Experimental determination of mechanical properties and short-time creep of AISI 304 stainless steel at elevated temperatures

The high temperature properties of AISI 304 stainless steel were studied. Basic data about the employed experimental equipment, testing procedures, and specimen geometry were given. The experimental setup was used to obtain stress-strain diagrams from tensile tests at room temperature as well as several elevated temperatures. Furthermore, the specimens were subjected to short-time creep tests at various temperatures. Stress levels for creep testing were established as a percentage of yield stress. The results indicate that at lowered temperatures and lower stress levels, AISI 304 stainless steel can be used as a sufficiently creep resistant material.

Investigation of the friction coefficient evolution and lubricant breakdown behaviour of AA7075 aluminium alloy forming processes at elevated temperatures

The lubricant behaviour at elevated temperatures was investigated by conducting pin-on-disc tests between P20 tool steel and AA7075 aluminium alloy. The effects of temperature, initial lubricant volume, contact pressure and sliding speed on the lubricant behaviour(i.e. evolutions of the coefficient of friction(COF) and the breakdown phenomenon) were experimentally studied. The evolutions of COF at elevated temperatures consisted of three distinct stages with different friction mechanisms. The first stage(stage Ⅰ) occurred with low friction when the boundary lubrication was present. The second stage(stage Ⅱ) was the transition process in which the COF rapidly increased as the lubricant film thickness decreased to a critical value. In the final plateau stage(stage Ⅲ), lubricant breakdown occurred and intimate contact at the interface led to high friction values. At the low friction stage(stage Ⅰ), the value of COF increased with increasing temperature. The increase in temperature, contact pressure and sliding speed as well as the decrease in initial lubricant volume accelerated the lubricant breakdown.

Elevated liver enzymes portends a higher rate of complication and death in SARS-CoV-2

BACKGROUND Severe acute respiratory syndrome coronavirus 2,or coronavirus disease-2019(COVID-19),has infected millions worldwide since its discovery in Wuhan,China in December 2019,but little is still known about the disease process.Preliminary research in China notes liver function tests(LFTs)abnormalities are common in COVID-19 patients,suggesting decreased hepatic function,and that abnormalities in LFTs are related to complicated disease course and negative outcomes.However,there has been limited large-scale data assessing COVID-19’s association with liver dysfunction and negative outcomes.AIM To investigate how COVID-19 affects the liver function and disease course in patients infected with the virus treated at Henry Ford Hospital from March to September 2020.METHODS A total of 8028 patients infected with COVID-19 were identified and included in the study at a single academic center.Data from medical charts on laboratory testing including aspartate aminotransferase(AST),alanine aminotransferase(ALT),alkaline phosphatase(AP),and bilirubin levels,past history of liver disease,and disease course indicators including hospital admission,intensive care unit(ICU)admission,intubation,and death were recorded and analyzed.Elevated liver enzymes were defined as ALT/AST greater than 60,AP greater than 150,or bilirubin greater than 1.5,super-elevated liver enzymes were defined as ALT/AST greater than 120,AP greater than 300,or bilirubin greater than 3.0.RESULTS A total of 8028 COVID-19 patients were identified and included in the study.Data from medical charts on LFTs(namely,AST,ALT,AP,and bilirubin levels),past history of liver disease,and disease course indicators(hospital/ICU admission,intubation,death)were recorded and analyzed.LFTs from 3937 patients were available for interpretation.45% were found to have elevated or super-elevated LFT.When compared to COVID-19 patients without elevated LFTs,this cohort was found to have significantly higher odds of hospital admittance,ICU admission,intubation,and death(all P<0.001).248(3.1%)had a history of liver disease.Those with elevated and super elevated LFTS had significantly higher odds of having a past history of liver disease(P<0.001).CONCLUSION The findings from this study suggest that in patients who have tested positive for COVID-19,those with elevated and super elevated liver enzyme levels have significantly higher odds of hospital admittance,ICU admittance,intubation and death in comparison to those COVID-19 patients without elevated liver enzyme levels.

