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Realization of planar tetracoordinate arrangements of nitrogen atoms is challenging because their preference for localized bonding (caused by its high electronegativity) makes them typically tricoordinate. This is especially true for the more electronegative oxygen atoms. Herein, we computationally designed two clusters NBe4H4− and OBe4H4; they contain a planar tetracoordinate nitrogen (ptN) and planar tetracoordinate oxygen (ptO) atom, respectively. Remarkably, the former is a dynamically stable global minimum, while the latter is not. The bonding analysis proves that planar tetracoordination in NBe4H4− favors over tricoordination because of the presence of multicenter delocalized bonds. In contrast, the planar tricoordination dominates due to its weak delocalized bonding ability of oxygen in the OBe4H4 cluster. Moreover, the 6σ/2π double aromaticity due to multicenter delocalized bonds allows the NBe4H4− cluster to obtain additional stability. This cluster is a promising synthetic due its dynamic and thermodynamic stability. [ABSTRACT FROM AUTHOR]

The dynamic response of dielectric elastomers is widely used in many functional devices, but current research has neglected the effect of varying dielectric permittivity on their dynamic oscillations and stability. This paper studies the thin-walled dielectric balloon in which the stretch-dependent dielectric permittivity is considered. We obtain the dynamic equation of motion by Hamilton's principle. Based on the principle of no energy dissipation in conservative systems, we establish energy conservation at the maximum stretching position and at the initial moment, then we investigate the stability in the dynamic case. It is found that a stretch-related dielectric permittivity can increase the critical electric field of the balloon and can also change the mode of electric field instability and modulate the critical stretch value. In the dynamic case, the stretch-dependent permittivity increases the critical electric field by 4 % when the balloon is only subjected to electric force; moreover, it increases the critical stretch value by 316.68 % by changing the unstable mode from pull-in instability to snap-through instability. It is hoped that this work will provide new thinking in designing functional devices by using the dynamical response and stability of dielectric elastomers. [ABSTRACT FROM AUTHOR]

This work employs density functional theory calculations to investigate the structural, hydrogen storage, mechanical, electronic, optical, and bonding characteristics of perovskite hydrides KNaX 2 H 6 (X = Mg, Ca) for potential hydrogen storage applications. Negative formation energies, positive phonon dispersions, and appropriate tolerance factor values confirm the thermodynamic, dynamic, and cubic structural stability of these compounds. KNaMg 2 H 6 exhibits a promising gravimetric hydrogen storage capacity of 5.19%, while KNaCa 2 H 6 shows 4.09%. Both compounds display semiconducting behavior with indirect energy band gaps of 3.31 eV and 3.17 eV, respectively. Key mechanical properties, including bulk modulus, shear modulus, and Poisson's ratio, were evaluated using computed elastic constants. The desorption temperature for KNaMg 2 H 6 , determined to be 470.4 K, renders it suitable for practical applications. Partial Bader charge analysis reveals both ionic and slightly covalent bonding interactions. Optical analysis demonstrates strong ultraviolet absorption capabilities with a redshift in the absorption spectrum. The computed properties indicate these materials hold promise for hydrogen storage applications. • DFT study of KNaX 2 H 6 (Y Mg, Ca) perovskites for H 2 storage applications. • KNaX 2 H 6 (Y Mg, Ca) hydrides are mechanically and thermodynamically stable. • KNaX 2 H 6 (Y Mg, Ca) hydrides are semiconductors in nature. • The gravimetric ratios are found 5.19% for KNaMg 2 H 6 and 4.09% for KNaCa 2 H 6. [ABSTRACT FROM AUTHOR]

The Mercury Sulphohalides have attracted significant attention in the fields of solar cells and thermoelectric applications. This study delves into the fundamental characteristics, including structural, elasticity, electronic behavior, phonon stability, optical properties, and transport features of AgHgSZ (Z = Br, I) through computational simulations based on Density Functional Theory (DFT) using WIEN2k software. Meticulous calculations of the phonon band structure ensure dynamic stability. The semiconductor nature with indirect band gaps (1.833 eV and 1.832 eV) for Mercury Sulphohalides (Br, I), as revealed by their band structures, suggests diverse photovoltaic and transport applications. Mechanical assessments show stable ductility for AgHgSBr and brittleness for AgHgSI, along with anisotropy and resistance to scratching. Optical properties exhibit anisotropy and significant UV absorption. Analysis of effective masses, exciton binding energy, and exciton Bohr radius suggests low exciton binding energy and classification under Mott-Wannier excitons. Positive thermopower results indicate holes as the predominant charge carriers in AgHgSBr and AgHgSI materials. Moreover, essential thermoelectric factors are examined, revealing the compounds' potential for thermoelectric applications. Notably, the figure of merit (ZT) at 300 K for AgHgSBr and AgHgSI are calculated to be 0.41 and 0.13, respectively. While these values are low at 300 K, they indicate promising potential for thermoelectric applications at higher temperatures. In summary, this investigation provides valuable understanding into the photovoltaic and thermoelectric properties of AgHgSZ (Z = Br, I) materials, potentially paving the way for further exploration in this domain. [ABSTRACT FROM AUTHOR]

This paper presents a modular approach to motion planning with provable stability guarantees for robots that move through changing environments via periodic locomotion behaviors. We focus on dynamic walkers as a paradigm for such systems, although the tools developed in this paper can be used to support general compositional approaches to robot motion planning with dynamic movement primitives (DMPs). By formulating the planning process as a switching system with multiple equilibria (SSME), we prove that the system's evolution remains within explicitly characterized trapping regions in the state space under suitable constraints on the frequency of switching among the DMPs. These conditions encapsulate the low-level stability limitations in a form that can be easily communicated to the planner. Furthermore, we show how the available primitives can be safely composed online in a receding horizon manner to enable the robot to react to moving obstacles. The proposed framework can be applied in a wide class of 3D bipedal walking models, and offers a modular approach for integrating readily available low-level locomotion control and high-level planning methods. [ABSTRACT FROM AUTHOR]

By increasing the number of electric vehicles (EVs) to achieve a less carbon environment, not only they consume power from the grid to be charged, but also do they deliver power to the grid, and this can play a significant role in load frequency control. However, EVs take part in frequency regulation based on their state of charge (SoC) which will cause uncertainties. In order to manage these uncertainties, EV aggregator (EVA) concept has been introduced. The EV owner participates in the demand response program provided by the EVA arbitrarily considering her/his requirements. Accordingly, EVA calculates the up and down power reserve for the power system operator. Following any frequency deviation, EVA sends the proper commands to each EV to consume or to inject power to the system. There are also communication delays between different parts, uncertainties, and non‐linearities that existed in the power system. To overcome these issues, this study proposes a new robust load frequency controller based on feedback theory and artificial neural network which is designed through the non‐linear multi‐machine power system. Simulation results on IEEE 39‐bus power system show that the proposed controller regulates frequency more desirably in comparison with other methods. [ABSTRACT FROM AUTHOR]

