Nonlinear Filtering With Sample-Based Approximation Under Constrained Communication:Progress, Insights and Trends

The nonlinear filtering problem has enduringly been an active research topic in both academia and industry due to its ever-growing theoretical importance and practical significance.The main objective of nonlinear filtering is to infer the states of a nonlinear dynamical system of interest based on the available noisy measurements. In recent years, the advance of network communication technology has not only popularized the networked systems with apparent advantages in terms of installation,cost and maintenance, but also brought about a series of challenges to the design of nonlinear filtering algorithms, among which the communication constraint has been recognized as a dominating concern. In this context, a great number of investigations have been launched towards the networked nonlinear filtering problem with communication constraints, and many samplebased nonlinear filters have been developed to deal with the highly nonlinear and/or non-Gaussian scenarios. The aim of this paper is to provide a timely survey about the recent advances on the sample-based networked nonlinear filtering problem from the perspective of communication constraints. More specifically, we first review three important families of sample-based filtering methods known as the unscented Kalman filter, particle filter,and maximum correntropy filter. Then, the latest developments are surveyed with stress on the topics regarding incomplete/imperfect information, limited resources and cyber security.Finally, several challenges and open problems are highlighted to shed some lights on the possible trends of future research in this realm.

Experimental study of water curtain performance for gas storage in an underground cavern

An artificial water curtain system is composed of a network of underground galleries and horizontal boreholes drilled from these galleries.Pre-grouting measures are introduced to keep the bedrock saturated all the time.This system is deployed over an artificial or natural underground cavern used for the storage of gas（or some other fluids） to prevent the gas from escaping through leakage paths in the rock mass.An experimental physical modeling system has been constructed to evaluate the performance of artificial water curtain systems under various conditions.These conditions include different spacings of caverns and cavern radii located below the natural groundwater level.The principles of the experiment,devices,design of the physical model,calculation of gas leakage,and evaluation of the critical gas pressure are presented in this paper.Experimental result shows that gas leakage is strongly affected by the spacing of water curtain boreholes,the critical gas pressure,and the number and proximity of storage caverns.The hydraulic connection between boreholes is observed to vary with depth or location,which suggests that the distribution of water-conducting joint sets along the boreholes is also variable.When designing the drainage system for a cavern,drainage holes should be orientated to maximize the frequency at which they encounter major joint sets and permeable intervals studying in order to maintain the seal on the cavern through water pressure.Our experimental results provide a significant contribution to the theoretical controls on water curtains,and they can be used to guide the design and construction of practical storage caverns.

Design and operation problems related to water curtain system forunderground water-sealed oil storage caverns

The underground water-sealed storage technique is critically important and generally accepted for the national energy strategy in China. Although several small underground water-sealed oil storage caverns have been built in China since the 1970s, there is still a lack of experience for large-volume underground storage in complicated geological conditions. The current design concept of water curtain system and the technical instruction for system operation have limitations in maintaining the stability of surrounding rock mass during the construction of the main storage caverns, as well as the long-term stability. Although several large-scale underground oil storage projects are under construction at present in China, the design concepts and construction methods, especially for the water curtain system, are mainly based on the ideal porosity medium flow theory and the experiences gained from the similar projects overseas. The storage projects currently constructed in China have the specific features such as huge scale, large depth, multiple-level arrangement, high seepage pressure, complicated geological conditions, and high in situ stresses, which are the challenging issues for the stability of the storage caverns. Based on years’ experiences obtained from the first large-scale （millions of cubic meters） underground water-sealed oil storage project in China, some design and operation problems related to water curtain system during project construction are discussed. The drawbacks and merits of the water curtain system are also presented. As an example, the conventional concept of “filling joints with water” is widely used in many cases, as a basic concept for the design of the water curtain system, but it is immature. In this paper, the advantages and disadvantages of the conventional concept are pointed out, with respect to the long-term stability as well as the safety of construction of storage caverns. Finally, new concepts and principles for design and construction of the underground water-sealed oil storage caverns are proposed.

