针对炮钢材料25Cr3Mo3NiNbZr钢,结合可控离子渗入(Programable ion permeation,PIP)与激光淬火(Laser quenching,LQ)两种工艺优势进行复合处理以提升其表面性能。试验材料经调质预处理后,先进行PIP处理,再以不同扫描速度进行激光淬火。...针对炮钢材料25Cr3Mo3NiNbZr钢,结合可控离子渗入(Programable ion permeation,PIP)与激光淬火(Laser quenching,LQ)两种工艺优势进行复合处理以提升其表面性能。试验材料经调质预处理后,先进行PIP处理,再以不同扫描速度进行激光淬火。通过金相观察、XRD分析、显微硬度测试、电化学腐蚀以及中性盐雾试验等方法表征试样性能。结果表明,在2.31~3.00 J/mm^(2)的激光能量密度扫描下,部分化合物层发生了分解,降低了表面硬度;扩散层生成含氮马氏体,次表层硬度峰值得到提高。激光扫描速度为39 mm/s(激光能量密度为2.31 J/mm^(2))时工艺最佳,此时组织细化,含氮马氏体转变较多,表层氮化物损失较少,有效缓解“蛋壳效应”。PIP/LQ复合工艺处理试样的耐腐蚀性能虽低于PIP处理试样,但仍高于未处理试样,因此,PIP/LQ复合工艺在提高炮钢材料表面性能方面具有可行性。展开更多
针对传统α能谱测量系统存在的本底噪声高、能量分辨率受限等问题,研制了基于FPGA技术的数字多道分析模块与PIPS半导体探测器相结合的新一代α能谱测量系统。该系统设计基于FPGA的多参数数字多道处理架构,利用硬件描述语言实现高速脉冲...针对传统α能谱测量系统存在的本底噪声高、能量分辨率受限等问题,研制了基于FPGA技术的数字多道分析模块与PIPS半导体探测器相结合的新一代α能谱测量系统。该系统设计基于FPGA的多参数数字多道处理架构,利用硬件描述语言实现高速脉冲幅度提取算法,开发了自适应基线恢复技术和波形动态甄别机制。实验数据表明,该系统能量分辨率最低可达到16.293 ke V@5.486 MeV(FWHM),支持8192道能谱分析,具备多探测器同步采集能力,为环境放射性监测、核安全保障、食品安全等领域的超低水平α核素分析提供了可靠的技术手段。展开更多
Graphene,owing to its exceptional electronic,optical,thermal,and mechanical properties,has emerged as a highly promising material.Currently,the synthesis of large-area graphene films on metal substrates via chemical v...Graphene,owing to its exceptional electronic,optical,thermal,and mechanical properties,has emerged as a highly promising material.Currently,the synthesis of large-area graphene films on metal substrates via chemical vapor deposition remains the predominant approach for producing high-quality graphene.To realize the potential applications of graphene,it is essential to transfer graphene films to target substrates in a manner that is non-destructive,clean,and efficient,as this significantly affects the performance of graphene devices.This review examines the current methods for graphene transfer from three perspectives:non-destructive transfer,clean transfer,and high-efficiency transfer.It analyzes and compares the advancements and limitations of various transfer techniques.Finally,the review identifies the key challenges faced by current graphene transfer methods and anticipates future developmental prospects.展开更多
Through literature analysis and case study, the introduction history, variety selection (high bush, half high bush, low bush) and regional cultivation techniques of blueberry in China were summarized, and the practica...Through literature analysis and case study, the introduction history, variety selection (high bush, half high bush, low bush) and regional cultivation techniques of blueberry in China were summarized, and the practical effects of precision cultivation (water and fertilizer integration, wild planting) and under-forest economic model (forest-blueberry-fungus system, ecological tourism) were evaluated. It provided a technical reference for expanding the planting scale of blueberry and improving the fruit quality.展开更多
The addition of cold flow improvers(CFIs)is considered as the optimum strategy to improve the cold flow properties(CFPs)of diesel fuels,but this strategy is always limited by the required large dosage.To obtain low-do...The addition of cold flow improvers(CFIs)is considered as the optimum strategy to improve the cold flow properties(CFPs)of diesel fuels,but this strategy is always limited by the required large dosage.To obtain low-dosage and high-efficiency CFIs for diesel,1,2,3,6-tetrahydrophthalic anhydride(THPA)was introduced as a third and polar monomer to enhance the depressive effects of alkyl methacrylatetrans anethole copolymers(C_(14)MC-TA).The terpolymers of alkyl methacrylate-trans anethole-1,2,3,6-tetrahydrophthalic anhydride(C_(14)MC-TA-THPA)were synthesized and compared with the binary copolymers of C_(14)MC-TA and alkyl methacrylate-1,2,3,6-tetrahydrophthalic anhydride(C_(14)MC-THPA).Results showed that C_(14)MC-THPA achieved the best depressive effects on the cold filter plugging point(CFPP)and solid point(SP)by 11℃and 16℃at a dosage of 1250 mg/L and monomer ratio of 6:1,while 1500mg/L C_(14)MC-TA(1:1)reached the optimal depressive effects on the CFPP and SP by 12℃and 18℃.THPA introduction significantly improved the depressive effects of C_(14)MC-TA.Lower dosages of C_(14)MCTA-THPA in diesel exerted better improvement effects on the CFPP and SP than that of C_(14)MC-TA and