The paper has introduced the Journal 'Advanced Technology of Electrical Engineering and Energy',presented its main journal evaluation indexes. The result indicates that the journal has made great progress in r...The paper has introduced the Journal 'Advanced Technology of Electrical Engineering and Energy',presented its main journal evaluation indexes. The result indicates that the journal has made great progress in recent years. It gives much info. about the journal to authors.展开更多
The paper presented the statistics and analysis on papers published on the journal 'Advanced Technology of Electrical Engineering and Energy' from 1996 to 2008: the paper acceptance rate,the paper category,the...The paper presented the statistics and analysis on papers published on the journal 'Advanced Technology of Electrical Engineering and Energy' from 1996 to 2008: the paper acceptance rate,the paper category,the first author's affiliations,the top 7 first authors,the top 10 coauthors and also the journal evaluation indexes of the journal.It offers details of the journal to anyone interested,especially to our editorial board and our broad readers.展开更多
The paper has introduced the journals on electrical engineering in China in detail, presented its publication year, the distributions for all elec. eng. journals and its core journals, the position and level of the jo...The paper has introduced the journals on electrical engineering in China in detail, presented its publication year, the distributions for all elec. eng. journals and its core journals, the position and level of the journals, its main journal evaluation indexes, its core journal proportion and inclusion info. by famous international database. The paper offers much information about the journals on electrical engineering in China to readers, and also points out present problems and gives suggestion.展开更多
Our previous study revealed that early application of electrical field stimulation（EFS） with the anode at the lesion and the cathode distal to the lesion reduced injury potential, inhibited secondary injury and was ...Our previous study revealed that early application of electrical field stimulation（EFS） with the anode at the lesion and the cathode distal to the lesion reduced injury potential, inhibited secondary injury and was neuroprotective in the dorsal corticospinal tract after spinal cord injury（SCI）. The objective of this study was to further evaluate the effect of EFS on protection of anterior horn motoneurons and their target musculature after SCI and its mechanism. Rats were randomized into three equal groups. The EFS group received EFS for 30 minutes immediately after injury at T_（10）. SCI group rats were only subjected to SCI and sham group rats were only subjected to laminectomy. Luxol fast blue staining demonstrated that spinal cord tissue in the injury center was better protected; cross-sectional area and perimeter of injured tissue were significantly smaller in the EFS group than in the SCI group. Immunofluorescence and transmission electron microscopy showed that the number of spinal cord anterior horn motoneurons was greater and the number of abnormal neurons reduced in the EFS group compared with the SCI group. Wet weight and cross-sectional area of vastus lateralis muscles were smaller in the SCI group to in the sham group. However, EFS improved muscle atrophy and behavioral examination showed that EFS significantly increased the angle in the inclined plane test and Tarlov＇s motor grading score. The above results confirm that early EFS can effectively impede spinal cord anterior horn motoneuron loss, promote motor function recovery and reduce muscle atrophy in rats after SCI.展开更多
Aluminum-doped zinc oxide （ZnO：AI） films were deposited by direct current magnetron sputtering in incorporating hydrogen in sputtering gas at room temper- ature. The influences of hydrogen content in sputtering gas...Aluminum-doped zinc oxide （ZnO：AI） films were deposited by direct current magnetron sputtering in incorporating hydrogen in sputtering gas at room temper- ature. The influences of hydrogen content in sputtering gas on the structural, optical, and electrical properties of ZnO：A1 films were systematically investigated. It is found that hydrogen incorporated into ZnO lattice forms shallow donors in ZnO：A1 films and plays an important role in the properties of ZnO：A1 films. The electrical conductivity and infrared （IR） reflectance are improved due to the increase of electron carrier concentration, and the average trans- mittance decreases, which is ascribed to the strong scat- tering from the hydrogen incorporated and oxygen vacancies in ZnO：A1 films. In this study, the resistivity of 5.5 × 10-4 Ω.cm is obtained, the average transmittance of the wavelength in the range of 400-900 nm is almost 86 %, and the IR reflectance reaches 75 % at 2,500 nm, which is higher than that of reported TCO films. The band gap determined by optical absorption is a result of com- petition between Burstein-Moss effect and many-body perturbation effect. However, the hydrogen content in sputtering gas is above 10 %, and the optical band gap shift is independent of hydrogen content in sputtering gas.展开更多
