A Three-dimensional Wave Activity Flux of Inertia–Gravity Waves and Its Application to a Rainstorm Event

A three-dimensional transformed Eulerian-mean(3D TEM) equation under a non-hydrostatic and non-geostrophic assumption is deduced in this study. The vertical component of the 3D wave activity flux deduced here is the primary difference from previous studies, which is suitable to mesoscale systems. Using the 3D TEM equation, the energy propagation of the inertia–gravity waves and how the generation and dissipation of the inertia–gravity waves drive the mean flow can be examined. During the mature stage of a heavy precipitation event, the maximum of the Eliassen–Palm(EP) flux divergence is primarily concentrated at the height of 10–14 km, where the energy of the inertia–gravity waves propagates forward(eastward) and upward. Examining the contribution of each term of the 3D TEM equation shows that the EP flux divergence is the primary contributor to the mean flow tendency. The EP flux divergence decelerates the zonal wind above and below the high-level jet at the height of 10 km and 15 km, and accelerates the high-level jet at the height of 12–14 km. This structure enhances the vertical wind shear of the environment and promotes the development of the rainstorm.

Reconstruction of heat flux profile on the HL-2A divertor plate with a three-dimensional analysis model

A three-dimensional analysis model based on the finite element method （FEM） is developed, which can derive the evolution and distribution characteristics of heat flux deposited on the divertor plate from the surface temperature measured by infrared thermography diagnostics. The numerical simulations of surface heating due to localized power bursts and the power deposition calculations demonstrate that this analysis can provide accurate results and useful information about localized hot spots compared with the normal one- and two-dimensional calculations. In this paper, the details of this three- dimensional analysis are presented, and some results in ohmic heating and electron cyclotron resonant heating （ECRH） discharge on HL-2A are given.

Diagnosis of the Medium-Range Variation of the Subtropical High over the Western Pacific during a Meiyu Process by Three-Dimensional E-P Flux

In this paper, using the daily grid data (2.5 × 2.5) of the ECMWF / WMO, we have computed respectively the three-dimensional wave activity flux in the stages of pre-onset, prevailing and post ending of Meiyu from 1 to 31 July 1982. The potential vorticity field is taken as the physical quantity relating the wave activity flux to the variation of the subtropical high over the Western Pacific. It is found that the three-dimensional wave activity flux is a powerful means for diagnosis of the variation of the subtropical high over the Western Pacific: The region of the subtropical high is just the confluence area of wave energy, whose changes in intensity and range decide the variation of the subtropical high. The confluence of wave energy comes from the monsoon flow in low latitudes, the Meiyu rain belts in middle latitudes and the heating fields on the eastern side of the Qinghai-Xizang Plateau. The relation between these sources and the subtropical high displays the self-adjusting mechanism among members of East-Asia summer monsoon.

全球500kPa角动量与EP通量的季节变化

利用ＥＣＭＷＦ提供的９ａ（１９８Ｏ－１９８８）资料，从定性和定量角度分析５００ｈＰａ全球东西风带的角动量和ＥＰ通量的季节过渡。结果发现：不仅角动量存在明显的季节性急变，而且反映波活动的ＥＰ通量也存在相应的季节性急变。另外，季节性急变的发生时间在东西风带亦有所不同。

一种用于EPS系统的永磁同步电机弱磁控制的改进方法

针对目前驾驶员在快速转动方向盘时感到沉重的缺点,分析了用于电动助力转向系统的永磁同步电机弱磁控制动态性能差的原因。提出了一种基于前馈和模糊PI的综合弱磁控制方法。该方法通过弱磁控制实现了从直轴电流调节到正交轴电流调节的平滑过渡,并拓宽了前馈控制的弱磁深度。最后,通过仿真分析和硬件在环测试验证了该方法的有效性。

汉江流域盛夏暴雨与天气尺度瞬变波EP通量的可能联系

利用1980—2015年ERA-5全球再分析资料,对汉中地区典型暴雨发生前纬向风场变化及天气尺度瞬变波活动(Eliassen-Palm通量特征)进行分析。结果表明:瞬变波Eliassen-Palm(EP)通量特征分析为汉江流域暴雨潜势预报提供一个有利的参考指标;暴雨发生前,33°N附近200 h Pa有纬向风减速中心,对应200 hPa为EP通量辐散区,这种垂直分布模型是暴雨前期的有利形势,随着纬向风减速趋势加快,EP通量辐散区扩展并加强,有利于暴雨的发生;与8月相比,7月暴雨强度更强,暴雨范围更广,纬向风变化更明显,200 hPa的EP通量辐散更强。若简单地将盛夏暴雨整体进行研究,会影响对不同月份瞬变波活动及大气环流变化趋势的诊断,造成诊断偏差且难以准确反映瞬变波与暴雨的联系。因此在讨论盛夏季天气尺度瞬变波与对流层环流的相互作用时,应按月份讨论。

