The northwestern margin of Junggar Basin is the region with the richest oil sand resources in China.For better understanding the enrichment rules and deployment of exploration and development of regional oil sand,it i...The northwestern margin of Junggar Basin is the region with the richest oil sand resources in China.For better understanding the enrichment rules and deployment of exploration and development of regional oil sand,it is of great scientific significance to study the accumulation conditions of oil sand in different strata and mining areas of the Junggar Basin.Through a large number of field investigations,drilling verification and sampling tests,it is found that the oil sand in the region covers an area of 2000 km^(2),with shallow and thick reservoir,and predicted resource of 180 million tons.The oil sand resources are mainly distributed in four geological strata,namely the Middle Triassic Karamay Formation,Early Jurassic Badaowan Formation,Late Jurassic Qigu Formation,and Early Cretaceous Qingshuihe Formation.The reservoir is mainly composed of sandstone with high porosity and permeability,and the reservoir space is mainly intergranular pores with a medium average oil content.The oil sand deposit in the region is a typical destructive oil reservoir.The crude oil in the oil sand layer is degraded and thickened from the deep to the shallow,the content of saturated hydrocarbon decreased,and the content of aromatic hydrocarbon,non-hydrocarbon and asphaltene increased.The oil source comes from the deep Permian hydrocarbon-generating depression.Unconformities,faults and marginal fan delta-braided river depositional systems constitute effective migration and storage systems.Caprocks of the Upper Triassic Baijiantan Formation,Lower Jurassic Sangonghe Formation and Lower Cretaceous Hutubihe Formation were formed by three large scale lake transgressions.The Indosinian,Yanshan and Late Yanshan movements are the main driving forces for the migration of deep oil and gas to the shallow edge to form oil sand deposits.It is considered that the oil sand in the northwestern margin of Junggar Basin is of a slope complex migration type.展开更多
High-Altitude Long-Endurance(HALE)solar-powered Unmanned Aircraft Vehicles(UAVs)can utilize solar energy as power source and maintain extremely long cruise endurance,which has attracted extensive attentions from resea...High-Altitude Long-Endurance(HALE)solar-powered Unmanned Aircraft Vehicles(UAVs)can utilize solar energy as power source and maintain extremely long cruise endurance,which has attracted extensive attentions from researchers.Trajectory optimization is a promising way to achieve superior flight time because of the finite solar energy absorbed in a day.In this work,a method of trajectory optimization and guidance for HALE solar-powered aircraft based on a Reinforcement Learning(RL)framework is introduced.According to flight and environment information,a neural network controller outputs commands of thrust,attack angle,and bank angle to realize an autonomous flight based on energy maximization.The validity of the proposed method was evaluated in a 5-km radius area in simulation,and results have shown that after one day-night cycle,the battery energy of the RL-controller was improved by 31%and 17%compared with those of a Steady-State(SS)strategy with a constant speed and a constant altitude and a kind of statemachine strategy,respectively.In addition,results of an uninterrupted flight test have shown that the endurance of the RL controller was longer than those of the control cases.展开更多
Although industrial processes often perform perfectly under design conditions, they may deviate from the optimal operating point owing to parameters drift, environmental disturbances, etc. Thus, it is necessary to dev...Although industrial processes often perform perfectly under design conditions, they may deviate from the optimal operating point owing to parameters drift, environmental disturbances, etc. Thus, it is necessary to develop efficacious strategies or procedure to assess the process performance online. In this paper, we explore the issue of operating optimality assessment for complex industrial processes based on performance-similarity considering nonlinearities and outliers simultaneously, and a general enforced online performance assessment framework is proposed. In the offline part, a new and modified total robust kernel projection to latent structures algorithm,T-KPRM, is proposed and used to evaluate the complex nonlinear industrial process, which can effectively extract the optimal-index-related process variation information from process data and establish assessment models for each performance grades overcoming the effects of outlier. In the online part, the online assessment results can be obtained by calculating the similarity between the online data from a sliding window and each of the performance grades. Furthermore, in order to improve the accuracy of online assessment, we propose an online assessment strategy taking account of the effects of noise and process uncertainties. The Euclidean distance between the sliding data window and the optimal evaluation level is employed to measure the contribution rates of variables, which indicate the possible reason for the non-optimal operating performance. The proposed framework is tested on a real industrial case: dense medium coal preparation process, and the results shows the efficiency of the proposed method comparing to the existing method.展开更多
