ESTIMAING AMOUNT OF EXPLOSIVE FOR FRACTURE PLANE CONTROL BLASTING WITH NOTCHED BOREHOLES

With the development of fracture mechanics,the fracture plane control blasting with notched borcholes hascome into being.This technique is used to create a satisfactory presplit along the contour of an excavation inrock.However,the amount of explosive loaded in each hol usually is determined by trial and error.Because ofthis,two approaches estimating the amount of explosive for the blasting technique are suggested.

Research on control method for machining non-cylinder pin hole of piston

The control method for machining non-cylinder pin hole of piston was studied systematically. A new method was presented by embedding giant magnetostrictive material (GMM) into the tool bar proper position. The model is established to characterize the relation between control current of coil and deformation of tool rod. A series of tests on deformation of giant magnetostrictive tool bar were done and the results validated the feasibility of the principle. The methods of measuring magne- tostrictive coefficient of rare earth GMM were analyzed. The measuring device with the bias field and prestress was designed. A series of experiments were done to test magnetostrictive coefficient. Experimental results supplied accurate characteristic pa- rameter for designing application device of GMM. The constitution of the developed control system made up of displacement detection and temperature detection for thermal deformation compensation was also introduced. The developed machine tool for boring the non-cylinder pin hole of piston has the micron order accuracy. This control method can be applied to other areas for machining precision or complex parts.

Effectiveness analysis of methane-drainage by deep-hole controlled pre-splitting blasting for preventing coal and gas outburst

In the study of the application effectiveness of deep-hole controlled pre-splittingblasting technology,it was found through laboratory micro test and field study on a mine insouth China that under the technology,coal masses produce many irreversible cracks.Afterblasting,the nearer the distance from blasting hole,the larger the BET surface areaand volume ratio of the infiltration pore are;they increased by 11.47%and 5.73%,respectively.The coefficient of air permeability is increased 4 times.After 3 months,the gasdrainage rate was increased by 66%.In the first 15 days,the cumulative pumped gas was1.93 times of blasting before.The average absolute gas emission decreased by 63.46%.Experimental results show that deep-hole controlled pre-splitting blasting not only preventscoal and gas outburst,but also gives good economic results.

The Precise Methods for the Measurement of Collimator Hole Angulation and Center of Rotation of SPECT by Adaptive Quality Control Phantom

The Adaptive Quality Control Phantom (AQCP) is a computer-controlled phantom which positions and moves a radioactive source in the Field of View (FOV) of an imaging nuclear medicine device on a definite path to produce a spatial distribution of gamma rays to perform QC Tests such as the Collimator Hole Angulation (CHA) and the Center of Rotation (COR) of Single Photon Emission Computer Tomography (SPECT). The collimator hole angulation for six collimators was measured using a point source and a computer-controlled cylindrical positioning system. In this method, the displacement of the image of a point source was examined as the AQCP was moving point source vertically away from the collimator face. The results of the high-accuracy measurement method of CHA show that the measurement accuracy for absolute angulation errors is better than ±0.024°. The Root Mean Square (RMS) of CHA for LEHR, LEHS and LEUHR collimators of SMV dual heads camera and LEGP, MEGP and HEGP of GE Millennium MG were evaluated to be 0.290°, 0.292°, 0.208°, 0.154°, 0.220° and 0.202°, respectively. It is to be added in this connection that the evaluated RMS of CHA for LEHR collimator with the distance variation from the collimator’s surface ±1 mm has been varied ±0.04 degree. A new method for the center of rotation assessment by AQCP is introduced and the results of this proposed method as compared with the routine QC test and their differences are discussed in detail. We defined and measured a new parameter called Dynamic Mechanical Error (DME) for applying the gantry motion correction.

Results of the Measurement of the Collimator Hole Angulation for Different Collimators of SPECT with Adaptive Quality Control Phantom

The Adaptive Quality Control Phantom (AQCP) is the computer-controlled phantom which positions and moves a radioactive source in the Field of View (FOV) of an imaging nuclear medicine device on a definite path to produce any spatial distribution of gamma rays to perform the QC Tests such as the Collimator Hole Angulation (CHA) of Single Photon Emission Computer Tomography (SPECT). The collimator hole angulation for seven collimators were measured with the method by using a point source and computer-controlled cylindrical positioning. In this method the displacement of the image of a point source examined as the AQCP move point source vertically away from the collimator face. The results of the high-accuracy measurement method of CHA show that the measurement accuracy for absolute angulation errors is better than ±0.024°. The Root Mean Square (RMS) of CHA for LEHR, LEHS, LEUHR, MEGP-250, MEGP-300, MEGP-360 and HEPH collimators of SMV dual heads camera were measured to be 0.290°, 0.292°, 0.208°, 0.194°, 0.181°, 0.177°, 0.150°, respectively. The Root Mean Square (RMS) of CHA for LEGP, MEGP and HEGP collimators of GE Millennium MG were measured to be 0.154°, 0.220° and 0.202° respectively. It is to be added in this connection that the measured RMS of CHA for LEHR collimator with the distance variation from the collimator’s surface +/– 1 mm has been varied +/– 0.04 degree.

