FeCoCrNiMox composite powders were prepared using the mechanical alloying technique and made into high-entropy alloy(HEA)coatings with the face-centered cubic phase using plasma spraying to address the element segrega...FeCoCrNiMox composite powders were prepared using the mechanical alloying technique and made into high-entropy alloy(HEA)coatings with the face-centered cubic phase using plasma spraying to address the element segregation problem in HEAs and pre-pare uniform HEA coatings.Scanning electron microscopy,transmission electron microscopy,and X-ray diffractometry were employed to characterize these coatings’microstructure and phase composition.The hardness,elastic modulus,and fracture toughness of coatings were tested,and the corrosion resistance was analyzed in simulated seawater.Results show that the hardness of the coating is HV0.1606.15,the modulus of elasticity is 128.42 GPa,and the fracture toughness is 43.98 MPa·m^(1/2).The corrosion potential of the coating in 3.5wt%NaCl solution is-0.49 V,and the corrosion current density is 1.2×10^(−6)A/cm^(2).The electrochemical system comprises three parts:the electrolyte,the adsorption and metallic oxide films produced during immersion,and the FeCoNiCrMo HEA coating.Over in-creasingly long periods,the corrosion reaction rate increases first and then decreases,the corrosion product film comprising metal oxides reaches a dynamic balance between formation and dissolution,and the internal reaction of the coating declines.展开更多
The neuron model has been widely employed in neural-morphic computing systems and chaotic circuits.This study aims to develop a novel circuit simulation of a three-neuron Hopfield neural network(HNN)with coupled hyper...The neuron model has been widely employed in neural-morphic computing systems and chaotic circuits.This study aims to develop a novel circuit simulation of a three-neuron Hopfield neural network(HNN)with coupled hyperbolic memristors through the modification of a single coupling connection weight.The bistable mode of the hyperbolic memristive HNN(mHNN),characterized by the coexistence of asymmetric chaos and periodic attractors,is effectively demonstrated through the utilization of conventional nonlinear analysis techniques.These techniques include bifurcation diagrams,two-parameter maximum Lyapunov exponent plots,local attractor basins,and phase trajectory diagrams.Moreover,an encryption technique for color images is devised by leveraging the mHNN model and asymmetric structural attractors.This method demonstrates significant benefits in correlation,information entropy,and resistance to differential attacks,providing strong evidence for its effectiveness in encryption.Additionally,an improved modular circuit design method is employed to create the analog equivalent circuit of the memristive HNN.The correctness of the circuit design is confirmed through Multisim simulations,which align with numerical simulations conducted in Matlab.展开更多
Discharge plasma parameter measurement is a key focus in low-temperature plasma research.Traditional diagnostics often require costly equipment,whereas electro-acoustic signals provide a rich,non-invasive,and less com...Discharge plasma parameter measurement is a key focus in low-temperature plasma research.Traditional diagnostics often require costly equipment,whereas electro-acoustic signals provide a rich,non-invasive,and less complex source of discharge information.This study harnesses machine learning to decode these signals.It establishes links between electro-acoustic signals and gas discharge parameters,such as power and distance,thus streamlining the prediction process.By building a spark discharge platform to collect electro-acoustic signals and implementing a series of acoustic signal processing techniques,the Mel-Frequency Cepstral Coefficients(MFCCs)of the acoustic signals are extracted to construct the predictors.Three machine learning models(Linear Regression,k-Nearest Neighbors,and Random Forest)are introduced and applied to the predictors to achieve real-time rapid diagnostic measurement of typical spark discharge power and discharge distance.All models display impressive performance in prediction precision and fitting abilities.Among them,the k-Nearest Neighbors model shows the best performance on discharge power prediction with the lowest mean square error(MSE=0.00571)and the highest R-squared value(R^(2)=0.93877).The experimental results show that the relationship between the electro-acoustic signal and the gas discharge power and distance can be effectively constructed based on the machine learning algorithm,which provides a new idea and basis for the online monitoring and real-time diagnosis of plasma parameters.展开更多
Permanent magnet claw pole machine(PMCPM) is a special kind of transverse flux permanent magnet machine. Compared with other electrical machines, it has the advantages of high torque density and high efficiency for hi...Permanent magnet claw pole machine(PMCPM) is a special kind of transverse flux permanent magnet machine. Compared with other electrical machines, it has the advantages of high torque density and high efficiency for high speed operation. However, because of its complex irregular structure, the manufacturing process using silicon sheets is complicated. Soft magnetic composite material(SMC) is manufactured by powder metallurgy technology, which can produce various shapes of stator core structures, so it is easier to produce various irregular shapes of the stator core. However, the raw SMC material is relatively expensive, and the mechanical strength of SMC is weak. In this paper, a PMCPM with hybrid cores is proposed. With the adoption of hybrid silicon sheet-SMC cores and amorphous alloy-SMC cores, the torque ability of PMCPM can be improved greatly and it can have higher efficiency for more wide operation frequency. Meanwhile, its mechanical strength has been improved and it can be designed for high torque direct drive applications as it is a modular machine. Furthermore, three methods are proposed to reduce the additional eddy current loss which resulted from the employment of hybrid cores in PMCPM.展开更多
