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In this work, we have studied the spin dynamics of a synthetic antiferromagnet (AFM)/heavy metal/ferromagnet double barrier magnetic tunnel junction in the presence of Ruderman–Kittel–Kasuya–Yosida (RKKY) interaction, interfacial Dzyaloshinskii–Moriya (iDM) interaction, Néel field, and Spin–Orbit Coupling (SOC) with different Spin-Transfer Torque (STT). We employ the Landau–Lifshitz–Gilbert–Slonczewski equation to investigate the AFM dynamics of the proposed system. We found that the system exhibits a transition from regular to damped oscillations with the increase in strength of STT for systems with a weaker strength of iDM interaction than RKKY interaction while displaying sustained oscillations for systems having the same order of RKKY and iDM interactions. On the other hand, the systems with sufficiently strong iDM interaction strength exhibit self-similar but aperiodic patterns in the absence of the Néel field. In the presence of the Néel field, the RKKY interaction dominating systems exhibit chaotic oscillations for low STT but display sustained oscillations under moderate STT. Our results suggest that the decay time of oscillations can be controlled via SOC. The system can work as an oscillator for low SOC but displays non-linear characteristics with the rise in SOC for systems having weaker iDM interaction than RKKY interactions. In contrast, opposite characteristics are noticed for iDM interaction dominating systems. We found periodic oscillations under low external magnetic fields in RKKY interaction dominating systems. However, moderate fields are necessary for sustained oscillation in iDM interaction dominating systems. Moreover, the system exhibits saddle-node bifurcations and chaos under moderate Néel field and SOC with suitable RKKY and iDM interactions. In addition, our results indicate that the magnon lifetime can be enhanced by increasing the strength of iDM interaction for both optical and acoustic modes. [ABSTRACT FROM AUTHOR]

This comprehensive study provides a detailed review toward ongoing research on emerging non-volatile memory technologies based nano-oscillators, i.e., from the perspective of materials to applications. Depending on the materials used to fabricate them, the whole class of emerging nano-oscillators has been broadly classified into two categories: (i) electronic and (ii) spintronic oscillators. Moreover, various material-compositions explored for fabricating the oscillatory devices, their physical properties responsible for generating the oscillations, and device architectures are thoroughly reviewed. Furthermore, various advanced computing applications (i.e., realized through these oscillatory devices), such as Internet of Things, neuro-inspired computing, and sensing, are also studied and their key attributes are highlighted. [ABSTRACT FROM AUTHOR]

Velocity autocorrelation functions (VACFs) were calculated using the molecular dynamics method in the TIP4P/2005 and SPC/E water models of 157 464 molecules at temperatures ranging from 250 to 370 K. The large size of the models and the high accuracy of the calculations allow us to reliably compute the long-time tails of the VACFs, showing that they systematically change shape from hydrodynamic (argon-like) at high temperatures to that typical of supercooled liquids at low temperatures. These tails in the range of 2–10 ps can be well fitted by a combination of two power functions: At−3/2 – Bt−β (A, B > 0, β ≈ 2). It is found that the amplitude of the hydrodynamic asymptote, A, approaches zero as the temperature decreases, thereby rendering the negative power-law decay,−Bt−2, the dominant term within the specified time interval. The presence of a negative −Bt−2 decay in the time interval of 2–10 ps determines the specific shape of the VACF long-time tail of water, distinguishing it from ordinary simple liquids. The amplitude B, which is always non-zero, demonstrates a slight increase with rising temperature. At medium temperatures, weak but well-defined damped oscillations are observed on the VACF in the 0.5–2 ps interval. [ABSTRACT FROM AUTHOR]

We report a quantum mechanical method for calculating the momentum distributions of constituent atoms of polyatomic molecules in rotational–vibrational eigenstates. Application of the present theory to triatomic molecules in the rovibrational ground state revealed that oscillatory changes appear on the proton momentum distribution in the nonlinear H2O molecule, while no such modulation is present in the case of an oxygen atom in the linear CO2 molecule. The atomic momentum distributions were analyzed in detail by means of a rigid rotor model, and it was found that the oscillation originates from the quantum-mechanical delocalization of the target atom with respect to the other atoms. [ABSTRACT FROM AUTHOR]

Through a qualitative research with in-depth interviews with Tunisian travellers and netnography on travel related blogs, we aim to investigate how connected technologies modified imaginaries in the travel experience through the (non)sharing behaviour. Findings demonstrate a related expressed paradoxical behaviour swinging between 'self-promotion' and 'evil eye': the former being the desire to be socially visible and included, and the latter is the fear of being jinxed by others. Accordingly, we identify five different travellers' profiles. We conclude that paradoxical social imaginaries of both worldviews can coexist within the travel experience, leading to an incredible complexity and a continuous oscillation between both. [ABSTRACT FROM AUTHOR]

The probability of finding a spherical "hole" of a given radius r contains crucial structural information about many-body systems. Such hole statistics, including the void conditional nearest-neighbor probability functions GV(r), have been well studied for hard-sphere fluids in d-dimensional Euclidean space R d . However, little is known about these functions for hard-sphere crystals for values of r beyond the hard-sphere diameter, as large holes are extremely rare in crystal phases. To overcome these computational challenges, we introduce a biased-sampling scheme that accurately determines hole statistics for equilibrium hard spheres on ranges of r that far extend those that could be previously explored. We discover that GV(r) in crystal and hexatic states exhibits oscillations whose amplitudes increase rapidly with the packing fraction, which stands in contrast to GV(r) that monotonically increases with r for fluid states. The oscillations in GV(r) for 2D crystals are strongly correlated with the local orientational order metric in the vicinity of the holes, and variations in GV(r) for 3D states indicate a transition between tetrahedral and octahedral holes, demonstrating the power of GV(r) as a probe of local coordination geometry. To further study the statistics of interparticle spacing in hard-sphere systems, we compute the local packing fraction distribution f(ϕl) of Delaunay cells and find that, for d ≤ 3, the excess kurtosis of f(ϕl) switches sign at a certain transitional global packing fraction. Our accurate methods to access hole statistics in hard-sphere crystals at the challenging intermediate length scales reported here can be applied to understand the important problem of solvation and hydrophobicity in water at such length scales. [ABSTRACT FROM AUTHOR]

The cytoskeleton, a dynamic network of structural proteins within cells, is essential for cellular deformation and responds to external mechanical cues. Here, based on the structure of the cytoskeleton, combined with the biochemical reactions of the activator RhoA and the inhibitor F-actin, we develop a novel mechanochemical cytoskeleton model to investigate the mechanical behavior of cells. Interestingly, we find that active stress fibers exhibit diverse dynamical modes at specific inhibitor concentration thresholds. The existence of concentration differences and sustained mechanochemical feedback in activators and inhibitors trigger a global oscillation of isolated cells. In addition, under uniaxial and biaxial stretches, activators and inhibitors preferentially diffuse toward the more significantly deformed cytoskeletal elements, and their dynamic interactions regulate the cell to align with the main stretching direction. Our findings, consistent with many experimental results, provide fundamental insights into cytoskeletal remodeling and cellular mechanosensing mechanisms. [ABSTRACT FROM AUTHOR]

