航空公司航空油料成本管理研究

运用成本动因(costdriver)理论,对航空油料成本生成的关键因素进行深入探讨,在理解和把握航空油料成本的内涵和运动规律的基础上,提出一种全新的航空油料成本核算和管理方法,即:以存货管理方法进行航空油料成本核算和管理;以多层面、多动因要素核算、分配和控制航空油料成本。     

Comparing IRI and a regional model with ionosonde measurements in Pakistan

We have used the technique of expansion in Empirical Orthogonal Functions (EOFs) to develop regional models of the critical frequencies of E and F₂ layers (f_oE, f_oF₂), peak height (h_mF₂), and semi-thickness of F₂ layer (Y_mF₂) over Pakistan. In the present study levels of solar activity specified by Smoothed Sunspot Number (R) from 10 to 200 are taken into account. The magnetic dip angle for the model ranges from 30° to 60°. We have compared the regional model and the International Reference Ionosphere (IRI) with measurements of three ionosondes in Pakistan. The model parameters f_oE and f_oF₂ are found overall comparable to the observed hourly median values during daytime at Karachi (geographic latitude = 24.95°N, longitude = 67.13°E, magnetic inclination = 37°), Multan (30.18°N, 71.48°E, 45°) and Islamabad (33.75°N, 73.13°E, 51.5°) during the years 1988, 1996 and 2000. For h_mF₂ the computed values by regional and IRI model for the year 1995 are found close to each other. However, for Y_mF₂the results are better during daytime as compared to nighttime.     

Solar wind electron density and temperature over solar cycle 23: Thermal noise measurements on Wind

We present the solar wind plasma parameters obtained from the Wind spacecraft during more than nine years, encompassing almost the whole solar cycle 23. Since its launch in November 1994 Wind has frequently observed the in-ecliptic solar wind upstream of the Earth’s bow shock. The WIND/WAVES thermal noise receiver was specially designed to measure the in situ plasma thermal noise spectra, from which the electron density and temperature can be accurately determined. We present and discuss histograms of such measurements performed from 1994 to 2003. Using these large data sets, we study the density and core temperature variations with solar activity cycle and with different regimes of the solar wind. We confirm the anticorrelation of the electron density with the sunspot number, and obtain a positive correlation of the core temperature, with the sunspot number.     

The auroral activity during the main phase of magnetic storms

The relationship of auroral activity indices (AE, Kp, SME) with interplanetary medium parameters during the main phase of magnetic storms is studied. For the period 1990–2020, 142 magnetic storms driven by (41) Sheath, (61) CIR, and (40) ICME events are selected. It is found that the correlation coefficient between average values of the SME index and the SW electric field for Sheath (r = 0.75) is close to correlation coefficients for CIR and ICME events. The correlation coefficient between Kp_aver&Esw_aver (r = 0.72) is higher than the correlation coefficient between AE_aver&Esw_aver (r = 0.63) at the main phase of magnetic storms induced by the Sheath events. It is shown that average values of SW dynamic pressure and IMF σB fluctuations correlate each other for all types of SW.     

Effect of gamma irradiation on hyperthermal composting microorganisms for feasible application in space

The composting system is the most efficient method for processing organic waste in space; however, the composting activity of microorganisms can be altered by cosmic rays. In this study, the effect of ionizing irradiation on composting bacteria was investigated. Sequence analyses of amplified 16S rRNA, 18S rRNA, and amoA genes were used to identify hyperthermal composting microorganisms. The viability of microorganisms in compost soil after gamma irradiation was directly determined using LIVE/DEAD BacLight viability kit. The dominant bacterial genera were Weissella cibaria and Leuconostoc sp., and the fungal genera were Metschnikowia bicuspidata and Pichia guilliermondii. Gamma irradiation up to a dose of 10 kGy did not significantly alter the microbial population. Furthermore, amylase and cellulase activities were maintained after high-dose gamma irradiation. Our results show that hyperthermal microorganisms can be used to recycle agricultural and fermented material in space stations and other human-inhabiting facilities on the Moon, Mars, and other planets.     

