Recent research demonstrates the need for comprehensive frameworks to achieve an appropriate level of resilience(e.g.,energy,seismic)of the European building stock,through integrated retrofitting interventions.Differe...Recent research demonstrates the need for comprehensive frameworks to achieve an appropriate level of resilience(e.g.,energy,seismic)of the European building stock,through integrated retrofitting interventions.Different frameworks have been proposed to identify optimal interventions when several feasible alternatives are available,considering multiple decision variables of different nature,such as social,economic,or technical.Within these efforts and frameworks,less attention has been paid to the post-earthquake recovery time of buildings and communities,thus ignoring the significance of reaching a desired recovery state(e.g.,functional recovery)within a specified time frame.To overcome this limitation,this study estimates post-earthquake recovery times and uses them as one of the decision variables in multi-criteria identification of optimal retrofitting of an existing RC building.The case-study building is representative of the Italian school buildings constructed between the 1960s and 1970s and was analysed under two seismic hazard levels(moderate and high).Following the identification of the main structural deficiencies of the as-built structure through nonlinear static analyses,four seismic retrofit measures were selected.Then,the earthquake-induced downtime of each of the four retrofitted building configurations was assessed,analysing the different recovery times as a function of the seismic hazard level and the recovery state.A downtime-based metric,namely the expected annual downtime,was introduced as decision variable within an available multi-criteria decision-making framework to include the impact of downtime,rank the four retrofit measures and identify the preferable one.展开更多
The models for calculating the heat transfer in converters allow the accurate control of heat dissipation caused by downtime,and thus help in crease scrap ratio and reduce energy consumptio n.ANSYS 17 was used to esta...The models for calculating the heat transfer in converters allow the accurate control of heat dissipation caused by downtime,and thus help in crease scrap ratio and reduce energy consumptio n.ANSYS 17 was used to establish such a model to analyse the coupling law between the downtime and heat dissipation of the converter and the temperature drop of molten iron.Temperature was measured by infrared detection,and model accuracy was verified by comparative analysis.The variation law of the amount of cold charge added for different downtimes under different process conditions was studied.The results show that the range of the variation of heat dissipation caused by downtime is 8.9-78.5 GJ.If the downtime increases by 30 min,heat dissipation of dephosphorisation(deP)and decarburisation(deC)converters increases by about 23.4 and 41.3 GJ,respectively.In a certain smelting cycle,the temperature drop of the molten iron for deP,deC and conventional converters increases by about 12.5,15.0 and 17.0 K,respectively;and the amount of scrap added in the double-linking and conventional smelting processes decreases by 0.93 and 0.75%,respectively.展开更多
The paper discusses the importance of recording and analyzing downtime in processing enterprises, and takes Shanghai Mila Brew Company Limited as the example to analyze the problems in recording and analyzing downtime...The paper discusses the importance of recording and analyzing downtime in processing enterprises, and takes Shanghai Mila Brew Company Limited as the example to analyze the problems in recording and analyzing downtime. Finally, suggestions of improvement are given out.展开更多
How to reduce downtime and improve availability of the complex equipment is very important. Although the unscheduled downtime（USDT） issues of the equipment are very complex, the self-organized criticality（SOC） is ...How to reduce downtime and improve availability of the complex equipment is very important. Although the unscheduled downtime（USDT） issues of the equipment are very complex, the self-organized criticality（SOC） is the right theory to study complex systems evolution and opens up a new window to the investigation of disasters, such as the sudden failure of the equipment. Firstly,SOC theory and its validation method are introduced. Then an SOC validation method for USDT of the equipment is proposed based on the above theory. Case study is done on bottleneck equipment in a factory and corresponding data pre-process work is done. The rescaled-range（R/S） analysis method is used to calculate the Hurst exponent of USDT time-series data in order to determine the long-range correlation of USDT data on time scale;at the same time the spatial power-law characteristic of USDT time series data is studied. The result shows that the characteristics of SOC are revealed in USDT data of the equipment according to the criterion of SOC. In addition, based on the characteristics of SOC,the overall framework of the prediction method for major sudden failure of the equipment is proposed based on SOC.展开更多
