Search Results (158)

This study aims to develop an event-triggered control strategy of grid-connected inverters, based on the linear parameter-varying (LPV) modeling approach. Regarding the changes in grid voltage, filter capacitance and inductance, and random electromagnetic interference, a stochastic LPV model for three-phase two-level inverters is established. To reduce computation burden, an event trigger with a continuous-time form is adopted to derive the state feedback controller for the LPV plant. Unlike the existing common approach to dealing with event-triggered mechanisms, a predesignated event-triggering threshold is used to determine the triggering instant of the event condition. Using parameter-dependent Lyapunov functions, sufficient conditions reliant on parameters are introduced. Based on the derived conditions, the corresponding event-triggered controllers are engineered to ensure uniform ultimate bounded stability for the resulting event-triggered LPV inverter system subject to exogenous disturbance. The simulation results are presented to confirm the efficacy of the proposed methods. Full article

This paper presents a simulation-based investigation into control strategies for mitigating the consequences of cyber-assault on the steering systems of the Maritime Autonomous Surface Ships (MASS). The study focuses on two simulation experiments conducted within the Simulink/MATLAB environment, utilizing the catamaran “Nymo” MASS mathematical model to represent vessel dynamics. Cyber-attacks are modeled as external disturbances affecting the rudder control signal, emulating realistic interference scenarios. To assess control resilience, two configurations are compared during a representative turning maneuver to a specified heading: (1) a Proportional–Integral–Derivative (PID) regulator augmented with a Least Mean Squares (LMS) adaptive filter, and (2) a Nonlinear Autoregressive Moving Average with Exogenous Input (NARMA-L2) neural network regulator. The PID and LMS configurations aim to enhance the disturbance rejection capabilities of the classical controller through adaptive filtering, while the NARMA-L2 approach represents a data-driven, nonlinear control alternative. Simulation results indicate that although the PID and LMS setups demonstrate improved performance over standalone PID in the presence of cyber-induced disturbances, the NARMA-L2 controller exhibits superior adaptability, accuracy, and robustness under adversarial conditions. These findings suggest that neural network-based control offers a promising pathway for developing cyber-resilient steering systems in autonomous maritime vessels. Full article

DNA is inherently unstable and is susceptible to damage from both endogenous sources (such as reactive oxygen species) and exogenous factors (including UV, ionizing radiation, and chemicals). The accumulation of DNA damage manifests as genetic mutations, chromosomal instability, and the stalling of DNA replication and transcription processes. Accumulated DNA damage influences apoptosis and cell cycle checkpoints, serving as one of the key triggers for the manifestation of the senescent phenotype. Both aging and cancer are associated with the accumulation of mutations in somatic cells. Disruption of cell cycle control and uncontrolled proliferation are fundamental characteristics of any cancer cell, with the majority of anticancer drugs acting as inhibitors of cyclin-dependent kinases, thereby inducing a transition of cells into a senescent state. Consequently, disturbances in the dynamics and regulation of inflammatory responses, oxidative stress, cell proliferation, DNA damage repair, and epigenetic anomalies, along with the influence of retroviruses and transposons, lead to the accumulation of senescent cells within the human body, characterized by blocked replication and cell cycle, as well as a distinct secretory phenotype. The age-related or disease-associated accumulation of these senescent cells significantly alters the physiology of tissues and the organism as a whole. Many secondary metabolites of higher plants exhibit senolytic and senomorphic activities, although most of them are not fully characterized. In this review, we will explore the principal signaling pathways in mammalian cells that govern the cell cycle and cellular senescence, with a particular emphasis on how their dynamics, expression, and regulation have been modified through the application of senotherapeutic compounds. The second section of the review will identify key target genes for the metabolic engineering, primarily aimed at enhancing the accumulation of plant secondary metabolites with potential therapeutic benefits. Lastly, we will discuss the rationale for utilizing liver cells as a model system to investigate the effects of senolytic compounds on human physiology and health, as well as how senotherapeutic substances can be leveraged to improve gene therapy approaches based on CRISPR/Cas9 and prime-editing technologies. Full article

