35883623
Supporting organizational knowledge management with agents
Organizations are looking at ways to manage their information resources. Both the capture and the use of data created by the organization have come under scrutiny. Part of the concern comes from their desire to enhance the business process and part comes from the explosion of data available to any organization. In this context, the role of committees is being examined both as consumers and producers of information. The present work is focused on making the vast amount of unstructured text more useful to committees. An agent environment has been designed and implemented.
271858
Providing scalable on-demand video services for heterogeneous receivers
To provide scalable video-on-demand services, precious system bandwidth must be shared among video requests. Although many efficient bandwidth-sharing techniques have been proposed, they are all designed for homogeneous receivers, i.e., the clients are assumed to have the same receiving bandwidth. For networks with client heterogeneity, these techniques either cannot work or have to compromise their performance. In this paper, we address this problem and propose an efficient solution allowing each client to use its whole receiving bandwidth to download data. To serve a client, the server first selects a set of serving channels for the client according to its actual receiving bandwidth. The video data needed for this client are then scheduled and dynamically adjusted for delivery over these channels. We evaluate the performance of the new technique using simulation and compare it with an existing scheme. Our study shows that by effectively leveraging client heterogeneity, the new technique achieves significantly smaller service latency
17046491
Lightweight agents for intrusion detection
We have designed and implemented an intrusion detection system (IDS) prototype based on mobile agents. Our agents travel between monitored systems in a network of distributed systems, obtain information from data cleaning agents, classify and correlate information, and report the information to a user interface and database via mediators.Agent systems with lightweight agent support allow runtime addition of new capabilities to agents. We describe the design of our Multi-agent IDS and show how lightweight agent capabilities allowed us to add communication and collaboration capabilities to the mobile agents in our IDS.
8229875
A Reputation-based Trust Management in Peer-to-Peer Network Systems
Peer-to-peer networks have gained a lot of attention over the last couple of years, mainly due to the popularity of the free multimedia file-sharing program Napster and a legal battle around it. Being open by nature P2P systems represent an ideal environment for various types of malicious intrusions. The problem of securing hosts on P2P network while keeping the openness of the system has been studied extensively over last couple of years but still remains open. Existing solutions based on reputation management either employ centralized algorithms or rely on peers' cooperation on the network. We describe a fully decentralized approach that allows computing peers' reputation based on the traffic between a node and its peers, independently of these peers willingness to cooperate in calculation of their reputation. 1 INTRODUCTION Peer-to-peer (P2P) network systems are increasingly gaining popularity on the Internet. These networks allow individual hosts (peers) to share and distribute various types of information over the Internet. By their nature, P2P networks are structured in a way that allows an open and unsupervised communication between peers. Therefore, these systems are vulnerable to various types of attacks, among which are denial-of-service attacks (DoS) and distribution of viruses. To protect themselves from malicious intentions, hosts should be able to identify reliable peers for communication. Identifying these peers is a challenging task in highly dynamic network environments like P2P networks. In this paper we suggest a solution to this problem based on the notion of trust. We propose a policy for managing traffic in peer-to-peer network based on peers' reputation. We also describe a model for computing this reputation using the trust score based on the peers' interaction with each other. Unlike most existing reputation-based models, our approach does not employ a centralized storage and only produces reputation scores on demand. The proposed solution is fully distributed and does not require any cooperation from the rest of the network. Our model aims to help users to select the most reliable peers whose past behavior shows willingness to participate in a proper functioning of the P2P system and at the same time to anticipate possible attacks from malicious peers by limiting their access to the victim peer's resources. In this paper we focus on a particular type of P2P systems, called Gnutella, which proved to be one of the most popular P2P systems. Furthermore, unlike other popular P2P applications such as KaZaa, the source …
5097434
Automated discovery of concise predictive rules for intrusion detection
This paper details an essential component of a multi-agent distributed knowledge network system for intrusion detection. We describe a distributed intrusion detection architecture, complete with a data warehouse and mobile and stationary agents for distributed problem-solving to facilitate building, monitoring, and analyzing global, spatio-temporal views of intrusions on large distributed systems. An agent for the intrusion detection system, which uses a machine learning approach to automated discovery of concise rules from system call traces, is described.We use a feature vector representation to describe the system calls executed by privileged processes. The feature vectors are labeled as good or bad depending on whether or not they were executed during an observed attack. A rule learning algorithm is then used to induce rules that can be used to monitor the system and detect potential intrusions. We study the performance of the rule learning algorithm on this task with and without feature subset selection using a genetic algorithm. Feature subset selection is shown to significantly reduce the number of features used while improving the accuracy of predictions.
