Recently,azobenzene-4,4'-dicarboxylic acid(ADCA)has been produced gradually for use as an organic synthesis or pharmaceutical intermediate due to its eminent performance.With large quantities put into application ...Recently,azobenzene-4,4'-dicarboxylic acid(ADCA)has been produced gradually for use as an organic synthesis or pharmaceutical intermediate due to its eminent performance.With large quantities put into application in the future,the thermal stability of this substance during storage,transportation,and use will become quite important.Thus,in this work,the thermal decomposition behavior,thermal decomposition kinetics,and thermal hazard of ADCA were investigated.Experiments were conducted by using a SENSYS evo DSC device.A combination of differential iso-conversion method,compensation parameter method,and nonlinear fitting evaluation were also used to analyze thermal kinetics and mechanism of ADCA decomposition.The results show that when conversion rate α increases,the activation energies of ADCA's first and main decomposition peaks fall.The amount of heat released during decomposition varies between 182.46 and 231.16 J·g^(-1).The proposed kinetic equation is based on the Avrami-Erofeev model,which is consistent with the decomposition progress.Applying the Frank-Kamenetskii model,a calculated self-accelerating decomposition temperature of 287.0℃is obtained.展开更多
The paper analyzes the factors influencing machine tool selection. By using fuzzy mathematics theory, we establish a theorietical model for optimal machine tool selection considering geometric features, clamping size,...The paper analyzes the factors influencing machine tool selection. By using fuzzy mathematics theory, we establish a theorietical model for optimal machine tool selection considering geometric features, clamping size, machining range, machining precision and surface roughness. By means of fuzzy comprehensive evaluation method, the membership degree of machine tool selection and the largest comprehensive evaluation index are determined. Then the reasonably automatic selection of machine tool is realized in the generative computer aided process planning （CAPP） system. Finally, the finite element model based on ABAQUS is established and the cutting process of machine tool is simulated. According to the theoretical and empirical cutting parameters and the curve of surface residual stress, the optimal cutting parameters can be determined.展开更多
Carbon fiber reinforced polymer(CFRP)are widely used in various fields because of their high strength,good toughness,and low density.However,owing to their unique forming process,some complex structures such as holes ...Carbon fiber reinforced polymer(CFRP)are widely used in various fields because of their high strength,good toughness,and low density.However,owing to their unique forming process,some complex structures such as holes and grooves cannot be formed directly.Therefore,traditional machining procedures are also required.The drilling process is one of the most common machining methods for CFRP holes,but owing to the complex structure and difficulty in processing CFRP,the quality of the drilling process is often challenging to guarantee.Moreover,the hole-forming defects also have complex forms and lack uniform evaluation indexes.This study summarizes the common orifice defects in the process of CFRP drilling,establishes a comprehensive evaluation method of orifice defects by introducing the relevant theory of the fuzzy complementary judgment matrix,and experimentally verifies the accuracy and reliability of this method.Then,based on the experimental results,a non-linear cutting parameter optimization model is established,which effectively suppresses the orifice defects to ensure the accuracy of the hole size,roundness,and hole wall roughness.The hole-forming quality is subsequently improved.The hole quality evaluation method proposed in this study reduced the dimension of the evaluation index to ensure relevance and effectiveness and improved the convenience of quality inspection and parameter optimization in actual production.展开更多
This paper studies the coupling mechanism between the nonlinear stiffness and damping coefficients of Active Elastic Support/Dry Friction Damper(AESDFD)and rotor system.First,parameters for evaluating the vibration re...This paper studies the coupling mechanism between the nonlinear stiffness and damping coefficients of Active Elastic Support/Dry Friction Damper(AESDFD)and rotor system.First,parameters for evaluating the vibration reduction characteristics are proposed to facilitate the design of the AESDFD.To achieve this,the nonlinear friction force is initially represented as equivalent stiffness and damping coefficients,based on the ball-plate friction model.Second,three evaluation parameters—optimal slipping displacement,loss factor,and controllability—are proposed to reveal the vibration reduction characteristics of the AESDFD,alongside determining the optimal normal force.Subsequently,the finite element method,in conjunction with the ball-plate friction model,is introduced to formulate the governing equation of a low-pressure rotor system equipped with AESDFDs.The steady-state responses of the AESDFDs-rotor system are solved using the harmonic balance method combined with an efficient iteration method.Finally,the solutions are validated on the AESDFDs-rotor system both numerically and experimentally.The results indicate that controllability effectively assesses the vibration reduction performance of the AESDFD and is relatively insensitive to variations in low normal force.Away from the critical speed,the AESDFD suppresses vibration by altering the resonance position of the rotor system through its stiffness coefficient.Near the critical speed,vibration reduction is achieved primarily through energy dissipation by the damping coefficient.If the loss factor is less than one,the stiffness coefficient can diminish the vibration reduction effect of the damping coefficient.Notably,the optimal normal force of the AESDFD achieves optimal vibration reduction effect.This study reveals that changes in rotor system unbalance do not affect the vibration reduction characteristics of the AESDFD,with the same upper limit to the vibration reduction effect of the AESDFD.展开更多
