Permanently shadowed regions(PSRs)on the Moon are potential reservoirs for water ice,making them hot spots for future lunar exploration.The water ice in PSRs would cause distinctive changes in space weathering there,i...Permanently shadowed regions(PSRs)on the Moon are potential reservoirs for water ice,making them hot spots for future lunar exploration.The water ice in PSRs would cause distinctive changes in space weathering there,in particular reduction-oxidation processes that diff er from those in illuminated regions.To determine the characteristics of products formed during space weathering in PSRs,the lunar meteorite NWA 10203 with artifi cially added water was irradiated with a nanosecond laser to simulate a micro-meteorite bombardment of lunar soil containing water ice.The TEM results of the water-incorporated sample showed distinct amorphous rims that exhibited irregular thickness,poor stratifi cation,the appearance of bubbles,and a reduced number of npFe^(0).Additionally,EELS analysis showed the presence of ferric iron at the rim of the nanophase metallic iron particles(npFe^(0))in the amorphous rim with the involvement of water.The results suggest that water ice is another possible factor contributing to oxidation during micrometeorite bombardment on the lunar surface.In addition,it off ers a reference for a new space weathering model that incorporates water in PSRs,which could be widespread on asteroids with volatiles.展开更多
Traumatic axonal lesions of peripheral nerves disrupt neuronal connections with their targets,resulting in the loss of motor and sensory functions.Despite the peripheral nervous system’s capacity for axonal regrowth,...Traumatic axonal lesions of peripheral nerves disrupt neuronal connections with their targets,resulting in the loss of motor and sensory functions.Despite the peripheral nervous system’s capacity for axonal regrowth,this may lead to permanent impairements resulting in a loss of quality of life and a high socioeconomic burden.展开更多
This paper presents a high-fidelity lumpedparameter(LP)thermal model(HF-LPTM)for permanent magnet synchronous machines(PMSMs)in electric vehicle(EV)applications,where various cooling techniques are considered,includin...This paper presents a high-fidelity lumpedparameter(LP)thermal model(HF-LPTM)for permanent magnet synchronous machines(PMSMs)in electric vehicle(EV)applications,where various cooling techniques are considered,including frame forced air/liquid cooling,oil jet cooling for endwinding,and rotor shaft cooling.To address the temperature misestimation in the LP thermal modelling due to assumptions of concentrated loss input and uniform heat flows,the developed HF-LPTM introduces two compensation thermal resistances for the winding and PM components,which are analytically derived from the multi-dimensional heat transfer equations and are robust against different load/thermal conditions.As validated by the finite element analysis method and experiments,the conventional LPTMs exhibit significant winding temperature deviations,while the proposed HF-LPTM can accurately predict both the midpoint and average temperatures.The developed HFLPTM is further used to assess the effectiveness of various cooling techniques under different scenarios,i.e.,steady-state thermal states under the rated load condition,and transient temperature profiles under city,freeway,and hybrid(city+freeway)driving cycles.Results indicate that no single cooling technique can maintain both winding and PM temperatures within safety limits.The combination of frame liquid cooling and oil jet cooling for end winding can sufficiently mitigate PMSM thermal stress in EV applications.展开更多
Wireless capsule endoscopy(WCE)has the potential to fully replace conventional wired counterparts for its low invasiveness.Recent studies have attempted to expand the functions of capsules toward this goal.However,lim...Wireless capsule endoscopy(WCE)has the potential to fully replace conventional wired counterparts for its low invasiveness.Recent studies have attempted to expand the functions of capsules toward this goal.However,limitations in space and energy supply have resulted in the inability to perform multiple diagnostic and treatment tasks using a single capsule.In this study,we developed a dual-functional capsule robot(DFCR)for drug delivery and tissue biopsy based on magnetic torsion spring technology.The delivery module was shown to rotate the push rod with a thrust of 894 mN to release approximately 0.3 mL of semisolid drug.The biopsy module used a built-in blade to cut tissue with a shear stress of 22.87 MPa,producing a sample of approximately 1.8 mm3.Additionally,a five-degree-of-freedom permanent magnet drive system was developed.By adjusting the strength of the unidirectional magnetic field generated by an external magnet,the capsule can be wirelessly controlled to sequentially trigger the two functions.Ex vivo tests on porcine stomachs confirmed the feasibility of the prototype capsule(12 mm in diameter and 45 mm in length)in active movement,medication,and tissue biopsy.The newly developed DFCR further expands the clinical application prospects of WCE robots in minimally invasive surgery.展开更多
The combination of dual-main-phase(DMP)(Nd,Ce)-Fe-B magnets and grain boundary diffusion process(GBDP)is currently a research topic for obtaining high-cost performance materials in rare earth permanent magnet fields.T...The combination of dual-main-phase(DMP)(Nd,Ce)-Fe-B magnets and grain boundary diffusion process(GBDP)is currently a research topic for obtaining high-cost performance materials in rare earth permanent magnet fields.The novel structural features of GBDP(Nd,Ce)-Fe-B magnets give a version of different domain reversal processes from those of non-diffused magnets.In this work,the in-situ magnetic domain evolution of the DMP magnets was observed at elevated temperatures,and the temperature demagnetization and coercivity mechanism of the GBDP dual-main-phase(Nd,Ce)-Fe-B magnets are discussed.The results show that the shell composition of different types of grains in DMP magnets is similar,while the magnetic microstructure results indicate the Ce-rich grains tend to demagnetize first.Dy-rich shell with a high anisotropic field caused by GBDP leads to an increase in the nucleation field,which enhances the coercivity.It is found that much more grains exhibit single domain characteristics in the remanent state for GBDP dual-main-phase(Nd,Ce)-Fe-B magnets.In addition,the grains that undergo demagnetization first are Ce-rich or Nd-rich grains,which is different from that of non-diffused magnets.These results were not found in previous studies but can be intuitively characterized from the perspective of magnetic domains in this work,providing a new perspective and understanding of the performance improvement of magnetic materials.展开更多
