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991.
毛明智 《中国制造业信息化》1999,(3)
运用机械可靠性设计理论与机械优化设计理论,提出了一个通用的二级斜齿圆柱齿轮减速机的概率可靠性优化设计数学模型,并对实例进行了计算,所得结果符合实际。 相似文献
992.
993.
以100t单孔底吹氩钢包为原型,应用三维连续性方程、动量N-S方程及湍流κ-ε双方程模拟了底吹氩过程中钢包内的钢液流动状态。利用Mixture多相流模型对单孔吹氩(0~700 L/min)过程进行数值模拟,对比分析插入直径691.05 mm,深650 mmn浸渍管前后钢包内的流动状态和钢液表面的卷渣。结果表明,无浸渍管时,临界卷渣吹气量为102 L/min,插入浸渍管后,临界卷渣吹气量增大到217 L/min。插入浸渍圆筒可以在增加吹氩量的条件下提高钢液搅拌效果,加速钢液混匀。 相似文献
994.
Christianne Mulat Marc Donias Pierre Baylou Gérard Vignoles Christian Germain 《Signal, Image and Video Processing》2008,2(1):51-58
This paper introduces low-level operators in the context of detecting cylindrical axis in 3D images. Knowing the axis of a
cylinder is particularly useful since its location, length and curvature derive from this knowledge. This paper introduces
a new gradient-based optimal operator dedicated to accurate estimation of the direction toward the axis. The operator relies
on Finite Impulse Response filters. The approach is presented first in a 2D context, thus providing optimal gradient masks
for locating the center of circular objects. Then, a 3D extension is provided, allowing the exact estimation of the orientation
toward the axis of cylindrical objects when this axis coincides with one of the mask reference axes. Applied to more general
cylinders and to noisy data, the operator still provides accurate estimation and outperforms classical gradient operators. 相似文献
995.
996.
Surface groove width is of great significance to the performance of the cylinder liner–piston ring (CLPR) with the different surface textures in marine diesel. However, little is understood about the specific application (e.g., the geometric parameters of surface textures and operating conditions) of surface texture in actual marine diesel engines. To address this issue, different surface groove textures including grooves structures with 1-, 2-, 3-, and 4-mm widths were designed based on previous results related to marine diesel engine applications. A series of experimental tests was conducted in a reciprocation tester, and data on the friction characteristics were obtained under different operating conditions. Comparative studies on the friction coefficients, worn surface features, and oil film characteristics were performed. Results showed that the 2-mm groove structure of the cylinder liner was more favorable for improving the wear performances at low speed, whereas a 3-mm groove structure of the cylinder liner was more suitable for improving the wear performance at higher speeds, though its wear performance needs to be improved under high load. These results help to understand the specific application of surface texture on the wear performance of the CLPR pair. 相似文献
997.
在对圆筒谐振子的数学模型计算和有限元分析的基础上,设计了一种新型的谐振式液体密度传感器.该传感器由双端固定的圆筒谐振子、自动增益和相位调节的测量控制电路、C8051F020单片机的信号处理系统组成,具有对压力变化不敏感和智能温度补偿的功能.实验结果表明,20℃时传感器系数为K0=-129.5668 kg/m3,K1=-0.253 5×106(kg/m3)/s,K2=0.623 9×1010 (kg/m3)/s2,在700~900 kg/m3的测量范围内,综合测量精度为0.1%. 相似文献
998.
介绍了一种缸筒内孔加工方法,它在精镗内孔完成后,再对缸筒内孔进行滚压,其粗镗、精镗和滚压均在采用普通车床改装制成的专用机床上进行。这种缸筒内孔的加工方法与现有技术相比,可解决现有缸筒内孔废品率高、加工成本高的问题。 相似文献
999.
Buomsik ShinYoungsoo Cho Daeha HanSoonho Song Kwang Min Chun 《International Journal of Hydrogen Energy》2011,36(20):13158-13170
The distinctive properties of hydrogen have initiated considerable applied research related to the internal combustion engine. Recently, it has been reported that NOx emissions were reduced by using hydrogen in a diesel engine at low temperature and heavy EGR conditions. As the continuing study, cylinder pressure was also investigated to determine the combustion characteristics and their relationship to NOx emissions. The test engine was operated at constant speed and fixed diesel fuel injection rate (1500 rpm, 2.5 kg/h). Diesel fuel was injected in a split pattern into a 2-L diesel engine. The cylinder pressure was measured for different hydrogen flow rates and EGR ratios. The intake manifold temperature was controlled to be the same to avoid the gas intake temperature variations under the widely differing levels (2%-31%) of EGR. The measured cylinder pressure was analyzed for characteristic combustion values, such as mass burn fraction and combustion duration.The rising crank angle of the heat release rate was unaffected by the presence of hydrogen. However, supplying hydrogen extended the main combustion duration. This longer main combustion duration was particularly noticeable at the heavy EGR condition. It correlated well with the reduced NOx emissions. 相似文献
1000.
In this paper a general weight function was derived to evaluate the thermal stress intensity factors of a circumferential crack in cylinders. The weight function derived is valid for a wide range of thin- to thick-walled cylinders and relative crack depth. Closed-form stress intensity factor based on the weight function method was derived as a function of the Biot number and relative depth and various inner-to-outer radius ratios of cylinders. The accuracy of the analysis has been examined using the finite element method results and were compared to existing solutions for uniform loading in the literature for special geometries, indicating an excellent agreement. 相似文献