基于北斗船位数据的渔业信息解译与应用研究——以中国毛虾限额捕捞管理为例

2020年6月15日—7月15日,我国首次中国毛虾(Acetes chinensis)限额捕捞试点于江苏连云港实施。本研究提取62艘毛虾网船在限额捕捞期间的421700条北斗船位数据经纬度、航速、航向等信息,运用缓冲区叠加分析法、DBSCAN密度聚类算法、平均中心算法、核密度估计以及数据库查询对捕捞努力量等管控要素进行分析研究。结果显示,所有毛虾网船累计作业239个航次、1942个网次,捕捞过程分为航行、抛锚布网、等待渔获、收渔获、停航等5个状态,中国毛虾捕捞状态船位点呈直线分布,总捕捞时长为4413.73h,82.4%的单网次捕捞时长为1.5—3.5h,各网次捕捞产量呈现多核心空间分布模式,总捕捞努力量为108106343 m²·h,计算62艘的捕捞总产量值约为2328 t,比上报产量高12.6%;本文通过北斗船位数据解译和提取捕捞努力量以计算中国毛虾捕捞产量及资源空间分布情况,有效应用于中国毛虾限额捕捞,为解决我国单品种限额捕捞难点积累了宝贵经验。     

低屈服点钢研究进展与力学性能数据分析

为对低屈服点钢进行进一步的研究,同时促进其在工程中的应用,全面综述了国内外学者对低屈服点钢材料的研究成果,主要包括单调拉伸性能、循环加载性能以及低屈服点钢材料的应用。并将文献中的力学性能参数进行统计,采用K-S检验法对屈服强度与抗拉强度进行检验。结果表明:低屈服点钢具有良好的延性与滞回性能,力学性能参数基本满足规范要求;3种钢材的伸长率均随厚度增大而增大;低屈服点钢屈服强度符合正态分布,抗拉强度则不符合正态分布;实际工程中对低屈服点钢耗能构件的应用仍相对较少,还需进一步对其进行深入研究,以提高其应用比例。     

Numerical study of the biaxial compressive strength of high strength concrete based on a yield design micromechanical approach

This paper presents a numerical study of high strength concrete microstructure effects on its uniaxial and biaxial compressive strengths. Concrete is first represented as a set of angular aggregates interacting within a cement paste matrix. Then, a yield design kinematic approach is conducted at the mesoscopic scale in order to determine the concrete compressive strength for a given loading path. The proposed model, having a low computational cost, is able to capture the main microstructure effects already observed in literature on concrete uniaxial compressive strength, in particular, the aggregates volume fraction and maximal size effects. Finally, the proposed model also predicts the biaxial failure envelope of high strength concrete and confirms some experimental trends observed in literature.     

Sediment yield and transport process assessment from reservoir monitoring in a semi‐arid mountainous river

Soil loss, fluvial erosion, and sedimentation are major problems in semi‐arid environments due to the high associated costs of decreasing services such as provisioning and regulating water resources. The objective of this research is to analyse sediment yield in a mountainous semi‐arid basin, paying special attention to the sources of sediment, the associated uncertainties, and the transport processes involved. The segregation hypothesis along a reservoir of the sediment coming from hillslopes or fluvial systems is also evaluated. For this purpose, bottom‐set and deltaic deposits of a reservoir (110 hm³ ) in southern Spain have been measured and compared with basin erosion and fluvial transport monitoring over a 12‐year period. The volume of sediment stored at the bottomset of the reservoir shows a relative match with parametric predictions based on the Revised Universal Soil Loss Equation/Modified Universal Soil Loss Equation hillslope models and rating curves, estimated as being between 7 and 13 t·ha^?1·year^?1. Similarly, the measured volume of deltaic deposit fits the average value of stochastic simulations from different bedload transport equations. These contributions represent 50–65% of the total volume measured regarding suspended sediment inputs, way above that described in previous works. This highlights the importance of considering bedload when estimating the useful life of reservoirs in semi‐arid environments. The major differences in sediment grain size between hillslopes and river systems, and the size fractions measured along the reservoir, support the assertion of segregation hypothesis. Nonetheless, based on the processes observed and the uncertainty related to modelling, that assertion has to be taken with caution. At basin scale, a specific sediment yield of between 19 and 24 t·ha^?1·year^?1 has been estimated, which includes hillslopes and fluvial contributions. This rate is in the range of sediment yield reported for Mediterranean mountain areas of a torrential character. The pulse‐like nature of the system and the spatial heterogeneity of fluvial and hillslope erosion rates points out the importance of considering mid to long‐term and process‐based approaches and emphasizes the limitations of annual estimations for management purposes.     

