Cloud storage and edge computing are utilized to address the storage and computational challenges arising from the exponential data growth in IoT.However,data privacy is potentially risky when data is outsourced to cl...Cloud storage and edge computing are utilized to address the storage and computational challenges arising from the exponential data growth in IoT.However,data privacy is potentially risky when data is outsourced to cloud servers or edge services.While data encryption ensures data confidentiality,it can impede data sharing and retrieval.Attribute-based searchable encryption(ABSE)is proposed as an effective technique for enhancing data security and privacy.Nevertheless,ABSE has its limitations,such as single attribute authorization failure,privacy leakage during the search process,and high decryption overhead.This paper presents a novel approach called the blockchain-assisted efficientmulti-authority attribute-based searchable encryption scheme(BEM-ABSE)for cloudedge collaboration scenarios to address these issues.BEM-ABSE leverages a consortium blockchain to replace the central authentication center for global public parameter management.It incorporates smart contracts to facilitate reliable and fair ciphertext keyword search and decryption result verification.To minimize the computing burden on resource-constrained devices,BEM-ABSE adopts an online/offline hybrid mechanism during the encryption process and a verifiable edge-assisted decryption mechanism.This ensures both low computation cost and reliable ciphertext.Security analysis conducted under the random oracle model demonstrates that BEM-ABSE is resistant to indistinguishable chosen keyword attacks(IND-CKA)and indistinguishable chosen plaintext attacks(INDCPA).Theoretical analysis and simulation results confirm that BEM-ABSE significantly improves computational efficiency compared to existing solutions.展开更多
The Qilian Orogen Zone(QOZ), located in the north margin of the Tibetan Plateau, is the key area for understanding the deformation and dynamics process of Tibet. Numerous geological and geophysical studies have been c...The Qilian Orogen Zone(QOZ), located in the north margin of the Tibetan Plateau, is the key area for understanding the deformation and dynamics process of Tibet. Numerous geological and geophysical studies have been carried out on the mechanics of the Tibetan Plateau deformation and uplift; however, the detailed structure and deformation style of the Qilian Orogen Zone have remained uncertain due to poor geophysical data coverage and limited resolution power of inversion algorithms. In this study, we analyze the P-wave velocity structure beneath the Qilian Orogen Zone, obtained by applying multi-scale seismic tomography technique to P-wave arrival time data recorded by regional seismic networks. The seismic tomography algorithm used in this study employs sparsity constraints on the wavelet representation of the velocity model via L1-norm regularization. This algorithm can deal efficiently with uneven-sampled volumes, and can obtain multi-scale images of the velocity model. Our results can be summarized as follows:(1) The crustal velocity structure is strongly inhomogeneous and consistent with the surface geological setting. Significant low-velocity anomalies exist in the crust of northeastern Tibet, and slight high-velocity anomalies exist beneath the Qaidam Basin and Alxa terrane.(2)The Qilian Orogen Zone can be divided into two main parts by the Laji Shan Faults: the northwestern part with a low-velocity feature, and the southeastern part with a high-velocity feature at the upper and middle crust.(3) Our tomographic images suggest that northwestern and southeastern Qilian Orogen Zones have undergone different tectonic processes. In the northwest Qilian Orogen Zone, the deformation and growth of the Northern Tibetan Plateau has extended to the Heli Shan and Beida Shan region by northward overthrusting at the upper crust and thickening in the lower crust. We speculate that in the southeast Qilian Orogen Zone the deformation and growth of the Northern Tibet Plateau were of strike-slip style at the upper crust; in the lower crust, the evidence suggests ductile shear extrusion style and active frontage extension to the Alxa terrane.(4) The multi-scale seismic tomography technique provides multiscale analysis and sparse constraints, which has allowed to us obtain stable, high-resolution results.展开更多