This study aims to investigate the endogenous gibberellin levels and related genes analysis of noxious invasive weed Heracleum sosnowskyi. Genome-wide identification, phylogenetic analysis, conserved motif analysis, and gene structure characterization of GA-oxidases were performed. We analysed endogenous GAs levels and the expression of target HsGAoxs in response to GA₃ within H. sosnowskyi developing ovaries. Twenty-seven HsGAoxs genes were identified, distributed across eleven chromosomes. Phylogenetic analysis classified proteins into the HsGA20ox, C₁₉-HsGA2ox, and HsGA3ox subfamilies, facilitating functional predictions. Among the thirteen HsGA2ox protein members, there were no C₂₀-GA2ox subfamily that distinguish H. sosnowskyi from other model plant species. The analysis of gene structure and conserved motifs confirmed the phylogenetic grouping and suggested that the evolutionary pattern was maintained within these subfamilies. The observed increase in precursor and bioactive GA levels provides evidence that they play a crucial role in promoting fruit growth. Ovary phenotypes reflected the timing of peak gibberellin levels, specifically during the cell expansion period. Exogenous GA₃ treatment promoted HsGA3ox1 expression within both the central and lateral regions of the umbel ovaries. Overall, the results show that GA levels are precisely regulated by multiple HsGAox genes for stable early fruit development, and that disturbances in this stability affect fruit development. This opens up the possibility of investigating the role of GA in H. sosnowskyi fruit formation and developing measures for invasion control. Full article

This work deals with switching structured linear systems, a class of structured linear systems whose existing links between the state, input, and output variables have unknown numerical values and, in addition, are subject to change according to an exogenous, time-dependent signal. Geometric methods and computational tools developed to solve control and observation problems stated for this class of structured linear systems are presented. In particular, this work delves into the notions of invariance, controlled invariance, and conditioned invariance and focuses on their use in the statement and proof of conditions for the solvability of the disturbance decoupling problem, both by state feedback and by output feedback, and of the unknown-input state observation problem. The fundamental concepts and the main results are explained using handy examples, with visual aid provided by directed graphs. Full article

A polymer-dispersed liquid crystal (PDLC) film is a device that can transition from opaque to transparent when electrically charged. These films can be used as actuators to control light levels in response to changing natural light. However, the current state of the art for controlling PDLC films is limited to on/off functionality, and few works in the current body of literature have explored continuous control. This study develops a novel nonlinear model for PDLCs in the context of the feedback control of light. This study also demonstrates the model’s utility by comparing experimental data of a PDLC in feedback with a proportional–integral (PI) controller for disturbance rejection and tracking of a desired light setpoint. This development is motivated by the need for a smart greenhouse that can provide programmable optimized light levels for plant growth. Specifically, a light sensor is composed of a circuit with photodiodes and calibrated for the photosynthetically active radiation range. The light sensor is placed under the film, separate from an exogenous light source, allowing for feedback control to be applied. A proportional–integral type control law is selected for stiffness and the ability to eliminate steady-state error, and it is implemented using a microcontroller. An equivalent analog control effort is applied to the PDLC via a PWM voltage signal and an H-bridge type driver. Details necessary for the driving of the PDLC are presented. Open-loop identification of the nonlinear quasi-static and dynamic step-response transients of the PDLC at different control levels are presented and modeled. Finally, closed-loop experimental and simulated results are presented for both light disturbance rejection and setpoint tracking. This shows that the proposed control framework allows for continuous control of light. Full article

In this study, we developed a framework for achieving prescribed-time bipartite output consensus in nonlinear multi-agent systems by introducing a distributed observer approach. We propose a novel control protocol that utilizes a bipartite projective parameter and allows the settling time to be predetermined within a physically feasible range, independent of the system parameters and initial conditions. By using a time-varying scaling function ($\mu (t)$), the prescribed time may not depend on initial conditions and system parameters and covers more complex, nonlinear multi-agent systems. State and disturbance observers are co-designed to estimate unmeasurable states and reject external perturbations. Sufficient conditions for scenarios regarding the presence of exogenous disturbances are established by using algebraic graph theory, nonlinear system theory, Lyapunov stability, and matrix theory. Finally, numerical simulations verify the effectiveness of the designed protocol and the correctness of the proposed theorem. Full article

To address the nonlinearity and control problems of the Maglev system caused by external disturbances and internal factors of the system, this study first established a kinematic model of a single-point levitation system. Secondly, based on the nonlinear characteristics of the kinematic model, Gaussian noise was introduced into the model as input disturbance, and a neural network was used to train the constructed model. A nonlinear autoregressive model with exogenous inputs was constructed, and the Recursive Least Squares method with Forgetting Factor (RLS-FF) was used to perform parameter identification on the levitation system by combining the training data, further constructing an accurate model of the levitation system. Then, based on the accurate model of the levitation system, the backstepping method was adopted to design an adaptive controller for the levitation system, and its stability was verified. Simulation analysis was conducted on the MATLAB/Simulink platform, and comparisons were made with the LQR control method and the Fuzzy-PID control method that verified that the designed controller had a faster response speed and better self-regulation ability. At the same time, interference signals were introduced into the simulation to simulate the actual scene, and the good anti-interference ability and adaptive performance of the designed controller were further verified. Full article

