Albeit notable endeavors in the construction of organophosphorodithioates,the direct catalytic enantioselective synthesis of organophosphorodithioates still stands for a long-lasting challenge.Herein,an efficient orga...Albeit notable endeavors in the construction of organophosphorodithioates,the direct catalytic enantioselective synthesis of organophosphorodithioates still stands for a long-lasting challenge.Herein,an efficient organocatalytic enantioselective nucleophilic addition of vinylidene ortho-quinone methide with phosphinothioic thioanhydride as nucleophilic reagent has been achieved by the dual catalysis of cinchona alkaloid-derived squaramide and 4-dimethylaminopyridine.This protocol provides a straightforward approach for accessing a variety of axially chiral phosphorodithiolated styrenes in good yields(up to 98 %yield) with high stereoselectivities(up to 97 % ee and >99:1 E/Z).展开更多
Aerodynamic performances of axial compressors are significantly affected by variation of Reynolds number in aero-engines.In the design and analysis of compressors,previous correction methods for cascades and stages ha...Aerodynamic performances of axial compressors are significantly affected by variation of Reynolds number in aero-engines.In the design and analysis of compressors,previous correction methods for cascades and stages have difficulties in predicting comprehensively Reynolds number effects on airfoils,matching and characteristics curves.This study proposes Re-correction models for loss,deviation angle and endwall blockage based on classical theories and cascade tests,and loss and deviation models show good agreement in test data of NACA65 and C4 cascades.Throughflow method considering Reynolds number effects is developed by integrating the correction models into a verified Streamline Curvature(SLC)tool.A three-stage axial compressor is investigated through SLC and CFD methods from design Reynolds number(Red=2106)to low Re=4104,and the numerical methods are validated with test data of characteristic curves and spanwise distributions at Red.With Re reduction,SLC method with correction models well predicts variation in overall performances compared with CFD calculations and Wassell's model.Streamwise and spanwise matching such as total pressure and loss distributions in SLC predictions are basically consistent with those in CFD results at near-stall points under design and low Reynolds numbers.SLC and CFD methods share similar detections of stall risks in the third stage(Stg3),and their analyses of diffusion processes deviate to some extent due to different predictions in separated endwall flow.The correction models can be adopted to consider Reynolds number effects in through-flow design and analysis of axial compressors.展开更多
AIM:To evaluate the agreement of axial length(AL),anterior chamber parameters,and total cornea power obtained by swept-source optical coherence tomography(SS-OCT)-based and Scheimpflug-based optical biometers in myopi...AIM:To evaluate the agreement of axial length(AL),anterior chamber parameters,and total cornea power obtained by swept-source optical coherence tomography(SS-OCT)-based and Scheimpflug-based optical biometers in myopic children.METHODS:AL,steep keratometry(K),flat K,posterior corneal keratometry(PK),total keratometry(TK),anterior chamber depth(ACD),horizontal corneal diameter(CD),and central corneal thickness(CCT)were obtained using IOL Master 700 and Pentacam AXL.The agreement between the devices was evaluated using intraclass correlation coefficients(ICC),Bland-Altman plots,and astigmatism vector analysis.RESULTS:Totally 175 myopic children(48.5%male)with a mean age of 10.29±2.14y were enrolled.The ICC and Bland-Altman plots indicated a satisfactory agreement for AL,ACD,and CCT.The mean difference in CD of-0.31±0.30 mm was considered clinically significant(>0.2 mm).Additionally,measurements of K and TK obtained from the IOL Master 700 showed good agreement.Nevertheless,there were clinically significant differences observed in PK,simulated keratometry(simK),total cornea power,and astigmatism(at least 10%of the cases with a difference of>10 degrees in meridian)between the two devices.CONCLUSION:The study findings demonstrate a significant difference in K,PK,astigmatism,and CD,indicating that the two optical biometers cannot be considered interchangeable.Therefore,it is recommended to utilize one kind device for follow-up examinations in myopic children.展开更多
To enhance the deformation capacity of vertical support columns of underground structures and improve their overall seismic performance,a new truncated column connected by unbonded prestressed tendons is proposed,insp...To enhance the deformation capacity of vertical support columns of underground structures and improve their overall seismic performance,a new truncated column connected by unbonded prestressed tendons is proposed,inspired by the concepts of the toughness seismic resistance and rocking design.Although many experimental and numerical studies have focused on underground structures,research on the behavior of truncated columns remains limited.This paper develops threedimensional(3D)finite element(FE)models for various columns,including cast-in-place column(CIPC)and prestressed tendon truncated column(PTTC),to evaluate the effects of three parameters,including axial compression ratio(ACR),initial tendon stress,and the effect of hole diameter on mechanical performance—specifically deformation capacity,strength,residual deformation and gap width.The results indicate that the deformability and self-centering ability of the prestressed tendon truncated column is obviously superior to the cast-in-place column,but its strength was comparatively lower.The axial compression ratio has obvious effects on seismic performance,especially deformation and residual deformation,while initial tendon stress and hole diameter influence performance only in the case of a small axial compression ratio.This study systematically identifies the influence of various factors on seismic performance.Additionally,this study proposes a method to evaluate the self-centering capability of structures and establishes an empirical relationship between maximum recoverable deformation and the axial compression ratio.The developed numerical model can serve as a tool for future studies to predict the seismic responses of overall subway stations that feature truncated columns.展开更多
This study focused on the buckling characteristics of egg-shaped shells with single crack and double cracks under axial pressure.First,the geometric parameters of the egg-shaped shell were designed,and a numerical mod...This study focused on the buckling characteristics of egg-shaped shells with single crack and double cracks under axial pressure.First,the geometric parameters of the egg-shaped shell were designed,and a numerical model of the egg-shaped shell was established.Then,the initial crack was introduced into the equatorial weld of the egg-shaped shell,and the effects of the crack on the buckling characteristics under different wall thicknesses were explored,as were the effects of the single crack direction,double crack angle and spacing on the buckling characteristics.Finally,crack-free,single crack and double crack egg-shaped shells were fabricated from Q235 steel.The buckling loads and failure modes of the three egg-shaped shells were obtained via axial compression experiments.The numerical critical buckling loads and buckling modes were compared with the experimental results to verify the accuracy of the numerical model.The results of this study are valuable for the design of egg-shaped shells under axial loading.展开更多
With the continuous increase of aeroengine flight ceiling(>20 km),the thin atmosphere at high altitudes and the size effect all cause the compressor component inlet Reynolds number to decrease rapidly to a critical...With the continuous increase of aeroengine flight ceiling(>20 km),the thin atmosphere at high altitudes and the size effect all cause the compressor component inlet Reynolds number to decrease rapidly to a critical value(approximately 2.0×10^(5)),and the significant transition process on the blade/endwall surface leads to the sharp degradation of compressor performance,which seriously affects the engine fuel consumption and working stability at high altitudes.In this paper,the research progress on the internal flow mechanism and flow control methods of axial compressors at low Reynolds numbers is reviewed from the aspects of quantification and prediction of performance variation,flow loss mechanism related to separation and transition,efficient transition control and flow field organization.The development trend of the low-Reynolds-number effect of axial flow compressors is noted,and the difficulties and application prospects of aerodynamic design and efficient flow control methods for compressors under low Reynolds numbers at high altitudes are discussed.展开更多
