Fault-tolerant controller design based on adaptive backstepping for tower cranes with actuator faults.

Due to the widespread application and significant investment required for a single crane, there is an increased emphasis on crane safety and service life. Fault-tolerant control as an effective solution to unexpected faults has been widely studied recently. However, most fault-tolerant control methods require redundant actuators or a complex design process, which is unsuitable for the tower crane. Following these problems, a fault-tolerant controller based on an adaptive backstepping technique is proposed. Firstly, the system states are reconstructed and written as a cascade system. Secondly, a fixed-time convergence optimized backstepping controller is proposed to achieve smooth control of the tower crane without generating sudden or abrupt values. Then, an adaptive approach has been proposed to update fault parameters for the crane system in case of a sudden fault occurrence. Finally, after conducting comparison tests, it has been determined that the proposed controller not only performs exceptionally well in terms of position accuracy and swing elimination, but also maintains a satisfactory control performance when faced with sudden faults.

Reverse knowledge transfer in digital era and its effect on ambidextrous innovation: A simulation based on system dynamics.

Knowledge transfer plays a prominent role in fostering innovation among multinational corporations (MNCs), however, the exploration of reverse knowledge transfer in today's digital era remains insufficient. Therefore, we explore the impact of reverse knowledge transfer on ambidextrous innovation and the process mechanism against the backdrop of digital technology. A system dynamics model of reverse knowledge transfer is constructed from three aspects: knowledge acquisition, knowledge absorption and knowledge application. Our simulation results indicate that the dual embeddedness of multinational R&D centers promotes knowledge acquisition and absorption, enhances the knowledge base of parent companies, and facilitates ambidextrous innovation. In particular, the application of digital technology further promotes the process through knowledge absorption, with the long-term impact more pronounced. This study not only enriches the literature on reverse knowledge transfer but also expands the application of digital technology in the field of MNCs' innovation.

The mechanisms of aluminum-induced immunotoxicity in chicks.

Aluminum (Al) is a ubiquitous environmental pollutant representing a significant global health hazard to human and animal health, including chicks. Al toxicity causes oxidative stress, leading to tissue injury, and consequently causes various diseases. NRF2 signaling is vital for protecting cells against oxidative stress. Nuclear xenobiotic receptors are activated by exogenous toxins, thereby inducing the transcription of cytochrome P450 enzyme systems (CYP450s) isoforms involved in xenobiotic metabolism and transport. However, little is known about Al-induced oxidative stress, nuclear xenobiotic receptors and fibrosis in chicks and the mechanisms involved. In this study, male chicks were treated with 0 mg/kg and 500 mg/kg Al2(SO4)3 to evaluate the mechanisms for Al-induced immunotoxicity. Histopathology revealed pathological injury, fibrin aggregation, disruption of the Nuclear Xenobiotic Receptors, and alteration of CYP450s homeostasis in Al-treated chicks due to oxidative stress. Notably, regulation of the NRF2 pathway and CYP450s and fibrosis-related genes was found to play a vital role in inhibiting immunotoxicity. This study provides new insights regarding the mechanisms of Al-induced immunotoxicity, including activation of the nuclear xenobiotic receptors, triggering oxidative stress, and altering the homeostasis of CYP450s in chicks. Further, it provides a theoretical basis for controlling Al exposure and highlights the importance of further studying its mechanisms to provide additional information for formulating preventive measures.

Adaptive-back-stepping-based controller design for double-pendulum rotary cranes.

The operating process of rotary crane is often very complicated and there are many unpredictable conditions, such as the condition of the load sway around the hook, which will undoubtedly make the sway characteristics analysis of the system and the controller design become more difficult. In addition, for the purpose of decreasing the complexity of controller design, traditional control methods often perform model linearization processing operation, which can reduce the robustness of the system to a certain extent (when the parameters of the crane are unknown or there are external disturbances, the control capability of traditional control methods will be largely degraded). Based on the above, this paper first uses kinematic analysis to derive rotary crane model, and then proposes a nonlinear controller based on adaptive back-stepping method to achieve pendulum elimination and boom positioning. Then the stability of the system is proved by Lyapunov Lemmas. Finally, the performance of the system is verified by comparing the experimental results of different methods.

Fumonisin B1 promotes germ cells apoptosis associated with oxidative stress-related Nrf2 signaling in mice testes.

