The Nd:TiO_(2 )PEO coatings were formed in a phosphate-based electrolyte with the addition of Nd_(2)O_(3 )under the current density of 150,200,250 and 300 m A/cm^(2).SEM results showed that the micropores decreased on...The Nd:TiO_(2 )PEO coatings were formed in a phosphate-based electrolyte with the addition of Nd_(2)O_(3 )under the current density of 150,200,250 and 300 m A/cm^(2).SEM results showed that the micropores decreased on quantity and increased on scale with the increasing current density.AFM results revealed that the roughness of the coatings increased with the increasing current density.Phase and composition analysis showed that the Nd:TiO_(2) coatings were mainly composed of anatase and rutile phase.And the anatase phase content has reached the maximum value at the current density of 250 m A/cm^(2).XPS results indicated that Ti2p spin-orbit components of the Nd:TiO_(2) coatings are shifted towards higher binding energy,compared with the pure TiO_(2) coating,suggesting that some of the Nd^(3+)ions are combined with TiO_(2) lattice and led to dislocation.Photocatalytic test showed that the photocatalytic activity of Nd:TiO_(2) coatings varied in the same pattern with the anatase content variation in Nd:TiO_(2) coatings.The photocatalytic experiment results show that the photocatalytic activity of Nd:TiO_(2) coatings can be greatly enhanced with moderate amount of Nd^(3+).However,excessive amount of Nd^(3+)does not have an effective impact on the photoctalytic activity improvement.展开更多
This paper proposed an efficient research method for high-dimensional uncertainty quantification of projectile motion in the barrel of a truck-mounted howitzer.Firstly,the dynamic model of projectile motion is establi...This paper proposed an efficient research method for high-dimensional uncertainty quantification of projectile motion in the barrel of a truck-mounted howitzer.Firstly,the dynamic model of projectile motion is established considering the flexible deformation of the barrel and the interaction between the projectile and the barrel.Subsequently,the accuracy of the dynamic model is verified based on the external ballistic projectile attitude test platform.Furthermore,the probability density evolution method(PDEM)is developed to high-dimensional uncertainty quantification of projectile motion.The engineering example highlights the results of the proposed method are consistent with the results obtained by the Monte Carlo Simulation(MCS).Finally,the influence of parameter uncertainty on the projectile disturbance at muzzle under different working conditions is analyzed.The results show that the disturbance of the pitch angular,pitch angular velocity and pitch angular of velocity decreases with the increase of launching angle,and the random parameter ranges of both the projectile and coupling model have similar influence on the disturbance of projectile angular motion at muzzle.展开更多
Aviation accidents are currently one of the leading causes of significant injuries and deaths worldwide. This entices researchers to investigate aircraft safety using data analysis approaches based on an advanced mach...Aviation accidents are currently one of the leading causes of significant injuries and deaths worldwide. This entices researchers to investigate aircraft safety using data analysis approaches based on an advanced machine learning algorithm.To assess aviation safety and identify the causes of incidents, a classification model with light gradient boosting machine (LGBM)based on the aviation safety reporting system (ASRS) has been developed. It is improved by k-fold cross-validation with hybrid sampling model (HSCV), which may boost classification performance and maintain data balance. The results show that employing the LGBM-HSCV model can significantly improve accuracy while alleviating data imbalance. Vertical comparison with other cross-validation (CV) methods and lateral comparison with different fold times comprise the comparative approach. Aside from the comparison, two further CV approaches based on the improved method in this study are discussed:one with a different sampling and folding order, and the other with more CV. According to the assessment indices with different methods, the LGBMHSCV model proposed here is effective at detecting incident causes. The improved model for imbalanced data categorization proposed may serve as a point of reference for similar data processing, and the model’s accurate identification of civil aviation incident causes can assist to improve civil aviation safety.展开更多
