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Chakrabarti S Marchant WT Kaplan GC Dobson CA Jernigan JG Lampton ML Malina RF 《Acta Astronautica》1989,19(6-7):467-472
The University of California at Berkeley (UCB) is a member of a university consortium involved in telescience testbed activities under the sponsorship of NASA. Our Telescience Testbed Project consists of three experiments using flight hardware being developed for the Extreme Ultraviolet Explorer project at UCB's Space Sciences Laboratory. The first one is a teleoperation experiment investigating remote instrument control using a computer network such as the Internet. The second experiment is an effort to develop a system for operation of a network of remote workstations allowing coordinated software development, evaluation, and use by widely dispersed groups. The final experiment concerns simulation as a method to facilitate the concurrent development of instrument hardware and support software. We describe our progress in these areas. 相似文献
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Hypotheses of global wildfires following the Cretaceous-Tertiary (KT) boundary impact are supported by high concentrations of elemental carbon (3.6 mg cm(-2)) and soot (1.8 mg cm(-2)) in DSDP Site 465, which was located several thousand kilometers from potential continental sources at 65 Ma. Soot is not preserved at four other central Pacific KT localities, but this is attributed to loss during oxic diagenesis. We find no evidence for wildfires related to major impacts in the late Eocene or to Ir anomalies and extinctions in the late Cenomanian. 相似文献
255.
We evaluated the astrobiological potential of the major classes of geologic units on Europa with respect to possible biosignatures preservation on the basis of surface geology observations. These observations are independent of any formational model and therefore provide an objective, though preliminary, evaluation. The assessment criteria include high mobility of material, surface concentration of non-ice components, relative youth, textural roughness, and environmental stability. Our review determined that, as feature classes, low-albedo smooth plains, smooth bands, and chaos hold the highest potential, primarily because of their relative young age, the emplacement of low-viscosity material, and indications of material exchange with the subsurface. Some lineaments and impact craters may be promising sites for closer study despite the comparatively lower astrobiological potential of their classes. This assessment will be expanded by multidisciplinary examination of the potential for habitability of specific features. 相似文献
256.
Baxter S 《Journal of the British Interplanetary Society》2005,58(3-4):138-142
In the very long term, how could humans colonise the Galaxy? Colonisation cannot be centrally controlled; deeper drives must be tapped. It may take centuries to colonise the nearest stars: it may be a 'programme' like the Industrial Revolution, fuelled by entrepreneurship. To build a respectable interstellar empire may take millennia. Religions are similar multigenerational projects. Perhaps colonists will be motivated by appropriate creeds. To win the Galaxy, starship technology must persist for tens or hundreds of millennia. Homo erectus made the same hand-axe for a million years. The driver was biological, not conscious. Perhaps to our descendants starships will be like peacock tails. 相似文献
257.
Quantification of spatial structure of human proximal tibial bone biopsies using 3D measures of complexity 总被引:2,自引:0,他引:2
Saparin PI Thomsen JS Prohaska S Zaikin A Kurths J Hege HC Gowin W 《Acta Astronautica》2005,56(9-12):820-830
Changes in trabecular bone composition during development of osteoporosis are used as a model for bone loss in microgravity conditions during a space flight. Symbolic dynamics and measures of complexity are proposed and applied to assess quantitatively the structural composition of bone tissue from 3D data sets of human tibia bone biopsies acquired by a micro-CT scanner. In order to justify the newly proposed approach, the measures of complexity of the bone architecture were compared with the results of traditional 2D bone histomorphometry. The proposed technique is able to quantify the structural loss of the bone tissue and may help to diagnose and to monitor changes in bone structure of patients on Earth as well as of the space-flying personnel. 相似文献
258.
用石墨/环氧(T300/934)预浸料制造上下壁成2°锥度角的盒式梁,然后在钢芯模上用压机固化成型。当压机模板在垂直方向加压时,螺栓提供水平方向成型压力。面内弯曲铜度经3点弯曲试验测定,满足设计要求。 相似文献
259.
稳健(Robust)方法用于观测值的滤波和平滑,为处理其中的跳点或野值提供了一种新方法。通过在滤波器和固定滞后的平滑器推导中使用观测值的伪密度,回归的稳健M估算(Mestimates)可用来进行滤波和固定滞后平滑。这些稳健方法用于跟踪数据,可使有野值存在的观测值的估算性能得以改善。这一估算性能的改善,已经过蒙特卡罗方法用模拟跟踪数据做了估算。 相似文献
260.