The undrained mechanical behavior of unsaturated completely weathered granite(CWG)is highly susceptible to alterations in the hydraulic environment,particularly under uniaxial loading conditions,due to the unique natu...The undrained mechanical behavior of unsaturated completely weathered granite(CWG)is highly susceptible to alterations in the hydraulic environment,particularly under uniaxial loading conditions,due to the unique nature of this soil type.In this study,a series of unconfined compression tests were carried out on unsaturated CWG soil in an underground engineering site,and the effects of varying the environmental variables on the main undrained mechanical properties were analyzed.Based on the experimental results,a novel constitutive model was then established using the damage mechanics theory and the undetermined coefficient method.The results demonstrate that the curves of remolded CWG specimens with different moisture contents and dry densities exhibited diverse characteristics,including brittleness,significant softening,and ductility.As a typical indicator,the unconfined compression strength of soil specimens initially increased with an increase in moisture content and then decreased.Meanwhile,an optimal moisture content of approximately 10.5%could be observed,while a critical moisture content value of 13.0%was identified,beyond which the strength of the specimen decreases sharply.Moreover,the deformation and fracture of CWG specimens were predominantly caused by shear failure,and the ultimate failure modes were primarily influenced by moisture content rather than dry density.Furthermore,by comparing several similar models and the experimental data,the proposed model could accurately replicate the undrained mechanical characteristics of unsaturated CWG soil,and quantitatively describe the key mechanical indexes.These findings offer a valuable reference point for understanding the underlying mechanisms,anticipating potential risks,and implementing effective control measures in similar underground engineering projects.展开更多
One of the main objectives of artificial intelligence lies in the simulation of the behavior of living organisms;emotions are a fundamental part of life, and they cannot be left aside when simulating behavior. In this...One of the main objectives of artificial intelligence lies in the simulation of the behavior of living organisms;emotions are a fundamental part of life, and they cannot be left aside when simulating behavior. In this research, software is developed that simulates the behavior of birds with different characteristics. The latter interacts by considering different stimuli from the environment (external), and the internal state of the subject (objectives). To achieve this, a model of birds in the role of prey and predators is developed that focuses on the study of the interaction between these organisms that exhibit specific behaviors in their environment. This project is a seminal work that aims to represent the emotions of birds, and the latter caused by stimuli from a dynamic environment.展开更多
Background:Obesity remains a major global health challenge,closely linked to individuals'health beliefs and lifestyle behaviors.Descriptive and relational research methods were used to ascertain the correlation be...Background:Obesity remains a major global health challenge,closely linked to individuals'health beliefs and lifestyle behaviors.Descriptive and relational research methods were used to ascertain the correlation between health beliefs and healthy lifestyle behaviors in obese individuals based on the Health Belief Model.Methods:The population of the research are obese individuals who are treated in the internal medicine clinic in a state hospital in Diyarbakır and applied to a dietitian.Based on power analysis,the study’s sample consisted of 192 obese people.The health belief model scale in obese individuals(HBMSO),the Healthy Lifestyle Behaviors Scale-II(HLBS-II),and the Personal Information Form were used to gather the data.The data was evaluated using the following methods:mean,standard deviation,linear regression analysis,Mann-Whitney U test,Kruskal-Wallis test,Shapiro Wilk and Kolmogorov Smirnov tests,post-hoc Dunn-Benferronni tests,Pearson and Spearman correlation,and others.Results:It was determined that 26.0%of obese individuals were in the 46–55 age range,63.5%were female,64.6%were married,60.4%had a BMI in the range of 30–34.9 kg/m^(2),and 42.7%partially exercised.All sub-dimensions and HBMSO sub-dimensions had statistically significant correlation with the HLBS-II total score.The linear regression analysis results used to identify the predictors of the HLBS-II total score showed that the increase in the level of education and the HBMSO“Importance of Health”sub-dimension score increased the HLBS-II total score,while not exercising and an increase in the HBMSO“Obstacle Perception”sub-dimension score decreased the HLBS-II total score.Conclusion:Individuals’health attitudes have a major impact on leading a healthy lifestyle,which is consistent with the research results.展开更多
The effects of solid solution on the deformation behavior of binary Mg-xZn(x=0,1,2 wt%)alloys featuring a designated texture that enables extension twinning under tension parallel to the basal pole in most grains,were...The effects of solid solution on the deformation behavior of binary Mg-xZn(x=0,1,2 wt%)alloys featuring a designated texture that enables extension twinning under tension parallel to the basal pole in most grains,were investigated using in-situ neutron diffraction and the EVPSC-TDT model.Neutron diffraction was used to quantitatively track grain-level lattice strains and diffraction intensity changes(related to mechanical twinning)in differently oriented grains of each alloy during cyclic tensile/compressive loadings.These measurements were accurately captured by the model.The stress-strain curves of Mg-1 wt%Zn and Mg-2 wt%Zn alloys show as-expected solid solution strengthening from the addition of Zn compared to pure Mg.The macroscopic yielding and hardening behaviors are explained by alternating slip and twinning modes as calculated by the model.The solid solution's influence on individual deformation modes,including basal〈a〉slip,prismatic〈a〉slip,and extension twinning,was then quantitatively assessed in terms of activity,yielding behavior,and hardening response by combining neutron diffraction results with crystal plasticity predictions.The Mg-1 wt%Zn alloy displays distinct yielding and hardening behavior due to solid solution softening of prismatic〈a〉slip.Additionally,the dependence of extension twinning,in terms of the twinning volume fraction,on Zn content exhibits opposite trends under tensile and compressive loadings.展开更多
