Based on the Timoshenko beam theory,this paper proposes a nonlocal bi-gyroscopic model for spinning functionally graded(FG)nanotubes conveying fluid,and the thermal–mechanical vibration and stability of such composit...Based on the Timoshenko beam theory,this paper proposes a nonlocal bi-gyroscopic model for spinning functionally graded(FG)nanotubes conveying fluid,and the thermal–mechanical vibration and stability of such composite nanostructures under small scale,rotor,and temperature coupling effects are investigated.The nanotube is composed of functionally graded materials(FGMs),and different volume fraction functions are utilized to control the distribution of material properties.Eringen’s nonlocal elasticity theory and Hamilton’s principle are applied for dynamical modeling,and the forward and backward precession frequencies as well as 3D mode configurations of the nanotube are obtained.By conducting dimensionless analysis,it is found that compared to the Timoshenko nano-beam model,the conventional Euler–Bernoulli(E-B)model holds the same flutter frequency in the supercritical region,while it usually overestimates the higher-order precession frequencies.The nonlocal,thermal,and flowing effects all can lead to buckling or different kinds of coupled flutter in the system.The material distribution of the P-type FGM nanotube can also induce coupled flutter,while that of the S-type FGM nanotube has no impact on the stability of the system.This paper is expected to provide a theoretical foundation for the design of motional composite nanodevices.展开更多
BACKGROUND Despite the promising prospects of using artificial intelligence and machine learning(ML)for disease classification and prediction purposes,the complexity and lack of explainability of this method make it d...BACKGROUND Despite the promising prospects of using artificial intelligence and machine learning(ML)for disease classification and prediction purposes,the complexity and lack of explainability of this method make it difficult to apply the constructed models in clinical practice.We developed and validated an interpretable ML model based on magnetic resonance imaging(MRI)radiomics and clinical features for the preoperative prediction of the pathological grades of hepatocellular carcinomas(HCCs).This model will help clinicians better understand the situation and develop personalized treatment plans.AIM To develop and validate an interpretable ML model for preoperative pathological grade prediction in HCC patients via a combination of multisequence MRI radiomics and clinical features.METHODS MRI and clinical data derived from 125 patients with HCCs confirmed by postoperative pathological examinations were retrospectively analyzed.The patients were randomly split into training and validation groups(7:3 ratio).Univariate and multivariate logistic regression analyses were performed to identify independent clinical predictors.The tumor lesions observed on axial fatsuppressed T2-weighted imaging(FS-T2WI),arterial phase(AP),and portal venous phase(PVP)images were delineated in a slice-by-slice manner using 3D-slicer to generate volumetric regions of interest,and radiomic features were extracted.Interclass correlation coefficients were calculated,and least absolute selection and shrinkage operator regression were conducted for feature selection purposes.Six predictive models were subsequently developed for pathological grade prediction:FS-T2WI,AP,PVP,integrated radiomics,clinical,and combined radiomics-clinical(RC)models.The effectiveness of these models was assessed by calculating their area under the receiver operating characteristic curve(AUC)values.The clinical applicability of the models was evaluated via decision curve analysis.Finally,the contributions of the different features contained in the model with optimal performance were interpreted via a SHapley Additive exPlanations analysis.RESULTS Among the 125 patients,87 were assigned to the training group,and 38 were assigned to the validation group.The maximum tumor diameter,hepatitis B virus status,and monocyte count were identified as independent predictors of pathological grade.Twelve optimal radiomic features were ultimately selected.The AUC values obtained for the FS-T2WI model,AP model,PVP model,radiomics model,clinical model,and combined RC model in the training group were 0.761[95%confidence interval(CI):0.562-0.857],0.870(95%CI:0.714-0.918),0.868(95%CI:0.714-0.959),0.917(95%CI:0.857-0.959),0.869(95%CI:0.643-0.973),and 0.941(95%CI:0.857-0.945),respectively;in the validation group,the AUC values were 0.724(95%CI:0.625-0.833),0.802(95%CI:0.686-1.000),0.797(95%CI:0.688-1.000),0.901(95%CI:0.833-0.906),0.865(95%CI:0.594-1.000),and 0.932(95%CI:0.812-1.000),respectively.The combined RC model demonstrated the best performance.Additionally,the decision curve analysis revealed that the combined RC model had satisfactory prediction efficiency,and the SHapley Additive exPlanations value analysis revealed that the“FS-T2WI-wavelet-HLL_gldm_Large Dependence High Gray Level Emphasis”feature contributed the most to the model,exhibiting a positive effect.CONCLUSION An interpretable ML model based on MRI radiomics provides a noninvasive tool for predicting the pathological grade of HCCs,which will help clinicians develop personalized treatment plans.展开更多
This paper extends the one-dimensional(1D)nonlocal strain gradient integral model(NStraGIM)to the two-dimensional(2D)Kirchhoff axisymmetric nanoplates,based on nonlocal strain gradient integral relations formulated al...This paper extends the one-dimensional(1D)nonlocal strain gradient integral model(NStraGIM)to the two-dimensional(2D)Kirchhoff axisymmetric nanoplates,based on nonlocal strain gradient integral relations formulated along both the radial and circumferential directions.By transforming the proposed integral constitutive equations into the equivalent differential forms,complemented by the corresponding constitutive boundary conditions(CBCs),a well-posed mathematical formulation is established for analyzing the axisymmetric bending and buckling of annular/circular functionally graded(FG)sandwich nanoplates.The boundary conditions at the inner edge of a solid nanoplate are derived by L'H?spital's rule.The numerical solution is obtained by the generalized differential quadrature method(GDQM).The accuracy of the proposed model is validated through comparison with the data from the existing literature.A parameter study is conducted to demonstrate the effects of FG sandwich parameters,size parameters,and nonlocal gradient parameters.展开更多
