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STRONG CONVERGENCE OF THE EULER-MARUYAMA METHOD FOR A CLASS OF STOCHASTIC VOLTERRA INTEGRAL EQUATIONS

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Journal of Computational Mathematics 2022年第4期40卷 607-623页

作者： wei Zhang School of Mathematical Sciences Heilongjiang UniversityHarbin 150080China

In this paper,we consider the Euler-Maruyama method for a class of stochastic Volterra integral equations(SVIEs).It is known that the strong convergence order of the EulerMaruyama method is 12.However,the strong superconvergence order 1 can be obtained for a class of SVIEs if the kernelsσi(t,t)=0 for i=1 and 2;otherwise,the strong convergence order is 12.Moreover,the theoretical results are illustrated by some numerical examples.

关键词： Strong convergence Stochastic Volterra integral equations Euler-Maruyama method Lipschitz condition

Myelin-associated glycoprotein combined with chitin conduit inhibits painful neuroma formation after sciatic nerve transection

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Neural Regeneration Research 2022年第6期17卷 1343-1347页

作者： wei Pi Ci Li Meng zhang wei Zhang Pei-Xun zhang Department of Orthopedics and Trauma Peking University People’s HospitalPeking UniversityBeijingChina Key Laboratory of Trauma and Neural Regeneration Peking UniversityBeijingChina National Center for Trauma Medicine BeijingChina

Studies have shown that myelin-associated glycoprotein(MAG)can inhibit axon regeneration after nerve injury.However,the effects of MAG on neuroma formation after peripheral nerve injury remain poorly understood.In this study,local injection of MAG combined with nerve cap made of chitin conduit was used to intervene with the formation of painful neuroma after sciatic nerve transfection in rats.After 8 weeks of combined treatment,the autotomy behaviors were reduced in rats subjected to sciatic nerve transfection,the mRNA expression of nerve growth factor,a pain marker,in the proximal nerve stump was decreased,the density of regenerated axons was decreased,the thickness of the myelin sheath was increased,and the ratio of unmyelinated to myelinated axons was reduced.Moereover,the percentage of collagen fiber area and the percentage of fibrosis marker alpha-smooth muscle actin positive staining area in the proximal nerve stump were decreased.The combined treatment exhibited superior effects in these measures to chitin conduit treatment alone.These findings suggest that MAG combined with chitin conduit synergistically inhibits the formation of painful neuroma after sciatic nerve transection and alleviates neuropathic pain.This study was approved by the Animal Ethics Committee of Peking University People’s Hospital(approval No.2019PHE027)on December 5,2019.

关键词： autotomy axon chitin conduit fibrosis myelin-associated glycoprotein painful neuroma peripheral nerve regeneration

Fine-tuning cell organelle dynamics during mitosis by small GTPases

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Frontiers of Medicine 2022年第3期16卷 339-357页

作者： Zijian zhang wei Zhang Quentin Liu Sun Yat-sen University Cancer Center State Key Laboratory of Oncology in South ChinaCollaborative Innovation Center for Cancer MedicineGuangzhou 510060China Department of Clinical Immunology The Third Affiliated HospitalSun Yat-sen UniversityGuangzhou 510630China Institute of Cancer Stem Cell Dalian Medical UniversityDalian 116044China

During mitosis,the allocation of genetic material concurs with organelle transformation and distribution.The coordination of genetic material inheritance with organelle dynamics directs accurate mitotic progression,cell fate determination,and organismal homeostasis.Small GTPases belonging to the Ras superfamily regulate various cell organelles during division.Being the key regulators of membrane dynamics,the dysregulation of small GTPases is widely associated with cell organelle disruption in neoplastic and non-neoplastic diseases,such as cancer and Alzheimer’s disease.Recent discoveries shed light on the molecular properties of small GTPases as sophisticated modulators of a remarkably complex and perfect adaptors for rapid structure reformation.This review collects current knowledge on small GTPases in the regulation of cell organelles during mitosis and highlights the mediator role of small GTPase in transducing cell cycle signaling to organelle dynamics during mitosis.

