The smart grid utilizes the demand side management technology to motivate energy users towards cutting demand during peak power consumption periods, which greatly improves the operation efficiency of the power grid. H...The smart grid utilizes the demand side management technology to motivate energy users towards cutting demand during peak power consumption periods, which greatly improves the operation efficiency of the power grid. However, as the number of energy users participating in the smart grid continues to increase, the demand side management strategy of individual agent is greatly affected by the dynamic strategies of other agents. In addition, the existing demand side management methods, which need to obtain users’ power consumption information,seriously threaten the users’ privacy. To address the dynamic issue in the multi-microgrid demand side management model, a novel multi-agent reinforcement learning method based on centralized training and decentralized execution paradigm is presented to mitigate the damage of training performance caused by the instability of training experience. In order to protect users’ privacy, we design a neural network with fixed parameters as the encryptor to transform the users’ energy consumption information from low-dimensional to high-dimensional and theoretically prove that the proposed encryptor-based privacy preserving method will not affect the convergence property of the reinforcement learning algorithm. We verify the effectiveness of the proposed demand side management scheme with the real-world energy consumption data of Xi’an, Shaanxi, China. Simulation results show that the proposed method can effectively improve users’ satisfaction while reducing the bill payment compared with traditional reinforcement learning(RL) methods(i.e., deep Q learning(DQN), deep deterministic policy gradient(DDPG),QMIX and multi-agent deep deterministic policy gradient(MADDPG)). The results also demonstrate that the proposed privacy protection scheme can effectively protect users’ privacy while ensuring the performance of the algorithm.展开更多
Laser-induced plasmas of dual-pulse fiber-optic laser-induced breakdown spectroscopy with different pulse energy ratios are studied by using the optical emission spectroscopy(OES)and fast imaging.The energy of the two...Laser-induced plasmas of dual-pulse fiber-optic laser-induced breakdown spectroscopy with different pulse energy ratios are studied by using the optical emission spectroscopy(OES)and fast imaging.The energy of the two laser pulses is independently adjusted within 0–30 m J with the total energy fixed at 30 m J.The inter-pulse delay remains 450 ns constantly.As the energy share of the first pulse increases,a similar bimodal variation trend of line intensities is observed.The two peaks are obtained at the point where the first pulse is half or twice of the second one,and the maximum spectral enhancement is at the first peak.The bimodal variation trend is induced by the change in the dominated mechanism of dual-pulse excitation with the trough between the two peaks caused by the weak coupling between the two mechanisms.By increasing the first pulse energy,there is a transition from the ablation enhancement dominance near the first peak to the plasma reheating dominance near the second peak.The calculations of plasma temperature and electron number density are consistent with the bimodal trend,which have the values of 17024.47 K,2.75×10^(17)cm;and 12215.93 K,1.17×10^(17)cm;at a time delay of 550 ns.In addition,the difference between the two peaks decreases with time delay.With the increase in the first pulse energy share,the plasma morphology undergoes a transformation from hemispherical to shiny-dot and to oblate-cylinder structure during the second laser irradiation from the recorded images by using an intensified charge-coupled device(ICCD)camera.Correspondingly,the peak expansion distance of the plasma front first decreases significantly from 1.99 mm in the single-pulse case to 1.34 mm at 12/18(dominated by ablation enhancement)and then increases slightly with increasing the plasma reheating effect.The variations in plasma dynamics verify that the change of pulse energy ratios leads to a transformation in the dual-pulse excitation mechanism.展开更多
Compared with first-order surface-related multiples from marine data,the onshore internal multiples are weaker and are always combined with a hazy and occasionally strong interference pattern.It is usually difficult t...Compared with first-order surface-related multiples from marine data,the onshore internal multiples are weaker and are always combined with a hazy and occasionally strong interference pattern.It is usually difficult to discriminate these events from complex targets and highly scattering overburdens,especially when the primary energy from deep layers is weaker than that from shallow layers.The internal multiple elimination is even more challenging due to the fact that the velocity and energy difference between primary reflections and internal multiples is tiny.In this study,we propose an improved method which formulates the elimination of the internal multiples as an optimization problem and develops a convolution factor T.The generated internal multiples at all interfaces are obtained using the convolution factor T through iterative inversion of the initial multiple model.The predicted internal multiples are removed from seismic data through subtraction.Finally,several synthetic experiments are conducted to validate the effectiveness of our approach.The results of our study indicate that compared with the traditional virtual events method,the improved method simplifies the multiple prediction process in which internal multiples generated from each interface are built through iterative inversion,thus reducing the calculation cost,improving the accuracy,and enhancing the adaptability of field data.展开更多
For constrained linear parameter varying(LPV)systems,this survey comprehensively reviews the literatures on output feedback robust model predictive control(OFRMPC)over the past two decades from the aspects on motivati...For constrained linear parameter varying(LPV)systems,this survey comprehensively reviews the literatures on output feedback robust model predictive control(OFRMPC)over the past two decades from the aspects on motivations,main contributions,and the related techniques.According to the types of state observer systems and scheduling parameters of LPV systems,different kinds of OFRMPC approaches are summarized and compared.The extensions of OFRMPC for LPV systems to other related uncertain systems are also investigated.The methods of dealing with system uncertainties and constraints in different kinds of OFRMPC optimizations are given.Key issues on OFRMPC optimizations for LPV systems are discussed.Furthermore,the future research directions on OFRMPC for LPV systems are suggested.展开更多
Both the modeling and the load regulation capacity prediction of a supercritical power plant are investigated in this paper. Firstly, an indirect identification method based on subspace identification method is propos...Both the modeling and the load regulation capacity prediction of a supercritical power plant are investigated in this paper. Firstly, an indirect identification method based on subspace identification method is proposed. The obtained identification model is verified by the actual operation data and the dynamic characteristics of the system are well reproduced. Secondly, the model is used to predict the load regulation capacity of thermal power unit. The power, main steam pressure, main steam temperature and other parameters are simulated respectively when the unit load is going up and down. Under the actual constraints, the load regulation capacity of thermal power unit can be predicted quickly.展开更多
