Control Theory-Inspired Acceleration of the Gradient-Descent Method: Centralized and Distributed

Mathematical optimization problems are prevalent across various disciplines in science and engineering. Particularly in electrical engineering, convex and non-convex optimization problems are well-known in signal processing, estimation, control, and machine learning research. In many of these contemporary applications, the data points are dispersed over several sources. Restrictions such as industrial competition, administrative regulations, and user privacy have motivated significant research on distributed optimization algorithms for solving such data-driven modeling problems. The traditional gradient-descent method can solve optimization problems with differentiable cost functions. However, the speed of convergence of the gradient-descent method and its accelerated variants is highly influenced by the conditioning of the optimization problem being solved. Specifically, when the cost is ill-conditioned, these methods (i) require many iterations to converge and (ii) are highly unstable against process noise. In this dissertation, we propose novel optimization algorithms, inspired by control-theoretic tools, that can significantly attenuate the influence of the problem's conditioning. First, we consider solving the linear regression problem in a distributed server-agent network. We propose the Iteratively Pre-conditioned Gradient-Descent (IPG) algorithm to mitigate the deleterious impact of the data points' conditioning on the convergence rate. We show that the IPG algorithm has an improved rate of convergence in comparison to both the classical and the accelerated gradient-descent methods. We further study the robustness of IPG against system noise and extend the idea of iterative pre-conditioning to stochastic settings, where the server updates the estimate based on a randomly selected data point at every iteration. In the same distributed environment, we present theoretical results on the local convergence of IPG for solving convex optimization problems. Next, we consider solving a system of linear equations in peer-to-peer multi-agent networks and propose a decentralized pre-conditioning technique. The proposed algorithm converges linearly, with an improved convergence rate than the decentralized gradient-descent. Considering the practical scenario where the computations performed by the agents are corrupted, or a communication delay exists between them, we study the robustness guarantee of the proposed algorithm and a variant of it. We apply the proposed algorithm for solving decentralized state estimation problems. Further, we develop a generic framework for adaptive gradient methods that solve non-convex optimization problems. Here, we model the adaptive gradient methods in a state-space framework, which allows us to exploit control-theoretic methodology in analyzing Adam and its prominent variants. We then utilize the classical transfer function paradigm to propose new variants of a few existing adaptive gradient methods. Applications on benchmark machine learning tasks demonstrate our proposed algorithms' efficiency. Our findings suggest further exploration of the existing tools from control theory in complex machine learning problems. The dissertation is concluded by showing that the potential in the previously mentioned idea of IPG goes beyond solving generic optimization problems through the development of a novel distributed beamforming algorithm and a novel observer for nonlinear dynamical systems, where IPG's robustness serves as a foundation in our designs. The proposed IPG for distributed beamforming (IPG-DB) facilitates a rapid establishment of communication links with far-field targets while jamming potential adversaries without assuming any feedback from the receivers, subject to unknown multipath fading in realistic environments. The proposed IPG observer utilizes a non-symmetric pre-conditioner, like IPG, as an approximation of the observability mapping's inverse Jacobian such that it asymptotically replicates the Newton observer with an additional advantage of enhanced robustness against measurement noise. Empirical results are presented, demonstrating both of these methods' efficiency compared to the existing methodologies

Softair: Software-defined networking and network function virtualization solutions for 5g cellular systems

One of the main building blocks and major challenges for 5G cellular systems is the design of flexible network architectures, which can be realized by the paradigm of software-defined networking (SDN) and network function virtualization (NFV). Existing commercial cellular systems rely on closed and inflexible hardware-based architectures both at the radio frontend and in the core network. These problems significantly delay the adoption and deployment of new standards, impose great challenges in implementing new techniques to maximize the network capacity and coverage, and prevent provisioning of truly-differentiated services for highly variable traffic patterns. The objective of this thesis is to introduce an innovative software-defined architecture for 5G cellular systems, called SoftAir. First, a detailed overview is provided for priori wireless SDN architecture solutions. Second, the SoftAir architecture is introduced with key design elements. Third, four essential management tools for SoftAir are developed. Last, novel software-defined traffic engineering, enabled by SoftAir, are proposed. Through the synergy of SDN and NFV, SoftAir enables the next-generation cellular networks with the needed flexibility for evolving and adapting to the ever-changing network context, and lays out the foundation for 5G wireless software-defined cellular systems.Ph.D.Ph.D

