Surface Motion Research Articles

Research on Strip Coal Pillar Technology under the Construction Group of Gangue Filling and Recycling

In order to reduce the various impacts of surface movement caused by coal mining on the human living environment, avoid the accumulation of coal gangue on the surface, and recover the strip coal pillar resources left under urban areas, based on the stability of the binary bearing structure composed of backfilled gangue and narrow coal pillars after strip mining and the characteristics of the equivalent mining height model, theoretical analysis and numerical simulation methods were comprehensively used to analyze the factors affecting the stability of coal pillars, the ultimate strength of coal pillars, and the safety factor of coal pillar stress under the condition of binary bearing structure. Through comparative analysis of deformation of surrounding rock after strip mining and coal pillar recovery, it was found that the mining pressure manifestation of strip coal pillar gangue filling is weak, without obvious initial and periodic pressure phenomena, and the top control is relatively easy without the risk of dynamic pressure. The research results provide useful reference and guidance for the first application of fully mechanized mining technology in urban strip coal pillar recovery in coal mines.

Object oriented data analysis of surface motion time series in peatland landscapes

Abstract Peatlands account for 10% of UK land area, 80% of which are degraded to some degree, emitting carbon at a similar magnitude to oil refineries or landfill sites. A lack of tools for rapid and reliable assessment of peatland condition has limited monitoring of vast areas of peatland and prevented targeting areas urgently needing action to halt further degradation. Measured using interferometric synthetic aperture radar (InSAR), peatland surface motion is highly indicative of peatland condition, largely driven by the eco-hydrological change in the peatland causing swelling and shrinking of the peat substrate. The computational intensity of recent methods using InSAR time series to capture the annual functional structure of peatland surface motion becomes increasingly challenging as the sample size increases. Instead, we utilize the behaviour of the entire peatland surface motion time series using object oriented data analysis to assess peatland condition. Bayesian cluster analysis based on the functional structure of the surface motion time series finds areas indicative of soft/wet peatlands, drier/shrubby peatlands, and thin/modified peatlands. The posterior distribution of the assigned peatland types enables the scale of peatland degradation to be assessed, which will guide future cost-effective decisions for peatland restoration.

Three-Dimensional Surface Motion Displacement Estimation of the Muz Taw Glacier, Sawir Mountains

Research on glacier movement is helpful for comprehensively understanding the laws behind this movement and can also provide a scientific basis for glacier change and analyses of the dynamic mechanisms driving atmospheric circulation and glacier evolution. Sentinel-1 series data were used in this study to retrieve the three-dimensional (3D) surface motion displacement of the Muz Taw glacier from 22 August 2017, to 17 August 2018. The inversion method of the 3D surface motion displacement of glaciers has been verified by the field measurement data from Urumqi Glacier No. 1. The effects of topographic factors, glacier thickness, and climate factors on the 3D surface displacement of the Muz Taw glacier are discussed in this paper. The results show that, during the study period, the total 3D displacement of the Muz Taw glacier was between 0.52 and 13.19 m, the eastward displacement was 4.27 m, the northward displacement was 4.07 m, and the horizontal displacement was 5.90 m. Areas of high displacement were mainly distributed in the main glacier at altitudes of 3300–3350 and 3450–3600 m. There were significant differences in the total 3D displacement of the Muz Taw glacier in each season. The displacement was larger in summer, followed by spring, and it was similar in autumn and winter. The total 3D displacement during the whole study period and in spring, summer, and autumn fluctuated greatly along the glacier centerline, while the change in winter was relatively gentle. Various factors such as topography, glacier thickness, and climate had different influences on the surface motion displacement of the Muz Taw glacier.

Study on the Stability Evolution Mechanism of a Red Mud Dam During Construction and Safety Under Earthquake During Operation

Instability in red mud dam bodies is not uncommon. In order to study the stability evolution mechanism during the process of red mud landfill and the deformation characteristics under earthquake action when the landfill site is closed, the deformation law and potential sliding surface motion characteristics of the landfill site were explored based on the finite difference method, revealing the influence of peak ground acceleration (PGA) on red mud deformation. The results showed that: (1) As the height of the red mud landfill increases, the shear force of the red mud landfill gradually increases. Meanwhile, the maximum shear force always occurs near the initial dam, indicating that under the action of gravity, the possibility of shear slip occurring near the initial dam is the highest. (2) The distribution pattern of the plastic zone in the red mud pile during the filling process is relatively complex, and continuous monitoring of the filling process should be carried out to ensure the safety of the filling project. (3) With the increase in earthquake acceleration, the shear force of red mud piles gradually increases. Meanwhile, as the acceleration increases, the maximum shear stress always occurs at the bottom of the initial dam body. Under the action of power, special attention should be paid to the stability of the pile near the initial dam.

