Browsing by Subject "Mobility"

Now showing 1 - 20 of 25
  • Thumbnail Image
    Item
    Beyond Accessibility and Behavioral Outcomes: Re-conceptualizing Equity in Transportation through the Capabilities Approach
    (2020-09) Wang, Jueyu
    In the past decades, transportation equity has attracted increasing attention from transportation researchers and policymakers. Nonetheless, there is a lack of theoretical understanding of transportation equity. The dissertation engages the Capability Approach of Sen and Nussbaum as a theory of justice and well-being to conceptualize transportation equity as the process of the production of the equality of mobility capabilities, the substantial freedom people have to travel. Specifically, I propose an equity evaluative framework of five evaluation domains, including 1) Access to basic resources, services, and activities sites; 2) The freedom of physical movement around places; 3) Opportunities for active travel (walking and bicycling); 4) Opportunities to conduct safe and psychologically satisfied trips; 5) Access to political engagement activities. The dissertation also applies the CA framework to two different empirical contexts. One assesses the inequalities of mobility outcomes and capabilities of traveling within low-car ownership households. The results reveal that low-car ownership people of different socio-economic groups achieve different mobility outcomes under the different levels of mobility capabilities. The analysis suggests the joint evaluation of mobility capability and outcomes in informing transportation inequity and disadvantage. The second examines the inequalities of travel mood among different socio-demographic groups and how mobility capabilities, measured as modal options and access destination opportunities, interact with travel mood. The results reveal the significant impacts of mobility capabilities on travel mood and the moderation effects of mobility capabilities on the relationship between mode and mood. The findings highlight the importance of explicit consideration of mobility capabilities– in policy debates and planning initiatives. The concluding chapter contextualizes these findings within the transportation literature and proposes several take-away for policy and future research directions.
  • Thumbnail Image
    Item
    Beyond geometries of activity spaces: A holistic study of daily travel patterns, individual characteristics, and perceived wellbeing in Helsinki metropolitan area
    (Journal of Transport and Land Use, 2019) Hasanzadeh, Kamyar; Czepkiewicz, Michal; Heinonen, Jukka; Kyttä, Marketta; Ala-Mantila, Sanna; Ottelin, Juudit
    Activity space (AS) is a measure of spatial behavior used to summarize the mobility behavior of individuals. Current studies often highlight the fact that AS is highly complex and multidimensional in character. Therefore, the need for more holistic approaches providing more comprehensive descriptions of mobility patterns is evident. This article assesses the activity spaces of young adults aged 25–40 living in the Helsinki metropolitan area using a dataset collected with an online map survey. Using a wide range of measurements covering different aspects of AS, we identified seven components that define activity spaces, namely size, intensity of activities, volume of trips, exteriority, polycentricity, elongation, and destination specialization. We then used the components together with travel mode use to identify a typology of daily mobility patterns. The results show that individuals with different types of AS differ significantly in their socio-demographic characteristics, such as age, gender, employment, household characteristics, and residential neighborhood. Furthermore, the study reveals interesting associations between AS characteristics and different aspects of wellbeing. Overall, the results highlight the importance of multidimensional and comprehensive approaches to understanding daily mobility of urban residents.
