Closed-loop phase control of an 8×8 MEMS mirror array via in-situ interferometry

2012 ◽  
Author(s):  
Trevor Chan ◽  
Mischa Megens ◽  
Byung-Wook Yoo ◽  
Connie Chang-Hasnain ◽  
Ming Wu ◽  
...  
Keyword(s):  
Closed Loop ◽  
Phase Control

scholarly journals In situ measurement and closed-loop control for powder supply processes

2021 ◽  
Author(s):  
Philipp Peter Breese ◽  
Tobias Hauser ◽  
Daniel Regulin ◽  
Stefan Seebauer ◽  
Christian Rupprecht
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Closed Loop ◽  
In Situ Measurement ◽  
Closed Loop Control ◽  
Loop Control ◽  
Powder Feeder ◽  
Powder Mass

AbstractThe powder mass flow rate is one of the main parameters regarding the geometrical precision of built components in the additive manufacturing process of laser metal deposition. However, its accuracy, constancy, and repeatability over the course of the running process is not given. Reasons among others are the performance of the powder conveyors, the complex nature of the powder behavior, and the resulting issues with existing closed-loop control approaches. Additionally, a direct in situ measurement of the powder mass flow rate is only possible with intrusive methods. This publication introduces a novel approach to measure the current powder mass flow rate at a frequency of 125 Hz. The volumetric powder flow evaluation given by a simple optical sensor concept was transferred to a mass flow rate through mathematical dependencies. They were found experimentally for a nickel-based powder (Inconel 625) and are valid for a wide range of mass flow rates. With this, the dynamic behavior of a vibration powder feeder was investigated and a memory effect dependent on previous powder feeder speeds was discovered. Next, a closed-loop control with the received sensor signal was implemented. The concept as a whole gives a repeatable and accurate powder mass flow rate while being universally retrofittable and applicable. In a final step, the improved dynamic and steady performance of the powder mass flow rate with closed-loop control was validated. It showed a reduction of mean relative errors for step responses of up to 81% compared to the uncontrolled cases.

scholarly journals Mechanistic Studies on the Absorption-Enhancing Effects of Gemini Surfactant on the Intestinal Absorption of Poorly Absorbed Hydrophilic Drugs in Rats

Pharmaceutics ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 170 ◽  
Author(s):  
Tammam Alama ◽  
Kosuke Kusamori ◽  
Masaki Morishita ◽  
Hidemasa Katsumi ◽  
Toshiyasu Sakane ◽  
...  
Keyword(s):  
Intestinal Absorption ◽  
Gemini Surfactant ◽  
Closed Loop ◽  
Intestinal Cell ◽  
Mechanistic Studies ◽  
High Potency ◽  
Absorption Enhancers ◽  
Hydrophilic Drugs ◽  
Loop Method

Generally, the use of absorption enhancers might be the most effective approaches to ameliorate the enteric absorption of poorly absorbed substances. Among numerous absorption enhancers, we already reported that a gemini surfactant, sodium dilauramidoglutamide lysine (SLG-30) with two hydrophobic and two hydrophilic moieties, is a novel and promising adjuvant with a high potency in improving the absorption safely. Here, we examined and elucidated the absorption-improving mechanisms of SLG-30 in the enteric absorption of substances. SLG-30 increased the intestinal absorption of 5(6)-carboxyfluorescein (CF) to a greater level than the typical absorption enhancers, including sodium glycocholate and sodium laurate, as evaluated by an in situ closed-loop method. Furthermore, SLG-30 significantly lowered the fluorescence anisotropy of dansyl chloride (DNS-Cl), suggesting that it might increase the fluidity of protein sections in the intestinal cell membranes. Moreover, SLG-30 significantly lowered the transepithelial-electrical resistance (TEER) values of Caco-2 cells, suggesting that it might open the tight junctions (TJs) between the enteric epithelial cells. Additionally, the levels of claudin-1 and claudin-4 expression decreased in the presence of SLG-30. These outcomes propose that SLG-30 might improve the enteric transport of poorly absorbed substances through both transcellular and paracellular routes.

ON-LINE SUPPLY VOLTAGE SCALING BASED ON IN SITU DELAY MONITORING TO ADAPT FOR PVTA VARIATIONS

2012 ◽  
Vol 21 (08) ◽  
pp. 1240027 ◽  
Author(s):  
MARTIN WIRNSHOFER ◽  
NASIM POUR ARYAN ◽  
LEONHARD HEISS ◽  
DORIS SCHMITT-LANDSIEDEL ◽  
GEORG GEORGAKOS
Keyword(s):  
Closed Loop ◽  
Supply Voltage ◽  
Average Power ◽  
Voltage Scaling ◽  
Error Rates ◽  
Design Flow ◽  
Chain Model ◽  
Worst Case ◽  
On Line