Background: Pseudohypertriglyceridemia (pseudo-HTG) is a condition in patients with glycerol kinase deficiency or other disorders of glycerol metabolism, as well as in individuals with alcoholism, severe liver disease, or metabolic disturbances, and those receiving heparin therapy. Exogenous glycerol intake can also trigger this condition. However, the causes of pseudo-HTG are poorly understood, and a clinical algorithm for its diagnosing remains to be developed. Case presentation: We present the case of a 46-year-old man admitted to hospital with hypertriglyceridemia-induced severe acute pancreatitis (HTG-SAP) and type 2 diabetes mellitus. Upon admission, his plasma triglyceride (TG) level was critically high at 43.78 mmol/L (3877 mg/dL). During hospitalization, he developed acute renal insufficiency and diabetic ketoacidosis (DKA). Despite conventional lipid-lowering treatments, including extracorporeal lipoprotein apheresis, his TG levels remained elevated. The unusually clear serum led to suspicion of pseudo-HTG. A glycerol-corrected TG assay confirmed normal TG values, thereby diagnosing pseudo-HTG. Conclusions: This report presents the first confirmed case of pseudo-HTG verified through definitive glycerol kinase (GK) gene testing in a patient without glycerol kinase deficiency. We also include a review of the relevant literature and propose a clinical algorithm. The case report highlights the importance of considering pseudo-HTG in hypertriglyceridemia patients who do not respond well to the standard TG-lowering treatment. Our proposed clinical algorithm for diagnosing pseudo-HTG is potentially invaluable in clinical practice, and helps to prevent unnecessary lipid-lowering treatments for patients with pseudo-HTG. Full article

This article presents an optimal tracking controller retrofitted with a nonlinear adaptive integral compensator, specifically designed to ensure robust and accurate positioning of Vertical Take-Off and Landing (VTOL) Unmanned Aerial Vehicles (UAVs) that utilize contra-rotating motorized propellers for differential thrust generation. The baseline position controller is synthesized by employing a fixed-gain Linear Quadratic Integral (LQI) tracking controller that stabilizes position by tracking both state variations and pitch-axis tracking error integral, which adjusts the voltage to control each coaxial propeller’s speed accurately. Additionally, the baseline tracking control law is supplemented with a rate-varying integral compensator. It operates as a nonlinear scaling function of the tracking-error velocity and the braking acceleration to enhance the accuracy of reference tracking without sacrificing its robustness against exogenous disruptions. The controller’s performance is analyzed by performing experiments on a tailored hardware-in-the-loop aero-pendulum testbed, which is representative of VTOL UAV dynamics. Experimental results demonstrate significant improvements over the nominal LQI tracking controller, achieving 17.9%, 61.6%, 83.4%, 43.7%, 35.8%, and 6.8% enhancement in root mean squared error, settling time, overshoot during start-up, overshoot under impulsive disturbance, disturbance recovery time, and control energy expenditure, respectively, underscoring the controller’s effectiveness for potential UAV and drone applications under exogenous disturbances. Full article

Increasing nitrogen (N) addition induces soil nutrient imbalances and is recognized as a major regulator of soil microbial communities. However, how soil bacterial abundance, diversity, and community composition respond to exogenous N addition in nutrient-poor and generally N-limited regions remains understudied. In this study, we investigated the effects of short-term exogenous N additions on soil bacterial communities using quantitative polymerase chain reaction (PCR) and Illumina Miseq sequencing in an in situ N addition field experiment. The results showed that a low nitrogen addition increased the observed species (Sobs) of the bacterial community, and with the increased nitrogen addition, the Sobs of bacteria gradually decreased, especially the unique OTUs. The relative abundance of Proteobacteria, Actinobacteria, and Gemmatimonadetes increased with increasing nitrogen addition, whereas the relative abundance of Chloroflexi and Firmicutes decreased. Soil properties play an important role in bacterial community structure at phylum or genus levels. Short-term nitrogen addition increased the proportion of nodes from Actinobacteria and Proteobacteria in the co-occurrence network and enhanced the stability of the microbial network. Actinobacteria may play an important role in constructing the network. Our study aims to explore the effects of nitrogen addition on the diversity, composition, and structure of soil bacterial communities in nutrient-poor areas caused by ecological disturbances. Full article

