Engineering in Action

Improvements in operational performance of the refractory lining of a direct-current electric furnace for cobalt smelting achieved at the Ufaleinikel Joint-Stock Co. in collaboration with the Kombinat Magnezit Joint-Stock Co. are reported.     

A model for volume lighting and modeling

Direct volume rendering is a commonly used technique in visualization applications. Many of these applications require sophisticated shading models to capture subtle lighting effects and characteristics of volumetric data and materials. For many volumes, homogeneous regions pose problems for typical gradient-based surface shading. Many common objects and natural phenomena exhibit visual quality that cannot be captured using simple lighting models or cannot be solved at interactive rates using more sophisticated methods. We present a simple yet effective interactive shading model which captures volumetric light attenuation effects that incorporates volumetric shadows, an approximation to phase functions, an approximation to forward scattering, and chromatic attenuation that provides the subtle appearance of translucency. We also present a technique for volume displacement or perturbation that allows realistic interactive modeling of high frequency detail for both real and synthetic volumetric data.     

Simulation of the kinetics of the autoclave dissolution of copper and nickel sulfides in the presence of oxygen

Kinetic regularities of the oxidative autoclave dissolution of iron, copper, and nickel sulfides when leaching the ore of the Shanuch deposit are investigated in controllable experimental conditions. It is shown that the dissolution rate of sulfides is limited by the oxygen absorption.     

Multidimensional transfer functions for interactive volume rendering

Most direct volume renderings produced today employ 1D transfer functions which assign color and opacity to the volume based solely on the single scalar quantity which comprises the data set. Though they have not received widespread attention, multi-dimensional transfer functions are a very effective way to extract materials and their boundaries for both scalar and multivariate data. However, identifying good transfer functions is difficult enough in 1D, let alone 2D or 3D. This paper demonstrates an important class of 3D transfer functions for scalar data, and describes the application of multi-dimensional transfer functions to multivariate data. We present a set of direct manipulation widgets that make specifying such transfer functions intuitive and convenient. We also describe how to use modern graphics hardware to both interactively render with multidimensional transfer functions and to provide interactive shadows for volumes. The transfer functions, widgets and hardware combine to form a powerful system for interactive volume exploration.     

An increase in intracellular cyclic AMP modulates nitric oxide production in IFN-gamma-treated macrophages

Macrophages treated with IFN-gamma alone are stimulated to produce nitric oxide. The level of nitric oxide production can be enhanced significantly when IFN-gamma treatment is combined with other agents (e.g., LPS, TNF-alpha, IL-2, etc.). We tested the hypothesis that cAMP plays a role in the IFN-gamma-induced activation of macrophages. Our experiments indicate that factors that increase the concentration of cAMP in the murine macrophage cell line ANA-1 can also enhance IFN-gamma-induced production of nitric oxide. PGE2 and cholera toxin increased the production of nitrite (an indicator of nitric oxide production) in IFN-gamma-treated ANA-1 macrophages by at least twofold. These factors produced no increase in nitric oxide production in the absence of IFN-gamma treatment. The increase in nitric oxide production corresponded to an increase in the accumulation of nitric oxide synthase mRNA without a change in stability of mRNA. Dibutyryl cAMP and Sp-cAMPs (a selective activator of cAMP-dependent protein kinase I and II) also increased nitric oxide production in IFN-gamma-treated macrophages. However, at very high concentrations (i.e., >100 microM), the stimulatory effect was decreased. These studies indicate that elevation of intracellular cAMP causes a dose-dependent, biphasic alteration of IFN-gamma-induced nitric oxide production in murine macrophages. Moreover, they suggest that agents that affect nitric oxide synthesis may do so via modulation of the cAMP second messenger system.     

