The high-speed winding spindle employs a flexible support system incorporating rubber O-rings.By precisely configuring the structural parameters and the number of the O-rings,the spindle can stably surpass its critica...The high-speed winding spindle employs a flexible support system incorporating rubber O-rings.By precisely configuring the structural parameters and the number of the O-rings,the spindle can stably surpass its critical speed points and maintain operational stability across the entire working speed range.However,the support stiffness and damping of rubber O-rings exhibit significant nonlinear frequency dependence.Conventional experimental methods for deriving equivalent stiffness and damping,based on the principle of the forced non-resonance method,require fabricating custom setups for each O-ring specification and conducting vibration tests at varying frequencies,resulting in low efficiency and high costs.This study proposes a hybrid simulation-experimental method for dynamic parameter identification.Firstly,the frequency-dependent dynamic parameters of a specific O-ring support system are experimentally obtained.Subsequently,a corresponding parametric finite element model is established to simulate and solve the equivalent elastic modulus and equivalent stiffness-damping coefficient of this O-ring support system.Ultimately,after iterative simulation,the simulated and experimental results achieve a 99.7%agreement.The parametric finite element model developed herein can directly simulate and inversely estimate frequency-dependent dynamic parameters for O-rings of different specifications but identical elastic modulus.展开更多
The dynamic parameters for internal solitary waves(ISWs)derived from the extended Korteweg-de Vries(eKdV)equation play an important role in the understanding and prediction of ISWs.The spatiotemporal variations of the...The dynamic parameters for internal solitary waves(ISWs)derived from the extended Korteweg-de Vries(eKdV)equation play an important role in the understanding and prediction of ISWs.The spatiotemporal variations of the dynamic parameters of the ISWs in the northern South China Sea(SCS)were studied based on the reanalysis of long-term temperature and salinity datasets.The results for spectrum analysis show that there are definite geographical differences for the periodic variation of the parameters:in shallow water,all parameters vary with a wave period of one year,while in deep water wave components of the parameters at other frequencies exist.Using wavelet analysis,the wavelet power spectral densities in deep water exhibited an inter-annual variation pattern.For example,the wave component of the dispersion coefficient with a wave period of about half a year reached its power peak once every two years.Based on previous work,this inter-annual variation pattern was deduced to be caused by dynamic processes.In further work on the regulatory mechanisms,empirical orthogonal function(EOF)decomposition was performed.It was found that the modes of the dispersion coefficient have different geographical distributions,explaining the reason why the wave components in different frequencies appeared in different locations.The numerical simulation results confirm that the variations in the parameters of the ISWs derived from the eKdV equation could affect the waveforms significantly because of changes in the polarity of the ISWs.Therefore,the periodic variations of the dynamic parameters are related to the geographical location because of dynamic processes operating.展开更多
In order to analyze and simulate the complex super-plastic forming process by computer, a method of equal height bulging for determining material parameters m and K of the superplastic alloy is presented. The formulae...In order to analyze and simulate the complex super-plastic forming process by computer, a method of equal height bulging for determining material parameters m and K of the superplastic alloy is presented. The formulae related to the method are deduced in this paper. The accuracy of the method is available for evaluating the examples used in simulating the superplastic sheet-metal bulging processes.展开更多
The investigation of leachate-contaminated clay(LCC)is essential for landfill engineering assessment and achievement of sustainable development goals.Several static and dynamic laboratory tests,including unconfined co...The investigation of leachate-contaminated clay(LCC)is essential for landfill engineering assessment and achievement of sustainable development goals.Several static and dynamic laboratory tests,including unconfined compressive strength(UCS),California bearing ratio(CBR),and cyclic simple shear,are conducted.Cyclic simple shear experiments on LCCs were performed to evaluate the damping and shear modulus.The investigated factors are vertical load(VL),leachate content(LC),frequency(F),and shear strain(ShS)for LCC.Forensic-based investigation optimization(FBIO)and equilibrium optimizer algorithm(EOA)were utilized in addition to multiple types of ensemble models,including adaptive boosting(ADB),gradient boosting regression tree(GBRT),extreme gradient boosting(XGB) and random forest(RF).The comparison of the methods showed that GBRT-FBIO and XGB-EOA models outperformed other models for shear modulus and damping of LCC.The p-value less than 0.0001 shows the significance of the used models in the response surface methodology(RSM)method.展开更多