To enrich material types applied to additive manufacturing and enlarge application scope of additive manufacturing in conformal cooling tools,M2 high-speed steel specimens were fabricated by selective laser melting(SL...To enrich material types applied to additive manufacturing and enlarge application scope of additive manufacturing in conformal cooling tools,M2 high-speed steel specimens were fabricated by selective laser melting(SLM).Effects of SLM parameters on the microstructure and mechanical properties of M2 high-speed steel were investigated.The results showed that substrate temperature and energy density had significant influence on the densification process of materials and defects control.Models to evaluate the effect of substrate temperature and energy density on hardness were studied.The optimized process parameters,laser power,scan speed,scan distance,and substrate temperature,for fabricated M2 are 220 W,960 mm/s,0.06 mm,and 200℃,respectively.Based on this,the hardness and tensile strength reached 60 HRC and 1000 MPa,respectively.Interlaminar crack formation and suppression mechanism and the relationship between temperature gradient and thermal stress were illustrated.The inhibition effect of substrate temperature on the cracks generated by residual stresses was also explained.AM showed great application potential in the field of special conformal cooling cutting tool preparation.展开更多
Soft magnetic composite(SMC)material is an ideal soft magnetic material employed for developing 3D magnetic flux electromagnetic equipment,due to its advantages of 3D magnetic isotropy characteristic,low eddy current ...Soft magnetic composite(SMC)material is an ideal soft magnetic material employed for developing 3D magnetic flux electromagnetic equipment,due to its advantages of 3D magnetic isotropy characteristic,low eddy current loss,and simple manufacturing process.The permanent magnet claw pole machine(PMCPM)with SMC cores is a good case that the SMC to be adopted for developing 3D flux electrical machines.In this paper,a novel axial-radial flux permanent magnet claw pole machine(ARPMCPM)with SMC cores and ferrite magnets is proposed.Compared with the traditional PMCPM,the proposed ARPMCPM is designed with only one spoke PM rotor and its whole structure is quite compact.For the performance prediction,the 3D finite element method(FEM)is used.Meanwhile,for the performance evaluation,a previously developed axial flux claw pole permanent magnet machine(AFCPM)is employed as the benchmark machine and all these machines are optimized by using the combined multilevel robust Taguchi method.It can be seen that the proposed ARPMCPM is with higher torque/weight density and operation efficiency.展开更多
AgSnO_ 2 electrical contact materials doped with Bi_2O_3,La_2O_3,and TiO_2 were successfully fabricated by the powder metallurgy method under different initial sintering temperatures.The electrical conductivity,densit...AgSnO_ 2 electrical contact materials doped with Bi_2O_3,La_2O_3,and TiO_2 were successfully fabricated by the powder metallurgy method under different initial sintering temperatures.The electrical conductivity,density,hardness,and contact resistance of the Ag Sn O_2/Bi_2O_3,AgSnO_2/La_2O_3,and AgSnO_2/Ti O_2 contact materials were measured and analyzed.The arc-eroded surface morphologies of the doped AgSnO_2 contact materials were investigated by scanning electron microscopy(SEM).The effects of the initial sintering temperature on the physical properties and electrical contact properties of the doped AgSnO_2 contact materials were discussed.The results indicate that the physical properties can be improved and the contact resistance of the AgSnO_2 contact materials can be substantially reduced when the materials are sintered under their optimal initial sintering temperatures.展开更多
Texture regulation is a prominent method to modify the mechanical properties and anisotropy of magnesium alloy.In this work,the Mg-1Al-0.3Ca-0.5Mn-0.2Gd(wt.%)alloy sheet with TD-tilted and circular texture was fabrica...Texture regulation is a prominent method to modify the mechanical properties and anisotropy of magnesium alloy.In this work,the Mg-1Al-0.3Ca-0.5Mn-0.2Gd(wt.%)alloy sheet with TD-tilted and circular texture was fabricated by unidirectional rolling(UR)and multidirectional rolling(MR)method,respectively.Unlike generating a strong in-plane mechanical anisotropy in conventional TD-tilted texture,the novel circular texture sample possessed a weak in-plane yield anisotropy.This can be rationalized by the similar proportion of soft grains with favorable orientation for basalslip and{10.12}tensile twinning during the uniaxial tension of circular-texture sample along different directions.Moreover,compared with the TD-tilted texture,the circular texture improved the elongation to failure both along the rolling direction(RD)and transverse direction(TD).By quasi-in-situ EBSD-assisted slip trace analysis,higher activation of basal slip was observed in the circular-texture sample during RD tension,contributing to its excellent ductility.When loading along the TD,the TD-tilted texture promoted the activation of{10.12}tensile twins significantly,thus providing nucleation sites for cracks and deteriorating the ductility.This research may shed new insights into the development of formable and ductile Mg alloy sheets by texture modification.展开更多
Changes in the concentration of charged ions in neurons can generate induced electric fields,which can further modulate cell membrane potential.In this paper,Fourier coefficients are used to investigate the effect of ...Changes in the concentration of charged ions in neurons can generate induced electric fields,which can further modulate cell membrane potential.In this paper,Fourier coefficients are used to investigate the effect of electric field on vibrational resonance for signal detection in a single neuron model and a bidirectionally coupled neuron model,respectively.The study found that the internal electric field weakens vibrational resonance by changing two factors,membrane potential and phase-locked mode,while the periodic external electric field of an appropriate frequency significantly enhances the vibrational resonance,suggesting that the external electric field may play a constructive role in the detection of weak signals in the brain and neuronal systems.Furthermore,when the coupling of two neurons is considered,the effect of the electric field on the vibrational resonance is similar to that of a single neuron.The paper also illustrates the effect of electric field coupling on vibrational resonance.This study may provide a new theoretical basis for understanding information encoding and transmission in neurons.展开更多
Perovskite solar cells(PSCs)are taking a leading position in thin-film optoelectronic devices due to their excellent optical,physical and electrical properties[1-4].Nevertheless,the stability issue of metal halide per...Perovskite solar cells(PSCs)are taking a leading position in thin-film optoelectronic devices due to their excellent optical,physical and electrical properties[1-4].Nevertheless,the stability issue of metal halide perovskite precursor solution severely retards the future industrialization of PSCs[5-7].In stoichiometry,slight solution composition change will induce severe degradation of device performance.展开更多