A series of high-k[(Na_(0.5)Bi_(0.5))_(x)Bi_(1-x)](W_(x)V_(1-x))O_(4)(abbreviated as NBWV(x value))solid solution ceramics with a scheelite-like structure are synthesized by a modified solid-state reaction method at t...A series of high-k[(Na_(0.5)Bi_(0.5))_(x)Bi_(1-x)](W_(x)V_(1-x))O_(4)(abbreviated as NBWV(x value))solid solution ceramics with a scheelite-like structure are synthesized by a modified solid-state reaction method at the temperature range of 680-760 C.A monoclinic(0≤x<0.09)to tetragonal scheelite(0.09≤x≤1.0)structural phase transition is confirmed by X-ray difraction(XRD),Raman,and infrared(IR)analyses.The effect of structural deformation and order-disorder caused by Na^(+)/Bi^(3+)/W^(6+) complex substitution on microwave dielectric properties is investigated in deail.The compositional series possess a wide range of variable relative permittivity(er=24.8-80)and temperature coefficient of resonant frequency(TCF value,-271.9-188.9 ppm/℃).The maximum permittivity of 80 and a high Qxf value of~10,000 GHz are obtained near the phase boundary at x=0.09.Furthermore,the temperature-stable dielectric ceramics sintered at 680 C with excellent microwave dielectric properties of ε_(r)=80.7,Qxf=9400 GHz(at 4.1 GHz),and TCF value=-3.8 ppm/℃ are designed by mixing the components of x=0.07 and 0.08.In summary,similar sinterability and structural compatibility of scheelite-like solid solution systems make it potential for low-temperature co-fired ceramic(LTCC)applications.展开更多
Micro-LEDs are one of the most promising candidates for next-generation displays,yet they are inconvenienced by the efficiency reduction induced by the sidewall defects when pursuing further scaled-down device dimensi...Micro-LEDs are one of the most promising candidates for next-generation displays,yet they are inconvenienced by the efficiency reduction induced by the sidewall defects when pursuing further scaled-down device dimensions.We have systematically investigated both the size and temporal dependence of micro-LEDs.Micro-LED arrays with a mesa size ranging from 7 to 100μm were prepared for display purposes.The luminance and external quantum efficiency(EQE)were measured and discussed.Surprisingly,micro-LED arrays with a smaller mesa size exhibit a higher EQE under 100 ns pulse duration operation when compared with longer pulse duration operations.Under certain short-pulsed excitation,a 7×7μm^(2)micro-LED array even exhibits a>20%higher EQE as compared to the direct current(DC)or the long duration pulse operation condition.We thus concluded that the notorious efficiency reduction induced by sidewall defects in small-sized micro-LED arrays could be significantly reduced by applying short-pulse voltages.展开更多
Fully homomorphic encryption is faced with two problems now.One is candidate fully homomorphic encryption schemes are few.Another is that the efficiency of fully homomorphic encryption is a big question.In this paper,...Fully homomorphic encryption is faced with two problems now.One is candidate fully homomorphic encryption schemes are few.Another is that the efficiency of fully homomorphic encryption is a big question.In this paper,we propose a fully homomorphic encryption scheme based on LWE,which has better key size.Our main contributions are:(1) According to the binary-LWE recently,we choose secret key from binary set and modify the basic encryption scheme proposed in Linder and Peikert in 2010.We propose a fully homomorphic encryption scheme based on the new basic encryption scheme.We analyze the correctness and give the proof of the security of our scheme.The public key,evaluation keys and tensored ciphertext have better size in our scheme.(2) Estimating parameters for fully homomorphic encryption scheme is an important work.We estimate the concert parameters for our scheme.We compare these parameters between our scheme and Bra 12 scheme.Our scheme have public key and private key that smaller by a factor of about logq than in Bra12 scheme.Tensored ciphertext in our scheme is smaller by a factor of about log2 q than in Bra 12 scheme.Key switching matrix in our scheme is smaller by a factor of about log3 q than in Bra 12 scheme.展开更多
Microsatellite instability(MSI)is a key biomarker for cancer therapy and prognosis.Traditional experimental assays are laborious and time-consuming,and next-generation sequencingbased computational methods do not work...Microsatellite instability(MSI)is a key biomarker for cancer therapy and prognosis.Traditional experimental assays are laborious and time-consuming,and next-generation sequencingbased computational methods do not work on leukemia samples,paraffin-embedded samples,or patient-derived xenografts/organoids,due to the requirement of matched normal samples.Herein,we developed MSIsensor-pro,an open-source single sample MSI scoring method for research and clinical applications.MSIsensor-pro introduces a multinomial distribution model to quantify polymerase slippages for each tumor sample and a discriminative site selection method to enable MSI detection without matched normal samples.We demonstrate that MSIsensor-pro is an ultrafast,accurate,and robust MSI calling method.Using samples with various sequencing depths and tumor purities,MSIsensor-pro significantly outperformed the current leading methods in both accuracy and computational cost.MSIsensor-pro is available at https://github.com/xjtu-omics/msisensor-pro and free for non-commercial use,while a commercial license is provided upon request.展开更多
With the advent of deep learning,self-driving schemes based on deep learning are becoming more and more popular.Robust perception-action models should learn from data with different scenarios and real behaviors,while ...With the advent of deep learning,self-driving schemes based on deep learning are becoming more and more popular.Robust perception-action models should learn from data with different scenarios and real behaviors,while current end-to-end model learning is generally limited to training of massive data,innovation of deep network architecture,and learning in-situ model in a simulation environment.Therefore,we introduce a new image style transfer method into data augmentation,and improve the diversity of limited data by changing the texture,contrast ratio and color of the image,and then it is extended to the scenarios that the model has been unobserved before.Inspired by rapid style transfer and artistic style neural algorithms,we propose an arbitrary style generation network architecture,including style transfer network,style learning network,style loss network and multivariate Gaussian distribution function.The style embedding vector is randomly sampled from the multivariate Gaussian distribution and linearly interpolated with the embedded vector predicted by the input image on the style learning network,which provides a set of normalization constants for the style transfer network,and finally realizes the diversity of the image style.In order to verify the effectiveness of the method,image classification and simulation experiments were performed separately.Finally,we built a small-sized smart car experiment platform,and apply the data augmentation technology based on image style transfer drive to the experiment of automatic driving for the first time.The experimental results show that:(1)The proposed scheme can improve the prediction accuracy of the end-to-end model and reduce the model’s error accumulation;(2)the method based on image style transfer provides a new scheme for data augmentation technology,and also provides a solution for the high cost that many deep models rely heavily on a large number of label data.展开更多
Optical skyrmions formed by photonic spin–orbit(SO)coupling are of significant interest in high-dimensional optical information processing.We report the formation mechanism and non-Hermitian properties of skyrmionlik...Optical skyrmions formed by photonic spin–orbit(SO)coupling are of significant interest in high-dimensional optical information processing.We report the formation mechanism and non-Hermitian properties of skyrmionlike states in a circular confinement potential with photonic SO coupling,which is preferably realized in a concave-planar microcavity system.We show that the effective photonic gauge field leads to two split manifolds of degenerate skyrmions whose spin textures can be controlled via the non-Hermitian properties by introducing circularly polarized gain and loss,exhibiting dramatically discrepant evolutions at the two sides of the exceptional point(EP).Furthermore,the lifetime degeneracy can be lifted by spatially inhomogeneous pumping according to the non-Hermitian mechanism,enabling the possibility for the skyrmion laser.By introducing shape asymmetry of the confinement potential,a double EP evolution can be achieved,which allows non-Hermitian control of the SO coupled states with higher degrees of freedom.These results open the way for the non-Hermitian control of photonic spin in confined systems,which would be of great significance for the fundamentals of advanced optical information processing.展开更多
