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Articles 271 - 300 of 370

Full-Text Articles in Electrical and Computer Engineering

A New Approach To Scalable Lindasystems Based On Swarms, Ronaldo Menezes, Robert Tolksdorf Mar 2003

A New Approach To Scalable Lindasystems Based On Swarms, Ronaldo Menezes, Robert Tolksdorf

Electrical Engineering and Computer Science Faculty Publications

Natural forming multi-agent systems (aka Swarms) have the ability to grow to enormous sizes without requiring any of the agents to oversee the entire system. The success of these systems comes from the fact that agents are simple and the interaction with the environment and neighboring agents is local in nature. In this paper we look at abstractions in the field of swarms and study their applicability in the context of coordination systems. In particular, we focus on the problematic issue of scalability of Linda systems. The purpose of this work is to look at abstractions yielded from observations of …

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Testing With Hostile Data Streams, Alan A. Jorgensen Jan 2003

Testing With Hostile Data Streams, Alan A. Jorgensen

Electrical Engineering and Computer Science Faculty Publications

This note describes a method of testing software for response to malicious data streams. Systems that process data streams obtained from an external source such as the Internet are vulnerable to security issues if malicious data is not processed correctly. This note describes a testing method that creates malicious data streams, applies them to a software application and checks the appropriateness of the application response. The note begins with a description of the problem: inadequate testing of software response to malicious data streams. I present a method of testing the response to malicious data streams and introduce the concepts of …

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An Analysis Of The 1999 Darpa/Lincoln Laboratory Evaluation Data For Network Anomaly Detection, Matthew V. Mahoney, Philip K. Chan Jan 2003

An Analysis Of The 1999 Darpa/Lincoln Laboratory Evaluation Data For Network Anomaly Detection, Matthew V. Mahoney, Philip K. Chan

Electrical Engineering and Computer Science Faculty Publications

We investigate potential simulation artifacts and their effects on the evaluation of network anomaly detection systems in the 1999 DARPA/MIT Lincoln Laboratory off-line intrusion detection evaluation data set. A statistical comparison of the simulated background and training traffic with real traffic collected from a university departmental server suggests the presence of artifacts that could allow a network anomaly detection system to detect some novel intrusions based on idiosyncrasies of the underlying implementation of the simulation, with an artificially low false alarm rate. The evaluation problem can be mitigated by mixing real traffic into the simulation. We compare five anomaly detection …

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Heat: Runtime Interception Of Win32 Functions, Michael M. Andrews Jan 2003

Heat: Runtime Interception Of Win32 Functions, Michael M. Andrews

Electrical Engineering and Computer Science Faculty Publications

When researching in any field, it is always important to build upon existing work. In most research disciplines, the core base is well defined and widely documented. However, the basis of innovative research in computer science, especially at the systems level, can often be proprietary information. This can be a major problem as unless you have source code available you must be granted access to the proprietary information (by usually signing non-disclosure documents) which comes with barriers on access, ownership and the ability to publish results. As an example, Microsoft's Windows operating system (all versions) can be a good base …

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Learning Rules For Anomaly Detection Of Hostile Network Traffic, Matthew V. Mahoney, Philip K. Chan Jan 2003

Learning Rules For Anomaly Detection Of Hostile Network Traffic, Matthew V. Mahoney, Philip K. Chan

Electrical Engineering and Computer Science Faculty Publications

We introduce an algorithm called LERAD that learns rules for finding rare events in nominal time-series data with long range dependencies. We use LERAD to find anomalies in network packets and TCP sessions to detect novel intrusions. LERAD outperforms the original participants in the 1999 DARPA/Lincoln Laboratory intrusion detection evaluation, and detected most attacks that eluded a firewall in a university departmental server environment.

