In this paper,we call a tuple consisting of 3-Lie algebra and a higher derivation on it a 3-LieHDer pair.We introduce a cohomology theory of 3-LieHDer pairs.Next,we interpret the second cohomology group as the space o...In this paper,we call a tuple consisting of 3-Lie algebra and a higher derivation on it a 3-LieHDer pair.We introduce a cohomology theory of 3-LieHDer pairs.Next,we interpret the second cohomology group as the space of all isomorphism classes of abelian extensions.Finally,we consider formal deformations of 3-LieHDer pairs that are governed by the cohomology with self-coefficient.展开更多
The modifiedλ-differential Lie-Yamaguti algebras are considered,in which a modifiedλ-differential Lie-Yamaguti algebra consisting of a Lie-Yamaguti algebra and a modifiedλ-differential operator.First we introduce t...The modifiedλ-differential Lie-Yamaguti algebras are considered,in which a modifiedλ-differential Lie-Yamaguti algebra consisting of a Lie-Yamaguti algebra and a modifiedλ-differential operator.First we introduce the representation of modifiedλ-differential Lie-Yamaguti algebras.Furthermore,we establish the cohomology of a modifiedλ-differential Lie-Yamaguti algebra with coefficients in a representation.Finally,we investigate the one-parameter formal deformations and Abelian extensions of modifiedλ-differential Lie-Yamaguti algebras using the second cohomology group.展开更多
A holistic and precise assessment of retaining wall deformations is critical for on-site risk management of large combined deep excavation projects,where the risk-related points are highly dispersed,evolving,and inter...A holistic and precise assessment of retaining wall deformations is critical for on-site risk management of large combined deep excavation projects,where the risk-related points are highly dispersed,evolving,and interacting.Despite extensive exploration of this topic in previous studies,the omission of intricate spatiotemporal characteristics of wall deformations has resulted in diminished prediction accuracy and stability.To mitigate this deficiency,a spatiotemporal characteristics matrix for all data points and time series was first generated for a deep excavation scenario and used as input for a new hybrid model that combines convolutional neural network(CNN)and long short-term memory(LSTM)with incorporated attention mechanism(CNN-LSTM-Att),which enables the cross-learning mechanism and improves interpretability.In addition,by leveraging the attention weight,a new risk assessment index for retaining wall deformations across various scenarios was formulated.Then the proposed method was applied in a large combined deep excavation in Shanghai,China.The results show that:(1)The incorporation of fedin characteristic data and the attention mechanism enables the proposed method to produce satisfactory prediction results for the holistic spatiotemporal distribution of a large combined excavation;(2)Compared with other published models,the proposed model shows much better prediction accuracy,interpretability,and stability,especially in medium-and long-term predictions;and(3)The new risk assessment index serves as a reliable decision-making tool for assessing the risk evolution of retaining wall deformations and provides valuable guidance for effective risk management in multi-scenario excavation projects.展开更多
The influences of multiple plastic deformations on microstructure and mechanical properties of 7A04-T6 alloy by isothermal compression experiments in different passes deformation on the 6300 kN extrusion press. The ex...The influences of multiple plastic deformations on microstructure and mechanical properties of 7A04-T6 alloy by isothermal compression experiments in different passes deformation on the 6300 kN extrusion press. The experimental results showed that the strength and elongation of 7A04-T6 alloy were increased firstly and then decreased as the deformation pass increases at above 400 ℃. The grains of 7A04-T6 alloy was refined firstly and then grow, the grain was become refinement after four deformations under this experimental conditions. The second phase η (MgZn2) in the matrix would precipitate after solution, precipitation strengthening taking place. It is obvious that the number of second phase which dissolve into the matrix will increase as the deformation pass increasing. So the tensile strength reached the highest after four deformations, is 590.9 MPa, yield strength is 532.5 MPa, and elongation is 12.4%. After four deformations of 7A04-T6 alloy, tensile fracture surface of samples was composed of the deep and uniform dimples, belonging to ductile fracture. Therefore, 7A04-T6 alloy has better comprehensive mechanical properties after four deformations.展开更多
This paper presents the results of numerical simulations carried out to confirm the influence of former mining activities on deformation of the mining terrain.The assessment of deformation changes was carried out with...This paper presents the results of numerical simulations carried out to confirm the influence of former mining activities on deformation of the mining terrain.The assessment of deformation changes was carried out with the use of FLAC3 D program based on the finite difference method.Numerical calculations were carried out for the example of actual mining operations in seams 703/1-2 and 707/2 of‘‘Marcel"Coal Mine.Taking into account the influence of the model’s plastic features and the so-called activation of a higher occurring seam in conducted simulations enabled obtaining a very good description of the measured subsidence.Based on the results one may state that numerical model can be used to assess the influence of former mining activities and the direction of conducted exploitation on deformations of the mining terrain.These factors are not recognized by geometric-integral theories commonly used for predicting the influence of mining operations on the surface.The results presented in this paper confirm that the applied method of simulating the phenomenon of reactivation of post-mining goafs is correct.展开更多
