共查询到19条相似文献,搜索用时 357 毫秒
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包钢为了提高250 km/h钢轨的合格率,通过对影响钢轨合格率的主要因素进行分析,确定是轧疤、轧痕等表面缺陷,通过现场跟踪,判断出250 km/h钢轨表面轧疤、轧痕缺陷产生的位置,针对不同位置采取不同措施,同时,将这些轧疤、轧痕缺陷进行归纳总结,纳入生产管理,从而有效地控制了轧疤、轧痕缺陷,因而,随着表面缺陷的减少,250 km/h钢轨的合格率得到了大幅度提升,从而保证了250 km/h钢轨满足高速铁路用轨的要求。 相似文献
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为了准确掌握冷轧钢卷经过各工序时的缺陷位置,查找缺陷产生的机组和原因,研发了钢卷缺陷位置判定技术。通过从后往前推算钢卷缺陷所在的表面位置、长度位置、宽度位置,定位缺陷发生的机组和具体位置。该技术的应用为分析缺陷产生原因、降低钢卷缺陷发生率、减少批次质量事故起到重要辅助作用。 相似文献
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介绍了IF带钢退火后表面出现的条状白斑缺陷、位置分布、缺陷部位,对缺陷的微观形貌和成分进行了分析。结合各工序跟踪及工艺条件状况,认为IF带钢表面白斑缺陷产生源头为热轧工序的氧化铁皮压入,确定了该缺陷的产生原因;提出增开机架间冷却水的改进措施,杜绝了IF钢白斑缺陷在生产过程中的出现,提高了产品质量。 相似文献
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针对生产过程中出现的连铸钢坯表面裂纹缺陷,采用图像检测与小波分析方法模仿人工视觉对连铸钢坏表面图像信号进行模式识别检测。 相似文献
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This paper presents both numerical and experimental studies of the transient response of concrete I-girders with and without flaws subjected to transverse elastic point impact. These studies were aimed at evaluating the capability of using the impact-echo method for integrity testing of concrete I-girders. Numerical and experimental studies were performed first to gain an understanding of transient stress wave propagation in solid I-girder segments. Experimental studies were carried out on full-size reinforced-concrete I-girder segments containing flaws at known locations. Results obtained from these studies show that the transient response of a solid I-girder subjected to impact on the bottom surface is composed of a number of resonant frequencies caused by cross-sectional modes of vibration. Among these frequencies there is a predominant frequency, and its value depends on the cross-sectional geometry and dimensions of the bottom portion of the I-girder for a given P-wave speed in concrete. It is also shown that the presence of a flaw disrupts the modes of vibration. A shift of the predominant frequency to a lower value is a key indication of the presence of the flaw. In addition, multiple wave reflections between the impact surface and the surface of the flaw produce a large amplitude peak in the spectrum at the frequency corresponding to the depth of the flaw, and thus make it easy to locate the flaw. 相似文献
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介绍了天津钢管公司能源部冷却水处理自动控制系统,阐述了PLC系统在水处理工艺应用过程中存在的缺陷和完善的方法. 相似文献
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Prior studies on the time-of-flight diffraction (TOFD) method have focused primarily on ground smooth, clean surfaces of steel. In practice, however, the surface of an existing bridge element will be covered with rust or have several layers of paint. The main objective of this study was to evaluate the influence of the surface condition of steel elements (i.e., painted or rusted) on the ability of the method to accurately detect and size flaws. These objectives were met by performing a number of tests on plates with saw cuts or implanted fatigue cracks with different surface conditions. These included ground smooth and polished, rusted, and painted surfaces. The data show that rusted surfaces will reduce the amplitude of the ultrasonic signals, but they will not impair the ability of the TOFD method to detect and accurately size flaws. A painted surface will also cause a reduction in signal amplitude. More important, however, is the appearance of additional wave signals that could be interpreted as false indications. While these additional signals do not obscure the presence of actual flaws or affect the accuracy of the TOFD method to size the flaws, they make flaw detection more difficult. Based on the results of this study, recommendations for field inspection on rusted or painted surfaces using the TOFD method are provided. 相似文献
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Horne Murray R.; Martin Gerard M.; Harley Carolyn W.; Skinner Darlene M. 《Canadian Metallurgical Quarterly》2007,33(2):92
Place learning is impaired when a single plus maze is moved between adjacent locations 33-120 cm apart. This maze translation creates distinct start locations but maintains a single goal location with respect to distal cues. Hippocampal cell recording data suggest the majority of place fields are tied to apparatus boundaries, not to distal cues, when an apparatus is moved these distances to the left or right. Thus, rats may fail to appreciate the existence of multiple start locations with respect to distal cues when the maze is moved in this way and their start location on the surface is constant. Performance on the single plus maze problem was improved when texture cues were correlated with different start locations. Place learning was supported when multiple start locations were provided on a single large surface (double plus maze), even though rats did not explore the entire surface. Place learning was also supported when random extensions were added to a double plus maze such that start locations, relative to surface boundaries, were not informative as to goal location. This outcome suggests sensitivity to multiple start locations is required for distal cue use in translational place problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献