Duke University

Displaying 1-40 of 109 results

  • White Papers // Apr 2014

    Experiences in Developing and Evaluating a Low-Cost Soft-Error-Tolerant Multicore Processor

    To tolerate soft errors - which requires both detecting the errors and recovering from their effects - industry and academia have developed a wide variety of approaches. Holistic approaches like N-Modulo Redundancy (NMR) are too expensive, in terms of power and area, for all but the most critical applications. The...

    Provided By Duke University

  • White Papers // Mar 2014

    A Throughput-Oriented Approach to Release Consistency on GPUs

    Graphics Processing Units (GPUs) have specialized throughput-oriented memory systems optimized for streaming writes with scratchpad memories to capture locality explicitly. Expanding the utility of GPUs beyond graphics encourages designs that simplify programming (e.g., using caches instead of scratchpads) and better support irregular applications with finer-grain synchronization. The authors' hypothesis is...

    Provided By Duke University

  • White Papers // Feb 2014

    Scalably Verifiable Dynamic Power Management

    Dynamic Power Management (DPM) is critical to maximizing the performance of systems ranging from multicore processors to datacenters. However, one formidable challenge with DPM schemes is verifying that the DPM schemes are correct as the number of computational resources scales up. In this paper, the authors develop a DPM scheme...

    Provided By Duke University

  • White Papers // Jan 2014

    Bayesian Conditional Density Filtering for Big Data

    The authors propose a Conditional Density Filtering (C-DF) algorithm for efficient online Bayesian inference. C-DF adapts Gibbs sampling to the online setting, sampling from approximations to conditional posterior distributions obtained by tracking of surrogate conditional sufficient statistics as new data arrive. This tracking eliminates the need to store or process...

    Provided By Duke University

  • White Papers // Jan 2014

    A Dynamic Approach to thread Scheduling in Hardware (DASH)

    As thread level parallelism in applications has continued to grow, research in Chip Multi-Processors (CMPs) has continued to expand. Recent calls by industry have led researchers to develop new techniques for writing multithreaded programs for non-server applications. In these programs thread level parallelism will no longer be at the embarrassingly...

    Provided By Duke University

  • White Papers // Dec 2013

    Exploiting Emerging Technologies for Nanoscale Photonic Networks-on-Chip

    In this paper, the authors explore the use of emerging molecular scale devices to construct nanophotonic networks - called molecular-scale Network-on-Chip (mNoC). They leverage quantum dot LEDs, which provide electrical to optical signal modulation, and chromophores, which provide optical signal filtering for receivers. These devices replace the ring resonators and...

    Provided By Duke University

  • White Papers // Jun 2013

    Understanding the Critical Path in Power State Transition Latencies

    Increasing demands on datacenter computing prompts research in energy-efficient warehouse scale systems. In one approach, server activation policies invoke low-power sleep states but the power state transition latency must be small to produce effective energy savings. Chrome OS and Arch Linux require 50ms and 650ms, respectively, to enter sleep states....

    Provided By Duke University

  • White Papers // Jun 2013

    Disintegrated Control for Energy-Efficient and Heterogeneous Memory Systems

    A mix of emerging technologies promises qualitatively new memory system capabilities. However, today's memory controllers and channels constrain heterogeneity. Today's integration of controllers on processor dies prevents systems from accommodating diverse, technology-specific protocols and schedulers in a modular manner; memory design decisions must be made during processor design. Moreover, today's...

    Provided By Duke University

  • White Papers // Jun 2013

    mNoC: Large Nanophotonic Network-on-Chip Crossbars with Molecular Scale Devices

    Moore's law and the continuity of device scaling have led to an increasing number of cores/nodes on a chip, creating a need for new mechanisms to achieve high-performance and power efficient Network-on-Chip (NoC). Nanophotonics based NoCs provide for higher bandwidth and more power efficient designs than electronic networks. Present approaches...

