Displacement Analysis Research Articles

Combination of free network adjustment with S- transformation and Kalman filter with original data information adjustment for displacement analysis

To evaluate the displacement of the coordinates of the GNSS network points according to the measured data of the periods, the theory of free network adjustment has been widely applied. However, changing the stable points in the cycles if only considering the coordinate difference after the adjustment in the normal way will not be accurate because the result of the free network adjustment of the coordinates is determined with different origin points. Therefore, it is necessary to convert the coordinate system of the previous period to the coordinate system of the following period, applying S - transformation to analyze the deformation. In addition to the displacement of the points, it is necessary to define the velocity and acceleration parameters of the displacement. In this paper, a method of displacement analysis has been studied based on using GNSS network measurement data in measurement cycles and applying the theory of free network adjustment and S transformation, Kalman filtering technique and rationalizing the geodetic network adjustment theory with the error information of the original data to analyze and predict the displacement on the experimental area of the Saigon River area. The analysis concludes the shift based on the student distribution (t - distribution). In the study, static and dynamic models were considered and gave consistent calculation results. The theory has been proven to develop the Kalman filter technique for deformation analysis and prediction problems by applying GNSS technology. This result allows to expand the scope of application of GNSS technology for monitoring and analysis of landslides, subsidence and displacement of the Earth's crust on a local scale as well as a territorial extent in Vietnam, and can e data from GNSS CORS observation stations.

Methods for the Future, Futures for Methods: Collaborating with Syrian Refugee Youth in Jordan

Abstract What happens with data when the research process radically involves and engages those who are in the target group? How can we move towards collaborative insights by integrating our participants in the design of research, conduct of work, and, ultimately, its writing and dissemination? And how does this enable us to devise better futures when imagining such futures may be the very problem? Based on experimental research methods with Syrian refugee youth in Jordan, this article discusses how novel ways of engaging target groups in research can help push analyses in new directions. Collaborative methods, we argue, allow for 3 general analytical displacements that may help us work through the protracted nature of much humanitarian intervention and aid work: namely, moves from worldmaking to waymaking, from urgency to discernment, and from the biological to the biographical.

Comparative Study Of Dynamic Earthquake Analysis With Spectral Design And Time History Methods

Earthquakes are natural events that cannot be prevented by humans and their occurrence is very difficult to predict. In civil engineering, especially in the structural field, earthquake loads are a major problem in planning economical and safe building structures. This study aims to determine the comparison of earthquake structures with the Response Spectrum, Response Spectrum Matched, Time Histories, and Time Histories Matched methods on the magnitude of the natural vibration period of the structure, the basic shear force, mass participation, displacement, and deviation between levels. The results of this study that the period of natural vibration of the structure with the earthquake method RS 1.412 seconds, RSM 1.453 seconds, TH 1.453 seconds, and THM 1.453 seconds is between the lower limit of 1.054 seconds and the upper limit of 1.476 seconds, so it meets the requirements of SNI 1726:2019. The results of the base shear analysis showed that dynamic analysis is greater than static and the structural model meets the requirements that VDynamics > 100%. VStatic. The results of the analysis of building mass participation in various earthquake methods meet the provisions with results of more than 90%. The results of the analysis of displacements are obtained for the x-direction, the largest THM is 41.945 mm and for the y-direction, TH is 57.330 mm. The results of the drift ratio analysis are obtained for the results of the y-direction drift which is greater than the x-direction drift and permit control for all earthquake methods is safe and meets the requirements of SNI 1726:2019.

