Atmospheric nitrogen(N)deposition has experienced significant change because of anthropogenic emissions,thereby exerting a pronounced impact on global ecosystem services.With the rapid development of industry and agri...Atmospheric nitrogen(N)deposition has experienced significant change because of anthropogenic emissions,thereby exerting a pronounced impact on global ecosystem services.With the rapid development of industry and agriculture and the swift expansion of urban areas in China since the 1980s,reactive nitrogen(Nr)emissions and N deposition have substantially increased.In pursuit of im-proving air quality,China has implemented a series of environmental protection policies and undertaken diverse measures to reduce pol-lutant emissions.This paper is a review of multivariate data sources of atmospheric N deposition based on the results of literature from 1980 to 2023,and the original data from 1980 to 2020 are summarized,counted and calculated.The main findings are as follows:1)the annual average atmospheric N deposition ranged from approximately 20-40 kg/(ha·yr),with the variability primarily linked to different assessment methods;2)regional disparities were evident in the spatial distribution of N deposition,with elevated values concentrated in areas with intense Nr emissions;3)atmospheric N deposition significantly declined after 2010,particularly the deposition of oxidized N,while reduced N deposition remained stable.These results reflect the effects of China's serious control policies on nitrogen oxide(NO.)emissions and strengthen the importance of agricultural NH3 emission mitigation.This study contributes to a comprehensive understanding of the N dynamics in the emission-deposition process,and provides a scientific foundation for the research of environmental protection,climate change,and sustainable development.展开更多
Based on the number of customers and the server’s workload,this paper proposes a modified Min(N,D)-policy and discusses an M/G/1 queueing model with delayed randomized multiple vacations under such a policy.Applying ...Based on the number of customers and the server’s workload,this paper proposes a modified Min(N,D)-policy and discusses an M/G/1 queueing model with delayed randomized multiple vacations under such a policy.Applying the well-known stochastic decomposition property of the steady-state queue size,the probability generating function of the steady-state queue length distribution is obtained.Moreover,the explicit expressions of the expected queue length and the additional queue length distribution are derived by some algebraic manipulations.Finally,employing the renewal reward theorem,the explicit expression of the long-run expected cost per unit time is given.Furthermore,we analyze the optimal policy for economizing the expected cost and compare the optimal Min(N,D)-policy with the optimal N-policy and the optimal D-policy by using numerical examples.展开更多
To develop a sound ozone（O_3） pollution control strategy,it is important to well understand and characterize the source contribution due to the complex chemical and physical formation processes of O_3.Using the ＂Sh...To develop a sound ozone（O_3） pollution control strategy,it is important to well understand and characterize the source contribution due to the complex chemical and physical formation processes of O_3.Using the ＂Shunde＂ city as a pilot summer case study,we apply an innovative response surface modeling（RSM） methodology based on the Community Multi-Scale Air Quality（CMAQ） modeling simulations to identify the O_3 regime and provide dynamic analysis of the precursor contributions to effectively assess the O_3 impacts of volatile organic compound（VOC） control strategy.Our results show that Shunde is a typical VOC-limited urban O_3 polluted city.The ＂Jiangmen＂ city,as the main upper wind area during July 2014,its VOCs and nitrogen oxides（NO_x） emissions make up the largest contribution（9.06%）.On the contrary,the contribution from local（Shunde） emission is lowest（6.35%） among the seven neighbor regions.The local VOCs industrial source emission has the largest contribution comparing to other precursor emission sectors in Shunde.The results of dynamic source contribution analysis further show that the local NO_x control could slightly increase the ground O_3 under low（10.00%） and medium（40.00%）reduction ratios,while it could start to turn positive to decrease ground O_3 under the high NO_x abatement ratio（75.00%）.The real-time assessment of O_3 impacts from VOCs control strategies in Pearl River Delta（PRD） shows that the joint regional VOCs emission control policy will effectively reduce the ground O_3 concentration in Shunde.展开更多
Loess Plateau is the most serious region of soil and water loss in China and the world. The sediment carried into the Yellow River amounts to 1.6 billion tons every year. This paper reviews the factors and reasons for...Loess Plateau is the most serious region of soil and water loss in China and the world. The sediment carried into the Yellow River amounts to 1.6 billion tons every year. This paper reviews the factors and reasons for erosion in this area, and puts forward a comprehensive controlling policy on the basis of the principles of ecology and practise of Chinese scientists for 40 years. In conformity with the policy, a number of technical measures for controlling soil and water loss are suggested.展开更多
Clean air is fundamental to human health.Approximately 99%of the global population has been exposed to concentrations higher than the World Health Organization’s recommendations.Moreover,adverse health effects have b...Clean air is fundamental to human health.Approximately 99%of the global population has been exposed to concentrations higher than the World Health Organization’s recommendations.Moreover,adverse health effects have been observed at much lower pollution levels than previously studied.China has experienced periods of severe air pollution over the past few decades.To improve air quality and safeguard public health,the government has implemented several progressively tightened policies.Emission control policies were first proposed in 2005.展开更多
Achieving robust walking for different stairs is one of the most challenging tasks for quadruped robots in real world.Traditional model-based methods heavily rely on environmental factors,are burdened by intricate mod...Achieving robust walking for different stairs is one of the most challenging tasks for quadruped robots in real world.Traditional model-based methods heavily rely on environmental factors,are burdened by intricate modelling complexities,and lack generalizability.The potential for advancements in adaptive locomotion control,often impeded by complex modelling processes,can be substantially enhanced through the application of Reinforcement Learning(RL).In this paper,a learning-based method is proposed to directionally enhance the stair-climbing skill of quadruped robots under different stair conditions.First,the general policy model based on proprioceptive perception is trained as a pre-training model.Then,the pre-training model was initialized,and different terrain information from the stairs was introduced for customized training to enhance the stair-climbing skill without affecting the existing locomotion performance.Finally,the customized control policy is deployed to the real robot to realize motion control in real environments.The experimental results demonstrate that the customized control policy can significantly improve the motion performance of quadruped robots when facing complex stair terrains and has certain generalizability in other complex terrains.The proposed algorithm can be extended to various terrestrial environments.展开更多
