The present article provides supplementary information of previous works of analytic models for predicting conductivity enhancements of carbon nanotube composites. The models, though fairly simple, are able to take ac...The present article provides supplementary information of previous works of analytic models for predicting conductivity enhancements of carbon nanotube composites. The models, though fairly simple, are able to take account of the effects of conductivity anisotropy, nonstraightness, and aspect ratio of the CNT additives on the conductivity enhancement of the composite and to give predictions agreeing well with existing experimental data. The omitted detailed derivation of this model is demonstrated in the present article with a more systematical analysis, which may help with further development in this direction. Furthermore, the effects of various orientation distributions of CNTs are reported here for the first time. The information may be useful in design or fabrication technology of CNT composites for better or specified conductivities.展开更多
Physical mechanisms and influencing factors on the effective stress coefficient for rock/soil-like porous materials are investigated, based on which equivalent connectivity index is proposed. The equivalent connectivi...Physical mechanisms and influencing factors on the effective stress coefficient for rock/soil-like porous materials are investigated, based on which equivalent connectivity index is proposed. The equivalent connectivity index, relying on the meso-scale structure of porous material and the property of liquid, denotes the connectivity of pores in Representative Element Area (REA). If the conductivity of the porous material is anisotropic, the equivalent connectivity index is a second order tensor. Based on the basic theories of continuous mechanics and tensor analysis, relationship between area porosity and volumetric porosity of porous materials is deduced. Then a generalized expression, describing the relation between effective stress coefficient tensor and equivalent connectivity tensor of pores, is proposed, and the expression can be applied to isotropic media and also to anisotropic materials. Furthermore, evolution of porosity and equivalent connectivity index of the pore are studied in the strain space, and the method to determine the corresponding functions in expressions above is proposed using genetic algorithm and genetic programming. Two applications show that the results obtained by the method in this paper perfectly agree with the test data. This paper provides an important theoretical support to the coupled hydro-mechanical research.展开更多
CNMC combines social responsibility with corporate vision as it expands in Africa TODAY non-ferrous metals(metals other than iron and alloys that do not contain an appreciable amount of iron) are an indispensable par...CNMC combines social responsibility with corporate vision as it expands in Africa TODAY non-ferrous metals(metals other than iron and alloys that do not contain an appreciable amount of iron) are an indispensable part of every aspect of our lives. From daily necessities like telephones and electric cookers,to sophisticated equipment like satellites and radar,non-ferrous展开更多
Over the past few decades,the Internet has rapidly diffused across China.The spread of the Internet has had a profound economic and social impact on Chinese rural areas.Existing research shows that Internet access sig...Over the past few decades,the Internet has rapidly diffused across China.The spread of the Internet has had a profound economic and social impact on Chinese rural areas.Existing research shows that Internet access significantly impacts agricultural production and improves smallholder farmers’income.Beyond these,the Internet can affect other dimensions of social welfare.However,research about the impact of Internet access on dietary quality in rural China remains scarce.This study utilizes multi-period panel data from Fixed Observation Point in rural China from 2009 to 2015 to estimate the impact of Internet access on dietary quality and food consumption of rural households and conducts a causal analysis.Regression models with time and household fixed effects allow robust estimation while reducing potential issues of unobserved heterogeneity.The estimates show that Internet access has significantly increased rural household dietary quality(measured by the Chinese Diet Balance Index).Further research finds that Internet access has increased the consumption of animal products,such as aquatic and dairy products.We also examine the underlying mechanisms.Internet access improves dietary quality and food consumption mainly through increasing household income and food expenditure.These results encourage the promotion of Internet access as a valuable tool for nutritional improvements,especially in rural areas.展开更多
When a gas-liquid two-phase flow(GLTPF)enters a parallel separator through a T-junction,it generally splits unevenly.This phenomenon can seriously affect the operation efficiency and safety of the equipment located do...When a gas-liquid two-phase flow(GLTPF)enters a parallel separator through a T-junction,it generally splits unevenly.This phenomenon can seriously affect the operation efficiency and safety of the equipment located downstream.In order to investigate these aspects and,more specifically,the so-called bias phenomenon(all gas and liquid flowing to one pipe,while the other pipe is a liquid column that fluctuates up and down),laboratory experiments were carried out by using a T-junction connected to two parallel vertical pipes.Moreover,a GLTPF prediction model based on the principle of minimum potential energy was introduced.The research results indicate that this model can accurately predict the GLTPF state in parallel risers.The boundary of the slug flow and the churn flow in the opposite pipe can be predicted.Overall,according to the results,the pressure drop curves of the two-phase flow in the parallel risers are basically the same when there is no bias phenomenon,but the pressure drop in the parallel riser displays a large deviation when there is a slug flow-churn flow.Only when the parallel riser is in a state of asymmetric flow and one of the risers produces churn flow,the two-phase flow is prone to produce the bias phenomenon.展开更多