C_(14)MC-THPA.When the monomer ratio and dosage were 6:0.6:0.4 and 1000 mg/L,the improvement effect of C_(14)MC-TA-THPA on diesel reached the optimum level,and the CFPP and SP were reduced by 13℃and 19℃,respectively.A 3D nonlinear surface diagram fitted by a mathematical model was also used for the first time to better understand the relationships of monomer ratios,dosages,and depressive effects of CFIs in diesel.Surface analysis results showed that C_(14)MC-TA-THPA achieved the optimum depressive effects at a monomer ratio of 6:0.66:0.34 and dosage of 1000 mg/L,and the CFPP and SP decreased by 14℃ and 19℃,respectively.The predicted results were consistent with the actual ones.Additionally,the improvement mechanism of these copolymers in diesel was also explored.展开更多
The double-beam system is a crucial foundational structure in industry,with extensive application contexts and significant research value.The double-beam system with damping and gyroscopic effects is termed as the dam...The double-beam system is a crucial foundational structure in industry,with extensive application contexts and significant research value.The double-beam system with damping and gyroscopic effects is termed as the damped gyroscopic double-beam system.In such systems,the orthogonality conditions of the undamped double-beam system are no longer applicable,rendering it impossible to decouple them in modal space using the modal superposition method(MSM) to obtain analytical solutions.Based on the complex modal method and state space method,this paper takes the damped pipe-in-pipe(PIP) system as an example to solve this problem.The concepts of the original system and adjoint system are introduced,and the orthogonality conditions of the damped PIP system are given in the state-space.Based on the derived orthogonality conditions,the transient and steady-state response solutions are obtained.In the numerical discussion section,the convergence and accuracy of the solutions are verified.In addition,the dynamic responses of the system under different excitations and initial conditions are studied,and the forward and reverse synchronous vibrations in the PIP system are discussed.Overall,the method presented in this paper provides a convenient way to analyze the dynamics of the damped gyroscopic double-beam system.展开更多
Gamma titanium-aluminum intermetallic compounds(γ-TiAl)have gained considerable attentions in the aerospace industry due to their exceptional thermal resilience and comprehensive attributes,making them a prime exampl...Gamma titanium-aluminum intermetallic compounds(γ-TiAl)have gained considerable attentions in the aerospace industry due to their exceptional thermal resilience and comprehensive attributes,making them a prime example of lightweight and advanced materials.To address the frequent occurrence of burns and severe tool deterioration during the process of high-efficiency deep grinding(HEDG)onγ-TiAl alloys,ultrasonic vibration-assisted high-efficiency deep grinding(UVHEDG)has been emerged.Results indicate that in UVHEDG,the grinding temperature is on average 15.4%lower than HEDG due to the employment of ultrasonic vibrations,enhancing coolant penetration into the grinding area and thus reducing heat generation.Besides,UVHEDG possesses superior performance in terms of grinding forces compared to HEDG.As the material removal volume(MRV)increases,the tangential grinding force(F_(t))and normal grinding force(F_(n))of UVHEDG increase but to a lesser extent than in HEDG,with an average reduction of16.25%and 14.7%,respectively.UVHEDG primarily experiences microfracture of grains,whereas HEDG undergoes large-scale wear later in the process due to increased grinding forces.The surface roughness(R_(a))characteristics of UVHEDG are superior,with the average value of R_(a)decreasing by 46.5%compared to HEDG as MRV increases.The surface morphology in UVHEDG exhibits enhanced smoothness and a shallower layer of plastic deformation.Grinding chips generated by UVHEDG show a more shear-like shape,with the applied influence of ultrasonic vibration on chip morphology,thereby impacting material removal behaviors.These aforementioned findings contribute to enhanced machining efficiency and product quality ofγ-TiAl alloys after employing ultrasonic vibrations into HEDG.展开更多
