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Articles 10441 - 10470 of 12810

Full-Text Articles in Physical Sciences and Mathematics

Achieving Coordination Through Dynamic Construction Of Open Workflows, Louis Thomas, Justin Wilson, Grui-Catalin Roman, Christopher Gill Jan 2009

Achieving Coordination Through Dynamic Construction Of Open Workflows, Louis Thomas, Justin Wilson, Grui-Catalin Roman, Christopher Gill

All Computer Science and Engineering Research

Workflow middleware executes tasks orchestrated by rules defined in a carefully handcrafted static graph. Workflow management systems have proved effective for service-oriented business automation in stable, wired infrastructures. We introduce a radically new paradigm for workflow construction and execution called open workflow to support goal-directed coordination among physically mobile people and devices that form a transient community over an ad hoc wireless network. The quintessential feature of the open workflow paradigm is dynamic construction of custom, context-specific workflows in response to unpredictable and evolving circumstances by exploiting the knowledge and services available within a given spatiotemporal context. This paper introduces …

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Defending Against Distributed Denial-Of-Service Attacks With Weight-Fair Router Throttling, Abusayeed Saifullah Jan 2009

Defending Against Distributed Denial-Of-Service Attacks With Weight-Fair Router Throttling, Abusayeed Saifullah

All Computer Science and Engineering Research

A high profile internet server is always a target of denial-of-service attacks. In this paper, we propose a novel technique for protecting an internet server from distributed denial-of-service attacks. The defense mechanism is based on a distributed algorithm that performs weight-fair throttling at the upstream routers. The throttling is weight-fair because the traffics destined for the server are controlled increased or decreased ) by the leaky-buckets at the routers based on the number of users connected, directly or through other routers, to each router. To the best of our knowledge, this is the first weight-fair technique for saving an internet …

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Augmented Lagrangian Algorithms Under Constraint Partitioning, You Xu, Yixin Chen Jan 2009

Augmented Lagrangian Algorithms Under Constraint Partitioning, You Xu, Yixin Chen

All Computer Science and Engineering Research

We present a novel constraint-partitioning approach for solving continuous nonlinear optimization based on augmented Lagrange method. In contrast to previous work, our approach is based on a new constraint partitioning theory and can handle global constraints. We employ a hyper-graph partitioning method to recognize the problem structure. We prove global convergence under assumptions that are much more relaxed than previous work and solve problems as large as 40,000 variables that other solvers such as IPOPT [11] cannot solve.

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Achieving Coordination Through Dynamic Construction Of Open Workflows ** Please See Wucse-2009-14 **, Louis Thomas, Justin Luner, Grui-Catalin Roman, Christopher Gill Jan 2009

Achieving Coordination Through Dynamic Construction Of Open Workflows ** Please See Wucse-2009-14 **, Louis Thomas, Justin Luner, Grui-Catalin Roman, Christopher Gill

All Computer Science and Engineering Research

Workflows, widely used on the Internet today, typically consist of a graph-like structure that defines the orchestration rules for executing a set of tasks, each of which is matched at run-rime to a corresponding service. The graph is static, specialized directories enable the discovery of services, and the wired infrastructure supports routing of results among tasks. In this paper we introduce a radically new paradigm for workflow construction and execution called open workflow. It is motivated by the growing reliance on wireless ad hoc networks in settings such as emergency response, field hospitals, and military operations. Open workflows facilitate goal-directed …

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Enabling A Low-Delay Internet Service Via Built-In Performance Incentives, Maxim Podlesny, Sergey Gorinsky Jan 2009

Enabling A Low-Delay Internet Service Via Built-In Performance Incentives, Maxim Podlesny, Sergey Gorinsky

All Computer Science and Engineering Research

The single best-effort service of the Internet struggles to accommodate divergent needs of different distributed applications. Numerous alternative network architectures have been proposed to offer diversified network services. These innovative solutions failed to gain wide deployment primarily due to economic and legacy issues rather than technical shortcomings. Our paper presents a new simple paradigm for network service differentiation that accounts explicitly for the multiplicity of Internet service providers and users as well as their economic interests in environments with partly deployed new services. Our key idea is to base the service differentiation on performance itself, rather than price. We design …

