Proceedings, MSVSCC 2017

Proceedings of the 11th Annual Modeling, Simulation & Visualization Student Capstone Conference held on April 20, 2017 at VMASC in Suffolk, Virginia. 211 pp

Diagnosis and Management of Heart Failure

Heart failure prevalence continues to rise globally. Regardless of the underlying etiology, heart failure remains a progressive disease, largely irreversible and end-stage heart failure requires transplantation. Book focuses on the challenges and recent advances of diagnosis, treatment and prevention of heart failure with or without associated comorbidities. We hope that readers will appreciate the wide breadth of topics and clinical utility of the articles and reviews included to this book collection

A novel dual-spin actuation mechanism for small calibre, spin stabilised, guided projectiles

© Cranfield University 2022. All rights reserved. No part of this publication may be reproduced without the written permission of the author and copyright holderSmall calibre projectiles are spin-stabilised to increase ballistic stability, often at high frequencies. Due to hardware limitations, conventional actuators and meth ods are unable to provide satisfactory control at such high frequencies. With the reduced volume for control hardware and increased financial cost, incorporating traditional guid ance methods into small-calibre projectiles is inherently difficult. This work presents a novel method of projectile control which addresses these issues and conducts a systems level analysis of the underlying actuation mechanism. The design is shown to be a viable alternative to traditional control methods, Firstly, a 7 Degree-of-Freedom (DoF) dynamic model is created for dual-spin pro jectiles, including aerodynamic coefficients. The stability of dual-spin projectiles, gov erned by the gyroscopic and dynamic stability factors is given, discussed and unified across available literature. The model is implemented in a Matlab/Simulink simulation environ ment, which is in turn validated against a range of academic literature and experimental test data. The novel design and fundamental operating principle are presented. The actuation mechanism (AM) is then mathematically formulated from both a velocity change (∆V ) and a lateral acceleration (a˜) perspective. A set of axioms are declared and verified using the 7-DoF model, showing that the inherently discrete system behaviour can be controlled continuously via these control variables, ∆V or a˜. Control state switching is simplified to be instantaneous, then expanded to be generically characterised by an arbitrarily complex mathematical function. A detailed investigation, parametric analysis and sensitivity study is undertaken to understand the system behaviour. A Monte Carlo procedure is described, which is used to compare the correction cap abilities of different guidance laws (GLs). A bespoke Zero-Effort-Miss (ZEM) based GLis synthesised from the mathematical formulation of the AM, with innately more know ledge of the system behaviour, which allows superior error correction. This bespoke GL is discussed in detail, a parametric study is undertaken, and both the GL parameters and PID controller gains are optimised using a genetic algorithm. Artificial Intelligence (AI) Reinforcement learning methods are used to emulate a GL, as well as controlling the AM and operating as a GL, simultaneously. The novel GLs are compared against a traditional proportional navigation GL in a nominal system and all GLs were able to control the AMs, reducing the miss distance to a satisfactory margin. The ZEM-based GL provided superior correction to the AI GL, which in turn provided superior correction over proportional navigation. Example CAD models are shown, and the stability analysis is conducted on the geometry. The CAD model is then used in CFD simulations to determine aerodynamic coefficients for use in the 7-DoF dynamic model. The novel control method was able to reduce the 95% dispersion diameter of a traditional ballistic 7.62mm projectile from 70mm to 33mm. Statistical data analysis showed there was no significant correlation or bias present in either the nominal or 7-DoF dispersion patterns. This project is co-sponsored by BAE Systems and ESPRC (ref. 1700064). The con tents of this thesis are covered by patent applications GB2011850.1, GB 2106035.5 and EP 20275128.5. Two papers are currently published (DOI: 10.1016/j.dt.2019.06.003, the second DOI is pending) and one is undergoing peer review..PH

Development and analysis of a small satellite attitude determination and control system testbed

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 263-267).Attitude Determination and Control Systems (ADCS) are critical to the operation of satellites that require attitude knowledge and/or attitude control to achieve mission success. Furthermore, ADCS systems only operate as designed in the reduced friction, micro-gravity environment of space. Simulating these characteristics of space in a laboratory environment in order to test individual ADCS components and integrated ADCS systems is an important but challenging step in verifying and validating a satellite's ADCS design. The purpose of this thesis is to design and develop an ADCS testbed capable of simulating the reduced fiction, micro-gravity environment of space within the Massachusetts Institute of Technology's Space Systems Laboratory. The ADCS testbed is based on a tabletop style, three degree of freedom, rotational air bearing, which uses four reaction wheels for attitude control and a series of sensors for attitude determination. The testbed includes all the equipment necessary to allow for closed loop testing of individual ADCS components and integrated ADCS systems in the simulated inertial environment of space. In addition to the physical ADCS testbed, a MATLAB Simulink based model of the ADCS testbed is developed to predict the performance of hardware components and software algorithms before the components and algorithms are integrated into the ADCS testbed. The final objective of this thesis is to validate the operation of the ADCS testbed and simulation to prepare the tool for use by satellite design teams.by Corey Whitcomb Crowell.S.M

