Crack-free high-aspect ratio holes in glasses by top–down percussion drilling with infrared femtosecond laser GHz-bursts

We report novel results on top-down percussion drilling in different glasses with femtosecond laser GHz-bursts.Thanks to this particular regime of light–matter interaction,combining non-linear absorption and thermal cumulative effects,we obtained crack-free holes of aspect ratios exceeding 30 in sodalime and 70 in fused silica.The results are discussed in terms of inner wall morphology,aspect ratio and drilling speed.

Capacitor discharge percussion welding of pure aluminum wire to pure copper sheet

This paper presents the results of a research into capacitor discharge percussion welding （CDPW） of pure aluminum wires and pure copper sheets, using percussion welding power and special welding device. A lot of CDPW factors, which will affect aluminum and copper dissimilar bonding, are described and these parameters have also been optimized. The fracture pull, interface compounds, microstructure and hardness are all studied. The results show that aluminum wire welding to copper sheet can form a sound weld and in some conditions the fracture pull is similar to that of the pure aluminum wires. The capacitance, discharge voltage, wire taper angle and machine oil as welding assistant medium affect fracture pull. The intermetaUic compounds A12 Cu appears on the copper side of joint. Narrower heat-affected zone is observed.

Stability of rat models of fluid percussion-induced traumatic brain injury: comparison of three different impact forces

Fluid percussion-induced traumatic brain injury models have been widely used in experimental research for years. In an experiment, the stability of impaction is inevitably affected by factors such as the appearance of liquid spikes. Management of impact pressure is a crucial factor that determines the stability of these models, and direction of impact control is another basic element. To improve experimental stability, we calculated a pressure curve by generating repeated impacts using a fluid percussion device at different pendulum angles. A stereotactic frame was used to control the direction of impact. We produced stable and reproducible models, including mild, moderate, and severe traumatic brain injury, using the MODEL01-B device at pendulum angles of 6°, 11° and 13°, with corresponding impact force values of 1.0 ± 0.11 atm（101.32 ± 11.16 k Pa）, 2.6 ± 0.16 atm（263.44 ± 16.21 k Pa）, and 3.6 ± 0.16 atm（364.77 ± 16.21 k Pa）, respectively. Behavioral tests, hematoxylin-eosin staining, and magnetic resonance imaging revealed that models for different degrees of injury were consistent with the clinical properties of mild, moderate, and severe craniocerebral injuries. Using this method, we established fluid percussion models for different degrees of injury and stabilized pathological features based on precise power and direction control.

KANE’S EQUATIONS FOR PERCUSSION MOTION OF VARIABLE MASS NONHOLONOMIC MECHANICAL SYSTEMS

In this paper,the Kane’s equations for the Routh’s form of variable massnonholonomic systems are established.and the Kane’s equations for percussion motionof variable mass holonomic and nonholonomic systems are deduced from them. Secondly,the equivalence to Lagrange’s equations for percussion motion and Kane’sequations is obtained,and the application of the new equation is illustrated by anexample.

THREE DIMENSIONAL DYNAMIC ELASTICPLASTIC ANALYSIS OF THE INTERACTION OF A SET OF PERCUSSION BITS WITH ROCK MASSES

A three dimensional dynamic elastic-plastic finite element analysis of the interaction of percussion bits with rock masses is presented. The dynamic contact problem was investigated with the numerical method developed for high velocity impact calculations[1]. The numerical analysis was carried out for three simultaneously loaded percussion bits arranged on a straight line on the rock surface, the loading time was kept constant throughout this work. The numerical calculation for various strengths of the dynamic load tm the percussion bits shows that a critical minimum dynamic load exists for the generation of plastic deformations in the rock. For this critical value of the load the maximum normal stress of the longitudinal wave in the percussion bit exceeds the yield stress of the rock mass.

