FEMUR SHAPE RECOVERY FROM VOLUMETRIC IMAGES USING 3-D DEFORMABLE MODELS

A new scheme for femur shape recovery from volumetric images using deformable models was proposed. First, prior 3 D deformable femur models are created as templates using point distribution models technology. Second, active contour models are employed to segment the magnetic resonance imaging (MRI) volumetric images of the tibial and femoral joints and the deformable models are initialized based on the segmentation results. Finally, the objective function is minimized to give the optimal results constraining the surface of shapes.

Analytical model for predicting time-dependent lateral deformation of geosynthetics-reinforced soil walls with modular block facing

To date,few models are available in the literature to consider the creep behavior of geosynthetics when predicting the lateral deformation(d)of geosynthetics-reinforced soil(GRS)retaining walls.In this study,a general hyperbolic creep model was first introduced to describe the long-term deformation of geosynthetics,which is a function of elapsed time and two empirical parameters a and b.The conventional creep tests with three different tensile loads(Pr)were conducted on two uniaxial geogrids to determine their creep behavior,as well as the a-Pr and b-Pr relationships.The test results show that increasing Pr accelerates the development of creep deformation for both geogrids.Meanwhile,a and b respectively show exponential and negatively linear relationships with Pr,which were confirmed by abundant experimental data available in other studies.Based on the above creep model and relationships,an accurate and reliable analytical model was then proposed for predicting the time-dependent d of GRS walls with modular block facing,which was further validated using a relevant numerical investigation from the previous literature.Performance evaluation and comparison of the proposed model with six available prediction models were performed.Then a parametric study was carried out to evaluate the effects of wall height,vertical spacing of geogrids,unit weight and internal friction angle of backfills,and factor of safety against pullout on d at the end of construction and 5 years afterwards.The findings show that the creep effect not only promotes d but also raises the elevation of the maximum d along the wall height.Finally,the limitations and application prospects of the proposed model were discussed and analyzed.

Flow behavior of Al-6.2Zn-0.70Mg-0.30Mn-0.17Zr alloy during hot compressive deformation based on Arrhenius and ANN models

The hot deformation behavior of Al?6.2Zn?0.70Mg?0.30Mn?0.17Zr alloy was investigated by isothermal compressiontest on a Gleeble?3500machine in the deformation temperature range between623and773K and the strain rate range between0.01and20s?1.The results show that the flow stress decreases with decreasing strain rate and increasing deformation temperature.Basedon the experimental results,Arrhenius constitutive equations and artificial neural network(ANN)model were established toinvestigate the flow behavior of the alloy.The calculated results show that the influence of strain on material constants can berepresented by a6th-order polynomial function.The ANN model with16neurons in hidden layer possesses perfect performanceprediction of the flow stress.The predictabilities of the two established models are different.The errors of results calculated by ANNmodel were more centralized and the mean absolute error corresponding to Arrhenius constitutive equations and ANN model are3.49%and1.03%,respectively.In predicting the flow stress of experimental aluminum alloy,the ANN model has a betterpredictability and greater efficiency than Arrhenius constitutive equations.

Prediction on hot deformation behavior of spray-formed 7055 aluminum alloy via phenomenological models

Hot compression tests in the temperature range of 340-450 ℃ and strain rate range of 0.001-1 s^-1 of spray-formed 7055 aluminum alloy were carried out to study its hot deformation behavior. Three phenomenological models including Johnson-Cook, modified Fields-Backofen and Arrhenius-type were introduced to predict the flow stresses during the compression process. And then, a comparative predictability of the phenomenological models was estimated in terms of the relative errors, correlation coefficient（R）, and average absolute relative error（AARE）. The results indicate that Johnson-Cook model and modified Fields-Backofen model cannot well predict the hot deformation behavior due to the large deviation in the process of line regression fitting. Arrhenius-type model obtains the best fit through combining the effect of strain rate and temperature.

Using multi-matching system based on a simplified deformable model of the human iris for iris recognition

A new method for iris recognition using a multi-matching system based on a simplified deformable model of the human iris was proposed. The method defined iris feature points and formed the feature space based on a wavelet transform. In the matching stage it worked in a crude manner. Driven by a simplified deformable iris model, the crude matching was refined. By means of such multi-matching system, the task of iris recognition was accomplished. This process can preserve the elastic deformation between an input iris image and a template and improve precision for iris recognition. The experimental results indicate the va- lidity of this method.

