The paper had introduced researches on urban forest park and analyzed its particularity.In terms of elimination of externality during development and tourism consumption process of urban forest park,real estate agent ...The paper had introduced researches on urban forest park and analyzed its particularity.In terms of elimination of externality during development and tourism consumption process of urban forest park,real estate agent had been introduced and two assumptions had been proposed to eliminate externality.As for elimination of externality during development of urban forest park,right to use planning land for urban forest park and surrounding land for real estate development would be sold to estate agent who would develop urban forest park and commodity house;the management of forest urban park would be undertaken by tourism development companies for which estate agent would make compensation.As for elimination of externality during tourism consumption process,it would control with policies and laws,or establish ticket system.As the study hadn't been conducted on policies about urban land and real estate,the feasibility of the first assumption needed to be further studied by environmental economists.展开更多
Understanding the connotation and principles of ecological compensation in water source reserve areas is the basis and guarantee for establishing and improving the ecological compensation mechanism of water source res...Understanding the connotation and principles of ecological compensation in water source reserve areas is the basis and guarantee for establishing and improving the ecological compensation mechanism of water source reserve areas.First,this paper reviews the three stages of ecological compensation research progress.Based on the review,using the theory of externality,the ecological environment system of water source reserve areas is then analyzed.This paper argues that the connotation of ecological compensation in water source reserve areas is a kind of institutional arrangement,which is designed to internalize externalities.Finally,based on the understanding of the connotation of ecological compensation in water source reserve areas,five principles for establishing and improving the ecological compensation mechanism are proposed,including the principle of fairness and justice,the principle of equivalence of equality and responsibility,the principle of flexibility and effectiveness,the principle of "earmark funds,and implementation by law," and the principle of government compensation supplemented with market compensation.展开更多
In the context of global climate change,the internalization of negative externality,which is brought about by the traditional mode of economic growth,has become an inevitable choice.In order to achieve the internaliza...In the context of global climate change,the internalization of negative externality,which is brought about by the traditional mode of economic growth,has become an inevitable choice.In order to achieve the internalization,it is necessary to make innovations on the market mechanism and system,find the value of environmental capital,establish a new mode of economic growth based on environmental capital,and then transform the environmental capital,an exogenous factor of economic growth,into an endogenous factor.Of this,the key of market mechanism and system innovation is the financial innovation that is based on environmental capital and negative externality;the government defines the initial property right of environmental resources and establishes environment energy trading market,so as to guide enterprises to trade environmental resources(represented by carbon emission permit trading) based on the Clean Development Mechanism,and to vigorously develop environmental finance and carbon finance.展开更多
According to the theories of institutional economics and development economics,the positive and negative externality of rural labor force flowing from central and western regions and into eastern regions of China were...According to the theories of institutional economics and development economics,the positive and negative externality of rural labor force flowing from central and western regions and into eastern regions of China were analyzed,and then it was proposed that it is necessary to positive externality,rather than take"household register"measures to solve the problem simply.展开更多
Externality;the term can define as a positive or negative impact from either production or consumption of goods or services.Services provided by particular location have very specific dependency on spatial characteris...Externality;the term can define as a positive or negative impact from either production or consumption of goods or services.Services provided by particular location have very specific dependency on spatial characteristics of that region.A region’s distinct characteristics make it ecologically unique from other such regions.Ecosystem services are offered by these regions thus differ according to these unique ecological features.In this particular study,artificially imposed expansion of coastal shrimp farming towards the inland and its impact over paddy cultivation have been addressed.Optimization of the extent of this manipulative coastal expansion has been supported by little modification of a previously described model.Here the investment prediction for both shrimp and paddy farming has been investigated by calculating net present value(NPV).Shrimp farming has very specific externality on local ecosystem services.In this particular case,some contradictory results are presented and with respect to positive or negative externality;but the externalities are strong.NPV results indicate that there is no long-term profitability in case of shrimp farming.Hence,an overall externality of shrimp farming has been described in context of this study.展开更多
Using data from two well-known individual surveys in China,we estimate human capital externality.We find a positive and statistically significant effect of city-level human capital on individual earnings.Fixed-effects...Using data from two well-known individual surveys in China,we estimate human capital externality.We find a positive and statistically significant effect of city-level human capital on individual earnings.Fixed-effects estimates show a one-year increase in city average education could increase individual earnings between 7.3%and 8.9%.Our IV estimate indicates a 7.6%increase.This finding confirms a long-held belief by economists that there are external benefits of education that are not captured by the individuals who invested in human capital.By extension our finding also offers a justification for an active role of the government in promoting education.We also find that the estimated effect of human capital externality is larger in coastal cities than in non-coastal cities and is larger in the non-state sector than in the state sector.We ascribe these heterogeneities to differences in institutional and technological environments across cities and sectors.展开更多
The study conducted here is an attempt to answer the questions of where China stands as a recipient,what multilateral and bilateral aid has brought to China,and why.For the convenience of discussion,I shall concentrat...The study conducted here is an attempt to answer the questions of where China stands as a recipient,what multilateral and bilateral aid has brought to China,and why.For the convenience of discussion,I shall concentrate on:The period after 1979 when China started its economic reformOfficial Development Assistance (ODA) commitments and types of flows,andThe OECD figures.展开更多