The effective liquid drop model(ELDM)is improved by introducing an accurate nuclear charge radius formula and an analytic expression for assaulting frequency.Within the improved effective liquid drop model(IMELDM),the...The effective liquid drop model(ELDM)is improved by introducing an accurate nuclear charge radius formula and an analytic expression for assaulting frequency.Within the improved effective liquid drop model(IMELDM),the experimental cluster radioactivity half-lives of the trans-lead region are calculated.It is shown that the accuracy of the IMELDM is improved compared with that of the ELDM.At last,the cluster radioactivity half-lives that are experimentally unavailable for the trans-lead nuclei are predicted by the IMELDM.These predictions may be useful for searching for new candidates for cluster radioactivity in future experiments.展开更多
The digital economy,as a new emerging economic form,has become an important power for realizing Chinese-style modernization and promoting green development in China.This paper measures the digital economy and low-carb...The digital economy,as a new emerging economic form,has become an important power for realizing Chinese-style modernization and promoting green development in China.This paper measures the digital economy and low-carbon transition index based on the data of 30 provinces in China from 2013 to 2020 and analyzes the mechanism and path of the digital economy affecting low-carbon transition using the fixed effect panel data model and the threshold effect model.It is found that,(1)The digital economy and low-carbon transition in China are various in different regions,with characteristics of being unbalanced and insufficient.(2)The digital economy significantly promotes low-carbon transition,with the greatest influence in the Central region,followed by the Eastern region and the Western region.Under different dimensions,the development of informatization and digital transactions promote low-carbon transition,but the development of the internet plays an inhibiting role.(3)The higher the degree of urbanization and environmental regulation,the greater the influence of the digital economy on low-carbon transition.展开更多
Bayes decision rule of variance components for one-way random effects model is derived and empirical Bayes (EB) decision rules are constructed by kernel estimation method. Under suitable conditions, it is shown that t...Bayes decision rule of variance components for one-way random effects model is derived and empirical Bayes (EB) decision rules are constructed by kernel estimation method. Under suitable conditions, it is shown that the proposed EB decision rules are asymptotically optimal with convergence rates near O(n-1/2). Finally, an example concerning the main result is given.展开更多
A modelling study is performed to compare the plasma flow and heat transfer characteristics of low-power arc-heated thrusters (arcjets) for three different propellants: hydrogen, nitrogen and argon. The all-speed S...A modelling study is performed to compare the plasma flow and heat transfer characteristics of low-power arc-heated thrusters (arcjets) for three different propellants: hydrogen, nitrogen and argon. The all-speed SIMPLE algorithm is employed to solve the governing equations, which take into account the effects of compressibility, Lorentz force and Joule heating, as well as the temperature- and pressure-dependence of the gas properties. The temperature, velocity and Mach number distributions calculated within the thruster nozzle obtained with different propellant gases are compared for the same thruster structure, dimensions, inlet-gas stagnant pressure and arc currents. The temperature distributions in the solid region of the anode-nozzle wall are also given. It is found that the flow and energy conversion processes in the thruster nozzle show many similar features for all three propellants. For example, the propellant is heated mainly in the near-cathode and constrictor region, with the highest plasma temperature appearing near the cathode tip; the flow transition from the subsonic to supersonic regime occurs within the constrictor region; the highest axial velocity appears inside the nozzle; and most of the input propellant flows towards the thruster exit through the cooler gas region near the anode-nozzle wall. However, since the properties of hydrogen, nitrogen and argon, especially their molecular weights, specific enthMpies and thermal conductivities, are different, there are appreciable differences in arcjet performance. For example, compared to the other two propellants, the hydrogen arcjet thruster shows a higher plasma temperature in the arc region, and higher axial velocity but lower temperature at the thruster exit. Correspondingly, the hydrogen arcjet thruster has the highest specific impulse and arc voltage for the same inlet stagnant pressure and arc current. The predictions of the modelling are compared favourably with available experimental results.展开更多
In the present investigations, the antitumorigenic effect of black tea polyphenols (BTP) in twcrstage mouse skin model of carcinogenesis was studied. The animals were initiated with a single 'subcarcinogenic' ...In the present investigations, the antitumorigenic effect of black tea polyphenols (BTP) in twcrstage mouse skin model of carcinogenesis was studied. The animals were initiated with a single 'subcarcinogenic' topical dose (52 μg/200 μl acetone ) of 7, 12-dimethylbenzanthracene (DMBA). To evaluate the anti-tumour initiating activity, BTP was topically applied twice a week for three weeks prior to DMBA application, followed by topical treatment with 12-o-tetradecanoyl phorbol-13-acetate (TPA) (5 μg/200 μl acetone, 2x/wk. ) as promoter. For evaluation of antitumor promoting activity, BTP was applied prior to each treatment of TPA. BTP application showed marked inhibitory effect as antitumour initiator as well as antitumour promoter in mouse skin medel of two-stage carcinogenesis. Since initiation involves genetic pathway and tumour promotion involves epigenetic pathway, it seems that BTP exerts its antitumorigenic effect by altering both genetic and epigenetic pathways展开更多
