Reinforcement corrosion is the main cause of performance deterioration of reinforced concrete(RC)structures.Limited research has been performed to investigate the life-cycle cost(LCC)of coastal bridge piers with nonun...Reinforcement corrosion is the main cause of performance deterioration of reinforced concrete(RC)structures.Limited research has been performed to investigate the life-cycle cost(LCC)of coastal bridge piers with nonuniform corrosion using different materials.In this study,a reliability-based design optimization(RBDO)procedure is improved for the design of coastal bridge piers using six groups of commonly used materials,i.e.,normal performance concrete(NPC)with black steel(BS)rebar,high strength steel(HSS)rebar,epoxy coated(EC)rebar,and stainless steel(SS)rebar(named NPC-BS,NPC-HSS,NPC-EC,and NPC-SS,respectively),NPC with BS with silane soakage on the pier surface(named NPC-Silane),and high-performance concrete(HPC)with BS rebar(named HPC-BS).First,the RBDO procedure is improved for the design optimization of coastal bridge piers,and a bridge is selected to illustrate the procedure.Then,reliability analysis of the pier designed with each group of materials is carried out to obtain the time-dependent reliability in terms of the ultimate and serviceability performances.Next,the repair time of the pier is predicted based on the time-dependent reliability indices.Finally,the time-dependent LCCs for the pier are obtained for the selection of the optimal design.展开更多
The quantitative determination and evaluation of rock brittleness are crucial for the estimation of excavation efficiency and the improvement of hydraulic fracturing efficiency.Therefore,a“three-stage”triaxial loadi...The quantitative determination and evaluation of rock brittleness are crucial for the estimation of excavation efficiency and the improvement of hydraulic fracturing efficiency.Therefore,a“three-stage”triaxial loading and unloading stress path is designed and proposed.Subsequently,six brittleness indices are selected.In addition,the evolution characteristics of the six brittleness indices selected are characterized based on the bedding effect and the effect of confining pressure.Then,the entropy weight method(EWM)is introduced to assign weight to the six brittleness indices,and the comprehensive brittleness index Bcis defined and evaluated.Next,the new brittleness classification standard is determined,and the brittleness differences between the two stress paths are quantified.Finally,compared with the previous evaluation methods,the rationality of the proposed comprehensive brittleness index Bcis also verified.These results indicate that the proposed brittleness index Bccan reflect the brittle characteristics of deep bedded sandstone from the perspective of the whole life-cycle evolution process.Accordingly,the method proposed seems to offer reliable evaluations of the brittleness of deep bedded sandstone in deep engineering practices,although further validation is necessary.展开更多
During the coronavirus disease 2019 (COVID-19) emergency, many hospitals were built or renovated around the world to meet the challenges posed by the rising number of infected cases. Environmental management in the ho...During the coronavirus disease 2019 (COVID-19) emergency, many hospitals were built or renovated around the world to meet the challenges posed by the rising number of infected cases. Environmental management in the hospital life cycle is vital in preventing nosocomial infection and includes many infection control procedures. In certain urgent situations, a hospital must be completed quickly, and work process approval and supervision must therefore be accelerated. Thus, many works cannot be checked in detail. This results in a lack of work liability control and increases the difficulty of ensuring the fulfillment of key infection prevention measures. This study investigates how blockchain technology can transform the work quality inspection workflow to assist in nosocomial infection control under a fast delivery requirement. A blockchain-based life-cycle environmental management framework is proposed to track the fulfillment of crucial infection control measures in the design, construction, and operation stages of hospitals. The proposed framework allows for work quality checking after the work is completed, when some work cannot be checked on time. Illustrative use cases are selected to demonstrate the capabilities of the developed solution. This study provides new insights into applying blockchain technology to address the challenge of environmental management brought by rapid delivery requirements.展开更多
Engineering structures may be exposed to one or more extreme hazards during their life-cycles.Current structural design specifications usually treat multiple hazards separately in designing structures and there is a l...Engineering structures may be exposed to one or more extreme hazards during their life-cycles.Current structural design specifications usually treat multiple hazards separately in designing structures and there is a limited probabilistic basis on extreme load combinations.Additionally,the performance of engineering structures will be deteriorated by the aggressive environments during their service periods,such as chloride attack,concrete carbonation,and wind-induced fatigue.This study presents a probabilistic methodology to assess the time-dependent failure probability of RC bridges with chloride-induced corrosion under the multiple hazards of earthquakes and strong winds.The loss of cross-section area of reinforcements and the reduction in strength of reinforcing steel and concrete cover induced by the chloride attack are considered.Moreover,the Poisson model is employed to obtain the occurrence probabilities of the individual and concurrent earthquake and strong wind events.The convolution integral is used to determine the joint probability distribution of combined load effects under simultaneous earthquakes and strong winds.Numerical results indicate that the structural failure probability under multiple hazards increases significantly during the bridge′s life-cycle due to the chloride corrosion effect.The contribution of each hazard event on the total structural failure probability varies with time.Thus,neglecting the combined influences of multiple hazards and chloride-induced corrosion may bring erroneous predictions in failure probability estimates of RC bridges.展开更多
As the construction sector is a major energy consumer and thus a significant contributor of CO_2 emissions in China,it is important to consider carbon reduction in this industry.This study analyzed six life-cycle stag...As the construction sector is a major energy consumer and thus a significant contributor of CO_2 emissions in China,it is important to consider carbon reduction in this industry.This study analyzed six life-cycle stages and calculated the life-cycle CO_2 emissions of the construction sector in 30 Chinese provincial jurisdictions to understand the disparity among them.Results show that building materials production was the key stage for carbon reduction in the construction sector,followed by the building operation stage.External variables,e.g.,economic growth,industrial structure,urbanization,price fluctuation,and marketization,were significantly correlated with the emission intensity of the construction sector.Specifically,economic growth exhibited an inverted U-shaped relation with CO_2 emissions per capita and per area during the period examined.Secondary industry and land urbanization were negatively correlated with CO_2 emission intensity indicators from the construction sector,whereas tertiary industry and urbanization were positively correlated.Price indices and marketization had negative effects on CO_2 emission intensity.The policy implications of our findings are that cleaner technologies should be encouraged for cement providers,and green purchasing rules for the construction sector should also be established.Pricing tools(e.g.,resource taxes)could help to adjust the demand for raw materials and energy.展开更多
