Shear behavior of two-order morphology in rock joints

Two-order morphology of rock joints named as waviness and unevenness can be separated by morphology classification method,which plays a decisive role in the evolution of shear stress during the shear test.The joint morphology is obtained by using 3D printing and 3D laser scanning techniques and the joint model samples in two-order morphology are produced by cement mortar.Then,shear tests are performed under different normal loads.Results shows that the waviness is dominant in the total morphology during the shear test,and the shear contribution of unevenness mainly occurs in the climbing phase of shearing process.Comparing the failure modes of two-order morphology,waviness mainly embodies shear dilation characteristics and unevenness mainly shows shear wear characteristics.Based on this,a quantitative parameter is proposed to represent the ratio of the peak shear strength of the two-order morphology to that of total morphology.The functional relationship between the peak shear strength of total and two-order morphologies is determined,providing a theoretical method for further in-depth study on the shear strength of the interaction with two-order morphology of rock joints.

Measurement on Morphology and Kinematics of Crucian Vertebral Joints

In order to provide data for joints control of our recently designed crucian hke biomlmetlc robot fish, an A-ray photograph technology was adopted to determine the number and length of vertebral joints. A frame-by-frame analysis of high-speed videotapes was conducted to quantify the kinematics of crucian at four speeds （12.651 cm·s^-1, 18.201 cm·s^-1, 21.901 cm·s^-1, 24.368cm·s^-1） during cruising. In addition to a brief introduction to experimental conditions and methods, we analyzed the influence of individual diversity on the absolute length as well as the non-dimensional length of vertebral joints. We also presented the maximal angular velocity and acceleration of vertebral joints under four swimming speeds, and provided the change of relative rotation angle, angular difference, angular velocity and angular acceleration of the rear vertebral joints with time at a certain swimming speed of 12.651 cm·s^-1. At last, we presented the maximal lateral displacement of each mark at that speed. The study found that the influence of individual diversity on the non-dimensional length of vertebral joints is not significant; the maximal angular velocity and acceleration of vertebral joints increase with swimming speed; angular difference, angular velocity and angular acceleration exhibit two maximal values over one period at a certain swimming speed.

Microstructure and fracture morphology of Mo-Cu/Cr18-Ni8 brazed joint in vacuum

Mo-Cu composite and Cr18-Ni8 stainless steel were brazed with Ni-Cr-P filler metal in a vacuum of 10-4 Pa and a Mo-Cu/Cr18-Ni8 joint was obtained. Microstructure in Mo-Cu/Cr18-Ni8 joint was investigated by field-emission scanning electron microscope( FE-SEM) with energy dispersive spectrometer( EDS). Shear strength of Mo-Cu/Cr18-Ni8 lap joint was measured by electromechanical universal testing machine. An excellent Mo-Cu/Cr18-Ni8 joint with a shear strength of 155 MPa was achieved at 980 ℃ for 20 min. Brazed joint was mainly comprised of eutectic structure in the center of brazing seam,matrix structure and lump structure. Ni-Cu( Mo) and Ni-Fe solid solution were at the interface beside Mo-Cu composite and Cr18-Ni8 stainless steel,respectively. Shear fracture exhibited mixed ductile-brittle fracture feature with trans-granular fracture,ductile dimples and tearing edges. Fracture originated from the interface between brazing seam and Mo-Cu composite.

Degradation of joint surface morphology, shear behavior and closure characteristics during cyclic loading

In order to investigate the failure mechanism of rock joint,a series of laboratory tests including cyclic direct shear tests under constant normal load(CNL)conditions were conducted.Morphology parameters of the rock joint surface were precisely calculated by means of a three-dimensional laser scanning machine.All test results were analyzed to investigate the shear behavior and normal displacement behavior of rock joints under CNL conditions.Degradation of rock joint surface during cyclic shear tests was also analyzed.The comparison results of the height parameters and the hybrid parameters of the joint surface during cyclic tests show that the degradation of the surface mostly happens in the first shear and the constant normal loads imposed on the joints have significant promotion effects on the morphology degradation.During cyclic shear tests,joints surfaces evolve from rough state to smooth state but keep an overall undulation.Dilatancy of rock joints degrades with the degradation of joint surface and the increase of normal loads.The closure deformation of joint is larger than that of the intact rock,and the normal stiffness increases with the increase of shearing times.

