Inside Front Cover: Construction of Tissue‐Level Cancer‐Vascular Model with High‐Precision Position Control via In Situ 3D Cell Printing (Small Methods 7/2021)

For the precision rotor position control of stream selector, a control system based on direct current motor (DC motor) has been constructed. The DC motor, with a high-precision incremental encoder used as the driving force, was assembled with the stream selector rotor through a shaft coupling. Following the motor rotation, the encoder generated two-channel quadrature pulses and one channel index pulses. An ultralow-power consumption microcontroller (msp430f2232) received theses pulses and calculated them. The position of the slot was determined by the number of pulses counted from the index pulse. Operator can set and monitored the slot positions of five stream selectors simultaneously through the program which was written with LabVIEW on the host computer. This module featured high reliability and low power consumption compared with the one driven by step motor. Beyond that, it was much smaller and lighter.

Download Full-text

High-Precision Tracking Control of Machine Tool Feed Drives Based on ADRC

Volume 4A: Dynamics, Vibration, and Control ◽

10.1115/imece2016-66000 ◽

2016 ◽

Author(s):

Chengyong Zhang ◽

Yaolong Chen

Keyword(s):

Machine Tool ◽

High Precision ◽

Tracking Control ◽

Position Control ◽

Feedback System ◽

Pi Controller ◽

Ball Screw ◽

Feed Drives ◽

Precision Tracking ◽

Precision Tracking Control

In this paper, the active-disturbance-rejection control (ADRC) is applied to realize the high-precision tracking control of CNC machine tool feed drives. First, according to the number of the feedback channel, the feed systems are divided into two types: signal-feedback system, e.g., linear motor and rotary table, and double-feedback system, e.g., ball screw feed drive with a load/table position feedback. Then, the appropriate controller is designed to ensure the closed-loop control performance of each type of system based on the idea of ADRC. In these control frameworks, the extended state observers (ESO) estimate and compensate for unmodeled dynamics, parameter perturbations, variable cutting load, and other uncertainties. For the signal-feedback system, the modified ADRC with an acceleration feedforward term is used directly to regulate the load/table position response. However, for the double-feedback system, the ADRC is applied only to the motor position control, and a simple PI controller is used to achieve the accurate position control of the load. In addition, based on ADRC feedback linearization, a novel equivalent-error-model based feedforward controller is designed to further improve the command following performance of the double-feedback system. The experimental results demonstrate that the proposed controllers of both systems have better tracking performance and robustness against the external disturbance compared with the conventional P-PI controller.

Download Full-text

Ion track etching of polycarbonate membranes monitored by in situ small angle X-ray scattering

Physical Chemistry Chemical Physics ◽

10.1039/d1cp02063c ◽

2021 ◽

Author(s):

Alexander Kiy ◽

Christian Notthoff ◽

Shankar Dutt ◽

Mark Grigg ◽

Andrea Hadley ◽

...

Keyword(s):

High Precision ◽

Small Angle ◽

Selective Dissolution ◽

X Ray ◽

Ion Tracks ◽

X Ray Scattering ◽

Track Etching ◽

Polycarbonate Membranes ◽

Ray Scattering

In situ small angle X-ray scattering (SAXS) measurements of ion track etching of polycarbonate foils are used to directly monitor the selective dissolution of ion tracks with high precision, including...

Download Full-text

In-situ observations of the isotopic composition of methane at the Cabauw tall tower site

10.5194/acp-2016-60 ◽

2016 ◽

Cited By ~ 2

Author(s):

Thomas Röckmann ◽

Simon Eyer ◽

Carina van der Veen ◽

Maria E. Popa ◽

Béla Tuzson ◽

...

Keyword(s):

Isotopic Composition ◽

High Precision ◽

Temporal Resolution ◽

Isotope Ratio ◽

Mesoscale Model ◽

Ambient Air ◽

Model Calculations ◽

Dual Isotope ◽

Methane Budget

Abstract. High precision analyses of the isotopic composition of methane in ambient air can potentially be used to discriminate between different source categories. Due to the complexity of isotope ratio measurements, such analyses have generally been performed in the laboratory on air samples collected in the field. This poses a limitation on the temporal resolution at which the isotopic composition can be monitored with reasonable logistical effort. Here we present the performance of a dual isotope ratio mass spectrometric system (IRMS) and a quantum cascade laser absorption spectroscopy (QCLAS) based technique for in-situ analysis of the isotopic composition of methane under field conditions. Both systems were deployed at the Cabauw experimental site for atmospheric research (CESAR) in the Netherlands and performed in-situ, high-frequency (approx. hourly) measurements for a period of more than 5 months. The IRMS and QCLAS instruments were in excellent agreement with a slight systematic offset of +(0.05 ± 0.03) ‰ for δ13C and –(3.6 ± 0.4) ‰ for δD. This was corrected for, yielding a combined dataset with more than 2500 measurements of both δ13C and δD. The high precision and temporal resolution dataset does not only reveal the overwhelming contribution of isotopically depleted agricultural CH4 emissions from ruminants at the Cabauw site, but also allows the identification of specific events with elevated contributions from more enriched sources such as natural gas and landfills. The final dataset was compared to model calculations using the global model TM5 and the mesoscale model FLEXPART-COSMO. The results of both models agree better with the measurements when the TNO-MACC emission inventory is used in the models than when the EDGAR inventory is used. This suggests that high-resolution isotope measurements have the potential to further constrain the methane budget, when they are performed at multiple sites that are representative for the entire European domain.

Download Full-text