Technical Report: Cooperative Multi-Target Localization With Noisy Sensors

This technical report is an extended version of the paper 'Cooperative Multi-Target Localization With Noisy Sensors' accepted to the 2013 IEEE International Conference on Robotics and Automation (ICRA). This paper addresses the task of searching for an unknown number of static targets within a known obstacle map using a team of mobile robots equipped with noisy, limited field-of-view sensors. Such sensors may fail to detect a subset of the visible targets or return false positive detections. These measurement sets are used to localize the targets using the Probability Hypothesis Density, or PHD, filter. Robots communicate with each other on a local peer-to-peer basis and with a server or the cloud via access points, exchanging measurements and poses to update their belief about the targets and plan future actions. The server provides a mechanism to collect and synthesize information from all robots and to share the global, albeit time-delayed, belief state to robots near access points. We design a decentralized control scheme that exploits this communication architecture and the PHD representation of the belief state. Specifically, robots move to maximize mutual information between the target set and measurements, both self-collected and those available by accessing the server, balancing local exploration with sharing knowledge across the team. Furthermore, robots coordinate their actions with other robots exploring the same local region of the environment.Comment: Extended version of paper accepted to 2013 IEEE International Conference on Robotics and Automation (ICRA

Multi-Robot Active Information Gathering Using Random Finite Sets

Many tasks in the modern world involve collecting information, such as infrastructure inspection, security and surveillance, environmental monitoring, and search and rescue. All of these tasks involve searching an environment to detect, localize, and track objects of interest, such as damage to roadways, suspicious packages, plant species, or victims of a natural disaster. In any of these tasks the number of objects of interest is often not known at the onset of exploration. Teams of robots can automate these often dull, dirty, or dangerous tasks to decrease costs and improve speed and safety. This dissertation addresses the problem of automating data collection processes, so that a team of mobile sensor platforms is able to explore an environment to determine the number of objects of interest and their locations. In real-world scenarios, robots may fail to detect objects within the field of view, receive false positive measurements to clutter objects, and be unable to disambiguate true objects. This makes data association, i.e., matching individual measurements to targets, difficult. To account for this, we utilize filtering algorithms based on random finite sets to simultaneously estimate the number of objects and their locations within the environment without the need to explicitly consider data association. Using the resulting estimates they receive, robots choose actions that maximize the mutual information between the set of targets and the binary events of receiving no detections. This effectively hedges against uninformative actions and leads to a closed form equation to compute mutual information, allowing the robot team to plan over a long time horizon. The robots either communicate with a central agent, which performs the estimation and control computations, or act in a decentralized manner. Our extensive hardware and simulated experiments validate the unified estimation and control framework, using robots with a wide variety of mobility and sensing capabilities to showcase the broad applicability of the framework

BLACK WOMEN PURSUING DOCTORATES IN MATHEMATICS EDUCATION: AN EXAMINATION OF STORIES OF THEIR MATHEMATICAL EXPERIENCES

The research shows a lack of representation of Black women in mathematics education. The purpose of this study was to explore Black women’s perspectives on how their mathematical experiences influenced their decisions to pursue a doctoral degree in mathematics education. To address this issue the following research questions were explored: What perspectives do Black women who are in pursuit of a doctorate of philosophy degree in mathematics education have about their mathematical experiences? How have those perspectives of their experiences influenced their pursuit of a doctorate of philosophy in mathematics education? For this study purposeful sampling was used to select seven participants, that classify themselves as Black women and are currently in a doctoral program in mathematics education. Individual and group interviews conducted with the participants were analyzed using a grounded theory approach to gain an understanding of their mathematical experiences as learners with respect to their trajectories in becoming doctoral students in mathematics education. The Black women that participated in this study had positive feelings about their mathematical abilities. This resulted in confident mathematical identities. The mathematical environment included classrooms with supportive teachers, classmates that were mainly Black, and an even split between the genders. Once this environment was challenged a crisis occurred which caused them to lose confidence in themselves. All of the participants began teaching secondary mathematics as a career change from their initial undergraduate degree. Their initial graduate degrees were in conjunction with their decision to pursue a career as a mathematics educator. The decision to pursue a doctoral degree was out of a personal desire to advance academically as well as desire to effect change within their community. The findings of this study support an achievement motivation framework. This research presents an initial understanding of how perspectives of mathematical experiences influence their decision to pursue doctoral degrees in mathematics education

