Performance-Robust Dynamic Feedback Control of Lipschitz Nonlinear Systems

This dissertation addresses the dynamic control of nonlinear systems with finite energy noise in the state and measurement equations. Regional eigenvalue assignment (REA) is used to ensure that the state estimate error is driven to zero significantly faster than the state itself. Moreover, the controller is designed for the resulting closed loop system to achieve any one of a set of general performance criteria (GPC). The nonlinear model is assumed to have a Lipschitz nonlinearity both in the state and measurement equations. By using the norm bound of the nonlinearity, the controller is designed to be robust against all nonlinearities satisfying the norm-bound. A Luenberger-type nonlinear observer is used to estimate the system state, which is not directly measurable. The choice of the eigenvalue locations for the linear part of the system is based on the transient response specifications and the separation of the controller dynamics from the observer dynamics. Furthermore, the GPC are incorporated to achieve performance requirements such as H2, H∞, etc. The advantage of using GPC is it allows the designer flexibility in choosing a performance objective to tune the system. The design problem introduced in this dissertation uses various mathematical techniques to derive LMI conditions for the controller and observer design using REA, GPC, and the bounds on the Lipschitz nonlinearities. All work will be demonstrated in both continuous- and discrete-time. Illustrative examples in both time domains are given to demonstrate the proposed design procedure. Multiple numerical approaches are also presented and compared in simulations for ease of use, applicability, and conservatism

Observer Incorporated Neoclassical Controller Design: A Discrete Perspective

Control theory has generally been divided into two categories, modern control and classical control. Modern control uses state feedback to alter the pole locations of a given system. Classical control uses pre-compensation to alter the zeroes of the system and uses output feedback to adjust the poles to bring stability to the system. The drawback is that the application of classical control techniques can be a lengthy, complicated and iterative design process and in the end, classical control techniques still do not give information about the state of the system. Neoclassical control combines classical control techniques with the state feedback approach of modern control to stabilize the system, eliminate the steady state error, provide relevant internal state information, and reduce the time it takes to design the controller. This thesis explores the application of neoclassical control to discrete-time systems. The mass-spring-damper, magnetic levitation, and ball and beam systems are discretized using the zero-order-hold or the Euler approximation. State-feedback control is used to modify the pole locations for these systems. A discrete-time integrator is put in series to eliminate the steady-state error for a step input. The pre-compensator is also put in series to replace the numerator of the open-loop system with a desired numerator. The unit output-feedback is then used to close the loop. The closed-loop system will have a step response which matches the discrete-time optimal ITAE, Bessel, or Butterworth transfer functions. An observer is added to estimate the state of the plant in this work. The observer is applied to the discrete-time mass-spring-damper, the magnetic levitation, and the ball and beam systems in such a way that the error in the state estimate will be driven to zero within the desired period of time. This will allow the application of this controller to systems when the state is not known or measurable

Doctoral Recital

List of performers and performances

Assessing Neuronal and Astrocyte Derived Exosomes From Individuals With Mild Traumatic Brain Injury for Markers of Neurodegeneration and Cytotoxic Activity.

Mild traumatic brain injury (mTBI) disproportionately affects military service members and is very difficult to diagnose. To-date, there is currently no blood-based, diagnostic biomarker for mTBI cases with persistent post concussive symptoms. To examine the potential of neuronally-derived (NDE) and astrocytic-derived (ADE) exosome cargo proteins as biomarkers of chronic mTBI in younger adults, we examined plasma exosomes from a prospective longitudinal study of combat-related risk and resilience, marine resiliency study II (MRSII). After return from a combat-deployment participants were interviewed to assess TBI exposure while on deployment. Plasma exosomes from military service members with mTBI (mean age, 21.7 years, n = 19, avg. days since injury 151), and age-matched, controls (deployed service members who did not endorse a deployment-related TBI or a pre-deployment history of TBI; mean age, 21.95 years, n = 20) were precipitated and enriched against a neuronal adhesion protein, L1-CAM, and an astrocyte marker, glutamine aspartate transporter (GLAST) using magnetic beads to immunocapture the proteins and subsequently selected by fluorescent activated cell sorting (FACS). Extracted protein cargo from NDE and ADE preparations were quantified for protein levels implicated in TBI neuropathology by standard ELISAs and on the ultra-sensitive single molecule assay (Simoa) platform. Plasma NDE and ADE levels of Aβ42 were significantly higher while plasma NDE and ADE levels of the postsynaptic protein, neurogranin (NRGN) were significantly lower in participants endorsing mTBI exposure compared to controls with no TBI history. Plasma NDE and ADE levels of Aβ40, total tau, and neurofilament light (NFL), P-T181-tau, P-S396-tau were either undetectable or not significantly different between the two groups. In an effort to understand the pathogenetic potential of NDE and ADE cargo proteins, neuron-like cultures were treated with NDE and ADE preparations from TBI and non-TBI groups. Lastly, we determined that plasma NDE but not ADE cargo proteins from mTBI samples were found to be toxic to neuron-like recipient cells in vitro. These data support the presence of markers of neurodegeneration in NDEs of mTBI and suggest that these NDEs can be used as tools to identify pathogenic mechanisms of TBI