  • Thumbnail Image
    Item
    Communities on the Move: Practice and Mobility in the late Eighteenth-Century Western Great Lakes Fur Trade
    (2016-08) Allard, Amélie
    This dissertation elaborates a framework for interpreting the archaeological site of Réaume’s Leaf River Post, a late eighteenth-century fur trading post in Central Minnesota. It examines the construction of social relationships and community in relation to place both within the site and across the broader fur trade landscape of the Western Great Lakes. I consider the ways in which Euro-Canadian fur traders made sense of an unfamiliar landscape by producing a familiar social space (or places) while on the move. Firstly, they did so through daily practices that are recoverable archaeologically, such as foodways and architecture. Together, such activities served to produce a particular lived space, which also created a stage for the enactment of shared practices. I argue that the transmission of practical knowledge from old timers to newcomers, or sometimes from Native people to traders, worked to create a unique community of practice that revolved around fur trading. Given the mobility associated with this lifestyle, I further argue that mobility not only impacted the materiality of the posts in a particular way, but was in fact part of those shared practices that helped foster a sense of ‘groupness’. This community formation process involves operations of both differentiation and inclusion, which often worked simultaneously and along different layers of identity (social status, ethnicity, experience, etc.). Secondly, place-making and community formation processes also work at the power-laden level of the imagination, representation and discourse, which produce the ‘conceived space’. Here I use for evidence a number of journals and memoirs written by fur traders who operated in our region of interest in the late eighteenth century or the turn of the nineteenth century. These narratives offer valuable insight into the ways in which traders created a particular geographic imaginary through their movement across, and engagement with, the landscape and the people inhabiting it. They turned the unfamiliar landscape into familiar places through stories, food procurement strategies, place-names, mapmaking and references to ‘home.’ The overall objective is to demonstrate how tensions emerged between colonial ideals of sedentary life and the need and desire for mobility, and that the practices and imaginaries of the fur traders in fact embodied these tensions. When considering these issues, Réaume’s Leaf River Post reflects this ambivalence.
  • Thumbnail Image
    Item
    Creating scalable, efficient and namespace independent routing framework for future networks.
    (2011-06) Jain, Sourabh
    In this thesis we propose VIRO -- a novel and paradigm-shifting approach to network routing and forwarding that is not only highly scalable and robust, but also is namespace- independent. VIRO provides several advantages over existing network routing architectures, including: i) VIRO directly and simultaneously addresses the challenges faced by IP networks as well as those associated with the traditional layer-2 technologies such as Ethernet -- while retaining its "plug-&-play" feature. ii) VIRO provides a uniform convergence layer that inte- grates and unifies routing and forwarding performed by the traditional layer-2 (data link layer) and layer-3 (network layer), as prescribed by the conventional local-area/wide-area network di- chotomy and layered architecture. iii) Perhaps more importantly, VIRO decouples routing from addressing, and thus is namespace-independent. Hence VIRO allows new (global or local) ad- dressing and naming schemes (e.g., HIP or flat-id namespace) to be introduced into networks without the need to modify core router/switch functions, and can easily and flexibly support inter-operability between existing and new addressing schemes/namespaces. In the second part of this thesis, we present Virtual Ethernet Id Layer, in short VEIL, a practical realization of VIRO routing protocol to create a large-scale Ethernet networks. VEIL is aimed at simplifying the management of large-scale enterprise networks by requiring minimal manual configuration overheads. It makes it tremendously easy to plug-in a new routing-node or a host-device in the network without requiring any manual configuration. It builds on top of a highly scalable and robust routing substrate provided by VIRO, and supports many advanced features such as seamless mobility support, built-in multi-path routing and fast-failure re-routing in case of link/node failures without requiring any specialized topologies. To demonstrate the feasibility of VEIL, we have built a prototype of VEIL, called veil-click, using Click Modular Router framework, which can be co-deployed with existing Ethernet switches, and does not require any changes to host-devices connecting to the network.
  • Thumbnail Image
    Item
    Designing an Autonomous Service to Cover Transit’s Last Mile in Low-Density Areas
    (Minnesota Department of Transportation, 2024-03) Khani, Alireza; Aalipour, Ali; Kumar, Pramesh
    Public transportation provides a safe, convenient, affordable, and environmentally friendly mobility service. However, due to its fixed routes and limited network coverage, it is sometimes difficult or impossible for passengers to walk from a transit stop to their destination. This inaccessibility problem is also known as the "transit last-mile connectivity problem." Such a lack of connectivity forces travelers to drive, thereby increasing vehicle miles traveled (VMT) on roads. The autonomous mobility-on-demand (AMoD) service, with characteristics such as quick fleet repositioning and demand responsiveness, as well as lower operational cost due to the elimination of operators' wages, has the potential to provide last-mile coverage where fixed-route transit can only provide limited service. This study presents research on designing an AMoD service to solve the transit last-mile problem in Greater Minnesota. After selection of the Miller Hill Mall (MMH) area in Duluth, MN, as the case study site, analysis on local transit services and demand data show that passengers may have to spend significant time walking and cross multiple streets to access stores from transit stops. To address this issue, an AMoD system for last-mile service was designed and integrated with the fixed route transit service. Novel mathematical models and AMoD control algorithms were developed, and simulation experiments were conducted for evaluation of the AMoD service. Simulation results showed that the AMoD service can improve transit quality of service and attract more riders to use transit to the MHM area, and therefore reduce the VMT in the region. These findings were consistent with the literature in that mode choice and first-/last-mile access were highly interdependent and AMoD can improve transit quality of service and reduce VMT. Research on riders' perception of AMoD service and field testing of the AMoD system using the developed models and algorithms are recommended to help agencies prepare for application of AMoD system in the region.
