Synchronized output regulation of switching networks based on synchronization observer

This paper studies the synchronized output regulation (SOR) problem of networked dynamic systems with switching topology that is uniformly connected and leader-rooted. In these networked systems, the tracked signal or the rejected disturbance is generated by the same exosystem, and however, the state of the exosystem is only available for leader nodes. First, a synchronization observer of the exosystem is proposed in this paper to overcome the difficulty caused by the unavailable state of the exosystem for follower nodes with directed switching information flow. It is shown that the observer state will synchronize to the state of the exosystem. Then, two feedback controllers based on decentralized dynamic error and state are presented to solve this SOR problem. Furthermore, the main idea in this paper will provide a promising way for realizing the multirobot systems’ tracking and formation requirement. Numerical simulation results are presented to demonstrate the effectiveness of the theoretical results.     

基于Crossbar交换结构的虚输出队列研究

交换结构及队列调度算法是影响交换机性能的主要因素。此文对基于C rossbar结构的虚输出队列（VOQ）模型从交换结构、 排列模型、实现原理、吞吐率和调度算法方面进行了分析和研究，为构造高带宽的交换机提供了有意义的结论。     

Controller performance assessment based on minimum and open-loop output variance

The need to achieve reliable and effective automatic control systems has directed numerous research efforts towards the development of monitoring and assessment methods of the closed-loop performance. A new controller assessment index, called relative variance index (RVI) is introduced in this work, according to which the closed-loop performance is compared with the best theoretical control action (minimum variance control) and no control action. For the estimation of RVI, an identification method is employed to extract the system models and an estimate of the process unit delays. The proposed index, RVI, is in agreement with the classical deterministic closed-loop assessment measures and thus can be utilized for the controller performance evaluation more effectively.     

Reversible watermarking method based on asymmetric-histogram shifting of prediction errors

This paper tries to provide a new perspective for the research of reversible watermarking based on histogram shifting of prediction errors. Instead of obtaining one prediction error for the current pixel, we calculate multiple prediction errors by designing a multi-prediction scheme. An asymmetric error histogram is then constructed by selecting the suitable one from these errors. Compared with traditional symmetric histogram, the asymmetric error histogram reduces the amount of shifted pixels, thus improving the watermarked image quality. Moreover, a complementary embedding strategy is proposed by combining the maximum and minimum error histograms. As the two error histograms shift in the opposite directions during the embedding, some watermarked pixels will be restored to their original values, thus the image quality is further improved. Experimental findings also show that the proposed method re-creates watermarked images of higher quality that carry larger embedding capacity compared to conventional symmetric histogram methods, such as Tsai et al.’s and Luo et al.’s works.     

Controller design for consensus of non-uniform rank systems with switching topology and relative output measurements

This paper studies the design problem of a controller to achieve an asymptotic consensus for a class of non-uniform rank linear systems. The interconnection topology for the N non-uniform rank systems is assumed to be modeled by a time-varying graph that switches in a finite set of connected and undirected graphs and has a non-vanishing dwell time. Under these conditions, we propose a controller for the asymptotic consensus of the N systems and provide a closed formula for an agreed trajectory that in fact indicates the attainment of average consensus. The controller is implemented through the backstepping and high-gain observer techniques, and uses only relative output measurements from the neighboring systems for the purpose of feedback. The idea behind this implementation is that the output feedback controller implemented in this way can make the norm of the state of the closed-loop system arbitrary small within any given dwell time, even for non-uniform rank systems.     

基于输出误差模型优化的甲板运动预报算法研究

本文提出了一种适用于多种复杂海况的大型舰船甲板运动预报方法,目的在于提高算法对不同海域复杂海况的适用性,以及对甲板运动模型的辨识精度与预报精度。该方法通过将量测数据的时间滞后处理引入输出误差模型来描述甲板运动的动力学模型,引入定阶准则确定了模型最优阶数数对。在此基础上应用了辅助模型递推最小二乘算法进行系统参数辨识并估计输出误差模型中的状态变量。实验结果表明,本文所提出的预报方法在系统参数辨识阶段可以将递推最小二乘算法的辨识精度提高5.13%,并且在预报阶段可以有效地将甲板运动的幅值与相位预测精度提高3.17%。该方法在复杂海况下具备良好的预测性能,适用于大型舰船甲板运动预报。     

可预测期望航向的船舶航迹控制器设计

为了提高航迹控制器的跟踪性能,节省航程,本文推导了期望航向和航迹偏差的数学模型,设计了可预测期望航向的船舶航迹预测控制器,它不仅能预测系统的输出(船首向和航迹偏差),而且可以提前多步预测系统的参考输入(期望航向),以提前修正命令舵角.对货船的航迹控制计算机仿真结果表明,算法提高了控制器的跟踪速度和精度,缩短了船舶的实际航程.本文还给出了求解控制器中逆矩阵的递推算法,其计算量为通常算法的1/3.     