China has put great efforts into air pollution control over the past years and recently committed to its most ambitious climate target.Cost and benefit analysis has been widely used to evaluate the control policies in...China has put great efforts into air pollution control over the past years and recently committed to its most ambitious climate target.Cost and benefit analysis has been widely used to evaluate the control policies in terms of past performance,future reduction potential,and direct and indirect impacts.To understand the cost and benefit analysis for air pollution control in China,we conducted a bibliometric review of more than 100 studies published over the past two decades,including the current research progress,most commonly adopted methods,and core findings.The control target in cost and benefit analysis has shifted in three stages,from individual and primary pollution control,moving to joint prevention of multiple and secondary pollutants,and then towards synergistic control of air pollution and carbon.With the expansion of the research scope,the integrated assessment model has gradually demonstrated the necessity for long-term ex-anti policy simulation,especially for dealing with complex factors.To ensure long-term air quality,climate,public health,and sustainable economic development,substantial evidence from published studies has suggested that China needs to continue its efforts in the upstream adjustment of the energy system and industrial structure with multi-regional and-sector collaboration.This cost and benefit review paper provides decision-makers with the fundamental information and knowledge gaps in air pollution control strategies in China,and direction for facing future challenges.展开更多
China’s emission control for nonroad diesel mobile machinery(NDMM)must deal with a fast increase in stock as well as regulations that are two decades behind those for on-road vehicles.This study provides the first la...China’s emission control for nonroad diesel mobile machinery(NDMM)must deal with a fast increase in stock as well as regulations that are two decades behind those for on-road vehicles.This study provides the first large-scale review and evaluation of China’s NDMM policies,along with emission measurements and an investigation on diesel fuel quality.The sulfur contents of the investigated diesel declined from 430 ppm(median value)in 2011 to6-8 ppm during the 2017-2018 period.The emission control of NO_(x)and PM greatly improved with the shift from the China II to China IV standards,as demonstrated by engine tests and field NO_(x)measurements.However,the NO_(x)emission factors for non-type-approved engines were approximately twice the limits of the China II standards.Emission compliance based on bench tests was not sufficient to control actual emissions because the field-measured NO_(x)emission factors of all machinery ranged from 24%to 225%greater than the respective emission limits for the engines.These circumstances adversely affected the effectiveness of the regulations and policies for China’s emission control of NDMM.Nevertheless,the policies on new and in-use NDMM,as well as diesel fuel quality,prevented NO_(x)and PM emissions amounting to 4.4 Tg and 297.8 Gg during the period 2008-2017,respectively.The emission management strategy contributed to enhancing the international competitiveness of China’s NDMM industries by promoting advanced technologies.For effective NDMM emission control in the future,portable testing and noncontact remote supervision should be strengthened;also,the issue of noncompliant diesel should be addressed through rigorous control measures and financial penalties.展开更多
This article describes the development and implementations of a novel software platform that supports real-time, science-based policy making on air quality through a user-friendly interface. The software, RSM-VAT, use...This article describes the development and implementations of a novel software platform that supports real-time, science-based policy making on air quality through a user-friendly interface. The software, RSM-VAT, uses a response surface modeling（RSM） methodology and serves as a visualization and analysis tool（VAT） for three-dimensional air quality data obtained by atmospheric models. The software features a number of powerful and intuitive data visualization functions for illustrating the complex nonlinear relationship between emission reductions and air quality benefits. The case study of contiguous U.S.demonstrates that the enhanced RSM-VAT is capable of reproducing the air quality model results with Normalized Mean Bias 〈 2% and assisting in air quality policy making in near real time.展开更多
With the rapid development of economy and motorization, the traffic congestion and environmental problems have become more and more serious day by day in Beijing. Therefore, traffic control policies have been graduall...With the rapid development of economy and motorization, the traffic congestion and environmental problems have become more and more serious day by day in Beijing. Therefore, traffic control policies have been gradually adopted by Beijing municipal government since 2008, so as to ease traffic and environmental problems. In this paper, the background and current situation of Beijing to implement traffic control policies are introduced, and also this measure is analyzed and evaluated from traffic effect, environmental effect, motor vehicle development, urban road development, public transport development, and balance between supply and demand, etc. Finally, related conclusions are drawn up as follows： an induced traffic volume will be generated by traffic control policies, and the effect of the traffic control will be erased by the natural growth rate of motor vehicles in three years; public traffic service should be improved for better making traffic control policies; the traffic congestion and environmental problems are alleviated by traffic control policies in the short term, but can＇t be fundamentally solved in the long run; traffic control policies should cooperate with other traffic demand management policies for reducing demands, and traffic condition should be optimized in both time and space, so that the traffic congestion and environmental problems will be fundamentally solved.展开更多