Experimental and numerical study on impact resistance of offshore wind turbine CFDST jacket

With the development of large-scale offshore wind turbines (OWT), the jacket foundation widely used to offshore wind turbines are at significant risk of collision damage from vessels and sea ice. In order to improve the impact resistance of hollow steel tube jacket foundation, a new type of concrete-filled double-skin steel tube (CFDST) jacket foundation is proposed. From the analysis of impact force, displacement, acceleration and energy consumption, the peak strain and acceleration of the jacket leg at the impact position are reduced by 57.1 % and 50.4 %, respectively. The deformation mechanism and failure mode of the two foundations under multiple impact loads were obtained by combining LS-DYNA software and test. After two impacts the hollow steel tube jacket was seriously dented and damaged in bending. However, after multiple pendulum impacts on a concrete-filled double-skin steel tube, only the supporting struts were bent, the indentation depth and displacement peak of the jacket leg are reduced by 76.9 % and 72.2 %, respectively, and the entire structure showed excellent impact resistance, overall bending stiffness and energy dissipation capacity. Finally, the experimental basis and theoretical analysis are provided for the application of concrete-filled double-skin steel tube jacket in large offshore wind turbines and the resistance to impact loads.

Research on a Super-Sub-Arc Bivariate Relative Angle Thermal Deformation Testing Method without Pitch Angle Limitation

In light of the current situation where no testing equipment is available for measuring thermal deformation of objects, this paper proposes a novel method for accurate and precise measurement. The method overcomes the limitations of previous approaches that relied on pitch angle. By utilizing the principle of biplane multiple reflections, a bivariate laser spot displacement analysis algorithm is devised to attain highly precise measurements of bivariate angles. Additionally, a temperature gradient comparison algorithm is introduced to calculate the indicator test results under specific temperature conditions. To validate the effectiveness and reliability of this method, a testing system is constructed and utilized. The results demonstrate that the thermal deformation angle change test achieves an impressive accuracy of 0.015″ and a rate of thermal deformation angle change of 0.3247″/°C. These values are in close agreement with the previously simulated analysis result of 0.359″/°C, with only a relative error of 9.55%. Therefore, the test results confirm the efficacy and reliability of this testing method along with the feasibility of the algorithm processing.

Hydrogen trapping and diffusion in polycrystalline nickel: The spectrum of grain boundary segregation

Hydrogen as an interstitial solute at grain boundaries (GBs) can have a catastrophic impact on the mechanical properties of many metals. Despite the global research effort, the underlying hydrogen-GB interactions in polycrystals remain inadequately understood. In this study, using Voronoi tessellations and atomistic simulations, we elucidate the hydrogen segregation energy spectrum at the GBs of polycrystalline nickel by exploring all the topologically favorable segregation sites. Three distinct peaks in the energy spectrum are identified, corresponding to different structural fingerprints. The first peak (−0.205 eV) represents the most favorable segregation sites at GB core, while the second and third peaks account for the sites at GB surface. By incorporating a thermodynamic model, the spectrum enables the determination of the equilibrium hydrogen concentrations at GBs, unveiling a remarkable two to three orders of magnitude increase compared to the bulk hydrogen concentration reported in experimental studies. The identified structures from the GB spectrum exhibit vastly different behaviors in hydrogen segregation and diffusion, with the low-barrier channels inside GB core contributing to short-circuit diffusion, while the high energy gaps between GB and neighboring lattice serving as on-plane diffusion barriers. Mean square displacement analysis further confirms the findings, and shows that the calculated GB diffusion coefficient is three orders of magnitude greater than that of lattice. The present study has a significant implication for practical applications since it offers a tool to bridge the gap between atomic-scale interactions and macroscopic behaviors in engineering materials.

Multi-stage slope displacement analysis based on real-time dynamic Newmark slider method

Based on the upper-bound limit analysis method and the real-time dynamic Newmark slider method, the internal and external power of the multi-stage slope under earthquake action is calculated at each moment, and the real-time yield acceleration coefficient and the horizontal displacement of the slope toe are obtained. The influence of soil parameters and geometric characteristics of the slope on the horizontal displacement of the slope toe under the seismic action is analyzed with a typical three-stage slope. The results indicate that the yield acceleration coefficient of the landslide shows an increasing trend during the sliding process, and the value of the horizontal displacement of the slope toe considering the real-time dynamics is smaller than the result without considering. Changing the geometric characteristics of the slope can improve the seismic performance of the multi-stage slope to a certain extent.