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An Optimum Greedy Algorithm For Choosing Minimal Set Of Conflicting Constraints In The Point Sequencing Problem, Florent Launay, Mitra Debasis Dec 2002

An Optimum Greedy Algorithm For Choosing Minimal Set Of Conflicting Constraints In The Point Sequencing Problem, Florent Launay, Mitra Debasis

Electrical Engineering and Computer Science Faculty Publications

In this work, we first have proposed a technique to define the "causes" of inconsistency on an online point based reasoning constraint network. Second, we introduce an algorithm that proposes the user a minimal set of relations to remove when inconsistencies are detected. We have developed and implemented a battery of algorithms for the purpose of this type of reasoning. Some useful theorems and properties are defined for proving the 'minimal' aspect of the algorithm. Finally, we found that our investigation was a polynomially solvable sub problem of the vertex cover problem.

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Learning Implicit User Interest Hierarchy For Context In Personalization, Philip K. Chan, Hyoung-Rae Kim Oct 2002

Learning Implicit User Interest Hierarchy For Context In Personalization, Philip K. Chan, Hyoung-Rae Kim

Electrical Engineering and Computer Science Faculty Publications

To provide a more robust context for personalization, we desire to extract a continuum of general (long-term) to specific (short-term) interests of a user. Our proposed approach is to learn a user interest hierarchy (UIH) from a set of web pages visited by a user. We devise a divisive hierarchical clustering (DHC) algorithm to group words (topics) into a hierarchy where more general interests are represented by a larger set of words. Each web page can then be assigned to nodes in the hierarchy for further processing in learning and predicting interests. This approach is analogous to building a subject …

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An Algorithm Applicable To Clearing Combinatorial Exchanges, Marius Silaghi Sep 2002

An Algorithm Applicable To Clearing Combinatorial Exchanges, Marius Silaghi

Electrical Engineering and Computer Science Faculty Publications

It is important to approach negotiations in a way that ensures privacy. So far, research has focused on securely solving restricted classes of negotiation techniques, mainly the (M+1)-st-price auctions. Here we show how these results can be adapted to more general problems. This paper extends our previous results on how distributed finite discrete problems can be solved securely. Such problems can model larger classes of negotiation problems, .e.g. Combinatorial Exchanges [Sil02]. In Finite Discrete Maximization, each tuple in the problem space is associated with an integer value in a predefined interval and we search for a maximizing input. Values from …

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Network Traffic Anomaly Detection Based On Packet Bytes, Philip K. Chan, Matthew V. Mahoney Sep 2002

Network Traffic Anomaly Detection Based On Packet Bytes, Philip K. Chan, Matthew V. Mahoney

Electrical Engineering and Computer Science Faculty Publications

Hostile network traffic is often "different" from benign traffic in ways that can be distinguished without knowing the nature of the attack. We describe a two-stage anomaly detection system for identifying suspicious traffic. First, we filter traffic to pass only the packets of most interest, e.g., the first few packets of incoming server requests. Second, we model the most common protocols (IP, TCP, telnet, FTP, SMTP, HTTP) at the packet byte level to flag events (byte values) that have not been observed for a long time. This simple system detects 132 of 185 attacks in the 1999 DARPA IDS evaluation …

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Linear Feature Detection Using Multiresolution Wavelet Filters, Samuel Peter Kozaitis, Somkait Udomhunsakul, Rufus H. Cofer, A. Agarawal, Shuwu Song Aug 2002

Linear Feature Detection Using Multiresolution Wavelet Filters, Samuel Peter Kozaitis, Somkait Udomhunsakul, Rufus H. Cofer, A. Agarawal, Shuwu Song

Electrical Engineering and Computer Science Faculty Publications

We detected roads in aerial imagery based on multiresolution linear feature detection. Our method used the products of wavelet coefficients at several scales to identify and locate linear features. After detecting possible road pixels, we used a shortest-path algorithm to identify roads. The multiresolution approach effectively increased the size of the region we examined when looking for possible road pixels and reduced the effect of noise. We found that our approach leads to an effective method for detecting roads in aerial imagery.

