Horizontal And Vertical Research Articles

Estimation of tsunami direction and horizontal velocity field from tsunami magnetic field.

During tsunamis, the interaction between moving seawater and the Earth's magnetic field generates a magnetic field detectable by electromagnetic sensors located on land or on the seafloor. In this study, we introduce new methods for estimating tsunami propagation direction and horizontal velocity fields using tsunami magnetic field data. We derive a transfer function that establishes a relationship between the tsunami magnetic field and the velocity field, emphasizing the alignment between the horizontal magnetic field and the tsunami's propagation direction. This transfer function was validated with data from the 2009 Samoa and 2010 Chile tsunamis. Our findings show that tsunami horizontal velocities and directions can be accurately determined from these magnetic fields. This advancement enables the use of tsunami magnetic fields to provide comprehensive data for tsunami warning systems and to improve the inversion of tsunami seismic sources.This article is part of the theme issue 'Magnetometric remote sensing of Earth and planetary oceans'.

Mixing of Top‐Down and Bottom‐Up Diffusing Reactive Tracers Within the Ocean Mixed Layer and Its Application to Autumn Phytoplankton Blooms

AbstractThe mixing of reactive tracers within the ocean mixed layer, phytoplankton transported downwards from the sea surface and nutrients transported upwards from the mixed layer depth (MLD), is investigated using large eddy simulation coupled to a Lagrangian plankton model. The study focuses on how vertical and horizontal heterogeneity in tracer distribution is generated and how it influences an autumn phytoplankton bloom. The vertical gradient appears in the profiles of horizontal mean phytoplankton and nutrient concentrations, P and N, and it reduces phytoplankton production by photosynthesis compared to the cases with uniform distributions. The reduction ratio decreases as the mixed‐layer mean N increases, but it remains relatively insensitive to other conditions such as MLD, surface forcing, stratification below the mixed layer, and the initial N. Phytoplankton and nutrient concentrations show a negative correlation in the horizontal plane, which becomes stronger with increasing depth. Its contribution to plankton production by photosynthesis is negligible, however, because the correlation is weak near the sea surface and the reaction time scale is much longer than the turbulent mixing time scale. It is also found that the vertical gradients of P and N are smaller, and the negative correlation is stronger in the convective mixed layer than in the shear‐driven mixed layer. A simple box plankton model, which takes into account the mixing process of tracers, is proposed and used to investigate how mixing affects the prediction of an autumn phytoplankton bloom.

A033: Estimating Three-Dimensional Ground Reaction Forces in Running Using Inertial Sensors at Different Segments

Background/Purpose: The acquisition of three-dimensional ground reaction forces (3D-GRF) during running is crucial for monitoring and assessing running performance. However, limitations often arise in collecting 3D-GRF due to equipment and environmental constraints. Inertial sensors are gaining popularity in running applications because of their convenience, broad applicability, and cost-effectiveness. This study aimed to utilize an inertial sensor for gathering kinematic data during running, establish a high-precision neural network model for continuous 3D-GRF estimation, and investigate estimation variances across different body segments. Method: A total of thirty-three college students (17 male, 16 female) participated in this study. Kinematic and kinetic data were concurrently recorded using inertial sensors placed on the lower back, lateral thigh, anterior lower leg, and dorsum of the foot, while three-dimensional force plates were utilized during running at speeds of 8/10/12 km/h. The dataset was partitioned into training, validation, and test sets at a ratio of 24:3:6. A Long Short-Term Memory Neural Network (LSTM) was developed for training to predict 3D-GRF. Evaluation metrics included coefficients of determination, Root Mean Square Error (RMSE), and Normalized Root Mean Square Error (NRMSE). Models customized for specific body segments underwent a nine-fold cross-validation procedure, employing one-way ANOVA to evaluate estimation variances across different anatomical sites. Results: Estimation outcomes at different sites indicated optimal estimation accuracy at the right thigh. The coefficients of determination for Anteroposterior (AP)-GRF, Mediolateral (ML)-GRF, and Vertical (V)-GRF were 0.81±0.00, 0.55±0.14, and 0.97±0.02, respectively. RMSE values were 0.06±0.01BW, 0.06±0.01BW, and 0.14±0.03BW. Significant variances were observed between the right thigh and other sites in the horizontal plane (p < 0.05). The results from the test set showed correlation coefficients, RMSE, and NRMSE for AP-GRF, ML-GRF, and V-GRF: AP-GRF, 0.94±0.01, 0.06±0.01BW, 4.78%±0.50%; ML-GRF, 0.83±0.08, 0.10±0.01BW, 9.70%±2.41%; V-GRF, 0.99±0.00, 0.14±0.02BW, 2.79%±0.24%. Conclusion/Discussion: 1. The neural network model developed in this study demonstrated exceptional accuracy across three dimensions, facilitating continuous estimation of 3D ground reaction forces during running. Correlation coefficients surpassed 0.8 in every direction, with RMSE values below 0.2BW and NRMSE below 5%. 2. Estimation results from inertial sensors positioned at different sites exhibited diverse levels of disparity. The lateral thigh emerged as the most proficient location for estimation, with the lower back excelling in vertical ground reaction force estimation but displaying comparatively weaker performance in horizontal ground reaction force estimation.