Strain, crack, stress and shape diagnostics of new and existing post-tensioned structures through distributed fibre optic sensors

Prestressed concrete is commonly used in the construction of safety–critical structures such as large-span girders or slabs. The article focuses on post-tensioned elements, in which curvilinear multiwire strands are tensioned after concrete’s hardening to transfer the compressive force to the concrete. The overall idea is to confront external forces and achieve extended benefits, e.g. longer spans or reduced cracking. However, the design, construction and maintenance of such elements are particularly challenging because of their complexity, including spatial stress state in the anchorage zones and also the standard features of concrete structures like heterogeneity, material imperfections and, most importantly, local discontinuities (cracks). Reliable diagnostic solutions are therefore essential for both new and existing components. Distributed fibre optic sensing (DFOS) allows the measurements to be taken continuously over the entire structural length and its advantages have already been proven in civil engineering applications, especially those related to concrete structures. However, the novelty of the presented research lies in 1) simultaneous analysis of strains, stresses, cracks and displacements (shape changes); 2) direct comparison of results from monolithic sensors embedded in the concrete (for new structures) and those installed in pre-made near-to-surface grooves (for existing structures); 3)the application of the embedded composite strain sensor to the bi-directional analysis of the stress field within the anchorage zones; 4) possibility of strain transfer analysis between the cracked concrete, cable duct, injection and prestressing tendon during mechanical bending tests. The DFOS-based strain, crack and displacement results were also compared with reference measurements made with conventional spot techniques, achieving very good compliance. The research proved that a well-designed DFOS-based system, including appropriate measurement techniques, optical sensors, installation methods and post-processing algorithms, is the relevant tool for the diagnostics of post-tensioned concrete structures.

NUMERICAL SIMULATION OF GAS AND WATER FILTRATION IN POROUS MEDIUM MICROMODELS

To select and justify effective compositions for limiting water inflow into gas wells, an understanding of the behavior of the multiphase system on the scale of individual pores is necessary. In turn, capillary forces depend on the interfacial tension and wettability of the pore surface. As part of this work, computational microfluidics methods were used using the OpenFOAM platform to analyze the effect of rock wettability on the features of two-phase filtration of water and gas in a T-shaped micromodel of a porous medium, which is a crack connected to an element of a porous matrix.
 A mathematical model was chosen that allows you to describe the movement of fluid in a fracture by the Navier-Stokes equation, and in elements of a porous matrix by the Darcy equation. A grid of a T-shaped micromodel of a porous medium was generated using a GMSH grid generator. The displacement of water by gas from the fracture and porous matrix was simulated. Multivariable analysis of water displacement by gas for hydrophobic and hydrophilic surface was carried out by varying wetting angles. The dependencies of the residual water of the micromodel on the contact angle and flow modes were conducted. It has been found that at low filtration rates, water enters the fracture from the porous medium, which blocks the direct flow of gas through the fracture. In the case of a hydrophilic surface, the water inflow from the porous matrix is greater than in the case of a hydrophobic surface, since blocking the fracture results in gas filtration through the porous medium and displacement of water therefrom. The proposed approach can be used to rank effective bottomhole treatment agents and select optimal filtration modes to limit water inflow into gas wells.

Parameter Identification of Frame Structures by considering Shear Deformation

This paper presents a method to identify the damages in frame structures with slender beams. This method adjusts the parameters of the structure to match the analytical and the measured displacements. The effect of transverse shear deformation on the nodal analytical displacement is analyzed, and the parameter identification of frame structures with slender beams is performed. The results demonstrate that parameter-identification accuracy can be considerably improved by considering the transverse shear deformation in the frame structure with slender beams. The proposed method can accurately identify the damages in frame structures with slender beams using displacement measurements.

