Poisson multi-Bernoulli mixture trackers: continuity through random finite sets of trajectories

The Poisson multi-Bernoulli mixture (PMBM) is an unlabelled multi-target distribution for which the prediction and update are closed. It has a Poisson birth process, and new Bernoulli components are generated on each new measurement as a part of the Bayesian measurement update. The PMBM filter is similar to the multiple hypothesis tracker (MHT), but seemingly does not provide explicit continuity between time steps. This paper considers a recently developed formulation of the multi-target tracking problem as a random finite set (RFS) of trajectories, and derives two trajectory RFS filters, called PMBM trackers. The PMBM trackers efficiently estimate the set of trajectories, and share hypothesis structure with the PMBM filter. By showing that the prediction and update in the PMBM filter can be viewed as an efficient method for calculating the time marginals of the RFS of trajectories, continuity in the same sense as MHT is established for the PMBM filter

Mitigation of Motion Sickness Symptoms by Adaptive Perceptual Learning: Implications for Space and Cyber Environments

A phenomenon regarding motion sickness mitigation, documented infrequently in the scientific literature on motion countermeasures, involves pre-exposing individuals to unusual motion, resulting in reduced symptoms on subsequent exposures to similar or even dissimilar motion events. The phenomenon does not seem to have the attention that a drug free and rapidly applied technique deserves in literature reviews of motion mitigation. This phenomenon is designated as Adaptive Perceptual Learning (APL) to highlight the idea that some, as yet unexplained, perceptual learning is involved in pre-adapting individuals to motion sickness. The experience of new motion environments that could greatly benefit humanity, such as space travel and cyberlearning, are hampered by symptoms of motion sickness. These environments would benefit from APL if a milder means to induce motion sickness could lessen the symptoms of another, more severe environment. We conducted a study to test APL using visually induced motion sickness (VIMS). In order to prevent order effects, half the participants in this study received a virtual reality (VR) version of a traditional VIMS first and the other half received a traditional VIMS first. Later, the exposure was reversed. Significant effects were found on a standard motion symptoms questionnaire, supporting the idea of APL. We are testing the idea again in a shortened version of this study to see if a more rapid application can be found. A successful outcome would support soliciting more funding to expand on APL and determine the parameters that would be useful for cyberlearning or space motion sickness

Parks for all: Information on accessibility and associated experiences.

This thesis examines the accuracy of accessibility information for parks and the related experiences of visitors. It explores whether or not there is a gap between the information that is made available to the public and the experiences that are available on the ground. People with mobility impairments encounter barriers to movement. The provision of information on accessibility may assist those with impairments to select recreational opportunities that are compatible with their interests and abilities. Accordingly, the availability and accuracy of information on accessibility is evaluated through comparison with on-site field observations. Four parks of different management types – local, regional, provincial and national – are examined. Promotional information was gathered primarily from brochures and websites. Key informant interviews were conducted and on-site measurements of accessibility were taken. The quantity and accuracy of information on accessibility varied between the parks. Inconsistencies were found between the information on accessibility and the on-site situations. Details on park features like parking, trails, washrooms, visitor centers and campsites lacked volume, specifics and accuracy, and these features are important to individuals with a mobility impairment. Stronger links should be established between the monitoring of accessibility and the timely, accurate provision of accessibility information. There is willingness among park officials to address accessibility issues but financial constraints are widely regarded as being an impediment to action. As such, physical improvements to accessibility are most likely to occur as a part of general maintenance schedules. Nevertheless, regular systematic monitoring and reporting is not expensive and would benefit park management by enabling them to provide more accurate information to the public. The study also suggests that greater engagement with the impaired community could be beneficial to parks, official, and visitors

