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Evaluation of freezing state of sandstone using ultrasonic time-frequency characteristics
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作者 jiwei zhang Julian Murton +4 位作者 Tim Cane Vikram Maji Lili Sui Shujie Liu Song zhang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第3期584-599,共16页
Common problems in engineering projects that involve artificial ground freezing of soil or rock include inadequate thickness,strength and continuity of artificial frozen walls.It is difficult to evaluate the freezing ... Common problems in engineering projects that involve artificial ground freezing of soil or rock include inadequate thickness,strength and continuity of artificial frozen walls.It is difficult to evaluate the freezing state using only a few thermometer holes at fixed positions or with other existing approaches.Here we report a novel experimental design that investigates changes in ultrasonic properties(received waveform,wave velocity V_(p),wave amplitude,frequency spectrum,centroid frequency f_(c),kurtosis of the frequency spectrum KFS,and quality factor Q)measured during upward freezing,compared with those during uniform freezing,in order to determine the freezing state in 150 mm cubic blocks of Ardingly sandstone.Water content,porosity and density were estimated during upward freezing to ascertain water migration and changes of porosity and density at different stages.The period of receiving the wave increased substantially and coda waves changed from loose to compact during both upward and uniform freezing.The trend of increasing V_(p) can be divided into three stages during uniform freezing.During upward freezing,V_(p) increased more or less uniformly.The frequency spectrum could be used as a convenient and rapid method to identify different freezing states of sandstone(unfrozen,upward frozen,and uniformly frozen).The continuous changes in reflection coefficient r_(φ),refraction coefficient t_(φ) and acoustic impedance field are the major reason for larger reflection and refraction during upward freezing compared with uniform freezing.Wave velocity V_(p),wave amplitude A_(h),centroid frequency f_(c) and quality factor Q were adopted as ultrasonic parameters to evaluate quantitatively the temperature T of uniformly frozen sandstone,and their application within a radar chart is recommended.Determination of V_(p) provides a convenient method to evaluate the freezing state and calculate the cryofront height and frozen section thickness of upward frozen sandstone,with accuracies of 73.37%-99.23%. 展开更多
关键词 Frozen sandstone Uniform freezing Upward freezing Ultrasonic testing Freezing state
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A New Partial Task Offloading Method in a Cooperation Mode under Multi-Constraints for Multi-UE
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作者 Shengyao Sun Ying Du +3 位作者 Jiajun Chen Xuan zhang jiwei zhang Yiyi Xu 《Computers, Materials & Continua》 SCIE EI 2023年第9期2879-2900,共22页
In Multi-access Edge Computing(MEC),to deal with multiple user equipment(UE)’s task offloading problem of parallel relationships under the multi-constraints,this paper proposes a cooperation partial task offloading m... In Multi-access Edge Computing(MEC),to deal with multiple user equipment(UE)’s task offloading problem of parallel relationships under the multi-constraints,this paper proposes a cooperation partial task offloading method(named CPMM),aiming to reduce UE’s energy and computation consumption,while meeting the task completion delay as much as possible.CPMM first studies the task offloading of single-UE and then considers the task offloading ofmulti-UE based on single-UE task offloading.CPMMuses the critical path algorithmto divide the modules into key and non-key modules.According to some constraints of UE-self when offloading tasks,it gives priority to non-key modules for offloading and uses the evaluation decision method to select some appropriate key modules for offloading.Based on fully considering the competition between multiple UEs for communication resources and MEC service resources,CPMM uses the weighted queuing method to alleviate the competition for communication resources and uses the branch decision algorithm to determine the location of module offloading by BS according to the MEC servers’resources.It achieves its goal by selecting reasonable modules to offload and using the cooperation ofUE,MEC,andCloudCenter to determine the execution location of themodules.Extensive experiments demonstrate that CPMM obtains superior performances in task computation consumption reducing around 6%on average,task completion delay reducing around 5%on average,and better task execution success rate than other similar methods. 展开更多