  • Thumbnail Image
    Item
    Divided Together: Traffic and Democratic Life in Bogotá
    (2017-06) Cesafsky, Laura
    The dissertation is based on 12 months of mixed-methods, qualitative research into the traffic problem in Bogotá, Colombia, and the ways that citizens and the local government have responded to it. It proposes an alternative—and more specifically, a philosophically pragmatic—reading of urban democracy that highlights different aspects of the ‘democratic question’ than do the political theories typically forwarded in critical urban geography: liberal and radical democratic theory. The dissertation argues that the ‘failure’ of political institutions to remedy traffic in Bogotá has left the problem to linger and nurture democratic life in the form of collaborative and contestatory public practice. Traffic’s hyper-presence as an engulfing, ‘lived’ environmental situation means that it is readily available to emergent subjects, publics and counter-publics as a living laboratory in which possibilities for engagement and activism are sustained. Moreover, because the mobility problem is an inescapable everyday reality even for elites, it forces Bogotanos into an antagonistic political situation that makes them grapple productively with their troubled togetherness. Although the ability to influence the mobility situation is by no means equal, I further argue that there is a notably accessible quality to traffic: it is an ‘issue’ that Bogotanos from all classes literally walk out into everyday and ‘make their voices heard’ in, in the sense that they can transform the common condition through deliberate action—and often to the frustration of elites who are trying to manage behavior in traffic in the service of their own interests. These arguments are inspired by the work of the American pragmatist John Dewey (1859-1952), the dissertation’s central philosophical interlocutor. Political democracy, for Dewey, is an inventive practice of taking care of the serious trouble in which strangers who do not share a way of life find themselves collectively implicated.
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    Gender Mainstreaming in City Comprehensive Plans, A Transportation Focus
    (2020-04-16) McDonnell, Ania
    Gender mainstreaming is an effective tool to shape policies and planning in order to equally benefit all genders. This paper addresses gender mainstreaming practices with transportation policies, specifically with city comprehensive plans. Transportation is necessary for individual mobility, access, and economic engagement with society. Due to the economic disparities among groups of people, low-income people and women are often faced with different spatial and time mobility. Transportation policy is driving the planning process directly on the local level, through city comprehensive plans, specifically in the transportation section. City comprehensive plans are a broad and general document that set the vision for the city planners and policy makers for the next 20 years. This paper analyzes four city comprehensive plants transportation section alongside existing gender disparities in transportation to address whether the plans are serving the needs of all people and the existing disparities in the transportation system. Gender and transportation are overlooked in the present because there are no measures, guidance, or participation of users in the planning of the document or the systems in place. This paper goes beyond just quantifying gender and gender disparities, by utilizing a mixed-method approach to understand the needs to create a more equitable and inclusive system.
  • Thumbnail Image
    Item
    Individual differences in adolescent and young adult daily mobility patterns and their relationships to big five personality traits: a behavioral genetic analysis.
