Background:Agarwood,primarily derived from the Aquilaria and Gyrinops genera,holds significant economic importance.However,there is a lack of comprehensive investigations providing guidance to importing nations regard...Background:Agarwood,primarily derived from the Aquilaria and Gyrinops genera,holds significant economic importance.However,there is a lack of comprehensive investigations providing guidance to importing nations regarding cultivation quantities and expected yields of Agarwood from distinct species.This study aims to address this gap by exploring the historical context and trade evolution of Agarwood,highlighting its global importance,and the challenges associated with securing accurate species information.Method:On-site visits to Agarwood cultivation sites were conducted to gain a nuanced understanding of Aquilaria species and their cultivation requirements.Additionally,a thorough analysis of global export and import data for Agarwood products over the last decade was undertaken.Results:China Mainland emerged as the leading exporter of Agarwood,averaging an annual export value of USD 1 million.India’s substantial exports challenge the prevailing notion of limited Agarwood production within its borders.Hong Kong and Singapore are pivotal distribution hubs,while Hong Kong and Taipei feature prominently as import destinations.Our analysis uncovers anomalies in the representation of Agarwood producers from 2001 to 2008,suggesting potential misclassification of Aquilaria Agarwood as Gyrinops in global export information.These findings underscore the urgency of investigating classification and reporting practices in the Agarwood trade.Furthermore,A.filaria emerges as a notable source,while A.malaccensis is decline in prominence.Conclusion:This study provides crucial insights for policymakers,stakeholders,and industry players seeking to make informed decisions in the Agarwood trade landscape.The results highlight the need for accurate species identification,classification,and reporting practices to ensure sustainable cultivation and trade of Agarwood.展开更多
In a system of systems(SoS),resilience is an important factor in maintaining the functionality,stability,and enhancing the operation effectiveness.From the perspective of resilience,this paper studies the importance o...In a system of systems(SoS),resilience is an important factor in maintaining the functionality,stability,and enhancing the operation effectiveness.From the perspective of resilience,this paper studies the importance of the SoS,and a resilience-based importance measure analysis is conducted to provide suggestions in the design and optimization of the structure of the SoS.In this paper,the components of the SoS are simplified as four kinds of network nodes:sensor,decision point,influencer,and target.In this networked SoS,the number of operation loops is used as the performance indicator,and an approximate algorithm,which is based on eigenvalue of the adjacency matrix,is proposed to calculate the number of operation loops.In order to understand the performance change of the SoS during the attack and defense process in the operations,an integral resilience model is proposed to depict the resilience of the SoS.From different perspectives of enhancing the resilience,different measures,parameters and the corresponding algorithms for the resilience importance of components are proposed.Finally,a case study on an SoS is conducted to verify the validity of the network modelling and the resiliencebased importance analysis method.展开更多
The importance analysis method represents a powerful tool for quantifying the impact of input uncertainty on the output uncertainty.When an input variable is described by a specific interval rather than a certain prob...The importance analysis method represents a powerful tool for quantifying the impact of input uncertainty on the output uncertainty.When an input variable is described by a specific interval rather than a certain probability distribution,the interval importance measure of input interval variable can be calculated by the traditional non-probabilistic importance analysis methods.Generally,the non-probabilistic importance analysis methods involve the Monte Carlo simulation(MCS)and the optimization-based methods,which both have high computational cost.In order to overcome this problem,this study proposes an interval important analytical method avoids the time-consuming optimization process.First,the original performance function is decomposed into a combination of a series of one-dimensional subsystems.Next,the interval of each variable is divided into several subintervals,and the response value of each one-dimensional subsystem at a specific input point is calculated.Then,the obtained responses are taken as specific values of the new input variable,and the interval importance is calculated by the approximated performance function.Compared with the traditional non-probabilistic importance analysis method,the proposed method significantly reduces the computational cost caused by the MCS and optimization process.In the proposed method,the number of function evaluations is equal to one plus the sum of the subintervals of all of the variables.The efficiency and accuracy of the proposed method are verified by five examples.The results show that the proposed method is not only efficient but also accurate.展开更多
