排序方式: 共有34条查询结果,搜索用时 15 毫秒
1.
Klaus Iserland 《Space Policy》1990,6(4):341-343
This article celebrates the tenth birthday of Europe's satellite launch corporation. It was born at a time when expendable launch vehicles were widely believed to be redundant, but has confounded its critics to become the leader in the world commercial satellite launch market. The author notes the milestones on Arianespace's path, and expresses confidence in its ability to the growing competitive challenge of the 1990s. 相似文献
2.
P Todd D M Klaus 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1996,17(6-7):3-10
A wide variety of observations on cells in space, admittedly made under constraining and unnatural conditions in many cases, have led to experimental results that were surprising or unexpected. Reproducibility, freedom from artifacts, and plausibility must be considered in all cases, even when results are not surprising. The papers in the symposium on "Theories and Models on the Biology of Cells in Space" are dedicated to the subject of the plausibility of cellular responses to gravity--inertial accelerations between 0 and 9.8 m/s2 and higher. The mechanical phenomena inside the cell, the gravitactic locomotion of single eukaryotic and prokaryotic cells, and the effects of inertial unloading on cellular physiology are addressed in theoretical and experimental studies. 相似文献
3.
P Todd D M Klaus L S Stodieck J D Smith L A Staehelin M Kacena B Manfredi A Bukhari 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1998,21(8-9):1263-1268
Our understanding of gravitational effects (inertial effects in the vicinity of 1 x g) on cells has matured to a stage at which it is possible to define, on the basis of experimental evidence, extracellular effects on small cells and intracellular effects on eukaryotic gravisensing cells. Yet undetermined is the nature of response, if any, of those classes of cells that are not governed solely by extracellular physical events (as are prokaryotes) and are devoid of obvious mechanical devices for sensing inertial forces (such as those possessed by certain plant cells and sensory cells of animals). This "in-between" class of cells needs to be understood on the basis of the combination of intracellular and extracellular gravity-dependent processes that govern experimentally-measurable variables that are relevant to the cell's responses to modified inertial forces. The forces that certain cell types generate or respond to are therefore compared to those imposed by approximately 1 x g in the context of cytoskeletal action and symmetry-breaking pathways. 相似文献
4.
Ontological Modularity and Spatial Diversity 总被引:1,自引:1,他引:0
5.
Klaus Becher 《Space Policy》1995,11(4):233-238
Control of space-related assets represents a factor of civilian as well as military power. If countries seek unilateral access to space technology for the purpose of aggression against others, international peace and stability are at risk. The author discusses the role of the non-proliferation regime for space technology within an integrated strategy for the promotion of international security and development. He suggests that under certain conditions, allowing the further spread of the use of space-based capabilities can contribute to the stabilization of regional conflict situations. However, certain safeguards, controls and restraints should be required from potential new space powers. 相似文献
6.
Evan A. Thomas Mark M. Weislogel David M. Klaus 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
It is well recognized that water handling systems used in a spacecraft are prone to failure caused by biofouling and mineral scaling, which can clog mechanical systems and degrade the performance of capillary-based technologies. Long duration spaceflight applications, such as extended stays at a Lunar Outpost or during a Mars transit mission, will increasingly benefit from hardware that is generally more robust and operationally sustainable over time. 相似文献
7.
If a camera moves fast while taking a picture, motion blur is induced. There exist techniques to prevent this effect to occur, such as moving the lens system or the CCD chip electro-mechanically. Another approach is to remove the motion blur after the images have been taken, using signal processing algorithms as post-processing techniques. For more than 30 years, numerous researchers have developed theories and algorithms for this purpose, which work quite well when applied to artificially blurred images. If one attempts to use those techniques to real world scenarios, they mostly fail miserably. In order to study why the known algorithms have problems to de-blur naturally blurred images we have built an experimental setup, which produces real blurred images with defined parameters in a controlled environment. For this article we have studied the most important algorithms used for de-blurring, we have analyzed their properties when applied to artificially blurred images and to real images. We propose solutions to make the algorithms fit for purpose. 相似文献
8.
Analysis of a spacecraft life support system for a Mars mission 总被引:1,自引:0,他引:1
This report summarizes a trade study conducted as part of the Fall 2002 semester Spacecraft Life Support System Design course (ASEN 5116) in the Aerospace Engineering Sciences Department at the University of Colorado. It presents an analysis of current life support system technologies and a preliminary design of an integrated system for supporting humans during transit to and on the surface of the planet Mars. This effort was based on the NASA Design Reference Mission (DRM) for the human exploration of Mars [NASA Design Reference Mission (DRM) for Mars, Addendum 3.0, from the world wide web: http://exploration.jsc.nasa.gov/marsref/contents.html.]. The integrated design was broken into four subsystems: Water Management, Atmosphere Management, Waste Processing, and Food Supply. The process started with the derivation of top-level requirements from the DRM. Additional system and subsystem level assumptions were added where clarification was needed. Candidate technologies were identified and characterized based on performance factors. Trade studies were then conducted for each subsystem. The resulting technologies were integrated into an overall design solution using mass flow relationships. The system level trade study yielded two different configurations--one for the transit to Mars and another for the surface habitat, which included in situ resource utilization. Equivalent System Mass analyses were used to compare each design against an open-loop (non-regenerable) baseline system. 相似文献
9.
10.
Determination of relative distances and orientations, as well as motion identification is essential in rendezvous and docking and formation flying tasks. A 3D-image generated by a PMD (photonic mixer device) camera, which employs a phase shift measurement of emitted modulated light to derive distance and color information on each pixel, provides in this contribution the basis for near range motion detection and prediction. A novel algorithm based on rotation- and scale-invariant features commonly used for scan matching in high-resolution images is presented. The performance of the PMD camera and of the proposed data processing is characterized in scenarios, considering factors like relative velocities, rotation dynamics, illumination and optical properties of target surface materials, which are major effects for disturbances in this context. 相似文献