A feasible method to improve the reliability and processing efficiency of large vibrating screen via the application of an elastic screen surface with multiple attached substructures （ESSMAS） was proposed. In the ES...A feasible method to improve the reliability and processing efficiency of large vibrating screen via the application of an elastic screen surface with multiple attached substructures （ESSMAS） was proposed. In the ESSMAS, every screen rod, with ends embedded into elastomer, is coupled to the main screen structure in a relatively flexible manner. The theoretical analysis was conducted, which consists of establishing dynamic model promoted from the fuzzy structure theory as well as calculating for the equivalent stiffness of each attached structure. According to the numerical simulation using the NEWMARK-fl integration method, this assembling pattern significantly leads to the screen surface/rod having larger vibration intensity than that of the corresponding position on screen structure, which specifically, with an averaged acceleration amplitude increasing ratio of 11.37% in theoretical analysis and 20.27% in experimental test. The experimental results, within a tolerant error, also confirm the established model and demonstrate the feasibility of ESSMAS.展开更多
A crystal-plasticity cyclic constitutive model of polycrystalline material considering intra-granular heterogeneous dislocation substructures,in terms of three dislocation categories:mobile dislocations,immobile dislo...A crystal-plasticity cyclic constitutive model of polycrystalline material considering intra-granular heterogeneous dislocation substructures,in terms of three dislocation categories:mobile dislocations,immobile dislocations in the cell interiors and in the cell walls,is proposed based on the existing microscopic and macroscopic experimental results.The multiplication,annihilation,rearrangement and immobilization of dislocations on each slip system are taken as the basic evolutionary mechanism of the three dislocation categories,and the cross-slip of screw dislocations is viewed as the dynamic recovery mechanism at room temperature.The slip resistance associated with the isotropic hardening rule results from the interactions of dislocations on the slip systems.Meanwhile,a modified nonlinear kinematic hardening rule and a rate-dependent flow rule at the slip system level are employed to improve the predictive capability of the model for ratchetting deformation.The predictive ability of the developed model to uniaxial and mul-tiaxial ratchetting in macroscopic scale is verified by comparing with the experimental results of polycrystalline 316L stainless steel.The ratchetting in intra-granular scale which is obviously dependent on the crystallographic orientation and stress levels can be reasonably predicted by the proposed model.展开更多
BACKGROUND Radiation dose to specific cardiac substructures can have a significant on treatment related morbidity and mortality,yet definition of these structures is labor intensive and not standard.Autosegmentation s...BACKGROUND Radiation dose to specific cardiac substructures can have a significant on treatment related morbidity and mortality,yet definition of these structures is labor intensive and not standard.Autosegmentation software may potentially address these issues,however it is unclear whether this approach can be broadly applied across different treatment planning conditions.We investigated the feasibility of autosegmentation of the cardiac substructures in four-dimensional(4D)computed tomography(CT),respiratory-gated,non-contrasted imaging.AIM To determine whether autosegmentation can be successfully employed on 4DCT respiratory-gated,non-contrasted imaging.METHODS We included patients who underwent stereotactic body radiation therapy for inoperable,early-stage non-small cell lung cancer from 2007 to 2019.All patients were simulated via 4DCT imaging with respiratory gating without intravenous contrast.Generated structure quality was evaluated by degree of required manual edits and volume discrepancy between the autocontoured structures and its edited sister structure.RESULTS Initial 17-structure cardiac atlas was generated with 20 patients followed by three successive iterations of 10 patients using MIM software.The great vessels and heart chambers were reliably autosegmented with most edits considered minor.In contrast,coronary arteries either failed to be autosegmented or the generated structures required major alterations necessitating deletion and manual definition.Similarly,the generated mitral and tricuspid valves were poor whereas the aortic and pulmonary valves required at least minor and moderate changes respectively.For the majority of subsites,the additional samples did not appear to substantially impact the quality of generated structures.Volumetric analysis between autosegmented and its manually edited sister structure yielded comparable findings to the physician-based assessment of structure quality.CONCLUSION The use of MIM software with 30-sample subject library was found to be useful in delineating many of the heart substructures with acceptable clinical accuracy on respiratory-gated 4DCT imaging.Small volume structures,such as the coronary arteries were poorly autosegmented and require manual definition.展开更多
Combining the advantages of numerical simulation with experimental testing,real-time dynamic substructure(RTDS)testing provides a new experimental method for the investigation of engineered structures.However,not all ...Combining the advantages of numerical simulation with experimental testing,real-time dynamic substructure(RTDS)testing provides a new experimental method for the investigation of engineered structures.However,not all unmodeled parts can be physically tested,as testing is often limited by the capacity of the test facility.Model updating is a good option to improve the modeling accuracy for numerical substructures in RTDS.In this study,a model updating method is introduced,which has great performance in describing this nonlinearity.In order to determine the optimal parameters in this model,an Unscented Kalman Filter(UKF)-based algorithm was applied to extract the knowledge contained in the sensors data.All the parameters that need to be identified are listed as the extended state variables,and the identification was achieved via the step-by-step state prediction and state update process.Effectiveness of the proposed method was verified through a group of experimental data,and results showed good agreement.Furthermore,the proposed method was compared with the Extended Kalman Filter(EKF)-based method,and better accuracy was easily found.The proposed parameter identification method has great applicability for structural objects with nonlinear behaviors and could be extended to research in other engineering fields.展开更多