Designing a vibration energy harvester for several directions of excitation in planar motion

Abstract Harvesting energy from a mechanical vibration source is always challenging and comes with drawbacks, especially when the vibration input changes direction very often. This research proposes a novel design to harvest energy from a planar mechanical vibration source no matter its direction of oscillation. To achieve this, a spiral beam with a tip mass is designed to be flexible to various directions of the vibration input in a horizontal plane, which is orthogonal to the direction of gravity. An approximate analytical investigation is first performed. Numerical simulations are then conducted using commercial FEA software and the results are in good agreement with the analytical approach. Numerical simulations show that the tip mass acts symmetrically in the plane, although the system is not geometrically symmetric. To experimentally validate the proposed configuration, a 3D-printed prototype device was manufactured and attached to a shaker, which induced a vibrating motion for the tests. A piezoelectric patch was attached to the curved beam to generate electrical energy and measurements of produced open-circuit voltages were taken for different directions of the exciting vibration.

Oscillations of the Concrete Pump Boom in the Vertical Plane

Oscillations of the Concrete Pump Boom in the Vertical Plane

Attitude motion and nonlinear free-surface deformation of stone-skipping over shallow water

Stone-skipping is a common yet complex motion that involves rigid-body dynamics and fluid–structure interaction (FSI). While many computational fluid dynamics methods are used to simulate the interaction between a stone and fluid, little research has been done to consider the stone, fluid, and fluid boundary as a whole in a simulation. This study, focuses on the attitude motion and free-surface deformation of stone-skipping over shallow water to investigate how the boundary effect of FSI impacts ricochet behaviors. Initially, we establish an iteration framework for the stone-skipping FSI issue based on a weakly compressible smoothed particle hydrodynamics (SPH) method with a Riemann solver. We conduct particle-independence verification and simulate several cases under varying water heights. Additionally, we analyze and compare ricochets in deep and shallow cases with different incident angles and initial pitch angles. The numerical results demonstrate that in shallow flow scenarios, the “comma-shaped” high-pressure area is compressed by the stone and the fluid boundary, leading to a more moderate variation in pitch angle. Stone-skipping in shallow water typically covers a shorter distance and reaches a lower height compared to deep water cases. Changes in the incident angle show that shallow water hinders successful skipping. Futhermore, different initial pitch angles reveal that water height directly impact the stone's trajectory in both horizontal and vertical directions. These highlight the connection between motion patterns and parameters, offering a reliable numerical prediction for the stone-skipping problem using the Riemann SPH method.

