Study on surface wave-induced mixing of transport flux residue under typhoon conditions

The transport flux residue of surface waves plays an important role in a variety of ocean phenomena,for example,the change in sea surface temperature(SST)and upper mixed layer profile that were studied in a series of recent papers.In the previous studies,its effect was discussed rigorously and fragmented based on numerical modeling.Here we propose a relatively comprehensive and simplified exposition of the wave transport flux residue,and focus on its influence under typhoon conditions with strong background current.An analogue Reynolds Number is presented for tentative comparison with wave-generated turbulence mixing,especially in the coastal area.Numerical results indicate that both overwhelming dynamical mixing processes can remarkably change the coastal environment,and should not be ignored consciously for further marine hazards assessment.

Effect of Kinetic Alfvén Waves on Electron Transport in an Ion-Scale Flux Rope

At the Earth＇s magnetopause, the electron transport due to kinetic Alfvén waves（KAWs） is investigated in an ion-scale flux rope by the Magnetospheric Multiscale mission. Clear electron dropout around 90° pitch angle is observed throughout the flux rope, where intense KAWs are identified. The KAWs can effectively trap electrons by the wave parallel electric field and the magnetic mirror force, allowing electrons to undergo Landau resonance and be transported into more field-aligned directions. The pitch angle range for the trapped electrons is estimated from the wave analysis, which is in good agreement with direct pitch angle measurements of the electron distributions. The newly formed beam-like electron distribution is unstable and excites whistler waves,as revealed in the observations. We suggest that KAWs could be responsible for the plasma depletion inside a flux rope by this transport process, and thus be responsible for the formation of a typical flux rope.

Simulation of Kelvin-Helmholtz Instability with Flux-Corrected Transport Method

第六顺序的精确阶段错误改正流动的运输数字算法被介绍，并且过去常模仿绝对温标 Helmholtz 不稳定性。模拟的线性生长率同意绝对温标 Helmholtz 不稳定性的线性理论。它显示这个模拟方法的有效性和精确性。方法也有不稳定性接口变丑的好捕获的能力。

Thermal stability and electrical transport properties of Ge/Sn-codoped single crystalline β-Zn4Sb3 prepared by the Sn-flux method

This study prepares a group of single crystalline β-Zn_4Sb_3 with Ge and Sn codoped by the Sn-flux method according to the nominal stoichiometric ratios of Zn_（4.4）Sb_3 Ge_xSn_3（x = 0–0.15）. The prepared samples possess a metallic luster surface with perfect appearance and large crystal sizes. The microscopic cracks or defects are invisible in the samples from the back-scattered electron image. Except for the heavily Ge-doped sample of x = 0.15, all the samples are single phase with space group R3c. The thermal analysis results show that the samples doped with Ge exhibit an excellent thermal stability.Compared with the polycrystalline Ge-substituted β-Zn_4Sb_3, the present single crystals have higher carrier mobility, and hence the electrical conductivity is improved, which reaches 7.48×10~4S·m^（-1） at room temperature for the x = 0.1 sample.The change of Ge and Sn contents does not improve the Seebeck coefficient significantly. Benefiting from the increased electrical conductivity, the sample with x = 0.075 gets the highest power factor of 1.45×10^（-3）W·m^（-1）·K^（-2） at 543 K.

Volume and heat transports and material fluxesin the East China Sea during April 1994

