In order to explore the serviceability and reinforcement of CaCO3 whisker in portland cement matrix, the durability of CaCO3 whisker and effect of low whisker content（0%-4.0%） on the working performance and mechanic...In order to explore the serviceability and reinforcement of CaCO3 whisker in portland cement matrix, the durability of CaCO3 whisker and effect of low whisker content（0%-4.0%） on the working performance and mechanical properties of portland cement were investigated. The experimental results show that CaCO3 whiskers have a good stability and serviceability in cement, and should not significantly alter the rheological properties of the cement paste. The flexural and compressive strength of portland cement reinforced by CaCO3 whiskers was increased by 33.3% and 12.83%, respectively.展开更多
The serviceability of water supply networks(WSNs)under seismic loads has significant importance for estimating the probable losses and the impact of diminished functionality on affected communities.The innovation pres...The serviceability of water supply networks(WSNs)under seismic loads has significant importance for estimating the probable losses and the impact of diminished functionality on affected communities.The innovation presented in this paper is suggesting a new strategy to evaluate the seismic serviceability of WSNs,utilizing their operational physical mechanism.On one hand,this method can obtain the seismic serviceability of each node as well as entire WSNs.On the other hand,this method can dynamically reflect the propagation of randomness from ground motions to WSNs.First,a finite element model is established to capture the seismic response of buried pipe networks,and a leakage model is suggested to obtain the leakage area of WSNs.Second,the transient flow analysis of WSNs with or without leakage is derived to obtain dynamic water flow and pressure.Third,the seismic serviceability of WSNs is analyzed based on the probability density evolution method(PDEM).Finally,the seismic serviceability of a real WSN in Mianzhu city is assessed to illustrate the method.The case study shows that randomness from the ground motions can obviously affect the leakage state and the probability density of the nodal head during earthquakes.展开更多
The increasing strength of new structural materials and the span of new structures, accompanied by aesthetic requirements for greater slenderness, are resulting in more applications of long-span structures. In this pa...The increasing strength of new structural materials and the span of new structures, accompanied by aesthetic requirements for greater slenderness, are resulting in more applications of long-span structures. In this paper, serviceability control technology and its design theory are studied. First, a novel tuned mass damper （TMD） with controllable stiffness is developed. Second, methods for modeling human-induced loads are proposed, including standing up, walking, jumping and running, and an analysis method for long-span floor response is proposed based on a finite element model. Third, a design method for long-span floors installed with a multiple TMD （MTMD） system considering human comfort is introduced, largely based on a study of existing literature. Finally, a design, analysis and field test is conducted using several large scale buildings in China including the Beijing Olympic Park National Conference Center, Changsha New Railway Station and the Xi＇an Northern Railway Station. The analytical and field test results show that the MTMD system designed using the proposed method is capable of effectively mitigating the vertical vibration of long-span floor structures. The study presented in this paper provides an important reference for the analysis of vibration serviceability of similar long-span floors and design of control system for these structures.展开更多
An extensive experimental and theoretical research study was undertaken to study the vibration serviceability of a long-span prestressed concrete floor system to be used in the lounge of a major airport.Specifically,j...An extensive experimental and theoretical research study was undertaken to study the vibration serviceability of a long-span prestressed concrete floor system to be used in the lounge of a major airport.Specifically,jumping impact tests were carried out to obtain the floor’s modal parameters,followed by an analysis of the distribution of peak accelerations.Running tests were also performed to capture the acceleration responses.The prestressed concrete floor was found to have a low fundamental natural frequency（≈8.86 Hz）corresponding to the average modal damping ratio of≈2.17%.A coefficients plate with simply-supported edges.The calculated analytical results（natural frequencies and root-mean-square acceleration）agree well with the experimental ones.The analytical approach is thus validated.展开更多
The reliability and deterministic analyses of wood-cored stiffened deep cement mixing and deep cement mixing column-supported embankments(referred to as WSCSE and DCSE,respectively)considering serviceability limit sta...The reliability and deterministic analyses of wood-cored stiffened deep cement mixing and deep cement mixing column-supported embankments(referred to as WSCSE and DCSE,respectively)considering serviceability limit state requirements are presented in this paper.Random field theory was used to simulate the spatial variability of soilcement mixing(SCM)material in which the adaptive Kriging Monte Carlo simulation was adopted to estimate the failure probability of a columnsupported embankment(CSE)system.A new method for stochastically generating random values of unconfined compressive strength(qu)and the ratio(Ru)between the undrained elastic modulus and qu of SCM material based on statistical correlation data is proposed.Reliability performance of CSEs concerning changes in the mean(μ),coefficient of variation(CoV),and vertical spatial correlation length(θv)of qu and Ru are presented and discussed.The obtained results indicate that WSCSE can provide a significantly higher reliability level and can tolerate more SCM material spatial variability than DCSE.Some performance of DCSE and WSCSE,which can be considered satisfactory in a deterministic framework,cannot guarantee an acceptable reliability level from a probabilistic viewpoint.This highlights the importance and necessity of employing reliability analyses for the design of CSEs.Moreover,consideration of only μ and CoV of qu seems to be sufficient for reliability analysis of WSCSE while for DCSE,uncertainties regarding the Ru(i.e.both μ and CoV)and θv of qu cannot be ignored.展开更多
