In the past decades, the necessity for detailed earthquake microzonation studies was recognized worldwide. Therefore, different approaches were established and applied. Unfortunately, the majority of these approaches ...In the past decades, the necessity for detailed earthquake microzonation studies was recognized worldwide. Therefore, different approaches were established and applied. Unfortunately, the majority of these approaches are not based on pre-existing field data but require extensive seismic measurements and investigations. Furthermore, these approaches incorporate non-linearity inadequately and cannot take groundwater level changes into account. For this purpose, notably numerical models are most suitable. These models require a good knowledge of the local geological conditions （especially of the uppermost unconsolidated units）, information about the geotechnical parameters of these units, and a hydrogeological model of the investigated area. Most of this information can be obtained from geotechnical investigations and surveys that have already been carried out in most densely populated areas. In a case study for Bucharest City, non-linear analyses were performed using software that is based on the visco-hypoplastic constitutive law. The results indicate that groundwater level changes have an important influence on duration and amplitude of ground response and thus should be considered for seismic microzonation studies. This approach ean be used to display site effects and to identify different microzones taking different earthquake magnitudes and groundwater levels into account.展开更多
CeO2/TiO2 composite nanoparticles with different Ce/Ti molar ratios have been successfully synthesized via sol-gel method. It was found that the band gap of the nanocomposite is tunable by varying Ce/Ti content. The n...CeO2/TiO2 composite nanoparticles with different Ce/Ti molar ratios have been successfully synthesized via sol-gel method. It was found that the band gap of the nanocomposite is tunable by varying Ce/Ti content. The nonlinear response of the sample was studied by using the nanosecond laser pulses from a Q switched Nd：Yag laser employing the Z-scan method. Open aperture Z-scan experiment revealed that with the increase in the CeO2 amount in the nanocomposite, the non-linearity of the composite increases, and it was assumed that this could be due to the modification of TiO2 dipole symmetry by the addition of CeO2. Closed aperture Z-scan experiment showed that when the CeO2 amount increases, positive nonlinear refraction decreases, and this could be attributed to the increase in the two photon absorption which subsequently suppresses the nonlinear refraction.展开更多
A gyro-stabilizer is the interesting system that it can apply to marine vessels for diminishes roll motion.Today it has potentially light weight with no hydrodynamics drag and effective at zero forward speed.The...A gyro-stabilizer is the interesting system that it can apply to marine vessels for diminishes roll motion.Today it has potentially light weight with no hydrodynamics drag and effective at zero forward speed.The twin-gyroscope was chosen.Almost,the modelling for designing the system use linear model that it might not comprehensive mission requirement such as high sea condition.The non-linearity analysis was proved by comparison the results between linear and non-linear model of gyro-stabilizer throughout frequency domain also same wave input,constrains and limitations.Moreover,they were cross checked by simulating in time domain.The comparison of interested of linear and non-linear close loop model in frequency domain has demonstrated the similar characteristics but gave different values at same frequency obviously.The results were confirmed again by simulation in irregular beam sea on time domain and they demonstrate the difference of behavior of both systems while the gyro-stabilizers are switching on and off.From the resulting analysis,the non-linear gyro-stabilizer model gives more real results that correspond to more accuracy in a designing gyro-stabilizer control system for various amplitudes and frequencies operating condition especially high sea condition.展开更多
Electrochemical impedance spectroscopy,a method for battery diagnostics,is used to estimate the internal temperature of a lithium-ion battery cell during highly dynamic load profiles.For the first time,a recurrent neu...Electrochemical impedance spectroscopy,a method for battery diagnostics,is used to estimate the internal temperature of a lithium-ion battery cell during highly dynamic load profiles.For the first time,a recurrent neural network is trained and evaluated with operando impedance data for temperature estimation.Furthermore,an approach is considered that guides the training process of the neural network by incorporating physical constraints.The model’s development based on an extensive series of measurements with different load profiles,tested under realistic conditions on large-format lithium-ion cells.The estimation accuracy of the data-driven approach is evaluated and compared against model-based methods,including the extended Kalman filter.An impedance correction model is proposed,which leads to a significant enhancement of the model-based estimation.The recurrent neural network under consideration achieves a mean square error of 1.07℃ for the investigated testing profiles in the temperature range up to 60℃.展开更多
The Proper Orthogonal Decomposition(POD)-based ensemble four-dimensional variational(4DVar) assimilation method(POD4DEnVar) was proposed to combine the strengths of EnKF(i.e.,the ensemble Kalman filter) and 4DVar assi...The Proper Orthogonal Decomposition(POD)-based ensemble four-dimensional variational(4DVar) assimilation method(POD4DEnVar) was proposed to combine the strengths of EnKF(i.e.,the ensemble Kalman filter) and 4DVar assimilation methods.Recently,a POD4DEnVar-based radar data assimilation scheme(PRAS) was built and its effectiveness was demonstrated.POD4 DEnVar is based on the assumption of a linear relationship between the model perturbations(MPs)and the observation perturbations(OPs);however,this assumption is likely to be destroyed by the highly non-linear forecast model or observation operator.To address this issue,using the Gauss-Newton iterative method,the nonlinear least squares enhanced POD4 DEnVar algorithm(referred to as NLS-4DVar) was proposed.Naturally,the PRAS was upgraded to form the NLS-4DVar-based radar data assimilation scheme(NRAS).To evaluate the performance of NRAS against PRAS,observing system simulation experiments(OSSEs) were conducted to assimilate reflectivity and radial velocity individually,with one,two,and three iterations.The results demonstrated that the NRAS outperformed PRAS in improving the initial condition and the forecasting of model variables and rainfall.The NRAS,with a smaller number of iterations,can yield a convergent result.In contrast to the situation when assimilating radial velocity,the advantages of NRAS over PRAS were more obvious when assimilating reflectivity.展开更多