Treatment of discontinuities inside Earth models:Effects on computed coseismic deformations

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.

An improved strain-softening constitutive model of granite considering the effect of crack deformation

This paper presents an improved strain-softening constitutive model considering the effect of crack deformation based on the triaxial cyclic loading and unloading test results.The improved model assumes that total strain is a combination of plastic,elastic,and crack strains.The constitutive relationship between the crack strain and the stress was further derived.The evolutions of mechanical parameters,i.e.strength parameters,dilation angle,unloading elastic modulus,and deformation parameters of crack,with the plastic strain and confining pressure were studied.With the increase in plastic strain,the cohesion,friction angle,dilation angle,and crack Poisson's ratio initially increase and subsequently decrease,and the unloading elastic modulus and the crack elastic modulus nonlinearly decrease.The increasing confining pressure enhances the strength and unloading elastic modulus,and decreases the dilation angle and Poisson's ratio of the crack.The theoretical triaxial compressive stress-strain curves were compared with the experimental results,and they present a good agreement with each other.The improved constitutive model can well reflect the nonlinear mechanical behavior of granite.

αDecay in extreme laser fields within a deformed Gamow-like model

In this study, the effect of extreme laser fields on the α decay process of ground-state even–even nuclei was investigated.Using the deformed Gamow-like model, we found that state-of-the-art lasers can cause a slight change in the α decay penetration probability of most nuclei. In addition, we studied the correlation between the rate of change of the α decay penetration probability and angle between the directions of the laser electric field and α particle emission for different nuclei. Based on this correlation, the average effect of extreme laser fields on the half-life of many nuclei with arbitrary α particle emission angles was calculated. The calculations show that the laser suppression and promotion effects on the α decay penetration probability of the nuclei population with completely random α particle-emission directions are not completely canceled.The remainder led to a change in the average penetration probability of the nuclei. Furthermore, the possibility of achieving a higher average rate of change by altering the spatial shape of the laser is explored. We conclude that circularly polarized lasers may be helpful in future experiments to achieve a more significant average rate of change of the α decay half-life of the nuclei population.

Characterizing permeability-porosity relationships of porous rocks using a stress sensitivity model in consideration of elastic-structural deformation and tortuosity sensitivity

Clarifying the relationship between stress sensitivities of permeability and porosity is of great significance in guiding underground resource mining.More and more studies focus on how to construct stress sensitivity models to describe the relationship and obtain a comprehensive stress sensitivity of porous rock.However,the limitations of elastic deformation calculation and incompleteness of considered tortuosity sensitivity lead to the fact that the existing stress sensitivity models are still unsatisfactory in terms of accuracy and generalization.Therefore,a more accurate and generic stress sensitivity model considering elastic-structural deformation of capillary cross-section and tortuosity sensitivity is proposed in this paper.The elastic deformation is derived from the fractal scaling model and Hooke's law.Considering the effects of elastic-structural deformation on tortuosity sensitivity,an empirical formula is proposed,and the conditions for its applicability are clarified.The predictive performance of the proposed model for the permeability-porosity relationships is validated in several sets of publicly available experimental data.These experimental data are from different rocks under different pressure cycles.The mean and standard deviation of relative errors of predicted stress sensitivity with respect to experimental data are 2.63%and 1.91%.Compared with other models,the proposed model has higher accuracy and better predictive generalization performance.It is also found that the porosity sensitivity exponent a,which can describe permeability-porosity relationships,is 2 when only elastic deformation is considered.a decreases from 2 when structural deformation is also considered.In addition,a may be greater than 3 due to the increase in tortuosity sensitivity when tortuosity sensitivity is considered even if the rock is not fractured.