A modified inverse method is ed to compute the volume transport (VT), the heat transport (HT) andthe horizontal meterial fluxes in the East China Sea with data of CTD, T2, DOC, PCO, etc. Obtained in April1994. In April 1994 VT and HT through Section PN in the East China As are 30.6×106 m3/s and 2.42× 1015 Wrespectively, and the horizontal fluxes of T2, DOC and POC through Section PN are 65× 106,2. 2×106 and 0. 17×106 mol/s respectively. This means that the Percentages of fluxes of T2 , DOC and POC in total C flux are about96.5%, 3.3% and 0.2% respectively. VT and HT through betion Ss(near the Tokara Strait) are 26. 7×106m3/sand 2. 14× 1015 W respectively, which are about 87% and 88% of VT and HT through Section PN respectively. Thehorizontal flux of T2 through sation % is 61×106 mol/s, which is about 93. 8 % of the flux of T2 through SectionPN, i. e., its percentage is close to that of VT and HT of betions S5 and PN. The horizontal fluxes of DOC and POCthrough Section S5 are 2. 5× 106 and 0.08×106 mol/s respectively. The sum of the horizontal influx and outflux ofTop through the boundaries of Box-2 is about-2×106 mol/s (outflux), which is about 3% of the flux of T2 through Section PN. This value is the same order of magnitude of the vertical flux caused by the downwelling or theupwelling. Tins means that the horizontal flux of T2 must be considered, when the vertical flux of T2 is computed,and so are the other material vertical fluxes (DOC, etc. ). Finally, the vertical velocity component is computed with adiagnostic model.

Tracing surface seawater mixing and nutrient transport by^(222)Rn on the northern coast of Beibu Gulf,China

The transport and diffusion of substances in seawater are limited by the mixing motion of water bodies,while the main forms of mixing in offshore water bodies are advection and eddy diffusion.The eddy diffusion process of water indicates the possible transport direction of dissolved substances.However,the complex environment in the coastal zone makes it difficult to quantitatively assess the water diffusion process.^(222)Rn is a useful tool to trace the diffusion process of water bodies.However,studies on the^(222)Rn distribution and its behavior in the Beibu Gulf are scarce.In this study,the activity distribution characteristics of^(222)Rn in surface seawater of the Guangxi shelf area of the Beibu Gulf were measured.Based on the one-dimensional,steady-state model,the vorticity diffusion coefficient of^(222)Rn in the horizontal direction was calculated as(0.42−2.13)×10^(8) m^(2)/d,and the offshore fluxes of^(222)Rn under the influence of water mixing were calculated as 2.00×10^(12) Bq/d.Correspondingly,the horizontal transport fluxes of silicate,phosphate,nitrite and nitrate were 6.28×10^(−3)mol/(m^(2)·d),0.10×10^(−3)mol/(m^(2)·d),0.20×10^(−3)mol/(m^(2)·d)and 4.15×10^(−3)mol/(m^(2)·d),respectively.These results indicate that the study of eddy current diffusion in offshore marine water facilitates a deeper understanding of the water mixing process and nutrient transport and migration.

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.

Transport and transformation of nitrobenzene in Songhua River and calculation of flux and remnant based on quantification analysis

To evaluate the long-term environmental effect of the nitrobenzene precipitated into Songhua River caused by the explosion accident of CNPC Jilin Petrochemical Company, we have proved that three selected cross sections were all in a completely mixed state which was not affected by the neighborhood flow firstly. The research of the main flux of contaminants indicates that the nitrobenzene flux in all cross sections is less and less, and the attenuation trend is gradually slowing down. From the residual remnant of nitrobenzene in different segments calculated according to the related experimental data, we suppose that parts of nitrobenzene remnant are transferred by the bottom sludge adsorption and resolution. A general analysis model was set up from the one-dimensional counter-flow equation, and functions of atmosphere-water exchange process, deposit-water interaction, and river turbulent mixing and dissemination. The results of this quantification analysis are different from the real calculation, while the gross transformation trend is the same, which indicates that both analyses are based on reality and can reflect the transport and transformation of nitrobenzene actually.