In this paper,we study how coseismic deformations calculated in 1066 Earth models are affected by how the models treat Earth discontinuities.From the results of applying models 1066A(continuous)and 1066B(discontinuous...In this paper,we study how coseismic deformations calculated in 1066 Earth models are affected by how the models treat Earth discontinuities.From the results of applying models 1066A(continuous)and 1066B(discontinuous),we find that the difference in Love numbers of strike-slip and horizontal tensile sources are bigger than dip-slip and vertical tensile sources.Taken collectively,discontinuities have major effects on Green’s functions of four independent sources.For the near-field coseismic deformations of the 2013 Okhotsk earthquake(Mw 8.3),the overall differences between theoretical calculations in vertical displacement,geoid,and gravity changes caused by discontinuities are 10.52 percent,9.07 percent and 6.19 percent,with RMS errors of 0.624 mm,0.029 mm,and 0.063μGal,respectively.The difference in far-field displacements is small,compared with GPS data,and we can neglect this effect.For the shallow earthquake,2011 Tohoku-Oki earthquake(Mw 9.0),the differences in near-field displacements are 0.030 m(N-S),0.093 m(E-W),and 0.025 m(up-down)in our study area with the ARIA slip model,which gives results closer to GPS data than those from the USGS model.The difference in vertical displacements and gravity changes on the Earth’s surface caused by discontinuities are larger than 10 percent.The difference in the theoretical gravity changes at spatially fixed points truncated to degrees 60,as required by GRACE data,is 0.0016μGal and the discrepancy is 11 percent,with the theoretical spatial gravity changes from 1066B closer to observations than from 1066A.The results show that an Earth model with discontinuities in the medium has a large effect on the calculated coseismic deformations.展开更多
This paper presents the results of a 2017 study conducted by the National Institute for Occupational Safety and Health(NIOSH), Pittsburgh Mining Research Division(PMRD), to evaluate the effects of longwall-induced sub...This paper presents the results of a 2017 study conducted by the National Institute for Occupational Safety and Health(NIOSH), Pittsburgh Mining Research Division(PMRD), to evaluate the effects of longwall-induced subsurface deformations within a longwall abutment pillar under deep cover. The 2017 study was conducted in a southwestern Pennsylvania coal mine, which extracts 457 m-wide longwall panels under 361 m of cover. One 198 m-deep, in-place inclinometer monitoring well was drilled and installed over a 45 m by 84 m center abutment pillar. In addition to the monitoring well, surface subsidence measurements and underground coal pillar pressure measurements were conducted as the 457 m-wide longwall panel on the south side of the abutment pillar was being mined. Prior to the first longwall excavation, a number of simulations using FLAC3D^(TM) were conducted to estimate surface subsidence, increases in underground coal pillar pressure, and subsurface horizontal displacements in the monitoring well. Comparisons of the pre-mining FLAC3D simulation results and the surface, subsurface,and underground instrumentation results show that the measured in-place inclinometer casing deformations are in reasonable agreement with those predicted by the 3D finite difference models. The measured surface subsidence and pillar pressure are in excellent agreement with those predicted by the 3D models.Results from this 2017 research clearly indicate that, under deep cover, the measured horizontal displacements within the abutment pillar are approximately one order of magnitude smaller than those measured in a 2014 study under medium cover.展开更多
Soil shear wave velocity has been recognized as a governing parameter in the assessment of the seismic response of slopes.The spatial variability of soil shear wave velocity can influence the seismic response of slidi...Soil shear wave velocity has been recognized as a governing parameter in the assessment of the seismic response of slopes.The spatial variability of soil shear wave velocity can influence the seismic response of sliding mass and seismic displacements.However,most analyses of sliding mass response have been carried out by deterministic models.This paper stochastically investigates the effect of random heterogeneity of shear wave velocity of soil on the dynamic response of sliding mass using the correlation matrix decomposition method and Monte Carlo simulation(MCS).The software FLAC 7.0 along with a Matlab code has been utilized for this purpose.The influence of statistical parameters on the seismic response of sliding mass and seismic displacements in earth slopes with different inclinations and stiffnesses subject to various earthquake shakings was investigated.The results indicated that,in general,the random heterogeneity of soil shear modulus can have a notable impact on the sliding mass response and that neglecting this phenomenon could lead to underestimation of sliding deformations.展开更多
Parallel kinematic machines have drawn considerable attention and have been widely used in some special fields.However,high precision is still one of the challenges when they are used for advanced machine tools.One of...Parallel kinematic machines have drawn considerable attention and have been widely used in some special fields.However,high precision is still one of the challenges when they are used for advanced machine tools.One of the main reasons is that the kinematic chains of parallel kinematic machines are composed of elongated links that can easily suffer deformations,especially at high speeds and under heavy loads.A 3-RRR parallel kinematic machine is taken as a study object for investigating its accuracy with the consideration of the deformations of its links during the motion process.Based on the dynamic model constructed by the Newton-Euler method,all the inertia loads and constraint forces of the links are computed and their deformations are derived.Then the kinematic errors of the machine are derived with the consideration of the deformations of the links.Through further derivation,the accuracy of the machine is given in a simple explicit expression,which will be helpful to increase the calculating speed.The accuracy of this machine when following a selected circle path is simulated.The influences of magnitude of the maximum acceleration and external loads on the running accuracy of the machine are investigated.The results show that the external loads will deteriorate the accuracy of the machine tremendously when their direction coincides with the direction of the worst stiffness of the machine.The proposed method provides a solution for predicting the running accuracy of the parallel kinematic machines and can also be used in their design optimization as well as selection of suitable running parameters.展开更多
In this paper,we introduce the representation and cohomology theory of Lie-Yamaguti color algebras.Furthermore,we introduce the notions of generalized derivations of Lie-Yamaguti color algebras and present some proper...In this paper,we introduce the representation and cohomology theory of Lie-Yamaguti color algebras.Furthermore,we introduce the notions of generalized derivations of Lie-Yamaguti color algebras and present some properties.Finally,we study linear deformations of LieYamaguti color algebras,and introduce the notion of a Nijenhuis operator on a Lie-Yamaguti color algebra,which can generate a trivial deformation.展开更多
