Studies on Metallization of RP Parts for use in Preserving Artefacts

Properties like easy formability, light weight and corrosion resistance constitute natural advantage of plastic over metal. However, there are many areas in which metallic properties are required or demanded due to decorative or technological considerations. It is in these applications that the possibility of metallizing plastics has opened the door to new use for these materials. Metallization is a process in which a non-conductive material such as plastic is made conductive by providing a conductive layer on it. Due to this, possibility of utilizing the advantages of both metal and plastic in combination has been increased. As a result metallized plastic is widely used in fields like oil and gas, automotive industry, electronic industry, chemical processing, textile, aerospace, providing finishes on fashion items such as shoes, name badges, as well as on consumer electronics products including laptop cases and cell phones etc. Plastics such as polysulfone, polypropylene, polythene, teflon and acrylonitrile-butadiene-styrene (ABS) can be metalized with different metals like copper (Cu), zinc (Zn), nickel (Ni), gold (Au), chromium (Cr) and silver (Ag) using variety of processes like brushing a metal paint, spray metal technique, dipping in a metal paint, sputtering, electroplating, electroless plating and vacuum metallization. Among these processes, electroplating is widely used because of its simplicity and economy. In this method, metal ions in aqueous solutions are deposited on the activated plastic surface by an electro-chemical reaction with the aid of an electric potential, forming a thin metallic layer. In this work, possibility of metallization on RP parts through electroplating route has been explored for preserving artefacts

Conceptual-Level Analysis and Design of Unmanned Air Traffic Management Systems

There have been multiple announcements by different companies in the past couple years of package delivery by drone and air taxi projects. However, there are still many barriers to the deployment of high densities of aerial vehicles in low-altitude airspace over urban areas. Current Air Traffic Control Systems cannot handle the high density of traffic being forecast. Integrating these new types of on-demand air mobility in the National Airspace requires a fundamental change to the traffic management system. Many different concepts of operations for unmanned traffic management (UTM) systems have been proposed, but there is no common framework to evaluate and compare alternatives at a conceptual design stage. This might cause a locally optimal system to be chosen, resulting in lower safety and economic performance than what would have been possible if a more systematic approach to the design of UTM system had been followed. In this thesis, a systematic approach to the design of UTM systems is introduced. Based on the literature on conceptual design, a five step approach to the design of UTM systems is proposed. The steps of the approach are: define operating scenarios, generate UTM alternatives, select performance criteria, evaluate, and make decision. To generate UTM alternatives in a systematic manner, a matrix of alternatives should be created. However, this requires a system decomposition that does not currently exist for UTM systems. Here, a system decomposition into four subsystems is proposed: airspace structure, access control, preflight planning, and collision avoidance. For each subsystem, alternatives are identified using the literature. For the second step of the approach, operating scenarios for UTM are not well-defined. There are many external factors outside of the designer’s control, and different studies make different assumptions. Three different external factors, or components of an operating scenario, are identified: demand, static obstacles, and priority traffic. The impact of the different subsystems and external factors on the performance of a given UTM architecture cannot be found in the literature. Many studies evaluate a point design or fix assumptions to focus on a single subsystem. There is no available tool that allows to evaluate different UTM architectures while varying all the elements that have been presented here. To bridge that gap, an agent-based simulation was developed to allow the evaluation of the UTM systems generated using the matrix of alternatives in different operating scenarios. For the fourth step of the approach, performance criteria are selected from the aviation literature. To capture safety, the number of losses of separation and near-midair-collisions per flight hour are used. To measure the efficiency of the trajectories, a time and energy efficiency metrics are introduced. The capacity of the system is evaluated for a fixed overall density using the throughput, or number of vehicles completing a flight per minute. Finally, two simple multi-attribute decision making methods are selected from the literature. This allows to rank architectures based on their performance in a given scenario for a given set of weights representing a designer’s preferences. This thesis also proposes a novel 4D trajectory planning algorithm that relies on a local collision avoidance method. Experiments show that it performs well in terms of time efficiency and throughput when compared to a decoupled approach. The novel algorithm achieves a comparable performance to a global optimization algorithm in a nominal cruise scenario but is much more computationally efficient. The impact of the inclusion of certain subsystems and external factors on the outcome of the conceptual design stage is systematically evaluated in a series of experiments. Performance of different architectures is evaluated with and without the subsystem or external factor of interest. The experiments show that there are significant interactions between agents' autonomous behaviors, airspace structure, and external factors such as demand, static obstacles, and priority traffic. The decision tables obtained with and without the element of interest are compared, and weights are found such that the architecture rankings are different. This shows that neglecting these interactions or making simplifying assumptions may change the outcome of the conceptual design stage and result in the selection of an architecture that underperforms in terms of safety, capacity or efficiency. This is validated on two use cases, an air taxi scenario and a drone delivery scenario. In the air taxi scenario, using the proposed approach results in the selection of an alternative with a 25\% higher score than the alternative selected with a baseline approach. As a result of the work conducted in this thesis, the importance of including the autonomy, airspace structure, demand, static obstacles, and priority traffic in the early stage of UTM evaluation has been demonstrated. The necessity of including other subsystems or external factors can be evaluated by following the same process that was demonstrated in the thesis.Ph.D

