Effects of stand types on recreational preferences of society in the Sub-Alpine Zone,northern Turkey

The main objective of this study was to examine how different stand types influenced the tendency of visitors for varying recreational activities(i.e., hiking, trekking, camping and hunting) from 1993 to 2018 in the surrounding areas of Uluyayla Natural Recreation Site in Bart1n, northern Turkey. A total of 627 visitors were selected on a voluntary basis,and questioned in the form of questionnaire. Most of the participants were in the age of 21-40 years old,and they were mostly(62.4%) male. Most...     

基于小波变换的三江平原低湿地井灌区年降水序列变化趋势分析

近年来,由于水田面积迅速增加,导致三江平原低湿地井灌水稻区地下水位普遍下降,"吊泵"、局部超采现象时有发生,因此,三江平原的地下水资源平衡急需恢复。为解决上述问题,以853农场为例,应用小波理论对853农场实测年降水时间序列的多时间尺度变化特征及突变特征进行分析,揭示该区年降水变化的主要周期及旱涝变化趋势,为853农场乃至整个三江平原充分利用天然降水、地下水资源恢复及可持续利用提供科学依据。     

鸟的迁徙图

鸟类是造物主作品中最美的精灵之一,曾经有多少人垂涎它们靓丽的羽毛,用来装饰自己的帽子,又有人至今还对这种美味趋之若鹜.鸟类生活在人类周围,它们跳跃翱翔,千姿百态,从早到晚,用歌声调剂着环境的枯燥与单调. 在城市里,我们对它们居住何处知之甚少,倒是夜巡的流浪猫们最喜欢掏鸟窝.当人们想亲近鸟类时,它们又毫不含糊地跳开或飞走...     

PRELIMINARY STUDY ON THE INFLUENCE OF FY-4 LIGHTNING DATA ASSIMILATION ON PRECIPITATION PREDICTIONS

Data from the lightning mapping imager on board the Fengyun-4 meteorological satellite (FY-4) were used to study the assimilation of lightning data and its influence on precipitation predictions. We first conducted a quality control check on the events observed by the first Fengyun-4 satellite (FY-4A) lightning mapping imager, after which the noise points were removed from the lightning distribution. The subsequent distribution was more consistent with the spatial distribution and range of ground-based observations and precipitation. We selected the radar reflectivity, which was closely related to the lightning frequency, as the parameter to assimilate the lightning data and utilized a large sample of lightning frequency and radar reflectivity data from the eastern United States provided by Vaisala. Based on statistical analysis, we found the empirical relationship between the lightning frequency and radar reflectivity and established a look-up table between them. We converted the lightning event data into radar reflectivity data and found that the converted reflectivity and composite reflectivity of ground-based radar observations showed high consistency. We further assimilated the lightning data into the model, adjusted the model cloud analysis process and adjusted the model hydrometeor field by using the lightning data. A rainstorm weather process that occurred on August 8, 2017, in south China was used for the numerical forecast experiment, and three experiments were designed for comparison and analysis: a control experiment, an experiment without the assimilation of FY-4 lightning data (NoLig), and an experiment with the assimilation of FY-4 lightning data (Lig). The results show that after assimilating the FY-4A lightning data, the accuracies of the intensity, central location and range of the precipitation predicted by the Lig experiment were obviously superior to those predicted by the control and NoLig experiments, and the effect was especially obvious in the short-term (1–2 hour) forecast. The studies in this paper highlight the application value and potential of FY-4 lightning data in precipitation predictions.     

塔中秋冬季大气稳定度频率分布

采用温度梯度法、理查逊数法、总体理查逊数法分别分析塔中地区秋、冬季的大气稳定度的差异以及大气稳定度的分布频率特征.结果表明:不同的方法对大气稳定度的计算结果有很大影响,采用Ri法和BRi法能够较好的反映塔中秋冬季大气稳定度的变化;塔中秋、冬季大气层结以稳定层结为主,不稳定层结出现频率次之,中性层结出现的频率最小;秋季、冬季稳定度频率有一定差异,秋季中性层结、稳定层结频率小于冬季,不稳定层结大于冬季.     

50米天线馈源焦点偏移补偿控制系统的设计

通过测量北京密云50m天线在不同俯仰角度下X波段馈源的焦点轴向偏移,拟合出了由于天线重力形变引起的X波段馈源的焦点轴向偏移曲线.为了补偿焦点偏移,设计了包含电流环、转速环和位置环的馈源控制系统,并基于Matlab/Simulink软件,对系统进行了仿真.仿真结果表明,本文设计的馈源控制系统能够补偿焦点偏移,且系统具有良好的动态和稳态性能.     

基于随机理论的Nash汇流模型初探

在Nash模型中引入随机微分方程理论,分别假定模型具有随机输入和随机参数的情况,对汇流过程的随机性进行了分析和探讨,并将随机汇流模型应用到沿渡河流域,取得了满意的效果.在Nash模型中引入随机理论,不仅可以给出汇流系统输出的数学期望,而且可以同时给出输出的均方差.这样就能够正确地反映出随机性因素对汇流过程的影响.     

A New Species Group in the Genus Tanytarsus van der Wulp(Diptera:Chironomidae)Based on a Fossil Record from Baltic Amber

<正>A new fossil chironomid,Tanytarsus serafini,found in Baltic amber is described and illustrated based on adult males.The new species and similar extant species of the genus Tanytarsus van der Wulp are compared. Due to several distinct characters of wing,legs and hypopygium,a new species group for Tanytarsus serafini is proposed,and its diagnostic features are evaluated.     

Fossil Hydrophilid Beetles (Coleoptera: Hydrophilidae) of the Late Oligocene Rott Formation (Germany)

<正>Fossil water scavenger beetles(Coleoptera:Hydrophilidae)of the latest Oligocene Rott Formation are revised,based on the examination of the type specimens,as well as numerous additional material from Statz(Los Angeles)and Kastenholz(Bonn)collections.Seven hydrophilid species are recognized,five of which are reliably attributed to the following genera:Berosus morticinus(von Heyden and von Heyden,1866),Paracymus excitatus (von Heyden and von Heyden,1866),Paracymus sp.,Hydrobiomorpha fraterna(von Heyden,1859),and Hydrophilus rottensis(Statz,1939).Coccinella? protogaeae Germar 1837 is attributed to the subtribe Hydrophilina, and Cymbiodyta? austera Statz 1939 to the subfamily Hydrophilinae.Hydrous ebeninus Statz 1939 and Paracymus excitatus(form 3)are excluded from the Hydrophiloidea.Berosus capitatus Statz 1939 is synonymized with Berosus morticinus,and Hydrous neptunus von Heyden and von Heyden 1866 with Hydrobiomorpha fraterna.Lectotypes of Philydrus morticinus von Heyden and von Heyden 1866 and Hydrous ebeninus Statz 1939 are designated.The significance of the hydrophilid fossils for paleoecological reconstructions of the former Rott Lake is briefly discussed.