The dynamics of soil organic carbon (SOC) was analyzed by using laboratory incubation and double exponential model that mineralizable SOC was separated into active carbon pools and slow carbon pools in forest soils ...The dynamics of soil organic carbon (SOC) was analyzed by using laboratory incubation and double exponential model that mineralizable SOC was separated into active carbon pools and slow carbon pools in forest soils derived from Changbai and Qilian Mountain areas. By analyzing and fitting the CO2 evolved rates with SOC mineralization, the results showed that active carbon pools accounted tor 1.0% to 8.5% of SOC with an average of mean resistant times (MRTs) for 24 days, and slow carbon pools accounted for 91% to 99% of SOC with an average of MRTs for 179 years. The sizes and MRTs of slow carbon pools showed that SOC in Qilian Mountain sites was more difficult to decompose than that in Changbai Mountain sites. By analyzing the effects of temperature, soil clay content and elevation on SOC mineralization, results indicated that mineralization of SOC was directly related to temperature and that content of accumulated SOC and size of slow carbon pools from Changbai Mountain and Qilian Mountain sites increased linearly with increasing clay content, respectively, which showed temperature and clay content could make greater effect on mineralization of SOC.展开更多
Nucleus-nucleus potentials are determined in the framework of double folding model for M3Y-Reid and M3Y- Paris effective nucleon-nucleon (NN) interactions. Both zero-range and finite-range exchange parts of NN inter...Nucleus-nucleus potentials are determined in the framework of double folding model for M3Y-Reid and M3Y- Paris effective nucleon-nucleon (NN) interactions. Both zero-range and finite-range exchange parts of NN interactions are considered in the folding procedure. In this paper the spherical projectile-spherical target system 16O+^2008Pb is selected for calculating the barrier energies, fusion cross sections and barrier distributions with the density-independent and density-dependent NN interactions on the basis of M3Y-Reid and M3Y Paris NN interactions. The barrier energies become lower for Paris NN interactions in comparison with Reid NN interactions, and also for finite-range exchange part in comparison with zero-range exchange part. The density-dependent NN interactions give similar fusion cross sections and barrier distributions, and the density-independent NN interaction causes the barrier distribution moving to a higher position. However, the density-independent Reid NN interaction with zero-range exchange part gives the lowest fusion cross sections. We find that the calculated fusion cross sections and the barrier distributions are in agreement with the experimental data after renormalization of the nuclear potential due to coupled-channel effect.展开更多
This research appraises comparative analysis between single diode and double diode model of photovoltaic (PV) solar cells to enhance the conversion efficiency of power engendering PV solar systems. Single diode model ...This research appraises comparative analysis between single diode and double diode model of photovoltaic (PV) solar cells to enhance the conversion efficiency of power engendering PV solar systems. Single diode model is simple and easy to implement, whereas double diode model has better accuracy which acquiesces for more precise forecast of PV systems performance. Exploration is done on the basis of simulation results and MATLAB tool is used to serve this purpose. Simulations are performed by varying distinct model parameters such as solar irradiance, temperature, value of parasitic resistances, ideality factor of diode and number of series and parallel connected solar cells used to assemble PV array. Conspicuous demonstration is executed to analyze effects of these specifications on the efficiency curve and power vs. voltage output characteristics of PV cell for specified models.展开更多
This paper discusses the valuation of the Credit Default Swap based on a jump market, in which the asset price of a firm follows a double exponential jump diffusion process, the value of the debt is driven by a geomet...This paper discusses the valuation of the Credit Default Swap based on a jump market, in which the asset price of a firm follows a double exponential jump diffusion process, the value of the debt is driven by a geometric Brownian motion, and the default barrier follows a continuous stochastic process. Using the Gaver-Stehfest algorithm and the non-arbitrage asset pricing theory, we give the default probability of the first passage time, and more, derive the price of the Credit Default Swap.展开更多
The dielectric properties of nucleated erythrocytes from bullfrogs were measured in a frequency range of 10 kHz–110 MHz.The complex permittivity(ε*),complex conductivity(κ*),and complex resistivity(ρ*)were analyze...The dielectric properties of nucleated erythrocytes from bullfrogs were measured in a frequency range of 10 kHz–110 MHz.The complex permittivity(ε*),complex conductivity(κ*),and complex resistivity(ρ*)were analyzed and compared in the 10.63%to 37.58%haematocrit(Hct)range.The relaxation behavior,the passive electrical properties,and the cellular structure parameters,including the cell membrane,the cytoplasm,the nuclear membrane,and the nucleoplasm of the nucleated erythrocyte suspensions were investigated.The method used is based on the binomial Cole–Cole equation and the double spherical-shell physical models.Upon the elimination of the electrode polarization effect,two definite relaxations related to the interfacial polarization are observed on low-and high-frequency dispersions.The permittivity values and the characteristic frequency values differ by one order of magnitude:the low-frequency relaxation increments[?