With the continuous development of urban public transportation, the harmful GHG emissions and pollutants generated by itself and the consequent issues such as the losses of residents’ health, economic value and resid...With the continuous development of urban public transportation, the harmful GHG emissions and pollutants generated by itself and the consequent issues such as the losses of residents’ health, economic value and residents’ welfare have become the focus of social attention. In order to study the impacts of promoting new energy vehicles on public transportation pollution mitigation and residents’ health benefits, this paper adopts the LEAP model to build some scenarios that fulfill different development needs to quantitatively analyze the ownership of new energy buses, the reduction of pollutants and the losses of residents’ health welfare. It is concluded that promoting new energy buses comprehensively can significantly reduce the emissions of atmospheric pollutants and the economic losses of residents’ health, but cannot fully realize the targets of greenhouse gas reduction under Life Cycle Analysis.展开更多
The hydrogen fuel cell vehicle is rapidly developing in China for carbon reduction and neutrality.This paper evaluated the life-cycle cost and carbon emission of hydrogen energy via lots of field surveys,including hyd...The hydrogen fuel cell vehicle is rapidly developing in China for carbon reduction and neutrality.This paper evaluated the life-cycle cost and carbon emission of hydrogen energy via lots of field surveys,including hydrogen production and packing in chlor-alkali plants,transport by tube trailers,storage and refueling in hydrogen refueling stations(HRSs),and application for use in two different cities.It also conducted a comparative study for battery electric vehicles(BEVs)and internal combustion engine vehicles(ICEVs).The result indicates that hydrogen fuel cell vehicle(FCV)has the best environmental performance but the highest energy cost.However,a sufficient hydrogen supply can significantly reduce the carbon intensity and FCV energy cost of the current system.The carbon emission for FCV application has the potential to decrease by 73.1%in City A and 43.8%in City B.It only takes 11.0%–20.1%of the BEV emission and 8.2%–9.8%of the ICEV emission.The cost of FCV driving can be reduced by 39.1%in City A.Further improvement can be obtained with an economical and“greener”hydrogen production pathway.展开更多
This research undertook a case study of the life-cycle assessment and techno-economic analysis of the slow pyrolysis of Eucommia stem for the production of wood vinegar and activated carbon.The results showed that the...This research undertook a case study of the life-cycle assessment and techno-economic analysis of the slow pyrolysis of Eucommia stem for the production of wood vinegar and activated carbon.The results showed that the production of one ton of wood vinegar via the slow pyrolysis of Eucommia stem show comparatively low global warming potential(2.37×10^(2) kg CO_(2) eq),primary energy demand(3.16×10^(3) MJ),acidification potential(2.19 kg SO2 eq),antimony depletion potential(3.86×10^(–4) kg antimony eq),and ozone depletion potential(7.46×10^(–6) kg CFC-11 eq)and was more environmentally friendly than the production of dilute acetic acid(12 wt%)via petrochemical routes.Meanwhile,the total capital investment,total product cost,and cash flowsheet were provided in the techno-economic analysis.Then,the net present value,internal rate of return,and dynamic payback period of the production process were evaluated.The findings indicated that while this production process is cost-effective,it might not be economically attractive or could generate investment risks.An increase in the added value of the wood vinegar and the activated carbon could remarkably improve the economic feasibility of this production process.展开更多
Carbon dioxide(CO_(2))emissions from the road sector have attracted increasing attention in current years.This paper attempted to provide a systematic review of the existing research efforts on road life-cycle CO_(2)e...Carbon dioxide(CO_(2))emissions from the road sector have attracted increasing attention in current years.This paper attempted to provide a systematic review of the existing research efforts on road life-cycle CO_(2)emissions by analyzing the system’s boundary division,identifying the CO_(2)emission contributions of each life-cycle phase,listing major emission contributors,exploring related emission reduction technologies,and giving directions for future development.The research showed that the road life cycle is usually divided into five phases:material production,construction,use,maintenance and end-of-life(EOL)phases.The use phase and the initial construction stage(including material production and construction phases)contributed the most CO_(2)emissions during the road life cycle.In detail,the production of cement,asphalt and steel were the three main emission contributors in the material production phase.The pavement roughness,albedo,and concrete carbonation were the main factors affecting emissions in the use phase.In addition,emission reduction technologies such as using recycled materials and recycling techniques,lowering mixing temperature,and equipment energy substitution were commonly used to reduce emissions from material production and construction phases.The application of emerging technologies such as carbon capture and storage,carbon sink,and the use of hydrogen,solar and photovoltaic in the road sector may have emission reduction potentials and should be highlighted more in future studies.展开更多
Optimal application of pavement preservation or preventive maintenance is critical for highway agencies to allocate the limited budget for different treatments. This study developed an integrated life-cycle cost analy...Optimal application of pavement preservation or preventive maintenance is critical for highway agencies to allocate the limited budget for different treatments. This study developed an integrated life-cycle cost analysis (LCCA) model to quantify the impact of pavement preservation on agency cost and vehicle operation cost (VOC) and analyzed the optimal timing of preservation treatments. The international roughness index (IRI) data were extracted from the long-term pavement performance (LTPP) program specific pavement studies 3 (SPS-3) to determine the long-term effectiveness of preservation treatments on IRI deterioration. The traffic loading and the initial IRI value significantly affects life extension and the benefit of agency cost caused by pavement preservation. The benefit in VOC is one to two orders greater in magnitude as compared to the benefit in agency cost. The optimal timing calculated based on VOC is always earlier than the optimal timing calculated based on agency cost. There are considerable differences among the optimal timing of three preservation treatments.展开更多
