The impacts of modeling global CO2 concentrations with GEOS-Chem using different ocean carbon fluxes

The rise in atmospheric carbon dioxide(C02)concentrations caused by human activities is leading to global climate change,which poses a threat to human development and survival.This study analyzed the distribution of the ocean carbon flux with interannual changes and compared it with the climatological ocean carbon flux to deepen our understanding of carbon sources and sinks.To simulate global CO2 concentrations for the years2008-2010,the ocean carbon flux with interannual changes and the climatological ocean carbon flux were used to drive the GEOS-Chem model,an atmospheric chemical transport model.The simulated values were compared with the CO2 concentrations at nine observation stations to explore the influence of interannual changes in the ocean carbon fluxes on the simulated CO2 concentrations.The authors found that the difference between the two simulation results was greater in the Southern Hemisphere all year,and the difference in autumn was the largest.Compared with the observations,the simulated CO2 concentration of the ocean carbon flux with interannual changes is closer to the observations,indicating that this simulation is more accurate.

Characteristics of Suspended Sediment Concentrations over the Areas Adjacent to Changjiang River Estuary, the Summer of 1998

A major flood event occurred within the drainage basin of the Changjiang River in June-August, 1998. Survey over the East China Sea adjacent to the Changjiang River estuary shows that during the flood the turbid water (with a suspended sediment concentration of higher than 10 mg l-1) °°′reached 123E. Stratification of the concentration layers was present near 12215E, with the concentration in the bottom layer being 3 times that in the upper layer, in response to sediment °°settling processes. The concentration is the lowest in the area of 126E^127E, representing a characteristic of the Kuroshio water. Although there was some expansion of the turbid water extension compared with the winter situations with low freshwater discharges, the suspended sediment does not appear to disperse towards the northeast from the Changjiang River. Further, several secondary high suspended sediment concentration centers were present on the East China Sea continental shelf, which may result from resuspension of the seabed sediment or advection of seawater containing suspended matter. In order to understand the processes of fine-grained sediment transport/deposition and their impact on the flux of chemical constituents on the shelf, further studies on the hydrodynamics, temperature, salinity and nutrient characteristics are required.

Effects of an Urban Park and Residential Area on the Atmospheric CO_2 Concentration and Flux in Seoul,Korea

The CO2 concentrations and fluxes over an urban forest site （Namsan） and an urban residential region （Boramae） in Seoul, Korea, during the non-growing season （2 4 March 2011）, the growing season （10-12 June 2011）, and the late-growing season （22-24 September 2011） were analyzed. The CO2 concentrations of two sites showed nearly the same diurnal variation, with a maximum value occurring during the night and a minimum value occurring during daytime, as well as the same seasonal variation, with a maximum value during the non-growing season （early spring） and a minimum value during the growing season （summer）. The CO2 flux over the urban forest did not show any typical diurnal variation during the non-growing season, but did show diurnal variation with a small positive value during the night and a large negative value during daytime in the growing and late-growing seasons due to photosynthesis in the urban forest. The CO2 flux over the urban residential region showed a positive daily mean value for all periods, with large values during the non-growing season and small values during the growing season, and it also showed diurnal variation with two maxima at 0600-1000 LST and 1800-2400 LST, and two minima at 0300-0600 LST and 1100-1500 LST, and was strongly correlated with the use of liquefied natural gas for cooking and heating by surrounding houses.

Carbon Dioxide Concentration and Flux in an Urban Residential Area in Seoul,Korea

The carbon dioxide （CO2） concentrations and fluxes measured at a height of 17.5 m above the ground by a sonic anemometer and an open-path gas analyzer at an urban residential site in Seoul, Korea from February 2011 to January 2012 were analyzed. The annual mean CO2 concentration was found to be 750 mg m-3, with a maximum monthly mean concentration of 827 mg m-3 in January and a minimum value of 679 mg m-3 in August. Meanwhile, the annual mean CO2 flux was found to be 0.45 mg m-2 s-1, with a maximum monthly mean flux of 0.91 mg m-2 s-1 in January and a minimum value of 0.19 mg m-2 s-1 in June. The hourly mean CO2 concentration was found to show a significant diurnal variation; a maximum at 0700-0900 LST and a minimum at 1400-1600 LST, with a large diurnal range in winter and a small one in summer, mainly caused by diurnal changes in mixing height, CO2 flux, and surface complexity. The hourly mean CO2 flux was also found to show a significant diurnal variation, but it showed two maxima at 0700-0900 LST and 2100-2400 LST, and two minima at 1100-1500 LST and 0300-0500 LST, mainly caused by a diurnal pattern in CO2 emissions and sinks from road traffic, domestic heating and cooking by liquefied natural gas use, and the different horizontal distribution of CO2 sources and sinks near the site. Differential advection with respect to wind direction was also found to be a cause of diurnal variations in both the CO2 concentration and flux.