The popular constitutive models used in the field of hot forming of magnesium alloys can be divided into phenomenological models,machine learning models,and internal state variables(ISV)models based on physical mechan...The popular constitutive models used in the field of hot forming of magnesium alloys can be divided into phenomenological models,machine learning models,and internal state variables(ISV)models based on physical mechanisms.Currently,there is a lack of comparison and evaluation regarding the suitability of different types of models.In this study,Mg-Gd-Y-Zr alloy is taken as the research object.The hot deformation behavior of the alloy was studied systematically.Subsequently,Arrhenius model with strain compensation,artificial neural network(ANN)model,and ISV model involving dynamic recrystallization(DRX),dislocation density and grain size evolution were established.ANN model demonstrates a higher level of accuracy in fitting the original stress-strain curves compared to both ISV model and modified Arrhenius model,but ANN model is not suitable for predicting the experimental results outside of the initial database.ISV model considers the impact of microstructure evolution history on stress,making it highly effective in reflecting the mechanical responses under complex loading condition.The established ISV model is embedded in the ABAQUS software,which shows good ability in calculating the mechanical response,dimension,and microstructure evolution information of the component during hot forming.展开更多
Objective:To investigate the impact of health education nursing based on the Transtheoretical Model of Behavior Change on self-efficacy in osteoporosis patients with low bone mass.Methods:A total of 91 osteoporosis pa...Objective:To investigate the impact of health education nursing based on the Transtheoretical Model of Behavior Change on self-efficacy in osteoporosis patients with low bone mass.Methods:A total of 91 osteoporosis patients with low bone mass admitted to our hospital from June 2000 to the end of June 2023 were selected and randomly divided into an observation group and a control group using the envelope method,with 46 and 45 cases in each group,respectively.The control group received routine nursing care,while the observation group received health education nursing based on the Transtheoretical Model of Behavior Change.Bone mineral density(lumbar spine L1-L4,femoral neck),disease awareness(Osteoporosis Knowledge Test Questionnaire,OKT-Q),and self-efficacy(Adult Health Self-Management Skills Rating Scale,AHSMSRS)were compared between the two groups.Results:After the intervention,bone mineral density levels,disease awareness levels,and self-efficacy levels significantly increased in both groups,with the observation group showing greater improvements in all indicators compared to the control group(p<0.05).Conclusion:Interventions based on the Transtheoretical Model of Behavior Change effectively enhance patient self-efficacy and bone health by precisely matching behavioral stages,strengthening social support,and regulating neurobehavioral factors.展开更多
For studying the carbon thermal reduction rules of titanium in hot metal and providing a theoretical basis for the blast furnace（BF） hearth protection, the distribution behavior of titanium between low-titanium slag...For studying the carbon thermal reduction rules of titanium in hot metal and providing a theoretical basis for the blast furnace（BF） hearth protection, the distribution behavior of titanium between low-titanium slag system of CaO-SiO2-MgO-Al2O3-TiO2 and hot metal was studied using analytical reagents in a temperature range from 1350 °C to 1600 °C. Through high temperature melting, rapid quenching, chemical analysis and thermodynamic model calculating, the results showed that the increase of reaction temperature, which improved the titanium distribution L（Ti） and lowered the system activity coefficient γsys, leads to the rise of equilibrium constant. Combined with Wagner and congregated electron phase models, the data obtained in distribution experiments were used to fit out the Gibbs free energy formula of titanium carbothermic reduction. Finally, the relations between the contents of Si and Ti in hot metal and the titanium load to reach the minimum w（Ti） for the formation of Ti C were given.展开更多
A wavelet collocation method with nonlinear auto companding is proposed for behavioral modeling of switched current circuits.The companding function is automatically constructed according to the initial error distri...A wavelet collocation method with nonlinear auto companding is proposed for behavioral modeling of switched current circuits.The companding function is automatically constructed according to the initial error distribution obtained through approximating the input output function of the SI circuit by conventional wavelet collocation method.In practical applications,the proposed method is a general purpose approach,by which both the small signal effect and the large signal effect are modeled in a unified formulation to ease the process of modeling and simulation.Compared with the published modeling approaches,the proposed nonlinear auto companding method works more efficiently not only in controlling the error distribution but also in reducing the modeling errors.To demonstrate the promising features of the proposed method,several SI circuits are employed as examples to be modeled and simulated.展开更多
A novel behavioral model using three-layer time-delay feed-forward neural networks （TDFFNN）is adopted to model radio frequency （RF）power amplifiers exhibiting memory nonlinearities. In order to extract the paramet...A novel behavioral model using three-layer time-delay feed-forward neural networks （TDFFNN）is adopted to model radio frequency （RF）power amplifiers exhibiting memory nonlinearities. In order to extract the parameters, the back- propagation algorithm is applied to train the proposed neural networks. The proposed model is verified by the typical odd- order-only memory polynomial model in simulation, and the performance is compared with different numbers of taped delay lines（TDLs） and perceptrons of the hidden layer. For validating the TDFFNN model by experiments, a digital test bench is set up to collect input and output data of power amplifiers at a 60 × 10^6 sample/s sampling rate. The 3.75 MHz 16-QAM signal generated in the vector signal generator（VSG） is chosen as the input signal, when measuring the dynamic AM/AM and AM/PM characteristics of power amplifiers. By comparisons and analyses, the presented model provides a good performance in convergence, accuracy and efficiency, which is approved by simulation results and experimental results in the time domain and frequency domain.展开更多