Based on the experimental data from hot compression tests on Gleeble 1500 thermal simulator, the revised constitutive equations of spray-formed FGH95 superalloy considering the effect of strain on the material constan...Based on the experimental data from hot compression tests on Gleeble 1500 thermal simulator, the revised constitutive equations of spray-formed FGH95 superalloy considering the effect of strain on the material constants were established. The average absolute relative error （AARE） was employed to verify the validity of the constitutive equation, and the value of AARE is 3.85 %. Subsequently, the revised constitutive equations were successfully used to simulate and analyze the deformation behavior, stress distribution, forming loads and temperature distribution in both dies and billet during the isothermal forging process of turbine disk of large dimension （about 400 mm in diameter） by the means of finite element method （FEM）. Moreover, the optimum process parameters are 1,120 ℃ of forging temperature and 0.01 s^-1 of strain rate for the spray-formed FGH95 superalloy turbine disk.展开更多
A greater number of compact and reliable electrostatic capacitors are in demand due to the Internet of Things boom and rapidly growing complex and integrated electronic systems,continuously promoting the development o...A greater number of compact and reliable electrostatic capacitors are in demand due to the Internet of Things boom and rapidly growing complex and integrated electronic systems,continuously promoting the development of high-energy-density ceramic-based capacitors.Although significant successes have been achieved in obtaining high energy densities in lead-based ferroelectric ceramics,the utilization of lead-containing ceramies has been restricted due to environmental and health hazards of lead.Lead-free ferroelectric ceramics have garnered tremendous attention and are expected to replace lead-based ceramics in the near future.However,the energy density of lead-free ceramics is still lagging behind that of lead-containing cou.nterparts,severely limiting their applications.Significant efforts have been made to enhance the energy storage performance of lead-free ceramics using multi-scale design strategies,and exciting progress has been achieved in the past decade.This review briefly discusses the energy storage mechanism and fundamental characteristics of a dielectric capacitor,summarizes and compares the state-of-the-art design strategies for high-energy-density lead-free ceramics,and highlights several critical issues and requirements for industrial production.The prospects and challenges of lead-free ceramics for energy storage applications are also discussed.展开更多
To investigate the hot deformation behavior of powder-forged （P/F） Fe-0. 5C：-2Cu steel, the hot compres- sion tests were conducted at temperatures ranging from 900 to 1000 ℃ and strain rates from 0.1 to 10 s-1 usi...To investigate the hot deformation behavior of powder-forged （P/F） Fe-0. 5C：-2Cu steel, the hot compres- sion tests were conducted at temperatures ranging from 900 to 1000 ℃ and strain rates from 0.1 to 10 s-1 using Gleeble-1500 thermal simulator. The true stress-true strain curves at different temperatures and strain rates of P/F steel were obtained. It is found that dynamic recovery only occurs as strain rate is 10 s 1 at 900 ℃, and the dynamic recrystallization is the main softening mechanism. The flow stress increases with decreasing temperature and increas- ing strain rate. The experimental data are employed to develop constitutive equations on the basis of the Arrhenius- type equation by introducing the strain with nonlinear fitting. The flow stresses prediel：ed by the proposed constitu- tive equations are in good agreement with the experimental values, and the correlation coefficient （R2） and the aver- age absolute relative error （AARE） are 0. 995 25 and 3.07% respectively. These results indicate the proposed consti- tutive equations can effectively describe the hot deformation behavior of the material.展开更多
Many crops in China have two or more harvesting methods;however,little research has focused on this phenomenon.The current study proposes an operational model that looks to maximize grower profits.This model considers...Many crops in China have two or more harvesting methods;however,little research has focused on this phenomenon.The current study proposes an operational model that looks to maximize grower profits.This model considers a production plan for a perishable crop that has two harvesting methods:harvesting unripe produce at a lower operational cost but with a long lead time,and harvesting ripe crops at a higher operational cost but with quick turnaround.This study proposes a heuristic algorithm by which to pinpoint the optimal plan for the model;the model results indicate that for a crop with two harvesting methods,significant savings can be obtained by applying an optimal production plan.The current study’s main contribution is a production model for crops that feature two harvesting methods and for which the market poses varying demands.展开更多
