The Lubricating Effectiveness of S-Mo Extreme Pressure Additive and Its Anti-wear Mechanism

A kind of novel compound containing S and Mo elements was synthesized. Its chemical structure was characterized by elemental analysis, IR and 3MR. hs anti-wear property and the load-carrying capacity, as an extreme pressure （EP） additive of lubricating oil, were investigated using a four-bull tester. The experimentul results show that the additive exhibits a superior anti-wear property and a high load-carrying capacity . The presence of other additives does not interfere with the anti-wear prnperty of the extreme pressure additive. The influences of load and temperature on the propert） of the additive were examined. The possible mechanism uas investigated by means of sufface analysis of the tested steel ball specimen , using XPS. The lubricatian films formed on the rubbing surface are mainly composed of MoS2, MoO3 and MoO2.

Key technologies for construction of Jinping traffic tunnel with an extremely deep overburden and a high water pressure

Jinping traffic tunnel is one of the deepest traffic tunnels in the world with a maximum overburden of 2 375 m and the overburden over 73% of its total length is larger than 1 500 m. The tunnel is 17.5 km long and designed to provide a shortcut road between two hydropower stations： Jinping I and Jinping II of the Jinping Hydropower Project, located on Yalong River, Liangshan State, Sichuan Province, China. The tunnel is so deep that building any shafts is impossible. The construction starts from both ends （east and west ends）, and the construction length from the west end is 10 km with a blind heading. This paper deals with an overview of this project and analysis of the engineering features, as well as key technologies developed and applied during the construction, including geological prediction, rock burst prevention under a super high in-situ stress, sealing of groundwater with a high pressure and big flow rate, ventilation for a blind heading of 10 km, wet spraying of shotcrete at zones of rock burst and rich water, etc. The application of the new technologies to the construction achieved a high quality tunnel within the contract period.

ROLLING CONTACT FATIGUE BEHAVIOR OF CERAMIC BALLS LUBRICATED BY LUBRICANTS WITH EXTREME PRESSURE ADDITIVES

An experiment is conducted to investigate the effects of lubricant10#, which contains extreme pressure additives T304 and T305, on the rolling contact fatigue （RCF） life of the contact pairs of a Si3N4 ceramic ball and a steel rod. The experimental investigation is carried out using a ball-rod RCF test rig. The results show that the extreme pressure additives increase the anti-contact-fatigue performance of ceramic balls; When the content of the additives varies from 1% to 5%, the increasing gradient of the RCF life curve decreases; And the oil sample with 1% T305 additive corresponds to the maximal gradient of the RCF life curve, with the RCF life being increased by about 10.77 times. The fatigue surface of the ceramic ball is analyzed with scanning electron microscope （SEM） and X-ray electron dispersion analysis（EDAX）, and the physical model of extreme pressure additives＇ increasing the RCF life of the ceramic ball is proposed. It is found that the extreme pressure additives form a corrosive film and a transfer film on the surface of the ceramic ball, which decrease the surface tangential stress, and to increase the surface energy is the most effective means for increasing the RCF life.

Numerical analysis of coal-gas flow and pressure relief on the mining method of extreme short-range protective strata

The coal-gas existing condition was ameliorated in the coal seams prone to coal-gas outburst adopting the mining method of protective strata.The gas volume and the gas pressure were reduced synchronously in the protected coal seam,and the coal seam of high permeability prone to the coal-gas outburst was changed into that of low perme- ability with no proneness to the coal-gas outburst.The D_(15)coal seam was treated as the protective strata,and the D_(16-17)coal seam was treated as the protected strata in the Fifth coal mine in the Pingdingshan Coal Mining Group.The distance between the two coal seams was 5 m averagely,clarified into the extreme short-range protective strata.The numerical analysis was based on the theory of the porous media flow with the finite ele- ment method.The gas flow process and the change mechanism of the coal-gas pressure were analyzed in the process of mining the protective strata.

Analysis of the pressure at a vertical barrier due to extreme wave run-up over variable bathymetry

The pressure load at a vertical barrier caused by extreme wave run-up is analysed numerically, using the conformal mapping method to solve the two-dimensional free surface Euler equations in a pseudospectral model. Previously this problem has been examined in the case of a flat-bottomed geometry. Here,the model is extended to consider a varying bathymetry. Numerical experiments show that an increasing step-like bottom profile may enhance the extreme run-up of long waves but result in a reduced pressure load.

