Doctor of Philosophy, The Ohio State University, 2022, Electrical and Computer Engineering

The aircraft industry, commercial utilities, and federal agencies, such as NASA, are investing in aircraft solutions for a more sustainable, cleaner, and quieter transportation solutions for people and cargo. One option that is actively considered is that of a hybrid-electric aircraft, and in this application the energy storage system (ESS) may consist of thousands or even tens of thousands of cells. These cells are then connected in series and in parallel to form modules, which then are assembled into battery packs to meet energy and power requirements, resulting in systems that are large-dimensional and that have complex interconnections. Because of differences in cell electrical and thermal characteristics and in cell aging, the energy/power density and the durability and safety of the battery packs will be reduced to a certain extent compared with individual cells. It is therefore very important to design a battery management system (BMS) that can enable cell level monitoring and that is capable of diagnosing faults that are considered to be critical. This dissertation presents some design aspects for a battery pack intended for aviation application and its BMS considering safety, health and safety monitoring, and diagnostics. Generalized equivalent circuit models (GECMs) are used to predict the overall battery pack performance and to investigate the different behavior of different battery pack architectures in the case of cell-to-cell parameter variations or in the case of faults. A comparative analysis between different battery pack architectures is conducted as well, to determine a better architecture that is more reliable in the case of a cell fault. A set of critical faults is selected for fault modeling to augment the battery cell model and pack model. The battery pack model with fault modeling is then used in a Software-In-the-Loop (SIL) framework under the NASA ULI hybrid turbo-electric aircraft case scenario with the purpose of understanding the perform (open full item for complete abstract)

Committee: Giorgio Rizzoni Professor (Advisor); Qadeer Ahmed Professor (Committee Member); Jin Wang Professor (Committee Member) Subjects: Aerospace Engineering; Automotive Engineering; Computer Engineering; Electrical Engineering

PhD, University of Cincinnati, 2021, Engineering and Applied Science: Aerospace Engineering

In the coming years, the number of small Unmanned Aerial Systems (sUAS) operating in low-altitude, uncontrolled airspace is expected to vastly increase. These vehicles must be able to successfully navigate their assigned missions, while ensuring the safety of people and property below. Therefore, finding solutions to managing sUAS in highly congested airspace is vital. In this dissertation an intelligent system is used to help identify, track, and manage large-scale sUAS operations using a novel sUAS Traffic Management (UTM) system. Due to the size and weight of sUAS, these vehicles pose many unique challenges that are not addressed by existing solutions, including high maneuverability and onboard instrument/sensor limitations. To develop and test the various aspects of this work a realistic fast-time simulation (FTS) was created. This FTS can serve as a tool for future researchers to explore other policies and concepts surrounding UTM in a close-to-reality environment. To identify and track the sUAS throughout their missions a novel tracking system was developed, which fuses data from three different sensor platforms to estimate the state of each vehicle. The tracking system within was able to successfully identify all sUAS, perfectly associate all data points to the correct tracks, and provide an accurate position and velocity estimation at all time steps. The conflict detection and resolution (CD&R) system within provides multi-layered tactical conflict detection and resolution services. This system is referred to as the Tactical Intelligent Detect and Avoid System for Drones (TIDAS-4D). Each layer uses a unique set of high-level heuristics to determine the appropriate action to resolve the conflict and a low-level fuzzy logic system to perform the desired action. TIDAS-4D was evaluated for its effectiveness at mitigating the risk of losses of separation (LOSs), near mid-air collisions (NMACs), and collisions between aircraft. Using only current-state info (open full item for complete abstract)

Committee: Kelly Cohen Ph.D. (Committee Chair); Manish Kumar Ph.D. (Committee Member); George T. Black M.S. (Committee Member); Min Xue Ph.D. (Committee Member) Subjects: Aerospace Materials

Master of Science (MS), Wright State University, 2018, Computer Science

Asthma is a high-burden chronic inflammatory disease with prevalence in children with twice the rate compared to adults. It can be improved by continuously monitoring patients and their environment using the Internet of Things (IoT) based devices. These sensor data streams so obtained are essential to comprehend multiple factors triggering asthma symptoms. In order to support physicians in exploring causal associations and finding actionable insights, a visualization system with a scalable cloud infrastructure that can process multimodal sensor data and Patient Generated Health Data (PGHD) is necessary. In this thesis, we describe a cloud-based asthma management and visualization platform that integrates personalized PGHD from kHealth kit and outdoor environmental observations from web services. When applied to data from an individual, the tool assists in analyzing and explaining symptoms using "personalized" causes, monitor disease progression, and improve asthma management. The front-end visualization was built with Bootstrap Framework and Highcharts. Google's Firebase and Elasticsearch engine were used as back-end storage to aggregate data from various sources. Further, Node.js and Express Framework were used to develop several Representational State Transfer services useful for the visualization.

