期刊文献+
任意字段
题名或关键词
题名
关键词
摘要
作者
第一作者
机构
刊名
分类号
参考文献
作者简介
基金资助
栏目信息
共找到6,576篇文章
< 1 2 … 250 >
每页显示 20 50 100
已选0条
引用分析
参考文献
引证文献
 统计分析
检索结果
已选文献
显示方式：
A Fine-Grained RecognitionModel based on Discriminative Region Localization and Efficient Second-Order Feature Encoding 认领 引用
1
作者 Xiaorui Zhang Yingying Wang +3 位作者 Wei Sun Shiyu Zhou Haoming Zhang Pengpai Wang 《Computers, Materials & Continua》 SCIE EI 2026年第4期946-965,共20页
Discriminative region localization and efficient feature encoding are crucial for fine-grained object recognition.However,existing data augmentation methods struggle to accurately locate discriminative regions in comp... Discriminative region localization and efficient feature encoding are crucial for fine-grained object recognition.However,existing data augmentation methods struggle to accurately locate discriminative regions in complex backgrounds,small target objects,and limited training data,leading to poor recognition.Fine-grained images exhibit“small inter-class differences,”and while second-order feature encoding enhances discrimination,it often requires dual Convolutional Neural Networks(CNN),increasing training time and complexity.This study proposes a model integrating discriminative region localization and efficient second-order feature encoding.By ranking feature map channels via a fully connected layer,it selects high-importance channels to generate an enhanced map,accurately locating discriminative regions.Cropping and erasing augmentations further refine recognition.To improve efficiency,a novel second-order feature encoding module generates an attention map from the fourth convolutional group of Residual Network 50 layers(ResNet-50)and multiplies it with features from the fifth group,producing second-order features while reducing dimensionality and training time.Experiments on Caltech-University of California,San Diego Birds-200-2011(CUB-200-2011),Stanford Car,and Fine-Grained Visual Classification of Aircraft(FGVC Aircraft)datasets show state-of-the-art accuracy of 88.9%,94.7%,and 93.3%,respectively. 展开更多
关键词 Fine-grained recognition feature encoding data augmentation second-order feature discriminative regions
暂未订购 下载PDF
Firing dynamics in a second-order memcapacitor-based FitzHugh–Nagumo neuron with multiscale memory 认领 引用
2
作者 Zhijun Li Pengyang Li 《Chinese Physics B》 SCIE EI CAS CSCD 2026年第6期247-259,共13页
This paper presents a second-order memcapacitor(CM)-based FitzHugh–Nagumo(FHN)neuron model designed to emulate multiscale memory mechanisms observed in biological neurons.The memcapacitor incorporates two internal st... This paper presents a second-order memcapacitor(CM)-based FitzHugh–Nagumo(FHN)neuron model designed to emulate multiscale memory mechanisms observed in biological neurons.The memcapacitor incorporates two internal state variables—a fast variable that enables rapid response and a slow variable that enables gradual adaptation—replacing the linear membrane capacitor in the classical FHN circuit to form a four-dimensional neuronal system.The electrical activities of the neuron are systematically investigated using bifurcation diagrams,Lyapunov exponents,and a twoparameter dynamical map.Numerical simulations reveal that variations in excitation frequency and amplitude can induce transitions among chaotic firing,multiperiodic firing,and single-periodic spiking.Furthermore,the model demonstrates pronounced multistability governed by the memcapacitor's initial states,where distinct periodic and chaotic attractors coexist within separate basins of attraction—a direct manifestation of the multiscale memory interaction.By tailoring external stimuli and internal parameters,the neuron successfully reproduces eight quintessential neuromorphic behaviors,including phasic and tonic spiking,mixed-mode oscillations,subthreshold oscillations,inhibition-induced spiking,rebound spikes,bistability,and Class 2 excitability.Finally,an analog FHN circuit integrated with a secondorder memcapacitor emulator is implemented using off-the-shelf electronic components.Circuit simulations demonstrate excellent agreement with numerical analyses,thereby validating both the model's correctness and its physical realizability for neuromorphic engineering applications. 展开更多
关键词 second-order memcapacitor FitzHugh–Nagumo neuron firing dynamics neuromorphic computing
暂未订购 下载PDF