关键词 MEC partial task offloading parallel dependencies completion delay
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The rice miR171b–SCL6-IIs module controls blast resistance,grain yield,and flowering 被引量:1
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作者 Yan Li Ying Tong +12 位作者 Xiaorong He Yong Zhu Tingting Li Xiaoyu Lin Wei Mao Zeeshan Ghulam Nabi Gishkori Zhixue Zhao jiwei zhang Yanyan Huang Mei Pu Jing Fan Jing Wang Wenming Wang 《The Crop Journal》 SCIE CSCD 2022年第1期117-127,共11页
Micro RNAs(mi RNAs)act as regulators of plant development and multiple stress responses.Here we demonstrate that the rice mi R171 b-SCL6-IIs module regulates the balance between blast resistance,grain yield,and flower... Micro RNAs(mi RNAs)act as regulators of plant development and multiple stress responses.Here we demonstrate that the rice mi R171 b-SCL6-IIs module regulates the balance between blast resistance,grain yield,and flowering.mi R171 b-overexpressing rice plants(OX171 b)displayed increased rice blast resistance accompanied with enhanced defense responses and late heading,whereas blocking mi R171 b expression in rice(MIM171)led to greater susceptibility to blast disease,associated with compromised defense responses and early heading.Either overexpressing or silencing of mi R171 b significantly affected plant height and number of filled seeds per panicle(seed-setting rate),resulting in decreased grain yield.mi R171 b targets SCL6-IIa,SCL6-IIb,and SCL6-IIc,whose expression was suppressed in OX171 b but increased in MIM171.Mutants of SCL6-IIa,SCL6-IIb,and SCL6-IIc all displayed phenotypes like that of OX171 b,including markedly increased blast disease resistance,slightly decreased grain yield,and delayed flowering.Amounts of mi R171 b increased gradually in leaves during the vegetative stage but decreased gradually in panicles during the reproductive stage,whereas SCL6-IIs displayed the reverse expression pattern.Together,these results suggest that the expression of mi R171 b was time-and space-dependent during the rice growth period and regulated the balance between rice blast disease resistance,grain yield,and flowering via SCL6-IIs,and that appropriate accumulation of mi R171 b is essential for rice development. 展开更多
关键词 miR171b SCL6-IIs Blast disease resistance Yield trait FLOWERING
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Numerical Computations of Nonlocal Schrodinger Equations on the Real Line 被引量:1
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作者 Yonggui Yan jiwei zhang Chunxiong Zheng 《Communications on Applied Mathematics and Computation》 2020年第2期241-260,共20页
The numerical computation of nonlocal Schrödinger equations (SEs) on the whole real axis is considered. Based on the artifcial boundary method, we frst derive the exact artifcial nonrefecting boundary conditions.... The numerical computation of nonlocal Schrödinger equations (SEs) on the whole real axis is considered. Based on the artifcial boundary method, we frst derive the exact artifcial nonrefecting boundary conditions. For the numerical implementation, we employ the quadrature scheme proposed in Tian and Du (SIAM J Numer Anal 51:3458-3482, 2013) to discretize the nonlocal operator, and apply the z-transform to the discrete nonlocal system in an exterior domain, and derive an exact solution expression for the discrete system. This solution expression is referred to our exact nonrefecting boundary condition and leads us to reformulate the original infnite discrete system into an equivalent fnite discrete system. Meanwhile, the trapezoidal quadrature rule is introduced to discretize the contour integral involved in exact boundary conditions. Numerical examples are fnally provided to demonstrate the efectiveness of our approach. 展开更多
关键词 Nonrefecting boundary conditions Artifcial boundary method Nonlocal Schrödinger equation Z-TRANSFORM Nonlocal models
