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Effects of the initiation position on the damage and fracture characteristics of linear-charge blasting in rock

International Journal of Minerals,Metallurgy and Materials 2024年第3期31卷 443-451页

作者： Chenxi Ding Renshu yang Xiao Guo Zhe Sui Chenglong Xiao liyun yang School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China School of Mechanics and Civil Engineering China University of Mining and Technology(Beijing)Beijing 100083China School of Mathematics and Physics University of Science and Technology BeijingBeijing 100083China State Key Lab of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

To study the effects of the initiation position on the damage and fracture characteristics of linear-charge blasting, blasting model experiments were conducted in this study using computed tomography scanning and three-dimensional reconstruction methods. The fractal damage theory was used to quantify the crack distribution and damage degree of sandstone specimens after blasting. The results showed that regardless of an inverse or top initiation, due to compression deformation and sliding frictional resistance, the plugging medium of the borehole is effective. The energy of the explosive gas near the top of the borehole is consumed. This affects the effective crushing of rocks near the top of the borehole, where the extent of damage to Sections Ⅰ and Ⅱ is less than that of Sections Ⅲ and Ⅳ. In addition, the analysis revealed that under conditions of top initiation, the reflected tensile damage of the rock at the free face of the top of the borehole and the compression deformation of the plug and friction consume more blasting energy, resulting in lower blasting energy efficiency for top initiation. As a result, the overall damage degree of the specimens in the top-initiation group was significantly smaller than that in the inverse-initiation group. Under conditions of inverse initiation, the blasting energy efficiency is greater, causing the specimen to experience greater damage. Therefore, in the engineering practice of rock tunnel cut blasting, to utilize blasting energy effectively and enhance the effects of rock fragmentation, using the inverse-initiation method is recommended. In addition, in three-dimensional(3D) rock blasting, the bottom of the borehole has obvious end effects under the conditions of inverse initiation, and the crack distribution at the bottom of the borehole is trumpet-shaped. The occurrence of an end effect in the 3D linear-charge blasting model experiment is related to the initiation position and the blocking condition.

关键词： blasting linear charge initiation position computed tomography three-dimensional reconstruction damage

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Effect of Blasting Stress Wave on Dynamic Crack Propagation

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工程与科学中的计算机建模(英文) 2024年第1期138卷 349-368页

作者： Huizhen Liu Duanying Wan Meng Wang Zheming Zhu liyun yang Key Laboratory for Old Bridge Detection&Reinforcement Technology of the Ministry of Transportation Beijing100088China School of Mechanics and Civil Engineering China University of Mining and TechnologyBeijing100083China MOE Key Laboratory of Deep Underground Science and Engineering School of Architecture and EnvironmentSichuan UniversityChengdu610065China

Stress waves affect the stress field at the crack tip and dominate the dynamic crack propagation.Therefore,evaluating the influence of blasting stress waves on the crack propagation behavior and the mechanical characteristics of crack propagation is of great significance for engineering blasting.In this study,ANSYS/LS-DYNA was used for blasting numerical simulation,in which the propagation characteristics of blasting stress waves and stress field distribution at the crack tip were closely observed.Moreover,ABAQUS was applied for simulating the crack propagation path and calculating dynamic stress intensity factors(DSIFs).The universal function was calculated by the fractalmethod.The results show that:the compressive wave causes the crack to close and the reflected tensile wave drives the crack to initiate and propagate,and failure mode is mainly tensile failure.The crack propagation velocity varies with time,which increases at first and then decreases,and the crack arrest occurs due to the attenuation of stress waves and dissipation of the blasting energy.In addition,crack arrest toughness is smaller than the crack initiation toughness,applied pressure waveforms(such as the peak pressure,duration,waveforms,wavelengths and loading rates)have a great influence on DSIFs.It is conducive to our deep understanding or the study of blasting stress waves dominated fracture,suggesting a broad reference for the further development of rock blasting in engineering practice.

