Mechanistic-based Design-Integrated Reliability Validation Framework for Mechanical Systems

Abstract: New product design challenges, related to customer needs, product usage and environments, face companies when they expand their product offerings to new markets; Some of the main challenges are: the lack of quantifiable information, product experience and field data. Designing reliable products under such challenges requires flexible reliability assessment processes that can capture the variables and parameters affecting the product overall reliability and allow different design scenarios to be assessed. These challenges also suggest a mechanistic (Physics of Failure-PoF) reliability approach would be a suitable framework to be used for reliability assessment. Mechanistic Reliability recognizes the primary factors affecting design reliability. This research views the designed entity as a “system of components required to deliver specific operations”; it addresses the above mentioned challenges by; Firstly: developing a design synthesis that allows a descriptive operations/ system components relationships to be realized; Secondly: developing component’s mathematical damage models that evaluate components Time to Failure (TTF) distributions given: 1) the descriptive design model, 2) customer usage knowledge and 3) design material properties; Lastly: developing a procedure that integrates components’ damage models to assess the mechanical system’s reliability over time. Analytical and numerical simulation models were developed to capture the relationships between operations and components, the mathematical damage models and the assessment of system’s reliability. The process was able to affect the design form during the conceptual design phase by providing stress goals to meet component’s reliability target. The process was able to numerically assess the reliability of a system based on component’s mechanistic TTF distributions, besides affecting the design of the component during the design embodiment phase. The process was used to assess the reliability of an internal combustion engine manifold during design phase; results were compared to reliability field data and found to produce conservative reliability results. The research focused on mechanical systems, affected by independent mechanical failure mechanisms that are influenced by the design process. Assembly and manufacturing stresses and defects’ influences are not a focus of this research.

Motion Planning and Controls with Safety and Temporal Constraints

Motion planning, or trajectory planning, commonly refers to a process of converting high-level task specifications into low-level control commands that can be executed on the system of interest. For different applications, the system will be different. It can be an autonomous vehicle, an Unmanned Aerial Vehicle(UAV), a humanoid robot, or an industrial robotic arm. As human machine interaction is essential in many of these systems, safety is fundamental and crucial. Many of the applications also involve performing a task in an optimal manner within a given time constraint. Therefore, in this thesis, we focus on two aspects of the motion planning problem. One is the verification and synthesis of the safe controls for autonomous ground and air vehicles in collision avoidance scenarios. The other part focuses on the high-level planning for the autonomous vehicles with the timed temporal constraints. In the first aspect of our work, we first propose a verification method to prove the safety and robustness of a path planner and the path following controls based on reachable sets. We demonstrate the method on quadrotor and automobile applications. Secondly, we propose a reachable set based collision avoidance algorithm for UAVs. Instead of the traditional approaches of collision avoidance between trajectories, we propose a collision avoidance scheme based on reachable sets and tubes. We then formulate the problem as a convex optimization problem seeking control set design for the aircraft to avoid collision. We apply our approach to collision avoidance scenarios of quadrotors and fixed-wing aircraft. In the second aspect of our work, we address the high level planning problems with timed temporal logic constraints. Firstly, we present an optimization based method for path planning of a mobile robot subject to timed temporal constraints, in a dynamic environment. Temporal logic (TL) can address very complex task specifications such as safety, coverage, motion sequencing etc. We use metric temporal logic (MTL) to encode the task specifications with timing constraints. We then translate the MTL formulae into mixed integer linear constraints and solve the associated optimization problem using a mixed integer linear program solver. We have applied our approach on several case studies in complex dynamical environments subjected to timed temporal specifications. Secondly, we also present a timed automaton based method for planning under the given timed temporal logic specifications. We use metric interval temporal logic (MITL), a member of the MTL family, to represent the task specification, and provide a constructive way to generate a timed automaton and methods to look for accepting runs on the automaton to find an optimal motion (or path) sequence for the robot to complete the task.

Antonio Salieri's La calamita de' cuori (1774): Sources, Form, Context

Antonio Salieri’s La calamita de’ cuori (1774) warrants musicological attention for what it can tell us about Salieri’s compositional craft and what it reveals about the development of form in Viennese Italian-language comic opera of the mid- and late-eighteenth century. In Part I of this dissertation, I explore the performance history of La calamita, present the first plot synopsis and English translation of the libretto, and describe the variants between Carlo Goldoni’s 1752 libretto and the revised version created for Salieri’s opera. I have collated Salieri’s holograph score, Österreichische Nationalbibliothek, Vienna, Mus. Hs. 16.508, with four copies having different relationships to it, and I propose a stemma that represents the relationships between these five sources. The analyses in Part II contribute to our understanding of formal practices in eighteenth-century drammi giocosi. My study of Salieri’s La calamita reveals his reliance on a clearly defined binary structure, referred to in this dissertation as “operatic binary form,” in almost half of the arias, ensembles, and instrumental movements of this opera. Salieri’s consistent use of operatic binary form led me to explore its use in drammi giocosi by other prominent composers of this time, including Baldassare Galuppi’s La calamita de’ cuori (1752), Wolfgang Amadeus Mozart’s Il dissoluto punito, ossia Il Don Giovanni (1787), and selected arias by Pasquale Anfossi, Florian Leopold Gassmann, Giuseppe Gazzaniga, Franz Joseph Haydn, Giovanni Paisiello, and Niccolò Piccinni dating from 1760 to 1774. This study showed that Salieri and his peers adhered to a recognizable tonal plan and set of design elements in their operatic binary forms, and that their arias fall into three distinct categories defined by the tonality at the beginning of the second half of the binary structure. The analysis presented here adds to our present understanding of operatic form in mid- and late-century drammi giocosi and shows that in La calamita de’ cuori, Salieri was following the normative formal procedures of his time.