This paper presents a day-ahead optimal energy management strategy for economic operation of industrial microgrids with high-penetration renewables under both isolated and grid-connected operation modes.The approach i...This paper presents a day-ahead optimal energy management strategy for economic operation of industrial microgrids with high-penetration renewables under both isolated and grid-connected operation modes.The approach is based on a regrouping particle swarm optimization(RegPSO)formulated over a day-ahead scheduling horizon with one hour time step,taking into account forecasted renewable energy generations and electrical load demands.Besides satisfying its local energy demands,the microgrid considered in this paper(a real industrial microgrid,“Goldwind Smart Microgrid System”in Beijing,China),participates in energy trading with the main grid;it can either sell power to the main grid or buy from the main grid.Performance objectives include minimization of fuel cost,operation and maintenance costs and energy purchasing expenses from the main grid,and maximization of financial profit from energy selling revenues to the main grid.Simulation results demonstrate the effectiveness of various aspects of the proposed strategy in different scenarios.To validate the performance of the proposed strategy,obtained results are compared to a genetic algorithm(GA)based reference energy management approach and confirmed that the RegPSO based strategy was able to find a global optimal solution in considerably less computation time than the GA based reference approach.展开更多
Sustainable and resilient pavement infrastructure is critical for current economic and environmental challenges.In the past 10 years,the pavement infrastructure strongly supports the rapid development of the global so...Sustainable and resilient pavement infrastructure is critical for current economic and environmental challenges.In the past 10 years,the pavement infrastructure strongly supports the rapid development of the global social economy.New theories,new methods,new technologies and new materials related to pavement engineering are emerging.Deterioration of pavement infrastructure is a typical multi-physics problem.Because of actual coupled behaviors of traffic and environmental conditions,predictions of pavement service life become more and more complicated and require a deep knowledge of pavement material analysis.In order to summarize the current and determine the future research of pavement engineering,Journal of Traffic and Transportation Engineering(English Edition)has launched a review paper on the topic of"New innovations in pavement materials and engineering:A review on pavement engineering research 2021".Based on the joint-effort of 43 scholars from 24 well-known universities in highway engineering,this review paper systematically analyzes the research status and future development direction of 5 major fields of pavement engineering in the world.The content includes asphalt binder performance and modeling,mixture performance and modeling of pavement materials,multi-scale mechanics,green and sustainable pavement,and intelligent pavement.Overall,this review paper is able to provide references and insights for researchers and engineers in the field of pavement engineering.展开更多
Colorectal anastomotic leakage(CAL) remains a major complication after colorectal surgery. Despite all efforts during the last decades, the incidence of CAL has not decreased. In this review, we summarize the availabl...Colorectal anastomotic leakage(CAL) remains a major complication after colorectal surgery. Despite all efforts during the last decades, the incidence of CAL has not decreased. In this review, we summarize the available strategies regarding prevention, prediction and intervention of CAL and categorize them into three categories: communication, infection and healing disturbances. These three major factors actively interact during the onset of CAL. We aim to provide an integrated approach to CAL based on its etiology. The intraoperative air leak test, intraoperative endoscopy, radiological examinations and stoma construction mainly aim to detect and to prevent communication between the intra- and extra-luminal content. Other strategies including postoperative drainage, antibiotics, and infectious-parameter evaluation are intended to detect and prevent anastomotic or peritoneal infection. Most currently available interventions for CAL focus on the control of communication and infection, while strategies targeting the healing disturbances such as lifestyle changes, oxygen therapy and evaluation of metabolic biomarkers still lack wide clinical application. This simplified categorization may contribute to an integrated understanding of CAL. We strongly believe that this integrated approach should be taken into consideration during clinical practice. An integrated approach to CAL could contribute to a better understanding of the etiology of CAL and eventually better patient outcome.展开更多