Bedding parallel stepped rock slopes exist widely in nature and are used in slope engineering.They are characterized by complex topography and geological structure and are vulnerable to shattering under strong earthqu...Bedding parallel stepped rock slopes exist widely in nature and are used in slope engineering.They are characterized by complex topography and geological structure and are vulnerable to shattering under strong earthquakes.However,no previous studies have assessed the mechanisms underlying seismic failure in rock slopes.In this study,large-scale shaking table tests and numerical simulations were conducted to delineate the seismic failure mechanism in terms of acceleration,displacement,and earth pressure responses combined with shattering failure phenomena.The results reveal that acceleration response mutations usually occur within weak interlayers owing to their inferior performance,and these mutations may transform into potential sliding surfaces,thereby intensifying the nonlinear seismic response characteristics.Cumulative permanent displacements at the internal corners of the berms can induce quasi-rigid displacements at the external corners,leading to greater permanent displacements at the internal corners.Therefore,the internal corners are identified as the most susceptible parts of the slope.In addition,the concept of baseline offset was utilized to explain the mechanism of earth pressure responses,and the result indicates that residual earth pressures at the internal corners play a dominant role in causing deformation or shattering damage.Four evolutionary deformation phases characterize the processes of seismic responses and shattering failure of the bedding parallel stepped rock slope,i.e.the formation of tensile cracks at the internal corners of the berm,expansion of tensile cracks and bedding surface dislocation,development of vertical tensile cracks at the rear edge,and rock mass slipping leading to slope instability.Overall,this study provides a scientific basis for the seismic design of engineering slopes and offers valuable insights for further studies on preventing seismic disasters in bedding parallel stepped rock slopes.展开更多
Permanent magnet synchronous motor based electro-mechanical actuation servo drives have widespread applications in the aviation field,such as unmanned aerial vehicle electric servos,electric cabin doors,and mechanical...Permanent magnet synchronous motor based electro-mechanical actuation servo drives have widespread applications in the aviation field,such as unmanned aerial vehicle electric servos,electric cabin doors,and mechanical arms.The performance of the servo drive,which encompasses the response to the torque,efficiency,control bandwidth and the steady-state positioning accuracy,significantly influences the performance of the aviation actuation.Consequently,enhancing the control bandwidth and refining the positioning accuracy of aviation electro-mechanical actuation servo drives have emerged as a focal point of research.This paper investigates the multi-source disturbances present in aviation electro-mechanical actuation servo systems and summarizes recent research on high-performance servo control methods based on active disturbance rejection control(ADRC).We present a comprehensive overview of the research status pertaining to servo control architecture,strategies for suppressing disturbances in the current loop,and ADRC-based strategies for the position loop.We delineate the research challenges and difficulties encountered by aviation electro-mechanical actuation servo drive control technology.展开更多
The property IR was introduced by Friis and Rordam in 1996.They proved that any pair of almost commuting self-adjoint elements is norm close to a pair of exactly commuting self-adjoint elements in any C^(*)-algebras w...The property IR was introduced by Friis and Rordam in 1996.They proved that any pair of almost commuting self-adjoint elements is norm close to a pair of exactly commuting self-adjoint elements in any C^(*)-algebras with the property IR.In this paper,we will prove some permanence results for IR-algebras,approximate IR-algebras and local IR-algebras.Finally,we will also show that any pair of almost commuting self-adjoint elements is norm close to a pair of exactly commuting self-adjoint elements in any local IR-algebra.展开更多
The aim of this study is to address the issues associated with traditional magnetorheological fluid(MRF)dampers,such as insufficient damping force after power failure and susceptibility to settlement.In order to achie...The aim of this study is to address the issues associated with traditional magnetorheological fluid(MRF)dampers,such as insufficient damping force after power failure and susceptibility to settlement.In order to achieve this,a bidirectional adjustable MRF damper was designed and developed.Magnetic field simulation analysis was conducted on the damper,along with simulation analysis on its dynamic characteristics.The dynamic characteristics were ultimately validated through experimental testing on the material testing machine,thereby corroborating the theoretical simulation results.Concurrently,this process generated valuable test data for subsequent implementation of the semi-active vibration control system.The simulation and test results demonstrate that the integrated permanent magnet effectively accomplishes bidirectional regulation.The magnetic induction intensity of the damping channel is 0.2 T in the absence of current,increases to 0.5 T when a maximum forward current of 4 A is applied,and becomes 0 T when a maximum reverse current of 3.8 A is applied.When the excitation amplitude is 8 mm and the frequency is 2 Hz,with the applied currents varying,the maximum damping force reaches 8 kN,while the minimum damping force measures at 511 N.Additionally,at zero current,the damping force stands at 2 kN,which aligns closely with simulation results.The present paper can serve as a valuable reference for the design and research of semi-active MRF dampers.展开更多
Permanent magnet synchronous motor(PMSM),known for their compact size and high-power density,is widely used in fields such as electric vehicles and servo drives.However,traditional PID control methods for PMSM cannot ...Permanent magnet synchronous motor(PMSM),known for their compact size and high-power density,is widely used in fields such as electric vehicles and servo drives.However,traditional PID control methods for PMSM cannot dynamically adjust parameters according to varying operating conditions.To address this issue,this paper proposes a PID control method based on a radial basis function(RBF)neural network,which adaptively tunes the PID controller parameters.First,an offline RBF neural network with optimal structural parameters is trained using the current and speed data of the PMSM,and then employed to construct the RBF-PID controller.During online training,the Jacobian information calculated via the RBF neural network is used to adaptively adjust the PID parameters.Simultaneously,the structural parameters of the RBF network are updated in reverse based on the error between the predicted and reference speed values.Finally,numerical simulations and experiments in the context of electric vehicle drive control show that the maximum speed errors of the SMC controller and the RBF-PID controller are 1.97 km/h and 0.17 km/h,respectively.Moreover,the RBF-PID controller outperforms both the SMC and traditional PID controllers in handling sudden speed changes.展开更多
