Unilateral self-locking mechanism for inchworm in-pipe robot

A unilateral self-locking mechanism(USM) was proposed to increase the tractive ability of the inchworm in-pipe robots for pipeline inspection.The USM was basically composed of a cam,a torsional spring and an axis.The self-locking and virtual work principles were applied to studying the basic self-locking condition of the USM.In order to make the cooperation between the crutch and telescopic mechanism more harmonical,the unlocking time of the USM was calculated.A set of parameters were selected to build a virtual model and fabricate a prototype.Both the simulation and performance experiments were carried out in a pipe with a nominal inside diameter of 160 mm.The results show that USM enables the robot to move quickly in one way,and in the other way it helps the robot get self-locking with the pipe wall.The traction of the inchworm robot can rise to 1.2 kN,beyond the limitation of friction of 0.497 kN.

Outcomes of cervical degenerative disc disease treated by anterior cervical discectomy and fusion with self-locking fusion cage

BACKGROUND Cervical degenerative disc(CDD)disease is a common type of spondylosis.Although anterior cervical discectomy and fusion(ACDF)is the preferred treatment for CDD disease,internal fixation with a titanium plate may cause various complications.The invention of the ACDF with a self-locking fusion cage(ROI-C)has effectively decreased the incidence of postoperative complications.AIM To observe the outcomes of CDD disease treated by ACDF with a ROI-C.METHODS Ninety patients with CDD disease treated at our hospital from March 2019 to March 2021 were included.They were divided into two groups(control group and observation group,n=45 in each)using a random number table.Patients in the control group received ACDF plus internal fixation with a titanium plate.Those in the observation group received ACDF+ROI-C placement.The two groups of patients were compared in terms of surgical parameters,pain,cervical spine function,range of motion,and complications.RESULTS The two groups of patients showed no significant differences in surgical time,blood loss,drainage volume,and length of hospital stay(P>0.05).No significant differences in the visual analogue scale(VAS),Japanese Orthopedic Association(JOA),and neck disability index(NDI)scores were observed between the two groups before surgery(P>0.05).The VAS and NDI scores in the observation group were considerably lower than those in the control group after surgery;however,the JOA scores in the observation group were significantly higher than those in the control group(P<0.05).No significant differences were observed in cervical disc height and the range of motion of the superior or inferior adjacent vertebrae between the two groups before surgery(P>0.05).The disc height in the observation group was larger than that in the control group after surgery.The range of motion of both the superior and inferior adjacent vertebrae was significantly smaller in the observation group than in the control group(P<0.05).The incidence of complications was only 2.22% in the observation group compared to 15.56% in the control group,and the difference was statistically significant(P<0.05).CONCLUSION Cervical spine function restoration was better with ROI-C with internal fixation in ACDF than with conventional titanium plates in ACDF for CDD disease.

A self-locking mechanism of the frog-legged beetle Sagra femorata

Insect legs play a crucial role in various modes of locomotion,including walking,jumping,swimming,and other forms of movement.The flexibility of their leg joints is critical in enabling various modes of locomotion.The frog-legged leaf beetle Sagra femorata possesses remarkably enlarged hind legs,which are considered to be a critical adaptation that enables the species to withstand external pressures.When confronted with external threats,S.femorata initiates a stress response by rapidly rotating its hind legs backward and upward to a specific angle,thereby potentially intimidating potential assailants.Based on video analysis,we identified 4 distinct phases of the hind leg rotation process in S.femorata,which were determined by the range of rotation angles(0°−168.77°).Utilizing micro-computed tomography(micro-CT)technology,we performed a 3-dimensional(3D)reconstruction and conducted relative positioning and volumetric analysis of the metacoxa and metatrochanter of S.femorata.Our analysis revealed that the metacoxa–trochanter joint is a“screw-nut”structure connected by 4 muscles,which regulate the rotation of the legs.Further testing using a 3D-printed model of the metacoxa–trochanter joint demonstrated its possession of a self-locking mechanism capable of securing the legs in specific positions to prevent excessive rotation and dislocation.It can be envisioned that this self-locking mechanism holds potential for application in bio-inspired robotics.

