Control Approach Research Articles

Event-Triggered Adaptive Preassigned Finite-Time Consensus Control for Multiagent Systems With Nonlinear Faults.

This article investigates a novel neuro-adaptive barrier Lyapunov function (BLF)-based event-triggered preassigned finite-time consensus control with asymptotic tracking for the nonlinear multiagent systems. The proposed approach is designed to broaden the scope of application by considering the high-order nonstrict-feedback dynamics of each agent with dynamic uncertainties subject to external disturbances and nonaffine nonlinear faults. A neural network (NN) is employed to approximate the unknown nonlinear terms. By fusing the NNs and Butterworth low-pass filter technique, the issues arising from the nonaffine nonlinear fault are addressed. To save the communication resources, a novel dynamic event-triggered mechanism based on an enhanced switching threshold is suggested. Additionally, a novel concept called the preassigned finite-time performance function (PFTPF) is defined to improve the transient and steady-state performances as well as providing faster response. The key feature of the proposed adaptive BLF-based control based on the bound estimation method is the introduction of a smooth function with decreasing variable which not only ensures that all the signals remain bounded and the synchronization errors are restricted within the PFTPF but also guarantees that the tracking errors asymptotically converge to zero. Finally, an illustrative example is provided to verify the feasibility of the proposed control approach.

The Role of Mindfulness Meditation for the Management of Hypertension in African American Adults in the US - A Scoping Review

The prevalence of hypertension is more significant among African American adults than among individuals in other ethnic groups. Mindfulness, an ancient technique used for thousands of years, is acknowledged as a valuable tool for improving health in various ways. However, despite its traditional wisdom, there remains a gap in understanding the standalone effects of MM on hypertension control. This review aimed to discuss the role of mindfulness in managing hypertension within the African American adult population in the U. S. PubMed and Scopus were the chosen databases for this exploration. The inclusion criteria comprised papers presenting primary data studies conducted on hypertensive African American patients, specifically reporting on the independent association between mindfulness and hypertension. The exclusion criteria included nonprimary data studies and studies not primarily focused on hypertension or mindfulness. Following our search strategy, we identified a total of 32 studies. Our review incorporated five randomized controlled trials, excluding manuscripts lacking primary data, nonrandomized clinical trials, and duplicates. Within these studies, mindfulness was administered to participants through either prerecorded MP3s or guidance from trained personnel. The observed reduction in blood pressure ranged from 7.2 mmHg to 21.92 mmHg for systolic blood pressure and from null to 7.2 mmHg for diastolic blood pressure across the five studies. Notably, one study showed no change in diastolic blood pressure. The outcomes of this review can contribute to clinical practice by offering an evidence-based approach for effective hypertension control through MM. The key findings highlight the positive impact of mindfulness on blood pressure regulation and emphasize using prerecorded MP3s or trained guidance as effective mindfulness delivery methods. These insights underscore the potential significance of MM as a cost-efficient and side-effect-free approach to hypertension management.

Energy Landscape Reveals the Underlying Mechanism of Cancer-Adipose Conversion in Gene Network Models.

Cancer is a systemic heterogeneous disease involving complex molecular networks. Tumor formation involves an epithelial-mesenchymal transition (EMT), which promotes both metastasis and plasticity of cancer cells. Recent experiments have proposed that cancer cells can be transformed into adipocytes via a combination of drugs. However, the underlying mechanisms for how these drugs work, from a molecular network perspective, remain elusive. To reveal the mechanism of cancer-adipose conversion (CAC), this study adopts a systems biology approach by combing mathematical modeling and molecular experiments, based on underlying molecular regulatory networks. Four types of attractors are identified, corresponding to epithelial (E), mesenchymal (M), adipose (A) and partial/intermediate EMT (P) cell states on the CAC landscape. Landscape and transition path results illustrate that intermediate states play critical roles in the cancer to adipose transition. Through a landscape control approach, two new therapeutic strategies for drug combinations are identified, that promote CAC. These predictions are verified by molecular experiments in different cell lines. The combined computational and experimental approach provides a powerful tool to explore molecular mechanisms for cell fate transitions in cancer networks. The results reveal underlying mechanisms of intermediate cell states that govern the CAC, and identified new potential drug combinations to induce cancer adipogenesis.

