Experimental investigation of methane explosion fracturing in bedding shales:Load characteristics and three-dimensional fracture propagation

Methane in-situ explosion fracturing(MISEF)enhances permeability in shale reservoirs by detonating desorbed methane to generate detonation waves in perforations.Fracture propagation in bedding shale under varying explosion loads remains unclear.In this study,prefabricated perforated shale samples with parallel and vertical bedding are fractured under five distinct explosion loads using a MISEF experimental setup.High-frequency explosion pressure-time curves were monitored within an equivalent perforation,and computed tomography scanning along with three-dimensional reconstruction techniques were used to investigate fracture propagation patterns.Additionally,the formation mechanism and influencing factors of explosion crack-generated fines(CGF)were clarified by analyzing the morphology and statistics of explosion debris particles.The results indicate that methane explosion generated oscillating-pulse loads within perforations.Explosion characteristic parameters increase with increasing initial pressure.Explosion load and bedding orientation significantly influence fracture propagation patterns.As initial pressure increases,the fracture mode transitions from bi-wing to 4–5 radial fractures.In parallel bedding shale,radial fractures noticeably deflect along the bedding surface.Vertical bedding facilitates the development of transverse fractures oriented parallel to the cross-section.Bifurcation-merging of explosioninduced fractures generated CGF.CGF mass and fractal dimension increase,while average particle size decreases with increasing explosion load.This study provides valuable insights into MISEF technology.

Numerical simulations and comparative analysis of two- and three-dimensional circulating fluidized bed reactors for CO2 capture

Carbon dioxide(CO2),the main gas emitted from fossil burning,is the primary contributor to global warming.Circulating fluidized bed reactor(CFBR)is proved as an energy-efficient method for post-combustion CO2 capture.The numerical simulation by computational fluid dynamics(CFD)is believed as a promising tool to study CO2 adsorption process in CFBR.Although three-dimensional(3D)simulations were proved to have better predicting performance with the experimental results,two-dimensional(2D)simulations have been widely reported for qualitative and quantitative studies on gas-solid behavior in CFBR for its higher computational efficiency recently.However,the discrepancies between 2D and 3D simulations have rarely been evaluated by detailed study.Considering that the differences between the 2D and 3D simulations will vary substantially with the changes of independent operating conditions,it is beneficial to lower computational costs to clarify the effects of dimensionality on the numerical CO2 adsorption runs under various operating conditions.In this work,the comparative analysis for CO2 adsorption in 2D and 3D simulations was conducted to enlighten the effects of dimensionality on the hydrodynamics and reaction behaviors,in which the separation rate,species distribution and hydrodynamic characteristics were comparatively studied for both model frames.With both accuracy and computational costs considered,the viable suggestions were provided in selecting appropriate model frame for the studies on optimization of operating conditions,which directly affect the capture and energy efficiencies of cyclic CO2 capture process in CFBR.

Influence of bed elevation discordance on flow patterns and head losses in an open-channel confluence

Confluences play a major role in the dynamics of networks of natural and man-made open channels, and field measurements on river confluences reveal that discordance in bed elevation is common.Studies of schematized confluences with a step at the interface between the tributary and the main channel bed reveal that bed elevation discordance is an important additional control for the confluence hydrodynamics.This study aimed to improve understanding of the influence of bed elevation discordance on the flow patterns and head losses in a right-angled confluence of an open channel with rectangular cross-sections.A large eddy simulation (LES)-based numerical model was set up and validated with experiments by others.Four configurations with different bed discordance ratios were investigated.The results confirm that, with increasing bed elevation discordance, the tributary streamlines at the confluence interface deviate less from the geometrical confluence angle, the extent of the recirculation zone (RZ) gets smaller, the ratio of the water depth upstream to that downstream of the confluence decreases, and the water level depression reduces.The bed elevation discordance also leads to the development of a large-scale structure in the lee of the step.Despite the appearance of the large-scale structure, the reduced extent of the RZ and associated changes in flow deflection/contraction reduce total head losses experienced by the main channel with an increase of the bed discordance ratio.It turns out that bed elevation discordance converts the lateral momentum from the tributary to streamwise momentum in the main channel more efficiently.

