A fast inversion method for ocean parameters based on dispersion curves with a single hydrophone

The dispersion characteristics of shallow water can be described by the dispersion curves, which contain substantial ocean parameter information. A fast ocean parameter inversion method based on dispersion curves with a single hydrophone is presented in this paper. The method is achieved through Bayesian theory. Several sets of dispersion curves extracted from measured data are used as the input function. The inversion is performed by matching a replica calculated with a dispersion formula. The bottom characteristics can be described by the bottom reflection phase shift parameter P. The propagation range and the depth can be inverted quickly when the seabed parameters are represented by on parameter P. The inversion results improve the inversion efficiency of the seabed parameters. Consequently, the inversion efficiency and accuracy are improved while the number of inversion parameters is decreased and the computational speed of replica is increased. The inversion results have lower error than the reference values, and the dispersion curves calculated with inversion parameters are also in good agreement with extracted curves from measured data; thus, the effectiveness of the inversion method is demonstrated.     

Numerical Simulation of Icing on Nrel 5-MW Reference Offshore Wind Turbine Blades Under Different Icing Conditions

Offshore wind energy resources are operational in cold regions, while offshore wind turbines will face the threat of icing. Therefore, it is necessary to study icing of offshore wind turbines under different icing conditions. In this study, icing sensitivity of offshore wind turbine blades are performed using a combination of FLUENT and FENSAP-ICE software, and the effects of liquid water content (LWC), medium volume diameter (MVD), wind speed and air temperature on blade icing shape are analyzed by two types of ice, namely rime ice and glaze ice. The results show that the increase of LWC and MVD will increase the amount of ice that forms on the blade surface for either glaze ice or rime ice, and an increase of MVD will expand the adhesion surface between ice and blade. Before reaching the rated wind speed of 11.4 m/s, it does not directly affect the icing shape. However, after reaching the rated wind speed, the attack angle of the incoming flow decreases obviously, and the amount of ice increases markedly. When the ambient air temperature meets the icing conditions of glaze ice (i.e., −5°C to 0°C), the lower the temperature, the more glaze ice freezes, whereas air temperature has no impact on the icing of rime ice. Compared with onshore wind turbines, offshore wind turbines might face extreme meteorological conditions, and the wind speed has no impact on the amount of ice that forms on the blade surface for most wind speeds

     

FY-3D卫星MWHS-2辐射率资料直接同化对台风“米娜”预报的影响*

文章基于天气研究和预报(weather research and forecasting, WRF)模式中的FY-3D卫星微波湿度计Ⅱ(micro-wave humidity sounder 2, MWHS-2)辐射率资料的直接同化模块, 采用三维变分(three dimensional variation, 3DVar)方法在晴空条件下同化MWHS-2辐射率资料, 考察MWHS-2辐射率资料同化对台风“米娜”(2019)预报的影响。文中设计了4组试验, 第一组试验不同化任何资料, 第二组试验同化了单独的全球通信系统(global telecommunications system, GTS)常规资料, 第三组试验联合同化了GTS常规资料和MWHS-2辐射率资料, 第四组试验将MWHS-2辐射率资料换成先进技术微波探测计(advanced technology microwave sounder, ATMS)辐射率资料同化。研究结果表明: 偏差订正后各通道观测和背景场差值的均值趋于0, 同化后分析场相对观测的标准差与均方根误差较背景场显著减小, 同化过程是有效的。与仅同化GTS常规资料和同化ATMS资料的试验相比, 同化晴空MWHS-2辐射率资料后的增量场在台风中心附近有负的高度增量和正的温度增量, 从动力与热力上有助于台风的维持。在确定性预报最后的12h, 同化晴空MWHS-2辐射率资料的试验能够改进500hPa环流形势的模拟, 加强西南方向引导气流的强度, 从而最终减小台风路径预报的误差。     

Relationships between fractal road and drainage networks in Wuling mountainous area: Another symmetric understanding of human-environment relations

Symmetrical relationships between humans and their environment have been referred to as an extension of symmetries in the human geographical system and have drawn great attention. This paper explored the symmetry between physical and human systems through fractal analysis of the road and drainage networks in Wuling mountainous area. We found that both the road and drainage networks reflect weak clustering distributions. The evolution of the road network shared a significant self-organizing composition, while the drainage network showed obvious double fraetal characteristics. The geometric fractal dimension of the road network was larger than that of the drainage network. In addition, when assigned a weight relating to hierarchy or length, neither the road network nor drainage network showed a fractal property. These findings indicated that the fractal evolution of the road network shared certain similarities with fractal distribution of the drainage network. The symmetry between the two systems resulted from an interactive process of destroying symmetry at the lower order and reconstructing symmetry at the higher order. The relationships between the fractal dimensions of the rural-urban road network, the drainage network andthe urban system indicated that the development of this area was to achieve the symmetrical isomorphism of physical-human geographical systems.     

