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A numerical simulation study on mechanical behaviour of coal with bedding planes under coupled static and dynamic load

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International Journal of Mining Science and Technology 2018年第5期28卷 791-797页

作者： Lihai Tan Ting Ren xiaohan yang Xueqiu He School of Civil Mining and Environmental Engineering University of Wollongong School of Resources and Safety Engineering Central South University School of Civil and Environmental Engineering University of Science and TechnologyBeijing

To investigate the bedding influence on coal mechanical behaviour in underground environments such as coal or rock burst, simulations of dynamic SHPB tests of pre-stressed coal specimens with different bedding angles were carried out using a particle flow code 2-dimensional(PFC2D). Three impact velocities of 4, 8 and 12 m/s were selected to study dynamic behaviours of coal containing bedding planes under different dynamic loads. The simulation results showed that the existence of bedding planes leads to the degradation of the mechanical properties and their weakening effect significantly depends on the angle h between the bedding planes and load direction. With h increaseing from 0° to 90°, the strength first decreased and subsequently increased and specimens became most vulnerable when h was 30° or 45°.Five failure modes were observed in the specimens in the context of macro-cracks. Furthermore, energy characteristics combined with ultimate failure patterns revealed that maximum accumulated energy and failure intensity have a positive relation with the strength of specimen. When bedding planes were parallel or perpendicular to loading direction, specimens absorbed more energy and experienced more violent failure with increased number of cracks. In contrast, bedding planes with h of 30° or 45° reduced the specimens' ability of storing strain energy to the lowest with fewer cracks observed after failure.

关键词： Static–dynamic coupled loads SHPB Coal bedding angle Strain energy PFC2D

Developing coal burst propensity index method for Australian coal mines

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International Journal of Mining Science and Technology 2018年第5期28卷 783-790页

作者： xiaohan yang Ting Ren Lihai Tan Alex Remennikov Xueqiu He School of Civil Mining and Environmental Engineering University of Wollongong Centre of Infrastructure Protection and Mining Safety University of Wollongong School of Civil and Environmental Engineering University of Science and TechnologyBeijing

Coal burst is the violent failure of overstressed coal, and it is often accompanied by sound, coal ejection and seismic events. It is subsequently recognized as a serious safety risk of Australia after double fatalities coal burst happened at Austar Coal Mine. Considering the increasing trend of coal burst severity and frequency with mining depth, it is an urgent task to develop the coal burst risk assessment methods for Australia underground coal mines. Coal burst propensity index method is a widely used method of burst risk evaluation of coal as it is summed up from the coal burst research and practice of many *** paper presents the experimental and theoretical research of coal burst propensity index method for coal burst risk assessment in Australia. The definition of four indexes including elastic strain energy index(W_(ET)), bursting energy index(K_E), dynamic failure time(DT) and uniaxial compression strength(RC)is introduced in the first part. Then, the standard laboratory test process and test parameter of coal burst propensity index is presented. DT test is conducted with 0.3 mm/min displacement control loading rate while other test is with 0.5 mm/min. Besides, modified data processing and risk classification method of test are proposed. Differentiate analysis of stress-strain curve is adopted in the data processing of DT and KEindex. A four level risk classification form of burst risk is recommended for Australian underground coal mines. Finally, two likely improvement methods of W_(ET) test, including volumetric strain indicator method and theoretical calculation method, are discussed.

关键词： Coal burst Coal burst propensity Risk evaluation Underground mining

Abscisic Acid Receptors:Past,Present and Future

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Journal of Integrative Plant Biology 2011年第6期53卷 469-479页