Fumonisins (FBs) are widespread Fusarium toxins commonly found in corn. This study aimed to establish the mechanism of oxidative stress via the Nrf2 signaling pathway associated with FB1-induced toxicity in mice testis. Male mice were fed with 5 mg/kg FB1 diet for 21 or 42 days, the expression of inflammatory related genes, apoptosis related genes and Nrf2 pathway genes were detected by RT-qPCR, Western blot and immunohistochemical. Furthermore, Sertoli cell was treatment with FB1. Cell viability was measured by CCK8 assay, ROS level and apoptosis related genes were detected by immunofluorescence staining. The results showed that FB1 had toxic effects on testis, which could increase the ROS level of Sertoli cells, affect the Keap1-Nrf2 pathway related factors, destroy the oxidative balance of testis, lead to the occurrence of inflammation and the initiation of apoptosis, and finally destroy the testicular tissue structure and affect the formation of sperm.

Antagonistic Effect of Selenium on Fumonisin B1 Promotes Neutrophil Extracellular Traps Formation in Chicken Neutrophils.

Neutrophils are an important component of the innate immune system, and one of their defense mechanisms, neutrophil extracellular traps (NETs), is a hot topic of the current research. This study explored the effects of fumonisin B1 (FB1) on chicken neutrophil production of NETs and its possible molecular mechanism of action. Scanning electron microscopy and fluorescence microscopy were used to observe morphological changes in neutrophils, and a fluorescence microplate reader was used to detect reactive oxygen species (ROS) and extracellular DNA release from neutrophils. Quantitative PCR (qPCR) and western blot were used to determine the expression levels of selenoproteins. The results indicate that FB1 inhibited the zymosan-induced formation of NETs in chicken neutrophils by preventing ROS burst and histone H3 (H3) and neutrophil elastase (NE) release. Moreover, the mRNA expression levels of glutathione peroxidase (GPX), thioredoxin reductase (TXNRD), and deiodinase (DIO) were downregulated in the FB1 group. The protein expression levels of GPX1, GPX2, GPX3, DIO3, and TXNRD1 were consistent with the changes in their gene expressions, suggesting an abnormal selenoprotein expression in response to the toxic effects of FB1. Conversely, selenium (Se) supplementation reduced the toxic effects of FB1 and restored the NETs formation, indicating that Se can be used as a potential drug to prevent and control FB1 toxicity in livestock farming.

Precision-positioning adaptive controller for swing elimination in three-dimensional overhead cranes with distributed mass beams.

As a type of dispensable transport tool, overhead cranes are extensively applied in large industrial sites to transport containers and goods due to their extraordinary convenience and efficiency. However, various transport requirements and working environments may cause some adverse effects for overhead crane control. In particular, in some transport tasks, distributed-mass beams (DMB) are required to be transported smoothly to a specific position. Hence, most existing controllers designed for crane systems with point-mass payload (PMP) cannot meet the control requirements. For example, controllers designed for crane systems with PMP do not consider the moment of inertia of DMB, thus, the residual payload swing caused by the moment of inertia cannot be completely suppressed, which may cause safety risks. Additionally, due to various working environments, inaccurate estimation of frictions can result in errors in positioning. To solve the above issues, this paper conducts the dynamic analysis of three-dimensional (3-D) overhead crane systems with DMB and designs an improved adaptive controller which can provide favorable control for state variables. In particular, the proposed update laws can compensate for the uncertainties of crane systems. Based on a tracking trajectory, the trolley and guide rail can both reach the preset position, and the swing angles are also well eliminated throughout the transport process. The stability of the control system is proven theoretically, and the performance of the proposed controller is verified by comparative experiments.

Enhanced-coupling nonlinear controller design for load swing suppression in three-dimensional overhead cranes with double-pendulum effect.

To date, most control strategies have been designed for the two-dimensional and three-dimensional overhead crane systems with the single pendulum effect. In fact, three-dimensional overhead crane systems often exhibit the double-pendulum effect in practical applications, which is more controlled than the general single-pendulum crane, and also makes the controller design more challenging. This paper proposes a new nonlinear control strategy that enhances the coupling between the trolley speed and the swing angle components. Specifically, we devise a new energy-like function by introducing two generalized signals that can reflect the trolley speed and the hook and load swing angle components. This strategy greatly improves the effectiveness of the transient control process. Meanwhile, the asymptotic stability of the closed-loop system is not only guaranteed, but also the desired position of the trolley and swing angle suppression are achieved using the control strategy.