A study on the structural characteristic of tire clamp using a new design method

The development of the new energy automobile industry has driven the development of the tire industry, and the development of the tire industry has put forward higher requirements for the handling and storage efficiency of tires. In this paper, through the discussion of the new tire synchronous fixture, the double parallel four-bar mechanism is introduced. The mechanism has the advantages of horizontal extension and contraction, and avoids the deviation in the vertical direction. In order to be better applied to the handling and storage of tires and further applied in other fields, this paper obtains the relationship between rod length and stroke through the kinematic analysis of double parallel four-bar mechanism, establishes a compact structure size table of common size, and carries out practical application simulation. The accuracy of size is verified by mechanical simulation. Through the relationship established in this paper and the compact structure size table, we can quickly and easily find the appropriate size of the double parallel four-bar mechanism according to the demand. Through the study of its structural characteristics, we can easily find the scene where it can be applied, so as to promote the universality of the application of the double parallel four-bar mechanism.

Deep Learning Image Segmentation Based on Adaptive Total Variation Preprocessing.

This article proposes a two-stage image segmentation method based on the MS model, aiming to enhance the segmentation accuracy of images with complex structure and background. In the first stage, in order to obtain the smooth approximate solution of the image by minimizing the energy functional, an anisotropic regularization term formed by the combination of the gradient operator and an adaptive weighted matrix is introduced. Different weights in both horizontal and vertical directions can be provided by the adaptive weighting matrix according to the gradient information, so that the curve diffuses along the directions of local feature tangents of the objects. In addition, information irrelevant to the image target can be filtered out by the adaptive weighting matrix, thus reducing the interference of complex background. The alternating direction method of multipliers (ADMMs) is employed to solve the convex optimization problem in the first stage. In the second stage, the smoothed image obtained in the first stage is segmented by the deep learning method. By comparing with some traditional methods and deep learning methods, the results demonstrate that not only has good perceptual quality been achieved by this segmentation method, but also superior evaluation metrics have been obtained.

Four-dimensional flow characteristics of air-entrained turbulent impinging waterjet onto quiescent water surface

This paper presents a time-resolved three-dimensional (4D) flow fields measurement of the continuous phase of a turbulent impinging jet inducing foam formation using the Lagrangian particle tracking velocimetry utilizing the Shake-The-Box algorithm. With the systems equipped with four high-speed cameras, time-series of images of fluid tracer particles were acquired. The Vortex-In-Sharp (VIC#) method was used to reconstruct the Eulerian flow fields of the particle tracks. The impinging jet was characterized as plume-like along the vertical direction with two distinct layers: developing shear and fully developed shear. The streamwise vortex structures of the continuous phase were influenced by the bubble plume motion, and the results showed high amplitude oscillations of the acceleration and deceleration near the jet source resulting in the formation of ring-like vortices, which break down as the jet moves downstream with its momentum dissipated. The flow of the continuous phase of impinging jet was self-similar both at the developed shear layer and the fully developed diffusion layer beneath the water pool and is characterized as homogeneous shear flow with anisotropy turbulence. The classical assumption of self-similarity with Gaussian profiles for continuous phase velocity is verified experimentally. We found that the results show a huge potential of blue energy harvesting from the low frequency (∼2 Hz) dissipating kinetic energy of the turbulent plume-like jet underneath the impinging water surface using triboelectric nanogenerator.

A novel semi-analytical approach based on scaled boundary finite element method for fluid-structure coupling analysis of liquid sloshing in 3D containers

In this paper, a novel semi-analytical approach is proposed for the three-dimensional fluid-structure coupling analysis of liquid sloshing in elastic containers subjected to harmonic and seismic loading in the horizontal direction, based on the scaled boundary finite element method (SBFEM). A modified SBFEM model, referred to as the scaling surface-based SBFEM, is developed to simulate the container wall, which is treated as a thin shell structure. Within the framework of the scaling surface-based SBFEM, the geometry of the shell structure is entirely determined by scaling one surface of the structure. This approach differs significantly from the standard SBFEM, where approximation is achieved through coordinate mapping based on a scaling center, thereby enhancing the modeling accuracy and efficiency. Hydrodynamic pressure is treated as an independent nodal variables in the governing equations of the fluid domain, which is modeled using the standard scaling centre-based SBFEM. The coupled fluid-structure system is assembled by applying equilibrium and compatibility boundary conditions to ensure the balance of interaction forces. A synchronous solution algorithm, combined with the implicit-implicit scheme of the Newmark method, is used to determine the dynamic responses of the coupled system. The main advantage of this novel approach is that it meshes and discretizes the boundaries instead of the entire structural and fluid domains, thereby reducing computational costs. Additionally, analytical solutions can be obtained along the radial direction of the interior domain, enhancing the accuracy and convergence of the results. Another advantage is the approach's ability to provide a unified modeling framework for structures of any shape. Furthermore, the asymmetry issue of the coefficient matrix can be effectively avoided by using a synchronous solution algorithm. Benchmark examinations confirm the superior computational accuracy and robustness of the proposed approach. A comprehensive parametric study is conducted, focusing on the effects of liquid filling levels, as well as geometric and material parameters, on the transient vibration and distribution behaviors of the fluid-structure coupling system.