The objective is to develop an approach for the determination of the target reliability index for serviceability limit state(SLS) of single piles. This contributes to conducting the SLS reliability-based design(RBD) o...The objective is to develop an approach for the determination of the target reliability index for serviceability limit state(SLS) of single piles. This contributes to conducting the SLS reliability-based design(RBD) of piles. Based on a two-parameter,hyperbolic curve-fitting equation describing the load-settlement relation of piles, the SLS model factor is defined. Then, taking into account the uncertainties of load-settlement model, load and bearing capacity of piles, the formula for computing the SLS reliability index(βsls) is obtained using the mean value first order second moment(MVFOSM) method. Meanwhile, the limit state function for conducting the SLS reliability analysis by the Monte Carlo simulation(MCS) method is established. These two methods are finally applied to determine the SLS target reliability index. Herein, the limiting tolerable settlement(slt) is treated as a random variable. For illustration, four load test databases from South Africa are compiled again to conduct reliability analysis and present the recommended target reliability indices. The results indicate that the MVFOSM method overestimates βsls compared to that computed by the MCS method. Besides, both factor of safety(FS) and slt are key factors influencing βsls, so the combination of FS and βsls is welcome to be used for the SLS reliability analysis of piles when slt is determined. For smaller slt, pile types and soils conditions have significant influence on the SLS target reliability indices; for larger slt, slt is the major factor having influence on the SLS target reliability indices. This proves that slt is the most key parameter for the determination of the SLS target reliability index.展开更多
For further understanding reliability and serviceability of tractor and to furnish scientific and technical theories, based on the promotion and application of it, the following experiments and statistical analysis on...For further understanding reliability and serviceability of tractor and to furnish scientific and technical theories, based on the promotion and application of it, the following experiments and statistical analysis on reliability （reliability and MTBF） serviceability （service and MTTR） of Donfanghong-1002 and Dongfanghong-802 were conducted. The result showed that the intervals of average troubles of these two tractors were 182.62 h and 160.2 h, respectively, and the weakest assembly of them was engine part.展开更多
This article presented a new data fusion approach for reasonably predicting dynamic serviceability reliability of the long-span bridge girder.Firstly,multivariate Bayesian dynamic linear model(MBDLM)considering dynami...This article presented a new data fusion approach for reasonably predicting dynamic serviceability reliability of the long-span bridge girder.Firstly,multivariate Bayesian dynamic linear model(MBDLM)considering dynamic correlation among the multiple variables is provided to predict dynamic extreme deflections;secondly,with the proposed MBDLM,the dynamic correlation coefficients between any two performance functions can be predicted;finally,based on MBDLM and Gaussian copula technique,a new data fusion method is given to predict the serviceability reliability of the long-span bridge girder,and the monitoring extreme deflection data from an actual bridge is provided to illustrated the feasibility and application of the proposed method.展开更多
This paper provides innovative and effective instruments for the simplified analysis of serviceability limit states for pitched, kinked, and tapered GLT beams. Specifically, formulas for the evaluation of maximal hori...This paper provides innovative and effective instruments for the simplified analysis of serviceability limit states for pitched, kinked, and tapered GLT beams. Specifically, formulas for the evaluation of maximal horizontal and vertical displacements are derived from a recently-proposed Timoshenko-like non-prismatic beam model. Thereafter, the paper compares the proposed serviceability analysis formulas with other ones available in literature and with highly-refined 2D FE simulations in order to demonstrate the effectiveness of the proposed instruments. The proposed formulas lead to estimations that lie mainly on the conservative side and the errors are smaller than 10% (exceptionally up to 15%) in almost all of the cases of interest for practitioners. Conversely, the accuracy of the proposed formulas decreases for thick and highly-tapered beams since the beam model behind the proposed formulas cannot tackle local effects (like stress concentrations occurring at bearing and beam apex) that significantly influence the beam behavior for such geometries. Finally, the proposed formulas are more accurate than the ones available in literature since the latter ones often provide non-conservative estimations and errors greater than 20% (up to 120%).展开更多
In Indian mixed traffic, a common scenario is when motorized vehicles, non-motorized vehicles including pedestrians use the same road space. In such conditions, ifPLOS （pedestrian level of service） is measured using...In Indian mixed traffic, a common scenario is when motorized vehicles, non-motorized vehicles including pedestrians use the same road space. In such conditions, ifPLOS （pedestrian level of service） is measured using conventional methods, i.e., considering pedestrians walking on footpath only; leads to unrealistic results as most of the time pedestrians are seen walking on the path dedicated for vehicles, i.e., vehicle-path. The decision making behavior of pedestrians regarding walking on footpath or on vehicle-path is influenced by the quality of footpath as well as the characteristics of traffic on vehicle-path and the presence of vendors in the street. Hardly any research carried out on measuring pedestrians＇ serviceability on road considering pedestrians walking on vehicle-path. This study attempts to estimate the effect of various parameters such as intensity of vehicular traffic on the vehicle-path, presence of street vendors on the vehicle-path, etc., on pedestrians＇ decision of walking on footpath or on vehicle-path based on data collected at two locations in New Delhi, India, by using various statistical methods, especially binary logistic regression. One of the locations is an urban two-lane undivided road with footpath on both sides, a part of National Highway-2, another one is a four-lane divided road with footpath on both sides which is a typical arterial road. It has been found that vendors play a significant role in pedestrians＇ decision making regarding walking on footpath or on vehicle-path. Study proposes a model to measure pedestrians＇ serviceability on a road where pedestrians may be walking on the vehicle-path even in the presence of footpath.展开更多
This paper presents a simplified beam design method for semi-rigid composite frames with vertical loading at the serviceability limit state. Equations were developed to determine the deflections of the composite beam ...This paper presents a simplified beam design method for semi-rigid composite frames with vertical loading at the serviceability limit state. Equations were developed to determine the deflections of the composite beam allowing for both joint flexibility and beam sectional properties, along with a formula for the connection secant stiffness. The equations for the connection stiffness are more accurate than previous equations used because it considers the beam-to-column stiffness ratio and the beam-to-connection stiffness ratio. The equations were validated by the experimental results for two semi-rigid composite frames. The equations agree well with the experimental data because they take into account the actual beam-to-column connections and the composite action between the steel beam and the concrete slab.展开更多
