The internal pressure within fission gas bubbles(FGBs)in irradiated nuclear fuels drives mechanical interactions with the surrounding fuel skeleton.To investigate the micromechanical stress fields in irradiated nuclea...The internal pressure within fission gas bubbles(FGBs)in irradiated nuclear fuels drives mechanical interactions with the surrounding fuel skeleton.To investigate the micromechanical stress fields in irradiated nuclear fuels containing pressurized FGBs,a mechanical constitutive model for the equivalent solid of FGBs was developed and validated.This model was based on the modified Van der Waals equation,incorporating the effects of surface tension.Using this model,the micromechanical fields in irradiated U-10Mo fuels with randomly distributed FGBs were calculated during uniaxial tensile testing via the finite element(FE)method.The macroscopic elastic constants of the irradiated U-10Mo fuels were then derived using homogenization theory,and the influences of bubble pressure,bubble size,and porosity on these constants were examined.Results show that adjacent FGBs exhibit mechanical interactions,which leads to distinct stress concentrations in the surrounding fuel skeleton.The macroscopic elastic constants of irradiated U-10Mo fuels decrease with increasing the macroscopic porosity,which can be quantitatively described by the Mori-Tanaka model.In contrast,bubble pressure and size have negligible effects on these constants.展开更多
Enzymatic hydrolysis of proteins is a breakdown process of peptide bond in proteins,releasing some peptides with potential biological functions.Previous studies on enzymatic hydrolysis of whey proteins have not identi...Enzymatic hydrolysis of proteins is a breakdown process of peptide bond in proteins,releasing some peptides with potential biological functions.Previous studies on enzymatic hydrolysis of whey proteins have not identified the complete peptide profiles after hydrolysis.In this study,we reconstructed a profile of peptides from whey hydrolysates with two enzymes and different processing conditions.We also developed an ensemble machine learning predictor to classify peptides obtained from whey hydrolysis.A total of 2572 peptides were identified over three process conditions with two enzymes in duplicate.499 peptides were classified and chosen as potential antioxidant peptides from whey proteins.The peptides classified as antioxidants in the hydrolysates had a proportion of 13.1%-24.5%regarding all peptides identified.These results facilitate the selection of promising peptides involved in the antioxidant properties during the enzymatic hydrolysis of whey proteins,aiding the discovery of novel antioxidant peptides.展开更多
Hard-magnetic soft materials have attracted broad interests because of their flexible programmability,non-contact activation and rapid response in various applications such as soft robotics,biomedical devices and flex...Hard-magnetic soft materials have attracted broad interests because of their flexible programmability,non-contact activation and rapid response in various applications such as soft robotics,biomedical devices and flexible electronics.Such multifunctional materials consist of a soft matrix embedded with hard-magnetic particles,and can exhibit large deformations under external magnetic stimuli.Here,we develop a three-dimensional(3D)rod model to predict spatial deformations(extension,bending and twist)of slender hard-magnetic elastica.The model follows Kirchhoff hypothesis and thus reduces the 3D magneto-elastic energy function to a one-dimensional(1D)form.Besides,the co-rotational formulation is applied to describe rigid body motion,and explicit time integration is adopted for the nonlinear resolution.Moreover,we explore finite bending,post-buckling and twisting of hard-magnetic elastica under external magnetic fields with different directions and amplitudes.Representative examples with various configurations show superior efficiency and accuracy of the model(the difference less than 1%with only a small number of elements)compared to conventional solid element.Our model could be used to guide rational designs on programmable shape morphing of ferromagnetic slender structures.展开更多
Models to describe the damage and fracture behaviors of the interface between the fuel foil and cladding in UMo/Zr monolithic fuel plates were established and numerically implemented.The effects of the interfacial coh...Models to describe the damage and fracture behaviors of the interface between the fuel foil and cladding in UMo/Zr monolithic fuel plates were established and numerically implemented.The effects of the interfacial cohesive strength and cohesive energy on the irradiationinduced thermal-mechanical behaviors of fuel plates were investigated.The results indicated that for heterogeneously irradiated fuel plates:(1)interfacial damage and failure were predicted to be initiated near the fuel foil corner with higher fission densities,accompanied by the formation of a large gap after interface failure,which was consistent with some experimental observations;high tensile stresses in the fuel foil occurred near the edges of the failed interface,attributed to through-thickness cracking of the fuel foil,as found in some post-irradiation examinations;(2)the cohesive strength and cohesive energy of the interface both influenced the in-pile evolution behaviors of fuel plates;a lower cohesive strength or cohesive energy resulted in faster interfacial damage;(3)after interface fracture,the thickness of the whole plate increased to a greater degree(by~20%)than that of the samples without interfacial damage,which was attributed to the locally enhanced Mises stresses and the nearby creep deformations around the cracked interface.This study provided a theoretical basis for assessing failure in fuel elements.展开更多
