Impacts of sampling design on the abundance estimation of Portunus trituberculatus using crab pots

Fishery-independent surveys can provide high-quality data and support fishery assessment and management.Optimization of sampling design is crucial to increase the quality of fishery surveys.Crab pots are important fishing gears used to catch crabs.We analyzed the impacts of sampling design of crab pots on the abundance of Portunus trituberculatus in the Changjiang(Yangtze)River estuary to the Hangzhou Bay and its adjacent waters in East China Sea.The crab pots were cylindrical,240 mm in height and 600 mm in diameter of the iron ring.Our sampling designs(including fixed-station sampling,simple random sampling,stratified fixed-station sampling,and stratified random sampling),three number of stations(9,16,and 24),and three numbers of crab pots(500,1000,and 3000)were simulated and compared with the“true”abundance that obtained from bottom trawl surveys in the study area in 2007.The scenarios with 16 stations were set in stratification as a control group for comparison with unstratified designs.Results show that simple random sampling can obtain more stable results than fixed-station sampling in the abundance estimation of P.trituberculatus.In addition,stratified sampling resulted in more accurate abundance than unstratified sampling.The accuracy of the simulated results improved with the increase of the number of stations.No remarkable differences in the results were found among the scenarios of different number of crab pots at each station.However,resource-intensive areas exerted great impacts on simulation results.Thus,prior information or pre-survey results about resource abundance and density distribution are necessary.This study may serve as a reference for future sampling designs of crab pots of P.trituberculatus and other species.

计算动态系统网格通量场的驿站重要抽样方法

对与时间有关输运问题计算条件下,全系统不同网格体通量计算统计涨落较大,甚至个别网格很难得到计数的现象,提出驿站重要抽样方法.研究可以选择的重要性函数,给出抽样方法,推导重要性偏倚抽样的源粒子纠偏权重公式.经过推导证明连续多时间步抽样计算不存在粒子纠偏权发散问题.数值模拟结果表明,采用驿站重要抽样方法,全系统精细网格通量场计算精度基本一致,整体计算结果得到明显改善.

主从式多机通信中报警与时间校准的应用

叙述了主从式多机通信问题的解决,详细说明了报警上限修改的流程图,上位机管理站或者监测站均可以修改报警上限,对程序设计思路进行了详细分析与阐述,并给出了上位机管理站报警上限修改画面。对监测站的时间校准程序进行了设计。利用VB语言实现了时间校准程序上位机界面设计。给出了上位机管理站时间校准界面显示。对多个I/O口不同房间的传感器完成写报警上限到传感器的操作进行了程序设计。较好地实现了上位机管理站与监测站的数据通信与管理。

黄登水电站RCCD超长芯样相关技术问题探析

针对黄登水电站RCCD(碾压混凝土坝)质量检查过程中取出的24.6 m的碾压混凝土芯样,分析总结碾压混凝土施工技术和施工管理经验。结合混凝土配合比试验结果、施工规范的修订情况、层间结合技术、温控防裂技术和施工管理措施对超长芯样与混凝土各项性能及其相关技术问题进行探析,认为超长芯样的取得与混凝土原材料品质、配合比、混凝土拌合物均匀性和工作性、层间结合性能、力学性能、体积稳定性、抗裂性能和施工管理措施有着直接关系。说明黄登水电站RCCD施工过程中选用的混凝土原材料品质优良,配合比设计合理,拌合物质量均匀,混凝土工作性、层间结合性能、力学性能、抗裂性能良好,温控防裂及施工管理措施得当。