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41.
为检测无人机视频中的地面运动目标,提出了一种运动和颜色信息相结合的算法,采用前向运动历史图像来增强独立运动信息和抑制背景噪声,确保完整分割出候选运动区域;提出一种迭代的、基于局部颜色分布比对的方法,去除候选区域中的背景像素,以更准确地提取单个运动目标,算法不仅节约了计算量,还有效降低了误检和漏检的可能性.多组无人机视频的实验结果表明了所提算法的高效性和鲁棒性。  相似文献   
42.
三维表面形貌的功能评定方法   总被引:2,自引:0,他引:2  
三维表面形貌受生成机理的影响 ,与表面功能密切相关 ,对表面的功能评定至关重要。论述了三维表面功能评定的各种方法 ,如最小二乘多项式拟合、滤波、Motif法和分形方法 ,并分析归纳了存在的问题和发展趋势。  相似文献   
43.
20世纪60年代初,四人小组在钱学森先生直接指导下为发展我国人造卫星进行早期准备工作。文章详细介绍了四人小组在钱学森先生指导下搜集学习国外有关卫星和空间技术的资料,编制《1964-1973年中国空间技术发展规划》(草案),为大学生讲授星际航行概论课,以及担任星际航行座谈会秘书等工作。  相似文献   
44.
孙中山先生的民生主义学说是其三民主义思想的重要组成部分,这一思想的形成经历了一个历史过程。从理论渊源来看,既有中国传统政治思想中民本主义思想的影响,也有对西方资本主义政治经济学有关内容的吸纳,还受到社会主义思想的影响。民生主义提出后,在不同的政治势力之间引发了激烈的争论,这种争论也推动了孙中山三民主义的不断发展演变。民生主义学说对于当代中国民生问题具有重要的启示和借鉴意义。  相似文献   
45.
In a recent paper (Maccone, 2011 [15]) and in a recent book (Maccone, 2012 [17]), this author proposed a new mathematical model capable of merging SETI and Darwinian Evolution into a single mathematical scheme. This model is based on exponentials and lognormal probability distributions, called “b-lognormals” if they start at any positive time b (“birth”) larger than zero. Indeed:
  • 1.Darwinian evolution theory may be regarded as a part of SETI theory in that the factor fl in the Drake equation represents the fraction of planets suitable for life on which life actually arose, as it happened on Earth.
  • 2.In 2008 (Maccone, 2008 [9]) this author firstly provided a statistical generalization of the Drake equation where the number N of communicating ET civilizations in the Galaxy was shown to follow the lognormal probability distribution. This fact is a consequence of the Central Limit Theorem (CLT) of Statistics, stating that the product of a number of independent random variables whose probability densities are unknown and independent of each other approached the lognormal distribution if the number of factors is increased at will, i.e. it approaches infinity.
  • 3.Also, in Maccone (2011 [15]), it was shown that the exponential growth of the number of species typical of Darwinian Evolution may be regarded as the geometric locus of the peaks of a one-parameter family of b-lognormal distributions constrained between the time axis and the exponential growth curve. This was a brand-new result. And one more new and far-reaching idea was to define Darwinian Evolution as a particular realization of a stochastic process called Geometric Brownian Motion (GBM) having the above exponential as its own mean value curve.
  • 4.The b-lognormals may be also be interpreted as the lifespan of any living being, let it be a cell, or an animal, a plant, a human, or even the historic lifetime of any civilization. In Maccone, (2012 [17, Chapters 6, 7, 8 and 11]), as well as in the present paper, we give important exact equations yielding the b-lognormal when its birth time, senility-time (descending inflexion point) and death time (where the tangent at senility intercepts the time axis) are known. These also are brand-new results. In particular, the σ=1 b-lognormals are shown to be related to the golden ratio, so famous in the arts and in architecture, and these special b-lognormals we call “golden b-lognormals”.
  • 5.Applying this new mathematical apparatus to Human History leads to the discovery of the exponential trend of progress between Ancient Greece and the current USA Empire as the envelope of the b-lognormals of all Western Civilizations over a period of 2500 years.
