6847194
Analyzing the secure overlay services architecture under intelligent DDoS attacks
Distributed denial of service (DDoS) attacks are currently major threats to communication in the Internet. A secure overlay services (SOS) architecture has been proposed to provide reliable communication between clients and a target under DDoS attacks. The SOS architecture employs a set of overlay nodes arranged in three hierarchical layers that controls access to the target. Although the architecture is novel and works well under simple congestion based attacks, we observe that it is vulnerable under more intelligent attacks. We generalize the SOS architecture by introducing more flexibility in layering to the original architecture. We define two intelligent DDoS attack models and develop an analytical approach to study the impacts of the number of layers, number of neighbors per node and the node distribution per layer on the system performance under these two attack models. Our data clearly demonstrate that performance is indeed sensitive to the design features and the different design features interact with each other to impact overall system performance.
15576082
Real-time component-based systems
Component technology has become a central focus of software engineering in research and development. Reusability is a key factor that contributes to its success. The reuse of components can lead to a shortening of software development cycles and savings in software development costs. However, existing component models provide no support for real-time services and some real-time extensions of component models lack of consideration for reusability of components in providing real-time services. In this work, we develop a real-time component-based system that maintains the reusability of components.
5741503
A new scheme on privacy-preserving data classification
We address privacy-preserving classification problem in a distributed system. Randomization has been the approach proposed to preserve privacy in such scenario. However, this approach is now proven to be insecure as it has been discovered that some privacy intrusion techniques can be used to reconstruct private information from the randomized data tuples. We introduce an algebraic-technique-based scheme. Compared to the randomization approach, our new scheme can build classifiers more accurately but disclose less private information. Furthermore, our new scheme can be readily integrated as a middleware with existing systems.
35665703
Implementation of QoS-Provisioning system for voice over IP
In this paper, we address issues related to implementing Voice-over-IP (VoIP) services in packet switching networks. VoIP has been identified as a critical real-time application in the network QoS research community and has been implemented in commercial products. To provide competent quality of service for VoIP, the call admission control (CAC) mechanism has to be introduced to prevent packet losing and over-queuing. Several well-designed CAC mechanisms, such as the Site- Utilization-Based CAC and the link-utilization-based CAC mechanisms, are in place. However, the existing commercial VoIP systems have not been able to adequately apply and support these CAC mechanisms, and hence unable to provide QoS guarantees to VoIP. We have designed and implemented a QoS-Provisioning system that can be seamlessly integrated to the existing VoIP system to overcome its weakness in offering QoS guarantees. As a result, our system has been realized at Internet2 Voice Over IP Testbed in Texas A&M University.
6827646
Design and implementation of QoS-provisioning system for voice over IP
In this paper, we address issues in implementing voice over IP (VoIP) services in packet switching networks. VoIP has been identified as a critical real-time application in the network QoS research community and has been implemented in commercial products. To provide competent quality of service for VoIP systems comparable to traditional PSTN systems, a call admission control (CAC) mechanism has to be introduced to prevent packet loss and over-queuing. Several well-designed CAC mechanisms, such as the site-utilization-based CAC-and the link-utilization-based CAC mechanisms have been in place. However, the existing commercial VoIP systems have not been able to adequately apply and support these CAC mechanisms and, hence, have been unable to provide QoS guarantees to voice over IP networks. We have designed and implemented a QoS-provisioning system that can be seamlessly integrated with the existing VoIP systems to overcome their weakness in offering QoS guarantees. A practical implementation of our QoS-provisioning system has been realized.
8639082
Delay Analysis in Temperature-Constrained Hard Real-Time Systems with General Task Arrivals
In this paper, we study temperature-constrained hard real-time systems, where real-time guarantees must be met without exceeding safe temperature levels within the processor. Dynamic speed scaling is one of the major techniques to manage power so as to maintain safe temperature levels. As example, we adopt a simple reactive speed control technique in our work. We design a methodology to perform delay analysis for general task arrivals under reactive speed control with first-in-first-out (FIFO) scheduling and static-priority (SP) scheduling. As a special case, we obtain a close-form delay formula for the leaky-bucket task arrival model. Our data show how simple reactive speed control can decrease the delay of tasks compared with any constant-speed scheme
18781726
Watermarking scheme capable of resisting attacks based on availability of inserter
Attacks based on the presence ofwatermark inserter are easy to perf orm since they make use ofsimilarity between an original watermark and additionally added ones by using the same inserter and key. In this paper, a novel watermarking scheme capable ofresisting inserter attacks is proposed. Watermark signals corresponding to the same key are mutually independent ifthey are randomly selected using the described technique. Thus the inserter attack is invalidated. Performance ofthe proposed method is studied, and simulation experiments presented. ? 2002 Elsevier Science B.V. All rights reserved.
662359
Language and Task Independent Text Categorization with Simple Language Models
We present a simple method for language independent and task independent text categorization learning, based on character-level n-gram language models. Our approach uses simple information theoretic principles and achieves effective performance across a variety of languages and tasks without requiring feature selection or extensive pre-processing. To demonstrate the language and task independence of the proposed technique, we present experimental results on several languages---Greek, English, Chinese and Japanese---in several text categorization problems---language identification, authorship attribution, text genre classification, and topic detection. Our experimental results show that the simple approach achieves state of the art performance in each case.
12782129
Computational measures corresponding to perceptual textural features
Texture is a very important image feature extremely used in various image processing problems. It has been shown that humans use some perceptual textural features to distinguish between textured images or regions. Some of the most important features are coarseness, contrast, direction and busyness. In this paper a new method based on the autocovariance function to estimate quantitatively these features is shown and the correspondence between these computational measures and the psychological ones made by human subjects is shown using some psychometric method.
15396849
Convex grouping combining boundary and region information
Convexity is an important geometric property of many natural and man-made structures. Prior research has shown that it is imperative to many perceptual-organization and image-understanding tasks. This paper presents a new grouping method for detecting convex structures from noisy images in a globally optimal fashion. Particularly, this method combines both region and boundary information: the detected structural boundary is closed and well aligned with detected edges while the enclosed region has good intensity homogeneity. We introduce a ratio-form cost function for measuring the structural desirability, which avoids a possible bias to detect small structures. A new fragment-pruning algorithm is developed to achieve the structural convexity. The proposed method can also be extended to detect open boundaries, which correspond to the structures that are partially cropped by the image perimeter and incorporate a human-computer interaction for detecting a convex boundary around a specified point. We test the proposed method on a set of real images and compare it with the Jacobs'convex-grouping method
122573148
Shape correspondence through landmark sliding
Motivated by improving statistical shape analysis, this paper presents a novel landmark-based method for accurate shape correspondence, where the general goal is to align multiple shape instances by corresponding a set of given landmark points along those shapes. Different from previous methods, we consider both global shape deformation and local geometric features in defining the shape-correspondence cost function to achieve a consistency between the landmark correspondence and the underlying shape correspondence. According to this cost function, we develop a novel landmark-sliding algorithm to achieve optimal landmark-based shape correspondence with preserved shape topology. The proposed method can be applied to correspond various 2D shapes in the forms of single closed curves, single open curves, self-crossing curves, and multiple curves. We also discuss the practical issue of landmark initialization. The proposed method has been tested on various biological shapes arising from medical image analysis and validated in constructing statistical shape models.