关键词： Crack propagation blasting stress wave dynamic stress intensity factor pressure waveform numerical simulation

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TGA factors promote plant root growth by modulating redox homeostasis or response

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Journal of Integrative Plant Biology 2022年第8期64卷 1543-1559页

作者： Xiaochen Hu liyun yang Mengfei Ren Lin Liu Jing Fu Hongchang Cui State Key Laboratory of Crop Stress Biology for Arid Areas College of Life SciencesNorthwest A&F UniversityYangling 712100China Department of Biological Science Florida State UniversityTallahasseeFL 32306USA

To identify novel regulators of stem cell renewal,we mined an existing but little explored cell typespecific transcriptome dataset for the Arabidopsis root.A member of the TGA family of transcription factors,TGA8,was found to be specifically expressed in the quiescent center(QC).Mutation in TGA8 caused a subtle root growth phenotype,suggesting functional redundancy with other TGA members.Using a promoter::HGFP transgenic approach,we showed that all TGA factors were expressed in the root,albeit at different levels and with distinct spatial patterns.Mutant analyses revealed that all TGA factors examined contribute to root growth by promoting stem cell renewal,meristem activity,and cell elongation.Combining transcriptome analyses,histochemical assays,and physiological tests,we demonstrated that functional redundancy exists among members of cladesⅡandⅤor those in cladesⅠandⅢ.These two groups of TGA factors act differently,however,as their mutants responded to oxidative stress differently and quantitative reverse transcription polymerase chain reaction assays showed they regulate different sets of genes that are involved in redox homeostasis.Our study has thus uncovered a previously unrecognized broad role and a mechanistic explanation for TGA factors in root growth and development.

关键词： Arabidopsis thaliana quiescent center reactive oxygen species redox root apical meristem TGA family

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Theoretical and numerical studies of rock breaking mechanism by double disc cutters

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International Journal of Mining Science and Technology 2023年第7期33卷 815-828页

作者： Yiqiang Kang Renshu yang liyun yang Chengxiao Li Jun Chen Haonan Zhu Ning Liu School of Mechanics and Civil Engineering China University of Mining and TechnologyBeijing 100083China School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China China Coal No.3 Construction(Group)Co. Ltd.Hefei 230000China

A plane mechanical model of rock breaking process by double disc cutter at the center of the cutterhead is established based on contact mechanics to analyze the stress evolution in the rock broken by cutters with different spacings. A continuous-discontinuous coupling numerical method based on zero-thickness cohesive elements is developed to simulate rock breaking using double cutters. The process, mechanism,and characteristics of rock breaking are comprehensively analyzed from five aspects: peak force, breaking form, breaking efficiency, crack mode, and breaking degree. The results show that under the penetrating action of cutters, dense cores are formed due to shear failure under respective cutters. The tensile cracks propagate in the rock, and then rock chips form with increasing penetration depth. When the cutter spacing is increased from 10 to 80 mm, the peak force gradually increases, the rock breaking range increases first and then decreases, the specific energy decreases first and then rises, and the breaking coefficient of intermediate rock decreases from 0.955 to 0.788. The area of rock breaking is positively correlated with the length of the tensile crack. Furthermore, the length of the tensile crack accounts for 14.4%–33.6% of the total crack length.

关键词： Disc cutter spacing Mechanical model Indentation experiment Continuous-discontinuous numerical method Fractal dimension

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清至民国时期广西左江流域民间契约文书研究——以崇左市壮族博物馆新藏何村契约为中心

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农业考古 2024年第3期 97-104页

作者：杨丽云秦婕崇左市壮族博物馆桂林博物馆

何村契约以白契为主,其交易形式丰富,既有典当、转当、转租的活卖,又有永割的绝卖,具有高度格式化的特点,并呈现地域化特色。何村契约中包含的主要要件和缜密的文字表述,为交易双方提供了坚实的多重保障机制。何村契约整体反映了清代至... 详细信息

何村契约以白契为主,其交易形式丰富,既有典当、转当、转租的活卖,又有永割的绝卖,具有高度格式化的特点,并呈现地域化特色。何村契约中包含的主要要件和缜密的文字表述,为交易双方提供了坚实的多重保障机制。何村契约整体反映了清代至民国期间左江流域土地交易活跃、出现土地分化的特点,且处于村级土地交易市场范围,同时又展现了左江流域土地交易具有浓厚的宗族色彩和壮族特色。

