The immiscible Cu-Fe alloy was characterized by a metastable miscibility gap.With the addition element Zr,the miscibility gap can be extended into the Cu-Fe-Zr ternary system.The effect of the atomic ratio of Cu to Fe...The immiscible Cu-Fe alloy was characterized by a metastable miscibility gap.With the addition element Zr,the miscibility gap can be extended into the Cu-Fe-Zr ternary system.The effect of the atomic ratio of Cu to Fe and Zr content on the behavior of liquid-liquid phase separation was studied.The results show that liquid-liquid phase separation into Cu-rich and Fe-rich liquids took place in the as-quenched Cu-Fe-Zr alloy.A glassy structure with nanoscale phase separation was obtained in the as-quenched(Cu0.5Fe0.5)40Zr60 alloy sample,exhibiting a homogeneous distribution of glassy Cu-rich nanoparticles in glassy Fe-rich matrix.The microstructural evolution and the competitive mechanism of phase formation in the rapidly solidified Cu-Fe-Zr system were discussed in detail.Moreover,the electrical property of the as-quenched Cu-Fe-Zr alloy samples was examined.It displays an abnormal change of electrical resistivity upon temperature in the nanoscale-phase-separation metallic glass.The crystallization behavior of such metallic glass has been discussed.展开更多
Design of rapidly detachable adhesives with high initial bonding strength is of great significance but it is full of great challenge. Here, we report the fast electrically detaching behavior (100% detaching efficiency...Design of rapidly detachable adhesives with high initial bonding strength is of great significance but it is full of great challenge. Here, we report the fast electrically detaching behavior (100% detaching efficiency in just 1 min under dozens of DC voltage) and high initial bonding strength (>12 MPa) of epoxy-based ionic conductive adhesives (ICAs). The epoxy-based ICAs are fabricated by introducing polyethylene glycol dimethyl ether (PEGDE) and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIM]OTF) into epoxy. The combination of PEGDE and [EMIM]OTF enables the free ions to migrate directively in electric field, and the anchoring of PEG chains onto epoxy chains ensures the long-term reliability of ICAs. The investigation on the electrically detaching mechanism suggests that the enrichment and following rapid interfacial electrochemical reactions of [EMIM]OTF lead to formation of metal hydroxide (Me(OH)n) nanoparticles at the bonding interfaces, thus the strong interactions containing interlocked forces, van de Waals’ forces and hydrogen bonding interactions between ICAs and bonding substrates are destroyed. This work provides a promising direction for detachable adhesives with both high initial bonding strength and high detaching efficiency in short time.展开更多
The electrical properties of the structure of GaN grown on an Si （111） substrate with low-temperature （LT） A1N interlayers by metal-organic chemical-vapour deposition are investigated. An abnormal P-type conductio...The electrical properties of the structure of GaN grown on an Si （111） substrate with low-temperature （LT） A1N interlayers by metal-organic chemical-vapour deposition are investigated. An abnormal P-type conduction is observed in our GaN-on-Si structure by Hall effect measurement, which is mainly due to the A1 atom diffusing into the Si substrate and acting as an acceptor dopant. Meanwhile, a constant n-type conduction channel is observed in LT-A1N, which causes a conduction-type conversion at low temperature （50 K） and may further influence the electrical behavior of this structure.展开更多
The micro modeling for electric vehicle and its solution were investigated. A new car-following model for electric vehicle was proposed based on the existing car-following models. The impacts of the electric vehicle&#...The micro modeling for electric vehicle and its solution were investigated. A new car-following model for electric vehicle was proposed based on the existing car-following models. The impacts of the electric vehicle's charging electricity were studied from the numerical perspective. The numerical results show that the electric vehicle's charging electricity will destroy the stability of uniform flow and produce some prominent queues and these traffic phenomena are directly related to the initial headway, the distance between two adjacent charging stations and the number of charging stations. The above results can help traffic engineer to choose the position of charging station and the electric vehicle's driver to adjust his/her driving behavior in the traffic system with charging station.展开更多
