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A flash crowd is a surge in traffic to a particular Web site that causes the site to be virtually unreach-able. We present a theoretical model of flash crowd events and evaluate the performance of various multi-level caching techniques suitable for managing these events. Our results show that orders of magnitude savings can be achieved in client response(More)
The storage traffic for different Logical Units (LUs) of a disk array converge at the array's cache. The cache is allocated among the LUs approximately according to their relative I/O rates. In the case of non-uniform I/O rates and sensitivity to storage response times between differing applications in a Storage Area Network (SAN), undesirable cache(More)
Complex Event Processing (CEP) over event streams has become increasingly important for real-time applications ranging from healthcare to supply chain management. In such applications, arbitrarily complex sequence patterns as well as non existence of such complex situations must be detected in real time. To assure real-time responsiveness for detection of(More)
The gap between CPU speeds and the speed of the technologies providing the data is increasing. As a result, latency and bandwidth to needed data is limited by the performance of the storage devices and the networks that connect them to the CPU. Distributed caching techniques are often used to reduce the penalties associated with such caching; however, such(More)
We are constructing caching policies that have 13-20% lower miss rates than the best of twelve baseline policies over a large variety of request streams. This represents an improvement of 49–63% over Least Recently Used, the most commonly implemented policy. We achieve this not by designing a specific new policy but by using on-line Machine Learning(More)
In this paper, we describe the design of our architecture for Continuous, Heterogeneous Analysis Over Streams, aka CHAOS that combines stream processing, approximation techniques, mining, complex event processing and visualization. CHAOS, with the novel concept of Computational Stream Analysis Cube, provides an effective, scalable platform for near real(More)
—Sign Language, the natural communication medium for a deaf person, is difficult to learn for the general population. The prospective signer should learn specific hand gestures in coordination with head motion, facial expression and body posture. Since language learning can only advance with continuous practice and corrective feedback, we have developed an(More)
Ahstract-Complex event processing (CEP) over event streams has become increasingly important for real-time applications ranging from health care, supply chain management to busi­ ness intelligence. These monitoring applications submit complex queries to track sequences of events that match a given pattern. As these systems mature the need for increasingly(More)
Many modern applications, including online financial feeds, tag-based mass transit systems and RFID-based supply chain management systems transmit real-time data streams. There is a need for event stream processing technology to analyze this vast amount of sequential data to enable online operational decision making. Existing techniques such as traditional(More)
—In this project, we have developed a sign language tutor that lets users learn isolated signs by watching recorded videos and by trying the same signs. The system records the user's video and analyses it. If the sign is recognized, both verbal and animated feedback is given to the user. The system is able to recognize complex signs that involve both hand(More)