Many experiments have supported the contact models,such as the GW and MB models,but the majority of previous validations have been performed under light loads,resulting in a linear relationship between normal force an...Many experiments have supported the contact models,such as the GW and MB models,but the majority of previous validations have been performed under light loads,resulting in a linear relationship between normal force and contact area.However,the real contact area fraction should never equal one;there must be a limit smaller than the apparent area,implying that the real contact area cannot increase linearly indefinitely.In this paper,the real contact area between two polymethylmethacrylate(PMMA)blocks under heavy load is measured using the total reflection method,and the contact area is analyzed using the image processing method.The results show that the real contact area increases with normal load linearly in light loads but non-linearly in heavy loads;the number of contact spots increases with load linearly in light loads but also non-linearly in heavy loads,synchronous with the change in the real contact area.The GW,MB,and Zhao,Maietta,and Chang(ZMC)models were used to predict the experiment results,but none of them predicted the non-linear stage.A revised GW model based on the bulk deformation hypothesis performs better in predicting the non-linear stage.The study’s findings can be applied to PMMA or other similar materials,and they can serve as a useful reference for future research on the contact mechanisms of other materials.展开更多
Organisms have evolved a strain limiting mechanism,reflected as a non-linear elastic constitutive,to prevent large deformations from threatening soft tissue integrity.Compared with linear elastic substrates,the wrinkl...Organisms have evolved a strain limiting mechanism,reflected as a non-linear elastic constitutive,to prevent large deformations from threatening soft tissue integrity.Compared with linear elastic substrates,the wrinkle of films on non-linear elastic substrates has received less attention.In this article,a unique wrinkle evolution of the film-substrate system with a J-shaped non-linear stress-strain relation is reported.The result shows that a concave hexagonal array pattern is formed with the shrinkage strain of the film-substrate systems developing.As the interconnection of hexagonal arrays,a unit cell ridge network appears with properties such as chirality and helix.The subparagraph maze pattern formed with high compression is mainly composed of special single-cell ridge networks such as spiral single cores,chiral double cores,and combined multi-cores.This evolutionary model is highly consistent with the results of experiments,and it also predicts wrinkle morphology that has not yet been reported.These findings can serve as a novel explanation for the surface wrinkle of biological soft tissue,as well as provide references for the preparation of artificial biomaterials and programmable soft matter.展开更多
This opinion article discusses the original research work of Yünkül et al.(the Authors)published in the Journal of Mountain Science 21(9):3108–3122.Employing non-linear regression,fuzzy logic and artificial...This opinion article discusses the original research work of Yünkül et al.(the Authors)published in the Journal of Mountain Science 21(9):3108–3122.Employing non-linear regression,fuzzy logic and artificial neural network modeling techniques,the Authors interrogated a large database assembled from the existing research literature to assess the performance of twelve equation rules in predicting the undrained shear strength(s_(u))mobilized for remolded fine-grained soils at different values of liquidity index(I_(L))and water content ratio.Based on their analyses,the Authors proposed a simple and reportedly reliable correlation(i.e.,Eq.9 in their paper)for predicting s_(u) over the I_(L) range of 0.15 to 3.00.This article describes various shortcomings in the Authors’assembled database(including potentially anomalous data and covering an excessively wide I_(L) range in relation to routine geotechnical and transportation engineering applications)and their proposed s_(u)=f(I_(L))correlation.Contrary to the Authors’assertions,their proposed correlation is not reliable for fine-grained soils with consistencies in the general firm to stiff range(i.e.,for 0.15<I_(L)<0.40),increasingly overestimating s_(u) for reducing I_(L),and eventually predicting s_(u)→+∞for I_(L)→0.15+(while producing mathematically undefined s_(u) for I_(L)<0.15),thus rendering their correlation unconservative and potentially leading to unsafe geotechnical designs.Exponential or regular-power type s_(u)=f(I_(L))models are more s_(u)itable when developing correlations that are applicable over the full plastic range(of 0<I_(L)<1),thereby providing reasonably conservative s_(u) predictions for use in the preliminary design for routine geotechnical engineering applications.展开更多
Wavelet transforms have been successfully used in seismic data processing with their ability for local time - frequency analysis. However, identification of directionality is limited because wavelet transform coeffici...Wavelet transforms have been successfully used in seismic data processing with their ability for local time - frequency analysis. However, identification of directionality is limited because wavelet transform coefficients reveal only three spatial orientations. Whereas the ridgelet transform has a superior capability for direction detection and the ability to process signals with linearly changing characteristics. In this paper, we present the issue of low signal-to-noise ratio （SNR） seismic data processing based on the ridgelet transform. Actual seismic data with low SNR from south China has been processed using ridgelet transforms to improve the SNR and the continuity of seismic events. The results show that the ridgelet transform is better than the wavelet transform for these tasks.展开更多