Hepatitis E virus(HEV)infection can cause severe complications and high mortality,particularly in pregnant women,organ transplant recipients,individuals with pre-existing liver disease and immunosuppressed patients.Ho...Hepatitis E virus(HEV)infection can cause severe complications and high mortality,particularly in pregnant women,organ transplant recipients,individuals with pre-existing liver disease and immunosuppressed patients.However,there are still unmet needs for treating chronic HEV infections.Herein,we screened a best-in-class drug repurposing library consisting of 262 drugs/compounds.Upon screening,we identified vidofludimus calcium and pyrazofurin as novel anti-HEV entities.Vidofludimus calcium is the next-generation dihydroorotate dehydrogenase(DHODH)inhibitor in the phase 3 pipeline to treat autoimmune diseases or SARS-CoV-2 infection.Pyrazofurin selectively targets uridine monophosphate synthetase(UMPS).Their anti-HEV effects were further investigated in a range of cell culture models and human liver organoids models with wild type HEV strains and ribavirin treatment failure-associated HEV strains.Encouragingly,both drugs exhibited a sizeable therapeutic window against HEV.For instance,the IC50 value of vidofludimus calcium is 4.6–7.6-fold lower than the current therapeutic doses in patients.Mechanistically,their anti-HEV mode of action depends on the blockage of pyrimidine synthesis.Notably,two drugs robustly inhibited ribavirin treatment failure-associated HEV mutants(Y1320H,G1634R).Their combination with IFN-αresulted in synergistic antiviral activity.In conclusion,we identified vidofludimus calcium and pyrazofurin as potent candidates for the treatment of HEV infections.Based on their antiviral potency,and also the favorable safety profile identified in clinical studies,our study supports the initiation of clinical studies to repurpose these drugs for treating chronic hepatitis E.展开更多
This study presents a hybrid data-mining framework based on feature selection algorithms and clustering methods to perform the pattern discovery of high-speed railway train rescheduling strategies(RSs).The proposed mo...This study presents a hybrid data-mining framework based on feature selection algorithms and clustering methods to perform the pattern discovery of high-speed railway train rescheduling strategies(RSs).The proposed model is composed of two states.In the first state,decision tree,random forest,gradient boosting decision tree(GBDT)and extreme gradient boosting(XGBoost)models are used to investigate the importance of features.The features that have a high influence on RSs are first selected.In the second state,a K-means clustering method is used to uncover the interdependences between RSs and the influencing features,based on the results in the first state.The proposed method can determine the quantitative relationships between RSs and influencing factors.The results clearly show the influences of the factors on RSs,the possibilities of different train operation RSs under different situations,as well as some key time periods and key trains that the controllers should pay more attention to.The research in this paper can help train traffic controllers better understand the train operation patterns and provides direction for optimizing rail traffic RSs.展开更多
In 2017,a ballistic phenomenological model was proposed by the authors of Ref.[1] to numerically simulate the experimental depths of small caliber projectiles impacting walls made of adobe.The opportunity for a new mo...In 2017,a ballistic phenomenological model was proposed by the authors of Ref.[1] to numerically simulate the experimental depths of small caliber projectiles impacting walls made of adobe.The opportunity for a new model in the field revealed from the observation that two older models recently used by the authors of Ref.[2] shared a linear relationship between the penetration depth P and the impacting velocity v_(O).展开更多
The biokinetics of Cu in Daphnia magna, including dissolved uptake, assimilation and efflux, has been determined using a gamma 67^Cu radiotracer methodology. However, this gamma emitting radioisotope is not readily av...The biokinetics of Cu in Daphnia magna, including dissolved uptake, assimilation and efflux, has been determined using a gamma 67^Cu radiotracer methodology. However, this gamma emitting radioisotope is not readily available due to its very short half-life. In the present study, we employed a stable isotope tracer （65^Cu） to determine the Cu biokinetics and compared our results to those determined using 67^Cu. The dissolved uptake rate constant of 65^Cu was 3.36 L/（g.day）, which is higher than that of 67^Cu （1.32 L/（g.day））. With increasing food concentrations from 2×10^4 to 1×10^5 cells/mL, the Cu assimilation efficiency （AE） decreased from 46% to 11%, compared to a decrease from 27% to 16% when determined using 67^Cu. The effiux of Cu from Daphnia magna was quantified following both dissolved and dietary uptake. The efflux of waterborne Cu was comparable to that of dietborne Cu and the effiux rate constant （0.32-0.52 day^-l） was higher than that determined by 67^Cu （0.19-0.20 day^-1）. By considering different water properties and handling procedure between the two experiments, we believe that these differences are reasonable. Overall, this study demonstrated that the enriched stable isotope tracer technique is a powerful tool to investigate metal bioavailability and maybe a good alternative to radioactive measurements.展开更多
Recently, researchers in the road field are focusing on the development of green asphalt materials with loweremission of volatile organic compounds (VOCs). The characterization methodology of asphalt VOCs and theinflu...Recently, researchers in the road field are focusing on the development of green asphalt materials with loweremission of volatile organic compounds (VOCs). The characterization methodology of asphalt VOCs and theinfluencing factors on VOCs release have always been the basic issue of asphalt VOCs emission reduction research.Researchers have proposed a variety of asphalt VOCs characterization methodologies, which also have mutuallyirreplaceable characteristics. Asphalt VOCs volatilization is affected by many factors. In this study, asphalt VOCscharacterization methodologies were summarized, including their advantages, disadvantages, characteristics andapplicable requirements. Subsequently, the influencing factors of VOCs release, such as asphalt types and environment conditions, are summarized to provide theoretical support for the emission reduction research. Theclassification and mechanism of newly-development asphalt VOCs emission reduction materials are reviewed. Thereduction efficiencies are also compared to select better materials and put forward the improvement objective ofnew materials and new processes. In addition, the prospects about development of VOCs release mechanism ofasphalt materials during the full life cycle and feasibility research of high-efficiency composite emission reductionmaterials in the future were put forward.展开更多
