Operational risk events have severely impacted the development of third-party payment(TPP)platforms,and have even led to a discussion on the operational risk capital charge settlement by relevant international regulat...Operational risk events have severely impacted the development of third-party payment(TPP)platforms,and have even led to a discussion on the operational risk capital charge settlement by relevant international regulators.However,prior studies have mostly focused on qualitative mechanism analysis,and have rarely examined quantitative risk assessment based on actual operational risk events.Therefore,this study attempts to assess the operational risk on TPP platforms in China by constructing a systematic framework incorporating database construction and risk modeling.First,the operational risk database that covers 202 events between Q1,2014,and Q2,2020 is constructed.Then,specific causes are clarified,and the characteristics are analyzed from both the trend and loss severity perspectives.Finally,the piecewise-defined severity distribution based-Loss Distribution Approach(PSD-LDA)with double truncation is utilized to assess the operational risk.Two main conclusions are drawn from the empirical analysis.First,legal risk and external fraud risk are the two main causes of operational risk.Second,the yearly Value at Risk and Expected Shortfall are 724.46 million yuan and 1081.98 million yuan under the 99.9%significance level,respectively.Our results are beneficial for both TPP platform operators and regulators in managing and controlling operational risk.展开更多
Mining machineries are generally exposed to intensive vibrations in harsh mining environment. If vibrations are beyond the tolerable limit, the machine and its operator health will be under the risk. In this work, the...Mining machineries are generally exposed to intensive vibrations in harsh mining environment. If vibrations are beyond the tolerable limit, the machine and its operator health will be under the risk. In this work, the vibration of a mining truck at different operational conditions are simulated and discussed. To achieve this aim, three haul roads with low, medium and poor qualities are considered based on the ISO standard. Accordingly, the vibration of a mining truck in different speeds, payload and distribution qualities of materials in the dump body are evaluated in each haul road quality using Trucksim software. The simulation results with statistical discussions indicate that the truck speed and the materials distribution quality have significant effects on the root mean square(RMS) of vertical vibrations. However, the effect of the payload is not considerable on the RMS. Moreover, the accumulation of materials on the rear side of the truck dump body is efficient on the vibrational health risk.展开更多
Currently,the investment of oil and gas industry is still facing an unfavorable environment,in which,instable factors,such as financial crisis,terrorist,religious conflicts and rigorous environmental regulations,keep ...Currently,the investment of oil and gas industry is still facing an unfavorable environment,in which,instable factors,such as financial crisis,terrorist,religious conflicts and rigorous environmental regulations,keep mucking up the business all around the world.Meanwhile,China’s rapid energy consumption growth boosted by a booming economy has put the country to rely heavily on exported oil.It is therefore extremely urgent to expand and diversify petroleum supply channel in consideration of the country’s energy security.As the world’s economy has been slowly recovering from the slump and展开更多
:With the unceasing globalization development of MNCs' business and connnuous intensify in international competition, the managers of MNCs find that the strategy decisions they are faced on are becoming more compli...:With the unceasing globalization development of MNCs' business and connnuous intensify in international competition, the managers of MNCs find that the strategy decisions they are faced on are becoming more complicated, and they have deeply realized that the perception and defense of the international risk has the impact on their strategy decisions. The thesis, proceeding with analyzing and evaluating risk types in the course of enterprises developing in the international markets, based on the integration international risk perception model, utilizing relative theories and study thoughts of the corporate governance mechanisms, especially the relative studies on overseas enterprises' governance mechanisms, explores how to use the corporate governance mechanisms to build the defense system against international risks. Meanwhile, the thesis further discusses the risks our native enterprises have suffered from during the multinational operation in detail, explores its reasons and offers the defense measures of all sorts of risk.展开更多
In this paper, some key problems about operational risk assessment are well analyzed. The time-varying and condition-based component outage model was proposed, which can reflect the changes of weather and other operat...In this paper, some key problems about operational risk assessment are well analyzed. The time-varying and condition-based component outage model was proposed, which can reflect the changes of weather and other operation conditions. A rank enumeration based system state selection method was used to perform risk assessment. Then, the problem of operational risk index was also addressed. In the last part of paper, two groups of numeral tests were presented. The first one showed that the risk assessment results using component instantaneous unavailability, are quite different from the results using steady unavailability, and proves that component outage model with instantaneous unavailability should be used for operational risk assessment; The other one shows that the proposed time-varying component outage model can reflect the operation conditions' influences on the risk assessment results.展开更多