    Provided By Duke University

  • White Papers // Jun 2013

    Sequential Consistency for Heterogeneous-Race-Free Programmer-centric Memory Models for Heterogeneous Platforms

    Hardware vendors now provide heterogeneous platforms in commodity markets (e.g., integrated CPUs and GPUs), and are promising an integrated, shared memory address space for such platforms in future iterations. Because not all threads in a heterogeneous platform can communicate with the same latency, vendors are proposing synchronization mechanisms that allow...

    Provided By Duke University

  • White Papers // Apr 2013

    Data Secrecy in Distributed Storage Systems under Exact Repair

    The problem of securing data against eavesdropping in distributed storage systems is studied. The focus is on systems that use linear codes and implement exact repair to recover from node failures. The maximum file size that can be stored securely is determined for systems in which all the available nodes...

    Provided By Duke University

  • White Papers // Dec 2012

    Differential Privacy and Statistical Disclosure Risk Measures: An Investigation with Binary Synthetic Data

    The authors compare the disclosure risk criterion of ?-differential privacy with a criterion based on probabilities that intruders uncover actual values given the released data. To do so, they generate fully synthetic data that satisfy ?-differential privacy at different levels of ?, make assumptions about the information available to intruders,...

    Provided By Duke University

  • White Papers // Nov 2012

    Inferred Models for Dynamic and Sparse Hardware-Software Spaces

    Diverse software and heterogeneous hardware pose new challenges in systems and architecture management. Managers benefit from improving introspective capabilities, which provide data across a spectrum of platforms, from software and datacenter profilers to performance counters and canary circuits. Despite this wealth of data, management has become more difficult as sophisticated...

    Provided By Duke University

  • White Papers // Oct 2012

    Writing Cosets of a Convolutional Code to Increase the Lifetime of Flash Memory

    In this paper, the authors extend the lifetime of flash memory by reducing the frequency with which a given page of memory is erased. This is accomplished by increasing the number of writes that are possible before erasure is necessary. Redundancy is introduced into the write process to decrease the...

    Provided By Duke University

  • White Papers // May 2012

    The Limits of Concurrency in Cache Coherence

    In this paper, the authors has shown how to improve the performance of cache coherence protocols by using logical time to enable concurrency that would not be legal in physical time. They hypothesized that extending this prior work to enable even greater concurrency would further improve performance, and they developed...

    Provided By Duke University

  • White Papers // Jan 2012

    Efficient Peer-To-Peer Keyword Searching

    The recent file storage applications built on top of peer-to-peer distributed hash tables lack search capabilities. The authors believe that search is an important part of any document publication system. To that end, they have designed and analyzed a distributed search engine based on a distributed hash table. Their simulation...

    Provided By Duke University

  • White Papers // Sep 2011

    Algorithms for Constructing Overlay Networks for Live Streaming

    In this paper, the authors present a polynomial time approximation algorithm for constructing an overlay multicast network for streaming live media events over the Internet. The class of overlay networks constructed by their algorithm includes networks used by Akamai Technologies to deliver live media events to a global audience with...

    Provided By Duke University

  • White Papers // Sep 2011

    Assessing the Veracity of Identity Assertions via OSNs

    Anonymity is one of the main virtues of the Internet, as it protects privacy and enables users to express opinions more freely. However, anonymity hinders the assessment of the veracity of assertions that online users make about their identity attributes, such as age or profession. The authors propose FaceTrust, a...

    Provided By Duke University

  • White Papers // Sep 2011

    Confidant: Protecting OSN Data Without Locking It Up

    Online Social Networks (OSNs) are immensely popular, but participants are increasingly uneasy with centralized services' handling of user data. Decentralized OSNs offer the potential to address user's anxiety while also enhancing the features and scalability offered by existing, centralized services. In this paper, the authors present Confidant, a decentralized OSN...

    Provided By Duke University

  • White Papers // Jun 2011

    For Here or to Go: Predicting Client Dwell Time in WiFi Hotspots

    Modern mobile phones provide a plethora of sensors, enabling high-resolution measurement of the user's behavior. Further, user behaviors are not random-detailed measurements of current activities can be suggestive of the near future. The authors envision that such behavioral insights can help deliver enhanced network services. While behavior-aware networking is a...