作者： Jianjun Guo xiaohan yang David J. Weston Jin-Gui Chen Department of Genetics Harvard Medical School Boston Massachusetts 02114-2790 USA Department of Molecular Biology Massachusetts General Hospital Boston Massachusetts 02114-2790 USA Biosciences Division Oak Ridge National Laboratory Oak Ridge TN 37831-6422 USA

acid （ABA） is the key plant stress hormone. Consistent with the earlier studies in support of the presence of both membrane- and cytoplasm-localized ABA receptors, recent studies have identified multi- ple ABA receptors located in various subcellular locations. These include a chloroplast envelope-localized receptor （the H subunit of Chloro- plast Mg2＋-chelatase/ABA Receptor）, two plasma membrane-localized receptors （G-protein Coupled Receptor 2 and GPCR-type G proteins）, and one cytosol/nucleus-localized Pyrabactin Resistant （PYR）/PYR-Like （PYL）/Regulatory Component of ABA Receptor 1 （RCAR）. Although the downstream molecular events for most of the identified ABA receptors are currently unknown, one of them, PYR/PYL/RCAR was found to directly bind and regulate the activity of a long-known central regulator of ABA signaling, the A-group protein phosphatase 2C （PP2C）. Together with the Sucrose Non-fermentation Kinase Subfamily 2 （SnRK2s） protein kinases, a central signaling complex （ABA-PYR-PP2Cs-SnRK2s） that is responsible for ABA signal perception and transduction is supported by abundant genetic, physiological, biochemical and structural evidence. The identification of multiple ABA receptors has advanced our understanding of ABA signal perception and transduction while adding an extra layer of complexity.

关键词： ABA ChlH/ABAPJCCH/GUN5 FCA GCR2 GTGIlGTG2 PYLIPYL/RCAR.

Fracture features of brittle coal under uniaxial and cyclic compression loads

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International Journal of Coal Science & Technology 2023年第1期10卷 60-72页

作者： Shikang Song Ting Ren Linming Dou Jian Sun xiaohan yang Lihai Tan Shaanxi Zhengtong Coal Industry Co. Ltd.Xianyang 713600China School of Civil Mining and Environmental EngineeringUniversity of WollongongWollongong 2522Australia State Key Laboratory of Coal Resources and SafeMining China University of Mining and TechnologyXuzhou 221116China School of Energy and Safety Engineering Anhui Universityof Science and TechnologyHuainan 232001China School of Civil Engineering The University of QueenslandBrisbane 4072Australia

Under the efects of complex geological and stress environments,burst hazards continue to be a major challenge for underground space utilization and deep resources exploration as its occurrence can lead to personnel causalities,equipment damage and structural *** the stress path experienced by in-situ coal body,cyclic loading appears in quite various forms for instance shearer cutting,overlying strata breakage,hydro-fracturing and blasting,during tunnel,mining and underground space utilizing *** stability of the underground coal body subject to periodic loading/unloading stress is extremely important for maintain the function of designed engineering structure for waste storage,safe mining,roadway development,gas recovery,carbon sequestration and so *** mechanical properties of hard rock subject to cyclic fatigue loads has been intensively investigated by many researchers as the rock burst induced by supercritical loads has long been a safety risk and engineering problems for civil and tunneling engineering under deep *** recently,the mechanical properties of coal samples under cyclic fatigue loads is investigated from the aspect of hysteresis,energy dissipation and irreversible damage as the burst hazards of brittle coal is rising in many ***,the crack propagation and fracture pattern of brittle coal need more research to understand the micro mechanism of burst incubation subject to cyclic fatigue loads as brittle coal can store more elastic strain energy and rapidly release the energy when its ultimate strength once *** research studied the internal crack status corresponding to diferent cyclic fatigue loading stage of brittle coal *** AE monitoring was applied during the uniaxial and cyclic loading process of brittle coal samples to record the crack intensity of samples at diferent loading *** damage evolution curve corresponding to loading status was then *** fracture pattern

关键词： Fracture Crack Coal burst Acoustic emission Computed tomography

Multi-scale pore fractal characteristics of differently ranked coal and its impact on gas adsorption

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International Journal of Mining Science and Technology 2023年第4期33卷 389-401页

作者： Zhongbei Li Ting Ren Xiangchun Li Ming Qiao xiaohan yang Lihai Tan Baisheng Nie School of Civil MiningEnvironmental and Architectural EngineeringUniversity of WollongongNew South Wales 2522Australia School of Safety Engineering China University of Mining and TechnologyXuzhou 221116China School of Emergency Management and Safety Engineering China University of Mining and Technology-BeijingBeijing 100083China State Key Laboratory of Coal Mine Disaster Dynamics and Control School of Resources and Safety EngineeringChongqing UniversityChongqing 400044China

