scholarly journals On some numerical methods for solving the 1-D Saint-Venant equations of general flow regime. Part 2: Verification and application

2003 ◽  
Vol 25 (1) ◽  
pp. 26-38 ◽  
Author(s):  
Nguyen Van Hanh ◽  
Nguyen Van Diep ◽  
Ngo Huy Can
Keyword(s):  
Numerical Methods ◽  
Flow Regime ◽  
Test Problems ◽  
Preliminary Evaluation ◽  
Source Terms ◽  
Mathematical Transformation ◽  
General Flow ◽  
Saint Venant Equations ◽  
Mixed Approach ◽  
Better Than

In the Part 1 of this paper [1], some numerical methods for solving the 1-D Saint-Venant equations of general flow regime have been described. This Part of the paper presents the results of verification by various test problems, covering all of three flow regimes: sub-, trans-, and super-critical. The results show that the mixed approach (between pointwise and upwind) for source terms is better than the pointwise one and any mathematical transformation of source terms must be careful, since that can lead to nonphysical solutions. The Roe's approximation with the mixed technique for the source terms is used for a preliminary evaluation of the Son La - Hoa Binh dambreak problem

scholarly journals On some numerical methods for solving the 1-D Saint-Venant equations of general flow regime. Part 1: Numerical methods

2002 ◽  
Vol 24 (4) ◽  
pp. 236-248
Author(s):  
Nguyen Van Hanh ◽  
Nguyen Van Diep ◽  
Ngo Huy Can
Keyword(s):  
Numerical Methods ◽  
Dam Break ◽  
Test Problems ◽  
Preliminary Evaluation ◽  
Source Terms ◽  
Research Groups ◽  
Saint Venant Equations ◽  
Mixed Approach ◽  
Selection Of ◽  
Better Than

Development of methods for numerical simulation of dike- or dam-break flood is one of essential problems of Fluid Mechanics at the present time. Many numerical methods for solving the 1-D Saint-Venant equations have been proposed. However, the analysis, the evaluation and the selection of appropriate and efficient methods are interest of many research groups and institutions in the world. The purpose of this paper is to introduce and to evaluate four numerical methods for solving the 1-D homogenous Saint-Venant equations in combination with three approaches of processing source terms. The evaluation is based on the test problems, proposed by European Hydraulic Research Laboratories. The Part 1of the paper presents some modern numerical methods for solving the 1-D Saint-Venant equations of general Bow regime, where the Bow may be mixed between sub­ critical and supercritical. The homogenous part of the system of equations is numerically solved by "shock capturing methods" for conservation laws: the Lax-Friedrichs, the self adjusting hybrid, the Roe's approximation and the Nessyahu-Tedmor methods. The source terms play an important role and are discretized by the pointwise, upwind or mixed approaches. In the second part of this paper the above methods are verified by a set of test problems, covering all of three flow regimes: subcritical, supercritical, transcritical. The re­sults show that the mixed approach of processing source terms is better than the pointwise one. The Roe approximation method with the mixed discretization of source terms is then applied for a preliminary evaluation of the Son La - Hoa Binh dam-break problem.

Improved Trust Region Based MPS Method for High-Dimensional Expensive Black-Box Problems

2013 ◽  
Author(s):  
George H. Cheng ◽  
Adel Younis ◽  
Kambiz Haji Hajikolaei ◽  
G. Gary Wang
Keyword(s):  
Optimization Problems ◽  
Trust Region ◽  
Black Box ◽  
High Dimensional ◽  
Test Problems ◽  
Design Variables ◽  
Low Dimensionality ◽  
Improve Algorithm ◽  
Improved Performance ◽  
Better Than

Mode Pursuing Sampling (MPS) was developed as a global optimization algorithm for optimization problems involving expensive black box functions. MPS has been found to be effective and efficient for problems of low dimensionality, i.e., the number of design variables is less than ten. A previous conference publication integrated the concept of trust regions into the MPS framework to create a new algorithm, TRMPS, which dramatically improved performance and efficiency for high dimensional problems. However, although TRMPS performed better than MPS, it was unproven against other established algorithms such as GA. This paper introduces an improved algorithm, TRMPS2, which incorporates guided sampling and low function value criterion to further improve algorithm performance for high dimensional problems. TRMPS2 is benchmarked against MPS and GA using a suite of test problems. The results show that TRMPS2 performs better than MPS and GA on average for high dimensional, expensive, and black box (HEB) problems.

Assessment of Bentazon Tolerance in Pepper (Capsicumsp.)

