Opacity is a confidentiality property that characterizes the non-disclosure of specified secret information of a system to an outside observer. In this paper, we consider the enforcement of opacity within the discrete-event system formalism in the presence of multiple intruders. We study two cases, one without coordination among the intruders and the other with coordination. We propose appropri...

We present new hardware-accelerated techniques for rendering surface light fields with opacity hulls that allow for interactive visualization of objects that have complex reflectance properties and elaborate geometrical details. The opacity hull is a shape enclosing the object with view-dependent opacity parameterized onto that shape. We call the combination of opacity hulls and surface light f...

A new opacity correction approach for oversampled volume ray casting is introduced. While the only existing opacity correction method in the literature is based on the assumption of dataset homogeneity, the new opacity correction method introduced in this paper is a faster, generalized voxel-by-voxel approach which does not assume dataset homogeneity. The new opacity correction avoids the datas...

Opacity determines radiation transport through material media. In a plasma source, the primary contributors to atomic opacity are bound–bound line transitions and bound-free photoionization into continuum. We review theoretical methodology for state-of-the-art calculations based on R-matrix method as employed in Project, Iron solution of heretofore unsolved problem broadening autoionizing reson...

Further analysis has been made on the millimeter and submillimeter-wave (100–1600 GHz or 3 mm – 188 μm) atmospheric opacity data taken with the Fourier Transform Spectrometer (FTS) at Pampa la Bola, 4800 m above sea level in northern Chile, which is the site of the Atacama Large Millimeter/submillimeter Array (ALMA). Time-sequence plots of millimeter and submillimeter-wave opacities show simila...

The aim of this research is to develop new image processing models that can be used to characterize single opacities and opacity density within pre-selected regions of interest (ROI). We derive our new image processing models based on the International Labor Organization (ILO) standard for assessing opacity shape and profusion. Pattern Spectrum analysis is used for opacity shape and profusion m...

Transactional memory (TM) algorithms are subtle and the TM correctness conditions are intricate. Decomposition of the correctness condition can bring modularity to TM algorithm design and verification. We present a decomposition of opacity called markability as a conjunction of separate intuitive invariants. We prove the equivalence of opacity and markability. The proofs of markability of TM al...

Guerraoui and Kapalka defined opacity as a safety criterion for transactional memory algorithms in 2008. Researchers have shown how to prove opacity, while little is known about pitfalls that can lead to non-opacity. In this paper, we identify two problems that lead to non-opacity and we prove an impossibility result. We first show that the well-known TM algorithms DSTM and McRT don’t satisfy o...