scholarly journals Behavior of electron density in the ionosphere over Norilsk during the period of declining solar activity

2021 ◽  
Vol 7 (2) ◽  
pp. 70-73
Author(s):  
Olga Yakovleva ◽  
Galina Kushnarenko ◽  
Galina Kuznetsova
Keyword(s):  
Experimental Data ◽  
Solar Activity ◽  
Electron Density ◽  
Empirical Model ◽  
High Latitude ◽  
Geomagnetic Disturbances ◽  
Ionospheric Layer ◽  
Annual Variations ◽  
Latitude Station ◽  
Semi Empirical

We report the results of approximation of electron density Ne array obtained with a digisonde at the high-latitude station Norilsk (69.40° N, 88.10° E) during years of declining solar activity (2003–2006). The calculations are made using the author's semi-empirical model with new coefficients calculated specifically for the station Norilsk. We obtain altitudinal changes of annual variations in daily Ne at heights of the ionospheric layer F1 (120–200 km). Approximation of experimental data describes Ne quite satisfactorily at these heights. Nevertheless, there are periods with quite pronounced deviations of model values from the experiment. The presence of significant geomagnetic disturbances during these periods is probably one of the reasons for such deviations.

scholarly journals Behavior of electron density in the ionosphere over Norilsk during the period of declining solar activity

2021 ◽  
Vol 7 (2) ◽  
pp. 77-80
Author(s):  
Olga Yakovleva ◽  
Galina Kushnarenko ◽  
Galina Kuznetsova
Keyword(s):  
Experimental Data ◽  
Solar Activity ◽  
Electron Density ◽  
Empirical Model ◽  
High Latitude ◽  
Geomagnetic Disturbances ◽  
Ionospheric Layer ◽  
Annual Variations ◽  
Latitude Station ◽  
Semi Empirical

We report the results of approximation of electron density Ne array obtained with a digisonde at the high-latitude station Norilsk (69.40° N, 88.10° E) during years of declining solar activity (2003–2006). The calculations are made using the author's semi-empirical model with new coefficients calculated specifically for the station Norilsk. We obtain altitudinal changes of annual variations in daily Ne at heights of the ionospheric layer F1 (120–200 km). Approximation of experimental data describes Ne quite satisfactorily at these heights. Nevertheless, there are periods with quite pronounced deviations of model values from the experiment. The presence of significant geomagnetic disturbances during these periods is probably one of the reasons for such deviations.

scholarly journals Electron density at F1-layer heights in the last solar minimum (2007–2009)

2018 ◽  
Vol 4 (1) ◽  
pp. 61-63
Author(s):  
Галина Кушнаренко ◽  
Galina Kushnarenko ◽  
Ольга Яковлева ◽  
Olga Yakovleva ◽  
Галина Кузнецова ◽  
...  
Keyword(s):  
Characteristic Feature ◽  
Electron Density ◽  
Empirical Model ◽  
Solar Minimum ◽  
Ionospheric Physics ◽  
Annual Variations ◽  
Ionospheric Station ◽  
Semi Empirical

We present the results of the analysis of annual variations in daily electron density (N) at heights 140–160 km for the last solar minimum (2007–2009) obtained from digisonde measurements at the ionospheric station Irkutsk (52 °N, 104 °E). New coefficients of the known semi-empirical model (SEM) describing the connection between N and thermospheric characteristics are calculated to identify regularities of these variations. We have revealed that a characteristic feature of the annual N variations during the solar minimum is a change in their phase by 180° in a relatively narrow altitude interval (170–180 km). These results and the new SEM coefficients are original and important for atmospheric and ionospheric physics.

scholarly journals Electron density at F1-layer heights in the last solar minimum (2007–2009)

2018 ◽  
Vol 4 (1) ◽  
pp. 72-75
Author(s):  
Галина Кушнаренко ◽  
Galina Kushnarenko ◽  
Ольга Яковлева ◽  
Olga Yakovleva ◽  
Галина Кузнецова ◽  
...  
Keyword(s):  
Characteristic Feature ◽  
Electron Density ◽  
Empirical Model ◽  
Solar Minimum ◽  
Ionospheric Physics ◽  
Annual Variations ◽  
Ionospheric Station ◽  
Semi Empirical

We present the results of the analysis of annual variations in daily electron density (N) at heights 140–160 km for the last solar minimum (2007–2009) obtained from digisonde measurements at the ionospheric station Irkutsk (52 °N, 104 °E). New coefficients of the known semi-empirical model (SEM) describing the connection between N and thermospheric characteristics are calculated to identify regularities of these variations. We have revealed that a characteristic feature of the annual N variations during the solar minimum is a change in their phase by 180° in a relatively narrow altitude interval (170–180 km). These results and the new SEM coefficients are original and important for atmospheric and ionospheric physics.

