scholarly journals Optimal Control of Colloidal Trajectories in Inertial Microfluidics Using the Saffman Effect

Micromachines ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 592
Author(s):  
Felix Rühle ◽  
Christian Schaaf ◽  
Holger Stark
Keyword(s):  
Optimal Control ◽  
Colloidal Particles ◽  
Target Position ◽  
Channel Length ◽  
Channel Cross Section ◽  
Control Force ◽  
Channel Inlet ◽  
Channel Axis ◽  
Inertial Microfluidics ◽  
Constant Control

In inertial microfluidics colloidal particles in a Poiseuille flow experience the Segré-Silberberg lift force, which drives them to specific positions in the channel cross section. An external force applied along the microchannel induces a cross-streamline migration to a new equilibrium position because of the Saffman effect. We apply optimal control theory to design the time protocol of the axial control force in order to steer a single particle as precisely as possible from a channel inlet to an outlet at a chosen target position. We discuss the influence of particle radius and channel length and show that optimal steering is cheaper than using a constant control force. Using a single optimized control-force protocol, we demonstrate that even a pulse of particles spread along the channel axis can be steered to a target and that particles of different radii can be separarted most efficiently.

Elastic-Plastic Time History Analysis of MR Damping Structure Based on LQG Algorithm

2016 ◽  
Vol 858 ◽  
pp. 145-150
Author(s):  
Yu Liang Zhao ◽  
Zhao Dong Xu
Keyword(s):  
Optimal Control ◽  
Time History ◽  
Mr Damper ◽  
Time History Analysis ◽  
Control Force ◽  
Control Effect ◽  
Damping Force ◽  
Optimal Control Strategy ◽  
Elastic Plastic ◽  
History Analysis

This paper discussed an elastic-plastic time-history analysis on a structure with MR dampers based on member model, in which the elastoplastic member of the structure is assumed to be single component model and simulated by threefold line stiffness retrograde model. In order to obtain better control effect, Linear Quadratic Gaussian (LQG) control algorithm is used to calculate the optimal control force, and Hrovat boundary optimal control strategy is used to describe the adjustable damping force range of MR damper. The effectiveness of the MR damper based on LQG algorithm to control the response of the structure was investigated. The results from numerical simulations demonstrate that LQG algorithm can effectively improve the response of the structure against seismic excitations only with acceleration feedback.

scholarly journals On the optimal control force applied to tuned mass dampers for multi-degree-of-freedom systems

2004 ◽  
Vol 26 (1) ◽  
pp. 1-10
Author(s):  
Nguyen Dong Anh ◽  
Nguyen Chi Sang
Keyword(s):  
Optimal Control ◽  
Numerical Study ◽  
Degree Of Freedom ◽  
Control Force ◽  
Linear Quadratic ◽  
Tuned Mass Dampers ◽  
Coloured Noise ◽  
Optimal Theory ◽  
The One ◽  
Better Than

The design of active TMD for multi-degree-of-freedom systems subjected to second order coloured noise excitation is considered using the linear quadratic optimal theory. A detailed numerical study is carried out for a 2-DOF system. It is shown that the effectiveness of active TMD is better than the one of passive TMD.

Near-Optimal Time-Domain Control of Small Buoys in Irregular Waves

2014 ◽  
Author(s):  
Umesh A. Korde ◽  
R. Cengiz Ertekin
Keyword(s):  
Optimal Control ◽  
Impulse Response ◽  
Time Domain ◽  
The Body ◽  
Irregular Waves ◽  
Single Frequency ◽  
Impulse Response Functions ◽  
Control Force ◽  
Response Functions ◽  
Absorbed Power

