Advanced Materials Research Vols. 217-218

Abstract: In this paper, double embedded elliptical cracks in a weld of pressure vessels under tension was taken into consideration, and stress intensity factors at the crack tip were calculated with the emphasis on the interaction between cracks. It is found that when the distance between the double embedded elliptical cracks is larger than the major semi-axis of the ellipse, influence between the cracks can be neglected. Unlike the single embedded crack, owing to the crack interactions, the point with maximum stress intensity factor is not always at the end of the minor axis of the ellipse, it may swift to the end of major axis, especially when the ellipse is close to a circle.

Abstract: Abstract：The study area of this paper is the slope of Shenhu Area in the northern South China Sea. We interpreted both sub-bottom and single-channel seismic profiles to describe the acoustic characteristic of gas hydrate sediment and to discuss the cause of its formation. We distinguished some abnormal physiognomy and geologic objects that are relative to gas hydrate in profiles. Protuberance, shallow fault, acoustic blank patch, partial enhanced reflection and acoustic blank zone were discovered in the legible sub-bottom profile. The shallow gassy belt locates under the seabed from 34 to 82 m. Contrasting the sub-bottom profile with the data of Chinese first gas hydrate expedition, we believed that the gas in the shallow gassy belt came from the decompounding of gas hydrate in deep stratum. Pockmark, seepage, fold and Bottom Simulating Reflector (BSR) were recognized in the single-channel seismic profile. The depth of BSR is slightly deeper than that of the samples of Chinese first gas hydrate expedition in the study area. We think the BSR in the seismic profile may be the bottom of gas hydrate. Based on the time-depth conversion, we plotted out Oligocene, early Miocene, middle Miocene and Pliocene in the seismic profile according to the sedimentary thickness, sedimentary rate and age of ODP site 1148 and set up the chronology of the gas hydrate sediment.

Abstract: Aerated concrete is a typical non-uniform quasi-brittle materials, the fracture process is very complicated. To slove the problem of cracks in this block walls, a practical analytical method was proposed based on the vertical mortar joint model to solve the equivalent fracture toughness (the critical value which the crack occurred to spread unstable) With the use of the basic principle of composite material mechanics and linear elastic fracture mechanics. Against the results of the related experiments, the standard deviation and the coefficient of variation of Analytical Solution are smaller, , and the equivalent fracture toughness is the effective fracture parameters of independent of specimen size. So the suggested method is more feasible and applicable, which can forecast autoclaved aerated concrete block wall’s cracking and destroying.

Abstract: With the development of fracturing mechanics, there has been growing recognition that the research on the residual stress of heat treatment becomes attractive. Metal cylinder as the research object, through upbuilding the mathmatic model and sovling the heat conduction equation, whose test data are regarded as the boundary condition can be used to get the distributing temperature function of the workpiece. From this function, it can be deducted the quenching residual stress functions of the club-shaped metal that is resulted from heat stress during quenching. The elastic-plastic transition temperature and elastic modulus which are measuerd can be used to get the calculated value of residual stress by this formula.

Abstract: In this study, the adsorption mechanism of cethyltrimethylammounium bromide (CTAB) onto quartz surface from aqueous solution was investigated and also some thermokinetic parameters such as isosteric adsorption enthalpy and entropy for this system were determined through thermogenesis curves determination by microcalorimetry. In addition, the contribution of adsorption to the surface wettability is illustrated according to the experimental results of surface electrical behavior and wetting behavior. This study shows that the wetting behavior of CTAB on quartz surface is determined by the process of its adsorption.

Abstract: The microstructure and properties of 7003 aluminum alloy with and without burning have been investigated by means of electronic tensile machine, optical microscope (OM) and scanning electron microscopy (SEM). The results showed that the burning level of 7003 alloy increases while the ultimate tensile strength (UTS) and yield strength (YS) for the alloy decrease with increasing the solution temperature. When the solution temperature is higher than 763 K, the UTS and YS for the alloy decline fast with wide-range. The remelting structure, namely burnt structure, appeared on the grain boundaries in 7003 aluminum alloy and then weaken grain boundary, hence resulting in the transition of fracture surfaces from transgranular fracture to intergranular fracture.

Abstract: In order to shorten the fussy experimental process in heat treatment of 7003 aluminum alloy, back-propagation (BP) artificial neural network control of scheme has been proposed. The network of arithmetic has been deduced by using gradient descent algorithms. A BP neural network has been established between the heat treatment technique and the hardness. The results indicated that the predicted results are closed to the test results. The weakness that the nonlinear and time variation relationship between heat treatment and the hardness could be approached more accurately, effectively by using single-factor-experiment method has been overcome. Hence providing a effective, economical，rapid way for the heat treatment optimization of nonferrous metals and ferrous metal.

Abstract: Mesoporous cobalt-doped TiO2 (Co-TiO2) material has been synthesized by solid-state reaction route. The textural properties of the samples are monitored by the X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and energy dispersive spectroscopy(EDS), Raman spectroscopy, N2-physisorption, Fourier transform infrared spectroscopy (FT-IR), ultraviolet visible light spectroscopy (UV-Vis) and X-ray photoelectron spectroscopy(XPS). It is shown that the mesoporous Co-TiO2 is consisted of polycrystalline with some amorphous mixture and trace cobalt oxide. Cobalt has been incorporated into the framework of anatase TiO2. The bending vibration at 1124 cm-1 of Co-O-Ti bond in mesoporous Co-TiO2 material is confirmed. Interestingly, it possesses a large BET surface area (97.6 m2/g) and a narrow distribution of pore size presenting a better photocatalytic reactivity for toluene oxidation. Within 150 min irradiation, the maximum conversion (95 mol%) of toluene oxidation is obtained.

Abstract: By combining the improved wavelet neural network and BP neural network, a new structure based on mixed cascade neural network was established. The novel cascade neural network has been used to the oscillopolargriphic signals analysis. By the figure fitting and parameters extracting, we realized the prediction of the simulation samples.The training speed and the predication accuracy can be enhanced by optimizing the network structure and parameters. The result of concentration prediction is satisfied . The method has been applied to the simultaneous determination of p- Nitrochlorobenzene (p-NCB) and o-Nitrophenol (o-NP) in simulation samples with satisfactory results. The Relative error and Recovery of p-NCB、o-NP were 3.76%、96.2%； 4.05%、96.0%, respectively. This novel cascade neural network combines the advantage of wavelet neural networks and BP neural networks, and performs its own functions respectively. It has shown a unique advantage in the overlap peak analyze.

Abstract: In order to keep step with new materials mirrors and its technology of developed of international space optics system, and promote research level of national new material mirror, the optimization methods of new mirror materials were introduced, and the application of new material mirrors was elaborated. The researching technologies and methods of new materials mirror substrate were recommended. The researching technologies and methods of new materials mirror were narrated. And at same time, the new materials mirror technology and directions of our country were pointed out.