Analysis of ALOS PALSAR InSAR data for mapping water level changes in Yellow River Delta wetlands

Wetlands play a key role in regional and global environments and are critically linked to many major issues such as climate change, water quality, hydrological and carbon cycles, and wildlife habitat and biodiversity. It is very important to measure water level changes and consequently water storage capacity changes in wetlands to enable wetland protection and reconstruction. In this study, HH polarization L-band synthetic aperture radar (SAR) data were used in conjunction with synchronous field measurements and investigations to investigate the potential to detect water level changes under different types of wetlands. After evaluating factors that influence interferometric coherence, the framework for measuring water level changes using interferometric synthetic aperture radar (InSAR) phase information is presented in this article. Additionally, the SAR data obtained are used to investigate InSAR-derived water level changes in Yellow River Delta wetlands. The results show that InSAR technology has great potential for application in mapping water level changes in coastal wetlands, and InSAR-derived water level changes can supply unprecedented spatial details.     

迭代集合卡尔曼滤波方法的性能比较研究

针对数据同化过程中模型的非线性问题,通过分析对比得出了一种适合强非线性系统的迭代集合Kalman滤波(IEnKF)。在Lorenz\|63模型的框架内,比较分析集合Kalman滤波(EnKF)、迭代集合Kalman滤波(IEnKF)和迭代扩展卡Kalman滤波(IEKF)在集合数、观测误差方差、放大因子和模型步长不同时同化性能差异,由此探讨这3种方法的优劣。研究结果表明:随着集合数的增加,3种算法的同化性能都得到了一定的改善;放大因子的增大,使其同化性能变差且EnKF呈现出多重波峰波谷的现象;3种方法的均方误差(RMSE）随观测误差方差和模型步长的增大而增大,其同化精度都变差;而IEnKF同化性能最优,更具有鲁棒性。     

数字喷泉码及网络喷泉码的最新进展

数字喷泉码和网络编码都是提高网络传输效率的有效技术方法,两者的有机结合形成的网络喷泉码具有重要的理论意义和应用价值。本文首先对数字喷泉码的最新研究进展进行了综述,分别介绍了几类常见的数字喷泉码的相关研究工作;其次对当前网络喷泉码的研究现状进行了系统的总结,重点介绍了同构网络喷泉码、异构网络喷泉码和无线网络喷泉码的相关理论及其最新研究成果,并分析了研究中存在的问题;最后对网络喷泉码的相关理论及其应用的发展趋势进行了分析和展望。     

Fabrication of Magnetic Fe3O4 Nanotubes by Electrospinning

利用静电纺丝法制备复合纤维前躯体,将前躯体烧结、还原后成功得到了Fe3O4纳米管。研究了电纺工艺参数(PVA浓度、电压、接收距离)对复合纤维前躯体的影响。采用XRD、SEM、TEM等手段对纳米管的物相、形貌进行表征,同时通过改变烧结工艺研究了Fe3O4纳米管的形成机理,并且研究了Fe3O4纳米管的磁性能。结果表明:纳米管均匀、连续,外径和内径分别大约为100和50 nm;Fe3O4纳米管的磁饱和强度、矫顽力和剩磁强度分别为54.2 A·m2/kg,215×79.6 A/m和12.8 A·m2/kg。     

城市大型住区地下车库设计中的视觉识别问题

视觉识别设计属于视觉传达和环境艺术设计的交叉学科,城市住宅小区的地下车库越来越庞大,人们在大型地下车库中往往不能分辨方向,识别困难,使用不便,已经成为住区大型地下车库的症结所在,迫切需要引入视觉识别导向的设计理念从空间设计入手改善地下车库的空间状态。     

Investigation on carbon nanotube oxide for anhydrous proton exchange membranes application

The widespread participation of polymers in the membrane preparation has been considering to be critical for the development of proton exchange membranes (PEMs). For the polymers without functional groups to conduct protons, the introduction of proton conduction carriers with the formation of composite membranes is an effective strategy to prepare PEMs with the outstanding proton conductivity. However, there remains a potential risk of the components leaking from composite membranes due to the lack of the interaction force. Here, the composite of carbon nanotube oxide (OCNT) assembling with cadmium telluride (CdTe) and 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF₆) was introduced into the system of phosphoric acid (PA) doping poly(vinylidene fluoride) (PVDF) with the formation of PVDF/OCNT-CdTe-bmimPF₆/85%PA membranes. PA molecules are anchored by the inorganics of OCNT-CdTe-bmimPF₆ and are stabilized in membranes. The high and stable proton conductivity values at the elevated temperature are obtained comparing the reported PVDF/bmimPF₆/PA membranes. Specifically, the proton conductivity value reached 1.28 × 10⁻¹ S/cm at 160 °C and the value is stable 1.70 × 10⁻² S/cm at 120 °C lasting for 350 h. The fine stability in components could make the membranes extricate from the predicament of proton conductivity decline exceeding 120 °C under anhydrous conditions in PVDF/bmimPF₆/PA membranes. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48833.     

多旋回盆地复杂生烃史条件下烃源岩生烃量研究

通过热模拟实验的方法,探讨了复杂生烃史条件下烃源岩生烃量的变化特征。热模拟实验结果表明,复杂生烃史条件下,烃源岩的生烃量与简单连续生烃相比并不相同。烃源岩两次不连续累计生烃量大于连续生烃量;不同的两次不连续生烃中,烃源岩累计生烃量也不相同。对热模拟实验结果的讨论认为,不连续生烃量与连续生烃量的差别主要反映了生烃过程、排烃条件以及可能存在的外界环境的影响。多旋回盆地中的古老烃源岩,在漫长而复杂的生烃过程中,其生烃量与简单的连续生烃相比可能存在显著差异。     

360安全卫士注册表保护原理及突破

介绍了360安全卫士注册表保护原理,以此得到针对计时器的突破思路,同时简述实际开发中遇到问题及解决方案。     

A new (3,4,7)-connected topology framework based on [Cd2(CO2)3O4N2] second building unit

A new 3D coordination polymer [Cd₂(L³)(BTC)(H₂O)] (1) (HL³ = 3,5-bis(pyridin-3-ylmethoxy)benzoic acid, H₃BTC = 1,3,5-benzenetricarboxylic acid), has been isolated under hydrothermal condition and characterized by single-crystal X-ray diffraction. Compound 1 is constructed from Cd₂-based second building units (SBUs) [Cd₂(CO₂)₃O₄N₂] and displays a 3D (3,4,7)-connected net with (4²·6)(4³·6³)(4⁵·6¹¹·8⁵) topology. In addition, the photoluminescent spectra indicate compound 1 may be a good candidate for blue-luminescent materials.     

典型烃类分子裂解产物分布数值模拟

利用烃类蒸汽热裂解二维工艺数学模型,选择二维模型原料分子中13种典型烃类分子,通过数学模拟考察烃类分子结构和裂解温度对热裂解产物的影响.结果表明:正构烷烃裂解产物中乙烯收率明显大于异构烷烃,且乙烯收率随着烷烃碳数的增加逐渐增加;异构烷烃裂解产物中丙烯收率大于同碳数的正构烷烃,且丙烯收率随碳数增大而显著减少;异构烷烃裂解...