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A Novel CCA-NMF Whitening Method for Practical Machine Learning Based Underwater Direction of Arrival Estimation

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Journal of Beijing Institute of Technology 2024年第2期33卷 163-174页

作者： Yun Wu Xinting Li zhimin.Cao School of Physics and Electronic Engineering Northeast Petroleum UniversityDaqing 163318China

Underwater direction of arrival(DOA)estimation has always been a very challenging theoretical and practical *** to the serious non-stationary,non-linear,and non-Gaussian characteristics,machine learning based DOA estimation methods trained on simulated Gaussian noised array data cannot be directly applied to actual underwater DOA estimation *** order to deal with this problem,environmental data with no target echoes can be employed to analyze the non-Gaussian ***,the obtained information about non-Gaussian components can be used to whiten the array *** on these considerations,a novel practical sonar array whitening method was ***,based on a weak assumption that the non-Gaussian components in adjacent patche. with and without target echoes are almost the same,canonical cor-relation analysis(CCA)and non-negative matrix factorization(NMF)techniques are employed for whitening the array *** the whitened array data,machine learning based DOA estimation models trained on simulated Gaussian noised datasets can be used to perform underwater DOA estimation *** results illustrated that,using actual underwater datasets for testing with known machine learning based DOA estimation models,accurate and robust DOA estimation performance can be achieved by using the proposed whitening method in different underwater con-ditions.

关键词： direction of arrival(DOA) sonar array data underwater disturbance machine learn-ing canonical correlation analysis(CCA) non-negative matrix factorization(NMF)

Surrounding rock pressure in the tunnel portal section through moraine under freeze-thaw action

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Journal of Mountain Science 2024年第7期21卷 2480-2493页

作者： che. zhimin.LIU Baoli LIU Yaohui XU Jiangtao School of Civil Engineering Lanzhou Jiaotong UniversityLanzhou 730070China CSCEC AECOM Consultants Co. ltdLanzhou 730000China National and Local Joint Engineering Laboratory of Road and Bridge Engineering Disaster Prevention Technology Lanzhou Jiaotong UniversityLanzhou 730070China

Moraines,characterized by the accumulation of rock and soil debris transported by glacial activity,present unique challenges for tunnel construction,particularly in portal sections,due to prevailing geographical and climatic conditions that facilitate freeze-thaw *** these challenges,there is a dearth of studies investigating the influence of freeze-thaw action and water content on the mechanical properties of moraines,and no research on calculating surrounding rock pressure in moraine tunnels subjected to freeze-thaw *** this study,direct shear tests under freeze-thaw cycles were conducted to examine the effects of freeze-thaw cycles and water content on the mechanical properties of frozen moraine.A comprehensive parameter K,integrating the number of freeze-thaws and water content,was introduced to model cohesion *** on Terzaghi Theory,we propose an improved algorithm for calculating surrounding rock pressure at the portal section of moraine *** a tunnel as a case study,surrounding rock pressure was calculated under various conditions to validate the Improved Algorithm's *** results show that:(1)Strength loss exhibits a linear trend with the number of freeze-thaw cycles at water content levels of 4%and 8%,while at 12%water content,previous freeze-thaw cycles induce more significant damage to the soil.(2)Moraine saturation peaks between 8%and 12%water *** repeated freeze-thaw cycles,moraine shear strength initially increases before decreasing with varying water content.(3)The internal friction angle of moraine experiences slight reductions with prolonged freeze-thaw cycles,but both freeze-thaw cycles and water content significantly influence cohesion.(4)Vertical surrounding rock pressure increases after the initial freeze-thaw cycle,particularly with higher water content,although freeze-thaw cycles have minimal effect on it.(5)Freeze-thaw cycles lead to a substantial increase in lateral surrounding rock pre

关键词： Moraines Freeze-thaw cycles Direct shear test Surrounding rock pressure

Formulation,characterization and in vivo and in vitro evaluation of aloe-emodin-loaded solid dispersions for dissolution enhancement

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Journal of Traditional Chinese Medicine 2024年第1期44卷 54-62页

