VOCs源强不确定性对ROx平衡影响的模拟分析

本文对区域空气质量模式WRF-Chem主要化学模块进行了改进,定量输出大气关键自由基(ROx=OH+HO_(2)+RO_(2))参与反应的主要化学过程生成率、损耗率与相关收支平衡量,为无法定量分析和比较VOCs源强的不确定性对ROx平衡影响提供了一种新的定量分析方法,由此可减小污染防治中臭氧生成敏感区的误判,有助于完善开展快速城市群建设背景下大气环境效应的研究体系.人为VOCs排放源(AVOCs)增加(减少)68%后,三大城市群中OH、HO_(2)和RO_(2)生成率增幅达到4%—280%(对应减少为2%—80%),以北京、上海、广州为三大城市群代表的城市ROx初级生成率增幅达到35%—48%(对应减少为26%—39%).3个城市中,ROx生成率贡献最大的两类化学过程均为O1D+H2O和HCHO,ALD2等的光解,ROx损耗主要关联的化学过程为OH+NO_(2)(占比达71%—85%).分析表明,当AVOCs源增加68%之后,ROx白天月平均浓度在京津冀、长三角、珠三角的增幅OH为4%—48%、4%—52%与4%—44%,HO_(2)为10%—120%、10%—140%与10%—120%,RO_(2)为20%—280%、20%—240%与10%—140%,以大气边界层内ROx白天经向月均值增幅计算,OH为1%—5%,HO_(2)为4%—16%,RO_(2)为6%—26%.AVOCs源排放量增加68%后,导致ROx收支平衡发生变化,直接影响与NOx反应的ROx的损耗率(Ln)和ROx的生成率(Q)值,部分地区从VOCs敏感区转变为NOx敏感区,这意味着AVOCs排放源的低估导致VOCs敏感区的夸大,从而降低O3调控对策的有效性,从而也说明VOCs的不确定性导致的ROx的变化对局地污染防控策略制定影响重大.

一类强耦合强不确定性强非线性快时变系统复合控制

分析一类强耦合强不确定性强非线性快时变系统的控制问题。基于系统力学特性和动力学特性,提出一种复合控制方法。该复合控制方法由三个核心模块组成,依次为强耦合强不确定性控制模块、强非线性快时变控制模块、智能调度模块。以某典型强耦合强不确定性强非线性快时变特性飞行器对象为例,给出了采用该复合控制方法的详细设计。最后,在精确的仿真模型基础上,考虑天地不一致性情况,进行了多组仿真分析,仿真结果表明,该方法有效、可靠。

VOCs源强不确定性对臭氧生成及污染防治影响的模拟分析

本文基于三维区域空气质量模式WRF-Chem,通过修改模式化学模块,量化输出过程量和诊断量,提供了一种定量分析挥发性有机化合物(VOCs)源强不确定性对O_(3)生成影响的方法.为无法定量计算VOCs源强导致的臭氧生成率[P(O_(3))]偏差,以及由此对O_(3)体积分数分布和污染控制相关联的VOCs敏感区和NOx敏感区分布的误判提供了方法参考.采用标准统计参数对WRF-Chem模式的气象场与污染场模拟性能进行了评估,相关指标均优于前人结果.以INTEX-B(intercontinental chemical transport experiment-phase B)人为源、FINNv1(fire inventory from NCAR version 1)生物质燃烧源和MEGAN(model of emissions of gases and aerosols from nature)生物源作为基准源,并以卫星观测数据作为约束,对排放源进行改进,评估了源改进前后臭氧生成率[P(O_(3))]、O_(3)体积分数和O_(3)控制敏感区指标(Ln/Q)的变化情况.仅人为VOCs(AVOCs)源增加68%后,P(O_(3))模拟峰值增升比例达13%~82%,以北京观测站点为例,P(O_(3))模拟月均峰值增加42%(22.5×10^(-9) h^(-1)).对P(O_(3))形成贡献比例最大的主要化学反应是HO2+NO(占比约68%),AVOCs源增加68%后,该反应贡献比例下降至65%.在改进源下,P(O_(3))普遍增加达到2×10^(-9)~4×10^(-9) h^(-1),O_(3)各季节增幅较大的区域均主要集中在京津冀、长三角和珠三角中心城市及周边区域,与我国大型城市区基本都是VOCs敏感区的结论一致.整体而言,VOCs源强改进后,NOx敏感区O_(3)体积分数增加幅度不大,不超过4×10^(-9),而部分VOCs敏感区增幅超过20×10^(-9).VOCs源强的不确定性会影响O_(3)形成过程中NOx和VOCs敏感区的判断,特别是VOCs源强明显低估会夸大VOCs敏感区的范围,从而降低O_(3)调控对策的有效性.

