Evaluation of roof cutting by directionally single cracking technique in automatic roadway formation for thick coal seam mining

Automatic roadway formation by roof cutting is a sustainable nonpillar mining method that has the potential to increase coal recovery,reduce roadway excavation and improve mining safety.In this method,roof cutting is the key process for stress relief,which significantly affects the stability of the formed roadway.This paper presents a directionally single cracking(DSC)technique for roof cutting with considerations of rock properties.The mechanism of the DSC technique was investi-gated by explicit finite element analyses.The DSC technique and roof cutting parameters were evaluated by discrete element simulation and field experiment.On this basis,the optimized DSC technique was tested in the field.The results indicate that the DSC technique could effectively control the blast-induced stress distribution and crack propagation in the roof rock,thus,achieve directionally single cracking on the roadway roof.The DsC technique for roof cutting with optimized parameters could effectively reduce the deformation and improve the stability of the formed roadway.Field engineering application verified the feasibility and effectiveness of the evaluated DSC technique for roof cutting.

COVID-19 Related Research by Data Mining in Single Cell Transcriptome Profiles

The outbreak of coronavirus disease 2019(COVID-2019)has drawn public attention all over the world.As a newly emerging area,single cell sequencing also exerts its power in the battle over the epidemic.In this review,the up-to-date knowledge of COVID-19 and its receptor is summarized,followed by a collection of the mining of single cell transcriptome profiling data for the information in aspects of the vulnerable cell types in humans and the potential mechanisms of the disease.

Research into comprehensive gas extraction technology of single coal seams with low permeability in the Jiaozuo coal mining area

For a low permeability single coal seam prone to gas outbursts,pre-drainage of gas is difficult and inefficient,seriously restricting the safety and efficiency of production.Radical measures of increasing gas extraction efficiency are pressure relief and infrared antirefiection.We have analyzed the effect of mining conditions and the regularity of mine pressure distribution in front of the working face of a major coal mine of the Jiaozuo Industrial(Group) Co.as our test area,studied the width of the depressurization zone in slice mining and analyzed gas efficiency and fast drainage in the advanced stress relaxation zone.On that basis,we further investigated and practiced the exploitation technology of shallow drilling,fan drilling and grid shape drilling at the working face.Practice and our results show that the stress relaxation zone is the ideal region for quick and efflcient extraction of gas.By means of an integrated extraction technology,the amount of gas emitted into the zone was greatly reduced,while the risk of dangerous outbursts of coal and gas was lowered markedly.This exploration provides a new way to control for gas in working faces of coal mines with low permeability and risk of gas outbursts of single coal seams in the Jiaozuo mining area.

Dynamic Analysis of the Seafloor Pilot Miner Based on Single-Body Vehicle Model and Discretized Track-Terrain Interaction Model

In order to achieve the complex dynamic analysis of the self-propelled seafloor pilot miner moving on the seafloor of extremely cohesive soft soil and further to make it possible to integrate the miner system with some subsystems to form the complete integrated deep ocean mining pilot system and perform dynamic analysis, a new method for the dynamic modeling and analysis of the miner is proposed and developed in this paper, resulting in a simplified 3D single-body vehicle model with three translational and three rotational degrees of freedom, while the track-terrain interaction model is built by partitioning the track-terrain interface into discrete elements with parameterized force dements built on the theory of terramechanics acting on each discrete dement. To evaluate and verify the correctness and effectiveness of this new modeling and analysis method, typical comparative studies with regard to computational efficiency and solution accuracy are carried out between the traditional modeling method of building the tracked vehicle as a multi-body model and the new modeling method. In full consideration of the particMar structure design of the pilot miner, the special characteristics of the seafioor soil and the hydrodynamic force of near-seafloor currnt, the dynamic simulation analysis of the miner is performed and discussed, which can provide useful guidance and reference for the practical miner system in design and operation. This new method can not only realize the rapid dynamic simulation analysis of the miner but also make possible the integration and rapid dynamic analysis of the complete integrated deep ocean mining pilot system in further researches.