Numerical Study of the Water Surface Movement on the Breaching Process of Natural Dams

Numerical Study of the Water Surface Movement on the Breaching Process of Natural Dams

Cavitation dynamics in creeping flow

We investigate the heterogeneous cavitation phenomenon in water when a spherical surface is abruptly separated from a nearby flat substrate, at a distance of approximately 10 nm. By tracking the surface separation using Newton ring positions, and capturing the bubble evolution with a high-speed camera on a microscope, we compare our experimental findings with hydrodynamic predictions at low Reynolds numbers. Upon upward movement of the spherical surface, the resulting bubble develops branched fingers through the Saffman–Taylor instability. Simultaneously, negative liquid pressures in the range $\sim$ 10 atm are observed. These large tension values occasionally lead to secondary nucleation events. The bubble sizes satisfy a predicted Family–Vicsek scaling law where the bubble area is proportional to the inverse bubble lifetime. The fact that creeping flow cavitation bubbles are more short-lived the larger they are separates them from bubbles that are governed by inertial dynamics.

Pore-Scale Visualized Transport and Retention of Fibrous and Fragmental Microplastics in Porous Media under Various Surfactant Conditions.

For advancing current knowledge on the transport of microplastics (MPs) in the environment, this study used a real-time pore-scale visualization and quantitative system to examine the motions and mobility of fibrous and fragmental MPs under various surfactant (AEO, CTAC, and AES) and electrolyte conditions. The videos showed that fibrous MPs formed tangles through entanglement, which moved in an axial direction aligned with the flow streamline. Both fibrous and fragmental MPs showed suspended movement as well as surface movement (e.g., sliding, rolling, and saltating) in the porous media. Some deposited fibrous MPs showed flexible deformation due to shear flow. Compared to fragmental MPs, fibrous MPs showed lower mobility due to the tendency to deposit and clog the porous media. The mobility of fragmental MPs was enhanced in the presence of AEO but remained relatively unchanged with AES. In the presence of CTAC, the mobility of fragmental MPs was slightly inhibited under low ionic strength (IS) conditions but remarkably enhanced under high IS conditions. However, the mobility of fibrous MPs was largely unaffected by the surfactants. Both the numerical model and FDLVO calculations effectively described the transport and deposition of MPs in porous media.

A partitioned functional-decomposition scheme for modelling wave-ship-sloshing interaction

A novel partitioned function decomposition method is proposed and validated for accurately and effectively solving the interaction between waves and ships with sloshing effect. This scheme employs a hybrid functional-decomposition method that utilizes both potential and viscous flows to accurately and efficiently solve the wave-ship interaction in the external domain, while employing the original viscous method for simulating sloshing in the internal domain. To further enhance computational efficiency, a single-phase Level-set method is employed. Firstly, the issue of non-conservation in the level-set model is addressed through the application of a mass correction method. Additionally, based on the principle of mass conservation, modifications are made to the boundary conditions for free surface motion. As a result, an improved single-phase Level-set method is developed, which combines jump condition correction and mass correction. Through simulations involving linear and nonlinear free surfaces, impulsive pressures, overall forces on the tank, as well as comparisons with experimental data, it is observed that the proposed Level-set method effectively solves the sloshing in the internal domain, a problem for which the traditional single-phase Level-set method often fails to tackle with. Subsequently, by adopting a multi-block grid technique to mark tank and non-tank grid blocks and integrating the improved single-phase Level-set method with the SWENSE model, a partitioned function decomposition method is established to handle ship motions with sloshing effect in waves. It is found that simultaneously solving the internal and external flow problems using traditional implicit and explicit motion-solving methods poses certain challenges. Therefore, an implicit-inner-iteration solution method is proposed. By combining the proposed motion-solving method with the partitioned function decomposition model, satisfactory results are achieved for the wave-ship-sloshing interaction.

