Due to the bird’s eye view of remote sensing sensors,the orientational information of an object is a key factor that has to be considered in object detection.To obtain rotating bounding boxes,existing studies either ...Due to the bird’s eye view of remote sensing sensors,the orientational information of an object is a key factor that has to be considered in object detection.To obtain rotating bounding boxes,existing studies either rely on rotated anchoring schemes or adding complex rotating ROI transfer layers,leading to increased computational demand and reduced detection speeds.In this study,we propose a novel internal-external optimized convolutional neural network for arbitrary orientated object detection in optical remote sensing images.For the internal opti-mization,we designed an anchor-based single-shot head detector that adopts the concept of coarse-to-fine detection for two-stage object detection networks.The refined rotating anchors are generated from the coarse detection head module and fed into the refining detection head module with a link of an embedded deformable convolutional layer.For the external optimiza-tion,we propose an IOU balanced loss that addresses the regression challenges related to arbitrary orientated bounding boxes.Experimental results on the DOTA and HRSC2016 bench-mark datasets show that our proposed method outperforms selected methods.展开更多
Metal organic frameworks(MOFs)has broad application prospect in separation,catalysis,and adsorption.By a facile green method,we successfully fabricated prGO@cHKUST-1 composite membrane with the modification of dopamin...Metal organic frameworks(MOFs)has broad application prospect in separation,catalysis,and adsorption.By a facile green method,we successfully fabricated prGO@cHKUST-1 composite membrane with the modification of dopamine and orientated growth of MOFs.Mg/AI-layered double hydroxides(Mg/Al-LDHs)was used as a modulator to obtain cubic HKUST-1(cHKUST-1)with excellent morphology and special properties.Scanning Electron Microscopy(SEM),X-ray diffraction(XRD),and Fourier transform infrared spectroscopy(FTIR)etc.characte rization illustrated successful synthesis of cHKUST-1 and composite membranes.Cubic HKUST-1 can tune the inter-layer spacing of graphene oxide(GO)leading increase in hydrophilicity and flux of the membrane.Meanwhile,the reduction effect of PDA and intercalation effect of MOFs could change the stacked way of GO layers,forming several fuzzy pores and more active sites on membrane surface.The prGO@cHKUST-1 membrane has an excellent rejection for methylene blue(MB)(99.5%)and Congo red(CR)(71.2%).Moreover,the modified membra ne exhibited 10 and 5 times higher permeation flux than that of original GO membrane and prGO membrane,respectively.Thus,using orientated growth of MOFs to synthesize GO based composite membrane will provide useful insights in ultrahigh permeation flux membranes of dye and oil-water emulsion separation.展开更多
Hydrogenated amorphous silicon oxide(a-SiOx:H) is an attractive passivation material to suppress epitaxial growth and reduce the parasitic absorption loss in silicon heterojunction(SHJ) solar cells. In this paper, a-S...Hydrogenated amorphous silicon oxide(a-SiOx:H) is an attractive passivation material to suppress epitaxial growth and reduce the parasitic absorption loss in silicon heterojunction(SHJ) solar cells. In this paper, a-SiOx:H layers on different orientated c-Si substrates are fabricated. An optimal effective lifetime(τ(eff)) of 4743 μs and corresponding implied opencircuit voltage(iV(oc)) of 724 mV are obtained on〈100〉-orientated c-Si wafers. While τ(eff) of 2429 μs and iV_(oc) of 699 mV are achieved on 111-orientated substrate. The FTIR and XPS results indicate that the a-SiOx:H network consists of SiOx(Si-rich), Si–OH, Si–O–SiHx, SiO2 ≡ Si–Si, and O3 ≡ Si–Si. A passivation evolution mechanism is proposed to explain the different passivation results on different c-Si wafers. By modulating the a-SiOx:H layer, the planar silicon heterojunction solar cell can achieve an efficiency of 18.15%.展开更多
The effect that the market orientation brings to product innovation performance is reported and the degree of product innovativeness is explored. The interdepartmental integration inside the company is also investigat...The effect that the market orientation brings to product innovation performance is reported and the degree of product innovativeness is explored. The interdepartmental integration inside the company is also investigated. A series of hypotheses were developed aiming at presenting a conceptual framework to clarify how market orientation contributes to product innovation performance-moderated by the degree of product innovativeness and affected by the interdepartmental integration. Survey data from 36 business units were analyzed based on the respondents in the research. The statistic results suggest a substantial positive effect of market orientation on product innovation performance. Under the condition of incremental innovativeness among the samples, the more innovative the product is, the more improvements in product innovation performance would be achieved. A variety of particular interdepartmental integration mechanisms have been certified to lend more supports to establishing market orientation and improving product innovation performance.展开更多
To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the...To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the alloy across different planes were investigated.The anisotropy of SLM-fabricated Ti-6Al-4V alloys was analyzed,and the electron backscatter diffraction technique was used to investigate the influence of different grain types and orientations on the stress-strain distribution at various scales.Results reveal that in room-temperature compression tests at a strain rate of 10^(-3) s^(-1),both the compressive yield strength and microhardness vary along the deposition direction,indicating a certain degree of mechanical property anisotropy.The alloy exhibits a columnar microstructure;along the deposition direction,the grains appear equiaxed,and they have internal hexagonal close-packed(hcp)α/α'martensitic structure.α'phase has a preferential orientation approximately along the<0001>direction.Anisotropy arises from the high aspect ratio of columnar grains,along with the weak texture of the microstructure and low symmetry of the hcp crystal structure.展开更多
In the context of the global energy low-carbon transition,phase change energy storage technology becomes a key technology to solve the problem of intermittent renewable energy.Oriented phase change composites(OCPCMs)r...In the context of the global energy low-carbon transition,phase change energy storage technology becomes a key technology to solve the problem of intermittent renewable energy.Oriented phase change composites(OCPCMs)receive widespread attention in practical energy storage applications due to their unique oriented thermally conductive structure,which achieves significant thermal conductivity enhancement in specific directions while retaining the high energy storage capacity of the phase change components.This review systematically summarizes the overall analysis of OCPCMs from synthesis and preparation to application scenarios in recent years.Herein,we introduce the analysis of the heat transfer mechanism of the materials and explore the advantages of the oriented structure in OCPCMs in the heat transfer behavior from a bionic perspective.We then focus on summarizing and generalizing the methods for preparing OCPCMs,giving suggestions for suitable methods according to different scenarios.Besides,we discuss the application of finite element simulation methods to the monitoring of the thermal management behavior of OCPCMs,and look into the potential future application areas of such materials.Finally,it is hoped that this review will provide guidance for the academic community in developing high-performance OCPCMs.展开更多