ε1=(5.63±1.43)×103]and the characteristic frequency[fc1=(297.06±14.48)kHz]derived from the cell membrane,the high-frequency relaxation increments[?ε2=(5.21±1.20)×102]and the characteristic frequency[fc2=(3.73±0.06)MHz]derived from the dielectric response to the external electric field of the nuclear membrane,respectively.Moreover,the other core dielectric parameters,such as the relative permittivity of the cell membrane[εm=(7.57±0.38)]and the nuclear envelope[εne=(23.59±4.39)],the conductivity of the cytoplasm(hemoglobin,κHb=(0.50±0.13)S/m]and the nuclear endoplasm[κnp=(2.56±0.75)S/m],and the capacitance of the bilayer membranes[Cm:(0.84±0.04)μF/cm2],and Cne:(0.52±0.10)μF/cm2]were also accurately and reliably measured.This work presents a feasible method to evaluate the dielectric parameters and the cellular structure of the erythrocytes of bullfrogs.Moreover,it paves the way for new studies on the haematology of frogs and the detection of nucleated cells via dielectric impedance spectroscopy.展开更多
Extending the double Jaynes Cummings model to a more complicated case where the mode-mode competition is considered, we investigate the entanglement character of two isolated atoms by means of concurrence, and discuss...Extending the double Jaynes Cummings model to a more complicated case where the mode-mode competition is considered, we investigate the entanglement character of two isolated atoms by means of concurrence, and discuss the dependence of atom atom entanglement on the different initial state and the relative coupling strength between the atom and the corresponding cavity field. The results show that the amplitude and the period of the atom atom entanglement evolution can be controlled by the choice of initial state and relative coupling strength, respectively. We find that the phenomenon of entanglement sudden death (ESD) is sensitive to the initial conditions. The length of the time interval for zero entanglement depends not only on the initial degree of entanglement between two atoms but also on the relative coupling strength of atom field interaction. The ESD effect can be weakened by enhancing the mode-mode competition between the three- and single-photon processes.展开更多
In order to analyze the maximum power density error with different heat flux distribution parameter values for double ellipsoidal heat source model, a general expression of double ellipsoidal heat source model was der...In order to analyze the maximum power density error with different heat flux distribution parameter values for double ellipsoidal heat source model, a general expression of double ellipsoidal heat source model was derived .front Goldak double ellipsoidal heat source model, and the error of maximum power density was analyzed under this foundation. The calculation error of thermal cycling parameters caused by the maximum power density error was compared quantitatively by numerical simulation. The results show that for guarantee the accuracy of welding numerical simulation, it is better to introduce an error correction coefficient into the Goldak double ellipsoidal heat source model expression. And, heat flux distribution parameter should get higher value for the higher power density welding methods.展开更多
-In this paper, the maximum entropy spectral, the cross-spectral and the frequency response analyses are madeon the basis of the data of monthly mean sea levels at coastal stations in the Bohai Sea during 1965-1986. T...-In this paper, the maximum entropy spectral, the cross-spectral and the frequency response analyses are madeon the basis of the data of monthly mean sea levels at coastal stations in the Bohai Sea during 1965-1986. The results show that the annual fluctuations of the monthly mean sea levels in the Bohai Sea are the results of the coupling response of seasonal variations of the marine hydrometeorological factors. Furthermore, the regression prediction equation is obtained by using the double screening stepwise regression analysis method . Through the prediction test , it is proved that the obtained results are desirable.展开更多
The Lanzhou-Urumqi high-speed railway is an important part of the railway network connecting Gansu,Qinghai,and Xinjiang,and it is of far-reaching significance in facilitating China’s western development.An accessibil...The Lanzhou-Urumqi high-speed railway is an important part of the railway network connecting Gansu,Qinghai,and Xinjiang,and it is of far-reaching significance in facilitating China’s western development.An accessibility model and a double difference model were built to analyze the impact of the Lanzhou-Urumqi high-speed railway on regional accessibility and economic development of the areas along the line before(2012-2014)and after(2017-2019)its opening.The results show that the regional accessibility remains unchanged before and after the operation of this railway line.However,there is a spatial difference in improvement,that of central cities being better.The opening of the high-speed railway is conducive to driving the overall economic development of the region and promoting the comprehensive and coordinated development of regional economies.展开更多