Theoretical design and dynamic simulation of new mining paths of tracked miner on deep seafloor

With comprehensive considerations of the operational safety and collection efficiency for the tracked miner collecting the seafloor poly-metallic nodules, two new improved mining paths for the miner on the deep seafloor were proposed. Compared to the conventional mining path, the design principles and superiorities of the two new paths are that the miner turning with relative long radius should avoid large sinkage and high slip, so as to ensure its operational safety, while the space between its straight-line trajectories before and after the turning is optimum, which is designed as the total width of the miner, and collect nodules as more as possible, so as to ensure its collection efficiency. To realize the new mining paths, theoretical designs and quantitative calculations were carried out to determine the exact positions for the speed controls of the miner during its whole operation process. With the new dynamic model of the miner, and through regulations of the speeds of the left and right tracks of the miner on the exact motion positions according to the theoretical calculations, the two new improved mining paths for the miner on the seafloor were successfully simulated, thus the turning radius of the miner in the simulation is about 21.8 m, while the distance between the straight-line trajectories before and after the turning is about 5.2 m. The dynamic simulation results preliminarily prove the feasibility of these two new mining paths, and further can provide important theoretical guidance and useful technical reference for the practical tracked miner operation and control on the seafloor.

图计算体系结构和系统软件关键技术综述

图计算作为分析事物之间关联关系的重要工具,近年来已成为各国政府及公司争夺的关键技术.学术界和工业界在图计算体系结构和系统软件关键技术方面取得了一定进展.然而,现实场景图计算大多具有动态变化、应用需求复杂多样等特征.这给图计算在基础理论、体系架构和系统软件关键技术方面提出了新的需求,同时也带来了新的挑战.为应对这些挑战,科研人员提出了一系列图计算系统或图计算加速器,通过高性能计算、并行计算等技术来优化图计算过程.综述国内外图计算体系结构和系统软件关键技术的研究发展现状,对国内外研究的最新进展进行归纳、比较和分析,并结合国家发展战略和重大应用需求,选取与我国国计民生密切相关的领域,从典型应用分析总结图计算相关技术的行业进展.最后,就未来的技术挑战和研究方向进行展望.

基于直线段检测和LT描述符的矿井图像线特征匹配算法

图像匹配是同步定位与地图构建(SLAM)技术中极为重要的一环,用于根据图像之间的变换关系确定相机位姿。基于线特征的图像匹配方法具有较强的鲁棒性和抗噪能力,更加适用于井下图像匹配,基于深度学习的线描述符对线段遮挡等场景具有较高的鲁棒性,性能优于传统描述符,但卷积神经网络架构的描述符将可变长度线段抽象为固定维进行描述,不利于线段长度及视差变化较大图像的匹配。针对上述问题,提出一种基于直线段检测和线描述符的矿井图像线特征匹配算法。在频域利用单参数同态滤波降低图像的照射分量,并增强反射分量,提升亮度及对比度;在YUV空间利用对比度受限的自适应直方图均衡化(CLAHE)算法对亮度分量进行均衡,使亮度分布更加均匀;变换至RGB空间提取直线段检测(LSD)线,引入一种基于Transformer架构的LT描述符构建LSD线的特征向量,最后完成线特征匹配。实验结果表明:该算法结合了同态滤波和CLAHE算法的优点,增强后图像的亮度适中,对比度良好,灰度分布均匀,增强效果优于单参数同态滤波算法、EnlightenGAN算法;该算法提取的线特征数较原图平均提升了32.92%,在不同相似纹理占比、不同程度旋转与平移变化的井下图像匹配中鲁棒性好,平均正确匹配数为61.75对,平均精度为86.83%,优于线二进制描述符(LBD)算法、LBD_NNDR算法、LT算法,能够满足矿井图像稳健匹配的需求。