The structural stability of clamped-free beam-columns resting on a two-parameter foundation under a nonconservative force is investigated. The higher-order beam theory is developed by considering the warping of the cross-section, rotary inertia, and axial force's direction. The characteristic equation of dynamic stability of rectangular/circular cantilevers on a Winkler-Pasternak foundation is obtained for a generalized follower force. Critical loads for divergence instability and flutter instability are evaluated. The influences of foundation stiffness, cross-sectional warping shape, the tangency coefficient on the critical loads are analyzed. The load-frequency interaction-curves are given for different directions of the follower force. The normal/shear stiffness of foundation on divergence and flutter loads has different effects. The normal stiffness increases the first divergence load but decreases the flutter load, reducing to the Herrmann–Smith paradox for Euler columns. The rise of shear stiffness enlarges the first divergence load and lowers the flutter loads. The effects are more sensitive for short beam-columns. Different warping shapes slightly affect the critical loads and the natural frequencies. The exponential warping shape gives the smallest critical divergence loads and the fundamental frequencies. The results of Haringx hypothesis are larger than those of Engesser hypothesis. For shorter columns, the classical results are overestimated and the higher-order beam theory is necessary. [ABSTRACT FROM AUTHOR]

The traction motors installed on the bogie frame of high-speed trains are of adverse effect on the bogie hunting stability. Utilising the elastic-suspended motors as dynamic vibration absorbers can increase the hunting critical speed. However, the vibration and dynamic stress of the motor system will be aggravated compared to the rigid motor suspension. In this work, the hunting stability and dynamic stress of a high-speed bogie with elastic-suspended motors are studied. Firstly, the DVA mechanism of hunting stability for a bogie with elastic-suspended motors is conducted by the eigenvalue method. Increasing the critical speed by the elastic motor suspension will sacrifice the motor vibrations and stresses. Secondly, the rigid-flexible coupled dynamic model of the vehicle and motor system is developed to give insight into the consequent effects on dynamic stress. Finally, some countermeasures, e.g. wheel-rail conicity control and motor suspension optimisation, are proposed to suppress the dynamic stress of the motor hanger system. One effective manner to suppress the dynamic stress of the motor hanger system is to improve the hunting stability by limiting the wheel-rail conicity. Another one is to lower the lateral stiffness of the motor suspension and increase the damping ratio of the motor damper. [ABSTRACT FROM AUTHOR]

Lower limb injuries in dancers are a very common complication preventing them from maximizing their performance or even causing one to end their dance career. The aim of this study was to investigate the dynamic stability using the Y-balance test (YBT) in professional folk dancers in comparison with the non-dancers. The study involved 30 folk dancers from the Urpin Folk Group and a control sample of 30 individuals from the general. Analysis of the results showed no statistically significant difference between the folklorist group and the control group in the anterior direction. However, the differences between groups were statistically significant for the posteromedial direction with the medium effect size for both legs and for the posterolateral direction with the strong effect size for both legs. The differences in the composite score for the right leg were not statistically significant with the small effect size, yet the difference in the left leg in the composite score was statistically significant with the strong effect. The results of the study indicate that folk dancers present poorer dynamic balance compared to the general population. [ABSTRACT FROM AUTHOR]

Enhancing the vibration behaviour of rotating systems while meeting conflicting design needs is a difficult task, which is often treated as an inverse issue and formulated as a nonlinear optimization problem with constraints. To tackle this intricate challenge, a novel hybrid algorithm (HDE-Jaya) has been developed, combining the differential evolution (DE) and Jaya methods. The Jaya model is integrated into DE as a mutation operator to boost exploration and exploitation. In addition, the crossover probability is generated randomly at each iteration to preserve diversity. This makes HDE-Jaya a parameter-free algorithm. The performance of HDE-Jaya was validated by optimizing six common mechanical engineering design problems and further evaluated on an automotive turbocharger design, aiming to reduce vibrations, minimize binding stress and improve dynamic stability. The results indicate that HDE-Jaya is superior to other algorithms, including DE and the Jaya algorithm, in terms of solution accuracy and computational efficiency. [ABSTRACT FROM AUTHOR]

This paper presents a mathematical study applied to Hepatitis B disease utilizing fractional calculus and numerical methods. We begin by discussing mathematical fundamentals, focusing on fractional calculus concepts and relevant numerical aspects for disease modeling. We then formulate the problem, describing a nonlinear fractional differential system that models hepatitis B virus (HBV) infection and its response to drug therapy. A detailed theoretical analysis explores system properties and biological implications. We provide a qualitative analysis of the model, discussing important dynamic behaviors such as stability and parameter sensitivity. Subsequently, numerical analysis is performed to validate the model and estimate unknown parameters from patient data. Our findings include significant insights into biological parameters and their impact on therapeutic response. We conclude that the proposed fractional-order model is effective, offering optimal therapeutic strategies for hepatitis B. [ABSTRACT FROM AUTHOR]

The association between low back pain and lumbar spine local dynamic stability (LDS) appears to be modulated by if and how someone catastrophizes about pain, suggesting that the cognitive perceptions of pain may influence an individual's ability to control lumbar spine motion. Previous work also demonstrates that directing cognitive resources and attentional focus can influence movement performance. Therefore, we aimed to examine whether distracting attentional focus would influence lumbar spine LDS during repetitive flexion-extension movements. Sixteen participants performed repetitive spine flexion-extension movements under two baseline conditions (pre- and post-), and while attentional focus was distracted by either an external sensory stimulus or a cognitive-motor dual-task, both targeted at the hands. Lumbar spine LDS was examined over 30 continuous movement repetitions using maximum Lyapunov exponents. In comparison to both Baseline and Post-Baseline trials, the perceived mental workload was significantly elevated during the cognitive-motor dual-task trial but not the external sensory stimulus trial. The only statistically significant effect on LDS occurred in the Post-Baseline trial, where LDS was higher than in the cognitive-motor dual-task. In combination with previous work, these findings suggest that distracting attentional focus during repetitive lumbar spine flexion-extension movements does not have a negative influence on lumbar spine LDS. [ABSTRACT FROM AUTHOR]

