scholarly journals Determination of VAR Compensator Placement for System Stability Improvement on Java Bali Network

2021 ◽  
Vol 1096 (1) ◽  
pp. 012133
Author(s):  
A E Apriyanto ◽  
A R Virgiawan ◽  
H Pariaman ◽  
M Hisjam ◽  
N Hariyanto
Keyword(s):  
System Stability

scholarly journals Determination of coupled sway, roll, and yaw motions of a floating body in regular waves

2004 ◽  
Vol 2004 (41) ◽  
pp. 2181-2197 ◽  
Author(s):  
S. N. Das ◽  
S. K. Das
Keyword(s):  
Dynamic Equilibrium ◽  
Numerical Models ◽  
Equations Of Motion ◽  
System Stability ◽  
Floating Body ◽  
Regular Waves ◽  
Laplace Transform Technique ◽  
Restoring Forces ◽  
The Waves

This paper investigates the motion response of a floating body in time domain under the influence of small amplitude regular waves. The governing equations of motion describing the balance of wave-exciting force with the inertial, damping, and restoring forces are transformed into frequency domain by applying Laplace transform technique. Assuming the floating body is initially at rest and the waves act perpendicular to the vessel of lateral symmetry, hydrodynamic coefficients were obtained in terms of integrated sectional added-mass, damping, and restoring coefficients, derived from Frank's close-fit curve. A numerical experiment on a vessel of19190ton displaced mass was carried out for three different wave frequencies, namely,0.56rad/s,0.74rad/s, and1.24rad/s. The damping parameters (ςi) reveal the system stability criteria, derived from the quartic analysis, corresponding to the undamped frequencies (βi). It is observed that the sway and yaw motions become maximum for frequency0.56rad/s, whereas roll motion is maximum for frequency0.74rad/s. All three motions show harmonic behavior and attain dynamic equilibrium for timet>100seconds. The mathematical approach presented here will be useful to determine seaworthiness characteristics of any vessel when wave amplitudes are small and also to validate complex numerical models.

scholarly journals Determination of Stability Correction Parameters for Dynamic Equations of Constrained Multibody Systems

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Lyu Guizhi ◽  
Liu Rong
Keyword(s):  
Numerical Simulation ◽  
Constraint Equation ◽  
System Stability ◽  
Dynamic Equations ◽  
Constraint Violation ◽  
Stability Parameters ◽  
Constraint Matrix ◽  
Stability Method ◽  
Parameter Values

When analyzing mechanical systems with numerical simulation by the Udwadia and Kalaba method, numerical integral results of dynamic equations will gradually deviate from requirements of constraint equations and eventually lead to constraint violation. It is a common method to solve the constraint violation by using constraint stability to modify the constraint equation. Selection of stability parameters is critical in the particular form of the corrected equation. In this paper, the method of selecting and determining of stability parameters is given, and these parameters will be used to correct the Udwadia-Kalaba basic equation by the Baumgarte constraint stability method. The selection domain of stability parameters is further reduced in view of the singularity of the constraint matrix during the integration procedure based on the selection domain which is obtained by the system stability analysis method. Errors of velocity violation and position violation are defined in the workspace, so as to determine the parameter values. Finally, the 3-link spatial manipulator is used to verify stability parameters of the proposed method. Numerical simulation results verify the effectiveness of the proposed method.

Power system stability with parallel active filter ensuring compensation of capacitive reactive power of a resonant LC circuit

2012 ◽  
Vol 60 (2) ◽  
pp. 353-361 ◽  
Author(s):  
T. Platek
Keyword(s):  
Reactive Power ◽  
Experimental Studies ◽  
Input Voltage ◽  
Active Filter ◽  
Current Control ◽  
System Stability ◽  
Stable Operation ◽  
Additional Measurement ◽  
Lc Circuit

Abstract. This paper presents an analysis allowing for the determination of the differential equation describing the circuit of the active filter inverter output current control with an additional measurement of input voltage. The resulting equation allows to determine the conditions that ensure stable operation of the filter with the load in form of a resonant LC circuit. Analysis results were confirmed by computer simulation and experimental studies of commercial active filter.

scholarly journals Deformation indeterminacy in global analysis of steel structures with semi-rigid joints

2020 ◽  
Vol 18 (3) ◽  
pp. 319-324
Author(s):  
Srdjan Zivkovic ◽  
Marija Spasojevic-Surdilovic ◽  
Marko Milosevic ◽  
Nenad Stojkovic
Keyword(s):  
Comparative Analysis ◽  
Global Analysis ◽  
Steel Structures ◽  
Steel Frame ◽  
System Stability ◽  
Deformation Method ◽  
Rigid Joints

This paper shows the procedure for determination of deformation indeterminacy within global analysis of steel constructions with semi-rigid joints, as well as the analysis of deformation indeterminacy within the approximate deformation method. In this paper there has been a detailed comparative analysis with criteria of cinematic system stability and division on steel frame with semi-rigid connections to systems with movable and immovable joints.