Vertical cavity surface emitting laser transverse mode and polarization control by elliptical hole photonic crystal

The polarization of traditional photonic crystal(PC) vertical cavity surface emitting laser(VCSEL) is uncontrollable,resulting in the bit error increasing easily.Elliptical hole photonic crystal can control the transverse mode and polarization of VCSEL efficiently.We analyze the far field divergence angle,and birefringence of elliptical hole PC VCSEL.When the ratio of minor axis to major axis b/a = 0.7,the PC VCSEL can obtain single mode and polarization.According to the simulation results,we fabricate the device successfully.The output power is 1.7 mW,the far field divergence angle is less than 10°,and the side mode suppression ratio is over 30 dB.The output power in the Y direction is 20 times that in the X direction.

PROBE-HOLE FIELD EMISSION MICROSCOPE SYSTEM CONTROLLED BY COMPUTER

A probe-hole field emission microscope system,controlled by the Apple Ⅱ computer,has been developed and operated successfully for measuring the work function of a single crystalplane.The detection screen,the phototube and the amplifier are combined for measuring theprobe-hole current.The combination is calibrated and the calibrated data are used in the com-puter program.The high voltage on the viewing screen is adjusted by using a D/A converter.The total current and the probe-hole current are acquired by using an A/D converter.A programin BASIC is used for processing all data and the Fowler-Nordheim plot parameters are given.Work functions of single crystal planes can then be calculated;as examples,the work functionson the clean W(100)and W(111)planes are measured to be 4.67 eV and 4.45 eV,respectively.

Mechanism and practice of rock control in deep large span cut holes

Deep large span cut holes are difficult to stabilize. The 7801 cut hole in the Lu'an Wuyang Mine was used as this project's background. The main factors affecting large span cut hole stability are analyzed. Pre- stressed bolting theory was used to design a roof control method for a large span roadway. By reducing the span and applying equal strength coordinated supports the rock could be stabilized. The control prin- ciples and methods are given herein along with the analysis. A double micro arch cross section roadway is defined and its use in solving the current problem is described. Beam arch theory was used to build a model of the double micro arch cross section roadway. A support reverse force model for the arch foot intersection was also derived. A support method based upon reducing the width of the large span in the cut hole is presented. These results show that the reduced span of the roadway roof plus the use of cable anchors and single supports gives an effective way to control the large span cut hole. On site monitoring showed that the reduced span support from the double micro arch cross section roadway design had a significant effect. The roadway surface displacement was small and harmful deformation of the cut hole was effectively controlled. This will ensure its long term stability.

煤矿井下三段式自动封孔器结构设计

针对传统封孔器自动化程度低和现有自动封孔器安全性低、封孔器下放与注料不连续等问题,分析了自动封孔器的功能需求与安全需求,提出三段式自动封孔器方案。设计了封孔器同轴接扣机构、钻孔封堵机构、自动注料流道和动密封机构等关键机构。制作样机并开展了室内封孔实验。实验显示,钻孔封堵机构可自动封堵模拟钻孔,封孔料可自动注入模拟钻孔中完成封孔,三段式自动封孔器方案合理,具有可行性。

CFRP制孔过程中轴向力自适应控制仿真及实验研究

钻削轴向力的大小和碳纤维增强树脂基复合材料(Carbon fiberrein-forced plastic, CFRP)制孔质量的好坏密切相关,为合理调控轴向力来减少制孔缺陷,开展了CFRP制孔过程中轴向力的自适应控制仿真及实验研究。首先,开展CFRP钻削试验,对轴向力及制孔质量进行了定量研究。其次,根据CFRP钻入、稳定钻削及钻出阶段不同加工特性建立了轴向力三阶段模型。最后,基于模糊逻辑及所建模型进行了轴向力自适应控制仿真及实验研究。结果表明:利用模糊逻辑控制算法结合CFRP加工特性,对制孔过程中轴向力进行智能调控是可行的;此外,根据仿真信息调控轴向力可有效降低制孔缺陷、提升孔壁质量。该研究为大厚度碳纤维复合材料制孔过程中轴向力的智能调控提供了新的思路。

