Velocity Difference Research Articles

GLP-1R gene polymorphisms and metabolic traits during childhood and adolescence: The EPOCH study.

This is the first study to examine the association between variants of the glucagon-like-peptide-1 receptor gene (GLP-1R) and metabolic characteristics among youth. We explored separate associations of three GLP-1R polymorphisms (rs10305420, rs6923761, and rs1042044) with BMI trajectories and markers of glucose-insulin homeostasis. Mixed models examined associations between GLP-1R polymorphisms and trajectories of BMI. Linear models examined associations of GLP-1R polymorphisms with glucose and insulin concentrations across OGTT, insulin sensitivity (HOMA2-IR), insulin secretion (insulinogenic index and HOMA2-%B), and beta cell function (oral disposition index). Rs10305420 and rs6923761, but not rs1042044, were associated with growth and metabolic characteristics in early life. Rs6923761 genotype GG was associated with faster BMI growth velocity, when compared to carriers of the minor allele (difference in velocity [95% CI]: 0.16 kg/m2/year [0.07, 0.24] at age 10), which led to significantly higher average BMI by age 16 (average difference [95% CI]: 1.29 kg/m2 [0.22, 2.37]). Rs10305420 CC and rs6923761 GG genotypes had higher HOMA2-IR (β[95% CI]: 1.19%[1.06, 1.32] and 1.13%[1.01, 1.26], respectively) compared to minor allele carriers. Rs10305420 CC had higher HOMA2-%B (β[95% CI]: 1.09%[1.01, 1.17]), and higher stimulated insulin secretion at 30-minutes (β[95% CI]: 27.62 uIU/mL [3.00, 25.24]) and 120-minutes (β[95% CI]: 18.94 uIU/mL [1.04, 36.84), when compared to carriers of the minor allele. GLP-1R polymorphisms were associated with faster BMI growth across development, and lower estimated insulin sensitivity and higher compensatory insulin secretion during adolescence. GLP-1R polymorphisms should be considered in future pediatric studies of genetic susceptibility for obesity and diabetes.

Noise Reduction of Velocity Measured by Frequency-Supervised Combined Doppler Sonar Using an Adaptive Sliding Window and Kalman Filter

Velocity is fundamental information for ocean engineering. It is difficult for traditional Doppler sonar to provide accurate and wide-range velocity measurement information with a short time lag. Therefore, a frequency-supervised combined Doppler sonar system using an adaptive sliding window and Kalman filter is proposed. In this method, the initial value of the integer ambiguity is calculated based on the average value of the conventional Doppler sonar. The change value of the integer ambiguity is calculated by the difference of the adjacent velocities measured by coherent Doppler sonar. The velocity of combined Doppler sonar is calculated by the cumulative result of the initial and change values of integer ambiguities. Finally, the velocity bias due to the error of the integer ambiguity calculation is corrected by the frequency supervision using the Kalman filter in a sliding time window under different signal-to-noise ratios. The experimental results show that the proposed method is more accurate than the conventional Doppler sonar, has a wider measurement range compared with coherent Doppler sonar, and suppresses the impulsive noise well. The frequency-supervised combined Doppler sonar using an adaptive sliding window and Kalman filter can provide accurate and precise velocities with a short time lag over a wide range of signal-to-noise ratios.

