DILIGENT: integrating digital library and Grid technologies for a new Earth observation research infrastructure

This paper introduces DILIGENT, a digital library infrastructure built by integrating digital library and Grid technologies and resources. This infrastructure allows different communities to dynamically build specialised digital libraries capable to support the entire e-Science knowledge production and consumption life-cycle by using shared computing, storage, content, and application resources. The paper presents some of the main software services that implement the DILIGENT system. Moreover, it exemplifies the provided features by presenting how the DILIGENT infrastructure is being exploited in supporting the activity of user communities working in the Earth Science Environmental sector. This work is partially funded by the European Commission in the context of the DILIGENT project, under the 2nd call of FP6 IST priority.     

利用四元数实现三维地球场景的漫游

场景的交互性操作是地球三维可视化的重要研究内容。尽管人们通过直接滤波欧拉角来平滑方位数据,但是平滑欧拉角未必会产生平滑的运动,这是由旋转群和欧氏空间之间的度量单位的差异引起的。Hamilton于1853年发现的四元数提供了描述旋转的途径。文章首先讨论了四元数的一般原理籍优越性;接着论述了三维虚拟地球的建模方法,采用四元数技术实现了三维地球的任意旋转的问题;最后在数字地球原型系统上进行了实验研究,实验证明四元数技术是提供一种解决大规模地形场景实时漫游的有效途径。     

A relevant course in statistics,research and policy development

Many students with master's degrees who enter fields where policy-making and management are intertwined lack the ability to direct or use supporting research based on computerized quantitative techniques. We have developed a first year graduate course which gives students experience with a real, often controversial, research problem. These students, who come largely from non-numerical backgrounds, become capable of communicating effectively with programmers and of evaluating statistical research by others, so that upon graduation they are much more capable of doing relatively sophisticated, computerized research on their own.     

Daily imaging scheduling of an Earth observation satellite

This work presents the development of a daily imaging scheduling system for a low-orbit, Earth observation satellite. The daily imaging scheduling problem of satellite considers various imaging requests with different reward opportunities, changeover efforts between two consecutive imaging tasks, cloud-coverage effects, and the availability of the spacecraft resource. It belongs to a class of single-machine scheduling problems with salient features of sequence-dependent setup, job assembly, and the constraint of operating time windows. The scheduling problem is formulated as an integer-programming problem, which is NP-hard in computational complexity. Lagrangian relaxation and linear search techniques are adopted to solve this problem. In order to demonstrate the efficiency and effectiveness of our solution methodology, a Tabu search-based algorithm is implemented, which is modified from the algorithm in Vasquez and Hao, 2001. Numerical results indicate that the approach is very effective to generate a near-optimal, feasible schedule for the imaging operations of the satellite. It is efficient in applications to the real problems. The Lagrangian-relaxation approach is superior to the Tabu search one in both optimality and computation time.     

Earth observation modeling based on layer scattering matrices

The differential equations describing radiative transfer in vegetative canopies as given by Suits are generalized and solved to derive a layer scattering matrices. Layer scattering matrices can be applied to the calculation of optical parameters for multilayer ensembles according to the Adding method. The application to atmospheric scattering is demonstrated by explaining path radiance, sky radiance, and other quantities in terms of elements from a layer scattering matrix and a surface reflectance matrix. By combining scattering matrices originating from atmospheric layers with those from earth objects, earth observation models can be constructed. These may become valuable tools in the study of various remote sensing problems.     

The landscape of Blockchain research: impacts and opportunities

Blockchain technology has emerged as an important research domain in recent years. It not only supports the secure and efficient storage and processing of information but may also transform the business principles and processes embedded in traditional centralized organizations and societies. This editorial first provides a framework that identifies the emerging areas of blockchain research. The key characteristics of this framework in Blockchain 1.0, 2.0, and 3.0 are defined and introduced. The impacts and opportunities associated with blockchain research are identified and discussed. At last, the six articles in this special issue are characterized using the proposed research framework of blockchain research.

