Optimal Strictly Stealthy Attack Design on Cyber-Physical Systems: A Data-Driven Approach.

In this article, an issue of data-driven optimal strictly stealthy attack design for the stochastic linear invariant systems is investigated, with the aim of maximizing the system performance degradation under an energy bounded constraint and bypassing the parity-space-based attack detector. Importantly, the proposed attack policy refrains from the assumption that the system knowledge is known to attackers. A novel strictly stealthy attack sequence (SSAS), coordinating the sensor and actuator signals simultaneously, is proposed with a sufficient and necessary condition for the existence of such an attack presented. Specifically, the SSAS is parameterized as a vector in the null space of a specific matrix which is constructed by a parity matrix and the system Markov parameters. For the purpose of data-driven attack realization, modified subspace identification methods are utilized to achieve an unbiased estimation of the required parameters via the closed-loop data. On this basis, the attack design is formulated as a constrained optimization problem, an explicit solution to which is given to characterize the optimal strictly stealthy attack. Finally, the vulnerability of the cyber-physical systems is analysed from the perspective of the parameter selection for the parity space-based detector. A case study on a three-tank model verifies the efficiency of the proposed approach.

Distributed disturbance observer-based nonfragile bipartite consensus of nonlinear multiagent systems with multiple time-varying delays.

The paper concentrates on the issue of distributed disturbance observer-based nonfragile bipartite consensus within nonlinear delayed multiagent systems, encompassing both leaderless and leader-following structures. The delays under consideration are nonuniform, manifesting in the state, the nonlinearity, and the communication processes. To suppress the external disturbances and the observer gain perturbations, distributed nonfragile disturbance observers pertaining to relative output and communication delays are developed to estimate the external disturbances for each agent. Employing the developed disturbance observer, distributed control protocols for nonfragile bipartite consensus are constructed incorporating states, estimated disturbances, and communication delays. These protocols can ensure bipartite consensus, compensate for external disturbances, and tolerate uncertainties in control gain. New augmented Lyapunov-Krasovskii functions are formulated by introducing the triple integral term and the augmented vector. The new bipartite consensus criteria for the studied multiagent systems are established with less conservatism by employing the techniques on second-order Bessel-Legendre integral inequality, reciprocally convex combination, and free weight matrix. Finally, numerical simulations and comparisons are performed for both leaderless and leader-following scenarios, thereby validating and enhancing the theoretical outcomes.

Sparse Actuator Attack Detection and Identification: A Data-Driven Approach.

This article aims to investigate the data-driven attack detection and identification problem for cyber-physical systems under sparse actuator attacks, by developing tools from subspace identification and compressive sensing theories. First, two sparse actuator attack models (additive and multiplicative) are formulated and the definitions of I/O sequence and data models are presented. Then, the attack detector is designed by identifying the stable kernel representation of cyber-physical systems, followed by the security analysis of data-driven attack detection. Moreover, two sparse recovery-based attack identification policies are proposed, with respect to sparse additive and multiplicative actuator attack models. These attack identification policies are realized by the convex optimization methods. Furthermore, the identifiability conditions of the presented identification algorithms are analyzed to evaluate the vulnerability of cyber-physical systems. Finally, the proposed methods are verified by the simulations on a flight vehicle system.

Performance Optimization and Fault-Tolerance of Highly Dynamic Systems Via Q-Learning With an Incrementally Attached Controller Gain System.

High-performance and reliable control of systems that are highly dynamic and open-loop unstable is challenging but of considerable practical interest. Thus, this article investigates the performance optimization and fault tolerance of highly dynamic systems. First, an incremental control structure is proposed, where a controller gain system is attached to the predesigned controller, and by reconfiguring the controller gain system, the performance can be equivalently optimized as configuring the predesigned one. The incremental attachment of the controller gain system does not modify the existing control system, and it can be easily attached via various communication channels. Second, a structure integrating fault-tolerance strategy and hardware redundancy is proposed. Under this structure, command fusion and fault-tolerance strategies are developed where the control commands from different control units are optimally fused, and each control unit can be reconfigured w.r.t. the performance of the other ones. Furthermore, Q -learning algorithms are developed to realize the proposed structures and strategies in real-time model-freely. As such, varying operational conditions of the highly dynamic system can be tackled. Finally, the proposed structures and algorithms are validated case by case to show their effectiveness.

Simultaneous Prediction of Wrist and Hand Motions via Wearable Ultrasound Sensing for Natural Control of Hand Prostheses.

