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Computer Methodologies for the Comparison of Some Efficient Derivative FreeSimultaneous Iterative Methods for Finding Roots of Non-Linear Equations 被引量:1
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作者 Yuming Chu Naila Rafiq +3 位作者 Mudassir Shams Saima Akram Nazir Ahmad Mir Humaira Kalsoom 《Computers, Materials & Continua》 SCIE EI 2021年第1期275-290,共16页
In this article,we construct the most powerful family of simultaneous iterative method with global convergence behavior among all the existing methods in literature for finding all roots of non-linear equations.Conver... In this article,we construct the most powerful family of simultaneous iterative method with global convergence behavior among all the existing methods in literature for finding all roots of non-linear equations.Convergence analysis proved that the order of convergence of the family of derivative free simultaneous iterative method is nine.Our main aim is to check out the most regularly used simultaneous iterative methods for finding all roots of non-linear equations by studying their dynamical planes,numerical experiments and CPU time-methodology.Dynamical planes of iterative methods are drawn by using MATLAB for the comparison of global convergence properties of simultaneous iterative methods.Convergence behavior of the higher order simultaneous iterative methods are also illustrated by residual graph obtained from some numerical test examples.Numerical test examples,dynamical behavior and computational efficiency are provided to present the performance and dominant efficiency of the newly constructed derivative free family of simultaneous iterative method over existing higher order simultaneous methods in literature. 展开更多
关键词 Non-linear equation iterative method simultaneous method basins of attractions computational efficiency
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A System of Simultaneous Equations (SEM) for the Study of the Effectiveness of the Japanese Monetary Policy
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作者 Rosa Ferrentino Luca Vota 《Applied Mathematics》 2021年第5期407-420,共14页
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
关键词 simultaneous equations Model Mathematical Methods Economic Policy Iteratively Reweighted Least Square Abenomics
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SOLUTION OF SIMULTANEOUS EQUATIONS OF COSINE LAW ARISING FROM SUBJECTIVITY GEOMETRY
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作者 云天铨 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1990年第7期631-635,共5页
This paper discusses the solution of a group of two-order six elements rooted algebraic simultaneous equations set up by cosine law arising from the application example of subjectivity geometry[1]. By means of the imp... This paper discusses the solution of a group of two-order six elements rooted algebraic simultaneous equations set up by cosine law arising from the application example of subjectivity geometry[1]. By means of the implicit function theorem, this paper proves that there exists a unique real solution of those equations. Transforming this problem into an unconstrained nonlinear optimization problem, the solution can be found by known methods. 4 numerical example by descent method is given. 展开更多
关键词 SOLUTION OF simultaneous equations OF COSINE LAW ARISING FROM SUBJECTIVITY GEOMETRY
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Household Income and Expenditure Relationships: A Simultaneous Equation Approach
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作者 Nik Hashim Nik Mustapha Noorhaslinda Kulub Abd. Rashid Aslina Nasir 《Chinese Business Review》 2011年第6期395-405,共11页
Income and expenditure are highlighted in this study as they currently affect the quality of life of the Malaysian society. In the Ninth Malaysia Plan (2006-2010) poverty eradication was emphasized as one of the soc... Income and expenditure are highlighted in this study as they currently affect the quality of life of the Malaysian society. In the Ninth Malaysia Plan (2006-2010) poverty eradication was emphasized as one of the socio-economic targets to uplift those poor households from the fast moving modern sectors of the economy. The primary objective of this paper is therefore to identify income and expenditure relationships among the households of the east coast of Peninsular Malaysia during the current economic downturn. Attempts to analyze household consumption as a share of total income and to identify factors contributing to household income and expenditure have become a topic of interest in literature. A substantial portion of household income devoted to productive loans characterizes the majority of Malaysians as the economy progresses to a more advance stage. A significant and strong relationship between income and types of household expenditure is explored from the socio-economic perspectives. Using primary data a system of simultaneous equations, namely the two stage least squares (2SLS) was applied. This paper identifies crucial variables associated with the income and expenditure. Some of these variables showing high correlation with the total expenditure are the housing loan, automobile loan and educational expenditure. 展开更多
