Ceramics have a wide variety of applications due to their unique properties; however, the low fracture toughness leads the formation and propagation of unpredictable cracks, and reduces their reliability. To solve this problem, self-healing adaptive oxides were developed. The aim of the work is to gain new insights into self-healing mechanisms of ceramics and their application. Binary oxide systems were investigated that are at least partially healed through the extrinsic or intrinsic addition of silver or silver oxide to form ternary oxides (e.g., Nb2O5 + Ag → AgNbO3). Sintered pellets and coatings were tested. For self-healing TBCs, model systems that were studied include YSZ-Al2O3-SiC, YSZ-Al2O3-TiC, YSZ-Al2O3-Nb2O5, and YSZ-Al2O3-Ta2O5. Laser cladded samples and sintered pellets were produced to test. The healing process occurs due to the formation of oxidation products and glassy phases depending on the self-healing mechanism. X-ray diffraction was used to explore phase evolution, chemical compositions, and structural properties of these samples. SEM equipped with EDS was used to investigate the chemical and morphological properties for the cross-sectional area. Pin-on-disc test was applied to test tribology performance for Nb2O5-Ag2O system, and infiltration test was applied to test CMAS-resistance for TBCs at elevated temperature. The improvements in the performance of these materials were demonstrated.

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A thesis submitted in fulfillment of the requirements for the degree of Master of Arts in Communication Science at the University of Zululand, South Africa, 2012. / Relationship in banking has become very competitive in the recent past, more especially in the aftermath of the recent global economic meltdown. Most of the major banks in South Africa are not only striving to improve the quality and quantity of their clientele but also to maintain their survival in the corporate market. Most relationship in banks focus on customer satisfaction and customer loyalty, however, the issue of language barrier is being neglected in many banking halls. South Africa hosts eleven official languages and it is obviously not feasible for one particular bank to embrace all these languages for customer service, however, there can be varied strategies for individual banks to cater for clients in specific locations. This thesis examines how particular banks cater for the language needs of its immediate community. The primary goal of this study is to examine the current quality of service offered by the banking sector in South Africa especially in terms of service delivery proposed by the banking code of practice (ABSA COBP).The clients and staff of a bank in Zululand (KwaZulu-Natal) provided valuable information for this study. The data was collected through the use of structured interviews of clients and staff members. The study is informative and insightful in that it infiltrates the responsibilities policy makers in communicating with clients. Furthermore, the study exposes provocative and controversial issues in communication policy and hopes to stir awareness within the banking sector to improve relationship banking. This ground-breaking study also demonstrates how challenges faced by the clients cause banks to fail to meet its intended purpose. This study also exposes provocative and controversial challenges which place our banking sector at risk of total annihilation if left unattended. The study speaks to issues of accountability such as: planning and decision making and the plight of the people of our nation.

abstract: Two-sided online platforms are typically plagued by hidden information (adverse selection) and hidden actions (moral hazard), limiting market efficiency. Under the context of the increasingly popular online labor contracting platforms, this dissertation investigates whether and how IT-enabled monitoring systems can mitigate moral hazard and reshape the labor demand and supply by providing detailed information about workers’ effort. In the first chapter, I propose and demonstrate that monitoring records can substitute for reputation signals such that they attract more qualified inexperienced workers to enter the marketplace. Specifically, only the effort-related reputation information is substituted by monitoring but the capability-related reputation information. In line with this, monitoring can lower the entry barrier for inexperienced workers on platforms. In the second chapter, I investigate if there is home bias for local workers when employers make the hiring decisions. I further show the existence of home bias from employers and it is primarily driven by statistical inference instead of personal “taste”. In the last chapter, I examine if females tend to have a stronger avoidance of monitoring than males. With the combination of the observational data and experimental data, I find that there is a gender difference in avoidance of monitoring and the introduction of the monitoring system increases the gender wage gap due to genders differences in such willingness-to-pay for the avoidance of monitoring. These three studies jointly contribute to the literature on the online platforms, gig economy and agency theory by elucidating the critical role of IT-enabled monitoring. / Dissertation/Thesis / Doctoral Dissertation Business Administration 2019

