VRMosaic: Web access from within a virtual environment

For the foreseeable future, users of virtual reality systems will likely spend more time in the “real” environment than in a virtual environment. In the “real” environment, users access much of their data using flat screen applications, which include tools such as authoring and analysis programs and even hyperlinked browsers. We believe that users will find VEs more appealing if they can import their flat screen applications. We also believe that the World Wide Web infrastructure, and supporting tools such as NCSA Mosaic, Netscape's Navigator, and Sun's HotJava, have become a de facto standard both for making data available and allowing limited interaction with that data. These beliefs motivated us to develop a technology for porting flat screen applications based on the 3.1 version of the InterViews toolkit into VR. NCSA Mosaic provided us with a real application that would: (1) test our infrastructure effectively; and (2) provide a compelling application example. We used our “2D interface in VR” infrastructure to port Mosaic into RealEyes, our VR system. Dubbed “VRMosaic”, this application lets users familiar with Mosaic access the Web from within an immersive VE. But VRMosaic is not just an embedded version of NCSA Mosaic-it also allows for VR specific features such as navigation within the VE     

Ultrathin, responsive polymer click capsules

We report a general click chemistry approach for the layer-by-layer assembly of ultrathin, polymer films on particles and the subsequent formation of polymer click capsules (CCs). Poly(acrylic acid) copolymers, synthesized with a minor component of either alkyne (PAA-Alk) or azide (PAA-Az) functionality, were alternately assembled on silica particles. The (PAA-Az/PAA-Alk)-coated particles were subsequently functionalized by exploiting the free alkyne click moieties present in the film upon exposure to an azide-modified rhodamine dye. Further, PAA CCs, obtained following removal of the silica particle template, were shown to exhibit pH-responsive behavior. This was demonstrated by reversible size changes of the CCs upon cycling between basic and acidic solutions. Polymer CCs are anticipated to find applications in various fields, including drug delivery and sensing.     

DNA multilayer films on planar and colloidal supports: sequential assembly of like-charged polyelectrolytes

Multilayer films comprising solely negatively charged polyelectrolytes were sequentially assembled based on DNA hybridization. Films prepared from alternating layers of two-block homopolymeric nucleotides (polyA(20)G(20)/polyT(20)C(20)) grew linearly with increasing layer number, as verified by quartz crystal microgravimetry, UV-vis spectrophotometry and optical microscopy. Urea treatment of the films induced morphological changes, while exposure to low ionic strength solutions resulted in film disassembly. DNA multilayer films were also formed on silica particles, and DNA hollow capsules were obtained following dissolution of the template core.     

Numerical Error in Weighting Function-Based Unsteady Friction Models for Pipe Transients

The accurate simulation of pressure transients in pipelines and pipe networks is becoming increasingly important in water engineering. Applications such as inverse transient analysis for condition assessment, leak detection, and pipe roughness calibration require accurate modeling of transients for longer simulation periods that, in many situations, requires improved modeling of unsteady frictional behavior. In addition, the numerical algorithm used for unsteady friction should be highly efficient, as inverse analysis requires the transient model to be run many times. A popular model of unsteady friction that is applicable to a short-duration transient event type is the weighting function-based type, as first derived by Zielke in 1968. Approximation of the weighting function with a sum of exponential terms allows for a considerable increase in computation speed using recursive algorithms. A neglected topic in the application of such models is evaluation of numerical error. This paper presents a discussion and quantification of the numerical errors that occur when using weighting function-based models for the simulation of unsteady friction in pipe transients. Comparisons of numerical error arising from approximations are made in the Fourier domain where exact solutions can be determined. Additionally, the relative importance of error in unsteady friction modeling and unsteady friction itself in the context of general simulation is discussed.     

Testing the continuum of delusional beliefs: An experimental study using virtual reality.

