Separation occurring during the drop weight tear test of thick-walled X80 pipeline steels

A separation phenomenon occurring during the drop weight tear test of commercial thick-walled API （American Petroleum Institute） X80 strip steel was investigated in this work. Microstructural analysis showed that the band structure of bainite elongated along the rolling direction works as the initiation sites of separation. The propagation of separation can be promoted not only by the occurrence of the band structure of martensite/austenite constituent, prior austenite grain boundaries, and elongated bainite, but also by fine acicular ferrite and bainite. Wide separation formed in the former case, while the narrow one appeared in the latter case. acicular ferrite in thick-walled X80 pipeline steel in order Some methods were proposed to obtain fine and homogeneous to minimize the occurrence of separation.

Design and application of a multichannel"cross"hot tearing tendency device:A study on hot tearing tendency of Al alloys

Hot tearing is one of the most serious defects during the casting solidification process.In this study,a new type of multichannel"cross"hot tearing device was designed.The hot cracks initiation and propagation were predicted by the relationship between temperature,shrinkage force and solidification time during the casting solidification process.The reliability and practicability of the multichannel"cross"hot tearing device were verified by casting experiments and numerical simulations.The theoretical calculation based on Clyne-Davies model and numerical simulation results show that the hot tearing tendency decreases in the order:2024 Al alloy>Al-Cu alloy>Al-Si alloy at a pouring temperature of 670°C and a mold temperature of 25°C.Feeding of liquid films at the end of solidification plays an important role in the propagation process of hot tearing.The decrease of hot tearing tendency is attributed to the feeding of liquid film and intergranular bridging.

Topographic tear film trend and new parameters for noninvasive break up time test

AIM:To evaluate the quantitative and qualitative results of the noninvasive tear film break-up time(NI-BUT)test and investigate the predictive ability of the new NIBUT parameter in discriminating between normal Ocular Surface Disease Index(OSDI;scores≤12)and abnormal OSDI(scores≥13).METHODS:A total of 341 eyes of 341 volunteers who applied for routine eye outpatient control were included in the prospective study.All participants'noninvasive first tear film break-up time(NIF-BUT),noninvasive average tear film break-up time(NIAvg-BUT)and average value of the first three break-up time(A3F-BUT)were analyzed.A3F-BUT,the new NI-BUT parameter,is calculated by adding the NIF-BUT value to the 2^(nd )break-up time value that has a difference of at most 1 second from the NIF-BUT value and to the 3^(rd) break-up time and then dividing the respective sum by 3.Receiver operating characteristic(ROC)curve and forward logistic regression analyses were performed to determine the parameter that had the best predictive ability between the OSDI groups.RESULTS:The NI-BUT values of 255 eyes of 255 volunteers included in the study were analyzed statistically.The mean NIF-BUT,NIAvg-BUT,and A3F-BUT values were calculated as 5.3±3.0,8±3.1,and 5.8±3.0 seconds,respectively.All three parameters were found to be significantly lower in the abnormal OSDI group(P=0.014,0.034,and 0.011,respectively).The area under the curve(AUC)of the A3F-BUT to predict abnormal OSDI was AUC=0.625(0.529-0.720),P=0.011 and NIF-BUT was AUC=0.599(0.502-0.696),P=0.043.The A3F-BUT parameter and NIF-BUT parameters were found to be significantly efficient in discriminating abnormal OSDI.CONCLUSION:The new parameter for the NI-BUT test has more predictive ability in the discrimination of OSDI groups.