The observations of dislocations, substructures and other microstructural details were conducted mainly by means of transmission electron microscope (TEM) and scanning electron microscope (SEM) for 12CrlMoV pearlitic ...The observations of dislocations, substructures and other microstructural details were conducted mainly by means of transmission electron microscope (TEM) and scanning electron microscope (SEM) for 12CrlMoV pearlitic heat-resistant steel. It is shown that during the high temperature long-term aging, the disordered and jumbled phase-transformed dislocations caused by normalized cooling are recovered and rearranged into cell substructures, and then the dislocation density is reduced gradually. Finally a low density linear dislocation configuration and a stabler dislocation network are formed and ferritic grains grow considerably.展开更多
A numerical analysis using a finite element program was performed on three structures： hot mix asphalt （HMA） reinforced trackbed （RACS-1）, HMA directly supported trackbed （RACS-2）, and traditional Portland Ceme...A numerical analysis using a finite element program was performed on three structures： hot mix asphalt （HMA） reinforced trackbed （RACS-1）, HMA directly supported trackbed （RACS-2）, and traditional Portland Cement Concrete （PCC） slab track （SlabTrack）. Although the comprehensive dynamic responses of RACS-1 were similar with SlabTrack, HMA layer can positively affect the stress distributions. In particular, the horizontal stresses indicate that the resilience of RACS-1 was improved relative to SlabTrack. In addition, HMA reinforced substructure has the capacity to recover the residual vertical deformation. The effective depth for weakening dynamic loadings is mainly from 0 to 2 m, this being especially true at 0.5 m. The results from the analysis show that HMA is a suitable material for the railway substructure to enhance resilient performance, improve the stress distribution, weaken dynamic loading, and lower the vibration, especially at the effective depth of 2 m. The HMA constructed at the top of the stone subbase layer allows the vertical modulus a smooth transition. In terms of the comprehensive dynamic behaviors, RACS-1 is better than SlabTrack, while the results for RACS-2 are inconclusive and require further research.展开更多
This paper presents an innovative eccentric jacket substructure for offshore wind turbines to better withstand intense environmental forces and to replace conventional X-braced jackets in seismically active areas. The...This paper presents an innovative eccentric jacket substructure for offshore wind turbines to better withstand intense environmental forces and to replace conventional X-braced jackets in seismically active areas. The proposed eccentric jacket comprises of completely overlapped joint at every joint connection. The joint consists of a chord and two braces in a single plane. The two braces are fully overlapped with a short segment of the diagonal brace welded directly onto the chord. The characteristic feature of this joint configuration is that the short segment member can be designed to absorb and dissipate energy under cyclic load excitation. The experimental and numerical study revealed that the completely overlapped joint performed better in terms of strength resistance, stiffness, ductility, and energy absorption capacity than the conventional gap joints commonly found in typical X-braced jacket framings. The eccentric jacket could also be designed to becoming less stiff, with an inelastic yielding and local buckling of short segment member, so as to better resist the cyclic load generated from intense environmental forces and earthquake. From the design economics, the eccentric jacket provided a more straightforward fabrication with reduced number of welded joints and shorter thicker wall cans than the conventional X-braced jacket. It can therefore be concluded based on the results presented in the study that by designing the short segment member in accordance with strength and ductility requirement,the eccentric jacket substructure supporting the wind turbine could be made to remain stable under gravity loads and to sustain a significantly large amount of motion in the event of rare and intense earthquake or environmental forces, without collapsing.展开更多
The spray-deposition was used to produce billets of Mg-4Al-1.5Zn-3Ca-1Nd(A alloy)and Mg-13Al-3Zn-3Ca-1Nd(B alloy),and evolution of deformation substructure and Mg_(x)Zn_(y)Ca_(z)metastable phase in fine-grained(3μm)M...The spray-deposition was used to produce billets of Mg-4Al-1.5Zn-3Ca-1Nd(A alloy)and Mg-13Al-3Zn-3Ca-1Nd(B alloy),and evolution of deformation substructure and Mg_(x)Zn_(y)Ca_(z)metastable phase in fine-grained(3μm)Mg alloys was investigated by scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD),and electron backscattered diffraction(EBSD).It was found that different dislocation configurations were formed in A and B alloys.Redundant free dislocations(RFDs)and dislocation tangles were the ways to form deformation substructure in A alloy,no RFDs except dislocation tangles were found in B alloy.The interaction between nano-scale second phase particles(nano-scale C15 andβ-Mg_(17)(Al,Zn)_(12)phase)and different dislocation configurations had a significant effect on the deformation substructures formation.The mass transfer of Mg_(x)Zn_(y)Ca_(z)metastable phases and the stacking order of stacking faults were conducive to the Mg-Nd-Zn typed long period stacking ordered(LPSO)phases formation.Nano-scale C15 phases,Mg-Nd-Zn typed LPSO phases,c/a ratio,β-Mg_(17)(Al,Zn)_(12)phases were the key factors influencing the formation of textures.Different textures and grain boundary features(GB features)had a significant effect on k-value.The non-basal textures were the main factor affecting k-value in A alloy,while the high-angle grain boundary(HAGB)was the main factor affecting k-value in B alloy.展开更多