With the rapid development of economic activities in cities and construction industry in our country, the number of construction projects has been increasing. At the same time, this has promoted the development of lan...With the rapid development of economic activities in cities and construction industry in our country, the number of construction projects has been increasing. At the same time, this has promoted the development of land surveying and mapping work in our country to a certain extent. Land surveying and mapping is a complicated and arduous systematic work in our country, which mainly includes the surveying and mapping of planning and construction land, daily land surveying and mapping and various cadastral map data surveying and mapping systems. As the basic work of construction engineering, the quality of land surveying and mapping directly affects the overall progress of construction. Based on this, this paper analyzes the factors affecting the quality of land surveying and mapping and the control measures.展开更多
To enhance the practicability of the trust negotiation system, an agent based automated trust negotiation model （ABAM） is proposed. The ABAM introduces an agent to keep the negotiation process with no human interven...To enhance the practicability of the trust negotiation system, an agent based automated trust negotiation model （ABAM） is proposed. The ABAM introduces an agent to keep the negotiation process with no human intervention. Meanwhile, the ABAM specifies the format of a meta access control policy, and adopts credentials with flexible format to meet the requirements of access control policies instead of disclosing the whole contents of a certificate. Furthermore, the ABAM uses asymmetric functions with a high security intensity to encrypt the transmitting message, which can prevent information from being attacked. Finally, the ABAM presents a new negotiation protocol to guide the negotiation process. A use case is studied to illuminate that the ABAM is sound and reasonable. Compared with the existing work, the intelligence, privacy and negotiation efficiency are improved in the ABAM.展开更多
In recent years,great efforts have been devoted to reducing emissions from mobile sources with the dramatic growth of motor vehicle and nonroad mobile source populations.Compilation of a mobile source emission invento...In recent years,great efforts have been devoted to reducing emissions from mobile sources with the dramatic growth of motor vehicle and nonroad mobile source populations.Compilation of a mobile source emission inventory is conducive to the analysis of pollution emission characteristics and the formulation of emission reduction policies.This study summarizes the latest compilation approaches and data acquisition methods for mobile source emission inventories.For motor vehicles,a high-resolution emission inventory can be developed based on a bottom-up approach with a refined traffic flow model and real-world speed-coupled emission factors.The top-down approach has advantages when dealing with macroscale vehicle emission estimation without substantial traffic flow infrastructure.For nonroad mobile sources,nonroad machinery,inland river ships,locomotives,and civil aviation aircraft,a top-down approach based on fuel consumption or power is adopted.For ocean-going ships,a bottom-up approach based on automatic identification system(AIS)data is adopted.Three typical cases are studied,including emission reduction potential,a cost-benefit model,and marine shipping emission control.Outlooks and suggestions are given on future research directions for emission inventories for mobile sources:building localized emission models and factor databases,improving the dynamic updating capability of emission inventories,establishing a database of emission factors of unconventional pollutants and greenhouse gas from mobile sources,and establishing an urban high temporalspatial resolution volatile organic compound(VOC)evaporation emission inventory.展开更多
The proliferation of streaming service system in various application areas gains increasing importance and also poses more challenges in the research of streaming service system. In this paper, we propose a novel dyna...The proliferation of streaming service system in various application areas gains increasing importance and also poses more challenges in the research of streaming service system. In this paper, we propose a novel dynamic model composed of a set of differential equations to describe the evolution of streaming service systems. And in the model, we focus on how the policies for admission control and peer selection influence on the system. We first introduce a flexible abstraction of streaming service systems. The abstraction is generally enough to capture the essences of streaming service systems with different structures, physical characteristics,software protocols and client behaviors. Then, by analyzing the state which is defined as the number of requests, a novel dynamic model is developed in microscopic scale to characterize the behaviors of streaming service systems. The model proposed in this paper demonstrates the interactions between clients and servers and also between different servers. The interactions are primarily influenced by the admission control policy and peer selection policy. Finally, some experiments are designed to verify the validation and reasonability of the model.展开更多
As fresh agricultural products are perishable and vulnerable,reducing inventory cost is a strategic target for supply chain enterprises.How to design a reliable multi-echelon inventory control policy is still a great ...As fresh agricultural products are perishable and vulnerable,reducing inventory cost is a strategic target for supply chain enterprises.How to design a reliable multi-echelon inventory control policy is still a great challenge.Therefore,the inventory cost of a three-level fresh agricultural products inventory system was firstly mathematically analyzed.Then,the simulation-based optimization model of the multi-echelon inventory system for fresh agricultural products was proposed by using the Flexsim simulation software and the improved particle swarm optimization algorithm.Finally,the multi-echelon inventory system is simulated based on a large number of survey data.Simulation results demonstrate that the proposed simulation-based optimization model of multi-echelon inventory system for fresh agricultural products can provide decision-making and technical support for the formulation of inventory control policy,and also it shows that the modeling of system simulation is an effective method to solve the problem of complex system.展开更多
Sulfur dioxide(SO_(2))is a typical pollutant that affects human health,climate,and environmental and ecological conditions.China has been experiencing high concentrations of SO_(2),particularly in urban areas,since th...Sulfur dioxide(SO_(2))is a typical pollutant that affects human health,climate,and environmental and ecological conditions.China has been experiencing high concentrations of SO_(2),particularly in urban areas,since the 1990s.In 2010,a"joint prevention and control"(JPC)policy was issued to address air pollution problems and strengthen the regulation of SO_(2)emissions.This study aimed to describe the mitigation effects of this policy on SO_(2)emissions in 116 Chinese cities from 2003 to 2017.We applied global and local Moran's I indices to confirm the presence of significant spatial autocorrelation in SO_(2)emissions and constructed four spatial models to assess the effect of the JPC policy in reducing SO_(2)emissions and its transmission mechanism.We found that the policy decreased SO_(2)emissions by 1.89×10^(4)tons,S0_(2)intensity by 1.70 tons per km^(2),and S0_(2)per capita of 158.49 tons per 10,000 people in each city,on average,all of which are significant changes.The empirical results also show that population growth,economic structure,and environmental protection significantly decrease SO_(2)emissions.Finally,we recommended policies to encourage regional cooperation under the JPC policy,with the aim of promoting furtherreductions in SO_(2)emissions.展开更多