The 2024 anodized aluminum alloy film was sealed by KAl(SO_(4))_(2)solution and the effect of sealing on corrosion resistance was investigated by means of potentiodynamic polarization curves,electrochemical impedance ...The 2024 anodized aluminum alloy film was sealed by KAl(SO_(4))_(2)solution and the effect of sealing on corrosion resistance was investigated by means of potentiodynamic polarization curves,electrochemical impedance spectroscopy,and X-ray photoelectron spectroscopy.The experimental results show that the optimal parameters for KAl(SO_(4))_(2)sealing are 35℃,with the pH value of 8,the concentration of 8 g/L,and the sealing time of 3 min.The corrosion resistance of the KAl(SO_(4))_(2)sealed sample can be significantly improved than that of unsealed one,and is obviously superior to that of the conventional hydrothermal sealed sample.Furthermore,X-ray photoelectron spectroscopy demonstrates that more Al(OH)_(3)will be formed in the process of KAl(SO_(4))_(2)sealing,which will shrink the diameter of the microporous and therefore results in the excellent corrosion resistance.展开更多
Plasma electrolytic oxidation(PEO)coatings were formed on 7075 aluminum alloy in silicate-borate based electrolyte with different duty cycles.The physical and chemical properties of the PEO coatings were thoroughly in...Plasma electrolytic oxidation(PEO)coatings were formed on 7075 aluminum alloy in silicate-borate based electrolyte with different duty cycles.The physical and chemical properties of the PEO coatings were thoroughly investigated.The wearing and corrosion properties of the coatings were evaluated by wearing experiments and potentiodynamic polarization tests,respectively.The results showed that the micro-hardness of the coatings first increased and then decreased with the increasing duty cycle.As a results,the wearing resistance of the coatings first increased and then decreased with the increasing duty cycle.Composition analysis proved that the coatings were mainly composed ofα-Al_(2)O_(3)andγ-Al_(2)O_(3).The presence of wear scars on the worn surface morphology demonstrates that the three-body rolling was the main wear mechanism for coated specimen.The corrosion study showed that the coating formed in the mixed electrolyte with duty cycle of 80%showed the most superior corrosion resistance.展开更多
The grain boundary(GB)damage of long-term crept HR3C(25Cr–20Ni–Nb–N)austenitic steel with solid solution state was investigated by nanoindentation test accompanied with in-situ electron back-scattered diffraction.T...The grain boundary(GB)damage of long-term crept HR3C(25Cr–20Ni–Nb–N)austenitic steel with solid solution state was investigated by nanoindentation test accompanied with in-situ electron back-scattered diffraction.The corresponding microstructure was characterized by scanning electron microscopy and transmission electron microscopy.Results show that the increase in nanoindentation hardness at the GBs and triple grain junctions may be related to the dislocation accumulation and carbide growth during the creep.Coarsened M23C6 and dislocations piling-up at the GB accelerate the nucleation and coalescence of creep cavity along the GB.The nanoindentation hardness in grains varies with orientation of the stress axis.The orientation difference of neighbor grains may induce local high geometrically necessary dislocation densities and strain gradients near the GB,consequently causing stress concentration and subsequent crack growth at specific GBs.展开更多
The photonic spin Hall effect(PSHE),characterized by two splitting beams with opposite spins,has great potential applications in nano-photonic devices,optical sensing fields,and precision metrology.We present the sign...The photonic spin Hall effect(PSHE),characterized by two splitting beams with opposite spins,has great potential applications in nano-photonic devices,optical sensing fields,and precision metrology.We present the significant enhancement of terahertz(THz)PSHE by taking advantage of the optical Tamm state(OTS)in In Sb-distributed Bragg reflector(DBR)structure.The spin shift of reflected light can be dynamically tuned by the structural parameters(e.g.the thickness)of the InSb-DBR structure as well as the temperature,and the maximum spin shift for a horizontally polarized incident beam at 1.1 THz can reach up to 11.15 mm.Moreover,we propose a THz gas sensing device based on the enhanced PSHE via the strong excitation of OTS for the InSb-DBR structure with a superior intensity sensitivity of 5.873×10^(4)mm/RIU and good stability.This sensor exhibits two orders of magnitude improvement compared with the similar PSHE sensor based on In Sb-supported THz long-range surface plasmon resonance.These findings may provide an alternative way for the enhanced PSHE and offer the opportunity for developing new optical sensing devices.展开更多