Cloud computing describes highly scalable computing resources provided as an external service via the internet. Economically, the main feature of cloud computing is that customers only use what they need, and only pay...Cloud computing describes highly scalable computing resources provided as an external service via the internet. Economically, the main feature of cloud computing is that customers only use what they need, and only pay for what they actually use. Resources are available to be accessed from the cloud at any time, and from any location via the internet. There’s no need to worry about how things are being maintained behind the scenes—you simply purchase the IT service you require. This new, web-based generation of computing utilizes remote servers for data storage and management. One of the challenging issues tackled in the cloud computing is the security of data stored in the service providers’ site. In this paper, we propose a new architecture for secure data storage in such a way that users’ data are encrypted and split into various cipher blocks and distributed among different service providers site rather than solely depend on single provider for data storage. This architecture ensures better reliability, availability, scalability and security.展开更多
Granular packings under gravity in frictional and frictionless silos were simulated and the influence of the wall friction on the normal force distribution was investigated. Although there is an obvious Janssen effect...Granular packings under gravity in frictional and frictionless silos were simulated and the influence of the wall friction on the normal force distribution was investigated. Although there is an obvious Janssen effect in frictional silos, only a slight influence on the geometry of packing was found. The law of normal force distribution is different for frictional and frictionless walls, which is related to the pressure profile. A modified formula with consideration of the pressure profile was well fitted to the simulation results.展开更多
The multi-robot systems(MRS)exploration and fire searching problem is an important application of mobile robots which require massive computation capability that exceeds the ability of traditional MRS′s.This paper pr...The multi-robot systems(MRS)exploration and fire searching problem is an important application of mobile robots which require massive computation capability that exceeds the ability of traditional MRS′s.This paper propose a cloud-based hybrid decentralized partially observable semi-Markov decision process(HDec-POSMDPs)model.The proposed model is implemented for MRS exploration and fire searching application based on the Internet of things(IoT)cloud robotics framework.In this implementation the heavy and expensive computational tasks are offloaded to the cloud servers.The proposed model achieves a significant improvement in the computation burden of the whole task relative to a traditional MRS.The proposed model is applied to explore and search for fire objects in an unknown environment;using different sets of robots sizes.The preliminary evaluation of this implementation demonstrates that as the parallelism of computational instances increase the delay of new actuation commands which will be decreased,the mean time of task completion is decreased,the number of turns in the path from the start pose cells to the target cells is minimized and the energy consumption for each robot is reduced.展开更多
A finite-strain homogenization creep model for composite fuels under irradiation conditions is developed and verified,with the irradiation creep strains of the fuel particles and matrix correlated to the macroscale cr...A finite-strain homogenization creep model for composite fuels under irradiation conditions is developed and verified,with the irradiation creep strains of the fuel particles and matrix correlated to the macroscale creep responses,excluding the contributions of volumetric strain induced by the irradiation swelling deformations of fuel particles.A finite element(FE)modeling method for uniaxial tensile creep tests is established with the irradiation effects of nuclear materials taken into account.The proposed models and simulation strategy are numerically implemented to a kind of composite nuclear fuel,and the predicted mesoscale creep behaviors and the macroscale creep responses are investigated.The research results indicate that:(1)the macroscale creep responses and the mesoscale stress and strain fields are all greatly affected by the irradiation swelling of fuel particles,owing to the strengthened mechanical interactions between the fuel particles and the matrix.