一种潜艇装备作战能力比较研究方法     

罗浩  宁云晖  陶伟  尤岳 《数字海洋与水下攻防》2020,3(6):494-498

对潜艇装备作战能力评估问题进行了研究，发现运用定量评估方法的过程中存在指标评价所需数据无法完全获取的问题。结合美弗吉尼亚潜艇改进情况，分析了影响潜艇作战能力的一些关键因素，重点基于潜艇武器装载能力，对国外典型潜艇进行了作战能力比较分析，最后对分析结果进行了评价，并讨论了未来潜艇作战能力评估方法的发展方向。  相似文献   

居住迁移对居民健康的影响研究进展述评     

程晗蓓  邹游  林赛南  李志刚 《地理科学进展》2020,39(7):1210-1223

进入城市时代以来,居住环境与居民健康的联系愈发密切,尤其在“流动性"增强的大背景下,居住迁移对居民健康的影响问题受到广泛关注。论文结合知识图谱分析和文献研究法,系统评述居住迁移影响居民健康问题的最新进展。研究发现：① 近15 a来,该领域的文献数量逐年增多,关注度持续上升;文献空间分布主要集中在发达国家,但不同地区的研究内容存在显著差异。② 主要研究对象由“同质性群体”向“异质性群体”转变,从“一般性群体”向“特殊群体”转变;研究方法由数理统计向混合研究、综合应用转变。③ 研究视角经历“人口迁移—个体健康”“居住迁移—环境—个体健康”与“迁居轨迹—环境演变—个体健康发展”等3个演变阶段。④ 近期研究重点有：迁居行为与儿童健康,迁居时空特征与身心健康,住房生涯与身心健康,邻里环境、累积剥夺与健康发展等。结合以上分析,提出如下建议：注重“整合性”分析;关注城市内部迁居行为和多次迁居轨迹对居民健康的影响;扩大迁居引发的“环境”因素(如居住隔离、社会分异、职住空间错位等)研究;更多关注迁居对二代流动人口儿童健康的影响,侧重对非正规居住空间如“城中村”等的研究。  相似文献   

A modified numerical model for moisture-salt transport in unsaturated sandy soil under evaporation     

Wei Wen  YuanMing Lai  ZheMin You 《寒旱区科学》2020,12(3):125-133

Soil salinization, caused by salt migration and accumulation underneath the soil surface, will corrode structures. To analyze the moisture-salt migration and salt precipitation in soil under evaporation conditions, a mathematical model consisting of a series of theoretical equations is briefly presented. The filling effect of precipitated salts on tortuosity factor and evaporation rate are taken into account in relevant equations. Besides, a transition equation to link the solute transport equation before and after salt precipitation is proposed. Meanwhile, a new relative humidity equation deduced from Pitzer ions model is used to modify the vapor transport flux equation. The results show that the calculated values are in good agreement with the published experimental data, especially for the simulation of volume water content and evaporation rate of Toyoura sand, which confirm the reliability and applicability of the proposed model.  相似文献   

福建政和县东际金（银）矿床黄铁矿微量元素和硫-铅同位素及锆石年龄研究     

肖凡  班宜忠  范飞鹏  许乃岑  毛光武  李凤春 《中国地质》2020,47(2):375-393

东际金(银)矿床赋存于燕山晚期南园组火山岩中,是东南沿海地区一个隐爆角砾岩型贵金属矿床,已探明金资源量达12.5 t,银资源量135.9 t。通过开展主要金属硫化物黄铁矿电子探针和硫-铅同位素分析,讨论了成矿作用和成矿物质来源等问题。研究表明,东际金(银)矿床黄铁矿Co/Ni值3～94(平均值23)且Co含量为500×10-6～1070×10-6(均值799×10-6),Fe/(S+As)值0.827～0.871(均值0.860),Au/Ag值0.9～5.5(均值2.6),反映该矿床是与陆相火山作用有关的浅成中低温热液型矿床。黄铁矿δ34S在-6.6‰～-0.7‰,206Pb/204Pb为17.9801～18.4303,207Pb/204Pb为15.2689～15.9397,208Pb/204Pb为37.9052～38.7871,指示成矿物质主要来源于具有壳幔混源性质的花岗质岩浆,此外含矿热液也活化萃取了部分基底变质岩和火山岩围岩的金属元素。通过锆石U-Pb年代学研究和区域成矿资料对比,东际金(银)矿床成矿时代可被限定于早白垩世晚期。  相似文献   

结合图像增强和恢复的增强现实跟踪注册     

郭士祥  范铀  范冲 《测绘通报》2020,(8):39

增强现实中的跟踪注册技术一直是研究的重点和难点，而地下矿道和巷道内亮度低，产生的图像较昏暗，车载相机快速运动和抖动，对传统的基于特征匹配的跟踪注册提出了挑战。本文从提高增强现实中跟踪注册稳健性和精度出发，采用基于Retinex改进的方法增强昏暗图像的亮度，同时利用基于对抗神经网络的方法恢复运动模糊图像。首先提取图像ORB特征，实现初始化；然后根据跟踪特征点的数量，开启图像增强和图像恢复线程，提高特征点提取质量和数量。在数据集和真实模拟场景下的试验结果显示，跟踪精度提高了12%左右，在低亮度和含有轻微模糊的情况下，跟踪注册稳健性也有显著提高。  相似文献   