Comparisons of foF2 with IRI model and equatorial vertical drifts

Measurements of the critical frequency, foF2 recorded over Ibadan: 7.4°N, 3.9°E (geographic), 6°S (dip angle) have been compared with the International Reference Ionosphere (IRI-2007) model for solar maximum geomagnetically quiet conditions, with a view to determining what modifications might bring about better predictions for the model. Our results reveal that the present version of IRI essentially reproduces diurnal trends and the general features of the experimental observations for all seasons, except for nighttime June solstice periods, which the model seriously overestimated. The model errors ranging from 50% to 125% over the four seasons considered in this study. It is also indicated that the percentage relative deviations between the observed and the modeled values vary approximately from −11% to 12% (March), −34% to 11% (June), −16% to 12% (September), and −10% to 13% (December). An unexpected feature of foF2 is obvious and remarkable reduction in values during nighttime June solstice periods compared to that in other seasons. Relationship between equatorial vertical drift and foF2 is also investigated. However, cross correlation analysis reveals strong anti-correlation between vertical drift and critical frequency during the daytime hours, but exceptionally opposite is the case for the nighttime sector. The discrepancies which are noted, particularly during June solstice season are attributed to processes most likely within the thermosphere and from meteorological influences during quiet magnetic conditions.     

Solar activity and human health at middle and low geomagnetic latitudes in Central America

The study of the possible effect of solar variability on living organisms is one of the most controversial issues of present day science. It has been firstly and mainly carried on high latitudes, while at middle and low latitudes this study is rare. In the present review we focused on the work developed at middle and low geomagnetic latitudes of America. At these geomagnetic latitudes the groups consistently dedicated to this issue are mainly two, one in Cuba and the other in Mexico.     

A MHD-turbulence model for solar corona

The disposition of energy in the solar corona has always been a problem of great interest. It remains an open question how the low temperature photosphere supports the occurence of solar extreme phenomena. In this work, a turbulent heating mechanism for the solar corona through the framework of reduced magnetohydrodynamics (RMHD) is proposed. Two-dimensional incompressible long time simulations of the average energy disposition have been carried out with the aim to reveal the characteristics of the long time statistical behavior of a two-dimensional cross-section of a coronal loop and the importance of the photospheric time scales in the understanding of the underlying mechanisms. It was found that for a slow, shear type photospheric driving the magnetic field in the loop self-organizes at large scales via an inverse MHD cascade. The system undergoes three distinct evolutionary phases. The initial forcing conditions are quickly “forgotten” giving way to an inverse cascade accompanied with and ending up to electric current dissipation. Scaling laws are being proposed in order to quantify the nonlinearity of the system response which seems to become more impulsive for decreasing resistivity. It is also shown that few, if any, qualitative changes in the above results occur by increasing spatial resolution.     

F3 layer feature under low and medium solar activity observed at a Chinese low latitude station Fuke

Ionogram observations from the ionosonde at Fuke (9.5°N geomagnetic latitude), a Chinese low latitude station, in 2010–2012 are analyzed to present the features of F3 layer under low and moderate solar activity conditions. Structure of the ionogram, displaying the F3 layer, was more distinct and clear during MSA than LSA periods especially during spring to summer. Start time of occurrence of the F3 layer is about at 0830–0900 LT and is approximately the same for LSA and MSA conditions. The average duration time of the F3 layer occurrence was 181 min per day under F_10.7 = 75 condition, 263 min in F_10.7 = 99 and 358 min in F_10.7 = 125, respectively. The differences of h′F2 and h′F3 exhibited obvious semiannual variation observed at Fuke from March 2010 to June 2012 and increased with increasing solar activity. The difference of foF2 and foF3 in the months February, March, September, October and November is less evident in the middle solar activity period 2011–2012 than the low solar activity 2010 and in the other period it shows a slight increase (0.5 MHz) or keeps constant. The results show that the solar activity dependence of the F3 layer occurrence at low latitude away from the magnetic equator is different from that at near the magnetic equator.