Advanced Nanotechnological Approaches for Biofilm Prevention and Control

Biofilm-associated infections present a significant challenge in modern medicine, primarily due to their resilience and resistance to conventional treatments. These infections occur when bacteria form biofilms, protective layers formed by bacterial communities, which are notoriously resistant to traditional antibiotics on surfaces such as medical implants and biological surfaces, making eradication with standard antibiotics difficult. This resilience leads to persistent infections, imposing a substantial economic burden on healthcare systems. The urgency to find alternative treatments is critical as current methods are insufficient and costly. Innovative approaches, such as nanotechnology-based therapies, offer promising alternatives by targeting biofilms more effectively and reducing the need for invasive procedures. Nanocarriers hold significant promise in the fight against biofilm-associated infections. Nanocarriers can penetrate biofilms more effectively than conventional treatments, delivering higher concentrations of antibiotics or other antimicrobial agents precisely where they are needed. This targeted approach not only enhances the efficacy of treatments but also minimizes potential side effects. The development of nanocarrier-based therapies is crucial for overcoming the limitations of current treatments and ultimately improving patient outcomes and reducing the economic burden of biofilm-associated infections on healthcare systems. In this review, nanotechnology-based systems, their characteristics, limitations, and potential benefits are explored to address biofilms-related infections. Additionally, biofilm evaluation models and the tests necessary for the preclinical validation of these nanosystems to facilitate their clinical application are addressed.

Mechanisms of electromagnetic field control on mineral scaling in brackish water reverse osmosis: Combined homogenous and heterogeneous nucleation

Electromagnetic field (EMF) treatment has emerged as a promising approach for scaling control due to its cost-effectiveness, simplicity, and low energy consumption. However, there is a limited understanding of the mechanisms by which applied EMF impacts mineral scaling in reverse osmosis (RO) systems. This has led to inconclusive and varied results and uncertainties regarding its effectiveness. This study elucidates the impacts of EMF on homogenous and heterogeneous nucleation and membrane performance during RO desalination of different feedwaters. Our results reveal that EMF exhibits greater efficacy in treating near-saturated water (SI∼0), especially when coupled with extended hydraulic flushing (HF). For saturated brackish water desalination, heterogeneous scaling predominantly occurs on membrane surfaces, with the effectiveness of EMF in inhibiting scaling primarily attributed to the hydration effect. In supersaturated solutions, EMF promotes bulk precipitation due to the magnetohydrodynamic effect, quickly blocking membrane pores. Thus, when the saturation reaches a certain high level during RO desalination, magnetohydrodynamic EMF effects can accelerate flux decline caused by homogeneous scaling. This work provides an efficient method for predicting EMF efficiency, emphasizing the importance of saturation conditions and HF cleaning duration in determining membrane performance, suggesting these show promise for improving undersaturated or near-saturated feedwater desalination via RO.

Unified bounded potential function approach for multi-hovercraft connectivity-maintaining and formation maneuvering control without acceleration measurement

This paper addresses the distributed leader–follower connectivity-maintaining and formation maneuvering control issue for underactuated multi-hovercraft without acceleration measurement. Firstly, a novel time-varying offset term is introduced into the position vector, which transforms the motion equation of the hovercraft into a fully actuated form. In addition, an unified bounded potential function strategy is proposed to simultaneously achieve connectivity-maintaining and formation maneuvering error stabilization without the need to design additional formation error stability terms in the controller. Then, in the absence of dynamic leader acceleration measurement, a distributed variable structure robust term is introduced into the bounded formation maneuvering control protocol, which resists entirely the influence of unknown acceleration on the system. The proposed protocol was rigorously analyzed using the Lyapunov theory. Finally, simulation results validate the effectiveness of the proposed control protocol.

