In integrated circuits, the defects associated with photolithography are assumed to be in the shape of circular discs in order to perform the estimation of yield and fault analysis. However,real defects exhibit a grea...In integrated circuits, the defects associated with photolithography are assumed to be in the shape of circular discs in order to perform the estimation of yield and fault analysis. However,real defects exhibit a great variety of shapes. In this paper,a novel yield model is presented and the critical area model of short circuit is correspondingly provided. In comparison with the circular model corrently available, the new model takes the similarity shape to an original defect, the two-dimensional distributional characteristic of defects, the feature of a layout routing and the character of yield estimation into account. As for the aspect of prediction of yield, the experimental results show that the new model may predict the yield caused by real defects more accurately than the circular model does. It is significant that the yield is accurately estimated and improved using the proposed model.展开更多
Bone wound healing is a highly dynamic and precisely controlled process through which damaged bone undergoes repair and complete regeneration. External factors can alter this process, leading to delayed or failed bone...Bone wound healing is a highly dynamic and precisely controlled process through which damaged bone undergoes repair and complete regeneration. External factors can alter this process, leading to delayed or failed bone wound healing. The findings of recent studies suggest that the use of selective serotonin reuptake inhibitors(SSRIs) can reduce bone mass, precipitate osteoporotic fractures and increase the rate of dental implant failure. With 10% of Americans prescribed antidepressants, the potential of SSRIs to impair bone healing may adversely affect millions of patients’ ability to heal after sustaining trauma. Here, we investigate the effect of the SSRI sertraline on bone healing through pre-treatment with(10 mg·kg-1sertraline in drinking water, n = 26) or without(control, n = 30) SSRI followed by the creation of a 5-mm calvarial defect. Animals were randomized into three surgical groups:(a) empty/sham,(b) implanted with a DermaMatrix scaffold soak-loaded with sterile PBS or(c) DermaMatrix soak-loaded with542.5 ng BMP2. SSRI exposure continued until sacrifice in the exposed groups at 4 weeks after surgery. Sertraline exposure resulted in decreased bone healing with significant decreases in trabecular thickness, trabecular number and osteoclast dysfunction while significantly increasing mature collagen fiber formation. These findings indicate that sertraline exposure can impair bone wound healing through disruption of bone repair and regeneration while promoting or defaulting to scar formation within the defect site.展开更多
The oscillating voltage test is a nondestructive detection method for partial discharge of XLPE （cross linked polyethylene） cable and has been applied recently. This paper made three kinds of varying severity artifi...The oscillating voltage test is a nondestructive detection method for partial discharge of XLPE （cross linked polyethylene） cable and has been applied recently. This paper made three kinds of varying severity artificial defect models of cable joints in 10 kV XLPE cable. Oscillating voltage is applied to the model, by use of pulse current method to detect partial discharge signals. In order to study the statistical characteristics of partial discharge of cable joint under the oscillating voltage, three-dimensional statistical map has been made. The results show that for the same kind of defects, with the increases of the defect severity, the discharge interval extended, the magnitude and the number of partial discharge increase, for different kinds of defects, obvious differences exist among the maps, this may established a foundation for the further study of the partial discharge pattern recognition of XLPE cable under oscillating voltage.展开更多
A one dimensional model is developed for defective gap mode（DGM）with two types of boundary conditions：conducting mesh and conducting sleeve.For a periodically modulated system without defect,the normalized width of...A one dimensional model is developed for defective gap mode（DGM）with two types of boundary conditions：conducting mesh and conducting sleeve.For a periodically modulated system without defect,the normalized width of spectral gaps equals to the modulation factor,which is consistent with previous studies.For a periodic system with local defects introduced by the boundary conditions,it shows that the conducting-mesh-induced DGM is always well confined by spectral gaps while the conducting-sleeve-induced DGM is not.The defect location can be a useful tool to dynamically control the frequency and spatial periodicity of DGM inside spectral gaps.This controllability can be potentially applied to the interaction between gap eigenmodes and energetic particles in fusion plasmas,and optical microcavities and waveguides in photonic crystals.展开更多
inductive fault analysis is a technique for enumerating likely bridges that is limited by the weighted critical area computation. Based on the rectangle model of a real defect and mathematical morphology, an efficient...inductive fault analysis is a technique for enumerating likely bridges that is limited by the weighted critical area computation. Based on the rectangle model of a real defect and mathematical morphology, an efficient algorithm is presented to compute the weighted critical area of a layout. The algorithm avoids the need to determine which rectangles belong to a net and the merging of the critical area corresponding to a net pair. Experimental resuits showing the algorithm＇s performance are presented.展开更多
The fishtail in head and tail of the slabs was studied during V-H hot rolling process. With the application of ANSYS/LS-DYNA, simulation analysis was used to research this process. The various factors which have a gre...The fishtail in head and tail of the slabs was studied during V-H hot rolling process. With the application of ANSYS/LS-DYNA, simulation analysis was used to research this process. The various factors which have a great influence on fishtail shapes were analysed, such as initial width, initial thickness, radius of the edger roll and horizontal roll, edging draught,horizontal reduction rate, and friction coefficient of the surface. Then the curves that can describe the shapes were obtained. After a certain time of self-learning, the optimized curves were given out. At last, through the fitting of the simulation test results, the math models for the area of fishtail defect changing with the presented factors were received. The experimental results show that the accuracy of the prediction for the fishtail shapes is more than 95%. With the application of the prediction for the fishtail shapes and the area of the fishtail defect, the loss rate of the slab is decreased by about 0.1%.展开更多