Downtime due to adverse wave conditions for vessels at berth is an important commercial aspect in the planning and development of a sea port or a berthing terminal. This paper describes a practical technique for preli...Downtime due to adverse wave conditions for vessels at berth is an important commercial aspect in the planning and development of a sea port or a berthing terminal. This paper describes a practical technique for preliminary assessment of operational downtime at a proposed bulk terminal. Time-series wind and wave data at an offshore location was purchased. Numerical modelling was then carried out using the MIKE21 SW （spectral wave） model developed by DHI （Deutsches Hydrographisches Institut） to transform these offshore waves into inshore in order to derive wave conditions at the berth. Both wind-waves and swell-waves were considered. Waves affecting the head and beam of a vessel were considered separately for a wide range of vessel sizes with DT （displacement tonnage） ranging from 5,000 tons to 〉 200,000 tons. The limiting wave height H5% was used. Operational downtime was also calculated using significant wave height, Hs as a criterion with limits ofHs = 1.0 m for beam seas and Hs = 1.5 m for head seas. The methodology and lessons learnt from the study can be applied for the development of any sea port worldwide.展开更多
Earthquake is one of the natural disasters that affects the buildings and communities in developing countries.It causes different levels of damages to the buildings,making them uninhabitable for a period of time,calle...Earthquake is one of the natural disasters that affects the buildings and communities in developing countries.It causes different levels of damages to the buildings,making them uninhabitable for a period of time,called downtime(DT).This paper proposes a Fuzzy Logic hierarchical method to estimate the downtime of residential buildings in developing countries after an earthquake.The use of expert-based systems allows quantifying the indicators involved in the model using descriptive knowledge instead of hard data,accounting also for the un-certainties that may affect the analysis.The applicability of the methodology is illustrated using the information gathered after the 2015 Gorkha,Nepal,earthquake as a case study.On April 25,2015,Nepal was hit by the Mw 7.8 Gorkha earthquake,which damaged and destroyed more than 500.000 residential buildings.Information obtained from a Rapid Visual Damage Assessment(RVDA)is used through a hierarchical scheme to evaluate the building damageability.Sensitivity analysis based on Sobol method is implemented to evaluate the impor-tance of parameters gathered in the RVDA for building damage estimation.The findings of this work may be used to estimate the restoration time of damaged buildings in developing countries and to plan preventive safety measures.展开更多
Severe wind-wave due to tropical cyclone Linda can cause port downtime which affects port operations such as berthing, mooting and （un）loading of the ship. The ship motions are criteria for limiting the port operati...Severe wind-wave due to tropical cyclone Linda can cause port downtime which affects port operations such as berthing, mooting and （un）loading of the ship. The ship motions are criteria for limiting the port operations, human safety and preventing the damage of port equipment and furniture. Therefore, this study discusses moored ship motions due to severe wind-wave during the tropical cyclone Linda which entered the Gulf of Thailand in November 1997. The ship motions are represented in the moored ship analysis at SRH （Sriracha Harbour Port） and BLCP （BLCP Coal-Fired Power Plant Port）, and are subject to the static environmental load on the ship in accordance with Spanish Standard （ROM 0.2-1990） [1]. The environment in numerical model is derived from the wave model and hydrodynamics model using the application of Delft3D-WAVE and Delft3D-FLOW. The model location includes Ao Udom Bay and Rayong Sea. The model results represent the environment at Rayong Sea which is more severe than Ao Udom Bay. The ship motions at BLCP are mostly larger than SRH.展开更多
Cloud systems, which are typical cyber–physical systems, consist of physical nodes and virtualized facilities that collaborate to fulfill cloud computing services. The advent of virtualization technology engenders re...Cloud systems, which are typical cyber–physical systems, consist of physical nodes and virtualized facilities that collaborate to fulfill cloud computing services. The advent of virtualization technology engenders resource sharing and service parallelism in cloud services, introducing novel challenges to system modeling. In this study, we construct a systematic model that concurrently evaluates system reliability, performance, and power consumption (PC) while delineating cloud service disruptions arising from random hardware and software failures. Initially, we depict system states using a birth–death process that accommodates resource sharing and service parallelism. Given the relatively concise service duration and regular failure distributions, we employ transient-state transition probabilities instead of steady-state analysis. The birth–death process effectively links system reliability, performance, and PC through service durations governed by service assignment decisions and failure/repair distributions. Subsequently, we devise a multistage sample path randomization method to estimate system metrics and other factors related to service availability. The findings highlight that the trade-off between performance and PC, under the umbrella