Response speed is vital for the railway environment monitoring system,especially for the sudden-onset disasters.The edge-cloud collaboration scheme is proved efficient to reduce the latency.However,the data characteri...Response speed is vital for the railway environment monitoring system,especially for the sudden-onset disasters.The edge-cloud collaboration scheme is proved efficient to reduce the latency.However,the data characteristics and communication demand of the tasks in the railway environment monitoring system are all different and changeable,and the latency contribution of each task to the system is discrepant.Hence,two valid latency minimization strategies based on the edge-cloud collaboration scheme is developed in this paper.First,the processing resources are allocated to the tasks based on the priorities,and the tasks are processed parallly with the allocated resources to minimize the system valid latency.Furthermore,considering the differences in the data volume of the tasks,which will induce the waste of the resources for the tasks finished in advance.Thus,the tasks with similar priorities are graded into the same group,and the serial and parallel processing strategies are performed intra-group and inter-group simultaneously.Compared with the other four strategies in four railway monitoring scenarios,the proposed strategies proved latency efficiency to the high-priority tasks,and the system valid latency is reduced synchronously.The performance of the railway environment monitoring system in security and efficiency will be promoted greatly with the proposed scheme and strategies.展开更多
The principle and control for solidification present crucial challenges.Through in situ and real time observation on the solidification of M50 bearing steel,here we discovered that the base of conventional dendritic a...The principle and control for solidification present crucial challenges.Through in situ and real time observation on the solidification of M50 bearing steel,here we discovered that the base of conventional dendritic arms is constituted by a primary semi-solid matrix.Due to the superimposition of temperature fluctuations from the large to the subtle scale,multi-scale dendritic patterns will sequentially emerge and evolve in the primary semi-solid matrix.These findings redefine the essence of multi-scale dendrites as the multi-scale segregation patterns in the primary semi-solid matrix,reconstitute the time and space sequence in the formation of multi-scale dendrites,and reveal the superimposition of temperature fluctuation as the driving principle.These new understandings will fundamentally influence the solidification field.These results also indicate important engineering applications,such as designing multi-scale dendrites,controlling the dendritic segregation and eliminating the detrimental eutectics.展开更多
In this work,the antibacterial activity of cotton containing silver nanocapsules prepared by atmospheric pressure plasma(APP)deposition is investigated.The nanocapsules consist of a shell and a silver nanoparticle(Ag ...In this work,the antibacterial activity of cotton containing silver nanocapsules prepared by atmospheric pressure plasma(APP)deposition is investigated.The nanocapsules consist of a shell and a silver nanoparticle(Ag NP)core,where the core is used to bring antibacterial activity,and the shell is utilized to suppress the potential toxicity of Ag NPs.The surface morphology and the elements of the samples are analyzed by scanning electron microscopy(SEM),energy dispersive x-ray and x-ray photoelectron spectroscopy(XPS).The SEM results show that the skin of the cotton fibers will fall off gradually after APP treatment over 3 min,and the XPS results show that the Ag content will rise to 1.6%after APP deposition for 10 min.Furthermore,the antimicrobial activity tests show that the reduction rates of Escherichia coli and Staphylococcus aureus can achieve 100%when the sample is treated for 10 min,which exhibits excellent antibacterial activity.In addition,the UV absorption properties of the cotton will also be correspondingly improved,which brings a broader application prospect for antibacterial cotton.展开更多
Although some progress in plasma modification of the polytetrafluoroethylene(PTFE) surface has been made recently,its adhesion strength still needs to be further improved.In this work,the surface of a PTFE sample was ...Although some progress in plasma modification of the polytetrafluoroethylene(PTFE) surface has been made recently,its adhesion strength still needs to be further improved.In this work,the surface of a PTFE sample was treated with a two-step in-situ method.Firstly,the PTFE surface was treated with capacitively coupled Ar plasma to improve its mechanical interlocking performance;then,Ar+NH_(3)+CH_(4) plasma was used to deposit an a-CNx:H cross-linking layer on the PTFE surface to improve the molecular bonding ability.After treatment,a high specific surface area of 2.20 and a low F/C ratio of 0.32 were achieved on the PTFE surface.Its surface free energy was increased significantly and its maximum adhesion strength reached77.1 N·10 mm^(-1),which is 56% higher than that of the single-step Ar plasma-treated sample and32% higher than that of the single-step Ar+CH_(4)+NH_(3) plasma-treated sample.展开更多
