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1.
认知雷达作为一种全新的智能化雷达概念,可以有效提升雷达在复杂地理和电磁环境中的探测性能,被认为是未来雷达发展的方向。针对认知的基本概念,探讨了认知雷达的基本内涵和概念,并提出了层次化的知识体系和处理流程,给出了认知雷达的系统架构。 相似文献
2.
Although considerations of discourse coherence and cognitive processing suggest that communicators should adopt consistent perspectives when describing spatial scenes, in many cases they switch perspectives. Ongoing research examining cognitive costs indicates that these are small and exacted in establishing a mental model of a scene but not in retrieving information from a well-known scene. A perspective entails a point of view, a referent object, and terms of reference. These may change within a perspective, exacting cognitive costs, so that the costs of switching perspective may not be greater than the costs of maintaining the same perspective. Another project investigating perspective choice for self and other demonstrates effects of salience of referent object and ease of terms of reference. Perspective is mixed not just in verbal communications but also in pictorial ones, suggesting that at times, switching perspective is more effective than maintaining a consistent one. 相似文献
3.
Toshinori Kuwahara Felix Bhringer Albert Falke Jens Eickhoff Felix Huber Hans-Peter Rser 《Acta Astronautica》2009,65(11-12):1616-1627
Flying Laptop is the first small satellite developed by the Institute of Space Systems at the Universität Stuttgart. It is a test bed for an on-board computer with a reconfigurable, redundant and self-controlling high computational ability based on the field programmable gate arrays (FPGAs). This Technical Note presents the operational concept and the on-board payload data processing of the satellite. The designed operational concept of Flying Laptop enables the achievement of mission goals such as technical demonstration, scientific Earth observation, and the payload data processing methods. All these capabilities expand its scientific usage and enable new possibilities for real-time applications. Its hierarchical architecture of the operational modes of subsystems and modules are developed in a state-machine diagram and tested by means of MathWorks Simulink-/Stateflow Toolbox. Furthermore, the concept of the on-board payload data processing and its implementation and possible applications are described. 相似文献
4.
由于光子技术的宽带和低损耗优势,微波光子技术已经在电子对抗领域中尤其是在微波信号的产生、处理、控制及传输等方面引起了强烈关注.着重阐述了微波信号的光子方法产生及处理、光子微波滤波器、光真延时波束形成以及光学A/D模数转换等技术,最后给出了结论. 相似文献
5.
《Acta Astronautica》2010,66(11-12):1616-1627
Flying Laptop is the first small satellite developed by the Institute of Space Systems at the Universität Stuttgart. It is a test bed for an on-board computer with a reconfigurable, redundant and self-controlling high computational ability based on the field programmable gate arrays (FPGAs). This Technical Note presents the operational concept and the on-board payload data processing of the satellite. The designed operational concept of Flying Laptop enables the achievement of mission goals such as technical demonstration, scientific Earth observation, and the payload data processing methods. All these capabilities expand its scientific usage and enable new possibilities for real-time applications. Its hierarchical architecture of the operational modes of subsystems and modules are developed in a state-machine diagram and tested by means of MathWorks Simulink-/Stateflow Toolbox. Furthermore, the concept of the on-board payload data processing and its implementation and possible applications are described. 相似文献
6.
This article considers the problems to be discussed at the WARC-ORB 85 Conference from the perspective of the developing countries. Two main concerns have been expressed by developing countries: access to the geostationary orbit and the technical and financial burdens imposed by technical standards for satellites and earth stations. It is argued that cooperation in outer space particularly in the field of telecommunications is essential, and that programmes such as the UN technical assistance programmes offer the basis for such cooperation. 相似文献
7.
V. V. Sazonov 《Cosmic Research》2011,49(5):407-423
The results of reconstruction of uncontrolled rotational motion of the Foton-12 satellite using the measurement data of onboard sensors are presented. This problem has already been solved successfully
several years ago. The satellite motion was reconstructed using the data of measuring the Earth’s magnetic field. The data
of measuring the angular velocity and microaccelerations by the QSAM system were actually not used for this purpose, since
these data include a clearly seen additional component whose origin was at that time unclear. This component prevented one
from using these data directly for reconstruction of the angular motion. Later it became clear that the additional component
was caused by the Earth’s magnetic field. Discovery of this fact allowed us to make necessary corrections when processing
the QSAM system data and to use them for reconstruction of rotational motion of Foton-12. Below, a modified method of processing the QSAM system data is described together with the results of its application. The
main result is obtained by comparing the motion reconstructed from measurements of angular velocity or acceleration with that
found by way of processing the measurements of the Earth’s magnetic field. Their coincidence turned out to be rather accurate. 相似文献
8.