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The Virtual Network Scheduling Problem For Heterogeneous Network Emulation Testbeds, Charlie Wisemen, Jonathan Turner Jan 2009

The Virtual Network Scheduling Problem For Heterogeneous Network Emulation Testbeds, Charlie Wisemen, Jonathan Turner

All Computer Science and Engineering Research

Network testbeds such as Emulab and the Open Network Laboratory use virtualization to enable users to define end user virtual networks within a shared substrate. This involves mapping users' virtual network nodes onto distinct substrate components and mapping virtual network links onto substrate paths. The mappings guarantee that different users' activities can not interfere with one another. The problem of mapping virtual networks onto a shared substrate is a variant of the general graph embedding problem, long known to be NP-hard. In this paper, we focus on a more general version of the problem that supports advance scheduling of virtual …

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Design And Evaluation Of A Practical, High Performance Crossbar Scheduler, Jonathan Turner Jan 2009

Design And Evaluation Of A Practical, High Performance Crossbar Scheduler, Jonathan Turner

All Computer Science and Engineering Research

The Least Occupied Output First (LOOFA) scheduler is one of several unbuffered crossbar schedulers that provides strong performance guarantees when operated with a speedup of 2 or more. Because LOOFA requires the computation of a maximal matching, it has been considered too slow for use in systems with link rates of 10 Gb/s or more. This paper studies an approximate variant of LOOFA described briefly in [16]. We introduce a general family of schedulers that allows for partial sorting and that includes the LOOFA scheduler as a special case. We show that all schedulers in this class are work-conserving and …

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Open Workflows: Context-Dependent Construction And Execution In Mobile Wireless Settings, Louis Thomas, Justin Wilson, Grui-Catalin Roman, Christopher Gill Jan 2009

Open Workflows: Context-Dependent Construction And Execution In Mobile Wireless Settings, Louis Thomas, Justin Wilson, Grui-Catalin Roman, Christopher Gill

All Computer Science and Engineering Research

Existing workflow middleware executes tasks orchestrated by rules defined in a carefully handcrafted static graph. Workflow management systems have proved effective for service-oriented business automation in stable, wired infrastructures. We introduce a radically new paradigm for workflow construction and execution called open workflow to support goal-directed coordination among physically mobile people and devices that form a transient community over an ad hoc wireless network. The quintessential feature of the open workflow paradigm is dynamic construction and execution of custom, context-specific workflows in response to unpredictable and evolving circumstances by exploiting the knowledge and services available within a given spatiotemporal context. …

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Design Of An Extensible Network Testbed With Heterogeneous Components, Charlie Wisemen, Jyoti Parwatikar, Ken Wong, John Dehart, Jonathan Turner Jan 2009

Design Of An Extensible Network Testbed With Heterogeneous Components, Charlie Wisemen, Jyoti Parwatikar, Ken Wong, John Dehart, Jonathan Turner

All Computer Science and Engineering Research

Virtualized network infrastructures are currently deployed in both research and commercial contexts. The complexity of the virtualization layer varies greatly in different deployments, ranging from cloud computing environments, to carrier Ethernet applications using stacked VLANs, to networking testbeds. In all of these cases, there are many users sharing the resources of one provider, where each user expects their resources to be isolated from all other users. Our work in this area is focused on network testbeds. In particular, we present the design of the latest version of the Open Network Laboratory (ONL) testbed. This redesign generalizes the underlying infrastructure to …

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Feedback Thermal Control For Real-Time Systems, Yong Fu, Nicholas Kottenstette, Yingming Chen, Chenyang Lu, Xenofon D. Koutsoukos, Hongan Wang Jan 2009

Feedback Thermal Control For Real-Time Systems, Yong Fu, Nicholas Kottenstette, Yingming Chen, Chenyang Lu, Xenofon D. Koutsoukos, Hongan Wang

