Background Dysregulation of lipid metabolism and its consequences on growth performance in young ruminants have attracted attention,especially in the context of alternative feeding strategies.This study aims to elucid...Background Dysregulation of lipid metabolism and its consequences on growth performance in young ruminants have attracted attention,especially in the context of alternative feeding strategies.This study aims to elucidate the effects of milk replacer(MR)feeding on growth,lipid metabolism,colonic epithelial gene expression,colonic microbiota composition and systemic metabolism in goat kids compared to breast milk(BM)feeding,addressing a critical knowledge gap in early life nutrition.Methods Ten female goat kids were divided into 2 groups:those fed breast milk(BM group)and those fed a milk replacer(MR group).Over a period of 28 d,body weight was monitored and blood and tissue samples were collected for biochemical,transcriptomic and metabolomic analyses.Profiling of the colonial microbiota was performed using 16S rRNA gene sequencing.Intestinal microbiota transplantation(IMT)experiments in gnotobiotic mice were per-formed to validate causality.Results MR-fed pups exhibited reduced daily body-weight gain due to impaired lipid metabolism as evidenced by lower serum and liver total cholesterol(TC)and non-esterified fatty acid(NEFA)concentrations.Transcriptomic analysis of the colonic epithelium revealed upregulated genes involved in negative regulation of lipid metabolism,concomitant with microbiota shifts characterized by a decrease in Firmicutes and an increase in Actinobacteria.Specifically,genera such as Bifidobacterium and Prevotella were enriched in the MR group,while Clostridium and Fae-calibacterium were depleted.Metabolomics analyses confirmed alterations in bile acid and fatty acid metabolic path-ways.IMT experiments in mice recapitulated the metabolic phenotype observed in MR-fed goats,confirming the role of the microbiota in modulating host lipid metabolism.Conclusions Milk replacer feeding in goat kids disrupts lipid metabolism and gut microbiota dynamics,result-ing in reduced growth rates and metabolic alterations.These findings highlight the importance of early nutritional intervention on metabolic programming and suggest that modulation of the gut microbiota may be a target for improving growth and metabolic health in ruminants.This study contributes to the understanding of nutritional management strategies in livestock and their impact on animal health and productivity.展开更多
Given the rapid development of advanced information systems,microgrids(MGs)suffer from more potential attacks that affect their operational performance.Conventional distributed secondary control with a small,fixed sam...Given the rapid development of advanced information systems,microgrids(MGs)suffer from more potential attacks that affect their operational performance.Conventional distributed secondary control with a small,fixed sampling time period inevitably causes the wasteful use of communication resources.This paper proposes a self-triggered secondary control scheme under perturbations from false data injection(FDI)attacks.We designed a linear clock for each DG to trigger its controller at aperiodic and intermittent instants.Sub-sequently,a hash-based defense mechanism(HDM)is designed for detecting and eliminating malicious data infiltrated in the MGs.With the aid of HDM,a self-triggered control scheme achieves the secondary control objectives even in the presence of FDI attacks.Rigorous theoretical analyses and simulation results indicate that the introduced secondary control scheme significantly reduces communication costs and enhances the resilience of MGs under FDI attacks.展开更多
With the rapid development of large-scale regional interconnected power grids,the risk of cascading failures under extreme condi-tions,such as natural disasters and military strikes,has increased significantly.To enha...With the rapid development of large-scale regional interconnected power grids,the risk of cascading failures under extreme condi-tions,such as natural disasters and military strikes,has increased significantly.To enhance the response capability of power systems to extreme events,this study focuses on a method for generator coherency detection.To overcome the shortcomings of the traditional slow coherency method,this paper introduces a novel coherent group identification algorithm based on the theory of nonlinear dynam-ical systems.By analyzing the changing trend of the Euclidean norm of the state variable derivatives in the reduced system,the algorithm can accurately identify the magnitude of the disturbances.Based on the slow coherency methods,the algorithm can correctly recognize coherent generator groups by analyzing system characteristics under varying disturbance magnitudes.This improvement enhances the applicability and accuracy of the coherency detection algorithm under extreme conditions,providing support for emergency control and protection in the power system.Simulations and comparison analyses on IEEE 39-bus system are conducted to validate the accuracy and superiority of the proposed coherent generator group identification method under extreme conditions.展开更多
Traditional active power sharing in microgrids,achieved by the distributed average consensus,requires each controller to continuously trigger and communicate with each other,which is a wasteful use of the limited comp...Traditional active power sharing in microgrids,achieved by the distributed average consensus,requires each controller to continuously trigger and communicate with each other,which is a wasteful use of the limited computation and communication resources of the secondary controller.To enhance the efficiency of secondary control,we developed a novel distributed self-triggered active power-sharing control strategy by introducing the signum function and a flexible linear clock.Unlike continuous communication–based controllers,the proposed self-triggered distributed controller prompts distributed generators to perform control actions and share information with their neighbors only at specific time instants monitored by the linear clock.Therefore,this approach results in a significant reduction in both the computation and communication requirements.Moreover,this design naturally avoids Zeno behavior.Furthermore,a modified triggering condition was established to achieve further reductions in computation and communication.The simulation results confirmed that the proposed control scheme achieves distributed active power sharing with very few controller triggers,thereby substantially enhancing the efficacy of secondary control in MGs.展开更多
