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Articles 571 - 600 of 666

Full-Text Articles in Computer Sciences

Game Theoretical Data Replication Techniques For Large-Scale Autonomous Distributed Computing Systems, Samee Ullah Khan Jul 2007

Game Theoretical Data Replication Techniques For Large-Scale Autonomous Distributed Computing Systems, Samee Ullah Khan

Computer Science and Engineering Dissertations - Archive

Data replication in geographically dispersed servers is an essential technique for reducing the user perceived access time in large-scale distributed computing systems. A majority of the conventional replica placement techniques lack scalability and solution quality. To counteract such issues, this thesis proposes a game theoretical replica placement framework, in which autonomous agents compete for the allocation or reallocation of replicas onto their representative servers in a self-managed fashion. Naturally, each agent's goal is to maximize its own benefit. However, the framework is designed to suppress individualism and to ensure system-wide optimization. Using this framework as an environment, several cooperative and …

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Sees - An Adaptive Multimodal User Interface For The Visually Impaired, Aparajit Saigal May 2007

Sees - An Adaptive Multimodal User Interface For The Visually Impaired, Aparajit Saigal

Computer Science and Engineering Theses - Archive

The enormous amount of electronic data present today can be a daunting task to access and process for a regular person, let alone someone with a disability. The World Wide Web and Electronic Mail have transformed the way we live. We are constantly become more dependent on this information, communication and commerce medium. The Speech Enabled Email System (SEES) is an alternate user interface that allows for the retrieval of emails and RSS feeds using speech. SEES can be accessed via a desktop application or through a telephony interface such as a regular phone-line or Voice over IP. This thesis …

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Automatic Content Analysis Of Endoscopy Video (Endoscopic Multimedia Information System), Sae K. Hwang May 2007

Automatic Content Analysis Of Endoscopy Video (Endoscopic Multimedia Information System), Sae K. Hwang

Computer Science and Engineering Dissertations - Archive

Advances in video technology are being incorporated into today's healthcare practice. For example, various types of endoscopes are used for colonoscopy, upper gastrointestinal endoscopy, enteroscopy, bronchoscopy, cystoscopy, laparoscopy, and some minimal invasive surgeries (i.e., video endoscopic neurosurgery). These endoscopes come in various sizes, but all have a tiny video camera at the tip of the endoscopes. During an endoscopic procedure, the tiny video camera generates a video signal of the interior of the human organ, for example, the internal mucosa of the colon. The video data are displayed on a monitor for real-time analysis by the physician. Diagnosis, biopsy and …

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Information Theoretic, Probabilistic And Maximum Partial Substructure Algorithms For Discovering Graph-Based Anomalies, William Fred Eberle May 2007

Information Theoretic, Probabilistic And Maximum Partial Substructure Algorithms For Discovering Graph-Based Anomalies, William Fred Eberle

Computer Science and Engineering Dissertations - Archive

The ability to mine data represented as a graph has become important in several domains for detecting various structural patterns. One important area of data mining is anomaly detection, particularly for fraud. However, less work has been done in terms of detecting anomalies in graph-based data. While there has been some previous work that has used statistical metrics and conditional entropy measurements, the results have been limited to certain types of anomalies and specific domains. In this work we present graph-based approaches to uncovering anomalies in domains where the anomalies consist of unexpected entity/relationship alterations that closely resemble non-anomalous behavior. …

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Flash Crowd Mitigation System, Dongchul Kim May 2007

Flash Crowd Mitigation System, Dongchul Kim

Computer Science and Engineering Theses - Archive

Flash crowd means that a web server suffers a sudden surge of traffic since a large number of Internet users access the web server simultaneously. Once a flash crowd occurs in a web server, the response rate for the HTTP requests decreases rapidly, or the web server may even crash. To protect the web server from such flash crowds, in this paper, we propose the Flash Crowd Mitigation System (FCMS) which is based on the cooperation of the web servers and the redirection of the HTTP request. In FCMS, when a flash crowd is predicted by the traffic monitoring module …

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Wildcat: An Integrated Stealth Environment For Dynamic Malware Analysis, Amit Vasudevan May 2007

Wildcat: An Integrated Stealth Environment For Dynamic Malware Analysis, Amit Vasudevan

Computer Science and Engineering Dissertations - Archive

Malware -- a term that refers to viruses, trojans, worms, spyware or any form of malicious code -- is widespread today. Given the devastating effects that malware have on the computing world, detecting and countering malware is an important goal. Malware analysis is a challenging and multi-step process providing insight into malware structure and functionality, facilitating the development of an antidote. To successfully detect and counter malware, malware analysts must be able to analyze them in binary, in both a coarse- (behavioral) and fine-grained (structural) fashion. However, current research in coarse- and fine-grained code analysis (categorized into static and dynamic) …