Metamaterial‐Augmented Head‐Mounted Audio Module

AbstractRecent developments in metamaterial research have shown promising progress in overcoming the fundamental physical limitations of acoustics. While the majority of this research is curiosity‐driven and focused on fundamental physics, there has been a scarcity of acoustic metamaterials research that can have a direct and immediate impact on real‐world applications. In this study, an acoustic metamaterial inside a head‐mounted audio module is incorporate to achieve a 3–7 dB broadband sound pressure level (SPL) improvement in the bass range (50–700 Hz), which is the most challenging frequency range for radiation enhancement. The adoption of the acoustic metamaterial not only enhances voltage sensitivity near the intrinsic metamaterial resonance frequency, but also extends the broadband enhancement to a lower transducer resonance frequency by carefully engineering the metamaterial‐transducer resonant coupling. The improvement of the audio module is demonstrated through fully coupled electrical‐mechanical‐acoustical numerical simulations using finite element analysis, which are validated against comprehensive measurements including electrical impedance analysis, speaker diaphragm displacement analysis, voltage sensitivity and power sensitivity analysis, and spectrogram. This study not only offers a promising path to improve the audio module quality without increasing the size, but also represents an important milestone toward using acoustic metamaterial research to solve audio industry challenges.

Visualization of regional seismic response based on oblique photography and point cloud data

Efficient and realistic visualization of regional seismic response is of great significance for risk education and emergency response. This study proposes an efficient visualization framework for seismic response of regional buildings, which consists of three parts: (1) oblique photography-based three-dimensional (3D) point cloud modelling of regional buildings; (2) time-history response analysis of regional buildings; and (3) hybrid processing for dynamic visualization. Specifically, the unmanned aerial vehicle (UAV) is adopted for oblique photography. The building coordinate extraction with the least square method and point cloud data segmentation with the clustering algorithm are implemented for the pre-processing. The simplified multi-degree-of-freedom (MDOF) model is developed for the time-history displacement analysis of buildings. Then, the MDOF model is used to match the point cloud model of the buildings for visualization. Preset rendering parameters and dynamic geometrical updating are used to further improve the visualization quality. Taking the Southeast University Jiulonghu campus in Nanjing, China for example, a case study is conducted to validate the feasibility of the developed framework.

The LDL receptor is regulated by membrane cholesterol as revealed by fluorescence fluctuation analysis

Membrane cholesterol-rich domains have been shown to be important for regulating a range of membrane protein activities. Low-density lipoprotein receptor (LDLR)-mediated internalization of cholesterol-rich LDL particles is tightly regulated by feedback mechanisms involving intracellular sterol sensors. Since LDLR plays a role in maintaining cellular cholesterol homeostasis, we explore the role that membrane domains may have in regulating LDLR activity. We expressed a fluorescent LDLR-mEGFP construct in HEK293T cells and imaged the unligated receptor or bound to an LDL/DiI fluorescent ligand using total internal reflection fluorescence microscopy. We studied the receptor’s spatiotemporal dynamics using fluorescence fluctuation analysis methods. Image cross correlation spectroscopy reveals a lower LDL-to-LDLR binding fraction when membrane cholesterol concentrations are augmented using cholesterol esterase, and a higher binding fraction when the cells are treated with methyl-β-cyclodextrin) to lower membrane cholesterol. This suggests that LDLR’s ability to metabolize LDL particles is negatively correlated to membrane cholesterol concentrations. We then tested if a change in activity is accompanied by a change in membrane localization. Image mean-square displacement analysis reveals that unligated LDLR-mEGFP and ligated LDLR-mEGFP/LDL-DiI constructs are transiently confined on the cell membrane, and the size of their confinement domains increases with augmented cholesterol concentrations. Receptor diffusion within the domains and their domain-escape probabilities decrease upon treatment with methyl-β-cyclodextrin, consistent with a change in receptor populations to more confined domains, likely clathrin-coated pits. We propose a feedback model to account for regulation of LDLR within the cell membrane: when membrane cholesterol concentrations are high, LDLR is sequestered in cholesterol-rich domains. These LDLR populations are attenuated in their efficacy to bind and internalize LDL. However, when membrane cholesterol levels drop, LDL has a higher binding affinity to its receptor and the LDLR transits to nascent clathrin-coated domains, where it diffuses at a slower rate while awaiting internalization.

