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Both the mean contact force difference and the standard deviation of the contact force were minimised in the presented optimised design of a pantograph–catenary system for the purposes of improving of the current collection quality and the reduction of the contact wear. The non-dominated sorting genetic algorithm-II (NSGA-II) was applied to optimise the pantograph–catenary interaction system. The adopted NSGA-II algorithm was improved by avoiding repetition of FEM simulations with the duplicated input parameters and retaining only one of the duplicated results for the next generation selection. Either the catenary or the pantograph can be optimised individually by using the proposed versatile approach. In this research, the design optimisation of the catenary system was conducted first. After that, the pantograph was further optimised based on the optimised design of the catenary system. A case study indicated that the standard deviation of the contact force was reduced by 33.4% in the optimised catenary design and 39% in the optimised pantograph design, and the contact force differences were reduced by 98.3% and 99.9% in the optimised catenary design and the optimised pantograph design, respectively. Highlights Both the standard deviation of the contact force and the difference between the actual mean contact force and the ideal mean contact force are minimised in the optimisation design of a pantograph–catenary system. Either the catenary or the pantograph can be optimised separately by using the proposed versatile approach. Non-dominated Sorting Genetic Algorithm-II (NSGA-II) was improved by avoiding repetition of finite element method simulations with the same input parameter combinations and retaining only one of the same results for the next generation selection. A case study indicates that the standard deviation of the contact force can be reduced by 33.4% in the optimised catenary design and 39% in the optimised pantograph design, and the contact force difference can be reduced by 98.3% and 99.9% in the optimised catenary design and the optimised pantograph design, respectively. [ABSTRACT FROM AUTHOR]

The abuse of high beam lights dazzles the opposite drivers when the vehicles meet at night, which can easily cause traffic accidents. The existing night vision anti-halation algorithms based on different-source image fusion can eliminate halation and obtain fusion images with rich color and details. However, the algorithms mistakenly eliminate some high-brightness important information. In order to address the problem, a night vision anti-halation algorithm based on low-frequency sequence generation is proposed. The low-frequency sequence generation model is constructed to generate image sequences with different degrees of halation elimination. According to the estimated illuminance for image sequences, the proposed sequence synthesis based on visual information maximization assigns a large weight to the areas with good brightness so as to obtain the fusion image without halation and with rich details. In four typical halation scenes covering most cases of night driving, the proposed algorithm effectively eliminates halation while retaining useful high-brightness information and has better universality than the other seven advanced comparison algorithms. The experimental results show that the fusion image obtained by the proposed algorithm is more suitable for human visual perception and helps to improve night driving safety. [ABSTRACT FROM AUTHOR]

In order to address driver's dazzle caused by the abuse of high beams when vehicles meet at night, a night vision anti-halation algorithm based on image fusion combining visual saliency with YUV-FNSCT is proposed. Improved Frequency-turned (FT) visual saliency detection is proposed to quickly lock on the objects of interest, such as vehicles and pedestrians, so as to improve the salient features of fusion images. The high- and low-frequency sub-bands of infrared saliency images and visible luminance components can quickly be obtained using fast non-subsampled contourlet transform (FNSCT), which has the characteristics of multi-direction, multi-scale, and shift-invariance. According to the halation degree in the visible image, the nonlinear adaptive fusion strategy of low-frequency weight reasonably eliminates halation while retaining useful information from the original image to the maximum extent. The statistical matching feature fusion strategy distinguishes the common and unique edge information from the high-frequency sub-bands by mutual matching so as to obtain more effective details of the original images such as the edges and contours. Only the luminance Y decomposed by YUV transform is involved in image fusion, which not only avoids color shift of the fusion image but also reduces the amount of computation. Considering the night driving environment and the degree of halation, the visible images and infrared images were collected for anti-halation fusion in six typical halation scenes on three types of roads covering most night driving conditions. The fused images obtained by the proposed algorithm demonstrate complete halation elimination, rich color details, and obvious salient features and have the best comprehensive index in each halation scene. The experimental results and analysis show that the proposed algorithm has advantages in halation elimination and visual saliency and has good universality for different night vision halation scenes, which help drivers to observe the road ahead and improve the safety of night driving. It also has certain applicability to rainy, foggy, smoggy, and other complex weather. [ABSTRACT FROM AUTHOR]