Visual simultaneous localization and mapping (SLAM) in dynamic environments has received significant attention in recent years, and accurate segmentation of real dynamic objects is the key to enhancing the accuracy of pose estimation in such environments. In this study, we propose a visual SLAM approach based on ORB-SLAM3, namely dynamic multiple object tracking SLAM (DMOT-SLAM), which can accurately estimate the camera's pose in dynamic environments while tracking the trajectories of moving objects. We introduce a spatial point correlation constraint and combine it with instance segmentation and epipolar constraint to identify dynamic objects. We integrate the proposed motion check method into DeepSort, an object tracking algorithm, to facilitate inter-frame tracking of dynamic objects. This integration not only enhances the stability of dynamic features detection but also enables the estimation of global motion trajectories for dynamic objects and the construction of object-level semi-dense semantic maps. We evaluate our approach on the public TUM, Bonn, and KITTI dataset, and the results show that our approach has a significant improvement over ORB-SLAM3 in dynamic scenes and performs better compared to other state-of-the-art SLAM approaches. Moreover, experiments in real-world scenarios further substantiate the effectiveness of our approach. [ABSTRACT FROM AUTHOR]

This paper investigates the issue of observer-based dual-dynamic event-triggered scheme into networked control systems, focusing on its application to motion robots. Firstly, it establishes a mathematical model of the motion robot system based on Newtonian mechanics. Secondly, it introduces a dynamic event-triggering mechanism coupled with observer design to minimize data transmission and enhance communication efficiency. Thirdly, it implements a second dynamic event-triggering protocol for controller design, ensuring a positive lower bound for triggering event intervals, thus avoiding Zeno behavior. Fourthly, it constructs a Lyapunov function with internal dynamic variables for stability analysis using linear matrix inequalities. Finally, simulation studies validate the method's efficacy for motion robot systems. [ABSTRACT FROM AUTHOR]

The ability of living organisms to persist, grow, evolve and invade environments seemingly challenges physical laws. Emerging Autonomous Systems representing autocatalytic cycles constituted of energized components in a state of Dynamic Kinetic Stability feature some of these properties. These simple theoretical models can grow, can be transferred but need an initiation to emerge and can collapse. Moreover, they can undergo kinetic selection in a way consistent with Darwinian behaviour, though they lack the ability to undergo change. The mere existence of these systems and their open‐ended growth potential are proposed to constitute a transmissible factor of a non‐coded kind. The onset and selection of epigenetic factors may therefore have preceded that of genetic polymers. Here is addressed the question of how these systems may arise from the diversity exhibited by abiotic organic matter, sometimes associated with intractable mixtures, which may actually be useful in providing initiators. The Darwinian description of evolution may therefore be merged without critical discontinuity within an origin scenario. Accordingly, such a theory would rests solely on physicochemical laws beginning with the potential of emerging autonomous systems to compete and invade the space dimension, and to further develop along other available dimensions including variability and, possibly, cognition. [ABSTRACT FROM AUTHOR]

Eutectogels have attracted increasing attention from researchers due to their broad application potential, good environmental stability, biocompatibility, and low cost. Currently reported eutectogels generally show large residue strain and hysteresis, which will cause output signal inconsistency between the loading and unloading processes and is not conducive to accurate strain monitoring. Besides, the low adhesiveness of available eutectogels brings about difficulties in the installation of the sensors and dynamic interfacial stability between the sensors and human skin. Herein, a dual ion regulation strategy is proposed to obtain eutectogels with high resilience, high adhesiveness, ultralow residue strain, wide temperature adaptability (−20–60 °C) and good environmental stability. Strain sensors based on gradient eutectogels exhibit high sensitivity, a wide linear response range, and good cycling stability. The response curve shows negligible electrical hysteresis, providing consistent output signals at the fixed strain regardless of stretch or release. Accurate micrometry with a step as minute as 50 µm is realized. Moreover, the sensors demonstrate higher signal intensity and stability in human physiological signals and motion detection due to the strong interfacial bonding. [ABSTRACT FROM AUTHOR]

Some of spiro[chromane-3',2''-thiopyran]-4'-ones were oxidized via m-chloroperbenzoic acid and/or hydrogen peroxide to afford the corresponding nine spiro[chromane-3',2''-thiopyran]-4'-one 1''-oxides and three spiro[chromane-3',2''-thiopyran]-4'-one 1'',1''-dioxides, which were confirmed by spectral data (IR, 1H NMR, 13C NMR, MS-ESI, and MS-EI). Whereas, the yield of oxidation using hydrogen peroxide is higher than that of oxidation using m-chloroperbenzoic acid. Moreover, Gram-negative bacteria (Escherichia coli ATCC 25922), and Gram-positive bacteria (Staphylococcus aureus ATCC 6538) were adopted to test the antimicrobial activity of 12 newly synthesized compounds (7a, 8a-c, 9a, 10a-c, 11a, 12a-c). The three sulfoxide derivatives 8b, 10b, and 10c showed antimicrobial activity. Also, antioxidant activity was evaluated for the newly synthesized compounds and shows that, all newly synthesized compounds (7a, 8a-c, 9a, 10a-c, 11a, 12a-c) have antioxidant activity. Molecular dynamic and system stability, Binding interaction mechanism based on binding free energy calculation, Identification of the critical residues responsible for ligands binding, Ligand–residue interaction network profiles, and In silico ADMET properties prediction were studied for the new compounds. The results of molecular dynamic studies were consistent with the in vitro antibacterial and antioxidant activity. [ABSTRACT FROM AUTHOR]

We develop a theory of the critical point of the ferromagnetic Ising model, whose basic objects are the ergodic (pure) states of the infinite system. It proves the existence of anomalous critical fluctuations, for dimension ν = 2 and, under a standard assumption, for ν = 3 , for the model with nearest-neighbor interaction, in a way which is consistent with the probabilistic approach of Cassandro, Jona-Lasinio, and several others, reviewed in Jona-Lasinio's article in Phys. Rep. 352,439 (2001). We propose to single out the state at the critical temperature T c , among the ergodic thermal states associated to temperatures 0 ≤ T ≤ T c , by a condition of non-summable clustering of the connected two-point function. The analogous condition on the connected (2r)- point functions, for r ≥ 2 , together with a scaling hypothesis, natural within our framework, proves that the (macroscopic) fluctuation state is quasi-free, after a proper rescaling, also at the critical temperature, in agreement with a theorem by Cassandro and Jona-Lasinio, whose proof is, however, shown to be incomplete. Other subjects treated include topics relating to universality, including spontaneous breaking of continuous symmetries and violations of universality in problems of energetic and dynamic stability. [ABSTRACT FROM AUTHOR]

