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Constructing exactly conservative scheme in a non-conservative form

COMPUTER PHYSICS COMMUNICATIONS 2000年第3期126卷 232-243页

作者： Tanaka, R Nakamura, T Yabe, T Tokyo Inst Technol Dept Energy Sci Midori Ku Yokohama Kanagawa 2268502 Japan

A non-conservative scheme that guarantees exact mass conservation is proposed, Although it is in a non-conservative form, the mass of each cell is employed as an additional variable that is advanced in a conservative form. Some numerical tests are carried out to demonstrate the mass conservation and the accurate calculation of the speed of a shock wave even without the viscosity term. (C) 2000 Elsevier Science B.V. All rights reserved.

关键词： CIP computational algorithm mass conservation semi-Lagrangian

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Dynamic analysis of the suspended composite pipelines conveying pulsating fluid

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JOURNAL OF NATURAL GAS SCIENCE AND ENGINEERING 2020年 75卷 103148-000页

作者： Khudayarov, B. A. Komilova, Kh M. Turaev, F. Zh Tashkent Inst Irrigat & Agr Mechanizat Engineers Dept Higher Math Tashkent 100000 Uzbekistan Dept Higher Math Str Kari Niyazova 39 Tashkent 100000 Uzbekistan

The problems of oscillations of a viscoelastic pipeline conveying fluid flow are considered in the paper. Mathematical models of these problems are constructed in a one-dimensional statement. The motion of a pipeline completely filled with a flowing fluid is studied. The transverse oscillations of a pipeline interact with the pipe walls, changing the nature of system oscillations. It is assumed that a pulsating fluid flows in the pipeline. Though the effect of flowing fluid on the pipe motion is considered in the paper, the effect of the pipe on fluid flow is not taken into account here. The mathematical model of the problem is described by the systems of partial integro-differential equations (IDE) with corresponding initial and boundary conditions. Partial IDE obtained using the Bubnov-Galerkin method under considered boundary conditions are reduced to solving ordinary IDE systems with constant coefficients relative to time function. The integration of systems of equations obtained on the basis of a polynomial approximation of deflections was carried out numerically. Based on this method, the algorithms are developed for numerically solving one-dimensional problems of oscillation and stability of viscoelastic pipes conveying fluid flow. It was found that an increase in internal pressure parameter leads to a decrease in critical flow rate. It was shown that an increase in the singularity parameter and the rigidity parameter of continuous layer of a base leads to an increase in critical flow rate. It was revealed that an increase in transverse stationary external load leads to an increase in the amplitude of pipe oscillations.

关键词： Numerical simulation computational algorithm Viscoelasticity Pipeline Vibration Pulsating fluid

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TECHNOLOGY OF REGENERATION OF THE BONE TISSUE IN A ROTATIONAL BIOREACTOR: FLUID FLOW SIMULATION AND LASER-INDUCED FLUORESCENCE DIAGNOSTICS

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JOURNAL OF APPLIED MECHANICS AND TECHNICAL PHYSICS 2020年第5期61卷 776-786页

作者： Tsibulskaya, E. O. Maslov, N. A. Larionov, P. M. Ganimedov, V. L. Russian Acad Sci Khristianovich Inst Theoret & Appl Mech Siberian Branch Novosibirsk 630090 Russia Novosibirsk State Univ Novosibirsk 630090 Russia

A technology of bone tissue cultivation on a thin scaffold in a rotational bioreactor is developed. An optimal regime of cell material cultivation is determined for testing the method, and an optical method for diagnostics of the bone growth dynamics during its cultivation is found. Numerical simulations of the fluid flow in the bioreactor make it possible to significantly simplify the medical experiment and to choose the optimal values of the rotation frequencies and shear stresses acting on the cell material placed on the scaffold. The optical diagnostics of the scaffold samples in the course of dynamic cultivation in the bioreactor is performed by the method of laser-induced fluorescence. An algorithm based on the principal component analysis is applied to analyze the spectral data;as a result, the spectra of excitation and fluorescent emission of the basic fluorescent substances in the sample (tyrosine and tryptophan amino acids, structural protein (collagen), and fluorescent structures of polycaprolactone) are calculated. It is found that the contribution of the component corresponding to collagen in the samples increases in the process of dynamic cultivation, which testifies to effective formation of the extracellular matrix of the bone.