Purpose:The major limitation of tumor microwave ablation(MWA)operation is the lack of predictability of the ablation zone before surgery.Operators rely on their individual experience to select a treatment plan,which i...Purpose:The major limitation of tumor microwave ablation(MWA)operation is the lack of predictability of the ablation zone before surgery.Operators rely on their individual experience to select a treatment plan,which is prone to either inadequate or excessive ablation.This paper aims to establish an ablation prediction model that guides MWA tumor surgical planning.Methods:An MWA process was first simulated by incorporating electromagnetic radiation equations,thermal equations,and optimized biological tissue parameters(dynamic dielectric and thermophysical parameters).The temperature distributions(the short/long diameters,and the total volume of the ablation zone)were then generated and verified by 60 cases ex vivo porcine liver experiments.Subsequently,a series of data were obtained from the simulated temperature distributions and to further fit the novel ablation coagulated area prediction model(ACAPM),thus rendering the ablation-dose table for the guiding surgical plan.The MWA clinical patient data and clinical devices suggested data were used to validate the accuracy and practicability of the established predicted model.Results:The 60 cases ex vivo porcine liver experiments demonstrated the accuracy of the simulated temperature distributions.Compared to traditional simulation methods,our approach reduces the long-diameter error of the ablation zone from 1.1 cm to 0.29 cm,achieving a 74%reduction in error.Further,the clinical data including the patients'operation results and devices provided values were consistent well with our predicated data,indicating the great potential of ACAPM to assist preoperative planning.展开更多
To study the influence of temperature and water content on ultrasonic wave velocity and to establish the relationship between ultrasonic wave velocity and frozen silty clay strength, ultrasonic tests were conducted to...To study the influence of temperature and water content on ultrasonic wave velocity and to establish the relationship between ultrasonic wave velocity and frozen silty clay strength, ultrasonic tests were conducted to frozen silty clay by using RSM-SY5（T） nonmetal supersonic test meter, and the tensile strength and compressive strength of silty clay were measured under various negative temperatures. Test and analysis results indicate that, ultrasonic wave velocity rapidly changes in the temperature range of-1 ℃ to -5 ℃. Ultrasonic wave velocity increased with an increase of water content until the water content reached the critical water content, while decreased with an increase of water content after the water content exceeded the critical water content. This study showed that there was strong positive correlation between the ul- trasonic wave velocity and the frozen soil strength. As ultrasonic wave velocity increased, either tensile strength or com- pressive strength increased. Based on the experimental data, the relationship between ultrasonic wave velocity and frozen silty clay strength was obtained through regression analysis. It was found that the ultrasonic test technique can be used to test frozen soils and lay the foundation for the determination of frozen soil strength.展开更多
According to the characteristic of elastic waves propagation in medium and the application of elastic waves method in rock mass engineering, the cranny mass with random crannies was regarded as quasi-isotropic cranny ...According to the characteristic of elastic waves propagation in medium and the application of elastic waves method in rock mass engineering, the cranny mass with random crannies was regarded as quasi-isotropic cranny mass. In accordance with the rock rupture mechanics, principle of energy balance and Castiglano＇s theorem, the relationship of effective dynamic parameters of elasticity （E, v, G） and cranny density parameters or porosity was put forward. On this basis, through the theory of elastic waves propagation in isotropic medium, the relationship between the elastic wave velocity and cranny density parameters and porosity was set up. The theoretical research results show that, in this kind of cranny rock masses, there is nonlinear relationships between the effective dynamic parameters of elasticity and wave velocities and the cranny density parameter or porosity; and with the increase of cranny density parameter or porosity of cranny rock masses, the effective dynamic modulus and the elastic wave velocities of cranny rock masses will decrease; and at the same time, when the cranny density parameter or porosity is very small, the effective dynamic modulus of elasticity and the elastic wave velocities change with the cranny density parameter, which can explain the sensitivity of effective elastic parameters and elastic wave velocities to cranny rock masses.展开更多
According to theory of photoautotrophic micro-propagation, and principle and technology of environmental engineering, an automatic control and regulation under photoautotrophic micro-propagation by plants was designed...According to theory of photoautotrophic micro-propagation, and principle and technology of environmental engineering, an automatic control and regulation under photoautotrophic micro-propagation by plants was designed, which can be used for planting condition optimization of photoautotrophic micro-propagation and qualified industrialized production of seedlings.展开更多
Based on Matsuoka＇s central pattern generator （CPG） model and taking quadruped as an example, the dynamics of CPG model was investigated through the single-parameter-analysis method and the numerical simulation tec...Based on Matsuoka＇s central pattern generator （CPG） model and taking quadruped as an example, the dynamics of CPG model was investigated through the single-parameter-analysis method and the numerical simulation technique. Simulation results indicate that the CPG model exhibits complex dynamics, while each parameter has specifically definitive influence trends on the CPG output. These conclusions were applied to control a quadrupedal robot to walk in different gaits, clear obstacle, and walk up- and down-slope successfully.展开更多