Simultaneous prediction of wrist and hand motions is essential for the natural interaction with hand prostheses. In this paper, we propose a novel multi-out Gaussian process (MOGP) model and a multi-task deep learning (MTDL) algorithm to achieve simultaneous prediction of wrist rotation (pronation/supination) and finger gestures for transradial amputees via a wearable ultrasound array. We target six finger gestures with concurrent wrist rotation in four transradial amputees. Results show that MOGP outperforms previously reported subclass discriminant analysis for both predictions of discrete finger gestures and continuous wrist rotation. Moreover, we find that MTDL has the potential to improve the accuracy of finger gesture prediction compared to MOGP and classification-specific deep learning, albeit at the expense of reducing the accuracy of wrist rotation prediction. Extended comparative analysis shows the superiority of ultrasound over surface electromyography. This paper prioritizes exploring the performance of wearable ultrasound on the simultaneous prediction of wrist and hand motions for transradial amputees, demonstrating the potential of ultrasound in future prosthetic control. Our ultrasound-based adaptive prosthetic control dataset (Ultra-Pro) will be released to promote the development of the prosthetic community.

Fixed-time ESO based fixed-time integral terminal sliding mode controller design for a missile.

This paper studies a novel fixed-time extended state observer based fixed-time integral terminal sliding mode controller for partial integrated guidance and control design. Firstly, a class of arbitrary-order systems with fixed-time stability is proposed by utilizing homogeneous approach, whose upper bound of convergence time is given. Then, an arbitrary-order fixed-time integral terminal sliding mode control is designed based on the proposed arbitrary-order fixed-time stable system, which avoids the singular problem. Subsequently, this paper constructs a new fixed-time extended state observer to further actively compensate for the disturbance caused by unknown target acceleration. Finally, numerical simulations show the effectiveness of the proposed controller.

Data-Driven False Data-Injection Attack Design and Detection in Cyber-Physical Systems.

In this article, a data-driven design scheme of undetectable false data-injection attacks against cyber-physical systems is proposed first, with the aid of the subspace identification technique. Then, the impacts of undetectable false data-injection attacks are evaluated by solving a constrained optimization problem, with the constraints of undetectability and energy limitation considered. Moreover, the detection of designed data-driven false data-injection attacks is investigated via the coding theory. Finally, the simulations on the model of a flight vehicle are illustrated to verify the effectiveness of the proposed methods.

Effect of kinesio taping on hemiplegic shoulder pain: A systematic review and meta-analysis of randomized controlled trials.

OBJECTIVE: The aim of this study was to evaluate the effectiveness of kinesio taping for the management of hemiplegic shoulder pain. DATA SOURCES: MEDLINE, EMBASE, Web of Science, CENTRAL, CNKI, Wan Fang databases and the grey literature research were searched from inception to July 2020. METHODS: We considered randomized controlled trials in English or Chinese that used kinesio taping for the treatment of hemiplegic shoulder pain. Two reviewers independently screened the articles, scored the methodological quality using the PEDro scale, assessed risk of bias using the Cochrane's risk of bias tool and extracted the data. The outcomes included pain, motor function of the upper limb, magnitude of shoulder subluxation and activities of daily living post-intervention. RESULTS: A total of nine studies (n = 424) met the inclusion criteria. A meta-analysis demonstrated a significant effect of kinesio taping on pain (mean difference(MD)= -1.45, 95% confidence interval(CI): -1.98 to-0.92 cm, p < 0.0001), motor function of upper limb (MD = 4.22,95%CI: 3.49 to 4.95, p < 0.00001), magnitude of shoulder subluxation (standardized mean difference(SMD) = -0.65, 95%CI: -0.95 to -0.35, p < 0.0001) and activities of daily living (MD = 6.86, 95% CI: 3.99 to 9.73, p < 0.00001) post-intervention. CONCLUSION: This meta-analysis suggests a beneficial effect of kinesio taping for reducing shoulder subluxation, improving motor function of the upper limb and activities of daily living in patients with hemiplegic shoulder pain post-intervention, which could not be interpreted simply as a placebo effect. And it was associated with reduced pain for patients with chronic stroke.

Environmental barriers, functioning and quality of life in 2008 Wenchuan earthquake victims with spinal cord injury eight years after the disaster: A cross-sectional study.