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Study on the Mechanism of Angelica sinensis-Phellodendri Chinensis Cortex in the Treatment of Chronic Prostatitis Based on Network Pharmacology
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作者 Shengjing LIU Jun GUO +4 位作者 Fu WANG jiwei zhang Bin YAN Guanchao DU Qinghe GAO 《Medicinal Plant》 CAS 2021年第5期12-16,共5页
[Objectives]To explore the mechanism of Angelica sinensis-Phellodendri Chinensis Cortex in the treatment of chronic prostatitis(CP)based on the method of network pharmacology.[Methods]The active components and action ... [Objectives]To explore the mechanism of Angelica sinensis-Phellodendri Chinensis Cortex in the treatment of chronic prostatitis(CP)based on the method of network pharmacology.[Methods]The active components and action targets of Angelica sinensis-Phellodendri Chinensis Cortex were screened by(TCMSP),a systematic pharmacological analysis platform of traditional Chinese medicine,combined with literature search.The target was corrected by Uniprot database,and the disease CP target was screened by GeneCards and OMIM database.The common targets of drugs and diseases were screened by R language software,and the visual network map of drugs-active components-targets-diseases was constructed by Cytoscape 3.5.1 software.The common target protein-protein interaction(PPI)network was constructed by using STRING platform.The R language software was used to annotate and analyze the gene function and pathway of the core target through geneontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG).[Results]46 active components of Angelica sinensis-Phellodendri Chinensis Cortex were screened,and 212 related targets were predicted,of which 159 were related to disease.These targets were mainly involved in biological processes such as heterologous biological stimulation,oxidation and anti-oxidation,and were mainly concentrated in PI3K-Akt,mitogen-activated protein kinase(MAPK),hypoxia inducible factor-1(HIF-1)and other related signaling pathways.[Conclusions]The multi-component,multi-target and multi-pathway action characteristics of Angelica sinensis-Phellodendri Chinensis Cortex were confirmed by network pharmacology,and the possible mechanism of Angelica sinensis-Phellodendri Chinensis Cortex in the treatment of CP was predicted,which provided a theoretical basis for further experiments to verify its action mechanism. 展开更多
关键词 Angelica sinensis-Phellodendri Chinensis Cortex Chronic prostatitis Network pharmacology PI3K-Akt signaling pathway MAPK signaling pathway Guihuang prescription
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An Efficient Cartesian Grid-Based Method for Scattering Problems with Inhomogeneous Media
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作者 Haixia Dong Wenjun Ying jiwei zhang 《Numerical Mathematics(Theory,Methods and Applications)》 SCIE CSCD 2023年第2期541-564,共24页
Boundary integral equations provide a powerful tool for the solution of scattering problems.However,often a singular kernel arises,in which case the standard quadratures will give rise to unavoidable deteriorations in... Boundary integral equations provide a powerful tool for the solution of scattering problems.However,often a singular kernel arises,in which case the standard quadratures will give rise to unavoidable deteriorations in numerical precision,thus special treatment is needed to handle the singular behavior.Especially,for inhomogeneous media,it is difficult if not impossible to find out an analytical expression for Green’s function.In this paper,an efficient fourth-order accurate Cartesian grid-based method is proposed for the two-dimensional Helmholtz scattering and transmission problems with inhomogeneous media.This method provides an alternative approach to indirect integral evaluation by solving equivalent interface problems on Cartesian grid with a modified fourth-order accurate compact finite difference scheme and a fast Fourier transform preconditioned conjugate gradient(FFT-PCG)solver.A remarkable point of this method is that there is no need to know analytical expressions for Green’s function.Numerical experiments are provided to demonstrate the advantage of the current approach,including its simplicity in implementation,its high accuracy and efficiency. 展开更多
关键词 Transmission problem inhomogeneous media Cartesian grid-based method modified fourth-order compact difference scheme fast Fourier transform preconditioned conjugate gradient solver.