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Unicode Compression: Does Size Really Matter?, Ryan Stansifer, Steve Atkin Jul 2002

Unicode Compression: Does Size Really Matter?, Ryan Stansifer, Steve Atkin

Electrical Engineering and Computer Science Faculty Publications

The Unicode standard provides several algorithms, techniques, and strategies for assigning, transmitting, and compressing Unicode characters. These techniques allow Unicode data to be represented in a concise format in several contexts. In this paper we examine several techniques and strategies for compressing Unicode data using the programs gzip and bzip. Unicode compression algorithms known as SCSU and BOCU are also examined. As far as size is concerned, algorithms designed specifically for Unicode may not be necessary.

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Probabilistic Microcell Prediction Model, Song-Kyoo Kim Jun 2002

Probabilistic Microcell Prediction Model, Song-Kyoo Kim

Electrical Engineering and Computer Science Faculty Publications

A microcell is a cell with 1-km or less radius which is suitable for heavily urbanized area such as a metropolitan city. This paper deals with the microcell prediction model of propagation loss which uses probabilistic techniques. The RSL (Receive Signal Level) is the factor which can evaluate the performance of a microcell and the LOS (Line-Of-Sight) component and the blockage loss directly effect on the RSL. We are combining the probabilistic method to get these performance factors. The mathematical methods include the CLT (Central Limit Theorem) and the SPC (Statistical Process Control) to get the parameters of the distribution. …

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Learning Nonstationary Models Of Normal Network Traffic For Detecting Novel Attacks, Philip K. Chan, Matthew V. Mahoney Apr 2002

Learning Nonstationary Models Of Normal Network Traffic For Detecting Novel Attacks, Philip K. Chan, Matthew V. Mahoney

Electrical Engineering and Computer Science Faculty Publications

Traditional intrusion detection systems (IDS) detect attacks by comparing current behavior to signatures of known attacks. One main drawback is the inability of detecting new attacks which do not have known signatures. In this paper we propose a learning algorithm that constructs models of normal behavior from attack-free network traffic. Behavior that deviates from the learned normal model signals possible novel attacks. Our IDS is unique in two respects. First, it is nonstationary, modeling probabilities based on the time since the last event rather than on average rate. This prevents alarm floods. Second, the IDS learns protocol vocabularies (at the …

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Genetic Routing Algorithms To Optimize Availability In Broadband Wireless Networks With Load Balancing, William S. Hortos Mar 2002

Genetic Routing Algorithms To Optimize Availability In Broadband Wireless Networks With Load Balancing, William S. Hortos

Electrical Engineering and Computer Science Faculty Publications

Packet-switched networks using the Internet Protocol (IP) provide multimedia services through broadband wireless access to mobile and fixed subscribers from an IP core network via bi-directional paths consisting of a hierarchy of high-speed routers, switches, and servers. Packets are aggregated at the nodes that form the ordered links of end-to-end paths between subscriber and gateway. Network resources are allocated at nodes to meet quality of service (QoS) requirements of new and existing calls. If sufficient resources are not available to satisfy a call's QoS, the call is blocked or dropped, reducing network "uptime" or availability. Packet flows are shared among …

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On The Use Of Linda As A Framework For Distributed Database Systems, Madhan M. Thirukonda, Ronaldo Menezes Feb 2002

On The Use Of Linda As A Framework For Distributed Database Systems, Madhan M. Thirukonda, Ronaldo Menezes

Electrical Engineering and Computer Science Faculty Publications

Linda is a coordination language capable of solving issues in distributed computing environments that relate to process synchronization, communication and creation. The expressiveness of Linda in distributed systems is such that researchers are proposing novel applications using Linda as a primary means of coordination. The examples range from peer-to-peer to groupware computing, from simple chat applications to control systems. Surprisingly, Linda has not been used in the field of distributed databases, although Linda can be helpful in solving coordination issues in a distributed database system. In this paper, we look at a possibility of using Linda in the context of …

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Webspy: An Architecture For Monitoring Web Server Availability In A Multi-Platform Environment, Madhan M. Thirukonda Jan 2002