关键词： mathematical modeling computational algorithm rotational bioreactor Taylor vortices Navier– Stokes equations laminar flow regime shear stress scaffold laser-induced fluorescence principal component analysis

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Restoration of Boundary Mode for Two-phase Flow in Oil Pool

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JOURNAL OF AUTOMATION AND INFORMATION SCIENCES 2012年第8期44卷 22-31页

作者： Gamzayev, Kh. M. Azerbaijan State Oil Acad Baku Azerbaijan

The inverse problem related to restoration of boundary conditions in the boundary statement for the equations of two-phase flow in oil pool is considered. The difference analog of the problem is constructed using the method "implicit by the pressure - explicit by the saturation" and computational algorithm of solving the obtained system of difference equations is presented.

关键词： two-phase flow oil pool system of difference equations computational algorithm difference equations

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Three-dimensional numerical modeling of the temporal evolution of backward erosion piping

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COMPUTERS AND GEOTECHNICS 2024年 171卷

作者： Wang, Zhijie Oskay, Caglar Fascetti, Alessandro Univ Pittsburgh Dept Civil & Environm Engn 3700 OHara St Pittsburgh PA 15261 USA Vanderbilt Univ Dept Civil & Environm Engn 2301 Vanderbilt Pl Nashville TN 37235 USA

Backward erosion piping (BEP) is a complex degradation mechanism in geotechnical flood protection infrastructure (GFPI) that is still relatively less understood, particularly when considering its time -dependent features. This manuscript presents a novel dual random lattice modeling approach for three-dimensional simulation of BEP, with a focus on its evolution over time. The key novelty of this presented framework is twofold: (1) we propose and incorporate a novel constitutive relationship for computation of time -dependent soil erosion based on the theory of rate processes, and (2) we devise an algorithm for calculation of coupled degradation of the dual lattices for accurate computation of 3-D hydraulic gradients. The constitutive relationship was developed from fundamental granular physics, and brings the potential to provide deeper fundamental physical understanding of the phenomenon. The capabilities of the modeling framework are investigated by comparison with available laboratory experiments which illustrates good agreement in the spatial advancement of piping erosion, pipe progression speeds, as well as the evolution of local gradients. To the best knowledge of the authors, the presented model is the first to be able to capture all of the aforementioned features when simulating BEP.

关键词： Backward erosion piping Numerical modeling Constitutive law Time evolution computational algorithm

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An exponential queue with competition for service

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EUROPEAN JOURNAL OF OPERATIONAL RESEARCH 2000年第3期126卷 587-602页

作者： Brill, PH Hlynka, M Univ Windsor Dept Math & Stat Windsor ON N9B 3P4 Canada Univ Windsor Dept Management Sci Windsor ON N9B 3P4 Canada

We consider an M/M/c queue, where a single 'special' customer C-p arrives. If C-p must wait, then either C-p will eventually start service at some completion epoch with probability p, or C-p will 'float' into service at the end of a busy period. The model is interpreted as C-p competing for service against the regular customers. We study the waiting time of C-p. We analyze the effect of C-p on the waiting times of the regular customers. Examples and applications are discussed. (C) 2000 Elsevier Science B.V. All rights reserved.

关键词： queueing M/M/c ballot theorem Laplace-Stieltjes transform computational algorithm

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Observations of convergence and uniqueness of node-based bone remodeling simulations

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ANNALS OF BIOMEDICAL ENGINEERING 1997年第2期25卷 261-268页

作者： Fischer, KJ Jacobs, CR Levenston, ME Carter, DR DEPT VET AFFAIRS MED CTR REHABIL RES & DEV CTRPALO ALTOCA STANFORD UNIV DEPT ENGN MECHBIOMECH ENGN PROGRAMSTANFORDCA 94305

Some investigators have indicated that mathematical theories and computational models of bone adaptation may not converge and that the density solutions from such simulations are dependent on the initial density distribution. In this study, two-dimensional finite element models were used to investigate the effect of initial density distribution on the final density distribution produced using a node-based bone remodeling simulation. The first model was a generic long bone, and the second was a proximal femur. For each model, we conducted time-dependent, node-based, linear rate-law bone remodeling simulations. Five initial density conditions were used with the generic long bone and three with the proximal femur, Remodeling simulations were performed, and the largest average nodal density differences at the end of the simulations were 0.000010 g/cm(3) and 0.000006 g/cm(3) for the generic long bone and proximal femur models, respectively. Results illustrate that, for a given set of loads and a given finite element model, the node-based bone adaptation algorithm can yield a unique density distribution, In conjunction with previous studies, this finding suggests that uniqueness of the density solution is dependent on both the mathematical theory and the computational implementation.