In this paper, we present a magnetocardiogram (MCG) simulation study using the boundary element method (BEM) and based on the virtual heart model and the realistic human volume conductor model. The different contr...In this paper, we present a magnetocardiogram (MCG) simulation study using the boundary element method (BEM) and based on the virtual heart model and the realistic human volume conductor model. The different contributions of cardiac equivalent source models and volume conductor models to the MCG are deeply and comprehensively investigated. The single dipole source model, the multiple dipoles source model and the equivalent double layer (EDL) source model are analysed and compared with the cardiac equivalent source models. Meanwhile, the effect of the volume conductor model on the MCG combined with these cardiac equivalent sources is investigated. The simulation results demonstrate that the cardiac electrophysiological information will be partly missed when only the single dipole source is taken, while the EDL source is a good option for MCG simulation and the effect of the volume conductor is smallest for the EDL source. Therefore, the EDL source is suitable for the study of MCG forward and inverse problems, and more attention should be paid to it in future MCG studies.展开更多
This paper reports a double helix model of charge transfer in DNA molecule. The calculated results show that the transmission characteristics of DNA are not only related to the longitudinal transfer but also to the he...This paper reports a double helix model of charge transfer in DNA molecule. The calculated results show that the transmission characteristics of DNA are not only related to the longitudinal transfer but also to the helicity of molecule. It finds that there are four transmission bands centred at 0.92, 3.07, 7.75 and 8.87eV, also the width and intensity of bands corresponding to the helix direction are less than that of the longitudinal direction. With the increase of hopping energy, transmission bands become wide so that the transmission ability is enhanced.展开更多
Three kinds of mathematical models representing welding heat sources are presented. Among them, Gaussian model and double ellipsoidal model are used to analyze the thermal distributions with finite element method. At ...Three kinds of mathematical models representing welding heat sources are presented. Among them, Gaussian model and double ellipsoidal model are used to analyze the thermal distributions with finite element method. At the same time, this paper analyzed the influences of the heat source models, the latent heat and the welding parameters on the temperature distributions. The comparisons between the simulated results and the experiments show double ellipsoidal model is good for three-dimensional numerical simulations. Furthermore, the adaptive mesh technique is applied in the three-dimensional model which greatly reduces the number of nodes and elements in the simulation.展开更多
Three-dimensional seepage in double fractured media was modeled in this paper. The determination of hydraulic conductivity tensor of rock mass is a vital problem for the sea water intrusion or sea water encroachment a...Three-dimensional seepage in double fractured media was modeled in this paper. The determination of hydraulic conductivity tensor of rock mass is a vital problem for the sea water intrusion or sea water encroachment and seepage of fissured medium. According to the geological and hydrogeological conditions for the 2nd-stage construction of the Three Gorges Project (TGP), the physical and mathematical models for the groundwater movement through the 3D double fractured media of rock mass during construction were established in this paper. Based on discontinuity-control inverse theory, some related parameters of double fractured media were inversed with flux being the known quantity and calibration of water table the objective function. Synchronously, the seepage field of the construction region was systematically analyzed and simulated, the results of which exhibit that the double fractured media model of fracture water can comprehensively and correctly describe the geological and hydrogeological conditions in the construction region.展开更多
This study examines the impact of farmers’cooperatives participation and technology adoption on their economic welfare in China.A double selectivity model(DSM)is applied to correct for sample selection bias stemming ...This study examines the impact of farmers’cooperatives participation and technology adoption on their economic welfare in China.A double selectivity model(DSM)is applied to correct for sample selection bias stemming from both observed and unobserved factors,and a propensity score matching(PSM)method is applied to calculate the agricultural income difference with counter factual analysis using survey data from 396 farmers in 15 provinces in China.The findings indicate that farmers who join farmer cooperatives and adopt agricultural technology can increase agricultural income by 2.77 and 2.35%,respectively,compared with those non-participants and non-adopters.Interestingly,the effect on agricultural income is found to be more significant for the low-income farmers than the high-income ones,with income increasing 5.45 and 4.51%when participating in farmer cooperatives and adopting agricultural technology,respectively.Our findings highlight the positive role of farmer cooperatives and agricultural technology in promoting farmers’economic welfare.Based on the findings,government policy implications are also discussed.展开更多
The factors affecting the adoption of modern varieties(MVs) of rice and impact on poverty in Odisha, India were discussed. A total of 363 households from Cuttack and Sambalpur districts of Odisha via multistage sampli...The factors affecting the adoption of modern varieties(MVs) of rice and impact on poverty in Odisha, India were discussed. A total of 363 households from Cuttack and Sambalpur districts of Odisha via multistage sampling technique participated in the survey. The Cragg's Double hurdle model was used to model the determinants of adoption and intensity of adoption of MVs of rice, and the propensity score matching was used to analyze the impact of adoption on poverty. The results showed that age, education, risk aversion, land size, yield, perception of MVs as high yielding, resistant to diseases and availability of MVs positively influenced the decision to adopt. However, variables such as household size, experience of a farmer, off-farm job participation, amount of credit received, cost of seeds, insecticides and fertilizers negatively influenced the adoption of MVs. Intensity of adoption of MVs was negatively influenced by experience of a farmer, cost of fertilizer and marketability of MVs, and positively affected by household size, risk aversion, land size, cost of insecticides, perception of MVs as high yielding and availability of MV seeds. Poverty incidence, gap and severity were high among non-adopters to adopters of MVs. After matching adopters and non-adopters of MV groups using four different algorithms of nearest neighbour matching, stratification matching, radius matching and kernel matching, the impact of MV adoption resulted in higher per capita monthly household expenditure by about US$ 52.82 to US$ 63.17.