Stability of 2D inviscid MHD equations with only fractional magnetic diffusion in the horizontal direction

Stability of 2D inviscid MHD equations with only fractional magnetic diffusion in the horizontal direction

Exploring mechanical properties and cracking behavior of AC-13 and OGFC-16 aggregate-segregated asphalt mixtures

Aggregate segregation compromises the homogeneity of asphalt pavement, which diminishes the road performance of the asphalt mixture. The segregation behavior and damage mechanism of asphalt mixture are complex. To investigate the mechanical properties and cracking behavior of asphalt mixtures with varying degrees of aggregate segregation, the dense-graded asphalt mixture with the nominal maximum size of 13.2mm (AC-13) and Open Graded Friction Course with the nominal maximum size of 16.0mm (OGFC-16) with varying degrees of segregation were designed. Indirect tensile test and the digital image correlation (DIC) technology was employed to analyze the strain distribution and strain evolution at the crack initiation point within the asphalt mixtures. The parameters were also proposed to evaluate the resistance to cracking for the segregated asphalt mixtures at a mesoscopic scale. The results show that increased segregation of coarse aggregates in AC-13 mixtures leads to decreased indirect tensile strength, lower maximum tensile strain along the horizontal direction (E11), and reduced failure displacement. Conversely, segregation of fine aggregates in OGFC-16 mixtures results in increased tensile strength, maximum strain, and failure displacement. Higher amount of coarse aggregates in the asphalt mixture contributes to a more intricate strain distribution and a greater number of strain peaks. Dense-graded mixtures show larger strain concentration zones prior to cracking, while smaller stress concentration zones are observed in open-graded mixtures. The horizontal strain-time curve displays distinct stages of stable growth, rapid growth, and rapid decline. Aggregate segregation results in more intricate crack patterns with larger inclination angles, influenced by the random distribution and shapes of coarse aggregates. Novel indexes such as strain uniformity (P1,2) and strain density during crack development (DW) effectively evaluate mesoscopic cracking resistance of asphalt mixtures. The results offer valuable insights into cracking behavior and improve evaluation methods for the mechanical performance of aggregate-segregated asphalt mixtures.

Evaluation of Lower Limb Angular Acceleration in Healthy and Hallux Valgus Young and Older Women During Gait

Objectives: To comprehend the kinematic effects of hallux valgus (HV) deformity on young and older people, we assessed the angular acceleration of the joints in the lower limbs of these women. Methods: Forty-eight women in two groups, young adults (20-30 years old) and older adults (50-60 years old), participated in this study (12 healthy and 12 with HV). We used an inertial measurement unit (IMU)-based motion capture system to measure the kinematics of motion. Biomechanical variables were assessed at an ideal speed during gait (stance and swing phases). All modules were calibrated in advance and then attached to the right thigh, shank, and foot. Results: The results showed that in the young group, angular acceleration was significantly different during gait in all planes of the ankle joint, the sagittal plane of the knee joint, and the horizontal and frontal planes of the hip joint. In the older group, it was significantly different in the sagittal plane of the ankle and knee and the sagittal and frontal planes of the hip joint. Discussion: It appears that the angular acceleration of the lower limb joints was affected by HV, especially in the young group. Additionally, the angular acceleration of the knee joint was less affected in both groups.