从不确定性规避理论看中西跨文化交际的心态调整

从不确定性规避理论出发分析中西文化的不同特点,探讨了中西文化对待交际的心态,提出了中方交际者积极取效西方文化的合理因素并调整自己对待交际中的不确定性(因素)的心态是成功的中西跨文化交际的关键一环。

带有非线性不确定参数的线性时滞系统的鲁棒稳定性

研究一类带有非线性不确定参数的线性时滞系统的鲁棒稳定性问题,针对不确定矩阵满足非结构不确定性、强结构不确定性、矩阵多胞形结构不确定性等情形,利用Lyapunov方法、不等式技巧及线性矩阵不等式,获得该系统渐近稳定的一系列充分条件。

离散时滞不确定系统的鲁棒稳定性分析

针对强结构不确定性情形,利用线性系统基于特征值的稳定性特征,研究了具有时滞的不确定离散系统的鲁棒稳定性问题,给出并证明了判断时滞不确定离散系统鲁棒稳定的充分条件.

计及可靠性成本的风光储微电网储能容量协同优化

对比常规能源,新能源具备可再生、污染低、资源丰富的优势,其中风光发电被大规模引入到微电网系统,但由于其发电量具有较强的不确定性,这使得如何提高新能源消纳水平、提升电力系统运行稳定性以及降低微电网配置成本成为了充满挑战性的重要问题。针对上述问题,文章提出一种计及可靠性成本,同时考虑风、光资源多时间尺度不确定性的风光储互补微电网系统储能容量协同优化的方法。该方法采用自回归滑动平均模型和Homer软件仿真离散的风速、光辐照度序列,构建出风机、光伏发电机的出力模型;采取电量不足期望值为评估指标建立可靠性成本函数,构建出微电网配置成本模型;使用改进二阶振荡粒子群算法求解系统最优配置成本。算例结果表明了该方法的可行性及经济性,可为实际风光储互补微电网系统配置规划提供参考。

基于鲁棒近似方法的高超声速导弹复合控制方法研究

针对导弹在超高速飞行时产生的通道间强耦合、模型强不确定性,用反馈线性化与鲁棒近似复合控制方法进行控制器设计。用反馈线性化抑制通道间的耦合,用鲁棒近似方法抑制参数偏差。仿真验证了控制方法的有效性。

考虑电量执行进度公平性的月度电能交易计划四阶段建模

随着新能源占比的不断提升,新能源输出电量较强的不确定性给现有采用解耦串行方式的月度电能交易计划编制带来诸多问题。文中提出了一种月度电能交易计划编制的时序仿真法,其中:新能源与传统机组的耦合协同优化方式可充分考虑新能源电量不确定性的影响,保障计划准确实施;"分段建模,前细后粗"的四阶段建模思路,可充分利用问题特点,既保证计算收敛且提升计算速度又方便计入运行安全约束,为调度计划制定奠定良好基础;年时间尺度电量执行进度基尼系数约束的引入,可保证各个发电实体电量执行进度的均衡,从而更好地保证公平性。算例结果验证了所提方法的可行性与有效性。

基于轨迹线性化的高超声速飞行器非线性姿态控制

针对强非线性、强耦合、强不确定特性的高超声速飞行器姿态控制问题,提出了具有非线性前馈补偿与闭环反馈功能的高超声速飞行器轨迹线性化非线性姿态控制方法。首先,为方便控制器设计,给出了面向控制的高超声速飞行器姿态运动/动力学模型与问题描述。其次,阐述了轨迹线性化与基于小扰动线性化、切换变增益的控制方法相比在非线性控制方面的性能优势,并运用轨迹线性化控制思想和时标分离原则在姿态和角速率回路分别设计了虚拟控制量和控制力矩,实现了有限干扰下再入全程的非线性姿态跟踪控制。最后,仿真结果验证了所提方法能够确保再入过程高超声速飞行器姿态快速、稳定地跟踪预设指令。

Solvability Condition for Robust Stabilization Problem of Control Systems with Parameter Uncertainties

Aim The solvability condition for robust stabilization problem associated with a plant family P(s,δ) having parameter uncertainty δ was considered. Methods Using Youla parameterization of the stabilizers this problem was transformed into a strong stabilization problem associated with a related plant family G (s, δ). Results A necessary solvability condition was established in terms of the parity interlacing property of each element in G(s,δ). Another apparently necessary solvability condition is that every element in P(s,δ) must be stabilizable. Conclusion The two conditions will be compared with each other and it will be shown that every element in G(s,δ) possesses parity interlacing property if P(s,δ) is stabilizable.