1989 ◽  
Vol 3 (2) ◽  
pp. 307-312 ◽  
Author(s):  
Howard F. Harrison ◽  
Richard L. Fery
Keyword(s):  
Plant Breeding ◽  
Field Experiments ◽  
Sweet Pepper ◽  
Hot Pepper ◽  
Preliminary Evaluation ◽  
Susceptible Cultivar ◽  
High Degree ◽  
Breeding Techniques ◽  
Better Than

Preliminary evaluation of 11 pepper genotypes indicated a high degree of variability in bentazon tolerance. ‘Bohemian Chile’ and ‘Santanka’ hot pepper tolerated bentazon similarly in subsequent greenhouse and field experiments. Yields or shoot fresh weights of these two cultivars were not reduced by up to 9.0 kg ai/ha bentazon in the field. ‘Keystone Resistant Giant’ sweet pepper was more susceptible to bentazon compared to the tolerant cultivars, but it was more tolerant than the highly susceptible cultivar, ‘Sweet Banana’. An F1hybrid of Keystone Resistant Giant and Santanka tolerated bentazon better than Keystone Resistant Giant but slightly less than Santanka. Thus, bentazon tolerance in this genotype is genetically transferrable, and increasing bentazon tolerance through conventional plant breeding techniques may be possible.

scholarly journals A comparison of sleep, depressive symptoms, and parental perceptions between U.S. and Taiwan adolescents with self-reported sleep problems

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Ya-Ting Yang ◽  
Katherine A Kaplan ◽  
Jamie M Zeitzer
Keyword(s):  
United States ◽  
Depressive Symptoms ◽  
Sleep Problems ◽  
The United States ◽  
Preliminary Evaluation ◽  
Sleep Behavior ◽  
Behavioral Choices ◽  
Antecedents And Consequences ◽  
Inadequate Sleep ◽  
Better Than

Abstract Study Objectives Inadequate sleep is pervasive among teens worldwide, resulting in daytime sleepiness and, in some cases, depressive symptoms. In addition to their own behavioral choices, parent perceptions may also play a role in adolescent sleep. This study conducted a preliminary evaluation of the antecedents and consequences of sleep factors among adolescents in the United States and Taiwan. Methods Participants were adolescents with self-reported sleep concerns from academically similar schools in Taiwan (n = 548) and northern California, United States (n = 128). Questionnaires on sleep and mood were administered to both the teens and parents. Results While Taiwanese students’ self-reported sleep behavior was generally better than U.S. students (p < .01), Taiwanese students had higher overall self-reported sleepiness (p < .01). Furthermore, Taiwanese parents reported teen sleep durations of 6.53 ± .827 hours per night during the week (with 45% perceiving this as sufficient), while U.S. parents reported teen sleep durations of 7.22 ± .930 hours (with 27% perceiving this as sufficient). Adolescents in both cohorts had high levels of symptoms consistent with depression (Taiwan: 70%, United States: 62%), which was associated with shorter sleep times for both cohorts and evening chronotype in the Taiwanese, but not U.S., adolescents. Conclusions Some differences exist between Taiwanese and U.S. adolescents, with generally better sleep and less sleepiness reported among students in the United States, and Taiwanese students’ sleep influenced more strongly by chronotype. Furthermore, Taiwanese parents reported less concern about their child’s insufficient sleep, despite the fact that inadequate sleep is strongly associated with depressive symptoms for both cohorts.

Evaluation of Unsteady CFD Methods by Their Application to a Transonic Propfan Stage

2001 ◽  
Author(s):  
S. Schmitt ◽  
F. Eulitz ◽  
L. Wallscheid ◽  
A. Arnone ◽  
M. Marconcini
Keyword(s):  
Numerical Methods ◽  
Navier Stokes ◽  
Test Case ◽  
Flow Angle ◽  
Laser Measurements ◽  
General Flow ◽  
Blade Row ◽  
Flow Features ◽  
Blade Row Interaction ◽  
Good Agreement

The accuracy in predicting the unsteady aerodynamic blade-row-interaction of two state-of-the-art Navier-Stokes codes is evaluated within the current paper. The general flow features of the test case — a transonic research propfan stage — are described in brief as far as necessary to understand the detailed comparisons. The calculated unsteady velocity and flow angle distributions at various axial planes of the stage are compared to data from unsteady laser measurements. The general flow features of the propfan are very well reproduced by the numerical methods and a good agreement is also obtained in comparison to the measured data. One important outcome of the comparison is the good agreement of both numerical methods with the unsteady fluctuations measured in the experiment.

Numerical Methods for Two-Fluid Dispersive Fast MHD Phenomena

2011 ◽  
Vol 10 (1) ◽  
pp. 183-215 ◽  
Author(s):  
Bhuvana Srinivasan ◽  
Ammar Hakim ◽  
Uri Shumlak
Keyword(s):  
Wave Propagation ◽  
Numerical Methods ◽  
Discontinuous Galerkin ◽  
Equation System ◽  
Source Terms ◽  
Phase Errors ◽  
Wave Propagation Method ◽  
Fluid Equations ◽  
Runge Kutta ◽  
Two Fluid

AbstractThe finite volume wave propagation method and the finite element Runge-Kutta discontinuous Galerkin (RKDG) method are studied for applications to balance laws describing plasma fluids. The plasma fluid equations explored are dispersive and not dissipative. The physical dispersion introduced through the source terms leads to the wide variety of plasma waves. The dispersive nature of the plasma fluid equations explored separates the work in this paper from previous publications. The linearized Euler equations with dispersive source terms are used as a model equation system to compare the wave propagation and RKDG methods. The numerical methods are then studied for applications of the full two-fluid plasma equations. The two-fluid equations describe the self-consistent evolution of electron and ion fluids in the presence of electromagnetic fields. It is found that the wave propagation method, when run at a CFL number of 1, is more accurate for equation systems that do not have disparate characteristic speeds. However, if the oscillation frequency is large compared to the frequency of information propagation, source splitting in the wave propagation method may cause phase errors. The Runge-Kutta discontinuous Galerkin method providesmore accurate results for problems near steady-state aswell as problems with disparate characteristic speeds when using higher spatial orders.