Fracture network connectivity and aperture （or conductivity） distribution are two crucial features controlling flow behavior of naturally fractured reservoirs. The effect of connectivity on flow properties is well d...Fracture network connectivity and aperture （or conductivity） distribution are two crucial features controlling flow behavior of naturally fractured reservoirs. The effect of connectivity on flow properties is well documented. In this paper, however, we focus here on the influence of fracture aperture distribution. We model a two dimensional fractured reservoir in which the matrix is impermeable and the fractures are well connected. The fractures obey a power-law length distribution, as observed in natural fracture networks. For the aperture distribution, since the information from subsurface fracture networks is limited, we test a number of cases： log-normal distributions （from narrow to broad）, power-law distributions （from narrow to broad）, and one case where the aperture is pro- portional to the fracture length. We find that even a well- connected fracture network can behave like a much sparser network when the aperture distribution is broad enough （c~ 〈 2 for power-law aperture distributions and σ ≥ 0.4 for log-normal aperture distributions）. Specifically, most fractures can be eliminated leaving the remaining dominant sub-network with 90% of the permeability of the original fracture network. We determine how broad the aperture distribution must be to approach this behavior and the dependence of the dominant sub-network on the parameters of the aperture distribution. We also explore whether one can identify the dominant sub-network without doing flow calculations.展开更多
Short pitch corrugation has been a problem for railways worldwide over one century.In this paper,a parametric investigation of fastenings is conducted to understand the corrugation formation mechanism and gain insight...Short pitch corrugation has been a problem for railways worldwide over one century.In this paper,a parametric investigation of fastenings is conducted to understand the corrugation formation mechanism and gain insights into corrugation mitigation.A three-dimensional finite element vehicle-track dynamic interaction model is employed,which considers the coupling between the structural dynamics and the contact mechanics,while the damage mechanism is assumed to be differential wear.Various fastening models with different configurations,boundary conditions,and parameters of stiffness and damping are built up and analysed.These models may represent different service stages of fastenings in the field.Besides,the effect of train speeds on corrugation features is studied.The results indicate:(1)Fastening parameters and modelling play an important role in corrugation formation.(2)The fastening longitudinal constraint to the rail is the major factor that determines the corrugation formation.The fastening vertical and lateral constraints influence corrugation features in terms of spatial distribution and wavelength components.(3)The strengthening of fastening constraints in the longitudinal dimension helps to mitigate corrugation.Meanwhile,the inner fastening constraint in the lateral direction is necessary for corrugation alleviation.(4)The increase in fastening longitudinal stiffness and damping can reduce the vibration amplitudes of longitudinal compression modes and thus reduce the track corrugation propensity.The simulation in this work can well explain the field corrugation in terms of the occurrence possibility and major wavelength components.It can also explain the field data with respect to the small variation between the corrugation wavelength and train speed,which is caused by frequency selection and jump between rail longitudinal compression modes.展开更多
Foam is utilized in enhanced oil recovery and CO_(2) sequestration.Surfactant-alternating-gas(SAG)is a preferred approach for placing foam into reservoirs,due to it enhances gas injection and minimizes corrosion in fa...Foam is utilized in enhanced oil recovery and CO_(2) sequestration.Surfactant-alternating-gas(SAG)is a preferred approach for placing foam into reservoirs,due to it enhances gas injection and minimizes corrosion in facilities.Our previous studies with similar permeability cores show that during SAG injection,several banks occupy the area near the well where fluid exhibits distinct behaviour.However,underground reservoirs are heterogeneous,often layered.It is crucial to understand the effect of permeability on fluid behaviour and injectivity in a SAG process.In this work,coreflood experiments are conducted in cores with permeabilities ranging from 16 to 2300 mD.We observe the same sequence of banks in cores with different permeabilities.However,the speed at which banks propagate and their overall mobility can vary depending on permeability.At higher permeabilities,the gas-dissolution bank and the forced-imbibition bank progress more rapidly during liquid injection.The total mobilities of both banks decrease with permeability.By utilizing a bank-propagation model,we scale up our experimental findings and compare them to results obtained using the Peaceman equation.Our findings reveal that the liquid injectivity in a SAG foam process is misestimated by conventional simulators based on the Peaceman equation.The lower the formation permeability,the greater the error.展开更多