Study on the Mechanism of Fluid Percussion Injuries on Immune Cells

Background Traffic accidents,anti-terrorism,gas and chemical dangerous goods explosions,earthquake shock wave damage,and falling impacts in daily life and other events involving impact loads cause great harm to human organs and tissues,and even life-threatening.Such injuries are called impact damage.Although during the previous wars,the treatment of impact injuries has been greatly improved,and its treatment has been widely used in clinical practice.However,under the current development of society,the impact damage incident has not only been limited to the battlefield.Extreme organizations,frequent industrial production accidents,aircraft trains and other accidents have extended the impact damage incidents into daily society,seriously jeopardizing the health of civilians.Therefore,in order to better treat the injured organs under the impact load,such as the reconstruction and recovery of organ tissues,it is necessary to establish a corresponding system of clinical treatment methods for impact damage.In vitro models of traumatic injury are helping elucidate the pathobiological mechanisms responsible for dysfunction and delayed cell functional variation after mechanical stimulation of the single waveform pressure.It is likely that injury outcome is related to the biomechanical parameters of the traumatic event such as amplitudes and durations.However,the influence of impulsive pressure on endothelial function has not yet been fully studied in vitro.In this study,we developed a pressure loading device that produced positive by modifying an in vitro fluid percussion model and examined the effects of the pressures on macrophages’basic functions.Methods To model variations in the biomechanical injury parameters and simplify the experiment,single-use syringe was chosen to be the cell container and a drop hammer driven fluid percussion injury system(FPI)was designed and built to generate a single waveform with adjustable peak pressure and durations.Mice macrophage cells(Raw 264.7)were subjected to three types of the single positive pressure(120 kPa,550 kPa and 1 100 kPa).Every 12 hours we detected its basic functions(including phagocytosis and proliferative capacity)during the following 48 hours,also the immediate cell death.Results This single waveform pressure loading device could produce positive pressure with amplitudes of 70~1 200 kPa.After the pressure loading,there is no significant differences between the control cells and experiment cells.However,it does have a notable effect on its basic functions.The results showed that its phagocytosis and proliferative capacity were getting increased with a peak value on36 h and suddenly decreasing on 48 h.Moreover,these 4 regular curves are in proportion to the pressure.And the experimental results also indicate that the cell impact platform can achieve a single impact loading on the cells.The impact mainly causes the functional changes of RAW264.7 cells instead of directly causing its death.The cell proliferation activity and phagocytosis function are enhanced to some extent.Conclusions Those results indicate that single waveform pressure have a main effect on cell’s biological functions,not on cell death.And these effects on functions did have a regular functional rela-tionship.To explore more regular curves and the mechanism,we need more experiments such as genomics technical.

Effects of Latin,Rock and African Percussion Music on Protein and Energy Metabolism in Cow

This study was conducted to study the effects of Latin,rock,and African percussion music on milk production performance in cow. 72 Holstein cows with similar milk yield,age,parity and lactation were randomly divided into four groups,namely the Latin music group,rock music group,African percussion music group and control group,each 18 cows. The pretrial period lasted for 7 d,and the formal trial period was 60 d. The music began to be played in test group from pretrial period,while the control group received routine feeding. Milk yield was measured every 20 d,and milk sample was collected once. The results showed that African percussion music could increase the contents of GLB,ALT and LDH in the serum of cow,and reduce the milk yield of cow. Rock music would increase the serum LDH content in cow and reduce the milk yield of cow.

Acoustic Performance of Green Composites for Chinese Traditional Percussion Drums

Flax and jute fabrics are adopted to reinforce epoxy matrix composites in order to explore the feasibility of replacing wood in percussion instruments.The fabrics are treated with alkaline solutions to improve interfacial adhesion between fibers and epoxy.The composites are fabricated using the hand-lay and vacuum assisted resin infusion process.Acoustic dynamic moduli,acoustic radiation damping coefficients,and acoustic impedances of the composites are tested and compared with those of the wood regularly used to make the percussion instruments.It is found that the acoustic properties of the composites are within the range of those of the wood,indicating that it could be feasible to replace the wood with natural cellulose fiber reinforced composites in percussion instrument production.

New Properties of HM16 Ether, with Submicroparticles as Self-Functional Cells Interacting through Percussion Forces, Establishing Nature of Electrical Charges, including Gravitation