In this study, the relative gravity data(2012 e2015), GPS data-derived horizontal deformation(2011 e2014) and the background vertical deformation from the leveling measurements(1970 e2011) in the northeastern margin o...In this study, the relative gravity data(2012 e2015), GPS data-derived horizontal deformation(2011 e2014) and the background vertical deformation from the leveling measurements(1970 e2011) in the northeastern margin of Tibetan Plateau were processed to systematically analysis the mechanism of temporalespatial patterns and the relationship with Menyuan Ms6.4 earthquake. It can be summarized in the following: 1) The regional gravity changes, the GPS and the vertical deformational showed an intense spatial relationship: the gravity increased along with the direction of horizontal movement, and decreased with the crustal uplift and vice versa, which reflected the inherited characteristics of geotectonic activities. 2) The crustal deformations were closely related to the active faults. The contour lines of gravity changes and vertical deformation were generally along with the Qilian-Haiyuan fault(strike is NWW), and the crustal horizontal deformation showed left-lateral strike slip motion near the Qilian-Haiyuan fault. 3) Menyuan Ms6.4 earthquake occurred in the high negative gravity variation area and a high gradient formed in regions, positive and negative variation of gravity amount to 110 m Gal.Specifically, a borderline of positive and negative gravity located in the south of epicenter along the north edge of Qilianshan fault and Lenglongling fault, as well as the vertical and/or horizontal deformation is intensely. The extrusion deformation, surface compression rate and gravity changes were obvious near the epicenter of 2016 Menyuan Earthquake.展开更多
Line heating process is a very complex phenomenon as a variety of factors affects the amount of residual deformations. Numerical thermal and mechanical analysis of line heating for prediction of residual deformation i...Line heating process is a very complex phenomenon as a variety of factors affects the amount of residual deformations. Numerical thermal and mechanical analysis of line heating for prediction of residual deformation is time consuming. In the present work dimensional analysis has been presented to obtain a new relationship between input parameters and resulting residual deformations during line heating process. The temperature distribution and residual deformations for 6 mm, 8 mm, 10 mm and 12 mm thick steel plates were numerically estimated and compared with experimental and published results. Extensive data generated through a validated FE model were used to find co-relationship between the input parameters and the resulting residual deformation by multiple regression analysis. The results obtained from the deformation equations developed in this work compared well with those of the FE analysis with a drop in the computation time in the order of 100 (computational time required for FE analysis is around 7 200 second to 9 000 seconds and where the time required for getting the residual deformation by developed equations is only 60 to 90 seconds).展开更多
There are relatively few studies on large rotation or deformation by means of the three-dimensional(3D)numerical manifold method(NMM).A new modified symmetric and antisymmetric decomposition(MSAD)theory is developed a...There are relatively few studies on large rotation or deformation by means of the three-dimensional(3D)numerical manifold method(NMM).A new modified symmetric and antisymmetric decomposition(MSAD)theory is developed and implemented into the 3D NMM,eliminating the false-volume expansion and false-rotation strain/stress problems.The Jaumann rate is used to measure the material rotation,and the geometric stiffness built on the Jaumann rate is deduced.The incremental formulas of the MSAD-based 3D NMM and a practical guide on the implementation of the MSAD theory are given in detail and exemplified.The new theory and formulas can be applied to analyze both large rotation and large deformation problems.Based on the hypoelasto-plasticity theory and the unified strength theory,the unified yield criterion with associated flow rule is implemented into the MSAD-based 3D NMM.Several typical examples are studied,showing the advantage and potential of the new MSAD theory and the MSAD-based 3D NMM.展开更多
Objective To study the effect of changing heart rate on the ocular pulse and optic nerve head deformations with a viscoelastic lamina cribrosa.Methods An FE model of a healthy eye was reconstructed.The choroid was bip...Objective To study the effect of changing heart rate on the ocular pulse and optic nerve head deformations with a viscoelastic lamina cribrosa.Methods An FE model of a healthy eye was reconstructed.The choroid was biphasic and consisted of a solid phase(connective tissues)and a fluid phase(blood).The LC was viscoelastic as characterized by a stress-relaxation test.We applied arterial pressures at 18 entry sites(posterior ciliary arteries)and venous pressures at 4 exit sites(vortex veins).The heart rate was varied from 60 bpm to 120 bpm(increment:20 bpm).We reported the ocular pulse amplitude(OPA),pulse volume,optic nerve head(ONH)deformations and the dynamic modulus of the LC at different heart rates.Results With an increasing heart rate,the OPA decreased by 0.04 mmHg for every 10 bpm increase.The pulse volume also exhibited a linear relationship with heart rate,and decreased by 0.13 L.In addition,the storage modulus and the loss modulus of the LC center increased by 0.014 MPa and 0.04 MPa,respectively for every 10 pm increase in heart rate.Conclusions Our model predicted that the OPA,the pulse volume the ONH deformation decreased at a faster heartrate.We also found that the viscoelastic LC became stiffer with an increasing heart rate.Further studies are required to explore the potential links with the vascular dysregulation and axonal loss in glaucoma.展开更多