Self-sustained electrical oscillations (SEOs) in VO2 films have attracted considerable attention owing to their potential to emulate spiking pulses in neuromorphic circuits. However, triggering stable SEOs and the controlling oscillation frequency remain challenging because the details of circuit operation with VO2-based devices are not yet well understood. In this study, we propose a method to observe SEOs stably in a VO2-based planar device with Au/Ti facing electrodes by introducing a 50 Hz sinusoidal voltage from a curve tracer. The transient aspects, including the onset and collapse of the SEO, were captured, providing clarity on the oscillation frequency range and circuit conditions for the SEOs, which are closely correlated with the device temperature. It became clear that the parallel capacitance not only determined the oscillation frequency but also controlled the current through VO2 just after the insulator–metal transition of VO2, playing a role in triggering stable oscillations. We also successfully observed the transient aspects from in-phase to anti-phase synchronized oscillations in the coupled oscillations. This study advances the experimental procedures and applications of SEOs in VO2-based planar devices. [ABSTRACT FROM AUTHOR]

An experimental evaluation is presented of a two-equation model for the low frequency (< 25 kHz), large amplitude (> --> 100 % of mean) discharge oscillations exhibited by a 9-kW class magnetically shielded Hall thruster. The model is based on a theoretical treatment of the "breathing mode" oscillations in Hall thrusters (Barral and Peradzyński, "A new breath for the breathing mode," IEPC-2009-070) and includes governing equations for fluctuations in the discharge current and the spatially averaged neutral density in the thruster channel. The derivation of the governing equations is reviewed, and the key simplifying assumptions are formulated in terms of comparisons between the magnitudes of relative fluctuations in spatially averaged plasma properties. Experimental measurements are performed of these plasma properties at an operating condition of 300 V discharge voltage and 10 A discharge current. It is found that all quantities of interest such as drift speed, electric field, and temperature fluctuate on the timescale of the low frequency oscillations. However, the relative phasing of these properties combine in such that the key assumptions of the model are satisfied—all but the neutral density and discharge fluctuations can be neglected in the equations for neutral density and current oscillations. A physical interpretation of the validity of the assumptions is presented, and the model is discussed in the context of its extensibility to other operating conditions. The validated model forms the basis for a parametric study presented in Part II of mode transitions and the criterion for these transitions in a magnetically shielded Hall thruster. [ABSTRACT FROM AUTHOR]

Recently, we demonstrated that the local heating of degassed water can generate water vapor microbubbles and induce a rapid flow around the bubble. Although flow generation involves the self-excited oscillation of bubbles at a local heating point, the conditions under which the bubbles oscillate are not fully understood. In this study, the dependence of microbubble size and oscillation frequency on the concentration of non-condensable gases in water was investigated. A continuous-wave laser beam was focused on a β -FeSi 2 thin film, and water was locally heated using the photothermal conversion properties of the film. The results showed that the lower the concentration of non-condensable gases dissolved in water, the smaller the bubble size and the higher the oscillation frequency. Furthermore, it was found that the bubbles oscillate when the amount of non-condensable gas absorbed by the bubbles, i.e., the bubble size, falls below a specific level. This study can provide a new understanding of the bubble oscillation mechanism and lead to the development of fluid control technology using bubbles. [ABSTRACT FROM AUTHOR]

Timed feeding drives adipose browning, although the integrative mechanisms for the same remain unclear. Here, we show that twice-a-night (TAN) feeding generates biphasic oscillations of circulating insulin and leptin, representing their entrainment by timed feeding. Insulin and leptin surges lead to marked cellular, functional, and metabolic remodeling of subcutaneous white adipose tissue (sWAT), resulting in increased energy expenditure. Single-cell RNA-sequencing (scRNA-seq) analyses and flow cytometry demonstrate a role for insulin and leptin surges in innate lymphoid type 2 (ILC2) cell recruitment and sWAT browning, since sWAT depot denervation or loss of leptin or insulin receptor signaling or ILC2 recruitment each dampens TAN feeding-induced sWAT remodeling and energy expenditure. Consistently, recreating insulin and leptin oscillations via once-a-day timed co-injections is sufficient to favorably remodel innervated sWAT. Innervation is necessary for sWAT remodeling, since denervation of sWAT, but not brown adipose tissue (BAT), blocks TAN-induced sWAT remodeling and resolution of inflammation. In sum, reorganization of nutrient-sensitive pathways remodels sWAT and drives the metabolic benefits of timed feeding.

The time-dependent relaxation of a dynamical system may exhibit a power-law behavior that is superimposed by log-periodic oscillations. D. Sornette [Phys. Rep. 297, 239 (1998)] showed that this behavior can be explained by a discrete scale invariance of the system, which is associated with discrete and equidistant timescales on a logarithmic scale. Examples include such diverse fields as financial crashes, random diffusion, and quantum topological materials. Recent time-resolved experiments and molecular dynamics simulations suggest that discrete scale invariance may also apply to hierarchical dynamics in proteins, where several fast local conformational changes are a prerequisite for a slow global transition to occur. Employing entropy-based timescale analysis and Markov state modeling to a simple one-dimensional hierarchical model and biomolecular simulation data, it is found that hierarchical systems quite generally give rise to logarithmically spaced discrete timescales. By introducing a one-dimensional reaction coordinate that collectively accounts for the hierarchically coupled degrees of freedom, the free energy landscape exhibits a characteristic staircase shape with two metastable end states, which causes the log-periodic time evolution of the system. The period of the log-oscillations reflects the effective roughness of the energy landscape and can, in simple cases, be interpreted in terms of the barriers of the staircase landscape. [ABSTRACT FROM AUTHOR]

The semiconductor quantum well based on mercury telluride is characterized by two distinct phases: conventional insulating phase and topological insulating phase with helical edge states. The system undergoes a topological quantum phase transition from one phase to the other, tuned by the critical geometric parameters of the quantum well. It is shown that the quantum states in each phase exhibit distinct flavors of Bloch oscillations, depending strongly on the geometric parameters and crystal momentum of the system. In particular, the group and Berry velocities and the real-space trajectories exhibit pronounced Bloch oscillations. Interestingly, the x - and y -components of the group velocity are interchanged by interchanging their corresponding components of the crystal momentum. In addition, a Gaussian wave packet undergoes distinct time evolution in each quantum phase of the HgTe quantum well. Moreover, the effects of applied in-plane electric and transverse magnetic fields are determined within the framework of Newtonian mechanics, leading to the geometric visualization of such an oscillatory motion. We find that in the presence of both applied in-plane electric and transverse magnetic fields simultaneously, the system undergoes a dynamic phase transition between confined and de-confined states, tuned by the relative strength of the fields. It is argued that the distinct Bloch oscillations originate from the peculiar band structure of HgTe quantum wells in each quantum phase. Furthermore, we find that the direct-current drift velocity in each quantum phase exhibits negative differential conductivity, a hallmark of the Bloch oscillation regime. [ABSTRACT FROM AUTHOR]