Comparison of the SchirmerⅠtest with and without topical anesthesia for diagnosing dry eye

·AIM:To determine the value of Schirmer Ⅰtest (SⅠt) without anesthesia and with topical anesthesia for diagnosing dry eye (DE). ·METHODS:Totally 220 eyes in 110 patients, male (44) and female (66), (39.56±12.67) years old diagnosed with DE were examined. SⅠt without anesthesia was performed firstly, and 15 minutes later, it was applied again in the same person after topical anesthesia with 0.5% proparacaine hydrochloride eye drops. The wetting strips counted <10mm per 5 minutes were defined positive, while ≤5mm per 5 minutes were defined strong positive. ·RESULTS:The wetting length in SⅠt after topical anesthesia was significantly lower than that in SⅠt without anesthesia(P < 0.001). The positive rate and strong positive rate of SⅠt after topical anesthesia were significantly higher than that of SⅠt without anesthesia (P <0.001). The positive rate and strong positive rate of SⅠt without anesthesia and the strong positive rate of SⅠt after topical anesthesia in patients with aqueous-deficiency dry eye (ADDE) were significantly higher than those in total patients whereas those in patients with evaporative dry eye (EDE) were significantly lower than those in total patients (P <0.001). ·CONCLUSION:SⅠt after topical anesthesia with 0.5% proparacaine hydrochloride eye drops is more objective and reliable than that without anesthesia in reflecting the status of DE, and its diagnostic value in patients with ADDE was even higher, making itself a meaningful evidence for the diagnosis and treatment of DE.

Association between the levels of prostaglandin E2 in tears and severity of dry eye

AIM: To investigate the relationship between the levels of prostaglandin E2(PGE2) in tears and dry eye disease severity based on both clinical symptoms and signs.METHODS: Tear samples were collected from 36 non-Sj?gren syndrome dry eye patients(10 males and 26 females, mean age 50.11±11.17 y). All participants completed the Ocular Surface Disease Index(OSDI) questionnaire and underwent a detailed ophthalmic examination including, tear film breakup time(TBUT), ocular surface fluorescein staining, Schirmer I test, and meibomian gland assessment. The level of PGE2 in tears was measured using enzyme-linked immunosorbent assay(ELISA). The independent associations between tear PGE2 levels and other variables including demographics, OSDI scores, TBUT, Schirmer scores, ocular surface staining scores, and stage of meibomian gland dysfunction(MGD) were evaluated using linear regression analysis. RESULTS: The mean PGE2 level in tears of dry eye patients was 537.85±234.02 pg/mL. The tear PGE2 levels significantly positively correlated with OSDI scores(R=0.608, P<0.001), however, they did not significantly associate with TBUT(R=0.153, P=0.373), Schirmer scores(R=-0.098, P=0.570), ocular surface staining scores(R=0.282, P=0.095), and stage of MGD(R=-0.107, P=0.535).Male sex was significantly negatively correlated with tear PGE2 levels.CONCLUSION: The levels of PGE2 in tears are positively correlated with dry eye symptoms. However, no significant association was found between tear PGE2 levels and the results of other common dry eye diagnostic tests.

Validity of subjective assessment as screening tool for dry eye disease and its association with clinical tests

AIM: To determine the role of subjective assessment using Mc Monnies dry eye questionnaire in diagnosing dry eye disease and its association with clinical tests.METHODS: There were 500 patients screened for dry eye using Mc Monnies dry eye questionnaire between May to October 2013 at the outpatient Department of Ophthalmology of a medical college hospital. All 500 patients were subjected to clinical tests. Dry eye was defined as having one or more symptoms often or all the time. Positive signs were if one or both eyes revealed tear film breakup time(TBUT) of ≤10s, a Schirmer test score of ≤10 mm, a Rose Bengal staining score of ≥1, a Lissamine green staining score of ≥1 or existence of meibomian gland disease(≥grade 1). Statistical analysis was performed to describe the distribution of symptoms and signs, to assess the correlations between Mc Monnies score(MS) and variable clinical signs of dry eye, and to explore the association between dry eye symptoms and variable clinical signs. Analysis was performed using software package Epi info. A Probability(P) value using Chi-square test of 【0.005 was taken as significant.· RESULTS: Dry eye prevalence with symptoms(questionnaire), Schirmer test, TBUT, Rose Bengal staining and Lissamine green staining was 25.6%,15.20%, 20.80%, 23.60%, and 22.60% respectively. Among those with severe symptoms(MS】20), 75.86% had a low TBUT(【10s), 58.62% had a low Schirmer’s I test(≤10 mm),86.20% had Rose Bengal staining score of ≥1, 79.31%had Lissamine green staining score of ≥1. We found statistically significant associations between positive Schirmer test and arthritis(P 【0.002), dryness elsewhere(P 【0.001), contact lens use(P 【 0.002), systemic medication(P 【0.0001), sleeping with eyes partly open(P 【0.002), history of dry eyes treatment(P 【0.0001),environmental factors(P 【0.001), swimming(P 【0.001).· CONCLUSION: Subjective assessment plays an important role in diagnosing dry eye disease. There is strong correlation between MS and Schirmer test, TBUT,Rose Bengal staining and Lissamine green staining in normal as well as marginal and pathological dry eye.