Optical tweezers technology has the characteristics of noncontact manipulation in three dimensions and steerable separation in solutions,and could be applied to obtain a separated sperm with high quality for intracyto...Optical tweezers technology has the characteristics of noncontact manipulation in three dimensions and steerable separation in solutions,and could be applied to obtain a separated sperm with high quality for intracytoplasmic sperm injection(ICSI).However,the effects of optical tweezers on sperm motility are still unclear.To elucidate the effects on sperm motility for optical tweezers,we systematically investigated the correlation between motility parameters and the parameters of optical tweezers(wavelength,power,trapping duration,and trapping orientation).Under three systems of optical tweezers with different laser wavelengths(1064,850,and 785 nm),the nine motility parameters of free swimming were mainly affected by trapping orientation(vertical/horizontal)and trapping duration.When 850 nm laser and 1064 nm laser are used,vertical trapping significantly reduces sperm free-swimming capability with prolonged exposure time,whereas horizontal trapping exhibits relatively minor interference on sperm motility.Notably,the 785 nm laser does not induce statistically significant changes in key parameters of sperm motility under any experimental conditions(trapping orientation and duration).For the rolling frequency of trapped sperm,horizontal trapping for three wavelengths has a negligible effect compared with vertical trapping,especially for the 785 nm laser.In conclusion,horizontal trapping can preserve sperm motility under low power(below 140mW at 1064 nm,below 100mW at 850nm,below 60mW at 785 nm)and short duration(below 4 min).This trapping duration is suffcient for the separation procedure of single live sperm in ICSI.This study provides critical parameter optimization guidelines for the safe application of optical tweezers technology in reproductive medicine.展开更多
The mechanical performance of exceedingly soft materials such as Ag is significantly influenced by various working conditions.Therefore,this study systematically investigates the effects of crack geometry,substrate cr...The mechanical performance of exceedingly soft materials such as Ag is significantly influenced by various working conditions.Therefore,this study systematically investigates the effects of crack geometry,substrate crystal orientation,and indenter shape on crack propagation.The mechanical response of Ag is analyzed using the quasi-continuum(QC)method.A pre-crack with a predefined depth and angle was introduced to initiate fracture behavior.The results show that when the pre-crack height is 50 A,the crack propagates rapidly as the imprint depth increases from0 to 7 A,grows steadily up to 15 A,and then accelerates sharply between 15 and 20 A.For other pre-crack heights,crack propagation occurs at a relatively faster rate.Substrates with[100],[010],and[001]crystal orientations promote crack extension,while the onset of plastic deformation(referred to as the yield point in this study)and the fracture strength both increase with increasing pre-crack height.The yield point,fracture strength,and stress intensity factors are highly sensitive to the pre-crack height.When the pre-crack angle is 90○,the fracture strength reaches its maximum of 0.2%higher than that of the uncracked sample-whereas at 0○,it reaches its minimum,still 53.8%higher than that of the uncracked sample.The sample model is conducted using AutoCAD software.The optimized quasicontinuum(QC)method is used to investigate the effects of different crack geometries,substrate crystal orientations,and indenter shapes on the crack extension of Ag material.Baskes and Dow(FBD)potential is borrowed to describe the interaction forces between Ag-Ag,Ni-Ag,and Ni-Ni.展开更多
Objectives:Non-suicidal self-injury(NSSI)represents a prominent and escalating concern within mental health,associated with considerable psychological and physical dangers.Peer victimization is identified as a signifi...Objectives:Non-suicidal self-injury(NSSI)represents a prominent and escalating concern within mental health,associated with considerable psychological and physical dangers.Peer victimization is identified as a significant predictor of NSSI behavior.Although prior research has explored the association between peer victimization and NSSI,the mechanisms underlying this relationship remain insufficiently understood.Utilizing social information processing theory frameworks,the present study seeks to examine the sequential mediating roles of a cognitive factor,future orientation,and a behavioral factor,social withdrawal,in middle school students.Methods:A cross-sectional survey was administered in China,involving 528 participants(261 females and 267 males;Meanage=13.71,standard deviation[SD]=0.93).Participants completed self-report measures assessing peer victimization via the Delaware Bullying Victimization Scale-Student Version,NSSI via the Adolescents Self-Harm Scale,future orientation via the Adolescent Future Orientation Questionnaire,and social withdrawal via the Social Withdrawal Questionnaire.Results:Findings indicated a significant positive correlation between peer victimization and NSSI(r=0.30,p<0.01).Additionally,future orientation and social withdrawal functioned as serial mediators,with an indirect effect of 0.01(95%CI:[0.01,0.02]),representing 2.70%of the total effect(𝛽=0.37,95%CI:[0.25,0.47]).Conclusions:The findings endorse a theoretical framework in which negative future outlook and social withdrawal are sequentially linked within the relationship between peer victimization and NSSI.Although the serial indirect effect observed is modest,it delineates a distinct associative pattern that characterizes adolescents subjected to victimization.These results carry practical significance for school-based intervention programs,indicating that targeting future perspectives and social connections may enhance strategies for preventing NSSI.展开更多
Discontinuities in rock masses critically impact the stability and safety of underground engineering.Mainstream discontinuities identificationmethods,which rely on normal vector estimation and clustering algorithms,su...Discontinuities in rock masses critically impact the stability and safety of underground engineering.Mainstream discontinuities identificationmethods,which rely on normal vector estimation and clustering algorithms,suffer from accuracy degradation,omission of critical discontinuities when orientation density is unevenly distributed,and need manual intervention.To overcome these limitations,this paper introduces a novel discontinuities identificationmethod based on geometric feature analysis of rock mass.By analyzing spatial distribution variability of point cloud and integrating an adaptive region growing algorithm,the method accurately detects independent discontinuities under complex geological conditions.Given that rock mass orientations typically follow a Fisher distribution,an adaptive hierarchical clustering algorithm based on statistical analysis is employed to automatically determine the optimal number of structural sets,eliminating the need for preset clusters or thresholds inherent in traditional methods.The proposed approach effectively handles diverse rock mass shapes and sizes,leveraging both local and global geometric features to minimize noise interference.Experimental validation on three real-world rock mass models,alongside comparisons with three conventional directional clustering algorithms,demonstrates superior accuracy and robustness in identifying optimal discontinuity sets.The proposed method offers a reliable and efficienttool for discontinuities detection and grouping in underground engineering,significantlyenhancing design and construction outcomes.展开更多
