调水调沙期间黄河口羽状流的逐时变化     

于永贵  石学法  迟万清  胡子峰  乔淑卿 《海洋地质与第四纪地质》2018,(5)

2002年黄河实施调水调沙以来,黄河入海泥沙普遍以异轻羽状流的形式在河口附近的有限区域内堆积下来。采用2011年、2012年以及2013年调水调沙期间3期静止轨道海洋水色卫星(GOCI)数据对黄河口附近海域进行悬浮物浓度反演,提取了黄河口羽状流的逐时变化信息;通过黄河口水动力数值模拟以及风场、潮汐等实测数据分析,阐明了羽状流逐时变化的驱动机制。研究结果表明:黄河调水调沙前后黄河口羽状流表现出单向变化和往复变化两种不同的变化过程;而悬浮物浓度的逐时变化显示:河口附近不同站位的悬浮物浓度逐时变化过程差异较大,同一站位的悬浮物浓度可在1小时之内升高或降低约100mg/L。单向变化型羽状流主要受单向潮流的控制,且GOCI观测时段位于一个落潮或者涨潮过程,河流动力较弱;往复变化型羽状流受涨、落潮往复潮流的控制,涨、落潮流向的转换驱使羽状流向相反的方向运动,而且羽状流位于潮流切变带以内,切变锋对羽状流的形态、分布范围具有明显的切变效应。  相似文献   

基于楼层剪力的等效阻尼比计算方法研究     

韩宇娴  商城豪  陈清祥  周云 《地震工程与工程振动》2021,41(1):161-167

针对现有附加有效阻尼比计算方法存在的问题,本文从能量的角度揭示了阻尼比对结构影响的机理。从结构设计的角度,提出一种在时程分析下基于楼层剪力的消能减震结构等效阻尼比计算方法。对布置黏滞阻尼器和软钢阻尼器的消能减震模型,采用本文提出的等效阻尼比计算方法,建立等效结构进行结构响应对比。结果表明,由该计算方法得到的等效阻尼比能够准确地评估阻尼器在结构中的耗能效果,建立的等效结构能够准确反映消能减震结构实际情况。基于楼层剪力的等效阻尼比计算方法通过等效结构楼层剪力大于或等于消能减震结构楼层剪力判断迭代完成,该方法计算过程不涉及阻尼器参数及结构形式,适用于所有阻尼器类型与结构类型。计算得到的等效结构进行设计能够确保结构设计的安全。  相似文献   

中医综合护理干预癫痫42例效果观察          下载免费PDF全文

侯盈文  林少怡  胡子衡 《应用海洋学学报》2022,38(5):84

目的：观察中医综合护理对癫痫患者的干预效果。方法：选取84 例癫痫患者为研究对象,采用随机数字表法将其分为观察组与对照组,每组各42 例。对照组实施常规护理干预,观察组在对照组的基础上实施中医综合护理,观察2组干预前后1个月癫痫发作次数及持续时间,焦虑自评量表（SAS）、抑郁自评量表（SDS）、洛文斯顿作业疗法认知评定量表（LOTCA)积分,以及护理满意度。结果：干预后观察组癫痫发作次数少于对照组,癫痫持续时间短于对照组,SAS、SDS积分均显著低于对照组,LOTCA各项积分显著高于对照组,差异均有统计学意义（P<0.01）,护理总满意率观察组为92.86%（39/42）,差异有统计学意义,显著高于对照组的73.81%（31/42）（P<0.05）。结论：针对癫痫患者实施中医综合护理可显著减少其癫痫发作次数,缩短癫痫持续时间,改善患者不良情志及认知功能,并能提高患者护理满意度,值得临床推广应用。  相似文献   

