The acquisition of seabed physical parameters is one of the focuses of marine acoustic researches.However,the activesource ocean bottom seismometer(OBS)detection method in the marine geophysical research is rarely use...The acquisition of seabed physical parameters is one of the focuses of marine acoustic researches.However,the activesource ocean bottom seismometer(OBS)detection method in the marine geophysical research is rarely used to acquire seabed physical parameters,and less work is performed in the Arctic.In this study,two active-source OBS data collected from the 9th and 11th Chinese National Arctic Research Expedition(CHINARE)are selected to obtain the physical parameters of seabed sediments.Two kinds of energy spark are used as the active sources,while the cost function inversion method is used based on the arrival time difference between the reflected and direct waves.The thickness and sound velocity of the sediment layers are obtained by inversion,and the empirical formula is used to calculate the physical parameters of the seabed sediment,which are compared with the measured results.The cost function inversion method based on the time difference of arrival of the reflected and direct waves is tested to be effective and feasible in the inversion of seabed parameters from active-source OBS data.The method is further applied to obtain the physical parameters of Chukchi seabed sediments,which provides the idea and reference for the application of marine geophysical activesource OBS detection technology in the inversion of polar seabed physical parameters.展开更多
To analyze a multibody system composed of non-uniform beam and spring-mass subsystems, the model discretization is carried on by utilizing the finite element method（FEM）, the dynamic model of non-uniform beam is dev...To analyze a multibody system composed of non-uniform beam and spring-mass subsystems, the model discretization is carried on by utilizing the finite element method（FEM）, the dynamic model of non-uniform beam is developed by using the transfer matrix method of multibody system（MS-TMM）, the transfer matrix of non-u- niform beam is derived, and the natural frequencies are computed. Compared with the numerical assembly method （NAM）, the results by MS-TMM have good agreement with the results by FEM, and are better than the results by NAM. When using the high precision method, the global dynamic equations of the complex multibody system are not needed and the orders of involved system matrices are decreased greatly. For the investigation on the re- verse problem of the physical parameter identification of multibody system, MS-TMM and the optimization tech- nology based on genetic algorithms（GAs） are combined and extended. The identification problem is exchanged for an optimization problem, and it is formulated as a global minimum solution of the objective function with respect to natural frequencies of multibody system. At last, the numerical example of non-uniform beam with attach- ments is discussed, and the identification results indicate the feasibility and the effectivity of the proposed aop- proach.展开更多
The similarity criterion for water flooding reservoir flows is concerned with in the present paper. When finding out all the dimensionless variables governing this kind of flow, their physical meanings are subsequentl...The similarity criterion for water flooding reservoir flows is concerned with in the present paper. When finding out all the dimensionless variables governing this kind of flow, their physical meanings are subsequently elucidated. Then, a numerical approach of sensitivity analysis is adopted to quantify their corresponding dominance degree among the similarity parameters. In this way, we may finally identify major scaling law in different parameter range and demonstrate the respective effects of viscosity, permeability and injection rate.展开更多
To satisfy performance and long life requirements for hot forging die,Ni60-Cr3C2 composite coatings were prepared on the high-speed steel W6Mo5Cr4V2 using laser cladding technology.Laser clad coatings with different r...To satisfy performance and long life requirements for hot forging die,Ni60-Cr3C2 composite coatings were prepared on the high-speed steel W6Mo5Cr4V2 using laser cladding technology.Laser clad coatings with different ratios of Ni60：Cr3C2 were investigated by scanning electron microscopy（SEM）,X-ray diffraction（XRD）,energy-dispersive X-ray analysis（EDX） and micro-hardness tester,respectively.Specific heat capacity and thermal conductivity were measured by Laser Thermal Constant Meter.Thermal expansion coefficient and elastic modulus were measured by Dynamic Mechanical Thermal Analyzer and Electro-Hydraulic Servocontrolled Testing System,respectively.The results indicated that Ni60＋50wt% Cr3C2 composite coating had dense and homogeneous structure,as well as a metallurgical bonding with the substrate.With the increase of Cr3C2 content,volume of chromium-containing compounds in the composite coating increased,microhardness increased and microstructure refined.The thermal physical parameters results showed that Ni60＋50wt% Cr3C2 composite coating was overall worse than W6Mo5Cr4V2,but had a higher hot yield strength to alleviate hot fatigue and surface hot wear of hot forging die during hot forging and thus improve the service life of hot forging die.展开更多
Evolutionary computation based on the idea of biologic evolution is one type of global optimization algorithm that uses self-adaptation,self-organization and random searching to solve optimization problems.The evoluti...Evolutionary computation based on the idea of biologic evolution is one type of global optimization algorithm that uses self-adaptation,self-organization and random searching to solve optimization problems.The evolutionary-simplex algorithm is introduced in this paper.It contains floating encoding which combines the evolutionary computation and the simplex algorithm to overcome the problems encountered in the genetic algorithm and evolutionary strategy methods. Numerical experiments are performed using seven typical functions to verify the algorithm.An inverse analysis method to identify structural physical parameters based on incomplete dynamic responses obtained from the analysis in the time domain is presented by using the evolutionary-simplex algorithm.The modal evolutionary-simplex algorithm converted from the time domain to the modal domain is proposed to improve the inverse efficiency.Numerical calculations for a 50-DOF system show that when compared with other methods,the evolutionary-simplex algorithm offers advantages of high precision, efficient searching ability,strong ability to resist noise,independence of initial value,and good adaptation to incomplete information conditions.展开更多