Design of New Elevator Pressure Guide Plate and Its Test Device

Pressure guide plate plays a certain role in the safe operation of elevator.Based on understanding the respective performance of new and old pressure guide plates,this paper analyses the problems existing in the original pressure guide plate.It also conducts stress analysis according to the function of pressure guide plate on elevator,and designs a new type of pressure guide plate combined with technological capability and equipment.According to the stress characteristics,a test device is designed and a comparative test is made between the new type of pressure guide plate and the old in order to test the reliability of the new type of pressure guide plate.The test proves that the new pressure guide plate of elevator can meet the requirements of product use and safe operation of elevator products.

基于深度学习的电梯层门安全检测关键技术研究

通过深度学习进行小目标检测,提出了可以在电梯正常运行情况下,对电梯层门关键部件的异常状态进行检测分析判断的一种新型的检测电梯层门关键部件的检测方法。为了对本文设计的电梯层门关键部件检测分析设备进行验证,本文搭建了电梯层门关键部件检测分析实验平台。通过现场验证,该系统实现了对在用电梯的电梯层门关键部件检测分析等功能。

曳引式电梯限速器安全钳联动试验的失效分析及预防措施

在城市发展的大背景下,电梯成为高层建筑不可或缺的辅助设备之一,但随之而来的电梯安全事故不断增加。为了防止各种电梯安全事故的发生,电梯厂家根据国家相关标准要求给电梯添加了各种安全装置。其中,电梯限速器-安全钳联动装置是一种安全装置。当电梯发生失控超速运行时,它能可靠地制停轿厢。电梯限速器-安全钳联动装置的失效将直接导致电梯在发生失控超速的情况下无法将轿厢可靠制停,从而引发电梯安全事故。因此,文章主要分析了曳引式电梯限速器-安全钳联动试验的失效情况,并提出了相应的预防措施。

基于机械性能的便携式电梯层门强度测试装置

传统电梯层门强度的测试方法是利用移动的撞锤,通过控制撞锤移动速度和距离实现不同参数测量,并测量样品变形量、应力、应变等指标的实验过程。针对传统实验装置较为繁琐的问题,设计了一种可以方便携带的电梯层门强度的测试装置,用于检验电梯层门强度是否符合要求。在设计上注重体积小、质量轻、携带方便的理念,采用手握式结构,可单手操作,便于在层门任意位置实施检测。装置通过旋动调节旋钮、调节力值刻度进而调节测试力的大小。施力盘与电梯层门的间距采用专用工装进行限定,使作用力精确、稳定。配备5 cm^(2)和100 cm^(2)两种规格施力盘,符合相关规范要求,并通过快捷的连接设计使施力盘的更换简单、快速、易操作。

电梯制动器故障分析及其检验检测研究

为实现对电梯运行状态的实时监测,增强其故障分析和检验检测工作的针对性,提高电梯运行的安全性,在介绍几种常见电梯制动器结构和电气原理的基础上,列举电梯制动器的常见故障形式,包括控制故障、制动器磨损、弹簧压力不均和电磁线圈铁心故障等。之后提出一种基于信息采集的故障预判系统,利用物联网和数据分析手段,实现对电梯制动器故障的精准预判,更为合理地安排维保周期。最后,从功能性检验和电气系统检验两方面重点阐述电梯制动器检验检测的相关要求及关注重点,并提出相应的制动器安全防护措施,包括提高检验检测质量、强化制动器维修养护等。以期为电梯制动器的运行监管、维修养护和检验检测提供有力的技术支持,确保电梯的安全、可靠运行。

一起电梯接地故障保护检验引发的思考

电梯接地故障是一种常见的故障类型,在不具备接地保护系统的控制电路中,接地发生故障时,会引起控制线路的意外短路,从而使各种电气开关失效,电梯在失去保护的情况下启动运行,造成严重的伤亡事故。笔者通过一个检验案例对电梯接地保护进行了分析,揭示了接地故障可能导致的设备缺陷和潜在事故风险,最后还详细地论述了电梯接地保护的检验方法和要点,为实际检验工作提供了一定的参考和指导。