Entry trajectory optimization for cross-domain morphing vehicles by hybrid sequential second-order cone programming 认领 引用
3
作者 Zheng Li Zhenyue Jia +2 位作者 Zheng Fang Hongmiao Zhou Jianqiao Yu 《Defence Technology（防务技术）》 SCIE EI CAS CSCD 2026年第4期149-175,共27页
This paper proposes a hybrid sequential second-order cone programming(HSSOCP)method with a three-layer scheme for the entry trajectory optimization of the cross-domain morphing vehicles(CDMVs).By defining the new morp... This paper proposes a hybrid sequential second-order cone programming(HSSOCP)method with a three-layer scheme for the entry trajectory optimization of the cross-domain morphing vehicles(CDMVs).By defining the new morphing rate control variable and using relaxation techniques to relax the bank angle constraint,the SOCP-based entry problem is constructed.A dynamic relaxation penal-ization technique is developed in the first layer to overcome artificial infeasibility and significantly enhance initialization robustness.A novel standard oscillation identification(SOI)method is proposed to precisely identify the iteration oscillations of basic SSOCP in the second layer,which can significantly improve the solution accuracy.A soft-trust-region strategy is applied in the third layer to eliminate oscillations and accelerate convergence.Simulation results of two scenarios demonstrate that the proposed SOI method effectively avoids non-standard oscillation interference versus traditional methods.The morphing aircraft can complete tasks better with a 7.01%and 10.43%reduction in heat load respectively compared to fixed-wing aircraft.The HSSOCP method can maintain accuracy while reducing computation time by 63.47%and 73.86%versus VATSSOCP.Monte Carlo simulations further validate the robustness. 展开更多
关键词 Cross-domain vehicle Morphing vehicle Entry trajectory optimization Sequential second-order cone programming Iteration oscillation Hybrid scheme
暂未订购 下载PDF
Second-order correlated interference with multi-wavelength thermal-light beams 认领 引用
4
作者 De-Sheng Wang Yi-Ning Zhao +5 位作者 Lingxin Kong Su-Heng Zhang Chong Wang Cheng Ren Yuehua Su De-Zhong Cao 《Chinese Physics B》 SCIE EI CAS CSCD 2026年第2期374-382,共9页
A method for correlating thermal light over a wide spectral range is proposed.A multi-wavelength pseudothermal source,prepared by projecting laser beams of multiple wavelengths(650 nm,635 nm,532 nm,and 473 nm)onto a m... A method for correlating thermal light over a wide spectral range is proposed.A multi-wavelength pseudothermal source,prepared by projecting laser beams of multiple wavelengths(650 nm,635 nm,532 nm,and 473 nm)onto a moving thin ground glass plate,is employed in a double-slit interference experiment.The ground glass plate induces random phase differences between light beams of different wavelengths passing through it.This initial random phase difference significantly influences the high-order intensity correlation functions of multi-wavelength thermal beams.Experimentally,second-order correlated interference patterns,including subwavelength interference,of pseudothermal beams with different wavelengths are observed in the intensity correlation measurements.This method facilitates applications of correlated thermal photons in quantum information processing and quantum imaging. 展开更多
关键词 correlated interference multi-wavelength thermal light second-order correlation function
暂未订购 下载PDF
Photo-crosslinked Second-order Nonlinear Optical Polymer Films with Large Nonlinear Optical Effect and High Thermostability 认领 引用
5
作者 Pan-Pan Qiao Qian-Qian Li Zhen Li 《Chinese Journal of Polymer Science》 SCIE EI CAS CSCD 2026年第4期1007-1016,I0012,共10页
One of the most significant challenges in commercializing organic second-order nonlinear optical(NLO)materials lies in the inherent trade-off between nonlinearity and stability.A key factor in mitigating this compromi... One of the most significant challenges in commercializing organic second-order nonlinear optical(NLO)materials lies in the inherent trade-off between nonlinearity and stability.A key factor in mitigating this compromise is achieving precise temporal synchronization between the formation of the cross-linked network and the establishment of an optimal non-centrosymmetric alignment of the chromophores.Guided by this principle,we developed a series of NLO polymers incorporating multiple ether chains with low rotational energy barriers,which facilitate molecular reorientation during electric field poling,thereby enhancing the NLO response effectively.Combined with an optimized photocrosslinking strategy,the resulting PX4o/PETMP doped film achieved large macroscopic NLO coefficient of 190 pm·V-1and thermal degradation temperature as high as 120℃.This work offers a universal approach to alleviating the“nonlinearity-stability”trade-off in a wide range of polymeric systems. 展开更多
