This study investigates the dynamical behavior of two parallel fluid-conveying pipes by developing a non-planar dynamical model of the two pipes coupled with an intermediate spring. A systematic analysis is conducted ...This study investigates the dynamical behavior of two parallel fluid-conveying pipes by developing a non-planar dynamical model of the two pipes coupled with an intermediate spring. A systematic analysis is conducted to evaluate the effects of spring parameters on the non-planar vibration characteristics and buckling behaviors of the coupled system. The nonlinear governing equations are derived with Hamilton's principle,subsequently discretized through Galerkin's method, and finally numerically solved by the Runge-Kutta algorithm. Based on the linearized equations, an eigenvalue analysis is performed to obtain the coupled frequencies, modal shapes, and critical flow velocities for buckling instability. Quantitative assessments further elucidate the effects of the spring position and stiffness coefficient on the coupled frequencies and critical flow velocities.Nonlinear dynamic analyses reveal the evolution of buckling patterns and bifurcation behaviors between the lateral displacements of the two pipes and the flow velocity. Numerical results indicate that the intermediate spring increases the susceptibility to buckling instability in the out-of-plane direction compared with the in-plane direction. Furthermore, synchronized lateral displacements emerge in both pipes when the flow velocity of one pipe exceeds the critical threshold. This work is expected to provide a theoretical foundation for the stability assessment and vibration analysis in coupled fluid-conveying pipe systems.展开更多
Purpose–This study aimed to facilitate a rapid evaluation of track service status and vehicle ride comfort based on car body acceleration.Consequently,a low-cost,data-driven approach was proposed for analyzing speed-...Purpose–This study aimed to facilitate a rapid evaluation of track service status and vehicle ride comfort based on car body acceleration.Consequently,a low-cost,data-driven approach was proposed for analyzing speed-related acceleration limits in metro systems.Design/methodology/approach–A portable sensing terminal was developed to realize easy and efficient detection of car body acceleration.Further,field measurements were performed on a 51.95-km metro line.Data from 272 metro sections were tested as a case study,and a quantile regression method was proposed to fit the control limits of the car body acceleration at different speeds using the measured data.Findings–First,the frequency statistics of the measured data in the speed-acceleration dimension indicated that the car body acceleration was primarily concentrated within the constant speed stage,particularly at speeds of 15.4,18.3,and 20.9 m/s.Second,resampling was performed according to the probability density distribution of car body acceleration for different speed domains to achieve data balance.Finally,combined with the traditional linear relationship between speed and acceleration,the statistical relationships between the speed and car body acceleration under different quantiles were determined.We concluded the lateral/vertical quantiles of 0.8989/0.9895,0.9942/0.997,and 0.9998/0.993 as being excellent,good,and qualified control limits,respectively,for the lateral and vertical acceleration of the car body.In addition,regression lines for the speedrelated acceleration limits at other quantiles(0.5,0.75,2s,and 3s)were obtained.Originality/value–The proposed method is expected to serve as a reference for further studies on speedrelated acceleration limits in rail transit systems.展开更多
Based on the traditional re-entrant honeycomb,a novel re-entrant octagon honeycomb(ROH)is proposed.The deformation mode of the honeycomb under quasi-static compression is analyzed by numerical simulation,and the resul...Based on the traditional re-entrant honeycomb,a novel re-entrant octagon honeycomb(ROH)is proposed.The deformation mode of the honeycomb under quasi-static compression is analyzed by numerical simulation,and the results are in good agreement with the experimental ones.The deformation modes,mechanical properties,and energy absorption characteristics of ROH along the impact and perpendicular directions gradient design are investigated under different velocities.The results indicated that the deformation mode of ROH is affected by gradient design along the direction of impact and impact speed.In addition,gradient design along the direction of impact can increase the initial peak stress of ROH and accelerate its densification phase.Gradient design perpendicular to the impact direction can enhance the energy absorption performance of ROH,especially for ROH,with wall thickness increasing from the inside outwards.Compared to ROH with uniform wall thickness at the same relative density,ROH with a gradient design can increase the plateau stress by over half.With the elevation of impact velocity,the plateau stress and specific energy absorption exhibit an upward trend,aligning with the dynamic performance pattern observed in conventional honeycombs.The results can be used as a reference for the design and application of honeycomb and provide a new idea for developing more efficient and reliable energy-absorbing materials.展开更多
Natural convection is a heat transfer mechanism driven by temperature or density differences,leading to fluid motion without external influence.It occurs in various natural and engineering phenomena,influencing heat t...Natural convection is a heat transfer mechanism driven by temperature or density differences,leading to fluid motion without external influence.It occurs in various natural and engineering phenomena,influencing heat transfer,climate,and fluid mixing in industrial processes.This work aims to use the Updated Lagrangian Particle Hydrodynamics(ULPH)theory to address natural convection problems.The Navier-Stokes equation is discretized using second-order nonlocal differential operators,allowing a direct solution of the Laplace operator for temperature in the energy equation.Various numerical simulations,including cases such as natural convection in square cavities and two concentric cylinders,were conducted to validate the reliability of the model.The results demonstrate that the proposed model exhibits excellent accuracy and performance,providing a promising and effective numerical approach for natural convection problems.展开更多
