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As the new crown epidemic has gradually become a normalized disease similar to the flu, people are paying more and more attention to remote work and learning. Companies such as meta have spotted the development of the remote social track, and positioned the overall development direction of the company as the research and development of the metaverse virtual space. During the epidemic, the school's population base was large, and the students' demand for distance learning was also large. In the current distance teaching, students' sense of participation, concentration, and learning effect were poor. With meta company's all-round research on virtual technology, VR and other technologies are rapidly being applied in various industries. Among them, the application of VR technology to the creation of virtual classrooms has become a research hotspot in academia, but the probability of exposure of students' personal information to virtual classrooms how to ensure the security of students' information while carrying out efficient teaching in virtual classrooms is the focus of this paper. This paper first introduces VR and blockchain technology and their corresponding applications, and then uses a questionnaire to obtain the current information security issues and teaching atmosphere of distance learning, and summarizes the current distance learning for students and teachers according to the questionnaire. needs and actual problems. Finally, combined with the characteristics of VR virtual technology, a virtual classroom is designed to solve the current problems of distance learning. After a simulation test, it was found that the distance teaching classroom using virtual reality technology can achieve the same or even better teaching effect than the traditional offline classroom. [ABSTRACT FROM AUTHOR]

Thermal analysis of Electric Machine for Electric Vehicles (EVs), is crucial for precisely predicting the temperature distribution. In the paper, for a forced-air cooled induction machine, two methods of thermal models analysis are compared with measurements. The first numerical method is Computational Fluid Dynamics (CFD) over Finite Element Method (FEM). And the second one uses Lumped ParameterMethod (LPM). For the analysis based on CFD over FEM, a 3D induction machine is modeled with force-air cooling housing. The air flow is simulated and the losses are calculated as heat source for thermal models. FEM is coupled with CFD to get the thermal field distribution. For the LPM, the equivalent thermal resistance of winding, the heat transfer coefficients of the airgap and forced air are calculated in the LP thermal model. Finally,Measurement results are determined by PT100 embedded in winding end, as well by infrared instrumentation for measuring the image on the shell thermal distribution. Experimental validation is presented and the conclusion can be drawn from comparing these aspects of two methods, providing some reference for the research applied in motor for EVs. [ABSTRACT FROM AUTHOR]

The hydroxyl radical (•OH) has a crucial function in the oxidation and removal of many atmospheric compounds that are harmful to health. Nevertheless, high reactivity, low atmospheric abundance, determination of hydroxyl, and hydroperoxyl radical's quantity is very difficult. In the atmosphere and troposphere, hydroperoxyl radicals (HO 2 ) are closely demanded in the chemical oxidation of the troposphere. But advances in technology have allowed researchers to improve the determination methods on the research of free radicals through some spectroscopic techniques. So far, several methods such as laser-induced fluorescence (LIF), high-performance liquid chromatography (HPLC), and chemical ionization mass spectroscopy have been identified and mostly used in determining the quantity of hydroxyl and hydroperoxyl radicals. In this systematic review, we have advised the use of scavenger as an advance for further researchers to circumvent some of these problems caused by free radicals. The primary goal of this review is to deepen our understanding of the functions of the most critical free radical (•OH, HO 2 ) and also understand the currently used methods to quantify them in the atmosphere and troposphere., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

The heterogeneous degradation of nitrogen dioxide (NO 2 ) on five samples of natural Icelandic volcanic particles has been investigated. Laboratory experiments were carried out under simulated atmospheric conditions using a coated wall flow tube (CWFT). The CWFT reactor was coupled to a blue light nitrogen oxides analyzer (NO x analyzer), and a long path absorption photometer (LOPAP) to monitor in real time the concentrations of NO 2 , NO and HONO, respectively. Under dark and ambient relative humidity conditions, the steady state uptake coefficients of NO 2 varied significantly between the volcanic samples probably due to differences in magma composition and morphological variation related with the density of surface OH groups. The irradiation of the surface with simulated sunlight enhanced the uptake coefficients by a factor of three indicating that photo-induced processes on the surface of the dust occur. Furthermore, the product yields of NO and HONO were determined under both dark and simulated sunlight conditions. The relative humidity was found to influence the distribution of gaseous products, promoting the formation of gaseous HONO. A detailed reaction mechanism is proposed that supports our experimental observations. Regarding the atmospheric implications, our results suggest that the NO 2 degradation on volcanic particles and the corresponding formation of HONO is expected to be significant during volcanic dust storms or after a volcanic eruption., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