展开更多
By considering a double Jaynes-Cummings model, we investigate the dynamics of quantum correlations, such as the quantum discord and the entanglement, for two atoms in their respective noisy environments, and study the...By considering a double Jaynes-Cummings model, we investigate the dynamics of quantum correlations, such as the quantum discord and the entanglement, for two atoms in their respective noisy environments, and study the effect of the purity and the cavity temperature on the quantum correlations. The results show that the entanglement suffers sudden death and revival, however the quantum discord can still reveal the quantum correlations between the two atoms in the region where the entanglement is zero. Moreover, when the temperature of each cavity is high the entanglement dies out in a short time, but the quantum discord still survives for quite a long time. It means that the quantum discord is more resistant to environmental disturbance than the entanglement at higher temperatures.展开更多
Semiparametric mixed-effects double regression models have been used for analysis of longitu-dinal data in a variety of applications,as they allow researchers to jointly model the mean and variance of the mixed-effect...Semiparametric mixed-effects double regression models have been used for analysis of longitu-dinal data in a variety of applications,as they allow researchers to jointly model the mean and variance of the mixed-effects as a function of predictors.However,these models are commonly estimated based on the normality assumption for the errors and the results may thus be sensitive to outliers and/or heavy-tailed data.Quantile regression is an ideal alternative to deal with these problems,as it is insensitive to heteroscedasticity and outliers and can make statistical analysis more robust.In this paper,we consider Bayesian quantile regression analysis for semiparamet-ric mixed-effects double regression models based on the asymmetric Laplace distribution for the errors.We construct a Bayesian hierarchical model and then develop an efficient Markov chain Monte Carlo sampling algorithm to generate posterior samples from the full posterior dis-tributions to conduct the posterior inference.The performance of the proposed procedure is evaluated through simulation studies and a real data application.展开更多
The interface adhesion strength(or interface toughness)of a thin film/substrate system is often assessed by the micro-scratch test.For a brittle film material,the interface adhesion strength is easily obtained through...The interface adhesion strength(or interface toughness)of a thin film/substrate system is often assessed by the micro-scratch test.For a brittle film material,the interface adhesion strength is easily obtained through measuring the scratch driving forces.However,to measure the interface adhesion strength(or in- terface toughness)for a metal thin film material(the ductile material)by the micro- scratch test is very difficult,because intense plastic deformation is involved and the problem is a three-dimensional elastic-plastic one.In the present research,using a double-cohesive zone model,the failure characteristics of the thin film/substrate system can be described and further simulated.For a steady-state scratching pro- cess,a three-dimensional elastic-plastic finite element method based on the double cohesive zone model is developed and adopted,and the steady-state fracture work of the total system is calculated.The parameter relations between the horizontal driving forces(or energy release rate of the scratching process)and the separation strength of thin film/substrate interface,and the material shear strength,as well as the material parameters are developed.Furthermore,a scratch experiment for the Al/Si film/substrate system is carried out and the failure mechanisms are explored. Finally,the prediction results are applied to a scratch experiment for the Pt/NiO material system given in the literature.展开更多
With the global warming and sea level rising, it is widely recognized that there is an increasing tendency of typhoon occurrence frequency and intensity. The defenses code against typhoon attacks for nuclear power pla...With the global warming and sea level rising, it is widely recognized that there is an increasing tendency of typhoon occurrence frequency and intensity. The defenses code against typhoon attacks for nuclear power plant should be calibrated because of the increasing threat of typhoon disaster and severe consequences. This paper discusses the probabilistic approach of definitions about "probable maximum typhoon" and "probable maximum storm surge" in nuclear safety regulations of China and has made some design code calibrations by use of a newly proposed Double Layer Nested Mtdti-objective Probability Model (DLNMPM).展开更多
基金The research was funded by National Natural Science Foundation (40231016) and Canadian International Development Agency (CIDA).