In order to improve the effectiveness of Fuzzy Synthetic Evaluation (FSE) models, a Parameter Correlation Analysis (PCA) was introduced into the FSE and a case study was carried out in the Naoli River in the Sanjiang ...In order to improve the effectiveness of Fuzzy Synthetic Evaluation (FSE) models, a Parameter Correlation Analysis (PCA) was introduced into the FSE and a case study was carried out in the Naoli River in the Sanjiang Plain, Northeast China. The basic principle of the PCA is that the pairs of parameters which are highly correlated and linear with each other would contribute the same information to an assessment and one of them should be eliminated. The method of the PCA is that a correlation relationship among candidate parameters is examined before the FSE. If there is an apparent nonlinear or curvilinear relationship between two parameters, then both will be retained; if the correlation is significant (p<0.01), and the scatter plot suggests a linear relationship, then one of them will be deleted. However, which one will be deleted? For solving this problem, a sensitivity test was conducted and the higher sensitivity parameters remained. The results indicate that the original data should be preprocessed through the PCA for redundancy and variability. The study shows that introducing the PCA into the FSE can simplify the FSE calculation process greatly, while the results have not been changed much.展开更多
The composition of the modern aerospace system becomes more and more complex.The performance degradation of any device in the system may cause it difficult for the whole system to keep normal working states.Therefore,...The composition of the modern aerospace system becomes more and more complex.The performance degradation of any device in the system may cause it difficult for the whole system to keep normal working states.Therefore,it is essential to evaluate the performance of complex aerospace systems.In this paper,the performance evaluation of complex aerospace systems is regarded as a Multi-Attribute Decision Analysis(MADA)problem.Based on the structure and working principle of the system,a new Evidential Reasoning(ER)based approach with uncertain parameters is proposed to construct a nonlinear optimization model to evaluate the system performance.In the model,the interval form is used to express the uncertainty,such as error in testing data and inaccuracy in expert knowledge.In order to analyze the subsystems that have a great impact on the performance of the system,the sensitivity analysis of the evaluation result is carried out,and the corresponding maintenance strategy is proposed.For a type of Inertial Measurement Unit(IMU)used in a rocket,the proposed method is employed to evaluate its performance.Then,the parameter sensitivity of the evaluation result is analyzed,and the main factors affecting the performance of IMU are obtained.Finally,the comparative study shows the effectiveness of the proposed method.展开更多
The statistical probability and their variation regularity of the measurable characteristic parameters in the CO 2 arc welding droplet short circuiting transfer process have been studied. The statistical analysis sh...The statistical probability and their variation regularity of the measurable characteristic parameters in the CO 2 arc welding droplet short circuiting transfer process have been studied. The statistical analysis shows that the sensitivity of each characteristic parameter with regard to the variation of the short circuiting transfer process is different. The sensitivity of 4 kinds among these characteristic parameters is more intense than that of the short circuiting transfer frequency. In order to take account of the synthetic influence of these characteristic parameters, by means of the characteristic parameters synthetic value, a quantitative evaluation function is built up to describe and evaluate the short circuiting transfer process of CO 2 arc welding in real time. The testing shows that the evaluation function can give a suitable synthetic valuation for the short circuiting transfer process with a variety of welding variables.展开更多
Delamination represents one of the most severe failure modes in composite laminates,especially when they are subjected to uniaxial compression loads.The evaluation of the delamination damage has always been an essenti...Delamination represents one of the most severe failure modes in composite laminates,especially when they are subjected to uniaxial compression loads.The evaluation of the delamination damage has always been an essential issue of composite laminates for durability and damage tolerance in engineering practice.Focusing on the most typical and representative elliptical delamination issue,an analytical model simultaneously considering the conservative buckling process and non-conservative delamination propagation process is implemented.Various computational cases considering different delamination depths,directions,aspect ratios,and areas are established,and the predicted results based on the analytical model are carefully compared.Effects of these geometrical delamination parameters on the buckling,delamination propagation,and failure behaviors of composite laminates are thoroughly analyzed,and innovative evaluation principles of the delamination damage have been concluded.It is found that the delamination area is the key factor that truly affecting the failure behaviors of delaminated composites,and the local/global buckling and failure loads show clear linearity with the delamination area,whilst the delamination depth and direction only have slight effects.展开更多
Research has shown that there has been a significant change in the quantitative relationship between urbanization and economic development over the past 50 years. As a result of this change, the Chenery model is no lo...Research has shown that there has been a significant change in the quantitative relationship between urbanization and economic development over the past 50 years. As a result of this change, the Chenery model is no longer capable of performing a comparative analysis of these parameters. We carried out a regression analysis of the normal form of the relation between urbanization and economic development on the basis of the Chenery model. We used empirical data from 149 countries and regions from 1990 to 2009 and adopted the double logarithmic model, introducing a time series variable for urbanization. From 1990 to 2009, with a per capita gross national income remaining between USD 1000 and 10,000, the urbanization rate changed from 17.78 to 60.36% and the relational matching data changed accordingly, although the upper limit of the rate of urbanization remained at about 75%. Urbanization in countries with a smaller population size was more affected by economic development than urbanization in countries with large and medium sized populations.展开更多
