基于深度神经网络的露天矿岩石爆破效果预测

装载和运输成本占到露天矿运营总成本的50%以上,而爆破后岩石破碎程度直接影响到露天矿装载和运输成本。为了得到爆破参数和岩石破碎度之间的关系,收集了平朔东露天矿爆破参数和岩石破碎度数据,使用图像识别技术大规模收集分析爆破后岩块粒径分布,基于深度神经网络研究分析爆破参数和岩石破碎度之间的关系,建立了适用于东露天矿的爆破参数和破碎度的预测模型,并对爆破参数做敏感性分析,确立了炸药单耗和孔距是主要影响因素,并分别建立了炸药单耗和孔距与岩石破碎度之间的变化关系。研究结果可以指导矿山确定合理的穿孔和爆破参数以得到最佳的岩石破碎度,从而减少露天矿运营总成本。     

Analysis of strategies employed during upper extremity positioning actions

This article describes the study of motor actions associated with positioning of extremities. These actions are arm movements of varying positions. Studies of such motor actions are important due to various applications of these motions. In this article, positioning motor actions are observed from a systemic-structural activity theory point of view. Previous research studied positioning motor actions with two targets, this research considers not just two, but four targets. Results of this study created new data related to the properties of the regulation process for positioning actions as well as discovered new opportunities for using these discovered properties. The study of positioning actions has been conducted using a functional analysis approach of the activity when the activity is considered a self-regulative system. Action precision and error analysis are performed from the activity self-regulation viewpoint during this study. Findings support that not only cognitive but emotional-motivational mechanisms of activity regulation are important factors in error analysis. This aspect of error analysis cannot be reduced to studying performance under stress.     

水压冲击式凿岩机的噪声分析与试验研究

目前在矿山大量使用的气动凿岩机工作噪声高达125dB(A)，严重危害工人的身体健康，且长期得不到实质性改善；水压凿岩机具有气动凿岩机无法比拟的高效率、低噪声的性能优势，又有液(油)压凿岩机所不具备的结构简单、成本相对低廉的特点，因而适用于众多发展中国家特别是薄矿层开采和中，小巷道掘进。介绍了新型冲击式水压凿岩机的工作原理、结构形式、水压凿岩机噪声发生机制和控制措施以及水压凿岩机主要技术参数、性能测试数据及与风动凿岩机的对比情况结果表明：水压凿岩机工作噪声比风动凿岩机降低20dB(A)，凿岩速度在工作压力为11MPa时比气动凿岩机在0．5MPa风压时提高60％以上，具有明显的优势。     

Correlates of coal mine accidents and injuries: A literature review

Coal mining is the most dangerous occupation in the United States, with injury frequency and severity rates several times the average for all industries. Although mine safety improved slightly during the early 1970's, recent trends indicate small decreases in accidents and injuries and, in some cases, increases in accident severity. Experienced miners have lower risks of fatal injuries than inexperienced miners. Workers in small mines are more likely to receive fatal injuries than those in large mines. The various engineering methods of extracting coal from its natural deposit do not produce different fatality rates. The thickness of the coal seam mined is not related to the incidence of fatalities. Although conflicting evidence appears in the literature, recent studies find younger miners with much higher disabling injury rates than older miners. Whether a collective bargaining agreement is in effect is unrelated to accident and injury occurrence at a mine site. Studies of the relationships of accident and injuries to the effectiveness of safety training, the number of shifts each day at a mine site, and the time elapsed during a shift until an accident occurs have produced ambiguous results, often as a result of analysis of inadequate data.     

硬地层中新型PDC齿破岩机理及试验研究

随着油气开采不断向深部硬地层发展,常规PDC（polycrystalline diamond compact,聚晶金刚石复合片）钻头出现破岩速度慢、易损坏、效率低等问题,难以满足当下提速增效的钻井需求。PDC切削齿结构是提高PDC钻头破岩效率的关键因素,针对不同岩石地层进行不同结构切削齿的设计具有重大意义。针对深部硬地层钻井,设计了一种非平面结构的新型PDC齿,该PDC齿具有脊形切削结构且可分层破碎岩石。为掌握此新型PDC齿的破岩机理和各项性能,采用有限元仿真模拟与试验相结合的方法,开展了新型PDC齿与常规PDC齿破岩过程的对比研究。结果表明：新型PDC齿在水平方向、横向和纵向三个方向所受切削力的均值及波动幅度均较小,因此新型PDC齿在破岩过程中有更稳定的切削能力;新型PDC齿受剧烈磨损和冲击崩断的可能性更小,使用寿命更长,且具有更高的破岩效率。研究结果可为新型PDC齿的研发和推广提供理论依据,为PDC钻头在硬地层钻井过程中实现提速增效提供支撑。     