14407932
Automatic measurement of quality metrics for colonoscopy videos
Colonoscopy is the accepted screening method for detection of colorectal cancer or its precursor lesions, colorectal polyps. Indeed, colonoscopy has contributed to a decline in the number of colorectal cancer related deaths. However, not all cancers or large polyps are detected at the time of colonoscopy, and methods to investigate why this occurs are needed. We present a new computer-based method that allows automated measurement of a number of metrics that likely reflect the quality of the colonoscopic procedure. The method is based on analysis of a digitized video file created during colonoscopy, and produces information regarding insertion time, withdrawal time, images at the time of maximal intubation, the time and ratio of clear versus blurred or non-informative images, and a first estimate of effort performed by the endoscopist. As these metrics can be obtained automatically, our method allows future quality control in the day-to-day medical practice setting on a large scale. In addition, our method can be adapted to other healthcare procedures. Last but not least, our method may be useful to assess progress during colonoscopy training, or as part of endoscopic skills assessment evaluations.
1948833
Synchronization of Distributed Simulation Using Broadcast Algorithms
Abstract Simulation, particularly of networks of queues, is an application with a high degree of inherent parallelism, and is of considerable practical interest. We continue the analysis of synchronization methods for distributed simulation, defined by the taxonomy in our previous paper. Specifically, we develop algorithms for time-driven simulation using a network of processors. For most of the synchronization methods considered, each node k of an n-node network simulation cannot proceed directly with its part of a simulation. Rather, it must compute some function Bk(ν1, ν2, …, νn), where νi is some value which must be obtained from node i. The value of νi at each node changes as the simulation progresses, and must be broadcast to every other node for the recomputation of the B-functions. In some cases, it is advantageous to compute the B-function in a distributed manner. Broadcast algorithms for such distributed computation are presented. Since the performance of a broadcast algorithm depends on the properties of the inter-process communication facility, we characterize some particular cases and give algorithms for each of them.
2722356
Forensic engineering techniques for VLSI CAD tools
The proliferation of the Internet has affected the business model of almost all semiconductor and VLSI CAD companies that rely on intellectual property (IP) as their main source of revenues. The fact that IP has become more accessible and easily transferable, has influenced the emergence of copyright infringement as one of the most common obstructions to e-commerce of IP.
In this paper, we propose a generic forensic engineering technique that addresses a number of copyright infringement scenarios. Given a solution <italic>S<subscrpt>P</subscrpt></italic> to a particular optimization problem instance <italic>P</italic> and a finite set of algorithms <italic>A</italic> applicable to <italic>P</italic>, the goal is to identify with a certain degree of confidence the algorithm <italic>A<subscrpt>i</subscrpt></italic> which has been applied to <italic>P</italic> in order to obtain <italic>S<subscrpt>P</subscrpt></italic>. We have applied forensic analysis principles to two problem instances commonly encountered in VLSI CAD: graph coloring and boolean satisfiability. We have demonstrated that solutions produced by strategically different algorithms can be associated with their corresponding algorithms with high accuracy.
33903019
The Design of Teletext Broadcast Cycles
Abstract Teletext is a one-way picture information system where pages of information are broadcast to all users in a continuous manner. System response time is an important consideration in designing teletext systems. Factors contributing to system response time include transmission speeds, amount of processing required at user terminals, and efficiency of picture encoding procedures. As important is the design of the teletext broadcast cycle, i.e., the order of pages to be broadcast in a cyclic manner. In this paper, we first derive a formula for the mean response time of a given cycle and a lower bound for the mean response time for any cycle. Next we present a design procedure that yields a cycle with mean response time close to the theoretical lower bound. The use of the results of this paper is demonstrated through a numerical example.
926253
Power minimization in QoS sensitive systems
The majority of modern multimedia and mobile systems have two common denominators: quality-of-service (QoS) requirements, such as latency and synchronization, and strict energy constraints. However, until now no synthesis techniques have been proposed for the design and efficient use of such systems. We have two main objectives: conceptual and synthesis. The conceptual objective is to develop a generic practical technique for the automatic development of online adaptive algorithms from efficient off-line algorithms using statistical techniques. The synthesis objective is to introduce the first design technique for QoS low-power synthesis. We introduce a system of provably-optimal techniques that minimize energy consumption of stream-oriented applications under two main QoS metrics: latency and synchronization. Specifically, we study how multiple voltages can be used to simultaneously satisfy hardware constraints and minimize power consumption while preserving the requested level of QoS. The purpose of the off-line algorithm is threefold. First, it is used as input to statistical software which is used to identify important and relevant parameters of the processes. Second, the algorithm provides buffer occupancy rate indicators. Lastly, it provides a way to combine buffer occupancy and QoS metrics to form a fast and efficient online algorithm. The effectiveness of the algorithms is demonstrated on a number of standard multimedia benchmarks.
30604687
A Comparative Study of Some Two-Processor Organizations
In many applications, parallelism inherent in a computation can be exploited by using a parallel computer organization. Such organizations may suffer throughput degradation because of data dependencies. The case of no data dependencies is considered. In this case, the throughput realized is dependent on the actual manner in which the parallel computer system is organized. A comparative performance study of four models of two-processor organizations is presented. The performance evaluation is through queueing analysis or simulation, the aim being to compare their response times under different workloads. This study also indicates the possibility of switching between alternate organizations in a dynamically reconfigurable system.