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Heros: A Patient-Centered Goal-Directed Electronic Medical Record System For The Homeless, Kallol Silas Mahata May 2007

Heros: A Patient-Centered Goal-Directed Electronic Medical Record System For The Homeless, Kallol Silas Mahata

Computer Science and Engineering Theses - Archive

Homelessness is a growing problem in the United States. Numerous barriers keep the street homeless from obtaining healthcare. Medical Street Outreach (MSO) programs are designed to reach out to the homeless. Gathering relevant clinical information on the streets is difficult, and carrying paper records in MSO is cumbersome and inefficient. Several complex healthcare record systems have been developed for hospitals, but no such system exists for collecting health data on the streets. In this thesis, we describe a light weight Electronic Medical Record (EMR), called HEROS (Homeless Electronic RecOrd System) that we have built to address the process of healthcare …

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Medical Decision Support System Using Augmentable Guideline Engine, Adetayo Afolabi Aiyedun May 2007

Medical Decision Support System Using Augmentable Guideline Engine, Adetayo Afolabi Aiyedun

Computer Science and Engineering Theses - Archive

Increasing life expectancy accompanied by existing growth of wireless infrastructure and ubiquitous computing technologies has given healthcare providers access to vital information within their healthcare networks. Medical decision support systems (MDSS) play an increasingly important role in medical practice by assisting physicians with making clinical decisions. MDSS are interactive computer programs, which are designed to assist physicians and other health professionals with decision making. Currently, the strategies for providing MDSS has failed, in part, because they have not provided a secure, timely access to information that is current, ability to modify their knowledge base without hard coding them in their …

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Efficient Multi-View Video Coding Scheme Based On Dynamic Video Object Segmentation, Xiaohui Wei May 2007

Efficient Multi-View Video Coding Scheme Based On Dynamic Video Object Segmentation, Xiaohui Wei

Computer Science and Engineering Dissertations - Archive

Multi-view video, which simultaneously acquires multiple video sequences from multiple viewpoints or view directions, is poised to become the next generation video technology. Exploiting redundancy is the hallmark of traditional video coding but is even more essential in multi-view video coding (MVC) where the data size is extremely large. The exploitation of additional redundancies, however, incurs extra computational overhead, thereby counteracting the benefits gained from coding efficiency. This dissertation proposes an efficient MVC scheme that provides a complete encoding solution with low complexity. This includes exploitation of inter- and intra-view redundancies for achieving high coding efficiency, and exploitation of inter-view …

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Efficient Visualization Of Streaming Sensor Network Data Using Approximation Technique, Sunil Pai May 2007

Efficient Visualization Of Streaming Sensor Network Data Using Approximation Technique, Sunil Pai

Computer Science and Engineering Theses - Archive

By commanding a large number of wireless sensor nodes capable of sensing, communicating, and computing, wireless sensor networks have revealed their vast potential in a plethora of applications. However, due to the stringent resources limitations on each sensor node ranging from energy and computation to network bandwidth and storage, efficient and light weight systems must be designed in order to accommodate the resource limited environment. Furthermore, due to the potentially large number of sensor nodes deployed, the amount of sensory data gathered therein can be overwhelming for processing and visualizing in a resource limited central controller, such as mobile devices. …

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Hiearchical Overlay For Service Composition In Pervasive Environments, Aparna Kailas May 2007

Hiearchical Overlay For Service Composition In Pervasive Environments, Aparna Kailas

Computer Science and Engineering Theses - Archive

The objective of pervasive computing is to allow users to perform their tasks in a transparent way regardless of device features. Resources on devices should be exploited to provide services in order to perform user tasks. When there is no exact match for the user task in the environment, the capabilities of available devices should be combined to perform the user task. Seamless Service Composition (SeSCo) abstracts device capabilities as services and leverages existing work on graph algorithms to perform service composition. A lightweight framework, PerSON (Service Overlay Network for Pervasive Environments) was developed to provide a service overlay network …

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A Dynamic Framework For Testing The Synchronization Behavior Of Java Monitors, Andres Yanes May 2007

A Dynamic Framework For Testing The Synchronization Behavior Of Java Monitors, Andres Yanes

Computer Science and Engineering Theses - Archive

A Java monitor is a specialized class that is used to synchronize the behavior of threads in a Java program. The monitors in a Java program must be adequately tested to ensure the correctness of the program. In this thesis we propose a dynamic framework in which a Java monitor is tested by exploring its state space in a depth-first manner. The state exploration procedure consists of dynamically creating method sequences to exercise the possible synchronization behavior of the monitor. During exploration, new threads will be created on the fly to simulate different scenarios that result from threads reaching the …