关键词 EXPENDITURE INCOME simultaneous two-stage equation method
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Estimating Crash Rate of Freeway Segments Using Simultaneous Equation Model
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作者 Anthony Ramos Hualiang (Harry) Teng Yuyong Fu 《Journal of Transportation Technologies》 2016年第5期327-338,共12页
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
关键词 Weaving Segments Freeways simultaneous equation Models Crash Rate
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Empirical Research on the Relationship between Education Poverty Alleviation and Rural Revitalization—Spatial Panel Simultaneous Equation Model Based on Provincial Panel Data
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作者 Ningning Li Shichang Shen 《Open Journal of Applied Sciences》 2023年第11期2032-2046,共15页
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
关键词 Education Poverty Alleviation Rural Revitalization Entropy Weight Method Space Panel simultaneous equation Model GS3SLS
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Modeling compatible single-tree aboveground biomass equations for masson pine(Pinus massoniana) in southern China 被引量:22
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作者 ZENG Wei-sheng TANG Shou-zheng 《Journal of Forestry Research》 CAS CSCD 2012年第4期593-598,共6页
Because of global climate change, it is necessary to add forest biomass estimation to national forest resource monitoring. The biomass equations developed for forest biomass estimation should be compatible with volume... Because of global climate change, it is necessary to add forest biomass estimation to national forest resource monitoring. The biomass equations developed for forest biomass estimation should be compatible with volume equations. Based on the tree volume and aboveground biomass data of Masson pine (Pinus massoniana Lamb.) in southern China, we constructed one-, two- and three-variable aboveground biomass equations and biomass conversion functions compatible with tree volume equations by using error-in-variable simultaneous equations. The prediction precision of aboveground biomass estimates from one variable equa- tion exceeded 95%. The regressions of aboveground biomass equations were improved slightly when tree height and crown width were used together with diameter on breast height, although the contributions to regressions were statistically insignificant. For the biomass conversion function on one variable, the conversion factor decreased with increasing diameter, but for the conversion function on two variables, the conversion factor increased with increasing diameter but decreased with in- creasing tree height. 展开更多
关键词 aboveground biomass error-in-variable simultaneous equa- tions mean prediction error compatibility Pinus massoniana
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Construction of tree volume equations for Chinese fir plantations in Guizhou Province, southwestern China 被引量:5
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作者 Zhong-Sheng XIA Wei-Sheng ZENG +1 位作者 Song ZHU Hong-Zhang LUO 《Forestry Studies in China》 CAS 2013年第3期179-185,共7页
Forest volume, the major component of forest biomass, is an important issue in forest resource monitoring.It is estimated from tree volume tables or equations. Based on tree volume data of 1840 sample trees from Chine... Forest volume, the major component of forest biomass, is an important issue in forest resource monitoring.It is estimated from tree volume tables or equations. Based on tree volume data of 1840 sample trees from Chinese fir (Cunninghamia lanceolata) plantations in Guizhou Province in southwestern China, parallel one- and two-variable tree volume tables and tree height curves for central and other areas were constructed using an error-in-variable modeling method. The results show that, although the one-variable tree volume equations and height curves between the central and other areas were significantly different, the two-variable volume equations were sufficiently close, so that a generalized two-variable tree volume equation could be established for the entire province. 展开更多
关键词 tree volume two-variable equation one-variable equation error-in-variable modeling method parallel models Chinese fir
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Simultaneous approach for simulation of a high-temperature gas-cooled reactor 被引量:2
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作者 Yang CHEN Jiang-hong YOU Zhi-jiang SHAO Ke-xin WANG Ji-xin QIAN 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2011年第7期567-574,共8页