     

Landscape generator: Method to generate landscape configurations for spatial plan-making

Current spatial planning tools focus mainly on land use evaluation and not on spatial plan design. Automated generation of spatial design intends to bridge the gap between graphical design and geographical information systems. We propose a new method that generates spatial plans with a high level of detail and realism. A simple set of rules is derived by the modeler from a landscape type that serves as a reference. These rules are implemented by spatial functions with a landscape type specific objective. In a multi-objective optimization algorithm a landscape plan is generated for a specific lot that meets the objectives. The modeler controls the plan generation process through an objective task list which determines the priority of the objectives. Examples show that the landscape generator is capable of generating plausible spatial plans in reasonable computing time. More specifically, they show that the landscape generator performs best with low configurationally structured reference projects and performs less with high configurationally structured reference projects. The manual construction of the objective task list could be further improved by pre-structured objectives dependent on landscape designer’s preference.     

Earth observation satellite sensors for biodiversity monitoring: potentials and bottlenecks

Many biologists, ecologists, and conservationists are interested in the possibilities that remote sensing offers for their daily work and study site analyses as well as for the assessment of biodiversity. However, due to differing technical backgrounds and languages, cross-sectorial communication between this group and remote-sensing scientists is often hampered. Hardly any really comprehensive studies exist that are directed towards the conservation community and provide a solid overview of available Earth observation sensors and their different characteristics. This article presents, categorizes, and discusses what spaceborne remote sensing has contributed to the study of animal and vegetation biodiversity, which different types of variables of value for the biodiversity community can be derived from remote-sensing data, and which types of spaceborne sensor data are available for which time spans, and at which spatial and temporal resolution. We categorize all current and important past sensors with respect to application fields relevant for biologists, ecologists, and conservationists. Furthermore, sensor gaps and current challenges for Earth observation with respect to data access and provision are presented.     

一种灵活的访问控制策略及其应用研究*

提出了一种声明式的、面向对象的、灵活访问控制策略的形式化描述、决策算法和实施框架。与传统访问控制策略相比,它包含授权类型、主体、权限、限制、影响等策略元素,能够更加精确地描述各类控制需求;同时,提出的策略决策算法和实施框架能适应决策环境的动态变化,有效满足复杂分布式系统的访问控制需求;最后,作为应用的例子,介绍了这种策略和实施框架在分布式园区网中的实现和应用情况。     

云计算平台安全策略研究

云计算平台信息的安全保护策略是云计算时代不得不面对的问题.本文从数据安全为题、虚拟化技术存在的隐患、云平台系统可靠性等云平台面临的安全问题入手,详细阐述了云平台的信息安全保护策略,包括云平台的搭建、数据加密和数据隔离的数据保护策略以及加强网络数据过滤和传送机制的网络安全策略,从而确保云平台的数据信息的安全.     

政策描述规范的研究综述*

国内外政策描述规范方面的研究,主要有四个流派：KAoS、Rei、Ponder和PRAL。首先对这几个流派进行了详细的介绍,利用举例的方式阐述它们政策的表示方法、政策类型,同时概括介绍了它们的政策冲突发现和解决方法。按照政策表达、政策类型、政策冲突解决和政策的制定工具这几个角度对四个流派进行分析和比较,指出它们各自的优势与不足。最后,总结分析了当前研究的特点和不足,指出了未来的研究方向。     

A bibliometric perspective of learning analytics research landscape

ABSTRACT

Learning analytics is an emerging field of research, motivated by the wide spectrum of the available educational information that can be analysed to provide a data-driven decision about various learning problems. This study intends to examine the research landscape of learning analytics to deliver a comprehensive understanding of the research activities in this multidisciplinary field, using scientific literature from the Scopus database. An array of state-of-the-art bibliometric indices is deployed on 2811 procured publication datasets: publication counts, citation counts, co-authorship patterns, citation networks and term co-occurrence. The results indicate that the field of learning analytics appears to have been instantiated around 2011; thus, before this time period no significant research activity can be observed. The temporal evolution indicates that the terms ‘students’, ‘teachers’, ‘higher education institutions’ and ‘learning process’ appear to be the major components of the field. More recent trends in the field are the tools that tap into Big Data analytics and data mining techniques for more rational data-driven decision-making services. A future direction research depicts a need to integrate learning analytics research with multidisciplinary smart education and smart library services. The vision towards smart city research requires a meta-level of smart learning analytics value integration and policy-making.     