Recently,piezoelectric/triboelectric nanogenerators based on piezoelectric composite materials have been intensively studied to achieve high electrical output perfomiance.In this work,flexible BaTiO_(3)(BT)/PDMS nanoc...Recently,piezoelectric/triboelectric nanogenerators based on piezoelectric composite materials have been intensively studied to achieve high electrical output perfomiance.In this work,flexible BaTiO_(3)(BT)/PDMS nanocomposite films with various sizes and concentrations were fabricated and used as the nanogenerators.The influence of dielectric properties on the electrical output of nanogenerators was studied as well as the structure of the composites.The dielectric constant increased from 6.5 to 8 with the concentration of BT nanoparticles and decreased with the frequency from 10^(2) to 10^(6) Hz.Furthermore,the dielectric constant showed 11% decrease with the temperature range from 30 to 180℃.It was found that the concentration of BT nanoparticles has promoted the electrical output of nanogenerators.The output voltage and current are all enhanced with the BT nanoparticles,which reached 200 V and 0.24μA in TENG with 40 wt% BT nanoparticles,respectively.The selected device exhibited the power of 0.16 mW and employed to demonstrate its ability to power wearable/portable electronics by lighting the LEDs.展开更多
In this work,we report the dielectric and ferroelectric properties of CuO-doped(1-x)[0.5573Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.4427PbTiO_(3)]-xBa(Zn_(1/3)Nb_(2/3))_(3)(PMNT-xBZN)relaxor ferrielectric ceramic samples with x=0....In this work,we report the dielectric and ferroelectric properties of CuO-doped(1-x)[0.5573Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.4427PbTiO_(3)]-xBa(Zn_(1/3)Nb_(2/3))_(3)(PMNT-xBZN)relaxor ferrielectric ceramic samples with x=0.1725,0.1925,02125 and 0.2325,which were fabricated by a conventional solid-state reaction method.By introducing the CuO into PMNT-xBZN,the sintering temperature of this system is drastically lowered from 1280℃to 1120℃.The second pyrochlore phase,which is often generated during sintering at high temperature,is also inhibited.Meanwhile,broad dielectric peaks with strong dielectric relaxation characteristics are observed from150℃to 100℃.Slim and slanted P-E hysteresis loops and purely electrostrictive strains with V-shape are obtained simultaneously in studied compositions from 30℃to 150℃.These results suggest that CuO could effectively lower the sintering temperature while maintaining the dielectric and ferroelectric properties of PMNT-xBZN relaxor ferroelectric ceramics.展开更多
The luminescence modulation behaviour under the in-situ electric field of rare-earth doped KSr_(2)Nb_(5)O_(15) ceramics opened a new door for the development of dielectric materials.Where the understanding the effect ...The luminescence modulation behaviour under the in-situ electric field of rare-earth doped KSr_(2)Nb_(5)O_(15) ceramics opened a new door for the development of dielectric materials.Where the understanding the effect of rare-earth doping on the electric properties of host,especially at the similar doping concentration with luminescence researches(low concentrations)is very important for the exploration of mechanism of electric-luminescent coupling effect.In this work,Nd^(3+)-doped KSr_(2)Nb_(5)O_(15)(KSN-xNd)ceramics were synthesized,and the electric properties were investigated systematically.Our results suggest that the Nd^(3+) doping slightly increased the phase transition temperatures and improved the piezoelectric response of KSr_(2)Nb_(5)O_(15).Most importantly,a bidirectional dielectric tunability is revealed in KSr_(2)Nb_(5)O_(15).The dielectric permittivity can be adjusted by the DC electric bias,with tunability ranging from12.3% to 21.9%.The related mechanism and relationship between the bidirectional dielectric tunability and ferroelectricity are revealed by temperature-dependent dielectric and ferroelectric characterization.The researches of electric properties and bidirectional dielectric tunability of KSN-based ceramics paved the way to further exploration of electric-luminescent coupling mechanism.展开更多
Cassidy et al.of Trinity College in Dublin,Ireland,studied the social structure of farming communities,focusing on the ancient nobles buried in passage tombs(a channel-style megalithic tomb structure in Europe).Newgra...Cassidy et al.of Trinity College in Dublin,Ireland,studied the social structure of farming communities,focusing on the ancient nobles buried in passage tombs(a channel-style megalithic tomb structure in Europe).Newgrange,built by complex engineering technology,is the most famous stone tunnel tomb in Ireland and one of the most famous prehistoric cemeteries in the country.The tomb is at the end of a stone-lined passage,with an opening like a window above the mausoleum entrance.On the shortest day of the year(winter solstice),this opening allows sunlight to enter the tomb.Researchers conducted DNA analysis of ancient human remains found in the tomb,revealing a rare and unexpected incident of incest.A man buried in Newgrange's tomb about 5000 years ago was the offspring of an incestuous marriage:his parents were either siblings or parents and children.This discovery led the researchers to speculate that the nobles associated with this magnificent tomb may have maintained their bloodlines through incest.展开更多
There are significant differences in the extent of impurity incorporation on different crystallographic directions of GaN microstructures,and the impurity-related deep energy level behavior will have a significant imp...There are significant differences in the extent of impurity incorporation on different crystallographic directions of GaN microstructures,and the impurity-related deep energy level behavior will have a significant impact on device performance.However,a comprehensive understanding of the effect of lateral growth on device performance has not been achieved due to the lack of comprehensive spatial distribution characterization of the optical behavior and impurity incorporation in GaN microstructures.We present a comprehensive study of the optical behavior and growth mechanism of self-assembled GaN microdisks using nanoscale spatially resolved cathodoluminescence(CL)mapping.We have found a clear growth orientation-dependent optical behavior of the lateral and vertical growth sectors of self-assembled GaN microcrystals.The lateral growth sector,i.e.,the{101¯1}-growth sector,forms six side facets of the microdisk and shows significant near-bandgap emission(NBE)and weak deep energy level luminescence.Cavity effect enhanced emission was found for the first time in such a truncated hexagonal Na-flux GaN microdisk system with an ultra-smooth surface(Ra<0.7 nm)and low stress.The self-assembled microdisk shows significant ultraviolet(UV)lasing action(main lasing peak wavelength 370.9 nm,quality factor 1278,threshold 6×10^(4)μJ/cm^(2))under pulsed optical pumping.We believe that the appearance of UV lasing action may be related to the light limitation on the six side facets of the lateral growth of the GaN microdisk,the high structural quality,the low content of deep energy level defects,the low surface roughness,and the low stress.展开更多