In the current vehicle electric propulsion systems,the thermal design of power modules heavily relies on empirical knowledge,making it challenging to effectively optimize irregularly arranged Pinfin structures,thereby...In the current vehicle electric propulsion systems,the thermal design of power modules heavily relies on empirical knowledge,making it challenging to effectively optimize irregularly arranged Pinfin structures,thereby limiting their performance.This paper aims to review the underlying mechanisms of how irregularly arranged Pinfins influence the thermal characteristics of power modules and introduce collaborative thermal design with DC bus capacitor and motor.Literature considers chip size,placement,coolant flow direction with the goal of reducing thermal resistance of power modules,minimizing chip junction temperature differentials,and optimizing Pinfin layouts.In the first step,algorithms should efficiently generating numerous unique irregular Pinfin layouts to enhance optimization quality.The second step is to efficiently evaluate Pinfin layouts.Simulation accuracy and speed should be ensured to improve computational efficiency.Finally,to improve overall heat dissipation effectiveness,papers establish models for capacitors,motors,to aid collaborative Pinfin optimization.These research outcomes will provide essential support for future developments in high power density motor drive for vehicles.展开更多
Looking at the problem of electrical discharge development in mineral oil, it is easy to see that most studies in this area focused on the setups of bare high voltage electrodes having a point-plane electrode arrangem...Looking at the problem of electrical discharge development in mineral oil, it is easy to see that most studies in this area focused on the setups of bare high voltage electrodes having a point-plane electrode arrangement. The setups with insulated electrodes are the mar- gin of these studies but it seems to be important to find the dependences between the paper insulation on high voltage electrode and parameters of the discharges initiated in the vicinity of this electrode. Hence, in this paper the results of researches intended to reveal the role of insulation wrapping on a HV electrode in the mechanism of electrical discharges in transformer oil under lightning impulse of both polar- ities are presented. This role is determined by analysis of the parameters characterizing the discharges (onset voltage, propagation velocity, time to initiation, rise-time of light impulses) and also by observation of their spatio-temporal development and oscillograms of the light emitted by their channels. The research was performed for two model electrode configurations: an electrode with paper insulation and a bare electrode which had the same outer dimensions as the insulated one. The most essential conclusion from performed experiment is related to times to initiation. These times, equal in the case of insulated electrodes and model bare electrode, indicate that the source of "weak points" of the paper-oil insulation system is the oil, not the surface of insulation wrapping or the metal.展开更多
Photocatalytic decomposition of sugars is a promising way of providing H_(2),CO,and HCOOH as sus-tainable energy vectors.However,the production of C_(1) chemicals requires the cleavage of robust C−C bonds in sugars wi...Photocatalytic decomposition of sugars is a promising way of providing H_(2),CO,and HCOOH as sus-tainable energy vectors.However,the production of C_(1) chemicals requires the cleavage of robust C−C bonds in sugars with concurrent production of H_(2),which remains challenging.Here,the photo-catalytic activity for glucose decomposition to HCOOH,CO(C_(1) chemicals),and H_(2) on Cu/TiO_(2)was enhanced by nitrogen doping.Owing to nitrogen doping,atomically dispersed and stable Cu sites resistant to light irradiation are formed on Cu/TiO_(2).The electronic interaction between Cu and nitrogen ions originates valence band structure and defect levels composed of N 2p orbit,distinct from undoped Cu/TiO_(2).Therefore,the lifetime of charge carriers is prolonged,resulting in the pro-duction of C_(1) chemicals and H_(2) with productivities 1.7 and 2.1 folds that of Cu/TiO_(2).This work pro-vides a strategy to design coordinatively stable Cu ions for photocatalytic biomass conversion.展开更多
Here,p-type polysilicon films are fabricated by ex-situ doping method with ammonium tetraborate tetrahydrate(ATT)as the boron source,named ATT-pPoly.The effects of ATT on the properties of polysilicon films are compre...Here,p-type polysilicon films are fabricated by ex-situ doping method with ammonium tetraborate tetrahydrate(ATT)as the boron source,named ATT-pPoly.The effects of ATT on the properties of polysilicon films are comprehensively analyzed.The Raman spectra reveal that the ATT-pPoly film is composed of grain boundary and crystalline regions.The preferred orientation is the(111)direction.The grain size increases from 16−23 nm to 21−47 nm,by~70%on average.Comparing with other reported films,Hall measurements reveal that the ATT-pPoly film has a higher carrier concentration(>10^(20)cm^(−3))and higher carrier mobility(>30 cm2/(V·s)).The superior properties of the ATT-pPoly film are attributed to the heavy doping and improved grain size.Heavy doping property is proved by the mean sheet resistance(Rsheet,m)and distribution profile.The R_(sheet,m)decreases by more than 30%,and it can be further decreased by 90%if the annealing temperature or duration is increased.The boron concentration of ATT-pPoly film annealed at 950℃ for 45 min is~3×10^(20)cm^(−3),and the distribution is nearly the same,except near the surface.Besides,the standard deviation coefficient(σ)of Rsheet,m is less than 5.0%,which verifies the excellent uniformity of ATT-pPoly film.展开更多
