Study on NOx Formation in CH4/Air Jet Combustion

With the development of reaction kinetics and transfer science, the modeling of NOx formation plays more and more important roles in the protection of environment and the design of combustion reactors; in this case,turbulence-chemistry model and NOx formation model are the two most important aspects. For thermal NOx mechanism, this article studied the CH4/air system and applied a set of latest NO formation rate constants published at the Leed University which replaced the original model code in FLUENT to increase its precision on prediction of NO concentration. The realizable k-ε model, Reynold Stress model and standard k-ε model were also investigated to predict the turbulent combustion reaction, which indicated that the simulation results of velocities, temperatures and concentrations of combustion productions by the standard k-ε model were in good accordance with the experimental data. With the application of the simulation results to the experimental data to fit some important kinetic parameters in the equation of O atom model and revision of the equation later, this article obtained a new NO formation rate model. It has been proved that the prediction of the developed model coincides well with the measurements.

Dynamic WTA optimization model of air defense operation of warships' formation

WTA （weapon-target allocation） of air defense operation is a very complicated problem and current models focus on static and restricted WTA problem mostly. Based on the dynamic characteristics of air defense operational command and decision of warships＇ formation, a dynamic WTA model is established. Simulation results show that switch fire and repetition fire of anti-air weapon system affect the result of the air defense operation remarkably and the dynamic model is more satisfying than static ones. Related results are gained based on the analysis of the simulation results and the results are accordant with the intuitionistic tactical judgment. The model is some reference for the research of air defense C^3I system of warships＇ formation.

Relationship between Formation Water Rate,Equivalent Penetration Rate and Volume Flow Rate of Air in Air Drilling

Formation water invasion is the most troublesome problem associated with air drilling. However, it is not economical to apply mist drilling when only a small amount of water flows into wellbore from formation during air drilling. Formation water could be circulated out of the wellbore through increasing the gas injection rate. In this paper, the Angel model was modified by introducing Nikurade friction factor for the flow in coarse open holes and translating formation water rate into equivalent penetration rate. Thus the distribution of annular pressure and the relationship between minimum air injection rate and formation water rate were obtained. Real data verification indicated that the modified model is more accurate than the Angel model and can provide useful information for air drilling.

Research on prediction model of formation temperature of ammonium bisulfate in air preheater of coal-fired power plant

Ammonium bisulfate(ABS)is a viscous compound produced by the escape NH_(3) in the NO reduction process and SO_(3) in the flue gas at a certain temperature,which can cause the ash corrosion of the air preheater in coal-fired power plants.Therefore,it is essential to study the formation temperature of ABS to prevent the deposition of ABS in air preheaters.In this paper,the SO_(3) reaction kinetic model is used to analyze the SO_(3) generation process from coal combustion to the selective catalytic reduction(SCR)exit stage,and the kinetic model of NO reduction is used to analyze the NH_(3) escape process.A prediction model for calculating the ABS formation temperature based on the S content in coal and NO reduction parameters of the SCR is proposed,solving the difficulty of measuring SO_(3) concentration and NH_(3) concentration in the previous calculation equation of ABS formation temperature.And the reliability of the model is verified by the actual data of the power plant.Then the influence of S content in coal,NH_(3)/NO_(x) molar ratio,different NO_(x) concentrations at SCR inlet,and NO removal efficiency on the formation temperature of ABS are analyzed.

Effect of microwave frequency on plasma formation in air breakdown at atmospheric pressure

Microwave breakdown at atmospheric pressure causes the formation of a discrete plasma structure. The onedimensional fluid model coupling Maxwell equations with plasma fluid equations is used to study the effect of the microwave frequency on the formation of air plasma. Simulation results show that, the filamentary plasma array propagating toward the microwave source is formed at different microwave frequencies. As the microwave frequency decreases, the ratio of the distance between two adjacent plasma filaments to the corresponding wavelength remains almost unchanged（on the order of 1/4）, while the plasma front propagates more slowly due to the increase in the formation time of the new plasma filament.