All Computer Science and Engineering Research

Thermal control is crucial to real-time systems as excessive processor temperature can cause system failure or unacceptable performance degradation due to hardware throttling. Real-time systems face significant challenges in thermal management as they must avoid processor overheating while still delivering desired real-time performance. Furthermore, many real-time systems must handle a broad range of uncertainties in system and environmental conditions. To address these challenges, this paper presents Thermal Control under Utilization Bound (TCUB), a novel thermal control algorithm specifically designed for real-time systems. TCUB employs a feedback control loop that dynamically controls both processor temperature and CPU utilization through task rate …

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Submodular Utility Optimization In Sensor Networks For Capacity Constraints, You Xu, Yixin Chen, Chenyang Lu, Sangeeta Bhattacharya, Abu Saifullah Jan 2009

Submodular Utility Optimization In Sensor Networks For Capacity Constraints, You Xu, Yixin Chen, Chenyang Lu, Sangeeta Bhattacharya, Abu Saifullah

All Computer Science and Engineering Research

With the fast development of wireless sensor network (WSN) technologies, WSNs have widely shifted from a specialized platform for a single application to an integrated infrastructure supporting multiple applications. It is hence a critical problem to allocate multiple applications to multiple sensors in order to maximize user utility subject to various resource constraints. The resulting constrained optimization problem is difficult since it is discrete, nonlinear, and not in closed-form. In this report, we develop an efficient optimization algorithm with rigorous approximation bounds for submodular monotonic optimization with multiple knapsack constraints. Based on a variance reduction formulation, we prove several important …

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Volumeviewer: An Interactive Tool For Fitting Surfaces To Volume Data, Ross Sowell, Lu Liu, Tao Ju, Cindy Grimm, Christopher Abraham, Garima Gokhroo, D Low Jan 2009

Volumeviewer: An Interactive Tool For Fitting Surfaces To Volume Data, Ross Sowell, Lu Liu, Tao Ju, Cindy Grimm, Christopher Abraham, Garima Gokhroo, D Low

All Computer Science and Engineering Research

Recent advances in surface reconstruction algorithms allow surfaces to be built from contours lying on non-parallel planes. Such algorithms allow users to construct surfaces of similar quality more efficiently by using a small set of oblique contours, rather than many parallel contours. However, current medical imaging systems do not provide tools for sketching contours on oblique planes. In this paper, we take the first steps towards bridging the gap between the new surface reconstruction technologies and putting those methods to use in practice. We develop a novel interface for modeling surfaces from volume data by allowing the user to sketch …

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On Unusual Pixel Shapes And Image Motion, Nathan Jacobs, Stephen Schuh, Robert Pless Jan 2009

On Unusual Pixel Shapes And Image Motion, Nathan Jacobs, Stephen Schuh, Robert Pless

All Computer Science and Engineering Research

We introduce the integral-pixel camera model, where measurements integrate over large and potentially overlapping parts of the visual field. This models a wide variety of novel camera designs, including omnidirectional cameras, compressive sensing cameras, and novel programmable-pixel imaging chips. We explore the relationship of integral-pixel measurements with image motion and find (a) that direct motion estimation using integral-pixels is possible and in some cases quite good, (b) standard compressive-sensing reconstructions are not good for estimating motion, and (c) when we design image reconstruction algorithms that explicitly reason about image motion, they outperform standard compressive-sensing video reconstruction. We show experimental results …

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The Design And Performance Of Cyber-Physical Middleware For Real-Time Hybrid Structural Testing, Huang-Ming Huang, Xiuyu Gao, Terry Tidewell, Christopher Gill Jan 2009

The Design And Performance Of Cyber-Physical Middleware For Real-Time Hybrid Structural Testing, Huang-Ming Huang, Xiuyu Gao, Terry Tidewell, Christopher Gill

