Journal of Mathematical Chemistry最新文献_第9页

A time two-grid difference method for nonlinear generalized viscous Burgers’ equation 非线性广义粘性布尔格斯方程的时间双网格差分法

IF 1.7 3区化学

Journal of Mathematical Chemistry Pub Date : 2024-03-28 DOI: 10.1007/s10910-024-01592-x

Yang Shi, Xuehua Yang

{"title":"A time two-grid difference method for nonlinear generalized viscous Burgers’ equation","authors":"Yang Shi, Xuehua Yang","doi":"10.1007/s10910-024-01592-x","DOIUrl":"10.1007/s10910-024-01592-x","url":null,"abstract":"<div><p>In this paper, we investigate a time two-grid algorithm to get the numerical solution of nonlinear generalized viscous Burgers’ equation, which is the first time that the two-grid method is used to solve this problem. Based on Crank–Nicolson finite difference scheme, we establish the time two-grid difference (TTGD) scheme which consists of three computational procedures to reduce the computational cost compared with the general finite difference (GFD) scheme. The cut-offf function method is applied to prove the conservation, unique solvability, the prior estimate and convergence in <span>(L^2)</span>-norm and <span>(L^{infty })</span>-norm of the TTGD scheme on the coarse grid and fine grid, respectively. Comparing our TTGD scheme with GFD scheme in Zhang et al. (Appl Math Lett 112:106719, 2021), we provided the proof the uniqueness the solution of the nonlinear scheme, direct proof of convergence in <span>(L^2)</span>-norm and the prior estimate both on the coarse mesh and fine mesh. The numerical results show that our TTGD scheme is more efficient than the GDF scheme in Zhang et al. (2021) in terms of the CPU time. Particularly, our method not only improves the efficiency, but also preserves the energy conservation of the original model.</p></div>","PeriodicalId":648,"journal":{"name":"Journal of Mathematical Chemistry","volume":"62 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140312641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Pivotal condensation and chemical balancing 枢轴凝结和化学平衡

IF 1.7 3区化学

Journal of Mathematical Chemistry Pub Date : 2024-03-27 DOI: 10.1007/s10910-024-01594-9

Hans-Christian Herbig

{"title":"Pivotal condensation and chemical balancing","authors":"Hans-Christian Herbig","doi":"10.1007/s10910-024-01594-9","DOIUrl":"10.1007/s10910-024-01594-9","url":null,"abstract":"<div><p>A universal method, called <i>pivotal condensation</i>, for calculating stoichiometric factors of chemical reactions is presented. It is based on our new approach for calculating the basis of the kernel of a matrix over the field of rational numbers. This approach is referred to as <i>kernel pivotal condensation</i> (ker pc) and is presented in detail. It has roughly the same complexity as Gaussian elimination, but can be performed without working with fractions. It is also shown how ker pc can be adapted as a tool to solve inhomogeneous linear systems, invert matrices (this is referred to as <i>inv pc</i>) and determine simultaneously the four subspaces (referred to as <i>4 pc</i>). Besides, the balancing by inspection method, which is widely used in practice to reduce the size of a linear system arising in chemical balancing, is formulated in a mathematical language. When calculating stoichiometric factors of chemical balancing problems with a non-unique solution the natural question arises how to determine a basis that generates all the solutions over the integers. A method, referred to as <i>smitheration</i>, is introduced that permits to determine such an integer basis from a basis over the rational numbers. If there are few solutions this approach is more efficient than calculating a Smith normal form directly. It is convenient to work over principal ideal domains instead of the ring of integers, so that one can treat balancing problems that depend on one parameter as well.</p></div>","PeriodicalId":648,"journal":{"name":"Journal of Mathematical Chemistry","volume":"62 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140312655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A high-order B-spline collocation method for solving a class of nonlinear singular boundary value problems 求解一类非线性奇异边界值问题的高阶 B-样条配位法

IF 1.7 3区化学

Journal of Mathematical Chemistry Pub Date : 2024-03-26 DOI: 10.1007/s10910-024-01590-z

Pradip Roul

引用次数: 0

Correction: The dual descriptor potential 更正：双重描述势

IF 1.7 3区化学

Journal of Mathematical Chemistry Pub Date : 2024-03-26 DOI: 10.1007/s10910-024-01616-6

Jorge Martínez-Araya

引用次数: 0

Unsteady triple diffusive oscillatory flow in a Voigt fluid 沃伊特流体中的非稳态三重扩散振荡流

IF 1.7 3区化学

Journal of Mathematical Chemistry Pub Date : 2024-03-24 DOI: 10.1007/s10910-024-01591-y