This paper discusses some issues on human reliability model of time dependent human behavior. Some results of the crew reliability experiment on Tsinghua training simulator in China are given, Meanwhile, a case of ca...This paper discusses some issues on human reliability model of time dependent human behavior. Some results of the crew reliability experiment on Tsinghua training simulator in China are given, Meanwhile, a case of calculation for human error probability during anticipated transient without scram (ATWS) based on the data drew from the recent experiment is offered.展开更多
A computer model has been developed to simulate the distribution behaviors of Ni, Co. Sn. Ph,Zn, As, Sb, Bi, An and Ag in copper smelting process. The model assumes that the copper smelting furnaceis in thermodynamic ...A computer model has been developed to simulate the distribution behaviors of Ni, Co. Sn. Ph,Zn, As, Sb, Bi, An and Ag in copper smelting process. The model assumes that the copper smelting furnaceis in thermodynamic equilibrium. As many as 21 elements (Cu. S, Fe. Ni, Co. Sn, As, Sb. Bi, Ph. Zn.An. Ag. O, N, C, H, Ca, Mg, Al, and St) and 73 compounds are considered. This model accounts forphysical entrainment in the melts. The predictions by the present computer model are compared with theknown commercial data from Guixi Smelter in China, Home Smelter in Canada and Naoshima Smelter inJapan. The agreements between the computer predictions and the commercial data are excellent, so that thepresent computer model can be used to monitor and optimize the actual industrial operations of copper smelting. It is applicable to simulation of almost all copper pyrometallurgical processes.展开更多
Dynamic modeling and numerical simulation of hydrate slurry flow behavior are of great importance to offshore hydrate management.For this purpose, a dynamic model of hydrate agglomeration was proposed in this paper.Ba...Dynamic modeling and numerical simulation of hydrate slurry flow behavior are of great importance to offshore hydrate management.For this purpose, a dynamic model of hydrate agglomeration was proposed in this paper.Based on population balance equation, the frame of the dynamic model was established first, which took both hydrate agglomeration and hydrate breakage into consideration.Then, the calculating methods of four key parameters involved in the dynamic model were given according to hydrate agglomeration dynamics.The four key parameters are collision frequency, agglomeration efficiency, breakage frequency and the size distribution of sub particles resulting from particle breakage.After the whole dynamic model was built, it was combined with several traditional solid–liquid flow models and then together solved by the CFD software FLUENT 14.5.Finally, using this method, the influences of flow rate and hydrate volume fraction on hydrate particle size distribution, hydrate volume concentration distribution and pipeline pressure drop were simulated and analyzed.展开更多
The conventional Arrhenius-type model was adopted to identify the deformation characteristic of Ti6 A14 V(TC4) titanium alloy based on the stress-strain curves of isothermal compression test. A new flow stress model b...The conventional Arrhenius-type model was adopted to identify the deformation characteristic of Ti6 A14 V(TC4) titanium alloy based on the stress-strain curves of isothermal compression test. A new flow stress model based on Arrhenius equation was proposed for TC4,which is composed of peak flow stress(PFS) prediction and strain compensation. The predicted PFS is set as a reference to derive the flow stress model at any strain ranging from approximately 0 to 0.7. The predictability and efficiency among the proposed model, conventional model,and an existing physical-based model of TC4 were comparatively evaluated. It is found that the newly proposed model can simultaneously track the hardening and softening behaviors of TC4 through a single expression while the other existing models are only valid in the softening region.Besides, the wider application range and acceptable accuracy of the new model have been achieved by fewer material constants with much-simplified modeling procedure than the other models.展开更多
The dynamic tensile behaviors of a newly developed Ti-6 Al-2 Sn-2 Zr-3 Mo-1 Cr-2 Nb-Si alloy（referred as TC21 in China） over a wide range of strain rates from quasi-static to dynamic regimes(0.001-1 200 s-1) at diff...The dynamic tensile behaviors of a newly developed Ti-6 Al-2 Sn-2 Zr-3 Mo-1 Cr-2 Nb-Si alloy（referred as TC21 in China） over a wide range of strain rates from quasi-static to dynamic regimes(0.001-1 200 s-1) at different temperatures were experimentally investigated. A split Hopkinson tension bar apparatus and a static material testing system were utilized to study the stress-strain responses under uniaxial tension loading condition. The experimental results indicate that the tensile behavior of TC21 titanium alloy is dependent on the strain rate and temperature. The values of initial yield stress increase with increasing strain rate and decreasing temperature. The effects of strain rate and temperature on the initial yield behavior are estimated by introducing two sensitivity parameters. The phenomenological-based constitutive model, Johnson-Cook model, is suitably modified to describe the rate-temperature dependent constitutive behavior of TC21 titanium alloy. It is observed that the modified model is in good agreement with the experimental data subjected to the investigated range of strain rates and temperatures.展开更多