Importance analysis quantifies the critical degree of individual component. Compared with the traditional binary state system,importance analysis of the multi-state system is more aligned with the practice. Because th...Importance analysis quantifies the critical degree of individual component. Compared with the traditional binary state system,importance analysis of the multi-state system is more aligned with the practice. Because the multi-valued decision diagram( MDD) can reflect the relationship between the components and the system state bilaterally, it was introduced into the reliability calculation of the multi-state system( MSS). The building method,simplified criteria,and path search and probability algorithm of MSS structure function MDD were given,and the reliability of the system was calculated. The computing methods of importance based on MDD and direct partial logic derivatives( DPLD) were presented. The diesel engine fuel supply system was taken as an example to illustrate the proposed method. The results show that not only the probability of the system in each state can be easily obtained,but also the influence degree of each component and its state on the system reliability can be obtained,which is conducive to the condition monitoring and structure optimization of the system.展开更多
For the best dynamic performance of a co-cured composite damping instrument panel with light weight and high strength, a multilayer sandwich structure with polymethaerylimide (PMI) foam combined with embedded and co...For the best dynamic performance of a co-cured composite damping instrument panel with light weight and high strength, a multilayer sandwich structure with polymethaerylimide (PMI) foam combined with embedded and co-cured composite damping structure is proposed. The struetue can maintain the excellent mechanical properties of composite materials, and achieve the damping and light effect at the same time. Input variables which may affect the dynamic performance of the instrument panel were selected and variance based importance measure was analyzed through multi- finite element method (FEM) analysis. Using the results of the importance measure analysis, with other design requirements, the important design variable was optimized and an instrument panel with the best dynamic performance under the requirements of light weight and high strength was obtained. The structure of the instrument panel can provide reference for the design of precision, high speed, and dynamic composite component. The importance measure analysis of dynamic performance of the instrument panel can provide a reference for relative design.展开更多
With the trade network analysis method and bilateral country-product level trade data of 2017-2020,this paper reveals the overall characteristics and intrinsic vulnerabilities of China’s global supply chains.Our rese...With the trade network analysis method and bilateral country-product level trade data of 2017-2020,this paper reveals the overall characteristics and intrinsic vulnerabilities of China’s global supply chains.Our research finds that first,most global supply-chain-vulnerable products are from technology-intensive sectors.For advanced economies,their supply chain vulnerabilities are primarily exposed to political and economic alliances.In comparison,developing economies are more dependent on regional communities.Second,China has a significant export advantage with over 80%of highly vulnerable intermediate inputs relying on imports of high-end electrical,mechanical and chemical products from advanced economies or their multinational companies.China also relies on developing economies for the import of some resource products.Third,during the trade frictions from 2018 to 2019 and the subsequent COVID-19 pandemic,there was a significant reduction in the supply chain vulnerabilities of China and the US for critical products compared with other products,which reflects a shift in the layout of critical product supply chains to ensure not just efficiency but security.China should address supply chain vulnerabilities by bolstering supply-side weaknesses,diversifying import sources,and promoting international coordination and cooperation.展开更多
National logistics system in Indonesia can be categorized as inefficient logistics system due to current number of non-value added (NVA) activities. The unreliable National logistics system and the complexity of dis...National logistics system in Indonesia can be categorized as inefficient logistics system due to current number of non-value added (NVA) activities. The unreliable National logistics system and the complexity of distribution system are the big obstacles. This study aims to analyze the value and to propose recommendation for further improvement of National distribution system for imported product. This study employed convenience sampling through in-depth interview to analyze the activity in freight forwarder (FF), distributor and retailer. To demonstrate and analyze the activity process in each party, Process Activity Mapping (PAM) was used as a tool. The study results showed that the delivery speed in Jakarta (8.4 min/km) is slower than that of Surabaya (6.6 min/km). The government support through creating adequate infrastructure, good bureaucracy system and good collaboration directly affects the activities of FF, distributor and retailer. Improving FF performance in a timely and reliable manner is required to reduce errors that may occur. Moreover, encouraging the practice of cold chain management is also necessary in distributing the product throughout Indonesia. The pull strategy can be chosen by retailer to eliminate storage activity. Meanwhile, the use of information technology (IT) system is essential to encourage better inventory management, database management and sharing information in distributor and retailer stage.展开更多
