The dynamic behavior of journal bearing lubricated by non-Newtonian fluid (conforms to the Carreau model) during start-up is investigated. A mixed lubrication model consisting of a GT (Greenwood-Tripp) contact equation and a transient modified average Reynolds equation is proposed. The transient modified average Reynolds equation is established with the average flow method. The effect of non-Newtonian lubricant, surface roughness, external load, relative clearance, and accelerating time on the dynamic behavior of journal bearings during start-up is analyzed. The results show that increasing the relaxation time, external load, and relative clearance, as well as decreasing the power-law exponent, composite root-mean-square roughness, and accelerating time can reduce the contact time and facilitate the rapid formation of hydrodynamic lubrication during start-up.

The average turbulent Reynolds equation, influenced by asperity contact and turbulence, was derived based on the average flow method. Combined with the asperity contact model, a mixed turbulent lubrication model was established. The mixed lubrication performance of worn journal bearings supplied with axial end oil under turbulent lubrication was analyzed. The results show larger wear defects can significantly reduce the bearing's maximum mean film pressure and friction power. The larger lubricant inlet pressure can significantly increase the maximum mean film pressure and friction power when the relatively worn defect is large. Wear defects and end oil supply have opposite effects on the mixed turbulent lubrication. The mixed turbulent lubrication model can also applied to the thrust bearing.

High-speed train brake discs face severe service conditions and subsequently risk of material failure during emergency braking. Thermal fatigue cracking is a major concern leading to catastrophic disc failure and is regarded as a primary service bottleneck in rapid rail transportation. Our proposed work establishes a numerical prediction model to estimate thermal fatigue crack initiation and propagation in low-alloy steel. We used a modified Cockcroft-Latham criterion and material property tests to determine the critical crack initiation value. Through numerical simulations and in-situ experiments, we observed plastic deformation at the median temperature of the thermal fatigue cycle and found that tailored material composition improves brake disc fatigue performance. This research aims to enhance understanding of the cracking mechanism and improve the reliability of brake systems for high-speed trains.

Erythropalum scandens Blume, an emerging medicinal plant with great potential for drug development, also possesses high edible value. In this study, we investigated the genetic diversity of the germplasm of E. scandens obtained from different geographical locations using inter simple sequence repeat (ISSR) markers. For this purpose, 18 ISSR primer pairs with a distinct background and adequate polymorphism were selected. We established an optimal ISSR–PCR reaction system (20 µL) with the following parameters: 1 µL DNA template (60 ng µL−1), 1.2 µL primers (10 µmol µL−1), 10 µL MasterMix, and 7.8 µL H2O. A total of 183 loci were amplified using the 18 primer pairs, of which 121 (66.12%) indicated polymorphism. Moreover, 34 germplasms of E. scandens exhibited genetic similarity coefficients ranging from 0.7104 to 0.9563, genetic distances ranging from 0.0447 to 0.3420, Nei’s genetic diversity index of 0.1946, and Shannon’s information index of 0.2982, suggesting high intraspecific genetic diversity. UPGMA cluster and PCoA analyses distinguished the germplasm of E. scandens obtained from Guangxi from those collected from Guangdong, Hainan, Fujian, and Guizhou. However, the Mantel correlation analysis revealed that the genetic variation among the 34 germplasms of E. scandens was not significantly related to geographical distance. The analysis of the genetic background of wild and cultivated germplasms of E. scandens can help guide variety selection and breeding. Furthermore, the present study revealed the genetic background and affinities among 34 germplasms of E. scandens. Overall, our findings lay the foundation for the conservation and utilization of germplasm resources, identification and classification of varieties, and variety selection and improvement of E. scandens at the molecular level.

