汛期短历时强降水过程的闪电特征     

王秀玲  曹晓霞  朱靖民 《气象科技》2014,42(1):140-144

对2011年3次短历时强降水天气过程的闪电特征分析结果表明:①3次短时强降水都以负闪为主,负闪占总闪电的比例都在92﹪以上;②小时闪电频数峰值超前降雨峰值1h或同相;③5min闪电频数超前雨量峰值5~60min;④负闪电密集区主要发生在40dBZ以上的回波区,偶尔发生的正闪一般在较弱回波处;闪电大部分发生在回波顶高大于5km以上的区域;多分布在速度不均匀场附近;闪电密集区与VIL大值区对应关系不太好;⑤不同云体,闪电特征不尽相同,闪电频数高峰有的发生在强回波阶段,有的并不是回波最强阶段,而是减弱阶段。强回波前沿出现闪电密集区或前方无回波处发生闪电,预示未来强回波移动的方向;有的云体发展、成熟阶段闪电分布密集,负闪电主要集中在强回波中心附近,云体减弱阶段闪电分散,集中在单体的不同部位。  相似文献   

气象装备保障效能评估技术     

涂爱琴  黄磊  苏莉莉  郭海涛  陈庆亮 《气象科技》2014,42(6):997-1001

随着气象部门装备保障业务重要性的不断提高,开展装备保障评估方法的研究,对保障质量进行科学评价成为一个新的课题。就监控、维护和维修3个装备保障子业务分别建立了各自的评估体系,还利用监控、维护和维修业务的独立性,提出了根据业务单位职责的组成,使用监控率、故障率和维修率三者的加权平均值评估装备保障综合效能的方法,对建立装备保障业务的考核体系有一定的参考借鉴意义。  相似文献   

基于激光雷达测风数据的复杂地形下风力机尾流特性研究          下载免费PDF全文

季明彬  高晓霞 《大气科学学报》2020,43(2):416-423

以张家口某处风电场为实验场地,采用两台多普勒激光雷达(Wind3D 6000和WindMast WP350)分别测量风力机的尾流和来流风速,对全尾流、半尾流和独立尾流3种工况进行研究。结果表明,3种工况下随着尾流发展尾流宽度均不断变大,而尾流深度和速度衰减则不断减小;全尾流和半尾流工况中,上游风力机的存在会增加下游风力机尾流宽度,且全尾流比半尾流的增加量大;全尾流和半尾流工况中,相较于上游风力机,下游风力机尾流深度和速度衰减均较小。  相似文献   

Geological Control of Fold Structure on Gas Occurrence and Its Implication for Coalbed Gas Outburst: Case Study in the Qinan Coal Mine,Huaibei Coalfield,China     

Zhang  Kaizhong  Wang  Liang  Cheng  Yuanping  Li  Wei  Kan  Jin  Tu  Qingyi  Jiang  Jingyu 《Natural Resources Research》2020,29(2):1375-1395

  相似文献   

汾河流域城乡聚落体系发展潜能测度及空间模式探究   总被引：1，自引：1，他引：0  

侯志华  刘敏  樊晓霞  贾宇平 《地理科学》2020,40(12):1978-1989

以11 188个自然聚落斑块为研究对象,基于场强模型,定量测度汾河流域城乡聚落体系发展潜能,借助GIS技术和地理探测器模型,分析其空间格局特征及驱动因素,进而探讨流域城乡融合发展空间模式。结果表明：① 城乡聚落斑块发展潜能差异显著,且空间分布极不均衡;纵向上中游流域高于下游流域高于上游流域,横向上河谷盆地区高于周边缓丘区高于两侧山丘区。② 聚落斑块发展潜能具有正向空间自相关性,高值斑块聚类显著;具有空间异质性特征且方向性明显,汾河主河道方向联动效应最强,空间联系最紧密;存在局域热点区,并呈现“主核–廊道–次核”的空间结构形态。③ 自然基础、社会经济发展水平和区位条件共同影响着城乡聚落体系发展潜质及空间结构形态;融合发展采取非均衡增长路径,市、县、镇、村全局考虑,构建“强化核心点–培育发展轴–扶持特色区–带动全流域”的逐层推进式空间发展模式。  相似文献   

