Mechanism of rock burst induced by fault slip in an island coal panel and hazard assessment using seismic tomography: a case study from Xuzhuang colliery, Xuzhou, China

Changbin Wang,Anye Cao,Guangan Zhu,Guangcheng Jing,Jing Li,Tian Chen 한국지질과학협의회 2017 Geosciences Journal Vol.21 No.3

Rock burst hazards induced by fault slip frequently occur in underground mining and threaten the safety of miners. In this paper, the structures of overlying strata, mechanism of fault slip, and rock burst pre-warning using seismic tomography were investigated in LW7192, a specific island longwall panel in Xuzhuang Colliery. The results show that an asymmetrical “T” structure of overlying strata is formed during LW7192 retreat, and the long hanging length of overlying key strata is maintained due to the short panel width. By analysing a modified fault sliding model, it is found that the time interval between two fault slips has a positive correlation with the energy released therein. The rock burst that occurred in LW7192 has the longest time interval between events compared with other high-energy tremors near the fault, and enormous elastic energies released by fault slip as a form of dynamic load. The superposition of dynamic loads and high stress concentration of the coal-rock mass contributes to the rock burst in LW7192. For forecasting rock burst hazards, seismic tomography was used and the results show that the velocity anomaly regions correspond well with the area of both strong tremors and the rock burst. Ultimately, large-diameter boreholes, directional hydraulic fracturing boreholes, and floor distressing boreholes were taken in the rock burst area, and the pressure relief is proved effective by seismic tomography assessment.

DC-link voltage balance control method considering the wide regulation range in SOR for single-phase cascaded H-bridge rectifier

Wang, Xin,Wang, Chenchen,Gu, Changbin The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.1

In this paper, a DC-link voltage balance control method that considers the wide regulation range in the steady-state operating region is proposed for a single-phase cascaded H-bridge rectifier. A mathematical model of the DC-link voltage is also established while considering the imbalance caused by the inconsistency of the active power absorbed and consumed by the cell. On the basis of the steady-state operating region of the cascaded H-bridge rectifier, the operating loci of different balance methods are analyzed and a novel balance method is proposed. The DC-link voltage regulation range of the proposed method is then compared with that of two other commonly used methods based on the operating locus in the steady-state operating region. The comparison results show that the proposed method has the widest regulation range in the steady-state operating region wherever the cascaded H-bridge rectifier is operated. The experimental results also verify the effectiveness and superiority of the proposed method.

Manipulation Planning with Soft Constraints by Randomized Exploration of the Composite Configuration Space

Jiangping Wang,Shirong Liu,Botao Zhang,Changbin Yu 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.3

In this paper, an efficient and probabilistic complete planning algorithm called Composite-space RRT is presented to address motion planning with soft constraints for spherical wrist manipulators. Firstly, we propose a novel configuration space termed Composite Configuration Space (“Composite Space” for short), which is composed of the joint space and the task space. Then, collision-free paths are generated in the composite space by the Rapidly-exploring Random Trees (RRT) algorithm. Finally, the planned paths in the composite space are mapped into the corresponding joint-space paths by a local planner. As the analytical inverse kinematics (IK) of the spherical wrist is used in the local planner, the proposed Composite-space RRT algorithm is characterized by high efficiency and no numerical iteration. Moreover, this approach can effectively improve the smoothness of the end-effector orientation path. The effectiveness of the proposed algorithm is demonstrated on the Willow Garage’s PR2 simulation platform with two typical orientation-constrained cases.

Passive velocity tomography for mudstone under uniaxial compression using acoustic emission

Anye Cao,Changbin Wang,Guangcheng Jing,Wu Cai,Guangan Zhu,Jing Li 한국지질과학협의회 2017 Geosciences Journal Vol.21 No.1

A passive velocity tomography method using acoustic emission (AE) was used to study characteristics of AE responses and velocity redistributions in mudstone during uniaxial deformation. Two standard cylindrical samples were uniaxially deformed until failure with axial loading rates of 1.00 × 10–3 mm/s and 2.50 × 10–3 mm/s, respectively. AE activities were monitored using eight sensors and every 100 consecutive AE events were used for tomography calculations. For each sample, three typical tomography results were obtained which reflected significant variation of velocity redistributions. From the experimental data, it can be concluded that the stress drop point observed in the stress-strain curves with high energies and AE events indicated coalescence of micro-cracks and formation of the main shear plane. In the initial tomography phase, the velocity difference was low and few AE events were detected. As loading increased, AE events clustered and velocity differences became obvious with high velocities being mainly located near the sample boundary, whereas low velocities begun to propagate from the bottom corner to the core. When approaching failure, velocity anomaly regions further expanded and low velocity regions interconnected with the position being consistent with macro-fractures in the post-failure samples. The positions of the AE events with large energies over 50 μV·s were found to correlate well with high velocity regions in the tomography results whose calculation phase was conducted prior to the occurrence of large energy AE events. This method can be used for the prediction of large energy AE events in rocks under unconfined pressures.