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SHARP POINTWISE-IN-TIME ERROR ESTIMATE OF L1 SCHEME FOR NONLINEAR SUBDIFFUSION EQUATIONS
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作者 Dongfang Li Hongyu Qin jiwei zhang 《Journal of Computational Mathematics》 SCIE 2024年第3期662-678,共17页
An essential feature of the subdiffusion equations with theα-order time fractional derivative is the weak singularity at the initial time.The weak regularity of the solution is usually characterized by a regularity p... An essential feature of the subdiffusion equations with theα-order time fractional derivative is the weak singularity at the initial time.The weak regularity of the solution is usually characterized by a regularity parameterσ∈(0,1)∪(1,2).Under this general regularity assumption,we present a rigorous analysis for the truncation errors and develop a new tool to obtain the stability results,i.e.,a refined discrete fractional-type Grönwall inequality(DFGI).After that,we obtain the pointwise-in-time error estimate of the widely used L1 scheme for nonlinear subdiffusion equations.The present results fill the gap on some interesting convergence results of L1 scheme onσ∈(0,α)∪(α,1)∪(1,2].Numerical experiments are provided to demonstrate the effectiveness of our theoretical analysis. 展开更多
关键词 Sharp pointwise-in-time error estimate Ll scheme Nonlinear subdiffusion equations Non-smooth solutions
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植物表皮毛研究进展 被引量:16
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作者 张继伟 赵杰才 +1 位作者 周琴 陈国雄 《植物学报》 CAS CSCD 北大核心 2018年第5期726-737,共12页
表皮毛是大多数植物地上部分表皮组织所延伸出来的一种特化的毛状结构附属物。表皮毛在植物表皮层和环境间构筑了一道天然的物理屏障,不但对植物的生长发育具有重要意义,而且还具有非常高的应用价值和经济价值。近几年,研究者从不同植... 表皮毛是大多数植物地上部分表皮组织所延伸出来的一种特化的毛状结构附属物。表皮毛在植物表皮层和环境间构筑了一道天然的物理屏障,不但对植物的生长发育具有重要意义,而且还具有非常高的应用价值和经济价值。近几年,研究者从不同植物中不断克隆出新的表皮毛发育相关基因,在揭示植物调控表皮毛生长发育的分子机制方面取得很大进展。该文综述了植物表皮毛的最新研究进展,并展望了植物表皮毛的研究方向及应用开发价值。 展开更多
关键词 表皮毛 物理屏障 发育 基因 分子机制
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MiR-139-5p inhibits migration and invasion of colorectal cancer by downregulating AMFR and NOTCH1 被引量:14
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作者 Mingxu Song Yuan Yin +12 位作者 jiwei zhang Binbin zhang Zehua Bian Chao Quan Leyuan Zhou Yaling Hu Qifeng Wang Shujuan Ni Bojian Fei Weili Wang Xiang Du Dong Hua Zhaohui Huang 《Protein & Cell》 SCIE CAS CSCD 2014年第11期851-861,共11页