Crack evolution mechanism of stratified rock mass under different strength ratios and soft layer thickness: Insights from DEM modeling

Research on stratified rock masses, which are common geological formations, has primarily focused on their mechanical properties, while studies on crack evolution and microscopic damage mechanisms remain limited. This study addresses this gap by investigating the combined effects of strength ratios and soft layer thicknesses on the microcrack evolution mechanism of stratified rocks using the discrete element method (DEM). Through FISH language programming in the particle flow code (PFC), this study reveals the acoustic emission (AE) characteristics, crack initiation and propagation, damage degree, and final failure characteristics. The key findings are: (1) Higher strength ratios between the hard and soft components of stratified rocks make specimens more sensitive to increases in soft layer thickness. (2) Three types of AE events were identified: continuous active, intermittent active, and silent. (3) Cracks initiate at the interface between components and propagate along the interface into the rock matrix. The strength ratios determine the crack propagation path and the damage extent of the components. (4) The failure of stratified rocks is primarily controlled by the soft component. Crack connections typically form vertical and sub-vertical tensile failure planes in the hard component, and a shear failure surface with a “V”-shaped intersection in the soft component.

Muscle twitch thresholds depending on the direction of current stimulation

Abstract Acoustic or visual warning signals for workers in hazardous situations might fail under loud and/or lowvisibility work situations. A warning system that uses electrocutaneous stimulation can overcome this problem. This study aimed to compare vertical, diagonal, and horizontal current stimulation directions at the upper arm to select the one with the lowest amount of muscle twitching. Fourteen electrodes were attached in two rows to the upper right arm of 15 participants. The stimulation was conducted with bi-phasic rectangular pulses of 150 μs and amplitudes of up to 25 mA. Muscle twitch thresholds have been determined and a circumferential stimulation signal was presented as warning pattern for the three current stimulation directions and evaluated regarding alertness, discomfort, and urgency. For single stimulation pulses, muscle twitches occurred slightly less often at the horizontal stimulation direction compared to the other two and muscle twitch thresholds showed no systematic differences. For the warning patterns, no considerable differences were found regarding the evaluation of alertness, discomfort, and urgency and no differences were found for muscle twitching. In conclusion, all orientations seem suitable for warning pattern presentation and none of the directions has a clear advantage in reducing muscle twitch.

Technical study of blasting geometry to reduce the level of fragmentation at the Air Laya mine site pt. Bukit Asam, Tbk.

Abstract Research was conducted at the PT. Bukit Asam Air Laya Mine Site. The aim of the blasting activity is to explode the B2-C interburden layer in order to obtain Seam C coal. The drilling pattern used is a staggered pattern with a vertical drilling direction. The actual blasting geometry used is with a burden of 7 m, spacing of 8 m, hole depth of 8 m, stemming of 4 m, and powder column of 4 m. The level of blasting fragmentation for sizes greater than 160 cm based on theoretical calculations is 26.49 %, while the target set by the company for boulder fragmentation is no more than 20%. To reduce the level of fragmentation, changes were made to the actual geometry by conducting studies using the RL Ash, CJ Konya, and ICI Explosive theories. From this study, recommendations for the proposed blasting geometry were obtained with a burden of 6 m, spacing of 9 m, hole depth of 11.66 m, stemming of 5.14 m, and powder column of 6.52 m. With these changes in geometry, fragmentation measuring more than 160 cm was obtained at 17.15%, or it can be said to achieve the fragmentation target of less than 20%.

Brightness improvement of edge-emitting lasers by combining vertical broad-area HiBBEE and laterally inhomogeneous waveguides

1060 nm high-brightness vertical broad-area edge-emitting (HiBBEE) lasers with laterally inhomogeneous ridge waveguides are investigated. The effects of triangular, fishbone, and square-shaped corrugations on the loss of fundamental and higher-order modes are calculated by the beam propagation method. Lasers with 15 µm ridge width, 2 mm cavity length, and various types of corrugations are fabricated. The combination of vertical broad-area and fishbone- and square-shaped corrugations yields excellent beam quality, with beam quality factors M2 ≤ 1.5 and 2.6 in vertical and lateral directions, respectively. Despite the loss in output power due to the increased losses incurred by the corrugations, corrugated lasers provide higher brightness than the reference laser with a conventional straight ridge waveguide. HiBBEE lasers with square-shaped corrugated ridges provide 1.7 times larger brightness than the reference lasers.

