Advanced search options

Advanced Search Options 🞨

Browse by author name (“Author name starts with…”).

Find ETDs with:

in
/  
in
/  
in
/  
in

Written in Published in Earliest date Latest date

Sorted by

Results per page:

Sorted by: relevance · author · university · dateNew search

You searched for +publisher:"University of Notre Dame" +contributor:("Alan C Seabaugh , Committee Chair"). Showing records 1 – 2 of 2 total matches.

Search Limiters

Last 2 Years | English Only

No search limiters apply to these results.

▼ Search Limiters


University of Notre Dame

1. Baoyang Deng. Bifurcations and Symmetries of Optimal Solutions for Distributed Robotic Systems</h1>.

Degree: Aerospace and Mechanical Engineering, 2011, University of Notre Dame

In this thesis, we consider the motion planning problem for a symmetric distributed system which consists of a group of autonomous mobile robots operating in a two-dimensional obstacle-free environment. Each robot has a predefined initial state and final state and the problem is to find the optimal path between two states for every robot. The path is optimized with respect to the control effort and the deviation from a desired formation. Due to scaling issues, it becomes more and more difficult and sometimes infeasible to numerically find solutions to the problem as the number of robots increases. One goal of this thesis is to exploit symmetries in distributed control systems to reduce the computational effort to determine solutions for optimal control of such systems. One way to characterize a distributed system is that it is a control system in which the state space is naturally decomposed into multiple subsystems, each of which typically only interacts with a limited subset of the other subsystems. A symmetric distributed system can be defined when the subsystems are diffeomorphically related. The optimal control problem for distributed systems may not scale well with the size of the overall system; hence, our efforts are directed toward exactly solving the optimization problem for large scale systems by working with a reduced order model that is determined by considering invariance properties with respect to certain group actions of the governing equations of the overall system. This thesis also studies bifurcations and multiple solutions of the optimal control problem for mobile robotic systems. While the existence of multiple local solutions to a nonlinear optimization problem is not unexpected, the nature of the solutions are such that a relatively rich and interesting structure is present, which potentially could be exploited for controls purposes. The bifurcation parameter is the relative weight given to penalizing the deviation from the desired formation versus control effort. Numerically it is shown that as this number varies, bifurcations of solutions are obtained. Theoretic results of this paper relate to the symmetric properties of these bifurcations and the number and existence of multiple solutions for large and small values of the bifurcation parameter. Understanding the existence and nature of multiple solutions for optimization problems of this type is also of practical importance due to the ubiquity of gradient-based optimization methods where the search method will typically converge to the nearest local optimum. Advisors/Committee Members: Bill Goodwine, Committee Chair, Alan C Seabaugh , Committee Chair, John E Renaud, Committee Member, Mihir Sen, Committee Member, Panos Antsaklis , Committee Member.

Subjects/Keywords: symmetry; distributed system; Bifurcation

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

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

APA (6th Edition):

Deng, B. (2011). Bifurcations and Symmetries of Optimal Solutions for Distributed Robotic Systems</h1>. (Thesis). University of Notre Dame. Retrieved from https://curate.nd.edu/show/sf268338x32

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Deng, Baoyang. “Bifurcations and Symmetries of Optimal Solutions for Distributed Robotic Systems</h1>.” 2011. Thesis, University of Notre Dame. Accessed September 24, 2020. https://curate.nd.edu/show/sf268338x32.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Deng, Baoyang. “Bifurcations and Symmetries of Optimal Solutions for Distributed Robotic Systems</h1>.” 2011. Web. 24 Sep 2020.

Vancouver:

Deng B. Bifurcations and Symmetries of Optimal Solutions for Distributed Robotic Systems</h1>. [Internet] [Thesis]. University of Notre Dame; 2011. [cited 2020 Sep 24]. Available from: https://curate.nd.edu/show/sf268338x32.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Deng B. Bifurcations and Symmetries of Optimal Solutions for Distributed Robotic Systems</h1>. [Thesis]. University of Notre Dame; 2011. Available from: https://curate.nd.edu/show/sf268338x32

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


University of Notre Dame

2. Qin Zhang. Interband Tunnel Transistors</h1>.

Degree: Electrical Engineering, 2009, University of Notre Dame

Interband tunnel transistors have been attracting increasing attention because of their potential to achieve subthreshold swings below the 60 mV/decade thermionic limit, and realize high performance and low power dissipation simultaneously. This work explores the design and modeling of semiconducting and graphene nanoribbon-based tunnel transistors, to understand the performance measures and guide the experimental development. Experiments in the formation of Ge interband junctions are also described. Analytic expressions for Zener tunneling in one-, two-, and three-dimensional semiconductors are derived to establish the guidelines for tunnel transistor design. An analytic expression is derived, showing that the subthreshold swing of interband tunnel transistors is a function of the gate-to-source voltage and can be less than the thermionic limit of 60 mV/decade in MOSFET. Based on this expression, a new fully-depleted interband tunnel transistor structure is proposed and designed. The low subthreshold swing is verified by Synopsys TCAD simulation. Germanium interband tunnel transistors are shown by simulation to exhibit improved on-state performance vs. Si, because of the smaller bandgap and effective mass. To realize the proposed Ge interband tunnel transistor, a rapid melt growth process was developed to form submicron p+n+ Ge tunnel junctions. Transmission electron microscopy (TEM) reveals the regrown film and a contact microstructure consistent with the Al-Ge phase diagram. Negative differential resistances are observed which indicate the junction was abrupt heavily-doped. A graphene nanoribbon (GNR) tunnel transistor is first proposed and modeled analytically by quasi-1D Poisson equation. An improved numerical model is developed that treates energy-dependent transmission coefficients, direct source-to-drain tunneling, and self-consistent channel electrostatics. Graphene nanoribbons have a width-tunable bandgap and ultra-thin body layer, which is especially favorable for tunnel transistor applications. It is shown by simulation that the GNR tunnel transistors at the long channel limit can operate at 0.1 V with an ultra-low subthreshold swing of 2.8 mV/decade, but the subthreshold swing and off-state current are degraded at short channel length due to direct source-to-drain tunneling. Smaller ribbon widths (down to a certain limit) can significantly improve the off-state behavior without considerably affecting the on-state current density and speed. For 20 nm channel length, GNR tunnel transistors with ribbon width of 2 and 3 nm can achieve high performance and low operating power simultaneously, meeting 2012 ITRS targets. Advisors/Committee Members: Thomas Kosel, Committee Member, Debdeep Jena , Committee Member, Gary Bernstein , Committee Member, Alan C. Seabaugh, Committee Chair.

Subjects/Keywords: Zener tunneling; graphene; tunnel transistor

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

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

APA (6th Edition):

Zhang, Q. (2009). Interband Tunnel Transistors</h1>. (Thesis). University of Notre Dame. Retrieved from https://curate.nd.edu/show/5h73pv65c7m

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Zhang, Qin. “Interband Tunnel Transistors</h1>.” 2009. Thesis, University of Notre Dame. Accessed September 24, 2020. https://curate.nd.edu/show/5h73pv65c7m.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Zhang, Qin. “Interband Tunnel Transistors</h1>.” 2009. Web. 24 Sep 2020.

Vancouver:

Zhang Q. Interband Tunnel Transistors</h1>. [Internet] [Thesis]. University of Notre Dame; 2009. [cited 2020 Sep 24]. Available from: https://curate.nd.edu/show/5h73pv65c7m.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Zhang Q. Interband Tunnel Transistors</h1>. [Thesis]. University of Notre Dame; 2009. Available from: https://curate.nd.edu/show/5h73pv65c7m

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.