Multi-level digital-twin models of pulmonary mechanics: correlation analysis of 3D CT lung volume and 2D Chest motion

Creating multi-level digital-twin models for mechanical ventilation requires a detailed estimation of regional lung volume. An accurate generic map between 2D chest surface motion and 3D regional lung volume could provide improved regionalisation and clinically acceptable estimates localising lung damage. This work investigates the relationship between CT lung volumes and the forced vital capacity (FVC) a surrogate of tidal volume proven linked to 2D chest motion. In particular, a convolutional neural network (CNN) with U-Net architecture is employed to build a lung segmentation model using a benchmark CT scan dataset. An automated thresholding method is proposed for image morphology analysis to improve model performance. Finally, the trained model is applied to an independent CT dataset with FVC measurements for correlation analysis of CT lung volume projection to lung recruitment capacity. Model training results show a clear improvement of lung segmentation performance with the proposed automated thresholding method compared to a typically suggested fixed value selection, achieving accuracy greater than 95% for both training and independent validation sets. The correlation analysis for 160 patients shows a good correlation ofRsquared value of 0.73 between the proposed 2D volume projection and the FVC value, which indicates a larger and denser projection of lung volume relative to a greater FVC value and lung recruitable capacity. The overall results thus validate the potential of using non-contact, non-invasive 2D measures to enable regionalising lung mechanics models to equivalent 3D models with a generic map based on the good correlation. The clinical impact of improved lung mechanics digital twins due to regionalising the lung mechanics and volume to specific lung regions could be very high in managing mechanical ventilation and diagnosing or locating lung injury or dysfunction based on regular monitoring instead of intermittent and invasive lung imaging modalities.

Subsidence and Uplift in Active and Closed Lignite Mines: Impacts of Energy Transition and Climate Change

This study examines the combined effects of decommissioning lignite mining operations and long-term climate trends on groundwater systems and land surface movements in the Konin region of Poland, which is characterised by extensive open-pit lignite extraction. The findings reveal subsidence rates ranging from −26 to 14 mm per year within mining zones, while land uplift of a few millimetres per year occurred in closed mining areas between 2015 and 2022. Groundwater levels in shallow Quaternary and deeper Paleogene–Neogene aquifers have declined significantly, with drops of up to 26 m observed near active mining, particularly between 2009 and 2019. A smaller groundwater decline of around a few metres was observed outside areas influenced by mining. Meteorological data show an average annual temperature of 8.9 °C from 1991 to 2023, with a clear warming trend of 0.0050 °C per year since 2009. Although precipitation patterns show a slight increase from 512 mm to 520 mm, a shift towards drier conditions has emerged since 2009, characterised by more frequent dry spells. These climatic trends, combined with mining activities, highlight the need for adaptive groundwater management strategies. Future research should focus on enhanced monitoring of groundwater recovery and sustainable practices in post-mining landscapes.

Surface instability driven by wetting-drying cycles hinders the colonization by biocrusts in Tabernas Desert

AbstractCatchment asymmetry in the Tabernas Desert suggests a relatively greater instability in the sunnier hillslope in a very early stage of catchment development due to abiotic factors, which would hinder the biocrust colonization. In the absence of erosion, such a difference in stability between opposite hillslopes could be due to differences in wetting-drying cycles. To verify this, as biocrust types assumed as successional stages are associated with different microhabitats, the surface movements of three types of physical crusts (Structural, Depositional and Island) and four biocrust types, representative of different stages of succession (Incipient, Cyanobacteria, Squamarina and Lepraria), were analyzed based on the distances calculated between markers placed on a grid on the soil surface. Two sample groups were analyzed: in situ samples, with four plots per crust type, and ex situ, with four unaltered samples per crust type extracted from the field site to control the effect of slope angle, orientation, trampling by animals, etc. Physical crusts showed greater surface instability compared to biocrusts, and this instability was influenced by the amount and frequency of precipitation. Biocrusts were more stable and elastic to surface movements, often recovering their initial position, and this stability increased throughout succession. Furthermore, the results showed that reducing instability (when sediment deposition ceases) favors colonization. Our results support the hypothesis that, in absence of erosive events, larger surface instability due to wetting-drying cycles hinders biocrust colonization on the relatively sunnier hillslopes with physical crusts; however, it is unknown where (or when) biocrust can develop.