作者： LI Xiuyan LUO Yuting WANG Jinhui DU zhimin Key Laboratory of Basic and Application Research of Beiyao Heilongjiang University of Chinese MedicineMinistry of EducationHarbin 150040China College of Pharmacy Harbin Medical UniversityHarbin 150081China Institute of Clinical Pharmacology the Second Affliated Hospital of Harbin Medical University(University Key aboratory of Drug ResearchHeilongjiang Province)Harbin 150086China Department of Clinical Pharmacology College of Pharmacy Harbin Medical UniversityHarbin 150081China State Key Laboratory of Quality Research in Chinese Medicines Macao University of Science and TechnologyMacao 999078China

OBJECTIVE:To prepare aloe-emodin solid dispersion(AE-SD)and determine the metabolic process of AE and AE-SD in ***:AE-SD was prepared via solvent evaporation or solvent melting using PEG-6000 and PVP-K30 as *** analysis,X-ray diffraction spectroscopy,differential scanning calorimetry,Fourier transform infrared spectroscopy and scanning electron microscopy were used to identify the physical state of *** prescriptions were screened via the dissolution degree determination *** Phoenix software,AE suspension and AE-SD were subjected to a pharmacokinetic comparison study analyzing the alteration of behavior in vivo after AE was prepared as a solid *** toxicity was assessed in mice,and the physiological toxicity was used as the determination criterion for ***:AE-SD showed that AE existed in the carrier in an amorphous *** with polyethylene glycol,polyvinylpyrrolidone(PVP)inhibited AE crystallization,causing the drug to transform from a dense crystalline state to an amorphous form and increasing the degree of drug ***,it was more suitable as a carrier material for *** addition of poloxamer(POL)was more beneficial to the stability of solid dispersions and could reduce the amount of *** dissolution test confirmed that the optimal ratio of AE to the composite vector AE-PVP-POL was 1:2:2,and its dissolution effect was also *** on the pharmacokinetic comparison,the drug absorption was faster and quickly reache. the peak of blood drug concentration in AE-SD compared to AE,the Cmax of AE-SD was greater than that of AE,and t1/2 and mean residence time of AE-SD were less than *** results showed that the drug metabolism in AE-SD was better,and the residence time was *** toxicology study showed that both AE and AE-SD had no ***:This paper established that the solubility of the drug could be increased after preparing a solid dispersion,

关键词： aloe-emodin solid dispersion solvent evaporation drug liberation pharmacokinetics

Seed-assisted growth for high-performance perovskite solar cells:A review

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Journal of Energy che.istry 2024年第9期96卷 588-610页

作者： zhimin.Fang Ting Nie Jianning Ding Shengzhong(Frank)Liu Institute of Technology for Carbon Neutralization Yangzhou UniversityYangzhou 225127JiangsuChina Dalian National Laboratory for Clean Energy iChEMDalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina Key Laboratory of Applied Surface and Colloid che.istry Ministry of EducationShaanxi Key Laboratory for Advanced Energy DevicesShaanxi Engineering Lab for Advanced Energy TechnologySchool of Materials Science and EngineeringShaanxi Normal UniversityXi’an 710119ShaanxiChina

The rapid increase in the power conversion efficiency(PCE)of perovskite solar cells(PSCs)is closely related to the development of deposition techinique for perovskite *** high-quality perovskite film enables efficient charge transportation and less trap states,which are eventually translated into enhanced device ***-assisted growth(SAG)is a potential technique for depositing highly-crystallized perovskite films with preferential crystal orientation among the numerous approache. related to crystallization *** this review,we summarize the recent advances in the SAG technique for both one-step and two-step processed perovskite ***,seeding at the buried interface and on the top surface are also *** present different seeds and their corresponding seeding mechanism in detail,such as inorganic nanomaterials,organic ammoniums,alkali metal halides,and perovskite ***,challenges and perspectives are proposed to investigate the potential expansion of seeding engineering in high-performance PSCs,particularly large-area devices.

