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Efficient finite difference method for two-dimensional diffusion equation in comb structure with fractional derivative boundary conditions 认领 引用
1
作者 Weiping Bu Xiaohong Xu Yue Zhao 《International Journal of Modeling, Simulation, and Scientific Computing》 EI 2025年第1期120-147,共28页
In[Liu L.,Chen S.,Feng L.,Wang J.,Zhang S.,Chen Y.,Si X.,Zheng L.,Analysis of the anomalous diffusion in comb structure with absorbing boundary conditions,J.Comput.Phys.490:112315,2023],an anomalous diffusion model in... In[Liu L.,Chen S.,Feng L.,Wang J.,Zhang S.,Chen Y.,Si X.,Zheng L.,Analysis of the anomalous diffusion in comb structure with absorbing boundary conditions,J.Comput.Phys.490:112315,2023],an anomalous diffusion model in comb structure is simulated by finite difference method,which exhibits a low convergence rate in time compared to space.It inspires us to enhance temporal convergence accuracy for this interesting problem.In this paper,we first consider the finite difference method of normal diffusion equation in comb structure which can be viewed as a natural generalization of the anomalous diffusion case.Then we use finite difference method to solve the above anomalous diffusion problem.Unlike the existed work which employs L1 method to discrete the fractional derivative of the considered equation,the Crank-Nicolson method is used for integer-order problem and L2-1σmethod is used for fractional problem here.For these two proposed numerical schemes,their stability and convergence are discussed,respectively.For the fractional problem,the present convergence result shows that the accuracy in time has been obviously improved compared with the existed work.Finally,the obtained theoretical results are verified by some numerical tests. 展开更多
关键词 Diffusion in comb structure fractional derivative boundary condition finite difference method L2-1σmethod stability and convergence
Coal-gas interaction: implications of changes in texture and porosity 认领 引用 被引量：13
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作者 Vyacheslav N. Romanov Lauren C. Graeser +2 位作者 Sinisha A. Jikich Yee Soong Gino A. Irdi 《International Journal of Coal Science & Technology》 EI CAS 2016年第1期10-19,共10页
Transient sorption and desorption of helium and carbon dioxide in Upper Freeport coal powder and lumps were analyzed. Differences in texture and porosity between the powder and lumps may affect the transport and inter... Transient sorption and desorption of helium and carbon dioxide in Upper Freeport coal powder and lumps were analyzed. Differences in texture and porosity between the powder and lumps may affect the transport and interaction of the penetrant and coal. In this work, we address macroscopic and mesoscopic structural differences between powdered and non-powdered coals that influence the rates of the gas transport kinetics and changes in coal texture （swelling, shrinkage, and changes in the pore structure and interconnectivity） and the reciprocal free-phase pressure decay （relaxation）. Com- parison of the multi-exponential relaxation time constants as a function of pressure, for CO2 and inert gas （helium）, allows us to postulate several mechanisms responsible for observed pressure decay patterns. 展开更多
关键词 Coal Gas Porosity Structure Diffusion Sorption Swelling
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Diffusion and sound absorption properties of the quadratic residue diffuser structure with perforated panel 认领 引用 被引量：3
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作者 CAI Jun BAO Fei +1 位作者 WANG Yachen WANG Yanqin 《Chinese Journal of Acoustics》 CSCD 2016年第3期255-264,共10页
Acoustic structure study always is the academic research interest. Diffusion ab？sorbing structure（DiflFsorber） has good research value because it has both diflFusion property and sound absorption property. Quadrati... Acoustic structure study always is the academic research interest. Diffusion ab？sorbing structure（DiflFsorber） has good research value because it has both diflFusion property and sound absorption property. Quadratic residue diffusers（QRD） structure which had good diffusion property was combined with the perforated panel which had good sound absorption property in this study. According to standard AES-4id-2001, the diffusion experiments were carried out to study QRD structure and ones composited with perforated-panels which had1 mm-thickness and perforated percentage of 3%, 5%, 8% respectively. The polar coordinate diagrams of different structure were analyzed to derive the diffusion coefficients. Results showed that the composite structure still had good diffusion performance in the frequency range from100 Hz to 800 Hz. The reflection sound energy of composite structure reduced obviously in the perforated panel resonance frequency range where there was about 2 dB reduction averagely.The study result can provide the reference for the design and development of diifsorber. 展开更多