From time to time, a series of unpredictable and conflicting contingencies can lead to angular instability of the power system and even blackouts if not adequately handled by an out-of-step (OOS) protection system. The key contribution of this research work, to the theory of out-of-step protection, is the identification and isolation after a given disruption of many unstable swings. This paper presents a proposed method to avoid false operation for distance function by out-of-step blocking to improve the system stability by using optimally placed PMUs for the fast detection of system analogue quantities. The studies were performed on a modified Eskom transmission network in the Western Cape with 765 kV and 400 kV voltage levels. The aim is to investigate the IEC 61850-90-5 standard for predictive dynamic stability maintaining systems using PMUs for out-of-step conditions of synchronous generators. The power system modelling and simulation are performed in the RSCAD-FX for the proposed multi-area power system network. An experimental lab-scale implementation is built to test the proposed out-of-step algorithm in a real-time digital simulator. Software-based PMU is incorporated to test and validate the IEC 61850-90-5 standard sampled values. Simulation and experimental results are presented. [ABSTRACT FROM AUTHOR]

Recent years have seen high penetration of renewable energies, which have significantly reduced the inertia of bulk power systems. As a result, the frequency behaviour of power systems is becoming more complex. To resolve this technical challenge, there is a particularly strong interest in developing analytical solutions for frequency dynamics studies. This study first describes a second‐order frequency dynamics model for power systems with renewable energies. A non‐linear perturbation approach is suggested to drive the analytical solution of the model. It is shown that, under many circumstances, frequency dynamics can be effectively approximated using a linear model. Subsequently, the article describes a fourth‐order linear frequency dynamics model that takes into account governor‐turbines. A polynomial eigenvalue method is proposed to identify the dominant and non‐dominant modes of the solution of the four‐order model. It is demonstrated that the dominant mode has a decisive impact on frequency behaviour, while the non‐dominant modes influence the relative frequency oscillations only. Finally, the study derives the analytical expressions of the standard frequency performance metrics and examines the impact of damping and inertia parameters. The introduced results are verified using two test systems, demonstrating the accuracy and effectiveness of the suggested method. [ABSTRACT FROM AUTHOR]

The droop control strategy is popularly employed in DC microgrids. However, its virtual resistance will cause voltage deviation and reduce transient response. The DOB‐based method is proven to improve transient response in literature. However, it is analyzed in this study that this method will negatively influence the current sharing when employed in droop control. A weakened disturbance observation (WDOB) is proposed in this work to improve the drawbacks. To employ the proposed method, the equivalent models of the droop controller and the physical system are separately established, and several transformations are conducted. An auxiliary compensation is added and the current loop is considered as a whole to be transmitted into the control plant, making the traditional DOB method successfully adopted. It is obvious that the dynamic performance is improved, but it disabled virtual resistance in the steady‐state. And the current sharing cannot be achieved in a multi‐converter parallel system. The reason for this problem is analyzed from the control process and transfer function, and the WDOB solution is finally proposed. Through the proposed method, both aims of improving dynamic response and current sharing can be achieved, and the steady voltage deviation is much less than that of the traditional droop controller. [ABSTRACT FROM AUTHOR]

The influence of internal and external nonlinear damping forms on the dynamics of a generalized Beck's column, namely a visco-elastic cantilever beam, subjected to conservative and non-conservative loads at its free end, is investigated. A variational principle provides the equations of motion of the system, which are properly recast into an integro-differential form. The linear stability analysis of the system is then carried out and bifurcation points are detected in the space of parameters associated with the conservative and non-conservative loads. Starting from Hopf's bifurcation points, a post-critical analysis, based on the Method of Multiple Scales is directly performed on the continuous system, avoiding any a-priori discretization. This method provides the bifurcation equations whose analysis reveals the double nature of nonlinear damping, which can be beneficial or detrimental in terms of stable or unstable bifurcated equilibria. It is found that both the internal and external forms of nonlinear damping can turn a supercritical instability of the system into a subcritical one, thus revealing another destabilizing effect of damping, beyond the very well-known one occurring in the linear field. Numerical simulations, grounded on a Galerkin discretization of the original system, confirm the analytical findings. [ABSTRACT FROM AUTHOR]

Volume parameters such as the volume of voids (VV), voids filled with asphalt (VFA), and voids in mineral aggregates (VMA) all have significant impact on asphalt mixtures. In this study, the vertical vibration compaction method (VVCM) was employed to produce a large-particle-size asphalt mixture (LSAM-50). The correlations between the mechanical strengths of VVCM specimens, static compression test (PCT) specimens, and in situ core samples were verified. Additionally, the influence of volumetric parameters on the mechanical properties of VVCM specimens was assessed. Based on the principle of optimal mechanical properties, volume parameter design standards for the LSAM-50 asphalt mixture were proposed. Results indicated that the mechanical properties correlation between VVCM specimens and in situ core samples was substantial, reaching over 90%. With increasing VV and VFA, the compressive strength, splitting strength, and dynamic stability of the LSAM-50 asphalt mixture initially increased and then decreased. The design standards for VV were proposed to be between 3.5% and 4.8%, and for VFA between 49.7% and 52.9%. There was no clear correlation between VMA and the mechanical properties of the mixture; hence, based on the standards, the minimum design value for VMA was set at 7.5%. [ABSTRACT FROM AUTHOR]

Polymer nanocomposites with tuning functions are exciting candidates for various applications, and most current research has focused on static mechanical reinforcement. Actually, under service conditions of complex dynamic interference, stable dynamic mechanical properties with high energy dissipation become more critical. However, nanocomposites often exhibit a trade-off between static and dynamic mechanics, because of their contradictory underlying physics between chain crosslinking and chain relaxation. Here, we report a general strategy for constructing ultra-stable dynamic mechanical complex fluid nanocomposites with high energy dissipation by infusing complex fluids into the nanoconfined space. The key is to tailor full-scale polymer dynamics across an exceptionally broad timescale by single-chain confinement. These materials exhibit stable storage modulus (100 ~ 102 MPa) with high energy dissipation (loss factor > 0.4) over a broad frequency range (10−1 ~ 107 Hz)/temperature range (−35 ~ 85°C). In the loss factor > 0.4 region, their dynamic mechanical stability (rate of modulus change versus temperature (k)) is 10 times higher than that of conventional polymer nanocomposites. Under service conditions of complex dynamic interference, stable dynamic mechanical properties with high energy dissipation becomes more critical but nanocomposites often exhibit a trade-off between static and dynamic mechanics. Here, the authors report a general strategy for constructing ultra-stable dynamic mechanical complex fluid nanocomposites with high energy dissipation by infusing complex fluids into the nanoconfined space. [ABSTRACT FROM AUTHOR]