This study experimentally investigates complex wave structures and flow characteristics in a transonic free jet using two high-resolution optical diagnostics techniques:tomographic particle image velocimetry(Tomo-PIV)...This study experimentally investigates complex wave structures and flow characteristics in a transonic free jet using two high-resolution optical diagnostics techniques:tomographic particle image velocimetry(Tomo-PIV)and tomographic background oriented schlieren(Tomo-BOS).The measurements reveal three typical flow features in the jet:the potential core,shock cells,and shear layers.Notably,the shear layer displays significant velocity gradient variations across the lip line and plays a critical role in pressure regulation.The first invariant of the velocity gradient tensor,P,effectively characterizes local compressibility effects,facilitating the identification of key flow structures.In conjunction with-Q_(s)analysis,the results emphasize shear-driven deformation and the radial decay of wave intensity.Overall,the study demonstrates that current experimental techniques enable preliminary quantitative evaluation of transonic wave phenomena,providing valuable tools for the analysis of compressible flows.展开更多
In Wuhu,urban renewal has not only transformed the development process,but improved people’s lives.DURING the 14th Five-Year Plan period(2021-2025),urban renewal has served as a crucial measure to promote high-qualit...In Wuhu,urban renewal has not only transformed the development process,but improved people’s lives.DURING the 14th Five-Year Plan period(2021-2025),urban renewal has served as a crucial measure to promote high-quality urban development and continuously meet people’s growing aspirations for a better life.Wuhu,in central China’s Anhui Province,has consistently enhanced its urban functions and services to build a modern,people-oriented city that is innovative,livable,beautiful,resilient,and smart.展开更多
Aqueous zinc-ion batteries(AZIBs)are currently confronted with the challenge of achieving long-term cyclic stability under high current densities.This issue is primarily attributed to the excessive growth of dendrites...Aqueous zinc-ion batteries(AZIBs)are currently confronted with the challenge of achieving long-term cyclic stability under high current densities.This issue is primarily attributed to the excessive growth of dendrites and the occurrence of significant side reactions.Herein,sucralose(SCL),as an electrolyte additive,has been used to promote the exposure of the Zn(002)texture.The introduction of SCL can adjust the Zn~(2+)nucleation and diffusion along different crystal facets,promoting the exposure of the Zn(002)texture.By substituting water molecules in the[Zn(H_(2)O)_(6)]~(2+),SCL reconfigures the hydrogen bond network in the electrolyte,reconstructing the solvation structure and suppressing the hydrogen evolution reaction.Consequently,the Zn//Zn symmetric battery exhibits long-term cycling stability of over 4900 h at 1 mA cm^(-2)-1 mAh cm^(-2).Even at a harsh condition of 30 mA cm^(-2)-30 mAh cm^(-2)(DOD=73.3%),it can stably cycle for 171 h.The CE of the Zn//Cu half battery reaches 99.61% at 0.2 mA cm^(-2)with 0.2 mAh cm^(-2).Employing the optimized electrolyte,after 500 cycles,a high specific capacity of 420 mAh g^(-1)can be retained for the NH_4V_4O_(10)//Zn full battery at 500 mA g^(-1),corresponding to a capacity retention of 90.7%.展开更多
The effects of initial spin orientation on the final electron beam polarization in laser wakefield acceleration in a pre-polarized plasma are investigated theoretically and numerically.From the results of variation of...The effects of initial spin orientation on the final electron beam polarization in laser wakefield acceleration in a pre-polarized plasma are investigated theoretically and numerically.From the results of variation of the initial spin direction,the spin dynamics of the electron beam are found to depend on the self-injection mechanism.The effects of wakefields and laser fields are studied using test particle dynamics and particle-in-cell simulations based on the Thomas-Bargmann-Michel-Telegdi equation.Compared with transverse injection,longitudinal injection is found to be preferable for obtaining a highly polarized electron beam.展开更多
Laser remelting(LR)was used as an auxiliary post-treatment process for the Ti6Al4V titanium alloys fabricated by laser powder bed fusion(LPBF).Optical microscope(OM),scanning electron microscope(SEM)and electron back ...Laser remelting(LR)was used as an auxiliary post-treatment process for the Ti6Al4V titanium alloys fabricated by laser powder bed fusion(LPBF).Optical microscope(OM),scanning electron microscope(SEM)and electron back scattering diffraction(EBSD)observations showed that the grains in melted zone(MZ)transformed into equiaxial grains with an average size of 1.31μm,and the grains in heat affected zone(HAZ)were refined.Moreover,the texture intensity dropped significantly from 13.86 to 6.35 in MZ and 10.79 in HAZ.The temperature gradient(G)to solidification rate(R)ratio decreased when the laser scanning speed slowed down to a certain extent in the LR process,which effectively improved the highly preferred orientation and filled the hole defects in the surface of LPBF-Ti6Al4V.Furthermore,the hardness,wear resistance and corrosion resistance of the surface of the LPBF samples were improved by LR treatment.展开更多
The creep response,mechanical properties,and microstructure evolution of the Al−Zn−Mg−Cu alloy were investigated under different initial heat treatment conditions.The results indicate that the density of geometrically...The creep response,mechanical properties,and microstructure evolution of the Al−Zn−Mg−Cu alloy were investigated under different initial heat treatment conditions.The results indicate that the density of geometrically necessary dislocations(GNDs)increases during the initial creep stage(<0.5 h)and undergoes dynamic changes in the stable creep stage.During creep aging,the dislocation distribution within the grains becomes more uniform,and additional subgrains are formed.The key factors influencing creep behavior are crystal orientation and the degree of initial precipitation.Grains oriented in the<001>and<101>directions are more susceptible to deformation during the creep process.Based on a strength model,the inhibitory effects of the η'phase in T6 specimens and the GP I zone in T4 specimens on dislocation motion were evaluated.This study demonstrates that selecting an appropriate initial precipitation state is an effective strategy to enhance the creep aging response and to produce high-performance components.展开更多
Systematically analyzing the impact mechanisms of policy on Land Use Conflict(LUC)is crucial for constructing effective conflict mitigation strategies.However,previous research on how policy influences LUC remains rel...Systematically analyzing the impact mechanisms of policy on Land Use Conflict(LUC)is crucial for constructing effective conflict mitigation strategies.However,previous research on how policy influences LUC remains relatively limited.Focusing on the indirect driving role of policy on LUC,this study proposed County Development Level(CDL)under Major Function Oriented Zone Planning(MFOZP)guidance as an intermediary variable,bridging the implicit influence of MFOZP and the explicit changes in LUC.Using the Beijing-Tianjin-Hebei(BTH)region in China as a case study,we analyzed the spatio-temporal evolution characteristics of LUC and CDL for the periods 2000-2010 and 2010-2020,before and after MFOZP implementation.Panel models and Geographically Weighted Regression(GWR)were employed to explore the mechanism by which CDL influences LUC under MFOZP guidance.The results show that:1)MFOZP implementation effectively alleviates land use pressure from regional development,with LUC continuously declining at a rate of 2.41%,while CDL exhibits slight growth(3.84%),during 2010-2020.2)Under MFOZP guidance,CDL reduces pressure on Land Use Structure Conflict(LUSC)and Land Use Process Conflict(LUPC),enhances its inhibitory effect on Land Use Function Conflict(LUFC),and significantly contributes to LUC coordination,with notable spatial heterogeneity.3)The coupling relationship between CDL and LUC has improved post-implementation.Based on this,tailored LUC coordination strategies are proposed for different functional zones.This study confirms the effectiveness of MFOZP in coordinating LUC and provides a scientific reference for LUC research under policy frameworks and the governance of LUC in the BTH region.展开更多