地震危险性概率分析方法:存在的问题和纠正(英文)

地震危险性概率分析(PSHA)是目前最广泛应用于地震灾害与风险性评估的方法。然而它在计算中却存在着一个错误:把强地面运动衰减关系(一个函数)的条件超越概率等同于强地面运动误差(一个变量)的超越概率。这个错误导致了运用强地面运动误差(空间分布特征)去外推强地面运动的发生(时间分布特征)或称之为遍历性假设,同时也造成了对PSHA理解和应用上的困难。本文推导出新的灾害计算方法(称之为KY-PSHA)来纠正这种错误。

Effect of the Chord-Brace Angle on the Strength of Rectangular Hollow Sections K- and N-Joints in Galvanized Structures

An important consideration when using hot-dip galvanized tubular structures is the uncertainty of the joint behaviour due to the possible reduction in the global joint resistance produced by the vent holes required for the galvanizing process. This paper assesses the effect on the joint strength of the angle between the brace members and the chord in a K- or N-joints made with rectangular hollow sections. The study is focused on the case when those brace members include characteristic holes required for the hot-dip galvanizing process. To accomplish the objective of the proposed work, some tests on full-scale K- and N-joints, including angles of 35°, 45°, 55° and 90°, were carried out. The experimental work was complemented by a validated numerical simulation in order to give some design recommendations and to extend the research to other joint configurations.

Strong/weak limits and strong/weak differentials of multi-variable indeterminate forms. II: Supplementary annotations and analysis

Supplementary annotations on special forms 1to 4, discussion on the general characteristics of K(t) and K(t, t), and analyses on two noticeable limits are presented in this part. It is demonstrated that strong and weak parabolic transforms can be employed to change the standard form of a multi-variable indeterminate form into xmK type, hence to derive the standard formulae of the limit and the differential.

Improving the simulation of terrestrial water storage anomalies over China using a Bayesian model averaging ensemble approach

The ability to estimate terrestrial water storage(TWS)is essential for monitoring hydrological extremes(e.g.,droughts and floods)and predicting future changes in the hydrological cycle.However,inadequacies in model physics and parameters,as well as uncertainties in meteorological forcing data,commonly limit the ability of land surface models(LSMs)to accurately simulate TWS.In this study,the authors show how simulations of TWS anomalies(TWSAs)from multiple meteorological forcings and multiple LSMs can be combined in a Bayesian model averaging(BMA)ensemble approach to improve monitoring and predictions.Simulations using three forcing datasets and two LSMs were conducted over China's Mainland for the period 1979–2008.All the simulations showed good temporal correlations with satellite observations from the Gravity Recovery and Climate Experiment during 2004–08.The correlation coefficient ranged between 0.5 and 0.8 in the humid regions(e.g.,the Yangtze river basin,Huaihe basin,and Zhujiang basin),but was much lower in the arid regions(e.g.,the Heihe basin and Tarim river basin).The BMA ensemble approach performed better than all individual member simulations.It captured the spatial distribution and temporal variations of TWSAs over China's Mainland and the eight major river basins very well;plus,it showed the highest R value(>0.5)over most basins and the lowest root-mean-square error value(<40 mm)in all basins of China.The good performance of the BMA ensemble approach shows that it is a promising way to reproduce long-term,high-resolution spatial and temporal TWSA data.

A Study on the Prediction Method of Strong Earthquakes Based on Dynamic Seismicity Patterns with Dynamic Implications

Seismic gap method is one of the effective earthquake prediction methods using seismicity patterns. However, this method has some limitations and uncertainty when using it singly in predicting earthquakes. This paper puts forward the prediction method using the dynamic seismicity pattern with dynamic implications. This method considers the formation and evolution of the seismic gap on the basis of plate movement and structural characteristics. Through analysis of 26 cases of earthquakes of MS≥5.0 occurring in East China and South China, this paper obtains the relationship between the main shock with seismic gap and active fault's location, as well as the relationship between the seismic gap and location and strike of active faults. Meanwhile, this paper provides a dynamic explanation of the differences in the formation and evolution patterns of the seismic gap between the two regions, thus providing the physical basis for and reducing the uncertainty of predicting earthquakes using the seismic gap method.

双分式Brown运动的自相交局部时和相遇局部时

考虑一个双分式Brown运动的局部时、自相交局部时和两个独立的双分式Brown运动的相遇局部时问题.通过双分式Brown运动的强局部不确定性、L^2收敛和混沌展开,验证自相交局部时和相遇局部时的存在性和光滑性.

Effect of the uncertainty in soil-water characteristic curve on the estimated shear strength of unsaturated soil

Most failures or instabilities of geotechnical structures commonly result from shear failure in soil. In addition, many infrastructures are constructed within the unsaturated zone. Therefore, the determination of shear strength of unsaturated soil is crucial in geotechnical design. The soil-water characteristic curve(SWCC) is commonly used to estimate the shear strength of unsaturated soil because the direct measurement is time-consuming and costly. However, the uncertainty associated with the determined SWCC is rarely considered in the estimation of the shear strength. In this paper, the uncertainties of SWCC resulted from different factors are reviewed and discussed. The variability of the estimated shear strength for the unsaturated soil due to the uncertainty of SWCC associated with the best fit process is quantified by using the upper and lower bounds of the determined SWCC. On the other hand, the uncertainties of the estimated shear strength due to different initial void ratios or different confining pressures are quantified by adopting different SWCCs. As a result, it is recommended that the measured SWCC from the conventional Tempe cell or pressure plate needs to be corrected by considering different stress levels in the estimation of the shear strength of unsaturated soil.