The evaluation problem with three-parameter interval grey number (T-PIGN) widely exists in real world. To select effective evaluation indicators of the problem, this paper puts forward evaluation index system selectio...The evaluation problem with three-parameter interval grey number (T-PIGN) widely exists in real world. To select effective evaluation indicators of the problem, this paper puts forward evaluation index system selection principle of T-PIGN based on distance entropy model, and gives out evaluation index system selection judgment criterion of T-PIGN. Furthermore, for the redundancy of evaluation index system with T-PIGN, a selection method of evaluation index system with T-PIGN is proposed. Finally, the applicability of the proposed method is verified by concrete examples.展开更多
An efficient procedure is used for explicit description and evaluation of uncertainty of earthquake parameters in the uniform catalog of earthquakes in Iran and neighboring regions.An inadequate number of local and re...An efficient procedure is used for explicit description and evaluation of uncertainty of earthquake parameters in the uniform catalog of earthquakes in Iran and neighboring regions.An inadequate number of local and regional seismographic stations,poor station distribution,and Inadequacy of velocity models have resulted in conspicuous uncertainty in different parameters of recorded events.In a comprehensive seismic hazard analysis such uncertainties should be considered.Uncertainty of magnitude and location of events are evaluated for three different time periods,namely,historical,early instrumental,and modern instrumental time periods,for which existing seismological information differ widely in quantity,quality,and type.It is concluded that an uncertainty of 0.2-0.3 units of magnitude and 10-15 km in epicenter determinations should be considered in the most favorable conditions.None of the hypocenters of earthquakes in Iran can be considered as reliable,unless supported by other information such as展开更多
A Z-parameter method is used to evaluate the damage process of HK40 austenitic steel. By using Z-parameter based on the Larson-Miller method, the nonlinear master curve of the log stress vs Larson-Miller parameter P c...A Z-parameter method is used to evaluate the damage process of HK40 austenitic steel. By using Z-parameter based on the Larson-Miller method, the nonlinear master curve of the log stress vs Larson-Miller parameter P can be expressed as： P=27.74-3.41gσ-0.032σ, and a family of curves parallel to the master curve can be written as： P=（27.74-Z）-3.41gσ-0.032σ, where Z represents the magnitude of the deviation from the master curve. According to the creep rupture data both from different segments of a serviced tube and from the same segment locations with different service time, the value of parameter Z has close relationship with the deterioration of creep rupture properties. The damage state of the samples is evaluated by monitoring the changes in natural frequency f and Young＇s modulus E, and the relationships between Z and the damage parameters are discussed.展开更多
Eleven evaluating parameters for rice core collection were assessed based on genotypic values and molecular marke＇ information. Monte Carlo simulation combined with mixed linear model was used to eliminate the interf...Eleven evaluating parameters for rice core collection were assessed based on genotypic values and molecular marke＇ information. Monte Carlo simulation combined with mixed linear model was used to eliminate the interference from environment in order to draw more reliable results. The coincidence rate of range （CR） was the optimal parameter. Mean Simpson index （MD）, mean Shannon-Weaver index of genetic diversity （M1） and mean polymorphism information content （MPIC） were important evaluating parameters. The variable rate of coefficient of variation （VR） could act as an important reference parameter for evaluating the variation degree of core collection. Percentage of polymorphic loci （p） could be used as a determination parameter for the size of core collection. Mean difference percentage （MD） was a determination parameter for the reliability judgment of core collection. The effective evaluating parameters for core collection selected in the research could be used as criteria for sampling percentage in different plant germplasm populations.展开更多
A novel parameter is suggested for evaluating the fatigue crack growth rate in carbon steels. Fatigue crack propagation tests of an annealed 0.42% carbon steel were carried out under different conditions to investigat...A novel parameter is suggested for evaluating the fatigue crack growth rate in carbon steels. Fatigue crack propagation tests of an annealed 0.42% carbon steel were carried out under different conditions to investigate the relationship between this dominating parameter and the crack opening displacement (COD). A new equation of fatigue crack growth rate is formulated in terms of the suggested parameter. The physical meanings of the material parameters in this equation are explored experimentally. Considering the relation of crack growth and deformation properties, a simple and applicable method is proposed to evaluate the fatigue crack growth rate. It is also observed that the material parameters in the fatigue crack growth rate equation of carbon steels are related linearly to the material strength. The results are in a good agreement with experimental results.展开更多
Parameter inversions in oil/gas reservoirs based on well test interpretations are of great significance in oil/gas industry.Automatic well test interpretations based on artificial intelligence are the most promising t...Parameter inversions in oil/gas reservoirs based on well test interpretations are of great significance in oil/gas industry.Automatic well test interpretations based on artificial intelligence are the most promising to solve the problem of non-unique solution.In this work,a new deep reinforcement learning(DRL)based approach is proposed for automatic curve matching for well test interpretation,by using the double deep Q-network(DDQN).The DDQN algorithms are applied to train agents for automatic parameter tuning in three conventional well-testing models.In addition,to alleviate the dimensional disaster problem of parameter space,an asynchronous parameter adjustment strategy is used to train the agent.Finally,field applications are carried out by using the new DRL approaches.Results show that step number required for the DDQN to complete the curve matching is the least among,when comparing the naive deep Q-network(naive DQN)and deep Q-network(DQN).We also show that DDQN can improve the robustness of curve matching in comparison with supervised machine learning algorithms.Using DDQN algorithm to perform 100 curve matching tests on three traditional well test models,the results show that the mean relative error of the parameters is 7.58%for the homogeneous model,10.66%for the radial composite model,and 12.79%for the dual porosity model.In the actual field application,it is found that a good curve fitting can be obtained with only 30 steps of parameter adjustment.展开更多