scholarly journals Electron density in the F1 layer over Norilsk in 2007–2014

2019 ◽  
Vol 5 (2) ◽  
pp. 124-128
Author(s):  
Галина Кушнаренко ◽  
Galina Kushnarenko ◽  
Ольга Яковлева ◽  
Olga Yakovleva ◽  
Галина Кузнецова ◽  
...  
Keyword(s):  
Solar Activity ◽  
Electron Density ◽  
Solar Minimum ◽  
Annual Variation ◽  
Data Approximation ◽  
Annual Variations ◽  
Ionospheric Station ◽  
Different Seasons ◽  
Semi Empirical ◽  
Maximum Solar Activity

We report the results of the analysis of annual variations in daily electron density (N) for various solar activity conditions — minimum, rise, and maximum (2007–2014) — obtained from digisonde measurements at the ionospheric station Norilsk (69.4° N, 88.1° E). New coefficients of the known semi-empirical model (SEM) describing the connection between N and thermosphere characteristics are calculated to identify regularities of these variations exactly at Norilsk station. The height changes of annual variations in the noon electron density N are obtained in the F1 region (120–200 km). The experimental data approximation describes N quite satisfactorily at these heights in the daytime of different seasons under different solar activity conditions. It is shown that in the years of solar minimum at all heights of the F1 layer the tendency remains for maximum N in summer and for minimum N in winter. In later years and in the year of maximum solar activity, a characteristic feature of the behavior of N is the change in the phase of the annual variation by 180° in the range of heights from 170 to180 km: maximum N is observed in winter; and minimum, in summer.

scholarly journals Electron density in the F1 layer over Norilsk in 2007–2014

2019 ◽  
Vol 5 (2) ◽  
pp. 109-112
Author(s):  
Галина Кушнаренко ◽  
Galina Kushnarenko ◽  
Ольга Яковлева ◽  
Olga Yakovleva ◽  
Галина Кузнецова ◽  
...  
Keyword(s):  
Solar Activity ◽  
Electron Density ◽  
Solar Minimum ◽  
Annual Variation ◽  
Data Approximation ◽  
Annual Variations ◽  
Ionospheric Station ◽  
Different Seasons ◽  
Semi Empirical ◽  
Maximum Solar Activity

We report the results of the analysis of annual variations in daily electron density (N) for various solar activity conditions — minimum, rise, and maximum (2007–2014) — obtained from digisonde measurements at the ionospheric station Norilsk (69.4° N, 88.1° E). New coefficients of the known semi-empirical model (SEM) describing the connection between N and thermosphere characteristics are calculated to identify regularities of these variations exactly at Norilsk station. The height changes of annual variations in the noon electron density N are obtained in the F1 region (120–200 km). The experimental data approximation describes N quite satisfactorily at these heights in the daytime of different seasons under different solar activity conditions. It is shown that in the years of solar minimum at all heights of the F1 layer the tendency remains for maximum N in summer and for minimum N in winter. In later years and in the year of maximum solar activity, a characteristic feature of the behavior of N is the change in the phase of the annual variation by 180° in the range of heights from 170 to180 km: maximum N is observed in winter; and minimum, in summer.

A Hybrid Semi-empirical Model for Lean Blow-Out Limit Predictions of Aero-engine Combustors

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Bin Hu ◽  
Yong Huang ◽  
Jianzhong Xu
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Empirical Model ◽  
The Other ◽  
Model Parameters ◽  
Model Parameter ◽  
Other Hand ◽  
Aero Engine ◽  
Semi Empirical

According to the Lefebvre's model and flame volume (FV) concept, an FV model about lean blow-out (LBO) was proposed by authors in early study. On the other hand, due to the model parameter (FV) contained in FV model is obtained based on the experimental data, FV model could only be used in LBO analysis instead of prediction. In view of this, a hybrid FV model is proposed that combines the FV model with numerical simulation in the present study. The model parameters contained in the FV model are all estimated from the simulated nonreacting flows. Comparing with the experimental data for 11 combustors, the maximum and average uncertainties of hybrid FV model are ±16% and ±10%.