Webspy: An Architecture For Monitoring Web Server Availability In A Multi-Platform Environment, Madhan M. Thirukonda

Electrical Engineering and Computer Science Faculty Publications

For an electronic business (e-business), customer satisfaction can be the difference between long-term success and short-term failure. Customer satisfaction is highly impacted by Web server availability, as customers expect a Web site to be available twenty-four hours a day and seven days a week. Unfortunately, unscheduled Web server downtime is often beyond the control of the organization. What is needed is an effective means of identifying and recovering from Web server downtime in order to minimize the negative impact on the customer. An automated architecture, called WebSpy, has been developed to notify administration and to take immediate action when Web …

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Testing Exception And Error Cases Using Runtime Fault Injection, James A. Whittaker, Florence E. Mottay, Ibrahim K. El-Far Dec 2001

Testing Exception And Error Cases Using Runtime Fault Injection, James A. Whittaker, Florence E. Mottay, Ibrahim K. El-Far

Electrical Engineering and Computer Science Faculty Publications

Fault injection deals with the insertion or simulation of faults in order to test the robustness and fault tolerance of a software application. Such measures are generally performed on software that is mission critical, to the extent that failure could have significant negative ramifications. Actual injection of faults can be performed either at compile time, when additional code is inserted to force error conditions to evaluate to true, or at runtime during which faults are injected into the software's execution environment. This paper focuses on the latter type of fault injection and presents a new mechanism for inserting environmental faults. …

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Survivable Mobile Operating System, James Whittaker, Mohommad Samarah Dec 2001

Survivable Mobile Operating System, James Whittaker, Mohommad Samarah

Electrical Engineering and Computer Science Faculty Publications

Although there is a large body of work on cryptographic techniques and algorithms that provide basic building blocks to solve specific security problems, relatively little work has been done in investigating security issues in mobile system contexts. Conventional security controls work well for static code, but break down with code mobility. In this paper, we investigate the need for end-to-end security in mobile and wireless operating systems. We study the implications of mobility - specifically, ways in which the operating system may facilitate communication security. We suggest a framework for designing security into mobile devices by building encryption into the …

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Phad: Packet Header Anomaly Detection For Identifying Hostile Network Traffic, Philip K. Chan, Matthew V. Mahoney Nov 2001

Phad: Packet Header Anomaly Detection For Identifying Hostile Network Traffic, Philip K. Chan, Matthew V. Mahoney

Electrical Engineering and Computer Science Faculty Publications

We describe an experimental packet header anomaly detector (PHAD) that learns the normal range of values for 33 fields of the Ethernet, IP, TCP, UDP, and ICMP protocols. On the 1999 DARPA off-line intrusion detection evaluation data set (Lippmann et al. 2000), PHAD detects 72 of 201 instances (29 of 59 types) of attacks, including all but 3 types that exploit the protocols examined, at a rate of 10 false alarms per day after training on 7 days of attack-free internal network traffic. In contrast to most other network intrusion detectors and firewalls, only 8 attacks (6 types) are detected …

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A Generalized Framework For Reasoning With Angular Directions, Mitra Debasis Nov 2001

A Generalized Framework For Reasoning With Angular Directions, Mitra Debasis

Electrical Engineering and Computer Science Faculty Publications

This extended abstract presents a new scheme for qualitative reasoning with directions between points in 2D-space, called Star-ontology(6). The current results of our study on the complexity issues for reasoning with incomplete/disjunctive information using this new ontology has been outlined here. We have also proposed a generalized framework Star-ontology(a) for an integer a, that could be specialized to many ontologies including some of the known ones like the 2D-Cradinal ontology for a=4, and the currently studied one for a=6. This generalization also points to an interesting direction for investigation in the field of spatio-temporal reasoning.

