Fundamental Study on Simple Quantitative Approach of Damping Performance for Variable Hydraulic Damper

2008 ◽  
Vol 56 ◽  
pp. 265-270
Author(s):  
Takeshi Hiwatashi ◽  
Hideo Fujitani
Keyword(s):  
Control Systems ◽  
Active Control ◽  
Passive Control ◽  
Control Method ◽  
Damping Factor ◽  
Fundamental Study ◽  
Equivalent Viscous Damping ◽  
Control Effectiveness ◽  
External Loads ◽  
Active Control Method

Recently, the semi-active control method has attracted significant attention from many researchers and engineers. This method aims to minimize a structure's response by changing the damper capacity according to the state of the structure and the external loads, and various kinds of semi-active control algorithms have been proposed. A lot of them utilize mathematically difficult algorithms that require complicated computer systems. With these methods, we can not evaluate the effectiveness and overall safety of the system under various kinds of loads. One reason is that the behaviors of structures incorporating such complicated control systems can not be evaluated by conventional means such as equivalent viscous damping factor based on hysteresis. Therefore, a semi-active control system is wished in which the control effects can be easily quantified as with passive control systems. This paper describes the result of having proposed the simple quantification approach for the semi-active control effectiveness.

scholarly journals A Critical Review of Supersonic Flow Control for High-Speed Applications

2021 ◽  
Vol 11 (15) ◽  
pp. 6899
Author(s):  
Abdul Aabid ◽  
Sher Afghan Khan ◽  
Muneer Baig
Keyword(s):  
Supersonic Flow ◽  
Flow Control ◽  
Active Control ◽  
Critical Review ◽  
High Speed ◽  
Passive Control ◽  
Control Method ◽  
Sudden Expansion ◽  
Control Approach ◽  
Cost Efficient

In high-speed fluid dynamics, base pressure controls find many engineering applications, such as in the automobile and defense industries. Several studies have been reported on flow control with sudden expansion duct. Passive control was found to be more beneficial in the last four decades and is used in devices such as cavities, ribs, aerospikes, etc., but these need additional control mechanics and objects to control the flow. Therefore, in the last two decades, the active control method has been used via a microjet controller at the base region of the suddenly expanded duct of the convergent–divergent (CD) nozzle to control the flow, which was found to be a cost-efficient and energy-saving method. Hence, in this paper, a systemic literature review is conducted to investigate the research gap by reviewing the exhaustive work on the active control of high-speed aerodynamic flows from the nozzle as the major focus. Additionally, a basic idea about the nozzle and its configuration is discussed, and the passive control method for the control of flow, jet and noise are represented in order to investigate the existing contributions in supersonic speed applications. A critical review of the last two decades considering the challenges and limitations in this field is expressed. As a contribution, some major and minor gaps are introduced, and we plot the research trends in this field. As a result, this review can serve as guidance and an opportunity for scholars who want to use an active control approach via microjets for supersonic flow problems.

High average power coherent femtosecond pulse combining system based on an all fiber active control method

2018 ◽  
Vol 15 (7) ◽  
pp. 075101 ◽  
Author(s):  
H L Yu ◽  
Z X Zhang ◽  
X L Wang ◽  
R T Su ◽  
H W Zhang ◽  
...  
Keyword(s):  
Active Control ◽  
Femtosecond Pulse ◽  
Control Method ◽  
Average Power ◽  
High Average Power ◽  
Active Control Method

Comparison of Times of Synchronization of Chaotic Burke-Shaw Attractor with Active Control and Integer and Optimum Fractional-Order Pecaro Carroll Method

2021 ◽  
Author(s):  
Ali Durdu ◽  
Yılmaz Uyaroğlu
Keyword(s):  
Active Control ◽  
Fractional Order ◽  
Chaotic Attractor ◽  
Secure Communication ◽  
Chaotic Systems ◽  
Control Method ◽  
Initial Conditions ◽  
Data Communication ◽  
Experimental Results ◽  
Active Control Method

Abstract Many studies have been introduced in the literature showing that two identical chaotic systems can be synchronized with different initial conditions. Secure data communication applications have also been made using synchronization methods. In the study, synchronization times of two popular synchronization methods are compared, which is an important issue for communication. Among the synchronization methods, active control, integer, and fractional-order Pecaro Carroll (P-C) method was used to synchronize the Burke-Shaw chaotic attractor. The experimental results showed that the P-C method with optimum fractional-order is synchronized in 2.35 times shorter time than the active control method. This shows that the P-C method using fractional-order creates less delay in synchronization and is more convenient to use in secure communication applications.

Investigating the dynamic characteristics of the hydrostatic bearing spindle system with active piezoelectric restrictors

2021 ◽  
pp. 1-20
Author(s):  
Yixin Zhang ◽  
Wei Pan ◽  
Shuo Zhan ◽  
Ran Huang ◽  
Shujiang Chen ◽  
...  
Keyword(s):  
Active Control ◽  
Dynamic Characteristics ◽  
Control Method ◽  
Spindle System ◽  
Optimization And Control ◽  
And Control ◽  
Pipeline Model ◽  
Structural Optimization And Control ◽  
Industrial Demand ◽  
Active Control Method

Abstract Studies show that active control technology can improve system performance and meet the increasing industrial demand in diverse applications. In the present study, the dynamic characteristics of the bearing-spindle system based on active piezoelectric (PZT) restrictors, including the amplitude-frequency and phase-frequency characteristics are analyzed theoretically and experimentally. In the analysis, the influence of the pipeline model on the system characteristics is studied. Then the feasibility and effectiveness of the active control method are verified through experiments. It is demonstrated that the theoretical and experimental results are consistent. The present study is expected to provide a guideline for further investigations on the structural optimization and control law design for active hydrostatic oil-film bearing spindle systems.

scholarly journals Review on vibration control in tall buildings: from the perspective of devices and applications

2020 ◽  
Author(s):  
BG Kavyashree ◽  
Shantharam Patil ◽  
Vidya S. Rao
Keyword(s):  
Control System ◽  
Active Control ◽  
Structural Control ◽  
Passive Control ◽  
Hybrid Control ◽  
Tall Buildings ◽  
Effective Control ◽  
Earthquake Load ◽  
History Of ◽  
External Loads

AbstractPermanent construction has evolved from the Palaeolithic age to today’s skyscrapers. Constructing the structure, which promises occupants safety, has become a concern because of the uncertainties in nature. Therefore in recent years, attention has been given to the development of structural protective devices that could take care of the external loads. Structural control against the wind and earthquake load has been seriously studied where the structure behaves differently for wind and earthquake load has been briefly discussed in this paper. Initially, paper discusses the history of the construction and the passive control system, which was used in structural control, is briefly discussed in this paper. Also, the implementation of active control has been discussed which was introduced later in the structural control for more effective control. But the limitations of the passive and active control system have introduced semi-active control and also the hybrid control strategy. The two mechanisms are put together in the semi-active and hybrid system to obtain all advantages of the algorithm along with overcoming their limitations. The review also briefs about stochastic vibrational control of the structure where randomness is considered in external loads, parameter of the system and also in the external devices which are implemented in the structural control. As construction sector is a complex system, big data analysis, a new field in structural control system is discussed and future scope is also mentioned.

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