关键词： small GTPase cell organelle mitosis

Vertical vibration control using nonlinear energy sink with inertial amplifier

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应用数学和力学:英文版 2023年第10期44卷 1721-1738页

作者： weixing zhang wei Zhang Xiangying GUO Faculty of Materials and Manufacturing Beijing University of TechnologyBeijing 100124China Beijing Key Laboratory of Nonlinear Vibrations and Strength of Mechanical Structures Beijing 100124China

To reduce additional mass, this work proposes a nonlinear energy sink(NES)with an inertial amplifier(NES-IA) to control the vertical vibration of the objects under harmonic and shock excitations. Moreover, this paper constructs pure nonlinear stiffness without neglecting the gravity effect of the oscillator. Both analytical and numerical methods are used to evaluate the performance of the NES-IA. The research findings indicate that even if the actual mass is 1% of the main oscillator, the NES-IA with proper inertia angles and mass distribution ratios can still effectively attenuate the steady-state and transient responses of the main oscillator. Nonlinear stiffness and damping also have important effects. Due to strongly nonlinear factors, the coupled system may exhibit higher branch responses under harmonic excitation. In shock excitation environment, the NES-IA with a large dynamic mass can trigger energy capture of both main resonance and high-frequency resonance. Furthermore, the comparison with the traditional NES also confirms the advantages of the NES-IA in overcoming mass dependence.

关键词： nonlinear energy sink(NES) vibration reduction inertial amplifier(IA) higher branch response high-frequency resonance

Light field super-resolution using complementary-view feature attention

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Computational Visual Media 2023年第4期9卷 843-858页

作者： wei Zhang wei Ke Da Yang Hao Sheng zhang Xiong Faculty of Applied Sciences Macao Polytechnic UniversityMacao SAR 999078China State Key Laboratory of Software Development Environment School of Computer Science and EngineeringBeihang UniversityBeijing 100191Chinaand Beihang Hangzhou Innovation Institute YuhangXixi Octagon CityYuhang DistrictHangzhou 310023China

Light field(LF)cameras record multiple perspectives by a sparse sampling of real scenes,and these perspectives provide complementary information.This information is beneficial to LF super-resolution(LFSR).Compared with traditional single-image super-resolution,LF can exploit parallax structure and perspective correlation among different LF views.Furthermore,the performance of existing methods are limited as they fail to deeply explore the complementary information across LF views.In this paper,we propose a novel network,called the light field complementary-view feature attention network(LF-CFANet),to improve LFSR by dynamically learning the complementary information in LF views.Specifically,we design a residual complementary-view spatial and channel attention module(RCSCAM)to effectively interact with complementary information between complementary views.Moreover,RCSCAM captures the relationships between different channels,and it is able to generate informative features for reconstructing LF images while ignoring redundant information.Then,a maximum-difference information supplementary branch(MDISB)is used to supplement information from the maximum-difference angular positions based on the geometric structure of LF images.This branch also can guide the process of reconstruction.Experimental results on both synthetic and real-world datasets demonstrate the superiority of our method.The proposed LF-CFANet has a more advanced reconstruction performance that displays faithful details with higher SR accuracy than state-of-the-art methods.

关键词： light field(LF) super-resolution(SR) attention

Level density of odd-A nuclei at saddle point

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Nuclear Science and Techniques 2023年第8期34卷 164-173页

作者： wei Zhang wei Gao Gui-Tao zhang Zhi-Yuan Li School of Physics and Microelectronics Zhengzhou UniversityZhengzhou 450001China

Based on the covariant density functional theory,by employing the core–quasiparticle coupling(CQC)model,the nuclear level density of odd-A nuclei at the saddle point is achieved.The total level density is calculated via the convolution of the intrinsic level density and the collective level density.The intrinsic level densities are obtained in the finite-temperature covariant density functional theory,which takes into account the nuclear deformation and pairing self-consistently.For saddle points on the free energy surface in the(β_(2),γ)plane,the entropy and the associated intrinsic level density are compared with those of the global minima.By introducing a quasiparticle to the two neighboring even–even core nuclei,whose properties are determined by the five-dimensional collective Hamiltonian model,the collective levels of the odd-A nuclei are obtained via the CQC model.The total level densities of the^(234-240)U agree well with the available experimental data and Hilaire’s result.Furthermore,the ratio of the total level densities at the saddle points to those at the global minima and the ratio of the total level densities to the intrinsic level densities are discussed separately.