The simulation of a high-temperature gas-cooled reactor pebble-bed module(HTR-PM) plant is discussed.This lumped parameter model has the form of a set differential algebraic equations(DAEs) that include stiff equation... The simulation of a high-temperature gas-cooled reactor pebble-bed module(HTR-PM) plant is discussed.This lumped parameter model has the form of a set differential algebraic equations(DAEs) that include stiff equations to model point neutron kinetics.The nested approach is the most common method to solve DAE,but this approach is very expensive and time-consuming due to inner iterations.This paper deals with an alternative approach in which a simultaneous solution method is used.The DAEs are discretized over a time horizon using collocation on finite elements,and Radau collocation points are applied.The resulting nonlinear algebraic equations can be solved by existing solvers.The discrete algorithm is discussed in detail;both accuracy and stability issues are considered.Finally,the simulation results are presented to validate the efficiency and accuracy of the simultaneous approach that takes much less time than the nested one. 展开更多
关键词 Differential algebraic equations(DAEs) High-temperature gas-cooled reactor(HTR) SIMULATION simultaneous approach
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On Computer Implementation for Comparison of Inverse Numerical Schemes for Non-Linear Equations 被引量:1
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作者 Mudassir Shams Naila Rafiq +3 位作者 Nazir Ahmad Mir Babar Ahmad Saqib Abbasi Mutee-Ur-Rehman Kayani 《Computer Systems Science & Engineering》 SCIE EI 2021年第3期493-507,共15页
In this research article,we interrogate two new modifications in inverse Weierstrass iterative method for estimating all roots of non-linear equation simultaneously.These modifications enables us to accelerate the con... In this research article,we interrogate two new modifications in inverse Weierstrass iterative method for estimating all roots of non-linear equation simultaneously.These modifications enables us to accelerate the convergence order of inverse Weierstrass method from 2 to 3.Convergence analysis proves that the orders of convergence of the two newly constructed inverse methods are 3.Using computer algebra system Mathematica,we find the lower bound of the convergence order and verify it theoretically.Dynamical planes of the inverse simultaneous methods and classical iterative methods are generated using MATLAB(R2011b),to present the global convergence properties of inverse simultaneous iterative methods as compared to classical methods.Some non-linear models are taken from Physics,Chemistry and engineering to demonstrate the performance and efficiency of the newly constructed methods.Computational CPU time,and residual graphs of the methods are provided to present the dominance behavior of our newly constructed methods as compared to existing inverse and classical simultaneous iterative methods in the literature. 展开更多
关键词 Non-linear equation inverse iterative method simultaneous method basins of attraction lower bound of convergence
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Inverse Estimation on Trigger Factors of Simultaneous Slope Failures with Purification of Training Data Sets
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作者 Hirohito Kojima Ryo Sekine +1 位作者 Tomoya Yoshida Ryo Nozaki 《Journal of Earth Science and Engineering》 2013年第9期594-602,共9页
This paper presents an procedure for purifying training data sets (i.e., past occurrences of slope failures) for inverse estimation on unobserved trigger factors of "different types of simultaneous slope failures"... This paper presents an procedure for purifying training data sets (i.e., past occurrences of slope failures) for inverse estimation on unobserved trigger factors of "different types of simultaneous slope failures". Due to difficulties in pixel-by-pixel observations of trigger factors, as one of the measures, the authors had proposed an inverse analysis algorithm on trigger factors based on SEM (structural equation modeling). Through a measurement equation, the trigger factor is inversely estimated, and a TFI (trigger factor influence) map can be also produced. As a subsequence subject, a purification procedure of training data set should be constructed to improve the accuracy of TFI map which depends on the representativeness of given training data sets of different types of slope failures. The proposed procedure resamples the matched pixels between original groups of past slope failures (i.e., surface slope failures, deep-seated slope failures, landslides) and classified three groups by K-means clustering for all pixels corresponding to those slope failures. For all cases of three types of slope failures, the improvement of success rates with respect to resampled training data sets was confirmed. As a final outcome, the differences between TFI maps produced by using original and resampled training data sets, respectively, are delineated on a DIF map (difference map) which is useful for analyzing trigger factor influence in terms of "risky- and safe-side assessment" sub-areas with respect to "different types of simultaneous slope failures". 展开更多
关键词 Purification of training data simultaneous slope failures inverse analysis of unobserved trigger factor spatial data integration structural equation modeling.
