Combustion and NO_x Emission Behavior of Chinese Coals

Seven Chinese coals ranking from anthracite to sub-bituminous fromthe Shanxi province were selected for study to forecast thecombustion and NO_x emission behavior. Three UK, one Indonesia andone South Africa coal was included in the study for reference. A flatflame-turbulent jet apparatus was employed to assess flame stability,ignition performance and NO_x emission behavior for the initial stageof devolatilization and combustion. This apparatus can simulateparticle heating rates, maximum temperatures and the influence of theturbulent Fluid interactions on the fate of volatiles.

基于物理信息神经网络的燃煤锅炉NO_x排放浓度预测方法

准确的NO_(x)浓度预测对保障燃煤锅炉安全运行和降低污染物排放具有重要意义。基于机器学习的NO_x排放浓度预测方法计算速度快、拟合精度高,但缺少可解释性,且过度依赖训练样本,在样本不充分的情况下模型泛化能力差。为此,该文提出一种基于物理信息神经网络的燃煤锅炉NO_x排放浓度预测方法,将煤量、氧量、分离燃尽风(separated overfireair,SOFA)开度与NO_x排放浓度之间的单调关系嵌入到神经网络中,促使模型服从机理约束,避免机器学习过拟合或欠拟合,提升模型在锅炉宽工况条件下的准确性。以某660 MW燃煤锅炉为研究对象,算例分析表明,提出的预测方法明显优于随机森林、支持向量机和神经网络等常规机器学习方法,即使在未知工况下也能遵循参数间单调性关系,具有较好的可解释性和泛化能力。

Advances in reduction of NO_x and N_2O emission formation in an oxy-fired fluidized bed boiler

Fossil fuel combustion is one of the major means to meet the mounting global energy demand. However, the increasing NO_x and N_2 O emissions arising from fossil fuel combustion process have hazardous effects. Thus, mitigating these gases is vital to attain a sustainable environment. Interestingly, oxy-fuel combustion in fluidized bed for carbon capture and minimized NO_x emissions is strongly sustainable compare to the other approaches. It was assessed that NO_x formation and fuel-N conversion have significant limitation under oxy-fluidized bed compared to air mode and the mechanism of NO_x formation is still deficient and requires further development. In addition, this review paper discussed the potential of primary measure as low emission process with others supplementary techniques for feasible NO_x reduction. The influences of combustion mode, operating parameters, and reduction techniques such as flue gas recirculation, oxygen staging, biomass co-firing, catalyst, influence of fluidized bed design and structure, decoupling combustion and their merges are respectively evaluated. Findings show that significant minimization of NO_x emission can be achieved through combination of primary and secondary reduction techniques.

Impacts of Future NO_x and CO Emissions on Regional Chemistry and Climate over Eastern China

A coupled chemical/dynamical model （SOCOL-SOlar Climate Ozone Links） is applied to study the impacts of future enhanced CO and NO_x emissions over eastern China on regional chemistry and climate. The result shows that the increase of CO and NOx emissions has significant effects on regional chemistry, including NOx, CO, O_3, and OH concentrations. During winter, the CO concentration is uniformly increased in the northern hemisphere by about 10 ppbv. During summer, the increase of CO has a regional distribution. The change in O_3 concentrations near eastern China has both strong seasonal and spatial variations. During winter, the surface O_3 concentrations decrease by about 2 ppbv, while during summer they increase by about 2 ppbv in eastern China. The changes of CO, NO_x, and O_3 induce important impacts on OH concentrations. The changes in chemistry, especially O_3, induce important effects on regional climate. The analysis suggests that during winter, the surface temperature decreases and air pressure increases in central-eastern China. The changes of temperature and pressure produce decreases in vertical velocity. We should mention that the model resolution is coarse, and the calculated concentrations are generally underestimated when they are compared to measured results. However, because this model is a coupled dynamical/chemical model, it can provide some useful insights regarding the climate impacts due to changes in air pollutant emissions.

