Design of robust control for uncertain fuzzy quadruple-tank systems with time-varying delays

Producción CientíficaThe robust H∞ observer-based control design is addressed here for non-linear Takagi-Sugeno (T-S) fuzzy systems with time-varying delays, subject to uncertainties and external disturbances. This is motivated by the quadruple-tank with time delay control problem. The observer design methodology is based on constructing an appropriate Lyapunov–Krasovskii functional (LKF) for an augmented system formed from the original and the delayed states. The bilinear terms are transferred to the linear matrix inequalities, thanks to a change of variables which can be solved in one step. Furthermore, by employing the L2 performance index, the adverse effects of persistent bounded disturbances is largely avoided. The proposed method has the advantage of relating the controller and Lyapunov function to both the original and delayed states. Then, the controller and observer gains are obtained simultaneously by solving these inequalities with off-the-shelf software (Yalmip/MATLAB toolbox). Finally, an application to a simulated quadruple-tank system with time delay is carried out to demonstrate the benefits of the proposed technique, showing a compromise between controller simplicity and robustness that outperforms previous approaches.Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCL

Safety and efficacy of fluoxetine on functional outcome after acute stroke (AFFINITY): a randomised, double-blind, placebo-controlled trial

Background Trials of fluoxetine for recovery after stroke report conflicting results. The Assessment oF FluoxetINe In sTroke recoverY (AFFINITY) trial aimed to show if daily oral fluoxetine for 6 months after stroke improves functional outcome in an ethnically diverse population. Methods AFFINITY was a randomised, parallel-group, double-blind, placebo-controlled trial done in 43 hospital stroke units in Australia (n=29), New Zealand (four), and Vietnam (ten). Eligible patients were adults (aged ≥18 years) with a clinical diagnosis of acute stroke in the previous 2–15 days, brain imaging consistent with ischaemic or haemorrhagic stroke, and a persisting neurological deficit that produced a modified Rankin Scale (mRS) score of 1 or more. Patients were randomly assigned 1:1 via a web-based system using a minimisation algorithm to once daily, oral fluoxetine 20 mg capsules or matching placebo for 6 months. Patients, carers, investigators, and outcome assessors were masked to the treatment allocation. The primary outcome was functional status, measured by the mRS, at 6 months. The primary analysis was an ordinal logistic regression of the mRS at 6 months, adjusted for minimisation variables. Primary and safety analyses were done according to the patient's treatment allocation. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12611000774921. Findings Between Jan 11, 2013, and June 30, 2019, 1280 patients were recruited in Australia (n=532), New Zealand (n=42), and Vietnam (n=706), of whom 642 were randomly assigned to fluoxetine and 638 were randomly assigned to placebo. Mean duration of trial treatment was 167 days (SD 48·1). At 6 months, mRS data were available in 624 (97%) patients in the fluoxetine group and 632 (99%) in the placebo group. The distribution of mRS categories was similar in the fluoxetine and placebo groups (adjusted common odds ratio 0·94, 95% CI 0·76–1·15; p=0·53). Compared with patients in the placebo group, patients in the fluoxetine group had more falls (20 [3%] vs seven [1%]; p=0·018), bone fractures (19 [3%] vs six [1%]; p=0·014), and epileptic seizures (ten [2%] vs two [<1%]; p=0·038) at 6 months. Interpretation Oral fluoxetine 20 mg daily for 6 months after acute stroke did not improve functional outcome and increased the risk of falls, bone fractures, and epileptic seizures. These results do not support the use of fluoxetine to improve functional outcome after stroke

Stabilité et stabilisation des systèmes de retard à paramètres linéaires et variables avec actionneurs saturation