Article continues and complements our previous articles on the HM16 ether (ETH) model. Here, we describe the mechanism of occurrence of the submicroparticle (SMP). A general hypothesis, HFVI, is introduced for the modalities of interaction between two SMPs, based on periodic mechanical percussion forces, produced by fundamental vibrations FVs. A mechanism for describing the interaction between a SMPs and the ETH is presented. Positive and negative particles are defined by their membrane types of movement, such as +, −u/+, −v vibrations, and rotations at speeds +Ω/−Ω. The process of creating a pair of SMPs is discussed. Applying HFVI to the interaction between pairs of SMPs immobile in ETH, and considering longitudinal FVL, was obtained the forces of attraction/repulsion +FL21/–FL21, which correspond to the completed Coulomb force FCC including gravitation. The resultant FRL21 will form an oriented field of forces, which is a quasielectric field QE, equivalent to actual E electric field. Considering transversal FVT, was obtained the vibratory forces +, −FT21, whose resultant forms an vibrating field of forces, QHs, a quasimagnetic special field, which may explain some of the quantum properties of SMPs. Considering a mobile SMP, two new γ strains in ETH appear. Strains γL are created by the displacement of SMP with velocity V, whose force +, −FT12 is the support of a component of the magnetic field H (quasimagnetic field QH), giving the QHL component. Strains γR are created by the rotation of SMP with speed Ω, whose force +, −FR12 constitutes physical support of the component QHR of magnetic field H (i.e. QH). The creation of a photon PH is modelled as a special ESMP containing two zones of opposed rotations, and a mechanism is presented for its movement in the ETH with speed c based on the HS hypothesis of screwing in ETH, with frequency ν.

Micro-macro fracture mechanism of heterogeneous granite in percussive drilling

The conventional rotary rock breaking method faces a technical bottleneck in improving the rate of penetration(ROP)in deep hard formations.Percussive drilling is the most potential approach to increase rock-breaking efficiency and ROP.However,the rock-breaking mechanism of percussive drilling is still unclear enough,especially the micro-fracture mechanism of rock under confining pressure(under lateral pressure and hydraulic pressure).In this paper,the impact rock breaking experiments by four kinds of Polycrystalline Diamond Compact(PDC)cutters are carried out using a drop-weight impact testing machine and an acoustic emission(AE)recording system,the influence of parameters such as cutter shape,rake angle,and impact energy on rock-breaking are systematically analyzed.This study includes a numerical simulation to examine the process of crack initiation,propagation,and cuttings formation during the impact process with the consideration of confining pressure.The results show the conicalshaped cutter is the most aggressive with high breaking efficiency.The penetration depth of the cutter is mainly influenced by the impact energy and cutter shape than the rake angle of the cutter.There exists critical impact energy makes the rock breaking efficiency the highest.The critical impact energy is about 40 J when using the conical-shaped cutter with a rake angle of 15°.The rock mainly failed in tensile mode,and the inter-grain crack is the main crack.Hydraulic pressure can inhibit the formation of horizontal cracks,while lateral pressure can inhibit the formation of vertical cracks and reduce the proportion of tensile cracks.The research results can provide some reference and basis for improving the rock-breaking efficiency in deep hard formations.

Study on drilling mechanism and optimization of percussion-extruding DTH hammer bit

The authors tested the percussion-extruding Down-the-hole(DTH)hammer bit with five different structures and mainly analyzed the drilling mechanism between conical bit and stepped bit.In addition,aiming at "the pile effect" in combination with the advantage of stepped bit,we design a new cam spinning bit and test it outdoors.The result shows that using cam spinning bit can solve the problem of "the pile effect",which can also obtain higher drilling efficiency than using conical bit in high confining pressure strata.It is characterized by novel structure and high drilling speed as well as good guiding,and it is significant for improving efficiency in percussion-extruding drilling technique.

冲击破岩钻井提速技术研究现状与发展建议

提高钻井速度不仅是提高我国油气效益开发及深地勘探等方面的重要技术手段,同时对保障国家能源安全意义重大。冲击破岩钻井技术在国内外油田现场应用并获得了良好的提速效果,持续开展此类技术攻关有望攻克当下我国深地高温高压硬岩地层进尺低、提速难的技术痛点。介绍和分析了轴向冲击、扭力冲击和轴-扭耦合冲击辅助钻头破岩钻进技术方面的实践及发展动态。结合冲击破岩钻井技术现状,阐明了冲击辅助钻头破岩力学原理是冲击破岩钻井提速技术的关键问题,综述了国内外研究学者在冲击辅助钻头破岩物理实验、理论模型和数值模拟等研究方法上取得的科学进展。针对冲击破岩钻井提速技术的发展提出了相关建议,即加强在材料结构优化设计、智能化控制、多元技术融合和井场应用优化等方面的研究力度,为我国能源高效开发做出贡献。