A computational particle fluid-dynamics simulation of hydrodynamics in a three-dimensional full-loop circulating fluidized bed: Effects of particle-size distribution

A computational particle fluid-dynamics model coupled with an energy-minimization multi-scale(EMMS)drag model was applied to investigate the influence of particle-size distribution on the hydrodynamics of a three-dimensional full-loop circulating fluidized bed.Different particle systems,including one monodisperse and two polydisperse cases,were investigated.The numerical model was validated by comparing its results with the experimental axial voidage distribution and solid mass flux.The EMMS drag model had a high accuracy in the computational particle fluid-dynamics simulation of the three-dimensional full-loop circulating fluidized bed.The total number of parcels in the system(Np)influenced the axial voidage distribution in the riser,especially at the lower part of the riser.Additional numerical simulation results showed that axial segregation by size was predicted in the two polydisperse cases and the segregation size increased with an increase in the number of size classes.The axial voidage distribution at the lower portion of the riser was significantly influenced by particle-size distribution.However,radial segregation could only be correctly predicted in the upper region of the riser in the polydisperse case of three solid species.

NUMERICAL INVESTIGATION OF THREE-DIMENSIONAL FLOW AND BED SHEAR STRESS DISTRIBUTION AROUND THE SPAN SHOULDER OF PIPELINE

Three-dimensional flow around a pipeline span shoulder is simulated using afractional step finite element method. The Reynolds number, based on the pipe-diameter and theapproaching flow velocity, is set at 500 and 5 x 10~5 to simulate both laminar and turbulent flow.In high Reynolds number case, Smagorinsky SGS closure is used to model the turbulent flows. The flowfield visualization by vorticity iso-surfaces shows that a spiral vortex tube is formed around thespan shoulder and extends around the span shoulder. The vortex cores defined by the eigenvalues ofthe symmetric tensor S^2 + Ω~2 (S and Ω are respectively the symmetric and antisymmetric parts ofthe velocity gradient tensor) gives more details of the flow field. It is also found that there aresignificant bed shear stress concentrations in the span shoulder area. The reasons for the shearstress concentration are discussed.

A three-dimensional k-ε-k_p model in curvilinear coordinates for sediment movement and bed evolution

To aim at the substitution of the magnitude and direction of water flow movement near bed for those of bed load transport in solid-liquid two-phase one-fluid model, and to simulate the effect of secondary flow on transverse bed load transport in channel bends and the effect of bed slope on bed load trans- port in a better way, a three-dimensional k-ε-kp solid-liquid two-phase two-fluid model in curvilinear coordinates is solved numerically with a finite-volume method on an adaptive grid for studying wa- ter-sediment movements and bed evolution in a 120° channel bend. Numerical results show that the trajectories of solid-phase deviate from those of liquid-phase in the channel bend, and the deviation increases with the increase of the particle diameters. The calculated bed deformation by the k-ε-kp model is in better agreement with measured bed deformation than those by one-fluid model. It is proved that the k-ε-kp model can simulate the effect of secondary flow on lateral bed load transport with the higher accuracy than the one-fluid model.

Treatment of 73 Cases of Bed Sores with Warming Moxibustion

Seventy-three patients with bed sores were treated by warming moxibustion. Of the 73 cases, 58 cases were cured, 12 cases improved and 3 cases ineffective, with an effective rate of 95.9%.

Three-dimensional heat transfer in a particulate bed in a rotary drum studied via the discrete element method

We simulated three-dimensional heat transfer inside a horizontal rotating drum using the discrete element method and a thermal conduction model.The aim was to determine the effect of end-wall heating on thermal behavior of a granular bed.The simulation showed that the end-wall heating significantly affects the axial temperature profile of the bed,particularly when the length-to-diameter ratio is low.Particles near the wall heated faster and became more thermally uniform than those in the center of the drum.The region affected by the end heating gradually increased over time.Increasing the rotation speed enhanced the heat conduction rate,and increasing the fill level reduced the mean temperature and thermal uniformity of the granular bed.Heat transfer was also simulated for drums with different length-to-diameter ratios.

隔药灸脐法对原发性痛经患者下腹部疼痛及额外卧床时间的影响

目的观察隔药灸脐法对原发性痛经患者下腹部疼痛时间、疼痛程度、额外卧床时间的影响。方法将符合纳入标准的75名原发性痛经患者随机分为隔药灸脐组、隔淀粉灸脐组、针三阴交组,每组各25例,采用COX痛经症状量表评价3组患者治疗前、第1、2、3月经期及随访期下腹部疼痛情况及疼痛引起的额外卧床时间。结果第2、3月经期,隔药灸脐组对下腹部疼痛时间及疼痛程度改善优于隔淀粉灸脐组和针三阴交组（P〈0.05-0.01）;对额外卧床时间的改善优于针三阴交组（P〈0.01）。随访期隔药灸脐组对下腹部疼痛时间及疼痛程度、额外卧床时间的改善优于隔淀粉灸脐组和针三阴交组（P〈0.05-0.01）。结论隔药灸脐组对原发性痛经患者下腹部疼痛时间及疼痛程度、额外卧床时间改善明显,且远期疗效较好。

