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Orientation of LDPE Crystals from Microscale to Nanoscale via Microlayer or Nanolayer Coextrusion

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Chinese Journal of Polymer Science 2016年第12期34卷 1411-1411,1412-1422页

作者： Jun-feng cheng 浦鸿汀 School of Materials Science and Engineering Tongji University

Abstract The microlayer or nanolayer coextrusion of hundreds or thousands of alternating low density polyethylene （LDPE）/polystyrene （PS） microlayers or nanolayers were used to study the orientation of LDPE crystals in the confined quasi-two-dimensional or two-dimensional space. The clear and continuous layer structures from microscale to nanoscale can be found in SEM images. The morphology evolution of LDPE crystals in the confined microlayer or nanolayer can he varied from 3D spherulites, 2D spherulites, stacked edge-on lamellar, to single edge-on lamellar. Due to the orientation of the LDPE crystals, the tensile strength of the films increases obviously when the layer thickness reduces to nanoscale. The 2D small angle X-ray scattering （SAXS） patterns can reflect the average degree of orientation of LDPE in the confined layers. The stacking of LDPE lamellae is suppressed in interlamination and oppositely in parallel to the extrusion direction. The specific orientation function f can be calculated from the patterns. The infrared dichroism further confirms the mutation of the orientation of LDPE crystals from microscale to nanoscale in the confined space.

关键词： Microlayer or nanolayer coextrusion Low density polyethylene Polystyrene Confined space Crystalorientation.

Prediction of electric-powered fixed-wing UAV endurance

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航空动力学报 2017年第9期32卷 2170-2179页

作者： cheng feng WANG Hua CUI Pin School of Astronautics Beijing University of Aeronautics and Astronautics Science and Technology on Space Physics Laboratory China Academy of Launch Vehicle Technology

To overcome the problems encountered in predicting the endurance of electricpowered fixed-wing unmanned aerial vehicles(UAVs),which were stemmed from the dynamic changes in electric power system efficiency and battery discharge characteristics under different operating conditions,the required battery power model and battery discharge model were *** required battery power model was determined using an approximate model of electric power system efficiency based on wind tunnel testing and the self-adaptive penalty ***,current correction and ambient temperature correction terms were proposed for the trained Kriging model representing the discharge characteristics under standard operation,and then the discharged capacity-terminal voltage model was *** numerical integration of this model with the required battery power model,the electric-powered fixed-wing UAV endurance prediction model was *** tests indicated that the proposed endurance model could precisely calculate the battery discharge time and accurately describe the battery discharge *** similarity of the theoretical and flight test results reflected the accuracy of the proposed endurance model as well as the importance of considering dynamic changes in power system efficiency in endurance *** proposed endurance model meeting precision requirements can be used in practical engineering applications.

关键词： fixed-wing unmanned aerial vehicle(UAV) endurance Peukert equation self-adaptive penalty function power system efficiency

Rotorcraft flight endurance estimation based on a new battery discharge model

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Chinese Journal of Aeronautics 2017年第4期30卷 1561-1569页

作者： feng cheng Hua WANG Pin CUI School of Astronautics Beihang University Beijing 100083 China Science and Technology on Space Physics Laboratory Beijing 100076 China

To avoid the numerical complexities of the battery discharge law of electric-powered rotorcrafts,this study uses the Kriging method to model the discharge characteristics of Li-Po batteries under standard conditions.A linear current compensation term and an ambient temperature compensation term based on radial basis functions are then applied to the trained Kriging model,leading to the complete discharged capacity-terminal voltage *** an orthogonal experimental design and a sequential method,the coefficients of the current and ambient temperature compensation terms are determined through robust *** endurance calculation model for electric-powered rotorcrafts is then established,based on the battery discharge model,through numerical *** tests show that the maximum relative error of the proposed discharged capacity-terminal voltage model at detection points is 0.0086,and that of the rotorcraft endurance calculation model is 0.0195,thus verifying their accuracy.A flight test further demonstrates the applicability of the proposed endurance model to general electric-powered rotorcrafts.

关键词： Kriging model Orthogonal experimental design Robust optimization Rotorcraft endurance Sequential method

SET COVERING-BASED TOPSIS METHOD FOR SLOVING SUP-T EQUATION CONSTRAINED MULTI-OBJECTIVE OPTIMIZATION PROBLEMS

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Journal of Systems Science and Systems Engineering 2015年第3期24卷 258-275页

作者： cheng-feng Hu Shu-Cherng Fang Department of Applied Mathematics National Chaiyi University Edward P.Fitts Department of Industrial and Systems Engineering North Carolina State University

This paper considers solving a multi-objective optimization problem with sup-T equation constraints A set covering-based technique for order of preference by similarity to the ideal solution is proposed for solving such a problem. It is shown that a compromise solution of the sup-T equation constrained multi-objective optimization problem can be obtained by ＂solving an associated set covering problem. A surrogate heuristic is then applied to solve the resulting optimization problem. Numerical experiments on solving randomly generated multi-objective optimization problems with sup-T equation constraints are included. Our computational results confirm the efficiency of the proposed method and show its potential for solving large scale sup-T equation constrained multi-objective optimization problems.