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Computing Best Coverage Path In The Presence Of Obstacles In Wireless Sensor Networks, Senjuti Basu Roy Apr 2007

Computing Best Coverage Path In The Presence Of Obstacles In Wireless Sensor Networks, Senjuti Basu Roy

Computer Science and Engineering Theses - Archive

Given a set S = {S1,...,Sn} of n homogeneous wireless sensors deployed in a two dimensional area, a source point s and a destination point t, the least protected point p along a path (s,t) is that point such that the Euclidean distance between p and its closest sensor node Si is maximum. This distance between p and S_{i} is called the Cover value of the path P(s,t). The Best Coverage Path between s and t, denoted as BCP(s,t), is the path that has the minimum cover value. Although there exists efficient algorithms to compute BCP in O(n log n) …

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A Random Walk Approach To Sampling Hidden Databases, Arjun Dasgupta Apr 2007

A Random Walk Approach To Sampling Hidden Databases, Arjun Dasgupta

Computer Science and Engineering Theses - Archive

A large part of the data on the World Wide Web is hidden behind form-like interfaces. These interfaces interact with a hidden back-end database to provide answers to user queries. Generating a uniform random sample of this hidden database by using only the publicly available interface gives us access to the underlying data distribution. In this thesis, we propose a random walk scheme over the query space provided by the interface to sample such databases. We discuss variants where the query space is visualized as a fixed and random ordering of attributes. We also propose techniques to further improve the …

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Inference Of Node And Edge Replacement Graph Grammars, Jacek Kukluk Feb 2007

Inference Of Node And Edge Replacement Graph Grammars, Jacek Kukluk

Computer Science and Engineering Dissertations - Archive

In this dissertation we study the inference of node and edge replacement graph grammars. The approach is based on previous research in frequent isomorphic subgraphs discovery. We extend the search for frequent subgraphs by checking for overlap among the instances of the subgraphs in the input graph. If subgraphs overlap by one node, we propose a node replacement graph grammar production. If subgraphs overlap by two nodes or two nodes and an edge, we propose an edge replacement graph grammar production. We also can infer a hierarchy of productions by compressing portions of a graph described by a production and …

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Tracing And Replay Of Real-Time Concurrent Programs In Vxworks, Daxa Keshavji Patel Dec 2006

Tracing And Replay Of Real-Time Concurrent Programs In Vxworks, Daxa Keshavji Patel

Computer Science and Engineering Theses - Archive

Real-time concurrent programs are difficult to analyze, debug and test because of the existence of race conditions. In particular, cyclic debugging requires the ability to reproduce a failed execution. That is, when a failure is observed during a test run, it is often necessary to reproduce the test run as an effort to locate the bug that has caused the failure. However because of the variations in thread scheduling and signal latency, a real-time concurrent execution may not be reproduced simply by re-executing the program under test. In this thesis, we describe a language-based framework for tracing and replay of …

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Performance Analysis Of The Beacon Period Contraction Mechanism In Wimedia Mac For Uwb, Shenjin Sun Dec 2006

Performance Analysis Of The Beacon Period Contraction Mechanism In Wimedia Mac For Uwb, Shenjin Sun

Computer Science and Engineering Theses - Archive

The WiMedia MAC for UWB based WPANs is currently preferred among standards for wireless network since it requires non-infrastructure for ad hoc network, and also supports for Quality of Service (QoS). Without infrastructure, coordination of devices within radio range is achieved by the exchange of beacon frames, which is an overhead in WiMedia MAC, since no data transmission is allowed during Beacon Period (BP). In a dynamic network, devices might leave or join in, so beacon slots will be released or reoccupied with the changing of network. And BP contraction mechanism is aimed at reusing the released beacon slots in …

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Probabilistic Localization Of Mobile Ad Hoc Networks, Rui Huang Dec 2006

Probabilistic Localization Of Mobile Ad Hoc Networks, Rui Huang

Computer Science and Engineering Dissertations - Archive

The mobile ad hoc network localization problem deals with estimating the physical location of the nodes that do not have a direct way (e.g., GPS) to determine their own locations. Being an enabling technology that is considered essential to the success of the future implementation of ad hoc networks in the real world, localization is a fundamental problem that needs to be solved with the best possible accuracy and efficiency. For this research, we study the localization problem in its various incarnations such as localization through static beacons, mobile beacons, dynamically deployed beacons and link longevity estimation based on relative …