关键词 rate Diffusion and sound absorption properties of the quadratic residue diffuser structure with perforated panel
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Candidate Biomarkers in Children with Autism Spectrum Disorder: A Review of MRI Studies 认领 引用 被引量：9
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作者 Dongyun Li Hans-Otto Karnath Xiu Xu 《Neuroscience Bulletin》 SCIE CAS CSCD 2017年第2期219-237,共19页
Searching for effective biomarkers is one of the most challenging tasks in the research ？eld of Autism Spectrum Disorder（ASD）. Magnetic resonance imaging（MRI） provides a non-invasive and powerful tool for investi... Searching for effective biomarkers is one of the most challenging tasks in the research ？eld of Autism Spectrum Disorder（ASD）. Magnetic resonance imaging（MRI） provides a non-invasive and powerful tool for investigating changes in the structure, function, maturation,connectivity, and metabolism of the brain of children with ASD. Here, we review the more recent MRI studies in young children with ASD, aiming to provide candidate biomarkers for the diagnosis of childhood ASD. The review covers structural imaging methods, diffusion tensor imaging, resting-state functional MRI, and magnetic resonance spectroscopy. Future advances in neuroimaging techniques, as well as cross-disciplinary studies and largescale collaborations will be needed for an integrated approach linking neuroimaging, genetics, and phenotypic data to allow the discovery of new, effective biomarkers. 展开更多
关键词 Autism spectrum disorder Biomarker Neuroimaging Structural MRI Diffusion tensor imaging Resting-state functional MRI Magnetic resonance spectroscopy Children Human
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Can multi-modal neuroimaging evidence from hippocampus provide biomarkers for the progression of amnestic mild cognitive impairment? 认领 引用 被引量：5
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作者 Jiu Chen Zhijun Zhang Shijiang Li 《Neuroscience Bulletin》 SCIE CAS CSCD 2015年第1期128-140,共13页
Impaired structure and function of the hippocampus is a valuable predictor of progression from amnestic mild cognitive impairment（a MCI） to Alzheimer＇s disease（AD）. As a part of the medial temporal lobe memory sy... Impaired structure and function of the hippocampus is a valuable predictor of progression from amnestic mild cognitive impairment（a MCI） to Alzheimer＇s disease（AD）. As a part of the medial temporal lobe memory system,the hippocampus is one of the brain regions affected earliest by AD neuropathology,and shows progressive degeneration as a MCI progresses to AD. Currently,no validated biomarkers can precisely predict the conversion from a MCI to AD. Therefore,there is a great need of sensitive tools for the early detection of AD progression. In this review,we summarize the specifi c structural and functional changes in the hippocampus from recent a MCI studies using neurophysiological and neuroimaging data. We suggest that a combination of advanced multi-modal neuroimaging measures in discovering biomarkers will provide more precise and sensitive measures of hippocampal changes than using only one of them. These will potentially affect early diagnosis and disease-modifying treatments. We propose a new sequential and progressive framework in which the impairment spreads from the integrity of fibers to volume and then to function in hippocampal subregions. Meanwhile,this is likely to be accompanied by progressive impairment of behavioral and neuropsychological performance in the progression of a MCI to AD. 展开更多
关键词 Alzheimer＇s disease amnestic mild cognitive impairment hippocampus episodic memory functional magnetic resonance imaging structural magnetic resonance imaging diffusion tensor imaging multi-modal MRI biomarker
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