Within the linear theory framework, smooth optimal control for maximum energy conversion in irregular waves requires independent synthesis of two non-causal impulse response functions operating on the body oscillations near the free surface, and one non-causal impulse response function relating the exciting force to the incident wave profile at the body. Full cancellation of reactive forces and matching of radiation damping thus requires knowledge or estimation of device velocity into the future. As suggested in the literature, the control force can be synthesized in long-crested waves by suitably combining the ‘full’ impulse response functions with wave surface elevation information at an appropriately determined distance up-wave of the device. This paper applies the near-optimal control approach investigated earlier by one of the authors (Korde, UA, Applied Ocean Research, to appear) to small floating cylindrical buoys. Absorbed power performance is compared with two other cases, (i) when single-frequency tuning is used based on non-real time adjustment of the reactive and resistive loads to maximize conversion at the spectral peak frequency, and (ii) when no control is applied with damping set to a constant value. Time domain absorbed power results are discussed.

scholarly journals Probability-Weighted Optimal Control for Nonlinear Stochastic Vibrating Systems with Random Time Delay

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
R. C. Hu ◽  
Q. F. Lü ◽  
X. F. Wang ◽  
Z. G. Ying ◽  
R. H. Huan
Keyword(s):  
Optimal Control ◽  
Time Delay ◽  
Stochastic Averaging ◽  
Stochastic Averaging Method ◽  
Random Time ◽  
Nonlinear Stochastic System ◽  
Control Force ◽  
Markov Jump ◽  
Optimal Control Strategy ◽  
Vibrating Systems

A probability-weighted optimal control strategy for nonlinear stochastic vibrating systems with random time delay is proposed. First, by modeling the random delay as a finite state Markov process, the optimal control problem is converted into the one of Markov jump systems with finite mode. Then, upon limiting averaging principle, the optimal control force is approximately expressed as probability-weighted summation of the control force associated with different modes of the system. Then, by using the stochastic averaging method and the dynamical programming principle, the control force for each mode can be readily obtained. To illustrate the effectiveness of the proposed control, the stochastic optimal control of a two degree-of-freedom nonlinear stochastic system with random time delay is worked out as an example.

Semi-Active Direct Velocity Control Method of Dynamic Response of Spatial Reticulated Structures Based on MR Dampers

2009 ◽  
Vol 12 (4) ◽  
pp. 547-558 ◽  
Author(s):  
Yan Bao ◽  
Cheng Huang ◽  
Dai Zhou ◽  
Yao-Jun Zhao
Keyword(s):  
Optimal Control ◽  
Control Strategy ◽  
Control Method ◽  
Optimal Placement ◽  
Feedback Gain ◽  
Control Force ◽  
Optimal Control Strategy ◽  
Integrated Method ◽  
Mr Dampers ◽  
Set Up

In this paper, a semi-active optimal control strategy for spatial reticulated structures (SRS) with MR dampers subjected to dynamic actions was proposed. The motion equation of SRS embedded with MR dampers was set up. The performance function of the optimal control strategy including both the structural responses and the control efforts was constituted for the optimization of feedback gain and MR damper placement in SRS, and an integrated method of genetic-gradient based algorithm was developed to solve this optimization problem. The clipped-optimal semi-active control strategy in the conjunction of velocity output feedback was applied to compute the desired control force from the MR dampers. Finally, a numerical example of SRS dealing with optimal placement of MR dampers and feedback gains of control system demonstrates the validity of the present semi-active optimal control strategy.

Instantaneous Stochastic Optimal Control of Seismically Excited Structures Based on Time Domain Explicit Method

2013 ◽  
Vol 790 ◽  
pp. 215-218
Author(s):  
Xue Ping Li ◽  
Chao Yu ◽  
Jie Yang Zhang ◽  
Jing Jie Zhou ◽  
Lin Ming Zhang
Keyword(s):  
Optimal Control ◽  
Time Domain ◽  
Stochastic Optimal Control ◽  
The State ◽  
Control Force ◽  
Building Structures ◽  
Explicit Method ◽  
Plane Shear ◽  
Shear Structure

A new instantaneous stochastic optimal control (ISO) for the linear building structures subjected to non-stationary random excitations is proposed. A plane shear structure is taken as the example to illustrate the proposed method. The main advantage of the method is that the control force is easy to be calculated because the expression of the control force is independent of the state of the system.