STEWART PLATFORM MULTIDIMENSIONAL TRACKING CONTROL SYSTEM SYNTHESIS

Context. Creating guaranteed competitive motion control systems for complex multidimensional moving objects, including unstable ones, that operate under random controlled and uncontrolled disturbing factors, with minimal design costs, is one of the main requirements for achieving success in this class devices market. Additionally, to meet modern demands for the accuracy of motion control processes along a specified or programmed trajectory, it is essential to synthesize an optimal control system based on experimental data obtained under conditions closely approximating the real operating mode of the test object. Objective. The research presented in this article aims to synthesize an optimal tracking control system for the Stewart platform’s working surface motion, taking into account its multidimensional dynamic model. Method. The article employs a method of a multidimensional tracking control system structural transformation into an equivalent stabilization system for the motion of a multidimensional control object. It also utilizes an algorithm for synthesizing optimal stabilization systems for dynamic objects, whether stable or not, under stationary random external disturbances. The justified algorithm for synthesizing optimal stochastic stabilization systems is constructed using operations such as addition and multiplication of polynomial and fractional-rational matrices, Wiener factorization, Wiener separation of fractional-rational matrices, and the calculation of dispersion integrals. Results. As a result of the conducted research, the problem of defining the concept of analytical design for a Stewart platform’s optimal motion control system has been formalized. The results include the derived transformation equations from the tracking control system to the equivalent stabilization system of the Stewart platform’s working surface motion. Furthermore, the structure and parameters of the main controller transfer function matrix for of this control system have been determined. Conclusions. The justified use of the analytical design concept for the Stewart platform’s working surface optimal motion control system formalizes and significantly simplifies the solution to the problem of synthesizing complex dynamic systems, applying the developed technology presented in [1]. The obtained structure and parameters of the Stewart platform’s working surface motion control system main controller, which is divided into three components W1, W2, and W3, improve the tracking quality of the program signal vector, account for the cross-connections within the Stewart platform, and increase the accuracy of executing the specified trajectory by increasing the degrees of freedom in choosing the controller structure

Effects of Kitchen Cooking Height on Upper Limb Muscle Activation, Posture, and Perceived Discomfort of Chinese Older and Young Women.

Inappropriate kitchen cooking height may lead to uncomfortable and muscle fatigue. This study aims to compare the effects of kitchen cooking height on upper limb muscle activation, posture, and perceived discomfort among different age groups. Fifteen older women and fifteen young Chinese women each completed three consecutive 20 s simulated cooking tasks at five different heights. Surface electromyography, motion capture, and Borg CR10 scale were used to measure muscle loading. Results showed that the main power muscles of the cooking task were the anterior deltoid, brachioradialis, and biceps brachii. The higher muscle contribution rate of biceps brachii and triceps brachii was found in the younger group compared to the older group (p < 0.05). Muscle activation of the anterior deltoid (different in 1.28-2.87%), pectoralis major (different in 1.43-1.69%), and erector spinae (different in 0.6-1.21%), as well as right shoulder abduction (different in 5.91°-7.96°), were significantly higher in older group than in young group (p < 0.05). Muscle activation of the anterior deltoid and right shoulder abduction decreased significantly with decreasing height (p < 0.05). A height of 200-250 mm below the elbow was considered a more comfortable cooking height for both age groups. This provides data to support the design of cabinet sizes.

