Effect Of Surface Deformation Research Articles

Effect of liquid surface depression size on discharge characteristics and chemical distribution in the plasma-liquid anode system

Atmospheric pressure plasma-liquid interactions exist in a variety of applications, including wastewater treatment, wound sterilization, and disinfection. In practice, the phenomenon of liquid surface depression will inevitably appear. The applied gas will cause a depression on the liquid surface, which will undoubtedly affect the plasma generation and further affect the application performance. However, the effect of liquid surface deformation on the plasma is still unclear. In this work, numerical models are developed to reveal the mechanism of liquid surface depressions affecting plasma discharge characteristics and the consequential distribution of plasma species, and further study the influence of liquid surface depressions of different sizes generated by different helium flow rates on the plasma. Results show that the liquid surface deformation changes the initial spatial electric field, resulting in the rearrangement of electrons on the liquid surface. The charges deposited on the liquid surface further increase the degree of distortion of the electric field. Moreover, the electric field and electron distribution affected by the liquid surface depression significantly influence the generation and distribution of active species, which determines the practical effectiveness of the relevant applications. This work explores the phenomenon of liquid surface depression, which has been neglected in previous related work, and contributes to further understanding of plasma-liquid interactions, providing better theoretical guidance for related applications and technologies.

An assembly accuracy analysis approach of mechanical assembly involving parallel and serial connections considering form defects and local surface deformations

Tolerance analysis including tolerance model representation and assembly deviation propagation, is a key approach for predicting and controlling the assembly accuracy of mechanical product. In the current researches, the Non-Gaussian skin model shapes (NSMS) is a valid approach to represent tolerance model of parts considering form defects. However, there is a lack of valid methods to analyze the deviation propagation of mechanical assembly involving parallel and serial connections due to without considering the effect of local surface deformations between mating surfaces (LSDMS) in assembly process, which may affect the assembly accuracy analysis. In addition, the calculation of relative positioning deviation between mating surfaces (RPDMS) of parallel connection has not been combined with practical assembly process closely, which may lead to the loss of accuracy. To address above problems, this paper proposes an assembly accuracy analysis approach of mechanical assembly involving parallel and serial connections considering form defects and LSDMS. Firstly, an integrated Jacobian-NSMS model is presented based on NSMS and Unified Jacobian-Torsor model, which combines the advantages of efficient deviation propagation analysis and high-fidelity representation of tolerance. Secondly, based on the registration method and the difference surface method for solving RPDMS of serial connections, the RPDMS of parallel connection is obtained by performing algebraic operations combining with practical assembly process, by which the assembly involving parallel and serial connections is transformed into a new serial assembly, then the assembly deviation for mechanical assembly involving parallel and serial connections considering form defects and LSDMS can be calculated with the integrated Jacobian-NSMS model. Finally, a case study is presented to verify the proposed method, the result shows that there is different effect on assembly deviation between considering and without considering form defects and LSDMS, which indicates that the form defects and LSDMS have non-ignorable effect on assembly accuracy analysis of mechanical assembly involving parallel and serial connections. In addition, the result shows there is different effect on assembly deviation between considering and without considering practical assembly process in parallel connection. It is expected that the proposed method can help improve the assembly accuracy of mechanical assembly involving parallel and serial connections.

A novel machine learning and deep learning semi-supervised approach for automatic detection of InSAR-based deformation hotspots

Over the past two decades, Interferometric synthetic aperture radar (InSAR) has been invaluable for studying earth surface deformation and related effects. Deformation maps generated through multi-temporal InSAR processing methods are however difficult to interpret accurately by general individual users, decision-makers, and non-domain experts owing to the volume, variety, and velocity they are produced. This paper proposes a semi-supervised machine learning based information mining approach to simplify these deformation maps and detect hotspots by extracting prominent signals from time series deformation. The approach initially combines two machine learning based clustering methods named time series k-means (TSKM) and Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithms to derive clusters with unique spatiotemporal deformation behavior, using time series deformation output generated from Wavelet-based InSAR (WabInSAR) method. Clustering results generated from this unsupervised machine learning approach are later used as training labels to develop two deep learning models, one using long short term memory (LSTM) networks alone and another using a combination of LSTM and single-layer perceptron for supervised training. The developed LSTM and LSTM + Perceptron models efficiently learn from the cluster labels, reaching an accuracy of 97.3 %. Further, the deep learning models significantly reduce the computational time from orders of days (∼5) to hours (∼2) while training and from hours to minutes during prediction. We evaluate the developed approach over Los Angeles, a highly challenging area affected by umpteen deformation events that are challenging to categorize. The outcome of the proposed approach produces hotspots of deforming areas in Los Angeles, providing a generalized and more precise picture of events, much appreciable to non-domain experts. The approach can augment any of the multi-temporal InSAR processing chains and is applicable to different deformation prone sites, aiding in derivation of deformation hotspots from time series deformation maps.