(2)The effective creep rates for a certain case are approximately two constants before and after the critical fission density,which results from the accelerated fission gas swelling after fuel grain recrystallization,and the effects of macroscale tensile stress will be more enhanced at higher temperatures.(3)The macroscale creep contributions from the fuel particles and matrix depend mainly on the current volume fractions varying with fission density.(4)As a function of the macroscale stress,temperature,initial particle volume fraction and particle fission rate,a multi-variable mathematical model for effective creep rates is fitted out for the considered composite fuels,which matches well with the FE predictions.This study supplies important theoretical models and research methods for the multi-scale creep behaviors of various composite fuels and provides a basis for simulation of the thermal–mechanical behavior in related composite fuel elements and assemblies.展开更多
A high resolution upwind compact streamfunction numerical algorithm for two-dimensional(2D)double-diffusive convection(DDC)is developed.The unsteady Navier-Stokes(N-S)equations in the streamfunction-velocity form and ...A high resolution upwind compact streamfunction numerical algorithm for two-dimensional(2D)double-diffusive convection(DDC)is developed.The unsteady Navier-Stokes(N-S)equations in the streamfunction-velocity form and the scalar temperature and concentration equations are used.An optimized third-order upwind compact(UCD3 opt)scheme with a low dispersion error for the first derivatives is utilized to approximate the third derivatives of the streamfunction in the advection terms of the N-S equations and the first derivatives in the advection terms of the scalar temperature and concentration equations.The remaining first derivatives of the streamfunction(velocity),temperature,and concentration variables used in the governing equations are discretized by the fourth-order compact Pade(SCD4)schemes.With the temperature and concentration variables and their approximate values of the first derivatives obtained by the SCD4 schemes,the explicit fourth-order compact schemes are suggested to approximate the second derivatives of temperature and concentration in the diffusion terms of the energy and concentration equations.The discretization of the temporal term is executed with the second-order Crank-Nicolson(C-N)scheme.To assess the spatial behavior capability of the established numerical algorithm and verify the developed computer code,the DDC flow is numerically solved.The obtained results agree well with the benchmark solutions and some accurate results available in the literature,verifying the accuracy,effectiveness,and robustness of the provided algorithm.Finally,a preliminary application of the proposed method to the DDC is carried out.展开更多
One of the most common kinds of cancer is breast cancer.The early detection of it may help lower its overall rates of mortality.In this paper,we robustly propose a novel approach for detecting and classifying breast c...One of the most common kinds of cancer is breast cancer.The early detection of it may help lower its overall rates of mortality.In this paper,we robustly propose a novel approach for detecting and classifying breast cancer regions in thermal images.The proposed approach starts with data preprocessing the input images and segmenting the significant regions of interest.In addition,to properly train the machine learning models,data augmentation is applied to increase the number of segmented regions using various scaling ratios.On the other hand,to extract the relevant features from the breast cancer cases,a set of deep neural networks(VGGNet,ResNet-50,AlexNet,and GoogLeNet)are employed.The resulting set of features is processed using the binary dipper throated algorithm to select the most effective features that can realize high classification accuracy.The selected features are used to train a neural network to finally classify the thermal images of breast cancer.To achieve accurate classification,the parameters of the employed neural network are optimized using the continuous dipper throated optimization algorithm.Experimental results show the effectiveness of the proposed approach in classifying the breast cancer cases when compared to other recent approaches in the literature.Moreover,several experiments were conducted to compare the performance of the proposed approach with the other approaches.The results of these experiments emphasized the superiority of the proposed approach.展开更多