Fetr6 is an underground mine in which chromite is extracted using stope and pillar mining method. Despite of all improving works such as roof supporting and replacing of ore pillars with concrete pillars, pillar No. 1...Fetr6 is an underground mine in which chromite is extracted using stope and pillar mining method. Despite of all improving works such as roof supporting and replacing of ore pillars with concrete pillars, pillar No. 19 failed and other pillars failed progressively as a domino effect and 4000 m2 of mine collapsed within a few minutes, consequently. For detail investigation, two 3-D numerical models were developed by 3Dec. The first, a base model, was used for estimation of stress on pillars just before failure and the other for investigation of rock burst in pillar No. 19. The results show that discontinuity parameters such as friction angle and shear stiffness is critical parameters in this pillar failure. In addition, it indicates that W/H ratio equal 0.3, the lack of ore extraction strategy and inadequate roof support are the major reasons for this failure. In this paper, the procedure of study was described.展开更多
Due to the large quasi-piezoelectric d33 coefficient in the film thickness direction, cellular piezoelectret has emerged as a new kind of compliant electromechanical transducer materials. The macroscopic piezoelectric...Due to the large quasi-piezoelectric d33 coefficient in the film thickness direction, cellular piezoelectret has emerged as a new kind of compliant electromechanical transducer materials. The macroscopic piezoelectric effect of cellular piezoelectret is closely related to the void microstructures as well as the material constants of host polymer. Complex void microstmctures are usually encountered in the optimum design of cellular piezoelectret polymer film with ad- vanced piezoelectric properties. Analysis of the effective electromechanical properties is generally needed. This article presents an overview of the recent progress on theoretical models and numerical simulation for the effective electromechanical properties of cellular piezoelectret. Emphasis is placed on our own works of cellular piezoelectret published in past several years.展开更多
The effects of three different typical resistivity models(Spitzer, Z&L and M&G) on the performance of pulsed inductive acceleration plasma are studied. Numerical results show that their influences decrease with th...The effects of three different typical resistivity models(Spitzer, Z&L and M&G) on the performance of pulsed inductive acceleration plasma are studied. Numerical results show that their influences decrease with the increase of the plasma temperature. The significant discriminations among them appear at the plasma temperature lower than 2.5 eV, and the maximum gap of the pulsed inductive plasma accelerated efficiency is approximately 2.5%.Moreover, the pulsed inductive plasma accelerated efficiency is absolutely related to the dynamic impedance parameters, such as voltage, inductance, capacitance and flow rate. However, the distribution of the efficiency as a function of plasma temperature with three resistivity models has nothing to do with the dynamic impedance parameter.展开更多
Submarine landslides can cause severe damage to marine engineering structures. Their sliding velocity and runout distance are two major parameters for quantifying and analyzing the risk of submarine landslides.Current...Submarine landslides can cause severe damage to marine engineering structures. Their sliding velocity and runout distance are two major parameters for quantifying and analyzing the risk of submarine landslides.Currently, commercial calculation programs such as BING have limitations in simulating underwater soil movements. All of these processes can be consistently simulated through a smoothed particle hydrodynamics(SPH) depth integrated model. The basis of the model is a control equation that was developed to take into account the effects of soil consolidation and erosion. In this work, the frictional rheological mode has been used to perform a simulation study of submarine landslides. Time-history curves of the sliding body's velocity, height,and length under various conditions of water depth, slope gradient, contact friction coefficient, and erosion rate are compared; the maximum sliding distance and velocity are calculated; and patterns of variation are discussed.The findings of this study can provide a reference for disaster warnings and pipeline route selection.展开更多
In this paper,we consider the statistical inference problems for the fixed effect and variance component functions in the two-way classification random effects model with skewnormal errors.Firstly,the exact test stati...In this paper,we consider the statistical inference problems for the fixed effect and variance component functions in the two-way classification random effects model with skewnormal errors.Firstly,the exact test statistic for the fixed effect is constructed.Secondly,using the Bootstrap approach and generalized approach,the one-sided hypothesis testing and interval estimation problems for the single variance component,the sum and ratio of variance components are discussed respectively.Further,the Monte Carlo simulation results indicate that the exact test statistic performs well in the one-sided hypothesis testing problem for the fixed effect.And the Bootstrap approach is better than the generalized approach in the one-sided hypothesis testing problems for variance component functions in most cases.Finally,the above approaches are applied to the real data examples of the consumer price index and value-added index of three industries to verify their rationality and effectiveness.展开更多
It is well known that spline smoothing estimator relates to the Bayesian estimate under partially informative normal prior. In this paper, we derive the conditions for the pro- priety of the posterior in the nonparame...It is well known that spline smoothing estimator relates to the Bayesian estimate under partially informative normal prior. In this paper, we derive the conditions for the pro- priety of the posterior in the nonparametric mixed effects model under this class of partially informative normal prior for fixed effect with inverse gamma priors on the variance compo- nents and hierarchical priors for covariance matrix of random effect, then we explore the Gibbs sampling procedure.展开更多