单细胞测序及其在动物繁殖机理研究中的作用

单细胞测序是一种基于单个细胞层面上获取自身细胞全部遗传信息的高通量测序技术,揭示了单个细胞的细胞内动力学,并通过数百万个细胞的高维目录回答生物学问题,包括基因组学、转录组学、染色质可及性、表观基因组学和跨物种的蛋白质组学数据。在动物繁殖机理研究中,单细胞测序技术以单细胞分辨率破译细胞和分子景观的强大能力成为了一种重要科研工具,对解决动物繁殖过程中相关细胞的分类、细胞间互作关系、细胞间通讯联系、繁殖关键基因挖掘等科学问题有重要意义,极大地改变了人们对动物繁殖过程中细胞内生物学和动力学特征的见解。作者简要介绍了单细胞测序的原理和3种测序类型,并总结了其在动物生殖生理学研究中的作用,旨在为后续的研究工作提供理论依据。

急倾斜中厚煤层单一巷道放顶煤采煤方法研究与应用

为解决某矿急倾斜中厚煤层倾角及厚度变化大的开采问题,提出了“急倾斜中厚煤层单一巷道放顶煤采煤方法”。该采煤方法是沿急倾斜煤层倾斜方向划分为若干区段,每个区段沿急倾斜煤层走向仅布置1条巷道。此巷道服务于1个采煤区段,担负工作面通风、运输和行人等任务。对单一巷道放顶煤采煤方法的巷道布置、综放工艺和沿空留巷方法进行了探讨。实践表明,该采煤方法使采煤工作面形成全负压通风,避免了巷道与采空区窜风,杜绝了采空区瓦斯积聚和遗煤自燃,实现了采煤机械化,提高了急倾斜中厚煤层的开采效率和煤炭回收率。单一巷道放顶煤采煤法为类似急倾斜煤层安全、高效开采提供了技术支撑。

单线激光雷达与测距仪耦合的移动式仓储存量盘点装备研发与应用

提升矿山信息化测绘水平是建设智能矿山的重要基础。选厂是矿产管理的主要场所,及时、精准掌握选厂的仓储存量对于矿山生产规划具有重要意义。然而,受限于作业环境和人员不可达等问题,传统地面测量方法难以有效采集仓储矿堆的完备点位信息,导致盘点结果精度差、效率低。为此,将垂向扫描的单线激光雷达与水平测距仪进行耦合,自主研发了一套单线激光雷达与测距仪耦合的移动式仓储存量盘点装备。该装备具备三维点云采集、数字表面模型构建、矿堆方量核算一体化在线处理功能,并可根据实际需求灵活拓展硬件集成方式,同时支持开发可视化等功能。以紫金山金铜矿选厂为研究区,进行了铜、硫精矿存量盘点试验,结果表明:所研发的装备可以实现选厂矿堆方量在线盘点,其重复盘点结果的一致性优于99%,与地磅称重盘点结果的比对精度优于99%,扫描点云质量和数据处理效率优于GEO-SLAM等进口移动式三维扫描设备。研发成果可拓展应用到露天采场剥离量验收、露天采场爆破程度分析、矿车载运量无人值守在线盘点等矿山信息化测绘方面,对于实现“减人增效”目标,助力智能矿山建设具有重要意义。

基于《中华人民共和国药典》《中药学》挖掘单味降糖中药

目的通过数据挖掘分析具有降糖作用的单味中药,为临床遣药组方和降血糖中药筛选提供理论依据。方法基于2020年版《中华人民共和国药典》(一部)结合《中药学(3版)》收载的治疗糖尿病或有降血糖作用的单味中药,通过Adobe Acrobat DC和Microsoft Excel 2016对其进行性、味、归经和功效的统计、归类、分析。结果在筛选出具有治疗消渴或糖尿病或降血糖作用的208味中药当中,以补虚药和清热药为主,且补虚药当中以补气药、温阳药和滋阴药居多,也会涉及活血化瘀、利水渗湿等药;归经上,以肝、肺、脾(胃)、肾经所占比重较大;药味上以苦、甘、辛为主;药性以寒、温、平居多。结论研究通过数据挖掘分析了单味降糖中药的共性及潜在规律,为临床糖尿病的辨证治疗和新药研究提供参考。

