On optical flow techniques applied to breaking surges

Surface wave breaking is a challenging two-phase flow process which plays an important role in numerous physical processes. A highly-turbulent unsteady breaking surge was investigated experimentally in a large facility, and substantial aeration occurred in the roller. The application of three optical flow techniques (Lucas-Kanade, Horn-Schunck and Farnback) to the air-water region was tested. The results indicated that the Farnback technique provided most accurate results, although some misleading results could be obtained near the air-water boundaries of the roller. The bore generation by a rapid gate closure showed a highly-unsteady complicated velocity field, with substantial free-surface deformations, wave breaking and formation of large coherent structures before the surge detached from the gate. Further upstream, the surge propagated as a hydraulic jump in translation and the data showed a marked shear region with a recirculation zone above, showing air-water flow features comparable to stationary hydraulic jumps. The upper and lower bounds of air-water flow region yielded data implying an air-to-water velocity ratio about 4–5 for a Froude number Fr₁ = 2.1.     

辊筒磨节能特性的探讨

众所周知，粉磨是水泥工业电耗的主要环节。升发新的粉磨设备，提高粉磨效率，一直是世界各国粉磨工作者所关注的大问题。以传统的球磨机为主的粉磨作业耗电量约占水泥厂总耗电量的65％～76％，能耗高，物料在磨内的停留时间长、噪声大。     

含气量对碾压混凝土抗冻性的影响

试验研究了含气量对碾压混凝土抗冻性的影响。研究结果表明：碾压混凝土抗冻耐久性的最佳含气量为５％。其结果可供今后碾压混凝土配合比设计时参考。     

A new strength test for ceramic cylinders—The Notched Roller Test

A new tensile strength test for ceramic rollers (cylinders) is presented, following the idea of the previously published and since that time standardized notched ball test. The specimen is prepared by cutting a long narrow notch along the symmetry plane of the roller, perpendicular to the end faces. By applying compressive forces perpendicular to the notch, tensile stresses are induced in the outer surface region of the roller opposite to the notch, mainly pointing in tangential direction with respect to the roller axis. The stress amplitude is proportional to the applied force and depends also on the test geometry and the Poisson’ ratio, which has been analyzed carefully with FE methods.Strength tests have been performed on two different qualities of commercial silicon nitride rollers of 10 mm diameter and length. According to their specification a significant difference in the strength has been obtained.     

Mechanical properties of roller compacted concrete containing rice husk ash with original and recycled asphalt pavement material

This study focused on the effects of rice husk ash (RHA) on the mechanical properties of roller compacted concrete (RCC) designed with original and reclaimed asphalt pavement (RAP) materials. The RCC mixes were produced by partial substitution of cement with RHA at varying amounts of 3% and 5%. Four aggregate combinations including the mix with original aggregate, coarse RAP + fine original aggregate, coarse original aggregate + fine RAP and total RAP were considered. The main experimental design consisted of the compressive strength and three points bending tests. Bending test was used to measure the modulus of rupture, material’s energy absorbency and analyse the fatigue response of RCC mixes. All tests were performed after 7, 28 and 120 days curing except the fatigue test that performed on 120 days specimens. Adding RHA resulted in higher optimum moisture content (OMC) and lower maximum dry density. Furthermore, adding RAP with different dimensions reduced the OMC and maximum dry density. The material’s flexibility improved upon replacing 3% cement by RHA. However, the energy absorbency reduced by increasing the RHA content to 5%. The fatigue life of RCC mixes containing RAP material was lower than the conventional one. Furthermore, replacing the coarse aggregate by RAP led to higher fatigue life than the fine aggregate. There was a strong relationship (R² > 0.90) between the energy absorbency and fatigue response of RCC mixes. At higher stress ratios of 0.72, the mix with higher energy absorbency behaved better under repeated loadings. Besides, a reverse relationship was found between the fatigue life and material porosity. Adding 3% RHA reduced the porosity especially after 120 days curing and improved the fatigue resistance. However, the addition of RHA to 5% resulted in higher porosities and lower fatigue lives.     

核电厂离堆放射性废物处理中心辊道控制

辊道作为核电厂放射性固体废物流转的核心设备, 承担着装有各种固体废物的废物桶的转运工作, 其可靠性、稳定性和安全性关系着固废处理生产线的正常运作。本文介绍了某核电厂离堆放射性废物处理中心辊道控制系统的功能、组成、流程及其改进方案, 以实现废物桶全自动化转运, 避免操作人员过多的受到辐射照射, 保证作业过程的安全和高效。     

降低中厚板辊底式热处理炉能耗的生产实践

针对中厚板辊底式热处理炉能耗较大、热效率偏低的情况,分析其产生原因。结合现场实际,讲述了改进的方法和过程,在使用中效果良好。     

不同粉磨方式对水泥相关特性影响的研究

采用同一种熟料,通过辊压机终粉磨、辊压机-球磨机联合粉磨和单独球磨三种粉磨方式,研究了水泥颗粒特性,探讨了颗粒特性对水泥物理力学性能的具体影响。试验发现,辊压机终粉磨水泥存在一定的颗粒缺陷,致使水泥的需水性增大和早期水化不良;球磨机粉磨水泥颗粒性能和早强发挥均较优,但其粉磨效率低、能耗高的问题明显;联合粉磨工艺粉磨效率高,水泥颗粒特性和物理力学性能也得到了明显改善。     

连铸零段辊系列磨损的研究

通过冶金连铸现场工况和使用要求的调查分析,并结合生产过程中发生不可控事故的研究,阐述了冶金连铸辊列第一段位工作状态的复杂性及其须具备的制造性能。     

基于多刀铣削过程的弧面分度凸轮建模方法

通过CAD软件的二次开发技术模拟多个铣刀同时铣削弧面分度凸轮的加工过程,给出一种孤面分度凸轮计算机辅助设计的建模方法.实例证明该种方法是正确可行的,并且大大简化弧面分度凸轮的建模过程,同时为建立复杂工作轮廓曲面凸轮的通用CAD系统提供依据.