Experiments on rock joint behaviors have shown that joint surface roughness is mobilized under shearing,inducing dilation and resulting in nonlinear joint shear strength and shear stress vs.shear displacement behavior...Experiments on rock joint behaviors have shown that joint surface roughness is mobilized under shearing,inducing dilation and resulting in nonlinear joint shear strength and shear stress vs.shear displacement behaviors.The Barton-Bandis(B-B) joint model provides the most realistic prediction for the nonlinear shear behavior of rock joints.The B-B model accounts for asperity roughness and strength through the joint roughness coefficient(JRC) and joint wall compressive strength(JCS) parameters.Nevertheless,many computer codes for rock engineering analysis still use the constant shear strength parameters from the linear Mohr-Coulomb(M-C) model,which is only appropriate for smooth and non-dilatant joints.This limitation prevents fractured rock models from capturing the nonlinearity of joint shear behavior.To bridge the B-B and the M C models,this paper aims to provide a linearized implementation of the B-B model using a tangential technique to obtain the equivalent M-C parameters that can satisfy the nonlinear shear behavior of rock joints.These equivalent parameters,namely the equivalent peak cohesion,friction angle,and dilation angle,are then converted into their mobilized forms to account for the mobilization and degradation of JRC under shearing.The conversion is done by expressing JRC in the equivalent peak parameters as functions of joint shear displacement using proposed hyperbolic and logarithmic functions at the pre-and post-peak regions of shear displacement,respectively.Likewise,the pre-and post-peak joint shear stiffnesses are derived so that a complete shear stress-shear displacement relationship can be established.Verifications of the linearized implementation of the B-B model show that the shear stress-shear displacement curves,the dilation behavior,and the shear strength envelopes of rock joints are consistent with available experimental and numerical results.展开更多
The pressure-driven mold filling ability of aluminum alloy melt/semi-solid slurry is of great significance in pressure casting processes,and the rheological behavior of the alloy has a crucial effect on the mold filli...The pressure-driven mold filling ability of aluminum alloy melt/semi-solid slurry is of great significance in pressure casting processes,and the rheological behavior of the alloy has a crucial effect on the mold filling ability according to fluid dynamics.In this work,a pressure-driven mold filling model is first proposed based on the rheological behavior of the alloys.A356 alloy is employed as an example to clarify the rheological behavior of aluminum alloys,which obeys the power law model and is affected by temperature.The rheological behavior of the alloy in semi-solid state is modelled with the coupling of shear rate and temperature.The stop of mold filling attributes to the pressure loss which is caused by the viscosity during the flow of the melt/semi-solid slurry.Pressure loss caused by viscous flow and heat transfer between the alloy and the mold are calculated and coupled during the mold filling of the melt/semi-solid slurry.A pressure-driven mold filling model of aluminum alloy melt/semi-solid slurry is established based on steady-state rheological behavior.The model successfully predicts the filling length of melt/semi-solid slurry in pressure casting processes.Compared with the experimental results,the model can provide a quantitative approach to characterize the pressure-driven mold filling ability of aluminum alloy melt.The model is capable of describing the stop filling behavior of other aluminum alloys in pressure casting processes with corresponding rheological parameters and heat transfer coefficient.展开更多
CNC machining systems are inevitably confronted with frequent changes in energy behaviors because they are widely used to perform various machining tasks. It is a challenge to understand and analyze the flexible energ...CNC machining systems are inevitably confronted with frequent changes in energy behaviors because they are widely used to perform various machining tasks. It is a challenge to understand and analyze the flexible energy behaviors in CNC machining systems. A method to model flexible energy behaviors in CNC machining systems based on hierarchical objected-oriented Petri net(HOONet) is proposed. The structure of the HOONet is constructed of a high-level model and detail models. The former is used to model operational states for CNC machining systems, and the latter is used to analyze the component models for operational states. The machining parameters having great impacts on energy behaviors in CNC machining systems are declared with the data dictionary in HOONet models. A case study based on a CNC lathe is presented to demonstrate the proposed modeling method. The results show that it is effective for modeling flexible energy behaviors and providing a fine-grained description to quantitatively analyze the energy consumption of CNC machining systems.展开更多
The thermomechanical behavior of precipitation-hardened aluminum alloy AA7022-T6 was studied using isothermal compression at temperatures of 623−773 K and strain rates of 0.01−1 s^−1.The experimental results indicated...The thermomechanical behavior of precipitation-hardened aluminum alloy AA7022-T6 was studied using isothermal compression at temperatures of 623−773 K and strain rates of 0.01−1 s^−1.The experimental results indicated that dynamic recrystallization(DRX)is a predominant hot deformation mechanism,especially at elevated temperatures and low strain rates.The modified Johnson−Cook(J−C)and the strain compensated Arrhenius-type models were developed to predict the hot flow behavior under different deformation conditions.The correlation coefficients of modified J−C model and the strain compensated Arrhenius-type models were 0.9914 and 0.9972,respectively,their average relative errors(ARE)were 6.074%and 4.465%,respectively,and their root mean square errors(RMSE)were 10.611 and 1.665 MPa,respectively,indicating that the strain compensated Arrhenius-type model can predict the hot flow stress of AA7022-T6 aluminum alloy with an appropriate accuracy.展开更多
Magnesium alloys have shown great potential for their use in the medical device field, due to the promising biodegradability. However, it remains a challenge to characterize the degradation behavior of the Mg alloys i...Magnesium alloys have shown great potential for their use in the medical device field, due to the promising biodegradability. However, it remains a challenge to characterize the degradation behavior of the Mg alloys in a quantitative manner. As such, controlling the degradation rate of the Mg alloys as per our needs is still hard, which greatly limits the practical application of the Mg alloys as a degradable biomaterial.This paper discussed a numerical model developed based on the diffusion theory, which can capture the experimental degradation behavior of the Mg alloys precisely. The numerical model is then implemented into a finite element scheme, where the model is calibrated with the data from our previous studies on the corrosion of the as-cast Mg-1 Ca and the as-rolled Mg-3 Ge binary alloys. The degradation behavior of a pin implant is predicted using the calibrated model to demonstrate the model’s capability. A standard flow is provided in a practical framework for obtaining the degradation behavior of any biomedical Mg alloys. This methodology was further verified via the comparison with enormous available experimental results. Lastly, the material parameters defined in this model were provided as a new kind of material property.展开更多