This paper introduces a novel numerical method for investigating the dynamic stability of a flutter panel exposed to a supersonic gas flow and a fluctuating axial excitation force. Initially, the system equation of motion was derived using Lagrange’s equation, where the first two modes are coupled Mathieu–Hill equations with damping, constituting a system of linear second-order differential equations with periodically variable coefficients. Subsequently, a new numerical method was proposed to analyze the dynamic stability of coupled Mathieu–Hill equations with damping. This method involves breaking down an arbitrary parametric load into discrete segments to approximate the variable excitation function using a step function. The system responses of each segment are then accumulated in matrix form. The proposed numerical method proves particularly effective for dynamic systems whose parameters cannot be treated as small. In practical application, the method allows the construction of instability regions corresponding to natural frequencies, subharmonics, and combination frequencies. Dynamic stability diagrams were generated based on dynamic pressure ratio, air/panel density ratio, Mach number, panel thickness—length ratio, and excitation frequency. The results demonstrated general agreement with those obtained through Hsu’s perturbation method, however, our numerical results have proven more accurate. The paper concludes by offering suggestions for suppressing panel flutter through appropriate parameter combinations. [ABSTRACT FROM AUTHOR]

Robots execute diverse load operations, including carrying, lifting, tilting, and moving objects, involving load changes or transfers. This dynamic process can result in the shift of interactive operations from stability to instability. In this paper, we respond to these dynamic changes by utilizing tactile images captured from tactile sensors during interactions, conducting a study on the dynamic stability and instability in operations, and propose a real-time dynamic state sensing network by integrating convolutional neural networks (CNNs) for spatial feature extraction and long short-term memory (LSTM) networks to capture temporal information. We collect a dataset capturing the entire transition from stable to unstable states during interaction. Employing a sliding window, we sample consecutive frames from the collected dataset and feed them into the network for the state change predictions of robots. The network achieves both real-time temporal sequence prediction at 31.84 ms per inference step and an average classification accuracy of 98.90%. Our experiments demonstrate the network's robustness, maintaining high accuracy even with previously unseen objects. [ABSTRACT FROM AUTHOR]

This study aimed to assess the responsiveness to the rehabilitation of three trunk acceleration-derived gait indexes, namely the harmonic ratio (HR), the short-term longest Lyapunov's exponent (sLLE), and the step-to-step coefficient of variation (CV), in a sample of subjects with primary degenerative cerebellar ataxia (swCA), and investigate the correlations between their improvements (∆), clinical characteristics, and spatio-temporal and kinematic gait features. The trunk acceleration patterns in the antero-posterior (AP), medio-lateral (ML), and vertical (V) directions during gait of 21 swCA were recorded using a magneto-inertial measurement unit placed at the lower back before (T0) and after (T1) a period of inpatient rehabilitation. For comparison, a sample of 21 age- and gait speed-matched healthy subjects (HSmatched) was also included. At T1, sLLE in the AP (sLLEAP) and ML (sLLEML) directions significantly improved with moderate to large effect sizes, as well as SARA scores, stride length, and pelvic rotation. sLLEML and pelvic rotation also approached the HSmatched values at T1, suggesting a normalization of the parameter. HRs and CV did not significantly modify after rehabilitation. ∆sLLEML correlated with ∆ of the gait subscore of the SARA scale (SARAGAIT) and ∆stride length and ∆sLLEAP correlated with ∆pelvic rotation and ∆SARAGAIT. The minimal clinically important differences for sLLEML and sLLEAP were ≥ 36.16% and ≥ 28.19%, respectively, as the minimal score reflects a clinical improvement in SARA scores. When using inertial measurement units, sLLEAP and sLLEML can be considered responsive outcome measures for assessing the effectiveness of rehabilitation on trunk stability during walking in swCA. [ABSTRACT FROM AUTHOR]

We study the propagation rules of acoustic bright solitons in bubble-containing media, as well as the strong anti-interference ability of acoustic solitons; and the effects of nonlinearity, dispersion, and dissipation on the dynamic properties of acoustic solitons are also analyzed. Based on the bubble–liquid mixture model, a lossy nonlinear Schrödinger equation is obtained. The analytical expression of the enveloped bright-acoustic solitons in the bubbly liquids is derived, which can accurately capture the propagation law of the acoustic bright solitons in the physical system, even if there is viscous loss in the medium. The dissipation-induced dynamics of acoustic solitons is studied through analytical and numerical methods, and the balancing effects of nonlinearity and dispersion in the propagation of bright solitons are analyzed. Furthermore, the particle nature and dynamic stability of bright-acoustic solitons in bubble-containing media are emphasized through fully elastic collisions between solitons moving in the same and opposite directions. This process obeys the energy and momentum conservation laws. After the collision, solitons can maintain their original amplitude, speed, and shape and continue to propagate undisturbed. [ABSTRACT FROM AUTHOR]

This paper conducts an in-depth study on the dynamic stability and complex vibration behavior of a 12-pole active magnetic bearing (AMB) system considering gravitational effects under a PD controller. Firstly, based on electromagnetic theory and Newton's second law, a two-degree-of-freedom control equation of the system, including PD control terms and gravitational effects, is constructed. This equation involves not only parametric excitation, quadratic nonlinearity, and cubic nonlinearity but also a more pronounced coupling effect between the magnetic poles due to the presence of gravity. Secondly, using the multi-scale method, a four-dimensional averaged equation of the system in Cartesian and polar coordinates is derived. Finally, through numerical analysis, the system's amplitude–frequency response, motion trajectory, the relationship between energy and amplitude, and global dynamic behaviors such as bifurcation and chaos are discussed in detail. The results show that the PD controller significantly affects the system's spring hardening/softening characteristics, excitation, amplitude, energy, and stability. Specifically, increasing the proportional gain can quickly suppress the rotor's motion, but it also increases the system's instability. Adjusting the differential gain can transition the system from a chaotic state to a stable periodic motion. [ABSTRACT FROM AUTHOR]

As an environmentally friendly material, biochar is increasingly being utilized in the field of heat transfer and thermal conduction. In this study, nano-biochar was prepared from high-pressure homogenization (HPH) using sesame stalks as the raw material. It was incorporated into ethylene glycol (EG) and its dispersion stability, viscosity, and thermal conductivity were investigated. The nano-biochar was stably dispersed in EG for 28 days. When the concentration of the nano-biochar added to EG was less than 1%, the impact on viscosity was negligible. The addition of 5 wt.% nano-biochar to EG improved the thermal conductivity by 6.72%, which could be attributed to the graphitized structure and Brownian motion of the nano-biochar. Overall, nano-biochar has the potential to be applied in automotive thermal management. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to carry out parameter design and dynamic stability verification experiment of controllable damping ferrofluid bearing. A new type of ferrofluid bearings is designed, and its internal magnetic fields are simulated by the finite element analysis software ANSYS. In this paper, the coefficient of magnetic leakage is taken as the optimization object, and the optimal parameters of ferrofluid bearings are updated. At the same time, the working principle of the ferrofluid bearings test platform is introduced, which includes a servomotor with a controller, an eddy displace sensor, an amplifier and a power supply. Finally, the dynamic stability of ferrofluid bearing is verified by experiments. The experimental results show that when the applied current is less than or equal to 0.08 A, the amplitude of the rotor supported by the ferrofluid bearing decreases with the applied current increment. Besides, the dynamic stability of the rotor is also related to the rotational speed. When the applied current is 0.08 A, the amplitude of the rotor supported by the ferrofluid bearing firstly increases and then decreases with the rotational speed increment. It is proved that the ferrofluid bearings have a strong function of the dynamic stability, which can suppress the vibration of the rotor, and have high accuracy of both position and rotation. [ABSTRACT FROM AUTHOR]