Empirical research on the effect of family size on child education is complicated by the endogeneity of family size. This study exploits plausibly exogenous changes in family size caused by China＇s population control...Empirical research on the effect of family size on child education is complicated by the endogeneity of family size. This study exploits plausibly exogenous changes in family size caused by China＇s population control policy to estimate the causal relationship between family size and child education outcomes. The results show that, compared to an only child, a person with an additional sibling will have an approximate seventeen percentage points lower likelihood of completing middle school in China. Separate regressions across individual characteristics reveal that much of this negative effect appears to be driven by the cohorts born in earlier years after the policy, and children with the highest birth order within a family.展开更多
Epidemiological studies have shown that infection with the human immunodeficiency virus(HIV) is an influential risk factor for infection with Mycobacterium tuberculosis(MTb),the rapid progression of the initial infect...Epidemiological studies have shown that infection with the human immunodeficiency virus(HIV) is an influential risk factor for infection with Mycobacterium tuberculosis(MTb),the rapid progression of the initial infection to active tuberculosis(TB),and the reactivation of latent TB infection.MTb infection is also one of the most common opportunistic infections in people with HIV,including AIDS patients receiving anti-retroviral therapy.Given the prevalence of HIV infection,the incidence of TB infection,which had begun to decline,is facing a severe situation.HIV associated with TB exerts an immense burden on the public health-care system,especially in countries with high incidences of HIV infection.Therefore,the global policies for the prevention and control of TB should be revised.Moreover,an increased investment in TB control has to be guaranteed.The purpose of this review is to summarize the recent progress in the prevention,treatment,and control of HIV and TB co-infection.展开更多
This paper investigates a multi-component repairable system with double threshold control policy.The system is composed of n identical and independent components which operate simultaneously at the beginning,and it is...This paper investigates a multi-component repairable system with double threshold control policy.The system is composed of n identical and independent components which operate simultaneously at the beginning,and it is down when the number of operating components decreases to k−1(k≤n).When the number of failed components is less than the value L,the repairman repairs them with a low repair rate.The high repair rate is activated as soon as L failed components present,and continues until the number of failed components drops to the value N−1.Applying the matrix analytical method,the Laplace transform technique and the properties of the phase type distribution,various performance measures including the availability,the rate of occurrence of failures,and the reliability are derived in transient and stationary regimes.Further,numerical examples are reported to show the behaviour of the system.展开更多
The Inter-Parliamentary Union was formed in 1889, gathering, initially, 38 British and French parliamentarians. The IPU （guided, from 1901 up to 1908, by Fredreric Passy and William Randall Cremer）, was to support a...The Inter-Parliamentary Union was formed in 1889, gathering, initially, 38 British and French parliamentarians. The IPU （guided, from 1901 up to 1908, by Fredreric Passy and William Randall Cremer）, was to support and reinforce the objective of extending arbitration as a ＇peaceful tool＇ for resolving the dispute between states. The aftermath of the First World War marked a decisive step forward in the development of a strong liberal internationalist milieux which promoted a peaceful order based on the international rule of law. This paper summarizes some issues of ongoing research and it focuses on two key topics： the rise of parliamentary control of foreign policy and the making of ＇parliamentary diplomacy＇. Besides, it tried to elucidate, from another point of view, the political building of ＇transnational and peaceful politics＇ aimed at the growth of peaceful and ＇progressive＇ social relations among States and how the ＇peaceful politics＇ are subjects that engage the complexity and the deep-rooted issues of State facing to the ＇first globalization＇ and the ＇end of century crisis＇.展开更多
基金Under the auspices of the National Natural Science Foundation of China(No.42277097,41425007)the High-level Team Project of China Agricultural University,Chongqing Technology Innovation and Application Development Project(cstc2021jscx-cylh0024)the Deutsche Forschungsgeminschaft(DFG)-328017493/GRK 2366(No.Sino-German IRTG AMAIZE-P)。
文摘Atmospheric nitrogen(N)deposition has experienced significant change because of anthropogenic emissions,thereby exerting a pronounced impact on global ecosystem services.With the rapid development of industry and agriculture and the swift expansion of urban areas in China since the 1980s,reactive nitrogen(Nr)emissions and N deposition have substantially increased.In pursuit of im-proving air quality,China has implemented a series of environmental protection policies and undertaken diverse measures to reduce pol-lutant emissions.This paper is a review of multivariate data sources of atmospheric N deposition based on the results of literature from 1980 to 2023,and the original data from 1980 to 2020 are summarized,counted and calculated.The main findings are as follows:1)the annual average atmospheric N deposition ranged from approximately 20-40 kg/(ha·yr),with the variability primarily linked to different assessment methods;2)regional disparities were evident in the spatial distribution of N deposition,with elevated values concentrated in areas with intense Nr emissions;3)atmospheric N deposition significantly declined after 2010,particularly the deposition of oxidized N,while reduced N deposition remained stable.These results reflect the effects of China's serious control policies on nitrogen oxide(NO.)emissions and strengthen the importance of agricultural NH3 emission mitigation.This study contributes to a comprehensive understanding of the N dynamics in the emission-deposition process,and provides a scientific foundation for the research of environmental protection,climate change,and sustainable development.