Impact of ground surface subsidence caused by underground coal mining on natural gas pipeline

Underground mining of minerals is accompanied by a change in the rock mass geomechanical situation. This leads to the redistribution of stresses in it and the occurrence of unexpected displacements and deformations of the earth's surface. A significant part of the civil and industrial infrastructure facilities are located within the mine sites, where mining and tunneling operations are constantly conducted. Irrational planning of mining operations can lead to loss of stability and destruction of undermined facilities. Therefore, it is important to study the earth’s surface deformation processes during mining operations, which ensures safe and sustainable operating conditions. The research objective of this paper is to analyse the behaviour of a natural gas pipeline under the influence of underground mining activities, with a particular focus on understanding the effects of horizontal surface deformations and their potential impact on pipeline safety and structural integrity. Its performance and safety are determined on the basis of the found parameters of the earth's surface horizontal deformations and their comparison with permissible parameters characterizing the conditions for laying pipelines, depending on the mining-geological conditions and the degree of their undermining. Based on determined conditions for the safe undermining of the natural gas pipeline, it has been revealed that in its section between the PK212+40 and PK213+80 (140 m) pickets, the estimated parameters of the earth's surface horizontal deformations exceed their permissible values. This can cause deformation and damage to the pipeline. For the safe operation of the pipeline during the period of its undermining, in order to eliminate the hazardous impact of mining the longwall face, additional protection measures must be applied. It is therefore recommended that the gas pipeline between the PK212 and PK214+20 pickets be opened prior to the displacement process (200 m from the stoping face), thus reducing the density of the gas pipeline-soil system. Recommendations for controlling the earth’s surface deformations within the natural gas pipeline route are also proposed, which will ensure premature detection of the negative impact of mining operations.

Surface deformation and secondary effects of the January 18, 2021 (Mw 6.5) San Juan (Argentina) earthquake from remote sensing techniques

Surface deformation and secondary effects of the January 18, 2021 (Mw 6.5) San Juan (Argentina) earthquake from remote sensing techniques

Large-eddy simulation of free-surface turbulent channel flow over square bars

The results of large-eddy simulations of free-surface turbulent channel flow over spanwise-aligned square bars are used to investigate the effects of bed roughness and water surface deformations on the root-mean-squared velocity fluctuations, dispersive shear stress, double-averaged Reynolds shear stress, wake kinetic energy and double-averaged turbulent kinetic energy. Two bar spacings, corresponding to transitional and k-type roughness, at similar Reynolds and Froude numbers are considered. The main peak of all statistical quantities occurs at the bar crest height. The effects of a standing wave at the water surface in flow over k-type roughness is marked by a local peak under the water surface for all statistical quantities considered here except wall-normal and spanwise velocity fluctuations. Quadrant analysis shows that sweeps and ejections are the strongest events contributing to both dispersive and double-averaged Reynolds shear stress but their contributions are different for the two bar spacings. Examining the budgets of dispersive and double-averaged Reynolds shear stress reveals that the dominant terms of these stresses are pressure–strain correlation and pressure transport and the contribution of wake production is similar for both of these stresses but with opposite sign. In addition to the main role of the bars in consuming or producing wake kinetic energy through production and transport and convection, the standing wave at the water surface in flow over k-type roughness induces large convection in the bulk flow too. The dominant terms in the double-averaged turbulent kinetic energy budget are similarly production, transport and convection. Large shear production renders large temporal fluctuations than spatial fluctuations of flow variables. The interaction of bars, bed and water surface is seen in the convection term in flow over k-type roughness.