This paper presents some solutions of modem renewable energy system applied actually in dissipation energy source： wind turbine, solar panel battery charge, SSS （support set system）, and standby diesel generator co...This paper presents some solutions of modem renewable energy system applied actually in dissipation energy source： wind turbine, solar panel battery charge, SSS （support set system）, and standby diesel generator cooperated in series, parallel and hybrid system with main energy system. Its solution enable obtain independent individual energy source in different work exploitations. One of problems concerned with alternative energy source is changes of output voltages and output power dependence of climatic conditions. Possible solution is application of decoupled adjustable speed generation system in renewable energy generation. The decoupled generation system consists of： alternative energy source, internal combustion engine drives permanent magnet generator and DC/AC, or AC/AC converter. Performance of single decoupled generation set is discussed supported by results of laboratory tests. To provide high quality voltage is applied an additional energy storage, made from super capacitor and bidirectional DC/DC convert. Such system performs very stiff voltage in any load condition. Integration of solar battery panels or renewable wind energy system is provided via DC link of the variable speed decoupled autonomous generation system. Results of computer simulation and laboratory experiments are presented in the paper.展开更多
Based on the experience of quality objective evaluation procedures of The Institute of Electrical Engineering, the Chinese Academy of Sciences, the methods and processes are summarized in this paper.
Gradient coil is an essential component of a magnetic resonance imaging(MRI)scanner.To achieve high spatial resolution and imaging speed,a high-efficiency gradient coil with high slew rate is required.In consideration...Gradient coil is an essential component of a magnetic resonance imaging(MRI)scanner.To achieve high spatial resolution and imaging speed,a high-efficiency gradient coil with high slew rate is required.In consideration of the safety and comfort of the patient,the mechanical stability,acoustic noise and peripheral nerve stimulation(PNS)are also need to be concerned for practical use.In our previous work,a high-efficiency whole-body gradient coil set with a hybrid cylindrical-planar structure has been presented,which offers significantly improved coil performances.In this work,we propose to design this transverse gradient coil system with transformed magnetic gradient fields.By shifting up the zero point of gradient fields,the designed new Y-gradient coil could provide enhanced electromagnetic performances.With more uniform coil winding arrangement,the net torque of the new coil is significantly reduced and the generated sound pressure level(SPL)is lower at most tested frequency bands.On the other hand,the new transverse gradient coil designed with rotated magnetic gradient fields produces considerably reduced electric field in the human body,which is important for the use of rapid MR sequences.It's demonstrated that a safer and patient-friendly design could be obtained by using transformed magnetic gradient fields,which is critical for practical use.展开更多
Linear flux-switching permanent magnet motors(LFSPMs) have been proposed for long stator applications such as rail transit. However, the conventional linear permanent magnet synchronous motor(LPMSM) suffers from thrus...Linear flux-switching permanent magnet motors(LFSPMs) have been proposed for long stator applications such as rail transit. However, the conventional linear permanent magnet synchronous motor(LPMSM) suffers from thrust ripple, which degrades the motor performance. The thrust ripple in LFSPMs is mainly caused by detent force and asymmetric electromagnetic parameters, excluding external disturbances. Moreover, the 12/13 slot-pole LFSPM exhibits unique inductance characteristics, which lead to different effects on thrust ripple. First, the detent force in the LFSPM is analyzed through finite element method(FEM). In addition, new finite element(FE) models are proposed for further analysis of the cogging force in LFSPMs. Second, the unique inductance characteristics of the 12/13 slot-pole LFSPM are investigated, and then the thrust ripple caused by asymmetric electromagnetic parameters is calculated by the virtual displacement method. Third, the mathematical model considering the thrust ripple is established for the LFSPM, which provides a foundation for subsequent research on thrust ripple suppression control strategies. Finally, the thrust ripple analysis is validated by comparing FEM results, modeling simulations, and experimental data.展开更多
Electron beam fluorescence technology is an advanced non-contact measurement in rarefied flow fields,and the fluorescence signal intensity is positively correlated with the electron beam current.The ion bombardment se...Electron beam fluorescence technology is an advanced non-contact measurement in rarefied flow fields,and the fluorescence signal intensity is positively correlated with the electron beam current.The ion bombardment secondary emission electron gun is suitable for the technology.To enhance the beam current,COMSOL simulations and analyses were conducted to examine plasma density distribution in the discharge chamber under the effects of various conditions and the electric field distribution between the cathode and the spacer gap.The anode shape and discharge pressure conditions were optimized to increase plasma density.Additionally,an improved spacer structure was designed with the dual purpose of enhancing the electric field distribution between the cathode-spacer gaps and improving vacuum differential effects.This design modification aims to increase the pass rate of secondary electrons.Both simulation and experimental results demonstrated that the performance of the optimized electron gun was effectively enhanced.When the electrode voltage remains constant and the discharge gas pressure is adjusted to around 8 Pa,the maximum beam current was increased from 0.9 mA to 1.6 mA.展开更多