The dimensionality of quantum materials strongly affects their physical properties.Although many emergent phenomena,such as charge-density wave and Luttinger liquid behavior,are well understood in one-dimensional(1D)s...The dimensionality of quantum materials strongly affects their physical properties.Although many emergent phenomena,such as charge-density wave and Luttinger liquid behavior,are well understood in one-dimensional(1D)systems,the generalization to explore them in higher dimensional systems is still a challenging task.In this study,we aim to bridge this gap by systematically investigating the crystal and electronic structures of molybdenum-oxide family compounds,where the contexture of 1D chains facilitates rich emergent properties.While the quasi-1D chains in these materials share general similarities,such as the motifs made up of MoO_(6)octahedrons,they exhibit vast complexity and remarkable tunability.We disassemble the 1D chains in molybdenum oxides with different dimensions and construct effective models to excellently fit their low-energy electronic structures obtained by ab initio calculations.Furthermore,we discuss the implications of such chains on other physical properties of the materials and the practical significance of the effective models.Our work establishes the molybdenum oxides as simple and tunable model systems for studying and manipulating the dimensionality in quantum systems.展开更多
High-temperature superconductivity(HTSC)remains one of the most challenging and fascinating mysteries in condensed matter physics.Recently,superconductivity with transition temperature exceeding liquid-nitrogen temper...High-temperature superconductivity(HTSC)remains one of the most challenging and fascinating mysteries in condensed matter physics.Recently,superconductivity with transition temperature exceeding liquid-nitrogen temperature is discovered in La_(3)Ni_(2)O_(7) at high pressure,which provides a new platform to explore the unconventional HTSC.In this work,using high-resolution angle-resolved photoemission spectroscopy and ab initio calculation,we systematically investigate the electronic structures of La_(3)Ni_(2)O_(7) at ambient pressure.Our experiments are in nice agreement with ab initio calculations after considering an orbital-dependent band renormalization effect.The strong electron correlation effect pushes a flat band of d_(z^(2))𝑧2 orbital component below the Fermi level(E_(F)),which is predicted to locate right at E_(F) under high pressure.Moreover,the d_(x^(2)−y^(2)) band shows pseudogap-like behavior with suppressed spectral weight and diminished quasiparticle peak near E_(F).Our findings provide important insights into the electronic structure of La_(3)Ni_(2)O_(7),which will shed light on understanding of the unconventional superconductivity in nickelates.展开更多
Recently, giant intrinsic anomalous Hall effect(AHE) has been observed in the materials with kagome lattice.Here, we systematically investigate the influence of high pressure on the AHE in the ferromagnet LiMn_(6)Sn_(...Recently, giant intrinsic anomalous Hall effect(AHE) has been observed in the materials with kagome lattice.Here, we systematically investigate the influence of high pressure on the AHE in the ferromagnet LiMn_(6)Sn_(6) with clean Mn kagome lattice. Our in situ high-pressure Raman spectroscopy indicates that the crystal structure of LiMn_(6)Sn_(6) maintains a hexagonal phase under high pressures up to 8.51 GPa. The anomalous Hall conductivity(AHC) σ_(xy)^(A) remains around 150 Ω^(-1)·cm^(-1), dominated by the intrinsic mechanism. Combined with theoretical calculations, our results indicate that the stable AHE under pressure in Li Mn_(6)Sn_(6) originates from the robust electronic and magnetic structure.展开更多
Using methods such as questionnaire survey and literature review,a survey was conducted on the professional development of physical education teachers in Huaiji County under the background of the new curriculum standa...Using methods such as questionnaire survey and literature review,a survey was conducted on the professional development of physical education teachers in Huaiji County under the background of the new curriculum standards.The research results found that physical education teachers in Huaiji County have a relatively good distribution structure in terms of teaching experience,age,and education level,but the gender ratio and professional title ratio need to be improved.In terms of professional competence,teachers have shown good performance in teaching implementation ability,but there is still room for improvement in teaching design ability.A certain proportion of teachers still express dissatisfaction with professional title promotion,hardware configuration satisfaction,salary and benefits,and school reward mechanisms.Based on this,this study proposes some measures to improve the professional development level of county-level physical education teachers,such as enhancing teachers teaching design and implementation abilities,strengthening the cultivation of technical action demonstration abilities,improving hardware configuration satisfaction and teaching effectiveness reflection level,strengthening guidance and support for teachers professional development,and enhancing the promotion and implementation of post employment training.展开更多
The thermal structure of the lower mantle plays a key role in understanding the dynamic processes of the Earth's evolution and mantle convection.Because intrinsic attenuation in the lower mantle is highly sensitiv...The thermal structure of the lower mantle plays a key role in understanding the dynamic processes of the Earth's evolution and mantle convection.Because intrinsic attenuation in the lower mantle is highly sensitive to temperature,determining of the attenuation of the lower mantle could help us determine its thermal state.We attempted to constrain the attenuation of the lower mantle by measuring the amplitude ratios of p to ScP on the vertical component and s to ScS on the tangential component at short epicentral distances for seismic wave data from deep earthquakes in Northeast China.We calculated the theoretical amplitude ratios of p to ScP and s to ScS by using ray theory and the axial-symmetric spectral element method AxiSEM,as well as by considering the effects of radiation patterns,geometrical spreading,and ScP reflection coefficients.By comparing the observed amplitude ratios with the synthetic results,we constrained the quality factors as Qα≈3,000 and Qβ≈1,300 in the lower mantle beneath Northeast China,which are much larger than those in the preliminary reference Earth model(PREM)model of Qα~800 and Qβ~312.We propose that the lower mantle beneath Northeast China is relatively colder than the average mantle,resulting in weaker intrinsic attenuation and higher velocity.We estimated the temperature of the lower mantle beneath Northeast China as approximately 300–700 K colder than the global average value.展开更多
Recently,natural van der Waals heterostructures of(MnBi2 Te4)m(Bi2 Te3)n have been theoretically predicted and experimentally shown to host tunable magnetic properties and topologically nontrivial surface states.We sy...Recently,natural van der Waals heterostructures of(MnBi2 Te4)m(Bi2 Te3)n have been theoretically predicted and experimentally shown to host tunable magnetic properties and topologically nontrivial surface states.We systematically investigate both the structural and electronic responses of MnBi2 Te4 and MnBi4 Te7 to external pressure.In addition to the suppression of antiferromagnetic order,MnBi2 Te4 is found to undergo a metalsemiconductor-metal transition upon compression.The resistivity of MnBi4 Te7 changes dramatically under high pressure and a non-monotonic evolution of p(T)is observed.The nontrivial topology is proved to persist before the structural phase transition observed in the high-pressure regime.We find that the bulk and surface states respond differently to pressure,which is consistent with the non-monotonic change of the resistivity.Interestingly,a pressure-induced amorphous state is observed in MnBi2 Te4,while two high-pressure phase transitions are revealed in MnBi4 Te7.Our combined theoretical and experimental research establishes MnBi2 Te4 and MnBi4 Te7 as highly tunable magnetic topological insulators,in which phase transitions and new ground states emerge upon compression.展开更多