A Monte Carlo simulation technique has been used to model the electron transport' behavior, especially the electron density and energy distributions under the influence of a mirror magnetic field and a uniform ele...A Monte Carlo simulation technique has been used to model the electron transport' behavior, especially the electron density and energy distributions under the influence of a mirror magnetic field and a uniform electric field in a positive column of helium direct current(DC) gas discharge Graphs showing the electron density and energy distributions, and the percentage of electrons that reach the wall and the end of the positive column are presented. The results indicate that the mirror magnetic field can control the electron transport behavior in the positive column which are in good agreement with experimental results.展开更多
Electrical impedance measurements were performed on fine-grained concrete with low volume content of conductive steel and carbon fibres, either as a mono or as a hybrid system. The influences were investigated of the...Electrical impedance measurements were performed on fine-grained concrete with low volume content of conductive steel and carbon fibres, either as a mono or as a hybrid system. The influences were investigated of the applied frequencies, of fibre combinations and of the age of the composites on the impedance. The results show that when the applied frequency is increased from 0.98 Hz to 1000 Hz, the impedance of the fibre composites significantly decreases. At the same time, impedance difference between plain concrete and fibre-reinforced concrete is enhanced. Dramatic drop of impedance takes place over the low frequency range, i.e. 0.98 to approximately 31 Hz. Impedance also depends on the volume content of hybrid fibres. The cementitious composite with the highest content of hybrid fibres (1.0% steel fibres and 0.2% carbon fibres by volume) has the lowest impedance at all measuring frequencies. 0.6% fibres by volume seem to be a turning point, from which the variation of impedance slows down with the fibre content increases. On the other hand, the impedance increment of the fibre-reinforced composites slows down with the age after 28 days, comparing to plain concrete. (Author abstract) 8 Refs.展开更多
Understanding the abnormal electricity usage behavior of buildings is essential to enhance the resilience,efficiency,and security of urban/building energy systems while safeguarding occupant comfort.However,data refle...Understanding the abnormal electricity usage behavior of buildings is essential to enhance the resilience,efficiency,and security of urban/building energy systems while safeguarding occupant comfort.However,data reflecting such behavior are often considered as outliers,and removed or smoothed during preprocessing,limiting insights into their potential impacts.This paper proposes an abnormal behavior analysis method that identifies outliers(considering data distribution)and anomalies(considering the physical context)based on the statistical principle and domain knowledge,assessing their effects on energy supply security.A 4-quadrant graph is proposed to quantify and categorize the impacts of buildings on urban energy systems.The method is illustrated by data from 1,451 buildings in a city.Results show that the proposed method can identify abnormal data effectively.Buildings in the primary industry have more outliers,while those in the tertiary industry have more anomalies.Seven buildings affecting both the security and economy of urban energy systems are identified.The outliers rise more frequently from 8:00 to 18:00,on weekdays and in the summer and winter months.However,the anomaly distribution has a weak connection with time.Moreover,the abnormal electricity usage behavior positively correlates with outdoor air temperatures.This method provides a new perspective for identifying potential risks,managing energy usage behavior,and enhancing flexibility of the urban energy systems.展开更多
Objective To observe the effects of repeated subconvulsive electrical stimuli to the hippocampus on the emotional behavior and spatial learning and memory ability in rats.Methods One hundred and eight male Wistar rats...Objective To observe the effects of repeated subconvulsive electrical stimuli to the hippocampus on the emotional behavior and spatial learning and memory ability in rats.Methods One hundred and eight male Wistar rats were randomized into 3 groups. Animals in group SE (n = 42) were given subconvulsive electrical stimulation to the hippocampus through a constant pulsating current of 100 μA with an intratrain frequency of 25 Hz, pulse duration of 1 millisecond, train duration of 10 seconds and interstimulus interval of 7 minutes, 8 times a day, for 5 days. In the electrode control group or CE group (n = 33), animals were implanted with an electrode in the hippocampus, but were not stimulated. Group NC (n =33) animals received no electrode or any stimulation. The emotional behavior of experimental rats was examined by activity in an unfamiliar open field and resistance to capture from the open field, while the spatial learning and memory ability was measured during training in a Morris water maze.Results The stimulated rats tested 1 month after the last round of stimulation displayed substantial decreases in open field activity (scale: 10. 