Computational phantoms play an essential role in radiation dosimetry and health physics.Although mesh-type phantoms offer a high resolution and adjustability,their use in dose calculations is limited by their slow com...Computational phantoms play an essential role in radiation dosimetry and health physics.Although mesh-type phantoms offer a high resolution and adjustability,their use in dose calculations is limited by their slow computational speed.Progress in heterogeneous computing has allowed for substantial acceleration in the computation of mesh-type phantoms by utilizing hardware accelerators.In this study,a GPU-accelerated Monte Carlo method was developed to expedite the dose calculation for mesh-type computational phantoms.This involved designing and implementing the entire procedural flow of a GPUaccelerated Monte Carlo program.We employed acceleration structures to process the mesh-type phantom,optimized the traversal methodology,and achieved a flattened structure to overcome the limitations of GPU stack depths.Particle transport methods were realized within the mesh-type phantom,encompassing particle location and intersection techniques.In response to typical external irradiation scenarios,we utilized Geant4 along with the GPU program and its CPU serial code for dose calculations,assessing both computational accuracy and efficiency.In comparison with the benchmark simulated using Geant4 on the CPU using one thread,the relative differences in the organ dose calculated by the GPU program predominantly lay within a margin of 5%,whereas the computational time was reduced by a factor ranging from 120 to 2700.To the best of our knowledge,this study achieved a GPU-accelerated dose calculation method for mesh-type phantoms for the first time,reducing the computational time from hours to seconds per simulation of ten million particles and offering a swift and precise Monte Carlo method for dose calculation in mesh-type computational phantoms.展开更多
The effects of the high pressure die casting(HPDC)processes on porosity,microstructure,and mechanical properties of heat-treatment-free aluminum silicon(Al-Si)alloys have long been a focal point in automotive die-cast...The effects of the high pressure die casting(HPDC)processes on porosity,microstructure,and mechanical properties of heat-treatment-free aluminum silicon(Al-Si)alloys have long been a focal point in automotive die-casting research.In this work,the combined effect of shot sleeve materials and slow shot speeds on porosity,microstructure and mechanical properties of a newly designed HPDC Al-Si alloy was investigated.Results show that employing a ceramic shot sleeve or increasing the slow shot speed significantly reduces both the average size and area fraction of externally solidified crystals(ESCs),as well as the average pore size and volume fraction.When the slow shot speed is increased from 0.05 m·s^(-1)to 0.1 m·s^(-1),the pore volume fraction decreases by 10.2%in steel-shot-sleeve samples,compared to a substantial 67.1%reduction in ceramic-shot-sleeve samples.At a slow shot speed of 0.1 m·s^(-1),castings produced with a ceramic shot sleeve exhibit superior mechanical properties:8.3%higher yield strength,17.4%greater tensile strength,and an 81.4%improvement in elongation,relative to those from a steel shot sleeve.These findings provide valuable insights for minimizing porosity and coarse ESCs in die castings,offering promising potential for broader industrial applications.展开更多
Traditional strategies for designing hyperhalogens,superatoms with exceptional electron-withdrawing capacity,rely on complex superhalogen assembly,posing significant experimental challenges.Here,we introduce a non-inv...Traditional strategies for designing hyperhalogens,superatoms with exceptional electron-withdrawing capacity,rely on complex superhalogen assembly,posing significant experimental challenges.Here,we introduce a non-invasive dual external field(DEF) approach combining solvent effects and an oriented external electric field(OEEF) to construct hyperhalogens,as demonstrated by density functional theory(DFT) calculations.Our DEF strategy proves versatile,successfully designing hyperhalogens not only in simplified Ag_n^(-) model systems but also in the experimentally synthesized Ag_(25) nanocluster.Using the 3D Ag_(19)^(-) structure as a model,we further reveal the DEF's pivotal role in O_(2) activation,where solvent-OEEF synergy induces tunable O-O bond elongation and charge transfer,proportional to field strength.Our findings establish a field-driven paradigm for hyperhalogen design that preserves native cluster composition,providing a theoretical foundation for tailoring high-performance catalysts through precise activesite modulation.展开更多
Amphibious vehicles are more prone to attitude instability compared to ships,making it crucial to develop effective methods for monitoring instability risks.However,large inclination events,which can lead to instabili...Amphibious vehicles are more prone to attitude instability compared to ships,making it crucial to develop effective methods for monitoring instability risks.However,large inclination events,which can lead to instability,occur frequently in both experimental and operational data.This infrequency causes events to be overlooked by existing prediction models,which lack the precision to accurately predict inclination attitudes in amphibious vehicles.To address this gap in predicting attitudes near extreme inclination points,this study introduces a novel loss function,termed generalized extreme value loss.Subsequently,a deep learning model for improved waterborne attitude prediction,termed iInformer,was developed using a Transformer-based approach.During the embedding phase,a text prototype is created based on the vehicle’s operation log data is constructed to help the model better understand the vehicle’s operating environment.Data segmentation techniques are used to highlight local data variation features.Furthermore,to mitigate issues related to poor convergence and slow training speeds caused by the extreme value loss function,a teacher forcing mechanism is integrated into the model,enhancing its convergence capabilities.Experimental results validate the effectiveness of the proposed method,demonstrating its ability to handle data imbalance challenges.Specifically,the model achieves over a 60%improvement in root mean square error under extreme value conditions,with significant improvements observed across additional metrics.展开更多
In order to investigate the effect of die wall thickness on morphologies of defect band,a stepped mold with a wall thickness of 5 mm,4 mm,3 mm,2 mm,and 1 mm was designed to carry out high pressure die casting experime...In order to investigate the effect of die wall thickness on morphologies of defect band,a stepped mold with a wall thickness of 5 mm,4 mm,3 mm,2 mm,and 1 mm was designed to carry out high pressure die casting experiments with AlSi10 MgMn alloy.For castings with wall thickness of 2-4 mm,the ratio of the mean defect band width(w)and mean grain size(d)in the defect band(w/d)ranges 7-18,while it increases to 24.47 for the 5 mm-thick casting.This difference is related with the filling speed and the distribution of externally solidified crystals(ESCs).The mold flow analysis indicates that the filling speed decreases from 25.41 m·s^(-1)to 11.07 m·s^(-1)when wall thickness increases from 2 mm to 5 mm.Due to the decreasing filling speed along the wall thickness,ESCs gradually diffuse from the center to the defect band,which keep the shear strength in the defect band at a high-level during filling.Meanwhile,the shear strength generated during the filling also decreases as the shear rate drops.Finally,the defect bands in the 5 mm-thick region become widen and indistinct,and the porosity is as high as 5.25%.展开更多