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Modeling And Test Of Pixel Cross-Talk In Hgcdte Focal Plane Arrays, Thomas J. Sanders, E. Lee Caraway, Glenn T. Hess, Gwendolyn W. Newsome, Theodore Fischer Oct 2001

Modeling And Test Of Pixel Cross-Talk In Hgcdte Focal Plane Arrays, Thomas J. Sanders, E. Lee Caraway, Glenn T. Hess, Gwendolyn W. Newsome, Theodore Fischer

Electrical Engineering and Computer Science Faculty Publications

Mercury Cadmium Telluride focal plane arrays with well over 1000 pixels have been fabricated for a number of years. These FPA's have been built as large two-dimensional arrays of HgCdTe p-n junction diodes on a single CdTe or CdZnTe substrate. Sensitivity of each pixel to impinging radiation is one of the most important quality factors for these devices. However, material parameters, which give diode high sensitivity, are the same as those that cause cross talk between adjacent diodes in the array. This cross talk causes a blurred image and in general is a detrimental factor for the FPA system. The …

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Detecting Novel Attacks By Identifying Anomalous Network Packet Headers, Philip K. Chan, Matthew V. Mahoney Oct 2001

Detecting Novel Attacks By Identifying Anomalous Network Packet Headers, Philip K. Chan, Matthew V. Mahoney

Electrical Engineering and Computer Science Faculty Publications

We describe a simple and efficient network intrusion detection algorithm that detects novel attacks by flagging anomalous field values in packet headers at the data link, network, and transport layers. In the 1999 DARPA off-line intrusion detection evaluation test set (Lippmann et. al. 2000), we detect 76% of probes and 48% of denial of service attacks (at 10 false alarms per day). When this system is merged with the 18 systems in the original evaluation, the average detection rate for attacks of all types increases from 61% to 65%. We investigate the effect on performance when attack free training data …

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Completeness Of Propositional Logic As A Program, Ryan Stansifer Oct 2001

Completeness Of Propositional Logic As A Program, Ryan Stansifer

Electrical Engineering and Computer Science Faculty Publications

The proof of completeness for propositional logic is a constructive one, so a computer program is suggested by the proof. We prove the completeness theorem for Łukasiewicz’ axioms directly, and translate the proof into the functional languages SML and Haskell. In this paper we consider this proof as a program. The program produces enormous proof trees, but it is, we contend, as good a proof of completeness as the standard mathematical proofs.The real value of the exercise is the further evidence it provides that typed, functional languages can clearly express the complex abstractions of mathematics.

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Optimization Of Real-Time Protocols For Wireless Packet-Switched Multimedia Networks Based On Partially Observed Multivariate Point Processes, William S. Hortos Aug 2001

Optimization Of Real-Time Protocols For Wireless Packet-Switched Multimedia Networks Based On Partially Observed Multivariate Point Processes, William S. Hortos

Electrical Engineering and Computer Science Faculty Publications

Next-generation wireless networks have been designed to transport integrated multimedia services based on a cellular extension of a packet-switched architecture using variants of the Internet protocol (IP). Each call, arriving to or active within the network, carries demand for one or more services in parallel, where each service type has a guaranteed quality of service (QoS). Admission of new calls to the wireless IP network (WIN) from the gateway of a wired network or from a mobile subscriber (MS) is allowed by call admission control (CAC) procedures. MS roaming among the nodes of the WIN is controlled by handoff procedures …

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Adaptive Threshold Selection Technique For Denoising In Dithered Quantizers, Samuel Peter Kozaitis, Hemen Goswami Mar 2001

Adaptive Threshold Selection Technique For Denoising In Dithered Quantizers, Samuel Peter Kozaitis, Hemen Goswami

Electrical Engineering and Computer Science Faculty Publications

We described an adaptive denoising method to improve image quality in a wavelet-based image compression process that uses dithered quantization. In our method, the second-order moment of the quantization noise is made independent of the signal by random quantization. Then, the quantization noise is reduced by thresholding wavelet coefficients. We first obtained a fixed threshold using any known technique. Then, a neighborhood is searched for the optimal threshold to optimize some cost function.