Comparative analysis between the laser beam welding and low current pulsed GMA assisted high-power laser welding by numerical simulation

By introducing the low current pulsed gas metal arc (GMA), the bridging ability of the laser beam welding (LBW) can be effectively improved. However, the impact mechanism of the additive GMA is hard to investigate by experimental methods. In this paper, the three-dimensional transient mass and heat transfer models of the low current pulsed GMA assisted high-power laser welding and single LBW are established. The pulsed arc and laser heat source models are optimized based on the arc morphology images, arc voltage and welding current. The drop transfer and arc pressure models are improved by comprehensively considering the effect of the molten pool surface deformation and the interaction of laser and arc on the arc heat flow distribution. Based on the established welding models, a comparative analysis is conducted to investigate the evolution characteristics of the temperature and flow fields in the molten pool. The simulated results show that the additive low current pulsed GMA in novel hybrid welding significantly increases the high temperature region of the molten pool, while allowing the liquid metal to expand transversely, thereby increasing the length and width of the molten pool. These greatly improve the bridging ability of LBW and extend its application range.

Effect of Wear-Induced Surface Deformation on Stick-Slip Friction of Galvanized Automotive Steels.

This study examined the influence of worn surfaces on the stick-slip friction of galvanized automotive steel and revealed the intrinsic role of surface topography parameters in the stick-slip friction with wear. The results show that the surface deformation induced by wear significantly affects the stick-slip friction. The stick-slip friction can be suppressed by increasing the vertical area of the surface deformation because of reductions in the difference between the static and kinetic friction coefficients. The friction behavior changes from stick-slip friction to smooth sliding when the skewness exceeds a critical value, thus suggesting that this parameter can be used as an effective surface topography parameter to describe the stick-slip friction of galvanized automotive steel with worn surfaces. The findings can help improve the understanding of the mechanism of the stick-slip friction of materials with worn surfaces and provide an approach to suppress the noise and vibration caused by the stick-slip friction of galvanized automotive steel.

High-resolution structure-from-motion models covering 160 km-long surface ruptures of the 2021 MW 7.4 Madoi earthquake in northern Qinghai-Tibetan Plateau

The 22 May 2021 MW 7.4 Madoi, Qinghai, China earthquake presented a rare opportunity to apply the modern unmanned aerial vehicle (UAV) photography method in extreme altitude and weather conditions to image surface ruptures and near-field effects of earthquake-related surface deformations in the remote Tibet. High-resolution aerial photographs were acquired in the days immediately following the mainshock. The complex surface rupture patterns associated with this event were covered comprehensively at 3–6 cm resolution. This effort represents the first time that an earthquake rupture in the interior of the Qinghai-Tibetan Plateau has been fully and systematically captured by such high-resolution imagery, with an unprecedented level of detail, over its entire length. The dataset has proven valuable in documenting subtle and transient rupture features, such as the significant mole-tracks and opening fissures, which were ubiquitous coseismically but degraded during the subsequent summer storm season. Such high-quality imagery also helps to document with high fidelity the fractures of the surface rupture zone (supplements of this paper), the pattern related to how the faults ruptured to the ground surface, and the distribution of off-fault damage. In combination with other ground-based mapping efforts, the data will be analyzed in the following months to better understand the mechanics of earthquake rupture related to the fault zone rheology, rupture dynamics, and frictional properties along with the fault interface.

Two dimensional computational model coupling myoarchitecture-based lingual tissue mechanics with liquid bolus flow during oropharyngeal swallowing