We carry out a detailed study of medium modifications on Z^(0)/γ+hadron correlations as well as jet substructures in association with Z^(0)/γ in Pb+Pb collisions with √S_(NN)=5.02TeV at the LHC.We utilize the linea...We carry out a detailed study of medium modifications on Z^(0)/γ+hadron correlations as well as jet substructures in association with Z^(0)/γ in Pb+Pb collisions with √S_(NN)=5.02TeV at the LHC.We utilize the linear Boltzmann transport(LBT)model to simulate the jet-medium interactions and medium response,and an extended cluster hadronization model to investigate the nonperturbative transition of quarks and gluons into final hadrons in heavy-ion collisions.Including hadronization effect,we can well describe Z^(0)/γ+hadrons correlations and Z^(0)/γ-tagged jet substructures in both p+p and Pb+Pb collisions simultaneously.Medium modification on jet profile and jet fragmentation functions indicate that particles carrying a large fraction of the jet momentum are generally closely aligned with the jet axis,whereas low-momentum particles are observed to have a much broader angular distribution relative to jet axis in Pb+Pb collisions due to jet-medium interactions.In particular,we find that Z^(0)/γ-tagged hadron correlations are sensitive to the soft particles from the dense medium and medium response,while jet-substructures show weak dependence on those soft hadrons with only a fraction of them falling inside the jet area.展开更多
Finding the common substructures shared by two proteins is considered as one of the central issues in computational biology because of its usefulness in understanding the structure-function relationship and applicatio...Finding the common substructures shared by two proteins is considered as one of the central issues in computational biology because of its usefulness in understanding the structure-function relationship and application in drug and vaccine design. In this paper, we propose a novel algorithm called FAMCS （Finding All Maximal Common Substructures） for the common substructure identification problem. Our method works initially at the protein secondary structural element （SSE） level and starts with the identification of all structurally similar SSE pairs. These SSE pairs are then merged into sets using a modified Apriori algorithm, which will test the similarity of various sets of SSE pairs incrementally until all the maximal sets of SSE pairs that deemed to be similar are found. The maximal common substructures of the two proteins will be formed from these maximal sets. A refinement algorithm is also proposed to fine tune the alignment from the SSE level to the residue level. Comparison of FAMCS with other methods on various proteins shows that FAMCS can address all four requirements and infer interesting biological discoveries.展开更多
A data-driven model ofmultiple variable cutting(M-VCUT)level set-based substructure is proposed for the topology optimization of lattice structures.TheM-VCUTlevel setmethod is used to represent substructures,enriching...A data-driven model ofmultiple variable cutting(M-VCUT)level set-based substructure is proposed for the topology optimization of lattice structures.TheM-VCUTlevel setmethod is used to represent substructures,enriching their diversity of configuration while ensuring connectivity.To construct the data-driven model of substructure,a database is prepared by sampling the space of substructures spanned by several substructure prototypes.Then,for each substructure in this database,the stiffness matrix is condensed so that its degrees of freedomare reduced.Thereafter,the data-drivenmodel of substructures is constructed through interpolationwith compactly supported radial basis function(CS-RBF).The inputs of the data-driven model are the design variables of topology optimization,and the outputs are the condensed stiffness matrix and volume of substructures.During the optimization,this data-driven model is used,thus avoiding repeated static condensation that would requiremuch computation time.Several numerical examples are provided to verify the proposed method.展开更多
Facing the high demand for faster and heavier freight trains in Australia,researchers and practitioners are endeavouring to develop more innovative and resilient ballasted tracks.In recent years,many studies have been...Facing the high demand for faster and heavier freight trains in Australia,researchers and practitioners are endeavouring to develop more innovative and resilient ballasted tracks.In recent years,many studies have been conducted by the researchers from Transport Research Centre at the University of Technology Sydney(TRC-UTS)to examine the feasibility of incorporating recycled tyre/rubber into rail tracks.This paper reviews three innovative applications using recycled rubber products such as(1)a synthetic energy-absorbing layer for railway subballast using a composite of rubber crumbs and mining byproducts,(2)using rubber intermixed ballast stratum to replace conventional ballast,and(3)installing recycled rubber mat to mitigate ballast degradation under the impact loading.Comprehensive laboratory and field tests as well as numerical modelling have been conducted to examine the performance of rail tracks incorporating these innovative inclusions.The laboratory and field test results and numerical modelling reveal that incorporating these rubber products could increase the energy-absorbing capacity of the track,and mitigate the ballast breakage and settlement significantly,hence increasing the track stability.The research outcomes will facilitate a better understanding of the performance of ballast tracks incorporating these resilient waste tyre materials while promoting more economical and environmentally sustainable tracks for greater passenger comfort and increased safety.展开更多
Ti-Zr-Nb refractory multi-principal element alloys(RMPEAs)have attracted increased attention due to their excellent mechanical properties.In this study,(TiZr)_(80-x)Nb_(20)Mo_(x)(x=0,5 and 10)alloys were designed,and ...Ti-Zr-Nb refractory multi-principal element alloys(RMPEAs)have attracted increased attention due to their excellent mechanical properties.In this study,(TiZr)_(80-x)Nb_(20)Mo_(x)(x=0,5 and 10)alloys were designed,and the intrinsic conflicts between strength and ductility were overcome via composition optimization and recrystallization.The causes of the superior strength-ductility synergy were investigated in terms of their deformation mechanism and dislocation behavior.The results show that the strength improvement can be attributed to the deformation mechanism transition caused by local chemical fluctuations and lattice distortion.Specifically,the slip band widths decrease after Mo addition,and the measured slip traces in the fracture samples are associated with high-order{112}and{123}slip planes.Furthermore,the grain refinement achieved via recrystallization promotes multi-slip system activation and shortens the slip-band spacing,which reduces the stress concentration and inhibits crack source formation,thereby allowing the alloy to ensure sufficient ductility.Consequently,the Ti_(35)Zr_(35)Nb_(20)Mo_(10)alloy annealed at 900℃ exhibits high yield strength and elongation.These findings provide a new strategy for designing high-strength RMPEAs and addressing room-temperature brittleness.展开更多
