中国气象卫星的发展及应用

文章回顾了中国气象卫星的发展历史、所提供的服务和应用。中国气象卫星是在全球气象卫星发展的浪潮中发展起来的。经过40多年的发展,极轨和静止两个系列的气象卫星已经业务运行。中国的气象卫星工程由卫星、运载火箭、发射、测控和地面应用5大系统组成。地面系统作为气象卫星工程大系统中的重要组成部分,对卫星应用效益起重要的作用,在卫星发射后对卫星有效荷载进行运行管理,实施从卫星下传数据的接收、处理、分发、应用和服务。中国气象卫星投入业务运行以后,为改善天气预报、环境监测和短期气候预测提供了有用的信息。在天气预报领域,为台风、暴雨、冰雹 、暴雪、沙尘暴、龙卷风等灾害性天气的预报提供了更有力的手段;在短期气候预测领域,提供了更多有用的参数,如海表水温、雪盖、植被指数等;在环境监测领域,在洪涝、森林草原火情、沙尘暴、雪灾和海冰等监测中发挥了重要作用。现阶段,中国气象卫星面临的最大机遇和挑战在于提高产品的精度,为定量应用服务。其内容涵盖气象卫星的空间段和地面段,并且与数值天气预报本身也有密切的关系。气象卫星为数值天气预报提供全球资料,数值预报模式为气象卫星提供定量产品推导的背景场。气象卫星与数值天气预报协同工作,才能促进气象卫星应用水平的提高。     

坚持政产学研用 实现中国遥感卫星质量的飞跃

近来,“资源三号测绘卫星”的成功发射和规模化应用引起了高度关注,成果入选2012年中国高等学校十大科技进展。文章简要阐述“资源三号测绘卫星”从立项到应用的历程,探讨政产学研用协同创新模式,叙述“资源三号测绘卫星”的主要性能指标和应用范围。通过与国外同类卫星的比较,表明我国有能力发展一流水平的高分辨遥感卫星,实现我国卫星遥感从有到好的重大转变,推进我国遥感卫星的产业化发展。     

GEO卫星通信中空时协同性能分析

GEO卫星通信的用户下行链路为典型的衰落信道,经卫星转发的信号如果经历大尺度衰落,则用户端接收到的信号将产生大范围失真。该文针对GEO卫星通信的特点,为了提高GEO卫星系统的通信性能,考虑将空时协同技术引入到GEO卫星通信中。并仿真分析了在不同信道环境下,使用不同分集方案时GEO卫星通信系统性能,结果显示使用空时协同技术后,系统的可靠性有明显提高。     

八种国产葱属植物染色体研究

本文对国产葱属Allium 8个种的14个居群的染色体进行了研究。其染色体基数均为x=8，其中7个居群为二倍体(2n=2x=16)，6个居群为四倍体(2n=4x=32)，1个居群为多倍体复合体(2n=4x=32，2n=6x=48，2n=8x=64和2n=9x=72)。并发现随体染色体十分活跃，在多倍体中其数目并不都与其倍性相对应，并有“串状随体”现象出现；在有些类群中其形态变异较大，而随体染色体杂合形式的多态现象也较普遍。本文重点讨论了随体染色体的数目、形态变异及杂合现象在葱属进化中的作用，认为随体染色体形态变异及杂合现象的出现是葱属中遗传变异的重要源泉之一。并对葱属中的染色体基数及种内多倍性问题进行了初步讨论。     

An educational tv satellite for India: a critical assessment

The paper first presents the Indian proposal for an educational TV satellite with countrywide coverage (INSAT), and gives a sketch of the methodology applied in assessing this large-scale communications change in India. Efforts in communications planning should be considered from the point of view of their potential for helping large numbers of people to gain access to information (which is one aspect of the fact that half the Indian population lives in abject poverty). A first overview of the results according to such criteria demonstrates that the Indian proposal will be anything but a success. The satellite system cannot meet the needs of the broad population. On the one hand the project creates a large potential for mobilisation of the masses, on the other it is not in a position to transmit programmers, which in their content are to a minimal degree adapted to the needs of the adults. In the field of school broadcasts and teacher training, sufficient results are only reached by versions of the project which must be ruled out for political reasons. The capacity of the project is too restricted to avoid conflicts between individual states. Furthermore, the project benefits the largest language groups at the expense of the minorities.Some of the results are discussed in detail by way of a comparison of the impressive technical capacities of terms. Alternative projects with greater scope and with a decentralised structure (e.g. radio satellites or cassette systems) would be better than TV satellites, but pose problems of generating the information in suitable form. The bottleneck in communication is as much in the creation of differentiated information, as in the techniques of conveying it to the audiences. The final section discusses the background of the Indian interests in ‘educational satellites’.     