A key problem in studying a hypothesized spectrum of severity of delusional ideation is determining that ideas are unfounded. The first objective was to use virtual reality to validate groups of individuals with low, moderate, and high levels of unfounded persecutory ideation. The second objective was to investigate, drawing upon a cognitive model of persecutory delusions, whether clinical and nonclinical paranoia are associated with similar causal factors. Three groups (low paranoia, high nonclinical paranoia, persecutory delusions) of 30 participants were recruited. Levels of paranoia were tested using virtual reality. The groups were compared on assessments of anxiety, worry, interpersonal sensitivity, depression, anomalous perceptual experiences, reasoning, and history of traumatic events. Virtual reality was found to cause no side effects. Persecutory ideation in virtual reality significantly differed across the groups. For the clear majority of the theoretical factors there were dose–response relationships with levels of paranoia. This is consistent with the idea of a spectrum of paranoia in the general population. Persecutory ideation is clearly present outside of clinical groups and there is consistency across the paranoia spectrum in associations with important theoretical variables. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of mold precession on channel and macro-segregation in ammonium chloride-water analog castings

Analog castings of two geometrical forms have been studied to observe the effect of continuously changing the direction of gravitational force on patterns of segregation. Molds of slab form, cooled on one side, and of cylindrical form, cooled at the base, were rotated axially at rates from 0 to 10 rpm with the axis of rotation tilted from 0 to 30 deg to the vertical: the development of “A” channel segregation in the former and of “freckel” channels in the latter were recorded photographically, while changes in bulk liquid concentration were followed over time periods up to one hour. It was observed that changing the direction of gravitation, slowly and continuously, markedly retarded or eliminated the formation of segregation channels and that consequent macrosegregation was also retarded and reduced. The application of the principle to foundry practice is discussed.     

behaviorism: a framework for dynamic data visualization

While a number of information visualization software frameworks exist, creating new visualizations, especially those that involve novel visualization metaphors, interaction techniques, data analysis strategies, and specialized rendering algorithms, is still often a difficult process. To facilitate the creation of novel visualizations we present a new software framework, behaviorism, which provides a wide range of flexibility when working with dynamic information on visual, temporal, and ontological levels, but at the same time providing appropriate abstractions which allow developers to create prototypes quickly which can then easily be turned into robust systems. The core of the framework is a set of three interconnected graphs, each with associated operators: a scene graph for high-performance 3D rendering, a data graph for different layers of semantically linked heterogeneous data, and a timing graph for sophisticated control of scheduling, interaction, and animation. In particular, the timing graph provides a unified system to add behaviors to both data and visual elements, as well as to the behaviors themselves. To evaluate the framework we look briefly at three different projects all of which required novel visualizations in different domains, and all of which worked with dynamic data in different ways: an interactive ecological simulation, an information art installation, and an information visualization technique.     

Decoupled optimal design for power electronic circuits with adaptive migration in coevolutionary environment

This paper presents a genetic based decoupled optimal design method for power electronics circuit design using an adaptive collaboration approach in a cooperative coevolutionary environment. The circuit parameters of the power conversion stage and the feedback network of a buck regulator are optimized through two parallel coadaptive genetic based optimization processes. The best candidate of the tunable parameters in one evolutionary process for the design of the power conversion stage is merged to the other evolutionary process for the design of the feedback network as untunable factors through a collaboration controller in which the collaboration strategy is adaptively controlled by a first-order projection of the maximum and minimum bounds of the fitness value of the genes representing the circuit design parameters in each generation. The proposed design methodology is suitable for parallel computation resulting in considerable improvement in searching efficiency. Simulated results of the design of a buck regulator with the proposed approach were verified with experimental results from the actual hardware implementation. It showed that the design with the proposed scheme was compatible with the design specification.     

Indirect approach to continuous time system identification of food extruder

A three-stage approach to system identification in the continuous time is presented which is appropriate for day-to-day application by plant engineers in the process industry. The three stages are: data acquisition using relay feedback; non-parametric identification of the system step response; and parametric model fitting of the identified step response. The method is evaluated on a pilot-scale food-cooking extruder.