Exploring a Tradition Identity: Gwangdaejeon in Jeonju, an Innovative Strategy in Pansori Popularization.

M.A. Thesis. University of Hawaiʻi at Mānoa 2017

Molecular Mechanisms Underlying Stress-Induced GLIA Remodeling in the Nematode C. Elegans

Animals can adapt to long-term environmental changes by modifying their behavior, which can be accompanied by structural alterations of the nervous system. Such alterations are common in sensory organs, composed of sensory neurons and glia, which initially detect environmental stress. The molecular mechanisms driving cell shape remodeling following environmental stress and the effects of such remodeling on animal survival are not well understood. C. elegans is an excellent model in which to study neuronal and glial cell remodeling. Under normal growth conditions, the sensory receptive endings of the bilateral AWC sensory neurons, which respond to volatile odorants, are individually ensheathed by processes of adjacent amphid sheath (AMsh) glial cells. Upon exposure to high temperature, starvation, or crowding, animals enter an alternative developmental state, called dauer, in which bilateral AMsh glia membranes surrounding the AWC neuron fuse, connecting the two glial cells, and allowing the AWC neuronal receptive endings to expand. Previous studies from our lab identified several AMsh glia proteins required for remodeling. These include (1) the cell fusion protein AFF-1, (2) a VEGFR-related protein VER-1, (3) the Otd/Otx transcription factor TTX-1, and (4) the zinc-finger transcription factor ZTF-16. ver-1 expression in AMsh glia is induced by dauer entry or by cultivation Ph.D. at high temperature, and requires direct binding of TTX-1 to ver-1 regulatory sequences. To identify additional genes involved in stress-induced sensory organ remodeling, we performed a forward genetic screen, seeking mutants in which ver-1 expression at high temperature is not induced. One mutant recovered from this screen harbors a causal lesion in F47D2.11 gene, which encodes a 7- transmembrane G-protein coupled receptor (GPCR). Mutations in F47D2.11 not only block ver-1 induction, but also prevent dauer-induced AMsh glia remodeling and result in a delay in exit from the dauer state following exposure to a favorable environment. F47D2.11 mutants can be rescued by expression of the wild-type cDNA in AMsh glia but not in AWC neurons. These results implicate F47D2.11 in the sensation of dauer conditions in AMsh glia, required for dauer-induced glial remodeling and timely dauer exit

Cooperative control of multi-uavs under communication constraints.

This research aims to develop an analysis and control methodology for the multiple un-manned aerial vehicles (UAVs), connected over a communication network. The wireless communication network between the UAVs is vulnerable to errors and time delays, which may lead to performance degradation or even instability. Analysis on the effects of the potential communication constraints in the multiple UAV control is a critical issue for successful operation of multiple UAVs. Therefore, this thesis proposes a systematic method by incorporating three steps: proposing the analysis method and metrics considering the wireless communication dynamics, designing the structure of the cooperative controller for UAVs, and applying the analysis method to the proposed control in representative applications. For simplicity and general insights on the effect of communication topology, a net-worked system is first analysed without considering the agent or communication dynamics. The network theory specifies important characteristics such as robustness, effectiveness, and synchronisability with respect to the network topology. This research not only reveals the trade-off relationship among the network properties, but also proposes a multi-objective optimisation (MOO) method to find the optimal network topology considering these trade-offs. Extending the analysis to the networked control system with agent and communication dynamics, the effect of the network topology with respect to system dynamics and time delays should be considered. To this end, the effect of communication dynamics is then analysed in the perspective of robustness and performance of the controller. The key philosophy behind this analysis is to approximate the networked control system as a transfer function, and to apply the concepts such as stability margin and sensitivity function in the control theory. Through the analysis, it is shown that the information sharing between the agents to determine their control input deteriorates the robustness of their stability against system uncertainties. In order to compensate the robustness and cancel out the effect of uncertainties, this thesis also develops two different adaptive control methods. The proposed adaptive control methods in this research aim to cope with unmatched uncertainty and time-varying parameter uncertainty, respectively. The effect of unmatched uncertainty is reduced on the nominal performance of the controller, using the parameter-robust linear quadratic Gaussian method and adaptive term. On the other hand, time-varying parameter uncertainty is estimated without requiring the persistent excitation using concurrent learning with the directional forgetting algorithm. The stability of the tracking and parameter estimation error is proved using Lyapunov analysis. The proposed analysis method and control design are demonstrated in two application examples of a formation control problem without any physical interconnection between the agents, and an interconnected slung-load transportation system. The performance of the proposed controllers and the effect of topology and delay on the system performance are evaluated either analytically or numerically.PhD in Aerospac

Stochastic Processes and the Dirac Equation with External Fields

The equation describing the stochastic motion of a classical particle in 1+1-dimensional space-time is connected to the Dirac equation with external gauge fields. The effects of assigning different turning probabilities to the forward and the backward moving particles in time are discussed.Comment: 9 pages, 1 figure, scalar parts eliminate

Concurrent learning adaptive control with directional forgetting

This paper proposes a new concurrent learning-based adaptive control algorithm. The main objective behind our proposition is to relax the persistent excitation requirement for the stability guarantee, while providing the ability to identify time-varying parameters. To achieve the objective, this paper designs a directional forgetting algorithm, which is then integrated with the adaptive law. The theoretical stability analysis shows that the tracking and parameter estimation error is exponentially stable with the signal only finitely excited, not persistently excited. The analysis also shows that the proposed algorithm can guarantee the stability under time-varying parameters. Moreover, the necessary and sufficient conditions for the stability given the time-varying parameters are derived. The results of numerical simulations confirm the validity of the theoretical analysis results and demonstrate the performance of the proposed algorithm

Approximation of achievable robustness limit based on sensitivity inversion

Introduction: The sensitivity function, defined as the closed-loop transfer function from the exogenous input to the tracking error, is central to the multi-objective design and analysis of a feedback control system. Its frequency response determines many performance characteristics of the closed-loop system, such as disturbance attenuation, reference tracking, and robustness against uncertainties and noise. It is well known that the nominal sensitivity peak, i.e., the H∞ -norm of the sensitivity function, is a direct measure of stability robustness, because the sensitivity magnitude quantifies both the attenuation of the effect of external disturbances on the closed-loop output and the variations of the closed-loop system with respect to the plant perturbations

Unmanned aerial system concept design for rail yard monitoring

Safety and security monitoring in large yard areas, typical in rail yard environments, is an important task and any trespassing or vandalizing incidents can cause significant disruptions to routine activities and possibly to staff safety. This can impact normal rail network operation. This paper investigates the feasibility of using low-cost unmanned aerial systems (UAS) for monitoring rail yards. A rigorous literature survey on unmanned aerial vehicles (UAV) platforms for monitoring in various sectors is conducted. Given the large area of the rail yard, a concept of multiple rotor-based UAVs is explored with a particular eye on energy-efficiency. The proposed concept is validated hardware-wise through multiple flights conducted to monitor a scale-down setup of a "yard" concept in the lab's indoor flying arena. Analysis of the results showcases the potential of using low-cost multirotor UAV solutions for monitoring assistance in large yards