Common mental disorders(CMDs),such as depressive and anxiety disorders,constitute a significant public health problem in low-and middle-income countries,such as India,where they rank among the leading causes of disabi...Common mental disorders(CMDs),such as depressive and anxiety disorders,constitute a significant public health problem in low-and middle-income countries,such as India,where they rank among the leading causes of disability and impaired quality of life.Outcomes are further compromised by a large treatment gap,poor adherence to therapeutic regimens,and high attrition rates.The prevalence and severity of CMDs are disproportionately higher in women.Additionally,structural factors influencing healthcare access,along with sociocultural factors,such as gender-based violence,limited autonomy in healthcare decisions,and greater levels of discrimination and stigma,result in poorer outcomes among women with CMDs.Therefore,there is a pressing need for care packages that are culturally sensitive,gender-responsive,and designed to address these structural and sociocultural factors,as highlighted in the literature from India.展开更多
In Wuhu,urban renewal has not only transformed the development process,but improved people’s lives.DURING the 14th Five-Year Plan period(2021-2025),urban renewal has served as a crucial measure to promote high-qualit...In Wuhu,urban renewal has not only transformed the development process,but improved people’s lives.DURING the 14th Five-Year Plan period(2021-2025),urban renewal has served as a crucial measure to promote high-quality urban development and continuously meet people’s growing aspirations for a better life.Wuhu,in central China’s Anhui Province,has consistently enhanced its urban functions and services to build a modern,people-oriented city that is innovative,livable,beautiful,resilient,and smart.展开更多
The rapid population and land urbanization not only promoted economic development but also affected the ecosystem service value(ESV).In the context of new-type urbanization and green development,it’s essential to inv...The rapid population and land urbanization not only promoted economic development but also affected the ecosystem service value(ESV).In the context of new-type urbanization and green development,it’s essential to investigate the impacts of urbanization on ESV in China.However,a comprehensive and dynamic framework to reveal the relationship between ESV and urbanization processes is lacking.This study adopted multi-source datasets to portray China’s urbanization process by integrating population,land,and economic urbanization,eval-uated the ESV changes of 10 categories by gross ecosystem product(GEP)methods,and explored ESV changes within different urbanization scales and speeds.The results showed rapid urbanization in the population,land,and economic dimensions in China,with a faster process of economic urbanization.The ESV also exhibited an increasing trend,with higher levels in the southeastern coastal regions and lower levels in the northwestern regions.Urbanization had positive impacts on ESV across various research units,but the ESV exhibited heteroge-neous changes across different urbanization scales,speeds,and their interactive effects.The response of ESV to dynamic urbanization processes was influenced by socio-economic,ecological,and policy factors;it is essential to combine targeted measures with general ecological product value realization methods in each unit to maximize social-economic-ecological benefits.展开更多
Human well-being and livelihoods depend on natural ecosystem services(ESs).Following the increment of population,ESs have been deteriorated over time.Ultimately,land use/land cover(LULC)changes have a profound impact ...Human well-being and livelihoods depend on natural ecosystem services(ESs).Following the increment of population,ESs have been deteriorated over time.Ultimately,land use/land cover(LULC)changes have a profound impact on the change of ecosystem.The primary goal of this study is to determine the impacts of LULC changes on ecosystem service values(ESVs)in the upper Gilgel Abbay watershed,Ethiopia.Changes in LULC types were studied using three Landsat images representing 1986,2003,and 2021.The Landsat images were classified using a supervised image classification technique in Earth Resources Data Analysis System(ERDAS)Imagine 2014.We classified ESs in this study into four categories(including provisioning,regulating,supporting,and cultural services)based on global ES classification scheme.The adjusted ESV coefficient benefit approach was employed to measure the impacts of LULC changes on ESVs.Five LULC types were identified in this study,including cultivated land,forest,shrubland,grassland,and water body.The result revealed that the area of cultivated land accounted for 64.50%,71.50%,and 61.50%of the total area in 1986,2003,and 2021,respectively.The percentage of the total area covered by forest was 9.50%,5.90%,and 14.80%in 1986,2003,and 2021,respectively.Result revealed that the total ESV decreased from 7.42×10^(7) to 6.44×10^(7) USD between 1986 and 2003.This is due to the expansion of cultivated land at the expense of forest and shrubland.However,the total ESV increased from 6.44×10^(7) to 7.76×10^(7) USD during 2003-2021,because of the increment of forest and shrubland.The expansion of cultivated land and the reductions of forest and shrubland reduced most individual ESs during 1986-2003.Nevertheless,the increase in forest and shrubland at the expense of cultivated land enhanced many ESs during 2003-2021.Therefore,the findings suggest that appropriate land use practices should be scaled-up to sustainably maintain ESs.展开更多
In GNSS denied environments,pseudolites have to rely on prior information,such as ground anchoring points,terrain matching or other multi-source means for positioning.This paper proposes a method of dynamic networking...In GNSS denied environments,pseudolites have to rely on prior information,such as ground anchoring points,terrain matching or other multi-source means for positioning.This paper proposes a method of dynamic networking of UAVs pseudolites for accurate navigation with only inertial navigation during GNSS denied area,which can provide accurate positioning services without prior information like anchor points.On this basis,this paper proposes a mathematical model of UAV pseudolite networking to describe the relationship of UAV flight altitude,network service coverage and anti-jamming capabilities.This model demonstrates excellent anti-interference ability,which can achieve a maximum power enhancement of up to 54.58 dB.And it can also offer another operating mode with a maximum coverage range of up to 2675.47 km^(2),while still ensuring a power enhancement of 37.57dB.This method can effectively solve the problem of providing continuous positioning services as an alternative GNSS,and is also a powerful support solution for resilient Positioning,Navigation,and Timing(PNT)^([1]).展开更多
Objective Systematically integrate nurses’experience with“Internet Nursing Service”to analysis the nurses’experiences with“Internet Nursing Service”,and to provide a theoretical reference for formulating a more ...Objective Systematically integrate nurses’experience with“Internet Nursing Service”to analysis the nurses’experiences with“Internet Nursing Service”,and to provide a theoretical reference for formulating a more rational“Internet Nursing Service”model.Methods A systematic search in PubMed,Embase,Web of Science,the Cochrane Library,CINAHL,China National Knowledge Infrastructure(CNKI),Wanfang Database,and Chinese Biomedical Literature Database was conducted to collect qualitative research on nurses’experiences with“Internet Nursing Service,”with a retrieval time limit from December 2019 to June 2024.Qualitative meta-synthesis was performed through line-by-line coding of relevant quotes,organization of codes into descriptive themes,and development of analytical themes.Results A total of 19 studies were included,one study was rated as Grade A in quality evaluation,and the remaining studies were rated as Grade B.Collectively synthesized into three integrated results:Harvest and growth,Difficulties and challenges,and Expectations and support.Harvest and growth,include 1)manifestation of self-value,2)enhancing nursing capabilities,3)optimizing nursing resources;Difficulties and challenges,include 1)lack of safety guarantee,2)role conflict;Expectations and support include,1)expectation for professional knowledge and skill training,2)expectations for service platform optimization,3)expectation for reasonable charges,4)expectation for related policy support.Conclusion“Internet Nursing Service”model benefits both nurses and patients,but still full of challenges.It aids in the decentralization of medical resources.Management departments still need to encourage nurses to actively invest in“Internet Nursing Service”while ensuring their safety and interests.展开更多