On the Formation of a Bead Structure of Spark Channels during a Discharge in Air at Atmospheric Pressure

The conditions for the formation of spark channels with a bead structure in an inhomogeneous electric field at different polarities of voltage pulses are studied.Voltage pulses with an amplitude of up to 150 kV and a rise time of≈1.5μs were applied across a 45-mm point-to-plane gap.Under these conditions,spark channels consisting of bright and dim regions(bead structure)were observed.It is shown that when current is limited,an increase in the rise time and the gap length does not affect the formation of the bead structure.It was found that an increase in the amplitude of voltage pulses leads to an increase in the length of beads.The appearance of the bead structure is more likely at negative polarity of the pointed electrode.The formation of spark channels was studied with a four-channel ICCD camera.

Immune multi-agent model using vaccine for cooperative air-defense system of systems for surface warship formation based on danger theory

Aiming at the problem on cooperative air-defense of surface warship formation, this paper maps the cooperative airdefense system of systems （SoS） for surface warship formation （CASoSSWF） to the biological immune system （BIS） according to the similarity of the defense mechanism and characteristics between the CASoSSWF and the BIS, and then designs the models of components and the architecture for a monitoring agent, a regulating agent, a killer agent, a pre-warning agent and a communicating agent by making use of the theories and methods of the artificial immune system, the multi-agent system （MAS）, the vaccine and the danger theory （DT）. Moreover a new immune multi-agent model using vaccine based on DT （IMMUVBDT） for the cooperative air-defense SoS is advanced. The immune response and immune mechanism of the CASoSSWF are analyzed. The model has a capability of memory, evolution, commendable dynamic environment adaptability and self-learning, and embodies adequately the cooperative air-defense mechanism for the CASoSSWF. Therefore it shows a novel idea for the CASoSSWF which can provide conception models for a surface warship formation operation simulation system.

Study on NO_x Formation in CH_4/Air Jet Combustion

With the development of reaction kinetics and transfer science, the modeling of NOx formation plays more and more important roles in the protection of environment and the design of combustion reactors; in this case, turbulence-chemistry model and NOx formation model are the two most important aspects. For thermal NOx mechanism, this article studied the CH4/air system and applied a set of latest NO formation rate constants published at the Leed University which replaced the original model code in FLUENT to increase its precision on prediction of NO concentration. The realizable k-ε model, Reynold Stress model and standard k-ε model were also investigated to predict the turbulent combustion reaction, which indicated that the simulation results of velocities, temperatures and concentrations of combustion productions by the standard k-ε model were in good accordance with the experi- mental data. With the application of the simulation results to the experimental data to fit some important kinetic pa- rameters in the equation of O atom model and revision of the equation later, this article obtained a new NO forma- tion rate model. It has been proved that the prediction of the developed model coincides well with the measure- ments.

WATER MASS FORMATION IN THE SOUTH INDIAN OCEAN BY AIR-SEA FLUXES

Indian Central Water （ICW） and Subantarctic Mode Water （SAMW） formation rates are estimated from two air-sea flux products, the Comprehensive Ocean-Atmosphere Data Set （COADS） and the Southampton Oceanography Centre （SOC） climatology. The ICW formation is estimated to be 8 Sv (1 Sv = 106m3·s-1 ) from both products, with more contributions from freshwater flux. From the COADS product, the SAMW formation rate is estimated to be 31 Sv in the potential density range of 26.5-26.9σθ, with also a significant contribution from freshwater flux. However, the SAMW formation rate estimated from the SOC product is much smaller, which may be due to bias of the SOC heat flux. Poorer quality of the flux products in the Southern Ocean may also contribute to the difference.