As there is no need of permanent magnet(PM)material and only silicon steel sheet required on the rotor,synchronous reluctance machine(SynRM)can be used for many applications and draws a great research interest.For the...As there is no need of permanent magnet(PM)material and only silicon steel sheet required on the rotor,synchronous reluctance machine(SynRM)can be used for many applications and draws a great research interest.For the SynRM,the torque ripple is a big issue and a great of work could been done on reducing it.In this paper,asymmetrical magnetic flux barriers in the SynRM rotor were studied comprehensively,including angle and width of each layer and each side of the magnetic barrier.The SynRMb with asymmetrical and parallel magnetic flux barrier was found as the best way to design SynRM based on the multi-objective design optimization method.Moreover,each parameter was studied to show the design rule of the asymmetrical magnetic flux barrier.As the average torque will be reduced with the asymmetrical barrier is used,the grain-oriented silicon steel is used on stator teeth of the SynRMb(SynRMbG)was proposed and studied.The analysis results show that the proposed new method can make the SynRM have better performance.展开更多
On-site and real-time non-destructive measurement of elastic constants for materials of a component in a in-service structure is a challenge due to structural complexities,such as ambiguous boundary,variable thickness...On-site and real-time non-destructive measurement of elastic constants for materials of a component in a in-service structure is a challenge due to structural complexities,such as ambiguous boundary,variable thickness,nonuniform material properties.This work develops for the first time a method that uses ultrasound echo groups and artificial neural network(ANN)for reliable on-site real-time identification of material parameters.The use of echo groups allows the use of lower frequencies,and hence more accommodative to structural complexity.To train the ANNs,a numerical model is established that is capable of computing the waveform of ultrasonic echo groups for any given set of material properties of a given structure.The waveform of an ultrasonic echo groups at an interest location on the surface the structure with material parameters varying in a predefined range are then computed using the numerical model.This results in a set of dataset for training the ANN model.Once the ANN is trained,the material parameters can be identified simultaneously using the actual measured echo waveform as input to the ANN.Intensive tests have been conducted both numerically and experimentally to evaluate the effectiveness and accuracy of the currently proposed method.The results show that the maximum identification error of numerical example is less than 2%,and the maximum identification error of experimental test is less than 7%.Compared with currently prevailing methods and equipment,the proposefy the density and thickness,in addition to the elastic constants.Moreover,the reliability and accuracy of inverse prediction is significantly improved.Thus,it has broad applications and enables real-time field measurements,which has not been fulfilled by any other available methods or equipment.展开更多
The Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)composite coatings were prepared by plasma spraying Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)and Al−Cr2O3−SiC composite powders,respectively.The microstructure,formation mechanism and proper...The Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)composite coatings were prepared by plasma spraying Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)and Al−Cr2O3−SiC composite powders,respectively.The microstructure,formation mechanism and properties of the two Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)composite coatings obtained by plasma spraying were investigated,and the reaction mechanism of the Al−Cr_(2)O_(3)−SiC system was explored.The results show that the coating obtained by plasma spraying Al−Cr_(2)O_(3)−SiC composite powders had thinner lamella and more tortuous interlayer interface,and the in-situ synthesized Cr_(7)C_(3),CrSi_(2) and Al_(2)O_(3) in the coating were all nano-crystallines.Compared with the Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)coating prepared by plasma spraying Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)composite powders,the plasma-sprayed Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)coating obtained from Al−Cr_(2)O_(3)−SiC composite powders had higher density,higher microhardness(increased by 20%),better fracture toughness and lower wear rate(reduced by 28%).展开更多
With great achievements in efficiency,stability,and large-scale preparation of perovskite solar cells(PSCs),the com-mercialization of PSC is ongoing,but there is still an issue on lead toxicity.Although lead content i...With great achievements in efficiency,stability,and large-scale preparation of perovskite solar cells(PSCs),the com-mercialization of PSC is ongoing,but there is still an issue on lead toxicity.Although lead content in the device is low,the water solubility of lead salts leads to potential environmental pollution.At present,the non-lead perovskites studied in-clude:divalent metal perovskite(e.g.,Sn^(2+),Ge^(2+),Cu^(2+)),trivalent metal perovskite(e.g.,Bi^(3+),Sb^(3+),In^(3+)),tetravalent met-al double perovskite(e.g.,Sn^(4+),Pd^(4+),Ti^(4+),Pt^(4+))and mono-trivalent mixed double perovskite(e.g.,Ag+and Bi^(3+),Ag+and In^(3+),Ag^(+)and Sb^(3+)).Their properties are summarized in Table 1.Since the first report on non-lead double perovskite Cs2AgBiBr6 in 2016^([1]).展开更多
During the operation of high-voltage cables,external stress and residual stress can affect the aggregated structure of insulating materials and lead to significant deterioration in their electrical performance.To inve...During the operation of high-voltage cables,external stress and residual stress can affect the aggregated structure of insulating materials and lead to significant deterioration in their electrical performance.To investigate the evolution characteristics of the electrical properties of cross-linked polyethylene(XLPE)under mechanical stress,this paper ex-plains the relationship between the aggregated structure of XLPE and its electrical properties and proposes a method for improving insulation performance under me-chanical stress.The results show that metallocene polyethylene used as a nucleating agent can promote crystallisation through heterogeneous nucleation and increase Young's modulus by non-uniform nucleation,increasing crystallinity and reducing interplanar spacing,resulting in more complete crystal forms and reduced damage to the aggregated structure during the tensile process.After nucleating agent modification,the XLPE crystallisation becomes more uniform,and interfacial adhesion forces increase.The weakened interface damage process between the amorphous and crystalline regions under tensile stress effectively inhibits the process of molecular chain polarisation turning and reduces trap density.The modified XLPE crystal structure shows a tendency towards densification and enhanced molecular chain interactions,which can reduce the damage to the aggregated structure under tensile stress,while the reduced free volume inside the material and the shortened average free path of carriers can weaken the damage of high-energy electrons to molecular chains,thereby inhibiting the process of electrical tree degradation.The results show that nucleating agents have great potential for maintaining the stable operation of XLPE cables under mechanical stress.展开更多