The microstructure evolution and properties of an Al-Zn-Mg-Cu alloy were investigated under different non-linear cooling processes from the solution temperature, combined with in-situ electrical resistivity measuremen...The microstructure evolution and properties of an Al-Zn-Mg-Cu alloy were investigated under different non-linear cooling processes from the solution temperature, combined with in-situ electrical resistivity measurements, selected area diffraction patterns （SADPs）, transmission electron microscopy （TEM）, and tensile tests. The relative resistivity was calculated to characterize the phase transformation of the experimental alloy during different cooling processes. The results show that at high temperatures, the microstructure evolutions change from the directional diffusion of Zn and Mg atoms to the precipitation of S phase, depending on the cooling rate. At medium temperatures, q phase nucleates on A13Zr dispersoids and grain boundaries under fast cooling conditions, while S phase precipitates under the slow cooling conditions. The strength and ductility of the aged alloy suffer a significant deterioration due to the heterogeneous precipitation in medium temperature range. At low temperatures, homogeneously nucleated GP zone, η′ and η phases precipitate.展开更多
In this paper, the characteristics of different forms of mild slope equations for non-linear wave are analyzed, and new non-linear theoretic models for wave propagation are presented, with non-linear terms added to th...In this paper, the characteristics of different forms of mild slope equations for non-linear wave are analyzed, and new non-linear theoretic models for wave propagation are presented, with non-linear terms added to the mild slope equations for non-stationary linear waves and dissipative effects considered. Numerical simulation models are developed of non-linear wave propagation for waters of mildly varying topography with complicated boundary, and the effects are studied of different non-linear corrections on calculation results of extended mild slope equations. Systematical numerical simulation tests show that the present models can effectively reflect non-linear effects.展开更多
Numerical experiments on non-linear equations of the 1st-and 3rd-order derivatives have been carried out through structural analyses in the phase space according to the numerical instability of ill-posed systems,with ...Numerical experiments on non-linear equations of the 1st-and 3rd-order derivatives have been carried out through structural analyses in the phase space according to the numerical instability of ill-posed systems,with changes of initial values and parameters,etc..The results show that the quantitative instability in an ill-posed system may reveal reversed transformation in system evolution by structural representation,and confirm A·Dauglas' theorem that "a non-linear equation does not satisfy the existence of the initial value in a linear well-posed system".展开更多
Orwell＇s text The Road to Wigan Pier, henceforth referred to as RWP, is problematic due to the ambiguity of its status as a literary genre. The text is subversive on many levels, namely on the level of form. In order...Orwell＇s text The Road to Wigan Pier, henceforth referred to as RWP, is problematic due to the ambiguity of its status as a literary genre. The text is subversive on many levels, namely on the level of form. In order to show some aspects of the author＇s challenge of the conventional norms and methods of literary writing, a comparison between the writer＇s original diary of the journey to the industrial North of England, the main site of the coal mines, and the present book could be of great import. This reveals the author＇s genuine intellectual ability to manipulate and rearrange the events and scenes of the story on the discourse level. The author＇s manipulation and rearrangement of the story （the journey）, events and scenes, clearly reveals his potential literary creativity and imagination. Orwell has deployed many strategies to fulfil this purpose. Each strategy is actually a contribution to the author＇s overall argument and at the same time it constitutes a further aspect of subversion. The first aspect of subversion lies on the level of form itself. The form of the book is effectively very challenging. Contrary to the conventional view of the fictional novel, the study of Orwell＇s text based on Grrard Genette＇s model reveals his challenge of the basic novelistic parameters. The novelistic ingredients such as setting, characterisation, and plot development have been treated in a subverting way. Though not totally discarded, they have been manipulated for the purpose of the author＇s general argument, which is Socialism. For instance, characters in the novel are treated as types, that is, representatives of their class. Besides, the order of scenes and events has been rearranged for the purpose of foregrounding representative scenes like the description of the Brookers＇ lodging-house. The author＇s treatment of the material of the text is primarily based on his personal experience as an outside observer during his journey to the North. Therefore, the exploration of the novel from a structuralist perspective based on Genette＇s model does not merely aim at the pure application of some literary and critical approaches to Orwell＇s text. This may be misleading since the investigation may fall in superficiality and simplicity. But the strategy deployed is actually a further contribution to the author＇s general argument and a manifestation of the novel＇s status as a creative and subversive text.展开更多
The non-linear forced vibration of axially moving viscoelastic beams excited by the vibration of the supporting foundation is investigated. A non-linear partial-differential equation governing the transverse motion is...The non-linear forced vibration of axially moving viscoelastic beams excited by the vibration of the supporting foundation is investigated. A non-linear partial-differential equation governing the transverse motion is derived from the dynamical, constitutive equations and geometrical relations. By referring to the quasi-static stretch assumption, the partial-differential non-linearity is reduced to an integro-partial-differential one. The method of multiple scales is directly applied to the governing equations with the two types of non-linearity, respectively. The amplitude of near- and exact-resonant steady state is analyzed by use of the solvability condition of eliminating secular terms. Numerical results are presented to show the contributions of foundation vibration amplitude, viscoelastic damping, and nonlinearity to the response amplitude for the first and the second mode.展开更多