    (2022-05) Alexander, Jordan
    Youth behavior changes and their relationships to personality have generally been investigated using self-report studies, which are subject to reporting biases and confounding variables. Supplementing these with objective measures, like GPS location data, and twin-based research designs, which help control for confounding genetic and environmental influences, may allow for more rigorous, causally informative research on adolescent behavior patterns. To investigate this possibility, this study aimed to (1) investigate whether behavior changes during the transition from adolescence to emerging adulthood are evident in changing mobility patterns, (2) estimate the influence of adolescent personality on mobility patterns, and (3) estimate genetic and environmental influences on mobility, personality, and the relationship between them. Twins aged Fourteen to twenty-two (N=709, 55% female) provided a baseline personality measure, the Big Five Inventory, and multiple years of smartphone GPS data from June 2016 - December 2019. Mobility, as measured by daily locations visited and distance travelled, was found via mixed effects models to increase during adolescence before declining slightly in emerging adulthood. Mobility was positively associated with Extraversion and Conscientiousness (r of 0.17 ̶ 0.25, r of 0.10 ̶ 0.16) and negatively with Openness (r of -0.11 ̶ -0.13). ACE models found large genetic (A = 0.56 ̶ 0.81) and small-moderate environmental (C of 0.12 ̶ 0.28, E of 0.07 ̶ 0.15) influences on mobility. A and E influences were highly shared across mobility measures (rg = 0.70, re= 0.58). Associations between mobility and personality were partially explained by mutual genetic influences (rg of -0.27 ̶ 0.53). Results show that as autonomy increases during adolescence and emerging adulthood, we see corresponding increases in youth mobility. Furthermore, the heritability of mobility patterns and their relationship to personality demonstrate that mobility patterns are informative, psychologically meaningful behaviors worthy of continued interest in psychology.
  • Thumbnail Image
    Item
    Indoor Spatial Updating with Impaired Vision-Human Performance Data for 32 Normally Sighted Subjects, 16 Low Vision Subjects and 16 Blind Subjects
    (2016-09-21) Legge, Gordon E; Granquist, Christina; Baek, Yihwa; Gage, Rachel; legge@umn.edu; Legge, Gordon E
    Spatial updating is the ability to keep track of position and orientation while moving through an environment. We asked how normally sighted and visually impaired subjects compare in spatial updating and in estimating room dimensions. Groups of 32 normally sighted, 16 low vision and 16 blind subjects estimated the dimensions of six rectangular rooms. Updating was assessed by guiding the subjects along three-segment paths in the rooms. At the end of each path, they estimated the distance and direction to the starting location, and to a designated target (a bean bag dropped at the first segment of their path). Spatial updating was tested in five conditions ranging from free viewing to full auditory and visual deprivation (see documentation for details). The normal and low-vision groups did not differ in their accuracy for judging room dimensions. Correlations between estimated size and physical size were high. Accuracy of low-vision performance was not correlated with acuity, contrast sensitivity or field status. Accuracy was lower for the blind subjects. The three groups were very similar in spatial-updating performance, and exhibited only weak dependence on the nature of the viewing conditions. Conclusions. People with a wide range of low-vision conditions are able to judge room dimensions as accurately as people with normal vision. Blind subjects have difficulty in judging the dimensions of quiet rooms, but some information is available from echolocation. Vision status has little impact on performance in simple spatial updating; Proprioceptive and vestibular cues are sufficient.
  • Thumbnail Image
    Item
    International mobility of undergraduate and Graduate Students in Science, Technology, Engineering, and Mathematics: push and pull factors
    (2013-12) Chien, Chiao-Ling
    This study examines factors that contribute to the cross-border movement of international students in science, technology, engineering, and mathematics (STEM) fields. It analyzes characteristics of host countries (pull factors) associated with international students' arrival for education in STEM fields, as well as characteristics of home countries (push factors) related to STEM student's departure for study abroad.The study applies trend analyses and random- and fixed-effects estimations to data from multiple national and international sources. The findings show that a) international STEM students are increasingly concentrated in countries where English is used for instruction and in countries with advanced technological capabilities; b) industrialized countries that have lower enrollments of their own students in STEM programs or aging populations tend to enroll more international STEM students; c) countries that are neither advanced nor substantially lagging in technological capability send more students abroad to pursue STEM education; and d) STEM students migrate more from countries that already have high emigration rates of highly educated citizens.The findings have implications for higher education policies and practices. Key issues include the following: technologically marginalized countries' low STEM enrollment, which may contribute to a widening disparity in technological capability between countries; the migration of STEM students, which suggests that countries should address possible negative effects of the loss of highly skilled citizens; and the increasing use of English as the language of science, which suggests a tendency toward more English-based instruction in non-English speaking countries.