Numerical Simulation of CO_2 Concentrations in East Asia with RAMS-CMAQ

The regional air quality modeling system RAMS-CMAQ(Regional Atmospheric Modeling System and Models-3 Community Multi-scale Air Quality) was developed by incorporating a vegetation photosynthesis and respiration module(VPRM) and used to simulate temporal-spatial variations in atmospheric CO2 concentrations in East Asia,with prescribed surface CO2 fluxes(i.e.,fossil fuel emission,biomass burning,sea-air CO2 exchange,and terrestrial biosphere CO2 flux).Comparison of modeled CO2 mixing ratios with eight ground-based in-situ measurements demonstrated that the model was able to capture most observed CO2 temporal-spatial features.Simulated CO2 concentrations were generally in good agreement with observed concentrations.Results indicated that the accumulated impacts of anthropogenic emissions contributed more to increased CO2 concentrations in urban regions relative to remote locations.Moreover,RAMS-CMAQ analysis demonstrates that surface CO2 concentrations in East Asia are strongly influenced by terrestrial ecosystems.

System design and measurements of flux concentrator and its solid-state modulator for CEPC positron source

Positron sources are one of the most important components of the injector of a circular electron positron collector(CEPC).The CEPC is designed as an e^(+)e^(−)collider for a Higgs factory.Its accelerator system is composed of 100-km-long storage rings and an injector.The design goal of the positron source is to obtain positron beams with a bunch charge of 3 nC.The flux concentrator(FC)is one of the cores of the positron source.This paper reports the design,development,and measurements of an FC prototype system.The prototype includes an FC and an all-solid-state high-current pulse modulator.Preliminary tests show that the peak current on the FC can reach 15.5 kA,and the peak magnetic field can reach 6.2 T.The test results are consistent with the theoretical simulation.The FC system fulfills the requirements of the CEPC positron source as well as provides a reference for the development of similar devices both domestically and abroad.

Comparison of depth-averaged concentration and bed load flux sediment transport models of dam-break flow

This paper presents numerical simulations of dam-break flow over a movable bed. Two different mathematical models were compared: a fully coupled formulation of shallow water equations with erosion and deposition terms(a depth-averaged concentration flux model), and shallow water equations with a fully coupled Exner equation(a bed load flux model). Both models were discretized using the cell-centered finite volume method, and a second-order Godunov-type scheme was used to solve the equations. The numerical flux was calculated using a Harten, Lax, and van Leer approximate Riemann solver with the contact wave restored(HLLC). A novel slope source term treatment that considers the density change was introduced to the depth-averaged concentration flux model to obtain higher-order accuracy. A source term that accounts for the sediment flux was added to the bed load flux model to reflect the influence of sediment movement on the momentum of the water. In a onedimensional test case, a sensitivity study on different model parameters was carried out. For the depth-averaged concentration flux model,Manning's coefficient and sediment porosity values showed an almost linear relationship with the bottom change, and for the bed load flux model, the sediment porosity was identified as the most sensitive parameter. The capabilities and limitations of both model concepts are demonstrated in a benchmark experimental test case dealing with dam-break flow over variable bed topography.