Strategic Study on the Development of Space Science in China and Proposals for Future Missions

Since 2011,the Chinese Academy of Sciences(CAS)has implemented the Strategic Priority Program on Space Science(SPP).A series of scientific satellites have been developed and launched,such as Dark Matter Particle Explorer(DAMPE),Quantum Experiments at Space Scale(QUESS),Advanced Space-based Solar Observatory(ASO-S),Einstein Probe(EP),and significant scientific outcomes have been achieved.In order to plan the future space science missions in China,CAS has organized the Chinese space science community to conduct medium and long-term development strategy studies,and summarized the major scientific frontiers of space science as“One Black,Two Dark,Three Origins and Five Characterizations”.Five main scientific themes have been identified for China’s future breakthroughs,including the Extreme Universe,Space-Time Ripples,the Panoramic View of the Sun and Earth,the Habitable Planets,and Biological&Physical Science in Space.Space science satellite missions to be implemented before 2030 are proposed accordingly.

Fast solution to the free return orbit's reachable domain of the manned lunar mission by deep neural network

It is important to calculate the reachable domain(RD)of the manned lunar mission to evaluate whether a lunar landing site could be reached by the spacecraft. In this paper, the RD of free return orbits is quickly evaluated and calculated via the classification and regression neural networks. An efficient databasegeneration method is developed for obtaining eight types of free return orbits and then the RD is defined by the orbit’s inclination and right ascension of ascending node(RAAN) at the perilune. A classify neural network and a regression network are trained respectively. The former is built for classifying the type of the RD, and the latter is built for calculating the inclination and RAAN of the RD. The simulation results show that two neural networks are well trained. The classification model has an accuracy of more than 99% and the mean square error of the regression model is less than 0.01°on the test set. Moreover, a serial strategy is proposed to combine the two surrogate models and a recognition tool is built to evaluate whether a lunar site could be reached. The proposed deep learning method shows the superiority in computation efficiency compared with the traditional double two-body model.

Influence of constricted air distribution on NO_x emissions in pulverized coal combustion boiler

This paper reports a field testing of full scale PCC (Pulverized Coal Combustion) boiler study into the influence of constricted air distribution on NO x emissions at unit 3 (125 MW power units, 420 t/h boiler) of Guixi power station, Jiangxi and puts forward the methods to decrease NO x emissions and the principle of boiler operation and regulation through analyzing NO x emissions state under real running condition. Based on boiler constricted air distribution, the experiment mainly tested the influence of primary air, excessive air, boiler load and milling sets (tertiary air) on NO x emissions and found its influence characteristics. A degraded bituminous coal is simply adopted to avoid the test results from other factors.

A Planning Method for Operational Test of UAV Swarm Based on Mission Reliability

The unmanned aerial vehicle(UAV)swarm plays an increasingly important role in the modern battlefield,and the UAV swarm operational test is a vital means to validate the combat effectiveness of the UAV swarm.Due to the high cost and long duration of operational tests,it is essential to plan the test in advance.To solve the problem of planning UAV swarm operational test,this study considers the multi-stage feature of a UAV swarm mission,composed of launch,flight and combat stages,and proposes a method to find test plans that can maximize mission reliability.Therefore,a multi-stage mission reliability model for a UAV swarm is proposed to ensure successful implementation of the mission.A multi-objective integer optimization method that considers both mission reliability and cost is then formulated to obtain the optimal test plans.This study first constructs a mission reliability model for the UAV swarm in the combat stage.Then,the launch stage and flight stage are integrated to develop a complete PMS(Phased Mission Systems)reliability model.Finally,the Binary Decision Diagrams(BDD)and Multi Objective Quantum Particle Swarm Optimization(MOQPSO)methods are proposed to solve the model.The optimal plans considering both reliability and cost are obtained.The proposed model supports the planning of UAV swarm operational tests and represents a meaningful exploration of UAV swarm test planning.