  • Thumbnail Image
    Item
    Life events, poverty, and car ownership in the United States: A mobility biography approach
    (Journal of Transport and Land Use, 2019) Klein, Nicholas J.; Smart, Michael J.
    What causes families to buy or give up a car in the U.S.? Following the mobility biography approach, we use a nationally representative panel data set, the Panel Study of Income Dynamics (PSID), to examine the role of life events and changes in the built environment and compare the effect that these events have on changes in car ownership. We find that coupling, graduating from college, and the birth or adoption of a child all are associated with increases in car ownership, while breaking up is associated with decreases in car ownership. Moving to or away from transit-rich, dense, walkable neighborhoods matters but only when one moves to a very different type of neighborhood. We also find that life events have a stronger association with gaining a car for non-poor families than for families in poverty. Life events are windows of opportunity when families reevaluate their travel patterns. Interventions at these critical junctures could be an expedient way to decrease car ownership and its attendant problems, especially when combined with improving alternatives to the automobile.
  • Thumbnail Image
    Item
    Life-Space Mobility and Healthcare Costs and Utilization in Older Men
    (2024) Sheets, Kerry
    Objectives: To determine the association of life-space score with subsequent healthcare costs and utilization.Design: Prospective cohort study (Osteoporotic Fracture in Men [MrOS]). Setting: Six US sites. Participants: A total of 1,555 community-dwelling men (mean age 79.3 years; 91.5% white, non-Hispanic) participating in the MrOS Year 7 (Y7) examination linked with their Medicare claims data. Measurements: Life-space during the past month was assessed as 0 (daily restriction to one’s bedroom) to 120 (daily trips outside one’s town without assistance) and categorized (0-40, 41-60, 61-80, 81-100, 101-120). Total annualized direct healthcare costs and utilization were ascertained during 36 months following the Y7 examination. Results: Mean total annualized costs (2020 U.S. dollars) steadily increased across category of life-space score, from $7,954 (standard deviation [SD] 16,576) among men with life-space scores of 101-120 to $26,430 (SD 28,433) among men with life-space scores of 0-40 (p <0.001). After adjustment for demographics, men with a life-space score of 0-40 vs. men with a life-space score of 101-120 had greater mean total costs (cost ratio [CR] = 2.52; 95% confidence interval [CI] = 1.84-3.45) and greater risk of subsequent hospitalization (odds ratio [OR] 4.72, 95%CI 2.61-8.53) and skilled nursing facility (SNF) stay (OR 7.32, 95%CI 3.65-14.66). Simultaneous consideration of demographics, medical factors, self-reported health and function, and the frailty phenotype substantially attenuated the association of low life-space with total healthcare costs (CR for 0-40 vs. 101-120 1.29; 95%CI 0.91-1.84) and hospitalization (OR 1.76, 95%CI 0.89-3.51); the association of life-space with SNF stay remained significant (OR 2.86, 95%CI 1.26-6.49). Conclusion: Our results highlight the importance of function and mobility in predicting future healthcare costs and suggest the simple and convenient life-space score may in part capture risks from major geriatric domains and improve identification of older, community-dwelling adults likely to require costly care.
  • Thumbnail Image
    Item
    Locomotion of serial multiply-actuated tumbling robots.