relationships between logging data and reservoir parameters.We compare our method’s performances using two datasets and evaluate the influences of multi-task learning,model structure,transfer learning,and petrophysic...relationships between logging data and reservoir parameters.We compare our method’s performances using two datasets and evaluate the influences of multi-task learning,model structure,transfer learning,and petrophysics informed machine learning(PIML).Our experiments demonstrate that PIML significantly enhances the performance of formation evaluation,and the structure of residual neural network is optimal for incorporating petrophysical constraints.Moreover,PIML is less sensitive to noise.These findings indicate that it is crucial to integrate data-driven machine learning with petrophysical mechanism for the application of artificial intelligence in oil and gas exploration.展开更多
A comprehensive method to evaluate the factors affecting the production capacity of horizontal wells in Carboniferous volcanic rocks after fracturing is investigated.A systematic approach combining gray correlation an...A comprehensive method to evaluate the factors affecting the production capacity of horizontal wells in Carboniferous volcanic rocks after fracturing is investigated.A systematic approach combining gray correlation analysis,hierarchical analysis and fuzzy evaluation is proposed.In particular,first the incidence of reservoir properties and fracturing parameters on production capacity is assessed.These parameters include reservoir base geological parameters(porosity,permeability,oil saturation,waterproof height)as well as engineering parameters(fracture halflength,fracture height,fracture conductivity,fracture distance).Afterwards,a two-by-two comparison judgment matrix of sensitive parameters is constructed by means of hierarchical analysis,and the weighting coefficients of the factors are determined,where oil saturation,fracture conductivity and fracture half-length are weighted higher.Finally,the horizontal wells in the target block are categorized in terms of production capacity based on the fuzzy evaluation method,and split accordingly into high-producing,relatively high-producing,medium-producing and low-producing wells.Such a categorization is intended to provide parametric guidance for reservoir fracturing and modification.展开更多
When designing and optimizing the hull of vehicles,their sound quality needs to be considered,which greatly depends on the psychoacoustic parameters.However,the traditional psychoacoustic calculation method does not c...When designing and optimizing the hull of vehicles,their sound quality needs to be considered,which greatly depends on the psychoacoustic parameters.However,the traditional psychoacoustic calculation method does not consider the influence of the real human ear anatomic structure,even the loudness which is most related to the auditory periphery.In order to introduce the real physiological structure of the human ear into the evaluation of vehicle sound quality,this paper first carried out the vehicle internal noise test to obtain the experimental samples.Then,the physiological loudness was predicted based on an established human ear physiological model,and the noise evaluation vector was constructed by combining the remaining four psychoacoustic parameters.Finally,the evaluation vector was fitted into the subjective evaluation results of vehicle interior noise by a deep neural network.The results show that our proposed method can estimate the human subjective perception of vehicle interior noise well.展开更多
This study explores the application of Bayesian econometrics in policy evaluation through theoretical analysis. The research first reviews the theoretical foundations of Bayesian methods, including the concepts of Bay...This study explores the application of Bayesian econometrics in policy evaluation through theoretical analysis. The research first reviews the theoretical foundations of Bayesian methods, including the concepts of Bayesian inference, prior distributions, and posterior distributions. Through systematic analysis, the study constructs a theoretical framework for applying Bayesian methods in policy evaluation. The research finds that Bayesian methods have multiple theoretical advantages in policy evaluation: Based on parameter uncertainty theory, Bayesian methods can better handle uncertainty in model parameters and provide more comprehensive estimates of policy effects;from the perspective of model selection theory, Bayesian model averaging can reduce model selection bias and enhance the robustness of evaluation results;according to causal inference theory, Bayesian causal inference methods provide new approaches for evaluating policy causal effects. The study also points out the complexities of applying Bayesian methods in policy evaluation, such as the selection of prior information and computational complexity. To address these complexities, the study proposes hybrid methods combining frequentist approaches and suggestions for developing computationally efficient algorithms. The research also discusses theoretical comparisons between Bayesian methods and other policy evaluation techniques, providing directions for future research.展开更多
The threshold stress, σc, for sulfide stress corrosion cracking (SCC) of seven pipeline steels and five other steels, the critical stress, Sc, for seven pipeline steels and two drill rod steels with various strengths...The threshold stress, σc, for sulfide stress corrosion cracking (SCC) of seven pipeline steels and five other steels, the critical stress, Sc, for seven pipeline steels and two drill rod steels with various strengths and the susceptibility to SCC, IRA or σf(SCC)/σf, for four pipeline steels, two drill rod steels and five other steels were measured. The results showed that there are no definite relationships among σc, Sc and IRA or σf(SCC)/σf.The threshold stress for hydrogen induced cracking (HlC) during charging with loading in the H2S04 solution, σc(H), decreased linearly with logarithm of the concentration of diffusible hydrogen c0, i.e., σc(H)=A-B Inco for four pipeline steels. σc(H) obtained with a special cathodic current ic, which was corresponding to the diffusible hydrogen concentration during immersing in the H2S solution, were consistent with /c for sulfide SCC for four pipeline steels. Therefore, σc for sulfide SCC can be measured using dynamically charging in the H2SO4 solution with the special cathodic current ic.展开更多
基金supported by National Natural Science Foundation of China(51974166).