Turbocharger Performance Maps Building Using a Hot Gas Test Stand

2008 ◽  
Author(s):  
Giuliano Gardolinski Venson ◽  
Jose´ Eduardo Mautone Barros
Keyword(s):  
Experimental Data ◽  
Empirical Model ◽  
Quadratic Equation ◽  
Test Stand ◽  
Experimental Methodology ◽  
Maximum Deviation ◽  
Gas Generator ◽  
Hot Gas ◽  
Model Based ◽  
Semi Empirical

This work presents the experimental methodology used in turbochargers tests using a hot gas test stand. The test consists in recording the characteristic curves of the turbochargers, known as flow maps or performance maps. A tubular combustion chamber, designed to operate burning gaseous fuels, is used to drive the set. By using a hot gas generator it’s possible to simulate the real operational condition of the turbine. The experimental configuration allows reproducing the self-sustained turbocharger operation. The test stand instrumentation is based on virtual instrumentation, where acquisition of the sensors and control are made by computer. For the performance maps obtainment, the experimental data are treated through an empirical model based in a quadratic equation involving two variables, mass flow rate and rotational speed. The results present the performance and efficiency maps for the APL-240 Master Power turbocharger, used in commercial heavy trucks. With the results is made a comparison between the experimental maps with the maps gotten through a semi-empirical model based in modified Euler equation. The maximum deviation for compressor and turbine semi-empirical pressure ratios are respectively 8% and 14% in relation to the experimental data.

scholarly journals Geomagnetic disturbances at F1-layer heights under different solar activity conditions over Norilsk

2019 ◽  
Vol 5 (2) ◽  
pp. 113-115
Author(s):  
Галина Кушнаренко ◽  
Galina Kushnarenko ◽  
Ольга Яковлева ◽  
Olga Yakovleva ◽  
Галина Кузнецова ◽  
...  
Keyword(s):  
Solar Activity ◽  
Electron Density ◽  
Main Phase ◽  
Geomagnetic Disturbances ◽  
Long Period ◽  
Ionospheric Station

We analyze the influence of geomagnetic disturbances on the electron density Ne at Norilsk ionospheric station (69° N; 88° E) at F1-layer heights (120–200 km). For the analysis, we have selected 25 moderate and weak geomagnetic disturbances for two seasons — spring and fall — of 2003–2014. Using the Ne values obtained from measurements made with the Norilsk digisonde during this period, we analyze Ne variations during geomagnetic disturbances in spring and fall for a long period of time. We determine the effect of spring-fall asymmetry occurring in all solar activity phases and manifesting itself in a significant decrease in the electron density during the main phase of fall storms at all heights in comparison with quiet days: up to 2.6 times at a height of 200 km and slightly less at lower heights. This phenomenon is not observed during spring disturbances: Ne variations are much weaker.

Acoustic Resonance in Heat Exchanger Tube Bundles—Part II: Prediction and Suppression of Resonance

1987 ◽  
Vol 109 (3) ◽  
pp. 282-288 ◽  
Author(s):  
R. D. Blevins ◽  
M. M. Bressler
Keyword(s):  
Experimental Data ◽  
Heat Exchanger ◽  
Vortex Shedding ◽  
Empirical Model ◽  
Acoustic Resonance ◽  
Heat Exchanger Tube ◽  
Tube Bundles ◽  
Semi Empirical ◽  
Exchanger Tube

In the first part of this series, experimental data were presented which suggest that the acoustic resonance in heat exchanger tube bundles is tied to periodic vortex shedding from the tubes. In this paper, a semi-empirical model for predicting the onset of resonance is developed. This model is compared with experimental data and other models from the literature. Methods of suppressing the resonance are developed and experimental data on their effectiveness are presented.

scholarly journals ESTIMATED RELATIONS BETWEEN THE MAIN THERMOSPHERIC NEUTRAL COMPONENTS AT IONOSPHERIC F1-LAYER HEIGHTSABOVE IRKUTSK IN 2014–2017

2020 ◽  
Vol 6 (3) ◽  
pp. 90-93
Author(s):  
Galina Kushnarenko ◽  
Olga Yakovleva ◽  
Galina Kuznetsova
Keyword(s):  
Solar Activity ◽  
Molecular Oxygen ◽  
Electron Density ◽  
Oxygen Content ◽  
Geomagnetic Activity ◽  
Seasonal Variations ◽  
Molecular Component ◽  
Geomagnetic Disturbances ◽  
Density Measurements ◽  
Atomic Component

We have estimated seasonal variations in the main thermospheric gas components [O]/[N₂] and [O₂]/[O] for the period 2014–2017. We have used the well-known authoring technique and electron density measurements made with the Irkutsk digisonde (52° N, 104° E) at ionospheric F1-layer heights under different geomagnetic activity conditions. We have found that at these heights during geomagnetic disturbances in all seasons the molecular component of the neutral composition of the thermosphere increases and the atomic component decreases. In comparison with 2014, [O₂]/[O] values increased by 2017 under quiet and disturbed geomagnetic conditions: up to 30 % and 20 % in summer and spring respectively; up to 10 % in winter and autumn. The [O]/[N₂] ratio decreased by an average of 15 % by 2017. The assumption has been confirmed that in summer under quiet geomagnetic conditions the relative molecular oxygen content [O₂]/[O] increases with decreasing solar activity.

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