Using a substructure synthesis method this paper studies the longitudinal compressive impact of a flexible bar with a rigid body. The crucial variable affecting the validity of the method is derived theoretically. By ...Using a substructure synthesis method this paper studies the longitudinal compressive impact of a flexible bar with a rigid body. The crucial variable affecting the validity of the method is derived theoretically. By computational simulation tests, excellent agreement has been found be-tween the solution of this model and the exact solution when the variable is chosen suitably. Con-sidering both the computational efficiency and the accuracy of solutions obtained on the model in different engineering problems, several optimum values of the variable are suggested.展开更多
Structural elucidation (automatic determination of the structure of amolecule from its spectra) is frequently hampered by combinatorial explosion when trying to assemblethe identified substructures. We devised a new m...Structural elucidation (automatic determination of the structure of amolecule from its spectra) is frequently hampered by combinatorial explosion when trying to assemblethe identified substructures. We devised a new method which can avoid this pitfall by a systematicexamination of allowed ^(13)C chemical shifts ranges for all substructures chemically possible andcombined with a progressive pruning thanks to neighbouring relationships appearing from 2D NMR. Thismethod is explained by a detailed example.展开更多
Considering the pivotal role of single-wavelength anomalous diffraction(SAD) in macromolecular crystallography,our objective was to introduce DSAS,a novel program designed for efficient anomalous scattering substructu...Considering the pivotal role of single-wavelength anomalous diffraction(SAD) in macromolecular crystallography,our objective was to introduce DSAS,a novel program designed for efficient anomalous scattering substructure determination.DSAS stands out with its core components:a modified phase-retrieval algorithm and automated parameter tuning.The software boasts an intuitive graphical user interface(GUI),facilitating seamless input of essential data and real-time monitoring.Extensive testing on DSAS has involved diverse datasets,encompassing proteins,nucleic acids,and various anomalous scatters such as sulfur(S),selenium(Se),metals,and halogens.The results confirm DSAS’s exceptional performance in accurately determining heavy atom positions,making it a highly effective tool in the field.展开更多
For real-time dynamic substructure testing(RTDST),the influence of the inertia force of fluid specimens on the stability and accuracy of the integration algorithms has never been investigated.Therefore,this study prop...For real-time dynamic substructure testing(RTDST),the influence of the inertia force of fluid specimens on the stability and accuracy of the integration algorithms has never been investigated.Therefore,this study proposes to investigate the stability and accuracy of the central difference method(CDM)for RTDST considering the specimen mass participation coefficient.First,the theory of the CDM for RTDST is presented.Next,the stability and accuracy of the CDM for RTDST considering the specimen mass participation coefficient are investigated.Finally,numerical simulations and experimental tests are conducted for verifying the effectiveness of the method.The study indicates that the stability of the algorithm is affected by the mass participation coefficient of the specimen,and the stability limit first increases and then decreases as the mass participation coefficient increases.In most cases,the mass participation coefficient will increase the stability limit of the algorithm,but in specific circumstances,the algorithm may lose its stability.The stability and accuracy of the CDM considering the mass participation coefficient are verified by numerical simulations and experimental tests on a three-story frame structure with a tuned liquid damper.展开更多
This paper presents a new computational method for forward uncertainty quantification(UQ)analyses on large-scale structural systems in the presence of arbitrary and dependent random inputs.The method consists of a gen...This paper presents a new computational method for forward uncertainty quantification(UQ)analyses on large-scale structural systems in the presence of arbitrary and dependent random inputs.The method consists of a generalized polynomial chaos expansion(GPCE)for statistical moment and reliability analyses associated with the stochastic output and a static reanalysis method to generate the input-output data set.In the reanalysis,we employ substructuring for a structure to isolate its local regions that vary due to random inputs.This allows for avoiding repeated computations of invariant substructures while generating the input-output data set.Combining substructuring with static condensation further improves the computational efficiency of the reanalysis without losing accuracy.Consequently,the GPCE with the static reanalysis method can achieve significant computational saving,thus mitigating the curse of dimensionality to some degree for UQ under high-dimensional inputs.The numerical results obtained from a simple structure indicate that the proposed method for UQ produces accurate solutions more efficiently than the GPCE using full finite element analyses(FEAs).We also demonstrate the efficiency and scalability of the proposed method by executing UQ for a large-scale wing-box structure under ten-dimensional(all-dependent)random inputs.展开更多
The Al-9Zn-2.8Mg-2.5Cu-xZr-ySc alloys （x=0, 0.15%, 0.15%; y=0, 0.05%, 0.15%）, produced by low-frequent electromagnetic casting technology, were subjected to homogenization treatment, hot extrusion, solution and agin...The Al-9Zn-2.8Mg-2.5Cu-xZr-ySc alloys （x=0, 0.15%, 0.15%; y=0, 0.05%, 0.15%）, produced by low-frequent electromagnetic casting technology, were subjected to homogenization treatment, hot extrusion, solution and aging treatment. The effects of minor Sc and Zr addition on microstructure, recrystallization and properties of alloys were studied by optical microscopy （OM）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The results show that Sc and Zr addition can refine grains of the as-cast alloy by precipitation of primary Al3（Sc,Zr） particles formed during solidification as heterogeneous nuclei. Secondary Al3（Sc,Zr） precipitates formed during homogenization treatment strongly pin the movement of dislocation and subgrain boundaries, which can effectively inhibit the alloys recrystallization. Compared with the alloy without Sc and Zr addition, the Al-Zn-Mg-Cu-Zr alloy with 0.05%Sc and 0.15%Zr shows the increase in tensile strength and yield strength by 172 MPa and 218 MPa, respectively. Strengthening comes from the contributions of precipitation, substructure and grain refining.展开更多
