Numerical and theoretical investigations of the effect of the gangue-coal density ratio on the drawing mechanism in longwall top-coal caving

Discrete element calculations of the top-coal drawing process for diferent gangue-coal density ratios were conducted to investigate the efect of the gangue-coal density ratio on the drawing mechanism in longwall top-coal caving.The efects were analyzed for the drawing body,the top-coal boundary,and the recovery of top coal.The results show that for increasing density ratio,the initial drawing body on the goaf side is farther away from the drawing support and its width and volume gradually increase.The upper part of the sickle-shaped drawing body extends near the initial drawing body with increasing density ratio in the normal cycling stage,and the distance from the drawing body to the initial drawing body is its maximum width.The larger the density ratio,the smaller the height of the top coal above the goaf at the end of the initial drawing process.The height of the top-coal boundary decreases with increasing density ratio,until it reaches a limit.In a normal cycle,due to hysteretic development,the top-coal boundary moves toward the goaf until the density ratio is approximately 2.0,which is consistent with the physical experiment results.Finally,increasing the advance length of the working face is benefcial for increasing the overall recovery of top coal.

Surface mining subsidence control based on grouting-recovery ratio theory

From an analysis of the relationships of grouting coefficients under the conditions of grouting reducing subsidence, it is concluded that the reducing subsidence rate is in direct proportion to the grouting-recovery ratio, and its proportional coefficient depends on the coefficient of reducing subsidence and collapsing coefficient.The coefficient for reducing subsidence volume φ=ΔV/V_(ash) is related to overburden lithology.The coefficient for reducing subsidence volume φ is always larger than 1.This improves the reducing subsidence rate,the grouting-recovery ratio, and the coefficient for reducing subsidence volume, which can maximize the control of surface subsidence.

Numerical Simulation of High Concentration Polymer Flooding in Oilfield Development

The field test of high concentration polymer flooding has the characteristics of high cost, long cycle and irreversibility of the reservoir development process. In order to ensure the best development effect of the development block, this paper simulated and calculated the high concentration polymer flooding development case of the polymer flooding pilot test area through numerical simulation research, and selected the best case through the comparison of various development indicators. The simulation results showed that the larger the polymer dosage and the higher the concentration, the better the oil displacement effect. The best injection method in the construction process was the overall injection of high concentration polymer. The test area should implement high concentration polymer oil displacement as soon as possible. The research results provided theoretical guidance for the future development and management of the pilot area.

内耳三维真实重建反转恢复成像与突发性聋预后

目的分析突发性聋(突聋)患者的内耳三维真实重建反转恢复(three dimensional real inversion recovery,3D Real IR)成像表现,探讨内耳不同信号强度与突聋预后的关系。方法选取2022年9月25日—2023年4月10日郑州大学第五附属医院耳鼻咽喉科住院治疗及门诊治疗的单侧突聋患者60例,按照听力曲线将患者分为低频下降型4例、高频下降型1例、平坦下降型34例和全聋型21例。由于平坦下降型和全聋型治疗方法一致,将平坦下降型和全聋型的55例患者按治疗有效与否分为无效组25例和有效组30例;按治疗前听力分级,分为轻度听力损失组11例、中度听力损失组7例、重度听力损失组16例和极重度听力损失组21例;根据听力下降与否分为患耳组55耳和健耳组55耳。比较患耳和健耳的耳蜗信号强度,并测量延髓信号强度,分别计算耳蜗/延髓(cochlea/medulla ratio,CM)比值,分析耳蜗信号强度与治疗结果之间关系。结果无效组CM比值明显高于治疗有效组,差异有统计学意义(P<0.001);患耳组与健耳组CM比值比较,差异有统计学意义(P<0.05)。轻度、中度、重度和极重度听力损失组患耳CM比值比较(2.57±3.02 vs 1.77±0.87 vs 2.04±1.98 vs 2.51±2.33),差异无统计学意义(F=0.304,P=0.823)。结论内耳3D Real IR可显示突聋患者血-迷路屏障通透性的改变,CM比值可以更精确了解突聋患者内耳受损的程度,CM比值大小与听力损失程度并不一致,可以单独作为一种判断突聋预后的因素。突聋患者CM比值高于1.58提示可能预后不良。