文摘The dynamics of soil organic carbon (SOC) was analyzed by using laboratory incubation and double exponential model that mineralizable SOC was separated into active carbon pools and slow carbon pools in forest soils derived from Changbai and Qilian Mountain areas. By analyzing and fitting the CO2 evolved rates with SOC mineralization, the results showed that active carbon pools accounted tor 1.0% to 8.5% of SOC with an average of mean resistant times (MRTs) for 24 days, and slow carbon pools accounted for 91% to 99% of SOC with an average of MRTs for 179 years. The sizes and MRTs of slow carbon pools showed that SOC in Qilian Mountain sites was more difficult to decompose than that in Changbai Mountain sites. By analyzing the effects of temperature, soil clay content and elevation on SOC mineralization, results indicated that mineralization of SOC was directly related to temperature and that content of accumulated SOC and size of slow carbon pools from Changbai Mountain and Qilian Mountain sites increased linearly with increasing clay content, respectively, which showed temperature and clay content could make greater effect on mineralization of SOC.
基金Project supported by the National Natural Science Foundation of China (Grant No 60572177)
文摘Nucleus-nucleus potentials are determined in the framework of double folding model for M3Y-Reid and M3Y- Paris effective nucleon-nucleon (NN) interactions. Both zero-range and finite-range exchange parts of NN interactions are considered in the folding procedure. In this paper the spherical projectile-spherical target system 16O+^2008Pb is selected for calculating the barrier energies, fusion cross sections and barrier distributions with the density-independent and density-dependent NN interactions on the basis of M3Y-Reid and M3Y Paris NN interactions. The barrier energies become lower for Paris NN interactions in comparison with Reid NN interactions, and also for finite-range exchange part in comparison with zero-range exchange part. The density-dependent NN interactions give similar fusion cross sections and barrier distributions, and the density-independent NN interaction causes the barrier distribution moving to a higher position. However, the density-independent Reid NN interaction with zero-range exchange part gives the lowest fusion cross sections. We find that the calculated fusion cross sections and the barrier distributions are in agreement with the experimental data after renormalization of the nuclear potential due to coupled-channel effect.
文摘This research appraises comparative analysis between single diode and double diode model of photovoltaic (PV) solar cells to enhance the conversion efficiency of power engendering PV solar systems. Single diode model is simple and easy to implement, whereas double diode model has better accuracy which acquiesces for more precise forecast of PV systems performance. Exploration is done on the basis of simulation results and MATLAB tool is used to serve this purpose. Simulations are performed by varying distinct model parameters such as solar irradiance, temperature, value of parasitic resistances, ideality factor of diode and number of series and parallel connected solar cells used to assemble PV array. Conspicuous demonstration is executed to analyze effects of these specifications on the efficiency curve and power vs. voltage output characteristics of PV cell for specified models.
基金Supported by The National Natural Science Foundation of China(71261015)Humanity and Social Science Youth Foundation of Education Ministry in China(10YJC630334)Program for Innovative Research Team in Universities of Inner Mongolia Autonomous Region
文摘This paper discusses the valuation of the Credit Default Swap based on a jump market, in which the asset price of a firm follows a double exponential jump diffusion process, the value of the debt is driven by a geometric Brownian motion, and the default barrier follows a continuous stochastic process. Using the Gaver-Stehfest algorithm and the non-arbitrage asset pricing theory, we give the default probability of the first passage time, and more, derive the price of the Credit Default Swap.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51277099 and 52007087)the Natural Science Foundation of Zhejiang Province,China(Grant Nos.LY20C110001 and LSY19A010002)+2 种基金the Natural Science Foundation of Ningbo City,China(Grant Nos.2019A610349 and 202003N4116)the Fund from the Educational Commission of Zhejiang Province,China(Grant No.Y202044047)the Fundamental Research Funds for the Provincial Universities of Zhejiang Province,China.