4. Increasing import of rare earth resources products As a big producer and an important export country of rare earth products for years, rare earths import is in an auxiliary position in China. Import volume is rathe...4. Increasing import of rare earth resources products As a big producer and an important export country of rare earth products for years, rare earths import is in an auxiliary position in China. Import volume is rather small. However, since the strengthened macro control measures展开更多
Problems existed in the import & export of Chinese rare earths in 2006 Although it was holistically stable on the export of Chinese rare earth products, there were some problems that are reflected in the following...Problems existed in the import & export of Chinese rare earths in 2006 Although it was holistically stable on the export of Chinese rare earth products, there were some problems that are reflected in the following aspects:展开更多
The situation of intercepted weeds from wooI in Jiangsu port during 2004 to 2012 was introduced in this paper, and the corresponding countermeasures were then proposed. The resuIts showed that a total of 38 famiIies, ...The situation of intercepted weeds from wooI in Jiangsu port during 2004 to 2012 was introduced in this paper, and the corresponding countermeasures were then proposed. The resuIts showed that a total of 38 famiIies, 138 genera, 268 species and 13 868 species-times of weeds were intercepted, incIuding 3 famiIies, 11 genera, 20 species and 2 094 species-times of quarantine weeds. The weeds were intercepted from the wooI introduced from 19 countries and regions, among which, Australia had the highest species-times, accounting for 71.0% of the total. Bases on the analysis of interception situation of weeds, some countermeasures were pro-posed from the perspectives of risk assessment, quarantine supervision, quarantine treatment and epidemic surveiI ance, providing some reference for estabIishing a perfect system for preventing the invasion of exotic weeds.展开更多
In structural reliability analysis,simulation methods are widely used.The statistical characteristics of failure probability estimate of these methods have been well investigated.In this study,the sensitivities of the...In structural reliability analysis,simulation methods are widely used.The statistical characteristics of failure probability estimate of these methods have been well investigated.In this study,the sensitivities of the failure probability estimate and its statistical characteristics with regard to sample,called‘contribution indexes’,are proposed to measure the contribution of sample.The contribution indexes in four widely simulation methods,i.e.,Monte Carlo simulation(MCS),importance sampling(IS),line sampling(LS)and subset simulation(SS)are derived and analyzed.The proposed contribution indexes of sample can provide valuable information understanding the methods deeply,and enlighten potential improvement of methods.It is found that the main differences between these investigated methods lie in the contribution indexes of the safety samples,which are the main factors to the efficiency of the methods.Moreover,numerical examples are used to validate these findings.展开更多
This paper presents component importance analysis for virtualized system with live migration. The component importance analysis is significant to determine the system design of virtualized system from availability and...This paper presents component importance analysis for virtualized system with live migration. The component importance analysis is significant to determine the system design of virtualized system from availability and cost points of view. This paper discusses the importance of components with respect to system availability. Specifically, we introduce two different component importance analyses for hybrid model (fault trees and continuous-time Markov chains) and continuous-time Markov chains, and show the analysis for existing probabilistic models for virtualized system. In numerical examples, we illustrate the quantitative component importance analysis for virtualized system with live migration.展开更多
During the life of an offshore structure, its structural strength declines due to various kinds of damages related to the time factor. In this paper, four major kinds of damages, including damages caused by fatigue, d...During the life of an offshore structure, its structural strength declines due to various kinds of damages related to the time factor. In this paper, four major kinds of damages, including damages caused by fatigue, dent, corrosion and marine life, are discussed. Based on these analyses, formulas for the evaluation of the damaged structure reliability are derived. Furthermore the computer program ISM for the analysis of structural reliability is developed by the use of Advanced First Order Second Moment method and Monte-Carlo Importance Sampling method. The reliability of a turbular joint and a beam are studied as numerical examples. The results show that the theory and the analysis method given in this paper are reasonable and effective.展开更多