基金Projects(50574091,50774084) supported by the National Natural Science Foundation of China
文摘A feasible method to improve the reliability and processing efficiency of large vibrating screen via the application of an elastic screen surface with multiple attached substructures （ESSMAS） was proposed. In the ESSMAS, every screen rod, with ends embedded into elastomer, is coupled to the main screen structure in a relatively flexible manner. The theoretical analysis was conducted, which consists of establishing dynamic model promoted from the fuzzy structure theory as well as calculating for the equivalent stiffness of each attached structure. According to the numerical simulation using the NEWMARK-fl integration method, this assembling pattern significantly leads to the screen surface/rod having larger vibration intensity than that of the corresponding position on screen structure, which specifically, with an averaged acceleration amplitude increasing ratio of 11.37% in theoretical analysis and 20.27% in experimental test. The experimental results, within a tolerant error, also confirm the established model and demonstrate the feasibility of ESSMAS.
基金This research is supported by the National Natural Science Foundation of China(11790282,U1534204,11472179)the Natural Science Foundation of Hebei Province(A2016210099).
文摘A crystal-plasticity cyclic constitutive model of polycrystalline material considering intra-granular heterogeneous dislocation substructures,in terms of three dislocation categories:mobile dislocations,immobile dislocations in the cell interiors and in the cell walls,is proposed based on the existing microscopic and macroscopic experimental results.The multiplication,annihilation,rearrangement and immobilization of dislocations on each slip system are taken as the basic evolutionary mechanism of the three dislocation categories,and the cross-slip of screw dislocations is viewed as the dynamic recovery mechanism at room temperature.The slip resistance associated with the isotropic hardening rule results from the interactions of dislocations on the slip systems.Meanwhile,a modified nonlinear kinematic hardening rule and a rate-dependent flow rule at the slip system level are employed to improve the predictive capability of the model for ratchetting deformation.The predictive ability of the developed model to uniaxial and mul-tiaxial ratchetting in macroscopic scale is verified by comparing with the experimental results of polycrystalline 316L stainless steel.The ratchetting in intra-granular scale which is obviously dependent on the crystallographic orientation and stress levels can be reasonably predicted by the proposed model.
文摘BACKGROUND Radiation dose to specific cardiac substructures can have a significant on treatment related morbidity and mortality,yet definition of these structures is labor intensive and not standard.Autosegmentation software may potentially address these issues,however it is unclear whether this approach can be broadly applied across different treatment planning conditions.We investigated the feasibility of autosegmentation of the cardiac substructures in four-dimensional(4D)computed tomography(CT),respiratory-gated,non-contrasted imaging.AIM To determine whether autosegmentation can be successfully employed on 4DCT respiratory-gated,non-contrasted imaging.METHODS We included patients who underwent stereotactic body radiation therapy for inoperable,early-stage non-small cell lung cancer from 2007 to 2019.All patients were simulated via 4DCT imaging with respiratory gating without intravenous contrast.Generated structure quality was evaluated by degree of required manual edits and volume discrepancy between the autocontoured structures and its edited sister structure.RESULTS Initial 17-structure cardiac atlas was generated with 20 patients followed by three successive iterations of 10 patients using MIM software.The great vessels and heart chambers were reliably autosegmented with most edits considered minor.In contrast,coronary arteries either failed to be autosegmented or the generated structures required major alterations necessitating deletion and manual definition.Similarly,the generated mitral and tricuspid valves were poor whereas the aortic and pulmonary valves required at least minor and moderate changes respectively.For the majority of subsites,the additional samples did not appear to substantially impact the quality of generated structures.Volumetric analysis between autosegmented and its manually edited sister structure yielded comparable findings to the physician-based assessment of structure quality.CONCLUSION The use of MIM software with 30-sample subject library was found to be useful in delineating many of the heart substructures with acceptable clinical accuracy on respiratory-gated 4DCT imaging.Small volume structures,such as the coronary arteries were poorly autosegmented and require manual definition.
基金National Natural Science Foundation of China under Grant Nos.61903009,51978016 and 61673002Beijing Municipal Education Commission under Grant No.KM201810011005。
文摘Combining the advantages of numerical simulation with experimental testing,real-time dynamic substructure(RTDS)testing provides a new experimental method for the investigation of engineered structures.However,not all unmodeled parts can be physically tested,as testing is often limited by the capacity of the test facility.Model updating is a good option to improve the modeling accuracy for numerical substructures in RTDS.In this study,a model updating method is introduced,which has great performance in describing this nonlinearity.In order to determine the optimal parameters in this model,an Unscented Kalman Filter(UKF)-based algorithm was applied to extract the knowledge contained in the sensors data.All the parameters that need to be identified are listed as the extended state variables,and the identification was achieved via the step-by-step state prediction and state update process.Effectiveness of the proposed method was verified through a group of experimental data,and results showed good agreement.Furthermore,the proposed method was compared with the Extended Kalman Filter(EKF)-based method,and better accuracy was easily found.The proposed parameter identification method has great applicability for structural objects with nonlinear behaviors and could be extended to research in other engineering fields.
