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Infrastructure as a Service (IaaS) cloud has been attracting more and more customers as it provides the highest level of flexibility by offering configurable virtual machines (VMs) and computing infrastructures. Public VM images are usually available for customers to customize and launch. However, the 1 to N mapping between VM images and running instances(More)
It has long been recognized that it can be tedious and even infeasible for system administrators to figure out critical security problems residing in full attack graphs, even for small-sized enterprise networks. Therefore a trade-off between analysis accuracy and efficiency needs to be made to achieve a reasonable balance between completeness of the attack(More)
Local Binary Pattern (LBP) has been widely used in texture classification because of its simplicity and computational efficiency. Traditional LBP codes the sign of the local difference and uses the histogram of the binary code to model the given image. However, the directional statistical information is ignored in LBP. In this paper, some directional(More)
We propose a modified alternate direction method for solving convex quadratically constrained quadratic semidefinite optimization problems. The method is a first-order method, therefore requires much less computational effort per iteration than the second-order approaches such as the interior point methods or the smoothing Newton methods. In fact, only a(More)
Software vulnerabilities represent a major cause of cyber-security problems. The National Vulnerability Database (NVD) is a public data source that maintains standardized information about reported software vulnerabilities. Since its inception in 1997, NVD has published information about more than 43,000 software vulnerabilities affecting more than 17,000(More)
Mutual information (MI)-based image registration has been proved to be very effective in multimodal medical image applications. For computing the mutual information between two images, the joint histogram needs to be estimated. As we know, the joint histogram estimation through linear interpolation and partial volume (PV) interpolation methods may result in(More)
Quantifying security risk is an important and yet difficult task in enterprise network security management. While metrics exist for individual software vulnerabilities, there is currently no standard way of aggregating such metrics. We present a model that can be used to aggregate vulnerability metrics in an enterprise network, producing quantitative(More)
This paper presents a novel level set approach to simultaneous tissue segmentation and bias correction of Magnetic Resonance Imaging (MRI) images. We first model the distribution of intensity belonging to each tissue as a Gaussian distribution with spatially varying mean and variance. Then a sliding window is used to transform the intensity domain to(More)
A significant challenge in evaluating network security stems from the scale of modern enterprise networks and the vast number of vulnerabilities regularly found in software applications. A common technique to deal with this complexity is attack graphs, where a tool automatically computes all possible ways a system can be broken into by analyzing the(More)
The wavelet analysis is an eecient tool for the detection of image edges. Based on the wavelet analysis, we present an unsupervised learning algorithm to detect image edges in this paper. A wavelet domain vector hidden Markov tree (WD-VHMT) is employed in our algorithm to model the statistical properties of multiscale and multidirectional (subband) wavelet(More)