Corn to sugar process has long faced the risks of high energy consumption and thin profits.However,it’s hard to upgrade or optimize the process based on mechanism unit operation models due to the high complexity of t...Corn to sugar process has long faced the risks of high energy consumption and thin profits.However,it’s hard to upgrade or optimize the process based on mechanism unit operation models due to the high complexity of the related processes.Big data technology provides a promising solution as its ability to turn huge amounts of data into insights for operational decisions.In this paper,a neural network-based production process modeling and variable importance analysis approach is proposed for corn to sugar processes,which contains data preprocessing,dimensionality reduction,multilayer perceptron/convolutional neural network/recurrent neural network based modeling and extended weights connection method.In the established model,dextrose equivalent value is selected as the output,and 654 sites from the DCS system are selected as the inputs.LASSO analysis is first applied to reduce the data dimension to 155,then the inputs are dimensionalized to 50 by means of genetic algorithm optimization.Ultimately,variable importance analysis is carried out by the extended weight connection method,and 20 of the most important sites are selected for each neural network.The results indicate that the multilayer perceptron and recurrent neural network models have a relative error of less than 0.1%,which have a better prediction result than other models,and the 20 most important sites selected have better explicable performance.The major contributions derived from this work are of significant aid in process simulation model with high accuracy and process optimization based on the selected most important sites to maintain high quality and stable production for corn to sugar processes.展开更多
While public spaces of tourist villages(PSTVs)have increasingly gained more policy and development attention,their empirical investigations are still limited.This study aims to develop a quantitative methodological ap...While public spaces of tourist villages(PSTVs)have increasingly gained more policy and development attention,their empirical investigations are still limited.This study aims to develop a quantitative methodological approach of assessing PSTVs through the use of Analytic Hierarchy Process(AHP)to measure tourists’satisfaction.This approach involves experts’and tourists’judgment processes,and the resultant assessment matrix is applied to suggest the strengths and weaknesses of the PSTVs using an Importance-Performance Analysis(IPA).The results from Jiaochangwei Village in Shenzhen suggest that"street spaces,""square spaces,""coastal spaces,""green spaces,""traffic facilities,""public service facilities,""culture,"and"management and maintenance"are key factors to evaluate the use and quality of PSTVs.This paper offers insights into the theoretical investigation and practical development of PSTVs for tourism and village planning decision makers.展开更多
This paper contributes to the structural reliability problem by presenting a novel approach that enables for identification of stochastic oscillatory processes as a critical input for given mechanical models. Identifi...This paper contributes to the structural reliability problem by presenting a novel approach that enables for identification of stochastic oscillatory processes as a critical input for given mechanical models. Identification development follows a transparent image processing paradigm completely independent of state-of-the-art structural dynamics, aiming at delivering a simple and wide purpose method. Validation of the proposed importance sampling strategy is based on multi-scale clusters of realizations of digitally generated non-stationary stochastic processes. Good agreement with the reference pure Monte Carlo results indicates a significant potential in reducing the computational task of first passage probabilities estimation, an important feature in the field of e.g., probabilistic seismic design or risk assessment generally.展开更多
Background: Measles is a highly contagious infection caused by the measles virus with a worldwide distribution. Measles is one of the diseases that have been reported in our country since 1945. It is known that intern...Background: Measles is a highly contagious infection caused by the measles virus with a worldwide distribution. Measles is one of the diseases that have been reported in our country since 1945. It is known that international travelers are an important source of infectious pathologies. Our goal is to document a case of imported Measles and the difficulty of diagnosing it, especially in non-epidemic times. Cases Presentation: We presently report a 20-year-old woman who was hospitalized at the Infectious Disease Service for fever and maculopapular rash. She had traveled outside of Albania. Measles ELISA IgM (blood) resulted positive while other serological examinations resulted negative. Our case was treated with antibiotics, multivitamins and intravenous fluids. She was subsequently discharged home in good clinical condition. Conclusions: Measles should be included in the differential diagnosis of patients with symptoms of fever and rash, in particular when they have traveled abroad. Patients who have received the Measles vaccine should not be excluded from clinical suspicion and further diagnostic tests for this disease as it can affect this group of patients as well.展开更多
基金Jiangxi Province Double Thousand Talent-Leader of Natural Science Project(jxsq2023101038)Jiangxi Province Urgently Overseas Talent Project(2022BCJ25027)+1 种基金The Key Research Projects in Jiangxi Province(20223BBH8007&20232BBG70014)Innovation Team Project in Key Areas of Jiujiang City Base and Talent Plan(S2022TDJS029).