[目的]建立瘤果紫玉盘SCoT-PCR最佳反应体系,并筛选出适宜的SCoT引物,为瘤果紫玉盘种质鉴定分类、亲缘关系分析和遗传多样性分析提供理论参考.[方法]以广西河池、百色、柳州、南宁4份瘤果紫玉盘野生种质为试材,通过单因素试验和正交试验对瘤果紫玉盘SCoT-PCR反应体系的DNA模板用量、引物用量和Mix预混液用量3个因素进行优化,并使用优化后最佳反应体系进行SCoT引物筛选.最后将SCoT-PCR最佳反应体系和筛选出的引物用于瘤果紫玉盘种质的遗传多样性分析.[结果]单因素试验结果显示,DNA模板用量为40～70 ng,引物(10 μmoL/L)用量为1.0～1.4 μL,Mix预混液用量为9.0～12.0 μL范围内扩增效果较好,通过L16(43)正交试验确定瘤果紫玉盘的SCoT-PCR最佳反应体系20.0 μL:DNA模板(40 ng/μL)1.0 μL,引物(10 μmoL/L)1.2 μL,Mix预混液10.0 μL,7.8 μL ddH2O.利用最佳反应体系筛选出26条适用于瘤果紫玉盘的SCoT引物,并确定了各引物最适的退火温度.26条SCoT引物在4份瘤果紫玉盘材料中共扩增出305个基因位点,其中多态性位点204个,多态性比率为66.89%,平均每条引物扩增出11.7个基因位点,有8.7个多态性位点.4份瘤果紫玉盘种质的平均等位基因数(Na)为1.7377,平均有效等位基因数(Ne)为1.5344,Nei's基因多样性指数(H′)为0.3053,Shannon指数(I)为0.4449.4份瘤果紫玉盘间的遗传相似系数为0.5443～0.6492,遗传距离为0.4320～0.6083,说明4份瘤果紫玉盘种质间存在较大的遗传变异,遗传多样性水平较高.[结论]建立的SCoT-PCR最佳反应体系和筛选出的26条SCoT标记引物扩增效果较好,可用于瘤果紫玉盘种质资源的鉴定分类、亲缘关系分析和遗传多样性分析.

中国特有植物瘤果紫玉盘(Uvaria kweichowensis),分布范围狭窄,数量稀少.为系统了解广西瘤果紫玉盘的资源数量、分布现状及资源利用等情况,2016-2022年作者团队通过实地走访、问卷调研等形式,对全区9个县开展了瘤果紫玉盘种质资源调查和种质收集工作,共收集到瘤果紫玉盘资源95份.调查结果显示:瘤果紫玉盘多年生藤本植物,成熟叶革质,主要分布在广西隆安县、天峨县等9个县共197株,生境为海拔650～1100 m之间的喀斯特石山区,依托乔木向上攀附生长,野生资源数量稀少,个体之间距离较远,基本上处于无保护状态,分布地群众有采集瘤果紫玉盘叶片治疗疾病或用于茶饮的习惯.通过种子播种、枝条扦插的形式开展了瘤果紫玉盘种质资源的繁育试验,结果表明不同来源的瘤果紫玉盘种子发芽率在25.7％～34.4％,扦插成活率在4.4％～14.4％,总体成活率较低.本研究探讨了瘤果紫玉盘受威胁的主要因素,提出了保护措施,为广西民族药瘤果紫玉盘种质资源的保护、挖掘和创新利用提供基本依据.

To study the static behavior of misaligned journal bearings under heavy loads using a non-Newtonian lubricant (pseudoplastic fluid, the flow behavior obeys a power-law relationship). And the generalized average Reynolds equation for rough journal bearing under pseudoplastic lubricant flow is derived. The establishment method of the model equation adopts the average flow method of Patir and Cheng. The numerical solution of bearing performance parameters applies the finite difference method and the successive over-relaxation method. And surface roughness can partially offset the effects of liner elastic deformation and lubricant shear thinning. The generalized average Reynolds equation derived in this paper is not only used in the research of hydrodynamic lubrication but also can be used in the research of mixed lubrication.