    Provided By Duke University

  • White Papers // May 2011

    Frame Coherence and Sparse Signal Processing

    The sparse signal processing literature often uses random sensing matrices to obtain performance guarantees. Unfortunately, in the real world, sensing matrices do not always come from random processes. It is therefore desirable to evaluate whether an arbitrary matrix, or frame, is suitable for sensing sparse signals. To this end, the...

    Provided By Duke University

  • White Papers // May 2011

    Dealing Proactively With Data Corruption: Challenges and Opportunities

    The danger of production or backup data becoming corrupted is a problem that database administrators dread. This paper aims to bring this problem to the attention of the database research community, which, surprisingly, has by and large overlooked this problem. The authors begin by pointing out the causes and consequences...

    Provided By Duke University

  • White Papers // May 2011

    A Hierarchical Model to Evaluate Quality of Experience of Online Services Hosted by Cloud Computing

    As online service providers utilize cloud computing to host their services, they are challenged by evaluating the quality of experience and designing redirection strategies in this complicated environment. The authors propose a hierarchical modeling approach that can easily combine all components of this environment. Identifying interactions among the components is...

    Provided By Duke University

  • White Papers // Apr 2011

    Fast Level Set Estimation From Projection Measurements

    Estimation of the level set of a function (i.e., regions where the function exceeds some value) is an important problem with applications in digital elevation maps, medical imaging, and astronomy. In many applications, however, the function of interest is acquired through indirect measurements, such as tomographic projections, coded-aperture measurements, or...

    Provided By Duke University

  • White Papers // Mar 2011

    No Time to Countdown: Migrating Backoff to the Frequency Domain

    Conventional WiFi networks perform channel contention in time domain. This is known to be wasteful because the channel is forced to remain idle, while all contending nodes are backing off for multiple time slots. This paper proposes to break away from convention and recreate the backing off operation in the...

    Provided By Duke University

  • White Papers // Mar 2011

    Precise Indoor Localization Using PHY Layer Information

    This paper shows the viability of precise indoor localization using physical layer information in WiFi systems. The authors find that channel frequency responses across multiple OFDM subcarriers can be suitably aggregated into a location signature. While these signatures vary over time and environmental mobility, they notice that their core structure...

    Provided By Duke University

  • White Papers // Feb 2011

    On the Identification of Parametric Underspread Linear Systems

    Identification of time-varying linear systems, which introduce both time-shifts (delays) and frequency-shifts (Doppler-shifts), is a central task in many engineering applications. This paper studies the problem of identification of Under-spread Linear Systems (ULSs), defined as time-varying linear systems whose responses lie within a unit-area region in the delay - Doppler...

    Provided By Duke University

  • White Papers // Feb 2011

    Identification of Parametric Underspread Linear Systems and Super-Resolution Radar

    Identification of time-varying linear systems, which introduce both time-shifts (delays) and frequency-shifts (Doppler-shifts), is a central task in many engineering applications. This paper studies the problem of identification of Underspread Linear Systems (ULSs), whose responses lie within a unit-area region in the delay - Doppler space, by probing them with...

    Provided By Duke University

  • White Papers // Feb 2011

    Brand Names Act Like Marketing Placebos

    This paper illustrates the power of reputation, such as that embodied in brand names, demonstrating that names can enhance objective product efficacy. Study participants facing a glaring light were asked to read printed words as accurately and as quickly as they could, receiving compensation proportional to their performance. Those wearing...

    Provided By Duke University

  • White Papers // Jan 2011

    The Resilience of WDM Networks to Probabilistic Geographical Failures

    Telecommunications networks, and in particular optical WDM networks, are vulnerable to large-scale failures of their physical infrastructure, resulting from physical attacks (such as an Electromagnetic Pulse attack) or natural disasters (such as solar flares, earthquakes, and floods). Such events happen at specific geographical locations and disrupt specific parts of the...