Nowadays with the rapid development of society, remarkable changes have been taken place in city life. The greening construction of the city can not meet the needs of the residents for the good environment. Recently, ...Nowadays with the rapid development of society, remarkable changes have been taken place in city life. The greening construction of the city can not meet the needs of the residents for the good environment. Recently, many large and medium-sized cities across the country have stepped up investment in country park, Its construction provides a good place to alleviate the pressure of life, Short-distance leisure for the city's residents. So it is worth exploring for Gucun Park that how to attract tourists in the fierce competition. The purpose of this paper is to stand in the height of the risk management system, putting forward the corresponding standardized risk response measures, which has great significance to the sustainable operation and development in the future.展开更多
Objective To validate of the Chinese system for cardiac operative risk evaluation (SinoSCORE) in Cantonese surgery patients. Methods Data from Guangdong Cardiovascular Institute in the period January 2004 through Dece...Objective To validate of the Chinese system for cardiac operative risk evaluation (SinoSCORE) in Cantonese surgery patients. Methods Data from Guangdong Cardiovascular Institute in the period January 2004 through December 2008 were analyzed on 2462 Cantonese heart surgery patients. First,compared risk factors of this series and database of SinoSCORE,and then calculated展开更多
To satisfy the requirements of accurate operationalrisk assessment of integrated transmission and distribution networks (I-T&D), an integrated operational risk assessment (IORA) algorithm is proposed. Specific cas...To satisfy the requirements of accurate operationalrisk assessment of integrated transmission and distribution networks (I-T&D), an integrated operational risk assessment (IORA) algorithm is proposed. Specific cases demonstrate thatan I-ORA is necessary because it provides accurate handlingof the coupling between transmission and distribution networks,accurate analysis of power supply mode (PSM) changes ofimportant users and helps to improve security and stability ofpower grid operations. Two key technical requirements in theI-ORA algorithm are realized, i.e., integrated topology analysisand integrated power flow calculation. Under a certain contingency, integrated topology analysis is used to assess the risksof substation power cuts, network split and PSM changes ofimportant users, while the integrated power flow calculation,based on the self-adaptive Levenburg-Marquard method andNewton method, can be implemented to assess risks of heavyload/overload and voltage deviation. In addition, the graphicsprocessing unit is used to parallelly process some computationintensive steps. Numerical experiments show that the proposedI-ORA algorithm can realize accurate assessment for the entireI-T&D. In addition, the efficiency and convergence are satisfying,indicating the proposed I-ORA algorithm can significantly benefitreal practice in the coordination operation of I-T&D in the future.展开更多
Safety is essential when building a strong transportation system.As a key development direction in the global railway system,the intelligent railway has safety at its core,making safety a top priority while pursuing t...Safety is essential when building a strong transportation system.As a key development direction in the global railway system,the intelligent railway has safety at its core,making safety a top priority while pursuing the goals of efficiency,convenience,economy,and environmental friendliness.This paper describes the state of the art and proposes a system architecture for intelligent railway systems.It also focuses on the development of railway safety technology at home and abroad,and proposes the active safety method and technology system based on advanced theoretical methods such as the in-depth integration of cyber–physical systems(CPS),data-driven models,and intelligent computing.Finally,several typical applications are demonstrated to verify the advancement and feasibility of active safety technology in intelligent railway systems.展开更多
Energy storage batteries can smooth the volatility of renewable energy sources.The operating conditions during power grid integration of renewable energy can affect the performance and failure risk of battery energy s...Energy storage batteries can smooth the volatility of renewable energy sources.The operating conditions during power grid integration of renewable energy can affect the performance and failure risk of battery energy storage system(BESS).However,the current modeling of grid-connected BESS is overly simplistic,typically only considering state of charge(SOC)and power constraints.Detailed lithium(Li)-ion battery cell models are computationally intensive and impractical for real-time applications and may not be suitable for power grid operating conditions.Additionally,there is a lack of real-time batteries risk assessment frameworks.To address these issues,in this study,we establish a thermal-electric-performance(TEP)coupling model based on a multitime scale BESS model,incorporating the electrical and thermal characteristics of Li-ion batteries along with their performance degradation to achieve detailed simulation of grid-connected BESS.Additionally,considering the operating characteristics of energy storage batteries and electrical and thermal abuse factors,we developed a battery pack operational riskmodel,which takes into account SOCand charge-discharge rate(Cr),using amodified failure rate to represent the BESS risk.By integrating detailed simulation of energy storage with predictive failure risk analysis,we obtained a detailed model for BESS risk analysis.This model offers a multi-time scale integrated simulation that spans month-level energy storage simulation times,day-level performance degradation,minutescale failure rate,and second-level BESS characteristics.It offers a critical tool for the study of BESS.Finally,the performance and risk of energy storage batteries under three scenarios—microgrid energy storage,wind power smoothing,and power grid failure response—are simulated,achieving a real-time state-dependent operational risk analysis of the BESS.展开更多
