Prediction of risk factors of cyberbullying-related words in Korea: Application of data mining using social big data

The study examined a decision tree analysis using social big data to conduct the prediction model on types of risk factors related to cyberbullying in Korea. The study conducted an analysis of 103,212 buzzes that had noted causes of cyberbullying and data were collected from 227 online channels, such as news websites, blogs, online groups, social network services, and online bulletin boards. Using opinion-mining method and decision tree analysis, the types of cyberbullying were sorted using SPSS 25.0. The results indicated that the total rate of types of cyberbullying in Korea was 44%, which consisted of 32.3% victims, 6.4% perpetrators, and 5.3% bystanders. According to the results, the impulse factor was also the greatest influence on the prediction of the risk factors and the propensity for dominance factor was the second greatest factor predicting the types of risk factors. In particular, the impulse factor had the most significant effect on bystanders, and the propensity for dominance factor was also significant in influencing online perpetrators. It is necessary to develop a program to diminish the impulses that were initiated by bystanders as well as victims and perpetrators because many of those bystanders have tended to aggravate impulsive cyberbullying behaviors.     

Hydrogen wettability of clays: Implications for underground hydrogen storage

This study investigates the ability of hydrogen (H₂) to wet clay surfaces in the presence of brine, with implications for underground hydrogen storage in clay-containing reservoirs. Rather than measuring contact angles directly with hydrogen gas, a suite of other gases (carbon dioxide (CO₂), argon (Ar), nitrogen (N₂), and helium (He)) were employed in the gas-brine-clay system under storage conditions (moderate temperature (333 K) and high pressures (5, 10, 15, and 20 MPa)), characteristic of a subsurface environment with a shallow geothermal gradient. By virtue of analogies to H₂ and empirical correlations, wettabilities of hydrogen on three clay surfaces were mathematically derived and interpreted. The three clays were kaolinite, illite, and montmorillonite and represent 1:1, 2:1 non-expansive, and 2:1 expansive clay groups, respectively. All clays showed water-wetting behaviour with contact angles below 40° under all experimental set-ups. It follows that the presence of clays in the reservoir (or caprock) is conducive to capillary and/or residual trapping of the gas. Another positive inference is that any tested gas, particularly nitrogen, is suitable as cushion gas to maintain formation pressure during hydrogen storage because they all turned out to be more gas-wetting than hydrogen on the clay surfaces; this allows easier displacement and/or retrieval of hydrogen during injection/production. One downside of the predominant water wettability of the clays is the upstaged role of biogeochemical reactions at the wetted brine-clay/silicate interface and their potential to affect porosity and permeability. Water-wetting decreased from kaolinite as most water-wetting clay over illite to montmorillonite as most hydrogen-wetting clay. Their wetting behaviour is consistent with molecular dynamic modelling that establishes that the accessible basal plane of kaolinite's octahedral sheet is highly hydrophilic and enables strong hydrogen bonds whereas the same octahedral sheet in illite and montmorillonite is not accessible to the brine, rendering these clays less water-wetting.     

An Innovative Non-Pillar Coal-Mining Technology with Automatically Formed Entry: A Case Study

A non-pillar coal-mining technology with an automatically formed entry is proposed, which reduces the waste of coal resources and the underground entry drivage workload. Three key techniques in this technology cooperate to achieve automatic formation and retaining of the gob-side entry, and to realize non-pillar mining. Constant-resistance large deformation (CRLD) support ensures the stability of the entry roof; directional presplitting blasting (DPB) separates the entry roof and the gob roof; and a blocking-gangue support system (BGSS) integrates the caved rock material as an effective entry rib. An industrial test was conducted to verify the engineering effects of these key techniques. The field application results showed that the retained entry was under the pressure-relief zone due to the broken-expansion nature of the caved rock mass within the DPB height. After going through a provisional dynamic pressure-bearing zone, the retained entry entered the stability zone. The final stable entry meets the requirements of safety and production. The research results demonstrate the good engineering applicability of this technology. By taking the framework of the technology design principles into consideration and adjusting the measures according to different site conditions, it is expected that the proposed non-pillar coal-mining technology can be popularized on a large scale.     

煤矿智能化开采关键技术分析

煤矿智能化开采是中国煤炭工业技术发展的必经之路,是煤矿企业进一步发展的主要目标。通过阐述智能化的概念,介绍了煤矿智能化开采的定义和系统构成,分析了煤矿智能化开采的关键技术,包括工作面综采装备位姿监测技术、围岩-装备耦合自适应控制技术、综采装备核心智能控制技术和矿井机器人技术。针对各关键技术问题进行分析,提出相应的解决方案和核心装备智能化控制逻辑。通过解决煤矿智能化开采过程中的关键技术问题,加快煤矿企业智能化改革,确保企业稳定、可持续发展。     

SAM智能综采技术在龙滩煤矿的应用

介绍了四川省首个智能综采设备在龙滩煤矿3124S工作面的应用情况,总结了SAM智能化综采的六大核心技术,包括成套设备一键启停、液压支架自动跟机、采煤机记忆割煤、机巷远程集中控制、工作环境智能监控、工况监测及故障诊断。通过现场应用,一键启停功能成功率超过90%、自动跟机率平均88%、记忆割煤使用率62%,实现了工作面设备集中控制、回采参数实时监控及故障诊断。结果表明,相较于传统综采工作面,智能化综采工作面生产人员减少50%,工效提高63%,单产提高65%。     

辛置煤矿10#煤综采工作面防灭火技术研究与应用

针对辛置煤矿10#煤综采工作面煤层自然发火的特点,采用现场实测分析及注胶防灭火的方法,对工作面煤体漏风情况、回采巷道内风流温度、CO及CH4浓度进行了监测,并应用了注胶防灭火的技术。针对工作面煤体内多处漏风严重,应用粉煤灰、高分子胶体注胶技术进行防治后,各监测点风流温度及煤层温度均得到有效降低,保证了工作面安全推进。     

综采工作面沿空留巷支护技术应用

为了提高无煤柱回采工作面沿空留巷顶板稳定性,保证工作面安全高效回采,对8304无煤柱工作面沿空留巷段采取爆破切顶施工工艺,以及“恒阻锚索+支设T型钢棚+迈步式W型锚索吊棚”联合支护措施,控制了沿空留巷围岩稳定性,保证了安全生产。     

宏阳煤矿薄煤层沿空留巷实践应用

为了缓解矿井采掘接替紧张局面,宏阳煤矿采用沿空留巷技术,对12102运输顺槽采取顶板超前采面打设锚索梁、顶板超前预裂爆破,留巷段采用“钢梁+单体液压支柱”的方式进行巷道支护。该技术现场应用后,减少了巷道掘进工程量,减少了煤炭损失,增加了经济效益,降低了职工劳动强度,有利于采掘接替。     

深部大采高工作面煤柱留设优化数值模拟研究

为缓解高产高效矿井采掘接续紧张局面，鄂尔多斯地区综采工作面多采用“两进一回”的巷道布置形式，辅运巷在回采结束后用作下一工作面的回风巷，两进风巷之间采用大煤柱护巷。但随着该地区采深600 m以上的深部矿井增多，冲击地压灾害问题逐渐显现，双巷大煤柱留设的弊端也暴露出来。针对此问题，以鄂尔多斯红庆河煤矿3^-1101大采高综采工作面为例，对不同宽度煤柱留设的应力分布规律进行建模研究，提出了合理的煤柱留设宽度，为鄂尔多斯地区类似条件矿井的安全高效开采提供参考依据。