Design of axial flow fans with high aerodynamic loading

Three blading designs of high pressure ratio axial flow fan with hub/tip ratio of 0.7 were carried out with the use of compressor design technology. The flow coefficient and/or pressure coefficient moved in the range of 0.4 to 0.65 and/or 0.65 to 0.85. In the design computations own secondary losses data were applied. The blading tests proved maximum efficiency over 90% in all variants. The measured values of fan stage pressure coefficient were higher than the theoretical ones at design conditions. It consists in a lower rotor deviation angles in contrast to the design. Therefore some ampirical dependencies were derived.     

Entropy Analysis of a Periodically Oscillating Flat Plate in an Infinite Fluid

In this paper, velocity and thermal boundary layer and entropy generation near the periodically oscillating flat plate, which are heated at a uniform temperature, are described. We will present computational fluid dynamic to solve the problem of vibrating plate in order to find velocity, temperature and entropy distribution of each particle of fluid. The solver, that we will choose is the finite volume. The exact solutions for the classical Stoke’s problem are used to verify the numerical formulation. And it is found that the heat transfer for the considered problem, significantly depends on the oscillation velocity.     

Modeling heat transfer in Bi2Te3–Sb2Te3 nanostructures

Bi₂Te₃–Sb₂Te₃ nanostructures are gaining importance for use in thermoelectric applications following the finding that the Bi₂Te₃–Sb₂Te₃ superlattice exhibits a figure of merit, ZT = 2.4, which is higher than conventional thermoelectric materials. In this paper, thermal transport in the cross-plane direction for Bi₂Te₃–Sb₂Te₃ nanostructures is simulated using the Boltzmann transport equation (BTE) for phonon intensity. The phonon group velocity, specific heat, and relaxation time are calculated based on phonon dispersion model. The interfaces are modeled using a combination of diffuse mismatch model (DMM), and the elastic acoustic mismatch model (AMM). The thermal conductivity for the Bi₂Te₃–Sb₂Te₃ superlattice is compared with the experimental data, and the best match is obtained for specularity parameter, p, of 0.9. The present model is extended to solve for thermal transport in 2-D nanowire composite in which Sb₂Te₃ wires are embedded in a host material of Bi₂Te₃. Unlike in bulk composites, the results show a strong dependence of thermal conductivity, temperature, and heat flux on the wire size, wire atomic percentage, and interface specularity parameter. The thermal conductivity of the nanowire is found to be in the range of 0.034–0.74 depending on the atomic percentage and the value of p.     

A High-Power Gastric Photocoagulator for Fiberoptic Endoscopy

A single quartz fiber delivery system capable of remotely depositing in excess of 9 watts of continuous laser radiation has been developed and tested. Of particular interest in this development was the achievement of a catheter that can be inserted into the biopsy channel of a conventional flexible endoscope for noninvasive control of gastric bleeding. In animal testing, the prototype device was found capable of producing a large useful area of superficial tissue coagulum, effectively controlling gastric hemorrhage. Future clinical application is highly encouraging.     

Engineering a soluble extracellular erythropoietin receptor (EPObp) in Pichia pastoris to eliminate microheterogeneity, and its complex with erythropoietin

The extracellular ligand-binding domain (EPObp) of the humanEPO receptor (EPOR) was expressed both in CHO (Chinese HamsterOvary) cells and in Pichia pastoris. The CHO and yeast expressedreceptors showed identical affinity for EPO binding. Expressionlevels in P.pastoris were significantly higher, favoring itsuse as an expression and scale-up production system. Incubationof EPO with a fourfold molar excess of receptor at high proteinconcentrations yielded stable EPO–EPObp complexes. Quantificationof EPO and EPObp in the complex yielded a molar ratio of oneEPO molecule to two receptor molecules. Residues that are responsiblefor EPOR glycosylation and isomerization in Pichia were identifiedand eliminated by site-specific mutagenesis. A thiol modificationwas identified and a method was developed to remove the modifiedspecies from EPObp. EPObp was complexed with erythropoietin(EPO) and purified. The complex crystallized in two crystalforms that diffracted to 2.8 and 1.9 Å respectively. (Form1 and form 2 crystals were independently obtained at AxyS Pharmaceuticals,Inc. and Amgen, Inc. respectively.) Both contained one complexper asymmetric unit with a stoichiometry of two EPObps to oneEPO.     

