This study conducted comprehensive measurements of key aerosol optical properties alongside concurrent monitoring of atmospheric photochemical pollution in urban Beijing during the summer of 2019. The primary objectives were to investigate aerosol optical properties, classification types, and assess their impacts on ozone photochemical formation in urban Beijing. The results showed that atmospheric aerosols in urban Beijing during the summer exhibited extinction characteristics marked by strong scattering and low absorption, which may indirectly promote ozone formation. Throughout the observation period, aerosol optical properties were identified as the primary factor influencing incremental ozone concentration (ΔO3) under conditions of low precursor concentrations. In both haze and ozone pollution episodes, the single scattering albedo (SSA) was consistently the leading contributor to ΔO3, particularly under haze-ozone co-pollution conditions. Among the four aerosol types, "Small particles low absorption mix" (Small/LA) and "Large particle low absorption mix" (Large/LA) accounted for 55.15 % and 35.17 % of total aerosols, respectively. Notably, Large/LA aerosols, formed by the mixing and aging of air masses affected by sea salt and urban pollution, showed strong scattering properties and contributed most significantly to ΔO3. Regions with high ΔO3 contributions were primarily located in the polluted urban agglomerations of southeastern Beijing and the Bohai region. These findings highlight the critical role of aerosol optical properties in ozone formation, underscoring the necessity of incorporating this factor into future integrated control strategies for aerosols and ozone.

Air pollution in China has shown significant improvement due to the strict implementation of emission control measures; however, pollution episodes caused by regional transport still occur frequently. This study investigates the three-dimensional distribution and transport mechanisms of PM2.5 in the Beijing-Tianjin-Hebei (BTH) region during the 2022 Beijing Winter Olympics, focusing on heavy pollution episodes before, during, and after the event. We integrated 34 LiDAR stations and surface monitoring data with six machine learning models (XGBoost, Random Forest, LightGBM, RNN, CNN-RNN, and CNN-BiLSTM) to reconstruct spatiotemporal PM2.5 dynamics. The CNN-BiLSTM model, with an R2 of 0.924, RMSE of 6.805 μg/m3, and MAE of 4.640 μg/m3, outperformed the others, benefiting from its dual capability to capture spatial and temporal dependencies. Based on the model results, distinct PM2.5 distribution patterns were identified across the three Olympic phases. During the pre-event period, high concentrations (∼180 μg/m3) were concentrated in the upper atmosphere (1 km above ground) south of BTH. In contrast, Beijing and Tianjin experienced near-surface pollution peaks during the event, likely driven by short-range transport. In the post-event phase, PM2.5 concentrations decreased overall, with pollutants transported southward under persistent northerly winds. Transport flux intensity (TFI) analysis highlighted key pollution pathways, with pre-event TFI peaking at 3.2 × 105 μg·m-1·s-1 in Beijing, event-phase TFI reaching 3.8 × 105 μg·m-1·s-1, and post-event TFI peaking at 7.8 × 105 μg·m-1·s-1. These findings underscore deep learning's role in PM2.5 inversion and reveal significant transregional pollution transport dynamics, offering insights for regional air quality management.

This study explores the spatiotemporal distribution and formation mechanisms of urban heat islands (UHIs) in Nanjing during summer, utilizing temperature data from 82 automatic weather stations (AWSs) distributed across five concentric zones. The results demonstrate the substantial impact of urbanization on UHI patterns, with industrial and densely populated areas exhibiting higher UHI intensity (UHII), while regions with natural landscapes such as mountains and water bodies display lower temperatures. The analysis reveals that the most pronounced night-time UHI effect occurs in the highly urbanized central zones, whereas the weakest effect is observed during midday. Transitional UHI phases are identified around sunrise and sunset, with increased long-wave radiation post-sunset amplifying the UHI effect. Additionally, this study underscores the directional characteristics of UHI distribution in Nanjing. Notably, Hexi New Town has emerged as a new high-temperature hotspot due to rapid urbanization, while Jiangning New Town and Xianlin Sub-City maintain lower temperatures owing to their proximity to agricultural and forested areas. By selecting representative AWSs from different zones, this study introduces a novel and practical method for calculating UHII. Although the approach has limitations in precision, it provides an accessible tool for UHI analysis and can be adapted for use in other cities. This research offers valuable insights into the influence of urban development on local climate and presents a practical framework for future UHI studies and urban planning strategies aimed at mitigating UHI effects.