电梯安全性能的影响因素与检测技术分析

阐述电梯安全性能的影响因素,分析电梯检验检测中的问题及原因,提出强化策略,包括规范电梯检验程序和方法、统一操作流程和评估指标、完善电梯检验监管机制和责任分配。

基于涡流传感器阻抗变化的导电材料缺陷检测

涡流检测是应用在导电材料电磁无损检测和评估中的技术。在常温25℃下对试样表面缺陷区域的涡流分布进行有限元仿真分析,提出一种通过涡流传感器线圈阻抗变化对高温100℃与150℃下导电材料表面缺陷进行检测的方法。分别在常温和高温的条件下进行线圈阻抗测量并产生相应的阻抗3D表面颜色图,通过被测试片表面阻抗的振幅和相位分析其是否存在缺陷。测试结果证明当试件暴露于高温环境中,可以通过涡流传感器线圈阻抗的变化判断被试导电材料表面是否存在缺陷,并且给出了不同温度下缺陷和线圈阻抗之间的关系。

城市高架混凝土现浇变宽梁桥横梁开裂处置措施及效果分析

针对某软土地基城市高架混凝土现浇变宽箱梁桥施工过程中出现的横梁开裂问题,结合裂缝分布特点,提出了相应的加固处置措施,并采用空间杆系模型与ANSYS实体有限元模型相结合的方式对其加固效果进行分析。研究结果表明:与加固前相比,加固后横梁正截面抗弯承载能力提升了9.0%,斜截面抗剪承载力提升了38.9%;加固后横梁正截面抗弯、斜截面抗剪以及裂缝断面直剪承载力均满足要求,且横梁正截面和斜截面抗裂性均满足要求,加固效果较为显著。横梁荷载试验结果表明,加固后横梁总体抗弯工作性能和开裂位置附近的抗剪工作性能良好。所提出的增大截面和增设预应力综合加固方案,可为其他工程提供参考。

Ⅰ期综合心脏康复对ST段抬高型心肌梗死急诊经皮冠状动脉介入术后患者的疗效

目的 探究Ⅰ期综合心脏康复对于急性ST段抬高型心肌梗死(ST elevation myocardial infarction, STEMI)患者急诊经皮冠状动脉介入治疗(percutaneous coronary intervention, PCI)后的康复疗效。方法 选取2021年6月至2022年6月国家电网公司北京电力医院心血管内科收治的72例急性ST段抬高型心肌梗死并行急诊PCI的患者作为研究对象,采用随机数字表法将其随机分为常规治疗组和康复组,每组各36例。常规治疗组采用常规护理与健康宣教,康复组在此基础上实施Ⅰ期综合心脏康复,包括初期评估(心血管综合评估)、运动训练(运动训练和呼吸训练)、日常活动指导与健康教育、出院评估(6分钟步行试验和Barthel指数评估)。比较两组患者出院时Barthel指数(BI)得分、出院时6分钟步行试验测试距离(6MWD)、住院期间及出院1个月内主要不良心血管事件(major adverse cardiovascular event,MACE)的发生率和住院时间等。结果 干预后,康复组6MWD和BI得分均优于常规治疗组,差异有统计学意义(P <0.05);住院期间及出院1个月内MACE发生率,康复组低于常规治疗组,差异有统计学意义(P <0.05);康复组患者的住院时间低于常规治疗组,但差异无统计学意义(P> 0.05)。结论 Ⅰ期综合心脏康复训练应用于STEMI并行急诊PCI术后患者,可提高患者的运动能力、提高其日常活动能力、降低发病早期MACE的发生率,有利于患者尽快回归家庭与社会,改善其生活质量,具有较高的临床应用价值。