4±2. 3, P<0. 05) and increases in resistance to capture (scale: 2. 85±0. 56, P < 0. 01 ). The amount of time for rats in group SE to find the platform (latency) as a measurement for spatial bias was prolonged (29±7) seconds after 15 trials in the water maze, P<0. 05). The experimental rats swam aimlessly in all four pool quadrants during the probe trial in the Morris water maze.Conclusions Following repeated subconvulsive electrical stimuli to the hippocampus, rats displayed long-lasting significant abnormalities in emotional behavior, increased anxiety and defensiveness, enhanced ease to and delayed habituation to startlement, transitory spatial learning and memory disorder, which parallels many of the symptoms in posttraumatic stress disorder patients.展开更多
As a typical Aurivillius-type compound, CaBi_(4)Ti_(4)O_(15) (CBT) is considered a strong competitor among hightemperature piezoelectric materials, but it is difficult to achieve both high piezoelectric activity and a...As a typical Aurivillius-type compound, CaBi_(4)Ti_(4)O_(15) (CBT) is considered a strong competitor among hightemperature piezoelectric materials, but it is difficult to achieve both high piezoelectric activity and a high Curie temperaturefor CBT. In this work, the method of double-ion co-substituting at different crystalline sites was used to modify the electricalproperties of CBT. The Gd/Mn co-doped CBT ceramics with the chemical formula of Ca_(1−x)Gd_(x)Bi_(4)Ti_(4)O_(15)+0.2 wt% MnO_(2)(CBT–100xGM, x = 0–0.11) were prepared via the conventional sintering process. The phase and valence band structures,chemical compositions and microstructures, dielectric and ferroelectric properties, electrical conduction behaviors, andelectroelastic and piezoelectric properties of the ceramics were characterized. The doping concentration effects of Gd^(3+)were analyzed according to the composition-dependent structures and properties of CBT–100xGM. The donor substitutionof Gd^(3+) for Ca^(2+) at the A-site reduced the tolerance factor of the perovskite-like structure and decreased the concentration ofintrinsic oxygen vacancies. While Mn^(3+) tended to substitute for Ti4+ at the B-site, the extrinsic oxygen vacancies are limitednear the defect center of Ti(Mn) because of the formation of ( ‒MnTi')• as defect dipoles. The thermal depoling behavior ofthe CBT–100xGM ceramics between 300 and 700 ℃ was explained by the thermodynamic characteristics of the defectdipoles. The optimized composition with x = 0.08 (CBT–8GM) had a high TC ≈ 809 ℃ and a high piezoelectric coefficient(d33) ≈ 23 pC/N, as well as a piezoelectric voltage constant (g33) value of up to 21.5×10^(−3)(V·m)/N. Moreover, it can maintaina residual d33 ≈ 80% after being annealed at 700 ℃. This good anti-thermal depoling ability endows this material with greatapplication potential in high-temperature piezoelectric devices with operating temperatures exceeding 500 ℃. Thesynergistic enhancement in the piezoelectric activity and Curie temperature of CBT can be attributed mainly to the donorsubstituting effect of Gd^(3+) at the A-site, as well as the decreased elastic compliance contributed by MnO_(2) as the B-sitedopant.展开更多
Vehicle electrification has emerged as a global strategy to address climate change and emissions externalities from the transportation sector.Deployment of charging infrastructure is needed to accelerate technology ad...Vehicle electrification has emerged as a global strategy to address climate change and emissions externalities from the transportation sector.Deployment of charging infrastructure is needed to accelerate technology adoption;however,managers and policymakers have had limited evidence on the use of public charging stations due to poor data sharing and decentralized ownership across regions.In this article,we use machine learning based classifiers to reveal insights about consumer charging behavior in 72 detected languages including Chinese.We investigate 10 years of consumer reviews in East and Southeast Asia from 2011 to 2021 to enable infrastructure evaluation at a larger geographic scale than previously available.We find evidence that charging stations at government locations result in higher failure rates with consumers compared to charging stations at private points of interest.This evidence contrasts with predictions in the U.S.and European markets,where the performance is closer to parity.We also find that networked stations with communication protocols provide a relatively higher quality of charging services,which favors policy support for connectivity,particularly for underserved or remote areas.展开更多
基金This work was supported by the National Natural Science Foundation of China(Nos.51774264,51574216,51974288 and 51374194)the Natural Science Foundation of Liaoning Province of China(No.2019-MS-332).