文摘Background:Agarwood,primarily derived from the Aquilaria and Gyrinops genera,holds significant economic importance.However,there is a lack of comprehensive investigations providing guidance to importing nations regarding cultivation quantities and expected yields of Agarwood from distinct species.This study aims to address this gap by exploring the historical context and trade evolution of Agarwood,highlighting its global importance,and the challenges associated with securing accurate species information.Method:On-site visits to Agarwood cultivation sites were conducted to gain a nuanced understanding of Aquilaria species and their cultivation requirements.Additionally,a thorough analysis of global export and import data for Agarwood products over the last decade was undertaken.Results:China Mainland emerged as the leading exporter of Agarwood,averaging an annual export value of USD 1 million.India’s substantial exports challenge the prevailing notion of limited Agarwood production within its borders.Hong Kong and Singapore are pivotal distribution hubs,while Hong Kong and Taipei feature prominently as import destinations.Our analysis uncovers anomalies in the representation of Agarwood producers from 2001 to 2008,suggesting potential misclassification of Aquilaria Agarwood as Gyrinops in global export information.These findings underscore the urgency of investigating classification and reporting practices in the Agarwood trade.Furthermore,A.filaria emerges as a notable source,while A.malaccensis is decline in prominence.Conclusion:This study provides crucial insights for policymakers,stakeholders,and industry players seeking to make informed decisions in the Agarwood trade landscape.The results highlight the need for accurate species identification,classification,and reporting practices to ensure sustainable cultivation and trade of Agarwood.
基金supported by the National Natural Science Foundation of China(71571004)
文摘In a system of systems(SoS),resilience is an important factor in maintaining the functionality,stability,and enhancing the operation effectiveness.From the perspective of resilience,this paper studies the importance of the SoS,and a resilience-based importance measure analysis is conducted to provide suggestions in the design and optimization of the structure of the SoS.In this paper,the components of the SoS are simplified as four kinds of network nodes:sensor,decision point,influencer,and target.In this networked SoS,the number of operation loops is used as the performance indicator,and an approximate algorithm,which is based on eigenvalue of the adjacency matrix,is proposed to calculate the number of operation loops.In order to understand the performance change of the SoS during the attack and defense process in the operations,an integral resilience model is proposed to depict the resilience of the SoS.From different perspectives of enhancing the resilience,different measures,parameters and the corresponding algorithms for the resilience importance of components are proposed.Finally,a case study on an SoS is conducted to verify the validity of the network modelling and the resiliencebased importance analysis method.