Biomechanical relationships involving lingual myoanatomy, contractility, and bolus movement are fundamental properties of human swallowing. To portray the relationship between lingual deformation and bolus flow during swallowing, a weakly one-way solid-fluid finite element model (FEM) was derived employing an elemental mesh aligned to magnetic resonance diffusional tractography (Q-space MRI, QSI) of the human tongue, an arbitrary Lagrangian-Eulerian (ALE) formulation with remeshing to account for the effects of lingual surface (boundary) deformation, an implementation of patterned fiber shortening, and a computational visualization of liquid bolus flow. Representing lingual tissue deformation in terms of its 2D principal Lagrangian strain in the mid-sagittal plane, we demonstrated that the swallow sequence was characterized by initial superior-anterior expansion directed towards the hard palate, followed by sequential, radially directed, contractions of the genioglossus and verticalis to promote lingual rotation (lateral perspective) and propulsive displacement. We specifically assessed local bolus velocity as a function of viscosity (perfect slip conditions) and observed that a low viscosity bolus (5 cP) exhibited maximal displacement, surface spreading and local velocity compared to medium (110 cP, 300 cP) and high (525 cP) viscosity boluses. Analysis of local nodal velocity revealed that all bolus viscosities exhibited a bi-phasic progression, with the low viscosity bolus being the most heterogeneous and fragmented and the high viscosity bolus being the most homogenous and cohesive. Intraoral bolus cohesion was depicted in terms of the distributed velocity gradient, with higher gradients being associated with increased shear rate and bolus fragmentation. Lastly, we made a sensitivity analysis on tongue stiffness and contractility by varying the degree of extracellular matrix (ECM) stiffness through effects on the Mooney-Rivlin derived passive matrix and by varying maximum tetanized isometric stress, and observed that a graded increase of ECM stiffness was associated with reduced bolus spreading, posterior displacement, and surface velocity gradients, whereas a reduction of global contractility resulted in a graded reduction of obtainable accommodation volume, absent bolus spreading, and loss of posterior displacement. We portray a unidirectionally coupled solid-liquid FEM which associates myoarchitecture-based lingual deformation with intra-oral bolus flow, and deduce that local elevation of the velocity gradient correlates with bolus fragmentation, a precondition believed to be associated with aspiration vulnerability during oropharyngeal swallowing.

Surface Deformation and Secondary Effects of the January 18th, 2021 (Mw 6.4) San Juan (Argentina) Earthquake from Remote Sensing Techniques

Surface Deformation and Secondary Effects of the January 18th, 2021 (Mw 6.4) San Juan (Argentina) Earthquake from Remote Sensing Techniques

Cylindrical phased array with adaptive nulling using eigen‐correlation technique

In this research work, eigen-correlation matrix based technique is developed for cylindrical antenna array to generate main beam and nulls simultaneously. The array complex weights (amplitude and phase) computed using the developed technique are used for single-beamforming, multi-beamforming, and beamforming with nulls steering simultaneously. The limitations of null steering range are investigated for different surface deformations of the cylindrical antenna array. The effects of surface deformations for different cylindrical radii on peak gain of main beam, half-power beamwidth, first-null beamwidth, and sidelobe level is also investigated. It is concluded that the developed eigen-correlation matrix based technique for cylindrical antenna array can be used for desired main beam generation and nulls steering simultaneously. The MATLAB, CST, and measurement validation of eight elements microstrip cylindrical phased array for single/multi-beams steering and adaptive nulling capability is demonstrated. This in turn makes the cylindrical phased array with adaptive nulling, a potential candidate suitable for use on fuselage portion of aircraft, airport surveillance radars, and mobile communication applications.

Spatially developing supersonic turbulent boundary layer subjected to static surface deformations

The effects of static surface deformations on a spatially developing supersonic boundary layer flow at Mach number M=4 and Reynolds number Reδin≈49300, based on inflow boundary layer thickness (δin), are analyzed by performing large eddy simulations. Two low-order structural modes of a rectangular clamped surface panel of dimensions ≈33δin×48δin are prescribed with modal amplitudes of δin. The effects of these surface deformations are examined on the boundary layer, including changes in the mean properties, thermal and compressibility effects and turbulence structure. The results are analyzed in the context of deviations from concepts typically derived and employed for equilibrium turbulence. The surface deflections, to some degree, modify the correlations that govern both Morkovin’s hypothesis and strong Reynolds analogy away from the wall, whereas in the near-wall region both the hypotheses breakdown. Modifications to the turbulence structure due to the surface deformations are elucidated by means of the wall pressure two-point correlations and anisotropy invariant maps. In addition to the amplification of turbulence, such surface deformations lead to local flow separation, instigating low-frequency unsteadiness. One consequence of significance to practical design is the presence of low frequency unsteadiness similar to that encountered in impinging or ramp shock boundary layer interactions.