Sintering-resistant Cu/B/Ca/Al2O3 catalysts for durable hydrogenation of sec-butyl acetate to 2-butanol and ethanol

Peiyong Sun,Haixing Wang,Xueqing Luo,Changbin Jia,Shenghong Zhang,Zhilong Yao 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.74 No.-

Quaternary Cu/B/Ca/Al2O3 catalyst extrudates were prepared and optimized for hydrogenation of secbutylacetate (SBA) to 2-butanol and ethanol. The rationally designed catalyst with a B/Cu molar ratio of3/1 exhibited an extraordinary resistance to Cu sintering during the reaction over 1000 h, due to theenhanced interaction by B2O3 between copper species and support. The slight loss in activity after thelong-term test, caused mainly by the partial transformation of surface CaO to calcium acetate, could beeasily recovered by calcination and the following reduction treatments, rendering it feasible to apply thecatalyst to the industrial hydrogenation of SBA.

Comparative transcript profiling and cytological observation of the newly bred recessive genic male sterility non‑heading Chinese cabbage (Brassica rapa ssp. chinensis) line WS24‑3A

Liping Song,Xia Li,Feng Zu,Changbin Gao,Bincai Wang,Chufa Lin,Jinxing Tu,Aihua Wang,Guolin Zhou 한국유전학회 2019 Genes & Genomics Vol.41 No.12

Background WS24-3A is a newly bred non-heading Chinese cabbage genic male-sterile line, in which sterility is controlled by a recessive gene, designated as Bra2ms. WS24-3A has been used for hybrid breeding. Objective To reveal the underlying molecular mechanisms responsible for the sterility of WS24-3A. Methods Cytological observation of the process of sterile/fertile anther development was performed to determine the tissue and stage in which sterility occurs. Phenotyping and transcriptomic analyses were performed to identify differentially expressed genes (DEGs) between sterile and fertile flower buds at different stages. Results Cytological analysis revealed no tetrads at stage 7 or at later stages of anther development, and the degradation of callose was delayed. Abnormal meiocytes were surrounded by sustaining callose that degenerated gradually in WS24-3A. Comparative transcript profiling identified 3282 DEGs during three anther developmental stages, namely, pre-meiotic anther, meiotic anther, and anthers with single-celled pollen stage. The difference in DEG percentage between up-regulated and down-regulated at meiotic anther stage was obviously larger than at the other two stages; further, most DEGs are important for male meiosis, callose synthesis and dissolution, and tapetum development. Ten DEGs were found to be involved in anther and pollen development, which were analyzed by quantitative PCR. Conclusion Bra2ms affected gene expression in meiocytes and associated with callose synthesis, degradation and tapetum development. Our results provide clues to elucidate the molecular mechanism of genic male sterility in non-heading Chinese cabbage.

Video Object Segmentation with Weakly Temporal Information

( Yikun Zhang ),( Rui Yao ),( Qingnan Jiang ),( Changbin Zhang ),( Shi Wang ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.3

Video object segmentation is a significant task in computer vision, but its performance is not very satisfactory. A method of video object segmentation using weakly temporal information is presented in this paper. Motivated by the phenomenon in reality that the motion of the object is a continuous and smooth process and the appearance of the object does not change much between adjacent frames in the video sequences, we use a feed-forward architecture with motion estimation to predict the mask of the current frame. We extend an additional mask channel for the previous frame segmentation result. The mask of the previous frame is treated as the input of the expanded channel after processing, and then we extract the temporal feature of the object and fuse it with other feature maps to generate the final mask. In addition, we introduce multi-mask guidance to improve the stability of the model. Moreover, we enhance segmentation performance by further training with the masks already obtained. Experiments show that our method achieves competitive results on DAVIS-2016 on single object segmentation compared to some state-of-the-art algorithms.