拨号试验——内侧半月板后根部撕裂未识别的预测因素

目的:通过拨号试验评价内侧半月板后根部撕裂(medial meniscus posterior root tear,MMPRT)对胫骨外旋的影响;评估MMPRT隧道拉出法修复对恢复胫骨病理性旋转的作用。方法:本回顾性研究纳入了40例在2022年1月至2023年1月期间接受内侧半月板后根隧道拉出(pull-out)法修复术的患者。通过对患者手术前、后患侧及健侧膝关节屈曲30°/90°拨号试验的检查,评估胫骨外旋的变化。结果:40例MMPRT患者年龄56.4±7.5岁,体重指数24.1±3.0 kg/m^(2),其中男性6例(34%),女性34例(85%),从损伤到接受手术的中位时间为3.8±2.9月。患侧术前30°和90°拨号试验提示的胫骨外旋角度分别为31.34°±5.38°、36.75°±6.62°;患侧术后30°和90°拨号试验提示的胫骨外旋角度分别为24.24°±5.88°、24.76°±5.47°,与术前比较均下降,差异有统计学意义(P=0.00)。患侧手术前后30°和90°拨号试验提示的胫骨外旋角度差异分别为7.10°、95%CI[6.01°,8.19°]和11.99°、95%CI[10.68°,13.29°],均有显著性差异。患侧与健侧拨号试验提示的胫骨外旋角度差值比较,术前30°和90°分别为8.33°、95%CI[7.32°,9.33°]和13.03°、95%CI[11.82°,14.23°],二者差异均有统计学意义;术后30°和90°分别为0.48°、95%CI[-0.25°,0.98°]和0.34°、95%CI[-0.02°,0.70°],二者差异均无统计学意义。结论:内侧半月板后根部撕裂患者拨号试验提示胫骨外旋增加,pull-out法修复内侧半月板后根能够恢复这种病理性胫骨外旋。30°和90°拨号试验所示的胫骨外旋角度增加可以提示内侧半月板后根部撕裂。因此,在内侧半月板后根部撕裂时,应谨慎解释拨号试验的结果。

基于底摩擦试验的缓倾边坡滑移拉裂破坏过程研究

顺层边坡一旦失稳,具有规模大、危害性强的特点。针对缓倾顺层边坡滑移—拉裂型破坏,采用底摩擦物理模型试验,结合PIV粒子成像技术以及MATLAB后处理方法,分析了缓倾顺层边坡滑移—拉裂型破坏过程中的宏微观特征。研究结果表明:PIV和MATLAB的后处理所得结果与宏观观察结果相吻合,计算结果能够反映出不同边坡结构下的位移矢量特征,并对变形特征进行分区;滑移—拉裂式破坏过程分为三个阶段,裂缝产生阶段、裂缝扩展阶段和破坏阶段。裂缝产生阶段边坡后缘首先产生竖向张拉裂隙,裂缝扩展阶段裂缝向深部扩展,破坏阶段边坡上部岩体沿层面中的软弱结构面滑动。对缓倾边坡滑移拉裂破坏过程的研究成果,能够为类似边坡的滑动机制分析提供一定参考。