Iron-based superconductor family FeX(X=S,Se,Te)has been one of the research foci in physics and material science due to their record-breaking superconducting temperature(FeSe film)and rich physical phenomena.Recently,...Iron-based superconductor family FeX(X=S,Se,Te)has been one of the research foci in physics and material science due to their record-breaking superconducting temperature(FeSe film)and rich physical phenomena.Recently,FeS,the least studied Fe X compound(due to the difficulty in synthesizing high quality macroscopic crystals)attracted much attention because of its puzzling superconducting pairing symmetry.In this work,combining scanning tunneling microscopy and angle resolved photoemission spectroscopy(ARPES)with sub-micron spatial resolution,we investigate the intrinsic electronic structures of superconducting FeS from individual single crystalline domains.Unlike FeTe or FeSe,FeS remains identical tetragonal structure from room temperature down to 5 K,and the band structures observed can be well reproduced by our ab-initio calculations.Remarkably,mixed with the 1×1 tetragonal metallic phase,we also observe the coexistence of √5×√5 reconstructed insulating phase in the crystal,which not only helps explain the unusual properties of FeS,but also demonstrates the importance of using spatially resolved experimental tools in the study of this compound.展开更多
目的研究妊娠中期贫血对新生儿体格发育指标的影响。方法选取2019年1月—2019年10月在本院分娩的单胎无其它并发症及合并症的产妇382例作为研究对象,入院待产时回顾性收集妊娠中期血常规结果,分娩后立即测量新生儿出生体重和身长,并计...目的研究妊娠中期贫血对新生儿体格发育指标的影响。方法选取2019年1月—2019年10月在本院分娩的单胎无其它并发症及合并症的产妇382例作为研究对象,入院待产时回顾性收集妊娠中期血常规结果,分娩后立即测量新生儿出生体重和身长,并计算体质指数。所有数据采用SPSS软件进行统计学分析。结果贫血组孕妇所分娩新生儿的体重(2730.47±183.94 g vs 3366.78±306.98 g)、身长(48.49±1.39 cm vs 50.64±1.37 cm)以及出生孕周(38.56±1.35周vs 39.38±0.98周)均小于对照组(均P<0.05),而两组的体质指数(BMI)无统计学差异(20.99±4.64 kg/m^(2) vs 20.98±4.52 kg/m^(2),P>0.05)。贫血孕妇早产及低体重儿的发生率均高于正常孕妇(均为10.59%vs 0%,P<0.05)。妊娠中期血红蛋白水平与出生体重及身长均存在正相关(r值分别为0.331和0.377,均P<0.05)。结论妊娠中期贫血是早产和低出生体重儿的危险因素,新生儿出生体重和身长与母体血红蛋白浓度存在正相关。展开更多
Ternary transition metal chalcogenides provide a rich platform to search and study intriguing electronic properties. Using angle-resolved photoemission spectroscopy and ab initio calculation, we investigate the electr...Ternary transition metal chalcogenides provide a rich platform to search and study intriguing electronic properties. Using angle-resolved photoemission spectroscopy and ab initio calculation, we investigate the electronic structure of Cu_(2)TlX_(2)(X = Se, Te), ternary transition metal chalcogenides with quasi-two-dimensional crystal structure. The band dispersions near the Fermi level are mainly contributed by the Te/Se p orbitals. According to our ab-initio calculation, the electronic structure changes from a semiconductor with indirect band gap in Cu_(2)TlSe_(2) to a semimetal in Cu_(2)TlTe_(2), suggesting a band-gap tunability with the composition of Se and Te. By comparing ARPES experimental data with the calculated results, we identify strong modulation of the band structure by spin–orbit coupling in the compounds. Our results provide a ternary platform to study and engineer the electronic properties of transition metal chalcogenides related to large spin–orbit coupling.展开更多
As a van der Waals ferromagnet with high Curie temperature,Fe_(5-x)GeTe_(2) has attracted tremendous interests recently.Here,using high-resolution angle-resolved photoemission spectroscopy(ARPES),we systematically inv...As a van der Waals ferromagnet with high Curie temperature,Fe_(5-x)GeTe_(2) has attracted tremendous interests recently.Here,using high-resolution angle-resolved photoemission spectroscopy(ARPES),we systematically investigated the electronic structure of Fe_(5-x)GeTe_(2) crystals and its temperature evolution.Our ARPES measurement reveals two types of band structures from two different terminations with slight kz evolution.Interestingly,across the ferromagnetic transition,we observed the merging of two split bands above the Curie temperature,suggesting the band splitting due to the exchange interaction within the itinerant Stoner model.Our results provide important insights into the electronic and magnetic properties of Fe_(5-x)GeTe_(2) and the understanding of magnetism in a two-dimensional ferromagnetic system.展开更多
As a new type of quantum state of matter hosting low energy relativistic quasiparticles,Weyl semimetals(WSMs)have attracted significant attention for scientific community and potential quantum device applications.In t...As a new type of quantum state of matter hosting low energy relativistic quasiparticles,Weyl semimetals(WSMs)have attracted significant attention for scientific community and potential quantum device applications.In this study,we present a comprehensive investigation of the structural,magnetic,and transport properties of noncentrosymmetric RAl Si(R=Sm,Ce),which have been predicted to be new magnetic WSM candidates.Both samples exhibit nonsaturated magnetoresistance,with about 900%and 80%for Sm Al Si and Ce Al Si,respectively,at temperature of 1.8 K and magnetic field of 9 T.The carrier densities of Sm Al Si and Ce Al Si exhibit remarkable change around magnetic transition temperatures,signifying that the electronic states are sensitive to the magnetic ordering of rare-earth elements.At low temperatures,Sm Al Si reveals prominent Shubnikov–de Haas oscillations associated with the nontrivial Berry phase.High-pressure experiments demonstrate that the magnetic order is robust and survival under high pressure.Our results would yield valuable insights into WSM physics and potentials in applications to next-generation spintronic devices in the RAl Si(R=Sm,Ce)family.展开更多
The formation and development of pollen are among the most critical processes for reproduction and genetic diversity in the life cycle of f lowering plants.The present study found that SlMYB72 was highly expressed in ...The formation and development of pollen are among the most critical processes for reproduction and genetic diversity in the life cycle of f lowering plants.The present study found that SlMYB72 was highly expressed in the pollen and tapetum of tomato f lowers.Downregulation of SlMYB72 led to a decrease in the amounts of seeds due to abnormal pollen development compared with wild-type plants.Downregulation of SlMYB72 delayed tapetum degradation and inhibited autophagy in tomato anther.Overexpression of SlMYB72 led to abnormal pollen development and delayed tapetum degradation.Expression levels of some autophagy-related genes(ATGs)were decreased in SlMYB72 downregulated plants and increased in overexpression plants.SlMYB72 was directly bound to ACCAAC/ACCAAA motif of the SlATG7 promoter and activated its expression.Downregulation of SlATG7 inhibited the autophagy process and tapetum degradation,resulting in abnormal pollen development in tomatoes.These results indicated SlMYB72 affects the tapetum degradation and pollen development by transcriptional activation of SlATG7 and autophagy in tomato anther.The study expands the understanding of the regulation of autophagy by SlMYB72,uncovers the critical role that autophagy plays in pollen development,and provides potential candidate genes for the production of male-sterility in plants.展开更多