Tectona grandis is a traditional Dai medicine plant belonging to the Lamiaceae family, which can be used to treat malaria, inflammation, diabetes, liver disease, bronchitis, tumors, cholelithiasis, jaundice, skin disease and as an anti-helminthic. To find more novel therapeutic agents contained in this medicinal plant, the antioxidant, anti-inflammatory and anti-diabetic activities of T. grandis methanolic extract, fractions and compounds were evaluated. In this study, 26 compounds were isolated from the leaves and branches of T. grandis. Their structures were identified based on extensive spectral experiments, including NMR, ESI-MS and comparison with published spectral data. Among them, compounds 1–2, 4–6, 9–14 and 16–22 were reported for the first time for this plant. The antioxidant activity screening results showed that compounds 5, 15 and 23 had potent antioxidant capacities, with SC50 values from 0.32 to 9.92 µmol/L, 0.92 to 1.10 mmol Trolox/L and 1.02 to 1.22 mmol Trolox/L for DPPH, ABTS and FRAP, respectively. In addition, their anti-inflammatory effects were investigated by releasing TNF-α, IL-1β and IL-6 through the use of mouse monocytic macrophages (RAW 264.7). Compounds 1, 13, 18 and 23 had the effects of reducing the expression of inflammatory factors. Compounds 13 and 18 were reported for the first time for their anti-inflammatory activities. Furthermore, the methanolic extract (ME), petroleum ether extract (PEE) and EtOAc extract (EAE) of T. grandis showed significant glucose uptake activities; compounds 21 and 23 significantly promoted glucose uptake of 3T3-L1 adipocytes at 40 µM. Meanwhile, compounds 4, 5 and 7 showed significant inhibitory activities against α-glucosidase, with IC50 values of 14.16 ± 0.34 µmol/L, 19.29 ± 0.26 µmol/L and 3.04 ± 0.08 µmol/L, respectively. Compounds 4 and 5 were reported for the first time for their α-glucosidase inhibitory activities. Our investigation explored the possible therapeutic material basis of T. grandis to prevent oxidative stress and related diseases, especially inflammation and diabetes. [ABSTRACT FROM AUTHOR]

In folk medicine, Ficus tikoua (F. tikoua) has been used to treat diabetes for a long time, but there is a rare modern pharmacological investigation for its antidiabetic effect and mechanisms. Our study aimed to evaluate its hypoglycemic effect using in vitro and in vivo experimental models and then explore the possible mechanisms. In the ethanol extracts and fractions of F. tikoua, n-butanol fraction (NBF) exhibited the most potent effect on inhibiting α-glucosidase activity (IC50 = 0.89 ± 0.04 μg/mL) and promoting glucose uptake in 3T3-L1 adipocytes. Further animal experiments showed that NBF could play an antidiabetic role by ameliorating random blood glucose, fasting blood glucose, oral glucose tolerance, HbA1c level, and islets damage in diabetic mice. Then, the activities of the five subfractions of NBF (NBF1-NBF5) were further evaluated; NBF2 showed stronger α-glucosidase inhibition activities (IC50 = 0.32 ± 0.05 μg/mL) than NBF. Moreover, NBF2 also possessed the ability to promote glucose uptake, which was mediated via P13K/AKT and AMPK pathways. This study demonstrated that F. tikoua possesses antidiabetic efficacy in vitro and in vivo and provided a scientific basis for its folk medicinal use. NBF2 might be potential natural candidate drugs to treat diabetes mellitus. It is the first time the antidiabetic activity and the potential mechanisms of NBF2 were reported. [ABSTRACT FROM AUTHOR]