Well-developed pores and cracks in coal reservoirs are the main venues for gas storage and *** investigate the multi-scale pore fractal characteristics,six coal samples of different rankings were studied using high-pressure mercury injection(HPMI),low-pressure nitrogen adsorption(LPGA-N2),and scanning electron microscopy(SEM)test *** on the Frankel,Halsey and Hill(FHH)fractal theory,the Menger sponge model,Pores and Cracks Analysis System(PCAS),pore volume complexity(D_(v)),coal surface irregularity(Ds)and pore distribution heterogeneity(D_(p))were studied and evaluated,*** effect of three fractal dimensions on the gas adsorption ability was also analyzed with high-pressure isothermal gas adsorption *** show that pore structures within these coal samples have obvious fractal characteristics.A noticeable segmentation effect appears in the Dv1and Dv2fitting process,with the boundary size ranging from 36.00 to 182.95 nm,which helps differentiate diffusion pores and seepage *** D values show an asymmetric U-shaped trend as the coal metamorphism increases,demonstrating that coalification greatly affects the pore fractal *** three fractal dimensions can characterize the difference in coal microstructure and reflect their influence on gas adsorption *** volume(V_(L))has an evident and positive correlation with Dsvalues,whereas Langmuir pressure(P_(L))is mainly affected by the combined action of Dvand *** study will provide valuable knowledge for the appraisal of coal seam gas reservoirs of differently ranked coals.

关键词： Multi-scale pore structure Fractal theory Fractal characteristics Differently ranked coal Coalbed gas adsorption

Overfitting Reduction of Pose Estimation for Deep Learning Visual Odometry

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China Communications 2020年第6期17卷 196-210页

作者： xiaohan yang Xiaojuan Li Yong Guan Jiadong Song Rui Wang Information Engineering College Capital Normal UniversityBeijing 100048China Beijing Engineering Research Center of High Reliable Embedded System Beijing Advanced Innovation Center for Imaging Theory and Technology Machinery Industry Information Center Beijing 100823China Beijing Key Laboratory of Light Industrial Robots and Safety Verification

Error or drift is frequently produced in pose estimation based on geometric"feature detection and tracking"monocular visual odometry(VO)when the speed of camera movement exceeds 1.5 m/***,in most VO methods based on deep learning,weight factors are in the form of fixed values,which are easy to lead to overfitting.A new measurement system,for monocular visual odometry,named Deep Learning Visual Odometry(DLVO),is proposed based on neural *** this system,Convolutional Neural Network(CNN)is used to extract feature and perform feature ***,Recurrent Neural Network(RNN)is used for sequence modeling to estimate camera’s 6-dof *** of fixed weight values of CNN,Bayesian distribution of weight factors are introduced in order to effectively solve the problem of network *** 18,726 frame images in KITTI dataset are used for training *** system can increase the generalization ability of network model in prediction *** with original Recurrent Convolutional Neural Network(RCNN),our method can reduce the loss of test model by 5.33%.And it’s an effective method in improving the robustness of translation and rotation information than traditional VO methods.

关键词： visual odometry neural network pose estimation bayesian distribution overfitting

LDAS&ET-AD:Learnable Distillation Attack Strategies and Evolvable Teachers Adversarial Distillation

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Computers, Materials & Continua 2024年第5期79卷 2331-2359页

作者： Shuyi Li Hongchao Hu xiaohan yang Guozhen Cheng Wenyan Liu Wei Guo National Digital Switching System Engineering&Technological R&D Center The PLA Information Engineering UniversityZhengzhou450000China