文摘The immiscible Cu-Fe alloy was characterized by a metastable miscibility gap.With the addition element Zr,the miscibility gap can be extended into the Cu-Fe-Zr ternary system.The effect of the atomic ratio of Cu to Fe and Zr content on the behavior of liquid-liquid phase separation was studied.The results show that liquid-liquid phase separation into Cu-rich and Fe-rich liquids took place in the as-quenched Cu-Fe-Zr alloy.A glassy structure with nanoscale phase separation was obtained in the as-quenched(Cu0.5Fe0.5)40Zr60 alloy sample,exhibiting a homogeneous distribution of glassy Cu-rich nanoparticles in glassy Fe-rich matrix.The microstructural evolution and the competitive mechanism of phase formation in the rapidly solidified Cu-Fe-Zr system were discussed in detail.Moreover,the electrical property of the as-quenched Cu-Fe-Zr alloy samples was examined.It displays an abnormal change of electrical resistivity upon temperature in the nanoscale-phase-separation metallic glass.The crystallization behavior of such metallic glass has been discussed.
基金supported by the National Natural Science Foundation of China (No. 52103097)the Doctor Foundation of Southwest University of Science and Technology (No. 20zx7144)+3 种基金the Special Foundation for Young Scientists of Sichuan Province (No. 71112541)the Guangdong Natural Science Foundation (No. 2021A1515010675)the Key Project of Guangzhou Science and Technology Plan Project (No. 201904020034)the Guangdong Project of R&D Plan in Key Areas (No. 2020B010180001).
文摘Design of rapidly detachable adhesives with high initial bonding strength is of great significance but it is full of great challenge. Here, we report the fast electrically detaching behavior (100% detaching efficiency in just 1 min under dozens of DC voltage) and high initial bonding strength (>12 MPa) of epoxy-based ionic conductive adhesives (ICAs). The epoxy-based ICAs are fabricated by introducing polyethylene glycol dimethyl ether (PEGDE) and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIM]OTF) into epoxy. The combination of PEGDE and [EMIM]OTF enables the free ions to migrate directively in electric field, and the anchoring of PEG chains onto epoxy chains ensures the long-term reliability of ICAs. The investigation on the electrically detaching mechanism suggests that the enrichment and following rapid interfacial electrochemical reactions of [EMIM]OTF lead to formation of metal hydroxide (Me(OH)n) nanoparticles at the bonding interfaces, thus the strong interactions containing interlocked forces, van de Waals’ forces and hydrogen bonding interactions between ICAs and bonding substrates are destroyed. This work provides a promising direction for detachable adhesives with both high initial bonding strength and high detaching efficiency in short time.
基金supported by the National Basic Research Program of China(Grant No.2010CB923200)the National "863" Project of China(GrantNo.2011AA03A101)+2 种基金the Foundation of the Key Technologies R&D Program of Guangdong Province,China(Grant No.2007A010500011)the International Science and Technology Cooperation Program of China(Grant No.2012DFG52260)the National Science Foundation of China-Guangdong Province Jointed Foundation(Grant No.U0834001)
文摘The electrical properties of the structure of GaN grown on an Si （111） substrate with low-temperature （LT） A1N interlayers by metal-organic chemical-vapour deposition are investigated. An abnormal P-type conduction is observed in our GaN-on-Si structure by Hall effect measurement, which is mainly due to the A1 atom diffusing into the Si substrate and acting as an acceptor dopant. Meanwhile, a constant n-type conduction channel is observed in LT-A1N, which causes a conduction-type conversion at low temperature （50 K） and may further influence the electrical behavior of this structure.
基金Project(71271016)supported the National Natural Science Foundation of China
文摘The micro modeling for electric vehicle and its solution were investigated. A new car-following model for electric vehicle was proposed based on the existing car-following models. The impacts of the electric vehicle's charging electricity were studied from the numerical perspective. The numerical results show that the electric vehicle's charging electricity will destroy the stability of uniform flow and produce some prominent queues and these traffic phenomena are directly related to the initial headway, the distance between two adjacent charging stations and the number of charging stations. The above results can help traffic engineer to choose the position of charging station and the electric vehicle's driver to adjust his/her driving behavior in the traffic system with charging station.