In order to address the discontinuity caused by the direct application of the infrared and visible image fusion anti-halation method to a video, an efficient night vision anti-halation method based on video fusion is proposed. The designed frame selection based on inter-frame difference determines the optimal cosine angle threshold by analyzing the relation of cosine angle threshold with nonlinear correlation information entropy and de-frame rate. The proposed time-mark-based adaptive motion compensation constructs the same number of interpolation frames as the redundant frames by taking the retained frame number as a time stamp. At the same time, considering the motion vector of two adjacent retained frames as the benchmark, the adaptive weights are constructed according to the interframe differences between the interpolated frame and the last retained frame, then the motion vector of the interpolated frame is estimated. The experimental results show that the proposed frame selection strategy ensures the maximum safe frame removal under the premise of continuous video content at different vehicle speeds in various halation scenes. The frame numbers and playing duration of the fused video are consistent with that of the original video, and the content of the interpolated frame is highly synchronized with that of the corresponding original frames. The average FPS of video fusion in this work is about six times that in the frame-by-frame fusion, which effectively improves the anti-halation processing efficiency of video fusion. [ABSTRACT FROM AUTHOR]

Our research focused on the hypoglycemic capability and the possible mechanisms of extract and fractions from Polygoni Avicularis Herba (PAH) based on α-glucosidase, α-amylase inhibition assays, glucose uptake experiment, HPLC-MS analysis, and molecular docking experiment. In addition, DPPH, ABTS, and FRAP assays were used for determining the antioxidant capability. The results of total flavonoids and phenolics contents showed that ethyl acetate fraction (EAF) possessed the highest flavonoids and phenolics with values of 159.7 ± 2.5 mg rutin equivalents/g and 107.6 ± 2.0 mg galic acid equivalents/g, respectively. The results of in vitro hypoglycemic activity showed that all samples had effective α-glucosidase inhibition capacities, and EAF possessed the best inhibitory effect with IC50 value of 1.58 ± 0.24 μg/mL. In addition, n-butanol fraction (NBF) significantly promoted the glucose uptake rate of 3T3-L1 adipocytes. HPLC-MS analysis and molecular docking results proved the interactions between candidates and α-glucosidase. The results of antioxidation capacities showed that EAF possessed the best antioxidation abilities with DPPH, ABTS, and FRAP. In summary, the hypoglycemic activity of PAH might be related to the inhibition of α-glucosidase (EAF > PEF > NBF) and the promotion of glucose uptake in 3T3-L1 adipocytes (NBF). Simultaneously, the antioxidation capacity of PAH might be related to the abundant contents of flavonoids and other phenolics (EAF > PEF > NBF). [ABSTRACT FROM AUTHOR]

Traditionally, Cymbopogon citratus is used to treat a variety of ailments, including cough, indigestion, fever, and diabetes. The previous chemical and bioactive research on C. citratus mainly focused on its volatile oil. In this study, 20 non-volatile known compounds were isolated from the dried aerial part of C. citratus, and their structures were elucidated by MS, NMR spectroscopy, and comparison with the published spectroscopic data. Among them, 16 compounds were reported for the first time from this plant. The screening results for antioxidant and α-glucosidase inhibitory activities indicated that compounds caffeic acid (5), 1-O-p-coumaroyl-3-O-caffeoylglycerol (8), 1,3-O-dicaffeoylglycerol (9) and luteolin-7-O-β-D-glucopyranoside (12) had potent antioxidant capacities, with IC50 values from 7.28 to 14.81 μM, 1.70 to 2.15 mol Trolox/mol and 1.31 to 2.42 mol Trolox/mol for DPPH, ABTS, and FRAP, respectively. Meanwhile, compounds 8 and 9 also exhibited significant inhibitory activities against α-glucosidase, with IC50 values of 11.45 ± 1.82 μM and 5.46 ± 0.25 μM, respectively, which were reported for the first time for their α-glucosidase inhibitory activities. The molecular docking result provided a molecular comprehension of the interaction between compounds (8 and 9) and α-glucosidase. The significant antioxidant and α-glucosidase inhibitory activities of compounds 8 and 9 suggested that they could be developed into antidiabetic drugs because of their potential regulatory roles on oxidative stress and digestive enzyme. [ABSTRACT FROM AUTHOR]

