scholarly journals Erratum: “Step Response Characteristics of Hydrostatic Journal Bearings With Self-Controlled Restrictors Employing a Floating Disk” (Journal of Tribology, 1999, 121, pp. 315–319)

1999 ◽  
Vol 121 (4) ◽  
pp. 677-677
Author(s):  
S. Yoshimoto ◽  
K. Kikuchi
Keyword(s):  
Journal Bearings ◽  
Step Response ◽  
Response Characteristics

Step Response Characteristics of Hydrostatic Journal Bearings With Self-Controlled Restrictors Employing a Floating Disk

1999 ◽  
Vol 121 (2) ◽  
pp. 315-320 ◽  
Author(s):  
S. Yoshimoto ◽  
K. Kikuchi
Keyword(s):  
Static Load ◽  
Journal Bearings ◽  
Step Response ◽  
Design Parameters ◽  
Static Stiffness ◽  
Load Direction ◽  
Response Characteristics ◽  
Theoretical Predictions ◽  
Theoretical Results ◽  
Very High

This paper describes the step response characteristics of hydrostatic journal bearings with self-controlled restrictors employing a floating disk. This type of bearing can achieve very high static stiffness by controlling the mass flow rate of the fluid entering the bearing clearance using a floating disk. Many design parameters such as supply pressure, viscosity, the magnitude of the step load and the imposed static load affect the step response characteristics of the proposed bearing. Therefore, the influences of each design parameter on the step response characteristics are theoretically investigated in this paper. Furthermore, the theoretical results are compared with the experimental results in order to verify the theoretical predictions. It is subsequently found that the proposed bearing consistently shows a stable step response irrespective of the step-load direction.

scholarly journals Advanced Performance Metrics and Sensitivity Analysis for Model Validation and Calibration

2020 ◽  
Author(s):  
Urmila Agrawal ◽  
Pavel Etingov ◽  
Renke Huang
Keyword(s):  
Sensitivity Analysis ◽  
Power Systems ◽  
Model Validation ◽  
Real World ◽  
Model Calibration ◽  
Dynamic Models ◽  
Performance Metrics ◽  
Step Response ◽  
Response Characteristics ◽  
Oscillatory Response

<pre>High quality generator dynamic models are critical to reliable and accurate power systems studies and planning. With the availability of PMU measurements, measurement-based approach for model validation has gained significant prominence. Currently, the model validation results are analyzed by visually comparing real--world PMU measurements with the model-based response measurements, and parameter adjustments rely mostly on engineering experience. This paper proposes advanced performance metrics to systematically quantify the generator dynamic model validation results by separately taking into consideration slow governor response and comparatively fast oscillatory response. The performance metric for governor response is based on the step response characteristics of a system and the metric for oscillatory response is based on the response of generator to each system mode calculated using modal analysis. The proposed metrics in this paper is aimed at providing critical information to help with the selection of parameters to be tuned for model calibration by performing enhanced sensitivity analysis, and also help with rule-based model calibration. Results obtained using both simulated and real-world measurements validate the effectiveness of the proposed performance metrics and sensitivity analysis for model validation and calibration.</pre>

Step Response Characteristics of Anisotropic Gel Actuator Hybridized with Nanosheet Liquid Crystal

2019 ◽  
Vol 31 (5) ◽  
pp. 647-656 ◽  
Author(s):  
Hitoshi Kino ◽  
◽  
Akihiro Kiyota ◽  
Takumi Inadomi ◽  
Tomonori Kato ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Steady State ◽  
Time Constant ◽  
Step Response ◽  
Response Property ◽  
First Order ◽  
Response Characteristics ◽  
Thermal Change ◽  
Heating And Cooling ◽  
Original Size