"I have failed to separate my HIV from this pain": the challenge of managing chronic pain among people with HIV

Pain is a highly prevalent and burdensome symptom among people with HIV (PWH). This study aims to identify how the experience of living with HIV and chronic pain influences pain beliefs, health-seeking and pain management. Thirty-nine purposively sampled PWH with chronic pain (sample characteristics = 61% women, 79% Black, Asian and minority ethnic groups, 18% men who have sex with men, 45-54 median age category) participated in focus groups in London. Focus groups were co-facilitated with community members. Transcripts wereanalysed using a thematic approach. Findings revealed that HIV stigma, fractured care pathways, and general practitioners' lack of HIV training are barriers to supported pain management. Unaddressed pain results in poorer mental health and reduced quality of life, which has important clinical implications for HIV treatment adherence. Creating HIV-specific pain resources, activating social networks, and pain self-management techniques are potential solutions. Person-centred assessment and HIV training is needed to help clinicians identify PWH with chronic pain. Clear guidelines need to be developed to identify which health service providers are responsible for chronic pain management in PWH. This study generated a refined version of the Fear Avoidance Model that introduces a dimension of HIV-specific behaviours that impact PWHs seeking chronic pain management

Inclusive Masculinity and Facebook Photographs Among Early Emerging Adults at a British University

Central to debates about the construction of masculinity in sociology is the influence of culture and what constitutes acceptable displays of masculinity. This article adopts a novel approach in examining this question. It adopts a summative content analysis, combined with a semiotic analysis, of 1,100 Facebook photographs, in order to explore the underlying meanings within the photos and the performances of masculinity. Facebook photographs from 44, straight, White, male, early emerging adults attending the same university are used as a representation of an individual’s ideal self. These are then analyzed in order to determine the behaviors endorsed by peer culture. It was found that the sample overwhelmingly adopted inclusive behaviors (including homosocial tactility, dancing, and kissing each other), and inclusive masculinity theory was utilized to contextualize participants’ constructions of masculinity. Thus, this research shows that emerging adult males at this university construct their masculine identities away from previous orthodox archetypes. It is argued that the reducing importance of gendered behavior patterns may represent an adoption of what are perceived as wider cultural norms and act as a symbol of adulthood to these early emerging adults

Quasi-Two-Body Decays of Nonstrange Baryons

We examine the decays of nonstrange baryons to the final states $\Delta\pi$, $N\rho$, $N\eta$, $N\eta^\prime$, $N\omega$, $N1/2^+(1440)\pi$, and $\Delta3/2^+(1600)\pi$, in a relativized pair-creation($^3P_0$) model which has been developed in a previous study of the $N\pi$ decays of the same baryon states. As it is our goal to provide a guide for the possible discovery of new baryon states at CEBAF and elsewhere, we examine the decays of resonances which have already been seen in the partial-wave analyses, along with those of states which are predicted by the quark model but which remain undiscovered. The level of agreement between our calculation and the available widths from the partial-wave analyses is encouraging.Comment: 41 pages, CEBAF-TH-93-1

The analysis of facial beauty: an emerging area of research in pattern analysis

Much research presented recently supports the idea that the human perception of attractiveness is data-driven and largely irrespective of the perceiver. This suggests using pattern analysis techniques for beauty analysis. Several scientific papers on this subject are appearing in image processing, computer vision and pattern analysis contexts, or use techniques of these areas. In this paper, we will survey the recent studies on automatic analysis of facial beauty, and discuss research lines and practical application

Scheduling with Sequencing Flexibility *

This study examines the effects of sequencing flexibility on the performance of rules used to schedule operations in manufacturing systems. The findings show that taking advantage of even low levels of sequencing flexibility in the set of operations required to do a job results in substantial improvement in the performance of scheduling rules with respect to mean flowtime. Differences in the mean flowtime measure for various rules also diminish significantly with increasing sequencing flexibility. Performance improvements additionally result for such due-date related performance measures as mean tardiness and the proportion of jobs tardy. At high levels of sequencing flexibility, some nonparametric scheduling rules outperform the shortest processing time rule in terms of the mean flowtime criterion. Rules based on job due dates also outperform rules based on operation milestones in terms of tardiness related criteria at high levels of sequencing flexibility. The implications of these findings for the design of manufacturing systems and product design are noted.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73893/1/j.1540-5915.1993.tb00477.x.pd