文摘The dielectric properties of nucleated erythrocytes from bullfrogs were measured in a frequency range of 10 kHz–110 MHz.The complex permittivity(ε*),complex conductivity(κ*),and complex resistivity(ρ*)were analyzed and compared in the 10.63%to 37.58%haematocrit(Hct)range.The relaxation behavior,the passive electrical properties,and the cellular structure parameters,including the cell membrane,the cytoplasm,the nuclear membrane,and the nucleoplasm of the nucleated erythrocyte suspensions were investigated.The method used is based on the binomial Cole–Cole equation and the double spherical-shell physical models.Upon the elimination of the electrode polarization effect,two definite relaxations related to the interfacial polarization are observed on low-and high-frequency dispersions.The permittivity values and the characteristic frequency values differ by one order of magnitude:the low-frequency relaxation increments[?ε1=(5.63±1.43)×103]and the characteristic frequency[fc1=(297.06±14.48)kHz]derived from the cell membrane,the high-frequency relaxation increments[?ε2=(5.21±1.20)×102]and the characteristic frequency[fc2=(3.73±0.06)MHz]derived from the dielectric response to the external electric field of the nuclear membrane,respectively.Moreover,the other core dielectric parameters,such as the relative permittivity of the cell membrane[εm=(7.57±0.38)]and the nuclear envelope[εne=(23.59±4.39)],the conductivity of the cytoplasm(hemoglobin,κHb=(0.50±0.13)S/m]and the nuclear endoplasm[κnp=(2.56±0.75)S/m],and the capacitance of the bilayer membranes[Cm:(0.84±0.04)μF/cm2],and Cne:(0.52±0.10)μF/cm2]were also accurately and reliably measured.This work presents a feasible method to evaluate the dielectric parameters and the cellular structure of the erythrocytes of bullfrogs.Moreover,it paves the way for new studies on the haematology of frogs and the detection of nucleated cells via dielectric impedance spectroscopy.
基金Project supported by the National Natural Science Foundation of China (Grant No 10374025)the Foundation of Education Department of Hunan Province of China (Grant Nos 06A038 and 06C080)the Science and Technology Project of Zhanjiang City (Grant No 2008C10019)
文摘Extending the double Jaynes Cummings model to a more complicated case where the mode-mode competition is considered, we investigate the entanglement character of two isolated atoms by means of concurrence, and discuss the dependence of atom atom entanglement on the different initial state and the relative coupling strength between the atom and the corresponding cavity field. The results show that the amplitude and the period of the atom atom entanglement evolution can be controlled by the choice of initial state and relative coupling strength, respectively. We find that the phenomenon of entanglement sudden death (ESD) is sensitive to the initial conditions. The length of the time interval for zero entanglement depends not only on the initial degree of entanglement between two atoms but also on the relative coupling strength of atom field interaction. The ESD effect can be weakened by enhancing the mode-mode competition between the three- and single-photon processes.
文摘In order to analyze the maximum power density error with different heat flux distribution parameter values for double ellipsoidal heat source model, a general expression of double ellipsoidal heat source model was derived .front Goldak double ellipsoidal heat source model, and the error of maximum power density was analyzed under this foundation. The calculation error of thermal cycling parameters caused by the maximum power density error was compared quantitatively by numerical simulation. The results show that for guarantee the accuracy of welding numerical simulation, it is better to introduce an error correction coefficient into the Goldak double ellipsoidal heat source model expression. And, heat flux distribution parameter should get higher value for the higher power density welding methods.
文摘-In this paper, the maximum entropy spectral, the cross-spectral and the frequency response analyses are madeon the basis of the data of monthly mean sea levels at coastal stations in the Bohai Sea during 1965-1986. The results show that the annual fluctuations of the monthly mean sea levels in the Bohai Sea are the results of the coupling response of seasonal variations of the marine hydrometeorological factors. Furthermore, the regression prediction equation is obtained by using the double screening stepwise regression analysis method . Through the prediction test , it is proved that the obtained results are desirable.
文摘The Lanzhou-Urumqi high-speed railway is an important part of the railway network connecting Gansu,Qinghai,and Xinjiang,and it is of far-reaching significance in facilitating China’s western development.An accessibility model and a double difference model were built to analyze the impact of the Lanzhou-Urumqi high-speed railway on regional accessibility and economic development of the areas along the line before(2012-2014)and after(2017-2019)its opening.The results show that the regional accessibility remains unchanged before and after the operation of this railway line.However,there is a spatial difference in improvement,that of central cities being better.The opening of the high-speed railway is conducive to driving the overall economic development of the region and promoting the comprehensive and coordinated development of regional economies.