Mechanical stimulation,such as fluid-induced wall shear stress(WSS),is known that can influence the cellular behaviours.Therefore,in some tissue engineering experiments in vitro,mechanical stimulation is applied via b...Mechanical stimulation,such as fluid-induced wall shear stress(WSS),is known that can influence the cellular behaviours.Therefore,in some tissue engineering experiments in vitro,mechanical stimulation is applied via bioreactors to the cells in cell culturing to study cell physiology and pathology.In 3D cell culturing,porous scaffolds are used for housing the cells.It is known that the scaffold porous geometries can influence the scaffold permeability and internal WSS in a bioreactor(such as perfusion bioreactor).To calculate the WSS generated on cells within scaffolds,usually computational fluid dynamics(CFD)simulation is needed.However,the limitations of the computational method for WSS calculation are:(i)the high time cost of the CFD simulation(in particular for the highly irregular geometries);(ii)accessibility to the CFD model for some cell culturing experimentalists due to the knowledge gap.To address these limitations,this study aims to develop an empirical model for calculating the WSS based on scaffold permeability.This model can allow the tissue engineers to efficiently calculate the WSS generated within the scaffold and/or determine the bioreactor loading without performing the computational simulations.展开更多
Surface instability of compliant film/substrate bilayers has raised considerable interests due to its broad applications such as wrinkle-driven surface renewal and antifouling,shape-morphing for camouflaging skins,and...Surface instability of compliant film/substrate bilayers has raised considerable interests due to its broad applications such as wrinkle-driven surface renewal and antifouling,shape-morphing for camouflaging skins,and micro/nano-scale surface patterning control.However,it is still a challenge to precisely predict and continuously trace secondary bifurcation transitions in the nonlinear post-buckling region.Here,we develop lattice models to precisely capture the nonlinear morphology evolution with multiple mode transitions that occur in the film/substrate systems.Based on our models,we reveal an intricate post-buckling phenomenon involving successive flat-wrinkle-doubling-quadrupling-fold bifurcations.Pre-stretch and pre-compression of the substrate,as well as bilayer modulus ratio,can alter surface morphology of film/substrate bilayers.With high substrate pre-tension,hierarchical wrinkles emerge in the bilayer with a low modulus ratio,while a wrinkle-to-ridge transition occurs with a high modulus ratio.Besides,with moderate substrate pre-compression,the bilayer eventually evolves into a period-tripling mode.Phase diagrams based on neo-Hookean and Arruda-Boyce constitutions are drawn to characterize the influences of different factors and to provide an overall view of ultimate pattern formation.Fundamental understanding and quantitative prediction of the nonlinear morphological transitions of soft bilayer materials hold potential for multifunctional surface regulation.展开更多
Mechanoluminescence has attracted increasing attentions because it can convert the kinetic energy during human daily motions into light to be used in sensors and displays. However, its practical applications are still...Mechanoluminescence has attracted increasing attentions because it can convert the kinetic energy during human daily motions into light to be used in sensors and displays. However, its practical applications are still hindered by the weak brightness and limited color while under large forces. Herein, we developed novel piezoluminescent devices(PLDs) which could effectively emit visible light under low pressing forces through the stress-concentration and enhancing deformation on the basis of carefully-designed array structures. The emitting colors were also tunable by using bilayer luminescent film under different pressures. This work not only provides a new strategy to effectively harvest mechanical energy into light,but also presents a scalable, low-cost and color-tunable PLD which shows great potentials in various applications such as luminescent floors, shoes and stress-activated displays.展开更多
基金National Natural Science Foundation of China(12135008,12132005)。
文摘The internal pressure within fission gas bubbles(FGBs)in irradiated nuclear fuels drives mechanical interactions with the surrounding fuel skeleton.To investigate the micromechanical stress fields in irradiated nuclear fuels containing pressurized FGBs,a mechanical constitutive model for the equivalent solid of FGBs was developed and validated.This model was based on the modified Van der Waals equation,incorporating the effects of surface tension.Using this model,the micromechanical fields in irradiated U-10Mo fuels with randomly distributed FGBs were calculated during uniaxial tensile testing via the finite element(FE)method.The macroscopic elastic constants of the irradiated U-10Mo fuels were then derived using homogenization theory,and the influences of bubble pressure,bubble size,and porosity on these constants were examined.Results show that adjacent FGBs exhibit mechanical interactions,which leads to distinct stress concentrations in the surrounding fuel skeleton.The macroscopic elastic constants of irradiated U-10Mo fuels decrease with increasing the macroscopic porosity,which can be quantitatively described by the Mori-Tanaka model.In contrast,bubble pressure and size have negligible effects on these constants.
