Multi-Model Approach for Assessing the Influence of Calibration Criteria on the Water Balance in Ouémé Basin

Hydrological models are very useful tools for evaluating water resources, and the hydroclimatic hazards associated with the water cycle. However, their calibration and validation require the use of performance criteria which choice is not straightforward. This paper aims to evaluate the influence of the performance criteria on water balance components and water extremes using two global rainfall-runoff models (HBV and GR4J) over the Ouémé watershed at the Bonou and Savè outlets. Three (3) Efficacy criteria (Nash, coefficient of determination, and KGE) were considered for calibration and validation. The results show that the Nash criterion provides a good assessment of the simulation of the different parts of the hydrograph. KGE is better for simulating peak flows and water balance elements than other efficiency criteria. This study could serve as a basis for the choice of performance criteria in hydrological modelling.

Hydrological Modelling of the Casamance River in Its Upstream Section (Basin at Kolda Level) to Predict Its Future States as a Function of Different Stresses

Flow records for stations in the Casamance basin are incomplete. Several gaps were noted over the 1980-2021 study period, making this study tedious. The aim of this study is to assess the potential impact of climate change on the flow of the Casamance watershed at Kolda. To this end, hydrological series are simulated and then extended using the GR2M rainfall-runoff model, with a monthly time step. Projected climate data are derived from a multi-model ensemble under scenarios SSP2-4.5 (scenario with additional radiative forcing of 4.5 W/m2 by 2099) and SSP5-8.5 (scenario with additional radiative forcing of 8.5 W/m2 by 2099). An analysis of the homogeneity of the rainfall data series from the Kolda station was carried out using KhronoStat software. The Casamance watershed was then delimited using ArcGIS to determine the morphometric parameters of the basin, which will be decisive for the rest of the work. Next, monthly evapotranspiration was calculated using the formula proposed by Oudin et al. This, together with rainfall and runoff, forms the input data for the model. The GR2M model was then calibrated and cross-validated using various simulations to assess its performance and robustness in the Casamance watershed. The version of the model with the calibrated parameters will make it possible to extend Casamance river flows to 2099. This simulation of future flows with GR2M shows a decrease in the flow of the Casamance at Kolda with the two scenarios SSP2-4.5 and SSP5-8.5 during the rainy period, and almost zero flows during the dry season from the period 2040-2059.

FUNCTIONAL ANALYSIS METHOD FOR THE M/G/1 QUEUEING MODEL WITH OPTIONAL SECOND SERVICE

By studying the spectral properties of the underlying operator corresponding to the M/G/1 queueing model with optional second service we obtain that the time-dependent solution of the model strongly converges to its steady-state solution. We also show that the time-dependent queueing size at the departure point converges to the corresponding steady-state queueing size at the departure point.

水平受荷桩“p-y+M-θ”分析方法

中国近海海上风电机组开发建设中,大直径单桩基础形式使用占比超70%。现行p-y曲线设计方法主要适用于小直径柔性桩,对大直径单桩侧向及桩底受荷描述能力不足,导致其严重低估刚柔性桩和刚性桩(分别常用于中国和欧洲的近海风电工程)的变形和承载能力,过于保守的设计给海上风电降本带来挑战。为此建立了能以统一的方式预测柔性、刚柔性和刚性单桩水平单调受荷响应的“p-y+M-θ”模型,并将该模型推广到循环荷载下单桩的响应分析。通过与相关试验结果比对发现,“p-y+M-θ”模型能较为准确地预测桩基水平加载响应。力图为水平受荷单桩工程设计提供简洁而可行的响应分析方法。

基于M-DeepLab网络的速度建模技术研究

本文提出了一种适用于速度建模方法的M-DeepLab网络框架,该网络将地震炮集记录作为输入,网络主体使用轻量级MobileNet,以此提升网络训练速度;并在编码环节ASPP模块后添加了Attention模块,且在解码环节将不同网络深度的速度特征进行了融合,既获得了更多的速度特征,又保留了网络浅部的速度信息,防止出现网络退化和过拟合问题。模型测试证明,M-DeepLab网络能够实现智能、精确的速度建模,简单模型、复杂模型以及含有噪声数据复杂模型的智能速度建模,均取得了良好的效果。相较DeepLabV3+网络,本文方法对于速度模型界面处的预测,特别是速度突变区域的预测,具有更高的预测精度,从而验证了该方法精确性、高效性、实用性和抗噪性。