The combination of high efficiency and environmental stability is vital to promote the commercial appli-cations of microwave absorption(MA)materials,yet remains challenging in the absence of facile routes.Here,we put ...The combination of high efficiency and environmental stability is vital to promote the commercial appli-cations of microwave absorption(MA)materials,yet remains challenging in the absence of facile routes.Here,we put forward a graphene-reinforced construct approach for one-pot synthesis of 3D intercon-nected magnetic-dielectric frameworks via pre-functionalization and subsequent assembly.Multiple in-teractions among discrete precursors are capable of manipulating the confined growth and interfacial self-assembly.Significant enhancements in MA properties are triggered in a straightforward manner us-ing ultralow feeding fractions of graphene oxide nanosheet.The minimum reflection loss is up to-60.1 dB(99.9999%wave absorption)and the effective absorption bandwidth reaches 5.9 GHz(almost covering the Ku band).Remarkably,based on the optimization by ultralow concentrations of graphene,the as-prepared nanoarchitecture simultaneously integrates strong absorption,broad bandwidth,and low matching thick-ness.The embedded graphene nanosheets serve as high-speed electron transmission channels and hollow resonance cavities,facilitating multimode attenuations and impedance-matching characteristics.Mean-while,the graphene-reinforced framework suppresses the corrosion of magnetic components,whose cor-rosion rate reduces by an order of magnitude.This study provides a simple procedure to boost magnetic-dielectric absorbers for comprehensive MA performances and enhanced corrosion resistance.展开更多
Tribological interactions between surgical suture and human tissue play an important role in the stitching process.The purpose of the paper is to understanding the tribological behavior of surgical suture interacting ...Tribological interactions between surgical suture and human tissue play an important role in the stitching process.The purpose of the paper is to understanding the tribological behavior of surgical suture interacting with artificial skin,with respect to surgical suture material and structure,by means of a capstan experiment approach and a contact area model.The results indicated that structure and surface topography of the surgical suture had a pronounced effect on the tribological interactions.The apparent coefficient of friction of vicryl surgical suture was the smallest among the three surgical suture materials.As the sliding velocity increased,or the applied load decreased,the coefficient of friction increased.Furthermore,stick-slip phenomena were observed during the sliding procedure.展开更多
Monopiles are the most common foundation form of offshore wind turbines,which bear the vertical load,lateral load and bending moment.It remains uncertain whether the applied vertical load increases the lateral deflect...Monopiles are the most common foundation form of offshore wind turbines,which bear the vertical load,lateral load and bending moment.It remains uncertain whether the applied vertical load increases the lateral deflection of the pile.This paper investigated the influence of vertical load on the behaviour of monopiles installed in the sand under combined load using three-dimensional numerical methods.The commercial software PLAXIS was used for simulations in this paper.Monopiles were modelled as a structure incorporating linear elastic material behaviour and soil was modelled using the Hardening-Soil(HS)constitutive model.The monopiles under vertical load,lateral load and combined vertical and lateral loads were respectively studied taking into account the sequence of load application and pile slenderness ratio(L/D;L and D are the length and diameter of the pile).Results suggest that the sequence of load application plays a major role in how vertical load affects the deflection behaviour of the pile.Specifically,when L/D ratios obtained by lengthening the pile while keeping its diameter constant are 3,5 and 8,the relationships between lateral load and the deflection behaviour of the pile under the effect of vertical load demonstrate a similar trend.Furthermore,the cause of increased lateral capacity of the pile under the action of applied vertical load in the common practical application case and in the VPL case was analyzed by studying the variation law of soil stress along the pile embedment.Results confirm that the confining effect of vertical load increases means effective stress of the soil around the pile,thus increasing soil stiffness and pile capacity.展开更多
文摘This paper presents a day-ahead optimal energy management strategy for economic operation of industrial microgrids with high-penetration renewables under both isolated and grid-connected operation modes.The approach is based on a regrouping particle swarm optimization(RegPSO)formulated over a day-ahead scheduling horizon with one hour time step,taking into account forecasted renewable energy generations and electrical load demands.Besides satisfying its local energy demands,the microgrid considered in this paper(a real industrial microgrid,“Goldwind Smart Microgrid System”in Beijing,China),participates in energy trading with the main grid;it can either sell power to the main grid or buy from the main grid.Performance objectives include minimization of fuel cost,operation and maintenance costs and energy purchasing expenses from the main grid,and maximization of financial profit from energy selling revenues to the main grid.Simulation results demonstrate the effectiveness of various aspects of the proposed strategy in different scenarios.To validate the performance of the proposed strategy,obtained results are compared to a genetic algorithm(GA)based reference energy management approach and confirmed that the RegPSO based strategy was able to find a global optimal solution in considerably less computation time than the GA based reference approach.