Heat transfer of thermocapillary convection in a two-layered fluid system under the influence of magnetic field 总被引:1,自引:0,他引:1
Daniele Ludovisi Soyoung S. Cha Narayanan Ramachandran William M. Worek 《Acta Astronautica》2009,64(11-12):1066-1079
Heat transfer of a two-layer fluid system has been of great importance in a variety of industrial applications. For example, the phenomena of immiscible fluids can be found in materials processing and heat exchangers. Typically in solidification from a melt, the convective motion is the dominant factor that affects the uniformity of material properties. In the layered flow, thermocapillary forces can come into an important play, which was first emphasized by a previous investigator in 1958. Under extraterrestrial environments without gravity, thermocapillary effects can be a more dominant factor, which alters material properties in processing. Control and optimization of heat transfer in an immiscible fluid system need complete understanding of the flow phenomena that can be induced by surface tension at a fluid interface. The present work is focused on understanding of the magnetic field effects on thermocapillary convection, in order to optimize material processing. That is, it involves the study of the complicated phenomena to alter the flow motion in crystal growth. In this effort, the Marangoni convection in a cavity with differentially heated sidewalls is investigated with and without the influence of a magnetic field. As a first step, numerical analyzes are performed, by thoroughly investigating influences of all pertinent physical parameters. Experiments are then conducted, with preliminary results, for comparison with the numerical analyzes. 相似文献
9.
激光全波形测距以宽带高灵敏探测技术高保真获取、记录激光探测主回波信号,进行全数字处理和子波分析,解析其时域、空域、频域信息,获取高精度距离、目标分布特征,是提高星载测距仪测距精度、能力、空间配准精度的重要手段。文章对比分析了全波形和阈值法2种激光测距的原理,总结全波形测距的优势,梳理了其技术难点,重点对全波形回波数据处理进行了研究,给出了数据处理算法,实现了复杂多峰回波波形的高斯分解,得到光斑区域内目标相对高程分布,仿真验证了算法的可行性,通过计算不同信噪比下的高程解算误差,得到了误差随信噪比的变化趋势。 相似文献
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星载激光测高技术是对地观测系统中最为核心和前沿的信息获取技术之一,因其具有探测方向性好、测距精度高等特点,在地球科学领域中体现出了巨大的应用潜力。在ICESat/GLAS测高地面数据处理系统的基础上,针对将于今年发射的高分七号卫星的载荷特点,设计了一套星载激光测高地面数据处理系统软件。该软件可实现对星载激光测高数据的地面处理并生成3级数据产品,包含激光能量计算、波形分解和激光脚点定位等,以及相应各级产品的数据质量控制处理。利用高分七号仿真数据对该软件进行相应的性能测试,测试结果表明:该系统软件基本满足需求,已初步具备星载激光测高地面数据处理能力。 相似文献
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D.I.S.C: Decipherment Impact of a Signal's Content.The authors present a numerical method to characterise the significance of the receipt of a complex and potentially decipherable signal from extraterrestrial intelligence (ETI). The purpose of the scale is to facilitate the public communication of work on any such claimed signal, as such work proceeds, and to assist in its discussion and interpretation.Building on a “position” paper rationale, this paper looks at the DISC quotient proposed and develops the algorithmic steps and comprising measures that form this post detection strategy for information dissemination, based on prior work on message detection, decipherment. As argued, we require a robust and incremental strategy, to disseminate timely, accurate and meaningful information, to the scientific community and the general public, in the event we receive an “alien” signal that displays decipherable information. This post-detection strategy is to serve as a stepwise algorithm for a logical approach to information extraction and a vehicle for sequential information dissemination, to manage societal impact.The “DISC Quotient”, which is based on signal analysis processing stages, includes factors based on the signal's data quantity, structure, affinity to known human languages, and likely decipherment times. Comparisons with human and other phenomena are included as a guide to assessing likely societal impact. It is submitted that the development, refinement and implementation of DISC as an integral strategy, during the complex processes involved in post detection and decipherment, is essential if we wish to minimize disruption and optimize dissemination. 相似文献
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As a result of processing long (up to 144 h) series of sunspot magnetograms obtained on the SOHO (Solar and Heliospheric Observatory) spacecraft with the MDI (Michelson Doppler Imager) instrument it is shown that the mode
with a period of 800–1300 min is a limiting low-frequency oscillation mode of the magnetic field of a sunspot as a whole.