During the growth of the hot filament chemical vapor deposition （HFCVD） diamond films, numerical simulations in a 2-D mathematical model were employed to investigate the influence of various deposition parameters on...During the growth of the hot filament chemical vapor deposition （HFCVD） diamond films, numerical simulations in a 2-D mathematical model were employed to investigate the influence of various deposition parameters on the gas physical parameters, including the temperature, velocity and volume density of gas. It was found that, even in the case of optimized deposition parameters, the space distributions of gas parameters were heterogeneous due primarily to the thermal blockage come from the hot filaments and cryogenic pump effect arisen from the cold reactor wall. The distribution of volume density agreed well with the thermal round-flow phenomenon, one of the key obstacles to obtaining high growth rate in HFCVD process. In virtue of isothermal boundary with high temperature or adiabatic boundary condition of reactor wall, however, the thermal roundflow was profoundly reduced and as a consequence, the uniformity of gas physical parameters was considerably improved, as identified by the experimental films growth.展开更多
As far as the accuracy of calculating unsteady temperature field is concerned, it is very important to find the accurate physical parameters such as specific heat, thermal conductivity, latent heat of phase transforma...As far as the accuracy of calculating unsteady temperature field is concerned, it is very important to find the accurate physical parameters such as specific heat, thermal conductivity, latent heat of phase transformation and surface heat flux. The model for calculating H and Q is established in this paper. The measurement methods and data processing for physical parameters such as volume specific heat C, thermal conductivity k, volume latent heat of phase transformation c1 and surface heat flux are introduced The physical parameters of 1Cr18Ni9Ti and 45 steels and the surface heat flux for 1 Cr18Ni9Ti probe cooled in water,10% NaCl water and oil with different temperatures are measured, respectively. These data show that the probability of absolute error less than 2* C between the calculated and measured values in temperature field calculation reaches above 80% if using the above physical parameters, which provides a reliable technology basis for precise calculation of temperature field.展开更多
Physical parameters are very important for vehicle dynamic modeling and analysis.However,most of physical parameter identification methods are assuming some physical parameters of vehicle are known,and the other unkno...Physical parameters are very important for vehicle dynamic modeling and analysis.However,most of physical parameter identification methods are assuming some physical parameters of vehicle are known,and the other unknown parameters can be identified.In order to identify physical parameters of vehicle in the case that all physical parameters are unknown,a methodology based on the State Variable Method（SVM） for physical parameter identification of two-axis on-road vehicle is presented.The modal parameters of the vehicle are identified by the SVM,furthermore,the physical parameters of the vehicle are estimated by least squares method.In numerical simulations,physical parameters of Ford Granada are chosen as parameters of vehicle model,and half-sine bump function is chosen to simulate tire stimulated by impulse excitation.The first numerical simulation shows that the present method can identify all of the physical parameters and the largest absolute value of percentage error of the identified physical parameter is 0.205%;and the effect of the errors of additional mass,structural parameter and measurement noise are discussed in the following simulations,the results shows that when signal contains 30 d B noise,the largest absolute value of percentage error of the identification is 3.78%.These simulations verify that the presented method is effective and accurate for physical parameter identification of two-axis on-road vehicles.The proposed methodology can identify all physical parameters of 7-DOF vehicle model by using free-decay responses of vehicle without need to assume some physical parameters are known.展开更多
The high temperature gas occurs behind shock or near the wall surface of vehicle in the hypersonic flight. As the temperature exceeds 2 000 K, 4 000 K, respectively, O2 and N2 molecules are successively dissociated. B...The high temperature gas occurs behind shock or near the wall surface of vehicle in the hypersonic flight. As the temperature exceeds 2 000 K, 4 000 K, respectively, O2 and N2 molecules are successively dissociated. Because of variable components at dif- ferent temperatures and pressures, the dissociated air is no longer a perfect gas, In this paper, a new method is developed to calculate accurate thermal physical parameters with the dissociation degree providing the thermochemical equilibrium procedure. Based on the dissociation degree, it is concluded that few numbers of equations and the solutions are easily obtained. In addition, a set of formulas relating the parameter to the dissociation degree are set up four-species, O2 molecule The thermodynamic properties of dissociated air containing and N2 molecule, O atom and N atom, are studied with the new method, and the results are consistent with those with the traditional equilibrium constant method. It is shown that this method is reliable for solving thermal physical parameters easily and directly.展开更多
This paper examines the influence of physical parameters on the collapse dynamics of a spherical bubble filled with diatomic gas(κ=7/5).The problem is formulated by the Rayleigh–Plesset dynamical equation,whose nume...This paper examines the influence of physical parameters on the collapse dynamics of a spherical bubble filled with diatomic gas(κ=7/5).The problem is formulated by the Rayleigh–Plesset dynamical equation,whose numerical solutions are carried out by Maple.Our studies show that each physical parameter affects the bubble collapse dynamics in different degree,which reveals that bubble collapse dynamics must considers all the parameters including liquid viscosity,surface tension,etc,else the outcome cannot be trusted.展开更多
To evaluate the downscaling ability with respect to tropical cyclones(TCs)near China and its sensitivity to the model physics representation,the authors performed a multi-physics ensemble simulation with the regional ...To evaluate the downscaling ability with respect to tropical cyclones(TCs)near China and its sensitivity to the model physics representation,the authors performed a multi-physics ensemble simulation with the regional Climate-Weather Research and Forecasting(CWRF)model at a 30 km resolution driven by ERA-Interim reanalysis data.The ensemble consisted of 28 integrations during 1979-2016 with varying CWRF physics configurations.Both CWRF and ERA-Interim can generally capture the seasonal cycle and interannual variation of the TC number near China,but evidently underestimate them.The CWRF downscaling and its multi-physics ensemble can notably reduce the underestimation and significantly improve the simulation of the TC occurrences.The skill enhancement is especially large in terms of the interannual variation,which is most sensitive to the cumulus scheme,followed by the boundary layer,surface and radiation schemes,but weakly sensitive to the cloud and microphysics schemes.Generally,the Noah surface scheme,CAML(CAM radiation scheme as implemented by Liang together with the diagnostic cloud cover scheme of Xu and Randall(1996))radiation scheme,prognostic cloud scheme,and Thompson microphysics scheme stand out for their better performance in simulating the interannual variation of TC number.However,the Emanuel cumulus and MYNN boundary layer schemes produce severe interannual biases.Our study provides a valuable reference for CWRF application to improve the understanding and prediction of TC activity.展开更多