Because atoms in high-entropy alloys （HEAs） coordinate in very different and distorted local environ- ments in the lattice sites, even for the same type of constituent, their point defects could highly vary. Therefo...Because atoms in high-entropy alloys （HEAs） coordinate in very different and distorted local environ- ments in the lattice sites, even for the same type of constituent, their point defects could highly vary. Therefore, theoretical determination of the thermodynamic quantities （i.e., defect formation enthalpies） of various point defects is rather challenging because each corresponding thermodynamic quantity of all involve constituents is not unique. The knowledge of these thermodynamic quantities is prerequisite for designing novel HEAs and understanding the mechanical and physical behaviors of HEAs. However, to date there has not been a good method to theoretically derive the defect formation enthalpies of HEAs. Here, using first-principles calculations within the density functional theory （DFT） in combina- tion of special quasi-random structure models （SQSs）, we have developed a general method to derive corresponding formation enthalpies of point defects in HEAs, using vacancy formation enthalpies of a four-component equiatomic fcc-type FeCoCrNi HEA as prototypical and benchmark examples. In difference from traditional ordered alloys, the vacancy formation enthalpies of FeCoCrNi HEA vary in a highly wide range from 0.72 to 2.89 eV for Fe, 0.88-2.90 eV for Co, 0.78-3.09 eV for Cr, and 0.91-2.95 eV for Ni due to high-level site-to-site lattice distortions and compositional complexities. On average, the vacancy formation enthalpies of 1.58 eV for Fe, 1.61 eV for Cr, 1.70 eV for Co and 1.89 eV for Ni are all larger than that （1.41 eV） of pure fcc nickel. This fact implies that the vacancies are much more difficult to be created than in nickel, indicating a reasonable agreement with the recent experimental observation that FeCoCrNi exhibits two orders of amplitudes enhancement of radiation tolerance with the suppression of void formation at elevated temperatures than in pure nickel.展开更多
Shrinkage porosity is a type of random distribution defects and exists in most large castings. Different from the periodic symmetry defects or certain distribution defects, shrinkage porosity presents a random "c...Shrinkage porosity is a type of random distribution defects and exists in most large castings. Different from the periodic symmetry defects or certain distribution defects, shrinkage porosity presents a random "cloud-like" configuration, which brings difficulties in quantifying the effective performance of defected casting. In this paper, the influences of random shrinkage porosity on the equivalent elastic modulus of QT400-18 casting were studied by a numerical statistics approach. An improved random algorithm was applied into the lattice model to simulate the "cloud-like" morphology of shrinkage porosity. Then, a large number of numerical samples containing random levels of shrinkage were generated by the proposed algorithm. The stress concentration factor and equivalent elastic modulus of these numerical samples were calculated. Based on a statistical approach, the effects of shrinkage porosity's distribution characteristics, such as area fraction, shape, and relative location on the casting's equivalent mechanical properties were discussed respectively. It is shown that the approach with randomly distributed defects has better predictive capabilities than traditional methods. The following conclusions can be drawn from the statistical simulations:(1) the effective modulus decreases remarkably if the shrinkage porosity percent is greater than 1.5%;(2) the average Stress Concentration Factor(SCF) produced by shrinkage porosity is about 2.0;(3) the defect's length across the loading direction plays a more important role in the effective modulus than the length along the loading direction;(4) the surface defect perpendicular to loading direction reduces the mean modulus about 1.5% more than a defect of other position.展开更多
The electrical properties of TiO2-based varistor ceramics with different amount of CeO2 were investigated by measuring the properties of V-I, permittivity, density and boundary defect barriers. It is found that an opt...The electrical properties of TiO2-based varistor ceramics with different amount of CeO2 were investigated by measuring the properties of V-I, permittivity, density and boundary defect barriers. It is found that an optimal composition doped with 0.7% CeO2 exhibits the highest nonlinear coefficient of 10.5, the highest breakdown voltage of 12.77 V·mm^-1, the ultrahigh permittivity of 82900（measured at 1 kHz）, and the highest density of 4.15 g·cm^-3, which is consistent with the highest and narrowest grain-boundary defect barriers. In order to illustrate the grain boundary barriers formation in TiO2-Nb2O5-MnCO3-CeO2 varistor, an grain-boundary defect barrier model was also introduced.展开更多
Exploring the passivity and electrochemical behavior of Inconel alloy 625 in nitric acid solution could open up possibilities for potential applications,either in bulk form or as claddings.Hence,this research investig...Exploring the passivity and electrochemical behavior of Inconel alloy 625 in nitric acid solution could open up possibilities for potential applications,either in bulk form or as claddings.Hence,this research investigates corrosion behavior and passivity of Inconel alloy 625 in nitric acid solutions of varying concentrations(0.01–1.00 mol/L)using a range of analytical techniques,including potentiodynamic polarization testing,chronoamperometry measurement,Mott-Schottky(MS)analysis,X-ray diffraction(XRD)approaches,and point defect modeling(PDM).Results demonstrate that corrosion current density does not necessarily decrease with increasing electrolyte concentration(Please check it out).Additionally,the alloy exhibits higher passive film transpassive potentials in more concentrated solutions.Potentiostatic polarization tests reveal an increase in steady-state current densities attributed to the passive films formed in more concentrated solutions.Lower electrolyte concentrations lead to the formation of more intact bilayered passive films.In this context,the formation of passive films is elucidated by examining the generation and annihilation of point defects.The semiconducting behavior of passive layers is further examined through XRD patterns and electrochemical properties.According to PDM,the diffusivity of point defects within the passive films and their respective donor densities can be closely correlated.展开更多