This paper presents a method to study the vector magnetic properties of magnetic materials under alternating and rotational magnetic field using 2-D vector hybrid hysteresis model.Combining Preisach model and Stoner-W...This paper presents a method to study the vector magnetic properties of magnetic materials under alternating and rotational magnetic field using 2-D vector hybrid hysteresis model.Combining Preisach model and Stoner-Wohlfarth(S-W)model,the vector hybrid hysteresis model is established for magnetic materials.The alternating and rotational hysteresis properties are calculated under different excitation frequency,respectively.And the computed results are compared with the experimental measurement ones.It is shown that the vector model can simulate the alternating and rotational magnetic properties effectively under low magnetization fields and low excitation frequency.展开更多
The performance of traditional flux switching permanent magnet tubular machine(FSPMTM)are improved by using new material and structure in this paper.The existing silicon steel sheet making for all mover cores or part ...The performance of traditional flux switching permanent magnet tubular machine(FSPMTM)are improved by using new material and structure in this paper.The existing silicon steel sheet making for all mover cores or part of stator cores are replaced by soft magnetic composite(SMC)cores,and the lamination direction of the silicon steel sheet in stator cores have be changed.The eddy current loss of the machine with hybrid cores will be reduced greatly as the magnetic flux will not pass through the silicon steel sheet vertically.In order to reduce the influence of end effect,the unequal stator width design method is proposed.With the new design,the symmetry of the permanent magnet flux linkage has been improved greatly and the cogging force caused by the end effect has been reduced.Both 2-D and 3-D finite element methods(FEM)are applied for the quantitative analysis.展开更多
This paper proposes a new rotary flux switching transverse flux machine with the ability of linear motion(FSTFMaLM),in which both the stator and the rotor cores are made by using soft magnetic composite(SMC)materials....This paper proposes a new rotary flux switching transverse flux machine with the ability of linear motion(FSTFMaLM),in which both the stator and the rotor cores are made by using soft magnetic composite(SMC)materials.With the special design pattern,for the rotary motion model,the proposed machine can combine both the advantages of the flux switching permanent magnet machine(FSPMM)and the transverse flux machine(TFM).It can output with relatively high torque density,and as there is no windings or the magnets on the rotor cores,the proposed machine can operate in the high speed region to improve the output power.With the adoption of the SMC materials,the manufacturing of this machine can be quite easy.By stacking the rotor core together and prolong it with the determined length in the axial direction,in addition with the special control algorithm,the proposed machine can have the ability of the linear motion.In this paper,the operation principle of this machine has been explained and the design methods are also presented.To seek the better performance,the main dimension of the machine is optimized,and for the performance evaluation,the finite element method(FEM)is adopted.The proposed machine can be used for the electric driving systems,robotic systems or other applications where the linear motion ability is required.展开更多
A semi-empirical equation of state model for aluminum in a warm dense matter regime is constructed. The equation of state, which is subdivided into a cold term, thermal contributions of ions and electrons, covers a br...A semi-empirical equation of state model for aluminum in a warm dense matter regime is constructed. The equation of state, which is subdivided into a cold term, thermal contributions of ions and electrons, covers a broad range of phase diagram from solid state to plasma state. The cold term and thermal contribution of ions are from the Bushman–Lomonosov model, in which several undetermined parameters are fitted based on equation of state theories and specific experimental data. The Thomas–Fermi–Kirzhnits model is employed to estimate the thermal contribution of electrons. Some practical modifications are introduced to the Thomas–Fermi–Kirzhnits model to improve the prediction of the equation of state model. Theoretical calculation of thermodynamic parameters, including phase diagram, curves of isothermal compression at ambient temperature, melting, and Hugoniot, are analyzed and compared with relevant experimental data and other theoretical evaluations.展开更多
Transient receptor potential vanilloid subtype 1 (TRPV1) is a polymodel sensory receptor and can be activated by moderate temperature (≥ 43 ℃). Though extensive researches on the heat-activation mechanism revealed s...Transient receptor potential vanilloid subtype 1 (TRPV1) is a polymodel sensory receptor and can be activated by moderate temperature (≥ 43 ℃). Though extensive researches on the heat-activation mechanism revealed some key elements that participate in the heat-sensation pathway, the detailed thermal-gating mechanism of TRPV1 is still unclear. We investigate the heat-activation process of TRPV1 channel using the molecular dynamics simulation method at different temperatures. It is found that the favored state of the supposed upper gate of TRPV1 cannot form constriction to ion permeation. Oscillation of S5 helix originated from thermal fluctuation and forming/breaking of two key hydrogen bonds can transmit to S6 helix through the hydrophobic contact between S5 and S6 helix. We propose that this is the pathway from heat sensor of TRPV1 to the opening of the lower gate. The heat-activation mechanism of TRPV1 presented in this work can help further functional study of TRPV1 channel.展开更多
基金supported by the National Natural Natural Science Foundation of China(No.52271055)the Natural Science Foundation of Hebei Province,China(No.E2024202154).
