壳体厚度对传爆药慢速烤燃响应的研究

针对传爆药在制造、存贮、运输及实战环境中可能会遭受意外的热刺激,本文通过壳体厚度对传爆药慢速烤燃响应特性的影响的实验研究,来检测弹药对意外刺激的敏感程度和发生反应时的剧烈程度,并对实验结果进行了分析。实验以钝化RDX为主装药,以45#钢为壳体,利用自行设计的慢速烤燃试验系统对其进行试验。结果表明：在相同装药条件下,随着壳体厚度的增加,单位时间内传热量减少,体系升温速率减慢,炸药的烤燃时间随之增加,热爆炸延滞期增长;同时,随着壳体厚度的增加传爆药发生慢速烤燃反应的温度升高,热敏感程度降低,热安定性也随之提高。另外,在相同装药条件下,壳体厚度对慢速烤燃响应的剧烈性也有很大得影响。烤燃反应的剧烈程度随着壳体厚度的增大而减小。     

基于GAN的小样本腐蚀失厚率数据增强方法

目的 对小样本腐蚀失厚率数据进行数据增强,实现数据扩充,以提升后续分析模型的预测精度,减轻过拟合程度,并提升模型的泛化能力。方法 利用生成对抗网络(Generative Adversarial Networks,GAN)扩充腐蚀失厚率数据,使数据分布更加全面。对生成数据进行降维可视化分析,探究生成数据与原始数据样本的分布规律,分析数据增强合理性,并从多个算法模型、多个评价指标角度对分析预测能力、泛化能力进行评估。结果 生成数据填补了原始数据在样本空间分布的薄弱环节,加入生成数据后,各机器学习算法模型得出的MSE均值为未加入生成数据的61.72%~91.74%,皮尔逊均值为99.01%~113.64%,预测准确度提升,结果关联性更强,模型泛化能力增强。结论 GAN能有效对小样本腐蚀失厚率数据进行增强,数据扩充对分析预测提供正向支持,生成数据不宜多于原始数据,防止扰乱训练样本分布,同时存在生成数据多样性受限的问题。     

1981~2017年四川省大气自净能力变化特征分析

利用四川省1981~2017年逐日地面气象观测资料和2017年1月环境监测资料,计算分析了四川省大气自净能力指数的时空变化特征及其影响因子,并初步探讨了2017年1月成都市大气自净能力指数与空气质量的关系.结果表明：四川省大气自净能力指数的分布形势以川西高原北部、川西高原南部、攀西地区、盆地西南部大气自净能力为较好到好,省内其余大部地区大气自净能力较差到差.近37a来,四川省、川西高原、攀西地区多年变化呈减弱趋势,四川盆地多年变化趋势不显著.影响因子中,四川省降水日平均大气自净能力指数小于非降水日.四川省以及各区域平均风速、通风量、风速较大日数和小风日数与大气自净能力指数呈显著正和负相关关系;混合层厚度与大气自净能力指数呈显著的正相关关系.     

The sonographic diagnosis of chorionicity

The differentiation between mono- and dichorionic placentation in twin pregnancies is of clinical importance because of the significant difference in perinatal morbidity and mortality between the two, and the increased surveillance indicated in monochorionic gestations. Application of ultrasonography has enabled very precise prenatal determination of chorionicity. While this is best performed in the first trimester when accuracy approaches 100%, even in the third trimester, using a composite cascade of available sonographic features, accuracy has been reported to approach 97%. While two clearly separate placentae or discordant fetal gender conform to dichorionicity, in most twin pregnancies other features need to be assessed to determine chorionicity. The presence of the ‘lambda’ or the ‘T’ sign in the presence of a single placenta, best determined in the first trimester, is the most reliable indicator of chorionicity, with measurements of the inter-twin membrane thickness and counting of the membrane layers being less reliable. In this article, we review the sonographic features that help in the accurate depiction of chorionicity. Copyright © 2005 John Wiley & Sons, Ltd.     