More motorcyclists are fatally injured each year in guardrail crashes than passengers of any other vehicle, while only accounting for three percent of the vehicle fleet. Since motorcyclists account for a high percentage of these fatalities, the goal of zero deaths on the road cannot be achieved without addressing the safety of motorcyclists. The objective of this research was to determine the factors that lead to serious or fatal injury in motorcycle barrier crashes, given that a crash occurred. The likelihood of serious or fatal injury in barrier crashes was significantly influenced by both barrier type and rider trajectory after striking the barrier. A national study of motorcyclist fatality risk using the Fatality Analysis Reporting System (FARS) and General Estimates System (GES) showed that crashes with guardrail than crashes were about 7 times more likely to be fatal than those with the ground, based on the most harmful event reported. An analysis of 1,000 riders in barrier crashes in three states showed that the odds of serious injury were 1.4 times greater in guardrail crashes than in concrete barrier crashes. These analyses did not take into account the trajectory of the rider after striking the barrier, since this was unknown. The police accident report for 350 barrier crashes in New Jersey was used to determine the rider trajectory in those crashes. Being ejected from the motorcycle after impacting the barrier significantly increased the odds of serious injury over crashes where the rider was not ejected. While providing insight into factors influencing injury severity, these analyses do not provide an understanding of the nature of injuries incurred in these crashes. To further understand how injuries were caused in motorcycle-barrier crashes, we developed a methodology for determining injury mechanisms in motorcycle-barrier collisions. Using this methodology, we investigated 9 serious motorcycle-to-barrier crashes. In these crashes, as well as in an analysis of 106 barrier crashes in Maryland, the thorax and lower extremities most commonly suffered serious injury. Of particular concern are the posts and top of the rail, both of which can lead to lacerations and blunt trauma. / Ph. D.

In this thesis we modified a sampling-based motion planning algorithm to improve sampling efficiency. First, we modify the RRT* motion planning algorithm with a local motion planner that guarantees collision-free state trajectories without explicitly checking for collision with obstacles. The control trajectories are generated by solving a sequence of quadratic programs with Control Barrier Functions (CBF) constraints. If the control trajectories satisfy the CBF constraints, the state trajectories are guaranteed to stay in the free subset of the state space. Second, we use a stochastic optimization algorithm to adapt the sampling density function of RRT* to increase the probability of sampling in promising regions in the configuration space. In our approach, we use the nonparametric generalized cross-entropy (GCE) method is used for importance sampling, where a subset of the sampled RRT* trajectories is incrementally exploited to adapt the density function. The modified algorithms, the Adaptive CBF-RRT* and the CBF-RRT*, are demonstrated with numerical examples using the unicycle dynamics. The Adaptive CBF-RRT* has been shown to yield paths with lower cost with fewer tree vertexes than the CBF-RRT*. / 2022-03-27T00:00:00Z

Tea is China's traditional export-earning agricultural product. For a long time, China's tea exports have occupied an extremely important position in the international market. With the further opening of the international agricultural product market and the increasingly fierce competition in the international tea market, China's tea exports are increasingly being affected by technical barriers.The purpose of this paper is to empirically analyze which factors are affecting Chinese green tea exports. In addition, there is a focus on the trade status of Chinese green tea in the EU market, Japan and the United States. To achieve this objective, this paper adopts a modern approach to gravity models, i.e. an approach which uses specifications based on micro-foundations. Specifically, The paper uses a specification which explicitly takes into account the nature of multilateral trade resistance (MTR). More specifically, estimators based on traditional panel methods (combined with the recommended structures of dummies) and Silva-Tenreyro's (2006) PPML estimator (also combined with dummies). The results show that the maximum residue limits(MRL) of pesticides in importing countries have significantly impacted the export of Chinese tea. The cultural effects such as the Language similarity have a positive...

