灰色稳健总体最小二乘估计及高铁路基变形预测     

陈洋  文鸿雁  覃辉  王清涛  周吕 《大地测量与地球动力学》2018,38(2):140-146

最小二乘估计和部分变量误差模型的总体最小二乘估计不具备抵御粗差的能力。鉴于粗差可能同时出现在灰色白化微分方程的观测值和系数矩阵中，本文提出基于IGGⅢ抗差方案的部分变量总体最小二乘稳健估计。结合仿真数据和高铁路基观测数据，系统地比较稳健最小二乘、部分变量总体最小二乘、本文算法参数估计结果和算法稳定性。结果表明，本文算法预测精度高，可以应用到高铁路基沉降预测中。  相似文献   

补肾生血方对肾性贫血大鼠EPO水平及EPOR mRNA的影响          下载免费PDF全文

范军  原洋  郭晓红 《应用海洋学学报》2018,34(4):138-141

目的：研究补肾生血方对肾性贫血大鼠促红细胞生成素（EPO）及EPOR mRNA水平的影响。方法：Wistar大鼠50只，分为对照组、模型组、中药组、EPO组、中药+EPO组，每组各10只，对除对照组外的其余组大鼠通过腺嘌呤灌胃制备肾性贫血大鼠模型，分别给予相应药物进行干预。分别于给药第2、8周观察血常规指标（Hb、RBC、HCT）、肾功能指标（BUN、Scr）的水平及EPO浓度，给药8周后处死大鼠，提取骨髓单个核细胞，测定EPOR mRNA表达量的变化。结果：与治疗2周相比，治疗8周中药组、EPO组、中药+EPO组大鼠的BUN、Scr显著降低，Hb、RBC、HCT、EPO水平及EPOR mRNA表达量显著上升，差异均有统计学意义（P＜0.05）。结论：补肾生血方具有改善肾性贫血模型大鼠肾功能、肾性贫血状况，其机制可能与提高骨髓有核细胞EPOR mRNA表达量，减轻毒素对EPOR的抑制，加强对内源性EPO反应性有关。  相似文献   

深水海底管道铺设安全辅助系统     

高爽  王法承  汤珂  李斌  李杨 《海洋工程》2018,36(2):127-134

此次研发的铺管安全辅助系统是一套自动化、简易化、旨在提高安装经济性和安全性的实时运行安全辅助系统,通过实时数据采集及处理,达到对安装期海管强度进行实时监测目的。系统组成包括设备系统和监测软件两部分。设备为系统提供辅助决策数据源;监测软件采用C++语言编写,用于数据接收、解析,并通过OrcaFlex API调用商业有限元软件OrcaFlex为分析内核进行实时分析计算,以可视化界面输出管道应力、应变、触地点等信息,给予船上作业人员安全指导,及时作出决策。  相似文献   

Vortex-Induced Vibrations of A Long Flexible Cylinder in Linear and Exponential Shear Flows     

Gao  Yun  Yang  Bin  Zou  Li  Zong  Zhi  Zhang  Zhuang-zhuang 《中国海洋工程》2019,33(1):44-56

A numerical study based on a wake oscillator model was conducted to determine the response performance of vortex-induced vibration(VIV) on a long flexible cylinder with pinned-pinned boundary conditions subjected to linear and exponential shear flows. The coupling equations of a structural vibration model and wake oscillator model were solved using a standard central finite difference method of the second order. The VIV response characteristics including the structural displacement, structural frequency, structural wavenumber, standing wave behavior,travelling wave behavior, structural velocity, lift force coefficient and transferred energy from the fluid to the structure with different flow profiles were compared. The numerical results show that the VIV displacement is a combination of standing waves and travelling waves. For linear shear flow, standing waves and travelling waves dominate the VIV response within the low-velocity and high-velocity zones, respectively. The negative values of the transferred energy only occur within the low-velocity zone. However, for exponential shear flow, travelling waves dominate the VIV response and the negative energy occurs along the entire length of the cylinder.  相似文献   

西太平洋海域现场培养实验中挥发性卤代烃浓度的变化及其影响因素     

韩钰  何真  刘珊珊  高旭旭  杨桂朋 《海洋学报》2020,42(2):1-9

CH₃I、CHCl₃、C₂HCl₃和CH₂Br₂是挥发性卤代烃4种重要成分，对大气化学产生重要影响。于2018年10月在西太平洋进行船基现场培养实验，研究微量元素Fe (50 nmol/L)、酸化(pH=7.9)、酸化(pH=7.9)和微量元素Fe (50 nmol/L)耦合作用、微量元素Fe (50 nmol/L)和N/P (16∶1)耦合作用及沙尘(4 mg/L)对浮游植物释放CH₃I、CHCl₃、C₂HCl₃和CH₂Br₂含量的影响。结果表明，与对照组相比，实验组CH₃I、C₂HCl₃和CH₂Br₂的释放均被不同程度抑制；CHCl₃的释放除添加沙尘时表现抑制作用外，其他条件下均为促进作用；实验组培养周期内叶绿素a浓度较高，而营养盐浓度变化规律不明显。总的来说，酸化和微量元素Fe可能是影响浮游植物释放挥发性卤代烃的重要限制因素，沙尘对促进浮游植物生长繁殖的影响更为显著。  相似文献   