This paper focuses on the adaptive control of robot manipulators with closed architecture and parametric uncertainty. We propose a new class of adaptive controllers via exploiting the potential as applying the forwardstepping approach and the input–output properties of an inverted form of the dynamics of robots with closed architecture. The condition that ensures the stability and convergence of the closed-loop system becomes rather moderate due to the new design and analysis, and the result presented further enhances the connection between nonlinear control theory and most industrial/commercial robotic applications. [ABSTRACT FROM AUTHOR]

This brief investigates the image-space regulation problem for visually servoed robotic systems by considering the uncertainties in the camera model and the manipulator kinematics and dynamics. By exploiting the depth-related passivity of the overall system kinematics, we first propose an adaptive dynamic controller that avoids the image-space velocity measurement by introducing a filter. In addition, we further show how to utilize the passivity property to design an adaptive kinematic control scheme, which simplifies the controller structure of the visually servoed robotic systems with the assumption that the low-level control loop can guarantee the square-integrability and boundedness of the joint velocity tracking error. We prove that both the proposed adaptive controllers can ensure the asymptotic convergence of the image-space position error. The results from a numerical simulation and extensive experimental studies illustrate the performance of the proposed adaptive image-space regulation control schemes. [ABSTRACT FROM AUTHOR]

Inflammatory response plays an important role in ischaemia reperfusion injury (IRI) through a variety of inflammatory cells. Apart from neutrophils, macrophages and lymphocytes, the role of dendritic cells (DCs) in IRI has been noticed. The study was aimed at investigating whether the high‐mobility group protein box‐1/toll like receptor 4 (HMGB1/TLR4) signalling pathway regulate the migration, adhesion and aggregation of DCs to the myocardium, induce DCs activation and maturation, stimulate the expression of surface costimulatory molecules and participate in myocardial IRI. In vivo, migration, adhesion, and aggregation of DCs was enhanced; the expression of peripheral blood DCs CD80 and CD86, myocardial adhesion molecules were increased; and the infarct size was increased during myocardial ischaemia reperfusion injury myocardial ischemic/reperfusion injury (MI/RI). These responses induced by MI/RI were significantly inhibited by HMGB1 specific neutralizing antibody treatment. Cellular experiments confirmed that HMGB1 promoted the release of inflammatory cytokines through TLR4/MyD88/NF‐κB, upregulated CD80 and CD86 expression, mediated the damage of cardiomyocytes and accelerated the apoptosis. Our results indicate that DCs activation and maturation, stimulate the expression of surface costimulatory molecules by promoting the release of inflammatory factors through NF‐κB pathway and participate in myocardial IRI. [ABSTRACT FROM AUTHOR]

Separation of the kinematic and dynamic loops is important for industrial/commercial robotic applications (i.e., for designing kinematic control schemes) and also for simplifying the controller structure, but most visual servoing algorithms in the literature, due to the lack of such separation, are hard to be justified as applied to most industrial/commercial robotic systems with a hidden inner control loop. In this brief, we investigate how passivity and nonlinear feedback are used to realize the objective of separation for visual tracking of robotic systems with parametric uncertainty and with time-varying depth, in the case of no image-space velocity measurement. We propose two new passive image-space observers that rely on the joint reference velocity rather than joint velocity, and based on these observers, we develop two adaptive controllers that do not require the image-space velocity measurement and more importantly achieve the separation of the kinematic and dynamic loops. The loop separation is achieved by resorting to the adaptive inverse-Jacobian-like control and nonlinear feedback in the controller and observer, yielding two adaptive kinematic schemes applicable to robots with a closed architecture yet admitting the design of the joint velocity (or position) command. In addition, the proposed second adaptive controller does not require inversion of the estimated depth at the expense of using a potentially-high-gain feedback. The performance of the proposed controllers is shown by numerical simulations and the implementation issues concerning the application to industrial/commercial robots are also discussed. [ABSTRACT FROM AUTHOR]

