Study of the features of outburst caused by rock cross-cut coal uncovering and the law of gas dilatation energy release

To study the law of gas dilatation energy release of rock cross-cut coal uncovering face, according to the analysis of the physical parameters distribution features of coal and rock mass in front of crosscut face,the equations of elastic potential of coal and gas dilatation energy theory were set up to process a contrast calculation of the sizes of two kinds of energy. The results show that gas dilatation energy is the uppermost energy source causing outburst occurrence. Furthermore, the mathematical model of spherical flow field gas dilatation energy release was established and MATLAB software was applied to make a numerical calculation analysis on the law of gas dilatation energy release. The results indicate that the gas dilatation energy is closely related to gas parameters and its energy index does reflect the possibility of coal seam outburst.

Quick determination of gas pressure before uncovering coal in cross-cuts and shafts

The determination of gas pressure before uncovering coal in cross-cuts and in shafts is one of the important steps in pre- dicting coal and gas outbursts. However, the time spent for testing gas pressure is, at present, very long, seriously affecting the ap- plication of outburst prediction techniques in opening coal seams in cross-cuts and shafts. In order to reduce the time needed in gas pressure tests and to improve the accuracy of tests, we analyzed the process of gas pressure tests and examined the effect of the length of boreholes in coal seams in tests. The result shows that 1) the shorter the borehole, the easier the real pressure value of gas can be obtained and 2) the main factors affecting the time spent in gas pressure tests are the length of the borehole in coal seams, the gas emission time after the borehole has been formed and the quality of the borehole-sealing. The longer the length of the bore- hole, the longer the gas emission time and the larger the pressure-relief circle formed around the borehole, the longer the time needed for pressure tests. By controlling the length of the borehole in a test case in the Huainan mining area, and adopting a quick sealing technique using a sticky liquid method, the sealing quality was clearly improved and the gas emission time as well as the amount of gas discharged greatly decreased. Before the method described, the time required for the gas pressure to increase during the pressure test process, was more than 10 days. With our new method the required time is only 5 hours. In addition, the accuracy of the gas pressure test is greatly improved.

Evolution characteristics of precursor information of coal and gas outburst in deep rock cross‑cut coal uncovering

As mines become deeper,the potential for coal and gas outbursts in deep rock cross-cut coal uncovering is enhanced.The outburst precursors are unclear,which restricts the effectiveness and reliability of warning systems.To reveal the evolution characteristics of coal and gas outburst precursor information in deep rock cross-cut coal uncovering,briquette specimens are constructed and experiments are conducted using a self-developed true triaxial outburst test system.Using acoustic emission monitoring technology,the dynamic failure of coal is monitored,and variations in the root mean square(RMS)of the acoustic emissions allow the effective cracking time and effective cracking gas pressure to be defined.These characteristics are obviously different in deep and shallow coal.The characteristic parameters of gas outburst exhibit stepwise variations at different depths.The RMS and cumulative RMS have stepped failure characteristics with respect to changes in gas pressure.The characteristic parameters of coal failure are negatively correlated with the average in-situ stress and effective stress,but positively correlated with the lateral pressure coefficient of in-situ stress and the critical gas pressure.The transition characteristics are highly sensitive in all cases.The critical depth between deep and shallow coal and gas outbursts is 1700 m.The expansion multiple of acoustic emission intensity from the microfracture stage to the sharp-fracture stage of coal is defined as the outburst risk index,N1.For depths of 1100–1700 m,N1≥7 denotes a higher risk of outburst,whereas at depths of 1700–2500 m,N1≥3 indicates enhanced risk.

