Markov chain Monte Carlo methods for high dimensional inversion in remote sensing

Summary.  We discuss the inversion of the gas profiles (ozone, NO₃, NO₂, aerosols and neutral density) in the upper atmosphere from the spectral occultation measurements. The data are produced by the 'Global ozone monitoring of occultation of stars' instrument on board the Envisat satellite that was launched in March 2002. The instrument measures the attenuation of light spectra at various horizontal paths from about 100 km down to 10–20 km. The new feature is that these data allow the inversion of the gas concentration height profiles. A short introduction is given to the present operational data management procedure with examples of the first real data inversion. Several solution options for a more comprehensive statistical inversion are presented. A direct inversion leads to a non-linear model with hundreds of parameters to be estimated. The problem is solved with an adaptive single-step Markov chain Monte Carlo algorithm. Another approach is to divide the problem into several non-linear smaller dimensional problems, to run parallel adaptive Markov chain Monte Carlo chains for them and to solve the gas profiles in repetitive linear steps. The effect of grid size is discussed, and we present how the prior regularization takes the grid size into account in a way that effectively leads to a grid-independent inversion.     

宽带卫星通信和星际链路间激光通信的应用前景

提出了由于信息化社会、Ｉｎｔｅｒｎｅｔ、Ｉｎｔｒａｎｅｔ和多媒体技术的出现,从而要求卫星通信向多体制、多功能发展。文中着重分析了具有独特优点的激光通信在宽带卫星通信和星际链路中的现实商用前景。     

卫星光通信关键技术与演示系统光学天线

针对卫星间光通信链路需求,分析了卫星间激光通信系统关键技术分布。介绍具有自动跟瞄功能的激光通信系统光学天线构成方式,对主要性能参数进行了设计和计算。     

卫星遥感数据法庭可证据性法律问题研究

卫星遥感数据相比传统证据采集方式存在优越性,近些年也频繁地被国际和国内法庭争端当事方用作证据。法庭在是否采信的问题上立场不一,国际法院在涉及领土主权争端案件中对其较为排斥,国际刑事法院、欧盟法院和部分国家国内法院在涉及特定事项时态度较为肯定和积极。原因和卫星遥感数据本身的特质有关,在有着无可比拟优势的同时,其作为证据仍存在个人隐私权保护、知识产权保护、数据的可获得性以及专家证词真实性等问题。卫星遥感数据法庭可证据性问题集中体现了科技与法律之间相互促进和矛盾性,国际社会目前立法仍为空白,国际和地区实践处于分而治之的局面。     

《二十五史》中航海史料标题词表研究

以情报检索语言原理为基础,结合《二十五史》的特点及航海史研究的需要,提出《二十五史》中航海史料标题词表,该词表除可用于对《二十五史》中航海史料进行标引著录并提供检索途径外,还是航海史研究的一个重要工具。     

The Rules of (Dis)engagement: Black Youth and Their Strategies for Navigating Police Contact

Prior work on youth–police relations examines young people's general perceptions of the police, their differential treatment by police officers, and officers' discretion in dealing with youth. Yet researchers have largely neglected the question of how young people attempt to shape these encounters. I address this critical gap, while also incorporating the experiences of “on track” youth and young women—two groups that are not exempt from police contact but traditionally ignored in the youth–police literature. Drawing on semistructured group and individual interviews with 19 black young people in New York City, I investigate the strategies they employ or subscribe to in navigating police contact. Three types of strategies emerged from my analysis: avoidance, management, and symbolic resistance. Avoidance strategies are marked by young people's attempts to preemptively steer clear of officers on the street. Management strategies are employed by young people during police encounters to limit risk or harm, while symbolic resistance is a subtle tactic used by some youth to preserve their dignity in these interactions. This study also considers the gender differences in respondents' approaches and offers new insights into how they assess their police interactions in an era of highly publicized incidents of police brutality.     

基于HHM-RFRM的船舶航行风险评估方法研究

船舶航行风险是由各种风险因素交互作用产生。综合 HHM-RFRM 理论，构建船舶航行多维风险情景危险度测度模型，以风险因素耦合视角探讨船舶航行风险管理问题。在船舶航行多维风险情景危险度测度模型中结合贝叶斯定理，对船舶航行风险情景进行了定性与定量化过滤、评级。最后以大连港某从事商务活动的货船为例，验证了所提出方法的可行性。传统的风险评估方法只能评估单个风险因素对系统的影响，此评估方法克服了这一局限性，为船舶航行风险管理提供新的视角。     

“重陆轻海”与“通洋裕国”之海洋观刍议

明清两朝正处于世界性海洋历史发展的"千古变局"时代,但统治者沿袭传统模式,在立国思想上"重农抑商"、"重陆轻海",在国防战略上以"禁海"代替海防,禁海迁界、"守土防御",反映其海洋观念的淡薄;而东南沿海地方官员,尤其郑成功"通洋裕国"思想的提出和实践,显露出"以商立国",向海洋空间发展的意涵;传统时代"重陆轻海"与"通洋裕国"所反映的海洋观念,对国家民族发展的影响在某种程度上可以忽略不计,但大航海时代,海洋作为人类的第二生存空间影响到世界历史走向和发展格局时,"重陆轻海"观念所带来的深层影响会因此而改变国家和民族的命运。     

Navigating the migration industry: migrants moving through an African-European web of facilitation/control

ABSTRACT

This paper approaches the African-European migration industry as a complex web of relations in which different actors liaise, objectives oppose each other, and roles overlap. Starting from this notion, the question emerges: How do migrants navigate this fuzzy web of migration facilitation/control? To answer this question, this paper uses a ‘trajectory ethnography’ that follows the im/mobility processes of migrants from West – and Central Africa to, and inside, Europe. In so doing, it particularly focuses on two practices that are related to the concept of social navigation. First, it concerns débrouillardise, a term that points to the power of improvisation, creativity and hustling. Second, it regards social negotiation, a term referring to the process of how migrants ‘massage’ their relations with important actors in the field. The findings stress the relational dimension of the migration industry in the sense that the functioning of one actor depends so much on the intentions and efforts of others. I conclude that we could enhance our knowledge on migration industries with studies that constantly shift between the perspective of the migrant, the social network, the facilitator and controller. Such a dynamic approach unpacks further the multiple efforts that produce migrant im/mobility.     

Television and the making of a transnational Alevi identity

ABSTRACT

Satellite broadcasting technologies contribute a great deal to interaction across national boundaries, and in this regard satellite television is significant in the construction of a transnational public sphere for the Alevi community in Turkey and abroad. This paper addresses the role of television in the making of that transnational Alevi identity. In particular, it focuses on the flow and the programme contents of Cem TV and Yol TV, two leading Alevi channels, to demonstrate how the transnational imagination of Alevi identity corresponds to different political understandings of Aleviness.