La thèse est consacrée au développement d'une méthodologie de stabilité et de stabilisation pour les systèmes linéaires paramètres-dépendants et à retard soumis à la saturation de la commande. Dans le processus industriel, l'amplitude du signal de commande est généralement limitée par les contraintes de sécurité, les limites du cycle physique, etc. Pour cette raison, un outil de synthèse et d'analyse approprié est nécessaire pour décrire avec précision les caractéristiques des systèmes saturés à paramètres linéaires variables. Dans la première partie, une forme dépendante des paramètres de la condition de secteur généralisée (GSC) est considérée pour résoudre le problème de stabilisation saturée. Plusieurs stratégies de contrôle de rétroaction sont étudiées pour stabiliser les systèmes LPV/qLPV saturés. Conditions de stabilisation nécessaires et suffisantes via la formulation d'inégalité matricielle linéaire paramétrée proposée pour les contrôleurs de retour d'état conformes aux exigences de conception (c'est-à-dire l'ensemble admissible des conditions initiales, la région estimée du domaine de convergence asymptotique, la stabilité et les performances robustes sous l'influence des perturbations, etc.). La relaxation des PLMI conçus est illustrée par les résultats de comparaison à l'aide d'une fonction de Lyapunov dépendante des paramètres. Dans la deuxième partie, les développements de stabilité dépendant du délai basés sur la fonctionnelle de Lyapunov-Krasovskii (LKF) sont présentés. Les techniques modernes de limitation avancées sont utilisées avec un équilibre entre conservatisme et complexité de calcul. Ensuite, des analyses de stabilisation de saturation pour les contrôleurs d'ordonnancement de gain. Inspirée des méthodes de système à retard incertain, une nouvelle condition de stabilisation est dérivée de l'analyse de stabilisation dépendante du retard pour le système à retard LPV soumis à des contraintes de saturation. Dans cet aspect, les contrôleurs de rétroaction à programmation de gain stabilisants améliorent les performances et la stabilité du système saturé et fournissent un grand domaine d'attraction. On peut souligner que la formulation dérivée est générale et peut être utilisée pour le contrôle de la conception de nombreux systèmes dynamiques. Enfin, pour maximiser la région d'attraction tout en garantissant la stabilité asymptotique du système en boucle fermée, un problème d'optimisation est inclus dans la stratégie de conception de commande proposéeThe dissertation is devoted to developing a methodology of stability and stabilization for the linear parameter-dependent (PD) and time-delay systems (TDSs) subject to control saturation. In the industrial process, control signal magnitude is usually bounded by the safety constraints, the physical cycle limits, and so on. For this reason, a suitable synthesis and analysis tool is needed to accurately describe the characteristics of the saturated linear parameter-varying (LPV) systems. In the part one, a parameter-dependent form of the generalized sector condition (GSC) is considered to solve the saturated stabilization problem. Several feedback control strategies are investigated to stabilize the saturated LPV/qLPV systems. Necessary and sufficient stabilization conditions via the parameterized linear matrix inequality (PLMI) formulation proposed for the feedback controllers conforming to the design requirements (i.e., the admissible set of the initial conditions, the estimated region of the asymptotic convergence domain, the robust stability and performance with the influence of perturbations, Etc.). The relaxation of the designed PLMIs is shown through the comparison results using a parameter-dependent Lyapunov function (PDLF). In the second part, the delay-dependent stability developments based on Lyapunov-Krasovskii functional (LKF) are presented. The modern advanced bounding techniques are utilized with a balance between conservatism and computational complexity. Then, saturation stabilization analyzes for the gain-scheduling controllers. Inspired by uncertain delay system methods, a novel stabilization condition is derived from the delay-dependent stabilizing analysis for the LPV time-delay system subject to saturation constraints. In this aspect, the stabilizing gain-scheduling feedback controllers improve the performance and stability of the saturated system and provide a large attraction domain. It can be emphasized that the derived formulation is general and can be used for the design control of many dynamic systems. Finally, to maximize the attraction region while guaranteeing the asymptotic stability of the closed-loop system, an optimization problem is included to the proposed control design strateg

Stabilité et stabilisation des systèmes de retard à paramètres linéaires et variables avec actionneurs saturation