关键词： Fuzzy relational equations fuzzy optimization set covering problems

Quasiprobability Distribution of Squeezed Thermal Spin States in Ferromagnet

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Communications in Theoretical Physics 2008年第3期49卷 777-782页

作者： XU Qin-feng cheng Ze Department of Physics Huazhong University of Science and Technology Wuhan 430074 China

We study squeezed properties of magnon squeezed thermal spin states by using the distribution of Q function in the ferromagnet. It is found that the distribution of Q function strongly depends on the temperature T and coupling parameter γ. Below the transition temperature Tc, the distribution Q function in the squeezed thermal spin state presents a richer structure than in the normal state. Non-classical effects have been observed. In the transition from the normal to the squeezed thermal spin state, the phase symmetry of the magnon system is spontaneously broken.

关键词： squeezed thermal spin state ferromagnon quasiprobability distribution function

Learning robust principal components from L1-norm maximization

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Journal of Zhejiang University-Science C(Computers and Electronics) 2012年第12期13卷 901-908页

作者： Ding-cheng feng feng CHEN Wen-li XU Tsinghua National Laboratory for Information Science and Technology Tsinghua University Beijing 100084 China Department of Automation Tsinghua University Beijing 100084 China

Principal component analysis(PCA) is fundamental in many pattern recognition *** research has been performed to minimize the reconstruction error in L1-norm based reconstruction error minimization(L1-PCA-REM) since conventional L2-norm based PCA(L2-PCA) is sensitive to ***,the variance maximization formulation of PCA with L1-norm(L1-PCA-VM) has been proposed,where new greedy and nongreedy solutions are *** with the gradient ascent perspective for optimization,we show that the L1-PCA-VM formulation is problematic in learning principal components and that only a greedy solution can achieve robustness motivation,which are verified by experiments on synthetic and real-world datasets.

关键词： Principal component analysis(PCA) Outliers L1-norm,Greedy algorithms Non-greedy algorithms

Coarse-fine joint target parameter estimation method based on AN-RSC in OFDM passive radar

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Journal of Systems Engineering and Electronics 2024年第2期35卷 339-349页

作者： WANG Chujun WAN Xianrong YI Jianxin cheng feng School of Electronic Information Wuhan UniversityWuhan 430072China

In this paper,we study the accuracy of delay-Doppler parameter estimation of targets in a passive radar using orthogonal frequency division multiplexing(OFDM)signal.A coarse-fine joint estimation method is proposed to achieve better estimation accuracy of target parameters without excessive computational ***,the modulation symbol domain(MSD)method is used to roughly estimate the delay and Doppler of ***,to obtain high-precision Doppler estimation,the atomic norm(AN)based on the multiple measurement vectors(MMV)model(MMV-AN)is used to manifest the signal sparsity in the continuous Doppler *** the same time,a reference signal compensation(RSC)method is presented to obtain highprecision delay *** results based on the OFDM signal show that the coarse-fine joint estimation method based on AN-RSC can obtain a more accurate estimation of target parameters compared with other *** addition,the proposed method also possesses computational advantages compared with the joint parameter estimation.

关键词： passive radar orthogonal frequency division multiplexing(OFDM)signal atomic norm(AN) parameter estimation

Squeezing States of Magnons in a Ferromagnet

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Communications in Theoretical Physics 2006年第4期45卷 745-748页

作者： WANG Jun-feng cheng Ze Department of Physics Huazhong University of Science and Technology Wuhan 430074 China

In this paper, we conduct an investigation into magnon self-squeezing states in a ferromagnet. In these states, the quantum fluctuations of the spin components can be lower than the zero-point quantum fluctuations of the coherent states. Through calculating the expectation values of spin fluctuations we gain the condition of achieving magnon self-squeezing. We introduce the mean-field theory for dealing with the nonlinear interaction term of Hamiltonian of magnon system.

关键词： self-squeezing state spin wave magnon quantum fluctuation

DTHN: Dual-Transformer Head End-to-End Person Search Network

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Computers, Materials & Continua 2023年第10期77卷 245-261页

作者： cheng feng Dezhi Han Chongqing Chen School of Information Engineering Shanghai Maritime UniversityShanghai201306China

Person search mainly consists of two submissions,namely Person Detection and Person Re-identification(reID).Existing approaches are primarily based on Faster R-CNN and Convolutional Neural Network(CNN)(e.g.,ResNet).While these structures may detect high-quality bounding boxes,they seem to degrade the performance of *** address this issue,this paper proposes a Dual-Transformer Head Network(DTHN)for end-to-end person search,which contains two independent Transformer heads,a box head for detecting the bounding box and extracting efficient bounding box feature,and a re-ID head for capturing high-quality re-ID features for the re-ID ***,after the image goes through the ResNet backbone network to extract features,the Region Proposal Network(RPN)proposes possible bounding *** box head then extracts more efficient features within these bounding boxes for *** this,the re-ID head computes the occluded attention of the features in these bounding boxes and distinguishes them from other persons or *** experiments on two widely used benchmark datasets,CUHK-SYSU and PRW,achieve state-of-the-art performance levels,94.9 mAP and 95.3 top-1 scores on the CUHK-SYSU dataset,and 51.6 mAP and 87.6 top-1 scores on the PRW dataset,which demonstrates the advantages of this paper’s *** efficiency comparison also shows our method is highly efficient in both time and space.

关键词： Transformer occluded attention end-to-end person search person detection person re-ID Dual-Transformer Head