Performance comparison of electrorheological valves with two different geometric configurations: Cylinder and plate

2008 ◽  
Vol 223 (3) ◽  
pp. 573-581 ◽  
Author(s):  
Y-M Han ◽  
K-G Sung ◽  
J W Sohn ◽  
S-B Choi
Keyword(s):  
Pressure Drop ◽  
Response Time ◽  
Analytical Model ◽  
Performance Comparison ◽  
Time Varying ◽  
Control Performance ◽  
Electrode Gap ◽  
Design Constraint ◽  
Geometric Configurations ◽  
Er Fluid

This article presents a control performance comparison of electrorheological (ER) fluid-based valves between cylindrical and plate configurations. After identifying Bingham characteristics of chemical starch-based ER fluid, an analytical model of each valve is established. In order to reasonably compare valve performance, design constraint is imposed by the choosing the same electrode gap and length, and each ER valve is manufactured. Valve performances such as pressure drop and response time are then evaluated and compared through analytical model and experiment. In addition, a time-varying pressure tracking controllability of each ER valve is experimentally realized.

The Fluid Power Control Performance Comparison Study of Two-Type ER Valve Based on FLUENT

2012 ◽  
Vol 472-475 ◽  
pp. 1989-1994
Author(s):  
Shi Sha Zhu ◽  
Liu Tao
Keyword(s):  
Pressure Drop ◽  
Power Control ◽  
Parallel Plate ◽  
Control Volume ◽  
Flow Simulation ◽  
Control Valve ◽  
Performance Comparison ◽  
Fluid Power ◽  
Control Performance ◽  
Plate Type

The current flow and pressure drop of ER valve which is a new type power control valve could be adjusted by the electric field signal directly .In this paper, the fluid power control performance of concentric cylindrical ER valve and parallel plate-type ER valve based on ER principal is comparative studied .First power control equation has been analysed, and then flow simulation of internal flow field of ER valve has been taken based on FLUENT software. The results show that with the increasing of the strength of excitation field, the flow through the two different type of ER valve decreases, the pressure drop between import and export is even greater; and the fluid power control performance of parallel plate-type ER valve is superior to concentric cylindrical ER valve under the same control volume.

Performance Comparison of Web Backend And Database: A Case Study Of Node.JS, Golang and MySQL, MongoDB

2019 ◽  
Vol 13 ◽  
Author(s):  
Faried Effendy ◽  
Taufik ◽  
Bramantyo Adhilaksono
Keyword(s):  
Response Time ◽  
Open Source ◽  
Poisson Distribution ◽  
Mobile Application ◽  
Web Applications ◽  
Performance Comparison ◽  
Memory Usage ◽  
Data Traffic ◽  
Cpu Utilization

: Substantial research has been conducted to compare web servers or to compare databases, but very limited research combines the two. Node.js and Golang (Go) are popular platforms for both web and mobile application back-ends, whereas MySQL and Go are among the best open source databases with different characters. Using MySQL and MongoDB as databases, this study aims to compare the performance of Go and Node.js as web applications back-end regarding response time, CPU utilization, and memory usage. To simulate the actual web server workload, the flow of data traffic on the server follows the Poisson distribution. The result shows that the combination of Go and MySQL is superior in CPU utilization and memory usage, while the Node.js and MySQL combination is superior in response time.

Numerical and Experimental Analysis of Turbulent Flow in Corrugated Pipes

2010 ◽  
Vol 132 (7) ◽  
Author(s):  
Henrique Stel ◽  
Rigoberto E. M. Morales ◽  
Admilson T. Franco ◽  
Silvio L. M. Junqueira ◽  
Raul H. Erthal ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Turbulent Flow ◽  
Friction Factor ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Velocity Magnitude ◽  
Geometric Configurations ◽  
Corrugated Surfaces ◽  
Friction Factors