From the process of sedimentation the mathematical relationships among deposition Volume and powder properties as well as sedimentation parameters were deduced. Based on the formula a mathematical model was set up and...From the process of sedimentation the mathematical relationships among deposition Volume and powder properties as well as sedimentation parameters were deduced. Based on the formula a mathematical model was set up and simulated through the computer. At last the validity of mathematical model was supported by the representative experiment on Ti-Mo system FGM prepared by co-sedimentation.展开更多
This paper presents a hybrid graded element model for the transient heat conduction problem in functionally graded materials （FGMs）. First, a Laplace transform approach is used to handle the time variable. Then, a f...This paper presents a hybrid graded element model for the transient heat conduction problem in functionally graded materials （FGMs）. First, a Laplace transform approach is used to handle the time variable. Then, a fundamental solution in Laplace space for FGMs is constructed. Next, a hybrid graded element is formulated based on the obtained fundamental solution and a frame field. As a result, the graded properties of FGMs are naturally reflected by using the fundamental solution to interpolate the intra-element field. Further, Stefest＇s algorithm is employed to convert the results in Laplace space back into the time-space domain. Finally, the performance of the proposed method is assessed by several benchmark examples. The results demonstrate well the efficiency and accuracy of the proposed method.展开更多
We present a study on the dynamic stability of porous functionally graded(PFG)beams under hygro-thermal loading.The variations of the properties of the beams across the beam thicknesses are described by the power-law ...We present a study on the dynamic stability of porous functionally graded(PFG)beams under hygro-thermal loading.The variations of the properties of the beams across the beam thicknesses are described by the power-law model.Unlike most studies on this topic,we consider both the bending deformation of the beams and the hygro-thermal load as size-dependent,simultaneously,by adopting the equivalent differential forms of the well-posed nonlocal strain gradient integral theory(NSGIT)which are strictly equipped with a set of constitutive boundary conditions(CBCs),and through which both the stiffness-hardening and stiffness-softening effects of the structures can be observed with the length-scale parameters changed.All the variables presented in the differential problem formulation are discretized.The numerical solution of the dynamic instability region(DIR)of various bounded beams is then developed via the generalized differential quadrature method(GDQM).After verifying the present formulation and results,we examine the effects of different parameters such as the nonlocal/gradient length-scale parameters,the static force factor,the functionally graded(FG)parameter,and the porosity parameter on the DIR.Furthermore,the influence of considering the size-dependent hygro-thermal load is also presented.展开更多
Grade-tonnage model is one of the research frontiers of systematical exploration theory. Based on the “Reserve Database of Mineral Resources in China (1997)”, this paper establishes the geological model, grade model...Grade-tonnage model is one of the research frontiers of systematical exploration theory. Based on the “Reserve Database of Mineral Resources in China (1997)”, this paper establishes the geological model, grade model, tonnage model, grade-tonnage model and tonnage-sequence model of contact metasomatic copper deposits in China. The mathematical properties of these models are described in detail.展开更多
A grade-tonnage model is established according to the analysis of 72 porphyry copper deposits recorded in 'The Mineral Resources Data Base of China'. Based on the analysis of frequency histogram, the cumulativ...A grade-tonnage model is established according to the analysis of 72 porphyry copper deposits recorded in 'The Mineral Resources Data Base of China'. Based on the analysis of frequency histogram, the cumulative frequency distributing graph and the theoretical model with double logarithmic coordinates of copper deposits, the typical mathematical characteristics of grade-tonnage model of porphyry copper deposits are clarified.展开更多
According to grade-tonnage diagrams of nickel and zinc deposits, their critical grades are 0.4 % and 3. 4 %, respectively, and hence the former resources can be considered optimistic and the latter pessimistic. The gr...According to grade-tonnage diagrams of nickel and zinc deposits, their critical grades are 0.4 % and 3. 4 %, respectively, and hence the former resources can be considered optimistic and the latter pessimistic. The grade-tonnage diagram of gold deposits is convex downwards suggesting that the critical grade is 1 X 10-6 in the low-grade part. The ore value (OV)-tonnage diagram of all deposits In the world consists of three parts: high, middle and low vain f classes. The enrichment ratio (ER)-tonnage diagram of all deposits in the world ho consists of three parts: high, middle and low ratio classes.Nine quality categories defined by ER and OV are characterized by some keywords indicating deposit types as follows: category RH (high ER-high OV: 0. 7 %) by 'unconformity' and 'Mississippi Val-ley', category HM (high ER-middle: OV: 0.7 %) by 'vein', category ML (middle ER-low OV: 0 %) by 'sandstone', 'stockwork' and' dissemination', category LM by 'orthomagmatic',' laterite',komatiite and ' chemical', and category LL by 'porphyry', 'dissemination' and 'placer'. Category MM is not characterized by any keyword. If the commodities of a deposit are defined by both the enrichment ratio and the ore value, the defined commodities are relatively coincident for gold and nickel,but different for copper, silver and zinc, and greatly different for molybdenum and lead. Deposits containing lead and/or zinc are complimentary. If the commodity Ph+Zn is applied, most lead or zinc deposits are classified as Ph+Zu by both definitions. Accessory metals are commonly expected for deposits of kuroko-type zinc, epithermal silver, massive sulfide-type zinc and volcanogenic zinc, but uncommon for deposits of orthomagmatic chromium, chemically precipitated copper and sandstone-type uranium.展开更多