Gas hydrate(hereinafter,"hydrate"for short)in the marine environment mostly lies in weakly consolidated sediments,so its undisturbed coring is difficult and costly.In view of this,it is necessary to understa...Gas hydrate(hereinafter,"hydrate"for short)in the marine environment mostly lies in weakly consolidated sediments,so its undisturbed coring is difficult and costly.In view of this,it is necessary to understand the relationship between acoustic properties and elastic mechanical properties of hydrates through laboratory experiments.In this paper,samples of hydrate sediments were prepared indoors.Then,petrophysical experiments were carried out on these samples to measure the electric parameters and acoustic parameters of hydrate sediments.Finally,according to the theory of elasticity,the dynamic elastic mechanical parameters under three axial compressions,three particle sizes and three shale contents were calculated to analyze their effects on the dynamic elastic mechanical parameters of hydrate sediments under different conditions.And the following research results were obtained.First,when the hydrate saturation is in a certain range,it is in a proportional relationship with the elastic parameters of sediments.Second,when the hydrate saturation is constant,the dynamic Young's modulus of hydrate sediments increases,but the Poisson's ratio has little to do with the axial compression as particle sizes(0.125-1.180 mm)and axial compression increase and shale content decreases.Third,a model of the relationship between the elastic parameters and the shale content and axial compression is established.In conclusion,the dynamic elastic mechanical indexes of gas hydrate obtained from the acoustic logging methodology will solve the above difficulties and the research results provide a reference for calculating the mechanical properties of hydrate sediments by use of logging data.展开更多
The dynamic parameter identification of the robot is the basis for the design of the controller based on the dynamic model.Currently,the primary method for solving angular velocity and angular acceleration is to filte...The dynamic parameter identification of the robot is the basis for the design of the controller based on the dynamic model.Currently,the primary method for solving angular velocity and angular acceleration is to filter and smooth the position sequence and then form a differential signal.However,if the noise and the original signal overlap in the frequency domain,filtering the noise will also filter out the valuable information in the frequency band.This paper proposes an excitation trajectory based on Logistic function,which fully uses the information in the original signal and can accurately solve the angular velocity and angular acceleration without filtering and smoothing the position sequence.The joint angle of the excitation trajectory is mapped to the joint angular velocity and angular acceleration one by one so that the joint angular velocity and joint angular acceleration can be obtained directly according to the position.The genetic algorithm is used to optimize the excitation trajectory parameters to minimize the observation matrix’s condition number and further improve the identification accuracy.By using the strategy of iterative identification,the dynamic parameters identified in each iteration are substituted into the robot controller according to the previous position sequence until the tracking trajectory approaches the desired trajectory,and the actual joint angular velocity and angular acceleration converge to the expected value.The simulation results show that using the step-by-step strategy,the joint angular velocity and joint angular acceleration of the tracking trajectory quickly converge to the expected value,and the identification error of inertia parameters is less than 0.01 in three iterations.With the increase of the number of iterations,the identification error of inertial parameters can be further reduced.展开更多
The mathematical ignition model was established and researches ofignition dynamic parameters for coke in some typical coal samplesfrom cement plants was carried out according to circumstances of coalcom- busted in cem...The mathematical ignition model was established and researches ofignition dynamic parameters for coke in some typical coal samplesfrom cement plants was carried out according to circumstances of coalcom- busted in cement plants. In order to get the ignitionintemperature T_pi of carbon particles more accurately, the tem-perature rising experimental method was used and the actual heatingcircumstances for pulverized coal in calciners (in cement plants)werealso considered.展开更多
In the analysis of the system of anchoring bar and wall rock in small strain and longitudinal vibration dynamic response, the influence of the cement grouting as well as the rock layer on the anchor bar can be evaluat...In the analysis of the system of anchoring bar and wall rock in small strain and longitudinal vibration dynamic response, the influence of the cement grouting as well as the rock layer on the anchor bar can be evaluated as the two kinds of parameters: the dynamic stiffness and the damp, which are the vital reference of the anchorage quality. Based on the analytic solution to the dynamic equation of the integrated anchor bar, the new approach which combines genetic algorithm and the toolbox of Matlab is applied to solve the problem of multi-parameters reverse deduction for integrated anchorage system in dynamic testing. Using the traits of the self-organizing, self-adapting and the fast convergence speed of the genetic algorithm, the optimum of all possible solutions to dynamic parameters is obtained by calculating the project instances. Examples show that the method presented in this paper is effective and reliable.展开更多
Based on the principle of the electric-magnetic check-measure, this paper puts forward a new technology and method that use the magnetic marks to check and measure the dynamic physical parameters such as angle speed, ...Based on the principle of the electric-magnetic check-measure, this paper puts forward a new technology and method that use the magnetic marks to check and measure the dynamic physical parameters such as angle speed, bending strain,stress and bending moment. The principles of the check-measure and the dealing and exchanging technology about signals have been demonstrated and the rotating components have been made up. The timely and quantitative check-measure of the dynamic physical parameters during the component in working has been realized by using computer control.展开更多