血-迷路屏障通透性与突聋发病机制及预后的关系:在3D real IR的发现

目的分析突聋患者的内耳钆造影MRI三维真实重建反转恢复(three dimensional real inversion recovery,3D real IR)成像上的表现,探讨血-迷路屏障的通透性与突聋发病机制及其预后的关系。方法对41例单侧突聋患者行内耳钆造影MRI,测量患耳和健耳的耳蜗信号强度,并测量延髓信号强度,分别计算出耳蜗/延髓比值(cochlear/medulla ratio,CM ratio),以CM比值作为血-迷路屏障通透性的标志物,分析突聋患者患耳、健耳CM比值的不对称程度与疗效之间的关系。结果41例患者中,33例(80.48%)患耳的CM比值高于健耳,差异有统计学意义(P<0.05);患耳CM比值为健耳的1.5倍以下者18例,治疗有效率为77.78%(14/18);患侧CM比值不高于健侧者8例,治疗有效率为100%;达到健耳的1.5倍至1.75倍之间者7例,治疗有效率为100%(7/7);达到健耳的1.75倍至2.0倍之间者2例,治疗有效率为50%(1/2);达到健耳的2.0倍以上者14例,治疗有效率为14.28%(12/14);差异有统计学意义(P<0.05)。结论内耳3D Real IR可显示突聋患者血-迷路屏障通透性的改变,80.48%的突聋患者患侧耳蜗出现高信号,患耳CM比值达健耳的1.75倍以上者多数预后不良。

不同驱替阶段砾岩油藏内油采出规律

聚合物/表表面活性剂二元复合驱是在水驱后提高不同模态砾岩油藏采收率的重要技术,但应用二元复合驱时,对不同砾岩油藏却产生了不同的驱油效果,而对于该方面的研究当前还比较少。基于室内岩心驱油实验结合核磁共振在线监测和CT扫描,对单、双和复模态砾岩油藏在不同开采阶段的剩余油分布和不同孔隙内油的采出规律进行研究。结果表明,水驱阶段,复模态岩心的采收率最高,其次是单模态岩心,双模态岩心的采收率最低,3种模态岩心采收率分别为31.4%、25.8%、33.4%。而二元复合驱阶段岩心提高采收率幅度为:双模态>复模态>单模态,分别提高了27.9、26.4、19百分点,且3种模态岩心在二元复合驱时的孔隙动用下限均降低,且复模态岩心的降低幅度高于双模态岩心和单模态岩心。单、双、复模态岩心的非均质性逐渐增强,单模态岩心水驱阶段均匀驱替,采收率高;复模态岩心中的油主要集中在孔径为32.7~52.5μm的优势大孔中,在水驱阶段油也被大量采出,导致剩余油量低;双模态岩心中大孔内油量较复模态低,水驱采收率低,剩余油量高。在二元复合驱阶段,由于调驱作用和水驱后剩余油量影响,双模态岩心提高采收率效果最好,其次是复模态岩心。