年轻恒牙外伤性冠折露髓时间与初诊叩痛对预后的影响

目的探讨外伤引起的年轻恒牙冠折露髓患者经活髓切断术或直接盖髓术后预后不良的独立危险因素,并评价露髓时间、初诊叩痛对牙髓预后的影响。方法回顾性分析2018年3月至2020年9月河北省承德医学院附属医院收治的219例外伤引起的年轻恒牙冠折露髓患者的临床资料。患者初诊治疗为活髓切断术或直接盖髓术且于术后1年进行随访。采用单因素和多因素logistic回归分析影响牙髓预后不良的独立危险因素,并通过受试者操作特征(ROC)曲线分析上述独立危险因素对牙髓预后不良的预测价值。结果经术后1年随访,治疗失败20例,成功199例,活髓切断术总成功率为90.87%。单因素分析结果显示,根尖发育情况、露髓时间、初诊叩痛与牙髓预后不良有关(P<0.05),而年龄、性别、受伤原因、受伤牙位、温度试验结果、牙髓电活力差值、露髓孔直径、患牙松动度、治疗方案与牙髓不良预后无关(P>0.05)。多因素logistic回归分析结果显示,初诊叩痛(+++)是影响牙髓预后不良的独立危险因素(P<0.05)。ROC曲线分析结果显示,初诊叩痛(+++)预测牙髓预后不良的曲线下面积为0.860,敏感度为0.832,特异度为0.865。结论初诊叩痛(+++)是外伤引起的年轻恒牙冠折露髓患者预后不良的独立危险因素,且对预后不良的预测价值较高,而露髓时间与牙髓预后无明显相关性。

冲旋步进钻井提速方法的井底裂纹拓展特性

针对深部地层井底岩石硬度高、强度大和应力集中现象导致的岩石可钻性差、破岩效率低和使用寿命短的问题,提出旋冲钻井和差压步进破岩方法相结合的冲旋步进钻井提速新理念。为了研究冲击作用下差压步进钻头破碎地层岩石的裂纹拓展规律,采用有限-离散元(FDEM)方法建立了球齿冲击三维薄板模型,开展了球齿在不同冲击能量、冲击位置及岩石种类等条件下的冲击破岩过程模拟,获得了阶梯型井底岩石在冲击作用下的裂纹扩展规律。研究结果表明:由于阶梯面的存在,球齿在冲击作用下对阶梯型井底造成的预损伤区域比常规井底更大,冲击位置靠近阶梯面的裂纹扩展效果更好;双球齿冲击阶梯井底容易形成较大范围的岩石破碎区,降低了破碎阶梯井底地层岩石的难度;球齿冲击过程中对青砂岩造成的预损伤区域比花岗岩大,在冲击能量相同的情况下球齿冲击破碎花岗岩更为困难。利用冲旋步进钻井方法理论上可以进一步提高难钻地层钻井速度,但具体效果需要经现场试验及优化。所得结论可为深部难钻地层钻井速度的提升提供新的思路。

传统音乐学科的主体性实践与审视——江南区域中的吹打乐种教研叙事

聚焦中国传统音乐理论学科“十番锣鼓研究”路径,结合团队近二十年来的相关研究成果,在教学与科研的学习与反思中、在向民间音乐学习传承与转换中,以乐谱、乐人、乐班、乐器等相关论域的收集整理,作为课题研究的基石,依托江南区域音乐文化重要的土壤和源泉,向民间音乐学习和实地考察,以学术界通用的经典文献史料、民间礼俗及美学观念为背景,将乐种放置于与曲种、剧种、歌种的地缘交互关系之中,结合对流传广泛与影响大的曲牌的活态音乐形态分析,充分展示中国传统音乐自身学科话语体系的主体性存在意义与学术反思。

旋冲钻具凸轮-滚轮冲击机构工作特性分析

旋冲钻具能有效提高深层、硬地层的破岩效率,具有广阔的应用前景。凸轮-滚轮是实现冲击动作的关键机构,但复杂多变的井下环境导致机构损伤严重,进而影响破岩效率。基于旋冲钻具多井次的试钻数据,建立凸轮-滚轮动力学模型,通过显式动力学(Autodyn)分析不同冲程、转速、钻压下的工作特性,总结机构的形变特征提出优化方法。分析结果与试验数据和理论数值对比,验证了计算模型的准确性。结果表明:冲程增大可提高冲击效果,但高于10 mm冲程的滚子实际运动轨迹受钻速、滚轮尺寸、凸轮轮廓曲率影响其轨迹将变平缓。转速在9~18 rad/s时轴向加速度波动幅度较大,对钻具的稳定性具有一定影响。钻压增大凸轮内缘处形变特性明显,其形变量与钻压成正比,25 kN钻压下凸轮的形变量约是10 kN的2.6倍。凸轮齿顶、滚轮内缘处为易变形点,在齿顶处安装可换滚筒同时改变滚轮为鼓轮构型并对抛物线-直线-抛物线、2次多项式、摆线、7次多项式4类凸轮轮廓线型进行特性分析。选用摆线及7次多项式凸轮座轮廓和鼓轮可提高冲击效果,计算结果可为旋冲钻具设计提供参考依据。