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长江经济带FDI与区域协调发展空间交互影响研究
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作者 金飞 孙攀 《长江流域资源与环境》 北大核心 2025年第3期522-533,共12页
FDI是利用高质量外资的重要抓手,区域协调发展战略是党的十六届三中全会提出的“五个统筹”之一。因此,在国家大力推进高质量发展的背景下,厘清两者之间的关系尤为重要。构建区域协调发展评价指标体系,并采用熵值法测度出其具体数值;基... FDI是利用高质量外资的重要抓手,区域协调发展战略是党的十六届三中全会提出的“五个统筹”之一。因此,在国家大力推进高质量发展的背景下,厘清两者之间的关系尤为重要。构建区域协调发展评价指标体系,并采用熵值法测度出其具体数值;基于1990~2022年长江经济带11个省域的面板数据,采用全域莫兰指数对FDI与区域协调发展的空间自相关性进行检验,在此基础上,运用效应值可分解的空间联立方程模型,探究FDI与区域协调发展之间存在的交互影响。结果表明:(1)FDI与区域协调发展相互促进。(2)FDI与区域协调发展都存在显著的正向空间溢出效应。该文对高水平对外开放背景下利用高质量外资,以及深入推进区域协调发展战略具有重要的理论价值和实践意义。 展开更多
关键词 FDI 区域协调发展 空间联立方程模型 长江经济带
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我国普惠金融发展、共同富裕与政府角色研究
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作者 齐红倩 张佳馨 李宁 《数量经济研究》 2025年第3期1-21,共21页
实现共同富裕需要市场机制和政府干预的有效配合和协调共识。本文基于中国家庭金融调查(CHFS)和宏观经济数据,运用联立方程模型和空间联立方程模型考察政府在普惠金融发展影响共同富裕中的角色与作用。研究发现:不考虑空间影响时,政府... 实现共同富裕需要市场机制和政府干预的有效配合和协调共识。本文基于中国家庭金融调查(CHFS)和宏观经济数据,运用联立方程模型和空间联立方程模型考察政府在普惠金融发展影响共同富裕中的角色与作用。研究发现:不考虑空间影响时,政府扮演着促进普惠金融发展与共同富裕的双角色,并通过支持普惠金融发展间接助力共同富裕;而考虑空间影响后,共同富裕和普惠金融发展表现出空间正向溢出效果,政府干预仍能促进普惠金融发展,但其在实现共同富裕方面则表现为溢出性特征,即相邻地区政府干预有助于本地区共同富裕,验证了“先富带动后富”在实现共同富裕进程中的合理性。因此,现阶段政府与金融部门形成长期生态共识是普惠金融有效实施的保障。 展开更多
关键词 普惠金融 共同富裕 政府干预 市场失灵 联立方程模型
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基于地径的云杉胸径与材积预测模型的构建研究
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作者 刘鹏程 李敏敏 +3 位作者 刘娟 周丹 施德山 李迎美 《林业调查规划》 2025年第2期9-15,共7页
分析采集于云南省丽江、香格里拉和德钦县(市)的150株云杉样木数据,采用平均断面积区分求积法计算样木材积,使用DPS软件的最小二乘法建立云杉胸径一元材积模型、地径一元材积模型和地径一元胸径模型,采用误差变量联立方程组方法建立一... 分析采集于云南省丽江、香格里拉和德钦县(市)的150株云杉样木数据,采用平均断面积区分求积法计算样木材积,使用DPS软件的最小二乘法建立云杉胸径一元材积模型、地径一元材积模型和地径一元胸径模型,采用误差变量联立方程组方法建立一元回归材积模型。结果表明,云杉地径与胸径密切相关,其回归模型的确定系数R^(2)为0.99;地径一元材积模型的预估精度(R^(2)=0.76)明显低于胸径一元材积模型(R^(2)=0.91),采用误差变量联立方程组方法建立的云杉地径—胸径回归材积模型精度(R^(2)=0.92)较直接建立的地径—材积模型高。 展开更多
关键词 材积预测模型 地径一元材积表 胸径—地径回归模型 联立方程组 云杉
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减税激励、地方财政可持续性与经济高质量发展
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作者 常晓素 张雨 《宜宾学院学报》 2025年第1期65-76,共12页
利用2003—2020年284个地级市面板数据,参考熵权topsis法测度经济高质量发展综合指数,基于“有效财政空间”的概念量化地方财政可持续性,构建动态面板联立方程模型,实证考察减税激励、地方财政可持续性与经济高质量发展之间的影响效应... 利用2003—2020年284个地级市面板数据,参考熵权topsis法测度经济高质量发展综合指数,基于“有效财政空间”的概念量化地方财政可持续性,构建动态面板联立方程模型,实证考察减税激励、地方财政可持续性与经济高质量发展之间的影响效应和作用机制,通过标准化回归进一步估计减税激励对经济高质量发展的作用路径并进行效应分解。研究发现:高质量发展指标在0.3625和0.5373间呈现出小幅波动上升的趋势;减税激励和地方财政可持续性均促进经济高质量发展;减税激励通过提高地方政府财政可持续能力间接作用于经济高质量发展;东中部及发达地区减税激励和地方财政可持续性对经济高质量发展的促进作用强于西部及欠发达地区。 展开更多
