Robust sliding mode control for discrete stochastic systems with mixed time delays, randomly occurring uncertainties, and randomly occurring nonlinearities

This is the post-print version of the paper. The official published version can be accessed from the link below - Copyright @ 2012 IEEEThis paper investigates the robust sliding mode control (SMC) problem for a class of uncertain nonlinear stochastic systems with mixed time delays. Both the sectorlike nonlinearities and the norm-bounded uncertainties enter into the system in random ways, and such randomly occurring uncertainties and randomly occurring nonlinearities obey certain mutually uncorrelated Bernoulli distributed white noise sequences. The mixed time delays consist of both the discrete and the distributed delays. The time-varying delays are allowed in state. By employing the idea of delay fractioning and constructing a new Lyapunov–Krasovskii functional, sufficient conditions are established to ensure the stability of the system dynamics in the specified sliding surface by solving a certain semidefinite programming problem. A full-state feedback SMC law is designed to guarantee the reaching condition. A simulation example is given to demonstrate the effectiveness of the proposed SMC scheme.This work was supported in part by the National Natural Science Foundation of China under Grants 61028008, 60825303 and 60834003, National 973 Project under Grant 2009CB320600, the Fok Ying Tung Education Fund under Grant 111064, the Special Fund for the Author of National Excellent Doctoral Dissertation of China under Grant 2007B4, the Key Laboratory of Integrated Automation for the Process Industry Northeastern University) from the Ministry of Education of China, the Engineering and Physical Sciences Research Council (EPSRC) of the U.K. under Grant GR/S27658/01, the Royal Society of the U.K., and the Alexander von Humboldt Foundation of Germany

H ∞ sliding mode observer design for a class of nonlinear discrete time-delay systems: A delay-fractioning approach

Copyright @ 2012 John Wiley & SonsIn this paper, the H ∞  sliding mode observer (SMO) design problem is investigated for a class of nonlinear discrete time-delay systems. The nonlinear descriptions quantify the maximum possible derivations from a linear model, and the system states are allowed to be immeasurable. Attention is focused on the design of a discrete-time SMO such that the asymptotic stability as well as the H ∞  performance requirement of the error dynamics can be guaranteed in the presence of nonlinearities, time delay and external disturbances. Firstly, a discrete-time discontinuous switched term is proposed to make sure that the reaching condition holds. Then, by constructing a new Lyapunov–Krasovskii functional based on the idea of ‘delay fractioning’ and by introducing some appropriate free-weighting matrices, a sufficient condition is established to guarantee the desired performance of the error dynamics in the specified sliding mode surface by solving a minimization problem. Finally, an illustrative example is given to show the effectiveness of the designed SMO design scheme

FTMS: an efficient multicast scheduling algorithm for feedback-based two-stage switch

Session - NGNI02: Router Architecture & Switch DesignTwo major challenges in designing high-speed multicast switches are the expensive multicast switch fabric and the highly complicated central scheduler. While the recent load-balanced switch architecture uses simple unicast switch fabric and does not require a central scheduler, it is only good at handling unicast traffic. In this paper, we extend an existing load-balanced switch called feedback-based two-stage switch to support multicast traffic. In particular, an efficient multicast scheduling algorithm (FTMS) is designed. With FTMS, head-of-line (HOL) packet blocking at each input port is eliminated by adopting 'pointer' queues. To cut down queuing delay, packet replication is carried out at middle-stage ports. As compared with other multicast scheduling algorithms, simulation results show that our FTMS always provides the highest throughput. © 2012 IEEE.published_or_final_versio

On the scalability of feedback-based two-stage switch

The feedback-based two-stage switch does not require a central scheduler and can provide close to 100% throughput [3]. But the number of crosspoints required for the two stages of switch fabric is 2N2, and the average packet delay performance (even under light traffic load) is on the order of O(N) slots, where N is the switch size. To improve the performance of feedback-based two-stage switch when N is large, we adopt the Clos network for constructing a large switch from a set of smaller feedback-based switch modules. We call it a Clos-feedback switch. The potential problem of packet mis-sequencing is solved by using application-flow based load balancing. With recursive decomposition, a Clos network can degenerate into a Benes network. We show that for a Clos-feedback switch, the number of crosspoints required is reduced to 4N(2 log2N-1) and the average packet delay is cut down to O(log 2 N) slots. © 2012 IEEE.published_or_final_versio

Routing and re-routing in a LEO/MEO two-tier mobile satellite communications system with inter-satellite links

A novel LEO/MEO two-tier satellite communication system with inter-satellite links (ISLs) is proposed for providing multimedia services to global mobile users. This two-tier system architecture can reduce the transmission delay for long-distance users via MEO satellites while keeping the benefits of using LEO satellites as the service access nodes. The routing and re-routing during a handoff operation is simplified. Since the physical topology of the underlying network is time-dependent, routing is crucial for guaranteeing the delay and delay variation performance for interactive applications. We decompose the routing problem into two parts, routing in the access network and routing in the core MEO ISL network. For the access network, a new routing algorithm called the maximum holding access protocol (MHAP) is proposed for minimizing the number of LEO handoffs. For core MEO ISL network, both minimum transmission delay routing (MTDR) and minimum transmission time jitter routing (MTTJR) are investigated. Using computer simulations, we show that the proposed routing algorithms can reduce the probability of call re-routing and thus are very suitable for providing interactive multimedia services.published_or_final_versio