Lift force on a spherical droplet in a viscous linear shear flow

We study numerically the flow around a spherical droplet set fixed in a linear shear flow with moderate shear rates ( $Sr\leq 0.5$ , $Sr$ being the ratio between the velocity difference across the drop and the relative velocity) over a wide range of external Reynolds numbers ( $0.1<{{Re}}\leq 250$ , ${{Re}}$ based on the slip velocity and the viscosity of the external fluid) and drop-to-fluid viscosity ratios ( $0.01\leq \mu ^\ast \leq 100$ ). The flow structure, the vorticity field and their intrinsic connection with the lift force are analysed. Specifically, the results on lift force are compared with the low- ${{Re}}$ solution derived for droplets of arbitrary $\mu ^\ast$ , as well as prior data at finite ${{Re}}$ available in both the clean-bubble limit ( $\mu ^\ast \to 0$ ) and the solid-sphere limit ( $\mu ^\ast \to \infty$ ). Notably, at ${{Re}}=O(100)$ , the lift force exhibits a non-monotonic transition from $\mu ^\ast \to 0$ to $\mu ^\ast \to \infty$ , peaking at $\mu ^\ast \approx 1$ . This behaviour is related to an internal three-dimensional flow bifurcation also occurring under uniform-flow conditions, which makes the flow to evolve from axisymmetric to biplanar symmetric. This flow bifurcation occurs at low-but-finite $\mu ^\ast$ when the internal Reynolds number ( ${{Re}}^i$ , based on the viscosity of the internal fluid) exceeds approximately 300. In the presence of shear, the corresponding imperfect bifurcation enhances the extensional rate of the flow in the wake. Consequently, the streamwise vortices generated behind the droplet can be more intense compared with those behind a clean bubble. Given the close relation between the lift and these vortices, a droplet with ${{Re}}=O(100)$ and $\mu ^\ast \approx 1$ typically experiences a greater lift force than that in the inviscid limit.

Bifurcation analysis and control of the full velocity difference model with delayed velocity difference.

With the increase in the number of urban vehicles, various traffic problems have gradually emerged. Studying the causes of traffic congestion and proposing effective mitigation strategies have important practical significance. This paper proposes a macroscopic traffic flow model that considers the delayed speed difference. This paper applies nonlinear bifurcation to describe and predict nonlinear traffic phenomena on highways from the perspective of global stability of the traffic system. By using the traveling wave transformation, the proposed car-following model is converted into a macroscopic traffic flow model. Next, this paper employs the linear stability analysis to find the bifurcation points of the stability transition in the traffic system, exploring the qualitative characteristics of the inhomogeneous continuous traffic flow model. Theoretical derivations demonstrate the existence of bifurcation points within the model. Additionally, this paper plots the density-time space diagrams and phase plane diagrams of the system to visually present the sudden changes in traffic flow as variable parameters pass through these bifurcation points. Finally, this paper designs a feedback controller to regulate the Hopf bifurcation, aiming to delay or eliminate the occurrence of Hopf bifurcations in the stochastic system.

Effects of total temperature and equivalence ratio on n-decane/air two-phase rotating detonation wave

The Eulerian–Lagrangian method is used to conduct the numerical simulation of the non-premixed two-phase rotating detonation wave (RDW) fueled by n-decane/air. The stratified spray detonation transient phenomena, as well as the effects of total temperature (850, 900, 1000 K) and equivalence ratio (0.5, 0.7, 1.0) on the RDW dynamics and propagation characteristics are discussed in detail. The results indicate that the velocity difference caused by separate injection of fuel and air generates the low-temperature zone behind the oblique shock wave, which hinders the direct contact between the droplets and the detonation products. Droplets in the refilled zone are broken by the shear effect and evaporate in high total temperature air, forming the stratified distribution structure of droplets and vapor. In addition, the coupling–decoupling–recoupling dynamic mechanism is observed between the leading shock front and the heat release zone, which leads to the local decoupling of RDW during the propagation. Moreover, the spatial variation of high-pressure zones at the leading shock front leads to multiple leading shock fronts and transverse pressure waves. It is revealed that the increase in total temperature broadens the lower boundary of equivalence ratio to obtain two-phase RDW. RDW velocity and velocity deficit are insensitive to the total temperature in the considered parameter range. However, the increase in the total equivalence ratio not only improves the mean velocity significantly but also enlarges the velocity deficit. With the increasing total temperature and equivalence ratio, the stability of pressure becomes worse. Furthermore, the stability of velocity declines with the increasing equivalence ratio at the total temperature of 1000 K.