[Objectives]To explore the correlation of processing technology,physical parameters and chemical components during plain stir-baking of Trichosanthis Radix.[Methods]Based on mixture uniform experiment design,the Trich...[Objectives]To explore the correlation of processing technology,physical parameters and chemical components during plain stir-baking of Trichosanthis Radix.[Methods]Based on mixture uniform experiment design,the Trichosanthis Radix was prepared by plain stir-bake method.Delphi method was used to evaluate and select the highest-scoring processed product for measuring physical parameters.UV spectrophotometry was used to determine the contents of starch and polysaccharide.The correlation and linear regression model of processing technology,physical parameters and chemical components were established with the aid of SPSS 26.0[Results]After processing by plain stir-bake method,the relative density and chromaticity showed a decreasing trend in the processed products of Trichosanthis Radix,the oxidation value,hydroscopic rate and swelling decreased firstly and then increased,and pH increased firstly and then decreased.The content of total starch decreased,the content of polysaccharide increased,and there was a negative correlation between them.There was a significant positive correlation between temperature and oxidation value,swelling and hydroscopic rate,hydroscopic rate and polysaccharide,and there was a significant negative correlation between relative density and hydroscopic rate or polysaccharide,total starch and hydroscopic rate or swelling.The linear relation model between processing technology and physical parameters and chemical components was r2>0.9.[Conclusions]After processing by plain stir-bake method,the physical parameters of Trichosanthis Radix changed,and there may be mutual conversion between total starch and polysaccharides.To a certain extent,physical parameters can be used to evaluate the quality of processed products of Trichosanthis Radix.This study is expected to provide a reference for research on quality evaluation of processed products of traditional Chinese medicine.展开更多
The effect of seasonal variations in physical parameters on quality of gravity flow water was investigated in Kyanamira Sub-County, Kabale District, Uganda. The seasonal variations in the physical parameters (pH, temp...The effect of seasonal variations in physical parameters on quality of gravity flow water was investigated in Kyanamira Sub-County, Kabale District, Uganda. The seasonal variations in the physical parameters (pH, temperature, electrical conductivity (EC), turbidity, colour, total dissolved solids (TDS), and total suspended solids (TSS)) were determined during wet and dry seasons. Composite samples from gravity flow water sources were collected monthly from March to August, 2014 and then analyzed. Temperature was measured using thermometer;pH, EC and TDS were determined using a multimeter, turbidity, colour and total suspended solids were determined by spectrophotometric method. TDS, pH and temperature were the most contributing parameters to water quality variations in both seasons. The mean pH values varied between 3.78 - 4.84 from March to August, 2014 at all study sites. These pH values were consistently below the WHO permissible range of 6.5 - 8.5. Similarly, total suspended solids varied between 0.66 - 2.17 mg·L<sup>-1</sup> and were well above the recommended WHO limit of zero mg·L<sup>-1</sup> at all study sites. Turbidity mean values varied between 0.83 - 3.7 NTU and were outside the recommended limits of 3 NTU at Kigata (3.7 NTU) only. Temperatures (20.3°C - 21.15°C) for all the study sites were within the recommended limit of 20°C - 30°C in water for domestic purposes. The mean values of physical parameters for the wet season were: temperature (21.12°C), colour (12.5 PtCoU), turbidity (3.4 NTU), TDS (76.76 mg·L<sup>-1</sup>), TSS (2.13 mg·L<sup>-1</sup>), pH (4.19) and EC (152.7 μS·cm<sup>-1</sup>) were different from those of the dry season (temperature (20.99°C), colour (0.93 PtCoU), turbidity (0.53 NTU), TDS (77.33 mg·L<sup>-1</sup>), TSS (0.67 mg·L<sup>-1</sup>), pH (4.86) and EC (158.65 μS·cm<sup>-1</sup>). Basing on these findings above, it was evident to justify discouraging the use of gravity flow water at these study sites for domestic purposes without proper treatment.展开更多
We are developing a nursing-care robot for physical care tasks. The concept of this robot is to promote the cared persons by the robot to activate their own motion ability as long as possible. This may lead to the imp...We are developing a nursing-care robot for physical care tasks. The concept of this robot is to promote the cared persons by the robot to activate their own motion ability as long as possible. This may lead to the improvement of the cared person＇s movement volition and movement abilities. In order to realize safe and human friendly robot care tasks, full body manipulation is an important technology, for which it is necessary to estimate the subject＇s center of gravity from the contact positions and forces with the robot＇s two arms. In this paper, we estimate the center of gravity of object based on the contact point and the contact force estimated by force sensor on both robot arms. The position of gravity center is important to realize care tasks stably. We performed experiments and simulations for the single point contact and dual points contact cases using a cylindrical object. As a result, it is found that although some errors were recognized in the experiments compared with the simulations, the relations between the contact positions and such errors were observed. Such experimental error mainly comes from the difference of shape between the real robot and the model of the robot in simulation.展开更多
Carbonate reservoirs have complex pore structures,which not only significantly affect the elastic properties and seismic responses of the reservoirs but also affect the accuracy of the prediction of the physical param...Carbonate reservoirs have complex pore structures,which not only significantly affect the elastic properties and seismic responses of the reservoirs but also affect the accuracy of the prediction of the physical parameters.The existing rockphysics inversion methods are mainly designed for clastic rocks,and the inversion objects are generally porosity and water saturation.The data used are primarily based on the elastic parameters,and the inversion methods are mainly linear approximations.To date,there has been a lack of a simultaneous pore structure and physical parameter inversion method for carbonate reservoirs.To solve these problems,a new Bayesian nonlinear simultaneous inversion method based on elastic impedance is proposed.This method integrates the differential effective medium model of multiple-porosity rocks,Gassmann equation,Amplitude Versus Offset(AVO)theory,Bayesian theory,and a nonlinear inversion algorithm to achieve the simultaneous quantitative prediction of the pore structure and physical parameters of complex porous reservoirs.The forward modeling indicates that the contribution of the pore structure,i.e.,the pore aspect ratio,to the AVO response and elastic impedance is second only to that of porosity and is far greater than that of water saturation.The application to real data shows that the new inversion method for determining the pore structure and physical parameters directly from pre-stack data can accurately predict a reservoir's porosity and water saturation and can evaluate the pore structure of the effective reservoir.展开更多