We present a comprehensive numerical framework for the electrical and optical modeling and simulation of hybrid quantum dot light-emitting diodes(QD-LEDs).We propose a model known as hopping mobility to calculate the ...We present a comprehensive numerical framework for the electrical and optical modeling and simulation of hybrid quantum dot light-emitting diodes(QD-LEDs).We propose a model known as hopping mobility to calculate the carrier mobility in the emissive organic layer doped with quantum dots(QDs).To evaluate the ability of this model to describe the electrical characteristics of QD-LEDs,the measured data of a fabricated QD-LED with different concentrations of QDs in the emissive layer were taken,and the corresponding calculations were performed based on the proposed model.The simulation results indicate that the hopping mobility model can describe the concentration dependence of the electrical behavior of the device.Then,based on the continuity equation for singlet and triplet excitons,the exciton density profiles of the devices with different QD concentrations were extracted.Subsequently,the corresponding luminance characteristics of the devices were calculated,where the results are in good agreement with the experimental data.展开更多
By use of self-consistent field Xα scattered-wave (SCF-Xα-SW) method, the electronic structure was calculated for four models of Ti4Al14X (X=Al, Fe, Ni and Cu) clusters. The Ti4Al14X cluster was developed based on L...By use of self-consistent field Xα scattered-wave (SCF-Xα-SW) method, the electronic structure was calculated for four models of Ti4Al14X (X=Al, Fe, Ni and Cu) clusters. The Ti4Al14X cluster was developed based on L12 Al3Ti-base intermetallic compound. The results are presented using the density of states (DOS) and one-electron properties, such as relative binding tendency between the atom and the model cluster, and hybrid bonding tendency between the alloying element and the host atoms. By comparing the four models of Ti4Al14X cluster, the effect of the Fe, Ni or Cu atom on the physical properties of Al3Ti-based L12 intermetallic compounds is analyzed. The results indicate that the addition of the Fe, Ni or Cu atom intensifies the relative binding tendency between Ti atom and Ti4Al14X cluster. It was found that the Fermi level (EF) lies in a maximum in the DOS for Ti4Al14Al cluster; on the contrary, the EF comes near a minimum tn the DOS for Ti4Al14X (X=Fe, Ni and Cu) cluster. Thus the L12 crystal structure for binary Al3Ti alloy is unstable, and the addition of the Fe, Ni or Cu atom to Al3Ti is benefical to stabilize L12 crystal structure. The calculation also shows that the Fe, Ni or Cu atom strengthens the hybrid bonding tendency between the central atom and the host atoms for Ti4Al14X cluster and thereby may lead to the constriction of the lattice of Al3Ti-base intermetallic compounds.展开更多
The behavior of argon plasma driven by nanosecond pulsed plasma in a low-pressure plasma reactor is investigated using a global model, and the results are compared with the experimental measurements. The time evolutio...The behavior of argon plasma driven by nanosecond pulsed plasma in a low-pressure plasma reactor is investigated using a global model, and the results are compared with the experimental measurements. The time evolution of plasma density and the electron energy probability function are calculated by solving the energy balance and Boltzmann equations. During and shortly after the discharge pulse, the electron energy probability function can be represented by a bi-Maxwellian distribution, indicating two energy groups of electrons. According to the effective electron temperature calculation, we find that there are more high-energy electrons that play an important role in the excitation and ionization processes than low-energy electrons. The effective electron temperature is also measured via optical emission spectroscopy to evaluate the simulation model. In the comparison, the simulation results are found to be in agreement with the measure- ments. Furthermore, variations of the effective electron temperature are presented versus other discharge parameters, such as pulse width time, pulse rise time and gas pressure.展开更多
The prophylactic effects of Chinese propolis against cypermethrin toxicity were evaluated by performing ovary and uterus histopathology, as well as by characterizing ovarian function, embryos, and litters. Cypermethri...The prophylactic effects of Chinese propolis against cypermethrin toxicity were evaluated by performing ovary and uterus histopathology, as well as by characterizing ovarian function, embryos, and litters. Cypermethrin induced atypia in the ovary and uterus, and decreased the ovulation sites and the number of embryos. Cypermethrin-induced oxidative stress during pregnancy, decreased the parturition rate as well as the number and weight of offspring and increased the incidence of morphological malformations in the offspring. Administration of propolis to cypermethrin-treated animals mitigated cypermethrin-induced reproductive toxicity.展开更多
文摘The present article provides supplementary information of previous works of analytic models for predicting conductivity enhancements of carbon nanotube composites. The models, though fairly simple, are able to take account of the effects of conductivity anisotropy, nonstraightness, and aspect ratio of the CNT additives on the conductivity enhancement of the composite and to give predictions agreeing well with existing experimental data. The omitted detailed derivation of this model is demonstrated in the present article with a more systematical analysis, which may help with further development in this direction. Furthermore, the effects of various orientation distributions of CNTs are reported here for the first time. The information may be useful in design or fabrication technology of CNT composites for better or specified conductivities.