Committee: Amit Sheth Ph.D. (Advisor); Krishnaprasad Thirunarayanan Ph.D. (Committee Member); Maninder Kalra Ph.D. (Committee Member); Valerie Shalin Ph.D. (Committee Member) Subjects: Computer Science; Health

Master of Science, University of Akron, 2015, Computer Engineering

A novel approach to recognizing and correcting errors in exercise activity based on skeletal joint data obtained from the Kinect 2.0 sensor is presented. Many approaches in the literature for analyzing human motion focus on training a classifier to recognize and/or rank the motions. While effective in some situations, the computational costs of training the models, the unavailability of reference motions and the inability to provide real-time guidance and feedback limit the utility of such approaches for empowering wellness management. A classification technique is used to recognize exercises and a geometric characterization of poses is used to detect errors in the recognized exercises. All the features used are extracted from the time-series data collected from a Microsoft Kinect 2.0 camera. Expert domain knowledge was easily integrated to identify errors in exercise performance. The simplicity and the low computational costs, make this approach useful for providing real-time feedback and guidance to participants, thus improving exercise adherence. Experimental results that demonstrate the viability of the approach are presented. In the future, this approach can be extended to a wider range of exercises and similar techniques can be applied to address related problems in rehabilitation, surveillance and remote user interaction.

Committee: Shivakumar Sastry Dr. (Advisor); Forrest Bao Dr. (Committee Member); Jin Kocsis Dr. (Committee Member); Victor Pinheiro Dr. (Committee Member) Subjects: Computer Engineering

Doctor of Philosophy, Case Western Reserve University, 2014, EECS - Electrical Engineering

This work describes the design and testing of a wireless implantable bladder pressure sensor suitable for chronic implantation in humans. The sensor was designed to fulfill the unmet need for a chronic bladder pressure sensing device in urological fields such as urodynamics for diagnosis and neuromodulation for bladder control. Neuromodulation would particularly benefit from a wireless bladder pressure sensor providing real-time pressure feedback to an implanted stimulator, resulting in greater bladder capacity while using less power. The pressure sensing system consists of an implantable microsystem, an external RF receiver, and a wireless battery charger. The implant is small enough to be cystoscopically implanted within the bladder wall, where it is securely held and shielded from the urine stream, protecting both the device and the patient. The implantable microsystem consists of a custom application-specific integrated circuit (ASIC), pressure transducer, rechargeable battery, and wireless telemetry and recharging antennas. Because the battery capacity is extremely limited, the ASIC was designed using an ultra-low-power methodology in which power is dynamically allocated to instrumentation and telemetry circuits by a power management unit. A low-power regulator and clock oscillator set the minimum current draw at 7.5 µA and instrumentation circuitry is operated at low duty cycles to transmit 100-Hz pressure samples while consuming 74 µA. An adaptive transmission activity detector determines the minimum telemetry rate to limit broadcast of unimportant samples. Measured results indicated that the power management circuits produced an average system current of 16 µA while reducing the number of transmitted samples by more than 95% with typical bladder pressure signals. The wireless telemetry range of the system was measured to be 35 cm with a bit-error-rate of 10-3, and the battery was wirelessly recharged at distances up to 20 cm. A novel biocompatible (open full item for complete abstract)

Committee: Steven Garverick (Advisor); Swarup Bhunia (Committee Co-Chair); Margot Damaser (Committee Member); Pedram Mohseni (Committee Member); Christian Zorman (Committee Member) Subjects: Biomedical Engineering; Electrical Engineering

Master of Science in Engineering, Youngstown State University, 2010, Department of Electrical and Computer Engineering

A wireless sensor mesh network for health monitoring of structures is presented. It is a low cost, easy to deploy, fast and reliable wireless sensor network. Wireless nodes are all identical to each other with on board sensors for measuring acceleration and temperature. The acceleration data from the nodes used to detect the strain of the structure was calibrated using a Vishay P3 strain gauge instrument. These sensor nodes can collect data as well as relay the data of the neighboring nodes. Data from all the nodes reaches the base station through multiple hop relays. The nodes were tested for their performance by using different frequency channels and radio output power levels. This network implements an energy efficient routing protocol which can also handle a node failure in route without losing data. Different power conservation techniques were discussed which can keep the network unattended for a week after being deployed on the structure.