Permanent dipole moments induced high-order harmonic generation(HHG)signals offer a potential approach to producing elliptically or even circularly polarized X-ray attosecond sources.Previous studies on this topic hav...Permanent dipole moments induced high-order harmonic generation(HHG)signals offer a potential approach to producing elliptically or even circularly polarized X-ray attosecond sources.Previous studies on this topic have mainly focused on diatomic molecules such as CO and HeH.Based on this scheme,significant HHG signals in the direction perpendicular to the molecular axis can be observed in both the high-energy and low-energy regions.However,we found that the high-order harmonics induced by the permanent dipole moments of polyatomic complex molecules involve more intricate physical processes.Using time-dependent density functional theory,we simulated the dynamics of HHG from NH2COOH and NH2COSH interacting with linearly polarized lasers.We found that the harmonic signals in the direction perpendicular to the N-C bond were significantly enhanced in the high-energy photon region.Our analysis indicates that this is due to the complex molecular configuration of NH_(2)COOH and NH_(2)COSH:while the NH_(2) group has C_(2v) symmetry,both COOH and COSH groups lack this symmetry.This structural characteristic results in permanent dipole moments being felt only when electrons return to either COSH or COOH groups,but not to NH_(2) group.Additionally,our results reveal a multi-plateau structure in HHG signal along laser polarization direction,a phenomenon arising from multi-electron and multiorbital effects during interaction between complex molecule and strong laser field.展开更多
We proposed a new measure to optimize the comprehensive magnetic properties of SmCo_(5)alloy.By compounding Fe-15Ni-3Al-1Ti(FNAT)alloy with high saturation magnetization and Sm(Co,Cu)_(5) matrix alloy in the liquid st...We proposed a new measure to optimize the comprehensive magnetic properties of SmCo_(5)alloy.By compounding Fe-15Ni-3Al-1Ti(FNAT)alloy with high saturation magnetization and Sm(Co,Cu)_(5) matrix alloy in the liquid state,an innovative two-phase separation microstructure or cellular microstructure is formed after melt-spinning using the phase separation effect of the two alloys.At the same time,the element concentration,relative phase content,and microstructure are adjusted by adding different contents of FNAT alloy.The results show that FNAT addition promotes the as-spun ribbons phase separation(or spinodal decomposition)into Co-rich SmCo_(5)-and Sm-Ni-rich CeCo_(5)-or Sm_(2)Co_(7)-type phases.Adding 3 wt.%FNAT increases the coercivity,saturation magnetization,and remanence of the ribbons by 320.6%,39.8%,and 82.8%,respectively.Adding 5 wt.%FNAT promotes forming the Sm_(2)(Co,M)_(7) cell-wall phase and increases the coercivity and remanence by 272.7%and 48.1%,respectively.Finally,the corresponding microstructure evolution models,magnetization,and demagnetization mechanisms are proposed.展开更多
ThMn_(12)-type iron-rich rare-earth permanent magnetic materials have garnered significant attention due to their exceptional intrinsic magnetic properties.However,challenges such as the metastable nature of the ThMn1...ThMn_(12)-type iron-rich rare-earth permanent magnetic materials have garnered significant attention due to their exceptional intrinsic magnetic properties.However,challenges such as the metastable nature of the ThMn12-type phase,excessively small single-domain grain size,and complex fabrication processes have hindered the achievement of high phase purity,uniform microstructure,and desirable extrinsic performance.In this study,we directly synthesized ThMn_(12)-type Sm_(0.8)Zr_(0.2)Fe_(11)SiB_(x)(x=0-0.2)ribbon magnets via boron doping combined with a one-step rapid solidification method.This approach not only simplifies the fabrication process but also enhances phase stability and achieves a uniform microstructure with high ThMn12-type phase purity.By optimizing the boron content and cooling rate,the resulting magnets exhibit a coercivity(H_(c))of 6222 Oe,a remanence(M_(r))of 80 emu/g,and a remanence ratio(M_(r)/M_(s))of 0.71.This work demonstrates a streamlined approach to producing high-performance ThMn12-type magnets and provides insights into their practical application potential.展开更多
In permanent magnet synchronous machine(PMSM) drives, temperature information is critical to achieve reliable and high-performance control. The popular model-based estimation methods are based on extracting temperatur...In permanent magnet synchronous machine(PMSM) drives, temperature information is critical to achieve reliable and high-performance control. The popular model-based estimation methods are based on extracting temperature dependent terms from the voltages using the machine model. The estimation accuracy under low speed or load can be greatly affected by the model uncertainty and noise due to low signal-tonoise ratio. This paper presents a high frequency(HF) position offset injection-based winding and permanent magnet(PM) temperature decoupled estimation approach for PMSMs to achieve accurate and robust temperature estimation among a wide speed range especially under low-speed conditions. In the proposed approach, a small HF position offset is injected into the machine to construct a decoupled winding and PM temperature estimation model, in which the winding and PM temperatures are independently estimated from HF excitations. The temperature estimation is independent from the fundamental model and parameter variation, and it achieves high signal-tonoise ratio under low-speed conditions. Moreover, the temperature estimation is also not affected by magnetic saturation and inverter distortion, which can improve the accuracy and robustness of temperature estimation. The proposed approach is validated with experiments and comparisons on a laboratory machine under various operating conditions.展开更多