The Qinghai-Xizang Plateau(QXP)serves as a crucial ecological barrier in China and Asia,exerting profound influences on global climate and biodiversity conservation.Gannan Tibetan Autonomous Prefecture(hereinafter ref...The Qinghai-Xizang Plateau(QXP)serves as a crucial ecological barrier in China and Asia,exerting profound influences on global climate and biodiversity conservation.Gannan Tibetan Autonomous Prefecture(hereinafter referred as Gannan Prefecture),located on the northeastern edge of the QXP,represents a fragile alpine ecosystem in which land use change significantly impacts ecosystem services(ESs).This study established a comprehensive framework,utilizing the Patch-generating Land-Use Simulation(PLUS)model coupled with the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model to predict land use patterns under the natural development scenario,cultivated land protection scenario,and ecological protection scenario for Gannan Prefecture by 2030 and evaluated four critical ESs:habitat quality(HQ),water yield(WY),soil retention(SR),and carbon storage(CS).The primary aim is to elucidate the impacts of dynamic land use change on ESs.The results revealed that,from 2000 to 2020,HQ exhibited minimal variation,whereas CS experienced a slight decline.Conversely,WY and SR showed significant improvements.Under the natural development scenario,construction land was projected to increase by 4247.74 hm^(2),primarily at the expense of forest land.The cultivated land protection scenario anticipated an increase in farmland by 2634.36 hm^(2),which was crucial for maintaining food security.The ecological protection scenario predicted a notable expansion of forest land,accompanied by a restrained development rate of construction land.The ecological protection scenario also showed an increase in the ecosystem service index(ESI),encompassing 26.07%of the region.Forest land and grassland emerged as the primary contributors to ESs,while construction land substantially impacted WY.Water bodies exhibited minimal contribution to ESs.This study enhanced the understanding of land use change impacts on ESs in fragile and high-altitude ecosystems,offering essential theoretical frameworks and practical direction for forthcoming ecological policy and regional planning endeavors.展开更多
Quantifying and mapping how ecosystem services impact agricultural competitiveness is crucial for attaining the Sustainable Development Goals of United Nations.However,few study quantified agricultural competitiveness...Quantifying and mapping how ecosystem services impact agricultural competitiveness is crucial for attaining the Sustainable Development Goals of United Nations.However,few study quantified agricultural competitiveness and mapped the effects of ecosystem services on agricultural competitiveness using multiple models.In this study,multi-source data from 2000 to 2020 were utilized to establish the indicator system of agricultural competitiveness;five ecosystem services were quantified using computation models;Geographic Information System(GIS)spatial analysis was used to explore the spatial patterns of agricultural competitiveness and ecosystem services;geographic detector models were applied to investigate the effects and driving mechanisms of ecosystem services on agricultural competitiveness.Shandong Province of China was selected as the case study area.The results demonstrated that:1)there was a significant increase in agricultural competitiveness during the study period,with high levels observed mainly in the east region of the study area.2)The spatial distribution patterns of ecosystem services and agricultural competitiveness primarily exhibited High-High and Low-Low Cluster types.3)Habitat quality emerged as the main driving factor of agricultural competitiveness in 2000 and 2020,while water yield played a substantial role in 2010.4)The coupling of two ecosystem services exerted a greater effect on agricultural competitiveness compared to individual ecosystem service.The innovations of this study are constructing an indicator system to quantify agricultural competitiveness,and exploring the effects of ecosystem services on agricultural competitiveness.This study proposed an indicator system to quantify agricultural competitiveness,which can be applied in other regions,and explored the effects of ecosystem services on agricultural competitiveness.The findings of this study can serve as valuable insights for policymakers to formulate tailored agricultural development policies that take into account the synergistic effects of ecosystem services on agricultural competitiveness.展开更多
With the deployment of ultra-dense low earth orbit(LEO)satellite constellations,LEO satellite access network(LEO-SAN)is envisioned to achieve global Internet coverage.Meanwhile,the civil aviation communications have i...With the deployment of ultra-dense low earth orbit(LEO)satellite constellations,LEO satellite access network(LEO-SAN)is envisioned to achieve global Internet coverage.Meanwhile,the civil aviation communications have increased dramatically,especially for providing airborne Internet services.However,due to dynamic service demands and onboard LEO resources over time and space,it poses huge challenges in satellite-aircraft access and service management in ultra-dense LEO satellite networks(UDLSN).In this paper,we propose a deep reinforcement learning-based approach for ultra-dense LEO satellite-aircraft access and service management.Firstly,we develop an airborne Internet architecture based on UDLSN and design a management mechanism including medium earth orbit satellites to guarantee lightweight management.Secondly,considering latency-sensitive and latency-tolerant services,we formulate the problem of satellite-aircraft access and service management for civil aviation to ensure service continuity.Finally,we propose a proximal policy optimization-based access and service management algorithm to solve the formulated problem.Simulation results demonstrate the convergence and effectiveness of the proposed algorithm with satisfying the service continuity when applying to the UDLSN.展开更多
文摘In order to explore the serviceability and reinforcement of CaCO3 whisker in portland cement matrix, the durability of CaCO3 whisker and effect of low whisker content（0%-4.0%） on the working performance and mechanical properties of portland cement were investigated. The experimental results show that CaCO3 whiskers have a good stability and serviceability in cement, and should not significantly alter the rheological properties of the cement paste. The flexural and compressive strength of portland cement reinforced by CaCO3 whiskers was increased by 33.3% and 12.83%, respectively.