Ongoing Blood Pressure Change in Both Upper Extremities: An Unusual Presentation of Aortic Dissection

Aortic dissection is a critical condition requiring immediate assessment and management. Patients with this condition usually present with severe chest pain and high blood pressure. However, because of the variety of presenting symptoms and features, it is a challenge to identify this condition, and patients are frequently misdiagnosed. The potentially critical course of aortic dissection can result in tragedy. We present the case of a 46-year-old woman who initially presented with a light headache and sensory loss in her right upper limb. She had a medical history of hypertension without regular medication, and her blood pressure (BP) was 110/67 mmHg on arrival. Four days later, she was sent to the emergency department again because she experienced transient loss of consciousness lasting for a few minutes. Her BP was 94/57 mmHg in the right arm and 89/54 in the left arm. She was admitted to the hospital, and the pulses in both upper limbs were impalpable on the following day. Chest magnetic resonance imaging (MRI) was arranged, and subsequently, aortic dissection was diagnosed. The case presented with unusual characteristics, which increased the difficulty in immediate correct diagnosis.

Analysis on Extreme Gale of Capital Airport

Observation data of extreme gale in Capital Airport during 1976-2013 were analyzed,and climate characteristics of extreme gale in Capital Airport were summarized. Moreover,three extreme gale weather processes with larger influences on December 10,2010,November 22,2011 and March 9,2013 were contrasted and analyzed,and results showed that extreme gale in Capital Airport mainly appeared during March-April or December-January. Occurrence frequency of extreme gale was the most from late afternoon to evening,and the minimum was from night to morning,while peak appeared during 14:00-15:00. Extreme gale of Capital Airport was dominated by northwest gale at the rear of cold front,and the peak occurred at the wind direction of 330°. The common effect of strong cold high pressure going south at the rear of ground cold front and highaltitude transverse trough turning vertical was main cause of extreme gale in Capital Airport,and momentum transmission below 500 hP a also had an important effect in the generation of extreme gale.

Failure Mechanism of O-Ring Seals under Extreme Operating Conditions

In this paper the behavior of an O-ring made of NBR rubber was investigated under extreme conditions. The effect of the extreme initial compression, operating pressure and extreme temperature conditions were examined. The rubber material was tested in simple tension, pure shear and equibiaxial tension modes complemented with a Dynamic Mechanical Thermal Analysis (DMTA) to capture the viscoelastic behavior of the material. For the investigation, a large-strain viscoelastic material model was developed by the authors, to take into account the large deformations caused by extreme conditions. Insufficient space during installation causes extreme initial compression consequently leading the material to crack on the contacting outer surfaces. It was found that the excessive strain and friction induced shear stress contributes primarily to this phenomenon. Extreme operating pressure causes the seal to penetrate into the gap between the shaft and the housing. This behavior damages the material and cracks appear on the seal. High strain areas were found in the proximity of the gap in the material. The analysis of the extreme operating temperature showed that during cooling the O-ring can completely loose its ability to seal at -70°C. There are three contributing factors: the speed of cooling, the temperature and the coefficient of thermal expansion.

Inhomogeneous Dielectric Target Properties for Increased Non-thermal Pressure in Laser Boron Fusion by CPA-Pulses

Based on the documentation of the invited paper and the subsequent discussion at a virtual conference,discoveries are indicated,which are summarized in the following paper for further evaluation on the topic of non-thermal forces using terms of extremely powerful components of Maxwell’s stress tensor at the interaction of CPA(chirped pulse amplification)laser pulses in the fusion plasmas of hydrogen with the isotope 11 of boron.This is caused by a recoil mechanism given by the Fresnel formulas of the suppression of the reflectivity of inhomogeneous plasma given by optical constants of the plasma properties.