Some patients with systemic lupus erythematosus experience neuropsychiatric symptoms.Although magnetic resonance imaging can detect abnormal signals in the white matter of the brain,conventional methods often struggle...Some patients with systemic lupus erythematosus experience neuropsychiatric symptoms.Although magnetic resonance imaging can detect abnormal signals in the white matter of the brain,conventional methods often struggle to accurately capture microstructural changes.Various diffusion models have been used to study white matter in systemic lupus erythematosus;however,comparative analyses of their sensitivity and specificity for detecting microstructural changes remain insufficient.To address this,our team designed a diagnostic trial that used multimodal diffusion imaging techniques to observe white matter microstructural changes in patients with systemic lupus erythematosus who had neuropsychiatric symptoms,with an aim to identify key diagnostic biomarkers for these patients.Patients with active lupus who received treatment at the Department of Rheumatology and Immunology,The First Affiliated Hospital of China Medical University,from September 2023 to March 2024 were recruited.According to the standards of the American College of Rheumatology,patients with systemic lupus erythematosus who had neuropsychiatric symptoms were assigned to the systemic lupus erythematosus group,whereas those without neuropsychiatric symptoms were assigned to the non-systemic lupus erythematosus group.Additionally,healthy volunteers matched by region,sex,and age were recruited as controls.All three groups underwent the same diffusion magnetic resonance imaging examination protocol to compare differences in diffusion parameters.Advanced diffusion imaging models were able to sensitively detect microstructural changes in the white matter fibers of patients with systemic lupus erythematosus who had neuropsychiatric symptoms,with specific diffusion parameters showing significant abnormalities in key brain regions.In the left superior longitudinal fasciculus subregion and the right thalamic radiations of patients with systemic lupus erythematosus who had neuropsychiatric symptoms,we also identified abnormal diffusion characteristics that were clearly correlated with disease activity,suggesting that microstructural changes in these areas may reflect the dynamic process of neuroinflammatory damage.The present study addresses critical challenges in the diagnosis of systemic lupus erythematosus by identifying specific white matter imaging biomarkers and elucidating the association between microstructural damage and clinical manifestations.The main contributions of our study include:1)establishing axial regression probability parameters from mean apparent propagator magnetic resonance imaging as sensitive biomarkers for systemic lupus erythematosus,particularly in the third subregion of the left superior longitudinal fasciculus;2)demonstrating that multimodal diffusion imaging may be superior to conventional diffusion tensor imaging for detecting white matter microstructural abnormalities in patients with systemic lupus erythematosus;and 3)integrating tract-based spatial statistics with clinically relevant analyses to link imaging findings to pathological mechanisms.展开更多
Transparent Al_(2)O_(3) ceramics with grains aligned to the c-axis were prepared by adding platelets with a low aspect ratio into fine equiaxed particles.The mixed powders were formed into green bodies using spontaneo...Transparent Al_(2)O_(3) ceramics with grains aligned to the c-axis were prepared by adding platelets with a low aspect ratio into fine equiaxed particles.The mixed powders were formed into green bodies using spontaneous coagulation casting and sintered by pressureless sintering and hot-isostatic pressure sintering.Zeta potentials and rheological behavior of the slurries,relative densities of green bodies,and orientation and optical properties of sintered bodies were investigated and discussed.The platelet with a high aspect ratio suppressed densification more seriously during sintering than the one with a low aspect ratio.An excellent oriented structure was obtained when 5 wt%platelets with a low aspect ratio were added,and transparent Al_(2)O_(3) ceramics with grains aligned to c-axis were successfully prepared;the in-line transmittance was 78.4%at 600 nm,which is the highest one in the currently reported literature.展开更多
To enhance the robustness and dynamic performance of a self-excited induction generator (SEIG) used in a stand-alone wind energy system (WES), a virtual flux oriented control (VFOC) based on nonlinear super-twisting s...To enhance the robustness and dynamic performance of a self-excited induction generator (SEIG) used in a stand-alone wind energy system (WES), a virtual flux oriented control (VFOC) based on nonlinear super-twisting sliding mode control (STSMC) is adopted. STSMC is used to replace the conventional proportional-integral-Fuzzy Logic Controller (PI-FLC) of the inner current control loops. The combination of the proposed control strategy with space vector modulation (SVM) applied to a PWM rectifier brings many advantages such as reduction in harmonics, and precise and rapid tracking of the references. The performance of the proposed control technique (STSMC-VFOC-SVM) is verified through simulations and compared with the traditional technique (PI-FLC-VFOC-SVM). It shows that the proposed method improves the dynamics of the system with reduced current harmonics. In addition, the use of a virtual flux estimator instead of a phase-locked loop (PLL) eliminates the line voltage sensors and thus increases the reliability of the system.展开更多
基金This work is supported by the National Natural Science Foundation of China[grant numbers 41890820,41771452,41771454,and 41901340]。
文摘Due to the bird’s eye view of remote sensing sensors,the orientational information of an object is a key factor that has to be considered in object detection.To obtain rotating bounding boxes,existing studies either rely on rotated anchoring schemes or adding complex rotating ROI transfer layers,leading to increased computational demand and reduced detection speeds.In this study,we propose a novel internal-external optimized convolutional neural network for arbitrary orientated object detection in optical remote sensing images.For the internal opti-mization,we designed an anchor-based single-shot head detector that adopts the concept of coarse-to-fine detection for two-stage object detection networks.The refined rotating anchors are generated from the coarse detection head module and fed into the refining detection head module with a link of an embedded deformable convolutional layer.For the external optimiza-tion,we propose an IOU balanced loss that addresses the regression challenges related to arbitrary orientated bounding boxes.Experimental results on the DOTA and HRSC2016 bench-mark datasets show that our proposed method outperforms selected methods.