Electroslag remelting(ESR) is an important metallurgical process for producing high-purity materials with homogeneous compositions and sound microstructures,and its typical products are ingots or simple castings.The c...Electroslag remelting(ESR) is an important metallurgical process for producing high-purity materials with homogeneous compositions and sound microstructures,and its typical products are ingots or simple castings.The core principle involves the resistive melting of a consumable electrode within a slag pool,followed by the refining of molten metal droplets as they traverse the slag,and subsequent sequential solidification in a water-cooled mold.However,conventional ESR processes face limitations in producing large or complex-shaped components,enhancing production efficiency,achieving highly specialized microstructures,and meeting ultra-high purity demands for advanced applications.Advanced composite ESR technologies have been developed to overcome these limitations by innovatively modifying key process aspects.For instance,electrode systems are improved using vibration,rotation,or multiple electrodes.Enhanced mold design and solidification control are achieved through techniques including conductive molds,mold rotation,and ingot withdrawal.Precise control of the process is realized through the use of protective gas,vacuum,or elevated pressure,as well as the application of external fields such as magnetic fields or ultrasonic vibration.This review comprehensively summarizes these advanced techniques,examining their principles and characteristics,and discussing their specific advantages and challenges.展开更多
Objective:To understand the current awareness and willingness to learn about the use of out-of-hospital automated external defibrillators(AEDs)in Deyang City,providing a basis for improving the success rate of rescue ...Objective:To understand the current awareness and willingness to learn about the use of out-of-hospital automated external defibrillators(AEDs)in Deyang City,providing a basis for improving the success rate of rescue operations.Methods:A questionnaire survey was conducted among residents in Deyang City from January 2025 to October 2025,covering residents’basic information,awareness of AED-related knowledge,and attitudes towards AED usage.Results:A total of 1,886 questionnaires were collected,with 1,823 valid questionnaires,yielding an effective rate of 96.66%.Among the 1,823 respondents,692(37.96%)had received cardiopulmonary resuscitation(CPR)-related learning or training,619(33.96%)could accurately describe the name of an AED,417(22.87%)could clearly describe the function of an AED,and 308(16.89%)could accurately describe how to use an AED.Among them,1,549(84.97%)were willing to provide assistance to patients experiencing cardiac arrest;1,731(94.95%)were willing to provide assistance under the premise of knowing how to use an AED;and 1,750(95.99%)were willing to learn about AED-related knowledge.Among the 91 individuals unwilling to provide rescue,75 responded with reasons.Among them,36 cases(48.00%)were reluctant to rescue due to a lack of relevant first aid knowledge,32 cases(42.67%)expressed concerns about exacerbating the patient’s condition due to improper operation,and 4 cases(5.33%)were unwilling to interact with strangers due to personal reasons.Conclusion:Currently,residents in Deyang City have limited knowledge about AEDs but demonstrate a strong willingness to learn and apply them.Measures need to be taken to enhance their understanding and application of AEDs.展开更多
This paper examines the relationship between the Samuelson rule for efficient provision of stock externality and unilateral transfers for equalization of mitigation costs among the agents. Using a generic model of sto...This paper examines the relationship between the Samuelson rule for efficient provision of stock externality and unilateral transfers for equalization of mitigation costs among the agents. Using a generic model of stock externality provisions, we proved that the revised Samuelson rule that allows transfers is a necessary and sufficient condition for efficient provision of stock externalities. In addition, selection of social welfare weights of the agents plays a key role in directions and magnitudes of the transfers. We discuss the implications of the revised Samuelson rule in economic modeling of climate change, an empirical case of stock externality, through numerical simulations in the RICE model.展开更多
Titanium alloy has the advantages of high strength,strong corrosion resistance,excellent high and low temperature mechanical properties,etc.,and is widely used in aerospace,shipbuilding,weapons and equipment,and other...Titanium alloy has the advantages of high strength,strong corrosion resistance,excellent high and low temperature mechanical properties,etc.,and is widely used in aerospace,shipbuilding,weapons and equipment,and other fields.In recent years,with the continuous increase in demand for medium-thick plate titanium alloys,corresponding welding technologies have also continued to develop.Therefore,this article reviews the research progress of deep penetration welding technology for medium-thick plate titanium alloys,mainly covering traditional arc welding,high-energy beam welding,and other welding technologies.Among many methods,narrow gap welding,hybrid welding,and external energy field assistance welding all contribute to improving the welding efficiency and quality of medium-thick plate titanium alloys.Finally,the development trend of deep penetration welding technology for mediumthick plate titanium alloys is prospected.展开更多
Additive manufacturing(AM)technology has demonstrated significant potential in the green,lightweight,and functional development of metal materials,offering greater freedom and flexibility in the manufacturing process....Additive manufacturing(AM)technology has demonstrated significant potential in the green,lightweight,and functional development of metal materials,offering greater freedom and flexibility in the manufacturing process.However,the microstructural heterogeneity and mechanical property anisotropy of nickel-based superalloys along the build direction,stemming from thermal cycling,limit their widespread application in the aerospace industry.The proposed hybrid manufacturing process introduces external energy fields(thermal,ultrasonic,magnetic fields)into the forming processes,offering an innovative pathway to overcome the limitations of AM superalloys.This paper systematically discusses the influence of energy fields on the AM process of nickel-based superalloys,focusing on key issues such as cracking,porosity,microstructural heterogeneity,and mechanical property.Various energy fields modulate the melt pool dynamics and solidification process through distinct mechanisms.However,there remain several unresolved challenges and controversies regarding their mechanisms,particularly concerning the microstructural evolution under the synergistic effects of multiple energy fields.To address this issue,current studies predominantly focus on experimental validation,with a lack of unified theoretical models and numerical simulations,which limits the further development of energy field optimization strategies.Accordingly,the roles and advantages of various energy fields in AM of nickel-based superalloys are summarized.And engineering challenges are highlighted,such as multi-field synergistic control strategies,quantitative prediction models for microstructure-property,and energy field optimization methods for practical applications.Finally,the future trends of energy field-assisted AM for high-performance superalloys are discussed,with an outlook on its potential applications in re-manufacturing technologies and integrated equipment.展开更多
