Owing to intensified globalization and informatization,the structures of the urban scale hierarchy and urban networks between cities have become increasingly intertwined,resulting in different spatial effects.Therefor...Owing to intensified globalization and informatization,the structures of the urban scale hierarchy and urban networks between cities have become increasingly intertwined,resulting in different spatial effects.Therefore,this paper analyzes the spatial interaction between urban scale hierarchy and urban networks in China from 2019 to 2023,drawing on Baidu migration data and employing a spatial simultaneous equation model.The results reveal a significant positive spatial correlation between cities with higher hierarchy and those with greater network centrality.Within a static framework,we identify a positive interaction between urban scale hierarchy and urban network centrality,while their spatial cross-effects manifest as negative neighborhood interactions based on geographical distance and positive cross-scale interactions shaped by network connections.Within a dynamic framework,changes in urban scale hierarchy and urban networks are mutually reinforcing,thereby widening disparities within the urban hierarchy.Furthermore,an increase in a city’s network centrality had a dampening effect on the population growth of neighboring cities and network-connected cities.This study enhances understanding of the spatial organisation of urban systems and offers insights for coordinated regional development.展开更多
It is now common practice to perform simultaneous traveltime inversion for the velocity field and the reflector geometry in reflection/refraction tomography, or the velocity field and the hypocenter locations in regio...It is now common practice to perform simultaneous traveltime inversion for the velocity field and the reflector geometry in reflection/refraction tomography, or the velocity field and the hypocenter locations in regional earthquake tomography, but seldom are all three classes of model parameters updated simultaneously. This is mainly due to the trade-off between the different types of model parameters and the lack of different seismic phases to constrain the model parameters. Using a spherical-coordinate ray tracing algorithm for first and later（primary reflected） arrival tracing algorithm in combination with a popular linearized inversion solver, it is possible to simultaneously recover the three classes of model parameters in regional or global tomographic studies. In this paper we incorporate the multistage irregular shortest-path ray tracing algorithm（in a spherical coordinate system） with a subspace inversion solver to formulate a simultaneous inversion algorithm for triple model parameters updating using direct and later arrival time information.Comparison tests for two sets of data（noise free and added noise） indicate that the new triple-class parameter inversion algorithm is capable of obtaining nearly the same results as the double-class parameter inversion scheme. Furthermore,the proposed multi-parameter type inversion method is not sensitive to a modest level of picking error in the traveltime data, and also performs well with a relatively large uncertainty in earthquake hypocentral locations. This shows it to be a feasible and promising approach in regional or global tomographic applications.展开更多
In this paper, the authors study the effectiveness of the Japanese monetary policy set by the Bank of Japan (BOJ) to contrast the three major crises that the country has experienced since the second half of the 90s: t...In this paper, the authors study the effectiveness of the Japanese monetary policy set by the Bank of Japan (BOJ) to contrast the three major crises that the country has experienced since the second half of the 90s: that of the lost decade, that of 2008 and that of the Covid-19 pandemic. To this end, they use a particular type of mathematical-statistical model that is widely applied today in the economic field, namely a simultaneous equation model (SEM). This simultaneous equation model is estimated through an Iteratively reweighted least squares (IRLS) using quarterly historical series in the sample period Q1 1994 - Q2 2020. All data are in real terms. The results, appropriately compared with those of other authors, suggest that the monetary policy has a (limited) impact only on the interbank market. The fiscal policy, instead, has a greater ability to influence the money supply, the private consumption and the inflation expectations.展开更多
This study develops crash rate prediction models based on the premise that crash frequencies observed from adjacent paired non-weaving and weaving freeway segments are spatially correlated and therefore requires a sim...This study develops crash rate prediction models based on the premise that crash frequencies observed from adjacent paired non-weaving and weaving freeway segments are spatially correlated and therefore requires a simultaneous equation modeling approach. Simultaneous equation models for paired freeway non-weaving segments and weaving segments along with combined three freeway segments upstream and downstream were developed to investigate the relationship of crash rate with freeway characteristics. The endogenous variables have significant coefficients which indicate that unobserved variables exist on these contiguous segments, resulting in different crash rates. AADT is a variable that can show the interaction between the traffic and crashes on these contiguous segments. The results corroborate such an interaction. By comparing the simultaneous equation model and the multiple linear regression model, it is shown that more model parameters in the simultaneous models are significant than those from linear regression model. This demonstrates the existence of the correlation between the interchange and between-interchange segments. It is crucial that some variables like segment length can be identified significant in the simultaneous model, which provides a way to quantify the safety impact of freeway development.展开更多