The evaluation of the impact of meteorological conditions and anthropogenic emissions to PM2.5 concentrations is a subject of ongoing debetate, which holds significant importance in guiding the formulation and implementation of emission reduction policies. A new method, based on advection dispersion theory, has been developed to assess the impact of emission control measures and meteorological effects on the reduction of pollutant concentrations. This method involves classifying meteorological factors and utilizing the emission source intensity, which is characterized under various meteorological factors, to quantify the effects of meteorological factors and emission reduction on pollutant concentrations. Wind speed (WS), wind direction (WD), atmospheric stability (determined by cloud volume, solar radiation levels, surface wind speed) and mixed height are chosen as the key meteorological factors. Baoding City, situated within the Beijing -Tianjin -Hebei (BTH) region, is taken as an example in this study and is characterized by severe particle pollution. Due to the implementation of air pollution control measures from 2016 to 2020, the particulate pollution in this city has significantly reduced. The result of our method showed that despite the unfavorable conditions for pollutant dispersion during 2018 and 2021, the aggressive policies were estimated to have contributed to reductions in PM2.5 concentration. Specifically, there were reductions of 35.7, 19.6, 28.6, and 107.9 mu g/m3 in spring, summer, autumn, and winter, respectively, from 2015 to 2018. Additionally, reductions of 8.2, 14.9, 30.0, and 50.7 mu g/m3 were observed in the corresponding seasons from 2018 to 2021.

电子辐照在核技术应用产业中成为重要的一部分，低能电子束在废水处理、食品保鲜等方面应用越来越广，辐照的计量参数对于辐照质量至关重要。由于低于300keV的电子束剂量学相关标准尚未建立，参数测量都溯源至10MeV电子直线加速器，测量对象的不一致带来了系统性的偏差。本论文针对低于300keV的低能电子，开展了测试与模拟计算相结合的电子束能量测量方法研究，研制了基于量热法的吸收剂量测量装置，探究了吸收剂量与束流强度、位移速度等参数的关系。结果表明：通过阶梯叠层法剂量实验结合能量沉积曲线模拟的方式实现了低能电子能量参数的测量，通过量热法实现了低能电子吸收剂量参数的测量，测量不确定度为11%（k=2）。本研究为低能电子辐照工艺提供了可靠的计量保障。

X、γ射线个人剂量当量次级标准电离室系统主要用于复现个人剂量当量、完成个人剂量当量量值传递,是保障辐射防护领域个人剂量当量量值准确和人员安全的重要设备.重点研究自研X、γ射线个人剂量当量次级标准电离室系统的可靠性、环境适应性的设计并开展试验测试;试验结果表明,X、γ射线个人剂量当量次级标准电离室系统可靠性满足MTBF≥1000h的要求,系统贮存温度范围-10～50℃,工作温度范围10～40℃,相对湿度为40%～75%.该产品的各项通用质量特性符合计量级产品工作环境条件要求,可作为次级标准用于X、γ射线个人剂量当量的量值复现与量值传递.