陆相页岩层系岩心中气态烃井场测定技术初步应用及展望

陆相页岩层系的流体分析是页岩油甜点评价的重要基础,针对岩心样品中气态烃易于散失的特性和页岩油钻井现场的需求,研发了井场岩心气态烃快速采集测定装置及方法,探讨了基于岩心气态烃分析和热解含油性分析资料快速计算视气油比和估算游离油损失的方法。研究表明,该装置适用于全直径岩心和块状样品的气态烃检测,既可以实现全直径岩心在常温、常压下逸散气态烃的采集测定,也可以测定块状岩心样品的气态烃总量,气态烃检测相对误差10%,测试结果可以转换为单位质量岩样气态烃含量。全直径岩心逸散气分析可实现岩心气态烃的非破坏式采集和测定,反映了页岩层系垂向上含油气性及其非均质性的变化特征。视气油比可反映页岩层系含油气性和可流动性的趋势,视气油比越大,代表相应页岩层系页岩油可流动性越好。利用视气油比可估算岩心经历降压降温脱气过程中游离烃的损失量,在建立岩心降温降压脱气过程的热解游离烃损失恢复方法中具有较大应用潜力。岩心气态烃井场测定技术丰富了适用于井场的岩心流体分析实验技术手段和方法,为陆相页岩层系流体评价及甜点确定提供数据支撑。

原位二氧化碳泡沫驱提高采收率实验

原位CO_(2)泡沫驱是一种很有潜力的提高采收率技术。通过原位CO_(2)泡沫驱提高采收率实验,优化了生气体系、泡沫体系以及注入参数,得到了最佳的注入量、注入速度和适用的渗透率级差范围。研究结果表明,在温度为70℃,地层水矿化度为10 000 mg/L条件下,得到可以作用于地层深部的原位CO_(2)泡沫体系,其配方为:2.1%碳酸氢铵+1.6%醋酸+9.5%氯化铵+0.1%α-烯烃磺酸钠AOS+0.1%油酸酰胺丙基甜菜碱DHSB,泡沫体积可达810 mL,泡沫综合指数为15552 mL·min。该体系形成的泡沫在油藏中部具有较高黏度和较大弹性的特性,能够有效封堵高渗通道,表现出良好的封堵能力。在渗透率级差为6左右时,原位CO_(2)泡沫体系注入速度控制在1.0mL/min左右,注入段塞量控制在0.3 PV,能够发挥最佳的调驱效果。研究还发现,该泡沫体系在渗透率级差为3.9~13.7的非均质储层中能有效提高采收率,而在渗透率级差为15.6的条件下,虽然未能显著提高低渗层采收率,但在高渗管中仍然有一定的洗油作用。本研究为原位CO_(2)泡沫驱技术的应用和优化提供了重要参考。

Location of Asymmetric Ground Fault Using Virtual Injected Current Ratio and Two-stage Recovery Strategy in Distribution Networks

Sparse measurements challenge fault location in distribution networks.This paper proposes a method for asymmetric ground fault location in distribution networks with limited measurements.A virtual injected current vector is formulated to estimate the fault line,which can be reconstructed from voltage sags measured at a few buses using compressive sensing(CS).The relationship between the virtual injected current ratio(VICR)and fault position is deduced from circuit analysis to pinpoint the fault.Furthermore,a two-stage recovery strategy is proposed for improving reconstruction accuracy of the current vector,where two different sensing matrixes are utilized to improve the incoherence.The proposed method is validated in IEEE 34 node test feeder.Simulation results show asymmetric ground fault type,resistance,fault position and access of distributed generators(DGs)do not significantly influence performance of our method.In addition,it works effectively under various scenarios of noisy measurement and line parameter error.Validations on 134 node test feeders prove the proposed method is also suitable for systems with more complex structure.

基于改进VMD-WTFD算法的二次谐波光谱信号反演分析

采用变分模态分解和小波阈值调整函数(VMD-WTFD)算法在处理噪声时,信号波形恢复往往偏离标准的谐波信号,导致反演结果出现偏差。提出了一种改进VMD-WTFD算法,该算法采用新型阈值函数对VMD-WTFD算法进行改进,然后以此改进算法对二次谐波光谱信号进行反演分析。仿真与实验结果表明:与其它几种降噪算法相比,改进VMD-WTFD算法在不同调制度下反演出的原始信号的峰值、峰位和峰谷值更接近原始标准二次谐波光谱信号,去噪后的信噪比为17.545 dB,相关系数可达到0.9929;可以较清晰地反演出人体呼出气体中CO_(2)的二次谐波幅值。