On the basis of using entropy weight method to measure China’s education poverty alleviation and rural revitalization evaluation indicators, using the panel data of 30 provinces in China (excluding Xizang, Hong Kong,...On the basis of using entropy weight method to measure China’s education poverty alleviation and rural revitalization evaluation indicators, using the panel data of 30 provinces in China (excluding Xizang, Hong Kong, Macao and Taiwan) from 2012 to 2021, a spatial panel simultaneous equation model is constructed based on adjacency matrix, geographical distance matrix and economic geographical distance matrix deeply study the interaction mechanism and spatial spillover effects between education poverty alleviation and rural revitalization through the generalized spatial three-stage least squares method (GS3SLS). The results indicate that there is a significant spatial spillover effect and a positive spatial correlation between education poverty alleviation and rural revitalization, and there is a significant interactive effect between the two variables, while promoting each other positively. Therefore, the government should clarify the deep relationship between education poverty alleviation and rural revitalization based on the current background, and better consolidate and expand the effective connection between the achievements of education poverty alleviation and rural revitalization.展开更多
This article explores the factors and mechanism driving the land-use conversion at regional level by developing and using an econometric approach which is called the simultaneous equations model （SEM）. A case study ...This article explores the factors and mechanism driving the land-use conversion at regional level by developing and using an econometric approach which is called the simultaneous equations model （SEM）. A case study in Jiangxi Province of China is conducted by establishing the SEM, which consists of three equations including agricultural production, land conversion of cultivated land to built-up area and land conversion of cultivated land to forest cover/grassland from 1988 to 2005. And then this paper employs the method of piecewise estimation to represent the influences of the factors such as population, society, economy, location and geophysical conditions on the process of land-use conversion in Jiangxi Province. Estimation results show that population is a predominant factor driving the land-use conversion at counties, while social and economic factors are determinant factors in the short term for the entire Jiangxi Province. Specifically, the size of agricultural population and the magnitude of agricultural input determine the agricultural production to a large extent; population size, plain area proportion at counties and land management policies together affect the direction and magnitude of conversion between cultivated land and built-up area; agricultural population proportion, terrain slope, grain production and non-agricultural industry promote the conversion of cultivated land to forest cover/grassland. Furthermore, the explored mechanism also reveals the underlying causes of the land use changes driven by a series of factors in Jiangxi Province. Finally, this paper concludes that factors proven to play an important role in driving the land-use conversion need to be considered when the land management agencies make out the land use planning to optimize the land use, expand the agricultural production, and conserve the cultivated land.展开更多
The effect of vegetation on the water-heat exchange in the freezing-thawing processes of active layer is one of the key issues in the study of land surface processes and in predicting the response of alpine ecosystems...The effect of vegetation on the water-heat exchange in the freezing-thawing processes of active layer is one of the key issues in the study of land surface processes and in predicting the response of alpine ecosystems to climate change in permafrost regions.In this study,we used the simultaneous heat and water model to investigate the effects of plant canopy on surface and subsurface hydrothermal dynamics in the Fenghuoshan area of the QinghaiTibet Plateau by changing the leaf area index(LAI)and keeping other variables constant.Results showed that the sensible heat,latent heat and net radiation are increased with an increase in the LAI.However,the ground heat flux decreased with an increasing LAI.The annual total evapotranspiration and vegetation transpiration ranged from-16%to 9%and-100%to 15%,respectively,in response to extremes of doubled and zero LAI,respectively.There was a negative feedback between vegetation and the volumetric unfrozen water content at 0.2 m through changing evapotranspiration.The simulation results of soil temperature and moisture suggest that better vegetation conditions are conducive to maintaining the thermal stability of the underlying permafrost,and the advanced initial thawing time and increasing thawing rate of soil ice with the increase in the LAI may have a great influence on the timing and magnitude of supra-permafrost groundwater.This study quantifies the impact of vegetation change on surface and subsurface hydrothermal processes and provides a basic understanding for evaluating the impact of vegetation degradation on the water-heat exchange in permafrost regions under climate change.展开更多