Adversarial distillation(AD)has emerged as a potential solution to tackle the challenging optimization problem of loss with hard labels in adversarial ***,fixed sample-agnostic and student-egocentric attack strategies are unsuitable for ***,the reliability of guidance from static teachers diminishes as target models become more *** paper proposes an AD method called Learnable Distillation Attack Strategies and Evolvable Teachers Adversarial Distillation(LDAS&ET-AD).Firstly,a learnable distillation attack strategies generating mechanism is developed to automatically generate sample-dependent attack strategies tailored for distillation.A strategy model is introduced to produce attack strategies that enable adversarial examples(AEs)to be created in areas where the target model significantly diverges from the teachers by competing with the target model in minimizing or maximizing the AD ***,a teacher evolution strategy is introduced to enhance the reliability and effectiveness of knowledge in improving the generalization performance of the target *** calculating the experimentally updated target model’s validation performance on both clean samples and AEs,the impact of distillation from each training sample and AE on the target model’s generalization and robustness abilities is assessed to serve as feedback to fine-tune standard and robust teachers *** evaluate the performance of LDAS&ET-AD against different adversarial attacks on the CIFAR-10 and CIFAR-100 *** experimental results demonstrate that the proposed method achieves a robust precision of 45.39%and 42.63%against AutoAttack(AA)on the CIFAR-10 dataset for ResNet-18 and MobileNet-V2,respectively,marking an improvement of 2.31%and 3.49%over the baseline *** comparison to state-of-the-art adversarial defense techniques,our method surpasses Introspective Adversarial Distillation,the top-performing method in terms of robustne

关键词： Adversarial training adversarial distillation learnable distillation attack strategies teacher evolution strategy

New technologies accelerate the exploration of non-coding RNAs in horticultural plants

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Horticulture Research 2017年第1期4卷 219-226页

作者： Degao Liu Ritesh Mewalal Rongbin Hu Gerald A Tuskan xiaohan yang Biosciences Division Oak Ridge National LaboratoryOak Ridge37831-6422TNUSA

Non-coding RNAs(ncRNAs),that is,RNAs not translated into proteins,are crucial regulators of a variety of biological processes in *** protein-encoding genes have been relatively well-annotated in sequenced genomes,accounting for a small portion of the genome space in plants,the universe of plant ncRNAs is rapidly *** advances in experimental and computational technologies have generated a great momentum for discovery and functional characterization of *** we summarize the classification and known biological functions of plant ncRNAs,review the application of next-generation sequencing(NGS)technology and ribosome profiling technology to ncRNA discovery in horticultural plants and discuss the application of new technologies,especially the new genome-editing tool clustered regularly interspaced short palindromic repeat(CRISPR)/CRISPR-associated protein 9(Cas9)systems,to functional characterization of plant ncRNAs.

关键词： expanding universe momentum

Agrobacterium–mediated Transformation of Kalanchoe laxiflora

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Horticultural Plant Journal 2019年第5期5卷 221-228页

作者： Xiling Wang Xinlu Chen Qunkang Cheng Kaikai Zhu xiaohan yang Zongming Cheng Department of Plant Sciences University of TennesseeKnoxvilleTN37996USA College of Biotechnology Southwest UniversityChongqing400715China Department of Entomology and Plant Pathology University of TennesseeKnoxvilleTN37996USA College of Horticulture Nanjing Agricultural UniversityNanjing210095China Biosciences Division Oak Ridge National LaboratoryOak RidgeTN37831-6422USA

Plants with crassulacean acid metabolism(CAM) generally utilize water 20%–80% more efficiently than non-CAM plants. The whole genomes of several CAM plants have been sequenced or are being sequenced. For effective genome characterization and genome editing of CAM plants,an efficient transformation system is essential. In this study, we developed an Agrobacterium-mediated transformation protocol for Kalanchoe laxiflora, an obligate CAM plant,by optimizing several factors affecting the transformation efficiency. Agrobacterium strains AGL1, C58, EHA105,and GV3101 were all suitable for K. laxiflora transformation. Fifty-nine percent of the leaf explants yielded kanamycin-resistant and GUS-positive shoots. Polymerase chain reaction and quantitative real-time PCR(qRT-PCR) using gus A-, gus Plus-, npt II-and hpt-specific primers confirmed that the transgenes were integrated into K. laxiflora genome and expressed. This efficient transformation system will allow effective functional characterization of genes through over-or down-expression, knockout, or genome editing.

关键词： Kalanchoe laxiflora Agrobacterium-mediated transformation CAM plants