基于嵌入式技术的全自动电梯控制柜电磁兼容检测控制系统设计

针对目前电梯控制柜电磁兼容检测方法智能化程度低、操作繁琐且缺乏电梯系统状态监测的问题,文章设计了一套电梯控制柜电磁兼容检测控制系统。其构建了“上位机+下位机”的控制系统架构,开发了基于ARM的嵌入式控制器,设计了自动检测流程和控制系统上下位机应用软件,使电梯控制柜具备传感器信号采集、CAN总线通信等功能,实现了控制柜电磁兼容性能化检测的以及电梯系统状态的实时监测。使用该系统对电梯控制柜进行传导抗扰度、电压暂降、电压中断、电快速瞬变脉冲群检测和浪涌试验,并对传感器信号异常、电源故障和通信异常故障进行模拟试验,结果显示,该电梯控制柜电磁兼容检测控制系统运行稳定、数据采集准确、操作简单,且对各种故障类型均能准确、高效识别。该系统可以满足电梯生产厂家及检测机构的电磁兼容检测需求,且与以往检测方法相比,减少约67%的检测人力投入。

电梯安全性能定量测试分析仪的设计及应用

本文梳理了TSG T7001—2023《电梯监督检验和定期检验规则》和GB/T 7588.1—2020《电梯制造与安装安全规范第1部分:乘客电梯和载货电梯》中对几个重要检验项目的技术要求,这些检验项目需要对电梯的加速度值进行定量测试分析。传统的测试方法存在一定局限性,检验效率和检验质量不高。本文研发了一种电梯安全性能定量测试分析仪,能够对电梯三轴加速度进行测量,对数据进行分析,得到轿厢运行的振动峰峰值、运行速度、行程、制停距离、减速度和制停时间等数值。可以实现对电梯轿厢意外移动保护装置安全性能的检测,具备自动触发和人工触发2种模式,可实现累积误差消除,自动判断轿厢启停,对制动触发点自动进行捕捉,有效地提升检验效率和检验精度。

煤矿摩擦式提升机钢丝绳更换工艺

煤矿摩擦式提升机钢丝绳的定期更换对于保障矿井提升系统的安全性至关重要。针对矿井摩擦式提升机的实际情况,设计一套钢丝绳更换工艺流程,包括旧钢丝绳拆卸、新钢丝绳选配与安装、连接与张紧等关键环节。通过现场试验与数值仿真相结合的方法,评估该工艺的应用效果。结果表明,更换后提升机运行平稳性提高,钢丝绳张力分布更加均匀。无损检测结果显示,钢丝绳缺陷明显减少,证明了该工艺的可行性和有效性,为类似工况下钢丝绳的更换提供了参考。

电梯永磁曳引机的在线退磁检测

永磁同步电机具有功率大的优势,但在电梯曳引应用中存在机械强度低与不可逆退磁的问题。其中,退磁问题会直接影响电梯运行安全,甚至导致电梯失速与冲顶。鉴于此,提出了一种基于变参数SMO的在线退磁检测方法,根据永磁同步电机在电梯曳引中的结构特征,选择采用改进饱和函数与可变开关增益的方式解决SMO应用中的抖振问题。结果表明,新型在线退磁检测方法具有较高的检测精度,可满足电梯永磁曳引机在线检测工作要求。

Clinical features and surgical treatment of double elevator palsy in young children