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Hybrid Evolutionary Computing Model For Mobile Agents Of Wireless Internet Multimedia, William S. Hortos Mar 2001

Hybrid Evolutionary Computing Model For Mobile Agents Of Wireless Internet Multimedia, William S. Hortos

Electrical Engineering and Computer Science Faculty Publications

The ecosystem is used as an evolutionary paradigm of natural laws for the distributed information retrieval via mobile agents to allow the computational load to be added to server nodes of wireless networks, while reducing the traffic on communication links. Based on the Food Web model, a set of computational rules of natural balance form the outer stage to control the evolution of mobile agents providing multimedia services with a wireless Internet protocol (WIP). The evolutionary model shows how mobile agents should behave with the WIP, in particular, how mobile agents can cooperate, compete and learn from each other, based …

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Enabling Mobile Agents Communication, Mohammad Samarah, Philip K. Chan Oct 2000

Enabling Mobile Agents Communication, Mohammad Samarah, Philip K. Chan

Electrical Engineering and Computer Science Faculty Publications

In this paper, we investigate the need for well-suited remote communication architectures to address communication issues in mobile agent environments. We study the implication of mobility for agent architectures – specifically, ways in which the architecture may facilitate agent communication. We present an architecture for inter-agent communication suitable for remote messaging, agent monitoring, agent tracing, and agent debugging for mobile agent environments. The architecture allows for the dynamic adaptation of communication components. It provides for a seamless and continuous active communication during the agent migration process. We have implemented an agent framework simulator that conforms to all these requirements. The …

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A Protocol Language Approach To Generating Client-Server Software, Philip K. Chan, Melvin A.L. Douglas Oct 2000

A Protocol Language Approach To Generating Client-Server Software, Philip K. Chan, Melvin A.L. Douglas

Electrical Engineering and Computer Science Faculty Publications

Client-server software is becoming more common as the Internet grows. To ease the burden of repeatedly writing low-level communication and protocol code, we seek to design a protocol language, My Simple Protocol Language (MSPL), that produces the corresponding communication functions. The programmer then supplies the rest of the application-specific code but never modifies the generated code. Besides saving development time, this approach also reduces programming errors. The potential to develop more efficient code also exists once the technique of generating code is mastered. The main contribution, however, is that unlike RPC, Corba or RMI, we provide the user with not …

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Multiresolution Gradient-Based Edge Detection In Noisy Images Using Wavelet Domain Filters, Yunwoo Lee, Samuel Peter Kozaitis Sep 2000

Multiresolution Gradient-Based Edge Detection In Noisy Images Using Wavelet Domain Filters, Yunwoo Lee, Samuel Peter Kozaitis

Electrical Engineering and Computer Science Faculty Publications

We detected edges in noisy images using multiresolution analysis with the wavelet transform. Products of wavelet coefficients at several scales were used to identify and locate edges. We found that it was important to consider the changes in edge position at different scales to detect edges in noisy imagery. We analyzed one-dimensional edges and compared the results of our approach with the first derivative of the signal. In addition, we compared the results of noisy images with another wavelet-based edge detection method. Our results led to improved edge detection in noisy images.

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Real-Time Performance Analysis Of Wireless Multimedia Networks Based On Partially Observed Multivariate Point Processes, William S. Hortos Jul 2000

Real-Time Performance Analysis Of Wireless Multimedia Networks Based On Partially Observed Multivariate Point Processes, William S. Hortos

Electrical Engineering and Computer Science Faculty Publications

Third-generation (3G) wireless networks will support integrated multimedia services based on a cellular extension of a packet-switched architecture using variants of the Internet protocol (IP). Services can be categorized as real-time and delaysensitive, or non-real-time and delay-insensitive. Each call, arriving to or active within the network, carries demand for one or more services in parallel; each service type with a guaranteed quality of service (QoS). Admission of new calls to the wireless IP network (WIN) from the gateway of a wired network or from a mobile subscriber (MS) is allowed by call admission control (CAC) procedures. Roaming of the MSs …

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