城市社区养老设施配置空间均衡研究     

李海萍  梁子豪 《地球信息科学学报》2021,23(3):467-478

我国人口老龄化增速势头不减,存在养老服务业发展不平衡、老龄服务供给不足的矛盾。北京是较早进入老龄化的城市,提出了以居家为主的“9064”养老模式以解决养老资源缺口问题。为促进社区养老服务供给的便利化,提高老年群体对养老服务的“获得感”,本文以北京市海淀区老年人口密度较大的17个街道为研究区,采用百度POI、小区户数、高德地图和遥感影像等多源数据,对老年人口统计数据进行空间网格化,比较国家、省（市）社区养老设施的服务半径及调查所得老年人日常出行特征,引入北京市居住公共服务设施配置指标作为评价标准,应用改进型两步移动搜索算法并构建空间均衡系数,从服务覆盖率、供需比和医疗资源易获性3个方面对社区养老设施进行空间均衡研究。结果表明,研究区内社区养老驿站的数量仍有不足,不同半径下的服务覆盖率和供需比差异显著,500 m半径内的覆盖率仅为23.3%,空间分布不合理是超八成社区养老驿站供需比偏低的主要原因,基层社区卫生机构对医疗资源的易获性有积极作用;社区养老服务发展不均衡,需要进一步优化配置。  相似文献   

庐山层状云和对流云雨滴谱比较分析   总被引：1，自引：0，他引：1  

张欢  濮江平  胡子浩  张小鹏  王一琛 《气象科学》2014,34(5):483-490

本文从庐山近3 a的雨滴谱观测资料中选取数例层状云降水和对流云降水个例,通过对两类云降水的平均雨滴谱分析拟合、各微物理量演变以及速度谱的对比研究,得出以下结论:庐山对流云降水的平均雨滴谱很宽,有直径大于10 mm的大雨滴出现。Γ分布,对层状云降水拟合,较MP分布差,而对对流云降水拟合,较MP分布好。两类云降水的雨强变化都是由最大雨滴直径和粒子数浓度共同决定的,但对于对流云降水,最大雨滴直径的决定作用更为重要。雨滴直径较小时,两类云降水的实测速度大于经验公式值;而雨滴直径较大时,实测速度值分布在经验公式曲线两侧,但对流云降水的分布偏差要大于层状云降水。  相似文献   

美国大规模调水的经济效益问题     

C.W.豪  云浦 《地理科学进展》1984,3(4):19-23

Ⅰ.现有的与予计的调水情况美国的降水分布是很不均匀的。粗略地说,这个国家的东部水资源丰沛而西部则干旱少雨。所以,毫不足怪,东部的水质问题比较突出,而高部水量问题则占首要地位。因而,西部地区对跨流域调水抱有极大的兴趣。  相似文献   

湖南近五年来之雾     

欧阳楚豪 《气象学报》1943,(Z1)

一、日之天气 雾之形成,须有待於静隐层结乏气团。於时风力微弱,对流不盛。故凡以足以扰动气团层结之因子,如风力增大气温升高等,均类能防础雾之发生,尤以辐射类为然。兹将湘省之长沙、常德、衡阳三地雾日之天气状况分述於下:  相似文献   

近年来人类活动影响下长江河口的变化模式     

王成龙  赵一飞  邹欣庆  许鑫王豪  葛晨东 《海洋学报(英文版)》2017,36(4):87-96

To evaluate the controlling factors for coastline change of the Changjiang(Yangtze River) Estuary since 1974,we extracted the mean high tide line from multi-temporal remote sensing images that span from 1974 to 2014 at 2-year intervals.We chose 42 scenes to constrain the changing pattern of the Changjiang Estuary coastline,and implemented GIS technology to analyze the area change of the Changjiang(Yangtze) Subaerial Delta.Runoff,sediment discharge and coastal engineering were withal considered in the analysis of the coastline changes.The coastline has transgressed seaward since 1974,and a part of it presents inter-annual variations.The area of the Changjiang Subaerial Delta increased by 871 km2,with a net accretion rate of 21.8 km2/a.Based on the change of sediment discharge due to the major projects in the Changjiang River Basin,we divided the changing pattern of the coastline into three stages:the slow accretion stage(1974–1986),the moderate accretion stage(1987–2002),and the rapid accretion stage(2003–2014).Liner regression analysis illustrated that there is a significantly positive correlation between the area changes and sediment discharge in the Chongming Eastern Shoal and Jiuduansha.This suggested that sediment load has a fundamental effect on the evolution of the Changjiang Estuary.Construction of Deep Waterway in the North Passage of the Changjiang River(1998–2010) led to a rapid accretion in the Hengsha Eastern Shoal and Jiuduansha by influencing the hydrodynamics in North Passage.Coastal engineering such as reclamation and harbor construction can also change the morphology of the Changjiang Estuary.We defined a contribution rate of area change to assess the impact of reclamation on the evolution of Changjiang Estuary.It turned out that more than 45.3% of area increment of the Changjiang Estuary was attributed to reclamation.  相似文献   

