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This thesis focuses on the issues related to the implementation of theoretical timed discrete-event systems (TDES) supervisors. In particular, we examine issues related to implementing TDES as sampled-data (SD) controllers, which were introduced by Wang and Leduc. An SD controller is driven by a periodic clock and sees the system as a series of inputs and outputs. On each clock edge (tick event), it samples its inputs, changes state, and updates its outputs. / This thesis focuses on the issues related to the implementation of theoretical timed discrete-event systems (TDES) supervisors. In particular, we examine issues related to implementing TDES as sampled-data (SD) controllers, which were introduced by Wang and Leduc. An SD controller is driven by a periodic clock and sees the system as a series of inputs and outputs. On each clock edge (tick event), it samples its inputs, changes state, and updates its outputs. We first introduce the sampled-data setting from Wang, and then define the sampled-data properties he identified, including the SD controllability property. We then introduce Wang's formal representation of an SD controller as a Moore synchronous finite state machine (FSM). We then discuss Wang's modular and centralized translation method. We next introduced new modular results for the SD controllability point 3.1, SD controllability point 3.2, SD controllability point 4, activity loop free and S-singular prohibitable behaviour that allow one to verify the properties using only a portion of the system, instead of having to construct the entire system model. This should allow faster verification times as well as allow larger systems to be verified. We then introduce for the first time algorithms to verify Wang's CS Deterministic and non self-loop ALF properties. The remainder of the thesis focuses on developing algorithms and software to automatically convert a TDES first into an FSM, and then into a VERILOG module. VERILOG is a hardware description language which allows our FSM to be compiled and implemented on digital logic devices such as an FPGA. We then tested our method by modelling a simple door locking system as TDES, checking that the system satisfies the required sampled-data properties, and then translating the result into VERILOG. The above algorithms and methods have all been implemented as a part of the graphical DES research tool, DESpot. / Thesis / Master of Computer Science (MCS)

<p> Hierarchical Interface-based Supervisory Control (HISC) decomposes a discrete-event system (DES) into a high-level subsystem which communicates with n ≥ 1 low-level subsystems, through separate interfaces which restrict the interaction of the subsystems. It provides a set of local conditions that can be used to verify global conditions such as nonblocking and controllability. As each clause of the definition can be verified using a single subsystem, the complete system model never needs to be stored in memory, offering potentially significant savings in computational resources.</p> <p> Currently, a designer must create the supervisors for a HISC system himself, and then verify that they satisfy the HISC conditions. In this thesis, we develop a synthesis method that respects the HISC hierarchical structure. We replace the supervisor for each level by a corresponding specification DES. We then do a per level synthesis to construct for each level a maximally permissive supervisor that satisfies the corresponding HISC conditions.</p> <p> We define a set of language based fixpoint operators and show that they compute the required level-wise supremal languages. We then present algorithms that implement the fixpoint operators. We present a complexity analysis for the algorithms and show that they potentially offer significant improvement over the monolithic approach.</p> <p> A large manufacturing system example (estimated worst case state space on the order of 10^22) extended from the AIP example is discussed. A software tool for synthesis and verification of HISC systems using our approach was also developed.</p> / Thesis / Master of Applied Science (MASc)