The LanzaTech process can convert carbon monoxide-containing gases produced by industries, such as steel manufacturing, into valuable fuel products. The life-cycle analysis (LCA) of energy use and greenhouse gas emi...The LanzaTech process can convert carbon monoxide-containing gases produced by industries, such as steel manufacturing, into valuable fuel products. The life-cycle analysis (LCA) of energy use and greenhouse gas emissions from the LanzaTech process has been developed for a Chinese setting using the original Tsinghua China Automotive LCA model along with a customized module developed principally for the process. The LCA results demonstrate that LanzaTech gas-to-liquid (GTL) processing in China's steel manufacturing is favorable in terms of life-cycle fossil energy and can reduce greenhouse gas emissions by approximately 50% compared with the conventional petroleum gasoline. The LanzaTech process, therefore, shows advantages in both energy-savings and a reduction in greenhouse gas emissions when compared with most bio-ethanol production pathways in China.展开更多
Allocation,dereferencing,and freeing of memory data in kernels are coherently linked.There widely exist real cases where the correctness of memory is compromised.This incorrectness in kernel memory brings about signif...Allocation,dereferencing,and freeing of memory data in kernels are coherently linked.There widely exist real cases where the correctness of memory is compromised.This incorrectness in kernel memory brings about significant security issues,e.g.,information leaking.Though memory allocation,dereferencing,and freeing are closely related,previous work failed to realize they are closely related.In this paper,we study the life-cycle of kernel memory,which consists of allocation,dereferencing,and freeing.Errors in them are called memory life-cycle(MLC)bugs.We propose an in-depth study of MLC bugs and implement a memory life-cycle bug sanitizer(MEBS)for MLC bug detection.Utilizing an interprocedural global call graph and novel identification approaches,MEBS can reveal memory allocation,dereferencing,and freeing sites in kernels.By constructing a modified define-use chain and examining the errors in the life-cycle,MLC bugs can be identified.Moreover,the experimental results on the latest kernels demonstrate that MEBS can effectively detect MLC bugs,and MEBS can be scaled to different kernels.More than 100 new bugs are exposed in Linux and FreeBSD,and 12 common vulnerabilities and exposures(CVE)are assigned.展开更多
In this article, the fragility of reinforced concrete and steel structures in Bucharest, a city of high seismic hazard, designed using the recent building codes in Romania, is assessed. A total of 24 reinforced concre...In this article, the fragility of reinforced concrete and steel structures in Bucharest, a city of high seismic hazard, designed using the recent building codes in Romania, is assessed. A total of 24 reinforced concrete and steel structures with heights varying from five stories to 13 stories were analyzed. Their seismic fragility was evaluated using two procedures from the literature. In the first procedure(SPO2 FRAG), the fragility was derived based on the pushover curves using the SPO2 IDA algorithm, while in the second procedure(FRACAS), the fragility was derived from nonlinear time-history analyses. The analyzed structures were designed for three levels of peak ground accelerations, corresponding to mean return periods of 100,225, and 475 years. Subsequently, the damage assessment of the analyzed structures was performed using ground motions generated from a Monte-Carlo simulated earthquake catalogue for the Vrancea intermediate-depth seismic source. The damage degrees that were estimated using the SPO2 FRAG approach are higher than those estimated using the FRACAS approach. The life-cycle analysis of the structures shows that a further increase of the design peak ground acceleration for Bucharest is feasible from an economic point of view using the SPO2 FRAG results.However, based on the FRACAS results, the opposite conclusion can be drawn. Finally, generic lognormal fragility functions are proposed as a function of building height and structural system.展开更多
In this paper, a life-cycle model with retirement is set up to study how an individual chooses the optimal retiring age on account of wage growth rate, longevity and healthy state. It is proved that there exists optim...In this paper, a life-cycle model with retirement is set up to study how an individual chooses the optimal retiring age on account of wage growth rate, longevity and healthy state. It is proved that there exists optimal retiring age under given conditions. The numerical simulations are given to show how wage growth rate, longevity and healthy state affect retiring age.展开更多
Water is an essential resource for agriculture and the majority of land is irrigated through borewells or wells.The power requirement for an irrigation pump motor is fed by the on-grid power supply but the availabilit...Water is an essential resource for agriculture and the majority of land is irrigated through borewells or wells.The power requirement for an irrigation pump motor is fed by the on-grid power supply but the availability of electricity in rural areas is still questionable.With rising concerns about global warming and the rise in carbon footprints,it is necessary to choose clean and green energy,thereby attaining self-sustainable life.India receives yearly a mean solar irradiation of 6.5 kWh/m^(2)day.Hence,a solar photovoltaic-water-pumping system(SPV-WPS)is a suitable alternative to grid energy;thereby,the farmers would generate electricity through the solar photovoltaic system and become self-sufficient in their energy needs.In this paper,two different agricultural fields in Tamil Nadu,India that deploy flood irrigation and drip irrigation are taken as a case study.The paper discusses the concerns on the use of grid power and their carbon footprint,design and simulation of 4-and 5.5-kW SPV-WPSs using PVsyst 7.1.1,and the advantages of using SPV-WPSs and life-cycle cost analysis on different use cases.The Government of India has introduced a special scheme to promote the installation of SPV-WPSs by offering attractive incentives through PM-Kisan Urja Suraksha evam Utthaan Mahabhiyan(KUSUM)yojana.The results of the case study show that with the use of SPV-WPSs,either with or without subsidy,the farmer could gain a minimum of 250%on the investment with a project lifetime of 25 years.展开更多
The life-cycle assessment method,which originates from general products and services,has gradually come to be applied to investigations of the life-cycle carbon emissions(LCCE)of buildings.A literature review was cond...The life-cycle assessment method,which originates from general products and services,has gradually come to be applied to investigations of the life-cycle carbon emissions(LCCE)of buildings.A literature review was conducted to clarify LCCE implications,calculations,and reductions in the context of buildings.A total of 826 global building carbon emission calculation cases were obtained from 161 studies based on the framework of the building life-cycle stage division stipulated by ISO 21930 and the basic principles of the emission factor(EF)approach.The carbon emission calculation methods and results are discussed herein,based on the modules of production,construction,use,end-of-life,and supplementary benefits.According to the hotspot distribution of a building’s carbon emissions,carbon reduction strategies are classified into six groups for technical content and benefits analysis,including reducing the activity data pertaining to building materials and energy,reducing the carbon EFs of the building materials and energy,and exploiting the advantages of supplementary benefits.The research gaps and challenges in current building LCCE studies are summarized in terms of research goals and ideas,calculation methods,basic parameters,and carbon reduction strategies;development suggestions are also proposed.展开更多