在internet网上使用免费的UnCover数据库

本文介绍了UnCover数据库的情况和如何在此库上免费检索文献。

UnCover 期刊文献检索系统

根据作者个人的网上检索实践，对期刊文献库免费联机检索系统ＵｎＣｏｖ－ｅｒ的概况、服务方式、联机过程及如何检索作介绍。

医学科研应利用UnCover数据库的特色功能

通过对UnCover数据库的收录分析和特色功能介绍,为医学和其它科研人员提供依据和信息。

A race to uncover a panoramic view of primary liver cancer

Introduction Primary liver cancer, the second most common cause of cancer related death worldwide, presents ethnic, etiological, sex, and geographical diversity2 （Figure 1A）. At the histological level, liver cancer includes two major types： hepatocellular carcinoma （HCC, about 80%） and cholangiocarcinoma （CCA, about 15%）. Many etiological factors contribute to HCC development, such as hepatitis B virus （HBV）, hepatitis C virus （HCV）, aflatoxin B1 （AFB1）, alcohol, and metabolic diseases3. By contrast, the major risk factors for CCA are liver flukes （Opisthorchis viverrini and Clonorchis sinensis） and primary sclerosing cholangitis4,

Optimization Algorithms for Fully Automatic Optimizing Cross-cut Saw

The optimization of boards by grades plays an important role in the production for cross cutting boards, and the outturn rate and utilization of boards are directly affected by the optimization results of boards by grades. At present, the OptiCut series fully automatic optimizing cross-cut saw（FAOCCS） from Germany Weinig Group occupies the main markets in the world, but no report about the relative theories on the optimization technology and its algorithms is available. There exist some disadvantages in woodworking machinery and equipment used for cross cutting boards in China, for example, low sawing precision, outturn rate of boards and productivity, and difficulty in making statistics on the sawing results. Three optimization modes are presented for the optimization algorithms for FAOCCS, namely, optimization of fixed length, optimization of finger-jointed lumber and mixed optimization. Mathematical models are then established for these three optimization modes, and the corresponding software for realizing the optimization is prepared. Finally, Synthetic evaluation on the established mathematical models is presented through three practical examples. The results of synthetic evaluation indicate that FAOCCS using the optimization modes may raise the outturn rate of boards approximately 8% and the productivity obviously, and allows accurate statistics on the cross cut products of boards. The mathematical models of above three optimization modes are useful for increasing the outturn rate and utilization ratio of boards.

Implement Constitutional Principles to Uncover Tort Cases——An interview with Wang Zhenchuan, deputy chief procurator of the Supreme People's Procuratorate

EDITOR'S NOTE: Since May 2004, the people's procuratorates in China have concentrated their efforts on uncovering cases of encroaching upon human rights by government functionaries by abusing their power. The move has aroused extensive attention. On this, our staff reporter interviewed Deputy Chief Procurator Wang Zhenchuan, who is in charge of the campaign against human rights violations.

不同揭膜方式对植烟土壤养分分布规律和烟叶质量的影响

[目的]为优质烟生产的合理追肥提供依据。[方法]采集各处理不同深度土壤样品,分析速效氮、磷、钾养分含量,研究农艺措施对不同土层养分的影响。[结果]烟株生育过程中,烟株主要根区0~30 cm土层不同处理速效氮、0~20 cm土层速效磷在烟株生育期内总体呈先升后降的“凸”型变化;0~10 cm土层氮素峰值出现在移栽后30 d,磷素峰值出现在移栽后60 d;10~30 cm土层氮素峰值出现在移栽时,采烤结束时,常规揭膜培土处理0~10 cm土层速效氮低于本底值,其余处理0~10 cm土层速效氮高于本底值,10~20 cm土层速效磷峰值出现在移栽后30 d,20~30 cm土层速效磷呈非线性增加的“S”型变化。除对照处理外,其余处理0~10 cm速效钾呈“S”型非线性增加趋势,10~20 cm土层速效钾含量均呈“凸”型变化,峰值出现在移栽时,除C处理外,其余处理20~30 cm速效钾呈“S”型非线性增加趋势,E处理积累钾素最多。[结论]烟株周围破膜(直径20 cm)正常培土处理0~30 cm土层养分移动与烟株生长需肥规律吻合,有利于平衡烟叶化学成分,提高烤烟产质量和经济效益。