This work investigated the dynamic behavior of vertical pipes conveying gas-liquid two-phase flow when subjected to external excitations at both ends.Even with minimal excitation amplitude,resonance can occur when the...This work investigated the dynamic behavior of vertical pipes conveying gas-liquid two-phase flow when subjected to external excitations at both ends.Even with minimal excitation amplitude,resonance can occur when the excitation frequency aligns with the natural frequency of the pipe,significantly increasing the degree of operational risk.The governing equation of motion based on the Euler-Bernoulli beam is derived for the relative deflection with stationary simply supported ends,with the effects of the external excitations represented by source terms distributed along the pipe length.The fourth-order partial differential equation is solved via the generalized integral transform technique(GITT),with the solution successfully verified via comparison with results in the literature.A comprehensive analysis of the vibration phenomena and changes in the motion state of the pipe is conducted for three classes of external excitation conditions:same frequency and amplitude(SFSA),same frequency but different amplitudes(SFDA),and different frequencies and amplitudes(DFDA).The numerical results show that with increasing gas volume fraction,the position corresponding to the maximum vibration displacement shifts upward.Compared with conditions without external excitation,the vibration displacement of the pipe conveying two-phase flow under external excitation increases significantly.The frequency of external excitation has a significant effect on the dynamic behavior of a pipe conveying two-phase flow.展开更多
Electrochemical metallurgy at low temperature(<473 K)shows promise for the extraction and refinement of metals and alloys in a green and sustainable manner.However,the kinetics of the electrodeposition process is g...Electrochemical metallurgy at low temperature(<473 K)shows promise for the extraction and refinement of metals and alloys in a green and sustainable manner.However,the kinetics of the electrodeposition process is generally slow at low temperature,resulting in large overpotential and low current efficiency.Thus,the application of external physical fields has emerged as an effective strategy for improving the mass and charge transfer processes during electrochemical reactions.This review highlights the challenges associated with low-temperature electrochemical processes and briefly discusses recent achievements in optimizing electrodeposition processes through the use of external physical fields.The regulating effects on the optimization of the electrodeposition process and the strategies for select-ing various external physical fields,including magnetic,supergravity,and ultrasonic fields are summarized from the perspectives of equipment and mechanisms.Finally,advanced methods for in-situ characterization of external physical field-assisted electrodeposition processes are reviewed to gain a deeper understanding of metallic electrodeposition.An in-depth exploration of the mechanism by which external physical fields affect the electrode process is essential for enhancing the efficiency of metal extraction at low temperatures.展开更多
Bcakground: Pancreatic pseudocyst (PPC) is a common complication arising from acute or chronic pancreatitis, trauma, or pancreatic duct obstruction. When acute fluid collection persists for 4 - 6 weeks and is encapsul...Bcakground: Pancreatic pseudocyst (PPC) is a common complication arising from acute or chronic pancreatitis, trauma, or pancreatic duct obstruction. When acute fluid collection persists for 4 - 6 weeks and is encapsulated by a fibrous wall, it is classified as a pancreatic pseudocyst. While PPC is generally asymptomatic in many patients, it can manifest with persistent abdominal pain, dyspepsia, intra-cystic infection, and potentially lead to gastrointestinal obstruction in some cases. Although smaller PPCs may resolve spontaneously, larger PPCs tend to be refractory to absorption and often necessitate surgical intervention to prevent complications such as intracystic hemorrhage. Objective: To explore the efficacy of percutaneous catheterization with negative pressure in the treatment of large pancreatic pseudocysts. Methods: The cases of large pancreatic pseudocysts treated in our hospital from 2004 to 2022 were retrospectively collected, and the general condition, operation time, drainage time, feeding time, postoperative complications, hospital stay, cost and follow-up of the patients were analyzed. Results: A total of 132 patients with large pancreatic pseudocysts were collected. The average operation time was 32.4 ± 2.1 min;The retention time of the drainage tube was 30 ± 1.8 days in the percutaneous negative pressure drainage group;The postoperative feeding time was no fasting after local anesthesia drainage;Postoperative complications (bleeding, infection, pancreatic leakage, recurrence, anastomotic leakage, etc.): Two of the 132 patients had recurrent cysts, which were cured by re-puncture and negative pressure drainage. The length of hospital stay was 6 ± 1.1 days;The cost was 11,200 ± 1300 yuan;Follow-up: The follow-up time ranged from 1 to 3 years, and the patients had no discomfort. Conclusion: Percutaneous catheterization and negative pressure drainage can effectively treat large pancreatic pseudocysts. Compared with other treatment methods, it is simple and effective, the postoperative recovery of patients is faster, the physical damage is less, the hospital stay is shorter, and the cost is lower.展开更多
文摘The paper had introduced researches on urban forest park and analyzed its particularity.In terms of elimination of externality during development and tourism consumption process of urban forest park,real estate agent had been introduced and two assumptions had been proposed to eliminate externality.As for elimination of externality during development of urban forest park,right to use planning land for urban forest park and surrounding land for real estate development would be sold to estate agent who would develop urban forest park and commodity house;the management of forest urban park would be undertaken by tourism development companies for which estate agent would make compensation.As for elimination of externality during tourism consumption process,it would control with policies and laws,or establish ticket system.As the study hadn't been conducted on policies about urban land and real estate,the feasibility of the first assumption needed to be further studied by environmental economists.