MicroRNAs (miRNAs ) 由抑制最近在 carcinogenesis 和转移在我们 non-protein-coding RNA 的角色的理解带给卓见的 posttranscriptional 施加功能。在这研究,我们在 CRC 在 colorectal 癌症(CRC ) 和它的潜在的临床的应用程序描述了... MicroRNAs (miRNAs ) 由抑制最近在 carcinogenesis 和转移在我们 non-protein-coding RNA 的角色的理解带给卓见的 posttranscriptional 施加功能。在这研究,我们在 CRC 在 colorectal 癌症(CRC ) 和它的潜在的临床的应用程序描述了函数和 miR-139-5p 的分子的机制。我们发现 miR-139-5p 是显著地, CRC 与邻近的 noncancerous 纸巾(NCT ) 相比取样的在 73.8% 的 downregulated,和减少的 miR-139-5p 与穷人被联系预后。功能的分析证明 miR-139-5p 的那个宫外的表达式在 vivo 在 vitro 和转移压制了 CRC 房间移植和侵略。机械学的调查表明 miR-139-5p 由指向 AMFR 和 NOTCH1 压制 CRC 房间侵略和转移。二基因 phenocopied 击倒 CRC 上的 miR-139-5p 的禁止的效果转移。而且,二基因的蛋白质层次与 NCT 相比是在 CRC 样品的 upregulated,并且相反地与 miR-139-5p 表示相关。增加的 NOTCH1 蛋白质表示与 CRC 病人的差的预后被相关。一起,我们的数据显示 miR-139-5p 为 CRC 是潜在的肿瘤 suppressor 和预示的因素,并且指向 miR-139-5p 可以镇压 CRC 的转移并且改善幸存。 展开更多
关键词 结直肠癌 细胞迁移 侵袭 miRNA CRC 蛋白表达 蛋白质编码 微RNA
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MicroRNA-638 inhibits cell proliferation by targeting phospholipase D1 in human gastric carcinoma 被引量:8
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作者 jiwei zhang Zehua Bian +7 位作者 Jialiang Zhou Mingxu Song Zhihui Liu Yuyang Feng Li Zhe Binbin zhang Yuan Yin Zhaohui Huang 《Protein & Cell》 SCIE CAS CSCD 2015年第9期680-688,共9页
MicroRNAs (miRNAs ) 是经常是玩的小非编码的 RNA 的一种类型在 carcinogenesis 的重要角色,而是 miRNAs 的 carcinogenic 机制仍然是不清楚的。这研究将在癌(GC ) 调查功能和 miR-638 的机制。在 GC 和 miR-638 的 DNA 拷贝数字的 mi... MicroRNAs (miRNAs ) 是经常是玩的小非编码的 RNA 的一种类型在 carcinogenesis 的重要角色,而是 miRNAs 的 carcinogenic 机制仍然是不清楚的。这研究将在癌(GC ) 调查功能和 miR-638 的机制。在 GC 和 miR-638 的 DNA 拷贝数字的 miR-638 的表示被即时 PCR 检测。房间增长上的 miR-638 的效果被数 kit-8 试金测量。不同试金,包括生物信息学算法(TargetScan 并且人权保护) ,酶报告试金并且西方的弄污,被用来在 GC 识别 miR-638 的目标基因。在临床的 CRC 纸巾的 miR-638 目标基因的表示被 immunohistochemical 试金也验证。从这研究,我们发现 miR-638 与相应 noncancerous 纸巾(NCT ) 相比是在 GC 纸巾的 downregulated,并且 miR-638 的 DNA 拷贝数字比 NCT 在 GC 是更低的,它可以在 GC 导致 miR-638 的相应 downregulation。miR-638 的宫外的表示在 vitro 禁止了 GC 细胞生长。随后,我们鉴别 PLD1 是在 GC,和 silencing PLD1 表示 phenocopied 的 miR-638 的目标基因 GC 房间增长上的 miR-638 的禁止的效果。而且,我们观察到 PLD1 是在在预言的 GC 的 PLD1 的 GC 纸巾,和高表示的 overexpressed 差的全面幸存。在摘要,我们表明 miR-638 通过禁止 PLD1 在 GC 作为肿瘤 suppressor 工作。 展开更多
关键词 细胞增殖 胃癌 磷脂酶 miRNA MICRORNA PCR检测 CCK-8 生物信息学
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Correction to:MiR-139-5p inhibits migration and invasion of colorectal cancer by downregulating AMFR and NOTCH1 被引量:2
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作者 Mingxu Song Yuan Yin +12 位作者 jiwei zhang Binbin zhang Zehua Bian Chao Quan Leyuan Zhou Yaiing Hu Qifeng Wang Shujuan Ni Bojian Fei Weiii Wang Xiang Du Dong Hua Zhaohui Huang 《Protein & Cell》 SCIE CSCD 2021年第8期667-669,共3页
CORRECTION TO:PROTEIN CELL(2014)5(11):851-861 HTTPS://DOI.ORG/10.1007/S13238-014-0093-5 In the original publication the display of Fig.1 is in correct.The correct Fig.1 is available in this correction.