基金National Key R&D Program of China(No.2018YFB1600200,2021YFB1600200)National Natural Science Foundation of China(No.51608457,51778038,51808016,51808403,51908057,51908072,51908165,51908331,52008029,52008069,52078018,52078025,52078049,52078209,52108403,52122809,52178417)+9 种基金Marie Sk?odowska-Curie Individual Fellowships of the European Commission’s Horizon 2020 programme(No.101024139)Natural Science Foundation of Heilongjiang Province(No.JJ2020ZD0015)China Postdoctoral Science Foundation funded project(No.BX20180088)Research Capability Enhancement Program for Young Professors of Beijing University of Civil Engineering and Architecture(No.02080921021)Young Scholars of Beijing Talent Program(No.02082721009)Beijing Municipal Natural Science Foundation and Beijing Municipal Education Commission(No.KZ201910016017)German Research Foundation(No.OE 514/15-1(459436571))Fundamental Research Funds for the Central Universities(No.2020kfyXJJS127)Marie Sk?odowska-Curie Individual Fellowships of the European Commission’s Horizon 2020 Programme(No.101030767)Research Fund for High Level Talent Program(No.22120210108)。
文摘Sustainable and resilient pavement infrastructure is critical for current economic and environmental challenges.In the past 10 years,the pavement infrastructure strongly supports the rapid development of the global social economy.New theories,new methods,new technologies and new materials related to pavement engineering are emerging.Deterioration of pavement infrastructure is a typical multi-physics problem.Because of actual coupled behaviors of traffic and environmental conditions,predictions of pavement service life become more and more complicated and require a deep knowledge of pavement material analysis.In order to summarize the current and determine the future research of pavement engineering,Journal of Traffic and Transportation Engineering(English Edition)has launched a review paper on the topic of"New innovations in pavement materials and engineering:A review on pavement engineering research 2021".Based on the joint-effort of 43 scholars from 24 well-known universities in highway engineering,this review paper systematically analyzes the research status and future development direction of 5 major fields of pavement engineering in the world.The content includes asphalt binder performance and modeling,mixture performance and modeling of pavement materials,multi-scale mechanics,green and sustainable pavement,and intelligent pavement.Overall,this review paper is able to provide references and insights for researchers and engineers in the field of pavement engineering.
文摘Colorectal anastomotic leakage(CAL) remains a major complication after colorectal surgery. Despite all efforts during the last decades, the incidence of CAL has not decreased. In this review, we summarize the available strategies regarding prevention, prediction and intervention of CAL and categorize them into three categories: communication, infection and healing disturbances. These three major factors actively interact during the onset of CAL. We aim to provide an integrated approach to CAL based on its etiology. The intraoperative air leak test, intraoperative endoscopy, radiological examinations and stoma construction mainly aim to detect and to prevent communication between the intra- and extra-luminal content. Other strategies including postoperative drainage, antibiotics, and infectious-parameter evaluation are intended to detect and prevent anastomotic or peritoneal infection. Most currently available interventions for CAL focus on the control of communication and infection, while strategies targeting the healing disturbances such as lifestyle changes, oxygen therapy and evaluation of metabolic biomarkers still lack wide clinical application. This simplified categorization may contribute to an integrated understanding of CAL. We strongly believe that this integrated approach should be taken into consideration during clinical practice. An integrated approach to CAL could contribute to a better understanding of the etiology of CAL and eventually better patient outcome.
基金funded by the National Natural Science Foundation of China(32270161,32100117,32100118)the Natural Science Foundation of Jiangsu Province of China(BK20210899,BK20210900,BK20210901)+1 种基金Research Grant of Jiangsu Commission of Health,China(ZD2021036)the Starting Grant for Talents of Xuzhou Medical University(D2021007,D2021008).
