Empirical Study of Classification Process for Two-stage Turbo Air Classifier in Series

The suitable process parameters for a two-stage turbo air classifier are important for obtaining the ultrafine powder that has a narrow particle-size distribution, however little has been published internationally on the classification process for the two-stage turbo air classifier in series. The influence of the process parameters of a two-stage turbo air classifier in series on classification performance is empirically studied by using aluminum oxide powders as the experimental material. The experimental results show the following: 1) When the rotor cage rotary speed of the first-stage classifier is increased from 2 300 r/min to 2 500 r/min with a constant rotor cage rotary speed of the second-stage classifier, classification precision is increased from 0.64 to 0.67. However, in this case, the final ultrafine powder yield is decreased from 79% to 74%, which means the classification precision and the final ultrafine powder yield can be regulated through adjusting the rotor cage rotary speed of the first-stage classifier. 2) When the rotor cage rotary speed of the second-stage classifier is increased from 2 500 r/min to 3 100 r/min with a constant rotor cage rotary speed of the first-stage classifier, the cut size is decreased from 13.16 μm to 8.76 μm, which means the cut size of the ultrafine powder can be regulated through adjusting the rotor cage rotary speed of the second-stage classifier. 3) When the feeding speed is increased from 35 kg/h to 50 kg/h, the 'fish-hook' effect is strengthened, which makes the ultrafine powder yield decrease. 4) To weaken the 'fish-hook' effect, the equalization of the two-stage wind speeds or the combination of a high first-stage wind speed with a low second-stage wind speed should be selected. This empirical study provides a criterion of process parameter configurations for a two-stage or multi-stage classifier in series, which offers a theoretical basis for practical production.

Compensation of Unbalanced Impedance of Asymmetric Wind Power PMSG Compensated by External Circuits in Series

The unbalanced impedance of the asymmetric 3-phase wind power permanent magnet synchronous generator(PMSG)compensated by external circuits in series with the 3-phase windings is investigated in this paper.The asymmetric impedance includes the unbalanced resistances,unbalanced self-inductances,and unbalanced mutual inductances.From the perspective of the second harmonic inductances in dq-frame and from the perspective of the second harmonic power,it is theoretically demonstrated that the original asymmetric 3-phase system with asymmetric impedance can be modified to a balanced system by external circuits consisting of resistances and inductances.Therefore,the second harmonic power and DC bus voltage due to the asymmetries can be suppressed naturally without any software modifications.The feasibility of this compensation method is validated by elaborate experiments at different speeds and under different load condition,although the effectiveness might be slightly affected by the non-linearity of the compensation inductance in practice.

Experimental investigation of photolunlinescence spectra of Yb^(3+) sensitized Er^(3+)-doped glass samples in series

Fabrication technology of the Yb3+:Er3+ co-doped glass samples is introduced. Photolummescence (PL) characteristics of a single sample were experimentally investigated. The PL peak intensities of two samples in series were measured and discussed. The results show that the PL peak intensities of two samples in series depend on pump manners and arrangement of the samples. The better amplification ability can be obtained by two samples in series doped with low-concentration ytterbium instead of a single sample doped with high-concentration ytterbium.

Resting Study of Tracer Experiment on Catalytic Wet Oxidation Reactor under Micro-gravity and Earth Gravity Conditions

The International Space Station（ISS） employs catalytic wet oxidation carried out in a Volatile Reactor Assembly （VRA） for water recycling. Previous earth gravity experiments show that the VRA is very effective at removing polar, low molecular weight organics. To compare the reactor performance under micro-gravity and Earth gravity conditions, a tracer study was performed on a space shuttle in 1999 by using 0.2% potassium carbonate as the chemical tracer. In this paper, the experimental data were analyzed and it is indicated that the reactor can be considered as a plug flow one under both micro-gravity and earth gravity experimental conditions. It has also been proved that dispersion is not important in the VRA reactor under the experimental conditions. Tracer retardation was observed in the experiments and it is most likely caused by catalyst adsorption. It is concluded that the following reasons may also have influence on the retardation of mean residence time ： （1） the liquid can be held by appurtenances, which will retard the mean residence time; （2） the pores can hold the tracer, which can also retard the mean residence time.

Impacts of river impoundment on the riverine water chemistry composition and their response to chemical weathering rate

Currently, most rivers worldwide have been intensively impounded. River damming becomes a big problem, not only in inducing the physical obstruction between upstream and downstream, but also in destroying the natural continuity of river. But the discontinuity of water quality was often neglected, which presents a challenge to traditional river geochemistry research. To understand the changes in basic chemistry of water upstream and downstream of the dam, we investigated the Miaotiao River reservoirs in series in the Wujiang River Basin, and the Hongjiadu, Dongfeng Reservoir on the upper reaches of the Wujiang River. Chemical weathering rates were calculated using the water chemistry data of the reservoir surface and downstream of the dam, in each reservoir, respectively. The results showed that the difference between the chemical weathering rates calculated from reservoir surface water and water downstream of the dam was greater in reservoirs with a longer water retention time. In Hongjiadu Reservoir with the longest water retention time among the studied reservoirs, this difference reaches 9%. As a result, the influence of fiver damming, especially the influence of reservoirs in series, should be taken into account when calculating the chemical weathering rate of a fiver basin.

Avoiding second donor site and the second set of neck vessels in a case of absent peroneal skin perforators

This report describes the procedure of a case in which the skin paddle of the free fibula flap derived its supply solely from a soleal musculocutaneous perforator originating from the posterior tibial system.In contrast,the osteo-muscular component was supplied by the peroneal vascular system.We harvested the skin paddle with its vascular supply from the posterior tibial artery separately,and the osteo-muscular fibula was harvested with its supply from peroneal vessels.In this way,we avoided violation of the second donor site for the skin paddle.In addition,we used the distal end of peroneal vessels to salvage our skin paddle instead of sacrificing another set of neck vessels for anastomosis.This technique may also be utilised in cases where the neck vessels may not be available due to previous surgeries,radiation therapy,or decision by the surgery team to not sacrifice two sets of neck vessels for anastomosis.