Terrestrial water storage(TWs)variations are associated with water mass movements,which may cause the deformation displacements of the Global Navigation Satellite System(GNSS)stations.This study investigates the spati...Terrestrial water storage(TWs)variations are associated with water mass movements,which may cause the deformation displacements of the Global Navigation Satellite System(GNSS)stations.This study investigates the spatio-temporal Tws variations and addresses the relationship between deformation variations observed in the Huang-Huai-Hai River Basin(HHHRB)and local hydrological features.Results indicate that the vertical velocities at the GNSS stations induced by TWS changes are relatively small,and the impacts of the terrestrial water storage changes are mainly reflected in the changes of seasonal characteristics.Although there is a downward TWS trend from 2011 to 2022 in most HHHRB areas,velocities from the vertical displacements of both Gravity Recovery and Climate Experiment(GRACE)and GRACE Follow-On(GFO)and the GNSS reflect that the HHHRB is undergoing an uplift process,while the magnitude of the GRACE/GFO derived velocities is much smaller than that of the GNSS solutions.Common hydrological deformations estimated from GRACE/GFO and GNSS measurements reveal that the TWS-derived displacements can explain 54.5%of the GNSS seasonal variations,with the phases of terrestrial water storage advancing by about one month relative to GNss common signal phases.Moreover,the decrease of the groundwater storage in the HHHRB has been accelerating since 2008.After reaching its lowest level around mid-2020,it began to rise rapidly,which might be closely related to the implementation of the South-North Water Transfer Central Project.展开更多
Based on Hamilton＇s principle, a new kind of fully coupled nonlinear dynamic model for a rotating rigid-flexible smart structure with a tip mass is proposed. The geometrically nonlinear effects of the axial, transver...Based on Hamilton＇s principle, a new kind of fully coupled nonlinear dynamic model for a rotating rigid-flexible smart structure with a tip mass is proposed. The geometrically nonlinear effects of the axial, transverse displacement and rotation angle are considered by means of the first-order approximation coupling （FOAC） model theory, in which large deformations and the centrifugal stiffening effects are considered. Three kinds of systems are established respectively, which are a structure without piezoelectric layer, with piezoelectric layer in open circuit and closed circuit. Several simulations based on simplified models are presented to show the differences in characteristics between structures with and without the tip mass, between smart beams in closed and open circuit, and between the centrifugal effects in high speed rotating state or not. The last simulation calculates the dynamic response of the structure subjected to external electrical loading.展开更多
Experimental crystallographic structural parameters of a range of metaled meso-substituted and unsubstituted porphyrins were reviewed to show how far the meso-substitution by any functional group and the insertion of ...Experimental crystallographic structural parameters of a range of metaled meso-substituted and unsubstituted porphyrins were reviewed to show how far the meso-substitution by any functional group and the insertion of metal in the porphyrins core macrocycle may affect the geometry. The analysis of twists and angles has shown two kinds of distortions: external [T(C<sup>β</sup>-C<sup>α</sup>-C<sup>meso</sup>-X<sup>n</sup>) and T(C<sup>β</sup>-C<sup>α</sup>-C<sup>meso</sup>-C<sup>α</sup>)] and internal [T(N<sup>m</sup>-C<sup>α</sup>-C<sup>meso</sup>-X<sup>n</sup>) and T(N<sup>n</sup>-C<sup>α</sup>-C<sup>meso</sup>-C<sup>α</sup>)] with averages of [+6°and –6°] and [–5°and +5°], respectively. In the meso-substituted case, the external and internal twists C<sup>β</sup>-C<sup>α</sup>-C<sup>meso</sup>-X and N-C<sup>α</sup>-C<sup>meso</sup>-X, respectively are oppositely orientated. Similar effect is observed in meso-unsubstituted of C<sup>β</sup>-C<sup>α</sup>- C<sup>meso</sup>-H and N-C<sup>α</sup>-C<sup>meso</sup>-H. However, the external distortions are more significant than internal. Considering the same order, the limit of distortions is [97°and 132°(–48°)] for external and [91°(–89°) and 52°] for internal. In the two cases, the substituents have opposite directions of distortions. The meso-substituted porphyrins have a high limit of twisting than usubstituted one, depending of the weight of substituents. The average of the bond angular deformations is 168°, almost planar. However, the limit of angular deformation is 94°.展开更多
We propose a method to construct the integrable Rosochatius deformations for an integrable couplingsequations hierarchy.As applications, the integrable Rosochatius deformations of the coupled CKdV hierarchy withself-c...We propose a method to construct the integrable Rosochatius deformations for an integrable couplingsequations hierarchy.As applications, the integrable Rosochatius deformations of the coupled CKdV hierarchy withself-consistent sources and its Lax representation are presented.展开更多
Background The accurate(quantitative)analysis of 3D face deformation is a problem of increasing interest in many applications.In particular,defining a 3D model of the face deformation into a 2D target image to capture...Background The accurate(quantitative)analysis of 3D face deformation is a problem of increasing interest in many applications.In particular,defining a 3D model of the face deformation into a 2D target image to capture local and asymmetric deformations remains a challenge in existing literature.A measure of such local deformations may be a relevant index for monitoring the rehabilitation exercises of patients suffering from Par-kinson’s or Alzheimer’s disease or those recovering from a stroke.Methods In this paper,a complete framework that allows the construction of a 3D morphable shape model(3DMM)of the face is presented for fitting to a target RGB image.The model has the specific characteristic of being based on localized components of deformation.The fitting transformation is performed from 3D to 2D and guided by the correspondence between landmarks detected in the target image and those manually annotated on the average 3DMM.The fitting also has the distinction of being performed in two steps to disentangle face deformations related to the identity of the target subject from those induced by facial actions.Results The method was experimentally validated using the MICC-3D dataset,which includes 11 subjects.Each subject was imaged in one neutral pose and while performing 18 facial actions that deform the face in localized and asymmetric ways.For each acquisition,3DMM was fit to an RGB frame whereby,from the apex facial action and the neutral frame,the extent of the deformation was computed.The results indicate that the proposed approach can accurately capture face deformation,even localized and asymmetric deformations.Conclusion The proposed framework demonstrated that it is possible to measure deformations of a reconstructed 3D face model to monitor facial actions performed in response to a set of targets.Interestingly,these results were obtained using only RGB targets,without the need for 3D scans captured with costly devices.This paves the way for the use of the proposed tool in remote medical rehabilitation monitoring.展开更多
基金Supported by the National Natural Science Foundation of China(Grant No.12161013)the Basic Research Program(Natural Science)of Guizhou Province(Grant No.ZK[2023]025).