Application of Ultra-shallow Seismic Survey to the Wanggezhuang Fault in Qingdao     

Yang Qiyan  You Huichuan  Di Long 《中国地震研究》2018,32(4):574-583

At present, there is less theoretical research and practical experience in the aspect of ultra-shallow seismic exploration to the target layers at depths of only tens of meters both at home and abroad. Seismic exploration plays an important role in the location of faults and active structures, but the depth dozens of meters below the ground surface is the blind area of any kind of deep and shallow seismic exploration. Starting from the point of view of detecting urban active faults, and using related theories and methods of geology, geophysics and mathematics, the paper discusses the preconditions for acquiring efficient ultra-shallow seismic survey results in complicated geological backgrounds in Qingdao. Taking the Qingdao area as an example in this paper, we study the depth condition of Quaternary deposits, and apply 4-8 stacking folds to satisfy the requirement to get the exploration results with high-resolution and high-SNR. Preliminary results reveal that selecting a proper surveillance layout is one of the keys to acquire authentic exploration results in ultra-shallow P-wave reflection exploration. Our results also show that ultra-shallow seismic reflection method in detecting faults in the Qingdao area has good application prospects.  相似文献   

电阻率成像及浅层地震勘探在控盆构造探测中的应用——以万全断裂为例     

周月玲  尤惠川  温超  王燕 《地震地磁观测与研究》2018,39(2):62-69

万全断裂是洋河盆地北缘断裂带组成断裂之一，控制沿线构造活动及地貌发育。断裂走向NE，倾向SE，在沟口处隐伏于第四纪覆盖层，采用电阻率成像和浅层地震联合勘探方法，获得该断裂隐伏段落综合物探异常，结合地质地貌调查，判定隐伏段落展布的具体位置、产状、活动特征及地下结构特征等。研究结果表明，万全断裂隐伏段落走向NE，倾向SE，倾角约75°，上断点埋深约20 m，20—240 m深度可见断裂破碎带（宽约10—20 m）物探异常特征及断裂两侧地层结构差异。该联合探测模式可有效探测复杂地质构造条件下的隐伏活动断裂，具有较强实用性，值得推广。  相似文献   

Three-dimensional finite element analysis of laterally loaded bridge caisson foundations in gravelly soil     

Chiou  Jiunn-Shyang  You  Jia-Qi 《Acta Geotechnica》2020,15(11):3151-3166

Acta Geotechnica - In this paper, we propose a three-dimensional finite element model that can simulate the caisson foundation behavior in gravelly soil. The soil model adopts a combination of the...  相似文献   

Feeding intensity and molecular prey identification of the mantis shrimp,Oratosquilla oratoria (De Haan, 1844), in the Tianjin coastal zone of Bohai Bay     

Qi-Kang Bo  Yun-Zhao Lu  Hui-Jing Mi  Yan-Guang Yu  De-Xian Gu  Hong-Zheng You  Shuang Hao 《Marine Ecology》2020,41(4):e12594

Bohai Bay, a representative semi-enclosed bay of China, has been severely impacted in recent decades by rapid human development. Although the mantis shrimp Oratosquilla oratoria plays an important role in the Bohai Bay ecosystem and fishery, its feeding ecology and the impact of habitat changes on its feeding habits are poorly known. In this study, we sought to identify its feeding strategy through the separation of stomach contents, and to describe its trophic ecology during maturation in the Tianjin coastal zone of Bohai Bay by the DNA barcoding method using a fragment (about 690 bp) of the mitochondrial cytochrome oxidase I (CO I) gene. A total of 594 specimens were collected from March to July 2018, and 347 (58.42%) stomachs were found to have food remains. More than half of the O. oratoria individuals had poor feeding activity, and the degree of feeding of females was higher than that of males, but there was no significant difference in the visual fullness index and the fullness weight index (FWI) between sexes for each month. In addition, the feeding activity of O. oratoria was consistent across the months, suggesting in artificial breeding programs it is not worried too much about the accessional diet supplied to the female bloodstocks except maintaining their normal food. A total of 167 retrieved prey items yielded 187 readable sequences; 86.63% of these sequences could be assigned to the species level. Consequently, 25 different prey taxa covering all readable sequences were identified, showing O. oratoria is a generalist predator. In terms of percent composition by frequency of occurrences (%N), crustaceans and fishes accounted for the same and highest percentage (35.83%) in the mantis shrimp diet, followed by mollusks (24.59%) and the remaining marine organisms (3.73%) including Polychaeta (2.67%), Sagittoidea (0.53%), and Chromadorea (0.53%). The result shows the benthic fish Oxudercidae (family) appears to be an especially important food supply for O. oratoria during maturation. The degree of cannibalism decreased with an increase in diet species and the frequencies of cannibalism in this study was noticeably higher than that in previous studies, suggesting that cannibalism may be a significant feeding strategy in the mantis shrimp O. oratoria in the Tianjin coastal zone of Bohai Bay, and because of the frequently cannibalistic behavior, the high stocking density of broodstocks should be avoided.  相似文献   

大跨径桥梁挠度变形监测技术应用实践          下载免费PDF全文

孙丰春 《海洋测绘》2020,40(4):77-82

在大跨径桥梁的静载试验过程中,挠度是重要的技术参数,为确保挠度变形监测成果的可靠性,以某斜拉桥为例,综合应用精密水准测量法、连通管式挠度监测法和全站仪三角高程法,相互检核验证,分析评价内符合精度和外符合精度。结果显示,在封闭交通和温度相对恒定的环境下,几种方法的挠度监测结果均满足规范要求,但各有不足。由于受监测环境温度、车辆荷载、仪器自身精度等诸多因素制约,精密水准和连通管法结果较为接近,三角高程法则略有差异,应结合有限元模型和控制截面应力应变结果综合分析。3种方法相互检核,实现不同挠度测量方法的有益补充。  相似文献