A route optimization methodology in the frame of an onboard decision support/guidance system for the ship's master has been developed and is presented in this paper. The method aims at the minimization of the fuel vo...A route optimization methodology in the frame of an onboard decision support/guidance system for the ship's master has been developed and is presented in this paper. The method aims at the minimization of the fuel voyage cost and the risks related to the ship's seakeeping performance expected to be within acceptable limits of voyage duration. Parts of this methodology were implemented by interfacing alternative probability assessment methods, such as Monte Carlo, first order reliability method (FORM) and second order reliability method (SORM), and a 3-D seakeeping code, including a software tool for the calculation of the added resistance in waves of NTUA-SDL. The entire system was integrated within the probabilistic analysis software PROBAN. Two of the main modules for the calculation of added resistance and the probabilistic assessment for the considered seakeeping hazards with respect to exceedance levels of predefined threshold values are herein elaborated and validation studies proved their efficiency in view of their implementation into an on-board optimization system.展开更多
In this paper, the author considers a new Loss-distribution-approach model, in which the over-dispersed operational risks are modeled by the compound negative binomial process. In the single dimensional case, asymptot...In this paper, the author considers a new Loss-distribution-approach model, in which the over-dispersed operational risks are modeled by the compound negative binomial process. In the single dimensional case, asymptotic expansion for the quantile of compound negative binomial process is explored for computing the capital charge of a bank for operational risk. Moreover, when the dependence structure between different risk cells is modeled by the Frank copula, this approach is extended to the multi-dimensional setting. A practical example is given to demonstrate the effectiveness of approximation results.展开更多
The increasing penetration of highly intermittent wind generation could seriously jeopardize the operation reliability of power systems and increase the risk of electricity outages. To this end, this paper proposes a ...The increasing penetration of highly intermittent wind generation could seriously jeopardize the operation reliability of power systems and increase the risk of electricity outages. To this end, this paper proposes a novel data-driven method for operation risk assessment of wind-integrated power systems. Firstly, a new approach is presented to model the uncertainty of wind power in lead time. The proposed approach employs k-means clustering and mixture models(MMs) to construct time-dependent probability distributions of wind power.The proposed approach can also capture the complicated statistical features of wind power such as multimodality. Then, a nonsequential Monte Carlo simulation(NSMCS) technique is adopted to evaluate the operation risk indices. To improve the computation performance of NSMCS, a cross-entropy based importance sampling(CE-IS) technique is applied. The CE-IS technique is modified to include the proposed model of wind power.The method is validated on a modified IEEE 24-bus reliability test system(RTS) and a modified IEEE 3-area RTS while employing the historical data of wind generation. The simulation results verify the importance of accurate modeling of shortterm uncertainty of wind power for operation risk assessment.Further case studies have been performed to analyze the impact of transmission systems on operation risk indices. The computational performance of the framework is also examined.展开更多
Leverage of modem enterprise's financial management includes operating leverage and financial leverage. Both of them exist objectively, are not changeable with human's minds. They enlarge enterprise's benefit and r...Leverage of modem enterprise's financial management includes operating leverage and financial leverage. Both of them exist objectively, are not changeable with human's minds. They enlarge enterprise's benefit and risk, so they have both positive and negative effects. The degrees of them are measured as DOL and DFL. In financial management, the relationship between DOL and operating risk has regularity in quantity, and so does the relationship between DFL and financial risk.展开更多