The effects of the content of rare earth elements on the microstructure and properties of hot-dip Zn-5 Al alloy steel wire for bridge cables were investigated.The microstructure of the hot-dip coating was analyzed usi...The effects of the content of rare earth elements on the microstructure and properties of hot-dip Zn-5 Al alloy steel wire for bridge cables were investigated.The microstructure of the hot-dip coating was analyzed using an optical microscope and a scanning electron microscope equipped with an energy-dispersive spectrometer.The bonding force between the hot-dip coating and steel wire was determined by the winding test.The corrosion resistance of the steel wire hot-dip coating was tested by the electrochemical workstation.The hot-dip Zn-5A1 alloy coating has a corrosion-resistant structure composed of a zinc-rich phase and an aluminum-rich phase.Due to the enhanced bonding force,the micro structure of the hot-dip coating of the Zn-5A1 alloy with rare earth elements is more compact and uniform than that without rare earth elements.The addition of rare earth elements improves the corrosion resistance of Zn-5A1 alloy coated steel wire.Due to the rare earth segregation,which prevents the corrosion of the grain boundary and enhances the anti-intergranular corrosion performance,steel wire exhibits the optimum corrosion resistance when the content of rare earth elements is 0.08 wt.%.展开更多
Although forbidden band effect in perfectly periodic phononic crystals(PC)is very attractive,random disordered(i.e.detuning)phenomenon is inevitable in engineering processing,thus explor-ing the effect of detuning on ...Although forbidden band effect in perfectly periodic phononic crystals(PC)is very attractive,random disordered(i.e.detuning)phenomenon is inevitable in engineering processing,thus explor-ing the effect of detuning on the wave characteristics of PC becomes a necessity.In this study,fundamental governing equa-tions and boundary conditions are derived from the principle of virtual work.Wave characteristics and localization factor of one-dimensional(1D)detuned nano-PC are investigated based on the transfer matrix method,with flexoelectric effect duly accounted for.Subsequently,with BaTiO_(3)SrTiO_(3) nano-PC taken for illustration,forbidden band properties and localization factor of 1D elastic waves in harmonic and detuned states are systematically character-ized.It is demonstrated that localization factor can characterize the energy band structure of 1D PC perfectly.Flexoelectric effect tends to widen the width of forbidden band with increasing detuning,and detuning is linearly related to the bandwidth.The forbidden band is more sensitive to flexoelectric coefficient detuning than thickness detuning.The research results provide useful theoretical guidance for designing high-frequency nanoscaled devices with the function of filtering based on band gap effect of nano-PC.展开更多
This study systematically investigated the influence of the microstructure evolution,mechanical properties and corrosion behaviors on Zn–1.5Mg(wt%)alloy processed by room-temperature rolling.The as-cast Zn–1.5Mg all...This study systematically investigated the influence of the microstructure evolution,mechanical properties and corrosion behaviors on Zn–1.5Mg(wt%)alloy processed by room-temperature rolling.The as-cast Zn–1.5Mg alloy consists ofη-Zn matrix andη-Zn+Mg_(2)Zn_(11)eutectic structure.As rolling reduction increases,the average grain size of the alloy reduces from 42.9 to 1.7μm,and the eutectic structure undergoes fragmentation and refinement,changing from a network distribution surrounding the matrix to a lamellar alternating distribution with the matrix.The ultimate tensile strength of the as-rolled alloy(80%reduction)is increased to 366±3.7 MPa,along with a good elongation of 18.4%±2.0%.Immersion tests in Hanks’solution indicate that the initial corrosion rate of the 80%-rolled alloy is 0.030 mm/year and finally stabilizes at 0.034 mm/year when the immersion duration is extended to 21 days.According to X-ray diffractometer and X-ray photoelectron spectroscopy analyses,Ca_(3)(PO_(4))_(2),CaCO_(3),Ca(OH)_(2),Zn_(3)(PO_(4))_(2),Zn(OH)_(2),ZnO and a small amount of MgO and MgCO_(3)are the main corrosion products on the surface.Due to the microstructure refinement,the developed alloy exhibits uniform corrosion,and the corrosion morphology is dominated by pitting pits.展开更多
In the design of conjugated molecules,modular production enables materials to easily realize structure modification and precisely tune their photoelectrical property.Construction of a novel and universal building bloc...In the design of conjugated molecules,modular production enables materials to easily realize structure modification and precisely tune their photoelectrical property.Construction of a novel and universal building block is crucial to design and manufacture high performance and stable conjugated molecules for optoelectronic application.Herein,we originally demonstrated a universal 4-qualifiable fluorene-based building block,which is a fundamental molecular segment to functionalize and obtain novel conjugated materials.Compared to the traditional modification at 9-site,additional 4-position functionalization provided an exciting blueprint to not only tune electronic structure and excited state via p-n molecular design engineering and space charge-transfer strategy,but also allow for optimizing intermolecular arrangement and obtaining solution-processing ability.The introduction of the 4-site substituent in fluorene based semiconductors may endow materials with unique properties.Finally,we successfully prepared two stable deep-blue light-emitting conjugated polymer,PODOPF and PODOF,by utilizing the 4-substituent fluorene based building block.It is believable that the performance,stability and processibility of reported outstanding fluorene-based conjugated molecules can be further optimized based on this universal building block.展开更多
