Modeling of closed-loop recycling dual-mode counter-current chromatography based on non-ideal recycling model

2019 ◽  
Vol 1603 ◽  
pp. 240-250 ◽  
Author(s):  
Artak E. Kostanyan ◽  
Zhanetta N. Galieva
Keyword(s):  
Closed Loop ◽  
Dual Mode ◽  
Counter Current

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 Adaptive Notch Filter for Piezo-Actuated Nanopositioning System via Position and Online Estimate Dual-Mode

Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1525
Author(s):  
Chengsi Huang ◽  
Hongcheng Li
Keyword(s):  
Resonant Frequency ◽  
High Speed ◽  
Closed Loop ◽  
Notch Filter ◽  
Recursive Least Squares ◽  
Dual Mode ◽  
Fast Tracking ◽  
Adaptive Notch Filter ◽  
Loop Bandwidth ◽  
Mass Load

Due to the excellent advantages of high speed, high precision, and driving force, piezoelectric actuators nanopositioning systems have been widely used in various micro/nanomachining fields. However, the inherent resonance dynamic of the nanopositioning system generated by the flexure-hinge greatly deteriorates the positioning performance and limits the closed-loop bandwidth. Even worse, the notch filter for eliminating the effect of resonance does not work due to the varying resonant frequency resulting from the external disturbance or mass load. To this end, an adaptive notch filter for piezo-actuated nanopositioning system via position and online estimate dual-mode (POEDM) has been proposed in this paper, which can estimate the varying resonant frequency in real-time and suppress the resonance to improve the closed-loop bandwidth. First, a novel variable forgetting factor recursive least squares (VFF-RLS) algorithm for estimating resonant frequency online is presented, which is robust to the noise and provides the performances of both fast tracking and stability. Then, a POEDM method is proposed to achieve the online identification of the resonant frequency in the presence of noise and disturbance. Finally, a series of validation simulations are carried out, and the results indicate that, the frequency of input signal and the bandwidth have been achieved up to 12.5% and 87.5% of the first resonant frequency, respectively.

Isolation and Purification of Five Phloroglucinol Derivatives From Agrimonia Pilosa Ledeb by Counter-Current Chromatography Using Non-Aqueous Solvent Systems

2020 ◽  
Author(s):  
Lulu Fu ◽  
Chenghua Lu ◽  
Shengqiang Tong ◽  
Min Xu ◽  
Lan Tang ◽  
...  
Keyword(s):  
Closed Loop ◽  
Solvent System ◽  
The Other ◽  
Second Step ◽  
Two Phase ◽  
Isolation And Purification ◽  
Aqueous Solvent ◽  
Phloroglucinol Derivatives ◽  
Solvent Systems ◽  
Counter Current

Abstract Five non-polar phloroglucinol derivatives, viz. pseudo-aspidin, α-kosin and agripinol A-C were isolated and purified from Agrimonia pilosa Ledeb by semi-preparative counter-current chromatography. The separation was performed by a two-step elution with non-aqueous solvent systems. In the first step, an elution mode of a two-phase solvent system consisting of n-hexane-acetonitrile-dichloromethane-methanol (6:6:0.5:0.5, v/v/v/v) was used. We obtained sample Ι containing three components (47.0 mg) and sample ΙΙ containing two components (24.8 mg) from crude extract (371.0 mg). In the second step, sample Ι was successfully separated by closed-loop recycling mode with a solvent system consisting of n-hexane-acetonitrile-dichloromethane (10:7:3, v/v/v), yielding 17.8 mg of pseudo-aspidin, 18.5 mg of α-kosin and 6.4 mg of agripinol A. The other two compounds—8.7 mg of agripinol B and 13.6 mg of agripinol C—were obtained from sample ΙΙ in the same manner. All the isolated compounds had a high purity exceeding 95%.

A Dual-Mode Model Predictive Control Algorithm Trajectory Tracking in Discrete-Time Nonlinear Dynamic Systems

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Asad A. Ul Haq ◽  
Michael E. Cholette ◽  
Dragan Djurdjanovic
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
Discrete Time ◽  
Dynamic Systems ◽  
Trajectory Tracking ◽  
Closed Loop ◽  
Linear Control ◽  
Nonlinear Dynamic Systems ◽  
Closed Loop System ◽  
Dual Mode

In this paper, a dual-mode model predictive/linear control method is presented, which extends the concept of dual-mode model predictive control (MPC) to trajectory tracking control of nonlinear dynamic systems described by discrete-time state-space models. The dual-mode controller comprises of a time-varying linear control law, implemented when the states lie within a sufficiently small neighborhood of the reference trajectory, and a model predictive control strategy driving the system toward that neighborhood. The boundary of this neighborhood is characterized so as to ensure stability of the closed-loop system and terminate the optimization procedure in a finite number of iterations, without jeopardizing the stability of the closed-loop system. The developed controller is applied to the central air handling unit (AHU) of a two-zone variable air volume (VAV) heating, ventilation, and air conditioning (HVAC) system.

Multiple dual mode counter-current chromatography with variable duration of alternating phase elution steps

2014 ◽  
Vol 1347 ◽  
pp. 87-95 ◽  
Author(s):  
Artak E. Kostanyan ◽  
Andrey A. Erastov ◽  
Oleg N. Shishilov
Keyword(s):  
Dual Mode ◽  
Variable Duration ◽  
Counter Current
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