The introduction of two-dimensional(2D)perovskite layers on top of three-dimensional(3D)perovskite films enhances the performance and stability of perovskite solar cells(PSCs).However,the electronic effect of the spac...The introduction of two-dimensional(2D)perovskite layers on top of three-dimensional(3D)perovskite films enhances the performance and stability of perovskite solar cells(PSCs).However,the electronic effect of the spacer cation and the quality of the 2D capping layer are critical factors in achieving the required results.In this study,we compared two fluorinated salts:4-(trifluoromethyl)benzamidine hydrochloride(4TF-BA·HCl)and 4-fluorobenzamidine hydrochloride(4F-BA·HCl)to engineer the 3D/2D perovskite films.Surprisingly,4F-BA formed a high-performance 3D/2D heterojunction,while4TF-BA produced an amorphous layer on the perovskite films.Our findings indicate that the balanced intramolecular charge polarization,which leads to effective hydrogen bonding,is more favorable in 4F-BA than in 4TF-BA,promoting the formation of a crystalline 2D perovskite.Nevertheless,4TF-BA managed to improve efficiency to 24%,surpassing the control device,primarily due to the natural passivation capabilities of benzamidine.Interestingly,the devices based on 4F-BA demonstrated an efficiency exceeding 25%with greater longevity under various storage conditions compared to 4TF-BA-based and the control devices.展开更多
Perovskite solar cells(PSCs)have emerged as promising photovoltaic technologies owing to their remarkable power conversion efficiency(PCE).However,heat accumulation under continuous illumination remains a critical bot...Perovskite solar cells(PSCs)have emerged as promising photovoltaic technologies owing to their remarkable power conversion efficiency(PCE).However,heat accumulation under continuous illumination remains a critical bottleneck,severely affecting device stability and long-term operational performance.Herein,we present a multifunctional strategy by incorporating highly thermally conductive Ti_(3)C_(2)T_(X) MXene nanosheets into the perovskite layer to simultaneously enhance thermal management and optoelectronic properties.The Ti_(3)C_(2)T_(X) nanosheets,embedded at perovskite grain boundaries,construct efficient thermal conduction pathways,significantly improving the thermal conductivity and diffusivity of the film.This leads to a notable reduction in the device’s steady-state operating temperature from 42.96 to 39.97 under 100 mW cm^(−2) illumination,thereby alleviating heat-induced performance degradation.Beyond thermal regulation,Ti_(3)C_(2)T_(X),with high conductivity and negatively charged surface terminations,also serves as an effective defect passivation agent,reducing trap-assisted recombination,while simultaneously facilitating charge extraction and transport by optimizing interfacial energy alignment.As a result,the Ti_(3)C_(2)T_(X)-modified PSC achieve a champion PCE of 25.13%and exhibit outstanding thermal stability,retaining 80%of the initial PCE after 500 h of thermal aging at 85 and 30±5%relative humidity.(In contrast,control PSC retain only 58%after 200 h.)Moreover,under continuous maximum power point tracking in N2 atmosphere,Ti_(3)C_(2)T_(X)-modified PSC retained 70%of the initial PCE after 500 h,whereas the control PSC drop sharply to 20%.These findings highlight the synergistic role of Ti_(3)C_(2)T_(X) in thermal management and optoelectronic performance,paving the way for the development of high-efficiency and heat-resistant perovskite photovoltaics.展开更多
During electrochemical machining(ECM),the passivation film formed on the surface of titanium alloy can lead to uneven dissolution and pitting.Solid particle erosion can effectively remove this passivation film.In this...During electrochemical machining(ECM),the passivation film formed on the surface of titanium alloy can lead to uneven dissolution and pitting.Solid particle erosion can effectively remove this passivation film.In this paper,the electrochemical dissolution behavior of Ti-6.5Al-2Zr-1Mo-1V(TA15)titanium alloy at without particle impact,low(15°)and high(90°)angle particle impact was investigated,and the influence of Al_(2)O_(3)particles on ECM was systematically expounded.It was found that under the condition of no particle erosion,the surface of electrochemically processed titanium alloy had serious pitting corrosion due to the influence of the passivation film,and the surface roughness(Sa)of the local area reached 10.088μm.Under the condition of a high-impact angle(90°),due to the existence of strain hardening and particle embedding,only the edge of the surface is dissolved,while the central area is almost insoluble,with the surface roughness(S_(a))reaching 16.086μm.On the contrary,under the condition of a low-impact angle(15°),the machining efficiency and surface quality of the material were significantly improved due to the ploughing effect and galvanic corrosion,and the surface roughness(S_(a))reached 2.823μm.Based on these findings,the electrochemical dissolution model of TA15 titanium alloy under different particle erosion conditions was established.展开更多