基金the key projects of science and technology of Science&Technology Department of Sichuan Province(No.2018GZ0421)。
文摘Metal organic frameworks(MOFs)has broad application prospect in separation,catalysis,and adsorption.By a facile green method,we successfully fabricated prGO@cHKUST-1 composite membrane with the modification of dopamine and orientated growth of MOFs.Mg/AI-layered double hydroxides(Mg/Al-LDHs)was used as a modulator to obtain cubic HKUST-1(cHKUST-1)with excellent morphology and special properties.Scanning Electron Microscopy(SEM),X-ray diffraction(XRD),and Fourier transform infrared spectroscopy(FTIR)etc.characte rization illustrated successful synthesis of cHKUST-1 and composite membranes.Cubic HKUST-1 can tune the inter-layer spacing of graphene oxide(GO)leading increase in hydrophilicity and flux of the membrane.Meanwhile,the reduction effect of PDA and intercalation effect of MOFs could change the stacked way of GO layers,forming several fuzzy pores and more active sites on membrane surface.The prGO@cHKUST-1 membrane has an excellent rejection for methylene blue(MB)(99.5%)and Congo red(CR)(71.2%).Moreover,the modified membra ne exhibited 10 and 5 times higher permeation flux than that of original GO membrane and prGO membrane,respectively.Thus,using orientated growth of MOFs to synthesize GO based composite membrane will provide useful insights in ultrahigh permeation flux membranes of dye and oil-water emulsion separation.
基金Project supported by the National Key Research and Deveopment Program of China(Grant No.2018YFB1500402)the National Natural Science Foundation of China(Grant Nos.61674084 and 61874167)+5 种基金the Fundamental Research Funds for Central Universities,Chinathe Natural Science Foundation of Tianjin City,China(Grant No.17JCYBJC41400)the Open Fund of the Key Laboratory of Optical Information Science&Technology of Ministry of Education of China(Grant No.2017KFKT014)the 111 Project,China(Grant No.B16027)the International Cooperation Base,China(Grant No.2016D01025)Tianjin International Joint Research and Development Center,China。
文摘Hydrogenated amorphous silicon oxide(a-SiOx:H) is an attractive passivation material to suppress epitaxial growth and reduce the parasitic absorption loss in silicon heterojunction(SHJ) solar cells. In this paper, a-SiOx:H layers on different orientated c-Si substrates are fabricated. An optimal effective lifetime(τ(eff)) of 4743 μs and corresponding implied opencircuit voltage(iV(oc)) of 724 mV are obtained on〈100〉-orientated c-Si wafers. While τ(eff) of 2429 μs and iV_(oc) of 699 mV are achieved on 111-orientated substrate. The FTIR and XPS results indicate that the a-SiOx:H network consists of SiOx(Si-rich), Si–OH, Si–O–SiHx, SiO2 ≡ Si–Si, and O3 ≡ Si–Si. A passivation evolution mechanism is proposed to explain the different passivation results on different c-Si wafers. By modulating the a-SiOx:H layer, the planar silicon heterojunction solar cell can achieve an efficiency of 18.15%.
文摘The effect that the market orientation brings to product innovation performance is reported and the degree of product innovativeness is explored. The interdepartmental integration inside the company is also investigated. A series of hypotheses were developed aiming at presenting a conceptual framework to clarify how market orientation contributes to product innovation performance-moderated by the degree of product innovativeness and affected by the interdepartmental integration. Survey data from 36 business units were analyzed based on the respondents in the research. The statistic results suggest a substantial positive effect of market orientation on product innovation performance. Under the condition of incremental innovativeness among the samples, the more innovative the product is, the more improvements in product innovation performance would be achieved. A variety of particular interdepartmental integration mechanisms have been certified to lend more supports to establishing market orientation and improving product innovation performance.
基金National Natural Science Foundation of China(51504138,51674118,52271177)Hunan Provincial Natural Science Foundation of China(2023JJ50181)Supported by State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology(P2024-022)。
文摘To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the alloy across different planes were investigated.The anisotropy of SLM-fabricated Ti-6Al-4V alloys was analyzed,and the electron backscatter diffraction technique was used to investigate the influence of different grain types and orientations on the stress-strain distribution at various scales.Results reveal that in room-temperature compression tests at a strain rate of 10^(-3) s^(-1),both the compressive yield strength and microhardness vary along the deposition direction,indicating a certain degree of mechanical property anisotropy.The alloy exhibits a columnar microstructure;along the deposition direction,the grains appear equiaxed,and they have internal hexagonal close-packed(hcp)α/α'martensitic structure.α'phase has a preferential orientation approximately along the<0001>direction.Anisotropy arises from the high aspect ratio of columnar grains,along with the weak texture of the microstructure and low symmetry of the hcp crystal structure.
基金financially supported by the Fundamental Research Funds for the Central Universities(No.FRF-KST-25-001)the Beijing Natural Science Foundation(No.L253029)。
文摘In the context of the global energy low-carbon transition,phase change energy storage technology becomes a key technology to solve the problem of intermittent renewable energy.Oriented phase change composites(OCPCMs)receive widespread attention in practical energy storage applications due to their unique oriented thermally conductive structure,which achieves significant thermal conductivity enhancement in specific directions while retaining the high energy storage capacity of the phase change components.This review systematically summarizes the overall analysis of OCPCMs from synthesis and preparation to application scenarios in recent years.Herein,we introduce the analysis of the heat transfer mechanism of the materials and explore the advantages of the oriented structure in OCPCMs in the heat transfer behavior from a bionic perspective.We then focus on summarizing and generalizing the methods for preparing OCPCMs,giving suggestions for suitable methods according to different scenarios.Besides,we discuss the application of finite element simulation methods to the monitoring of the thermal management behavior of OCPCMs,and look into the potential future application areas of such materials.Finally,it is hoped that this review will provide guidance for the academic community in developing high-performance OCPCMs.