This paper studies the endogeneity of WTO dummy variable in the gravity model about the trade in the region of China and ASEAN. We first present a two-stage test approach for the endogeneity of WTO dummy, then transfo...This paper studies the endogeneity of WTO dummy variable in the gravity model about the trade in the region of China and ASEAN. We first present a two-stage test approach for the endogeneity of WTO dummy, then transform the endogeneity problem to a simultaneous system about WTO and trade, and construct an MLE estimation approach to the simultaneous model. The estimate of the coefficient of WTO dummy is positive, as opposed to the negative sign in the exogeneity case. From the estimation of the endogenous model, WTO has creation fold effect and strong trade diversion effect on export model in the region.展开更多
Interaction of environmental pollution between peripheral areas has become a central topic in the field of resources and environment but little is known about the actual impact on peripheral areas in the current liter...Interaction of environmental pollution between peripheral areas has become a central topic in the field of resources and environment but little is known about the actual impact on peripheral areas in the current literature.This paper sets out a simultaneous equation model to investigate the spillover effect of environmental pollution between China's peripheral areas utilizing the panel data of 218 cities in China.Making use of indicators for measuring the impact on environmental pollution,it identifies that environmental pollution between cities of China has a significant two-way spillover effect.After standardization of variables,it is found that the spillover effect of peripheral areas on urban environmental pollution cannot be neglected.Nearly,a third of the environmental pollution level in a city is induced by the environmental pollution in peripheral areas.If the indicator of environmental pollution in peripheral areas is missing,wrong conclusions will be drawn.Therefore,government should shift the emphasis of environmental regulation from local to global,and improve the overall environmental quality through coordinated management of regional environment.展开更多
Econometric simultaneous equation models play an important role in making economic policies, analyzing economic structure and economic forecasting. This paper presents local linear estimators by TSLS with variable ban...Econometric simultaneous equation models play an important role in making economic policies, analyzing economic structure and economic forecasting. This paper presents local linear estimators by TSLS with variable bandwidth for every structural equation in semi-parametric simultaneous equation models in econometrics. The properties under large sample size were studied by using the asymptotic theory when all variables were random. The results show that the estimators of the parameters have consistency and asymptotic normality, and their convergence rates are equal to n^-1/2. And the estimator of the nonparametric function has the consistency and asymptotic normality in interior points and its rate of convergence is equal to the optimal convergence rate of the nonparametric function estimation.展开更多
The common models used for grey system predictions include the GM(1, 1), the GM(1, N),the GM(N, 1), and so on, but their whitening equations are all single ordinary differential equations.However, objects and factors ...The common models used for grey system predictions include the GM(1, 1), the GM(1, N),the GM(N, 1), and so on, but their whitening equations are all single ordinary differential equations.However, objects and factors generally form a whole through mutual restrictions and connections when the objective world is developing and changing continuously. In other words, variables affect each other. The relationship can’t be properly reflected by the single differential equation. Therefore, the paper proposes a novel simultaneous grey model. The paper gives a modeling method of simultaneous grey model SGM(1, 2) with 2 interactive variables. The example proves that the simultaneous grey model has high precision and improves the precision significantly compared with the conventional single grey model. The new method proposed enriches the grey modeling method system and has important significance for the in-depth study, popularization and application of grey models.展开更多
Following the Paris Agreement,economic development demands energy services while reducing emissions.This study focuses on non-residential natural gas consumption,which plays a crucial role in the energy transition;how...Following the Paris Agreement,economic development demands energy services while reducing emissions.This study focuses on non-residential natural gas consumption,which plays a crucial role in the energy transition;however,market-based mechanisms are still in the early stages and have not yet been explored.Based on the analysis of data collected from 2000 to 2020 in China,this study constructs a simultaneous equation model to analyze the rebound and induced effects of non-residential natural gas consumption.This paper finds that industrial economic growth has a significant promoting effect on nonresidential gas consumption.In addition,implementing and promoting natural gas utilization policies and increases in natural gas price can significantly reduce gas consumption intensity.This article innovatively calculates the rebound and induced effects of nonresidential gas consumption,providing a decision-making reference for accelerating the realization of the dual-carbon goal.展开更多