All Computer Science and Engineering Research

Real-time hybrid testing of civil structures, in which computational models and physical components must be integrated with high fidelity at run-time represents a grand challenge in the emerging area of cyber-physical systems. Actuator dynamics, complex interactions among computers and physical components, and computation and communication delays all must be managed carefully to achieve accurate tests. To address these challenges, we have developed a novel middleware for integrating cyber and physical components flexibly and with suitable timing behavior within a Cyber-physical Instrument for Real-time hybrid Structural Testing (CIRST). This paper makes three main contributions to the state of the art in …

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Non-Programmers Identifying Functionality In Unfamiliar Code: Strategies And Barriers, Paul Gross, Caitlin Kelleher Jan 2009

Non-Programmers Identifying Functionality In Unfamiliar Code: Strategies And Barriers, Paul Gross, Caitlin Kelleher

All Computer Science and Engineering Research

Source code on the web is a widely available and potentially rich learning resource for non-programmers. However, unfamiliar code can be daunting to end-users without programming experience. This paper describes the results of an exploratory study in which we asked non-programmers to find and modify the code responsible for specific functionality within unfamiliar programs. We present two interacting models of how non-programmers approach this problem: the Task Process Model and the Landmark-Mapping model. Using these models, we describe code search strategies non-programmers employed and the difficulties they encountered. Finally, we propose guidelines for future programming environments that support non-programmers in …

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Online Bayesian Analysis, Ruibin Xi, Yongjin Kim, Nan Lin, Yixin Chen, Gruia-Catalin Roman Jan 2009

Online Bayesian Analysis, Ruibin Xi, Yongjin Kim, Nan Lin, Yixin Chen, Gruia-Catalin Roman

All Computer Science and Engineering Research

In the last few years, there has been active research on aggregating advanced statistical measures in multidimensional data cubes from partitioned subsets of data. In this paper, we propose an online compression and aggregation scheme to support Bayesian estimations in data cubes based on the asymptotic properties of Bayesian statistics. In the proposed approach, we compress each data segment by retaining only the model parameters and a small amount of auxiliary measures. We then develop an aggregation formula that allows us to reconstruct the Bayesian estimation from partitioned segments with a small approximation error. We show that the Bayesian estimates …

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Detection Of Steganography-Producing Software Artifacts On Crime-Related Seized Computers, Asawaree Kulkarni, James Goldman, Brad Nabholz, William Eyre Jan 2009

Detection Of Steganography-Producing Software Artifacts On Crime-Related Seized Computers, Asawaree Kulkarni, James Goldman, Brad Nabholz, William Eyre

Journal of Digital Forensics, Security and Law

Steganography is the art and science of hiding information within information so that an observer does not know that communication is taking place. Bad actors passing information using steganography are of concern to the national security establishment and law enforcement. An attempt was made to determine if steganography was being used by criminals to communicate information. Web crawling technology was used and images were downloaded from Web sites that were considered as likely candidates for containing information hidden using steganographic techniques. A detection tool was used to analyze these images. The research failed to demonstrate that steganography was prevalent on …

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Book Review: Cyber Security And Global Information Assurance: Threat Analysis And Response Solutions, Gary C. Kessler Jan 2009

Book Review: Cyber Security And Global Information Assurance: Threat Analysis And Response Solutions, Gary C. Kessler

Journal of Digital Forensics, Security and Law

I freely admit that this book was sent to me by the publisher for the expressed purpose of my writing a review and that I know several of the chapter authors. With that disclosure out of the way, let me say that the book is well worth the review (and I get to keep my review copy).
The preface to the book cites the 2003 publication of The National Strategy to Secure Cyberspace by the White House, and the acknowledgement by the U.S. government that our economy and national security were fully dependent upon computers, networks, and the telecommunications infrastructure. …

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Prevention Is Better Than Prosecution: Deepening The Defence Against Cyber Crime, Jacqueline Fick Jan 2009

Prevention Is Better Than Prosecution: Deepening The Defence Against Cyber Crime, Jacqueline Fick