文摘Recently,azobenzene-4,4'-dicarboxylic acid(ADCA)has been produced gradually for use as an organic synthesis or pharmaceutical intermediate due to its eminent performance.With large quantities put into application in the future,the thermal stability of this substance during storage,transportation,and use will become quite important.Thus,in this work,the thermal decomposition behavior,thermal decomposition kinetics,and thermal hazard of ADCA were investigated.Experiments were conducted by using a SENSYS evo DSC device.A combination of differential iso-conversion method,compensation parameter method,and nonlinear fitting evaluation were also used to analyze thermal kinetics and mechanism of ADCA decomposition.The results show that when conversion rate α increases,the activation energies of ADCA's first and main decomposition peaks fall.The amount of heat released during decomposition varies between 182.46 and 231.16 J·g^(-1).The proposed kinetic equation is based on the Avrami-Erofeev model,which is consistent with the decomposition progress.Applying the Frank-Kamenetskii model,a calculated self-accelerating decomposition temperature of 287.0℃is obtained.
基金Shanxi Province Science and Technology Research Project(No.20140321008-03)
文摘The paper analyzes the factors influencing machine tool selection. By using fuzzy mathematics theory, we establish a theorietical model for optimal machine tool selection considering geometric features, clamping size, machining range, machining precision and surface roughness. By means of fuzzy comprehensive evaluation method, the membership degree of machine tool selection and the largest comprehensive evaluation index are determined. Then the reasonably automatic selection of machine tool is realized in the generative computer aided process planning （CAPP） system. Finally, the finite element model based on ABAQUS is established and the cutting process of machine tool is simulated. According to the theoretical and empirical cutting parameters and the curve of surface residual stress, the optimal cutting parameters can be determined.
基金Supported by National Natural Science Foundation of China(Grant No.51875412)Top Discipline Plan of Shanghai Universities-ClassⅠ。
文摘Carbon fiber reinforced polymer(CFRP)are widely used in various fields because of their high strength,good toughness,and low density.However,owing to their unique forming process,some complex structures such as holes and grooves cannot be formed directly.Therefore,traditional machining procedures are also required.The drilling process is one of the most common machining methods for CFRP holes,but owing to the complex structure and difficulty in processing CFRP,the quality of the drilling process is often challenging to guarantee.Moreover,the hole-forming defects also have complex forms and lack uniform evaluation indexes.This study summarizes the common orifice defects in the process of CFRP drilling,establishes a comprehensive evaluation method of orifice defects by introducing the relevant theory of the fuzzy complementary judgment matrix,and experimentally verifies the accuracy and reliability of this method.Then,based on the experimental results,a non-linear cutting parameter optimization model is established,which effectively suppresses the orifice defects to ensure the accuracy of the hole size,roundness,and hole wall roughness.The hole-forming quality is subsequently improved.The hole quality evaluation method proposed in this study reduced the dimension of the evaluation index to ensure relevance and effectiveness and improved the convenience of quality inspection and parameter optimization in actual production.
基金supported by the National Science and Technology Major Project,China,the China Scholarship Council(No.202306290109)National Natural Science Foundation of China(Nos.52472456 and 52361165620)。
文摘This paper studies the coupling mechanism between the nonlinear stiffness and damping coefficients of Active Elastic Support/Dry Friction Damper(AESDFD)and rotor system.First,parameters for evaluating the vibration reduction characteristics are proposed to facilitate the design of the AESDFD.To achieve this,the nonlinear friction force is initially represented as equivalent stiffness and damping coefficients,based on the ball-plate friction model.Second,three evaluation parameters—optimal slipping displacement,loss factor,and controllability—are proposed to reveal the vibration reduction characteristics of the AESDFD,alongside determining the optimal normal force.Subsequently,the finite element method,in conjunction with the ball-plate friction model,is introduced to formulate the governing equation of a low-pressure rotor system equipped with AESDFDs.The steady-state responses of the AESDFDs-rotor system are solved using the harmonic balance method combined with an efficient iteration method.Finally,the solutions are validated on the AESDFDs-rotor system both numerically and experimentally.The results indicate that controllability effectively assesses the vibration reduction performance of the AESDFD and is relatively insensitive to variations in low normal force.Away from the critical speed,the AESDFD suppresses vibration by altering the resonance position of the rotor system through its stiffness coefficient.Near the critical speed,vibration reduction is achieved primarily through energy dissipation by the damping coefficient.If the loss factor is less than one,the stiffness coefficient can diminish the vibration reduction effect of the damping coefficient.Notably,the optimal normal force of the AESDFD achieves optimal vibration reduction effect.This study reveals that changes in rotor system unbalance do not affect the vibration reduction characteristics of the AESDFD,with the same upper limit to the vibration reduction effect of the AESDFD.