文摘A Monte Carlo simulation technique has been used to model the electron transport' behavior, especially the electron density and energy distributions under the influence of a mirror magnetic field and a uniform electric field in a positive column of helium direct current(DC) gas discharge Graphs showing the electron density and energy distributions, and the percentage of electrons that reach the wall and the end of the positive column are presented. The results indicate that the mirror magnetic field can control the electron transport behavior in the positive column which are in good agreement with experimental results.
文摘Electrical impedance measurements were performed on fine-grained concrete with low volume content of conductive steel and carbon fibres, either as a mono or as a hybrid system. The influences were investigated of the applied frequencies, of fibre combinations and of the age of the composites on the impedance. The results show that when the applied frequency is increased from 0.98 Hz to 1000 Hz, the impedance of the fibre composites significantly decreases. At the same time, impedance difference between plain concrete and fibre-reinforced concrete is enhanced. Dramatic drop of impedance takes place over the low frequency range, i.e. 0.98 to approximately 31 Hz. Impedance also depends on the volume content of hybrid fibres. The cementitious composite with the highest content of hybrid fibres (1.0% steel fibres and 0.2% carbon fibres by volume) has the lowest impedance at all measuring frequencies. 0.6% fibres by volume seem to be a turning point, from which the variation of impedance slows down with the fibre content increases. On the other hand, the impedance increment of the fibre-reinforced composites slows down with the age after 28 days, comparing to plain concrete. (Author abstract) 8 Refs.
基金funded by the program Research and Application of Demand Response Potential Evaluation Technologies Based on Massive Electricity Data(No.B31532238944)supported by the State Grid Hubei Electric Power Research Institute.
文摘Understanding the abnormal electricity usage behavior of buildings is essential to enhance the resilience,efficiency,and security of urban/building energy systems while safeguarding occupant comfort.However,data reflecting such behavior are often considered as outliers,and removed or smoothed during preprocessing,limiting insights into their potential impacts.This paper proposes an abnormal behavior analysis method that identifies outliers(considering data distribution)and anomalies(considering the physical context)based on the statistical principle and domain knowledge,assessing their effects on energy supply security.A 4-quadrant graph is proposed to quantify and categorize the impacts of buildings on urban energy systems.The method is illustrated by data from 1,451 buildings in a city.Results show that the proposed method can identify abnormal data effectively.Buildings in the primary industry have more outliers,while those in the tertiary industry have more anomalies.Seven buildings affecting both the security and economy of urban energy systems are identified.The outliers rise more frequently from 8:00 to 18:00,on weekdays and in the summer and winter months.However,the anomaly distribution has a weak connection with time.Moreover,the abnormal electricity usage behavior positively correlates with outdoor air temperatures.This method provides a new perspective for identifying potential risks,managing energy usage behavior,and enhancing flexibility of the urban energy systems.
基金This study was supported by grants from the National Natural Science Foundation of China (No. 39870284) and the Tenth Five-Year Plan for Medical Projects of PLA (No. 01L028).
文摘Objective To observe the effects of repeated subconvulsive electrical stimuli to the hippocampus on the emotional behavior and spatial learning and memory ability in rats.Methods One hundred and eight male Wistar rats were randomized into 3 groups. Animals in group SE (n = 42) were given subconvulsive electrical stimulation to the hippocampus through a constant pulsating current of 100 μA with an intratrain frequency of 25 Hz, pulse duration of 1 millisecond, train duration of 10 seconds and interstimulus interval of 7 minutes, 8 times a day, for 5 days. In the electrode control group or CE group (n = 33), animals were implanted with an electrode in the hippocampus, but were not stimulated. Group NC (n =33) animals received no electrode or any stimulation. The emotional behavior of experimental rats was examined by activity in an unfamiliar open field and resistance to capture from the open field, while the spatial learning and memory ability was measured during training in a Morris water maze.Results The stimulated rats tested 1 month after the last round of stimulation displayed substantial decreases in open field activity (scale: 10. 4±2. 3, P<0. 05) and increases in resistance to capture (scale: 2. 85±0. 56, P < 0. 01 ). The amount of time for rats in group SE to find the platform (latency) as a measurement for spatial bias was prolonged (29±7) seconds after 15 trials in the water maze, P<0. 05). The experimental rats swam aimlessly in all four pool quadrants during the probe trial in the Morris water maze.Conclusions Following repeated subconvulsive electrical stimuli to the hippocampus, rats displayed long-lasting significant abnormalities in emotional behavior, increased anxiety and defensiveness, enhanced ease to and delayed habituation to startlement, transitory spatial learning and memory disorder, which parallels many of the symptoms in posttraumatic stress disorder patients.