Detonation flows of explosives containing compressible inert particles

The present study employs a combination of numerical and analytical techniques to examine the detonation flows of explosives containing compressible inert particles. A two-phase numerical model incorporating the compressibility of the particles is developed, and the two-phase detonation process is simulated under the Lagrangian framework, where the explosive and the particles are treated as a fluid and discrete spheres, respectively. For small velocity difference between phases, a perturbation method is utilized for the analysis of the dynamics of the detonation front, the detonation product, and the particles. The effects of the particles' compressibility and material density are examined in detail. The results show that the material density of the particles exerts a linear influence on the detonation flow of the explosive, while the effects of the particle compressibility are much more complex. An increase in the particle's material density or compressibility can reduce the velocities of both the detonation front and the flowing-stagnant boundary. The jump of the particle volume fraction across the detonation front relies on the particle compressibility. For more compressible particles, the particle volume fraction exhibits a non-monotonic behavior in the flowing region. A concise scaling law is also obtained for the velocity difference between phases. The present research provides a quantitative prediction to the effects of compressible particles on the detonation flows of explosives.

Numerical simulation of the dual-loop different velocity air curtain system in the operating room

The problem of cross-infection between patients and surgeons in the operating room had been widely concerned by the international community. The purpose of this study had been to explore the potential of a Dual-loop Different Velocity Air Curtain System (DDVACS) being applied in the operating room to reduce cross-infection. In this study, the performance of the system was studied using the computational fluid dynamics (CFD) numerical simulation method, with the operating conditions of different air supply velocities inside and outside being set. The RNG k-ε model, Discrete Phase Model (DPM), and Species Transport model were used to simulate the air distribution, particle diffusion, and virus diffusion. The main research results showed that, when the DDVACS was operated at an inner air supply velocity of 0.24 m/s and an outer air supply velocity of 0.45 m/s, the virus concentration in the surgical area had decreased by 89%, the particulate matter concentration in the surgical area had decreased by 78.08%, but the deposition of particulate matter had increased by 21.62%. This study concluded that DDVACS had been found to effectively reduce the concentration of cross-infection. Finally, the velocity difference between the inner and outer sides was controlled within 2 times. This setting had been arranged to make the DDVACS work better. This study's contribution was to further verify the application of the DDVACS in operating rooms, providing a new perspective and empirical support for related fields and possessing certain practical application value.

Investigation of internal flow and mixing characteristics in dual-orifice atomizers

Dual-orifice atomizers have been developed to overcome the limitations of simplex atomizers—where “simplex” refers to having only a single flow channel—which cannot adjust flow rates over a wide range. This study explores the internal flow and mixing characteristics of dual-orifice atomizers using the Volume of Fluid method. The effects of four key parameters—primary post thickness, primary recess length, secondary swirl number, and mass flow rate ratio—on flow dynamics and atomizer performance, particularly exit film thickness and spray cone angle, are investigated. The results reveal that, before mixing, the low-pressure region created by the swirling flow inside the secondary nozzle increases the primary flow angle and reduces the thickness of the primary liquid film. After mixing, the velocity difference between the primary and secondary flows enhances atomization by promoting greater instability. The impingement position of the primary liquid film is influenced by recess and the low-pressure region inside the secondary nozzle, with longer recess lengths shifting the impingement point upstream. Increases in secondary swirl number, mass flow rate ratio, and primary post thickness further enlarge the low-pressure region, causing the impingement point to move upstream. The mixing regime is defined by the impingement position, with tip mixing creating velocity stratification that increases the instability. The performance of dual-orifice atomizers depends on the impingement position, resulting mixing regime, and secondary flow's swirl intensity. These findings provide valuable insights for optimizing atomizer design to improve performance.