The incorporation of converter-based generating sources in utility-scale microgrids causes frequency instability and low-frequency oscillations (LFOs), which is also a reason for degeneration in system stability. Damping frequency control is an essential part of alternating current (AC) microgrid system operation and control. Sudden changes in load, variations in renewable power outputs due to changes in solar insolation or wind speed, and so on factors cause the system frequency to deviate from the nominal value. Therefore, the role of a frequency controller is to maintain the dynamic stability in an AC microgrid by retaining the system frequency at the nominal value. Again, AC microgrids with high renewable power penetration face even more difficulty in maintaining frequency stability because of their poor inertial response. The research presented here proposes a novel approach for grid-connected AC microgrid oscillation damping and frequency control that simultaneously takes into consideration time delay and noise. To improve the frequency response and dampen LFOs by providing the voltage and frequency within the specified range, a coordinated technique-based control approach is adopted. In the developed hybrid control, the frequency controller relies on active power modulation, while the power oscillation damping controller is dependent on reactive power modulation. To improve stability and reduce communication consequences such as noise and signal latency (time delay), the developed power oscillation damping controller and frequency controller are coordinated along with the robust linear quadratic Gaussian controller. The comparative investigation of the effectiveness of the coordinated control technique is employed in the software of MATLAB/Simulink for grid-connected AC microgrid. The outcome of the simulation illustrates the superior effectiveness of the suggested controller over the traditional droop controller for huge power flows under disturbance with various operating conditions, under/overfrequency events, time delay, and noise. This grid encouragement capability for AC microgrids is anticipated to lead to novel possibilities for generating revenue. [ABSTRACT FROM AUTHOR]

Bisphenol A-based phthalonitrile resin was synthesized by nucleophilic substitution reaction from bisphenol A and 4-nitrophthalonitrile, and then the obtained resin was cured with sulfaguanidine as a novel curing agent. The curing characteristics, kinetics, thermal stability and dynamic mechanical property were studied by standard thermal analysis techniques including DSC, TGA, and DMA. The peak temperature of exothermic peak (T p) and apparent activation energy (E a) of sulfaguanidine cured phthalonitrile resin were 263.20°C and 76.6 kJ·mol−1 respectively, much lower than those of traditional aromatic diamine cured resin. Moreover, the resin cured by sulfaguanidine showed excellent thermomechanical properties and thermal stability. The glass transition temperature (T g) was 284.8°C, the initial thermal decomposition temperature (T d,5%) was 439.6°C, and the char yield at 800°C was 62.1% in nitrogen atmosphere. To sum up, organic guanidine cured phthalonitrile resin exhibits excellent curing characteristics (low T p and E a) and high thermal properties, which provides a promising approach to preparing phthalonitrile resin with high comprehensive performance. [ABSTRACT FROM AUTHOR]

Fluorite, as a vital calcium-containing mineral, usually coexists with calcite. When using the traditional collector sodium oleate (NaOL), froth flotation could not separate fluorite and calcite well on account of their similar surface properties. Meanwhile, a large amount of sodium silicate (SS) needs to be added to depress calcite, resulting in difficulties in tailings settlement and wastewater treatment. Therefore, a nontoxic and inexpensive surfactant saponified tricarboxylic acid (TA) was developed as a new collector. The flotation test results showed that TA had a higher selectivity for fluorite than NaOL, leading to the selective separation of both minerals. Zeta potential measurements indicated that TA was negatively charged and was strongly adsorbed on fluorite due to electrostatic interactions at pH 9.0. FTIR, XPS, DFT, and crystal chemistry calculations revealed TA had a stronger chemical interaction with fluorite due to its higher surface Ca activity and density, forming a TA-Ca complex through the bidentate coordination. In contrast, the interaction of TA with calcite could be ignored. In addition, the results of the surface tension and dynamic foam stability tests revealed that TA possessed the excellent foam performance. Therefore, these properties give TA excessive potential for industrial application and environmental protection in fluorite flotation. Density and activity of Ca atoms on fluorite are higher than those on calcite. TA could selectively separate fluorite from calcite without any depressants. TA had a stronger chemical interaction with fluorite to form the Ca – TA complex. TA possesses excellent foam properties and suitable hydrophobicity. [ABSTRACT FROM AUTHOR]

Injuries involving ankle stability and range of motion are among the most frequent in athletes and in the general population. In response, this study aimed to assess the immediate effects of toe separators on dynamic stability and ankle range of motion in healthy young individuals. Among the 68 eligible participants, 50 healthy and active subjects completed all trials. The impact of the intervention was evaluated using the Weight Bearing Lunge Test and Y-Test. The control condition performed the tests without toe separators, while the experimental condition performed the tests with toe separators. All participants performed both conditions with a wash-out period of at least 7 days between trials. Statistical analysis revealed no significant differences in dynamic balance (p > 0.05) and range of motion (p > 0.05) between the two conditions. Additionally, no asymmetries were detected between the lower limbs in both tests (p > 0.05). The results of this pilot study indicate that using toe separators does not have an immediate effect on ankle range of motion and dynamic balance in young, healthy individuals. Future research should consider evaluating intervention programs of longer duration and exploring different populations. [ABSTRACT FROM AUTHOR]

Renewable energy, particularly wind energy, is expected to contribute significantly to the overall power generation. Induction machines are extensively used as generators in wind power generation because of their multiple benefits, such as robustness, reliability, and low cost and maintenance. However, due to the reactive power demand from the system to which they are connected, this type of generator brings new problems related to power quality, generally consisting of voltage regulation and reactive power compensation. These problems may cause voltage drops and dynamic instability. This study presents a metaheuristic method to attain a microgrid system with an optimal distribution based on its different constraints. The numerical model of an induction generator constructed in MATLAB/Simulink was used, and the simulation results obtained demonstrate the efficacy of the proposed metaheuristic technique. [ABSTRACT FROM AUTHOR]

The influence of imperfections in element length and loading on the dynamic buckling of plane trusses is investigated in the present study. Finite element formulation and the Euler formula are employed to tackle the problem of large displacements. Equivalently, the Newmark integration method and the Newton-Raphson iteration algorithm are deployed to solve the nonlinear dynamic equilibrium equations. The dynamic applied load considered in this study is a step-imperfect load with an imperfection in the element length. The relationship between the load and maximum displacement is determined, and the simultaneous influence of the imperfect parameters on the dynamic limit load is discussed. The imperfect element length and loading significantly affect the dynamic limit load, demonstrating the need to consider both imperfections when studying the dynamic buckling of truss systems. [ABSTRACT FROM AUTHOR]