A review of ten-year's practice in developing the improved simultaneous physical retrieval method(ISPRM)is given in the hope that some creative ideas can be drawn from it.The improvement upon the SPRM is associate...A review of ten-year's practice in developing the improved simultaneous physical retrieval method(ISPRM)is given in the hope that some creative ideas can be drawn from it.The improvement upon the SPRM is associated with the under-determinedness of this ill-posed inverse problem.In our experiment,the precondition is observed that prior information must be independent of the satellite measurements.The well-posed retrieval theory has told us that the forward process is fundamental for the retrieval,and it is the bridge between the input of satellite radiance and the output of retrievals.In order to obtain a better result from the forward process. the full advantage of every prior information available must be taken.It is necessary to turn the ill- posed inverse problem into the well-posed one.Then by using the Ridge regression or Bayes algorithm to find the optimal combination among the first guess,the theoretical analogue information and the satellite observations,the impact of the under-determinedness of this inverse problem on the numerical solution is minimized.展开更多
Scientific and technological(S&T)innovation and industrial structure upgrading have become two strategies to achieve high-quality economic development under the new pattern of development in China.Exploring the me...Scientific and technological(S&T)innovation and industrial structure upgrading have become two strategies to achieve high-quality economic development under the new pattern of development in China.Exploring the mechanism through which the former two affect the latter is of great significance to realize high-quality economic development and socialist modernization.Based on panel data of 30 provinces(municipalities,autonomous regions)from 2008 to 2017,this paper adopts the simultaneous equation model to empirically investigate the effect of S&T innovation and industrial structure upgrading on high-quality economic development.The study reveals that S&T innovation can significantly promote industrial structure upgrading and high-quality economic development,while industrial structure upgrading imposes a significantly negative effect on high-quality economic development.However,S&T innovation can offset such a negative effect and promote high-quality development indirectly.S&T innovation influences high-quality development in a dual path.To be specific,the former produces both a direct influence on the latter,but also an indirect influence through industrial structure upgrading.展开更多
In this Letter, we discuss Raman–Nath acousto-optic diffraction, and a new model of Raman–Nath acousto-optic diffraction is presented. The model is based on the individual and simultaneous occurrences of phase-grati...In this Letter, we discuss Raman–Nath acousto-optic diffraction, and a new model of Raman–Nath acousto-optic diffraction is presented. The model is based on the individual and simultaneous occurrences of phase-grating diffraction and the Doppler effect and optical phase modulation and photon–phonon scattering. We find that the optical phase modulation can cause temporal and spatial fluctuations of the diffracted light power escaping from the acoustic field.展开更多
Introduction:The effects of temperature have largely been under-examined in climate change studies.This study examines both direct and indirect effects of temperature on environmental degradation using the sample of 1...Introduction:The effects of temperature have largely been under-examined in climate change studies.This study examines both direct and indirect effects of temperature on environmental degradation using the sample of 103 middle-income countries from 1985 to 2019.Unlike previous studies in which a single equation approach is utilized,our study considers the simultaneous equations modelling to examine the energy-growth-environment nexus incorporating temperature and corruption.The difference and system generalized method of moments estimations for panel data are used.Outcomes:Empirical results from this paper confirm both the direct and indirect effects(via energy consumption)of temperature on environmental degradation.We find corruption harms economic growth in middle-income countries.The continued use of fossil fuel energy in energy consumption deteriorates environmental quality.Our findings confirm the critical role of the services sector in supporting economic growth and reducing emerging consumption,leading to increased environmental quality.Conclusion:Findings from our study reconfirm the vital role of renewable energy and its extended use in achieving dual objectives of supporting economic growth and improving the environmental quality in middle-income countries.展开更多
Based on the practice of improved simultaneous physical retrieval model(ISPRM),in the light of the functional analysis approach,the variational simultaneous physical retrieval model (VSPRM)has been developed.Its appro...Based on the practice of improved simultaneous physical retrieval model(ISPRM),in the light of the functional analysis approach,the variational simultaneous physical retrieval model (VSPRM)has been developed.Its approximation of 1st degree is VSPRM1,which is identical with the ISPRM.Its approximation of 2nd degree is VSPRM2,more advanced than the VSPRM1. This paper has analyzed the function of VSPRM2,pointing out the potentiality of synergy retrieval of this model.Also,it has dealt with the problem of parameterization of water vapor's kernel functions and retrieval of water vapor remote sensing. Because of the characteristics of this strong ill posed inverse problem,prior information must be used wisely in order to get the accurate calculation of radiance R.In the previous paper,we discussed how to build the best first guess field,the way to determine the P_s and to correct the calculation of radiance.In this paper,we continue discussing in depth about the calculation of transmittance,the determination of surface parameters and the selection for an optimum combination of channels for the low-level sounding. The long-term experiment and comparison work under operational environment have shown that the ISPRM is useful for retrieval of temperature and water vapor parameters over China including the Tibetan Plateau,and it further proves the scientific nature of well-posed inverse theory.展开更多