FeCrAl alloy is one of the most promising candidates as an accident-tolerant fuel(ATF)cladding material.Herein,the influence of cold-rolling(CR)reduction on microstructure and tensile properties of the as-annealed FeC...FeCrAl alloy is one of the most promising candidates as an accident-tolerant fuel(ATF)cladding material.Herein,the influence of cold-rolling(CR)reduction on microstructure and tensile properties of the as-annealed FeCrAl alloys,with low Cr and Nb contents,is systematically examined.With the increase in CR reduction,the grain size of FeCrAl alloy is obviously refined after annealing because the increase in stored deformation energy leads to enhanced recrystallization.However,the large CR reductions result in a severe mixed-grain microstructure,significantly reducing the uniform deformability of the FeCrAl alloy.The dislocation density of the as-annealed FeCrAl alloy decreases with the increase in CR reduction,except for the excessive CR reduction of 50%.Moreover,the Laves phases are crushed and dissolved during CR and annealing,as well as large amounts of refined Laves phases are found after large CR reductions.The pinning effect of the Laves phases can significantly improve the strength of FeCrAl alloy.Accordingly,the strengthening mechanisms of FeCrAl alloy consist of fine-grain strengthening,dislocation strengthening and precipitation strengthening.Finally,the FeCrAl alloy,with a CR reduction of 30%,achieves optimal tensile properties.This study can provide theoretical guidance for the industrial production of the FeCrAl alloy.展开更多
Perovskite quantum dots(PeQDs)are considered potential display materials due to their high color purity,high photoluminescence quantum yield(PLQY),low cost and easy film casting.In this work,a novel electroluminescenc...Perovskite quantum dots(PeQDs)are considered potential display materials due to their high color purity,high photoluminescence quantum yield(PLQY),low cost and easy film casting.In this work,a novel electroluminescence(EL)device consisting of the interface layer of long alkyl-based oleylammonium bromide(OAmBr),which passivates the surface defects of PeQDs and adjusts the carrier transport properties,was designed.The PLQY of the OAmBr/PeQD bilayer was significantly improved.A high-performance EL device with the structure of indium tin oxide/poly(3,4-ethylenedioxythiophene)polystyrene sulfonate/poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine)/OAmBr/PeQDs/2,2′,2′′-(1,3,5-benzinetriyl)-tris(1-phenyl-1H benzimidazole)/LiF/Al was constructed using a spin-coating method.A peak external quantum efficiency(EQE)of 16.5%at the emission wavelength of 646 nm was obtained.Furthermore,an efficient matrix EL device was fabricated using an inkjet printing method.A high-quality PeQD matrix film was obtained by introducing small amounts of polybutene into the PeQDs to improve the printing process.The EQE reached 9.6%for the matrix device with 120 pixels per inch and the same device structure as that of the spin-coating one.展开更多
基金supported by the National Natural Science Foundation of China(Nos.62162018,61972412)the Natural Science Foundation of Guangxi(No.2019GXNSFGA245004)+1 种基金the Guilin Science and Technology Project(20210226-1)the Innovation Project of Guangxi Graduate Education(No.YCSW2022296).
文摘Cloud storage and edge computing are utilized to address the storage and computational challenges arising from the exponential data growth in IoT.However,data privacy is potentially risky when data is outsourced to cloud servers or edge services.While data encryption ensures data confidentiality,it can impede data sharing and retrieval.Attribute-based searchable encryption(ABSE)is proposed as an effective technique for enhancing data security and privacy.Nevertheless,ABSE has its limitations,such as single attribute authorization failure,privacy leakage during the search process,and high decryption overhead.This paper presents a novel approach called the blockchain-assisted efficientmulti-authority attribute-based searchable encryption scheme(BEM-ABSE)for cloudedge collaboration scenarios to address these issues.BEM-ABSE leverages a consortium blockchain to replace the central authentication center for global public parameter management.It incorporates smart contracts to facilitate reliable and fair ciphertext keyword search and decryption result verification.To minimize the computing burden on resource-constrained devices,BEM-ABSE adopts an online/offline hybrid mechanism during the encryption process and a verifiable edge-assisted decryption mechanism.This ensures both low computation cost and reliable ciphertext.Security analysis conducted under the random oracle model demonstrates that BEM-ABSE is resistant to indistinguishable chosen keyword attacks(IND-CKA)and indistinguishable chosen plaintext attacks(INDCPA).Theoretical analysis and simulation results confirm that BEM-ABSE significantly improves computational efficiency compared to existing solutions.