极近距离煤层开采无煤柱自成巷控制方法研究

极近距离煤层传统长壁开采,受上层遗留煤柱和采空区垮落等因素的影响,下煤层开采过程中应力环境复杂、矿压显现剧烈,易诱发巷道围岩大变形。为解决上述问题,提出了极近距离条件下巷道定向切顶–约束高强支护无煤柱自成巷控制方法。通过顶板定向预裂切顶,主动改变顶板悬臂结构,切断采空区向巷道顶板的应力传递。充分利用矿山压力和岩体碎胀特性,取消煤柱留设,结合高强支护加强巷道顶板整体性,共同实现切顶自成巷。建立了极近距离煤层开采覆岩结构模型,计算了下煤层切顶自成巷巷旁支护阻力。以典型极近距离煤层为工程背景,开展了不同开采方法的数值试验对比研究,结果表明,提出的自成巷控制方法使巷道围岩应力降低59.8%,巷道顶板变形减少70.8%,并明确了极近距离煤层开采无煤柱自成巷控制机理。在此基础上,开展了典型极近距离煤层工程设计及现场应用研究,结果表明该方法有效降低了矿压显现程度,保证了自成巷的安全稳定控制。

国内外建筑围护结构风荷载规范对比研究

针对围护结构设计风荷载,分析了如下风荷载规范中的相关规定:中国GB 50009—2012、中国JGJ/T 481—2019、美国ASCE/SEI 7⁃16、日本AIJ⁃2015、澳大利亚/新西兰AS/NZS 1170.2:2021、欧洲BS EN 1991⁃1⁃4:2005、加拿大NBCC 2015。分析结果表明,国内外围护结构风荷载规范的理论基础主要包括准定常理论和风压极值理论,均将设计风荷载表示成设计风速与设计风压系数的乘积;设计风速的确定需要考虑地貌、局部地形、季节、风向、相邻建筑干扰等因素的影响,各国规范对这些因素考虑的详尽程度不一;设计风压系数则需要考虑来流湍流和特征湍流共同作用下风压的时间随机性和空间分布不均匀性、不同方向来流时建筑表面风压的差异性、建筑表面风压相关性等因素,各国规范均通过风压分区和面积折减较好地考虑了这些因素,不同之处在于不同规范所涵盖的建筑体型、考虑建筑几何参数影响的风压分区结果及面积折减的特征有所区别。

负压封闭引流联合拜尔坦敷料在糖尿病下肢溃疡治疗中的临床研究

目的探讨负压封闭引流联合拜尔坦敷料在糖尿病下肢溃疡治疗中的临床效果。方法选取2022年1月—2023年12月玉林市红十字会医院收治的100例糖尿病下肢溃疡患者为研究对象,根据治疗方式分为两组,各50例。其中实施局部创面常规换药的患者为对照组,实施负压封闭引流联合拜尔坦敷料治疗的患者为观察组。比较两组临床疗效、疼痛情况、临床相关治疗指标。结果观察组患者临床治疗总有效率(96.00%)高于对照组(84.00%),差异有统计学意义(χ^(2)=6.212,P=0.045)。治疗后,观察组患者疼痛程度评分低于对照组,差异有统计学意义(t=4.807,P<0.001)。观察组换药频率低于对照组,溃疡愈合时间及平均住院时间均短于对照组,差异有统计学意义(t=5.755、6.268、7.148,P均<0.001)。结论在糖尿病下肢溃疡治疗中实施负压封闭引流及拜尔坦敷料,疗效确切,可积极减轻患者疼痛程度,缩短相关治疗时间,促进患者恢复。

电机轴承用全氟聚醚润滑脂的研制与性能

研制了一种电机轴承用全氟聚醚润滑脂。通过对基础油,稠化剂和添加剂的考察,确定了电机轴承用全氟聚醚润滑脂由全氟聚丙醚基础油,聚四氟乙烯稠化剂,3%白炭黑,3%有机含锌盐抗磨极压剂,3%硫化异丁烯抗磨极压剂,2%纳米碳酸钙和3%有机硼酸酯抗磨极压剂组成。研制的电机轴承用全氟聚醚润滑脂的磨斑直径为0.41mm,烧结负荷P_(D)值达到7846N,最大无卡咬负荷值达到1961N,制备的全氟聚醚润滑脂与橡胶的相容性良好,达到了研制目标。(图4表9参考文献10)

