月球勘测者"月球勘测轨道器"

美国计划在未来十年内重返月球,向月球发射机器人月球登陆器,并再次实现载人登月.为了给这一宏伟计划做准备,NASA将在2008年十月发射"月球勘测轨道器"(LRO).     

Prospecting in glaciated terrain-integrating airborne and Landsat MSS

The effects of a glacially enriched zone of trace elements on soils and vegetation in the Thetford Mines area of Quebec were investigated using ground information plus digital Multispectral Scanner (MSS) data from airborne and Landsat sensors. The enriched zone was developed during the last glaciation when a southeastward flowing glacier eroded and dispersed an ultrabasic outcrop that had anomalous levels of Ni, Cu, Co, Cr, Mg and Fe.The dispersal train of enriched trace elements was detectable over an area at least 70 × 15 km ‘down-ice’ from the outcrop. In this zone total Ni concentrations in the soil ranged from background levels of 10 ppm to levels in excess of 1800 ppm. The dominant tree species, $\text{Abies}$$\text{balsamea}$ (balsam fir) and $\text{Picea glauca}$ (white spruce) reflect the soil anomaly with higher concentrations of trace elements in their tissue and lower concentrations of chlorophyll.An unsupervised enhancement of Landsat imagery showed that a tonal discontinuity was caused by a vegetation segregation related to the heavy metal enrichment soils. A detailed study based on Landsat MSS data was able to establish regional patterns of chlorophyll production by certain plant species closely related to the ultrabasic dispersal train. Multi-channel airborne MSS data confirmed the Landsat soil-plant patterns.     

实现机队的最大价值

KealizingtheGreatestValuefromYourFleet编者按：经营性租赁对于中国航空界来说已不是什么新概念，中国南方航空公司就曾在国内率先采用经营性租赁并收到了良好的效果。但是，与传统的购买飞机的航空公司运营方式相比，经营性租赁所占的比例仍较低。本文从经济学的角度详细论述了这种租赁方式的优点，它能令航空公司拥有一文灵活的机队，而无需占用过多的资金，应该说这对于那些新成立的航空公司，或急于占领市场的承运人来说无疑具有十分重要的意义。目前，在经历了1998年亚洲金融危机后，亚太地区，尤其是中国的航空公司普遍面临着效益…     

Application of the Spatial Spectral Power Density to the Calculation of Resolution Limits

Resolution as a function of aperture length in the presence of phase errors is investigated with the aid of the spatial power spectral density. Numerical calculations are made for power spectra thought to be appropriate for phase errors due to atmospheric turbulence. Both Gaussian and uniform illumination are considered, and the results obtained here are compared with those reported by Brown and Riordan [2].