文摘FeCoCrNiMox composite powders were prepared using the mechanical alloying technique and made into high-entropy alloy(HEA)coatings with the face-centered cubic phase using plasma spraying to address the element segregation problem in HEAs and pre-pare uniform HEA coatings.Scanning electron microscopy,transmission electron microscopy,and X-ray diffractometry were employed to characterize these coatings’microstructure and phase composition.The hardness,elastic modulus,and fracture toughness of coatings were tested,and the corrosion resistance was analyzed in simulated seawater.Results show that the hardness of the coating is HV0.1606.15,the modulus of elasticity is 128.42 GPa,and the fracture toughness is 43.98 MPa·m^(1/2).The corrosion potential of the coating in 3.5wt%NaCl solution is-0.49 V,and the corrosion current density is 1.2×10^(−6)A/cm^(2).The electrochemical system comprises three parts:the electrolyte,the adsorption and metallic oxide films produced during immersion,and the FeCoNiCrMo HEA coating.Over in-creasingly long periods,the corrosion reaction rate increases first and then decreases,the corrosion product film comprising metal oxides reaches a dynamic balance between formation and dissolution,and the internal reaction of the coating declines.
基金Project supported by the National Nature Science Foundation of China(Grant Nos.51737003 and 51977060)the Natural Science Foundation of Hebei Province(Grant No.E2011202051).
文摘The neuron model has been widely employed in neural-morphic computing systems and chaotic circuits.This study aims to develop a novel circuit simulation of a three-neuron Hopfield neural network(HNN)with coupled hyperbolic memristors through the modification of a single coupling connection weight.The bistable mode of the hyperbolic memristive HNN(mHNN),characterized by the coexistence of asymmetric chaos and periodic attractors,is effectively demonstrated through the utilization of conventional nonlinear analysis techniques.These techniques include bifurcation diagrams,two-parameter maximum Lyapunov exponent plots,local attractor basins,and phase trajectory diagrams.Moreover,an encryption technique for color images is devised by leveraging the mHNN model and asymmetric structural attractors.This method demonstrates significant benefits in correlation,information entropy,and resistance to differential attacks,providing strong evidence for its effectiveness in encryption.Additionally,an improved modular circuit design method is employed to create the analog equivalent circuit of the memristive HNN.The correctness of the circuit design is confirmed through Multisim simulations,which align with numerical simulations conducted in Matlab.
基金partially supported by National Natural Science Foundation of China(No.52377155)the State Key Laboratory of Reliability and Intelligence of Electrical Equipment(No.EERI-KF2021001)Hebei University of Technology。
文摘Discharge plasma parameter measurement is a key focus in low-temperature plasma research.Traditional diagnostics often require costly equipment,whereas electro-acoustic signals provide a rich,non-invasive,and less complex source of discharge information.This study harnesses machine learning to decode these signals.It establishes links between electro-acoustic signals and gas discharge parameters,such as power and distance,thus streamlining the prediction process.By building a spark discharge platform to collect electro-acoustic signals and implementing a series of acoustic signal processing techniques,the Mel-Frequency Cepstral Coefficients(MFCCs)of the acoustic signals are extracted to construct the predictors.Three machine learning models(Linear Regression,k-Nearest Neighbors,and Random Forest)are introduced and applied to the predictors to achieve real-time rapid diagnostic measurement of typical spark discharge power and discharge distance.All models display impressive performance in prediction precision and fitting abilities.Among them,the k-Nearest Neighbors model shows the best performance on discharge power prediction with the lowest mean square error(MSE=0.00571)and the highest R-squared value(R^(2)=0.93877).The experimental results show that the relationship between the electro-acoustic signal and the gas discharge power and distance can be effectively constructed based on the machine learning algorithm,which provides a new idea and basis for the online monitoring and real-time diagnosis of plasma parameters.
基金supported by the National Natural Science Foundation of China under project 52007047the Outstanding Youth Innovation Project funded by State Key Laboratory of Reliability and Intelligence of Electrical Equipment EERI_OY2021005。
文摘Permanent magnet claw pole machine(PMCPM) is a special kind of transverse flux permanent magnet machine. Compared with other electrical machines, it has the advantages of high torque density and high efficiency for high speed operation. However, because of its complex irregular structure, the manufacturing process using silicon sheets is complicated. Soft magnetic composite material(SMC) is manufactured by powder metallurgy technology, which can produce various shapes of stator core structures, so it is easier to produce various irregular shapes of the stator core. However, the raw SMC material is relatively expensive, and the mechanical strength of SMC is weak. In this paper, a PMCPM with hybrid cores is proposed. With the adoption of hybrid silicon sheet-SMC cores and amorphous alloy-SMC cores, the torque ability of PMCPM can be improved greatly and it can have higher efficiency for more wide operation frequency. Meanwhile, its mechanical strength has been improved and it can be designed for high torque direct drive applications as it is a modular machine. Furthermore, three methods are proposed to reduce the additional eddy current loss which resulted from the employment of hybrid cores in PMCPM.
基金Supported by National Natural Science Foundation of China (Grant No.52005154)Hebei Provincial Natural Science Foundation (Grant No.E2020202035)。
文摘To enrich material types applied to additive manufacturing and enlarge application scope of additive manufacturing in conformal cooling tools,M2 high-speed steel specimens were fabricated by selective laser melting(SLM).Effects of SLM parameters on the microstructure and mechanical properties of M2 high-speed steel were investigated.The results showed that substrate temperature and energy density had significant influence on the densification process of materials and defects control.Models to evaluate the effect of substrate temperature and energy density on hardness were studied.The optimized process parameters,laser power,scan speed,scan distance,and substrate temperature,for fabricated M2 are 220 W,960 mm/s,0.06 mm,and 200℃,respectively.Based on this,the hardness and tensile strength reached 60 HRC and 1000 MPa,respectively.Interlaminar crack formation and suppression mechanism and the relationship between temperature gradient and thermal stress were illustrated.The inhibition effect of substrate temperature on the cracks generated by residual stresses was also explained.AM showed great application potential in the field of special conformal cooling cutting tool preparation.