基金supported and funded by the Gobernación del Cesar-Ministry of Science,Technology,and Innovation through resources for the higher education(grant 736/2015)the Natural Sciences and Engineering Research Council of Canada(NSERC)。
文摘Enzymatic hydrolysis of proteins is a breakdown process of peptide bond in proteins,releasing some peptides with potential biological functions.Previous studies on enzymatic hydrolysis of whey proteins have not identified the complete peptide profiles after hydrolysis.In this study,we reconstructed a profile of peptides from whey hydrolysates with two enzymes and different processing conditions.We also developed an ensemble machine learning predictor to classify peptides obtained from whey hydrolysis.A total of 2572 peptides were identified over three process conditions with two enzymes in duplicate.499 peptides were classified and chosen as potential antioxidant peptides from whey proteins.The peptides classified as antioxidants in the hydrolysates had a proportion of 13.1%-24.5%regarding all peptides identified.These results facilitate the selection of promising peptides involved in the antioxidant properties during the enzymatic hydrolysis of whey proteins,aiding the discovery of novel antioxidant peptides.
基金This work was supported by the National Natural Science Foundation of China(Grants Nos.12122204,11872150,and 11890673)Shanghai Pilot Program for Basic Research-Fudan University(Grant No.21TQ1400100-21TQ010)+2 种基金Shanghai Shuguang Program(Grant No.21SG05)Shanghai Rising-Star Program(Grant No.19QA1400500)Young Scientist Project of Ministry of Education Innovation Platform.
文摘Hard-magnetic soft materials have attracted broad interests because of their flexible programmability,non-contact activation and rapid response in various applications such as soft robotics,biomedical devices and flexible electronics.Such multifunctional materials consist of a soft matrix embedded with hard-magnetic particles,and can exhibit large deformations under external magnetic stimuli.Here,we develop a three-dimensional(3D)rod model to predict spatial deformations(extension,bending and twist)of slender hard-magnetic elastica.The model follows Kirchhoff hypothesis and thus reduces the 3D magneto-elastic energy function to a one-dimensional(1D)form.Besides,the co-rotational formulation is applied to describe rigid body motion,and explicit time integration is adopted for the nonlinear resolution.Moreover,we explore finite bending,post-buckling and twisting of hard-magnetic elastica under external magnetic fields with different directions and amplitudes.Representative examples with various configurations show superior efficiency and accuracy of the model(the difference less than 1%with only a small number of elements)compared to conventional solid element.Our model could be used to guide rational designs on programmable shape morphing of ferromagnetic slender structures.