关键词 INVASION COLORECTAL cancer
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HIGH-ORDER LOCAL ABSORBING BOUNDARY CONDITIONS FOR HEAT EQUATION IN UNBOUNDED DOMAINS 被引量:1
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作者 Xiaonan Wu jiwei zhang 《Journal of Computational Mathematics》 SCIE CSCD 2011年第1期74-90,共17页
与数字方法的发展,数字计算要求越来越高的精确性。这份报纸被奉献给为热方程吸收边界条件(ABC ) 的高顺序的本地人。我们证明联合系统在计算领域产出在获得的高顺序的本地 ABC 和部分微分方程之间的一个稳定的问题。这个方法仅仅最近... 与数字方法的发展,数字计算要求越来越高的精确性。这份报纸被奉献给为热方程吸收边界条件(ABC ) 的高顺序的本地人。我们证明联合系统在计算领域产出在获得的高顺序的本地 ABC 和部分微分方程之间的一个稳定的问题。这个方法仅仅最近在波浪繁殖模型广泛地被使用了。我们扩大方法论的精神到寓言的,它将成为一个基础为非线性的 PDE 的一个班设计本地 ABC。一些数字测试证明新处理很有效、易控制。[从作者抽象] 展开更多
关键词 吸收边界条件 边界条件方程 无界区域 高阶 非线性偏微分方程 热量 基础知识 稳定性问题
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A review of common-path off-axis digital holography:towards high stable optical instrument manufacturing 被引量:4
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作者 jiwei zhang Siqing Dai +3 位作者 Chaojie Ma Teli Xi Jianglei Di Jianlin Zhao 《Light(Advanced Manufacturing)》 2021年第3期97-113,共17页
Digital holography possesses the advantages of wide-field,non-contact,precise,and dynamic measurements for the complex amplitude of object waves.Today,digital holography and its derivatives have been widely applied in... Digital holography possesses the advantages of wide-field,non-contact,precise,and dynamic measurements for the complex amplitude of object waves.Today,digital holography and its derivatives have been widely applied in interferometric measurements,three-dimensional imaging,and quantitative phase imaging,demonstrating significant potential in the material science,industry,and biomedical fields,among others.However,in conventional off-axis holographic experimental setups,the object and reference beams propagate in separated paths,resulting in low temporal stability and measurement sensitivity.By designing common-path configurations where the two interference beams share the same or similar paths,environmental disturbance to the two beams can be effectively compensated.Therefore,the temporal stability of the experimental setups for hologram recording can be significantly improved for time-lapsing measurements.In this review,we categorise the common-path models as lateral shearing,point diffraction,and other types based on the different approaches to generate the reference beam.Benefiting from compact features,common-path digital holography is extremely promising for the manufacture of highly stable optical measurement and imaging instruments in the future. 展开更多
关键词 SHEARING HOLOGRAPHIC PRECISE
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Numerical Investigations of a Class of Biological Models on Unbounded Domain 被引量:1
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作者 Qiumei Huang Dongfang Li jiwei zhang 《Numerical Mathematics(Theory,Methods and Applications)》 SCIE CSCD 2019年第1期169-186,共18页
This paper is concerned with numerical computations of a class of biologi-cal models on unbounded spatial domains.To overcome the unboundedness of spatial domain,we first construct efficient local absorbing boundary c... This paper is concerned with numerical computations of a class of biologi-cal models on unbounded spatial domains.To overcome the unboundedness of spatial domain,we first construct efficient local absorbing boundary conditions(LABCs)to re-formulate the Cauchy problem into an initial-boundary value(IBV)problem.After that,we construct a linearized finite difference scheme for the reduced IVB problem,and provide the corresponding error estimates and stability analysis.The delay-dependent dynamical properties on the Nicholson’s blowflies equation and the Mackey-Glass equa-tion are numerically investigated.Finally,numerical examples are given to demonstrate the efficiency of our LABCs and theoretical results of the numerical scheme. 展开更多