Committee: Frank Li PhD (Advisor); Philip Munro PhD (Committee Member); Faramarz Mossayebi PhD (Committee Member) Subjects: Civil Engineering; Computer Science; Electrical Engineering; Engineering

PhD, University of Cincinnati, 2008, Engineering : Computer Science and Engineering

Wireless Ad Hoc Networks have emerged as an advanced networking paradigm based on collaborative efforts among multiple self-organized wireless communication devices. Without the requirement of a fixed infrastructure support, wireless ad hoc networks can be quickly deployed anywhere at any time when needed. The decentralized nature, minimal configuration and quick deployment of wireless ad hoc networks make them suitable for various applications, from disaster rescue, target tracking to military conflicts. Wireless ad hoc networks can be further categorized into mobile ad hoc networks (MANETs), wireless sensor networks (WSNs), and wireless mesh networks (WMNs) depending on their applications.Security is a big challenge in wireless ad hoc networks due to the lack of any infrastructure support, dynamic network topology, shared radio medium, and resource-constrained wireless users. Most existing security mechanisms applied for the Internet or traditional wireless networks are neither applicable nor suitable for wireless ad hoc network environments. In MANETs, routing security is an extremely important issue, as the majority of the standard routing protocols assume non-hostile environments. Once deployed in a hostile environment and working in an unattended mode, existing routing protocols are vulnerable to various attacks. To address these concerns, we propose an anonymous secure routing protocol for MANETs in this dissertation, which can be incorporated with existing routing protocols and achieve enhanced routing security with minimum additional overheads. In WSNs, key distribution and management is the core issue of any security approaches. Due to extremely resource-constrained sensor nodes and lack of any infrastructure support, traditional public-key based key distribution and management mechanisms are commonly considered as too expensive to be employed in WSNs. In this dissertation, we propose two efficient pairwise key pre-distribution and management mechanisms f (open full item for complete abstract)

Committee: Dharma Agrawal (Committee Chair); Jerome Paul (Committee Member); Wen-Ben Jone (Committee Member); Chia-Yung Han (Committee Member); Ernest Hall (Committee Member) Subjects: Communication; Computer Science

PhD, University of Cincinnati, 2006, Engineering : Computer Science and Engineering

As the earliest standard for Wireless Personal Area Networks (WPAN), Bluetooth has been widely used in cell phone, headset, car, GPS, etc. As a frequency hopping based system, however, constructing a large scale network using Bluetooth technology presents a real challenge. This dissertation explores this problem and presents several feasible solutions. Firstly, bridge devices, which connect multiple piconets into a connected scatternet by participating in a time division multiplex basis in adjacent piconets, need to be carefully coordinated to enable smooth operations of the scatternet; secondly, the lengthy device discovery and link setup phases make scatternets impossible to maintain, without disruptive interruptions to normal data communications. To address the bridge coordination problem efficiently and effectively, this dissertation proposes a novel distributed dichotomized bridge scheduling algorithm, coupled with an adaptive Rendezvous Window based polling scheme. A new method for device discovery is also introduced to address the scatternet formation and maintenance problems. The proposed algorithms have been tested on our own Bluetooth simulator (UCBT) which models the lower part of Bluetooth stack in detail and provides several example large scale scatternet configurations for executing our proposed scheduling algorithms. Extensive simulations have been conducted, and the performance results illustrate that large scale scatternets can operate efficiently. This dissertation also looks at applying scatternets to sensor networks by constructing a 480 nodes scatternet in our simulator. The simulation results illustrate that Bluetooth scatternet can be a good choice for low duty cycle sensor networks. The scheduling technique developed in Bluetooth scatternet can be applied to newly introduced IEEE 802.15.4 based Zigbee network as well. This is a new standard introduced to save consumed energy by defining a beacon controlled low duty cycle. Beacon collision pro (open full item for complete abstract)