Meteorological conditions play a key role in the occurrence and evolution of atmospheric complex pollution. Considering the different pollution formation mechanisms of PM2.5 and O3, statistical calculation and in-depth learning methods were used to construct the PM2.5 and O3 meteorological condition indexes based on long-term pollution meteorological observation data. A research method was developed to study the meteorological characteristics and impact contribution of atmospheric complex pollution by using the meteorological condition index, and quantitative analysis of the distribution and variation of pollution excluding the influence of regional meteorological differences was also conducted. The results showed that in the summer of 2021, the pollution meteorological conditions in the key regions in central and eastern China were generally worse in the north and better in the south(index:"2+26" cities>the border area of Jiangsu, Anhui, Shandong, and Henan>the Yangtze River Delta) and the worst in June and the best in July. The "double high" pollution began to appear when the PM2.5 meteorological condition index>30 and O3 meteorological condition index>100; meanwhile, the unfavorable meteorological conditions for O3 also promoted the increase in PM2.5 concentration, resulting in the frequency of "double high" increases with the increase in O3 meteorological condition index. Compared with that during the same period last year, ρ(PM2.5) of each region decreased by 3.9 μg·m-3, 3.3 μg·m-3, and 1.4 μg·m-3 due to the contribution of the improvement in the pollution meteorological conditions, which is nearly 58.5% on average of the total decrease in PM2.5 concentration. However, the change in O3 pollution meteorological conditions was better in the north and worse in the south, and the overall deterioration in the Yangtze River Delta Region led to approximately 2.8 μg·m-3 growth for the O3 concentration. The PM2.5 and O3 concentrations after excluding the impact of meteorological differences showed different distribution characteristics from the air quality monitoring, in which the high concentrations of PM2.5 were distributed along the Bohai Sea, the inter-provincial border, and the south of the region, whereas the high concentrations of O3 were concentrated along the Taihang Mountains, around Mount Tai, and in parts of the Yangtze River Delta. The daily concentration variations in a single city during a specific pollution control period could be used as a basis for evaluating the effectiveness of local supervision and control, which will provide a reference for the dynamic supervision and daily scheduling of local control management.

After a major nuclear accident occurs in a nuclear facility,it is of great signifi-cance to quickly enter the accident area to obtain the radiation distribution of the site of nuclear leakage and radioactive contamination.In order to overcome the traditional nuclear emergency monitoring methods,which are prone to radiation damage to person-nel,poor mobility and low efficiency,this paper designs and implements a UAV radia-tion monitoring system,which can quickly enter the sky over radioactive contaminated areas for radiation monitoring.The UAV radiation monitoring system mainly includes wide-range G-M counter tube,cerium bromide scintillator detector,data acquisition sys-tem and data transmission system.The above devices can be built on the UAV to meas-ure the real-time radiation dose rate and energy spectrum at 0-100 m low altitude.

In recent years, the concentrations of PM2.5 in urban ambient air in China have been declining; however, the strong atmospheric oxidation capacity (AOC) represents challenges to the further reduction of PM2.5 concentration and the continuous improvement of ambient air quality in China in the future, since the overall AOC is still at a high level. For this paper, based on ground observation data recorded in Beijing from 2016 to 2019, the variation in AOC was characterized according to the concentration of odd oxygen (OX = O3 + NO2). The concentrations of the primary and secondary components of PM2.5 were analyzed using empirical formulas, the correlation between AOC and the concentrations of secondary PM2.5 and the secondary inorganic components (SO42−, NO3−, NH4+, and SNA) in Beijing were explored, the impact of atmospheric photochemical reaction activity on the generation of atmospheric secondary particles was evaluated, and the impact of atmospheric oxidation variations on PM2.5 concentrations and SNA in Beijing was investigated. The results revealed that OX concentrations reached their peak in 2016 and reached their lowest point in 2019. The OX concentrations followed a descending seasonal trend of summer, spring, autumn, and winter, along with a spatial descending trend from urban observation stations to suburban stations and background stations. The degree of photochemical activity and the magnitude of the AOC have a large influence on the production of atmospheric secondary particles. When the photochemical reaction was more active and the AOC was stronger, the mass concentrations of the secondary generated PM2.5 fraction were higher and accounted for a higher proportion of the total PM2.5 mass concentrations. In the PM2.5 fraction, SNA accounted for 50.7% to 94.4% of the total mass concentrations of water-soluble inorganic ions in the field observations. Higher concentrations of the atmospheric oxidant OX in ambient air corresponded to a higher sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR), suggesting that the increase in AOC could promote the increase of PM2.5 concentration. Based on a relationship analysis of SOR, NOR, and OX, it was inferred that the relationship between OX and SOR and the relationship between OX and NOR were both nonlinear. Therefore, when establishing PM2.5 control strategies in Beijing in the future, the impact of the AOC on PM2.5 generation should be fully considered, and favorable measures should be taken to properly regulate the AOC, which would be more effective when carrying out further control measures regarding PM2.5 pollution.