基金Project(42202318)supported by the National Natural Science Foundation of ChinaProject(252300421199)supported by the Natural Science Foundation of Henan Province,ChinaProject(2024JJ6219)supported by the Hunan Provincial Natural Science Foundation of China。
文摘The undrained mechanical behavior of unsaturated completely weathered granite(CWG)is highly susceptible to alterations in the hydraulic environment,particularly under uniaxial loading conditions,due to the unique nature of this soil type.In this study,a series of unconfined compression tests were carried out on unsaturated CWG soil in an underground engineering site,and the effects of varying the environmental variables on the main undrained mechanical properties were analyzed.Based on the experimental results,a novel constitutive model was then established using the damage mechanics theory and the undetermined coefficient method.The results demonstrate that the curves of remolded CWG specimens with different moisture contents and dry densities exhibited diverse characteristics,including brittleness,significant softening,and ductility.As a typical indicator,the unconfined compression strength of soil specimens initially increased with an increase in moisture content and then decreased.Meanwhile,an optimal moisture content of approximately 10.5%could be observed,while a critical moisture content value of 13.0%was identified,beyond which the strength of the specimen decreases sharply.Moreover,the deformation and fracture of CWG specimens were predominantly caused by shear failure,and the ultimate failure modes were primarily influenced by moisture content rather than dry density.Furthermore,by comparing several similar models and the experimental data,the proposed model could accurately replicate the undrained mechanical characteristics of unsaturated CWG soil,and quantitatively describe the key mechanical indexes.These findings offer a valuable reference point for understanding the underlying mechanisms,anticipating potential risks,and implementing effective control measures in similar underground engineering projects.
文摘One of the main objectives of artificial intelligence lies in the simulation of the behavior of living organisms;emotions are a fundamental part of life, and they cannot be left aside when simulating behavior. In this research, software is developed that simulates the behavior of birds with different characteristics. The latter interacts by considering different stimuli from the environment (external), and the internal state of the subject (objectives). To achieve this, a model of birds in the role of prey and predators is developed that focuses on the study of the interaction between these organisms that exhibit specific behaviors in their environment. This project is a seminal work that aims to represent the emotions of birds, and the latter caused by stimuli from a dynamic environment.
文摘Background:Obesity remains a major global health challenge,closely linked to individuals'health beliefs and lifestyle behaviors.Descriptive and relational research methods were used to ascertain the correlation between health beliefs and healthy lifestyle behaviors in obese individuals based on the Health Belief Model.Methods:The population of the research are obese individuals who are treated in the internal medicine clinic in a state hospital in Diyarbakır and applied to a dietitian.Based on power analysis,the study’s sample consisted of 192 obese people.The health belief model scale in obese individuals(HBMSO),the Healthy Lifestyle Behaviors Scale-II(HLBS-II),and the Personal Information Form were used to gather the data.The data was evaluated using the following methods:mean,standard deviation,linear regression analysis,Mann-Whitney U test,Kruskal-Wallis test,Shapiro Wilk and Kolmogorov Smirnov tests,post-hoc Dunn-Benferronni tests,Pearson and Spearman correlation,and others.Results:It was determined that 26.0%of obese individuals were in the 46–55 age range,63.5%were female,64.6%were married,60.4%had a BMI in the range of 30–34.9 kg/m^(2),and 42.7%partially exercised.All sub-dimensions and HBMSO sub-dimensions had statistically significant correlation with the HLBS-II total score.The linear regression analysis results used to identify the predictors of the HLBS-II total score showed that the increase in the level of education and the HBMSO“Importance of Health”sub-dimension score increased the HLBS-II total score,while not exercising and an increase in the HBMSO“Obstacle Perception”sub-dimension score decreased the HLBS-II total score.Conclusion:Individuals’health attitudes have a major impact on leading a healthy lifestyle,which is consistent with the research results.
基金supported by the National Research Foundation grant funded by the Korean government(No,2023R1A2C2007190,RS-2024-00398068)partially funded by the Natural Science Foundation of Shandong Province,China(No.ZR2022QE206).
文摘The effects of solid solution on the deformation behavior of binary Mg-xZn(x=0,1,2 wt%)alloys featuring a designated texture that enables extension twinning under tension parallel to the basal pole in most grains,were investigated using in-situ neutron diffraction and the EVPSC-TDT model.Neutron diffraction was used to quantitatively track grain-level lattice strains and diffraction intensity changes(related to mechanical twinning)in differently oriented grains of each alloy during cyclic tensile/compressive loadings.These measurements were accurately captured by the model.The stress-strain curves of Mg-1 wt%Zn and Mg-2 wt%Zn alloys show as-expected solid solution strengthening from the addition of Zn compared to pure Mg.The macroscopic yielding and hardening behaviors are explained by alternating slip and twinning modes as calculated by the model.The solid solution's influence on individual deformation modes,including basal〈a〉slip,prismatic〈a〉slip,and extension twinning,was then quantitatively assessed in terms of activity,yielding behavior,and hardening response by combining neutron diffraction results with crystal plasticity predictions.The Mg-1 wt%Zn alloy displays distinct yielding and hardening behavior due to solid solution softening of prismatic〈a〉slip.Additionally,the dependence of extension twinning,in terms of the twinning volume fraction,on Zn content exhibits opposite trends under tensile and compressive loadings.