Unified analytical solutions are presented for the predictions of the stresses and displacements around a circular opening based on nonqinear unified failure criterion and the elastic-brittle-plastic softening model. ...Unified analytical solutions are presented for the predictions of the stresses and displacements around a circular opening based on nonqinear unified failure criterion and the elastic-brittle-plastic softening model. Unified analytical solutions not only involve generally traditional solutions which are based on the Hock-Brown （H-B） failure criterion or the non-linear twin-shear failure criterion, but also involve other new results. The results of the radius of plastic zone, radial displacements and stresses are obviously different using three rock masses when different values of the unified failure criterion parameter or different material behavior models are used. For a given condition, the radius of plastic zone and radial displacements are reduced by increasing the unified failure criterion parameter. The latent potentialities of rock mass result from considering the effect of intermediate principal stress. It is shown that proper choices of the failure criterion and the material behavior model for rock mass are significant in the tunnel design.展开更多
A non-linear non-ideal model, taking into account non-linear competitive isotherms, axial dispersion, film mass transfer, intraparticle diffusion, and port periodic switching, was developed to simulate the dynamics of...A non-linear non-ideal model, taking into account non-linear competitive isotherms, axial dispersion, film mass transfer, intraparticle diffusion, and port periodic switching, was developed to simulate the dynamics of simulated moving bed chromatography (SMBC). The model equations were solved by a new efficient numerical technique of orthogonal collocation on finite elements with periodical movement of concentration vector. The simulated SMBC performance is in accordance with the experimental results reported in the literature for separation of l,1'-bi-2-naphthol enantiomers using SMBC. This model is useful for design, operation, optimization and scale-up of non-linear SMBC for chiral separations with significant non-ideal effects, especially for high solute concentration and small intraparticle diffusion coefficient or large chiral stationary phase particle.展开更多
Creation of arbitrary features with high resolution is critically important in the fabrication of nano-optoelectronic devices.Here,sub-50 nm surface structuring is achieved directly on Sb2S3 thin films via microsphere...Creation of arbitrary features with high resolution is critically important in the fabrication of nano-optoelectronic devices.Here,sub-50 nm surface structuring is achieved directly on Sb2S3 thin films via microsphere femtosecond laser irradi-ation in far field.By varying laser fluence and scanning speed,nano-feature sizes can be flexibly tuned.Such small patterns are attributed to the co-effect of microsphere focusing,two-photons absorption,top threshold effect,and high-repetition-rate femtosecond laser-induced incubation effect.The minimum feature size can be reduced down to~30 nm(λ/26)by manipulating film thickness.The fitting analysis between the ablation width and depth predicts that the feature size can be down to~15 nm at the film thickness of~10 nm.A nano-grating is fabricated,which demonstrates desirable beam diffraction performance.This nano-scale resolution would be highly attractive for next-generation laser nano-lithography in far field and in ambient air.展开更多
Many simple nonlinear main journal bearing models have been studied theoretically, but the connection to existing engineering system has not been equally investigated. The consideration of the characteristics of engin...Many simple nonlinear main journal bearing models have been studied theoretically, but the connection to existing engineering system has not been equally investigated. The consideration of the characteristics of engine main journal bearings may provide a prediction of the bearing load and lubrication. Due to the strong non-linear features in bearing lubrication procedure, it is difficult to predict those characteristics. A non-linear dynamic model is described for analyzing the characteristics of engine main journal bearings. Components such as crankshaft, main journals and con rods are found by applying the finite element method. Non-linear spring/dampers are introduced to imitate the constraint and supporting functions provided by the main bearing and oil film. The engine gas pressure is imposed as excitation on the model via the engine piston, con rod, etc. The bearing reaction force is calculated over one engine cycle, and meanwhile, the oil film thickness and pressure distribution are obtained based on Reynolds differential equation. It can be found that the maximum bearing reaction force always occurs when the maximum cylinder pressure arises in the cylinder adjacent to that bearing. The simulated minimum oil film thickness, which is 3 μm, demonstrates the reliability of the main journal bearings. This non-linear dynamic analysis may save computing efforts of engine main bearing design and also is of good precision and close connection to actual engine main journal bearing conditions.展开更多
A relevance vector machine (RVM) based fault diagnosis method was presented for non-linear circuits. In order to simplify RVM classifier, parameters selection based on particle swarm optimization (PSO) and preprocessi...A relevance vector machine (RVM) based fault diagnosis method was presented for non-linear circuits. In order to simplify RVM classifier, parameters selection based on particle swarm optimization (PSO) and preprocessing technique based on the kurtosis and entropy of signals were used. Firstly, sinusoidal inputs with different frequencies were applied to the circuit under test (CUT). Then, the resulting frequency responses were sampled to generate features. The frequency response was sampled to compute its kurtosis and entropy, which can show the information capacity of signal. By analyzing the output signals, the proposed method can detect and identify faulty components in circuits. The results indicate that the fault classes can be classified correctly for at least 99% of the test data in example circuit. And the proposed method can diagnose hard and soft faults.展开更多
In this paper the authors study a class of non-linear singular partial differential equation in complex domain C-_(t)×C_(x)^(n).Under certain assumptions,they prove the existence and uniqueness of holomorphic sol...In this paper the authors study a class of non-linear singular partial differential equation in complex domain C-_(t)×C_(x)^(n).Under certain assumptions,they prove the existence and uniqueness of holomorphic solution near origin of C-_(t)×C-_(x)^(n).展开更多