An active vibration control model for coupled flexible systems

2008 ◽  
Vol 222 (11) ◽  
pp. 2087-2098
Author(s):  
J C Niu ◽  
A Y T Leung ◽  
C W Lim ◽  
P Q Ge
Keyword(s):  
Optimal Control ◽  
Vibration Control ◽  
State Space ◽  
Power Flow ◽  
Passive Control ◽  
Flexible Structures ◽  
Coupled System ◽  
The State ◽  
Coupled Systems ◽  
Control Force

This paper presents a novel general model for complex flexible coupled systems. In this model, parallel structures of force actuators and passive spring isolators are installed between the machine and the foundation, and some moment actuators such as piezoelectric patches are installed on the flexible foundation whose vibration cancellation feature is the key object of vibration control. This model combines active and passive control, force and moment control into a single unit to achieve the efficient vibration control of flexible structures by multiple approaches. The state-space governing equations of the coupled system are deduced. Based on the description of the state-space equation of the coupled system, the transmission paths for the power flow transmitted into the foundation are discussed in the frequency domain, and then combined into a single function. The function includes two parts: the passive and active terms, which can be conveniently employed in an optimal control strategy to achieve power flow control. The transmission characteristics of the power flow by optimal control are discussed in detail. Numerical simulations are presented to show that both force and moment controls in the analytical model can achieve substantial vibration cancellation.

scholarly journals Momentum Transfer in Short-Channel Structures of Hexagonal Channel Cross-Section Shape: Experiments vs. CFD

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1036
Author(s):  
Katarzyna Sindera ◽  
Marzena Iwaniszyn ◽  
Przemysław Jodłowski
Keyword(s):  
Flow Resistance ◽  
Computational Models ◽  
Flow Characteristics ◽  
Channel Length ◽  
Channel Cross Section ◽  
Short Channel ◽  
Theoretical Approaches ◽  
Aisi 316 ◽  
Fluid Flow Characteristics ◽  
Channel Structures

Short-channel structures are promising catalyst carriers because it is easy to control the heat/mass transfer and fluid flow characteristics by changing their lengths. In this work, the flow resistance of hexagonal structures was investigated experimentally and numerically. The structure tested (6 mm long) was manufactured from AISI 316 steel using the selective laser melting technique. Due to some differences between theoretical approaches and practical results, two types of computational models were applied to analyze the pressure distribution in a short hexagonal duct. It was shown that although experimental results agree with some theoretical solutions, the channel wall thickness should not be omitted from the overall flow resistance. A comparison of short structures differing in channel length with widely used long monoliths was performed as well.

Robotic Arm Movement Optimization Using Soft Computing

2017 ◽  
Vol 6 (1) ◽  
pp. 1
Author(s):  
Surender Kumar ◽  
Kavita Rani ◽  
V. K. Banga
Keyword(s):  
Optimal Control ◽  
Genetic Algorithms ◽  
Soft Computing ◽  
Target Position ◽  
Arm Movement ◽  
Degree Of Freedom ◽  
Robotic Arm ◽  
Robot Arm ◽  
Soft Computing Techniques ◽  
Simulation Time

<p class="Text">Robots are commonly used in industries due to their versatility and efficiency. Most of them operating in that stage of the manufacturing process where the maximum of robot arm movement is utilized. Therefore, the robots arm movement optimization by using several techniques is a main focus for many researchers as well as manufacturer. The robot arm optimization is This paper proposes an approach to optimal control for movement and trajectory planning of a various degree of freedom in robot using soft computing techniques. Also evaluated and show comparative analysis of various degree of freedom in robotic arm to compensate the uncertainties like movement, friction and settling time in robotic arm movement. Before optimization, requires to understand the robot's arm movement i.e. its kinematics behavior. With the help of genetic algorithms and the model joints, the robotic arm movement is optimized. The results of robotic arm movement is optimal at all possible input values, reaches the target position within the simulation time.</p>

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