The dissertation is devoted to developing a methodology of stability and stabilization for the linear parameter-dependent (PD) and time-delay systems (TDSs) subject to control saturation. In the industrial process, control signal magnitude is usually bounded by the safety constraints, the physical cycle limits, and so on. For this reason, a suitable synthesis and analysis tool is needed to accurately describe the characteristics of the saturated linear parameter-varying (LPV) systems. In the part one, a parameter-dependent form of the generalized sector condition (GSC) is considered to solve the saturated stabilization problem. Several feedback control strategies are investigated to stabilize the saturated LPV/qLPV systems. Necessary and sufficient stabilization conditions via the parameterized linear matrix inequality (PLMI) formulation proposed for the feedback controllers conforming to the design requirements (i.e., the admissible set of the initial conditions, the estimated region of the asymptotic convergence domain, the robust stability and performance with the influence of perturbations, Etc.). The relaxation of the designed PLMIs is shown through the comparison results using a parameter-dependent Lyapunov function (PDLF). In the second part, the delay-dependent stability developments based on Lyapunov-Krasovskii functional (LKF) are presented. The modern advanced bounding techniques are utilized with a balance between conservatism and computational complexity. Then, saturation stabilization analyzes for the gain-scheduling controllers. Inspired by uncertain delay system methods, a novel stabilization condition is derived from the delay-dependent stabilizing analysis for the LPV time-delay system subject to saturation constraints. In this aspect, the stabilizing gain-scheduling feedback controllers improve the performance and stability of the saturated system and provide a large attraction domain. It can be emphasized that the derived formulation is general and can be used for the design control of many dynamic systems. Finally, to maximize the attraction region while guaranteeing the asymptotic stability of the closed-loop system, an optimization problem is included to the proposed control design strategyLa thèse est consacrée au développement d'une méthodologie de stabilité et de stabilisation pour les systèmes linéaires paramètres-dépendants et à retard soumis à la saturation de la commande. Dans le processus industriel, l'amplitude du signal de commande est généralement limitée par les contraintes de sécurité, les limites du cycle physique, etc. Pour cette raison, un outil de synthèse et d'analyse approprié est nécessaire pour décrire avec précision les caractéristiques des systèmes saturés à paramètres linéaires variables. Dans la première partie, une forme dépendante des paramètres de la condition de secteur généralisée (GSC) est considérée pour résoudre le problème de stabilisation saturée. Plusieurs stratégies de contrôle de rétroaction sont étudiées pour stabiliser les systèmes LPV/qLPV saturés. Conditions de stabilisation nécessaires et suffisantes via la formulation d'inégalité matricielle linéaire paramétrée proposée pour les contrôleurs de retour d'état conformes aux exigences de conception (c'est-à-dire l'ensemble admissible des conditions initiales, la région estimée du domaine de convergence asymptotique, la stabilité et les performances robustes sous l'influence des perturbations, etc.). La relaxation des PLMI conçus est illustrée par les résultats de comparaison à l'aide d'une fonction de Lyapunov dépendante des paramètres. Dans la deuxième partie, les développements de stabilité dépendant du délai basés sur la fonctionnelle de Lyapunov-Krasovskii (LKF) sont présentés. Les techniques modernes de limitation avancées sont utilisées avec un équilibre entre conservatisme et complexité de calcul. Ensuite, des analyses de stabilisation de saturation pour les contrôleurs d'ordonnancement de gain. Inspirée des méthodes de système à retard incertain, une nouvelle condition de stabilisation est dérivée de l'analyse de stabilisation dépendante du retard pour le système à retard LPV soumis à des contraintes de saturation. Dans cet aspect, les contrôleurs de rétroaction à programmation de gain stabilisants améliorent les performances et la stabilité du système saturé et fournissent un grand domaine d'attraction. On peut souligner que la formulation dérivée est générale et peut être utilisée pour le contrôle de la conception de nombreux systèmes dynamiques. Enfin, pour maximiser la région d'attraction tout en garantissant la stabilité asymptotique du système en boucle fermée, un problème d'optimisation est inclus dans la stratégie de conception de commande proposé

