+publisher:"Colorado State University" +contributor:("Pinaud, Oliver")

Colorado State University

1. Waddington, Chad. Synthetic aperture source localization.

Degree: PhD, Mathematics, 2018, Colorado State University

URL: http://hdl.handle.net/10217/191271

The detection and localization of sources of electromagnetic (EM) radiation has many applications in both civilian and defense communities. The goal of source localization is to identify the geographic position of an emitter of some radiation from measurements of the elds that the source produces. Although the problem has been studied intensively for many decades much work remains to be done. Many state-of-the-art methods require large numbers of sensors and perform poorly or require additional sensors when target emitters transmit highly correlated waveforms. Some methods also require a preprocessing step which attempts to identify regions of the data which come from emitters in the scene before processing the localization algorithm. Additionally, it has been proven that pure Angle of Arrival (AOA) techniques based on current methods are always suboptimal when multiple emitters are present. We present a new source localization technique which employs a cross correlation measure of the Time Dierence of Arrival (TDOA) for signals recorded at two separate platforms, at least one of which is in motion. This data is then backprojected through a Synthetic Aperture Radar (SAR)-like process to form an image of the locations of the emitters in a target scene. This method has the advantage of not requiring any a priori knowledge of the number of emitters in the scene. Nor does it rest on an ability to identify regions of the data which come from individual emitters, though if this capability is present it may improve image quality. Additionally we demonstrate that this method is capable of localizing emitters which transmit highly correlated waveforms, though complications arise when several such emitters are present in the scene. We discuss these complications and strategies to mitigate them. Finally we conclude with an overview of our method's performance for various levels of additive noise and lay out a path for advancing study of this new method through future work. Advisors/Committee Members: Cheney, Margaret (advisor), Pinaud, Oliver (committee member), Mueller, Jennifer (committee member), Given, James (committee member), Yang, Liuqing (committee member).

Subjects/Keywords: synthetic aperture radar; source localization

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APA (6^th Edition):

Waddington, C. (2018). Synthetic aperture source localization. (Doctoral Dissertation). Colorado State University. Retrieved from http://hdl.handle.net/10217/191271

Chicago Manual of Style (16^th Edition):

Waddington, Chad. “Synthetic aperture source localization.” 2018. Doctoral Dissertation, Colorado State University. Accessed April 13, 2021. http://hdl.handle.net/10217/191271.

MLA Handbook (7^th Edition):

Waddington, Chad. “Synthetic aperture source localization.” 2018. Web. 13 Apr 2021.

Vancouver:

Waddington C. Synthetic aperture source localization. [Internet] [Doctoral dissertation]. Colorado State University; 2018. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/10217/191271.

Council of Science Editors:

Waddington C. Synthetic aperture source localization. [Doctoral Dissertation]. Colorado State University; 2018. Available from: http://hdl.handle.net/10217/191271

2. Murthy, Rashmi. Bayesian approach to the anisotropic EIT problem and effect of structural changes on reconstruction algorithm using 2-D D-bar algorithm.

Degree: PhD, Mathematics, 2018, Colorado State University

URL: http://hdl.handle.net/10217/191473

Electrical Impedance Tomography (EIT) is a relatively new imaging technique that is non-invasive, low-cost, and non-ionizing with excellent temporal resolution.In EIT, the unknown electrical conductivity in the interior of the medium is determined from the boundary electrical measurements. In this work, we attempt to find a direct reconstruction algorithm to the anisotropic EIT problem based on the well-known Calderón's method. The non-uniqueness of the inverse problem is dealt with assuming that the directions of anisotropy are known. We utilize the quasi-conformal map in the plane to accomplish Calderóns approach. Additionally, we derive a probability distribution for the anisotropic conductivity values using a Bayesian formulation, where the direction of anisotropy is encoded as the prior information. We show that this results in the generalized Tikhonov regularization, where the prior information about the direction of anisotropy is incorporated in the regularization operator. The computations of the anisotropic EIT problem using the Bayesian formulation is conducted on simulated data and the resulting reconstructions for the data are shown. Finally, the work of this thesis is concluded by implementing dynamic changes in boundary of a human data during respiration process successfully in the D-bar algorithm. Advisors/Committee Members: Mueller, Jennifer L. (advisor), Cheney, Margaret (committee member), Pinaud, Oliver (committee member), Buchanan, Kristen (committee member).