    Provided By Duke University

  • White Papers // Jan 2011

    In-Vehicle Driver Detection Using Mobile Phone Sensors

    The authors present a mobile phone based sensing system to determine if a mobile user in an automobile is the driver or a passenger. This can help the mobile device to be aware of the user's attention span and control the delivery of notifications such as incoming calls and context...

    Provided By Duke University

  • White Papers // Jan 2011

    Automating Privacy Testing of Smartphone Applications

    Smartphones have revolutionized mobile computing, but have created concerns that many third-party mobile applications do not properly handle users' privacy-sensitive data. This paper proposes AppInspector, an automated privacy validation system that analyzes apps and generates reports of potential privacy risks. A key insight is that distinguishing acceptable disclosures from privacy...

    Provided By Duke University

  • White Papers // Jan 2011

    Computational Journalism: A Call to Arms to Database Researchers

    The digital age has brought sweeping changes to the news media. While online consumption of news is on the rise, fewer people today read newspapers. Newspaper advertising revenues fell by a total of 23% in 2007 and 2008, and tumbled 26% more in 2009. This continuing decline of the traditional...

    Provided By Duke University

  • White Papers // Jan 2011

    Starfish: A Selftuning System for Big Data Analytics

    Timely and cost-effective analytics over "Big Data" is now a key ingredient for success in many businesses, scientific and engineering disciplines, and government endeavors. The Hadoop software stack - which consists of an extensible MapReduce execution engine, pluggable distributed storage engines, and a range of procedural to declarative interfaces -...

    Provided By Duke University

  • White Papers // Jan 2011

    Harnessing Virtual Machine Resource Control for Job Management

    Virtual machine technology promises important benefits for grid computing and cluster batch job systems, including improved isolation, customizable workspaces, and support for checkpointing and migration. One way to gain these benefits is to "Drill holes" in existing batch computing systems; however, the authors believe these new capabilities warrant a rethinking...

    Provided By Duke University

  • White Papers // Jan 2011

    Managing Mixed-Use Clusters With Cluster-on-Demand

    Although clusters offer inexpensive computing power, they are difficult and expensive to manage, particularly for user communities with diverse software needs. This paper presents Cluster-On-Demand (COD), a cluster operating system framework for mixed-use clusters. COD interposes on standard network management services - DHCP, NIS, and DNS - to partition a...

    Provided By Duke University

  • White Papers // Jan 2011

    ConSil: Low-Cost Thermal Mapping of Data Centers

    Several projects involving high-level thermal management - such as eliminating "Hot spots" or reducing cooling costs through intelligent workload placement - require ambient air temperature readings at a fine granularity. Unfortunately, current thermal instrumentation methods involve installing a set of expensive hardware sensors. Modern motherboards include multiple on-board sensors, but...

    Provided By Duke University

  • White Papers // Jan 2011

    Dynamic Virtual Clusters in a Grid Site Manager

    This paper presents new mechanisms for dynamic resource management in a cluster manager called Cluster-On-Demand (COD). COD allocates servers from a common pool to multiple virtual clusters (vclusters), with independently configured software environments, name spaces, user access controls, and network storage volumes. The authors' present experiments using the popular Sun...

    Provided By Duke University

  • White Papers // Jan 2011

    Weatherman: Automated, Online, and Predictive Thermal Mapping and Management for Data Centers

    Recent advances have demonstrated the potential benefits of coordinated management of thermal load in data centers, including reduced cooling costs and improved resistance to cooling system failures. A key unresolved obstacle to the practical implementation of thermal load management is the ability to predict the effects of workload distribution and...

    Provided By Duke University

  • White Papers // Jan 2011

    Virtual Machine Hosting for Networked Clusters: Building the Foundations for "Autonomic" Orchestration

    Virtualization technology offers powerful resource management mechanisms, including performance-isolating resource schedulers, live migration, and suspend/resume. But how should networked virtual computing systems use these mechanisms? A grand challenge is to devise practical policies to drive these mechanisms in a self-managing or "Autonomic" system, without relying on human operators. This paper...