基金supported by the Natural Science Foundation of Gansu Province(No.ZS001-A22-046-C).
文摘The observations of dislocations, substructures and other microstructural details were conducted mainly by means of transmission electron microscope (TEM) and scanning electron microscope (SEM) for 12CrlMoV pearlitic heat-resistant steel. It is shown that during the high temperature long-term aging, the disordered and jumbled phase-transformed dislocations caused by normalized cooling are recovered and rearranged into cell substructures, and then the dislocation density is reduced gradually. Finally a low density linear dislocation configuration and a stabler dislocation network are formed and ferritic grains grow considerably.
文摘A numerical analysis using a finite element program was performed on three structures： hot mix asphalt （HMA） reinforced trackbed （RACS-1）, HMA directly supported trackbed （RACS-2）, and traditional Portland Cement Concrete （PCC） slab track （SlabTrack）. Although the comprehensive dynamic responses of RACS-1 were similar with SlabTrack, HMA layer can positively affect the stress distributions. In particular, the horizontal stresses indicate that the resilience of RACS-1 was improved relative to SlabTrack. In addition, HMA reinforced substructure has the capacity to recover the residual vertical deformation. The effective depth for weakening dynamic loadings is mainly from 0 to 2 m, this being especially true at 0.5 m. The results from the analysis show that HMA is a suitable material for the railway substructure to enhance resilient performance, improve the stress distribution, weaken dynamic loading, and lower the vibration, especially at the effective depth of 2 m. The HMA constructed at the top of the stone subbase layer allows the vertical modulus a smooth transition. In terms of the comprehensive dynamic behaviors, RACS-1 is better than SlabTrack, while the results for RACS-2 are inconclusive and require further research.
文摘This paper presents an innovative eccentric jacket substructure for offshore wind turbines to better withstand intense environmental forces and to replace conventional X-braced jackets in seismically active areas. The proposed eccentric jacket comprises of completely overlapped joint at every joint connection. The joint consists of a chord and two braces in a single plane. The two braces are fully overlapped with a short segment of the diagonal brace welded directly onto the chord. The characteristic feature of this joint configuration is that the short segment member can be designed to absorb and dissipate energy under cyclic load excitation. The experimental and numerical study revealed that the completely overlapped joint performed better in terms of strength resistance, stiffness, ductility, and energy absorption capacity than the conventional gap joints commonly found in typical X-braced jacket framings. The eccentric jacket could also be designed to becoming less stiff, with an inelastic yielding and local buckling of short segment member, so as to better resist the cyclic load generated from intense environmental forces and earthquake. From the design economics, the eccentric jacket provided a more straightforward fabrication with reduced number of welded joints and shorter thicker wall cans than the conventional X-braced jacket. It can therefore be concluded based on the results presented in the study that by designing the short segment member in accordance with strength and ductility requirement,the eccentric jacket substructure supporting the wind turbine could be made to remain stable under gravity loads and to sustain a significantly large amount of motion in the event of rare and intense earthquake or environmental forces, without collapsing.
基金financial support by the National Natural Science Foundation of China(No.51364032)the Inner Mongolia Natural Science Foundation(No.2022MS05028)。
文摘The spray-deposition was used to produce billets of Mg-4Al-1.5Zn-3Ca-1Nd(A alloy)and Mg-13Al-3Zn-3Ca-1Nd(B alloy),and evolution of deformation substructure and Mg_(x)Zn_(y)Ca_(z)metastable phase in fine-grained(3μm)Mg alloys was investigated by scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD),and electron backscattered diffraction(EBSD).It was found that different dislocation configurations were formed in A and B alloys.Redundant free dislocations(RFDs)and dislocation tangles were the ways to form deformation substructure in A alloy,no RFDs except dislocation tangles were found in B alloy.The interaction between nano-scale second phase particles(nano-scale C15 andβ-Mg_(17)(Al,Zn)_(12)phase)and different dislocation configurations had a significant effect on the deformation substructures formation.The mass transfer of Mg_(x)Zn_(y)Ca_(z)metastable phases and the stacking order of stacking faults were conducive to the Mg-Nd-Zn typed long period stacking ordered(LPSO)phases formation.Nano-scale C15 phases,Mg-Nd-Zn typed LPSO phases,c/a ratio,β-Mg_(17)(Al,Zn)_(12)phases were the key factors influencing the formation of textures.Different textures and grain boundary features(GB features)had a significant effect on k-value.The non-basal textures were the main factor affecting k-value in A alloy,while the high-angle grain boundary(HAGB)was the main factor affecting k-value in B alloy.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2020B0301030008)the National Natural Science Foundation of China(Grant Nos.12147131,11935007,12035007,and 12022512)supported by the MOE Key Laboratory of Quark and Lepton Physics(CCNU)(Grant No.QLPL2021P01)。
文摘We carry out a detailed study of medium modifications on Z^(0)/γ+hadron correlations as well as jet substructures in association with Z^(0)/γ in Pb+Pb collisions with √S_(NN)=5.02TeV at the LHC.We utilize the linear Boltzmann transport(LBT)model to simulate the jet-medium interactions and medium response,and an extended cluster hadronization model to investigate the nonperturbative transition of quarks and gluons into final hadrons in heavy-ion collisions.Including hadronization effect,we can well describe Z^(0)/γ+hadrons correlations and Z^(0)/γ-tagged jet substructures in both p+p and Pb+Pb collisions simultaneously.Medium modification on jet profile and jet fragmentation functions indicate that particles carrying a large fraction of the jet momentum are generally closely aligned with the jet axis,whereas low-momentum particles are observed to have a much broader angular distribution relative to jet axis in Pb+Pb collisions due to jet-medium interactions.In particular,we find that Z^(0)/γ-tagged hadron correlations are sensitive to the soft particles from the dense medium and medium response,while jet-substructures show weak dependence on those soft hadrons with only a fraction of them falling inside the jet area.