Postural stability in patients with vestibular migraine and probable vestibular migraine in the absence of acute vestibular symptoms

PurposeTo investigate postural stability in patients with vestibular migraine (VM) and probable vestibular migraine (PVM) in the absence of acute vestibular symptoms. MethodsWe retrospectively reviewed the medical records at our balance disorder clinic. The 30 consecutive VM patients and 25 consecutive PVM patients enrolled in this study all underwent foam posturography. 194 healthy control subjects with no history of dizziness or balance dysfunction was also enrolled. Multiple regression analyses were performed to see whether subjects' age, sex, or diagnosis (VM, PVM and control) were associated with the posturographic findings. Dependent variables were the mean velocity of the center of pressure movement (velocity) and the area enclosed by the center of pressure movement (area) in Fixed/Open, Fixed/Closed, Foam/Open and Foam/Closed conditions, the Romberg's ratio in Velocity/Fixed, Velocity/Foam, Area/Fixed and Area/Foam conditions, and the foam ratio in Velocity/Open, Velocity/Closed, Area/Open and Area/Closed. Independent variables were sex (male, female), age, and diagnosis (VM, PVM and control). ResultsVM and PVM patients showed significantly increased velocity and area compared to healthy controls with and without foam rubber. VM and PVM patients showed significantly lower foam ratios compared to healthy controls in velocity and area, both with open and closed eyes. On the other hand, there were no significant differences in velocity or area, Romberg's ratio or foam ratio between VM patients and PVM patients in any conditions. ConclusionsBoth VM and PVM patients had more postural instability than healthy controls. There were no differences in postural stability between VM and PVM patients.

Influence of insulating and conducting walls on magnetohydodynamic flow in a suddenly expanded channel: A numerical study

ABSTRACT In this study, we conducted numerical simulations using the robust code AnuPravaha. The code’s performance was rigorously validated by benchmarking it against a range of standard cases, including Shercliff and Hunt’s cases. The same AnuPravaha code is used to identify the effect of conduction and insulating walls on a suddenly expanded channel for low Hartmann number ranging from 10–100 and Reynolds number ranging from 100–500. The results finding indicate that at a low Hartmann number Ha ≤ 40, the effect on the flow profile remains negligible. As the Hartmann number increases Ha > 40, it generates a more crescent-shaped profile, reducing the centerline flow velocity and increasing it near the side walls. It is also observed that variations in pressure drop are minimal within the low Hartmann number range of Ha = 10–30 but become very significant for a higher Hartmann number (Ha > 30). For a change in Hartmann number from Ha = 20 to Ha = 40, the pressure drop rises by 212% and at Hartmann number from Ha = 50 to Ha = 100, it increases by 284% indicating an amplification effect on the magnetic field at a higher Hartmann number. The pressure drop achieved in Insulating walls is far lesser than the conduction walls as insulating walls don’t allow any current-wall interaction. It is found that by using insulating walls the average pressure drop is reduced by about 94%. At a fixed Reynolds number, insulating walls yield higher outlet velocities than conduction walls due to lower Lorentz force resistance which modifies the volumetric heating effects. Increasing Hartmann number reduces the velocity difference between both types of walls.

Swirling instability of viscous liquid jets with axial shear effect in gas surroundings

Linear instability analysis of a viscous swirling liquid jet surrounded by ambient gas is carried out by considering the significant influence of axial shear effect. The jet azimuthal flow is assumed as a Rankine vortex, and the non-uniform velocity distribution in the jet axial direction is approximated by parabolic and error functions. The enhancement of jet rotation is found to promote the predominant mode with larger azimuthal wavenumbers, and the mode transition is decided by the competition between centrifugal force and axial shear stress. Subsequently, the influence of the axial shear effect is examined through changing the degree of shear stress and the thickness of the gas velocity boundary layer. It is found that an increase of jet average velocity or surface velocity in the axial direction leads to the predominant mode transition to smaller azimuthal wavenumbers, due to the combined effects of shear stress and gas pressure perturbation. A larger velocity difference between ambient gas and liquid jet also promotes the predominant modes with smaller azimuthal wavenumbers, and the physical mechanism is attributed to gas pressure perturbation. Phase diagrams of different azimuthal modes are given and compared with the study of Kubitschek & Weidman (J. Fluid Mech., vol. 572, 2007, pp. 261–286), where a static swirling column without axial shear stress was considered. The strengthened axial shear effect is found to delay the transition of predominant modes with the increase of angular velocity. Experimental studies considering the swirling jets with different axial velocities are further carried out, which validate the theoretical findings. Different instability mechanisms and their transition rules are also identified through energy budget analysis. This study is expected to give scientific guidance on understanding the instability mechanisms of the swirling jets that widely exist in natural phenomena and engineering applications.