基金supported by National Social Science Fund "Study on the construction of ecological compensation system and the related policies of the water source protection zone"[Grant Number 14BJY027]Project of Humanities and Social Science Fund of Ministry of Education "Calculation and compensation method of ecological compensation in River Basin"[Grant Number 13YJA790025]
文摘Understanding the connotation and principles of ecological compensation in water source reserve areas is the basis and guarantee for establishing and improving the ecological compensation mechanism of water source reserve areas.First,this paper reviews the three stages of ecological compensation research progress.Based on the review,using the theory of externality,the ecological environment system of water source reserve areas is then analyzed.This paper argues that the connotation of ecological compensation in water source reserve areas is a kind of institutional arrangement,which is designed to internalize externalities.Finally,based on the understanding of the connotation of ecological compensation in water source reserve areas,five principles for establishing and improving the ecological compensation mechanism are proposed,including the principle of fairness and justice,the principle of equivalence of equality and responsibility,the principle of flexibility and effectiveness,the principle of "earmark funds,and implementation by law," and the principle of government compensation supplemented with market compensation.
基金Soft Science Project of Shanghai Science and Technology Development Fund,"Policy Research on Low Carbon Economy based on Carbon Finance Innovation and Low Carbon Industrial Chain"(Grant No.:10692103400)Project of the National Natural Science Foundation of China,"Research on Governance Strategy of Blockholders"(Grant No.:70802015)General project of Shanghai Philosophy and Social Sciences Planning,"The Main Factors that Influence China's Transformation of Economic Development Pattern in the Context of Dual Transitions"(Grant No.:2008BJL003).
文摘In the context of global climate change,the internalization of negative externality,which is brought about by the traditional mode of economic growth,has become an inevitable choice.In order to achieve the internalization,it is necessary to make innovations on the market mechanism and system,find the value of environmental capital,establish a new mode of economic growth based on environmental capital,and then transform the environmental capital,an exogenous factor of economic growth,into an endogenous factor.Of this,the key of market mechanism and system innovation is the financial innovation that is based on environmental capital and negative externality;the government defines the initial property right of environmental resources and establishes environment energy trading market,so as to guide enterprises to trade environmental resources(represented by carbon emission permit trading) based on the Clean Development Mechanism,and to vigorously develop environmental finance and carbon finance.
文摘According to the theories of institutional economics and development economics,the positive and negative externality of rural labor force flowing from central and western regions and into eastern regions of China were analyzed,and then it was proposed that it is necessary to positive externality,rather than take"household register"measures to solve the problem simply.
基金University Grants Commission(UGC)NET fellowship[Ref No.F.16-6(DEC.2016)/2017(NET)]University Grants Commission(UGC)for D S Kothari fellowship reference no.BL/17-18/0490.
文摘Externality;the term can define as a positive or negative impact from either production or consumption of goods or services.Services provided by particular location have very specific dependency on spatial characteristics of that region.A region’s distinct characteristics make it ecologically unique from other such regions.Ecosystem services are offered by these regions thus differ according to these unique ecological features.In this particular study,artificially imposed expansion of coastal shrimp farming towards the inland and its impact over paddy cultivation have been addressed.Optimization of the extent of this manipulative coastal expansion has been supported by little modification of a previously described model.Here the investment prediction for both shrimp and paddy farming has been investigated by calculating net present value(NPV).Shrimp farming has very specific externality on local ecosystem services.In this particular case,some contradictory results are presented and with respect to positive or negative externality;but the externalities are strong.NPV results indicate that there is no long-term profitability in case of shrimp farming.Hence,an overall externality of shrimp farming has been described in context of this study.
基金supported by the National Natural Science Foundation of China,Youth Foundation Program(No.71403292)the National Natural Science Foundation of China,General Program(No.71273288).
文摘Using data from two well-known individual surveys in China,we estimate human capital externality.We find a positive and statistically significant effect of city-level human capital on individual earnings.Fixed-effects estimates show a one-year increase in city average education could increase individual earnings between 7.3%and 8.9%.Our IV estimate indicates a 7.6%increase.This finding confirms a long-held belief by economists that there are external benefits of education that are not captured by the individuals who invested in human capital.By extension our finding also offers a justification for an active role of the government in promoting education.We also find that the estimated effect of human capital externality is larger in coastal cities than in non-coastal cities and is larger in the non-state sector than in the state sector.We ascribe these heterogeneities to differences in institutional and technological environments across cities and sectors.
文摘The study conducted here is an attempt to answer the questions of where China stands as a recipient,what multilateral and bilateral aid has brought to China,and why.For the convenience of discussion,I shall concentrate on:The period after 1979 when China started its economic reformOfficial Development Assistance (ODA) commitments and types of flows,andThe OECD figures.
基金supported by the National Natural Science Foundation of China(Nos.U2167209 and 12375312)Open-end Fund Projects of China Institute for Radiation Protection Scientific Research Platform(CIRP-HYYFZH-2023ZD001).