    (2011-06) Hemes, Brett Robert
    Mobile robots that are able to move about and effectively negotiate their environment are attractive for a wide variety of applications. Such applications include surveillance, inspection, and mobile sensing where robots often present cost-effective alternatives to human labor. Other applications include those that are potentially hazardous to humans; examples of these include search and rescue, monitoring and maintenance of toxic environments, and planetary exploration. A vast majority of research into mobile robots has been limited to structured environments such as research labs, indoor office environments, industrial settings, maintained roads, etc. As the number of mobile robot applications grows, so does the need for such systems to be able to operate in unstructured (general) environments. Such environments often exhibit a wide variety of terrain including uneven surfaces and significant terrain irregularities. In some cases hazardous areas can be tactically avoided with careful path planning, but in general this is not always possible and obstacles must be negotiated directly. For these applications it is imperative that the robot exhibits a sufficient level of mobility to be able to perform required tasks. In addition to mobility requirements, many mobile robot applications are further constrained by limitations on physical size and/or cost. It is often the case that small (inexpensive) robots are preferable if not required. In general, however, it is the case that miniature mobile robots sacrifice mobility in exchange for their small size. Additionally, the increased design complexity of miniature systems often increases both design and manufacturing cost. In this thesis we present a relatively new and unexplored form of robotic locomotion called tumbling which addresses many of the aforementioned existing limitations of miniature mobile robots; the thesis is comprised of three main parts. In the first, tumbling and tumbling robots are defined and discussed in detail as well as other useful notation. Additionally, we present a classification of tumbling robots along with a catalog of existing designs to establish the state of the art. This treatment marks the first of its kind and establishes the first formal definitions with respect to tumbling locomotion for mobile robots. In the second, we examine terrainability of the class of serial multiply actuated tumbling robots by looking at the underlying principles of tumbling interactions with several idealized obstacles. Specifically, we derive configuration equations that relate terrainability to the parameters of an idealized tumbling robot. The results are supported through experimentation using the Adelopod, a physical tumbling robot developed as part of this thesis, over a variety of repeatable terrains. Finally, we conclude by examining the maneuverability for the class of serial multiply actuated tumbling robots and begin to address motion planning for such devices. We present results of several planning algorithms as well as a method for deriving useful distance metrics for significant planning speedup and increased path quality. Results of applying such metrics are presented.
  • Thumbnail Image
    Item
    "Meine kühnsten Wünsche und Ideen": women, space, place, and mobility in late eighteenth- and nineteenth-century Germany
    (2014-04) Shepela, Anja Schoenberg
    This dissertation is an investigation of bourgeois women educators' complex relationships with space and place in late eighteenth- and nineteenth-century Germany. These relationships were greatly influenced by the limited mobility and the restricted access to space that bourgeois women faced within the patriarchal order. At the same time, the very success of these women's professional aspirations hinged upon the securing of spaces for their pedagogical endeavors. I argue that attention to the politics of space and to women's spatial practices, that is, women's use of space, can give us valuable insights into women's initiatives and women's agency. In my study, I therefore focus on the ways in which female educators, as portrayed in historical and in fictional texts, were able to use (built and imagined) space subversively to pursue their own interests and on the strategies they employed in order to create places in which to carry out and professionalize their work in late eighteenth- and nineteenth-century Germany. My study reveals how resourceful women were in their use of space and in turning that space into a place, and it illuminates how women managed to have agency and take control of their lives at a time when the odds were against them. Furthermore, this study uncovers how female authors were using the themes of mobility and women's spatiality as a vehicle for social criticism and as a subversion of hegemonic gender norms. Thus, I integrate readings of literary and other historical documents in order to reach a better understanding of German women and their situation in the late eighteenth and nineteenth century.
