https://aurora.auburn.edu/handle/11200/555 2026-04-13T00:31:08Z https://aurora.auburn.edu/handle/11200/50415 Discrimination experiments with the U.S. Army's standard metal detector [1] Discrimination experiments with the U. S. Army's standard hand-held metal detector (AN/PSS-12) are described. An appendix describes the functioning of the device as a metal detector, and the body of the paper discusses modifications to the device necessary to carry out the discrimination experiments. Half of the mines in a large blind test grid were correctly identified with nearly zero false alarms, but the false alarm rate increased substantially for detection probabilities greater than one half. Degradation in performance is attributed to low signal-to-noise ratio from low metallic content mines buried deep in the soil. One measurement was taken with the object centered with respect to the search coils and four more with the object between the concentric search coils in the north, south, east, and west directions. Discrimination performance using all spatial measurements was shown to be superior to that obtained when using only the centered measurement, indicating that spatial measurement diversity is needed to adequately define all the unique modes of a target's polarizability tensor. https://aurora.auburn.edu/handle/11200/50348 The electrostatic characterization of an n-element planar array using the singularity expansion method In this paper, the singularity expansion method (SEM) is used to describe the electrostatic charge distribution on an array of thin linear antennas placed in a uniform electric field. The SEM, which has primarily been used to analyze transient scattering problems, decomposes the electromagnetic interaction process into various quantities such as singularities and modes. Using the SEM, the step plane wave induced transient current on the array is expanded in terms of its singularities (poles) in the Laplace transform (complex frequency domain.) The continuity equation is applied to the induced current expression to obtain the transient charge. The electrostatic charge distribution on the array is found by using the final value theorem on the transient charge expression. It is well known that the SEM factorization of a single linear element reveals that a single pole exists in the fundamental resonance region (near omega L/c = pi, where L is the length of the scatterer). For a two-element array, two poles are observed in the fundamental resonance region. This trend continues such that an n-element array has n poles in the fundamental resonance region. Associated with each pole is a unique modal current and corresponding charge distribution. For example, one of the two fundamental resonance region poles of the two-element array produces half-wavelength sinusoidal current distributions whose directions are the same on one scatterer but opposite on the other. The remaining fundamental resonance region pole produces half-wavelength sinusoidal current distributions whose directions are the same on both scatterers. Corresponding to each mode is a coupling coefficient which determines how much a particular mode couples into the response. A generalization of these results for an n-element array will be given. Furthermore, the electric polarizability is derived in terms of the SEM electric charge description. The value of this research lies in the elegance and strength of the SEM to factor a problem into various quantities which depend on different variables of the problem. By using the SEM to analyse the n-element planar array, a much deeper comprehension of the fundamental aspects of the electrostatic interaction process is achieved. https://aurora.auburn.edu/handle/11200/49986 Estimating the Center of Rotation of Tomographic Imaging Systems with Limited Projections For a tomographic imaging system, image reconstruction quality is highly correlated with accurate determination of the true center of rotation (COR) location. A significant center offset error will introduce ringing, streaking, or other artifacts into the reconstruction, while smaller COR error will cause blurring of the image. Well known COR correction techniques including image registration, center of mass calculation, or reconstruction evaluation work well under certain conditions. However, some conditions, e.g. parallel projections or no tilt in the sensor plane, are often violated in practical situations. Furthermore, limited projections will introduce extra stripe artifacts into the reconstruction that reduce the effectiveness of many COR correction techniques that are sensitive to noise. In this paper, we propose a revised variance-based algorithm to find the correct COR position automatically. The algorithm was tested on phantom and actual cases separately, and the results show improved performance. https://aurora.auburn.edu/handle/11200/49045 AU Smart Cart Senior Design Project Report Fall 2012 Team 3 consists of six members working together to design and build a fully autonomous shopping cart. The purpose of the cart is to perform as a personal shopping assistant to the user as he/she shops in different environments. The project must be able to meet the following requirements in order to be considered a success: • Follow the user and maintain a safe distance • Perform as a cart by carrying a fair amount of objects inside • Respond to voice commands such as: stop and go • Respond to hand gestures As a result from a great deal of hard work put in by each member this semester the team has been successful in developing a working product. The AU SmartCart meets all the requirements set by the team and operates safely and accordingly to all available regulations. In a day and age when humans are becoming increasingly lazy a robotic shopping cart is just the ticket for your everyday shopping desires. This product can be targeted to everyone from lazy young college students, which are too busy text messaging to merely push a cart, all the way up to older citizens that are unable to do so. For a successful company this project could prove to be a very good investment. The endless possibility of potential clientele would leave a company with a wide range of opportunities to cash in on its investment. Overall the AU SmartCart is a wonderful piece of equipment and should prove to be both useful and profitable for any company willing to invest.