The passivity and feedback passification problems of fuzzy systems with parameter uncertainties and impulse are first presented in this paper. Based on the parallel distributed compensation （PDC） technique, some pas...The passivity and feedback passification problems of fuzzy systems with parameter uncertainties and impulse are first presented in this paper. Based on the parallel distributed compensation （PDC） technique, some passivity and passification conditions are proposed in terms of linear matrix inequalities （LMIs）. Numerical examples are given to show the correctness and effectiveness of our theoretical results.展开更多
Herein, the effect of high chloride ion(Cl^-) concentration on the corrosion behavior and passive film breakdown of 13Cr martensitic stainless steel under CO_2 environment was demonstrated. The Cl^- concentration was ...Herein, the effect of high chloride ion(Cl^-) concentration on the corrosion behavior and passive film breakdown of 13Cr martensitic stainless steel under CO_2 environment was demonstrated. The Cl^- concentration was varied from 30 to 150 g/L and cyclic potentiodynamic polarization was conducted to investigate the influence of the Cl^- concentration on the corrosion potential(E_(corr)), passive breakdown potential(E_(pit)), and repassivation potential(E_(rep)). The results of the polarization curves revealed that 13Cr stainless steel is susceptible to pitting under high Cl^- concentration. The passive breakdown potential and repassivation potential decreased with the increase of Cl-concentration. The semiconducting behavior of the passive film was investigated by Mott-Schottky analysis and the point defect model(PDM). It was observed that the iron cation vacancies and oxygen vacancies were continuously generated by autocatalytic reactions and the higher Cl^- concentration resulted in higher vacancies in the passive film. Once the excess vacancies condensed at the metal/film interface, the passive film became locally detached from the metal, which led to the breakdown of the passive film.展开更多
Passivity breakdown on 436 ferritic stainless steel(FSS) has been investigated in solutions containing different concentrations of chloride at 25?C and interpreted in terms of the point defect model(PDM). The measured...Passivity breakdown on 436 ferritic stainless steel(FSS) has been investigated in solutions containing different concentrations of chloride at 25?C and interpreted in terms of the point defect model(PDM). The measured near-normal distributions of passivity breakdown potentials for 436 FSS under experimental conditions are in good agreement with the calculated results according to the PDM. The linear dependence of breakdown potential on the square root of potential scanning rate, which was described by the PDM,provides the estimation of the critical concentration of condensed vacancies at the metal/film interface,which leads to the passivity breakdown. This value is in good agreement with that calculated from the microstructure properties of the alloy substrate and the barrier layer of the passive film. This study demonstrates the validity of the PDM in describing the passivity breakdown on 436 FSS in NaCl solutions.展开更多
Impedance control is a well-established technique to control interaction forces in robotics.However,real implementations of impedance control with an inner loop may suffer from several limitations.In particular,the vi...Impedance control is a well-established technique to control interaction forces in robotics.However,real implementations of impedance control with an inner loop may suffer from several limitations.In particular,the viable range of stable stiffness and damping values can be strongly affected by the bandwidth of the inner control loops(e.g.,a torque loop)as well as by the filtering and sampling frequency.This paper provides an extensive analysis on how these aspects influence the stability region of impedance parameters as well as the passivity of the system.This will be supported by both simulations and experimental data.Moreover,a methodology for designing joint impedance controllers based on an inner torque loop and a positive velocity feedback loop will be presented.The goal of the velocity feedback is to increase(given the constraints to preserve stability)the bandwidth of the torque loop without the need of a complex controller.展开更多