基金Under the auspices of National Natural Science Foundation of China (No. 40830535)Knowledge Innovation Pro-gram of Chinese Academy of Sciences (No.KSCX2-YW-N-46-06)
文摘In order to improve the effectiveness of Fuzzy Synthetic Evaluation (FSE) models, a Parameter Correlation Analysis (PCA) was introduced into the FSE and a case study was carried out in the Naoli River in the Sanjiang Plain, Northeast China. The basic principle of the PCA is that the pairs of parameters which are highly correlated and linear with each other would contribute the same information to an assessment and one of them should be eliminated. The method of the PCA is that a correlation relationship among candidate parameters is examined before the FSE. If there is an apparent nonlinear or curvilinear relationship between two parameters, then both will be retained; if the correlation is significant (p<0.01), and the scatter plot suggests a linear relationship, then one of them will be deleted. However, which one will be deleted? For solving this problem, a sensitivity test was conducted and the higher sensitivity parameters remained. The results indicate that the original data should be preprocessed through the PCA for redundancy and variability. The study shows that introducing the PCA into the FSE can simplify the FSE calculation process greatly, while the results have not been changed much.
基金supported by the National Natural Science Foundation of China(Nos.61773388,61751304,61833016,and 61702142)the Shaanxi Outstanding Youth Science Foundation(No.2020JC-34)the Key Research and Development Plan of Hainan(No.ZDYF2019007)。
文摘The composition of the modern aerospace system becomes more and more complex.The performance degradation of any device in the system may cause it difficult for the whole system to keep normal working states.Therefore,it is essential to evaluate the performance of complex aerospace systems.In this paper,the performance evaluation of complex aerospace systems is regarded as a Multi-Attribute Decision Analysis(MADA)problem.Based on the structure and working principle of the system,a new Evidential Reasoning(ER)based approach with uncertain parameters is proposed to construct a nonlinear optimization model to evaluate the system performance.In the model,the interval form is used to express the uncertainty,such as error in testing data and inaccuracy in expert knowledge.In order to analyze the subsystems that have a great impact on the performance of the system,the sensitivity analysis of the evaluation result is carried out,and the corresponding maintenance strategy is proposed.For a type of Inertial Measurement Unit(IMU)used in a rocket,the proposed method is employed to evaluate its performance.Then,the parameter sensitivity of the evaluation result is analyzed,and the main factors affecting the performance of IMU are obtained.Finally,the comparative study shows the effectiveness of the proposed method.
文摘The statistical probability and their variation regularity of the measurable characteristic parameters in the CO 2 arc welding droplet short circuiting transfer process have been studied. The statistical analysis shows that the sensitivity of each characteristic parameter with regard to the variation of the short circuiting transfer process is different. The sensitivity of 4 kinds among these characteristic parameters is more intense than that of the short circuiting transfer frequency. In order to take account of the synthetic influence of these characteristic parameters, by means of the characteristic parameters synthetic value, a quantitative evaluation function is built up to describe and evaluate the short circuiting transfer process of CO 2 arc welding in real time. The testing shows that the evaluation function can give a suitable synthetic valuation for the short circuiting transfer process with a variety of welding variables.
基金The research work is supported by the National Science Foundation of China(Nos.11572058,11772028,11872131 and U1864208).
文摘Delamination represents one of the most severe failure modes in composite laminates,especially when they are subjected to uniaxial compression loads.The evaluation of the delamination damage has always been an essential issue of composite laminates for durability and damage tolerance in engineering practice.Focusing on the most typical and representative elliptical delamination issue,an analytical model simultaneously considering the conservative buckling process and non-conservative delamination propagation process is implemented.Various computational cases considering different delamination depths,directions,aspect ratios,and areas are established,and the predicted results based on the analytical model are carefully compared.Effects of these geometrical delamination parameters on the buckling,delamination propagation,and failure behaviors of composite laminates are thoroughly analyzed,and innovative evaluation principles of the delamination damage have been concluded.It is found that the delamination area is the key factor that truly affecting the failure behaviors of delaminated composites,and the local/global buckling and failure loads show clear linearity with the delamination area,whilst the delamination depth and direction only have slight effects.
基金National Natural Science Foundation of China, No.41001080 No.41271184+1 种基金 No.40971075 No.40771054
文摘Research has shown that there has been a significant change in the quantitative relationship between urbanization and economic development over the past 50 years. As a result of this change, the Chenery model is no longer capable of performing a comparative analysis of these parameters. We carried out a regression analysis of the normal form of the relation between urbanization and economic development on the basis of the Chenery model. We used empirical data from 149 countries and regions from 1990 to 2009 and adopted the double logarithmic model, introducing a time series variable for urbanization. From 1990 to 2009, with a per capita gross national income remaining between USD 1000 and 10,000, the urbanization rate changed from 17.78 to 60.36% and the relational matching data changed accordingly, although the upper limit of the rate of urbanization remained at about 75%. Urbanization in countries with a smaller population size was more affected by economic development than urbanization in countries with large and medium sized populations.