基金Under the auspices of the National Natural Science Foundation of China(No.42371222,41971167)Fundamental Scientific Research Funds of Central China Normal University(No.CCNU24ZZ120)。
文摘Owing to intensified globalization and informatization,the structures of the urban scale hierarchy and urban networks between cities have become increasingly intertwined,resulting in different spatial effects.Therefore,this paper analyzes the spatial interaction between urban scale hierarchy and urban networks in China from 2019 to 2023,drawing on Baidu migration data and employing a spatial simultaneous equation model.The results reveal a significant positive spatial correlation between cities with higher hierarchy and those with greater network centrality.Within a static framework,we identify a positive interaction between urban scale hierarchy and urban network centrality,while their spatial cross-effects manifest as negative neighborhood interactions based on geographical distance and positive cross-scale interactions shaped by network connections.Within a dynamic framework,changes in urban scale hierarchy and urban networks are mutually reinforcing,thereby widening disparities within the urban hierarchy.Furthermore,an increase in a city’s network centrality had a dampening effect on the population growth of neighboring cities and network-connected cities.This study enhances understanding of the spatial organisation of urban systems and offers insights for coordinated regional development.
基金partially supported by the Doctoral Programming Research Fund of Higher Education, Chinese Ministry of Education (No. 20110205110010)
文摘It is now common practice to perform simultaneous traveltime inversion for the velocity field and the reflector geometry in reflection/refraction tomography, or the velocity field and the hypocenter locations in regional earthquake tomography, but seldom are all three classes of model parameters updated simultaneously. This is mainly due to the trade-off between the different types of model parameters and the lack of different seismic phases to constrain the model parameters. Using a spherical-coordinate ray tracing algorithm for first and later（primary reflected） arrival tracing algorithm in combination with a popular linearized inversion solver, it is possible to simultaneously recover the three classes of model parameters in regional or global tomographic studies. In this paper we incorporate the multistage irregular shortest-path ray tracing algorithm（in a spherical coordinate system） with a subspace inversion solver to formulate a simultaneous inversion algorithm for triple model parameters updating using direct and later arrival time information.Comparison tests for two sets of data（noise free and added noise） indicate that the new triple-class parameter inversion algorithm is capable of obtaining nearly the same results as the double-class parameter inversion scheme. Furthermore,the proposed multi-parameter type inversion method is not sensitive to a modest level of picking error in the traveltime data, and also performs well with a relatively large uncertainty in earthquake hypocentral locations. This shows it to be a feasible and promising approach in regional or global tomographic applications.
文摘In this paper, the authors study the effectiveness of the Japanese monetary policy set by the Bank of Japan (BOJ) to contrast the three major crises that the country has experienced since the second half of the 90s: that of the lost decade, that of 2008 and that of the Covid-19 pandemic. To this end, they use a particular type of mathematical-statistical model that is widely applied today in the economic field, namely a simultaneous equation model (SEM). This simultaneous equation model is estimated through an Iteratively reweighted least squares (IRLS) using quarterly historical series in the sample period Q1 1994 - Q2 2020. All data are in real terms. The results, appropriately compared with those of other authors, suggest that the monetary policy has a (limited) impact only on the interbank market. The fiscal policy, instead, has a greater ability to influence the money supply, the private consumption and the inflation expectations.
文摘This study develops crash rate prediction models based on the premise that crash frequencies observed from adjacent paired non-weaving and weaving freeway segments are spatially correlated and therefore requires a simultaneous equation modeling approach. Simultaneous equation models for paired freeway non-weaving segments and weaving segments along with combined three freeway segments upstream and downstream were developed to investigate the relationship of crash rate with freeway characteristics. The endogenous variables have significant coefficients which indicate that unobserved variables exist on these contiguous segments, resulting in different crash rates. AADT is a variable that can show the interaction between the traffic and crashes on these contiguous segments. The results corroborate such an interaction. By comparing the simultaneous equation model and the multiple linear regression model, it is shown that more model parameters in the simultaneous models are significant than those from linear regression model. This demonstrates the existence of the correlation between the interchange and between-interchange segments. It is crucial that some variables like segment length can be identified significant in the simultaneous model, which provides a way to quantify the safety impact of freeway development.