基金supported by the National Natural Science Foundation of China under project 52007047in part by the Outstanding Youth Innovation Project funded by State Key Laboratory of Reliability and Intelligence of Electrical Equipment EERI_OY2021005,and EERI_KF2021014。
文摘Soft magnetic composite(SMC)material is an ideal soft magnetic material employed for developing 3D magnetic flux electromagnetic equipment,due to its advantages of 3D magnetic isotropy characteristic,low eddy current loss,and simple manufacturing process.The permanent magnet claw pole machine(PMCPM)with SMC cores is a good case that the SMC to be adopted for developing 3D flux electrical machines.In this paper,a novel axial-radial flux permanent magnet claw pole machine(ARPMCPM)with SMC cores and ferrite magnets is proposed.Compared with the traditional PMCPM,the proposed ARPMCPM is designed with only one spoke PM rotor and its whole structure is quite compact.For the performance prediction,the 3D finite element method(FEM)is used.Meanwhile,for the performance evaluation,a previously developed axial flux claw pole permanent magnet machine(AFCPM)is employed as the benchmark machine and all these machines are optimized by using the combined multilevel robust Taguchi method.It can be seen that the proposed ARPMCPM is with higher torque/weight density and operation efficiency.
基金financially supported by the National Natural Science Foundation of China (No.51777057)the Natural Science Foundation of Hebei Province, China (No.E2016202106)the Science and Technology Research Project of Colleges and Universities in Hebei Province, China (No.ZD2016078)
文摘AgSnO_ 2 electrical contact materials doped with Bi_2O_3,La_2O_3,and TiO_2 were successfully fabricated by the powder metallurgy method under different initial sintering temperatures.The electrical conductivity,density,hardness,and contact resistance of the Ag Sn O_2/Bi_2O_3,AgSnO_2/La_2O_3,and AgSnO_2/Ti O_2 contact materials were measured and analyzed.The arc-eroded surface morphologies of the doped AgSnO_2 contact materials were investigated by scanning electron microscopy(SEM).The effects of the initial sintering temperature on the physical properties and electrical contact properties of the doped AgSnO_2 contact materials were discussed.The results indicate that the physical properties can be improved and the contact resistance of the AgSnO_2 contact materials can be substantially reduced when the materials are sintered under their optimal initial sintering temperatures.
基金supports from The National Natural Science Foundation of China(nos.52222409,52074132,and U19A2084)The National Key Research and Development Program(no.2022YFE0122000)are greatly acknowledgedsupport from The Science and Technology Development Program of Jilin Province(no.20210301025GX).
文摘Texture regulation is a prominent method to modify the mechanical properties and anisotropy of magnesium alloy.In this work,the Mg-1Al-0.3Ca-0.5Mn-0.2Gd(wt.%)alloy sheet with TD-tilted and circular texture was fabricated by unidirectional rolling(UR)and multidirectional rolling(MR)method,respectively.Unlike generating a strong in-plane mechanical anisotropy in conventional TD-tilted texture,the novel circular texture sample possessed a weak in-plane yield anisotropy.This can be rationalized by the similar proportion of soft grains with favorable orientation for basalslip and{10.12}tensile twinning during the uniaxial tension of circular-texture sample along different directions.Moreover,compared with the TD-tilted texture,the circular texture improved the elongation to failure both along the rolling direction(RD)and transverse direction(TD).By quasi-in-situ EBSD-assisted slip trace analysis,higher activation of basal slip was observed in the circular-texture sample during RD tension,contributing to its excellent ductility.When loading along the TD,the TD-tilted texture promoted the activation of{10.12}tensile twins significantly,thus providing nucleation sites for cracks and deteriorating the ductility.This research may shed new insights into the development of formable and ductile Mg alloy sheets by texture modification.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51737003 and 51977060)the Natural Science Foundation of Hebei Province,China(Grant No.E2011202051)。
文摘Changes in the concentration of charged ions in neurons can generate induced electric fields,which can further modulate cell membrane potential.In this paper,Fourier coefficients are used to investigate the effect of electric field on vibrational resonance for signal detection in a single neuron model and a bidirectionally coupled neuron model,respectively.The study found that the internal electric field weakens vibrational resonance by changing two factors,membrane potential and phase-locked mode,while the periodic external electric field of an appropriate frequency significantly enhances the vibrational resonance,suggesting that the external electric field may play a constructive role in the detection of weak signals in the brain and neuronal systems.Furthermore,when the coupling of two neurons is considered,the effect of the electric field on the vibrational resonance is similar to that of a single neuron.The paper also illustrates the effect of electric field coupling on vibrational resonance.This study may provide a new theoretical basis for understanding information encoding and transmission in neurons.
基金supported by the National Natural Science Foundation of China(62004058,U21A2076,21701041,52071048)the National Natural Science Foundation of China(21961160720)+6 种基金Natural Science Foundation of Hebei Province(F2020202022)the Open Fund of the State Key Laboratory of Integrated Optoelectronics(IOSKL2020KF09)State Key Laboratory of Reliability and Intelligence of Electrical Equipment(EERI_PI20200005)the Support Plan for Overseas Students to Return to China for Entrepreneurship and Innovation(cx2020003)the Fundamental Research Funds for the Central Universities(2020CDJ-LHZZ-074)Natural Science Foundation of Chongqing(cstc2020jcyj-msxm X0629)the open research fund of Songshan Lake Materials Laboratory(2021SLABFK02)。
文摘Perovskite solar cells(PSCs)are taking a leading position in thin-film optoelectronic devices due to their excellent optical,physical and electrical properties[1-4].Nevertheless,the stability issue of metal halide perovskite precursor solution severely retards the future industrialization of PSCs[5-7].In stoichiometry,slight solution composition change will induce severe degradation of device performance.
基金the National Natural Science Foundation of China under Project 52007047,in part by the National Natural Science Foundation of China under Project 51877065,and in part by Natural Science Foundation of Hebei Province under Project E2019202220.