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Runtime Optimization And Load Shedding In Mavstream: Design And Implementation, Balakumar Kendai Dec 2006

Runtime Optimization And Load Shedding In Mavstream: Design And Implementation, Balakumar Kendai

Computer Science and Engineering Theses - Archive

In data stream processing systems Quality of Service (or QoS) is extremely important. The system should try its best to meet the QoS requirements specified by a user. On account of this difference, unlike in a database management system, a query cannot be optimized once and executed. It has been shown that different scheduling strategies are useful in trading tuple latency requirements with memory and throughput requirements. In addition, data stream processing systems may experience significant fluctuations in input rates. In order to meet the QoS requirements of data stream processing, a runtime optimizer equipped with several scheduling and load …

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Compensation Of Photobleached Images For A Cell Dynamics System, Sowmya Gopinath Dec 2006

Compensation Of Photobleached Images For A Cell Dynamics System, Sowmya Gopinath

Computer Science and Engineering Theses - Archive

Progress in the field of medicine attributes to the discoveries in biology that require an extensive knowledge of cell dynamics. Intracellular Cell Dynamics Analysis System (ICellDAS) is a web based tool aimed at automating sub cellular particle motion estimation, tracking and mobility analysis. The purpose of this tool is to develop a better understanding of specific biology problems by visualizing biological data. For reliable analysis as well as visualization of cell dynamics, it is essential that the acquired images reflect the exact information of the specimen. The goal of the thesis is to design an interface for the ICellDAS project …

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Analyzing Differences In Color Variation Sensitivity Between Experts And Novices To Find A Differentiating Process In Pigmented Skin Lesion Diagnosis, Yu-Chin Chai Dec 2006

Analyzing Differences In Color Variation Sensitivity Between Experts And Novices To Find A Differentiating Process In Pigmented Skin Lesion Diagnosis, Yu-Chin Chai

Computer Science and Engineering Theses - Archive

Fatal skin lesions such as melanomas appear as having high color variation to experts but often as having low variation to novices. This thesis investigated if it is possible to find a function representing an expert's color variation sensitivity to skin lesions without explicitly requiring them to provide a diagnosis. Various pigmented skin images with either normal pigmentation or with diseased lesions were evaluated by experts and novices. To determine the best color space for lesion differentiation, an optimization process based on parametric color dimensions in a RGB color space was used to find the parameters of a color transformation …

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Using Part Of Speech Structure Of Text In The Prediction Of Its Readability, Jagadeesh Kondru Dec 2006

Using Part Of Speech Structure Of Text In The Prediction Of Its Readability, Jagadeesh Kondru

Computer Science and Engineering Theses - Archive

Readability formulas predict the reading difficulty associated with text. They typically output a U.S. school grade level that indicates the reading ability required of a person in order for him to comprehend that text. Ability to predict text readability is useful because it helps educators select appropriate texts for students and authors write texts accessible to the audience they target. Existing readability formulas are based on countable aspects of the text such as average sentence length and average word length. We propose a new readability formula, the Readability Index, which is based on the part-of-speech structure of sentences in a …

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Complementing Current Active Queue Management Schemes With Rechoke And Receiver-Window Modification (Rwm), Visvasuresh Govindaswamy Dec 2006

Complementing Current Active Queue Management Schemes With Rechoke And Receiver-Window Modification (Rwm), Visvasuresh Govindaswamy

Computer Science and Engineering Dissertations - Archive

Explicit Congestion Notification (ECN) and Active Queue Management (AQM) schemes have been proposed for present-day TCP/IP networks to better manage network congestion. ECN enabled AQMs were shown to have a promising advantage over existing drop-tail queues. However, when implemented, they were susceptible to the following problems: 1) the timeout mechanism or the duration of the reception of three duplicate acknowledgements (ACKs), due to early-dropped packets by these AQMs, delays the response time of TCP (in reducing the offered rate) 2) using ECN with these AQMs has its downsides: i) its messages may get delayed or dropped due to congestion in …

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Ca-Ole- A Collaborative And Adaptive Online Learning Environment, Paola Gomez Dec 2006

Ca-Ole- A Collaborative And Adaptive Online Learning Environment, Paola Gomez

Computer Science and Engineering Theses - Archive

Demand for online learning environments has grown in the past few years, and schools have been offering more distance courses to their students. Designing adequate online learning environments is considerably more challenging than conventional Face-To-Face courses; therefore traditional methods can not be used. This thesis proposes the creation of a Collaborative and Adaptive Online Learning Environment (CA-OLE) that provides a structure where instructors can combine their lesson materials with an adaptive system and collaborative tools. CA-OLE innovative approach consists of an adaptive framework that changes the way the learning materials prepared by instructors are presented to the students depending on …