文摘On the basis of using entropy weight method to measure China’s education poverty alleviation and rural revitalization evaluation indicators, using the panel data of 30 provinces in China (excluding Xizang, Hong Kong, Macao and Taiwan) from 2012 to 2021, a spatial panel simultaneous equation model is constructed based on adjacency matrix, geographical distance matrix and economic geographical distance matrix deeply study the interaction mechanism and spatial spillover effects between education poverty alleviation and rural revitalization through the generalized spatial three-stage least squares method (GS3SLS). The results indicate that there is a significant spatial spillover effect and a positive spatial correlation between education poverty alleviation and rural revitalization, and there is a significant interactive effect between the two variables, while promoting each other positively. Therefore, the government should clarify the deep relationship between education poverty alleviation and rural revitalization based on the current background, and better consolidate and expand the effective connection between the achievements of education poverty alleviation and rural revitalization.
基金National Natural Science Foundation of China, No.40801231Knowledge Innovation Program of the CAS, No.KZCX2-YW-326-1+3 种基金 No.KZCX2-YW-305-2 No.KSCX1-YW-09-04National Key Technology R&D Program of China, No.2006BAC08B03 No.2006BAC08B06
文摘This article explores the factors and mechanism driving the land-use conversion at regional level by developing and using an econometric approach which is called the simultaneous equations model （SEM）. A case study in Jiangxi Province of China is conducted by establishing the SEM, which consists of three equations including agricultural production, land conversion of cultivated land to built-up area and land conversion of cultivated land to forest cover/grassland from 1988 to 2005. And then this paper employs the method of piecewise estimation to represent the influences of the factors such as population, society, economy, location and geophysical conditions on the process of land-use conversion in Jiangxi Province. Estimation results show that population is a predominant factor driving the land-use conversion at counties, while social and economic factors are determinant factors in the short term for the entire Jiangxi Province. Specifically, the size of agricultural population and the magnitude of agricultural input determine the agricultural production to a large extent; population size, plain area proportion at counties and land management policies together affect the direction and magnitude of conversion between cultivated land and built-up area; agricultural population proportion, terrain slope, grain production and non-agricultural industry promote the conversion of cultivated land to forest cover/grassland. Furthermore, the explored mechanism also reveals the underlying causes of the land use changes driven by a series of factors in Jiangxi Province. Finally, this paper concludes that factors proven to play an important role in driving the land-use conversion need to be considered when the land management agencies make out the land use planning to optimize the land use, expand the agricultural production, and conserve the cultivated land.
基金This study was supported by the National Nature Science Foundation of China(No.41671015,No.42071027,No.41890821)。
文摘The effect of vegetation on the water-heat exchange in the freezing-thawing processes of active layer is one of the key issues in the study of land surface processes and in predicting the response of alpine ecosystems to climate change in permafrost regions.In this study,we used the simultaneous heat and water model to investigate the effects of plant canopy on surface and subsurface hydrothermal dynamics in the Fenghuoshan area of the QinghaiTibet Plateau by changing the leaf area index(LAI)and keeping other variables constant.Results showed that the sensible heat,latent heat and net radiation are increased with an increase in the LAI.However,the ground heat flux decreased with an increasing LAI.The annual total evapotranspiration and vegetation transpiration ranged from-16%to 9%and-100%to 15%,respectively,in response to extremes of doubled and zero LAI,respectively.There was a negative feedback between vegetation and the volumetric unfrozen water content at 0.2 m through changing evapotranspiration.The simulation results of soil temperature and moisture suggest that better vegetation conditions are conducive to maintaining the thermal stability of the underlying permafrost,and the advanced initial thawing time and increasing thawing rate of soil ice with the increase in the LAI may have a great influence on the timing and magnitude of supra-permafrost groundwater.This study quantifies the impact of vegetation change on surface and subsurface hydrothermal processes and provides a basic understanding for evaluating the impact of vegetation degradation on the water-heat exchange in permafrost regions under climate change.