关键词 减税激励 地方财政可持续性 经济高质量发展 熵权TOPSIS法 动态面板联立方程模型
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Zoeppritz equation-based prestack inversion and its application in fluid identification 被引量:5
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作者 黄捍东 王彦超 +3 位作者 郭飞 张生 纪永祯 刘承汉 《Applied Geophysics》 SCIE CSCD 2015年第2期199-211,275,共14页
Prestack seismic inversion methods adopt approximations of the Zoeppritz equations to describe the relation between reflection coefficients and P-wave velocity, S-wave velocity, and density. However, the error in thes... Prestack seismic inversion methods adopt approximations of the Zoeppritz equations to describe the relation between reflection coefficients and P-wave velocity, S-wave velocity, and density. However, the error in these approximations increases with increasing angle of incidence and variation of the elastic parameters, which increases the number of inversion solutions and minimizes the inversion accuracy. In this study, we explore a method for solving the reflection coefficients by using the Zoeppritz equations. To increase the accuracy of prestack inversion, the simultaneous inversion of P-wave velocity, S-wave velocity, and density by using prestack large-angle seismic data is proposed based on generalized linear inversion theory. Moreover, we reduce the ill posedness and increase the convergence of prestack inversion by using the regularization constraint damping factor and the conjugate gradient algorithm. The proposed prestack inversion method uses prestack large-angle seismic data to obtain accurate seismic elastic parameters that conform to prestack seismic data and are consistent with logging data from wells. 展开更多
关键词 Prestack inversion Zoeppritz equation simultaneous inversion fluid identification
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链主企业数字化转型与碳减排的协同效应 被引量:5
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作者 刘备 张玉凤 彭甲超 《商业研究》 北大核心 2025年第1期79-89,共11页
前沿研究关注企业数字化转型对碳排放的影响,而忽略了碳减排对企业数字化转型的影响效果,更未聚焦链主企业。本文以2010—2022年中国A股上市公司链主企业作为研究对象,采用联立方程模型,结合三阶段最小二乘估计方法(3SLS),探究链主企业... 前沿研究关注企业数字化转型对碳排放的影响,而忽略了碳减排对企业数字化转型的影响效果,更未聚焦链主企业。本文以2010—2022年中国A股上市公司链主企业作为研究对象,采用联立方程模型,结合三阶段最小二乘估计方法(3SLS),探究链主企业数字化转型与碳减排的协同效应及作用机制。研究发现:链主企业数字化转型与碳减排存在协同效应。在制造业和重污染企业中,链主企业数字化转型与碳减排之间的协同效应更明显。影响机制方面,链主企业数字化转型主要通过绿色技术创新效应、供应链管理优化效应和生产率提升效应推动企业降低碳排放,碳减排主要通过政府补贴效应和企业资本更新效应拉动企业进行数字化转型。进一步拓展分析发现,高管环保背景和企业ESG表现在链主企业协同推进数字化转型与实现碳减排目标的进程中扮演重要角色。 展开更多