关键词 Second-order nonlinear optical effect Thermostability "Nonlinearity-stability"trade-off Photo-crosslinking
暂未订购 下载PDF
Nonlinear Vibration and Resonance Behavior of Semi-Rigid Steel Frames with Second-Order Effects 认领 引用
6
作者 Dung Bao Trung Le Quoc AnhVu Hai Quang Nguyen 《Structural Durability & Health Monitoring》 EI 2026年第4期135-152,共18页
The vibration and resonance behavior of steel frame structures are significantly affected by connection flexibility and geometric nonlinearity.Conventional vibration analyses often assume fully rigid beam-column conne... The vibration and resonance behavior of steel frame structures are significantly affected by connection flexibility and geometric nonlinearity.Conventional vibration analyses often assume fully rigid beam-column connections and neglect second-order effects,which can lead to inaccurate predictions of natural frequencies and resonance conditions.This study proposes a finite element-based approach for the vibration analysis of planar steel frames with linear and nonlinear semi-rigid connections,explicitly incorporating geometric nonlinearity.Beam-column connections aremodeled using nonlinearmoment-rotation relationships,while elastic and geometric stiffnessmatrices,together with a consistentmassmatrix,are integrated into the governing dynamic equations.Thetime-history response is computed using the Newmark integration scheme.The proposed formulation is validated through benchmark examples and comparisons with published results and commercial finite element software.Numerical results reveal that the combined effects of semi-rigid connections and geometric nonlinearity significantly alter the effective structural stiffness,leading to noticeable variations in natural vibration frequencies.In particular,the fundamental frequency evolves during dynamic response,resulting in resonance shifting and time-dependent resonance behavior.These findings suggest that resonance in steel frames with semi-rigid connections should be regarded as a state-dependent phenomenon rather than a fixed structural property,with important implications for vibration assessment and resonance control in structural design. 展开更多
关键词 Semi-rigid connections steel frames second-order vibration resonance behavior finite element analysis
暂未订购 下载PDF
Second-order topological insulator in twisted bilayer graphene with small twist angles 认领 引用
7
作者 Fenghua Qi Jie Cao +1 位作者 Xingfei Zhou Guojun Jin 《Chinese Physics B》 SCIE EI CAS CSCD 2025年第11期484-490,共7页
In recent years,the study of higher-order topological states and their material realizations has become a research frontier in topological condensed matter physics.We demonstrate that twisted bilayer graphene with sma... In recent years,the study of higher-order topological states and their material realizations has become a research frontier in topological condensed matter physics.We demonstrate that twisted bilayer graphene with small twist angles behaves as a second-order topological insulator possessing topological corner charges.Using a tight-binding model,we compute the topological band indices and corner states of finite-sized twisted bilayer graphene flakes.It is found that for any small twist angle,whether commensurate or incommensurate,the gaps both below and above the flat bands are associated with nontrivial topological indices.Our results not only extend the concept of second-order band topology to arbitrary small twist angles but also confirm the existence of corner states at acute-angle corners. 展开更多
关键词 second-order topological insulators twisted bilayer graphene
暂未订购 下载PDF
Theoretical study on the influence of a polarizable environment on the second-order nonlinear optical properties of substituted naphthalene isomers 认领 引用
8
作者 YE Jinting WANG Lihui +1 位作者 QIU Yongqing ZHANG Qiang 《分子科学学报》 CAS 2025年第6期19-27,共9页