Evaluation of Heat Transfer Augmentation in a Nanofluid-Cooled Microchannel Heat Sink

Present investigation deals with appraising heat transfer enhancement of single phase microchannel heat sink (MCHS) by ultra fine Cu particle incorporation in base coolant fluid. The particle diameter is of nanometer size and base fluid in combination of nanoparticles is called nanofluid. Governing equations for fluid flow and heat transfer are based on well established “porous medium model” and accordingly, modified Darcy equation and two-equation model are employed. Appropriate equations for both fluid flow and heat transfer are derived and cast into dimensionless form. Velocity profile is obtained analytically and in order to solve conjugate heat transfer problem a combined analytical–numerical approach is employed. For heat transfer analysis, thermal dispersion model is adopted and latest proposed model for effective thermal conductivity – which considers the salient effect of interfacial shells between particles and base fluid – is integrated into model. The effects of dispersed particles concentration, thermal dispersion coefficient and Reynolds number are investigated on thermal fields and on thermal performance of MCHS. Additionally, the impact of turbulent heat transfer on heat transfer enhancement is considered.     

Meaty flavour compounds formation from the submerged liquid culture of Pleurotus ostreatus

The capacity of oyster mushroom (Pleurotus ostreatus) mycelium to produce meaty flavour compounds in the presence of amino acids and sugars was studied. The submerged liquid culture of P. ostreatus mycelium along with base medium made of defatted soybean powder, sucrose, potassium phosphate, and magnesium sulphate was incubated for 3 days at 25 °C. Cysteine, glutamine, or methionine and fructose, galactose, ribose, or xylose were added to the base medium to study the effect of amino acids and sugars on meaty flavour formation by trained panelists. The flavour compounds were isolated and identified by GC–MS and GC retention time of authentic compounds. The base medium required P. ostreatus, cysteine, ribose, and heat treatment to produce meaty flavour. The sulphur containing heterocyclic compounds such as 2,5‐diethylthiophene, 2‐formyl‐5‐methylthiophene, 3‐ethyl‐2‐formylthiophene, and dimethylformyl thiophene were responsible for meaty flavour. These compounds were formed by non‐enzymatic browning reaction between ribose and cysteine during heat treatment.     

Finite difference solution for radiative–conductive heat transfer of a semitransparent polycarbonate layer

Thermal radiation greatly affects the transient thermal response of translucent materials in many practical applications, such as radiative heat shields and ignition and flame spreads for translucent plastics. However, because of the complexities that transients impose, less work has been done on the transient analysis of combined radiation–conduction heat transfer than on steady‐state analysis. In this study, the transient heat transfer analysis of a polycarbonate (PC) layer was done with the use of the two‐flux method and implicit finite difference formulations. The radiative and conductive properties of PC available in the literature, together with computer implementation prepared on the basis of the two‐flux method and implicit finite difference formulations, were used to obtain the transient thermal response of a PC layer. On the basis of these results, we show that, compared to the conduction‐alone case, the PC layer responded faster when radiation effects were considered. It is also shown that the internal reflectivity of boundaries had a great effect on the thermal response of the layer, whereas the thermal conductivity had a minor influence. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Transient Heat Transfer Analysis of a Layer by Considering the Effect of Radiation

The transient heat transfer analysis of a layer has been studied much less than the steady state. However, transient temperature distribution resulted from including radiation and conduction simultaneously, is significantly different from those obtained by considering conduction alone. In order to include the effect of radiation heat transfer, we must insert the gradient of radiative flux in the energy equation. For this purpose, a variety of multi-flux methods have been suggested. A simplified procedure is the two-flux method, which is the one used in the present paper. This paper is focused on one-dimensional transient heat transfer of a layer using Finite Difference Method. To this end, a computer implementation has been written, which is based on implicit finite difference formulation and is capable of considering effect of radiation. By subjecting the layer to various boundary conditions, the effect of variation of refractive index and scattering on transient temperature distribution is discussed.     

A Road Network Embedding Technique for K-Nearest Neighbor Search in Moving Object Databases

A very important class of queries in GIS applications is the class of K-nearest neighbor queries. Most of the current studies on the K-nearest neighbor queries utilize spatial index structures and hence are based on the Euclidean distances between the points. In real-world road networks, however, the shortest distance between two points depends on the actual path connecting the points and cannot be computed accurately using one of the Minkowski metrics. Thus, the Euclidean distance may not properly approximate the real distance. In this paper, we apply an embedding technique to transform a road network to a high dimensional space in order to utilize computationally simple Minkowski metrics for distance measurement. Subsequently, we extend our approach to dynamically transform new points into the embedding space. Finally, we propose an efficient technique that can find the actual shortest path between two points in the original road network using only the embedding space. Our empirical experiments indicate that the Chessboard distance metric (L) in the embedding space preserves the ordering of the distances between a point and its neighbors more precisely as compared to the Euclidean distance in the original road network.