基金supported by the Natural Science Foundation of Anhui Province in China(2508085MF166)Research Fund of Anhui Institute of Translational Medicine(2024zh-03)+2 种基金Key Scientific Research Foundation of Education Department of Anhui Province(2023AH040083)National Natural Science Foundation of China(12404353)Cultivation Project of Training Young and Middle-aged Teachers in Universities of Anhui Province(DTR2023013).
文摘Optical tweezers technology has the characteristics of noncontact manipulation in three dimensions and steerable separation in solutions,and could be applied to obtain a separated sperm with high quality for intracytoplasmic sperm injection(ICSI).However,the effects of optical tweezers on sperm motility are still unclear.To elucidate the effects on sperm motility for optical tweezers,we systematically investigated the correlation between motility parameters and the parameters of optical tweezers(wavelength,power,trapping duration,and trapping orientation).Under three systems of optical tweezers with different laser wavelengths(1064,850,and 785 nm),the nine motility parameters of free swimming were mainly affected by trapping orientation(vertical/horizontal)and trapping duration.When 850 nm laser and 1064 nm laser are used,vertical trapping significantly reduces sperm free-swimming capability with prolonged exposure time,whereas horizontal trapping exhibits relatively minor interference on sperm motility.Notably,the 785 nm laser does not induce statistically significant changes in key parameters of sperm motility under any experimental conditions(trapping orientation and duration).For the rolling frequency of trapped sperm,horizontal trapping for three wavelengths has a negligible effect compared with vertical trapping,especially for the 785 nm laser.In conclusion,horizontal trapping can preserve sperm motility under low power(below 140mW at 1064 nm,below 100mW at 850nm,below 60mW at 785 nm)and short duration(below 4 min).This trapping duration is suffcient for the separation procedure of single live sperm in ICSI.This study provides critical parameter optimization guidelines for the safe application of optical tweezers technology in reproductive medicine.
基金by the Industry–Academia Cooperation Project No.113A00262(Te-Hua Fang).URLs to the sponsor websites are available at:https://www.nstc.gov.tw.
文摘The mechanical performance of exceedingly soft materials such as Ag is significantly influenced by various working conditions.Therefore,this study systematically investigates the effects of crack geometry,substrate crystal orientation,and indenter shape on crack propagation.The mechanical response of Ag is analyzed using the quasi-continuum(QC)method.A pre-crack with a predefined depth and angle was introduced to initiate fracture behavior.The results show that when the pre-crack height is 50 A,the crack propagates rapidly as the imprint depth increases from0 to 7 A,grows steadily up to 15 A,and then accelerates sharply between 15 and 20 A.For other pre-crack heights,crack propagation occurs at a relatively faster rate.Substrates with[100],[010],and[001]crystal orientations promote crack extension,while the onset of plastic deformation(referred to as the yield point in this study)and the fracture strength both increase with increasing pre-crack height.The yield point,fracture strength,and stress intensity factors are highly sensitive to the pre-crack height.When the pre-crack angle is 90○,the fracture strength reaches its maximum of 0.2%higher than that of the uncracked sample-whereas at 0○,it reaches its minimum,still 53.8%higher than that of the uncracked sample.The sample model is conducted using AutoCAD software.The optimized quasicontinuum(QC)method is used to investigate the effects of different crack geometries,substrate crystal orientations,and indenter shapes on the crack extension of Ag material.Baskes and Dow(FBD)potential is borrowed to describe the interaction forces between Ag-Ag,Ni-Ag,and Ni-Ni.
基金supported by 2024 The Basic Ability Improvement Project for Young and Middle-aged Teachers of Colleges and Universities in Guangxi(No.2024KY0165)2024 Guangxi Minzu University General Research Project(Humanities and Social Sciences Category,No.2024MDSKYB20)2022 Annual Teaching and Research Project of Shiyuan College of Nanning Normal University(No.2022JY13).
文摘Objectives:Non-suicidal self-injury(NSSI)represents a prominent and escalating concern within mental health,associated with considerable psychological and physical dangers.Peer victimization is identified as a significant predictor of NSSI behavior.Although prior research has explored the association between peer victimization and NSSI,the mechanisms underlying this relationship remain insufficiently understood.Utilizing social information processing theory frameworks,the present study seeks to examine the sequential mediating roles of a cognitive factor,future orientation,and a behavioral factor,social withdrawal,in middle school students.Methods:A cross-sectional survey was administered in China,involving 528 participants(261 females and 267 males;Meanage=13.71,standard deviation[SD]=0.93).Participants completed self-report measures assessing peer victimization via the Delaware Bullying Victimization Scale-Student Version,NSSI via the Adolescents Self-Harm Scale,future orientation via the Adolescent Future Orientation Questionnaire,and social withdrawal via the Social Withdrawal Questionnaire.Results:Findings indicated a significant positive correlation between peer victimization and NSSI(r=0.30,p<0.01).Additionally,future orientation and social withdrawal functioned as serial mediators,with an indirect effect of 0.01(95%CI:[0.01,0.02]),representing 2.70%of the total effect(𝛽=0.37,95%CI:[0.25,0.47]).Conclusions:The findings endorse a theoretical framework in which negative future outlook and social withdrawal are sequentially linked within the relationship between peer victimization and NSSI.Although the serial indirect effect observed is modest,it delineates a distinct associative pattern that characterizes adolescents subjected to victimization.These results carry practical significance for school-based intervention programs,indicating that targeting future perspectives and social connections may enhance strategies for preventing NSSI.
基金the National Key Research and Development Program of China(Grant No.2023YFC3009400).
文摘Discontinuities in rock masses critically impact the stability and safety of underground engineering.Mainstream discontinuities identificationmethods,which rely on normal vector estimation and clustering algorithms,suffer from accuracy degradation,omission of critical discontinuities when orientation density is unevenly distributed,and need manual intervention.To overcome these limitations,this paper introduces a novel discontinuities identificationmethod based on geometric feature analysis of rock mass.By analyzing spatial distribution variability of point cloud and integrating an adaptive region growing algorithm,the method accurately detects independent discontinuities under complex geological conditions.Given that rock mass orientations typically follow a Fisher distribution,an adaptive hierarchical clustering algorithm based on statistical analysis is employed to automatically determine the optimal number of structural sets,eliminating the need for preset clusters or thresholds inherent in traditional methods.The proposed approach effectively handles diverse rock mass shapes and sizes,leveraging both local and global geometric features to minimize noise interference.Experimental validation on three real-world rock mass models,alongside comparisons with three conventional directional clustering algorithms,demonstrates superior accuracy and robustness in identifying optimal discontinuity sets.The proposed method offers a reliable and efficienttool for discontinuities detection and grouping in underground engineering,significantlyenhancing design and construction outcomes.