In this study, we focus on a soft anisotropic gel actuator hybridized with nanosheet liquid crystal. This gel actuator is highly hydrophilic and can be operated underwater. Gel actuators can contract when heated and expand back to their original size when cooled down. It is anisotropic in the contraction direction, aligned with the orientation of the nanosheet liquid crystal. However, details of this step response property against the actuator undergoing thermal change have not been clarified. In this paper, we introduce a method to measure the step response using a square test sheet with a side length of 2–10 mm and thickness of 0.1–1.0 mm. This measurement was used to measure the heating and cooling step response. The obtained result was approximated using a first-order lag system to determine a steady-state value and time constant. In addition, the characteristics of steady-state value and time constant were clarified from the viewpoint of shapes such as specific surface area and thickness.

scholarly journals Robust Digital Control for an LLC Current-Resonant DC-DC Converter

1970 ◽  
Vol 7 (1) ◽  
pp. 71-78
Author(s):  
Tomoya Nishimura ◽  
Yuto Adachi ◽  
Yoshihiro Ohta ◽  
Kohji Higuchi ◽  
Eiji Takegami ◽  
...  
Keyword(s):  
Output Voltage ◽  
Sudden Change ◽  
Experimental Studies ◽  
Load Resistance ◽  
Pulse Frequency ◽  
Step Response ◽  
Response Characteristics ◽  
Change Dynamics ◽  
Voltage Variation ◽  
Single Controller

If a pulse frequency and a load resistance of an LLC current-resonant DC-DC converter are changed, the dynamic characteristics are varied greatly, that is, the LLC current-resonant DC-DC converter has non-linear characteristics. In many applications of DC-DC converters, loads cannot be specified in advance, and they will be changed suddenly from no loads to full loads. A DC-DC converter system used a conventional single controller cannot be adapted to change dynamics and it occurs large output voltage variation. In this paper, a robust digital controllerfor suppress the change of step response characteristics and variation of output voltage in the load sudden change is proposed. Experimental studies using a micro-processor for the controller demonstrate that this type of digital controller is effective to suppress the variation.

Root Locus Diagrams and the Effect of Zeros on System Response

1997 ◽  
Vol 34 (1) ◽  
pp. 48-69 ◽  
Author(s):  
J. C. Peyton Jones ◽  
D. P. Atherton
Keyword(s):  
Step Response ◽  
System Response ◽  
Minimum Phase ◽  
Root Locus ◽  
Graphical Notation ◽  
Response Characteristics ◽  
Pole Dominance ◽  
Phase Systems ◽  
Insight Into

New expressions, and a graphical notation are introduced to quantify the effect of zeros on step response characteristics. The expressions, which also hold for non-minimum phase systems, are illustrated geometrically in the s-plane, and give a more accurate insight into a concept of pole dominance than the standard ‘pure-pole’ approximations.

scholarly journals CONTINUOUS FIREFLY ALGORITHM FOR OPTIMAL TUNING OF PID CONTROLLER IN AVR SYSTEM

2014 ◽  
Vol 65 (1) ◽  
pp. 44-49 ◽  
Author(s):  
Omar Bendjeghaba
Keyword(s):  
Pid Controller ◽  
Firefly Algorithm ◽  
Step Response ◽  
Voltage Regulator ◽  
Proportional Integral Derivative ◽  
Swarm Optimization ◽  
Response Characteristics ◽  
Tuning Method ◽  
Point Tracking ◽  
Avr System

Abstract This paper presents a tuning approach based on Continuous firefly algorithm (CFA) to obtain the proportional-integral- derivative (PID) controller parameters in Automatic Voltage Regulator system (AVR). In the tuning processes the CFA is iterated to reach the optimal or the near optimal of PID controller parameters when the main goal is to improve the AVR step response characteristics. Conducted simulations show the effectiveness and the efficiency of the proposed approach. Furthermore the proposed approach can improve the dynamic of the AVR system. Compared with particle swarm optimization (PSO), the new CFA tuning method has better control system performance in terms of time domain specifications and set-point tracking.

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