Towards an explanation of age-related difficulties in crossing a two-way street

Crossing a two-way street is a complex task that involves visual, cognitive and motor abilities, all of which are known to decline with ageing. In particular, older pedestrians may experience difficulties when crossing two-way streets because of incorrect gap acceptance choices and impossible or unperceived evasive actions. To understand the overrepresentation of older pedestrians in crash statistics, several experimental studies have sought to identify traffic-related factors as well as those related to the abilities of the individuals themselves. However, none of these studies has required participants to actually walk across an experimental two-way street with curbs, which is a particularly challenging situation for older pedestrians. To fill this research gap, a quasi-experiment was conducted in a simulator including a total of 58 healthy aged participants (25 younger-old [age 60–72] and 33 older-old [age 72–92]) and 25 young adults (aged 18–25 years). Participants carried out a street-crossing task in a simulated two-way traffic environment; curbs were present on both sides of the experimental street. Participants also undertook a battery of tests to assess their visual and cognitive abilities. In addition, during the experiment, the participants’ gait parameters were recorded. In line with earlier findings, the older-old group of participants made a higher number of decisions that led to collisions with approaching cars compared with the other groups. The two groups of older participants experienced specific difficulties when vehicles were in the far lane or when they approached rapidly. A regression analysis identified visual acuity, speed of processing (assessed using the UFOV^® test), and step length as significant predictors of collisions. Our results have implications for understanding the difficulties experienced by older pedestrians and allow to draw up several recommendations for improving their safety.     

混合式单牙轮钻头破岩性能研究

在石油钻探过程中,优质的钻头对于降低钻井成本和提高钻井效率至关重要。通过设计,将牙掌结构与牙轮结构相连接,并且分别在牙轮和牙掌上安装锥形齿和PDC齿,从而设计出一种新型的混合式单牙轮钻头。该混合式单牙轮钻头较一般单牙轮钻头多了PDC齿,利用冲击和剪切原理破岩。牙轮大端通过井底中心,所有齿圈与井壁接触,在破岩的同时可以起到保径作用。建立了混合式单牙轮钻头与岩石相互作用的有限元模型,并对钻头井底模型、牙齿主切削力和破岩体积进行了仿真分析。通过台架实验对数值模拟得到的钻压和进尺量进行验证。研究结果表明,数值模拟得到的钻压和进尺量与台架测试结果相符,破岩载荷规律与钻头结构设计特点一致。混合式单牙轮钻头与球形单牙轮钻头相比,侧向力减小39.6%,破岩效率提高37%。使用该混合式单牙轮钻头钻井时稳定性更高,可以减小井斜发生的概率。根据结果可知,数值模拟在研究该混合式单牙轮钻头破岩规律中是有效的,该方法为钻头进一步设计及其工作特性的评估提供了依据。     

基于共轭斜量法的凿岩参数自寻优控制研究

在凿岩过程中,影响凿岩速度的因素主要有凿岩机输出的冲击能、活塞冲击频率、液压推进力、钎杆回转速度和岩石性质。针对目前无法根据岩石性质快速实现凿岩参数的最优匹配,凿岩速度难以达到理论设计最佳值的问题,提出基于共轭斜量法的凿岩参数自寻优控制方案。将冲击能和冲击频率、推进力和转钎速度分成2组进行动态寻优,并充分考虑岩石性质对凿岩速度的影响,使得各凿岩参数可以快速地达到最优匹配关系。利用MATLAB软件对该自寻优方案在采用固定步长和模糊变步长时的应用效果进行仿真分析,验证该方案的可行性和合理性,并进行推进力和转钎速度的自寻优试验,以验证理论分析和仿真结果的正确性。仿真和试验结果表明基于共轭斜量法的自寻优控制方案可使凿岩参数快速收敛于最优值附近,极大地缩短了实现最佳凿岩速度所需的寻优时间,与常规方法相比凿岩速度可提高13.2%。研究结果对岩石开采设备的自寻优控制以及岩石开采效率的提升有良好的指导价值,同时为凿岩自动化和智能化的实现提供了一种新思路。     

非稳态导热理论在矿井原岩温度测定中的应用

矿井的原始地温是矿井热害治理的基础数据,是进行矿井热源分析、井下风温预测以及制定矿井降温措施的重要依据.井巷围岩温度场是非稳态温度场,为测得生产矿井的原始地温往往需要打30~40 m的深孔,其测定时间长、成本高、难度大.根据非稳态导热理论,在采掘工作面打一定深度的浅钻孔,通过测算原岩温度随着时间的变化情况,可以获得该地点的原始地温,并对浅钻孔测温方法的适用条件进行了探讨,并对浅孔的测温过程以及在实际测温中应注意的问题进行了分析.     