The design of molecular configurations for high-efficiency nonlinear optical(NLO)materials has attracted considerable interest in recent years.In this work,quantum chemical methods are employed to investigate the seco... The design of molecular configurations for high-efficiency nonlinear optical(NLO)materials has attracted considerable interest in recent years.In this work,quantum chemical methods are employed to investigate the second-order NLO properties of a series of mono-and disubstituted naphthalene derivatives in both the gas phase and a solid polarizable environment.The results demonstrate that the substitution position strongly influences the charge-transfer architecture and,consequently,the total first hyperpolarizability(βtot)of the studied systems.In the gas phase,the calculatedβtot values for the 1,5-and 2,6-naphthylene-substituted derivatives(N1,5-TPA-TRZ and N2,6-TPA-TRZ),which exhibit through-bond charge transfer(TBCT)character,are markedly higher than that of the 1,8-naphthylene-substituted analogue(N1,8-TPA-TRZ)with throughspace charge transfer(TSCT)character.The extendedπ-conjugation in the TBCT systems leads to a pronounced red-shift in the absorption spectra and lower electronic transition energies,contributing to their enhanced second-order NLO responses.Furthermore,solid-state polarization effects were examined using a combined approach of range-separated hybrid(RSH)functionals and a polarizable continuum model(PCM).This analysis reveals a substantial increase in βtot for N2,6-TPA-TRZ,from 5.73×10-49 C3·m3·J-2 in the gas phase to 1.59×10-48 C3·m3·J-2 under solid-like conditions.These findings highlight that introducing donor and acceptor groups at the 2,6-positions of naphthalene derivatives offers a promising strategy for developing high-performance NLO materials. 展开更多
关键词 through-bond charge transfer through-space charge transfer second-order nonlinear optical response tuned rangeseparated hybrid functional
暂未订购 下载PDF
Sufficient and Necessary Conditions for Leader-Following Consensus of Second-Order Multi-Agent Systems via Intermittent Sampled Control 认领 引用
9
作者 Ziyang Wang Yuanzhen Feng +1 位作者 Zhengxin Wang Cong Zheng 《Computers, Materials & Continua》 SCIE EI 2025年第6期4835-4853,共19页
Continuous control protocols are extensively utilized in traditional MASs,in which information needs to be transmitted among agents consecutively,therefore resulting in excessive consumption of limited resources.To de... Continuous control protocols are extensively utilized in traditional MASs,in which information needs to be transmitted among agents consecutively,therefore resulting in excessive consumption of limited resources.To decrease the control cost,based on ISC,several LFC problems are investigated for second-order MASs without and with time delay,respectively.Firstly,an intermittent sampled controller is designed,and a sufficient and necessary condition is derived,under which state errors between the leader and all the followers approach zero asymptotically.Considering that time delay is inevitable,a new protocol is proposed to deal with the time-delay situation.The error system’s stability is analyzed using the Schur stability theorem,and sufficient and necessary conditions for LFC are obtained,which are closely associated with the coupling gain,the system parameters,and the network structure.Furthermore,for the case where the current position and velocity information are not available,a distributed protocol is designed that depends only on the sampled position information.The sufficient and necessary conditions for LFC are also given.The results show that second-order MASs can achieve the LFC if and only if the system parameters satisfy the inequalities proposed in the paper.Finally,the correctness of the obtained results is verified by numerical simulations. 展开更多
关键词 Intermittent sampled control leader-following consensus time delay second-order multi-agent system
暂未订购 下载PDF
Electromagnetically induced transparency and second-order sideband effects in a Laguerre–Gaussian cavity optorotational system with Kerr medium 认领 引用
10
作者 Jing-Xuan Li Su-Mei Huang Ai-Xi Chen 《Communications in Theoretical Physics》 SCIE CAS CSCD 2025年第7期54-62,共9页