The Tianjin coastal area is a typical soft soil region,where the soil is a marine deposit of the late Quaternary.The soil dynamic parameters from seismic risk assessment reports are collected,and drilling of 15 holes ...The Tianjin coastal area is a typical soft soil region,where the soil is a marine deposit of the late Quaternary.The soil dynamic parameters from seismic risk assessment reports are collected,and drilling of 15 holes was carried out to sample the soils and measure their dynamic characteristics.The data was divided into 7 types based on lithology,namely,muddy clay,muddy silty clay,silt,silty clay,clay,silty sand and fine sand.Statistics of the dynamic parameters of these soils are collected to obtain the mean values of dynamic shear modulus ratio and damping ratio at different depths.Then,two typical drill holes are selected to establish the soil dynamic models to investigate the seismic response in different cases.The dynamic seismic responses of soil are calculated using the statistical values of this paper,and the values of Code(1994) and those recommended by Yuan Xiaoming et al.(2000),respectively.The applicability and pertinence of the statistical value obtained in this paper are demonstrated by the response spectrum shape,peak ground acceleration and response spectral characteristics.The results can be taken as a reference of the soil dynamic value in this area and can be used in the seismic risk assessment of engineering projects.展开更多
Soil dynamic parameters,including dynamic shear modulus ratio and damping ratio,have important effects on the results of layered soil earthquake response. In this paper,the mean parameter values of silty clay in diffe...Soil dynamic parameters,including dynamic shear modulus ratio and damping ratio,have important effects on the results of layered soil earthquake response. In this paper,the mean parameter values of silty clay in different depths are obtained after statistical analysis of the experimental soil dynamic data from 20 recent site seismic safety evaluation reports in the Beijing area. Furthermore,based on two typical engineering sites,the influence of four different soil dynamic parameters,the statistic mean values,experimental values, values recommended by Yuan Xiaoming,and the values recommended in the code for seismic safety evaluation of engineering sites( DB001-94) are analyzed. The result shows that mean statistical values are applicable to seismic safety evaluation work in the Beijing area,especially for some inter-layered silty clays whose undisturbed soil samples are hard to obtain.展开更多
In this paper, we study the initial-boundary value problem with rigid wall for the equations in combustion dynamics with largy parameter. Introducing variable scalar norms and two seminorms, making use of the vorticit...In this paper, we study the initial-boundary value problem with rigid wall for the equations in combustion dynamics with largy parameter. Introducing variable scalar norms and two seminorms, making use of the vorticity operator, overcome the difficulty from the large parameter. By energy estimation, the existence and unique theorems of local smooth solution is proved.展开更多
In this paper, dynamic soil parameters derived from Dalian area seismic risk assessment reports are collected. In this study, the measurement data is divided into 7 types, i.e. silty clay, muddy silty clay, clay, medi...In this paper, dynamic soil parameters derived from Dalian area seismic risk assessment reports are collected. In this study, the measurement data is divided into 7 types, i.e. silty clay, muddy silty clay, clay, medium sand, rock fragments, backfill soil and fully-weathered slate. Statistics of the dynamic parameters of these soils are carried out to obtain the mean values of dynamic shear modulus ratio and damping ratio. Typical drill holes are selected to establish dynamic soil models to investigate the seismic response for various cases. The dynamic parameters of the models are taken from the statistical values of this study, the standard values of code 94 (i.e. the dynamic soil parameters for Dalian seismic microzonation), and the recommended values by Yuan Xiaoming et al. (2000) respectively. The calculated results of peak ground acceleration are compared with the response spectral characteristics. The results show that the statistical values are approximate to the values recommended by Yuan Xiaoming, et al. (2000), but different greatly with the standard values in code 94.展开更多
Source spectra,corner frequency and zero frequency amplitudes in near-source conditions were measured using waveform data from 989 earthquakes with magnitudes larger than ML2.0 observed by the Beijing Digital Telemetr...Source spectra,corner frequency and zero frequency amplitudes in near-source conditions were measured using waveform data from 989 earthquakes with magnitudes larger than ML2.0 observed by the Beijing Digital Telemetry Seismic Network in the Capital Circle Region of China and its surrounding areas from January 2002 to June 2006 by the Brune model.Relevant formulas that were used for the calculation of dynamic source parameters include rupture radius,seismic moment,seismic energy,stress drop,and apparent stress.Scaling relations and characteristics of temporal-spatial variations of these dynamic parameters before the MS5.1 Wenan earthquake in Hebei Province that occurred on July 20,2006 were analyzed.Results show that apparent stress,stress drop,and the ratio of seismic energy to the rupture radius had relatively high values in some areas before the Wenan earthquake.These high-value concentration areas were mainly distributed in the North China Plain seismic zone.As is seen from the time curves,parameters,such as apparent stress,stress drop,and ratio of seismic energy to rupture radius underwent significant ascending processes before the Wenan earthquake,but the variation in the corner frequency showed a descending trend.This result might be related to the enhancement of stress in the North China Plain seismic zone before the earthquake.展开更多