周边眼偏位空孔爆破设计优化研究与应用

依据已有研究对空孔效应和设置空孔时裂纹扩展规律进行探讨,发现空孔有利于裂纹贯通,对提升爆破效果有一定帮助,但也发现传统的直线型空孔布置会导致裂纹偏向,即在空孔附近转向、偏离原发展路径,影响原设计开挖轮廓。若设置偏位空孔,则可充分利用空孔效应及导向作用以提高开挖质量。对于偏位空孔在爆破中的效应,采用数值模拟研究了不同炮孔间距、空孔偏位角下的裂纹扩展规律和炮孔间贯通情况,探讨了最优偏位角度设计,并根据模拟结果对现场爆破方案进行优化,研究实际应用效果。研究结果表明:偏位空孔对爆生裂纹具有较直线空孔更明显的导向作用,主要表现在爆生裂纹尖端向空孔本身发展或被空孔裂纹引导偏向、最终主裂纹与空孔连通或在空孔范围之外主裂纹相贯通,更利于炮孔主裂纹扩展与贯通;通过提取模拟结果并测量裂纹范围,对于孔间距在60 cm及以下时,适用于周边眼爆破设计的最优偏位角为15°,在此情况下炮孔连线方向形成了与孔心连线相平行的裂纹,能显著提升贯通效果;对于优化后的福厦铁路某隧道爆破施工方案,通过振速监测及超欠挖断面扫描分析,发现周边眼起爆引起的爆破振速降低了超过50%,超欠挖值也由平均25 cm降低至15 cm以内,整体应用效果良好。该项研究可为隧道爆破减振及超欠挖控制研究提供一定参考。

一种能量均衡的水下无线传感器网络覆盖空洞修补方法

针对现有水下无线传感器网络空洞修补方法需要空洞边界探测、通信和计算开销大、覆盖率和能量均衡性差、水下环境模型过于理想化等问题,考虑水底地形复杂,且通常存在较大障碍物等环境因素,建立了基于能量的节点之间、区域边界、零能量空洞、低能量覆盖洞、水底地形及障碍物作用力等多维度的虚拟力模型,提出了基于上述虚拟力模型和能量均衡的空洞修补算法。该算法不需要精确的空洞边界探测,对水下复杂地形和不同环境具有良好的适应性和鲁棒性。此外,提出的对低能量节点、低能量覆盖洞冗余修补的策略,显著提高了修补后网络能量分布的均衡性,减少了因低能量节点的能量很快耗尽而出现新的覆盖空洞的频率,减少了空洞修补频次,降低了网络维护成本。

青龙煤矿底板定向钻孔施工分析

针对贵州青龙煤矿低透气性煤层,在21605底抽巷设计底板穿层定向钻孔,进行16#煤层治理瓦斯。首先,根据钻遇地层情况,确定定向钻孔在底板的开孔层位,然后通过分析在施工定向钻孔中出现的问题,对定向钻孔的最初设计进行优化,确保定向钻孔施工顺利,进入目标煤层,并在目标煤层中得到有效延伸,从而进行瓦斯抽采。通过本次施工可知,只有定向钻孔在目标煤层中有效延伸,才可减少抽采盲区,以达到瓦斯治理的效果,为煤矿安全掘进提供保障。

基于力控技术的航空整体加强框自适应定位方法研究

为了减弱制造差异对航空整体加强框装配定位质量的影响,解决强迫定位造成的定位过程管控性差和定位结果复现度低的难题,基于力控技术提出一种航空整体加强框自适应定位方法,按传统强迫方式完成装配定位后,在设计允许范围内调整若干坐标定位孔位置,至孔位处力载值满足自适应定位要求。针对航空整体加强框装配定位工艺对形位精度、装配应力水平的要求,量化装配定位质量评价标准,基于正交试验分析定位孔处力载绝对平均值和定位检测点处应力绝对平均值的变化规律,进行装配现场易于获取的力载值取代应力值的可行性研究,通过修正装配定位质量评价标准量化公式得到坐标定位孔处力载调整目标,指导航空整体加强框装配定位。