养阴润目方核桃灸联合玻璃酸钠滴眼液治疗干眼症临床研究

目的:观察养阴润目方核桃灸联合玻璃酸钠滴眼液治疗干眼症临床疗效。方法:选取64例干眼症患者,按随机数字表法分为治疗组及对照组各32例。对照组接受玻璃酸钠滴眼液治疗,治疗组接受养阴润目方核桃灸联合玻璃酸钠滴眼液治疗。比较2组临床疗效,比较2组治疗前后泪液分泌试验(SIT)值、泪河高度(LTMH)、非接触泪膜破裂时间平均值(NIBUTav)、眼表疾病指数(OSDI)评分、角膜荧光染色评分(FL)、睑板腺评分、睑脂性状评分的变化。结果:治疗后,2组SIT、NIBUTav指标值及治疗组LTMH指标值治疗前后比较,差异均有统计学意义(P<0.05);治疗组SIT、LTMH、NIBUTav指标值均高于对照组,差异均有统计学意义(P<0.05)。治疗后,2组OSDI评分、睑脂性状评分及治疗组FL评分治疗前后比较,差异均有统计学意义(P<0.05);治疗组OSDI评分、FL评分均低于对照组,差异均有统计学意义(P<0.05)。治疗组临床疗效总有效率为86.67%,对照组总有效率为56.67%,2组比较,差异有统计学意义(P<0.05)。结论:养阴润目方核桃灸联合玻璃酸钠滴眼液治疗干眼症临床疗效较好,可改善泪液分泌量及泪膜稳定性,缓解临床症状。

基于无损检测技术的矿山采掘设备磨损修复工艺研究

针对矿山采掘设备关键部件的磨损问题,构建一套集无损检测、磨损分析、再制造修复于一体的磨损修复工艺。该工艺采用X射线、超声等无损检测技术精确表征磨损状态,引入机器学习算法智能分析磨损机理,优化再制造工艺参数,并融合电子计算机断层扫描(Computed Tomography,CT)检测、在线监测等手段实现修复质量闭环控制。斗齿再制造实验验证了该工艺可将关键部件磨损程度降低92.3%,使用寿命提高5.1倍,为矿山采掘设备实现低成本、高效率维护保障提供新思路。

600 MPa级管线钢DWTT落锤撕裂试验

管线钢是当前重要的能源用钢,其材料的韧性是油气管道安全运行的重要技术指标之一。针对某钢厂600 MPa级管线钢生产初期落锤撕裂试验结果不合的原因进行了研究,通过调查试验钢的生产工艺,对比不同层冷温度下的落锤撕裂试验结果,进一步分析落锤试样撕裂断口位置的金相组织、夹杂物、带状组织与带钢层冷温度的关系。结果认为,600 MPa级管线钢DWTT落锤撕裂试验不合是由于落锤试验样品取样位置的带钢层冷温度偏高,导致该区域显微组织析出了大量碳化物,使得带钢韧性降低、脆性提高。层冷温度在200~400℃,显微组织稳定,碳化物析出明显降低,试验钢种钢材的韧性性能和落锤撕裂性能稳定,能够满足产品要求;层冷温度在400℃以上,随着层冷温度的提升,钢材的韧性性能和落锤撕裂逐步降低。

某车型千斤顶固定座处车身钣金撕裂破坏问题与解决

分析某车型千斤顶固定座处车身钣金撕裂破坏问题,发现在千斤顶固定与限位不充分的情况下,系统振动导致钣金疲劳开裂。设计多种千斤顶固定方案,通过比较筛选确定改进方案。采集试验场载荷谱并进行加速处理,对最终改进方案进行随机振动疲劳分析,结果表明改进方案满足要求,台架试验验证改进方案的有效性。