    Provided By Duke University

  • White Papers // Jan 2011

    The Resilience of WDM Networks to Probabilistic Geographical Failures

    Telecommunications networks, and in particular optical WDM networks, are vulnerable to large-scale failures of their physical infrastructure, resulting from physical attacks (such as an Electromagnetic Pulse attack) or natural disasters (such as solar flares, earthquakes, and floods). Such events happen at specific geographical locations and disrupt specific parts of the...

    Provided By Duke University

  • White Papers // Jan 2012

    Efficient Peer-To-Peer Keyword Searching

    The recent file storage applications built on top of peer-to-peer distributed hash tables lack search capabilities. The authors believe that search is an important part of any document publication system. To that end, they have designed and analyzed a distributed search engine based on a distributed hash table. Their simulation...

    Provided By Duke University

  • White Papers // Oct 2010

    Bootstrapping Accountability in the Internet We Have

    The lack of accountability makes the Internet vulnerable to numerous attacks, including prefix hijacking, route forgery, source address spoofing, and DoS flooding attacks. This paper takes a "Dirty-slate" approach to bring accountability to the present Internet with low-cost and deployable enhancements. The authors' design, IPA, uses the readily available top-level...

    Provided By Duke University

  • White Papers // Sep 2011

    Confidant: Protecting OSN Data Without Locking It Up

    Online Social Networks (OSNs) are immensely popular, but participants are increasingly uneasy with centralized services' handling of user data. Decentralized OSNs offer the potential to address user's anxiety while also enhancing the features and scalability offered by existing, centralized services. In this paper, the authors present Confidant, a decentralized OSN...

    Provided By Duke University

  • White Papers // Sep 2011

    Algorithms for Constructing Overlay Networks for Live Streaming

    In this paper, the authors present a polynomial time approximation algorithm for constructing an overlay multicast network for streaming live media events over the Internet. The class of overlay networks constructed by their algorithm includes networks used by Akamai Technologies to deliver live media events to a global audience with...

    Provided By Duke University

  • White Papers // May 2011

    Dealing Proactively With Data Corruption: Challenges and Opportunities

    The danger of production or backup data becoming corrupted is a problem that database administrators dread. This paper aims to bring this problem to the attention of the database research community, which, surprisingly, has by and large overlooked this problem. The authors begin by pointing out the causes and consequences...

    Provided By Duke University

  • White Papers // Apr 2009

    Automated Experiment-Driven Management of (Database) Systems

    In this paper, the authors argue that an important piece of the system administration puzzle has largely been left untouched by researchers. This piece involves mechanisms and policies to identify as well as collect missing instrumentation data; the missing data is essential to generate the knowledge required to address certain...

    Provided By Duke University

  • White Papers // Feb 2011

    Identification of Parametric Underspread Linear Systems and Super-Resolution Radar

    Identification of time-varying linear systems, which introduce both time-shifts (delays) and frequency-shifts (Doppler-shifts), is a central task in many engineering applications. This paper studies the problem of identification of Underspread Linear Systems (ULSs), whose responses lie within a unit-area region in the delay - Doppler space, by probing them with...

    Provided By Duke University

  • White Papers // May 2011

    Frame Coherence and Sparse Signal Processing

    The sparse signal processing literature often uses random sensing matrices to obtain performance guarantees. Unfortunately, in the real world, sensing matrices do not always come from random processes. It is therefore desirable to evaluate whether an arbitrary matrix, or frame, is suitable for sensing sparse signals. To this end, the...

    Provided By Duke University

  • White Papers // Apr 2011

    Fast Level Set Estimation From Projection Measurements

    Estimation of the level set of a function (i.e., regions where the function exceeds some value) is an important problem with applications in digital elevation maps, medical imaging, and astronomy. In many applications, however, the function of interest is acquired through indirect measurements, such as tomographic projections, coded-aperture measurements, or...