Deformation-induced topographic effect due to shallow dyke: Etna December 2018 fissure eruption case study

Gravitational effect of surface deformation is in 4D microgravimetry treated as the deformation-induced topographic effect (DITE). The DITE field is computed using Newtonian volumetric integration which requires high resolution digital elevation model (DEM) and vertical displacement field in areal form. If only elevation changes on benchmarks of the gravimetric network are available, instead of the vertical displacement field, the DITE on benchmarks can be evaluated only approximately, using a planar Bouguer or a normal free-air-effect (nFAE) approximation. Here we analyze the adequacy and accuracy of these two approximations in a case study for the December 2018 fissure eruption on Etna accompanied by significant surface deformation caused primarily by a relatively shallow dyke. The outcome is that in volcanic areas of similar morphology as that over the Etna summit area, and for surface deformation fields due to relatively shallow dykes, neither the Bouguer nor the nFAE approximation of the DITE is accurate enough. In such situations the residual gravity changes should be computed with both the Bouguer and nFAE corrections and interpreted as two marginal cases. In addition we analyze also a correction for the effect of benchmark elevation change based on the topographically modelled (predicted) vertical gradient of gravity (VGG) meant to approximate the in-situ VGG values at benchmarks. This correction does not appear suitable to approximate the DITE in conditions of our case study or in broader sense.

Precision Assembly Simulation of Skin Model Shapes Accounting for Contact Deformation and Geometric Deviations for Statistical Tolerance Analysis Method

Tolerance analysis methods, which are important to achieve a balance between manufacturing costs and functional requirements, have been studied and improved over the last 30 years. This paper proposes a new method to improve the precision of assembly simulation for statistical assembly simulation; by investigating the effect of the geometric deviations and mechanical behaviors of assembly contact on the stack-up assembly deviation by combining the recent theories on the tolerance analysis of rigid bodies and local contact deformation. To improve the precision of the tolerance analysis, real parts with form defects were simulated with the help of non-nominal skin model shapes. The SMSs were first considered to be rigid, and a quadratic optimization-based method for the rigid body displacement was used to calculate the initial contact points of all the SMSs. Next, contact deformation, following Hertzian contact theory, occurred at the initial contact points, which changed the relative positions of the SMSs in the subsequent interactions. The iteration process was convergent, and the final simulation for tolerance analysis could be generated after several iterations. Case studies demonstrated the practicality of the proposed method. Their actual assembly deviations were simulated by combining the effects of geometric deviations and local surface deformations. Since the proposed tolerance analysis framework based on statistical assembly simulation, it is expected to control the functional requirements of mechanical assemblies with much rough tolerance design and help optimize the tolerance in the future.

Novel treatment of the deformation–induced topographic effect for interpretation of spatiotemporal gravity changes: Laguna del Maule (Chile)

In volcano gravimetry, when analyzing residual spatiotemporal (time-lapse) gravity changes, the accurate deformation-induced topographic effect (DITE) should be used to account for the gravitational effect of surface deformation. Numerical realization of DITE requires the deformation field available in grid form. We compute the accurate DITE correction for gravity changes observed at the Laguna del Maule volcanic field in Chile over three nearly annual periods spanning 2013–2016 and compare it numerically with the previously used free-air effect (FAE) correction. We assess the impact of replacing the FAE by DITE on the model source parameters of analytic inversion solutions and apply a new inversion approach based on model exploration and growing source bodies. The new inversion results based on the DITE correction shift the position of the mass intrusion upwards by a few hundred meters and lower the total mass of the migrated fluids to roughly a half, compared to the inversion results based on the local-FAE correction. Our new Growth inversion results indicate that vertical dip-slip faults beneath the lake, as well as the Troncoso fault play active roles in hosting migrating liquid. We also show that for the study period, the DITE at Laguna del Maule can be accurately evaluated by the planar Bouguer approximation, which only requires the availability of elevation changes at gravity network benchmarks. We hypothesize that this finding may be generalized to all volcanic areas with flatter or less rugged terrain and may modify interpretations based on the commonly used FAE corrections.