Life Origin in the Milky Way Galaxy: II. Scanning for Habitable Stellar Systems on Behalf of Future Space Missions

The possibility of the life origin in the stellar systems, located at a distance of ~200 pc from the solar system, was investigated. The stars, in the spectrums of which C (carbon), O (oxygen), N (nitrogen), and P (phosphorus) are found, are called DNA-stars. Based on stellar abundances a new method for searching for habitable exoplanets has been developed and a list of 48 DNA-stars in the solar neighborhood, on which life is possible, has been defined. The quota of DNA-stars is equal 1.3% of the total amount of Hypatia Stellar Catalog. Only three DNA-stars out of selected 48 stars belong to the spectral class as our Sun (G2V). The closest to the solar system is the DNA-star with the number HIP 15510, which belongs to the G8V class and is 6 pc away from the solar system. Nine DNA-stars, which have the highest chemical similarity with solar spectrum, were identified. It is identified that one of these nine stars, HIP 24681, has six planets.

“Einstein Probe”Mission Holds New Promise in Time-domain Astronomy

Einstein Probe,an astronomical satellite designed for X-ray observation on astronomical events drastically evolving over time,was successfully sent into preset orbit by a Long March 2C rocket from China’s Xichang Satellite Launch Center located in Sichuan Province at 15:03 GMT+8 on January 9,2024.

Key networks to create disaster resilient Smart Cities Mission: A case for remodeling India’s Smart Cities Mission to include disaster resilience

Amidst a concerning surge in urban losses attributed to disasters,this research paper explores the intricate relationship between urban development,disaster mitigation,and resilience emphasizing the significance of addressing disaster vulnerability in urban settings,where a substantial portion of the population faces risks stemming from high population density,limited resilience,and inadequate coping capabilities.The study advocates for the integration of disaster resilience principles into the Smart Cities Mission of India,placing particular emphasis on the necessity of developing infrastructure,establishing early warning systems,and fostering community engagement to bolster urban resilience.Furthermore,the paper draws comparisons and parallels between the components of smart cities,mitigation strategies,and disaster resilience,illuminating their interconnectedness and potential synergies.In conclusion,the study recommends the incorporation of essential network elements to establish a Smart Cities Mission that is resilient to disasters,ultimately aiming to safeguard urban communities from the adverse impacts of future calamities.

基于动态相关向量回归的燃煤锅炉烟气NO_x浓度预测模型

针对NO_x的生成过程的高度非线性、强相关性以及动态特征,提出一种基于互信息和动态相关向量回归的烟气NO_x浓度预测模型。依托某660 MW燃煤锅炉的历史运行数据,建立动态相关向量回归模型。通过和相关向量回归、人工神经网络、极限学习机模型以及动态支持向量回归模型对比分析,提出的NO_x浓度预测模型动态跟踪性能好,预测准确性高,为锅炉燃烧参数调整和SCR系统动态优化提供了基础。

不确定环境下多无人机察打一体任务规划方法

针对动态不确定战场环境下多无人机对多区域、多目标的协同察打任务规划过程中存在的信息不确定、任务多约束及航迹强耦合的多目标优化与决策问题,结合Dubins航迹规划算法,提出了一种融合多种改进策略的灰狼优化算法(grey wolf optimization algorithm incorporating multiple improvement strategies,IMISGWO).首先,针对动态环境带来的无人机巡航速度及察打任务消失时间的不确定性,基于可信性理论建立了以最大化任务收益为指标的任务规划数学模型;其次,为实现该问题的快速求解,设计了初始解均匀分布、个体通信机制调整、动态权重更新和跳出局部最优等策略,提升算法解搜索能力;最后,构建了多无人机察打一体典型任务仿真场景,通过数字仿真以及虚实结合半实物仿真试验验证了算法的可行性和有效性.仿真结果表明:算法在求解不确定环境下耦合航迹的多无人机察打一体任务规划问题时,能够生成多机高效的任务执行序列和满足无人机飞行性能约束的飞行轨迹,且能够适用于无人机数量增加导致问题复杂度增加情形下此类问题的求解.