N-type Mg_(3)Sb_(2)-based alloys have recently attracted considerable attention due to the high thermoelectric performance.However,the performance degradation occurs because of Mg loss at high temperature.Elemental Mg...N-type Mg_(3)Sb_(2)-based alloys have recently attracted considerable attention due to the high thermoelectric performance.However,the performance degradation occurs because of Mg loss at high temperature.Elemental Mg plays a significantly critical role in thermoelectric performance and thermal stability,where most studies on these compounds have thus far concentrated on the nominal Mg content which heavily depends on the fabrication methods,with few attentions devoted to the essential issue of actual Mg content,resulting in the unclear mechanism of improving their stability,severely limiting their practical applications in thermoelectric power generation.Here,we systematically analyzed the thermoelectric performance,thermal stability,and changed micro structures before and after in situ electronic thermoelectric performance measurement at 750 K,for n-type Mg_(3)Sb_(2)-based alloys with different Mg and Co content.It was found that elemental Mg and Co have a similar effect on adjusting the electron transport characteristic,and the peak values of power factor and ZT are up to 32.4μW cm^(-1)K^(-2)and 1.8,respectively.Thermal stability is more sensitive to the Mg content of material matrix than thermoelectric performance,and the effects of Mgpoor condition on thermal stability cannot be compensated via cationic Co doping.We also proved the route of Mg loss in experiments.By balancing Mg content and Co doping,the optimized sample showed good stability,in which it reduced only by 10%over 170 h of measurement at 750 K.Density functional theory calculation showed that the bonding strength of Co-Mg is stronger than MgMg,also explaining the enhanced thermal stability.展开更多
High-density permanent magnet synchronous motors(PMSMs) are widely used in electric drive systems. However, they are susceptible to temperature influences under complex operating conditions, and prolonged operation at...High-density permanent magnet synchronous motors(PMSMs) are widely used in electric drive systems. However, they are susceptible to temperature influences under complex operating conditions, and prolonged operation at high temperatures can first damage the stator winding insulation, which in turn will damage the windings themselves and cause faults. Therefore, stator temperature monitoring is of crucial importance. This paper summarizes the existing temperature monitoring technologies for stator windings of permanent magnet motors, compares the advantages and disadvantages of various methods to help researchers understand this technology, and analyzes its opportunities and challenges, followed by an outlook.展开更多
After the fabrication of magnetic resonance superconducting magnets,the magnetic field inhomogeneity needs to be accurately measured for subsequent shimming.However,conventional measurement methods are susceptible to ...After the fabrication of magnetic resonance superconducting magnets,the magnetic field inhomogeneity needs to be accurately measured for subsequent shimming.However,conventional measurement methods are susceptible to magnetic fields,have poor compatibility,and are difficult to adapt to various types of magnets.This paper proposes a new field measuring system based on a three-axis movable platform.The system utilizes non-magnetic materials and an innovative hand-wheel lifting design that can be adapted to various aperture magnets,thus obviating the necessity for electrically driven equipment and addressing safety concerns in strong magnetic fields.In addition,the measurement system offers high accuracy up to 1 mm and a wide measurable range.The fields of 3 T and 7 T magnets were mapped using the designed system with diameter of spherical volume(DSV)of 160 mm and 130 mm,respectively.Experimental results demonstrate that the magnetic field measurement system has strong compatibility and can accurately map the magnetic field at arbitrary positions,which is critical for shimming studies.展开更多
Torsional vibration generally causes serious instability and damage problems in many rotating machinery parts.The global dynamic characteristic of nonlinear torsional vibration system with nonlinear rigidity and nonli...Torsional vibration generally causes serious instability and damage problems in many rotating machinery parts.The global dynamic characteristic of nonlinear torsional vibration system with nonlinear rigidity and nonlinear friction force is investigated.On the basis of the generalized dissipation Lagrange's equation,the dynamics equation of nonlinear torsional vibration system is deduced.The bifurcation and chaotic motion in the system subjected to an external harmonic excitation is studied by theoretical analysis and numerical simulation.The stability of unperturbed system is analyzed by using the stability theory of equilibrium positions of Hamiltonian systems.The criterion of existence of chaos phenomena under a periodic perturbation is given by means of Melnikov's method.It is shown that the existence of homoclinic and heteroclinic orbits in the unperturbed system implies chaos arising from breaking of homoclinic or heteroclinic orbits under perturbation.The validity of the result is checked numerically.Periodic doubling bifurcation route to chaos,quasi-periodic route to chaos,intermittency route to chaos are found to occur due to the amplitude varying in some range.The evolution of system dynamic responses is demonstrated in detail by Poincare maps and bifurcation diagrams when the system undergoes a sequence of periodic doubling or quasi-periodic bifurcations to chaos.The conclusion can provide reference for deeply researching the dynamic behavior of mechanical drive systems.展开更多
文摘The paper has introduced the Journal 'Advanced Technology of Electrical Engineering and Energy',presented its main journal evaluation indexes. The result indicates that the journal has made great progress in recent years. It gives much info. about the journal to authors.