质子水吸收剂量的准确定值具有重要意义.基于量热法研究建立了质子束水量热计,针对量热计中的惠斯通电桥开展研究,经测试该惠斯通电桥具有有效性.经分析,基于惠斯通电桥的质子束水量热计可用于质子水吸收剂量的绝对测量,为质子剂量监测提供技术保障,确保质子剂量监测结果准确可靠.

To establish the high-pressure ionization chamber products for dose rate monitoring of the environmental level γ ray, the design from the aspects of ionization chamber shell, detector, electronic system, etc. are optimized, to improve the environmental adaptability, electromagnetic compatibility and reliability of the equipment. According to the standard method, the general quality characteristics test was carried out at a third party. The test results showed that the working and storage temperature range of the product was -10 ℃-45 ℃; Humidity range ≤93% RH; It has certain anti-vibration and impact capacity, and meets the requirements of the severity level 2M1 of transport environmental conditions in GB/T 8993—1998; Electrostatic discharge immunity and radio frequency electromagnetic field radiation immunity in electromagnetic compatibility shall meet the relevant requirements of GB/T 17626-2—2018 and GB/T 17626-3—2016; The reliability meets the requirement of MTBF≥1 000 h. The environmental adaptability, electromagnetic compatibility and reliability of this product meet the requirements of meter-level products. It can be used as a portable radiation dosimeter in climatefree places. High pressure ionization chamber can be used as a high accuracy work measuring instrument for ambient level air kerma to carry out radiation dose monitoring.

Taking Shihezi City, a typical city on the northern slope of Tianshan Mountains, as the case, based on the ground conventional pollutant monitoring, meteorological observation, the LiDAR observation, and the mesoscale Weather Research and Forecast（WRF） model simulation results, the impact of meteorological parameters and boundary layer structure changes on the air quality in Shihezi City were comprehensively analyzed. The results showed that the seasonal differences of air quality in Shihezi City were quite significant, with the highest difference of 11.4 times of PM 2.5 concentrations between winter and summer, and the occurrence rate of air pollution episodes in December to February in winter is as high as 81.2%, with 59.1% of heavy and above polluted days. In the winter of 2020-2021, four heavy pollution processes occurred, and each heavy pollution process lasted for 7-27 d, with the interval period of only 1-3 d. Each process was dominated by fine particle pollution. In total, the period of December-February could be considered as a continuous "pollution season", with the peak value of 373-425 μg/m~3 of PM 2.5 , and the average value of 0.82 for PM 2.5 /PM 10 . After entering autumn and winter, the continuous low temperature and high humidity meteorological conditions on the ground had a significant negative effect on PM 2.5 concentration, and the main influence conditions were T＜-3 ℃ and 65%＜RH＜92%. Under these conditions, the significant declining of boundary layer height and the change of near-ground diffusion caused by continuous strong inversion were the fundamental reasons for the formation of winter "pollution season". In the heavy pollution process on January 16-22, 2021, the continuous low temperature, high humidity and breezy/still wind conditions were the dominant ground meteorological conditions, and the generation and dissipation of heavy pollution only changed with the boundary layer and inversion conditions. The boundary layer height in the pollution accumulation period decreased by nearly 5 times compared with that in the clean days, and the intensity of the inversion temperature exceeded 1.5 ℃/（100 m）. Immediately after the heavy pollution episode, 3 clean days appeared following with the receding of inversion temperature and the rising of boundary layer height.