High Efficiency LSM with High Flux Density for Transportation

A new linear synchronous motor (LSM) with permanent magnet (PM) is proposed to develop a linear motor for transportation with high efficiency. The LSM has very high air-gap flux density beyond the remanent magnetization of rare earth PM, which is generated by a special field structure with rare earth PM. Two PMs are arranged to form a triangle over each pole to concentrate the flux of PMs. The maximum value of air-gap flux density is limited to the magnetic saturated value in the core of field and armature, respectively, which is about 2T. The configuration is insusceptible to armature reaction because of large equivalent magnetic resistance in the flux path. The characteristics are analyzed using a two-dimensional finite element method (FEM) considering the core material. For high air-gap flux density and small armature reaction, the very high thrust density beyond the conventional maximum value of 100kN/m2 can be obtained. Using normal thrust density with small magneto-motive force (mmf) of armature, this LSM has efficiency and power factor that are as high as or higher than a rotational motor.

钛渣熔体结构及传输性质分子动力学模拟研究进展

高品位钛渣(TiO_(2)含量≥90%)的高效制备不仅是高品质钛产品生产的关键,而且已成为我国钛冶金行业发展的迫切需要。钛铁矿还原熔炼过程钛渣熔体传输性质的调控是实现高品位钛渣高效制备的关键。国内外学者采用分子动力学模拟的方法,开展钛渣熔体结构演变及传输性质的研究,取得了显著的进展,证实了分子动力学模拟的方法在钛渣熔体研究中的有效性。分子动力学模拟的方法在研究钛渣熔体结构和性质方面具有显著的优势,不但能考察钛渣熔体结构参数、传输性质及相关微观细节,而且不受试验条件(高温、高腐蚀性、高化学活性)的限制。通过分子动力学模拟能够获取钛渣熔体丰富的结构信息和重要的传输性质,避免了钛渣熔体结构及物理性质试验测试中存在的难题。最后,结合冶金熔体成分和结构的复杂性,总结存在的问题,对分子动力学模拟在熔体结构及传输性质研究中的应用进行了展望。

吐鲁番市高昌区不同固沙植物的防风固沙效益

为了解不同防风固沙林对风速、输沙通量和土壤蚀积程度的影响,以期为荒漠化地区植物选择和配置提供技术支持,以吐鲁番市高昌区恰特喀勒乡公相村为实验地,利用气象站、风速仪、集沙仪等监测不同高度下梭梭林、柽柳林以及梭梭-柽柳混交林的风速、地表粗糙度、输沙通量等指标,分析比较不同固沙林的风速廓线、风速增加率、地表蚀积量及风沙堆积物变化规律。结果表明:随着风速的增加,输沙通量逐渐增加,地表粗糙度和蚀积深度呈现降低趋势;不同固沙林不同高度(h)的风速增加率均表现为中层(50 cm<h≤100 cm)最大,低层(10 cm<h≤50 cm)最小,说明固沙植物对低层风速有显著降低作用,增强了中层风速;不同固沙林输沙通量随着高度增加逐渐减小;柽柳林、梭梭-柽柳混交林后出现堆积现象,梭梭林前后为侵蚀现象。梭梭林、柽柳林以及梭梭-柽柳混交林均降低了近地表风速,有效拦截了风沙流,改变了表层风沙堆积物物质组成,梭梭-柽柳混交林防风固沙效果较好。

长江口滨海湿地有机碳循环过程及影响因素研究进展

滨海湿地是“蓝碳生态系统”的重要组成部分。综述了长江口滨海湿地土壤有机碳时空分布及含量、碳汇速率、有机碳横向输入输出通量及量化方法、有机碳循环定量分析模型以及有机碳储量和组分对不同影响因素所做出的动态响应规律,发现在土壤有机碳水平空间分布上,崇西湿地>崇明东滩>九段沙>南汇潮滩;有机碳通量和浓度变化主要受到植物生物量和结构、水和土壤的理化性质、陆源输入和潮汐动力、间隙水交换以及人类活动和全球气候变化的影响。未来应加强长江口湿地土壤碳库和有机碳输运通量统一观测,准确量化各主要因素对有机碳的贡献,这对研究盐沼湿地的碳循环机理和碳汇评估具有重要意义。