The nitrate radical (NO 3 ) and dinitrogen pentoxide (N 2 O 5 ) play an important role in the nocturnal atmosphere chemistry. Observations of NO 3 radicals and N 2 O 5 were performed in a semirural ground site at Tai'Zhou in polluted southern China using cavity ring down spectroscopy (CRDS) from 23 May to 15 June 2018. The observed NO 3 and N 2 O 5 concentrations were relatively low, with 1 min average value of 4.4 ± 2.2 and 26.0 ± 35.7 pptV, respectively. The N 2 O 5 uptake coefficient was determined to be from 0.027 to 0.107 based on steady state lifetime method. Fast N 2 O 5 hydrolysis was the largest contributor to the loss of NO 3 and contributed to substantial nitrate formation, with an average value of 14.83 ± 6.01 µg/m 3 . Further analysis shows that the N 2 O 5 heterogeneous reactions dominated the nocturnal NO x loss and the nocturnal NO x loss rate is 0.14 ± 0.02 over this region., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

Reaction rate constants and products of 1-octen-3-one, 3-octen-2-one and 4-hexen-3-one with ozone were studied in a 100-L fluorinated ethylene propylene (FEP) Teflon film bag using absolute rate method at 298 ± 1 K and atmospheric pressure. The rate constants were (1.09 ± 0.12) × 10 -17 , (3.48 ± 0.36) × 10 -17 and (5.70 ± 0.60) × 10 -17  cm 3 /(molecule⋅sec), respectively. According to the obtained rate constants, the effects of carbonyl were discussed. The carbonyl group in β position has a net withdrawing effect with respect to an olefinic bond, then causing the decline of rate constants. The quantum chemical calculation was used to explain the results of rate constants. The products of ozonolysis were mainly aldehydes, which have significant influence on the formation of SOA, and hence play an important role in the atmosphere. In this work, we detected the main products of reaction and proposed the reaction mechanism by combining the results of quantum chemical calculations. Atmospheric lifetime for three unsaturated ketones reacted with ozone was 36.4, 11.4 and 6.9 hr for 1-octen-3-one, 3-octen-2-one and 4-hexen-3-one, respectively., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

In the buoyancy and turbulence-driven atmospheric circulations (BTDAC) that occur over urban areas where the approach means wind speeds are very low (less than turbulent fluctuations and typically <3m/sec), the surface temperatures are significantly higher than those in the external rural areas, and the atmosphere above the mixing layer is stably stratified. In this paper, the mechanisms of BTDAC formation are studied through laboratory experiments and modelling, with additional low-level inflow from external rural areas and a divergent outflow in the opposite direction in the upper part of the mixed layer. Strong turbulent plumes in the central region mix the flow between lower and higher levels up to the inversion height. There are shear-driven turbulent eddies and weaker buoyant plumes around the periphery of the urban area. As the approach flow is very weak, the recirculating streamlines within the dome restrict the ventilation, and the dispersion of pollution emitted from sources below the inversion height leading to a rise in the mean concentration. Low-level air entrained from rural areas can, however, improve ventilation and lower this concentration. This trend can also be improved if the recirculating structure of the BTDAC flow pattern over urban areas breaks down as a result of the surface temperature distribution not being symmetrical, or as the approach wind speed increases to a level comparable with the mean velocity of circulation, or (except near the equator) the urban area is large enough that the Coriolis acceleration is significant., (Copyright © 2017. Published by Elsevier B.V.)

This paper focused on the pollution characteristics, sources and lung cancer risk of atmospheric polycyclic aromatic hydrocarbons (PAHs) in a new urban district of Nanjing, China. Gaseous and aerosol PM 2.5 (particulate matter with aerodynamic diameter smaller than 2.5μm) samples were collected in spring of 2015. Sixteen PAHs were extracted and analyzed after sampling. Firstly, arithmetic mean concentrations of PAHs and BaP eq (benzo[a]pyrene equivalent) were calculated. The mean concentrations of PAHs were 29.26±14.13, 18.14±5.37 and 48.47±16.03ng/m 3 in gas phase, particle phase and both phases, respectively. The mean concentrations of BaP eq were 0.87±0.51, 2.71±2.17 and 4.06±2.31ng/m 3 in gas phase, particle phase and both phases, respectively. Secondly, diagnostic ratios and principal component analysis were adopted to identify the sources of PAHs and the outcomes were the same: traffic exhaust was the predominant source followed by fuel combustion and industrial process. Finally, incremental lung cancer risk (ILCR) induced by whole year inhalation exposure to PAHs for population groups of different age and gender were estimated based on a Monte Carlo simulation. ILCR values caused by particle phase PAHs were greater than those caused by gas phase PAHs. ILCR values for adults were greater than those for other age groups. ILCR values caused by total (gas+particle) PAHs for diverse groups were all greater than the significant level (l0 -6 ), indicating high potential lung cancer risk. Sensitivity analysis results showed that cancer slope factor for BaP inhalation exposure and BaP eq concentration had greater impact than body weight and inhalation rate on the ILCR., (Copyright © 2016. Published by Elsevier B.V.)