Lithium-ion battery anode used as silicon particles were obtained from different major suppliers,and they were characterized by different spectroscopic techniques and evaluated by electrochemical experiments.Correlati...Lithium-ion battery anode used as silicon particles were obtained from different major suppliers,and they were characterized by different spectroscopic techniques and evaluated by electrochemical experiments.Correlations between the key physical parameters and electrochemical properties of the silicon particles were investigated.Silicon particle size,surface oxygen content,-OH content and physical appearance are found to strongly influence the electrochemical properties of the Si anode.The particle size of 100 nm has great promise for the practical application of Si nanoparticles in the lithium-ion battery industry.An inverse correlation between the oxygen content and the reversible capacity or first coulombic efficiency was obtained.The-OH content by surface treatment contributes to enhanced cycling stability by the improved affinity between the Si particle and the water-soluble binder.Spherical Si particles perform better compared to irregular particles,and agglomeration dramatically decreases the cycling stability of the Si anode.Among the investigated Si particles,the sample that exhibited a reversible capacity of more than 2500 mAh g^(-1),a first coulombic efficiency of 89.26%and an excellent cycling stability,has great potential for use in the battery industry.展开更多
The pressurized electroslag remelting(PESR)process has a remarkable impact on manufacturing high nitrogen steels,which can alter the physical parameters of steels and solidification conditions at different atmospheric...The pressurized electroslag remelting(PESR)process has a remarkable impact on manufacturing high nitrogen steels,which can alter the physical parameters of steels and solidification conditions at different atmospheric pressures.The principle and applications of the PESR process are reviewed.The effect of atmospheric pressure,including Gibbs free energy,nitrogen solubility,melting point,viscosity,diffusion coefficient,partition coefficient,and nucleation rate,is explicitly expressed by empirical knowledge and quantified by thermodynamic relationships.The variation of interfacial heat transfer coefficient is discussed at different atmospheric pressures.Furthermore,the effect of atmospheric pressure on physical parameters of steels and solidification conditions during the PESR process is still in their embryonic research stage and it is important to do further study in this research field.Finally,a general concluding remark and suggestions for future development are proposed.展开更多
Because of complexity and non-predictability of the tunnel surrounding rock, the problem with the determination of the physical and mechanical parameters of the surrounding rock has become a main obstacle to theoretic...Because of complexity and non-predictability of the tunnel surrounding rock, the problem with the determination of the physical and mechanical parameters of the surrounding rock has become a main obstacle to theoretical research and numerical analysis in tunnel engineering. During design, it is a frequent practice, therefore, to give recommended values by analog based on experience. It is a key point in current research to make use of the displacement back analytic method to comparatively accurately determine the parameters of the surrounding rock whereas artificial intelligence possesses an exceptionally strong capability of identifying, expressing and coping with such complex non-linear relationships. The parameters can be verified by searching the optimal network structure, using back analysis on measured data to search optimal parameters and performing direct computation of the obtained results. In the current paper, the direct analysis is performed with the biological emulation system and the software of Fast Lagrangian Analysis of Continua (FLAC3D. The high non-linearity, network reasoning and coupling ability of the neural network are employed. The output vector required of the training of the neural network is obtained with the numerical analysis software. And the overall space search is conducted by employing the Adaptive Immunity Algorithm. As a result, we are able to avoid the shortcoming that multiple parameters and optimized parameters are easy to fall into a local extremum. At the same time, the computing speed and efficiency are increased as well. Further, in the paper satisfactory conclusions are arrived at through the intelligent direct-back analysis on the monitored and measured data at the Erdaoya tunneling project. The results show that the physical and mechanical parameters obtained by the intelligent direct-back analysis proposed in the current paper have effectively improved the recommended values in the original prospecting data. This is of practical significance to the appraisal of stability and informationization design of the surrounding rock.展开更多
This review focuses on thermodynamic and physical parameters,synthesis methods,and reported phases of Magnesium(Mg)containing high-entropy alloys(HEAs).Statistical data of publications concerning Mg-containing HEAs we...This review focuses on thermodynamic and physical parameters,synthesis methods,and reported phases of Magnesium(Mg)containing high-entropy alloys(HEAs).Statistical data of publications concerning Mg-containing HEAs were collected and analyzed.Data on the chemical elements included in Mg-containing HEAs,their theoretical end experimental densities,thermodynamic parameters,physical parameters,fabricated techniques and reported phases were also collected and discussed.On the basis of this information,a new classification for HEAs was proposed.It is also shown that the existing thermodynamic parameters cannot accurately predict the formation of a single phase solid solution for Mg-containing HEAs.The physical parameters of Mg-containing HEAs are within a wide range,and most of the synthesized Mg-containing HEAs have a complex multiphase structure.展开更多