Programmable locomotion of molecules inside the carbon nanotube (CNT) has a significant role in controlling the reactions and delivery systems based on nanotubes. Using molecular dynamics (MD) simulations as well as the theoretical approach, we evaluate the oscillation of C60 inside the CNTs that are subjected to strain gradients from both sides. The molecular dynamics simulations are implemented by LAMMPS open-source software. Using this program, the van der Waals (vdW) interactions are established between C60 and nanotube, and the simulations are performed in canonical ensemble. The strain gradient applied on CNT provides the restoring force of the oscillation of C60. The potential energy of fullerene finds the minimum value at the unstrained region of CNT, which makes it the equilibrium point of oscillation. The amplitude of the oscillations is shown to be related to the thermal energy of C60. The frequency of the oscillations depends on the magnitude of the strain gradient applied on the nanotubes. At higher strain gradients of CNTs, we observe the increase in the frequency due to the increase in the restoring force acting on the fullerene molecule. We exploit the strained carbon nanotubes to control the position of C60 inside the nanotube. It has been shown that by changing the strain gradient of CNT, it is possible to steer the locomotion of C60 to different points inside the nanotube. [ABSTRACT FROM AUTHOR]

A high-resolution, temperature oscillation-based probe of physical aging in complex systems is introduced. The Fourier analysis of the measured responses allows one to extract high-order, aging-related nonlinearities that are not accessible via traditional temperature-jump and temperature-ramp procedures. To demonstrate the potential of this oscillatory approach, we analyze the periodic time evolution of glycerol's structural relaxation using shear rheology as a vehicle. Thereby, we access up to the sixth harmonic and detect aging fingerprints within a resolution range of three orders of magnitude for temperature amplitudes of up to 4 K. The even harmonics are present since aging is not symmetrical with respect to the direction of temperature change. The high-order aging coefficients obtained for glycerol are described reasonably well within the Tool–Narayanaswamy–Moynihan formalism. [ABSTRACT FROM AUTHOR]

The understanding of neural excitability and oscillations in single neuron dynamics remains incomplete in terms of global stabilities and the underlying mechanisms for phase formation and associated phase transitions. In this study, we investigate the mechanism of single neuron excitability and spontaneous oscillations by analyzing the potential landscape and curl flux. The topological features of the landscape play a crucial role in assessing the stability of resting states and the robustness/coherence of oscillations. We analyze the excitation characteristics in Class I and Class II neurons and establish their relation to biological function. Our findings reveal that the average curl flux and associated entropy production exhibit significant changes near bifurcation or phase transition points. Moreover, the curl flux and entropy production offer insights into the dynamical and thermodynamical origins of nonequilibrium phase transitions and exhibit distinct behaviors in Class I and Class II neurons. Additionally, we quantify time irreversibility through the difference in cross-correlation functions in both forward and backward time, providing potential indicators for the emergence of nonequilibrium phase transitions in single neurons. [ABSTRACT FROM AUTHOR]

In this study, we applied the conditional nonlinear optimal perturbation (CNOP) method to generate nonlinear fast‐growing initial perturbations for ensemble forecasting, aiming to assess the effectiveness of the CNOP method in improving the forecast skill of climate events. Our findings reveal a significant improvement in the forecast skill of the Indian Ocean Dipole (IOD) within the CNOP ensemble forecast, particularly at long lead times, thereby extending the skilful forecast lead times. Notably, this improvement is more prominent for strong IOD events, with skilful forecast lead times exceeding 12 months, outperforming many current state‐of‐the‐art coupled models. The high forecast skill of the CNOP method is primarily attributed to its ability to capture the uncertainties in the wind anomaly field in the eastern Indian Ocean (EIO) closely associated with IOD evolution. Consequently, CNOP ensemble members exhibit significant deviations from the control forecast, resulting in a large ensemble spread encompassing IOD evolution. Furthermore, a comparison with the climate‐relevant singular vectors (CSV) method in terms of IOD and El Niño–Southern Oscillation (ENSO) predictions reveals the superior performance of the CNOP ensemble forecast. Despite the initial perturbations for ensemble forecasting being generated aimed at improving IOD forecast skill, the CNOP method significantly improves the forecast skill of both IOD and ENSO events, with a greater improvement for ENSO. Additionally, the CNOP ensemble forecast system provides more reliable estimates of forecast uncertainties and exhibits higher reliability with increasing lead times. In conclusion, the CNOP method effectively captures the nonlinear physical processes of climate events and improve the forecast skill. [ABSTRACT FROM AUTHOR]

• Amplitude and synchrony of 40-Hz ASSR was decreased by sound pressure change. • Decrease of amplitude and synchrony depended on magnitude of sound pressure change. • Transient 40-Hz ASSR desynchronization might be an index of change detection. A periodic sound with a fixed inter-stimulus interval elicits an auditory steady-state response (ASSR). An abrupt change in a continuous sound is known to affect the brain's ongoing neural oscillatory activity, but the underlying mechanism has not been fully clarified. We investigated whether and how an abrupt change in sound intensity affects the ASSR. The control stimulus was a train of 1-ms clicks with a sound pressure level (SPL) of 70 dB at 40 Hz for 1000 ms. In addition to the control stimulus, we applied six stimuli with changes consisting of a 500-ms train at 70 dB followed by a 500-ms similar train with louder clicks of 75, 80, or 85 dB or weaker clicks of 55, 60, or 65 dB. We obtained the magnetoencephalographic responses from 15 healthy subjects while presenting the seven stimuli randomly. The two-dipole model obtained for the 40-Hz ASSR in the control condition was applied to all of the stimulus conditions for each subject, and then the time–frequency analysis was conducted. We observed that both the amplitude and the inter-trial phase coherence of the 40-Hz ASSR transiently decreased and returned to the steady state after the change onset, i.e., the desynchronization of 40-Hz ASSR. The degree of desynchronization depended on the magnitude of the change regardless of whether the sound intensity increased or decreased, which might be a novel neurophysiological index of cerebral response driven by a change in the sensory environment. [ABSTRACT FROM AUTHOR]