文摘In this paper,we call a tuple consisting of 3-Lie algebra and a higher derivation on it a 3-LieHDer pair.We introduce a cohomology theory of 3-LieHDer pairs.Next,we interpret the second cohomology group as the space of all isomorphism classes of abelian extensions.Finally,we consider formal deformations of 3-LieHDer pairs that are governed by the cohomology with self-coefficient.
基金National Natural Science Foundation of China(12161013)Research Projects of Guizhou University of Commerce in 2024。
文摘The modifiedλ-differential Lie-Yamaguti algebras are considered,in which a modifiedλ-differential Lie-Yamaguti algebra consisting of a Lie-Yamaguti algebra and a modifiedλ-differential operator.First we introduce the representation of modifiedλ-differential Lie-Yamaguti algebras.Furthermore,we establish the cohomology of a modifiedλ-differential Lie-Yamaguti algebra with coefficients in a representation.Finally,we investigate the one-parameter formal deformations and Abelian extensions of modifiedλ-differential Lie-Yamaguti algebras using the second cohomology group.
基金supported by the National Natural Science Foundation of China(Grant No.52090082).
文摘A holistic and precise assessment of retaining wall deformations is critical for on-site risk management of large combined deep excavation projects,where the risk-related points are highly dispersed,evolving,and interacting.Despite extensive exploration of this topic in previous studies,the omission of intricate spatiotemporal characteristics of wall deformations has resulted in diminished prediction accuracy and stability.To mitigate this deficiency,a spatiotemporal characteristics matrix for all data points and time series was first generated for a deep excavation scenario and used as input for a new hybrid model that combines convolutional neural network(CNN)and long short-term memory(LSTM)with incorporated attention mechanism(CNN-LSTM-Att),which enables the cross-learning mechanism and improves interpretability.In addition,by leveraging the attention weight,a new risk assessment index for retaining wall deformations across various scenarios was formulated.Then the proposed method was applied in a large combined deep excavation in Shanghai,China.The results show that:(1)The incorporation of fedin characteristic data and the attention mechanism enables the proposed method to produce satisfactory prediction results for the holistic spatiotemporal distribution of a large combined excavation;(2)Compared with other published models,the proposed model shows much better prediction accuracy,interpretability,and stability,especially in medium-and long-term predictions;and(3)The new risk assessment index serves as a reliable decision-making tool for assessing the risk evolution of retaining wall deformations and provides valuable guidance for effective risk management in multi-scenario excavation projects.
基金National Defense Foundation Scientific Research (B332006031-1)Youth Foundation of Shanxi Province (2008021030)Natural Science Foundation of Shanxi Province (2009011028-1)
文摘The influences of multiple plastic deformations on microstructure and mechanical properties of 7A04-T6 alloy by isothermal compression experiments in different passes deformation on the 6300 kN extrusion press. The experimental results showed that the strength and elongation of 7A04-T6 alloy were increased firstly and then decreased as the deformation pass increases at above 400 ℃. The grains of 7A04-T6 alloy was refined firstly and then grow, the grain was become refinement after four deformations under this experimental conditions. The second phase η (MgZn2) in the matrix would precipitate after solution, precipitation strengthening taking place. It is obvious that the number of second phase which dissolve into the matrix will increase as the deformation pass increasing. So the tensile strength reached the highest after four deformations, is 590.9 MPa, yield strength is 532.5 MPa, and elongation is 12.4%. After four deformations of 7A04-T6 alloy, tensile fracture surface of samples was composed of the deep and uniform dimples, belonging to ductile fracture. Therefore, 7A04-T6 alloy has better comprehensive mechanical properties after four deformations.
文摘This paper presents the results of numerical simulations carried out to confirm the influence of former mining activities on deformation of the mining terrain.The assessment of deformation changes was carried out with the use of FLAC3 D program based on the finite difference method.Numerical calculations were carried out for the example of actual mining operations in seams 703/1-2 and 707/2 of‘‘Marcel"Coal Mine.Taking into account the influence of the model’s plastic features and the so-called activation of a higher occurring seam in conducted simulations enabled obtaining a very good description of the measured subsidence.Based on the results one may state that numerical model can be used to assess the influence of former mining activities and the direction of conducted exploitation on deformations of the mining terrain.These factors are not recognized by geometric-integral theories commonly used for predicting the influence of mining operations on the surface.The results presented in this paper confirm that the applied method of simulating the phenomenon of reactivation of post-mining goafs is correct.
基金the National Natural Science Foundation of China(No.41604067,41974093,41331066,and 41774088)the Basic Research Fund of Chinese Academy of Surveying and Mapping(No.AR 1906)+1 种基金the special project of high-resolution Earth observation system(42-Y20A09-9001-17/18)the Key Research Program of Frontier Sciences Chinese Academy of Sciences(QYZDY-SSWSYS003).