CO_2 CONCENTRATION AND FLUX NEAR GROUND IN MARSH OF THE SANJIANG PLAIN OF NORTHEAST CHINA

There is limited information available on CO2 concentration and flux over marsh. The objective of this work was to characterize CO2 concentration and flux within and above marsh plant (Cares lasiocarpa Ehrh. and C. pseudoucuaica F. Schm) canopy at heights 0. 5, 1. 0 and 1. 5 m.CO2 concentration was measured sequentially every 3 bars by using an infrared gas analyzer. Soil and air temperature, wind speed, net radiation and soil heat flux were also measured simultaneously. Extremely drily minimum and maximum CO2 concentration rangal from 250 to 754 μmd/mol for the 4-year work. The typical minimum and maximum values ranged from 314 to 464 μmol/mol at the height of marsh plant (about 0. 5 m) during the fruiting perioed and mature date. The seasonal changes in CO2 concentration show that the minimum CO2 concentration occurred in the fruiting period and mature date, and both of their minimum values were 314 μmol/mol. This illustrates that CO2 consumed by photosynthesis was stable during the period. The flux of CO2 can be thought as a turbulent diffusion phenomenon. By micrometeorological methods, the diurnal CO2 fluxes were measured in the flowering peried, fruiting period, early mature date, late mature date and yellow-ripe stage. Their values were -0. 18, 38. 15,24. 13, 10. 9 and 4. 91 μmol/mol respectively.

Mapping Correlation Dimension along the Wall Region of a High-Flux Gas-Solid Riser Using Embedded Solid Concentration Time Series

Analysis of the entrance and wall dynamics of a high-flux gas-solid riser was conducted using embedded solid concentration time series collected from a 76 mm internal diameter and 10 m high riser of a circulating fluidized bed (CFB) system. The riser was operated at 4.0 to 10.0 m/s air velocity and 50 to 550 kg/m2s solids flux of spent fluid catalytic cracking (FCC) catalyst particles with 67 μm mean diameter and density of 1500 kg/m3. Data were analyzed using prepared FORTRAN 2008 code to get correlation integral followed by determination of correlation dimensions with respect to the hyperspherical radius and their profiles, plots of which were studied. It was found that correlation dimension profiles at the centre have single peak with higher values than the wall region profiles. Towards the wall, these profiles have double or multiple peaks showing bifractal or multifractal flow behaviors. As the velocity increases the wall region profiles become random and irregular. Further it was found that, as the height increases the correlation dimension profiles shift towards higher hyperspherical radius at the centre and towards lower hyperspherical radius in the wall region at r/R = 0.81. The established method of mapping correlation dimension profiles in this study forms a suitable tool for analysis of high-flux riser dynamics compared to other analyses approaches. However, further analysis is recommended to other gas-solid CFB riser of different dimensions operated at high-flux conditions using the established method.

Seasonal and diurnal variations in N2O concentrations and fluxes from three eutrophic rivers in Southeast China

This study was performed at three eutrophic rivers in Southeast China aiming to determine the magnitude and patterns of dissolved N2O concentrations and fluxes over a seasonal （in 2009） and diurnal （24 h） temporal scale.The results showed that N2O concentrations varied from 0.28 to 0.38 （mean 0.32±0.04）,0.29 to 0.46 （mean 0.37±0.07）,and 2.07 to 3.47 （mean 2.84±0.63） μg N-N2O L-1 in the Fengle,Hangbu and Nanfei rivers,respectively,in the diurnal study performed during the summer of 2008.The study found that mean N2O concentration and estimated N2O flux （67.89 ± 6.71 μg N-N2O m-2 h-1） measured from the Nanfei River with serious urban wastewater pollution was significantly higher than those from the Fengle and the Hangbu Rivers with agricultural runoff.In addition,the seasonal study during June and December of 2009 also showed that the mean N2O concentration （10.59±14.67 μg N-N2O L-1） and flux （236.87±449.74 μg N-N2O m-2 h-1） observed from the Nanfei River were significantly higher than those from the other two rivers.Our study demonstrated both N2O concentrations and fluxes exhibited seasonal and diurnal fluctuations.Over three consecutive days during the summer of 2008,N2O accumulation rates varied within the range of 3.91-7.21,2.76-15.71,and 3.23-30.03 μg N-N2O m-2 h-1 for the Fengle,Hangbu and Nanfei Rivers,respectively,and exponentially decreased with time.