Population genomic evidence of a putative ‘far-west’ African cryptic taxon in the Anopheles gambiae complex

The two main Afrotropical malaria vectors - Anopheles coluzzii and An. gambiae – are genetically distinct and reproductively isolated across West Africa. However, populations at the western extreme of their range are assigned as “intermediate” between the two species by whole genome sequence (WGS) data, and as hybrid forms by conventional molecular diagnostics. By exploiting WGS data from 1190 specimens collected across west Africa via the Anopheles gambiae 1000 Genomes network, we identified a putative taxon in the far-west (provisionally named Bissau molecular form), which did not arise by admixture but rather may have originated at the same time as the split between An. coluzzii and An. gambiae. Intriguingly, this taxon lacks insecticide resistance mechanisms commonly observed in the two main species. These findings lead to a change of perspective on malaria vector species in the far-west region with potential for epidemiological implications, and a new challenge for genetic-based mosquito control approaches.

Method for Producing Columnar Ice in Laboratory and Its Application

This study presents the design of a small open-circuit wind tunnel for laboratory use and a method for preparing columnar ice. The ice formation process was analyzed in terms of temperature and ice thickness variations under varying environmental temperatures and wind speeds. Observations revealed that as wind speed increased, the grain size of the columnar ice decreased. Key findings include the following: (1) the selection and validation of two cubic arcs for the wind tunnel contraction section, achieving an acceleration ratio of 6.7–6.8 and stable wind speeds of 1–10 m/s; (2) real-time temperature monitoring indicated rapid cooling before freezing and slower cooling post-freezing, with lower ambient temperatures and higher wind speeds accelerating the icing process; (3) the −1/2 power of grain size was found to be positively correlated with wind speed; and (4) the method’s feasibility for studying mechanical properties of polar columnar ice was confirmed. This technique offers a controlled approach for producing columnar ice in the laboratory, facilitating comprehensive research on ice properties and providing a foundation for future studies on the mechanical behavior of ice under windy polar conditions.

A decentralized control approach in hypergraph distributed optimization decomposition cases

We study the main decomposition approaches (primal, dual and primal–dual) for a distributed optimization problem from a dynamical system perspective where the couplings among the variables of the optimization problem are described by an undirected, unweighted hypergraph. We conduct stability analysis for the respective dynamical systems of the decomposition cases by using non linear decentralized control theoretic techniques and spectral properties of the respective communication matrices, i.e., the incidence and the Laplacian matrices of the hypergraph. Finally, we provide numerical simulations under a specific coalitional setting that demonstrate the superiority of the hypergraph compared to its respective graph analogue, the clique expansion graph, for the given decomposition algorithms in terms of convergence rate and information transmission efficiency.

A comprehensive approach to continuous quality improvement of massive transfusion by developing key performance indicators.

To develop key performance indicators (KPI) for use in quality assessment of our institutional goal-directed massive transfusion (GDMT). A team comprising our transfusion and emergency medicine departments carried out a cross-sectional data analysis of GDMT in adult patients from January 2021 to December 2022. The study was rooted in the Define, Measure, Analyse, Improve, Control (DMAIC) approach. Features of KPIs were (a) importance, (b) scientific soundness and (c) feasibility. Study parameters were defined and analysed using measures of central tendencies and benchmark comparison. Ninety-two massive transfusion events occurred and 1405 blood components were used. Trauma was the leading cause, followed by postpartum haemorrhage and upper gastrointestinal bleeding. Appropriate GDMT activation was observed only in 43.47% of events. The turnaround time (TAT) was within the benchmark in 85.8% of events with an average of 16 ± 10 min. The average utilization of blood components was 20.5 (interquartile range [IQR] = 11.3) in the appropriate group and 5.5 (IQR = 4.25) in the inappropriate group with a wastage rate of 3.5%. Duration of activation was 6.19 ± 4.59 h, and the adherence to thromboelastography was 66.3%. Overall mortality was 45.65%, and the average duration of hospital stay was 6.1 ± 5.9 days. The KPIs developed were easy to capture, and the analysis provided a comprehensive approach to the quality improvement of the GDMT protocol.

