Papers by Author: Jun Lu

Abstract: the experiments set up a roof model with a solar energy heat storage ventilation. According to the actual demands of experiments, through an economic analysis it results the preliminary investment of the solar energy storage ventilationthe system is between 307~367Yuan/m2 by calculating a energy balance in some way and choosing some type of heat storage phase change materials with a suitable quantity to fit for the model.

Abstract: To expand the bandgap's width of the one-dimensional photonic crystal, a crystal named SiO₂/Metal/MgF₂ is formed by joining some metals into the crystal SiO₂/MgF₂. Furthermore the Finite Difference Time Domain (FDTD) method is used to explore the metals' influence on the crystal's transmission characteristics. The simulation results show that the metals joined could expand the width of the one-dimensional photonic crystal's bandgap effectively and the bandgap's width increases when the metals' thickness increases. Meanwhile the bandgap's characteristic is affected by the metals' material-characteristic. The higher the plasma frequency is, the wider the bandgap's width will be and the more the number of the bandgaps will be. On the other hand, the metals' damping frequency has no significant effect on the bandgap, but would make the bandgap-edge's transmittance decrease slightly.

Abstract: The three common frequency selective surface (FSS) structure, i.e. ring, crosses and Y-aperture which have the same center frequencies are designed, then the three FSS structures are placed at absorbing materials to form complex absorbing structures which are simulated by means of spectral domain approach. Therefore, the effects of different FSS on the characteristics of absorbing materials are studied and the influence laws are given. This research offers reference to element selection for the application of common FSS to absorbing materials.

Abstract: Nano-crystalline titania coatings were prepared by microarc oxidation (MAO) on titanium alloy (TC4) substrates in Na2CO3-KF electrolytic solution. The coating thickness was measured by an optical microscopy with a CCD camera. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to characterize the microstructure and phase composition of coatings. The results show that the coatings are porous nano-crystalline structures mainly composed of anatase and rutile (TiO2). With the increase of anode voltage, both the relative contents of rutile and the sizes of micropores increase gradually, whereas the sizes of the nano-crystalline decrease first and then increase. The prepared samples were employed to study the photo degradation characteristics of Rhodamine B. The results show that the photodegradation performance of the samples prepared under 220V is the best.