Search results

Miniature pore pressure transducer (PPT) Druck PDCR81 series are used widely and have been proved to have a good performance in the centrifugal tests in the past few decades. However this product has been off production due to unknown reasons from 2010. Therefore, an alternative PPT is urgently needed in the centrifuge research field. A series of comparison between a new PPT and PDCR81 series had been carried out to check its precision and responding rate at 1g and centrifugal condition. The results show that the new PPT has a nearly equivalent performance to PDCR81 series. Also some suggestions are given to modify this new PPT.

When zirconium alloy is corroded, an oxide film is formed on the surface, which hinders the ion transfer during the corrosion process. Therefore, the analysis of the oxide film is an important part of the research on the corrosion resistance of zirconium alloys. In this paper, two kinds of Zr-Sn-Nb alloys were corroded in 400 °C/10.3 MPa pure steam and 500 °C/10.3 MPa pure steam in autoclave to obtain samples with oxide thickness of 14 um and 18 um respectively. Then they were annealed at 800 °C at a pressure of 10^-4 Pa for 18 h. XRD and WDS studies were used to analyze the structure and oxygen content of the oxide film after annealing. The results indicate that the oxide films of alloys change from zirconium dioxide to zirconium after annealing. The oxygen diffuses into the substrate and its content decreases continuously with increasing diffusion distance. Combined with the SEM analysis of cross-section samples, it is found that the annealed samples are composed of several layers. An oxygen-saturated zirconium layer, a transitional layer with micro-cracks, an oxygen-dissolved α-Zr layer and a β-Zr layer are identified. Based on these results, the mechanism of the ion transfer in the oxide film during annealing is analyzed deeply. It is proposed that space charges in the oxide film have a major impact on deoxidation kinetics. This study provides a new research method for the corrosion mechanism of zirconium alloys.

In order to study the effect of tire operating mode on its safety performance, a high-speed tire test-bed was put forward. The dynamic characteristic of drum was important for test result. To avoid the resonance of loaded drum during operation, the topological optimization analysis of drum with I-shaped structure was fulfilled with the element density as variables and the volume reduction of fifty percent as constraint condition and the first natural frequency as objective function. The optimal density distribution of drum was obtained within the constraint of the first natural frequency. Based on the analysis result of topology optimization, the drum structure with I–shaped was modified. The structure size of the new and improved drum was optimized with 50 iterative calculations using ANSYS. On the condition that the first natural frequency of drum was over 60Hz, the structure size of drum was optimal when the rate of the first natural frequency and total weight was highest and equaled to 0.05391. The optimization results showed the first natural frequency of drum was raised by 21.972Hz and its total weight was reduced by 69.95Kg.

With the rapid development of reinforced earth technology, different reinforced materials are also gradually applied to Reinforced earth. In this paper, we focus on the need for the study of interface characteristics between different reinforced materials and clay, by making indoor drawing test with two kinds of reinforced materials commonly used in engineering and the same clay. The test results show that: the drawing strength between the two reinforced materials and clay both increase with the normal stress increasing, both of their strength envelopes are straight lines; In the drawing test between the warp knitted geogrid and clay, the cohesive strength is 6.65kPa, the friction angle is 21.03°; while the drawing test between the geonet and clay, the cohesive strength is 2.9kPa, the friction angle is 10.96°; The average tensile strength of warp knitted geogrid is 26.4% of genet's, while the drawing strength of warp knitted geogrid in the test is about 48.1% of genet's, so when chosing reinforced materials in some engineerings, it is an important factor that we must consider the particle size and gradation of the filled reinforced materials, selecting the most appropriate size effect.

In the present study, we investigated the protective effect of anthocyanin extract from Lonicera caerulea var. edulis (LCA) on UVC-induced lipid and protein peroxidation using lecithin and Bull Serum Albumin (BSA) in vitro model. We also investigated the protective effect of anthocyanin on UVC induced cell injury in Spleen lymphocytes of mouse via MTT and comet assays. Peroxidation of lecithin and BSA generated by exposure to UVC radiation was significantly decreased by addition with various concentrations of LCA. Moreover, LCA exhibited an inhibitory effect on DNA damage induced by UVC radiation when compared with the control group, the DNA damage decrease at the LCA concentration of 50-200ug/ml, in comet assay. These results indicate that LCA has certain protective effect to ultraviolet radiation damage.

Environmental cross-wind has a influence on cooling capacity of wet cooling tower to a great extent in power plant.The variation of circulating-water temperature difference (Δt) and cooling coefficient of efficiency(η) with cross-wind velocity, circulating water inlet temperature and flow rate, are shown under cross-wind conditions, compared with cases without wind. By using experimental platform of cooling water system based on 300MW thermal power unit,it is found that with cross-wind velocity increasing,cooling temperature difference and cooling efficiency decrease first then increase at the knee point when the velocity value is 0.8m/s. In addition, the correlation betweenΔt ,η and parameters,such as circulating-water inlet temperature and flow rate, is derived for cases with windless conditions.

Chemical mechanical polishing (CMP) has been a widely applied process for nickel-phosphorus (Ni-P) coating hard disk substrate polishing. In this study, colloidal silica-based alkaline slurry was prepared for polishing Ni-P plated substrates and its CMP mechanism was studied with alkali slurry. Effects of the various process parameters such as polishing pressure and plate speed on hard disk substrate were investigated. The results show that the polishing pressure and plate speed have a strong influence on the material removal rate and surface roughness of the hard disk substrate. The oxidization layer formed on hard disk substrate surface after polishing. The nickel ions were bounded with amidocyanogen to form stable and soluble macromolecular amidocyanogen-complex agent, improved selectivity of convex region and concave region, enhanced the chemical reaction uniformity and the mass transfer velocity, and thus high removal rate and low surface roughness could be realized.

In order to analysis the processing and serviceability of soybean protein-PVA fibers, the thermal property is studied by TG and DSC and other methods. The result is compared with that of the wool. The glass transition temperature of soybean protein-PVA fiber is 81°C.The decomposition temperature is 313°C.The heat dry air shrinkage rate is 2.3%. The heat endurance meets with the demand of processing and end use.

Abrasive jet precision finishing is a new machining method, which injects slurry of abrasive and liquid solvent to grinding zone under without feed condition. The machining is simulated by Finite Element Method (FEM) in the paper. Hydrodynamic pressure on modeling of wedge-like grinding zone between wheel and workpiece on abrasive jet finishing with wheel as restraint was established and simulation, based on Navier-Stokes and continuity equations. The liquid hydrodynamic pressure distributing principle and affecting factor were investigated. The relation hydronamic pressure with grinding wheel velocity was stimulated and verified experimentally. The experiment results show that the simulation results are agreement with experiment, so the simulation model can well forecast hydrodynamic pressure distribution at contact zone.

Rock mass is the syntheses composed of kinds of structure and structured surfaces. The joint characters is influencing and controlling the rock mass strength, deformation characteristics and rock mass engineering instability failure in a great degree. Through using the RFPA2D software, which is a kind of material failure process analysis numerical methods based on finite element stress analysis and statistical damage theory, the uniaxial compression tests on numerical model are carried, the impact of the trace length of rock joints and the fault throws on rock mechanics parameters are studied. The results showed that with the gradual increase of trace length,compression strength decreased gradually and its rate of variation getting smaller and smaller, the deformation modulus decreased but the rate of variation larger and larger; with the fault throws increasing, the compression strength first increases and then decreases, when the fault throw is equal to the trace length, the deformation modulus is the largest. When the joint trace length is less than the fault throw, the rate of the deformation modulus is greater than that of trace length, but the deformation modulus was not of regular change.