Octupole deformation in 143,145,146Ba

Gamma rays emitted by fission fragments of 252Cf and measured using the Gammasphere array continue to give insight into neutron rich nuclei. Using our high statistics data, we have reexamined high-spin states and linking transitions associated with octupole correlations in 143,145,146Ba. This has been a region of interest, when it was proposed that near 145Ba there was a region of octupole deformation. In an even-A system, it is possible that rotational band structures are explainable by simplex quantum numbers, s=+1 and s=−1. The previous bands including octupole bands in 143,145,146Ba have been extended. The new s=i octupole bands in 145Ba and new s=−1 octupole bands in 146Ba have been identified. In addition, collective model analysis of energy displacement, rotational frequency and B(E1)/B(E2) ratios have been carried out. Evidence of the rotational consequences of octupole deformation in even-even and even-odd isotopes is given. These nuclei have trends as rotation stabilizes the vibrational degrees of freedom. The experimental results are in agreement with theoretical calculations using the interacting boson and boson-fermion models that are based on a universal nuclear energy density functional.

Enhanced thermal conductivity in Ag-H2O nanofluids by nanoparticles of different shapes: Insights from molecular dynamics simulation

The mechanism of thermal conductivity enhancements and influential factors make a lot of sense in the intensive investigation of nanofluids. While numerous studies have explored the effect of solid–liquid interfacial layers on thermal conductivity improvement in water-based nanofluids with diverse applications, investigations into the intrinsic mechanisms underlying interfacial layers in relation to nanoparticle shape remain limited. The thermal conductivity of water-based Ag-H2O nanofluids was investigated using molecular dynamics simulations of non-equilibrium molecular dynamics (NEMD), with emphasis placed on the shape and volume fraction of nanoparticles. The influence of nanofluid volume fraction on thermal conductivity was revealed through visual analysis of 3D smoothed surface plots, highlighting the positive correlation between thermal properties and increasing volume fraction of nanoparticles. Moreover, the contribution of different shapes of silver nanoparticles to thermal conductivity enhancement demonstrated an increasing trend with the corresponding growth in surface-to-volume ratio (S/V values associated with different particle shapes). For the volume fraction of 1.5%, the minimum thermal conductivity enhancement of 22.75% was observed for the spherical shape, while the maximum thermal conductivity enhancement of 25.51% was achieved with the triple-platelet particles. Importantly, the comprehensive analysis of radial distribution function (RDF) and mean square displacement (MSD) indicated the positive effect of interfacial nanolayers influenced by nanoparticles of various shapes on the thermal conductivity of nanofluids. This study provides valuable insights into the impact of nanoparticle shape on the thermal properties of nanofluids, opening up promising prospects for future molecular dynamics simulations.

Analytical prediction for ground movements due to deep excavations in soils

This paper presents an analytical method to estimate surface and subsurface soil movements induced by deep excavations in the vertical and horizontal directions. Elastic and elastoplastic closed-form solutions for ground losses in the half-space are adopted, using the superposition method, to consider convergence and ovalization processes that occur within the soil mass due to displacements of the retaining wall; inputs include the shape and magnitude of the wall displacement profile to be selected based on design charts, monitoring data, or allowable level of resulting ground deformations. A parametric analysis illustrates (i) the effects on greenfield soil movements of the retaining wall’s deformation modes (cantilever, parabolic, composite, or kick-in), (ii) the influence of its displacement level, and (iii) the influence of aspects such as the soil’s ovalization and volumetric behaviour. Predictions of the proposed method are compared with empirical criteria, field data, and centrifuge results from the literature compiled for braced excavations in clays and sands. This comparison shows that the analytical approach provides reasonable predictions of excavation-induced soil deformations both at surface and subsurface levels, except for high normalized wall deflections when the analytical ground displacement field is wider and its maximum movements underestimate measured values. Finally, from the back-analyses of real data, a design guideline is suggested to select the relative ovalization depending on ground conditions and wall deflection mode.