Subjectively adapted high capacity lossless image data hiding based on prediction errors

This article reports on a lossless data hiding scheme for digital images where the data hiding capacity is either determined by minimum acceptable subjective quality or by the demanded capacity. In the proposed method data is hidden within the image prediction errors, where the most well-known prediction algorithms such as the median edge detector (MED), gradient adjacent prediction (GAP) and Jiang prediction are tested for this purpose. In this method, first the histogram of the prediction errors of images are computed and then based on the required capacity or desired image quality, the prediction error values of frequencies larger than this capacity are shifted. The empty space created by such a shift is used for embedding the data. Experimental results show distinct superiority of the image prediction error histogram over the conventional image histogram itself, due to much narrower spectrum of the former over the latter. We have also devised an adaptive method for hiding data, where subjective quality is traded for data hiding capacity. Here the positive and negative error values are chosen such that the sum of their frequencies on the histogram is just above the given capacity or above a certain quality.     

Algorithmic complexity bounds on future prediction errors

We bound the future loss when predicting any (computably) stochastic sequence online. Solomonoff finitely bounded the total deviation of his universal predictor M from the true distribution μ by the algorithmic complexity of μ. Here we assume that we are at a time t > 1 and have already observed x = x₁ ⋯ x_t. We bound the future prediction performance on x_t+1x_t+2 ⋯ by a new variant of algorithmic complexity of μ given x, plus the complexity of the randomness deficiency of x. The new complexity is monotone in its condition in the sense that this complexity can only decrease if the condition is prolonged. We also briefly discuss potential generalizations to Bayesian model classes and to classification problems.     

IFCS: an intelligent fast channel switching in IPTV over PON based on human behavior prediction

In this work we are concerned with detecting non-collaborative videos in video sharing social networks. Specifically, we investigate how much visual content-based analysis can aid in detecting ballot stuffing and spam videos in threads of video responses. That is a very challenging task, because of the high-level semantic concepts involved; of the assorted nature of social networks, preventing the use of constrained a priori information; and, which is paramount, of the context-dependent nature of non-collaborative videos. Content filtering for social networks is an increasingly demanded task: due to their popularity, the number of abuses also tends to increase, annoying the user and disrupting their services. We propose two approaches, each one better adapted to a specific non-collaborative action: ballot stuffing, which tries to inflate the popularity of a given video by giving “fake” responses to it, and spamming, which tries to insert a non-related video as a response in popular videos. We endorse the use of low-level features combined into higher-level features representation, like bag-of-visual-features and latent semantic analysis. Our experiments show the feasibility of the proposed approaches.     

Bootstrap prediction mean squared errors of unobserved states based on the Kalman filter with estimated parameters

In the context of linear state space models with known parameters, the Kalman filter (KF) generates best linear unbiased predictions of the underlying states together with their corresponding Prediction Mean Square Errors (PMSE). However, in practice, when the filter is run with the parameters substituted by consistent estimates, the corresponding PMSE do not take into account the parameter uncertainty. Consequently, they underestimate their true counterparts. In this paper, we propose two new bootstrap procedures to obtain PMSE of the unobserved states designed to incorporate this latter uncertainty. We show that the new bootstrap procedures have better finite sample properties than bootstrap alternatives and than procedures based on the asymptotic approximation of the parameter distribution. The proposed procedures are implemented for estimating the PMSE of several key unobservable US macroeconomic variables as the output gap, the Non-accelerating Inflation Rate of Unemployment (NAIRU), the long-run investment rate and the core inflation. We show that taking into account the parameter uncertainty may change their prediction intervals and, consequently, the conclusions about the utility of the NAIRU as a macroeconomic indicator for expansions and recessions.     

Distributed formation output regulation of switching heterogeneous multi-agent systems

In this article, the distributed formation output regulation problem of linear heterogeneous multi-agent systems with uncertainty under switching topology is considered. It is a generalised framework for multi-agent coordination problems, which contains or concerns a variety of important multi-agent problems in a quite unified way. Its background includes active leader following formation for the agents to maintain desired relative distances and orientations to the leader with a predefined trajectory, and multi-agent formation with environmental inputs. With the help of canonical internal model we design a distributed dynamic output feedback to handle the distributed formation output regulation problem.     