关键词：何村契约左江流域白契土地交易

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Hydrothermal preparation of nanocrystalline ZnO_(2)

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Particuology 2012年第3期10卷 388-391页

作者： Guipeng Feng liyun yang Tianxi Wang Jiamin Zhang Tianjun Lou Department of Chemistry and Chemical Engineering Xinxiang UniversityXinxiang 453000China School of Chemistry and Chemical Engineering Henan Institute of Science and TechnologyXinxiang 453003China

A green hydrothermal method was proposed for the synthesis of nanocrystalline ZnO2, using Zns（CO3）2（OH）6 powder and 6vol% H2O2 aqueous solution as the starting materials. Characterization results from X-ray diffraction, Raman, high resolution transmission electron microscopy and selected area electron diffraction revealed that the products synthesized at 80-120 ℃ for 6-18 h were pure cubic phase ZnO2 nanocrystals. Room temperature photoluminescence spectra of the as-synthesized ZnO2 nanocrystals displayed a wide and strong emission band in the visible region of about 525-570 nm upon laser excitation at 325 nm, which may have originated from their surface state and other crystal defects.

关键词： Zinc peroxide Nanocrystals Semiconductors Hydrothermal synthesis Photoluminescence

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融合软考知识点的IT项目管理课程改革与实践

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福建电脑 2024年第2期40卷 121-124页

作者：杨莉云广州华商学院数据科学学院广东广州511300

针对IT项目管理课程理论性强、学生缺乏项目实践经验和教学效果不理想的问题,本文探讨将系统集成项目管理工程师考试知识点引入课程教学。通过完善教学内容、调整教学安排、建设线上教学资源、改革教学策略和教学模式等措施,提高课程教... 详细信息

针对IT项目管理课程理论性强、学生缺乏项目实践经验和教学效果不理想的问题,本文探讨将系统集成项目管理工程师考试知识点引入课程教学。通过完善教学内容、调整教学安排、建设线上教学资源、改革教学策略和教学模式等措施,提高课程教学效果。实践结果表明,该教学改革可有效提高学生的学习积极性,有利于提升学生的专业能力和就业竞争力。

关键词： IT项目管理专业技术资格考试课程改革

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预切缝位置及深度对SBM滚刀破岩的影响

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煤炭学报 2024年第1期49卷 415-425页

作者：杨仁树康一强杨立云刘康丁晨曦樊谨豪中国矿业大学(北京)力学与土木工程学院北京100083 北京科技大学土木与资源工程学院北京100083

利用水射流对岩体进行预切缝是提高竖井全断面掘进机破岩效率、实现深部资源机械化开发的关键技术。针对预切缝位置及深度合理参数选取的难题,首先指出了锥面刀盘带动下滚刀破岩的工况特征,进而基于Cohesive单元方法,建立了预切缝条件... 详细信息

利用水射流对岩体进行预切缝是提高竖井全断面掘进机破岩效率、实现深部资源机械化开发的关键技术。针对预切缝位置及深度合理参数选取的难题,首先指出了锥面刀盘带动下滚刀破岩的工况特征,进而基于Cohesive单元方法,建立了预切缝条件下的滚刀破岩离散-连续耦合数值模型。以完整岩体为对照组,对比分析了不同预切缝距离和深度对滚刀破岩的受力特征和岩石破碎特征的影响规律。阐述了预切缝条件下,滚刀破岩时密实核形成、块状岩渣形成、Hertz裂纹扩展3个阶段性特征,指出了岩体的非对称破碎特性和不同区域岩渣的形成机制。最终从滚刀受力、破岩面积、破岩比能耗、岩渣破碎程度4个方面综合分析,确定了预切缝的最佳距离和深度取值范围。研究结果表明:预切缝可以显著减小竖井全断面掘进机滚刀破岩过程中的贯入力和侧向力。与完整岩体相比,贯入力峰值降低了44.0%~10.3%。侧向力峰值降低了35.2%~6.5%。预切缝间距及深度较小时,会限制滚刀破岩范围,同时使得破碎岩体块度更小,导致破岩比能耗增高。随着预切缝深度的增大,破岩体积先增大后趋于稳定,比能耗先减小后保持不变。最终,确定了切缝距离为70~90 mm,深度为60~80 mm时破岩效果最佳,破岩体积较无切缝时提高约1倍,破岩比能耗降低69.2%。研究结果为刀盘辅助破岩装备的设计及参数确定提供了参考。

