雷暴对流起电机制理论分析          下载免费PDF全文

言穆弘  郭昌明  刘欣生 《大气科学》1991,15(2):120-128

本文用一维分层模式理论分析了地面降雨、尖端放电、对流运动以及云外电导率变化对雷暴电结构的影响。分析指出,云内对流强度明显地影响着雷暴电结构,强烈的地面降雨和尖端放电可使地面电场强度显著减小,甚至极性翻转。闪电和云顶附近的下沉气流是维持雷暴向上提供充电电流的重要条件。在雷暴中,对流起电机制是一个不可忽略的重要过程。  相似文献   

利用遥感技术监测船舶航速的方法研究     

王红梅  潘广东  王超  郭子祺 《遥感学报》2001,5(2):149-153

主要讨论了两种利用遥感技术提取水面运动船舶的航速方法：利用波高谱信息提取航速和利用船尾迹中的横波信息提取航速。作者介绍了这两种方法的原理，描述了利用遥感技术提取船舶航速的工作流程，并利用模拟和实测的船尾迹波高数据对这两种方法进行了验证。从计算结果看，两种方法精度都能满足仅要求航速量级的需求者，利用波高谱信息的方法误差（10％左右）小于利用横波信息的方法误差（20％左右）。该项研究为实时或近实时探测运动船舶航速提供了新的方法。  相似文献   

三维激光扫描技术在船体外形测量中的试验性研究   总被引：5，自引：1，他引：5  

李欣  周佳玮  刘正国  胡震天 《测绘信息与工程》2006,31(6):36-37

介绍了三维激光扫描技术的测量原理,进行了21 m长船体外形测量的试验性研究,证明了其在快速、高效获取船体三维数据、提取船体型线方面有着较大的优越性。  相似文献   

The Wave Energy Concentration at the Agulhas Current off South Africa   总被引：3，自引：0，他引：3  

Lavrenov  I. V. 《Natural Hazards》1998,17(2):117-127

The case of a freak wave collision with the ship in the Agulhas current is described. The explanation of the appearance of the freak wave as a result of wind-wave transformation in the Agulhas current is given. Swell is captured and intensified by the counter-current and is located in the neighbourhood of the maximum value of the current velocity, as a result of which there is a great concentration of wave-energy density. The superposition of wind and sea with swell transformed by the current promotes the formation of the freak waves. Using a simple mathematical analysis, an optimal ship track is proposed which could reduce the risk of collision with a freak wave.  相似文献   

Econometric analysis of the ship demolition market     

Sabine Knapp  Shashi N. Kumar  Anna Bobo Remijn   《Marine Policy》2008,32(6):1023-1036

The topic of ship recycling has obtained considerable attention during the last two decades for a variety of reasons with the likelihood of the adoption of a new international convention under the auspices of the International Maritime Organization (IMO). This study applies econometric modeling to a unique data set to provide insight into the dynamics of the ship recycling market. The data set contains information on 51,112 ships over 100 gt and includes 748,621 events over a period of 29 years. The analysis confirms a negative relationship of earnings and a positive relationship of scrap prices for all locations while Bangladesh seems to be more sensitive to changes in earnings than the other locations and more likely demolishes larger and older vessels. The results for flag and ownership vary across scrapping locations with Malta and Cyprus indicating potential importance from a registry perspective. The overall safety profile of a vessel seems to be less important towards the probability of a ship being scrapped. Possible implementation of the convention at EU level will mostly likely affect Turkey while non-ratification of one of the major flags will most likely affect China or Bangladesh.  相似文献   