孑遗植物四合木(Tetraena mongolica)异地保护条件下的气候生物学特征与光合效率

为了廓清异地保护条件下孑遗濒危植物四合木(Tetraena mongolica)的气候生物学特征、光合生理生态适应性及生境适宜性,应用1971—2011年的地面气象资料进行了不同试验区的气候生物图解与分析,测定了四合木及其伴生种白刺(Nitraria tangutorum)的叶片气体交换参数及光合效率。结果表明:①四合木自然分布区(内蒙古乌海地区)与异地保护区的气候生物学特征存在明显分异;②当年种植的四合木实生苗的生长量大小依次为:乌海四合木核心区实生苗鄂尔多斯实生苗阿拉善实生苗;③自然条件下,5个处理的净光合速率(Pn)依次为阿拉善移植的四合木成株(24.05±1.68μmol·m-2·s-1)乌海客土栽培的四合木(19.97±1.05μmol·m-2·s-1)乌海栽培的四合木实生苗(18.96±1.04μmol·m-2·s-1)鄂尔多斯栽培的四合木实生苗(16.64±0.92μmol·m-2·s-1)阿拉善栽培的四合木实生苗(16.48±0.13μmol·m-2·s-1);异地保护试验区栽培的四合木实生苗的Pn没有明显差异(p≥0.05),即原生境条件下栽培的四合木实生苗的Pn较高。同时,异地保护栽培四合木实生苗中,鄂尔多斯栽培的四合木实生苗的Pn阿拉善栽培的四合木实生苗。从四合木光合作用特征中的Pn、蒸腾速率、气孔导度和胞间CO2浓度、气候生物学特征和生长量等综合研究结果可以推断,从原生境区东移的实生苗迁地保护,使四合木具有更高的生理生态适宜性和环境适应性。     

深圳产业演进规律及空间分布格局

根据1979—2012年深圳企业数据,以ADF方法进行单位根检验,发现企业时序变量为1阶单整序列,继而进行协整检验和Granger检验,结合VAR和VEC模型计量结果,探讨了深圳第二产业和第三产业企业在演进过程中的长期均衡关系、短期因果关系和动态冲击影响,并基于企业区位熵法对产业演进结果的空间表现形态进行了分析,发现深圳产业发展过程中存在协整关系,第三产业企业增长是第二产业企业出现的Granger原因,脉冲响应函数反映两者相互的动态影响,产业协同演进结果空间分布上存在着分异现象。在研究结果的基础上提出相应的政策建议,以期促进城市产业合理演进。     

中国西北地区城市网络体系分析——基于民营企业布局

从民营企业视角对中国西北地区的城市网络体系进行实证分析,透视民营企业对其城市网络形成的作用。利用民营企业的分布数据,借鉴城市网络分析方法,从服务值、连通性、网络性3个方面对西北地区的城市网络体系进行了分析。基于民营企业视角,西北地区的城市构成了以西安和乌鲁木齐为主副双核、省会城市为核心节点、其他城市可作为其辐射区域的网络系统,且基于民营企业的城市网络体系尚处于初级发展阶段。     

土壤氮、盐浓度对盐角草(Salicornia europaea)生长发育及氮素吸收的影响

以盐生植物盐角草(Salicornia europaea)为材料,以NaCl模拟不同盐度环境,盆栽试验了氮(0.3g·kg-1,N1;0.6g·kg-1,N2;1.2g·kg-1,N3;2.4g·kg-1,N4)、盐(2.5g·kg-1,S1;5.0g·kg-1,S2;7.5g·kg-1,S3)处理对其生长发育及氮素吸收利用的影响。结果表明:(1)不同盐度下施氮均可以显著促进盐角草的生长,地上部干质量均在N2处理下达到最大,而株高均在N1时达到最高,且施氮对盐角草生长的影响与盐度有关;(2)不同盐度环境下施氮所能达到的最高干物质产量及最高施氮限量不同,表现为S3S1S2,随着施氮量的增加,氮素生产力与氮素农学利用效率均表现出下降的趋势;(3)施氮显著增加了盐角草各器官含氮量及氮吸收量,同一施氮水平下盐角草各器官含氮量及氮吸收量均表现为同化枝茎根;(4)同一施氮水平下,随着盐度的增加,盐角草同化枝渗透势显著下降,同一盐度环境下,随着施氮量的增加,同化枝渗透势呈现出下降趋势,渗透调节能力增大;(5)3个盐度环境下,施氮均增加盐角草同化枝光合色素含量,从而提高光合效率,增强其对盐渍环境的适应能力。     

基于GPS反射信号的岸基海冰探测的研究

本文论述了全球导航卫星系统反射信号测量（GNSS-R）在海冰介电常数和海冰密集程度方面的潜在的研究价值,对欧洲空间局在格林兰岛迪斯科海岸采集的海冰数据进行分析,处理了两种反射信号的幅度的量化关系,同时跟踪多颗GNSS卫星并且保证了数据处理时间的连续性和有效性。根据双极化反射信号的幅度极化比和模拟海冰表面复介电常数得出结论, 幅度极化比和海冰表面的介电常数变化有联系。     

休闲旅游——国内外研究现状、差异与内涵解析

休闲旅游是当前我国旅游业发展的热点,政府和业界都对休闲旅游的发展高度重视,国内学术界也对这一问题进行了大量研究,但迄今为止有关休闲旅游的内涵仍缺乏统一的认识,这不利于人们对休闲旅游做进一步的深入研究。该文基于对国内外研究现状的分析,阐释了休闲旅游与休闲、旅游、观光旅游和度假旅游等概念之间的关系,并结合我国旅游发展的情境和特点,尝试性地对休闲旅游的内涵进行了解析,以期能够为休闲旅游未来的研究和实践发展提供一定的理论指导。