Air Force Institute of Technology Research Report 1997

This report summarizes the research activities of the Air Force Institute of Technology\u27s Graduate School of Engineering and the Graduate School of Logistics and Acquisition Management. It describes research interests and faculty expertise; list student theses/dissertations; identifies research sponsors and contributions; and outlines the procedure for contacting either school

New Waves of IoT Technologies Research – Transcending Intelligence and Senses at the Edge to Create Multi Experience Environments

The next wave of Internet of Things (IoT) and Industrial Internet of Things (IIoT) brings new technological developments that incorporate radical advances in Artificial Intelligence (AI), edge computing processing, new sensing capabilities, more security protection and autonomous functions accelerating progress towards the ability for IoT systems to self-develop, self-maintain and self-optimise. The emergence of hyper autonomous IoT applications with enhanced sensing, distributed intelligence, edge processing and connectivity, combined with human augmentation, has the potential to power the transformation and optimisation of industrial sectors and to change the innovation landscape. This chapter is reviewing the most recent advances in the next wave of the IoT by looking not only at the technology enabling the IoT but also at the platforms and smart data aspects that will bring intelligence, sustainability, dependability, autonomy, and will support human-centric solutions.acceptedVersio

Proceedings of the Third International Mobile Satellite Conference (IMSC 1993)

Satellite-based mobile communications systems provide voice and data communications to users over a vast geographic area. The users may communicate via mobile or hand-held terminals, which may also provide access to terrestrial cellular communications services. While the first and second International Mobile Satellite Conferences (IMSC) mostly concentrated on technical advances, this Third IMSC also focuses on the increasing worldwide commercial activities in Mobile Satellite Services. Because of the large service areas provided by such systems, it is important to consider political and regulatory issues in addition to technical and user requirements issues. Topics covered include: the direct broadcast of audio programming from satellites; spacecraft technology; regulatory and policy considerations; advanced system concepts and analysis; propagation; and user requirements and applications

Aeronautical engineering: A continuing bibliography with indexes (supplement 295)

This bibliography lists 581 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System in Sep. 1993. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

SIMULATING SEISMIC WAVE PROPAGATION IN TWO-DIMENSIONAL MEDIA USING DISCONTINUOUS SPECTRAL ELEMENT METHODS

We introduce a discontinuous spectral element method for simulating seismic wave in 2- dimensional elastic media. The methods combine the flexibility of a discontinuous finite element method with the accuracy of a spectral method. The elastodynamic equations are discretized using high-degree of Lagrange interpolants and integration over an element is accomplished based upon the Gauss-Lobatto-Legendre integration rule. This combination of discretization and integration results in a diagonal mass matrix and the use of discontinuous finite element method makes the calculation can be done locally in each element. Thus, the algorithm is simplified drastically. We validated the results of one-dimensional problem by comparing them with finite-difference time-domain method and exact solution. The comparisons show excellent agreement

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

The Domestication of Voice Activated -Technology & EavesMining: Surveillance, Privacy and Gender Relations at Home

This thesis develops a case study analysis of the Amazon Echo, the first-ever voice-activated smart speaker. The domestication of the devices feminine conversational agent, Alexa, and the integration of its microphone and digital sensor technology in home environments represents a moment of radical change in the domestic sphere. This development is interpreted according to two primary force relations: historical gender patterns of domestic servitude and eavesmining (eavesdropping + datamining) processes of knowledge extraction and analysis. The thesis is framed around three pillars of study that together demonstrate: how routinization with voice-activated technology affects acoustic space and ones experiences of home; how online warm experts initiate a dialogue about the domestication of technology that disregards and ignores Amazons corporate privacy framework; and finally, how the technologys conditions of use silently result in the deployment of ever-intensifying surveillance mechanisms in home environments. Eavesmining processes are beginning to construct a new world of media and surveillance where every spoken word can potentially be heard and recorded, and speaking is inseparable from identification

Reports to the President

A compilation of annual reports for the 1988-1989 academic year, including a report from the President of the Massachusetts Institute of Technology, as well as reports from the academic and administrative units of the Institute. The reports outline the year's goals, accomplishments, honors and awards, and future plans