基金supported by the Yalongjiang River Joint Fund by the National Natural Science Foundation of China(NSFC)Ertan Hydropower Development Company,LTD(Nos.50579091 and 50539090)+1 种基金NSFC(No.10772190)Major State Basic Research Project of China(No.2002CB412708)
文摘Physical mechanisms and influencing factors on the effective stress coefficient for rock/soil-like porous materials are investigated, based on which equivalent connectivity index is proposed. The equivalent connectivity index, relying on the meso-scale structure of porous material and the property of liquid, denotes the connectivity of pores in Representative Element Area (REA). If the conductivity of the porous material is anisotropic, the equivalent connectivity index is a second order tensor. Based on the basic theories of continuous mechanics and tensor analysis, relationship between area porosity and volumetric porosity of porous materials is deduced. Then a generalized expression, describing the relation between effective stress coefficient tensor and equivalent connectivity tensor of pores, is proposed, and the expression can be applied to isotropic media and also to anisotropic materials. Furthermore, evolution of porosity and equivalent connectivity index of the pore are studied in the strain space, and the method to determine the corresponding functions in expressions above is proposed using genetic algorithm and genetic programming. Two applications show that the results obtained by the method in this paper perfectly agree with the test data. This paper provides an important theoretical support to the coupled hydro-mechanical research.
文摘CNMC combines social responsibility with corporate vision as it expands in Africa TODAY non-ferrous metals(metals other than iron and alloys that do not contain an appreciable amount of iron) are an indispensable part of every aspect of our lives. From daily necessities like telephones and electric cookers,to sophisticated equipment like satellites and radar,non-ferrous
基金This study was supported in part by the National Natural Science Foundation of China(71973136 and 72061147002)the 2115 Talent Development Program of China Agricultural University.
文摘Over the past few decades,the Internet has rapidly diffused across China.The spread of the Internet has had a profound economic and social impact on Chinese rural areas.Existing research shows that Internet access significantly impacts agricultural production and improves smallholder farmers’income.Beyond these,the Internet can affect other dimensions of social welfare.However,research about the impact of Internet access on dietary quality in rural China remains scarce.This study utilizes multi-period panel data from Fixed Observation Point in rural China from 2009 to 2015 to estimate the impact of Internet access on dietary quality and food consumption of rural households and conducts a causal analysis.Regression models with time and household fixed effects allow robust estimation while reducing potential issues of unobserved heterogeneity.The estimates show that Internet access has significantly increased rural household dietary quality(measured by the Chinese Diet Balance Index).Further research finds that Internet access has increased the consumption of animal products,such as aquatic and dairy products.We also examine the underlying mechanisms.Internet access improves dietary quality and food consumption mainly through increasing household income and food expenditure.These results encourage the promotion of Internet access as a valuable tool for nutritional improvements,especially in rural areas.
基金supported by the Research Project of the Technical Inspection Center of Sinopec Shengli Oilfield Company.
文摘When a gas-liquid two-phase flow(GLTPF)enters a parallel separator through a T-junction,it generally splits unevenly.This phenomenon can seriously affect the operation efficiency and safety of the equipment located downstream.In order to investigate these aspects and,more specifically,the so-called bias phenomenon(all gas and liquid flowing to one pipe,while the other pipe is a liquid column that fluctuates up and down),laboratory experiments were carried out by using a T-junction connected to two parallel vertical pipes.Moreover,a GLTPF prediction model based on the principle of minimum potential energy was introduced.The research results indicate that this model can accurately predict the GLTPF state in parallel risers.The boundary of the slug flow and the churn flow in the opposite pipe can be predicted.Overall,according to the results,the pressure drop curves of the two-phase flow in the parallel risers are basically the same when there is no bias phenomenon,but the pressure drop in the parallel riser displays a large deviation when there is a slug flow-churn flow.Only when the parallel riser is in a state of asymmetric flow and one of the risers produces churn flow,the two-phase flow is prone to produce the bias phenomenon.