CZTS基单晶材料研究进展和展望

Ⅰ_(2)-Ⅱ-Ⅳ-Ⅵ_(4)型半导体铜锌锡硫(CZTS)在成本、组成元素丰度、毒性和稳定性等方面具有突出优势,被认为是一种很有前途的太阳能吸收材料,应用于绿色和经济的光伏领域。尽管Cu_(2)ZnSn(S,Se)_(4)拥有与黄铜矿相似的晶体结构和光电性能,但其转换效率却远远低于Cu(In,Ga)Se_(2)(23.5%)。传统研究多数集中在多晶薄膜材料和器件的光电性能,导致材料关键缺陷态甄别及其能带调控规律尚不清晰,成为限制CZTS基光电器件性能的瓶颈。本文综述了CZTS基单晶材料,详细介绍了其晶体结构和物理性质,概述了移动加热器法、碘输运法和熔盐法制备高质量单晶的工艺,多型纳米晶库的研究,以及天然锌黄锡矿的物性研究。根据制备的CZTS基单晶材料讨论了其光学和电学性能。最后总结了CZTS基单晶材料在半导体器件的应用及目前存在的问题,为提高Ⅰ_(2)-Ⅱ-Ⅳ-Ⅵ_(4)型半导体材料器件的性能提供可能的发展方向。

基于激光雷达观测的青岛市暖季臭氧污染垂直分布特征

为探究暖季臭氧(O_(3))污染垂直分布特征及其影响因素,利用差分吸收臭氧激光雷达和相干多普勒测风激光雷达等对青岛市沿海地区2023年6−9月大气边界层2000 m以内O_(3)浓度和边界层风场开展长期连续观测,并基于O_(3)输送通量垂直分布揭示可能的污染来源。结果表明:①观测期间共发生O_(3)污染日24 d,O_(3)-8 h浓度(O_(3)日最大8 h平均浓度)平均值为(183±24)μg/m^(3);清洁日共98 d,O_(3)-8 h浓度平均值为(118±30)μg/m^(3)。O_(3)污染过程多与升温过程密切相关,在较强太阳辐射和低相对湿度条件下更容易发生O_(3)污染。②垂直方向上O_(3)主要分布在1000 m以下。清洁日各高度层日间和夜间O_(3)浓度变幅较小,污染日各高度层O_(3)浓度单峰型日变化特征显著,且日变化特征随高度升高而逐渐减弱。清洁日日间、夜间以及污染日夜间O_(3)浓度垂直廓线均存在峰值,峰值浓度分别为(115±3)(112±2)和(130±3)μg/m^(3),峰值高度范围为400~650 m,可能与近地面NO滴定效应等消耗O_(3)有关,也可能是残留层储存的日间高浓度O_(3)或残留层O_(3)水平输送导致,但污染日日间垂直廓线呈随高度上升而O_(3)浓度逐步下降的特征,表明近地面前体物光化学生成是O_(3)污染的主要来源。③当西北风和西南风更替、低空暖平流和较强下沉气流等大气条件发生时,有利于污染物累积和O_(3)生成,从而引发O_(3)污染。清洁日低空(近地面至600 m高度)受较为清洁的海洋气流影响,污染日受内陆方向气流影响。④污染日凌晨至上午受来自偏西、西南或西北上风向O_(3)水平输送影响,高空O_(3)伴随下沉气流向下混合,与本地排放前体物在日间高温、强太阳辐射等气象条件下生成的O_(3)叠加,从而加剧地面O_(3)污染,午后高浓度O_(3)在较高水平风速影响下也可能向下风向地区输送。研究显示,O_(3)污染防治不仅要做好本地前体物的精准管控,还要加强区域联防联控,从而实现空气质量持续改善。