基金National Natural Science Foundation of China under Grant No.5210082055China Postdoctoral Science Foundation under Grant No.2021M690278。
文摘The serviceability of water supply networks(WSNs)under seismic loads has significant importance for estimating the probable losses and the impact of diminished functionality on affected communities.The innovation presented in this paper is suggesting a new strategy to evaluate the seismic serviceability of WSNs,utilizing their operational physical mechanism.On one hand,this method can obtain the seismic serviceability of each node as well as entire WSNs.On the other hand,this method can dynamically reflect the propagation of randomness from ground motions to WSNs.First,a finite element model is established to capture the seismic response of buried pipe networks,and a leakage model is suggested to obtain the leakage area of WSNs.Second,the transient flow analysis of WSNs with or without leakage is derived to obtain dynamic water flow and pressure.Third,the seismic serviceability of WSNs is analyzed based on the probability density evolution method(PDEM).Finally,the seismic serviceability of a real WSN in Mianzhu city is assessed to illustrate the method.The case study shows that randomness from the ground motions can obviously affect the leakage state and the probability density of the nodal head during earthquakes.
基金National Natural Science Foundation of China Under Grant No.51178100Foundation of the Priority Sciences Development Program of Higher Education Institutions of Jiangsu Province Under Grant No.1105007001+1 种基金Teaching and Research Foundation for Excellent Young Teachers of Southeast University Under Grant No.3205001205Scientific Research Foundation the Scientific Research Foundation of Graduate School of Southeast University Under Grant No.YBJJ1006
文摘The increasing strength of new structural materials and the span of new structures, accompanied by aesthetic requirements for greater slenderness, are resulting in more applications of long-span structures. In this paper, serviceability control technology and its design theory are studied. First, a novel tuned mass damper （TMD） with controllable stiffness is developed. Second, methods for modeling human-induced loads are proposed, including standing up, walking, jumping and running, and an analysis method for long-span floor response is proposed based on a finite element model. Third, a design method for long-span floors installed with a multiple TMD （MTMD） system considering human comfort is introduced, largely based on a study of existing literature. Finally, a design, analysis and field test is conducted using several large scale buildings in China including the Beijing Olympic Park National Conference Center, Changsha New Railway Station and the Xi＇an Northern Railway Station. The analytical and field test results show that the MTMD system designed using the proposed method is capable of effectively mitigating the vertical vibration of long-span floor structures. The study presented in this paper provides an important reference for the analysis of vibration serviceability of similar long-span floors and design of control system for these structures.
基金National Natural Science Foundation of China under Grant No.51438001Fundamental Research Funds for the Central Universities under Grant Nos.106112014CDJZR200001 and 106112015CDJXZ208804+1 种基金Chongqing basic and frontier research project under Grant No.cstc2014jcyjys30001National key research and development program of China under Grant No.2016YFC0701201
文摘An extensive experimental and theoretical research study was undertaken to study the vibration serviceability of a long-span prestressed concrete floor system to be used in the lounge of a major airport.Specifically,jumping impact tests were carried out to obtain the floor’s modal parameters,followed by an analysis of the distribution of peak accelerations.Running tests were also performed to capture the acceleration responses.The prestressed concrete floor was found to have a low fundamental natural frequency（≈8.86 Hz）corresponding to the average modal damping ratio of≈2.17%.A coefficients plate with simply-supported edges.The calculated analytical results（natural frequencies and root-mean-square acceleration）agree well with the experimental ones.The analytical approach is thus validated.
文摘The reliability and deterministic analyses of wood-cored stiffened deep cement mixing and deep cement mixing column-supported embankments(referred to as WSCSE and DCSE,respectively)considering serviceability limit state requirements are presented in this paper.Random field theory was used to simulate the spatial variability of soilcement mixing(SCM)material in which the adaptive Kriging Monte Carlo simulation was adopted to estimate the failure probability of a columnsupported embankment(CSE)system.A new method for stochastically generating random values of unconfined compressive strength(qu)and the ratio(Ru)between the undrained elastic modulus and qu of SCM material based on statistical correlation data is proposed.Reliability performance of CSEs concerning changes in the mean(μ),coefficient of variation(CoV),and vertical spatial correlation length(θv)of qu and Ru are presented and discussed.The obtained results indicate that WSCSE can provide a significantly higher reliability level and can tolerate more SCM material spatial variability than DCSE.Some performance of DCSE and WSCSE,which can be considered satisfactory in a deterministic framework,cannot guarantee an acceptable reliability level from a probabilistic viewpoint.This highlights the importance and necessity of employing reliability analyses for the design of CSEs.Moreover,consideration of only μ and CoV of qu seems to be sufficient for reliability analysis of WSCSE while for DCSE,uncertainties regarding the Ru(i.e.both μ and CoV)and θv of qu cannot be ignored.