CFD model simulation of bubble surface area flux in flotation column reactor in presence of minerals

Bubble surface area flux(S_b) is one of the main design parameter in flotation column that typically employed to describe the gas dispersion properties, and it has a strong correlation with the flotation rate constant. There is a limited information available in the literature regarding the effect of particle type,density, wettability and concentration on Sb. In this paper, computational fluid dynamics(CFD) simulations are performed to study the gas–liquid–solid three-phase flow dynamics in flotation column by employing the Eulerian–Eulerian formulation with k-e turbulence model. The model is developed by writing Fortran subroutine and incorporating then into the commercial CFD code AVL FIRE, v.2014.This paper studies the effects of superficial gas velocities and particle type, density, wettability and concentration on Sband bubble concentration in the flotation column. The model has been validated against published experimental data. It was found that the CFD model was able to predict, where the response variable as indicated by R-Square value of 0.98. These results suggest that the developed CFD model is reasonable to describe the flotation column reactor. From the CFD results, it is also found that Sb decreased with increasing solid concentration and hydrophobicity, but increased with increasing superficial gas velocity. For example, approximately 28% reduction in the surface area flux is observed when coal concentration is increased from 0 to 10%, by volume. While for the same solid concentration and gas flow rate, the bubble surface area flux is approximately increased by 7% in the presences of sphalerite.A possible explanation for this might be that increasing solid concentration and hydrophobicity promotes the bubble coalescence rate leading to the increase in bubble size. Also, it was found that the bubble concentration would decrease with addition of hydrophobic particle(i.e., coal). For instance, under the same operating conditions, approximately 23% reduction in the bubble concentration is predicted when the system was working with hydrophobic particles. The results presented are useful for understanding flow dynamics of three-phase system and provide a basis for further development of CFD model for flotation column.

Estimation of suspended sediment flux from acoustic Doppler current profiling along the Jinhae Bay entrance

A Nortek acoustic Doppler current profiler (NDP) was installed on a moving vessel to survey the entrance to the Jinhae Bay on August 22~23, 2001. The current velocity and acoustic backscattering signal were collected along two cross-sections; water samples were also collected during the measurement. The acoustic signals were normalized to compensate for the loss incurred by acoustic beam spreading in the seawater. The in situ calibration shows that a significant relationship is present between suspended sediment concentrations (SSC) and normalized acoustic signals. Two acoustic parameters have been determined to construct an acoustic-concentration model. Using this derived model, the SSC patterns along the surveyed cross-sections were obtained by the conversion of acoustic data. Using the current velocity and SSC data, the flux of suspended sediment was estimated. It indicates that the sediment transport into the bay through the entrance has an order of magnitude of 100 t per tidal cycle.

用非损伤微测技术研究肿瘤细胞的耐药性与其胞外H^+流变化的相关性

介绍了人乳腺癌细胞(药物敏感株MCF-7/S及耐药株MCF-7/R)在化疗药物阿霉素(adriamycin,ADR)处理下,细胞外pH和H+流动方向和速率的变化。为此,建立了一种基于非损伤微测技术(non-invasive micro-test technique,NMT)的药物抗性研究方法(drug resistance study method,DRSM),该方法可用于研究器官/组织/细胞外离子/分子活性与肿瘤细胞耐药性之间的相互关系。结果显示存在一个持续的并以固有振荡形式出现的胞外H+流现象。此外,耐药株净H+流在加ADR前趋近于零,而敏感株净H+流呈明显内流。敏感株和耐药株加ADR后净H+均呈外流,但耐药株的净H+外流速率要高于敏感株5倍。与净H+流动速率结果相一致的是胞外的pH也产生了相应的变化。因此,实验为胞外H+活性与肿瘤耐药性的相互关联提供了直接证据。