To solve the problem of only surface carbonation and realize high-efficiency carbonation of recycled coarse aggregate,the method of carbonated recycled coarse aggregate with nano materials pre-soaking was first put fo...To solve the problem of only surface carbonation and realize high-efficiency carbonation of recycled coarse aggregate,the method of carbonated recycled coarse aggregate with nano materials pre-soaking was first put forward.The carbonation effect of modified recycled coarse aggregate with three different carbonation methods was evaluated,and water absorption,apparent density and crush index of modified recycled coarse aggregate were measured.Combined with XRD,SEM,and MIP microscopic analysis,the high-efficiency carbonation strengthening mechanism of modified recycled coarse aggregate was revealed.The experimental results show that,compared with the non-carbonated recycled coarse aggregate,the physical and microscopic properties of carbonated recycled coarse aggregate are improved.The method of carbonation with nano-SiO_(2) pre-soaking can realize the high-efficiency carbonation of recycled coarse aggregate,for modified recycled coarse aggregate with the method,water absorption is reduced by 23.03%,porosity is reduced by 44.06%,and the average pore diameter is 21.82 nm.The high-efficiency carbonation strengthening mechanism show that the pre-socked nano-SiO_(2) is bound to the hydration product Ca(OH)_(2) of the old mortar with nano-scale C-S-H,which can improve the CO_(2) absorption rate,accelerate the carbonation reaction,generate more stable CaCO_(3) and nano-scale silica gel,and bond to the dense three-dimensional network structure to realize the bidirectional enhancement of nano-materials and pressurized carbonation.It is concluded that the method of carbonation with nano-SiO_(2) pre-soaking is a novel high-efficiency carbonation modification of recycled coarse aggregate.展开更多
Metal halide perovskite solar cells(PSCs)are one of the most promising photovoltaic devices.Over time,many strategies have been adopted to improve PSC efficiency,and the certified efficiency has reached 26.1%.However,...Metal halide perovskite solar cells(PSCs)are one of the most promising photovoltaic devices.Over time,many strategies have been adopted to improve PSC efficiency,and the certified efficiency has reached 26.1%.However,only a few research groups have fabricated PSCs with an efficiency of>25%,indicating that achieving this efficiency remains uncommon.To develop the PSC industry,outstanding talent must be reserved with the latest technologies.Herein,we summarize the recent developments in high-efficiency PSCs(>25%)and highlight their effective strategies in crystal regulation,interface passivation,and component layer structural design.Finally,we propose perspectives based on current research to further enhance the efficiency and promote the commercialization process of PSCs.展开更多
文摘针对传统α能谱测量系统存在的本底噪声高、能量分辨率受限等问题,研制了基于FPGA技术的数字多道分析模块与PIPS半导体探测器相结合的新一代α能谱测量系统。该系统设计基于FPGA的多参数数字多道处理架构,利用硬件描述语言实现高速脉冲幅度提取算法,开发了自适应基线恢复技术和波形动态甄别机制。实验数据表明,该系统能量分辨率最低可达到16.293 ke V@5.486 MeV(FWHM),支持8192道能谱分析,具备多探测器同步采集能力,为环境放射性监测、核安全保障、食品安全等领域的超低水平α核素分析提供了可靠的技术手段。
基金supported by the National Key R&D Program of China(2020YFB2009002).
文摘Graphene,owing to its exceptional electronic,optical,thermal,and mechanical properties,has emerged as a highly promising material.Currently,the synthesis of large-area graphene films on metal substrates via chemical vapor deposition remains the predominant approach for producing high-quality graphene.To realize the potential applications of graphene,it is essential to transfer graphene films to target substrates in a manner that is non-destructive,clean,and efficient,as this significantly affects the performance of graphene devices.This review examines the current methods for graphene transfer from three perspectives:non-destructive transfer,clean transfer,and high-efficiency transfer.It analyzes and compares the advancements and limitations of various transfer techniques.Finally,the review identifies the key challenges faced by current graphene transfer methods and anticipates future developmental prospects.