Defect detection assurance on production lines machine-vision-based surface is important in quality This paper presents a fast defect detection method using the weighted least-squares model. We assume that an inspecti...Defect detection assurance on production lines machine-vision-based surface is important in quality This paper presents a fast defect detection method using the weighted least-squares model. We assume that an inspection image can be regarded as a combination of a defect-free template image and a residual image. The defect-free template image is generated from training samples adaptively, and the residual image is the result of the subtraction between each inspection image and corresponding defect-free template image. In the weighted least-squares model, the residual error near the edge is suppressed to reduce the false alarms caused by spatial misalignment. Experiment results on different types of buttons show that the proposed method is robust to illumination vibration and rotation deviation and produces results that are better than those of two other methods.展开更多
Physical defects have always played an important role in integrated circuit(IC)yields,and the design sensitivity to these physical elements has continued to increase in today’s nanometer technologies.The modeling of ...Physical defects have always played an important role in integrated circuit(IC)yields,and the design sensitivity to these physical elements has continued to increase in today’s nanometer technologies.The modeling of defect out-lines that exhibit a great variety of defect shapes is usually modeled as a circle,which causes the errors of critical area estimation.Since the outlines of 70%defects approximate to elliptical shapes,a novel yield model associated with elliptical outlines of defects is presented.This model is more general than the circular defects model as the latter is only an instance of the proposed model.Comparisons of the new and circular models in the experiment show that the new model can predict yield caused by real defects more accurately than what the circular model does,which is of significance for the prediction and improvement of the yield.展开更多
Metallic glasses(MGs),a metastable material far from equilibrium,exhibit intricate dynamic relaxation behaviors.The challenge lies in developing a model that accurately describes the dynamics and deforma-tion mechanis...Metallic glasses(MGs),a metastable material far from equilibrium,exhibit intricate dynamic relaxation behaviors.The challenge lies in developing a model that accurately describes the dynamics and deforma-tion mechanisms of MG.This paper introduces a model integrating dynamic relaxation with deformation behavior.Validation through dynamic mechanical analysis,stress relaxation,creep,and strain recovery tests confirm the existence of four deformation modes:elasticity,anelasticity fromβrelaxation,anelas-ticity fromαrelaxation at low temperatures,and viscoplasticity fromαrelaxation at high temperatures.The model captures all of these deformation modes.The dynamical mechanical spectrum and stress re-laxation spectrum unveil dynamic features during glass to liquid transition,and a simple and effective experimental method was developed for identifying ultra-low-frequency dynamic relaxation.This work provides new perspectives on the study of relaxation dynamics in glassy states and establishes impor-tant connections between dynamic relaxation behavior and deformation mechanisms.These findings lay a theoretical and experimental foundation for the broad application of MGs.展开更多
Exosomes derived from human adipose-derived stem cells (hADSCs-Exos) have shown potential as an effectivetherapeutic tool for repairing bone defects. Although metal-organic framework (MOF) scaffolds are promisingstrat...Exosomes derived from human adipose-derived stem cells (hADSCs-Exos) have shown potential as an effectivetherapeutic tool for repairing bone defects. Although metal-organic framework (MOF) scaffolds are promisingstrategies for bone tissue regeneration, their potential use for exosome loading remains unexplored. In this study,motivated by the potential advantages of hADSCs-Exos and Mg-GA MOF, we designed and synthesized anexosome-functionalized cell-free PLGA/Mg-GA MOF (PLGA/Exo-Mg-GA MOF) scaffold, taking using of thebenefits of hADSCs-Exos, Mg2+, and gallic acid (GA) to construct unique nanostructural interfaces to enhanceosteogenic, angiogenic and anti-inflammatory capabilities simultaneously. Our in vitro work demonstrated thebeneficial effects of PLGA/Exo-Mg-GA MOF composite scaffolds on the osteogenic effects in human bonemarrow-derived mesenchymal stem cells (hBMSCs) and angiogenic effects in human umbilical endothelial cells(HUVECs). Slowly released hADSCs-Exos from composite scaffolds were phagocytosed by co-cultured cells,stabilized the bone graft environment, ensured blood supply, promoted osteogenic differentiation, and acceleratedbone reconstruction. Furthermore, our in vivo experiments with rat calvarial defect model showed thatPLGA/Exo-Mg-GA MOF scaffolds promoted new bone formation and satisfactory osseointegration. Overall, weprovide valuable new insights for designing exosome-coated nanocomposite scaffolds with enhanced osteogenesisproperty.展开更多
