surface saturated hydraulic conductivity (Ksat) was controlled by antecedent soil moisture state in parts of the landscape where perched water tables (PWT) persisted. This was hypothesised to occur by priming of the macropore network when capillary rise from a PWT removed air pockets, signalling a potential indirect influence of drainage systems on Ksat. A water balance analysis refuted a common assumption of negligible deep drainage in slowly permeable loess, with or without artificial drainage. Deep drainage varied between events as well as seasonally and occurred via piston flow through the fragipan and underlying loess mantle. Runoff (tile and overland flow) responses to rainfall events could be discriminated by thresholds of precipitation volume and/or intensity, depending on antecedent soil moisture state (dry or wet). Infiltration-excess overland flow was the most common form of surface runoff, consistent with the low surface infiltration rates estimated from infiltration experiments. A corollary is that shifts in the distribution of precipitation intensity with climate change could change the overland flow component of the water balance of this landscape. Tile flow from small events was predominantly sourced from the interfluves and upper hollow. As events became larger, the source area expanded until most of the catchment was contributing to tile flow. When considering the mitigation of contaminant transfers to surface water, winter and spring should be be key time periods, and the upper hollow and interfluves key locations, on which to focus. Soil moisture spatial patterns appeared to be influenced by both PWTs and the artificial drainage network and were not well predicted by the topographic wetness index (TWI). In the dry soil moisture state, upslope areas were hydrologically disconnected. With increasing catchment wetness, hydrological connectivity expanded from the lower hollow to the PWTs at the mid- to upper hollow, and eventually up to the interfluve PWTs. Once the hydrological connection between the lower hollow and interfluve had been established, the catchment had completed its transition into the wet state, and the interfluve PWT and mole network became the primary regulator of tile flow. The transition from dry state to wet state soil moisture conditions took about two weeks and began at the lower catchment hollow. Only rainfall periods with exceptional precipitation volumes and intensities connected the slopes, and only when all other parts of the catchment were saturated. There was no evidence that natural interflow, either as matrix or preferential flow, led to hydrological connection. Surface-sourced preferential flow to the tile drain occurred when the soil was in the dry state, but the flux was hydrologically insignificant. The thesis highlights: The need for significant sources of soil variation associated with loess stratigraphy to be represented in soil classification and mapping; that, while there was no un-drained control in the experimental set-up, the effects of the artificial drainage network appear to be profound and must be considerd in hydrological-contaminant modelling; and finally, that several common assumptions about flow pathways (i.e., mole channel fracture networks, negligible deep drainage, significant natural interflow, insignificant overland flow) in artificially drained, low permeability loess may be inappropriate and, consequently, their use in modelling in support of management and mitigation needs careful evaluation

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

Evaluation of the flail space model utilizing event data recorder technology

Developed in the early 1980\u27s, the flail space model has become the standard method for estimating occupant risk in full-scale crash tests involving roadside safety features. The widespread availability of airbags and increased seat belt usage rates in today\u27s vehicle fleet, however, raise serious questions regarding the validity of the model. Recent implementation of Event Data Recorder (EDR) technology in a number of late model vehicles presents a different perspective on the assessment of the validity of occupant risk based on the flail space model. EDRs are capable of electronically recording data such as vehicle speed, brake status and throttle position just prior to and during an accident. Of particular interest is the EDR\u27s ability to document the deceleration of a vehicle during a collision event. This thesis presents a methodology utilizing EDR data to investigate the capability of the flail space model to predict injury to airbag-restrained occupants. Results of a preliminary analysis are presented based on implementation of the developed methodology on a limited data set. A major part of the analysis is limited to the occupant impact velocity due to complications in estimating the occupant ridedown acceleration from the available EDR data. The longitudinal occupant impact velocity is found to be a good predictor of overall injury, chest injury and, to a lesser extent, lower extremity injury. For the head and upper extremity body region, the longitudinal occupant impact velocity is a weak predictor of injury. In the analyzed data set, the occupant impact velocity is found to be a more significant predictor of overall occupant injury than the occupant ridedown acceleration