The Schlumberger array, or Schlumberger, was one of the first resistance arrays to be used to detect buried archaeological features. The early work used fixed probes and widely spaced traverses. Recent simulation work, ýhowever, suggested that the array should give improved resolution and depth penetration over the Twin-Probe array. This thesis is an attempt to operationalise the Schlumberger for use in archaeological prospection. This has been achieved via a co-ordinated use of laboratory simulation and-field studies. Initial fieldwork in England suggested. that the. - use of point electrodes created response patterns that were dependent upon the relative direction of linear targets. This was verified using a simulation tank modified to represent field procedure. The recognition of this response, therefore, required each survey area to be surveyed twice. The re-survey requires the two current probes to be positioned at right angles to the original survey points. The Schlumberger was then used in a battery of methods to investigate the problem of the archaeological interpretation of- small, discrete scatters of ceramic sherds that cover the landscape in Greece. The research has indicated a variation of intra-site patterning that may be significant to the function of these sites. Overall, the results suggest that the relationship between the 'site' and its environment is a complex one, one that can be oversimplified when the ceramic evidence is viewed in isolation. The Schlumberger indicated possible structural elements within some of these sites.

Sound generation and radiation properties are studied of full-scale tactical jet engine noise. This is motivated by the high sound exposure levels from jet noise, particularly for tactical engines. Acoustic source reconstruction methods are implemented computationally on existing jet noise data. A comparative study is performed using numerical simulations to understand the capabilities of more advanced beamforming methods to successfully estimate the source properties of a distributed, partially correlated source distribution. The properties and limitations of each beamforming method are described. Having validated the methods, beamforming with regularization—via the Hybrid Method—is implemented on linear array measurements near an installed tactical engine. A detailed analysis of the correlation and coherence properties associated with the phased array measurements guides the implementation of the beamforming. When the measurements are used as inputs to the beamforming, they produce partially correlated, distributed sources in a full-order model representation. A processing technique is also implemented that increases the usable bandwidth of the array measurements to almost an order of magnitude above the array design frequency. To more appropriately study the equivalent sources, a decomposition technique is designed and implemented to create a reduced-order wavepacket model of the jet noise. The wavepacket model is modular and scalable to allow for the efficient characterization of similar jet noise measurements. It is also appropriate for its physical significance, as wavepackets are attributed to the turbulent flow as well as the hydrodynamic and acoustic properties of the radiation. The reduced order model can estimate the levels and coherence properties of the acoustic radiation and represents a significant step towards a complete jet noise prediction model.

Sound generation and radiation properties are studied of full-scale tactical jet engine noise. This is motivated by the high sound exposure levels from jet noise, particularly for tactical engines. Acoustic source reconstruction methods are implemented computationally on existing jet noise data. A comparative study is performed using numerical simulations to understand the capabilities of more advanced beamforming methods to successfully estimate the source properties of a distributed, partially correlated source distribution. The properties and limitations of each beamforming method are described. Having validated the methods, beamforming with regularization”via the Hybrid Method”is implemented on linear array measurements near an installed tactical engine. A detailed analysis of the correlation and coherence properties associated with the phased array measurements guides the implementation of the beamforming. When the measurements are used as inputs to the beamforming, they produce partially correlated, distributed sources in a full-order model representation. A processing technique is also implemented that increases the usable bandwidth of the array measurements to almost an order of magnitude above the array design frequency. To more appropriately study the equivalent sources, a decomposition technique is designed and implemented to create a reduced-order wavepacket model of the jet noise. The wavepacket model is modular and scalable to allow for the efficient characterization of similar jet noise measurements. It is also appropriate for its physical significance, as wavepackets are attributed to the turbulent flow as well as the hydrodynamic and acoustic properties of the radiation. The reduced order model can estimate the levels and coherence properties of the acoustic radiation and represents a significant step towards a complete jet noise prediction model.

<p> The philosophy of parallel processing within computers is discussed and a word-organized memory array is described in which each word location includes an independent, autonomous, arithmetic and logical processor. Several examples of computations within the memory are suggested and application in the solution of potential field problems is discussed. The concept of the arithmetic memory cell is introduced and applied in a design outline for a digital instrument capable of measuring correlation functions and mean values of fluctuating voltages. </p> / Thesis / Master of Engineering (ME)

No / A new approach in achieving beam steering in array antenna is introduced using the genetic algorithm optimization. The binary switching technique uses simple binary ON/OFF diodes placed in the feeding network of the array element to achieve beam steering. Constantly feeding the driven element and continuous binary variation of the ON/OFF state of each parasitic array elements which determines its conducting ability defines a beam steering angle. Each beam steered angle is distinguished by series of binary combination determined by the genetic algorithm. A uniform circular array antenna consisting of 13 elements is used to implement this technique. The simulation and result analysis of the binary switched array is presented with several beam steering angles scanned.