颈前路减压融合ROI-C^(TM)自锁系统治疗退行性颈椎病的Meta分析

目的:颈前路减压融合术是治疗退行性颈椎病的经典手术方式,钉板的使用增加了融合率及稳定性的同时,间接导致了邻近椎体退变和术后吞咽困难的发生。文章通过Meta分析方法比较ROI-C^(TM)自锁系统和传统融合器联合钉板内固定治疗退行性颈椎病患者的临床结果和并发症情况,为颈前路减压融合术中内固定方式的选择提供循证学支持。方法:检索中国知网、万方、维普、PubMed、Cochrane Library、Web of Science和Embase数据库,检索关于颈前路减压融合术中应用ROI-C^(TM)自锁系统与融合器联合钉板内固定治疗退行性颈椎病的中英文文献。检索时间范围为各数据库建库至2023年7月。由2名研究者严格按照纳入与排除标准选择文献,采用Cochrane偏倚风险工具对随机对照试验进行质量评价,NOS量表对队列研究进行质量评价。采用RevMan 5.4软件进行Meta分析。结局指标包括手术时间、术中出血量、日本骨科协会(Japanese Orthopaedic Association Scores,JOA)评分、颈椎功能障碍指数、C_(2)-C_(7)Cobb角、融合率、邻近椎体退变发生率、融合器沉降率和吞咽困难发生率。结果:共纳入13项研究,其中回顾性队列研究11项,随机对照试验2项,共1136例患者,ROI-C组569例,融合器联合钉板组567例。Meta分析结果显示:ROI-C组与融合器联合钉板组在手术时间(MD=-15.52,95%CI:-18.62至-12.42,P<0.00001),术中出血量(MD=-24.53,95%CI:-32.46至-16.61,P<0.00001),术后邻近节段退变率(RR=0.40,95%CI:0.27-0.60,P<0.00001)和术后总吞咽困难发生率(RR=0.18,95%CI:0.13-0.26,P<0.00001)均具有显著性差异。两者在术后JOA评分、颈椎功能障碍指数、C_(2)-C_(7)Cobb角、融合率和融合器沉降率方面无显著性差异(P≥0.05)。结论:在颈椎前路减压融合术中应用ROI-C^(TM)自锁系统与传统融合器联合钉板内固定治疗退行性颈椎病均可达到满意的临床效果,ROI-C^(TM)自锁系统操作更加简单,相比融合器联合钉板内固定能明显减少手术时间及术中出血量,在减少术后吞咽困难及邻近节段退变发生率等方面具有明显优势,对于跳跃型颈椎病及邻椎病翻修患者,更加推荐使用ROI-C^(TM)自锁系统。但鉴于其可能存在较高的沉降率,对于多节段且合并融合器沉降高危因素如骨质疏松、椎体终板破损的退行性颈椎病患者,仍建议使用融合器联合钉板内固定。

Rotary self-locking intramedullary nail for long tubular bone fractures

Background Intramedullary nails had been widely used in the treatment of long-bone fractures because of less interference of fractures and center bearing biomechanical advantage. However, it had been also found many shortcomings such as broken nails, delayed healing and was modified in order to achieve better efficacy and reduce complications. The aim of the present study is to compare the efficacy of rotary self-locking intramedullary nails （RSIN） with that of interlocking intramedullary nails （IIN） in the treatment of long-bone fractures.

Self-locked orthogonal polarized dual comb in a microresonator

Dual combs are an emerging tool to obtain unprecedented resolution, high sensitivity, ultrahigh accuracy, broad bandwidth, and ultrafast data updating rate in the fields of molecular spectroscopy, optical metrology, as well as optical frequency synthesis. The recent progress in chip-based microcombs has promoted the on-chip dual-comb measuring systems to a new phase attributed to the large frequency spacing and broad spectrum. In this paper, we demonstrate proof-of-concept dual-comb generation with orthogonal polarization in a single microresonator through pumping both the transverse-electric （TE） and transverse-magnetic （TM） modes simultaneously. The two orthogonal polarized pumps are serf-oscillating in a fiber ring cavity. The generated dual comb exhibits excellent stability due to the intrinsic feedback mechanism of the sdf-locked scheme. The repetition rate of the two orthogonal combs is slightly different because of the mode spacing difference between the TE and TM modes. Such orthogonal polarized dual-combs could be a new comb source for out-of-lab applications in the fields of integrated spectroscopy, ranging measurement, optical frequency synthesis, and microwave comb generation.