Morphology characteristics of joint surface in rock mass

In order to quantify the characteristics of the surface of jointed rock mass,new equipment,the three-dimensional laser surface topography instrument,was used to accurately measure surface morphology of joints.Scan pictures and parameters were obtained to describe the rock joint surface characteristics,for example,the height frequency of surface,and mean square roughness.Using the method of fractal dimension,the values of joint roughness coefficient(JRC) were calculated based on the above parameters.It could access to the joint surface rock sample morphology of the main parameters of characteristic.The maximum peak height is 2.692 mm in the test joint plane.The maximum profile height is 4.408 mm.JRC value is 6.38 by fractal dimension computing.It belongs to the smooth joint surface.The results show that it is a kind of the effective method to quantitatively evaluate the surface topography by the three-dimensional laser surface topography instrument and the fractal dimension method.According to the results,during the process of underground large-scale mining,safe measures to prevent slip failure of the joint plane by controlling surface tension and shear mechanical response were proposed.

Usefulness of the acromioclavicular joint cross-sectional area as a diagnostic image parameter of acromioclavicular osteoarthritis

BACKGROUND Acromioclavicular joint(ACJ)space narrowing has been considered to be an important diagnostic image parameter of ACJ osteoarthritis(ACJO).However,the morphology of the ACJ space is irregular because of osteophyte formation,subchondral irregularity,capsular distention,sclerosis,and erosion.Therefore,we created the ACJ cross-sectional area(ACJCSA)as a new diagnostic image parameter to assess the irregular morphologic changes of the ACJ.AIM To hypothesize that the ACJCSA is a new diagnostic image parameter for ACJO.METHODS ACJ samples were obtained from 35 patients with ACJO and 30 healthy individuals who underwent shoulder magnetic resonance(S-MR)imaging that revealed no evidence of ACJO.Oblique coronal,T2-weighted,fat-suppressed SMR images were acquired at the ACJ level from the two groups.We measured the ACJCSA and the ACJ space width(ACJSW)at the ACJ on the S-MR images using our imaging analysis program.The ACJCSA was measured as the cross-sectional area of the ACJ.The ACJSW was measured as the narrowest point between the acromion and the clavicle.RESULTS The average ACJCSA was 39.88±10.60 mm;in the normal group and 18.80±5.13 mm;in the ACJO group.The mean ACJSW was 3.51±0.58 mm in the normal group and 2.02±0.48 mm in the ACJO group.ACJO individuals had significantly lower ACJCSA and ACJSW than the healthy individuals.Receiver operating characteristic curve analyses demonstrated that the most suitable ACJCSA cutoff score was 26.14 mm^(2),with 91.4%sensitivity and 90.0%specificity.CONCLUSION The optimal ACJSW cutoff score was 2.37 mm,with 88.6%sensitivity and 96.7%specificity.Even though both the ACJCSA and ACJSW were significantly associated with ACJO,the ACJCSA was a more sensitive diagnostic image parameter.

Effects of laser heat treatment on the fracture morphologies of X80 pipeline steel welded joints by stress corrosion

The surfaces of X80 pipeline steel welded joints were processed with a CO2 laser, and the effects of laser heat treatment （LHT） on H2S stress corrosion in the National Association of Corrosion Engineers （NACE） solution were analyzed by a slow strain rate test. The fracture morphologies and chemical components of corrosive products before and after LHT were analyzed by scanning electron microscopy and energy-dispersive spectroscopy, respectively, and the mechanism of LHT on stress corrosion cracking was discussed. Results showed that the fracture for welded joints was brittle in its original state, while it was transformed to a ductile fracture after LHT. The tendencies of hydrogen-induced corrosion were reduced, and the stress corrosion sensitivity index decreased from 35.2% to 25.3%, indicating that the stress corrosion resistance of X80 pipeline steel welded joints has been improved by LHT.

Morphological parameters of both surfaces of coupled joint

Twenty one joints were made with Brazilian tests and each surface was scanned by the Talysurf CLI 2000. Morphological characteristics of joint surface were quantified by statistical and textural parameters. By the contrast of these parameters between both sides of each coupled joint, the following conclusions are drawn. The upper and lower surfaces of coupled joints have approximately equal values of Sp（maximum height of joint surface）, Sa（arithmetic mean height of joint surface） and Sq（root mean square height of joint surface）, but the Ssk（skewness of the height distribution of joint surface） values of the two surfaces of a coupled joint are different, one is positive while the other is negative. The Saj（auto-correlation length） parameter values of both surfaces of each coupled joint are quite close, and the S^（texture aspect ratio） values have the same situation to the Sal parameter, but the same parameters of different surfaces have big differences which illustrates its own characteristics of each joint. The two surfaces of each coupled joint have similar values of θp （mean profile angle） which can be used to deduce the value of θp each other.