关键词 Biological models artificial boundary method absorbing boundary conditions finite difference method stability convergence
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STABILITY ANALYSIS FOR NONLINEAR SCHRODINGER EQUATIONS WITH NONLINEAR ABSORBING BOUNDARY CONDITIONS
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作者 jiwei zhang Zhenli Xu +1 位作者 Xiaonan Wu Desheng Wang 《Journal of Computational Mathematics》 SCIE CSCD 2017年第1期1-18,共18页
为非线性的 Schr 的本地吸收边界条件(LABC )? dinger
关键词 非线性薛定谔方程 吸收边界条件 稳定性分析 统一方法 能量估计 辅助变量 高阶导数 二维问题
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Numerical Solution of a One-Dimensional Nonlocal Helmholtz Equation by Perfectly Matched Layers
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作者 Yu Du jiwei zhang 《Numerical Mathematics(Theory,Methods and Applications)》 SCIE CSCD 2022年第2期387-414,共28页
We consider the computation of a nonlocal Helmholtz equation by using perfectly matched layer(PML).We first derive the nonlocal PML equation by extending PML modifications from the local operator to the nonlocal opera... We consider the computation of a nonlocal Helmholtz equation by using perfectly matched layer(PML).We first derive the nonlocal PML equation by extending PML modifications from the local operator to the nonlocal operator of integral form.After that,we give stability estimates of some weighted-average values of the nonlocal Helmholtz solution and prove that(i)the weighted-average value of the nonlocal PML solution decays exponentially in PML layers in one case;(ii)in the other case,the weighted-average value of the nonlocal Helmholtz solution itself decays exponentially outside some domain.Particularly for a typical kernel functionγ_(1)(s)=1/2 e^(−|s|),we obtain the Green’s function of the nonlocal Helmholtz equation,and use the Green’s function to further prove that(i)the nonlocal PML solution decays exponentially in PML layers in one case;(ii)in the other case,the nonlocal Helmholtz solution itself decays exponentially outside some domain.Based on our theoretical analysis,the truncated nonlocal problems are discussed and an asymptotic compatibility scheme is also introduced to solve the resulting truncated problems.Finally,numerical examples are provided to verify the effectiveness and validation of our nonlocal PML strategy and theoretical findings. 展开更多
关键词 Nonlocal wave propagation Helmholtz equation perfectly matched layer asymptotic compatibility scheme Green’s function
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带初始奇异性的多项时间分数阶扩散方程一类全离散数值方法的误差分析
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作者 任金城 陈虎 +1 位作者 张继伟 张智民 《中国科学:数学》 CSCD 北大核心 2021年第8期1279-1296,共18页
本文研究了带有初始奇异性的多项时间分数阶扩散方程的一种全离散数值方法.首先,基于L1公式在渐变网格下离散多项Caputo时间分数阶导数,构造了多项时间分数阶扩散方程的时间半离散格式,证明了时间格式通过选取合适的网格参数r,时间方向... 本文研究了带有初始奇异性的多项时间分数阶扩散方程的一种全离散数值方法.首先,基于L1公式在渐变网格下离散多项Caputo时间分数阶导数,构造了多项时间分数阶扩散方程的时间半离散格式,证明了时间格式通过选取合适的网格参数r,时间方向的误差可以达到最优的收敛阶2-α1,其中α1(0 <α1<1)为多项时间分数阶导数阶数的最大值.然后,空间采用谱方法进行离散,得到了全离散格式,证明了全离散格式的无条件稳定性和收敛性.为了降低计算量和储存量,对多项时间分数阶扩散方程又构造了时间方向的快速算法,同时证明了该格式的收敛性.数值算例验证了算法的有效性,显示了快速算法的高效性. 展开更多
关键词 多项时间分数阶扩散方程 弱奇异性 L1格式 渐变网格 收敛性
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Efficient Numerical Computation of Time-Fractional Nonlinear Schrodinger Equations in Unbounded Domain
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作者 jiwei zhang Dongfang Li Xavier Antoine 《Communications in Computational Physics》 SCIE 2019年第1期218-243,共26页