Robust observer–based control for TS Fuzzy models Application to vehicle lateral dynamics

International audienceThis paper deals with the observer based robustcontrol design problem for TS fuzzy systems with time-varyinguncertain parameters. Sufficient design conditions of the fuzzyobserver and the fuzzy controller are first proposed. Due to theuse of Young relation, and the cone-complementary, the nonconvexand Bilinear problems are then converted into convexoptimization one with LMI constraints. Controller and observergains are obtained under ℒ2-bounded disturbance and ℒ2-norminput constraint by set feasible solutions of LMI conditions. Theeffectiveness of the proposed fuzzy controller and fuzzyobserver design methodology is finally demonstrated throughnumerical simulations on vehicle lateral dynamic model

Robust TS-Fuzzy state and output feedback controller synthesis for saturated vehicle System

International audienceThis paper addresses robust control design problem for parameter dependent (PD) systems subject to actuator saturation. The dead-zone nonlinearity is considered for regional stability and performance analysis of control design strategy. The parallel distributed compensation static output feedback controller is derived in new gain-scheduling scheme satisfied the generalized sector condition. Based on the fuzzy Lyapunov function approach, the parameterized stabilization non-convex conditions are reformulated in linear matrix inequalities (LMI) by congruence transformations. The proposed method leads to less conservative constraint on saturated PD controller synthesis. The effectiveness of the design methodology is demonstrated through simulations

Resveratrol suppressed lps-induced cox-2 VIA miR-146a-5p inhibition in raw246.7 cells

Trans-resveratrol (Res) is a well-known natural stilbene frequently found in grapes which have been reported to possess antioxidant, anti-cancer activities and inhibited COX-2 expression. MicroRNAs (miRNAs) are short endogenous non-coding RNAs involved in the regulation of mRNA stability and protein synthesis. In our research, resveratrol isolated from Vitis heyneana Roem. & Schult Vitis heyneana was observed to suppress lipopolysaccharides (LPS)-induced COX-2 expression in Raw264.7 cells in a dose dependent manner. Using qPCR it was revealed that LPS induced the expression of miR-25, miR- 125a, miR-125b, miR-146a-5p, miR-146a-3p and miR-455. However, we only observed miR-146a-5p expression significantly decreased in resveratrol compared to untreated-control group. In addition, resveratrol abrogated the effect of miR-146a-5p mimic induced-COX-2 expression in Raw264.7 cells. Taken together, this study demonstrated for the first time the involvement of miR-146a-5p in resveratrol inhibited LPS-induced COX-2 expression in Raw264.7 cells

Economic burden of venous thromboembolism in surgical patients: A propensity score analysis from the national claims database in Vietnam.

BACKGROUND:Venous thromboembolism (VTE) associated with surgery can cause serious comorbidities or death and imposes a substantial economic burden to society. The study examined VTE cases after surgery to determined how this condition imposed an economic burden on patients based on the national health insurance reimbursement database. Methods: This retrospective analysis adopted the public payer's perspective. The direct medical cost was estimated using data from the national claims database of Vietnam from Jan 1, 2017 to Sep 31, 2018. Adult patients who underwent surgeries were recruited for the study. Patients with a diagnostic code of up to 90 days after surgery were considered VTE cases with the outcome measure being the surgery-related costs within 90 days. RESULTS:The 90-day cost of VTE patients was found to be US$2,939. The rate of readmission increased by 5.4 times, the rate of outpatient visits increased by 1.8 times and total costs over 90 days in patients with VTE undergoing surgery increased by 2.2 times. Estimation using propensity score matching method showed that an increase of US$1,019 in the 90-day cost of VTE patients. CONCLUSION:The VTE-related costs can be used to assess the potential economic benefit and cost-savings from prevention efforts