Magnetic Flux Controllers for Induction Heating Applications

Application of magnetic flux controllers/concentrators to induction heating coils can drastically improve the process efficiency and heat pattern control. Presentation includes: benefits provided by flux controllers, materials available for controllers, application techniques, computer assisted design of induction coils with concentrators, examples of applications. Depending on induction system design, magnetic flux controllers can concentrate heating in a specified area, change heat source distribution and shield a particular part zone or external area preventing unintended eddy current heating. Besides of the coil efficiency improvement and optimal power distribution, magnetic flux controllers reduce the coil current demand from a supplying circuitry thus strongly reducing losses in busswork, cables, transformers and inverter components. Improvement that can be achieved due to magnetic flux controllers is case dependable. 2D and 3D computer simulation allows the designer to predict accurately effect of controllers on the coil parameters and temperature distribution and optimize the whole electromagnetic system. Special attention in presentation is paid to new magnetodielectric materials optimized for induction heating conditions. These materials have high magnetic permeability and saturation flux density, excellent machinability, good chemical and temperature resistance. Concentrators from these materials can work in a wide range of frequencies and specific powers. Examples of magnetic flux controller application include surface hardening of shafts and gears, induction surface hardfacing and brazing.

电动汽车用新型模块化聚磁转子永磁电机设计及其对比分析

将轮辐型内置式转子和Halbach永磁阵列结合,并取消转子铁心加强筋,减小漏磁达到高聚磁同时兼顾凸极比,实现高转矩/功率密度和宽调速范围。在保证永磁体用量相同的情况下,建立新型高凸极比聚磁转子和V型转子两种电机模型,针对两者的分段转子拓扑,开展电磁性能对比分析,包括气隙磁密、凸极比、功率以及弱磁扩速能力等。同时,考虑到无转子铁心加强筋会导致转子分段存在结构强度问题,仿真验证新型高凸极比聚磁转子结构在最高转速6000 r/min时给予碳纤维护套保护下转子结构强度的可靠性;分析温度限制下新型高凸极比转子电机的功率输出。另外,对比两种不同电机结构的振动噪声情况。最后,研制一台16极/72槽新型高凸极比转子永磁电机样机,实验验证有限元分析结果的准确性。进一步说明了新型高凸极比转子永磁电机在转矩/功率密度和宽调速运行等方面的性能优势。

Quantum of the Magnetic Flux Characteristic forExperiments Performed on the Integer and Fractional Quantum Hall Effects

Experimentally the plateaus characteristic for the integer quantum Hall effect is obtained in vicinity of specific values of the magnetic induction. The paper demonstrates that the ratios of these induction values to carrier concentration in the planar crystalline samples approach systematically the quanta of the magnetic flux important for the behavior of superconductors. Moreover, the same quanta can be deduced from the Landau levels theory and their application in the magnetoresistance theory gives results being in accordance with experiments. The quanta of the magnetic flux similar to those for the integer quantum Hall effect can be obtained also for the fractional quantum Hall effect. This holds on condition the experimental ratio of the magnetic flux to carrier concentration is multiplied by the filling factor of the Landau level.

浅水湖泊冬季温室气体浓度与通量的变化特征及影响因素

内陆水体是大气二氧化碳(CO_(2))、甲烷(CH_(4))、氧化亚氮(N_(2)O)的重要自然排放源。为研究浅水湖泊温室气体溶存浓度及排放通量,以太湖流域上游浅水湖泊-长荡湖为例,在冬季(2022年1-2月)利用顶空平衡-气相色谱法对其表层水体温室气体溶存浓度及排放通量进行测定,综合采用方差分析、多元逐步回归分析等方法探究了长荡湖湖区及主要出入湖河口区温室气体溶存浓度与排放通量的空间分布特征及主要影响因素。结果表明:①长荡湖冬季CO_(2)、CH_(4)、N_(2)O平均溶存浓度分别为(40.49±14.18)μmol/L、(0.86±1.92)μmol/L和(18.43±8.44)nmol/L,平均排放通量分别为(49.99±69.49)μmol/(m^(2)·h)、(1.28±2.64)μmol/(m^(2)·h)和(12.01±14.37)nmol/(m^(2)·h)。②在空间分布上,湖区CO_(2)排放通量高于出入湖河口区,湖区CH_(4)、N_(2)O溶存浓度和排放通量均显著低于出入湖河口区。③CO_(2)排放主要受水温、电导率(EC)以及TN、TP和Chla浓度的影响,CH_(4)排放主要受pH、高锰酸盐指数(CODMn)、EC和DO浓度的影响,N_(2)O排放主要受pH以及DO、TN和TP浓度的影响。④长荡湖冬季CO_(2)、CH_(4)和N_(2)O累积排放通量分别为47.51、0.44和0.01 kg/hm^(2),结合水域面积估算得出温室气体排放总量为545.57 t(以CO_(2)当量计)。研究显示,长荡湖冬季温室气体排放呈现较明显的空间异质性,并受到不同区域水环境条件、外源营养输入及人类活动的共同影响。本研究强调了浅水湖泊冬季温室气体排放在内陆水体温室气体收支中的重要性,可为全球和区域湖泊温室气体排放精确估算提供重要支撑。