Intersection-related crashes are associated with high proportion of accidents involving drivers, occupants, pedestrians, and cyclists. In general, the purpose of intersection safety analysis is to determine the impact...Intersection-related crashes are associated with high proportion of accidents involving drivers, occupants, pedestrians, and cyclists. In general, the purpose of intersection safety analysis is to determine the impact of safety-related variables on pedestrians, cyclists and vehicles, so as to facilitate the design of effective and efficient countermeasure strategies to improve safety at intersections. This study investigates the effects of traffic, environ- mental, intersection geometric and pavement-related characteristics on total crash fre- quencies at intersections. A random-parameter Poisson model was used with crash data from 357 signalized intersections in Chicago from 2004 to 2010. The results indicate that out of the identified factors, evening peak period traffic volume, pavement condition, and unlighted intersections have the greatest effects on crash frequencies. Overall, the results seek to suggest that, in order to improve effective highway-related safety countermeasures at intersections, significant attention must be focused on ensuring that pavements are adequately maintained and intersections should be well lighted. It needs to be mentioned that, projects could be implemented at and around the study intersections during the study period （7 years）, which could affect the crash frequency over the time. This is an important variable which could be a part of the future studies to investigate the impacts of safety related works at intersections and their marginal effects on crash frequency at signalized intersections.展开更多
Using a previous model, which was developed to describe the light-induced creation ofthe defect density in the a-Si：H gap states, we present in this work a computer simulation of the a-Si：H p-i-n solar cell behavior...Using a previous model, which was developed to describe the light-induced creation ofthe defect density in the a-Si：H gap states, we present in this work a computer simulation of the a-Si：H p-i-n solar cell behavior under continuous illumination. We have considered the simple case of a monochromatic light beam nonuniformly absorbed. As a consequence of this light-absorption profile, the increase of the dangling bond density is assumed to be inhomogeneous over the intrinsic layer （i-layer）. We investigate the internal variable profiles during illumination to understand in more detail the changes resulting from the light-induced degradation effect. Changes in the cell external parameters including the open circuit voltage, Voc, the short circuit current density, Jsc, the fill factor, FF, and the maximum power density, Pmax, are also presented. This shows, in addition, the free carrier mobility influence. The obtained results show that Voc seems to be the less affected parameter by the light-induced increase of the dangling bond density. Moreover, its degradation is very weak-sensitive to the free carrier mobility. Finally, the free hole mobility effect is found to be more important than that of electrons in the improvement of the solar cell performance.展开更多
Next-generation synthetic bone graft therapies will most likely be composed of resorbable polymers in combination with bioactive components.In this article,we continue our exploration of E1001(1k),a tyrosine-derived p...Next-generation synthetic bone graft therapies will most likely be composed of resorbable polymers in combination with bioactive components.In this article,we continue our exploration of E1001(1k),a tyrosine-derived polycarbonate,as an orthopedic implant material.Specifically,we use E1001(1k),which is degradable,nontoxic,and osteoconductive,to fabricate porous bone regeneration scaffolds that were enhanced by two different types of calcium phosphate(CP)coatings:in one case,pure dicalcium phosphate dihydrate was precipitated on the scaffold surface and throughout its porous structure(E1001(1k)+CP).In the other case,bone matrix minerals(BMM)such as zinc,manganese and fluoride were co-precipitated within the dicalcium phosphate dihydrate coating(E1001(1k)+BMM).These scaffold compositions were compared against each other and against ChronOS(Synthes USA,West Chester,PA,USA),a clinically used bone graft substitute(BGS),which served as the positive control in our experimental design.This BGS is composed of poly(lactide co-e-caprolactone)and beta-tricalcium phosphate.We used the established rabbit calvaria critical-sized defect model to determine bone regeneration within the defect for each of the three scaffold compositions.New bone formation was determined after 2,4,6,8 and 12 weeks by micro-computerized tomography(mCT)and histology.The experimental tyrosine-derived polycarbonate,enhanced with dicalcium phosphate dihydrate,E1001(1k)+CP,supported significant bone formation within the defects and was superior to the same scaffold containing a mix of BMM,E1001(1k)+BMM.The comparison with the commercially available BGS was complicated by the large variability in bone formation observed for the laboratory preparations of E1001(1k)scaffolds.At all time points,there was a trend for E1001(1k)+CP to be superior to the commercial BGS.However,only at the 6-week time point did this trend reach statistical significance.Detailed analysis of the μCT data suggested an increase in bone formation from 2 through 12 weeks in implant sites treated with E1001(1k)+CP.At 2 and 4 weeks post-implantation,bone formation occurred at the interface where the E1001(1k)+CP scaffold was in contact with the bone borders of the implant site.Thereafter,during weeks 6,8 and 12 bone formation progressed throughout the E1001(1k)+CP test implants.This trend was not observed with E1001(1k)+BMM scaffolds or the clinically used BGS.Our results suggest that E1001(1k)+CP should be tested further for osteoregenerative applications.展开更多
文摘In integrated circuits, the defects associated with photolithography are assumed to be in the shape of circular discs in order to perform the estimation of yield and fault analysis. However,real defects exhibit a great variety of shapes. In this paper,a novel yield model is presented and the critical area model of short circuit is correspondingly provided. In comparison with the circular model corrently available, the new model takes the similarity shape to an original defect, the two-dimensional distributional characteristic of defects, the feature of a layout routing and the character of yield estimation into account. As for the aspect of prediction of yield, the experimental results show that the new model may predict the yield caused by real defects more accurately than the circular model does. It is significant that the yield is accurately estimated and improved using the proposed model.
