Large scale multiple robot visual mapping with heterogeneous landmarks in semi-structured terrain

This paper addresses the cooperative localization and visual mapping problem with multiple heterogeneous robots. The approach is designed to deal with the challenging large semi-structured outdoors environments in which aerial/ground ensembles are to evolve. We propose the use of heterogeneous visual landmarks, points and line segments, to achieve effective cooperation in such environments. A large-scale SLAM algorithm is generalized to handle multiple robots, in which a global graph maintains the relative relationships between a series of local sub-maps built by the different robots. The key issue when dealing with multiple robots is to find the link between them, and to integrate these relations to maintain the overall geometric consistency; the events that introduce these links on the global graph are described in detail. Monocular cameras are considered as the primary extereoceptive sensor. In order to achieve the undelayed initialization required by the bearing-only observations, the well-known inverse-depth parametrization is adopted to estimate 3D points. Similarly, to estimate 3D line segments, we present a novel parametrization based on anchored Plücker coordinates, to which extensible endpoints are added. Extensive simulations show the proposed developments, and the overall approach is illustrated using real-data taken with a helicopter and a ground rover.     

基于高精度导航设备的海上多传感器配准算法

对海上多平台多传感器误差配准问题,利用平台的高精度导航信息将各传感器的量测数据转换到地心坐标系下,构建关于传感器偏差和舰艇姿态误差的伪测量模型,采用卡尔曼滤波对配准误差进行在线估计和补偿.算法较好地解决了传统的基于球极投影误差配准技术受地球曲率影响的不足,并突破了离线配准算法假定配准误差恒定的限制.仿真实验结果验证了算法的正确性和有效性.     

基于机制设计理论的自组网节点合作协议

在移动自组网中,如何激励自私节点,使之参与网络合作,是当前研究的热点问题.文中提出了LMOCP协议,采用VCG机制计算转发节点的支付.通过引入邻居发现机制,并改进路由发现过程,使网络中控制消息的数量从O(n3)减少到O(n2).对协议的正确性进行了分析,并证明了LMOCP协议是事后纳什可实施的,在所有节点都是理性的这一共同知识的假定下,每个节点的最优策略是诚实地报告自己的转发价格.通过ms-2对协议进行了验证,仿真结果显示,与现有的几种重要协议相比,LMOCP协议具有更低的消息负载和网络延迟.     

Research on the application of 4-weighted fractional Fourier transform in communication system

The paper reveals the relationship between the weighting coefficients and weighted functions via the research of coefficients matrix and based on the original definition of 4-weighted fractional Fourier transform(4-WFRFT).The multi-parameters expression of weighting coefficients are given.Moreover, the 4-WFRFT of discrete sequences is defined by introducing DFT into it, which makes it suitable for digital communication systems.After analyzing the properties of WFRFT, a typical scheme for modulation/demodula...     

地球观测领域国际科技合作现状、趋势及启示

应对全球气候变化对人类社会生存带来的影响是全世界的共同责任。进一步认识地球、关注地球发展规律,保护人类共同家园已成为世界各国政府的共识。共同发展地球观测技术,提高对地观测能力成为新世纪世界各国的共同要求,因此,地球观测领域国际科技合作成为进入21世纪以来国际科技合作的主流。建立该领域有效的国际科技合作机制,了解国际对地观测的最新技术和相关活动,及时制定和调整我国的相关工作计划,为我国该观测领域发展提供重要的依据,已成为迫在眉睫的工作。本文在介绍地球观测领域国际合作发展现状基础上,通过分析地球观测领域发展趋势,提出发展我国地球观测领域国际科技合作的建议。     

基于卡尔曼过滤的多传感器协作数据重构算法研究

本文针对多传感器系统存在的数据易丢失、易受干扰和易失真等问题,在卡尔曼过滤的基础上结合协同合作方式提出了一种协作数据重构算法。该算法从一阶线性化、二次加权突变平滑和随机统计特征等方面出发建立了适用于多传感器系统的卡尔曼过滤算法,然后基于中继转发信号和自适应感知时间间隙,给出了协作数据重构多传感器系统协同过程控制算法。数学分析和实验结果表明,所提算法与压缩感知重构算法相比在监测数据准确度、均方差、功耗和能耗等方面表现出优势。     

Collaborative distribution between two logistics service providers

Mathematical models are described for collaborative distribution between two logistics service providers (LSPs). We find that (a) collaborative distribution is conditionally profitable for LSPs, and the conditions for cooperation are given; (b) LSPs save more costs primarily by shortening the delivery distance and decreasing delivery speed; (c) collaborative distribution makes the delivery time either shorter or longer; (d) if one LSP changes its equilibrium price, the total profit conditionally increases, and this condition is related to demand structure and delivery cost structure; and (e) collaborative distribution can solve the personalization of delivery time and reduce pollution to some extent. For the companies sharing the incremental profit, we characterize a transfer payment contract that includes fixed and variable fees. Our findings suggest that LSPs should adopt collaborative distribution to formulate an optimal distribution plan to save costs and shorten the delivery time, and should select partners with smaller cost parameters and both different and moderate speeds. In addition, warehouse and vehicle sharing are beneficial to the implementation of collaborative distribution.     

ABAC策略语义表示和决策方法

为解决开放式系统环境中基于属性的访问控制（Attribute—Based Access Control,ABAC）策略语义层次上的表示和决策问题,提出了ABAC策略的本体表示方法。该方法基于ABAC策略模型到描述逻辑定义的映射,使用语义Web规则语言（swRL）处理系统内部关系定义。在此基础上,提出了基于封闭世界和实例实现推理的策略决策框架。最后从可靠性和完备性两方面说明了决策方法的正确性,验证实验表明了方法在实际应用中的适用性。     

Parallel characterizations of a generalized Shapley value and a generalized Banzhaf value for cooperative games with level structure of cooperation

We present parallel characterizations of two different values in the framework of restricted cooperation games. The restrictions are introduced as a finite sequence of partitions defined on the player set, each of them being coarser than the previous one, hence forming a structure of different levels of a priori unions. On the one hand, we consider a value first introduced in Ref. [18], which extends the Shapley value to games with different levels of a priori unions. On the other hand, we introduce another solution for the same type of games, which extends the Banzhaf value in the same manner. We characterize these two values using logically comparable properties.     

域间路由协同监测中的信息共享机制

路由协同监测通过在自治系统之间共享路由监测信息来形成更为完整的全局监测视图,从而克服域间路由系统自治性的制约,提高单个自治系统的路由监测能力.针对路由协同监测的核心问题——监测信息共享,基于自组织思想设计了信息共享机制CoISM.该机制利用BGP路由策略引起的信息局部性对路由监测信息的传播范围进行裁减和控制,在被动查询的基础上增加了信息"反射"行为,利用路由监测信息之间的相关性实现信息的主动推送,将自治系统的利益建立在主动信息共享这一利他行为的基础上.CoISM能够引导自治系统实现路由监测信息的自组织聚合与按需共享,具有激励性,能够促进自治系统之间的协同.该机制采用分布式体系结构,具有良好的扩展性和较低的通信开销,不需要修改BGP协议,支持可渐进部署,适用于域间路由协同监测、路由故障协同分析、协同入侵检测等多种跨域协同管理应用.