干旱对河西走廊植被净初级生产力的影响

干旱对生态系统碳循环具有重要影响,随着气候变暖,全球干旱事件频率不断上升,研究干旱对植被净初级生产力的影响具有重要意义.提高植被净初级生产力(NPP)的时间分辨率是认识干旱对其影响机制的重要途径.基于5天NDVI遥感数据,以河西走廊为研究区,利用CASA模型估算2010-2015年5天步长尺度的NPP,将5天降水为零定...     

钝缀锦蛤(Tapes dorsatus)稚贝的温度和盐度耐受性研究

本实验在室内控制条件下,采用实验生态学方法研究了钝缀锦蛤(Tapes dorsatus)稚贝对温度和盐度的耐受性.在温度耐受性方面:(1)稚贝在低温端温度为4℃、6℃、8℃、10℃时保持90％～100％存活的时间分别为0?d、2?d、3?d、7?d;在高温端温度为33℃、34℃、35℃、36℃时保持90％～100％存活...     

现行黄河口水下三角洲海底形貌及不稳定性

高分辨力的声学仪器调查表明,现行黄河口水下三角洲海底的形貌十分复杂,由于高浓度巨量黄河泥沙快速沉积的结果,使河口底坡出现了大量的不稳定性现象,如塌陷冲沟,高密度沉积物重力流,切割—充填结构海底,V形水下河谷、滑塌等。根据海底扰动程度作了分区,划分了地形单元,并对不同的海底形态的成因作了分析。比较了1985和1986年两个航次考查结果的变动,分析了原因。     

气候变化对典型气象年数据的影响及能耗评估——以中国北方大城市天津为例

本文以中国北方城市天津为例,采用Sandia及Danish两种方法生成典型气象年（TMY）数据,并借助TRNSYS软件模拟得到3个时段（1961-1990年、1971-2000年和1981-2010年）典型办公建筑的逐时负荷,评估气候变化对典型气象年数据及模拟负荷的影响。结果表明：Sandia和Danish生成典型气象年的方法在天津均有较好的适用性,Sandia方法采用6个气象要素生成的典型气象年数据代表性满足要求。受气候变化影响,典型气象年数据变化较大,采暖期（11月-翌年3月）较制冷期（6-9月）的变化更明显;从30年均值差异看,1981-2010年相对于1961-1990年,建筑供热负荷减少5.2%,而制冷负荷增加1.6%。因此,在使用典型气象年数据进行建筑设计能耗评估时需充分考虑气候变化的影响,加快典型气象年数据的生成和更新工作。基于天津现行使用的典型气象年数据模拟得到的办公建筑制冷负荷较1981-2010年偏低6.7%,供热负荷偏高4.7%。表明采用现行典型气象年数据进行建筑能耗评估时,会造成制冷负荷偏低,供热负荷偏高,从而降低人体舒适度及造成供热能源浪费。     

气候变暖有益于中国的社会和谐

中国传统农业的产量受气候控制,气候表现为冷暖和干湿交替的循环,因此农业产量也出现循环演变的规律,在冷期中生活资源的短缺所造成的生存压力,加剧了矛盾,促进了战争。而气候变暖可以缓解这些矛盾,因此,气候变暖有益于中国的社会和谐。     

基于3S技术的土地利用现状长效管理机制

本文介绍了上海市土地利用现状长效管理机制的构建思路、总体框架,及其发现——调查——处置——反馈机制。最后总结了上海市土地利用现状长效管理机制的作用和效果。     

The lithologic diversity of the Moon recorded in lunar meteorites Northwest Africa 7611 and 10480