By means of matrix decomposition method a criterion is presented for the admissibility of T-S fuzzy descriptor system. Then, the problem of passivity control is studied for a kind of T-S fuzzy descriptor system with u...By means of matrix decomposition method a criterion is presented for the admissibility of T-S fuzzy descriptor system. Then, the problem of passivity control is studied for a kind of T-S fuzzy descriptor system with uncertain parameters, and sufficient conditions which make the closed-loop system admissible and strictly passive are obtained based on linear matrix inequality (LMI). The nonstrict LMIs restricted conditions which characterize the descriptor system are transformed into strict ones, so testing admissibility and passivity of the system can be finished simultaneously. The design scheme of state feedback controller is also obtained. Finally, a numerical example is given to show the validity and feasibility of the proposed approach.展开更多
An adaptive synchronization control method is proposed for chaotic permanent magnet synchronous motors based on the property of a passive system. We prove that the controller makes the synchronization error system bet...An adaptive synchronization control method is proposed for chaotic permanent magnet synchronous motors based on the property of a passive system. We prove that the controller makes the synchronization error system between the driving and the response systems not only passive but also asymptotically stable. The simulation results show that the proposed method is effective and robust against uncertainties in the systemic parameters.展开更多
The problem of passivity analysis is investigated for uncertain stochastic neural networks with discrete interval and distributed time-varying delays.The parameter uncertainties are assumed to be norm bounded and the ...The problem of passivity analysis is investigated for uncertain stochastic neural networks with discrete interval and distributed time-varying delays.The parameter uncertainties are assumed to be norm bounded and the delay is assumed to be time-varying and belongs to a given interval,which means that the lower and upper bounds of interval time-varying delays are available.By constructing proper Lyapunov-Krasovskii functional and employing a combination of the free-weighting matrix method and stochastic analysis technique,new delay-dependent passivity conditions are derived in terms of linear matrix inequalities（LMIs）.Finally,numerical examples are given to show the less conservatism of the proposed conditions.展开更多
Passivity degradation of Alloy 800 in simulated crevice chemistries was systematically investigated using cyclic polarization curve, electrochemical impedance spectroscopy(EIS), Mott-Schottky analysis, Auger electron ...Passivity degradation of Alloy 800 in simulated crevice chemistries was systematically investigated using cyclic polarization curve, electrochemical impedance spectroscopy(EIS), Mott-Schottky analysis, Auger electron spectroscopy(AES)and atomic absorption spectrometry(AAS). Cyclic polarization showed that the pitting potential in a thiosulfate solution was much lower than in either a chloride solution or a sulfate-chloride solution. Mott-Schottky results revealed that passive films showed n-type semiconductivity, and the presence of thiosulfate in chloride solution led to an increased donor density in the passive film. EIS spectra indicated that thiosulfate enhanced the film dissolution rate in chloride solutions. Moreover, thiosulfate enhanced the pitting propagation rate in chloride solution by stabilizing the metastable pits and forming sulfide within the pits.展开更多
This paper reviews sulfur-induced passivity degradation of nuclear materials with emphasis on steam generator(SG)alloys. The state of arts on this topic concerning thermodynamic calculation and experimental data has b...This paper reviews sulfur-induced passivity degradation of nuclear materials with emphasis on steam generator(SG)alloys. The state of arts on this topic concerning thermodynamic calculation and experimental data has been reviewed. Thermodynamic calculation results indicate that the distribution of sulfur species strongly depends on p H and temperature. Experimental data show that solution p H, temperature and solution chemistries can significantly affect the electrochemical behaviors of SG materials and the underlying degradation mechanisms. Some issues when conducting corrosion tests at high temperature should be paid attention to, such as the dissolution of the autoclave, which may affect the facticity of the experimental results.展开更多