The lifecycle greenhouse gas(GHG)emissions(Well-to-Wake)from maritime transport must be reduced by at least 50%in absolute values by 2050 to contribute to the ambitions of the Paris Agreement(2015).A transition from c...The lifecycle greenhouse gas(GHG)emissions(Well-to-Wake)from maritime transport must be reduced by at least 50%in absolute values by 2050 to contribute to the ambitions of the Paris Agreement(2015).A transition from conventional fuels to alternative fuels with zero or lower GHG emissions is viewed as the most promising avenue to reach the GHG reductions.Whereas GHG and toxic pollutants emitted from the use of fossil fuels(heavy fuel oil(HFO)and marine gas/diesel oil(MGO/MDO))are generally well understood,the emissions associated with the new fuel options are only now being measured and communicated.This review provides an outlook on fuels that could help shipping respond to the decarbonization effort including Liquefied Petroleum Gas(LPG),Liquefied Natural Gas(LNG),methanol,ammonia,and hydrogen.A quantification of the pollutants associated from the use of these fuels is provided and challenges and barriers to their uptake are discussed.展开更多
There have been many studies on life cycle assessment in sewage treatment,but there are scarce few studies on the treatment of industrial wastewater in combination with advanced oxidation technology,especially in cata...There have been many studies on life cycle assessment in sewage treatment,but there are scarce few studies on the treatment of industrial wastewater in combination with advanced oxidation technology,especially in catalytic wet air oxidation(CWAO).There are no cases of using actual industrialized data onto life cycle assessment.This paper uses Simapro 9.0 software to establish a life cycle assessment model for the treatment of high-concentration organic wastewater by CWAO,and comprehensively explains the impact on the environment from three aspects:the construction phase,the operation phase and the demolition phase.In addition,sensitivity analysis and uncertainty analysis were performed.The results showed that the key factors affecting the environment were marine ecotoxicity,mineral resource consumption and global warming,the operation stage had the greatest impact on the environment,which was related to high power consumption during operation and emissions from the treatment process.Sensitivity analysis showed that electricity consumption has the greatest impact on abiotic depletion and freshwater aquatic ecotoxicity,and it also proved that global warming is mainly caused by pollutant emissions during operation phase.Monte Carlo simulations found slightly higher uncertainty for abiotic depletion and toxicity-related impact categories.展开更多
Cybersecurity increasingly relies on machine learning(ML)models to respond to and detect attacks.However,the rapidly changing data environment makes model life-cycle management after deployment essential.Real-time det...Cybersecurity increasingly relies on machine learning(ML)models to respond to and detect attacks.However,the rapidly changing data environment makes model life-cycle management after deployment essential.Real-time detection of drift signals from various threats is fundamental for effectively managing deployed models.However,detecting drift in unsupervised environments can be challenging.This study introduces a novel approach leveraging Shapley additive explanations(SHAP),a widely recognized explainability technique in ML,to address drift detection in unsupervised settings.The proposed method incorporates a range of plots and statistical techniques to enhance drift detection reliability and introduces a drift suspicion metric that considers the explanatory aspects absent in the current approaches.To validate the effectiveness of the proposed approach in a real-world scenario,we applied it to an environment designed to detect domain generation algorithms(DGAs).The dataset was obtained from various types of DGAs provided by NetLab.Based on this dataset composition,we sought to validate the proposed SHAP-based approach through drift scenarios that occur when a previously deployed model detects new data types in an environment that detects real-world DGAs.The results revealed that more than 90%of the drift data exceeded the threshold,demonstrating the high reliability of the approach to detect drift in an unsupervised environment.The proposed method distinguishes itself fromexisting approaches by employing explainable artificial intelligence(XAI)-based detection,which is not limited by model or system environment constraints.In conclusion,this paper proposes a novel approach to detect drift in unsupervised ML settings for cybersecurity.The proposed method employs SHAP-based XAI and a drift suspicion metric to improve drift detection reliability.It is versatile and suitable for various realtime data analysis contexts beyond DGA detection environments.This study significantly contributes to theMLcommunity by addressing the critical issue of managing ML models in real-world cybersecurity settings.Our approach is distinguishable from existing techniques by employing XAI-based detection,which is not limited by model or system environment constraints.As a result,our method can be applied in critical domains that require adaptation to continuous changes,such as cybersecurity.Through extensive validation across diverse settings beyond DGA detection environments,the proposed method will emerge as a versatile drift detection technique suitable for a wide range of real-time data analysis contexts.It is also anticipated to emerge as a new approach to protect essential systems and infrastructures from attacks.展开更多
基金National Natural Science Foundation of China under Grant Nos.51921006 and 51725801Fundamental Research Funds for the Central Universities under Grant No.FRFCU5710093320Heilongjiang Touyan Innovation Team Program。
文摘Reinforcement corrosion is the main cause of performance deterioration of reinforced concrete(RC)structures.Limited research has been performed to investigate the life-cycle cost(LCC)of coastal bridge piers with nonuniform corrosion using different materials.In this study,a reliability-based design optimization(RBDO)procedure is improved for the design of coastal bridge piers using six groups of commonly used materials,i.e.,normal performance concrete(NPC)with black steel(BS)rebar,high strength steel(HSS)rebar,epoxy coated(EC)rebar,and stainless steel(SS)rebar(named NPC-BS,NPC-HSS,NPC-EC,and NPC-SS,respectively),NPC with BS with silane soakage on the pier surface(named NPC-Silane),and high-performance concrete(HPC)with BS rebar(named HPC-BS).First,the RBDO procedure is improved for the design optimization of coastal bridge piers,and a bridge is selected to illustrate the procedure.Then,reliability analysis of the pier designed with each group of materials is carried out to obtain the time-dependent reliability in terms of the ultimate and serviceability performances.Next,the repair time of the pier is predicted based on the time-dependent reliability indices.Finally,the time-dependent LCCs for the pier are obtained for the selection of the optimal design.
