Advanced Materials Research Vols. 479-481

Abstract: Strengthening and toughening efficiency contributed by calcium carbonate whisker was questioned in this study when the interfacial bonding strength between whisker and Portland cement was increased by adding silica fume. A simple proving experiment was employed and the basic mechanical properties were measured. The results showed that the compressive strength of the composites with silica fume was more sensitive to whisker loading. The flexural strength, split tensile strength and work of fracture were increased no matter with or without silica fume. However, the strengthening and toughening efficiency caused by whiskers in the composites with silica fume was lower than that without silica fume. The scanning electron microscopy images illustrated six mechanisms which can account for the strengthening and toughening effects. It is concluded that crack deflection was the efficient mechanism to toughen cement composite materials. And the interfacial bonding strength should be weak enough to introduce more crack deflection mechanism.

Abstract: SiO2/Ag core-shell composite microspheres were synthesized by silver-seeding method in this paper. In the process, silver nanoparticles as seeds were deposited by repeating the cycle times for further formation of Ag shell. The effects of reaction power and time on the seeding of silica surfaces and the effect of silver ion on the growth of silver shells were investigated. Structures and properties were measured with TEM, UV, FT-IR and Infrared emissometer. The results showed the Ag nanoparticles on the silica surfaces were uniform in size. And the number density was increased growing with the increase of deposition. It was found that the composite exhibited a lower infrared emissivity value in the wavelength range from 8 to 14 μm than that of pure silica as a result of strong reflection of silver metal.

Abstract: There are kinds of indoor pollutants in air. Formaldehyde is the most common pollutions in air, especially after a house was decorated. Formaldehyde pollution sources includes adhesives in the man-made board, paint, paint cleaner, pesticides, antiseptic and so on. Campus is the place where population are relatively dense and people stay relatively for a long time. Measuring the pollution levels of formaldehyde in campus can provide basic data to have better understanding of the environmental poblems. In this study, the formaldehyde concentration inside the campus were carefully analyzed and the results showed that the value were all in safe scope, though in the south gate the value was almost near the safety limit at rush our. The formaldehyde in campus mainly came from the manmade woods and car emitting. Well ventilated and green plant were suggested to lower our surroundings of formaldehyde concentration.

Abstract: A simplified rectangular plate model is built up with three simply supported sides and one free side for the thermal wrinkling analysis of the platelet thermal management devices. By using the static method and the Galerkin's method, the thermal wrinkling of the structural plates under the uniform and no-uniform thermal stress is analyzed; meanwhile, numerical method for solving the platelets with three simply supported sides and one free side is also tested. The analysis method presents in the article could not only apply to the platelet thermal management devices, but also to the the wall of a rectangular vessel with an open top, and to the distortion of a welded plate structure.

Abstract: About the multi-depot vehicle routing problem, considering the transport distance and the number of dispatching vehicles together can effectively reduce the total delivery costs. Firstly establish the corresponding mathematical model by taking the two factors into account. Secondly solve the model by using hybrid genetic algorithms. Thirdly demonstrate the effectiveness of the model and algorithm by an example

Abstract: Subsurface engraving is the process of engraving an image inside a solid object, usually made of a transparent glass/crystal material. A diode-pumped solid-state (DPSS) laser with high beam quality and pulse power is normally used for subsurface engraving. The laser beam can be focused at any 3D point within a 3D envelope. At the focal point, due to high laser intensity, a small fracture or bubble is generated. The fractures can be as small as tens of microns. Currently, the image from subsurface engraving can only be seen, but not felt or touched. This has limited the applications of subsurface engraving to tourist souvenirs or artistic crafts. The authors propose that through some changes to the subsurface engraving process, it is feasible to separate the 3D image from the raw material block, and directly generate a 3D prototype that could not only be visualized, but also touched, or even used for subsequent design, or manufacturing processes. When generating the 3D point cloud, the points should be dense enough so that continuous cracks could be generated. It is expected that the cracks may form a gap, separating the image from the raw material block. In order to facilitate removal of the engraved image from the material block, the material portion that does not belong to the image is cut into small grids, such grids should be easily removed.

Abstract: Intelligent CAD system can be formed if integrating the expert system and mechanical CAD. Components of expert system were analyzed, including integrated databases, knowledge bases, knowledge acquisition, inference engine, explanation mechanism and human-computer interface. The model of design-evaluate-redesign was introduced and discussed. Current situation of research on design expert systems was summarized.

Abstract: Carbon nanotube (CNT) films were one-step catalytically synthesized on silicon substrates by the premixed ethanol flame (PEF). Ferric nitrate and copper nitrate with diverse concentrations, as catalyst precursors, were respectively dissolved into the absolute ethanol to form PEF which could simultaneously offer heat source, carbon source and catalysts. More CNT films were synthesized on silicon substrates when first placed between the core and inner flame and then moved into location between the inner and outer flame. Scanning electron microscopy revealed that the morphologies of CNT films were greatly influenced by the catalyst precursors and locations of silicon substrates in PEF. CNT films synthesized by the copper nitrate PEF had a smaller tube diameter (~20 nm) and lower ratio of amorphous carbon (43.82%). The CNT yield increased along the concentration of catalyst precursors, but the graphitization degree decreased just the reverse. This approach had the potential of large-scale applications in solar cells and reinforced materials.

Abstract: The weatherability of a weathering steel W450QN was compared with a carbon steel Q345 after 5 years atmospheric corrosion. The results indicated that the corrosion resistance was better for W450QN than Q345 based on the corrosion rate. The characteristics of the rust layers indicated the rust layer on W450QN was denser and thicker than that of Q345. The rust layers were mainly composed of goethite (α-FeOOH) with a few of lepidocrocite (γ-FeOOH). W450QN had better weatherability attributed to the alloying elements of copper, chromium and phosphorus enriched in the rust layer.

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.