In this study,we theoretically proposed a method to achieve an electromagnetically induced transparency(EIT)-like effect in a whispering gallery mode resonator(WGMR)and experimentally validated the method in a lithium...In this study,we theoretically proposed a method to achieve an electromagnetically induced transparency(EIT)-like effect in a whispering gallery mode resonator(WGMR)and experimentally validated the method in a lithium niobate(LN)device.Benefitting from the electro-optic and inverse piezoelectric effects of the LN material,two modes of the LN WGMR that are close in frequency can be tuned at different tuning rates,resulting in EIT-like resonance lineshapes.By varying the electric field applied to the LN WGMR,the full dynamic of the EIT-like phenomenon can be precisely controlled.The experimental results agreed well with the calculations based on the coupled mode theory.Moreover,we observed a hysteresis resulting from the photorefractive effect of LN.We believe our proposed method and demonstrated devices offer a way to control an EIT-like effect,which could have potential applications in light storage,quantum information processing,and enhanced sensing techniques.展开更多
Arabidopsis thaliana is an important and long-established model species for plant molecular biology,genetics,epigenetics,and genomics.However,the latest version of reference genome still contains a significant number ...Arabidopsis thaliana is an important and long-established model species for plant molecular biology,genetics,epigenetics,and genomics.However,the latest version of reference genome still contains a significant number of missing segments.Here,we reported a high-quality and almost complete Col-0 genome assembly with two gaps(named Col-XJTU)by combining the Oxford Nanopore Technologies ultra-long reads,Pacific Biosciences high-fidelity long reads,and Hi-C data.The total genome assembly size is 133,725,193 bp,introducing 14.6 Mb of novel sequences compared to the TAIR10.1 reference genome.All five chromosomes of the Col-XJTU assembly are highly accurate with consensus quality(QV)scores>60(ranging from 62 to 68),which are higher than those of the TAIR10.1 reference(ranging from 45 to 52).We completely resolved chromosome(Chr)3 and Chr5 in a telomere-to-telomere manner.Chr4 was completely resolved except the nucleolar organizing regions,which comprise long repetitive DNA fragments.The Chrl centromere(CEN1),reportedly around 9 Mb in length,is particularly challenging to assemble due to the presence of tens of thousands of CEN180 satellite repeats.Using the cutting-edge sequencing data and novel computational approaches,we assembled a 3.8-Mb-long CEN1 and a 3.5-Mb-long CEN2.We also investigated the structure and epigenetics of centromeres.Four clusters of CEN180 monomers were detected,and the centromere-specific histone H3-like protein(CENH3)exhibited a strong preference for CEN180 Cluster 3.Moreover,we observed hypomethylation patterns in CENH3-enriched regions.We believe that this high-quality genome assembly,Col-XJTU,would serve as a valuable reference to better understand the global pattern of centromeric polymorphisms,as well as the genetic and epigenetic features in plants.展开更多
As a typical representative of the so-called cyber-physical system,smart grid reveals its high efficiency,robustness and reliability compared with conventional power grid.However,due to the deep integration of electri...As a typical representative of the so-called cyber-physical system,smart grid reveals its high efficiency,robustness and reliability compared with conventional power grid.However,due to the deep integration of electrical components and computinginformation in cyber space,smart grid is vulnerable to malicious attacks,especially for a type of attacks named false data injection attacks(FDIAs).FDIAs are capable of tampering meter measurements and affecting the results of state estimation stealthily,which severely threat the security of smart grid.Due to the significantinfluence of FDIAs on smart grid,the research related to FDIAs has received considerable attention over the past decade.This paper aims to summarize recent advances in FDIAs against smart grid state estimation,especially from the aspects of background materials,construction methods,detection and defense strategies.Moreover,future research directions are discussed and outlined by analyzing existing results.It is expected that through the review of FDIAs,the vulnerabilities of smart grid to malicious attacks can be further revealed and more attention can be devoted to the detection and defense of cyber-physical attacks against smart grid.展开更多
In the present work,the nature of phase evolution of(1x)(Na_(0.5)Bi_(0.5))TiO_(3)-xSrTiO_(3)(NBT-xST)solid solutions with x of 0e0.6 is revealed by characterizing the dielectric and ferroelectric properties.Two uniqu...In the present work,the nature of phase evolution of(1x)(Na_(0.5)Bi_(0.5))TiO_(3)-xSrTiO_(3)(NBT-xST)solid solutions with x of 0e0.6 is revealed by characterizing the dielectric and ferroelectric properties.Two unique dielectric anomalies associated with high-temperature nanoregions(PNRs)in the ergodic relaxor(ER)state and low-temperature PNRs in the nonergodic relaxor(NR)state are identified.Characteristic temperatures,including TB,TRT*,Tm,Td and TT*,are determined in fresh and poled states on the basis of the characteristics of the evolution of these two dielectric anomalies.The whole evolution of the transition from the NR state to the ER state is reflected by the temperature-dependent polarization versus electric field(P-E)hysteresis loops,i.e.,from the square loops,via the double-like loops,to the slim loops.The characteristic temperatures,including TP-N,TN-R and TR-dis,are determined by the characteristics of the evolution of P-E loops.Accordingly,a phase diagram of NBT-xST was constructed according to these characteristic temperatures.Most importantly,the relationship between polarization responses and heterogeneous polar phase coexistence has been established and a schematic diagram is given.This work will help to understand the phase evolution and its impact on the macroscopic properties of NBT and the associated NBT-based solid solutions.展开更多
基金supported in part by the National Science Foundation of China (61973247, 61673315, 62173268)the Key Research and Development Program of Shaanxi (2022GY-033)+2 种基金the Nationa Postdoctoral Innovative Talents Support Program of China (BX20200272)the Key Program of the National Natural Science Foundation of China (61833015)the Fundamental Research Funds for the Central Universities (xzy022021050)。
文摘The smart grid utilizes the demand side management technology to motivate energy users towards cutting demand during peak power consumption periods, which greatly improves the operation efficiency of the power grid. However, as the number of energy users participating in the smart grid continues to increase, the demand side management strategy of individual agent is greatly affected by the dynamic strategies of other agents. In addition, the existing demand side management methods, which need to obtain users’ power consumption information,seriously threaten the users’ privacy. To address the dynamic issue in the multi-microgrid demand side management model, a novel multi-agent reinforcement learning method based on centralized training and decentralized execution paradigm is presented to mitigate the damage of training performance caused by the instability of training experience. In order to protect users’ privacy, we design a neural network with fixed parameters as the encryptor to transform the users’ energy consumption information from low-dimensional to high-dimensional and theoretically prove that the proposed encryptor-based privacy preserving method will not affect the convergence property of the reinforcement learning algorithm. We verify the effectiveness of the proposed demand side management scheme with the real-world energy consumption data of Xi’an, Shaanxi, China. Simulation results show that the proposed method can effectively improve users’ satisfaction while reducing the bill payment compared with traditional reinforcement learning(RL) methods(i.e., deep Q learning(DQN), deep deterministic policy gradient(DDPG),QMIX and multi-agent deep deterministic policy gradient(MADDPG)). The results also demonstrate that the proposed privacy protection scheme can effectively protect users’ privacy while ensuring the performance of the algorithm.