Investigation on nano-grinding process of GaN using molecular dynamics simulation: Nano-grinding parameters effect

Nano-grinding is an essential step in ultra-precision machining for brittle material semiconductor workpieces in order to improve the surface quality and preserve strength prior to practical application. This study utilizes molecular dynamics (MD) method to conduct single-crystal gallium nitride (GaN) nano-grinding simulations under varying parameters. The damage mechanism of the surface/subsurface on the nanometer scale is explored through atomic displacement analysis, radial distribution function (RDF), phase transition, dislocation analysis, processing force, temperature distribution, and residual stress distribution. The machined surface quality and crystal structure distribution in the subsurface damage layer (SDL) are also examined, and a strong correlation is found between the parameters in nano-grinding. The nano-grinding speed is closely associated with the post-processing surface morphology, crystal phase transition, and temperature distribution in the GaN workpiece. Additionally, the ambient temperature has a considerable effect on the surface morphology and crystal phase transition. Moreover, the nano-grinding depth has a considerable influence on the surface morphology, phase transition, dislocation, processing force, and the temperature-dependent distribution of the residual stress in the GaN workpiece. This work reveals the relationship between the parameters and the mechanical properties of the machined surface in nano-grinding, and elucidates the damage mechanism of the subsurface, thus providing a helpful guide to the optimization of ultra-precision machining.

A New Index to Evaluate the Seepage Capacity of Water-Wet Sandstone Reservoirs

The water-wet sandstone reservoirs in the Liushagang Formation of the Beibuwan Basin has tremendous exploration potential for oil reserves in the South China Sea. However, owing to the weak correlations between petrophysical parameters and oil productivity, the production performance and seepage capacity showed significant differences in various reservoirs. The production performance of the field was evaluated by characterizing the mobility of two-phase flow through the concept of classical global mobility. However, global mobility still does not consider differential displacement pressure (DDP) and movable oil saturation (MOS). Therefore, a new index based on the Li–Horne model was established to simultaneously evaluate the seepage capacity of water-wet sandstone reservoirs, accounting for DDP and MOS. The detailed work stemming from the model included selecting water-wet sandstones with different lithologies and comparing the displacement effects of different flooding systems, oil viscosities, injection water salinities, pressure conditions, and MOS in multiple sets of parallel core samples. Finally, the new index was validated. A strong correlation was found between the new index and oil productivity per-unit differential pressure through displacement analysis of rock/oil/water, rock/oil/gas, and rock/oil/polymer systems on several core samples. The developed index for evaluating seepage capacity is suitable for different sandstones, flooding systems, oil viscosities, injection water salinities, pressure conditions, and productivity test data, thus providing insight into the production performance and seepage capacity parameters of water-wet sandstone reservoirs.

On-the-fly machine learning force field study of liquid-Al/α-Al2O3 interface

The atomic structure of the liquid Al/α-Al2O3 interface was investigated using on-the-fly machine learning force field based on first-principles calculations. We found that three different terminal surfaces of the liquid Al/α-Al2O3{0001} systems exhibited the same interfacial characteristics. Liquid Al atoms at the interface formed an Al-rich layer and several ordering layers. Analysis of mean square displacement and vibrational density of states indicated that the characteristics of Al-rich layer at the interface is close to solid, while liquid ordering layers possess a confined liquid nature. Furthermore, we simulated a larger system with more than 1000 atoms, which showed that periodic boundary conditions caused size effects that affected the ordering of the liquid atoms at the interface. Hence, the present study has the potential to generate substantial interest and inspire further research into the utilization of machine-learned force fields for simulating various liquid–solid interfaces.

Analysis of Landslide Displacement and Stress under the Condition of Overturning Failure of Fully Buried Anti-slide Piles

In this paper, on the basis of proving the basic consistency between numerical experiments and on-site physical experiments, a three-dimensional model of push pile FLAC3D was established. Based on relevant engineering analogies, parameters were selected to simulate and analyze the overturning failure mechanism of fully buried anti-slide piles. The research results indicate that the displacement of sand filling in front of the pile is significantly smaller than that of sand filling behind the pile. When approaching the failure load, a large area of uplift phenomenon appears at the top of the sliding body behind the pile; Most of the sand filling above the sliding surface showed a positive displacement along the x-axis, and the maximum displacement occurred at the top of the bulldozer. As the load increases, the sliding and upwelling area behind the pile tends to expand, and the vertical displacement at each point increases to a certain extent. At this time, the pile body is subjected to a "pull-out" effect from the surrounding sand.