Northwest Africa (NWA) 7611/10480 are lunar regolith breccia meteorites, composed of mineral fragments and various clasts including mare basalts, volcanic glasses, gabbroic lithologies, and a diverse variety of highland materials (ferroan anorthosite, Mg-suite, magnesian anorthosite, and alkali suite rocks) as well as different subvarieties of impact melt breccia. The Apollo two-component mixing model calculation reveals that the NWA 7611 source region contains 58 wt% mare materials and 42 wt% highland components, but the estimated mare components in NWA 10480 have a higher abundance (66 wt%). The predominantly very low-Ti (VLT) composition in both fine-grained basaltic and coarse-grained gabbroic lithologies indicates a provenance associated with a thick lava flow or a single magmatic system. The co-occurrence of zoning patterns and fine-scale exsolution lamellae in pyroxene debris supports a cryptomare deposit as the best candidate source. Phosphate Pb–Pb ages in matrix fragments, impact melt breccia, and basaltic clast indicate that the breccia NWA 7611 records geological events spanning approximately 4305–3769 Ma, which is consistent with the ages of ancient lunar VLT volcanism and the products of basin-forming impacts on the lunar nearside. The youngest reset age at ~3.2 Ga is potentially related to the strong shock lithification process of breccia NWA 7611. Moreover, the similar petrology, texture, geochemistry, cosmic-ray exposure data, and crystallization ages support that basaltic component in Yamato (Y)-793274, and Queen Alexandra Range (QUE) 94281, NWA 4884, and NWA 7611 clan came from the same basalt flow.     

长江中下游典型浅水湖泊表层水体微塑料时空分布特征——以湖北保安湖为例

以湖北保安湖为研究对象,分别于2021年4、7、10月和2022年1月采集表层水样,测定水体中微塑料丰度、粒径、形状、颜色和类型,探究浅水型湖泊表层水体中微塑料的时空分布特征及其影响因素。结果表明,保安湖表层水体微塑料的年平均丰度为(16.20±2.23)items/L。微塑料丰度呈现明显的季节性差异,其中夏季(采样时间7月)平均丰度最低,为(1.40±0.09)items/L。在所有微塑料颗粒中,粒径0.064～1 mm占比最大,为82.57%;黑色和无色微塑料占主导地位,占比分别为36.16%和21.31%;纤维状微塑料分布最广泛,占比达40.01%;聚乙烯(PE)和低密度聚乙烯(LDPE)是最主要的微塑料类型,两者之和占比达46.05%,其次为聚苯乙烯(PS,占比17.2%)、聚对苯二甲酸乙二醇酯(PET,占比8.33%)和聚乙酸乙酯(PVAC,占比8.31%)。统计分析表明,微塑料丰度与湖水水质无显著相关关系。该研究揭示了长江中下游地区典型浅水湖泊微塑料分布现状,为评估类似湖泊微塑料潜在污染风险提供了科学依据。     

COMPARATIVE STUDY ON RESIDENTS＇ PERCEPTION OF TOURISM IMPACT AT TOURIST PLACES—A Case Study of Xidi, Zhouzhuang and Jiuhua Mountain

Based on the questionnaire investigation, the authors make a comparative study on local residents‘ perception of tourism impacts in Xidi, Zhouzhuang and Jiuhua Mountain. The result shows that residents of the three places tend to have strong and consistent perception of its positive economic, socio-cultural and environmental impacts, but distinctly diverse ones of its negative impacts. Residents in Xidi and Zhouzhuang also have noticeable perception of its negative environmental impacts while those in Jiuhua Mountain have weaker perception of them.The research confirms the fact that residents are more liable to have positive perceptions at the early stage of the life cycle of the tourist places. The authors conclude that there exists a nonlinear relationship between residents‘ perception and tourism development stages, and that tourism socio-cultural impact may appear at an early stage of tourism development instead of being no universal.     

An assessment of fuzzy logic vessel path control

A fuzzy logic controller for ship path control in restricted waters is developed and evaluated. The controller uses inputs of heading, yaw rate, and lateral offset from the nominal track to produce a commanded rudder angle. Input variable fuzzification, fuzzy associative memory rules, and output set defuzzification are described. Two maneuvering situations are evaluated: track keeping along a specified path where linearized regulator control is valid; and larger maneuvers onto a specified path where nonlinear modeling and control are required. For the track keeping assessment, the controller is benchmarked against a conventional linear quadratic Gaussian (LQG) optimal controller and Kalman filter control system. The Kalman filter is used to produce the input state variable estimates for the fuzzy controller as well. An initial startup transient and regulator control performance with an external hydrodynamic disturbance are evaluated using linear model simulations of a crude oil tanker. A fully nonlinear maneuvering model for a smaller product tanker is used to assess the larger maneuvers