土层分层厚度对场地地表地震动参数的影响

以江淮地区典型场地资料为原型,选取不同的土层分层厚度,构造多种场地土层计算模型,选择Taft、Kobe和El Centro三条强震记录作为地震输入,采用一维频域等效线性化波动方法分析了分层厚度对场地地表地震动参数的影响。研究表明:土层分层厚度对场地地震动参数存在影响,主要表现为采用较大分层厚度计算得到的地表峰值加速度A_(max)和反应谱特征周期T_g相对偏低,应采用尽可能小的土层分层厚度;分别采用1.0m和2.0m分层厚度计算得到的地表加速度反应谱形状基本重合,A_(max)和T_g也基本一致,最小选取2.0m土层分层厚度可以满足工程精度的要求。     

保温层下管道腐蚀监测系统及应用研究

为预防保温层下管道腐蚀带来的严重问题,必须采取有效措施进行腐蚀在线监测,以了解管道的剩余壁厚情况。在分析现有的腐蚀监测技术不足的前提下,基于γ射线数字扫描检测技术（GSDT）,研发了1套保温层下管道腐蚀在线监测系统,该系统可以实现对保温层下腐蚀管道剩余壁厚在线监测,并通过带保温层管道的检测试验和t-分布分析方法检验腐蚀监测系统的检测精度,最后以某化工企业为例,验证了该系统的有效性。结果表明:腐蚀监测系统可以实现对保温层管道剩余壁厚的监测,保温层和高密度介质不影响管壁厚度的测量结果,且使用所研发的腐蚀监测系统监测到的管道腐蚀速率与现场实际腐蚀速率基本一致。     

某单井站场管道积液及腐蚀特性研究*

为应对湿天然气管道存在的明显积液,导致管材腐蚀,目前经验性的检测点选择方式导致检测成本和工作量过大问题。基于某单井站场工况条件和现场壁厚检测数据,针对站场主管线,采用Fluent软件建模分析管线内液相分布规律。结果表明:含液率大小随原料气含水量、流量、压力的变化而呈正相关变化,运用Correl函数对现场壁厚检测数据和模拟结果进行对比验证,发现两者的相关度达到0.61以上,这为现场合理选择腐蚀检测点提供依据,降低了现场检测工作量和检测成本。     

Spatial and Temporal Trends in Organochlorine Contamination and Bill Deformities in Double-Crested Cormorants (Phalacrocorax Auritus) from the Canadian Great Lakes

The levels of organochlorine contaminants (OCs) in the eggs of double-crested cormorants (Phalacrocorax auritus) from the Canadian Great Lakes, Lake Nipigon and Lake-of-the-Woods were monitored between 1970 and 1995. PCBs and p,p-DDE were present at the highest concentrations. Significant declines in OC concentrations on the Great Lakes were observed over this period for Lake Ontario, Lake Superior, Georgian Bay and North Channel but not Lake Erie where levels remained relatively stable. In the early 1970s, the greatest OC levels were generally observed in cormorant eggs from nesting sites in Georgian Bay and North Channel of Lake Huron. Between 1984 and 1995 mirex and PCB levels were consistently highest in samples from Lakes Ontario and Erie, respectively. Similar levels of PCDDs and PCDFs were observed from all regions of the Canadian Great Lakes in 1989. In general, OC levels in cormorant eggs between 1984-95 were ranked as follows: Lake Erie>Lake Ontario Lake Superior>Lake Huron. In 1995, eggshell thickness in Canadian Great Lakes cormorants, ranged from 0.423 to 0.440 mm and was on average only 2.3% thinner than pre-DDT era values. Between 1988 and 1996, 31 cormorant chicks with bill defects were observed at 16 different colonies (21% of all colonies surveyed) in Lakes Ontario and Superior, Georgian Bay and North Channel, and the main body of Lake Huron. No bill deformities were observed at reference sites in northwestern Ontario (Lake Nipigon and Lake-of-the-Woods). For the period 1988-96, the prevalence of bill defects in cormorant chicks (0.0 to 2.8/10,000 chicks) did not differ significantly (P > 0.05) among most regions in the Canadian Great Lakes. Georgian Bay was the only region to show a significant decrease in the prevalence of bill defects between the periods 1979-87 and 1988-95.     

我国早晨与傍晚的大气边界层厚度研究

首先探讨了常规气象资料计算大气边界层厚度的方法,然后利用全国１２５个无线电探空站的观测资料,计算了我国早晨与傍晚时的大气边界层厚度ｈ,并分析了ｈ的地区分布与季节变化特征。结果表明,华南地区边界层厚度年平均值最大（ｈ＞５００ｍ）;陕甘宁地区最小（ｈ＝３１８ｍ）;多数地区的ｈ值在冬季最小而夏季或春季最大。