This paper investigates adaptive zero reaction motion control for free-floating space manipulators with uncertain kinematics and dynamics. The challenge in deriving the adaptive reaction null-space (RNS)-based control scheme is that it is difficult to obtain a linear expression, which is the basis of the adaptive control. The main contribution of this paper is that we skillfully obtain such a linear expression, based on which, an adaptive version of the RNS-based controller (referred to as the adaptive zero reaction motion controller in the sequel) is developed at the velocity level, taking into account both the kinematic and dynamic uncertainties. It is shown that the proposed controller achieves both the spacecraft attitude regulation and end-effector trajectory tracking. The performance of the proposed adaptive controller is shown by numerical simulations with a planar three-degree-of-freedom space manipulator. [ABSTRACT FROM AUTHOR]

Consensus problem of high-order integral multi-agent systems under switching directed topology is considered in this study. Depending on whether the agent’s full state is available or not, two distributed protocols are proposed to ensure that states of all agents can be convergent to a same stationary value. In the proposed protocols, the gain vector associated with the agent’s (estimated) state and the gain vector associated with the relative (estimated) states between agents are designed in a sophisticated way. By this particular design, the high-order integral multi-agent system can be transformed into a first-order integral multi-agent system. Also, the convergence of the transformed first-order integral agent’s state indicates the convergence of the original high-order integral agent’s state, if and only if all roots of the polynomial, whose coefficients are the entries of the gain vector associated with the relative (estimated) states between agents, are in the open left-half complex plane. Therefore, many analysis techniques in the first-order integral multi-agent system can be directly borrowed to solve the problems in the high-order integral multi-agent system. Due to this property, it is proved that to reach a consensus, the switching directed topology of multi-agent system is only required to be ‘uniformly jointly quasi-strongly connected’, which seems the mildest connectivity condition in the literature. In addition, the consensus problem of discrete-time high-order integral multi-agent systems is studied. The corresponding consensus protocol and performance analysis are presented. Finally, three simulation examples are provided to show the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the visual tracking problem for robotic systems without image-space velocity measurement, simultaneously taking into account the uncertainties of the camera model and the manipulator kinematics and dynamics. We propose a new image-space observer that exploits the image-space velocity information contained in the unknown kinematics, upon which, we design an adaptive controller without using the image-space velocity signal where the adaptations of the depth-rate-independent kinematic parameter and depth parameter are driven by both the image-space tracking errors and observation errors. The major superiority of the proposed observer-based adaptive controller lies in its simplicity and the separation of the handling of multiple uncertainties in visually servoed robotic systems, thus avoiding the overparametrization problem of the existing work. Using Lyapunov analysis, we demonstrate that the image-space tracking errors converge to zero asymptotically. The performance of the proposed adaptive control scheme is illustrated by a numerical simulation. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the flocking problem for multiple uncertain mechanical systems interacting on directed topologies. We propose an integral-sliding adaptive control to realise the objective of flocking, which gives rise to a cascade closed-loop system, and also propose a new notion – iBIBO (integral-bounded-input bounded-output) stability to characterise a new input–output property of a special class of dynamical systems, which is then used for the stability analysis of the closed-loop system. With the proposed iBIBO analysis tool and Lyapunov-like approach, we show that the proposed adaptive controller ensures the position and velocity consensus of the mechanical systems if and only if the damping is greater than certain lower bound for a given stiffness, and that the velocities of the mechanical systems converge to the weighted average of their initial values and the positions of the mechanical systems converge to the initial-states-dependent ramp trajectory. The performance of the proposed adaptive control scheme is shown by numerical simulation results. [ABSTRACT FROM PUBLISHER]

In this paper, we present a tutorial on passivity based attitude control that has been investigated over the past two decades. Both regulation control and adaptive tracking control for the attitude motion of rigid bodies are discussed under a unified passivity framework. Our attention is mainly confined to the attitude control schemes that are based on the passivity notion. Output feedback attitude control, attitude synchronization, and some open problems are also discussed. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the problem of task-space synchronisation of multiple robotic agents in the presence of uncertain kinematics and dynamics. Our control objective is to realise synchronisation without the measurements of task-space velocity. The communication topology is assumed to be directed graphs containing a spanning tree. A decentralised task-space observer with kinematic parameter updating is proposed to avoid the reliance of task-space velocity. Based on the observer, we propose the distributed adaptive synchronisation controller for two cases: (1) the leaderless consensus case and (2) the leader-follower case, where all the followers track the convex hull spanned by the virtual leaders and for each follower, it is required that there exists at least one leader that has a directed path to the follower. The asymptotic synchronisation is proved with Lyapunov analysis and input–output stability analysis tools. Simulations with multiple robotic agents are performed to show the effectiveness of the proposed schemes. [ABSTRACT FROM PUBLISHER]

