A Novel Technique for Analyzing Hydraulic Transients by Method of Characteristics

2003 ◽  
Author(s):  
Jianing Pu
Keyword(s):  
Numerical Experiments ◽  
Method Of Characteristics ◽  
Numerical Accuracy ◽  
Hydraulic Transients ◽  
Time Saving ◽  
Simulation Accuracy ◽  
Novel Technique ◽  
The Common ◽  
Usage Flexibility ◽  
Computation Speed

In analyzing hydraulic transients in complex pipeline systems by method of characteristics, existing approaches can not be fully satisfactory regard to numerical accuracy, computation speed, and application flexibility and simplicity. Trying to overcome this shortcomings, the paper puts forward a novel technique: in node computations, variable time steps are used, the common for boundaries and the different for lines; in every computation cycle, analyses of boundary nodes are always prior to that of interior ones, while simulation times of interior nodes are always prior to that of boundary ones; in solution of boundaries, only interpolation is used. Explanations and numerical experiments demonstrate its usage flexibility and simplicity, simulation accuracy, and executing time saving. It is specially suitable to analyses of complex systems.

scholarly journals Methodology for Neural Network-Based Material Card Calibration Using LS-DYNA MAT_187_SAMP-1 Considering Failure with GISSMO

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 643
Author(s):  
Paul Meißner ◽  
Jens Winter ◽  
Thomas Vietor
Keyword(s):  
Neural Network ◽  
Machine Learning ◽  
Rate Dependency ◽  
Material Parameter Identification ◽  
General Applicability ◽  
Time Saving ◽  
Test Dataset ◽  
The Common ◽  
Computationally Intensive ◽  
Tension Compression Asymmetry

A neural network (NN)-based method is presented in this paper which allows the identification of parameters for material cards used in Finite Element simulations. Contrary to the conventionally used computationally intensive material parameter identification (MPI) by numerical optimization with internal or commercial software, a machine learning (ML)-based method is time saving when used repeatedly. Within this article, a self-developed ML-based Python framework is presented, which offers advantages, especially in the development of structural components in early development phases. In this procedure, different machine learning methods are used and adapted to the specific MPI problem considered herein. Using the developed NN-based and the common optimization-based method with LS-OPT, the material parameters of the LS-DYNA material card MAT_187_SAMP-1 and the failure model GISSMO were exemplarily calibrated for a virtually generated test dataset. Parameters for the description of elasticity, plasticity, tension–compression asymmetry, variable plastic Poisson’s ratio (VPPR), strain rate dependency and failure were taken into account. The focus of this paper is on performing a comparative study of the two different MPI methods with varying settings (algorithms, hyperparameters, etc.). Furthermore, the applicability of the NN-based procedure for the specific usage of both material cards was investigated. The studies reveal the general applicability for the calibration of a complex material card by the example of the used MAT_187_SAMP-1.

Novel Glucose Biosensor Based on the Microcantilever

2003 ◽  
Vol 776 ◽  
Author(s):  
Jianhong Pei ◽  
Fang Tian ◽  
Thomas Thundat
Keyword(s):  
Glucose Biosensor ◽  
Enzyme Specificity ◽  
Biologically Relevant ◽  
Novel Technique ◽  
Novel Technology ◽  
Physical Chemical ◽  
Wide Range ◽  
Cantilever Surface ◽  
The Common ◽  
Detection Schemes

AbstractWe report a novel technique for micromechanical detection of biologically relevant glucose by immobilization of glucose oxidase (GOx) onto a microcantilever surface. Microfabricated cantilevers have recently attracted considerable interest in the development of a wide range of novel physical, chemical, and biological sensors. This paper describes the combination of this novel technology with enzyme specificity to construct a highly selective glucose biosensor. The enzyme-functionalized microcantilever undergoes bending due to a change in surface stress induced by the reaction between glucose and the GOx immobilized on the cantilever surface. The common interferents for glucose detection in other detection schemes have been tested and have shown no effect on the measurement of blood glucose level by this technique.

Simulation of growth and development of diverse legume species in APSIM

2002 ◽  
Vol 53 (4) ◽  
pp. 429 ◽  
Author(s):  
M. J. Robertson ◽  
P. S. Carberry ◽  
N. I. Huth ◽  
J. E. Turpin ◽  
M. E. Probert ◽  
...  
Keyword(s):  
Growth And Development ◽  
Independent Set ◽  
Sowing Date ◽  
Legume Species ◽  
Physiological Basis ◽  
Simulation Accuracy ◽  
Crop Models ◽  
Medicago Sativa L ◽  
The Common ◽  
The Tropics