Simulating the total ionizing dose(TID)of an electrical system using transistor-level models can be difficult and expensive,particularly for digital-integrated circuits(ICs).In this study,a method for modeling TID eff...Simulating the total ionizing dose(TID)of an electrical system using transistor-level models can be difficult and expensive,particularly for digital-integrated circuits(ICs).In this study,a method for modeling TID effects in complementary metaloxide semiconductor(CMOS)digital ICs based on the input/output buffer information specification(IBIS)was proposed.The digital IC was first divided into three parts based on its internal structure:the input buffer,output buffer,and functional area.Each of these three parts was separately modeled.Using the IBIS model,the transistor V-I characteristic curves of the buffers were processed,and the physical parameters were extracted and modeled using VHDL-AMS.In the functional area,logic functions were modeled in VHDL according to the data sheet.A golden digital IC model was developed by combining the input buffer,output buffer,and functional area models.Furthermore,the golden ratio was reconstructed based on TID experimental data,enabling the assessment of TID effects on the threshold voltage,carrier mobility,and time series of the digital IC.TID experiments were conducted using a CMOS non-inverting multiplexer,NC7SZ157,and the results were compared with the simulation results,which showed that the relative errors were less than 2%at each dose point.This confirms the practicality and accuracy of the proposed modeling method.The TID effect model for digital ICs developed using this modeling technique includes both the logical function of the IC and changes in electrical properties and functional degradation impacted by TID,which has potential applications in the design of radiation-hardening tolerance in digital ICs.展开更多
基金supported by the National Key R&D Program of China(No.2021YFC2801200)the National Natural Science Foundation of China(No.42076224)the Fundamental Research Funds for the Central Universities(No.201964015)。
文摘The acquisition of seabed physical parameters is one of the focuses of marine acoustic researches.However,the activesource ocean bottom seismometer(OBS)detection method in the marine geophysical research is rarely used to acquire seabed physical parameters,and less work is performed in the Arctic.In this study,two active-source OBS data collected from the 9th and 11th Chinese National Arctic Research Expedition(CHINARE)are selected to obtain the physical parameters of seabed sediments.Two kinds of energy spark are used as the active sources,while the cost function inversion method is used based on the arrival time difference between the reflected and direct waves.The thickness and sound velocity of the sediment layers are obtained by inversion,and the empirical formula is used to calculate the physical parameters of the seabed sediment,which are compared with the measured results.The cost function inversion method based on the time difference of arrival of the reflected and direct waves is tested to be effective and feasible in the inversion of seabed parameters from active-source OBS data.The method is further applied to obtain the physical parameters of Chukchi seabed sediments,which provides the idea and reference for the application of marine geophysical activesource OBS detection technology in the inversion of polar seabed physical parameters.
基金Supported by the National Natural Science Foundation of China(10902051)the Natural Science Foundation of Jiangsu Province(BK2008046)~~
文摘To analyze a multibody system composed of non-uniform beam and spring-mass subsystems, the model discretization is carried on by utilizing the finite element method（FEM）, the dynamic model of non-uniform beam is developed by using the transfer matrix method of multibody system（MS-TMM）, the transfer matrix of non-u- niform beam is derived, and the natural frequencies are computed. Compared with the numerical assembly method （NAM）, the results by MS-TMM have good agreement with the results by FEM, and are better than the results by NAM. When using the high precision method, the global dynamic equations of the complex multibody system are not needed and the orders of involved system matrices are decreased greatly. For the investigation on the re- verse problem of the physical parameter identification of multibody system, MS-TMM and the optimization tech- nology based on genetic algorithms（GAs） are combined and extended. The identification problem is exchanged for an optimization problem, and it is formulated as a global minimum solution of the objective function with respect to natural frequencies of multibody system. At last, the numerical example of non-uniform beam with attach- ments is discussed, and the identification results indicate the feasibility and the effectivity of the proposed aop- proach.
基金The project supported by the Innovative Project of CAS (KJCX-SW-L08)the National Basic Research Program of China(973)
文摘The similarity criterion for water flooding reservoir flows is concerned with in the present paper. When finding out all the dimensionless variables governing this kind of flow, their physical meanings are subsequently elucidated. Then, a numerical approach of sensitivity analysis is adopted to quantify their corresponding dominance degree among the similarity parameters. In this way, we may finally identify major scaling law in different parameter range and demonstrate the respective effects of viscosity, permeability and injection rate.
基金Funded by the National Natural Science Foundation of China (No.50675165)the Fundamental Research Funds for the Central Universities (No.2010-II-025)
文摘To satisfy performance and long life requirements for hot forging die,Ni60-Cr3C2 composite coatings were prepared on the high-speed steel W6Mo5Cr4V2 using laser cladding technology.Laser clad coatings with different ratios of Ni60：Cr3C2 were investigated by scanning electron microscopy（SEM）,X-ray diffraction（XRD）,energy-dispersive X-ray analysis（EDX） and micro-hardness tester,respectively.Specific heat capacity and thermal conductivity were measured by Laser Thermal Constant Meter.Thermal expansion coefficient and elastic modulus were measured by Dynamic Mechanical Thermal Analyzer and Electro-Hydraulic Servocontrolled Testing System,respectively.The results indicated that Ni60＋50wt% Cr3C2 composite coating had dense and homogeneous structure,as well as a metallurgical bonding with the substrate.With the increase of Cr3C2 content,volume of chromium-containing compounds in the composite coating increased,microhardness increased and microstructure refined.The thermal physical parameters results showed that Ni60＋50wt% Cr3C2 composite coating was overall worse than W6Mo5Cr4V2,but had a higher hot yield strength to alleviate hot fatigue and surface hot wear of hot forging die during hot forging and thus improve the service life of hot forging die.
基金National Natural Science Foundation of China(Grant No.50278006)
文摘Evolutionary computation based on the idea of biologic evolution is one type of global optimization algorithm that uses self-adaptation,self-organization and random searching to solve optimization problems.The evolutionary-simplex algorithm is introduced in this paper.It contains floating encoding which combines the evolutionary computation and the simplex algorithm to overcome the problems encountered in the genetic algorithm and evolutionary strategy methods. Numerical experiments are performed using seven typical functions to verify the algorithm.An inverse analysis method to identify structural physical parameters based on incomplete dynamic responses obtained from the analysis in the time domain is presented by using the evolutionary-simplex algorithm.The modal evolutionary-simplex algorithm converted from the time domain to the modal domain is proposed to improve the inverse efficiency.Numerical calculations for a 50-DOF system show that when compared with other methods,the evolutionary-simplex algorithm offers advantages of high precision, efficient searching ability,strong ability to resist noise,independence of initial value,and good adaptation to incomplete information conditions.