基金supported by the National Natural Science Foundation of China(Nos.12132005,11772095,12102094)the Foundation from Science and Technology on Reactor System Design Technology Laboratory。
文摘Models to describe the damage and fracture behaviors of the interface between the fuel foil and cladding in UMo/Zr monolithic fuel plates were established and numerically implemented.The effects of the interfacial cohesive strength and cohesive energy on the irradiationinduced thermal-mechanical behaviors of fuel plates were investigated.The results indicated that for heterogeneously irradiated fuel plates:(1)interfacial damage and failure were predicted to be initiated near the fuel foil corner with higher fission densities,accompanied by the formation of a large gap after interface failure,which was consistent with some experimental observations;high tensile stresses in the fuel foil occurred near the edges of the failed interface,attributed to through-thickness cracking of the fuel foil,as found in some post-irradiation examinations;(2)the cohesive strength and cohesive energy of the interface both influenced the in-pile evolution behaviors of fuel plates;a lower cohesive strength or cohesive energy resulted in faster interfacial damage;(3)after interface fracture,the thickness of the whole plate increased to a greater degree(by~20%)than that of the samples without interfacial damage,which was attributed to the locally enhanced Mises stresses and the nearby creep deformations around the cracked interface.This study provided a theoretical basis for assessing failure in fuel elements.
文摘Cloud computing describes highly scalable computing resources provided as an external service via the internet. Economically, the main feature of cloud computing is that customers only use what they need, and only pay for what they actually use. Resources are available to be accessed from the cloud at any time, and from any location via the internet. There’s no need to worry about how things are being maintained behind the scenes—you simply purchase the IT service you require. This new, web-based generation of computing utilizes remote servers for data storage and management. One of the challenging issues tackled in the cloud computing is the security of data stored in the service providers’ site. In this paper, we propose a new architecture for secure data storage in such a way that users’ data are encrypted and split into various cipher blocks and distributed among different service providers site rather than solely depend on single provider for data storage. This architecture ensures better reliability, availability, scalability and security.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11705256,11772095,and 11572091)the National Key Research and Development Program of China(Grant No.2016YFB0700103)
文摘Granular packings under gravity in frictional and frictionless silos were simulated and the influence of the wall friction on the normal force distribution was investigated. Although there is an obvious Janssen effect in frictional silos, only a slight influence on the geometry of packing was found. The law of normal force distribution is different for frictional and frictionless walls, which is related to the pressure profile. A modified formula with consideration of the pressure profile was well fitted to the simulation results.
基金Corresponding au-thor:Ayman El Shenawy received the Ph.D.degree in systems and computer engineer-ing from Al-Azhar University,Egypt in 2013.He is currently working as a lecturer at Systems and Computers Engineering Department,Faculty of Engineering Al-Azhar University,Egypt.He already de-veloped some breakthrough research in the mentioned areas.He made significant con-tributions to the stated research fields.His research interests include artificial intelligent methods,robotics and machine learning.E-mail:eaymanelshenawy@azhar.edu.eg ORCID iD:0000-0002-1309-644。
文摘The multi-robot systems(MRS)exploration and fire searching problem is an important application of mobile robots which require massive computation capability that exceeds the ability of traditional MRS′s.This paper propose a cloud-based hybrid decentralized partially observable semi-Markov decision process(HDec-POSMDPs)model.The proposed model is implemented for MRS exploration and fire searching application based on the Internet of things(IoT)cloud robotics framework.In this implementation the heavy and expensive computational tasks are offloaded to the cloud servers.The proposed model achieves a significant improvement in the computation burden of the whole task relative to a traditional MRS.The proposed model is applied to explore and search for fire objects in an unknown environment;using different sets of robots sizes.The preliminary evaluation of this implementation demonstrates that as the parallelism of computational instances increase the delay of new actuation commands which will be decreased,the mean time of task completion is decreased,the number of turns in the path from the start pose cells to the target cells is minimized and the energy consumption for each robot is reduced.
基金supports from the National Natural Science Foundation of China (Nos.12132005,12102094 and 12135008)the Shanghai Sailing Program (21YF1402200)the foundation from the Science and Technology on Reactor System Design Technology Laboratory.