We investigate the oscillatory behavior of solutions of second‐order linear differential equations with impulses. These equations can be categorized into two types: canonical and non‐canonical. This study examines the canonical and non‐canonical impulsive differential equations in connection with the famous Leighton‐type oscillation theorem. The well‐known theorem states that every solution of (r(t)x′)′+p(t)x=0,t≥t0,$$ {\left(r(t){x}&#x0005E;{\prime}\right)}&#x0005E;{\prime }&#x0002B;p(t)x&#x0003D;0,\kern0.30em t\ge {t}_0, $$ where r$$ r $$ and p$$ p $$ are continuous with r(t)>0$$ r(t)>0 $$, is oscillatory if ∫t0∞dtr(t)=∞(canonical case),(*)$$ \kern3.4cm \int_{t_0}&#x0005E;{\infty}\frac{\mathrm{d}t}{r(t)}&#x0003D;\infty \kern0.30em \left(\mathrm{canonical}\ \mathrm{case}\right),\kern3.4cm \left(\ast \right) $$ and ∫t0∞p(t)dt=∞.(**)$$ \kern4.6cm \int_{t_0}&#x0005E;{\infty }p(t)\kern0.1em \mathrm{d}t&#x0003D;\infty .\kern4.3cm \left(\ast \ast \right) $$ This pioneering work of Leighton has received considerable attention since its inception, and hence, it has been extended to various types of equations, including delay differential equations, dynamic equations, and impulsive differential equations. There are also studies generalizing the Leighton oscillation theorem when the condition (∗)$$ \left(\ast \right) $$ fails, that is, when the equation is of non‐canonical type. Our work focuses on refining the Leighton oscillation theorem to treat the canonical and non‐canonical cases. By doing so, we correct, supplement, and enhance the current literature on the oscillation theory of differential equations with impulses. Examples are also given to illustrate the significance of the obtained results. [ABSTRACT FROM AUTHOR]

• Brain activity includes both oscillatory and aperiodic components. • Dopamine may modulate these components differently. • Haloperidol influences oscillatory, but not aperiodic, activity. • Oscillatory activity modulation occurs across the brain. The electrical activity of the brain, characterized by its frequency components, reflects a complex interplay between periodic (oscillatory) and aperiodic components. These components are associated with various neurophysiological processes, such as the excitation-inhibition balance (aperiodic activity) or interregional communication (oscillatory activity). However, we do not fully understand whether these components are truly independent or if different neuromodulators affect them in different ways. The dopaminergic system has a critical role for cognition and motivation, being a potential modulator of these power spectrum components. To improve our understanding of these questions, we investigated the differential effects of this system on these components using electrocorticogram recordings in cats, which show clear oscillations and aperiodic 1/f activity. Specifically, we focused on the effects of haloperidol (a D2 receptor antagonist) on oscillatory and aperiodic dynamics during wakefulness and sleep. By parameterizing the power spectrum into these two components, our findings reveal a robust modulation of oscillatory activity by the D2 receptor across the brain. Surprisingly, aperiodic activity was not significantly affected and exhibited inconsistent changes across the brain. This suggests a nuanced interplay between neuromodulation and the distinct components of brain oscillations, providing insights into the selective regulation of oscillatory dynamics in awake states. [ABSTRACT FROM AUTHOR]

Mitigating traffic jams is a critical step for the betterment of the urban transportation system, which comprises a large number of interconnected routes to form an intricate network. To study the distinct features and complexities of vehicular flow, a network consisting of multiple-loops with a single intersection is considered a directed weighted graph. The governing equations for individual loop densities are derived using the principle of mass conservation, considering a data-driven flow-density relationship. Firstly, we examine the stability of a double-loop network and explore the traffic behavior using the macroscopic fundamental diagram (MFD) for different sets of parameters. Utilizing popular techniques of nonlinear dynamics, the existence of bistability, bifurcations, oscillations, and switching dynamics is demonstrated in the case of the triple-loop network. Further, bistability is characterized by plotting the basin of attraction diagram for the coexisting attractors. Our study reveals that an increase in the number of loop lines enriches the dynamical properties of vehicular traffic flow. It is observed that depending upon the initial density configuration, a loop network can show various phases, namely free flow, stop-and-go traffic jams, and loop congestion. Additionally, we show the presence of period-2 orbits in the case of the quadruple-loop system. [ABSTRACT FROM AUTHOR]

In order to realize stable propagation of the ethylene-air rotating detonation wave with less velocity deficit in the annular combustion chamber, a series of experiments have been carried out while changing the combustor width (i.e. 10 mm, 15 mm, 25 mm, and a hollow combustor), mass flow rate of air, and equivalence ratio. The air and ethylene are supplied into the combustor through a slot-orifice impinging injection scheme, where air is injected through a slot with a height of 0.5 mm and ethylene is supplied by 160 orifices with a diameter of 0.35 mm. Experimental results indicate that four propagation modes have been obtained, i.e. the single wave mode, the sawtooth wave mode, the periodic oscillation mode, and the deflagration mode. The sawtooth wave mode and the periodic oscillation mode are considered unstable modes. In the single wave mode, the average propagation velocity of rotating detonations in the annular combustion chamber with a combustor width of 15 mm is between 1121 and 1215 m/s. The minimum velocity deficit is 21.9%, and the relative standard deviation of the propagation velocity is less than 5%, which is much lower than the experimental results of other studies utilizing ethylene and air in the annular combustors. In addition, the reasons may lead to the failure of producing rotating detonations have been analyzed. The effects of the chemical reactivity on the generation of rotating detonation waves have been demonstrated by installing a convergent nozzle at the exit of the combustor. [ABSTRACT FROM AUTHOR]

Over the past three decades, a great deal of attention has been paid to the study of perisomatic inhibition and perisomatic inhibitory basket cells. A growing body of experimental evidence points to the leading role of perisomatic inhibitory cells in the generation of oscillatory activity in various frequency ranges. Recently the link between the activity of basket cells and complex behavior has been demonstrated in several laboratories. However, all this is true only for one type of perisomatic inhibitory interneuron—parvalbumin-positive basket cells. Nevertheless, where parvalbumin-positive basket cells are found, there is another type of basket cell, cholecystokinin-positive interneurons. These two types of interneurons share a number of common features: they innervate the same compartments of target neurons and they often receive excitation from the same sources, but they also differ from each other in the synchrony of their GABA release and expression of receptors. The functional role of cholecystokinin-positive basket cells in oscillatory activity is not so obvious. They were thought to be involved in theta oscillations, however recent measurements in free moving animals have put some doubts on this hypothesis. Therefore, an important question is, whether these two types of basket cells work synergistically or perform opposing actions in functional networks? In this mini-review, we attempt to answer this question by putting forward the idea that these two types of basket cells are functionally united as two entities of the same network, and their opposing actions are necessary to maintain rhythmogenesis in a "healthy", physiological range. [ABSTRACT FROM AUTHOR]