Abstract: This paper investigates the flocking problem of networked nonlinear Euler–Lagrange systems with parametric uncertainties, and they are assumed to interact on directed graphs with a directed spanning tree. We propose an adaptive controller to achieve the flocking objective, and the resultant closed-loop networked system bears the cascade structure. Using a new similarity decomposition approach, a critical-characteristic-root based approach, and the input–output stability analysis, we demonstrate the convergence of the position/velocity synchronization errors among the uncertain nonlinear Euler–Lagrange agents. We also show that the velocities of the Euler–Lagrange systems converge to the weighted average velocity value. Simulation results are provided to demonstrate the performance of the proposed controller. [Copyright &y& Elsevier]

Abstract: This paper investigates the problem of synchronization of networked robotic systems with uncertainties in both kinematics and dynamics. Passivity of the robotic agents is established through adaptation to both the kinematic and dynamic uncertainties. This input–output passivation framework provides the basis for the inter-coupling inclusion between the robotic agents, even in the case of non-uniform constant communication delays. An adaptive scheme is proposed to achieve controlled synchronization of the networked robotic systems on strongly connected graphs. With a weighted Lyapunov–Krasovskii function, we show that both the task-space tracking errors and synchronization errors of the networked robotic agents converge to zero. Simulation results are provided to demonstrate the performance of the proposed control scheme. [Copyright &y& Elsevier]

Abstract: It has been about two decades since the first globally convergent adaptive tracking controller was derived for robots with dynamic uncertainties. However, not until recently has the problem of concurrent adaptation to both the kinematic and dynamic uncertainties found its solution. This adaptive controller belongs to passivity-based control. Though passivity-based controllers have many attractive properties, in general, they are not able to guarantee the uniform performance of the robot over the entire workspace. Even in the ideal case of perfect knowledge of the manipulator parameters, the closed-loop system remains nonlinear and coupled. Thus the closed-loop tracking performance is difficult to quantify, while the inverse dynamics controllers can overcome these deficiencies. Therefore, in this work, we will develop a new adaptive Jacobian tracking controller based on the inverse manipulator dynamics. Using the Lyapunov approach, we have proved that the end-effector motion tracking errors converge asymptotically to zero. Simulation results are presented to show the performance of the proposed controller. [Copyright &y& Elsevier]

Abstract: Most research so far on trajectory tracking of free-floating space manipulators has assumed that the kinematics of the space manipulator is exactly known. However, when a space manipulator picks up different tools of unknown lengths or unknown gripping points, its kinematics and dynamics change and are difficult to derive exactly. Thus, in this paper, we have proposed a passivity based adaptive Jacobian controller for free-floating space manipulators. The proposed controller consists of a transposed Jacobian feedback and a dynamic compensation term, and the parameter adaptation laws are derived by Lyapunov-like stability analysis tools. It is shown that the end-effector motion tracking errors converge asymptotically. To avoid using spacecraft acceleration, we define a new reference velocity, which is called spacecraft reference velocity. In addition, we have also conducted passivity interpretation of the proposed controller to obtain some physical insight into its properties. Simulation results are presented to show the performance of the proposed controller. [Copyright &y& Elsevier]

Most research so far on force/position tracking control of robots has assumed that the kinematics and dynamics are exactly known. In this work, we deal with force/position tracking under uncertainties arising from robot kinematics, dynamics, surface stiffness and position with an emphasis on uncertain kinematics. A robot with uncertain kinematics and dynamics in contact with a compliant surface is considered. A new adaptive Jacobian controller has been designed to cope with the uncertain robot kinematics, dynamics, environmental stiffness and position. It is shown that the controller can achieve force and position tracking via Lyapunov stability analysis. Simulation results demonstrate the performance of the controller. [ABSTRACT FROM AUTHOR]