Background It is still unclear whether pulmonary function tests (PFTs) are sufficient for predicting perioperative risk,and whether all patients or only a subset of them need a cardiopulmonary exercise test (CPET)...Background It is still unclear whether pulmonary function tests (PFTs) are sufficient for predicting perioperative risk,and whether all patients or only a subset of them need a cardiopulmonary exercise test (CPET) for further assessment.Thus, this study was designed to evaluate the CPET and compare the results of CPET and conventional PFTs to identify which parameters are more reliable and valuable in predicting perioperative risks for high risk patients with lung cancer.Methods From January 2005 to August 2008, 297 consecutive lung cancer patients underwent conventional PFTs (spirometry + single-breath carbon monoxide diffusing capacity of the lungs (DLCOsb) for diffusion capacity) and CPET preoperatively. The correlation of postoperative cardiopulmonary complications with the parameters of PFT and CPET was retrospectively analyzed using the chi-square test, independent sample t test and binary Logistic regression analysis.Results Of the 297 patients, 78 did not receive operation due to advanced disease stage or poor cardiopulmonary function. The remaining 219 underwent different modes of operations. Twenty-one cases were excluded from this study due to exploration alone (15 cases) and operation-related complications (6 cases). Thus, 198 cases were eligible for evaluation. Fifty of the 198 patients (25.2%) had postoperative cardiopulmonary complications. Three patients (1.5%)died of complications within 30 postoperative days. The patients were stratified into groups based on VO2max/pred respectively. The rate of postoperative cardiopulmonary complications was significantly higher in the group with cardiopulmonary complications were significantly correlated with age, comorbidities, and poor PFT and CPET results.used to stratify the patients' cardiopulmonary function status and to predict the risk of postoperative cardiopulmonary predicting perioperative risk. If available, cardiopulmonary exercise testing is strongly suggested for high-risk lung cancer patients in addition to conventional pulmonary function tests, and both should be combined to assess cardiopulmonary function status.展开更多
Background The European System for Cardiac Operative Risk Evaluation (EuroSCORE) is one of the most widely used risk models for the predicting mortality after cardiac surgery. The aim of this study was to validate t...Background The European System for Cardiac Operative Risk Evaluation (EuroSCORE) is one of the most widely used risk models for the predicting mortality after cardiac surgery. The aim of this study was to validate the EuroSCORE model for predicting operative mortality in heart valve surgery on a Chinese multicenter database and comparing the performance of EuroSCORE with our new risk stratification system, the Sino System for Coronary Operative Risk Evaluation (SinoSCORE). Methods Data from patients undergoing heart valve surgery between January 2007 and December 2008 were retrospectively collected, from 43 hospitals in China. The EuroSCORE and the SinoSCORE were calculated for each patient. Mortality was defined as any in-hospital death. Area under the receiver operating characteristics curve (AUC) was used to study the discriminatory abilities of the models. The Hosmer-Lemeshow (H-L) goodness-of-fit test was used to study the calibration of the predictive models. Results A total of 15 367 patients were analyzed. For the entire cohort, the observed mortality was 2.34%, the predicted mortality was 3.71% (additive), 3.19% (logistic) and 3.66% (SinoSCORE). AUC was 0.747 for SinoSCORE, 0.699 additive and 0.696 for logistic EuroSCORE. Calibration of SinoSCORE and additive EuroSCORE was good (H-L: P=-0.250 and P=0.051, respectively), but the logistic EuroSCORE model had a poor calibration (H-L: P〈0.05). The discriminatory ability and calibration of the SinoSCORE were good in low- and high-risk patients, However, the discriminatory ability of the EuroSCORE model was poor in all risk deciles. Conclusions The EuroSCORE does not accurately predict mortality in Chinese patients with heart valve surgery, and the SinoSCORE is superior to the EuroSCORE at predicting in-hospital mortality in Chinese heart valve surgery patients.展开更多
This article provides a brief description of the fire space monitoring system in Kazakhstan, including the GIS-technology incorporated in its structure. The system performs operative space monitoring of fire areas and...This article provides a brief description of the fire space monitoring system in Kazakhstan, including the GIS-technology incorporated in its structure. The system performs operative space monitoring of fire areas and burnt areas, mapping of large fire areas, analysis of seasonal and long-term dynamics of burnt areas, and estimation of fire risk zones. Examples of output information obtained from space monitoring of fires are given. Possible directions of development of fire space monitoring in Kazakhstan are specified.展开更多
The bullwhip effect is w idely found in business and exerts adverse effects on business activities.To investigate the influence of the bullwhip effect on firm s'performance and their responses,this study proposed ...The bullwhip effect is w idely found in business and exerts adverse effects on business activities.To investigate the influence of the bullwhip effect on firm s'performance and their responses,this study proposed an environment-behavior-performance analysis fram ework and offered a new perspective for studying the bullwhip effect.Using data collected from 1,734 listed manufacturers in China from 2002 to 2017,we adopted regression models to test the proposed m odel and conducted a series of robustness tests.We find that the bullwhip effect is positively related to operating risk,inventory,and cash holdings,and the moderate levels of inventory and cash are negatively associated with operating risk.Specifically,inventory and cash play different roles and work together to alleviate operating risk induced by the bullwhip effect.However,excess resource holdings are positively associated with operating risk.Therefore,firm swith different levels of resources should hold suitable levels of inventory,cash,or both as contingent responses to the bullwhip effect.展开更多
基金supported by grants from the National Natural Science Foundation of China(71425002,72101166)the Capital University of Economics and Business for the Fundamental Research Funds for Universities affiliated to Beijing(XRZ2021066).
