Papers by Keyword: Micro-Wave

Abstract: Series of anatase TiO₂ nanoparticles with different particle sizes were prepared by a fast microwave-assisted method and conventional hydrothermal method, using ionic liquids, 1-ethyl-2,3-dimethylimidazole bromide and N-butylpyridinium hexafluorophosphate, and polyethylene glycol as templates, respectively. The crystal structures and morphologies of the nanoparticles were characterized by XRD and SEM. Their light harvesting capabilities and band gap energies were investigated by UV-Vis diffuse reflectance absorption spectra. The surface –OH groups were detected by FT-IR and the photocatalytic activities were estimated by photodegradations of rhodamine B aqueous solutions under simulated sunlight irradiation. The results show that the type of the template and synthetic method affect the particle sizes of the products, and the photocatalytic activities of the TiO₂ nanoparticles are close related with their particle sizes.

Abstract: Rubber wastes cause severe damages for the environment when unsuitably disposed in the environment and represent a challenger for mechanical recycling, because the vulcanized rubber is formed by a tridimensional network with intermolecular sulfur crosslinks. Microwave radiation can lead to the breaking of sulfur crosslinks and so enable the recycling of vulcanized rubbers. The aim of this work was to study the SBR devulcanization by microwave using inorganic salts and nitric acid. Soxhlet extraction and FTIR analyzes were carried out to evaluate the devulcanization degree and chemical modifications in the rubber structure. The results showed that the presence of carbon black in the rubber is an important factor for devulcanization and some metallic ions decrease the sulfur crosslink content. On the other hand, these ions promote the oxidation in the rubber.

Abstract: A new ultrasonication dispersion – microwave cure (UD-MC) method for preparing highly exfoliated layered epoxy/clay nanocomposites was developed. The process was divided into two consecutive stages. In the first stage, the epoxy and organoclay were mixed by high stirring and ultrasonication in the presence of acetone. In the second stage, the mixture of epoxy and organoclay was cured with microwave of 400W and postcured at 135°C. The microstructure of the nanocomposites was characterized with X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results indicated that the basal spacing of the organoclay particles in the epoxy/clay mixture was significantly enlarged, up to around 75Å afther the ultrasonic treatment. The layered clay was highly exfoliated under the microwave energy; and the basal spacing of nanolayers was more than 90Å.

Abstract: We theoretically analyzed the microwave NEMS (Nano- micro- electronic mechanical systems) porous substrate materials and relevant characteristic to NEMS functions to achieve the balance of high performance and the low-cost. And the introduction of the micro fluidic cofferdam development was given at a Glance. ANSYS software was applied on NEMS beam switch simulation. The comparison result was drawn: the threshold voltage of the NEMS beam switch closure increases with metal Young's modulus of the material increases.

Abstract: This As a new type of nano-carbon materials , CNTs have special structure and exhibit excellent mechanical properties, electrical properties, electromagnetic properties, the unique micro-structure, high aspect ratio and high specific surface area. So CNTs have great potential value in many areas. However, there are a large number of catalyst particles and amorphous carbon particles in CNTs during preparation. So carbon nanotubes must be purified before used. This thesis studied the purity of CNTs by microwave technology, improved the surface of the carbon nanotubes, strengthen the structure and properties of carbon nanotubes, reduced the impurities of CNTs, the pretreatment of CNTs has been expanded and got the best parameter of microwave technology

Abstract: In study, Microwave Irradiation enhanced Fenton-Like Process was introduced as a novel technology in the treatment of Landfill Leachate containing refractory organic matters. The sample leachate with initial COD loading of 11434 ~12067 mg•L−1 was collected from the Laohuchong (Shenyang, China) City Landfill. Fenton (FeSO4/H2O2) and Fenton-like (iron tailings/H2O2) reagents coupling with Microwave Irradiation were both studied. The Microwave Irradiation enhanced Fenton-Like Process was conducted under the optimal conditions as follows: 480W of microwave power, 3 min of radiation time, 3.0 of initial pH, 100mL•L−1 of H2O2 and 2g•L−1 of iron tailings. The removal rates of leachate samples with initial COD =11928 mg•L−1 using 1.5g.L-1 FeSO4 and 2.0g.L-1 iron tailings are 45.1% and 42.3% respectively on the condition of 320W MW radiated for 3 min at room temperature. The highest removal rate of the MW Fenton-Like Process is about 46% under the optimum conditions. It demonstrates the Fenton-Like reagent can be used as a substitution of Fenton reagent in Landfill Leachate applications which has extensive application prospect and extraordinary significance in aspects of resource utilization of waste materials and cost saving.

Abstract: Support vector machines (SVMs) are a promising type of learning machine based on structural risk minimization and statistical learning theory, which can be divided into two categories: support vector classification (SVC) machines and support vector regression machines (SVR). The basic elements and algorithms of SVR machines are discussed. As modeling and prediction methods are introduced into the experiment of microwave preparing partially stabilized zirconia (PSZ) and built the stability prediction model, the better prediction accuracy and the better fitting results are verified and analyzed. This is conducted to elucidate the good generalization performance of SVMs, specially good for dealing with nonlinear data.

Abstract: . Silicon carbide (SiC) SITs were fabricated using home-grown epi structures. The gate is a recessed gate - bottom contact (RG - B). We designed that the mesa space 2.7μm and the gate channel is 1.2μm. One cell has 400 source fingers and each source finger width is 100μm. 1mm SiC SIT yielded a current density of 123mA/mm of drain current at a drain voltage of 20V. A maximum current density of 150 mA/mm was achieved with Vd=40V. The device blocking voltage with a gate bias of-16 V was 200 V. Packaged 24-cm devices were evaluated using amplifier circuits designed for class AB operations. A total power output in excess of 213 W was obtained with a power density of 8.5 W/cm and gain of 8.5 dB at 500 MHz under pulse operation.

Abstract: The effects of BaB₂O₄ glass on the synthesis of Ba₂Ti₉O₂₀ were studied. The doping amounts of BaB₂O₄ varied from 0 to 10wt% and the compositions were sintered in the temperature range of 1200~1280^◦C for 2h. The benefit of BaB₂O₄ addition to the densification of the ceramics is apparently due to the liquid phase which accelerates the migration of reactant species, which results in the decreasing of the sintering temperature. With the amount of BaB₂O₄ increased, the microstructure and properties of the ceramics were also changed: BaTi₄O₉ became the major phase instead of Ba₂Ti₉O₂₀, bulk density decreased, and dielectric constant decreased accordingly, while dielectric loss kept small.

Abstract: This paper was developed by microwave measurement on the vegetation dielectric constant through using the rectangular-waveguide at C Band. The measurement system and the method of the measurement will be introduced in detail. We have a standard block of known dielectric constant measurement, and then evaluate the error range. The system of measurement error range is ± 5%.At last, the result of this experiment showed that different density corresponds to different dielectric constant in the case of certain moisture content, and the dielectric constant increases with the density.