文摘As there is no need of permanent magnet(PM)material and only silicon steel sheet required on the rotor,synchronous reluctance machine(SynRM)can be used for many applications and draws a great research interest.For the SynRM,the torque ripple is a big issue and a great of work could been done on reducing it.In this paper,asymmetrical magnetic flux barriers in the SynRM rotor were studied comprehensively,including angle and width of each layer and each side of the magnetic barrier.The SynRMb with asymmetrical and parallel magnetic flux barrier was found as the best way to design SynRM based on the multi-objective design optimization method.Moreover,each parameter was studied to show the design rule of the asymmetrical magnetic flux barrier.As the average torque will be reduced with the asymmetrical barrier is used,the grain-oriented silicon steel is used on stator teeth of the SynRMb(SynRMbG)was proposed and studied.The analysis results show that the proposed new method can make the SynRM have better performance.
基金Supported by National Natural Science Foundation of China(Grant No.51805141)Funds for Creative Research Groups of Hebei Province of China(Grant No.E2020202142)+2 种基金Tianjin Municipal Science and Technology Plan Project of China(Grant No.19ZXZNGX00100)Key R&D Program of Hebei Province of China(Grant No.19227208D)National Key Research and development Program of China(Grant No.2020YFB2009400).
文摘On-site and real-time non-destructive measurement of elastic constants for materials of a component in a in-service structure is a challenge due to structural complexities,such as ambiguous boundary,variable thickness,nonuniform material properties.This work develops for the first time a method that uses ultrasound echo groups and artificial neural network(ANN)for reliable on-site real-time identification of material parameters.The use of echo groups allows the use of lower frequencies,and hence more accommodative to structural complexity.To train the ANNs,a numerical model is established that is capable of computing the waveform of ultrasonic echo groups for any given set of material properties of a given structure.The waveform of an ultrasonic echo groups at an interest location on the surface the structure with material parameters varying in a predefined range are then computed using the numerical model.This results in a set of dataset for training the ANN model.Once the ANN is trained,the material parameters can be identified simultaneously using the actual measured echo waveform as input to the ANN.Intensive tests have been conducted both numerically and experimentally to evaluate the effectiveness and accuracy of the currently proposed method.The results show that the maximum identification error of numerical example is less than 2%,and the maximum identification error of experimental test is less than 7%.Compared with currently prevailing methods and equipment,the proposefy the density and thickness,in addition to the elastic constants.Moreover,the reliability and accuracy of inverse prediction is significantly improved.Thus,it has broad applications and enables real-time field measurements,which has not been fulfilled by any other available methods or equipment.
基金the National Natural Science Foundation of China(No.52072110)the Natural Science Foundation of Hebei Province,China(No.E2018202034).
文摘The Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)composite coatings were prepared by plasma spraying Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)and Al−Cr2O3−SiC composite powders,respectively.The microstructure,formation mechanism and properties of the two Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)composite coatings obtained by plasma spraying were investigated,and the reaction mechanism of the Al−Cr_(2)O_(3)−SiC system was explored.The results show that the coating obtained by plasma spraying Al−Cr_(2)O_(3)−SiC composite powders had thinner lamella and more tortuous interlayer interface,and the in-situ synthesized Cr_(7)C_(3),CrSi_(2) and Al_(2)O_(3) in the coating were all nano-crystallines.Compared with the Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)coating prepared by plasma spraying Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)composite powders,the plasma-sprayed Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)coating obtained from Al−Cr_(2)O_(3)−SiC composite powders had higher density,higher microhardness(increased by 20%),better fracture toughness and lower wear rate(reduced by 28%).
基金supported by the National Natural Science Foundation of China(61775004,61935016)the National Key Research and Development Program of China(2017YFA0206600)the National Natural Science Foundation of China(51773045,21772030,51922032,21961160720)for financial support.
文摘With great achievements in efficiency,stability,and large-scale preparation of perovskite solar cells(PSCs),the com-mercialization of PSC is ongoing,but there is still an issue on lead toxicity.Although lead content in the device is low,the water solubility of lead salts leads to potential environmental pollution.At present,the non-lead perovskites studied in-clude:divalent metal perovskite(e.g.,Sn^(2+),Ge^(2+),Cu^(2+)),trivalent metal perovskite(e.g.,Bi^(3+),Sb^(3+),In^(3+)),tetravalent met-al double perovskite(e.g.,Sn^(4+),Pd^(4+),Ti^(4+),Pt^(4+))and mono-trivalent mixed double perovskite(e.g.,Ag+and Bi^(3+),Ag+and In^(3+),Ag^(+)and Sb^(3+)).Their properties are summarized in Table 1.Since the first report on non-lead double perovskite Cs2AgBiBr6 in 2016^([1]).
基金Key Laboratory of Special Machine and High Voltage Apparatus,Ministry of Education,Grant/Award Number:KFKT202207the Natural Science Foundation of Hebei Province,Grant/Award Number:E2021521003Hebei Province Innovative Capacity Development Program for Research Students,Grant/Award Number:CXZZSS2023018。
文摘During the operation of high-voltage cables,external stress and residual stress can affect the aggregated structure of insulating materials and lead to significant deterioration in their electrical performance.To investigate the evolution characteristics of the electrical properties of cross-linked polyethylene(XLPE)under mechanical stress,this paper ex-plains the relationship between the aggregated structure of XLPE and its electrical properties and proposes a method for improving insulation performance under me-chanical stress.The results show that metallocene polyethylene used as a nucleating agent can promote crystallisation through heterogeneous nucleation and increase Young's modulus by non-uniform nucleation,increasing crystallinity and reducing interplanar spacing,resulting in more complete crystal forms and reduced damage to the aggregated structure during the tensile process.After nucleating agent modification,the XLPE crystallisation becomes more uniform,and interfacial adhesion forces increase.The weakened interface damage process between the amorphous and crystalline regions under tensile stress effectively inhibits the process of molecular chain polarisation turning and reduces trap density.The modified XLPE crystal structure shows a tendency towards densification and enhanced molecular chain interactions,which can reduce the damage to the aggregated structure under tensile stress,while the reduced free volume inside the material and the shortened average free path of carriers can weaken the damage of high-energy electrons to molecular chains,thereby inhibiting the process of electrical tree degradation.The results show that nucleating agents have great potential for maintaining the stable operation of XLPE cables under mechanical stress.