The cyber threat landscape: Challenges and future research directions

Cyber threats are becoming more sophisticated with the blending of once distinct types of attack into more damaging forms. Increased variety and volume of attacks is inevitable given the desire of financially and criminally-motivated actors to obtain personal and confidential information, as highlighted in this paper. We describe how the Routine Activity Theory can be applied to mitigate these risks by reducing the opportunities for cyber crime to occur, making cyber crime more difficult to commit and by increasing the risks of detection and punishment associated with committing cyber crime. Potential research questions are also identified.     

The Singapore experience: Synergy of national policy, classroom practice and design research

In recent years there has been a proliferation of research findings on CSCL at the micro and macro levels, but few compelling examples of how CSCL research has impacted actual classroom practices at the meso-level have emerged. This paper critically examines the impact of adopting a systemic approach to innovative education reforms at the macro, meso, and micro levels in Singapore. It presents the case for adopting design research as a methodology for CSCL integration that meets the needs of schools, and discusses a specific CSCL innovation that holds the potential for sustaining transformation in classroom practices. Our driving question is: In what ways can the routine use of CSCL practices in the classroom be supported by exploring systemic factors in the school setting through design research? We will explore the synergistic conditions that led to meaningful impact (at the micro level), mediated by systemic approaches to working with teachers in the schools (at the meso level), guided by Singapore’s strategic planning for scalability (at the macro level).     

可重用策略服务器框架的研究和实现

框架是应用系统的可重用设计,通过重用框架的架构和代码,可以降低系统的开发成本。以Avalon应用框架为基础,利用一些相互联系的设计模式,设计了一个通用的策略服务器框架（policy server framework,PSF）,并通过一个简单的EchoServer服务验证了PSF的有效性。在实际项目中通过应用PSF,不仅缩短了开发周期,而且获得了很高的复用收益率。     

基于审计与访问控制的授权策略研究

对于基于角色的访问控制（RBAC）已经出现大量的研究,作为特权管理设施（PMI）的另一种解决方案基于策略服务器的研究甚少,难点之一是策略协议设计与策略授权管理过于复杂。设计身份认证（CA）策略和授权策略协议,提出了一种新的策略授权模型对数据业务系统进行访问控制和审计。达到了数据的内部安全目的,为PMI参考模型提供研究动力。     

Testing and validation of cloud infrastructures for Earth observation services with satellite constellations

Earth observation (EO) with satellites has been applied in different fields such as environment monitoring, natural disasters response, emergencies management, civil security, intelligence, maritime surveillance, and many others. Some of the application fields are very demanding in terms of system revisit time and product delivery time. This is the case of responses to natural disasters.

However EO still presents critical challenges to overcome in order to cover the actual demand of services: (i) high revisit time, (ii) high response time, and (iii) easy and instant access to EO products. To increase the revisit time and broaden the applications of the remote sensing, new space concepts such as constellations and formations of satellites have been developed. However, the traditional ground infrastructures, which are required to process and store data, are expensive. Moreover, their limited scalability as well as their limited flexibility to manage large and variable amounts of imagery data shall also be considered.

Along this work, we propose a cloud infrastructure for data management to be validated with a constellation of 17 satellites acquiring the Earth’s surface on a daily basis in order to offer high added value services for highly demanding applications. The satellites download the raw data images in a network of 12 ground stations distributed around the world to provide global coverage. The cloud system is based on previous works carried out by the research group. Thus the cloud infrastructure is tested and evaluated for its use in the EO sector and applied to different realistic scenarios, including an intensive comparison with a traditional system responding to the Lorca’s earthquake, which occurred in Spain in 2011.     

IPsec体系结构及其策略管理机制的研究

随着网络安全性的要求越来越高,IPsec已经成为Internet安全体系结构的基石,如果得到正确的实现,IPsec对那些不支持它的主机和网络不会产生负面影响。本文首先对IPsec的体系结构进行了描述和分析,然后针对目前通信中存在的不足对策略管理部分进行研究,并以Windows2000为环境探讨了基于SPS的IPSec策略管理机制。     

Experiences in building a Grid-based platform to serve Earth observation training activities

Earth observation data processing and storing can be done nowadays only using distributed systems. Experiments dealing with a large amount of data are possible within the timeframe of a lesson and can give trainees the freedom to innovate. Following these trends and ideas, we have built a proof-of-the-concept platform, named GiSHEO, for Earth observation educational tasks. It uses Grid computing technologies to analyze and store remote sensing data, and combines them with eLearning facilities. This paper provides an overview of the GiSHEO's platform architecture and of its technical and innovative solutions.