基金Projects(51278216,51308241)supported by the National Natural Science Foundation of ChinaProject(2013BS010)supported by the Funds of Henan University of Technology for High-level Talents,China
文摘The objective is to develop an approach for the determination of the target reliability index for serviceability limit state(SLS) of single piles. This contributes to conducting the SLS reliability-based design(RBD) of piles. Based on a two-parameter,hyperbolic curve-fitting equation describing the load-settlement relation of piles, the SLS model factor is defined. Then, taking into account the uncertainties of load-settlement model, load and bearing capacity of piles, the formula for computing the SLS reliability index(βsls) is obtained using the mean value first order second moment(MVFOSM) method. Meanwhile, the limit state function for conducting the SLS reliability analysis by the Monte Carlo simulation(MCS) method is established. These two methods are finally applied to determine the SLS target reliability index. Herein, the limiting tolerable settlement(slt) is treated as a random variable. For illustration, four load test databases from South Africa are compiled again to conduct reliability analysis and present the recommended target reliability indices. The results indicate that the MVFOSM method overestimates βsls compared to that computed by the MCS method. Besides, both factor of safety(FS) and slt are key factors influencing βsls, so the combination of FS and βsls is welcome to be used for the SLS reliability analysis of piles when slt is determined. For smaller slt, pile types and soils conditions have significant influence on the SLS target reliability indices; for larger slt, slt is the major factor having influence on the SLS target reliability indices. This proves that slt is the most key parameter for the determination of the SLS target reliability index.
基金Supported by Education Department of Heilongjiang Province (9551022)
文摘For further understanding reliability and serviceability of tractor and to furnish scientific and technical theories, based on the promotion and application of it, the following experiments and statistical analysis on reliability （reliability and MTBF） serviceability （service and MTTR） of Donfanghong-1002 and Dongfanghong-802 were conducted. The result showed that the intervals of average troubles of these two tractors were 182.62 h and 160.2 h, respectively, and the weakest assembly of them was engine part.
基金This work was supported by Natural Science Foundation of Gansu Province of China(20JR10RA625,20JR10RA623)National Key Research and Development Project of China(Project No.2019YFC1511005)+1 种基金Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2020-55)National Natural Science Foundation of China(Grant No.51608243).
文摘This article presented a new data fusion approach for reasonably predicting dynamic serviceability reliability of the long-span bridge girder.Firstly,multivariate Bayesian dynamic linear model(MBDLM)considering dynamic correlation among the multiple variables is provided to predict dynamic extreme deflections;secondly,with the proposed MBDLM,the dynamic correlation coefficients between any two performance functions can be predicted;finally,based on MBDLM and Gaussian copula technique,a new data fusion method is given to predict the serviceability reliability of the long-span bridge girder,and the monitoring extreme deflection data from an actual bridge is provided to illustrated the feasibility and application of the proposed method.
文摘This paper provides innovative and effective instruments for the simplified analysis of serviceability limit states for pitched, kinked, and tapered GLT beams. Specifically, formulas for the evaluation of maximal horizontal and vertical displacements are derived from a recently-proposed Timoshenko-like non-prismatic beam model. Thereafter, the paper compares the proposed serviceability analysis formulas with other ones available in literature and with highly-refined 2D FE simulations in order to demonstrate the effectiveness of the proposed instruments. The proposed formulas lead to estimations that lie mainly on the conservative side and the errors are smaller than 10% (exceptionally up to 15%) in almost all of the cases of interest for practitioners. Conversely, the accuracy of the proposed formulas decreases for thick and highly-tapered beams since the beam model behind the proposed formulas cannot tackle local effects (like stress concentrations occurring at bearing and beam apex) that significantly influence the beam behavior for such geometries. Finally, the proposed formulas are more accurate than the ones available in literature since the latter ones often provide non-conservative estimations and errors greater than 20% (up to 120%).
文摘In Indian mixed traffic, a common scenario is when motorized vehicles, non-motorized vehicles including pedestrians use the same road space. In such conditions, ifPLOS （pedestrian level of service） is measured using conventional methods, i.e., considering pedestrians walking on footpath only; leads to unrealistic results as most of the time pedestrians are seen walking on the path dedicated for vehicles, i.e., vehicle-path. The decision making behavior of pedestrians regarding walking on footpath or on vehicle-path is influenced by the quality of footpath as well as the characteristics of traffic on vehicle-path and the presence of vendors in the street. Hardly any research carried out on measuring pedestrians＇ serviceability on road considering pedestrians walking on vehicle-path. This study attempts to estimate the effect of various parameters such as intensity of vehicular traffic on the vehicle-path, presence of street vendors on the vehicle-path, etc., on pedestrians＇ decision of walking on footpath or on vehicle-path based on data collected at two locations in New Delhi, India, by using various statistical methods, especially binary logistic regression. One of the locations is an urban two-lane undivided road with footpath on both sides, a part of National Highway-2, another one is a four-lane divided road with footpath on both sides which is a typical arterial road. It has been found that vendors play a significant role in pedestrians＇ decision making regarding walking on footpath or on vehicle-path. Study proposes a model to measure pedestrians＇ serviceability on a road where pedestrians may be walking on the vehicle-path even in the presence of footpath.
基金the National Science Fund for Distinguished Young Scholars (No. 50225825)
文摘This paper presents a simplified beam design method for semi-rigid composite frames with vertical loading at the serviceability limit state. Equations were developed to determine the deflections of the composite beam allowing for both joint flexibility and beam sectional properties, along with a formula for the connection secant stiffness. The equations for the connection stiffness are more accurate than previous equations used because it considers the beam-to-column stiffness ratio and the beam-to-connection stiffness ratio. The equations were validated by the experimental results for two semi-rigid composite frames. The equations agree well with the experimental data because they take into account the actual beam-to-column connections and the composite action between the steel beam and the concrete slab.