铝土矿高水材料逐巷充填矿柱回收技术及应用

奥家湾铝土矿采用房柱式采矿法,留设大量矿柱支撑顶板,采出率低,矿石损失量大。为安全回收铝土矿柱,理论分析了充填前后矿柱及充填体的应力分布状态,根据铝土矿体赋存特征及开采条件,提出了高水材料逐巷充填矿柱回收技术并开展了现场试验:将铝土矿柱划分多条采巷,开采完毕后采用水灰比为4∶1的高水充填材料与矸石胶结充实接顶,逐巷有序充填回收矿柱。为评估充填体力学性能,进行现场取样并开展实验测试。结果表明:充填体单轴抗压强度为2.84MPa,可有效支撑顶板,弱化矿柱应力集中程度,提高采场稳定性。本技术可安全回收矿柱,将矿石采出率提高至81%,同时能有效控制采后覆岩活动,且充填成本低,技术经济效益显著。

国内深水气田首次降压开采应用实践

在深水气田开发过程中,随着天然气的采出,气藏能量逐渐衰减,导致气田产量逐渐下降,难以满足下游需求。为了提高气田采收率,南海某深水气田新增湿气压缩机流程,并同时采用降低深水气田登陆平台整体压力的方式,有效提高了气田采收率。该深水气田降压开采是国内深水气田首次实施降压生产,在实施中操作人员创新性地开发了在线切换流程降压模式,并应用了先进的工业模拟软件OLGA,避免了停产降压对下游用户影响,避免了深水海管泄压放空的能源浪费,避免了对新增设备的损害,避免了平台意外关停。最终,该深水气田的降压生产取得了较好的效果,对国内其他深海气田开发有较高借鉴意义。

比值分析仪在硫磺回收装置中的应用

介绍了H2S/SO2比值分析仪在某公司3套硫磺回收装置的使用情况,阐述了AMETEK 880NSL紫外光度法分析仪的检测原理、系统结构和使用注意事项,分析了近期比值分析仪发生的2起故障,同时针对目前分析仪在使用过程中存在的管理及技术问题,从备品备件管理、在线状态监控、取样伴热改进3个方面提出了改善建议,确保比值分析仪平稳、长周期、高效运行。

床旁超声测量膈肌移动度指导学龄前儿童全麻术后拔管的探讨

目的探讨床旁超声测量膈肌移动度对学龄前儿童全麻术后深麻醉拔管的指导意义。方法入选2020年1月-2022年12月收住曲靖市第一人民医院行全麻气管插管四肢手术的学龄前患儿97例,根据患儿拔管结局分为拔管后无并发症组(C组)和拔管后有并发症组(F组),记录患儿临床资料,床旁超声测量术前、术后自主呼吸恢复时、拔管后即刻、拔管后10min、20min、30min的膈肌移动度,及相应时间点的患儿生命体征、潮气量,围术期呼吸相关并发症发生情况、Ramsay镇静评分,手术时间和复苏室停留时间。对比2组间观察数据的差异,绘制术后各时间点膈肌移动度恢复比率的受试者工作曲线。结果2组间基线资料无显著性差异(P均>0.05)。术后自主呼吸恢复时、气管拔管即刻、拔管后10min、20min膈肌移动度及恢复比率比较均有统计学差异(P<0.05),自主呼吸恢复时膈肌移动度恢复比率的曲线下面积最大(AUC=0.69,P=0.003),灵敏度81.8%,特异度58.1%。拔管时膈肌移动度恢复比率的曲线下面积次之(AUC=0.68,P=0.006),灵敏度95.5%,特异度38.7%。结论围术期借助床旁超声动态评估患儿膈肌功能恢复情况,辅助术后深麻醉拔管决策具有简便、无创、无辐射等优点,有助于早期发现和诊断膈肌功能障碍,改善患儿预后。