Atmospheric aerosols directly or indirectly affect the concentrations of other atmospheric components (e.g., ozone) through radiative effects and their surface chemistry, therefore studies on the optical and radiative properties of aerosols could provide effective information for atmospheric environmental pollution control. In this study, key optical parameters of aerosols and comprehensive observation of atmospheric photochemistry in urban areas of Beijing were carried out in summer in 2019 to investigate the aerosol optical properties, potential sources, and their effects on ozone photochemical formation mechanisms in the typical urban area of Beijing. The results showed that the aerosols in the urban area of Beijing had strong scattering properties in summer, and the classification of aerosols showed that moderately scattering fine-mode aerosols (24.58%) accounted for the largest percentage. High relative humidity (RH) environment further enhanced the scattering ability of scattering aerosols, but had no such effect on the absorbing aerosols. The contribution of regional transport to PM 2.5 was more significant than that of local sources in Beijing, which was mainly influenced by Hebei, Tianjin and Shandong, where the aerosols from this region were mainly fine-modal and had a strong scattering ability. The simulation results of NCAR MM indicated that the total incremental effect of ozone precursors and atmospheric aerosols on ozone formation was 6.26 ppbv for haze pollution episodes compared to clean days during the observation period. Single scattering albedo (SSA) and aerosol optical depth (AOD) were the dominant factors affecting ozone growth or reduction with the low concentration of nitrogen oxides (NO x ) and volatile organic compounds (VOCs), the mean contribution of extinction from SSA and AOD to ozone concentration increment were 11.25 and –3.94 ppbv, respectively. The results of this study could provide some reference for the development of synergistic PM 2.5 and ozone pollution prevention and control strategies.

空间电子环境地面模拟装置由1台电子直线加速器提供能量1～5 MeV范围内的电子,后续束流传输系统将电子束进行扩束处理.较大的能量范围对加速器的设计与运行条件提出了较高要求.本文主要阐述了该加速器的设计与实现过程,综合考虑了能量开关技术和束流负载效应,通过研究不同条件下的耦合度参数特性确定了加速管耦合度,分析提出了磁控管输出参数并进行了实验研究.加速器实验测试结果表明,电子束能量参数达到指标要求,为模拟装置提供了有效可靠的电子源.

The international research on radiation protection dosimetry mainly focuses on continuous radiation. However, pulsed radiation has been widely used in the fields of new detector development, radiographic inspection, X-ray diagnosis, nuclear accident emergency and scientific research, the measurement of pulsed dose (rate) is very difficult. In order to solve the technical problem of pulse response test of active radiation dosimeter, the generation principle of pulsed X-ray and gamma ray radiation field is discussed, and the reference radiation field of pulsed X-ray is established based on three kinds of X-ray machines. Combined with the secondary standard ionization chamber and pulse width measurement system, the research of pulsed radiation dose (rate) measurement technology is carried out. The experimental results show that the pulse width of the established pulsed X-ray reference radiation field can be adjusted between 50 ns-10 s, and the instantaneous dose rate range is 2.5 mSv/h-6.7 × 105 Sv/h, which can be widely used to study the pulsed X-ray response characteristics of active radiation dosimeter. This work can be widely used to study the pulsed X-ray response characteristics of active radiation dosimeter, which is of great significance to solve the calibration problem of pulsed radiation dose monitoring instrument.

The atmospheric aerosol particles have a potential heavy burden on environment, climate, and human health, which were closely related to the surface physicochemical properties. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) technique is a powerful tool to obtain detailed surface chemical information since it has high surface sensitivity for both elements and molecular ions, and high mass resolution. In this work, size-fractioned aerosol particles in the range of 0.43-10 mm during a severe haze episode in Beijing were analyzed by TOF-SIMS, the variation characteristics of chemical species corresponding to particle size and air pollution level was investigated by the normalization of secondary ion intensities, the possible sources were identified through principal component analysis (PCA), and the influence of meteorological factors and air mass transmission were also investigated. The study results showed that the surface chemical components of PM2.5 were more complicated during haze episode than on clean days. A total of 17 organic and inorganic species were detected, including crustal elements, heavy metals, sulfate, nitrate, siliceous compounds, hydrocarbons, oxygen-containing organics, and nitrogen-containing organics. In general, the particle surface mainly contained crustal elements, hydrocarbons, and carbon-containing inorganics. Organic and secondary ions significantly increased in heavy-polluted days, indicating the aging process of particles. Inorganic compounds had a higher percentage in coarse mode, while organic compounds were higher in accumulation mode. PCA results indicated that urban aerosol during this haze episode mainly came from vehicle emissions (24.7%), coal-fired combustion (22.4%), organic aerosol (19.3%), and dust resuspension (19.6%). The northern air mass could facilitate the dilution of air pollutants with the surface secondary formed components of particles significantly decreased. (c) 2022 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

