Variations of physical properties in pellets containing alumina/carbon powder mixtures during reduction and nitridation

Surface area and porosity of pellets containing alumina/carbon powder mixtures during reduction and nitridation were determined. The experimental results indicated that surface area and porosity of solid samples were decreased by increasing the reaction temperature, grain size, forming pressure and the amount of catalyst. Increasing the molar ratio of C/Al₂O₃ and gas flow rate could decrease the surface area and increase the porosity of the solid sample.     

Analogue implementation of a neural network controller for UPSinverter applications

An analogue neural-network controller for UPS inverter applications is presented. The proposed neural-network controller is trained off-line using patterns obtained from a simulated controller, which had an idealized load-current-reference. Simulation results show that the proposed neural-network controller can achieve low total harmonic distortion under nonlinear loading condition and good dynamic responses under transient loading condition. To verify the performance of the proposed NN controller, a hardware inverter with an analogue neural network (NN) controller (using mainly operational amplifiers and resistors) is built. Additionally, for comparison purposes, a PI controller with optimized parameters is built. Experimental results confirm the simulation results and show the superior performance of the NN controller especially under rectifier-type loading condition. Implementing the analogue neural-network controller using programmable integrated circuits is also discussed     

粗苯放散气体回收系统的开工调试经验

介绍了焦化厂粗苯放散气体回收系统开工调试的经验。     

Free vibration of laminated plates using a finite strip method based on a higher-order plate theory

The finite strip method based on the higher-order plate theory is developed for determining the natural frequencies of laminated plates. This method can accurately predict the through thickness effect of transverse shear deformation. Furthermore, only a few degress of freedom are required in the finite strip method. Some numerical results for various span-to-thickness ratios, material properties and stack sequences are presented for illustrative purposes. The present model provides a better way to obtain more accurate natural frequency results.     

A new process of fabricating inverted-staggered tri-layer thin-filmtransistors

A new method of fabricating a-Si:H TFT with etching-stop structure has been proposed. Only one plasma-enhanced chemical vapor deposition is required in this new method and a PH₃/H₂ plasma treatment during the deposition has been used to form the TFT contact and thus saved another plasma deposition. With this method, a TFT of 500 Å active layer has been fabricated successfully. The drain current and saturation mobility of this device is 2.4×10^-7 A and 0.1 cm²/V sec, respectively, which is comparable to the conventional fabricating method. The plasma treatment will also form an additional leakage path on the TFT top surface and increase the TFT subthreshold slope. However, a current of less than 1 pA at V_G=-2.4 V can still be obtained. The possible mechanism of the contact formation by the plasma treatment is also discussed     

Robust controller with disturbance rejection for hydraulic servosystems

A controller is presented that improves the performance and reduces the sensitivity of hydraulic servo systems in the presence of parameter variations, nonlinear effects, and other disturbances. The control system has enhanced closed-loop stability and can recover from steady-state and transient error quickly and completely. It consists of a servo controller, an auxiliary controller, and a robust controller. Simulation and experimental results demonstrate the validity of the controller     

Synthesis and characterization of block copolymers from D,L-lactide and poly(tetramethylene ether glycol)

The copolymer from D ,L -lactide and poly(tetramethyene ether glycol) (PTMG) was prepared in bulk with an isotributyl aluminum–water–phosphoric acid complex catalyst as the initiator and characterized by H-NMR, GPC, and DSC. The effects of the temperature and the amount of PTMG on the polymerization rate and the molecular weight of copolymers were studied. The behavior of the degradation and delivery rate of Levonorgestrel microspheres in vitro was observed. The results show that the degradation and the delivery rate can be controlled by adjusting the molar rate of hydrophilic and hydrophobic segments of the copolymer © 1995 John Wiley & Sons, Inc.     

两种具有电双稳态的全有机络合物

首次发现两种在室温下即具有电双稳态的全有机（有机-有机）络合物，分别称为MCA＋TCNQ和BBDN＋TCNQ。它们可在真空中制备成薄膜，在数伏电压的作用下，从高电阻至低电阻的跃迁时间小于100ns，因此可作为一次写入的存储器材料。根据我国目前最小刻线宽度的水平，可望在1．6cm2的SiO2平面上做出64Mb的存储器。