文摘Finding the common substructures shared by two proteins is considered as one of the central issues in computational biology because of its usefulness in understanding the structure-function relationship and application in drug and vaccine design. In this paper, we propose a novel algorithm called FAMCS （Finding All Maximal Common Substructures） for the common substructure identification problem. Our method works initially at the protein secondary structural element （SSE） level and starts with the identification of all structurally similar SSE pairs. These SSE pairs are then merged into sets using a modified Apriori algorithm, which will test the similarity of various sets of SSE pairs incrementally until all the maximal sets of SSE pairs that deemed to be similar are found. The maximal common substructures of the two proteins will be formed from these maximal sets. A refinement algorithm is also proposed to fine tune the alignment from the SSE level to the residue level. Comparison of FAMCS with other methods on various proteins shows that FAMCS can address all four requirements and infer interesting biological discoveries.
基金supported by the National Natural Science Foundation of China(Grant No.12272144).
文摘A data-driven model ofmultiple variable cutting(M-VCUT)level set-based substructure is proposed for the topology optimization of lattice structures.TheM-VCUTlevel setmethod is used to represent substructures,enriching their diversity of configuration while ensuring connectivity.To construct the data-driven model of substructure,a database is prepared by sampling the space of substructures spanned by several substructure prototypes.Then,for each substructure in this database,the stiffness matrix is condensed so that its degrees of freedomare reduced.Thereafter,the data-drivenmodel of substructures is constructed through interpolationwith compactly supported radial basis function(CS-RBF).The inputs of the data-driven model are the design variables of topology optimization,and the outputs are the condensed stiffness matrix and volume of substructures.During the optimization,this data-driven model is used,thus avoiding repeated static condensation that would requiremuch computation time.Several numerical examples are provided to verify the proposed method.
基金financial support from the Australian Research Council for ARCLP200200915 and ARCDP220102862financial and technical support from industry partners including Sydney Trains,SMEC Australia Pty.
文摘Facing the high demand for faster and heavier freight trains in Australia,researchers and practitioners are endeavouring to develop more innovative and resilient ballasted tracks.In recent years,many studies have been conducted by the researchers from Transport Research Centre at the University of Technology Sydney(TRC-UTS)to examine the feasibility of incorporating recycled tyre/rubber into rail tracks.This paper reviews three innovative applications using recycled rubber products such as(1)a synthetic energy-absorbing layer for railway subballast using a composite of rubber crumbs and mining byproducts,(2)using rubber intermixed ballast stratum to replace conventional ballast,and(3)installing recycled rubber mat to mitigate ballast degradation under the impact loading.Comprehensive laboratory and field tests as well as numerical modelling have been conducted to examine the performance of rail tracks incorporating these innovative inclusions.The laboratory and field test results and numerical modelling reveal that incorporating these rubber products could increase the energy-absorbing capacity of the track,and mitigate the ballast breakage and settlement significantly,hence increasing the track stability.The research outcomes will facilitate a better understanding of the performance of ballast tracks incorporating these resilient waste tyre materials while promoting more economical and environmentally sustainable tracks for greater passenger comfort and increased safety.
基金supported by the National Key Research and Development Program of China(No.2022YFF0609000)the National Natural Science Foundation of China(Nos.52171034 and 52101037)the Postdoctoral Fellowship Program of CPSF(No.GZB20230944).
文摘Ti-Zr-Nb refractory multi-principal element alloys(RMPEAs)have attracted increased attention due to their excellent mechanical properties.In this study,(TiZr)_(80-x)Nb_(20)Mo_(x)(x=0,5 and 10)alloys were designed,and the intrinsic conflicts between strength and ductility were overcome via composition optimization and recrystallization.The causes of the superior strength-ductility synergy were investigated in terms of their deformation mechanism and dislocation behavior.The results show that the strength improvement can be attributed to the deformation mechanism transition caused by local chemical fluctuations and lattice distortion.Specifically,the slip band widths decrease after Mo addition,and the measured slip traces in the fracture samples are associated with high-order{112}and{123}slip planes.Furthermore,the grain refinement achieved via recrystallization promotes multi-slip system activation and shortens the slip-band spacing,which reduces the stress concentration and inhibits crack source formation,thereby allowing the alloy to ensure sufficient ductility.Consequently,the Ti_(35)Zr_(35)Nb_(20)Mo_(10)alloy annealed at 900℃ exhibits high yield strength and elongation.These findings provide a new strategy for designing high-strength RMPEAs and addressing room-temperature brittleness.