Piston–cylinder pairs are very common in industrial mechanisms. While a piston is primarily designed for axial reciprocating motion, the occurrence of secondary motions—lateral and rotational—due to the small clearance between the piston and the cylinder may lead to frictional contact, energy loss, wear and an increase in unwanted leakage. This study focuses on mitigating the secondary motion of a ringless piston. The influence of a Rayleigh step bearing and partial surface texturing with numerous micro-dimples on the dynamic stability of the secondary motion is studied. A linear model was used to obtain the trajectory of the secondary motion and Floquet theory was applied to analyze the stability and draw stability maps. The influence of various texturing and step parameters, including the dimple area density and aspect ratio for partial texturing, as well as the length and depth of treatment for both partial texturing and step profiles, on the stability of the secondary motion was examined. The normalization method is presented, enabling the expansion of the results for various operating conditions and geometries. Conclusions and guidelines regarding the optimal parameters, in terms of a wider stability range and higher decay rate, are formulated. [ABSTRACT FROM AUTHOR]

With the increasing development of high-speed, large-scale and light-weight ships, the demand for high-tensile steel in ship structures is continuously rising. This has promoted a decrease in plate thickness, which in turn contributes to the critical issue of structural stability. As ships navigate in waves, they are exposed to dynamic loads, making it crucial to investigate the dynamic stability behaviour of ship structures. In this research, the dynamic stability of plates was investigated theoretically, and the influences of boundary conditions and damping were discussed. Then, a numerical simulation system using MITC4 shell elements was developed to investigate the dynamic stability of stiffened plates. An experiment was conducted to validate the accuracy of the simulation system. Finally, the influences of various factors on the dynamic stability of stiffened plates were discussed in detail. This research has significant meaning for the safety and reliability design of ship structures. [ABSTRACT FROM AUTHOR]

Variable air volume air-conditioning system (VAV system) has multiple control loops that interfered with each other, which has serious impacts on its actual operation effect. To solve this problem, the index of global hydraulic stability, which takes the physical quantity of the pipe network pressure and the air flow rate as reference, is proposed based on Graph theory, and a pipe network model for the hydraulic calculation is built. Then, the simulation study based on the actual operation data is carried out in MATLAB. The distribution of the pressure and the air flow in the pipe network is obtained, and the action interferences among adjacent terminal boxes are analyzed based on global hydraulic stability under damper position regulation strategy (DP strategy) and fan frequency regulation strategy (FF strategy). Results indicate that the FF strategy can decrease the total change distance of the damper position compared with the DP strategy, and then the fluctuation of the pressure and the air flow can be reduced. The contribution of this study is to provide an evaluation index of global hydraulic stability, which can also be used in other air-conditioning systems with multiple terminals and multiple control loops. [ABSTRACT FROM AUTHOR]

This paper presents the dynamic voltage stability index based on the voltage oscillation loop for power systems integrated with multiple permanent magnet synchronous generators (PMSGs) to assess the dynamic interaction on voltage stability. First, the model of power systems integrated with multi-PMSGs using a Q--V sensitivity matrix as feedback to connect all PMSGs is established. The transfer function model between voltage and reactive power is derived, and the voltage oscillation loop can be derived, which exists in each PMSG. Next, the dynamic voltage stability index is theoretically derived and given, the impact of dynamic interaction among multi-PMSGs on voltage stability can be quantified, and the source of voltage oscillation can be identified and determined. Then, the voltage stability is recovered by shedding the trouble-making PMSG. The parameters of PMSGs could be tuned with the guidance of the dynamic voltage stability index to reduce the risk of voltage oscillation. Finally, the example of a test system with PMSGs is used to validate the correctness of the dynamic stability index. [ABSTRACT FROM AUTHOR]

The increasing threat of cyber-attacks on modern power systems highlights the need for a comprehensive examination through simulations. This study conducts an in-depth simulation of cyber-attacks on critical smart grid components, including smart meters, substation automation, and battery management systems, to expose and analyze potential disruptions to power system operations. We identify vulnerabilities that can lead to severe grid instabilities, such as voltage variations, system collapses, and inverter failures. Our analysis underscores the complex interactions between cyber threats and grid components, revealing how disruptions extend beyond mere load interruptions to affect the core infrastructure. We advocate for integrating established cybersecurity frameworks like NIST, ISO/IEC 27001, and IEC 62443, essential in fortifying grid stability against these dynamic threats. Our findings highlight the urgent need for continuous adaptation and enforcement of these frameworks to enhance resilience and ensure the reliability of modern power grids against cyber-attacks. [ABSTRACT FROM AUTHOR]

With the increasingly serious problems of international energy shortage and environmental degradation, the adoption of hybrid energy forms represents an effective solution to these challenges and has been widely implemented in the propulsion systems of aircraft, vehicles, and ships. For the hybrid propulsion system with parallel power configuration, a comprehensive investigation has been conducted to understand the system's dynamic characteristics and the evolution laws associated with power parameters. By appropriately simplifying of the actual propulsion system, a nonlinear dynamic model with multi-factor and multi-degree-of-freedom (multi-DOF) coupling is established. The dynamic equations are solved by numerical method, and the motion state of the system under various rotating speeds is revealed through global and local characteristic analyses. The evolution laws of the dynamic characteristics are studies with respect to different combinations of key power parameters, including (λω, λf) and (fo, λf), and the impact of these parameters on the system stability is discussed. Finally, an experimental platform with a parallel drive system is established to quantitatively assess the effects of rotating speed and torque ratio on frequency response, dynamic characteristics, and power efficiency. The results indicate that low rotating speed, heavy load, and large torque ratio have positive implications for the stability of the propulsion system. However, an excessively low torque ratio can significantly compromise power efficiency. It is anticipated that this research will serve as a valuable reference for the design of dynamic stability and optimization of the power configuration in hybrid propulsion systems. [ABSTRACT FROM AUTHOR]