文摘The evaluation problem with three-parameter interval grey number (T-PIGN) widely exists in real world. To select effective evaluation indicators of the problem, this paper puts forward evaluation index system selection principle of T-PIGN based on distance entropy model, and gives out evaluation index system selection judgment criterion of T-PIGN. Furthermore, for the redundancy of evaluation index system with T-PIGN, a selection method of evaluation index system with T-PIGN is proposed. Finally, the applicability of the proposed method is verified by concrete examples.
文摘An efficient procedure is used for explicit description and evaluation of uncertainty of earthquake parameters in the uniform catalog of earthquakes in Iran and neighboring regions.An inadequate number of local and regional seismographic stations,poor station distribution,and Inadequacy of velocity models have resulted in conspicuous uncertainty in different parameters of recorded events.In a comprehensive seismic hazard analysis such uncertainties should be considered.Uncertainty of magnitude and location of events are evaluated for three different time periods,namely,historical,early instrumental,and modern instrumental time periods,for which existing seismological information differ widely in quantity,quality,and type.It is concluded that an uncertainty of 0.2-0.3 units of magnitude and 10-15 km in epicenter determinations should be considered in the most favorable conditions.None of the hypocenters of earthquakes in Iran can be considered as reliable,unless supported by other information such as
文摘A Z-parameter method is used to evaluate the damage process of HK40 austenitic steel. By using Z-parameter based on the Larson-Miller method, the nonlinear master curve of the log stress vs Larson-Miller parameter P can be expressed as： P=27.74-3.41gσ-0.032σ, and a family of curves parallel to the master curve can be written as： P=（27.74-Z）-3.41gσ-0.032σ, where Z represents the magnitude of the deviation from the master curve. According to the creep rupture data both from different segments of a serviced tube and from the same segment locations with different service time, the value of parameter Z has close relationship with the deterioration of creep rupture properties. The damage state of the samples is evaluated by monitoring the changes in natural frequency f and Young＇s modulus E, and the relationships between Z and the damage parameters are discussed.
基金the National Natural Science Foundation of China （Grant No. 30270759） the Science and Technology Department of Zhejiang Province （Grant No. 2005C32001）.
文摘Eleven evaluating parameters for rice core collection were assessed based on genotypic values and molecular marke＇ information. Monte Carlo simulation combined with mixed linear model was used to eliminate the interference from environment in order to draw more reliable results. The coincidence rate of range （CR） was the optimal parameter. Mean Simpson index （MD）, mean Shannon-Weaver index of genetic diversity （M1） and mean polymorphism information content （MPIC） were important evaluating parameters. The variable rate of coefficient of variation （VR） could act as an important reference parameter for evaluating the variation degree of core collection. Percentage of polymorphic loci （p） could be used as a determination parameter for the size of core collection. Mean difference percentage （MD） was a determination parameter for the reliability judgment of core collection. The effective evaluating parameters for core collection selected in the research could be used as criteria for sampling percentage in different plant germplasm populations.
基金the financial support of the Tsinghua University Foundation (Grant No. Jc~2OOOO57), and the Visiting Sch
文摘A novel parameter is suggested for evaluating the fatigue crack growth rate in carbon steels. Fatigue crack propagation tests of an annealed 0.42% carbon steel were carried out under different conditions to investigate the relationship between this dominating parameter and the crack opening displacement (COD). A new equation of fatigue crack growth rate is formulated in terms of the suggested parameter. The physical meanings of the material parameters in this equation are explored experimentally. Considering the relation of crack growth and deformation properties, a simple and applicable method is proposed to evaluate the fatigue crack growth rate. It is also observed that the material parameters in the fatigue crack growth rate equation of carbon steels are related linearly to the material strength. The results are in a good agreement with experimental results.
基金funding support from National Natural Science Foundation of China(52074322)Beijing Natural Science Foundation(3204052)+1 种基金Science Foundation of China University of Petroleum,Beijing(No.2462018YJRC032)National Major Project of China(2017ZX05030002-005)。
文摘Parameter inversions in oil/gas reservoirs based on well test interpretations are of great significance in oil/gas industry.Automatic well test interpretations based on artificial intelligence are the most promising to solve the problem of non-unique solution.In this work,a new deep reinforcement learning(DRL)based approach is proposed for automatic curve matching for well test interpretation,by using the double deep Q-network(DDQN).The DDQN algorithms are applied to train agents for automatic parameter tuning in three conventional well-testing models.In addition,to alleviate the dimensional disaster problem of parameter space,an asynchronous parameter adjustment strategy is used to train the agent.Finally,field applications are carried out by using the new DRL approaches.Results show that step number required for the DDQN to complete the curve matching is the least among,when comparing the naive deep Q-network(naive DQN)and deep Q-network(DQN).We also show that DDQN can improve the robustness of curve matching in comparison with supervised machine learning algorithms.Using DDQN algorithm to perform 100 curve matching tests on three traditional well test models,the results show that the mean relative error of the parameters is 7.58%for the homogeneous model,10.66%for the radial composite model,and 12.79%for the dual porosity model.In the actual field application,it is found that a good curve fitting can be obtained with only 30 steps of parameter adjustment.
基金supported by the Strategic Cooperation Technology Projects of CNPC and CUPB (ZLZX2020-03)National Key Research and Development Program (2019YFA0708301)+1 种基金National Key Research and Development Program (2023YFF0714102)Science and Technology Innovation Fund of CNPC (2021DQ02-0403).