文摘The paper presented the statistics and analysis on papers published on the journal 'Advanced Technology of Electrical Engineering and Energy' from 1996 to 2008: the paper acceptance rate,the paper category,the first author's affiliations,the top 7 first authors,the top 10 coauthors and also the journal evaluation indexes of the journal.It offers details of the journal to anyone interested,especially to our editorial board and our broad readers.
文摘The paper has introduced the journals on electrical engineering in China in detail, presented its publication year, the distributions for all elec. eng. journals and its core journals, the position and level of the journals, its main journal evaluation indexes, its core journal proportion and inclusion info. by famous international database. The paper offers much information about the journals on electrical engineering in China to readers, and also points out present problems and gives suggestion.
基金supported by the National Natural Science Foundation of China,No.31400717,51577183the Natural Science Foundation of Beijing of China,No.7164317the Youth Innovation Promotion Association CAS,No.2018172
文摘Our previous study revealed that early application of electrical field stimulation（EFS） with the anode at the lesion and the cathode distal to the lesion reduced injury potential, inhibited secondary injury and was neuroprotective in the dorsal corticospinal tract after spinal cord injury（SCI）. The objective of this study was to further evaluate the effect of EFS on protection of anterior horn motoneurons and their target musculature after SCI and its mechanism. Rats were randomized into three equal groups. The EFS group received EFS for 30 minutes immediately after injury at T_（10）. SCI group rats were only subjected to SCI and sham group rats were only subjected to laminectomy. Luxol fast blue staining demonstrated that spinal cord tissue in the injury center was better protected; cross-sectional area and perimeter of injured tissue were significantly smaller in the EFS group than in the SCI group. Immunofluorescence and transmission electron microscopy showed that the number of spinal cord anterior horn motoneurons was greater and the number of abnormal neurons reduced in the EFS group compared with the SCI group. Wet weight and cross-sectional area of vastus lateralis muscles were smaller in the SCI group to in the sham group. However, EFS improved muscle atrophy and behavioral examination showed that EFS significantly increased the angle in the inclined plane test and Tarlov＇s motor grading score. The above results confirm that early EFS can effectively impede spinal cord anterior horn motoneuron loss, promote motor function recovery and reduce muscle atrophy in rats after SCI.
基金financially supported by the National Natural Science Foundation of China(Nos.21101151 and 51272250)
文摘Aluminum-doped zinc oxide （ZnO：AI） films were deposited by direct current magnetron sputtering in incorporating hydrogen in sputtering gas at room temper- ature. The influences of hydrogen content in sputtering gas on the structural, optical, and electrical properties of ZnO：A1 films were systematically investigated. It is found that hydrogen incorporated into ZnO lattice forms shallow donors in ZnO：A1 films and plays an important role in the properties of ZnO：A1 films. The electrical conductivity and infrared （IR） reflectance are improved due to the increase of electron carrier concentration, and the average trans- mittance decreases, which is ascribed to the strong scat- tering from the hydrogen incorporated and oxygen vacancies in ZnO：A1 films. In this study, the resistivity of 5.5 × 10-4 Ω.cm is obtained, the average transmittance of the wavelength in the range of 400-900 nm is almost 86 %, and the IR reflectance reaches 75 % at 2,500 nm, which is higher than that of reported TCO films. The band gap determined by optical absorption is a result of com- petition between Burstein-Moss effect and many-body perturbation effect. However, the hydrogen content in sputtering gas is above 10 %, and the optical band gap shift is independent of hydrogen content in sputtering gas.