基金This work was partially supported by the National Natural Science Foundation of China （NSFC） under Contract No. 59292800 the Science and Technology Committee of Liaoning Province.
文摘During the growth of the hot filament chemical vapor deposition （HFCVD） diamond films, numerical simulations in a 2-D mathematical model were employed to investigate the influence of various deposition parameters on the gas physical parameters, including the temperature, velocity and volume density of gas. It was found that, even in the case of optimized deposition parameters, the space distributions of gas parameters were heterogeneous due primarily to the thermal blockage come from the hot filaments and cryogenic pump effect arisen from the cold reactor wall. The distribution of volume density agreed well with the thermal round-flow phenomenon, one of the key obstacles to obtaining high growth rate in HFCVD process. In virtue of isothermal boundary with high temperature or adiabatic boundary condition of reactor wall, however, the thermal roundflow was profoundly reduced and as a consequence, the uniformity of gas physical parameters was considerably improved, as identified by the experimental films growth.
文摘As far as the accuracy of calculating unsteady temperature field is concerned, it is very important to find the accurate physical parameters such as specific heat, thermal conductivity, latent heat of phase transformation and surface heat flux. The model for calculating H and Q is established in this paper. The measurement methods and data processing for physical parameters such as volume specific heat C, thermal conductivity k, volume latent heat of phase transformation c1 and surface heat flux are introduced The physical parameters of 1Cr18Ni9Ti and 45 steels and the surface heat flux for 1 Cr18Ni9Ti probe cooled in water,10% NaCl water and oil with different temperatures are measured, respectively. These data show that the probability of absolute error less than 2* C between the calculated and measured values in temperature field calculation reaches above 80% if using the above physical parameters, which provides a reliable technology basis for precise calculation of temperature field.
基金Supported by National Natural Science Foundation of China(Grant Nos.51175157,U124208)
文摘Physical parameters are very important for vehicle dynamic modeling and analysis.However,most of physical parameter identification methods are assuming some physical parameters of vehicle are known,and the other unknown parameters can be identified.In order to identify physical parameters of vehicle in the case that all physical parameters are unknown,a methodology based on the State Variable Method（SVM） for physical parameter identification of two-axis on-road vehicle is presented.The modal parameters of the vehicle are identified by the SVM,furthermore,the physical parameters of the vehicle are estimated by least squares method.In numerical simulations,physical parameters of Ford Granada are chosen as parameters of vehicle model,and half-sine bump function is chosen to simulate tire stimulated by impulse excitation.The first numerical simulation shows that the present method can identify all of the physical parameters and the largest absolute value of percentage error of the identified physical parameter is 0.205%;and the effect of the errors of additional mass,structural parameter and measurement noise are discussed in the following simulations,the results shows that when signal contains 30 d B noise,the largest absolute value of percentage error of the identification is 3.78%.These simulations verify that the presented method is effective and accurate for physical parameter identification of two-axis on-road vehicles.The proposed methodology can identify all physical parameters of 7-DOF vehicle model by using free-decay responses of vehicle without need to assume some physical parameters are known.
基金supported by the National Natural Science Foundation of China(Nos.11732011,11672205,and 11332007)the National Key Research and Development Program of China(No.2016YFA0401200)
文摘The high temperature gas occurs behind shock or near the wall surface of vehicle in the hypersonic flight. As the temperature exceeds 2 000 K, 4 000 K, respectively, O2 and N2 molecules are successively dissociated. Because of variable components at dif- ferent temperatures and pressures, the dissociated air is no longer a perfect gas, In this paper, a new method is developed to calculate accurate thermal physical parameters with the dissociation degree providing the thermochemical equilibrium procedure. Based on the dissociation degree, it is concluded that few numbers of equations and the solutions are easily obtained. In addition, a set of formulas relating the parameter to the dissociation degree are set up four-species, O2 molecule The thermodynamic properties of dissociated air containing and N2 molecule, O atom and N atom, are studied with the new method, and the results are consistent with those with the traditional equilibrium constant method. It is shown that this method is reliable for solving thermal physical parameters easily and directly.
文摘This paper examines the influence of physical parameters on the collapse dynamics of a spherical bubble filled with diatomic gas(κ=7/5).The problem is formulated by the Rayleigh–Plesset dynamical equation,whose numerical solutions are carried out by Maple.Our studies show that each physical parameter affects the bubble collapse dynamics in different degree,which reveals that bubble collapse dynamics must considers all the parameters including liquid viscosity,surface tension,etc,else the outcome cannot be trusted.
基金supported by the National Climate Center of China under Grants 2211011816501。
文摘To evaluate the downscaling ability with respect to tropical cyclones(TCs)near China and its sensitivity to the model physics representation,the authors performed a multi-physics ensemble simulation with the regional Climate-Weather Research and Forecasting(CWRF)model at a 30 km resolution driven by ERA-Interim reanalysis data.The ensemble consisted of 28 integrations during 1979-2016 with varying CWRF physics configurations.Both CWRF and ERA-Interim can generally capture the seasonal cycle and interannual variation of the TC number near China,but evidently underestimate them.The CWRF downscaling and its multi-physics ensemble can notably reduce the underestimation and significantly improve the simulation of the TC occurrences.The skill enhancement is especially large in terms of the interannual variation,which is most sensitive to the cumulus scheme,followed by the boundary layer,surface and radiation schemes,but weakly sensitive to the cloud and microphysics schemes.Generally,the Noah surface scheme,CAML(CAM radiation scheme as implemented by Liang together with the diagnostic cloud cover scheme of Xu and Randall(1996))radiation scheme,prognostic cloud scheme,and Thompson microphysics scheme stand out for their better performance in simulating the interannual variation of TC number.However,the Emanuel cumulus and MYNN boundary layer schemes produce severe interannual biases.Our study provides a valuable reference for CWRF application to improve the understanding and prediction of TC activity.