In this paper,we investigate the phenomena of electromagnetically induced transparency and the generation of second-order sideband in a Laguerre–Gaussian cavity optorotational system with a Kerr nonlinear medium.Usin... In this paper,we investigate the phenomena of electromagnetically induced transparency and the generation of second-order sideband in a Laguerre–Gaussian cavity optorotational system with a Kerr nonlinear medium.Using the perturbation method,we analyze the first-and second-order sideband generations in the output field from the system under the actions of a strong control field and a weak probe field.Numerical simulations show that the Kerr nonlinearity can lead to the occurrence of the asymmetric line shape in the transmission of the probe field.Comparing with traditional scheme for generating the second-order sideband,our spectral shape of the second-order sideband is amplified and becomes asymmetric,which has potential applications in precision measurement,high-sensitivity devices,and frequency conversion. 展开更多
关键词 Laguerre–Gaussian cavity optorotational system electromagnetically induced transparency second-order sideband generation Kerr medium
暂未订购 下载PDF
Stabilization of second-order bilinear systems with time delay by a class of bounded feedbacks 认领 引用
11
作者 Khalil El Kazoui Hassan Ezzaki 《Control Theory and Technology》 EI CSCD 2025年第4期579-589,共11页
The stabilization problem of second-order bilinear systems with time delay is investigated.Feedback controls are chosen so that the strong and exponential stabilization of the system is ensured.The obtained results ar... The stabilization problem of second-order bilinear systems with time delay is investigated.Feedback controls are chosen so that the strong and exponential stabilization of the system is ensured.The obtained results are illustrated by wave and beam equations with simulation. 展开更多
关键词 Second-order systems Bilinear systems Time delay Strong stabilization Exponential stabilization Wave equation Beam equation
Second-Order Transconductance-Mode Universal Filter Based on CCCⅡand OTA 认领 引用
12
作者 HOU Jingqiang YE Xiangdong +1 位作者 ZHENG Jie LI Yongan 《Wuhan University Journal of Natural Sciences》 CAS CSCD 2025年第5期441-446,共6页
This research,based on Mason's formula,proposes a novel design for a second-order transconductance-mode universal filter with the operational transconductance amplifier(OTA)as the core and the second-generation cu... This research,based on Mason's formula,proposes a novel design for a second-order transconductance-mode universal filter with the operational transconductance amplifier(OTA)as the core and the second-generation current-controlled conveyor(CCCⅡ)as the auxiliary.The circuit incorporates two OTAs,one CCCⅡ,two grounded capacitors,and one grounded resistor.The quality factor Q and natural frequency fo of the filter can be electronically tuned and are not sensitive to temperature.The input and output terminals of the cir-cuit exhibit no loading effect,and the sensitivity of the circuit is low.At last,alternating frequency analysis,parameter scanning analysis,and temperature scanning analysis have been carried out by using Multisim software,confirming the correctness and effectiveness of the designed circuit. 展开更多
关键词 second-order universal filter transconductance-mode circuit second-generation current-controlled conveyor(CCCII) operational transconductance amplifier(OTA)
暂未订购 下载PDF
Second-Order Adjoint Sensitivity Analysis Methodology for Computing Exactly Response Sensitivities to Uncertain Parameters and Boundaries of Linear Systems: Mathematical Framework 认领 引用 被引量：3
13
作者 Dan Gabriel Cacuci 《American Journal of Computational Mathematics》 2020年第3期329-354,共26页
This work presents the “Second-Order Comprehensive Adjoint Sensitivity Analysis Methodology (2nd-CASAM)” for the efficient and exact computation of 1st- and 2nd-order response sensitivities to uncertain parameters a... This work presents the “Second-Order Comprehensive Adjoint Sensitivity Analysis Methodology (2nd-CASAM)” for the efficient and exact computation of 1st- and 2nd-order response sensitivities to uncertain parameters and domain boundaries of linear systems. The model’s response (i.e., model result of interest) is a generic nonlinear function of the model’s forward and adjoint state functions, and also depends on the imprecisely known boundaries and model parameters. In the practically important particular case when the response is a scalar-valued functional of the forward and adjoint state functions characterizing a model comprising N parameters, the 2nd-CASAM requires a single large-scale computation using the First-Level Adjoint Sensitivity System (1st-LASS) for obtaining all of