Addition of glycerol as a viscosity modifier in concrete is proposed to decrease the permeability of corrosion- inducing ions such as chloride and sulfate. In addition to controlling the permeability of concrete, glyc...Addition of glycerol as a viscosity modifier in concrete is proposed to decrease the permeability of corrosion- inducing ions such as chloride and sulfate. In addition to controlling the permeability of concrete, glycerol could perform as an inhibitor of corrosion of rebar steel. Cyclic polarization studies were carried out on metallographically polished rebar steel specimens in actual concrete solutions at two different pH conditions （pH 12,5 and 9.0） and different chloride concentrations. The threshold concentration of chloride for passivity breakdown at pH 12.5 was greater than 50 × 10-3 mol/L in the absence of glycerol addition. The threshold increased to 81 × 10-3 mol/L upon addition of 2 wt% glycerol. The threshold chloride concentration for passivity breakdown in pH 9.0 cement solution was 0.2 × 10-3 mol/L without glycerol addition. No beneficial effect of glycerol was observed in the low pH condition. However, glycerol enhanced the passivation kinetics of the rebar steel in saturated cement solution, but did not affect the electronic properties of the passive layer. The passive layers exhibited n-type semiconductivity with a charge carrier density in the range of 2-7.5× 10^20 cm-3. Polarization of the specimens to potentials is higher than oxygen evolution potential, resulted in transition top-type semiconducting character due to an accumulation of holes. This phenomenon could be related to the passivity breakdown.展开更多
Feasibility of nonlinear and adaptive control methodologies in multivariable linear timeinvariant systems with state space realization {A, B, C} has apparently been limited by the standard strict passivity （or positi...Feasibility of nonlinear and adaptive control methodologies in multivariable linear timeinvariant systems with state space realization {A, B, C} has apparently been limited by the standard strict passivity （or positive realness） conditions that imply that the product CB must be positive definite symmetric. More recently the symmetry condition has been mitigated, requiring instead that the not necessarily symmetric matrix CB be diagonalizable and with positive real eigenvalues. However, although the mitigated conditions are useful in proving pure stabilizability with Adaptive Controllers, the Model Tracking question has remained open and counterexamples seem to demonstrate total divergence of standard model reference adaptive controllers when the regular passivity conditions are not fully satisfied. Therefore, this paper further extends the previous results, showing that the new passivity conditions do guarantee stability with adaptive model tracking. Examples show how the new conditions solve the case of flexible structures with unknown parameters when perfect collocation is not possible. Also, the so-called counterexamples become simple, well-behaved, examples.展开更多
Mg-Zn-Gd-Nd-Zr alloy （EV31A） is a heat-treatable magnesium （Mg） cast alloy that can be used up to 200 ℃ for automobile and aerospace applications. This alloy has excellent mechanical properties （ultimate tensile...Mg-Zn-Gd-Nd-Zr alloy （EV31A） is a heat-treatable magnesium （Mg） cast alloy that can be used up to 200 ℃ for automobile and aerospace applications. This alloy has excellent mechanical properties （ultimate tensile strength： 280 MPa at room temperature, and -230 MPa at 200 ℃） and improved corrosion resistance. Electrochemical corrosion studies were conducted on this alloy under different heat treatment conditions in 0.1 M NaOH solution with the addition of 0-1000 ppm of chloride. The alloy showed excellent passivity in the 0.1 M NaOH solution. The passive potential range typically extended to more than 1.2 VAg/AgCl. The transpassive potential was observed to be dependent on heat treatment condition of the alloy. More than 80 ppm of chloride was required to induce passivity breakdown in any heat treatment condition. Peak aging at 200 ℃ for 16 h imparted better resistance for localized corrosion than other heat-treated con- ditions. The alloy in the as-received condition showed the highest passivation kinetics due to its smaller grain size that possibly increased the diffusion of reactive elements to form protective oxide. The passive film of the EV31A alloy showed n-type semiconductivity with a charge carrier density of - 2 × 10^21 cm^- 3 with no chloride addition. The charge carrier density increased with chloride addition in the electrolyte which could be correlated with the susceptibility to localized corrosion.展开更多