文摘Computational phantoms play an essential role in radiation dosimetry and health physics.Although mesh-type phantoms offer a high resolution and adjustability,their use in dose calculations is limited by their slow computational speed.Progress in heterogeneous computing has allowed for substantial acceleration in the computation of mesh-type phantoms by utilizing hardware accelerators.In this study,a GPU-accelerated Monte Carlo method was developed to expedite the dose calculation for mesh-type computational phantoms.This involved designing and implementing the entire procedural flow of a GPUaccelerated Monte Carlo program.We employed acceleration structures to process the mesh-type phantom,optimized the traversal methodology,and achieved a flattened structure to overcome the limitations of GPU stack depths.Particle transport methods were realized within the mesh-type phantom,encompassing particle location and intersection techniques.In response to typical external irradiation scenarios,we utilized Geant4 along with the GPU program and its CPU serial code for dose calculations,assessing both computational accuracy and efficiency.In comparison with the benchmark simulated using Geant4 on the CPU using one thread,the relative differences in the organ dose calculated by the GPU program predominantly lay within a margin of 5%,whereas the computational time was reduced by a factor ranging from 120 to 2700.To the best of our knowledge,this study achieved a GPU-accelerated dose calculation method for mesh-type phantoms for the first time,reducing the computational time from hours to seconds per simulation of ten million particles and offering a swift and precise Monte Carlo method for dose calculation in mesh-type computational phantoms.
基金the National Key Research and Development Program of China(Grant No.2022YFB3404201)the National Natural Science Foundation of China(Grant Nos.52175335,52405342)+1 种基金the Natural Science Foundation Joint Foundation of Liaoning province(Grant No.2023-B SB A-108)the Fundamental Research Funds for the Central Universities(Grant No.N2402005)。
文摘The effects of the high pressure die casting(HPDC)processes on porosity,microstructure,and mechanical properties of heat-treatment-free aluminum silicon(Al-Si)alloys have long been a focal point in automotive die-casting research.In this work,the combined effect of shot sleeve materials and slow shot speeds on porosity,microstructure and mechanical properties of a newly designed HPDC Al-Si alloy was investigated.Results show that employing a ceramic shot sleeve or increasing the slow shot speed significantly reduces both the average size and area fraction of externally solidified crystals(ESCs),as well as the average pore size and volume fraction.When the slow shot speed is increased from 0.05 m·s^(-1)to 0.1 m·s^(-1),the pore volume fraction decreases by 10.2%in steel-shot-sleeve samples,compared to a substantial 67.1%reduction in ceramic-shot-sleeve samples.At a slow shot speed of 0.1 m·s^(-1),castings produced with a ceramic shot sleeve exhibit superior mechanical properties:8.3%higher yield strength,17.4%greater tensile strength,and an 81.4%improvement in elongation,relative to those from a steel shot sleeve.These findings provide valuable insights for minimizing porosity and coarse ESCs in die castings,offering promising potential for broader industrial applications.
基金supported by the National Natural Science Foundation of China (NSFC,Nos.12474274,92161101)the Innovation Project of Jinan Science and Technology Bureau(No.2021GXRC032)the Natural Science Foundation of Shandong Province (No.ZR2024MA091)。
文摘Traditional strategies for designing hyperhalogens,superatoms with exceptional electron-withdrawing capacity,rely on complex superhalogen assembly,posing significant experimental challenges.Here,we introduce a non-invasive dual external field(DEF) approach combining solvent effects and an oriented external electric field(OEEF) to construct hyperhalogens,as demonstrated by density functional theory(DFT) calculations.Our DEF strategy proves versatile,successfully designing hyperhalogens not only in simplified Ag_n^(-) model systems but also in the experimentally synthesized Ag_(25) nanocluster.Using the 3D Ag_(19)^(-) structure as a model,we further reveal the DEF's pivotal role in O_(2) activation,where solvent-OEEF synergy induces tunable O-O bond elongation and charge transfer,proportional to field strength.Our findings establish a field-driven paradigm for hyperhalogen design that preserves native cluster composition,providing a theoretical foundation for tailoring high-performance catalysts through precise activesite modulation.
基金Supported by the National Defense Basic Scientific Research Program of China.
文摘Amphibious vehicles are more prone to attitude instability compared to ships,making it crucial to develop effective methods for monitoring instability risks.However,large inclination events,which can lead to instability,occur frequently in both experimental and operational data.This infrequency causes events to be overlooked by existing prediction models,which lack the precision to accurately predict inclination attitudes in amphibious vehicles.To address this gap in predicting attitudes near extreme inclination points,this study introduces a novel loss function,termed generalized extreme value loss.Subsequently,a deep learning model for improved waterborne attitude prediction,termed iInformer,was developed using a Transformer-based approach.During the embedding phase,a text prototype is created based on the vehicle’s operation log data is constructed to help the model better understand the vehicle’s operating environment.Data segmentation techniques are used to highlight local data variation features.Furthermore,to mitigate issues related to poor convergence and slow training speeds caused by the extreme value loss function,a teacher forcing mechanism is integrated into the model,enhancing its convergence capabilities.Experimental results validate the effectiveness of the proposed method,demonstrating its ability to handle data imbalance challenges.Specifically,the model achieves over a 60%improvement in root mean square error under extreme value conditions,with significant improvements observed across additional metrics.
基金supported by the National Natural Science Foundation of China(No.52474396 and 52175284)the National Key Research and Development Program of China(Grant No.2022YFB3404201)。
文摘In order to investigate the effect of die wall thickness on morphologies of defect band,a stepped mold with a wall thickness of 5 mm,4 mm,3 mm,2 mm,and 1 mm was designed to carry out high pressure die casting experiments with AlSi10 MgMn alloy.For castings with wall thickness of 2-4 mm,the ratio of the mean defect band width(w)and mean grain size(d)in the defect band(w/d)ranges 7-18,while it increases to 24.47 for the 5 mm-thick casting.This difference is related with the filling speed and the distribution of externally solidified crystals(ESCs).The mold flow analysis indicates that the filling speed decreases from 25.41 m·s^(-1)to 11.07 m·s^(-1)when wall thickness increases from 2 mm to 5 mm.Due to the decreasing filling speed along the wall thickness,ESCs gradually diffuse from the center to the defect band,which keep the shear strength in the defect band at a high-level during filling.Meanwhile,the shear strength generated during the filling also decreases as the shear rate drops.Finally,the defect bands in the 5 mm-thick region become widen and indistinct,and the porosity is as high as 5.25%.