文摘Hepatitis E virus(HEV)infection can cause severe complications and high mortality,particularly in pregnant women,organ transplant recipients,individuals with pre-existing liver disease and immunosuppressed patients.However,there are still unmet needs for treating chronic HEV infections.Herein,we screened a best-in-class drug repurposing library consisting of 262 drugs/compounds.Upon screening,we identified vidofludimus calcium and pyrazofurin as novel anti-HEV entities.Vidofludimus calcium is the next-generation dihydroorotate dehydrogenase(DHODH)inhibitor in the phase 3 pipeline to treat autoimmune diseases or SARS-CoV-2 infection.Pyrazofurin selectively targets uridine monophosphate synthetase(UMPS).Their anti-HEV effects were further investigated in a range of cell culture models and human liver organoids models with wild type HEV strains and ribavirin treatment failure-associated HEV strains.Encouragingly,both drugs exhibited a sizeable therapeutic window against HEV.For instance,the IC50 value of vidofludimus calcium is 4.6–7.6-fold lower than the current therapeutic doses in patients.Mechanistically,their anti-HEV mode of action depends on the blockage of pyrimidine synthesis.Notably,two drugs robustly inhibited ribavirin treatment failure-associated HEV mutants(Y1320H,G1634R).Their combination with IFN-αresulted in synergistic antiviral activity.In conclusion,we identified vidofludimus calcium and pyrazofurin as potent candidates for the treatment of HEV infections.Based on their antiviral potency,and also the favorable safety profile identified in clinical studies,our study supports the initiation of clinical studies to repurpose these drugs for treating chronic hepatitis E.
基金This work was supported by the National Natural Science Foundation of China(Grant No.71871188)The authors also acknowledge the Open Fund of Hubei Key Laboratory of Power System Design and Test for Electrical Vehicle and the support of the State Key Laboratory of Rail Traffic Control(Grant No.RCS2019K007).Finally,the authors are grateful for the useful contributions made by their project partners.
文摘This study presents a hybrid data-mining framework based on feature selection algorithms and clustering methods to perform the pattern discovery of high-speed railway train rescheduling strategies(RSs).The proposed model is composed of two states.In the first state,decision tree,random forest,gradient boosting decision tree(GBDT)and extreme gradient boosting(XGBoost)models are used to investigate the importance of features.The features that have a high influence on RSs are first selected.In the second state,a K-means clustering method is used to uncover the interdependences between RSs and the influencing features,based on the results in the first state.The proposed method can determine the quantitative relationships between RSs and influencing factors.The results clearly show the influences of the factors on RSs,the possibilities of different train operation RSs under different situations,as well as some key time periods and key trains that the controllers should pay more attention to.The research in this paper can help train traffic controllers better understand the train operation patterns and provides direction for optimizing rail traffic RSs.
文摘In 2017,a ballistic phenomenological model was proposed by the authors of Ref.[1] to numerically simulate the experimental depths of small caliber projectiles impacting walls made of adobe.The opportunity for a new model in the field revealed from the observation that two older models recently used by the authors of Ref.[2] shared a linear relationship between the penetration depth P and the impacting velocity v_(O).
基金supported by the National Basic Research Program of China "Water Environmental Quality Evolution and Water Quality Criteria in Lakes" (No.2008CB418201)the National Natural Science Foundation of China (No. 40871215)the Natural Science Foundation of Beijing (No. 8092019)
文摘The biokinetics of Cu in Daphnia magna, including dissolved uptake, assimilation and efflux, has been determined using a gamma 67^Cu radiotracer methodology. However, this gamma emitting radioisotope is not readily available due to its very short half-life. In the present study, we employed a stable isotope tracer （65^Cu） to determine the Cu biokinetics and compared our results to those determined using 67^Cu. The dissolved uptake rate constant of 65^Cu was 3.36 L/（g.day）, which is higher than that of 67^Cu （1.32 L/（g.day））. With increasing food concentrations from 2×10^4 to 1×10^5 cells/mL, the Cu assimilation efficiency （AE） decreased from 46% to 11%, compared to a decrease from 27% to 16% when determined using 67^Cu. The effiux of Cu from Daphnia magna was quantified following both dissolved and dietary uptake. The efflux of waterborne Cu was comparable to that of dietborne Cu and the effiux rate constant （0.32-0.52 day^-l） was higher than that determined by 67^Cu （0.19-0.20 day^-1）. By considering different water properties and handling procedure between the two experiments, we believe that these differences are reasonable. Overall, this study demonstrated that the enriched stable isotope tracer technique is a powerful tool to investigate metal bioavailability and maybe a good alternative to radioactive measurements.
