A two-phase level tracking method

Interfacial closure models in most two-fluid system codes for reactor safety are usually tied to the flow regime map through the mean void fraction in a computational cell. When a void fraction discontinuity exists in a computational volume, neither heat nor momentum exchange at the phase interface for this particular cell can be properly represented in finite-difference equations governing the fluid flow. Moreover, finite-difference methods with a fixed, Eulerian grid will inaccurately predict the cell-to-cell convection of mass, momentum and energy when the mean cell macroscopic variables are convected from the cell containing the void fraction front. The adequate modeling of two-phase mixture levels requires the knowledge of front position and void fractions above and below the front. In order to obtain such information, an efficient and simple tracking method was implemented in the TRAC-BWR code (released April 1984). We have tested this method with a simple problem involving a moving two-phase air/water mixture level. The results revealed inconsistencies in the behavior of velocities, pressures and interfacial friction, and some bounded numerical oscillations. Following our numerical experiment, we developed a systematic approach to improve the two-phase level tracking method. We present this approach and the results of implementation in the TRAC-BWR code.     

烷基甙表面活性剂后处理的研究

综述了非离子表面活性剂烷基甙的各种后处理方法，着重叙述了活性炭的吸附脱色及双氧水的氧化脱色技术。     

Blasting practices in a quarry with karstic cavities

The blasting practices in a limestone quarry with karstic cavities have been presented.The existence of karstic cavities in the quarry has reduced blasting efficiency significantly.In order to improve blasting efficiency different blasting strategies(loading holes with ANFO in plastic bag,recording cavity location along the holes and charging the holes according to this information.and modifying blasting pattern according to karstic cavities)had been implemented and the results were evealuated on per ton cost basis.It was concluded that efficient blasting in such aquarries requires determining the size and shape of karstic cavities and based on this information.to modify the balst pattern and charge the holes.The suggested method is to record the cavity along the drill hole and to generate 3D model of cav ities.By doing this,the production cost in the limestone quarry has decreased from 0.407$/5 to 0.354$/t.     

Thermomechanical processing of a twin-roll cast Al–1Fe–0.2Si alloy

A sound homogenization practice is identified for a twin-roll cast Al–1Fe–0.2Si (AA8079) alloy, a popular foil stock with a higher Fe/Si ratio than most other AlFeSi commercial alloys. Homogenization below 793 K produces a very fine dispersion of _c particles which in turn yields a very coarse and heterogeneous grain structure upon interannealing. When the Al–1Fe–0.2Si strip is homogenized above 833 K, _c particles are replaced by relatively coarser Al₃Fe particles with a favorable effect on the recrystallized grain size. It is thus concluded that a homogenization temperature of at least 833 K must be employed to obtain a coarse particle dispersion which in turn would produce a fine grain size after interannealing.     

A grid-connected photovoltaic power conversion system with single-phase multilevel inverter

This paper presents a grid-connected photovoltaic (PV) power conversion system based on a single-phase multilevel inverter. The proposed system fundamentally consists of PV arrays and a single-phase multilevel inverter structure. First, configuration and structural parts of the PV assisted inverter system are introduced in detail. To produce reference output voltage waves, a simple switching strategy based on calculating switching angles is improved. By calculated switching angles, the reference signal is produced as a multilevel shaped output voltage wave. The control algorithm and operational principles of the proposed system are explained. Operating PV arrays in the same load condition is a considerable point; therefore a simulation study is performed to arrange the PV arrays. After determining the number and connection types of the PV arrays, the system is configured through the arrangement of the PV arrays. The validity of the proposed system is verified through simulations and experimental study. The results demonstrate that the system can achieve lower total harmonic distortion (THD) on the output voltage and load current, and it is capable of operating synchronous and transferring power values having different characteristic to the grid. Hence, it is suitable to use the proposed configuration as a PV power conversion system in various applications.     

Forming of AlSi8Cu3Fe alloy in the semi-solid state

AlSi8Cu3Fe alloy is a general purpose die casting alloy widely used to manufacture automotive parts. Forming of this alloy in the semi-solid state could largely eliminate problems inherent in die casting process and thus offers a number of advantages. Low superheat casting was employed in the present work to produce non-dendritic AlSi8Cu3Fe alloy feedstock. The ingots thus obtained were thixoformed in a laboratory press after they were held at 570 °C for 5 min, yielding a microstructure with predominantly α-Al globules and interglobular Si particles. The thixoformed parts attain hardness values as high as 125 HB after T6 heat treatment, implying a considerable age hardening potential. However, with a reheating temperature range of 568–572 °C, thixoforming of AlSi8Cu3Fe alloy components under industrial conditions may be challenging.     

Effect of microbial transglutaminase and sodium caseinate on quality of chicken döner kebab

The effect of microbial transglutaminase (MTGase) and sodium caseinate on the quality of chicken d?ner kebab was investigated. Yield, color, pH, SDS-polyacrylamide gel electrophoresis (SDS-PAGE), texture, and sensory evaluations were measured. The results of SDS-PAGE showed that addition of MTGase with or without sodium caseinate created cross-linking between meat proteins. Texture measurements indicated that the effect of the enzyme on binding properties of chicken meat is more effective if it is used with sodium caseinate (P<0.05). Sensory evaluation was not significantly different statistically among treatments.     

Analysis of fatigue crack tip plasticity in Fe-2.6Si

Saurface roughness analysis, etch-pit, and recrystallization techniques were employed to characterize the plastic deformation zones around fatigue cracks in Fe-2.6wt% Si. Both surface and sub-surface cross-sections are evaluated. The plastic zone size changes significantly in the surface layers. It is correlated with energy release rate, J, because of the elastoplastic nature of crack propagation and a linear correlation is found. The plastic deformation experienced inside the plastic zone is analysed and is reported in terms of equivalent tensile strains. The material in the immediate vicinity of the crack tip experiences large plastic strains under a steep gradient. This region, however, occupies a very small fraction of the plastic zone, the rest of which is deformed to less than 4% plastic strain. In the light of the experimental data, an attempt is made to identify potential sources for the variation in measured plastic zone parameters reported in the literature.