  • Thumbnail Image
    Item
    Mobility Optimization in LaxBa1-xSnO3 Thin Films Deposited via High Pressure Oxygen Sputtering
    (2017-08) Postiglione, William
    BaSnO3 (BSO) is one of the most promising semiconducting oxides currently being explored for use in future electronic applications. BSO possesses a unique combination of high room temperature mobility (even at very high carrier concentrations, >1019 cm-3), wide band gap, and high temperature stability, making it a potentially useful material for myriad applications. Significant challenges remain however in optimizing the properties and processing of epitaxial BSO, a critical step towards industrial applications. In this study we investigate the viability of using high pressure oxygen sputtering to produce high mobility La-doped BSO thin films. In the first part of our investigation we synthesized, using solid state reaction, phase-pure stoichiometric polycrystalline 2% La-doped BaSnO3 for use as a target material in our sputtering system. We verified the experimental bulk lattice constant, 4.117 Å, to be in good agreement with literature values. Next, we set out to optimize the growth conditions for DC sputtering of La doped BaSnO3. We found that mobility for all our films increased monotonically with deposition temperature, suggesting the optimum temperature for deposition is >900°C and implicating a likely improvement in transport properties with post-growth thermal anneal. We then preformed systematic studies aimed at probing the effects of varying thickness and deposition rate to optimize the structural and electronic transport properties in unbuffered BSO films. In this report we demonstrate the ability to grow 2% La BSO thin films with an effective dopant activation of essentially 100%. Our films showed fully relaxed (bulk), out-of-plane lattice parameter values when deposited on LaAlO3, MgO, and (LaAlO3)0.3(Sr2TaAlO6)0.7 substrates, and slightly expanded out-of-plane lattice parameters for films deposited on SrTiO3, GdScO3, and PrScO3 substrates. The surface roughness’s of our films were measured via AFM, and determined to be on the nm scale or better. Specular XRD measurements confirmed highly crystalline films with narrow rocking curve FWHMs on the order of 0.05°. The optimum thickness found to maximize mobility was around 100 nm for films deposited at ~8 Å/min. These films exhibited room temperature mobilities in excess of 50 cm2V-1s 1 at carrier concentrations ~3 x 1020 cm-3 across 4 different substrate materials (LaAlO3, SrTiO3, GdScO3, and PrScO3). Contrary to expectations, our findings showed no dependence of mobility on substrate mismatch, indicating that threading dislocations are either not the dominant scattering source, or that threading dislocation density in the films was constant regardless of the substrate. The highest mobility film achieved in this study, 70 cm2V 1s 1, was measured for a film grown at a considerably slower rate (~2 Å/min) and lower thickness (~380 Å). Said film was deposited on a PrScO3 (110) substrate, the most closely lattice matched substrate commercially available for BSO (–2.2% pseudo-cubic). This film showed a high out-of-plane lattice parameter from X-ray diffraction (aop = 4.158 Å), suggesting a significantly strained film. This result highlights the possibility of sputtering coherent, fully strained, BSO films, far exceeding the theoretical critical thickness for misfit dislocation formation, on closely lattice matched substrates. Overall, this work validates the concept of high pressure oxygen sputtering to produce high mobility La-doped BSO films. The mobility values reported in this thesis are comparable to those found for films deposited via pulsed laser deposition in previous studies, and represent record values for sputter deposited BSO thin films.
  • Thumbnail Image
    Item
    Modelling children’s independent territorial range by discretionary and nondiscretionary trips
    (Journal of Transport and Land Use, 2021) Sharmin, Samia; Kamruzzaman, Md.; Haque, Md. Mazharul
    The decline of children's independent mobility (CIM) is now a global concern. This study aims to identify the determinants of the territorial range (TR) of CIM, i.e., the geographical distance between home and places where children are allowed to wander. TR for both discretionary and nondiscretionary trips is studied based on data collected through a questionnaire survey, travel diary, and mapping of travel routes. The study sample was comprised of 151 children 9-14 years of age from Dhaka, Bangladesh. Built environment (BE) data were collected/derived through walkability audits of children’s walking routes and spatial analyses. Children’s TR was regressed by BE, socio-demographics, and perceptual factors. Three multiple regression models were estimated: overall TR, discretionary TR, and nondiscretionary TR. Results showed that children had a longer TR for nondiscretionary trips (664.14 m) compared to discretionary trips (397.9 m). Discretionary TR was largely explained by angular step-depth, street connectivity and the condition of the walking environment of the taken routes. In contrast, angular step-depth, the presence of commercial and retail land uses and the condition of the walking environment were found to be significant predictors of nondiscretionary TR. Children’s perception of social and physical dangers and their satisfaction with tree coverage in the neighborhood also influenced their TR. The findings can inform measures to be taken to expand TR in the urban environment.