In our recently published article,“Multi-scale dendritic patterns sequentially superimposed in a primary semi-solid matrix”[Journal of Materials Science&Technology 107(2022)26-33]”,the picture of Fig.9 was misa...In our recently published article,“Multi-scale dendritic patterns sequentially superimposed in a primary semi-solid matrix”[Journal of Materials Science&Technology 107(2022)26-33]”,the picture of Fig.9 was misapplied in Fig.8.It caused the omission of Fig.8 described in the original manuscript.This corrigendum corrects the picture of Fig.8.This corrigendum does not affect the conclusions of that paper.The authors would like to apologize for any inconvenience caused.展开更多
Both the Active Flow Control(AFC)and the variable-camber technology are considered as efficient ways to enhance the aerodynamic performance of an aircraft.The present study investigated the feasibility of the combinat...Both the Active Flow Control(AFC)and the variable-camber technology are considered as efficient ways to enhance the aerodynamic performance of an aircraft.The present study investigated the feasibility of the combination of a Co-Flow Jet(CFJ)airfoil and a parabolic flap,where the Reynolds Average Navier-Stokes(RANS)equations and the Spalart-Allmaras(S-A)turbulence model were exploited for the numerical simulation.Several significant geometric parameters,including the injection slot location,the suction slot location,the injection slot angle,the suction slot angle and the airfoil Suction Surface Translation(SST),were selected to study their effects on the aerodynamics of the proposed configuration.Then,an optimized design was created and compared with the baseline airfoil.The results show that the CFJ airfoil combined with the parabolic flap is more beneficial to the aerodynamic performance enhancement at small angles of attack.It is preferable to locate the injection slot at a 2%chord-wise location and the suction slot at a 75%chord-wise location.Both the decrease of the injection slot angle and the augmentation of the suction slot angle could reduce the drag.Furthermore,the SST of 0.5%chord is selected due to its high gain in the corrected aerodynamic efficiency at small angles of attack.Compared with the baseline,the optimized design could increase the lift coefficient and the corrected lift-to-drag ratio by 32.1%and 93.8%respectively at the angle of attack a=4°.展开更多
In a sample quenched during equiaxed solidification of an Al-5 wt.% Cu alloy, the multi-scales 3-dimensional morphology of equiaxed dendrite was observed. The slim primary stem and secondary branches constitute the fr...In a sample quenched during equiaxed solidification of an Al-5 wt.% Cu alloy, the multi-scales 3-dimensional morphology of equiaxed dendrite was observed. The slim primary stem and secondary branches constitute the frame of dendrite, and rows of dense tertiary branches further divide the 3-dimensional space. In the divided space, the quartic branches grow further. The dendritic branches,which are perpendicular to each other, can change their growth directions and coalesce into a whole. In the tertiary branches and quartic branches, the formation of double branch structures is induced by competitive growth. The branch that wins in the competitive growth will produce a cabbage-like structure by wrapping the failed branches. In addition, the side branch can also wrap the original parent branch to produce cabbage-like structures. Depending on the historical growth direction, the dendritic arms can form vein-like and spicate structures, and the shapes of single dendritic arm may be the cylinder, plate and trapezoid platform. According to the compositions and etching morphology, the single dendritic arm in the final solidification structures should coalesce from a fine porous structure. The porous structures at different length-scales are principally induced by the preferential growth. Based on 3-dimensional morphology of equiaxed dendrite, a new research object for the investigation of microsegregation was suggested.展开更多
Highly efficient and green ammonia production is an important demand for modern agriculture.In this study,a two-step ammonia production method is developed using a gliding arc discharge in combination with Cu/Cu_(2)O ...Highly efficient and green ammonia production is an important demand for modern agriculture.In this study,a two-step ammonia production method is developed using a gliding arc discharge in combination with Cu/Cu_(2)O electrocatalysis.In this method,NO_(x)is provided by the gliding arc discharge and then electrolyzed by Cu/Cu_(2)O after alkaline absorption.The electrical characteristics,the optical characteristics and the NO_(x)production are investigated in discharges at different input voltage and the gas flow.The dependence of ammonia production through Cu/Cu_(2)O electrocatalysis on pH value and reduction potential are determined by colorimetric method.In our study,two discharge modes are observed.At high input voltage and low gas flow,the discharge is operated with a stable plasma channel which is called the steady arc gliding discharge mode(A-G mode).As lowering input voltage and raising gas flow,the plasma channel is destroyed and high frequency breakdown occurs instead,which is known as the breakdown gliding discharge mode(B-G mode).The optimal NO_(x)production of 7.34 mmol h^(-1)is obtained in the transition stage of the two discharge modes.The ammonia yield reaches0.402 mmol h^(-1)cm^(-2)at pH value of 12.7 and reduction potential of-1.0 V versus reversible hydrogen electrode(RHE).展开更多