Y. Vinod, Suma Nagendrappa Nagappanavar, Sangamesh, K. R. Raghunatha, D. L. Kiran Kumar

{"title":"Unsteady triple diffusive oscillatory flow in a Voigt fluid","authors":"Y. Vinod, Suma Nagendrappa Nagappanavar,  Sangamesh, K. R. Raghunatha, D. L. Kiran Kumar","doi":"10.1007/s10910-024-01591-y","DOIUrl":"10.1007/s10910-024-01591-y","url":null,"abstract":"<div><p>Convective energy and mass transfer in a non-Newtonian fluid layers a wide-spread physical phenomenon in natural and technical systems. Triple diffusive convection plays a crucial role in chemical engineering by enabling the understanding and optimisation of mass transfer processes involving multiple components. It is essential for designing efficient separation systems, optimising catalysts, predicting reaction kinetics, and improving environmental processes. The motivation of this paper is to explore an Oscillatory flow of a triple diffusive convection in a Voigt fluid layer. The governing partial differential equations are transformed into coupled ordinary differential equations with the help of the oscillation technique. The study emphasises the effects of known physical parameters, such as the thermal Grashof number, solutal Grashof number, Prandtl number, Lewis numbers and Voigt fluid parameters on velocity, temperature, concentrations and rate of heat and mass transfers. In particularly, the study finds that skin friction increases on both channel plates with increasing injection on the heated plate.</p></div>","PeriodicalId":648,"journal":{"name":"Journal of Mathematical Chemistry","volume":"62 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140302183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

In vivo brain MRS at a 1.5T clinical scanner: Optimized derivative fast Fourier transform for high-resolution spectra from time signals encoded with and without water suppression 在 1.5T 临床扫描仪上进行活体脑 MRS 扫描：优化衍生快速傅立叶变换，从有水抑制和无水抑制的时间信号编码中获得高分辨率光谱

IF 1.7 3区化学

Journal of Mathematical Chemistry Pub Date : 2024-03-22 DOI: 10.1007/s10910-024-01597-6

Dževad Belkić, Karen Belkić

{"title":"In vivo brain MRS at a 1.5T clinical scanner: Optimized derivative fast Fourier transform for high-resolution spectra from time signals encoded with and without water suppression","authors":"Dževad Belkić, Karen Belkić","doi":"10.1007/s10910-024-01597-6","DOIUrl":"10.1007/s10910-024-01597-6","url":null,"abstract":"<div><p>We study single-voxel in vivo proton magnetic resonance spectroscopy (MRS) of white matter in the brain of a 25 year old healthy male volunteer. The free induction decay (FID) data of short length (0.5KB) are encoded at a long echo time (272 ms) with and without water suppression at a clinical scanner of a weak magnetic field (1.5T). For these FIDs, the fast Fourier transform (FFT) gives sparse, rough and metabolically uninformative spectra. In such spectra, resolution and signal to noise ratio (SNR) are poor. Exponential or Gaussian filters applied to the FIDs can improve SNR in the FFT spectra, but only at the expense of the worsened resolution. This impacts adversely on in vivo MRS for which both resolution and SNR of spectra need to be very good or excellent, without necessarily resorting to stronger magnetic fields. Such a long sought goal is at last within reach by means of the optimized derivative fast Fourier transform (dFFT), which dramatically outperforms the FFT in every facet of signal estimations. The optimized dFFT simultaneously improves resolution and SNR in derivative spectra. They are presently shown to be of comparably high quality irrespective of whether water is suppressed or not in the course of FID encodings. The ensuing benefits of utmost relevance in the clinic include a substantial shortening of the patient examination time. The implied significantly better cost-effectiveness should make in vivo MRS at low-field clinical scanners (1.5T) more affordable to ever larger circles of hospitals worldwide.</p></div>","PeriodicalId":648,"journal":{"name":"Journal of Mathematical Chemistry","volume":"62 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10910-024-01597-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140198839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

On the thermal properties of pure and defective Ψ-graphene nanotubes by molecular dynamics simulations 通过分子动力学模拟研究纯Ψ-石墨烯纳米管和缺陷Ψ-石墨烯纳米管的热特性

IF 1.7 3区化学

Journal of Mathematical Chemistry Pub Date : 2024-03-21 DOI: 10.1007/s10910-024-01588-7

Pingfang Yuan, Zhenfeng Liu, Yanxin Xie, Yafei Meng, Mengdie Li, Keke Chen

引用次数: 0

Numerical approach for time-fractional Burgers’ equation via a combination of Adams–Moulton and linearized technique 结合亚当斯-莫尔顿和线性化技术的时间分数布尔格斯方程数值方法

IF 1.7 3区化学

Journal of Mathematical Chemistry Pub Date : 2024-03-18 DOI: 10.1007/s10910-024-01589-6

Yonghyeon Jeon, Sunyoung Bu

引用次数: 0

Improved rotating Kratzer–Fues oscillator: eigenenergies, eigenfunctions, coherent states and ladder operators 改进的旋转克拉策-福斯振荡器：特征能、特征函数、相干态和梯形算子

IF 1.7 3区化学

Journal of Mathematical Chemistry Pub Date : 2024-03-16 DOI: 10.1007/s10910-024-01585-w

Marcin Molski

引用次数: 0

Correction: Why are the local hyper-softness and the local softness more appropriate local reactivity descriptors than the dual descriptor and the Fukui function, respectively? 更正：为什么局部超软度和局部软度分别比对偶描述符和福井函数更适合作为局部反应性描述符？

IF 1.7 3区化学

Journal of Mathematical Chemistry Pub Date : 2024-03-15 DOI: 10.1007/s10910-024-01613-9

Jorge I. Martínez-Araya

引用次数: 0