Morphological and mechanical analysis of natural marble joints submitted to shear tests

In order to evaluate the influence of the surface morphology on the mechanical behavior of twelve natural marble joints, very accurate topography measurements of joint surfaces under constant normal load （CNL） conditions were performed before and after shear tests. The surface topography was carried out using a three-dimensional （3D） laser-scanning profilometer with a parallel grid at a regular interval of 500 gin. Each surface before shearing was reconstructed by geostatistical methods according to eight different directions. A quantitative description of surfaces was performed using global and directional statistical parameters. These parameters allow to determine the surface anisotropy and to divide the .joints into three groups of similar morphology according to a given direction. Each sample of the same group is submitted to the same normal stress but to different shear rates ranging from 5 to 20 gm/s. The influences of normal stress and shear rate on the mechanical behavior of the discontinuities were investigated, as well as the influence of the sample morphology on its dilatancy behavior. The morphology data of upper and lower walls also permit to quantify the contact areas before testing. After the shear tests, sheared surfaces were scanned again and reconstructed according to the shearing direction. Based on the topography data of joint surfaces obtained before and after shearing, damage zones that occurred during shearing were located for both walls of each .joint. These characterizations of joint surfaces contribute to a better understanding of the shearing behavior of natural discontinuities.

The adaptive significance of differences of root morphology, anatomy and physiology from three ecotypes of reed(Phragmites communis Trin.)

Reeds are widely distributed in drought and high salt conditions of northwestern China. Leaf epidermal micromorphology, anatomy, chloroplast ultrastructure and physio-chemical characteristics due to long-term adaptation in the natural habitats of common reed （Phragmites communis Trin.） contrasted considerably among three different ecotypes： dune reed （DR）, Gobi salt reed （GSR） and swamp reed （SR）. The main objective of the present study is to determine the adapting characteristics of morphology, anatomy and physiological responses of thin roots in DR, GSR and SR. The results show that root length density was higher in SR and few root hairs were observed in DR. Cross-section anatomical features show that each ecotype has an endodermis and exodermis, while cortex thickness and proportion of root cortical aerenchyma and stele in root structure varied among the three ecotypes. The stele and xylem share a larger area in DR compared to GSR and SR. GSR has a large proportion of the cortex with radialized distribution of aerenchyma cells spacing, and the cortex has a peripheral, mechanically stiff ring in the exodermis. SEM and TEM microscope images show that GSR has a scle- renchyma ring with high lignification in the exodermis. The physio-chemical parameters show that GSR had a higher level of stress tolerance than DR. These findings indicate that developed water-absorbing tissues were largely distributed in the root structure of DR, and a main framework with supporting function spacing with aerenchyma was dominant in GSR in the long term adaptation to their natural habitats, respectively.

基于能量最小化的CCGA焊点形态仿真研究

为了确定某陶瓷柱栅阵列(CCGA)器件实现高焊接可靠性时的工艺参数组合范围,并研究焊点形态随不同参数变化的规律,以钎料润湿角、钎料体积以及焊柱偏移量作为关键变量因素,利用基于能量最小化原理的Surface Evolver软件,计算了不同因素水平组合下的实际焊点形态,并对参数化建模过程进行了详细介绍。通过对比形态结果与焊点可接收标准,寻找能够产生合格焊点的参量范围,为实际焊点微连接生产工艺提供合理的工艺指导。

PBGA焊点形态对疲劳寿命的影响

通过Surface Evolver软件预测了塑料球栅阵列(PBGA)焊点形态,将焊点形态结果导入Ansys软件中进行-55~125℃热循环仿真实验,通过Coffin-Masson模型预测焊点寿命。选取焊点钎料量、焊点高度、下焊盘直径作为影响焊点寿命的主要因素进行了3因素3水平正交实验,通过均值响应分析得到了影响凸点寿命的最敏感因素及最优形态尺寸组合。结果表明对焊点寿命影响最大的因素为下焊盘半径,其次是钎料量,最后是焊点高度,且上下等大的焊盘具有较好的可靠性。