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Personalizing (Re-Ranking) Web Search Results Using Information Present On A Social Network, Sushruth Puttaswamy Dec 2006

Personalizing (Re-Ranking) Web Search Results Using Information Present On A Social Network, Sushruth Puttaswamy

Computer Science and Engineering Theses - Archive

We describe a social search engine paradigm which can be built on top of a classic search engine (e.g. Google, Yahoo, etc.) and a social information network (such as FriendSter). In this thesis, the objective was to design algorithms and develop methods to efficiently combine information available in the underlying systems (Search Engine & Social Information Network) to better satisfy the search needs of a user. We are interested on how to efficiently employ social information to re-order a list of URLs retrieved by querying a search engine. The objective was to re-order the list of URLs in a way …

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Adaptive Load Balancing And Change Visualization For Webvigil, Subramanian Chelladurai Hari Hara Dec 2006

Adaptive Load Balancing And Change Visualization For Webvigil, Subramanian Chelladurai Hari Hara

Computer Science and Engineering Theses - Archive

There is a need for selective monitoring, the contents of web pages. Periodical visit for understanding changes to a web page is both inefficient and time consuming. WebVigiL is a system developed for automating the change detection and timely notification of HTML/XML pages based on user specified changes of interest. User interest, specified as a sentinel/profile, is automatically monitored by the system using a combination of learning-based and event-driven techniques. The first prototype concentrated on the functionality of the WebVigiL system. This thesis extends the WebVigiL system in a number of ways. The primary focus of this thesis is the …

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Efficient Main Memory Algorithms For Significant Interval And Frequent Episode Discovery, Sagar Hasmukh Savla Dec 2006

Efficient Main Memory Algorithms For Significant Interval And Frequent Episode Discovery, Sagar Hasmukh Savla

Computer Science and Engineering Theses - Archive

There is a considerable research on sequential mining of time-series data. Sensor-based applications such as MavHome require prediction of events for automating the environment using time-series data collected over a period of time. In these applications, it is important to predict tight and accurate intervals of interest to effectively automate the application. Also, detection of frequent patterns is needed for the automation of sequence of happenings. Although, there is a considerable body of work on sequential mining of transactional data, most of them deal with time point data and make several iterations over the entire data set for discovering frequently …

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Automated Software Testing Using Covering Arrays, Chinmay P. Jayaswal Dec 2006

Automated Software Testing Using Covering Arrays, Chinmay P. Jayaswal

Computer Science and Engineering Theses - Archive

Modern society is increasingly dependent on the quality of software systems. Software testing is a widely used approach to ensure software quality. Since exhaustive testing is impractical due to resource constraints, it is necessary to strike a balance between test efforts and quality assurance. Interaction testing is one approach to marrying these two qualities. It characterizes the system under test by a set of parameters and the respective test values (domain size) for each parameter. Instead of testing all possible combinations of values for all the parameters, interaction testing constructs a covering array as a test set to cover all …

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End-To-End Optimal Algorithms For Traffic Engineering, Failure Detection And Recovery In Connectionless Networks, Sukruth Srikantha Dec 2006

End-To-End Optimal Algorithms For Traffic Engineering, Failure Detection And Recovery In Connectionless Networks, Sukruth Srikantha

Computer Science and Engineering Theses - Archive

In this thesis we propose a novel scheme to achieve intra-domain Traffic Engineering (TE), Failure Detection and Recovery (FR) in connectionless networks. This scheme addresses rate adaptation, load balancing and stability issues of the OSPF protocol namely, network convergence times and route flapping. With the current default settings of the OSPF parameters, the network takes several tens of seconds to recover from a failure. The main component in this delay is the time required to detect the failure using the Hello protocol. Route flap is another undesirable phenomenon and needs to be eliminated to achieve greater stability and robustness in …

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Evading Existing Stepping Stone Detection Methods Using Buffering, Madhu Venkateshaiah Dec 2006

Evading Existing Stepping Stone Detection Methods Using Buffering, Madhu Venkateshaiah

Computer Science and Engineering Theses - Archive

To gain anonymity and complicate their apprehension, attackers launch attacks not from their own systems but from previously compromised systems called stepping stones. An effective way to detect stepping stones is by comparing of incoming and outgoing connections in a network to find correlations. For the sake of simplicity, earlier approaches ignore that an attacker can add chaff to a traffic stream. But in reality, the attacker may be able to modify applications to use cover traffic. We loosen some assumptions made by earlier researchers and propose a simple buffering technique that could be used by an attacker to evade …

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