不同风场中特高压换流站阀厅屋盖风压特性试验研究

特高压(ultra high voltage,UHV)换流站阀厅的金属屋面系统在风荷载作用下易发生屋面表层风揭事故。为深入探讨该类建筑屋面的风压极值特性,基于风洞试验分别探讨了大气边界层(atmospheric-boundary-layer,ABL)风、壁面射流、均匀湍流三种风场作用下的屋面风压特性,比较了平均风剖面、风速、风向、湍流强度等因素对屋面风压的影响。结果表明:阀厅屋盖迎风前缘负风压最大,且控制风向角在45°左右;壁面射流风场下平均风压系数与脉动风压系数均超过大气边界层风场的结果;风速对阀厅屋盖的负风压系数均值和极值影响较小,而湍流度对风压系数的极值影响较大;大气边界风场时,JGJ/T 481—2019《屋盖结构风荷载标准》的最不利风压系数建议值偏于安全;而在壁面射流风场下,阀厅屋盖全风向最不利风压系数在所有区域都大于JGJ/T 481—2019的建议值,设计中应加以重视。

暖季日夜复合热与成年人血压的关联及生理和行为驱动因素的定组研究

目的了解暖季日夜复合热与成年人血压的关联,探讨可能的生理和行为驱动因素。方法基于定组设计于2020年5—9月在广东省广州市番禺区对35名健康成年人进行5次连续随访,使用电子血压计测量其血压水平(每月一次),利用便携式温湿度仪器收集血压测量前7天其生活环境的温湿度,通过问卷调查收集其社会人口学资料与行为因素,使用嵌入分布滞后非线性模型“交叉基”函数的随机效应模型分析日夜复合热与成年人血压的关联,并探讨这种关联的可能驱动因素。结果与正常日相比,日夜复合热显著增加收缩压和舒张压水平,改变量分别为8.35(95%CI:2.54~14.15)和6.55(95%CI:1.49~11.60)mmHg,未观察到单独热日、单独热夜与血压的显著关联。生理驱动因素方面,暴露于日夜复合热会显著增加血管紧张素Ⅱ的水平,改变量为28.29(95%CI:1.52~55.07)pg/mL,人体超敏C反应蛋白水平也增加1.24(95%CI:0.25~2.46)mg/L。在行为驱动因素方面,暴露于日夜复合热时,研究对象的啤酒饮用量增加200.69(95%CI:79.16~322.22)mL。结论暴露于日夜复合热时,收缩压和舒张压水平显著增加。血管紧张素Ⅱ与超敏C反应蛋白水平的升高可能是其生理驱动因素,啤酒饮用量的增加可能是其行为驱动因素。

固体氢在极端压强下的超导性能

氢元素在常压下具有最简单的晶体结构和物理性质。随着压强增加,氢单质发生相变,由绝缘体转变为金属,被称为金属氢。数值模拟表明,金属氢具有高温超导电性,因此,金属氢研究也被称为高压物理领域的“圣杯”课题。利用基于密度泛函理论的第一性原理计算方法,对固体氢在极端高压(0.5~5.0 TPa)下的结构和超导电性开展了系统研究。研究结果表明:固体氢的高压相变序列为I4_(1)/amd→oC12→cI16;对于同一种结构,随着压强增加,电声耦合系数减小,费米面处电子态密度减小,特征振动频率增加,超导转变温度发生小幅变化;在2.0 TPa压强下,固体氢的超导转变温度高达418 K(库伦赝势经验值μ^(*)=0.10)。研究工作将为金属氢及其超导电性的后续理论和实验研究提供参考。

噻二唑衍生物的制备及性能评价

针对现有噻二唑衍生物制备工艺中废水化学需氧量(COD)极高的问题,探索以去离子水替代乙醇作为反应溶剂,并引入相转移催化剂促进固-液两相反应,开发了制备噻二唑衍生物的绿色环保新工艺;进而,采用红外光谱、液相色谱、质谱等手段对新工艺合成的产物进行了结构表征,采用铜片腐蚀试验和四球试验评价了合成产物的金属腐蚀抑制性能、极压性能和减摩性能。结果表明:采用新工艺合成产物过程中产生的废水COD为2000 mg/L,与传统工艺产生的废水COD(700000 mg/L)相比显著降低,说明新工艺符合绿色环保要求;采用传统工艺和新工艺分别合成了2,5-双(叔壬基二硫代)-1,3,4-噻二唑,其金属腐蚀抑制性能、极压性能、减摩性能相当,且优于市售噻二唑衍生物类金属减活剂T561。