Solidification is an important branch of material science.By model calculation and in-situ observation in this work,distinct from traditional solidification of continuous solid growth,the evolution of discrete so-lidi...Solidification is an important branch of material science.By model calculation and in-situ observation in this work,distinct from traditional solidification of continuous solid growth,the evolution of discrete so-lidification was investigated,and a new principle for discrete solidification is established based on segre-gation evolution in a semi-solid matrix.The solidification evolution of Al-2 wt.%Cu alloy was investigated by model calculation under different initial undercooling and cooling rates,under superimposed multi-scale temperature fluctuations,and under variable temperature fluctuations.The initiation and propa-gation of segregation fluctuations in semi-solid matrix were verified within a traditional dendritic arm.The alternate solid elements evolved from semi-solid matrix act as periodic dams inhibiting serious seg-regation.Based on the new solidification principle,a multi-scale dendritic pattern was reproduced in a two-dimensional calculation.The new solidification principle reveals the essence of multi-scale mi-crostructures as multi-scale segregation patterns and highlights the feasibility of controlling multi-scale microstructures and segregations.展开更多
Osteosarcoma is the most common malignant bone tumor and is frequently diagnosed in juvenile.Cellular senescence is a fundamental hallmark of osteosarcoma and plays a vital role in the initiation and progression of ag...Osteosarcoma is the most common malignant bone tumor and is frequently diagnosed in juvenile.Cellular senescence is a fundamental hallmark of osteosarcoma and plays a vital role in the initiation and progression of aging and tumorigenesis.Long non-coding RNAs(lncRNAs)are implicated in tumorigenesis.In this study,six cellular senescence-related lncRNAs with independent prognostic significance in juvenile osteosarcoma patients were identified through univariate Cox regression analysis,least absolute shrinkage and selection operator(LASSO)regression analysis,and multivariate Cox regression analysis.Prognostic significance was further confirmed by Kaplan-Meier(KM)survival curves,co-expression interaction networks,and sankey diagrams.A prognostic model of cellular senescence-related genes in juvenile osteosarcoma patients was then constructed using multivariate Cox regression analysis based on these six genes.High-and low-risk groups were identified according to the median risk score calculated by the prognostic model.The favorable prognostic significance of this model was demonstrated through survival curves,receiver operating characteristic(ROC)curves,distribution scatter plots and lncRNA expression heatmaps.Furthermore,cellular senescence-related lncRNAs were validated by enrichment analysis,immunological correlation analysis,m^(6)A correlation analysis,and drug sensitivity correlation analysis.These findings are important for improving the prognosis of juvenile osteosarcoma patients and understanding the mechanisms underlying cellular senescence in juvenile osteosarcoma development.展开更多
With the rapid growth of urbanization and the increasing demand for transportation, urban traffic congestion has become a hindrance to individuals’ travel experience. Urban intersections are one of the primary source...With the rapid growth of urbanization and the increasing demand for transportation, urban traffic congestion has become a hindrance to individuals’ travel experience. Urban intersections are one of the primary sources of traffic congestion, and these bottlenecks have a negative impact not only on traffic efficacy but also on the surrounding road traffic in the region. To alleviate urban traffic congestion, cyber-physical systems have been widely implemented in the transportation industry, allowing for the perception, analysis, calculation, and dispatching of urban traffic flow, as well as making urban transportation safe, efficient, and quick. As the system scale and functions increase, system design has become increasingly complex, necessitating a deeper comprehension of the system’s structure and interaction relationships to construct a stable and reliable system. Therefore, this study proposes a method for designing cyber-physical systems for urban traffic intersections based on Model-Based Systems Engineering (MBSE). This method models and analyses exhaustively the system’s requirements, functions, and logical architecture using System Modeling Language (SysML). After the architecture design has been completed, an architecture verification and optimization method based on Failure Mode and Effect Analysis (FMEA) for urban road intersection cyber-physical systems is utilized to analyze the architecture’s reliability by analyzing the failure modes of activities and to optimize the system architecture to improve the design’s efficiency and reliability.展开更多
