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Wang, Ximei
Publications (6 of 6) Show all publications
Bai, C., Kang, Y. & Wang, X. (2021). Spatial Non-Equilibrium and Its Solidification Effect of China's Per Capita Transportation Carbon Emissions. Polish Journal of Environmental Studies, 30(2), 1051-1066
Open this publication in new window or tab >>Spatial Non-Equilibrium and Its Solidification Effect of China's Per Capita Transportation Carbon Emissions
2021 (English)In: Polish Journal of Environmental Studies, ISSN 1230-1485, E-ISSN 2083-5906, Vol. 30, no 2, p. 1051-1066Article in journal (Refereed) Published
Abstract [en]

It is of great significance to understand the spatial non-equilibrium and the solidification degree of transportation carbon emissions, so that differentiated measures can be taken to reduce transportation carbon emissions. Based on China's provincial data from 2005 to 2015, this article uses the Dagum Gini coefficient to decompose the spatial non-equilibrium of per capita transportation carbon emissions from static viewpoint. The results indicate that the overall spatial non-equilibrium shows a significant downward trend; the intensity of transvariation has had an increased contribution rate year by year since 2008, and replaces the inter-regional differences as the main source of the overall spatial non-equilibrium. Next, Kernel density estimation is employed to analyze the evolution laws of spatial non-equilibrium from dynamic viewpoint. The results show that the per capita transportation carbon emissions in the eastern region are successively higher than those at the national level, and in other regions. Meanwhile, some provinces are concentrated at a low level, while others at a high level. Finally, Markov chains approach is applied to identify the solidification effect of the spatial non-equilibrium. The results indicate that the effect is obvious and the state transitions occur only between adjacent types. Moreover, the solidification effects of the provinces with higher per capita transportation carbon emissions are stronger than those provinces with a lower level.

Place, publisher, year, edition, pages
HARD Publishing Company, 2021
Keywords
transportation carbon emissions, spatial non-equilibrium, solidification effect, Dagum Gini coefficient, Kernel density function, Markov chains
National Category
Economics
Identifiers
urn:nbn:se:kth:diva-291957 (URN)10.15244/pjoes/122446 (DOI)000613126000006 ()2-s2.0-85099716025 (Scopus ID)
Note

QC 20210323

Available from: 2021-03-23 Created: 2021-03-23 Last updated: 2022-06-25Bibliographically approved
Wang, X., Hu, M., Zhao, Y. & Djehiche, B. (2020). Credit Scoring Based on the Set-Valued Identification Method. Journal of Systems Science and Complexity, 33(5), 1297-1309
Open this publication in new window or tab >>Credit Scoring Based on the Set-Valued Identification Method
2020 (English)In: Journal of Systems Science and Complexity, ISSN 1009-6124, E-ISSN 1559-7067, Vol. 33, no 5, p. 1297-1309Article in journal (Refereed) Published
Abstract [en]

Credit scoring is one of the key problems in financial risk managements. This paper studies the credit scoring problem based on the set-valued identification method, which is used to explain the relation between the individual attribute vectors and classification for the credit worthy and credit worthless lenders. In particular, system parameters are estimated by the set-valued identification algorithm based on a given recognition criteria. In order to illustrate the efficiency of the proposed method, practical experiments are conducted for credit card applicants of Australia and credit card holders from Taiwan, respectively. The empirical results show that the set-valued model has a higher prediction accuracy on both small and large numbers of data set compared with logistic regression model. Furthermore, parameters estimated by the set-valued identification method are more stable, which provide a meaningful and logical explanation for extracting factors that influence the borrowers’ credit scorings.

Place, publisher, year, edition, pages
Springer Nature, 2020
Keywords
Credit scoring, logistic regression model, prediction accuracy, set-valued model, Logistic regression, Risk management, Attribute vectors, Financial risk management, Identification algorithms, Identification method, Logistic Regression modeling, Parameters estimated, Parameter estimation
National Category
Probability Theory and Statistics
Identifiers
urn:nbn:se:kth:diva-274008 (URN)10.1007/s11424-020-9101-4 (DOI)000558387300001 ()2-s2.0-85083856645 (Scopus ID)
Note

QC 20250314

Available from: 2020-06-29 Created: 2020-06-29 Last updated: 2025-03-14Bibliographically approved
Li, Y., Wang, X., Djehiche, B. & Hu, X. (2020). Credit scoring by incorporating dynamic networked information. European Journal of Operational Research, 286(3), 1103-1112
Open this publication in new window or tab >>Credit scoring by incorporating dynamic networked information
2020 (English)In: European Journal of Operational Research, ISSN 0377-2217, E-ISSN 1872-6860, Vol. 286, no 3, p. 1103-1112Article in journal (Refereed) Published
Abstract [en]

In this paper, the credit scoring problem is studied by incorporating networked information, where the advantages of such incorporation are investigated theoretically in two scenarios. Firstly, a Bayesian optimal filter is proposed to provide risk prediction for lenders assuming that published credit scores are estimated merely from structured financial data. Such prediction can then be used as a monitoring indicator for the risk management in lenders’ future decisions. Secondly, a recursive Bayes estimator is further proposed to improve the precision of credit scoring by incorporating the dynamic interaction topology of clients. It is shown theoretically that under the proposed evolution framework, the designed estimator has a higher precision than any efficient estimator, and the mean square errors are strictly smaller than the Cramér–Rao lower bound for clients within a certain range of scores. Finally, simulation results for a special case illustrate the feasibility and effectiveness of the proposed algorithms.

