Preparation of ZrB_2-SiC Powders via Carbothermal Reduction of Zircon and Prediction of Product Composition by Back-Propagation Artificial Neural Network

Phase pure ZrB2-SiC composite powders were prepared after 1 450℃/3 h via carbothermal reduction route,by using ZrSiO4,B2O3 and carbon as the raw materials.The influences of firing temperature as well as the type and amount of additive on the phase composition of final products were detailedly investigated.The results indicated that the onset formation temperature of ZrB2-SiC was reduced to 1 400℃by the present conditions,and oxide additive（including CoSO4·7H2O,Y2O3 and TiO2）was effective in enhancing the decomposition of raw ZrSiO4,therefore accelerating the synthesis of ZrB2-SiC.Moreover,microstructural observation showed that the as-prepared ZrB2 and SiC respectively had well-defined hexagonal columnar and fibrous morphology.Furthermore,the methodology of back-propagation artificial neural networks（BP-ANNs）was adopted to establish a model for predicting the reaction extent（e g,the content of ZrB2-SiC in final product）in terms of various processing conditions.The results predicted by the as-established BP-ANNs model matched well with that of testing experiment（with a mean square error in 10^（-3） degree）,verifying good effectiveness of the proposed strategy.

Influence of conductive network composite structure on the electromechanical performance of ionic electroactive polymer actuators

The influence of the nanostructure of the conductive network composite(CNC)on the performance of ionic electroactive polymer(IEAP)actuators has been examined in detail.We have studied IEAP actuators consisting of CNCs with different volume densities of gold nanoparticles(AuNPs)and the polymer network.Varying the concentration of AuNPs in CNC thin films was used as a means to control the CNC-ion interfacial area and the electrical resistance of the CNC,with minimum effect on the mechanical properties of the actuator.Increasing the interfacial area and reducing the resistance,while maintaining porosity of the composite,provide means for generating motion of more ions into the CNC at a significantly shorter time,which results in generation of strain at a faster rate.We have demonstrated that cationic strain in actuators with denser CNCs is improved by more than 460%.Denser CNC structures have larger interfacial areas,which results in attraction/repulsion of more ions in a shorter time,thus generation of a larger mechanical strain at a faster rate.Also,time-dependent response to a square-wave voltage was improved by increasing the AuNP concentration in the CNC.Under 0.1 Hz frequency,the cationic strain was increased by 64%when the AuNP concentration was increased from 4 to 20 ppm.

A Luminescent Dicyanodistyrylbenzene-based Liquid Crystal Polymer Network for Photochemically Patterned Photonic Composite Film

A novel photonic composite film based on a luminescent dicyanodistyrylbenzene-based liquid crystal polymer network（LCN） was fabricated by using a silica colloidal crystal as a template. The upper part of inverse opal structure and the luminescence characteristics of dicyanodistyrylbenzene-based moiety endowed the resulting bilayer photonic film with structural color arising from coherent Bragg reflection and fluorescence properties, respectively. A fluorescence enhancement phenomenon was observed in the photonic film due to the overlap between the reflection band and emission band of the fluorescent LCN. More importantly, the photo-induced irreversible Z/E photoisomerization of dicyanodistyrylbenzene-based moiety in the photonic film led to both a reflection spectral shift and an observable fluorescence variation. On the basis of this effective phototuning process, microscopic patterning of photonic film was developed under both fluorescence mode and reflection mode. The work demonstrated here provides a new route to construct photo-responsive photonic film.

Strategies of ＂Power-off Reset＂ Failure for Siemens MM440 in the Application of Gas Press

Gas pressurized fan speed control and remote monitoring was achieved based on three sets of gas pressure MM440 frequency converter control system, through the Profibus-DP network transmission of exchange data and signal instructions. In operation, one converter which adopted ＂ power-off reset＂ has broken down, so as to cause two other gas pressurized frequency converter tripping. This paper proposed method to achieve capture and process failures, and application to converter control system. The result shows that the present method solves the fault, improves the system operation stability and meets the requirement of production.