The authors have studied the statistical characteristics of China＇s molybdenum deposits to establish the grade-tonnage model based on the data updated to the end of 2010. The results showed that each type of China＇s...The authors have studied the statistical characteristics of China＇s molybdenum deposits to establish the grade-tonnage model based on the data updated to the end of 2010. The results showed that each type of China＇s molybdenum deposits complied with Lasky＇s law approximately and the characteristics of grade-tonnage model obey the lognormal distribution. However, there are poor correlations between grade and tonnage respectively. Ultimately, we aimed to fit the grade-tonnage model through the known distribution function, draw the cumulative probability curves, and evaluated undiscovered mineral resources of China＇s molybdenum deposits by means of Monte Carlo simulation integrated in MRAS.展开更多
Due to the importance of detecting the matte grade in the copper flash smelting process, the mechanism model was established according to the multi-phase and multi-component mathematic model. Meanwhile this procedure ...Due to the importance of detecting the matte grade in the copper flash smelting process, the mechanism model was established according to the multi-phase and multi-component mathematic model. Meanwhile this procedure was a complicated production process with characteristics of large time delay, nonlinearity and so on. A fuzzy neural network model was set up through a great deal of production data. Besides a novel constrained gradient descent algorithm used to update the parameters was put forward to improve the parameters learning efficiency. Ultimately the self-adaptive combination technology was adopted to paralleled integrate two models in order to obtain the prediction model of the matte grade. Industrial data validation shows that the intelligently integrated model is more precise than a single model. It can not only predict the matte grade exactly but also provide optimal control of the copper flash smelting process with potent guidance.展开更多
How to query Linked Data effectively is a challenge due to its heterogeneous datasets.There are three types of heterogeneities,i.e.,different structures representing entities,different predicates with the same meaning...How to query Linked Data effectively is a challenge due to its heterogeneous datasets.There are three types of heterogeneities,i.e.,different structures representing entities,different predicates with the same meaning and different literal formats used in objects.Approaches based on ontology mapping or Information Retrieval(IR) cannot deal with all types of heterogeneities.Facing these limitations,we propose a hierarchical multi-hop language model(HMPM).It discriminates among three types of predicates,descriptive predicates,out-associated predicates and in-associated predicates,and generates multi-hop models for them respectively.All predicates' similarities between the query and entity are organized into a hierarchy,with predicate types on the first level and predicates of this type on the second level.All candidates are ranked in ascending order.We evaluated HMPM in three datasets,DBpedia,Linked MDB and Yago.The results of experiments show that the effectiveness and generality of HMPM outperform the existing approaches.展开更多
The Federal Railroad Administration (FRA)’s Web Based Accident Prediction System (WBAPS) is used by federal, state and local agencies to get a preliminary idea on safety at a rail-highway grade crossing. It is an int...The Federal Railroad Administration (FRA)’s Web Based Accident Prediction System (WBAPS) is used by federal, state and local agencies to get a preliminary idea on safety at a rail-highway grade crossing. It is an interactive and user-friendly tool used to make funding decisions. WBAPS is almost three decades old and involves a three-step approach making it difficult to interpret the contribution of the variables included in the model. It also does not directly account for regional/local developments and technological advancements pertaining to signals and signs implemented at rail-highway grade crossings. Further, characteristics of a rail-highway grade crossing vary by track class which is not explicitly considered by WBAPS. This research, therefore, examines and develops a method and models to estimate crashes at rail-highway grade crossings by track class using regional/local level data. The method and models developed for each track class as well as considering all track classes together are based on data for the state of North Carolina. Linear, as well as count models based on Poisson and Negative Binomial (NB) distributions, was tested for applicability. Negative binomial models were found to be the best fit for the data used in this research. Models for each track class have better goodness of fit statistics compared to the model considering data for all track classes together. This is primarily because traffic, design, and operational characteristics at rail-highway grade crossings are different for each track class. The findings from statistical models in this research are supported by model validation.展开更多