of reliability guarantees, hinges on the equilibrium between service duration and unit power. To further delve into the subject, we formulate optimization models for service assignment and juxtapose optimal decisions under varying availability scenarios, workload levels, and service attributes. Numerical results indicate that service parallelism can improve performance and conserve energy when the workload remains moderate. However, as the workload escalates, the repercussions of resource sharing-induced performance loss become more pronounced due to resource capacity limitations. In cases where system availability is constrained, resource sharing should be approached cautiously to ensure adherence to deadline requirements. This study theoretically analyzes the interrelations among system reliability, performance, and PC, offering valuable insights for making informed decisions in cloud service assignments.展开更多
On the basis of Ref.\, the M x/G(M/G)/1 repairable queueing system with single delay vacation is discussed again. The following reliability problems of the service station are studied: (a) The probability that it fai...On the basis of Ref.\, the M x/G(M/G)/1 repairable queueing system with single delay vacation is discussed again. The following reliability problems of the service station are studied: (a) The probability that it fails at time t , i.e. its unavailability; (b) The expected failure number during the time interval (0,t\];; (c) The expected failure number during the ″server busy period″; (d) The expected downtime during the time interval (0,t\]. Some reliability results of the service station are obtained. These results would be interest to reliability analysts.展开更多
Disruptions in the manufacturing process cast substantial impacts on the consumer’s centric values,cost,and overall efficiency.The ripple effect of these disruptions is observed in the whole assembly line.The proper ...Disruptions in the manufacturing process cast substantial impacts on the consumer’s centric values,cost,and overall efficiency.The ripple effect of these disruptions is observed in the whole assembly line.The proper analysis and mitigation of disruptions is the key to the proficiency of the plant and resource utilisation.The research focuses on the quantitative analysis of the impact of disruptions of the manufacturing process,which is performed by analysing the disruptive workstation dynamically.The disruptive workstations have a significant impact on succeeding and preceding workstations,which have been analysed dynamically,and accordingly,the preset alarm trip points are elevated.The results show that lowering the number of starts and stops decreases the number of rejections of valuable process batches that finally improve efficiency.Finally,the developed model is implemented on a polycrystalline diamond compact drill bit manufacturing plant.The results are compared with the research work of other researchers,showing a 60%reduction in the number of start/stop events,60%reduction in downtime,while a 75%reduction in the number of rejections is noted.展开更多
基金funded by the Italian Civil Protection Department and“PriorBuilt-Prioritisation of the Italian regions for seismic and energy performance upgrading of the existing buildings”funded by ReLUIS.Additionally,it was developed as part of the activities of CONSTRUCT–Instituto de I&D em Estruturas e Construções(UID/04708),CERIS(UIDB/04625)+1 种基金the project SERENE(2022.08138.PTDC)all funded by Fundação para a Ciência e a Tecnologia,I.P./MCTES(PIDDAC).
文摘Recent research demonstrates the need for comprehensive frameworks to achieve an appropriate level of resilience(e.g.,energy,seismic)of the European building stock,through integrated retrofitting interventions.Different frameworks have been proposed to identify optimal interventions when several feasible alternatives are available,considering multiple decision variables of different nature,such as social,economic,or technical.Within these efforts and frameworks,less attention has been paid to the post-earthquake recovery time of buildings and communities,thus ignoring the significance of reaching a desired recovery state(e.g.,functional recovery)within a specified time frame.To overcome this limitation,this study estimates post-earthquake recovery times and uses them as one of the decision variables in multi-criteria identification of optimal retrofitting of an existing RC building.The case-study building is representative of the Italian school buildings constructed between the 1960s and 1970s and was analysed under two seismic hazard levels(moderate and high).Following the identification of the main structural deficiencies of the as-built structure through nonlinear static analyses,four seismic retrofit measures were selected.Then,the earthquake-induced downtime of each of the four retrofitted building configurations was assessed,analysing the different recovery times as a function of the seismic hazard level and the recovery state.A downtime-based metric,namely the expected annual downtime,was introduced as decision variable within an available multi-criteria decision-making framework to include the impact of downtime,rank the four retrofit measures and identify the preferable one.
基金National Natural Science Foundation of China(Grant Nos.51674030 and 51574032)National Key Research and Development Program of China(Grant No.2016YFB0601301).