基金supported by the fund of the National Natural Science Foundation of China(52275322,51875127)。
文摘The popular constitutive models used in the field of hot forming of magnesium alloys can be divided into phenomenological models,machine learning models,and internal state variables(ISV)models based on physical mechanisms.Currently,there is a lack of comparison and evaluation regarding the suitability of different types of models.In this study,Mg-Gd-Y-Zr alloy is taken as the research object.The hot deformation behavior of the alloy was studied systematically.Subsequently,Arrhenius model with strain compensation,artificial neural network(ANN)model,and ISV model involving dynamic recrystallization(DRX),dislocation density and grain size evolution were established.ANN model demonstrates a higher level of accuracy in fitting the original stress-strain curves compared to both ISV model and modified Arrhenius model,but ANN model is not suitable for predicting the experimental results outside of the initial database.ISV model considers the impact of microstructure evolution history on stress,making it highly effective in reflecting the mechanical responses under complex loading condition.The established ISV model is embedded in the ABAQUS software,which shows good ability in calculating the mechanical response,dimension,and microstructure evolution information of the component during hot forming.
基金National Key Research and Development Program of China(Project No.:2020YFC2004900)。
文摘Objective:To investigate the impact of health education nursing based on the Transtheoretical Model of Behavior Change on self-efficacy in osteoporosis patients with low bone mass.Methods:A total of 91 osteoporosis patients with low bone mass admitted to our hospital from June 2000 to the end of June 2023 were selected and randomly divided into an observation group and a control group using the envelope method,with 46 and 45 cases in each group,respectively.The control group received routine nursing care,while the observation group received health education nursing based on the Transtheoretical Model of Behavior Change.Bone mineral density(lumbar spine L1-L4,femoral neck),disease awareness(Osteoporosis Knowledge Test Questionnaire,OKT-Q),and self-efficacy(Adult Health Self-Management Skills Rating Scale,AHSMSRS)were compared between the two groups.Results:After the intervention,bone mineral density levels,disease awareness levels,and self-efficacy levels significantly increased in both groups,with the observation group showing greater improvements in all indicators compared to the control group(p<0.05).Conclusion:Interventions based on the Transtheoretical Model of Behavior Change effectively enhance patient self-efficacy and bone health by precisely matching behavioral stages,strengthening social support,and regulating neurobehavioral factors.
基金Project(2012CB720401)supported by the National Basic Research Program of ChinaProject(2011BAC01B02)supported by the National Key Technology R&D Program of China
文摘For studying the carbon thermal reduction rules of titanium in hot metal and providing a theoretical basis for the blast furnace（BF） hearth protection, the distribution behavior of titanium between low-titanium slag system of CaO-SiO2-MgO-Al2O3-TiO2 and hot metal was studied using analytical reagents in a temperature range from 1350 °C to 1600 °C. Through high temperature melting, rapid quenching, chemical analysis and thermodynamic model calculating, the results showed that the increase of reaction temperature, which improved the titanium distribution L（Ti） and lowered the system activity coefficient γsys, leads to the rise of equilibrium constant. Combined with Wagner and congregated electron phase models, the data obtained in distribution experiments were used to fit out the Gibbs free energy formula of titanium carbothermic reduction. Finally, the relations between the contents of Si and Ti in hot metal and the titanium load to reach the minimum w（Ti） for the formation of Ti C were given.
文摘A wavelet collocation method with nonlinear auto companding is proposed for behavioral modeling of switched current circuits.The companding function is automatically constructed according to the initial error distribution obtained through approximating the input output function of the SI circuit by conventional wavelet collocation method.In practical applications,the proposed method is a general purpose approach,by which both the small signal effect and the large signal effect are modeled in a unified formulation to ease the process of modeling and simulation.Compared with the published modeling approaches,the proposed nonlinear auto companding method works more efficiently not only in controlling the error distribution but also in reducing the modeling errors.To demonstrate the promising features of the proposed method,several SI circuits are employed as examples to be modeled and simulated.
基金The National Natural Science Foundation of China(No.60621002)the National High Technology Research and Development Pro-gram of China(863 Program)(No.2007AA01Z2B4).
文摘A novel behavioral model using three-layer time-delay feed-forward neural networks （TDFFNN）is adopted to model radio frequency （RF）power amplifiers exhibiting memory nonlinearities. In order to extract the parameters, the back- propagation algorithm is applied to train the proposed neural networks. The proposed model is verified by the typical odd- order-only memory polynomial model in simulation, and the performance is compared with different numbers of taped delay lines（TDLs） and perceptrons of the hidden layer. For validating the TDFFNN model by experiments, a digital test bench is set up to collect input and output data of power amplifiers at a 60 × 10^6 sample/s sampling rate. The 3.75 MHz 16-QAM signal generated in the vector signal generator（VSG） is chosen as the input signal, when measuring the dynamic AM/AM and AM/PM characteristics of power amplifiers. By comparisons and analyses, the presented model provides a good performance in convergence, accuracy and efficiency, which is approved by simulation results and experimental results in the time domain and frequency domain.