基金supported by the German Research Foundation(DFG), the State of Baden-Württemberg, and the University(TH) of Karlsruhe
文摘In the past decades, the necessity for detailed earthquake microzonation studies was recognized worldwide. Therefore, different approaches were established and applied. Unfortunately, the majority of these approaches are not based on pre-existing field data but require extensive seismic measurements and investigations. Furthermore, these approaches incorporate non-linearity inadequately and cannot take groundwater level changes into account. For this purpose, notably numerical models are most suitable. These models require a good knowledge of the local geological conditions （especially of the uppermost unconsolidated units）, information about the geotechnical parameters of these units, and a hydrogeological model of the investigated area. Most of this information can be obtained from geotechnical investigations and surveys that have already been carried out in most densely populated areas. In a case study for Bucharest City, non-linear analyses were performed using software that is based on the visco-hypoplastic constitutive law. The results indicate that groundwater level changes have an important influence on duration and amplitude of ground response and thus should be considered for seismic microzonation studies. This approach ean be used to display site effects and to identify different microzones taking different earthquake magnitudes and groundwater levels into account.
基金Project supported by the Department of Science and Technology(DST),Govt.of India
文摘CeO2/TiO2 composite nanoparticles with different Ce/Ti molar ratios have been successfully synthesized via sol-gel method. It was found that the band gap of the nanocomposite is tunable by varying Ce/Ti content. The nonlinear response of the sample was studied by using the nanosecond laser pulses from a Q switched Nd：Yag laser employing the Z-scan method. Open aperture Z-scan experiment revealed that with the increase in the CeO2 amount in the nanocomposite, the non-linearity of the composite increases, and it was assumed that this could be due to the modification of TiO2 dipole symmetry by the addition of CeO2. Closed aperture Z-scan experiment showed that when the CeO2 amount increases, positive nonlinear refraction decreases, and this could be attributed to the increase in the two photon absorption which subsequently suppresses the nonlinear refraction.
文摘A gyro-stabilizer is the interesting system that it can apply to marine vessels for diminishes roll motion.Today it has potentially light weight with no hydrodynamics drag and effective at zero forward speed.The twin-gyroscope was chosen.Almost,the modelling for designing the system use linear model that it might not comprehensive mission requirement such as high sea condition.The non-linearity analysis was proved by comparison the results between linear and non-linear model of gyro-stabilizer throughout frequency domain also same wave input,constrains and limitations.Moreover,they were cross checked by simulating in time domain.The comparison of interested of linear and non-linear close loop model in frequency domain has demonstrated the similar characteristics but gave different values at same frequency obviously.The results were confirmed again by simulation in irregular beam sea on time domain and they demonstrate the difference of behavior of both systems while the gyro-stabilizers are switching on and off.From the resulting analysis,the non-linear gyro-stabilizer model gives more real results that correspond to more accuracy in a designing gyro-stabilizer control system for various amplitudes and frequencies operating condition especially high sea condition.
文摘Electrochemical impedance spectroscopy,a method for battery diagnostics,is used to estimate the internal temperature of a lithium-ion battery cell during highly dynamic load profiles.For the first time,a recurrent neural network is trained and evaluated with operando impedance data for temperature estimation.Furthermore,an approach is considered that guides the training process of the neural network by incorporating physical constraints.The model’s development based on an extensive series of measurements with different load profiles,tested under realistic conditions on large-format lithium-ion cells.The estimation accuracy of the data-driven approach is evaluated and compared against model-based methods,including the extended Kalman filter.An impedance correction model is proposed,which leads to a significant enhancement of the model-based estimation.The recurrent neural network under consideration achieves a mean square error of 1.07℃ for the investigated testing profiles in the temperature range up to 60℃.
基金partially supported by theNational Key Research and Development Program of China(Grant No.2016YFA0600203)the High-resolution Earth Observation System Major Special Project(CHEOS)(Grant No.32-Y20A17-9001-15/17)+1 种基金the National Natural Science Foundation of China(Grant No.41575100)the Special Fund for Meteorological Scientific Research in Public Interest(Grant No.GYHY201306045)
文摘The Proper Orthogonal Decomposition(POD)-based ensemble four-dimensional variational(4DVar) assimilation method(POD4DEnVar) was proposed to combine the strengths of EnKF(i.e.,the ensemble Kalman filter) and 4DVar assimilation methods.Recently,a POD4DEnVar-based radar data assimilation scheme(PRAS) was built and its effectiveness was demonstrated.POD4 DEnVar is based on the assumption of a linear relationship between the model perturbations(MPs)and the observation perturbations(OPs);however,this assumption is likely to be destroyed by the highly non-linear forecast model or observation operator.To address this issue,using the Gauss-Newton iterative method,the nonlinear least squares enhanced POD4 DEnVar algorithm(referred to as NLS-4DVar) was proposed.Naturally,the PRAS was upgraded to form the NLS-4DVar-based radar data assimilation scheme(NRAS).To evaluate the performance of NRAS against PRAS,observing system simulation experiments(OSSEs) were conducted to assimilate reflectivity and radial velocity individually,with one,two,and three iterations.The results demonstrated that the NRAS outperformed PRAS in improving the initial condition and the forecasting of model variables and rainfall.The NRAS,with a smaller number of iterations,can yield a convergent result.In contrast to the situation when assimilating radial velocity,the advantages of NRAS over PRAS were more obvious when assimilating reflectivity.