基金supported in part by National Key R&D Program of China (2021YFB2500600)in part by Chinese Academy of Sciences Youth multi-discipline project (JCTD-2021-09)in part by Strategic Piority Research Program of Chinese Academy of Sciences (XDA28040100)
文摘In the current vehicle electric propulsion systems,the thermal design of power modules heavily relies on empirical knowledge,making it challenging to effectively optimize irregularly arranged Pinfin structures,thereby limiting their performance.This paper aims to review the underlying mechanisms of how irregularly arranged Pinfins influence the thermal characteristics of power modules and introduce collaborative thermal design with DC bus capacitor and motor.Literature considers chip size,placement,coolant flow direction with the goal of reducing thermal resistance of power modules,minimizing chip junction temperature differentials,and optimizing Pinfin layouts.In the first step,algorithms should efficiently generating numerous unique irregular Pinfin layouts to enhance optimization quality.The second step is to efficiently evaluate Pinfin layouts.Simulation accuracy and speed should be ensured to improve computational efficiency.Finally,to improve overall heat dissipation effectiveness,papers establish models for capacitors,motors,to aid collaborative Pinfin optimization.These research outcomes will provide essential support for future developments in high power density motor drive for vehicles.
文摘Looking at the problem of electrical discharge development in mineral oil, it is easy to see that most studies in this area focused on the setups of bare high voltage electrodes having a point-plane electrode arrangement. The setups with insulated electrodes are the mar- gin of these studies but it seems to be important to find the dependences between the paper insulation on high voltage electrode and parameters of the discharges initiated in the vicinity of this electrode. Hence, in this paper the results of researches intended to reveal the role of insulation wrapping on a HV electrode in the mechanism of electrical discharges in transformer oil under lightning impulse of both polar- ities are presented. This role is determined by analysis of the parameters characterizing the discharges (onset voltage, propagation velocity, time to initiation, rise-time of light impulses) and also by observation of their spatio-temporal development and oscillograms of the light emitted by their channels. The research was performed for two model electrode configurations: an electrode with paper insulation and a bare electrode which had the same outer dimensions as the insulated one. The most essential conclusion from performed experiment is related to times to initiation. These times, equal in the case of insulated electrodes and model bare electrode, indicate that the source of "weak points" of the paper-oil insulation system is the oil, not the surface of insulation wrapping or the metal.
文摘Photocatalytic decomposition of sugars is a promising way of providing H_(2),CO,and HCOOH as sus-tainable energy vectors.However,the production of C_(1) chemicals requires the cleavage of robust C−C bonds in sugars with concurrent production of H_(2),which remains challenging.Here,the photo-catalytic activity for glucose decomposition to HCOOH,CO(C_(1) chemicals),and H_(2) on Cu/TiO_(2)was enhanced by nitrogen doping.Owing to nitrogen doping,atomically dispersed and stable Cu sites resistant to light irradiation are formed on Cu/TiO_(2).The electronic interaction between Cu and nitrogen ions originates valence band structure and defect levels composed of N 2p orbit,distinct from undoped Cu/TiO_(2).Therefore,the lifetime of charge carriers is prolonged,resulting in the pro-duction of C_(1) chemicals and H_(2) with productivities 1.7 and 2.1 folds that of Cu/TiO_(2).This work pro-vides a strategy to design coordinatively stable Cu ions for photocatalytic biomass conversion.
基金support given by the Natural Science Foundation of Nantong(Grant NO.JC2023065)the Research Program of Nantong Institute of Technology(Grant NO.2023XK(B)07).
文摘Here,p-type polysilicon films are fabricated by ex-situ doping method with ammonium tetraborate tetrahydrate(ATT)as the boron source,named ATT-pPoly.The effects of ATT on the properties of polysilicon films are comprehensively analyzed.The Raman spectra reveal that the ATT-pPoly film is composed of grain boundary and crystalline regions.The preferred orientation is the(111)direction.The grain size increases from 16−23 nm to 21−47 nm,by~70%on average.Comparing with other reported films,Hall measurements reveal that the ATT-pPoly film has a higher carrier concentration(>10^(20)cm^(−3))and higher carrier mobility(>30 cm2/(V·s)).The superior properties of the ATT-pPoly film are attributed to the heavy doping and improved grain size.Heavy doping property is proved by the mean sheet resistance(Rsheet,m)and distribution profile.The R_(sheet,m)decreases by more than 30%,and it can be further decreased by 90%if the annealing temperature or duration is increased.The boron concentration of ATT-pPoly film annealed at 950℃ for 45 min is~3×10^(20)cm^(−3),and the distribution is nearly the same,except near the surface.Besides,the standard deviation coefficient(σ)of Rsheet,m is less than 5.0%,which verifies the excellent uniformity of ATT-pPoly film.