A false alarm fault frequently appeared in antenna-servo system of the CINRAD/SA weather radar of Shanwei in the second half of 2011, so possible reasons for the false alarm fault were listed firstly using method of e...A false alarm fault frequently appeared in antenna-servo system of the CINRAD/SA weather radar of Shanwei in the second half of 2011, so possible reasons for the false alarm fault were listed firstly using method of exhaustion, and then the main reason was determined using exclusive method. That is, the fault was closely related to the signal transmission channel from the antenna mount to servo system in RDA cabinet. After ex- amining questionable nodes in the transmission channels of the alarm signal, we found that the false alarm fault might result from the interference of a burr in the temperature sensing circuit of the elevation motor. In actual operation, a filter capacitor was connected with the corresponding pin in the upper optical board to screen the interference of a burr, thereby successfully eliminating the false alarm fault in antenna-servo system of the CIN- RAD/SA radar of Shanwei.展开更多
Nowadays,high penetration of wind power is integrated into power grids,and WTs usually adopt the MPPT algorithm to maximize power output,which decouples the rotor speeds of wind turbines(WTs)and system frequency.There...Nowadays,high penetration of wind power is integrated into power grids,and WTs usually adopt the MPPT algorithm to maximize power output,which decouples the rotor speeds of wind turbines(WTs)and system frequency.Therefore,WTs cannot provide frequency support like conventional generators.To that end,especially avoiding WTs aggravating excessive power generation during over-frequency events,optimal droop control is proposed to reduce power output by fully utilizing WTs’own potential in accelerating rotors.Due to unreliable communication in a wind farm,a game theory-based distributed rotor kinetic energy optimization model is developed to obtain the ideal WT rotor speed and power reduction.Next,the optimal droop gains for WTs are designed to be proportional to their ideal power reduction.Then,not only the frequency support capability of WTs is fully activated,but also as much wind power as possible will be stored as kinetic energy into the accelerated rotor blades.Finally,the effectiveness and rationality of the proposed control are verified in MATLAB and DIgSILENT.展开更多
For islanded microgrids(MGs),distributed control is regarded as a preferred alternative to centralized control for the frequency restoration of MGs.However,distributed control with successive communication restricts t...For islanded microgrids(MGs),distributed control is regarded as a preferred alternative to centralized control for the frequency restoration of MGs.However,distributed control with successive communication restricts the efficiency and resilience of the control system.To address this issue,this paper proposes a distributed event-triggered control strategy for the frequency secondary control in islanded MGs.The proposed event-triggered control is Zeno behavior free and enables each DG to update and propagate its state to neighboring DGs only when a specific“event”occurs,which significantly reduces the communication burden.Compared with the existing event-triggered control,a trigger condition checking period of the proposed event-triggered control is provided to reduce the computation burden when checking the trigger condition.Furthermore,using the aperiodicity and intermittent properties of the communication,a simple detection principle is proposed to detect and isolate the compromised communication links in a timely and economic fashion,which improves the resilience of the system against FDI attacks.Finally,the control effectiveness of the proposed control scheme is validated by the simulation results of the tests on an MG with 4 DGs.展开更多
基金financially supported by National Natural Science Foundation of China (32160801)China Agriculture Research System (CARS-39-12)+1 种基金Young Talent Fund of Association for Science and Technology in Shaanxi, China (2023-6-2-1)“Double-chain” project on livestock breeding (2022GDTSLD-46)
文摘Background Dysregulation of lipid metabolism and its consequences on growth performance in young ruminants have attracted attention,especially in the context of alternative feeding strategies.This study aims to elucidate the effects of milk replacer(MR)feeding on growth,lipid metabolism,colonic epithelial gene expression,colonic microbiota composition and systemic metabolism in goat kids compared to breast milk(BM)feeding,addressing a critical knowledge gap in early life nutrition.Methods Ten female goat kids were divided into 2 groups:those fed breast milk(BM group)and those fed a milk replacer(MR group).Over a period of 28 d,body weight was monitored and blood and tissue samples were collected for biochemical,transcriptomic and metabolomic analyses.Profiling of the colonial microbiota was performed using 16S rRNA gene sequencing.Intestinal microbiota transplantation(IMT)experiments in gnotobiotic mice were per-formed to validate causality.Results MR-fed pups exhibited reduced daily body-weight gain due to impaired lipid metabolism as evidenced by lower serum and liver total cholesterol(TC)and non-esterified fatty acid(NEFA)concentrations.Transcriptomic analysis of the colonic epithelium revealed upregulated genes involved in negative regulation of lipid metabolism,concomitant with microbiota shifts characterized by a decrease in Firmicutes and an increase in Actinobacteria.Specifically,genera such as Bifidobacterium and Prevotella were enriched in the MR group,while Clostridium and Fae-calibacterium were depleted.Metabolomics analyses confirmed alterations in bile acid and fatty acid metabolic path-ways.IMT experiments in mice recapitulated the metabolic phenotype observed in MR-fed goats,confirming the role of the microbiota in modulating host lipid metabolism.Conclusions Milk replacer feeding in goat kids disrupts lipid metabolism and gut microbiota dynamics,result-ing in reduced growth rates and metabolic alterations.These findings highlight the importance of early nutritional intervention on metabolic programming and suggest that modulation of the gut microbiota may be a target for improving growth and metabolic health in ruminants.This study contributes to the understanding of nutritional management strategies in livestock and their impact on animal health and productivity.