文摘Through literature analysis and case study, the introduction history, variety selection (high bush, half high bush, low bush) and regional cultivation techniques of blueberry in China were summarized, and the practical effects of precision cultivation (water and fertilizer integration, wild planting) and under-forest economic model (forest-blueberry-fungus system, ecological tourism) were evaluated. It provided a technical reference for expanding the planting scale of blueberry and improving the fruit quality.
基金supported from the Natural Science Foundation Project of Shanghai(Nos.23ZR1425300 and 22ZR1426100)Experimental Technical Team Construction Project of Shanghai Education Commission(No.10110N230080)+1 种基金National Natural Science Foundation of China(No.22075183)Research and Innovation Project of Shanghai Municipal Education Commission(No.2023ZKZD54).
文摘The addition of cold flow improvers(CFIs)is considered as the optimum strategy to improve the cold flow properties(CFPs)of diesel fuels,but this strategy is always limited by the required large dosage.To obtain low-dosage and high-efficiency CFIs for diesel,1,2,3,6-tetrahydrophthalic anhydride(THPA)was introduced as a third and polar monomer to enhance the depressive effects of alkyl methacrylatetrans anethole copolymers(C_(14)MC-TA).The terpolymers of alkyl methacrylate-trans anethole-1,2,3,6-tetrahydrophthalic anhydride(C_(14)MC-TA-THPA)were synthesized and compared with the binary copolymers of C_(14)MC-TA and alkyl methacrylate-1,2,3,6-tetrahydrophthalic anhydride(C_(14)MC-THPA).Results showed that C_(14)MC-THPA achieved the best depressive effects on the cold filter plugging point(CFPP)and solid point(SP)by 11℃and 16℃at a dosage of 1250 mg/L and monomer ratio of 6:1,while 1500mg/L C_(14)MC-TA(1:1)reached the optimal depressive effects on the CFPP and SP by 12℃and 18℃.THPA introduction significantly improved the depressive effects of C_(14)MC-TA.Lower dosages of C_(14)MCTA-THPA in diesel exerted better improvement effects on the CFPP and SP than that of C_(14)MC-TA and C_(14)MC-THPA.When the monomer ratio and dosage were 6:0.6:0.4 and 1000 mg/L,the improvement effect of C_(14)MC-TA-THPA on diesel reached the optimum level,and the CFPP and SP were reduced by 13℃and 19℃,respectively.A 3D nonlinear surface diagram fitted by a mathematical model was also used for the first time to better understand the relationships of monomer ratios,dosages,and depressive effects of CFIs in diesel.Surface analysis results showed that C_(14)MC-TA-THPA achieved the optimum depressive effects at a monomer ratio of 6:0.66:0.34 and dosage of 1000 mg/L,and the CFPP and SP decreased by 14℃ and 19℃,respectively.The predicted results were consistent with the actual ones.Additionally,the improvement mechanism of these copolymers in diesel was also explored.
基金Project supported by the National Natural Science Foundation of China (No. 12272323)。
文摘The double-beam system is a crucial foundational structure in industry,with extensive application contexts and significant research value.The double-beam system with damping and gyroscopic effects is termed as the damped gyroscopic double-beam system.In such systems,the orthogonality conditions of the undamped double-beam system are no longer applicable,rendering it impossible to decouple them in modal space using the modal superposition method(MSM) to obtain analytical solutions.Based on the complex modal method and state space method,this paper takes the damped pipe-in-pipe(PIP) system as an example to solve this problem.The concepts of the original system and adjoint system are introduced,and the orthogonality conditions of the damped PIP system are given in the state-space.Based on the derived orthogonality conditions,the transient and steady-state response solutions are obtained.In the numerical discussion section,the convergence and accuracy of the solutions are verified.In addition,the dynamic responses of the system under different excitations and initial conditions are studied,and the forward and reverse synchronous vibrations in the PIP system are discussed.Overall,the method presented in this paper provides a convenient way to analyze the dynamics of the damped gyroscopic double-beam system.
