Optimization of operational conditions in a submerged membrane bioreactor

In this study, optimization of operational conditions of a submerged membrane bioreactor treating municipal waste-water was studied. Mixed liquid suspended solid (MLSS), membrane flux (J(v)), aeration (Q), ratio of pumping, time to break time (t(p)/t(b)), and ratio of up flow area to down flow area (A Ad) were chosen as the easily manipulable parameters to study their effects on removal efficiency and membrane fouling. Totally, 16 different runs were designed to compare and select the best combination of the 5 parameters. The results showed that the optimal operational conditions were MLSS = 7g(.)L(-1), J(v) = 10L(.)m(-2.)h(-1), Q = 6 m(3.)h(-1), t(p)/t(b)= 4 min/1 min, and A(r)/A(d) = 1.7 m(2)/m(2). Under such conditions, the SMBR could achieve a double win of high removal efficiency and low membrane fouling.

Operational Optimization of GaN Thin Film Growth Employing Numerical Simulation in a Showerhead MOCVD Reactor

A detailed reaction-tran sport model was studied in a showerhead reactor for metal organic chemical vapor deposition of GaN film by using computational fluid dynamics simulation. It was found that flat flow lines without swirl are crucial to improve the uniformity of the film growth, and thin temperature gradient above the suscptor can increase the film deposition rate. By above-mentioned research, we can employ higher h (the distance from the susceptor to the inlet), P (operational pressure) and the rate of susceptor rotation to improve the film growth.

Operational characteristics of a 1.2-MW biomass gasification and power generation plant

In this study, we analyzed the operational characteristics of a 1.2-MW rice husk gasification and power generation plant located in Changxing, Zhejiang province, China. The influences of gasification temperature, equivalence ratio (ER), feeding rate and rice husk water content on the gasification characteristics in a fluidized bed gasifier were investigated. The axial temperature profile in the dense phase of the gasifier showed that inadequate fluidization occurred inside the bed, and that the temperature was closely related to changes in ER and feeding rate. The bed temperature increased linearly with increasing ER when the feeding rate was kept constant, while a higher feeding rate corresponded to a lower bed temperature at fixed ER. The gas heating value decreased with increasing temperature, while the feeding rate had little effect. When the gasification temperature was 700-800C, the gas heating value ranged from 5450-6400kJ/Nm3. The water content of the rice husk had an obvious influence on the operation of the gasifier: increases in water content up to 15% resulted in increasing ER and gas yield, while water contents above 15% caused aberrant temperature fluctuations. The problems in this plant are discussed in the light of operational experience of MW-scale biomass gasification and power generation plants.

Large current gain and low operational voltage permeable metal-base organic transistors based on Au/Al double layer metal base

In order to realize the common-emitter characteristics of the tris(8-hydroxyquinoline) aluminium (Alq(3))-based organic transistors, we used Au/Al double metal layer as the base, thus the vertical metal-base transistors with structure of Al/n-Si/Au/Al/Alq(3)/LiF/Al were constructed. It was found that the contact properties between the base and the organic semiconductors play an important role in the device performance. The utilization of Au/Al double layer metal base allows the devices to operate at high gain in the common-emitter and common-base mode at low operational voltage.

Hybrid permeable metal-base transistor with large common-emitter current gain and low operational voltage

We demonstrate the suitability of N,N'-diphenyl-N,N'-bis(1-naphthylphenyl)-1,1'-biphenyl-4,4'-diamine (NPB), an organic semiconductor widely used in organic light-emitting diodes (OLEDs), for high-gain, low operational voltage nanostructured vertical-architecture transistors, which operate as permeable-base transistors. By introducing vanadium oxide (V2O5) between the injecting metal and NPB layer at the transistor emitter, we reduced the emitter operational voltage.