Place, publisher, year, edition, pages
Elsevier B.V., 2020
Keywords
Bayesian inference, Credit scoring, Decision processes, Multi-agent systems, Networked information, Mean square error, Risk management, Bayes estimator, Dynamic interaction, Efficient estimator, Financial data, Monitoring indicators, Optimal filter, Risk predictions, Risk perception
National Category
Economics and Business Probability Theory and Statistics
Identifiers
urn:nbn:se:kth:diva-274225 (URN)10.1016/j.ejor.2020.03.078 (DOI)000538576200021 ()2-s2.0-85083656541 (Scopus ID)
Note

QC 20200707

Available from: 2020-07-07 Created: 2020-07-07 Last updated: 2024-01-10Bibliographically approved
Wang, X., Djehiche, B. & Hu, X. (2019). Credit rating analysis based on the network of trading information. The journal of network theory in finance, 5(1), 47-65
Open this publication in new window or tab >>Credit rating analysis based on the network of trading information
2019 (English)In: The journal of network theory in finance, ISSN 2055-7795, Vol. 5, no 1, p. 47-65Article in journal (Refereed) Published
Abstract [en]

In this paper, we investigate a credit rating problem based on the network of trading information (NoTI). First, several popular tools, such as assortativity analysis, community detection and centrality measurement, are introduced for analyzing the topology structures and properties of the NoTI. Then, the correlation between the characteristics of the network and the credit ratings is investigated to illustrate the feasibility of credit risk analysis based on the NoTI. Sovereign rating based on the world trade network is analyzed as a case study. The correlation between the centrality metrics and the sovereign ratings conducted by Standard & Poor's clearly shows that highly ranked economies with vigorous economic trading links usually have higher credit ratings. Finally, a simulation is conducted to illustrate the degree of improvement in credit rating prediction accuracy if the NoTI is considered as an additional attribute.

Place, publisher, year, edition, pages
Incisive Media, 2019
Keywords
credit rating, centrality, network, sovereign debt, world trade information
National Category
Mathematics
Identifiers
urn:nbn:se:kth:diva-257666 (URN)10.21314/JNTF.2019.050 (DOI)000480313800003 ()2-s2.0-85073427107 (Scopus ID)
Note

QC 20190904

Available from: 2019-09-04 Created: 2019-09-04 Last updated: 2022-06-26Bibliographically approved
Wang, X., Zhao, Y., Hu, X. & Djehiche, B. (2019). Multi-agent consensus by binary-valued communications of relative state. In: Chinese Control Conference, CCC: . Paper presented at 38th Chinese Control Conference, CCC 2019, 27 July 2019 through 30 July 2019 (pp. 1672-1677). IEEE Computer Society
Open this publication in new window or tab >>Multi-agent consensus by binary-valued communications of relative state
2019 (English)In: Chinese Control Conference, CCC, IEEE Computer Society , 2019, p. 1672-1677Conference paper, Published paper (Refereed)
Abstract [en]

This paper studies an average consensus problem for multi-agent systems (MAS) with binary-valued communications of relative state between neighbors. A two-scale algorithm consisting of 'estimation' stage and 'control' stage is proposed for discrete-time MAS over directed graph. In the 'estimation' stage, the relative states between agents and neighbors are estimated with and without considering measurement noise. In 'control' stage, a distributed control protocol is designed based on the estimations of relative states to achieve average consensus. Convergence and convergence speed of the algorithm are analyzed theoretically under mild conditions. Finally, a numerical simulation is given to validate the developed results of this paper.

Place, publisher, year, edition, pages
IEEE Computer Society, 2019
Keywords
Average consensus, Binary-valued communication, Convergence, Convergence rate, Multi-agent systems, State estimation
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-268406 (URN)10.23919/ChiCC.2019.8865523 (DOI)000621599301126 ()2-s2.0-85074437557 (Scopus ID)
Conference
38th Chinese Control Conference, CCC 2019, 27 July 2019 through 30 July 2019
Note

QC 20200427

Part of ISBN 9789881563972

Available from: 2020-04-27 Created: 2020-04-27 Last updated: 2024-10-24Bibliographically approved
Li, Y., Wang, X., Djehiche, B. & Hu, X.Credit Scoring by Incorporating Dynamic Network Information.
Open this publication in new window or tab >>Credit Scoring by Incorporating Dynamic Network Information
(English)Manuscript (preprint) (Other academic)
Abstract [en]

In this paper,  the credit scoring problem is studied by incorporating network information, where the advantages of such incorporation are investigated in two scenarios. Firstly, a Bayesian optimal filter is proposed to provide a prediction for lenders assuming that published credit scores are estimated merely from structured individual data. Such prediction is used as a monitoring indicator for the risk warning  in lenders' future financial decisions. Secondly, we further propose a recursive Bayes estimator to improve the accuracy of credit scoring estimation by incorporating the dynamic interaction topology of clients as well. It is shown that under the proposed evolution framework, the designed estimator has a higher precision than any efficient estimator, and the mean square errors are strictly smaller than the Cram\'er--Rao lower bound for clients within a certain range of scores. Finally, simulation results for a specific case illustrate the effectiveness and feasibility of the proposed methods.

Keywords
Credit scoring, network information, Bayesian filtering, average risk minimization.
National Category
Mathematics Economics
Research subject
Applied and Computational Mathematics; Economics
Identifiers
urn:nbn:se:kth:diva-252433 (URN)
Note

QC 20190529

Available from: 2019-05-29 Created: 2019-05-29 Last updated: 2022-06-26Bibliographically approved
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