艾灸器具研究进展

介绍了国内艾灸器具的发展现状,重点从器具的主要构成、性能、特征等方面对温控、烟控、多功能、多方位精准、床式、尬灸部位等类型的灸具进行了归纳整理。指出了新型灸具改善了传统艾灸方式的弊端但同时也存在一定的不足,提出研制一种实用性强且利于推广的灸具是未来的发展方向。

自制艾灸床薰灸治疗原发性痛经的临床研究

目的:研究自制艾灸床薰灸治疗原发性痛经临床疗效。方法:40例原发性痛经患者随机分为治疗组20例,对照组20例,分别对河车路阙极段进行艾灸治疗,治疗组运用艾灸床用8段直径18 mm、长50 mm艾柱放于艾灸托盘上进行薰灸治疗,对照组运用4支直径18 mm、长200 mm艾条捆绑成一柱进行传统悬灸治疗,3个疗程后观察两组资料的临床疗效。结果:治疗组总有效率为70%,对照组总有效率为55%,两组间比较无统计学差异P>0.05。结论:自制艾灸床薰灸治疗可替代传统悬灸治疗原发性痛经,前者艾烟少,灸感传导快,患者舒适易于接受,操作简单方便,不需手持,而且具有药力峻、火力猛、渗透力强、灸疗面广等特点,有推广普及价值。

电控多部位艾灸床的设计与应用

设计一种可广泛应用于人体各部位及关节艾灸的电控艾灸床,主要结构包括床板和艾灸箱。床板装在四角的支撑脚上,床板上开有若干与人体部位相对应的透气通道,床板下面装有开口朝向透气通道的艾灸箱;艾灸箱内装有水平的艾条固定网,网下设有电控推杆,可根据需要调节艾条与艾灸部位的距离;艾灸箱上部两侧壁配有卡体,卡体置于床板下面的活动卡槽内,构成可拆卸结构。电控多部位艾灸床设计科学、制作简单、结构合理、操作方便、使用安全,可对人体多个部位施灸,艾灸效果好,舒适无烟,且可根据需要调节灸箱内艾条的高度,具有较高的推广价值。

艾灸床艾灸督脉、肩井治疗肩背痛临床研究

目的:观察艾灸床艾灸督脉、肩井治疗肩背痛的临床疗效,并调查患者的满意度。方法:纳入122例肩背痛患者,于艾灸床艾灸患者背部督脉上的大椎、至阳、身柱、灵台穴及肩部的肩井穴,对患者治疗前后的肩背疼痛、颈肩压痛和肩背活动进行评分,并统计以上3项症状的出现率,调查患者对艾灸床艾灸治疗的满意度。结果:患者经艾灸床艾灸治疗后肩背疼痛、颈肩压痛和肩背活动评分均较治疗前降低,差异均有统计学意义(P<0.05)。治疗后,患者肩背疼痛缓解总有效率100%,颈肩压痛缓解总有效率97.4%,肩背活动缓解总有效率97.1%。经艾灸床治疗后,患者的总满意率为99.2%。结论:艾灸床艾灸督脉及肩井治疗肩背痛疗效显著,患者对治疗的满意度高,值得临床推广应用。

医用艾灸床的创新设计研究

随着老龄化现象的不断加剧,人们的身体状况不容乐观,艾灸作为中国传统中医治疗方式被广泛使用,而社会的发展以及医疗设备产品的激增却依旧没有改善艾灸传统的操作方式,艾灸时依旧存在着(烫伤、灼伤、意外受伤等)极大的安全隐患以及给操作者带来很大程度上的肌肉疲劳,市场上现有艾灸床大多只用于美容保健场所,专用于医疗的少之又少,文章主要以改善传统的艾灸方式,结合舒适的交互体验,设计出一款全新的医用艾灸床,一方面给患者提供一种安全的治疗方式,提高艾灸效果,缓解艾灸时疼痛。另一方面减少了医护人员的肌肉负担。

艾灸长强穴防治家庭病床脑卒中患者的便秘效果

目的 :探讨艾灸长强穴防治家庭病床脑卒中患者便秘效果。方法 :选取2011年1月至2013年12月彭浦社区家庭病床脑卒中患者63例,随机分为观察组32例,行艾灸长强穴结合家庭病床常规护理干预,灸时每次20 min,隔日1次,10次为1个疗程,共2个疗程;对照组31例,行常规护理干预。两组便秘改善情况采用症状积分法评估。结果:观察组总有效率为93.75(30/32),明显优于对照组的83.87%(26/31,P<0.05)。观察组在排便费力、粪便性状、排便不尽感、肛门直肠堵塞感、自发性排便次数及便秘总评分方面均优于对照组(P均<0.05)。结论 :艾灸长强穴能有效防治家庭病床脑卒中患者便秘,进而改善患者生活质量。