基金supported by the State Key Development Program for Basic Research of China (Grant Nos. 2007CB512100 and2006CB601007)the National Natural Science Foundation of China (Grant No. 10674006)+2 种基金the National High Technology Research and Development Program of China (Grant No. 2007AA03Z238)China Postdoctoral Science Foundation (Grant No. 20090461376)the Fundamental Research Funds for the Central Universities (Grant No. KYJD09001)
文摘In this paper, we present a magnetocardiogram (MCG) simulation study using the boundary element method (BEM) and based on the virtual heart model and the realistic human volume conductor model. The different contributions of cardiac equivalent source models and volume conductor models to the MCG are deeply and comprehensively investigated. The single dipole source model, the multiple dipoles source model and the equivalent double layer (EDL) source model are analysed and compared with the cardiac equivalent source models. Meanwhile, the effect of the volume conductor model on the MCG combined with these cardiac equivalent sources is investigated. The simulation results demonstrate that the cardiac electrophysiological information will be partly missed when only the single dipole source is taken, while the EDL source is a good option for MCG simulation and the effect of the volume conductor is smallest for the EDL source. Therefore, the EDL source is suitable for the study of MCG forward and inverse problems, and more attention should be paid to it in future MCG studies.
基金Project supported by the National Natural Science Foundation of China (Grant No 60571062) and the Natural Science Foundation of Shandong Province, China (Grant No Y2004G09).
文摘This paper reports a double helix model of charge transfer in DNA molecule. The calculated results show that the transmission characteristics of DNA are not only related to the longitudinal transfer but also to the helicity of molecule. It finds that there are four transmission bands centred at 0.92, 3.07, 7.75 and 8.87eV, also the width and intensity of bands corresponding to the helix direction are less than that of the longitudinal direction. With the increase of hopping energy, transmission bands become wide so that the transmission ability is enhanced.
文摘Three kinds of mathematical models representing welding heat sources are presented. Among them, Gaussian model and double ellipsoidal model are used to analyze the thermal distributions with finite element method. At the same time, this paper analyzed the influences of the heat source models, the latent heat and the welding parameters on the temperature distributions. The comparisons between the simulated results and the experiments show double ellipsoidal model is good for three-dimensional numerical simulations. Furthermore, the adaptive mesh technique is applied in the three-dimensional model which greatly reduces the number of nodes and elements in the simulation.
基金the National Natural Science Foundation of China (Grant Nos: 50179010 and 50239070)
文摘Three-dimensional seepage in double fractured media was modeled in this paper. The determination of hydraulic conductivity tensor of rock mass is a vital problem for the sea water intrusion or sea water encroachment and seepage of fissured medium. According to the geological and hydrogeological conditions for the 2nd-stage construction of the Three Gorges Project (TGP), the physical and mathematical models for the groundwater movement through the 3D double fractured media of rock mass during construction were established in this paper. Based on discontinuity-control inverse theory, some related parameters of double fractured media were inversed with flux being the known quantity and calibration of water table the objective function. Synchronously, the seepage field of the construction region was systematically analyzed and simulated, the results of which exhibit that the double fractured media model of fracture water can comprehensively and correctly describe the geological and hydrogeological conditions in the construction region.
基金the Special Project of Major Theoretical Research and Interpretation of Philosophy and Social Sciences of Chongqing Municipal Education Commission,China(19SKZDZX15)the Key Project of Humanities and Social Sciences Research of Chongqing Education Commission,China(18SKSJ003)the Funding for Cultivating Major Projects in Humanities and Social Sciences of Southwest University,China(SWU1809009)。
文摘This study examines the impact of farmers’cooperatives participation and technology adoption on their economic welfare in China.A double selectivity model(DSM)is applied to correct for sample selection bias stemming from both observed and unobserved factors,and a propensity score matching(PSM)method is applied to calculate the agricultural income difference with counter factual analysis using survey data from 396 farmers in 15 provinces in China.The findings indicate that farmers who join farmer cooperatives and adopt agricultural technology can increase agricultural income by 2.77 and 2.35%,respectively,compared with those non-participants and non-adopters.Interestingly,the effect on agricultural income is found to be more significant for the low-income farmers than the high-income ones,with income increasing 5.45 and 4.51%when participating in farmer cooperatives and adopting agricultural technology,respectively.Our findings highlight the positive role of farmer cooperatives and agricultural technology in promoting farmers’economic welfare.Based on the findings,government policy implications are also discussed.