文摘In this paper,we study how coseismic deformations calculated in 1066 Earth models are affected by how the models treat Earth discontinuities.From the results of applying models 1066A(continuous)and 1066B(discontinuous),we find that the difference in Love numbers of strike-slip and horizontal tensile sources are bigger than dip-slip and vertical tensile sources.Taken collectively,discontinuities have major effects on Green’s functions of four independent sources.For the near-field coseismic deformations of the 2013 Okhotsk earthquake(Mw 8.3),the overall differences between theoretical calculations in vertical displacement,geoid,and gravity changes caused by discontinuities are 10.52 percent,9.07 percent and 6.19 percent,with RMS errors of 0.624 mm,0.029 mm,and 0.063μGal,respectively.The difference in far-field displacements is small,compared with GPS data,and we can neglect this effect.For the shallow earthquake,2011 Tohoku-Oki earthquake(Mw 9.0),the differences in near-field displacements are 0.030 m(N-S),0.093 m(E-W),and 0.025 m(up-down)in our study area with the ARIA slip model,which gives results closer to GPS data than those from the USGS model.The difference in vertical displacements and gravity changes on the Earth’s surface caused by discontinuities are larger than 10 percent.The difference in the theoretical gravity changes at spatially fixed points truncated to degrees 60,as required by GRACE data,is 0.0016μGal and the discrepancy is 11 percent,with the theoretical spatial gravity changes from 1066B closer to observations than from 1066A.The results show that an Earth model with discontinuities in the medium has a large effect on the calculated coseismic deformations.
文摘This paper presents the results of a 2017 study conducted by the National Institute for Occupational Safety and Health(NIOSH), Pittsburgh Mining Research Division(PMRD), to evaluate the effects of longwall-induced subsurface deformations within a longwall abutment pillar under deep cover. The 2017 study was conducted in a southwestern Pennsylvania coal mine, which extracts 457 m-wide longwall panels under 361 m of cover. One 198 m-deep, in-place inclinometer monitoring well was drilled and installed over a 45 m by 84 m center abutment pillar. In addition to the monitoring well, surface subsidence measurements and underground coal pillar pressure measurements were conducted as the 457 m-wide longwall panel on the south side of the abutment pillar was being mined. Prior to the first longwall excavation, a number of simulations using FLAC3D^(TM) were conducted to estimate surface subsidence, increases in underground coal pillar pressure, and subsurface horizontal displacements in the monitoring well. Comparisons of the pre-mining FLAC3D simulation results and the surface, subsurface,and underground instrumentation results show that the measured in-place inclinometer casing deformations are in reasonable agreement with those predicted by the 3D finite difference models. The measured surface subsidence and pillar pressure are in excellent agreement with those predicted by the 3D models.Results from this 2017 research clearly indicate that, under deep cover, the measured horizontal displacements within the abutment pillar are approximately one order of magnitude smaller than those measured in a 2014 study under medium cover.
文摘Soil shear wave velocity has been recognized as a governing parameter in the assessment of the seismic response of slopes.The spatial variability of soil shear wave velocity can influence the seismic response of sliding mass and seismic displacements.However,most analyses of sliding mass response have been carried out by deterministic models.This paper stochastically investigates the effect of random heterogeneity of shear wave velocity of soil on the dynamic response of sliding mass using the correlation matrix decomposition method and Monte Carlo simulation(MCS).The software FLAC 7.0 along with a Matlab code has been utilized for this purpose.The influence of statistical parameters on the seismic response of sliding mass and seismic displacements in earth slopes with different inclinations and stiffnesses subject to various earthquake shakings was investigated.The results indicated that,in general,the random heterogeneity of soil shear modulus can have a notable impact on the sliding mass response and that neglecting this phenomenon could lead to underestimation of sliding deformations.
基金Supported by National Natural Science Foundation of China(Grant No.51272560)National Basic Research Program of China(973 Program,Grant No.2011CB302404)National Science Foundation for Distinguished Young Scholars of China(Grant No.51225503)
文摘Parallel kinematic machines have drawn considerable attention and have been widely used in some special fields.However,high precision is still one of the challenges when they are used for advanced machine tools.One of the main reasons is that the kinematic chains of parallel kinematic machines are composed of elongated links that can easily suffer deformations,especially at high speeds and under heavy loads.A 3-RRR parallel kinematic machine is taken as a study object for investigating its accuracy with the consideration of the deformations of its links during the motion process.Based on the dynamic model constructed by the Newton-Euler method,all the inertia loads and constraint forces of the links are computed and their deformations are derived.Then the kinematic errors of the machine are derived with the consideration of the deformations of the links.Through further derivation,the accuracy of the machine is given in a simple explicit expression,which will be helpful to increase the calculating speed.The accuracy of this machine when following a selected circle path is simulated.The influences of magnitude of the maximum acceleration and external loads on the running accuracy of the machine are investigated.The results show that the external loads will deteriorate the accuracy of the machine tremendously when their direction coincides with the direction of the worst stiffness of the machine.The proposed method provides a solution for predicting the running accuracy of the parallel kinematic machines and can also be used in their design optimization as well as selection of suitable running parameters.
基金Supported by the National Natural Science of China(Grant No.11761017)the Science and Technology Foundation of Guizhou Province(Grant No.[2020]1Y005)。
文摘In this paper,we introduce the representation and cohomology theory of Lie-Yamaguti color algebras.Furthermore,we introduce the notions of generalized derivations of Lie-Yamaguti color algebras and present some properties.Finally,we study linear deformations of LieYamaguti color algebras,and introduce the notion of a Nijenhuis operator on a Lie-Yamaguti color algebra,which can generate a trivial deformation.