基金granted by the Xinjiang Geological Exploration Fund。
文摘The northwestern margin of Junggar Basin is the region with the richest oil sand resources in China.For better understanding the enrichment rules and deployment of exploration and development of regional oil sand,it is of great scientific significance to study the accumulation conditions of oil sand in different strata and mining areas of the Junggar Basin.Through a large number of field investigations,drilling verification and sampling tests,it is found that the oil sand in the region covers an area of 2000 km^(2),with shallow and thick reservoir,and predicted resource of 180 million tons.The oil sand resources are mainly distributed in four geological strata,namely the Middle Triassic Karamay Formation,Early Jurassic Badaowan Formation,Late Jurassic Qigu Formation,and Early Cretaceous Qingshuihe Formation.The reservoir is mainly composed of sandstone with high porosity and permeability,and the reservoir space is mainly intergranular pores with a medium average oil content.The oil sand deposit in the region is a typical destructive oil reservoir.The crude oil in the oil sand layer is degraded and thickened from the deep to the shallow,the content of saturated hydrocarbon decreased,and the content of aromatic hydrocarbon,non-hydrocarbon and asphaltene increased.The oil source comes from the deep Permian hydrocarbon-generating depression.Unconformities,faults and marginal fan delta-braided river depositional systems constitute effective migration and storage systems.Caprocks of the Upper Triassic Baijiantan Formation,Lower Jurassic Sangonghe Formation and Lower Cretaceous Hutubihe Formation were formed by three large scale lake transgressions.The Indosinian,Yanshan and Late Yanshan movements are the main driving forces for the migration of deep oil and gas to the shallow edge to form oil sand deposits.It is considered that the oil sand in the northwestern margin of Junggar Basin is of a slope complex migration type.
基金Foundation of the Special Research Assistant of Chinese Academy of Sciences(No.E0290A0301)。
文摘High-Altitude Long-Endurance(HALE)solar-powered Unmanned Aircraft Vehicles(UAVs)can utilize solar energy as power source and maintain extremely long cruise endurance,which has attracted extensive attentions from researchers.Trajectory optimization is a promising way to achieve superior flight time because of the finite solar energy absorbed in a day.In this work,a method of trajectory optimization and guidance for HALE solar-powered aircraft based on a Reinforcement Learning(RL)framework is introduced.According to flight and environment information,a neural network controller outputs commands of thrust,attack angle,and bank angle to realize an autonomous flight based on energy maximization.The validity of the proposed method was evaluated in a 5-km radius area in simulation,and results have shown that after one day-night cycle,the battery energy of the RL-controller was improved by 31%and 17%compared with those of a Steady-State(SS)strategy with a constant speed and a constant altitude and a kind of statemachine strategy,respectively.In addition,results of an uninterrupted flight test have shown that the endurance of the RL controller was longer than those of the control cases.
基金Supported by the National Natural Science Foundation of China(61503384,61603393)Natural Science Foundation of Jiangsu(BK20150199,BK20160275)+1 种基金the Foundation Research Funds for the Central Universities(2015QNA65)the Postdoctoral Foundation of Jiangsu Province(1501081B)
文摘Although industrial processes often perform perfectly under design conditions, they may deviate from the optimal operating point owing to parameters drift, environmental disturbances, etc. Thus, it is necessary to develop efficacious strategies or procedure to assess the process performance online. In this paper, we explore the issue of operating optimality assessment for complex industrial processes based on performance-similarity considering nonlinearities and outliers simultaneously, and a general enforced online performance assessment framework is proposed. In the offline part, a new and modified total robust kernel projection to latent structures algorithm,T-KPRM, is proposed and used to evaluate the complex nonlinear industrial process, which can effectively extract the optimal-index-related process variation information from process data and establish assessment models for each performance grades overcoming the effects of outlier. In the online part, the online assessment results can be obtained by calculating the similarity between the online data from a sliding window and each of the performance grades. Furthermore, in order to improve the accuracy of online assessment, we propose an online assessment strategy taking account of the effects of noise and process uncertainties. The Euclidean distance between the sliding data window and the optimal evaluation level is employed to measure the contribution rates of variables, which indicate the possible reason for the non-optimal operating performance. The proposed framework is tested on a real industrial case: dense medium coal preparation process, and the results shows the efficiency of the proposed method comparing to the existing method.