The stability and reliability of braking system are essential factors for the safe operation of high-speed trains. In the proposed work, tribological properties of a newly developed brake disc material namely BD-1 were studied considering the thermal-mechanical effects, as well as the evolutions of wear debris, were particularly examined. The tribological properties were also compared with an existing commercial brake disc material namely BD-2 in text. Friction and wear tests were carried out on BD-1 and BD-2 against a commercial brake pad material (BP) to simulate the real emergence braking conditions of a 350 km/h high-speed railway. The thermal-mechanical coupling effects of the friction velocity, wear mass, temperatures and the friction coefficient were investigated. Local wear track and wear debris were analyzed by using SEM and EDS. Results show that the shape and size of wear debris evolve as the dominant wear mechanism varies during braking tests. As the sliding speed increases from 250 to 1250 rpm, the debris may become fine particles, then into a mixture of lamellar shape and flake shape, and finally becomes fine particles again at high speed. The maximum size of wear debris is first from 20 μm to 65 μm, and then down to 10 μm. As the local area temperature increased by more than 400 °C, debris adhere to the surface forming an adhesive layer that may act as a lubricant. Debris may help to form an adhesive lubrication layer and undertake plastics defor-mation at the speed range of 500–1000 rpm. The local area temperatures prompted the wear debris adhesion and oxidation. After reaching a certain speed limit, a uniform third body appears to protect the material surface from high speed and high temperature. Results suggested that the BD-1 could be a good candidate braking material for high-speed railway applications.

The modified average Reynolds equation for friction pairs with arbitrary three-dimensional rough surfaces lubricated by couple stress fluid is derived by the average flow method. And the performance parameters under the effect of couple stress, surface roughness, journal misalignment, and thermal effect are obtained with the finite difference numerical method. The surface roughness factor plays an important role even though the nominal eccentricity ratio is small. With the increase of the nominal eccentricity ratio, the greater values of the couple stress parameter, the greater values of performance parameters except for the dimensionless maximum oil film temperature and the dimensionless friction power. With the increase of the degree of misalignment, the greater values of the couple stress parameter, the greater the dimensionless maximum average film pressure, the dimensionless load capacity, and the dimensionless misalignment moment. As the value of the couple stress parameter is increased, the greater values of the dimensionless surface roughness, the greater values of the performance parameters except for the dimensionless side leakage. This research can widely use in various forms of friction pairs such as thrust bearings, sliding bearings, piston ring-cylinder liners.

对风电轴承润滑脂和轴承的磨损进行了分析,并监测了某风场主轴轴承、变桨轴承和偏航轴承所用润滑脂的宽温度范围滴点、铁磁性颗粒浓度、Fe含量、Cu含量、机械杂质.结果表明:部分风机主轴轴承润滑脂宽温度范围滴点发生大幅降低,最高降低73℃,建议对滴点降低超过30℃的主轴轴承润滑脂进行更换.同时,该风场部分风机的变桨轴承和偏航轴承润滑脂中存在大量的机械杂质,杂质尺寸主要集中在10～75 μm,杂质主要来源于轴承的磨损,主要成分为Fe.表明部分风机变桨轴承和偏航轴承发生了较严重的磨损,应密切关注风机的运行状况,并对磨损严重的风机进行维护.

Organic friction modifiers (OFMs) are widely used in lubricants. However, the mechanism of their structure–activity relationship still needs further exploration. Herein, we found that glyceryl monoelaidate (GME) with a trans double bond, exhibits a better antifriction and antiwear performance than glyceryl monooleate (GMO), the cis isomer of GME. Glyceryl monostearate (GMS) with a saturated tail group is even better. The obvious different tribological performance of three different OFMs with slight molecular structure difference is attributed to the different entropy decreasing they form a boundary film on steel surfaces, which affected their surfacial-coverage. The disclosed conformation entropy effect on surfacial-coverage of boundary film could guide the design of more novel and effective OFMs.

首先通过甲基丙烯酸二甲氨基乙酯与溴乙烷反应制得N,N,N,N-二甲基乙基甲基丙烯酰氧乙基溴化铵,利用该季铵盐对纳米片层材料Laponite进行化学改性来提高Laponite与苯乙烯(St)的相容性,然后以辛基苯酚聚氧乙烯(10)醚(OP-10)为助乳化剂通过原位Pickering乳液聚合制备了PSt/Laponite复合乳液.利用透射电镜、扫描电镜、X射线衍射、差示扫描量热分析、热重分析等测试手段探究了乳化体系、改性程度等对复合乳液的制备及性能的影响.最后,将PSt/Laponite复合乳液与苯丙乳液(PSB)共混后成膜,考察了PSt/Laponite复合乳液用量及Laponite改性程度对复合乳胶膜力学性能和透水汽性的影响.结果表明,OP-10与Laponite复配有助于获得稳定的PSt/Laponite复合乳液,La-ponite的改性程度对复合微球的大小及形貌有重要影响,Laponite的引入亦使复合体系的Tg和热稳定性有所改善;将5％PSt/Laponite组分引入PSB体系所得乳胶膜拉伸强度(Rm)由8.3 MPa提升至14.8 MPa,同时其透水汽性较加入同比例不改性PSt/Laponite复合乳液所得乳胶膜提升了19％.

