纳米润滑油添加剂在农业机械上的应用研究

现代农业机械在生产实践中面临两大极端使用环境,首先由于工作要求的特殊性,常处于超负荷工作状态;其次除春耕秋收工作时间外,农用机械处于长期停放状态。针对农用机械两大特点,本文依据纳米润滑油添加剂的作用机理与农业机械特殊的工作环境,阐述了纳米润滑油添加剂对于农业机械的适用性。     

链斗式挖泥船磨损原因与应对策略

链斗式挖泥船在浅滩整治,河道疏通方面起着不可估量的作用。文章分析了从设备管理的角度分析了下导轮轴承易于磨损的原因,并从润滑、密封和轴承材料等三方面提出了应对策略,效果显著。     

Effect of design parameters of flat tillage tools on loosening of a clay soil

Very little research has been done to investigate soil loosening as a function of the geometry of the tillage tool and of the original soil properties and moisture content. A field experiment was conducted to observe the effects of the geometric parameters of flat tillage tools on their draft, cutting efficiency and loosening of a moist clay soil. The test tool variables included rake angles to the horizontal of 30, 60 and 90°, widths of 75 and 150 mm and depths of operation of 100, 150 and 200 mm. Measurements were taken of draft, disturbed soil cross sectional profiles and the initial area of soil disturbed by the tools. The resulting draft requirement increased with width, depth and rake angle of the tool. The cross sectional area of soil disturbed did not change appreciably with rake angle, but the significant increase in draft with angle resulted in markedly diminished soil cutting efficiency (area divided by draft). The degree of soil loosening was generally smaller at a rake angle of 60° than at 30 or 90°, and tended to be higher at greater depths of operation. In addition, a larger depth to width ratio generally increased the degree of loosening. Results for the soil studied indicate that the best implement design for low draft, high cutting efficiency and superior soil loosening should have a rake angle of about 30° and should be fairly narrow with a depth to width ratio of 2 or more.     

锯链连接片偏磨原因的受力分析及解决途径的研究

通过对国内外万能锯链负荷工作时的受力分析,发现现有万能锯链的切齿组件的设计几何参数不尽合理。因而,造成正压合力集中,促使连接片偏磨,缩短了锯链寿命。同时,偏磨后的切齿组件切削功能恶化,影响了链锯机械性能的发挥。为此,重新设计了切齿组件,使正压合力趋向多点均匀分布。经生产、台架试验证明,新型锯链的使用寿命,是国产锯链的2倍左右,是斯蒂尔锯链的1.5倍;切削效率比国产锯链提高35—116.7％,比奥利根锯链提高3—4％。同时,切齿组件在整个生产过程中,始终保持着良好的切削状态和原设计的主要几何参数。证明“正压合力多点均匀分布”的设计理论是克服连接片偏磨的可靠途径。     

接触轮式强力平面砂带磨削及其磨损试验研究

砂带磨损是影响加工精度、表面质量、加工效率和生产成本的重要因素之一。以往的研究只局限于普通砂带磨削的磨损，而强力砂带磨削磨损研究尚未见诸报导。本文对接触轮式强力平面砂带磨削的砂带磨损过程、砂带磨损形式、磨损机理及磨削参数对磨损的影响作了大量的实验研究。测定了此种磨削上的相对金属切除率、磨削法向力、磨削条件下砂带的金属去除机理和磨损机理，得出了一些重要结论。     

Infrared Thermography in Dogs with Mammary Tumors and Healthy Dogs

Background

Infrared thermography is a painless, noninvasive, nonionizing diagnostic imaging exam used in human medicine as an auxiliary tool for breast cancer diagnosis in women.

Hypothesis/Objectives

Define thermographic mean temperatures of healthy mammary glands and compare these temperatures with those of mammary glands with tumors in dogs.

Animals

Fifty client‐owned female dogs were evaluated, including 20 with histopathologically confirmed mammary tumor and 30 clinically healthy (control).

Methods

A randomized study using infrared thermography analyzed each mammary gland of the animals from the control group and mammary glands with tumors from the tumor group, then the thermographic temperatures obtained were compared. Thermographic exam was performed in a temperature‐controlled room with a cooled thermographic camera—Flir E‐40 (Flir Systems^®)

Results

There was significantly a higher temperature in the caudal abdominal and inguinal mammary glands than the other glands in the healthy group (P < .05). Dogs with mammary tumors had significantly higher thermographic temperature compared with unaffected glands regardless of the tumor size and the location (P < .05).

Conclusions and clinical importance

The technique seems to be able to assess for the presence of neoplasia within the mammary tissue in bitches. Further investigation is necessary to determine the impact of this technique when adopted clinically.     

Tooth length and incisal wear and growth in guinea pigs (Cavia porcellus) fed diets of different abrasiveness

Dental diseases are among the most important reasons for presenting guinea pigs (Cavia porcellus) and other rodents to veterinary clinics, but the aetiopathology of this disease complex is unclear. Clinicians tend to believe that the ever‐growing teeth of rabbits and rodents have a constant growth that needs to be worn down by the mastication of an appropriate diet. In this study, we tested the effect of four different pelleted diets of increasing abrasiveness [due to both internal (phytoliths) and external abrasives (sand)] or whole grass hay fed for 2 weeks each in random order to 16 guinea pigs on incisor growth and wear, and tooth length of incisors and cheek teeth. There was a positive correlation between wear and growth of incisors. Tooth lengths depended both on internal and external abrasives, but only upper incisors were additionally affected by the feeding of whole hay. Diet effects were most prominent in anterior cheek teeth, in particular M1 and m1. Cheek tooth angle did not become shallower with decreasing diet abrasiveness, suggesting that a lack of dietary abrasiveness does not cause the typical ‘bridge formation’ of anterior cheek teeth frequently observed in guinea pigs. The findings suggest that other factors than diet abrasiveness, such as mineral imbalances and in particular hereditary malocclusion, are more likely causes for dental problems observed in this species.     

刀具磨损过程的能力分析方法研究

将刀具磨损过程的总变异进行分解,共分为三部分：趋势项、残差自相关结构、未能解释的变异,以区分不同的变异来源,并计算出相应的能力指数.此方法有助于操作者更好地理解刀具磨损过程,确定降低过程变异的合理措施,同时也可使用该方法分析类似刀具磨损的自相关过程.     

O型圈农机传动滚子链的耐磨性研究

通过O形圈农机滚子链和普通滚子链的台架对比磨损试验，研究了两种链条的磨损机制，微观分析表明，对于锁轴和套筒铰链磨擦副而言，O形圈链条是以疲劳磨损为主，伴随着磨粒磨损；普通滚子链是以粘着磨损为主，伴随着磨粒磨损，对于O形圈和链板平面摩擦副而言，其磨损机制是以疲劳磨损为主。文中也指出了国产O形圈链条质量上存在的问题。     

仿生非光滑表面滑动摩擦磨损试验研究

采用激光处理技术加工了几种具有非光滑特征的圆形45号钢试件，以正交试验方法设计耐磨性试验方案。在国产MM200型摩擦磨损试验机上研究具有不同非光滑表面特征的试件耐磨性规律。试验结果表明，在相同试验条件下，时间、负荷、速度、形态和分布对耐磨性均有影响，耐磨性按照凹坑、凸包、波纹、鳞片形态递减。