基金supported by the National Natural Science Foundation of China(Nos.52034009 and 51974319)the Yue Qi Distinguished Scholar Project(No.2020JCB01)。
文摘The quantitative determination and evaluation of rock brittleness are crucial for the estimation of excavation efficiency and the improvement of hydraulic fracturing efficiency.Therefore,a“three-stage”triaxial loading and unloading stress path is designed and proposed.Subsequently,six brittleness indices are selected.In addition,the evolution characteristics of the six brittleness indices selected are characterized based on the bedding effect and the effect of confining pressure.Then,the entropy weight method(EWM)is introduced to assign weight to the six brittleness indices,and the comprehensive brittleness index Bcis defined and evaluated.Next,the new brittleness classification standard is determined,and the brittleness differences between the two stress paths are quantified.Finally,compared with the previous evaluation methods,the rationality of the proposed comprehensive brittleness index Bcis also verified.These results indicate that the proposed brittleness index Bccan reflect the brittle characteristics of deep bedded sandstone from the perspective of the whole life-cycle evolution process.Accordingly,the method proposed seems to offer reliable evaluations of the brittleness of deep bedded sandstone in deep engineering practices,although further validation is necessary.
基金supported by the National Natural Science Foundation of China(71732001,51878311,72271106,U21A20151,and 71821001)Engineering Fronts Project(2021-HYZD-5-13)+1 种基金Major Science&Technology Project of Hubei(2020ACA006)China Scholarship Council(202006160115).
文摘During the coronavirus disease 2019 (COVID-19) emergency, many hospitals were built or renovated around the world to meet the challenges posed by the rising number of infected cases. Environmental management in the hospital life cycle is vital in preventing nosocomial infection and includes many infection control procedures. In certain urgent situations, a hospital must be completed quickly, and work process approval and supervision must therefore be accelerated. Thus, many works cannot be checked in detail. This results in a lack of work liability control and increases the difficulty of ensuring the fulfillment of key infection prevention measures. This study investigates how blockchain technology can transform the work quality inspection workflow to assist in nosocomial infection control under a fast delivery requirement. A blockchain-based life-cycle environmental management framework is proposed to track the fulfillment of crucial infection control measures in the design, construction, and operation stages of hospitals. The proposed framework allows for work quality checking after the work is completed, when some work cannot be checked on time. Illustrative use cases are selected to demonstrate the capabilities of the developed solution. This study provides new insights into applying blockchain technology to address the challenge of environmental management brought by rapid delivery requirements.
基金Supported by:Fundamental Research Funds for the Central Universities under Grant No.2021QN1022。
文摘Engineering structures may be exposed to one or more extreme hazards during their life-cycles.Current structural design specifications usually treat multiple hazards separately in designing structures and there is a limited probabilistic basis on extreme load combinations.Additionally,the performance of engineering structures will be deteriorated by the aggressive environments during their service periods,such as chloride attack,concrete carbonation,and wind-induced fatigue.This study presents a probabilistic methodology to assess the time-dependent failure probability of RC bridges with chloride-induced corrosion under the multiple hazards of earthquakes and strong winds.The loss of cross-section area of reinforcements and the reduction in strength of reinforcing steel and concrete cover induced by the chloride attack are considered.Moreover,the Poisson model is employed to obtain the occurrence probabilities of the individual and concurrent earthquake and strong wind events.The convolution integral is used to determine the joint probability distribution of combined load effects under simultaneous earthquakes and strong winds.Numerical results indicate that the structural failure probability under multiple hazards increases significantly during the bridge′s life-cycle due to the chloride corrosion effect.The contribution of each hazard event on the total structural failure probability varies with time.Thus,neglecting the combined influences of multiple hazards and chloride-induced corrosion may bring erroneous predictions in failure probability estimates of RC bridges.
基金Under the auspices of the National Natural Science Foundation of China(No.41101567)
文摘As the construction sector is a major energy consumer and thus a significant contributor of CO_2 emissions in China,it is important to consider carbon reduction in this industry.This study analyzed six life-cycle stages and calculated the life-cycle CO_2 emissions of the construction sector in 30 Chinese provincial jurisdictions to understand the disparity among them.Results show that building materials production was the key stage for carbon reduction in the construction sector,followed by the building operation stage.External variables,e.g.,economic growth,industrial structure,urbanization,price fluctuation,and marketization,were significantly correlated with the emission intensity of the construction sector.Specifically,economic growth exhibited an inverted U-shaped relation with CO_2 emissions per capita and per area during the period examined.Secondary industry and land urbanization were negatively correlated with CO_2 emission intensity indicators from the construction sector,whereas tertiary industry and urbanization were positively correlated.Price indices and marketization had negative effects on CO_2 emission intensity.The policy implications of our findings are that cleaner technologies should be encouraged for cement providers,and green purchasing rules for the construction sector should also be established.Pricing tools(e.g.,resource taxes)could help to adjust the demand for raw materials and energy.