Transportation and swing reduction for double-pendulum tower cranes using partial enhanced-coupling nonlinear controller with initial saturation.

Achieving both jib and trolley positioning and swing reduction become more difficult when tower cranes appear double-pendulum characteristic in dynamic. Moreover, in actual applications, the initial output value of actuators is usually physically constrained and the model uncertainties and external disturbances always exist. To solve these problems, a partial enhanced-coupling nonlinear controller with initial saturation is designed and analyzed by Lyapunov technique and LaSalle's invariance theorem. The control performance and strong robustness are severally verified by lots of simulations.

Assessment of ionic homeostasis imbalance and cytochrome P450 system disturbance in mice during fumonisin B1 (FB1) exposure.

Fumonisin B1 (FB1) is a mycotoxin frequently found in agricultural commodities, and poses a considerable risk for human and animal health. The aim of this study was to investigate the toxic effect of FB1 in mice intestine. Male Kunming mice (n = 40) were treated with FB1 diet for 42 days. Histopathological and biochemical analyses, including ion concentrations, transcription of ATPase subunits and mRNA expression of cytochrome P450s (CYP450s) analyses were performed on duodenum, cecum and colon of mice. The results revealed that FB1 caused histological alterations, including partial shedding of villous epithelial cells and inflammatory cell infiltration. Furthermore, a significant change in Na+, K+ and Ca2+ in serum, and the mRNA expression of ATPase subunits and CYP450s in intestinal tracts were observed in FB1-exposed mice. Our results suggested that FB1 exposure induce histopathological injury via disrupting CYP isoforms transcription and triggering ion homeostasis imbalance in mice intestinal tracts.

Load swing rejection for double-pendulum tower cranes using energy-shaping-based control with actuator output limitation.

For the controller design of tower cranes, the swing of load is always regarded the crane as a single-pendulum model, however in practical applications, such as when the hook mass can not be ignored, the tower crane dynamic system presents a double-pendulum nature. In this case, the dynamic characteristics analysis and controller design for such cranes becomes more complicated. In addition, many researches do not take into account the real situation of the actuator, that is, in actual tower cranes, the output torque/force can not be infinite due to the actual design constraints of the actuator. When the output torque reaches the limit value in some cases, the control performance is greatly reduced. According to the above, after simplifying the tower crane dynamic model, this paper presents a nonlinear controller based on energy-shaping to solve the above problems. The stability of the closed-loop system is proved by the Lyapunov technique and LaSalle's invariance theorem. Under a large number of simulation results, the proposed controller has good control performance and robustness.

Label-free quantitative detection of protein using macroporous silicon photonic bandgap biosensors.

A label-free biosensor was demonstrated using macroporous silicon (pore size >100 nm) one-dimensional photonic band gap structures that are very sensitive to refractive index changes. In this study, we employed Tir-IBD (translocated Intimin receptor-Intimin binding domain) and Intimin-ECD (extracellular domain of Intimin) as the probe and target, respectively. These two recombinant proteins comprise the extracellular domains of two key proteins responsible for the pathogenicity of enteropathogenic Escherichia coli (EPEC). The optical response of the sensor was characterized so that the capture of Intimin-ECD could be quantitatively determined. Our result shows that the concentration sensitivity limit of the sensor is currently 4 microM of Intimin-ECD. This corresponds to a detection limit of approximately 130 fmol of Intimin-ECD. We have also investigated the dependence of the sensor performance on the Tir-IBD probe molecule concentration and the effect of immobilization on the Tir-IBD/Intimin-ECD equilibrium dissociation constant. A calibration curve generated from purified Intimin-ECD solutions was used to quantify the concentration of Intimin-ECD in an E. coli BL21 bacterial cell lysate, and results were validated using gel electrophoresis. This work demonstrates for the first time that a macroporous silicon microcavity sensor can be used to selectively and quantitatively detect a specific target protein with micromolar dissociation constant (Kd) in a milieu of bacterial proteins with minimal sample preparation.

Electrical and thermal modulation of silicon photonic bandgap microcavities containing liquid crystals.

Electrical and thermal modulation of porous silicon microcavities is demonstrated based on a change in the refractive index of liquid crystals infiltrated in the porous silicon matrix. Positive and negative anisotropy liquid crystals are investigated, leading to controllable tuning to both longer and shorter wavelengths. Extinction ratios greater than 10 dB have been demonstrated. Larger attenuation can be achieved by increasing the Q-factor of the microcavities.