    Provided By Duke University

  • White Papers // Feb 2011

    On the Identification of Parametric Underspread Linear Systems

    Identification of time-varying linear systems, which introduce both time-shifts (delays) and frequency-shifts (Doppler-shifts), is a central task in many engineering applications. This paper studies the problem of identification of Under-spread Linear Systems (ULSs), defined as time-varying linear systems whose responses lie within a unit-area region in the delay - Doppler...

    Provided By Duke University

  • White Papers // Jan 2009

    Vis-a-Vis: Online Social Networking via Virtual Individual Servers

    Online Social Networks (OSNs) are immensely popular, but their centralized control of sensitive user data raises important privacy concerns. This paper presents Vis-'a-Vis, a decentralized framework for online social networking based on the privacy-preserving notion of a Virtual Individual Server (VIS), a personal virtual machine running within a cloud-computing utility....

    Provided By Duke University

  • White Papers // Jan 2011

    Computational Journalism: A Call to Arms to Database Researchers

    The digital age has brought sweeping changes to the news media. While online consumption of news is on the rise, fewer people today read newspapers. Newspaper advertising revenues fell by a total of 23% in 2007 and 2008, and tumbled 26% more in 2009. This continuing decline of the traditional...

    Provided By Duke University

  • White Papers // Jan 2011

    Starfish: A Selftuning System for Big Data Analytics

    Timely and cost-effective analytics over "Big Data" is now a key ingredient for success in many businesses, scientific and engineering disciplines, and government endeavors. The Hadoop software stack - which consists of an extensible MapReduce execution engine, pluggable distributed storage engines, and a range of procedural to declarative interfaces -...

    Provided By Duke University

  • White Papers // May 2010

    Time-consistent Majority Rules And Heterogenous Preferences In Group Decision-making

    This paper studies a collective decision problem in which a group of individuals with interdependent preferences vote whether or not to implement a public project of unknown value. A utilitarian social planner aggregates these votes according to a majority rule; but, unlike what is commonly assumed in the literature, the...

    Provided By Duke University

  • White Papers // Jul 2010

    Online Privacy And Price Discrimination

    When a firm is able to recognize its previous customers, it may use information about their purchase histories to price discriminate. The authors analyze a model with a monopolist and a continuum of heterogeneous consumers, where consumers are able to maintain their anonymity and avoid being identified as past customers,...

    Provided By Duke University

  • White Papers // Nov 2009

    Unobserved Heterogeneity And Reserve Prices In Auctions

    This paper addresses the need to account for unobserved heterogeneity in auctions to improve the authors' estimates of the distribution of bidder values. The method uses reserve prices to allow the distribution of bidders' private information to depend on the realization of the unobserved heterogeneity. The identifying assumption is that...

    Provided By Duke University

  • White Papers // May 2009

    Quality, Upgrades, And Equilibrium In A Dynamic Monopoly Model

    The authors examine an infinite horizon model of quality growth in a durable goods monopoly market. The monopolist generates new quality improvements over time and can sell any available qualities, in any desired bundles, at each point in time. Consumers are identical and for a quality improvement to have value...

    Provided By Duke University

  • White Papers // Jan 2011

    Harnessing Virtual Machine Resource Control for Job Management

    Virtual machine technology promises important benefits for grid computing and cluster batch job systems, including improved isolation, customizable workspaces, and support for checkpointing and migration. One way to gain these benefits is to "Drill holes" in existing batch computing systems; however, the authors believe these new capabilities warrant a rethinking...

    Provided By Duke University

  • White Papers // Jul 2009

    Have Economic Models' Forecasting Performance For US Output Growth And Inflation Changed Over Time, And When?

    The authors evaluate various economic models' relative performance in forecasting future US output growth and inflation on a monthly basis. The approach takes into account the possibility that the models' relative performance can be varying over time. They show that the models' relative performance has, in fact, changed dramatically over...