苏北滨海湿地互花米草潮滩CO₂,CH₄和N₂O通量的日变化规律     

许鑫王豪  傅光翮  邹欣庆  葛晨东  赵一飞 《海洋学报(英文版)》2017,36(4):105-113

The invasions of the alien species such as Spartina alterniflora along the northern Jiangsu coastlines have posed a threat to biodiversity and the ecosystem function.Yet,limited attention has been given to their potential influence on greenhouse gas(GHG) emissions,including the diurnal variations of GHG fluxes that are fundamental in estimating the carbon and nitrogen budget.In this study,we examined the diurnal variation in fluxes of carbon dioxide(CO_2),methane(CH_4),and nitrous oxide(N2O) from a S.alterniflora intertidal flat in June,October,and December of 2013 and April of 2014 representing the summer,autumn,winter,and spring seasons,respectively.We found that the average CH_4 fluxes on the diurnal scale were positive during the growing season while negative otherwise.The tidal flat of S.alterniflora acted as a source of CH_4 in summer(June) and a combination of source and sink in other seasons.We observed higher diurnal variations in the CO_2 and N_2O fluxes during the growing season(1 536.5 mg CO_2 m~(–2) h~(–1) and 25.6 μg N_2O m~(–2) h~(–1)) compared with those measured in the non-growing season(379.1 mg CO_2 m~(–2) h~(–1) and 16.5 μg N_2O m~(–2) h~(–1)).The mean fluxes of CH_4 were higher at night than that in the daytime during all the seasons but October.The diurnal variation in the fluxes of CO_2 in June and N_2O in December fluctuated more than that in October and April.However,two peak curves in October and April were observed for the diurnal changes in CO_2 and N_2O fluxes(prominent peaks were found in the morning of October and in the afternoon of April,respectively).The highest diurnal variation in the N_2O fluxes took place at 15:00(86.4 μg N_2O m~(–2) h~(–1)) in June with an unimodal distribution.Water logging in October increased the emission of CO_2(especially at nighttime),yet decreased N_2O and CH_4 emissions to a different degree on the daily scale because of the restrained diffusion rates of the gases.The seasonal and diurnal variations of CH_4 and CO_2 fluxes did not correlate to the air and soil temperatures,whereas the seasonal and diurnal variation of the fluxes of N_2O in June exhibited a significant correlation with air temperature.When N_2O and CH_4 fluxes were converted to CO_2-e equivalents,the emissions of N_2O had a remarkable potential to impact the global warming.The mean daily flux(MF) and total daily flux(TDF) were higher in the growing season,nevertheless,the MF and TDF of CO_2 were higher in October and those of CH_4 and N_2O were higher in June.In spite of the difference in the optimal sampling times throughout the observation period,our results obtained have implications for sampling and scaling strategies in estimating the GHG fluxes in coastal saline wetlands.  相似文献   

西部荒漠地区的湿地和水禽多样性   总被引：7，自引：1，他引：7  

刘迺发  黄族豪  文陇英 《湿地科学》2004,2(4):259-266

我国西部荒漠地区约有自然和人工湿地 96 180km2 ,这些湿地按成因分为断层陷落积水成湿地 ,冰川湖湿地 ,地下水浅出湿地 ,灌溉退水湿地和人工湿地。栖息着《湿地公约》规定的水禽 14 2种 ,占我国水禽种数的5 4 .8% ,其中繁殖种类 74种 ,占 5 2 .1%。列入国家野生动物重点保护名录的 2 6种 ,占 18.3% ,占我国列入保护名录水禽种数的 5 0 .0 %。列入《濒危野生动植物物种国际贸易公约》(CITES)的 12种 ,占 8.4 % ;列入《中日候鸟及其栖息环境保护协定》的 84种 ,占 5 9.2 %。荒漠地区湿地对水禽迁徙、繁殖、越冬有着特殊重要的作用。自然环境改变 ,尤其气候变干旱和人类活动严重影响着荒漠地区湿地的存在 ,对水禽的物种多样性和种群数量产生了强烈影响。应加强荒漠地区湿地保护  相似文献