A theoretical model for mid-and low-latitude ionospheric electric fields in realistic geomagnetic fields

The geomagnetic fields, which play important roles in the ionospheric dynamo, can greatly affect the global distribution of ionospheric electric fields, currents and other ionospheric electrodynamics phenomena. In the study of ionospheric electrodynamics phenomena, such as the longitudinal variations of ionospheric electric fields, the non-dipolar component of the geomagnetic fields must be taken into account. In this paper, we deduce a theoretical electric field model for ionospheric dynamo at mid- and low-latitude which adopt a modified magnetic apex coordinates system. In the new electric field model, the geomagnetic fields can be calculated from either the IGRF model or the dipole field model, and the neutral winds and conductivities are calculated based on empirical models. Then the dynamo equation for the electric potential is finally solved in terms of the line-by-line iteration method, and the ionospheric electric fields and currents are derived from the calculated potential. Our model can reproduce the main features of the ionospheric electrodynamics processes, so it will be a useful tool for the investigation of the upper atmosphere and ionosphere.     

Sea surface temperature records of core ZY2 from the central mud area in the South Yellow Sea during last 6200 years and related effect of the Yellow Sea Warm Current

Sea surface temperature (SST) records in the South Yellow Sea during the last 6200 years are reconstructed by the unsaturation index of long-chain alkenones (K 37 U ’) in sediment core ZY2 from the central mud area.The SST records varied between 14.1 and 16.5°C (15.6°C on average),with 3 phases:(1) A high SST phase at 6.2-5.9 cal ka BP;(2) A low and intensely fluctuating SST phase at 5.9-2.3 cal ka BP;and (3) A high and stable SST phase since 2.3 cal ka BP.Variation of the SST records is similar to intensity of the Kuroshio Current (KC),and corresponds well in time to global cold climate events.However,the amplitude of the SST response to cooling events was significantly different in different phases.The SST response to global cooling event was weak while the KC was strong;and the SST response was strong while the KC was weak.The difference in amplitude of the SST response is possibly caused by the modulation effect of the Yellow Sea Warm Current which acts as a shelf branch of the KC and a compensating current induced by the East Asia winter monsoon.The warm waters brought by the Yellow Sea Warm Current cushion the SST decrease induced by climate cooling,and both the Kuroshio and East Asian winter monsoon play important roles in the modulation mechanism.The SST records display a periodicity of 1482 years.The same period was found in the KC records,indicating that variation of the SST records in the central South Yellow Sea is strongly affected by KC intensity.The same period was also found in Greenland ice cores and North Atlantic and Arabian Sea sediment cores,showing a regional response of marine environmental variability in the East China Seas to that in the global oceans.     

Development of a middle and low latitude theoretical ionospheric model and an observation system data assimilation experiment

On the basis of previous work, we develop a middle and low latitude theoretical ionospheric model in this paper, named Theoretical Ionospheric Model of the Earth in the Institute of Geology and Geophysics, Chinese Academy of Sciences （TIME-IGGCAS）. TIME-IGGCAS solves the equations of mass continuity, motion and energy of electron and ions self-consistently and uses an eccentric dipole field approximation to the Earth＇s magnetic field. We combine the Eulerian and Lagrangian approaches in the model and take account of the plasma ExB drift velocity. Calculation results reveal that the model is steady and credible and can reproduce most large-scale features of ionosphere. By using TIME-IGGCAS, we carried out an observation system data assimilation experiment. Assimilation results show that the ExB drift velocity can be accurately estimated by ingesting the observed foF2 and hmF2 into the model applying nonlinear least-square fit method. We suggest that this work is of great significance in the development of ionospheric data assimilation model to give better nowcast and forecast of ionosphere.     