The presented Pre-Error Adaptive Voltage Scaling (AVS) approach tunes the supply voltage of digital circuits dependent on the present Process, Voltage and Temperature variations as well as Aging (PVTA). By exploiting unused timing margin, produced by state-of-the-art worst-case designs, power consumption is minimized. Timing information of the circuit is obtained by in situ delay monitors (Pre-Error flip-flops), detecting late-arriving signals (pre-errors) in critical paths. Based on the occurrence of pre-errors, the voltage is adjusted by a low-overhead control unit connected to the on-chip voltage regulator. As the voltage is adapted during normal circuit operation (on-line), the randomness of the applied input pattern has to be considered. We developed a Markov chain model, based on transistor level simulations, to describe the resulting statistics of the closed-loop voltage control. With this model, the risk of overcritical voltage reductions and the effect of global and local variations on the closed-loop control can be analyzed. For an arithmetic circuit, synthesized in an industrial 65nm design-flow, an average power saving of 23% (including all overheads) is achieved for very low error rates below 1E-11.

scholarly journals Intelligent magnetic manipulation for gastrointestinal ultrasound

2019 ◽  
Vol 4 (31) ◽  
pp. eaav7725 ◽  
Author(s):  
Joseph C. Norton ◽  
Piotr R. Slawinski ◽  
Holly S. Lay ◽  
James W. Martin ◽  
Benjamin F. Cox ◽  
...  
Keyword(s):  
Closed Loop ◽  
Porcine Model ◽  
Diagnostic Endoscopy ◽  
Tissue Removal ◽  
Linear Probe ◽  
Tissue Surface ◽  
Gastrointestinal Ultrasound ◽  
Manual Manipulation

Diagnostic endoscopy in the gastrointestinal tract has remained largely unchanged for decades and is limited to the visualization of the tissue surface, the collection of biopsy samples for diagnoses, and minor interventions such as clipping or tissue removal. In this work, we present the autonomous servoing of a magnetic capsule robot for in situ, subsurface diagnostics of microanatomy. We investigated and showed the feasibility of closed-loop magnetic control using digitized microultrasound (μUS) feedback; this is crucial for obtaining robust imaging in an unknown and unconstrained environment. We demonstrated the functionality of an autonomous servoing algorithm that uses μUS feedback, both on benchtop trials and in vivo in a porcine model. We have validated this magnetic μUS servoing in instances of autonomous linear probe motion and were able to locate markers in an agar phantom with 1.0 ± 0.9 mm position accuracy using a fusion of robot localization and μUS image information. This work demonstrates the feasibility of closed-loop robotic μUS imaging in the bowel without the need for either a rigid physical link between the transducer and extracorporeal tools or complex manual manipulation.

Processing of PC/LCP in situ composites by closed-loop injection molding

2002 ◽  
Vol 62 (6) ◽  
pp. 757-765 ◽  
Author(s):  
Hong Shing Chan ◽  
Yang Leng ◽  
Furong Gao
Keyword(s):  
Injection Molding ◽  
Closed Loop ◽  
In Situ Composites

The Design of a Meter to Measure the Mass Flow-Specific Heat Product of a Heat Transfer Fluid

1986 ◽  
Vol 108 (2) ◽  
pp. 117-122 ◽  
Author(s):  
D. Proctor
Keyword(s):  
Heat Transfer ◽  
Specific Heat ◽  
Mass Flow ◽  
Closed Loop ◽  
Calibration Procedure ◽  
Loop System ◽  
Heat Transfer Fluid ◽  
Closed Loop System ◽  
Operating Range

This paper describes the design and calibration of a device for measuring the mass flow-specific heat (m˙Cp) product of a heat transfer fluid in situ in a closed loop system. Accuracy of the meter is ±0.07 percent to ±0.12 percent over its operating range of 18 to kW K−1, depending on the calibration procedure which has to be adopted.

Experimental Analysis for Wind Induced Disturbance Rejection on Bridge Crane Structures

2011 ◽  
Author(s):  
Julia Pasternack ◽  
Dan Thayer ◽  
Rohan Bansal ◽  
Ehsan Maleki ◽  
Greg Tao ◽  
...  
Keyword(s):  
Disturbance Rejection ◽  
Closed Loop ◽  
Operating Conditions ◽  
Bridge Crane ◽  
Specific System ◽  
Sensitivity Testing ◽  
System Parameters ◽  
Controller Performance ◽  
Multiple Variables

This paper describes the development of a feedback controller for rejecting wind disturbances on a crane payload. The goal of this research is to perform in-situ parameter sensitivity testing that is specific to a given crane structure. Through experimentation, this paper evaluates the robustness of a closed-loop controller that implements station keeping on a bridge crane. A set of general trends were developed to describe how altering system parameters and operating conditions affected controller performance. Such findings are not limited to single parameter characterization and can be extended to multiple variables given specific system specifications.

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