节理裂隙围岩小直径深竖井爆破开挖

节理裂隙发育围岩地区小直径、深竖井的爆破开挖,很容易造成塌方和超挖,所以其设计与施工一直是关注重点。结合长沙市森林防火监测站项目80 m深的小直径竖井工程,针对小断面、深竖井的工程特点以及表层围岩石风化严重的地质条件,采取小断面反井爆破、分次扩挖,及地表层正向爆破等施工技术,对保证竖井开挖质量及安全措施进行了详细的分析。结果表明工程设计与施工工艺切实可行。     

Citation-related reliability analysis for a pilot sample of underground coal mines

The scrutiny of underground coal mine safety was heightened because of the disasters that occurred in 2006–2007, and more recently in 2010. In the aftermath of the 2006 incidents, the U.S. Congress passed the Mine Improvement and New Emergency Response Act of 2006 (MINER Act), which strengthened the existing regulations and mandated new laws to address various issues related to emergency preparedness and response, escape from an emergency situation, and protection of miners. The National Mining Association-sponsored Mine Safety Technology and Training Commission study highlighted the role of risk management in identifying and controlling major hazards, which are elements that could come together and cause a mine disaster. In 2007 MSHA revised its approach to the “Pattern of Violations” (POV) process in order to target unsafe mines and then force them to remediate conditions in their mines. The POV approach has certain limitations that make it difficult for it to be enforced. One very understandable way to focus on removing threats from major-hazard conditions is to use citation-related reliability analysis. The citation reliability approach, which focuses on the probability of not getting a citation on a given inspector day, is considered an analogue to the maintenance reliability approach, which many mine operators understand and use. In this study, the citation reliability approach was applied to a stratified random sample of 31 underground coal mines to examine its potential for broader application. The results clearly show the best-performing and worst-performing mines for compliance with mine safety standards, and they highlight differences among different mine sizes.     

白云鄂博铁矿台阶爆破“后排孔”穿爆技术实践

针对白云鄂博铁矿采场台阶爆破区后排断面出现凹槽形和断面预裂的问题,依据利文斯顿爆破漏斗理论,调整后排孔的穿爆技术参数,将后排孔的孔距从9m降到7m,单孔装药量从450kg降到400kg。改进后的后排孔穿爆技术,明显提高爆破质量,爆区后排孔采掘断面规整;后排孔对爆区后方岩体破坏作用降低,振动裂隙减少;爆区后排孔采掘断面预裂缝隙及大块率降低;爆堆后部大块率从20个/万t降低到16个/万t,年节省二次爆破费用约60万元。后排孔穿爆技术改进方案,在保证矿山生产有序高效进行的同时提高了矿山的整体效益,可为其他矿山提供参考。     

Progress of Air Pollution Control in China and Its Challenges and Opportunities in the Ecological Civilization Era

China’s past economic growth has substantially relied on fossil fuels, causing serious air pollution issues. Decoupling economic growth and pollution has become the focus in developing ecological civilization in China. We have analyzed the three-decade progress of air pollution controls in China, highlighting a strategic transformation from emission control toward air quality management. Emission control of sulfur dioxide (SO₂) resolved the deteriorating acid rain issue in China in 2007. Since 2013, control actions on multiple precursors and sectors have targeted the reduction of the concentration of fine particulate matter (PM_2.5), marking a transition to an air-quality-oriented strategy. Increasing ozone (O₃) pollution further requires O₃ and PM_2.5 integrated control strategies with an emphasis on their complex photochemical interactions. Fundamental improvement of air quality in China, as a key indicator for the success of ecological civilization construction, demands the deep de-carbonization of China’s energy system as well as more synergistic pathways to address air pollution and global climate change simultaneously.     

Application of Deep Hole Drilling to the Measurement and Analysis of Residual Stresses in Steel Shrink‐Fitted Assemblies

Abstract: Residual stress measurement of shrink‐fitted assemblies was achieved through finite element simulations and experiments using the deep hole drilling technique. Shrink‐fitted assemblies using stainless steel and cast iron were manufactured and residual stresses measured using a combination of deep hole and centre hole drilling. The results from the finite element simulations demonstrated that modifications to the deep hole drilling method were required to account for plastic relaxation during the measurement process. This was verified through the experimental measurements. The results from both the stainless steel and cast iron assemblies provided a clear demonstration that the final residual stress state was a consequence of the machining and assembly of the components.     