文摘With the continuous development of urban public transportation, the harmful GHG emissions and pollutants generated by itself and the consequent issues such as the losses of residents’ health, economic value and residents’ welfare have become the focus of social attention. In order to study the impacts of promoting new energy vehicles on public transportation pollution mitigation and residents’ health benefits, this paper adopts the LEAP model to build some scenarios that fulfill different development needs to quantitatively analyze the ownership of new energy buses, the reduction of pollutants and the losses of residents’ health welfare. It is concluded that promoting new energy buses comprehensively can significantly reduce the emissions of atmospheric pollutants and the economic losses of residents’ health, but cannot fully realize the targets of greenhouse gas reduction under Life Cycle Analysis.
基金supported by the Consulting Research Project of the Chinese Academy of Engineering(Grant No.2019-XZ-51).
文摘The hydrogen fuel cell vehicle is rapidly developing in China for carbon reduction and neutrality.This paper evaluated the life-cycle cost and carbon emission of hydrogen energy via lots of field surveys,including hydrogen production and packing in chlor-alkali plants,transport by tube trailers,storage and refueling in hydrogen refueling stations(HRSs),and application for use in two different cities.It also conducted a comparative study for battery electric vehicles(BEVs)and internal combustion engine vehicles(ICEVs).The result indicates that hydrogen fuel cell vehicle(FCV)has the best environmental performance but the highest energy cost.However,a sufficient hydrogen supply can significantly reduce the carbon intensity and FCV energy cost of the current system.The carbon emission for FCV application has the potential to decrease by 73.1%in City A and 43.8%in City B.It only takes 11.0%–20.1%of the BEV emission and 8.2%–9.8%of the ICEV emission.The cost of FCV driving can be reduced by 39.1%in City A.Further improvement can be obtained with an economical and“greener”hydrogen production pathway.
基金The authors wish to express their gratitude for the financial supported by the National Key Research and Development Program of China(Grant No.2018YFE0127000)the Young Tip-top Talent Project of Science and Technology Innovation by State Forestry and Grassland Administration of China(Grant No.2019132616)+1 种基金the Agricultural Science and Technology Innovation Drive Project of Shaanxi Province(Grant Nos.NYKJ-2021-YLXN15,K3030821093)the Forestry Science and Technology Development Project by State Forestry and Grassland Administration of China(Grant No.KJZXZZ2019005).
文摘This research undertook a case study of the life-cycle assessment and techno-economic analysis of the slow pyrolysis of Eucommia stem for the production of wood vinegar and activated carbon.The results showed that the production of one ton of wood vinegar via the slow pyrolysis of Eucommia stem show comparatively low global warming potential(2.37×10^(2) kg CO_(2) eq),primary energy demand(3.16×10^(3) MJ),acidification potential(2.19 kg SO2 eq),antimony depletion potential(3.86×10^(–4) kg antimony eq),and ozone depletion potential(7.46×10^(–6) kg CFC-11 eq)and was more environmentally friendly than the production of dilute acetic acid(12 wt%)via petrochemical routes.Meanwhile,the total capital investment,total product cost,and cash flowsheet were provided in the techno-economic analysis.Then,the net present value,internal rate of return,and dynamic payback period of the production process were evaluated.The findings indicated that while this production process is cost-effective,it might not be economically attractive or could generate investment risks.An increase in the added value of the wood vinegar and the activated carbon could remarkably improve the economic feasibility of this production process.
基金supported by the National Natural Science Foundation of China(Grant Nos.51878062,52102390 and 52002032)the Natural Science Foundation of Shaanxi Province(Grant No.2022JQ-527)the Fundamental Research Funds for the Central Universities(Grant Nos.300102342501 and 300102342517)
文摘Carbon dioxide(CO_(2))emissions from the road sector have attracted increasing attention in current years.This paper attempted to provide a systematic review of the existing research efforts on road life-cycle CO_(2)emissions by analyzing the system’s boundary division,identifying the CO_(2)emission contributions of each life-cycle phase,listing major emission contributors,exploring related emission reduction technologies,and giving directions for future development.The research showed that the road life cycle is usually divided into five phases:material production,construction,use,maintenance and end-of-life(EOL)phases.The use phase and the initial construction stage(including material production and construction phases)contributed the most CO_(2)emissions during the road life cycle.In detail,the production of cement,asphalt and steel were the three main emission contributors in the material production phase.The pavement roughness,albedo,and concrete carbonation were the main factors affecting emissions in the use phase.In addition,emission reduction technologies such as using recycled materials and recycling techniques,lowering mixing temperature,and equipment energy substitution were commonly used to reduce emissions from material production and construction phases.The application of emerging technologies such as carbon capture and storage,carbon sink,and the use of hydrogen,solar and photovoltaic in the road sector may have emission reduction potentials and should be highlighted more in future studies.
文摘Optimal application of pavement preservation or preventive maintenance is critical for highway agencies to allocate the limited budget for different treatments. This study developed an integrated life-cycle cost analysis (LCCA) model to quantify the impact of pavement preservation on agency cost and vehicle operation cost (VOC) and analyzed the optimal timing of preservation treatments. The international roughness index (IRI) data were extracted from the long-term pavement performance (LTPP) program specific pavement studies 3 (SPS-3) to determine the long-term effectiveness of preservation treatments on IRI deterioration. The traffic loading and the initial IRI value significantly affects life extension and the benefit of agency cost caused by pavement preservation. The benefit in VOC is one to two orders greater in magnitude as compared to the benefit in agency cost. The optimal timing calculated based on VOC is always earlier than the optimal timing calculated based on agency cost. There are considerable differences among the optimal timing of three preservation treatments.