文摘Operational risk events have severely impacted the development of third-party payment(TPP)platforms,and have even led to a discussion on the operational risk capital charge settlement by relevant international regulators.However,prior studies have mostly focused on qualitative mechanism analysis,and have rarely examined quantitative risk assessment based on actual operational risk events.Therefore,this study attempts to assess the operational risk on TPP platforms in China by constructing a systematic framework incorporating database construction and risk modeling.First,the operational risk database that covers 202 events between Q1,2014,and Q2,2020 is constructed.Then,specific causes are clarified,and the characteristics are analyzed from both the trend and loss severity perspectives.Finally,the piecewise-defined severity distribution based-Loss Distribution Approach(PSD-LDA)with double truncation is utilized to assess the operational risk.Two main conclusions are drawn from the empirical analysis.First,legal risk and external fraud risk are the two main causes of operational risk.Second,the yearly Value at Risk and Expected Shortfall are 724.46 million yuan and 1081.98 million yuan under the 99.9%significance level,respectively.Our results are beneficial for both TPP platform operators and regulators in managing and controlling operational risk.
文摘Mining machineries are generally exposed to intensive vibrations in harsh mining environment. If vibrations are beyond the tolerable limit, the machine and its operator health will be under the risk. In this work, the vibration of a mining truck at different operational conditions are simulated and discussed. To achieve this aim, three haul roads with low, medium and poor qualities are considered based on the ISO standard. Accordingly, the vibration of a mining truck in different speeds, payload and distribution qualities of materials in the dump body are evaluated in each haul road quality using Trucksim software. The simulation results with statistical discussions indicate that the truck speed and the materials distribution quality have significant effects on the root mean square(RMS) of vertical vibrations. However, the effect of the payload is not considerable on the RMS. Moreover, the accumulation of materials on the rear side of the truck dump body is efficient on the vibrational health risk.
文摘Currently,the investment of oil and gas industry is still facing an unfavorable environment,in which,instable factors,such as financial crisis,terrorist,religious conflicts and rigorous environmental regulations,keep mucking up the business all around the world.Meanwhile,China’s rapid energy consumption growth boosted by a booming economy has put the country to rely heavily on exported oil.It is therefore extremely urgent to expand and diversify petroleum supply channel in consideration of the country’s energy security.As the world’s economy has been slowly recovering from the slump and
基金This research was supported by the National Social Science Foundation of China, and its approval number is 03CJY011
文摘:With the unceasing globalization development of MNCs' business and connnuous intensify in international competition, the managers of MNCs find that the strategy decisions they are faced on are becoming more complicated, and they have deeply realized that the perception and defense of the international risk has the impact on their strategy decisions. The thesis, proceeding with analyzing and evaluating risk types in the course of enterprises developing in the international markets, based on the integration international risk perception model, utilizing relative theories and study thoughts of the corporate governance mechanisms, especially the relative studies on overseas enterprises' governance mechanisms, explores how to use the corporate governance mechanisms to build the defense system against international risks. Meanwhile, the thesis further discusses the risks our native enterprises have suffered from during the multinational operation in detail, explores its reasons and offers the defense measures of all sorts of risk.
基金supported in part by Special Fund of the National Priority Basic Research of China(No.2004CB217908)National Science Foundation of China(No.50?07013).
