膨润土润滑脂的热稳定和抗氧化性能研究

研究助分散剂、温度和抗氧化剂对膨润土润滑脂稠度的影响,认为加热温度为40℃是合适的合成温度,对膨润土润滑脂的性能和结构表征结果表明在采用丙酮为极性助分散剂和胺类添加剂作为抗氧化剂的条件下,可制备出热稳定性和抗氧化性能良好的膨润土润滑脂。     

含纳米PTFE颗粒润滑脂的润滑性能研究

在四球摩擦磨损试验机上考察纳米PTFE颗粒作为添加剂对复合钛基润滑脂摩擦磨损性能的影响,采用扫描电子显微镜分析试验钢球磨斑的表面形貌,并利用X射线光电子能谱仪检测磨斑表面化学元素的组成及状态。结果表明,在一定添加量范围内,纳米PTFE可以改善复合钛基润滑脂的摩擦磨损性能,其中纳米PTFE质量分数为3%时,复合钛基润滑脂具有最佳的抗磨、减摩性能,可使摩擦因数、磨斑直径分别降低约25.4%和18.9%。纳米PTFE颗粒在钢球表面发生摩擦化学反应,生成了一层金属氟化物,有效地抑制了摩擦表面的黏着磨损和接触疲劳。     

新型轧辊脂在棒材轧机轴承上的应用

文章介绍了新配方轧辊脂在棒材轧机轴承上的应用及其产品特性。与现用轧辊脂的应用情况进行对比,通过使用前后产品性能的分析以及现场轴承消耗的统计,新型轧辊脂在抗水性、用后产品的润滑脂特性、泵送性、对轧辊轴承润滑保养等方面优于现用轧辊轴承脂。     

Short communication: A comparison between purebred Holstein and Brown Swiss × Holstein cows for milk production, somatic cell score, milking speed, and udder measurements in the first 3 lactations

Brown Swiss × Holstein (BS × HO) crossbred cows (n = 55) and purebred Holstein (HO) cows (n = 50) were compared for milk yield, fat and protein production, somatic cell score, milking speed, and udder measurements for the first 3 lactations. Cows from a designed experiment were housed in a freestall barn at the experimental station of the federal state of Saxony-Anhalt, Germany, and calved from July 2005 to August 2008. Best prediction was used to determine actual production for 305-d lactations from test-day observations. For the first 3 lactations, BS × HO cows and HO cows were not significantly different for milk yield, fat and protein production, or SCS. Average milking time was significantly longer for BS × HO cows than for HO cows for first, second, and third lactations by 35, 51, and 30 s, respectively. Average milking speed expressed as average yield per minute was significantly lower for BS × HO cows than for HO cows for the first 3 lactations by 0.19, 0.35, and 0.19 kg/min, respectively. Front and rear teats were significantly longer for BS × HO cows than for HO cows. Furthermore, front and rear udder clearance was significantly lower for BS × HO cows compared with HO cows in first and second lactations.     

基于ASP.NET的部队办公自动化系统的设计和实现

从部队的需求分析出发,介绍了系统的架构设计思想,业务分析过程以及数据库设计和实现方案,构建了一个基于ASP.NET的部队通用网络OA系统的平台,并针对一些关键技术的实现细节进行了介绍。设计充分利用ASP.NET开发WEB程序的特点,从实际项目中总结经验,阐述了一个完整办公自动化的开发过程。     

Artificial neural networks as a basis for new generation of rock failure criteria

Conventional methods for prediction of rock strength are based on using classical failure criteria. In this study, artificial neural networks were regarded as new tools for considering the strength of intact rock in a wide range of loading condition from uniaxial tension to triaxial compression. A comprehensive data set of the values of major and minor principal stresses at failure from 1638 laboratory tests on seven rock types was collected. For each rock type, data were randomly divided into two subsets, training and test sets. Neural networks were trained using training sets to predict the value of major principal stress at failure from uniaxial compressive stress and minor principal stress. Small architecture and regularization method were adopted to avoid over-fitting problems. The same training sets were used in determining the constants of two popular empirical failure criteria, namely Bieniawski–Yudhbir and Hoek–Brown. Then, the test sets were used to examine the accuracy and generalization of the models in predicting the strength in new situations. Comparison of the results of the neural network models with those of the empirical criteria showed that the former approach always lead to less root mean squared error and higher coefficient of determination. On average, for different rock types, using ANN models led to about 30% decrease in prediction error relative to best empirical models. These models also showed better flexibility in the prediction of major principal stress at failure in both brittle and ductile failure regimes.     

掘进机自动集中润滑系统设计

根据掘进机的实际工作情况,介绍了掘进机自动集中润滑系统的选型和润滑形式的确定原则,详细阐述了掘进机各润滑点耗脂量和润滑系统中各元件参数的计算方法。经实践证明,自动集中润滑系统大大延长了掘进机的寿命和提高了掘进机的可靠性。     

Grease Resistance of Corn Zein Coated Paper

The grease resistance of corn zein coated paper was measured as related to coating level, plasticizer addition and time. Overall grease resistance ws normalized by time and expressed as percent area stained/hr (%AS. hr^-1). For a 2.2 kg coating ream^-1 of paper, %AS hr^-1 was greater than both unplasticized and plasticized 4.4 and 6.6 kg ream^-1 coating levels (p < 0.001). There was no difference in %AS hr^-1 among 4.4 and 6.6 kg ream^-1 zein coated and commercial polyethylene laminated paper (p:ME0.098). Plasticizer increased (p < 0.001) and creasing had no effect (p=0.71) on %AS hr^-1. Electron microscopy showed discontinuities in zein coating at the 2.2 kg ream^-1 level. The 4.4 and 6.6 kg^-1 ream^-1 levels showed uniform coatings.     

几种棕色色素稳定性的比较

棕色色素是食品着色物的重要部分之一。酸枣棕色素是我国首创的,颜色和稳定性可与焦糖,可可色媲美。主要发色物需深入研究。     

基础油对锂基脂安定性的影响

为研究基础油对锂基脂安定性能的影响。在相同酸碱比例、皂份和相同工艺等条件下,采用12-羟基硬脂酸体系稠化相同黏度不同组分的基础油,制备系列通用锂基润滑脂,分析基础油黏度指数、苯胺点和饱和烃含量对锂基润滑脂安定性能的影响。结果表明:随基础油黏度指数、苯胺点和饱和烃含量的升高,锂基脂工作锥入度、抗水喷雾和压力分油增大,而十万次剪切差值和蒸发量减小;基础油黏度指数、苯胺点和饱和烃含量三者与锂基脂安定性能呈现正相关性,与锂皂的溶解性呈现负相关性。