基金supported by the National Natural Science Foundation of China (NSFC 52175352)。
文摘Electroslag remelting(ESR) is an important metallurgical process for producing high-purity materials with homogeneous compositions and sound microstructures,and its typical products are ingots or simple castings.The core principle involves the resistive melting of a consumable electrode within a slag pool,followed by the refining of molten metal droplets as they traverse the slag,and subsequent sequential solidification in a water-cooled mold.However,conventional ESR processes face limitations in producing large or complex-shaped components,enhancing production efficiency,achieving highly specialized microstructures,and meeting ultra-high purity demands for advanced applications.Advanced composite ESR technologies have been developed to overcome these limitations by innovatively modifying key process aspects.For instance,electrode systems are improved using vibration,rotation,or multiple electrodes.Enhanced mold design and solidification control are achieved through techniques including conductive molds,mold rotation,and ingot withdrawal.Precise control of the process is realized through the use of protective gas,vacuum,or elevated pressure,as well as the application of external fields such as magnetic fields or ultrasonic vibration.This review comprehensively summarizes these advanced techniques,examining their principles and characteristics,and discussing their specific advantages and challenges.
文摘Objective:To understand the current awareness and willingness to learn about the use of out-of-hospital automated external defibrillators(AEDs)in Deyang City,providing a basis for improving the success rate of rescue operations.Methods:A questionnaire survey was conducted among residents in Deyang City from January 2025 to October 2025,covering residents’basic information,awareness of AED-related knowledge,and attitudes towards AED usage.Results:A total of 1,886 questionnaires were collected,with 1,823 valid questionnaires,yielding an effective rate of 96.66%.Among the 1,823 respondents,692(37.96%)had received cardiopulmonary resuscitation(CPR)-related learning or training,619(33.96%)could accurately describe the name of an AED,417(22.87%)could clearly describe the function of an AED,and 308(16.89%)could accurately describe how to use an AED.Among them,1,549(84.97%)were willing to provide assistance to patients experiencing cardiac arrest;1,731(94.95%)were willing to provide assistance under the premise of knowing how to use an AED;and 1,750(95.99%)were willing to learn about AED-related knowledge.Among the 91 individuals unwilling to provide rescue,75 responded with reasons.Among them,36 cases(48.00%)were reluctant to rescue due to a lack of relevant first aid knowledge,32 cases(42.67%)expressed concerns about exacerbating the patient’s condition due to improper operation,and 4 cases(5.33%)were unwilling to interact with strangers due to personal reasons.Conclusion:Currently,residents in Deyang City have limited knowledge about AEDs but demonstrate a strong willingness to learn and apply them.Measures need to be taken to enhance their understanding and application of AEDs.
文摘This paper examines the relationship between the Samuelson rule for efficient provision of stock externality and unilateral transfers for equalization of mitigation costs among the agents. Using a generic model of stock externality provisions, we proved that the revised Samuelson rule that allows transfers is a necessary and sufficient condition for efficient provision of stock externalities. In addition, selection of social welfare weights of the agents plays a key role in directions and magnitudes of the transfers. We discuss the implications of the revised Samuelson rule in economic modeling of climate change, an empirical case of stock externality, through numerical simulations in the RICE model.
基金financially supported by the Key Research and Development Program of Ningbo(Grant No.2023Z098)Natural Science Foundation of Inner Mongolia(Grant No.2023MS05040)+1 种基金Shenyang Collaborative Innovation Center Project for Multiple Energy Fields Composite Processing of Special Materials(Grant No.JG210027)Shenyang Key Technology Special Project of The Open Competition Mechanism to Select the Best Solution(Grant Nos.2022210101000827,2022-0-43-048).
文摘Titanium alloy has the advantages of high strength,strong corrosion resistance,excellent high and low temperature mechanical properties,etc.,and is widely used in aerospace,shipbuilding,weapons and equipment,and other fields.In recent years,with the continuous increase in demand for medium-thick plate titanium alloys,corresponding welding technologies have also continued to develop.Therefore,this article reviews the research progress of deep penetration welding technology for medium-thick plate titanium alloys,mainly covering traditional arc welding,high-energy beam welding,and other welding technologies.Among many methods,narrow gap welding,hybrid welding,and external energy field assistance welding all contribute to improving the welding efficiency and quality of medium-thick plate titanium alloys.Finally,the development trend of deep penetration welding technology for mediumthick plate titanium alloys is prospected.
基金financially supported by the National Key Re-search and Development Program of China(No.2023YFB4603301)Science Center for Gas Turbine Project(No.P2022-C-Ⅳ-002-001)+3 种基金National Natural Science Foundation of China(No.52401066)IMR Innovation Fund(No.2024-PY10)Project of TaiHang Laboratory(A3023)China Postdoctoral Science Foundation(No.2022M723211).