文摘In this paper, some key problems about operational risk assessment are well analyzed. The time-varying and condition-based component outage model was proposed, which can reflect the changes of weather and other operation conditions. A rank enumeration based system state selection method was used to perform risk assessment. Then, the problem of operational risk index was also addressed. In the last part of paper, two groups of numeral tests were presented. The first one showed that the risk assessment results using component instantaneous unavailability, are quite different from the results using steady unavailability, and proves that component outage model with instantaneous unavailability should be used for operational risk assessment; The other one shows that the proposed time-varying component outage model can reflect the operation conditions' influences on the risk assessment results.
文摘Nowadays with the rapid development of society, remarkable changes have been taken place in city life. The greening construction of the city can not meet the needs of the residents for the good environment. Recently, many large and medium-sized cities across the country have stepped up investment in country park, Its construction provides a good place to alleviate the pressure of life, Short-distance leisure for the city's residents. So it is worth exploring for Gucun Park that how to attract tourists in the fierce competition. The purpose of this paper is to stand in the height of the risk management system, putting forward the corresponding standardized risk response measures, which has great significance to the sustainable operation and development in the future.
文摘Objective To validate of the Chinese system for cardiac operative risk evaluation (SinoSCORE) in Cantonese surgery patients. Methods Data from Guangdong Cardiovascular Institute in the period January 2004 through December 2008 were analyzed on 2462 Cantonese heart surgery patients. First,compared risk factors of this series and database of SinoSCORE,and then calculated
基金the State Grid Zhejiang Electric Power Co.,Ltd.(Science and Technology Project under Grant 5211JH180081:Research on security evaluation and control technology of smart platform based on dispatch cloud.)。
文摘To satisfy the requirements of accurate operationalrisk assessment of integrated transmission and distribution networks (I-T&D), an integrated operational risk assessment (IORA) algorithm is proposed. Specific cases demonstrate thatan I-ORA is necessary because it provides accurate handlingof the coupling between transmission and distribution networks,accurate analysis of power supply mode (PSM) changes ofimportant users and helps to improve security and stability ofpower grid operations. Two key technical requirements in theI-ORA algorithm are realized, i.e., integrated topology analysisand integrated power flow calculation. Under a certain contingency, integrated topology analysis is used to assess the risksof substation power cuts, network split and PSM changes ofimportant users, while the integrated power flow calculation,based on the self-adaptive Levenburg-Marquard method andNewton method, can be implemented to assess risks of heavyload/overload and voltage deviation. In addition, the graphicsprocessing unit is used to parallelly process some computationintensive steps. Numerical experiments show that the proposedI-ORA algorithm can realize accurate assessment for the entireI-T&D. In addition, the efficiency and convergence are satisfying,indicating the proposed I-ORA algorithm can significantly benefitreal practice in the coordination operation of I-T&D in the future.
基金supported by the 2021 Chinese Academy of Engineering(CAE)International Top-level Forum on Engineering Science and Technology,“Safety and Governance of the High-Speed Railway”。
文摘Safety is essential when building a strong transportation system.As a key development direction in the global railway system,the intelligent railway has safety at its core,making safety a top priority while pursuing the goals of efficiency,convenience,economy,and environmental friendliness.This paper describes the state of the art and proposes a system architecture for intelligent railway systems.It also focuses on the development of railway safety technology at home and abroad,and proposes the active safety method and technology system based on advanced theoretical methods such as the in-depth integration of cyber–physical systems(CPS),data-driven models,and intelligent computing.Finally,several typical applications are demonstrated to verify the advancement and feasibility of active safety technology in intelligent railway systems.
基金Supported by Open Fund of National Key Laboratory of Power Grid Safety(No.XTB51202301386).
文摘Energy storage batteries can smooth the volatility of renewable energy sources.The operating conditions during power grid integration of renewable energy can affect the performance and failure risk of battery energy storage system(BESS).However,the current modeling of grid-connected BESS is overly simplistic,typically only considering state of charge(SOC)and power constraints.Detailed lithium(Li)-ion battery cell models are computationally intensive and impractical for real-time applications and may not be suitable for power grid operating conditions.Additionally,there is a lack of real-time batteries risk assessment frameworks.To address these issues,in this study,we establish a thermal-electric-performance(TEP)coupling model based on a multitime scale BESS model,incorporating the electrical and thermal characteristics of Li-ion batteries along with their performance degradation to achieve detailed simulation of grid-connected BESS.Additionally,considering the operating characteristics of energy storage batteries and electrical and thermal abuse factors,we developed a battery pack operational riskmodel,which takes into account SOCand charge-discharge rate(Cr),using amodified failure rate to represent the BESS risk.By integrating detailed simulation of energy storage with predictive failure risk analysis,we obtained a detailed model for BESS risk analysis.This model offers a multi-time scale integrated simulation that spans month-level energy storage simulation times,day-level performance degradation,minutescale failure rate,and second-level BESS characteristics.It offers a critical tool for the study of BESS.Finally,the performance and risk of energy storage batteries under three scenarios—microgrid energy storage,wind power smoothing,and power grid failure response—are simulated,achieving a real-time state-dependent operational risk analysis of the BESS.