基金supported by the National Natural Science Foundation of China(No.71571127)the National Natural Science Youth Foundation of China(No.72001181).
文摘Based on the number of customers and the server’s workload,this paper proposes a modified Min(N,D)-policy and discusses an M/G/1 queueing model with delayed randomized multiple vacations under such a policy.Applying the well-known stochastic decomposition property of the steady-state queue size,the probability generating function of the steady-state queue length distribution is obtained.Moreover,the explicit expressions of the expected queue length and the additional queue length distribution are derived by some algebraic manipulations.Finally,employing the renewal reward theorem,the explicit expression of the long-run expected cost per unit time is given.Furthermore,we analyze the optimal policy for economizing the expected cost and compare the optimal Min(N,D)-policy with the optimal N-policy and the optimal D-policy by using numerical examples.
基金Financial support for this work is provided by the Shunde Environment ProtectionTransportation and Urban Administration Bureau(no.0851-1361FS02CL51)+5 种基金the Guangdong Provincial Science and Technology Plan Projects(no.2014A050503019)Guangzhou Environmental Protection Bureau(no.x2hjB2150020)supported by the funding of State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complexthe project of Atmospheric Haze Collaboration Control Technology Design(no.XDB05030400)from Chinese Academy of Sciencesthe Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund(U1501501)(the second phase)the Guangdong Provincial Engineering and Technology Research Center for Environmental Risk Prevention and Emergency Disposal(no.b2152120)
文摘To develop a sound ozone（O_3） pollution control strategy,it is important to well understand and characterize the source contribution due to the complex chemical and physical formation processes of O_3.Using the ＂Shunde＂ city as a pilot summer case study,we apply an innovative response surface modeling（RSM） methodology based on the Community Multi-Scale Air Quality（CMAQ） modeling simulations to identify the O_3 regime and provide dynamic analysis of the precursor contributions to effectively assess the O_3 impacts of volatile organic compound（VOC） control strategy.Our results show that Shunde is a typical VOC-limited urban O_3 polluted city.The ＂Jiangmen＂ city,as the main upper wind area during July 2014,its VOCs and nitrogen oxides（NO_x） emissions make up the largest contribution（9.06%）.On the contrary,the contribution from local（Shunde） emission is lowest（6.35%） among the seven neighbor regions.The local VOCs industrial source emission has the largest contribution comparing to other precursor emission sectors in Shunde.The results of dynamic source contribution analysis further show that the local NO_x control could slightly increase the ground O_3 under low（10.00%） and medium（40.00%）reduction ratios,while it could start to turn positive to decrease ground O_3 under the high NO_x abatement ratio（75.00%）.The real-time assessment of O_3 impacts from VOCs control strategies in Pearl River Delta（PRD） shows that the joint regional VOCs emission control policy will effectively reduce the ground O_3 concentration in Shunde.
文摘Loess Plateau is the most serious region of soil and water loss in China and the world. The sediment carried into the Yellow River amounts to 1.6 billion tons every year. This paper reviews the factors and reasons for erosion in this area, and puts forward a comprehensive controlling policy on the basis of the principles of ecology and practise of Chinese scientists for 40 years. In conformity with the policy, a number of technical measures for controlling soil and water loss are suggested.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFC3702702)National Natural Science Foundation of China(Grant No.82103871).
文摘Clean air is fundamental to human health.Approximately 99%of the global population has been exposed to concentrations higher than the World Health Organization’s recommendations.Moreover,adverse health effects have been observed at much lower pollution levels than previously studied.China has experienced periods of severe air pollution over the past few decades.To improve air quality and safeguard public health,the government has implemented several progressively tightened policies.Emission control policies were first proposed in 2005.