Managing Accessibility: A Case Study at the University of Waterloo

This study examined how a quality management system, which includes a crowdsourcing application, could improve accessibility. As a result this research captured the interactions a person with impairment has with the built environment they encounter and how those experiences are facilitated. No person should be denied access to quality of life enhancing services based on ability. Currently, however, there is a deficient focus on accessibility. Despite legislative advancements, much of North America’s current infrastructure and facilities predate accessibility law. While standards regulate accessibility, current building codes offer few contemporary methods for improving accessibility beyond basic guidelines. In that regard, a quality management framework could provide attention and incremental improvement to accessibility. This case study analyzed connections between people and accessibility at the University of Waterloo. Qualitative methods allowed meaning to emerge from key informant interviews. Secondary sources revealed how university operations function. Observations provided data that illustrated effective or ineffective accessibility. Investigation was not limited to the physical provision of access. It included an inquiry of the patterns, behaviors, and mechanics of providing accessibility. Naturally, accessibility was not the only field where potential improvements were delayed or precluded because of systems concerns. For good environmental practice, the manufacturing industry’s reaction to environmental concerns led to the increased use of environmental management systems (EMS) that were based on quality management frameworks. ISO-14001 is an extensive EMS focused on improving quality, which manages tangible inputs (legal compliance, auditing, or reporting) to a larger less tangible concept (environmental conservation). Similarly, accessibility could benefit from recurrent managerial improvements that would identify, manage, and report barriers for improvement. The aspects of ISO-14001 can be adapted for improving accessibility. Based on the findings, management systems are not used to provide accessibility on campus. While there are no major barriers to impede a person from their educational pursuits, there are some limitations that affect equal opportunities for people with disabilities. Often the limitations remain unchanged. New construction of facilities affords opportunity for improved access. Existing procedures do not give accessibility the attention needed for regular improvements. A quality-based management system would incorporate the aspects of accessibility to gain incremental refinements. Including the crowdsourcing application would provide valuable feedback to assist the process

Optimal Design and Synthesis of MEA Power System Architectures considering Reliability Specifications

IEEE Aircraft electrification requires novel designs to supply the growing demand for electric power on-board through efficient and reliable production and distribution of electrical energy. Moreover, the aircraft power system will be a key enabler for the integration of future technologies. Pledging to these intentions, we propose a formulation to synthesize a power system architecture that complies with safety specifications following a Platform Based Design methodology that optimizes the main aerospace drivers. Due to the non-linear nature of the design problem, this paper presents reliability based MILP network design formulations for topology synthesis. The novelty of this approach relies in the adoption of network design optimization for MEA power system construction that allows explicit design formulations as MILP problems. This approach will provide an effective way to include safety specifications by introducing reliability and resiliency constraints

Eliminating artificial boundary conditions in time-dependent density functional theory using Fourier contour deformation

We present an efficient method for propagating the time-dependent Kohn-Sham equations in free space, based on the recently introduced Fourier contour deformation (FCD) approach. For potentials which are constant outside a bounded domain, FCD yields a high-order accurate numerical solution of the time-dependent Schrodinger equation directly in free space, without the need for artificial boundary conditions. Of the many existing artificial boundary condition schemes, FCD is most similar to an exact nonlocal transparent boundary condition, but it works directly on Cartesian grids in any dimension, and runs on top of the fast Fourier transform rather than fast algorithms for the application of nonlocal history integral operators. We adapt FCD to time-dependent density functional theory (TDDFT), and describe a simple algorithm to smoothly and automatically truncate long-range Coulomb-like potentials to a time-dependent constant outside of a bounded domain of interest, so that FCD can be used. This approach eliminates errors originating from the use of artificial boundary conditions, leaving only the error of the potential truncation, which is controlled and can be systematically reduced. The method enables accurate simulations of ultrastrong nonlinear electronic processes in molecular complexes in which the inteference between bound and continuum states is of paramount importance. We demonstrate results for many-electron TDDFT calculations of absorption and strong field photoelectron spectra for one and two-dimensional models, and observe a significant reduction in the size of the computational domain required to achieve high quality results, as compared with the popular method of complex absorbing potentials

Multi-Scan Implementation of the Trajectory Poisson Multi-Bernoulli Mixture Filter

The Poisson multi-Bernoulli mixture (PMBM) and the multi-Bernoulli mixture (MBM) are two multitarget distributions for which closed-form filtering recursions exist. The PMBM has a Poisson birth process, whereas the MBM has a multi-Bernoulli birth process. This paper considers a recently developed formulation of the multitarget tracking problem using a random finite set of trajectories, through which the track continuity is explicitly established. A multiscan trajectory PMBM filter and a multiscan trajectory MBM filter, with the ability to correct past data association decisions to improve current decisions, are presented. In addition, a multiscan trajectory MBM01 filter, in which the existence probabilities of all Bernoulli components are either 0 or 1, is presented. This paper proposes an efficient implementation that performs track-oriented N-scan pruning to limit computational complexity, and uses dual decomposition to solve the involved multiframe assignment problem. The performance of the presented multitarget trackers, applied with an efficient fixed-lag smoothing method, is evaluated in a simulation study