Optimal Formation Reconfiguration Control of Multiple UCAVs Using Improved Particle Swarm Optimization

Optimal formation reconfiguration control of multiple Uninhabited Combat Air Vehicles （UCAVs） is a complicated global optimum problem. Particle Swarm Optimization （PSO） is a population based stochastic optimization technique inspired by social behaviour of bird flocking or fish schooling. PSO can achieve better results in a faster, cheaper way compared with other bio-inspired computational methods, and there are few parameters to adjust in PSO. In this paper, we propose an improved PSO model for solving the optimal formation reconfiguration control problem for multiple UCAVs. Firstly, the Control Parameterization and Time Diseretization （CPTD） method is designed in detail. Then, the mutation strategy and a special mutation-escape operator are adopted in the improved PSO model to make particles explore the search space more efficiently. The proposed strategy can produce a large speed value dynamically according to the variation of the speed, which makes the algorithm explore the local and global minima thoroughly at the same time. Series experimental results demonstrate the feasibility and effectiveness of the proposed method in solving the optimal formation reconfiguration control problem for multiple UCAVs.

Experimental and modeling study of de novo formation of PCDD/PCDF on MSW fly ash

The effect of sulfur dioxide （SO2） on the formation of polychlorinated dibenzo-p-dioxins （PCDDs） and polychlorinated dibenzofurans （PCDFs） has been studied in an entrained-flow reactor （EFR） under simulated waste combustion conditions. A chlorination model based on conditional probability was employed to evaluate the homologue patterns of PCDDs and PCDFs. Results revealed that the presence of SO2 did not alter the formation pathway although SO2 suppressed PCDD/F formation. The prediction model of PCDF showed good agreement with the experimental data （R--0.95）, whereas the prediction for PCDDs did not correlate well with the experimental data. This may be explained because potential chlorination pathways play a significant role in PCDF formation, whereas PCDDs are mainly formed through condensation reactions. Furthermore, the result indicated that the steric hindrance during formation has more effects on PCDD than on PCDF due to the symmetric molecular structures of PCDDs.

Tracking Source Variations of Inhalation Cancer Risks and Ozone Formation Potential in Hong Kong over Two Decades(2000−2020)Using Toxic Air Pollutant Monitoring Data

Toxic air pollutants(TAPs)are a class of airborne chemicals known or suspected to cause serious health issues.This study,applying positive matrix factorization and inhalation unit risk estimates of TAPs,quantifies the changes in significant sources contributing to inhalation cancer risks(ICRs)from 2000 to 2020 in Hong Kong,China.Total ICR decreased from 1701 to 451 cases per million between 2000−2004 and 2016−2020,largely attributed to the reduction in diesel particulate matter(DPM),gasoline and solvent use-related volatile organic compounds(VOCs),and coal/biomass combustion-related polycyclic aromatic hydrocarbons and metal(loid)s.The regional contribution of VOCs associated with industrial and halogenated solvent sources increased substantially,representing the largest non-DPM ICR contributor(37%)in 2016−2020,stressing the need for a more comprehensive risk evaluation across the fast-growing and densely populated Greater Bay Area(GBA).ICRs in Hong Kong and the GBA will likely remain over 100 cases per million by 2050.The contributions to ozone formation potential of VOC/carbonyl sources were quantified,which show a notable shift from being solvent/gasoline-dominant in 2000−2004 to being more evenly shared by various sources in 2016−2020.Establishing a similar TAP monitoring network in the GBA is anticipated to provide the monitoring data needed to facilitate the development of more informed air quality management strategies.

Cooperative decision-making algorithm with efficient convergence for UCAV formation in beyond-visual-range air combat based on multi-agent reinforcement learning

Highly intelligent Unmanned Combat Aerial Vehicle(UCAV)formation is expected to bring out strengths in Beyond-Visual-Range(BVR)air combat.Although Multi-Agent Reinforcement Learning(MARL)shows outstanding performance in cooperative decision-making,it is challenging for existing MARL algorithms to quickly converge to an optimal strategy for UCAV formation in BVR air combat where confrontation is complicated and reward is extremely sparse and delayed.Aiming to solve this problem,this paper proposes an Advantage Highlight Multi-Agent Proximal Policy Optimization(AHMAPPO)algorithm.First,at every step,the AHMAPPO records the degree to which the best formation exceeds the average of formations in parallel environments and carries out additional advantage sampling according to it.Then,the sampling result is introduced into the updating process of the actor network to improve its optimization efficiency.Finally,the simulation results reveal that compared with some state-of-the-art MARL algorithms,the AHMAPPO can obtain a more excellent strategy utilizing fewer sample episodes in the UCAV formation BVR air combat simulation environment built in this paper,which can reflect the critical features of BVR air combat.The AHMAPPO can significantly increase the convergence efficiency of the strategy for UCAV formation in BVR air combat,with a maximum increase of 81.5%relative to other algorithms.