基金the National Natural Science Foundation of China(52378460 and 51878526)the Program Fund of Non-metallic Excellent and Innovation Center for Building Materials(Grants 2024TDA-3)Knowledge Innovation Program of Wuhan-Basic Research from the Wuhan Science and Technology Bureau(2022020801010176)are gratefully acknowledged.
文摘Recently, researchers in the road field are focusing on the development of green asphalt materials with loweremission of volatile organic compounds (VOCs). The characterization methodology of asphalt VOCs and theinfluencing factors on VOCs release have always been the basic issue of asphalt VOCs emission reduction research.Researchers have proposed a variety of asphalt VOCs characterization methodologies, which also have mutuallyirreplaceable characteristics. Asphalt VOCs volatilization is affected by many factors. In this study, asphalt VOCscharacterization methodologies were summarized, including their advantages, disadvantages, characteristics andapplicable requirements. Subsequently, the influencing factors of VOCs release, such as asphalt types and environment conditions, are summarized to provide theoretical support for the emission reduction research. Theclassification and mechanism of newly-development asphalt VOCs emission reduction materials are reviewed. Thereduction efficiencies are also compared to select better materials and put forward the improvement objective ofnew materials and new processes. In addition, the prospects about development of VOCs release mechanism ofasphalt materials during the full life cycle and feasibility research of high-efficiency composite emission reductionmaterials in the future were put forward.
文摘Fracture network connectivity and aperture （or conductivity） distribution are two crucial features controlling flow behavior of naturally fractured reservoirs. The effect of connectivity on flow properties is well documented. In this paper, however, we focus here on the influence of fracture aperture distribution. We model a two dimensional fractured reservoir in which the matrix is impermeable and the fractures are well connected. The fractures obey a power-law length distribution, as observed in natural fracture networks. For the aperture distribution, since the information from subsurface fracture networks is limited, we test a number of cases： log-normal distributions （from narrow to broad）, power-law distributions （from narrow to broad）, and one case where the aperture is pro- portional to the fracture length. We find that even a well- connected fracture network can behave like a much sparser network when the aperture distribution is broad enough （c~ 〈 2 for power-law aperture distributions and σ ≥ 0.4 for log-normal aperture distributions）. Specifically, most fractures can be eliminated leaving the remaining dominant sub-network with 90% of the permeability of the original fracture network. We determine how broad the aperture distribution must be to approach this behavior and the dependence of the dominant sub-network on the parameters of the aperture distribution. We also explore whether one can identify the dominant sub-network without doing flow calculations.
文摘Short pitch corrugation has been a problem for railways worldwide over one century.In this paper,a parametric investigation of fastenings is conducted to understand the corrugation formation mechanism and gain insights into corrugation mitigation.A three-dimensional finite element vehicle-track dynamic interaction model is employed,which considers the coupling between the structural dynamics and the contact mechanics,while the damage mechanism is assumed to be differential wear.Various fastening models with different configurations,boundary conditions,and parameters of stiffness and damping are built up and analysed.These models may represent different service stages of fastenings in the field.Besides,the effect of train speeds on corrugation features is studied.The results indicate:(1)Fastening parameters and modelling play an important role in corrugation formation.(2)The fastening longitudinal constraint to the rail is the major factor that determines the corrugation formation.The fastening vertical and lateral constraints influence corrugation features in terms of spatial distribution and wavelength components.(3)The strengthening of fastening constraints in the longitudinal dimension helps to mitigate corrugation.Meanwhile,the inner fastening constraint in the lateral direction is necessary for corrugation alleviation.(4)The increase in fastening longitudinal stiffness and damping can reduce the vibration amplitudes of longitudinal compression modes and thus reduce the track corrugation propensity.The simulation in this work can well explain the field corrugation in terms of the occurrence possibility and major wavelength components.It can also explain the field data with respect to the small variation between the corrugation wavelength and train speed,which is caused by frequency selection and jump between rail longitudinal compression modes.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.U2240210,52279098)the Natural Science Foundation of Jiangsu Province(Grant No.BK20200525)the Fundamental Research Funds for the Central Universities(Grant No.B230201021).We express our gratitude to PETRONAS and Shell Global Solution International B.V.for their support of this work.