Exploring Changes In Computer Self-Efficacy During Graphics Skills Acquisition

The present action research study involved a participant-researcher and her undergraduate students enrolled in the Course: Visual Arts Computing, at the University of South Carolina from 2012 to 2013. This research examined six sections of the course with an average of 20 students in each section, totaling 120 participants. The overarching Research Question for the present study was: What factors from social cognitive theory (cognitive, environmental, behavior) influenced students’ self-efficacy with computer technology in an undergraduate graphic arts course? To answer this question the participant-researcher administered a pretest and posttest of the computer self-efficacy scale by Compeau and Higgins (1995b). The course focused on learning foundational art and graphic design concepts through projects created with the graphics software, Adobe Photoshop. “Graphic Skills Acquisition” (GSA) which is associated with improved “computer self-efficacy,” was used in this action research study to increase students’ confidence levels with computers and enhance feelings of positivity when interacting with technology in general. The research showed, based on the pretest and posttest scale, GSA has the potential to influence academic student achievement, workplace productivity, and personal computer self-efficiency outside of the course. The factors identified from Bandura’s social cognitive theory were: independent learning (environmental), new and unfamiliar tasks (cognitive), and behavior modeling (behavior)

Enhancing of Teaching and Learning through Constructive Alignment

This article elucidates issues about practical knowledge/deep learning on the current teaching and learning preaching practices in the Department of Practical Theology at the Faculty of Theology of the University of the Free State. The action learning and action research methodology is applied. Growing evidence indicates that there is a disjunction between the level of student competencies and incongruent teaching practices in the Faculty. Failure in the operationalization of both an interdisciplinary and a constructive alignment approach is at the core of surface learning. It appears that former and current students find it difficult to align their studies and to adapt to an unfamiliar, diverse, pluralistic and complex postmodern society. We teach content and assess students on the basis of what they know. The content does not relate to students’ own experiences or the broader issues in society. We are talking about a change that is deeper than surface alterations to the syllabus or to classroom teaching techniques. We are considering a radically different way of framing the ministry of preaching and of viewing the task of those who seek to learn and to teach preaching

Effective thermal conductivity of polycrystalline materials with randomly oriented superlattice grains

A model has been established for the effective thermal conductivity of a bulk polycrystal made of randomly oriented superlattice grains with anisotropic thermal conductivity. The in-plane and cross-plane thermal conductivities of each superlattice grain are combined using an analytical averaging rule that is verified using finite element methods. The superlattice conductivities are calculated using frequency dependent solutions of the Boltzmann transport equation, which capture greater thermal conductivity reductions as compared to the simpler gray medium approximation. The model is applied to a PbTe/Sb_2Te_3 nanobulk material to investigate the effects of period, specularity, and temperature. The calculations show that the effective thermal conductivity of the polycrystal is most sensitive to the in-plane conductivity of each superlattice grain, which is generally four to five times larger than the cross-plane conductivity of a grain. The model is compared to experimental measurements of the same system for periods ranging from 287 to 1590 nm and temperatures from 300 to 500 K. The comparison suggests that the effective specularity increases with increasing annealing temperature and shows that these samples are in a mixed regime where both Umklapp and boundary scattering are important

The healing of life within the HIV and AIDS pandemic: Towards a pedagogical reframing of paradigms concerning dysfunctional civil, health and ecclesial systems

The inability of government, communities and churches to deal with complex HIV and AIDS challenges may foster pathological psychosocial and systemic dysfunctionalities. The reframing of pathological and disempowering pastoral therapeutic and health promotion praxes are sought. The objective was to construct a new pastoral and social therapeutic methodology. It should develop in line with health promotion praxes in strengthening both ecclesial and community health praxes. Reframing agents such as pastoral therapeutic and health praxes, as well as ecclesial and community systems, could ultimately engender a transformative process in transforming pathological HIV and AIDS praxes