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A technical note: Theory of spontaneous versus induced capillary imbibition

TRANSPORT IN POROUS MEDIA 2001年第3期44卷 591-598页

作者： Rose, W Illini Technologists Int Champaign IL 61825 USA

The prevailing current wisdom about how to properly formulate an algorithm to describe spontaneous and coupled spontaneous/induced capillary imbibition into and through the interstices of porous Darcian scale sediments implies, but perhaps incorrectly, that the early empirical relations of Buckley and Leverett (1942) can safely be employed. Here this persistently popular point of view is found to be inadequate since it overlooks taking into full account how common sense suggests that it is surface energy gradient driving forces which are the underlying cause for the occurrences of these processes. Specifically it will be noted that a satisfactory algorithm to model cases where spontaneous capillary imbibition occurs will not be one which ignores the fact that necessarily the local free surface energy is continuously diminished in magnitude until a minimum value together with a maximum entropy condition has been reached. Hence, the conclusion is drawn herein that the Buckley-Leverett formulations alone at best can only be used to describe what is called those induced capillary imbibition processes caused by the action of mechanical energy driving forces.

关键词： spontaneous induced imbibition processes surface energy driving forces coupling effects simulation algorithms

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Predicting wellbore dynamics in a steam-assisted gravity drainage system: Numeric and semi-analytic model, and validation

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APPLIED THERMAL ENGINEERING 2015年 91卷 679-686页

作者： Sivaramkrishnan, Kaushik Huang, Biao Jana, Amiya K. Indian Inst Technol Energy & Proc Engn Lab Dept Chem Engn Kharagpur 721302 W Bengal India Univ Alberta Dept Chem & Mat Engn Edmonton AB T6G 2V4 Canada

Steam injection is an integral and a crucial element of the steam-assisted gravity drainage (SAGD) process that has emerged as a leading technology to recover heavy crude oil from oil sands. In this contribution, we have developed a simulation algorithm for an unsteady state nonisothermal two-phase wellbore model to predict the downward flow of a wet steam. This numeric model is reconstructed by incorporating the mass and energy conservation equations, and a pressure drop relationship, along with a couple of algebraic equations/correlations. A drift-flux model is used to consider the slipping occurred between the phases inside the wellbore. Further, the existence of four flow regimes in the wellbore is also taken into account. This dynamic wellbore flow model is attempted to simulate by developing a numerical algorithm. Furthermore, an analytical expression for wellbore pressure is determined to derive a semi-analytic model. Formulating a computer-assisted simulation algorithm for this, it is shown that the semi-analytic model offers a reduced complexity and computational time over the numeric model. A series of numerical and analytical results are presented to validate the wellbore models against the real field data. Subsequently, both the models are extended to predict the transient behavior of the steam injection system. It is investigated that both the solution methods provide similar results. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Steam injection well Dynamic model Numeric and semi-analytic structures simulation algorithms Validation Wellbore dynamics

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Power Lindley distribution and associated inference

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COMPUTATIONAL STATISTICS & DATA ANALYSIS 2013年 64卷 20-33页

作者： Ghitany, M. E. Al-Mutairi, D. K. Balakrishnan, N. Al-Enezi, L. J. Kuwait Univ Fac Sci Dept Stat & Operat Res Safat 13060 Kuwait McMaster Univ Dept Math & Stat Hamilton ON L8S 4K1 Canada

A new two-parameter power Lindley distribution is introduced and its properties are discussed. These include the shapes of the density and hazard rate functions, the moments, skewness and kurtosis measures, the quantile function, and the limiting distributions of order statistics. Maximum likelihood estimation of the parameters and their estimated asymptotic standard errors are derived. Three algorithms are proposed for generating random data from the proposed distribution. A simulation study is carried out to examine the bias and mean square error of the maximum likelihood estimators of the parameters as well as the coverage probability and the width of the confidence interval for each parameter. An application of the model to a real data set is presented finally and compared with the fit attained by some other well-known two-parameter distributions. (c) 2013 Elsevier B.V. All rights reserved.

关键词： Power Lindley distribution Maximum likelihood estimator simulation algorithms Lambert function

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On the computational power of WECPAR

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JOURNAL OF SUPERCOMPUTING 2015年第1期71卷 28-44页

作者： El-Boghdadi, Hatem M. Cairo Univ Fac Engn Dept Comp Engn Giza 12211 Egypt

Reconfigurable models were shown to be very powerful in solving many problems faster than non-reconfigurable models. WECPAR is an reconfigurable model that has point-to-point reconfigurable interconnection with wires between neighboring processors. This paper studies several aspects of WECPAR. We first consider solving the list ranking problem on WECPAR. Some of the results obtained show that, ranking one element in a list of elements can be solved on WECPAR in time. Also, on , ranking a list of elements can be done in time. Then, we assess the relative computational power of WECPAR and transfer a large body of algorithms to work directly on WECPAR. We introduce several simulation algorithms between WECPAR and well-known models such as PRAM and RMBM. simulation algorithms show that a PRIORITY CRCW PRAM of processors and shared memory locations can be simulated on WECPAR in time. Also, we show that a PRIORITY CRCW basic RMBM(, of processors and buses can be simulated on WECPAR in time. This directly migrate a large number of algorithms to work on WECPAR with the simulation overhead.