基金supported by the National Natural Science Foundation of China(41574045,41590862)State Key Laboratory of Earthquake Dynamics(LED2013A06)
文摘The Qilian Orogen Zone(QOZ), located in the north margin of the Tibetan Plateau, is the key area for understanding the deformation and dynamics process of Tibet. Numerous geological and geophysical studies have been carried out on the mechanics of the Tibetan Plateau deformation and uplift; however, the detailed structure and deformation style of the Qilian Orogen Zone have remained uncertain due to poor geophysical data coverage and limited resolution power of inversion algorithms. In this study, we analyze the P-wave velocity structure beneath the Qilian Orogen Zone, obtained by applying multi-scale seismic tomography technique to P-wave arrival time data recorded by regional seismic networks. The seismic tomography algorithm used in this study employs sparsity constraints on the wavelet representation of the velocity model via L1-norm regularization. This algorithm can deal efficiently with uneven-sampled volumes, and can obtain multi-scale images of the velocity model. Our results can be summarized as follows:(1) The crustal velocity structure is strongly inhomogeneous and consistent with the surface geological setting. Significant low-velocity anomalies exist in the crust of northeastern Tibet, and slight high-velocity anomalies exist beneath the Qaidam Basin and Alxa terrane.(2)The Qilian Orogen Zone can be divided into two main parts by the Laji Shan Faults: the northwestern part with a low-velocity feature, and the southeastern part with a high-velocity feature at the upper and middle crust.(3) Our tomographic images suggest that northwestern and southeastern Qilian Orogen Zones have undergone different tectonic processes. In the northwest Qilian Orogen Zone, the deformation and growth of the Northern Tibetan Plateau has extended to the Heli Shan and Beida Shan region by northward overthrusting at the upper crust and thickening in the lower crust. We speculate that in the southeast Qilian Orogen Zone the deformation and growth of the Northern Tibet Plateau were of strike-slip style at the upper crust; in the lower crust, the evidence suggests ductile shear extrusion style and active frontage extension to the Alxa terrane.(4) The multi-scale seismic tomography technique provides multiscale analysis and sparse constraints, which has allowed to us obtain stable, high-resolution results.
基金financially supported by the National Natural Science Foundation of China(No.50974016).
文摘Based on the experimental data from hot compression tests on Gleeble 1500 thermal simulator, the revised constitutive equations of spray-formed FGH95 superalloy considering the effect of strain on the material constants were established. The average absolute relative error （AARE） was employed to verify the validity of the constitutive equation, and the value of AARE is 3.85 %. Subsequently, the revised constitutive equations were successfully used to simulate and analyze the deformation behavior, stress distribution, forming loads and temperature distribution in both dies and billet during the isothermal forging process of turbine disk of large dimension （about 400 mm in diameter） by the means of finite element method （FEM）. Moreover, the optimum process parameters are 1,120 ℃ of forging temperature and 0.01 s^-1 of strain rate for the spray-formed FGH95 superalloy turbine disk.
基金supported by the National Science Foundation of China(No.61631166004)Shenzhen Science and Technology Program(Grant Nos.KQTD20180411143514543 and JCYJ20180504165831308)Guangdong Provincial Key Laboratory Program(Grant No.2021B1212040001)。
文摘A greater number of compact and reliable electrostatic capacitors are in demand due to the Internet of Things boom and rapidly growing complex and integrated electronic systems,continuously promoting the development of high-energy-density ceramic-based capacitors.Although significant successes have been achieved in obtaining high energy densities in lead-based ferroelectric ceramics,the utilization of lead-containing ceramies has been restricted due to environmental and health hazards of lead.Lead-free ferroelectric ceramics have garnered tremendous attention and are expected to replace lead-based ceramics in the near future.However,the energy density of lead-free ceramics is still lagging behind that of lead-containing cou.nterparts,severely limiting their applications.Significant efforts have been made to enhance the energy storage performance of lead-free ceramics using multi-scale design strategies,and exciting progress has been achieved in the past decade.This review briefly discusses the energy storage mechanism and fundamental characteristics of a dielectric capacitor,summarizes and compares the state-of-the-art design strategies for high-energy-density lead-free ceramics,and highlights several critical issues and requirements for industrial production.The prospects and challenges of lead-free ceramics for energy storage applications are also discussed.