…Mathematics at Colorado State University focuses on the 2-D thoracic imaging. This is accomplished… …EIT lab at Colorado State University, the ACE1 EIT machine is used to collect experimental…

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Murthy, R. (2018). Bayesian approach to the anisotropic EIT problem and effect of structural changes on reconstruction algorithm using 2-D D-bar algorithm. (Doctoral Dissertation). Colorado State University. Retrieved from http://hdl.handle.net/10217/191473

Chicago Manual of Style (16^th Edition):

Murthy, Rashmi. “Bayesian approach to the anisotropic EIT problem and effect of structural changes on reconstruction algorithm using 2-D D-bar algorithm.” 2018. Doctoral Dissertation, Colorado State University. Accessed April 13, 2021. http://hdl.handle.net/10217/191473.

MLA Handbook (7^th Edition):

Murthy, Rashmi. “Bayesian approach to the anisotropic EIT problem and effect of structural changes on reconstruction algorithm using 2-D D-bar algorithm.” 2018. Web. 13 Apr 2021.

Vancouver:

Murthy R. Bayesian approach to the anisotropic EIT problem and effect of structural changes on reconstruction algorithm using 2-D D-bar algorithm. [Internet] [Doctoral dissertation]. Colorado State University; 2018. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/10217/191473.

Council of Science Editors:

Murthy R. Bayesian approach to the anisotropic EIT problem and effect of structural changes on reconstruction algorithm using 2-D D-bar algorithm. [Doctoral Dissertation]. Colorado State University; 2018. Available from: http://hdl.handle.net/10217/191473

3. Chandramohan, Rajbharath. Hardware implementation and design space exploration for Wave 2D and Jacobi 2D stencil computations.

Degree: MS(M.S.), Electrical and Computer Engineering, 2017, Colorado State University

URL: http://hdl.handle.net/10217/181355

Hardware accelerators are highly optimized functional blocks designed to perform specific tasks from the CPU at a higher performance. We developed a hardware accelerator for Jacobi 2D and Wave 2D algorithms, two computations with a stencil pattern. They are used in a lot of scientific applications in the field of acoustics, electro magnetics and Fluid dynamics. These problems have large problem sizes, memory limitations and bandwidth constraints that result in long run times on large problems. Hence, an approach which increases the performance of these problems that reduces bandwidth requirement is necessary. We developed analytical models depicting the performance, Bandwidth and Area models for the Wave 2D algorithm and Jacobi 2D algorithm and solved them for the optimal solution using posynomials and positivity property in MATLAB and using Excel Solver. We split the computation into two levels of tiling. The first level called passes is a rectangular prism that runs through the 3-D iteration space. Each pass is mapped to a grid of processing elements(PEs) in the hardware accelerator. The second level of tiling splits the vertical prism into smaller prisms executed by a single PE. These optimizations are implemented in Verilog using Altera Quartus and simulated using ModelSIM. Results from ModelSIM provides an accurate model and an experimental verification of the design. We also achieved improved performance and lower bandwidth. Advisors/Committee Members: Rajopadhye, Sanjay (advisor), Pinaud, Oliver (committee member), Pasricha, Sudeep (committee member).

Subjects/Keywords: Jacobi 2D; stencil; hardware accelerator; Wave 2D; optimization

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Chandramohan, R. (2017). Hardware implementation and design space exploration for Wave 2D and Jacobi 2D stencil computations. (Masters Thesis). Colorado State University. Retrieved from http://hdl.handle.net/10217/181355

Chicago Manual of Style (16^th Edition):

Chandramohan, Rajbharath. “Hardware implementation and design space exploration for Wave 2D and Jacobi 2D stencil computations.” 2017. Masters Thesis, Colorado State University. Accessed April 13, 2021. http://hdl.handle.net/10217/181355.

MLA Handbook (7^th Edition):

Chandramohan, Rajbharath. “Hardware implementation and design space exploration for Wave 2D and Jacobi 2D stencil computations.” 2017. Web. 13 Apr 2021.

Vancouver:

Chandramohan R. Hardware implementation and design space exploration for Wave 2D and Jacobi 2D stencil computations. [Internet] [Masters thesis]. Colorado State University; 2017. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/10217/181355.

Council of Science Editors:

Chandramohan R. Hardware implementation and design space exploration for Wave 2D and Jacobi 2D stencil computations. [Masters Thesis]. Colorado State University; 2017. Available from: http://hdl.handle.net/10217/181355

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