文摘Additive manufacturing(AM)technology has demonstrated significant potential in the green,lightweight,and functional development of metal materials,offering greater freedom and flexibility in the manufacturing process.However,the microstructural heterogeneity and mechanical property anisotropy of nickel-based superalloys along the build direction,stemming from thermal cycling,limit their widespread application in the aerospace industry.The proposed hybrid manufacturing process introduces external energy fields(thermal,ultrasonic,magnetic fields)into the forming processes,offering an innovative pathway to overcome the limitations of AM superalloys.This paper systematically discusses the influence of energy fields on the AM process of nickel-based superalloys,focusing on key issues such as cracking,porosity,microstructural heterogeneity,and mechanical property.Various energy fields modulate the melt pool dynamics and solidification process through distinct mechanisms.However,there remain several unresolved challenges and controversies regarding their mechanisms,particularly concerning the microstructural evolution under the synergistic effects of multiple energy fields.To address this issue,current studies predominantly focus on experimental validation,with a lack of unified theoretical models and numerical simulations,which limits the further development of energy field optimization strategies.Accordingly,the roles and advantages of various energy fields in AM of nickel-based superalloys are summarized.And engineering challenges are highlighted,such as multi-field synergistic control strategies,quantitative prediction models for microstructure-property,and energy field optimization methods for practical applications.Finally,the future trends of energy field-assisted AM for high-performance superalloys are discussed,with an outlook on its potential applications in re-manufacturing technologies and integrated equipment.
基金financially supported by the Key Research and Development Program of Shandong Province(Grant Nos.2022CXGC020405,2023CXGC010415 and 2025TSGCCZZB0238)the National Natural Science Foundation of China(Grant No.52171288)the financial support from CNPq,FAPERJ,ANP,Embrapii,and China National Petroleum Corporation(CNPC).
文摘This work investigated the dynamic behavior of vertical pipes conveying gas-liquid two-phase flow when subjected to external excitations at both ends.Even with minimal excitation amplitude,resonance can occur when the excitation frequency aligns with the natural frequency of the pipe,significantly increasing the degree of operational risk.The governing equation of motion based on the Euler-Bernoulli beam is derived for the relative deflection with stationary simply supported ends,with the effects of the external excitations represented by source terms distributed along the pipe length.The fourth-order partial differential equation is solved via the generalized integral transform technique(GITT),with the solution successfully verified via comparison with results in the literature.A comprehensive analysis of the vibration phenomena and changes in the motion state of the pipe is conducted for three classes of external excitation conditions:same frequency and amplitude(SFSA),same frequency but different amplitudes(SFDA),and different frequencies and amplitudes(DFDA).The numerical results show that with increasing gas volume fraction,the position corresponding to the maximum vibration displacement shifts upward.Compared with conditions without external excitation,the vibration displacement of the pipe conveying two-phase flow under external excitation increases significantly.The frequency of external excitation has a significant effect on the dynamic behavior of a pipe conveying two-phase flow.
基金supported by Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(No.SML2023SP243)the National Key Research and Development Program of China(No.2022YFC2906100)the National Natural Science Foundation of China(No.92475202)are acknowledged.
文摘Electrochemical metallurgy at low temperature(<473 K)shows promise for the extraction and refinement of metals and alloys in a green and sustainable manner.However,the kinetics of the electrodeposition process is generally slow at low temperature,resulting in large overpotential and low current efficiency.Thus,the application of external physical fields has emerged as an effective strategy for improving the mass and charge transfer processes during electrochemical reactions.This review highlights the challenges associated with low-temperature electrochemical processes and briefly discusses recent achievements in optimizing electrodeposition processes through the use of external physical fields.The regulating effects on the optimization of the electrodeposition process and the strategies for select-ing various external physical fields,including magnetic,supergravity,and ultrasonic fields are summarized from the perspectives of equipment and mechanisms.Finally,advanced methods for in-situ characterization of external physical field-assisted electrodeposition processes are reviewed to gain a deeper understanding of metallic electrodeposition.An in-depth exploration of the mechanism by which external physical fields affect the electrode process is essential for enhancing the efficiency of metal extraction at low temperatures.
文摘Bcakground: Pancreatic pseudocyst (PPC) is a common complication arising from acute or chronic pancreatitis, trauma, or pancreatic duct obstruction. When acute fluid collection persists for 4 - 6 weeks and is encapsulated by a fibrous wall, it is classified as a pancreatic pseudocyst. While PPC is generally asymptomatic in many patients, it can manifest with persistent abdominal pain, dyspepsia, intra-cystic infection, and potentially lead to gastrointestinal obstruction in some cases. Although smaller PPCs may resolve spontaneously, larger PPCs tend to be refractory to absorption and often necessitate surgical intervention to prevent complications such as intracystic hemorrhage. Objective: To explore the efficacy of percutaneous catheterization with negative pressure in the treatment of large pancreatic pseudocysts. Methods: The cases of large pancreatic pseudocysts treated in our hospital from 2004 to 2022 were retrospectively collected, and the general condition, operation time, drainage time, feeding time, postoperative complications, hospital stay, cost and follow-up of the patients were analyzed. Results: A total of 132 patients with large pancreatic pseudocysts were collected. The average operation time was 32.4 ± 2.1 min;The retention time of the drainage tube was 30 ± 1.8 days in the percutaneous negative pressure drainage group;The postoperative feeding time was no fasting after local anesthesia drainage;Postoperative complications (bleeding, infection, pancreatic leakage, recurrence, anastomotic leakage, etc.): Two of the 132 patients had recurrent cysts, which were cured by re-puncture and negative pressure drainage. The length of hospital stay was 6 ± 1.1 days;The cost was 11,200 ± 1300 yuan;Follow-up: The follow-up time ranged from 1 to 3 years, and the patients had no discomfort. Conclusion: Percutaneous catheterization and negative pressure drainage can effectively treat large pancreatic pseudocysts. Compared with other treatment methods, it is simple and effective, the postoperative recovery of patients is faster, the physical damage is less, the hospital stay is shorter, and the cost is lower.