Aeroelastic Effects in Supersonic Shock-Turbulent Boundary Layer Interaction over Flexible Panels

The dynamic coupling between a Mach 1.94 shock wave/turbulent boundary layer interaction (SBLI) and a flexible panel is investigated. High-order numerical simulations are performed for distinctly different dynamic panel motions and rigid snapshots of their maximum deflected shape. They are compared with a baseline interaction over a rigid planar wall. The panel’s dynamic surface motions were obtained from the Air Force Research Laboratory (AFRL) wind tunnel experiments. The primary aim of the study was to determine whether there were any differences in the flow pressure loading on the compliant panel due to the various rigid and dynamic deformations considered. The results show that the examined panel deformations increase the SBLI size near the panel midpoint, where the deformation amplitude tends to be the largest. Relative to the rigid planar case, the examined surface deformations cause the mean-flow high-pressure surface loading caused by the impinging shock wave to shift downstream along the compliant panel midspan, albeit by a small amount. The spectrogram of the dynamic deformation and the flow surface pressure response suggests that the two are strongly coupled at the dominant (primary) mode but less so at the secondary modes. Although the primary mode frequencies overlap, they do not exactly match, with the pressure response frequency always being slightly higher in all three cases. The rigid deformations did not enhance the pressure power content at the SBLI. However, pre-SBLI and near the panel leading edge, the pressure power spectrum weakly increased throughout the resolved frequency range and overlapped with the onset of the amplification found in the dynamic deformation cases. Post-SBLI, the rigid deformations cause a weak enhancement at frequencies below 1 kHz, which closely match the dominant and secondary pressure response frequencies obtained in the dynamic cases.

Dynamic visualization study of in situ cleaning of polystyrene microparticles off silicon wafer surface

With the improvement of chip performance, the requirements for cleaning the surface of silicon wafers are becoming higher. However, due to equipment and technology, it is difficult to observe the complex motion processes of particles at the microscopic scale. In this paper, an in situ dynamic visualization experiment on the cleaning of Polystyrene Latex (PSL) on the surface of silicon wafers is carried out by using a high-speed camera and image processing software. The mechanical behavior of PSL particles in fluid was investigated on a microscopic scale, and the trajectory and force of the polystyrene particles on the surface of the wafers were visualized, which provided a new perspective for understanding the complex cleaning process. Theoretical models were developed to explain the motion characteristics of the particles by calculating parameters such as van der Waals force, surface tension, and trailing force, and these models provide a theoretical basis for optimizing the cleaning process. There are four particle motion modes in the fluid: (1) interface capture, where the particles on the surface of silicon wafer are trapped by gas–liquid interface under surface tension; (2) particle collision, where the particles captured by the water film collide with the particles on the wafer surface to make the latter leave the silicon wafer; (3) jump attachment, where the particles jump and attach to the surface of the particle group under the action of lift; and (4) wall surface movement, where the particles start up under the action of water flow and then leave the silicon wafer quickly.

High-Speed Three-Dimensional-Digital Image Correlation and Schlieren Imaging Integrated With Shock Tube Loading for Investigating Dynamic Response of Human Tympanic Membrane Exposed to Blasts.

Investigating the dynamic response of human tympanic membranes (TMs) exposed to blasts requires full-field-of-view and three-dimensional (3D) methodologies. Our paper introduces a system that combines high-speed 3D digital image correlation (HS 3D-DIC) and Schlieren imaging (HS-SI) with a custom-designed shock tube for generating blast waves. This integrated system allows us to measure TM surface motions under intense transient loading, capturing full-field-of-view shape deformations exceeding 100 μm with a temporal resolution of 10 μs. System characterization encompasses (i) measuring the shock tube's output levels and repeatability, (ii) assessment of the spatial and temporal resolutions of the imaging techniques, and (iii) identification of overall system limitations. Optimizing these factors is crucial for improving the reliability of our system to ensure the accurate measurement of deformations. To assess our shock tube's reliability in generating repeated blast waves, we instrumented it with high-pressure (HP) and high-frequency (HF) pressure sensors along the blast wave pathway to record overpressure waveforms and compared them with Schlieren imaging visualized blast waves. We validate our HS 3D-DIC measured deformations by comparing them with deformations measured using single-point laser Doppler vibrometry (LDV), establishing a comprehensive assessment of the TM's dynamic response and potential fracture mechanics under blast. Finally, we test our approach with 3D-printed TM-like samples and a real cadaveric human TM. This methodology lays the groundwork for further investigations of blast-related auditory damage and the invention of more effective protective and medical solutions.