长江口南槽悬沙纵向和横向输运过程与机制研究

河口悬沙输运对于最大浑浊带形成发育、地貌演变、港口航道安全、水质以及生态系统健康至关重要。本文基于2017年洪季长江口南槽拦门沙海域4站位同步观测的沉积动力数据,采用Scully和Sommerfield改进的通量机制分解法来获取垂向各层平流通量和潮泵通量及累积动态变化,以确定平流和潮汐泵送对悬沙净通量的相对贡献,探讨纵向和横向的水沙输运时空格局和动力机制,弥补了传统通量机制分解法仅限计算时空平均值的缺陷。研究发现:(1)洪季长江口南槽拦门沙海域大潮期间存在横向余环流,小潮期间出现表层向海、底层向陆的纵向余环流;(2)平流和潮泵作用是影响净输运的关键因素,南槽拦门沙海域由平流作用主导、悬沙向海净输运,横向上向西南边滩输运,为南汇边滩围垦区向海淤长提供物源,且靠近主槽区域横向悬沙通量对沉积过程的贡献与纵向通量相当;(3)潮泵输运在河口滞流点和拦门沙海域均较显著,泵送的大小和方向与径潮流相互作用和底床物源有关,纵向上由大潮期间向陆泵送占优转为小潮期间的向海净输运占优。综上,南槽拦门沙海域近底层悬沙呈现由浅滩向主槽辐聚的格局,浅滩区域的近底层悬沙净输运受潮泵作用控制,且对整个水柱悬沙输运贡献显著,可能是拦门沙形成和最大浑浊带发育的重要机制。

土壤和地下水中重金属污染物迁移模型:以某有色金属冶炼厂为例

冶炼厂表层土壤重金属污染严重。由于数据采集和计算量的限制,大多数数值模拟将土壤和地下水分开,这与实际情况不符。本文以某冶炼厂为研究对象,将土壤和地下水视为一个整体系统,建立了土壤-地下水反应性溶质迁移三维耦合数值模型,以定量表征重金属在土壤和地下水中的迁移规律。模型采用反应系数(λ)和滞留系数(R)来描述重金属的释放和吸附能力。模型结果与现场实际污染分布一致,表明土壤-地下水修复技术对严重污染土壤和局部污染地下水均有良好的修复效果。所构建的土壤-地下水反应性溶质迁移三维耦合模型很好地描述和预测研究地点重金属的分布和迁移扩散行为。

Sand flux estimation during a sand-dust storm at Tazhong area of Taklimakan Desert, China

In this paper, the sand transport during a sand-dust storm in the Tazhong area of the central Taklimakan Desert from 11：29 to 23：56 on July 19, 2008 was observed and measured in real time. The sand flux at Tazhong was estimated using sand transport empirical formulas. The critical friction velocity at Tazhong was 0.24 m/s and the functional relation between the wind speed and sediment discharge at the height of 2 m was established. It was also found that the calculated values by Lettau＇s sediment discharge formula were close to those of the instrument measurements. The horizontal sand flux and the vertical sand flux during this sand-dust storm at Tazhong were respectively 258.67×10-4 kg/（m·s） and 40.07×10-7 kg/（m2·s）.

Tb(III) Transport in Dispersion Supported Liquid Membrane System with D2EHPA as Carrier in Kerosene