Journal of Digital Forensics, Security and Law

In the paper the author proposes that effectively and efficiently addressing cyber crime requires a shift in paradigm. For businesses and government departments alike the focus should be on prevention, rather than the prosecution of cyber criminals. The Defence in Depth strategy poses a practical solution for achieving Information Assurance in today’s highly networked environments. In a world where “absolute security” is an unachievable goal, the concept of Information Assurance poses significant benefits to securing one of an organization’s most valuable assets: Information. It will be argued that the approach of achieving Information Assurance within an organisation, coupled with the …

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Bluetooth Hacking: A Case Study, Dennis Browning, Gary C. Kessler Jan 2009

Bluetooth Hacking: A Case Study, Dennis Browning, Gary C. Kessler

Journal of Digital Forensics, Security and Law

This paper describes a student project examining mechanisms with which to attack Bluetooth-enabled devices. The paper briefly describes the protocol architecture of Bluetooth and the Java interface that programmers can use to connect to Bluetooth communication services. Several types of attacks are described, along with a detailed example of two attack tools, Bloover II and BT Info.

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Table Of Contents Jan 2009

Table Of Contents

Journal of Digital Forensics, Security and Law

No abstract provided.

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An Intelligent Face Features Generation System From Fingerprints, Şeref Sağiroğlu, Necla Özkaya Jan 2009

An Intelligent Face Features Generation System From Fingerprints, Şeref Sağiroğlu, Necla Özkaya

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, a novel intelligent system based on artificial neural networks was designed and introduced for generating faces from fingerprints with high accuracy. The proposed system has a number of modules including two feature enrolment modules for acquiring the fingerprints and faces into the system, two feature extractors for extracting the feature sets of fingerprint and face biometrics, an artificial neural network module that was configured with the help of Taguchi experimental design method for establishing relationships among the biometric features, a face re-constructor for building up face features from the results of the system, and a test module …

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Modeling And Calculation Of Electromagnetic Field In The Surroundings Of A Large Power Transformer, Leonardo Strac, Franjo Kelemen, Damir Zarko Jan 2009

Modeling And Calculation Of Electromagnetic Field In The Surroundings Of A Large Power Transformer, Leonardo Strac, Franjo Kelemen, Damir Zarko

Turkish Journal of Electrical Engineering and Computer Sciences

The presented study compares measured and calculated electromagnetic field quantities in the surroundings of a large power transformer with the aim to avoid the necessity of measuring the field on subsequent units and use a computer model instead. The influences of various objects located in the vicinity of the transformer during measurement are also analyzed and are taken into account in a computer model.

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Geodesic Grassfire For Computing Mixed-Dimensional Skeletons, Lu Liu, Tao Ju Jan 2009

Geodesic Grassfire For Computing Mixed-Dimensional Skeletons, Lu Liu, Tao Ju

All Computer Science and Engineering Research

Skeleton descriptors are commonly used to represent, understand and process shapes. While existing methods produce skeletons at a fixed dimension, such as surface or curve skeletons for a 3D object, often times objects are better described using skeleton geometry at a mixture of dimensions. In this paper we present a novel algorithm for computing mixed-dimensional skeletons. Our method is guided by a continuous analogue that extends the classical grassfire erosion. This analogue allows us to identify medial geometry at multiple dimensions, and to formulate a measure that captures how well an object part is described by medial geometry at a …

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Partial Program Admission, Michael Wilson, Ron Cytron, Jon Turner Jan 2009

Partial Program Admission, Michael Wilson, Ron Cytron, Jon Turner

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Real-time systems on non-preemptive platforms require a means of bounding the execution time of programs for admission purposes. Worst-Case Execution Time (WCET) is most commonly used to bound program execution time. While bounding a program’s WCET statically is possible, computing its true WCET is difficult.We present a new technique we call partial program admission, a means of statically enforcing an otherwise untrusted assertion of WCET without adding runtime overhead, by means of code duplication. We apply this technique to real programs from the virtual networking arena and present the results.