基金supported by a grant from the Musculoskeletal Transplant Foundation (JC)the National Institute of Health, the National Institute of Aging [NIH-NIA PO1-AG036675] (ME, WDH)+4 种基金in part by the Department of Veterans Affairs (VA Merit Award BX000333, ACL 1I01CX000930-01, WDH)funded through a training grant from the National Institutes of Health National Institute of Dental and Craniofacial Research [5T32DE017551]S.H. is funded through a fellowship from the National Institutes of Health National Institute of Dental and Craniofacial Research [5F32DE02471202]supported by the National Institutes of Health National Institute of General Medicine [P30GM103331]
文摘Bone wound healing is a highly dynamic and precisely controlled process through which damaged bone undergoes repair and complete regeneration. External factors can alter this process, leading to delayed or failed bone wound healing. The findings of recent studies suggest that the use of selective serotonin reuptake inhibitors(SSRIs) can reduce bone mass, precipitate osteoporotic fractures and increase the rate of dental implant failure. With 10% of Americans prescribed antidepressants, the potential of SSRIs to impair bone healing may adversely affect millions of patients’ ability to heal after sustaining trauma. Here, we investigate the effect of the SSRI sertraline on bone healing through pre-treatment with(10 mg·kg-1sertraline in drinking water, n = 26) or without(control, n = 30) SSRI followed by the creation of a 5-mm calvarial defect. Animals were randomized into three surgical groups:(a) empty/sham,(b) implanted with a DermaMatrix scaffold soak-loaded with sterile PBS or(c) DermaMatrix soak-loaded with542.5 ng BMP2. SSRI exposure continued until sacrifice in the exposed groups at 4 weeks after surgery. Sertraline exposure resulted in decreased bone healing with significant decreases in trabecular thickness, trabecular number and osteoclast dysfunction while significantly increasing mature collagen fiber formation. These findings indicate that sertraline exposure can impair bone wound healing through disruption of bone repair and regeneration while promoting or defaulting to scar formation within the defect site.
文摘The oscillating voltage test is a nondestructive detection method for partial discharge of XLPE （cross linked polyethylene） cable and has been applied recently. This paper made three kinds of varying severity artificial defect models of cable joints in 10 kV XLPE cable. Oscillating voltage is applied to the model, by use of pulse current method to detect partial discharge signals. In order to study the statistical characteristics of partial discharge of cable joint under the oscillating voltage, three-dimensional statistical map has been made. The results show that for the same kind of defects, with the increases of the defect severity, the discharge interval extended, the magnitude and the number of partial discharge increase, for different kinds of defects, obvious differences exist among the maps, this may established a foundation for the further study of the partial discharge pattern recognition of XLPE cable under oscillating voltage.
基金supported by National Natural Science Foundation of China(No.11405271)
文摘A one dimensional model is developed for defective gap mode（DGM）with two types of boundary conditions：conducting mesh and conducting sleeve.For a periodically modulated system without defect,the normalized width of spectral gaps equals to the modulation factor,which is consistent with previous studies.For a periodic system with local defects introduced by the boundary conditions,it shows that the conducting-mesh-induced DGM is always well confined by spectral gaps while the conducting-sleeve-induced DGM is not.The defect location can be a useful tool to dynamically control the frequency and spatial periodicity of DGM inside spectral gaps.This controllability can be potentially applied to the interaction between gap eigenmodes and energetic particles in fusion plasmas,and optical microcavities and waveguides in photonic crystals.
文摘inductive fault analysis is a technique for enumerating likely bridges that is limited by the weighted critical area computation. Based on the rectangle model of a real defect and mathematical morphology, an efficient algorithm is presented to compute the weighted critical area of a layout. The algorithm avoids the need to determine which rectangles belong to a net and the merging of the critical area corresponding to a net pair. Experimental resuits showing the algorithm＇s performance are presented.
基金Project(N100307002)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(61174115)supported by the National Natural Science Foundation of China
文摘The fishtail in head and tail of the slabs was studied during V-H hot rolling process. With the application of ANSYS/LS-DYNA, simulation analysis was used to research this process. The various factors which have a great influence on fishtail shapes were analysed, such as initial width, initial thickness, radius of the edger roll and horizontal roll, edging draught,horizontal reduction rate, and friction coefficient of the surface. Then the curves that can describe the shapes were obtained. After a certain time of self-learning, the optimized curves were given out. At last, through the fitting of the simulation test results, the math models for the area of fishtail defect changing with the presented factors were received. The experimental results show that the accuracy of the prediction for the fishtail shapes is more than 95%. With the application of the prediction for the fishtail shapes and the area of the fishtail defect, the loss rate of the slab is decreased by about 0.1%.