In this study,a new bond-based peridynamic model is proposed to describe the dynamic properties of ceramics under impact loading.Ceramic materials show pseudo-plastic behavior under certain compressive loadings with h...In this study,a new bond-based peridynamic model is proposed to describe the dynamic properties of ceramics under impact loading.Ceramic materials show pseudo-plastic behavior under certain compressive loadings with high strain-rate,while the characteristic brittleness of the material dominates when it is subjected to tensile loading.In this model,brittle response under tension,softening plasticity under compression and strain-rate effect of ceramics are considered,which makes it possible to accurately capture the overall dynamic process of ceramics.This enables the investigation of the fracture mechanism for ceramic materials,during ballistic impact,in more detail.Furthermore,a bond-force updating algorithm is introduced to perform the numerical simulation and solve the derived equations.The proposed model is then used to analyze the dynamic response of ceramics tiles under impact loading to assess its validity.The results of damage development in ceramic materials are calculated and compared with the experimental results.The simulation results are consistent with the experiments,which indicates that the proposed rate-dependent peridynamic model has the capability to describe damage propagation in ceramics with good accuracy.Finally,based on a comparison between simulation and experimental results,it can be concluded that the damage results are in better agreement with experimental results than non-ordinary state-based peridynamic method.展开更多
Due to the unique deformation characteristics of auxetic materials(Poisson’s ratioμ<0),they have better shock resistance and energy absorption properties than traditional materials.Inspired by the concept of vari...Due to the unique deformation characteristics of auxetic materials(Poisson’s ratioμ<0),they have better shock resistance and energy absorption properties than traditional materials.Inspired by the concept of variable crosssection design,a new auxetic re-entrant honeycomb structure is designed in this study.The detailed design method of re-entrant honeycomb with variable cross-section(VCRH)is provided,and five VCRH structures with the same relative density and different cross-section change rates are proposed.The in-plane impact resistance and energy absorption abilities of VCRH under constant velocity are investigated by ABAQUS/EXPLICIT.The results show that the introduction of variable cross-section design can effectively improve the impact resistance and energy absorption abilities of auxetic re-entrant honeycombs.The VCRH structure has better Young’s modulus,plateau stress,and specific energy absorption(SEA)than traditional re-entrant honeycomb(RH).The influence of microstructure parameters(such as cross-section change rateα)on the dynamic impact performance of VCRH is also studied.Results show that,with the increase in impact velocity andα,the plateau stress and SEA of VCRH increase.A positive correlation is also found between the energy absorption efficiency,impact load uniformity andαunder both medium and high impact speeds.These results can provide a reference for designing improved auxetic re-entrant honeycomb structures.展开更多
A rate-dependent peridynamic ceramic model,considering the brittle tensile response,compressive plastic softening and strain-rate dependence,can accurately represent the dynamic response and crack propagation of ceram...A rate-dependent peridynamic ceramic model,considering the brittle tensile response,compressive plastic softening and strain-rate dependence,can accurately represent the dynamic response and crack propagation of ceramic materials.However,it also considers the strain-rate dependence and damage accumulation caused by compressive plastic softening during the compression stage,requiring more computational resources for the bond force evaluation and damage evolution.Herein,the OpenMP parallel optimization of the rate-dependent peridynamic ceramicmodel is investigated.Also,themodules that compute the interactions betweenmaterial points and update damage index are vectorized and parallelized.Moreover,the numerical examples are carried out to simulate the dynamic response and fracture of the ceramic plate under normal impact.Furthermore,the speed-up ratio and computational efficiency by multi-threads are evaluated and discussed to demonstrate the reliability of parallelized programs.The results reveal that the totalwall clock time has been significantly reduced after optimization,showing the promise of parallelization process in terms of accuracy and stability.展开更多
Hepatocellular carcinoma(HCC)is associated with poor prognosis and fluctuations in immune status.Although studies have found that secreted phosphoprotein 1(SPP1)is involved in HCC progression,its independent prognosti...Hepatocellular carcinoma(HCC)is associated with poor prognosis and fluctuations in immune status.Although studies have found that secreted phosphoprotein 1(SPP1)is involved in HCC progression,its independent prognostic value and immune-mediated role remain unclear.Using The Cancer Genome Atlas and Gene Expression Omnibus data,we found that low expression of SPP1 is significantly associated with improved survival of HCC patients and that SPP1 expression is correlated with clinical characteristics.Univariate and multivariate Cox regression confirmed that SPP1 is an independent prognostic factor of HCC.Subsequently,we found that T cell CD4 memory-activated monocytes,M0 macrophages,and resting mast cells showed significant differences in penetration in the high and low SPP1 expression groups.Next,we used the Weighted Gene Co-Expression Network and Least Absolute Shrinkage Sum Selection Operator algorithms to construct a risk score for the 9-immune-related genes signature.The risk score showed a good ability to identify high and low-risk patients and improved survival prediction.We also used multivariate Cox regression to validate that risk score was significantly correlated with SPP1 and overall survival.Lastly,the Back-Propagation Neural Network confirmed the reliability of the results of multiple algorithms.In conclusion,the findings suggest that SPP1 is an independent marker of HCC survival and immunotherapy.展开更多
There are many forms of tensor theory which are quite different. Discussions are put forward and their relationships are found. The differences between them depend on whether there is metric on the space and the basis...There are many forms of tensor theory which are quite different. Discussions are put forward and their relationships are found. The differences between them depend on whether there is metric on the space and the basis is orthonormal.展开更多
A vein model was established to simulate the periodic characteristics of blood flow and valve deformation in blood-induced valve cycles.Using an immersed finite element method which was modified by a ghost fluid techn...A vein model was established to simulate the periodic characteristics of blood flow and valve deformation in blood-induced valve cycles.Using an immersed finite element method which was modified by a ghost fluid technique,the interaction between the vein and blood was simulated.With an independent solid solver,the contact force between vein tissues was calculated using an adhesive contact method.A benchmark simulation of the normal valve cycle validated the proposed model for a healthy vein.Both the opening orifice and blood flow rate agreed with those in the physiology.Low blood shear stress and maximum leaflet stress were also seen in the base region of the valve.On the basis of the healthy model,a diseased vein model was subsequently built to explore the sinus lesions,namely,fibrosis and atrophy which are assumed stiffening and softening of the sinus.Our results showed the opening orifice of the diseased vein was inversely proportional to the corresponding modulus of the sinus.A drop in the transvalvular pressure gradient resulted from the sinus lesion.Compared to the fibrosis,the atrophy of the sinus apparently improved the vein deformability but simultaneously accelerated the deterioration of venous disease and increased the risk of potential fracture.These results provide understandings of the normal/abnormal valve cycle in vein,and can be also helpful for the prosthesis design.展开更多