基金supported by Hainan Provincial Natural Science Foundation of China(No.524RC532)Research Startup Funding from Hainan Institute of Zhejiang University(No.0210-6602-A12202)Project of Sanya Yazhou Bay Science and Technology City(No.SKJC-2022-PTDX-009/010/011).
文摘Given the rapid development of advanced information systems,microgrids(MGs)suffer from more potential attacks that affect their operational performance.Conventional distributed secondary control with a small,fixed sampling time period inevitably causes the wasteful use of communication resources.This paper proposes a self-triggered secondary control scheme under perturbations from false data injection(FDI)attacks.We designed a linear clock for each DG to trigger its controller at aperiodic and intermittent instants.Sub-sequently,a hash-based defense mechanism(HDM)is designed for detecting and eliminating malicious data infiltrated in the MGs.With the aid of HDM,a self-triggered control scheme achieves the secondary control objectives even in the presence of FDI attacks.Rigorous theoretical analyses and simulation results indicate that the introduced secondary control scheme significantly reduces communication costs and enhances the resilience of MGs under FDI attacks.
基金supported by National Natural Science Foundation of China(Grant No:52477133)Science and Technology Project of China Southern Power Grid(Grant No.GDKJXM20231178(036100KC23110012)+1 种基金GDKJXM20240389(030000KC24040053))Sanya Yazhou Bay Science and Technology City(Grant No:SKJC-JYRC-2024-66).
文摘With the rapid development of large-scale regional interconnected power grids,the risk of cascading failures under extreme condi-tions,such as natural disasters and military strikes,has increased significantly.To enhance the response capability of power systems to extreme events,this study focuses on a method for generator coherency detection.To overcome the shortcomings of the traditional slow coherency method,this paper introduces a novel coherent group identification algorithm based on the theory of nonlinear dynam-ical systems.By analyzing the changing trend of the Euclidean norm of the state variable derivatives in the reduced system,the algorithm can accurately identify the magnitude of the disturbances.Based on the slow coherency methods,the algorithm can correctly recognize coherent generator groups by analyzing system characteristics under varying disturbance magnitudes.This improvement enhances the applicability and accuracy of the coherency detection algorithm under extreme conditions,providing support for emergency control and protection in the power system.Simulations and comparison analyses on IEEE 39-bus system are conducted to validate the accuracy and superiority of the proposed coherent generator group identification method under extreme conditions.
基金Key Laboratory of Modern Power System Simulation and Control&Renewable Energy Technology(Northeast Electric Power University)Open Fund(MPSS2023⁃01)National Natural Science Foundation of China(No.52477133)+2 种基金Hainan Provincial Natural Science Foundation of China(No.524RC532)Research Startup Funding from Hainan Institute of Zhejiang University(No.0210-6602-A12202)Project of Sanya Yazhou Bay Science and Technology City(No.SKJC-2022-PTDX-009/010/011).
文摘Traditional active power sharing in microgrids,achieved by the distributed average consensus,requires each controller to continuously trigger and communicate with each other,which is a wasteful use of the limited computation and communication resources of the secondary controller.To enhance the efficiency of secondary control,we developed a novel distributed self-triggered active power-sharing control strategy by introducing the signum function and a flexible linear clock.Unlike continuous communication–based controllers,the proposed self-triggered distributed controller prompts distributed generators to perform control actions and share information with their neighbors only at specific time instants monitored by the linear clock.Therefore,this approach results in a significant reduction in both the computation and communication requirements.Moreover,this design naturally avoids Zeno behavior.Furthermore,a modified triggering condition was established to achieve further reductions in computation and communication.The simulation results confirmed that the proposed control scheme achieves distributed active power sharing with very few controller triggers,thereby substantially enhancing the efficacy of secondary control in MGs.
文摘The dimensionality of quantum materials strongly affects their physical properties.Although many emergent phenomena,such as charge-density wave and Luttinger liquid behavior,are well understood in one-dimensional(1D)systems,the generalization to explore them in higher dimensional systems is still a challenging task.In this study,we aim to bridge this gap by systematically investigating the crystal and electronic structures of molybdenum-oxide family compounds,where the contexture of 1D chains facilitates rich emergent properties.While the quasi-1D chains in these materials share general similarities,such as the motifs made up of MoO_(6)octahedrons,they exhibit vast complexity and remarkable tunability.We disassemble the 1D chains in molybdenum oxides with different dimensions and construct effective models to excellently fit their low-energy electronic structures obtained by ab initio calculations.Furthermore,we discuss the implications of such chains on other physical properties of the materials and the practical significance of the effective models.Our work establishes the molybdenum oxides as simple and tunable model systems for studying and manipulating the dimensionality in quantum systems.