文摘A finite-strain homogenization creep model for composite fuels under irradiation conditions is developed and verified,with the irradiation creep strains of the fuel particles and matrix correlated to the macroscale creep responses,excluding the contributions of volumetric strain induced by the irradiation swelling deformations of fuel particles.A finite element(FE)modeling method for uniaxial tensile creep tests is established with the irradiation effects of nuclear materials taken into account.The proposed models and simulation strategy are numerically implemented to a kind of composite nuclear fuel,and the predicted mesoscale creep behaviors and the macroscale creep responses are investigated.The research results indicate that:(1)the macroscale creep responses and the mesoscale stress and strain fields are all greatly affected by the irradiation swelling of fuel particles,owing to the strengthened mechanical interactions between the fuel particles and the matrix.(2)The effective creep rates for a certain case are approximately two constants before and after the critical fission density,which results from the accelerated fission gas swelling after fuel grain recrystallization,and the effects of macroscale tensile stress will be more enhanced at higher temperatures.(3)The macroscale creep contributions from the fuel particles and matrix depend mainly on the current volume fractions varying with fission density.(4)As a function of the macroscale stress,temperature,initial particle volume fraction and particle fission rate,a multi-variable mathematical model for effective creep rates is fitted out for the considered composite fuels,which matches well with the FE predictions.This study supplies important theoretical models and research methods for the multi-scale creep behaviors of various composite fuels and provides a basis for simulation of the thermal–mechanical behavior in related composite fuel elements and assemblies.
基金supported by the National Natural Science Foundation of China(Nos.11872151,11372075,and 91330112)。
文摘A high resolution upwind compact streamfunction numerical algorithm for two-dimensional(2D)double-diffusive convection(DDC)is developed.The unsteady Navier-Stokes(N-S)equations in the streamfunction-velocity form and the scalar temperature and concentration equations are used.An optimized third-order upwind compact(UCD3 opt)scheme with a low dispersion error for the first derivatives is utilized to approximate the third derivatives of the streamfunction in the advection terms of the N-S equations and the first derivatives in the advection terms of the scalar temperature and concentration equations.The remaining first derivatives of the streamfunction(velocity),temperature,and concentration variables used in the governing equations are discretized by the fourth-order compact Pade(SCD4)schemes.With the temperature and concentration variables and their approximate values of the first derivatives obtained by the SCD4 schemes,the explicit fourth-order compact schemes are suggested to approximate the second derivatives of temperature and concentration in the diffusion terms of the energy and concentration equations.The discretization of the temporal term is executed with the second-order Crank-Nicolson(C-N)scheme.To assess the spatial behavior capability of the established numerical algorithm and verify the developed computer code,the DDC flow is numerically solved.The obtained results agree well with the benchmark solutions and some accurate results available in the literature,verifying the accuracy,effectiveness,and robustness of the provided algorithm.Finally,a preliminary application of the proposed method to the DDC is carried out.
文摘One of the most common kinds of cancer is breast cancer.The early detection of it may help lower its overall rates of mortality.In this paper,we robustly propose a novel approach for detecting and classifying breast cancer regions in thermal images.The proposed approach starts with data preprocessing the input images and segmenting the significant regions of interest.In addition,to properly train the machine learning models,data augmentation is applied to increase the number of segmented regions using various scaling ratios.On the other hand,to extract the relevant features from the breast cancer cases,a set of deep neural networks(VGGNet,ResNet-50,AlexNet,and GoogLeNet)are employed.The resulting set of features is processed using the binary dipper throated algorithm to select the most effective features that can realize high classification accuracy.The selected features are used to train a neural network to finally classify the thermal images of breast cancer.To achieve accurate classification,the parameters of the employed neural network are optimized using the continuous dipper throated optimization algorithm.Experimental results show the effectiveness of the proposed approach in classifying the breast cancer cases when compared to other recent approaches in the literature.Moreover,several experiments were conducted to compare the performance of the proposed approach with the other approaches.The results of these experiments emphasized the superiority of the proposed approach.