基金supported by the National Natural Science Foundation of China(Grant Nos.U1832120 and 11675265)S&T Program of Hebei(Grant No.236Z4601G)+4 种基金Scientific Research Foundation for the Introducing Returned Overseas Chinese Scholars of Hebei Province(Grant No.C20230360)Natural Science Foundation for Outstanding Young Scholars of Hebei Province(Grant No.A2020210012)Natural Science Foundation of Hebei Province(Grant No.A2021210010)Key Laboratory of High Precision Nuclear Spectroscopy,Institute of Modern Physics,Chinese Academy of Sciences(Grant No.IMPKFKT2021002)Key Project of Natural Science Foundation for Basic Discipline Research of Hebei Province(Grant No.A2023210064)。
文摘The effective liquid drop model(ELDM)is improved by introducing an accurate nuclear charge radius formula and an analytic expression for assaulting frequency.Within the improved effective liquid drop model(IMELDM),the experimental cluster radioactivity half-lives of the trans-lead region are calculated.It is shown that the accuracy of the IMELDM is improved compared with that of the ELDM.At last,the cluster radioactivity half-lives that are experimentally unavailable for the trans-lead nuclei are predicted by the IMELDM.These predictions may be useful for searching for new candidates for cluster radioactivity in future experiments.
基金supported by the Fund of Fujian Provincial Xi Jinping Thought on Socialism with Chinese Characteristics for a New Era(Grant No.FJ2023XZB057)Major Project Fund of Fujian Provincial Social Science Research Base(Grant No.FJ2023JDZ021).
文摘The digital economy,as a new emerging economic form,has become an important power for realizing Chinese-style modernization and promoting green development in China.This paper measures the digital economy and low-carbon transition index based on the data of 30 provinces in China from 2013 to 2020 and analyzes the mechanism and path of the digital economy affecting low-carbon transition using the fixed effect panel data model and the threshold effect model.It is found that,(1)The digital economy and low-carbon transition in China are various in different regions,with characteristics of being unbalanced and insufficient.(2)The digital economy significantly promotes low-carbon transition,with the greatest influence in the Central region,followed by the Eastern region and the Western region.Under different dimensions,the development of informatization and digital transactions promote low-carbon transition,but the development of the internet plays an inhibiting role.(3)The higher the degree of urbanization and environmental regulation,the greater the influence of the digital economy on low-carbon transition.
基金The project is partly supported by NSFC (19971085)the Doctoral Program Foundation of the Institute of High Education and the Special Foundation of Chinese Academy of Sciences.
文摘Bayes decision rule of variance components for one-way random effects model is derived and empirical Bayes (EB) decision rules are constructed by kernel estimation method. Under suitable conditions, it is shown that the proposed EB decision rules are asymptotically optimal with convergence rates near O(n-1/2). Finally, an example concerning the main result is given.
基金supported by National Natural Science Foundation of China (Nos.50836007, 10921062)
文摘A modelling study is performed to compare the plasma flow and heat transfer characteristics of low-power arc-heated thrusters (arcjets) for three different propellants: hydrogen, nitrogen and argon. The all-speed SIMPLE algorithm is employed to solve the governing equations, which take into account the effects of compressibility, Lorentz force and Joule heating, as well as the temperature- and pressure-dependence of the gas properties. The temperature, velocity and Mach number distributions calculated within the thruster nozzle obtained with different propellant gases are compared for the same thruster structure, dimensions, inlet-gas stagnant pressure and arc currents. The temperature distributions in the solid region of the anode-nozzle wall are also given. It is found that the flow and energy conversion processes in the thruster nozzle show many similar features for all three propellants. For example, the propellant is heated mainly in the near-cathode and constrictor region, with the highest plasma temperature appearing near the cathode tip; the flow transition from the subsonic to supersonic regime occurs within the constrictor region; the highest axial velocity appears inside the nozzle; and most of the input propellant flows towards the thruster exit through the cooler gas region near the anode-nozzle wall. However, since the properties of hydrogen, nitrogen and argon, especially their molecular weights, specific enthMpies and thermal conductivities, are different, there are appreciable differences in arcjet performance. For example, compared to the other two propellants, the hydrogen arcjet thruster shows a higher plasma temperature in the arc region, and higher axial velocity but lower temperature at the thruster exit. Correspondingly, the hydrogen arcjet thruster has the highest specific impulse and arc voltage for the same inlet stagnant pressure and arc current. The predictions of the modelling are compared favourably with available experimental results.