文摘This paper presents some solutions of modem renewable energy system applied actually in dissipation energy source： wind turbine, solar panel battery charge, SSS （support set system）, and standby diesel generator cooperated in series, parallel and hybrid system with main energy system. Its solution enable obtain independent individual energy source in different work exploitations. One of problems concerned with alternative energy source is changes of output voltages and output power dependence of climatic conditions. Possible solution is application of decoupled adjustable speed generation system in renewable energy generation. The decoupled generation system consists of： alternative energy source, internal combustion engine drives permanent magnet generator and DC/AC, or AC/AC converter. Performance of single decoupled generation set is discussed supported by results of laboratory tests. To provide high quality voltage is applied an additional energy storage, made from super capacitor and bidirectional DC/DC convert. Such system performs very stiff voltage in any load condition. Integration of solar battery panels or renewable wind energy system is provided via DC link of the variable speed decoupled autonomous generation system. Results of computer simulation and laboratory experiments are presented in the paper.
文摘Based on the experience of quality objective evaluation procedures of The Institute of Electrical Engineering, the Chinese Academy of Sciences, the methods and processes are summarized in this paper.
基金supported by the Instrument Developing Project of Magnetic Resonance Union of Chinese Academy of Sciences,Grant No.2022GZL002.
文摘Gradient coil is an essential component of a magnetic resonance imaging(MRI)scanner.To achieve high spatial resolution and imaging speed,a high-efficiency gradient coil with high slew rate is required.In consideration of the safety and comfort of the patient,the mechanical stability,acoustic noise and peripheral nerve stimulation(PNS)are also need to be concerned for practical use.In our previous work,a high-efficiency whole-body gradient coil set with a hybrid cylindrical-planar structure has been presented,which offers significantly improved coil performances.In this work,we propose to design this transverse gradient coil system with transformed magnetic gradient fields.By shifting up the zero point of gradient fields,the designed new Y-gradient coil could provide enhanced electromagnetic performances.With more uniform coil winding arrangement,the net torque of the new coil is significantly reduced and the generated sound pressure level(SPL)is lower at most tested frequency bands.On the other hand,the new transverse gradient coil designed with rotated magnetic gradient fields produces considerably reduced electric field in the human body,which is important for the use of rapid MR sequences.It's demonstrated that a safer and patient-friendly design could be obtained by using transformed magnetic gradient fields,which is critical for practical use.
基金partly supported by the CAS Project for Young Scientists in Basic Research under Grant YSBR-045the National Natural Science Foundation of China under Grant 52307071。
文摘Linear flux-switching permanent magnet motors(LFSPMs) have been proposed for long stator applications such as rail transit. However, the conventional linear permanent magnet synchronous motor(LPMSM) suffers from thrust ripple, which degrades the motor performance. The thrust ripple in LFSPMs is mainly caused by detent force and asymmetric electromagnetic parameters, excluding external disturbances. Moreover, the 12/13 slot-pole LFSPM exhibits unique inductance characteristics, which lead to different effects on thrust ripple. First, the detent force in the LFSPM is analyzed through finite element method(FEM). In addition, new finite element(FE) models are proposed for further analysis of the cogging force in LFSPMs. Second, the unique inductance characteristics of the 12/13 slot-pole LFSPM are investigated, and then the thrust ripple caused by asymmetric electromagnetic parameters is calculated by the virtual displacement method. Third, the mathematical model considering the thrust ripple is established for the LFSPM, which provides a foundation for subsequent research on thrust ripple suppression control strategies. Finally, the thrust ripple analysis is validated by comparing FEM results, modeling simulations, and experimental data.
文摘Electron beam fluorescence technology is an advanced non-contact measurement in rarefied flow fields,and the fluorescence signal intensity is positively correlated with the electron beam current.The ion bombardment secondary emission electron gun is suitable for the technology.To enhance the beam current,COMSOL simulations and analyses were conducted to examine plasma density distribution in the discharge chamber under the effects of various conditions and the electric field distribution between the cathode and the spacer gap.The anode shape and discharge pressure conditions were optimized to increase plasma density.Additionally,an improved spacer structure was designed with the dual purpose of enhancing the electric field distribution between the cathode-spacer gaps and improving vacuum differential effects.This design modification aims to increase the pass rate of secondary electrons.Both simulation and experimental results demonstrated that the performance of the optimized electron gun was effectively enhanced.When the electrode voltage remains constant and the discharge gas pressure is adjusted to around 8 Pa,the maximum beam current was increased from 0.9 mA to 1.6 mA.