基金the support received from Suzhou Kunlun Advanced Manufacturing Technologies and Equipment Co.,Ltd
文摘To investigate the hot deformation behavior of powder-forged （P/F） Fe-0. 5C：-2Cu steel, the hot compres- sion tests were conducted at temperatures ranging from 900 to 1000 ℃ and strain rates from 0.1 to 10 s-1 using Gleeble-1500 thermal simulator. The true stress-true strain curves at different temperatures and strain rates of P/F steel were obtained. It is found that dynamic recovery only occurs as strain rate is 10 s 1 at 900 ℃, and the dynamic recrystallization is the main softening mechanism. The flow stress increases with decreasing temperature and increas- ing strain rate. The experimental data are employed to develop constitutive equations on the basis of the Arrhenius- type equation by introducing the strain with nonlinear fitting. The flow stresses prediel：ed by the proposed constitu- tive equations are in good agreement with the experimental values, and the correlation coefficient （R2） and the aver- age absolute relative error （AARE） are 0. 995 25 and 3.07% respectively. These results indicate the proposed consti- tutive equations can effectively describe the hot deformation behavior of the material.
基金This researchwas supported by:(i)MOE(Ministry of Education in China)Liberal Arts and Social Sciences Foundation(18YJC630070)(ii)Nanjing Agricultural University Fundamental Research Funds for the Central Universities(SKYZ2018031).
文摘Many crops in China have two or more harvesting methods;however,little research has focused on this phenomenon.The current study proposes an operational model that looks to maximize grower profits.This model considers a production plan for a perishable crop that has two harvesting methods:harvesting unripe produce at a lower operational cost but with a long lead time,and harvesting ripe crops at a higher operational cost but with quick turnaround.This study proposes a heuristic algorithm by which to pinpoint the optimal plan for the model;the model results indicate that for a crop with two harvesting methods,significant savings can be obtained by applying an optimal production plan.The current study’s main contribution is a production model for crops that feature two harvesting methods and for which the market poses varying demands.
基金financially supported by the National Natural Science Foundation of China(No.52122103)the Sichuan Science and Technology Program(No.2022YFG0346).
文摘FeCrAl alloy is one of the most promising candidates as an accident-tolerant fuel(ATF)cladding material.Herein,the influence of cold-rolling(CR)reduction on microstructure and tensile properties of the as-annealed FeCrAl alloys,with low Cr and Nb contents,is systematically examined.With the increase in CR reduction,the grain size of FeCrAl alloy is obviously refined after annealing because the increase in stored deformation energy leads to enhanced recrystallization.However,the large CR reductions result in a severe mixed-grain microstructure,significantly reducing the uniform deformability of the FeCrAl alloy.The dislocation density of the as-annealed FeCrAl alloy decreases with the increase in CR reduction,except for the excessive CR reduction of 50%.Moreover,the Laves phases are crushed and dissolved during CR and annealing,as well as large amounts of refined Laves phases are found after large CR reductions.The pinning effect of the Laves phases can significantly improve the strength of FeCrAl alloy.Accordingly,the strengthening mechanisms of FeCrAl alloy consist of fine-grain strengthening,dislocation strengthening and precipitation strengthening.Finally,the FeCrAl alloy,with a CR reduction of 30%,achieves optimal tensile properties.This study can provide theoretical guidance for the industrial production of the FeCrAl alloy.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.22090024,51521002 and 62074059)the Basic and Applied Basic Research Major Program of Guangdong Province(Grant No.2019B030302007).
文摘Perovskite quantum dots(PeQDs)are considered potential display materials due to their high color purity,high photoluminescence quantum yield(PLQY),low cost and easy film casting.In this work,a novel electroluminescence(EL)device consisting of the interface layer of long alkyl-based oleylammonium bromide(OAmBr),which passivates the surface defects of PeQDs and adjusts the carrier transport properties,was designed.The PLQY of the OAmBr/PeQD bilayer was significantly improved.A high-performance EL device with the structure of indium tin oxide/poly(3,4-ethylenedioxythiophene)polystyrene sulfonate/poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine)/OAmBr/PeQDs/2,2′,2′′-(1,3,5-benzinetriyl)-tris(1-phenyl-1H benzimidazole)/LiF/Al was constructed using a spin-coating method.A peak external quantum efficiency(EQE)of 16.5%at the emission wavelength of 646 nm was obtained.Furthermore,an efficient matrix EL device was fabricated using an inkjet printing method.A high-quality PeQD matrix film was obtained by introducing small amounts of polybutene into the PeQDs to improve the printing process.The EQE reached 9.6%for the matrix device with 120 pixels per inch and the same device structure as that of the spin-coating one.
