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In this article, the adaptive fuzzy tracking control problem for a class of uncertain strict-feedback systems with unknown nonlinearities is investigated with particular emphasis on global stability. The proposed control scheme is designed by integrating the barrier Lyapunov functions (BLFs) with the techniques of fuzzy approximation and backstepping. The novel integral BLFs (iBLFs) are introduced to overcome the design difficulties induced by the virtual control coefficients and determine a priori the compact set for guaranteeing the validity of fuzzy approximation. Compared with existing approximation-based control results, the developed controller not only guarantees global stability without requiring prior information of system nonlinearities and assumptions on the time derivatives of virtual control coefficients, but also prevents the ``explosion of complexity'' issue without attaching additional filters. The simulation results further confirm the effectiveness of the theoretical findings.

In this article, the problem of adaptive tracking control is tackled for a class of high-order nonlinear systems. In contrast to existing results, the considered system contains not only unknown nonlinear functions but also unknown rational powers. By utilizing the fuzzy approximation approach together with the barrier Lyapunov functions (BLFs), we present a new adaptive tracking control strategy. Remarkably, the BLFs are employed to determine a priori the compact set for maintaining the validity of fuzzy approximation. The primary advantage of this article is that the developed controller is independent of the powers and can be capable of ensuring global stability. Finally, two illustrative examples are given to verify the effectiveness of the theoretical findings.

This article considers the funnel output tracking control for a class of high-order uncertain nonlinear systems with the powers of positive odd rational numbers, aiming to accomplish output tracking with prescribed accuracy when both the system nonlinearities and the powers of the system are unknown. For such a purpose, a robust funnel control algorithm, i.e., a continuous, static, and universal, state-feedback controller is explicitly constructed, which achieves the state errors evolving within the predesigned performance space. Benefits of the proposed funnel output tracking controller comparing with the current approaches lie in the fact that the exact knowledge of system nonlinearities, including generally required bounding functions, is not needed to be a priori . Moreover, all the powers in each high-order subsystem are permitted to be any unknown positive odd rational numbers as well. The efficacy of the developed algorithm is confirmed through two illustrative examples.

This article considers the problem of output feedback funnel control for a class of uncertain nonlinear systems with arbitrary known relative degree. By utilizing the funnel control approach with a barrier Lyapunov function, a novel adaptive output feedback controller is constructed recursively, which accomplishes the output tracking with prescribed transient behavior. The developed control scheme features that the precise knowledge of system nonlinearities, including generally required bounding functions, is not needed. A physical example is performed to verify the effectiveness of the proposed theoretical findings.

Background Sulfation of tyrosine, yielding O-sulfotyrosine, is a common but fixed post-translational modification in eukaryotes. Patients with increased circulating O-sulfotyrosine levels experience a faster decline in renal function with progression to end-stage renal disease (ESRD). In the present study, we measured serum O-sulfotyrosine levels in individuals with chronic kidney disease (CKD) and acute kidney injury (AKI) to explore its ability to differentiate AKI from CKD. Methods A total of 135 patients (20 with AKI and 115 with CKD) were recruited prospectively for liquid chromatography-mass spectrometry assessment of circulating O-sulfotyrosine. We also studied C57BL/6 mice with CKD after 5/6 nephrectomy (Nx). Blood samples were drawn from the tail vein on Day 1, 3, 5, 7, 14, 30, 60, and 90 after CKD. Serum separation and characterization of creatinine, blood urea nitrogen (BUN), and O-sulfotyrosine was performed. Thus, the time-concentration curves of the O-sulfotyrosine level demonstrate the variation of kidney dysfunction. Results The serum levels of O-sulfotyrosine were markedly increased in patients with CKD compared with AKI. Median O-sulfotyrosine levels in CKD patients versus AKI, respectively, were as follows:243.61 ng/mL(interquartile range [IQR] = 171.90–553.86) versus 126.55 ng/mL (IQR = 48.19–185.03, P = 0.004). In patients with CKD, O-sulfotyrosine levels were positively correlated with creatinine, BUN, and Cystatin C (r = 0.63, P P P P P = 0.002; β = 0.73, P P = 0.472; r = 0.11, P = 0.655; r = 0.09, P = 0.716, respectively). The receiver operating characteristic (ROC) analysis illustrated that the area under the curve was 0.80 (95% confidence interval [CI] 0.71–0.89; P P P Conclusion Serum O-sulfotyrosine levels were observed correlated with degrading renal function and in CKD patients substantially higher than those in AKI patients. Thus serum O-sulfotyrosine facilitated the differential diagnosis of AKI from CKD.