基金Science and Technology Research and Development Project of Chengde City,Hebei Province(201706A043)Young Scholar Program of Hebei Pharmaceutical Association Hospital Pharmaceutical Research Project(2020—Hbsyxhqn0029)Public Health Service Subsidy Fund Project of Chinese Medicine Department,State Administration of Traditional Chinese Medicine(Guo Zhong Yi Gui Cai Fa[2015]No.21).
文摘[Objectives]To explore the correlation of processing technology,physical parameters and chemical components during plain stir-baking of Trichosanthis Radix.[Methods]Based on mixture uniform experiment design,the Trichosanthis Radix was prepared by plain stir-bake method.Delphi method was used to evaluate and select the highest-scoring processed product for measuring physical parameters.UV spectrophotometry was used to determine the contents of starch and polysaccharide.The correlation and linear regression model of processing technology,physical parameters and chemical components were established with the aid of SPSS 26.0[Results]After processing by plain stir-bake method,the relative density and chromaticity showed a decreasing trend in the processed products of Trichosanthis Radix,the oxidation value,hydroscopic rate and swelling decreased firstly and then increased,and pH increased firstly and then decreased.The content of total starch decreased,the content of polysaccharide increased,and there was a negative correlation between them.There was a significant positive correlation between temperature and oxidation value,swelling and hydroscopic rate,hydroscopic rate and polysaccharide,and there was a significant negative correlation between relative density and hydroscopic rate or polysaccharide,total starch and hydroscopic rate or swelling.The linear relation model between processing technology and physical parameters and chemical components was r2>0.9.[Conclusions]After processing by plain stir-bake method,the physical parameters of Trichosanthis Radix changed,and there may be mutual conversion between total starch and polysaccharides.To a certain extent,physical parameters can be used to evaluate the quality of processed products of Trichosanthis Radix.This study is expected to provide a reference for research on quality evaluation of processed products of traditional Chinese medicine.
文摘The effect of seasonal variations in physical parameters on quality of gravity flow water was investigated in Kyanamira Sub-County, Kabale District, Uganda. The seasonal variations in the physical parameters (pH, temperature, electrical conductivity (EC), turbidity, colour, total dissolved solids (TDS), and total suspended solids (TSS)) were determined during wet and dry seasons. Composite samples from gravity flow water sources were collected monthly from March to August, 2014 and then analyzed. Temperature was measured using thermometer;pH, EC and TDS were determined using a multimeter, turbidity, colour and total suspended solids were determined by spectrophotometric method. TDS, pH and temperature were the most contributing parameters to water quality variations in both seasons. The mean pH values varied between 3.78 - 4.84 from March to August, 2014 at all study sites. These pH values were consistently below the WHO permissible range of 6.5 - 8.5. Similarly, total suspended solids varied between 0.66 - 2.17 mg·L<sup>-1</sup> and were well above the recommended WHO limit of zero mg·L<sup>-1</sup> at all study sites. Turbidity mean values varied between 0.83 - 3.7 NTU and were outside the recommended limits of 3 NTU at Kigata (3.7 NTU) only. Temperatures (20.3°C - 21.15°C) for all the study sites were within the recommended limit of 20°C - 30°C in water for domestic purposes. The mean values of physical parameters for the wet season were: temperature (21.12°C), colour (12.5 PtCoU), turbidity (3.4 NTU), TDS (76.76 mg·L<sup>-1</sup>), TSS (2.13 mg·L<sup>-1</sup>), pH (4.19) and EC (152.7 μS·cm<sup>-1</sup>) were different from those of the dry season (temperature (20.99°C), colour (0.93 PtCoU), turbidity (0.53 NTU), TDS (77.33 mg·L<sup>-1</sup>), TSS (0.67 mg·L<sup>-1</sup>), pH (4.86) and EC (158.65 μS·cm<sup>-1</sup>). Basing on these findings above, it was evident to justify discouraging the use of gravity flow water at these study sites for domestic purposes without proper treatment.
文摘We are developing a nursing-care robot for physical care tasks. The concept of this robot is to promote the cared persons by the robot to activate their own motion ability as long as possible. This may lead to the improvement of the cared person＇s movement volition and movement abilities. In order to realize safe and human friendly robot care tasks, full body manipulation is an important technology, for which it is necessary to estimate the subject＇s center of gravity from the contact positions and forces with the robot＇s two arms. In this paper, we estimate the center of gravity of object based on the contact point and the contact force estimated by force sensor on both robot arms. The position of gravity center is important to realize care tasks stably. We performed experiments and simulations for the single point contact and dual points contact cases using a cylindrical object. As a result, it is found that although some errors were recognized in the experiments compared with the simulations, the relations between the contact positions and such errors were observed. Such experimental error mainly comes from the difference of shape between the real robot and the model of the robot in simulation.
基金supported by the National Key Research and Development Program of China(Grant No.2019YFC0605504)the Scientific Research&Technology Development Project of China National Petroleum Corporation(Grant No.2017D-3504)。
文摘Carbonate reservoirs have complex pore structures,which not only significantly affect the elastic properties and seismic responses of the reservoirs but also affect the accuracy of the prediction of the physical parameters.The existing rockphysics inversion methods are mainly designed for clastic rocks,and the inversion objects are generally porosity and water saturation.The data used are primarily based on the elastic parameters,and the inversion methods are mainly linear approximations.To date,there has been a lack of a simultaneous pore structure and physical parameter inversion method for carbonate reservoirs.To solve these problems,a new Bayesian nonlinear simultaneous inversion method based on elastic impedance is proposed.This method integrates the differential effective medium model of multiple-porosity rocks,Gassmann equation,Amplitude Versus Offset(AVO)theory,Bayesian theory,and a nonlinear inversion algorithm to achieve the simultaneous quantitative prediction of the pore structure and physical parameters of complex porous reservoirs.The forward modeling indicates that the contribution of the pore structure,i.e.,the pore aspect ratio,to the AVO response and elastic impedance is second only to that of porosity and is far greater than that of water saturation.The application to real data shows that the new inversion method for determining the pore structure and physical parameters directly from pre-stack data can accurately predict a reservoir's porosity and water saturation and can evaluate the pore structure of the effective reservoir.