发展空间科学是建设世界科技强国的重要途径

习近平总书记在2016年提出了建设世界科技强国"三步走"的战略,为我们设立了宏伟的目标。要想实现这个目标,我们国家在前沿基础研究领域就必须加大投入,实现重大突破。长期以来,作为发展中国家,我国在空间科技领域的投入,大都用于应用卫星,比如气象卫星、通信卫星等,而在空间科学卫星领域少有投入。纵观世界科技发展,重大基础前沿的突破逐渐依赖于国家重大科技工程,其一是建设地面大科学装置,如加速器、大型天文望远镜等;其二就是在空间科学领域里的投入,发射科学卫星。1957年以来美国等航天强国在空间科学领域里多次获得诺贝尔奖就充分说明了这一领域在实现基础前沿领域重大突破的作用。由此可见,发展空间科学是建设世界科技强国的一个非常重要的方面和实现途径。     

Switching position and range-domain carrier-smoothing-code filtering for GNSS positioning in harsh environments with intermittent satellite deficiencies

Carrier-smoothing-code filtering (CSCF) is widely used in GNSS signal processing to combine code pseudoranges and carrier phases. Position-domain (PD) CSCF is generally more accurate and less sensitive to visible satellite changes than range-domain (RD) CSCF. However, PD-CSCF necessitates at least four visible satellites. Intermittent satellite deficiency with less than four visible satellites is not uncommon in harsh environments like urban canyons. At such deficiency epochs, the PD-CSCF convergence has to break off. This study aims to bridge intermittent deficiency epochs in PD-CSCF without introducing any external information. The proposed solution is called switching RD and PD CSCF in which PD filter is replaced by RD filter at deficiency epochs. Besides detailing the seamless switching algorithms from PD/RD to RD/PD filters, a global RD filter, different from the conventional one, is developed to preserve the correlations among smoothed pseudoranges corresponding to different satellites. Compared to the conventional PD and RD CSCF algorithms, smoother results can be expected from the proposed switching filter, especially after the intermittent deficiency epochs. Experiments are conducted using real BDS signals. Cases with different kinds of deficiency are considered. Superiority of the proposed method is clearly observed from the results.     

面向LEO卫星网的显式TCP方法

提出一种利用TCP接收端卫星TCP流数量和经过路径卫星数这2种网络显式信息来调控发送窗口的新方法.此方法中各TCP流根据自身的不同时延对丢包作出敏感度不同的窗口调整反应,以对应时延越大拥塞反应策略越低效的规律.NS2仿真结果表明,这一方法不仅能在应对信道丢包的同时,提高各不同时延的TCP流的公平性、保证其吞吐量,还能较好地预防星地下行链路的丢包,并提高其带宽利用率.     

中国科学院与“两弹一星”工程

"两弹一星"的成功,是中国大国地位的奠基石。从1955年我国决定发展原子能,到1970年第一颗人造卫星发射成功,在"两弹一星"的研制过程中,中国科学院承担了与核弹、导弹相关的大量配套科技任务,负责整个卫星系统的技术抓总,完成卫星本体的研制,并建立地面测控系统。中国科学院为我国"两弹一星"工程作出了重大贡献。     

中国极轨气象卫星遥感技术的发展

中国极轨气象卫星遥感技术的研究始于20世纪70年代。为获取昼夜云图,1974年开始研制48转/分可见红外扫瞄辐射计,可见和红外图像地面分辨率分别为4和5.8毫弧度。1977年“FY-1”气象卫星进入工程研制,开始使用辐射致冷器冷却的HgCdTe红外探测器研制120转/分扫瞄辐射计,图像地面分辨率均提高到3.6毫弧度。随着HgCdTe探测器性能的提高和数字化技术的进步,1982年开始研制360转/分5通道扫瞄辐射计,其中2个可见光通道用于海洋水色观测,图像地面分辨率1.2毫弧度。1988年9月“FY-1A”卫星首次发射,在1990年9月发射的“FY-1B”卫星上,扫描辐射计稳定工作了2年,图像清晰,红外辐射定标精度优于1K。为同时满足气象和海洋水色观测的需要,1989年提出研制十通道扫瞄辐射计,它不仅设有NOAA卫星AVHRR/3的6个探测通道,还有4个通道分别用于海洋水色观测和大气校正。该仪器装载在1999年5月和2002年5月入轨的“FY-1C”和“FY-1D”卫星上,运行寿命分别超过4年和9年。为发展新的遥感仪器和提高观测能力,在2002年发射的“SZ-3”和“SZ-4”飞船上进行了中分辨率成像光谱仪、多模态微波遥感器、太阳紫外光谱探测仪、地球辐射收支仪的遥感试验,并开展了大气红外分光计的研制,为中国极轨气象卫星从二维图像向三维立体观测建立了技术基础。第二代业务气象卫星“FY-3A”和“FY-3B”分别于2008年5月和2010年11月发射,各装载了10台遥感仪器,获取的数据用于天气预报和气候变化研究。中分辨率成像光谱仪有20个探测通道,可对全球表面状况做较精细的快速重复观测。     