Research on the mechanical–electrical properties is crucial for designing and preparing high-temperature superconducting(HTS)cables.Various winding core structures can influence the mechanical–electrical behavior of...Research on the mechanical–electrical properties is crucial for designing and preparing high-temperature superconducting(HTS)cables.Various winding core structures can influence the mechanical–electrical behavior of cables,but the impact of alterations in the winding core structure on the mechanical–electrical behavior of superconducting cables remains unclear.This paper presents a 3D finite element model to predict the performance of three cables with different core structures when subjected to transverse compression and axial tension.The three cables analyzed are CORC(conductor-on-round-core),CORT(conductor-on-round-tube),and HFRC(conductor-on-spiral-tube).A parametric analysis is carried out by varying the core diameter and inner-to-outer diameter ratio.Results indicate that the CORT cable demonstrates better performance in transverse compression compared to the CORC cable,aligning with experimental data.Among the three cables,the HFRC cables exhibit the weakest resistance to transverse deformation.However,the HFRC cable demonstrates superior tensile deformation resistance compared to the CORT cable,provided that the transverse compression properties are maintained.Finite element results also show that the optimum inner-to-outer diameter ratios for achieving the best transverse compression performance are approximately 0.8 for CORT cables and 0.6 for HFRC cables.Meanwhile,the study explores the effect of structural changes in HTS cable winding cores on their electromagnetic properties.It recommends utilizing small tape gaps,lower frequencies,and spiral core construction to minimize eddy losses.The findings presented in this paper offer valuable insights for the commercialization and practical manufacturing of HTS cables.展开更多
Effective motors are crucial for driving astronomical telescopes,especially for those operating in Antarctica,where the harsh environment and operating conditions,including extreme low temperature,ice/snow accumulatio...Effective motors are crucial for driving astronomical telescopes,especially for those operating in Antarctica,where the harsh environment and operating conditions,including extreme low temperature,ice/snow accumulation,low power consumption,and unattended operation,introduce challenges to the design and development of motor drives.We present the design of a permanent magnet synchronous motor suitable for this environment,conducting a quantitative analysis on the impacts of cryogenic conditions on lubricant performance,differential thermal contraction of metallic components,and remanent flux density of neodymium iron boron(N52)permanent magnets.We also implement a labyrinth seal structure,combined with silicone sealing rings,to mitigate ice crystal intrusion risks.Finite element analysis and laboratory tests demonstrate a maximum torque output of 25 Nm.This kind of motor is used in the Antarctic 15 cm Near Infrared Telescope at Dome A,Antarctica.Operation data shows a total encoder feedback error of 0.0678"for the telescope control system with 15"s^(−1)tracking speed at−56.79°C.These results comprehensively validate the high reliability and precision of the motor under the extreme conditions of the polar environment.展开更多
Atropisomeric phosphines are crucial for asymmetric catalysis but remain synthetically challenging.Herein,an N-heterocyclic carbene(NHC)catalyzed esterification reaction of dialdehydes with arylboronic acids was devel...Atropisomeric phosphines are crucial for asymmetric catalysis but remain synthetically challenging.Herein,an N-heterocyclic carbene(NHC)catalyzed esterification reaction of dialdehydes with arylboronic acids was developed,successfully constructing the framework of axially chiral phosphorus compounds.Mechanistic studies have revealed that the reaction initially undergoes a desymmetrization process,followed by a kinetic resolution pathway,affording a series of axially chiral phosphorus compounds with high enantioselectivity(up to 92%ee).展开更多
Objective:To investigate the influence of axial length(AL),corneal curvature(CR),and the ratio of axial length to corneal radius of curvature(AL/CR)on myopia in children,and to evaluate the accuracy and specificity of...Objective:To investigate the influence of axial length(AL),corneal curvature(CR),and the ratio of axial length to corneal radius of curvature(AL/CR)on myopia in children,and to evaluate the accuracy and specificity of AL/CR in diagnosing myopia in children.Methods:A cross-sectional study was conducted.A total of 200 children(400 eyes)aged 6-12 years were recruited from the ophthalmology outpatient clinic of Fuling District People’s Hospital from December 2022 to December 2023.AL,CR,and AL/CR were measured,and comprehensive optometry was performed under cycloplegia,with the results recorded in spherical equivalent(SE)form.Results:A total of 200 subjects(400 eyes)were included in this study,of which 330 eyes(82.50%)were myopic.No significant differences in CR were observed among different refractive groups,while significant differences were noted in SE,AL,and AL/CR.The AL and AL/CR ratios were higher in myopic eyes compared to emmetropic and hyperopic eyes.Using cycloplegia as the gold standard,SE in the myopia group was correlated with AL,AL/CR,and CR,with stronger correlations observed with AL and AL/CR.An AL/CR value>3 demonstrated a sensitivity of 0.918,specificity of 0.786,misdiagnosis rate of 0.214,missed diagnosis rate of 0.082,and accuracy of 89.5%in diagnosing myopia.Conclusion:AL and AL/CR values are highly correlated with SE,with the strongest correlation observed in the myopia group.The AL/CR value exhibits high diagnostic value in determining myopia in children.展开更多
Steel cylindrical shells are widely used in engineering structures due to their high strength-to-weight ratio,but they are vulnerable to buckling under axial loads.To address this limitation,fiber-reinforced polymer(F...Steel cylindrical shells are widely used in engineering structures due to their high strength-to-weight ratio,but they are vulnerable to buckling under axial loads.To address this limitation,fiber-reinforced polymer(FRP)composites have emerged as promising materials for structural reinforcement.This study investigates the buckling behavior of steel cylindrical shells reinforced with inner and outer layers of polymer composite materials under axial compression.Using analytical and numerical modeling methods,the critical buckling loads for different reinforcement options were evaluated.Two-sided glass fiber reinforced plastic(GFRP)or carbon fiber reinforced plastic(CFRP)coatings,as well as combined coatings with layers of different composites,were considered.GFRP+CFRPIn the calculations,the coatings were treated as homogeneous orthotropic materials with equivalent averaged elastic characteristics.The numerical analysis revealed that CFRP reinforcement achieved the highest increase in buckling load,with improvements ranging from 9.84%to 47.29%,depending on the composite thickness and steel shell thickness.GFRP reinforcement,while beneficial,demonstrated a lower effectiveness,with buckling load increases between 5.89%and 19.30%.The hybrid reinforcement provided an optimal balance,improving buckling resistance by GFRP+CFRP6.94%to 43.95%.Statistical analysis further identified composite type and thickness as the most significant factors affecting buckling performance.The findings suggest that CFRP is the preferred reinforcement material,especially when applied to thin-walled cylindrical shells,while hybrid reinforcements can be effectively utilized for structures requiring a balance between stiffness and ductility.These insights provide a foundation for optimizing FRP reinforcement strategies to enhance the structural integrity of steel shells in engineering applications.展开更多