基金supported by DNV in the framework of the GIFT strategic R&D collaboration agreement between DNV and the School of Naval Architecture and Marine Engineering of NTUA-Ship Design Laboratory
文摘A route optimization methodology in the frame of an onboard decision support/guidance system for the ship's master has been developed and is presented in this paper. The method aims at the minimization of the fuel voyage cost and the risks related to the ship's seakeeping performance expected to be within acceptable limits of voyage duration. Parts of this methodology were implemented by interfacing alternative probability assessment methods, such as Monte Carlo, first order reliability method (FORM) and second order reliability method (SORM), and a 3-D seakeeping code, including a software tool for the calculation of the added resistance in waves of NTUA-SDL. The entire system was integrated within the probabilistic analysis software PROBAN. Two of the main modules for the calculation of added resistance and the probabilistic assessment for the considered seakeeping hazards with respect to exceedance levels of predefined threshold values are herein elaborated and validation studies proved their efficiency in view of their implementation into an on-board optimization system.
基金supported by the National Natural Science Foundation of China under Grant No.11201001 in partthe Science Research Grant of Shaanxi Province under Grant No.2011JM1019the Foundation Research Project of Engineering University of CAPF under Grant No.WJY201304
文摘In this paper, the author considers a new Loss-distribution-approach model, in which the over-dispersed operational risks are modeled by the compound negative binomial process. In the single dimensional case, asymptotic expansion for the quantile of compound negative binomial process is explored for computing the capital charge of a bank for operational risk. Moreover, when the dependence structure between different risk cells is modeled by the Frank copula, this approach is extended to the multi-dimensional setting. A practical example is given to demonstrate the effectiveness of approximation results.
基金supported in part by the Natural Sciences and Engineering Research Council (NSERC) of Canadathe Saskatchewan Power Corporation(SaskPower)。
文摘The increasing penetration of highly intermittent wind generation could seriously jeopardize the operation reliability of power systems and increase the risk of electricity outages. To this end, this paper proposes a novel data-driven method for operation risk assessment of wind-integrated power systems. Firstly, a new approach is presented to model the uncertainty of wind power in lead time. The proposed approach employs k-means clustering and mixture models(MMs) to construct time-dependent probability distributions of wind power.The proposed approach can also capture the complicated statistical features of wind power such as multimodality. Then, a nonsequential Monte Carlo simulation(NSMCS) technique is adopted to evaluate the operation risk indices. To improve the computation performance of NSMCS, a cross-entropy based importance sampling(CE-IS) technique is applied. The CE-IS technique is modified to include the proposed model of wind power.The method is validated on a modified IEEE 24-bus reliability test system(RTS) and a modified IEEE 3-area RTS while employing the historical data of wind generation. The simulation results verify the importance of accurate modeling of shortterm uncertainty of wind power for operation risk assessment.Further case studies have been performed to analyze the impact of transmission systems on operation risk indices. The computational performance of the framework is also examined.
文摘Leverage of modem enterprise's financial management includes operating leverage and financial leverage. Both of them exist objectively, are not changeable with human's minds. They enlarge enterprise's benefit and risk, so they have both positive and negative effects. The degrees of them are measured as DOL and DFL. In financial management, the relationship between DOL and operating risk has regularity in quantity, and so does the relationship between DFL and financial risk.