This paper describes the physiological basis and validation of a generic legume model as it applies to 4 species: chickpea (Cicer arietinum L.), mungbean (Vigna radiata (L.) Wilczek), peanut (Arachis hypogaeaL.), and lucerne (Medicago sativa L.). For each species, the key physiological parameters were derived from the literature and our own experimentation. The model was tested on an independent set of experiments, predominantly from the tropics and subtropics of Australia, varying in cultivar, sowing date, water regime (irrigated or dryland), row spacing, and plant population density. The model is an attempt to simulate crop growth and development with satisfactory comprehensiveness, without the necessity of defining a large number of parameters. A generic approach was adopted in recognition of the common underlying physiology and simulation approaches for many legume species. Simulation of grain yield explained 77, 81, and 70% of the variance (RMSD = 31, 98, and 46 g/m2) for mungbean (n = 40, observed mean = 123 g/m2), peanut (n = 30, 421 g/m2), and chickpea (n = 31, 196 g/m2), respectively. Biomass at maturity was simulated less accurately, explaining 64, 76, and 71% of the variance (RMSD = 134, 236, and 125 g/m2) for mungbean, peanut, and chickpea, respectively. RMSD for biomass in lucerne (n = 24) was 85 g/m2 with an R2 of 0.55. Simulation accuracy is similar to that achieved by single-crop models and suggests that the generic approach offers promise for simulating diverse legume species without loss of accuracy or physiological rigour.

scholarly journals Balloon-assisted insertion of a cholangioscope into the common bile duct: a novel technique

Endoscopy ◽  
2008 ◽  
Vol 40 (S 02) ◽  
pp. E106-E107 ◽  
Author(s):  
A. Mori ◽  
H. Tatebe ◽  
N. Ohashi ◽  
T. Maruyama ◽  
K. Sakai ◽  
...  
Keyword(s):  
Bile Duct ◽  
Common Bile Duct ◽  
Novel Technique ◽  
The Common

scholarly journals A Phase-Fitted and Amplification-Fitted Explicit Runge–Kutta–Nyström Pair for Oscillating Systems

2021 ◽  
Vol 26 (3) ◽  
pp. 59
Author(s):  
Musa Ahmed Demba ◽  
Higinio Ramos ◽  
Poom Kumam ◽  
Wiboonsak Watthayu
Keyword(s):  
Stability Analysis ◽  
Numerical Experiments ◽  
Order Of Convergence ◽  
Truncation Error ◽  
Local Truncation Error ◽  
Nyström Methods ◽  
Oscillating Systems ◽  
The Common ◽  
Runge Kutta ◽  
The Stability

An optimized embedded 5(3) pair of explicit Runge–Kutta–Nyström methods with four stages using phase-fitted and amplification-fitted techniques is developed in this paper. The new adapted pair can exactly integrate (except round-off errors) the common test: y″=−w2y. The local truncation error of the new method is derived, and we show that the order of convergence is maintained. The stability analysis is addressed, and we demonstrate that the developed method is absolutely stable, and thus appropriate for solving stiff problems. The numerical experiments show a better performance of the new embedded pair in comparison with other existing RKN pairs of similar characteristics.

scholarly journals Calculation of the horizontal two-dimensional unsteady flows by the method of characteristics

2003 ◽  
Vol 25 (1) ◽  
pp. 49-64
Author(s):  
Tran Gia Lich ◽  
Nguyen Minh Son ◽  
Le Viet Cuong
Keyword(s):  
Numerical Experiments ◽  
Method Of Characteristics ◽  
Unsteady Flows ◽  
Equation System ◽  
Characteristic Form ◽  
Two Dimensional ◽  
The Method Of Characteristics ◽  
Venant Equation

This paper will be concerned with the characteristic form of the two dimensional Saint-Venant equation system, the supplementary equations at the boundaries, the methods of characteristics for solving the equation system and some numerical experiments.

A Robust WENO Type Finite Volume Solver for Steady Euler Equations on Unstructured Grids

2011 ◽  
Vol 9 (3) ◽  
pp. 627-648 ◽  
Author(s):  
Guanghui Hu ◽  
Ruo Li ◽  
Tao Tang
Keyword(s):  
Euler Equations ◽  
Finite Volume ◽  
Numerical Experiments ◽  
Unstructured Grids ◽  
Numerical Accuracy ◽  
Shock Region ◽  
Smooth Region ◽  
Type Reconstruction ◽  
Numer Math ◽  
Numerical Strategy

AbstractA recent work of Li et al. [Numer. Math. Theor. Meth. Appl., 1(2008), pp. 92-112] proposed a finite volume solver to solve 2D steady Euler equations. Although the Venkatakrishnan limiter is used to prevent the non-physical oscillations nearby the shock region, the overshoot or undershoot phenomenon can still be observed. Moreover, the numerical accuracy is degraded by using Venkatakrishnan limiter. To fix the problems, in this paper the WENO type reconstruction is employed to gain both the accurate approximations in smooth region and non-oscillatory sharp profiles near the shock discontinuity. The numerical experiments will demonstrate the efficiency and robustness of the proposed numerical strategy.

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