文摘Achieving robust walking for different stairs is one of the most challenging tasks for quadruped robots in real world.Traditional model-based methods heavily rely on environmental factors,are burdened by intricate modelling complexities,and lack generalizability.The potential for advancements in adaptive locomotion control,often impeded by complex modelling processes,can be substantially enhanced through the application of Reinforcement Learning(RL).In this paper,a learning-based method is proposed to directionally enhance the stair-climbing skill of quadruped robots under different stair conditions.First,the general policy model based on proprioceptive perception is trained as a pre-training model.Then,the pre-training model was initialized,and different terrain information from the stairs was introduced for customized training to enhance the stair-climbing skill without affecting the existing locomotion performance.Finally,the customized control policy is deployed to the real robot to realize motion control in real environments.The experimental results demonstrate that the customized control policy can significantly improve the motion performance of quadruped robots when facing complex stair terrains and has certain generalizability in other complex terrains.The proposed algorithm can be extended to various terrestrial environments.
基金supported by the National Key Research and Development Program of the Ministry of Science and Technology of China(No.2019YFC0214805)the National Social Science Foundation of China(No.21AZD060)+1 种基金the National Natural Science Foundation of China(Nos.71810107001 and 72073003)the 111 Project Urban Air Pollution and Health Effects(No.B20009),Peking University。
文摘China has put great efforts into air pollution control over the past years and recently committed to its most ambitious climate target.Cost and benefit analysis has been widely used to evaluate the control policies in terms of past performance,future reduction potential,and direct and indirect impacts.To understand the cost and benefit analysis for air pollution control in China,we conducted a bibliometric review of more than 100 studies published over the past two decades,including the current research progress,most commonly adopted methods,and core findings.The control target in cost and benefit analysis has shifted in three stages,from individual and primary pollution control,moving to joint prevention of multiple and secondary pollutants,and then towards synergistic control of air pollution and carbon.With the expansion of the research scope,the integrated assessment model has gradually demonstrated the necessity for long-term ex-anti policy simulation,especially for dealing with complex factors.To ensure long-term air quality,climate,public health,and sustainable economic development,substantial evidence from published studies has suggested that China needs to continue its efforts in the upstream adjustment of the energy system and industrial structure with multi-regional and-sector collaboration.This cost and benefit review paper provides decision-makers with the fundamental information and knowledge gaps in air pollution control strategies in China,and direction for facing future challenges.
基金supported by the National Key Research and Development Program(Nos.2019YFC0214800 and 2016YFC0208004)the National Natural Science Foundation of China(Nos.41822505 and 42061130213)+1 种基金supported by the Royal Society of the UK through the Newton Advanced Fellowship(No.NAFR1201166)the Tsinghua University Initiative Scientific Research Program(No.2019Z02CAU)。
文摘China’s emission control for nonroad diesel mobile machinery(NDMM)must deal with a fast increase in stock as well as regulations that are two decades behind those for on-road vehicles.This study provides the first large-scale review and evaluation of China’s NDMM policies,along with emission measurements and an investigation on diesel fuel quality.The sulfur contents of the investigated diesel declined from 430 ppm(median value)in 2011 to6-8 ppm during the 2017-2018 period.The emission control of NO_(x)and PM greatly improved with the shift from the China II to China IV standards,as demonstrated by engine tests and field NO_(x)measurements.However,the NO_(x)emission factors for non-type-approved engines were approximately twice the limits of the China II standards.Emission compliance based on bench tests was not sufficient to control actual emissions because the field-measured NO_(x)emission factors of all machinery ranged from 24%to 225%greater than the respective emission limits for the engines.These circumstances adversely affected the effectiveness of the regulations and policies for China’s emission control of NDMM.Nevertheless,the policies on new and in-use NDMM,as well as diesel fuel quality,prevented NO_(x)and PM emissions amounting to 4.4 Tg and 297.8 Gg during the period 2008-2017,respectively.The emission management strategy contributed to enhancing the international competitiveness of China’s NDMM industries by promoting advanced technologies.For effective NDMM emission control in the future,portable testing and noncontact remote supervision should be strengthened;also,the issue of noncompliant diesel should be addressed through rigorous control measures and financial penalties.
基金Financial and data support for this work is provided by the U.S. Environmental Protection Agency (No. GS-10F-0205T)partly supported by the funding of Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control (No. h2xj D612004 Ш )+1 种基金the funding of State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex (No. SCAPC201308)the project of Atmospheric Haze Collaboration Control Technology Design (No. XDB05030400) from Chinese Academy of Sciences
文摘This article describes the development and implementations of a novel software platform that supports real-time, science-based policy making on air quality through a user-friendly interface. The software, RSM-VAT, uses a response surface modeling（RSM） methodology and serves as a visualization and analysis tool（VAT） for three-dimensional air quality data obtained by atmospheric models. The software features a number of powerful and intuitive data visualization functions for illustrating the complex nonlinear relationship between emission reductions and air quality benefits. The case study of contiguous U.S.demonstrates that the enhanced RSM-VAT is capable of reproducing the air quality model results with Normalized Mean Bias 〈 2% and assisting in air quality policy making in near real time.