文摘In the present investigations, the antitumorigenic effect of black tea polyphenols (BTP) in twcrstage mouse skin model of carcinogenesis was studied. The animals were initiated with a single 'subcarcinogenic' topical dose (52 μg/200 μl acetone ) of 7, 12-dimethylbenzanthracene (DMBA). To evaluate the anti-tumour initiating activity, BTP was topically applied twice a week for three weeks prior to DMBA application, followed by topical treatment with 12-o-tetradecanoyl phorbol-13-acetate (TPA) (5 μg/200 μl acetone, 2x/wk. ) as promoter. For evaluation of antitumor promoting activity, BTP was applied prior to each treatment of TPA. BTP application showed marked inhibitory effect as antitumour initiator as well as antitumour promoter in mouse skin medel of two-stage carcinogenesis. Since initiation involves genetic pathway and tumour promotion involves epigenetic pathway, it seems that BTP exerts its antitumorigenic effect by altering both genetic and epigenetic pathways
文摘Fetr6 is an underground mine in which chromite is extracted using stope and pillar mining method. Despite of all improving works such as roof supporting and replacing of ore pillars with concrete pillars, pillar No. 19 failed and other pillars failed progressively as a domino effect and 4000 m2 of mine collapsed within a few minutes, consequently. For detail investigation, two 3-D numerical models were developed by 3Dec. The first, a base model, was used for estimation of stress on pillars just before failure and the other for investigation of rock burst in pillar No. 19. The results show that discontinuity parameters such as friction angle and shear stiffness is critical parameters in this pillar failure. In addition, it indicates that W/H ratio equal 0.3, the lack of ore extraction strategy and inadequate roof support are the major reasons for this failure. In this paper, the procedure of study was described.
基金supported by National Natural Science Foundation of China (11072179,11090334)Shanghai Leading Academic Discipline Project (B302)
文摘Due to the large quasi-piezoelectric d33 coefficient in the film thickness direction, cellular piezoelectret has emerged as a new kind of compliant electromechanical transducer materials. The macroscopic piezoelectric effect of cellular piezoelectret is closely related to the void microstructures as well as the material constants of host polymer. Complex void microstmctures are usually encountered in the optimum design of cellular piezoelectret polymer film with ad- vanced piezoelectric properties. Analysis of the effective electromechanical properties is generally needed. This article presents an overview of the recent progress on theoretical models and numerical simulation for the effective electromechanical properties of cellular piezoelectret. Emphasis is placed on our own works of cellular piezoelectret published in past several years.
基金Supported by the Fund of Science and Technology on Vacuum Technology and Physics Laboratory of Lanzhou Institute of Physics under Grant No YSC0715the National Natural Science Foundation of China under Grant No 62601210the Civil Aerospace Technology Research Project under Grant No D010509
文摘The effects of three different typical resistivity models(Spitzer, Z&L and M&G) on the performance of pulsed inductive acceleration plasma are studied. Numerical results show that their influences decrease with the increase of the plasma temperature. The significant discriminations among them appear at the plasma temperature lower than 2.5 eV, and the maximum gap of the pulsed inductive plasma accelerated efficiency is approximately 2.5%.Moreover, the pulsed inductive plasma accelerated efficiency is absolutely related to the dynamic impedance parameters, such as voltage, inductance, capacitance and flow rate. However, the distribution of the efficiency as a function of plasma temperature with three resistivity models has nothing to do with the dynamic impedance parameter.
基金The Specialized Research Fund for the Doctoral Program of Higher Education under contract No.20120041130002the National Key Project of Science and Technology under contract No.2011ZX 05056-001-02the Fundamental Research Funds for the Central Universities under contract No.DUT14ZD220
文摘Submarine landslides can cause severe damage to marine engineering structures. Their sliding velocity and runout distance are two major parameters for quantifying and analyzing the risk of submarine landslides.Currently, commercial calculation programs such as BING have limitations in simulating underwater soil movements. All of these processes can be consistently simulated through a smoothed particle hydrodynamics(SPH) depth integrated model. The basis of the model is a control equation that was developed to take into account the effects of soil consolidation and erosion. In this work, the frictional rheological mode has been used to perform a simulation study of submarine landslides. Time-history curves of the sliding body's velocity, height,and length under various conditions of water depth, slope gradient, contact friction coefficient, and erosion rate are compared; the maximum sliding distance and velocity are calculated; and patterns of variation are discussed.The findings of this study can provide a reference for disaster warnings and pipeline route selection.
基金supported by National Social Science Foundation of China(21BTJ068)。
文摘In this paper,we consider the statistical inference problems for the fixed effect and variance component functions in the two-way classification random effects model with skewnormal errors.Firstly,the exact test statistic for the fixed effect is constructed.Secondly,using the Bootstrap approach and generalized approach,the one-sided hypothesis testing and interval estimation problems for the single variance component,the sum and ratio of variance components are discussed respectively.Further,the Monte Carlo simulation results indicate that the exact test statistic performs well in the one-sided hypothesis testing problem for the fixed effect.And the Bootstrap approach is better than the generalized approach in the one-sided hypothesis testing problems for variance component functions in most cases.Finally,the above approaches are applied to the real data examples of the consumer price index and value-added index of three industries to verify their rationality and effectiveness.