文摘The importance analysis method represents a powerful tool for quantifying the impact of input uncertainty on the output uncertainty.When an input variable is described by a specific interval rather than a certain probability distribution,the interval importance measure of input interval variable can be calculated by the traditional non-probabilistic importance analysis methods.Generally,the non-probabilistic importance analysis methods involve the Monte Carlo simulation(MCS)and the optimization-based methods,which both have high computational cost.In order to overcome this problem,this study proposes an interval important analytical method avoids the time-consuming optimization process.First,the original performance function is decomposed into a combination of a series of one-dimensional subsystems.Next,the interval of each variable is divided into several subintervals,and the response value of each one-dimensional subsystem at a specific input point is calculated.Then,the obtained responses are taken as specific values of the new input variable,and the interval importance is calculated by the approximated performance function.Compared with the traditional non-probabilistic importance analysis method,the proposed method significantly reduces the computational cost caused by the MCS and optimization process.In the proposed method,the number of function evaluations is equal to one plus the sum of the subintervals of all of the variables.The efficiency and accuracy of the proposed method are verified by five examples.The results show that the proposed method is not only efficient but also accurate.
基金National Natural Science Foundation of China(No.61164009)the Science and Technology Research Project,Department of Education of Jiangxi Province,China(No.GJJ14420)Natural Science Foundation of Jiangxi Province,China(No.20132BAB206026)
文摘Importance analysis quantifies the critical degree of individual component. Compared with the traditional binary state system,importance analysis of the multi-state system is more aligned with the practice. Because the multi-valued decision diagram( MDD) can reflect the relationship between the components and the system state bilaterally, it was introduced into the reliability calculation of the multi-state system( MSS). The building method,simplified criteria,and path search and probability algorithm of MSS structure function MDD were given,and the reliability of the system was calculated. The computing methods of importance based on MDD and direct partial logic derivatives( DPLD) were presented. The diesel engine fuel supply system was taken as an example to illustrate the proposed method. The results show that not only the probability of the system in each state can be easily obtained,but also the influence degree of each component and its state on the system reliability can be obtained,which is conducive to the condition monitoring and structure optimization of the system.
文摘For the best dynamic performance of a co-cured composite damping instrument panel with light weight and high strength, a multilayer sandwich structure with polymethaerylimide (PMI) foam combined with embedded and co-cured composite damping structure is proposed. The struetue can maintain the excellent mechanical properties of composite materials, and achieve the damping and light effect at the same time. Input variables which may affect the dynamic performance of the instrument panel were selected and variance based importance measure was analyzed through multi- finite element method (FEM) analysis. Using the results of the importance measure analysis, with other design requirements, the important design variable was optimized and an instrument panel with the best dynamic performance under the requirements of light weight and high strength was obtained. The structure of the instrument panel can provide reference for the design of precision, high speed, and dynamic composite component. The importance measure analysis of dynamic performance of the instrument panel can provide a reference for relative design.
文摘With the trade network analysis method and bilateral country-product level trade data of 2017-2020,this paper reveals the overall characteristics and intrinsic vulnerabilities of China’s global supply chains.Our research finds that first,most global supply-chain-vulnerable products are from technology-intensive sectors.For advanced economies,their supply chain vulnerabilities are primarily exposed to political and economic alliances.In comparison,developing economies are more dependent on regional communities.Second,China has a significant export advantage with over 80%of highly vulnerable intermediate inputs relying on imports of high-end electrical,mechanical and chemical products from advanced economies or their multinational companies.China also relies on developing economies for the import of some resource products.Third,during the trade frictions from 2018 to 2019 and the subsequent COVID-19 pandemic,there was a significant reduction in the supply chain vulnerabilities of China and the US for critical products compared with other products,which reflects a shift in the layout of critical product supply chains to ensure not just efficiency but security.China should address supply chain vulnerabilities by bolstering supply-side weaknesses,diversifying import sources,and promoting international coordination and cooperation.