基金This work was supported in part by the National Natural Science Foundation of China(NO.51607157,51777055)the National Key R&D Program of China(NO.2017YFB0903904)+2 种基金the Key Scientific Research Project for Colleges and universities of Henan,China(NO.16A470017)the Hebei Province Science Foundation for Distinguished Young Scholars,Hebei,China(No.E2018202284)the Doctor Foundation of Zhengzhou University of Light Industry,Zhengzhou,Henan,China(NO.2015BSJJ012).
文摘This paper presents a method to study the vector magnetic properties of magnetic materials under alternating and rotational magnetic field using 2-D vector hybrid hysteresis model.Combining Preisach model and Stoner-Wohlfarth(S-W)model,the vector hybrid hysteresis model is established for magnetic materials.The alternating and rotational hysteresis properties are calculated under different excitation frequency,respectively.And the computed results are compared with the experimental measurement ones.It is shown that the vector model can simulate the alternating and rotational magnetic properties effectively under low magnetization fields and low excitation frequency.
基金This work was supported in part by the National Natural Science Foundation of China under project 51877065Hebei Province Education Department Youth Talent Leading Project under grant BJ2018037in part by the State Key Laboratory of Reliability and Intelligence of Electrical Equipment under grant EERIKF2018005.
文摘The performance of traditional flux switching permanent magnet tubular machine(FSPMTM)are improved by using new material and structure in this paper.The existing silicon steel sheet making for all mover cores or part of stator cores are replaced by soft magnetic composite(SMC)cores,and the lamination direction of the silicon steel sheet in stator cores have be changed.The eddy current loss of the machine with hybrid cores will be reduced greatly as the magnetic flux will not pass through the silicon steel sheet vertically.In order to reduce the influence of end effect,the unequal stator width design method is proposed.With the new design,the symmetry of the permanent magnet flux linkage has been improved greatly and the cogging force caused by the end effect has been reduced.Both 2-D and 3-D finite element methods(FEM)are applied for the quantitative analysis.
基金This work was supported in part by the National Natural Science Foundation of China under project 51877065Hebei Province Education Department Youth Talent Leading Project under grant BJ2018037.
文摘This paper proposes a new rotary flux switching transverse flux machine with the ability of linear motion(FSTFMaLM),in which both the stator and the rotor cores are made by using soft magnetic composite(SMC)materials.With the special design pattern,for the rotary motion model,the proposed machine can combine both the advantages of the flux switching permanent magnet machine(FSPMM)and the transverse flux machine(TFM).It can output with relatively high torque density,and as there is no windings or the magnets on the rotor cores,the proposed machine can operate in the high speed region to improve the output power.With the adoption of the SMC materials,the manufacturing of this machine can be quite easy.By stacking the rotor core together and prolong it with the determined length in the axial direction,in addition with the special control algorithm,the proposed machine can have the ability of the linear motion.In this paper,the operation principle of this machine has been explained and the design methods are also presented.To seek the better performance,the main dimension of the machine is optimized,and for the performance evaluation,the finite element method(FEM)is adopted.The proposed machine can be used for the electric driving systems,robotic systems or other applications where the linear motion ability is required.
基金Project supported by the National Natural Science Foundation of China(Grant No.51807050)the National Basic Research Program of China(Grant No.2015CB251002)the Program for the Top Young and Middle-aged Innovative Talents of Higher Learning Institutions of Hebei,China(Grant No.BJ2017038)
文摘A semi-empirical equation of state model for aluminum in a warm dense matter regime is constructed. The equation of state, which is subdivided into a cold term, thermal contributions of ions and electrons, covers a broad range of phase diagram from solid state to plasma state. The cold term and thermal contribution of ions are from the Bushman–Lomonosov model, in which several undetermined parameters are fitted based on equation of state theories and specific experimental data. The Thomas–Fermi–Kirzhnits model is employed to estimate the thermal contribution of electrons. Some practical modifications are introduced to the Thomas–Fermi–Kirzhnits model to improve the prediction of the equation of state model. Theoretical calculation of thermodynamic parameters, including phase diagram, curves of isothermal compression at ambient temperature, melting, and Hugoniot, are analyzed and compared with relevant experimental data and other theoretical evaluations.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.81830061 and 11605038)the Natural Science Foundation of Hebei Province of China(Grant No.A2020202007)the Natural Science Foundation of Tianjin of China(Grant No.19JCYBJC28300).
文摘Transient receptor potential vanilloid subtype 1 (TRPV1) is a polymodel sensory receptor and can be activated by moderate temperature (≥ 43 ℃). Though extensive researches on the heat-activation mechanism revealed some key elements that participate in the heat-sensation pathway, the detailed thermal-gating mechanism of TRPV1 is still unclear. We investigate the heat-activation process of TRPV1 channel using the molecular dynamics simulation method at different temperatures. It is found that the favored state of the supposed upper gate of TRPV1 cannot form constriction to ion permeation. Oscillation of S5 helix originated from thermal fluctuation and forming/breaking of two key hydrogen bonds can transmit to S6 helix through the hydrophobic contact between S5 and S6 helix. We propose that this is the pathway from heat sensor of TRPV1 to the opening of the lower gate. The heat-activation mechanism of TRPV1 presented in this work can help further functional study of TRPV1 channel.