基金the Foundation Research Project of Jiangsu Province,China(the Natural Science Fund No.BK20190187)。
文摘Laser-induced plasmas of dual-pulse fiber-optic laser-induced breakdown spectroscopy with different pulse energy ratios are studied by using the optical emission spectroscopy(OES)and fast imaging.The energy of the two laser pulses is independently adjusted within 0–30 m J with the total energy fixed at 30 m J.The inter-pulse delay remains 450 ns constantly.As the energy share of the first pulse increases,a similar bimodal variation trend of line intensities is observed.The two peaks are obtained at the point where the first pulse is half or twice of the second one,and the maximum spectral enhancement is at the first peak.The bimodal variation trend is induced by the change in the dominated mechanism of dual-pulse excitation with the trough between the two peaks caused by the weak coupling between the two mechanisms.By increasing the first pulse energy,there is a transition from the ablation enhancement dominance near the first peak to the plasma reheating dominance near the second peak.The calculations of plasma temperature and electron number density are consistent with the bimodal trend,which have the values of 17024.47 K,2.75×10^(17)cm;and 12215.93 K,1.17×10^(17)cm;at a time delay of 550 ns.In addition,the difference between the two peaks decreases with time delay.With the increase in the first pulse energy share,the plasma morphology undergoes a transformation from hemispherical to shiny-dot and to oblate-cylinder structure during the second laser irradiation from the recorded images by using an intensified charge-coupled device(ICCD)camera.Correspondingly,the peak expansion distance of the plasma front first decreases significantly from 1.99 mm in the single-pulse case to 1.34 mm at 12/18(dominated by ablation enhancement)and then increases slightly with increasing the plasma reheating effect.The variations in plasma dynamics verify that the change of pulse energy ratios leads to a transformation in the dual-pulse excitation mechanism.
基金the National Natural Science Foundation of China under Grant Nos.41974116 and 41930431Local Universities Reformation and Development Personnel Training Supporting Project from Central Authorities under Grant No.140119001 for supporting this work
文摘Compared with first-order surface-related multiples from marine data,the onshore internal multiples are weaker and are always combined with a hazy and occasionally strong interference pattern.It is usually difficult to discriminate these events from complex targets and highly scattering overburdens,especially when the primary energy from deep layers is weaker than that from shallow layers.The internal multiple elimination is even more challenging due to the fact that the velocity and energy difference between primary reflections and internal multiples is tiny.In this study,we propose an improved method which formulates the elimination of the internal multiples as an optimization problem and develops a convolution factor T.The generated internal multiples at all interfaces are obtained using the convolution factor T through iterative inversion of the initial multiple model.The predicted internal multiples are removed from seismic data through subtraction.Finally,several synthetic experiments are conducted to validate the effectiveness of our approach.The results of our study indicate that compared with the traditional virtual events method,the improved method simplifies the multiple prediction process in which internal multiples generated from each interface are built through iterative inversion,thus reducing the calculation cost,improving the accuracy,and enhancing the adaptability of field data.
基金supported in part by the National Natural Science Foundation of China(62103319,62073053,61773396)。
文摘For constrained linear parameter varying(LPV)systems,this survey comprehensively reviews the literatures on output feedback robust model predictive control(OFRMPC)over the past two decades from the aspects on motivations,main contributions,and the related techniques.According to the types of state observer systems and scheduling parameters of LPV systems,different kinds of OFRMPC approaches are summarized and compared.The extensions of OFRMPC for LPV systems to other related uncertain systems are also investigated.The methods of dealing with system uncertainties and constraints in different kinds of OFRMPC optimizations are given.Key issues on OFRMPC optimizations for LPV systems are discussed.Furthermore,the future research directions on OFRMPC for LPV systems are suggested.
文摘Both the modeling and the load regulation capacity prediction of a supercritical power plant are investigated in this paper. Firstly, an indirect identification method based on subspace identification method is proposed. The obtained identification model is verified by the actual operation data and the dynamic characteristics of the system are well reproduced. Secondly, the model is used to predict the load regulation capacity of thermal power unit. The power, main steam pressure, main steam temperature and other parameters are simulated respectively when the unit load is going up and down. Under the actual constraints, the load regulation capacity of thermal power unit can be predicted quickly.