Measurement of the energy spectrum of cosmic-ray induced neutrons aboard an ER-2 high-altitude airplane

Crews working on present-day jet aircraft are a large occupationally exposed group with a relatively high average effective dose from galactic cosmic radiation. Crews of future high-speed commercial aircraft flying at higher altitudes would be even more exposed. To help reduce the significant uncertainties in calculations of such exposures, the atmospheric ionizing radiation (AIR) project, an international collaboration of 15 laboratories, made simultaneous radiation measurements with 14 instruments on five flights of a NASA ER-2 high-altitude aircraft. The primary AIR instrument was a highly sensitive extended-energy multisphere neutron spectrometer with lead and steel shells placed within the moderators of two of its 14 detectors to enhance response at high energies. Detector responses were calculated for neutrons and charged hadrons at energies up to 100 GeV using MCNPX. Neutron spectra were unfolded from the measured count rates using the new MAXED code. We have measured the cosmic-ray neutron spectrum (thermal to >10 GeV), total neutron fluence rate, and neutron effective dose and dose equivalent rates and their dependence on altitude and geomagnetic cutoff. The measured cosmic-ray neutron spectra have almost no thermal neutrons, a large "evaporation" peak near 1 MeV and a second broad peak near 100 MeV which contributes about 69% of the neutron effective dose. At high altitude, geomagnetic latitude has very little effect on the shape of the spectrum, but it is the dominant variable affecting neutron fluence rate, which was eight times higher at the northernmost measurement location than it was at the southernmost. The shape of the spectrum varied only slightly with altitude from 21 km down to 12 km (56-201 g cm-2 atmospheric depth), but was significantly different on the ground. In all cases, ambient dose equivalent was greater than effective dose for cosmic-ray neutrons.     

Resolution Independent NPR-Style 3D Line Textures

This work introduces a technique for interactive walk-throughs of non-photorealistically rendered (NPR) scenes using three-dimensional (3D) line primitives to define architectural features of the model, as well as indicate textural qualities. Line primitives are not typically used in this manner in favour of texture mapping techniques which can encapsulate a great deal of information in a single texture map, and take advantage of GPU optimizations for accelerated rendering. However, texture mapped images may not maintain the visual quality or aesthetic appeal that is possible when using 3D lines to simulate NPR scenes such as hand-drawn illustrations or architectural renderings. In addition, line textures can be modified interactively, for instance changing the sketchy quality of the lines. The technique introduced here extracts feature edges from a model, and using these edges, generates a reduced set of line textures which indicate material properties while maintaining interactive frame rates. A clipping algorithm is presented to enable 3D lines to reside only in the interior of the 3D model without exposing the underlying triangulated mesh. The resulting system produces interactive illustrations with high visual quality that are free from animation artifacts.     

Structure of oxidative and sulphate-clorinating roasting products of nickel converter matte

The structure and phase composition of the nickel converter matte roasting products has been studied in the sulphate-chlorinating process stage. In stages of the converter matte oxidation in the “fluidized bed” and flash smelting remainder roasting together with silvinite the distribution of non-ferrous metals on the phase constituents has been estimated. In the article data from optical spectroscopy, as well as X-ray diffraction, microprobe and chemical analyze are used. As following from the composition of the phases formed during sulphate-chlorinating roasting and thermodynamic modeling data a number of reactions proceeding in the process is presented.     

A streaming narrow-band algorithm: interactive computation and visualization of level sets

Deformable isosurfaces, implemented with level-set methods, have demonstrated a great potential in visualization and computer graphics for applications such as segmentation, surface processing, and physically-based modeling. Their usefulness has been limited, however, by their high computational cost and reliance on significant parameter tuning. This paper presents a solution to these challenges by describing graphics processor (GPU) based algorithms for solving and visualizing level-set solutions at interactive rates. The proposed solution is based on a new, streaming implementation of the narrow-band algorithm. The new algorithm packs the level-set isosurface data into 2D texture memory via a multidimensional virtual memory system. As the level set moves, this texture-based representation is dynamically updated via a novel GPU-to-CPU message passing scheme. By integrating the level-set solver with a real-time volume renderer, a user can visualize and intuitively steer the level-set surface as it evolves. We demonstrate the capabilities of this technology for interactive volume segmentation and visualization.     

Regulation of parturition update. Endocrine and paracrine effectors of term and preterm labor

This article summarizes the role of endocrine and paracrine mediators of human parturition. Gonadal steroids (17 beta--estradiol and progesterone) mediate many of the decidual and uterine contractile functions during early events in labor. Proinflammatory cytokines and chemokines orchestrate many of the events triggering or sustaining active labor at term and in the preterm setting. Several autacoids (prostaglandins, platelet-activating factor) serve proximal activities such as uterine contractility and remodeling of the cervical extracellular matrix leading to dilatation and effacement. As the biochemical participants during parturition become more clearly understood, it will be possible to develop improved surveillance, management, and treatment strategies for preterm labor.