关键词： Perovskite solar cell Seed Crystallization Efficiency

VARIABLE STEP-SIZE BDF3 METHOD FOR ALLEN-CAHN EQUATION

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Journal of Computational Mathematics 2024年第5期42卷 1380-1406页

作者： Minghua che. Fan Yu Qingdong Zhang zhimin.Zhang School of Mathematics and Statistics Gansu Key Laboratory of Applied Mathematics and Complex SystemsLanzhou UniversityLanzhou 730000China Department of Mathematics Wayne State UniversityDetroitMI 48202USA

In this work,we analyze the three-step backward differentiation formula(BDF3)method for solving the Allen-Cahn equation on variable *** BDF2 method,the discrete orthogonal convolution(DOC)kernels are positive,the stability and convergence analysis are well established in[Liao and Zhang,***.,90(2021),1207–1226]and[che.,Yu,and Zhang,arXiv:2108.02910,2021].However,the numerical analysis for BDF3 method with variable steps seems to be highly nontrivial due to the additional degrees of freedom and the non-positivity of DOC *** developing a novel spectral norm inequality,the unconditional stability and convergence are rigorously proved under the updated step ratio restriction rk:=τk/τk−1≤1.405 for BDF3 ***,numerical experiments are performed to illustrate the theoretical *** the best of our knowledge,this is the first theoretical analysis of variable steps BDF3 method for the Allen-Cahn equation.

关键词： Variable step-size BDF3 method Allen-Cahn equation Spectral norm inequality Stability and convergence analysis

Orthogonal waveform design with fractional programming on the ambiguity suppression of SAR systems

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Science China(Information Sciences) 2024年第9期67卷 263-279页

作者： Yunkai DENG Yongwei ZHANG zhimin.ZHANG Wei WANG Heng ZHANG Department of Space Microwave Remote Sensing System Aerospace Information Research InstituteChinese Academy of Sciences

Waveform diversity(WD) represents a dynamic and transformative technology widely used in radar systems to enhance sensitivity and discrimination capabilities. Recently, WD techniques have been extensively explored for their potential ambiguity suppression within synthetic aperture radar(SAR) *** these, the alternate transmitting mode combined with orthogonal waveforms emerges as a particularly promising solution. This study focuses on optimizing the power spectrum density(PSD) of signals to design and generate an orthogonal waveform pair that achieves both a low cross-correlation-to-autocorrelation ratio(CAR) and satisfactory imaging performance. Initially, we construct a fractional programming model with convex constraints to minimize the CAR. To address this challenge, we introduce an iterative optimization procedure for the PSD variable, which sequentially reduces the CAR. Each optimization step can be efficiently solved using a quadratically constrained quadratic program, ensuring that the resulting computational complexity remains low. Building on the optimized PSD, we established a parametric piecewise linear model to generate an orthogonal waveform pair. This model not only maintains a low CAR but achieves satisfactory imaging performance in real-time applications. Consequently, this orthogonal waveform pair effectively suppresses range ambiguity in SAR systems. Finally, we demonstrated the practicability and effectiveness of the proposed orthogonal waveforms through detailed simulation experiments, specifically targeting ambiguity suppression in conventional quad-polarization SAR systems.

关键词： synthetic aperture radar (SAR) waveform diversity (WD) ambiguity suppression orthogonal waveform fractional programming power spectrum density (PSD)

EFFICIENT SPECTRAL METHODS FOR EIGENVALUE PROBLEMS OF THE INTEGRAL FRACTIONAL LAPLACIAN ONABALLOFANYDIMENSION

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Journal of Computational Mathematics 2024年第4期42卷 1032-1062页

作者： Suna Ma Huiyuan Li zhimin.Zhang Hu che. Lizhen che. College of Science Nanjing University of Posts and TelecommunicationsNanjingChina State Key Laboratory of Computer Science/Laboratory of Parallel Computing Institute of SoftwareChinese Academy of SciencesBeijingChina Department of Mathematics Wayne State UniversityDetroitUSA School of Mathematical Sciences Ocean University of ChinaQingdaoChina Beijing Computational Science Research Center BeijingChina

An efficient spectral-Galerkin method for eigenvalue problems of the integral fractional Laplacian on a unit ball of any dimension is proposed in this *** symmetric positive definite linear system is retained explicitly which plays an important role in the numerical *** a sharp estimate on the algebraic system's condition number is established which behaves as N4s with respect to the polynomial degree N,where 2s is the fractional derivative *** regularity estimate of solutions to source problems of the fractional Laplacian in arbitrary dimensions is firstly investigated in weighted Sobolev *** the regularity of eigenfunctions of the fractional Laplacian eigenvalue problem is readily ***,rigorous error estimates of the eigenvalues and eigenvectors are *** experiments are presented to demonstrate the accuracy and efficiency and to validate the theoretical results.