Building 3D Crosslinked Graphene-MXene Nanoarchitectures Decorated with MoS2 Quantum Dots Enables Efficient Electrocatalytic Hydrogen Evolution.

Although MoS2 quantum dots with abundant edge sites have been regarded as promising eletrode materials for the hydrogen evolution reaction (HER), their electrocatalytic capacity still requires improvements in actual applications. Herein. we demonstrate a controllable and robust bottom-up approach to build 3D crosslinked graphene-Ti3C2Tx MXene frameworks decorated with MoS2 quantum dots (MQD/RGO-MX) via a convenient co-assembly process. The novel structural design gives the MQD/RGO-MX nanoarchitectures a series of superior textural attributes, including 3D interconnected networks, continuous meso- and macropores, well-dispersed quantum dots, ameliorative electronic configuration, and excellent electrical conductivity. Accordingly, the resulting hybrid nanoarchitectures express superior electrocatalytic properties in terms of a low onset potential of only 45 mV, a small Tafel slope of 61 mV dec-1 as well as a long service life towards the HER, which make it quite competitive against bare MoS2 quantum dots, MXene as well as binary MQD/RGO and MQD/MXene electrocatalysts.

Vehicle Stability Control Based on Vehicle Motion State and Tire Force Estimation

The direct yaw moment control system is able to greatly enhance the vehicle stability when driving on challenging road surfaces. This paper introduces a direct control approach for managing the vehicle yaw moment, utilizing terminal sliding mode control and a Square Root Cubature Kalman Filter (SRCKF). Initially, the longitudinal and lateral forces acting on the vehicle's tires are estimated through a sliding mode observer. Subsequently, the SRCKF algorithm and the four-wheel tire force are employed to accurately estimate the yaw rate and sideslip angle. Based on these estimations, additional yaw moments are determined using the terminal sliding mode control algorithm, and a combined control of yaw rate and sideslip angle is achieved through a threshold method. A rule-based braking force distribution strategy is then implemented to ensure vehicle stability control. Simulation results demonstrate that the tire force estimations from the sliding mode observer and the vehicle yaw rate and sideslip angle estimations from the SRCKF algorithm closely align with the output results from Carsim, with an error margin of less than 15%. The braking force distribution strategy, based on the direct yaw moment control using the terminal sliding mode algorithm, effectively tracks the desired yaw rate and sideslip angle.

An Improved Collaborative Control Scheme to Resist Grid Voltage Unbalance for BDFG-Based Wind Turbine

This article presents an improved collaborative control to resist grid voltage unbalance for brushless doubly fed generator (BDFG)-based wind turbine (BDFGWT). The mathematical model of grid-connected BDFG including machine side converter (MSC) and grid side converter (GSC) in the αβ reference frame during unbalanced grid voltage condition is established. On this base, the improved collaborative control between MSC and GSC is presented. Under the control, the control objective of the whole BDFGWT system, including canceling the pulsations of electromagnetic torque and the unbalance of BDFGWT’s total currents, pulsations of BDFGWT’s total powers are capable of being realized; therefore, the control capability of BDFGWT to resist unbalanced grid voltage is greatly improved. Moreover, improved single-loop current controllers adopting PR regulators are proposed for both MSC and GSC where the sequence extractions for both MSC and GSC currents are not needed any more, and hence the proposed control is much simpler. In addition, the transient characteristics are also improved. Moreover, in order to achieve the decoupling control of current and average power, current controller also adopts the feedforward control approach. Case studies for a two MW BDFGWT system are implemented, and the results verify that the presented control is capable of effectively improving the control capability for BDFGWT to resist grid voltage unbalance and exhibit good stable and dynamic control performances.