The rising levels of autonomy exhibited by complex cyber-physical systems have brought questions related to safety and adaptation to the forefront of the minds of controls and robotics engineers. Often, such autonomous systems are deemed to be safety-critical in the sense that failures during operation could significantly harm the system itself, other autonomous systems, or, in the worst-case, humans interacting with such a system. Complicating the design of control and decision-making algorithms for safety-critical systems is that they must cope with various degrees of uncertainty as they are deployed autonomously in increasingly real-world environments. These challenges motivate the use of learning-based techniques that can adapt to such uncertainties while adhering to safety-critical constraints. The main objective of this dissertation is to present a unified framework for the design of controllers that learn from data online with formal guarantees of safety. Rather than using a controller trained on an a priori dataset collected offline that is then statically deployed on a system, we are interested in using real-time data to continuously update the control policy online and cope with uncertainties that are challenging to characterize until deployment. We approach the problem of designing such learning-based control algorithms for safety-critical systems through the use of certificate functions, such as Control Lyapunov Functions (CLFs) and Control Barrier Functions (CBFs), from nonlinear control theory. To this end, we first discuss how modern data-driven techniques can be integrated into traditional adaptive control frameworks to develop classes of CLFs and CBFs that facilitate the design of both controllers and learning algorithms that guarantee, respectively, stability and safety by construction. Next, we shift from the problem of safe adaptive control to safe reinforcement learning where we demonstrate how similar ideas from adaptive control can be extended to safely learn the value functions of optimal control problems online using data from a single trajectory. Finally, we discuss an extension of the aforementioned approaches to richer control specifications given in the form of temporal logic formulas, which provide a formal way to express complex control objectives beyond that of stability and safety. / 2025-05-30T00:00:00Z

The Mississippi and Alabama barrier islands are sensitive landforms that are affected by hurricanes, longshore currents, and available sediment, yet these effects are difficult to quantify with traditional ground-based surveying. In this study, Landsat satellite imagery was used to evaluate changes in barrier island area and centroid position from 1990 and 2005. When hurricanes are infrequent (1999?2003), barrier islands generally increased in total area and showed only moderate repositioning of their centroid locations. However, when hurricanes were frequent (1994?1999 and 2004?2005), barrier islands showed substantial decreases in area and dramatic repositioning of their island centroid locations. This was especially true following Hurricane Katrina (2005). From 1990 to 2005, the general movement of barrier islands was westerly and most islands experienced an overall reduction in area (-18%). The results of this research are similar to findings reported in the literature and illustrate the suitability of using Landsat imagery to study geomorphic changes.

Many cities focus on cycling due to the multiple advantages including individual, societal, and economic advantages. Eskilstuna municipality in Sweden is one of the cases that aim to develop cycling, but the question is if the municipality has managed in developing winter cycling because of the special winter weather characteristics, cold, windy, snowy, and dark. This study focuses on the experiences of commuters when commuting in winter in Eskilstuna municipality. The goal of this study is to identify and analyze the motivators and barriers that influence winter cycle commuting, and the research result can contribute to improving the cycling rate in Eskilstuna municipality. The researcher examined the issues in Eskilstuna municipality through qualitative analysis from the focus group interview and interview and document analysis. Factors such as prioritized cycle lanes, the construction of new cycle lanes, preference for wellbeing, social influence (such as cycling culture and cycle-friendly atmosphere), the good function of the cycle (including the cycle, the tire, the cycle lights), good private economy situation were identified as motivators to cycling to work in winter. By contrast, issues that are related to lack of infrastructure maintenance and lack of cycle lanes, the darkness, the snow, limitation in practices of the policy, and cleanness as a social norm were identified as barriers. However, some factors were identified as irrelevant factors such as low temperature, showing room, parking space, and scenery.