Accelerating Refractive Rendering of Transparent Objects

In this paper, a technique is proposed for the rendering of transparent objects interactively using the method of refractive rendering. In the proposed technique, the refractive rendering algorithm is performed in two stages, namely the pre‐computation stage and the shading stage. In the pre‐computation stage, ray‐traced information, including directions and positions of rays, are generated by a ray tracing process and are stored in a set of ray lists. In the shading stage, these data are retrieved from the ray lists for computing the shading of an object. Using the proposed technique, photorealistic image of transparent objects and gemstones with various cuttings, material properties, lighting and background can be rendered interactively. By combining the refractive rendering technique with conventional shading techniques, jewelry and crystal designs can be rendered at a much higher speed comparing with conventional ray tracing techniques.     

Algorithms for three-dimensional chemical analysis via multi-energy synchrotron X-ray tomography

The conversion of X-ray tomography images into three-dimensional chemical composition requires accurate mass absorption values, high-quality images, and a robust fitting algorithm. The least-squares fits of the images to a three-dimensional chemical composition can proceed with several different options such as minimal vs. over-determined and/or constrained parameters. This project has investigated the impact of XAFS features and a limited CCD dynamic range. These simulated results are compared to a recent experimental project in which synchrotron X-ray tomography was used to image a polymer blend, and from those images, calculated three-dimensional chemical composition maps of the two-component flame retardant, a brominated phthalimide dimer, Saytex^™ BT-93 and a synergist, antimony(III) oxide (Sb₂O₃).     

The simulation of spin glass model of neural networks by the Wang-Landau algorithm

In the present work, the Hopfield neural network model with infinite-range interactions was simulated by using the Wang-Landau algorithm. All simulations and measurements were done in the replica symmetric and broken regions of the model with discrete ?1 values of random variables. The physical quantities such as energy density, specific heat were evaluated at all temperatures. Our results are in good agreement with the replica symmetric mean field solutions.     

Accurate Depth of Field Simulation in Real Time

We present a new post processing method of simulating depth of field based on accurate calculations of circles of confusion. Compared to previous work, our method derives actual scene depth information directly from the existing depth buffer, requires no specialized rendering passes, and allows easy integration into existing rendering applications. Our implementation uses an adaptive, two‐pass filter, producing a high quality depth of field effect that can be executed entirely on the GPU, taking advantage of the parallelism of modern graphics cards and permitting real time performance when applied to large numbers of pixels.     

Passivation and corrosion behaviours of cobalt and cobalt-chromium-molybdenum alloy

Passivation and corrosion behaviour of the cobalt and cobalt-base alloy Co30Cr6Mo was studied in a simulated physiological solution containing chloride and bicarbonate ions and with pH of 6.8. The oxido-reduction processes included solid state transformations occurring at the cobalt/electrolyte interface are interpreted using theories of surface electrochemistry. The dissolution of cobalt is significantly suppressed by alloying it with chromium and molybdenum, since the alloy exhibited “chromium like” passivity. The structural and protective properties of passive oxide films formed spontaneously at the open circuit potential or during the anodic polarization were studied using electrochemical impedance spectroscopy in the wide frequency range.     

An energy dispersive micro X-ray diffractometer based on a combined system of polycapillary optics

An energy dispersive micro X-ray diffractometer based on a combined system of two polycapillary X-ray lenses is designed. The polycapillary X-ray lens in the excitation channel is either a polycapillary parallel X-ray lens (PPXRL) or a slightly focusing polycapillary X-ray lens (SFPXRL). The polycapillary X-ray lens in the detection channel is a PPXRL. At 6.4 keV and 2θ = 141.5°, the total resolution of the diffractometer based on a SFPXRL in the excitation channel and a PPXRL in the detection channel in Δd/d is 4.8%.     

Pulse control problems under ellipsoidal constraints: Constraint parameters sensitivity

Consideration is given to pulse control problems for the tube of trajectories of the linear differential system under incomplete information on the initial data. Apart from the ordinary requirement for boundedness of variation, a special constraint of the ellipsoidal type is imposed on control actions; at this constraint, vectors of jumps of generalized controls belong to the specified ellipsoid of the corresponding finite-dimensional space. The dependence of the variation of optimal pulse control that solves the control problem for the tube of trajectories on parameters of the ellipsoidal constraint on admissible controls is studied.     

On the existence of periodic motion and the maximum sector bounds for absolute stability of nonlinear nonstationary systems

In this contribution we consider the absolute stability problem. We derive necessary and sufficient conditions for the existence of periodic motion using an operator approach. The results yield an efficient algorithm to approximate the maximum sector bounds for absolute stability numerically.     

Conditions of optimality of the divisional,the functional,and the matrix hierarchy of control

The model is considered of the multilevel hierarchical structure that controls a few “production lines” (sequential business-processes) with functional links by the kinds of performed operations. In the framework of the model many effects are investigated, which take place in practice, in particular, the dependence of optimality of the divisional, the functional, and the matrix hierarchy on the instability of the environment, the degree of standardization, the intensity of functional links, the horizontal and the vertical integration, etc.     

Alloying and microstructure stability in the high-temperature Mo-Si-B system

Multi-phase alloys in the Mo-Si-B system are identified as high-temperature structural materials due to their high melting points (above 2000 °C) and excellent oxidation resistance attributed to the self-healing characteristics of borosilica layer up to 1400 °C. In the current study, the effect of alloying additions to achieve a reduced weight density has been examined in terms of changes in the microstructure and phase stability. The critical factor underlying the microstructural changes is related to the influence of the alloying additions on the stability of the high melting temperature ternary-based Mo₅SiB₂ (T₂) borosilicide phase.