优化器械清洗流程在降低眼科手术器械损耗中的应用

目的探讨优化器械清洗流程在降低眼科手术器械损耗中的应用,为提高器械清洗质量、保证临床用械安全提供依据。方法选取2019年7月至2020年8月医院所用300件眼科手术器械作为研究对象,采用随机数字表法分为两组,每组150件。对照组采用传统清洗方法,观察组优化器械清洗流程。比较两组器械清洗合格率(分别采取目测法和镜检法评价清洗合格情况)、器械损耗率、器械灵活度、隐血试验结果。结果目测法结果显示,两组器械清洗合格率差异无统计学意义(P>0.05);镜检法结果显示,观察组器械清洗合格率高于对照组(P<0.05)。观察组器械损耗率低于对照组(P<0.05),器械灵活度高于对照组(P<0.05),隐血试验阳性率低于对照组(P<0.05)。结论优化眼科手术器械清洗流程可提高清洗质量,提升器械清洗合格率,减少器械损耗,延长器械使用寿命。

精杞明目汤治疗结膜松弛症的泪液功能改变

目的观察精杞明目汤治疗结膜松弛症的泪液功能改变。方法 36例(72眼)结膜松弛症患者随机分为精杞明目汤组与对照组,每组18例,对照组以人工泪液局部治疗,精杞明目汤组在对照组局部治疗的基础上加用精杞明目汤口服治疗,连续用药3个月。2组治疗前后分别进行泪膜破裂时间(break-up time,BUT)测定、Schirmer试验、泪液羊齿状试验检查。结果精杞明目汤组治疗前BUT为(7.72±2.90)s,治疗后为(10.38±3.97)s,差异有显著统计学意义(t=-7.781,P=0.000);对照组治疗前BUT为(7.84±3.02)s,治疗后为(9.24±4.17)s,差异无统计学意义(t=-1.669,P=0.104);2组治疗前氉后比较差异均无统计学意义(t=-0.211、1.539,P=0.834、0.128)。2组治疗前Schirmer试验结果差异无统计学意义(t=0.029,P=0.977),精杞明目汤组治疗前后差异有显著统计学意义(t=-6.077,P=0.000),对照组治疗前后差异无统计学意义(t=-0.993,P=0.328),2组治疗后差异有统计学意义(t=2.179,P=0.033)。2组治疗前泪液羊齿状试验结果差异无统计学意义(χ2=0.34,P=0.95),精杞明目汤组治疗前后差异有显著统计学意义(χ2=11.17,P=0.01),对照组治疗前后差异无统计学意义(χ2=0.31,P=0.96),2组治疗后差异无统计学意义(χ2=7.14,P=0.07)。结论以养阴生津法组成的精杞明目汤治疗结膜松弛症可显著稳定泪膜、促进泪液分泌,改善泪液中的黏蛋白。

轻薄型金属反平面撕裂破碎试验研究

为解决报废汽车及家用电器的破碎及回收处理问题,利用拉伸试验,获取轻薄型回收金属材料的力学性能参数;在考虑强化效应的基础上,将材料本构关系简化为双线性模型;通过裤形撕裂试验,观察到轻薄型回收金属发生大小相等、方向相反的两次弹塑性弯曲变形,因此裤形撕裂试验过程中外力所做功主要由金属材料的撕裂功和裤腿的弹塑性弯曲功两部分组成;分析研究轻薄型回收金属材料撕裂破碎过程的特点,将单位面积裂纹表面的撕裂比功作为表征材料撕裂性能的特征参数;比较轻薄型回收金属在不同加载速度下的撕裂比功,发现撕裂比功在一定范围内对加载速度的变化不敏感。研究表明,轻薄型金属材料的拉伸断裂比功较相应板材的撕裂比功大一个数量级,这表明撕裂方式更适合于报废汽车及家用电器的破碎加工处理。