Most existing approximation-based adaptive control (AAC) approaches for unknown pure-feedback nonaffine systems retain a dilemma that all closed-loop signals are semiglobally uniformly bounded (SGUB) rather than globally uniformly bounded (GUB). To achieve the GUB stability result, this article presents a neuro-adaptive backstepping control approach by blending the mean value theorem (MVT), the barrier Lyapunov functions (BLFs), and the technique of neural approximation. Specifically, we first resort the MVT to acquire the intermediate and actual control inputs from the nonaffine structures directly. Then, neural networks (NNs) are adopted to approximate the unknown nonlinear functions, in which the compact sets for maintaining the approximation capabilities of NNs are predetermined actively through the BLFs. It is shown that, with the developed neuro-adaptive control scheme, global stability of the resulting closed-loop system is ensured. Simulations are conducted to verify and clarify the developed approach.

It has been increasingly recognized that CWIN (cell wall invertase) and sugar transporters including STP (sugar transport protein) and SWEET (sugar will eventually be exported transporters) play important roles in plant–pathogen interactions. However, the information available in the literature comes from diverse systems and often yields contradictory findings and conclusions. To solve this puzzle, we provide here a comprehensive assessment of the topic. Our analyses revealed that the regulation of plant–microbe interactions by CWIN, SWEET, and STP is conditioned by the specific pathosystems involved. The roles of CWINs in plant resistance are largely determined by the lifestyle of pathogens (biotrophs versus necrotrophs or hemibiotrophs), possibly through CWIN-mediated salicylic acid or jasmonic acid signaling and programmed cell death pathways. The up-regulation of SWEETs and STPs may enhance or reduce plant resistance, depending on the cellular sites from which pathogens acquire sugars from the host cells. Finally, plants employ unique mechanisms to defend against viral infection, in part through a sugar-based regulation of plasmodesmatal development or aperture. Our appraisal further calls for attention to be paid to the involvement of microbial sugar metabolism and transport in plant–pathogen interactions, which is an integrated but overlooked component of such interactions.

We studied the properties of the main phases of 24 super geomagnetic storms (SGSs) (ΔSYM-H ≤ −250 nT) since 1981. We divided the SGSs into two subgroups: SGSs-I (−400 nT t∣ for six SGSs with source locations distributed in the longitudinal area ranging from E15 to W20 was larger than 1.0 nT · minute−1, while ∣ΔSYM−H/Δt∣ for the rest 18 SGSs was lower than 1.0 nT · minute−1.∣ΔSYM−H/Δt∣ for SGSs-I varied from 0.18 to 3.0 nT · minute−1. ∣ΔSYM−H/Δt∣ for eight SGSs-II varied from 0.37 to 2.2 nT · minute−1 with seven SGSs-II falling in the scope from 0.37 to 0.992 nT · minute−1.

Background We investigated whether glycemic control affects the relation between endothelial dysfunction and coronary artery disease in patients with type 2 diabetes mellitus (T2DM). Methods In 102 type 2 diabetic patients with stable angina, endothelial function was evaluated using brachial artery flow-mediated dilation (FMD) with high-resolution ultrasound, and significant stenosis of major epicardial coronary arteries (≥ 50% diameter narrowing) and degree of coronary atherosclerosis (Gensini score and SYNTAX score) were determined. The status of glycemic control was assessed by blood concentration of glycated hemoglobin (HbA1c). Results The prevalence of significant coronary artery stenosis (67.9% vs. 37.0%, P = 0.002) and degree of coronary atherosclerosis (Gensini score: 48.99 ± 48.88 vs. 15.07 ± 21.03, P 0.05). Conclusion Poor glycemic control negatively influences the association of endothelial dysfunction and coronary artery disease in T2DM patients.