Committee: Dr. Dharma Agrawal (Advisor) Subjects: Computer Science

Doctor of Philosophy, The Ohio State University, 2010, Electrical and Computer Engineering

Recent advances in wireless networking and data acquisition have enabled us with a unique capability to remotely sense our environment. Data acquisition networks can be used to sense natural as well as human-created phenomena. As these applications may require deployment in remote and hard-to-reach areas, it is critical to ensure that such wireless sensor networks are capable of operating unattended for long durations. The lack of easy access to a continuous power source in most scenarios and the limited lifetime of batteries have hindered the deployment of such networks. Consequently, the central objective in wireless sensor network design is to utilize the available energy as efficiently as possible. In this thesis, we study the design of optimal or near-optimal energy management schemes for various wireless sensor networks composed of nodes with different capabilities. Firstly, we derive theoretical upper bounds on the performance of a transmission scheduler for sensor networks. We do this by calculating the information theoretic channel capacity of finite-state Markov channels with imperfect feedback containing different grades of channel state information including that, obtained through Automatic Repeat Request (ARQ) feedback. Secondly, we consider the problem of energy optimal transmission scheduling over a finite state Markov channel with imperfect feedback. We propose a transmission controller that utilizes different "grades" of channel state information to schedule packet transmissions in an energy-optimal way, while meeting a deadline constraint for all packets waiting in the transmission queue. Our scheduler is readily implementable and it is based on the dynamic programming solution to the finite-horizon transmission control problem. We illustrate that our scheduler achieves a given throughput at a power level that is fairly close to the information-theoretic limit. Finally, we consider the problem of energy management in nodes with energy replenishment (open full item for complete abstract)

Committee: Can Emre Koksal PhD (Committee Chair); Ness B. Shroff PhD (Committee Member); Eylem Ekici PhD (Committee Member) Subjects: Electrical Engineering

Doctor of Philosophy, The Ohio State University, 2006, Computer and Information Science

Wireless sensor networks have shown great potential as the technology that will change the way we interact with the physical world around us and have forced researchers to reconsider the way they think about distributed systems. However, these networks have to deal with a great deal of uncertainty arising out of the unique differences in their computational model such as unreliable communication, severely resource constrained devices and vulnerability to different types of faults. To meet these challenges, we must first understand the different reliability issues related to wireless sensor networks and then design appropriate mechanisms to deal with them. We believe network management to be a key enabler for such networks to deal with these challenges. In this dissertation, we first present a comprehensive study of different types of node and network faults that occur in wireless sensor networks and propose a fault model for these networks. Based on this fault model, we identify key elements of a network management architecture for wireless sensor networks. We then present MASE, a Management Architecture for SEnsor networks, that addresses management issues at all levels in a sensor network: at individual nodes, in the network, and also at the base station. We emphasize self-stabilizing designs for MASE components to deal with anticipated and unanticipated faults. We present key network management services such as the Stabilizing Reconfiguration service, the Chowkidar health monitoring service and the Reporter termination detection service that we have designed and implemented as part of MASE. We also present our network-based experiment orchestration framework which closes the loop in sensor network management by automating common execution and experimentation patterns. The different architectural components presented in this dissertation have been validated not only through experiments, but also in field deployments for managing large scale sensor network systems (open full item for complete abstract)