基金supported by the National Key R&D Program of China(Grant Nos.2022YFA1403100 and 2022YFA1403200)the National Natural Science Foundation of China(Grant Nos.12275148,12004270,and 52272265)+1 种基金Guangdong Basic and Applied Basic Research Foundation(Grant No.2022B1515120020)support from Tsinghua University Initiative Scientific Research Program.
文摘High-temperature superconductivity(HTSC)remains one of the most challenging and fascinating mysteries in condensed matter physics.Recently,superconductivity with transition temperature exceeding liquid-nitrogen temperature is discovered in La_(3)Ni_(2)O_(7) at high pressure,which provides a new platform to explore the unconventional HTSC.In this work,using high-resolution angle-resolved photoemission spectroscopy and ab initio calculation,we systematically investigate the electronic structures of La_(3)Ni_(2)O_(7) at ambient pressure.Our experiments are in nice agreement with ab initio calculations after considering an orbital-dependent band renormalization effect.The strong electron correlation effect pushes a flat band of d_(z^(2))𝑧2 orbital component below the Fermi level(E_(F)),which is predicted to locate right at E_(F) under high pressure.Moreover,the d_(x^(2)−y^(2)) band shows pseudogap-like behavior with suppressed spectral weight and diminished quasiparticle peak near E_(F).Our findings provide important insights into the electronic structure of La_(3)Ni_(2)O_(7),which will shed light on understanding of the unconventional superconductivity in nickelates.
基金supported by the National Natural Science Foundation of China (Grant No. 52272265)the National Key R&D Program of China (Grant Nos. 2023YFA1607400 and 2018YFA0704300)+4 种基金the support from the National Natural Science Foundation of China (Grant Nos. 52271016 and 52188101)the support from Analytical Instrumentation Center (# SPST-AIC10112914), SPST, Shanghai Tech Universitythe European Research Council (ERC Advanced Grant No. 742068 ‘TOPMAT’)the DFG through SFB 1143 (Project ID 247310070)the Würzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter ct.qmat (EXC2147,Project ID 390858490)。
文摘Recently, giant intrinsic anomalous Hall effect(AHE) has been observed in the materials with kagome lattice.Here, we systematically investigate the influence of high pressure on the AHE in the ferromagnet LiMn_(6)Sn_(6) with clean Mn kagome lattice. Our in situ high-pressure Raman spectroscopy indicates that the crystal structure of LiMn_(6)Sn_(6) maintains a hexagonal phase under high pressures up to 8.51 GPa. The anomalous Hall conductivity(AHC) σ_(xy)^(A) remains around 150 Ω^(-1)·cm^(-1), dominated by the intrinsic mechanism. Combined with theoretical calculations, our results indicate that the stable AHE under pressure in Li Mn_(6)Sn_(6) originates from the robust electronic and magnetic structure.
基金Key Education Research Project of Zhaoqing Education Development Research Institute in 2023(ZQJYY2023016)Key Education Research Project of Zhaoqing Education Development Research Institute in 2016(ZQJYY2016003).
文摘Using methods such as questionnaire survey and literature review,a survey was conducted on the professional development of physical education teachers in Huaiji County under the background of the new curriculum standards.The research results found that physical education teachers in Huaiji County have a relatively good distribution structure in terms of teaching experience,age,and education level,but the gender ratio and professional title ratio need to be improved.In terms of professional competence,teachers have shown good performance in teaching implementation ability,but there is still room for improvement in teaching design ability.A certain proportion of teachers still express dissatisfaction with professional title promotion,hardware configuration satisfaction,salary and benefits,and school reward mechanisms.Based on this,this study proposes some measures to improve the professional development level of county-level physical education teachers,such as enhancing teachers teaching design and implementation abilities,strengthening the cultivation of technical action demonstration abilities,improving hardware configuration satisfaction and teaching effectiveness reflection level,strengthening guidance and support for teachers professional development,and enhancing the promotion and implementation of post employment training.
基金supported by funding from the National Natural Science Foundation of China (grant no. 41904061)China Postdoctoral Science Foundation (grant no. 2018M640742)
文摘The thermal structure of the lower mantle plays a key role in understanding the dynamic processes of the Earth's evolution and mantle convection.Because intrinsic attenuation in the lower mantle is highly sensitive to temperature,determining of the attenuation of the lower mantle could help us determine its thermal state.We attempted to constrain the attenuation of the lower mantle by measuring the amplitude ratios of p to ScP on the vertical component and s to ScS on the tangential component at short epicentral distances for seismic wave data from deep earthquakes in Northeast China.We calculated the theoretical amplitude ratios of p to ScP and s to ScS by using ray theory and the axial-symmetric spectral element method AxiSEM,as well as by considering the effects of radiation patterns,geometrical spreading,and ScP reflection coefficients.By comparing the observed amplitude ratios with the synthetic results,we constrained the quality factors as Qα≈3,000 and Qβ≈1,300 in the lower mantle beneath Northeast China,which are much larger than those in the preliminary reference Earth model(PREM)model of Qα~800 and Qβ~312.We propose that the lower mantle beneath Northeast China is relatively colder than the average mantle,resulting in weaker intrinsic attenuation and higher velocity.We estimated the temperature of the lower mantle beneath Northeast China as approximately 300–700 K colder than the global average value.
基金Supported by the National Key Research and Development Program of China under Grant Nos.2018YFA0704300 and2017YFE0131300the National Natural Science Foundation of China under Grant Nos.U1932217,11974246,11874263 and10225417+1 种基金the Natural Science Foundation of Shanghai under Grant No.19ZR1477300the support from Analytical Instrumentation Center(SPST-AIC10112914),SPST,ShanghaiTech Universitysupported by Collaborative Research Project of Materials and Structures Laboratory,Tokyo Institute of Technology,Japan,Part of this research is supported by COMPRES(NSF Cooperative Agreement EAR-1661511)。
文摘Recently,natural van der Waals heterostructures of(MnBi2 Te4)m(Bi2 Te3)n have been theoretically predicted and experimentally shown to host tunable magnetic properties and topologically nontrivial surface states.We systematically investigate both the structural and electronic responses of MnBi2 Te4 and MnBi4 Te7 to external pressure.In addition to the suppression of antiferromagnetic order,MnBi2 Te4 is found to undergo a metalsemiconductor-metal transition upon compression.The resistivity of MnBi4 Te7 changes dramatically under high pressure and a non-monotonic evolution of p(T)is observed.The nontrivial topology is proved to persist before the structural phase transition observed in the high-pressure regime.We find that the bulk and surface states respond differently to pressure,which is consistent with the non-monotonic change of the resistivity.Interestingly,a pressure-induced amorphous state is observed in MnBi2 Te4,while two high-pressure phase transitions are revealed in MnBi4 Te7.Our combined theoretical and experimental research establishes MnBi2 Te4 and MnBi4 Te7 as highly tunable magnetic topological insulators,in which phase transitions and new ground states emerge upon compression.