基金supported by the National Natural Science Foundation of China(No.61903023)the Natural Science Foundation of Bejing Municipality(No.4204110)+1 种基金State Key Laboratory of Rail Traffic Control and Safety(No.RCS2020ZT006,RCS2021ZT006)the Fundamental Research Funds for the Central Universities(No.2020JBM087).
文摘Response speed is vital for the railway environment monitoring system,especially for the sudden-onset disasters.The edge-cloud collaboration scheme is proved efficient to reduce the latency.However,the data characteristics and communication demand of the tasks in the railway environment monitoring system are all different and changeable,and the latency contribution of each task to the system is discrepant.Hence,two valid latency minimization strategies based on the edge-cloud collaboration scheme is developed in this paper.First,the processing resources are allocated to the tasks based on the priorities,and the tasks are processed parallly with the allocated resources to minimize the system valid latency.Furthermore,considering the differences in the data volume of the tasks,which will induce the waste of the resources for the tasks finished in advance.Thus,the tasks with similar priorities are graded into the same group,and the serial and parallel processing strategies are performed intra-group and inter-group simultaneously.Compared with the other four strategies in four railway monitoring scenarios,the proposed strategies proved latency efficiency to the high-priority tasks,and the system valid latency is reduced synchronously.The performance of the railway environment monitoring system in security and efficiency will be promoted greatly with the proposed scheme and strategies.
基金supported by the Youth Talent Project of Shenyang National Laboratory for Materials Science(Grant No.L2019F46)the Project to Strengthen Industrial Development at the Grass-roots Level(Grant No.TC190A4DA/35)。
文摘The principle and control for solidification present crucial challenges.Through in situ and real time observation on the solidification of M50 bearing steel,here we discovered that the base of conventional dendritic arms is constituted by a primary semi-solid matrix.Due to the superimposition of temperature fluctuations from the large to the subtle scale,multi-scale dendritic patterns will sequentially emerge and evolve in the primary semi-solid matrix.These findings redefine the essence of multi-scale dendrites as the multi-scale segregation patterns in the primary semi-solid matrix,reconstitute the time and space sequence in the formation of multi-scale dendrites,and reveal the superimposition of temperature fluctuation as the driving principle.These new understandings will fundamentally influence the solidification field.These results also indicate important engineering applications,such as designing multi-scale dendrites,controlling the dendritic segregation and eliminating the detrimental eutectics.
基金supported by National Natural Science Foundation of China(Nos.11975163 and 12175160)together with a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘In this work,the antibacterial activity of cotton containing silver nanocapsules prepared by atmospheric pressure plasma(APP)deposition is investigated.The nanocapsules consist of a shell and a silver nanoparticle(Ag NP)core,where the core is used to bring antibacterial activity,and the shell is utilized to suppress the potential toxicity of Ag NPs.The surface morphology and the elements of the samples are analyzed by scanning electron microscopy(SEM),energy dispersive x-ray and x-ray photoelectron spectroscopy(XPS).The SEM results show that the skin of the cotton fibers will fall off gradually after APP treatment over 3 min,and the XPS results show that the Ag content will rise to 1.6%after APP deposition for 10 min.Furthermore,the antimicrobial activity tests show that the reduction rates of Escherichia coli and Staphylococcus aureus can achieve 100%when the sample is treated for 10 min,which exhibits excellent antibacterial activity.In addition,the UV absorption properties of the cotton will also be correspondingly improved,which brings a broader application prospect for antibacterial cotton.
