Synthetical condition assessment of long span suspension bridge based on closeness degree and FAHP

Based on the theory of pattern recognition, the concept of closeness degree between fuzzy sets is brought into the condition assessment of long span bridges. Using the fuzzy analytic hierarchy process （FAHP）, a mathematical model of a multi-objective assessment of a long span suspension bridge is set up. An example is given to show the procedure in the synthetical condition assessment of the Runyang Suspension Bridge, which includes the hierarchical division, the definition of factor weights and fuzzy membership functions, and the calculation of closeness degrees, etc. The assessment combines both the data from the health monitoring system and the manual tests. The classification of evaluation items as well as the calculation of deterministic and nondeterministic items is presented. Compared with the traditional method of point rating, this method can better describe the discreteness of monitoring data and the fuzziness in the condition assessment.

Effect of Synthetic Conditions and Thickener Formulation on the Rheological and Tribological Properties of Polypropylene Grease

Polypropylene(PP)grease holds great potential for special industrial applications.In this study,synthetic conditions,thickener content,and the ratio of two different molecular weight PPs were investigated systematically using a rheometer,scanning electron microscope,X-ray diffraction,Fourier transform infrared spectrometer,oscillating tribometer,and 3D surface profiler measurements.The results showed that suitable synthetic conditions are two quenching cycles,and the synthetic temperature and time is 240℃for 12 h.The rheological analysis showed that thickener content and different proportions of the two PP molecular weights have a significant influence on the rheological properties of PP grease.High molecular weight PP(H-PP)has a stronger thickening ability than low molecular weight PP(L-PP).The higher the amount of H-PP in the fixed thickener content or the higher the thickener content with a specific proportion,the higher the viscoelasticity of PP grease.The tribological performance is related to the rheological properties.The proportion of two different molecular weight PPs in the thickener content should be appropriate;excessive H-PP content leads to lubrication failure.

Synthesis of Novel Ionic Liquid ([C_4 CNmim]^+ PF_6^-) and Application to Preparation of Polyketone

N-valeronitrile-N'-methylimidazolium hexafluorophosphate ([C 4 CNmim]+ PF 6),as a novel ionic liquid with polar nitrile functional group,was prepared.The structure of the ionic liquid was characterized by using IR and 1 H NMR.As a medium,the ionic liquid plays an important role in copolymerization of carbon monoxide (CO) with styrene (St).Some synthetic conditions were determined,including the usage of ionic liquid,palladium composite catalyst and methanol,CO pressure,reaction time and reaction temperature.The influence of these factors on catalytic activity was analyzed.The results show that the catalytic activity has reached 1 724.1 gStCO/(gPd·h) and the catalyst could be reused 5 times under the optimal condition:composite catalyst 0.015 mmol,ionic liquid 3 mL,methanol 0.75 mL,CO pressure 2MPa,reaction time 2 h and reaction temperature 70℃.This CO/St copolymerization within [C 4 CNmim]+ PF 6 system could facilitate ionic liquids with efficient and economical applications to polymeric materials.

Synthesis and Evaluation of CQC-1—An Oil Field Scale Inhibitor

Most of the oil wells enter the middle and late stages of extraction. After one oil extraction, water injection is needed for secondary extraction. With a large amount of calcium and magnesium ions in the water, which is easy to form a large amount of insoluble scale, its formed barium sulfate and strontium sulfate scale are more difficult to handle than carbonate scale. In order to reduce the difficulty of oil production work, this paper mainly targeted the sulfate scale for experiments, and prepared the scale retardant agent CQC-1. Through orthogonal experimental screening, the mass ratio of itaconate acid:methacrylic acid:AMPS:sodium acrylic sulfonate was 2:1:1:1, increase the amount of evocating agent was 8% and the reaction time was 4h, the sulfate scale inhibitor synthesized at the temperature of 80°C had the best performance. Using scale resistance rate, degradation and salt-resistance, the experimental results showed that the scale resistance rate of CQC-1 reached 90.46%. In the four-week degradation experiment, the degradation rate reached over 71% and was maintained by 80.65% at 150°C, while the scale resistance rate still reached 80.35% in simulated saline. It has excellent scale resistance, temperature resistance, salt-resistance and degradation, and has good development prospects.