文摘This study experimentally investigates complex wave structures and flow characteristics in a transonic free jet using two high-resolution optical diagnostics techniques:tomographic particle image velocimetry(Tomo-PIV)and tomographic background oriented schlieren(Tomo-BOS).The measurements reveal three typical flow features in the jet:the potential core,shock cells,and shear layers.Notably,the shear layer displays significant velocity gradient variations across the lip line and plays a critical role in pressure regulation.The first invariant of the velocity gradient tensor,P,effectively characterizes local compressibility effects,facilitating the identification of key flow structures.In conjunction with-Q_(s)analysis,the results emphasize shear-driven deformation and the radial decay of wave intensity.Overall,the study demonstrates that current experimental techniques enable preliminary quantitative evaluation of transonic wave phenomena,providing valuable tools for the analysis of compressible flows.
文摘In Wuhu,urban renewal has not only transformed the development process,but improved people’s lives.DURING the 14th Five-Year Plan period(2021-2025),urban renewal has served as a crucial measure to promote high-quality urban development and continuously meet people’s growing aspirations for a better life.Wuhu,in central China’s Anhui Province,has consistently enhanced its urban functions and services to build a modern,people-oriented city that is innovative,livable,beautiful,resilient,and smart.
基金supported by the Anhui Provincial Science and Technology Innovation Initiative(202423i08050051)the Anhui Provincial Natural Science Foundation(2408085MB029)+1 种基金the HFIPS Director’s Fund(YZJJGGZX202201)the Natural Science Foundation of Hebei Province of China(B2024402018)。
文摘Aqueous zinc-ion batteries(AZIBs)are currently confronted with the challenge of achieving long-term cyclic stability under high current densities.This issue is primarily attributed to the excessive growth of dendrites and the occurrence of significant side reactions.Herein,sucralose(SCL),as an electrolyte additive,has been used to promote the exposure of the Zn(002)texture.The introduction of SCL can adjust the Zn~(2+)nucleation and diffusion along different crystal facets,promoting the exposure of the Zn(002)texture.By substituting water molecules in the[Zn(H_(2)O)_(6)]~(2+),SCL reconfigures the hydrogen bond network in the electrolyte,reconstructing the solvation structure and suppressing the hydrogen evolution reaction.Consequently,the Zn//Zn symmetric battery exhibits long-term cycling stability of over 4900 h at 1 mA cm^(-2)-1 mAh cm^(-2).Even at a harsh condition of 30 mA cm^(-2)-30 mAh cm^(-2)(DOD=73.3%),it can stably cycle for 171 h.The CE of the Zn//Cu half battery reaches 99.61% at 0.2 mA cm^(-2)with 0.2 mAh cm^(-2).Employing the optimized electrolyte,after 500 cycles,a high specific capacity of 420 mAh g^(-1)can be retained for the NH_4V_4O_(10)//Zn full battery at 500 mA g^(-1),corresponding to a capacity retention of 90.7%.
基金supported by the National Natural Science Foundation of China(Grant Nos.11804348,11775056,11975154,12225505,and 12405281)the Science Challenge(Project No.TZ2018005)+2 种基金supported by the Shanghai Pujiang Program(Grant No.23PJ1414600)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0890203)supported by the Accelerator Technology Helmholtz Infrastructure consortium ATHENA.
文摘The effects of initial spin orientation on the final electron beam polarization in laser wakefield acceleration in a pre-polarized plasma are investigated theoretically and numerically.From the results of variation of the initial spin direction,the spin dynamics of the electron beam are found to depend on the self-injection mechanism.The effects of wakefields and laser fields are studied using test particle dynamics and particle-in-cell simulations based on the Thomas-Bargmann-Michel-Telegdi equation.Compared with transverse injection,longitudinal injection is found to be preferable for obtaining a highly polarized electron beam.
基金supported by the National Natural Science Foundation of China(No.51871243)the National Key Laboratory of Strength and Structural Integrity,China(No.ASSIKFJJ202304001)+3 种基金the State Key Laboratory of Precision Blasting and Hubei Key Laboratory of Blasting Engineering,China(No.PBSKL2022C01)the Guangdong-Hong Kong-Macao Joint Laboratory for Neutron Scattering Science and Technology,China(No.HT-CSNS-DG-CD-0092/2021)the Shock and Vibration of Engineering Materials and Structures Key Laboratory of Sichuan Province,China(No.22kfgk06)the Hubei Longzhong Laboratory,China(No.2022KF-08)。
文摘Laser remelting(LR)was used as an auxiliary post-treatment process for the Ti6Al4V titanium alloys fabricated by laser powder bed fusion(LPBF).Optical microscope(OM),scanning electron microscope(SEM)and electron back scattering diffraction(EBSD)observations showed that the grains in melted zone(MZ)transformed into equiaxial grains with an average size of 1.31μm,and the grains in heat affected zone(HAZ)were refined.Moreover,the texture intensity dropped significantly from 13.86 to 6.35 in MZ and 10.79 in HAZ.The temperature gradient(G)to solidification rate(R)ratio decreased when the laser scanning speed slowed down to a certain extent in the LR process,which effectively improved the highly preferred orientation and filled the hole defects in the surface of LPBF-Ti6Al4V.Furthermore,the hardness,wear resistance and corrosion resistance of the surface of the LPBF samples were improved by LR treatment.
基金support from the National Key Research and Development Program of China(No.2023YFB3710501)。
文摘The creep response,mechanical properties,and microstructure evolution of the Al−Zn−Mg−Cu alloy were investigated under different initial heat treatment conditions.The results indicate that the density of geometrically necessary dislocations(GNDs)increases during the initial creep stage(<0.5 h)and undergoes dynamic changes in the stable creep stage.During creep aging,the dislocation distribution within the grains becomes more uniform,and additional subgrains are formed.The key factors influencing creep behavior are crystal orientation and the degree of initial precipitation.Grains oriented in the<001>and<101>directions are more susceptible to deformation during the creep process.Based on a strength model,the inhibitory effects of the η'phase in T6 specimens and the GP I zone in T4 specimens on dislocation motion were evaluated.This study demonstrates that selecting an appropriate initial precipitation state is an effective strategy to enhance the creep aging response and to produce high-performance components.