基于多形态学成分分析的图像融合

将多尺度分解与稀疏表示相结合,提出了一种基于多形态学成分分析(MCA)的图像融合算法。采用基于联合稀疏表示(JSR)的方法融合卡通子图像中的冗余和互补信息,并利用基于方向特征的方法融合具有更多细节信息和噪声的纹理子图像。结果表明,提出的图像融合算法在主观视觉效果和客观评价指标上均优于先进的图像融合算法。

再定位咬合板治疗颞下颌关节盘可复性前移位的临床疗效和形态学评价

目的:观察再定位咬合板对颞下颌关节盘可复性前移位的临床疗效和治疗后颞下颌关节的形态学改变。方法:选取21例颞下颌关节盘可复性前移位患者,共36侧关节盘发生移位,戴用再定位咬合板治疗(6.8±1.4)个月,评价治疗1周和治疗结束时的临床疗效,治疗前和治疗结束时拍摄MRI,治疗前、治疗1周和治疗结束时拍摄CBCT,用于评估颞下颌关节盘形态、位置和关节间隙的改变。结果:治疗1周和治疗结束时关节弹响(有效率分别为80.95%和90.48%)和疼痛(有效率均为88.89%)均改善。治疗后部分关节盘恢复正常形态(双凹型占66.67%),部分(72.22%)关节盘完全复位;盘-髁距离减小(1.87±2.05)mm、盘-髁角度减小(17.75±11.57)°(P<0.05)。治疗1周和治疗结束时关节前间隙较治疗前均减小,上、后间隙均增大(P<0.05);治疗结束时关节前间隙较治疗1周增大,后间隙减小(P<0.05),关节上间隙变化无统计学意义(P>0.05)。结论:再定位咬合板治疗颞下颌关节盘可复性前移位可有效缓解症状,改善关节盘形态和位置,进而协调颞下颌关节盘-髁位置关系。

无托槽隐形矫治器在儿童前牙美学治疗中的应用效果及对舒适满意度和咀嚼功能的影响

目的:研究无托槽隐形矫治器在儿童前牙美学治疗中的效果,并观察是否影响患儿的舒适满意度及咀嚼功能。方法:本文采用前瞻性研究,选择笔者医院2018年1月-2022年1月行前牙正畸治疗的86例患者为研究对象,随机将患者分为观察组和对照组,每组43例。观察组患儿采取无托槽隐形矫治器矫治,对照组患儿采取传统固定矫治器矫治。比较两组患儿的治疗美学效果、咀嚼指标、上气道形态、颞下颌关节、矫治测量指标以及并发症之间的差异。结果:观察组患儿的前牙美学分类为Ⅰ类的比例显著高于对照组(P<0.05);治疗后,两组患儿的美观度、舒适度、固定力、语言功能满意度以及咀嚼效率评分均显著提升,且观察组患儿评分均显著高于对照组(P<0.05);L1MP、SNA、LPW、UPW方面,两组患儿均改善明显,且观察组较对照组更优(P<0.05);两组患儿的关节窝深度、关节结节倾斜角、髁突长轴、矢状面倾斜角、髁突上部高、髁突相对位置显著改善,且观察组的相关指标均优于对照组(P<0.05);两组患儿的U1-NA、L1-NB、U1-APg、U6-PtPNS均显著降低,且观察组显著低于对照组(均P<0.05);两组患儿的牙龈感染、周围组织炎症反应、口腔不适发生概率比较,差异无统计学意义(P>0.05)。结论:无托槽隐形矫治器应用于儿童前牙美学治疗中,能显著提升患儿舒适满意度和咀嚼功能,治疗效果显著。

膝关节骨性关节炎并内翻畸形股骨髁软骨退行性变观察研究

目的膝关节骨性关节炎并内翻畸形股骨内侧髁软骨退行性变及超微结构观察。方法收集2018年11月至2021年10月行人工全膝关节置换术的55例膝关节骨性关节炎并内翻畸形患者的股骨髁,股骨内髁设为观察组,股骨外髁设为对照组。两组分别进行大体观察、HE染色、番红O-固绿染色及电镜下观察。结果大体观察:观察组股骨髁关节面不光滑,色泽灰暗,部分软骨剥脱有软骨下骨外露;HE染色观察:观察组软骨细胞排列不规整,潮线紊乱,软骨下骨板异常增厚,对照组股骨髁软骨退变程度较轻;番红O-固绿染色观察:观察组软骨层着色强度不均匀,番红染色在成簇状软骨细胞周围深染,软骨表面染色不均,软骨基质及细胞数量减少,软骨层与软骨下骨边界不清;扫描电镜下观察:观察组关节面凹凸不平,存在大量凸起、裂隙,对照组表面较为平整,可见软骨表面有散在均匀的软骨颗粒。结论膝关节骨性关节炎并内翻畸形股骨内髁关节中钙化层和软骨下骨的改变对骨性关节炎发病机制及病情发展起着重要作用。

