南海资源环境地理研究综述

南海及沿岸地带是亚太地区经济发展最有活力和潜力的地区之一,受全球变化和人类活动的影响,南海资源环境正发生快速变化,对社会、经济、生态和环境带来新压力。本文从地理空间信息角度,以海岸资源、海洋资源和珊瑚礁资源的地理研究为综述内容,梳理了该区域岸线遥感监测、油气资源储量及渔业资源渔获量的地理差异、珊瑚礁地貌遥感监测与珊瑚白化等相关研究进展,讨论了已有研究的成果及其薄弱方向,依据发展趋势探讨了未来研究工作的重点。综述发现,南海资源环境的地理空间研究中,主要成果表现在资源环境的大面积快速监测与地理分异性方面,但在资源分布的内在机制及资源开发的环境效应影响方面仍缺少足够的研究。未来可望获得突破的研究主要包括：区域时空多尺度特征及其效应,区域间自然和社会发展的分异和规律,多源数据融合的南海资源动态监测的精度与时效的提高,以及资源变化过程的海洋生态与环境综合效应研究等。     

基于模糊自整定PID的直升机飞行控制律设计

在经典PID控制律基础上,引入模糊控制的概念设计模糊自整定PID控制律改进无人直升机姿态回路控制器,实现了PID控制器的参数在线自整定,并改善了控制器性能.通过Matlab对闭环系统进行算法仿真,表明模糊自整定PID控制器能够发挥优于传统PID控制器的控制性能.最后对所设计的控制器进行半物理仿真验证,通过对比典型输入指令下经典PID和模糊自整定PID两种控制器的控制效果,验证了模糊自整定PID对系统性能的优化.     

基于鲁棒自适应策略的燃气轮机系统控制器设计

太阳能、风能和潮汐能等可再生能源的发电系统,具有间歇性发电的特性.因此,具有快速响应、发电效率高的燃气轮机发电系统,能够在可再生能源发电间歇出现时充当替代系统,不仅稳固电网的负荷能力,还有助于推动可再生能源的发展.由于燃气轮机是一个模型包含未知的复杂非线性系统,目前针对转速环节主要采取传统PID控制技术.然而,实际运行中系统工况发生变化时,控制器参数不能随着这些变化做出相应的调整,使得控制效果欠佳,执行器故障的出现也可能导致系统无法正常工作.因而,本文针对单轴燃气轮机的孤岛发电模式,结合燃气轮机系统特性,基于反步法的设计思路,引入不依赖于系统模型的鲁棒自适应控制策略,并加入容错控制和Nussbaum函数构造转速控制器.在控制器设计过程中融合动态面方法,解决高阶系统中反步法引起的计算爆炸问题.最后,通过仿真,验证了控制器的可靠性.     

利用WRF-NAQPMS模拟土地利用变化对武汉城市灰霾天气的影响

城市化极大地改变了城市下垫面的性质,这有可能增加灰霾天气发生的概率和强度.利用Landsat-7 ETM+和HJ-1A卫星多光谱遥感数据,通过人工解译获得2002年和2012年武汉市土地利用情况,并对武汉市土地利用规划图进行数字化和尺度转换.在此基础上,针对武汉市典型灰霾天气过程,对不同土地类型（历史、现状和规划）利用WRF-NAQPMS空气质量数值模式进行了不同情景的模拟.同时,对比分析和揭示了不同情境下,大气风场和主要大气污染物浓度场的变化,解析了下垫面对灰霾天气的影响.可为从灰霾天气防治的角度完善城市土地规划和建设提供科学依据.     

Regional Frequency Analysis of Observed Sub-Daily Rainfall Maxima over Eastern China

Based on hourly rainfall observational data from 442 stations during 1960–2014, a regional frequency analysis of the annual maxima(AM) sub-daily rainfall series(1-, 2-, 3-, 6-, 12-, and 24-h rainfall, using a moving window approach) for eastern China was conducted. Eastern China was divided into 13 homogeneous regions: Northeast(NE1, NE2), Central(C), Central North(CN1, CN2), Central East(CE1, CE2, CE3), Southeast(SE1, SE2, SE3, SE4), and Southwest(SW).The generalized extreme value performed best for the AM series in regions NE, C, CN2, CE1, CE2, SE2, and SW, and the generalized logistic distribution was appropriate in the other regions. Maximum return levels were in the SE4 region, with value ranges of 80–270 mm(1-h to 24-h rainfall) and 108–390 mm(1-h to 24-h rainfall) for 20- and 100 yr, respectively.Minimum return levels were in the CN1 and NE1 regions, with values of 37–104 mm and 53–140 mm for 20 and 100 yr,respectively. Comparing return levels using the optimal and commonly used Pearson-III distribution, the mean return-level differences in eastern China for 1–24-h rainfall varied from-3–4 mm to-23–11 mm(-10%–10%) for 20-yr events, reaching-6–26 mm(-10%–30%) and-10–133 mm(-10%–90%) for 100-yr events. In view of the large differences in estimated return levels, more attention should be given to frequency analysis of sub-daily rainfall over China, for improved water management and disaster reduction.     