EPS用PMSM弱磁控制方法与实现

针对汽车在紧急避障等工况下,驾驶员快速转方向盘时手感沉重问题,根据电动助力转向系统用永磁同步电机调速,设计超前角弱磁控制方法。电机转速在基速以下时采用id=0控制,电机在高转速下用弱磁控制,并用Matlab/Simulink进行了系统仿真验证。仿真结果表明,本弱磁控制方法能够有效地减少方向盘转矩,提高电机转速。

基于弱磁控制的EPS模式切换中转矩波动的抑制

针对电动助力转向系统(EPS)用永磁同步电机在i_d=0控制与弱磁控制相互切换的过程中转矩波动对系统性能的影响,设计了负载转矩观测器,对速度环中的弱磁控制模式输出的转矩进行补偿;并在两种模式切换时加入了转矩平滑切换模块,解决了切换过程中由于转矩突变带来的操纵转矩波动问题。仿真与试验结果表明,通过负载转矩观测器进行负载前馈补偿,使系统对负载扰动有很强的鲁棒性;转矩平滑切换模块对工作模式切换过程中产生的操纵转矩波动有很好的抑制作用,改善了驾驶员操纵沉重和转矩波动等不良手感。

Developing a 3D-FEM Model for Electromagnetic Analysis of an Axial Flux Permanent Magnet Machine

Recently, many optimal designs for axial flux permanent magnet (AFPM) motors were performed based on finite- element (FE) analysis. Most of the models are based on reduction of 3D problem to 2D problem which is not accurate for design aspects. This paper describes an accurate electromagnetic analysis of a surface mounted, 28 pole AFPM with concentrated stator winding. The AFPM is modeled with three-dimensional finite-element method. This model in-cludes all geometrical and physical characteristics of the machine components. Using this accurate modeling makes it possible to obtain demanded signals for a very high precision analysis. Magnetic flux density, back-EMF, magnetic axial force and cogging torque of the motor are simulated using FLUX-3D V10.3.2. Meanwhile, the model is paramet-ric and can be used for design process and sensitivity analysis.

COATS:Comprehensive observation on the atmospheric boundary layer three-dimensional structure during haze pollution in the North China Plain

The North China Plain(NCP)is troubled by severe haze pollution and the evolution of haze pollution is closely related to the atmospheric boundary layer(ABL).However,experimental and theoretical studies on the physical-chemical processes of the ABL in the NCP are lacking,with many scientific problems to be addressed.To solve these problems,the Comprehensive Observation on the Atmospheric boundary layer Three-dimensional Structure(COATS)during haze pollution was carried out in the NCP from 2016 to 2020.The COATS experiment adopted a"point-line-surface"spatial layout,obtaining both spatial-temporal profiles of the meteorological and environmental elements in the ABL and the turbulent transport data of fine particulate matter(PM_(2.5))in winter and summer.The research achievements are as follows.The spatial-temporal distribution characteristics of the ABL structure and PM_(2.5)concentrations in NCP were determined.The typical thermal structure of persistent heavy haze events and the pollutant removal mechanism by low-level jets were revealed.It was determined that the spatial structure of the ABL adjusted by the Taihang Mountains is responsible for the heterogeneous distribution of haze pollution in the NCP,and that mountain-induced vertical circulations can promote the formation of elevated pollution layers.The restraints of the atmospheric internal boundaries on horizontal diffusion of pollutants were emphasized.The contribution of the ABL to haze pollution in winter and summer was qualitatively compared and quantitatively estimated.The turbulent transport nature behind the relationship between the atmospheric boundary layer height(ABLH)and surface PM_(2.5)concentrations was analyzed.The concept of"aerosol accumulation layer"was defined,and the applicability of the material method in determining ABLH was clarified.A measurement system for obtaining the turbulent flux of PM_(2.5)concentrations was developed,and the turbulence characteristics of PM_(2.5)concentrations were demonstrated.The COATS experiment is of great theoretical significance for thoroughly understanding the physical mechanisms of the ABL during haze pollution and filling the knowledge gap on the impacts of the ABL three-dimensional structure on haze pollution.The results of this study are conducive to the improvement and development of ABL parameterization schemes and serve as a scientific basis for formulating regional pollution prevention and control measures.