Incorporating mean-field velocity difference in a continuum macroscopic traffic flow model for adverse road conditions

In developing countries, the quality of driving infrastructure, specifically road conditions, is often suboptimal, presenting challenges and limitations for motorists. However, current traffic flow models have limitations in addressing problems caused by poor road networks. To address this issue, a new macroscopic traffic flow model has been proposed in this study that considers mean-field velocity differences on roads with suboptimal conditions. A thorough model derivation of this new macroscopic traffic flow model is presented. The study establishes crucial stability conditions, providing profound insights into traffic dynamics across diverse scenarios. Numerical simulations are presented to demonstrate the model's ability to capture shock waves, rarefaction waves, and local cluster effects. The study results offer new insights into traffic dynamics in adverse road conditions and enforce the need to enhance road infrastructure to alleviate congestion and enhance road safety.

Experimental Investigation on Velocity Field in Subterranean Water Flow Under Different Size of Gravel

Direct measurement of flow velocities within subterranean layer is important for predicting subterranean flow. The authors conducted a study on the velocity field of subterranean water flow by directly measuring the flow velocity within the subterranean layer using crushed stone to form a gravel mount. Namely, they directly measured subterranean flow velocities for five different sizes of gravels (5.3 mm, 16.5 mm, 25.5 mm, 47.5 mm, and 92.4 mm) and showed for the first time how the time-averaged flow velocity and standard deviation vary with the size of the gravels. The velocity field including turbulent intensity in the subterranean layer was revealed, and the flow field of the subterranean flow depends on the size of the gravels that make up the gravel mount. The relationship between the configuration of the gravel mount, the water surface profile, and the velocity field within the subterranean layer allowed a discussion of the vertical distribution of time-averaged velocities and standard deviations, as well as stream wise changes in the subterranean layer. From the results of time-averaged velocity and turbulent intensity (here, standard deviation) in the subterranean layer for different sizes of gravels, it is possible to estimate the velocity field of subterranean water flow formed by the grain size distribution of the depositing gravels and the difference in water level. In other words, by clarifying the velocity field of subterranean water flow consisting of different gravel sizes, it may be possible to evaluate the subterranean function of the sand and gravel zone deposited by transported gravels.

Numerical analysis of solute transport and longitudinal dispersion coefficients in vegetated flow

Reasonable estimates of longitudinal dispersion coefficients are essential for predicting solute dispersion processes. However, the current knowledge of solute dispersion processes in vegetated waters is limited. In this work, we coupled a refined hydrodynamic model with scalar transport equations to simulate the flow field and dispersion process of solutes in water under the effect of vegetation. First, the proposed numerical model was verified using laboratory experiments, revealing the excellent performance of the coupled model in complex conditions. Eight different cases were subsequently simulated to analyse the effects of the upstream flow rate and vegetation height on the streamwise velocity, solute concentration, and longitudinal dispersion coefficients. The simulation results show that the upstream flow variation exerts a marked effect on the streamwise velocity and flow field within the vegetation zone, with a velocity difference within the shear layer reaching 54.7 % for an upstream flow of 0.018 m3·s-1. The height of the vegetation affects both the velocity profile and solute dispersion. Placing emergent vegetation upstream can enhance solute dispersion in the longitudinal direction. The correlation analysis reveals that the longitudinal dispersion coefficients obtained using the routing producer are close to those determined using the theoretical method, with correlation coefficients reaching 0.75. This work presents the appropriate application range and parameters that must be considered in deriving formulas for longitudinal dispersion coefficients.