基金The project is co-supported by the National Natural Science Foundation of China (Grant Nos. 71041028, 71103109 and 71073095), the National Social Science Foundation of China (Grant No. 09&ZD029), MOE Project of Key Research Institute of Humanities and Social Sciences at Universities in China (No. 2009JJD790029) and the CAERC program (Tsinghua/GM/SAIC-China).
文摘The LanzaTech process can convert carbon monoxide-containing gases produced by industries, such as steel manufacturing, into valuable fuel products. The life-cycle analysis (LCA) of energy use and greenhouse gas emissions from the LanzaTech process has been developed for a Chinese setting using the original Tsinghua China Automotive LCA model along with a customized module developed principally for the process. The LCA results demonstrate that LanzaTech gas-to-liquid (GTL) processing in China's steel manufacturing is favorable in terms of life-cycle fossil energy and can reduce greenhouse gas emissions by approximately 50% compared with the conventional petroleum gasoline. The LanzaTech process, therefore, shows advantages in both energy-savings and a reduction in greenhouse gas emissions when compared with most bio-ethanol production pathways in China.
基金supported by the National High-Level Personnel for Defense Technology Program of China under Grant No.2017-JCJQ-ZQ-013the National Natural Science Foundation of China under Grant Nos.61902405 and 61902412+2 种基金the Natural Science Foundation of Hunan Province of China under Grant No.2021JJ40692the Parallel and Distributed Processing Research Foundation under Grant No.6142110190404the Research Project of National University of Defense Technology under Grant Nos.ZK20-09 and ZK20-17.
文摘Allocation,dereferencing,and freeing of memory data in kernels are coherently linked.There widely exist real cases where the correctness of memory is compromised.This incorrectness in kernel memory brings about significant security issues,e.g.,information leaking.Though memory allocation,dereferencing,and freeing are closely related,previous work failed to realize they are closely related.In this paper,we study the life-cycle of kernel memory,which consists of allocation,dereferencing,and freeing.Errors in them are called memory life-cycle(MLC)bugs.We propose an in-depth study of MLC bugs and implement a memory life-cycle bug sanitizer(MEBS)for MLC bug detection.Utilizing an interprocedural global call graph and novel identification approaches,MEBS can reveal memory allocation,dereferencing,and freeing sites in kernels.By constructing a modified define-use chain and examining the errors in the life-cycle,MLC bugs can be identified.Moreover,the experimental results on the latest kernels demonstrate that MEBS can effectively detect MLC bugs,and MEBS can be scaled to different kernels.More than 100 new bugs are exposed in Linux and FreeBSD,and 12 common vulnerabilities and exposures(CVE)are assigned.
文摘In this article, the fragility of reinforced concrete and steel structures in Bucharest, a city of high seismic hazard, designed using the recent building codes in Romania, is assessed. A total of 24 reinforced concrete and steel structures with heights varying from five stories to 13 stories were analyzed. Their seismic fragility was evaluated using two procedures from the literature. In the first procedure(SPO2 FRAG), the fragility was derived based on the pushover curves using the SPO2 IDA algorithm, while in the second procedure(FRACAS), the fragility was derived from nonlinear time-history analyses. The analyzed structures were designed for three levels of peak ground accelerations, corresponding to mean return periods of 100,225, and 475 years. Subsequently, the damage assessment of the analyzed structures was performed using ground motions generated from a Monte-Carlo simulated earthquake catalogue for the Vrancea intermediate-depth seismic source. The damage degrees that were estimated using the SPO2 FRAG approach are higher than those estimated using the FRACAS approach. The life-cycle analysis of the structures shows that a further increase of the design peak ground acceleration for Bucharest is feasible from an economic point of view using the SPO2 FRAG results.However, based on the FRACAS results, the opposite conclusion can be drawn. Finally, generic lognormal fragility functions are proposed as a function of building height and structural system.
基金Supported by the National Natural Science Foundation of China(71271158)
文摘In this paper, a life-cycle model with retirement is set up to study how an individual chooses the optimal retiring age on account of wage growth rate, longevity and healthy state. It is proved that there exists optimal retiring age under given conditions. The numerical simulations are given to show how wage growth rate, longevity and healthy state affect retiring age.
文摘Water is an essential resource for agriculture and the majority of land is irrigated through borewells or wells.The power requirement for an irrigation pump motor is fed by the on-grid power supply but the availability of electricity in rural areas is still questionable.With rising concerns about global warming and the rise in carbon footprints,it is necessary to choose clean and green energy,thereby attaining self-sustainable life.India receives yearly a mean solar irradiation of 6.5 kWh/m^(2)day.Hence,a solar photovoltaic-water-pumping system(SPV-WPS)is a suitable alternative to grid energy;thereby,the farmers would generate electricity through the solar photovoltaic system and become self-sufficient in their energy needs.In this paper,two different agricultural fields in Tamil Nadu,India that deploy flood irrigation and drip irrigation are taken as a case study.The paper discusses the concerns on the use of grid power and their carbon footprint,design and simulation of 4-and 5.5-kW SPV-WPSs using PVsyst 7.1.1,and the advantages of using SPV-WPSs and life-cycle cost analysis on different use cases.The Government of India has introduced a special scheme to promote the installation of SPV-WPSs by offering attractive incentives through PM-Kisan Urja Suraksha evam Utthaan Mahabhiyan(KUSUM)yojana.The results of the case study show that with the use of SPV-WPSs,either with or without subsidy,the farmer could gain a minimum of 250%on the investment with a project lifetime of 25 years.
基金supported by the National Natural Science Foundation of China(51825802,52130803,52278020,and 72374121)the China National Key Research and Development Program(2018YFE0106100)+1 种基金the China Postdoctoral Science Foundation(2022M711815)the New Cornerstone Science Foundation through the XPLORER PRIZE.