基金Supported by National Natural Science Foundation of China(Grant No.11872033)Beijing Municipal Natural Science Foundation(Grant No.3172017)。
文摘Many experiments have supported the contact models,such as the GW and MB models,but the majority of previous validations have been performed under light loads,resulting in a linear relationship between normal force and contact area.However,the real contact area fraction should never equal one;there must be a limit smaller than the apparent area,implying that the real contact area cannot increase linearly indefinitely.In this paper,the real contact area between two polymethylmethacrylate(PMMA)blocks under heavy load is measured using the total reflection method,and the contact area is analyzed using the image processing method.The results show that the real contact area increases with normal load linearly in light loads but non-linearly in heavy loads;the number of contact spots increases with load linearly in light loads but also non-linearly in heavy loads,synchronous with the change in the real contact area.The GW,MB,and Zhao,Maietta,and Chang(ZMC)models were used to predict the experiment results,but none of them predicted the non-linear stage.A revised GW model based on the bulk deformation hypothesis performs better in predicting the non-linear stage.The study’s findings can be applied to PMMA or other similar materials,and they can serve as a useful reference for future research on the contact mechanisms of other materials.
基金This work was supported by the Youth Project of Hunan Provincial Department of Education(Grant No.22B0334)the Bridge and Tunnel Engineering Innovation Project of Changsha University of Science&Technology(Grant No.11ZDXK11)and the Practical Innovation and Entrepreneurship Capacity Improvement Plan of Changsha University of Science and Technology(Grant No.CLSJCX23029).
文摘Organisms have evolved a strain limiting mechanism,reflected as a non-linear elastic constitutive,to prevent large deformations from threatening soft tissue integrity.Compared with linear elastic substrates,the wrinkle of films on non-linear elastic substrates has received less attention.In this article,a unique wrinkle evolution of the film-substrate system with a J-shaped non-linear stress-strain relation is reported.The result shows that a concave hexagonal array pattern is formed with the shrinkage strain of the film-substrate systems developing.As the interconnection of hexagonal arrays,a unit cell ridge network appears with properties such as chirality and helix.The subparagraph maze pattern formed with high compression is mainly composed of special single-cell ridge networks such as spiral single cores,chiral double cores,and combined multi-cores.This evolutionary model is highly consistent with the results of experiments,and it also predicts wrinkle morphology that has not yet been reported.These findings can serve as a novel explanation for the surface wrinkle of biological soft tissue,as well as provide references for the preparation of artificial biomaterials and programmable soft matter.
文摘This opinion article discusses the original research work of Yünkül et al.(the Authors)published in the Journal of Mountain Science 21(9):3108–3122.Employing non-linear regression,fuzzy logic and artificial neural network modeling techniques,the Authors interrogated a large database assembled from the existing research literature to assess the performance of twelve equation rules in predicting the undrained shear strength(s_(u))mobilized for remolded fine-grained soils at different values of liquidity index(I_(L))and water content ratio.Based on their analyses,the Authors proposed a simple and reportedly reliable correlation(i.e.,Eq.9 in their paper)for predicting s_(u) over the I_(L) range of 0.15 to 3.00.This article describes various shortcomings in the Authors’assembled database(including potentially anomalous data and covering an excessively wide I_(L) range in relation to routine geotechnical and transportation engineering applications)and their proposed s_(u)=f(I_(L))correlation.Contrary to the Authors’assertions,their proposed correlation is not reliable for fine-grained soils with consistencies in the general firm to stiff range(i.e.,for 0.15<I_(L)<0.40),increasingly overestimating s_(u) for reducing I_(L),and eventually predicting s_(u)→+∞for I_(L)→0.15+(while producing mathematically undefined s_(u) for I_(L)<0.15),thus rendering their correlation unconservative and potentially leading to unsafe geotechnical designs.Exponential or regular-power type s_(u)=f(I_(L))models are more s_(u)itable when developing correlations that are applicable over the full plastic range(of 0<I_(L)<1),thereby providing reasonably conservative s_(u) predictions for use in the preliminary design for routine geotechnical engineering applications.