Mobile edge computing(MEC) networks can provide a variety of services for different applications. End-to-end performance analysis of these services serves as a benchmark for the efficient planning of network resource ...Mobile edge computing(MEC) networks can provide a variety of services for different applications. End-to-end performance analysis of these services serves as a benchmark for the efficient planning of network resource allocation and routing strategies. In this paper, a performance analysis framework is proposed for the end-to-end data-flows in MEC networks based on stochastic network calculus(SNC). Due to the random nature of routing in MEC networks, probability parameters are introduced in the proposed analysis model to characterize this randomness into the derived expressions. Taking actual communication scenarios into consideration, the end-to-end performance of three network data-flows is analyzed, namely, voice over Internet protocol(VoIP), video, and file transfer protocol(FTP). These network data-flows adopt the preemptive priority scheduling scheme. Based on the arrival processes of these three data-flows, the effect of interference on their performances and the service capacity of each node in the MEC networks, closed-form expressions are derived for showing the relationship between delay, backlog upper bounds, and violation probability of the data-flows. Analytical and simulation results show that delay and backlog performances of the data-flows are influenced by the number of hops in the network and the random probability parameters of interference-flow(IF).展开更多
基金Supported by the Open Project Foundation of Industrial Perception and Intelligent Manufacturing Equipment Engineering Research Center of Jiangsu Province (No. ZK220504)the Open Project Foundation of High-tech Key Laboratory of Agricultural Equipment and Intelligence of Jiangsu Province (No. MAET202104)+1 种基金the Open Project Foundation of Jiangsu Wind Power Engineering Technology Center (No. ZK220302)the Qing Lan Project of Jiangsu Province,China。
文摘The Nd:TiO_(2 )PEO coatings were formed in a phosphate-based electrolyte with the addition of Nd_(2)O_(3 )under the current density of 150,200,250 and 300 m A/cm^(2).SEM results showed that the micropores decreased on quantity and increased on scale with the increasing current density.AFM results revealed that the roughness of the coatings increased with the increasing current density.Phase and composition analysis showed that the Nd:TiO_(2) coatings were mainly composed of anatase and rutile phase.And the anatase phase content has reached the maximum value at the current density of 250 m A/cm^(2).XPS results indicated that Ti2p spin-orbit components of the Nd:TiO_(2) coatings are shifted towards higher binding energy,compared with the pure TiO_(2) coating,suggesting that some of the Nd^(3+)ions are combined with TiO_(2) lattice and led to dislocation.Photocatalytic test showed that the photocatalytic activity of Nd:TiO_(2) coatings varied in the same pattern with the anatase content variation in Nd:TiO_(2) coatings.The photocatalytic experiment results show that the photocatalytic activity of Nd:TiO_(2) coatings can be greatly enhanced with moderate amount of Nd^(3+).However,excessive amount of Nd^(3+)does not have an effective impact on the photoctalytic activity improvement.
基金the National Natural Science Foundation of China(Grant No.11472137).
文摘This paper proposed an efficient research method for high-dimensional uncertainty quantification of projectile motion in the barrel of a truck-mounted howitzer.Firstly,the dynamic model of projectile motion is established considering the flexible deformation of the barrel and the interaction between the projectile and the barrel.Subsequently,the accuracy of the dynamic model is verified based on the external ballistic projectile attitude test platform.Furthermore,the probability density evolution method(PDEM)is developed to high-dimensional uncertainty quantification of projectile motion.The engineering example highlights the results of the proposed method are consistent with the results obtained by the Monte Carlo Simulation(MCS).Finally,the influence of parameter uncertainty on the projectile disturbance at muzzle under different working conditions is analyzed.The results show that the disturbance of the pitch angular,pitch angular velocity and pitch angular of velocity decreases with the increase of launching angle,and the random parameter ranges of both the projectile and coupling model have similar influence on the disturbance of projectile angular motion at muzzle.