文摘Foam is utilized in enhanced oil recovery and CO_(2) sequestration.Surfactant-alternating-gas(SAG)is a preferred approach for placing foam into reservoirs,due to it enhances gas injection and minimizes corrosion in facilities.Our previous studies with similar permeability cores show that during SAG injection,several banks occupy the area near the well where fluid exhibits distinct behaviour.However,underground reservoirs are heterogeneous,often layered.It is crucial to understand the effect of permeability on fluid behaviour and injectivity in a SAG process.In this work,coreflood experiments are conducted in cores with permeabilities ranging from 16 to 2300 mD.We observe the same sequence of banks in cores with different permeabilities.However,the speed at which banks propagate and their overall mobility can vary depending on permeability.At higher permeabilities,the gas-dissolution bank and the forced-imbibition bank progress more rapidly during liquid injection.The total mobilities of both banks decrease with permeability.By utilizing a bank-propagation model,we scale up our experimental findings and compare them to results obtained using the Peaceman equation.Our findings reveal that the liquid injectivity in a SAG foam process is misestimated by conventional simulators based on the Peaceman equation.The lower the formation permeability,the greater the error.
基金support from the National Natural Science Foundation of China(No.52073039)Major Special Projects of Sichuan Province(Nos.2019ZDZX0027 and 2019ZDZX0016).
文摘The combination of high efficiency and environmental stability is vital to promote the commercial appli-cations of microwave absorption(MA)materials,yet remains challenging in the absence of facile routes.Here,we put forward a graphene-reinforced construct approach for one-pot synthesis of 3D intercon-nected magnetic-dielectric frameworks via pre-functionalization and subsequent assembly.Multiple in-teractions among discrete precursors are capable of manipulating the confined growth and interfacial self-assembly.Significant enhancements in MA properties are triggered in a straightforward manner us-ing ultralow feeding fractions of graphene oxide nanosheet.The minimum reflection loss is up to-60.1 dB(99.9999%wave absorption)and the effective absorption bandwidth reaches 5.9 GHz(almost covering the Ku band).Remarkably,based on the optimization by ultralow concentrations of graphene,the as-prepared nanoarchitecture simultaneously integrates strong absorption,broad bandwidth,and low matching thick-ness.The embedded graphene nanosheets serve as high-speed electron transmission channels and hollow resonance cavities,facilitating multimode attenuations and impedance-matching characteristics.Mean-while,the graphene-reinforced framework suppresses the corrosion of magnetic components,whose cor-rosion rate reduces by an order of magnitude.This study provides a simple procedure to boost magnetic-dielectric absorbers for comprehensive MA performances and enhanced corrosion resistance.
文摘Tribological interactions between surgical suture and human tissue play an important role in the stitching process.The purpose of the paper is to understanding the tribological behavior of surgical suture interacting with artificial skin,with respect to surgical suture material and structure,by means of a capstan experiment approach and a contact area model.The results indicated that structure and surface topography of the surgical suture had a pronounced effect on the tribological interactions.The apparent coefficient of friction of vicryl surgical suture was the smallest among the three surgical suture materials.As the sliding velocity increased,or the applied load decreased,the coefficient of friction increased.Furthermore,stick-slip phenomena were observed during the sliding procedure.
文摘Monopiles are the most common foundation form of offshore wind turbines,which bear the vertical load,lateral load and bending moment.It remains uncertain whether the applied vertical load increases the lateral deflection of the pile.This paper investigated the influence of vertical load on the behaviour of monopiles installed in the sand under combined load using three-dimensional numerical methods.The commercial software PLAXIS was used for simulations in this paper.Monopiles were modelled as a structure incorporating linear elastic material behaviour and soil was modelled using the Hardening-Soil(HS)constitutive model.The monopiles under vertical load,lateral load and combined vertical and lateral loads were respectively studied taking into account the sequence of load application and pile slenderness ratio(L/D;L and D are the length and diameter of the pile).Results suggest that the sequence of load application plays a major role in how vertical load affects the deflection behaviour of the pile.Specifically,when L/D ratios obtained by lengthening the pile while keeping its diameter constant are 3,5 and 8,the relationships between lateral load and the deflection behaviour of the pile under the effect of vertical load demonstrate a similar trend.Furthermore,the cause of increased lateral capacity of the pile under the action of applied vertical load in the common practical application case and in the VPL case was analyzed by studying the variation law of soil stress along the pile embedment.Results confirm that the confining effect of vertical load increases means effective stress of the soil around the pile,thus increasing soil stiffness and pile capacity.
