Switching-like event-triggered control of uncertain NCSs under delay distribution and DoS attacks.

The paper addresses the switching-like event-triggered control for uncertain networked control systems with time-varying delay under DoS attacks. First of all, to reduce the communication burden, a switching-like event-triggered mechanism is designed to automatically select the trigger condition according to whether the system is under DoS attacks, which have the advantage of reducing the number of data packets transmitted. Secondly, unlike the traditional assumption of time-varying delay, here it satisfies the condition that the probability is known, and combines the networked control systems to propose a novel time-delay system model, which can obtain a larger upper bound on the delay. Then, by using both the Lyapunov functional method and linear matrix inequality technique, we obtain sufficient conditions of uncertain networked control systems to achieve exponentially stable in the mean square sense. Furthermore, under the common limitations of the maximum continuous packet losses caused by the DoS attacks and delay, the stability criterion is derived, which can be used to estimate the communication parameters and security controller gain. Finally, through two simulation examples, the larger upper bound of time delay, less trigger times, faster convergence rate are obtained, which verify the validity of our theoretical analysis.

Genomic analysis reveals phylogeny of Zygophyllales and mechanism for water retention of a succulent xerophyte.

Revealing the genetic basis for stress-resistant traits in extremophile plants will yield important information for crop improvement. Zygophyllum xanthoxylum, an extant species of the ancient Mediterranean, is a succulent xerophyte that can maintain a favorable water status under desert habitats; however, the genetic basis of this adaptive trait is poorly understood. Furthermore, the phylogenetic position of Zygophyllales, to which Z. xanthoxylum belongs, remains controversial. In this study, we sequenced and assembled the chromosome-level genome of Z. xanthoxylum. Phylogenetic analysis showed that Zygophyllales and Myrtales form a separated taxon as a sister to the clade comprising fabids and malvids, clarifying the phylogenetic position of Zygophyllales at whole-genome scale. Analysis of genomic and transcriptomic data revealed multiple critical mechanisms underlying the efficient osmotic adjustment using Na+ and K+ as "cheap" osmolytes that Z. xanthoxylum has evolved through the expansion and synchronized expression of genes encoding key transporters/channels and their regulators involved in Na+/K+ uptake, transport, and compartmentation. It is worth noting that ZxCNGC1;1 (cyclic nucleotide-gated channels) and ZxCNGC1;2 constituted a previously undiscovered energy-saving pathway for Na+ uptake. Meanwhile, the core genes involved in biosynthesis of cuticular wax also featured an expansion and upregulated expression, contributing to the water retention capacity of Z. xanthoxylum under desert environments. Overall, these findings boost the understanding of evolutionary relationships of eudicots, illustrate the unique water retention mechanism in the succulent xerophyte that is distinct from glycophyte, and thus provide valuable genetic resources for the improvement of stress tolerance in crops and insights into the remediation of sodic lands.

Long-term outcomes of laser dacryoplasty combined with intubation using a new silicon tube in patients with lacrimal duct obstruction.

AIM: To determine the 15-year outcomes of laser dacryoplasty (LDP) in patients with lacrimal duct obstruction; and to evaluate LDP combined with intubation using a new silicone tube to treat complicated cases. METHODS: Patients with lacrimal duct obstruction and treated with LDP between April 2000 and April 2005 were investigated retrospectively. Totally 116 eyes with completed 15-year follow-up records were included in this study. For complicated cases (52 eyes of 52 patients), both LDP and intubation using a self-made silicon tube were performed. For patients with uncomplicated obstruction (64 eyes of 61 patients), only LDP was performed. Outcomes were assessed based on results of lacrimal irrigation and degree of symptoms during follow-up. RESULTS: At the follow-up time of 15y, 81 eyes achieved full success (69.8%); 21 eyes got improved (18.1%); and 14 eyes were considered failure (12.1%). The success rate was 71.2% (37/52 eyes) for complicated cases; and 68.8% (44/64 eyes) for uncomplicated cases. No statistically significant difference between two groups was observed (P=0.961). No postoperative complication was observed. CONCLUSION: LDP is a well-tolerated, simple, and effective procedure with satisfactory long-term outcomes in selected patients, which make it a good alternative to conventional dacryocystorhinostomy. In addition, intubation with the self-made mono-canalicular silicone tube facilitates the management of complicated cases with few complications.

Observer-Based Event-Triggered Predictive Control for Networked Control Systems under DoS Attacks.