The natural passive films forrned on Fe_(40)Ni_(40)P_(14)B_6 and Fe_(54.6)Ni_(38)Si_(4.1)B_(2.3)V_1 amorphous alloys long-term exposed in air have been studied by X-ray photoelectron spectroscopy (XPS) and Auger elect...The natural passive films forrned on Fe_(40)Ni_(40)P_(14)B_6 and Fe_(54.6)Ni_(38)Si_(4.1)B_(2.3)V_1 amorphous alloys long-term exposed in air have been studied by X-ray photoelectron spectroscopy (XPS) and Auger electron (including Ar+ ion depth profiling) spectroscopy (AES). The following aspects have been investigated: (1) chemical states of the elements in the films. binding energies and the chemical shifts measured by XPSf (2) structure and composition of the films fand (3) thickness of the passive films determined by AES depth profiling and XPS analysis.展开更多
基金supported by the National Key Research and Development Programs-Intergovernmental International Cooperation in Science and Technology Innovation Project(Grant No.2022YFE0118400)the Natural Science Foundation of Hunan Province(2023JJ50132)+1 种基金Shenzhen Science and Technology Innovation Committee(Grants Nos.JCYJ20220818100211025,and KCXST20221021111616039)Shenzhen Science and Technology Program(No.20231128110928003)。
文摘The introduction of two-dimensional(2D)perovskite layers on top of three-dimensional(3D)perovskite films enhances the performance and stability of perovskite solar cells(PSCs).However,the electronic effect of the spacer cation and the quality of the 2D capping layer are critical factors in achieving the required results.In this study,we compared two fluorinated salts:4-(trifluoromethyl)benzamidine hydrochloride(4TF-BA·HCl)and 4-fluorobenzamidine hydrochloride(4F-BA·HCl)to engineer the 3D/2D perovskite films.Surprisingly,4F-BA formed a high-performance 3D/2D heterojunction,while4TF-BA produced an amorphous layer on the perovskite films.Our findings indicate that the balanced intramolecular charge polarization,which leads to effective hydrogen bonding,is more favorable in 4F-BA than in 4TF-BA,promoting the formation of a crystalline 2D perovskite.Nevertheless,4TF-BA managed to improve efficiency to 24%,surpassing the control device,primarily due to the natural passivation capabilities of benzamidine.Interestingly,the devices based on 4F-BA demonstrated an efficiency exceeding 25%with greater longevity under various storage conditions compared to 4TF-BA-based and the control devices.
基金the National Natural Science Foundation of China(Nos.62374029,22175029,62474033,and W2433038)the Young Elite Scientists Sponsorship Program by CAST(No.YESS20220550)+2 种基金the Sichuan Science and Technology Program(No.2024NSFSC0250)the Natural Science Foundation of Shenzhen Innovation Committee(JCYJ20210324135614040)the Fundamental Research Funds for the Central Universities of China(No.ZYGX2022J032).
文摘Perovskite solar cells(PSCs)have emerged as promising photovoltaic technologies owing to their remarkable power conversion efficiency(PCE).However,heat accumulation under continuous illumination remains a critical bottleneck,severely affecting device stability and long-term operational performance.Herein,we present a multifunctional strategy by incorporating highly thermally conductive Ti_(3)C_(2)T_(X) MXene nanosheets into the perovskite layer to simultaneously enhance thermal management and optoelectronic properties.The Ti_(3)C_(2)T_(X) nanosheets,embedded at perovskite grain boundaries,construct efficient thermal conduction pathways,significantly improving the thermal conductivity and diffusivity of the film.This leads to a notable reduction in the device’s steady-state operating temperature from 42.96 to 39.97 under 100 mW cm^(−2) illumination,thereby alleviating heat-induced performance degradation.Beyond thermal regulation,Ti_(3)C_(2)T_(X),with high conductivity and negatively charged surface terminations,also serves as an effective defect passivation agent,reducing trap-assisted recombination,while simultaneously facilitating charge extraction and transport by optimizing interfacial energy alignment.As a result,the Ti_(3)C_(2)T_(X)-modified PSC achieve a champion PCE of 25.13%and exhibit outstanding thermal stability,retaining 80%of the initial PCE after 500 h of thermal aging at 85 and 30±5%relative humidity.(In contrast,control PSC retain only 58%after 200 h.)Moreover,under continuous maximum power point tracking in N2 atmosphere,Ti_(3)C_(2)T_(X)-modified PSC retained 70%of the initial PCE after 500 h,whereas the control PSC drop sharply to 20%.These findings highlight the synergistic role of Ti_(3)C_(2)T_(X) in thermal management and optoelectronic performance,paving the way for the development of high-efficiency and heat-resistant perovskite photovoltaics.