基金supported by the National Natural Science Foundation of China(Grant Nos.61631166004 and 51902245)Hong Wang acknowledged the support of Shenzhen Science and Technology Program(Nos.KQTD20180411143514543 and JSGGZD20220822095603006)。
文摘A series of high-k[(Na_(0.5)Bi_(0.5))_(x)Bi_(1-x)](W_(x)V_(1-x))O_(4)(abbreviated as NBWV(x value))solid solution ceramics with a scheelite-like structure are synthesized by a modified solid-state reaction method at the temperature range of 680-760 C.A monoclinic(0≤x<0.09)to tetragonal scheelite(0.09≤x≤1.0)structural phase transition is confirmed by X-ray difraction(XRD),Raman,and infrared(IR)analyses.The effect of structural deformation and order-disorder caused by Na^(+)/Bi^(3+)/W^(6+) complex substitution on microwave dielectric properties is investigated in deail.The compositional series possess a wide range of variable relative permittivity(er=24.8-80)and temperature coefficient of resonant frequency(TCF value,-271.9-188.9 ppm/℃).The maximum permittivity of 80 and a high Qxf value of~10,000 GHz are obtained near the phase boundary at x=0.09.Furthermore,the temperature-stable dielectric ceramics sintered at 680 C with excellent microwave dielectric properties of ε_(r)=80.7,Qxf=9400 GHz(at 4.1 GHz),and TCF value=-3.8 ppm/℃ are designed by mixing the components of x=0.07 and 0.08.In summary,similar sinterability and structural compatibility of scheelite-like solid solution systems make it potential for low-temperature co-fired ceramic(LTCC)applications.
基金Fujian Provincial Projects(2021HZ0114,2021J01583,2021L3004)Fujian Science Technology Innovation Laboratory for Optoelectronic Information of China(2020ZZ110,2021ZZ122)National Key Research and Development Program of China(2021YFB3600104)。
文摘Micro-LEDs are one of the most promising candidates for next-generation displays,yet they are inconvenienced by the efficiency reduction induced by the sidewall defects when pursuing further scaled-down device dimensions.We have systematically investigated both the size and temporal dependence of micro-LEDs.Micro-LED arrays with a mesa size ranging from 7 to 100μm were prepared for display purposes.The luminance and external quantum efficiency(EQE)were measured and discussed.Surprisingly,micro-LED arrays with a smaller mesa size exhibit a higher EQE under 100 ns pulse duration operation when compared with longer pulse duration operations.Under certain short-pulsed excitation,a 7×7μm^(2)micro-LED array even exhibits a>20%higher EQE as compared to the direct current(DC)or the long duration pulse operation condition.We thus concluded that the notorious efficiency reduction induced by sidewall defects in small-sized micro-LED arrays could be significantly reduced by applying short-pulse voltages.
基金The first author would like to thank for the Fund of Jiangsu Innovation Program for Graduate Education，the Fundamental Research Funds for the Central Universities,and Ningbo Natural Science Foundation，the Chinese National Scholarship fund,and also appreciate the benefit to this work from projects in science and technique of Ningbo municipal.The third author would like to thank for Ningbo Natural Science Foundation
文摘Fully homomorphic encryption is faced with two problems now.One is candidate fully homomorphic encryption schemes are few.Another is that the efficiency of fully homomorphic encryption is a big question.In this paper,we propose a fully homomorphic encryption scheme based on LWE,which has better key size.Our main contributions are:(1) According to the binary-LWE recently,we choose secret key from binary set and modify the basic encryption scheme proposed in Linder and Peikert in 2010.We propose a fully homomorphic encryption scheme based on the new basic encryption scheme.We analyze the correctness and give the proof of the security of our scheme.The public key,evaluation keys and tensored ciphertext have better size in our scheme.(2) Estimating parameters for fully homomorphic encryption scheme is an important work.We estimate the concert parameters for our scheme.We compare these parameters between our scheme and Bra 12 scheme.Our scheme have public key and private key that smaller by a factor of about logq than in Bra12 scheme.Tensored ciphertext in our scheme is smaller by a factor of about log2 q than in Bra 12 scheme.Key switching matrix in our scheme is smaller by a factor of about log3 q than in Bra 12 scheme.
基金supported by the National Key R&D Program of China(Grant Nos.2018YFC0910400 and 2017YFC0907500)the National Natural Science Foundation of China(Grant Nos.31671372,61702406,31701739,and 31970317)+2 种基金the National Science and Technology Major Project of China(Grant No.2018ZX10302205)the‘‘World-Class Universities and the Characteristic Development Guidance Funds for the Central Universities”the General Financial Grant from the China Postdoctoral Science Foundation(Grant Nos.2017M623178 and 2017M623188)
文摘Microsatellite instability(MSI)is a key biomarker for cancer therapy and prognosis.Traditional experimental assays are laborious and time-consuming,and next-generation sequencingbased computational methods do not work on leukemia samples,paraffin-embedded samples,or patient-derived xenografts/organoids,due to the requirement of matched normal samples.Herein,we developed MSIsensor-pro,an open-source single sample MSI scoring method for research and clinical applications.MSIsensor-pro introduces a multinomial distribution model to quantify polymerase slippages for each tumor sample and a discriminative site selection method to enable MSI detection without matched normal samples.We demonstrate that MSIsensor-pro is an ultrafast,accurate,and robust MSI calling method.Using samples with various sequencing depths and tumor purities,MSIsensor-pro significantly outperformed the current leading methods in both accuracy and computational cost.MSIsensor-pro is available at https://github.com/xjtu-omics/msisensor-pro and free for non-commercial use,while a commercial license is provided upon request.
基金the National Natural Science Foundation of China(51965008)Science and Technology projects of Guizhou[2018]2168Excellent Young Researcher Project of Guizhou[2017]5630.
文摘With the advent of deep learning,self-driving schemes based on deep learning are becoming more and more popular.Robust perception-action models should learn from data with different scenarios and real behaviors,while current end-to-end model learning is generally limited to training of massive data,innovation of deep network architecture,and learning in-situ model in a simulation environment.Therefore,we introduce a new image style transfer method into data augmentation,and improve the diversity of limited data by changing the texture,contrast ratio and color of the image,and then it is extended to the scenarios that the model has been unobserved before.Inspired by rapid style transfer and artistic style neural algorithms,we propose an arbitrary style generation network architecture,including style transfer network,style learning network,style loss network and multivariate Gaussian distribution function.The style embedding vector is randomly sampled from the multivariate Gaussian distribution and linearly interpolated with the embedded vector predicted by the input image on the style learning network,which provides a set of normalization constants for the style transfer network,and finally realizes the diversity of the image style.In order to verify the effectiveness of the method,image classification and simulation experiments were performed separately.Finally,we built a small-sized smart car experiment platform,and apply the data augmentation technology based on image style transfer drive to the experiment of automatic driving for the first time.The experimental results show that:(1)The proposed scheme can improve the prediction accuracy of the end-to-end model and reduce the model’s error accumulation;(2)the method based on image style transfer provides a new scheme for data augmentation technology,and also provides a solution for the high cost that many deep models rely heavily on a large number of label data.