This paper focuses on the analysis and control strategy of a four-switch boost-buck AC/DC converter utilized in power factor correction applications with a wide output voltage range. Given the increasing importance of electric vehicles and the need for high reliability, this study addresses the internal dynamic stability problem that can arise in the converter system. The analysis begins with a thorough examination of the system's min-phase characteristic. Despite this, internal dynamic stability issues persist, requiring a solution to ensure a higher power factor and reliability. To address this challenge, this paper proposes the utilization of a damping RC circuit instead of reducing the loop gain bandwidth. To demonstrate the internal dynamic behavior of the converter, small-signal modeling is employed. This modeling highlights the importance of mitigating internal dynamic instability to achieve the desired power factor and reliability. This study emphasizes the significance of proper analysis and control strategies for boost-buck AC/DC converters in power factor correction applications. By addressing internal dynamic stability using a damping RC circuit, the converter can achieve a higher power factor and enhanced reliability, ultimately contributing to the development of more efficient and dependable EV systems. Finally, the feasibility of the proposed analysis and control strategy is confirmed through comprehensive simulations. The simulation results validate the effectiveness of using a damping RC circuit to address the internal dynamic stability problem, leading to an improved power factor and enhanced reliability. [ABSTRACT FROM AUTHOR]

Borophene with rich polymorphs has largely enriched the family of two-dimensional materials and attracted great research interest. Recently, the evolution of bilayer borophene (BLB) structures has aroused curiosity about the exploration of more members of BLB and their stability mechanism. Herein, we predicted a number of stable BLBs built by borophene monolayers using density functional theory calculations. Interestingly, four BLB polymorphs, such as α5-BLB, β8-BLB, α4-BLB, and β9-BLB, are identified as semiconductors with band gaps of 0.81, 0.34, 0.04, and 0.02 eV, respectively. In addition, four other types of BLBs, i.e., α3-BLB, β1-BLB, β6-BLB, and β12-BLB, are found to be stable metals. It is revealed that the interlayer B–B pillars play a crucial role in balancing the distribution of surplus electronic density in BLBs and are responsible for their super stabilities than those of borophene monolayers. Besides, the strong interlayer covalent interaction plays an important role in the semiconducting properties of these BLBs. Our results are helpful to understand the stability mechanism of BLB structures and expand the family of bilayer borophenes. [ABSTRACT FROM AUTHOR]

One of the most important parts of the structural calculation during their dimensioning is the study of static or even dynamic stability which can be treated in different manners as static buckling, parametric resonance, and dynamic buckling. In this work, we deal with dynamic stability by using the dynamic buckling criteria for functionally graded (FG) material shell structure. This paper aims to determine, in the dynamic case of FG structures composite type, the critical dynamic load using dynamic buckling criteria as phase plan and motion equation criterion. The different mechanical properties are taken as continuous functions through-thickness direction according to the volume fraction of the constituents by a simple power law distribution. The effect of variations of volume fractions and shell geometrical parameters is studied. Convergence tests and comparison studies have been carried out to establish the efficiency of the present model. [ABSTRACT FROM AUTHOR]

The study presented herein was intended to (1) compare the optimum (minimum) dosage requirements of four different sources of polycarboxylate-based high-range water-reducing admixtures (HRWRAs) and viscosity-modifying admixtures (VMAs) in attaining slump flows of 508 mm, 635 mm, and 711 mm, and a visual stability index (VSI) of 0 (highly stable concrete) or 1 (stable concrete), and (2) assess the flowability/viscosity, stability, passing ability, and filling ability of the resulting self-consolidating concretes. The test results showed that the optimum dosage requirements to obtain a uniform slump flow and visual stability index varied among the four selected admixture sources. The required dosage amount for HRWRAs was highest for the polycarboxylate-ester (PCE) type and lowest for the polycarboxylate-acid (PCA) type. Acceptable flowability plastic viscosity dynamic and static stability, passing ability, and filling ability of self-consolidating concrete can be achieved with the proper dosing of the four studied admixture sources. [ABSTRACT FROM AUTHOR]

Dynamic competition-cooperation models are employed to scrutinize the interplay among products, markets, or services, either in terms of competition or cooperation. Additionally, they serve to predict the behavior of the entities under examination, such as passenger volumes within transportation systems. Utilizing steady-state and asymptotic analyses, researchers delve into the long-term dynamics of these entities. While steady-state analysis delves into equilibrium conditions, asymptotic analysis scrutinizes system behavior as time extends toward infinity. However, the influence of socioeconomic factors, which are external, cannot be disregarded in dynamic competition-cooperation models concerning passenger volumes in transportation systems. These factors typically encompass population dynamics, gross domestic product (GDP), oil prices, unemployment rates, consumer price indices, among others. The primary aim of this study is to assess the stability and asymptotic behavior of dynamic competition-cooperation models in light of economic factors. The investigation reveals that the solutions derived from these models do not exhibit periodic behavior. Rather, the system tends to converge or diverge. Notably, when convergence transpires, it does not converge towards a fixed point but towards a function of the economic factors. This underscores the profound influence of prevailing economic conditions on the behavior of transportation systems. [ABSTRACT FROM AUTHOR]

A multi‐inverter‐fed power system is susceptible to small‐signal instability owing to weak grid influence. This study proposes a black‐box method for small‐signal stability analysis of a multi‐inverter‐fed power system based on Bode diagrams. Not only did it consider the technical confidentiality on the engineering site, but it also took into account the presence of right‐half‐plane (RHP) pole in the aggregated impedance, achieving Nyquist circle acquisition through Bode diagrams. The stability analysis process is thus more accurate, intuitive, and convenient. First, black‐box impedance fitting for a single grid‐connected inverter and impedance aggregation for a multi‐inverter‐fed power system are discussed. Second, the principle of the proposed method is elaborated. Using the Bode diagram, the number of RHP poles of the aggregated impedance and actual number of circles for Nyquist curves are identified. Third, a multi‐inverter‐fed power system is constructed, and the effectiveness of the proposed method is verified using case analysis and hardware‐in‐the‐loop real‐time experiments based on RT‐LAB. Finally, the advantages of the proposed method are revealed by comparing it to the IF method. [ABSTRACT FROM AUTHOR]

Model predictive control (MPC) emerges as an attractive alternative for the control of modular multilevel converters (MMCs) owing to its superior dynamic performance and ease of implementation. Nevertheless, conventional MPC's performance could be further improved by reducing dependence on weighting factors, switching frequency, and computational burden. To achieve these objectives, an arm‐current sensorless MPC is developed for a grid‐interfacing MMC in this article. The MPC is integrated with an arm‐current sensorless reduced switching frequency voltage balance algorithm that requires only m+1 switching vectors (where m= number of submodules per arm) to optimize the cost function. This method does not require knowledge of arm‐current direction to decide the charging and discharging state of the submodule capacitors. The developed control not only reduces the switching frequency of devices but also eliminates the need to sense the arm currents. As a result, it reduces the system's cost, complexity, computational burden, switching losses and provides a more reliable control method for MMCs with superior dynamic performance. Further, the effect of parameter mismatch on the developed MPC's dynamic performance and stability is studied. The developed MPC's effectiveness is validated through both simulation and experimental results and also compared with existing methods under different conditions. [ABSTRACT FROM AUTHOR]