文摘The models for calculating the heat transfer in converters allow the accurate control of heat dissipation caused by downtime,and thus help in crease scrap ratio and reduce energy consumptio n.ANSYS 17 was used to establish such a model to analyse the coupling law between the downtime and heat dissipation of the converter and the temperature drop of molten iron.Temperature was measured by infrared detection,and model accuracy was verified by comparative analysis.The variation law of the amount of cold charge added for different downtimes under different process conditions was studied.The results show that the range of the variation of heat dissipation caused by downtime is 8.9-78.5 GJ.If the downtime increases by 30 min,heat dissipation of dephosphorisation(deP)and decarburisation(deC)converters increases by about 23.4 and 41.3 GJ,respectively.In a certain smelting cycle,the temperature drop of the molten iron for deP,deC and conventional converters increases by about 12.5,15.0 and 17.0 K,respectively;and the amount of scrap added in the double-linking and conventional smelting processes decreases by 0.93 and 0.75%,respectively.
文摘The paper discusses the importance of recording and analyzing downtime in processing enterprises, and takes Shanghai Mila Brew Company Limited as the example to analyze the problems in recording and analyzing downtime. Finally, suggestions of improvement are given out.
基金supported by the National Natural Science Foundation of China(51075060)
文摘How to reduce downtime and improve availability of the complex equipment is very important. Although the unscheduled downtime（USDT） issues of the equipment are very complex, the self-organized criticality（SOC） is the right theory to study complex systems evolution and opens up a new window to the investigation of disasters, such as the sudden failure of the equipment. Firstly,SOC theory and its validation method are introduced. Then an SOC validation method for USDT of the equipment is proposed based on the above theory. Case study is done on bottleneck equipment in a factory and corresponding data pre-process work is done. The rescaled-range（R/S） analysis method is used to calculate the Hurst exponent of USDT time-series data in order to determine the long-range correlation of USDT data on time scale;at the same time the spatial power-law characteristic of USDT time series data is studied. The result shows that the characteristics of SOC are revealed in USDT data of the equipment according to the criterion of SOC. In addition, based on the characteristics of SOC,the overall framework of the prediction method for major sudden failure of the equipment is proposed based on SOC.
文摘Downtime due to adverse wave conditions for vessels at berth is an important commercial aspect in the planning and development of a sea port or a berthing terminal. This paper describes a practical technique for preliminary assessment of operational downtime at a proposed bulk terminal. Time-series wind and wave data at an offshore location was purchased. Numerical modelling was then carried out using the MIKE21 SW （spectral wave） model developed by DHI （Deutsches Hydrographisches Institut） to transform these offshore waves into inshore in order to derive wave conditions at the berth. Both wind-waves and swell-waves were considered. Waves affecting the head and beam of a vessel were considered separately for a wide range of vessel sizes with DT （displacement tonnage） ranging from 5,000 tons to 〉 200,000 tons. The limiting wave height H5% was used. Operational downtime was also calculated using significant wave height, Hs as a criterion with limits ofHs = 1.0 m for beam seas and Hs = 1.5 m for head seas. The methodology and lessons learnt from the study can be applied for the development of any sea port worldwide.
基金This study was carried out within the RETURN Extended Partnership and received funding from the European Union Next-GenerationEU(Na-tional Recovery and Resilience Plan-NRRP,Mission 4,Component 2,Investment 1.3-D.D.12432/8/2022,PE0000005).
文摘Earthquake is one of the natural disasters that affects the buildings and communities in developing countries.It causes different levels of damages to the buildings,making them uninhabitable for a period of time,called downtime(DT).This paper proposes a Fuzzy Logic hierarchical method to estimate the downtime of residential buildings in developing countries after an earthquake.The use of expert-based systems allows quantifying the indicators involved in the model using descriptive knowledge instead of hard data,accounting also for the un-certainties that may affect the analysis.The applicability of the methodology is illustrated using the information gathered after the 2015 Gorkha,Nepal,earthquake as a case study.On April 25,2015,Nepal was hit by the Mw 7.8 Gorkha earthquake,which damaged and destroyed more than 500.000 residential buildings.Information obtained from a Rapid Visual Damage Assessment(RVDA)is used through a hierarchical scheme to evaluate the building damageability.Sensitivity analysis based on Sobol method is implemented to evaluate the impor-tance of parameters gathered in the RVDA for building damage estimation.The findings of this work may be used to estimate the restoration time of damaged buildings in developing countries and to plan preventive safety measures.