the first-order response sensitivities, and at most N large-scale computations using the Second-Level Adjoint Sensitivity System (2nd-LASS) for obtaining exactly all of the second-order response sensitivities. In contradistinction, forward other methods would require (N2/2 + 3 N/2) large-scale computations for obtaining all of the first- and second-order sensitivities. This work also shows that constructing and solving the 2nd-LASS requires very little additional effort beyond the construction of the 1st-LASS needed for computing the first-order sensitivities. Solving the equations underlying the 1st-LASS and 2nd-LASS requires the same computational solvers as needed for solving (i.e., “inverting”) either the forward or the adjoint linear operators underlying the initial model. Therefore, the same computer software and “solvers” used for solving the original system of equations can also be used for solving the 1st-LASS and the 2nd-LASS. Since neither the 1st-LASS nor the 2nd-LASS involves any differentials of the operators underlying the original system, the 1st-LASS is designated as a “first-level” (as opposed to a “first-order”) adjoint sensitivity system, while the 2nd-LASS is designated as a “second-level” (rather than a “second-order”) adjoint sensitivity system. Mixed second-order response sensitivities involving boundary parameters may arise from all source terms of the 2nd-LASS that involve the imprecisely known boundary parameters. Notably, the 2nd-LASS encompasses an automatic, inherent, and independent “solution verification” mechanism of the correctness and accuracy of the 2nd-level adjoint functions needed for the efficient and exact computation of the second-order sensitivities. 展开更多
关键词 Second-Order Comprehensive Adjoint Sensitivity Analysis Methodology (2nd-CASAM) First-Level Adjoint Sensitivity System (1st-LASS) Second-Level Adjoint Sensitivity System (2nd-LASS) Operator-Type Response Second-Order Sensitivities to Uncertain Model Boundaries Second-Order Sensitivities to Uncertain Model Parameters
暂未订购 下载PDF
Horizontal dynamic response of a large-diameter pipe pile considering the second-order effect of axial force 认领 引用 被引量：3
14
作者 Luan Lubao Ding Xuanming +2 位作者 Zhou Wei Zheng Changjie Qu Liming 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2018年第3期567-579,共13页
The second-order effect of axial force on horizontal vibrating characteristics of a large-diameter pipe pile is theoretically investigated.Governing equations of the pile-soil system are established based on elastodyn... The second-order effect of axial force on horizontal vibrating characteristics of a large-diameter pipe pile is theoretically investigated.Governing equations of the pile-soil system are established based on elastodynamics.Threedimensional wave equations of soil are decoupled through differential transformation and variable separation.Consequently,expressions of soil displacements and horizontal resistances can be obtained.An analytical solution of the pile is derived based on continuity conditions between the pile and soil,subsequently from which expressions of the complex impedances are deduced.Analyses are carried out to examine the second-order effect of axial force on the horizontal vibrating behavior of the pipe pile.Some conclusions can be summarized as follows： stiffness and damping factors are decreased with the application of axial force on the pile head; distributions of the pile horizontal displacement and rotation angle are regenerated due to the second-order effect of the applied axial force; and redistributions of the bending moment and shearing force occur due to the second-order effect of the applied axial force. 展开更多
关键词 axial force second-order effect horizontal vibration pipe pile analytical solution
暂未订购 下载PDF
Cluster consensus of second-order multi-agent systems via pinning control 认领 引用 被引量：11
15
作者 路晓庆 Francis Austin 陈士华 《Chinese Physics B》 SCIE EI CAS 2010年第12期90-96,共7页
This paper investigates the cluster consensus problem for second-order multi-agent systems by applying the pinning control method to a small collection of the agents. Consensus is attained independently for different ... This paper investigates the cluster consensus problem for second-order multi-agent systems by applying the pinning control method to a small collection of the agents. Consensus is attained independently for different agent clusters according to the community structure generated by the group partition of the underlying graph and sufficient conditions for both cluster and general consensus are obtained by using results from algebraic graph theory and the LaSalle Invariance Principle. Finally, some simple simulations are presented to illustrate the technique. 展开更多