基金supported by the National Natural Science Foundation of China(No.52175414)the Natural Science Foundation of Jiangsu Province of China(No.BK20220134)+1 种基金the Fundamental Research Funds for the Central Universities,China(No.NE2023002)the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(No.KYCX24_0559)。
文摘During electrochemical machining(ECM),the passivation film formed on the surface of titanium alloy can lead to uneven dissolution and pitting.Solid particle erosion can effectively remove this passivation film.In this paper,the electrochemical dissolution behavior of Ti-6.5Al-2Zr-1Mo-1V(TA15)titanium alloy at without particle impact,low(15°)and high(90°)angle particle impact was investigated,and the influence of Al_(2)O_(3)particles on ECM was systematically expounded.It was found that under the condition of no particle erosion,the surface of electrochemically processed titanium alloy had serious pitting corrosion due to the influence of the passivation film,and the surface roughness(Sa)of the local area reached 10.088μm.Under the condition of a high-impact angle(90°),due to the existence of strain hardening and particle embedding,only the edge of the surface is dissolved,while the central area is almost insoluble,with the surface roughness(S_(a))reaching 16.086μm.On the contrary,under the condition of a low-impact angle(15°),the machining efficiency and surface quality of the material were significantly improved due to the ploughing effect and galvanic corrosion,and the surface roughness(S_(a))reached 2.823μm.Based on these findings,the electrochemical dissolution model of TA15 titanium alloy under different particle erosion conditions was established.
文摘The passivity and feedback passification problems of fuzzy systems with parameter uncertainties and impulse are first presented in this paper. Based on the parallel distributed compensation （PDC） technique, some passivity and passification conditions are proposed in terms of linear matrix inequalities （LMIs）. Numerical examples are given to show the correctness and effectiveness of our theoretical results.
基金financially supported by the National Science and Technology Major Project of China (No. 2016ZX05028-004)
文摘Herein, the effect of high chloride ion(Cl^-) concentration on the corrosion behavior and passive film breakdown of 13Cr martensitic stainless steel under CO_2 environment was demonstrated. The Cl^- concentration was varied from 30 to 150 g/L and cyclic potentiodynamic polarization was conducted to investigate the influence of the Cl^- concentration on the corrosion potential(E_(corr)), passive breakdown potential(E_(pit)), and repassivation potential(E_(rep)). The results of the polarization curves revealed that 13Cr stainless steel is susceptible to pitting under high Cl^- concentration. The passive breakdown potential and repassivation potential decreased with the increase of Cl-concentration. The semiconducting behavior of the passive film was investigated by Mott-Schottky analysis and the point defect model(PDM). It was observed that the iron cation vacancies and oxygen vacancies were continuously generated by autocatalytic reactions and the higher Cl^- concentration resulted in higher vacancies in the passive film. Once the excess vacancies condensed at the metal/film interface, the passive film became locally detached from the metal, which led to the breakdown of the passive film.
基金supported by the National Natural Science Foundation of China (Grants No.51501041 and No.51671059)
文摘Passivity breakdown on 436 ferritic stainless steel(FSS) has been investigated in solutions containing different concentrations of chloride at 25?C and interpreted in terms of the point defect model(PDM). The measured near-normal distributions of passivity breakdown potentials for 436 FSS under experimental conditions are in good agreement with the calculated results according to the PDM. The linear dependence of breakdown potential on the square root of potential scanning rate, which was described by the PDM,provides the estimation of the critical concentration of condensed vacancies at the metal/film interface,which leads to the passivity breakdown. This value is in good agreement with that calculated from the microstructure properties of the alloy substrate and the barrier layer of the passive film. This study demonstrates the validity of the PDM in describing the passivity breakdown on 436 FSS in NaCl solutions.
基金supported by the Istituto Italiano di Tecnologia,and Dr.J.Buchli was supported by a Swiss National Science Foundation professorship.
文摘Impedance control is a well-established technique to control interaction forces in robotics.However,real implementations of impedance control with an inner loop may suffer from several limitations.In particular,the viable range of stable stiffness and damping values can be strongly affected by the bandwidth of the inner control loops(e.g.,a torque loop)as well as by the filtering and sampling frequency.This paper provides an extensive analysis on how these aspects influence the stability region of impedance parameters as well as the passivity of the system.This will be supported by both simulations and experimental data.Moreover,a methodology for designing joint impedance controllers based on an inner torque loop and a positive velocity feedback loop will be presented.The goal of the velocity feedback is to increase(given the constraints to preserve stability)the bandwidth of the torque loop without the need of a complex controller.