Simulating the Impacts of Global Warming on Wheat in China Using a Large Area Crop Model

Temperature is one of the most prominent environmental factors that determine plant growth,development, and yield.Cool and moist conditions are most favorable for wheat.Wheat is likely to be highly vulnerable to further warming because currently the temperature is already close to or above optimum.In this study,the impacts of warming and extreme high temperature stress on wheat yield over China were investigated by using the general large area model(GLAM) for annual crops.The results showed that each 1℃r...     

地面气象观测数据文件的全程质量控制

利用山西省1983年-2006年暴雨洪涝、干旱、冰雹、霜冻、连阴雨等气象灾害受灾面积资料和农作物产量资料,采用灰色关联分析方法,对山西省主要气象灾害对农业的危害大小进行了分析。结果表明,影响山西农作物产量最严重的4种气象灾害依次是干旱、暴雨洪涝、冰雹和霜冻。     

栽培条件下甘草的甘草酸及多糖含量

通过对3年生相同人工栽培条件下的不同种甘草及2种不同栽培措施的乌拉尔甘草为分析样本,采用高效液相色谱和苯酚-硫酸比色法对其甘草酸及多糖含量进行测定,分析比较甘草酸与甘草多糖含量之间的相互关系,并筛选出乌拉尔甘草的最优栽培措施。结果表明：甘草酸含量顺序为乌拉尔甘草〉胀果甘草〉黄甘草〉光果甘草;多糖含量以光果甘草3．76％为最高,其余3个种间含量相差不大。正交试验的方差分析表明：（1）对于播种3年生乌拉尔甘草,以甘草酸含量为评价指标,最优栽培措施为：灌溉量4500m^3／hm^2、二铵0kg／hm^2、种子（对照）、尿素0 kg/hm^2、播种量90kg/hm^2;若以甘草多糖含量为获取目标,最优栽培措施为：灌溉量1500m^3／hm^2、二铵300kg/hm^2、种子（包衣,尿素0．5％浸泡24h）、尿素300kg／hm^2、播种量90kg/hm^2。（2）对于移栽3年生乌拉尔甘草,以甘草酸含量为评价指标,最优栽培措施为：灌溉量1500m^3／hm^2、移栽苗（对照）处理、二铵0 kg／hm^2、尿素0kg/hm^2、株距5cm;若以甘草多糖含量为评价指标,最优栽培措施为灌溉量3000m^3／hm^2、移栽苗（对照）处理、二铵150kg／hm^2、尿素300kg／hm^2、株距10cm。     

水氮耦合对膜下滴灌棉花产量效应的探讨

为了探讨膜下滴灌棉花水肥耦合效应,于2003-2004年在新疆北疆雨水较少地区开展不同水氮条件对棉花产量效应的大田试验研究。结果表明,在该试验条件下,土壤水分对产量的作用最大,氮肥次之;水氮耦合的产量效应表现为适宜土壤水分中施肥量效果最高,高土壤水分中施肥量次之,低土壤水分低施氮量最低;水氮交互大小的顺序是水氮耦合＞土壤水分＞施氮量;获得最高籽棉产量5253kg/hm2的灌水量为4190m3/hm2,施氮量为276kg/hm2。     

坎上铁矿水文地质特征及涌水量预测

在水文地质勘查的基础上,指出坎上铁矿分成南北2个矿段,赋存于复杂的水文地质条件中,包括4个含水层和2个弱透水层。利用大井法和数值模拟法对矿区的涌水量进行预测,结果表明本阶段概算单独开采至矿体底板时,北矿段正常涌水量为3 067m3/d,南矿段正常涌水量为23 400m3/d。     

峰峰矿区大淑村矿水文地质条件探析

大淑村井田周边赋存的断层均为倾向井田外侧的正断层,致使井田部位相对抬升,切断了含水层的补给来源,地下水补给、排泄不良,井田处于相对封闭的水文地质单元之中。井田内开采上组煤的主要充水含水层为大煤顶板砂岩含水层,次为野青灰岩和伏青灰岩含水层;煤层回采冒落后,下石盒子组底部砂岩含水层将成为间接充水含水层。这些含水层的富水性弱,单位涌水量均小于0．05L／（s·m）,因此,大淑村井田开采上煤组的矿井水文地质类型为中等,矿井受水害的影响不大,矿井防治水的工作简便易行。