Synchronization Control of Complex Spatio-Temporal Networks Based on Fractional-Order Hyperbolic PDEs with Delayed Coupling and Space-Varying Coefficients

This paper studies synchronization behaviors of two sorts of non-linear fractional-order complex spatio-temporal networks modeled by hyperbolic space-varying PDEs (FCSNHSPDEs), respectively, with time-invariant delays and time-varying delays, including one delayed coupling. One distributed controller with space-varying control gains is firstly designed. For time-invariant delayed cases, sufficient conditions for synchronization of FCSNHSPDEs are presented via LMIs, which have no relation to time delays. For time-varying delayed cases, synchronization conditions of FCSNHSPDEs are presented via spatial algebraic LMIs (SALMIs), which are related to time delay varying speeds. Finally, two examples show the validity of the control approaches.

Novel composite of nano zinc oxide and nano propolis as antibiotic for antibiotic-resistant bacteria: a promising approach

This study proposes an innovative approach to combat the escalating threat of antibiotic resistance in bacteria by introducing a novel ZnO-propolis nanocomposite (ZnO-P NCs). The overuse of antibiotics, particularly during events like the COVID-19 pandemic, has intensified bacterial resistance, necessitating innovative solutions. The study employs a cost-effective and controllable biosynthesis method to produce ZnO nanoparticles (ZnO-NPs), with propolis extract crucially contributing to the reduction and stabilization of Zn2+ ions. A biodegradable nano-propolis matrix is then created by incorporating ZnO-NPs, forming the ZnO-P NCs. Structural stability is confirmed through FT-IR and Zeta potential analysis, while nanoscale properties are validated via TEM, SEM, and XRD analyses. The antimicrobial efficacy of various substances, including propolis, nano propolis, ethanolic propolis extract, ZnO-NPs, and ZnO-P NCs, is assessed against Gram-negative and Gram-positive bacteria, alongside a comparison with 28 antibiotics. Among the bacteria tested, Pseudomonas aeruginosa PAO1 ATCC15692 was more sensitive (40 mm) to the biosynthesized nanocomposite ZnO-P NCs than to ZnO-NPs (38 mm) and nanopropolis (32 mm), while Escherichia coli was resistant to nanopropolis (0 mm) than to ZnO-NPs (31 mm), and ZnO-P NCs (34 mm). The study reveals a synergy effect when combining propolis with green-synthesized ZnO-NPs in the form of ZnO-P NCs, significantly improving their efficiency against all tested bacteria, including antibiotic-resistant strains like E. coli. The nanocomposite outperforms other materials and antibiotics, demonstrating remarkable antibacterial effectiveness. SEM imaging confirms the disruption of bacterial cell membranes by ZnO-NPs and ZnO-P NCs. The study emphasizes the potential applications of ZnO-NPs integrated into biodegradable materials and underscores the significance of the zinc oxide-propolis nanocomposite in countering antimicrobial resistance. Overall, this research offers a comprehensive solution to combat multidrug-resistant bacteria, opening avenues for novel approaches in infection control.

Complete genome sequence provides information on quorum sensing related spoilage and virulence of Aeromonas salmonicida GMT3 isolated from spoiled sturgeon

Foodborne bacteria can pose a threat to the public health due to their spoilage and virulence potential, which can be regulated by quorum sensing (QS) system. In the study, we isolated a spoilage bacteria strain Aeromonas salmonicida GMT3 from refrigerated sturgeon. The complete genome of A. salmonicida GMT3 was sequenced, and the QS related genes were assigned. QS signal molecules N-acyl-homoserine lactones (AHLs) and AI-2 were detected. Genes regulating the spoilage-related metabolic pathways, including protease and lipase secretion, amines metabolism, sulfur metabolism, motility and biofilm formation were analyzed. Furthermore, genes encoding for several virulence factors, e.g. hemolysin, aerolysin, type II secretion system (T2SS), type VI secretion system (T6SS), antibiotic and multidrug resistance were also identified. In addition, the spoilage and virulence phenotypes associated with QS including protease, swimming and swarming activity, biofilm and hemolytic activity were detected. This study provided new insights into spoilage and virulence mechanisms correlated with QS of A. salmonicida GMT3, which might promote development of new approaches for spoilage and virulence control based on QS target.