Objective:To investigate the distribution of health literacy(HL)levels and the association of HL with proactive personality in patients with permanent colostomy.Methods:A cross-sectional study was conducted to measure...Objective:To investigate the distribution of health literacy(HL)levels and the association of HL with proactive personality in patients with permanent colostomy.Methods:A cross-sectional study was conducted to measure proactive personality and HL using validated scales.A total of 172 patients with permanent colostomy were selected from January 2021 to May 2022 in Yantai City,China.Descriptive statistics,t-test,ANOVA,Pearson correlation analysis,and multiple linear regression analysis techniques were used.Results:The results obtained from the study showed that the HL status of the participants was moderate.The correlation between participants’total HL scores and proactive personality scores was 0.417(P-value<0.001).In addition,HL showed statistically significant differences according to education level,place of residence,profession,and average monthly household income.Conclusions:This study showed that patients with higher proactive personality scores had higher HL.The key stakeholders require several positive strategies to improve the HL of patients with permanent colostomy by cultivating their proactive personalities,and these important policies will help to improve patient health and quality of life.展开更多
In this work, nanocrystalline SmCo_(5)-Cu nanocomposite powders were fabricated from the ball-milled amorphous matrix by crystallization annealing which is lower than the traditional sintering temperature ~ 1000℃ for...In this work, nanocrystalline SmCo_(5)-Cu nanocomposite powders were fabricated from the ball-milled amorphous matrix by crystallization annealing which is lower than the traditional sintering temperature ~ 1000℃ for bulk SmCo_(5) bulk magnets. Annealed Cu-doped SmCo_(5) powders have a higher coercivity compared to that of Cu-free SmCo_(5) one due to the combined effects of refinement effect of grain size and the pinning effect induced by Cu doping. The peak of coercivity (Hc) is located at 600℃ for annealed Cu-doped SmCo_(5), which is ascribed to the improved pinning field. The pinning effect became reduced when the annealing was done at even higher temperatures. More importantly, the best comprehensive magnetic properties, including a maximum magnetic energy product (BH)max of 12.2 MGOe together with a coercivity of 31.8 kOe and a remanence of 64.3 emu/g, could be achieved for SmCo_(5)-3 wt% Cu by low temperature annealing. These results demonstrate that isotropic Cu-doped SmCo_(5) nanocrystalline powders are promising precursors for the fabrication of high-performance bulk magnets.展开更多
BACKGROUND Autoimmune myocarditis(AM)associated with autoimmune diseases can cause complete atrioventricular block(CAVB),but the related autoantigens and the underlying mechanisms are unclear.Anti-SSA/Ro antibodies ma...BACKGROUND Autoimmune myocarditis(AM)associated with autoimmune diseases can cause complete atrioventricular block(CAVB),but the related autoantigens and the underlying mechanisms are unclear.Anti-SSA/Ro antibodies may play an important role in this process,but cases of AM with positive anti-SSA/Ro antibodies are rare.In addition,arrhythmias,such as atrioventricular block,are very common in patients with autoimmune diseases,but severe atrioventricular block requiring permanent pacemaker implantation is extremely rare.CASE SUMMARY The patient in this case had AM with anti-SSA/Ro antibody positivity,which was associated with connective tissue disease,and the patient subsequently developed CAVB.After intensive immunosuppressive therapy,the antibody test results became negative,and pulmonary hypertension significantly improved.However,the outcome of permanent pacemaker implantation did not change.CONCLUSION In clinical practice,the awareness of adult AM associated with autoimmune diseases combined with CAVB should be strengthened in clinicians,and anti-SSA/Ro antibodies may play a role in this process.Therefore,improving the detection of antibodies and early intervention,such as active immunosuppression therapy,may be very important for improving disease prognosis.For patients who do not respond to immunosuppressive therapy,implantation of a permanent pacemaker may become an essential treatment option.展开更多
The arc-linear motor(ALM) is a new type of special motor derived from the linear motor, which has the merits of high torque, compact structure and fast dynamic response. This kind of motor does not need a complex inte...The arc-linear motor(ALM) is a new type of special motor derived from the linear motor, which has the merits of high torque, compact structure and fast dynamic response. This kind of motor does not need a complex intermediate transmission device, it is used in some direct-drive applications for continuous rotation or limited angle motion. However, there is no systematic summary and generalization of the ALMs so far.Therefore, this paper systematically overviews the recent advances in ALMs for direct-drive systems. First, the evolution process and basic structure of the ALM are introduced. And then, various ALMs are reviewed with particular reference to motor topologies, working principle, motor performance,optimization design and control techniques. To heel, a comprehensive comparison of several typical ALMs is carried out. Finally, the application areas, main challenges and development trends of the ALMs are highlighted.展开更多
Purpose:To describe the characteristics of research outputs using persistent identifiers generated by ResearchGate to gain insight into what publications are shared and disseminated through this functionality,revealin...Purpose:To describe the characteristics of research outputs using persistent identifiers generated by ResearchGate to gain insight into what publications are shared and disseminated through this functionality,revealing their academic and non-academic impact.Design/methodology/approach:A total of 1,092,934 RG-DOIs were collected,using the DataCite API,along with bibliographic metadata for the associated registered output(RG-DOI publications).The subsequent analysis evaluated the publication date,document type,and language.These values were crossreferenced against the full text of a random sample of 666 records to verify accuracy.Findings:RG-DOIs have served primarily to identify and make accessible scholarly gray literature,including posters,presentations,conference papers,and theses,with notable emphasis on publications in Spanish and Portuguese.Around 41,000 citations from Web of Science indexed publications to RG publications are evidence of their infrequent but perceptible use in scholarly discourse.The declining number of registrations of RG-DOIs observed may indicate a shift in researcher preferences to alternative platforms for DOI generation.Research limitations:The study uncovered substantial inconsistencies in DataCite metadata,which can be attributed to the automated DOI registration process and internal changes in the available document types on ResearchGate.Practical implications:The study encountered challenges in conducting a quantitative analysis due to inconsistencies in the metadata.These have potential implications for researchers,practitioners,and librarians relying on RG-DOIs to conduct bibliometric or bibliographic analysis.Originality/value:This study is the first comprehensive analysis of RG-DOIs and,as such,provides a unique perspective into academic gray literature.It also sheds light on the quality of ResearchGate data transmitted to DataCite when registering DOIs.展开更多