关键词 second-order multi-agent systems cluster consensus pinning control LaSalle invariance principle
暂未订购 下载PDF
NUMERICAL SIMULATION OF METHANE-AIR TURBULENT JET FLAME USING A NEW SECOND-ORDER MOMENT MODEL 认领 引用 被引量：6
16
作者 陈兴隆 周力行 张健 《Acta Mechanica Sinica》 SCIE EI CAS 2000年第1期41-47,共7页
A new second-order moment model for turbulent combustion is applied in the simulation of methane-air turbulent jet flame. The predicted results are compared with the experimental results and with those predicted using... A new second-order moment model for turbulent combustion is applied in the simulation of methane-air turbulent jet flame. The predicted results are compared with the experimental results and with those predicted using the well-known EBU-Arrhenius model and the original second-order moment model. The comparison shows the advantage of the new model that it requires almost the same computational storage and time as that of the original second-order moment model, but its modeling results are in better agreement with experiments than those using other models. Hence, the new second-order moment model is promising in modeling turbulent combustion with NOx formation with finite reaction rate for engineering application. 展开更多
关键词 turbulent combustion second-order moment model numerical simulation
暂未订购 下载PDF
Study of(e,2e) process on potassium at 6 e V-60 eV above threshold in a second-order Born approximation 认领 引用 被引量：5
17
作者 王旸 周雅君 焦利光 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第8期197-201,共5页
The standard distorted wave Born approximation （DWBA） method has been extended to second-order Born amplitude in order to describe the multiple interactions between the projectile and the atomic target. Second-order... The standard distorted wave Born approximation （DWBA） method has been extended to second-order Born amplitude in order to describe the multiple interactions between the projectile and the atomic target. Second-order DWBA calculations have been preformed to investigate the triple differential cross sections （TDCS） of coplanar doubly symmetric （e, 2e） collisions for the alkali target potassium at excess energies of 6 eV-60 eV. Compared with the previous first-order DWBA calculations, the present theoretical model improves the degree of agreement with experiments, especially for the backward scattering angle region of TDCS. This indicates that the present second-order Born term is capable of giving a reasonable correction to the DWBA model in studying coplanar symmetric （e, 2e） problems in low and intermediate energy ranges. 展开更多
关键词 second-order Born approximation （e 2e） collisions potassium triple differential cross section
暂未订购 下载PDF
Formation tracking control for time-delayed multi-agent systems with second-order dynamics 认领 引用 被引量：11
18
作者 Han Liang Dong Xiwang +1 位作者 Li Qingdong Ren Zhang 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2017年第1期348-357,共10页
In this paper, formation tracking control problems for second-order multi-agent systems（MASs） with time-varying delays are studied, specifically those where the position and velocity of followers are designed to for... In this paper, formation tracking control problems for second-order multi-agent systems（MASs） with time-varying delays are studied, specifically those where the position and velocity of followers are designed to form a time-varying formation while tracking those of the leader. A neighboring relative state information based formation tracking protocol with an unknown gain matrix and time-varying delays is presented. The formation tracking problems are then transformed into asymptotically stable problems. Based on the Lyapunov-Krasovskii functional approach, conditions sufficient for second-order MASs with time-varying delays to realize formation tracking are examined. An approach to obtain the unknown gain matrix is given and, since neighboring relative velocity information is difficult to measure in practical applications, a formation tracking protocol with time-varying delays using only neighboring relative position information is introduced. The proposed results can be used on target enclosing problems for MASs with second-order dynamics and time-varying delays. An application for target enclosing by multiple unmanned aerial vehicles（UAVs） is given to demonstrate the feasibility of theoretical results. 展开更多
