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GVU Technical Report Series

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Now showing 1 - 10 of 541
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    SQUINT Fields, Maps, Patterns, and Lattices
    (Georgia Institute of Technology, 2018-07-23) Rossignac, Jarek
    The proposed Steady QUad INTerpolating (SQUINT) map is formulated in terms of a SQUINT Field of Similarities (FoS). It is controlled by four coplanar points. It maps the unit square onto a curved planar quad, R, which has these points as corners. Uniformly spaced, log-spiral isocurves decompose R into tiles that are similar to each other and, hence, each have equal angles at opposite corners. We provide closed-form expressions for computing the representation of the SQUINT map and for evaluating the map and its inverse. We discuss extensions and potential applications to texture maps and field warps and to the design, display, and constant-cost query of procedural models of arbitrarily complex lattices.
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    Permutation Classifier
    (Georgia Institute of Technology, 2018-04-24) Zhou, Xinrui ; Guerra, Concettina ; Rossignac, Jarek ; Rossignac-Milon, Leo
    We consider permutations of a given set of n different symbols. We are given two unordered training sets, T1 and T2, of such permutations that are each assumed to contain examples of permutations of the corresponding type, t1 and t2. Our goal is to train a classifier, C(q), by computing a statistical model from T1 and T2, which, when given a candidate permutation, q, decides whether q is of type t1 or t2. We discuss two versions of this problem. The ranking version focuses on the order of the symbols. Our Separation Average Distance Matrix (SADiM) solution expands on previously proposed ranking aggregation formulations. The grouping version focuses on contiguity of symbols and hierarchical grouping. We propose and compare two solutions: (1) The Population Augmentation Ratio (PAR) solution computes a PQ-tree for each training set and uses a novel measure of distance between these and q that is based on ratios of population counts (i.e., of numbers of permutations explained by specific PQ-trees). (2) The Difference of Positions (DoP) solution is computationally less expensive than PAR and is independent of the absolute population counts. Although DoP does not have the simple statistical grounding of PAR, our experiments show that it is consistently effective.
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    Passive Haptic Learning for Vibrotactile Skin-Reading: Comparison of Teaching Structures
    (Georgia Institute of Technology, 2018) Luzhnica, Granit ; Veas, Eduardo ; Seim, Caitlyn
    This paper investigates the effects of using passive haptic learning to train the skill of reading text from vibrotactile patterns. The vibrotactile method of transmitting messages, skin-reading, is effective at conveying rich information but its active training method requires full user attention, is demanding, time-consuming, and tedious. Passive haptic learning offers the possibility to learn in the background while performing another primary task. We present a study investigating the use of passive haptic learning to train for skin-reading. Additionally, a word-based learning structure is typically used for this passive learning method. We expose trends that suggest this word-based incrimental teaching may not be optimal.
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    RangeFinder: Accelerating ball-interference queries against steady lattices
    (Georgia Institute of Technology, 2018) Kurzeja, Kelsey ; Rossignac, Jarek
    Advances in additive manufacturing techniques are enabling the fabrication of new microstructures and materials. These may often be defined in terms of a set of balls and of beams that each connects two balls. To support application needs, we must support lattices with billions of such elements. To address this problem, we focus on architected and periodic structures in which the connectivity pattern repeats in three directions, and in which the positions and radii of the balls evolve through the structure in a prescribed and steady way that is defined by three similarity transforms. We propose here an algorithm that accelerates the Ball-Interference Query (BIQ), which establishes which elements of the lattice interfere with a query ball Q. Our RangeFinder (RF) solution reduces the asymptotic complexity of BIQs, which, in our tests, reduced the query time by a factor of between 45 and 5500. RF does not use any spatial occupancy data structure and can be trivially parallelized. We demonstrate the effectiveness of RangeFinder through the generation of multi-level lattices that we call Lattice-in-Lattice (LiL).
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    Designing and processing parametric models of steady lattices
    ( 2018) Gupta, Ashish ; Kurzeja, Kelsey ; Rossignac, Jarek ; Allen, George ; Kumar, Pranav Srinivas ; Musuvathy, Suraj
    Our goal is to facilitate the design, analysis, optimization, and additive manufacturing of a specific class of 3D lattices that may comprise an extremely large number of elements. We target curved lattices that exhibit periodicity and uniform geometric gradations in three directions, along possibly curved axes. We represent a lattice by a simple computer program with a carefully selected set of exposed control parameters that may be used to adjust the overall shape of the lattice, its repetition count in each direction, its microstructure, and its gradation. In our Programmed-Lattice Editor (PLE), a typical lattice is represented by a short program of 10 to 50 statements. We propose a simple API and a few rudimentary GUI tools that automate the creation of the corresponding expressions in the program. The overall shape and gradation of the lattice is controlled by three similarity transformations. This deliberate design choice ensures that the gradation in each direction is regular (i.e., mathematically steady), that each cell can be evaluated directly, without iterations, and that integral properties (such as surface area, volume, center of mass and spherical inertia) can be obtained rapidly without having to calculate them for each individual element of the lattice.
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    Designing for Civil Conversations: Lessons Learned from ChangeMyView
    (Georgia Institute of Technology, 2017-12-12) Jhaver, Shagun ; Vora, Pranil ; Bruckman, Amy S.