To further increase the throughput of wireless multi-hop networks,a distributed scheduling method is proposed,which takes physical interference model into account.It is assumed that nodes in the network can perform ph...To further increase the throughput of wireless multi-hop networks,a distributed scheduling method is proposed,which takes physical interference model into account.It is assumed that nodes in the network can perform physical carrier sensing,and the carrier sensing range can be set to different values.In the traditional carrier sensing mechanism,the carrier sensing range is computed under the protocol interference model,which is not accurate.Here the optimal carrier sensing range with physical interference model is achieved.Each sending node implements the distributed approach in three phases at each time slot,and all the concurrent transmissions are interference free.Good performance can be achieved under this scheduling approach.The approximation ratio of the distributed method to the optimal one is also proved.展开更多
In this paper,a multiscale model is developed for the mass functionally graded(FG)beam-fluid system to investigate its static and dynamic responses based on 3D printed porous beam free vibration tests,which are determ...In this paper,a multiscale model is developed for the mass functionally graded(FG)beam-fluid system to investigate its static and dynamic responses based on 3D printed porous beam free vibration tests,which are determined by two aspects.At the microstructural level,the gradient variation is realized by arbitrary distribution of matrix pores,and the effective moduli under specific distribution are obtained using the micromechanics homogenization theory.In the meantime,at the structural level,the mechanical responses of FG porous beams subjected to mass loading are considered in a static fluid environment.Then,the explicit expressions of local finite-element(FE)expressions corresponding to the static and dynamic responses are given in the appendices.The present results are validated against numerical and experimental results from the literature and mechanical tests of 3D printed structures,with good agreement generally obtained,giving credence to the present model.On this basis,a comprehensive parametric study is carried out,with a particular focus on the effects of boundary conditions,fluid density,and slenderness ratio on the bending and vibration of FG beams with several different gradations.展开更多
Mortars provide the continuity required for the stability and exclusion of weather elements in masonry assemblies. But because of the heterogeneity of the mortar, its mechanism of behaviour under different load effect...Mortars provide the continuity required for the stability and exclusion of weather elements in masonry assemblies. But because of the heterogeneity of the mortar, its mechanism of behaviour under different load effects is dependent on the properties of the constituents of the mortar. The aim of paper is to determine the effect sand grading for various cement-sand-lime mortar designations (BS) and strength classes (EC) on the compressive strength and stiffness of mortar. Two silica sands;HST 95 and HST60 were used to make mortars in three strength classes: M2, M4 and M6, corresponding to mortar designations iv, iii and ii respectively. The results show that mortar made with the HST60 sand (coarser grading) usually resulted in mortar with a higher compressive strength and stiffness. The One Way ANOVA analysis of both compressive strength and stiffness at a significance level of 5% on the effect of sand grading on the two parameters also shows that they are both significant. There is also strong evidence of a linear correlation between the stiffness and compressive strength. The results indicate that in order to replicate full scale behaviour of masonry at model scales, the grading of fine aggregate in the models should be similar so as to properly model full scale behavior.展开更多
The accurate evaluation of a course determines the quality of learning and is the basis for evaluating the students' academic achievements. This paper, on the theoretical basis of grade point, builds a dynamic str...The accurate evaluation of a course determines the quality of learning and is the basis for evaluating the students' academic achievements. This paper, on the theoretical basis of grade point, builds a dynamic stratified GPA (Grade Point Average) evaluation model for the course Automotive Electrical System Diagnosis, focuses on the whole process assessment and aims to stimulate the enthusiasm of learning to meet the demands of the training of social skilled talents.展开更多
The combination of online teaching and traditional offline teaching can maximize the advantages of both.Based on the blended teaching of English Reading course,39 students were selected as the research subjects to stu...The combination of online teaching and traditional offline teaching can maximize the advantages of both.Based on the blended teaching of English Reading course,39 students were selected as the research subjects to study the relationship between their online learning attitudes and their grades in the final examination.Judged from the number of times for each student to download teaching resources,the number of assignments submitted online,and the quality of the submitted assignments,each student’s attitude toward online learning was examined comprehensively,and a correlation analysis was conducted through SPSS Statistics 21.0 to explore the influence of online learning attitude on English reading performance.Through data collection and analysis of the online learning attitudes over a 16-week period,a significant positive correlation was found between the online learning attitudes and the English reading grades,indicating that the online learning attitude in the blended learning model plays a crucial role in improving the English reading skill,and students should maintain a positive attitude toward online teaching in blended learning.展开更多
基金National Natural Science Foundation of China,12372025,Feng Liang,12072311,Feng Liang.