基金This paper is supported by China Petrochemical Key Project in the"11th Five-Year"Plan Technology and the Doctorate Fund of Ministry of Education of China (No.20050491504)
文摘Wavelet transforms have been successfully used in seismic data processing with their ability for local time - frequency analysis. However, identification of directionality is limited because wavelet transform coefficients reveal only three spatial orientations. Whereas the ridgelet transform has a superior capability for direction detection and the ability to process signals with linearly changing characteristics. In this paper, we present the issue of low signal-to-noise ratio （SNR） seismic data processing based on the ridgelet transform. Actual seismic data with low SNR from south China has been processed using ridgelet transforms to improve the SNR and the continuity of seismic events. The results show that the ridgelet transform is better than the wavelet transform for these tasks.
基金Project(2014GK2013)supported by the Science and Technology Program of Hunan Province,China
文摘The microstructure evolution and properties of an Al-Zn-Mg-Cu alloy were investigated under different non-linear cooling processes from the solution temperature, combined with in-situ electrical resistivity measurements, selected area diffraction patterns （SADPs）, transmission electron microscopy （TEM）, and tensile tests. The relative resistivity was calculated to characterize the phase transformation of the experimental alloy during different cooling processes. The results show that at high temperatures, the microstructure evolutions change from the directional diffusion of Zn and Mg atoms to the precipitation of S phase, depending on the cooling rate. At medium temperatures, q phase nucleates on A13Zr dispersoids and grain boundaries under fast cooling conditions, while S phase precipitates under the slow cooling conditions. The strength and ductility of the aged alloy suffer a significant deterioration due to the heterogeneous precipitation in medium temperature range. At low temperatures, homogeneously nucleated GP zone, η′ and η phases precipitate.
文摘In this paper, the characteristics of different forms of mild slope equations for non-linear wave are analyzed, and new non-linear theoretic models for wave propagation are presented, with non-linear terms added to the mild slope equations for non-stationary linear waves and dissipative effects considered. Numerical simulation models are developed of non-linear wave propagation for waters of mildly varying topography with complicated boundary, and the effects are studied of different non-linear corrections on calculation results of extended mild slope equations. Systematical numerical simulation tests show that the present models can effectively reflect non-linear effects.
文摘Numerical experiments on non-linear equations of the 1st-and 3rd-order derivatives have been carried out through structural analyses in the phase space according to the numerical instability of ill-posed systems,with changes of initial values and parameters,etc..The results show that the quantitative instability in an ill-posed system may reveal reversed transformation in system evolution by structural representation,and confirm A·Dauglas' theorem that "a non-linear equation does not satisfy the existence of the initial value in a linear well-posed system".
文摘Orwell＇s text The Road to Wigan Pier, henceforth referred to as RWP, is problematic due to the ambiguity of its status as a literary genre. The text is subversive on many levels, namely on the level of form. In order to show some aspects of the author＇s challenge of the conventional norms and methods of literary writing, a comparison between the writer＇s original diary of the journey to the industrial North of England, the main site of the coal mines, and the present book could be of great import. This reveals the author＇s genuine intellectual ability to manipulate and rearrange the events and scenes of the story on the discourse level. The author＇s manipulation and rearrangement of the story （the journey）, events and scenes, clearly reveals his potential literary creativity and imagination. Orwell has deployed many strategies to fulfil this purpose. Each strategy is actually a contribution to the author＇s overall argument and at the same time it constitutes a further aspect of subversion. The first aspect of subversion lies on the level of form itself. The form of the book is effectively very challenging. Contrary to the conventional view of the fictional novel, the study of Orwell＇s text based on Grrard Genette＇s model reveals his challenge of the basic novelistic parameters. The novelistic ingredients such as setting, characterisation, and plot development have been treated in a subverting way. Though not totally discarded, they have been manipulated for the purpose of the author＇s general argument, which is Socialism. For instance, characters in the novel are treated as types, that is, representatives of their class. Besides, the order of scenes and events has been rearranged for the purpose of foregrounding representative scenes like the description of the Brookers＇ lodging-house. The author＇s treatment of the material of the text is primarily based on his personal experience as an outside observer during his journey to the North. Therefore, the exploration of the novel from a structuralist perspective based on Genette＇s model does not merely aim at the pure application of some literary and critical approaches to Orwell＇s text. This may be misleading since the investigation may fall in superficiality and simplicity. But the strategy deployed is actually a further contribution to the author＇s general argument and a manifestation of the novel＇s status as a creative and subversive text.
基金Project supported by the National Natural Science Foundation of China (No. 10472060)Natural Science Founda-tion of Shanghai Municipality (No. 04ZR14058)Doctor Start-up Foundation of Shenyang Institute of Aeronautical Engineering (No. 05YB04).
文摘The non-linear forced vibration of axially moving viscoelastic beams excited by the vibration of the supporting foundation is investigated. A non-linear partial-differential equation governing the transverse motion is derived from the dynamical, constitutive equations and geometrical relations. By referring to the quasi-static stretch assumption, the partial-differential non-linearity is reduced to an integro-partial-differential one. The method of multiple scales is directly applied to the governing equations with the two types of non-linearity, respectively. The amplitude of near- and exact-resonant steady state is analyzed by use of the solvability condition of eliminating secular terms. Numerical results are presented to show the contributions of foundation vibration amplitude, viscoelastic damping, and nonlinearity to the response amplitude for the first and the second mode.