Rainfall-triggered waste dump instability analysis based on surface 3D deformation in physical model test

Landslide is the second largest natural disaster after earthquake. It is of significance to study the evolution laws and failure mechanism of landslides based on its surface 3D deformation information. Based on the rainfall-triggered waste dump instability model test, we studied the failure mechanisms of the waste dump by integrating surface deformation and internal slope stress and proposed novel parameters for identifying landslide stability. We developed a noncontact measurement device, which can obtain millimeter-level 3D deformation data for surface scene in physical model test;Then we developed the similar materials and established a test model for a waste dump. Based on the failure characteristics of slope surface, internal stress of slope body and displacement contours during the whole process, we divided the slope instability process in model test into four stages: rainfall infiltration and surface erosion, shallow sliding, deep sliding, and overall instability. Based on the obtained surface deformation data, we calculated the volume change during slope instability process and compared it with the point displacement on slope surface. The results showed that the volume change can not only reflect the slow-ultra acceleration process of slope failure, but also fully reflect the above four stages and reduce the fluctuations caused by random factors. Finally, this paper proposed two stability identification parameters: the volume change rate above the slip surface and the relative velocity of volume change rate. According to the calculation of these two parameters in model test, they can be used for study the deformation and failure mechanism of slope stability.

Comparative Study on Deformation Prediction Models of Wuqiangxi Concrete Gravity Dam Based on Monitoring Data

The deformation prediction models of Wuqiangxi concrete gravity dam are developed,including two statistical models and a deep learning model.In the statistical models,the reliable monitoring data are firstly determined with Lahitte criterion;then,the stepwise regression and partial least squares regression models for deformation prediction of concrete gravity dam are constructed in terms of the reliable monitoring data,and the factors of water pressure,temperature and time effect are considered in the models;finally,according to the monitoring data from 2006 to 2020 of five typical measuring points including J23(on dam section 24^(#)),J33(on dam section 4^(#)),J35(on dam section 8^(#)),J37(on dam section 12^(#)),and J39(on dam section 15^(#))located on the crest of Wuqiangxi concrete gravity dam,the settlement curves of the measuring points are obtained with the stepwise regression and partial least squares regression models.A deep learning model is developed based on long short-term memory(LSTM)recurrent neural network.In the LSTM model,two LSTMlayers are used,the rectified linear unit function is adopted as the activation function,the input sequence length is 20,and the random search is adopted.The monitoring data for the five typical measuring points from 2006 to 2017 are selected as the training set,and the monitoring data from 2018 to 2020 are taken as the test set.From the results of case study,we can find that(1)the good fitting results can be obtained with the two statistical models;(2)the partial least squares regression algorithm can solve the model with high correlation factors and reasonably explain the factors;(3)the prediction accuracy of the LSTM model increases with increasing the amount of training data.In the deformation prediction of concrete gravity dam,the LSTM model is suggested when there are sufficient training data,while the partial least squares regression method is suggested when the training data are insufficient.

A NEW DEFORMABLE MODEL USING LEVEL SETS FOR SHAPE SEGMENTATION

In this paper, we present a new deformable model for shape segmentation, which makes two modifications to the original level set implementation of deformable models.The modifications are motivated by difficulties that we have encountered in applying deformable models to segmentation of medical images.The level set algorithm has some advantages over the classical snake deformable models.However, it could develop large gaps in the boundary and holes within the objects.Such boundary gaps and holes of objects can cause inaccurate segmentation that requires manual correction.The proposed method in this paper possesses an inherent property to detect gaps and holes within the object with a single initial contour and also does not require specific initialization.The first modification is to replace the edge detector by some area constraint, and the second modification utilizes weighted length constraint to regularize the curve under evolution.The proposed method has been applied to both synthetic and real images with promising results.

On well-posedness of two-phase nonlocal integral models for higher-order refined shear deformation beams

Due to the conflict between equilibrium and constitutive requirements,Eringen’s strain-driven nonlocal integral model is not applicable to nanostructures of engineering interest.As an alternative,the stress-driven model has been recently developed.In this paper,for higher-order shear deformation beams,the ill-posed issue(i.e.,excessive mandatory boundary conditions(BCs)cannot be met simultaneously)exists not only in strain-driven nonlocal models but also in stress-driven ones.The well-posedness of both the strain-and stress-driven two-phase nonlocal(TPN-Strain D and TPN-Stress D)models is pertinently evidenced by formulating the static bending of curved beams made of functionally graded(FG)materials.The two-phase nonlocal integral constitutive relation is equivalent to a differential law equipped with two restriction conditions.By using the generalized differential quadrature method(GDQM),the coupling governing equations are solved numerically.The results show that the two-phase models can predict consistent scale-effects under different supported and loading conditions.