关键词 链主企业 数字化转型 碳减排 联立方程模型
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基于非线性联立方程系统的杉木生物量动态预测
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作者 付尧 尹晶萍 +2 位作者 许昊 高志雄 马俊杰 《中南林业科技大学学报》 北大核心 2025年第4期151-161,共11页
【目的】森林碳汇是实现“碳中和”战略目标的重要路径之一。准确评估森林生物量的动态变化,对掌握森林碳汇功能,支撑区域战略落地和区域目标实现有着重要的作用。【方法】以福建将乐的杉木Cunninghamia lanceolata为研究对象,通过样地... 【目的】森林碳汇是实现“碳中和”战略目标的重要路径之一。准确评估森林生物量的动态变化,对掌握森林碳汇功能,支撑区域战略落地和区域目标实现有着重要的作用。【方法】以福建将乐的杉木Cunninghamia lanceolata为研究对象,通过样地调查、样木采集、数据整理与分析等方法,利用R语言,基于Logistics生长方程和幂函数结构建立杉木胸径、树高与年龄的理论生长方程和杉木地上、地下以及总生物量与胸径、树高的异速生长方程。在此基础上,利用非线性最小二乘法(NOLS)和非线性似不相关回归(NSUR),构建杉木地上生物量、地下生物量以及总生物量的非线性联立方程系统,并对其进行动态预测研究。【结果】1)基于非线性联立方程系统建立的杉木地上、地下以及总生物量的动态变化模型相较于传统杉木生物量生长模型具有较高的拟合精度,其中,基于NSUR建立的模型较传统模型的平均绝对误差(AME)、剩余均方根误差(RMSE)分别下降30.99%和33.68%,而R^(2)提升了7.78%;2)不同方法的预估能力不同,利用NSUR方法建立的模型相较于NOLS方法的拟合精度和验证精度均更高;3)杉木胸径生长对杉木生物量的异速生长呈现正向影响(协方差值>0),而树高生长对杉木生物量呈现负向影响(协方差值<0)。【结论】基于杉木生长因子的理论生长方程与生物量异速生长方程的非线性联立方程系统能够更好地反映杉木生长与生物量间的复杂关系,本研究建立的模型对开展杉木生物量的动态预测、制定科学合理的经营管理措施具有重要的指导意义。 展开更多
关键词 树木特征因子 理论生长方程 异速生长方程 非线性联立方程系统组 杉木
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“协同共生”还是“此消彼长”:科技金融与新质生产力的空间交互影响研究 被引量:1
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作者 马露瑶 何剑 《财经论丛(浙江财经大学学报)》 北大核心 2025年第8期73-86,共14页
基于2012—2022年我国内地30个省份数据对科技金融与新质生产力进行测度,在此基础上构建空间联立方程模型验证二者的空间交互效应。研究发现,在同一区域内,科技金融与新质生产力相互促进,而在不同区域间二者相互抑制,但这种相互抑制作... 基于2012—2022年我国内地30个省份数据对科技金融与新质生产力进行测度,在此基础上构建空间联立方程模型验证二者的空间交互效应。研究发现,在同一区域内,科技金融与新质生产力相互促进,而在不同区域间二者相互抑制,但这种相互抑制作用在创新型省份建设试点地区和技术市场发展水平高的地区能够被修正。具体来看,在创新型省份建设试点地区,经济主体的创新关注度越高,越有利于形成同一区域内与不同区域间的双向赋能效应;在技术市场发展水平高的地区,知识产权保护力度越强,越有利于形成同一区域内与不同区域间的双向赋能效应。因此,持续推进创新城市建设和提高技术市场发展水平,是实现科技金融与新质生产力双向赋能的必要路径。 展开更多
关键词 科技金融 新质生产力 空间联立方程模型 耦合协调
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双相介质波动方程系数矩阵对称化及其SBP-SAT差分模拟
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作者 孙铖 刘泰玉 +2 位作者 蒋关希曦 张剑伟 杨在林 《振动与冲击》 北大核心 2025年第16期108-118,共11页
波动方程系数矩阵对称化是整合不同类别波动方程、降低波传播模拟难度的有效方法,目前已成功应用于声波方程、各向同性与各向异性介质弹性波动方程。该研究将推导出双项介质波动方程的系数矩阵对称式;随后,引入多轴完全匹配层,采用迎风... 波动方程系数矩阵对称化是整合不同类别波动方程、降低波传播模拟难度的有效方法,目前已成功应用于声波方程、各向同性与各向异性介质弹性波动方程。该研究将推导出双项介质波动方程的系数矩阵对称式;随后,引入多轴完全匹配层,采用迎风格式分部求和-一致逼近项(summation by parts-simultaneous approximation terms,SBP-SAT)有限差分方法离散波动方程,并通过能量法进行稳定性评估。通过数值仿真,表明所提出的离散框架具有整合度高,稳定性好和拓展性强等特点。此外,该方法可以稳定模拟曲线域中的波传播并降低其实现成本,表明了波动方程系数矩阵对称化方法及其离散框架在波传播模拟领域具有广泛的应用前景。 展开更多
关键词 双相介质波动方程 系数矩阵对称式 分部求和-一致逼近项(SBP-SAT) 有限差分方法 能量法
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