Split Hopkinson pressure bar(SHPB)was utilized to explore the effects of loading strain rate on the dynamic compressing strength of the titanium alloy lattice material.Results reveal that the yield strength of alloy l...Split Hopkinson pressure bar(SHPB)was utilized to explore the effects of loading strain rate on the dynamic compressing strength of the titanium alloy lattice material.Results reveal that the yield strength of alloy lattice material reaches 342 MPa initially and then drops to 200 MPa before it rebounds to 252 MPa while the loading strain rate correspondingly increases from the static value 1401/s to 2084/s.Numerical simulations were then carried out to explore the possible reason underlying.Results show that the lattice structure changed the stress distribution and caused significate stress concentration at finite strain with high strain rate.It is believed that the strain rate strengthening effect and layer-wise failure mode are the main reasons of the above mechanical properties change.展开更多
In this work,wemodeled the brittle fracture of shell structure in the framework of Peridynamics Mindlin-Reissener shell theory,in which the shell is described by material points in themean-plane with its drilling rota...In this work,wemodeled the brittle fracture of shell structure in the framework of Peridynamics Mindlin-Reissener shell theory,in which the shell is described by material points in themean-plane with its drilling rotation neglected in kinematic assumption.To improve the numerical accuracy,the stress-point method is utilized to eliminate the numerical instability induced by the zero-energy mode and rank-deficiency.The crack surface is represented explicitly by stress points,and a novel general crack criterion is proposed based on that.Instead of the critical stretch used in common peridynamic solid,it is convenient to describe thematerial failure by using the classic constitutive model in continuum mechanics.In this work,a concise crack simulation algorithm is also provided to describe the crack path and its development,in order to simulate the brittle fracture of the shell structure.Numerical examples are presented to validate and demonstrate our proposed model.Results reveal that our model has good accuracy and capability to represent crack propagation and branch spontaneously.展开更多
TIME,Immunity,Prognosis,BioinformaticsThis study used transcriptome and epigenetic data to predict the prognosis of immune-related genes(IRGs)Apelin(APLN)in patients with hepatocellular carcinoma(HCC).The TCGA databas...TIME,Immunity,Prognosis,BioinformaticsThis study used transcriptome and epigenetic data to predict the prognosis of immune-related genes(IRGs)Apelin(APLN)in patients with hepatocellular carcinoma(HCC).The TCGA database has gene expression and clinical data for HCC.And DNA methylation 450 k data for HCC was download from the University of California Santa Cruz(UCSC)Xena browser.Performing clinical and prognostic analysis of APLN expression,results show that APLN is highly expressed in tumor samples.And it has an increasing trend with the development of clinical stage and T stage.To explore the prognostic role of APLN,the Immune-related DNA methylation(DNAm)sites associated with APLN analyzed by bioinformatics.Univariate COX screened the methylation sites that are related to both APLN and survival.The risk score related to methylation site signature was determined according to their least absolute shrinkage and selection operator(LASSO)coefficients.Then the patients were divided into high-risk groups and low-risk groups.Significant differences in overall survival(OS)were found in the training cohort.Nomogram shows that APLN or methylation signature can effectively predict the prognosis of HCC patients.In summary,APLN may be a diagnostic and prognostic marker for HCC.展开更多
Timoshenko beam model is employed to investigate the vibration of atomic force mi- croscope （AFM） cantilevers in contact resonance force microscopy （CRFM）. Characteristic equation with both vertical and lateral ti...Timoshenko beam model is employed to investigate the vibration of atomic force mi- croscope （AFM） cantilevers in contact resonance force microscopy （CRFM）. Characteristic equation with both vertical and lateral tip-sample contact is derived. The contact resonance frequencies （CRFs） obtained by the Timoshenko model are compared with those by the Euler-Bernoulli model. A method is proposed to correct the wave number obtained by the Euler-Bernoulli model. The forced vibration is compared between the two models. Results reveal that the Timoshenko model is superior to the Euler-Bernoulli model in predicting the vibration characteristics for cantilevers＇ higher eigenmodes.展开更多
Fracture in ductile materials often occurs in conjunction with plastic deformation.However,in the bond-based peridynamic(BB-PD)theory,the classic mechanical stress is not defined inherently.This makes it difficult to ...Fracture in ductile materials often occurs in conjunction with plastic deformation.However,in the bond-based peridynamic(BB-PD)theory,the classic mechanical stress is not defined inherently.This makes it difficult to describe plasticity directly using the classical plastic theory.To address the above issue,a unified bond-based peridynamics model was proposed as an effective tool to solve elastoplastic fracture problems.Compared to the existing models,the proposed model directly describes the elastoplastic theory at the bond level without the need for additional calculation means.The results obtained in the context of this model are shown to be consistent with FEM results in regard to force-displacement curves,displacement fields,stress fields,and plastic deformation regions.The model exhibits good capability of capturing crack propagation in ductile material failure problems.展开更多
A fluid-structure interaction approach is proposed in this paper based onNon-Ordinary State-Based Peridynamics(NOSB-PD)and Updated Lagrangian Particle Hydrodynamics(ULPH)to simulate the fluid-structure interaction pro...A fluid-structure interaction approach is proposed in this paper based onNon-Ordinary State-Based Peridynamics(NOSB-PD)and Updated Lagrangian Particle Hydrodynamics(ULPH)to simulate the fluid-structure interaction problem with large geometric deformation and material failure and solve the fluid-structure interaction problem of Newtonian fluid.In the coupled framework,the NOSB-PD theory describes the deformation and fracture of the solid material structure.ULPH is applied to describe the flow of Newtonian fluids due to its advantages in computational accuracy.The framework utilizes the advantages of NOSB-PD theory for solving discontinuous problems and ULPH theory for solving fluid problems,with good computational stability and robustness.A fluidstructure coupling algorithm using pressure as the transmission medium is established to deal with the fluidstructure interface.The dynamic model of solid structure and the PD-ULPH fluid-structure interaction model involving large deformation are verified by numerical simulations.The results agree with the analytical solution,the available experimental data,and other numerical results.Thus,the accuracy and effectiveness of the proposed method in solving the fluid-structure interaction problem are demonstrated.The fluid-structure interactionmodel based on ULPH and NOSB-PD established in this paper provides a new idea for the numerical solution of fluidstructure interaction and a promising approach for engineering design and experimental prediction.展开更多
