Papers by Author: Bo Li

Abstract: Repairing of past earthquake-damaged members that are highly susceptible to future attack is necessary to prevent civil infrastructure destruction and consequent lives lose.Sprayed basalt FRP composite was tested and presented here as a promising solution.In this study, three 1/2 scaled reinforced concrete frame columns were used to investigate the effectiveness and feasibility.One column was damaged to failure and used as a reference specimen.The other two columns were damaged up to the yielding of main bars simulating deterioration of the structure due to seismic action to a control level.These two columns were repaired with sprayed basalt fiber reinforced polymer (BFPR) composite.Different thicknesses of sprayed BFRP composite were applied.Each specimen was subjected to lateral low-frequency cyclic loading and simultaneous constant axial load to simulate seismic action and dead load respectively.The test result analysis showed that sprayed BFRP can increase the load carrying capacity, enhance the energy absorption capacity, and can effectively restore the strength of past earthquakedamaged RC column.

Abstract: The cental Asian orogenic belt (CAOB) which between the North China Craton and the Siberian Craton is one of the tectono-metallogenic belts in the world. The central Inner Mongolia belongs to the eastern part of the CAOB, recently a series of research and exploration work has been done in this region. However, no breakthrough has been made in the exploration of metal ore. In order to research current mineralization issues in the eastern part of the CAOB, a long magnetotelluric (MT) profile was acquired across the central part of Inner Mongolia. The profile starts within the DongUjimqinqi in the northwest, goes southeastward across the Chagan Obo-Arongqi fault, the Erenhot-Hegenshan fault, the Xilinhot fault and the Linxi fault, and ends around the Xar Moron fault in the northern part of Chifeng city; the strike direction of most faults is southeast; the faults have direct control effect to the magmation and mineralization of this region. The model of electrical structure along the profile can be divided into two regions: widely distributed low resistivity is the key feature north of Nianzigou; high resistance is the key feature south of Nianzigou. The Chagan Obo-Arongqi fault, the Erenhot-Hegenshan fault and the Xilinhot fault all present as a southeastward dipping conductor, which reflects their overthrusting process; there are many high conductivity areas along the faults in the region. The electrical structure to the south of Nianzigou is expressed as a mushroom shape, which reflects the tectonic origin of magmatic rock in this region.

Abstract: This paper studied the dielectric performances and microstructure of the Ba-Ti-B-Si-O glass-ceramics fabricated with different methods. The experimental results showed that the pre-calcined method was an effective way to decrease the sintering temperature in glass-ceramic fabricating process, and the dielectric properties of the LTCC materials were εr ≈10, tanδ ≤ 2×10-3 (@1MHz). This study provided a composite method to fabricate LTCC for different applications that was composed of pre-calcined powders and molten powders with different ratios; Moreover, the dielectric constant and sintering performance of composite LTCC were adjustable by changing the ratio of pre-calcined powders and molten powders.

Abstract: The synthesis, infiltration into a polystyrene opal and luminescence spectroscopy of BaTiO3: Tm3+ were reported in this paper. A photonic band gap and blue up-conversion photoluminescence were achieved in the synthesized inverted opal, respectively demonstrated by reflection spectrum and emission spectrum excited by 650nm laser source at room temperature. Changes of the emission spectroscopy compared with the thulium doped barium titanate reference sample were observed and thus provided evidence for the light inhibition effect of the photonic structure.

Abstract: Nanocrystalline Ag doped silica inverse opals were prepared by a sol-gel chemistry method via templating of polystyrene colloidal crystals. The ordered structures of colloidal crystal templates and inverse opals are characterized by scanning electron microscopy. Ag nanocrystals size is estimated as 20~30nm by Scherrer Formula from X-ray diffraction. The color and the stop band of the inverse opals are characterized by transmission spectrum. And five emission peaks of the nanocrystalline silver clusters are observed from fluorescence spectrum.

Abstract: Infrared-to-visible upconversion phosphors Y2O3: Yb, Er and Gd2O3:Yb, Er with narrow size distribution were synthesized by using a stable microemulsion system, which included triton X-100, n-hexanol, cyclohexane and water. Appearance-controllable nanocrystals were achieved by adjusting the ratios of assistant surfactant and surfactant. The X-ray diffraction patterns of the samples showed that the powders were cubic phases of Y2O3 and Gd2O3, respectively. After calcination with different temperature settings in air atmosphere, the particles were spherical through the observation by scanning electronic microscopy. Red and green upconversion luminescence was obtained under 980 nm infrared excitation. Several contributions to the intensity of upconversion emission were also investigated. These upconversion phosphors may be used as fluorescent labels for the sensitive detection of biomolecule, immunoassay or DNA assays.

Abstract: Tape-casting technology is introduced to fabricate metal-arrayes patterned ceramic substance containing periodic multilayer silver wire structure in the low dielectric constant ceramic matrix for microvave bandgap materials and left hand material application. One important advantage of the metal patterned ceramic substance comparing with the periodic structures fabricated on the printed circuit boards (PCB) using a shadow mask/etching technique is that complex multilayer structure can be designed and fabricated in the ceramic body as well as on the surface by the tape-casting process, while the shadow mask/etching technique technology can only design patterns on the surface of printed circuit boards. An Hp8720ES network analyzer was used to measure the transmission properties of the metal patterned ceramic substance. The experimental result shows some novel properties at X-band microwave frequencies. The metal patterned ceramic substance can be used in the microwave communication, such as microwave antenna.

Abstract: Wide band-gap semiconductor ZnO film with ordered face-centered cubic (FCC) structure air holes was prepared by electrochemical process. The porous ZnO film was prepared in zinc nitrate aqueous solution, using the indium tin oxide (ITO) substrate covered with synthetic opals as cathode by potentiostatic method. In order to improve the filling ratio of ZnO in the opal interstices, various potentials were applied to control the deposition speeds. The porous ZnO film was characterized by X-ray diffraction and Scanning Electron Microscope and a photonic band gap at about 568nm was observed by micro-region reflection spectrometer in ZnO inverse opals.

Abstract: Mn2+-doped Zn2SiO4 inverse opals were synthesized by sol-gel technique combined with the self-assembly of the opal template. Zn2SiO4:Mn2+ precursors were infiltrated into the interstices of the opal template assembled by polystyrene spheres. The polystyrene template was removed by calcining and nanocrystals of Mn2+-doped Zn2SiO4 were obtained in the void of opal template. The inverse opals show photonic crystal behavior and emit yellow light initially with the luminescent peak at 562 nm corresponding with the fact that β-phase is the dominant phase for nanocrystals less than 30nm. As the β-phase transformed to α-phase with the gradual increase of treating temperature and the growth of the crystal, the luminescence from Zn2SiO4:Mn2+ phosphors change from yellow to green.