基金supported by the National Natural Science Foundation of China Civil Aviation Joint Fund (U1833110)Research on the Dual Prevention Mechanism and Intelligent Management Technology f or Civil Aviation Safety Risks (YK23-03-05)。
文摘Aviation accidents are currently one of the leading causes of significant injuries and deaths worldwide. This entices researchers to investigate aircraft safety using data analysis approaches based on an advanced machine learning algorithm.To assess aviation safety and identify the causes of incidents, a classification model with light gradient boosting machine (LGBM)based on the aviation safety reporting system (ASRS) has been developed. It is improved by k-fold cross-validation with hybrid sampling model (HSCV), which may boost classification performance and maintain data balance. The results show that employing the LGBM-HSCV model can significantly improve accuracy while alleviating data imbalance. Vertical comparison with other cross-validation (CV) methods and lateral comparison with different fold times comprise the comparative approach. Aside from the comparison, two further CV approaches based on the improved method in this study are discussed:one with a different sampling and folding order, and the other with more CV. According to the assessment indices with different methods, the LGBMHSCV model proposed here is effective at detecting incident causes. The improved model for imbalanced data categorization proposed may serve as a point of reference for similar data processing, and the model’s accurate identification of civil aviation incident causes can assist to improve civil aviation safety.
基金Funded by the National Natural Science Foundation of China(No.12175107)the Natural Science Foundation of Nanjing University of Posts and Telecommunications(No.NY220030)
文摘The 2024 anodized aluminum alloy film was sealed by KAl(SO_(4))_(2)solution and the effect of sealing on corrosion resistance was investigated by means of potentiodynamic polarization curves,electrochemical impedance spectroscopy,and X-ray photoelectron spectroscopy.The experimental results show that the optimal parameters for KAl(SO_(4))_(2)sealing are 35℃,with the pH value of 8,the concentration of 8 g/L,and the sealing time of 3 min.The corrosion resistance of the KAl(SO_(4))_(2)sealed sample can be significantly improved than that of unsealed one,and is obviously superior to that of the conventional hydrothermal sealed sample.Furthermore,X-ray photoelectron spectroscopy demonstrates that more Al(OH)_(3)will be formed in the process of KAl(SO_(4))_(2)sealing,which will shrink the diameter of the microporous and therefore results in the excellent corrosion resistance.
基金Funded by the National Natural Science Foundation of China(No.11802117)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.19KJB430024)the Science Foundation of the Jiangsu Industrial Software Engineering Research Center(No.ZK190401)。
文摘Plasma electrolytic oxidation(PEO)coatings were formed on 7075 aluminum alloy in silicate-borate based electrolyte with different duty cycles.The physical and chemical properties of the PEO coatings were thoroughly investigated.The wearing and corrosion properties of the coatings were evaluated by wearing experiments and potentiodynamic polarization tests,respectively.The results showed that the micro-hardness of the coatings first increased and then decreased with the increasing duty cycle.As a results,the wearing resistance of the coatings first increased and then decreased with the increasing duty cycle.Composition analysis proved that the coatings were mainly composed ofα-Al_(2)O_(3)andγ-Al_(2)O_(3).The presence of wear scars on the worn surface morphology demonstrates that the three-body rolling was the main wear mechanism for coated specimen.The corrosion study showed that the coating formed in the mixed electrolyte with duty cycle of 80%showed the most superior corrosion resistance.
基金grateful for the financial support from the National Natural Science Foundation of China(51904156,51971163 and 51705082)the Open Fund of Jiangsu Wind Power Engineering Technology Center(ZK22-03-02)the Ten thousand talents project of Zhejiang Province(2019R52056).
