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Testing of new ionospheric models along the meridian 110°E over the Northern Hemisphere

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Geodesy and Geodynamics 2022年第6期13卷 544-553页

作者： Olga Maltseva Artem Kharakhashyan Tatyana Nikitenko Institute for Physics Southern Federal University344090Russia

Despite the continuous improvement of the widely used empirical model international reference ionosphere(IRI),the recently appeared new models must be tested worldwide.Testing along the meridians has the advantage of dealing with the latitudinal dependent parameters.This paper uses new models of parameters foF2(critical frequency),TEC(total electron content),andτ(equivalent slab thickness of the ionosphere),which are of great importance for evaluating the effects of space weather.IRI-Plas,NNT2F2,and NTSM models were tested using data from 6 ionosondes located along the meridian 110°E in March 2012.It is shown that the IRI-Plas model provides the closest values to experiment with respect toτ,while the NTSM model provides a rather limited reflection of the latitude dependence.Analyses of foF2(NNT2F2)have shown that,the NNT2F2 model provides good conformity with experimental values in this area,but it is very dependent on the TEC processing method.The latitudinal dependences of foF2 obtained with TEC and polynomial dependenceτ(Appr)showed the presence of positive deviations from medians not only during disturbances but also quiet periods,longitudinally at the meridian.

关键词： Ionosphere Modeling Total electron content critical frequency Meridian 110°E

Mineral dust resuspension under vibration: Onset conditions and the role of humidity

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Particuology 2020年第3期18卷 112-119页

作者： F.J.Balladore J.G.Benito R.O.Unac A.M.Vidales Departamento de Mineria Facultad de Ciencias Fisico Matematicas y NaturalesUniversidad Nacional de San LuisChacabuco 917D5700HHWSan LuisArgentina INFAP CONICETDepartamento de FisicaFacultad de Ciencias Fisico Matematicas y NaturalesUniversidad Nacional de San LuisEjercito de los Andes 950D5700HHWSan LuisArgentina

The vibration of dusty surfaces inevitably causes re-entrainment of particles into the atmosphere.Given that movement of mineral dust particles deposited on a surface begins at a critical frequency (fc) and amplitude,an experimental laboratory study was conducted to determine the onset conditions for resuspension of a vibrated granular soil.We determined the resuspension state diagram as a function of frequency and amplitude of a sinusoidal vibration,the granulometry of the dust and the thickness of the soil bed.The mitigation effect of humidity was also evaluated.critical frequencies ranged between 2.5 and 23 Hz when amplitudes were less than 12 rmm.These results were independent of bed thickness and perturbation type.For all particle sizes observed,fc decreased monotonically with A,contrasting with behavior observed for individual particles.In dry samples,fe for large size classes was markedly less when A was greater than 6 mm;while thefc for fine fractions only decreased once amplitudes reached 10 mm.Experiments with wet granular soils demonstrated that wetting above an optimum humidity did not necessarily impede movement and caused agglomeration.This study provides guidelines for managing resuspension of granular soils subjected to vibrations.

关键词： Resuspension Vibration Granular soil Mineral dust critical frequency Humidity

THE ANALYSIS OF INTRASEASONAL LONG ROSSBY WAVE SPEED IN THE SUBTROPICAL PACIFIC OCEAN

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Journal of Hydrodynamics 2006年第1期18卷 55-62页

作者： LIN Xiao-pei WU De-xing LAN Jian Physical Oceanography Laboratory Ocean University of China Qingdao 266003 China

The analysis of the satellite altimeter data suggests that the propagating speed of intraseasonal long Rossby wave amplified in the subtropical Pacific Ocean is faster than that of first mode baroclinic free Rossby wave predicted by the liner theory and the propagating speed of intrascasonal long Rossby wave reflected in the eastern boundary of Pacific Ocean agrees basically with the liner theory speed of first mode baroelinic free P, ossby wave. If we do not distinguish the two kinds of hmg Rossby waves and estimate the Rossby wave speed in the whole basin, the phase speed is merely 25% higher than the linear theory long Rossby wave speed. The acceleration of the propagating speed of intraseasonal long Rossby wave amplified in the subtropical Pacific Ocean is due to the existence of westward thermolcline mean flow.