基金Under the auspices of the National Key Research and Development Program of China(No.2018YFD1100803)the Fundamental Research Fund for the Central Universities(Ph.D.Top Innovative Talents Fund of CUMTB)(No.BBJ2024029)。
文摘Systematically analyzing the impact mechanisms of policy on Land Use Conflict(LUC)is crucial for constructing effective conflict mitigation strategies.However,previous research on how policy influences LUC remains relatively limited.Focusing on the indirect driving role of policy on LUC,this study proposed County Development Level(CDL)under Major Function Oriented Zone Planning(MFOZP)guidance as an intermediary variable,bridging the implicit influence of MFOZP and the explicit changes in LUC.Using the Beijing-Tianjin-Hebei(BTH)region in China as a case study,we analyzed the spatio-temporal evolution characteristics of LUC and CDL for the periods 2000-2010 and 2010-2020,before and after MFOZP implementation.Panel models and Geographically Weighted Regression(GWR)were employed to explore the mechanism by which CDL influences LUC under MFOZP guidance.The results show that:1)MFOZP implementation effectively alleviates land use pressure from regional development,with LUC continuously declining at a rate of 2.41%,while CDL exhibits slight growth(3.84%),during 2010-2020.2)Under MFOZP guidance,CDL reduces pressure on Land Use Structure Conflict(LUSC)and Land Use Process Conflict(LUPC),enhances its inhibitory effect on Land Use Function Conflict(LUFC),and significantly contributes to LUC coordination,with notable spatial heterogeneity.3)The coupling relationship between CDL and LUC has improved post-implementation.Based on this,tailored LUC coordination strategies are proposed for different functional zones.This study confirms the effectiveness of MFOZP in coordinating LUC and provides a scientific reference for LUC research under policy frameworks and the governance of LUC in the BTH region.
基金supported by the National Natural Science Foundation Joint Fund,No.U22A20309(to PY)the Natural Science Foundation of LiaoningProvince,No.2023-MS-07(to HuL)the Unveiling Key Scientific and Technological Projects of Liaoning Province,No.2021JH1/10400051(to HuL).
文摘Some patients with systemic lupus erythematosus experience neuropsychiatric symptoms.Although magnetic resonance imaging can detect abnormal signals in the white matter of the brain,conventional methods often struggle to accurately capture microstructural changes.Various diffusion models have been used to study white matter in systemic lupus erythematosus;however,comparative analyses of their sensitivity and specificity for detecting microstructural changes remain insufficient.To address this,our team designed a diagnostic trial that used multimodal diffusion imaging techniques to observe white matter microstructural changes in patients with systemic lupus erythematosus who had neuropsychiatric symptoms,with an aim to identify key diagnostic biomarkers for these patients.Patients with active lupus who received treatment at the Department of Rheumatology and Immunology,The First Affiliated Hospital of China Medical University,from September 2023 to March 2024 were recruited.According to the standards of the American College of Rheumatology,patients with systemic lupus erythematosus who had neuropsychiatric symptoms were assigned to the systemic lupus erythematosus group,whereas those without neuropsychiatric symptoms were assigned to the non-systemic lupus erythematosus group.Additionally,healthy volunteers matched by region,sex,and age were recruited as controls.All three groups underwent the same diffusion magnetic resonance imaging examination protocol to compare differences in diffusion parameters.Advanced diffusion imaging models were able to sensitively detect microstructural changes in the white matter fibers of patients with systemic lupus erythematosus who had neuropsychiatric symptoms,with specific diffusion parameters showing significant abnormalities in key brain regions.In the left superior longitudinal fasciculus subregion and the right thalamic radiations of patients with systemic lupus erythematosus who had neuropsychiatric symptoms,we also identified abnormal diffusion characteristics that were clearly correlated with disease activity,suggesting that microstructural changes in these areas may reflect the dynamic process of neuroinflammatory damage.The present study addresses critical challenges in the diagnosis of systemic lupus erythematosus by identifying specific white matter imaging biomarkers and elucidating the association between microstructural damage and clinical manifestations.The main contributions of our study include:1)establishing axial regression probability parameters from mean apparent propagator magnetic resonance imaging as sensitive biomarkers for systemic lupus erythematosus,particularly in the third subregion of the left superior longitudinal fasciculus;2)demonstrating that multimodal diffusion imaging may be superior to conventional diffusion tensor imaging for detecting white matter microstructural abnormalities in patients with systemic lupus erythematosus;and 3)integrating tract-based spatial statistics with clinically relevant analyses to link imaging findings to pathological mechanisms.
基金This work was supported by the National Natural Science Foundation of China(Nos.51772309 and 52130207).The authors thank Prof.Jing WANG(Dalian University of Technology)for the synthesis of Al2O3 platelets.
文摘Transparent Al_(2)O_(3) ceramics with grains aligned to the c-axis were prepared by adding platelets with a low aspect ratio into fine equiaxed particles.The mixed powders were formed into green bodies using spontaneous coagulation casting and sintered by pressureless sintering and hot-isostatic pressure sintering.Zeta potentials and rheological behavior of the slurries,relative densities of green bodies,and orientation and optical properties of sintered bodies were investigated and discussed.The platelet with a high aspect ratio suppressed densification more seriously during sintering than the one with a low aspect ratio.An excellent oriented structure was obtained when 5 wt%platelets with a low aspect ratio were added,and transparent Al_(2)O_(3) ceramics with grains aligned to c-axis were successfully prepared;the in-line transmittance was 78.4%at 600 nm,which is the highest one in the currently reported literature.
基金supported by the:Direction Générale de la Recherche Scientifique et du Développement Technologique(DGRSDT).
文摘To enhance the robustness and dynamic performance of a self-excited induction generator (SEIG) used in a stand-alone wind energy system (WES), a virtual flux oriented control (VFOC) based on nonlinear super-twisting sliding mode control (STSMC) is adopted. STSMC is used to replace the conventional proportional-integral-Fuzzy Logic Controller (PI-FLC) of the inner current control loops. The combination of the proposed control strategy with space vector modulation (SVM) applied to a PWM rectifier brings many advantages such as reduction in harmonics, and precise and rapid tracking of the references. The performance of the proposed control technique (STSMC-VFOC-SVM) is verified through simulations and compared with the traditional technique (PI-FLC-VFOC-SVM). It shows that the proposed method improves the dynamics of the system with reduced current harmonics. In addition, the use of a virtual flux estimator instead of a phase-locked loop (PLL) eliminates the line voltage sensors and thus increases the reliability of the system.
