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31.
分析了摩托车变速器三销齿轮的成形工艺。采用了高速令镦挤成形工艺,可提高三销齿轮的质量、减少机械加工及降低产品成本。对三销齿轮成形工艺和模具设计作了详细探讨。 相似文献
32.
一种新型的机械除尘技术——旋流除尘离心机 总被引:7,自引:0,他引:7
简要介绍了一项高效、经济的机械除尘技术,一种新型的旋流除尘离心机,给出了这种离心机除尘性能指标等的中期试验结果,指出了它的技术特点。 相似文献
33.
主要阐述带尾钉素阳极帽的结构特性.进行工艺设计,确定其工艺参数,以替代进口产品,实现国内生产,为国家和企业创造效益. 相似文献
34.
目的 齿轮产生故障时,利用其声发射信号进行自适应特征提取后诊断。方法 利用变分模态分解方法(VMD)对齿轮发生故障时的声发射信号进行分解。在现实状况中,采集声发射原信号噪声干扰大,导致特征提取准确度低,并且模态分解时参数需要人为调试设定。鉴于此,引入灰狼优化算法(GWO),对模态分解个数k和二次惩罚因子α自适应选择最优参数后,对信号分解得到本征模态函数(IMF)。通过相关系数选出最佳IMF作为特征分量,计算其峭度和样本熵。结果 计算了各分量的相关系数,选取与原始信号最为相近的分量,分别计算其峭度和样本熵。分解后,齿轮故障声发射信号峭度高于正常的情况,而样本熵则偶然性表现为正常情况下的值大于故障条件下的值。结论 采用支持向量机对特征向量集进行分类识别,对比改进后的试验结果,GWO-VMD结合峭度–样本熵的方法能够有效地提取故障特征,判断齿轮状态是否健康。 相似文献
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Bio-economic evaluation of implementing trawl fishing gear with different selectivity 总被引:1,自引:0,他引:1
Lone Grnbk Kronbak J. Rasmus Nielsen Ole A. Jrgensen Niels Vestergaard 《Journal of environmental management》2009,90(11):3665-3674
The paper develops a biological-economic evaluation tool to analyse the consequences for trawl fishers of implementing more selective fishing technologies. This is done by merging a dynamic biological population model and an economic cost–benefit evaluation framework to describe the consequences for the fish stocks, fishermen and society. The bio-economic evaluation is applied to the case of the Danish trawl fishery in Kattegat and Skagerrak, which experiences a high level of discards and bycatches of several species. Four different kinds of selectivity scenarios are evaluated in comparison with a baseline. The results from the evaluation are indicators for the consequences on ecological and economic levels. The results show that implementation of different selective fishing gear in the Kattegat and Skagerrak mixed trawl fisheries generally implies a trade off over time between rebuilding the stocks and economic loss. Moreover, the analysis shows that implementation of more selective gear is not always beneficial. 相似文献
38.
Stephanie J. Tuttle Author Vitae Author Vitae Mary Lynn Buonarosa Author Vitae 《Journal of Safety Research》2009,40(3):191-415
Introduction
This study compared the conspicuity of three types of first-responder safety garments (NFPA 1971-2007 turnout gear coats, and ANSI/ISEA 107 and 207 safety vests).Method
Participants drove instrumented vehicles on a closed track during both daytime and nighttime, indicating when they could first detect pedestrians in a simulated emergency response scene. Pedestrians wore one of the safety garments and stood on either side of the emergency scene, facing or perpendicular to oncoming traffic, and either stationary or walking in place.Results
All three garment standards provided equal levels of conspicuity, in that the distances at which the pedestrians were detected were equivalent. Time of day was a significant factor, with longer mean detection distances being observed in daytime. Pedestrian orientation was significant, with mean detection distances being longest when facing traffic. Pedestrian motion did not result in significant differences in detection distance.Discussion
The results suggest that all three garment types studied are equivalent in making first responders conspicuous as pedestrians when working an emergency response scene in close proximity to traffic.Impact on Industry
Whether an NFPA or ANSI/ISEA compliant is worn, first responders are equally likely to be detected by passing motorists, and as such these garments should be considered to be equivalent. 相似文献39.
Lawrence J.H. Schulze Edward Stanton Anupam Patel Maurizio Cheli 《International journal of occupational safety and ergonomics》2013,19(1-2):31-40
Hand cranks are used in a variety of industries to actuate valves and in other gear-operated applications. In order to evaluate these types of operations and their compatibility with operator strength capabilities, a rotational dynamometer was used to measure torque production capability of operators using a hand crank at different heights and angles (with respect to the coronal plane). The tests were conducted for both clockwise and counterclockwise rotations using the dominant arm of each test participant. A total of 18 tests were completed by each of five male right-handed test participants. A 0° declination angle, counterclockwise operation, and both 40.65 cm and 60.96 cm heights were found to be associated with the greatest torque production capabilities. 相似文献
40.
《International Journal of Sustainable Engineering》2013,6(4):326-331
A bio-based gear oil was developed from soybean oil (SBO). The SBO was first thermally polymerised and then mixed with additives and diluents. The effect of pour point depressants, co-base oils, antioxidants and anti-wear additives is reported. Lubricity, viscosity index and oxidation stability of the final formulation of the bio-based gear oil are compared with commercially available gear oils. The final formulation of bio-based gear oil gives test results: viscosity index 165, four-ball wear scar 0.375 mm. These numbers are comparable to or better than the commercially available gear oils tested for comparison. The oxidation onset temperature of the bio-based gear oil, 220°C, is lower than the evaluated commercial products, but still at an acceptable range for gear oil. 相似文献