Performance analysis of blockchain for civil aviation business data based on M/G/1 queuing theory

An Ethereum blockchain based on proof of stake ( PoS) consensus mechanism is used to achieve the data sharing within the civil aviation service platform for both airport group management and passengers. Considering the Gas consumption of Ethereum, the dynamic batch-service capacity constraint by the Block Gas Limit and the priority mechanism depending on the different Gas Price of transactions, M/ G/1 queuing theory with batch-service is used to construct the service model of transactions confirmation process in the proposed blockchain system, where the effects of transactions arrival rate, block capacity, service rate and number of nodes on the average confirmation time of transactions with different priority are analyzed, and eventually a performance analysis model of blockchain for civil aviation business data is proposed. The simulation results prove the usability and accuracy of the model, which can provide both theoretical basis for data sharing of civil aviation using Ethereum blockchain and the further optimization of transactions confirmation time.

基于Model/View/Controller的电子商务研究

分析了传统电子商务系统的缺陷 ,电子商务发展趋势 ,分析了M/V/C(Model/View/Controller)技术 ,提出了基于M/V/C电子商务并且分析了其体系结构及框架结构 ,以及在此框架之上构建电子商务的方法。

Simulation of pre-precipitation in Ni_(75)Al_(14)Mo_(11) alloy by microscopic phase-field model

The early precipitation process of Ni（75）Al（14）Mo（11） alloy was simulated by microscopic phase-field model at different temperatures.The microstructure of the alloy,the precipitation time of Llo structure and occupation probability of the three kinds of atoms were investigated.It is indicated that the non-stoichiometric Ll0（Ⅰ/Ⅱ） phases are found in the precipitation process.With the temperature increasing,the appearance time of Ll0 is brought forward.The Ll0（Ⅱ） structure always precipitates earlier than the Ll0（Ⅰ） structure.Compared with lower temperature,higher temperature brings the formation time of Ll0 phase forward and makes Ll0 phase have a higher order degree.But lower temperature shortens the process time of the Ll0 phase to the Ll2 phase.Al and Mo atoms tend to occupy γ site,Ni atom tends to occupy a and β sites.At the same temperature,Al atom has stronger occupation ability than Mo atom in the same site.Ni,Al and Mo collectively form the composited Ll2 structure.

口译过程认知心理模型“M”Model阐释

文章以释意理论与口译过程的两阶段解读为基础,以一般言语理解与言语产出为参考,分析口译过程的源语理解与译语表达,阐释口译过程认知心理模型"M"Model,即"口译过程=口译理解(语音知觉、词语识别、句法加工、语义表征与语篇理解)+口译表达(信息概念形成、思想言语转换、言语形式生成、言语产出监控)"。

ECMWF模式对我国西南环横断山区冬季近地面2m温度的预报评估

从冬季平均温度、温度日变化及日较差等方面入手,基于2021年CLDAS逐小时产品评估了ECMWF全球高分辨率确定性数值预报产品对我国西南环横断山区复杂地形区近地面2 m温度的预报能力,并通过区分高地形区(川西高原)和低地形区(四川盆地南部),对比了不同地形区近地面2 m温度预报的偏差特征。结果表明:(1)ECMWF模式可合理预报我国西南环横断山区冬季平均2 m温度的空间分布特征,但偏差分布与地形高度有关,随着地形高度的增加,预报偏差呈增大趋势。(2)ECMWF模式很好再现了西南环横断山区冬季温度的日变化特征,峰值时刻出现在14:00(北京时);各时刻温度的预报偏差在不同地形高度存在差异,川西高原和横断山区的最大负偏差出现在下午,四川盆地南部的最大负偏差出现在早晨。同时,高地形区各时刻的预报偏差均高于低地形区。(3)ECMWF模式对日内各时刻不同地形处2 m温度的空间分布均有合理预报,但偏差存在日变化特征。特别是在横断山区高地形区,其在各时刻有不同的冷暖偏差特征。(4)在环横断山区温度日较差预报偏差较大的区域(大致为昆明准静止锋线发生频次较高的区域),模式对于温度日较差较大的日数,其2 m温度的预报偏差要大于日较差较小的日数,且在该区域内,温度日较差的预报偏差相对不稳定。

