中国乡村旅游发展综述

乡村旅游是以农业为基础,以旅游为目的,以服务为手段,以城市居民为目标,第一产业和第三产业相结合的新型产业.乡村旅游可以合理开发城市边缘区景观生态资源,发展城郊生态旅游,实现城市和乡村优势互补、协调发展.乡村旅游在中国先后经历了早期兴起阶段、初期发展阶段和规范经营阶段,从最初的资源特色主导、农业产业主导和政府扶持主导过渡到了现今的市场主导.本文基于乡村旅游的产生背景和概念特征,对中国乡村旅游的发展进行了全面论述,分析了乡村旅游的发展现状和主要模式,并针对当前存在的主要问题提出了相应的发展对策,最后对乡村旅游的发展前景进行了展望,以期能用以指导未来中国乡村旅游的可持续发展.     

Response of upper ocean currents to typhoons at two ADCP moorings west of the Luzon Strait

We deployed two ADCP mooring systems west of the Luzon Strait in August 2008, and measured the upper ocean currents at high frequency. Two typhoons passed over the moorings during approximately one-month observation period. Using ADCP observations, satellite wind and heat flux measurements, and high-resolution model assimilation products, we studied the response of the upper ocean to typhoons. The first typhoon, Nuri, passed over one of the moorings, resulting in strong Ekman divergence and significant surface cooling. The cooling of surface water lagged the typhoon wind forcing about one day and lasted about five days. The second typhoon, Sinlaku, moved northward east of the Luzon Strait, and did not directly impact currents near the observation regions. Sinlaku increased anomalous surface water transport exchange across the Luzon Strait, which modulated the surface layer current of the Kuroshio.     

含二阶规则起伏体结构面的剪切试验研究

通过常法向应力直剪试验研究了含不同二阶规则起伏体高度结构面的剪切特性。试验结果表明:与只含一阶起伏体结构面不同,含二阶起伏体结构面会有多峰值剪应力和波浪状的变形曲线,会出现多次剪断破坏或一次剪断破坏的破坏特征,随着二阶起伏体高度的增大,结构面剪切强度增大。     

路基沉降预测的三点修正指数曲线法

科学、合理地预测路基工后沉降量是高速铁路建设的关键环节。针对武广高速铁路路基沉降量级小、数据相对波动大的实测数据,探讨了指数曲线法对无砟轨道路基沉降预测的适用性,发现指数曲线法不能直接应用于量级小、数据相对波动较大的沉降预测。把三点法的基本思想引入指数曲线模型,对指数曲线法进行了改进,提出了路基沉降预测的三点修正指数曲线模型。结合武广高速铁路路基沉降观测数据,分析了三点修正指数曲线模型的特性。分析表明,在整个沉降曲线上选取3个关键点作为预测样本,很好地回避了数据波动带来的影响;沉降曲线上“拐点”以后的沉降规律更符合指数曲线模型,因此,应取沉降曲线上“拐点”以后的数据作为样本值,所取三点应能尽量反映沉降发展的趋势。三点修正指数曲线法预测结果稳定、相关系数高,具有一定的工程应用价值     

铁还原地下水环境中微生物降解苯和甲苯的碳源 专一性分析

文中研究在粒状铁化学还原三氯乙烯渗透反应格栅和生物降解苯和甲苯渗透反应格栅的联合格栅技术中,下游生物降解格栅中铁还原环境下微生物对苯和甲苯的生物降解。通过模拟粒状铁渗透反应格栅下游铁还原环境,主要研究微生物以苯、甲苯作为碳源时,对碳源的专一性。通过批实验发现,对于分别用苯和甲苯培养驯化的微生物,互换碳源后,微生物对2 000.00μg/L苯和甲苯的生物降解半衰期分别由之前的1.0和1.5 d减少到0.7和1.0 d,互换碳源后苯和甲苯的去除率分别增加38%和32%。在粒状铁渗透反应格栅下游生物降解渗透反应格栅中,微生物在铁还原环境下以苯、甲苯作为碳源时对碳源没有专一性,苯和甲苯可以同时被生物降解去除。     

地磁测量卫星

地磁测量卫星是地磁测量的重要工具,它相对于一般地磁测量仪器具有覆盖面广、精度高、实时采集和处理等特点.本文按照发射时间,介绍了早期的POGO、Magsat等磁测卫星,并重点介绍了现仍在使用的Oersted卫星和CHAMP卫星,以及2012年将要发射的Swarm卫星.同时阐述了这些卫星的结构、工作原理和主要的磁测仪器,最后介绍了卫星资料在各领域的应用.     