Background/Objectives: Lichen planus (LP) is a chronic, recurrent mucocutaneous inflammatory disease that develops due to a disturbed immunological response triggered by endogenous and exogenous factors. To evaluate clinical presentation, demographic characteristics, and risk factors in a cohort of Polish patients with oral lichen planus (OLP). Methods: Medical records of 186 patients with OLP referred to the student outpatient clinic in Poznań University of Medical Sciences from 2013 to 2023 were analyzed in order to establish clinical presentation, patient’s demographic characteristics, and risk factors for OLP. We considered data regarding age, sex, medical history, habits, subjective complaints, clinical type, localization, histology, and treatment. Results: Patients with OLP constituted 20.1% of 887 admitted patients. Of the 186 patients with OLP, 130 (69.9%) were females and 56 (30.1%) were males. The average age at the diagnosis was 60.7 years (range 15–95 years). Only 24.2% of patients reported smoking. The most common intraoral presentation of OLP was reticular form (61.8%), followed by mixed erosive-bullous type (15%), and atrophic (6.4%). Pathologic lesions were most commonly located on buccal mucosa (89.2%) and tongue (58.6%). Subjective complaints included pain (48.4%), burning sensation (46.2%), xerostomia (25.3%), bleeding (10.2%), taste disturbance (4.8%), and excessive saliva production (3.8%), while 22.6% of OLP patients were asymptomatic. Conclusions: The most common type of OLP in Polish patients was reticular, developing mostly on the buccal mucosa and tongue. It was found most often in non-smoking middle-aged women. Subjective complaints were reported by over 77% of patients. Full article

This paper presents the constitution of a computationally intelligent self-adaptive steering controller for a lawn-mowing robot to yield robust trajectory tracking and disturbance rejection behavior. The conventional fixed-gain proportional–integral–derivative (PID) control procedure lacks the flexibility to deal with the environmental indeterminacies, coupling issues, and intrinsic nonlinear dynamics associated with the aforementioned nonholonomic system. Hence, this article contributes to formulating a self-adaptive single-neuron PID control system that is driven by an extended Kalman filter (EKF) to ensure efficient learning and faster convergence speeds. The neural adaptive PID control formulation improves the controller’s design flexibility, which allows it to effectively attenuate the tracking errors and improve the system’s trajectory tracking accuracy. To supplement the controller’s robustness to exogenous disturbances, the adaptive PID control signal is modulated with an auxiliary fuzzy-immune system. The fuzzy-immune system imitates the automatic self-learning and self-tuning characteristics of the biological immune system to suppress bounded disturbances and parametric variations. The propositions above are verified by performing the tailored hardware in the loop experiments on a differentially driven lawn-mowing robot. The results of these experiments confirm the enhanced trajectory tracking precision and disturbance compensation ability of the prescribed control method. Full article

Xenoestrogens (XEs) are a group of exogenous substances that may interfere with the functioning of the endocrine system. They may mimic the function of estrogens, and their sources are plants, water or dust, plastic, chemical agents, and some drugs. Thus, people are highly exposed to their actions. Together with the development of industry, the number of XEs in our environment increases. They interact directly with estrogen receptors, disrupting the transmission of cellular signals. It is proven that XEs exhibit clinical application in e.g., menopause hormone therapy, but some studies observed that intense exposure to XEs leads to the progression of various cancers. Moreover, these substances exhibit the ability to cross the placental barrier, therefore, prenatal exposure may disturb fetus development. Due to the wide range of effects resulting from the biological activity of these substances, there is a need for this knowledge to be systematized. This review aims to comprehensively assess the environmental sources of XEs and their role in increasing cancer risk, focusing on current evidence of their biological and pathological impacts. Full article

In this study, a finite-time disturbance observer (FTDOB) with a new structure is originally put forward for the motion tracking problem of a class of nonlinear systems subject to model uncertainties and exogenous disturbances. Compared to existing disturbance estimator designs in the literature, in which the estimation error only converges to the origin asymptotically under assumptions that the first and/or second derivatives are vanishing, the suggested DOB is able to estimate the disturbance exactly in finite time. Firstly, uncertainties (parametric and unstructured uncertainties), unknown dynamics, and external disturbances in system dynamics are lumped into a generalized disturbance term that is subsequently estimated by the proposed DOB. Based on this, a DOB-based backstepping controller is synthesized to ensure high-accuracy tracking performance under various working conditions. The stability analysis of not only the DOB but also the overall closed-loop system is theoretically confirmed by the Lyapunov stability theory. Finally, the advantages of the proposed FTDOB and the FTDOB-based controller over other DOBs and existing DOB-based controllers are explicitly simultaneously demonstrated by a series of numerical simulations on a second-order mechanical system and comparative experiments on an actual DC motor system. Full article