基金supported by the National Natural Science Foundation of China (Grant No. 19832040) and Specialized Research Fund for the Doctoral Program of Higher Education (Grant No. 2000024818)
文摘Using a substructure synthesis method this paper studies the longitudinal compressive impact of a flexible bar with a rigid body. The crucial variable affecting the validity of the method is derived theoretically. By computational simulation tests, excellent agreement has been found be-tween the solution of this model and the exact solution when the variable is chosen suitably. Con-sidering both the computational efficiency and the accuracy of solutions obtained on the model in different engineering problems, several optimum values of the variable are suggested.
文摘Structural elucidation (automatic determination of the structure of amolecule from its spectra) is frequently hampered by combinatorial explosion when trying to assemblethe identified substructures. We devised a new method which can avoid this pitfall by a systematicexamination of allowed ^(13)C chemical shifts ranges for all substructures chemically possible andcombined with a progressive pruning thanks to neighbouring relationships appearing from 2D NMR. Thismethod is explained by a detailed example.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.32371280 and T2350011)。
文摘Considering the pivotal role of single-wavelength anomalous diffraction(SAD) in macromolecular crystallography,our objective was to introduce DSAS,a novel program designed for efficient anomalous scattering substructure determination.DSAS stands out with its core components:a modified phase-retrieval algorithm and automated parameter tuning.The software boasts an intuitive graphical user interface(GUI),facilitating seamless input of essential data and real-time monitoring.Extensive testing on DSAS has involved diverse datasets,encompassing proteins,nucleic acids,and various anomalous scatters such as sulfur(S),selenium(Se),metals,and halogens.The results confirm DSAS’s exceptional performance in accurately determining heavy atom positions,making it a highly effective tool in the field.
基金National Natural Science Foundation of China under Grant Nos.51978213 and 51778190the National Key Research and Development Program of China under Grant Nos.2017YFC0703605 and 2016YFC0701106。
文摘For real-time dynamic substructure testing(RTDST),the influence of the inertia force of fluid specimens on the stability and accuracy of the integration algorithms has never been investigated.Therefore,this study proposes to investigate the stability and accuracy of the central difference method(CDM)for RTDST considering the specimen mass participation coefficient.First,the theory of the CDM for RTDST is presented.Next,the stability and accuracy of the CDM for RTDST considering the specimen mass participation coefficient are investigated.Finally,numerical simulations and experimental tests are conducted for verifying the effectiveness of the method.The study indicates that the stability of the algorithm is affected by the mass participation coefficient of the specimen,and the stability limit first increases and then decreases as the mass participation coefficient increases.In most cases,the mass participation coefficient will increase the stability limit of the algorithm,but in specific circumstances,the algorithm may lose its stability.The stability and accuracy of the CDM considering the mass participation coefficient are verified by numerical simulations and experimental tests on a three-story frame structure with a tuned liquid damper.
基金Project supported by the National Research Foundation of Korea(Nos.NRF-2020R1C1C1011970 and NRF-2018R1A5A7023490)。
文摘This paper presents a new computational method for forward uncertainty quantification(UQ)analyses on large-scale structural systems in the presence of arbitrary and dependent random inputs.The method consists of a generalized polynomial chaos expansion(GPCE)for statistical moment and reliability analyses associated with the stochastic output and a static reanalysis method to generate the input-output data set.In the reanalysis,we employ substructuring for a structure to isolate its local regions that vary due to random inputs.This allows for avoiding repeated computations of invariant substructures while generating the input-output data set.Combining substructuring with static condensation further improves the computational efficiency of the reanalysis without losing accuracy.Consequently,the GPCE with the static reanalysis method can achieve significant computational saving,thus mitigating the curse of dimensionality to some degree for UQ under high-dimensional inputs.The numerical results obtained from a simple structure indicate that the proposed method for UQ produces accurate solutions more efficiently than the GPCE using full finite element analyses(FEAs).We also demonstrate the efficiency and scalability of the proposed method by executing UQ for a large-scale wing-box structure under ten-dimensional(all-dependent)random inputs.
基金Project(0211002605132)supported by Institute of Multipurpose Utilization of Mineral Resources,Chinese Academy of Geological Sciences,ChinaProject(0211005303101)supported by the Fundamental Research Funds for the Central Universities,China+1 种基金Project(2010BB4074)supported by Natural Science Foundation Project of CQ CSTC,ChinaProject(2010ZD-02)supported by State Key Laboratory for Advanced Metals and Materials,China
文摘The Al-9Zn-2.8Mg-2.5Cu-xZr-ySc alloys （x=0, 0.15%, 0.15%; y=0, 0.05%, 0.15%）, produced by low-frequent electromagnetic casting technology, were subjected to homogenization treatment, hot extrusion, solution and aging treatment. The effects of minor Sc and Zr addition on microstructure, recrystallization and properties of alloys were studied by optical microscopy （OM）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The results show that Sc and Zr addition can refine grains of the as-cast alloy by precipitation of primary Al3（Sc,Zr） particles formed during solidification as heterogeneous nuclei. Secondary Al3（Sc,Zr） precipitates formed during homogenization treatment strongly pin the movement of dislocation and subgrain boundaries, which can effectively inhibit the alloys recrystallization. Compared with the alloy without Sc and Zr addition, the Al-Zn-Mg-Cu-Zr alloy with 0.05%Sc and 0.15%Zr shows the increase in tensile strength and yield strength by 172 MPa and 218 MPa, respectively. Strengthening comes from the contributions of precipitation, substructure and grain refining.