电子监控部分遮挡目标单模态自监督信息挖掘技术

针对电子监控视频中受遮挡目标识别难度高的问题,提出一种电子监控部分遮挡目标单模态自监督信息挖掘技术。为了得到目标的状态信息,利用遮挡检测方法判断监控视频中是否存在部分遮挡目标。当监控视频存在部分遮挡目标时,利用减法聚类方法进行特定目标的识别、跟踪或描述,并提供更准确和详细的目标特征信息。在此基础上,将交叉熵损失函数与软间隔三元组损失函数构建的监督遮挡目标特征学习判别损失函数作为部分遮挡目标信息挖掘的目标函数,在每个批次的电子监控样本中,搜寻最小距离的负样本对以及最大距离的正样本对,并通过反向传播优化参数。由此输入电子监控图像样本,通过前向传播输出得到电子监控部分遮挡目标单模态自监督信息挖掘结果。实验结果表明,所提出的技术可以有效挖掘电子监控部分遮挡目标,目标挖掘的mAP值高于0.9,能够为提升监控目标识别精度提供可靠依据。

基于单片机的煤矿安全监测系统设计

为更好的保障矿井安全生产,有效防范各类瓦斯爆炸事故,以AT89C51型单片机为核心组件,设计了一种煤矿安全监测系统,介绍了系统的整体结构,设计了系统的硬件部分与软件部分,并进行了应用仿真,取得了较好的应用效果,结果表明:该系统借助传感器可有效监测采集空气中的甲烷、烟雾的浓度及温度、湿度等情况,经单片机处理采集到数据后,可在LCD 1604显示屏上显示相关数据,当所采集的数据比设定值大时,会发出声光报警,及时提醒工作人员,可达到更好的保障矿井安全生产的目的。

基于模糊单神经元PI的煤矿电气设备电源频率自动化控制系统

为确保煤矿电气设备电源频率不偏离标准频率,保障煤矿电气设备安全稳定运行,设计基于模糊单神经元PI的煤矿电气设备电源频率自动化控制系统。数据采集层通过电源频率信号输出检测仪,采集电源频率数据,并使用改进小波阈值法,去噪频率数据,然后由数据传输层发送其至控制中心,控制中心在接收该数据的同时,由理想电源频率求解模块,通过多元回归模型预测电源理想频率,而后模糊神经元PI控制模块以实际、理想电源频率为输入,经频率偏差求解、模糊化等操作,获得控制信号,控制电源频率无线接近理想值。实验结果表明,该系统可实现煤矿电气设备电源频率自动化控制,控制设备电源频率无线接近理想值,电源频率控制效果显著。

赣南废弃离子型稀土矿区稻米重金属污染评价

江西赣州的离子型稀土资源丰富,已开发利用数十载,遗留下了300多处废弃离子型稀土矿区,其中以池浸堆浸工艺开采者居多。一些废弃矿区已有居民迁入,有必要对该区域的重金属污染问题及存在的健康风险进行评价。以废弃青山子矿区为例,测定矿区稻米样品中的重金属含量,并采用单因子污染指数法和内梅罗综合污染指数法对矿区稻米的重金属污染状况进行评价,然后采用美国环保局(USEPA)推荐的风险暴露模型评价食用矿区稻米对成人及儿童造成的健康风险,结果表明,废弃矿区稻米中主要重金属Cd、Pb、As、Zn、Cu的平均质量分数分别为0.048、1.18、2.45、60.9、5.99 mg/kg,其中Cd和Cu的平均质量分数均低于相应的标准限值,Pb、As和Zn的平均质量分数均高于相应的标准限值;废弃矿区稻米基本未受重金属Hg、Cd和Cu污染,但受Pb重度污染,受As和Zn轻微污染,综合污染程度为重度污染;以废弃矿区产出的稻米为主食可能会对成人构成轻微致癌综合健康风险,对儿童构成轻微非致癌综合健康风险。