胞外聚合物对膜生物反应器运行性能的影响

膜生物反应器处理污水过程中,依据胞外聚合物(EPS)、蛋白质、多糖、粘度等参数随时间的变化趋势以及对膜通量的影响,求出上述参数及蛋白质/多糖的比值与膜通量间的相关系数分别为0.28、0.57、0.38、0.14、0.70。结果表明:蛋白质/多糖的比值与膜通量的衰减速度两者相关系数最大。

投加粉末活性炭对MBR运行性能的影响

试验研究比较了在相同的进水和运行条件下,反应器1(投加粉末活性炭,投加量为12.3 g,使其质量浓度达到1100 mg/L)和反应器2(未投加粉末活性炭)的膜透水性及对污染物的去除效果,并分析了粉末活性炭可以提高膜过滤性能的相关机理。试验结果表明:反应器1的膜通量衰减速率明显小于反应器2;投加粉末活性炭改变了混合液的性质,也大大降低了混合液中胞外聚合物和微细胶体的含量,从而减缓了膜通量的下降速度,可以使系统长时间地以相对高的膜通量运行。

平流层爆发性增温期间行星波的活动

利用逐日的NCEP再分析资料分析了1978-2004年期间发生的18次强爆发性增温时平流层中下层行星波1波和2波的异常以及极涡崩溃的形式。分析表明，爆发性增温前期1波都异常增幅，波振幅达到峰值之后的一段时间内发生爆发性增温，然而在增温过程中行星波2波的变化却有明显不同，可分为三种情况：（1）在增温前期，行星波2波很弱；在增温期间，行星波2波异常发展，伴随着极涡崩溃的形式是由偏心型向偶极型过渡。（2）在增温前期，行星波2波较强；在增温期间，行星波2波明显减弱，极涡的变化形式是远离极地，在极地外围活动，但不发生分裂。（3）在增温前期，行星波2波不太强；在增温期间，行星波2波有所发展，但始终强不过1波，极涡的变化是先偏离极地，然后发生不对称的变形。作者还计算和分析了EP通量及其散度，利用波流相互作用理论对这三种行星波的异常变化及其与爆发性增温的关系进行解释。

北半球准定常行星波气候平均态的资料分析和数值模拟

利用NCEP/NCAR再分析资料和大气环流模式(CCSR/NIES AGCM Ver 5.6),对北半球准定常行星波的气候平均态分布进行分析和模拟。再分析资料分析的结果表明:北半球冬季,准定常行星波沿两支波导向上传播,其中一支在对流层上层转向中低纬度传播,另外一支折向高纬度,通过极地波导上传到平流层。其中,1波和2波可以上传到平流层,因而其振幅分布除在中低纬的对流层上层出现一个次大值外,在高纬度平流层中上层会出现一个最大值,3波则主要限制在对流层,其振幅分布除在副热带对流层上层出现一个次大值外,最大值出现在中纬度对流层上层。北半球夏季,整个平流层为东风环流,极地波导不存在,行星波不能上传到平流层,在对流层活动也较弱,1波、2波、3波的传播情况大致相似,表现为在对流层上层由中纬度向赤道地区的传播。相应的振幅分布是,对1波和2波而言,最大值出现在中低纬对流层顶附近,同时在中高纬对流层上层出现一个次大值,而3波的振幅分布正好相反,最大值出现在中高纬对流层上层,次大值则在中低纬对流层顶附近。利用大气环流模式进行的数值模拟表明,模式可以比较好地模拟冬夏季准定常行星波的传播路径,但模拟的北半球冬季沿极地波导向平流层的传播明显偏弱,其结果是对1波、2波而言,高纬度平流层中上层的振幅最大值明显小于再分析资料的数值。文中还讨论了数值模拟与资料分析中行星波的差异可能对大气环流模拟的影响。

生物信息学用于代谢网络研究的进展与展望

如何分析基因测序和高通量分析方法所获得的海量数据和信息 ,及由此而得到的复杂生物网络 ,是生物信息学研究者所面临的重要任务 .本文综述了基于基因组的大规模代谢网络重建和分析的进展 ,论述了利用生物信息学方法分析代谢网络结构的主要方法和结果 ;比较了现阶段两种最常用的代谢途径分析方法 ,即基元模式和极端途径的差异 ;列举了这两种方法在代谢网络结构和功能分析、工程菌设计等多方面的重要应用 ;指出了现阶段在途径分析领域存在的问题和应对的策略 .

生物膜厚度对膜曝气生物膜反应器硝化性能的影响

在设定的膜内压力下(2 k Pa)启动并运行膜曝气生物膜反应器(MABR),对生物膜生长过程中的硝化性能及生物膜组成变化进行了分析。实验结果表明,在生物膜厚度增长到(293.3±5.8)μm的过程中,生物膜内的总氧通量先增加后减少,最高可达21.3 g O2?m?2?d?1,证实了生物膜的存在可增强MABR的氧传质能力。在生物膜厚度增长的过程中,氨氮表面去除负荷也是先增加后减少,最高可达4.91 g N?m?2?d?1,表明在MABR硝化过程中存在最佳的生物膜厚度,根据所研究最佳生物膜厚度为(119.0±3.0)μm,此时MABR具有最高的氧通量和氨氮表面去除负荷,硝化性能最好。生物膜内胞外聚合物(EPS)成分分析结果表明,随着生物膜厚度的增加,生物膜内层紧密型EPS的含量增加,导致氧传质阻力增加,这是生物膜内氧通量及氨氮去除负荷随生物膜厚度先增加后下降的内在原因。