关键词： Parallel algorithms simulation algorithms List ranking

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Multiparameter time-domain sensitivity computation

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-FUNDAMENTAL THEORY AND APPLICATIONS 2001年第11期48卷 1296-1307页

作者： Daldoss, L Gubian, P Quarantelli, M Carnegie Mellon Univ Dept Elect & Comp Engn Pittsburgh PA 15213 USA Univ Brescia Dept Elect Automat Brescia Italy PDF Solut Inc Italian Off Desenzano Del Garda Italy

In this paper, a novel approach for the computation of multiparameter time-domain sensitivity during circuit simulation is presented. The computation of the sensitivity values of one or more circuit variables (e.g., node voltages or branch currents) with respect to both design parameters (e.g., R, C, MOS length, MOS width...) and process parameters (e.g., tox, nsub, u0...) is addressed by introducing a rigorous mathematical derivation of the proposed direct differentiation modified algorithm (DDMA). First, the circuit interpretation of the analytical formulas as well as their theoretical derivation from the Tellegen's theorem is discussed. Then, DDMA is compared with the direct method and the adjoint technique to emphasize the cost difference in terms of CPU operations. The accuracy of the new algorithm is also evaluated, by estimating the numerical error involved in the solution of discretized sensitivity equations. Finally, a set of circuit examples is presented to demonstrate the effectiveness of DDMA together with the implementation details needed to include the present sensitivity analysis in a circuit simulator such as Spice3F5.

关键词： computational methods sensitivity analysis simulation algorithms

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A mathematical study of the evolution of fouling and operating parameters throughout membrane sheets comprising spiral wound modules

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CHEMICAL ENGINEERING JOURNAL 2012年 187卷 222-231页

作者： Kostoglou, Margaritis Karabelas, Anastasios J. Ctr Res & Technol Hellas Chem Proc Engn Res Inst GR-57001 Thermi Greece Aristotle Univ Thessaloniki Dept Chem Div Chem Technol Thessaloniki Greece

Local experimental data on key process parameters, throughout membrane sheets of spiral-wound membrane (SWM) elements, are unavailable and very difficult to obtain;therefore, theoretical models are essential to better understand the evolution of fouling, which is helpful for improving design and operation of these modules. The mathematical model, formulated in a fundamental manner herein, takes into account the spatial flow field non-uniformities inside narrow channels with spacers (simulating SWM elements) and their interaction with the evolving deposits. A realistic meso-scale transient model, typical of the early stages of organic membrane fouling, is employed. Appropriate non-dimensionalization of model equations allows to treat separately the two (practically significant) cases of constant inlet pressure and constant average permeate flux. Several simplified cases are examined, for specific dimensionless parameter values, and asymptotic solutions are derived. The results of this analysis have guided the development of very efficient numerical techniques, most useful for future extensions towards the development of a comprehensive modeling tool, appropriate for module design calculations and for assessing detailed experimental data. (C) 2012 Elsevier B.V. All rights reserved.

关键词： Fouling spatial and temporal evolution on membrane sheets Spiral wound membrane modules Theoretical analysis simulation algorithms

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No-race charge-recycling complementary pass transistor logic

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IEE PROCEEDINGS-COMPUTERS AND DIGITAL TECHNIQUES 2004年第3期151卷 183-190页

作者： Abbasian, A Rasouli, SH Afzali-Kusha, A Nourani, M Univ Tehran Dept Elect & Comp Engn IC Design Lab Tehran Iran Univ Texas Dept Elect Engn Richardson TX 75083 USA

A logic family called no-race charge-recycling complementary pass transistor logic (NCRCPL) is proposed. The use of a new regenerator in NCRCPL leads to a complete elimination of the controller in the circuit hence reducing the number of transistors and power consumption. It has an additional benefit of reduced sensitivity to signal skew. The proposed logic family in its modular structure also has a better performance than previous modular structures based on charge recycling. Furthermore, a latch structure called dual-rail isolated latch which can be used for pipelining NCRCPL has been proposed. The new latch had a much better performance compared with previous static latch structures. To enhance the power efficiency of the pipeline configuration an event-detector circuit is proposed that may reduce the power consumption by up to 50% compared with previous pipeline configurations. To assess the performance improvements of the logic structures of this work compared with other charge recycling logic structures, logic gates and ripple carry adders are studied.