关键词： Integral fractional Laplacian Spectral method Eigenvalue problem Regularity analysis Error estimate

Artificial intelligence in physiological characteristics recognition for internet of things authentication

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Digital Communications and Networks 2024年第3期10卷 740-755页

作者： zhimin.Zhang Huansheng Ning Fadi Farha Jianguo Ding Kim-Kwang Raymond Choo School of Computer and Communication Engineering University of Science and Technology BeijingBeijing100083China Beijing Engineering Research Center for Cyberspace Data Analysis and Applications Beijing100083China Faculty of Informatics Engineering Aleppo UniversityAleppoSyria Department of Computer Science Blekinge Institute of Technology37179KarlskronaSweden Department of Information Systems and Cyber Security University of Texas at San AntonioSan AntonioTX78249-0631USA

Effective user authentication is key to ensuring equipment security,data privacy,and personalized services in Internet of Things(IoT)***,conventional mode-based authentication methods(e.g.,passwords and smart cards)may be vulnerable to a broad range of attacks(e.g.,eavesdropping and side-channel attacks).Hence,there have been attempts to design biometric-based authentication solutions,which rely on physiological and behavioral *** characteristics need continuous monitoring and specific environmental settings,which can be challenging to implement in ***,we can also leverage Artificial Intelligence(AI)in the extraction and classification of physiological characteristics from IoT devices processing to facilitate ***,we review the literature on the use of AI in physiological characteristics recognition pub-lished after *** use the three-layer architecture of the IoT(i.e.,sensing layer,feature layer,and algorithm layer)to guide the discussion of existing approache. and their *** also identify a number of future research opportunities,which will hopefully guide the design of next generation solutions.

关键词： Physiological characteristics recognition Artificial intelligence Internet of things Biological-driven authentication

Optimizing piezoelectric performance of complex perovskite through increasing diversity of B-site cations

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Journal of Materials Science & Technology 2024年第3期170卷 78-86页

作者： Mengdi che.g Dongyan Zhang Yangxi Yan zhimin.Li Pangpang Wang Ri-ichi Murakami School of Advanced Materials and Nanotechnology Xidian UniversityXi’an 710126China Nanomaterials Group Institute of SystemInformation Technologies and Nanotechnologies(ISIT)Fukuoka Industry-Academia Symphonicity(FiaS)4-1 KyudaishinmachiNishi-kuFukuoka 819-0388Japan School of Mechanical Engineering Chengdu UniversityChengdu 610106China

Piezoelectric materials with unique properties are hugely appealing for high sensitivity sensors and ultrasonic ***,Pb(Ni_(1/3)Nb_(2/3))O_(3)-Pb(Yb_(1/2)Nb_(1/2))O_(3)-PbTiO_(3)piezoelectric system was designed and investigated in *** optimized piezoelectric response(d_(33)=826 pC/N,d_(33)∗=1017 pm/V)together with good temperature stability and negligible performance degradation up to 10^(6) cycles was achieved in 0.58PNN-0.10PYN-0.32PT *** analysis revealed the amplification of intrinsic and extrinsic contributions in MPB region due to more spontaneous polarization orientations and an increase in che.ical disorder of system after the introduction of *** origin of high piezoelectric response was investigated through the combination of scanning electron microscopy and piezoresponse force *** diversity of B-site cations was shown to enhance local structural heterogeneity,weaken long-range ferroelectric ordered domains,and lower free energy barrier via the formation of nanodomain configuration that promoted polarization rotation,thereby improving piezoelectric properties of the ***,it is suggested that increasing the diversity of B-site cations is an effective strategy for achieving outstanding piezoelectric performance.

关键词： PNN-PYN-PT ceramics Piezoelectricity enhancement Relaxation behavior Domain structure