    Research has shown that people all over the world, and particularly Americans, are divided over many issues – from immigration and gun control to economic and foreign policy. Information bubbles further contribute to these divisions: People prefer to consume content they feel familiar with and see views they agree with. Yet, pluralism and viewpoint diversity are necessary for a well-functioning democracy. In this paper, we explore how we can design interfaces that dial down partisan antipathy and allow users with opposing viewpoints to understand one another. We study ChangeMyView (CMV) subreddit, a community that encourages users to change their opinion by inviting reasoned counterarguments from other members. We use interviews with 15 CMV members to gain insights about the design mechanisms and social norms that allow this community to function well. We also explore how we can replicate such civil interactions between users with different ideologies on other platforms.
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    Perception in Hand-Worn Haptics: Placement, Simultaneous Stimuli, and Vibration Motor Comparisons
    (Georgia Institute of Technology, 2015) Seim, Caitlyn ; Hallam, James ; Raghu, Shashank ; Le, Tri-An ; Bishop, Greg ; Starner, Thad
    Glove-based tactile interfaces are used for augmented reality, rehabilitation, teaching, and consumer electronics control. Yet questions remain regarding perception of tactile stimuli on the hands. In an effort to inform the design of such tactile interfaces, we investigate participants' abilities to sense vibration on the hands. First, we examine the effect of stimulus location on recognition accuracy. Ventral (palm-side) placement on the fingers is critical: accuracy increases with proximity to the palm, linearly, on all fingers. Second, we study perception of multiple simultaneous vibrations on the fingers. Recognition degrades with increasing number of simultaneous tactile stimuli and no subitizing is found. Error is >60-80\% for more than two simultaneous stimuli points. Our third study compares the perception of Eccentric Rotating Mass (ERM) and Linear Resonant Actuator (LRA) vibration motors. Recognition accuracy was less using LRA motors, especially in placements on the palm side of the fingers (-20.3% versus -10.1% for ERM). Correct recognition of chords was also less or comparable using LRA motors, suggesting that the ERM motor is preferable.
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    A Strategy for Addressing Ambiguity in Regulatory Requirements
    (Georgia Institute of Technology, 2015) Massey, Aaron K. ; Rutledge, Richard L. ; Antón, Annie ; Hemmings, Justin D. ; Swire, Peter P.
    Ambiguities in legal texts can make the difference between regulatory compliance and non-compliance in software systems. Ambiguities are prevalent in laws and regulations. Policy analysts who write laws and regulations and software engineers who build software systems that must comply with laws and regulations approach ambiguity differently. In our prior work, we surfaced differences between the approach taken by policy analysts and technologists in identifying and classifying ambiguities in legal texts. Understanding the rationale behind the identification and classification of legal ambiguities is essential to disambiguating them for requirements engineering. Herein, we discuss a case study in which we seek to understand the rationale used to make determinations about ambiguities in legal texts. Our 48 case study participants identified 373 ambiguities, 99.1% of which were classified using our ambiguity taxonomy. The results of our qualitative analysis suggest participants are consistently able to identify words and phrases they believe to be ambiguous, but are unable to express and agree on a consistent rationale defending their classification. This result supports a strategy for addressing ambiguity in regulatory requirements—software engineers are likely to be successful at identifying components of legal texts that then require supplemental expertise to resolve.
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    Defining the Internet of Devices: Privacy and Security Implications
    (Georgia Institute of Technology, 2014-06) Rutledge, Richard L. ; Massey, Aaron K. ; Antón, Annie I. ; Swire, Peter
    What observers have called the Internet of Things (IoT) presents privacy and security challenges for contemporary society. The conceptual model of the IoT evolved rapidly from technologies used to track parts in industrial supply chain management to a diverse set of smart technologies. This rapid evolution has merged several conceptually distinct technologies into a single, difficult-to-define concept. A key difficulty is defining what constitutes a “thing.” The term has been used to refer both to the things sensed, such as a star or the contents of a refrigerator, and to the things that do the sensing (devices). We argue that the Internet of Things is better conceptualized as an Internet of Devices (IoD) because devices, not things, act in a digital form and connect to the Internet. Along with the other requirements of an effective IoD, technologists and policy makers must develop standards, network protocols, identity management solutions, and governance for the IoD to address privacy and security challenges a priori rather than retrofitted after the fact. Privacy and security cannot easily be added to a system that is already deployed and established. In this paper, we define the IoT and the IoD and summarize the independent technologies from which they have evolved. We provide a five-stage general policy framework for evaluating privacy and security concerns in the IoD. Our framework seeks to provide a consistent approach to evaluating privacy and security concerns across all IoD technologies while remaining flexible enough to adapt to new technical developments.
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    Can I Wash It? : The Effect of Washing Conductive Materials Used in Making Textile Based Wearable Electronic Interfaces
    (Georgia Institute of Technology, 2013) Zeagler, Clint ; Gilliland, Scott ; Audy, Stephen ; Starner, Thad
    In this paper we explore the wash-ability of conductive materials commonly use in creating traces and touch sensors in wearable electronic textile systems. We performed a wash test measuring change in resistivity of conductive traces constructed using different combinations of conductive materials after each wash cycle.