文摘Based on the Timoshenko beam theory,this paper proposes a nonlocal bi-gyroscopic model for spinning functionally graded(FG)nanotubes conveying fluid,and the thermal–mechanical vibration and stability of such composite nanostructures under small scale,rotor,and temperature coupling effects are investigated.The nanotube is composed of functionally graded materials(FGMs),and different volume fraction functions are utilized to control the distribution of material properties.Eringen’s nonlocal elasticity theory and Hamilton’s principle are applied for dynamical modeling,and the forward and backward precession frequencies as well as 3D mode configurations of the nanotube are obtained.By conducting dimensionless analysis,it is found that compared to the Timoshenko nano-beam model,the conventional Euler–Bernoulli(E-B)model holds the same flutter frequency in the supercritical region,while it usually overestimates the higher-order precession frequencies.The nonlocal,thermal,and flowing effects all can lead to buckling or different kinds of coupled flutter in the system.The material distribution of the P-type FGM nanotube can also induce coupled flutter,while that of the S-type FGM nanotube has no impact on the stability of the system.This paper is expected to provide a theoretical foundation for the design of motional composite nanodevices.
文摘BACKGROUND Despite the promising prospects of using artificial intelligence and machine learning(ML)for disease classification and prediction purposes,the complexity and lack of explainability of this method make it difficult to apply the constructed models in clinical practice.We developed and validated an interpretable ML model based on magnetic resonance imaging(MRI)radiomics and clinical features for the preoperative prediction of the pathological grades of hepatocellular carcinomas(HCCs).This model will help clinicians better understand the situation and develop personalized treatment plans.AIM To develop and validate an interpretable ML model for preoperative pathological grade prediction in HCC patients via a combination of multisequence MRI radiomics and clinical features.METHODS MRI and clinical data derived from 125 patients with HCCs confirmed by postoperative pathological examinations were retrospectively analyzed.The patients were randomly split into training and validation groups(7:3 ratio).Univariate and multivariate logistic regression analyses were performed to identify independent clinical predictors.The tumor lesions observed on axial fatsuppressed T2-weighted imaging(FS-T2WI),arterial phase(AP),and portal venous phase(PVP)images were delineated in a slice-by-slice manner using 3D-slicer to generate volumetric regions of interest,and radiomic features were extracted.Interclass correlation coefficients were calculated,and least absolute selection and shrinkage operator regression were conducted for feature selection purposes.Six predictive models were subsequently developed for pathological grade prediction:FS-T2WI,AP,PVP,integrated radiomics,clinical,and combined radiomics-clinical(RC)models.The effectiveness of these models was assessed by calculating their area under the receiver operating characteristic curve(AUC)values.The clinical applicability of the models was evaluated via decision curve analysis.Finally,the contributions of the different features contained in the model with optimal performance were interpreted via a SHapley Additive exPlanations analysis.RESULTS Among the 125 patients,87 were assigned to the training group,and 38 were assigned to the validation group.The maximum tumor diameter,hepatitis B virus status,and monocyte count were identified as independent predictors of pathological grade.Twelve optimal radiomic features were ultimately selected.The AUC values obtained for the FS-T2WI model,AP model,PVP model,radiomics model,clinical model,and combined RC model in the training group were 0.761[95%confidence interval(CI):0.562-0.857],0.870(95%CI:0.714-0.918),0.868(95%CI:0.714-0.959),0.917(95%CI:0.857-0.959),0.869(95%CI:0.643-0.973),and 0.941(95%CI:0.857-0.945),respectively;in the validation group,the AUC values were 0.724(95%CI:0.625-0.833),0.802(95%CI:0.686-1.000),0.797(95%CI:0.688-1.000),0.901(95%CI:0.833-0.906),0.865(95%CI:0.594-1.000),and 0.932(95%CI:0.812-1.000),respectively.The combined RC model demonstrated the best performance.Additionally,the decision curve analysis revealed that the combined RC model had satisfactory prediction efficiency,and the SHapley Additive exPlanations value analysis revealed that the“FS-T2WI-wavelet-HLL_gldm_Large Dependence High Gray Level Emphasis”feature contributed the most to the model,exhibiting a positive effect.CONCLUSION An interpretable ML model based on MRI radiomics provides a noninvasive tool for predicting the pathological grade of HCCs,which will help clinicians develop personalized treatment plans.