基金support from the Youth Innovation Promotion Association,Chinese Academy of Sciences(2020395)Strategic Priority Research Program of the Chinese Academy of Sciences grant XDB 41000000(Y.L.)+4 种基金National Natural Science Foundation of China(Nos.42273042 and 41931077)"From 0 to 1"Original Exploration Cultivation Project,Institute of Geochemistry,Chinese Academy of Sciences(DHSZZ2023-3)Guizhou Provincial Foundation for Excellent Scholars Program(No.GCC[2023]088)Guizhou Provincial Science and Technology Projects:QKHJCZK[2023]-General 473NSFC Young Scientist Fund(Nos.42303041 and 42403043)。
文摘Permanently shadowed regions(PSRs)on the Moon are potential reservoirs for water ice,making them hot spots for future lunar exploration.The water ice in PSRs would cause distinctive changes in space weathering there,in particular reduction-oxidation processes that diff er from those in illuminated regions.To determine the characteristics of products formed during space weathering in PSRs,the lunar meteorite NWA 10203 with artifi cially added water was irradiated with a nanosecond laser to simulate a micro-meteorite bombardment of lunar soil containing water ice.The TEM results of the water-incorporated sample showed distinct amorphous rims that exhibited irregular thickness,poor stratifi cation,the appearance of bubbles,and a reduced number of npFe^(0).Additionally,EELS analysis showed the presence of ferric iron at the rim of the nanophase metallic iron particles(npFe^(0))in the amorphous rim with the involvement of water.The results suggest that water ice is another possible factor contributing to oxidation during micrometeorite bombardment on the lunar surface.In addition,it off ers a reference for a new space weathering model that incorporates water in PSRs,which could be widespread on asteroids with volatiles.
文摘Traumatic axonal lesions of peripheral nerves disrupt neuronal connections with their targets,resulting in the loss of motor and sensory functions.Despite the peripheral nervous system’s capacity for axonal regrowth,this may lead to permanent impairements resulting in a loss of quality of life and a high socioeconomic burden.
文摘This paper presents a high-fidelity lumpedparameter(LP)thermal model(HF-LPTM)for permanent magnet synchronous machines(PMSMs)in electric vehicle(EV)applications,where various cooling techniques are considered,including frame forced air/liquid cooling,oil jet cooling for endwinding,and rotor shaft cooling.To address the temperature misestimation in the LP thermal modelling due to assumptions of concentrated loss input and uniform heat flows,the developed HF-LPTM introduces two compensation thermal resistances for the winding and PM components,which are analytically derived from the multi-dimensional heat transfer equations and are robust against different load/thermal conditions.As validated by the finite element analysis method and experiments,the conventional LPTMs exhibit significant winding temperature deviations,while the proposed HF-LPTM can accurately predict both the midpoint and average temperatures.The developed HFLPTM is further used to assess the effectiveness of various cooling techniques under different scenarios,i.e.,steady-state thermal states under the rated load condition,and transient temperature profiles under city,freeway,and hybrid(city+freeway)driving cycles.Results indicate that no single cooling technique can maintain both winding and PM temperatures within safety limits.The combination of frame liquid cooling and oil jet cooling for end winding can sufficiently mitigate PMSM thermal stress in EV applications.
基金supported by the National Natural Science Foundation of China(No.52105072)Zhejiang Provincial Natural Science Foundation of China(No.LZ24E050004)+2 种基金Jiangsu Provincial Outstanding Youth Program(No.BK20230072)a grant from Suzhou Industrial Foresight and Key Core Technology Project(No.SYC2022044)grants from Jiangsu Qinglan Project and Jiangsu 333 High-level Talents.
文摘Wireless capsule endoscopy(WCE)has the potential to fully replace conventional wired counterparts for its low invasiveness.Recent studies have attempted to expand the functions of capsules toward this goal.However,limitations in space and energy supply have resulted in the inability to perform multiple diagnostic and treatment tasks using a single capsule.In this study,we developed a dual-functional capsule robot(DFCR)for drug delivery and tissue biopsy based on magnetic torsion spring technology.The delivery module was shown to rotate the push rod with a thrust of 894 mN to release approximately 0.3 mL of semisolid drug.The biopsy module used a built-in blade to cut tissue with a shear stress of 22.87 MPa,producing a sample of approximately 1.8 mm3.Additionally,a five-degree-of-freedom permanent magnet drive system was developed.By adjusting the strength of the unidirectional magnetic field generated by an external magnet,the capsule can be wirelessly controlled to sequentially trigger the two functions.Ex vivo tests on porcine stomachs confirmed the feasibility of the prototype capsule(12 mm in diameter and 45 mm in length)in active movement,medication,and tissue biopsy.The newly developed DFCR further expands the clinical application prospects of WCE robots in minimally invasive surgery.
基金supported by the National Key Research and Development Program of China(Nos.2021YFB3503003,2021YFB3503100,and 2022YFB3505401).
文摘The combination of dual-main-phase(DMP)(Nd,Ce)-Fe-B magnets and grain boundary diffusion process(GBDP)is currently a research topic for obtaining high-cost performance materials in rare earth permanent magnet fields.The novel structural features of GBDP(Nd,Ce)-Fe-B magnets give a version of different domain reversal processes from those of non-diffused magnets.In this work,the in-situ magnetic domain evolution of the DMP magnets was observed at elevated temperatures,and the temperature demagnetization and coercivity mechanism of the GBDP dual-main-phase(Nd,Ce)-Fe-B magnets are discussed.The results show that the shell composition of different types of grains in DMP magnets is similar,while the magnetic microstructure results indicate the Ce-rich grains tend to demagnetize first.Dy-rich shell with a high anisotropic field caused by GBDP leads to an increase in the nucleation field,which enhances the coercivity.It is found that much more grains exhibit single domain characteristics in the remanent state for GBDP dual-main-phase(Nd,Ce)-Fe-B magnets.In addition,the grains that undergo demagnetization first are Ce-rich or Nd-rich grains,which is different from that of non-diffused magnets.These results were not found in previous studies but can be intuitively characterized from the perspective of magnetic domains in this work,providing a new perspective and understanding of the performance improvement of magnetic materials.