Sex differences in the role of AKAP12 in behavioral function of middle-aged mice

A-kinase anchoring protein 12 (AKAP12) is a key scaffolding protein that regulates cellular signaling by anchoring protein kinase A (PKA) and other signaling molecules. While recent studies suggest an important role for AKAP12 in the brain, including cognitive functions, its role in middle-aged mice and potential sex differences are not fully understood. Therefore, this study investigated the effects of AKAP12 on cognitive and exploratory behavior in middle-aged mice, focusing on sex differences. Cognitive function was assessed using the spontaneous Y-maze test and the novel object recognition test (NORT). No significant sex differences in cognitive function were found in middle-aged C57BL/6J mice; however, female mice showed greater exploratory behavior during the NORT. In addition, both middle-aged male and female Akap12 knockout (KO) mice performed similarly to wild-type (WT) mice in the Y-maze test, but had lower discrimination indices in the NORT, suggesting a potential role for AKAP12 in short-term memory. Notably, exploratory behavior was suppressed in female Akap12 KO mice compared to WT mice, whereas male Akap12 KO mice did not show this effect. There were no significant differences in movement distance and velocity during the Y-maze test and NORT between WT and KO mice of either sex. These results indicate that AKAP12 affects cognitive function and exploratory behavior in middle-aged mice and that these effects differ between sexes.

Neural processing of rhythmic speech by children with developmental language disorder (DLD): An EEG study

Abstract Sensitivity to rhythmic and prosodic cues in speech has been described as a precursor of language acquisition. Consequently, atypical rhythmic processing during infancy and early childhood has been considered a risk factor for developmental language disorders. Despite many behavioural studies, the neural processing of rhythmic speech has not yet been explored in children with developmental language disorder (DLD). Here we utilise EEG to investigate the neural processing of rhythmic speech by 9-year-old children with and without DLD. In the current study, we investigate phase entrainment, angular velocity, power, event related potentials (ERPs), phase-amplitude coupling (PAC) and phase-phase coupling (PPC), at three frequency bands selected on the basis of the prior literature, delta, theta and low gamma. We predicted a different phase of entrainment in the delta band in children with DLD, and also greater theta power, atypical cross-frequency coupling and possibly atypical gamma-band responses. Contrary to prediction, children with DLD demonstrated significant and equivalent phase entrainment in the delta and theta bands to control children. However, only the control children showed significant phase entrainment in the low gamma band. The children with DLD also exhibited significantly more theta and low gamma power compared to the control children, and there was a significant gamma-band difference in angular velocity between the two groups. Finally, group resultant phase analyses showed that low-frequency phase (delta and theta) affected gamma oscillations differently by group. These EEG data show important differences between children with and without DLD in the neural mechanisms underpinning the processing of rhythmic speech. The findings are discussed in terms of auditory theories of DLD, particularly Temporal Sampling theory.

Effects of laminar burning velocity to friction velocity ratio on turbulent premixed flame-wall interaction within turbulent boundary layers

Direct numerical simulation of flame-wall interaction (FWI) for two flame configurations under different laminar burning velocity to nonreacting wall friction velocity ratio, SL/uτNR, have been performed. The first configuration considered is a V-flame in a turbulent channel flow with isothermal inert walls and represents oblique wall interaction. The second configuration is representative of head-on interaction (HOI) of a planar flame interacting with a wall in a fully developed turbulent boundary layer. In the case of the V-flame with SL/uτNR=0.4, a smaller flame angle is obtained when compared with that of the V-flame with SL/uτNR=0.7. This is a consequence of the differences in the turbulent burning velocities between the two V-flame cases, where the case with SL/uτNR=0.4 has a lower turbulent burning velocity when compared with that of the case with SL/uτNR=0.7. By contrast, the ratio of turbulent to laminar burning velocity is higher for the SL/uτNR=0.4 HOI case when compared to the corresponding HOI case with SL/uτNR=0.7. The flame orientations with respect to the streamwise component of velocity and wall-normal direction in addition to the SL/uτNR values have been found to have a significant impact on the variations of wall heat flux, wall shear stress, and wall friction velocity in premixed FWI within turbulent boundary layers. The behaviors of nondimensional streamwise velocity, u+, and nondimensional temperature using wall units, T+, have also been investigated for different SL/uτNR ratios and it is found that the standard log-law profiles in the case of u+ and T+ are not valid for the two configurations and the two SL/uτNR ratios considered. Published by the American Physical Society 2024