基金Project supported by the National Natural Science Foundation of China(No.12172169)the Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘This paper extends the one-dimensional(1D)nonlocal strain gradient integral model(NStraGIM)to the two-dimensional(2D)Kirchhoff axisymmetric nanoplates,based on nonlocal strain gradient integral relations formulated along both the radial and circumferential directions.By transforming the proposed integral constitutive equations into the equivalent differential forms,complemented by the corresponding constitutive boundary conditions(CBCs),a well-posed mathematical formulation is established for analyzing the axisymmetric bending and buckling of annular/circular functionally graded(FG)sandwich nanoplates.The boundary conditions at the inner edge of a solid nanoplate are derived by L'H?spital's rule.The numerical solution is obtained by the generalized differential quadrature method(GDQM).The accuracy of the proposed model is validated through comparison with the data from the existing literature.A parameter study is conducted to demonstrate the effects of FG sandwich parameters,size parameters,and nonlocal gradient parameters.
文摘From the process of sedimentation the mathematical relationships among deposition Volume and powder properties as well as sedimentation parameters were deduced. Based on the formula a mathematical model was set up and simulated through the computer. At last the validity of mathematical model was supported by the representative experiment on Ti-Mo system FGM prepared by co-sedimentation.
文摘This paper presents a hybrid graded element model for the transient heat conduction problem in functionally graded materials （FGMs）. First, a Laplace transform approach is used to handle the time variable. Then, a fundamental solution in Laplace space for FGMs is constructed. Next, a hybrid graded element is formulated based on the obtained fundamental solution and a frame field. As a result, the graded properties of FGMs are naturally reflected by using the fundamental solution to interpolate the intra-element field. Further, Stefest＇s algorithm is employed to convert the results in Laplace space back into the time-space domain. Finally, the performance of the proposed method is assessed by several benchmark examples. The results demonstrate well the efficiency and accuracy of the proposed method.
基金Project supported by the National Natural Science Foundation of China(No.12172169)the Natural Sciences and Engineering Research Council of Canada(No.NSERC RGPIN-2023-03227)。
文摘We present a study on the dynamic stability of porous functionally graded(PFG)beams under hygro-thermal loading.The variations of the properties of the beams across the beam thicknesses are described by the power-law model.Unlike most studies on this topic,we consider both the bending deformation of the beams and the hygro-thermal load as size-dependent,simultaneously,by adopting the equivalent differential forms of the well-posed nonlocal strain gradient integral theory(NSGIT)which are strictly equipped with a set of constitutive boundary conditions(CBCs),and through which both the stiffness-hardening and stiffness-softening effects of the structures can be observed with the length-scale parameters changed.All the variables presented in the differential problem formulation are discretized.The numerical solution of the dynamic instability region(DIR)of various bounded beams is then developed via the generalized differential quadrature method(GDQM).After verifying the present formulation and results,we examine the effects of different parameters such as the nonlocal/gradient length-scale parameters,the static force factor,the functionally graded(FG)parameter,and the porosity parameter on the DIR.Furthermore,the influence of considering the size-dependent hygro-thermal load is also presented.
基金National Doctoral Fund Project!(98024004)fund project of the L aboratoryofQuantitativePredictionExploration Assessment
文摘Grade-tonnage model is one of the research frontiers of systematical exploration theory. Based on the “Reserve Database of Mineral Resources in China (1997)”, this paper establishes the geological model, grade model, tonnage model, grade-tonnage model and tonnage-sequence model of contact metasomatic copper deposits in China. The mathematical properties of these models are described in detail.
文摘A grade-tonnage model is established according to the analysis of 72 porphyry copper deposits recorded in 'The Mineral Resources Data Base of China'. Based on the analysis of frequency histogram, the cumulative frequency distributing graph and the theoretical model with double logarithmic coordinates of copper deposits, the typical mathematical characteristics of grade-tonnage model of porphyry copper deposits are clarified.
基金the Grand-in-Aid for Scientific Research (No. 10041136) from Ministry of Education of Japan.