The ablation of ultra-high-temperature ceramics(UTHCs)is a complex physicochemical process including mechanical behavior,temperature effect,and chemical reactions.In order to realize the structural optimization and fu...The ablation of ultra-high-temperature ceramics(UTHCs)is a complex physicochemical process including mechanical behavior,temperature effect,and chemical reactions.In order to realize the structural optimization and functional design of ultra-high temperature ceramics,a coupled thermo-chemo-mechanical bond-based peridynamics(PD)model is proposed based on the ZrB_(2) ceramics oxidation kinetics model and coupled thermomechanical bond-based peridynamics.Compared with the traditional coupled thermo-mechanical model,the proposedmodel considers the influenceof chemical reactionprocessonthe ablation resistanceof ceramicmaterials.In order to verify the reliability of the proposed model,the thermo-mechanical coupling model,damage model and oxidation kinetic model are established respectively to investigate the applicability of the proposedmodel proposed in dealing with thermo-mechanical coupling,crack propagation,and chemical reaction,and the results show that the model is reliable.Finally,the coupled thermo-mechanical model and coupled thermo-chemo-mechanical model are used to simulate the crack propagation process of the plate under the thermal shock load,and the results show that the oxide layer plays a good role in preventing heat transfer and protecting the internal materials.Based on the PD fully coupled thermo-mechanical model,this paper innovatively introduces the oxidation kinetic model to analyze the influence of parameter changes caused by oxide layer growth and chemical growth strain on the thermal protection ability of ceramics.The proposed model provides an effective simulation technology for the structural design of UTHCs.展开更多
Diabetic nephropathy(DN)is a common microvascular complication that easily leads to end-stage renal disease.It is important to explore the key biomarkers andmolecular mechanisms relevant to diabetic nephropathy(DN).We...Diabetic nephropathy(DN)is a common microvascular complication that easily leads to end-stage renal disease.It is important to explore the key biomarkers andmolecular mechanisms relevant to diabetic nephropathy(DN).We used highthroughput RNA sequencing to obtain the genes related to DN glomerular tissues and healthy glomerular tissues of mice.Then we used LIMMA to analyze differentially expressed genes(DEGs)between DN and non-diabetic glomerular samples.And we performed KEGG,gene ontology functional(GO)enrichment,and gene set enrichment analysis to reveal the signaling pathway of the disease.The CIBERSORT algorithm based on support vector machine was used to determine the immune infiltration score.Random forest algorithm and Cytoscape obtained hub genes.Finally,we applied co-staining,immunohistochemical staining,RT-qPCR and western blotting to validate the protein and mRNA expression of both hub genes.We obtained 913 DEGs mainly related to inflammatory factors and immunity.GSEA results showed that differential genes were mainly enriched in IL-17 signaling pathway,lipid and atherosclerosis,rheumatoid arthritis,TNF signaling pathway,neutrophil extracellular trap formation,Staphylococcus aureus infection and other pathways.The intersection of the random forest algorithm and Cytoscape revealed both hub genes of CD300A and CXCL1.Experiments have shown that the both key genes of CD300A and CXCL1 shown increased expression in glomerular podocytes,and are related to the inflammation of diabetic nephropathy.And immunohistochemical staining and RT-qPCR further confirmed that the protein and mRNA expression level of CD300A or CXCL1 in glomeruli tissue in DN mice were increased.The expression levels of CD300A and CXCL1 increased significantly under HG(high glucose)stimulation,further confirming that diabetes can lead to increased levels of CD300A and CXCL1 at the cellular level.Through bioinformatics analysis,machine learning algorithms,and experimental research,CD300A and CXCL1 are confirmed as both potential biomarkers in diabetic nephropathy.And we further revealed the main pathways of differential genes and the differentially distributed immune infiltrating cells in diabetic nephropathy.展开更多
There is currently no effective solution to the problem of poor prognosis and recurrence of HCC.The technology of immunotherapy and prognosis of genetic material has made continuous progress in recent years.In the stu...There is currently no effective solution to the problem of poor prognosis and recurrence of HCC.The technology of immunotherapy and prognosis of genetic material has made continuous progress in recent years.In the study,a 5-gene signature was established for the prognosis of HCC through biological information,and the immune infiltration of HCC patients was studied.After studied HCC patients’immune infiltration,the paper screened the differential target genes of miR-126-3p in HCC downloaded from TCGA database,and uses WGCNA method to select the modular genes highly relevant to M2 macrophage.Then we use LASSO and COX regression analysis technology to establish the 5-gene signature.The nomogram is established by combining the prognostic score and clinical phenotype.Cibersort was empolyed to observe the immune infiltration in HCC patients.We revealed the biological pathways of HCC-related genes through GSEA and Metascape.The bioinformatics analysis of 2495 differential target genes finally constructed a 5-gene signature with a reliable prognostic ability(CDCA8,SLC41A3,PPM1G,TCOF1,GRPEL2).The combination of prognostic score and AJCC_Stage resulted in a more reliable prognosis ability.At the same time,10 immune cells that are differentially expressed in HCC patients were also found.8 GSEA pathways related to the prognosis were found.In the study,a reliable 5-gene signature was established based on the differential target gene of miR-126-3p to study the immune infiltration in HCC patients.It provides help for HCC-related prognosis research and immunotherapy.展开更多