OBJECTIVE: To examine environmental barriers, func-tioning, and quality of life in Wenchuan earthquake survivors with spinal cord injury. DESIGN: Cross-sectional study. SUBJECTS: Thirty-two adult Wenchuan earthquake survivors with spinal cord injury. METHODS: Data were collected on environmental factors with the Nottwil Environmental Factors Inventory Short Form (NEFI-SF), physical and mental functioning with the 36-item Short-Form Health Survey (SF-36), and quality of life with the World Health Organization Quality of Life-BREF (WHOQOL-BREF). Descriptive analysis of environmental barriers and comparisons of SF-36 and WHOQOL-BREF domain scores with normative data were performed. Variations in outcomes across demographic and lesion characteristics were examined using Mann-Whitney U test. Associations of NEFI-SF with SF-36 and WHOQOL-BREF domain scores were explored using Spearman's correlation. RESULTS: Wenchuan earthquake survivors with spinal cord injury were affected by a large number of environmental barriers. Their functioning and quality of life were considerably reduced in comparison with respective reference populations. Neither environmental barriers nor functioning or quality of life varied systematically by demographic and lesion characteristics. Increased numbers of perceived environmental barriers were strongly associated with decreased scores across SF-36 and WHOQOL-BREF sub-domains. CONCLUSION: Wenchuan earthquake survivors with SCI faced a considerable number of environmental barriers and showed decreased functioning and quality of life. Environmental barriers were strongly related to functioning and quality of life.

Adaptive fault-tolerant PI tracking control for ship propulsion system.

This paper studies the fault-tolerant tracking control issues for the ship propulsion system. The propulsion system with one engine and one propeller is first introduced, and the faulty model with loss of actuator effectiveness is formulated. By utilizing the H∞ output feedback technique, the nominal proportional-integral (PI) controller is designed with its gains analytically determined, yet ensuring the desired tracking performance in the fault-free case. Furthermore, to accommodate loss of actuator effectiveness faults, a fault-tolerant PI control scheme is proposed, including the adaptive tuning law to adjust controller gains online. The proposed strategy is not only simple and easy to implement, but also guarantees the graceful tracking performance and fault-tolerant capability. Finally, a case study on the ship propulsion system is presented to demonstrate the effectiveness of the proposed methods.

Physical function, pain, quality of life and life satisfaction of amputees from the 2008 Sichuan earthquake: A prospective cohort study.

OBJECTIVES: To examine the development and determinants of long-term outcomes for earthquake victims with amputations, including physical function, pain, quality of life and life satisfaction. DESIGN: Prospective cohort study with 2-3 measurement points. SUBJECTS: A total of 72 people who underwent amputations following the 2008 Sichuan Earthquake and resided in Mianzhu County, Sichuan Province, China were enrolled in the study. Of these, 27 people were lost to follow-up. METHODS: Data on pain (visual analogue scale) and physical function (Barthel Index) were collected at 3 measurement points (2009, 2010 and 2012), and data on quality of life (Medical Outcomes Short-Form 36) and life satisfaction (Life Satisfaction Questionnaire-11) were collected at 2 measurement points (2010 and 2012). Data were analysed with mixed effects regression. RESULTS: Pain severity declined significantly and physical function increased by 2012. Quality of life and life satisfaction remained relatively stable between 2010 and 2012, while quality of life was significantly lower than reference values from the general population. Illiteracy and lower extremity amputations were associated with lower quality of life and life satisfaction in several domains. CONCLUSION: While amputees' functioning and pain were improved over time, quality of life and life satisfaction did not change. Illiterate earthquake survivors and those with lower extremity amputations are at particular risk of low quality of life and life satisfaction, and may require additional attention in future earthquake rehabilitation programs.

Factors affecting functional outcome of Sichuan-earthquake survivors with tibial shaft fractures: a follow-up study.

OBJECTIVE: The aim of this study was to analyse the various factors affecting functional recovery of earthquake survivors with tibial shaft fractures in Sichuan, China, and to provide a clinical reference for the future management of people injured in earthquakes. METHODS: A total of 174 earthquake survivors with tibial shaft fractures were investigated using a face-to-face survey 15 months after the earthquake. Functional recovery after fracture was evaluated by Johner-Wruhs' criteria. Thirteen of the parameters that may influence functional recovery after fracture were included. Univariate and multiple stepwise logistic regression analyses were employed. RESULTS: Functional recovery was positively associated with rehabilitation intervention (odds ratio 5.3 (95% confidence interval 2.38-11.67)), but negatively correlated with the immobilization duration (odds ratio (per 10 days increase) 0.87 (95% confidence interval 0.798-0.947)), age (odds ratio (per 10 years increase) 0.54 (95% confidence interval 0.418-0.707)) and depressive symptomatology (odds ratio 0.21 (95% confidence interval 0.063-0.716)). CONCLUSION: Functional recovery of post-earthquake survivors with tibial shaft fractures is related mainly to availability of rehabilitation intervention, duration of immobilization, post-earthquake depressive symptomatology, and age. These results may support the future development of strategies for optimizing functional recovery of survivors with lower limb fracture after massive natural disasters.