基金Project supported by CAS-Shanghai Science Research Center,China(Grant No.CAS-SSRC-YH-2015-01)the National Key R&D Program of China(Grant No.2017YFA0305400)+4 种基金the National Natural Science Foundation of China(Grant Nos.11674229,11227902,and 11604207)the EPSRC Platform Grant(Grant No.EP/M020517/1)Hefei Science Center,Chinese Academy of Sciences(Grant No.2015HSC-UE013)Science and Technology Commission of Shanghai Municipality,China(Grant No.14520722100)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB04040200)。
文摘Iron-based superconductor family FeX(X=S,Se,Te)has been one of the research foci in physics and material science due to their record-breaking superconducting temperature(FeSe film)and rich physical phenomena.Recently,FeS,the least studied Fe X compound(due to the difficulty in synthesizing high quality macroscopic crystals)attracted much attention because of its puzzling superconducting pairing symmetry.In this work,combining scanning tunneling microscopy and angle resolved photoemission spectroscopy(ARPES)with sub-micron spatial resolution,we investigate the intrinsic electronic structures of superconducting FeS from individual single crystalline domains.Unlike FeTe or FeSe,FeS remains identical tetragonal structure from room temperature down to 5 K,and the band structures observed can be well reproduced by our ab-initio calculations.Remarkably,mixed with the 1×1 tetragonal metallic phase,we also observe the coexistence of √5×√5 reconstructed insulating phase in the crystal,which not only helps explain the unusual properties of FeS,but also demonstrates the importance of using spatially resolved experimental tools in the study of this compound.
文摘目的研究妊娠中期贫血对新生儿体格发育指标的影响。方法选取2019年1月—2019年10月在本院分娩的单胎无其它并发症及合并症的产妇382例作为研究对象,入院待产时回顾性收集妊娠中期血常规结果,分娩后立即测量新生儿出生体重和身长,并计算体质指数。所有数据采用SPSS软件进行统计学分析。结果贫血组孕妇所分娩新生儿的体重(2730.47±183.94 g vs 3366.78±306.98 g)、身长(48.49±1.39 cm vs 50.64±1.37 cm)以及出生孕周(38.56±1.35周vs 39.38±0.98周)均小于对照组(均P<0.05),而两组的体质指数(BMI)无统计学差异(20.99±4.64 kg/m^(2) vs 20.98±4.52 kg/m^(2),P>0.05)。贫血孕妇早产及低体重儿的发生率均高于正常孕妇(均为10.59%vs 0%,P<0.05)。妊娠中期血红蛋白水平与出生体重及身长均存在正相关(r值分别为0.331和0.377,均P<0.05)。结论妊娠中期贫血是早产和低出生体重儿的危险因素,新生儿出生体重和身长与母体血红蛋白浓度存在正相关。
基金supported by the National Natural Science Foundation of China (Grant No. 11774190)。
文摘Ternary transition metal chalcogenides provide a rich platform to search and study intriguing electronic properties. Using angle-resolved photoemission spectroscopy and ab initio calculation, we investigate the electronic structure of Cu_(2)TlX_(2)(X = Se, Te), ternary transition metal chalcogenides with quasi-two-dimensional crystal structure. The band dispersions near the Fermi level are mainly contributed by the Te/Se p orbitals. According to our ab-initio calculation, the electronic structure changes from a semiconductor with indirect band gap in Cu_(2)TlSe_(2) to a semimetal in Cu_(2)TlTe_(2), suggesting a band-gap tunability with the composition of Se and Te. By comparing ARPES experimental data with the calculated results, we identify strong modulation of the band structure by spin–orbit coupling in the compounds. Our results provide a ternary platform to study and engineer the electronic properties of transition metal chalcogenides related to large spin–orbit coupling.
基金the National Key R&D Program of China(Grant No.2017YFA0305400)。
文摘As a van der Waals ferromagnet with high Curie temperature,Fe_(5-x)GeTe_(2) has attracted tremendous interests recently.Here,using high-resolution angle-resolved photoemission spectroscopy(ARPES),we systematically investigated the electronic structure of Fe_(5-x)GeTe_(2) crystals and its temperature evolution.Our ARPES measurement reveals two types of band structures from two different terminations with slight kz evolution.Interestingly,across the ferromagnetic transition,we observed the merging of two split bands above the Curie temperature,suggesting the band splitting due to the exchange interaction within the itinerant Stoner model.Our results provide important insights into the electronic and magnetic properties of Fe_(5-x)GeTe_(2) and the understanding of magnetism in a two-dimensional ferromagnetic system.