As an important component of oil-immersed transformers,the bushing's internal insu-lation ageing and dampness after the long-term operation can cause changes in the in-ternal electric and temperature fields,seriou...As an important component of oil-immersed transformers,the bushing's internal insu-lation ageing and dampness after the long-term operation can cause changes in the in-ternal electric and temperature fields,seriously threatening its safe operation.This paper tested the power frequency permittivity and direct current conductivity of aged and damp oil-paper insulation samples at different testing temperatures,and constructed a dynamic dielectric parameter calculation model.Meanwhile,a simulation model was established based on the actual structure of the 252 kV/1250 A bushing which is mainly used for the oil-immersed high-voltage bushings of 110 kV and above.The electric-magnetic-thermal multi-physical fields were used for simulation analysis.The influence of ageing/moisture(different degrees of dampness in the upper and lower regions)on the electric field distribution in the bushing was obtained.During the initial to steady-state process,the electric field distribution at the zero and end shield shows a reversal phenomenon.When the capacitor core has different degrees of dampness in the upper and lower regions,the impedance distribution of the capacitor core is non-uniform.This phenomenon will lead to an increase in the radial electric field gradient at the end shield of the capacitor core,which is prone to the risk of slip-flashing discharge.In summary,this paper adopts the field-induced dynamic parameters method to analyse the changes of multi-physical fields in the bushing.This can provide theoretical guidance for optimising the bushing structure and on-site maintenance.展开更多
基金National Key R&D Program of China(No.2017YFB1304000)Fundamental Research Funds for the Central Universities,China(No.2232023G-05-1)。
文摘The high-speed winding spindle employs a flexible support system incorporating rubber O-rings.By precisely configuring the structural parameters and the number of the O-rings,the spindle can stably surpass its critical speed points and maintain operational stability across the entire working speed range.However,the support stiffness and damping of rubber O-rings exhibit significant nonlinear frequency dependence.Conventional experimental methods for deriving equivalent stiffness and damping,based on the principle of the forced non-resonance method,require fabricating custom setups for each O-ring specification and conducting vibration tests at varying frequencies,resulting in low efficiency and high costs.This study proposes a hybrid simulation-experimental method for dynamic parameter identification.Firstly,the frequency-dependent dynamic parameters of a specific O-ring support system are experimentally obtained.Subsequently,a corresponding parametric finite element model is established to simulate and solve the equivalent elastic modulus and equivalent stiffness-damping coefficient of this O-ring support system.Ultimately,after iterative simulation,the simulated and experimental results achieve a 99.7%agreement.The parametric finite element model developed herein can directly simulate and inversely estimate frequency-dependent dynamic parameters for O-rings of different specifications but identical elastic modulus.
基金Supported by the Hunan Provincial Science Fund for Distinguished Young Scholars(No.2023JJ10053)the National Natural Science Foundation of China(No.42276205)。
文摘The dynamic parameters for internal solitary waves(ISWs)derived from the extended Korteweg-de Vries(eKdV)equation play an important role in the understanding and prediction of ISWs.The spatiotemporal variations of the dynamic parameters of the ISWs in the northern South China Sea(SCS)were studied based on the reanalysis of long-term temperature and salinity datasets.The results for spectrum analysis show that there are definite geographical differences for the periodic variation of the parameters:in shallow water,all parameters vary with a wave period of one year,while in deep water wave components of the parameters at other frequencies exist.Using wavelet analysis,the wavelet power spectral densities in deep water exhibited an inter-annual variation pattern.For example,the wave component of the dispersion coefficient with a wave period of about half a year reached its power peak once every two years.Based on previous work,this inter-annual variation pattern was deduced to be caused by dynamic processes.In further work on the regulatory mechanisms,empirical orthogonal function(EOF)decomposition was performed.It was found that the modes of the dispersion coefficient have different geographical distributions,explaining the reason why the wave components in different frequencies appeared in different locations.The numerical simulation results confirm that the variations in the parameters of the ISWs derived from the eKdV equation could affect the waveforms significantly because of changes in the polarity of the ISWs.Therefore,the periodic variations of the dynamic parameters are related to the geographical location because of dynamic processes operating.
文摘In order to analyze and simulate the complex super-plastic forming process by computer, a method of equal height bulging for determining material parameters m and K of the superplastic alloy is presented. The formulae related to the method are deduced in this paper. The accuracy of the method is available for evaluating the examples used in simulating the superplastic sheet-metal bulging processes.
文摘The investigation of leachate-contaminated clay(LCC)is essential for landfill engineering assessment and achievement of sustainable development goals.Several static and dynamic laboratory tests,including unconfined compressive strength(UCS),California bearing ratio(CBR),and cyclic simple shear,are conducted.Cyclic simple shear experiments on LCCs were performed to evaluate the damping and shear modulus.The investigated factors are vertical load(VL),leachate content(LC),frequency(F),and shear strain(ShS)for LCC.Forensic-based investigation optimization(FBIO)and equilibrium optimizer algorithm(EOA)were utilized in addition to multiple types of ensemble models,including adaptive boosting(ADB),gradient boosting regression tree(GBRT),extreme gradient boosting(XGB) and random forest(RF).The comparison of the methods showed that GBRT-FBIO and XGB-EOA models outperformed other models for shear modulus and damping of LCC.The p-value less than 0.0001 shows the significance of the used models in the response surface methodology(RSM)method.
基金supported by the National Major Scientific Instruments and Equipment Development Project Funded by the National Natural Science Foundation of China(81827803)the Jiangsu Province Key Research and Development Program(Social Development)Project(BE2020705).