针对轴承钢表面材料,选择了4款风力发电机组偏航轴承、变桨轴承、主轴承和电机轴承润滑脂,并对比研究了其在钢表面的极压抗磨性及对轴承钢表面的磨损特性.结果 表明,不同风电脂由于其类型不同,对钢表面的极压抗磨性及对轴承钢表面的磨损特性不同.在轴承发生磨损的同时,轴承脂中添加剂与轴承钢表面的摩擦化学反应,以及钢表面发生的轻微氧化,会造成轴承钢表面粗糙度上升,硬度下降.

采用C、Mn、Al、Ni和Cr等元素制备了新型冷成形弹体钢.测试了奥氏体区和奥氏体+马氏体区的维氏硬度,观察了新型冷成形弹体钢不同变形量低温回火和相同变形量不同温度回火后的组织,计算了不同工艺处理后试样中的奥氏体体积分数,研究了变形量和回火温度对组织分布的影响.结果 表明:形变诱导马氏体含量随压缩变形量的增大而增加,压缩后晶面间距有减小趋势.回火前后组织内都有孪晶分布.马氏体含量随回火温度升高而减少,使马氏体含量快速减少的回火温度在400℃以上.中温回火后材料硬度异常增大,高温回火后材料微观形貌发生显著变化,且组织内位错密度下降.

为监测某风场5台风机的齿轮箱润滑油的运行状态,对影响齿轮油衰变和齿轮箱寿命的指标,如齿轮油黏度、黏温性能、水分、酸值和污染物等进行监测,分析在用润滑油在不同运行时间下各个指标的变化情况.结果表明:在不同运行时间下各齿轮油的运动黏度有一定变化,但未发生明显衰变,对齿轮箱不会产生较大影响;酸值和水分的测试结果也显示齿轮油尚未发生明显的劣化;在不同运行时间下齿轮油的动力黏度变化不大,表明齿轮油并未受到严重的剪切作用,其结构没有发生明显的变化;温度对齿轮油有重要的影响,随着温度的降低,齿轮油的动力黏度逐渐变差,因此,齿轮箱的运行应控制在合适温度范围内.污染度测试结果表明,齿轮油的污染度已超标,最高达到22/20/17,最低为18/16/11,可采用更换过滤器或者安装旁路过滤系统的方式来控制该风场风机齿轮箱润滑油的污染以延长齿轮箱的使用寿命.

以天门冬良种“桂冬1号”茎段为试材,研究生长素NAA和细胞分裂素6-BA的不同比例对天门冬芽器官脱分化、再分化、芽增殖和诱导不定根发生的影响,以期为天门冬产业化良种繁育及有效保护野生种质资源提供参考依据.结果 表明:茎段在0.1％ HgCl2的最佳消毒时间为10 min,无菌活体获得率76.08％.最佳的初代培养基为MS+6-BA1.0 mg·L-1 +NAA 0.10～0.20 mg·L-1,外植体可在一个培养周期(30 d)完成再分化和脱分化的过程,且芽诱导率83.00％以上.在添加6-BA 0.5 mg·L-1和IAA 0.1 mg·L-1的MS培养基上,芽增殖系数最高为3.41.在添加NAA1.50 mg·L-1+ IBA 1.0 mg·L-1的1/2MS培养基上,生根率最高为85.55％,平均根数5.0条,根长2.2～3.1 cm.