Zoonotic diseases from birds to humans in Vietnam: possible diseases and their associated risk factors

In recent decades, exceeding 60% of infectious cases in human beings are originated from pathogenic agents related to feral or companion animals. This figure continues to swiftly increase due to excessive exposure between human and contaminated hosts by means of applying unhygienic farming practices throughout society. In Asia countries—renowned for lax regulation towards animal-trading markets—have experienced tremendous outbreaks of zoonotic diseases every year. Meanwhile, various epidemic surges were first reported in the residential area of China—one of the largest distributor of all animal products on the planet. Some noticeable illnesses comprising of A/H5N1 or H7N9—known as avian influenza which transmitted from poultry and also wild birds—have caused inevitable disquiet among inhabitants. Indeed, poultry farming industry in China has witnessed dynamic evolution for the past two decades, both in quantity and degree of output per individual. Together with this pervasive expansion, zoonotic diseases from poultry have incessantly emerged as a latent threat to the surrounding residents in entire Asia and also European countries. Without strict exporting legislation, Vietnam is now facing the serious problem in terms of poultry distribution between the two countries’ border. Even though several disease investigations have been conducted by many researchers, the disease epidemiology or transmission methods among people remained blurred and need to be further elucidated. In this paper, our aim is to provide a laconic review of common zoonotic diseases spread in Vietnam, outstanding cases and several factors predisposing to this alarming situation

Twelve-Month Outcomes of the AFFINITY Trial of Fluoxetine for Functional Recovery After Acute Stroke: AFFINITY Trial Steering Committee on Behalf of the AFFINITY Trial Collaboration

Background and Purpose: The AFFINITY trial (Assessment of Fluoxetine in Stroke Recovery) reported that oral fluoxetine 20 mg daily for 6 months after acute stroke did not improve functional outcome and increased the risk of falls, bone fractures, and seizures. After trial medication was ceased at 6 months, survivors were followed to 12 months post-randomization. This preplanned secondary analysis aimed to determine any sustained or delayed effects of fluoxetine at 12 months post-randomization. Methods: AFFINITY was a randomized, parallel-group, double-blind, placebo-controlled trial in adults (n=1280) with a clinical diagnosis of stroke in the previous 2 to 15 days and persisting neurological deficit who were recruited at 43 hospital stroke units in Australia (n=29), New Zealand (4), and Vietnam (10) between 2013 and 2019. Participants were randomized to oral fluoxetine 20 mg once daily (n=642) or matching placebo (n=638) for 6 months and followed until 12 months after randomization. The primary outcome was function, measured by the modified Rankin Scale, at 6 months. Secondary outcomes for these analyses included measures of the modified Rankin Scale, mood, cognition, overall health status, fatigue, health-related quality of life, and safety at 12 months. Results: Adherence to trial medication was for a mean 167 (SD 48) days and similar between randomized groups. At 12 months, the distribution of modified Rankin Scale categories was similar in the fluoxetine and placebo groups (adjusted common odds ratio, 0.93 [95% CI, 0.76–1.14]; P =0.46). Compared with placebo, patients allocated fluoxetine had fewer recurrent ischemic strokes (14 [2.18%] versus 29 [4.55%]; P =0.02), and no longer had significantly more falls (27 [4.21%] versus 15 [2.35%]; P =0.08), bone fractures (23 [3.58%] versus 11 [1.72%]; P =0.05), or seizures (11 [1.71%] versus 8 [1.25%]; P =0.64) at 12 months. Conclusions: Fluoxetine 20 mg daily for 6 months after acute stroke had no delayed or sustained effect on functional outcome, falls, bone fractures, or seizures at 12 months poststroke. The lower rate of recurrent ischemic stroke in the fluoxetine group is most likely a chance finding. REGISTRATION: URL: http://www.anzctr.org.au/ ; Unique identifier: ACTRN12611000774921