文摘Purpose:The major limitation of tumor microwave ablation(MWA)operation is the lack of predictability of the ablation zone before surgery.Operators rely on their individual experience to select a treatment plan,which is prone to either inadequate or excessive ablation.This paper aims to establish an ablation prediction model that guides MWA tumor surgical planning.Methods:An MWA process was first simulated by incorporating electromagnetic radiation equations,thermal equations,and optimized biological tissue parameters(dynamic dielectric and thermophysical parameters).The temperature distributions(the short/long diameters,and the total volume of the ablation zone)were then generated and verified by 60 cases ex vivo porcine liver experiments.Subsequently,a series of data were obtained from the simulated temperature distributions and to further fit the novel ablation coagulated area prediction model(ACAPM),thus rendering the ablation-dose table for the guiding surgical plan.The MWA clinical patient data and clinical devices suggested data were used to validate the accuracy and practicability of the established predicted model.Results:The 60 cases ex vivo porcine liver experiments demonstrated the accuracy of the simulated temperature distributions.Compared to traditional simulation methods,our approach reduces the long-diameter error of the ablation zone from 1.1 cm to 0.29 cm,achieving a 74%reduction in error.Further,the clinical data including the patients'operation results and devices provided values were consistent well with our predicated data,indicating the great potential of ACAPM to assist preoperative planning.
基金supported by the National Natural Science Foundation of China (No.41271080 and No.41230630)the Western Project Program of the Chinese Academy of Sciences(KZCX2-XB3-19)the open fund of Qinghai Research and Observation Base, Key Laboratory of Highway Construction and Maintenance Technology in Permafrost Region Ministry of Transport, PRC (2012-12-4)
文摘To study the influence of temperature and water content on ultrasonic wave velocity and to establish the relationship between ultrasonic wave velocity and frozen silty clay strength, ultrasonic tests were conducted to frozen silty clay by using RSM-SY5（T） nonmetal supersonic test meter, and the tensile strength and compressive strength of silty clay were measured under various negative temperatures. Test and analysis results indicate that, ultrasonic wave velocity rapidly changes in the temperature range of-1 ℃ to -5 ℃. Ultrasonic wave velocity increased with an increase of water content until the water content reached the critical water content, while decreased with an increase of water content after the water content exceeded the critical water content. This study showed that there was strong positive correlation between the ul- trasonic wave velocity and the frozen soil strength. As ultrasonic wave velocity increased, either tensile strength or com- pressive strength increased. Based on the experimental data, the relationship between ultrasonic wave velocity and frozen silty clay strength was obtained through regression analysis. It was found that the ultrasonic test technique can be used to test frozen soils and lay the foundation for the determination of frozen soil strength.
基金Projects(50334060 50474025) supported by the National Natural Science Foundation of China project(2005CB221502)supported by the National Key Fundamental Research and Development Programof China
文摘According to the characteristic of elastic waves propagation in medium and the application of elastic waves method in rock mass engineering, the cranny mass with random crannies was regarded as quasi-isotropic cranny mass. In accordance with the rock rupture mechanics, principle of energy balance and Castiglano＇s theorem, the relationship of effective dynamic parameters of elasticity （E, v, G） and cranny density parameters or porosity was put forward. On this basis, through the theory of elastic waves propagation in isotropic medium, the relationship between the elastic wave velocity and cranny density parameters and porosity was set up. The theoretical research results show that, in this kind of cranny rock masses, there is nonlinear relationships between the effective dynamic parameters of elasticity and wave velocities and the cranny density parameter or porosity; and with the increase of cranny density parameter or porosity of cranny rock masses, the effective dynamic modulus and the elastic wave velocities of cranny rock masses will decrease; and at the same time, when the cranny density parameter or porosity is very small, the effective dynamic modulus of elasticity and the elastic wave velocities change with the cranny density parameter, which can explain the sensitivity of effective elastic parameters and elastic wave velocities to cranny rock masses.
基金Supported by Agriculture Development Program for Science and Technology in Guangdong Province(2009B020405003)~~
文摘According to theory of photoautotrophic micro-propagation, and principle and technology of environmental engineering, an automatic control and regulation under photoautotrophic micro-propagation by plants was designed, which can be used for planting condition optimization of photoautotrophic micro-propagation and qualified industrialized production of seedlings.
文摘Based on Matsuoka＇s central pattern generator （CPG） model and taking quadruped as an example, the dynamics of CPG model was investigated through the single-parameter-analysis method and the numerical simulation technique. Simulation results indicate that the CPG model exhibits complex dynamics, while each parameter has specifically definitive influence trends on the CPG output. These conclusions were applied to control a quadrupedal robot to walk in different gaits, clear obstacle, and walk up- and down-slope successfully.
基金supported by the National Key R&D Program of China“New technology for solid fluidization testing of marine gas hydrate”(No.:2016YFC0304008).