基金National Natural Science Foundation of China （Youth Foundation）： Study on the Operating Efficiency and Energy Consumption Optimization Methods of the Regional Passenger Transport System （71201006） （Xuesong FENG）
文摘With the rapid development of economy and motorization, the traffic congestion and environmental problems have become more and more serious day by day in Beijing. Therefore, traffic control policies have been gradually adopted by Beijing municipal government since 2008, so as to ease traffic and environmental problems. In this paper, the background and current situation of Beijing to implement traffic control policies are introduced, and also this measure is analyzed and evaluated from traffic effect, environmental effect, motor vehicle development, urban road development, public transport development, and balance between supply and demand, etc. Finally, related conclusions are drawn up as follows： an induced traffic volume will be generated by traffic control policies, and the effect of the traffic control will be erased by the natural growth rate of motor vehicles in three years; public traffic service should be improved for better making traffic control policies; the traffic congestion and environmental problems are alleviated by traffic control policies in the short term, but can＇t be fundamentally solved in the long run; traffic control policies should cooperate with other traffic demand management policies for reducing demands, and traffic condition should be optimized in both time and space, so that the traffic congestion and environmental problems will be fundamentally solved.
文摘With the rapid development of economic activities in cities and construction industry in our country, the number of construction projects has been increasing. At the same time, this has promoted the development of land surveying and mapping work in our country to a certain extent. Land surveying and mapping is a complicated and arduous systematic work in our country, which mainly includes the surveying and mapping of planning and construction land, daily land surveying and mapping and various cadastral map data surveying and mapping systems. As the basic work of construction engineering, the quality of land surveying and mapping directly affects the overall progress of construction. Based on this, this paper analyzes the factors affecting the quality of land surveying and mapping and the control measures.
基金The National Natural Science Foundation of China(No60403027)
文摘To enhance the practicability of the trust negotiation system, an agent based automated trust negotiation model （ABAM） is proposed. The ABAM introduces an agent to keep the negotiation process with no human intervention. Meanwhile, the ABAM specifies the format of a meta access control policy, and adopts credentials with flexible format to meet the requirements of access control policies instead of disclosing the whole contents of a certificate. Furthermore, the ABAM uses asymmetric functions with a high security intensity to encrypt the transmitting message, which can prevent information from being attacked. Finally, the ABAM presents a new negotiation protocol to guide the negotiation process. A use case is studied to illuminate that the ABAM is sound and reasonable. Compared with the existing work, the intelligence, privacy and negotiation efficiency are improved in the ABAM.
基金supported by the National Key Research and Development Program of China(Nos.2016YFC0208000,2019YFC0214800 and 2016YFC0201504)the National Natural Science Foundation of China(No.62033012)。
文摘In recent years,great efforts have been devoted to reducing emissions from mobile sources with the dramatic growth of motor vehicle and nonroad mobile source populations.Compilation of a mobile source emission inventory is conducive to the analysis of pollution emission characteristics and the formulation of emission reduction policies.This study summarizes the latest compilation approaches and data acquisition methods for mobile source emission inventories.For motor vehicles,a high-resolution emission inventory can be developed based on a bottom-up approach with a refined traffic flow model and real-world speed-coupled emission factors.The top-down approach has advantages when dealing with macroscale vehicle emission estimation without substantial traffic flow infrastructure.For nonroad mobile sources,nonroad machinery,inland river ships,locomotives,and civil aviation aircraft,a top-down approach based on fuel consumption or power is adopted.For ocean-going ships,a bottom-up approach based on automatic identification system(AIS)data is adopted.Three typical cases are studied,including emission reduction potential,a cost-benefit model,and marine shipping emission control.Outlooks and suggestions are given on future research directions for emission inventories for mobile sources:building localized emission models and factor databases,improving the dynamic updating capability of emission inventories,establishing a database of emission factors of unconventional pollutants and greenhouse gas from mobile sources,and establishing an urban high temporalspatial resolution volatile organic compound(VOC)evaporation emission inventory.
基金supported by National Natural Science Foundationof China(Nos.61174124 and 61233003)Research Fund for DoctoralProgram of Higher Education of China(No.20123402110029)Natural Science Research Program of the Anhui High Education Bureau of China(No.KJ2012A286)
文摘The proliferation of streaming service system in various application areas gains increasing importance and also poses more challenges in the research of streaming service system. In this paper, we propose a novel dynamic model composed of a set of differential equations to describe the evolution of streaming service systems. And in the model, we focus on how the policies for admission control and peer selection influence on the system. We first introduce a flexible abstraction of streaming service systems. The abstraction is generally enough to capture the essences of streaming service systems with different structures, physical characteristics,software protocols and client behaviors. Then, by analyzing the state which is defined as the number of requests, a novel dynamic model is developed in microscopic scale to characterize the behaviors of streaming service systems. The model proposed in this paper demonstrates the interactions between clients and servers and also between different servers. The interactions are primarily influenced by the admission control policy and peer selection policy. Finally, some experiments are designed to verify the validation and reasonability of the model.
基金We acknowledge that this work was supported by the science and technology innovation fund of Henan Agricultural University,No.KJCX2016A04Henan province institution of higher learning youth backbone teachers training program,No.2016GGJS-036Henan Provincial Department of Science and Technology Research Project under Grant 192102110205.