基金funded by the directional earthquake tracking task offered by China Earthquake Administration (2017010203)the National Natural Science Foundation of China (No. 41274083)
文摘In this study, the relative gravity data(2012 e2015), GPS data-derived horizontal deformation(2011 e2014) and the background vertical deformation from the leveling measurements(1970 e2011) in the northeastern margin of Tibetan Plateau were processed to systematically analysis the mechanism of temporalespatial patterns and the relationship with Menyuan Ms6.4 earthquake. It can be summarized in the following: 1) The regional gravity changes, the GPS and the vertical deformational showed an intense spatial relationship: the gravity increased along with the direction of horizontal movement, and decreased with the crustal uplift and vice versa, which reflected the inherited characteristics of geotectonic activities. 2) The crustal deformations were closely related to the active faults. The contour lines of gravity changes and vertical deformation were generally along with the Qilian-Haiyuan fault(strike is NWW), and the crustal horizontal deformation showed left-lateral strike slip motion near the Qilian-Haiyuan fault. 3) Menyuan Ms6.4 earthquake occurred in the high negative gravity variation area and a high gradient formed in regions, positive and negative variation of gravity amount to 110 m Gal.Specifically, a borderline of positive and negative gravity located in the south of epicenter along the north edge of Qilianshan fault and Lenglongling fault, as well as the vertical and/or horizontal deformation is intensely. The extrusion deformation, surface compression rate and gravity changes were obvious near the epicenter of 2016 Menyuan Earthquake.
文摘Line heating process is a very complex phenomenon as a variety of factors affects the amount of residual deformations. Numerical thermal and mechanical analysis of line heating for prediction of residual deformation is time consuming. In the present work dimensional analysis has been presented to obtain a new relationship between input parameters and resulting residual deformations during line heating process. The temperature distribution and residual deformations for 6 mm, 8 mm, 10 mm and 12 mm thick steel plates were numerically estimated and compared with experimental and published results. Extensive data generated through a validated FE model were used to find co-relationship between the input parameters and the resulting residual deformation by multiple regression analysis. The results obtained from the deformation equations developed in this work compared well with those of the FE analysis with a drop in the computation time in the order of 100 (computational time required for FE analysis is around 7 200 second to 9 000 seconds and where the time required for getting the residual deformation by developed equations is only 60 to 90 seconds).
基金This research is supported by the National Basic Research Program of China(973 Program,Grant No.2014CB047100)the National Natural Science Foundation of China(Grant Nos.41472289,51179185 and 41807275).
文摘There are relatively few studies on large rotation or deformation by means of the three-dimensional(3D)numerical manifold method(NMM).A new modified symmetric and antisymmetric decomposition(MSAD)theory is developed and implemented into the 3D NMM,eliminating the false-volume expansion and false-rotation strain/stress problems.The Jaumann rate is used to measure the material rotation,and the geometric stiffness built on the Jaumann rate is deduced.The incremental formulas of the MSAD-based 3D NMM and a practical guide on the implementation of the MSAD theory are given in detail and exemplified.The new theory and formulas can be applied to analyze both large rotation and large deformation problems.Based on the hypoelasto-plasticity theory and the unified strength theory,the unified yield criterion with associated flow rule is implemented into the MSAD-based 3D NMM.Several typical examples are studied,showing the advantage and potential of the new MSAD theory and the MSAD-based 3D NMM.
文摘Objective To study the effect of changing heart rate on the ocular pulse and optic nerve head deformations with a viscoelastic lamina cribrosa.Methods An FE model of a healthy eye was reconstructed.The choroid was biphasic and consisted of a solid phase(connective tissues)and a fluid phase(blood).The LC was viscoelastic as characterized by a stress-relaxation test.We applied arterial pressures at 18 entry sites(posterior ciliary arteries)and venous pressures at 4 exit sites(vortex veins).The heart rate was varied from 60 bpm to 120 bpm(increment:20 bpm).We reported the ocular pulse amplitude(OPA),pulse volume,optic nerve head(ONH)deformations and the dynamic modulus of the LC at different heart rates.Results With an increasing heart rate,the OPA decreased by 0.04 mmHg for every 10 bpm increase.The pulse volume also exhibited a linear relationship with heart rate,and decreased by 0.13 L.In addition,the storage modulus and the loss modulus of the LC center increased by 0.014 MPa and 0.04 MPa,respectively for every 10 pm increase in heart rate.Conclusions Our model predicted that the OPA,the pulse volume the ONH deformation decreased at a faster heartrate.We also found that the viscoelastic LC became stiffer with an increasing heart rate.Further studies are required to explore the potential links with the vascular dysregulation and axonal loss in glaucoma.