Neural Network-based Adaptive Finite-time Control for 2-DOF Helicopter Systems with Prescribed Performance and Input Saturation

In this study, we propose an adaptive neural network (NN) control approach for a 2-DOF helicopter system characterized by finite-time prescribed performance and input saturation. Initially, the NN is utilized to estimate the system’s uncertainty. Subsequently, a novel performance function with finite-time attributes is formulated to ensure that the system’s tracking error converges to a narrow margin within a predefined time span. Furthermore, adaptive parameters are integrated to address the inherent input saturation within the system. The boundedness of the system is then demonstrated through stability analysis employing the Lyapunov function. Finally, the effectiveness of the control strategy delineated in this investigation is validated through simulations and experiments.

Torsional vibration analysis and fuzzy adaptive PID control optimization of underwater vector propulsion shaft systems

To examine the torsional vibration of vector propulsion shaft system (VPSS), a four-degree-of-freedom vibration model of the VPSS is established by concentrated mass approach, and the torsional vibration differential equation of the VPSS is deduced based on the Lagrange approach. The vibration differential equations is addressed numerically applying the Runge-Kutta algorithm to investigate the effect of various working shaft angles β on the free and forced vibration of the VPSS under the excitation conditions. To further reduce the torsional vibration amplitude and avoid fatigue damage of the system, and considering the nonlinear relationship within the system, this study develops a fuzzy adaptive PID approach to control the VPSS. The results show that the maximum torsional vibration amplitude of the VPSS is reduced by more than 70% and the transient response time is shortened by more than 90% with this control approach, which effectively reduces the torsional vibration amplitude of the VPSS and thereby significantly improves the safety performance of the underwater vehicle. This may provide technical references for the vibration control theory of the VPSS as well as engineering applications.

A novel reduced-order model reference adaptive control approach with high-frequency oscillation suppression

High-frequency oscillations may occur in the control signal when the adaptive gain is too large, which will adversely affect the robustness of the model reference adaptive control (MRAC) law and potentially induce system instability. To tackle this challenge, we introduce a reduced-order MRAC approach based on a modified scalar update law that includes a modification term to filter out high-frequency content for the multi-input multi-output (MIMO) nonlinear dynamical systems. This modification significantly reduces the high-frequency oscillations, allowing a controller with a high adaptive gain to achieve fast adaptation. In addition, with this reduced-order adaptive control approach, only two parameters need to be updated online, thus substantially reducing the overall computation burden. Furthermore, we demonstrate that the proposed reduced-order MRAC approach guarantees the Lyapunov asymptotic stability of the system error dynamics. Simulation results are conducted to validate the electiveness of the proposed method.

Surface with wettability gradient — A novel approach for crystallization fouling control on the horizontal falling film flow

To manage scaling on heat transfer surfaces, using chemical-based antifouling treatments takes a toll on the environment, and related maintenance costs are significant. A unique and environmentally friendly scale mitigation strategy is developed in this work. By manipulating the scale layer distribution using surface wettability gradients, stronger flow shear and weaker scaling adhesion are achieved, facilitating self-cleaning process. Experimental work utilizes a horizontal-tube falling-film evaporator to mimic multiple-effect distillation process. A millimetric wettability pattern – alternating hydrophilic and hydrophobic regions – is created by coating stainless steel tubes. The results show scale layers (calcium carbonate) were either thicker in hydrophilic regions and thinner in hydrophobic regions or had approximately uniform thickness in both regions but cracks in scale layers near wettability boundaries. Scale layers wash-off with flow is observed on patterned tubes, demonstrating self-cleaning process. In contrast to persistent deterioration in overall HTC (heat transfer coefficient) for baseline tube (77 % of initial HTC after 192 h), HTC on patterned tubes initially increases due to surface wetting effects, then maintains roughly constant (15 % higher than that of baseline after 192 h) along with lower scale mass. This work provides a novel scaling control method, a potential “green” alternative to current industry scale-control practices.