Coupled assimilation for an intermediated coupled ENSO prediction model

The value of coupled assimilation is discussed using an intermediate coupled model in which the wind stress is the only atmospheric state which is slavery to model sea surface temperature (SST). In the coupled assimilation analysis, based on the coupled wind–ocean state covariance calculated from the coupled state ensemble, the ocean state is adjusted by assimilating wind data using the ensemble Kalman filter. As revealed by a series of assimilation experiments using simulated observations, the coupled assimilation of wind observations yields better results than the assimilation of SST observations. Specifically, the coupled assimilation of wind observations can help to improve the accuracy of the surface and subsurface currents because the correlation between the wind and ocean currents is stronger than that between SST and ocean currents in the equatorial Pacific. Thus, the coupled assimilation of wind data can decrease the initial condition errors in the surface/subsurface currents that can significantly contribute to SST forecast errors. The value of the coupled assimilation of wind observations is further demonstrated by comparing the prediction skills of three 12-year (1997–2008) hindcast experiments initialized by the ocean-only assimilation scheme that assimilates SST observations, the coupled assimilation scheme that assimilates wind observations, and a nudging scheme that nudges the observed wind stress data, respectively. The prediction skills of two assimilation schemes are significantly better than those of the nudging scheme. The prediction skills of assimilating wind observations are better than assimilating SST observations. Assimilating wind observations for the 2007/2008 La Niña event triggers better predictions, while assimilating SST observations fails to provide an early warning for that event.     

A three-dimensional surface wave–ocean circulation coupled model and its initial testing

A theoretical framework to include the influences of nonbreaking surface waves in ocean general circulation models is established based on Reynolds stresses and fluxes terms derived from surface wave-induced fluctuation. An expression for the wave-induced viscosity and diffusivity as a function of the wave number spectrum is derived for infinite and finite water depths; this derivation allows the coupling of ocean circulation models with a wave number spectrum numerical model. In the case of monochromatic surface wave, the wave-induced viscosity and diffusivity are functions of the Stokes drift. The influence of the wave-induced mixing scheme on global ocean circulation models was tested with the Princeton Ocean Model, indicating significant improvement in upper ocean thermal structure and mixed layer depth compared with mixing obtained by the Mellor–Yamada scheme without the wave influence. For example, the model–observation correlation coefficient of the upper 100-m temperature along 35° N increases from 0.68 without wave influence to 0.93 with wave influence. The wave-induced Reynolds stress can reach up to about 5% of the wind stress in high latitudes, and drive 2–3 Sv transport in the global ocean in the form of mesoscale eddies with diameter of 500–1,000 km. The surface wave-induced mixing is more pronounced in middle and high latitudes during the summer in the Northern Hemisphere and in middle latitudes in the Southern Hemisphere.     

Removal of Ni(II) from Aqueous Solutions by Nanoscale Magnetite

Magnetite nanoparticles were applied to remove Ni(II) from aqueous solutions as a function of pH, contact time, supporting electrolyte concentration, and analytical initial Ni(II) concentration. The highly crystalline nature of the magnetite structure with diameter of around 10 nm was characterized with transmission electron microscopy (TEM) and X‐ray diffractometry (XRD). The surface area was determined to be 115.3 m²/g. Surface chemical properties of magnetite at 25°C in aqueous suspensions were investigated. The point of zero charge (pHzpc) was found to be 7.33 and the intrinsic acidity constants (${\rm p}K_{{\rm a}1}^{{\rm s}} $ and ${\rm p}K_{{\rm a}2}^{{\rm s}} $ ) were found to be 9.3 and 5.9, respectively. The surface functional groups were investigated with Fourier transform‐infrared spectroscopy (FTIR) as well. Batch experiments were carried out to determine the adsorption kinetics and mechanism of Ni(II) by these magnetite nanoparticles. The adsorption process was found to be pH dependent. In NaCl solutions, Ni(II) adsorption increased with increasing ionic strength while in NaClO₄ solutions, Ni(II) adsorption exhibited little dependence on the ionic strength of the solution. The adsorption process better followed the pseudo‐second order equation and Freundlich isotherm.     

基于规则库的三维空间数据模型

三维空间对象的形式复杂多样,对象之间的空间关系尚未形成共识.三维空间数据模型的空间及非空间关系的表达更是难以统一.典型的三维空间数据模型包括面向实体型、面向关系型和混合型3种数据模型,但这些模型存在诸如拓扑操作困难、对象语义描述不完整、关系表达欠缺等一系列不足.通过分析、综合3种模型的优缺点,以顾及拓扑面向实体的三维矢量数据模型为基础,设计了基于规则库的三维空间数据模型.这是一个将关系与对象相统一的新型数据模型.通过对对象关系的分析研究,引入规则的概念,进而构建出规则库,提出对空间对象间关系和结构统一的,完整的表达和管理方式.结合地质、矿山等应用将该三维空间数据模型在多个城市的三维地质应用中进行成功验证.通过应用,说明该模型实现了空间对象的自身结构和对象之间关系的统一表达,具备自定义、可扩展的空间对象关系表达能力,能够适应复杂应用要求,具有良好的应用前景.