Resilient control of networked control systems with stochastic denial of service attacks

This paper focuses on resilient control of networked control systems (NCSs) under the denial of service (DoS) attacks characterized by a Markov process. Firstly, based on the game between attack strategies and defense strategies, the packet dropouts induced by DoS attacks are modeled as a Markov process. Secondly, an NCS under DoS attacks is modeled as a Markovian jump linear system. Then, by use of the Lyapunov theory and the derived NCS model, four theorems are given for the system stability analysis and controller design. Finally, a numerical example is used to illustrative the effectiveness of proposed method

Minimal leader selection in general linear multi-agent systems with switching topologies : leveraging submodularity ratio

In multi-agent systems with leader-follower dynamics, choosing a subset of agents as leaders is a critical step in achieving the desired coordination performance. In this study, by considering consensus tracking for general linear multi-agent systems under switching topologies, we address the problem of selecting a minimum-size set of leaders by leveraging the submodularity ratio. First, using the dwell time technique, a criterion is derived to ensure that the states of all agents can converge to a reference trajectory that is directly tracked by each leader. Second, exploiting the derived consensus tracking criterion, the metrics with a structure of the Euclidean distance between specific vectors and the space spanned by an iteratively updated matrix are established to identify a set of leaders, and then the corresponding bound of the submodularity ratio is proposed. Third, combining the derived criterion and the constructed metrics, a leader selection scheme is presented together with three polynomial-time algorithms, and the related provable optimality bound of each algorithm can be obtained by leveraging the proposed bound of the submodularity ratio. Finally, illustrative examples are provided to verify the effectiveness of the proposed leader selection scheme

Shear Mode Bulk Acoustic Resonator Based on Inclined c-Axis AlN Film for Monitoring of Human Hemostatic Parameters

Measurement of hemostatic parameters is essential for patients receiving long-term oral anticoagulant agents. In this paper, we present a shear mode bulk acoustic resonator based on an inclined c-axis aluminum nitride (AlN) film for monitoring the human hemostatic parameters. During the blood coagulation process, the resonant frequency of the device decreases along with a step-ladder profile due to the viscosity change during the formation of fibers in blood, revealing the sequential coagulation stages. Two hemostatic parameters with clinical significance, prothrombin time (PT) along with its derived measure of international normalized ratio (INR), are determined from time-frequency curves of the device. Furthermore, the resonator is compared with a commercial coagulometer by monitoring the hemostatic parameters for one month in a patient taking the oral anticoagulant. The results are consistent. In addition, thanks to the excellent potential for integration, miniaturization and the availability of direct digital signals, the proposed device has promising application for point of care coagulation monitoring

Analysis of Retinal Microstructure in Eyes with Dissociated Optic Nerve Fiber Layer (DONFL) Appearance following Idiopathic Macular Hole Surgery: An Optical Coherence Tomography Study

(1) Purpose: This study aimed to evaluate morphological changes of the retina in eyes with dissociated optic nerve fiber layer (DONFL) appearance following internal limiting membrane (ILM) peeling for full-thickness idiopathic macular hole (IMH) on spectral-domain optical coherence tomography (SD-OCT). (2) Methods: We retrospectively analyzed 39 eyes of 39 patients with type 1 macular hole closure after a vitrectomy with ILM peeling procedure at a six-month minimum postoperative follow-up. The retinal thickness maps and cross-sectional OCT images were obtained from a clinical OCT device. The cross-sectional area of the retinal nerve fiber layer (RNFL) on cross-sectional OCT images was manually measured by ImageJ software. (3) Results: The inner retinal layers (IRLs) thickness thinned down much more in the temporal quadrant than in nasal quadrants at 2 and 6 months postoperatively (p < 0.001). However, the cross-sectional area of the RNFL did not change significantly at 2 and 6 months postoperatively (p > 0.05) when compared to preoperative data. In addition, the thinning of the IRL did not correlate with the best-corrected visual acuity (BCVA) at 6 months postoperatively. (4) Conclusions: The thickness of the IRL decreased in eyes with a DONFL appearance after ILM peeling for IMH. The thickness of the IRL decreased more in the temporal retina than in the nasal retina, but the change did not affect BCVA during the 6 months after surgery

Unique ventifacts and related aeolian conditions at Zhurong landing site, Utopia Planitia, Mars

International audienceOn 14 May 2021 (UTC), China’s first Mars rover, Zhurong, has opened a new frontier of in-situ Mars exploration when it landed in the vast terrain of southern Utopia Planitia [1]. The first year of Zhurong’s journey has provided close-up views of the landscape. Traversing south, the rover was able to visit several bright dunes and witness serveral ventifacts [2]. For the ventifacts, [2] described some being pitted and layered with flaky structures, while [3] has inferred that some of the low-lying ventifacts were exposed sulfate duricrusts, suggesting possible underground aqueous activity. Here, we have identified that the flaky features are aeolian and their formation relates to certain aeolian conditions

Unique ventifacts and related aeolian conditions at Zhurong landing site, Utopia Planitia, Mars

International audienceOn 14 May 2021 (UTC), China’s first Mars rover, Zhurong, has opened a new frontier of in-situ Mars exploration when it landed in the vast terrain of southern Utopia Planitia [1]. The first year of Zhurong’s journey has provided close-up views of the landscape. Traversing south, the rover was able to visit several bright dunes and witness serveral ventifacts [2]. For the ventifacts, [2] described some being pitted and layered with flaky structures, while [3] has inferred that some of the low-lying ventifacts were exposed sulfate duricrusts, suggesting possible underground aqueous activity. Here, we have identified that the flaky features are aeolian and their formation relates to certain aeolian conditions