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Radio Mapping For Indoor Environments, Octav Chipara, Gregory Hackmann, Chenyang Lu, William D. Smart Jan 2009

Radio Mapping For Indoor Environments, Octav Chipara, Gregory Hackmann, Chenyang Lu, William D. Smart

All Computer Science and Engineering Research

The efficient deployment and robust operation of many sensor network applications depend on deploying relays to ensure wireless coverage. Radio mapping aims to predict network coverage based on a small number of link measurements from sampled locations. Radio mapping is particularly challenging in complex indoor environments where walls significantly affect radio signal propagation. This paper makes the following key contributions to indoor radio mapping. First, our empirical study in an office building identifies a wall-classification model as the most effective model for indoor environments due to its balance between model complexity and accuracy. Second, we propose a practical algorithm to …

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Enhanced Coordination In Sensor Networks Through Flexible Service Provisioning, Chien-Liang Fok, Gruia-Catalin Roman, Chenyang Lu Jan 2009

Enhanced Coordination In Sensor Networks Through Flexible Service Provisioning, Chien-Liang Fok, Gruia-Catalin Roman, Chenyang Lu

All Computer Science and Engineering Research

Heterogeneous wireless sensor networks represent a challenging programming environment. Servilla addresses this by offering a new middleware framework that provides service provisioning. Using Servilla, developers can construct platform-independent applications over a dynamic set of devices with diverse computational resources and sensors. A salient feature of Servilla is its support for dynamic discovery and binding to local and remote services, which enables flexible and energy-efficient in-network collaboration among heterogeneous devices. Furthermore, Servilla provides a modular middleware architecture that can be easily tailored for devices with a wide range of resources, allowing resource-constrained devices to provide services while leveraging the capabilities of …

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Reliable Patient Monitoring: A Clinical Study In A Step-Down Hospital Unit, Octav Chipara, Chenyang Lu, Thomas C. Bailey, Gruia-Catalin Roman Jan 2009

Reliable Patient Monitoring: A Clinical Study In A Step-Down Hospital Unit, Octav Chipara, Chenyang Lu, Thomas C. Bailey, Gruia-Catalin Roman

All Computer Science and Engineering Research

This paper presents the design, deployment, and empirical study of a wireless clinical monitoring system that collects pulse and oxygen saturation readings from patients. The primary contribution of this paper is an in-depth clinical trial that assesses the feasibility of wireless sensor networks for patient monitoring in general (non-ICU) hospital units. The trial involved 32 patients monitored in a step-down cardiology unit at Barnes-Jewish Hospital, St. Louis. During a total of 31 days of monitoring, the network achieved high reliability (median 99.92%, range 95.21% - 100%). The overall reliability of the system was dominated by sensing reliability (median 80.55%, range …

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A Mobile Ecg Monitoring System With Context Collection, Jin Peng Li, Damon Berry, Richard Hayes Jan 2009

A Mobile Ecg Monitoring System With Context Collection, Jin Peng Li, Damon Berry, Richard Hayes

Conference Papers

Preventative health management represents a shift from the traditional approach of reactive treatment-based healthcare towards a proactive wellness-management approach where patients are encouraged to stay healthy with expert support when they need it, at any location and any time. This work represents a step along the road towards proactive, preventative healthcare for cardiac patients. It seeks to develop a smart mobile ECG monitoring system that requests and records context information about what is happening around the subject when an arrhythmia event occurs. Context information about the subject’s activities of daily living will, it is hoped, provide an enriched data set …

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Parameter Identification Of A Separately Excited Dc Motor Via Inverse Problem Methodology, Mounir Hadef, Mohamed Rachid Mekideche Jan 2009

Parameter Identification Of A Separately Excited Dc Motor Via Inverse Problem Methodology, Mounir Hadef, Mohamed Rachid Mekideche

Turkish Journal of Electrical Engineering and Computer Sciences

Identification is considered to be among the main applications of inverse theory and its objective for a given physical system is to use data which is easily observable, to infer some of the geometric parameters which are not directly observable. In this paper, a parameter identification method using inverse problem methodology is proposed. The minimisation of the objective function with respect to the desired vector of design parameters is the most important procedure in solving the inverse problem. The conjugate gradient method is used to determine the unknown parameters, and Tikhonov's regularization method is then used to replace the original …

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