关键词：预切缝滚刀破岩分形维数竖井全断面掘进机

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基于迁移学习的非结构化大数据缺失值插补算法

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吉林大学学报（信息科学版） 2024年第2期42卷 372-377页

作者：颜远海杨莉云广州华商学院数据科学学院广东增城511300

针对数字信息产生的海量、多角度的非结构化大数据,由于外界干扰、数据结构损坏等因素造成其信息丢失问题,提出了基于迁移学习的非结构化大数据缺失值插补算法。通过迁移学习算法,预测非结构化大数据缺失部位,利用朴素贝叶斯算法分类数... 详细信息

针对数字信息产生的海量、多角度的非结构化大数据,由于外界干扰、数据结构损坏等因素造成其信息丢失问题,提出了基于迁移学习的非结构化大数据缺失值插补算法。通过迁移学习算法,预测非结构化大数据缺失部位,利用朴素贝叶斯算法分类数据特征,度量属性间权重值,明确数据类别特征差异向量,辨别特征差异程度。采用核回归模型对数据缺失部分实施非线性映射,经过多项式变化编码,描述数据的跨空间互补条件,完成非结构化大数据缺失值插补。实验结果表明,所提算法可以有效完成非结构化大数据缺失值插补,具有较好的插补效果,能提高插补精度。

关键词：迁移学习非结构化大数据缺失值插补缺失值预测核回归函数

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振腹对幼龄厌食模型大鼠外周血中胃肠激素及胃肠动力的影响

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Journal of Acupuncture and Tuina Science 2024年第2期22卷 104-110页

作者：周玲张岩谷楠白卫杰杨丽芸李进龙杨燕萍(翻译) Hebei University of Chinese Medicine Shijiazhuang 050200China Hebei Province Special Care Hospital Shijiazhuang 050051China The Third Hospital of Shijiazhuang Hebei ProvinceShijiazhuang 050011China 不详

目的:观察振腹对厌食症模型大鼠的治疗作用及对其外周血中八肽胆囊收缩素(CCK-8)和胃动素(MTL)含量的影响。方法:按照随机数字表法将40只幼龄大鼠进行分组,分为正常组10只和造模组30只。正常组给予普通饲料喂食。造模组采用病因模拟法... 详细信息

目的:观察振腹对厌食症模型大鼠的治疗作用及对其外周血中八肽胆囊收缩素(CCK-8)和胃动素(MTL)含量的影响。方法:按照随机数字表法将40只幼龄大鼠进行分组,分为正常组10只和造模组30只。正常组给予普通饲料喂食。造模组采用病因模拟法构建厌食症模型,造模3周后将其随机分为药物组、振腹组和模型组,每组10只。药物组按0.72 g/(kg·bw)剂量给予健胃消食片灌胃(将0.72 g药物用纯水配制成10 mL药液);正常组和模型组每天上午灌服等体积纯水1次;振腹组予以振腹治疗,每日1次,共治疗21次。检测各组大鼠体质量、摄食量、外周血CCK-8、MTL、胃泌素(GAS)及神经降压素(NT)的含量和小肠推进率。结果:与模型组相比,振腹组与药物组的体质量和摄食量、血清MTL及GAS含量和小肠推进率明显提高,血浆CCK-8、NT含量及胃残留率降低,差异具有统计学意义(P0.05)。结论:振腹可增加厌食症模型大鼠的进食量和体质量,减少胃内容物的残留,提高小肠推进率,对厌食症具有较好的治疗作用。其作用机理可能与抑制血浆CCK-8和NT分泌,促进血清MTL和GAS释放有关。

关键词：推拿按摩腹部振法胃动素八肽胆囊收缩素厌食症大鼠

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