关键词： Rossby wave baroclinic instability critical frequency

Behavior of a superconducting bulk in a running high-T_c superconducting maglev system(I):distribution of magnetic and electric field

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Journal of Modern Transportation 2011年第3期19卷 168-175页

作者： Chang Chun HSIEH Cuihua CHENG Chuan KE Yong ZHAO Superconductivity and New Energy Center （SNEC） Southwest Jiaotong University Chengdu 610031 China Superconductivity Research Group School of Materials Science and Engineering University of New South Wales Sydney 2052 NSW Australia

A theoretical model of describing the electromagnetic and thermal dynamics of high-Tc superconducting bulks in a high-Tc superconducting Maglev system is built up.The model contains the effects of hysteresis-type loss,flux flow,flux creep,and thermal diffusion on the superconducting bulks in the Maglev system.As the first stage of this study,the behavior of magnetic and electric fields,as well as the distribution energy flow density in the superconducting bulk is studied.The results show that the flux flow and thermal diffusion affect the behaviors of the electromagnetic field in the high-Tc superconducting bulks in different ways;however,both of them contribute significantly to the energy dissipation of the superconducting bulks when they are used in the Maglev train.

关键词： YBCO AC losses critical frequency self-heating

Analysis of Speeds of Cylinders of Saw Gins and Linters and Determination of critical Frequencies for them

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Engineering（科研） 2020年第10期12卷 715-722页

作者： Akmal Umarov Kamola Ortikova Akramjon Sarimsakov Namangan Institute of Engineering and Technology Namangan Uzbekistan

With an increase in the density of the seed roll in the roll box of the saw gin, the quality indicators of the fiber and seed are poor, energy consumption increases, machine breakdowns increase, and when the density decreases, the performance of the saw gin increases. Therefore, the density control of the seed roll is one of the important problems in the ginning process. The paper proposes a change in the rotation speed of the saw cylinder with a decrease in the diameter of its numerical linear speed and machine productivity. The article describes the problem of regulating the density of a seed roll in a saw gin of the DP series, provides an overview of work on regulating the operation of the machine, determines the dependence of the productivity of gins and linters on the state of the saw system in these machines, as well as changes in the linear speed of the saw by changing its diameter. Also, the critical speed of the gin and linter saw cylinder was determined to prevent resonance. In this case, the Simulation package of the SolidWorks computer program was used. The results of the study made it possible to adjust the speed of the cylinders when changing the diameter of the saws, which improved the productivity of the machine while maintaining the quality of the fiber and seed.

关键词： Cotton Saw Gin Roll Box Seed Roll Productivity Rotation frequency critical frequency Resonance Stiffness Mass Total Effective Mass SolidWorks Simulation

Analysis of the ionospheric anomaly at Great Wall Station,Antarctica

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Chinese Journal of Polar Science 1994年第2期5卷 53-57页

作者：甄卫民曹冲吴健

In this paper, we use an empirical method to derive the height of maximum electron concentration of the F2 region and the effective meridional neutral wind at Great Wall Station, Antarctica. The meridional wind is also calculated with the HWM90 model. Results can be used to explain two anomaly features of ionosphere at Great Wall Station. In summer, peak values of f0F2 appear during nighttime. In winter, especially during June and July, f0F2 decrease dramatically as compared with summer's one.Summer anomaly can be explained by combining effects of two causes:thermospheric winds and solar radiation. An important reason for the anomaly is the location of Great Wall Station, which is in both high geographic latitude and middle geomagnetic latitude.

关键词： neutral wind critical frequency summer anomaly