基金financially supported by the National Natural Science Foundation of China(Nos.92160301,92060203,52175415 and 52205475)the Science Center for Gas Turbine Project(Nos.P2022-AB-Ⅳ-002-001 and P2023-B-Ⅳ-003-001)+4 种基金the Natural Science Foundation of Jiangsu Province(No.BK20210295)the Superior Postdoctoral Project of Jiangsu Province(No.2022ZB215)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX23_0355)the Interdisciplinary Innovation Fund for Doctoral Students of Nanjing University of Aeronautics and Astronautics(KXKCXJJ202305)the Fundamental Research Funds for the Central Universities(Nos.NS2023028 and NG2024015)。
文摘Gamma titanium-aluminum intermetallic compounds(γ-TiAl)have gained considerable attentions in the aerospace industry due to their exceptional thermal resilience and comprehensive attributes,making them a prime example of lightweight and advanced materials.To address the frequent occurrence of burns and severe tool deterioration during the process of high-efficiency deep grinding(HEDG)onγ-TiAl alloys,ultrasonic vibration-assisted high-efficiency deep grinding(UVHEDG)has been emerged.Results indicate that in UVHEDG,the grinding temperature is on average 15.4%lower than HEDG due to the employment of ultrasonic vibrations,enhancing coolant penetration into the grinding area and thus reducing heat generation.Besides,UVHEDG possesses superior performance in terms of grinding forces compared to HEDG.As the material removal volume(MRV)increases,the tangential grinding force(F_(t))and normal grinding force(F_(n))of UVHEDG increase but to a lesser extent than in HEDG,with an average reduction of16.25%and 14.7%,respectively.UVHEDG primarily experiences microfracture of grains,whereas HEDG undergoes large-scale wear later in the process due to increased grinding forces.The surface roughness(R_(a))characteristics of UVHEDG are superior,with the average value of R_(a)decreasing by 46.5%compared to HEDG as MRV increases.The surface morphology in UVHEDG exhibits enhanced smoothness and a shallower layer of plastic deformation.Grinding chips generated by UVHEDG show a more shear-like shape,with the applied influence of ultrasonic vibration on chip morphology,thereby impacting material removal behaviors.These aforementioned findings contribute to enhanced machining efficiency and product quality ofγ-TiAl alloys after employing ultrasonic vibrations into HEDG.
基金Funded by Joint Funds of the National Natural Science Foundation of China(No.U1904188)the Jiangxi Provincial Department of Education Science and Technology Project(Nos.GJJ171079,GJJ181023,and GJJ181022)。
文摘To solve the problem of only surface carbonation and realize high-efficiency carbonation of recycled coarse aggregate,the method of carbonated recycled coarse aggregate with nano materials pre-soaking was first put forward.The carbonation effect of modified recycled coarse aggregate with three different carbonation methods was evaluated,and water absorption,apparent density and crush index of modified recycled coarse aggregate were measured.Combined with XRD,SEM,and MIP microscopic analysis,the high-efficiency carbonation strengthening mechanism of modified recycled coarse aggregate was revealed.The experimental results show that,compared with the non-carbonated recycled coarse aggregate,the physical and microscopic properties of carbonated recycled coarse aggregate are improved.The method of carbonation with nano-SiO_(2) pre-soaking can realize the high-efficiency carbonation of recycled coarse aggregate,for modified recycled coarse aggregate with the method,water absorption is reduced by 23.03%,porosity is reduced by 44.06%,and the average pore diameter is 21.82 nm.The high-efficiency carbonation strengthening mechanism show that the pre-socked nano-SiO_(2) is bound to the hydration product Ca(OH)_(2) of the old mortar with nano-scale C-S-H,which can improve the CO_(2) absorption rate,accelerate the carbonation reaction,generate more stable CaCO_(3) and nano-scale silica gel,and bond to the dense three-dimensional network structure to realize the bidirectional enhancement of nano-materials and pressurized carbonation.It is concluded that the method of carbonation with nano-SiO_(2) pre-soaking is a novel high-efficiency carbonation modification of recycled coarse aggregate.
基金support from the National Natural Science Foundation of China(Grant Nos.52025028,52332008,52372214,and U22A20137)the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions.
文摘Metal halide perovskite solar cells(PSCs)are one of the most promising photovoltaic devices.Over time,many strategies have been adopted to improve PSC efficiency,and the certified efficiency has reached 26.1%.However,only a few research groups have fabricated PSCs with an efficiency of>25%,indicating that achieving this efficiency remains uncommon.To develop the PSC industry,outstanding talent must be reserved with the latest technologies.Herein,we summarize the recent developments in high-efficiency PSCs(>25%)and highlight their effective strategies in crystal regulation,interface passivation,and component layer structural design.Finally,we propose perspectives based on current research to further enhance the efficiency and promote the commercialization process of PSCs.