文摘The life-cycle assessment method,which originates from general products and services,has gradually come to be applied to investigations of the life-cycle carbon emissions(LCCE)of buildings.A literature review was conducted to clarify LCCE implications,calculations,and reductions in the context of buildings.A total of 826 global building carbon emission calculation cases were obtained from 161 studies based on the framework of the building life-cycle stage division stipulated by ISO 21930 and the basic principles of the emission factor(EF)approach.The carbon emission calculation methods and results are discussed herein,based on the modules of production,construction,use,end-of-life,and supplementary benefits.According to the hotspot distribution of a building’s carbon emissions,carbon reduction strategies are classified into six groups for technical content and benefits analysis,including reducing the activity data pertaining to building materials and energy,reducing the carbon EFs of the building materials and energy,and exploiting the advantages of supplementary benefits.The research gaps and challenges in current building LCCE studies are summarized in terms of research goals and ideas,calculation methods,basic parameters,and carbon reduction strategies;development suggestions are also proposed.
文摘The lifecycle greenhouse gas(GHG)emissions(Well-to-Wake)from maritime transport must be reduced by at least 50%in absolute values by 2050 to contribute to the ambitions of the Paris Agreement(2015).A transition from conventional fuels to alternative fuels with zero or lower GHG emissions is viewed as the most promising avenue to reach the GHG reductions.Whereas GHG and toxic pollutants emitted from the use of fossil fuels(heavy fuel oil(HFO)and marine gas/diesel oil(MGO/MDO))are generally well understood,the emissions associated with the new fuel options are only now being measured and communicated.This review provides an outlook on fuels that could help shipping respond to the decarbonization effort including Liquefied Petroleum Gas(LPG),Liquefied Natural Gas(LNG),methanol,ammonia,and hydrogen.A quantification of the pollutants associated from the use of these fuels is provided and challenges and barriers to their uptake are discussed.
基金supported by National Natural Science Foundation of China(52100072,52100213)the Fundamental Research FundsfortheCentralUniversities(JZ2021HGTA0159,JZ2021HGQA0212)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA21021101)the Scientific Research Common Program of Beijing Municipal Commission of Education(KM202010017006)the Beijing Natural Science Foundation(8214056)。
文摘There have been many studies on life cycle assessment in sewage treatment,but there are scarce few studies on the treatment of industrial wastewater in combination with advanced oxidation technology,especially in catalytic wet air oxidation(CWAO).There are no cases of using actual industrialized data onto life cycle assessment.This paper uses Simapro 9.0 software to establish a life cycle assessment model for the treatment of high-concentration organic wastewater by CWAO,and comprehensively explains the impact on the environment from three aspects:the construction phase,the operation phase and the demolition phase.In addition,sensitivity analysis and uncertainty analysis were performed.The results showed that the key factors affecting the environment were marine ecotoxicity,mineral resource consumption and global warming,the operation stage had the greatest impact on the environment,which was related to high power consumption during operation and emissions from the treatment process.Sensitivity analysis showed that electricity consumption has the greatest impact on abiotic depletion and freshwater aquatic ecotoxicity,and it also proved that global warming is mainly caused by pollutant emissions during operation phase.Monte Carlo simulations found slightly higher uncertainty for abiotic depletion and toxicity-related impact categories.
基金supported by the Institute of Information and Communications Technology Planning and Evaluation(IITP)grant funded by the Korean government(MSIT)(No.2022-0-00089,Development of clustering and analysis technology to identify cyber attack groups based on life cycle)the Institute of Civil Military Technology Cooperation funded by the Defense Acquisition Program Administration and Ministry of Trade,Industry and Energy of Korean government under Grant No.21-CM-EC-07.
文摘Cybersecurity increasingly relies on machine learning(ML)models to respond to and detect attacks.However,the rapidly changing data environment makes model life-cycle management after deployment essential.Real-time detection of drift signals from various threats is fundamental for effectively managing deployed models.However,detecting drift in unsupervised environments can be challenging.This study introduces a novel approach leveraging Shapley additive explanations(SHAP),a widely recognized explainability technique in ML,to address drift detection in unsupervised settings.The proposed method incorporates a range of plots and statistical techniques to enhance drift detection reliability and introduces a drift suspicion metric that considers the explanatory aspects absent in the current approaches.To validate the effectiveness of the proposed approach in a real-world scenario,we applied it to an environment designed to detect domain generation algorithms(DGAs).The dataset was obtained from various types of DGAs provided by NetLab.Based on this dataset composition,we sought to validate the proposed SHAP-based approach through drift scenarios that occur when a previously deployed model detects new data types in an environment that detects real-world DGAs.The results revealed that more than 90%of the drift data exceeded the threshold,demonstrating the high reliability of the approach to detect drift in an unsupervised environment.The proposed method distinguishes itself fromexisting approaches by employing explainable artificial intelligence(XAI)-based detection,which is not limited by model or system environment constraints.In conclusion,this paper proposes a novel approach to detect drift in unsupervised ML settings for cybersecurity.The proposed method employs SHAP-based XAI and a drift suspicion metric to improve drift detection reliability.It is versatile and suitable for various realtime data analysis contexts beyond DGA detection environments.This study significantly contributes to theMLcommunity by addressing the critical issue of managing ML models in real-world cybersecurity settings.Our approach is distinguishable from existing techniques by employing XAI-based detection,which is not limited by model or system environment constraints.As a result,our method can be applied in critical domains that require adaptation to continuous changes,such as cybersecurity.Through extensive validation across diverse settings beyond DGA detection environments,the proposed method will emerge as a versatile drift detection technique suitable for a wide range of real-time data analysis contexts.It is also anticipated to emerge as a new approach to protect essential systems and infrastructures from attacks.