基金supported by the Natural Science Foundation of China(11201345,11271136)
文摘It is well known that spline smoothing estimator relates to the Bayesian estimate under partially informative normal prior. In this paper, we derive the conditions for the pro- priety of the posterior in the nonparametric mixed effects model under this class of partially informative normal prior for fixed effect with inverse gamma priors on the variance compo- nents and hierarchical priors for covariance matrix of random effect, then we explore the Gibbs sampling procedure.
文摘We present a comprehensive numerical framework for the electrical and optical modeling and simulation of hybrid quantum dot light-emitting diodes(QD-LEDs).We propose a model known as hopping mobility to calculate the carrier mobility in the emissive organic layer doped with quantum dots(QDs).To evaluate the ability of this model to describe the electrical characteristics of QD-LEDs,the measured data of a fabricated QD-LED with different concentrations of QDs in the emissive layer were taken,and the corresponding calculations were performed based on the proposed model.The simulation results indicate that the hopping mobility model can describe the concentration dependence of the electrical behavior of the device.Then,based on the continuity equation for singlet and triplet excitons,the exciton density profiles of the devices with different QD concentrations were extracted.Subsequently,the corresponding luminance characteristics of the devices were calculated,where the results are in good agreement with the experimental data.
文摘By use of self-consistent field Xα scattered-wave (SCF-Xα-SW) method, the electronic structure was calculated for four models of Ti4Al14X (X=Al, Fe, Ni and Cu) clusters. The Ti4Al14X cluster was developed based on L12 Al3Ti-base intermetallic compound. The results are presented using the density of states (DOS) and one-electron properties, such as relative binding tendency between the atom and the model cluster, and hybrid bonding tendency between the alloying element and the host atoms. By comparing the four models of Ti4Al14X cluster, the effect of the Fe, Ni or Cu atom on the physical properties of Al3Ti-based L12 intermetallic compounds is analyzed. The results indicate that the addition of the Fe, Ni or Cu atom intensifies the relative binding tendency between Ti atom and Ti4Al14X cluster. It was found that the Fermi level (EF) lies in a maximum in the DOS for Ti4Al14Al cluster; on the contrary, the EF comes near a minimum tn the DOS for Ti4Al14X (X=Fe, Ni and Cu) cluster. Thus the L12 crystal structure for binary Al3Ti alloy is unstable, and the addition of the Fe, Ni or Cu atom to Al3Ti is benefical to stabilize L12 crystal structure. The calculation also shows that the Fe, Ni or Cu atom strengthens the hybrid bonding tendency between the central atom and the host atoms for Ti4Al14X cluster and thereby may lead to the constriction of the lattice of Al3Ti-base intermetallic compounds.
基金supported by National Natural Science Foundation of China (Nos.10875023,11175035)the Ph.D research program(No.200801411040 ) of Educational Ministry+1 种基金the Scientific and Technical Foundation of Liaoning Province (No.20082168)National Magnetic Confinement Fusion Science Program of China (Nos.2009GB106004,2008CB717801)
文摘The behavior of argon plasma driven by nanosecond pulsed plasma in a low-pressure plasma reactor is investigated using a global model, and the results are compared with the experimental measurements. The time evolution of plasma density and the electron energy probability function are calculated by solving the energy balance and Boltzmann equations. During and shortly after the discharge pulse, the electron energy probability function can be represented by a bi-Maxwellian distribution, indicating two energy groups of electrons. According to the effective electron temperature calculation, we find that there are more high-energy electrons that play an important role in the excitation and ionization processes than low-energy electrons. The effective electron temperature is also measured via optical emission spectroscopy to evaluate the simulation model. In the comparison, the simulation results are found to be in agreement with the measure- ments. Furthermore, variations of the effective electron temperature are presented versus other discharge parameters, such as pulse width time, pulse rise time and gas pressure.
文摘The prophylactic effects of Chinese propolis against cypermethrin toxicity were evaluated by performing ovary and uterus histopathology, as well as by characterizing ovarian function, embryos, and litters. Cypermethrin induced atypia in the ovary and uterus, and decreased the ovulation sites and the number of embryos. Cypermethrin-induced oxidative stress during pregnancy, decreased the parturition rate as well as the number and weight of offspring and increased the incidence of morphological malformations in the offspring. Administration of propolis to cypermethrin-treated animals mitigated cypermethrin-induced reproductive toxicity.