文摘Background It is still unclear whether pulmonary function tests (PFTs) are sufficient for predicting perioperative risk,and whether all patients or only a subset of them need a cardiopulmonary exercise test (CPET) for further assessment.Thus, this study was designed to evaluate the CPET and compare the results of CPET and conventional PFTs to identify which parameters are more reliable and valuable in predicting perioperative risks for high risk patients with lung cancer.Methods From January 2005 to August 2008, 297 consecutive lung cancer patients underwent conventional PFTs (spirometry + single-breath carbon monoxide diffusing capacity of the lungs (DLCOsb) for diffusion capacity) and CPET preoperatively. The correlation of postoperative cardiopulmonary complications with the parameters of PFT and CPET was retrospectively analyzed using the chi-square test, independent sample t test and binary Logistic regression analysis.Results Of the 297 patients, 78 did not receive operation due to advanced disease stage or poor cardiopulmonary function. The remaining 219 underwent different modes of operations. Twenty-one cases were excluded from this study due to exploration alone (15 cases) and operation-related complications (6 cases). Thus, 198 cases were eligible for evaluation. Fifty of the 198 patients (25.2%) had postoperative cardiopulmonary complications. Three patients (1.5%)died of complications within 30 postoperative days. The patients were stratified into groups based on VO2max/pred respectively. The rate of postoperative cardiopulmonary complications was significantly higher in the group with cardiopulmonary complications were significantly correlated with age, comorbidities, and poor PFT and CPET results.used to stratify the patients' cardiopulmonary function status and to predict the risk of postoperative cardiopulmonary predicting perioperative risk. If available, cardiopulmonary exercise testing is strongly suggested for high-risk lung cancer patients in addition to conventional pulmonary function tests, and both should be combined to assess cardiopulmonary function status.
文摘Background The European System for Cardiac Operative Risk Evaluation (EuroSCORE) is one of the most widely used risk models for the predicting mortality after cardiac surgery. The aim of this study was to validate the EuroSCORE model for predicting operative mortality in heart valve surgery on a Chinese multicenter database and comparing the performance of EuroSCORE with our new risk stratification system, the Sino System for Coronary Operative Risk Evaluation (SinoSCORE). Methods Data from patients undergoing heart valve surgery between January 2007 and December 2008 were retrospectively collected, from 43 hospitals in China. The EuroSCORE and the SinoSCORE were calculated for each patient. Mortality was defined as any in-hospital death. Area under the receiver operating characteristics curve (AUC) was used to study the discriminatory abilities of the models. The Hosmer-Lemeshow (H-L) goodness-of-fit test was used to study the calibration of the predictive models. Results A total of 15 367 patients were analyzed. For the entire cohort, the observed mortality was 2.34%, the predicted mortality was 3.71% (additive), 3.19% (logistic) and 3.66% (SinoSCORE). AUC was 0.747 for SinoSCORE, 0.699 additive and 0.696 for logistic EuroSCORE. Calibration of SinoSCORE and additive EuroSCORE was good (H-L: P=-0.250 and P=0.051, respectively), but the logistic EuroSCORE model had a poor calibration (H-L: P〈0.05). The discriminatory ability and calibration of the SinoSCORE were good in low- and high-risk patients, However, the discriminatory ability of the EuroSCORE model was poor in all risk deciles. Conclusions The EuroSCORE does not accurately predict mortality in Chinese patients with heart valve surgery, and the SinoSCORE is superior to the EuroSCORE at predicting in-hospital mortality in Chinese heart valve surgery patients.
文摘This article provides a brief description of the fire space monitoring system in Kazakhstan, including the GIS-technology incorporated in its structure. The system performs operative space monitoring of fire areas and burnt areas, mapping of large fire areas, analysis of seasonal and long-term dynamics of burnt areas, and estimation of fire risk zones. Examples of output information obtained from space monitoring of fires are given. Possible directions of development of fire space monitoring in Kazakhstan are specified.
基金the National Key R&D Program of China,under grant No.2019YFB1404901the National Natural Science Foundation of China(NSFC),under Grants No.71821002,No.72091214 and No.71602171.
文摘The bullwhip effect is w idely found in business and exerts adverse effects on business activities.To investigate the influence of the bullwhip effect on firm s'performance and their responses,this study proposed an environment-behavior-performance analysis fram ework and offered a new perspective for studying the bullwhip effect.Using data collected from 1,734 listed manufacturers in China from 2002 to 2017,we adopted regression models to test the proposed m odel and conducted a series of robustness tests.We find that the bullwhip effect is positively related to operating risk,inventory,and cash holdings,and the moderate levels of inventory and cash are negatively associated with operating risk.Specifically,inventory and cash play different roles and work together to alleviate operating risk induced by the bullwhip effect.However,excess resource holdings are positively associated with operating risk.Therefore,firm swith different levels of resources should hold suitable levels of inventory,cash,or both as contingent responses to the bullwhip effect.