2002/2003年与2003/2004年冬季爆发性增温期间的动力特征

利用ECMWF提供的60层气象场资料诊断分析了2002/2003和2003/2004年两个冬季的爆发性增温(stratospheric sudden warming,SSW)过程,比较了两次SSW期间高纬温度和纬向风的差异,计算了SSW期间的EP通量和剩余环流。结果表明:2003/2004年增温持续时间长、强度大,而2002/2003年则发生了波动;增温都是从平流层上层开始向下传播,但是2003/2004年高层极涡崩溃后迅速恢复,低层极涡恢复得慢,2002/2003年极涡在高层和低层都是缓慢恢复;SSW期间行星波活动较多,2003/2004年极地EP通量的辐合引起东风长时间持续从而阻止了行星波再次上传,而2002/2003年行星波则发生多次上传;2002/2003年SSW发生时高纬地区为下沉气流,没有形成环流圈,增温后形成逆时针的环流圈比2003/2004年偏低。

Investigation of bubbles escape behavior from low basicity mold flux for high-Mn high-Al steels using 3D X-ray microscope

During the continuous casting process of high-Mn high-Al steels,various types of gases such as Ar need to escape through the top of the mold.In which,the behavior of bubbles traversing the liquid slag serves as a restrictive link,closely associated with viscosity and the thickness of liquid slag.In contrast to two-dimensional surface observation,three-dimensional(3D)analysis method can offer a more intuitive,accurate,and comprehensive information.Therefore,this study employs a 3D X-ray microscope(3D-XRM)to obtained spatial distribution and 3D morphological characteristics of residual bubbles in mold flux under different basicity of liquid slag,different temperatures,and different holding times.The results indicate that as basicity of slag increases from 0.52 to 1.03,temperature increases from 1423 to 1573 K,the viscosity of slag decreases,the floating rate of bubbles increases.In addition,when holding time increases from 10 to 30 s,the bubbles floating distance increases,and the volume fraction and average equivalent sphere diameter of the bubbles solidified in the mold flux gradually decreases.In one word,increasing the basicity,temperature,and holding time leading to an increase in the removal rate of bubbles especially for the large.These findings of bubbles escape behavior provide valuable insights into optimizing low basicity mold flux for high-Mn high-Al steels.

瞬变波动力强迫对初夏至盛夏东亚高空西风急流变化的影响

利用NCEP/NCAR逐日再分析资料,探讨了瞬变波动力强迫作用对初夏至盛夏急流北跳和急流中心西移的影响。结果表明,瞬变波的动力强迫作用有利于急流北跳的发生,但不利于急流中心西移的发生。通过分析年际尺度上初夏至盛夏急流变化的早晚与瞬变波异常的关系发现,对于急流北跳发生的早晚,瞬变波异常的动力强迫作用为正反馈作用;对于中心西移发生的早晚,瞬变波异常的动力强迫作用则为负反馈作用。可见,瞬变波的动力强迫作用对初夏至盛夏急流变化及其发生早晚具有重要影响,但对急流北跳和急流中心西移的作用显著不同。

热带太平洋海温异常对北极海冰的可能影响

本文利用1950-2015年间Hadley环流中心海冰和海温资料及NCEP/NCAR再分析资料,研究了热带太平洋海温异常对北极海冰的可能影响,并从大气环流和净表面热通量两个角度探讨了可能的物理机制。结果表明,在ENSO事件发展年的夏、秋季节,EP型与CP型El Ni1o事件与北极海冰异常的联系无明显信号。而La Ni1a事件期间北极海冰出现显著异常,并且EP型与CP型La Ni1a之间存在明显差异。EP型La Ni1a发生时,北极地区巴伦支海、喀拉海关键区海冰异常减少,CP型La Ni1a事件则对应着东西伯利亚海、楚科奇海地区海冰异常增加。在EP型La Ni1a发展年的夏、秋季节,热带太平洋海温异常通过遥相关波列,使得巴伦支海、喀拉海海平面气压为负异常并与中纬度气压正异常共同构成类似AO正位相的结构,形成的风场异常有利于北大西洋暖水的输入,同时造成暖平流,偏高的水汽含量进一步加强了净表面热通量收入,使得巴伦支海、喀拉海海冰异常减少。而在CP型La Ni1a发展年的夏季,东西伯利亚海、楚科奇海关键区受其东侧气旋式环流的影响,以异常北风分量占主导,将海冰从极点附近由北向南输送到关键区,海冰异常增加,而净表面热通量的作用较小。