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Study on the Safety of Tunnel Structure Vibration in Dry Ice Powder Thermal Shock Rock Breaking
Xiaofei Wang,Shaobin Hu,Enyuan Wang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.11
The application of explosive blasting for rock breaking works was not possible in densely populated areas, which caused problems in urban tunnel construction. In the application of dry ice powder thermal shock breaking in tunnel excavation, a vibration monitoring system was employed to monitor the vibration response of the tunnel structure during the breaking process, and it was used to extract the signal characteristics by Hilbert-Huang transformation. Experimental results are as follows: 1) The peak vibration speed was below 50 mm/s for concrete structures safe as long as it was farther than 10 m from the burst hole in the support concrete. 2) Aggregate decay of vibration velocities caused by thermal shock breaking of rock with dry ice powder corresponded to the decay law of the power function. The range of influence of the vibration was considerably smaller compared to that of drilling and blasting the rock; 3) The new rock-breaking technology induced damage can be divided into three regions, with radial fractures generated by high-energy fluids dominating. 4) Hilbert Huang transform extracted signal features more objectively and accurately, with excellent reference for the safety monitoring of tunnel structures.
Xiaofei Wang,Shaobin Hu,Enyuan Wang 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.4
The novel dry ice powder static blasting rock breaking lacked working standards, especially for the vibration safety assessment of the construction site for the protection of the building structure, in comparison with the traditional drill and blast method which had a proven operational process and safety specifications. The Sadovsky vibration velocity prediction formula could only predict the vibration velocity and was project specific. Oscillation parameters that needed to be considered in the vibration safety assessment, such as the dominant frequency of vibration, could not be obtained through empirical formulas. Using the five parameters of hole depth, blast center distance, dry ice powder mass and rock classification as the main influencing factors, BP and RBF neural network models were constructed by Matlab software to predict the peak vibration velocity, main frequency and maximum displacement of dry ice powder blasting. Projection results revealed that it is structurally simpler than the BP neural network and that the RBF was more accurate in predicting the target than the BP network. The results of the study had significant implications for the safe application of the new technology, and more samples of field data need to be obtained in the future, along with the use of more advanced predictive modelling.
PDAODMRP: An Extended PoolODMRP Based on Passive Data Acknowledgement
Cai, Shaobin,Yang, Xiaozong,Wang, Ling The Korea Institute of Information and Commucation 2004 Journal of communications and networks Vol.6 No.4
An ad hoc network is a multi-hop wireless network. Its limited bandwidth and frequently changing topology require that its protocol should be robust, simple, and energy conserving. We have proposed PoolODMRP to reduce its control overhead greatly by its one-hop local route maintenance. However, PoolODMRP still has some shortcomings. In this paper, we propose PDAODMRP (passive data acknowledgement ODMRP) to extend PoolODMRP. Compared with PoolODMRP, PDAODMRP has the following contributions: (1) It knows the status of its downstream forwarding nodes by route information collected from data packets instead of BEACON signal of MAC layer; (2) it max simplifies the route information collected from data packets by pool nodes; (3) it adopts a dynamic local route maintenance to enforce its local route maintenance; (4) it adopts the route evaluation policy of NSMP (neighbor supporting multicast protocol). Compared with PoolODMRP, PDAODMRP has lower control overhead, lower data delivery delay, and lower data overhead.
The effect of A-site element on CO2 resistance of O2-selective La-based perovskite hollow fibers
Jian Gao,Yutai Lun,Yadi Hu,Zijian You,Xiaoyao Tan,Shaobin Wang,Jaka Sunarso,Shaomin Liu 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.53 No.-
Oxygen-selective mixed ionic-electronic conducting (MIEC) ceramic membrane technology enables clean coal combustion and membrane reactor for green chemical synthesis. To be practical in these applications that involve CO2 presence, the membrane materials should have simultaneously high CO2 resistance and oxygen permeation fluxes. This work probed these properties for the perovskite oxide family of La0.6X0.4FeO3-d (X = Mg, Ca, Sr, or Ba), i.e., La0.6Mg0.4FeO3-d (LMF), La0.6Ca0.4FeO3-d (LCF), La0.6Sr0.4FeO3-d (LSF), and La0.6Ba0.4FeO3-d (LBF) in the hollow fiber membrane geometry that is highly suitable for industrial application. LCF hollow fiber displayed the best balance in CO2 resistance and oxygen permeation fluxes.