New reagent for colorimetric assay of calcium in serum

1993 ◽  
Vol 39 (9) ◽  
pp. 1820-1824 ◽  
Author(s):  
E Chapoteau ◽  
B P Czech ◽  
W Zazulak ◽  
A Kumar
Keyword(s):  
Atomic Absorption ◽  
Calibration Curve ◽  
Colorimetric Assay ◽  
Chelating Agent ◽  
Comparison Method ◽  
System Stability ◽  
Atomic Absorption Spectrophotometer ◽  
Tetracarboxylic Acid ◽  
The Mean

Abstract We report a new single-reagent colorimetric assay for the determination of calcium in serum. The assay is based on a novel chromogenic tetracarboxylic acid chelating agent. The method has several advantages over the o-cresolphthalein complexone (CPC) method, including improved linearity, better accuracy, increased stability, and lower working pH (9.0). The calibration curve for the assay is linear up to 4 mmol/L. The results for 47 patients' samples correlated well with results obtained with an Instrumentation Laboratory atomic absorption spectrophotometer. The mean (+/- SD) calcium values for the new method were 2.27 +/- 0.06 mmol/L and 2.26 +/- 0.05 mmol/L for the comparison method. The on-system stability of the reagents is 1 week vs 8 h for the CPC method.

Stability of Squeeze-Film-Damper Supported Flexible Rotors

1977 ◽  
Vol 99 (4) ◽  
pp. 545-551 ◽  
Author(s):  
M. D. Rabinowitz ◽  
E. J. Hahn
Keyword(s):  
Steady State ◽  
System Stability ◽  
Squeeze Film ◽  
Design Data ◽  
Flexible Rotors ◽  
Wide Range ◽  
Single Mass ◽  
The Stability ◽  
Rotor Mass

Assuming the short bearing approximation and symmetric motions, the stability of the steady-state synchronous operation of centrally preloaded single-mass flexible rotors supported in squeeze-film bearing dampers is theoretically investigated. The stability regions are depicted over a wide range of system parameters and allow for easy determination of the stability of existing steady-state design data. The influence of rotor flexibility, rotor speed, bearing dimensions, lubricant viscosity, rotor mass distribution, and rotor unbalance on rotor-bearing system stability may be readily seen. In the absence of pressurization, instability regions were possible even with relatively high support damping, though no instability was indicated for speeds below the support natural frequency, or for bearing eccentricity ratio <0.4 at any speed. Pressurization of the lubricant supply was found to stabilize the system over the whole range of parameters investigated, regardless of unbalance, which would then be limited only by the bearing clearance. Data are presented which enable the minimum supply pressure to ensure full film lubrication to be conveniently determined.

scholarly journals The CARMENES search for exoplanets around M dwarfs

2020 ◽  
Vol 636 ◽  
pp. A119 ◽  
Author(s):  
S. Stock ◽  
J. Kemmer ◽  
S. Reffert ◽  
T. Trifonov ◽  
A. Kaminski ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Radial Velocity ◽  
Model Comparison ◽  
Gaussian Process Regression ◽  
System Stability ◽  
M Dwarfs ◽  
Stellar Activity ◽  
Orbital Parameters ◽  
Orbital Periods

Context. The nearby ultra-compact multiplanetary system YZ Ceti consists of at least three planets, and a fourth tentative signal. The orbital period of each planet is the subject of discussion in the literature due to strong aliasing in the radial velocity data. The stellar activity of this M dwarf also hampers significantly the derivation of the planetary parameters. Aims. With an additional 229 radial velocity measurements obtained since the discovery publication, we reanalyze the YZ Ceti system and resolve the alias issues. Methods. We use model comparison in the framework of Bayesian statistics and periodogram simulations based on a method by Dawson and Fabrycky to resolve the aliases. We discuss additional signals in the RV data, and derive the planetary parameters by simultaneously modeling the stellar activity with a Gaussian process regression model. To constrain the planetary parameters further we apply a stability analysis on our ensemble of Keplerian fits. Results. We find no evidence for a fourth possible companion. We resolve the aliases: the three planets orbit the star with periods of 2.02 d, 3.06 d, and 4.66 d. We also investigate an effect of the stellar rotational signal on the derivation of the planetary parameters, in particular the eccentricity of the innermost planet. Using photometry we determine the stellar rotational period to be close to 68 d and we also detect this signal in the residuals of a three-planet fit to the RV data and the spectral activity indicators. From our stability analysis we derive a lower limit on the inclination of the system with the assumption of coplanar orbits which is imin = 0.9 deg. From the absence of a transit event with TESS, we derive an upper limit of the inclination of imax = 87.43 deg. Conclusions. YZ Ceti is a prime example of a system where strong aliasing hindered the determination of the orbital periods of exoplanets. Additionally, stellar activity influences the derivation of planetary parameters and modeling them correctly is important for the reliable estimation of the orbital parameters in this specific compact system. Stability considerations then allow additional constraints to be placed on the planetary parameters.

Determination of droop control coefficient of multi‐terminal VSC‐HVDC with system stability consideration

2018 ◽  
Vol 12 (13) ◽  
pp. 1508-1515 ◽  
Author(s):  
Qiao Peng ◽  
Tianqi Liu ◽  
Shunliang Wang ◽  
Yufeng Qiu ◽  
Xingyuan Li ◽  
...  
Keyword(s):  
System Stability ◽  
Droop Control ◽  
Control Coefficient ◽  
Stability Consideration
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