基金supported by the National Science Fund for Distinguished Young Scholars (No. 51725103)by the National Natural Science Foundation of China (Grant Nos. 51671193 and 51474202)+7 种基金by the Science Challenging (Project No. TZ2016004)by the “Hundred Talented Project” of the Chinese Academy of Sciencesfinancially supported by the National Natural Science Foundation of China (Nos. 51671018 and 51671021)111 Project (No. B07003)International S&T Cooperation Program of China (No. 2015DFG52600)the Program for Changjiang Scholars and Innovative Research Team in University of China (No. IRT 14R05)the Projects of SKL-AMM-USTB (Nos. 2016Z-04, 2016-09 and 2016Z-16)supported by the Hong Kong URC grant under the contract with City University of Hong Kong
文摘Because atoms in high-entropy alloys （HEAs） coordinate in very different and distorted local environ- ments in the lattice sites, even for the same type of constituent, their point defects could highly vary. Therefore, theoretical determination of the thermodynamic quantities （i.e., defect formation enthalpies） of various point defects is rather challenging because each corresponding thermodynamic quantity of all involve constituents is not unique. The knowledge of these thermodynamic quantities is prerequisite for designing novel HEAs and understanding the mechanical and physical behaviors of HEAs. However, to date there has not been a good method to theoretically derive the defect formation enthalpies of HEAs. Here, using first-principles calculations within the density functional theory （DFT） in combina- tion of special quasi-random structure models （SQSs）, we have developed a general method to derive corresponding formation enthalpies of point defects in HEAs, using vacancy formation enthalpies of a four-component equiatomic fcc-type FeCoCrNi HEA as prototypical and benchmark examples. In difference from traditional ordered alloys, the vacancy formation enthalpies of FeCoCrNi HEA vary in a highly wide range from 0.72 to 2.89 eV for Fe, 0.88-2.90 eV for Co, 0.78-3.09 eV for Cr, and 0.91-2.95 eV for Ni due to high-level site-to-site lattice distortions and compositional complexities. On average, the vacancy formation enthalpies of 1.58 eV for Fe, 1.61 eV for Cr, 1.70 eV for Co and 1.89 eV for Ni are all larger than that （1.41 eV） of pure fcc nickel. This fact implies that the vacancies are much more difficult to be created than in nickel, indicating a reasonable agreement with the recent experimental observation that FeCoCrNi exhibits two orders of amplitudes enhancement of radiation tolerance with the suppression of void formation at elevated temperatures than in pure nickel.
基金supported by the National Natural Science Foundation of China(Grant No.51305350)the Basic Research Foundation of NWPU(No.3102014JCQ01045)
文摘Shrinkage porosity is a type of random distribution defects and exists in most large castings. Different from the periodic symmetry defects or certain distribution defects, shrinkage porosity presents a random "cloud-like" configuration, which brings difficulties in quantifying the effective performance of defected casting. In this paper, the influences of random shrinkage porosity on the equivalent elastic modulus of QT400-18 casting were studied by a numerical statistics approach. An improved random algorithm was applied into the lattice model to simulate the "cloud-like" morphology of shrinkage porosity. Then, a large number of numerical samples containing random levels of shrinkage were generated by the proposed algorithm. The stress concentration factor and equivalent elastic modulus of these numerical samples were calculated. Based on a statistical approach, the effects of shrinkage porosity's distribution characteristics, such as area fraction, shape, and relative location on the casting's equivalent mechanical properties were discussed respectively. It is shown that the approach with randomly distributed defects has better predictive capabilities than traditional methods. The following conclusions can be drawn from the statistical simulations:(1) the effective modulus decreases remarkably if the shrinkage porosity percent is greater than 1.5%;(2) the average Stress Concentration Factor(SCF) produced by shrinkage porosity is about 2.0;(3) the defect's length across the loading direction plays a more important role in the effective modulus than the length along the loading direction;(4) the surface defect perpendicular to loading direction reduces the mean modulus about 1.5% more than a defect of other position.
文摘The electrical properties of TiO2-based varistor ceramics with different amount of CeO2 were investigated by measuring the properties of V-I, permittivity, density and boundary defect barriers. It is found that an optimal composition doped with 0.7% CeO2 exhibits the highest nonlinear coefficient of 10.5, the highest breakdown voltage of 12.77 V·mm^-1, the ultrahigh permittivity of 82900（measured at 1 kHz）, and the highest density of 4.15 g·cm^-3, which is consistent with the highest and narrowest grain-boundary defect barriers. In order to illustrate the grain boundary barriers formation in TiO2-Nb2O5-MnCO3-CeO2 varistor, an grain-boundary defect barrier model was also introduced.