基金supported by the National Natural Science Foundation of China (Grant No.52108361)the Sichuan Science and Technology Program of China (Grant No.2023YFS0436)the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project (Grant No.SKLGP2022Z015).
文摘Bedding parallel stepped rock slopes exist widely in nature and are used in slope engineering.They are characterized by complex topography and geological structure and are vulnerable to shattering under strong earthquakes.However,no previous studies have assessed the mechanisms underlying seismic failure in rock slopes.In this study,large-scale shaking table tests and numerical simulations were conducted to delineate the seismic failure mechanism in terms of acceleration,displacement,and earth pressure responses combined with shattering failure phenomena.The results reveal that acceleration response mutations usually occur within weak interlayers owing to their inferior performance,and these mutations may transform into potential sliding surfaces,thereby intensifying the nonlinear seismic response characteristics.Cumulative permanent displacements at the internal corners of the berms can induce quasi-rigid displacements at the external corners,leading to greater permanent displacements at the internal corners.Therefore,the internal corners are identified as the most susceptible parts of the slope.In addition,the concept of baseline offset was utilized to explain the mechanism of earth pressure responses,and the result indicates that residual earth pressures at the internal corners play a dominant role in causing deformation or shattering damage.Four evolutionary deformation phases characterize the processes of seismic responses and shattering failure of the bedding parallel stepped rock slope,i.e.the formation of tensile cracks at the internal corners of the berm,expansion of tensile cracks and bedding surface dislocation,development of vertical tensile cracks at the rear edge,and rock mass slipping leading to slope instability.Overall,this study provides a scientific basis for the seismic design of engineering slopes and offers valuable insights for further studies on preventing seismic disasters in bedding parallel stepped rock slopes.
基金supported by the National Natural Science Foundation of China(Nos.52177059 and 52407064).
文摘Permanent magnet synchronous motor based electro-mechanical actuation servo drives have widespread applications in the aviation field,such as unmanned aerial vehicle electric servos,electric cabin doors,and mechanical arms.The performance of the servo drive,which encompasses the response to the torque,efficiency,control bandwidth and the steady-state positioning accuracy,significantly influences the performance of the aviation actuation.Consequently,enhancing the control bandwidth and refining the positioning accuracy of aviation electro-mechanical actuation servo drives have emerged as a focal point of research.This paper investigates the multi-source disturbances present in aviation electro-mechanical actuation servo systems and summarizes recent research on high-performance servo control methods based on active disturbance rejection control(ADRC).We present a comprehensive overview of the research status pertaining to servo control architecture,strategies for suppressing disturbances in the current loop,and ADRC-based strategies for the position loop.We delineate the research challenges and difficulties encountered by aviation electro-mechanical actuation servo drive control technology.
基金Supported by NSFC(No.11401256)Scientific Research Fund of Zhejiang Provincial Education Department(No.Y202249575)Zhejiang Provincial NSF(No.LQ13A010016).
文摘The property IR was introduced by Friis and Rordam in 1996.They proved that any pair of almost commuting self-adjoint elements is norm close to a pair of exactly commuting self-adjoint elements in any C^(*)-algebras with the property IR.In this paper,we will prove some permanence results for IR-algebras,approximate IR-algebras and local IR-algebras.Finally,we will also show that any pair of almost commuting self-adjoint elements is norm close to a pair of exactly commuting self-adjoint elements in any local IR-algebra.
文摘The aim of this study is to address the issues associated with traditional magnetorheological fluid(MRF)dampers,such as insufficient damping force after power failure and susceptibility to settlement.In order to achieve this,a bidirectional adjustable MRF damper was designed and developed.Magnetic field simulation analysis was conducted on the damper,along with simulation analysis on its dynamic characteristics.The dynamic characteristics were ultimately validated through experimental testing on the material testing machine,thereby corroborating the theoretical simulation results.Concurrently,this process generated valuable test data for subsequent implementation of the semi-active vibration control system.The simulation and test results demonstrate that the integrated permanent magnet effectively accomplishes bidirectional regulation.The magnetic induction intensity of the damping channel is 0.2 T in the absence of current,increases to 0.5 T when a maximum forward current of 4 A is applied,and becomes 0 T when a maximum reverse current of 3.8 A is applied.When the excitation amplitude is 8 mm and the frequency is 2 Hz,with the applied currents varying,the maximum damping force reaches 8 kN,while the minimum damping force measures at 511 N.Additionally,at zero current,the damping force stands at 2 kN,which aligns closely with simulation results.The present paper can serve as a valuable reference for the design and research of semi-active MRF dampers.
文摘Permanent magnet synchronous motor(PMSM),known for their compact size and high-power density,is widely used in fields such as electric vehicles and servo drives.However,traditional PID control methods for PMSM cannot dynamically adjust parameters according to varying operating conditions.To address this issue,this paper proposes a PID control method based on a radial basis function(RBF)neural network,which adaptively tunes the PID controller parameters.First,an offline RBF neural network with optimal structural parameters is trained using the current and speed data of the PMSM,and then employed to construct the RBF-PID controller.During online training,the Jacobian information calculated via the RBF neural network is used to adaptively adjust the PID parameters.Simultaneously,the structural parameters of the RBF network are updated in reverse based on the error between the predicted and reference speed values.Finally,numerical simulations and experiments in the context of electric vehicle drive control show that the maximum speed errors of the SMC controller and the RBF-PID controller are 1.97 km/h and 0.17 km/h,respectively.Moreover,the RBF-PID controller outperforms both the SMC and traditional PID controllers in handling sudden speed changes.