基金National Natural Science Foundation of China(61890961,12074303,11804267,12174302,11904279,62177813)Shaanxi Key Science and Technology Innovation Team(2021TD-56)。
文摘Optical skyrmions formed by photonic spin–orbit(SO)coupling are of significant interest in high-dimensional optical information processing.We report the formation mechanism and non-Hermitian properties of skyrmionlike states in a circular confinement potential with photonic SO coupling,which is preferably realized in a concave-planar microcavity system.We show that the effective photonic gauge field leads to two split manifolds of degenerate skyrmions whose spin textures can be controlled via the non-Hermitian properties by introducing circularly polarized gain and loss,exhibiting dramatically discrepant evolutions at the two sides of the exceptional point(EP).Furthermore,the lifetime degeneracy can be lifted by spatially inhomogeneous pumping according to the non-Hermitian mechanism,enabling the possibility for the skyrmion laser.By introducing shape asymmetry of the confinement potential,a double EP evolution can be achieved,which allows non-Hermitian control of the SO coupled states with higher degrees of freedom.These results open the way for the non-Hermitian control of photonic spin in confined systems,which would be of great significance for the fundamentals of advanced optical information processing.
基金supported by the National Natural Science Foundation of China(Grant No.51972263).
文摘Recently,piezoelectric/triboelectric nanogenerators based on piezoelectric composite materials have been intensively studied to achieve high electrical output perfomiance.In this work,flexible BaTiO_(3)(BT)/PDMS nanocomposite films with various sizes and concentrations were fabricated and used as the nanogenerators.The influence of dielectric properties on the electrical output of nanogenerators was studied as well as the structure of the composites.The dielectric constant increased from 6.5 to 8 with the concentration of BT nanoparticles and decreased with the frequency from 10^(2) to 10^(6) Hz.Furthermore,the dielectric constant showed 11% decrease with the temperature range from 30 to 180℃.It was found that the concentration of BT nanoparticles has promoted the electrical output of nanogenerators.The output voltage and current are all enhanced with the BT nanoparticles,which reached 200 V and 0.24μA in TENG with 40 wt% BT nanoparticles,respectively.The selected device exhibited the power of 0.16 mW and employed to demonstrate its ability to power wearable/portable electronics by lighting the LEDs.
基金supported by the National Nature Science Foundation of China(Grant Nos.51772239,51761145024)the Fundamental Research Funds for the Central Universities(XJTU),the Key Scientific and Tech-nological Innovation Team of Shannxi Province(Grant No.2018TD-024)the“111”Project(Grant No.B14040).
文摘In this work,we report the dielectric and ferroelectric properties of CuO-doped(1-x)[0.5573Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.4427PbTiO_(3)]-xBa(Zn_(1/3)Nb_(2/3))_(3)(PMNT-xBZN)relaxor ferrielectric ceramic samples with x=0.1725,0.1925,02125 and 0.2325,which were fabricated by a conventional solid-state reaction method.By introducing the CuO into PMNT-xBZN,the sintering temperature of this system is drastically lowered from 1280℃to 1120℃.The second pyrochlore phase,which is often generated during sintering at high temperature,is also inhibited.Meanwhile,broad dielectric peaks with strong dielectric relaxation characteristics are observed from150℃to 100℃.Slim and slanted P-E hysteresis loops and purely electrostrictive strains with V-shape are obtained simultaneously in studied compositions from 30℃to 150℃.These results suggest that CuO could effectively lower the sintering temperature while maintaining the dielectric and ferroelectric properties of PMNT-xBZN relaxor ferroelectric ceramics.
基金This work was supported by the China-Poland International Collaboration Fund of National Natural Science Foundation of China(No.51961135301)National Natural Science Foundation of China(No.51702259)+2 种基金the National Key R&D Foundation of the Ministry of Science and Technology(No.2018YFB1107405)the Basic Research Program of Shenzhen(No.JCYJ20170306155944271)the Fundamental Research Funds for the Central Universities(No.06450-G2019KY0601,3102019MS0406).
文摘The luminescence modulation behaviour under the in-situ electric field of rare-earth doped KSr_(2)Nb_(5)O_(15) ceramics opened a new door for the development of dielectric materials.Where the understanding the effect of rare-earth doping on the electric properties of host,especially at the similar doping concentration with luminescence researches(low concentrations)is very important for the exploration of mechanism of electric-luminescent coupling effect.In this work,Nd^(3+)-doped KSr_(2)Nb_(5)O_(15)(KSN-xNd)ceramics were synthesized,and the electric properties were investigated systematically.Our results suggest that the Nd^(3+) doping slightly increased the phase transition temperatures and improved the piezoelectric response of KSr_(2)Nb_(5)O_(15).Most importantly,a bidirectional dielectric tunability is revealed in KSr_(2)Nb_(5)O_(15).The dielectric permittivity can be adjusted by the DC electric bias,with tunability ranging from12.3% to 21.9%.The related mechanism and relationship between the bidirectional dielectric tunability and ferroelectricity are revealed by temperature-dependent dielectric and ferroelectric characterization.The researches of electric properties and bidirectional dielectric tunability of KSN-based ceramics paved the way to further exploration of electric-luminescent coupling mechanism.
文摘Cassidy et al.of Trinity College in Dublin,Ireland,studied the social structure of farming communities,focusing on the ancient nobles buried in passage tombs(a channel-style megalithic tomb structure in Europe).Newgrange,built by complex engineering technology,is the most famous stone tunnel tomb in Ireland and one of the most famous prehistoric cemeteries in the country.The tomb is at the end of a stone-lined passage,with an opening like a window above the mausoleum entrance.On the shortest day of the year(winter solstice),this opening allows sunlight to enter the tomb.Researchers conducted DNA analysis of ancient human remains found in the tomb,revealing a rare and unexpected incident of incest.A man buried in Newgrange's tomb about 5000 years ago was the offspring of an incestuous marriage:his parents were either siblings or parents and children.This discovery led the researchers to speculate that the nobles associated with this magnificent tomb may have maintained their bloodlines through incest.
基金This work was supported by the National Key R&D Program of China(No.2021YFB3602000)the Fundamental Research Funds for the Central Universities(No.WK5290000003).