带后备电池的多路隔离输出开关电源

介绍了一种带后备电池的多路隔离输出开关电源,可用于大功率器件驱动电路的供电。在市电掉电的情况下,后备电池立即接入系统,保证多路输出开关电源的正常工作,提高整个驱动供电电源的可靠性。     

Cooperative output regulation of heterogeneous multiagent systems based on event‐triggered control with fixed and switching topologies

This paper addresses the cooperative output regulation problem of multiagent systems with fixed and switching topologies. Each agent is a heterogeneous linear system, and the output of the exosystem can be available to only a subset of agents. For the agents that can directly access the exosystem, a common observer based on an event‐triggered strategy is constructed to estimate the exogenous signal for feedback control design. For the rest of the agents, estimators based on an event‐triggered mechanism to acquire the estimation value of the exogenous signal are designed under some essential assumptions. A decentralized event‐triggered formulation is considered first by applying a Lyapunov function for a fixed topology. Furthermore, a topology‐dependent triggering condition and the average dwell‐time switching law are deduced simultaneously by using multiple Lyapunov functions for switching topologies. Under communication constraints, we propose observer‐based and estimator‐based feedback controllers to solve the cooperative output regulation problem using available local information among agents. Two examples are finally provided to verify the effectiveness of the proposed theoretical results.     

基于内容交换的Web QoS

阐述了内容交换的原理,以及使用内容交换来保证端到端Web QoS的方法,并通过实例说明如何通过主机来实现Web QoS。     

Asynchronous switching output feedback control of discrete-time switched linear systems

In this paper, the problem of dynamic output-feedback control synthesis is addressed for discrete-time switched linear systems under asynchronous switching. The proposed hybrid controller consists of a standard dynamic output-feedback switching control law and an impulsive reset law induced by controller state jumps. Using the average dwell time technique incorporating with multiple quadratic Lyapunov functions, the switching control synthesis conditions for asymptotic stability with guaranteed weighted ?₂-gain performance are derived as a set of linear matrix inequalities (LMIs). The proposed hybrid synthesis scheme advances existing design methods for output-feedback asynchronous switching control of switched linear systems in two important aspects: LMI formulation of the synthesis problem; and arbitrary order of the controller state. A numerical example is used to illustrate the effectiveness and advantages of the proposed design technique.     

A single-cycle output buffered router with layered switching for Networks-on-Chips

We present a single-cycle output buffered router based on layered switching for networks on chips (NoCs). Different from state-of-the-art NoC routers, the router has three important characteristics: (1) It employs layered switching, which implements wormhole on top of virtual cut-through (VCT) switching; (2) In contrast to input buffered architectures, it adopts an output buffered architecture; (3) It is single cycle, meaning that the router pipeline takes only one cycle for all flits. Experimental results show that the router achieves up to 80% of ideal network throughput under uniform random traffic pattern. Compared with wormhole switching, layered switching achieves up to 36.9% latency reduction for 12-flit packets under uniform random traffic with an injection rate of 0.5 flit/cycle/node. Under 65 nm technology synthesized results show that its critical path has only 20 logic gates, and it reduces 11% area compared to the input virtual-channel router with the same buffer capacity.     

PIPORS: a parallel input parallel output register switching system

In order to make data exchange speed fast enough for supporting the current communication systems or networks, a high speed switching system with low transmission delay and low data loss is required. Many researchers used statistical time division multiplexing techniques to design the switching system for achieving a higher throughput. In such switching systems with n input/output ports, the internal execution speed must be n times faster than the speed of the system with single input/output port. This designing philosophy is really not an appropriate way as the demand trend for higher speed system in the future.For improving the drawbacks of the switching system mentioned above, a novel, revolutionary architecture of a Parallel Input Parallel Output Register Switching System (PIPORS) is proposed in this paper. The PIPORS is based on the interconnection of the small distributed Shared Memory Modules (SMM) and the Shift Register Switch Array (SRSA). This construction will accelerate the switching speed. In addition, the number of input/output ports of the system can easily be extended for providing a higher capacity to respond to the trend of fast increasing amount of data transferred in the system. Three simple methods to extend the input/output ports and the capacity of the internal memory are presented.For evaluating the performance of the proposed system, we made some performance comparisons among our PIPORS and Central Shared Memory Switching System (CSMS) with respect to the amount of total memory required, data loss probability, transmission delay and switching performance. It shows that a better performance can be achieved in our PIPORS.     

Parameter bounds for discrete-time Hammerstein models with bounded output errors

In this note, we present a two-stage procedure for deriving parameters bounds in Hammerstein models when the output measurement errors are bounded. First, using steady-state input-output data, parameters of the nonlinear part are tightly bounded. Then, for a given input transient sequence we evaluate tight bounds on the unmeasurable inner signal which, together with noisy output measurements are used for bounding the parameters of the linear dynamic block.     

单片机模糊控制的气体流量控制仪

本文介绍了气体流量自动控制系统的特点,功能和结构。该系统采用单片机模糊控制技术,实现对气体流量的实时测控。