基于高斯展开法的碟形声学黑洞宽频调谐减振机理研究

近年来,嵌入式声学黑洞(acoustic black holes,ABH)以其优异的性能,在结构减振降噪、声波调控、能量回收等领域展示了广阔的应用前景,但其局部结构强度弱化会影响其工程实用性。提出一种碟形声学黑洞(dish-shaped acoustic black hole,DABH)结构,将其附加在主体结构上,以实现对主体结构的宽频减振。在Rayleigh-Ritz法框架下,选择高斯函数作为基函数,根据声学黑洞板的形状确定基函数的分布,避免质量和刚度矩阵的奇异化,建立了其耦合系统半解析模型。通过与有限元模态分析结果的对比,验证了半解析建模方法的正确性。研究了碟形声学黑洞结构参数以及连接位置对主体结构振动响应特性的影响规律,分析了碟形声学黑洞的ABH效应以及与主体结构的耦合效应,揭示了其宽频调谐减振的机理,为拓展声学黑洞在宽频结构振动控制上的应用提供了新的思路。

伊拉克Missan油田BU区块钻遇盐膏层超高压流体圈闭的钻井技术探讨

伊拉克Missan油田复合盐膏层段含高压盐水层,其中BU区块某井12-1/4"井段钻遇含有超高压流体圈闭,使得本井段作业无安全钻井液密度窗口,作业中气侵、盐水溢流、井漏、缩径等井下复杂频出。后续钻进期间采取严格的ECD控制技术,简化钻具组合并优化参数;非钻进期间分层浆柱稳定井眼,分段控制起下管柱速度等措施,避免了局部超高压流体地层导致的涌、漏、卡等井下复杂,保障了井眼作业安全,积累了油田内相同井况的作业经验,同时也为其他油田同类地层提供了作业思路。

基于多方向导纳力控制的机器人柔顺装配系统

针对轴孔装配过程中遇到卡阻或楔紧现象导致接触力过大损坏工件的问题,提出一种基于导纳力控制的机器人柔性装配系统。将轴孔装配过程为搜孔阶段和调整插入阶段。首先,搜孔阶段提出一种基于阿基米德螺旋线的搜孔策略。其次,调整插入阶段提出一种基于等效质量–阻尼–弹簧的多维方向的导纳力控制装配方法。最后,选取圆形轴孔开展实际装配实验,结果表明所提出的方法能够实现机器人柔顺插孔,达到了预期效果。

起伏薄煤层顺层孔工艺研究

我国南方地区的煤层赋存条件复杂,煤层较薄,倾角变化大,常规钻进工艺无法有效完成工作面顺层孔施工要求,存在抽采空白带。为了消除肥田矿111601工作面抽采盲区,在111601工作面进行顺层孔施工工艺试验研究。试验采用扶正器保直钻具组合和定向钻进2种施工工艺,根据钻孔轨迹分析了偏移规律及煤层赋存条件。现场试验表明,单一的保直钻具组合无法满足消除抽采盲区的目的;定向钻进工艺能通过分支孔施工,适应煤层起伏,使钻孔从一侧覆盖整个工作面宽度,有效消除了工作面中部抽采盲区,对于后续该工作面抽放钻孔施工具有指导作用。

有限空间新建设施基坑开挖沉降特征及小变形控制

针对有限空间新建基坑变形控制难题,采用理论分析、数值推演和工程实践相结合的研究方法,建立了考虑应力释放的有限空间夹持力学模型,推导了夹持应力与地层损伤因子的函数关系,研究了应力释压孔对有限空间地层应力的影响特征,提出了变形支挡–应力阻隔一体结构控制方法,并通过北京科技大学工程实践基地(二期)验证该方法的有效性.结果表明,地层损伤因子与夹持应力呈线性负相关关系,随开挖深度逐渐增大,布设释压孔可有效降低有限空间夹持应力,释压孔有利于调整地层夹持应力和控制地层变形,变形控制率为33.48%~58.72%,且变形支挡–应力阻隔一体结构控制方法的水平变形控制率为28.57%~37.91%,地层沉降变形控制率为36.86%~54.26%,与数值模型计算结果趋势相同,论证了理论分析和数值推演结果有效性,为有限空间基坑稳定性控制提供数据支撑.

集聚式多锚头钢横梁制造工艺研究

池州长江公路大桥主塔采用花瓶形,塔柱间钢横梁采用集聚式多锚头箱形结构,每个钢横梁上最多有10对锚固点(20个锚头)。通过对集聚式多锚头钢横梁的结构特点分析,确定了合理的横梁块体组装焊接顺序;通过焊接工艺评定试验确定了与母材匹配的焊接材料和焊接参数,保证了焊缝质量;通过对拼装胎架、锚箱精度控制、焊接变形控制等关键项点研究和有效技术措施的应用,确保钢横梁的外形尺寸符合标准和规范要求;先孔法栓接技术的实施,可大幅提高桥位钢横梁拼装效率。