Many hairy mammals perform rapid oscillations of their body, called wet dog shakes, to remove water and irritants from their back hairy skin. The somatosensory mechanisms that underlie this behavior are unclear. We report that Piezo2-dependent mechanosensation mediates wet dog shakes evoked by water or oil droplets applied to back hairy skin of mice. Unmyelinated C-fiber low-threshold mechanoreceptors (C-LTMRs) were activated by oil droplets, and their optogenetic activation elicited wet dog shakes. Ablation of C-LTMRs attenuated this behavior. Moreover, C-LTMRs synaptically couple to spinoparabrachial neurons, and optogenetically inhibiting spinoparabrachial neuron synapses and excitatory neurons in the parabrachial nucleus impaired both oil droplet– and C-LTMR–evoked wet dog shakes. Thus, a C-LTMR–spinoparabrachial pathway promotes wet dog shakes for removal of water and mechanical irritants from back hairy skin. [ABSTRACT FROM AUTHOR]

Atmospheric rivers (ARs) are characterized by intense lower tropospheric plumes of moisture transport that are frequently responsible for midlatitude wind and precipitation extremes. The prediction of ARs at subseasonal-to-seasonal (S2S) timescales is currently at a low level of skill, reflecting a need to improve our understanding of their underlying sources of predictability. Based on 20 year hindcast experiments from the Geophysical Fluid Dynamics Laboratory's SPEAR S2S forecast system, we evaluate the S2S prediction skill of AR activities in the northern winter. Higher forecast skill is detected for high-frequency AR activities (3–7 days/week) compared to low-frequency AR activities (1–2 days/week), even though the occurrence rate of high-frequency ARs exceeds that of low-frequency ARs. For the first time, we have applied the Average Predictability Time technique to the SPEAR system to identify the three most predictable modes of AR in the North Pacific sector. These modes can be attributed to the influences of the El Niño–Southern Oscillation, the Pacific North American pattern, and the Arctic Oscillation. S2S AR forecast skill in western United States is modulated by various phases of large-scale variability. This study highlights potential windows of opportunity for operational S2S AR forecasting. [ABSTRACT FROM AUTHOR]

Spin oscillators relying on ferromagnetic (FM) materials have been limited to frequency generation in the range of only a few gigahertz. In contrast, antiferromagnetic (AFM) material-based oscillators have a potential for beyond gigahertz range oscillations. However, the use of AFM oscillators is limited due to challenges in detecting and controlling magnetic orientation. This arises from the inherent lack of significant net magnetization in AFMs. This work focuses on exploring the dynamic characteristics of a spin Hall nano-oscillator (SHNO) that addresses these challenges by leveraging the inter-layer exchange interaction between AFM and FM layers. The proposed design demonstrates stable and power-efficient oscillation in the FM layer, relying on the dynamics of the AFM layer. The proposed AFM–FM-based SHNO design achieves a maximum frequency of 16.4 GHz at ISOT = 180 μA. Furthermore, considering the thermal effects at 300 K, the stable oscillation frequency is achieved at 15.94 GHz. The proposed device exhibits robust and tunable oscillations over a wide frequency range with a power consumption of 4 μW. Moreover, this oscillator achieves 3.35× and 2.44× higher oscillation frequency compared to spin torque nano-oscillators and conventional SHNO-based oscillators, respectively. [ABSTRACT FROM AUTHOR]

Solar heating is important for many applications but less attractive for concepts requiring intermittent heating, such as ionic thermoelectric supercapacitors (ITESCs). However, the heating process even at constant solar illumination can be converted to temperature oscillations through water infiltration and evaporation. Here, this process is demonstrated for a carbon nanotube‐cellulose membrane and used to induce temporally varying temperature gradients across an ITESC, which enables continuous operation through repeated charge and discharge cycles. A temperature variation of 10 K can be generated on the top electrode, which leads to a variation in the temperature difference across the ITESC of 7.5 K. Precise control over charge and discharge durations can be achieved by adjusting the volume and interval of the added water. The concept of temporarily adjusting temperatures by evaporative cooling may be extended to create intermittent heating also for other heat sources that are typically constant. [ABSTRACT FROM AUTHOR]

Alpha oscillations are associated with various psychiatric disorders, with many studies focusing on the prefrontal cortex, where transcranial alternating current stimulation (TACS) is applied in the alpha frequency band. This approach often involves selecting individualized alpha frequencies to resonate with their endogenous alpha oscillations. While strong alpha oscillations (8–13 Hz) are typically induced when the eyes are closed, they can also occur during the resting state with eyes open. However, it remains unclear whether these alpha oscillations share a common neural generation mechanism. Exploring which of these alpha oscillations is more suitable as a stable alpha peak frequency is a question of significant interest. Therefore, to systematically study this issue, we specifically collected resting-state electroencephalographic (EEG) data from the prefrontal region of 40 individuals, under both eyes-open and closed- eye conditions, with multiple follow-ups extending up to nine months. Through spectral analysis on each person's entire dataset and averaging the results, we observed a significant positive correlation between the alpha-band power in the eyes-open and the eyes-closed states, in terms of both absolute power and relative power. Further analysis revealed that this correlation was primarily contributed by the periodic activity within the alpha band. Upon modelling the oscillatory components, we discovered distinct differences in the oscillatory characteristics-such as number of the alpha sub-oscillations between the eyes-open state and the eyes-closed state. Our study is the first to systematically explored the relationship between alpha oscillations in the prefrontal cortex in the eyes-open and eyes-closed states, identifying both shared part of the neural generation mechanism and some distinct neural mechanisms that are unique to each state. [ABSTRACT FROM AUTHOR]

We consider an abstract linear wave equation with a time-dependent dissipation that decays at infinity with the so-called scale invariant rate, which represents the critical case. We do not assume that the coefficient of the dissipation term is smooth, and we investigate the effect of its oscillations on the decay rate of solutions. We prove a decay estimate that holds true regardless of the oscillations. Then we show that oscillations that are too fast have no effect on the decay rate, while oscillations that are in resonance with one of the frequencies of the elastic part can alter the decay rate. In the proof we first reduce ourselves to estimating the decay of solutions to a family of ordinary differential equations, then by using polar coordinates we obtain explicit formulae for the energy decay of these solutions, so that in the end the problem is reduced to the analysis of the asymptotic behavior of suitable oscillating integrals. [ABSTRACT FROM AUTHOR]

Photobiomodulation (PBM) is a non-invasive neuromodulation technique for the brain. Low-intensity near-infrared light (1–500 mw) has demonstrated the ability to improve memory in Alzheimer's disease (AD) model mice, suggesting its potential for AD treatment. However, the impact of PBM on neural oscillations in the hippocampal region affected by AD remains unknown. In this study, AD model mice were subjected to PBM for 60 days and then tested using novel object recognition behavior (NOR) experiments. During behavioral experiments, local field potential signals (LFP) of the mice was recorded using a single electrode in the CA1 region to analyze memory ability and neural oscillation characteristics. The results revealed that mice stimulated with PBM exhibited significantly higher new object differentiation indices compared to the Sham group (p < 0.01). Furthermore, PBM stimulation led to a significant increase in relative power and sample entropy of theta and gamma bands (p < 0.01). The coupling intensities of θ-low-γ and θ-high-γ were also significantly higher in the PBM group compared to the Sham group (p < 0.01). In conclusion, these findings suggest that PBM may improve memory ability in AD mice through regulation of neural oscillation characteristics, providing a theoretical basis for utilizing PBM as a treatment modality for Alzheimer's disease. [ABSTRACT FROM AUTHOR]

