True 3D animation for displaying VLSI modeling data

The authors report on a flexible system that provides visual feedback to VLSI designers with a novel display method. The basic problem is to display simultaneously two or more functions f ₁, f₂, . . ., each of which depends on the two spatial variables x and y. The method is based on results from visual perception experiments, which indicated that the human visual system can view simultaneously two or more images that are separated in depth, even if they are combined (superimposed) over a common spatial domain. Two display modes have been implemented: a gray-level mode and a contour mode in which only the edges separating adjacent regions are displayed in an effort to make things easier for the user. This depth-separation technique allows the viewer to register spatially the x,y distribution of multiple variables in an animation sequence. The technique can be applied to many other situations in which a single-plane episode involves several variables     

On the correspondence from Bayesian log-linear modelling to logistic regression modelling with <Emphasis Type="Italic">g</Emphasis>-priors

Consider a set of categorical variables where at least one of them is binary. The log-linear model that describes the counts in the resulting contingency table implies a specific logistic regression model, with the binary variable as the outcome. Within the Bayesian framework, the g-prior and mixtures of g-priors are commonly assigned to the parameters of a generalized linear model. We prove that assigning a g-prior (or a mixture of g-priors) to the parameters of a certain log-linear model designates a g-prior (or a mixture of g-priors) on the parameters of the corresponding logistic regression. By deriving an asymptotic result, and with numerical illustrations, we demonstrate that when a g-prior is adopted, this correspondence extends to the posterior distribution of the model parameters. Thus, it is valid to translate inferences from fitting a log-linear model to inferences within the logistic regression framework, with regard to the presence of main effects and interaction terms.     

Dynamic 3-D computer graphics for designing a diagnostic tool for patients with schizophrenia

We introduce a novel procedure that uses dynamic 3-D computer graphics as a diagnostic tool for assessing disease severity in schizophrenia patients, based on their reduced influence of top-down cognitive processes in interpreting bottom-up sensory input. Our procedure uses the hollow-mask illusion, in which the concave side of the mask is misperceived as convex, because familiarity with convex faces dominates sensory cues signaling a concave mask. It is known that schizophrenia patients resist this illusion and their resistance increases with illness severity. Our method uses virtual masks rendered with two competing textures: (a) realistic features that enhance the illusion; (b) random-dot visual noise that reduces the illusion. We control the relative weights of the two textures to obtain psychometric functions for controls and patients and assess illness severity. The primary novelty is the use of a rotating mask that is easy to implement on a wide variety of portable devices and avoids the use of elaborate stereoscopic devices that have been used in the past. Thus our method, which can also be used to assess the efficacy of treatments, provides clinicians the advantage to bring the test to the patient’s own environment, instead of having to bring patients to the clinic.     

Triazine networks modified with monofunctional reactive cyanate ester monomers

The preparation of cyanate ester thermosetting resins by coreacting a fluorinated bisphenol A dicyanate (6F-BADCY) monomer with a monofunctional reactive cyanate, namely, the dinonyl phenol cyanate (DNPC), is described in this paper. Our objective in this study was to modify the 6F-BADCY system with reactive diluents of a nonpolar nature and produce matrix resins processable at FR-4 epoxylike conditions. By introducing the monofunctional cyanate as a reactive diluent, it is expected that the molar crosslink density of the resulting network will be reduced. Highly branched triazine polymers will result from this approach. Dinonyl phenol cyanate was quantitatively synthesized by reacting dinonyl phenol with cyanogen bromide in the presence of triethylamine.     

Activation parameters and the catalytic effects of poly(3-alkyl-1-vinylimidazolium) salts on the hydrolysis of neutral phenyl esters

Alkaline hydrolyses of p-nitrophenyl acetate (PNPA) and p-nitrophenyl laurate (PNPL) were studied in the presence of poly(3-methyl-1-vinylimidazolium iodide) (PVII-C₁), poly(3-n-hexadecyl-1-vinylimidazolium iodide) (PVIII-C₁₆) and their monomeric analogs. The polysoap (PVII-C₁₆) was a completely quaternized polyion, in contrast to other polysoap systems that have been studied. The hydrolysis of PNPA was not affected by these polyions. The hydrolysis of PNPL was instead enhanced by the addition of these cationic polyions. The magnitudes of the enhancement were in the order of PVII-C₁₆ > PVII-C₁, which is explained in terms of the hydrophobicity of these polyions. Values of k₂, the rate constant of the polymer substrate complex, indicated that the esters bound to the polymer were more reactive than the free esters. Binding or association constants (K) obtained also increased in the order PVII-C₁₆ > PVII-C₁. Inhibitory results were observed for the hydrolysis of PNPL in presence of 3-n-hexadecyl-1-vinylimidazolium iodide (VII-C₁₆). The activation parameters for these reactions were also investigated.     