工作面超前支护预应力注浆锚索技术的研究应用

长平煤业五盘区5308首采工作面采用重型放顶煤工艺开采,由于埋深大、底板直接底为泥岩,单体支柱穿底,两顺槽超前巷道帮鼓、底鼓严重,传统的单体柱配金属梁超前支护形式不能满足安全高效生产需要,急需探讨科学有效的新型超前支护技术。基于此,提出以“预应力注浆锚索补强”为技术核心的回采巷道超前支护技术。结果证明,以“预应力注浆锚索补强”为技术核心的超前支护技术可变被动支护为主动支护,能够提高顶板整体强度,改善巷道围岩条件,创造了安全舒适的作业环境。

渣滓溪矿机械化盘区上向进路充填法工艺改进

渣滓溪矿为地下开采矿山,采用多段斜井联合开拓,矿区采矿方法主要为浅孔留矿法和削壁充填法以及正在试验的深部破碎厚大矿体机械化盘区上向进路充填法。该矿山试验初期存在掘采效率低、充填接顶效果差、支护工艺复杂成本高的问题。针对这些问题,通过改进炮孔布置和凿岩机构,提升回采效率;优化充填设施工程,提高充填接顶率;引进树脂纤维网和单体液压支柱用于支护,并进行工业试验,取得良好效果。

红外传感技术在矿井主绞车松绳二次保护中的运用探究

为满足矿井主绞车松绳二次保护需求,本文将在STC单片机基础上构建一套红外传感技术方案,文章在详细说明红外传感技术方案基础上,详细阐述了该装置应用效果。根据现场评估结果显示,本文介绍的矿井主绞车松绳二次保护系统具有良好的安全效益与社会效益,可最大限度上保证工作人员的生命安全,值得推广。

矿山供电系统单相接地故障区段定位方法

中性点非有效接地的矿山高压供电系统发生单相接地故障后,故障暂态过程交叉干扰严重,故障信号呈现出很强的非线性、非平稳性、高时变性和复杂性,故障定位难度很大。针对此难题,提出了一种基于分布散度的故障区段定位方法。首先,通过等效电路分析了故障特性,研究并采用Choi-Williams分布(Choi-Williams Distribution,CWD)时频能量谱克服故障信号中多频率成分交叉干扰。然后,采用改进KL散度表征故障区段上下游信号时频分布差异,处理上下游信号CWD时频能量谱中重叠部分,消除故障区段上下游信号相似成分的不利影响。在此基础上,借助零序电流信号CWD-KL散度构建了故障定位判据。最后,仿真测试与对比分析验证了所提方法的有效性与优越性。

Systematic principles of surrounding rock control in longwall mining within thick coal seams

Effective surrounding rock control is a prerequisite for realizing safe mining in underground coal mines.In the past three decades, longwall top-coal caving mining(LTCC) and single pass large height longwall mining(SPLL) found expanded usage in extracting thick coal seams in China. The two mining methods lead to large void space left behind the working face, which increases the difficulty in ground control.Longwall face failure is a common problem in both LTCC and SPLL mining. Such failure is conventionally attributed to low strength and high fracture intensity of the coal seam. However, the stiffness of main components included in the surrounding rock system also greatly influences longwall face stability.Correspondingly, surrounding rock system is developed for LTCC and SPLL faces in this paper. The conditions for simultaneous balance of roof structure and longwall face are put forward by taking the stiffness of coal seam, roof strata and hydraulic support into account. The safety factor of the longwall face is defined as the ratio between the ultimate bearing capacity and actual load imposed on the coal wall.The influences provided by coal strength, coal stiffness, roof stiffness, and hydraulic support stiffness,as well as the movement of roof structure are analyzed. Finally, the key elements dominating longwall face stability are identified for improving surrounding rock control effectiveness in LTCC and SPLL faces.