文摘Although some progress in plasma modification of the polytetrafluoroethylene(PTFE) surface has been made recently,its adhesion strength still needs to be further improved.In this work,the surface of a PTFE sample was treated with a two-step in-situ method.Firstly,the PTFE surface was treated with capacitively coupled Ar plasma to improve its mechanical interlocking performance;then,Ar+NH_(3)+CH_(4) plasma was used to deposit an a-CNx:H cross-linking layer on the PTFE surface to improve the molecular bonding ability.After treatment,a high specific surface area of 2.20 and a low F/C ratio of 0.32 were achieved on the PTFE surface.Its surface free energy was increased significantly and its maximum adhesion strength reached77.1 N·10 mm^(-1),which is 56% higher than that of the single-step Ar plasma-treated sample and32% higher than that of the single-step Ar+CH_(4)+NH_(3) plasma-treated sample.
文摘In our recently published article,“Multi-scale dendritic patterns sequentially superimposed in a primary semi-solid matrix”[Journal of Materials Science&Technology 107(2022)26-33]”,the picture of Fig.9 was misapplied in Fig.8.It caused the omission of Fig.8 described in the original manuscript.This corrigendum corrects the picture of Fig.8.This corrigendum does not affect the conclusions of that paper.The authors would like to apologize for any inconvenience caused.
基金supported by the National Natural Science Foundation of China(Nos.12102431,12002340,and 11902320).
文摘Both the Active Flow Control(AFC)and the variable-camber technology are considered as efficient ways to enhance the aerodynamic performance of an aircraft.The present study investigated the feasibility of the combination of a Co-Flow Jet(CFJ)airfoil and a parabolic flap,where the Reynolds Average Navier-Stokes(RANS)equations and the Spalart-Allmaras(S-A)turbulence model were exploited for the numerical simulation.Several significant geometric parameters,including the injection slot location,the suction slot location,the injection slot angle,the suction slot angle and the airfoil Suction Surface Translation(SST),were selected to study their effects on the aerodynamics of the proposed configuration.Then,an optimized design was created and compared with the baseline airfoil.The results show that the CFJ airfoil combined with the parabolic flap is more beneficial to the aerodynamic performance enhancement at small angles of attack.It is preferable to locate the injection slot at a 2%chord-wise location and the suction slot at a 75%chord-wise location.Both the decrease of the injection slot angle and the augmentation of the suction slot angle could reduce the drag.Furthermore,the SST of 0.5%chord is selected due to its high gain in the corrected aerodynamic efficiency at small angles of attack.Compared with the baseline,the optimized design could increase the lift coefficient and the corrected lift-to-drag ratio by 32.1%and 93.8%respectively at the angle of attack a=4°.
文摘In a sample quenched during equiaxed solidification of an Al-5 wt.% Cu alloy, the multi-scales 3-dimensional morphology of equiaxed dendrite was observed. The slim primary stem and secondary branches constitute the frame of dendrite, and rows of dense tertiary branches further divide the 3-dimensional space. In the divided space, the quartic branches grow further. The dendritic branches,which are perpendicular to each other, can change their growth directions and coalesce into a whole. In the tertiary branches and quartic branches, the formation of double branch structures is induced by competitive growth. The branch that wins in the competitive growth will produce a cabbage-like structure by wrapping the failed branches. In addition, the side branch can also wrap the original parent branch to produce cabbage-like structures. Depending on the historical growth direction, the dendritic arms can form vein-like and spicate structures, and the shapes of single dendritic arm may be the cylinder, plate and trapezoid platform. According to the compositions and etching morphology, the single dendritic arm in the final solidification structures should coalesce from a fine porous structure. The porous structures at different length-scales are principally induced by the preferential growth. Based on 3-dimensional morphology of equiaxed dendrite, a new research object for the investigation of microsegregation was suggested.
文摘Highly efficient and green ammonia production is an important demand for modern agriculture.In this study,a two-step ammonia production method is developed using a gliding arc discharge in combination with Cu/Cu_(2)O electrocatalysis.In this method,NO_(x)is provided by the gliding arc discharge and then electrolyzed by Cu/Cu_(2)O after alkaline absorption.The electrical characteristics,the optical characteristics and the NO_(x)production are investigated in discharges at different input voltage and the gas flow.The dependence of ammonia production through Cu/Cu_(2)O electrocatalysis on pH value and reduction potential are determined by colorimetric method.In our study,two discharge modes are observed.At high input voltage and low gas flow,the discharge is operated with a stable plasma channel which is called the steady arc gliding discharge mode(A-G mode).As lowering input voltage and raising gas flow,the plasma channel is destroyed and high frequency breakdown occurs instead,which is known as the breakdown gliding discharge mode(B-G mode).The optimal NO_(x)production of 7.34 mmol h^(-1)is obtained in the transition stage of the two discharge modes.The ammonia yield reaches0.402 mmol h^(-1)cm^(-2)at pH value of 12.7 and reduction potential of-1.0 V versus reversible hydrogen electrode(RHE).
