大气总温传感器误差修正方法研究

大气总温的准确测量对民用飞机的飞行安全至关重要。以古德里奇公司的102CP2AG总温传感器为例．详细论述了总温测量过程中对恢复系数、时间常数、自加热、防冰加热等误差的修正原理与使用方法。     

Electron density profile calculation technique for Autoscala ionogram analysis

An electron density profile model with free parameters is introduced. Initially the parameters are calculated on the basis of the ionospheric characteristics automatically obtained from the ionograms by Autoscala and considering the helio-geophysical conditions. The technique used to adjust the free parameters to the particular ionograms recorded is presented.     

低温动态准双轴拉伸加载下HTPB推进剂的热老化性能

为分析热老化后三组元端羟基聚丁二烯(HTPB)推进剂在低温动态准双轴加载下的性能，开展了不同热加速老化时间、不同温度和应变率条件下推进剂的准双轴拉伸力学性能试验及扫描电镜(SEM)观察试验。试验结果表明：热加速老化前后，推进剂的拉伸曲线趋势、力学性能变化规律及细观损伤形式保持一致，改进型非线性模型能够更好地描述1~100 s -1 应变率范围内典型力学性能参数随热老化时间的非线性变化关系。随温度降低，老化后推进剂的断面形貌由“脱湿”变为AP颗粒断裂，热老化、低温以及高应变率载荷的叠加使得推进剂的细观损伤变得更加严重，但准双轴拉伸时损伤程度相比单轴拉伸时有所减弱。热老化32 d、74 d和98 d后-50 ℃、 14.29 s -1 加载条件下的最大伸长率分别为未老化时室温、0.40 s -1 条件下数值的28.79%、27.58%和25.63%，该参数定义可为分析长期贮存后战术导弹SRM药柱在低温点火条件下结构完整性失效的准则提供数据支持。     

某型机吊声液压系统温升试验现象分析

本文论述了高温对液压系统的影响和液压系统温升较快的原因。从某型机吊声液压系统温升试验现象出发,分析了其产生的原因。提出了改进建议,并指出地面试验与该型机吊声液压系统实际工作环境的区别。     

Stagnation temperature effect on the conical shock with application for air

The aim of this work is to realize a new numerical program based on the development of a mathematical model allowing determining the parameters of the supersonic flow through a conical shock under hypothesis at high temperature, in the context of correcting the perfect gas model. In this case, the specific heat at constant pressure does not remain constant and varies with the increase of temperature. The stagnation temperature becomes an important parameter in the calculation. The mathematical model is presented by the numerical resolution of a system of first-order nonlinear differential equations with three coupled unknowns for initial conditions. The numerical resolution is made by adapting the higher order Runge Kutta method. The parameters through the conical shock can be determined by considering a new model of an oblique shock at high temperature. All isentropic parameters of after the shock flow depend on the deviation of the flow from the transverse direction. The comparison of the results is done with the perfect gas model for low stagnation temperatures, upstream Mach number and cone deviation angle. A calculation of the error is made between our high temperature model and the perfect gas model. The application is made for air.     

Response of the lower atmosphere to intense geomagnetic storms

In this short paper we examine the possible connection between atmospheric parameters measured at low and middle altitudes and geomagnetic storms occurred in 2000 and 2003. For that, from a chain of stations located near the meridian 60°W we compare the storm time values of temperature and wind speed with their standard deviation 2σ obtained from quiet time values. We observed statistically significant variations at several altitudes during the storm recovery phase and after it, both in neutral wind speed and temperature. The results obtained suggest that atmospheric parameters could be affected by geomagnetic storms.     

Comparison of topside electron density computed by ionospheric models and plasma density observed by DMSP satellites

Electron density obtained by IRI (topside options NeQuick and IRI-Corr) and NeQuick models in their standard versions have been compared with plasma density values measured by F13 and F15 DMSP satellites for years of different solar activities. A statistical study of the differences between modeled and experimental data has been carried out to investigate each model performance.     

复合涂层刀具钻削高温合金Inconel 718钻削性能研究

高温合金Inconel 718是一种典型的难加工材料,本文利用DEFORM-3D软件对无涂层、TiC单涂层和TiC/Al₂O₃复合涂层硬质合金刀具进行钻削高温合金Inconel 718的仿真分析,研究在不同钻削条件下复合涂层刀具的切削性能,并进行钻削实验进行验证。结果表明：TiC/Al₂O₃复合涂层刀具能有效降低钻削轴向力和钻削温度,其轴向力降低幅度最高为20%,钻削温度最高降低了35%。通过钻削实验验证了仿真模型的准确性,可为实际钻削加工高温镍基合金Inconel 718中选择涂层种类及钻削参数提供参考。     

Water surface temperature estimation from Landsat 7 ETM+ thermal infrared data using the generalized single-channel method: Case study of Embalse del Río Tercero (Córdoba,Argentina)

Monitoring of warm distribution in water is fundamental to understand the performance and functioning of reservoirs and lakes. Surface water temperature is a key parameter in the physics of aquatic systems processes since it is closely related to the energy fluxes through the water–atmosphere interface. Remote sensing applied to water quality studies in inland waterbodies is a powerful tool that can provide additional information difficult to achieve by other means. The combination of good real-time coverage, spatial resolution and free availability of data makes Landsat system a proper alternative. Many papers have developed algorithms to retrieve surface temperature (principally, land surface temperature) from at-sensor and surface emissivity data. The aim of this study is to apply the single-channel generalized method (SCGM) developed by Jiménez-Muñoz and Sobrino (2003) for the estimation of water surface temperature from Landsat 7 ETM+ thermal bands. We consider a constant water emissivity value (0.9885) and we compare the results with radiative transfer classic method (RTM).     

Solar and magnetic control on night-time enhancement in TEC near the crest of the Equatorial Ionization Anomaly

The ionospheric Total Electron Content (TECs), derived by dual frequency signals from the Global Positioning System (GPS) recorded near the Indian equatorial anomaly region, Bhopal (23.2°N, 77.4°E, Geomagnetic 14.2°N) were analyzed for the period of January, 2005 to February, 2008. The work deals with monthly, diurnal, solar and magnetic activity variations on night-time enhancement in TEC. From a total of 157 night-time enhancements, 75 occur during pre-midnight and 82 post-midnight hours. The occurrence of night-time enhancement in TEC is utmost during summer months, followed by equinox and winter months. The occurrence of night-time enhancement in TEC decreases with increase in solar and magnetic activities. We observed that peak size and half amplitude duration are positively correlated, while time of occurrence of night-time enhancement in TEC and time of peak enhancement are negatively correlated with solar activity. The peak size, half amplitude duration, time of peak enhancement and time of occurrence of night-time enhancement in TEC shows negative correlation with magnetic activity. The results have been compared with the earlier ones and discussed in terms of possible source mechanism responsible for the enhancement at anomaly crest region.