基金the generous support provided by the Natural Sciences and Engineering Research Council of Canada(NSERC)(RGPIN-2017–04368)the Canada Research Chair Program(CRC-2019–00017),Ocean Frontier Institute,and Dalhousie University in making this work possible
文摘Exploring the passivity and electrochemical behavior of Inconel alloy 625 in nitric acid solution could open up possibilities for potential applications,either in bulk form or as claddings.Hence,this research investigates corrosion behavior and passivity of Inconel alloy 625 in nitric acid solutions of varying concentrations(0.01–1.00 mol/L)using a range of analytical techniques,including potentiodynamic polarization testing,chronoamperometry measurement,Mott-Schottky(MS)analysis,X-ray diffraction(XRD)approaches,and point defect modeling(PDM).Results demonstrate that corrosion current density does not necessarily decrease with increasing electrolyte concentration(Please check it out).Additionally,the alloy exhibits higher passive film transpassive potentials in more concentrated solutions.Potentiostatic polarization tests reveal an increase in steady-state current densities attributed to the passive films formed in more concentrated solutions.Lower electrolyte concentrations lead to the formation of more intact bilayered passive films.In this context,the formation of passive films is elucidated by examining the generation and annihilation of point defects.The semiconducting behavior of passive layers is further examined through XRD patterns and electrochemical properties.According to PDM,the diffusivity of point defects within the passive films and their respective donor densities can be closely correlated.
文摘Defect detection assurance on production lines machine-vision-based surface is important in quality This paper presents a fast defect detection method using the weighted least-squares model. We assume that an inspection image can be regarded as a combination of a defect-free template image and a residual image. The defect-free template image is generated from training samples adaptively, and the residual image is the result of the subtraction between each inspection image and corresponding defect-free template image. In the weighted least-squares model, the residual error near the edge is suppressed to reduce the false alarms caused by spatial misalignment. Experiment results on different types of buttons show that the proposed method is robust to illumination vibration and rotation deviation and produces results that are better than those of two other methods.
基金supported by the Hi-Tech Research and Development Program of China(No.2003AA1Z2163).
文摘Physical defects have always played an important role in integrated circuit(IC)yields,and the design sensitivity to these physical elements has continued to increase in today’s nanometer technologies.The modeling of defect out-lines that exhibit a great variety of defect shapes is usually modeled as a circle,which causes the errors of critical area estimation.Since the outlines of 70%defects approximate to elliptical shapes,a novel yield model associated with elliptical outlines of defects is presented.This model is more general than the circular defects model as the latter is only an instance of the proposed model.Comparisons of the new and circular models in the experiment show that the new model can predict yield caused by real defects more accurately than what the circular model does,which is of significance for the prediction and improvement of the yield.
基金supported by the National Natu-ral Science Foundation of China(Nos.12472069 and 52271153)the Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province(No.2021JC-12)+5 种基金Guo-Jian Lyu is supported by the National Natural Science Foundation of China(No.52301219)the Fundamental Research Funds for the Cen-tral Universities(No.5000230147)Yun-Jiang Wang was finan-cially supported by the National Natural Science Foundation of China(No.12472112)Y.Yang acknowledges financial support from the Research Grant Council(RGC),the Hong Kong Government through the General Research Fund(GRF)(Nos.CityU11206362 and N_CityU109/21)E.Pineda acknowledges financial support from MCIN/AEI(Nos.PID2020-112975GB-I00/10.13039/501100011033 and CEX2023-001300-M/10.13039/501100011033)Generalitat de Catalunya(No.2021SGR00343).
文摘Metallic glasses(MGs),a metastable material far from equilibrium,exhibit intricate dynamic relaxation behaviors.The challenge lies in developing a model that accurately describes the dynamics and deforma-tion mechanisms of MG.This paper introduces a model integrating dynamic relaxation with deformation behavior.Validation through dynamic mechanical analysis,stress relaxation,creep,and strain recovery tests confirm the existence of four deformation modes:elasticity,anelasticity fromβrelaxation,anelas-ticity fromαrelaxation at low temperatures,and viscoplasticity fromαrelaxation at high temperatures.The model captures all of these deformation modes.The dynamical mechanical spectrum and stress re-laxation spectrum unveil dynamic features during glass to liquid transition,and a simple and effective experimental method was developed for identifying ultra-low-frequency dynamic relaxation.This work provides new perspectives on the study of relaxation dynamics in glassy states and establishes impor-tant connections between dynamic relaxation behavior and deformation mechanisms.These findings lay a theoretical and experimental foundation for the broad application of MGs.
基金Natural science Foundation of Liaoning Province,China,grant number of 2020-ZLLH-40.
文摘Exosomes derived from human adipose-derived stem cells (hADSCs-Exos) have shown potential as an effectivetherapeutic tool for repairing bone defects. Although metal-organic framework (MOF) scaffolds are promisingstrategies for bone tissue regeneration, their potential use for exosome loading remains unexplored. In this study,motivated by the potential advantages of hADSCs-Exos and Mg-GA MOF, we designed and synthesized anexosome-functionalized cell-free PLGA/Mg-GA MOF (PLGA/Exo-Mg-GA MOF) scaffold, taking using of thebenefits of hADSCs-Exos, Mg2+, and gallic acid (GA) to construct unique nanostructural interfaces to enhanceosteogenic, angiogenic and anti-inflammatory capabilities simultaneously. Our in vitro work demonstrated thebeneficial effects of PLGA/Exo-Mg-GA MOF composite scaffolds on the osteogenic effects in human bonemarrow-derived mesenchymal stem cells (hBMSCs) and angiogenic effects in human umbilical endothelial cells(HUVECs). Slowly released hADSCs-Exos from composite scaffolds were phagocytosed by co-cultured cells,stabilized the bone graft environment, ensured blood supply, promoted osteogenic differentiation, and acceleratedbone reconstruction. Furthermore, our in vivo experiments with rat calvarial defect model showed thatPLGA/Exo-Mg-GA MOF scaffolds promoted new bone formation and satisfactory osseointegration. Overall, weprovide valuable new insights for designing exosome-coated nanocomposite scaffolds with enhanced osteogenesisproperty.
