scholarly journals Impact of flow rate, water content, and capillary forces on in situ colloid mobilization during infiltration in unsaturated sediments

2008 ◽  
Vol 44 (6) ◽  
Author(s):  
Jianying Shang ◽  
Markus Flury ◽  
Gang Chen ◽  
Jie Zhuang
Keyword(s):  
Water Content ◽  
Flow Rate ◽  
Capillary Forces ◽  
Colloid Mobilization

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 Flow fields associated with in situ mineral leaching

1994 ◽  
Vol 36 (2) ◽  
pp. 133-151 ◽  
Author(s):  
Lawrence K. Forbes ◽  
Anthony M. Watts ◽  
Graeme A. Chandler
Keyword(s):  
Simple Model ◽  
Free Boundary ◽  
Numerical Method ◽  
Flow Rate ◽  
Recovery Rate ◽  
Flow Fields ◽  
Vertical Line ◽  
Rate Limiting ◽  
Mineral Leaching

AbstractA simple model for underground mineral leaching is considered, in which liquor is injected into the rock at one point and retrieved from the rock by being pumped out at another point. In its passage through the rock, the liquor dissolves some of the ore of interest, and this is therefore recovered in solution. When the injection and recovery points lie on a vertical line, the region of wetted rock forms an axi-symmetric plume, the surface of which is a free boundary. We present an accurate numerical method for the solution of the problem, and obtain estimates for the maximum possible recovery rate of the liquor, as a fraction of the injected flow rate. Limiting cases are discussed, and other geometries for fluid recovery are considered.

scholarly journals In situ measurement of micro flow rate using near infrared absorption method

2018 ◽  
Vol 26 (13) ◽  
pp. 17078 ◽  
Author(s):  
Seok Hwan Lee ◽  
Joohyun Lee ◽  
Sejong Chun ◽  
Woong Kang
Keyword(s):  
Flow Rate ◽  
Infrared Absorption ◽  
Near Infrared ◽  
In Situ Measurement ◽  
Absorption Method ◽  
Micro Flow

Optical Measurement Technique of Water Contents in Polymer Membrane for PEFCs

2005 ◽  
Vol 3 (1) ◽  
pp. 13-17 ◽  
Author(s):  
Kazuyoshi Fushinobu ◽  
Kenji Shimizu ◽  
Nariaki Miki ◽  
Ken Okazaki
Keyword(s):  
Water Content ◽  
Polymer Electrolyte ◽  
Optical Measurement ◽  
Polymer Electrolyte Membrane ◽  
Calibration Procedure ◽  
Polymer Electrolyte Fuel Cells ◽  
Infrared Light ◽  
Electrolyte Membrane ◽  
Transient Measurement

The feasibility of an optical technique is examined for the measurement of the membrane water content in polymer electrolyte fuel cells (PEFCs). Transmission of the infrared light of 1.92 μm wavelength is used to measure the water content in the polymer electrolyte membrane. A calibration procedure is examined, and the technique is applied for the transient measurement of a Nafion membrane that gives the value of water diffusion coefficient, consistent with previous reports. The technique is then applied to an operating PEFC to show its applicability for in situ measurement.

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