The exchange of CO_{2} between the atmosphere and the ocean surface is a problem that has become increasingly important due to its impact on climatic behavior. Given the large quantity of sources of information available for studying the CO_{2} problem, it is necessary to provide innovative solutions that facilitate the automation of certain tasks and incorporate decision support systems to obtain a better understanding of this phenomenon. This paper presents a multiagent architecture aimed at providing solutions for monitoring the interaction between the atmosphere and the ocean. The ocean surface and the atmosphere exchange carbon dioxide. This process is can be modeled by a multiagent system with advanced learning and adaption capabilities. The proposed multiagent architecture incorporates CBR-agents that integrate novel strategies that both monitor the parameters that affect the interaction, and facilitate the creation of models. The system was tested and this paper presents the results obtained. [ABSTRACT FROM AUTHOR]

The newly-developed cavity ring-down laser absorption spectroscopy analyzer with special calibration protocols has enabled the direct measurement of atmospheric vapor isotopes at high spatial and temporal resolution. This paper presents real-time hydrogen and oxygen stable isotope data for atmospheric water vapor above the sea surface, over a wide range of latitudes spanning from 38°N to 69°S. Our results showed relatively higher values of δ(18)O and δ(2)H in the subtropical regions than those in the tropical and high latitude regions, and also a notable decreasing trend in the Antarctic coastal region. By combining the hydrogen and oxygen isotope data with meteoric water line and backward trajectory model analysis, we explored the kinetic fractionation caused by subsiding air masses and related saturated vapor pressure in the subtropics, and the evaporation-driven kinetic fractionation in the Antarctic region. Simultaneous observations of meteorological and marine variables were used to interpret the isotopic composition characteristics and influential factors, indicating that d-excess is negatively correlated with humidity across a wide range of latitudes and weather conditions worldwide. Coincident with previous studies, d-excess is also positively correlated with sea surface temperature and air temperature (Tair), with greater sensitivity to Tair. Thus, atmospheric vapor isotopes measured with high accuracy and good spatial-temporal resolution could act as informative tracers for exploring the water cycle at different regional scales. Such monitoring efforts should be undertaken over a longer time period and in different regions of the world., (Copyright © 2014. Published by Elsevier B.V.)

The cumulative effects of seasonal Earth processes in different places and times in the atmosphere, hydrosphere, and cryosphere essentially and inevitably shape global climate conditions. Therefore, the article investigates the possibilities for modelling the periodicity of the observable seasonal climate processes. The starting assumption of the study is that the seasonal climate processes are representable by two-phase linear periodic models based on observed data. A numerical algorithm elaborated in the sequel makes it possible to accumulate the seasonal effects of two successively progressive and regressive process phases of periodic climate changes in time. The model first tackles the reported seasonal growth of the atmospheric CO2 concentration. Next, it considers the observed seasonal cryospheric melting and freezing processes of the Antarctica and Greenland ice sheets and of the Arctic sea ice. It also elaborates on the reported seasonal sea level rise. Finally, the article summarises the interactions of periodic climate processes and the global climate conditions in time scale. The reports on global temperature rise are only on an annual basis. The article also emphasises the importance of control over the seasonal worsening and recovery scenarios for more appropriate projections of climate policies to 2100. [ABSTRACT FROM AUTHOR]

Methane flux from the ornithogenic soils was preliminarily measured by closed chamber method on Xi-sha atoll, South China Sea during March 10 to April 11, 2003 for the first time. The CH4 flux ranged from -4226.7 microg/(m2 x h) to 226.3 microg/(m2 x h) at the observation sites on Dong Island. High atmospheric CH4 consumption was observed from the ornithogenic soils on sunny days. CH4 uptake rates showed the highest value after the midday and they had a strong positive correlation with soil temperatures. Under the same weather conditions, the CH4 fluxes were also observed from the intact and disturbed soils on Yongxing Island. Results showed that the intact soils with natural vegetation also showed high atmospheric CH4 consumption and the average flux was -141.8 microg/(m2 x h). However, disturbed soils via anthropogenic reclamation showed CH4 emissions and the average flux was 441.7 microg/(m2 x h). Therefore land use changes may have an important effect on the CH4 fluxes from the tropical ornithogenic soils. In addition, different observation sites show a high spatial variation in CH4 fluxes. The wetland in salt marsh showed the CH4 emission on Dong Island, and the dry soil sites all showed high atmospheric CH4 consumption, suggesting that CH4 fluxes were predominantly controlled by soil water regime. The effects of soil chemical properties on CH4 fluxes were also analyzed and discussed in this paper.