To study the new type of dosimeter with a dose up to the ultra-high dose range of MGy, the electron spin resonance (ESR) method is used to measure the signal intensity of the sample irradiated by gamma rays or electron beams. Preliminary studies have been carried out through the selection of sensitive materials, linearity after irradiation, and stability. The results showed that the quartz can be used as a raw material for ultra-high dosimeters. After 15 min 300 ℃ proper heat treatment, the signal intensity of the irradiated quartz sample can maintain good stability within one year with a change of less than 3%. The radiation dose and the E′ signal intensity of quartz are proportional to the dose range of 10-103 kGy. The fitting coefficient is above 0.99. Compared with the high-purity quartz sample without heat treatment, the stability and R2 of fitting function of quartz sample are significantly improved. Therefore, the quartz dosimeter is suitable as a working dosimeter in the ultra-high dose range.

The Beijing area experienced daily ozone increases after the Belt and Road Forum in May 2017, with the maximum hourly O-3 peak exceeding 400 mu g/m(3). The high O-3 event was analyzed by using observed data and model simulations. Results indicated that the local photochemistry was the major driver boosting O-3 formation for northern suburban sites and regional transport in the late afternoon made another peak in O-3 diurnal variation for urban sites. A prominent VOC-limited sensitivity regime was dominant in the Beijing area, even over suburban areas far away from the Beijing urban center. The rapid increase in VOCs emissions from both biogenic and anthropogenic sources under high air temperatures provided the needed VOCs for O-3 formation, resulting in a dramatic O-3 increase after the summit. It was also found that PM2.5 experienced steady daily increases after the summit, leading to a gradual decrease in the UV radiation measured at the ground; however, O-3 showed a dramatically increasing trend, in contrast to the expectation that the high-level PM2.5 would restrain the O-3 formation by the theoretical deduction in the O-3 and aerosol interaction. The results suggest that the abrupt change in emissions during the study period overwhelmed the effects of the O-3 and aerosol interaction. Such temporary changes in emissions should be considered in mitigation strategies of O-3 control.

中国原子能科学研究院建立了一台DZ-12/4多能量档电子直线加速器,该装置主要用作辐射加工级电子束辐照实验平台.为了检测该电子束辐照实验平台辐照工艺控制参数,本文利用中国原子能科学研究院FJL-02型辐射变色薄膜剂量计对DZ-12/4多能量档电子直线加速器关键参数能量进行了测量,并对研制的束流监测系统法拉第筒的可靠性进行了验证.结果表明,DZ-12/4多能量档电子直线加速器能量在4～12 M eV范围可调,运行参数准确可靠;日常运行中,加速器运行人员通过监测设备和调节加速器参数可有效控制并估计辐照剂量,具有非常好的实用性和简便性.

为了准确、方便地测量辐射加工用低能电子加速器能量,采用射程法测量电子束能量,设计加工了两种不同类型的聚苯乙烯材料的楔形模体和叠层模体,结合辐射变色薄膜剂量计测量装置,利用两种能量测量模体同时测量标称能量为0.65MeV的加速器电子束能量,结果表明,设计的楔形模体可以测量能量低至0.65MeV的电子束能量.相比于叠层能量测量方法,楔形模体测量方法更为方便,效率更高,引入的不确定度更小.实践中射程法测量0.65MeV以上低能电子束能量时,推荐楔形能量测量模体测量电子束能量.