Machine Learning-Based Prediction of Aircraft Taxi-In Time: A Case Study at Beijing Capital International Airport

Accurate prediction of flight taxi-in time has a significant meaning in allocating aircraft support resources reasonably and improving airport surface movement efficiency. It can effectively overcome the deficiency of extensive aircraft arrival time prediction in major airports currently. Taking Beijing Capital International Airport as the research object, we analyzed the influence factors of taxi-in time and constructed the feature set; Then we applied linear regression, K-nearest neighbor, support vector regression, decision tree, random forest and gradient boosting regression tree, which were widely used in the prediction of taxi-out time, to predict the taxi-in time. The results show that the prediction accuracy of the six machine learning models is over 90%within \pm3minutes, it means that the construction of feature set and the selection of models are effective; The gradient boosting regression tree model has the best performance based on the prediction results and model fitting evaluation results; The surface traffic flow features have the largest contribution to the prediction model, and the newly introduced cross-regional feature has more contribution to the prediction model than most traditional features, according to the prediction results of gradient boosting regression tree.

Aircraft Surface Movement and Operation Monitoring Systems in General Aviation and Commercial Airports: A State-of-the-Art Review

Aircraft Surface Movement and Operation Monitoring Systems in General Aviation and Commercial Airports: A State-of-the-Art Review

Numerical simulation of the movement of the water surface with macroscopic particles during a partial dam break for various complex reliefs

In this paper, it was considered a numerical simulation of the water surface movement during the partial collapse of the destruction of a dam with complex terrain. The numerical simulations took into account debris after a partial collapse of the dam, which imitates debris and moves downstream with the water flow. Carrying out these calculations brings the results closer to the real scenario. The mathematical model was based on the Navier–Stokes equations and uses the turbulent large eddy method (LES) model describing the flow of an incompressible viscous fluid. To describe the movement of a two-phase fluid, the volume of fluid (VOF) methods for the phase were used, and the Discrete Phase Model (DPM) and Macroscopic Particle Model (MPM) were used to describe the movement of particles. For the numerical solution of this system of equations, the Pressure Implicit Split Operator (PISO) numerical algorithm was chosen. The results show that the model is accurate and capable of handling very complex interactions such as particle transport or hydrodynamic actions on structures if the appropriate scales are reproduced. Also in this work, a three-dimensional (3D) model of the flow of a dam break on uneven terrain was considered and combined problems were performed that are closer to real conditions. For combined problems, flood zones and flood times were determined, knowledge of which will help evacuate people from dangerous areas. The accuracy of the 3D model and the selected numerical algorithm were verified using two natural measurements.

CATALOG OF LANDSLIDES OF THE CITY OF ZENICE WITH SPECIFIC CAUSES

As part of its activities, the Federal Institute of Geology carries out mapping of active landslides in the territory of the Federation of Bosnia and Herzegovina, and my task is to map instability in the area of the City of Zenica. A very large number of landslides were registered during the catastrophic rainfall that occurred in 2014. Following these phenomena and certain records, detailed mapping of unstable slopes and records of unstable surfaces was started. The cadastre is defined in such a way that it displays all input data with location polygons in GIS. Not in the field, quite recognizable causes were observed, which are always a combination of bad geological and hydrogeological conditions with a significant anthropogenic factor. The slope of the terrain is also very unfavourable, and gravity also played a significant role in the instability of these slopes. Almost all registered landslides have unregulated water (surface, underground, waste). The frequent occurrence of earthquakes on this section also significantly threatened the stability of slopes and buildings, and on the spot, the consequences of cracking and shearing of buildings were evident as a result of the earthquake. A special review will be given to the activation of mudflows during extensive rainfall in this area, which is not rare. A significant share in the formation of mudflows belongs to heavy precipitation, which over time formed the so-called "watersheds" where water was transported from higher to lower parts of the slope. However, during the climate changes, there was a significant increase in the amount and frequency of precipitation, which carried the surface cover and rock blocks that were moved down the steep slopes. Road approaches to the villages, as well as a significant number of buildings, made artificial dams and cut cuts that were a natural way of draining water. So you have a significant number of buildings built exactly on these "watersheds" that represent the dam. In the newly created situation, by changing the natural paths of movement of surface and underground water, it would be necessary to regulate the water below and around the road strip, as well as the drainage of water around buildings. Only after the water has been drained, certain geotechnical procedures can be carried out to stabilize the slope and to permanently rehabilitate it, so that the inhabitants of these villages do not constantly fear during rainfall.