关键词： initial conditions density distribution finite element model bone load estimation computational algorithm

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Estimating pro-environmental potential for the development of mobility-based informational intervention: a data-driven algorithm

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PERSONAL AND UBIQUITOUS COMPUTING 2019年第5-6期23卷 653-668页

作者： Ahmed, Shiraz Adnan, Muhammad Janssens, Davy Brattich, Erika Yasar, Ansar-ul-Haque Kumar, Prashant di Sabatino, Silvana Shakshuki, Elhadi M. UHasselt Hasselt Univ Transportat Res Inst IMOB Agoralaan B-3590 Diepenbeek Belgium Univ Bologna Alma Mater Studiorum Dept Phys & Astron Bologna Italy Univ Surrey Fac Engn & Phys Sci Global Ctr Clean Air Res GCARE Dept Civil & Environm Engn Guildford GU2 7XH Surrey England Acadia Univ Jodrey Sch Comp Sci Wolfville NS Canada

Informational interventions are important to bring positive changes in attitudes and perception among individuals. In relation to the individual's mobility behavior, habits, attitudes, and perceptions are difficult to change. Therefore, it is vital to identify relatively soft aspects of travel behavior with a potential to reduce the negative impacts of mobility on the environment and individual health. This paper provides a methodological framework and describes the development of a computational algorithm that helps to identify soft changes in the travel behavior. The algorithm is based on a variety of different data sources such as activity-travel diaries and related constraint information, meteorological conditions, bicycle and public transport supply data, and emissions and air pollutant concentrations data. A variety of rules that are part of the algorithm are derived from the transport modeling literature, where constraints and factors were examined for activity-travel decisions. Three major aspects of activity-travel behavior, such as reduced car use, cold start of car engines, and participation in non-mandatory outdoor activities are considered in assessing pro-environmental potential. The algorithm is applied to collected small datasets from citizens of Hasselt (Belgium), Bologna (Italy), and Guildford (UK). A significant replaceable potential for car trips within 3 km to cycling and car trips to public transport has been found. The replaceable potential of excessive cold starts and participation in non-mandatory outdoor activities were also found, to some extent, to bring positive changes in the environment. In future research, these identified potentials are reported back to individuals with their consequence as part of a mobility-based informational intervention.

关键词： Pro-environmental potential Activity-travel behavior Informational intervention computational algorithm

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Exact solution of bending problem for continuous sandwich panels with profiled facings

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JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 2014年 101卷 53-60页

作者： Gosowski, Bronislaw Gosowski, Maciej Wroclaw Univ Technol Inst Bldg Engn PL-50370 Wroclaw Poland PROKON PL-54142 Wroclaw Poland

The paper presents a closed-form solution, in the distributional form, of the bending problem for continuous sandwich panels in lightweight cladding that has been derived from the general solution of the system of differential equations for the problem of sandwich beams with thick facings. The analysis covers three-layer members with facings made from profiled metal sheets and a core having good insulating properties, for any number and spacing of elastic intermediate supports. Panels are subjected to bending under uniform transverse load and a load caused by temperature difference. The solution for the multi-span panels inflexibly (rigidly) pin-supported at their ends is derived from the general solution for members arbitrarily supported at their ends. A calculation algorithm for this type of panels is provided. Numerical examples are included to illustrate the influence of the intermediate supports on the effort of both the entire sandwich panel and its profiled facing. Finally, practical concluding remarks are given. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Lightweight cladding Sandwich panel (beam) Thick face Global static analysis computational algorithm Distribution calculus

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Constructing oscillation preventing scheme for advection equation by rational function

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COMPUTER PHYSICS COMMUNICATIONS 1996年第1期93卷 1-12页

作者： Xiao, F Yabe, T Ito, T TOKYO INST TECHNOL GRAD SCH NAGATSUTA DEPT ENERGY SCI MIDORI KU YOKOHAMA KANAGAWA 227 JAPAN

A numerical scheme for solving advection equations is presented. The scheme is derived from a rational interpolation function. Some properties of the scheme with respect to convex-concave preserving and monotone preserving are discussed. We find that the scheme is attractive in suppressing overshoots and undershoots even in the vicinities of discontinuity. The scheme can also be easily switched as the CIP (Cubic interpolated Pseudo-Particle) method to get a third-order accuracy in smooth region. Numbers of numerical tests are carried out to show the non-oscillatory and less diffusive nature of the scheme.

关键词： computational algorithm advection equation rational function monotone preserving scheme

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