黄河三角洲地区大气复合污染特征、成因与VOCs来源解析

为了解黄河三角洲区域细颗粒物(PM_(2.5))和臭氧(O_(3))大气复合污染特征和成因,本文利用2021年和2022年夏秋季黄河三角洲中心城市东营市、滨州市的挥发性有机物(VOCs)连续观测数据及常规污染物数据,识别对O_(3)和二次有机气溶胶(SOA)生成有显著贡献的VOCs物种并对VOCs进行来源解析,同时利用基于观测的化学盒子模型探讨O_(3)的生成敏感性.结果表明:①黄河三角洲地区PM_(2.5)和O_(3)浓度“双高”的大气复合污染主要出现在秋季,夏季东营市和滨州市首要污染物均为O_(3),距离入海口越远的站点O_(3)超标天占比越高;秋季东营市和滨州市首要污染物均为PM_(2.5),且超标情况相近.②烯烃和含氧挥发性有机物(OVOCs)对臭氧生成潜势(OFP)的贡献大,优势物种为乙醛;芳香烃对SOA生成潜势(SOAFP)的贡献大,优势物种为1,2,3-三甲苯.③东营市夏秋季O_(3)生成均处于VOCs和NO_(x)协同控制区,且夏季O_(3)对NO_(x)更为敏感;滨州市夏秋季O_(3)生成分别处于VOCs和NO_(x)协同控制区、VOCs控制区,且夏季O_(3)对NO_(x)敏感性更高,秋季对VOCs敏感.④油气挥发源、工业排放源和机动车尾气排放源为该区域VOCs的主要来源,且VOCs来源解析结果存在空间上和季节上的差异.夏季,区域溶剂源和生物源VOCs的贡献率增加,东营市溶剂源贡献率(28.2%)明显高于滨州市(6%),机动车尾气排放源贡献率(11.5%)低于滨州市(29.6%);秋季,区域燃烧源和生物质燃烧源贡献率增加,东营市(25.9%)油气挥发源贡献率明显低于滨州市(42.4%).研究显示,黄河三角洲地区夏季应实施VOCs和NO_(x)的协同减排,秋季应优先控制VOCs排放;其次需要加强对油气挥发源、工业排放源和机动车尾气源VOCs的管控.

基于改进差分进化算法的跨平台武器目标分配方法

现代战争中,跨平台武器单元的协同利用,是合同编队体系的重要内容,作战方式也正由平台级协同向着能力要素级协同转变,这对武器目标分配问题的解决提出了更大挑战。本文将武器单元的最小划分单位细化到能力要素级,以毁伤概率与成本消耗为优化目标,面向多种来袭目标的编队防空场景,提出了跨平台武器目标分配算法。同时,基于混沌映射提出了混沌种群重构(chaotic population reconstruction,CPR)机制,并结合带存档的自适应差分进化(adaptive differential evolution with optional external archive,JADE)算法提出了CPR-JADE算法,利用CPR机制可以帮助算法在解决高维复杂约束问题时跳出局部最优。再将其运用到武器目标分配模型上,实现了对模型的高效求解。最后,通过在多种数据规模下与其他进化优化算法的仿真对比试验分析,验证了所提方法的正确性与有效性。