中国遥感发展及其贡献

20世纪60年代,遥感技术在国际上兴起,自我国第一颗人造地球卫星发射以来,中国开始进入空间时代。为适应国家经济社会发展的迫切需要,遥感在我国也受到高度重视,得到快速发展。我国已形成了自己的遥感卫星系列,如气象卫星、海洋卫星、陆地资源卫星、环境与减灾卫星等。灵活、机动性强的航空遥感也在应用中发挥了重大作用。遥感应用是我国发展遥感科学技术的重点,30多年来遥感在我国成功地应用于国家土地资源调查、农作物和森林监测、地质矿产调查、城市发展监测以及海洋和海岸带资源调查等。在洪水、旱涝、林火、地震以及相关的气象和地质灾害发生期间,遥感总是起到关键作用。遥感已成为中国经济社会发展不可或缺的信息支撑。文章将在上述方面进行简要论述,以窥我国遥感发展之一斑。     

组织遗忘、突破式创新与组织绩效研究——基于冗余资源的调节作用

构建了组织遗忘、冗余资源、突破式创新和组织绩效的概念模型,以我国中部省份155家主要地市企业为调查样本,运用PLS-SEM和PROCESS工具实证分析了突破式创新在组织遗忘和组织绩效之间的部分中介作用和冗余资源的负向调节作用。结果表明:组织遗忘对组织绩效具有正向作用,突破式创新在两者之间起到了部分中介作用;冗余资源对组织遗忘与组织绩效之间的间接关系起负向调节作用,并且组织遗忘对组织绩效之间的间接关系只有在冗余资源水平比较低的情况下才比较显著。     

Angular velocity stabilization of underactuated rigid satellites based on energy shaping

Angular velocity stabilization problem for underactuated rigid satellites with only two independent control inputs is investigated, and a novel stabilization control strategy based on energy shaping is presented in this paper. Firstly, a desired closed-loop system with a specific structure is constructed for the control objective. The matching condition and controller structure are determined by equating the underactuated satellite system with the desired system. Moreover, a feasible sufficient condition satisfying the matching condition is derived. By solving the sufficient condition according to three different structures of the satellite inertia tensor matrix, three nonlinear smooth stabilization control laws are obtained, and global asymptotic stability of the related closed-loop system is rigorously proved. Simulation results show effectiveness of the proposed control method.     

中国遥感卫星地面站及其陆地观测卫星数据接收和处理系统

中国遥感卫星地面站是国家重大科技基础设施之一,具备完整的卫星数据接收、传输、存档、处理、分发体系,是我国对地观测领域的核心基础设施之一。地面站的数据接收范围覆盖全国及亚洲的70%疆土。地面站的数据接收系统由天馈伺分系统、跟踪接收分系统、测试分系统、记录与快视分系统、故障诊断分系统、站监控管理分系统、技术支持分系统组成,性能和指标居于世界同类地面站前列。地面站拥有一批国际先进的卫星数据处理与产品生产系统,其产品质量、规格与全球数据产品一致。地面站一系列重要的装置改造和自主创新项目的完成,使卫星数据的接收、处理、存储、检索等系统能力有了显著的提升,可以保证以近实时的速度为用户提供数据产品。地面站运行20余年来,所接收、处理和分发的国内外对地观测卫星数据广泛应用于我国的遥感应用各领域,其中突出的范例有国家重大灾害的监测与评估、全国生态环境质量评价、西部测图、海洋环境近实时监测等国家重大重点项目等。     

Viral satellites: parasitic nucleic acids capable of modulating disease expression

Viral satellites are small nucleic acids that can replicate only in conjunction with the nucleic acids of certain viruses in certain hosts. In spite of the absence of any known nucleotide sequence relationships between a viral satellite, its helper virus, and its host, the trilateral interaction that ensues is usually extremely specific. This specificity is often expressed as a highly characteristic modulation of the disease symptom(s) normally associated with a viral presence in a particular host. This opens up very interesting possibilities for the control of viral plant diseases.     

