基于两粒度语言评价信息的双边匹配决策

针对基于两粒度语言评价信息的双边匹配问题,提出了一种了基于二元语义信息处理的决策方法。在该方法中,首先将两粒度语言评价信息转化为两粒度二元语义信息;考虑以每个主体满意度最大为目标,运用广义二元语义加权平均算子构建了多目标优化模型;进一步地,运用二元语义算术平均算子将多目标优化模型转化为双目标优化模型;根据二元语义的自身特点将双目标优化模型转化为单目标优化模型,进而进行求解来得到匹配方案。最后,给出一个算例说明所提供方法的有效性。

多媒体存储系统的两级粒度方式的设计

Multimedia on demand, such as VOD and AOD, have popularized with the development of network tech-nology recently. The Storage systems of multimedia on demand have some special requirements. The two-level granu-larity is a new method to stripe unites in storage devices. It integrates the virtues of coarse granularity and fine granu-larity.

A New Method for Measurement of Local Solid Flux in Gas-Solid Two-phase Flow

Previous works have shown that the suction probe cannot be used to accurately measure the upward and downward particle fluxes independently. A new method using a single optical probe to measure the local solid flux is presented. The measurement of upward, downward and net solid fluxes was carried out in a cold model circulating fluidized bed (CFB) unit. The result shows that the profile of the net solid flux is in good agreement with the previous experimental data measured with a suction probe. The comparison between the average solid flux determined with the optical measuring system and the external solid flux was made, and the maximum deviationturned out to be 22%, with the average error being about 6.9%. These confirm that the optical fiber system can be successfully used to measure the upward, downward and net solid fluxes simultaneously by correctly processing the sampling signals obtained from the optical measuring system.

Experimental Studies of the Effect of Wall Roughness on Particle Behavior in Gas-Particle Flows

The effect of wall roughness on particle behavior in two-phase flows in a horizontal backward-facing step is studied using a phase-Doppler particle anemometer. The results show that the wall roughness widens the particle velocity probability density distribution, enhances the redistribution of particle velocity into different directions, reduces the particle longitudinal mean velocity and increases the longitudinal and transverse fluctuation velocities and Reynolds shear stress. The effect of roughness on particle motion in the recirculation zone is weaker than that in the fully developed flow region. The effect of roughness for small particles is restricted only in the near-wall region, while that for large particles diffuses to the whole flow field.

Stochastic formulation of particle kinetics in wall-bounded two-phase flows

This paper presents a generalized framework of stochastic modeling for particle kinetics in wall-bounded flow.We modified a reflected Brownian motion process and straightforwardly obtained a Kramers equation for particle probability density function(PDF).After the wall effects were accounted for as a drift from zero in the mean displacement and suppression in the diffusivity of a particle,an analytical solution was worked out for PDF.Three distinguishable mechanisms were identified to affect the profile of particle probability distribution:external forces,turbophoresis effect,and wall-drift effect.The proposed formulation covers the Huang et al.(2009)model of a wall that produces electrostatic repulsion force and van der Waals force,as well as Monte-Carlo solutions for the Peter and Barenbrug(2002)model under a variety of relaxation times.Moreover,it successfully reproduces the two patterns of particle concentration profiles observed in experiments of sediment-laden open-channel flows.The strength of the wall-drift effect was found to be connected with the interaction frequency between particle and wall.Further exploration of the relationship among flow turbulence,particle inertia,and particle concentration is worthwhile.

Responses of Riverbed Particles to Geomorphologic Processes in Aeolian-Fluvial Action Area: A Case Study of the Heilaigou Basin in Inner Mongolia of China

The Heilaigou basin,located in the Inner Mongolia of China,is predominantly influenced by the aeolian-fluvial actions,with complicated sediment transport conditions on the mainstream riverbed.In order to identify the relationship between sedimentary particles and geomorphic processes,mechanisms for the formation of characteristics of grain size composition were investigated by analyzing grain size parameters and external dynamic geomorphologic features.Firstly,the grain size parameters of the riverbed,stream power,maximum grain size of the wind-blown particles and HI values of the mainstream channel were calculated and analyzed,and they were used to establish multiple regression functions of grain size parameters in order to determine the effects of wind and river actions on particles.The results show that sediments in different reaches are formed in different environments：the upper stream is controlled by fluvial and aeolian processes;the sorting properties of riverbed sediments in the middle stream are worse than those in the upper stream since they are affected mainly by fluvial processes as indicated by the larger stream power there;and the particles on the downstream riverbed are likely contributed by the Kubuqi Desert.The size of particles on the riverbed depends on the hydrodynamic conditions,but is not significantly associated with the evolution of landform.Sorting is significantly related to both the hydrodynamic conditions and wind actions.Riverbed deposits brought in by winds likely become finer from the lower to the upper reaches,which are not coarser than 0.88Φ.Generally speaking,the stream power has a major effect on sedimentation characteristics of the riverbed,followed by wind power.

Abrasion characteristic analyses of solid-liquid two-phase centrifugal pump

Based on the solid-liquid two-phase mixture transportation test, the renormalization group (RNG) k-e turbulent model was utilized to simulate the solid-liquid two-phase turbulent flow in a centrifugal pump. By comparing the simulated and experimental results, inner flow features were revealed to improve the abrasion characteristic of the solid-liquid two-phase centrifugal pump. The influence of the solid phase on centrifugal pump abrasive performance is small when the particle volume fraction is less than 2.5%. The aggregation degree of the solid particles is enhanced as the particle diameter increases from 0.1 to 1 mm; however, the mixture density on the pressure side is reduced when the particle diameter increases to 1 mm for the impact of inertia. The wear on the hub is most severe for the shear stress on this position; it is also the largest. The wear characteristic is affected greatly by the parameters of the solid phase. The wear chracteristic can be optimized by decreasing the blade outlet angle. In the modified design, the blade angle is different, whereas the other geometric dimensions remain the same. The improved pump is simulated to contrast with the original pump. The results show that the values of mixture density and shear stress both decrease. The wear condition of the blade is improved to a certain extent.