Numerically efficient determination of the return loss of cavities using a finite difference eigenmode solver and modal analysis

2003 ◽  
Author(s):  
A. Jostingmeier ◽  
T. Meyer ◽  
A.S. Omar ◽  
M. Dohlus
Keyword(s):  
Finite Difference ◽  
Modal Analysis ◽  
Return Loss

Investigation of Impact Profile and Isolation Effect in Automated Impact Device Design and Control for Operational Modal Analysis

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Z. C. Ong ◽  
C. C. Lee
Keyword(s):  
Modal Analysis ◽  
Isolation Effect ◽  
Time Averaging ◽  
Impact Device ◽  
Lack Of Information ◽  
Analysis Technique ◽  
And Control ◽  
Phase Angles ◽  
Synchronous Time

A novel modal analysis technique called impact-synchronous modal analysis (ISMA) was introduced in previous research. With the utilization of impact-synchronous time averaging (ISTA), this modal analysis can be performed in presence of ambient forces whereas the conventional analysis method requires machines to be totally shut down. However, lack of information of phase angles with respect to impact in ISMA has caused it to be labor-intensive and time-consuming. An automated impact device (AID) is introduced in this study in the effort to replace the manually operated impact hammer and prepare it to be used in the current practice of ISMA on the purpose of enhancing its effectiveness and practicability. Impact profile and isolation effect are noted to be the contributing parameters in this study. This paper devoted on calibrating and controlling of the AID which gives the desired impact profiles as compared to the manual impact hammer. The AID is found effective in the determination of dynamic characteristics when the device is isolated from the boundary condition of the test structure.

Water quality of the Beli Lom river

1999 ◽  
Vol 39 (8) ◽  
pp. 55-62 ◽  
Author(s):  
Anastasios I. Stamou ◽  
Bogdana Koumanova ◽  
Stoyan Stoyanov ◽  
Georgy Atanasov ◽  
Konstantinos Pipilis
Keyword(s):  
Water Quality ◽  
Wastewater Treatment ◽  
Finite Difference ◽  
Treatment Plant ◽  
Quality Characteristics ◽  
Order Model ◽  
The Third ◽  
Do Concentration

A general methodology for the study of water quality in rivers is presented. The paper consists of four parts. In the first part the general characteristics of the area of study, which is the Beli Lom river, and its major pollution sources are presented. The effluent of the Razgrad Wastewater Treatment Plant (RWWTP) has been identified as the most significant pollution point source, due to the inadequate performance of the plant. The second part deals with data collection and processing. Four series of data have been collected, including physical, flow and water quality characteristics. In the third part a 1-d, finite-difference, second-order model is presented. In the fourth part, the model is calibrated, for the determination of its main coefficients, and is successfully verified by predicting the BOD and DO concentrations in the Beli Lom river for all series of data. Finally, the model has been applied to determine the maximum BOD and minimum DO effluent concentrations of the RWWTP, so that a minimum DO concentration is maintained throughout the river.

scholarly journals Multivariate Distributions in Hydrology and River Regulation

1976 ◽  
Vol 7 (5) ◽  
pp. 265-280
Author(s):  
N.A. Kartvelishvili ◽  
L.T. Gottschalk
Keyword(s):  
Markov Process ◽  
Finite Difference ◽  
Difference Scheme ◽  
River Runoff ◽  
Finite Difference Scheme ◽  
River Regulation ◽  
Distribution Functions ◽  
Multivariate Distributions ◽  
Model Order

It is assumed that the river runoff process can be approximated by a Markov process. The process is thus described by M distribution functions: Fn (qt, t ; qt-1; t-1;…;qt-n, t-n), t ≡ 1, 2, …, M where M is the number of time intervals within the year, n - the order of the Markov process and qt, in general, is a vector representing runoff at several sites in a river or neighbouring rivers. Fundamental hypothesis of relations between multivariate distributions and corresponding marginal distributions is given. A finite difference scheme for multisite and multilag generation of river runoff is derived. The derivation is based on the multivariate normal distribution. Different methods for determination of the order of the finite difference scheme are discussed as well as the influence of model order and method of parameter estimation on properties of the model.

scholarly journals Determining the Geometrical Sizes of Plates with Internal Hinges by Using Additional Conditions

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Vildan Yazıcı ◽  
Zahir Muradoğlu
Keyword(s):  
Finite Difference ◽  
Boundary Conditions ◽  
Difference Equations ◽  
Transmission Conditions ◽  
Elastic Plates ◽  
Different Boundary Conditions ◽  
Mechanical Constraints ◽  
Finite Difference Equations ◽  
The Common

For a system obtained by placing more than two elastic plates side by side, the transmission conditions are obtained at the common boundaries. Finite difference equations are developed for the problem of plates with internal hinges and applied for determination of the response of a system assembled from three different plates with different mechanical constraints between adjacent plates in this study. An algorithm is written to find out how long the size of the plates should be in order to obtain the desired amount of bending against the force affecting the system under different boundary conditions. The bisection and multigrid methods are used for this. These two methods are compared based on the obtained data.

Determination of orthotropic bone elastic constants using FEA and modal analysis

2002 ◽  
Vol 35 (6) ◽  
pp. 767-773 ◽  
Author(s):  
W.R. Taylor ◽  
E. Roland ◽  
H. Ploeg ◽  
D. Hertig ◽  
R. Klabunde ◽  
...  
Keyword(s):  
Modal Analysis ◽  
Elastic Constants
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