恒浓点与水硫比

恒浓点是一系列的,共沸点只是其中之一。恒浓点为水逃逸性转折点、酸腐蚀性分界点。水硫比是H_(2)O与SO_(3)分子数量的比值,统一了气体与硫酸浓度间的关系。相对水硫比为气液平衡状态下的气相水硫比与硫酸中的水硫比之比值,随硫酸温度升高呈扇状展开。在恒浓点相对水硫比等于1;硫酸浓度低于恒浓点时相对水硫比大于1,酸中H_(2)O易逃逸;硫酸浓度越过恒浓点则相对水硫比小于1,SO_(3)更易逃逸,酸中H2O与SO_(3)的化学键弱于H_(2)O与H_(2)SO_(4)间的氢键。酸热回收第2级流下的酸与1级上塔酸混合呈区域不均,2级酸多处相对水硫比上移、气中水分含量大增而引起空间冷凝。半干法制酸用吸湿塔去除水汽,再由吸收塔完成吸收。湿法制酸亦可用两个填料塔——先吸收再吸湿。图示了两种工艺的相对水硫比与硫酸温度的关系,半干法与湿法制酸间是质的不同。

New Scheme of Roadway Layout in Longwall Top-Coal Caving System

Based on mining design theory and practice, a production system of stagger-arrangement roadway in thick seams is put forward for the first time. The system can comprehensively solve the problems in longwall top-coal caving system, such as raising recovery ratio, discharging gas, preventing spontaneous combustion and improving the upkeep of roadway etc.

Low gas-liquid ratio foam flooding for conventional heavy oil

The recovery of heavy oil by water flooding is 10% lower than that of conventional crude oil, so enhanced oil recovery （EOR） is of great significance for heavy oil. In this paper, foam flooding with a gas-liquid ratio （GLR） of 0.2：1 for the Zhuangxi heavy oil （325 mPa.s at 55 ℃） was performed on cores, sand packs and plate model. In sand pack tests, polymer enhanced foam flooding increased oil recovery by 39.8%, which was 11.4% higher than that for alkali/surfactant/polymer （ASP） flooding under the same conditions. Polymer enhanced foam flooding in plate models shows that the low GLR foam flooding increased oil recovery by about 30%, even when the extended water flooding was finished at 90% water cut. Moreover, it was discovered by microscopy that foam was more stable in heavy oil than in light oil. These results confirm that low GLR foam flooding is a promising technology for displacing conventional heavy oil.

Process optimization of a closed-chamber distillation system for the recovery of FLiNaK molten salt

Low-pressure distillation has been proposed as a suitable technique for the recovery of carrier salt from molten salt reactor spent fuel.A closed-chamber distillation system,in which the pump is stopped and pressureinduced salt distillation is performed,was arranged for fluoride salt treatment.A stair-step optimization process was demonstrated to improve the recovery efficiency by up to 99%.The pressure change curve was feasible for estimating the distillation process,and a method for displaying the pressure value online in order to determine the endpoint was also developed.The decontamination factor of Nd in the condensate salt was deduced to be greater than 100 with 1 wt%NdF3–FLiNaK distillation.The optimal conditions developed in this study showed a high recovery ratio for the fluoride carrier salt and a high separation efficiency for rare earth products.

Radial Compressive Property of Nerve Regeneration Conduit with PGLA Biodegradable Fibers

Radial compressive property greatly influences nerve regeneration and functional recovery. In this study,four types of braided bioabsorbable nerve regeneration conduits made from poly(glycolide-co-L-lactide)(PGLA) were produced. The aim is to test the radial compressive force and elastic recovery ratio of nerve regeneration conduits. The results indicated that radial compressive force was closely related to the inner diameter and length of tubes and elastic recovery ratio was nearly unaffected by these two factors.