AIM:To evaluate the effects of microlens design of peripheral defocus modifying spectacle lenses(PDMSLs)and non-microlens design of PDMSLs on controlling myopia progression in children and adolescents.METHODS:A system...AIM:To evaluate the effects of microlens design of peripheral defocus modifying spectacle lenses(PDMSLs)and non-microlens design of PDMSLs on controlling myopia progression in children and adolescents.METHODS:A systematic search was carried out in the PubMed,Cochrane Library,Embase,CNKI,and Web of Science databases.The search targeted randomized controlled trials(RCTs)and cohort studies(CTs)that explored the effects of PDMSLs on myopia control among children and adolescents.The Cochrane risk-of-bias tool and the Newcastle-Ottawa Scale were employed to evaluate the risk of bias in the included studies.The published biases of the included studies were evaluated using Egger’s test.RESULTS:Nine studies(7 RCTs,2 CTs)were included,involving 4332 participants in the PDMSLs group and 7317 participants in the single vision lenses(SVLs)group.Metaanalysis showed that PDMSLs with microlens design had lower change in spherical equivalent refraction(SER)than SVLs at 6,12,18,and 24mo after wearing glasses,with reductions of 0.19 D(95%CI:0.14 to 0.24,P<0.00001),0.36 D(95%CI:0.25 to 0.46,P<0.00001),0.43 D(95%CI:0.32 to 0.55,P<0.00001),and 0.51 D(95%CI:0.33 to 0.69,P<0.00001),respectively.The changes in axial length(AL)were also lower in PDMSLs compared to SVLs,with reductions of-0.09 mm(95%CI:-0.13 to-0.04,P=0.0002),-0.15 mm(95%CI:-0.21 to-0.08,P<0.00001),-0.27 mm(95%CI:-0.34 to-0.20,P<0.00001),and-0.29 mm(95%CI:-0.38 to-0.20,P<0.00001),respectively.There was no significant difference between the non-microlens group and SVLs in controlling the changes of SER and AL in myopia(both P>0.05).CONCLUSION:The synthesized evidence indicates superior myopia management outcomes with microlens design of PDMSLs compared to both SVLs and nonmicrolens design of PDMSLs in children and adolescents.展开更多
In recent years,cold-formed steel(CFS)built-up sections have gained a lot of attention in construction.This is mainly because of their structural efficiency and the design advantages they offer.They provide better loa...In recent years,cold-formed steel(CFS)built-up sections have gained a lot of attention in construction.This is mainly because of their structural efficiency and the design advantages they offer.They provide better loadbearing strength and show greater resistance to elastic instability.This study looks at both experimental and numerical analysis of built-up CFS columns.The columns were formed by joining two C-sections in different ways:back-to-back,face-to-face,and box arrangements.Each type was tested with different slenderness ratios.For the experiments,the back-to-back and box sections were connected using two rows of rivets.The face-to-face sections,on the other hand,were joined by welding.In order to improve axial strength and overall stability,all column samples were filled with ordinary concrete,conforming to class C25/30.The numerical modeling was done in ABAQUS to study themechanical behavior of the columns.This helped in understanding how different joining methods affect their axial compression performance.Analytical checkswere also carried out using Eurocode 3 for hollowsections and Eurocode 4 for concretefilled sections.The role of concrete confinement was examined as well,following American Concrete Institute(ACI)guidelines,for both face-to-face and box-shaped columns.Thenumerical results matched closely with the experimental findings,with variations of less than 5%.The study identified key failure modes such as local buckling and distortional buckling.It highlighted how section shape,type of connection,and concrete infill all play amajor role in improving the strength of built-up CFS columns.展开更多
Moist-electric generation,a green and environmentally friendly energy harvesting technology,is undoubt-edly one of the effective methods to alleviate energy shortages and environmental damage.However,the lack of fiber...Moist-electric generation,a green and environmentally friendly energy harvesting technology,is undoubt-edly one of the effective methods to alleviate energy shortages and environmental damage.However,the lack of fiber-like moist-electric generators(MEGs)that combine continuous power generation and high electrical output performance has constrained the development of moist-electric in the fields of flexi-ble wearable and self-power supplies.In this work,sodium alginate(SA)/multi-walled carbon nanotubes(MWCNT)fibers with axial heterogeneous(axi-he)of oxygen-containing functional groups(Ocfgs)are prepared through a mold forming method in assistance with the coagulation process.The interaction be-tween axi-he MEG and moisture is investigated by analyzing the electrical signal changes of dried MEG under moisture stimulation.The maximum output voltage and current of axi-he MEG can reach 0.35 V and 1.92μA under the stimulation of moisture.Based on the regulation of Ocfgs,axi-he MEG has a con-tinuous high moist-electric performance and environmental adaptability.The maximum output power density(Pmo)of axi-he MEG with a length of only 2 cm can reach 27.37μW cm-2 at RH=90%,which exceeds most of the MEGs reported in literature.Meanwhile,a continuous output voltage of 0.33-0.37 V for more than 15 h can be obtained from this axi-he MEG.Thus,the axi-he MEG from Ocfg distribution design and mold forming method provides a new way of clean energy generation using moisture from the ambient environment,exhibiting enormous potential in energy supply for Internet of Things(IoT)devices.展开更多
Strong multi-kilotesla magnetic fields have various applications in high-energy density science and laboratory astrophysics, but they are not readily available. In our previous work [Y. Shi et al., Phys. Rev. Lett. 13...Strong multi-kilotesla magnetic fields have various applications in high-energy density science and laboratory astrophysics, but they are not readily available. In our previous work [Y. Shi et al., Phys. Rev. Lett. 130, 155101(2023)], we developed a novel approach for generating such fields using multiple conventional laser beams with a twist in the pointing direction. This method is particularly well-suited for multi-kilojoule petawatt-class laser systems like SG-Ⅱ UP, which are designed with multiple linearly polarized beamlets. Utilizing three-dimensional kinetic particle-in-cell simulations, we examine critical factors for a proof-of-principle experiment, such as laser polarization, relative pulse delay,phase offset, pointing stability, and target configuration, and their impact on magnetic field generation. Our general conclusion is that the approach is very robust and can be realized under a wide range of laser parameters and plasma conditions. We also provide an in-depth analysis of the axial magnetic field configuration, azimuthal electron current, and electron and ion orbital angular momentum densities.Supported by a simple model, our analysis shows that the axial magnetic field decays owing to the expansion of hot electrons.展开更多
The increasing performance demands of modern aero engines necessitate the integrated design of compressor transition ducts with upstream components to reduce the axial length of the engine.However,this design approach...The increasing performance demands of modern aero engines necessitate the integrated design of compressor transition ducts with upstream components to reduce the axial length of the engine.However,this design approach narrows the spacing between the stator and the strut,making traditional research on transition ducts only with struts unsuitable.The numerical results and experimental oil flow visualization results were utilized to reconstruct the three-dimensional flow structures in the stator passages under various operating conditions.Additionally,numerical methods were employed to analyze the mechanisms of the strut's effect on the upstream stator in an aggressive transition duct.The results show that the strut potential field increases the load on the upstream stator,leading to severe blade surface separation and corner separation/stall,and redistributes the inflow angle of the upstream stators circumferentially,resulting in significant differences in the flow structures within the stator passages on both sides.The separation flows within the stator passages mainly manifest in five types:pressure surface separation vortex,suction surface concentrated shedding vortex,suction surface separation vortex,suction surface-corner stall separation vortex,and suction surface separation vortex pair.Under different operating conditions,the separation flows within the stator passages are always composed of a part of these five types or a transitional state between two of them.展开更多