黑岱沟露天矿岩体可爆性及爆破对炸药性能要求的研究

根据黑岱沟露天矿煤层覆盖条件,对现场不同岩体进行波速测试,得到泥岩岩体、砂岩岩体和泥岩、砂岩、黏土交错岩体的波速;在实验室对泥岩、砂岩进行岩石波速测试和岩石强度试验,得到泥岩和砂岩的波速和抗压强度。对岩体的可爆性进行了研究,并对炸药、岩石、岩体的波阻抗进行分析研究,当炸药波阻抗与岩体波阻抗匹配时,在同样炸药量取得相同爆破效果情况下,孔网参数可以大幅增加,节约了钻孔费用和减轻钻机钻孔压力。     

大孔径浅台阶控制爆破在重庆地区的应用

重庆地区山多坡缓、临近建（构）筑物多,为了在邻近城市主城区、城镇聚集区安全高效的进行土石方开挖作业,结合重庆地区的地形、地质条件,经过理论分析和现场试验,提出了一种钻孔直径80~90mm、钻孔深度3m、孔网参数为3mX2.5m、以挖机钻为核心施工机具的大孔径浅台阶控制爆破的施工方案。该方法在重庆地区得到了良好的推广和应用,取得了良好的经济效益和社会效益,可广泛应用于各种城镇石方控制爆破、基坑及深基坑开挖和大型土石方开挖等。     

Miners' exposure to radon and its decay products in some Iranian non-uranium underground mines

Measurements of radon, radon decay products and gamma exposure rate in 12 non-uranium underground mines have been carried out in order to estimate the occupational radiation exposure of miners. Continuous measurements of radon using pulse ionisation chambers and scintillation cell techniques were employed for these studies. Progenies of radon were collected on filter paper, and then a three-count procedure was used for the measurement. The equilibrium state between radon and its decay products has been determined. Concentrations of natural radionuclides ((226)Ra, (232)Th and (40)K) in ore and soil samples taken from various locations in each mine have been measured using a Canberra High Purity Germanium detector. Based on these measurements two ranges of dose were evident. Doses ranged from 0.1 to 1.52 mSv y(-1) for nine mines and from 10 to 31 mSv y(-1) for the other three mines. A separate grouping of the mines was recognised from radon concentrations, which varied from 2 Bq m(-3) to 10 kBq m(-3). In three of these mines, working level (WL) concentrations of the order of 36-1771 mWL were determined in different working areas. In all other mines, the concentrations were observed to be <45 mWL.     

In vivo measurements of 210Pb in skull and knee geometries as an indicator of cumulative 222Rn exposure in a underground coal mine in Brazil

Cumulative exposure to radon can be evaluated by measuring (210)Pb in bone. The skull and knee are two convenient parts of the skeleton for in vivo measuring (210)Pb because these regions of the body present a high concentration of bone, the detectors are easily positioned and the likelihood of cross contribution from other organs or tissues is low. A radiological survey of non-uranium mines in Brazil indicated that an underground coal mine in Paraná, located in the south of Brazil, exhibited a high radon concentration. In vivo measurements of 32 underground coal miners were performed in the IRD-CNEN Whole Body Counter shielded room using an array of four high-resolution germanium detectors. Estimations of (210)Pb in the total skeleton were determined from direct in vivo measurements of (210)Pb in the head and knees. In vivo measurements of (210)Pb in 6 out of 32 underground coal miners ranged from 80 to 164 Bq, suggesting that these workers were significantly exposed to (222)Rn.     

NORM workers: a challenge for internal dosimetry programmes

The mining, milling and processing of uranium and thorium bearing minerals may result in radiation doses to workers. The control of occupational exposures from these natural sources of radiation imposes a challenge to regulators and radiation protection advisers. A survey pilot programme, which included six mines in Brazil and a monazite plant, was established, consisting of the collection and analysis of concentrations of uranium, thorium and polonium in urine, faeces and air samples. Results from workers were compared to background data from their families living in the same area and from residents from the population of Rio de Janeiro. Positive exposure results were identified among the coal miners, the niobium miners and the monazite sand workers. Difficulties in the application of internal dosimetry programmes are discussed in relation to the control of NORM workers.