文摘National logistics system in Indonesia can be categorized as inefficient logistics system due to current number of non-value added (NVA) activities. The unreliable National logistics system and the complexity of distribution system are the big obstacles. This study aims to analyze the value and to propose recommendation for further improvement of National distribution system for imported product. This study employed convenience sampling through in-depth interview to analyze the activity in freight forwarder (FF), distributor and retailer. To demonstrate and analyze the activity process in each party, Process Activity Mapping (PAM) was used as a tool. The study results showed that the delivery speed in Jakarta (8.4 min/km) is slower than that of Surabaya (6.6 min/km). The government support through creating adequate infrastructure, good bureaucracy system and good collaboration directly affects the activities of FF, distributor and retailer. Improving FF performance in a timely and reliable manner is required to reduce errors that may occur. Moreover, encouraging the practice of cold chain management is also necessary in distributing the product throughout Indonesia. The pull strategy can be chosen by retailer to eliminate storage activity. Meanwhile, the use of information technology (IT) system is essential to encourage better inventory management, database management and sharing information in distributor and retailer stage.
文摘4. Increasing import of rare earth resources products As a big producer and an important export country of rare earth products for years, rare earths import is in an auxiliary position in China. Import volume is rather small. However, since the strengthened macro control measures
文摘Problems existed in the import & export of Chinese rare earths in 2006 Although it was holistically stable on the export of Chinese rare earth products, there were some problems that are reflected in the following aspects:
基金Supported by Project of Changzhou Science and Technology Bureau(CJ20130036)~~
文摘The situation of intercepted weeds from wooI in Jiangsu port during 2004 to 2012 was introduced in this paper, and the corresponding countermeasures were then proposed. The resuIts showed that a total of 38 famiIies, 138 genera, 268 species and 13 868 species-times of weeds were intercepted, incIuding 3 famiIies, 11 genera, 20 species and 2 094 species-times of quarantine weeds. The weeds were intercepted from the wooI introduced from 19 countries and regions, among which, Australia had the highest species-times, accounting for 71.0% of the total. Bases on the analysis of interception situation of weeds, some countermeasures were pro-posed from the perspectives of risk assessment, quarantine supervision, quarantine treatment and epidemic surveiI ance, providing some reference for estabIishing a perfect system for preventing the invasion of exotic weeds.
基金NSAF(Grant No.U1530122)the Aeronautical Science Foundation of China(Grant No.ASFC-20170968002)the Fundamental Research Funds for the Central Universities of China(XMU,20720180072).
文摘In structural reliability analysis,simulation methods are widely used.The statistical characteristics of failure probability estimate of these methods have been well investigated.In this study,the sensitivities of the failure probability estimate and its statistical characteristics with regard to sample,called‘contribution indexes’,are proposed to measure the contribution of sample.The contribution indexes in four widely simulation methods,i.e.,Monte Carlo simulation(MCS),importance sampling(IS),line sampling(LS)and subset simulation(SS)are derived and analyzed.The proposed contribution indexes of sample can provide valuable information understanding the methods deeply,and enlighten potential improvement of methods.It is found that the main differences between these investigated methods lie in the contribution indexes of the safety samples,which are the main factors to the efficiency of the methods.Moreover,numerical examples are used to validate these findings.
文摘This paper presents component importance analysis for virtualized system with live migration. The component importance analysis is significant to determine the system design of virtualized system from availability and cost points of view. This paper discusses the importance of components with respect to system availability. Specifically, we introduce two different component importance analyses for hybrid model (fault trees and continuous-time Markov chains) and continuous-time Markov chains, and show the analysis for existing probabilistic models for virtualized system. In numerical examples, we illustrate the quantitative component importance analysis for virtualized system with live migration.
文摘During the life of an offshore structure, its structural strength declines due to various kinds of damages related to the time factor. In this paper, four major kinds of damages, including damages caused by fatigue, dent, corrosion and marine life, are discussed. Based on these analyses, formulas for the evaluation of the damaged structure reliability are derived. Furthermore the computer program ISM for the analysis of structural reliability is developed by the use of Advanced First Order Second Moment method and Monte-Carlo Importance Sampling method. The reliability of a turbular joint and a beam are studied as numerical examples. The results show that the theory and the analysis method given in this paper are reasonable and effective.