The quality of parts manufactured by laser powder bed fusion is closely related to the uniformity and density of the powder bed.In this work,the discrete element method is used to simulate the powder spreading process...The quality of parts manufactured by laser powder bed fusion is closely related to the uniformity and density of the powder bed.In this work,the discrete element method is used to simulate the powder spreading process by different spreader geometries with rough substrate surfaces.The results indicate that reducing the spreader inclination angle significantly increases the number of force chains,enhances compaction,and consequently improves the quality of the powder bed.Studies also show that optimizing the bottom structure of the spreader can effectively reduce exposed areas.An arc-shaped structure promotes particle packing and filling,improving the powder distribution characteristics.A narrow spreader significantly affects the packing density of the powder bed at low layer gaps,whereas a wide spreader is relatively less constrained.At high spreading speeds,the spreader with an inclination angle of 135°produces the highest quality of the powder bed.R1000 performs excellently at larger layer gaps.The above findings provide valuable guidance for optimizing powder spreading strategies in the laser powder bed fusion process.展开更多
基金supported by the National Natural Science Foundation of China(Nos.12325201,12272140,and 12322201)。
文摘This study investigates the dynamical behavior of two parallel fluid-conveying pipes by developing a non-planar dynamical model of the two pipes coupled with an intermediate spring. A systematic analysis is conducted to evaluate the effects of spring parameters on the non-planar vibration characteristics and buckling behaviors of the coupled system. The nonlinear governing equations are derived with Hamilton's principle,subsequently discretized through Galerkin's method, and finally numerically solved by the Runge-Kutta algorithm. Based on the linearized equations, an eigenvalue analysis is performed to obtain the coupled frequencies, modal shapes, and critical flow velocities for buckling instability. Quantitative assessments further elucidate the effects of the spring position and stiffness coefficient on the coupled frequencies and critical flow velocities.Nonlinear dynamic analyses reveal the evolution of buckling patterns and bifurcation behaviors between the lateral displacements of the two pipes and the flow velocity. Numerical results indicate that the intermediate spring increases the susceptibility to buckling instability in the out-of-plane direction compared with the in-plane direction. Furthermore, synchronized lateral displacements emerge in both pipes when the flow velocity of one pipe exceeds the critical threshold. This work is expected to provide a theoretical foundation for the stability assessment and vibration analysis in coupled fluid-conveying pipe systems.
基金the National Natural Science Foundation of China(NSFC)under No.52308473the National KeyR&DProgram under No.2022YFB2603301the China Postdoctoral Science Foundation funded project(Certificate Number:2023M743895).
文摘Purpose–This study aimed to facilitate a rapid evaluation of track service status and vehicle ride comfort based on car body acceleration.Consequently,a low-cost,data-driven approach was proposed for analyzing speed-related acceleration limits in metro systems.Design/methodology/approach–A portable sensing terminal was developed to realize easy and efficient detection of car body acceleration.Further,field measurements were performed on a 51.95-km metro line.Data from 272 metro sections were tested as a case study,and a quantile regression method was proposed to fit the control limits of the car body acceleration at different speeds using the measured data.Findings–First,the frequency statistics of the measured data in the speed-acceleration dimension indicated that the car body acceleration was primarily concentrated within the constant speed stage,particularly at speeds of 15.4,18.3,and 20.9 m/s.Second,resampling was performed according to the probability density distribution of car body acceleration for different speed domains to achieve data balance.Finally,combined with the traditional linear relationship between speed and acceleration,the statistical relationships between the speed and car body acceleration under different quantiles were determined.We concluded the lateral/vertical quantiles of 0.8989/0.9895,0.9942/0.997,and 0.9998/0.993 as being excellent,good,and qualified control limits,respectively,for the lateral and vertical acceleration of the car body.In addition,regression lines for the speedrelated acceleration limits at other quantiles(0.5,0.75,2s,and 3s)were obtained.Originality/value–The proposed method is expected to serve as a reference for further studies on speedrelated acceleration limits in rail transit systems.
基金This work is supported by the National Natural Science Foundation of China(No.11902232).
文摘Based on the traditional re-entrant honeycomb,a novel re-entrant octagon honeycomb(ROH)is proposed.The deformation mode of the honeycomb under quasi-static compression is analyzed by numerical simulation,and the results are in good agreement with the experimental ones.The deformation modes,mechanical properties,and energy absorption characteristics of ROH along the impact and perpendicular directions gradient design are investigated under different velocities.The results indicated that the deformation mode of ROH is affected by gradient design along the direction of impact and impact speed.In addition,gradient design along the direction of impact can increase the initial peak stress of ROH and accelerate its densification phase.Gradient design perpendicular to the impact direction can enhance the energy absorption performance of ROH,especially for ROH,with wall thickness increasing from the inside outwards.Compared to ROH with uniform wall thickness at the same relative density,ROH with a gradient design can increase the plateau stress by over half.With the elevation of impact velocity,the plateau stress and specific energy absorption exhibit an upward trend,aligning with the dynamic performance pattern observed in conventional honeycombs.The results can be used as a reference for the design and application of honeycomb and provide a new idea for developing more efficient and reliable energy-absorbing materials.
基金support from the National Natural Science Foundations of China(Nos.11972267 and 11802214)the Open Foundation of the Hubei Key Laboratory of Theory and Application of Advanced Materials Mechanics and the Open Foundation of Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment.
文摘Natural convection is a heat transfer mechanism driven by temperature or density differences,leading to fluid motion without external influence.It occurs in various natural and engineering phenomena,influencing heat transfer,climate,and fluid mixing in industrial processes.This work aims to use the Updated Lagrangian Particle Hydrodynamics(ULPH)theory to address natural convection problems.The Navier-Stokes equation is discretized using second-order nonlocal differential operators,allowing a direct solution of the Laplace operator for temperature in the energy equation.Various numerical simulations,including cases such as natural convection in square cavities and two concentric cylinders,were conducted to validate the reliability of the model.The results demonstrate that the proposed model exhibits excellent accuracy and performance,providing a promising and effective numerical approach for natural convection problems.
基金supported by the National Natural Science Foundation of China(Nos.11972267 and 11802214)the Fundamental Research Funds for the Central Universities(WUT:2018IB006 and WUT:2019IVB042).