考虑实际接触三维粗糙度退化的软岩节理剪胀规律预测模型

为预测岩石节理的剪胀变形行为,分析了恒法向荷载作用下实际接触微凸体三维粗糙度在剪切过程中的退化规律,提出了一个适用于软岩节理的剪胀曲线预测模型。在剪切荷载作用下节理法向位移的变化是节理在三角形微凸体侧面爬坡上升行为与爬越一些微凸体顶点后闭合行为的叠加,爬坡行为与闭合行为引起的位移都正比于节理最大可能剪胀角。最大可能剪胀角退化的实质是实际接触节理微凸体平均等效倾角的退化。通过分析初始剪切与残余应力阶段的节理形貌特征,提出了计算初始最大可能剪胀角与残余应力阶段剪胀角的模型。基于软岩节理不发生突然脆性破坏的假设,进一步通过研究剪切过程中节理微凸体退化规律,量化了最大可能剪胀角的变化规律。定量了节理爬坡行为、闭合行为与最大可能剪胀角之间的关系,进而提出了节理剪胀规律预测模型,通过试验验证了模型的有效性。模型可较准确预测软岩节理的剪胀规律,并可合理描述节理初始阶段剪切压密行为。

人工关节植入物涂层力学性能评价

目的对多孔型人工关节植入物的涂层性能(包括涂层形貌和涂层力学性能)进行分析,总结目前主流产品的涂层性能范围,为新产品的设计研发提供参考,同时为远期植入物取出分析提供依据。方法试验中所用的涂层表面形貌、剪切强度和拉伸强度样品,分别按照ASTM F1854、ASTM F1044和ASTM F1147标准制备,涂层采用等离子喷涂技术加工。共对17套件产品(编号1~17号)的涂层表面形貌(涂层厚度、孔隙率和孔隙截距)进行试验;对编号为1~7号和15、16号产品,首先按照ASTM F1044的试验方法,进行涂层与基体之间的剪切强度试验;然后按照ASTM F1147的试验方法,进行涂层与基体之间的拉伸强度试验。对编号为17的产品,按照ASTM F1044和ASTM F1147的试验方法,分别测试复合涂层和单纯钛涂层的剪切和拉伸强度。结果全部产品中,共15套产品(占比88.2%)涂层厚度300~500μm;金属涂层的产品共16套(编号1~16),其中11套(占比68.75%)涂层孔隙率30%~50%,14套(占比87.5%)涂层孔隙截距50~150μm;涂层的力学性能与基体材质无关;添加羟基磷灰石(HA)后的复合涂层的剪切强度和拉伸强度与纯金属涂层相比,均明显降低。结论针对多孔涂层人工关节的设计制造,其涂层的性能可以参考以下指标:涂层厚度300~500μm,涂层孔隙率30%~50%,涂层孔隙截距50~150μm;可以根据产品的用途选择基体材质;在设计含有HA的复合涂层的植入物时,应考虑结合力较低对产品性能的影响。该性能指标范围能够为远期临床取出物分析提供对照。

一种联合空谱特征的沥青路面裂缝检测方法

文章提出了一种基于高光谱图像的沥青路面裂缝检测算法,旨在解决传统方法下裂缝检测精度低、误检较多的问题。本方法利用高光谱成像技术获取道路的空间-光谱信息,并通过裂缝与路面的光谱信息差异提取裂缝,同时利用裂缝的空间特征信息对目标进行阈值分割、形态学运算等以此来提取裂缝主干,进而联合空间-光谱特征检测结果进行数学运算以实现对沥青路面裂缝的精确检测。实验结果表明,与ACI、VIS2算法相比,本文算法的F1-score分别提升了14.11%和29.03%,证明了该方法的有效性,同时针对不同类型和尺寸的裂缝目标表现出了高检测精度、强抗干扰性和显著的鲁棒性。

基于钻孔摄像的岩体结构面参数快速提取研究

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