This paper studies the problem of DoS attack defense based on static observer-based event-triggered predictive control in networked control systems (NCSs). First, under the conditions of limited network bandwidth resources and the incomplete observability of the state of the system, we introduce the event-triggered function to provide a discrete event-triggered transmission scheme for the observer. Then, we analyze denial-of-service (DoS) attacks that occur on the network transmission channel. Using the above-mentioned event-triggered scheme, a novel class of predictive control algorithms is designed on the control node to proactively save network bandwidth and compensate for DoS attacks, which ensures the stability of NCSs. Meanwhile, a closed-loop system with an observer-based event-triggered predictive control scheme for analysis is created. Through linear matrix inequality (LMI) and the Lyapunov function method, the design of the controller, observer and event-triggered matrices is established, and the stability of the scheme is analyzed. The results show that the proposed solution can effectively compensate DoS attacks and save network bandwidth resources by combining event-triggered mechanisms. Finally, a smart grid simulation example is employed to verify the feasibility and effectiveness of the scheme's defense against DoS attacks.

Resilient Event-Triggered Controller Synthesis of Networked Control Systems Under Periodic DoS Jamming Attacks.

In this paper, the event-based controller synthesis problem for networked control systems under the resilient event-triggering communication scheme (RETCS) and periodic denial-of-service (DoS) jamming attacks is studied. First, a new periodic RETCS is designed under the assumption that the DoS attacks imposed by power-constrained pulsewidth-modulated jammers are partially identified, that is, the period of the jammer and a uniform lower bound on the jammer's sleeping periods are known. Second, a new state error-dependent switched system model is constructed, including the impacts of the RETCS and DoS attacks. According to this new model, the exponential stability criteria are derived by using the piecewise Lyapunov functional. In these criteria, the relationship among DoS parameters, the triggering parameters, the sampling period, and the decay rate is quantitatively characterized. Then, a criterion is also proposed to obtain the explicit expressions of the triggering parameter and event-based state feedback controller gain simultaneously. Finally, the obtained theoretical results are verified by a satellite yaw-angles control system.

Old Age Support in Urban China: The Role of Pension Schemes, Self-Support Ability and Intergenerational Assistance.

With the aim of probing into the life satisfaction of retired urban elderly in China with respect to old age support systems, this study examines the effect of pension reform with its existing inequalities across demographic and social groups on the life satisfaction of retired urban residents. The complementary role of intergenerational assistance and self-support on the life satisfaction of beneficiaries and non-beneficiaries of the pension scheme was analyzed using an ordered logit regression model with 2015 national representative data from China's Health and Retirement Longitudinal Survey. Our sample consists of a cross-sectional data set of 3815 retired urban elderly aged 60 and above. The empirical results depict that though enjoying benefits from the public pension scheme generally enhances life satisfaction, beneficiaries of the Government and Institution Pension and Enterprise Employee Basic Pension are more advantaged than beneficiaries under the Urban-Rural Social Pension Scheme. The pension inequalities existing at provincial levels and across social groups such as gender and residence registration status also affect life satisfaction adversely. Women and rural 'Hukou' registered retired urban residents are at an apparent disadvantage. Getting financial and emotional support from children broadly improves life satisfaction. Non-beneficiaries of the public pension benefit more from the financial support of children than public pension beneficiaries. There is also a positive effect of cohabiting with children on life satisfaction when retired urban residents are single as compared to being married. Financial and physical self-support ability in forms of good health, home ownership and wealth management enhance life satisfaction significantly. However, largely, retired urban elderly have a higher life satisfaction when they are financially independent of children and are supported by state pension schemes. Our findings indicate that self-support ability of the elderly together with pension benefits are more effective in enhancing the life satisfaction of retired urban elderly in China. It is recommended that government institute policies to promote personal finance initiatives by the elderly while improving the pension scheme and reducing pension inequality.

Stabilization of Neural-Network-Based Control Systems via Event-Triggered Control With Nonperiodic Sampled Data.

This paper focuses on a problem of event-triggered stabilization for a class of nonuniformly sampled neural-network-based control systems (NNBCSs). First, a new event-triggered data transmission mechanism is designed based on the nonperiodic sampled data. Different from the previous works, the proposed triggering scheme enables the NNBCSs design to enjoy the advantages of both nonuniform and event-triggered sampling schemes. Second, under the nonperiodic event-triggered data transmission scheme, the nonperiodic sampled-data three-layer fully connected feedforward neural-network (TLFCFFNN)-based event-triggered controller is constructed, and the resulting closed-loop TLFCFFNN-based event-triggered control system is modeled as a state delay system based on time-delay system modeling approach. Then, the stability criteria for the closed-loop system is formulated using Lyapunov-Krasovskii functional approach. Third, the sufficient conditions for the codesign of the TLFCFFNN-based controller and triggering parameters are given in terms of solvability of matrix inequalities to guarantee the asymptotical stability of the closed-loop system and an upper bound on the given cost function while reducing the updates of the controller. Finally, three numerical examples are provided to illustrate the effectiveness and benefits of the proposed results.