This article describes a numerical and experimental investigation of turbulent flow in pipes with periodic “d-type” corrugations. Four geometric configurations of d-type corrugated surfaces with different groove heights and lengths are evaluated, and calculations for Reynolds numbers ranging from 5000 to 100,000 are performed. The numerical analysis is carried out using computational fluid dynamics, and two turbulence models are considered: the two-equation, low-Reynolds-number Chen–Kim k-ε turbulence model, for which several flow properties such as friction factor, Reynolds stress, and turbulence kinetic energy are computed, and the algebraic LVEL model, used only to compute the friction factors and a velocity magnitude profile for comparison. An experimental loop is designed to perform pressure-drop measurements of turbulent water flow in corrugated pipes for the different geometric configurations. Pressure-drop values are correlated with the friction factor to validate the numerical results. These show that, in general, the magnitudes of all the flow quantities analyzed increase near the corrugated wall and that this increase tends to be more significant for higher Reynolds numbers as well as for larger grooves. According to previous studies, these results may be related to enhanced momentum transfer between the groove and core flow as the Reynolds number and groove length increase. Numerical friction factors for both the Chen–Kim k-ε and LVEL turbulence models show good agreement with the experimental measurements.

Control of Vibration Using Compliant Actuators

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Sannia Mareta ◽  
Dunant Halim ◽  
Atanas A. Popov
Keyword(s):  
Vibration Control ◽  
Active Control ◽  
Passive Control ◽  
Performance Comparison ◽  
Control Performance ◽  
Frequency Bandwidth ◽  
Series Configuration ◽  
Compliant Actuators ◽  
Stiffness And Damping ◽  
Compliant Actuator

This work proposes a method for controlling vibration using compliant-based actuators. The compliant actuator combines a conventional actuator with elastic elements in a series configuration. The benefits of compliant actuators for vibration control applications, demonstrated in this work, are twofold: (i) vibration reduction over a wide frequency bandwidth by passive control means and (ii) improvement of vibration control performance when active control is applied using the compliant actuator. The vibration control performance is compared with the control performance achieved using the well-known vibration absorber and conventional rigid actuator systems. The performance comparison showed that the compliant actuator provided a better flexibility in achieving vibration control over a certain frequency bandwidth. The passive and active control characteristics of the compliant actuator are investigated, which shows that the control performance is highly dependent on the compliant stiffness parameter. The active control characteristics are analyzed by using the proportional-derivative (PD) control strategy which demonstrated the capability of effectively changing the respective effective stiffness and damping of the system. These attractive dual passive–active control characteristics are therefore advantageous for achieving an effective vibration control system, particularly for controlling the vibration over a specific wide frequency bandwidth.

scholarly journals Time-Varying Impedance Control of Port Hamiltonian System with a New Energy-Storing Tank

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Min Zheng ◽  
Tangqing Yuan ◽  
Tao Huang
Keyword(s):  
Control Method ◽  
Impedance Control ◽  
Conservative System ◽  
Time Varying ◽  
Control Performance ◽  
Singularity Problem ◽  
Numerical Examples ◽  
New Energy ◽  
Simulation Results ◽  
New Framework

In order to guarantee the passivity of a kind of conservative system, the port Hamiltonian framework combined with a new energy tank is proposed in this paper. A time-varying impedance controller is designed based on this new framework. The time-varying impedance control method is an extension of conventional impedance control and overcomes the singularity problem that existed in the traditional form of energy tank. The validity of the controller designed in this paper is shown by numerical examples. The simulation results show that the proposed controller can not only eliminate the singularity problem but can also improve the control performance.

scholarly journals Linkages and performance comparison among Eastern Europe stock markets

2014 ◽  
Author(s):  
José Soares Da Fonseca
Keyword(s):  
Stock Markets ◽  
Performance Comparison ◽  
Market Model ◽  
Var Model ◽  
Time Varying ◽  
Comparative Performance ◽  
Regional Market ◽  
Auto Regressive ◽  
And Performance ◽  
The Empirical Analysis

This article studies the linkages among the stock markets of Bulgaria, Czech Republic, Estonia, Hungary, Poland, Romania, Russia, Serbia, Slovenia and Ukraine. The empirical analysis begins with the estimation of a regional market model, whose beta parameters depend on predetermined information variables. Those parameters support the calculation of time‑varying Treynor ratios used on a comparative performance analysis. A Vector Auto Regressive Model (VAR) is used to estimate the performance causality within this group of markets. The VAR model results provide evidence that there is reciprocal performance across the majority of the selected stock markets.

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