一种全自动艾灸仪的研制与应用

目的研究并开发利用电脑控制治疗床来改变艾灸头到艾灸穴位皮肤的距离,艾灸头自动找寻艾灸穴位,仿人工艾灸,减轻医生的工作负担及增加患者的舒适度。方法中心处理器通过驱动板来控制治疗床的三维移动,用来改变艾灸治疗的穴位及灸头到皮肤的距离,保障排烟系统及灸头不动,从而保障排烟效果和排烟系统的故障率降低。排烟系统采用自然排烟加动力排烟,保障排烟效果。结果与传统艾灸和艾灸仪相比保障治疗效果,减轻医生负担,增加患者舒适度,提高安全系数。结论从设计到样机试制、使用情况来看,这种用于艾灸的设备对艾灸治疗潜力比较大,有待推广。

艾灸床运行过程中表面的温度分析

目的:对艾灸床运行过程中表面的温度进行分析,为实现艾灸床的自动控温提供理论依据和技术指导。方法:将艾灸床铁丝网下20 mm作为测温平面,按照矩阵形式布置30个测温点。调节艾柱托盘与铁丝网之间的距离(包括185、245、295、335 mm),设置艾柱托盘为固定模式或摇摆模式进行艾灸床表面的温度测定。分析艾柱托盘为固定模式时,艾灸床在艾柱托盘与铁丝网不同距离下运行时高温点的位置;选取艾柱托盘在艾灸床铁丝网下185 mm时的数据,分析艾柱托盘设置为摇摆模式和固定模式时艾灸床表面的温度特性;选取11号测温点和17号测温点,分析艾柱托盘为固定模式时,艾柱托盘与铁丝网之间的距离变化对艾灸床表面温度的影响。结果:艾灸床在艾柱托盘与铁丝网不同距离下运行时,高温点呈现集中在腰臀部的特点;相比固定模式,艾柱托盘为摇摆模式时,测温平面的整体温度呈现更加均匀的特点;艾灸床表面的温度随着艾柱托盘与铁丝网之间距离的减小呈现上升的特点。结论:在实现艾灸床自动控温的过程中,将控温设备的温度探头放置在腰臀部位置更为合理;将艾柱托盘设置为摇摆模式能使艾灸床表面均匀受热,艾灸效果更佳;可通过调节艾柱托盘与铁丝网之间的距离来调节艾灸床表面的温度。

Physical model test and application of 3D printing rock-like specimens to laminated rock tunnels

Weak structural plane deformation is responsible for the non-uniform large deformation disasters in layered rock tunnels,resulting in steel arch distortion and secondary lining cracking.In this study,a servo biaxial testing system was employed to conduct physical modeling tests on layered rock tunnels with bedding planes of varying dip angles.The influence of structural anisotropy in layered rocks on the micro displacement and strain field of surrounding rocks was analyzed using digital image correlation(DIC)technology.The spatiotemporal evolution of non-uniform deformation of surrounding rocks was investigated,and numerical simulation was performed to verify the experimental results.The findings indicate that the displacement and strain field of the surrounding layered rocks are all maximized at the horizontal bedding planes and decrease linearly with the increasing dip angle.The failure of the layered surrounding rock with different dip angles occurs and extends along the bedding planes.Compressive strain failure occurs after excavation under high horizontal stress.This study provides significant theoretical support for the analysis,prediction,and control of non-uniform deformation of tunnel surrounding rocks.

自制艾灸床薰灸治疗腰肌劳损的临床研究

目的:研究自制艾灸床薰灸治疗腰肌劳损的临床疗效。方法:50例腰肌劳损患者随机分为治疗组30例、对照组20例,分别对河车命强段进行艾灸治疗,治疗组运用艾灸床用13段Φ18mm×40mm艾柱进行薰灸治疗,对照组运用5支Φ18mm×200mm艾条捆绑成一柱进行悬灸治疗,两组均进行密集拔罐和功能锻炼,1疗程后观察两组资料的临床疗效、灸感传导、治疗感受、操作难易,并进行统计学分析。结果:治疗组显效率为70%,对照组显效率为40%,治疗组显效率明显高于对照组(P<0.05);治疗组患者灸感传导、治疗感受、操作难易明显优于对照组(P<0.01)。结论:自制艾灸床薰灸治疗腰肌劳损疗效明显,灸感出现快,患者舒适易于接受,操作简单方便,具有药力峻,火力猛,渗透力强,灸疗面广等特点,有推广普及价值。