An environment interacting with a quantum system can enhance transport through the suppression of quantum effects responsible for localization. In this paper, we study the interplay between bulk dephasing and a linear potential in a boundary-driven tight-binding chain. A linear potential induces Wannier-Stark localization in the absence of noise, while dephasing induces diffusive transport in the absence of a tilt. We derive an approximate expression for the steady-state current as a function of both dephasing and tilt which closely matches the exact solution for a wide range of parameters. From it, we find that the maximum current occurs for a dephasing rate equal to the period of Bloch oscillations in the Wannier-Stark localized system. We also find that the current displays a maximum as a function of the system size, provided that the total potential tilt across the chain remains constant. Our results can be verified in current experimental platforms and represents a step forward in analytical studies of environment-assisted transport. [ABSTRACT FROM AUTHOR]

In this article, the homoepitaxial regrowth of AlGaN on AlGaN templates fabricated via chemical mechanical polishing (CMP) on periodically aligned AlN nanopillars is reported on. These templates are lattice relaxed according to X‐Ray diffraction reciprocal space mapping measurements, with a low dislocation density of ≈3 × 108 cm−2. However, the AlGaN surface has hillocks exceeding 104 cm−2. Contrastingly, no hillocks are observed on the homoepitaxially regrown AlGaN on the CMP–AlGaN template and after the UV‐B laser diode (LD) layer structure is crystallized and grown on the homoepitaxially regrown AlGaN. Furthermore, when this wafer is processed for LD fabrication, room‐temperature pulsed oscillation is confirmed in the UV‐B region at a wavelength of 296 nm. The turn‐on voltage and operating voltage also reduce by ≈2 V. [ABSTRACT FROM AUTHOR]

Knowledge of the effects of climate modes on the equatorial intermediate current (EIC) remains limited. This paper investigates exceptional events of the EIC in the Indian Ocean and their relationships with climate modes at various time scales by using observations, reanalysis outputs, and a continuously stratified linear ocean model (LOM). A mooring at 80°E from 2015 to 2019 revealed four exceptionally strong EIC events, occurring in 2015 July–August (JA), 2016 January–February (JF), 2016 JA, and 2019 JF. Component analysis revealed that these exceptional events are attributed to the co-occurrence of the seasonal components peaking during JF and JA, as well as the larger current anomalies associated with intraseasonal and interannual components. In the intraseasonal band, the Madden–Julian oscillation (MJO) generates a significant EIC anomaly through a 40–50-day process involving equatorial waves. The MJO exerts a substantial effect when the amplitude of the MJO index exceeds 1 and the oscillation is in phase 4. In the interannual band, El Niño–Southern Oscillation and the Indian Ocean dipole (IOD) can each independently contribute to the EIC anomaly. This contribution initiates during the mature phase and persists throughout the subsequent year. Concurrent occurrences of these effects can lead to larger interannual anomalies. Notably, El Niño–positive IOD (El Niño–pIOD) and La Niña–negative IOD (La Niña–nIOD) synergies are most pronounced in August and in January of the following year. Significance Statement: Four exceptional equatorial intermediate current (EIC) events characterized by strong eastward velocities are observed in the Indian Ocean during 2015–19. This study explored their underlying dynamics and their relationships with climate modes. Climatologically, the EIC has seasonal cycles with peaks in January–February and July–August, which is helpful in producing exceptional EIC events. However, the occurrence of these events is attributed to the intensity of the intraseasonal and interannual variability that occurs around the seasonal cycle peaks. This study revealed that climate modes, including the Madden–Julian oscillation (MJO), El Niño–Southern Oscillation (ENSO), and Indian Ocean dipole (IOD), contribute to exceptional EIC events in the intraseasonal and interannual bands. Notably, their influence is comparable, albeit contingent upon specific conditions. [ABSTRACT FROM AUTHOR]

Based on the two-fluid model, we successfully simulated the film casting process of the polymer solution system and observed the unique response wave of the film thickness and the concentration via applying perturbation. We identify that this instability pattern is essentially the product under the coupling effect of viscoelastic stress and osmotic pressure from fluctuations on different scales, which causes it to exhibit biperiodic characteristics. We call this new instability mode known as dual-mode draw resonance instability. Among them, the concentration oscillation predominates, thereby limiting the critical draw ratio Drc of the system. Through sorting out the molecular image of the polymer concentration response to perturbation, the relevant parameters are extracted, and the law of their influence on the Drc further verifies our conclusion and provides guidance for actual production. [ABSTRACT FROM AUTHOR]

Despite music's omnipresence, the specific neural mechanisms responsible for perceiving and anticipating temporal patterns in music are unknown. To study potential mechanisms for keeping time in rhythmic contexts, we train a biologically constrained RNN, with excitatory (E) and inhibitory (I) units, on seven different stimulus tempos (2–8 Hz) on a synchronization and continuation task, a standard experimental paradigm. Our trained RNN generates a network oscillator that uses an input current (context parameter) to control oscillation frequency and replicates key features of neural dynamics observed in neural recordings of monkeys performing the same task. We develop a reduced three-variable rate model of the RNN and analyze its dynamic properties. By treating our understanding of the mathematical structure for oscillations in the reduced model as predictive, we confirm that the dynamical mechanisms are found also in the RNN. Our neurally plausible reduced model reveals an E-I circuit with two distinct inhibitory sub-populations, of which one is tightly synchronized with the excitatory units. [ABSTRACT FROM AUTHOR]