基金The authors are very grateful to the National Natural Science Foundation of China(NSFC no.21875154 and 21473120)for funding.
文摘Lithium-ion battery anode used as silicon particles were obtained from different major suppliers,and they were characterized by different spectroscopic techniques and evaluated by electrochemical experiments.Correlations between the key physical parameters and electrochemical properties of the silicon particles were investigated.Silicon particle size,surface oxygen content,-OH content and physical appearance are found to strongly influence the electrochemical properties of the Si anode.The particle size of 100 nm has great promise for the practical application of Si nanoparticles in the lithium-ion battery industry.An inverse correlation between the oxygen content and the reversible capacity or first coulombic efficiency was obtained.The-OH content by surface treatment contributes to enhanced cycling stability by the improved affinity between the Si particle and the water-soluble binder.Spherical Si particles perform better compared to irregular particles,and agglomeration dramatically decreases the cycling stability of the Si anode.Among the investigated Si particles,the sample that exhibited a reversible capacity of more than 2500 mAh g^(-1),a first coulombic efficiency of 89.26%and an excellent cycling stability,has great potential for use in the battery industry.
基金The authors gratefully express their appreciation to the National Natural Science Foundation of China(Nos.U1960203,51974153,and 52174317).
文摘The pressurized electroslag remelting(PESR)process has a remarkable impact on manufacturing high nitrogen steels,which can alter the physical parameters of steels and solidification conditions at different atmospheric pressures.The principle and applications of the PESR process are reviewed.The effect of atmospheric pressure,including Gibbs free energy,nitrogen solubility,melting point,viscosity,diffusion coefficient,partition coefficient,and nucleation rate,is explicitly expressed by empirical knowledge and quantified by thermodynamic relationships.The variation of interfacial heat transfer coefficient is discussed at different atmospheric pressures.Furthermore,the effect of atmospheric pressure on physical parameters of steels and solidification conditions during the PESR process is still in their embryonic research stage and it is important to do further study in this research field.Finally,a general concluding remark and suggestions for future development are proposed.
基金supported by the National Natural Science Foundation of China (No.50609028)
文摘Because of complexity and non-predictability of the tunnel surrounding rock, the problem with the determination of the physical and mechanical parameters of the surrounding rock has become a main obstacle to theoretical research and numerical analysis in tunnel engineering. During design, it is a frequent practice, therefore, to give recommended values by analog based on experience. It is a key point in current research to make use of the displacement back analytic method to comparatively accurately determine the parameters of the surrounding rock whereas artificial intelligence possesses an exceptionally strong capability of identifying, expressing and coping with such complex non-linear relationships. The parameters can be verified by searching the optimal network structure, using back analysis on measured data to search optimal parameters and performing direct computation of the obtained results. In the current paper, the direct analysis is performed with the biological emulation system and the software of Fast Lagrangian Analysis of Continua (FLAC3D. The high non-linearity, network reasoning and coupling ability of the neural network are employed. The output vector required of the training of the neural network is obtained with the numerical analysis software. And the overall space search is conducted by employing the Adaptive Immunity Algorithm. As a result, we are able to avoid the shortcoming that multiple parameters and optimized parameters are easy to fall into a local extremum. At the same time, the computing speed and efficiency are increased as well. Further, in the paper satisfactory conclusions are arrived at through the intelligent direct-back analysis on the monitored and measured data at the Erdaoya tunneling project. The results show that the physical and mechanical parameters obtained by the intelligent direct-back analysis proposed in the current paper have effectively improved the recommended values in the original prospecting data. This is of practical significance to the appraisal of stability and informationization design of the surrounding rock.
基金supported by the Office of Scientific Research of Shandong Vocational and Technical University of International Studies.
文摘This review focuses on thermodynamic and physical parameters,synthesis methods,and reported phases of Magnesium(Mg)containing high-entropy alloys(HEAs).Statistical data of publications concerning Mg-containing HEAs were collected and analyzed.Data on the chemical elements included in Mg-containing HEAs,their theoretical end experimental densities,thermodynamic parameters,physical parameters,fabricated techniques and reported phases were also collected and discussed.On the basis of this information,a new classification for HEAs was proposed.It is also shown that the existing thermodynamic parameters cannot accurately predict the formation of a single phase solid solution for Mg-containing HEAs.The physical parameters of Mg-containing HEAs are within a wide range,and most of the synthesized Mg-containing HEAs have a complex multiphase structure.
基金This work was supported by the special fund of the State Key Laboratory of Intense Pulsed Radiation Simulation and Effect(No.SKLIPR2011).
文摘Simulating the total ionizing dose(TID)of an electrical system using transistor-level models can be difficult and expensive,particularly for digital-integrated circuits(ICs).In this study,a method for modeling TID effects in complementary metaloxide semiconductor(CMOS)digital ICs based on the input/output buffer information specification(IBIS)was proposed.The digital IC was first divided into three parts based on its internal structure:the input buffer,output buffer,and functional area.Each of these three parts was separately modeled.Using the IBIS model,the transistor V-I characteristic curves of the buffers were processed,and the physical parameters were extracted and modeled using VHDL-AMS.In the functional area,logic functions were modeled in VHDL according to the data sheet.A golden digital IC model was developed by combining the input buffer,output buffer,and functional area models.Furthermore,the golden ratio was reconstructed based on TID experimental data,enabling the assessment of TID effects on the threshold voltage,carrier mobility,and time series of the digital IC.TID experiments were conducted using a CMOS non-inverting multiplexer,NC7SZ157,and the results were compared with the simulation results,which showed that the relative errors were less than 2%at each dose point.This confirms the practicality and accuracy of the proposed modeling method.The TID effect model for digital ICs developed using this modeling technique includes both the logical function of the IC and changes in electrical properties and functional degradation impacted by TID,which has potential applications in the design of radiation-hardening tolerance in digital ICs.