关键词 Formation tracking control Multiple unmanned aerialvehicles Second-order dynamics Time-delayed multi-agentsystems Time-varying formation
暂未订购 下载PDF
Evaluation of second-order Zeeman frequency shift in NTSC-F2 认领 引用 被引量：3
19
作者 Jun-Ru Shi Xin-Liang Wang +5 位作者 Yang Bai Fan Yang Yong Guan Dan-Dan Liu Jun Ruan Shou-Gang Zhang 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第7期163-170,共8页
Caesium atomic fountain clock is a primary frequency standard,which realizes the duration of second.Its performance is mostly dominated by the frequency accuracy,and the C-field induced second-order Zeeman frequency s... Caesium atomic fountain clock is a primary frequency standard,which realizes the duration of second.Its performance is mostly dominated by the frequency accuracy,and the C-field induced second-order Zeeman frequency shift is the major effect,which limits the accuracy improvement.By applying a high-precision current supply and high-performance magnetic shieldings,the C-field stability has been improved significantly.In order to achieve a uniform C-field,this paper proposes a doubly wound C-field solenoid,which compensates the radial magnetic field along the atomic flight region generated by the lead-out single wire and improves the accuracy evaluation of second-order Zeeman frequency shift.Based on the stable and uniform C-field,we launch the selected atoms to different heights and record the magnetically sensitive Ramsey transition|F=3,mF=-1→|F=4,mF=-1 central frequency,obtaining this frequency shift as 131.03×10-15and constructing the C-field profile(σ=0.15 n T).Meanwhile,during normal operation,we lock NTSC-F2 to the central frequency of the magnetically sensitive Ramsey transition|F=3,mF=-1→|F=4,mF=-1 fringe for ten consecutive days and record this frequency fluctuation in time domain.The first evaluation of second-order Zeeman frequency shift uncertainty is 0.10×10-15.The total deviation of the frequency fluctuation on the clock transition induced by the C-field instability is less than 2.6×10-17.Compared with NTSC-F1,NTSC-F2,there appears a significant improvement. 展开更多
关键词 caesium atomic fountain clock second-order Zeeman frequency shift C-field magnetic shielding
暂未订购 下载PDF
Effects of Second-Order Sum-and Difference-Frequency Wave Forces on the Motion Response of a Tension-Leg Platform Considering the Set-down Motion 认领 引用 被引量：3
20
作者 WANG Bin TANG Yougang +1 位作者 LI Yan CAI Runbo 《Journal of Ocean University of China》 SCIE CAS CSCD 2018年第2期311-319,共9页
This paper presents a study on the motion response of a tension-leg platform(TLP)under first-and second-order wave forces,including the mean-drift force,difference and sum-frequency forces.The second-order wave force ... This paper presents a study on the motion response of a tension-leg platform(TLP)under first-and second-order wave forces,including the mean-drift force,difference and sum-frequency forces.The second-order wave force is calculated using the full-field quadratic transfer function(QTF).The coupled effect of the horizontal motions,such as surge,sway and yaw motions,and the set-down motion are taken into consideration by the nonlinear restoring matrix.The time-domain analysis with 50-yr random sea state is performed.A comparison of the results of different case studies is made to assess the influence of second-order wave force on the motions of the platform.The analysis shows that the second-order wave force has a major impact on motions of the TLP.The second-order difference-frequency wave force has an obvious influence on the low-frequency motions of surge and sway,and also will induce a large set-down motion which is an important part of heave motion.Besides,the second-order sum-frequency force will induce a set of high-frequency motions of roll and pitch.However,little influence of second-order wave force is found on the yaw motion. 展开更多
关键词 tension-leg platform random wave second-order wave force quadratic transfer function sum-frequency difference-frequency set-down motion
暂未订购 下载PDF
已选0条
引用分析
参考文献
引证文献
 统计分析
检索结果
已选文献
上一页 1 2 … 250 下一页 到第 页
在线咨询 使用帮助 返回顶部 意见反馈