文摘According to grade-tonnage diagrams of nickel and zinc deposits, their critical grades are 0.4 % and 3. 4 %, respectively, and hence the former resources can be considered optimistic and the latter pessimistic. The grade-tonnage diagram of gold deposits is convex downwards suggesting that the critical grade is 1 X 10-6 in the low-grade part. The ore value (OV)-tonnage diagram of all deposits In the world consists of three parts: high, middle and low vain f classes. The enrichment ratio (ER)-tonnage diagram of all deposits in the world ho consists of three parts: high, middle and low ratio classes.Nine quality categories defined by ER and OV are characterized by some keywords indicating deposit types as follows: category RH (high ER-high OV: 0. 7 %) by 'unconformity' and 'Mississippi Val-ley', category HM (high ER-middle: OV: 0.7 %) by 'vein', category ML (middle ER-low OV: 0 %) by 'sandstone', 'stockwork' and' dissemination', category LM by 'orthomagmatic',' laterite',komatiite and ' chemical', and category LL by 'porphyry', 'dissemination' and 'placer'. Category MM is not characterized by any keyword. If the commodities of a deposit are defined by both the enrichment ratio and the ore value, the defined commodities are relatively coincident for gold and nickel,but different for copper, silver and zinc, and greatly different for molybdenum and lead. Deposits containing lead and/or zinc are complimentary. If the commodity Ph+Zn is applied, most lead or zinc deposits are classified as Ph+Zu by both definitions. Accessory metals are commonly expected for deposits of kuroko-type zinc, epithermal silver, massive sulfide-type zinc and volcanogenic zinc, but uncommon for deposits of orthomagmatic chromium, chemically precipitated copper and sandstone-type uranium.
基金funded by the National Natural Science Foundation of China (No.41002119)China Geological Survey (No. 1212010733806)the Basic Scientific Research Funds of the China Central Non-Commercial Institutes (No. K1103)
文摘The authors have studied the statistical characteristics of China＇s molybdenum deposits to establish the grade-tonnage model based on the data updated to the end of 2010. The results showed that each type of China＇s molybdenum deposits complied with Lasky＇s law approximately and the characteristics of grade-tonnage model obey the lognormal distribution. However, there are poor correlations between grade and tonnage respectively. Ultimately, we aimed to fit the grade-tonnage model through the known distribution function, draw the cumulative probability curves, and evaluated undiscovered mineral resources of China＇s molybdenum deposits by means of Monte Carlo simulation integrated in MRAS.
基金Project(60634020) supported by the National Natural Science Foundation of ChinaProject(2002CB312200) supported by the National Basic Research and Development Program of China
文摘Due to the importance of detecting the matte grade in the copper flash smelting process, the mechanism model was established according to the multi-phase and multi-component mathematic model. Meanwhile this procedure was a complicated production process with characteristics of large time delay, nonlinearity and so on. A fuzzy neural network model was set up through a great deal of production data. Besides a novel constrained gradient descent algorithm used to update the parameters was put forward to improve the parameters learning efficiency. Ultimately the self-adaptive combination technology was adopted to paralleled integrate two models in order to obtain the prediction model of the matte grade. Industrial data validation shows that the intelligently integrated model is more precise than a single model. It can not only predict the matte grade exactly but also provide optimal control of the copper flash smelting process with potent guidance.
文摘How to query Linked Data effectively is a challenge due to its heterogeneous datasets.There are three types of heterogeneities,i.e.,different structures representing entities,different predicates with the same meaning and different literal formats used in objects.Approaches based on ontology mapping or Information Retrieval(IR) cannot deal with all types of heterogeneities.Facing these limitations,we propose a hierarchical multi-hop language model(HMPM).It discriminates among three types of predicates,descriptive predicates,out-associated predicates and in-associated predicates,and generates multi-hop models for them respectively.All predicates' similarities between the query and entity are organized into a hierarchy,with predicate types on the first level and predicates of this type on the second level.All candidates are ranked in ascending order.We evaluated HMPM in three datasets,DBpedia,Linked MDB and Yago.The results of experiments show that the effectiveness and generality of HMPM outperform the existing approaches.
文摘The Federal Railroad Administration (FRA)’s Web Based Accident Prediction System (WBAPS) is used by federal, state and local agencies to get a preliminary idea on safety at a rail-highway grade crossing. It is an interactive and user-friendly tool used to make funding decisions. WBAPS is almost three decades old and involves a three-step approach making it difficult to interpret the contribution of the variables included in the model. It also does not directly account for regional/local developments and technological advancements pertaining to signals and signs implemented at rail-highway grade crossings. Further, characteristics of a rail-highway grade crossing vary by track class which is not explicitly considered by WBAPS. This research, therefore, examines and develops a method and models to estimate crashes at rail-highway grade crossings by track class using regional/local level data. The method and models developed for each track class as well as considering all track classes together are based on data for the state of North Carolina. Linear, as well as count models based on Poisson and Negative Binomial (NB) distributions, was tested for applicability. Negative binomial models were found to be the best fit for the data used in this research. Models for each track class have better goodness of fit statistics compared to the model considering data for all track classes together. This is primarily because traffic, design, and operational characteristics at rail-highway grade crossings are different for each track class. The findings from statistical models in this research are supported by model validation.