文摘This paper studies the endogeneity of WTO dummy variable in the gravity model about the trade in the region of China and ASEAN. We first present a two-stage test approach for the endogeneity of WTO dummy, then transform the endogeneity problem to a simultaneous system about WTO and trade, and construct an MLE estimation approach to the simultaneous model. The estimate of the coefficient of WTO dummy is positive, as opposed to the negative sign in the exogeneity case. From the estimation of the endogenous model, WTO has creation fold effect and strong trade diversion effect on export model in the region.
基金This paper is funded by the Innovative Talents Support Program of Liaoning Province in China[Grant number.WR2016014].
文摘Interaction of environmental pollution between peripheral areas has become a central topic in the field of resources and environment but little is known about the actual impact on peripheral areas in the current literature.This paper sets out a simultaneous equation model to investigate the spillover effect of environmental pollution between China's peripheral areas utilizing the panel data of 218 cities in China.Making use of indicators for measuring the impact on environmental pollution,it identifies that environmental pollution between cities of China has a significant two-way spillover effect.After standardization of variables,it is found that the spillover effect of peripheral areas on urban environmental pollution cannot be neglected.Nearly,a third of the environmental pollution level in a city is induced by the environmental pollution in peripheral areas.If the indicator of environmental pollution in peripheral areas is missing,wrong conclusions will be drawn.Therefore,government should shift the emphasis of environmental regulation from local to global,and improve the overall environmental quality through coordinated management of regional environment.
基金This project is supported by National Natural Science Foundation of China （70371025）
文摘Econometric simultaneous equation models play an important role in making economic policies, analyzing economic structure and economic forecasting. This paper presents local linear estimators by TSLS with variable bandwidth for every structural equation in semi-parametric simultaneous equation models in econometrics. The properties under large sample size were studied by using the asymptotic theory when all variables were random. The results show that the estimators of the parameters have consistency and asymptotic normality, and their convergence rates are equal to n^-1/2. And the estimator of the nonparametric function has the consistency and asymptotic normality in interior points and its rate of convergence is equal to the optimal convergence rate of the nonparametric function estimation.
基金Supported by the National Natural Science Foundation of China (11401418)。
文摘The common models used for grey system predictions include the GM(1, 1), the GM(1, N),the GM(N, 1), and so on, but their whitening equations are all single ordinary differential equations.However, objects and factors generally form a whole through mutual restrictions and connections when the objective world is developing and changing continuously. In other words, variables affect each other. The relationship can’t be properly reflected by the single differential equation. Therefore, the paper proposes a novel simultaneous grey model. The paper gives a modeling method of simultaneous grey model SGM(1, 2) with 2 interactive variables. The example proves that the simultaneous grey model has high precision and improves the precision significantly compared with the conventional single grey model. The new method proposed enriches the grey modeling method system and has important significance for the in-depth study, popularization and application of grey models.
基金the National Natural Science Foundation of China[72373116]the National Natural Science Foundation of China[71874133]+3 种基金the Youth Innovation Team of Shaanxi Universities[2020e68]the Shaanxi Province Qin Chuangyuan“scientistþengineer”team building project[2022KXJ-007]the Shaanxi Province“High-level Talents Special Support Program”Youth Top-notch Talents Project[TZ0153]the National Natural Science Foundation of China(Youth Program,72203164).
文摘Following the Paris Agreement,economic development demands energy services while reducing emissions.This study focuses on non-residential natural gas consumption,which plays a crucial role in the energy transition;however,market-based mechanisms are still in the early stages and have not yet been explored.Based on the analysis of data collected from 2000 to 2020 in China,this study constructs a simultaneous equation model to analyze the rebound and induced effects of non-residential natural gas consumption.This paper finds that industrial economic growth has a significant promoting effect on nonresidential gas consumption.In addition,implementing and promoting natural gas utilization policies and increases in natural gas price can significantly reduce gas consumption intensity.This article innovatively calculates the rebound and induced effects of nonresidential gas consumption,providing a decision-making reference for accelerating the realization of the dual-carbon goal.
基金Supported by NNSF of China under Grant(49794030#)National"973"Program No.4 (G1998040909#).