Considerations of form defects and surface deformations for tolerance analysis of cylindrical components

The modeling and simulation of cylindrical surfaces with consideration of form defects have led to considerable research outcomes in the field of Computer-Aided Tolerancing (CAT). However, further consideration of surface deformations caused by external forces still remains a challenge. To address this issue, this paper properly considers the form defects and surface deformations for tolerance analysis of cylindrical components. First, form defects are considered by modeling skin model shapes of cylindrical surfaces. Afterwards, the tight fit and loose fit of a pair of cylindrical surfaces are identified, and the simulation methods of their positioning are presented. Specifically, for tight fit situation, a k-d tree based Iterative Closest Point (ICP) algorithm is used, and for loose fit situation, the constrained registration approach is adopted. Moreover, a Conjugate Gradient-Fast Fourier Transform (CG-FFT) method is presented for the consideration of surface deformations. In addition, simulations of given examples are conducted, which show the considerable effects of form defects and surface deformations. The simulations may also help determine the best performance of the to-be-assembled cylindrical components.

Analysis of the Control Effect and Parameter Optimisation of Urban Surface Deformation in Underground Coal Mining with Solid Backfilling

To solve the problems of surface deformation and destruction of buildings caused by urban mining and realise the coordinated development of mining cities, the solid backfilling method was used to extract coal resources beneath the buildings of Tangshan. Based on surface deformation monitoring data of the continuously operating reference station (CORS) system for the past 5 years, the surface deformation process caused by solid backfilling was analysed. The final results revealed a maximum surface subsidence of 66 mm in the T zone coal area and 31 mm in the F zone area. Furthermore, the surface control effects of the caving method and the solid backfilling method were compared and analysed, and it was shown that solid backfilling could meet the surface building setup requirements. Moreover, based on the probability integral method, the effects on surface deformation due to the surface length of the F zone, compression ratio, and coal pillar width were analysed, and the effects on the prediction results due to the subsidence factor, tangent of the major effective angle, and offset distance of the inflection point were studied. The results showed that the compression ratio is the main factor controlling the surface deformation and that it should be kept above 80% for solid backfilling of urban mines. The subsidence factor should be 0.82, and the tangent of the major effective angle should be 2.15 when the surface subsidence of solid backfilling is to be predicted. This paper provides a technical reference for the realisation of urban mining with solid backfilling.

Polytope-based tolerance analysis with consideration of form defects and surface deformations

ABSTRACT Tolerance analysis aims to evaluate the functional requirement of mechanical assemblies in the design stage. As one of the typical tolerance analysis methods, the polytope model has shown great potential in Computer-Aided Tolerancing (CAT) field based on a series of constraints. However, existing research outcomes on this topic rarely consider form defects and the combined effects of form defects and surface deformations. This limitation may cause inaccuracy of tolerance analysis results. Hence, this paper integrates form defects and surface deformations in polytope-based tolerance analysis. Specifically, form defects are considered based on the concept of Skin Model Shapes and surface deformations are calculated based on a Conjugate Gradient-Fast Fourier Transform (CG-FFT) method. Then, the modeling method of the new polytope model is elaborated based on surface types and different types of constraints. Moreover, a case study is conducted to explain the procedure of polytope-based tolerance analysis. Through operations of the polytopes, tolerance analysis results are obtained, and the comparison with conventional polytope analysis results shows the considerable effects of form defects and surface deformations. It is expected that the proposed method can have a more realistic and accurate analysis result because of its consideration of real surface contact status.

Effect of surface deformation on biocompatibility of biomedical alloys

In this study, biocompatibility of Co-29Cr-5Mo (CCM), 316L steel (316L) and Ti-6Al-4V (TC4) alloys after surface plastic deformation under the condition comparable to the human ankle activities were investigated in details. Biocompatibility of all alloys decreases after surface deformation, while it is most significantly observed in CCM alloy. The different responses of biocompatibility are related to the corresponding microstructure evolution during surface deformation: martensitic phase transformation, dislocation slipping and mechanical twinning in CCM alloy result in the extremely localized microstructure, giving rise to the obviously decreased corrosion resistance or biocompatibility; quite homogenous microstructure after surface deformation leads to the slightly decreased corrosion resistance or biocompatibility in both 316L and TC4 alloys, since the surface deformation is dominated by slipping in 316L and by both slipping and a few mechanical twinning in TC4.