文摘Common mental disorders(CMDs),such as depressive and anxiety disorders,constitute a significant public health problem in low-and middle-income countries,such as India,where they rank among the leading causes of disability and impaired quality of life.Outcomes are further compromised by a large treatment gap,poor adherence to therapeutic regimens,and high attrition rates.The prevalence and severity of CMDs are disproportionately higher in women.Additionally,structural factors influencing healthcare access,along with sociocultural factors,such as gender-based violence,limited autonomy in healthcare decisions,and greater levels of discrimination and stigma,result in poorer outcomes among women with CMDs.Therefore,there is a pressing need for care packages that are culturally sensitive,gender-responsive,and designed to address these structural and sociocultural factors,as highlighted in the literature from India.
文摘In Wuhu,urban renewal has not only transformed the development process,but improved people’s lives.DURING the 14th Five-Year Plan period(2021-2025),urban renewal has served as a crucial measure to promote high-quality urban development and continuously meet people’s growing aspirations for a better life.Wuhu,in central China’s Anhui Province,has consistently enhanced its urban functions and services to build a modern,people-oriented city that is innovative,livable,beautiful,resilient,and smart.
基金supported by the Key Program of the National Natural Science Foundation of China(Grant No.41931293)the National Natural Science Foundation of China(Grant No.42271275).
文摘The rapid population and land urbanization not only promoted economic development but also affected the ecosystem service value(ESV).In the context of new-type urbanization and green development,it’s essential to investigate the impacts of urbanization on ESV in China.However,a comprehensive and dynamic framework to reveal the relationship between ESV and urbanization processes is lacking.This study adopted multi-source datasets to portray China’s urbanization process by integrating population,land,and economic urbanization,eval-uated the ESV changes of 10 categories by gross ecosystem product(GEP)methods,and explored ESV changes within different urbanization scales and speeds.The results showed rapid urbanization in the population,land,and economic dimensions in China,with a faster process of economic urbanization.The ESV also exhibited an increasing trend,with higher levels in the southeastern coastal regions and lower levels in the northwestern regions.Urbanization had positive impacts on ESV across various research units,but the ESV exhibited heteroge-neous changes across different urbanization scales,speeds,and their interactive effects.The response of ESV to dynamic urbanization processes was influenced by socio-economic,ecological,and policy factors;it is essential to combine targeted measures with general ecological product value realization methods in each unit to maximize social-economic-ecological benefits.
文摘Human well-being and livelihoods depend on natural ecosystem services(ESs).Following the increment of population,ESs have been deteriorated over time.Ultimately,land use/land cover(LULC)changes have a profound impact on the change of ecosystem.The primary goal of this study is to determine the impacts of LULC changes on ecosystem service values(ESVs)in the upper Gilgel Abbay watershed,Ethiopia.Changes in LULC types were studied using three Landsat images representing 1986,2003,and 2021.The Landsat images were classified using a supervised image classification technique in Earth Resources Data Analysis System(ERDAS)Imagine 2014.We classified ESs in this study into four categories(including provisioning,regulating,supporting,and cultural services)based on global ES classification scheme.The adjusted ESV coefficient benefit approach was employed to measure the impacts of LULC changes on ESVs.Five LULC types were identified in this study,including cultivated land,forest,shrubland,grassland,and water body.The result revealed that the area of cultivated land accounted for 64.50%,71.50%,and 61.50%of the total area in 1986,2003,and 2021,respectively.The percentage of the total area covered by forest was 9.50%,5.90%,and 14.80%in 1986,2003,and 2021,respectively.Result revealed that the total ESV decreased from 7.42×10^(7) to 6.44×10^(7) USD between 1986 and 2003.This is due to the expansion of cultivated land at the expense of forest and shrubland.However,the total ESV increased from 6.44×10^(7) to 7.76×10^(7) USD during 2003-2021,because of the increment of forest and shrubland.The expansion of cultivated land and the reductions of forest and shrubland reduced most individual ESs during 1986-2003.Nevertheless,the increase in forest and shrubland at the expense of cultivated land enhanced many ESs during 2003-2021.Therefore,the findings suggest that appropriate land use practices should be scaled-up to sustainably maintain ESs.
基金National Social Science Fund of China(No.2023-SKJJ-B-069).
文摘In GNSS denied environments,pseudolites have to rely on prior information,such as ground anchoring points,terrain matching or other multi-source means for positioning.This paper proposes a method of dynamic networking of UAVs pseudolites for accurate navigation with only inertial navigation during GNSS denied area,which can provide accurate positioning services without prior information like anchor points.On this basis,this paper proposes a mathematical model of UAV pseudolite networking to describe the relationship of UAV flight altitude,network service coverage and anti-jamming capabilities.This model demonstrates excellent anti-interference ability,which can achieve a maximum power enhancement of up to 54.58 dB.And it can also offer another operating mode with a maximum coverage range of up to 2675.47 km^(2),while still ensuring a power enhancement of 37.57dB.This method can effectively solve the problem of providing continuous positioning services as an alternative GNSS,and is also a powerful support solution for resilient Positioning,Navigation,and Timing(PNT)^([1]).