基金supported by the Fundamental Research Funds for the Central Universities(Grant Nos.GK202207012 and QCYRCXM-2022-241).
文摘Permanent dipole moments induced high-order harmonic generation(HHG)signals offer a potential approach to producing elliptically or even circularly polarized X-ray attosecond sources.Previous studies on this topic have mainly focused on diatomic molecules such as CO and HeH.Based on this scheme,significant HHG signals in the direction perpendicular to the molecular axis can be observed in both the high-energy and low-energy regions.However,we found that the high-order harmonics induced by the permanent dipole moments of polyatomic complex molecules involve more intricate physical processes.Using time-dependent density functional theory,we simulated the dynamics of HHG from NH2COOH and NH2COSH interacting with linearly polarized lasers.We found that the harmonic signals in the direction perpendicular to the N-C bond were significantly enhanced in the high-energy photon region.Our analysis indicates that this is due to the complex molecular configuration of NH_(2)COOH and NH_(2)COSH:while the NH_(2) group has C_(2v) symmetry,both COOH and COSH groups lack this symmetry.This structural characteristic results in permanent dipole moments being felt only when electrons return to either COSH or COOH groups,but not to NH_(2) group.Additionally,our results reveal a multi-plateau structure in HHG signal along laser polarization direction,a phenomenon arising from multi-electron and multiorbital effects during interaction between complex molecule and strong laser field.
基金supported by the General Program from the National Natural Science Foundation of China(NNSFC)(No.52371185)Central Government Guides Local Funds for Science and Technology Development(No.216Z1008G)the Natural Science Foundation of Hebei province,China(No.E2022202017).
文摘We proposed a new measure to optimize the comprehensive magnetic properties of SmCo_(5)alloy.By compounding Fe-15Ni-3Al-1Ti(FNAT)alloy with high saturation magnetization and Sm(Co,Cu)_(5) matrix alloy in the liquid state,an innovative two-phase separation microstructure or cellular microstructure is formed after melt-spinning using the phase separation effect of the two alloys.At the same time,the element concentration,relative phase content,and microstructure are adjusted by adding different contents of FNAT alloy.The results show that FNAT addition promotes the as-spun ribbons phase separation(or spinodal decomposition)into Co-rich SmCo_(5)-and Sm-Ni-rich CeCo_(5)-or Sm_(2)Co_(7)-type phases.Adding 3 wt.%FNAT increases the coercivity,saturation magnetization,and remanence of the ribbons by 320.6%,39.8%,and 82.8%,respectively.Adding 5 wt.%FNAT promotes forming the Sm_(2)(Co,M)_(7) cell-wall phase and increases the coercivity and remanence by 272.7%and 48.1%,respectively.Finally,the corresponding microstructure evolution models,magnetization,and demagnetization mechanisms are proposed.
基金Project supported by the National Key R&D Program of China(Grant Nos.2021YFB3500300 and 2023YFB3507000)the Scientific Research Foundation of the High Education Institutions for Distinguished Young Scholars in Anhui Province(Grant No.2022AH020012)+1 种基金partially supported by the Innovation Project for Overseas Researcher in Anhui Province(Grant No.2022LCX004)the facilities at the Center of Free Electron Laser&High Magnetic Field(FEL&HMF)in Anhui University。
文摘ThMn_(12)-type iron-rich rare-earth permanent magnetic materials have garnered significant attention due to their exceptional intrinsic magnetic properties.However,challenges such as the metastable nature of the ThMn12-type phase,excessively small single-domain grain size,and complex fabrication processes have hindered the achievement of high phase purity,uniform microstructure,and desirable extrinsic performance.In this study,we directly synthesized ThMn_(12)-type Sm_(0.8)Zr_(0.2)Fe_(11)SiB_(x)(x=0-0.2)ribbon magnets via boron doping combined with a one-step rapid solidification method.This approach not only simplifies the fabrication process but also enhances phase stability and achieves a uniform microstructure with high ThMn12-type phase purity.By optimizing the boron content and cooling rate,the resulting magnets exhibit a coercivity(H_(c))of 6222 Oe,a remanence(M_(r))of 80 emu/g,and a remanence ratio(M_(r)/M_(s))of 0.71.This work demonstrates a streamlined approach to producing high-performance ThMn12-type magnets and provides insights into their practical application potential.
基金supported by Shenzhen Science and Technology Program under Grant JCYJ20250604175412017the National Natural Science Foundation of China under Grant 62473387+1 种基金the Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) under Grant SML2024SP007in part by the Department of Science and Technology of Guangdong Province under Grant. 2021QN020085。
文摘In permanent magnet synchronous machine(PMSM) drives, temperature information is critical to achieve reliable and high-performance control. The popular model-based estimation methods are based on extracting temperature dependent terms from the voltages using the machine model. The estimation accuracy under low speed or load can be greatly affected by the model uncertainty and noise due to low signal-tonoise ratio. This paper presents a high frequency(HF) position offset injection-based winding and permanent magnet(PM) temperature decoupled estimation approach for PMSMs to achieve accurate and robust temperature estimation among a wide speed range especially under low-speed conditions. In the proposed approach, a small HF position offset is injected into the machine to construct a decoupled winding and PM temperature estimation model, in which the winding and PM temperatures are independently estimated from HF excitations. The temperature estimation is independent from the fundamental model and parameter variation, and it achieves high signal-tonoise ratio under low-speed conditions. Moreover, the temperature estimation is also not affected by magnetic saturation and inverter distortion, which can improve the accuracy and robustness of temperature estimation. The proposed approach is validated with experiments and comparisons on a laboratory machine under various operating conditions.
