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战时陆军防空兵车辆装备抢修作业是迅速恢复陆军防空兵机动能力的重要手段,其作业能力的大小直接影响陆军防空兵伴随防空作战效能,因此,应高度关注其车辆装备抢修工作,对其进行客观、定量的评估。对防空作战单元机动效能指数的确立提出修正意见,可为提高陆军防空兵伴随防空作战能力提供参考。 相似文献
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明月峡长江大桥建成后,桥下左岸洪庙角礁石将影响该滩段航道尺度的进一步提高。为避免这一情况,针对其河势及滩情,考虑长江航运远期发展的需求,在原3. 7 m炸礁方案的基础上提出了加深炸除方案。采用平面二维数学模型对此方案进行论证研究,并用实测水面线和流速分布验证该模型,结果表明模型验证较好、可正确模拟该滩段实际水流运动。方案实施后,设计最低通航水位的断面平均流速及沿程流速变化均小于0. 01 ms;沿程比降没有明显变化,仅在炸礁区域上游水面略有下降,最大约0. 01 m;炸礁区流场改善明显,流向与航槽夹角显著减小,改善了船舶的航行条件。 相似文献
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选择醇酸、丙烯酸、聚氨酯和氟碳4类涂料进行对比试验,研究其耐紫外、耐湿热和耐碱溶液的性能。试验结果表明:醇酸涂层和丙烯酸涂层整体耐老化性能较差,湿热老化处理7 d后,试件的失光率高达90%以上,表面出现严重的开裂和起泡现象。聚氨酯涂层耐碱溶液的性能较好,但是受紫外老化和湿热老化影响较大,其紫外老化28 d后失光率大于75%,拉伸强度和断裂伸长率下降超过40%,湿热老化7 d后的失光率达97%,表面开裂和起泡情况严重。氟碳涂层耐老化性能优异,老化28 d后失光率不到20%,表面无粉化、开裂、起泡、剥落等现象,拉伸性能未受损害。4类涂层耐老化性能的顺序为醇酸涂层<丙烯酸涂层<聚氨酯涂层<氟碳涂层。 相似文献
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In order to obtain the present effective prestress and its longitudinal distribution of prestressed tendon during the process of inspection and evaluation, a unified analogue method was put forward. Based on the theory for calculating instantaneous prestress loss of the tendons with complicated geometry, a universal numerical model was established. Therefore, the distribution of effective prestress could be simulated after recognizing the nominal coefficients of prestress loss with the obtained stress data of objective steel tendon. The numerical simulation results of a full-length tendon of a three-span continuous beam bridge show that the relative errors between the calculated value and the value in the code are within 5%, which meets the requirement for engineering application. 相似文献
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