文摘There are significant differences in the extent of impurity incorporation on different crystallographic directions of GaN microstructures,and the impurity-related deep energy level behavior will have a significant impact on device performance.However,a comprehensive understanding of the effect of lateral growth on device performance has not been achieved due to the lack of comprehensive spatial distribution characterization of the optical behavior and impurity incorporation in GaN microstructures.We present a comprehensive study of the optical behavior and growth mechanism of self-assembled GaN microdisks using nanoscale spatially resolved cathodoluminescence(CL)mapping.We have found a clear growth orientation-dependent optical behavior of the lateral and vertical growth sectors of self-assembled GaN microcrystals.The lateral growth sector,i.e.,the{101¯1}-growth sector,forms six side facets of the microdisk and shows significant near-bandgap emission(NBE)and weak deep energy level luminescence.Cavity effect enhanced emission was found for the first time in such a truncated hexagonal Na-flux GaN microdisk system with an ultra-smooth surface(Ra<0.7 nm)and low stress.The self-assembled microdisk shows significant ultraviolet(UV)lasing action(main lasing peak wavelength 370.9 nm,quality factor 1278,threshold 6×10^(4)μJ/cm^(2))under pulsed optical pumping.We believe that the appearance of UV lasing action may be related to the light limitation on the six side facets of the lateral growth of the GaN microdisk,the high structural quality,the low content of deep energy level defects,the low surface roughness,and the low stress.
基金Jiangxi Provincial Department of Science and Technology(20212BDH80017)National Natural Science Foundation of China(62001369)。
文摘In this study,we theoretically proposed a method to achieve an electromagnetically induced transparency(EIT)-like effect in a whispering gallery mode resonator(WGMR)and experimentally validated the method in a lithium niobate(LN)device.Benefitting from the electro-optic and inverse piezoelectric effects of the LN material,two modes of the LN WGMR that are close in frequency can be tuned at different tuning rates,resulting in EIT-like resonance lineshapes.By varying the electric field applied to the LN WGMR,the full dynamic of the EIT-like phenomenon can be precisely controlled.The experimental results agreed well with the calculations based on the coupled mode theory.Moreover,we observed a hysteresis resulting from the photorefractive effect of LN.We believe our proposed method and demonstrated devices offer a way to control an EIT-like effect,which could have potential applications in light storage,quantum information processing,and enhanced sensing techniques.
基金supported by the National Natural Science Foundation of China(Grant Nos.62172325 and 32070663)the China Postdoctoral Science Foundation(Grant No.2020M673420)+2 种基金the Fundamental Research Funds for the Central Universities,Chinathe World-Class Universities(Disciplines)the Characteristic Development Guidance Funds for the Central Universities,China。
文摘Arabidopsis thaliana is an important and long-established model species for plant molecular biology,genetics,epigenetics,and genomics.However,the latest version of reference genome still contains a significant number of missing segments.Here,we reported a high-quality and almost complete Col-0 genome assembly with two gaps(named Col-XJTU)by combining the Oxford Nanopore Technologies ultra-long reads,Pacific Biosciences high-fidelity long reads,and Hi-C data.The total genome assembly size is 133,725,193 bp,introducing 14.6 Mb of novel sequences compared to the TAIR10.1 reference genome.All five chromosomes of the Col-XJTU assembly are highly accurate with consensus quality(QV)scores>60(ranging from 62 to 68),which are higher than those of the TAIR10.1 reference(ranging from 45 to 52).We completely resolved chromosome(Chr)3 and Chr5 in a telomere-to-telomere manner.Chr4 was completely resolved except the nucleolar organizing regions,which comprise long repetitive DNA fragments.The Chrl centromere(CEN1),reportedly around 9 Mb in length,is particularly challenging to assemble due to the presence of tens of thousands of CEN180 satellite repeats.Using the cutting-edge sequencing data and novel computational approaches,we assembled a 3.8-Mb-long CEN1 and a 3.5-Mb-long CEN2.We also investigated the structure and epigenetics of centromeres.Four clusters of CEN180 monomers were detected,and the centromere-specific histone H3-like protein(CENH3)exhibited a strong preference for CEN180 Cluster 3.Moreover,we observed hypomethylation patterns in CENH3-enriched regions.We believe that this high-quality genome assembly,Col-XJTU,would serve as a valuable reference to better understand the global pattern of centromeric polymorphisms,as well as the genetic and epigenetic features in plants.
基金supported by the National Natural Science Foundation of China(Grant Nos.61822309,61773310&U1736205)
文摘As a typical representative of the so-called cyber-physical system,smart grid reveals its high efficiency,robustness and reliability compared with conventional power grid.However,due to the deep integration of electrical components and computinginformation in cyber space,smart grid is vulnerable to malicious attacks,especially for a type of attacks named false data injection attacks(FDIAs).FDIAs are capable of tampering meter measurements and affecting the results of state estimation stealthily,which severely threat the security of smart grid.Due to the significantinfluence of FDIAs on smart grid,the research related to FDIAs has received considerable attention over the past decade.This paper aims to summarize recent advances in FDIAs against smart grid state estimation,especially from the aspects of background materials,construction methods,detection and defense strategies.Moreover,future research directions are discussed and outlined by analyzing existing results.It is expected that through the review of FDIAs,the vulnerabilities of smart grid to malicious attacks can be further revealed and more attention can be devoted to the detection and defense of cyber-physical attacks against smart grid.
基金the National Natural Science Foundation of China(Grant nos.51672226,51772239)the Fundamental Research Funds for the Central Universities(XJTU).
文摘In the present work,the nature of phase evolution of(1x)(Na_(0.5)Bi_(0.5))TiO_(3)-xSrTiO_(3)(NBT-xST)solid solutions with x of 0e0.6 is revealed by characterizing the dielectric and ferroelectric properties.Two unique dielectric anomalies associated with high-temperature nanoregions(PNRs)in the ergodic relaxor(ER)state and low-temperature PNRs in the nonergodic relaxor(NR)state are identified.Characteristic temperatures,including TB,TRT*,Tm,Td and TT*,are determined in fresh and poled states on the basis of the characteristics of the evolution of these two dielectric anomalies.The whole evolution of the transition from the NR state to the ER state is reflected by the temperature-dependent polarization versus electric field(P-E)hysteresis loops,i.e.,from the square loops,via the double-like loops,to the slim loops.The characteristic temperatures,including TP-N,TN-R and TR-dis,are determined by the characteristics of the evolution of P-E loops.Accordingly,a phase diagram of NBT-xST was constructed according to these characteristic temperatures.Most importantly,the relationship between polarization responses and heterogeneous polar phase coexistence has been established and a schematic diagram is given.This work will help to understand the phase evolution and its impact on the macroscopic properties of NBT and the associated NBT-based solid solutions.
