Master of Science

Safety concerns have been keeping autonomous vehicles off the roads for decades, although the main drivers for introducing some autonomy are to increase safety, reduce congestion, and greenhouse gas emissions. Safety is a vast topic that includes the safety of the system alone, known as string stability, and the safety of the system on public roads. This thesis provides experimental validation of the string stability of the Assume-Guarantee approach. This approach suggests that each agent models the interactions with neighbors as bounded disturbances while simultaneously self-imposing symmetric magnitude bounds. Two main controllers were tested in an indoor lab set-up: decentralized platooning and decentralized cooperative adaptive cruise controllers. First, we tested three versions of the platooning controller whose objective is to maintain a constant spacing. They differ in the assumptions and guarantees. We observed a robust performance with relaxed bounds and some violations as the bounds become tighter and tighter. Second, we modified and transformed the platoon model into cooperative adaptive cruise control (CACC). Unlike the platoon controller, the cooperative adaptive cruise controller keeps the time gap constant. Two experiments were conducted at different velocities to evaluate the limitation of the controller. The results show a stable and smooth performance.

Indiana University-Purdue University Indianapolis (IUPUI) / Autonomous vehicles currently dominate the automobile field for their impact on humanity and society. Connected and Automated Vehicles (CAV’s) are vehicles that use different communication technologies to communicate with other vehicles, infrastructure, the cloud, etc. With the information received from the sensors present, the vehicles analyze and take necessary steps for smooth, collision-free driving. This the sis talks about the cruise control system along with the intersection collision avoidance system based on Petri net models. It consists of two internal controllers for velocity and distance control, respectively, and three external ones for collision avoidance. Fault-tolerant redundant controllers are designed to keep these three controllers in check. The model is built using a PN toolbox and tested for various scenarios. The model is also validated, and its distinct properties are analyzed.

Preliminary plots are required when beginning a cruise for a timber sale in order to get an idea of how much variation in volume exists within the sale area. This variation is known as the coefficient of variation (CV) and is subsequently used to estimate the number of plots needed to implement the cruise to a desired level of accuracy (allowable error). By looking at a large number of sale inventories and finding similarities among key attributes (trees per acre, diameter at breast height and an estimate of variance), two models were derived based on simple stand observations to aid field personnel in determining a more accurate estimate of the CV. Furthermore, the models estimate the number of 1/10 acre plots needed to sample a stand to within a ± 10% allowable error at the 90% confidence level for total tonnage.

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An investigation of the flow field during eject of a cruise missile from the launch tube was undertaken using a "cold" flow simulation. A facility was developed whereby various design changes in the missile ejection apparatus, denoted the vertical support assembly, could be quickly and easily assessed in terms of the relative effects on the flow field. Flow visualization techniques using fluorescent dye allowed for documentation of flow patterns in the baseline configuration, such as backflow, jetting, and recirculation regions, as well as for the location of several potential hot spots. The mixing of the fuel-rich gas generator effulent and the air in the launch tube was assessed by thermocouple measurements; warm water was used to simulate the exhaust while ambient water represented the air initially contained in the launch tube. The results have shown that air is inefficiently mixed in large portions of the vertical support assembly volume. However, strong flameholding zones are established in the region vacated by the accelerating missile, where it is believed that secondary combustion could occur. The flow field characterization has shown that considerable improvements to system performance should be possible through geometrical changes to promote more efficient mixing. / M.S.

Yes / The purpose of this study is to investigate what type of Facebook posts help cruise lines build bridging and bonding social capital. The study applies the Chi-Square Automatic Interaction Detection (CHAID) method to identify which types of posts establish bridging and bonding social capital. The analysis is conducted on an international cruise line’s official Facebook posts posted between 1 January 2018 and 1 January 2020 before the Covid-19 pandemic. The results highlight that media type, embedding passenger motivation, and a ship image help establish both bridging and bonding social capital, while content type helps establish bridging social capital. The paper is original because it helps understand how cruise lines can improve bonding and bridging social capital via social media. The paper also enhances understanding of social capital theory in the travel industry by investigating the relationship between Facebook post types and social capital in cruise shipping.