This thesis focuses on issues related to implementing theoretical Discrete-Event Systems (DES) supervisors, and the concurrency and timing delay issues involved. Sampled-data (SD) supervisory control deals with timed DES (TDES) systems where the supervisors will be implemented as SD controllers. An SD controller is driven by a periodic clock and sees the system as a series of inputs and outputs. On each clock edge (tick event), it samples its inputs, changes states, and updates its outputs. In this thesis, we identify a set of existing TDES properties that will be useful to our work, but not sufficient. We extend the TDES controllability definition to a new definition, SD controllability, which captures several new properties that will be useful in dealing with concurrency issues, as well as make it easier to translate a TDES supervisor into an SD controller. We then establish a formal representation of an SD controller as a Moore Finite State Machine (FSM), and describe how to translate a TDES supervisor to a FSM, as well as necessary properties to be able to do so. We discuss how to construct a single centralized controller, as well as a set of modular controllers and show that they will produce equivalent output. Next, we capture the enablement and forcing action of a translated controller in the form of a TDES supervisory control map, and show that the closed-loop behavior of this map and the plant is the same as that of the plant and the original TDES supervisor. We also show that our method is robust with respect to nonblocking and certain variations in the actual behavior of our physical system. We also introduce a set of predicate-based algorithms to verify the SD controllability property, as well as certain other conditions that we require. We have created a software tool for verifying these conditions and provide the source code in the appendix. We have implemented these algorithms using binary decision diagrams (BDD). For illustrative purpose, we have produced a set of examples which fail the key conditions discussed in this thesis, as well as a successful application example based on a Flexible Manufacturing System. We also presented the corresponding FSM, translated from the example's supervisors. / Thesis / Master of Applied Science (MASc)

A system is described for identifying obstacle-free landing sites for a vertical-takeoff-and-landing (VTOL) semi-autonomous unmanned aerial vehicle (UAV) from point cloud data obtained from a stereo vision system. The relatively inexpensive, commercially available Bumblebee stereo vision camera was selected for this study. A "point cloud viewer" computer program was written to analyze point cloud data obtained from 2D images transmitted from the UAV to a remote ground station. The program divides the point cloud data into segments, identifies the best-fit plane through the data for each segment, and performs an independent analysis on each segment to assess the feasibility of landing in that area. The program also rapidly presents the stereo vision information and analysis to the remote mission supervisor who can make quick, reliable decisions about where to safely land the UAV. The features of the program and the methods used to identify suitable landing sites are presented in this thesis. Also presented are the results of a user study that compares the abilities of humans and computer-supported point cloud analysis in certain aspects of landing site assessment. The study demonstrates that the computer-supported evaluation of potential landing sites provides an immense benefit to the UAV supervisor. / Master of Science

This research is a descriptive, correlational study investigating mathematics teachers' perceptions of their self-efficacy and the effects of teacher characteristics and supervisory behaviors on teachers' self-efficacy. Teachers who teach mathematics from an urban school district in the southern part of the United States were asked to report on their self-efficacy in teaching mathematics and their perception of the supervisory behaviors that support the development of their self-efficacy. The study sought to determine the relationship between teachers of mathematics self-efficacy and the characteristics and supervisory behaviors that foster the development of their self-efficacy. Gender, ethnicity, years of mathematics teaching, level of education, and years at current school are used as control variables. The study findings suggest instructional leaders need to use a variety of strategies to enhance teacher efficacy. Strategies that were reported to be particularly useful included those that foster teacher collaboration, autonomy, and empowerment. Ensuring appropriate systems, services, and support for teacher collaboration should be a priority for those in leadership positions. An important practical implication emerging from this research is the need for feedback. It is expected that the results of this research may benefit educational supervisors when they consider which type of supervision and supportive actions to adopt to foster the development of mathematics self-efficacy in their teachers. / Doctor of Education / This research is designed to investigate mathematics teachers' perceptions of their self-efficacy and the effects of teacher characteristics and supervisory behaviors on teachers’ self-efficacy. The study is threefold: (a) to explore the self-efficacy of teachers who teach mathematics, (b) to identify teacher characteristics and supervisory behaviors that teachers perceived affect teacher self-efficacy, and (c) to determine whether there is a relationship between the mathematics supervisory behaviors and teacher self-efficacy as seen by the teachers, while controlling for gender, ethnicity, years of mathematics teaching, level of education, and years at current school. Teachers who teach mathematics from an urban school district in the southern part of the United States were asked to report on their self-efficacy in teaching mathematics and their perception of the supervisory behaviors that support the development of their self-efficacy. The study findings suggest instructional leaders need to use a variety of strategies to enhance teacher efficacy. Strategies that were reported to be particularly useful included those that foster teacher collaboration, autonomy, and empowerment. Ensuring appropriate systems, services, and support for teacher collaboration should be a priority for those in leadership positions. An important practical implication emerging from this research is the need for feedback. It is expected that the results of this research may benefit educational supervisors when they consider which type of supervision and supportive actions to adopt to foster the development of mathematics self-efficacy in their teachers. Keywords: Self-efficacy, Supervisory behaviors, Mathematics Teachers, Perceptions of Self-efficacy, Teacher Characteristics