中国科学院空间科学战略性先导科技专项实施11年回顾与展望

中国科学院空间科学战略性先导科技专项（以下简称“空间科学先导专项”）是中国科学院作为国家战略科技力量主力军,以空间飞行器为平台,瞄准世界科学前沿,从2011年开始布局和实施的前瞻性、战略性重大科技项目。迄今,空间科学先导专项已走过了11年的历程,使我国空间科学的发展第一次有了系统性的支持计划,使我国的空间科学家从旁观者、参与者逐渐走近世界空间科学舞台的中央。文章回顾了空间科学先导专项从实施以来的发展历程,包括专项一期在科学前沿领域和在航天技术领域取得的突破,专项二期正在实施的项目情况,以及正在论证中的空间科学未来规划任务的优选项目。习近平总书记2016年在全国科技创新大会、两院院士大会、中国科协第九次全国代表大会上明确提出,“必须推动空间科学、空间技术、空间应用全面发展”,将发展空间科学放到了我国航天科技发展的首要位置上。展望未来,我们要继续瞄准空间科学领域的重大科技前沿,通过实现“从0到1的突破”,使空间科学在建设中国特色社会主义科技强国的过程中,发挥不可替代的作用。     

The social as the heart of social innovation and social entrepreneurship: An emerging area or an old crossroads?

This paper aims to contribute to the conceptual debate on the connection between social innovation and social entrepreneurship, considering the role of the ‘social’ within this connection. Supported by a systematic literature review (SLR) with an in-depth analysis of 34 articles from Scopus-indexed and Web of Science databases journals, this paper identifies, analyzes and describes the difficulties and opportunities in the social innovation and social entrepreneurship literature. Little is known about the link between both concepts and the influence of the ‘social’ in their development and implementation. This SLR was conducted to identify and describe definitions and patterns. Results show that the connection between social innovation and social entrepreneurship is in its take-off phase, but it still is a fragmented field with a huge lack of consensus. Thus, it will be important to see where the field will head, as this paper aims to be a first step in the understanding of social innovation and social entrepreneurship through a collective and integrated perspective, providing an elucidation of the different perspectives of the literature.     

Continuance intention of online technologies: A systematic literature review

Given the dynamic nature of digital technologies, understanding why users intend to continue to use them or not is important for practitioners and academics alike. This paper presents an up-to-date Systematic Literature Review (SLR) of Continuance Intention (CI) for online technologies. The SLR classifies and analyses 147 relevant articles on CI in the field of online technology. It analyses papers according to the type of online technology as well as four groups of antecedents (psychological, technological, social, and behavioral) of CI and reviews the consequences of CI. Based on the SLR, the paper outlines two broad directions for future research relating to a conceptual framework and research design, highlighting promising research areas linked to the new features of emerging technologies, such as hyper-connectivity, and intention-behavior gaps.     

Telecommunications in rural America: An appraisal and a prediction

Abstract

Rural America has historically been plagued with a disproportionate shortage of health, education, and other public services. However, the application of rapidly changing telecommunications technologies can alleviate many of the problems associated with these isolated and “technologically undernourished” areas. Technologies such as low‐power television, direct broadcast satellites, and satellite‐fed cable services offer the opportunity for building a rural telecommunications network and thus improving services and the quality of life. However, in order for this goal to be realized, the economic constraints presented by insufficient consumer demand and unprofitable markets must be overcome. Direct government subsidization or increased support of projects may be necessary to encourage the private sector to increase investment in telecommunications facilities in rural communities.     

Amateur scientists, the international geophysical year, and the ambitions of Fred Whipple

The contribution of amateur scientists to the International Geophysical Year (IGY) was substantial, especially in the arena of spotting artificial satellites. This article examines how Fred L. Whipple and his colleagues recruited satellite spotters for Moonwatch, a program for amateur scientists initiated by the Smithsonian Astrophysical Observatory (SAO) in 1956. At the same time, however, the administrators with responsibility for the IGY program closely monitored and managed--sometimes even contested--amateur participation. IGY programs like Moonwatch provided valuable scientific information and gave amateurs opportunities to contribute actively to the research of professional scientists. Moonwatch, which operated until 1975, eventually became the public face of a vast satellite-tracking network that expanded the SAO's global reach and helped further Whipple's professional goals. Understanding amateurs' interactions with the professional science community enables us better to understand the IGY as a phenomenon that enlisted broad participation and transcended traditional boundaries between professional and amateur scientists.