Cryohydrology in Canada: A brief history     

Ming‐ko Woo 《水文研究》2019,33(26):3407-3411

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Re-examining urban region and inferring regional function based on spatial–temporal interaction     

Haiyan Tao  Keli Wang  Xuliang Li 《International Journal of Digital Earth》2019,12(3):293-310

Urban system is shaped by the interactions between different regions and regions planned by the government, then reshaped by human activities and residents’ needs. Understanding the changes of regional structure and dynamics of city function based on the residents’ movement demand are important to evaluate and adjust the planning and management of urban services and internal structures. This paper constructed a probabilistic factor model on the basis of probabilistic latent semantic analysis and tensor decomposition, for purpose of understanding the higher order interactive population mobility and its impact on urban structure changes. First, a four-dimensional tensor of time (T)?×?week (W)?×?origin (O)?×?destination (D) was constructed to identify the day-to-day activities in three time modes and weekly regularity of weekday/weekend pattern. Then we reclassified the urban regions based on the space clustering formed by the space factor matrix and core tensor. Finally, we further analysed the space–time interaction on different time scales to deduce the actual function and connection strength of each region. Our research shows that the application of individual-based spatial–temporal data in human mobility and space–time interaction study can help to analyse urban spatial structure and understand the actual regional function from a new perspective.  相似文献   

Exploring the interaction of surface roughness and slope gradient in controlling rates of soil loss from sloping farmland on the Loess Plateau of China     

Taotao Li  Longshan Zhao  Hongteng Duan  Yifan Yang  Yu Wang  Faqi Wu 《水文研究》2020,34(2):339-354

Surface roughness and slope gradient are two important factors influencing soil erosion. The objective of this study was to investigate the interaction of surface roughness and slope gradient in controlling soil loss from sloping farmland due to water erosion on the Loess Plateau, China. Following the surface features of sloping farmland in the plateau region, we manually prepared rough surfaces using four tillage practices (contour drilling, artificial digging, manual hoeing, and contour plowing), with a smooth surface as the control measure. Five slope gradients (3°, 5°, 10°, 15°, and 20°) and two rainfall intensities (60 and 90 mm/hr) were considered in the artificial rainfall simulation experiment. The results showed that the runoff volume and sediment yield increased with increasing slope gradient under the same tillage treatment. At gentle slope gradients (e.g., 3° and 5°), the increase in surface roughness prevented the runoff and sediment production, that is, the surface roughness reduced the positive effect of slope gradient on the runoff volume and sediment yield to a certain extent. At steep slope gradients, however, the enhancing effect of slope gradient on soil erosion gradually increased and surpassed the reduction effect of surface roughness. This study reveals the existence of a critical slope gradient that influences the interaction of surface roughness and slope gradient in controlling soil erosion on sloping farmland. If the slope gradient is equal to or less than the critical value, an increase in surface roughness would decrease soil erosion. Otherwise, the increase in surface roughness would be ineffective for preventing soil erosion. The critical slope gradient would be smaller under higher rainfall intensity. These findings are helpful for us to understand the process of soil erosion and relevant for supporting soil and water conservation in the Loess Plateau region of China.  相似文献   

Quantitative estimation of submarine groundwater discharge using airborne thermal infrared data acquired at two different tidal heights     

Ki‐mook Kang  Duk‐jin Kim  Yunjee Kim  Eunhee Lee  Bong‐Gwan Kim  Seung Hee Kim  Kyoochul Ha  Dong‐Chan Koh  Yang‐Ki Cho  Guebuem Kim 《水文研究》2019,33(7):1089-1100

Submarine groundwater discharge (SGD) plays an important role in coastal biogeochemical processes and hydrological cycles, particularly off volcanic islands in oligotrophic oceans. However, the spatial and temporal variations of SGD are still poorly understood owing to difficulty in taking rapid SGD measurements over a large scale. In this study, we used four airborne thermal infrared surveys (twice each during high and low tides) to quantify the spatiotemporal variations of SGD over the entire coast of Jeju Island, Korea. On the basis of an analytical model, we found a linear positive correlation between the thermal anomaly and squares of the groundwater discharge velocity and a negative exponential correlation between the anomaly and water depth (including tide height and bathymetry). We then derived a new equation for quantitatively estimating the SGD flow rates from thermal anomalies acquired at two different tide heights. The proposed method was validated with the measured SGD flow rates using a current meter at Gongcheonpo Beach. We believe that the method can be effectively applied for rapid estimation of SGD over coastal areas, where fresh groundwater discharge is significant, using airborne thermal infrared surveys.  相似文献   

Hydrological impact of a reservoir network in the upper Gan River Basin,China     

Ningpeng Dong  Zhongbo Yu  Chuanguo Yang  Mingxiang Yang  Wenzhuo Wang 《水文研究》2019,33(12):1709-1723

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