Une trace est une suite d’empreintes, laissées par le passage d’un être ou d’un objet – c’est donc avant tout l’indice d’un chemin parcouru. C’est à ce déplacement dans le temps et dans l’espace qu’invitent mes travaux de recherche dont l’objectif est de suivre Edith Wharton « à la trace ». La trace, c’est d’abord, pour ce qu’elle nous apprend sur le voyageur et son rapport au monde, cette croisière en Méditerranée qu’elle entreprend en 1888 à bord du Vanadis. C’est également l’empreinte qui subsiste de cette expérience du voyage : un manuscrit dactylographié qui retrace le périple et rend compte du rapport particulier d’Edith Wharton à l’écriture.La trace – ce qu’on suit (« suivre à la trace ») – renvoie donc à une double activité : d’une part au voyage lui-même, d’autre part, à l’exploration de toutes les pistes que j’ai cru bon d’ouvrir à partir du document originel : sur la vie et l’œuvre d’Edith Wharton, sur son environnement socio-culturel et sur le genre de la littérature de voyage – toute une série d’empreintes, donc de signes conduisant à de nombreux signifiés. La question demeure toujours, en dernier ressort, de savoir si les signifiés que croit avoir découvert le chercheur sont bien ceux de l’écrivain. / A trace is both a material imprint and a trail or series of imprints, marking the passage of a being or an object in transit; it can therefore be understood as the material evidence of a path that has been pursued. In the particular context of this research, the term trace refers first and foremost to the record of a sea voyage. This unpublished journal, kept by Edith Wharton, gives an account of the various stages of the Mediterranean cruise she made in the yacht, the Vanadis, in the spring of 1888.This long book is of particular interest, insofar as it, not only gives a fascinating account of the response of a young nineteenth-century cultivated American to the different cultures discovered in the course of a voyage leading her from North Africa to the Greek Islands and the shores of the Adriatic, but also provides valuable insight into the early responses of an artist in the making.The term “trace” therefore refers to both these aspects: first the voyage itself, the places visited, their physical features and historical significance; secondly the traces left by the visitor who embarked on this adventure at a turning point in her life. The sentiment that the future artist is poised at the crossroads of her existence, leads the researcher – in an attempt to leave as few stones as possible unturned – on a trail leading back to her past and forward to her future. This investigation would not be complete without a survey of travel literature, as the particular genre Edith Wharton has chosen as her means of expression. All these traces unite to form a series of “signs” (in the Saussurian sense of the word), which the researcher endeavours to interpret in the hopes of understanding what is “signified” on a deeper level.

The cruise sector, despite being a niche in the tourism industry, stands out as one of the fastest-growing segments. The ‘cruisescape’ refers to the physical environment and atmosphere on a cruise ship, including elements such as interior design, services and interactions, all of which impact the sensory experience of cruise tourists. Theming plays a significant role in shaping and enhancing the tourist experience within this cruisescape. It has become a central aspect of tourism and consumption, significantly influencing experiences and choices in these domains. This study investigated the impact of theming on cruise ship experiences through deductive reasoning, employing a qualitative approach.The research involved conducting eleven semi-structured interviews with cruise ship tourists. Following a thematic analysis, the study aimed at uncovering patterns and themes within the collected data. Four distinct themes were found within the context of themed experiences on cruise ships: (1) Ever-changing Environment, (2) Perception of Authenticity, (3) Interaction and (4) Multisensory Stimulation. From these four identified themes, three fundamental contributors emerged that significantly influence the cruise ship experience- the themed cruisescape, guests themselves and onboard crew members. The findings offer valuable insights into how the cruisescape, guests, and onboard crew members contribute to shaping the experiences of cruise tourists. Despite the commonalities found in the study’s outcomes, it is crucial to acknowledge the limitation of not generalizing the results to the entire population. Therefore, further investigations will contribute to a better understanding of themed cruisescapes and tourist experiences, allowing for a judgment about whether the results obtained from the research can be generalized or considered valid for a specific set of circumstances.

Carnival, Royal Caribbean, and Norwegian—the most profitable cruise lines today—emerged between the late 1960s and early 1970s, as the elitist leisure ocean travel industry attempted to recover from economic downturn. These mass-market lines targeted an American middle class that increasingly had the desire and financial means to travel. They secured much of this untapped market by creating packaged vacations that responded to the needs and tastes of a middle-class clientele. Drawing on cruise advertisements, newspaper articles, ephemera, industry documents, travel writing, and memorabilia books, this dissertation analyzes how these three companies used cultural and geographic referents to produce cruise vacations, responding to an increased consumer interest in cultural sampling as an accruement of economic globalization. Findings suggest that cruise ships offered their owners a space to arrange simulated interactions with global cultures—a practice that soon extended to Caribbean cruise ports as these companies gained the market power to influence encounters there. This complex collision of global cultures was advanced by a goal to offer passengers opportunities to discover new worlds. However, many of the cultural representations displayed on cruise ships were pastiches—essentializations drawn from popular media forms and based in Eurocentrism. These were meant to be entertaining, not accurate, representations. Nevertheless, as themed environments gained momentum, these cultural forms helped to transform ships into destinations in their own right—a process through which cruise lines produced a captive audience to siphon passenger spending from the Caribbean. At the same time, cruise lines leveraged their mediating power and economic influence to hide from passengers the supposed poverty, crime, and disease at Caribbean ports, and even the mundanities of daily life there, while increasingly installing mechanisms to appropriate spending from those who chose to debark the ship. These processes intensified as the decades advanced. This study thus finds that cultural homogenization did not result in an immediately apparent reduction of difference, because difference was profitable and central to the mass-market cruise industry’s advertising strategies. However, the surface-level cultural heterogeneity that cruises offered was reduced through a homogenizing vision that balanced novelty with passenger comfort, engagement, and convenience in support of corporate profits. The resulting cultural production process was not suggestive of glocalization, but rather a new phenomenon meriting further research.