AIM:To evaluate the efficacy of the Tecnis Symfony ZXR00 lens in achieving optimal visual outcomes for cataract surgery patients with axial length(AL)shorter than 24 mm.METHODS:A total of 21 subjects(37 eyes)were subm...AIM:To evaluate the efficacy of the Tecnis Symfony ZXR00 lens in achieving optimal visual outcomes for cataract surgery patients with axial length(AL)shorter than 24 mm.METHODS:A total of 21 subjects(37 eyes)were submitted to cataract surgery and implantation of Tecnis Symfony ZXR00 lens(Johnson&Johnson Vision)was assessed.Patients were examined at 5 m,80 cm,and 40 cm for uncorrected distance visual acuity(UCDVA)and corrected distance visual acuity(CDVA),uncorrected intermediate(UCIVA),and uncorrected near visual acuity(UCNVA).Further,based on the optimal distance correction,the monocular defocusing curve in the range of+0.5 to-3.5 D was investigated.A simple patient-reported spectacle independence questionnaire(PRSIQ)was used to evaluate subjects’subjective feelings about their dependence on glasses at various distances.Multiple linear regression was employed to examine the association amony intraocular lenses(IOLs)diopter,AL,corneal curvature,anterior chamber depth,mean manifest refractive spherical equivalent,pupil,pupil/scan,target refraction,and near vision(logMAR).RESULTS:The study demonstrated enhanced UCNVA alongside comparable distant vision and UCIVA outcomes in eyes with AL shorter than 24 mm.Mean post-operative UCDVA significantly improved from preoperative levels 0.530±0.406(P=0.000).Notably,83.3%of eyes achieved 0.01 logMAR in UCNVA.Five unilateral cases with blended IOL implantation also showed satisfactory visual acuity and satisfaction.The 90.5%(19/21)achieved spectacle independence.The average score for self-reported spectacle-independence on the PRSIQ was 3.52 with a standard deviation of 0.98.The results of the regression analysis revealed that one predictor,the pupil/scan accounted for 27.6%of the variation in near vision[logMAR;F(1,35)=13.33,P<0.01].CONCLUSION:The results affirm the effectiveness of the Tecnis Symfony ZXR00 lens in enhancing visual outcomes for cataract surgery patients with AL shorter than 24 mm.Additionally,the pupil/scan emerges as a critical factor influencing postoperative near vision.展开更多
A new phenomenological model(axionic QCD string)is constructed to study the topological issues of the QCD vacuum and hadron structure.It provides an alternative way of tackling the Strong CP problem,which is different...A new phenomenological model(axionic QCD string)is constructed to study the topological issues of the QCD vacuum and hadron structure.It provides an alternative way of tackling the Strong CP problem,which is different from the traditional Peccei–Quinn approach.Neither new particle nor extra symmetry is introduced,and the role of the Peccei–Quinn axion is played by a quasiparticle arising from the phase of the quark condensate,dubbed as axionic excitation.The derivative of this excitation field is decomposed into a regular part and a singular part,and the latter contains vorticity from the string configuration.A hidden gauge symmetry is revealed in this decomposition and vorticity is represented by an emergent gauge field associated with anomalies.These components,together with the anomaly-inflow mechanism,complete the effective Lagrangian description for the axionic QCD string.展开更多
The effects of Reynolds number on the compressor efficiency are investigated by tests on three highlyloaded 10-stage axial compressors.The tests are conducted by adjusting the inlet total pressure,and thus different R...The effects of Reynolds number on the compressor efficiency are investigated by tests on three highlyloaded 10-stage axial compressors.The tests are conducted by adjusting the inlet total pressure,and thus different Reynolds numbers are obtained.The results indicate that the compressor efficiency decreases when the Reynolds number decreases.Based on the test results,reasonable correlations between the Reynolds number and compressor efficiency for each of the three compressors are obtained.The comparison between the test result-deduced correlations and Wassell correlations indicates that the effects of Reynolds number on the efficiency predicted by the Wassell correlations are less than those obtained by the test result-deduced correlations.Owing to the complex loss models and flow behavior in highly-loaded multi-stage compressors,additional influence factors,including the tip clearance and the compressor inlet duct design,should be considered for performance correlations.Nevertheless,the Wassell correlations are valid for the tendency prediction of performance changes relating to the Reynolds number,while accurate correlations still largely depend on the specific test results.展开更多
The efficiency of energy conversion from mechanical to electrical in AC generators is not entirely optimal,as power losses are converted into heat.Accurate thermal modeling and temperature measurement of advanced elec...The efficiency of energy conversion from mechanical to electrical in AC generators is not entirely optimal,as power losses are converted into heat.Accurate thermal modeling and temperature measurement of advanced electric machines with complex structures are mandatory to confirm their reliability and safe operation.In a unique axial transverse flux switching permanent magnet(ATFSPM)generator,due to its high power density,large stray loss from leakage flux,compact topology,and totally enclosed structure,thermal analysis is of paramount significance.In this paper,thermal modeling and analysis of ATFSPM are carried out in detail using a three-dimensional(3D)finite element analysis(FEA)to evaluate the thermal condition for a precise performance improvement.To begin,all loss sources are accurately derived using 3-D FEA and analytical methods,taking into account the temperature dependence of material properties,and then losses are coupled to the thermal model as heat sources.Afterward,aiming for realistic thermal modelling,the convection heat transfer in the different regions of internal and external areas as well as thin layers of interface gaps between components are all considered.In addition,the prototype of ATFSPM is supplied to validate the accuracy of 3-D FEA temperature prediction.Furthermore,a novel technique is carried out to effectively improve thermal performance,enhance the efficiency,and limit hot-spot temperatures.The steady-state and transient temperature results demonstrate the high accuracy of the thermal modeling,enhance the secure operation of the ATFSPM,and facilitate increased loading utilizing the proposed technique.(1)展开更多
基金financial support from Natural Science Foundation of China (No.22161005)Guangxi Natural Science Foundation (Nos.2021GXNSFDA075005,2024GXNSFFA010001)。
文摘Albeit notable endeavors in the construction of organophosphorodithioates,the direct catalytic enantioselective synthesis of organophosphorodithioates still stands for a long-lasting challenge.Herein,an efficient organocatalytic enantioselective nucleophilic addition of vinylidene ortho-quinone methide with phosphinothioic thioanhydride as nucleophilic reagent has been achieved by the dual catalysis of cinchona alkaloid-derived squaramide and 4-dimethylaminopyridine.This protocol provides a straightforward approach for accessing a variety of axially chiral phosphorodithiolated styrenes in good yields(up to 98 %yield) with high stereoselectivities(up to 97 % ee and >99:1 E/Z).