基金supported by the General Program of the National Natural Science Foundation of China(Grant No.52271041)the Key Program of the National Natural Science Foundation of China(Grant No.52031013).
文摘Solidification is an important branch of material science.By model calculation and in-situ observation in this work,distinct from traditional solidification of continuous solid growth,the evolution of discrete so-lidification was investigated,and a new principle for discrete solidification is established based on segre-gation evolution in a semi-solid matrix.The solidification evolution of Al-2 wt.%Cu alloy was investigated by model calculation under different initial undercooling and cooling rates,under superimposed multi-scale temperature fluctuations,and under variable temperature fluctuations.The initiation and propa-gation of segregation fluctuations in semi-solid matrix were verified within a traditional dendritic arm.The alternate solid elements evolved from semi-solid matrix act as periodic dams inhibiting serious seg-regation.Based on the new solidification principle,a multi-scale dendritic pattern was reproduced in a two-dimensional calculation.The new solidification principle reveals the essence of multi-scale mi-crostructures as multi-scale segregation patterns and highlights the feasibility of controlling multi-scale microstructures and segregations.
基金supported by National Key Research and Development Program of China(2020YFE0201600)National Nature Science Foundation(81973877,82174408)+1 种基金Shanghai Collaborative Innovation Center of Industrial Transformation of Hospital TCM PreparationShanghai Top Priority Research Center construction project(2022ZZ01009).
文摘Osteosarcoma is the most common malignant bone tumor and is frequently diagnosed in juvenile.Cellular senescence is a fundamental hallmark of osteosarcoma and plays a vital role in the initiation and progression of aging and tumorigenesis.Long non-coding RNAs(lncRNAs)are implicated in tumorigenesis.In this study,six cellular senescence-related lncRNAs with independent prognostic significance in juvenile osteosarcoma patients were identified through univariate Cox regression analysis,least absolute shrinkage and selection operator(LASSO)regression analysis,and multivariate Cox regression analysis.Prognostic significance was further confirmed by Kaplan-Meier(KM)survival curves,co-expression interaction networks,and sankey diagrams.A prognostic model of cellular senescence-related genes in juvenile osteosarcoma patients was then constructed using multivariate Cox regression analysis based on these six genes.High-and low-risk groups were identified according to the median risk score calculated by the prognostic model.The favorable prognostic significance of this model was demonstrated through survival curves,receiver operating characteristic(ROC)curves,distribution scatter plots and lncRNA expression heatmaps.Furthermore,cellular senescence-related lncRNAs were validated by enrichment analysis,immunological correlation analysis,m^(6)A correlation analysis,and drug sensitivity correlation analysis.These findings are important for improving the prognosis of juvenile osteosarcoma patients and understanding the mechanisms underlying cellular senescence in juvenile osteosarcoma development.
基金supported by the National Key R&D Program of China(2021YFB2501000).
文摘With the rapid growth of urbanization and the increasing demand for transportation, urban traffic congestion has become a hindrance to individuals’ travel experience. Urban intersections are one of the primary sources of traffic congestion, and these bottlenecks have a negative impact not only on traffic efficacy but also on the surrounding road traffic in the region. To alleviate urban traffic congestion, cyber-physical systems have been widely implemented in the transportation industry, allowing for the perception, analysis, calculation, and dispatching of urban traffic flow, as well as making urban transportation safe, efficient, and quick. As the system scale and functions increase, system design has become increasingly complex, necessitating a deeper comprehension of the system’s structure and interaction relationships to construct a stable and reliable system. Therefore, this study proposes a method for designing cyber-physical systems for urban traffic intersections based on Model-Based Systems Engineering (MBSE). This method models and analyses exhaustively the system’s requirements, functions, and logical architecture using System Modeling Language (SysML). After the architecture design has been completed, an architecture verification and optimization method based on Failure Mode and Effect Analysis (FMEA) for urban road intersection cyber-physical systems is utilized to analyze the architecture’s reliability by analyzing the failure modes of activities and to optimize the system architecture to improve the design’s efficiency and reliability.