文摘This paper discusses some issues on human reliability model of time dependent human behavior. Some results of the crew reliability experiment on Tsinghua training simulator in China are given, Meanwhile, a case of calculation for human error probability during anticipated transient without scram (ATWS) based on the data drew from the recent experiment is offered.
文摘A computer model has been developed to simulate the distribution behaviors of Ni, Co. Sn. Ph,Zn, As, Sb, Bi, An and Ag in copper smelting process. The model assumes that the copper smelting furnaceis in thermodynamic equilibrium. As many as 21 elements (Cu. S, Fe. Ni, Co. Sn, As, Sb. Bi, Ph. Zn.An. Ag. O, N, C, H, Ca, Mg, Al, and St) and 73 compounds are considered. This model accounts forphysical entrainment in the melts. The predictions by the present computer model are compared with theknown commercial data from Guixi Smelter in China, Home Smelter in Canada and Naoshima Smelter inJapan. The agreements between the computer predictions and the commercial data are excellent, so that thepresent computer model can be used to monitor and optimize the actual industrial operations of copper smelting. It is applicable to simulation of almost all copper pyrometallurgical processes.
基金Supported by Shandong Provincial Natural Science Foundation,China(ZR2017MEE057)the Fundamental Research Funds for the Central Universities(14CX02207A,17CX05006,17CX06017)the Graduate Innovation Project of China University of Petroleum(East China)(YCX2017062)
文摘Dynamic modeling and numerical simulation of hydrate slurry flow behavior are of great importance to offshore hydrate management.For this purpose, a dynamic model of hydrate agglomeration was proposed in this paper.Based on population balance equation, the frame of the dynamic model was established first, which took both hydrate agglomeration and hydrate breakage into consideration.Then, the calculating methods of four key parameters involved in the dynamic model were given according to hydrate agglomeration dynamics.The four key parameters are collision frequency, agglomeration efficiency, breakage frequency and the size distribution of sub particles resulting from particle breakage.After the whole dynamic model was built, it was combined with several traditional solid–liquid flow models and then together solved by the CFD software FLUENT 14.5.Finally, using this method, the influences of flow rate and hydrate volume fraction on hydrate particle size distribution, hydrate volume concentration distribution and pipeline pressure drop were simulated and analyzed.
基金financially supported by the National Natural Science Foundation of China (No. 51475295)
文摘The conventional Arrhenius-type model was adopted to identify the deformation characteristic of Ti6 A14 V(TC4) titanium alloy based on the stress-strain curves of isothermal compression test. A new flow stress model based on Arrhenius equation was proposed for TC4,which is composed of peak flow stress(PFS) prediction and strain compensation. The predicted PFS is set as a reference to derive the flow stress model at any strain ranging from approximately 0 to 0.7. The predictability and efficiency among the proposed model, conventional model,and an existing physical-based model of TC4 were comparatively evaluated. It is found that the newly proposed model can simultaneously track the hardening and softening behaviors of TC4 through a single expression while the other existing models are only valid in the softening region.Besides, the wider application range and acceptable accuracy of the new model have been achieved by fewer material constants with much-simplified modeling procedure than the other models.
基金Funded by the National Natural Science Foundation of China Academy of Engineering Physics and Jointly Set up “NSAF” Joint Fund(No.U1430119)
文摘The dynamic tensile behaviors of a newly developed Ti-6 Al-2 Sn-2 Zr-3 Mo-1 Cr-2 Nb-Si alloy（referred as TC21 in China） over a wide range of strain rates from quasi-static to dynamic regimes(0.001-1 200 s-1) at different temperatures were experimentally investigated. A split Hopkinson tension bar apparatus and a static material testing system were utilized to study the stress-strain responses under uniaxial tension loading condition. The experimental results indicate that the tensile behavior of TC21 titanium alloy is dependent on the strain rate and temperature. The values of initial yield stress increase with increasing strain rate and decreasing temperature. The effects of strain rate and temperature on the initial yield behavior are estimated by introducing two sensitivity parameters. The phenomenological-based constitutive model, Johnson-Cook model, is suitably modified to describe the rate-temperature dependent constitutive behavior of TC21 titanium alloy. It is observed that the modified model is in good agreement with the experimental data subjected to the investigated range of strain rates and temperatures.
基金support from the University Transportation Center for Underground Transportation Infrastructure at the Colorado School of Mines for partially funding this research under Grant No.69A3551747118 of the Fixing America's Surface Transportation Act(FAST Act) of U.S.DoT FY2016
文摘Experiments on rock joint behaviors have shown that joint surface roughness is mobilized under shearing,inducing dilation and resulting in nonlinear joint shear strength and shear stress vs.shear displacement behaviors.The Barton-Bandis(B-B) joint model provides the most realistic prediction for the nonlinear shear behavior of rock joints.The B-B model accounts for asperity roughness and strength through the joint roughness coefficient(JRC) and joint wall compressive strength(JCS) parameters.Nevertheless,many computer codes for rock engineering analysis still use the constant shear strength parameters from the linear Mohr-Coulomb(M-C) model,which is only appropriate for smooth and non-dilatant joints.This limitation prevents fractured rock models from capturing the nonlinearity of joint shear behavior.To bridge the B-B and the M C models,this paper aims to provide a linearized implementation of the B-B model using a tangential technique to obtain the equivalent M-C parameters that can satisfy the nonlinear shear behavior of rock joints.These equivalent parameters,namely the equivalent peak cohesion,friction angle,and dilation angle,are then converted into their mobilized forms to account for the mobilization and degradation of JRC under shearing.The conversion is done by expressing JRC in the equivalent peak parameters as functions of joint shear displacement using proposed hyperbolic and logarithmic functions at the pre-and post-peak regions of shear displacement,respectively.Likewise,the pre-and post-peak joint shear stiffnesses are derived so that a complete shear stress-shear displacement relationship can be established.Verifications of the linearized implementation of the B-B model show that the shear stress-shear displacement curves,the dilation behavior,and the shear strength envelopes of rock joints are consistent with available experimental and numerical results.