基金supported by the National Science and Tech-nology Major Project of China(Nos.2017-II-0007-0021 and J2019-II-0017-0038)。
文摘Aerodynamic performances of axial compressors are significantly affected by variation of Reynolds number in aero-engines.In the design and analysis of compressors,previous correction methods for cascades and stages have difficulties in predicting comprehensively Reynolds number effects on airfoils,matching and characteristics curves.This study proposes Re-correction models for loss,deviation angle and endwall blockage based on classical theories and cascade tests,and loss and deviation models show good agreement in test data of NACA65 and C4 cascades.Throughflow method considering Reynolds number effects is developed by integrating the correction models into a verified Streamline Curvature(SLC)tool.A three-stage axial compressor is investigated through SLC and CFD methods from design Reynolds number(Red=2106)to low Re=4104,and the numerical methods are validated with test data of characteristic curves and spanwise distributions at Red.With Re reduction,SLC method with correction models well predicts variation in overall performances compared with CFD calculations and Wassell's model.Streamwise and spanwise matching such as total pressure and loss distributions in SLC predictions are basically consistent with those in CFD results at near-stall points under design and low Reynolds numbers.SLC and CFD methods share similar detections of stall risks in the third stage(Stg3),and their analyses of diffusion processes deviate to some extent due to different predictions in separated endwall flow.The correction models can be adopted to consider Reynolds number effects in through-flow design and analysis of axial compressors.
基金Supported by National Natural Science Foundation of Guangdong,China(No.2020A1515010829,No.2023A1515011652,No.2025A1515012389)Science and Technology Program of Guangzhou,China(No.2025A03J4033).
文摘AIM:To evaluate the agreement of axial length(AL),anterior chamber parameters,and total cornea power obtained by swept-source optical coherence tomography(SS-OCT)-based and Scheimpflug-based optical biometers in myopic children.METHODS:AL,steep keratometry(K),flat K,posterior corneal keratometry(PK),total keratometry(TK),anterior chamber depth(ACD),horizontal corneal diameter(CD),and central corneal thickness(CCT)were obtained using IOL Master 700 and Pentacam AXL.The agreement between the devices was evaluated using intraclass correlation coefficients(ICC),Bland-Altman plots,and astigmatism vector analysis.RESULTS:Totally 175 myopic children(48.5%male)with a mean age of 10.29±2.14y were enrolled.The ICC and Bland-Altman plots indicated a satisfactory agreement for AL,ACD,and CCT.The mean difference in CD of-0.31±0.30 mm was considered clinically significant(>0.2 mm).Additionally,measurements of K and TK obtained from the IOL Master 700 showed good agreement.Nevertheless,there were clinically significant differences observed in PK,simulated keratometry(simK),total cornea power,and astigmatism(at least 10%of the cases with a difference of>10 degrees in meridian)between the two devices.CONCLUSION:The study findings demonstrate a significant difference in K,PK,astigmatism,and CD,indicating that the two optical biometers cannot be considered interchangeable.Therefore,it is recommended to utilize one kind device for follow-up examinations in myopic children.
基金National Natural Science Foundation of China under Grant Nos.52478488 and 51908013the National Key Basic Research and Development Program of China under Grant No.2018YFC1504305。
文摘To enhance the deformation capacity of vertical support columns of underground structures and improve their overall seismic performance,a new truncated column connected by unbonded prestressed tendons is proposed,inspired by the concepts of the toughness seismic resistance and rocking design.Although many experimental and numerical studies have focused on underground structures,research on the behavior of truncated columns remains limited.This paper develops threedimensional(3D)finite element(FE)models for various columns,including cast-in-place column(CIPC)and prestressed tendon truncated column(PTTC),to evaluate the effects of three parameters,including axial compression ratio(ACR),initial tendon stress,and the effect of hole diameter on mechanical performance—specifically deformation capacity,strength,residual deformation and gap width.The results indicate that the deformability and self-centering ability of the prestressed tendon truncated column is obviously superior to the cast-in-place column,but its strength was comparatively lower.The axial compression ratio has obvious effects on seismic performance,especially deformation and residual deformation,while initial tendon stress and hole diameter influence performance only in the case of a small axial compression ratio.This study systematically identifies the influence of various factors on seismic performance.Additionally,this study proposes a method to evaluate the self-centering capability of structures and establishes an empirical relationship between maximum recoverable deformation and the axial compression ratio.The developed numerical model can serve as a tool for future studies to predict the seismic responses of overall subway stations that feature truncated columns.
基金supported by the National Natural Science Foundation of China(Grant No.52271277)the Natural Science Foundation of Jiangsu Province(Grant No.BK20211343)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.SJCX23_2150).
文摘This study focused on the buckling characteristics of egg-shaped shells with single crack and double cracks under axial pressure.First,the geometric parameters of the egg-shaped shell were designed,and a numerical model of the egg-shaped shell was established.Then,the initial crack was introduced into the equatorial weld of the egg-shaped shell,and the effects of the crack on the buckling characteristics under different wall thicknesses were explored,as were the effects of the single crack direction,double crack angle and spacing on the buckling characteristics.Finally,crack-free,single crack and double crack egg-shaped shells were fabricated from Q235 steel.The buckling loads and failure modes of the three egg-shaped shells were obtained via axial compression experiments.The numerical critical buckling loads and buckling modes were compared with the experimental results to verify the accuracy of the numerical model.The results of this study are valuable for the design of egg-shaped shells under axial loading.
