Analysing the consequence of gas pipeline explosion safety impact
Nowadays, most of the analysis of the explosion of und erground gas pipeline consequences did not consider the tunnel's covering ground conditions. In this paper,the risk are analyzed w ith considering and without considering of covering rock layer of pipe problems, through the relevant modeling, application of M ATLAB software,carried out the simulation to the final blasting effect.And made a final disscion of the two kinds of simulation r esults respectively.
Pipeline two-dimensional impact location determination using time of arrival with instant phase (TOAIP) with piezoceramic transducer array
An impact event on a pipeline generates stress waves that travel along the pipeline, and the traveling stress waves can be easily detected by distributed piezoceramic transducers. To pinpoint impact location on a pipeline, the time of arrival (TOA) is commonly used and the envelope calculated by the Hilbert transform is an effective method to determine the TOA. However, the envelope used to extract the TOA depends on the manual selection of the trigger threshold. In fact, the instant phase, that changes regularly from -pi to pi as the stress wave travels, is an important characteristic parameter of the signal, and the TOA can be determined by the periodicity of the instant phase. However, this fact has been overlooked in calculating TOA in the literature. In this paper, a new method, time of arrival with instant phase (TOAIP), is developed to calculate the TOA without the need of manual selection of the threshold. Taking into account the non-stationarity of the signal and noise interference, short time window Fourier transform and band-pass filter are utilized to extract the useful signal, the TOA is then determined by using the instant phase which is based both the first zero-crossing point of signal and the periodicity of the phase. In general, most of the pipeline impact localization realize one-dimensional positioning along its length direction. Another novelty of this paper is the development of the two-dimensional impact location (TDIL) that can estimate the impact location information along both length and circumferential directions. Experimental studies based on pipeline with distributed lead zirconate titanate (PZT) transducers mounted on the surface of the pipeline are carried out in this research. Both of physical measurements and inversion results have verified the accuracy and reliability of TOAIP and TDIL on the pipeline.
Copper Phthalocyanine Improving Nonaqueous Catalysis of Pseudomonas cepacia Lipase for Ester Synthesis
The nonaqueous catalysis of lipases is significant for synthesis of high pure esters, but they usually behave low catalytic activity due to denaturation and aggregation of enzyme protein in organic phases. To improve the nonaqueous catalysis, the inexpensive copper phthalocyanine was taken as a new carrier on which Pseudomonas cepacia lipase was immobilized by physical absorption, and used for synthesis of hexyl acetate, an important flavor, via transesterification of hexanol and vinyl acetate. Results showed that the desired loading was 10 mg lipase immobilized on 10 mg copper phthalocyanine powder. When the immobilized lipase was employed in the reaction system consisted of 1.5 mL hexanol and 1.5 mL vinyl acetate at 37℃ and 160 rpm, the conversion was five fold of that catalyzed by native lipase after 1 h, and reached 99.0% after 8 h. Undergoing six times of 8-h reuses, the immobilized lipase had an activity attenuation rate 1.22% h− 1, lower than 1.77% h− 1 of native lipase, which meant that the immobilized lipase was more stable. Even at the room temperature and the static state without shaking or stirring, the immobilized lipase could bring conversion 42.8% after 10 h and the native lipase gave 20.1%. Obviously, the immobilized lipase is an available biocatalyst in organic phase and has great potential in food industry.