AIM： To describe the clinical features of congenital double elevator palsy（CDEP） and to evaluate various surgical outcomes between the standard Knapp and augmented Knapp procedures, based on improvements in primary eye position and ocular motility.METHODS： Twenty-two patients with CDEP at Shanghai Children＇s Hospital were enrolled from July 2014 to January 2018. The forced duction test（FDT） was negative in 21 patients, aged 8 mo to 12 y（mean 5.4 y）. Patients were divided into two treatment groups： 16 patients underwent the standard Knapp procedure（group A）, with or without horizontal squint procedure; and 5 patients underwent the augmented Knapp procedure（Foster procedure; group B）. One patient underwent inferior rectus recession in the affected eye and superior rectus recession in the sound eye because of a positive FDT. The pre-and postoperative vertical deviations in the primary position and ocular motility were compared in the two groups.RESULTS： Twenty-one eyes of the 22 patients（95%） were aligned within 10 prism diopters（PD）, and all patients（100%） reached ≥25% elevation improvement after surgery. The average corrected vertical deviation in group B was statistically better than that of group A. For group A, the vertical deviation in the primary position decreased from 24.75Δ±8.35Δ to 4.56Δ±8.07Δ after surgery, for an improvement of 23.06Δ±6.51Δ（P〈0.05）. In group B, the decrease was from 35.00Δ±5.00Δ（range 30Δ-40Δ） to 1.00Δ±2.24Δ, for an improvement of 34.00Δ±4.18Δ（P〈0.05）. There were significant differences between the pre-and postoperative elevation in each group（group A, P〈0.05; group B, P〈0.05）. The average scale of improved elevation in group B（1.80±0.45） was not significantly better than that of group A（1.69±0.87; Z=-0.732, P=0.548）. The average follow-up periods lasted 21 mo in group A and 18 mo in group B.CONCLUSION： For vertical deviations 〈30Δ, the standard Knapp procedure can be chosen. For deviations greater than 30Δ-40Δ, the Foster procedure should be chosen. Because of our early interference, the inferior rectus（IR） muscle did not show mechanical restriction. Monocular elevation deficiency（MED） should be diagnosed early so that complications will be reduced and the procedure will be easier for the surgeon.

Anti-anxiety activity of successive extracts of angelica archangelica linn.on the elevated t-maze and forced swimming tests in rats

OBJECTIVE:Angelica archangelica Linn.is widely used in food and liquor preparations and also in Kashmiri folk medicine to reduce anxiety.We evaluated the anxiolytic effect of successive extracts of A.archangelica linn.(SAE) on rats tested in the elevated T-maze test(an animal model of generalized anxiety) at doses that exhibit antidepressant-like activity in humans.METHODS:A.archangelica(1 kg) was subjected to successive extraction in a soxhlet apparatus with solvents [petroleum ether(40-60℃),chloroform,ethyl acetate,methanol and decoction with water] in order of increasing polarity(yield:6.9%,7.3%,5.1%,11.88% and 8.2% w/w,respectively).SAE were evaluated for anxiolytic effects using the elevated T-maze and forced swimming tests in rats.RESULTS:Oral dosing of diazepam(1 mg/kg) and extracts(50,100 and 200 mg/kg) clearly showed an anxiolytic-like profile in the elevated T-maze test:it increased one-way escape and decreased inhibitory avoidance on the first,third and seventh day.In the forced swimming test,imipramine and SAE showed antidepressant-and anxiolytic-like effects as reflected by increased climbing time,swimming time and decreased immobility time on the first,third and seventh day.Aqueous and methanol extracts showed the most,petroleum ether(40-60℃) and chloroform intermediate,and ethyl acetate the least anxiolytic activity(*P<0.05,**P<0.01,***P< 0.001) in both models.CONCLUSIONS:These results suggest the anti-anxiety activity of various extracts of A.archangelica and strongly justify its use in traditional Indian medicine for the treatment of anxiety.

Distribution Patterns of Medicinal Plants along an Elevational Gradient in Central Himalaya,Nepal

This study aimed to compare the distribution patterns and trends of plant parts used among different groups of medicinal plants, geographical regions,and between medicinal plants and all vascular plants.We used the published sources for elevation records of 2,331 medicinal plant species to interpolate presence between minimum and maximum elevations and estimated medicinal plant richness for each 100-m elevational band. Monte Carlo simulations were used to test whether differences in elevational distribution between different groups of medicinal plants were significant. Total number of medicinal plants as well as different groups showed unimodal relationship with elevation. The elevational distributions of medicinal plants significantly differ between regions and between medicinal plant groups.When comparing the richness of all medicinal plants to all vascular plants,Monte Carlo simulations indicated that the numbers of medicinal plants are higher than expected at low elevations.The highest richness of medicinal plants at low elevation could be possibly due to favorable environmental factors such as high temperature, rainfall,sunlight or due to higher density of human population and thus higher pressure on use of any plants in lower elevations.