基金supports of Special Foundation for State Major Basic Research Program of China(Grant No.2021YFD2101000).
文摘Corn to sugar process has long faced the risks of high energy consumption and thin profits.However,it’s hard to upgrade or optimize the process based on mechanism unit operation models due to the high complexity of the related processes.Big data technology provides a promising solution as its ability to turn huge amounts of data into insights for operational decisions.In this paper,a neural network-based production process modeling and variable importance analysis approach is proposed for corn to sugar processes,which contains data preprocessing,dimensionality reduction,multilayer perceptron/convolutional neural network/recurrent neural network based modeling and extended weights connection method.In the established model,dextrose equivalent value is selected as the output,and 654 sites from the DCS system are selected as the inputs.LASSO analysis is first applied to reduce the data dimension to 155,then the inputs are dimensionalized to 50 by means of genetic algorithm optimization.Ultimately,variable importance analysis is carried out by the extended weight connection method,and 20 of the most important sites are selected for each neural network.The results indicate that the multilayer perceptron and recurrent neural network models have a relative error of less than 0.1%,which have a better prediction result than other models,and the 20 most important sites selected have better explicable performance.The major contributions derived from this work are of significant aid in process simulation model with high accuracy and process optimization based on the selected most important sites to maintain high quality and stable production for corn to sugar processes.
基金funded by the Humanities and Social Science Foundation of the Ministry of Education of China(17YJAZH059)the Natural Science Foundation of Guangdong Province,China(2018A0303130032).
文摘While public spaces of tourist villages(PSTVs)have increasingly gained more policy and development attention,their empirical investigations are still limited.This study aims to develop a quantitative methodological approach of assessing PSTVs through the use of Analytic Hierarchy Process(AHP)to measure tourists’satisfaction.This approach involves experts’and tourists’judgment processes,and the resultant assessment matrix is applied to suggest the strengths and weaknesses of the PSTVs using an Importance-Performance Analysis(IPA).The results from Jiaochangwei Village in Shenzhen suggest that"street spaces,""square spaces,""coastal spaces,""green spaces,""traffic facilities,""public service facilities,""culture,"and"management and maintenance"are key factors to evaluate the use and quality of PSTVs.This paper offers insights into the theoretical investigation and practical development of PSTVs for tourism and village planning decision makers.
文摘This paper contributes to the structural reliability problem by presenting a novel approach that enables for identification of stochastic oscillatory processes as a critical input for given mechanical models. Identification development follows a transparent image processing paradigm completely independent of state-of-the-art structural dynamics, aiming at delivering a simple and wide purpose method. Validation of the proposed importance sampling strategy is based on multi-scale clusters of realizations of digitally generated non-stationary stochastic processes. Good agreement with the reference pure Monte Carlo results indicates a significant potential in reducing the computational task of first passage probabilities estimation, an important feature in the field of e.g., probabilistic seismic design or risk assessment generally.
文摘Background: Measles is a highly contagious infection caused by the measles virus with a worldwide distribution. Measles is one of the diseases that have been reported in our country since 1945. It is known that international travelers are an important source of infectious pathologies. Our goal is to document a case of imported Measles and the difficulty of diagnosing it, especially in non-epidemic times. Cases Presentation: We presently report a 20-year-old woman who was hospitalized at the Infectious Disease Service for fever and maculopapular rash. She had traveled outside of Albania. Measles ELISA IgM (blood) resulted positive while other serological examinations resulted negative. Our case was treated with antibiotics, multivitamins and intravenous fluids. She was subsequently discharged home in good clinical condition. Conclusions: Measles should be included in the differential diagnosis of patients with symptoms of fever and rash, in particular when they have traveled abroad. Patients who have received the Measles vaccine should not be excluded from clinical suspicion and further diagnostic tests for this disease as it can affect this group of patients as well.