Coronary angioscopy

Coronary angioscopy will not replace angiography as the gold standard for imaging atherosclerotic coronary arteries. However, there may well be a clinical niche for a technology that gives accurate information regarding a specific lesion, if that information can be used to improve the acute or chronic outcome of an interventional procedure. Our experience demonstrates that angioscopy indeed provides this information. Using angioscopy, we now have access to information regarding arterial wall disease that heretofore has been available only at necropsy. In addition, whereas angiography has provided only a 2-dimensional, gray-scale image of the coronary vessels, angioscopy offers a full-color, 3-dimensional perspective of the intracoronary surface morphology. These important lesion-specific details, not reliably available from angiography alone, may ultimately be used to improve patient outcome and to assess risk

The Social Contract Theory in the Face of Empirical Morality: Integration and Its Consequences

The following study experimentally investigated moral attitudes, both intuitive and reasoned, to assess the validity of the social contract theories of four prominent thinkers: Thomas Hobbes, John Locke, Jean-Jacques Rousseau, and John Rawls. These social contract thinkers, though different in their proposals, all attempt to provide an answer to one long-withstanding question: which governmental structure is best? Their theories also interweave moral cognition with the governmental structure recommended. Thus, this research endeavored to contribute to the contemporary discussion of the social contract theory, encourage empirical investigation of the social contract theory, and provide a framework for future research of a similar kind in order to answer such a question. The research was conducted in survey format with two modules and the data collected was analyzed through evaluation of each section. Module 1, moral consistency, is the quantitative portion of the experimental design which assessed whether or not there was a consistency amongst respondents’ intuitions. Module 2, moral compatibility, is the qualitative portion of the experimental design which considered whether respondents’ moral intuitions and moral reasoning align or not and assigned each respondent’s moral reasoning responses to a thinker based on their method of reasoning. The data was then considered within the framework of the social contract theories presented in order to determine which theory the data best supported. The hypothesis put forth was that, given previous and distinct scholarship on the issues of the social contract theory and moral cognition, that Rawls would represent the majority in both modules of the experiment. However, the empirical results supported Lockeian theory most favorably in both modules, and the weight of such a conclusion considered in the context of practical politics. A discussion is then had on the complications such results pose for moral and political theory, and further experimentation encouraged

Analysis of Weather-Related Helicopter Accidents and Incidents in the United States

Presented at AIAA Aviation 2021 ForumHelicopters typically operate at lower altitudes than fixed-wing aircraft and can take-off and land away from airports. Thus, helicopter pilots have decreased access to weather information due to connectivity issues or sparsity of weather coverage in those areas and at those altitudes. Moreover, regulations allow most rotorcraft to operate in marginal weather conditions. Therefore, weather is a challenge to rotorcraft operations. In this study, rotorcraft events in the United States between 2008 and 2018 in which weather was determined to be a factor are analyzed using the National Transportation Safety Board aviation database. Results show that weather was a factor in 28% of rotorcraft fatal accidents. Wind was involved in most incidents but more rarely involved in fatalities. Bad visibility conditions due to a combination of low illumination and clouds were responsible for most fatal weather-related accidents. Personal flights had the highest accident and incident rates. Finally, the Helicopter Air Ambulance industry had the largest number of incidents and accidents related to visibility conditions out of all other industries. The authors recommend improving awareness of the conditions in which weather events occur and improving training to maintain control of the aircraft in windy conditions or during inadvertent instrument meteorological conditions

ProNGF Induces p75-Mediated Death of Oligodendrocytes following Spinal Cord Injury

AbstractThe neurotrophin receptor p75 is induced by various injuries to the nervous system, but its role after injury has remained unclear. Here, we report that p75 is required for the death of oligodendrocytes following spinal cord injury, and its action is mediated mainly by proNGF. Oligodendrocytes undergoing apoptosis expressed p75, and the absence of p75 resulted in a decrease in the number of apoptotic oligodendrocytes and increased survival of oligodendrocytes. ProNGF is likely responsible for activating p75 in vivo, since the proNGF from the injured spinal cord induced apoptosis among p75+/+, but not among p75−/−, oligodendrocytes in culture, and its action was blocked by proNGF-specific antibody. Together, these data suggest that the role of proNGF is to eliminate damaged cells by activating the apoptotic machinery of p75 after injury