基金financially supported by Shandong Provincial Natural Science Foundation(No.ZR2023QE028)Dalian National Laboratory for Clean Energy(DNL),CAS,DNL Cooperation Fund,CAS(No.DNL202021)+1 种基金the National Key Research and Development Program of China(No.2024YFB3813800)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.Y202041)
文摘N-type Mg_(3)Sb_(2)-based alloys have recently attracted considerable attention due to the high thermoelectric performance.However,the performance degradation occurs because of Mg loss at high temperature.Elemental Mg plays a significantly critical role in thermoelectric performance and thermal stability,where most studies on these compounds have thus far concentrated on the nominal Mg content which heavily depends on the fabrication methods,with few attentions devoted to the essential issue of actual Mg content,resulting in the unclear mechanism of improving their stability,severely limiting their practical applications in thermoelectric power generation.Here,we systematically analyzed the thermoelectric performance,thermal stability,and changed micro structures before and after in situ electronic thermoelectric performance measurement at 750 K,for n-type Mg_(3)Sb_(2)-based alloys with different Mg and Co content.It was found that elemental Mg and Co have a similar effect on adjusting the electron transport characteristic,and the peak values of power factor and ZT are up to 32.4μW cm^(-1)K^(-2)and 1.8,respectively.Thermal stability is more sensitive to the Mg content of material matrix than thermoelectric performance,and the effects of Mgpoor condition on thermal stability cannot be compensated via cationic Co doping.We also proved the route of Mg loss in experiments.By balancing Mg content and Co doping,the optimized sample showed good stability,in which it reduced only by 10%over 170 h of measurement at 750 K.Density functional theory calculation showed that the bonding strength of Co-Mg is stronger than MgMg,also explaining the enhanced thermal stability.
基金supported by the National Key R&D Program of China (2021YFB2500600)。
文摘High-density permanent magnet synchronous motors(PMSMs) are widely used in electric drive systems. However, they are susceptible to temperature influences under complex operating conditions, and prolonged operation at high temperatures can first damage the stator winding insulation, which in turn will damage the windings themselves and cause faults. Therefore, stator temperature monitoring is of crucial importance. This paper summarizes the existing temperature monitoring technologies for stator windings of permanent magnet motors, compares the advantages and disadvantages of various methods to help researchers understand this technology, and analyzes its opportunities and challenges, followed by an outlook.
基金supported by the National Science Foundation of China(Grant No.52293423 and Grant No.52277031).
文摘After the fabrication of magnetic resonance superconducting magnets,the magnetic field inhomogeneity needs to be accurately measured for subsequent shimming.However,conventional measurement methods are susceptible to magnetic fields,have poor compatibility,and are difficult to adapt to various types of magnets.This paper proposes a new field measuring system based on a three-axis movable platform.The system utilizes non-magnetic materials and an innovative hand-wheel lifting design that can be adapted to various aperture magnets,thus obviating the necessity for electrically driven equipment and addressing safety concerns in strong magnetic fields.In addition,the measurement system offers high accuracy up to 1 mm and a wide measurable range.The fields of 3 T and 7 T magnets were mapped using the designed system with diameter of spherical volume(DSV)of 160 mm and 130 mm,respectively.Experimental results demonstrate that the magnetic field measurement system has strong compatibility and can accurately map the magnetic field at arbitrary positions,which is critical for shimming studies.
基金supported by National Key Technologies R&D Program of the 10th Five-year Plan of China(Grant No.ZZ02-13B-02-03-1)Hebei Provincial Natural Science Foundation of China(Grant No.F2008000882)Hebei Provincial Education Office Scientific Research Projects of China(Grant No.ZH2007102,2007496)
文摘Torsional vibration generally causes serious instability and damage problems in many rotating machinery parts.The global dynamic characteristic of nonlinear torsional vibration system with nonlinear rigidity and nonlinear friction force is investigated.On the basis of the generalized dissipation Lagrange's equation,the dynamics equation of nonlinear torsional vibration system is deduced.The bifurcation and chaotic motion in the system subjected to an external harmonic excitation is studied by theoretical analysis and numerical simulation.The stability of unperturbed system is analyzed by using the stability theory of equilibrium positions of Hamiltonian systems.The criterion of existence of chaos phenomena under a periodic perturbation is given by means of Melnikov's method.It is shown that the existence of homoclinic and heteroclinic orbits in the unperturbed system implies chaos arising from breaking of homoclinic or heteroclinic orbits under perturbation.The validity of the result is checked numerically.Periodic doubling bifurcation route to chaos,quasi-periodic route to chaos,intermittency route to chaos are found to occur due to the amplitude varying in some range.The evolution of system dynamic responses is demonstrated in detail by Poincare maps and bifurcation diagrams when the system undergoes a sequence of periodic doubling or quasi-periodic bifurcations to chaos.The conclusion can provide reference for deeply researching the dynamic behavior of mechanical drive systems.