基金supported financially by the National Key Research Project(No.2016YFB0300901).
文摘The pressure-driven mold filling ability of aluminum alloy melt/semi-solid slurry is of great significance in pressure casting processes,and the rheological behavior of the alloy has a crucial effect on the mold filling ability according to fluid dynamics.In this work,a pressure-driven mold filling model is first proposed based on the rheological behavior of the alloys.A356 alloy is employed as an example to clarify the rheological behavior of aluminum alloys,which obeys the power law model and is affected by temperature.The rheological behavior of the alloy in semi-solid state is modelled with the coupling of shear rate and temperature.The stop of mold filling attributes to the pressure loss which is caused by the viscosity during the flow of the melt/semi-solid slurry.Pressure loss caused by viscous flow and heat transfer between the alloy and the mold are calculated and coupled during the mold filling of the melt/semi-solid slurry.A pressure-driven mold filling model of aluminum alloy melt/semi-solid slurry is established based on steady-state rheological behavior.The model successfully predicts the filling length of melt/semi-solid slurry in pressure casting processes.Compared with the experimental results,the model can provide a quantitative approach to characterize the pressure-driven mold filling ability of aluminum alloy melt.The model is capable of describing the stop filling behavior of other aluminum alloys in pressure casting processes with corresponding rheological parameters and heat transfer coefficient.
基金Supported by National Natural Science Foundation of China(Grant No.51605058)Chongqing Research Program of Basic Research and Frontier Technology of China(Grant No.cstc2015jcyjBX0088)+2 种基金Fundamental Research Funds for the Central Universities of China(Grant No.106112016CDJCR021226)Six Talent Peaks Project in Jiangsu Province of China(Grant No.2014-ZBZZ-006)"Excellence Plans-Zijin Star" Foundation of Nanjing University of Science and Technology,China(Grant No.2015-zijin-07)
文摘CNC machining systems are inevitably confronted with frequent changes in energy behaviors because they are widely used to perform various machining tasks. It is a challenge to understand and analyze the flexible energy behaviors in CNC machining systems. A method to model flexible energy behaviors in CNC machining systems based on hierarchical objected-oriented Petri net(HOONet) is proposed. The structure of the HOONet is constructed of a high-level model and detail models. The former is used to model operational states for CNC machining systems, and the latter is used to analyze the component models for operational states. The machining parameters having great impacts on energy behaviors in CNC machining systems are declared with the data dictionary in HOONet models. A case study based on a CNC lathe is presented to demonstrate the proposed modeling method. The results show that it is effective for modeling flexible energy behaviors and providing a fine-grained description to quantitatively analyze the energy consumption of CNC machining systems.
文摘The thermomechanical behavior of precipitation-hardened aluminum alloy AA7022-T6 was studied using isothermal compression at temperatures of 623−773 K and strain rates of 0.01−1 s^−1.The experimental results indicated that dynamic recrystallization(DRX)is a predominant hot deformation mechanism,especially at elevated temperatures and low strain rates.The modified Johnson−Cook(J−C)and the strain compensated Arrhenius-type models were developed to predict the hot flow behavior under different deformation conditions.The correlation coefficients of modified J−C model and the strain compensated Arrhenius-type models were 0.9914 and 0.9972,respectively,their average relative errors(ARE)were 6.074%and 4.465%,respectively,and their root mean square errors(RMSE)were 10.611 and 1.665 MPa,respectively,indicating that the strain compensated Arrhenius-type model can predict the hot flow stress of AA7022-T6 aluminum alloy with an appropriate accuracy.
基金supported by National Key Research and Development Program of China (Grant No. 2016YFC1102402)National Natural Science Foundation of China (Grant No. 51431002 and 51871004)+1 种基金NSFC/RGC Joint Research Scheme (Grant No. 51661165014)Peking University Medicine Seed Fund for Interdisciplinary Research (Grant No. BMU2018ME005)
文摘Magnesium alloys have shown great potential for their use in the medical device field, due to the promising biodegradability. However, it remains a challenge to characterize the degradation behavior of the Mg alloys in a quantitative manner. As such, controlling the degradation rate of the Mg alloys as per our needs is still hard, which greatly limits the practical application of the Mg alloys as a degradable biomaterial.This paper discussed a numerical model developed based on the diffusion theory, which can capture the experimental degradation behavior of the Mg alloys precisely. The numerical model is then implemented into a finite element scheme, where the model is calibrated with the data from our previous studies on the corrosion of the as-cast Mg-1 Ca and the as-rolled Mg-3 Ge binary alloys. The degradation behavior of a pin implant is predicted using the calibrated model to demonstrate the model’s capability. A standard flow is provided in a practical framework for obtaining the degradation behavior of any biomedical Mg alloys. This methodology was further verified via the comparison with enormous available experimental results. Lastly, the material parameters defined in this model were provided as a new kind of material property.