文摘Intersection-related crashes are associated with high proportion of accidents involving drivers, occupants, pedestrians, and cyclists. In general, the purpose of intersection safety analysis is to determine the impact of safety-related variables on pedestrians, cyclists and vehicles, so as to facilitate the design of effective and efficient countermeasure strategies to improve safety at intersections. This study investigates the effects of traffic, environ- mental, intersection geometric and pavement-related characteristics on total crash fre- quencies at intersections. A random-parameter Poisson model was used with crash data from 357 signalized intersections in Chicago from 2004 to 2010. The results indicate that out of the identified factors, evening peak period traffic volume, pavement condition, and unlighted intersections have the greatest effects on crash frequencies. Overall, the results seek to suggest that, in order to improve effective highway-related safety countermeasures at intersections, significant attention must be focused on ensuring that pavements are adequately maintained and intersections should be well lighted. It needs to be mentioned that, projects could be implemented at and around the study intersections during the study period （7 years）, which could affect the crash frequency over the time. This is an important variable which could be a part of the future studies to investigate the impacts of safety related works at intersections and their marginal effects on crash frequency at signalized intersections.
文摘Using a previous model, which was developed to describe the light-induced creation ofthe defect density in the a-Si：H gap states, we present in this work a computer simulation of the a-Si：H p-i-n solar cell behavior under continuous illumination. We have considered the simple case of a monochromatic light beam nonuniformly absorbed. As a consequence of this light-absorption profile, the increase of the dangling bond density is assumed to be inhomogeneous over the intrinsic layer （i-layer）. We investigate the internal variable profiles during illumination to understand in more detail the changes resulting from the light-induced degradation effect. Changes in the cell external parameters including the open circuit voltage, Voc, the short circuit current density, Jsc, the fill factor, FF, and the maximum power density, Pmax, are also presented. This shows, in addition, the free carrier mobility influence. The obtained results show that Voc seems to be the less affected parameter by the light-induced increase of the dangling bond density. Moreover, its degradation is very weak-sensitive to the free carrier mobility. Finally, the free hole mobility effect is found to be more important than that of electrons in the improvement of the solar cell performance.
基金This research was sponsored by the Armed Forces Institute of Regenerative Medicine(AFIRM)award number W81XWH-08-2-0034The US Army Medical Research Acquisition Activity,820 Chandler Street,Fort Detrick MD 21702-5014 is the awarding and administering acquisition office。
文摘Next-generation synthetic bone graft therapies will most likely be composed of resorbable polymers in combination with bioactive components.In this article,we continue our exploration of E1001(1k),a tyrosine-derived polycarbonate,as an orthopedic implant material.Specifically,we use E1001(1k),which is degradable,nontoxic,and osteoconductive,to fabricate porous bone regeneration scaffolds that were enhanced by two different types of calcium phosphate(CP)coatings:in one case,pure dicalcium phosphate dihydrate was precipitated on the scaffold surface and throughout its porous structure(E1001(1k)+CP).In the other case,bone matrix minerals(BMM)such as zinc,manganese and fluoride were co-precipitated within the dicalcium phosphate dihydrate coating(E1001(1k)+BMM).These scaffold compositions were compared against each other and against ChronOS(Synthes USA,West Chester,PA,USA),a clinically used bone graft substitute(BGS),which served as the positive control in our experimental design.This BGS is composed of poly(lactide co-e-caprolactone)and beta-tricalcium phosphate.We used the established rabbit calvaria critical-sized defect model to determine bone regeneration within the defect for each of the three scaffold compositions.New bone formation was determined after 2,4,6,8 and 12 weeks by micro-computerized tomography(mCT)and histology.The experimental tyrosine-derived polycarbonate,enhanced with dicalcium phosphate dihydrate,E1001(1k)+CP,supported significant bone formation within the defects and was superior to the same scaffold containing a mix of BMM,E1001(1k)+BMM.The comparison with the commercially available BGS was complicated by the large variability in bone formation observed for the laboratory preparations of E1001(1k)scaffolds.At all time points,there was a trend for E1001(1k)+CP to be superior to the commercial BGS.However,only at the 6-week time point did this trend reach statistical significance.Detailed analysis of the μCT data suggested an increase in bone formation from 2 through 12 weeks in implant sites treated with E1001(1k)+CP.At 2 and 4 weeks post-implantation,bone formation occurred at the interface where the E1001(1k)+CP scaffold was in contact with the bone borders of the implant site.Thereafter,during weeks 6,8 and 12 bone formation progressed throughout the E1001(1k)+CP test implants.This trend was not observed with E1001(1k)+BMM scaffolds or the clinically used BGS.Our results suggest that E1001(1k)+CP should be tested further for osteoregenerative applications.