基金Supported by National Natural Science Foundation of P. R, China (60574011)the Distinguished Teacher Funds of Liaoning Universities (124210)the Key Laboratory Funds of Liaoning Universities of Intelligent Control Theory and Applications
文摘By means of matrix decomposition method a criterion is presented for the admissibility of T-S fuzzy descriptor system. Then, the problem of passivity control is studied for a kind of T-S fuzzy descriptor system with uncertain parameters, and sufficient conditions which make the closed-loop system admissible and strictly passive are obtained based on linear matrix inequality (LMI). The nonstrict LMIs restricted conditions which characterize the descriptor system are transformed into strict ones, so testing admissibility and passivity of the system can be finished simultaneously. The design scheme of state feedback controller is also obtained. Finally, a numerical example is given to show the validity and feasibility of the proposed approach.
基金Project supported by the Key Program of National Natural Science Foundation of China (Grant No. 50937001)the National Natural Science Foundation of China (Grant Nos. 10862001 and 10947011)the Construction of Key Laboratories in Universities of Guangxi,China (Grant No. 200912)
文摘An adaptive synchronization control method is proposed for chaotic permanent magnet synchronous motors based on the property of a passive system. We prove that the controller makes the synchronization error system between the driving and the response systems not only passive but also asymptotically stable. The simulation results show that the proposed method is effective and robust against uncertainties in the systemic parameters.
基金supported by Department of Science and Technology,New Delhi,India(SR/S4/MS:485/07)
文摘The problem of passivity analysis is investigated for uncertain stochastic neural networks with discrete interval and distributed time-varying delays.The parameter uncertainties are assumed to be norm bounded and the delay is assumed to be time-varying and belongs to a given interval,which means that the lower and upper bounds of interval time-varying delays are available.By constructing proper Lyapunov-Krasovskii functional and employing a combination of the free-weighting matrix method and stochastic analysis technique,new delay-dependent passivity conditions are derived in terms of linear matrix inequalities（LMIs）.Finally,numerical examples are given to show the less conservatism of the proposed conditions.
基金Supported by the Atomic Energy of Canada Limited(AECL)and National Natural Science Foundation of China(No.51371124)
文摘Passivity degradation of Alloy 800 in simulated crevice chemistries was systematically investigated using cyclic polarization curve, electrochemical impedance spectroscopy(EIS), Mott-Schottky analysis, Auger electron spectroscopy(AES)and atomic absorption spectrometry(AAS). Cyclic polarization showed that the pitting potential in a thiosulfate solution was much lower than in either a chloride solution or a sulfate-chloride solution. Mott-Schottky results revealed that passive films showed n-type semiconductivity, and the presence of thiosulfate in chloride solution led to an increased donor density in the passive film. EIS spectra indicated that thiosulfate enhanced the film dissolution rate in chloride solutions. Moreover, thiosulfate enhanced the pitting propagation rate in chloride solution by stabilizing the metastable pits and forming sulfide within the pits.
基金Supported by the National Basic Research Program of China("973"Program,No.2014CB046805)National Natural Science Foundation of China(No.51131007,No.51371124)+1 种基金Natural Science Foundation of Tianjin(No.14JCYBJC17700)the Open-Ended Fund of the Key Laboratory of Nuclear Materials and Safety Assessment(Institute of Metal Research,Chinese Academy of Sciences,China)(No.2016NMSAKF02)
文摘This paper reviews sulfur-induced passivity degradation of nuclear materials with emphasis on steam generator(SG)alloys. The state of arts on this topic concerning thermodynamic calculation and experimental data has been reviewed. Thermodynamic calculation results indicate that the distribution of sulfur species strongly depends on p H and temperature. Experimental data show that solution p H, temperature and solution chemistries can significantly affect the electrochemical behaviors of SG materials and the underlying degradation mechanisms. Some issues when conducting corrosion tests at high temperature should be paid attention to, such as the dissolution of the autoclave, which may affect the facticity of the experimental results.