基金co-supported by the National Natural Science Foundation of China(No.52306053)the Science Center for Gas Turbine Project,China(No.P2022-B-Ⅱ-005-001)the National Science and Technology Major Project of China(No.2017-Ⅱ-0010-0024)。
文摘With the continuous increase of aeroengine flight ceiling(>20 km),the thin atmosphere at high altitudes and the size effect all cause the compressor component inlet Reynolds number to decrease rapidly to a critical value(approximately 2.0×10^(5)),and the significant transition process on the blade/endwall surface leads to the sharp degradation of compressor performance,which seriously affects the engine fuel consumption and working stability at high altitudes.In this paper,the research progress on the internal flow mechanism and flow control methods of axial compressors at low Reynolds numbers is reviewed from the aspects of quantification and prediction of performance variation,flow loss mechanism related to separation and transition,efficient transition control and flow field organization.The development trend of the low-Reynolds-number effect of axial flow compressors is noted,and the difficulties and application prospects of aerodynamic design and efficient flow control methods for compressors under low Reynolds numbers at high altitudes are discussed.
基金supported by the National Natural Science Foundation of China(12072136).
文摘Research on the mechanical–electrical properties is crucial for designing and preparing high-temperature superconducting(HTS)cables.Various winding core structures can influence the mechanical–electrical behavior of cables,but the impact of alterations in the winding core structure on the mechanical–electrical behavior of superconducting cables remains unclear.This paper presents a 3D finite element model to predict the performance of three cables with different core structures when subjected to transverse compression and axial tension.The three cables analyzed are CORC(conductor-on-round-core),CORT(conductor-on-round-tube),and HFRC(conductor-on-spiral-tube).A parametric analysis is carried out by varying the core diameter and inner-to-outer diameter ratio.Results indicate that the CORT cable demonstrates better performance in transverse compression compared to the CORC cable,aligning with experimental data.Among the three cables,the HFRC cables exhibit the weakest resistance to transverse deformation.However,the HFRC cable demonstrates superior tensile deformation resistance compared to the CORT cable,provided that the transverse compression properties are maintained.Finite element results also show that the optimum inner-to-outer diameter ratios for achieving the best transverse compression performance are approximately 0.8 for CORT cables and 0.6 for HFRC cables.Meanwhile,the study explores the effect of structural changes in HTS cable winding cores on their electromagnetic properties.It recommends utilizing small tape gaps,lower frequencies,and spiral core construction to minimize eddy losses.The findings presented in this paper offer valuable insights for the commercialization and practical manufacturing of HTS cables.
基金supported by the Space Debris Resear-ch Project,China(KJSP2020010102)the NationalKey R&D Program of China(2022YFC2807300).
文摘Effective motors are crucial for driving astronomical telescopes,especially for those operating in Antarctica,where the harsh environment and operating conditions,including extreme low temperature,ice/snow accumulation,low power consumption,and unattended operation,introduce challenges to the design and development of motor drives.We present the design of a permanent magnet synchronous motor suitable for this environment,conducting a quantitative analysis on the impacts of cryogenic conditions on lubricant performance,differential thermal contraction of metallic components,and remanent flux density of neodymium iron boron(N52)permanent magnets.We also implement a labyrinth seal structure,combined with silicone sealing rings,to mitigate ice crystal intrusion risks.Finite element analysis and laboratory tests demonstrate a maximum torque output of 25 Nm.This kind of motor is used in the Antarctic 15 cm Near Infrared Telescope at Dome A,Antarctica.Operation data shows a total encoder feedback error of 0.0678"for the telescope control system with 15"s^(−1)tracking speed at−56.79°C.These results comprehensively validate the high reliability and precision of the motor under the extreme conditions of the polar environment.
基金Project supported by the Natural Science Foundation of Henan Province(Nos.232300421234,252300421726)the Leading Talents in Scientific and Technological Innovation in Shangqiu(No.SQRC202212004)the Program of Ecological Environmental Protection in the Area of Old Course of Yellow River of Shangqiu Normal University。
文摘Atropisomeric phosphines are crucial for asymmetric catalysis but remain synthetically challenging.Herein,an N-heterocyclic carbene(NHC)catalyzed esterification reaction of dialdehydes with arylboronic acids was developed,successfully constructing the framework of axially chiral phosphorus compounds.Mechanistic studies have revealed that the reaction initially undergoes a desymmetrization process,followed by a kinetic resolution pathway,affording a series of axially chiral phosphorus compounds with high enantioselectivity(up to 92%ee).
基金Chongqing Fuling District Science and Health Joint Medical Research Project(2022KWLH069)。
文摘Objective:To investigate the influence of axial length(AL),corneal curvature(CR),and the ratio of axial length to corneal radius of curvature(AL/CR)on myopia in children,and to evaluate the accuracy and specificity of AL/CR in diagnosing myopia in children.Methods:A cross-sectional study was conducted.A total of 200 children(400 eyes)aged 6-12 years were recruited from the ophthalmology outpatient clinic of Fuling District People’s Hospital from December 2022 to December 2023.AL,CR,and AL/CR were measured,and comprehensive optometry was performed under cycloplegia,with the results recorded in spherical equivalent(SE)form.Results:A total of 200 subjects(400 eyes)were included in this study,of which 330 eyes(82.50%)were myopic.No significant differences in CR were observed among different refractive groups,while significant differences were noted in SE,AL,and AL/CR.The AL and AL/CR ratios were higher in myopic eyes compared to emmetropic and hyperopic eyes.Using cycloplegia as the gold standard,SE in the myopia group was correlated with AL,AL/CR,and CR,with stronger correlations observed with AL and AL/CR.An AL/CR value>3 demonstrated a sensitivity of 0.918,specificity of 0.786,misdiagnosis rate of 0.214,missed diagnosis rate of 0.082,and accuracy of 89.5%in diagnosing myopia.Conclusion:AL and AL/CR values are highly correlated with SE,with the strongest correlation observed in the myopia group.The AL/CR value exhibits high diagnostic value in determining myopia in children.
文摘Steel cylindrical shells are widely used in engineering structures due to their high strength-to-weight ratio,but they are vulnerable to buckling under axial loads.To address this limitation,fiber-reinforced polymer(FRP)composites have emerged as promising materials for structural reinforcement.This study investigates the buckling behavior of steel cylindrical shells reinforced with inner and outer layers of polymer composite materials under axial compression.Using analytical and numerical modeling methods,the critical buckling loads for different reinforcement options were evaluated.Two-sided glass fiber reinforced plastic(GFRP)or carbon fiber reinforced plastic(CFRP)coatings,as well as combined coatings with layers of different composites,were considered.GFRP+CFRPIn the calculations,the coatings were treated as homogeneous orthotropic materials with equivalent averaged elastic characteristics.The numerical analysis revealed that CFRP reinforcement achieved the highest increase in buckling load,with improvements ranging from 9.84%to 47.29%,depending on the composite thickness and steel shell thickness.GFRP reinforcement,while beneficial,demonstrated a lower effectiveness,with buckling load increases between 5.89%and 19.30%.The hybrid reinforcement provided an optimal balance,improving buckling resistance by GFRP+CFRP6.94%to 43.95%.Statistical analysis further identified composite type and thickness as the most significant factors affecting buckling performance.The findings suggest that CFRP is the preferred reinforcement material,especially when applied to thin-walled cylindrical shells,while hybrid reinforcements can be effectively utilized for structures requiring a balance between stiffness and ductility.These insights provide a foundation for optimizing FRP reinforcement strategies to enhance the structural integrity of steel shells in engineering applications.