基金funded by the National Natural Science Foundation of China(No.12372179)supported by the State Key Laboratory of Mechanics and Control of Mechanical Structures,Nanjing University of Aeronautics and Astronautics(No.MCMS-E-0522G01).
文摘As a typical Aurivillius-type compound, CaBi_(4)Ti_(4)O_(15) (CBT) is considered a strong competitor among hightemperature piezoelectric materials, but it is difficult to achieve both high piezoelectric activity and a high Curie temperaturefor CBT. In this work, the method of double-ion co-substituting at different crystalline sites was used to modify the electricalproperties of CBT. The Gd/Mn co-doped CBT ceramics with the chemical formula of Ca_(1−x)Gd_(x)Bi_(4)Ti_(4)O_(15)+0.2 wt% MnO_(2)(CBT–100xGM, x = 0–0.11) were prepared via the conventional sintering process. The phase and valence band structures,chemical compositions and microstructures, dielectric and ferroelectric properties, electrical conduction behaviors, andelectroelastic and piezoelectric properties of the ceramics were characterized. The doping concentration effects of Gd^(3+)were analyzed according to the composition-dependent structures and properties of CBT–100xGM. The donor substitutionof Gd^(3+) for Ca^(2+) at the A-site reduced the tolerance factor of the perovskite-like structure and decreased the concentration ofintrinsic oxygen vacancies. While Mn^(3+) tended to substitute for Ti4+ at the B-site, the extrinsic oxygen vacancies are limitednear the defect center of Ti(Mn) because of the formation of ( ‒MnTi')• as defect dipoles. The thermal depoling behavior ofthe CBT–100xGM ceramics between 300 and 700 ℃ was explained by the thermodynamic characteristics of the defectdipoles. The optimized composition with x = 0.08 (CBT–8GM) had a high TC ≈ 809 ℃ and a high piezoelectric coefficient(d33) ≈ 23 pC/N, as well as a piezoelectric voltage constant (g33) value of up to 21.5×10^(−3)(V·m)/N. Moreover, it can maintaina residual d33 ≈ 80% after being annealed at 700 ℃. This good anti-thermal depoling ability endows this material with greatapplication potential in high-temperature piezoelectric devices with operating temperatures exceeding 500 ℃. Thesynergistic enhancement in the piezoelectric activity and Curie temperature of CBT can be attributed mainly to the donorsubstituting effect of Gd^(3+) at the A-site, as well as the decreased elastic compliance contributed by MnO_(2) as the B-sitedopant.
基金supported by funding from the National Science Foundation(Nos.1931980 and 1945332)Microsoft Azure for researchand the U.S.State Department Diplomacy Lab.
文摘Vehicle electrification has emerged as a global strategy to address climate change and emissions externalities from the transportation sector.Deployment of charging infrastructure is needed to accelerate technology adoption;however,managers and policymakers have had limited evidence on the use of public charging stations due to poor data sharing and decentralized ownership across regions.In this article,we use machine learning based classifiers to reveal insights about consumer charging behavior in 72 detected languages including Chinese.We investigate 10 years of consumer reviews in East and Southeast Asia from 2011 to 2021 to enable infrastructure evaluation at a larger geographic scale than previously available.We find evidence that charging stations at government locations result in higher failure rates with consumers compared to charging stations at private points of interest.This evidence contrasts with predictions in the U.S.and European markets,where the performance is closer to parity.We also find that networked stations with communication protocols provide a relatively higher quality of charging services,which favors policy support for connectivity,particularly for underserved or remote areas.