基金supported by the US Department of Energy under the NEUP PROGRAM,Contract No.DE-NE0000659-003
文摘Addition of glycerol as a viscosity modifier in concrete is proposed to decrease the permeability of corrosion- inducing ions such as chloride and sulfate. In addition to controlling the permeability of concrete, glycerol could perform as an inhibitor of corrosion of rebar steel. Cyclic polarization studies were carried out on metallographically polished rebar steel specimens in actual concrete solutions at two different pH conditions （pH 12,5 and 9.0） and different chloride concentrations. The threshold concentration of chloride for passivity breakdown at pH 12.5 was greater than 50 × 10-3 mol/L in the absence of glycerol addition. The threshold increased to 81 × 10-3 mol/L upon addition of 2 wt% glycerol. The threshold chloride concentration for passivity breakdown in pH 9.0 cement solution was 0.2 × 10-3 mol/L without glycerol addition. No beneficial effect of glycerol was observed in the low pH condition. However, glycerol enhanced the passivation kinetics of the rebar steel in saturated cement solution, but did not affect the electronic properties of the passive layer. The passive layers exhibited n-type semiconductivity with a charge carrier density in the range of 2-7.5× 10^20 cm-3. Polarization of the specimens to potentials is higher than oxygen evolution potential, resulted in transition top-type semiconducting character due to an accumulation of holes. This phenomenon could be related to the passivity breakdown.
文摘Feasibility of nonlinear and adaptive control methodologies in multivariable linear timeinvariant systems with state space realization {A, B, C} has apparently been limited by the standard strict passivity （or positive realness） conditions that imply that the product CB must be positive definite symmetric. More recently the symmetry condition has been mitigated, requiring instead that the not necessarily symmetric matrix CB be diagonalizable and with positive real eigenvalues. However, although the mitigated conditions are useful in proving pure stabilizability with Adaptive Controllers, the Model Tracking question has remained open and counterexamples seem to demonstrate total divergence of standard model reference adaptive controllers when the regular passivity conditions are not fully satisfied. Therefore, this paper further extends the previous results, showing that the new passivity conditions do guarantee stability with adaptive model tracking. Examples show how the new conditions solve the case of flexible structures with unknown parameters when perfect collocation is not possible. Also, the so-called counterexamples become simple, well-behaved, examples.
基金support provided by the US Nuclear Regulatory Commission through a faculty development grant NRC-HQ84-15-G-0025
文摘Mg-Zn-Gd-Nd-Zr alloy （EV31A） is a heat-treatable magnesium （Mg） cast alloy that can be used up to 200 ℃ for automobile and aerospace applications. This alloy has excellent mechanical properties （ultimate tensile strength： 280 MPa at room temperature, and -230 MPa at 200 ℃） and improved corrosion resistance. Electrochemical corrosion studies were conducted on this alloy under different heat treatment conditions in 0.1 M NaOH solution with the addition of 0-1000 ppm of chloride. The alloy showed excellent passivity in the 0.1 M NaOH solution. The passive potential range typically extended to more than 1.2 VAg/AgCl. The transpassive potential was observed to be dependent on heat treatment condition of the alloy. More than 80 ppm of chloride was required to induce passivity breakdown in any heat treatment condition. Peak aging at 200 ℃ for 16 h imparted better resistance for localized corrosion than other heat-treated con- ditions. The alloy in the as-received condition showed the highest passivation kinetics due to its smaller grain size that possibly increased the diffusion of reactive elements to form protective oxide. The passive film of the EV31A alloy showed n-type semiconductivity with a charge carrier density of - 2 × 10^21 cm^- 3 with no chloride addition. The charge carrier density increased with chloride addition in the electrolyte which could be correlated with the susceptibility to localized corrosion.
文摘The natural passive films forrned on Fe_(40)Ni_(40)P_(14)B_6 and Fe_(54.6)Ni_(38)Si_(4.1)B_(2.3)V_1 amorphous alloys long-term exposed in air have been studied by X-ray photoelectron spectroscopy (XPS) and Auger electron (including Ar+ ion depth profiling) spectroscopy (AES). The following aspects have been investigated: (1) chemical states of the elements in the films. binding energies and the chemical shifts measured by XPSf (2) structure and composition of the films fand (3) thickness of the passive films determined by AES depth profiling and XPS analysis.