基金supported by the General Project of the Cultivation Project of the Chinese Hospital Reform and Development Research Institute of Nanjing University(NDYG2022072)。
文摘Objective Systematically integrate nurses’experience with“Internet Nursing Service”to analysis the nurses’experiences with“Internet Nursing Service”,and to provide a theoretical reference for formulating a more rational“Internet Nursing Service”model.Methods A systematic search in PubMed,Embase,Web of Science,the Cochrane Library,CINAHL,China National Knowledge Infrastructure(CNKI),Wanfang Database,and Chinese Biomedical Literature Database was conducted to collect qualitative research on nurses’experiences with“Internet Nursing Service,”with a retrieval time limit from December 2019 to June 2024.Qualitative meta-synthesis was performed through line-by-line coding of relevant quotes,organization of codes into descriptive themes,and development of analytical themes.Results A total of 19 studies were included,one study was rated as Grade A in quality evaluation,and the remaining studies were rated as Grade B.Collectively synthesized into three integrated results:Harvest and growth,Difficulties and challenges,and Expectations and support.Harvest and growth,include 1)manifestation of self-value,2)enhancing nursing capabilities,3)optimizing nursing resources;Difficulties and challenges,include 1)lack of safety guarantee,2)role conflict;Expectations and support include,1)expectation for professional knowledge and skill training,2)expectations for service platform optimization,3)expectation for reasonable charges,4)expectation for related policy support.Conclusion“Internet Nursing Service”model benefits both nurses and patients,but still full of challenges.It aids in the decentralization of medical resources.Management departments still need to encourage nurses to actively invest in“Internet Nursing Service”while ensuring their safety and interests.
基金funded by the National Natural Science Foundation of China(42101276)the Major Project of Key Research Bases for Humanities and Social Sciences Funded by the Ministry of Education of China(22JJD790015)the Science and Technology Project of Gansu Province,China(20JR5RA529).
文摘The Qinghai-Xizang Plateau(QXP)serves as a crucial ecological barrier in China and Asia,exerting profound influences on global climate and biodiversity conservation.Gannan Tibetan Autonomous Prefecture(hereinafter referred as Gannan Prefecture),located on the northeastern edge of the QXP,represents a fragile alpine ecosystem in which land use change significantly impacts ecosystem services(ESs).This study established a comprehensive framework,utilizing the Patch-generating Land-Use Simulation(PLUS)model coupled with the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model to predict land use patterns under the natural development scenario,cultivated land protection scenario,and ecological protection scenario for Gannan Prefecture by 2030 and evaluated four critical ESs:habitat quality(HQ),water yield(WY),soil retention(SR),and carbon storage(CS).The primary aim is to elucidate the impacts of dynamic land use change on ESs.The results revealed that,from 2000 to 2020,HQ exhibited minimal variation,whereas CS experienced a slight decline.Conversely,WY and SR showed significant improvements.Under the natural development scenario,construction land was projected to increase by 4247.74 hm^(2),primarily at the expense of forest land.The cultivated land protection scenario anticipated an increase in farmland by 2634.36 hm^(2),which was crucial for maintaining food security.The ecological protection scenario predicted a notable expansion of forest land,accompanied by a restrained development rate of construction land.The ecological protection scenario also showed an increase in the ecosystem service index(ESI),encompassing 26.07%of the region.Forest land and grassland emerged as the primary contributors to ESs,while construction land substantially impacted WY.Water bodies exhibited minimal contribution to ESs.This study enhanced the understanding of land use change impacts on ESs in fragile and high-altitude ecosystems,offering essential theoretical frameworks and practical direction for forthcoming ecological policy and regional planning endeavors.
基金Under the auspices of the National Key Research and Development Program of China(No.2022YFC3204404)。
文摘Quantifying and mapping how ecosystem services impact agricultural competitiveness is crucial for attaining the Sustainable Development Goals of United Nations.However,few study quantified agricultural competitiveness and mapped the effects of ecosystem services on agricultural competitiveness using multiple models.In this study,multi-source data from 2000 to 2020 were utilized to establish the indicator system of agricultural competitiveness;five ecosystem services were quantified using computation models;Geographic Information System(GIS)spatial analysis was used to explore the spatial patterns of agricultural competitiveness and ecosystem services;geographic detector models were applied to investigate the effects and driving mechanisms of ecosystem services on agricultural competitiveness.Shandong Province of China was selected as the case study area.The results demonstrated that:1)there was a significant increase in agricultural competitiveness during the study period,with high levels observed mainly in the east region of the study area.2)The spatial distribution patterns of ecosystem services and agricultural competitiveness primarily exhibited High-High and Low-Low Cluster types.3)Habitat quality emerged as the main driving factor of agricultural competitiveness in 2000 and 2020,while water yield played a substantial role in 2010.4)The coupling of two ecosystem services exerted a greater effect on agricultural competitiveness compared to individual ecosystem service.The innovations of this study are constructing an indicator system to quantify agricultural competitiveness,and exploring the effects of ecosystem services on agricultural competitiveness.This study proposed an indicator system to quantify agricultural competitiveness,which can be applied in other regions,and explored the effects of ecosystem services on agricultural competitiveness.The findings of this study can serve as valuable insights for policymakers to formulate tailored agricultural development policies that take into account the synergistic effects of ecosystem services on agricultural competitiveness.
基金supported in part by the National Key R&D Program of China under Grant 2020YFB1806104in part by Innovation and Entrepreneurship of Jiangsu Province High-level Talent Program+1 种基金in part by Natural Sciences and Engineering Research Council of Canada (NSERC)the support from Huawei
文摘With the deployment of ultra-dense low earth orbit(LEO)satellite constellations,LEO satellite access network(LEO-SAN)is envisioned to achieve global Internet coverage.Meanwhile,the civil aviation communications have increased dramatically,especially for providing airborne Internet services.However,due to dynamic service demands and onboard LEO resources over time and space,it poses huge challenges in satellite-aircraft access and service management in ultra-dense LEO satellite networks(UDLSN).In this paper,we propose a deep reinforcement learning-based approach for ultra-dense LEO satellite-aircraft access and service management.Firstly,we develop an airborne Internet architecture based on UDLSN and design a management mechanism including medium earth orbit satellites to guarantee lightweight management.Secondly,considering latency-sensitive and latency-tolerant services,we formulate the problem of satellite-aircraft access and service management for civil aviation to ensure service continuity.Finally,we propose a proximal policy optimization-based access and service management algorithm to solve the formulated problem.Simulation results demonstrate the convergence and effectiveness of the proposed algorithm with satisfying the service continuity when applying to the UDLSN.