  • 6.We then invoke Shannon's Information Theory. The entropy of the obtained b-lognormals turns out to be the index of “development level” reached by each historic civilization. As a consequence, we get a numerical estimate of the entropy difference (i.e. the difference in the evolution levels) between any two civilizations. In particular, this was the case when Spaniards first met with Aztecs in 1519, and we find the relevant entropy difference between Spaniards an Aztecs to be 3.84 bits/individual over a period of about 50 centuries of technological difference. In a similar calculation, the entropy difference between the first living organism on Earth (RNA?) and Humans turns out to equal 25.57 bits/individual over a period of 3.5 billion years of Darwinian Evolution.
  • 7.Finally, we extrapolate our exponentials into the future, which is of course arbitrary, but is the best Humans can do before they get in touch with any alien civilization. The results are appalling: the entropy difference between aliens 1 million years more advanced than Humans is of the order of 1000 bits/individual, while 10,000 bits/individual would be requested to any Civilization wishing to colonize the whole Galaxy (Fermi Paradox).
  • 8.In conclusion, we have derived a mathematical model capable of estimating how much more advanced than humans an alien civilization will be when SETI succeeds.
  相似文献   
46.
美国军用喷气燃料发展综述   总被引:4,自引:0,他引:4  
以JP和RJ系列燃料为主线,系统地回顾了美国军用喷气燃料发展的历史与成就,着重论述了高密度燃料和吸热碳氢燃料两大军用燃料领域的关键技术,归纳了美国在这两大技术方面的研究历程和最新进展,对喷气燃料的发展前景和可能的研究方向作了展望。  相似文献   
47.
星载被动微波遥感是指利用高灵敏度接收机通过接收场景和目标的自然微波辐射来提取目标信息的一种遥感手段。被动微波遥感又称微波辐射计遥感。人类利用微波辐射计从空间进行对地遥感已有50多年的历史。目前,星载微波辐射计已经成为气象和海洋卫星的主载荷,在数值天气预报、海洋环境监测和全球变化研究中发挥着越来越重要的作用。本文分析了国内外星载被动微波遥感技术与应用进展,以及被动微波遥感技术发展趋势及其关键技术问题,针对中国星载被动微波遥感的定量化应用,在数据与数据处理流程,算法标准化、亮温和反演参数的定标/检验标准化等方面提出了一些思考和建议,以期望被动微波遥感数据被越来越广泛地得到应用,最大限度地提升星载地球被动微波遥感技术的应用效能。  相似文献   
48.
数据仓库通常按多维模型组织数据,随时间的推移,维度不可避免地会发生变化,此时,需要及时对维度进行更新,以免影响数据仓库中数据的准确性.首先从理论上总结了数据仓库系统中维度更新的经典策略.针对复杂需求,需要混合使用基本渐变维度来实现更新,同时提出了一种将清除旧数据和保存历史相结合的方法,可进一步提高决策分析的高效性.  相似文献   
49.
Current geophysical knowledge of the planet Mercury is based upon observations from ground-based astronomy and flybys of the Mariner 10 spacecraft, along with theoretical and computational studies. Mercury has the highest uncompressed density of the terrestrial planets and by implication has a metallic core with a radius approximately 75% of the planetary radius. Mercury’s spin rate is stably locked at 1.5 times the orbital mean motion. Capture into this state is the natural result of tidal evolution if this is the only dissipative process affecting the spin, but the capture probability is enhanced if Mercury’s core were molten at the time of capture. The discovery of Mercury’s magnetic field by Mariner 10 suggests the possibility that the core is partially molten to the present, a result that is surprising given the planet’s size and a surface crater density indicative of early cessation of significant volcanic activity. A present-day liquid outer core within Mercury would require either a core sulfur content of at least several weight percent or an unusual history of heat loss from the planet’s core and silicate fraction. A crustal remanent contribution to Mercury’s observed magnetic field cannot be ruled out on the basis of current knowledge. Measurements from the MESSENGER orbiter, in combination with continued ground-based observations, hold the promise of setting on a firmer basis our understanding of the structure and evolution of Mercury’s interior and the relationship of that evolution to the planet’s geological history.  相似文献   
50.
马克思的历史意识在继承西方历史意识一般内容的基础上,坚持历史意识知识论和方法论的有机统一,唯物辩证地分析了资本主义社会形态的历史合理性。在全球化的态势下,运用马克思主义的历史意识,可以看出资本主义社会基本矛盾在旧有矛盾末获根本解决的前提下,又呈现出一些新的特点,主要表现为危机现象在非资本主义制度国家出现的可能。  相似文献   
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