The transport of Tb（III） in dispersion supported liquid membrane（DSLM） with polyvinylidene fluoride membrane（PVDF） as the support and dispersion solution including HCl solution as the stripping solution and di（2-ethylhexyl） phosphoric acid（D2EHPA） dissolved in kerosene as the membrane solution, has been studied. The effects of pH value, initial concentration of Tb（III） and different ionic strength in the feed phase, volume ratio of membrane solution to stripping solution, concentration of HCl solution, concentration of carrier, different stripping agents in the dispersion phase on the transport of Tb（III） have also been investigated, respectively. As a result, the optimum transport conditions of Tb（III） were obtained, i.e., the concentration of HCl solution was 4.0 mol/L, the concentration of D2EHPA was 0.16 mol/L, the volume ratio of membrane solution to stripping solution was 30：30 in the dispersion phase and pH value was 4.5 in the feed phase. Ionic strength had no obvious effect on the transport of Tb（III）. Under the optimum conditions, the transport percentage of Tb（III） was up to 96.1% in a transport time of 35 min when the initial concentration of Tb（IIl） was 1.0× 10 -4 mol/L. The diffusion coefficient of Tb（III） in the membrane and the thickness of diffusion layer between feed phase and membrane phase were obtained and the values were 1.82×10 -8 m2/s and 5.61 um, respectively. The calculated results were in good agreement with the literature data.

STUDY OF WATER-TRANSPORT THROUGH SOME MAIN STRAITS IN THE EAST CHINA SEA AND SOUTH CHINA SEA

OCCAM global ocean model results were applied to calculate the monthly water transport through 7 straits around the East China Sea (ECS) and the South China Sea (SCS). Analysis of the features of velocity profiles and their variations in the Togara Strait, Luzon Strait and Eastern Taiwan Strait showed that: 1) the velocity profiles had striped pattern in the Eastern Taiwan Strait, where monthly flux varied from 22.4 to 28.1 Sv and annual mean was about 25.8 Sv; 2) the profiles of velocity in the Togara Strait were characterized by core structure, and monthly flux varied from 23.3 to 31.4 Sv, with annual mean of about 27.9 Sv; 3) water flowed from the SCS to the ECS in the Taiwan Strait, with maximum flux of 3.1 Sv in July and minimum of 0.9 Sv in November; 4) the flux in the Tsushima Strait varied by only about 0.4 Sv by season and its annual mean was about 2.3 Sv; 5) Kuroshio water flowed into the SCS in the Luzon Strait throughout the year and the velocity profiles were characterized by multi core structure. The flux in the Luzon Strait was minimum in June (about 2.4 Sv) and maximum in February (about 9.0 Sv), and its annual mean was 4.8 Sv; 6) the monthly flux in the Mindoro Strait was maximum in December (3.0 Sv) and minimum in June (only 0.1 Sv), and its annual mean was 1.3 Sv; 7) Karimata Strait water flowed into the SCS from May to August, with maximum inflow flux of about 0.75 Sv in June and flowed out from September to April at maximum outflow flux of 3.9 Sv in January. The annual mean flux was about 1.35 Sv.

Near-surface sand-dust horizontal flux in Tazhong-the hinterland of the Taklimakan Desert

Tazhong is the hinterland and a sandstorm high-frequency area of the Taklimakan Desert. However, little is known about the detailed time-series of aeolian sand transport in this area. An experiment to study the sand-dust horizontal flux of near-surface was carried out in Tazhong from January to December 2009. By measur- ing the sand-dust horizontal flux throughout sixteen sand-dust weather processes with a 200-cm tall Big Spring Number Eight （BSNE） sampler tower, we quantitatively analyzed the vertical variation of the sand-dust horizontal flux. And the total sand-dust horizontal flux of different time-series that passed through a section of 100 cm in width and 200 cm in height was estimated combining the data of saltation movement continuously recorded by piezo- electric saltation sensors （Sensit）. The results indicated that, in the surface layer ranging from 0-200 cm, the inten- sity of sand-dust horizontal flux decreased with the increase of the height, and the physical quantities obeyed power function well. The total sand-dust horizontal flux of the sixteen sand-dust weather processes that passed through a section of 100 cm in width and 200 cm in height was about 2,144.9 kg, the maximum of one sand-dust weather event was about 396.3 kg, and the annual total sand-dust horizontal flux was about 3,903.2 kg. The high levels of aeolian sand transport occurred during daytime, especially from 13：00 to 16：00 in the afternoon. We try to develop a new method for estimation of the detailed time-series of aeolian sand transport.