A novel anatomical self-locking plate fixation for both-column acetabular fractures

Purpose:To compare the stability of the posterior anatomic self-locking plate(PASP)with two types of popular reconstruction plate fixation,i.e.double reconstruction plate(DRP)and cross reconstruction plate(CRP),and to explore the influence of sitting and turning right/left on implants.Methods:PASP,DRP and CRP were assembled on a finite element model of both-column fractures of the left acetabulum.A load of 600 N and a torque of 8 N·m were loaded on the S1 vertebral body to detect the change of stress and displacement when sitting and turning right/left.Results:The peak stress and displacement of the three kinds of fixation methods under all loading conditions were CRP>DRP>PASP.The peak stress and displacement of PASP are 313.5 MPa and 1.15 mm respectively when turning right;and the minimal was 234.0 Mpa and 0.619 mm when turning left.Conclusion:PASP can provide higher stability than DRP and CRP for both-column acetabular fractures.The rational movement after posterior DRP and PASP fixation for acetabular fracture is to turn to the ipsilateral side,which can avoid implant failure.

Theoretical investigation on the energy absorption of ellipse-shaped self-locked tubes

Self-locked energy-absorbing systems have been proposed in previous studies to overcome the limitations associated with the round-tube systems because they can prevent the lateral splash of tubes from impact loadings without any constraints.In case of self-locked systems,the ellipse-shaped self-locked tube is considered to be an optimal design when compared with the ordinary circle-shaped self-locked tubes and other shaped self-locked tubes.In this study,we aim to theoretically analyze the ellipseshaped self-locked tubes.Further,a plastic hinge model is developed to predict the force-displacement relation of the tube,which is compared with the deformation process observed in the experiment and finite element method(FEM)simulation.Using this model,the effects of tuning the geometric parameters of the tube on the energy absorption performance,including the deformation efficiency,energy absorption capacity,and effective stroke ratio,are simulated and analyzed.Finally,a guideline is provided with respect to the design of the ellipse-shaped self-locked tube in engineering applications.

钢结构模块新型自锁-可解锁式连接节点的抗拉研究

为提高建筑用钢结构模块的施工效率、实现模块单元的快捷装配与拆卸,提出一种新型自锁-可解锁式连接节点方法,用Abaqus数值模拟软件建立了节点的精细化与半精细化有限元模型,探究了摩擦因数对节点抗拉承载性能的影响。选取上限位板厚度、下限位板厚度和上部滑块宽度为关键参数进行有限元模拟,研究各参数对节点抗拉承载力及破坏模式的影响。最后与实际节点抗拉承载力进行对比。结果表明:当摩擦因数为0.3时,新型节点承受最大拉力为1345.49 kN,较角件旋转式连接节点提升约为152%。节点抗拉承载力受上部滑块宽度影响较大,受上限位板厚度与下限位板厚度影响相对小。当上、下限位板厚度均为25mm时,在10~12mm内增加上部滑块宽度可提升节点承载拉力。

预应力CFRP布加固混凝土梁受弯试验

目的 研究不同加固方法下预应力碳纤维布加固混凝土梁的受弯性能,解决桥梁加固缺陷的问题。方法 制作了5根试验梁,其中一根为对比梁,不做任何加固处理,其余4根分别采用不同的锚固方式、不同的初始张拉力及不同的加固位置进行加固,通过控制变量,进行加载试验,分析其受弯性能的差异。结果 经加固后的试验梁承载能力与刚度明显增加,与对比梁相比,极限荷载分别提升了25%、22.06%、30.78%及36.76%;各试验梁达到屈服荷载时,经加固的试验梁挠度均小于对比梁产生的挠度,且模腔自锁式锚具锚固的试验梁挠度小于穿孔式自锁锚具锚固的试验梁挠度,相同锚固方法下初始张拉力较大的试验梁挠度要小于初始张拉力较小的试验梁挠度。结论 使用预应力碳纤维布加固混凝土梁能够有效提高混凝土梁的抗弯性能,提升效果与加固位置、锚固方式及初始张拉力大小有关。

液压泵用推力球轴承疲劳剥落原因

某台液压泵推力球轴承发生疲劳剥落现象。采用宏观观察、化学成分分析、金相检验、硬度测试、压印深度测量等方法对轴承剥落的原因进行分析。结果表明:轴承发生疲劳剥落的原因为,保持架兜孔压印部位变形量大,钢球受到过度约束,钢球与保持架发生运动干涉,最终导致轴承疲劳剥落。采用聚醚醚酮材料制造的自锁保持架替代铜实体保持架,可有效改善推力球轴承疲劳剥落的问题。

指尖自锁欠驱动机械手设计与研究

欠驱动机械手结构简单、成本低、易于控制、自适应能力强,但欠驱动机械手是通过机械限位与弹簧约束来完成抓取,抓取稳定性差,无法输出较大的指尖抓取力.本文提出一种新型的指尖可自锁的欠驱动三指机械手,在抓取时远指节与中指节可实现自锁,增加了抓取的稳定性.同时建立了单指的D-H运动学模型,利用MATLAB分析了机械手的工作空间,对手指进行了静力学分析,利用ADAMS软件对机械手进行仿真分析,最后进行抓取测试,结果表明指尖自锁机械手能输出更大抓取力,从而验证了指尖自锁机械手结构的合理性与可行性.