文摘Gas hydrate(hereinafter,"hydrate"for short)in the marine environment mostly lies in weakly consolidated sediments,so its undisturbed coring is difficult and costly.In view of this,it is necessary to understand the relationship between acoustic properties and elastic mechanical properties of hydrates through laboratory experiments.In this paper,samples of hydrate sediments were prepared indoors.Then,petrophysical experiments were carried out on these samples to measure the electric parameters and acoustic parameters of hydrate sediments.Finally,according to the theory of elasticity,the dynamic elastic mechanical parameters under three axial compressions,three particle sizes and three shale contents were calculated to analyze their effects on the dynamic elastic mechanical parameters of hydrate sediments under different conditions.And the following research results were obtained.First,when the hydrate saturation is in a certain range,it is in a proportional relationship with the elastic parameters of sediments.Second,when the hydrate saturation is constant,the dynamic Young's modulus of hydrate sediments increases,but the Poisson's ratio has little to do with the axial compression as particle sizes(0.125-1.180 mm)and axial compression increase and shale content decreases.Third,a model of the relationship between the elastic parameters and the shale content and axial compression is established.In conclusion,the dynamic elastic mechanical indexes of gas hydrate obtained from the acoustic logging methodology will solve the above difficulties and the research results provide a reference for calculating the mechanical properties of hydrate sediments by use of logging data.
基金supported by Aeronautical Science Foundation of China(No.201916052001)China National Key R&D Program(No.2018YFB1309203)Foundation of the Graduate Innovation Center,Nanjing University of Aeronautics and Astronautics(No.xcxjh20210501)。
文摘The dynamic parameter identification of the robot is the basis for the design of the controller based on the dynamic model.Currently,the primary method for solving angular velocity and angular acceleration is to filter and smooth the position sequence and then form a differential signal.However,if the noise and the original signal overlap in the frequency domain,filtering the noise will also filter out the valuable information in the frequency band.This paper proposes an excitation trajectory based on Logistic function,which fully uses the information in the original signal and can accurately solve the angular velocity and angular acceleration without filtering and smoothing the position sequence.The joint angle of the excitation trajectory is mapped to the joint angular velocity and angular acceleration one by one so that the joint angular velocity and joint angular acceleration can be obtained directly according to the position.The genetic algorithm is used to optimize the excitation trajectory parameters to minimize the observation matrix’s condition number and further improve the identification accuracy.By using the strategy of iterative identification,the dynamic parameters identified in each iteration are substituted into the robot controller according to the previous position sequence until the tracking trajectory approaches the desired trajectory,and the actual joint angular velocity and angular acceleration converge to the expected value.The simulation results show that using the step-by-step strategy,the joint angular velocity and joint angular acceleration of the tracking trajectory quickly converge to the expected value,and the identification error of inertia parameters is less than 0.01 in three iterations.With the increase of the number of iterations,the identification error of inertial parameters can be further reduced.
文摘The mathematical ignition model was established and researches ofignition dynamic parameters for coke in some typical coal samplesfrom cement plants was carried out according to circumstances of coalcom- busted in cement plants. In order to get the ignitionintemperature T_pi of carbon particles more accurately, the tem-perature rising experimental method was used and the actual heatingcircumstances for pulverized coal in calciners (in cement plants)werealso considered.
基金Funded by the Natural Science Foundation of China (50378096) and Key Technology Item of Education Ministry (03138).
文摘In the analysis of the system of anchoring bar and wall rock in small strain and longitudinal vibration dynamic response, the influence of the cement grouting as well as the rock layer on the anchor bar can be evaluated as the two kinds of parameters: the dynamic stiffness and the damp, which are the vital reference of the anchorage quality. Based on the analytic solution to the dynamic equation of the integrated anchor bar, the new approach which combines genetic algorithm and the toolbox of Matlab is applied to solve the problem of multi-parameters reverse deduction for integrated anchorage system in dynamic testing. Using the traits of the self-organizing, self-adapting and the fast convergence speed of the genetic algorithm, the optimum of all possible solutions to dynamic parameters is obtained by calculating the project instances. Examples show that the method presented in this paper is effective and reliable.
文摘Based on the principle of the electric-magnetic check-measure, this paper puts forward a new technology and method that use the magnetic marks to check and measure the dynamic physical parameters such as angle speed, bending strain,stress and bending moment. The principles of the check-measure and the dealing and exchanging technology about signals have been demonstrated and the rotating components have been made up. The timely and quantitative check-measure of the dynamic physical parameters during the component in working has been realized by using computer control.
基金sponsored by the State-level Public Welfare Scientific Research Courtyard Basic Scientific Research ProgramInstitute of Crustal Dynamics+1 种基金CEA (ZDJ2009-07ZDJ2009-23)
文摘The Tianjin coastal area is a typical soft soil region,where the soil is a marine deposit of the late Quaternary.The soil dynamic parameters from seismic risk assessment reports are collected,and drilling of 15 holes was carried out to sample the soils and measure their dynamic characteristics.The data was divided into 7 types based on lithology,namely,muddy clay,muddy silty clay,silt,silty clay,clay,silty sand and fine sand.Statistics of the dynamic parameters of these soils are collected to obtain the mean values of dynamic shear modulus ratio and damping ratio at different depths.Then,two typical drill holes are selected to establish the soil dynamic models to investigate the seismic response in different cases.The dynamic seismic responses of soil are calculated using the statistical values of this paper,and the values of Code(1994) and those recommended by Yuan Xiaoming et al.(2000),respectively.The applicability and pertinence of the statistical value obtained in this paper are demonstrated by the response spectrum shape,peak ground acceleration and response spectral characteristics.The results can be taken as a reference of the soil dynamic value in this area and can be used in the seismic risk assessment of engineering projects.