文摘Objective:To investigate the distribution of health literacy(HL)levels and the association of HL with proactive personality in patients with permanent colostomy.Methods:A cross-sectional study was conducted to measure proactive personality and HL using validated scales.A total of 172 patients with permanent colostomy were selected from January 2021 to May 2022 in Yantai City,China.Descriptive statistics,t-test,ANOVA,Pearson correlation analysis,and multiple linear regression analysis techniques were used.Results:The results obtained from the study showed that the HL status of the participants was moderate.The correlation between participants’total HL scores and proactive personality scores was 0.417(P-value<0.001).In addition,HL showed statistically significant differences according to education level,place of residence,profession,and average monthly household income.Conclusions:This study showed that patients with higher proactive personality scores had higher HL.The key stakeholders require several positive strategies to improve the HL of patients with permanent colostomy by cultivating their proactive personalities,and these important policies will help to improve patient health and quality of life.
基金supported by the National Key Research and Development Program of China(Grant No.2023YFB3507600)the National Natural Science Foundation of China(Nos.U23A20549 and 52171184).
文摘In this work, nanocrystalline SmCo_(5)-Cu nanocomposite powders were fabricated from the ball-milled amorphous matrix by crystallization annealing which is lower than the traditional sintering temperature ~ 1000℃ for bulk SmCo_(5) bulk magnets. Annealed Cu-doped SmCo_(5) powders have a higher coercivity compared to that of Cu-free SmCo_(5) one due to the combined effects of refinement effect of grain size and the pinning effect induced by Cu doping. The peak of coercivity (Hc) is located at 600℃ for annealed Cu-doped SmCo_(5), which is ascribed to the improved pinning field. The pinning effect became reduced when the annealing was done at even higher temperatures. More importantly, the best comprehensive magnetic properties, including a maximum magnetic energy product (BH)max of 12.2 MGOe together with a coercivity of 31.8 kOe and a remanence of 64.3 emu/g, could be achieved for SmCo_(5)-3 wt% Cu by low temperature annealing. These results demonstrate that isotropic Cu-doped SmCo_(5) nanocrystalline powders are promising precursors for the fabrication of high-performance bulk magnets.
文摘BACKGROUND Autoimmune myocarditis(AM)associated with autoimmune diseases can cause complete atrioventricular block(CAVB),but the related autoantigens and the underlying mechanisms are unclear.Anti-SSA/Ro antibodies may play an important role in this process,but cases of AM with positive anti-SSA/Ro antibodies are rare.In addition,arrhythmias,such as atrioventricular block,are very common in patients with autoimmune diseases,but severe atrioventricular block requiring permanent pacemaker implantation is extremely rare.CASE SUMMARY The patient in this case had AM with anti-SSA/Ro antibody positivity,which was associated with connective tissue disease,and the patient subsequently developed CAVB.After intensive immunosuppressive therapy,the antibody test results became negative,and pulmonary hypertension significantly improved.However,the outcome of permanent pacemaker implantation did not change.CONCLUSION In clinical practice,the awareness of adult AM associated with autoimmune diseases combined with CAVB should be strengthened in clinicians,and anti-SSA/Ro antibodies may play a role in this process.Therefore,improving the detection of antibodies and early intervention,such as active immunosuppression therapy,may be very important for improving disease prognosis.For patients who do not respond to immunosuppressive therapy,implantation of a permanent pacemaker may become an essential treatment option.
基金supported in part by the National Natural Science Foundation of China under Grants 52307049 and U23A20644in part by the Fundamental Research Funds for the Central Universities under Grant JZ2023HGTB0243+1 种基金in part by the Key Laboratory of Electric Drive and Control of Anhui Province under Grant DQKJ202403in part by the China Postdoctoral Science Foundation under Grant 2024M751073。
文摘The arc-linear motor(ALM) is a new type of special motor derived from the linear motor, which has the merits of high torque, compact structure and fast dynamic response. This kind of motor does not need a complex intermediate transmission device, it is used in some direct-drive applications for continuous rotation or limited angle motion. However, there is no systematic summary and generalization of the ALMs so far.Therefore, this paper systematically overviews the recent advances in ALMs for direct-drive systems. First, the evolution process and basic structure of the ALM are introduced. And then, various ALMs are reviewed with particular reference to motor topologies, working principle, motor performance,optimization design and control techniques. To heel, a comprehensive comparison of several typical ALMs is carried out. Finally, the application areas, main challenges and development trends of the ALMs are highlighted.
基金supported by Grant PID2022-142569NA-I00,funded by MCIN/AEI/10.13039/501100011033 and by the European Union through“ERDF A way of making Europe.”。
文摘Purpose:To describe the characteristics of research outputs using persistent identifiers generated by ResearchGate to gain insight into what publications are shared and disseminated through this functionality,revealing their academic and non-academic impact.Design/methodology/approach:A total of 1,092,934 RG-DOIs were collected,using the DataCite API,along with bibliographic metadata for the associated registered output(RG-DOI publications).The subsequent analysis evaluated the publication date,document type,and language.These values were crossreferenced against the full text of a random sample of 666 records to verify accuracy.Findings:RG-DOIs have served primarily to identify and make accessible scholarly gray literature,including posters,presentations,conference papers,and theses,with notable emphasis on publications in Spanish and Portuguese.Around 41,000 citations from Web of Science indexed publications to RG publications are evidence of their infrequent but perceptible use in scholarly discourse.The declining number of registrations of RG-DOIs observed may indicate a shift in researcher preferences to alternative platforms for DOI generation.Research limitations:The study uncovered substantial inconsistencies in DataCite metadata,which can be attributed to the automated DOI registration process and internal changes in the available document types on ResearchGate.Practical implications:The study encountered challenges in conducting a quantitative analysis due to inconsistencies in the metadata.These have potential implications for researchers,practitioners,and librarians relying on RG-DOIs to conduct bibliometric or bibliographic analysis.Originality/value:This study is the first comprehensive analysis of RG-DOIs and,as such,provides a unique perspective into academic gray literature.It also sheds light on the quality of ResearchGate data transmitted to DataCite when registering DOIs.