文摘The grain boundary(GB)damage of long-term crept HR3C(25Cr–20Ni–Nb–N)austenitic steel with solid solution state was investigated by nanoindentation test accompanied with in-situ electron back-scattered diffraction.The corresponding microstructure was characterized by scanning electron microscopy and transmission electron microscopy.Results show that the increase in nanoindentation hardness at the GBs and triple grain junctions may be related to the dislocation accumulation and carbide growth during the creep.Coarsened M23C6 and dislocations piling-up at the GB accelerate the nucleation and coalescence of creep cavity along the GB.The nanoindentation hardness in grains varies with orientation of the stress axis.The orientation difference of neighbor grains may induce local high geometrically necessary dislocation densities and strain gradients near the GB,consequently causing stress concentration and subsequent crack growth at specific GBs.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12175107 and 12004194)the Natural Science Foundation of Nanjing University of Posts and Telecommunications(Grant No.NY220030)
文摘The photonic spin Hall effect(PSHE),characterized by two splitting beams with opposite spins,has great potential applications in nano-photonic devices,optical sensing fields,and precision metrology.We present the significant enhancement of terahertz(THz)PSHE by taking advantage of the optical Tamm state(OTS)in In Sb-distributed Bragg reflector(DBR)structure.The spin shift of reflected light can be dynamically tuned by the structural parameters(e.g.the thickness)of the InSb-DBR structure as well as the temperature,and the maximum spin shift for a horizontally polarized incident beam at 1.1 THz can reach up to 11.15 mm.Moreover,we propose a THz gas sensing device based on the enhanced PSHE via the strong excitation of OTS for the InSb-DBR structure with a superior intensity sensitivity of 5.873×10^(4)mm/RIU and good stability.This sensor exhibits two orders of magnitude improvement compared with the similar PSHE sensor based on In Sb-supported THz long-range surface plasmon resonance.These findings may provide an alternative way for the enhanced PSHE and offer the opportunity for developing new optical sensing devices.
基金The authors would like to acknowledge the support from Key-Area Research and Development Program of Guangdong Province(2019B111106002)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(21KJB460023).
文摘The effects of the content of rare earth elements on the microstructure and properties of hot-dip Zn-5 Al alloy steel wire for bridge cables were investigated.The microstructure of the hot-dip coating was analyzed using an optical microscope and a scanning electron microscope equipped with an energy-dispersive spectrometer.The bonding force between the hot-dip coating and steel wire was determined by the winding test.The corrosion resistance of the steel wire hot-dip coating was tested by the electrochemical workstation.The hot-dip Zn-5A1 alloy coating has a corrosion-resistant structure composed of a zinc-rich phase and an aluminum-rich phase.Due to the enhanced bonding force,the micro structure of the hot-dip coating of the Zn-5A1 alloy with rare earth elements is more compact and uniform than that without rare earth elements.The addition of rare earth elements improves the corrosion resistance of Zn-5A1 alloy coated steel wire.Due to the rare earth segregation,which prevents the corrosion of the grain boundary and enhances the anti-intergranular corrosion performance,steel wire exhibits the optimum corrosion resistance when the content of rare earth elements is 0.08 wt.%.
基金This work is supported by the National Natural Science Foundation of China(11502110,11972185,and 12002156)the Open Fund of the State Key Laboratory for Strength and Vibration of Mechanical Structures,Xi’an Jiaotong University(No.SV2018-KF-01,No.SV2018-KF-22)the Open Project of Space Structure and Mechanism Technology Laboratory of China Aerospace Science and Technology Group Co.,Ltd.
文摘Although forbidden band effect in perfectly periodic phononic crystals(PC)is very attractive,random disordered(i.e.detuning)phenomenon is inevitable in engineering processing,thus explor-ing the effect of detuning on the wave characteristics of PC becomes a necessity.In this study,fundamental governing equa-tions and boundary conditions are derived from the principle of virtual work.Wave characteristics and localization factor of one-dimensional(1D)detuned nano-PC are investigated based on the transfer matrix method,with flexoelectric effect duly accounted for.Subsequently,with BaTiO_(3)SrTiO_(3) nano-PC taken for illustration,forbidden band properties and localization factor of 1D elastic waves in harmonic and detuned states are systematically character-ized.It is demonstrated that localization factor can characterize the energy band structure of 1D PC perfectly.Flexoelectric effect tends to widen the width of forbidden band with increasing detuning,and detuning is linearly related to the bandwidth.The forbidden band is more sensitive to flexoelectric coefficient detuning than thickness detuning.The research results provide useful theoretical guidance for designing high-frequency nanoscaled devices with the function of filtering based on band gap effect of nano-PC.
基金the Key Research and Development Program of Jiangsu Province(BE2021027)the Project on Excellent Postgraduate Dissertation of Hohai University(422003518)+2 种基金the Postgraduate Research&Practice Innovation Program of Jiangsu Province(SJCX23_0175)the Opening Project of Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology(ASMA202102)the Jiangsu Key Laboratory for Light Metal Alloys(LMA202101).