石门揭煤局部防突措施研究进展及展望

随着矿井开采深度的增加,瓦斯突出问题日益凸显,如何快速安全地进行石门揭煤,是保障煤矿安全生产的重要目标。选取中国知网数据库中近30年相关文献为样本,基于图谱分析法,分析了石门揭煤局部防突领域中的研究热点;对防突措施的研究进展和不足之处进行了系统探析,分析发现低温冷冻技术从降低煤层储能及提高煤体强度2个角度实现防突。煤与瓦斯突出事故的发生是煤层储能失稳后突破了煤体抵抗能力导致的,基于目前局部防突领域存在的技术难题以及人工冻结存在的不足,结合智能化技术,提出智能“钻-抽-注”一体化措施,通过信号基站及局域网络进行实时监控及预警,实现精准防突;通过建立多物理场耦合模型、理论分析及工程实践验证3方面相结合,掌握冷冻条件下煤岩体瓦斯赋存状态及运移规律,为低温冷冻技术在石门揭煤局部防突中的应用提供理论依据;借助智能液氮冻结系统,实现“一孔多功能”,为石门揭煤局部防突工作提供新的选择和支持,从而快速、安全揭开突出危险性煤层。

三种手术方式治疗鼻前庭囊肿的临床观察

目的:探讨唇龈沟径路鼻前庭囊肿切除术、鼻内镜下鼻前庭囊肿揭盖术、鼻内镜下鼻前庭囊肿切除术三种手术方式治疗鼻前庭囊肿(NVC)的临床疗效。方法:回顾性分析南京医科大学附属南京医院耳鼻咽喉科2013年1月~2020年6月手术治疗的64例NVC患者,分为A、B、C组,A组为唇龈沟径路鼻前庭囊肿切除术23例,B组为鼻内镜下鼻前庭囊肿揭盖术22例,C组为鼻内镜下鼻前庭囊肿切除术19例。分析三组术中及术后的康复情况,评估手术治疗的效果。结果:B、C两组在手术时长、术中出血量、切口愈合时间、术后在院时间、术后面部肿胀等情况均优于A组,差异具有统计学意义(P<0.05)。B、C两组术后第1天、第2天、第3天、第5天疼痛视觉模拟评分(VAS)均低于A组;B、C两组比较,B组创口愈合时间短于C组,差异有统计学意义(P<0.05)。结论:与唇龈沟进路鼻前庭囊肿切除术相比,鼻内镜下鼻前庭囊肿揭盖术、鼻内镜下鼻前庭囊肿切除术治疗NVC具有手术时间短、出血少、切口愈合快、术后并发症少等优势。鼻内镜下揭盖术伤口愈合时间优于鼻内镜下切除术,因此,鼻内镜下鼻前庭囊肿揭盖术适合在临床上广泛推广,鼻内镜下切除术可作为传统的唇龈沟进路切除术、鼻内镜下揭盖术复发病例的补充治疗。

“蔽”无可避:荀子“解蔽”的诠释学考察

“解蔽”是荀子提出的思想主张,集中体现在《荀子·解蔽》篇中。“解蔽”指解除理解中的不合理前见。荀子把人性中的情与知的偏见都视为“蔽”,以礼让忠信和君王统治的实践效果作为评判“蔽”的依据,主张以“化性起伪”涤除人性之蔽,用“虚一而静”解除知识之蔽。荀子的“解蔽”仍有其蔽,他的“解蔽”是以孔子仁义之道这一前见取代其他诸子前见,目的是把儒家思想建成具有唯一合理性的前见。荀子因其“蔽”而成就自身的同时,却局限于自我的理解之蔽,否定了诸子思想之“蔽”的积极意义,阻碍了思想的平等对话与会通,所以,荀子的“解蔽”是一种独断型的诠释模式。

分段卷放保温被对日光温室光热效应的影响

为减少温室热量损失,以阿克苏地区日光温室为研究对象,根据新疆实际情况,设计分段式日光温室保温被揭盖方式,通过连续观测温室内光照强度与空气温度变化,证实分段式保温被揭盖比一次性全揭开方式使温室前、后部气温平均值分别提高0.6℃和0.8℃,白天可使温室气温增温速率更快,降温速率更慢。在阴天可以增高温室内后部的光照强度;因此分段卷放保温被可以有效提升新疆日光温室性能,增强温室保温蓄热能力。