基于低场核磁共振技术的致密砂岩气藏防水锁作用机理研究

致密砂岩气藏孔隙度、渗透率较低,微观孔喉尺度细小,在生产及压裂过程中极易产生水锁伤害。为开展致密储层防水锁作用机理研究,将常规岩心自吸实验、防水锁剂抑制水锁伤害实验与低场核磁共振技术(nuclear magnetic resonance,NMR)相结合,从微观角度揭示致密砂岩储层微纳米级孔喉中的防水锁作用机理,为致密砂岩气藏防水锁相关研究提供理论依据。结果表明:加入防水锁添加剂后,流体表面张力下降,接触角增大,自吸速率变慢,渗透率有一定程度恢复;在此基础上,通过核磁共振T 2谱从微观角度评价缓慢自吸阶段液体在不同孔喉尺度范围内的液相水锁滞留现象,其中加入防水锁添加剂后在自吸20 h时在较小孔喉处自吸液相平均占比为38.61%,整体孔喉平均液相占比为35.79%。而在未加入防水锁试剂的样品中在自吸20 h时在较小孔喉处液相占比为67.48%,整体孔喉占比为54.52%;通过防水锁剂抑制水锁伤害实验得出,加入防水锁剂后渗透率恢复程度在15.38%~20.19%,整体液相滞留占比平均下降幅度在10.73%。防水锁剂有效地降低较小孔候处液相滞留占比,降低流体表面张力以及增大岩心疏水性能,揭示了致密砂岩气藏防水锁作用机理,为致密砂岩气藏降低水锁伤害程度、提高返排效率,为实现高效开发提供理论支撑。

水合物开采喷射破碎工具自锁式压控机理

喷射破碎工具是天然气水合物开采中用于水合物矿体储层破碎造腔的关键工具。本文旨在解决现有类似工具存在的喷头开关状态不可控、井眼钻进与破碎扩径作业不可自动切换等问题。首先,设计了一种带自锁式压控滑芯的喷射破碎工具,可以通过控制滑芯入口钻井液流量来改变滑芯的位置,实现喷头的开启与关闭及滑芯的自锁与解锁;其次,采用数值模拟方法研究了结构尺寸对滑芯内部压降及轴向力的影响,得到了滑芯内部的最优结构参数。最后,加工了实验样机,实验验证工具的工作性能。研究结果表明:当滑芯入口直径为45 mm、入口角度为30°、出口与直管段直径为30 mm、入口流量为470 L/min时,效果最佳;在常规井眼钻进流量下,喷头不会开启;当入口流量为453 L/min时,喷头完全开启且滑芯实现自锁;当入口流量为253 L/min时,滑芯实现解锁且喷头逐渐关闭;工具自锁流量与设计流量(470 L/min)的最大相对误差为3.62%,在可被认同的误差范围内。因此,在所设计的钻井液流量下,自锁式压控滑芯喷射破碎工具的射流喷头可以正常开启与关闭,滑芯能完成自锁与解锁。

双叉戟状空间自锁吸能系统设计及吸能性能研究

自锁吸能系统可无需外加约束而避免元件在冲击荷载下的横向飞溅,具有广阔的应用前景。然而,已有自锁吸能系统大都只在特定方向具有自锁稳定性,构型复杂且造价昂贵,或截面形状特殊,不便拆装,制约了应用和推广。为此,该文提出了一种新型的多向自锁能量吸收系统,由具有双叉戟状横截面的薄壁管组成,拆装方式灵活便捷。当系统受冲击时,管件的管槽限制了相邻主体管的位移,使管件系统在空间多个方向的冲击载荷下,均可实现自锁,并且充分变形,稳定吸能。通过有限元分析,系统考察了双叉戟单管的几何参数效应以及阵列轮廓尺寸对系统吸能特性的影响。相较于已有的自锁系统,该文发展的双叉戟自锁吸能系统具有更优异的吸能特性。

