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Communications of the ACM

121 - 130 of 2,321 for bentley

Efficient traffic crash and snow complaint GIS system

We describe the design and implementation of a traffic crash and snow complaint GIS system developed for the Lincoln Public Works department. We also describe a novel geocoding algorithm that was used to move data from the older Criminal Justice Information System, which is a relational database, to the new GIS system. In addition, we describe the implementation of several indexing algorithms that enable the system to efficiently answer rectangular range queries and queries about the relative locations of moving objects.

Computing technologies for reflective, creative care of people with dementia

Mobile apps manage data on individual residents to help carers deliver more person-centered care.

Fast nearest neighbor retrieval for bregman divergences

We present a data structure enabling efficient nearest neighbor (NN) retrieval for bregman divergences. The family of bregman divergences includes many popular dissimilarity measures including KL-divergence (relative entropy), Mahalanobis distance, and Itakura-Saito divergence. These divergences present a challenge for efficient NN retrieval because they are not, in general, metrics, for which most NN data structures are designed. The data structure introduced in this work shares the same basic structure as the popular metric ball tree, but employs convexity properties of bregman divergences in place of the triangle inequality. Experiments demonstrate speedups over brute-force search of up to several orders of magnitude.

From silhouettes to 3D points to mesh: towards free viewpoint video

This paper presents a system for 3D reconstruction from video sequences acquired in multi-camera environments. In particular, the 3D surfaces of foreground objects in the scene are extracted and represented by polygon meshes. Three stages are concatenated to process multi-view data. First, a foreground segmentation method extracts silhouettes of objects of interest. Then, a 3D reconstruction strategy obtains a cloud of oriented points that lie on the surfaces of the objects of interest in a spatially bounded volume. Finally, a fast meshing algorithm provides a topologically correct interpolation of the surface points that can be used for both visualization and further mesh processing purposes. The quality of the results (computational load) obtained by our system compares favorably against a baseline system built from state-of-the-art techniques for similar processing times (quality of the results).

Practice-based CSCW Research: ECSCW bridging across the Atlantic

Practice-based CSCW research is an orientation towards empirically-grounded research embracing particular methodological approaches with the aim of creating new theory about work, collaboration, and cooperative technologies. While practice-based CSCW research has several strong roots in both North America and Europe: ECSCW and Europe remain central to this tradition. In this panel we will discuss the practice-based research approach asking questions such as: What is the nature of Practice-based Computer Supported Cooperative Work research? How is it different from other CSCW research approaches? What is the relationship between these traditions in terms of conceptual approaches, methodologies and open questions for future research? This panel will discuss openly the diversity and commonalities between different CSCW traditions - and argue that practice-based CSCW research is not something that happens only at ECSCW. ECSCW is not a geographical boundary for a certain type of research - but rather a place for a specific research tradition and approach with links to many academic places in the world.

TEXNH trees: a new course in data structures

The TEXNH method is an approach to undergraduate computer science education that is based on cognitive constructivisim, in the sense of Piaget, and which invokes several course design directives that include re-combining art and science, problem-based learning, problem selection from the visual problem domain, and cognitive apprenticeship. The paper describes a new TEXNH course in data structures. It includes a full comparative assessment of the realized improvement in student problem solving capability and, for the first time, cognitive authenticity in problem selection, in that the course problem is a variation on a very recent research result.

Software variability: the design space of configuration languages

Software variability is a major driver in software development. In order to satisfy the increased variability requirements in today's software, several technical and non-technical variability mechanisms have been proposed. In this paper, we contribute with a language-specific perspective on how to manage variability. We explain our view on the concept of configuration languages, which are languages that offer structural and behavioral program configurations through specifically tailored expressions. We present seven design dimensions of configuration languages that determine how the variability model is defined and how a program's artifacts are represented and modified. To show the applicability of the design dimensions for explaining existing configuration languages, we analyze the Linux Kernel configuration language.

The game of funding: modelling peer review for research grants

Procedures of peer review for research proposals often contain an implicit conflict of interest, where academics may take the role of reviewer or submitter, and thus have the capability to affect the success or failure of each other to obtain some portion of limited funds. This work models a peer review procedure for funding from the perspective of evolutionary game theory. An analysis is performed to investigate the long-term submission and review strategies evolved by the modeled academics as they attempt to maximize their funding. Repercussions of the findings are discussed.

Interactive paper devices: end-user design & fabrication

We describe a family of interactive devices made from paper and simple electronics: Paper Robots, Paper Speakers and Paper Lamps. We developed construction techniques for these paper devices and the Paper Factory software with which novice users can create and build their own designs. The process and materials support DIY design and could be used with low-cost production and shipment from an external service.

Improving particle swarm optimization with differentially perturbed velocity

This paper introduces a novel scheme of improving the performance of particle swarm optimization (PSO) by a vector differential operator borrowed from differential evolution (DE). Performance comparisons of the proposed method are provided against (a) the original DE, (b) the canonical PSO, and (c) three recent, high-performance PSO-variants. The new algorithm is shown to be statistically significantly better on a seven-function test suite for the following performance measures: solution quality, time to find the solution, frequency of finding the solution, and scalability.