The aim of this paper is to derive a stable and efficient scheme for solving the one-dimensional time-fractional nonlinear Schrodinger equation set in an unbounded domain.We first derive absorbing boundary conditions ... The aim of this paper is to derive a stable and efficient scheme for solving the one-dimensional time-fractional nonlinear Schrodinger equation set in an unbounded domain.We first derive absorbing boundary conditions for the fractional system by using the unified approach introduced in[47,48]and a linearization procedure.Then,the initial boundary-value problem for the fractional system with ABCs is discretized,a stability analysis is developed and the error estimate O(h^(2)+τ)is stated.To accel-erate the L1-scheme in time,a sum-of-exponentials approximation is introduced to speed-up the evaluation of the Caputo fractional derivative.The resulting algorithm is highly efficient for long time simulations.Finally,we end the paper by reporting some numerical simulations to validate the properties(accuracy and efficiency)of the derived scheme. 展开更多
关键词 Time-fractional nonlinear Schrodinger equation absorbing boundary condition sta-bility analysis convergence analysis sum-of-exponentials approximation
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Analysis of L1-Galerkin FEMs for Time-Fractional Nonlinear Parabolic Problems
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作者 Dongfang Li Hong-Lin Liao +2 位作者 Weiwei Sun Jilu Wang jiwei zhang 《Communications in Computational Physics》 SCIE 2018年第6期86-103,共18页
This paper is concerned with numerical solutions of time-fractional nonlinear parabolic problems by a class of L1-Galerkin finite element methods.The analysis of L1 methods for time-fractional nonlinear problems is li... This paper is concerned with numerical solutions of time-fractional nonlinear parabolic problems by a class of L1-Galerkin finite element methods.The analysis of L1 methods for time-fractional nonlinear problems is limited mainly due to the lack of a fundamental Gronwall type inequality.In this paper,we establish such a fundamental inequality for the L1 approximation to the Caputo fractional derivative.In terms of the Gronwall type inequality,we provide optimal error estimates of several fully discrete linearized Galerkin finite element methods for nonlinear problems.The theoretical results are illustrated by applying our proposed methods to the time fractional nonlinear Huxley equation and time fractional Fisher equation. 展开更多
关键词 Time-fractional nonlinear parabolic problems L1-Galerkin FEMs Error estimates discrete fractional Gronwall type inequality Linearized schemes
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Artificial Boundary Conditions for Nonlocal Heat Equations on Unbounded Domain
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作者 Wei zhang Jiang Yang +1 位作者 jiwei zhang Qiang Du 《Communications in Computational Physics》 SCIE 2017年第1期16-39,共24页
This paper is concerned with numerical approximations of a nonlocal heat equation define on an infinite domain.Two classes of artificial boundary conditions(ABCs)are designed,namely,nonlocal analog Dirichlet-to-Neuman... This paper is concerned with numerical approximations of a nonlocal heat equation define on an infinite domain.Two classes of artificial boundary conditions(ABCs)are designed,namely,nonlocal analog Dirichlet-to-Neumann-type ABCs(global in time)and high-order Pad´e approximate ABCs(local in time).These ABCs reformulate the original problem into an initial-boundary-value(IBV)problem on a bounded domain.For the global ABCs,we adopt a fast evolution to enhance computational efficiency and reduce memory storage.High order fully discrete schemes,both second-order in time and space,are given to discretize two reduced problems.Extensive numerical experiments are carried out to show the accuracy and efficiency of the proposed methods. 展开更多
关键词 Artificial boundary conditions nonlocal models Pad´e approximation nonlocal heat equations artificial boundary method
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