基金supported by the National Key R&D Program of China(Grant Nos.2018YFA0704300 and 2017YFB0503302)the National Natural Science Foundation of China(Grant Nos.U1932217,11974246,12004252,61771234,and 12004251)+6 种基金the Natural Science Foundation of Shanghai(Grant Nos.19ZR1477300 and 20ZR1436100)the Science and Technology Commission of Shanghai Municipality(Grant Nos.19JC1413900 and YDZX20203100001438)the Shanghai Science and Technology Plan(Grant No.21DZ2260400),the Shanghai Sailing Program(Grant No.21YF1429200)the Interdisciplinary Program of Wuhan National High Magnetic Field Center(Grant No.WHMFC202124)the Beijing National Laboratory for Condensed Matter Physicsthe support from Analytical Instrumentation Center(Grant No.SPST-AIC10112914)Centre for High-resolution Electron Microscopy(ChEM)(Grant No.EM02161943),SPST,Shanghai Tech University。
文摘As a new type of quantum state of matter hosting low energy relativistic quasiparticles,Weyl semimetals(WSMs)have attracted significant attention for scientific community and potential quantum device applications.In this study,we present a comprehensive investigation of the structural,magnetic,and transport properties of noncentrosymmetric RAl Si(R=Sm,Ce),which have been predicted to be new magnetic WSM candidates.Both samples exhibit nonsaturated magnetoresistance,with about 900%and 80%for Sm Al Si and Ce Al Si,respectively,at temperature of 1.8 K and magnetic field of 9 T.The carrier densities of Sm Al Si and Ce Al Si exhibit remarkable change around magnetic transition temperatures,signifying that the electronic states are sensitive to the magnetic ordering of rare-earth elements.At low temperatures,Sm Al Si reveals prominent Shubnikov–de Haas oscillations associated with the nontrivial Berry phase.High-pressure experiments demonstrate that the magnetic order is robust and survival under high pressure.Our results would yield valuable insights into WSM physics and potentials in applications to next-generation spintronic devices in the RAl Si(R=Sm,Ce)family.
基金supported by the National Natural Science Foundation of China(32172596)the Technology Innovation and Application Development Project in Chongqing(cstc2021jscxcylhX0115)+3 种基金the Chongqing Talents Innovation Leading Talents Project(cstc2022ycjh-bgzxm0018)the Tianfu Scholar Program of Sichuan Province(Department of Human Resources and Social Security of Sichuan Province 2021-58)d the Fundamental Research Funds for the Central Universities(2021CDJZYJH002)The Graduate Research and Innovation Foundation of Chongqing,China(CYB22048).
文摘The formation and development of pollen are among the most critical processes for reproduction and genetic diversity in the life cycle of f lowering plants.The present study found that SlMYB72 was highly expressed in the pollen and tapetum of tomato f lowers.Downregulation of SlMYB72 led to a decrease in the amounts of seeds due to abnormal pollen development compared with wild-type plants.Downregulation of SlMYB72 delayed tapetum degradation and inhibited autophagy in tomato anther.Overexpression of SlMYB72 led to abnormal pollen development and delayed tapetum degradation.Expression levels of some autophagy-related genes(ATGs)were decreased in SlMYB72 downregulated plants and increased in overexpression plants.SlMYB72 was directly bound to ACCAAC/ACCAAA motif of the SlATG7 promoter and activated its expression.Downregulation of SlATG7 inhibited the autophagy process and tapetum degradation,resulting in abnormal pollen development in tomatoes.These results indicated SlMYB72 affects the tapetum degradation and pollen development by transcriptional activation of SlATG7 and autophagy in tomato anther.The study expands the understanding of the regulation of autophagy by SlMYB72,uncovers the critical role that autophagy plays in pollen development,and provides potential candidate genes for the production of male-sterility in plants.
文摘A false alarm fault frequently appeared in antenna-servo system of the CINRAD/SA weather radar of Shanwei in the second half of 2011, so possible reasons for the false alarm fault were listed firstly using method of exhaustion, and then the main reason was determined using exclusive method. That is, the fault was closely related to the signal transmission channel from the antenna mount to servo system in RDA cabinet. After ex- amining questionable nodes in the transmission channels of the alarm signal, we found that the false alarm fault might result from the interference of a burr in the temperature sensing circuit of the elevation motor. In actual operation, a filter capacitor was connected with the corresponding pin in the upper optical board to screen the interference of a burr, thereby successfully eliminating the false alarm fault in antenna-servo system of the CIN- RAD/SA radar of Shanwei.
基金supported by National Key R&D Program of China(Basic Research Class)(No.2017YFB0903000)National Natural Science Foundation of China(No.U1909201)。
文摘Nowadays,high penetration of wind power is integrated into power grids,and WTs usually adopt the MPPT algorithm to maximize power output,which decouples the rotor speeds of wind turbines(WTs)and system frequency.Therefore,WTs cannot provide frequency support like conventional generators.To that end,especially avoiding WTs aggravating excessive power generation during over-frequency events,optimal droop control is proposed to reduce power output by fully utilizing WTs’own potential in accelerating rotors.Due to unreliable communication in a wind farm,a game theory-based distributed rotor kinetic energy optimization model is developed to obtain the ideal WT rotor speed and power reduction.Next,the optimal droop gains for WTs are designed to be proportional to their ideal power reduction.Then,not only the frequency support capability of WTs is fully activated,but also as much wind power as possible will be stored as kinetic energy into the accelerated rotor blades.Finally,the effectiveness and rationality of the proposed control are verified in MATLAB and DIgSILENT.
基金supported by the National Key Research and Development Program of China(Basic Research Class)(2017YFB0903000)the National Natural Science Foundation of China(U1909201).
文摘For islanded microgrids(MGs),distributed control is regarded as a preferred alternative to centralized control for the frequency restoration of MGs.However,distributed control with successive communication restricts the efficiency and resilience of the control system.To address this issue,this paper proposes a distributed event-triggered control strategy for the frequency secondary control in islanded MGs.The proposed event-triggered control is Zeno behavior free and enables each DG to update and propagate its state to neighboring DGs only when a specific“event”occurs,which significantly reduces the communication burden.Compared with the existing event-triggered control,a trigger condition checking period of the proposed event-triggered control is provided to reduce the computation burden when checking the trigger condition.Furthermore,using the aperiodicity and intermittent properties of the communication,a simple detection principle is proposed to detect and isolate the compromised communication links in a timely and economic fashion,which improves the resilience of the system against FDI attacks.Finally,the control effectiveness of the proposed control scheme is validated by the simulation results of the tests on an MG with 4 DGs.