基于药效团模型筛选CTX-M-14型超广谱β-内酰胺酶抑制剂

【目的】开发针对头孢噻肟-水解酶-14(CTX-M-14)型超广谱β-内酰胺酶(extended-spectrumβ-lactamase,ESBLs)的抑制剂,用以缓解细菌耐药带来的严重危害。【方法】使用DiscoveryStudio Visualizer(DS Visualizer)构建基于受体结构的药效团模型(structure-based pharmacophore,SBP)和基于配体共同特征的定性药效团模型(common feature pharmacophore generation,HIPHOP),并将验证后的模型作为查询条件对ZINC数据库进行以CTX-M-14蛋白为靶标的虚拟筛选,得到拟合分数良好的中药单体成分甘草酸(glycyrrhizic acid,GL),对其进行相关作用力分析、分子动力学模拟和结合自由能计算,分析甘草酸与CTX-M-14蛋白的结合模式、结合能力及稳定性;最后通过联合抑菌试验及酶动力学试验考察甘草酸的抗菌增敏活性、抑酶作用及抑酶方式。【结果】中药单体成分甘草酸主要与CTX-M-14蛋白活性中心多个氨基酸残基形成氢键和范德华作用力,两者的对接分数与结合自由能分别为-10 kcal/mol及-22.06 kcal/mol;甘草酸与头孢噻肟钠联用呈协同作用(FICI≤0.5);甘草酸可竞争性抑制β-内酰胺酶对底物抗生素的水解作用,对头孢噻肟钠的抑酶保护率可达58.53%,与克拉维酸接近(60.98%)。【结论】中药单体甘草酸可与CTX-M-14蛋白稳定结合,通过竞争性抑制β-内酰胺酶对底物抗生素的水解作用,提高多重耐药大肠杆菌E320和重组蛋白阳性菌BL-21对头孢噻肟钠的敏感性,实现抗生素的减量增效。

维数发散乘积回归模型的M估计

针对乘积回归模型,本文提出了非凹惩罚最小乘积相对误差的M估计(简称为惩罚MLPRE),该方法可有效处理高维样本量及参数维数随样本量增大而增大的稀疏乘积回归模型.基于一些正则条件,本文得到惩罚M-LPRE参数估计的相合性和渐近正态性等理论性质,通过数值模拟和实例分析,验证了惩罚M-LPRE准则的有效性.

基于M-K模型计算FLC无条件收敛新算法

M-K失稳模型的无条件收敛与快速求解对成形极限曲线(forming limit curve, FLC)的获取具有重要的理论意义与研究价值,也是理论FLC计算的难点之一.然而,在M-K失稳模型框架内基于复杂屈服准则计算成形极限曲线时,采用传统牛顿迭代算法无法保证收敛,而固定增量法则计算耗时过长,严重制约了M-K失稳模型的应用场景.因此,文章以锆合金为实验材料,提出了一种自适应增量算法,该算法通过迭代误差信息与震荡情况自适应调整迭代步长,不仅能够保证计算精度,满足无条件收敛,还能大幅提升计算速度.此外,本研究还验证了采用自适应增量法计算锆合金FLC的准确性,并分析了算法的迭代误差Err与初始应变增量对FLC预测结果的影响.结果表明:自适应增量法具有无条件保证收敛、计算速度快以及计算结果不受初始迭代步长影响的优势,其计算耗时仅为固定增量法的0.44%;此外,本研究认为初始参数中迭代误差小于10-6、初始应变增量小于0.001是得到稳定的FLC结果的前提条件;根据对锆合金FLC预测结果可知,在M-K模型框架内基于Yld2000-2d屈服准则理论采用自适应增量法计算可以很好地描述锆合金的塑性行为.由于自适应增量迭代法简单易用且计算高效,有望应用于有限元软件中子程序的开发,加速其计算速度并提高锆合金数值模拟精度.