Profiling gene expression patterns of nasopharyngeal carcinoma and normal nasopharynx tissues with cDNA microarray

5 μg of total RNAs from normal nasopharynx and nasopharyngeal carcinoma tissue have been labeled with α-32P-dCTP during reverse transcription. The synthesized cDNA probes have been hybridized to high-density cDNA microarray containing 5184 genes or expression sequence tags (ESTs). Then image analysis software has been applied to comparing their expression profiles. Results show that 187 ESTs were of density value above 200 in nasopharyngeal carcinoma tissue while there were 307 such ESTs in normal nasopharynx tissue; 38 ESTs were strongly expressed in nasopharynx, but weakly expressed in nasopharyngeal carcinoma; 48 ESTs were strongly expressed in nasopharyngeal carcinoma, but weakly expressed in normal nasopharynx. These results suggest that there may exist some new differentially expressed genes involved in nasopharyngeal carcinoma development. Furthermore, the results strongly indicate that high-density cDNA microarray is a powerful and efficient tool for large-scale screening differentially

Fast and Adaptive Multi-Agent Planning under Collaborative Temporal Logic Tasks via Poset Products

Efficient coordination and planning is essential for large-scale multi-agent systems that collaborate in a shared dynamic environment. Heuristic search methods or learning-based approaches often lack the guarantee on correctness and performance. Moreover, when the collaborative tasks contain both spatial and temporal requirements, e.g., as linear temporal logic (LTL) formulas, formal methods provide a verifiable framework for task planning. However, since the planning complexity grows exponentially with the number of agents and the length of the task formula, existing studies are mostly limited to small artificial cases. To address this issue, a new planning paradigm is proposed in this work for system-wide temporal task formulas that are released online and continually. It avoids two common bottlenecks in the traditional methods, i.e., (a) the direct translation of the complete task formula to the associated B點hi automaton and (b) the synchronized product between the B點hi automaton and the transition models of all agents. Instead, an adaptive planning algorithm is proposed, which computes the product of relaxed partially ordered sets (R-posets) on-the-fly and assigns these subtasks to the agents subject to the ordering constraints. It is shown that the first valid plan can be derived with a polynomial time and memory complexity with respect to the system size and the formula length. Our method can take into account task formulas with a length of more than 400 and a fleet with more than 400 agents, while most existing methods fail at the formula length of 25 within a reasonable duration. The proposed method is validated on large fleets of service robots in both simulation and hardware experiments.

基于动作链的形式化任务协同规划

基于形式化方法的多智能体任务规划因其丰富的任务形式和多样的系统功能而备受关注.然而,随着智能体数量增加,规划复杂度呈指数级增长,因此形式化方法在计算效率和集群规模上都受到了限制.已有的改良方法中,基于图搜索的方法对计算效率改进有限,只能处理中等规模的集群;而基于组合优化的算法忽略了智能体动作模型,无法处理大规模协同任务.本文针对以上局限,提出了基于智能体动作链的偏序任务分配算法,在保证正确性的基础上大幅提升规划性能.进一步针对环境不确定性和在线新任务,设计了自适应重规划算法和协作同步机制,确保任务执行过程中的鲁棒性.最后,通过数值仿真和对比验证了算法的有效性和可靠性.

生态产品价值实现:国际经验

生态产品价值实现是解决生态效益外部性问题,实现生态保护与经济社会协调发展的重要途径,已成为社会各界高度关注的焦点问题之一。部分发达国家较早认识到生态保护与经济社会协调发展的重要性,率先开展了许多制度性改革,并在实践中取得了显著成效,形成了政府与市场并重的生态产品价值实现模式。基于此,文中通过分析美国、新西兰、日本3国分别在生态保护修复、生态权属交易和生态产业化发展方面的生态产品价值实现典型案例,归纳得出可供借鉴的5点经验,提出对我国全面建立生态产品价值实现机制的4点启示。

Consensus disturbance rejection control of directed multi-agent networks with extended state observer

This paper investigates the consensus disturbance rejection problem among multiple high-order agents with directed graphs.Based on disturbance observers,distributed consensus disturbance rejection protocols are constructed in leaderless and leader-follower consensus setups.Different from the previous related papers,the consensus protocols in this paper are developed in a fully distributed fashion,relying on only the state information of each agent and its neighbors.Sufficient conditions are provided to guarantee that the asymptotic stability of high-order multi-agent systems can be reached with matched disturbances.