    Provided By Duke University

  • White Papers // Apr 2009

    The Impact Of The U.S. Financial Crisis On Global Retail Lending

    This paper examines the effects of the U.S. financial crisis on global lending to retail customers. In particular the authors examine retail bank lending in Germany taking advantage of a unique dataset of German savings banks over the period 2006-2008 for which they have the universe of loan applications and...

    Provided By Duke University

  • White Papers // Nov 2009

    Behavioral Finance: Capital Budgeting And Other Investment Decisions

    This paper surveys the literature on the effects of behavioral biases on capital budgeting. A large body of the psychology literature finds that people tend to be overconfident and overly optimistic. Because of self-selection, firm managers tend to be even more affected by these biases than the general population. Indeed,...

    Provided By Duke University

  • White Papers // Sep 2009

    Board Independence And Credit Ratings

    Using Sarbanes-OXley Act (SOX) as a natural experiment, the authors find evidence consistent with an optimal level of board independence for credit ratings. They test two hypotheses that could explain this optimality: Information Cost Hypothesis (ICH) that the effectiveness of independent boards increases with the private benefits of the management,...

    Provided By Duke University

  • White Papers // Jul 2010

    Autonomic Cloud Network Orchestration: A GENI Perspective

    Pervasive virtualization at the edge and in the network core drives the evolution of the IT infrastructure towards a service-oriented model. It permits a move from static arrangements of resources that persist over long periods of time to highly dynamic arrangements that respond to the needs of customers by dynamically...

    Provided By Duke University

  • White Papers // Aug 2010

    Quantifying Resiliency of IaaS Cloud

    Cloud based services may experience changes - internal, external, large, small - at any time. Predicting and quantifying the effects on the quality-of-service during and after a change are important in the resiliency assessment of a cloud based service. In this paper, the authors quantify the resiliency of Infrastructure-as-a-Service (IaaS)...

    Provided By Duke University

  • White Papers // Jan 2009

    Capital Gains Tax Overhang And Payout Policy

    Jin (2006) documents that tax-sensitive institutional investors with large embedded capital gains are reluctant to sell their shares, creating upward stock price pressure. This price pressure should reduce a firm's incentive to repurchase its shares. Consistent with this argument, the authors find that embedded capital gains of tax-sensitive institutional investors...

    Provided By Duke University

  • White Papers // Mar 2011

    No Time to Countdown: Migrating Backoff to the Frequency Domain

    Conventional WiFi networks perform channel contention in time domain. This is known to be wasteful because the channel is forced to remain idle, while all contending nodes are backing off for multiple time slots. This paper proposes to break away from convention and recreate the backing off operation in the...

    Provided By Duke University

  • White Papers // Mar 2011

    Precise Indoor Localization Using PHY Layer Information

    This paper shows the viability of precise indoor localization using physical layer information in WiFi systems. The authors find that channel frequency responses across multiple OFDM subcarriers can be suitably aggregated into a location signature. While these signatures vary over time and environmental mobility, they notice that their core structure...

    Provided By Duke University

  • White Papers // Jan 2009

    Mobicom Poster: SurroundSense: Mobile Phone Localization Using Ambient Sound and Light

    Proliferating mobile phones provide a foundation for revolutionary innovations in people-centric computing. Numerous applications are on the rise, many of which exploit the phone's location as the primary indicator of context. Existing physical localization schemes based on GPS/WiFi/GSM have been shown to achieve, at best, localization accuracy of several meters....

    Provided By Duke University

  • White Papers // Jun 2011

    For Here or to Go: Predicting Client Dwell Time in WiFi Hotspots

    Modern mobile phones provide a plethora of sensors, enabling high-resolution measurement of the user's behavior. Further, user behaviors are not random-detailed measurements of current activities can be suggestive of the near future. The authors envision that such behavioral insights can help deliver enhanced network services. While behavior-aware networking is a...