基金Project (No.SJ08E204) supported by the Natural Science Foundation of Shanxi Province,China
文摘Unified analytical solutions are presented for the predictions of the stresses and displacements around a circular opening based on nonqinear unified failure criterion and the elastic-brittle-plastic softening model. Unified analytical solutions not only involve generally traditional solutions which are based on the Hock-Brown （H-B） failure criterion or the non-linear twin-shear failure criterion, but also involve other new results. The results of the radius of plastic zone, radial displacements and stresses are obviously different using three rock masses when different values of the unified failure criterion parameter or different material behavior models are used. For a given condition, the radius of plastic zone and radial displacements are reduced by increasing the unified failure criterion parameter. The latent potentialities of rock mass result from considering the effect of intermediate principal stress. It is shown that proper choices of the failure criterion and the material behavior model for rock mass are significant in the tunnel design.
基金Supported by the National Natural Science Foundation of China(No.20206027)and the Natural Science Foundation of Zhejiang Province(No.202046).
文摘A non-linear non-ideal model, taking into account non-linear competitive isotherms, axial dispersion, film mass transfer, intraparticle diffusion, and port periodic switching, was developed to simulate the dynamics of simulated moving bed chromatography (SMBC). The model equations were solved by a new efficient numerical technique of orthogonal collocation on finite elements with periodical movement of concentration vector. The simulated SMBC performance is in accordance with the experimental results reported in the literature for separation of l,1'-bi-2-naphthol enantiomers using SMBC. This model is useful for design, operation, optimization and scale-up of non-linear SMBC for chiral separations with significant non-ideal effects, especially for high solute concentration and small intraparticle diffusion coefficient or large chiral stationary phase particle.
基金This work is supported by Academic Research Fund Tier 2,Ministry of Education-Singapore(MOE2019-T2-2-147)T.C.acknowledges support from the National Key Research and Development Program of China(2019YFA0709100,2020YFA0714504).
文摘Creation of arbitrary features with high resolution is critically important in the fabrication of nano-optoelectronic devices.Here,sub-50 nm surface structuring is achieved directly on Sb2S3 thin films via microsphere femtosecond laser irradi-ation in far field.By varying laser fluence and scanning speed,nano-feature sizes can be flexibly tuned.Such small patterns are attributed to the co-effect of microsphere focusing,two-photons absorption,top threshold effect,and high-repetition-rate femtosecond laser-induced incubation effect.The minimum feature size can be reduced down to~30 nm(λ/26)by manipulating film thickness.The fitting analysis between the ablation width and depth predicts that the feature size can be down to~15 nm at the film thickness of~10 nm.A nano-grating is fabricated,which demonstrates desirable beam diffraction performance.This nano-scale resolution would be highly attractive for next-generation laser nano-lithography in far field and in ambient air.
基金supported by National Natural Science Foundation of China (Grant No. 60879002)National Hi-tech Research and Development Program of China (863 Program, Grant No. 2006AA110112)
文摘Many simple nonlinear main journal bearing models have been studied theoretically, but the connection to existing engineering system has not been equally investigated. The consideration of the characteristics of engine main journal bearings may provide a prediction of the bearing load and lubrication. Due to the strong non-linear features in bearing lubrication procedure, it is difficult to predict those characteristics. A non-linear dynamic model is described for analyzing the characteristics of engine main journal bearings. Components such as crankshaft, main journals and con rods are found by applying the finite element method. Non-linear spring/dampers are introduced to imitate the constraint and supporting functions provided by the main bearing and oil film. The engine gas pressure is imposed as excitation on the model via the engine piston, con rod, etc. The bearing reaction force is calculated over one engine cycle, and meanwhile, the oil film thickness and pressure distribution are obtained based on Reynolds differential equation. It can be found that the maximum bearing reaction force always occurs when the maximum cylinder pressure arises in the cylinder adjacent to that bearing. The simulated minimum oil film thickness, which is 3 μm, demonstrates the reliability of the main journal bearings. This non-linear dynamic analysis may save computing efforts of engine main bearing design and also is of good precision and close connection to actual engine main journal bearing conditions.
基金Project(Z132012)supported by the Second Five Technology-based in Science and Industry Bureau of ChinaProject(YWF1103Q062)supported by the Fundemental Research Funds for the Central Universities in China
文摘A relevance vector machine (RVM) based fault diagnosis method was presented for non-linear circuits. In order to simplify RVM classifier, parameters selection based on particle swarm optimization (PSO) and preprocessing technique based on the kurtosis and entropy of signals were used. Firstly, sinusoidal inputs with different frequencies were applied to the circuit under test (CUT). Then, the resulting frequency responses were sampled to generate features. The frequency response was sampled to compute its kurtosis and entropy, which can show the information capacity of signal. By analyzing the output signals, the proposed method can detect and identify faulty components in circuits. The results indicate that the fault classes can be classified correctly for at least 99% of the test data in example circuit. And the proposed method can diagnose hard and soft faults.
文摘In this paper the authors study a class of non-linear singular partial differential equation in complex domain C-_(t)×C_(x)^(n).Under certain assumptions,they prove the existence and uniqueness of holomorphic solution near origin of C-_(t)×C-_(x)^(n).
