Large scale production of carbon nanotube arrays on the sphere surface from liquefied petroleum gas at low cost

Liquefied petroleum gas (LPG), a cheap industrial material, is used as carbon source to produce carbon nanotube (CNT) arrays on ceramic spherical surface on a large scale in the floating catalyst process. The ceramic spheres provide huge surface area and good mobility, leading to the mass production of CNT arrays continuously. The arrays obtained from the surface are of good alignment, and the purity is as high as 97.5%. With the decrease of the growth temperature, CNTs in the array form with small-diameter of about 13 nm can be obtained. Therefore, with the industrial fuel as carbon source and the ceramic sphere as substrate, CNT arrays can easily be produced on large scale at low cost.     

Phylogenetic position of sponges in early metazoan evolution and bionic applications of siliceous sponge spicules

Sponges are the oldest and the simplest but not primitive multicellular animals. They represent the earliest evolutionary metazoan phylum still extant. It was a long and painful scientific process to posi-tion the most enigmatic and mysterious metazoan,the Porifera,into their correct phylogenetic place among the eukaryotes in general and multicellular animals in particular. As living fossils,sponges provide the best evidence for the early evolution of Metazoa. More recently,interest has been focused on the bionic applications of sponges' siliceous spicules,after the discovery of their unique structure and high fiber performance. In this review,the emergence of sponges,evolutionary novelties found in sponges,and the phylogenetic position of sponges in early metazoan evolution are highlighted. In ad-dition,the present state of knowledge on silicatein-mediated "biosilica" formation in marine sponges,including the involvement of other molecules in silica metabolism and their potential application in nanobiotechnology and medicine,is given.     

Development and application of flexible substrate sensors in instantaneous heat flux measurement

A new type of sensor with the flexible substrate is introduced. It is applicable in measuring instantaneous heat flux on the model surface in a hypersonic shock tunnel. The working principle, structure and manufacture process of the sensor are presented. The substrate thickness and the dynamic response parameter of the sensor are calculated. Because this sensor was successfully used in measuring the instantaneous heat flux on the surface of a flat plate in a detonation-driven shock tunnel, it may be effective in measuring instantaneous heat flux on the model surface.     

A star-style trust model with the ability of data recovery for trusted computing platform

Varieties of trusted computing products usually follow the mechanism of liner-style chain of trust according to the specifications of TCG. The distinct advantage is that the compatibility with the existing computing platform is preferable, while the shortcomings are obvious simultaneously. A new star-style trust model with the ability of data recovery is proposed in this paper. The model can enhance the hardware-based root of trust in platform measurement, reduce the loss of trust during transfer process, extend the border of trust flexibly, and have the ability of data backup and recovery. The security and reliability of system is much more improved. It is proved that the star-style trust model is much better than the liner-style trust model in trust transfer and boundary extending etc. using formal methods in this paper. We illuminate the design and implementation of a kind of trusted PDA acting on star-style trust model.     

Machining studies of die cast aluminum alloy-silicon carbide composites

Metal matrix composites (MMCs) with high specific stiffness, high strength, improved wear resistance, and thermal properties are being increasingly used in advanced structural, aerospace, automotive, electronics, and wear applications. Aluminum alloy-silicon carbide composites were developed using a new combination of the vortex method and the pressure die-casting technique in the present work. Machining studies were conducted on the aluminum alloy-silicon carbide (SiC) composite work pieces using high speed steel (HSS) end-mill tools in a milling machine at different speeds and feeds. The quantitative studies on the machined work piece show that the surface finish is better for higher speeds and lower feeds. The surface roughness of the plain aluminum alloy is better than that of the aluminum alloy-silicon carbide composites. The studies on tool wear show that flank wear increases with speed and feed. The end-mill tool wear is higher on machining the aluminum alloy-silicon carbide composites than on machining the plain aluminum alloy.     

Influence of isothermal aging on σ precipitation in super duplex stainless steel

The time-temperature-transformation (TTT) curve of the 00Cr25Ni7Mo4N duplex stainless steel was obtained with a Formastor-digital thermal dilatometer, and the influence of isothermal aging on σ precipitation was studied by metallographic observation, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The results show that the decomposition of ferrite phase is accompanied by the formation of σ phase at 750–1000℃, especially in the range of 800–900℃. The longer the aging time, the higher the amount of σ precipitation. The area fraction of various phases remains at a certain value upon the completion of ferrite deformation. The temperature of 850℃ is the most sensitive transaction temperature, the incubation time for the formation of σ precipitation is less than 1 min, and aging for 20 min leads to the complete transformation of ferrite. The σ phase is formed preferentially at the α/α/γ junction, and then grows along the α/α boundary in the matrix.     

Application of artificial neural networks in global climate change and ecological research: An overview

Fields that employ artificial neural networks (ANNs) have developed and expanded continuously in recent years with the ongoing development of computer technology and artificial intelligence. ANN has been adopted widely and put into practice by researchers in light of increasing concerns over ecological issues such as global warming, frequent El Niño-Southern Oscillation (ENSO) events, and atmospheric circulation anomalies. Limitations exist and there is a potential risk for misuse in that ANN model parameters require typically higher overall sensitivity, and the chosen network structure is generally more dependent upon individual experience. ANNs, however, are relatively accurate when used for short-term predictions; despite global climate change research favoring the effects of interactions as the basis of study and the preference for long-term experimental research. ANNs remain a better choice than many traditional methods when dealing with nonlinear problems, and possesses great potential for the study of global climate change and ecological issues. ANNs can resolve problems that other methods cannot. This is especially true for situations in which measurements are difficult to conduct or when only incomplete data are available. It is anticipated that ANNs will be widely adopted and then further developed for global climate change and ecological research.     

Phase field simulation of the 180° domain-switching process in PbTiO<Subscript>3</Subscript> single crystal under an antiparallel electric field

The process of 180° domain switching in PbTiO₃ single crystal under an antiparallel electric field was investigated by the three-dimensional phase field simulation, especially the effect of electric field on the type and duration of domain switching. It is found that the polarization reversal of domains takes place under an antiparallel electric field in PbTiO₃ single crystal. The results of the phase field simulation indicate that there is only 90° domain switching under a weak electric field. With the rise of the electric field, 180° domain switching appears. If the electric field is strengthened further, 90° domain switching disappears and the duration of domain switching is shortened.     

Longitudinal surface cracks of thin slabs

Based on the production practice of medium carbon thin slabs in the CSP plant, the reasons and influencing factors for the formation of longitudinal cracks were investigated, and some industrial measures were taken to eliminate the cracks. The results show that the efficient solutions to reduce longitudinal cracks are improving the performance of the mold powder, stabilizing the mold heat flux, and maintaining a proper taper of the mold during casting. Proper pouring temperature and secondary cooling also play important roles in preventing longitudinal surface cracks.