基金Supported by the National Basic Research Program of China(No.2007CB307105)the National Natural Science Foundation of China(No.60932005)
文摘To further increase the throughput of wireless multi-hop networks,a distributed scheduling method is proposed,which takes physical interference model into account.It is assumed that nodes in the network can perform physical carrier sensing,and the carrier sensing range can be set to different values.In the traditional carrier sensing mechanism,the carrier sensing range is computed under the protocol interference model,which is not accurate.Here the optimal carrier sensing range with physical interference model is achieved.Each sending node implements the distributed approach in three phases at each time slot,and all the concurrent transmissions are interference free.Good performance can be achieved under this scheduling approach.The approximation ratio of the distributed method to the optimal one is also proved.
基金supported by the National Key Research and Development Program of China(No.2020YFA0711700)the National Natural Science Foundation of China(No.12322206,No.52378158,No.12302205)ZJU-ZCCC Institute of Collaborative Innovation(No.ZDJG2021002).
文摘In this paper,a multiscale model is developed for the mass functionally graded(FG)beam-fluid system to investigate its static and dynamic responses based on 3D printed porous beam free vibration tests,which are determined by two aspects.At the microstructural level,the gradient variation is realized by arbitrary distribution of matrix pores,and the effective moduli under specific distribution are obtained using the micromechanics homogenization theory.In the meantime,at the structural level,the mechanical responses of FG porous beams subjected to mass loading are considered in a static fluid environment.Then,the explicit expressions of local finite-element(FE)expressions corresponding to the static and dynamic responses are given in the appendices.The present results are validated against numerical and experimental results from the literature and mechanical tests of 3D printed structures,with good agreement generally obtained,giving credence to the present model.On this basis,a comprehensive parametric study is carried out,with a particular focus on the effects of boundary conditions,fluid density,and slenderness ratio on the bending and vibration of FG beams with several different gradations.
文摘Mortars provide the continuity required for the stability and exclusion of weather elements in masonry assemblies. But because of the heterogeneity of the mortar, its mechanism of behaviour under different load effects is dependent on the properties of the constituents of the mortar. The aim of paper is to determine the effect sand grading for various cement-sand-lime mortar designations (BS) and strength classes (EC) on the compressive strength and stiffness of mortar. Two silica sands;HST 95 and HST60 were used to make mortars in three strength classes: M2, M4 and M6, corresponding to mortar designations iv, iii and ii respectively. The results show that mortar made with the HST60 sand (coarser grading) usually resulted in mortar with a higher compressive strength and stiffness. The One Way ANOVA analysis of both compressive strength and stiffness at a significance level of 5% on the effect of sand grading on the two parameters also shows that they are both significant. There is also strong evidence of a linear correlation between the stiffness and compressive strength. The results indicate that in order to replicate full scale behaviour of masonry at model scales, the grading of fine aggregate in the models should be similar so as to properly model full scale behavior.
文摘The accurate evaluation of a course determines the quality of learning and is the basis for evaluating the students' academic achievements. This paper, on the theoretical basis of grade point, builds a dynamic stratified GPA (Grade Point Average) evaluation model for the course Automotive Electrical System Diagnosis, focuses on the whole process assessment and aims to stimulate the enthusiasm of learning to meet the demands of the training of social skilled talents.
文摘The combination of online teaching and traditional offline teaching can maximize the advantages of both.Based on the blended teaching of English Reading course,39 students were selected as the research subjects to study the relationship between their online learning attitudes and their grades in the final examination.Judged from the number of times for each student to download teaching resources,the number of assignments submitted online,and the quality of the submitted assignments,each student’s attitude toward online learning was examined comprehensively,and a correlation analysis was conducted through SPSS Statistics 21.0 to explore the influence of online learning attitude on English reading performance.Through data collection and analysis of the online learning attitudes over a 16-week period,a significant positive correlation was found between the online learning attitudes and the English reading grades,indicating that the online learning attitude in the blended learning model plays a crucial role in improving the English reading skill,and students should maintain a positive attitude toward online teaching in blended learning.
基金This work is supported by National Natural Science Foundation of China（No.79970025）, Hubei Provincial Department of Education Foundation under Grant No.2003X130, and Scientific Research Team of Wuhan Polytechnic University under Grant No.03-T-06.