文摘This study systematically investigated the influence of the microstructure evolution,mechanical properties and corrosion behaviors on Zn–1.5Mg(wt%)alloy processed by room-temperature rolling.The as-cast Zn–1.5Mg alloy consists ofη-Zn matrix andη-Zn+Mg_(2)Zn_(11)eutectic structure.As rolling reduction increases,the average grain size of the alloy reduces from 42.9 to 1.7μm,and the eutectic structure undergoes fragmentation and refinement,changing from a network distribution surrounding the matrix to a lamellar alternating distribution with the matrix.The ultimate tensile strength of the as-rolled alloy(80%reduction)is increased to 366±3.7 MPa,along with a good elongation of 18.4%±2.0%.Immersion tests in Hanks’solution indicate that the initial corrosion rate of the 80%-rolled alloy is 0.030 mm/year and finally stabilizes at 0.034 mm/year when the immersion duration is extended to 21 days.According to X-ray diffractometer and X-ray photoelectron spectroscopy analyses,Ca_(3)(PO_(4))_(2),CaCO_(3),Ca(OH)_(2),Zn_(3)(PO_(4))_(2),Zn(OH)_(2),ZnO and a small amount of MgO and MgCO_(3)are the main corrosion products on the surface.Due to the microstructure refinement,the developed alloy exhibits uniform corrosion,and the corrosion morphology is dominated by pitting pits.
基金supported by the Natural Science Foundation of Jiangsu Province(No.BK20200700)National Natural Science Foundation of China(Nos.22075136,61874053)+4 种基金Natural Science Funds of the Education Committee of Jiangsu Province(No.18KJA430009)"High-Level Talents in Six Industries"of Jiangsu Province(No.XYDXX-019)Postgraduate Research&Practice Innovation Program of Jiangsu Province(Nos.KYCX21_1097,KYCX21_0771)Nanjing Vocational University of Industry Technology Start-up Fund(No.YK21-02-07)the open research fund from Anhui Province Key Laboratory of Environment-friendly Polymer Materials and Anhui Province Key Laboratory of Optoelectronic Materials Science and Technology.
文摘In the design of conjugated molecules,modular production enables materials to easily realize structure modification and precisely tune their photoelectrical property.Construction of a novel and universal building block is crucial to design and manufacture high performance and stable conjugated molecules for optoelectronic application.Herein,we originally demonstrated a universal 4-qualifiable fluorene-based building block,which is a fundamental molecular segment to functionalize and obtain novel conjugated materials.Compared to the traditional modification at 9-site,additional 4-position functionalization provided an exciting blueprint to not only tune electronic structure and excited state via p-n molecular design engineering and space charge-transfer strategy,but also allow for optimizing intermolecular arrangement and obtaining solution-processing ability.The introduction of the 4-site substituent in fluorene based semiconductors may endow materials with unique properties.Finally,we successfully prepared two stable deep-blue light-emitting conjugated polymer,PODOPF and PODOF,by utilizing the 4-substituent fluorene based building block.It is believable that the performance,stability and processibility of reported outstanding fluorene-based conjugated molecules can be further optimized based on this universal building block.
基金supported by Natural Science Foundation of China (61871237, 92067101)Program to Cultivate Middleaged and Young Science Leaders of Universities of Jiangsu Province and Key R&D Plan of Jiangsu Province (BE2021013-3)the Youth Foundation of Nanjing Institute of Industry Technology (YK18 - 02012)。
文摘Mobile edge computing(MEC) networks can provide a variety of services for different applications. End-to-end performance analysis of these services serves as a benchmark for the efficient planning of network resource allocation and routing strategies. In this paper, a performance analysis framework is proposed for the end-to-end data-flows in MEC networks based on stochastic network calculus(SNC). Due to the random nature of routing in MEC networks, probability parameters are introduced in the proposed analysis model to characterize this randomness into the derived expressions. Taking actual communication scenarios into consideration, the end-to-end performance of three network data-flows is analyzed, namely, voice over Internet protocol(VoIP), video, and file transfer protocol(FTP). These network data-flows adopt the preemptive priority scheduling scheme. Based on the arrival processes of these three data-flows, the effect of interference on their performances and the service capacity of each node in the MEC networks, closed-form expressions are derived for showing the relationship between delay, backlog upper bounds, and violation probability of the data-flows. Analytical and simulation results show that delay and backlog performances of the data-flows are influenced by the number of hops in the network and the random probability parameters of interference-flow(IF).