解蔽与遮蔽:热点事件中“梗”现象的省思

互联网中伴随热点事件广为流传的“梗”具有解蔽与遮蔽两方面的作用。一方面,“梗”解蔽着人们对热点事件的感性认知,从“人寓于梗”的具象化存在,到“人追寻梗”的趣缘结构,最终形成“人输出梗”的感性意识形态,充分彰显了公众对于热点事件的感性认知与价值认同;另一方面,过度抢占公众视野的“梗”使人们陷入人云亦云式的共在关系与巴赫金式的狂欢中,遮蔽了公众对热点事件的理性之思,引发理智缺失、盲目跟从的舆论乱象。克服热点事件中“梗”的遮蔽问题,需要发挥“梗”的“技术调节”作用,形塑人们对热点事件的正确认知,这也为新媒体时代处置热点事件舆情提供了新的视域。

防风穿孔铝单板金属屋面系统施工关键技术

以珠海机场综合交通枢纽项目一期工程为依托,针对工程金属屋面对材料强度、性能及外观的要求,采用一种防风穿孔铝单板金属屋面系统。从金属屋面系统优势、结构组成及施工关键技术等方面入手,阐述防风穿孔铝单板金属屋面系统从结构设计到现场施工的整体流程,对抗风揭防渗漏敏感部位进行专项研究,从而推动金属屋面施工技术发展。

桐梓隧道多煤层地质煤与瓦斯突出风险性分析

为探明桐梓隧道穿越煤层煤与瓦斯突出风险性,布置参数井查明隧道所在区域地层、构造、煤层以及煤层气储层特征。分析结果表明:钻遇煤层7层,煤层厚度大于0.3m有4层,煤类为贫煤,C3、C6煤层为有煤尘爆炸性,煤层隧道附近瓦斯含量3.10~11.29m^(3)/t,C3、C5、C6、C7煤层瓦斯压力均大于1.0MPa,瓦斯放散初速度均大于10mmHg,C3、C5、C6、C7煤层具有煤与瓦斯突出危险性。钻探分析结果为该地区类似工程提供参考和借鉴。

下行穿层钻孔消突技术在揭煤中的应用实践

阳泉煤业集团泊里煤矿有限公司主提升井为副立井,井深640 m,主要用于生产期间提料及人员上下井。为保证后期井底淤泥、积水得到有效排除,需在副立井井底施工一条检修巷道,即井底水窝清理斜巷。施工过程中,巷道底板赋存有15#煤层,煤层平均厚度5.3 m,且具有突出危险性。通过在揭露煤层前采取下行穿层钻孔并造穴,预抽煤层瓦斯后经效果检验瓦斯含量、瓦斯压力均小于临界值,有效的对突出煤层进行了消突,保证了巷道顺利施工。

石门揭煤作业中定向长钻孔瓦斯抽采防突技术的应用

研究专注于煤矿工作面瓦斯防突技术的应用,特别是定向长钻孔瓦斯抽采防突技术在石门揭煤作业中应用。旨在评估这一技术在防止瓦斯突出方面的有效性,以确保煤矿安全和生产符合相关法规。为确保工作面的安全推进,在工作面前方的煤层区域设置检验钻孔,用于测定残余瓦斯压力和含量,并确保其符合标准。研究结果显示,实际操作中的残余瓦斯含量和压力均满足相关标准,5个检测钻孔的瓦斯压力平均值为0.522 MPa,瓦斯含量为4.5 m3/t,满足瓦斯含量小于8 m3/t、瓦斯压力小于0.74 MPa的要求。表明该技术可以有效防止瓦斯突出。另外,采用钻屑瓦斯解吸指标法进行突出危险性评估,结果显示在揭煤阶段的工作面不再有突出危险,可以继续进行揭煤工作。