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.

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.

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.

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.

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.

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。

雪峰弧构造带钻孔轨迹控制关键技术研究

随着近年来矿产资源勘查要求的提高,岩心钻孔的深度及地层复杂性也不断加大,为能精准的钻遇靶区矿体以实现地质目的,对钻孔轨迹控制的要求越来越高。雪峰弧构造带部分工作区地层倾角大、软硬交替频繁、地层破碎,实际施工中地层造斜情况严重,随着孔深增加导致终孔轨迹与靶区矿体偏差较大,影响矿产资源勘查的精度和质量。通过对该工作区地层造斜情况的深入分析,在ZK1001钻孔绳索取心钻进施工中采用初级定向孔技术和满眼钻具工艺,大幅度提高了钻孔孔身质量,较好地实现钻孔轨迹控制。并通过试验不同的岩心钻具组合,提出了满眼钻具组合的优化意见和建议,为工作区岩心钻孔轨迹控制提供技术参考。

表面菱形孔795 nm VCSEL的偏振特性

795 nm垂直腔面发射激光器(VCSEL)作为铷基芯片级原子钟(Rb-CSAC)的光源,其输出光的偏振不稳定会降低Rb-CSAC的稳定度和精确度。为了满足Rb-CSAC对795 nm VCSEL偏振稳定的需求,设计了一种具有表面菱形孔的偏振稳定的795 nm VCSEL。通过有限时域差分(FDTD)法计算了VCSEL的偏振特性,结果表明VCSEL的顶部分布式布拉格反射镜(DBR)在表面菱形孔的长轴和短轴方向具有不同的反射率。反射率高的偏振模式阈值增益低,成为VCSEL优先激射的主导偏振模式。为进一步提高VCSEL的偏振抑制比(OPSR),将VCSEL的氧化孔制作成尺寸为5.5μm×4.1μm的菱形。对不同长、短轴的表面菱形孔795 nm VCSEL进行偏振测试,结果表明,当表面菱形孔的尺寸为4μm×6μm,且菱形氧化孔的长轴与表面菱形孔的长轴相互垂直时,VCSEL的OPSR可达到16.22 dB。

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。

软土地层三线小角度叠交盾构隧道施工影响规律及位移控制

天津地铁6号线入出段线盾构隧道上穿既有隧道,通过现场实测和数值模拟对既有隧道结构变形规律、变形影响因素、不同变形控制措施的效果进行了研究。结果表明:盾构上穿过程中既有隧道竖向位移整体呈现出隆起-沉降-隆起的变化规律;刀盘距叠交部位断面距离L=2.0D(D为隧道直径)时,叠交部位断面轴力达到最大值,L=0~2.0D时,叠交部位断面弯矩逐渐由L≤0时的横8字形转变为L≥2.0D时的三叶草形;新建隧道与既有隧道的叠交角度在15°~60°、竖向净距小于1.0D时,既有隧道竖向位移受新建隧道影响较大,实际工程中应使叠交角度大于60°,竖向净距大于1.0D;设置支撑台车后,支撑台车影响范围约为2倍台车长度,在影响范围内横断面位移得到控制,但随着支撑台车离开,原来位置处对位移的控制效果逐渐消失;与不注浆相比,深孔注浆加固后既有隧道竖向位移最大值和水平位移最大值分别减小了67.4%、76.0%。

空位缺陷调控策略构筑高能量密度六方孔洞MXene水系超级电容器

利用碳空位缺陷有序化策略构筑了多层六方孔洞MXene电极材料,在软包超级电容器中实现了高比容量和高能量密度水系钾离子存储。该电极材料具有较大比表面积的三维六方孔洞结构,为储钾提供了更多的活性位点。结合六方孔洞内壁新暴露的钛原子的化合价变化引起的赝电容效应,阐明了多层六方孔洞MXene水系钾离子超级电容器比容量提高的内在原因。通过密度泛函理论计算多层六方孔洞MXene对钾离子的吸附能,并结合电化学储钾性能实验及动力学分析,确定了钾离子被吸附的最佳位置,得出了钾离子的吸附规律。通过定量分析多层六方孔洞MXene中电子的能带结构和差分电荷密度等电子传输规律,揭示了其水系钾离子超级电容器具有高电导率和良好倍率性能的内在机理。