Background: Deep brain stimulation (DBS) targeting the subthalamic nucleus (STN) has emerged as a potent treatment for alleviating motor symptoms in Parkinson's disease (PD). Despite its effectiveness, the impact of high frequency STN-DBS on cerebellar oscillations remains unclear, posing an intriguing challenge for neural modulation. Given the direct and indirect connections between the STN and cerebellum, we investigated whether STN-DBS affects cerebellar oscillations. Objective: To observe the effects of STN-DBS on cerebellar oscillations in patients with PD. Methods: We recruited 15 PD patients receiving STN-DBS. Electroencephalographic (EEG) signals were recorded from cerebellar regions during resting-state conditions in both the OFF-DBS and STN-DBS conditions. Our analyses centered on spectral features, particularly theta and beta oscillations, guided by prior research and correlation tests to investigate the relationship between oscillatory changes and motor symptom severity. Results: In the mid-cerebellar (Cbz) region, we observed a significant increase in the relative power in all frequency bands, including theta and beta oscillations during STN-DBS, showing the global effect of DBS. Importantly, the correlation results indicated significant associations between mid-cerebellar (Cbz) beta power during the OFF condition and motor severity, which were not evident during STN-DBS. Interestingly, correlations between beta power and motor severity were not observed at the mid-occipital (Oz) and mid-frontal (Cz) regions. Notably, signal similarity analyses demonstrated no evidence of volume conduction effects between the mid-cerebellar (Cbz) and nearby mid-occipital (Oz) regions. Conclusions: While these findings provide valuable insights into the complex interplay between STN-DBS and neural oscillations, further research is essential to decipher their precise functional significance and clinical implications. Understanding these intricacies may contribute to the optimization of DBS therapies for PD. Plain Language Summary: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment for reducing motor symptoms in Parkinson's disease (PD). However, its effects on brain activity, specifically in the cerebellum, are not well understood. This study aimed to investigate how STN-DBS affects cerebellar brain waves in PD patients. We recruited 15 PD patients undergoing STN-DBS and recorded their brain activity including cerebellar region using EEG. We compared the brain wave patterns during periods when the DBS was turned OFF and when it was turned ON, focusing on specific brain wave frequencies (theta and beta). The results showed a significant increase in brain wave power across all frequencies in the mid-cerebellar region during STN-DBS. Additionally, there was a strong link between beta power in the cerebellum and motor symptom severity when DBS was OFF, which was not present when DBS was ON. This relationship was specific to the cerebellum and not found in other brain regions. The findings suggest that STN-DBS significantly alters cerebellar brain activity and that these changes are related to improvements in motor symptoms. However, more research is needed to fully understand the functional significance and potential clinical applications of these findings for optimizing DBS treatment in PD patients. [ABSTRACT FROM AUTHOR]

Summary: To address the problem of bursting oscillations in doubly fed induction generator (DFIG) systems under external disturbances, an analysis method based on fast‐slow dynamics and a control strategy based on an adaptive high‐order differential feedback controller (AHODFC) is proposed. The fast‐slow dynamics analysis method was adopted to reveal the formation mechanism of bursting oscillations from the DFIG system owing to the multi‐timescale coupling effect of perturbation, that is, the oscillation is in the form of a bursting oscillation with alternating large‐amplitude oscillation and micro‐amplitude oscillation. A control strategy based on the AHODFC with a high‐order differentiator (HOD) was proposed to address the problem of bursting oscillations in the DFIG system. The control strategy of the AHODFC has smooth control‐rate characteristics, does not depend on the exact mathematical model of the controlled system, and has good applicability and robustness to various types of bursting oscillations caused by different disturbance amplitudes and system parameters. Our simulations verified the feasibility and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In the context of rapidly rising sea levels over the north Indian Ocean, the decadal variations play significant role and predicting them is of utmost important to the society. The present study evaluates the quality of all the available retrospective decadal sea level predictions from the state-of-the-art climate models of the Coupled Model Intercomparison Project (CMIP) Phase 6 (CMIP6). The models are skilful in predicting the sea level over the tropical Indo-Pacific for the lead year 1 and thereafter the skill persists mainly over the western Indian Ocean regions. Most of the models exhibit significant skill in the Arabian Sea region at higher leads including 2–5 years and 6–9 years. Half of the models display higher sea level prediction skill over the Arabian Sea at lead year 2–5, compared to lead year 1. Taking into account of the close association between the Indian Ocean decadal sea level variations and the decadal climate variability in the Pacific and Atlantic, the skill of models in predicting the Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO) up to a decade is also assessed in this study. The AMO is better predicted in most of the models up to lead year 9, whereas only few models display skill in predicting the PDO. Skilful representations of strong cross equatorial flow and convergence of southerly winds towards the Arabian Sea region are noted in the CMIP6 predictions, which are responsible for better sea level prediction skill over the Arabian Sea. This study highlights that the better representation of AMO in the models has primarily contributed to the skilful sea level predictions over the Arabian Sea region. [ABSTRACT FROM AUTHOR]

This work presents an experimental realization of a ring scheme of nonlinear threshold controlled unidirectionally coupled (N = 3) second-order autonomous type oscillating systems. The originality of this work lies in having the threshold controller as the nonlinear element of the dynamical system and as the coupling element to form a ring circuit using these systems. The advantage of this coupling is getting tuning of frequency (multi-frequency) of the ring from a few hertz to kilohertz along with the observation of a periodic rotating wave pattern by varying one of the parameter values of the system, in terms of either changing the resistor value (gain) in the coupling path or changing the threshold value of the threshold controller or both. The results explored through this experimental study are confirmed by numerically simulated results, obtained using MATLAB coding- simulink and MULTISIM software. The symmetrical and asymmetrical aspects of the flexible threshold coupling are also studied and the observed interesting experimental and numerical results are presented. [ABSTRACT FROM AUTHOR]

The aim of this paper is to establish improved uniform error bounds under H α / 2 -norm (1 < α ≤ 2) for the long-time dynamics of the high-dimensional nonlinear space fractional sine-Gordon equation (NSFSGE) by a Lawson-type exponential integrator Fourier pseudo-spectral (LEI-FP) method. Firstly, a Lawson-type exponential integrator method is used to discretize the time direction. Then, the Fourier pseudo-spectral method is applied to discretize the space direction. We rigorously prove that the equation is energy conservation in a continuous state. Regularity compensation oscillation (RCO) technique is employed to strictly prove the improved uniform error bounds at O ε 2 τ in temporal semi-discretization and O h m + ε 2 τ in full-discretization up to the long-time T ε = T / ε 2 ( T > 0 fixed), respectively. To obtain the convergence order h m in space, we only need to directly prove it instead of proving that the numerical solution is H m + α / 2 -norm bounded as before. Complex NSFSGE and oscillatory NSFSGE are also discussed. This is the novel work to construct the improved uniform error bounds for the long-time dynamics of the high-dimensional nonlinear space fractional Klein-Gordon equation with non-polynomial nonlinearity. Finally, numerical examples in two-dimension and three-dimension are provided to confirm the improved error bounds, and we find drastically different evolving patterns between NSFSGE and the classical sine-Gordon equation. [ABSTRACT FROM AUTHOR]

Neural oscillations are electrophysiological indicators of synchronous neuronal activity in the brain. Recent work suggests aberrant patterns of neuronal activity in patients with poststroke aphasia. Yet, there is a lack of systematic explorations of neural oscillations in poststroke aphasia. Investigating changes in the dynamics of neuronal activity after stroke may be helpful to identify neural markers of aphasia and language recovery and increase the current understanding of successful language rehabilitation. This review summarizes research on neural oscillations in poststroke aphasia and evaluates their potential as biomarkers for specific linguistic processes. We searched the literature through PubMed, Web of Science, and EBSCO, and selected 31 studies that met the inclusion criteria. Our analyses focused on neural oscillation activity in each frequency band, brain connectivity, and therapy‐induced changes during language recovery. Our review highlights potential neurophysiological markers; however, the literature remains confounded, casting doubt on the reliability of these findings. Future research must address these confounds to confirm the robustness of cross‐study findings on neural oscillations in poststroke aphasia. There is a lack of systematic explorations of neural oscillations in poststroke aphasia. Investigating changes in the dynamics of neuronal activity after stroke may help to identify neural markers of aphasia and language recovery. Our study also increases the current understanding of successful language rehabilitation. [ABSTRACT FROM AUTHOR]