基金sponsored jointly by the Research Grants from Institute of Crustal Dynamics,CEA(NO. ZDJ2007-7)the 2007 Special Research Project 8-50 of the Department of Finance
文摘Soil dynamic parameters,including dynamic shear modulus ratio and damping ratio,have important effects on the results of layered soil earthquake response. In this paper,the mean parameter values of silty clay in different depths are obtained after statistical analysis of the experimental soil dynamic data from 20 recent site seismic safety evaluation reports in the Beijing area. Furthermore,based on two typical engineering sites,the influence of four different soil dynamic parameters,the statistic mean values,experimental values, values recommended by Yuan Xiaoming,and the values recommended in the code for seismic safety evaluation of engineering sites( DB001-94) are analyzed. The result shows that mean statistical values are applicable to seismic safety evaluation work in the Beijing area,especially for some inter-layered silty clays whose undisturbed soil samples are hard to obtain.
文摘In this paper, we study the initial-boundary value problem with rigid wall for the equations in combustion dynamics with largy parameter. Introducing variable scalar norms and two seminorms, making use of the vorticity operator, overcome the difficulty from the large parameter. By energy estimation, the existence and unique theorems of local smooth solution is proved.
文摘In this paper, dynamic soil parameters derived from Dalian area seismic risk assessment reports are collected. In this study, the measurement data is divided into 7 types, i.e. silty clay, muddy silty clay, clay, medium sand, rock fragments, backfill soil and fully-weathered slate. Statistics of the dynamic parameters of these soils are carried out to obtain the mean values of dynamic shear modulus ratio and damping ratio. Typical drill holes are selected to establish dynamic soil models to investigate the seismic response for various cases. The dynamic parameters of the models are taken from the statistical values of this study, the standard values of code 94 (i.e. the dynamic soil parameters for Dalian seismic microzonation), and the recommended values by Yuan Xiaoming et al. (2000) respectively. The calculated results of peak ground acceleration are compared with the response spectral characteristics. The results show that the statistical values are approximate to the values recommended by Yuan Xiaoming, et al. (2000), but different greatly with the standard values in code 94.
基金the Special Research Fund for Earthquake Science,China (200708023)
文摘Source spectra,corner frequency and zero frequency amplitudes in near-source conditions were measured using waveform data from 989 earthquakes with magnitudes larger than ML2.0 observed by the Beijing Digital Telemetry Seismic Network in the Capital Circle Region of China and its surrounding areas from January 2002 to June 2006 by the Brune model.Relevant formulas that were used for the calculation of dynamic source parameters include rupture radius,seismic moment,seismic energy,stress drop,and apparent stress.Scaling relations and characteristics of temporal-spatial variations of these dynamic parameters before the MS5.1 Wenan earthquake in Hebei Province that occurred on July 20,2006 were analyzed.Results show that apparent stress,stress drop,and the ratio of seismic energy to the rupture radius had relatively high values in some areas before the Wenan earthquake.These high-value concentration areas were mainly distributed in the North China Plain seismic zone.As is seen from the time curves,parameters,such as apparent stress,stress drop,and ratio of seismic energy to rupture radius underwent significant ascending processes before the Wenan earthquake,but the variation in the corner frequency showed a descending trend.This result might be related to the enhancement of stress in the North China Plain seismic zone before the earthquake.
基金National Natural Science Foundation of China,Grant/Award Number:52307164Heilongjiang Provincial Natural Science Foundation of China,Grant/Award Number:YQ2024E044。
文摘As an important component of oil-immersed transformers,the bushing's internal insu-lation ageing and dampness after the long-term operation can cause changes in the in-ternal electric and temperature fields,seriously threatening its safe operation.This paper tested the power frequency permittivity and direct current conductivity of aged and damp oil-paper insulation samples at different testing temperatures,and constructed a dynamic dielectric parameter calculation model.Meanwhile,a simulation model was established based on the actual structure of the 252 kV/1250 A bushing which is mainly used for the oil-immersed high-voltage bushings of 110 kV and above.The electric-magnetic-thermal multi-physical fields were used for simulation analysis.The influence of ageing/moisture(different degrees of dampness in the upper and lower regions)on the electric field distribution in the bushing was obtained.During the initial to steady-state process,the electric field distribution at the zero and end shield shows a reversal phenomenon.When the capacitor core has different degrees of dampness in the upper and lower regions,the impedance distribution of the capacitor core is non-uniform.This phenomenon will lead to an increase in the radial electric field gradient at the end shield of the capacitor core,which is prone to the risk of slip-flashing discharge.In summary,this paper adopts the field-induced dynamic parameters method to analyse the changes of multi-physical fields in the bushing.This can provide theoretical guidance for optimising the bushing structure and on-site maintenance.
