Advanced Materials Research Vol. 322

Abstract: The amount of SiO₂ on the thermal resistance of the ceramic lined cast pipe fabricated by self-propagating high temperature synthesis technology was investigated. Results indicated that the ceramic-lined composite cast iron pipe had excellent thermal resistance. With the increase of the additive SiO₂ amount, the thicknesses and cavity of the ceramic liner increased, which led to the increase in their thermal resistance. In a given ceramic-lined composite cast iron pipe, its thermal resistance increased with the increase of the center temperature.

Abstract: This paper is concerned with the problem of μ-stability of unbounded time-varying delays neural systems with impulsion. Some μ-stability criteria are derived by using Lyapunov- Krasovski functional method. Those criteria are expressed in the form of linear matrix inequalities (LMIs).

Abstract: Accurately describing wellbore sur-rounding rock mechanics state plays an important role in the research on sidewall stability. Considering the failure behavior of the wellbore rock mass, we divide the rock area to failure zone, damage zone and elastic range. We establish dual porosity with fracture wellbore rock stress calculation model according to failure theory. We calculate an production well ambient stress in a given block, the result of which coincides with actual result measured in field.

Abstract: Fatty acid methyl ester biodiesel was successfully synthesized by the esterification of the palm oil deodorizer distillate (PODD) with methanol, catalyzed by the strongly acidic cation-exchange resin as solid acid in a self-made fixed bed reactor. The reaction condition was optimized, and the product could basically reach both national standard and Germany standard.

Abstract: Seven kinds of natural organic acids were added to moderate artificial contaminated soil to investigate the effects of natural organic acids on growth of maize seedlings and phytoextraction of copper and lead by maize. The results show that the effects of organic acids on plant growth are different in Cu and Pb contaminated soil. The natural organic acids can change the dry matter distribution of the shoot and the root, oxalic acid and tartaric acid can increase the root biomass in different degrees. Oxalic acid and tartaric acid can significantly increase the concentrations and uptake of Cu and Pb in the shoots of maize, indicate that oxalic acid and tartaric acid are potential phytoextraction intensifiers in phytoremediation of Cu and Pb contaminated soil.

Abstract: The skid resistance performance of asphalt pavement on super long continuous downgrades should be designed specially. According to characteristics of super long continuous downgrades which is 52 kilometers long, the skid resistance performance of pavement in end of design life was designed as control index; combined with longitudinal slope distribution, anti-skid control standard were be brought up which was based on the stopping sight distance requirements; The equivalent conversion method for anti-skid axle load was obtained by anti-skid attenuation test; The analysis of skid resistance performance indicate that SMA-16 can’t meet the skid resistance requirements and need to optimize it by using thin anti-skid paving.

Abstract: The problem during magnesium alloy welding is the key bottleneck of magnesium application in aerospace, aircraft, automotive and other industries. AZ91D magnesium welded joint is obtained using tungsten inert gas (TIG) welding method without filler materials and groove. The microstructure, morphology, composition and micro hardness distribution of welded joint are investigated using scanning electronic microscopy (SEM), EDAX and micro hardness experiment. The results show: (1) Well welded joint of AZ91D magnesium alloy using TIG welding method is obtained under the condition of welding current 152A, welding voltage 13.4V, welding velocity 6.5mm/s and 20L/min Argon shielding gas; (2) Microstructure of welded joint consisted of black matrix phase α-Mg, white eutectic α+Mg₁₇Al₁₂ and gray dendrite.

Abstract: Although the structure of PI controller is simple, there are some flaws. In order to overcome the contradictions between the rapid response and overshoot for speed, the model of active disturbance rejection control (ADRC) was established in the paper. The transition process for a given speed was got by tracking - differentiator (TD). The sum of internal and external disturbance is estimated by the extended state observer (ESO). The capability of resisting disturbance is improved for the disturbance compensated timely. Permanent magnet synchronous motor (PMSM) direct torque control based on ADRC scheme is realized. The simulation results have shown its availability.

Abstract: EDTA, EDDS and oxalic acid were added to soil to control the concentrations of the three chelators in soil at 2, 5, 10, 15, 20, 30 mmol/kg, then catalase and peroxydase activities of the soil were determined after 24h to identify the effects of three chelators on enzyme activity of soil. The results showed that the catalase activities of soil treated with oxalic acid and EDTA decreased with the increase of the concentrations (p＜0.01, p＜0.05 respectively), while it rised with the increase of the concentration of EDDS (p＜0.01). EDTA, EDDS and oxalic acid all showed significant stimulation on peroxidase activity of soil, especially at low concentration (2 mmol/kg).