Oracle-Guided Design and Analysis of Learning-Based Cyber-Physical Systems

We are in world where autonomous systems, such as self-driving cars, surgical robots, robotic manipulators are becoming a reality. Such systems are considered \textit{safety-critical} since they interact with humans on a regular basis. Hence, before such systems can be integrated into our day to day life, we need to guarantee their safety. Recent success in machine learning (ML) and artificial intelligence (AI) has led to an increase in their use in real world robotic systems. For example, complex perception modules in self-driving cars and deep reinforcement learning controllers in robotic manipulators. Although powerful, they introduce an additional level of complexity when it comes to the formal analysis of autonomous systems. In this thesis, such systems are designated as Learning-Based Cyber-Physical Systems~(LB-CPS). In this thesis, we take inspiration from the Oracle-Guided Inductive Synthesis~(OGIS) paradigm to develop frameworks which can aid in achieving formal guarantees in different stages of an autonomous system design and analysis pipeline. Furthermore, we show that to guarantee the safety of LB-CPS, the design (synthesis) and analysis (verification) must consider feedback from the other. We consider five important parts of the design and analysis process and show a strong coupling among them, namely (i) Robust Control Synthesis from High Level Safety Specifications; (ii) Diagnosis and Repair of Safety Requirements for Control Synthesis; (iii) Counter-example Guided Data Augmentation for training high-accuracy ML models; (iv) Simulation-Guided Falsification and Verification against Adversarial Environments; and (v) Bridging Model and Real-World Gap. Finally, we introduce a software toolkit \verifai{} for the design and analysis of AI based systems, which was developed to provide a common formal platform to implement design and analysis frameworks for LB-CPS

Research and Technology Objectives and Plans Summary (RTOPS)

A compilation of the summary portions of each of the Research and Technology Operating Plans (RTOP) used for management review and control of research currently in progress throughout NASA is presented along with citations and abstracts of the RTOPs. Indexes include: subject; technical monitor; responsible NASA organization; and RTOP number

Novel therapies for hypertension and associated cardiovascular risk

University of Minnesota Ph.D. dissertation. August 2018. Major: Biomedical Engineering. Advisor: Alena Talkachova. 1 computer file (PDF); xvii, 134 pages.This thesis is comprised of two parts. The first part investigates a novel therapy, vagus nerve stimulation, for hypertension and hypertension-induced heart disease. Hypertension impacts over 1 billion people worldwide, and clinical management is challenging. Left uncontrolled, high blood pressure can significantly increase the risk of cardiovascular events. The majority of hypertensive patients are treated with anti-hypertensive drugs to control blood pressure, but many limitations exist including resistant hypertension, inability to tolerate therapy, and non-compliance with the medication regime. For these patients, an alternative approach is needed to control blood pressure. Recently, the imbalance in the autonomic nervous system, evident in hypertension, has been the target of novel device-based therapies such as vagus nerve stimulation. The main goal of this research is to evaluate the efficacy of vagus nerve stimulation to treat hypertension and hypertension-induced heart disease. This thesis investigates the impact of vagus nerve stimulation on disease progression, survival, and cardiovascular remodeling in Dahl salt-sensitive hypertensive rats. Overall, the results of this work provide evidence for the beneficial therapeutic effects of vagus nerve stimulation in hypertension and motivate future studies to optimize therapy parameters and further understand therapeutic mechanisms. The second part of this thesis focuses on atrial fibrillation and the evaluation of new mapping techniques for improving rotor localization for ablation procedures. Currently, success rates for ablation procedures for non-paroxysmal atrial fibrillation are low and require repeat procedures or a lifetime of pharmacological agents to reduce the risk of stroke. Improved signal processing techniques for mapping electrical activity in the atrium can help further our understanding of the generation and maintenance of atrial fibrillation and ultimately improve ablation procedure success rates and terminate the arrhythmia. The main goal of this work was to validate new signal processing techniques – multiscale frequency, kurtosis, Shannon entropy, and multiscale entropy – to identify regions of abnormal electrical activity. The results of this work demonstrate improved accuracy of these novel techniques in mapping rotors in cardiac arrhythmias and motivates further studies evaluating more complex arrhythmias and human intracardiac electrograms