无托槽隐形矫治器与金属自锁矫治器对成人正畸患者牙周健康的影响

目的 对比无托槽隐形矫治器和金属自锁托槽矫治器对成人正畸患者牙周健康的影响。方法 选取2019至2022年就诊的正畸患者200例,根据矫治方法可分为无托槽隐形矫治器组(隐形组)和金属自锁托槽矫治器组(托槽组),每组100例。比较2组患者正畸前后不同时间点的菌斑指数(plaque index, PI)、牙龈指数(gingival index, GI)、龈沟出血指数(SBI)和探诊深度(PD),检测患者正畸前后龈沟液中天冬氨酸转氨酶(AST)、碱性磷酸酶(ALP)、白介素1β(IL-1β)、白介素6(IL-6)、肿瘤坏死因子-α(TNF-α)和细胞核因子κB受体活化子配体(RANKL)的表达。结果 2组患者矫正后的PI、GI和SBI均高于矫正前,但隐形组的各项指数明显更低(P<0.05)。2组患者矫正前后不同时间点PD比较,差异无统计学意义(P>0.05)。2组患者矫治后的AST、ALP、IL-1β、IL-6、TNF-α和RANKL表达均明显升高(P<0.05),且隐形组显著低于托槽组(P<0.05)。结论 虽然两种矫治器均对患者的牙周健康产生不良影响,但无托槽隐形矫治后患者的牙周健康指数明显更优,龈沟液中酶及炎性因子的表达明显更少,无托槽隐形器更利于维护患者的牙周健康。

可调谐脉宽的全固态自锁模突发脉冲激光器

针对目前脉冲激光器产生突发脉冲功率低、装置复杂等问题,设计一种可调谐脉宽的全固态自锁模突发脉冲激光器,理论分析了腔内法布里-珀罗(F-P)结构的自锁模激光器的突发脉冲产生机理,建立了自锁模突发脉冲激光器的理论模型。实验结果表明:随着激光晶体长度的增加,突发脉冲的脉宽变宽;当激光晶体长度为5 mm、泵浦光功率为5.5 W时,获得了光束质量因子为1.42的突发脉冲,突发脉冲的重复频率为13.64 GHz,最大平均输出功率0.78 W,对应的斜效率和光光转化率分别为9.57%和8.73%。

可调谐腔长的Nd:YVO_(4)自锁模激光器

针对自锁模激光器中标准具效应影响激光输出性能的问题,设计了一种可调谐腔长的Nd:YVO_(4)自锁模激光器。利用单端镀膜的晶体构成腔内标准具,对激光进行选模。理论上分析了不同腔长下光谱的模式分布与其对应的时序图,实验验证了Nd:YVO_(4)晶体的荧光谱温度特性,并分别分析了其激光光谱特性、锁模脉冲序列的时间轨迹以及频谱分布。理论与仿真结果表明:当标准具的厚度与谐振腔长的光学长度之比为b/q的简分数时,纵向模式间距可被修改为原来的q倍,并输出q次谐波锁模激光;当腔长为12.2 mm,调整标准具厚度与谐振腔长的光学长度之比为3/5时,获得了41.4 GHz的高重复频率脉冲激光输出;当垂直方向半管为6 578 m W时,平均输出功率超过2.0 W,对应的斜效率和光对光转化率分别为31.2%和30.7%。

基于传动比法3K(Ⅲ)型行星轮系自锁及效率最大化研究

行星轮系结构紧凑、传动效率高,在工业制造领域中运用广泛;对于具有自锁特性的机构,行星轮系存在广阔的运用空间。基于传动比法分析了3K(Ⅲ)型行星轮系的功率流向及效率公式,通过对该种行星轮系自锁时的效率进行优化处理,改善其运行性能,从而得到提高传动效率后的行星齿轮组反向自锁的传动比设置以及相应的效率大小。首先,利用基本公式求解周转轮系的传动比;其次,针对不同的情况分析周转轮系的功率流向;然后,综合上述条件绘制出效率曲线,并结合实例分析轮系自锁时的传动比状况;最后,通过具体案例验证了该方案的准确性和有效性。该方法能够得出存在反向自锁现象、行星轮系效率最大化时的传动比参数。

船用楔形齿桨轴离合器设计与仿真分析

针对船用楔形齿桨轴离合器的参数设计问题,开展了船用楔形齿桨轴离合器设计研究。理论分析了船用楔形齿桨轴离合器自锁所需的临界摩擦因数随楔形齿压力角和楔形角变化的规律,并进行了仿真验证;建立了船用楔形齿桨轴离合器的多体动力学模型,研究了存在对齿误差时的接合过程。结果表明,船用楔形齿桨轴离合器降低了对齿过程的精度需求,在接合对齿过程存在0.4°以内的误差时可以在自身导向作用下完成接合。推导的自锁临界摩擦因数公式可以用来指导船用楔形齿桨轴离合器设计。