Iterative Reconstruction?Reprojection: An Algorithm for Limited Data Cardiac-Computed Tomography

Cardiac X-ray computed tomography (CT) has been limited due to scanning times which are considerably longer (1 s) than required to resolve the beating heart (0.1 s). The otherwise attractive convolution-backprojection algorithm is not suited for CT image reconstruction from measurements comprising an incomplete set of projection data. In this paper, an iterative reconstruction-reprojection (IRR) algorithm is proposed for limited projection data CT image reconstruction. At each iteration, the missing views are estimated based on reprojection, which is a software substitute for the scanning process. The standard fan-beam convolution-backprojection algorithm is then used for image reconstruction. The proposed IRR algorithm enables the use of convolution-backprojection in limited angle of view and in limited field of view CT cases. The potential of this method for cardiac CT reconstruction is demonstrated using computer simulated data.     

Minimization of SONET ADMs in ring networks revisited

We design improved approximation algorithms for two variants of the ADM minimization problem. SONET add-drop multiplexers (ADMs) are the dominant cost factor in SONET/WDM rings. The number of SONET ADMs required by a set of traffic streams (lightpaths) in a ring is determined by the routing and the wavelength assignment of the traffic streams. We consider both the arc version where the route of each traffic stream is given as input, and the chord version, where the routing is to be decided by the algorithm. The goal in both cases is to assign wavelengths so as to minimize the total number of used SONET ADMs.     

Organizational and spatial dynamics of attentional focusing in hierarchically structured objects.

Is the focusing of visual attention object-based, space-based, both, or neither? Attentional focusing latencies in hierarchically structured compound-letter objects were examined, orthogonally manipulating global size (larger vs. smaller) and organizational complexity (two-level structure vs. three-level structure). In a dynamic focusing task, participants successively identified the global and local letters in the same trial. Overall response latencies were generally longer for larger versus smaller global objects and for three-level versus two-level object structure, indicating that attentional focusing time increases both with the magnitude of change in attentional aperture size and with the number of traversed levels of object structure. Additional experiments showed that this pattern is unique to tasks that require dynamic attentional focusing. Taken together, the results support a hierarchical object-based-spatial model of attentional focusing. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

On the numerical solution of two coupled nonlinear partial integro-differential equations related to the optimal control of a nonlinear noisy oscillator

This paper deals with the optimal control of a nonlinear stochastic thrid-order oscillator. It is shown that, in order to implement the optimal feedback control law, a set of two coupled nonlinear partial integro-differential equations has to be solved. A finite difference algorithm for the solution of these equations is proposed, and its efficiency and applicability are demonstrated with examples.     

Improving malware detection by applying multi-inducer ensemble

Detection of malicious software (malware) using machine learning methods has been explored extensively to enable fast detection of new released malware. The performance of these classifiers depends on the induction algorithms being used. In order to benefit from multiple different classifiers, and exploit their strengths we suggest using an ensemble method that will combine the results of the individual classifiers into one final result to achieve overall higher detection accuracy. In this paper we evaluate several combining methods using five different base inducers (C4.5 Decision Tree, Naïve Bayes, KNN, VFI and OneR) on five malware datasets. The main goal is to find the best combining method for the task of detecting malicious files in terms of accuracy, AUC and Execution time.     

Open Collaboration within Corporations Using Software Forges

A software forge is a tool platform for collaborative software development, similar to integrated CASE environments. Unlike CASE tools, however, software forges have been designed for the software development practices of the open source community. The authors discuss their experiences using a software forge to bring open source best practices into corporations. They present the design principles and benefits of a firm-internal software forge and include a case study of how one project at SAP benefitted significantly from being on the forge.     

Elastic constants of porous silver compacts after acid assisted consolidation at room temperature

Acid assisted consolidation (AAC) is a technique that provides elevatedlevels of cohesiveness to silver powder compacts without recourse to a high temperature treatment. Ultrasonic techniques were used to measure the elastic constants of high purity silver compacts as a function of several processing variables. The elastic moduli of untreated (NT) samples were found to be significantly lower than those of samples that had undergone AAC and compacted at the same pressure. Post compaction sintering increases the elastic constants of both AAC and NT samples. The results indicate that the elastic constants are dependent not only on the density that was attained but also on the processing route that was followed. The elastic constant of a porous metal, M, can be expressed as M = M ₀ g, where M ₀ is the elastic modulus of the bulk metal, g is a geometrical factor that reflects the interparticle contact area and is a quality factor that depends on the nature of the interparticle interfaces. The results suggest that sound wave velocity is a parameter more appropriate than density for predicting the elastic moduli of porous metallic compacts.