文摘In this study,a new bond-based peridynamic model is proposed to describe the dynamic properties of ceramics under impact loading.Ceramic materials show pseudo-plastic behavior under certain compressive loadings with high strain-rate,while the characteristic brittleness of the material dominates when it is subjected to tensile loading.In this model,brittle response under tension,softening plasticity under compression and strain-rate effect of ceramics are considered,which makes it possible to accurately capture the overall dynamic process of ceramics.This enables the investigation of the fracture mechanism for ceramic materials,during ballistic impact,in more detail.Furthermore,a bond-force updating algorithm is introduced to perform the numerical simulation and solve the derived equations.The proposed model is then used to analyze the dynamic response of ceramics tiles under impact loading to assess its validity.The results of damage development in ceramic materials are calculated and compared with the experimental results.The simulation results are consistent with the experiments,which indicates that the proposed rate-dependent peridynamic model has the capability to describe damage propagation in ceramics with good accuracy.Finally,based on a comparison between simulation and experimental results,it can be concluded that the damage results are in better agreement with experimental results than non-ordinary state-based peridynamic method.
基金This research is supported by the National Natural Science Foundation of China(No.11902232).
文摘Due to the unique deformation characteristics of auxetic materials(Poisson’s ratioμ<0),they have better shock resistance and energy absorption properties than traditional materials.Inspired by the concept of variable crosssection design,a new auxetic re-entrant honeycomb structure is designed in this study.The detailed design method of re-entrant honeycomb with variable cross-section(VCRH)is provided,and five VCRH structures with the same relative density and different cross-section change rates are proposed.The in-plane impact resistance and energy absorption abilities of VCRH under constant velocity are investigated by ABAQUS/EXPLICIT.The results show that the introduction of variable cross-section design can effectively improve the impact resistance and energy absorption abilities of auxetic re-entrant honeycombs.The VCRH structure has better Young’s modulus,plateau stress,and specific energy absorption(SEA)than traditional re-entrant honeycomb(RH).The influence of microstructure parameters(such as cross-section change rateα)on the dynamic impact performance of VCRH is also studied.Results show that,with the increase in impact velocity andα,the plateau stress and SEA of VCRH increase.A positive correlation is also found between the energy absorption efficiency,impact load uniformity andαunder both medium and high impact speeds.These results can provide a reference for designing improved auxetic re-entrant honeycomb structures.
基金supported by the National Natural Science Foundation of China(Nos.11972267,11802214 and 51932006)the Fundamental Research Funds for the Central Universities(WUT:2020lll031GX).
文摘A rate-dependent peridynamic ceramic model,considering the brittle tensile response,compressive plastic softening and strain-rate dependence,can accurately represent the dynamic response and crack propagation of ceramic materials.However,it also considers the strain-rate dependence and damage accumulation caused by compressive plastic softening during the compression stage,requiring more computational resources for the bond force evaluation and damage evolution.Herein,the OpenMP parallel optimization of the rate-dependent peridynamic ceramicmodel is investigated.Also,themodules that compute the interactions betweenmaterial points and update damage index are vectorized and parallelized.Moreover,the numerical examples are carried out to simulate the dynamic response and fracture of the ceramic plate under normal impact.Furthermore,the speed-up ratio and computational efficiency by multi-threads are evaluated and discussed to demonstrate the reliability of parallelized programs.The results reveal that the totalwall clock time has been significantly reduced after optimization,showing the promise of parallelization process in terms of accuracy and stability.
基金supported by Hubei Provincial Key Laboratory Opening Project of Renmin Hospital of Wuhan University(2022KFH010).
文摘Hepatocellular carcinoma(HCC)is associated with poor prognosis and fluctuations in immune status.Although studies have found that secreted phosphoprotein 1(SPP1)is involved in HCC progression,its independent prognostic value and immune-mediated role remain unclear.Using The Cancer Genome Atlas and Gene Expression Omnibus data,we found that low expression of SPP1 is significantly associated with improved survival of HCC patients and that SPP1 expression is correlated with clinical characteristics.Univariate and multivariate Cox regression confirmed that SPP1 is an independent prognostic factor of HCC.Subsequently,we found that T cell CD4 memory-activated monocytes,M0 macrophages,and resting mast cells showed significant differences in penetration in the high and low SPP1 expression groups.Next,we used the Weighted Gene Co-Expression Network and Least Absolute Shrinkage Sum Selection Operator algorithms to construct a risk score for the 9-immune-related genes signature.The risk score showed a good ability to identify high and low-risk patients and improved survival prediction.We also used multivariate Cox regression to validate that risk score was significantly correlated with SPP1 and overall survival.Lastly,the Back-Propagation Neural Network confirmed the reliability of the results of multiple algorithms.In conclusion,the findings suggest that SPP1 is an independent marker of HCC survival and immunotherapy.
基金Sponsored by the National Natural Science Foundation of China(10372074)
文摘There are many forms of tensor theory which are quite different. Discussions are put forward and their relationships are found. The differences between them depend on whether there is metric on the space and the basis is orthonormal.
基金by Key Aviation Scientific and Technological Laboratory of High-speed Hydrodynamic under grant MJ-2015-F-028.
文摘A vein model was established to simulate the periodic characteristics of blood flow and valve deformation in blood-induced valve cycles.Using an immersed finite element method which was modified by a ghost fluid technique,the interaction between the vein and blood was simulated.With an independent solid solver,the contact force between vein tissues was calculated using an adhesive contact method.A benchmark simulation of the normal valve cycle validated the proposed model for a healthy vein.Both the opening orifice and blood flow rate agreed with those in the physiology.Low blood shear stress and maximum leaflet stress were also seen in the base region of the valve.On the basis of the healthy model,a diseased vein model was subsequently built to explore the sinus lesions,namely,fibrosis and atrophy which are assumed stiffening and softening of the sinus.Our results showed the opening orifice of the diseased vein was inversely proportional to the corresponding modulus of the sinus.A drop in the transvalvular pressure gradient resulted from the sinus lesion.Compared to the fibrosis,the atrophy of the sinus apparently improved the vein deformability but simultaneously accelerated the deterioration of venous disease and increased the risk of potential fracture.These results provide understandings of the normal/abnormal valve cycle in vein,and can be also helpful for the prosthesis design.