基金Supported by Sichuan Province Science and Technology Plan(No.2023YFS0506)Medical Research Project of Jinniu District,Chengdu,Sichuan Province(No.JNKY2024-94)Xinglin Scholar Program at Chengdu University of Traditional Chinese Medicine(No.ZYTS2023028).
文摘AIM:To evaluate the effects of microlens design of peripheral defocus modifying spectacle lenses(PDMSLs)and non-microlens design of PDMSLs on controlling myopia progression in children and adolescents.METHODS:A systematic search was carried out in the PubMed,Cochrane Library,Embase,CNKI,and Web of Science databases.The search targeted randomized controlled trials(RCTs)and cohort studies(CTs)that explored the effects of PDMSLs on myopia control among children and adolescents.The Cochrane risk-of-bias tool and the Newcastle-Ottawa Scale were employed to evaluate the risk of bias in the included studies.The published biases of the included studies were evaluated using Egger’s test.RESULTS:Nine studies(7 RCTs,2 CTs)were included,involving 4332 participants in the PDMSLs group and 7317 participants in the single vision lenses(SVLs)group.Metaanalysis showed that PDMSLs with microlens design had lower change in spherical equivalent refraction(SER)than SVLs at 6,12,18,and 24mo after wearing glasses,with reductions of 0.19 D(95%CI:0.14 to 0.24,P<0.00001),0.36 D(95%CI:0.25 to 0.46,P<0.00001),0.43 D(95%CI:0.32 to 0.55,P<0.00001),and 0.51 D(95%CI:0.33 to 0.69,P<0.00001),respectively.The changes in axial length(AL)were also lower in PDMSLs compared to SVLs,with reductions of-0.09 mm(95%CI:-0.13 to-0.04,P=0.0002),-0.15 mm(95%CI:-0.21 to-0.08,P<0.00001),-0.27 mm(95%CI:-0.34 to-0.20,P<0.00001),and-0.29 mm(95%CI:-0.38 to-0.20,P<0.00001),respectively.There was no significant difference between the non-microlens group and SVLs in controlling the changes of SER and AL in myopia(both P>0.05).CONCLUSION:The synthesized evidence indicates superior myopia management outcomes with microlens design of PDMSLs compared to both SVLs and nonmicrolens design of PDMSLs in children and adolescents.
文摘In recent years,cold-formed steel(CFS)built-up sections have gained a lot of attention in construction.This is mainly because of their structural efficiency and the design advantages they offer.They provide better loadbearing strength and show greater resistance to elastic instability.This study looks at both experimental and numerical analysis of built-up CFS columns.The columns were formed by joining two C-sections in different ways:back-to-back,face-to-face,and box arrangements.Each type was tested with different slenderness ratios.For the experiments,the back-to-back and box sections were connected using two rows of rivets.The face-to-face sections,on the other hand,were joined by welding.In order to improve axial strength and overall stability,all column samples were filled with ordinary concrete,conforming to class C25/30.The numerical modeling was done in ABAQUS to study themechanical behavior of the columns.This helped in understanding how different joining methods affect their axial compression performance.Analytical checkswere also carried out using Eurocode 3 for hollowsections and Eurocode 4 for concretefilled sections.The role of concrete confinement was examined as well,following American Concrete Institute(ACI)guidelines,for both face-to-face and box-shaped columns.Thenumerical results matched closely with the experimental findings,with variations of less than 5%.The study identified key failure modes such as local buckling and distortional buckling.It highlighted how section shape,type of connection,and concrete infill all play amajor role in improving the strength of built-up CFS columns.
基金supported by the National Natural Science Foundation of China(No.22073015)the National Key R&D Program of China(No.2022YFB3704600).
文摘Moist-electric generation,a green and environmentally friendly energy harvesting technology,is undoubt-edly one of the effective methods to alleviate energy shortages and environmental damage.However,the lack of fiber-like moist-electric generators(MEGs)that combine continuous power generation and high electrical output performance has constrained the development of moist-electric in the fields of flexi-ble wearable and self-power supplies.In this work,sodium alginate(SA)/multi-walled carbon nanotubes(MWCNT)fibers with axial heterogeneous(axi-he)of oxygen-containing functional groups(Ocfgs)are prepared through a mold forming method in assistance with the coagulation process.The interaction be-tween axi-he MEG and moisture is investigated by analyzing the electrical signal changes of dried MEG under moisture stimulation.The maximum output voltage and current of axi-he MEG can reach 0.35 V and 1.92μA under the stimulation of moisture.Based on the regulation of Ocfgs,axi-he MEG has a con-tinuous high moist-electric performance and environmental adaptability.The maximum output power density(Pmo)of axi-he MEG with a length of only 2 cm can reach 27.37μW cm-2 at RH=90%,which exceeds most of the MEGs reported in literature.Meanwhile,a continuous output voltage of 0.33-0.37 V for more than 15 h can be obtained from this axi-he MEG.Thus,the axi-he MEG from Ocfg distribution design and mold forming method provides a new way of clean energy generation using moisture from the ambient environment,exhibiting enormous potential in energy supply for Internet of Things(IoT)devices.
基金support by the National Natural Science Foundation of China(Grant No.12322513)USTC Research Funds of the Double First-Class Initiative+1 种基金CAS Project for Young Scientists in Basic Research(Grant No.YSBR060)supported by the Office of Fusion Energy Sciences under Award No.DE-SC0023423。
文摘Strong multi-kilotesla magnetic fields have various applications in high-energy density science and laboratory astrophysics, but they are not readily available. In our previous work [Y. Shi et al., Phys. Rev. Lett. 130, 155101(2023)], we developed a novel approach for generating such fields using multiple conventional laser beams with a twist in the pointing direction. This method is particularly well-suited for multi-kilojoule petawatt-class laser systems like SG-Ⅱ UP, which are designed with multiple linearly polarized beamlets. Utilizing three-dimensional kinetic particle-in-cell simulations, we examine critical factors for a proof-of-principle experiment, such as laser polarization, relative pulse delay,phase offset, pointing stability, and target configuration, and their impact on magnetic field generation. Our general conclusion is that the approach is very robust and can be realized under a wide range of laser parameters and plasma conditions. We also provide an in-depth analysis of the axial magnetic field configuration, azimuthal electron current, and electron and ion orbital angular momentum densities.Supported by a simple model, our analysis shows that the axial magnetic field decays owing to the expansion of hot electrons.