Faculty mentorship is considered an important component of graduate education. Faculty supervisors of graduate student assistants are in a unique position to enhance the personal and career development of their supervisees. Yet, little is known about the relationship between supervision and mentorship in graduate education. The purpose of this study was to explore the relationship between mentoring behavior and supervisory approach as reported by faculty supervisors of graduate student assistants at Virginia Tech. Data were collected using the Mentor Behaviors Questionnaire and Supervisory Approach Inventory and analyzed using analysis of variance. The findings suggested that faculty provided career mentoring behaviors as a result of academic culture and the perceived role of faculty rather than the influence of gender, prior mentoring experience, or length of relationship. However, faculty with no prior mentoring experience, might be unaware of the value of psychosocial mentoring in promoting personal development of their assistants, especially in male-male relationships. A positive relationship between synergistic supervision and mentoring was established which suggested that productive supervisory practices and mentoring behavior were similar. Faculty who had more contact with students reported higher levels of career mentoring. Reward and recognition were suggested as incentives for increasing student contact which might foster career mentoring. Surprisingly, graduate assistant supervisors reported higher rates of mentoring behaviors than teaching or research assistant supervisors, thus challenging the commonly held perception that research assistants were more likely to receive mentoring support from faculty than other types of assistants. The information generated by this study is useful in identifying faculty behaviors associated with mentorship and establishing the link between assistantship supervision and mentorship opportunity. Student affairs and graduate education professionals may find that the implementation of faculty mentor training programs is a useful tool in promoting the psychosocial and career development of students. / Master of Arts

The electrical distribution system in the United States is considered one of the most complicated machines in existence. Electrical phenomena in such a complex system can inflict serious self-harm. This requires damage prevention from protection schemes. Until recently, there was a safe gap between capacity to deliver power and the demand. Therefore, these protection schemes focused on dependability allowing the disconnection of lines, transformers, or other devices with the purpose of isolating the faulted element. On some occasions, the disconnections made were not necessary. The other extreme of reliability calls for security. This aspect of reliability calls for the operation of the protective devices only for faults within the intended area of protection. There is a tradeoff here; where a dependable protection scheme will assuredly prevent damage, it is prone to unnecessary operation which can lead to cascading outages. Where a secure scheme will not operate unnecessarily, it is prone to pieces of the system becoming damaged when relays fail to operate properly. With microprocessor based relaying schemes, a hybrid reliability focus is attainable through adaptive relaying. Adaptive relaying describes protection schemes that adjust settings and/or logic of operations based on the prevailing conditions of the system. These adjustments can help to avoid relay miss-operation. Adjustments could include, but are not limited to, the logging of data for post-mortem analysis, communication throughout the system, as well changing relay parameters. Several concepts will be discussed, one of which will be implemented to prove the value of the new tools available. / Master of Science

Yes / This study examines the impact of multi-layer governance mechanisms on the level of bank risk disclosure. Using a large dataset from 14 Middle East and North Africa (MENA) countries over a period of 8 years, our findings are three-fold. First, our results suggest that the presence of a Sharia supervisory board is positively associated with the level of risk disclosure. Second and at the bank-level, we find that ownership structures have a positive effect on the level of risk disclosure. At the country-level, our evidence suggests that control of corruption has a positive effect on the level of bank risk disclosure. Our study is, therefore, a major departure from much of the existing accounting literature that offers new crucial insights that show that firms’ disclosure choices are not mainly shaped by firm-level (internal) governance arrangements, but also country-level (external) governance and religious factors. Our findings have important implications for corporate boards, investors, regulatory authorities, standards-setters and governments relating to the development, implementation and enforcement of corporate and national governance standards.