Stereo Animation for Very Large Data Bases: Case Study? Meteorology

As technological advances give rise to increasingly more powerful computers, applied mathematicians are able to simulate phenomena of considerable complexity using nurmerical models. One of the problems is how to transform the volminuous output data from a numerical form to a visual one, which is easier for humans to comprehend. This article analyzes a case study from the field of meteorology. A weather simulation, program produces numerical output which defines the values of several variables as functions of the three spatial parameters and time. The output of this model is then used as the input to our grphic rendering system, which displays these complex data sets using stereo animation, employing novel techniques to add realism in the animation sequences. We take advantages of the special geometrical configuration to reduce the computation time by about two orders of magnitude. The value our approach is that our techniques for representing four-dimensional data sets can easily be extended to display phenomena in other disciplines.     

Thermal characterization of a bis-maleimide/bis-cyanate/epoxy thermosetting resin for composites

The thermosetting resin investigated here was a mixture of bis-maleimide and bis-cyanate, frequently referred to as BT (bis-maleimide triazine). Triazine is the reaction product of the cyclotrimerization of bis-cyanate during curing. For circuit board applications, a brominated epoxy resin was blended with BT to impact flame resistance. Resin cure was extensively investigated using a combination of thermoanalytical techniques (thermal analysis, heated cell infrared spectroscopy, and dynamic mechanical analysis). The ultimate glass transition temperature was found to be 240°C, which could only be obtained using cure temperatures above 225°C. At lower temperatures, the reaction does not reach full conversion, since the glass transition temperature of the curing network equals or slightly exceeds the cure temperature. Differential scanning calorimetry (DSC) indicates a minimum of two separate reactions. Fourier transform infrared spectroscopy provided more detailed information on the crosslinking reactions during cure. The onset of cyclotrimerization was found to start at 150°C, correlating with one of the peaks in the DSC. At higher temperatures, the epoxide reacts with the cyanate functionality forming oxazoline ring structures. It was not possible to unambiguously assign the origins of the high temperature peaks in the DSC. These high temperature peaks may be attributed to several reactions, including epoxy homopolymerization and polymerization of bis-maleimide. The high temperature reaction mechanisms warrant further investigation.     

Local versus global contrasts in texture segregation

In a texture pair (TP) yielding a vertical or horizontal edge, the local (luminance or color) contrast or the local orientation of the individual textels is traded off with the global strength of the luminance-, color-, or orientation-defined TP edge so as to keep the latter at the detection threshold. Local and global contrasts are defined along the same (within-domain conditions) or along distinct physical dimensions (transdomain conditions). In the latter case local luminance or color contrast is traded off against global orientation. In all cases TP's are presented for 66.7 or 333.3 ms. Textels differ from the background in either luminance or color so that the TP's are respectively equichromatic or equiluminant. TP edge strength is modulated by means of swapping variable proportions of textels between the two textures in the TP. The observed local--global relationships are fitted with a version of the equivalent noise model for contrast coding modified to include the presentation time factor. The extension of the standard model in the time domain is meant to allow comparison between equivalent noise estimates for variable duration stimuli. Model fits of the within-domain data yield equivalent noise energy values significantly different for color- and luminance-defined TP's but are not applicable for the transdomain experiments, which indicates that global orientation processing is independent of both local luminance and local color contrast insofar as the latter are above the detection threshold. Finally, this study points to the equivalence among the local--global, the equivalent noise, and the statistical approaches to texture segregation.     

Similarities between texture grouping and motion perception: The role of color,luminance, and orientation

We present a series of experiments whose results show strong similarities between textural grouping and motion experiments. A family of stimuli consisting of elements of different colors, luminance-polarity, and orientation are used in experiments in both eliciting textural grouping and detection of apparent motion. Among the similarities are that the orientation attribute is a weaker attribute than either color or luminance polarity in eliciting both textural grouping and in detection of apparent motion. However, if the orientation elements are collinear they become salient and contribute toward grouping and apparent motion. The results also indicate that chromatic mechanisms play a significant role in both texture and motion perception. The similarity suggests that perceptual rules governing spatial grouping are analogous to those governing spatiotemporal grouping. The results of these experiments could be used in the areas of image segmentation, pattern recognition, and scientific visualization. © 1996 John Wiley & Sons, Inc.     

A programming model and system infrastructure for real-timesynchronization in distributed multimedia systems

One of the major requirements of distributed multimedia applications is the need to maintain often complex, real-time synchronization constraints. More specifically, it is necessary to be able to manage arbitrary intra- and inter-media synchronization across activities in the distributed environment. Furthermore, it is important that such developments are integrated into emerging object-oriented standards for distributed computing. This paper presents an object-oriented programming model and associated implementation to meet these requirements. The main concepts behind the proposed approach are, firstly, the use of reactive objects for real-time control and synchronization and, secondly, quality of service controlled bindings for predictable communication between objects. The flexibility of the approach is demonstrated by three contrasting examples of real-time synchronization. The implementation extends the real-time capabilities of the Chorus micro-kernel by introducing the concepts of rtports, rthandlers and quality of service controlled connections. The paper demonstrates how reactive objects and bindings are realized on this infrastructure