Its period is essentially and nonlinearly depends on the sunspot magnetic field strength. In addition to this mode, higher
harmonics are also revealed in the sunspot oscillation spectra in the bands 40–45, 60–80, 135–170, 220–250, and 480–520 min.
The oscillation power in these bands monotonically and rapidly decreases with increasing frequency, which is characteristic
for overtones arising due to the nonlinear nature of oscillations. The limiting oscillation mode stably exists in sunspots
for 1.5–2 days, which coincides with the average lifetime of a supergranular cell. The mode with the period of 35–48 h observed
in the power spectrum is not an eigen mode of sunspots, because its period is independent of its magnetic field strength.
Probably, it occurs as a quasiperiod of an external exciting force caused by disturbances from supergranular cells surrounding
the sunspot. 相似文献
17.
本文针对当前的病毒邮件检测存在的缺陷,利用危险模式的运行机理.建立起一种新型的基于危险模式免疫算法的自适应病毒邮件检测系统模型.系统突出的显出其处理的高效性以及自适应进化更新过程,该方法的提出给邮件安全领域提供了一种新的研究思路. 相似文献
18.
本文针对当前的病毒邮件检测存在的缺陷,利用危险模式的运行机理。建立起一种新型的基于危险模式免疫算法的自适应病毒邮件检测系统模型。系统突出的显出其处理的高效性以及自适应进化更新过程,该方法的提出给邮件安全领域提供了一种新的研究思路。 相似文献
19.
Philippe Ailleris 《Acta Astronautica》2011,68(1-2):2-15
With the commemoration in October 2007 of the Sputnik launch, space exploration celebrated its 50th anniversary. Despite impressive technological and scientific achievements the fascination for space has weakened during the last decades. One contributing factor has been the gradual disappearance of mankind's hope of discovering extraterrestrial life within its close neighbourhood. In striking contrast and since the middle of the 20th century, a non-negligible proportion of the population have already concluded that intelligent beings from other worlds do exist and visit Earth through space vehicles popularly called Unidentified Flying Objects (UFOs). In light of the continuous public interest for the UFO enigma symbolized by the recent widely diffused media announcements on the release of French and English governmental files; and considering the approach of broadening the strategies of the “Active SETI” approach and the existence of a rich multi-disciplinary UFO documentation of potential interest for SETI; this paper describes some past scientific attempts to demonstrate the physical reality of the phenomena and potentially the presence on Earth of probes of extraterrestrial origin. Details of the different instrumented field studies deployed by scientists and organizations during the period 1950–1990 in the USA, Canada and Europe are provided. In conclusion it will be argued that while continuing the current radio/optical SETI searches, there is the necessity to maintain sustaining attention to the topic of anomalous aerospace phenomena and to develop new rigorous research approaches. 相似文献
20.
T. Beuselinck C. Van Bavinchove V. I. Abrashkin A. E. Kazakova V. V. Sazonov 《Cosmic Research》2010,48(3):246-259
The results of reconstruction of rotational motion of the Foton M-3 satellite during its uncontrolled flight in September 2007 are presented. The reconstruction was performed by processing
the data of onboard measurements of the Earth’s magnetic field obtained by the DIMAC instruments. The measurements were carried
out continuously throughout the flight, but the processing technique dealt with the data portions covering time intervals
of a few orbital revolutions. The data obtained on each such interval were processed jointly by the least squares method with
using integration of the equations of satellite motion relative to its center of mass. When processing, the initial conditions
of motion and the used mathematical model’s parameters were estimated. The results of processing 16 data sets gave us complete
information about the satellite motion. This motion, which began at a low angular velocity, had gradually accelerated and
in five days became close to the regular Euler precession of an axisymmetric solid body. At the end of uncontrolled flight
the angular velocity of the satellite relative to its lengthwise axis was 0.5 deg/s; the angular velocity projection onto
the plane perpendicular to this axis had a magnitude of about 0.18 deg/s. 相似文献