A novel push-and-pull hybrid data broadcast scheme for wireless information networks

A new push-and-pull hybrid data broadcast scheme is proposed for providing wireless information services to three types of clients, general, pull and priority clients. Only pull and priority clients have the back channel for sending requests to the broadcast server. There is no scalability problem with the hybrid scheme because the amount of pull and priority clients is very small. Based on the requests collected from pull and priority clients, the server estimates the interest pattern changes of the whole client population. Then the broadcast schedule on the push channel for the next broadcast cycle is adjusted. Besides the push channel, a small amount of broadcast bandwidth is allocated to a pull channel. The data to be broadcast on the pull channel is decided by the server in real-time and priority is given to requests from priority clients. Simulations show that with a time-varying client interest pattern, the average data access time for all three types of clients can be minimized. Because of the priority in using the pull channel, priority clients can achieve the lowest access time and pull clients can achieve a lower access time than general clients. To further improve the performance, the hybrid scheme with local client cache is also investigated.published_or_final_versio

Increasing Iron and Zinc in Pre-Menopausal Women and Its Effects on Mood and Cognition: A Systematic Review.

Iron and zinc are essential minerals often present in similar food sources. In addition to the adverse effects of frank iron and zinc-deficient states, iron insufficiency has been associated with impairments in mood and cognition. This paper reviews current literature on iron or zinc supplementation and its impact on mood or cognition in pre-menopausal women. Searches included MEDLINE complete, Excerpta Medica Database (EMBASE), psychINFO, psychARTICLES, pubMED, ProQuest Health and Medical Complete Academic Search complete, Scopus and ScienceDirect. Ten randomized controlled trials and one non-randomized controlled trial were found to meet the inclusion criteria. Seven studies found improvements in aspects of mood and cognition after iron supplementation. Iron supplementation appeared to improve memory and intellectual ability in participants aged between 12 and 55 years in seven studies, regardless of whether the participant was initially iron insufficient or iron-deficient with anaemia. The review also found three controlled studies providing evidence to suggest a role for zinc supplementation as a treatment for depressive symptoms, as both an adjunct to traditional antidepressant therapy for individuals with a diagnosis of major depressive disorder and as a therapy in its own right in pre-menopausal women with zinc deficiency. Overall, the current literature indicates a positive effect of improving zinc status on enhanced cognitive and emotional functioning. However, further study involving well-designed randomized controlled trials is needed to identify the impact of improving iron and zinc status on mood and cognition

Avoiding catastrophic failure in correlated networks of networks

Networks in nature do not act in isolation but instead exchange information, and depend on each other to function properly. An incipient theory of Networks of Networks have shown that connected random networks may very easily result in abrupt failures. This theoretical finding bares an intrinsic paradox: If natural systems organize in interconnected networks, how can they be so stable? Here we provide a solution to this conundrum, showing that the stability of a system of networks relies on the relation between the internal structure of a network and its pattern of connections to other networks. Specifically, we demonstrate that if network inter-connections are provided by hubs of the network and if there is a moderate degree of convergence of inter-network connection the systems of network are stable and robust to failure. We test this theoretical prediction in two independent experiments of functional brain networks (in task- and resting states) which show that brain networks are connected with a topology that maximizes stability according to the theory.Comment: 40 pages, 7 figure

The Deep Poincare Map: A Novel Approach for Left Ventricle Segmentation

Precise segmentation of the left ventricle (LV) within cardiac MRI images is a prerequisite for the quantitative measurement of heart function. However, this task is challenging due to the limited availability of labeled data and motion artifacts from cardiac imaging. In this work, we present an iterative segmentation algorithm for LV delineation. By coupling deep learning with a novel dynamic-based labeling scheme, we present a new methodology where a policy model is learned to guide an agent to travel over the image, tracing out a boundary of the ROI – using the magnitude difference of the Poincaré map as a stopping criterion. Our method is evaluated on two datasets, namely the Sunnybrook Cardiac Dataset (SCD) and data from the STACOM 2011 LV segmentation challenge. Our method outperforms the previous research over many metrics. In order to demonstrate the transferability of our method we present encouraging results over the STACOM 2011 data, when using a model trained on the SCD dataset

Integrated Dual-DFB Laser Chip-based PAM-4 Photonic-Wireless Transmission in W-band

We experimentally demonstrate lens-free photonic-wireless transmission in the W-band using a monolithically integrated dual-DFB laser, which is injection-locked by a frequency comb to generate two 90-GHz-spacing phase-stabilized carriers and modulated with a 40-Gbit/s PAM-4 signal