基于卷积神经网络与条件随机场方法提取乡镇非正规固体废弃物     

刘懿兰  黄晓霞  李红旮  柳泽  陈崇  王新歌 《地球信息科学学报》2019,21(2):259-268

随着村镇经济建设发展,生活垃圾和工业固体废弃物造成的污染问题日益突出,已经成为制约新农村建设发展和生态文明建设的关键问题,而目前针对乡镇非正规固体废弃物的调查与统计主要依赖全国各乡镇相关部门逐级调查上报,工作量较大。本文基于高分辨率遥感影像,将深度学习模型和条件随机场模型相结合引入到乡镇固体废弃物的提取研究中,探索一种基于深度卷积神经网络的乡镇固体废弃物提取模型。由于固体废弃物在影像上表现为面积小,分布破碎等特点,为了提高工作效率,将模型特分为识别和提取2个部分：① 通过全连接卷积网络（CNN）对固体废弃物进行快速识别判断,筛选感兴趣区域影像块;② 在传统的全卷积神经网络(FCN)的基础上加入条件随机场模型(CRF)提取固体废弃物边界,提高整体分割精度。根据安徽、山西等地区相关部门上报固体废弃物堆放点以及住房与城乡建设部城乡规划管理中心进行野外检查的结果,实验最终识别精度达到86.87%以上;形状提取精度为89.84%,Kappa系数为0.7851,识别与提取精度均优于传统分类方法。同时,该方法已经逐步应用于住房和城乡建设部有关成都、兰州、河北等部分乡镇非正规固体废弃物的核查工作,取得了较为满意的结果。  相似文献   

花岗岩构造研究及花岗岩构造动力学刍议   总被引：15，自引：1，他引：14       下载免费PDF全文

王涛  王晓霞  郑亚东  洪大卫  王新社 《地质科学》2007,42(1):91-113

花岗岩可以视为一种很好的构造标志体,犹如褶皱、断裂一样。从花岗岩浆的形成、融体分离、岩浆上升到岩体定位以及变形改造的全过程都蕴含着丰富的构造动力学信息。研究花岗岩浆上升、迁移和定位可以探讨构造块体抬升及区域构造动力学。岩体生长方式与构造块体的运动学、动力学有密切的关系,极性生长揭示了上、下构造块体或岩石圈之间的相对的近水平方向剪切运移。变形花岗岩体是一种区域尺度的应变标志体,可以进行岩石有限应变测量和流变学参数估算,为分析区域构造变形特征提供应变参数。以对不同期次、不同变形程度花岗岩体为间接标志体,通过锆石定年可以限定变形的时间,特别是有可能确定早期变形的时间。岩体定位深度的系统研究有利于了解构造块体的抬升和深部构造作用。花岗岩构造与花岗岩成因类型特别是其演变研究的结合是判别构造块体动力学背景以及其转换的有效途径。通过这几方面的系统研究和有机结合,可以提供丰富的构造动力学信息,是否可能发展成较系统的花岗岩构造动力学值得探讨。  相似文献   

Facies character and geochemical signature in the late Quaternary meteoric diagenetic carbonate succession at the Xisha Islands,South China Sea     

Wanli Chen  Xiaoxia Huang  Shiguo Wu  Gang Liu  Haotian Wei  Jiaqing Wu 《海洋学报(英文版)》2021,40(3):94-111

The late Quaternary shallow-water carbonates have been altered by a variety of diagenetic processes, and further influenced by high-amplitude global and regional sea level changes. This study utilizes a new borehole drilled on the Yongxing Island, Xisha Islands to investigate meteoric diagenetic alteration in the late Quaternary shallowwater carbonates. Petrographic, mineralogical, stable isotopic and elemental data provide new insights into the meteoric diagenetic processes of the reef limestone. The results show the variation in the distribution of aragonite,high-Mg calcite(HMC) and low-Mg calcite(LMC) divides the shallow-water carbonates in Core SSZK1 into three intervals, which are Unit I(31.20–55.92 m, LMC), Unit II(18.39–31.20 m, aragonite and LMC) and Unit III(upper 18.39 m of core, aragonite, LMC and HMC). Various degrees of meteoric diagenesis exist in the identified three units. The lowermost Unit I has suffered almost complete freshwater diagenesis, whereas the overlying Units II and III have undergone incompletely meteoric diagenesis. The amount of time that limestone has been in the freshwater diagenetic environment has the largest impact on the degree of meteoric diagenesis. Approximately four intact facies/water depth cycles are recognized. The cumulative depletion of elements such as strontium(Sr),sodium(Na) and sulphur(S) caused by duplicated meteoric diagenesis in the older reef sequences are distinguished from the younger reef sequences. This study provides a new record of meteoric diagenesis, which is well reflected by whole-rock mineralogy and geochemistry.  相似文献   