旋冲钻进系统控制策略研究现状与发展趋势

深部硬岩地层钻进效率低、成本高等问题是深井、超深井钻井过程中长期面临的难点问题。旋冲钻进技术由于破岩效率高、能降低黏滑振动以及钻压传递效率高等优点,在深地资源勘探开采、应急钻孔救援、钻井工程施工等领域逐渐得到应用,呈现出广阔的应用前景。然而,旋冲钻进系统具有强耦合、高度非线性、参数时变性、负载工况多变、多源动力协同等特性,常规控制方法难以取得理想的控制效果。为提升深井、超深井高端钻进装备的可靠性和智能化水平,研究钻进系统的控制策略具有重要的理论研究价值和工程实际意义。对旋冲钻进系统的组成结构及功能进行介绍;从钻速、钻压、钻进轨迹控制等角度综述近年来国内外研究机构和学者的研究成果;最后,对旋冲钻进系统控制策略未来的发展方向进行分析与展望。

冲击螺杆钻具结构设计与参数优化

为了高效钻进硬岩地层,将螺杆钻具的大扭矩与轴向冲击工具的高频低幅冲击特性相结合,研制了一种冲击螺杆钻具。在工具结构原理讨论的基础上,建立了轴向冲击短节的冲锤运动控制方程,分析了冲锤的运动特性,并以工具冲击功和最大能量利用率为评价指标,采用正交试验方法对主要工具结构参数进行了优化研究。研究结果表明:冲锤往复运动过程为加速度逐渐减小的非线性加速运动,节流喷嘴直径和冲锤运动行程是影响冲击功的主要因素,而冲锤质量、承压面积和腔体通孔面积是次要因素。节流喷嘴直径和冲锤承压面积是影响最大能量利用率的主要因素;而冲锤运动行程、冲锤质量和腔体通孔面积是次要因素。所得结论可为对冲击螺杆钻具的进一步优化设计和现场应用提供参考。

旋冲钻井技术研究现状与展望

随着中国资源勘探开发面向深层、超深层发展以及对应急钻孔救援水平保障能力的更高需求,旋冲钻井技术成为高效钻井领域的研究热点.旋冲钻井技术相较于传统旋转钻井技术,具备硬岩地层钻进效率高、钻压调控灵活、黏滑振动强度低等优势,广泛应用于深海深地资源勘探开采、应急钻孔救援等领域,具有广阔的应用前景.现阶段,在复杂岩层以及多变工况等条件下,进一步提高旋冲钻进效率、降低成本成为深井、超深井钻井过程中面临的首要任务.文中首先介绍了旋冲钻井技术的基本概念及优势;其次,综述了液动和气动2种冲击器的研制情况及结构特点;再次,讨论了高效破岩机制的研究进展和优化策略;从次,阐述了钻进效率关键影响因素方面的研究成果;最后,基于旋冲钻井技术研究成果和面临的挑战,对其未来研究方向进行了分析和展望.

潜孔冲击器钎头合金齿装配过盈量分析

潜孔冲击器钻进效率高成孔质量好广泛应用于各类成孔作业。冲击器工作过程中钎头受到活塞的高频次撞击和地层的反扭矩作用,钎头掉齿是主要失效问题。根据某石灰石矿场钎头的掉齿失效,分析了合金齿掉齿失效机理,基于厚壁圆筒理论、Tresca屈服条件和全增量理论等理论,分析并计算合金齿极限过盈量,确定过盈量合理范围。通过有限元仿真,模拟分析合金齿过盈装配过程。研究表明,过盈量不够导致固齿力小于脱齿力是发生掉齿的主因,通过分析对比理论计算与仿真模拟结果,得到合金齿装配优选过盈量为0.065 mm,能有效防止掉齿、脱齿现象发生。改进的钎头投入使用后,使用寿命较上一代有较大提升,对后续潜孔冲击器的设计与应用有一定的指导意义。