旋转液膜反应器倾斜角对临界流量影响的研究

针对旋转液膜反应器的不同倾斜角和不同夹缝宽度下的临界流量进行了数值模拟。结果表明,对给定的转速,临界流量与倾斜角之间大致呈二次抛物的关系,并且存在临界角使得反应器的临界流量达到最大;当转速增大时,相应的临界角会递减,并最终趋于一个稳定值;当夹缝宽度变小时,这个稳定值几乎不变。     

Solar activity effects of the ionosphere: A brief review

Solar radiation, which varies over multiple temporal scales, modulates remarkably the evolution of the ionosphere. The solar activity dependence of the ionosphere is a key and fundamental issue in ionospheric physics, providing information essential to understanding the variations in the ionosphere and its processes. Selected recent studies on solar activity effects of the ionosphere are briefly reviewed in this report. This report focuses on (1) observations of solar irradiance at X-ray and extreme ultraviolet wavelengths and the outstanding problems of solar proxies, in the view of ionospheric studies, (2) new findings and improved representations of the features of the solar activity dependence of ionospheric key parameters and the corresponding physical processes, (3) possible phenomena in the ionosphere under extremely high and low solar activity conditions that are unique, as indicated by historical solar datasets and the deep solar minimum of solar cycle 23/24, and (4) statistical studies and model simulations of the ionosphere response to solar flares. The above-mentioned studies provide new clues for comprehensively explaining basic processes in the ionosphere and improving the prediction capability of ionospheric models and related applications.     

m≥n的结式消元法

设一个多项式方程组中的方程个数为m >0 ,变元个数为n>0 ,该文在m=n的基组结式消元法的基础上 ,针对m ≥n的情况 ,建立了相应的理论 ,构造了新的消元步骤。用该文方法 ,可将m≥n的一个多项式组 (PS)化成一个三角形组(TS) ={b1(x1) ,b2 (x1,x2 ) ,… ,bn(x1,… ,xn) },使得Zero(PS) Zero(TS) ,且诸bi 在同类多项式中具有最低的度。该文方法在解决空间机构和机器人机构分析与综合等工程问题中具有较大的理论意义和重大的实用价值。     

基于动态特性的新能源挖掘机电池组参数匹配

作为新能源动力挖掘机的动力来源,电池组的性能及合理匹配程度对动力系统及整机性能都有显著影响。基于电池动态特性对挖掘机电池组进行匹配设计,分析了动力电池的放电特性与寿命特性。通过单体电池不同倍率下的放电曲线辨识其Peukert参数,在工况已知的情况下采取工况等效电流,根据Peukert方程实现电池组的参数匹配。最后对日立ZX—70—5A挖掘机进行匹配计算,并进行实验,验证了该匹配方法的有效性和实用性。     

New discoveries from the classic Quaternary mammalian fossil area of Yanjinggou, Chongqing, and their chronological explanations

Yanjinggou in Wanzhou District of Chongqing is one of the earliest reported and most famous Quaternary mammalian fossil areas in China. The fauna from this area used to be taken as a benchmark for the biochronological comparison of Quaternary paleontology of South China, but the chronology of this fauna has many controversies for the lack of exact locational and stratigraphical records. The present article, on the basis of recent investigations and discoveries, discusses and explains the distribution and biochronology of the mammalian faunas in the Yanjinggou area. The newly discovered Dayakou fissure fauna, including Rhizomys troglodytes, Homotherium sp., Panthera pardus, Stegodon orientalis, Dicerorhinus sumatrensis, Hesperotherium sinense, Sus sp., Cervavitus fenqii, Cervus sp. and Muntiacus sp., is correlated to the middle Early Pleistocene. The presence of Early Pleistocene mammalian fauna in the Yanjinggou area is therefore confirmed. The “Wanhsien fauna” or “Yenchingkou (=Yanjinggou) fauna” as a Mid-Late Pleistocene biostratigraphical datum should be abandoned. The Dayakou fauna and the Upper Cave fauna of Pingba, both in the Yanjinggou area, are correlated to the middle Early Pleistocene and the early Middle Pleistocene in age, respectively.     

葡萄糖炭基固体酸催化制备生物柴油

以葡萄糖为原料,在200℃下炭化2h,130℃磺化2h,制得葡萄糖炭基固体酸催化剂。用此催化剂催化油酸与甲醇的酯化反应,考察酯化反应条件对油酸转化率的影响,结果表明：当醇油物质的量比为10：1、剂油比（催化剂与油酸的质量比）为0.07时,在70℃下反应7h,油酸转化率最高,达到95.79%。     

求和或积分号内求导方法在物理学中的应用

总结归纳了在物理学中求和或积分号内的求导方法，并给出了主要应用实例。