Supplementation of Yeast Extract to Practical Diet Improves the Growth,Anti-Oxidative Capacity and Intestinal Morphology of Shrimp Litopenaeus vannamei     

MA Shuoli  WANG Xiaoxia  GAO Weihua  ZHANG Wenbing  MAI Kangsen 《中国海洋大学学报(英文版)》2019,(4)

Two control diets based on the commercial formula were designed to contain high(27%, D1) and low(22%, D2) levels of fish meal, respectively. Into D2, 500, 1000 and 1500 mg kg~(-1) of yeast extract were added, respectively, yielding three experimental diets(YE1 through YE3). Shrimp(initial body weight 0.30 g ± 0.02 g) were fed with the experimental diets, five tanks each diet and 30 shrimp individuals each tank, for 8 weeks, and then challenged with Vibrio parahaemolyticus. The results showed that the specific growth rate(SGR) of shrimp in D2 was significantly lower than that of shrimp in D1(P 0.05). The SGR of shrimp in YE3 was similar to that of shrimp in D1. The feed intake of shrimp was similar between D1 and D2. The feed conversion ratio and protein efficiency ratio of shrimp were similar among all diets(P 0.05). YE significantly improved the activity of glutathione S-transferase. The concentration of glutathione(GSH) and the total serum anti-oxidative capacity(T-AOC) of D1 were significantly higher than those of shrimp feeding other diets(P 0.05). The content of serum malondialdehyde of shrimp feeding YE2 and YE3 was significantly lower than that of shrimp feeding D2(P 0.05). The thickness of intestine muscular layer of shrimp feeding YE1 and YE2 was similar to that of shrimp feeding D1. The shrimp feeding YE1 showed the highest villus height of intestine among all groups. The cumulative mortality after challenging was similar among all groups(70.00%–86.67%)(P 0.05). In conclusion, 1000–1500 mg kg~(-1) of YE was suggested to be supplemented into the practical diets to improve the growth, anti-oxidative capacity and intestinal morphology of shrimp L. vannamei.  相似文献   

Effect of diet on the development,survival, and reproduction of the calanoid copepod Pseudodiaptomus dubia     

LUO Xiaoxia  LI Changling  HUANG Xianghu 《中国海洋湖沼学报》2019,(5)

Pseudodiapto,mus dubia is a calanoid copepod abundant in the mariculture ponds of southern China.However,our understanding of the population dynamics of P.dubia in aquaculture ponds is limited.In this study,groups of larval P.dubia were each fed a different microalgal species,and the effects of these different diets on development,survival,and reproduction were assessed.The five microalgae used were species common in aquaculture farms in China,and included two chlorophytes(Chlorella saccharophila and Platymonas subcordiformis),one golden microalga(Isochrysis zhan.jiangensis),and two diatoms(Chaetoceros muelleri and Cyclotella meneghinia,na).Our results indicated that C.saccharophila was not a suitable food for larval P.dubia,as all larvae fed this microalga died at stage Ⅲ(as copepodites).The survival rates of P.dubia larvae fed C.muelleri,Ⅰ. zhanjiangensis,and P.subcordiformis were significantly higher than that of larvae fed C.meneghiniana.In the adult stage,copepods fed C.muelleri,I. zhanjiangensis,and C.meneghiniana produced more nauplii(430-566 nauplii/female),had higher intrinsic growth rates(0.2-0.253/d),and better longevity(59-60 days)than those fed P.subcordiformis.Our results therefore suggest that P.dubia has different nutritional needs and food preferences at different life stages.For example,P.subcordifonnis was suitable for developing larvae but not for breeding adults,while C.meneghiniana was suitable for breeding adults but not for developing larvae.Both C.muelleri and I.zhanjiangensis were excellent foods for P.dubia throughout the entire life cycle.  相似文献