基于BDS的混合动力船舶节能研究   总被引：1，自引：0，他引：1       下载免费PDF全文

王永鼎  程湘裕 《全球定位系统》2020,45(2):112-118

提出一种基于北斗卫星导航系统(BDS)的油电混合动力推进系统,柴油机和电动机采取PTH驱动方式,采用燃油和电能混合提供推进动力,可以依据BDS导航的航行区域以及航行速度选择不同动力源输出.经过燃油经济性和效益分析,与传统推进系统相比,应用基于BDS的混合动力推进系统,公务船运营成本降低26%,增加的初始建造投资成本3年内可以收回;金枪鱼延绳钓船综合节油15%~20%,通过节油方式可在4年内收回初始建造投资成本.基于BDS的混合动力系统可以增加推进冗余度,提高船舶安全性,具有良好的节能减排和节约运营成本的效果.  相似文献   

船行波对H-ADCP 影响分析研究     

《海洋技术学报》2024,(1)

作为当今世界上最先进的测流仪器，水平式声学多普勒流速剖面仪（Horizontal Acoustic Doppler Current Profiler，H-ADCP） 因其精度高、速度快等突出优势在河流中的应用越来越广泛，但在航运业发达地区，由于受船行波的影响，很难得到稳定可靠的流速数据，阻碍了H-ADCP在平原河网地区的应用和推广。目前技术上很难做到完全消除船行波的影响，本文将H-ADCP应用在平原河网地区对流速进行测量，并分析了船行波对测量精度的影响。从H-ADCP设备选型、测量和安装方式、测量预处理、数据后处理等多方面入手，可以有效消减船行波对H-ADCP 的影响，从而提高测流精度。同时，通过实验测量断面一天内平均流速变化情况，得到受船行波影响后的流速波形，然后采用数据处理手段，验证了所提方法的可行性。  相似文献   

基于Google Maps API的船舶自动站监控Web设计     

刘艳中  李建勇  陈冰怀 《气象科技》2015,43(4):643-646

简要介绍了Google Maps JavaScript API技术,并着重阐述了其作为主流的WebGIS技术在船舶自动气象站监控页面设计中的应用,包括：通过JavaScript和AJAX技术请求远程数据服务器获取气象数据、状态数据及GIS信息等,并将返回的JOSN格式数据加载到Google Map上,同时通过Google Maps JavaScript定制化船舶图标并对加载的船舶轨迹进行渲染,使用户需要的监控信息更加直观地显示在监控页面上。本文结果已成功应用到广东省气象局设备全网监控系统之中。  相似文献   

船舶自动气象站分类标准及仪器布设原则     

张玉洁  安忠亮  高林  涂爱琴  宋传经 《山东气象》2015,35(3):40-43

本文在研究分析各类船舶的基础上,对船舶自动气象站(船舶站)的基本构成和采集要素进行了分类,提出了船舶站构成的分类标准,解决了不同船舶选取安装不同要素自动站选择依据不足的问题,详述了船舶站的构成。以典型船舶站为例,详述了温、压、湿、风、降水、能见度、辐射等观测要素的安装位置选择,为船舶站的设计和安装提供参考依据。  相似文献   

Chemical contamination of a coral reef by the grounding of a cruise ship in Bermuda   总被引：1，自引：0，他引：1  

Jones RJ 《Marine pollution bulletin》2007,54(7):905-911

Bulk metal analyses of surficial sediments collected around the Norwegian Crown cruise ship grounding site in Bermuda indicated significant but localized contamination of reef sediments by copper and zinc, caused by the stripping of the tri-butyltin (TBT)-free antifouling (AF) paint (Intersmooth 460) from the underside of the hull. Highest copper and zinc values were found in heavily compacted and red-pigmented sediments inside the impact scar and were comparable to levels found close to slip ways of local boat yards where AF paints from hull stripping and cleaning processes are washed into the sea. The re-distribution of AF contaminated sediments by storms and deposition on nearby reefs constitutes a significant ecological risk that could delay recovery processes and reduce the effectiveness of remediation efforts. Whilst the ecotoxicological effects of AF paint particles interspersed with sediment is unknown, and in need of further study, it is argued that the significance of AF paint contamination of grounding sites has been overlooked.  相似文献