Several Typical Geomechanical Models of Deformation Fracture of Mountain in High Earthquake Intensity Area

The deformation fracture and stability of mountain under the earthquake action is an important issue that arouses concern of researchers in the field of engineering geology.The authors,from 2000 to 2006, selected the 1933 earthquake in Diexi zone as a typical study site to carry out the genetic mechanism research of mountain deformation-fracture caused by earthquake; in order to have comparability,the breadth

ANALYTICAL MODEL OF CERAMIC/METAL ARMOR IMPACTED BY DEFORMABLE PROJECTILE

A new analytical model was established to describe the complex behavior of ceramic/metal armor under impact of deformable projectile by assuming some hypotheses. Three aspects were taken into account： the mushrooming deformation of the projectile, the fragment of ceramic tile and the formation and change of ceramic conoid and the deformation of the metal backup plate. Solving the set of equations, all the variables were obtained for the different impact velocities： the extent and particle velocity in rigid zone; the extent, cross-section area and particle velocity in plastic zone; the velocity and depth of penetration of projectile to the target; the reduction in volume and compressive strength of the fractured ceramic conoid; the displacement and movement velocity of the effective zone of backup plate. Agreement observed among analytical result, numerical simulation and experimental result confirms the validity of the model, suggesting the model developed can be a useful tool for ceramic/metal armor design.

Static Force-Based Modeling and Parameter Estimation for a Deformable Link Composed of Passive Spherical Joints With Preload Forces

To balance the contradiction between higher flexibility and heavier load bearing capacity,we present a novel deformable manipulator which is composed of active rigid joints and deformable links.The deformable link is composed of passive spherical joints with preload forces between socket-ball surfaces.To estimate the load bearing capacity of a deformable link,we present a static force-based model of spherical joint with preload force and analyze the static force propagation in the deformable link.This yields an important result that the load bearing capacity of a spherical joint only depends on its radius,preload force,and static friction coefficient.We further develop a parameter estimation method to estimate the product of preload force and static friction coefficient.The experimental results validate our model.80.4%of percentage errors on the maximum payload mass prediction are below 15%.

4-Dimensional Models of Deformation of the Earth's Crust and Earthquake Prediction

Traditionally, when creating 4-D models of elastic offsets in the Earth’s crust, the data from geodesic and GPS monitoring of offsets on the ground surface, earthquake catalogs, monitoring of the water level and radon content in wells, sea level fluctuations, as well as gravitational and magnetic fields, etc., can be taken as bases for information. In essence, the reason for creating a 4-D model of slow elastic deformations is to approximate the process by a set of plane deformation solitons (solitary waves). The parameters of a set of deformation solitons are obtained by a two-stage inversion. First, the parameters of the model are determined in a kinematic way by the use of a modified simplification of the method. Then, a calibration of the amplitude characteristics of the model is carried out in terms of elastic dynamic offsets. Taking Ural, Northern Tianshan, Greece, and China as examples, models for these regions are created on the basis of seismological, geodesic, deformation, hydrogeological,

Deformable DETR大模型在新农业的应用研究——以宁夏固原娃娃菜病虫害检测与识别为例

宁夏固原市露地娃娃菜种植规模逐年增加,市场需求广泛,促进了农村经济的发展。但传统的娃娃菜病虫害检测方法由于耗时长、效率低、成本高,已不能满足快速发展农业生产的需要。文中以固原市农科院露地娃娃菜为研究对象,基于Deformable DETR模型对霜霉病、软腐病、菜青虫3种主要病虫害进行检测与识别,不仅提高了病虫害检测的效率和准确性,且降低了管理成本,有助于固原市农业生产者实现更加高效、科学的病虫害防治。

Generalized functional model of maximum and minimum detectable deformation gradient for PALSAR interferometry

Empirical functional models for the maximum and minimum detectable deformation gradient of PALSAR interferometry were established based on coherence and discrete look numbers. Then, a least square regression method was used to fit the model coefficients and thus obtain the generalized functional models for both coherence and look numbers. The experimental results with ALOS PALSAR data of Wenchuan earthquake of China show that the new model works well for judging whether the deformation gradient can be detected by the D-InSAR technology or not. The results can help researchers to choose PALSAR data and to configure processing parameters, and also benefit the interpretation of the measured surface deformation.