A transcrestal sinus floor elevation strategy based on a haptic robot system: An in vitro study.

To reveal the force profiles recorded by haptic autonomous robotic force feedback during the transcrestal sinus floor elevation (TSFE) process, providing a reference for the surgery strategy during TSFE. A total of 42 maxillary sinus models with different angles of the sinus floor (30°, 40°, 50°, 60°, 70°, 80°, and 90°, compared to vertical plane) were 3D printed. Implant site preparation was performed using a robotic system, and the total force (Ft) and axial force along the drill (Fz) during the surgery were recorded by the haptic robotic arm. The actual initial breakthrough point (drill contacting sinus floor) and complete breakthrough point (drill penetrating the sinus floor) were defined visually (the actual IBP and the actual CBP). The theoretical initial breakthrough point (the theoretical IBP) and the theoretical complete breakthrough point (the theoretical CBP) defined by the robot-guided system and the CBCT were determined by real-time force feedback and imaging distance measurement, respectively. The distance from the bottom of the resin model to the actual IBP and the actual CBP was defined as Di and Dt, respectively. The difference in Fz began to increase significantly at 70°, while the difference in Ft became significant at 60°. When the angle was greater than 70°, there was no significant difference in the discrepancy between the actual and theoretical perforation points. Compared to judging the breakthrough point by CBCT, real-time force feedback TSFE under robotic surgery achieved more accurate initial breakthrough point detection. The smaller the angle, the larger the breakthrough force for the drill. The real-time force feedback of haptic robotic system during TSFE could provide reliable reference for dentists. More clinical studies are needed to further validate the application of robotic surgery assisted TSFE.

Rheology of polyacrylamide-based fluids and its impact on proppant transport in hydraulic fractures

Rheological experiments and measurements of particle settling velocity under static conditions were conducted for two types of polyacrylamide (PAA-based) fluids. The flow behavior of the viscoelastic fluids is described by a simplified, three-parameter model that integrates a constant viscosity at low shear rates with a power-law viscosity dependency at higher shear rates. The estimated dependencies of the rheological parameters and particle settling velocity on PAA concentration align with the classical power-law scaling for semi-dilute polymer solutions. The identified scaling offers valuable insight for optimizing the chemical composition of fracturing fluids, thereby improving the efficiency of hydraulic fracturing technology. By applying the lubrication approximation to the Navier–Stokes equations, a set of equations for the suspension flow in a vertical plane channel, characterized by the three-parameter rheology model, was derived. In typical fracturing conditions, the conventional power-law viscosity model used in current fracturing simulators significantly overestimates the gap-averaged apparent fluid viscosity compared to the proposed model. The novel model of the suspension flow aims to enhance the accuracy of proppant transport models applied in hydraulic fracturing simulators. Based on the three-parameter rheology model, a new model of particle settling in the studied PAA-based fluids is developed. It is based on smart Stokes' law, where viscosity is calculated according to either the plateau or power-law region, depending on the self-induced shear rate. The new model more accurately approximates experimentally determined settling velocity of proppant under static conditions across a broad range of PAA concentrations than existing models.

Structural Design of the Multifunctional Sports Hall in the City of Blaj, Romania

Abstract The multifunctional sports hall presented in the paper is of a dual-mixed type, combining spatial frames with reinforced concrete diaphragms and a steel roof frame. The spans of the roof girder are very large, 53.80 m. They were designed as spatial structures made of two lattice beams, braced between the upper and the lower chords, plus a set of counterbraces in the transvers vertical plane. As the sports hall was built in a seismic area of the country, a system of seismic protection needed to be adopted. The paper presents the architectural, technical and functional solution of the Sports Hall, explaining in detail the solution adopted for the seismic isolation of the building.