关键词： Level density Covariant density functional theory Core–quasiparticle coupling model Saddle point

Deep Learning-Based Radio Map for MIMO-OFDM Downlink Precoding

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Journal of Communications and Information Networks 2023年第3期8卷 203-211页

作者： wei Wang Bin Yang wei Zhang Peng Cheng Laboratory Shenzhen 518055China The School of Electrical Engineering and Telecommunications the University of New South WalesSydneyNSW 2052Australia

Radio map is an advanced technology that mitigates the reliance of multiple-input multiple-output(MIMO)beamforming on channel state information(CSI).In this paper,we introduce the concept of deep learning-based radio map,which is designed to be generated directly from the raw CSI data.In accordance with the conventional CSI acquisition mechanism of MIMO,we first introduce two baseline schemes of radio map,i.e.,CSI prediction-based radio map and throughput predictionbased radio map.To fully leverage the powerful inference capability of deep neural networks,we further propose the end-to-end structure that outputs the beamforming vector directly from the location information.The rationale behind the proposed end-to-end structure is to design the neural network using a task-oriented approach,which is achieved by customizing the loss function that quantifies the communication quality.Numerical results show the superiority of the task-oriented design and confirm the potential of deep learning-based radio map in replacing CSI with location information.

关键词： radio map deep learning MIMO taskoriented approach

Mechanical,expansion and rheological properties of circulating fluidized bed fly ash based ecological cement:A critical review

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International Journal of Minerals,Metallurgy and Materials 2022年第9期29卷 1670-1682页

作者： wei Zhang Xiaoming Liu Zengqi zhang State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China

Circulating fluidized bed fly ash(CFBFA)is a solid waste product from circulating fluidized bed(CFB)boilers in power plants,and the storage of CFBFA is increasingly become an environmental problem.Previous scholars have made contributions to improve the resource utilization of CFBFA.Especially,ecological cement is prepared by CFBFA,which is more conducive to its large-scale utilization.In recent years,a lot of effort has been paid to improve the properties of ecological cement containing CFBFA.In this work,the physicochemical properties of CFBFA are introduced,and recent research progress on the mechanical,expansion,and rheological properties of CFBFA based ecological cement(CEC)is extensively reviewed.The problem of over-expansion of f-CaO is summarized,which limits the scale application of CFBFA in ecological cement.Hence,the challenge for f-CaO in CFBFA to compensate for cement volume shrinkage is proposed,which is beneficial to the utilization of CFBFA in ecological cement,and the reduction of CO_(2) emissions from the cement industry.In addition,the environmental performance,durability,and economy of CEC should be valued in future research,especially the environmental performance,because the CFBFA contains heavy metals,such as Cr,As,which may pollute groundwater.

关键词： circulating fluidized bed fly ash ecological cement expansion durability compensation shrinkage

Experimentally Ruling Out Joint Reality Based on Locality with Device-Independent Steering

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Chinese Physics Letters 2024年第1期41卷 1-5页

作者： Shuaining zhang Xiang zhang Zhiyue Zheng wei Zhang Beijing Academy of Quantum Information Sciences Beijing 100193China Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano Devices Renmin University of ChinaBeijing 100872China Key Laboratory of Quantum State Construction and Manipulation(Ministry of Education) Renmin University of ChinaBeijing 100872China

As an essential concept to understand the world,whether the real values(or physical realities)of observables are suitable to physical systems beyond the classic has been debated for many decades.Although standard nogo results based on Bell inequalities have ruled out the joint reality of incompatible quantum observables,the possibility of giving simple yet strong arguments to rule out joint reality in any physical system(not necessarily quantum)with weaker assumptions and less observables has been explored and proposed recently.Here,we perform a device-independent experiment on a two-qubit superconducting system to show that the joint reality of two observables is incompatible with locality under the weaker assumption of the reality of observables in a single space-time region(or single qubit).Our results clearly show the violation of certain inequalities derived from both linear and nonlinear criteria.In addition,we study the robustness of the linear and nonlinear criterion against the effect of systematic decoherence.Our demonstration opens up the possibility of delineating classical and non-classical boundaries with simpler nontrivial quantum system.

关键词： observable quantum system