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兰清生 《中国特种设备安全》2014,(10):42-44
利用曝光曲线和胶片特性曲线,推导了焊缝内部体积缺陷高度的计算公式,缺陷高度计算公式适应于焊缝表面比较平滑的体积型缺陷计算。通过测量缺陷处底片黑度、缺陷附近焊缝处底片黑度、缺陷附近母材处底片黑度、缺陷附近焊缝高度,可以用公式计算焊缝内部体积缺陷高度,该公式能够应用于未焊透和条状夹渣的高度测定,并在压力容器定期检验时对未焊透和条状夹渣缺陷安全状况进行定级。 相似文献
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通过对TSP、SO2浓度在不同高度实测研究.得出平顶山市SO2在1.5m至20m不同高度监测,高度影响无显著性差异;TSP在5m至15m不同高度监测,高度影响无显著性差异。 相似文献
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The objective of this work is to investigate the horizontal stretching effect of ground on high-pressure vapor jet of LNG tank leakage near the ground. A numerical model for leakage jet was developed and several series of leakage scenarios were theoretically analyzed for different heights of the tank orifice, inner pressures and outer temperatures. The results show that the near ground plays an important role in the horizontal transportation of LNG leakage vapor. The corresponding danger distance is surprisingly lengthened because of the horizontal stretching of leakage vapor cloud by the ground nearby, especially for those cases with a lower orifice on tank. It is illustrated that there is an obvious change for the central axis track, gas concentration and velocity of the jet in the far-field during the jet is touching the ground. In addition, the dimensionless analyses on the dependence of gas concentration, velocity and gas concentration on the transportation distance indicated that there were two stages of deflection behaviors of the jet. Finally, the enlarged danger distance by the horizontal stretching for the LNG tank leakage with a low orifice indicated the more dangerous scene of those leakage close on ground. The data and revelation here about the danger area prediction can be an important guide for the emergency management during the LNG tank leakage accidents. 相似文献
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up-BAF同步硝化反硝化工艺去除污染物的机理研究 总被引:4,自引:0,他引:4
阐述了同步硝化反硝化的原理,研究了上向流曝气生物滤池(up—BAF)同步硝化反硝化工艺对城市生活污水的处理效果及规律。研究结果表明,同步硝化反硝化工艺对COD、NH3-N的去除率随填料高度的增加而增加,最下层50cm厚滤料去除污染物的效果最好,该工艺脱氮效果不理想,TN去除率只有30%左右。当水力负荷在2.39m/h以下时,水力负荷对COD、NH3-N去除的影响较小。 相似文献
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Potential mechanisms for the communication of height and distance by a stingless bee, Melipona panamica 总被引:1,自引:1,他引:0
This study investigates the recruitment communication mechanisms of a stingless bee, Melipona panamica, whose foragers can evidently communicate the three-dimensional location of a good food source. To determine if the bees
communicate location information inside or outside the nest, we conducted removal experiments by training marked foragers
to one of two identical feeders and then separating these experienced foragers from potential recruits as they left the nest.
The feeders were positioned to test the communication of each dimension. The results show that recruits do not simply follow
experienced foragers to the food source. Height and distance are communicated within the nest, while direction is communicated
outside the nest. We then examined the pulsed sounds produced by recruiting foragers. While unloading food, recruiting foragers
produced several short pulses and one or more very long pulses. On average, the longest unloading pulse per performance was
31–50% longer (P ≤ 0.018) for bees foraging on the forest floor than for bees foraging at the top of the forest canopy (40 m high). While
dancing, recruiting foragers produced sound pulses whose duration was positively correlated with the distance to the food
source (P < 0.001). Dancing recruiters also produced several short sound pulses followed by one or more long pulses. The longest dance
pulse per performance was 291 ± 194 ms for a feeder 25 m from the nest and 1858 ± 923 ms for a feeder 360 m away from the
nest. The mechanism of directional communication remains a mystery. However, the direction removal experiment demonstrates
that newcomers cannot use forager-deposited scent marks for long-distance orientation (>100 m from the nest).
Received: 25 September 1997 / Accepted after revision: 31 May 1998 相似文献
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利用控制苯标准气峰高精密度的方法,达到日常用气相色谱法对空气中苯浓度监测质量控制的目的. 相似文献
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This paper studies the long-term effects of high temperatures during pregnancy on later-life outcomes for Chinese adults. Adults experienced one additional high-temperature day during in utero period, on average, attain 0.02 fewer years of schooling, increase the risk of illiteracy by 0.18%, achieve lower standardized word-test score by 0.48%, and are shorter by 0.02 cm. The impacts are greater in the first and second trimesters. Additionally, we find that income effects represent one important channel to explain the adverse effects of hot weather. Back-of-the-envelope predictions suggest that by the end of the 21st century, a 0.14–0.54 reduction in years of education and a 0.21–0.84 cm reduction in height is likely to result from climate change, ceteris paribus. 相似文献
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