Background Coronary artery ectasia (CAE) is an angiographic finding of abnormal coronary dilatation. Inflammation plays a major role in all phases of atherosclerosis. We investigated the relationship between CAE and serum high-sensitivity C-reactive protein (hs-CRP) and interleukin-6 (IL-6) levels to test our hypothesis that patient age is associated with the efficacy of anti-inflammatory therapy for CAE. Methods We conducted a prospective analysis of 217 patients with CAE treated at the Department of Cardiology, Shanghai East Hospital, Ji’an Campus and the Baoshan People’s Hospital, from January 1, 2015 to July 30, 2019. Baseline data of patients, including sex; age; and history of hypertension, hyperlipidemia, and diabetes, were collected from patient medical records. Study participants were grouped by age as follows: CAE-A (n = 60, age ≤ 50 years), CAE-B (n = 83, 50 years n = 74, age > 70). Additionally, there was a control (NC) group (n = 73) with normal coronary arteries. Results All patients received oral rosuvastatin therapy (10 mg, QN quaque nocte) when they were diagnosed with CAE and maintained good follow-up, with a loss rate of 0.0% at the end of the 6-month follow-up. The NC group received regular symptom-relieving treatments and rosuvastatin therapy. Of these four groups, the inflammatory markers, hs-CRP and IL-6, were significantly higher in patients with CAE than in the NCs (p P = 0.048, P = 0.025). Logistic regression analysis showed that hs-CRP (OR = 1.782, 95% CI: 1.124–2.014, P = 0.021) and IL-6 (OR = 1.584, 95% CI: 1.112–1.986, P = 0.030) were independent predictors of CAE. The inflammatory markers were higher in the CAE-A group than in the CAE-B group and higher in the CAE-B group than in the CAE-C group. Follow-up after 6 months of rosuvastatin therapy showed a significantly greater reduction in hs-CRP and IL-6 levels in the CAE-A group than in the CAE-B group, which again were greater in the CAE-B group than in the CAE-C group. Conclusions Anti-inflammatory therapy using rosuvastatin was more effective in younger CAE patients, indicating the need for early statin therapy in CAE.

Summary This paper contributes to dynamic surface asymptotic tracking for a class of uncertain nonlinear systems in strict-feedback form. By utilizing the nonlinear filters with a positive time-varying integral function, an adaptive state feedback controller is explicitly designed via a dynamic surface approach, where the compensating term with the estimate of an unknown bound is introduced to eliminate the effect raised by the boundary layer error at each step. Compared with the existing results in the literature, the proposed control scheme not only avoids the issue of “explosion of complexity” inherent in the backstepping procedure but also holds the asymptotic output tracking. Finally, simulation results are presented to verify the effectiveness of the proposed methodology.

In this study, the authors consider the problem of adaptive tracking control for a class of non-linear uncertain systems in the presence of input saturation. To tackle the effects of the non-smooth saturation non-linearity, a novel approximate saturation model is constructed, which can smoothly approximate the real saturation with arbitrarily prescribed precision. By utilising dynamic surface control approach with the modified linear filters, a robust adaptive control scheme is explicitly designed via the adding an integrator technique. The proposed controller can eliminate not only the ‘explosion of complexity’ issue inherent in the backstepping design but also the coupling terms with respect to the surface errors and the boundary layer errors. In addition, the stability analysis shows that all the resulting closed-loop signals are semi-global uniformly ultimately bounded. Finally, simulation results are presented to demonstrate the performance of the developed method.

In this article, a globally stable adaptive control strategy for uncertain strict-feedback systems is proposed within predefined neural network (NN) approximation sets, despite the presence of unknown system nonlinearities. In contrast to the conventional adaptive NN control results in the literature, a primary benefit of the developed approach is that the barrier Lyapunov function is employed to predefine the compact set for maintaining the validity of NN approximation at each step, thus accomplishing the global boundedness of all the closed-loop signals. Simulation results are performed to clarify the effectiveness of the proposed methodology.

