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Full-Text Articles in Systems Architecture

Open Source Foundations For Spatial Decision Support Systems, Jochen Albrecht Dec 2018

Open Source Foundations For Spatial Decision Support Systems, Jochen Albrecht

Publications and Research

Spatial Decision Support Systems (SDSS) were a hot topic in the 1990s, when researchers tried to imbue GIS with additional decision support features. Successful practical developments such as HAZUS or CommunityViz have since been built, based on commercial desktop software and without much heed for theory other than what underlies their process models. Others, like UrbanSim, have been completely overhauled twice but without much external scrutiny. Both the practical and the theoretical foundations of decision support systems have developed considerably over the past 20 years. This article presents an overview of these developments and then looks at what corresponding tools …


The Legacy Of Multics And Secure Operating Systems Today, John Schriner Jan 2018

The Legacy Of Multics And Secure Operating Systems Today, John Schriner

Publications and Research

This paper looks to the legacy of Multics from 1963 and its influence on computer security. It discusses kernel-based and virtualization-based containment in projects like SELinux and Qubes, respectively. The paper notes the importance of collaborative and research-driven projects like Qubes and Tor Project.


Geodesic Merging, Konstantinos Georgatos Jan 2017

Geodesic Merging, Konstantinos Georgatos

Publications and Research

We pursue an account of merging through the use of geodesic semantics, the semantics based on the length of the shortest path on a graph. This approach has been fruitful in other areas of belief change such as revision and update. To this end, we introduce three binary merging operators of propositions defined on the graph of their valuations and we characterize them with a finite set of postulates. We also consider a revision operator defined in the extended language of pairs of propositions. This extension allows us to express all merging operators through the set of revision postulates.


Framing The Question, "Who Governs The Internet?", Robert J. Domanski Jan 2015

Framing The Question, "Who Governs The Internet?", Robert J. Domanski

Publications and Research

There remains a widespread perception among both the public and elements of academia that the Internet is “ungovernable”. However, this idea, as well as the notion that the Internet has become some type of cyber-libertarian utopia, is wholly inaccurate. Governments may certainly encounter tremendous difficulty in attempting to regulate the Internet, but numerous types of authority have nevertheless become pervasive. So who, then, governs the Internet? This book will contend that the Internet is, in fact, being governed, that it is being governed by specific and identifiable networks of policy actors, and that an argument can be made as to …


On The Nonsymmetric Longer Queue Model: Joint Distribution, Asymptotic Properties, And Heavy Traffic Limits, Charles Knessl, Haishen Yao Jan 2013

On The Nonsymmetric Longer Queue Model: Joint Distribution, Asymptotic Properties, And Heavy Traffic Limits, Charles Knessl, Haishen Yao

Publications and Research

We consider two parallel queues, each with independent Poisson arrival rates, that are tended by a single server. The exponential server devotes all of its capacity to the longer of the queues. If both queues are of equal length, the server devotes of its capacity to the first queue and the remaining to the second. We obtain exact integral representations for the joint probability distribution of the number of customers in this two-node network. Then we evaluate this distribution in various asymptotic limits, such as large numbers of customers in either/both of the queues, light traffic where arrivals are infrequent, …


Centerline Extraction For Image Segmentation Using Gradient And Direction Vector Flow Active Contours, Shuqun Zhang, Jianyang Zhou Jan 2013

Centerline Extraction For Image Segmentation Using Gradient And Direction Vector Flow Active Contours, Shuqun Zhang, Jianyang Zhou

Publications and Research

In this paper, we propose a fast centerline extraction method to be used for gradient and direction vector flow of active contours. The gradient and direction vector flow is a recently reported active contour model capable of significantly improving the image segmentation performance especially for complex object shape, by seamlessly integrating gradient vector flow and prior directional information. Since the prior directional information is provided by manual line drawing, it can be inconvenient for inexperienced users who might have difficulty in finding the best place to draw the directional lines to achieve the best segmentation performance. This paper describes a …