文摘Split Hopkinson pressure bar(SHPB)was utilized to explore the effects of loading strain rate on the dynamic compressing strength of the titanium alloy lattice material.Results reveal that the yield strength of alloy lattice material reaches 342 MPa initially and then drops to 200 MPa before it rebounds to 252 MPa while the loading strain rate correspondingly increases from the static value 1401/s to 2084/s.Numerical simulations were then carried out to explore the possible reason underlying.Results show that the lattice structure changed the stress distribution and caused significate stress concentration at finite strain with high strain rate.It is believed that the strain rate strengthening effect and layer-wise failure mode are the main reasons of the above mechanical properties change.
基金The authors would like to express grateful acknowledgement to the support from National Natural Science Foundation of China(Nos.11802214 and 11972267)the Fundamental Research Funds for the Central Universities(WUT:2018IB006 and WUT:2019IVB042).
文摘In this work,wemodeled the brittle fracture of shell structure in the framework of Peridynamics Mindlin-Reissener shell theory,in which the shell is described by material points in themean-plane with its drilling rotation neglected in kinematic assumption.To improve the numerical accuracy,the stress-point method is utilized to eliminate the numerical instability induced by the zero-energy mode and rank-deficiency.The crack surface is represented explicitly by stress points,and a novel general crack criterion is proposed based on that.Instead of the critical stretch used in common peridynamic solid,it is convenient to describe thematerial failure by using the classic constitutive model in continuum mechanics.In this work,a concise crack simulation algorithm is also provided to describe the crack path and its development,in order to simulate the brittle fracture of the shell structure.Numerical examples are presented to validate and demonstrate our proposed model.Results reveal that our model has good accuracy and capability to represent crack propagation and branch spontaneously.
基金This work was supported by the Fund of Biosecurity Specialized Project of PLA(No.19SWAQ18).
文摘TIME,Immunity,Prognosis,BioinformaticsThis study used transcriptome and epigenetic data to predict the prognosis of immune-related genes(IRGs)Apelin(APLN)in patients with hepatocellular carcinoma(HCC).The TCGA database has gene expression and clinical data for HCC.And DNA methylation 450 k data for HCC was download from the University of California Santa Cruz(UCSC)Xena browser.Performing clinical and prognostic analysis of APLN expression,results show that APLN is highly expressed in tumor samples.And it has an increasing trend with the development of clinical stage and T stage.To explore the prognostic role of APLN,the Immune-related DNA methylation(DNAm)sites associated with APLN analyzed by bioinformatics.Univariate COX screened the methylation sites that are related to both APLN and survival.The risk score related to methylation site signature was determined according to their least absolute shrinkage and selection operator(LASSO)coefficients.Then the patients were divided into high-risk groups and low-risk groups.Significant differences in overall survival(OS)were found in the training cohort.Nomogram shows that APLN or methylation signature can effectively predict the prognosis of HCC patients.In summary,APLN may be a diagnostic and prognostic marker for HCC.
基金the financial support from National Natural Science Foundation of China under Grant nos.11502182 and 11402182the Fundamental Research Funds for the Central Universities (WUT:2015III025)
文摘Timoshenko beam model is employed to investigate the vibration of atomic force mi- croscope （AFM） cantilevers in contact resonance force microscopy （CRFM）. Characteristic equation with both vertical and lateral tip-sample contact is derived. The contact resonance frequencies （CRFs） obtained by the Timoshenko model are compared with those by the Euler-Bernoulli model. A method is proposed to correct the wave number obtained by the Euler-Bernoulli model. The forced vibration is compared between the two models. Results reveal that the Timoshenko model is superior to the Euler-Bernoulli model in predicting the vibration characteristics for cantilevers＇ higher eigenmodes.
基金The corresponding author Lisheng Liu acknowledges the support from the National Natural Science Foundation of China(No.11972267)The corresponding author Xin Lai acknowledges the support from the National Natural Science Foundation of China(No.11802214).
文摘Fracture in ductile materials often occurs in conjunction with plastic deformation.However,in the bond-based peridynamic(BB-PD)theory,the classic mechanical stress is not defined inherently.This makes it difficult to describe plasticity directly using the classical plastic theory.To address the above issue,a unified bond-based peridynamics model was proposed as an effective tool to solve elastoplastic fracture problems.Compared to the existing models,the proposed model directly describes the elastoplastic theory at the bond level without the need for additional calculation means.The results obtained in the context of this model are shown to be consistent with FEM results in regard to force-displacement curves,displacement fields,stress fields,and plastic deformation regions.The model exhibits good capability of capturing crack propagation in ductile material failure problems.
基金open foundation of the Hubei Key Laboratory of Theory and Application of Advanced Materials Mechanicsthe Open Foundation of Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment.
文摘A fluid-structure interaction approach is proposed in this paper based onNon-Ordinary State-Based Peridynamics(NOSB-PD)and Updated Lagrangian Particle Hydrodynamics(ULPH)to simulate the fluid-structure interaction problem with large geometric deformation and material failure and solve the fluid-structure interaction problem of Newtonian fluid.In the coupled framework,the NOSB-PD theory describes the deformation and fracture of the solid material structure.ULPH is applied to describe the flow of Newtonian fluids due to its advantages in computational accuracy.The framework utilizes the advantages of NOSB-PD theory for solving discontinuous problems and ULPH theory for solving fluid problems,with good computational stability and robustness.A fluidstructure coupling algorithm using pressure as the transmission medium is established to deal with the fluidstructure interface.The dynamic model of solid structure and the PD-ULPH fluid-structure interaction model involving large deformation are verified by numerical simulations.The results agree with the analytical solution,the available experimental data,and other numerical results.Thus,the accuracy and effectiveness of the proposed method in solving the fluid-structure interaction problem are demonstrated.The fluid-structure interactionmodel based on ULPH and NOSB-PD established in this paper provides a new idea for the numerical solution of fluidstructure interaction and a promising approach for engineering design and experimental prediction.