文摘A review of ten-year's practice in developing the improved simultaneous physical retrieval method(ISPRM)is given in the hope that some creative ideas can be drawn from it.The improvement upon the SPRM is associated with the under-determinedness of this ill-posed inverse problem.In our experiment,the precondition is observed that prior information must be independent of the satellite measurements.The well-posed retrieval theory has told us that the forward process is fundamental for the retrieval,and it is the bridge between the input of satellite radiance and the output of retrievals.In order to obtain a better result from the forward process. the full advantage of every prior information available must be taken.It is necessary to turn the ill- posed inverse problem into the well-posed one.Then by using the Ridge regression or Bayes algorithm to find the optimal combination among the first guess,the theoretical analogue information and the satellite observations,the impact of the under-determinedness of this inverse problem on the numerical solution is minimized.
基金This paper is the phased achievement of Gansu Philosophy and Social Science Planning Projet"Research on Policy Support for the Development of Private Economy in Gansu Province from the Perspective of New Political and Business Relations"(No.19YB046).
文摘Scientific and technological(S&T)innovation and industrial structure upgrading have become two strategies to achieve high-quality economic development under the new pattern of development in China.Exploring the mechanism through which the former two affect the latter is of great significance to realize high-quality economic development and socialist modernization.Based on panel data of 30 provinces(municipalities,autonomous regions)from 2008 to 2017,this paper adopts the simultaneous equation model to empirically investigate the effect of S&T innovation and industrial structure upgrading on high-quality economic development.The study reveals that S&T innovation can significantly promote industrial structure upgrading and high-quality economic development,while industrial structure upgrading imposes a significantly negative effect on high-quality economic development.However,S&T innovation can offset such a negative effect and promote high-quality development indirectly.S&T innovation influences high-quality development in a dual path.To be specific,the former produces both a direct influence on the latter,but also an indirect influence through industrial structure upgrading.
基金supported by the Science and Technology Program of Fujian Province of China (No. 2015J01301)the National Natural Science Foundation of China (No. 61575043)
文摘In this Letter, we discuss Raman–Nath acousto-optic diffraction, and a new model of Raman–Nath acousto-optic diffraction is presented. The model is based on the individual and simultaneous occurrences of phase-grating diffraction and the Doppler effect and optical phase modulation and photon–phonon scattering. We find that the optical phase modulation can cause temporal and spatial fluctuations of the diffracted light power escaping from the acoustic field.
基金This study is funded by Ho Chi Minh City Open University(E2022.1.01)。
文摘Introduction:The effects of temperature have largely been under-examined in climate change studies.This study examines both direct and indirect effects of temperature on environmental degradation using the sample of 103 middle-income countries from 1985 to 2019.Unlike previous studies in which a single equation approach is utilized,our study considers the simultaneous equations modelling to examine the energy-growth-environment nexus incorporating temperature and corruption.The difference and system generalized method of moments estimations for panel data are used.Outcomes:Empirical results from this paper confirm both the direct and indirect effects(via energy consumption)of temperature on environmental degradation.We find corruption harms economic growth in middle-income countries.The continued use of fossil fuel energy in energy consumption deteriorates environmental quality.Our findings confirm the critical role of the services sector in supporting economic growth and reducing emerging consumption,leading to increased environmental quality.Conclusion:Findings from our study reconfirm the vital role of renewable energy and its extended use in achieving dual objectives of supporting economic growth and improving the environmental quality in middle-income countries.
基金NNSF of China(49794030#).National"973"No.4(G1998040909#)and 863-308(863-2-7-4-12#).
文摘Based on the practice of improved simultaneous physical retrieval model(ISPRM),in the light of the functional analysis approach,the variational simultaneous physical retrieval model (VSPRM)has been developed.Its approximation of 1st degree is VSPRM1,which is identical with the ISPRM.Its approximation of 2nd degree is VSPRM2,more advanced than the VSPRM1. This paper has analyzed the function of VSPRM2,pointing out the potentiality of synergy retrieval of this model.Also,it has dealt with the problem of parameterization of water vapor's kernel functions and retrieval of water vapor remote sensing. Because of the characteristics of this strong ill posed inverse problem,prior information must be used wisely in order to get the accurate calculation of radiance R.In the previous paper,we discussed how to build the best first guess field,the way to determine the P_s and to correct the calculation of radiance.In this paper,we continue discussing in depth about the calculation of transmittance,the determination of surface parameters and the selection for an optimum combination of channels for the low-level sounding. The long-term experiment and comparison work under operational environment have shown that the ISPRM is useful for retrieval of temperature and water vapor parameters over China including the Tibetan Plateau,and it further proves the scientific nature of well-posed inverse theory.
