scholarly journals Closed-Loop Recycling Dual-Mode Counter-Current Chromatography with Specified Sample Loading Durations: Modeling of Preparative and Industrial-Scale Separations

Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6561
Author(s):  
Artak E. Kostanyan ◽  
Andrey A. Voshkin
Keyword(s):  
Theoretical Analysis ◽  
Closed Loop ◽  
Current Mode ◽  
Operating Mode ◽  
Dual Mode ◽  
Sequential Separation ◽  
Mathcad Software ◽  
Counter Current ◽  
Further Development ◽  
Continuous Loading

We previously reported on a new counter-current chromatography (CCC) operating mode called closed-loop recycling dual-mode counter-current chromatography (CLR DM CCC), which incorporates the advantages of closed-loop recycling (CLR) and dual-mode (DM) counter-current chromatography and includes sequential separation of compounds in the closed-loop recycling mode with the mobile x-phase and in the inverted-phase counter-current mode with the mobile y-phase. The theoretical analysis of several implementations of this separation method was carried out under impulse sample injection conditions. This study is dedicated to the further development of CLR DM CCC theory applied to preparative and industrial separations, where high-throughput operation is required. Large sample volumes can be loaded via continuous loading within a specified time. To simulate CLR DM CCC separations with specified sample loading durations, equations are developed and presented in “Mathcad” software.

scholarly journals Current-Mode Third-Order Quadrature Oscillator Using CDTAs

2009 ◽  
Vol 2009 ◽  
pp. 1-5 ◽  
Author(s):  
Jiun-Wei Horng
Keyword(s):  
Theoretical Analysis ◽  
Phase Difference ◽  
Oscillation Frequency ◽  
Current Mode ◽  
Third Order ◽  
Quadrature Oscillator ◽  
Oscillation Condition ◽  
Transconductance Amplifiers ◽  
Simulation Results ◽  
A Current

This paper describes a current-mode third-order quadrature oscillator based on current differencing transconductance amplifiers (CDTAs). Outputs of two current-mode sinusoids with90°phase difference are available in the quadrature oscillator circuit. The oscillation condition and oscillation frequency are orthogonal controllable. The proposed circuit employs only grounded capacitors and is ideal for integration. Simulation results are included to confirm the theoretical analysis.

Multiple Inputs-Single Accumulated Output Mechanism for Soft Linear Actuators

2018 ◽  
Vol 11 (1) ◽  
Author(s):  
Kyeong Ho Cho ◽  
Ho Moon Kim ◽  
Youngeun Kim ◽  
Sang Yul Yang ◽  
Hyouk Ryeol Choi
Keyword(s):  
Artificial Muscle ◽  
Operating Mode ◽  
Robotic Arm ◽  
Soft Actuator ◽  
Wearable Robots ◽  
Working Principle ◽  
Linear Actuators ◽  
Soft Actuators ◽  
Muscle Actuators ◽  
Further Development

Soft linear actuators (SLAs) such as shape memory alloy (SMA) wires, pneumatic soft actuators, dielectric elastomer actuator, and twisted and coiled soft actuator (TCA) called artificial muscle actuators in general, have many advantages over the conventional actuators. SLAs can realize innovative robotic technologies like soft robots, wearable robots, and bionic arms in the future, but further development is still needed in real applications because most SLAs do not provide large displacement or force as needed. This paper presents a novel mechanism supplementing SLAs by accumulating the displacement of multiple SLAs. It adopts the principle of differential gears in reverse. Since the input units of the mechanism are extensible, more displacement can be accumulated by increasing the number of the input units as many as needed. The mechanism is basically used to accumulate displacements, but can be used to accumulate forces by changing its operating mode. This paper introduces the design and working principle of the mechanism and validates its operation experimentally. In addition, the mechanism is implemented on a robotic arm and its effectiveness is confirmed.

Macro-Micro Dual-Drive Stages Based on Dual Switching Condition and Local Closed Loop

2015 ◽  
Author(s):  
Jiwen Fang ◽  
Zhili Long ◽  
Lufan Zhang
Keyword(s):  
Steady State ◽  
Theoretical Analysis ◽  
Closed Loop ◽  
Voice Coil Motor ◽  
Switching Control ◽  
Positioning Error ◽  
Vibration Displacement ◽  
Pzt Actuator ◽  
Output Displacement ◽  
State Error

This paper presents macro-micro dual-drive stages using the hybrid actuators composed of voice coil motor (VCM) and piezoelectric actuator (PZT actuator). The macro stage driven by voice coil motor can achieve large travel range and coarse positioning. The micro stage with an embedded flexure hinges mechanism, actuated by the PZT actuator, can realize short range but high precision positioning. To gain precise performance, the dynamic modes of macro stage and micro stage are equivalent to mass-damping-spring system in this research. According to theoretical analysis, the output displacement of micro stage is proportional to the extension of the PZT Actuator. The linear relationship will be used to the motion control of micro stage. To realize perfect performance, the variable gain PID controller is designed to control the macro stage. In order to prevent saturation and damage of PZT actuator, dual switching control, positioning error threshold and small vibration displacement, are applied to the switching control. Beyond the micro stage range, the micro stage must be kept in its equilibrium position while the VCM instead reaches a long travel. The PZT actuator controller is used to compensate for position error after switching control. When the error is less than a set thres hold value, the error signal is added into the micro control loop. So the macro-micro dual-drive stages are working together to reduce the positioning error. The relationship between PZT actuator of closed loop and input voltage is linear by theoretical analysis and experiment test. So the micro stage uses an open servo loop structure, but the PZT actuator is controlled with PI controller in local closed loop in order to eliminate the nonlinear of PZT. The experimental system used in this study is single-axis dual-driving stages. Turbo PMAC PCI-Lite is the core of the whole system and executes PLC programs with motion programs. Experiments show that the steady state error of dual-drive stage is nano level. The steady state error of dual-drive stage can be improved. So dual-drive stages can increase the positioning accuracy of the whole system and the performance is superior to the single VCM stage.

scholarly journals A Current Mode Universal Filter and a Single Resistance Controlled Oscillator Employing only Grounded Passive Elements: Applications of VDCC

2021 ◽  
Vol 25 (2) ◽  
pp. 65-76
Author(s):  
Tajinder Singh Arora ◽  
Keyword(s):  
Integrated Circuit ◽  
Current Mode ◽  
Paper Analysis ◽  
Current Conveyor ◽  
Universal Filter ◽  
Dual Mode ◽  
Passive Element ◽  
Research Article ◽  
Sinusoidal Oscillator ◽  
A Current

This research article explores the possible applications of voltage differencing current conveyor (VDCC), as a current mode universal filter and a sinusoidal oscillator. Without the need for an additional active/passive element, a very simple hardware modification makes it a dual-mode quadrature oscillator from the filter configuration. Both the proposed circuit requires only two VDCC and all grounded passive elements, hence a preferable choice for integration. The filter has some desirable features such as availability of all five explicit outputs, independent tunability of filter parameters. Availability of explicit quadrature current outputs, independence in start and frequency of oscillations, makes it a better oscillator design. Apart from prevalent CMOS simulation results, VDCC is also realized and experimentally tested using the off-the-shelf integrated circuit. All the pen and paper analysis such as non-ideal, sensitivity and parasitic analysis supports the design.

Sign in / Sign up

Export Citation Format

Share Document