S-N型功能分子用作多功能添加剂的缓蚀及摩擦学行为研究

利用电化学、摩擦学试验和量子化学模拟等手段,研究了巯基甲基噻二唑(MMT)和二壬基萘磺酸(DNS)这2种功能分子作为缓蚀剂的缓蚀性能和作为极压抗磨添加剂的摩擦学性能及其作用机理.电化学试验表明,DNS分子的缓蚀能力较差,缓蚀效率为58.6%;MMT分子表现出优异的缓蚀能力,缓蚀效率达93.3%.摩擦学试验表明,DNS作为添加剂时,油样的摩擦系数与PEG基础油的摩擦系数相当,磨损量增大;MMT作为添加剂时,油样的摩擦系数和磨损量较PEG基础油明显降低,极压性能较基础油明显提高.量子化学模拟结果表明,DNS分子与钢表面具有更高的反应活性,因此作为极压抗磨和缓蚀添加剂,加剧了金属的腐蚀和磨损.表面分析结果表明,DNS分子润滑下的磨斑表面主要起到减摩作用的是铁的氧化物和FeSO_(4)等.MMT分子润滑下的磨斑表面的摩擦产物为Fe_(2)(SO_(4))3、FeS_(2)、铁的氧化物以及含氮有机物.

半封闭式车站列车风压极值分布规律研究

为了研究半封闭式车站内风压极值的分布规律,对高速列车通过高铁站时引起的列车风压进行数值模拟,并通过现场实测数据验证数值模型的准确性。基于验证的数值模型,研究列车分别以250 km/h、300 km/h和350 km/h的速度通过高铁站时,两个典型区域(临近站台区Ⅰ、远离站台区Ⅱ)的风压(头波、尾波的正压和负压)极值分布规律,并提出相应的风压极值经验公式。研究结果表明:风压极值与列车速度之间呈非线性关系;相同的车速下,区域Ⅰ和区域Ⅱ内列车风压极值随着水平距离的增加呈指数函数形式衰减,而衰减的速度与高度成反比;当水平距离小于15 m时,相同高度下区域Ⅰ的头波正压极值总是比区域Ⅱ的大,而区域Ⅰ的头波负压极值的绝对值又总比区域Ⅱ的小;当水平距离超过15 m时,车站内的风压极值逐渐趋于稳定,并且区域Ⅰ内趋于稳定的风压极值要强于区域Ⅱ;所提经验公式能够较为准确地描述半封闭式高铁站内列车风压极值分布规律。研究成果可为半封闭式车站的结构设计提供参考。

下肢康复机器人联合IPC对脑损伤后肢体运动功能障碍患者下肢深静脉血栓预防效果

目的探讨下肢康复机器人联合间歇充气加压装置(IPC)对脑损伤后肢体运动功能障碍患者下肢深静脉血栓形成(DVT)的预防效果。方法通过便利抽样法选取本院2020年12月—2021年12月住院的脑损伤后肢体运动功能障碍患者90例,根据治疗方法的不同将其分为对照组和观察组,每组45例。对照组给予常规康复训练及IPC治疗,观察组在对照组基础上给予下肢康复机器人治疗,两组均在治疗3月后进行效果评价,比较两组临床疗效、美国国立卫生研究院卒中量表(NIHSS)评分、改良Barthel指数(MBI)评分、凝血-纤溶系统指标、下肢深静脉血流动力学参数、DVT发生率。结果观察组临床总有效率高于对照组(P<0.05)。观察组治疗后NIHSS评分低于对照组(P<0.05),观察组治疗后MBI评分高于对照组(P<0.05)。观察组治疗后D-二聚体(D-D)、纤维蛋白降解产物(FDP)均低于对照组,观察组治疗后凝血活酶时间(APTT)、凝血酶原时间(PT)均高于对照组(P<0.05)。观察组治疗后下肢腘静脉、股静脉、髂外静脉平均血流速度(Vm)均高于对照组(P<0.05)。观察组DVT发生率低于对照组(P<0.05)。结论下肢康复机器人联合IPC可有效改善脑损伤后肢体运动功能障碍患者神经功能及下肢血液流动速度,提高日常生活能力,纠正血液高凝状态,降低DVT发生率,值得借鉴。