文摘As fresh agricultural products are perishable and vulnerable,reducing inventory cost is a strategic target for supply chain enterprises.How to design a reliable multi-echelon inventory control policy is still a great challenge.Therefore,the inventory cost of a three-level fresh agricultural products inventory system was firstly mathematically analyzed.Then,the simulation-based optimization model of the multi-echelon inventory system for fresh agricultural products was proposed by using the Flexsim simulation software and the improved particle swarm optimization algorithm.Finally,the multi-echelon inventory system is simulated based on a large number of survey data.Simulation results demonstrate that the proposed simulation-based optimization model of multi-echelon inventory system for fresh agricultural products can provide decision-making and technical support for the formulation of inventory control policy,and also it shows that the modeling of system simulation is an effective method to solve the problem of complex system.
基金Shaanxi Social Science Project(2022YA14)Xi'an Social Science Planning Project(23JX66)+1 种基金Fundamental Research Funds for the Central Universities(KYFZ23008)Proof of Concept Foundation of Xidian University Hangzhou Institute of Technology under Grant No.GNYZ2023ZC0503.
文摘Sulfur dioxide(SO_(2))is a typical pollutant that affects human health,climate,and environmental and ecological conditions.China has been experiencing high concentrations of SO_(2),particularly in urban areas,since the 1990s.In 2010,a"joint prevention and control"(JPC)policy was issued to address air pollution problems and strengthen the regulation of SO_(2)emissions.This study aimed to describe the mitigation effects of this policy on SO_(2)emissions in 116 Chinese cities from 2003 to 2017.We applied global and local Moran's I indices to confirm the presence of significant spatial autocorrelation in SO_(2)emissions and constructed four spatial models to assess the effect of the JPC policy in reducing SO_(2)emissions and its transmission mechanism.We found that the policy decreased SO_(2)emissions by 1.89×10^(4)tons,S0_(2)intensity by 1.70 tons per km^(2),and S0_(2)per capita of 158.49 tons per 10,000 people in each city,on average,all of which are significant changes.The empirical results also show that population growth,economic structure,and environmental protection significantly decrease SO_(2)emissions.Finally,we recommended policies to encourage regional cooperation under the JPC policy,with the aim of promoting furtherreductions in SO_(2)emissions.
文摘Empirical research on the effect of family size on child education is complicated by the endogeneity of family size. This study exploits plausibly exogenous changes in family size caused by China＇s population control policy to estimate the causal relationship between family size and child education outcomes. The results show that, compared to an only child, a person with an additional sibling will have an approximate seventeen percentage points lower likelihood of completing middle school in China. Separate regressions across individual characteristics reveal that much of this negative effect appears to be driven by the cohorts born in earlier years after the policy, and children with the highest birth order within a family.
文摘Epidemiological studies have shown that infection with the human immunodeficiency virus(HIV) is an influential risk factor for infection with Mycobacterium tuberculosis(MTb),the rapid progression of the initial infection to active tuberculosis(TB),and the reactivation of latent TB infection.MTb infection is also one of the most common opportunistic infections in people with HIV,including AIDS patients receiving anti-retroviral therapy.Given the prevalence of HIV infection,the incidence of TB infection,which had begun to decline,is facing a severe situation.HIV associated with TB exerts an immense burden on the public health-care system,especially in countries with high incidences of HIV infection.Therefore,the global policies for the prevention and control of TB should be revised.Moreover,an increased investment in TB control has to be guaranteed.The purpose of this review is to summarize the recent progress in the prevention,treatment,and control of HIV and TB co-infection.
基金This research was supported by the National Natural Science Foundation of China(No.71571127)the funding of V.C.&V.R.Key Lab of Sichuan Province(SCVCVR2019.05VS)the Sichuan Science and Technology Program(Nos.2020YFS0318,2019YFS0155,2019YFS0146,2020YFG0430,2020YFS0307).
文摘This paper investigates a multi-component repairable system with double threshold control policy.The system is composed of n identical and independent components which operate simultaneously at the beginning,and it is down when the number of operating components decreases to k−1(k≤n).When the number of failed components is less than the value L,the repairman repairs them with a low repair rate.The high repair rate is activated as soon as L failed components present,and continues until the number of failed components drops to the value N−1.Applying the matrix analytical method,the Laplace transform technique and the properties of the phase type distribution,various performance measures including the availability,the rate of occurrence of failures,and the reliability are derived in transient and stationary regimes.Further,numerical examples are reported to show the behaviour of the system.
文摘The Inter-Parliamentary Union was formed in 1889, gathering, initially, 38 British and French parliamentarians. The IPU （guided, from 1901 up to 1908, by Fredreric Passy and William Randall Cremer）, was to support and reinforce the objective of extending arbitration as a ＇peaceful tool＇ for resolving the dispute between states. The aftermath of the First World War marked a decisive step forward in the development of a strong liberal internationalist milieux which promoted a peaceful order based on the international rule of law. This paper summarizes some issues of ongoing research and it focuses on two key topics： the rise of parliamentary control of foreign policy and the making of ＇parliamentary diplomacy＇. Besides, it tried to elucidate, from another point of view, the political building of ＇transnational and peaceful politics＇ aimed at the growth of peaceful and ＇progressive＇ social relations among States and how the ＇peaceful politics＇ are subjects that engage the complexity and the deep-rooted issues of State facing to the ＇first globalization＇ and the ＇end of century crisis＇.