Committee: Anish Arora (Advisor) Subjects: Computer Science

Doctor of Philosophy, The Ohio State University, 2005, Electrical Engineering

Sensor management (SM) is one of the key factors that determine the performance of a multi-sensor system, especially when the system consists of mobile sensor agents (MSA). Due to the strong interconnection between information processing and MSA motion control, a new set of theoretical foundations, design principles and performance metrics are needed. This dissertation presents a few attempts toward this goal by jointly studying the target-track-maintenance problem and the MSA motion-planning problem through the MSA-target scenario. First, a generic method for target track maintenance, the BF-HMap approach, is proposed based on the Bayesian filtering method and the hospitability map . An advanced version of this approach with much less computational and memory load using a particle filter, the PF-HMap algorithm, is also introduced in this work. Both BF-HMap and PF-HMap are capable of exploiting non-analytic prior environmental knowledge as well as handling intermittent and regional measurements caused by the coverage and motion constraints on MSAs. Meanwhile, a generalized particle filter for both in-sequence and out-of-sequence measurements is developed for possible extensions of the PF-HMap algorithm to distributed MSA networks. Secondly, the MSA motion-control problem is studied in such an information-theoretic way that the conditional entropy (i.e. given the measurements) of the target state is chosen as a generic performance metric. Several key properties of the evolution of the entropy are identified, which are further exploited to model the sensor management problem in two cases of studies: target search and target surveillance, which are modeled as a stabilization problem of the entropy and an optimization problem to minimize the average revisit time on each target, respectively. Based on that, a necessary condition and a sufficient condition by means of the number of MSAs to perform a non-escape search for a moving target are derived. In the meantime, a co (open full item for complete abstract)

Committee: Umit Ozguner (Advisor) Subjects:

Doctor of Philosophy, Case Western Reserve University, 2008, Computer Engineering

The Internet represents a shared resource, wherein users contend for the finite network bandwidth. Contention among independent user demands can result in congestion, which, in turn, leads to long queueing delays, packet losses or both. Congestion control regulates the rate at which traffic sources inject packets into a network to ensure high bandwidth utilization while avoiding network congestion. In this thesis, we present contributions pertaining to two specific areas in the Internet congestion control: PI AQM and bandwidth allocation in Cyber-Physical Systems (CPSs). In the area of PI AQM, we present an analytic derivation of the complete stability region. The stability region represents the entire set of the feasible design parameters that stabilize the closed-loop TCP-AQM system. Utilizing the complete stability region, we show that the PI parameters used in the literature can be excessively conservative. We also show that provably stable controller parameters can exhibit widely different levels of performance. Furthermore, we present examples of PI controllers that are stable and have significantly better performance than previously proposed ones. These facts explain the previous observation about PI sluggish responsiveness and stress the importance of obtaining the complete stability region for the PI AQM. As for CPSs bandwidth allocation, we devise a bandwidth allocation scheme for Cyber-Physical Systems that have their control loops closed over a distributed network. We formulate the bandwidth allocation as a convex optimization problem. We then present an allocation scheme that solves this optimization problem in a fully distributed manner. In addition to being fully distributed, the proposed scheme is asynchronous, scalable, dynamic and flexible. Furthermore, we design robust and resilient queue controllers to enhance the performance of the bandwidth allocation scheme to better fulfill the requirements of the CPSs control loops. Throughout the thesis, we (open full item for complete abstract)

Committee: Vincenzo Liberatore (Advisor) Subjects: Computer Science

PhD, University of Cincinnati, 2013, Engineering and Applied Science: Computer Science and Engineering

Wireless sensor networks (WSNs) are one type of ad hoc networks with data-collecting function. Because of the low-power, low-cost features, WSN attracts much attention from both academia and industry. However, since WSN is driven by batteries and the multi-hop transmission pattern introduces energy hole problem, energy management of WSN became one of fundamental issues. In this dissertation, we study the energy management strategies for WSNs. Firstly, we propose a packets propagation scheme for both deterministic and random deployment of WSNs so to prolong their lifetime. The essence of packets propagation scheme is to control transmission power so as to balance the energy consumption for the entire WSN. Secondly, a characteristic correlation based data aggregation approach is presented. Redundant information during data collection can be effectively mitigated so as to reduce the packets transmission in the WSN. Lifetime of WSN is increased with limited overhead. Thirdly, we also provide a two-tier lifetime optimization strategy for wireless visual sensor network (VSN). By deploying redundant cheaper relay nodes into existing VSN, the lifetime of VSN is maximized with minimal cost. Fourthly, our two-tier visual sensor network deployment is further extended considering multiple base stations and image compression technique. Last but not the least, description of UC AirNet WSN project is presented. At the end, we also consider future research topics on energy management schemes for WSN.

Committee: Dharma Agrawal D.Sc. (Committee Chair); Kenneth Berman Ph.D. (Committee Member); Yizong Cheng Ph.D. (Committee Member); Chia Han Ph.D. (Committee Member); Wen Ben Jone Ph.D. (Committee Member) Subjects: Computer Engineering