Surface ozone (O3) was measured at Oki Island (Japan), Cheju Island( South Korea), Lanyu Island (Taiwan Province, China), Cape D' Aguilar ( Hong Kong SAR) and Lin'an, Longfenshan, Waliguan (China mainland) during January 1994-December 1996 as a component of IGAC/APARE(International Global Atmospheric Chemistry/East Asia-North Pacific Regional Experiment). This paper gave a joint discussion on the observational results at these stations over the study region. Investigations showed that the average of surface O3, mixing ratios at the seven sites are 47.9 ± 15.8, 48.1 ± 17.9, 30.2 ± 16.4, 31.6 ± 17.5, 36.3 ± 17.5, 34.8 ± 11.5 and 48.2 ± 9.5 ppbv, respectively. Significant diurnal variations of surface O3 have been observed at Oki, Cheju, D'Aguilar, Lin' an and Longfenshan. Their annual averaged diurnal differences range from 8 to 23 ppbv and differ in each season. Surface O3 at Lanyu and Waliguan do not show strong diurnal variability. Seasonal cycles of surface O3 showed difference at the temperate and the subtropical remote sites. Oki has a summer minimum spring maximum, while Lanyu has a summer minimum-autumn maximum. The suburban sites at D'Aguilar and Lin'an report high-level O3, in autumn and low-level O3 in summer. Surface O, remains high in autumn and low in winter at the rural site Longfenshan. For the global background station Waliguan, surface O3, exhibits a broad spring-summer maximum and autumn-winter minimum. The backward air trajectories to these sites have shown different pathways of long-range transport of air pollution from East Asia Continent to North Pacific Ocean. Surface O3, was found to be strongly and positively correlated with CO at Oki and Lanyu, especially in spring and autumn, reflecting the substantial photochemical buildup of O3, on a regional scale. It is believed that the regional sources of pollution in East Asia have enhanced the average surface O3, concentrations in the background atmosphere of North Pacific. [ABSTRACT FROM AUTHOR]

Fatigue tests by using the glass ceramics under two kinds of environmental conditions: air and ion-exchange water. That is to say, for glass ceramic specimens with three collinear cracks that were introduced at different crack center distances by Vicker's indentation, fatigue tests in water environment were carried out under a four-point bending load. The results show that the time to failure for a glass ceramic specimen having small crystal grains was significantly shorter in the water environment than in the atmosphere, whereas in a glass ceramic specimen having large crystal grains, no difference due to the environment can be observed. The prediction of time to failure with crack interaction and crack coalescence was also carried out. The results were in good agreement with the experimental results. The validity of the proposed method of fatigue life prediction was confirmed. [ABSTRACT FROM AUTHOR]

The CO2 in the atmosphere is in contact with water vapor and rain droplets forming CO2 · H2O · HCO3 and CO²3. Global precipitation is about 505 x 1015 kg/a. Based on theoretical calculation for unpolluted air and measurement observations, we estimated that 100--270 x 1012 gC/a are scavenged from the air by global precipitation. This roughly equals carbon emissions from volcanic sources or 2-6 per cent of current CO2 emissions. An inventory-based estimate on carbon removal in northwestern Europe supports the above calculation on global scare. With increasing CO2 concentration in the air, precipitation scavenging may increase. [ABSTRACT FROM AUTHOR]

Abstract: In order to obtain some aerosol properties in Tibetan Plateau atmosphere, simultaneous measurements of aerosols by use of a sunphotometer and an aureolementer were performed in the summer of 1998 in Lhasa(29.65 degrees N, 91.13 degrees E). Optical depth, volume size distribution and phase-function of aerosols were obtained from the measurements. Religious activities can have an effect on optical depth in Lhasa. The daily average aerosol optical depth(lambda = 500 nm) is less than 0.2. The diurnal variations of aerosol optical depth are relatively small during the period of summer. The maximal value of the mode radius in the volume size distribution are about 0.4, 2.0 and 4. o micro pm. [ABSTRACT FROM AUTHOR]