基金support from the National Natural Science Foun-dation of China(11972267).
文摘The ablation of ultra-high-temperature ceramics(UTHCs)is a complex physicochemical process including mechanical behavior,temperature effect,and chemical reactions.In order to realize the structural optimization and functional design of ultra-high temperature ceramics,a coupled thermo-chemo-mechanical bond-based peridynamics(PD)model is proposed based on the ZrB_(2) ceramics oxidation kinetics model and coupled thermomechanical bond-based peridynamics.Compared with the traditional coupled thermo-mechanical model,the proposedmodel considers the influenceof chemical reactionprocessonthe ablation resistanceof ceramicmaterials.In order to verify the reliability of the proposed model,the thermo-mechanical coupling model,damage model and oxidation kinetic model are established respectively to investigate the applicability of the proposedmodel proposed in dealing with thermo-mechanical coupling,crack propagation,and chemical reaction,and the results show that the model is reliable.Finally,the coupled thermo-mechanical model and coupled thermo-chemo-mechanical model are used to simulate the crack propagation process of the plate under the thermal shock load,and the results show that the oxide layer plays a good role in preventing heat transfer and protecting the internal materials.Based on the PD fully coupled thermo-mechanical model,this paper innovatively introduces the oxidation kinetic model to analyze the influence of parameter changes caused by oxide layer growth and chemical growth strain on the thermal protection ability of ceramics.The proposed model provides an effective simulation technology for the structural design of UTHCs.
基金These studies were supported by grants from the National Natural Science Foundation of China(Grant No:81970631 to W.L.)the Fund of Biosecurity Specialized Project of PLA(No.19SWAQ18).
文摘Diabetic nephropathy(DN)is a common microvascular complication that easily leads to end-stage renal disease.It is important to explore the key biomarkers andmolecular mechanisms relevant to diabetic nephropathy(DN).We used highthroughput RNA sequencing to obtain the genes related to DN glomerular tissues and healthy glomerular tissues of mice.Then we used LIMMA to analyze differentially expressed genes(DEGs)between DN and non-diabetic glomerular samples.And we performed KEGG,gene ontology functional(GO)enrichment,and gene set enrichment analysis to reveal the signaling pathway of the disease.The CIBERSORT algorithm based on support vector machine was used to determine the immune infiltration score.Random forest algorithm and Cytoscape obtained hub genes.Finally,we applied co-staining,immunohistochemical staining,RT-qPCR and western blotting to validate the protein and mRNA expression of both hub genes.We obtained 913 DEGs mainly related to inflammatory factors and immunity.GSEA results showed that differential genes were mainly enriched in IL-17 signaling pathway,lipid and atherosclerosis,rheumatoid arthritis,TNF signaling pathway,neutrophil extracellular trap formation,Staphylococcus aureus infection and other pathways.The intersection of the random forest algorithm and Cytoscape revealed both hub genes of CD300A and CXCL1.Experiments have shown that the both key genes of CD300A and CXCL1 shown increased expression in glomerular podocytes,and are related to the inflammation of diabetic nephropathy.And immunohistochemical staining and RT-qPCR further confirmed that the protein and mRNA expression level of CD300A or CXCL1 in glomeruli tissue in DN mice were increased.The expression levels of CD300A and CXCL1 increased significantly under HG(high glucose)stimulation,further confirming that diabetes can lead to increased levels of CD300A and CXCL1 at the cellular level.Through bioinformatics analysis,machine learning algorithms,and experimental research,CD300A and CXCL1 are confirmed as both potential biomarkers in diabetic nephropathy.And we further revealed the main pathways of differential genes and the differentially distributed immune infiltrating cells in diabetic nephropathy.
基金The study was supported by grants from the National Natural Science Foundation of China(51901160).
文摘There is currently no effective solution to the problem of poor prognosis and recurrence of HCC.The technology of immunotherapy and prognosis of genetic material has made continuous progress in recent years.In the study,a 5-gene signature was established for the prognosis of HCC through biological information,and the immune infiltration of HCC patients was studied.After studied HCC patients’immune infiltration,the paper screened the differential target genes of miR-126-3p in HCC downloaded from TCGA database,and uses WGCNA method to select the modular genes highly relevant to M2 macrophage.Then we use LASSO and COX regression analysis technology to establish the 5-gene signature.The nomogram is established by combining the prognostic score and clinical phenotype.Cibersort was empolyed to observe the immune infiltration in HCC patients.We revealed the biological pathways of HCC-related genes through GSEA and Metascape.The bioinformatics analysis of 2495 differential target genes finally constructed a 5-gene signature with a reliable prognostic ability(CDCA8,SLC41A3,PPM1G,TCOF1,GRPEL2).The combination of prognostic score and AJCC_Stage resulted in a more reliable prognosis ability.At the same time,10 immune cells that are differentially expressed in HCC patients were also found.8 GSEA pathways related to the prognosis were found.In the study,a reliable 5-gene signature was established based on the differential target gene of miR-126-3p to study the immune infiltration in HCC patients.It provides help for HCC-related prognosis research and immunotherapy.
文摘The quality of parts manufactured by laser powder bed fusion is closely related to the uniformity and density of the powder bed.In this work,the discrete element method is used to simulate the powder spreading process by different spreader geometries with rough substrate surfaces.The results indicate that reducing the spreader inclination angle significantly increases the number of force chains,enhances compaction,and consequently improves the quality of the powder bed.Studies also show that optimizing the bottom structure of the spreader can effectively reduce exposed areas.An arc-shaped structure promotes particle packing and filling,improving the powder distribution characteristics.A narrow spreader significantly affects the packing density of the powder bed at low layer gaps,whereas a wide spreader is relatively less constrained.At high spreading speeds,the spreader with an inclination angle of 135°produces the highest quality of the powder bed.R1000 performs excellently at larger layer gaps.The above findings provide valuable guidance for optimizing powder spreading strategies in the laser powder bed fusion process.