基金funded by the National Natural Science Foundation of China (NO. 42104028, 42174030 and 42004017)the Project Supported by the Open Fund of Hubei Luojia Laboratory (Grant No. 220100048 and 230100021)Program for Hubei Provincial Science and Technology Innovation Talents (Grant No. 2022EJD010)
文摘Terrestrial water storage(TWs)variations are associated with water mass movements,which may cause the deformation displacements of the Global Navigation Satellite System(GNSS)stations.This study investigates the spatio-temporal Tws variations and addresses the relationship between deformation variations observed in the Huang-Huai-Hai River Basin(HHHRB)and local hydrological features.Results indicate that the vertical velocities at the GNSS stations induced by TWS changes are relatively small,and the impacts of the terrestrial water storage changes are mainly reflected in the changes of seasonal characteristics.Although there is a downward TWS trend from 2011 to 2022 in most HHHRB areas,velocities from the vertical displacements of both Gravity Recovery and Climate Experiment(GRACE)and GRACE Follow-On(GFO)and the GNSS reflect that the HHHRB is undergoing an uplift process,while the magnitude of the GRACE/GFO derived velocities is much smaller than that of the GNSS solutions.Common hydrological deformations estimated from GRACE/GFO and GNSS measurements reveal that the TWS-derived displacements can explain 54.5%of the GNSS seasonal variations,with the phases of terrestrial water storage advancing by about one month relative to GNss common signal phases.Moreover,the decrease of the groundwater storage in the HHHRB has been accelerating since 2008.After reaching its lowest level around mid-2020,it began to rise rapidly,which might be closely related to the implementation of the South-North Water Transfer Central Project.
基金Project supported by the National Natural Science Foundation of China(Nos.10572119,10632030 and 50625516)the Program for New Century Excellent Talents in University(No.NCET-04-0958)+1 种基金the Major State Basic Research Development Program of China(973 Program)(No.2003CB716207)the Open Foundation of State Key Laboratory of Structural Analysis of Industrial Equipment of China
文摘Based on Hamilton＇s principle, a new kind of fully coupled nonlinear dynamic model for a rotating rigid-flexible smart structure with a tip mass is proposed. The geometrically nonlinear effects of the axial, transverse displacement and rotation angle are considered by means of the first-order approximation coupling （FOAC） model theory, in which large deformations and the centrifugal stiffening effects are considered. Three kinds of systems are established respectively, which are a structure without piezoelectric layer, with piezoelectric layer in open circuit and closed circuit. Several simulations based on simplified models are presented to show the differences in characteristics between structures with and without the tip mass, between smart beams in closed and open circuit, and between the centrifugal effects in high speed rotating state or not. The last simulation calculates the dynamic response of the structure subjected to external electrical loading.
文摘Experimental crystallographic structural parameters of a range of metaled meso-substituted and unsubstituted porphyrins were reviewed to show how far the meso-substitution by any functional group and the insertion of metal in the porphyrins core macrocycle may affect the geometry. The analysis of twists and angles has shown two kinds of distortions: external [T(C<sup>β</sup>-C<sup>α</sup>-C<sup>meso</sup>-X<sup>n</sup>) and T(C<sup>β</sup>-C<sup>α</sup>-C<sup>meso</sup>-C<sup>α</sup>)] and internal [T(N<sup>m</sup>-C<sup>α</sup>-C<sup>meso</sup>-X<sup>n</sup>) and T(N<sup>n</sup>-C<sup>α</sup>-C<sup>meso</sup>-C<sup>α</sup>)] with averages of [+6°and –6°] and [–5°and +5°], respectively. In the meso-substituted case, the external and internal twists C<sup>β</sup>-C<sup>α</sup>-C<sup>meso</sup>-X and N-C<sup>α</sup>-C<sup>meso</sup>-X, respectively are oppositely orientated. Similar effect is observed in meso-unsubstituted of C<sup>β</sup>-C<sup>α</sup>- C<sup>meso</sup>-H and N-C<sup>α</sup>-C<sup>meso</sup>-H. However, the external distortions are more significant than internal. Considering the same order, the limit of distortions is [97°and 132°(–48°)] for external and [91°(–89°) and 52°] for internal. In the two cases, the substituents have opposite directions of distortions. The meso-substituted porphyrins have a high limit of twisting than usubstituted one, depending of the weight of substituents. The average of the bond angular deformations is 168°, almost planar. However, the limit of angular deformation is 94°.
基金Supported by the Research Work of Liaoning Provincial Development of Education under Grant No.L2010513
文摘We propose a method to construct the integrable Rosochatius deformations for an integrable couplingsequations hierarchy.As applications, the integrable Rosochatius deformations of the coupled CKdV hierarchy withself-consistent sources and its Lax representation are presented.
文摘Background The accurate(quantitative)analysis of 3D face deformation is a problem of increasing interest in many applications.In particular,defining a 3D model of the face deformation into a 2D target image to capture local and asymmetric deformations remains a challenge in existing literature.A measure of such local deformations may be a relevant index for monitoring the rehabilitation exercises of patients suffering from Par-kinson’s or Alzheimer’s disease or those recovering from a stroke.Methods In this paper,a complete framework that allows the construction of a 3D morphable shape model(3DMM)of the face is presented for fitting to a target RGB image.The model has the specific characteristic of being based on localized components of deformation.The fitting transformation is performed from 3D to 2D and guided by the correspondence between landmarks detected in the target image and those manually annotated on the average 3DMM.The fitting also has the distinction of being performed in two steps to disentangle face deformations related to the identity of the target subject from those induced by facial actions.Results The method was experimentally validated using the MICC-3D dataset,which includes 11 subjects.Each subject was imaged in one neutral pose and while performing 18 facial actions that deform the face in localized and asymmetric ways.For each acquisition,3DMM was fit to an RGB frame whereby,from the apex facial action and the neutral frame,the extent of the deformation was computed.The results indicate that the proposed approach can accurately capture face deformation,even localized and asymmetric deformations.Conclusion The proposed framework demonstrated that it is possible to measure deformations of a reconstructed 3D face model to monitor facial actions performed in response to a set of targets.Interestingly,these results were obtained using only RGB targets,without the need for 3D scans captured with costly devices.This paves the way for the use of the proposed tool in remote medical rehabilitation monitoring.