scholarly journals A Simple and Efficient Technique to Generate Bounded Solutions for the Multidimensional Knapsack Problem: a Guide for OR Practitioners

2021 ◽  
Vol 15 ◽  
pp. 1650-1656
Author(s):  
Yun Lu ◽  
Bryan McNally ◽  
Emre Shively-Ertas ◽  
Francis J. Vasko
Keyword(s):  
Knapsack Problem ◽  
General Purpose ◽  
Test Problems ◽  
Bounded Solutions ◽  
Multidimensional Knapsack Problem ◽  
Multidimensional Knapsack ◽  
Np Hard Problem ◽  
Programming Software ◽  
Short Time ◽  
Better Than

The 0-1 Multidimensional Knapsack Problem (MKP) is a NP-Hard problem that has important applications in business and industry. Approximate solution approaches for the MKP in the literature typically provide no guarantee on how close generated solutions are to the optimum. This article demonstrates how general-purpose integer programming software (Gurobi) is iteratively used to generate solutions for the 270 MKP test problems in Beasley’s OR-Library such that, on average, the solutions are guaranteed to be within 0.094% of the optimums and execute in 88 seconds on a standard PC. This methodology, called the simple sequential increasing tolerance (SSIT) matheuristic, uses a sequence of increasing tolerances in Gurobi to generate a solution that is guaranteed to be close to the optimum in a short time. This solution strategy generates bounded solutions in a timely manner without requiring the coding of a problem-specific algorithm. The SSIT results (although guaranteed within 0.094% of the optimums) when compared to known optimums deviated only 0.006% from the optimums—far better than any published results for these 270 MKP test instances.

Efficient Parametric Optimization for Expensive Single Objective Problems

2021 ◽  
pp. 1-12
Author(s):  
Jonathan Weaver-Rosen ◽  
Richard Malak
Keyword(s):  
Adaptive Sampling ◽  
Parametric Optimization ◽  
Optimization Problems ◽  
Test Problems ◽  
Surface Model ◽  
High Fidelity ◽  
Unknown Parameters ◽  
Element Analysis ◽  
Better Than

Abstract Parametric optimization solves optimization problems as a function of uncontrollable or unknown parameters. Such an approach allows an engineer to gather more information than traditional optimization procedures during design. Existing methods for parametric optimization of computationally or monetarily expensive functions can be too time-consuming or impractical to solve. Therefore, new methods for the parametric optimization of expensive functions need to be explored. This work proposes a novel algorithm that leverages the advantages of two existing optimization algorithms. This new algorithm is called the efficient parametric optimization (EPO) algorithm. EPO enables adaptive sampling of a high-fidelity design space using an inexpensive low-fidelity response surface model. Such an approach largely reduces the required number of expensive high-fidelity computations. The proposed method is benchmarked using analytic test problems and used to evaluate a case study requiring finite element analysis. Results show that EPO performs as well as or better than the existing alternative, P3GA, for these problems given an allowable number of function evaluations.

An Improved Fuzzy C-Means Algorithm for Cell Formation Problems with Alternative Routes

2015 ◽  
Vol 4 (4) ◽  
pp. 15-30
Author(s):  
İhsan Erozan ◽  
Ozden Ustun ◽  
Orhan Torkul
Keyword(s):  
Manufacturing Systems ◽  
Cell Formation ◽  
Test Problems ◽  
Uncertain Information ◽  
Cellular Manufacturing Systems ◽  
Fuzzy C Means ◽  
Realistic Approach ◽  
Alternative Routes ◽  
Better Than ◽  
Improved Algorithm

Cell formation is one of the most important problems faced in designing cellular manufacturing systems. Fuzzy c-means (FCM) has been successfully used to solve a variety of the cell formation problems because it allows the representation of uncertain information. Many products or parts to be manufactured in the real world have alternative routes. To ignore the routes is not a realistic approach. However, most FCM approaches used to form a cellular system in the literature have ignored or avoided using the alternative routes because of its complexity. In this paper, an improved FCM algorithm has been proposed to overcome the computational complexity of the alternative routes. The improved algorithm presents an easy and practical way to solve the cell formation problems with alternative routes. An experiment was designed to test and compare the performance of the improved algorithm. The results of the experiment have shown that most of the obtained results are close to the test problems and better than the conventional crisp methods in the literature.

Tuned test problems for numerical methods in engineering

1997 ◽  
Vol 40 (22) ◽  
pp. 4183-4209 ◽  
Author(s):  
G. B. Sinclair ◽  
M. Anaya-Dufresne ◽  
G. Meda ◽  
M. Okajima
Keyword(s):  
Numerical Methods ◽  
Test Problems
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