基金supported by the National Natural Science Foundation of China(No.52276025)the Science Center for Gas Turbine Project of China(Nos.P2022-A-Ⅱ-001-001,P2022-A-Ⅱ-002-001 and P2022-B-Ⅱ-002-001)。
文摘The increasing performance demands of modern aero engines necessitate the integrated design of compressor transition ducts with upstream components to reduce the axial length of the engine.However,this design approach narrows the spacing between the stator and the strut,making traditional research on transition ducts only with struts unsuitable.The numerical results and experimental oil flow visualization results were utilized to reconstruct the three-dimensional flow structures in the stator passages under various operating conditions.Additionally,numerical methods were employed to analyze the mechanisms of the strut's effect on the upstream stator in an aggressive transition duct.The results show that the strut potential field increases the load on the upstream stator,leading to severe blade surface separation and corner separation/stall,and redistributes the inflow angle of the upstream stators circumferentially,resulting in significant differences in the flow structures within the stator passages on both sides.The separation flows within the stator passages mainly manifest in five types:pressure surface separation vortex,suction surface concentrated shedding vortex,suction surface separation vortex,suction surface-corner stall separation vortex,and suction surface separation vortex pair.Under different operating conditions,the separation flows within the stator passages are always composed of a part of these five types or a transitional state between two of them.
文摘AIM:To evaluate the efficacy of the Tecnis Symfony ZXR00 lens in achieving optimal visual outcomes for cataract surgery patients with axial length(AL)shorter than 24 mm.METHODS:A total of 21 subjects(37 eyes)were submitted to cataract surgery and implantation of Tecnis Symfony ZXR00 lens(Johnson&Johnson Vision)was assessed.Patients were examined at 5 m,80 cm,and 40 cm for uncorrected distance visual acuity(UCDVA)and corrected distance visual acuity(CDVA),uncorrected intermediate(UCIVA),and uncorrected near visual acuity(UCNVA).Further,based on the optimal distance correction,the monocular defocusing curve in the range of+0.5 to-3.5 D was investigated.A simple patient-reported spectacle independence questionnaire(PRSIQ)was used to evaluate subjects’subjective feelings about their dependence on glasses at various distances.Multiple linear regression was employed to examine the association amony intraocular lenses(IOLs)diopter,AL,corneal curvature,anterior chamber depth,mean manifest refractive spherical equivalent,pupil,pupil/scan,target refraction,and near vision(logMAR).RESULTS:The study demonstrated enhanced UCNVA alongside comparable distant vision and UCIVA outcomes in eyes with AL shorter than 24 mm.Mean post-operative UCDVA significantly improved from preoperative levels 0.530±0.406(P=0.000).Notably,83.3%of eyes achieved 0.01 logMAR in UCNVA.Five unilateral cases with blended IOL implantation also showed satisfactory visual acuity and satisfaction.The 90.5%(19/21)achieved spectacle independence.The average score for self-reported spectacle-independence on the PRSIQ was 3.52 with a standard deviation of 0.98.The results of the regression analysis revealed that one predictor,the pupil/scan accounted for 27.6%of the variation in near vision[logMAR;F(1,35)=13.33,P<0.01].CONCLUSION:The results affirm the effectiveness of the Tecnis Symfony ZXR00 lens in enhancing visual outcomes for cataract surgery patients with AL shorter than 24 mm.Additionally,the pupil/scan emerges as a critical factor influencing postoperative near vision.
基金supported by the Natural Science Foundation of Fujian Province(Grant No.2022J011130)the Research Starting Grant from Minjiang University(Grant No.30804317)。
文摘A new phenomenological model(axionic QCD string)is constructed to study the topological issues of the QCD vacuum and hadron structure.It provides an alternative way of tackling the Strong CP problem,which is different from the traditional Peccei–Quinn approach.Neither new particle nor extra symmetry is introduced,and the role of the Peccei–Quinn axion is played by a quasiparticle arising from the phase of the quark condensate,dubbed as axionic excitation.The derivative of this excitation field is decomposed into a regular part and a singular part,and the latter contains vorticity from the string configuration.A hidden gauge symmetry is revealed in this decomposition and vorticity is represented by an emergent gauge field associated with anomalies.These components,together with the anomaly-inflow mechanism,complete the effective Lagrangian description for the axionic QCD string.
文摘The effects of Reynolds number on the compressor efficiency are investigated by tests on three highlyloaded 10-stage axial compressors.The tests are conducted by adjusting the inlet total pressure,and thus different Reynolds numbers are obtained.The results indicate that the compressor efficiency decreases when the Reynolds number decreases.Based on the test results,reasonable correlations between the Reynolds number and compressor efficiency for each of the three compressors are obtained.The comparison between the test result-deduced correlations and Wassell correlations indicates that the effects of Reynolds number on the efficiency predicted by the Wassell correlations are less than those obtained by the test result-deduced correlations.Owing to the complex loss models and flow behavior in highly-loaded multi-stage compressors,additional influence factors,including the tip clearance and the compressor inlet duct design,should be considered for performance correlations.Nevertheless,the Wassell correlations are valid for the tendency prediction of performance changes relating to the Reynolds number,while accurate correlations still largely depend on the specific test results.
基金supported by research grants of the Iran National Science Foundation(INSF)under grant No.98002866。
文摘The efficiency of energy conversion from mechanical to electrical in AC generators is not entirely optimal,as power losses are converted into heat.Accurate thermal modeling and temperature measurement of advanced electric machines with complex structures are mandatory to confirm their reliability and safe operation.In a unique axial transverse flux switching permanent magnet(ATFSPM)generator,due to its high power density,large stray loss from leakage flux,compact topology,and totally enclosed structure,thermal analysis is of paramount significance.In this paper,thermal modeling and analysis of ATFSPM are carried out in detail using a three-dimensional(3D)finite element analysis(FEA)to evaluate the thermal condition for a precise performance improvement.To begin,all loss sources are accurately derived using 3-D FEA and analytical methods,taking into account the temperature dependence of material properties,and then losses are coupled to the thermal model as heat sources.Afterward,aiming for realistic thermal modelling,the convection heat transfer in the different regions of internal and external areas as well as thin layers of interface gaps between components are all considered.In addition,the prototype of ATFSPM is supplied to validate the accuracy of 3-D FEA temperature prediction.Furthermore,a novel technique is carried out to effectively improve thermal performance,enhance the efficiency,and limit hot-spot temperatures.The steady-state and transient temperature results demonstrate the high accuracy of the thermal modeling,enhance the secure operation of the ATFSPM,and facilitate increased loading utilizing the proposed technique.(1)