基于层级结构的空−地协同预设时间最优容错控制

研究了发生执行器故障的无人机−无人车异构编队系统的层级预设时间最优编队控制问题.以保容错性能和收敛速度的优化控制为研究主线,以层级控制、图博弈理论和预设时间控制为技术基础,构建了一种预设时间最优容错控制算法.虚拟层设计了基于一致性跟踪误差和能量消耗的二次型性能指标函数,借助耦合哈密顿−雅克比−贝尔曼(Hanmilton-Jacobi-Bellman,HJB)方程和强化学习求解近似最优控制策略,实现多智能体的同步最优控制和交互纳什均衡.实际控制层基于最优信号并利用滑模控制和自适应技术,设计了预设时间容错跟踪控制器,实现对最优编队轨迹的有限时间跟踪.在保证全局收敛时间完全不依赖于系统的初始状态和控制器参数的同时,也有效实现对执行器故障参数的逼近.最后,通过仿真实验验证了所提控制策略的有效性.

面向自杀式无人机饱和攻击的海空跨域无人协同反制策略

针对海洋环境下反制自杀式无人机饱和攻击问题,文中研究了目标数量远超我方情况下的海空跨域无人平台协同反制策略,提出一种结合改进的遗传算法与联盟形成博弈的协同算法。首先根据海空跨域无人平台攻击特性与运动特性,结合最大最小策略设计代价函数;然后结合任务需求对遗传算法进行改进,对交叉和变异过程进行引导和限制,在提升遗传算法效率的基础上生成可行的反制方案;最后设计联盟形成规则,通过联盟之间的成员变动使各联盟达到纳什稳定状态,在算子数量较多的情况下仍能使反制方案被持续稳定优化。仿真对比实验表明所提策略具有可行性和优越性,能在目标遭受饱和攻击时提供合理高效的反制方案,可为大规模跨域无人集群作战研究提供参考。

基于多特征相似度的空中目标聚类研究

为准确识别空战场敌方目标的编队信息,本文提出一种针对空中目标的聚类模型,综合选取空中目标的位置、高度、航向、航速等多维度信息,计算目标之间的相似度,构建多特征相似度矩阵,将多特征相似度作为目标之间“距离”的度量方式,通过K-means算法聚类迭代,得到空中目标的编队信息。通过仿真实验,验证了本文所提方法在复杂空战场环境下,能准确识别敌目标的编队信息,相比传统聚类算法,识别准确率提高40%,有较好的工程应用价值。

基于兵棋推演的空战编组对抗智能决策方法

基于兵棋研究的空战编组对抗方法主要使用规则或运筹等手段,存在假设不够合理、建模不准确、应变性差等缺陷。强化学习算法可以根据作战数据自主学习编组对抗策略,以应对复杂的战场情况,但现有强化学习对作战数据要求高,当动作空间过大时,算法收敛慢,且对仿真平台有较高的要求。针对上述问题,提出了一种融合知识数据和强化学习的空战编组对抗智能决策方法,该决策方法的输入是战场融合态势,使用分层决策框架控制算子选择并执行任务,上层包含使用专家知识驱动的动作选择器,下层包含使用专家知识和作战规则细化的避弹动作执行器、侦察动作执行器和使用强化学习算法控制的打击动作执行器。最后基于典型作战场景进行实验,验证了该方法的可行性和实用性,且具有建模准确、训练高效的优点。

核准制下超超临界火电机组NO_(x)排放特性的数值模拟

围绕新建火电项目核准制度,以某新建超超临界火电机组1000 MW四墙切圆燃煤锅炉为研究对象,运用FLUENT数值计算软件对其进行1:1实体建模,选择对应的数学模型,采用数值模拟的方法对燃煤锅炉在不同过量空气系数、磨煤机组合方式以及锅炉负荷率下的NO_(x)生成特性规律进行了研究。结果表明:炉内过量空气系数在1.1~1.15时可取得较低的NO_(x)排放及较高的燃烧效率。6层燃烧器全部投运工况下,锅炉燃烧NO_(x)生成量较多,投运5层燃烧器时,磨煤机组合方式为ABCDE可取得最低的NO_(x)排放,组合方式为BCDEF时NO_(x)排放浓度最高。随负荷减小炉内温度下降,NO_(x)生成量减少,而气流组织和燃尽度较差。