基于力柔顺控制的断路器轴孔零件装配算法

针对双臂机器人断路器轴孔零件装配操作任务,研究了一种两阶段轴孔装配轨迹规划策略,为了提高双臂协调装配作业的柔顺性和精确性,提出一种FAIC控制算法,实现精确的力跟踪。首先建立轴和孔接触状态力学模型,开展轴孔装配机理研究,根据双臂末端受力平衡,提出了一种操作空间轴孔装配的双臂运动轨迹规划方法。基于阻抗控制实现柔顺轴孔装配,采用模糊控制器在线辨识阻抗控制最优参数,提高装配操作质量。实验结果表明,在双臂协作轴孔装配策略结合FAIC算法作用下,轴孔间接触力控制在3 N以内,装配效率提高36.5%。综上所述,本文提出的FAIC算法与装配策略在双臂协同断路器装配作业中有效地缩短磁组件的装配时间,提高装配效率与精度。

底部钻具组合力学性能分析及优化

深井段复杂地层倾角大,井斜控制难度大,严重影响了安全钻进。为准确控制井眼轨迹,提高钻具的造斜能力,采用纵横弯曲梁法建立力学计算模型,分析井眼曲率、地层倾角、各跨长度和外径、柔性短节、稳定器外径、翼肋推力、钻压和井斜角等因素对多种底部钻具组合力学性能的影响,优化底部钻具组合。研究结果表明:弯螺杆相比于直螺杆有更好的防斜纠斜能力,更适合在深部造斜力强的地层使用;当方位角在25°与205°时地层侧向力最小;定向井段井眼曲率对2种螺杆钻具组合的导向力影响最大,井斜角次之,钻压影响较小;翼肋推力对弯螺杆推靠式旋转导向钻具组合(RSBHA)的造斜力和造斜性能影响最为显著,钻压次之,井斜角的影响较小。研究结果可为复杂地层井斜规律的研究和控制提供参考依据,钻井工具的合理组合及优化对减少井斜问题、顺利完钻起着重要作用。

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。

基于视觉阻抗控制的并联机械臂锥孔装配

针对当前协作机器人在锥孔装配中依赖准确工件位置信息的局限性问题,提出了一种基于视觉阻抗控制的并联机械臂控制方法。首先,根据机器人锥孔装配的原理建立其动力模型,采用针孔模型建立图像特征点的运动模型;然后,基于所构建的动力模型,设计了基于视觉伺服控制和阻抗控制的机械臂混合控制策略,通过末端搭载的视觉系统获取的工件之间的特征点误差以实现机械臂末端的位置和力控制,从而完成工件之间的装配动作;最后,建立了机械臂系统实验平台,进行了工件装配的位置跟踪和末端接触力实验,并将其与传统的力位控制方法进行了对比实验,结果验证了该控制方法的有效性和稳定性。

C/C复合材料超声辅助磨削孔加工质量控制研究

为提高C/C复合材料孔加工出口边缘表面质量,以孔出口损伤因子S_(d)值(孔出口端面损伤面积与加工后理想孔面积之比)作为孔出口质量评价指标,利用单因素及正交试验方法优化磨削工艺参数,分析孔出口边缘磨削机理并提出孔出口损伤抑制策略。结果表明,当主轴转速为12000~14000 r/min,进给速度为5~7 mm/min,超声波振幅为8~9μm时,可将S_(d)值控制在4.723×10^(-3)以内。采用孔损伤抑制策略后,S_(d)值可进一步降低61.6%。此外,C/C复合材料在超声辅助磨削加工下的S_(d)值随主轴转速和超声波振幅的增加先减小后增大,随进给速度的增加逐渐增大;在保证进给速度最优时,适当提高主轴转速及超声波振幅有助于改善孔出口表面质量,并可提高加工效率。采用在临近孔出口时降低进给速度、使用刀具侧壁对孔出口进行光磨及在工件下方加设辅助支撑的策略可进一步降低孔出口损伤。

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。

基于深度强化学习的机器人轴孔装配策略仿真研究

针对现有轴孔装配方法存在的依赖于精确的接触状态模型、数据采集困难、采样效率低、安全性差等问题,提出了一种基于DRL的机器人轴孔装配策略仿真研究方法。搭建了基于ROSGazebo机器人轴孔装配仿真环境,提出了基于最小二乘法对力/力矩传感器进行重力补偿的方法;基于RL的范式对轴孔装配问题建模,并提出了一种基于SAC(soft actor-critic)算法的机器人轴孔装配方法;通过ROS建立了仿真环境与深度强化学习算法的通信机制。实验结果表明:该算法能够使机器人自主且柔顺地完成轴孔装配任务,并具有较好的泛化性。

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.