文摘relationships between logging data and reservoir parameters.We compare our method’s performances using two datasets and evaluate the influences of multi-task learning,model structure,transfer learning,and petrophysics informed machine learning(PIML).Our experiments demonstrate that PIML significantly enhances the performance of formation evaluation,and the structure of residual neural network is optimal for incorporating petrophysical constraints.Moreover,PIML is less sensitive to noise.These findings indicate that it is crucial to integrate data-driven machine learning with petrophysical mechanism for the application of artificial intelligence in oil and gas exploration.
基金Natural Science Foundation of China(NSFC),Grant No.52404016(Lijuan Huang)Natural Science Foundation of Hubei Province,Grant No.2024AFB322(Lijuan Huang)Open Fund of Hubei Key Laboratory of Oil and Gas Drilling and Production Engineering(Yangtze University),Grant No.YQZC202405(Lijuan Huang).
文摘A comprehensive method to evaluate the factors affecting the production capacity of horizontal wells in Carboniferous volcanic rocks after fracturing is investigated.A systematic approach combining gray correlation analysis,hierarchical analysis and fuzzy evaluation is proposed.In particular,first the incidence of reservoir properties and fracturing parameters on production capacity is assessed.These parameters include reservoir base geological parameters(porosity,permeability,oil saturation,waterproof height)as well as engineering parameters(fracture halflength,fracture height,fracture conductivity,fracture distance).Afterwards,a two-by-two comparison judgment matrix of sensitive parameters is constructed by means of hierarchical analysis,and the weighting coefficients of the factors are determined,where oil saturation,fracture conductivity and fracture half-length are weighted higher.Finally,the horizontal wells in the target block are categorized in terms of production capacity based on the fuzzy evaluation method,and split accordingly into high-producing,relatively high-producing,medium-producing and low-producing wells.Such a categorization is intended to provide parametric guidance for reservoir fracturing and modification.
基金supported by the National Natural Science Foundation of China(Nos.52275296,52172371,and 52274162)the Top-Notch Academic Programs Project of Jiangsu Higher Education Institutions,the Priority Academic Program Development of Jiangsu Higher Education Institutions,and Jiangsu Provincial Postgraduate Practice Innovation Plan(No.SJCX23_1283).
文摘When designing and optimizing the hull of vehicles,their sound quality needs to be considered,which greatly depends on the psychoacoustic parameters.However,the traditional psychoacoustic calculation method does not consider the influence of the real human ear anatomic structure,even the loudness which is most related to the auditory periphery.In order to introduce the real physiological structure of the human ear into the evaluation of vehicle sound quality,this paper first carried out the vehicle internal noise test to obtain the experimental samples.Then,the physiological loudness was predicted based on an established human ear physiological model,and the noise evaluation vector was constructed by combining the remaining four psychoacoustic parameters.Finally,the evaluation vector was fitted into the subjective evaluation results of vehicle interior noise by a deep neural network.The results show that our proposed method can estimate the human subjective perception of vehicle interior noise well.
文摘This study explores the application of Bayesian econometrics in policy evaluation through theoretical analysis. The research first reviews the theoretical foundations of Bayesian methods, including the concepts of Bayesian inference, prior distributions, and posterior distributions. Through systematic analysis, the study constructs a theoretical framework for applying Bayesian methods in policy evaluation. The research finds that Bayesian methods have multiple theoretical advantages in policy evaluation: Based on parameter uncertainty theory, Bayesian methods can better handle uncertainty in model parameters and provide more comprehensive estimates of policy effects;from the perspective of model selection theory, Bayesian model averaging can reduce model selection bias and enhance the robustness of evaluation results;according to causal inference theory, Bayesian causal inference methods provide new approaches for evaluating policy causal effects. The study also points out the complexities of applying Bayesian methods in policy evaluation, such as the selection of prior information and computational complexity. To address these complexities, the study proposes hybrid methods combining frequentist approaches and suggestions for developing computationally efficient algorithms. The research also discusses theoretical comparisons between Bayesian methods and other policy evaluation techniques, providing directions for future research.
基金This project was supported by the NNSFC of China! (No.19891180, 59725104, 59895150) the Corporation of iron and Steel Baosha
文摘The threshold stress, σc, for sulfide stress corrosion cracking (SCC) of seven pipeline steels and five other steels, the critical stress, Sc, for seven pipeline steels and two drill rod steels with various strengths and the susceptibility to SCC, IRA or σf(SCC)/σf, for four pipeline steels, two drill rod steels and five other steels were measured. The results showed that there are no definite relationships among σc, Sc and IRA or σf(SCC)/σf.The threshold stress for hydrogen induced cracking (HlC) during charging with loading in the H2S04 solution, σc(H), decreased linearly with logarithm of the concentration of diffusible hydrogen c0, i.e., σc(H)=A-B Inco for four pipeline steels. σc(H) obtained with a special cathodic current ic, which was corresponding to the diffusible hydrogen concentration during immersing in the H2S solution, were consistent with /c for sulfide SCC for four pipeline steels. Therefore, σc for sulfide SCC can be measured using dynamically charging in the H2SO4 solution with the special cathodic current ic.