Biomimetic microstructure has been used widely in the fields of microfluidics, micro-mixers, flow drag reduction, tribology, etc. When solid surface is modified with microstructure, it will inevitably influence the solid-liquid interfacial behaviors, such as adhesion, surface wetting, shear viscous resistance, and interfacial slip. Surface anisotropic wetting can be achieved by using either of anisotropic surface microstructure and chemically heterogeneous patterned surface, or both of them. And anisotropic wetting properties can be used to control the micro-flowing behaviors, like mixing, flowing direction and speed. The effect of microstructure on the surface wetting behavior is closely related to the size, shape and arrangement of microstructure. In the paper, the influence of micro-groove size on liquid anisotropic wetting behavior is studied. The results indicate that the droplet wetting state of the patterned surface used is Cassie state. According to the experimental results, we can see that the liquid flows easily along the groove direction with small motion resistance, thus resulting in a small contact angle. While the water droplet has a higher flowing resistance in the direction perpendicular to the groove direction due to the energy barrier caused by micro-groove, thus showing a larger contact angle. Meanwhile, the water droplet shows pinning and jump behavior during the spreading in the direction perpendicular to the micro-groove direction. The contact angle along the micro-groove direction θ// increases with groove width G increasing, and decreases with ridge width R increasing, which means that the parallel direction contact angle θ// is inversely proportional to the solid fraction R/(R + G). And the experimental contact angle θ// shows good consistence with that obtained from theoretical Cassie model. While the contact angle of water droplet perpendicular to groove direction θ⊥ almost keeps no change with groove width G nor ridge width R. Both the droplet deformation ratio L/W and contact angle ratio of the two featured direction θ⊥/θ// are proportional to the solid fraction R/(R + G). The water droplet shows anisotropic wetting behaviors, which means that the liquid motion resistances are different in these directions. The high droplet deformation ratio L/W and the high contact angle ratio θ⊥/θ// correspond to the large difference in motion resistance. And surface wetting behavior has a great influence on the micro-flowing behavior. Thus, the micro-flowing behavior can be regulated by changing the microgroove size. The present research can conduce to the understanding the wetting mechanism and flowing behaviors of liquid droplet on patterned surface.

为筛选育苗基质,探讨天门冬播种条件对种子发芽率的影响,以桂冬1号种子为试验材料,研究了不同浸种时间、贮藏时间、播种月份、浸泡水温、发芽温度、不同育苗基质条件对天门冬发芽率及植株生长的影响.结果表明,浸种时间大于12 h的处理与发芽率呈正相关,浸种96 h的发芽率最高,达96.67％,比未浸种(对照)提高了25％以上;种子发芽率随着贮藏时间的延长而降低,即采即播的发芽率最高,达到86.33％,贮藏时间12个月的发芽率仅有8.33％;4月和10月播种的发芽率较高,分别达到90.00％和87.67％;不同浸泡水温对种子的发芽率无显著差异;温度(恒定)对天门冬种子发芽率具有显著影响,25℃ 条件下种子发芽率最高,达78.67％,常温次之,30℃、35℃明显下降;以黄泥+珍珠岩+泥炭+椰糠(体积比2:1:1:1)为播种基质和育苗基质种子发芽率最高,达89.58％,幼苗长势最佳.

铜基粉末冶金材料具有优秀的热传导性、热稳定性和摩擦磨损性能,已经被广泛用于高速列车制动摩擦领域.目前,我国高速列车的制动闸片仍主要依赖进口,亟需进行国产化替代.综述了成分组成、制备工艺和服役工况对铜基粉末冶金材料摩擦性能的影响,指出了各因素间存在的耦合关系.提出应以我国运营实际工况为基础进行创新研发的思路,从而形成高速列车国产铜基粉末冶金摩擦材料产品体系,助力高铁走向世界.

轴承中的润滑脂在长期使用过程中会存在大量的固体颗粒,这些固体颗粒尤其是金属颗粒能对运动表面产生严重的磨损,从而引起设备功能失效.在各种磨损形式中,磨粒磨损对设备造成的损失最为严重.为了研究润滑脂中磨粒对钢界面摩擦学性能的影响,考察了磨粒尺寸、磨粒浓度、载荷和转速对材料磨损的影响.结果 表明,在一定范围内,随着磨粒尺寸和浓度的增加,钢材料表面的磨损量也在增加,且磨粒浓度的增加对材料的磨损程度大于磨粒尺寸的增加对材料的磨损程度.另外,转速和载荷的增加也会提高材料表面的磨损量.