2021-04-16河北滦州MS4.3地震前的大气电场异常信号分析

中国科学院国家空间科学中心分布在天津市宝坻区和廊坊市永清县的2个观测台站在2021-04-16河北滦州M_S4.3地震前均观测到大气电场异常。宝坻站监测到过境云与地质活动混合型电场异常信号;永清站监测到湾型持续电场异常信号,属于典型的临震前小时尺度先兆信号,其幅度和持续时间均明显高于宝坻站的异常电场信号。对比电场异常期间2个台站的气象活动和空间天气活动发现,虽然2台站电场异常信号的表现方式不同,但背景变化中均隐含大型地质活动信号。分析结果表明,未来可通过分析多源活动导致的空间静电演变过程,形成有效的识别方法,在一定的气象活动范围内,从大气静电监测数据中提取中等以上强度地震的前兆信息。     

Production of Pacific White Shrimp Polycultured with Swimming Crab at Different Densities,and Nutrient Budget in the Enclosure System

This study was to evaluate the effect of stocking densities on the nitrogen and phosphorus budgets for a polyculture of the crab Portunus trituberculatus and the Pacific white shrimp Litopenaeus vannamei.The shrimps(initial weight,0.012 g)were cultured at a density of 45 shrimp m^-2,and juvenile crabs(initial weight,0.024 g)were cultured at five densities of 0,3,6,9,and 12 crabs m^-2.The treatments were grouped as C0S45,C3S45,C6S45,C9S45,and C12S45,respectively.Water quality parameters,growth of shrimp and crabs,and nitrogen and phosphorus budget were measured.The results indicated that the shrimp performances in polyculture treatments C3S45 and C6S45 were superior to those in the crab-free treatment(C0S45).The crab in treatments C3S45 and C6S45 exhibited a significantly higher final mean weight and carapace width/length than those in treatments C9S45 and C12S45.The final size and survival of crabs had a negative correlation with the increasing crab stocking density.The contents of total phos-phorus and total nitrogen and the comprehensive contamination index values were higher in the C9S45 and C12S45 treatments than in the other treatments.The conversion ratios of nitrogen for crab and shrimp growth in treatment C3S45 were significantly higher than those in the crab-free treatment.These findings indicate that polyculturing shrimp with crabs at suitable densities can improve productivity,profitability,nutrient utilization,and the environmental quality.From the 60-day treatments,the optimal culture densi-ties were 3-6 crabs m^-2 and 45 shrimps m^-2.     

Effect of Penetration Rates on the Piezocone Penetration Test in the Yellow River Delta Silt

Partial drainage often occurs during piezocone penetration testing on Yellow River Delta silt because of its intermediate physical and mechanical properties between those of sand and clay.Yet,there is no accurate understanding for the range of penetra-tion rates to trigger the partial drainage of silt soils.In order to fully investigate cone penetration rate effects under partial drainage condi-tions,indoor 1 g penetration model tests and numerical simulations of cavity expansion at variable penetration rates were carried out on the Yellow River Delta silt.The boundary effect of the model tests and the variation of key parameters at the different cavity ex-pansion rates were analyzed.The 1 g penetration model test results and numerical simulations results consistently indicated that the penetration rate to trigger the partially drainage of typical silt varied at least three orders of magnitude.The numerical simulations also provide the reference values for the penetration resistance corresponding to zero dilation and zero viscosity at any given normalized penetration rate for silt in Yellow River Delta.These geotechnical properties can be used for the design of offshore platforms in Yel-low River Delta,and the understanding of cone penetration rate effects under the partially drained conditions would provide some technical support for geohazard evaluation of offshore platforms.     

太阳多极活动区中的磁重联、剪切低磁弧内的强电流和冕穴结构

探讨了复杂磁结构上空日冕物理状态与磁剪切的关系．结果表明在强磁场的磁中性线上方磁剪切会引起具有强电流和较强等离子体压力的低磁弧．这可解释Ｙｏｈｋｏｈ 卫星的观测结果     

黄海潮生陆架锋的数值模拟研究

采用海洋三维热结构及环流模式,模拟了黄海在Ｍ２潮流混合作用下,夏季温度的分布和变化特征。从数值研究的角度,对黄海陆架水域的海洋锋现象,诸如苏北浅滩外、山东半岛东端、大连、木浦水域的锋面以及锋面沿岸一侧的表层冷水区的成因及分布进行了探讨,模拟结果再现了黄海陆架锋的潮生性质。