Hydrodynamic characteristics of a horizontal flow ejector in a rectangular chamber

The effects of the volumetric flow rate of primary motive water, water height, and the geometric parameters of the hydrodynamiccharacteristics of the gas suction rate and gas phase holdup were investigated in a rectangular chamber (0.22×0.26×1.2 m-high) with a horizontal flow ejector. Gas suction rate increased with increasing volumetric flow rate of the primary motive water, mixing tube length and diffuser length, but it decreased with increasing water height and nozzle diameter. The gas phase holdup was directly proportional to gas suction rate, indicating its corresponding increase with the volumetric flow rate of the primary motive water. Conversely, it decreased with increasing water height and nozzle diameter. However, the mixing tube length affected the gas phase holdup minimally compared to other operating parameters. Both the gas suction rate and gas phase holdup correlated with the dimensionless equations of operating parameters.     

Fast and simple hardware accelerated voxelizations using simplicial coverings

Voxelization of solids, that is the representation of a solid by a set of voxels that approximates it, is an operation with important applications in fields like solid modeling, physical simulation or volume graphics. Moreover, the new generation of affordable 3D raster displays has renewed the interest on fast voxelization algorithms, as the scan-conversion of a solid is a basic operation on these devices. In this paper a hardware accelerated method for computing a voxelization of a polyhedron is presented. The algorithm is simple, efficient, robust and handles any kind of polyhedron (self-intersecting, with or without holes, manifold or non-manifold). Three different implementations are described in detail. The first is a conventional implementation in the CPU, the second is a hardware accelerated implementation that uses standard OpenGL primitives, and the third exploits the capabilities of modern GPUs by using vertex programs.     

MASS TRANSFER LIMITATIONS IN COAL LIQUEFACTION

ABSTRACT

In a number of contributions to coal liquefaction, gas–liquid mass transfer limitation has been referred by neglecting mass transfer limitation of solvent Into solid coal. Reported apparent activation energies of coal liquefaction reactions are In the range of 10–20 kCal/g–mole, which are too low for thermal reactions, Imply that diffusion Is the rate controlling step. In this study, the solvent diffusion effect on solvolysis of vitrinitic macerals In Alberta subbituminous coal has been studied, by performing petrographlc analyses of original coal and liquefaction residues. Quasi–steady state and transient coal–solvent diffusion-chemical reaction models are developed to Interpret the experimental data. Results indicate that solvent diffusion into the reactive maceral most likely be a rate limiting step In coal liquefaction.     

A scalable architecture for 3D map navigation on mobile devices

Mobile devices such as smart phones or tablets are rapidly increasing their graphics and networking capabilities. However, real-time visualization of 3D maps is still a challenging task to accomplish on such limited devices. In this paper, we describe the principles involved in the design and development of a scalable client–server architecture for delivering 3D maps over wireless networks to mobile devices. We have developed a hybrid adaptive streaming and rendering method that distributes the 3D map rendering task between the mobile clients and a remote server. This architecture provides support for efficient delivery of 3D contents to mobile clients according to their capabilities. As a proof of concept, we have implemented a prototype and carried out exhaustive experiments considering different scenarios and hundreds of concurrent connected clients. The analysis of the server workload and the mobile clients performance show that our architecture achieves a great scalability and performance even when using low-end hardware.     

Korovkin-type approximation properties of bivariate q-Meyer-König and Zeller operators

Abstract In the present paper, a bivariate generalization of the Meyer-K?nig and Zeller operators based on the q-integers is constructed. Approximation properties and rate of convergence of these operators are established with the help of a Korovkin theorem for bivariate functions and a Korovkin-type theorem given by Heping [8] and Volkov [14] respectively. Keywords: Positive linear operators, bivariate Korovkin theorem, bivariate modulus of continuity, bivariate Lipschitz class, q-integers.     

Production of 2-hydroxyethyl methacrylate-g-poly(ethylene terephthalate) nanofibers by electrospinning and evaluation of the properties of the obtained nanofibers

Nanofiber production was investigated from poly(ethylene terephthalate) (PET) polymers functionalized with hydroxyethyl methacrylate (HEMA) by grafting of HEMA monomers onto the PET fibers. HEMA grafted PET (PET-g-HEMA) copolymers were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy. PET and PET-g-HEMA were dissolved in trifluoroacetic acid and nanofibers were obtained by electrospinning. It was found that the PET and PET-g-HEMA polymers having grafting yield 20 and 55% could be converted to continuous, smooth, and beadles nanofibers. For characterization of the nanofiber membranes, thermogravimetric analysis, differential scanning calorimeter analysis, surface contact angle measurement, porosity analysis, and mechanical tests were applied. When compared with the original PET nanofibers, the thermal properties and degradation process of PET-g-HEMA nanofibers changed according to the amount of HEMA present in the structure of nanofibers. The contact angles of the nanofibers obtained from PET-g-HEMA polymers decreased whereas the water retention ability of the nanofibers increased compared to original PET nanofibers. The porosity of PET-g-HEMA nanofibers was found be high compared to PET nanofibers and whereas the mechanical properties of PET was higher than PET-g-HEMA nanofibers. The obtained nanofibers can be used in many fields such as biomaterial applications.     

Investigations on the stereochemistry and polymerization of the 1,3-dioxolane derivatives. VIII

Summary The polymerization of 1,3-dioxolane initiated by a new type of initiator — trisubstituted 1,3-dioxolan-2-ylium salts was studied. It was found that the rate of monomer consumption depends on the kind of substituents and anions as well as on the geometrical structure of the isomeric salt used. The dioxolenium salts with an aliphatic substituent at C-2 and with stable anions are more active then salts with an aromatic substituent or those having unstable anions. In all these cases the cis isomers are more active than respective trans salt isomers.     

Treatment of sudden deafness apropos of 447 cases

Tibial nerve and S1 dermatome somatosensory evoked potentials (SSEPs) were recorded before and after iohexol lumbar myelography in order to evaluate possible neurotoxic effects of this contrast medium. No significant change in SSEP latencies nor amplitudes was noted after iohexol myelography, supporting the low neurotoxic profile of this contrast agent. Results were compared to those of a control group of patients before and after lumbar puncture (LP), without injection of contrast agent. In this group also no significant change in SSEP components was found, indicating that a preceding LP does not affect this electrophysiological examination.