基金This study was supported by the Royal Society Research Grant(reference code:RGS/R2/212,280)Swansea University IMPACT–Green Recovery funding.Matthew Bedding-Tyrrell is supported by EPSRC–Doctoral Training Partnership(DTP)scholarship(reference code:EP/T517987/1-2573181)。
文摘Mechanical stimulation,such as fluid-induced wall shear stress(WSS),is known that can influence the cellular behaviours.Therefore,in some tissue engineering experiments in vitro,mechanical stimulation is applied via bioreactors to the cells in cell culturing to study cell physiology and pathology.In 3D cell culturing,porous scaffolds are used for housing the cells.It is known that the scaffold porous geometries can influence the scaffold permeability and internal WSS in a bioreactor(such as perfusion bioreactor).To calculate the WSS generated on cells within scaffolds,usually computational fluid dynamics(CFD)simulation is needed.However,the limitations of the computational method for WSS calculation are:(i)the high time cost of the CFD simulation(in particular for the highly irregular geometries);(ii)accessibility to the CFD model for some cell culturing experimentalists due to the knowledge gap.To address these limitations,this study aims to develop an empirical model for calculating the WSS based on scaffold permeability.This model can allow the tissue engineers to efficiently calculate the WSS generated within the scaffold and/or determine the bioreactor loading without performing the computational simulations.
基金supported by the National Natural Science Foundation of China(Grant Nos.11872150,11772094,and 11890673)the Shanghai Rising-Star Program(Grant No.19QA1400500),the Shanghai Chenguang Program(Grant No.16CG01)the State Key Laboratory for Strength and Vibration of Mechanical Structures(Grant No.SV2018-KF-17)。
文摘Surface instability of compliant film/substrate bilayers has raised considerable interests due to its broad applications such as wrinkle-driven surface renewal and antifouling,shape-morphing for camouflaging skins,and micro/nano-scale surface patterning control.However,it is still a challenge to precisely predict and continuously trace secondary bifurcation transitions in the nonlinear post-buckling region.Here,we develop lattice models to precisely capture the nonlinear morphology evolution with multiple mode transitions that occur in the film/substrate systems.Based on our models,we reveal an intricate post-buckling phenomenon involving successive flat-wrinkle-doubling-quadrupling-fold bifurcations.Pre-stretch and pre-compression of the substrate,as well as bilayer modulus ratio,can alter surface morphology of film/substrate bilayers.With high substrate pre-tension,hierarchical wrinkles emerge in the bilayer with a low modulus ratio,while a wrinkle-to-ridge transition occurs with a high modulus ratio.Besides,with moderate substrate pre-compression,the bilayer eventually evolves into a period-tripling mode.Phase diagrams based on neo-Hookean and Arruda-Boyce constitutions are drawn to characterize the influences of different factors and to provide an overall view of ultimate pattern formation.Fundamental understanding and quantitative prediction of the nonlinear morphological transitions of soft bilayer materials hold potential for multifunctional surface regulation.
基金supported by the National Key R&D Program of China (2016YFA0203302)the National Natural Science Foundation of China (21634003, 51573027, 51673043, 21604012, 21805044, 21875042, 11602058, and 11872150)+3 种基金Shanghai Science and Technology Committee (16JC1400702, 17QA1400400, 18QA1400700, and 18QA1400800)Shanghai Municipal Education Commission (2017-01-07-00-07-E00062)Shanghai Chenguang Program (16CG01)Yanchang Petroleum Group
文摘Mechanoluminescence has attracted increasing attentions because it can convert the kinetic energy during human daily motions into light to be used in sensors and displays. However, its practical applications are still hindered by the weak brightness and limited color while under large forces. Herein, we developed novel piezoluminescent devices(PLDs) which could effectively emit visible light under low pressing forces through the stress-concentration and enhancing deformation on the basis of carefully-designed array structures. The emitting colors were also tunable by using bilayer luminescent film under different pressures. This work not only provides a new strategy to effectively harvest mechanical energy into light,but also presents a scalable, low-cost and color-tunable PLD which shows great potentials in various applications such as luminescent floors, shoes and stress-activated displays.