服务失效状态为吸收状态及重试率为常数的M^([X])/M/1排队模型的主算子的谱分析

研究服务失效状态为吸收状态及重试率为常数的M^([X])/M/1排队模型的主算子在左半复平面中的谱.当顾客的到达率λ,服务员的服务率ν,顾客的重试率α和服务员的服务完成率b满足一定的条件时,证明了实部为-(λ+ν+b)的所有复数都不是该模型主算子的特征值;当λ,ν, α, b满足一定的条件时,证明了区间(-(λ+ν+b),0)中无穷多个点是该主算子的几何重数为1的特征值.

7.63 m焦炉装煤模型及装煤冒烟问题的探讨

建立了装煤模型,并根据模型对7.63 m焦炉增加装煤量后装煤冒烟的问题进行了分析,提出了在不减少装煤量、不增加操作时间的前提下,通过调整平煤时机、改进平煤操作达到消除装煤冒烟目的的方法。

口译过程认知心理模型“M”Model构建

以一般言语理解与产出研究为参照,本文分析口译中的源语理解与译语表达,聚焦于口译认知心理过程。以释意派理论与口译过程的两阶段解读为基础,利用心理语言学与认知心理学的相关理论,构建口译过程认知心理模型"M"Model,即口译过程=口译理解(语音知觉、词语识别、句法加工、语义表征与语篇理解)+口译表达(信息概念形成、思想言语转换、言语形式生成、言语产出监控)。

M⁃B模型弹塑性临界点确定方法

弹塑性临界点的确定对粗糙表面接触问题的研究至关重要。为了解决现有的M⁃B模型弹塑性临界点确定方法中,表征值不可测且难以应用的缺点,基于分形理论基本模型,运用数理统计得出了微凸体截断面积分布函数及概率分布密度。结合赫兹接触的理想弹、塑性接触模型得出了具有分形特征的平面⁃平面接触过程中的法向力模型。基于塑性变形时的实际接触面积与截断面积的区别,提出了修正因子,最后得出以临界法向力为表征量的弹塑性临界点确定方法。新方法以法向力为表征量且需通过校准试验得出,更具操作性与可信度。

EC细网格10 m风场产品在青岛港区的预报检验和随机森林订正

利用2021年3月—2022年2月EC细网格10 m风场预报产品,对其在青岛港区的风场预报能力进行检验和订正。结果表明:对于大港码头、董家口港自动站和董家口港浮标站,EC细网格前48 h的10 m风速预报偏差离散程度相对较小,预报偏差中位数均大于0,表明模式风速预报较实况有系统性偏强的特征。EC细网格24 h预报的10 m风速与实况风速相关性较好,3个站点的相关系数分别为0.76、0.73、0.82。EC细网格对大港码头各风向的风速预报均偏大,在实况风向为东北风和偏东风时,EC细网格风速预报的均方根误差和平均误差最大;对于董家口港自动站和董家口港浮标站,不同风向下EC细网格的风速预报均方根误差差别不大。EC细网格对3个站点的风向预报偏差主要集中在-45°~45°,实况风速越小,风向的预报偏差离散程度越大。利用随机森林算法对青岛港区EC细网格预报风速进行订正,预报精度均得到提高。

基于L-M算法的铝合金铸造过程界面换热系数的反问题模型

铝合金铸造过程铸件-铸模之间的界面换热系数的变化非常复杂,且预测非常困难。本文基于L-M(Levenberg-Marquardt)算法建立了铝合金铸造过程传热反问题模型,通过反问题分析获得铝合金铸造过程中铸件-铸模界面换热系数。通过将铸件-铸模界面换热系数反演值与标准值进行比较,验证传热反问题模型的准确性。在此基础上,分析了铸模上测点位置(与铸件-铸模界面距离、相邻测点间距)和温度测量误差对铸件-铸模界面换热系数反演值的影响规律,并给出了最优的测点布置方案和温度测量误差要求。通过铝合金铸造实验,用该反问题模型能求解出铝合金凝固过程中的铸件-铸模界面换热系数。