文摘Severe wind-wave due to tropical cyclone Linda can cause port downtime which affects port operations such as berthing, mooting and （un）loading of the ship. The ship motions are criteria for limiting the port operations, human safety and preventing the damage of port equipment and furniture. Therefore, this study discusses moored ship motions due to severe wind-wave during the tropical cyclone Linda which entered the Gulf of Thailand in November 1997. The ship motions are represented in the moored ship analysis at SRH （Sriracha Harbour Port） and BLCP （BLCP Coal-Fired Power Plant Port）, and are subject to the static environmental load on the ship in accordance with Spanish Standard （ROM 0.2-1990） [1]. The environment in numerical model is derived from the wave model and hydrodynamics model using the application of Delft3D-WAVE and Delft3D-FLOW. The model location includes Ao Udom Bay and Rayong Sea. The model results represent the environment at Rayong Sea which is more severe than Ao Udom Bay. The ship motions at BLCP are mostly larger than SRH.
基金supported by the National Natural Science Foundation of China(Grant Nos.72372131,T2293774,and 71901169)the Shaanxi Province Innovative Talents Promotion Plan-Youth Science and Technology Nova Project(Grant No.2022KJXX-50)the Youth Talent Promotion Project of China Association for Science and Technology(Grant No.YESS20200072).
文摘Cloud systems, which are typical cyber–physical systems, consist of physical nodes and virtualized facilities that collaborate to fulfill cloud computing services. The advent of virtualization technology engenders resource sharing and service parallelism in cloud services, introducing novel challenges to system modeling. In this study, we construct a systematic model that concurrently evaluates system reliability, performance, and power consumption (PC) while delineating cloud service disruptions arising from random hardware and software failures. Initially, we depict system states using a birth–death process that accommodates resource sharing and service parallelism. Given the relatively concise service duration and regular failure distributions, we employ transient-state transition probabilities instead of steady-state analysis. The birth–death process effectively links system reliability, performance, and PC through service durations governed by service assignment decisions and failure/repair distributions. Subsequently, we devise a multistage sample path randomization method to estimate system metrics and other factors related to service availability. The findings highlight that the trade-off between performance and PC, under the umbrella of reliability guarantees, hinges on the equilibrium between service duration and unit power. To further delve into the subject, we formulate optimization models for service assignment and juxtapose optimal decisions under varying availability scenarios, workload levels, and service attributes. Numerical results indicate that service parallelism can improve performance and conserve energy when the workload remains moderate. However, as the workload escalates, the repercussions of resource sharing-induced performance loss become more pronounced due to resource capacity limitations. In cases where system availability is constrained, resource sharing should be approached cautiously to ensure adherence to deadline requirements. This study theoretically analyzes the interrelations among system reliability, performance, and PC, offering valuable insights for making informed decisions in cloud service assignments.
基金the Supporing Program of the National Education Ministry for ChineseUniversity Excellent Teachers([2 0 0 0 ]65 )
文摘On the basis of Ref.\, the M x/G(M/G)/1 repairable queueing system with single delay vacation is discussed again. The following reliability problems of the service station are studied: (a) The probability that it fails at time t , i.e. its unavailability; (b) The expected failure number during the time interval (0,t\];; (c) The expected failure number during the ″server busy period″; (d) The expected downtime during the time interval (0,t\]. Some reliability results of the service station are obtained. These results would be interest to reliability analysts.
文摘Disruptions in the manufacturing process cast substantial impacts on the consumer’s centric values,cost,and overall efficiency.The ripple effect of these disruptions is observed in the whole assembly line.The proper analysis and mitigation of disruptions is the key to the proficiency of the plant and resource utilisation.The research focuses on the quantitative analysis of the impact of disruptions of the manufacturing process,which is performed by analysing the disruptive workstation dynamically.The disruptive workstations have a significant impact on succeeding and preceding workstations,which have been analysed dynamically,and accordingly,the preset alarm trip points are elevated.The results show that lowering the number of starts and stops decreases the number of rejections of valuable process batches that finally improve efficiency.Finally,the developed model is implemented on a polycrystalline diamond compact drill bit manufacturing plant.The results are compared with the research work of other researchers,showing a 60%reduction in the number of start/stop events,60%reduction in downtime,while a 75%reduction in the number of rejections is noted.