Trabala vishnou gigantina Yang (Lepidoptera: Lasiocampidae) is a major pest that damages the sea-buckthorn, Hippophae rhamnoides. We observed and compared the feeding preferences of T. vishnou gigantina larvae on six sympatric plant species in a two-choice test. We also compared T. vishnou gigantina fitness, as measured by the following variables: larvae weight, developmental period, pupae versus adult weight, longevity, and fecundity rates. Between host and non-host plants, larvae showed a strong preference for their natural host (sea-buckthorn), followed by apricot, poplar, and willow. Caragana and locust were the least preferred plants when the natural host plant was not present. Larvae reared on sea-buckthorn possessed greater pre-pupal weight, had lower mortality, and developed more quickly into heavier pupae than either poplar-raised or willow-raised larvae. Fecundity was highest on sea-buckthorn, second highest on apricot, and lowest on poplar. Longevity (of both females and males) was not significantly different across plant species. These results clearly demonstrate that T. vishnou gigantina larvae are able to distinguish between host versus non-host plants, and that their preference translates to increased fitness. Possible, non-mutually exclusive explanations for observed preference and fitness differences include variation in required nutritional content across plant species or the presence of plant traits (morphological features or chemical metabolites) that negatively affect larval development. While the exact mechanisms are unknown, these data may be useful for the development of appropriate counter-measures to the damage caused by T. vishnou gigantina on sea-buckthorn.

Summary This paper focuses on the problem of adaptive control for uncertain nonaffine nonlinear systems. The original nonaffine systems are transformed into the augmented affine systems via adding an auxiliary integrator, which makes the explicit control design possible. By introducing a modified sliding mode filter in each step, a novel adaptive dynamic surface controller is proposed, where the ‘explosion of complexity’ problem inherent in the backstepping design is avoided. It is proven rigorously that for any initial control condition, the proposed adaptive scheme is able to ensure the semiglobal uniformly ultimately boundedness of all signals in the closed loop. An illustrative example is carried out to verify the effectiveness of the proposed approach. Copyright © 2016 John Wiley & Sons, Ltd.

This paper is concerned with the problem of universal control for a class of second order nonlinear systems with unknown dynamics. Without utilizing function approximators, a universal adaptive control scheme is developed via backstepping approach, where the system nonlinearities are adaptively compensated at each step. Based on Lyapunov stability theory, it is proven that, for any initial system condition, all the resulting closed loop signals are globally uniformly ultimately bounded. Finally, simulation results are presented to validate the effectiveness of the proposed design method.

This paper investigates the problem of output tracking for a class of nonlinear uncertain systems in strict feedback form. By utilizing the nonlinear filters with a common compensator, a robust adaptive control scheme is proposed via dynamic surface approach. Compared with the existing results in the literature, the proposed control scheme not only avoids the issue of "explosion of complexity" in the recursive procedure, but also eliminates the effects raised by boundary layer errors. Finally, a numerical example is presented to verify the effectiveness of the proposed methodology.

In this paper, the global output tracking is investigated for a class of uncertain nonlinear hysteretic systems with nonaffine structures. By combining the solution properties of the hysteresis model with the novel backstepping approach, a robust adaptive control algorithm is developed without constructing a hysteresis inverse. The proposed control scheme is further modified to tackle the bounded disturbances by adaptively estimating their bounds. It is rigorously proven that the designed adaptive controllers can guarantee global stability of the closed-loop system. Two numerical examples are provided to show the effectiveness of the proposed control schemes.

Summary This paper concerns the global output tracking for uncertain pure-feedback systems. By adding an integrator, the original systems with nonaffine-in-control are transformed into the augmented affine-in-control systems. Through a novel change of coordinates, an adaptive control scheme is proposed via backstepping approach, which eliminates the need of overparametrization. It is proven that the proposed control scheme is sufficient to ensure the global asymptotic tracking, as well as the boundedness of all the closed-loop signals. An illustrative example is provided to demonstrate the feasibility of the proposed method. Copyright © 2015 John Wiley & Sons, Ltd.

This paper deals with the problem of dynamic surface asymptotic tracking for a class of uncertain nonlinear systems preceded by a hysteresis input nonlinearity, where the hysteresis is described by the Bouc-Wen model. By utilizing the modified nonlinear filters and a positive time-varying integral function, a smooth adaptive controller is designed via dynamic surface approach, where the compensating terms with the estimate of unknown bounds are employed to eliminate the effects of given continuous functions on a certain compact, unknown hysteresis and external disturbance. It is shown that all the resulting closed loop signals are semiglobally bounded, and the output tracking error converges to zero asymptotically. Finally, simulation results are presented to validate the effectiveness of the proposed methodology.