Acousto-elastic interaction in combustion chambers

This thesis deals with the interaction between combustion, acoustics and vibrations with emphasis on frequencies below 500 Hz. Extensive literature is available on the interaction between combustion and acoustics and much work is also available on the interaction between acoustics and vibration. The work presented in this thesis attempts to combine these fields in order to calculate the vibrations of the liner

Two Octopuses Making Love: An Analysis of Institutional Management Behaviors Across Four Brownfield Remediation and Redevelopment Project Networks in Rochester and Buffalo, NY

With intensifying pressure to not only solve public problems by collaborating with actors situated outside the confines of city hall but also to address complex, long-term challenges like climate change adaptation and sustainability, local government public managers find themselves working in increasingly difficult public management environments. Currently, public management theory fails to fully prescribe management strategies and behaviors that enable managers to best achieve their goals in these situations. This dissertation addresses this gap between theory and practice by tracing the public management processes that lead to outcomes in a set of municipality-led brownfield remediation and redevelopment projects. Utilizing an integration of public management, policy tool, and network theories, this research compares four project-level case studies in Rochester and Buffalo, New York, to address two primary questions. First, in what ways do brownfield projects function as public management networks? Second, to what extent do network management behaviors by city-level public managers impact project outcomes? Contrary to prior research, my findings revealed that neither relationship management nor policy tool strategies alone sufficiently explained project outcomes. Instead, effective public management occurred when high levels of political legitimacy were coupled with an integration of policy tool and relationship management strategies, either through network-centric public managers themselves or through the actions of political champions operating in partnership with them. These findings imply that public management researchers focusing solely upon relationship management or policy tool explanations separate from political influences are not fully capturing the true public management story

The Optimisation of Stochastic Grammars to Enable Cost-Effective Probabilistic Structural Testing

The effectiveness of probabilistic structural testing depends on the characteristics of the probability distribution from which test inputs are sampled at random. Metaheuristic search has been shown to be a practical method of optimis- ing the characteristics of such distributions. However, the applicability of the existing search-based algorithm is lim- ited by the requirement that the software’s inputs must be a fixed number of numeric values. In this paper we relax this limitation by means of a new representation for the probability distribution. The repre- sentation is based on stochastic context-free grammars but incorporates two novel extensions: conditional production weights and the aggregation of terminal symbols represent- ing numeric values. We demonstrate that an algorithm which combines the new representation with hill-climbing search is able to effi- ciently derive probability distributions suitable for testing software with structurally-complex input domains

Situation Coverage Testing for a Simulated Autonomous Car -- an Initial Case Study

It is hard to test autonomous robot (AR) software because of the range and diversity of external situations (terrain, obstacles, humans, peer robots) that AR must deal with. Common measures of testing adequacy may not address this diversity. Explicit situation coverage has been proposed as a solution, but there has been little empirical study of its effectiveness. In this paper, we describe an implementation of situation coverage for testing a simple simulated autonomous road vehicle, and evaluate its ability to find seeded faults compared to a random test generation approach. In our experiments, the performance of the two methods is similar, with situation coverage having a very slight advantage. We conclude that situation coverage probably does not have a significant benefit over random generation for the type of simple, research-grade AR software used here. It will likely be valuable when applied to more complex and mature software

Factors Affecting Faculty Use of Video Conferencing in Teaching: A Mixed-method Study

Teaching and learning can now utilize a variety of real-time technologies to build online social presence and learning interactions. However, teachers and students must effectively prepare for this experience; and the identification of contextual and perceptual influences become evolving and necessary (Lehman & Conceição, 2010; Liu & Kaye, 2016). In this paper, the authors explore factors that impact faculty use of synchronous video conferencing (VC) in teaching. The two-phase mixed-method study spanned a year, converging qualitative and quantitative approaches through observations and recordings during a 6-week faculty professional development program, a campus-wide survey, and focus groups. Thematic analysis was used for coding qualitative data (Guest, MacQueen, & Namey, 2012). Descriptive statistics, cross tabulation, logistic regression, and standard multiple regression were used to analyze quantitative data. A model with faculty demographic factors and perceived importance of technology features and quality for teaching was initially developed and tested, which explained 69.1% of the variance in predicting faculty use of VC technologies in teaching. The perceived importance of VC features and quality scale generated Cronbach’s Alpha .866. The study then provides meaningful process and recommendations to define institutional support to the VC adoption in teaching

Enhancing Covid-19 Decision-Making by Creating an Assurance Case for Simulation Models

Simulation models have been informing the COVID-19 policy-making process. These models, therefore, have significant influence on risk of societal harms. But how clearly are the underlying modelling assumptions and limitations communicated so that decision-makers can readily understand them? When making claims about risk in safety-critical systems, it is common practice to produce an assurance case, which is a structured argument supported by evidence with the aim to assess how confident we should be in our risk-based decisions. We argue that any COVID-19 simulation model that is used to guide critical policy decisions would benefit from being supported with such a case to explain how, and to what extent, the evidence from the simulation can be relied on to substantiate policy conclusions. This would enable a critical review of the implicit assumptions and inherent uncertainty in modelling, and would give the overall decision-making process greater transparency and accountability.Comment: 6 pages and 2 figure