关键词： Logic programming theory forced simulation simulation algorithms industrial property refinement algorithms intellectual property core reuse automatic intellectual property matching device driver logic programming programmable intellectual property Data handling techniques intellectual property matching tool string matching tabled logic programming environment tabled logic programming-based IP matching algorithm Formal methods formal verification bisimulation algorithms adaptability checking

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A Unifying Mathematical Definition of Particle Methods

IEEE OPEN JOURNAL OF THE COMPUTER SOCIETY

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IEEE OPEN JOURNAL OF THE COMPUTER SOCIETY 2023年第1期4卷 97-108页

作者： Pahlke, Johannes Sbalzarini, Ivo F. Tech Univ Dresden Fac Comp Sci D-01187 Dresden Germany Max Planck Inst Mol Cell Biol & Genet D-01307 Dresden Germany Ctr Syst Biol Dresden D-01307 Dresden Germany Tech Univ Dresden Cluster Excellence Phys Life D-01307 Dresden Germany Ctr Scalable Data Analyt & Artificial Intelligence D-01187 Dresden Germany

Particle methods are a widely used class of algorithms for computer simulation of complex phenomena in various fields, such as fluid dynamics, plasma physics, molecular chemistry, and granular flows, using diverse simulation methods, including Smoothed Particle Hydrodynamics (SPH), Particle-in-Cell (PIC) methods, Molecular Dynamics (MD), and Discrete Element Methods (DEM). Despite the increasing use of particle methods driven by improved computing performance, the relation between these algorithms remains formally unclear, and a unifying formal definition of particle methods is lacking. Here, we present a rigorous mathematical definition of particle methods and demonstrate its importance by applying it to various canonical and non-canonical algorithms, using it to prove a theorem about multi-core parallelizability, and designing a principled scientific computing software based on it. We anticipate that our formal definition will facilitate the solution of complex computational problems and the implementation of understandable and maintainable software frameworks for computer simulation.

关键词： Algorithmics formal definition mesh-free methods particle methods simulation algorithms parallelization software engineering

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Proven Distributed Memory Parallelization of Particle Methods

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ACM TRANSACTIONS ON PARALLEL COMPUTING 2024年第4期11卷 1-45页

作者： Pahlke, Johannes Sbalzarini, Ivo f. Tech Univ Dresden Fac Comp Sci Dresden Germany Max Planck Inst Mol Cell Biol & Genet Ctr Syst Biol Dresden Dresden Germany

We provide a mathematically proven parallelization scheme for particle methods on distributed-memory computer systems. Particle methods are a versatile and widely used class of algorithms for computer simulations and numerical predictions in various applications, ranging from continuum fluid dynamics to discrete granular flows and molecular dynamics simulations. Particle methods naturally lend themselves to implementation on parallel computing systems. So far, however, a mathematical proof of correctness and equivalence to sequential implementations has only been available for shared-memory parallelism. Here, we leverage a formal definition of the algorithmic class of particle methods to provide a proven parallelization scheme for distributed-memory computers. We prove that thus parallelized particle methods on distributed-memory computers are formally equivalent to their sequential counterpart for a well-defined class of particle methods, and we provide analytical expressions for the speedup and scalability bounds of this class of algorithms in function of their parameters. The parallelization scheme analyzed here is the basis of many real-world software designs for parallel particle methods. The present analysis is, therefore, of direct relevance to existing and new parallel implementations of particle methods and places them on solid theoretical grounds, rationalizing best practices and providing useful scalability and speedup bounds for benchmarking.

关键词： Particle methods simulation algorithms formal definition algorithmics software engineering parallelization distributed memory meshfree methods scalability bounds

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Method to Model Vccin Feedthrough Noise in Multi-Domain Fully Integrated Voltage Regulators 27

Method to Model Vccin Feedthrough Noise in Multi-Domain Full...

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27th IEEE Conference on Electrical Performance on Electronic Packaging and Systems (EPEPS)

作者： Govindan, Srinivasan Bharath, Krishna Gope, Dipanjan Venkataraman, Srikrishnan Intel Technol India Pvt Ltd Scalable Performance CPU Dev Grp Bangalore Karnataka India Intel Corp Assembly Test & Technol Dev Chandler AZ 85226 USA Indian Inst Sci Dept Elect Commun Engn Bangalore Karnataka India

ISBN: (纸本)9781538651667

The on-chip power supply domains of high performance server microprocessors are generated using built-in switching voltage regulators (also know as Fully Integrated Voltage regulators-FIVRs). The advantages of integrated voltage generation are improved performance and reduced platform cost. However, the FIVRs share a common input power plane in the package and the coupling of noise between FIVRs is of significant concern. This noise is also known as the Vccin feedthrough noise. The modeling of the vccin feedthrough noise using circuit simulation tools such as SPICE is a laborious and time consuming task. This paper proposes a simple method to accurately predict the vccin feedthrough noise based on the state-space averaged small signal method. This method simplifies the modeling of vccin feedthrough noise and saves lot of time and effort.

关键词： Power integrity and power distribution networks Electromagnetic (EM) and EM interference modeling simulation algorithms tools flows Electronic packages and microsystems

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