一种全数字QPSK解调器的Matlab仿真及设计

QPSK作为一种抑制载波的抗干扰能力较强的四相移键控调制方式,被广泛应用于无线卫星通信中.同步（载波同步和符号同步）是解调过程中最核心的问题之一.采用基于软件无线电的思想,把尽可能多的通信功能用可升级、可替换的软件来实现.载波同步采用数字Costas环的方式,符号同步采用模平方谱线估计法来完成,并通过Matlab仿真验证结果的可行性.将仿真获得的参数结合硬件平台,最终在工程上实现了一款基于FPGA（现场可编程逻辑门阵列）的气象卫星解调器的设计.     

基于MIKE 11的北京市典型区域降雨径流特征研究

以北京城市化发展区凉水河大红门闸控制流域为典型区域,在分析区域20世纪80年代到2000年后下垫面变化特征的基础上,结合区域同时期的降水和径流资料,采用MIKE11软件中的UR-BAN模块构建流域降雨径流模型,以流域模拟流量和实测流量拟合效果最佳为原则,利于多场次的实测降水进行降雨径流的模拟分析,研究区域城市化发展对水文特性变化的影响。     

闸底井注浆封堵处理实践

闸基下安装监测设备时需施工设备井,在施工及使用过程中因井封堵不严出现喷水冒砂现象。结合宿鸭湖水库工程,介绍了闸底井注浆封堵的方案设计和施工工艺,对侧向挤压注浆的注浆压力、水灰比及注浆措施进行了阐述,并对注浆原理及注浆效果进行了分析。     

基于雷达组合反射率拼图和深度学习的中尺度对流系统识别、追踪与分类方法

中尺度对流系统（Mesoscale Convective System,MCS）是很多对流性天气的主要致灾体,可导致严重的气象和水文灾害,如雷暴大风、冰雹、龙卷风和山洪。对MCS进行准确的识别和追踪,并根据追踪轨迹及获得的MCS特征实现MCS的分类,对灾害天气的分析和预报有重要意义。基于京津冀地区2010—2019年的雷达组合反射率拼图资料,分别使用支持向量机（SVM）、随机森林（RF）、极度梯度提升决策树（XGBoost）和深度神经网络（DNN）4种机器学习方法,研发了京津冀地区MCS的自动识别算法。使用时、空重叠追踪法对识别的MCS进行追踪匹配,得到包含强度、时间和空间信息的MCS追踪数据资料。在区分线状对流系统和非线状对流系统的基础上,进一步从经典的尾随层云（Trailing Stratiform,TS）、前导层云（Leading Stratiform,LS）和平行层云（Parallel Stratiform,PS）三类准线性MCS的概念模型和结构特征出发,根据追踪轨迹计算MCS的运动方向和MCS近似长轴两侧层状云和强对流云的面积占比,建立准线性MCS的分类算法。MCS的识别属于二分分类问题,以命中率（POD）、虚警率（FAR）、临界成功指数（CSI）和准确率（ACC）为评价指标,综合对比各项指标发现DNN模型较SVM、RF和XGBoost模型对MCS的识别效果更好。使用时、空重叠追踪法对DNN模型识别的MCS进行追踪,结合对两个追踪实例的分析,发现本研究所用的算法取得了很好的追踪结果,也进一步说明了深度学习方法识别MCS的准确性和优势。根据追踪轨迹计算某时刻MCS的运动方向,结合识别的层状云和强对流云的分布位置,准确实现了TS、LS和PS型准线性MCS的分类,为准线性MCS的生命史预测及其致灾天气特别是短时强降水的强度、位置和持续时间的客观预报提供了一种技术思路。      

江苏淤泥质海岸入海河道闸下淤积研究

通过建立ARIMA模型,分析了江苏淤泥质海岸四条入海河道(射阳河、新洋港、斗龙港和黄沙港)建闸后闸下河道的冲淤演变过程,预测闸下河道淤积量的变化情况。结果表明,射阳河闸下淤积量将会持续增加,到2010年预计量可达2.47×107m3,淤积量为四条河中最大;黄沙港和斗龙港有波动上升的趋势,但无射阳河明显,淤积量有小幅度增加;新洋港变化不大,已达到冲淤平衡的状态。     

基于FPGA的数字匹配滤波器的实现

对数字匹配滤波器的原理和结构进行了简要的介绍,重点给出了在现场可编程门阵列(FPGA)中数字匹配滤波器倒置结构的硬件实现.通过对设计电路的实时仿真表明:该数字匹配滤波器具有捕获精度高、速度快的特点,可应用于其它扩频系统的数字接收机中.     

定天镜的伺服驱动原理

主要介绍恒星光干涉仪实验系统的定天镜伺服驱动原理．采用电细分和逐级升、降速的方法来减小定天镜在转动时的振动，提高定位、跟踪精度．由于应用了４００的电细分和１０００倍的传速比，步进电机的步距角达到０．００６４８°．     

Flap gate farm: From Venice lagoon defense to resonating wave energy production. Part 2: Synchronous response to incident waves in open sea

We consider a flap gate farm, i.e. a series of P arrays, each made of Q neighbouring flap gates, in an open sea of constant depth, forced by monochromatic incident waves. The effect of the gate thickness on the dynamics of the system is taken into account. By means of Green's theorem a system of hypersingular integral equations for the velocity potential in the fluid domain is solved in terms of Legendre polynomials. We show that synchronous excitation of the natural frequencies of Sammarco et al. (2013) yields large amplitude response of gate motion. This aspect is fundamental for the optimisation of the gate farm for energy production.     

简易门禁系统控制器系统设计

介绍了一个以AT89S52单片机为主要处理单元,配合存储电路、复位电路以及其它元器件实现门禁地址的分配及存储判定的门禁控制电路,该控制器通过对串口数据的处理,能实时对PC进行通信并通过实时代码验证各项控制器操作.     

Fifteen-stage operation of gated spillways for flood routing management through artificial reservoirs

Abstract

A procedure to identify sets of operational rules for gated spillways for optimal flood routing management of artificial reservoirs is proposed. The flood retention storage of a dam having a gated flood spillway is divided into 15 sub-storages whose surface elevations are identified as critical levels. The most suitable operation set for the downstream conditions and for the dam can be chosen from many derived operation sets. The spillway gates are operated in an optimum way for any floods from very small magnitudes to the probable maximum flood (PMF), without having to forecast the actual magnitude of the incoming flood hydrograph. Decision floods are formed by dividing the PMF into 15 sub-hydrographs by 5 and 10% increments in the ranges 5–50% and 50–100% of the PMF, respectively. Many potential spillway gate openings from closed to fully open are chosen initially. As a result of a series of routing simulations of 15 decision floods, a set of 15 gate openings is determined such that all floods from very small magnitudes to the PMF may be routed without overtopping the dam crest. Next, a few more 15-stage operation rules are determined such that the gate openings of the initial stages are decreased as their critical levels are increased stepwise, with the objective of attenuating smaller floods more effectively and releasing higher outflows for larger floods close to and including the PMF. The developed model is applied to the Catalan and Aslantas dams in Turkey, both of which serve for flood mitigation as well as hydropower generation.

Citation Haktanir, T., Citakoglu, H., and Acanal, N., 2013. Fifteen-stage operation of gated spillways for flood routing management through artificial reservoirs. Hydrological Sciences Journal, 58 (5), 1013–1031.

Editor Z.W. Kundzewicz; Associate editor A. Montanari