Gait alteration during turning while walking in older adults with benign paroxysmal positioning vertigo

Background Older adults with Benign Paroxysmal Positioning Vertigo (BPPV) may present with unsteadiness that affects gait patterns. Objective This study investigated the spatiotemporal gait parameters and indicators of turning difficulty during the Timed Up and Go (TUG) test in older adults with BPPV. Methods This case-controlled study collected data from older adults aged 65 and above with BPPV, young adults with BPPV and older adults without BPPV. Postural stability and self-perception of stability were measured using the Functional Gait Analysis and the Malay version of the Dizziness Handicap Inventory, respectively. The spatiotemporal gait parameters were recorded using a camera. The one-way ANOVA test was used for statistical analysis. Results Older adults with BPPV presented with alteration in gait parameters (time and number of steps) compared to older adults without BPPV and adults with BPPV during the TUG test (p < 0.05). During the straight walking tasks of the TUG test, there were significant differences in stride length and velocity between the three groups (p < 0.05). Older adults with BPPV presented with less pivoting and took longer time and more steps to complete the turning phase of the TUG. Conclusions The findings suggest that gait performance was compromised in older adults with BPPV.

State Estimation for Quadruped Robots on Non-Stationary Terrain via Invariant Extended Kalman Filter and Disturbance Observer.

Quadruped robots possess significant mobility in complex and uneven terrains due to their outstanding stability and flexibility, making them highly suitable in rescue missions, environmental monitoring, and smart agriculture. With the increasing use of quadruped robots in more demanding scenarios, ensuring accurate and stable state estimation in complex environments has become particularly important. Existing state estimation algorithms relying on multi-sensor fusion, such as those using IMU, LiDAR, and visual data, often face challenges on non-stationary terrains due to issues like foot-end slippage or unstable contact, leading to significant state drift. To tackle this problem, this paper introduces a state estimation algorithm that integrates an invariant extended Kalman filter (InEKF) with a disturbance observer, aiming to estimate the motion state of quadruped robots on non-stationary terrains. Firstly, foot-end slippage is modeled as a deviation in body velocity and explicitly included in the state equations, allowing for a more precise representation of how slippage affects the state. Secondly, the state update process integrates both foot-end velocity and position observations to improve the overall accuracy and comprehensiveness of the estimation. Lastly, a foot-end contact probability model, coupled with an adaptive covariance adjustment strategy, is employed to dynamically modulate the influence of the observations. These enhancements significantly improve the filter's robustness and the accuracy of state estimation in non-stationary terrain scenarios. Experiments conducted with the Jueying Mini quadruped robot on various non-stationary terrains show that the enhanced InEKF method offers notable advantages over traditional filters in compensating for foot-end slippage and adapting to different terrains.

Study on synergistic efficiency of zonal water distribution and wind-conducting structure of high-level water-collecting natural draft wet cooling towers under crosswinds

The high-level water collection cooling tower has broad application prospects in the field of nuclear power, but the high crosswind environment will significantly reduce the flow and heat transfer performance of the high-level water collection natural ventilation wet cooling tower (HNDWCT). So a synergistic model of zoned water distribution and wind guiding structures is proposed in this paper. Numerical simulations were performed to compare and analyze the cooling tower’s flow and heat transfer characteristics in the synergistic and traditional models under a 0–10 m/s crosswind environment. The results show that the synergistic model increases the inlet air flow of the natural ventilation high-rise cooling tower by 7.8–46 %, reduces the standard deviation of the inlet air velocity by 0.22–0.81, and reduces the outlet water temperature by 0.32–3.51 K, which improves the cooling performance of the cooling tower.