No description available.

A 3D Finite Element Boundary Integral technique (FE-BI) using mixed-order tangential vector finite elements (TVFE?s) is presented. This technique is used to design two wide band antennas and an ultra wideband (UWB) antenna array. Tetrahedral elements are used for domain discretization because they offer higher flexibility when simulating complex structures. A set of hierarchical mixed-order TVFE?s up to and including order 2.5 is implemented. Hierarchical mixed-order TVFE?s accurately simulate regions with high and low field variations. They also guarantee tangential field continuity across element boundaries and suppress spurious modes. The efficacy of the technique has been tested on two different wide band antennas and an UWB array. The first antenna is designed for automotive applications and covers GPS, GSM, XM, and PCS bands (0.8?3.35 GHz). The second antenna is a double sided rounded bowtie antenna (DSRBA) for UWB communication (3.1-10.6 GHz). The third design is a DSRBA array. For validation purposes, the antennas are also simulated using a commercially available high frequency electromagnetic simulation software, HFSS. Results regarding antenna parameters such as return loss, radiation pattern, and gain are also given.

This work can be viewed in three separate sections, each of which build off of the prior. The first part of this study examined the flow in a 1/16th scale calandria test section based on a typical CANDU moderator layout. The experiments utilized forced flow supplied to the vessel and electrical heated rods to mimic the heat flow from calandria tubes. The size of the vessel, flow rates, and power levels were used to scale the experiments such that the provided representative temperature fields. The temperature field inside the vessel was measured and shown to compare well with CFD predictions over a wide range of inlet conditions and power levels. Additionally, this work addressed the scaling distortions in the experiment which occurred due to physical limitations when performing experiments at 1/16 scale (e.g., a smaller number of heater rods with a larger diameter were used in the experiment because at 1/16-scale direct fabrication of 390 fuel channel simulators is not feasible). The work proposed the H factor addition to the Ar. This additional scaling criteria was shown to better maintain the flow regimes expected CANDU moderators by taking into account distortions introduced by surface heating instead of volumetric heating in addition to the reduction in total number of tubes. While this work involved forced convective flows at the inlet of the vessel, in some regions of the calandria buoyancy induced forces were sufficiently high such that these phenomena altered the direction and magnitude of the flows as compared to purely forced convective behavior. Hence further work, discussed below, was initiated to better understand and measure these local phenomena where buoyancy forces are of similar magnitude as those of forced convection. Such local conditions we have terms mixed convection regime for the purposes of this thesis. The second part of this work further examined the mixed convection between a subset of the CANDU calandria tubes, namely how does a lower tube effect the mixed convection heat transfer of the upper tube in an inline arrangement. To isolate and measure the phenomena with sufficient detail, a small number of tubes was studied and advanced diagnostics such as Particle Image Velocimetry (PIV) and Laser Induced Fluorescence (LIF) were employed. This study combined fluid velocity, temperature and wall temperature measurements with CFD simulations to develop a mechanistic model and understanding of the effect of natural convection plumes from lower elevations on the natural circulation phenomena on an upper cylinder. Superposition of the natural convection phenomena combined with pseudo forced convection effects from the lower elevation cylinder’s plume was used to model the mixed convection phenomena. This model was shown to perform well, with nearly all data being predicted to with +-20% for experiments performed in this work, and experiments in literature. A major finding from the preceding discussion is the importance of the lower elevation plume velocity on the local phenomena on the upper cylinder. The third section further expanded upon the prior two by replacing the lower cylinder with a diffuser nozzle which could provide a forced convective component with accurately defined velocities. Such measurements allow for accurate definition of the local Ri number and allowed full access for instrumentation to observe the velocity fields. The major contribution of this work was a flow regime map that defined the phenomena around a heated cylinder under mixed convection conditions. Additionally, the establishment of a database of fluid temperature and velocity measurements for a wide range of Ri was also developed and used to further validate CFD predictions. / Thesis / Doctor of Philosophy (PhD)

No description available.

No description available.