We present exponential wave integrator Fourier pseudospectral (EWI‐FP) methods and establish their error estimates of the fully discrete schemes for the Dirac equation in the massless and nonrelativistic regime. This regime involves a small dimensionless parameter where 0<ε≤1$$ 0<\varepsilon \le 1 $$, and ε$$ \varepsilon $$ is inversely proportional to the speed of light. The solution exhibits highly oscillatory behavior in time and rapid wave propagation in space in this regime. Specifically, the time oscillations have a wavelength of O(ε)$$ O\left(\varepsilon \right) $$, while the spatial oscillations have a wavelength of O(1)$$ O(1) $$, with a wave speed of O(ε−1)$$ O\left({\varepsilon}^{-1}\right) $$. We employ (symmetric) exponential wave integrators for temporal derivatives and Fourier spectral discretization for spatial derivatives. We rigorously derive the error bounds which explicitly depend on the mesh size h$$ h $$, the time step τ$$ \tau $$ and the small dimensionless parameter ε$$ \varepsilon $$. The error estimates for the EWI‐FP methods demonstrate that their meshing strategy requirement (ε$$ \varepsilon $$‐scalability) necessitates setting h=O(1)$$ h=O(1) $$ and τ=O(ε)$$ \tau =O\left(\varepsilon \right) $$ when 0<ε≪1$$ 0<\varepsilon \ll 1 $$. Finally, some numerical examples are provided to validate the error bounds. [ABSTRACT FROM AUTHOR]

In this paper, an adaptive fuzzy sliding mode controller utilizing a high-gain observer is proposed to address the aeroelastic instabilities of a novel nonlinear aircraft wing section under unsteady aerodynamics. The controller is designed to effectively mitigate high amplitude oscillations that arise in the system and enable aircraft to operate within an extended flight envelope. Additionally, the proposed controller utilizes output feedback to estimate the states and nonlinear dynamics of the model. The two-degree-of-freedom (2-DOF) nonlinear aeroelastic system describes the pitch and plunge motions of the wing section equipped with trailing and leading edge control surfaces. The resulting aeroelastic model, including the structural stiffness nonlinearities and the unsteady aerodynamic model, is based on Wagner's indicial function. The simulation results demonstrate the effectiveness of the suggested controller in suppressing the flutter phenomenon and improving the flight speed range. Further, the proposed controller accurately estimates the states of the model and successfully drives them to the origin despite the presence of disturbances and uncertainties. [ABSTRACT FROM AUTHOR]

Shallow reservoirs are ubiquitous in hydraulic engineering. Predicting the properties of the flow field in such reservoirs is instrumental to inform their design, operation, and maintenance. In previous research, oscillating jets were experimentally observed in rectangular shallow reservoirs, and we assess here the performance of a simple analytical model to predict the frequency of the dominating jet oscillation mode(s). The model couples the evaluation of the reservoir natural frequencies with the Rossiter feedback loop formula. The analytical predictions are compared against experimental observations by reanalyzing an existing data set. In many cases, the model predictions match the observations. Remaining discrepancies may result from experimental uncertainties, which could be reduced in future tailored laboratory tests, or from the dimensionless vortex celerity value used by the feedback loop model, which was not assessed experimentally. [ABSTRACT FROM AUTHOR]

In this paper, we study an initial-boundary value problem of three-dimensional (3D) compressible isentropic magneto-micropolar fluid equations with Coulomb force and slip boundary conditions in a bounded simply connected domain, whose boundary has a finite number of two-dimensional connected components. We derive the global existence and uniqueness of classical solutions provided that the initial total energy is suitably small. Our result generalizes the Cauchy problems of compressible Navier-Stokes equations with Coulomb force [S. Liu, X. Xu and J. Zhang, Global well-posedness of strong solutions with large oscillations and vacuum to the compressible Navier-Stokes-Poisson equations subject to large oscillations and non-flat doping profile, J. Differ. Equ. 269 (2020) 8468-8508] and compressible MHD equations [H. Li, X. Xu and J. Zhang, Global classical solutions to 3D compressible magnetohydrodynamic equations with large oscillations and vacuum, SIAM J. Math. Anal. 45 (2013) 1356-1387] to the case of bounded domains although tackling many surface integrals caused by the slip boundary condition are complex. The main ingredient of this paper is to overcome the strong nonlinearity caused by Coulomb force, magnetic field, and rotation effect of micro-particles by applying piecewise-estimate method and delicate analysis based on the effective viscous fluxes involving velocity and micro-rotational velocity. [ABSTRACT FROM AUTHOR]

The hydrodynamic coefficients on a deeply submerged solid/porous disk subjected to forced heave oscillation have been investigated in analytical and experimental approaches. The analytical model is developed by means of a matched eigenfunction expansion method (MEEM) using a quadratic relationship between the pressure drop and traversing fluid velocity across the porous disk. For the improvement and validation of the analytical model, a series of experiments with the solid/porous disks is conducted for various porosities, Keulegan-Carpenter (KC) numbers, and oscillation periods. In addition to the small-scale hole vortices across the porous disk, the effect of edge vortices on the hydrodynamic coefficients is empirically implemented by curve-fitting with experimental data. The inclusion of edge vortices in the analytical model results in good agreement with experimental data of the damping coefficient for a deeply submerged disk. However, there are some discrepancies in the added mass, with noticeable differences occurring in the disk with low porosity. [ABSTRACT FROM AUTHOR]

The grid-forming virtual synchronous generator (GFVSG) not only employs a first-order low-pass filter for virtual inertia control but also introduces grid-connected active power (GCAP) dynamic oscillation issues, akin to those observed in traditional synchronous generators. In response to this, an improved strategy for lead-lag filter based GFVSG (LLF-GFVSG) is presented in this article. Firstly, the grid-connected circuit structure and control principle of typical GFVSG are described, and a closed-loop small-signal model for GCAP in GFVSG is established. The causes of GCAP dynamic oscillation of GFVSG under the disturbances of active power command as well as grid frequency are analyzed. On this basis, the LLF-GFVSG improvement strategy and its parameter design method are given. Finally, the efficiency of the proposed control strategy in damping GCAP dynamic oscillations under various disturbances is verified using MATLAB simulations and experimental comparison results. [ABSTRACT FROM AUTHOR]

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