基金supported by Federation of Indian Chambers of Commerce & Industry (2017–2018) through the Government of India under CV Raman Post-Doctoral Fellowship for African Researchers
文摘The factors affecting the adoption of modern varieties(MVs) of rice and impact on poverty in Odisha, India were discussed. A total of 363 households from Cuttack and Sambalpur districts of Odisha via multistage sampling technique participated in the survey. The Cragg's Double hurdle model was used to model the determinants of adoption and intensity of adoption of MVs of rice, and the propensity score matching was used to analyze the impact of adoption on poverty. The results showed that age, education, risk aversion, land size, yield, perception of MVs as high yielding, resistant to diseases and availability of MVs positively influenced the decision to adopt. However, variables such as household size, experience of a farmer, off-farm job participation, amount of credit received, cost of seeds, insecticides and fertilizers negatively influenced the adoption of MVs. Intensity of adoption of MVs was negatively influenced by experience of a farmer, cost of fertilizer and marketability of MVs, and positively affected by household size, risk aversion, land size, cost of insecticides, perception of MVs as high yielding and availability of MV seeds. Poverty incidence, gap and severity were high among non-adopters to adopters of MVs. After matching adopters and non-adopters of MV groups using four different algorithms of nearest neighbour matching, stratification matching, radius matching and kernel matching, the impact of MV adoption resulted in higher per capita monthly household expenditure by about US$ 52.82 to US$ 63.17.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.60978011 and 10905028)the Program for Science and Technology Department of Henan Province,China(Grant No.102300410050)the Cultivation Fund of Luoyang Normal College,China
文摘By considering a double Jaynes-Cummings model, we investigate the dynamics of quantum correlations, such as the quantum discord and the entanglement, for two atoms in their respective noisy environments, and study the effect of the purity and the cavity temperature on the quantum correlations. The results show that the entanglement suffers sudden death and revival, however the quantum discord can still reveal the quantum correlations between the two atoms in the region where the entanglement is zero. Moreover, when the temperature of each cavity is high the entanglement dies out in a short time, but the quantum discord still survives for quite a long time. It means that the quantum discord is more resistant to environmental disturbance than the entanglement at higher temperatures.
基金Dr.Wu was supported by the National Natural Science Foundation of China under grant 11861041Drs.Keying Ye and Min Wang were partially supported by a grant from the UTSA Vice President for Research,Economic Development,and Knowledge Enterprise at the University of Texas at San Antonio.
文摘Semiparametric mixed-effects double regression models have been used for analysis of longitu-dinal data in a variety of applications,as they allow researchers to jointly model the mean and variance of the mixed-effects as a function of predictors.However,these models are commonly estimated based on the normality assumption for the errors and the results may thus be sensitive to outliers and/or heavy-tailed data.Quantile regression is an ideal alternative to deal with these problems,as it is insensitive to heteroscedasticity and outliers and can make statistical analysis more robust.In this paper,we consider Bayesian quantile regression analysis for semiparamet-ric mixed-effects double regression models based on the asymmetric Laplace distribution for the errors.We construct a Bayesian hierarchical model and then develop an efficient Markov chain Monte Carlo sampling algorithm to generate posterior samples from the full posterior dis-tributions to conduct the posterior inference.The performance of the proposed procedure is evaluated through simulation studies and a real data application.
基金The project supported by the National Natural Science Foundation of China (19891180 and 19925211)Bai Ren Plan of CAS
文摘The interface adhesion strength(or interface toughness)of a thin film/substrate system is often assessed by the micro-scratch test.For a brittle film material,the interface adhesion strength is easily obtained through measuring the scratch driving forces.However,to measure the interface adhesion strength(or in- terface toughness)for a metal thin film material(the ductile material)by the micro- scratch test is very difficult,because intense plastic deformation is involved and the problem is a three-dimensional elastic-plastic one.In the present research,using a double-cohesive zone model,the failure characteristics of the thin film/substrate system can be described and further simulated.For a steady-state scratching pro- cess,a three-dimensional elastic-plastic finite element method based on the double cohesive zone model is developed and adopted,and the steady-state fracture work of the total system is calculated.The parameter relations between the horizontal driving forces(or energy release rate of the scratching process)and the separation strength of thin film/substrate interface,and the material shear strength,as well as the material parameters are developed.Furthermore,a scratch experiment for the Al/Si film/substrate system is carried out and the failure mechanisms are explored. Finally,the prediction results are applied to a scratch experiment for the Pt/NiO material system given in the literature.
基金supported by the Nationam Natural Science Foundation of China(Grant No.50679076)Office of State Flood Control and Drought Relief Headquarters of China(Grant No.20060120)
文摘With the global warming and sea level rising, it is widely recognized that there is an increasing tendency of typhoon occurrence frequency and intensity. The defenses code against typhoon attacks for nuclear power plant should be calibrated because of the increasing threat of typhoon disaster and severe consequences. This paper discusses the probabilistic approach of definitions about "probable maximum typhoon" and "probable maximum storm surge" in nuclear safety regulations of China and has made some design code calibrations by use of a newly proposed Double Layer Nested Mtdti-objective Probability Model (DLNMPM).