新工科背景下“无人机地面站与任务规划”课程设计

“无人机地面站与任务规划”作为无人驾驶航空器系统工程专业的一门核心专业课程,探讨在“新工科”建设背景下课程具体内容,通过理论教学与研究实验实践教学相结合的方式进行课程设计,以顺应时代要求和人才培养需求。该研究可为无人机相关专业课程建设提供借鉴。

低NO_x煤粉燃烧器技术的研究进展与前景展望

针对日益严格的氮氧化物排放标准,从直流燃烧和旋流燃烧两个方面,介绍了目前国内外较先进的低NOx煤粉燃烧器的技术特点、应用状况及其优缺点,从而提出进一步研究的方向,以开发适应我国国情的低NOx煤粉燃烧器。

不同温度下炉内喷射氨水脱除NO_x的模拟与试验研究

在一台小型沉降炉上进行了氨水喷射还原烟气中NOx的SNCR(SelectiveNon CatalyticReduction)实验研究,同时结合化学反应动力学模型研究了NH3还原NO过程中的关键影响因素,结果发现,过高的温度引起氨水的氧化,过低的温度不利于NO的还原,存在一个单一的温度区间,在该试验台上最佳的氨水喷射温度范围为850℃～1100℃,最高达到了82%的NO还原率;采用均相反应模型与试验结果进行了对比,在高温区吻合情况较好;当温度高于950℃时,NH3残留量可以忽略;NH2的两类支链反应对于整个反应起重要作用。

钼硅酸化学吸收同时去除气流中的SO_2和NO_x

对钼硅酸溶液脱除废气中的ＳＯ２和ＮＯ２及其吸收机理进行了研究．实验结果表明，钼硅酸能十分有效地吸收ＳＯ２并使杂多酸还原为杂多兰；而杂多兰则能还原ＮＯｘ为Ｎ２，从而达到同时去除ＳＯ２和ＮＯｘ的目的．

基于优化粗粒级固体燃料赋存形态的铁矿烧结过程NO_x减排

铁矿烧结工序作为钢铁行业NO_x排放的主要来源,在当前高压环保态势下减少其NO_x排放迫在眉睫.烧结过程NO_x主要产生于固体燃料燃烧过程,而粗粒级燃料的赋存形态会影响其NO_x排放.基于此,本研究采用可视化微型烧结燃烧装置研究裸露型和被覆型粗粒级焦粉的燃烧行为,以及优化其配加模式对NO_x排放和烧结固结强度的影响规律,并烧结杯实验研究兼顾NO_x减排和烧结产质量指标的适宜粗粒级燃料赋存形态.结果表明,相比裸露型粗粒级焦粉,表面被覆铁酸钙细粉时其NO_x排放降低约56%;分加粗粒级焦粉以调控其为裸露型时,NO_x排放增加约10%,且烧结矿强度降低,而控制粒度为0.5~3.15 mm以调控其为被覆型时,NO_x最大体积分数和N元素转化率分别降低约8%和27%,且烧结各项产质量指标均得到改善.

煤燃烧中NO_x的来源和抑制其生成的有效措施

煤燃烧中产生的ＮＯ＿ｘ是不可忽视的大气污染源。根据其生成机理，它主要来自煤中氮的氧化以及高温下空气中Ｎ＿２和Ｏ＿２的反应。烟气中ＮＯ＿ｘ的浓度范围很宽，从２００至２５００ｍｇ／ｍ￣３，影响因素有燃烧温度、空气过剩系数、煤种和燃烧器类型等。在煤燃烧中采取适当措施，可以有效地降低ＮＯ＿ｘ浓度，如降低燃烧温度、分段燃烧、优化空气过剩系数、烟气部分循环和选用含氨量低的煤等。

造纸污泥与废水污泥流化床焚烧时NO_x和SO_2的排放特性研究

The experimental studies on the formation of NOx and SO2 during incineration of sewagesludge and paper mill sludge are reported. The test result indicates that: (1) The conversionof fuel-S into SO2 and fuel-N into NOx is mainly determined by sludge characteristics;(2) Emission of NOx and SO2 decreases with increasing sludge moisture content, increaseswith increasing bed temperature and excess air; (3) The conversion of fuelN into NOxincreases with increasing excess air; (4) The conversion of fuel-S into SO2 increases with bedtemperature and excess air increasing, decreases with sludge moisture increasing.