  • Thumbnail Image
    Item
    Pantomeshes: kinematics, synthesis, and applications of closed pantograph-style linkage systems.
    (2010-12) Larson, Blake Timothy
    This research describes the kinematics, analysis, and synthesis of a pantomesh. A pantomesh is a patchwork assembly of pantograph elements (known elsewhere as scissor pairs or duplets) that obey certain mobility requirements. A pantomesh, as described in this thesis, has scissor-like elements connected to one another by spherical joints to allow a wide variety of motions. Previous pantograph-style linkages, such as the Hoberman Sphere, use special geometry restrictions and have elements joined with gussets, thereby limiting the variety of shapes possible. The thesis begins with examining the kinematics of pantomeshes and their constituent parts. First, the kinematics of the individual pantograph elements are detailed for further use. The mobility of a closed pantomesh is ensured by the mobility of its constituent pantopatches, two-wide by two-high sub-assemblies of pantograph elements that must be mobile themselves for the entire pantomesh to be mobile. A new method for mobility of spatial linkages is presented relating the use of polygonal elements. Next, two methods for pantomesh synthesis are presented. A graphical method is presented to use a computer-aided design system to create a mobile pantomesh that meets specified requirements. A computational method for synthesis is also presented, using a numerical optimization method to create pantomeshes to certain specifications. Practical considerations of manufacturing are considered in the discussion of multi-link spherical joints, including past work and new approaches. The new approaches include a compliant multi-link spherical joint and a crossed-tendon system that acts a a spherical joint. Finally, an application is presented: a new linkage which provides radial pressure for the purpose of stabilizing a human breast during cancer-related diagnosis and treatment procedures.
  • Thumbnail Image
    Item
    Planning for Disruption: Connected and Autonomous Vehicles
    (Center for Transportation Studies, University of Minnesota, 2019-09) Burga, Fernando; Fisher, Tom
    The future of transportation is inseparable from the future of work. Over the last century, transportation has focused on moving people and goods, but work in the 21st century has started to change dramatically due to vehicle automation, changing consumer patterns, and the rise of virtual retail. These factors will bring profound changes in transportation, infrastructure, and access to resources in the city, including housing, food, public spaces, and labor opportunities. This research project investigated the implications of the forthcoming changes in transportation, mobility, and the nature of work. It focused on the impact of vehicle automation on jobs access and explored the tensions that arise as new vehicle automation technologies are introduced into the streets of neighborhoods with historically disadvantaged residents.
  • Thumbnail Image
    Item
    Quality of Life: Assessment for Transportation Performance Measures
    (Minnesota Department of Transportation, 2013-01) Schneider, Ingrid E.; Guo, Tian; Schroeder, Sierra
    Quality of life (QOL) is a commonly used term. Defining QOL, however, is an ongoing challenge that experts often take on with minimal input from citizens. This groundbreaking research sought citizen input on what comprised QOL and what role transportation played in it. Further, this research explored in detail the important factors across the breadth of transportation and how the Minnesota Department of Transportation (MnDOT) was performing on these important factors. The research encompassed three phases between 2010 and 2011: (1) an extensive literature review on QOL, (2) 24 focus groups that asked Minnesota’s citizens about their QOL, and (3) a mail questionnaire about what matters in quality of life, transportation and their intersection. Eleven related quality of life factors emerged, including transportation: education, employment and finances, environment, housing, family, friends and neighbors, health, local amenities, recreation and entertainment, safety, spirituality/faith/serenity, and transportation. Within transportation, seven important areas were identified that predicted satisfaction with MnDOT services: access, design, environmental issues, maintenance, mobility, safety and transparency. Results reveal that a) QOL is complex and transportation plays an important and consistent role in it across Minnesota; b) transportation is critical to QOL because it connects us to important destinations in aspects that matter most; and c) Minnesotans can readily identify what matters and how the state is performing within the breadth of transportation services.