    Provided By Duke University

  • White Papers // May 2011

    A Hierarchical Model to Evaluate Quality of Experience of Online Services Hosted by Cloud Computing

    As online service providers utilize cloud computing to host their services, they are challenged by evaluating the quality of experience and designing redirection strategies in this complicated environment. The authors propose a hierarchical modeling approach that can easily combine all components of this environment. Identifying interactions among the components is...

    Provided By Duke University

  • White Papers // Aug 2009

    A Stochastic Model for Beaconless IEEE 802.15.4 MAC Operation

    IEEE 802.15.4 is a popular choice for MAC/PHY protocols in low power and low data rate wireless sensor networks. In this paper, the authors develop a stochastic model for the beaconless operation of IEEE 802.15.4 MAC protocol. Given the number of nodes competing for channel access and their packet generation...

    Provided By Duke University

  • White Papers // Jan 2011

    Managing Mixed-Use Clusters With Cluster-on-Demand

    Although clusters offer inexpensive computing power, they are difficult and expensive to manage, particularly for user communities with diverse software needs. This paper presents Cluster-On-Demand (COD), a cluster operating system framework for mixed-use clusters. COD interposes on standard network management services - DHCP, NIS, and DNS - to partition a...

    Provided By Duke University

  • White Papers // Jan 2011

    ConSil: Low-Cost Thermal Mapping of Data Centers

    Several projects involving high-level thermal management - such as eliminating "Hot spots" or reducing cooling costs through intelligent workload placement - require ambient air temperature readings at a fine granularity. Unfortunately, current thermal instrumentation methods involve installing a set of expensive hardware sensors. Modern motherboards include multiple on-board sensors, but...

    Provided By Duke University

  • White Papers // Jan 2011

    Dynamic Virtual Clusters in a Grid Site Manager

    This paper presents new mechanisms for dynamic resource management in a cluster manager called Cluster-On-Demand (COD). COD allocates servers from a common pool to multiple virtual clusters (vclusters), with independently configured software environments, name spaces, user access controls, and network storage volumes. The authors' present experiments using the popular Sun...

    Provided By Duke University

  • White Papers // Jan 2011

    Weatherman: Automated, Online, and Predictive Thermal Mapping and Management for Data Centers

    Recent advances have demonstrated the potential benefits of coordinated management of thermal load in data centers, including reduced cooling costs and improved resistance to cooling system failures. A key unresolved obstacle to the practical implementation of thermal load management is the ability to predict the effects of workload distribution and...

    Provided By Duke University

  • White Papers // Jan 2011

    Virtual Machine Hosting for Networked Clusters: Building the Foundations for "Autonomic" Orchestration

    Virtualization technology offers powerful resource management mechanisms, including performance-isolating resource schedulers, live migration, and suspend/resume. But how should networked virtual computing systems use these mechanisms? A grand challenge is to devise practical policies to drive these mechanisms in a self-managing or "Autonomic" system, without relying on human operators. This paper...

    Provided By Duke University

  • White Papers // Jan 2011

    Making Scheduling "Cool": Temperature-Aware Workload Placement in Data Centers

    Trends towards consolidation and higher-density computing configurations make the problem of heat management one of the critical challenges in emerging data centers. Conventional approaches to addressing this problem have focused at the facilities level to develop new cooling technologies or optimize the delivery of cooling. In contrast to these approaches,...

    Provided By Duke University

  • White Papers // Jan 2011

    Learning Application Models for Utility Resource Planning

    Shared computing utilities allocate compute, network, and storage resources to competing applications on demand. An awareness of the demands and behaviors of the hosted applications can help the system to manage its resources more effectively. This paper proposes an active learning approach that analyzes performance histories to build predictive models...

    Provided By Duke University

  • White Papers // Jan 2011

    Empirical Comparison of Techniques for Automated Failure Diagnosis

    Failures of Internet services and enterprise systems lead to user dissatisfaction and considerable loss of revenue. Manual diagnosis of these failures can be laborious, slow, and expensive. This problem has received considerable attention recently from researchers in systems, databases, machine learning and knowledge discovery, computer architecture, and other areas. The...

    Provided By Duke University