不均匀喷氨的NO_(x)通量获取方法和喷氨格栅阻力特性

不均匀喷氨的方法是根据喷氨格栅建立不同分区的NO_(x)通量,设计分区不同的喷氨量,而NO_(x)通量由两个参数即烟气流速和NO_(x)浓度决定,试验和数值模拟方法是获得这两个参数的重要手段。通过对比发现,数值模拟的边界条件在实际中难以确定,无法较好地模拟流速场,而试验是更优的一种方法。试验结果显示,不同负荷和煤种下,喷氨格栅截面的流速分布基本不变,某些区域始终高,某些区域始终低。同时得到NO_(x)浓度的不均匀系数相对于流速不均匀系数很小,且考虑喷氨截面到催化剂还有一段扩散距离,可以仅考虑主要影响因素即烟气流速对不均匀喷氨的喷氨量进行设计,该方法简单有效,在工程实际中应用效果较好。同时对喷氨支管的阻力特性进行了试验研究,利用多孔介质代替该区域可以极大简化数值模拟区域。

粤北水边河流域钙元素迁移的基岩制约作用

岩石风化是控制流域水体水化学特征的关键因素之一。为探索岩溶流域中不同基岩风化作用对地表水化学的影响,本文选择粤北典型岩溶流域(水边河)为研究对象,以水体[Ca^(2+)]变化和钙迁移机制为研究主线,通过连续5年的系统调查及采样分析,揭示不同岩性风化对干流水体中Ca^(2+)输送通量的贡献率和岩溶流域钙元素迁移的影响机理。结果表明:(1)不同基岩支流的水体[Ca^(2+)]差异明显,特别是在干季,碳酸盐岩支流水体的[Ca^(2+)]分别是花岗岩、砂岩和砾岩支流的3.8倍、4.7倍、14.9倍;(2)不同基岩支流汇入干流后,水化学变化具有滞后性,并且呈现季节性差异。其中,碳酸盐岩支流汇入后,干流水体的[Ca^(2+)]会滞后升高,而其他支流会稀释[Ca^(2+)],产生稀释作用,其效果在湿季比干季更明显;(3)通过统计分析得出,碳酸盐岩支流在流域土地面积占比为28%,而其对流域水体中[Ca^(2+)]的贡献率达到83%,说明岩溶流域中碳酸盐岩的风化的制约着钙元素的迁移过程;(4)2016-2020年间,水边河向连江输送的钙通量平均值为7.2×10^(4) t·a^(-1),其中,湿季平均输送量为5.8×10^(4) t·a^(-1),干季平均为1.4×10^(4) t·a^(-1);但岩溶水体中钙元素迁移不仅仅有水体溶解的Ca^(2+),还有沉积态钙迁移和水生生物的钙迁移过程,而农业活动及酸雨等过程可导致水体中[Ca^(2+)]发生明显变化,因此,农业活动和酸雨等对钙迁移的影响需要多加关注。

Measurements of atmospheric N_2O concentration and its emission fluxes from soil in China

Air samples in China were collected and determined for the concentration of N_2O. The production rates of N_2O from agricultural soils were measured with the chamber method.The results in- dicate that the background concentration of N_2O averages(308±5)×10^(-9)in 1989,which is close to that ob- tained at the other background stations abroad.However,at both urban and rural areas,atmospheric N_2O concentrations are higher.N_2O emission fluxes from several farmlands are different and dependent on the fac- tors of agricultural practice and climate.But their magnitudes are at the same order.Preliminary calculation shows that the released N_2O-N from agricultural sources(cultivated soil and N-fertilizers)amounts to 122 Gg/a in China in 1990.