基于实验结果讨论断层破裂与强震物理过程的若干问题

基于断层摩擦滑动实验、含凹凸体断层的变形破坏实验、断层撕裂扩展的实验、交叉断层的变形实验等多种实验结果并结合前人的工作 ,讨论了与断层破裂与强震物理过程相关的若干问题。研究表明 ,断层的整体滑动引起其两侧块体弹性应变的释放 ,是强震发生的原因 ,因此构造活动区具有较大尺度、结构连续且简单、介质均匀的断层 (或断层段 )是产生强震必备的构造条件 ,深部新生断层(盲断层 )向上撕裂扩展产生强震 ,尚需“弱层”提供“解耦”条件以便断层发生整体滑动。强震孕育过程中包含着凹凸体的破裂 ,断层面上凹凸体的尺度、强度及数量决定着前震活动的特征、强震动态破裂过程以及前兆现象。由断层分割的块体通过边界断层的交替滑动、以“框动”的方式运动 ,因此块体周边的断层上强震活动具有交替性。

固溶处理对7A55铝合金断裂韧性的影响

采用金相组织观察、拉伸实验、Kahn撕裂试验、扫描电镜、透射电镜等方法研究固溶处理对7A55铝合金断裂韧性的影响。研究结果表明:固溶温度对7A55铝合金断裂韧性影响显著,7A55铝合金在450～490℃时固溶,随着温度上升,可溶性粒子减少,断裂韧性增加,到480℃时断裂韧性达到最大值;当温度超过480℃时,由于晶粒的长大,断裂韧性又开始下降;7A55铝合金有很大的淬火敏感性,当以慢速淬火时,晶界非共格析出物尺寸粗大,对断裂韧性不利。

镁合金的热裂行为测试研究

以ZQS 2 0 0 0型双试棒合金热裂 线收缩仪的机械部分为基础 ,提出了一种用以测试镁合金热裂行为的新的测试方法。铸造时采用覆膜砂作为铸型材料 ,解决了镁合金在浇注过程中的燃烧问题 ;通过A/D转换 ,用微机对凝固过程中的温度、应力和收缩信号数据进行采集和进一步的处理 ,并描绘其曲线。试验测得 ,在通常凝固条件下 ,AZ91合金并不按平衡相图凝固 ,而是有共晶相析出 ;AZ91合金最容易产生热裂的温度在实际凝固结束温度 (42 4℃ )

轧辊材质摩擦磨损性能测定装置的研制

介绍了一种模拟实际工况条件,测定轧辊磨损量及摩擦系数的试验装置。经实验验证,该装置可方便、准确地测定出在冷轧状态下轧辊的磨损量及摩擦系数,从而为轧辊的选材及实际应用提供有力的参考依据。

结膜松弛症泪液黏蛋白及球结膜杯状细胞的研究

目的:评价结膜松弛症泪液功能及结膜杯状细胞的组织病理学及超微结构改变。方法:结膜松弛症与正常对照组各30例(60眼)进行泪膜破裂时间(tearbreakup time,BUT)SchirmerⅠ试验、泪液羊齿状试验(tear ferning test,TFT)检查。对10例松弛球结膜组织和10例对照组球结膜对应区组织,采用PAS,AB和HE染色,对照观察组织病理及超微结构改变。结果:结膜松弛症组BUT(7.72±2.90s)较对照组(14.40±3.68s)减少明显(P<0.05)。基础Schirmer试验中结膜松弛症组(13.20±4.07mm)较对照组(16.73±4.41mm)明显降低(P<0.05)。结膜松弛症组泪液中羊齿状结晶明显减少,与对照组间比较差异有显著意义(P<0.05)。结膜松弛症球结膜上皮中的杯状细胞密度为2.75±2.68/100个上皮细胞,对照组为4.64±3.25/100个上皮细胞,两组间差异无显著性(t=1.42,P=0.172)。随着结膜松弛症程度加重,球结膜杯状细胞密度降低。结膜松弛症球结膜杯状细胞组织形态和超微结构有异常。结论:结膜松弛症泪膜稳定性下降、泪液分泌减少,泪液中黏蛋白减少,结膜杯状细胞数量减少,超微结构有异常。