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 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 Removal of Cd(II) from Micro-Polluted Water by Magnetic Core-Shell Fe3O4@Prussian Blue

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2497
Author(s):  
Xinxin Long ◽  
Huanyu Chen ◽  
Tijun Huang ◽  
Yajing Zhang ◽  
Yifeng Lu ◽  
...  
Keyword(s):  
Prussian Blue ◽  
Co Adsorption ◽  
Magnetic Core ◽  
Diameter Distribution ◽  
Polluted Water ◽  
Core Shell ◽  
Freundlich Model ◽  
Rate Limiting Step ◽  
Rate Limiting

A novel core-shell magnetic Prussian blue-coated Fe3O4 composites (Fe3O4@PB) were designed and synthesized by in-situ replication and controlled etching of iron oxide (Fe3O4) to eliminate Cd (II) from micro-polluted water. The core-shell structure was confirmed by TEM, and the composites were characterized by XRD and FTIR. The pore diameter distribution from BET measurement revealed the micropore-dominated structure of Fe3O4@PB. The effects of adsorbents dosage, pH, and co-existing ions were investigated. Batch results revealed that the Cd (II) adsorption was very fast initially and reached equilibrium after 4 h. A pH of 6 was favorable for Cd (II) adsorption on Fe3O4@PB. The adsorption rate reached 98.78% at an initial Cd (II) concentration of 100 μg/L. The adsorption kinetics indicated that the pseudo-first-order and Elovich models could best describe the Cd (II) adsorption onto Fe3O4@PB, indicating that the sorption of Cd (II) ions on the binding sites of Fe3O4@PB was the main rate-limiting step of adsorption. The adsorption isotherm well fitted the Freundlich model with a maximum capacity of 9.25 mg·g−1 of Cd (II). The adsorption of Cd (II) on the Fe3O4@PB was affected by co-existing ions, including Cu (II), Ni (II), and Zn (II), due to the competitive effect of the co-adsorption of Cd (II) with other co-existing ions.

scholarly journals Uric Acid Is a Genuine Metabolite of Penicillium cyclopium and Stimulates the Expression of Alkaloid Biosynthesis in This Fungus

2002 ◽  
Vol 68 (4) ◽  
pp. 1524-1533 ◽  
Author(s):  
Florian Helbig ◽  
Jörg Steighardt ◽  
Werner Roos
Keyword(s):  
Uric Acid ◽  
Low Molecular Weight ◽  
Alkaloid Production ◽  
Alkaloid Biosynthesis ◽  
Penicillium Cyclopium ◽  
Measurable Activity ◽  
Reduced Rate ◽  
Rate Limiting

ABSTRACT On searching for endogenous, low-molecular-weight effectors of benzodiazepine alkaloid biosynthesis in Penicillium cyclopium uric acid was isolated from ethanolic or autoclaved mycelial extracts of this fungus. The isolation was based on a three-step high-pressure liquid chromatography procedure guided by a microplate bioassay, and uric acid was identified by mass spectrometry and the uricase reaction. Conidiospore suspensions that were treated with this compound during the early phase of outgrowth developed emerged cultures with an enhanced rate of alkaloid production. Uric acid treatment did not increase the in vitro measurable activity of the rate-limiting biosynthetic enzyme, cyclopeptine synthetase. However, these cultures displayed a reduced rate of uptake of the alkaloid precursor l-phenylalanine into the vacuoles of the hyphal cells as assayed in situ. It is suggested that the depressed capacity of vacuolar uptake caused by the contact of outgrowing spores with uric acid liberated from hyphal cells results in an enhanced availability of the precursor l-phenylalanine in the cytoplasm and thus accounts at least in part for the increase in alkaloid production.

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

scholarly journals Investigation of Speed Matching Affecting Contrarotating Fan’s Performance Using Wireless Sensor Network including Big Data and Numerical Simulation

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Hengxuan Luan ◽  
Liyuan Weng ◽  
Ranhui Liu ◽  
Yuanzhong Luan ◽  
Dongmin Li
Keyword(s):  
Big Data ◽  
Numerical Method ◽  
Flow Rate ◽  
Rate Condition ◽  
Small Flow Rate ◽  
Large Flow Rate ◽  
Small Flow ◽  
Power Capability ◽  
Two Stages ◽  
Large Flow

This paper describes the investigations performed to better understand two-stage rotor speed matching in a contrarotating fan. In addition, this study develops a comprehensive measuring and communication system for a contrarotating fan using ZigBee network. The investigation method is based on three-dimensional RANS simulations; the RANS equations are solved by the numerical method in conjunction with a SST turbulence model. A wireless measurement system using big data method is first designed, and then a comparison is done with experimental measurements to outline the capacity of the numerical method. The results show that when contrarotating fan worked under designed speed, performance of two-stages rotors could not be matched as the designed working condition was deviated. Rotor 1 had huge influences on flow rate characteristics of a contrarotating fan. Rotor 2 was influenced by flow rates significantly. Under large flow rate condition, the power capability of rotor 2 became very weak; under working small flow rate condition, overloading would take place to class II motor. In order to solve the performance mismatch between two stages of CRF under nondesigned working conditions, under small flow rate condition, the priority shall be given to increase of the speed of rotor 1, while the speed of rotor 2 shall be reduced appropriately; under large flow rate condition, the speed of rotor 1 shall be reduced and the speed of rotor 2 shall be increased at the same time.

Research and Application of Multi-Slug and Equi-Fluidity Oil Displacement Mechanism

2015 ◽  
Vol 733 ◽  
pp. 43-46
Author(s):  
Jiang Min Zhao ◽  
Tian Ge Li
Keyword(s):  
Pressure Gradient ◽  
Flow Rate ◽  
Oil Recovery ◽  
Recovery Rate ◽  
Actual Situation ◽  
Displacement Efficiency ◽  
Displacement Method ◽  
Oil Displacement ◽  
Oil Displacement Efficiency ◽  
Swept Volume

In this paper, several aspects of the improvement of the oil recovery were analyzed theoretically based on the mechanism that equi-fluidity enhances the pressure gradient. These aspects include the increase of the flow rate and the recovery rate, of the swept volume, and of the oil displacement efficiency. Also, based on the actual situation, the author designed the oil displacement method with gathered energy equi-fluidity, realizing the expectation of enhancing oil recovery with multi-slug and equi-fluidity oil displacement method.

GROWTH OF OXIDE LAYER ON GERMANIUM (011) SUBSTRATE UNDER DRY AND WET ATMOSPHERES

1999 ◽  
Vol 06 (06) ◽  
pp. 1053-1060 ◽  
Author(s):  
N. TABET ◽  
J. AL-SADAH ◽  
M. SALIM
Keyword(s):  
Simple Model ◽  
Oxide Film ◽  
Growth Kinetics ◽  
Photoelectron Spectroscopy ◽  
Early Stage ◽  
X Ray ◽  
Apparent Thickness ◽  
Different Temperatures ◽  
Kinetics Of

X-ray Photoelectron Spectroscopy (XPS) has been used to investigate the oxidation of (011) Ge substrates. The sample surfaces were CP4-etched, then annealed in situ, at different temperatures, for various durations. Dry and wet atmospheres were used. The oxidation rate during the early stage was increased by the presence of moisture in the atmosphere. A simple model was used to define and determine an apparent thickness of the oxide film from XPS measurements. The time dependence of the apparent thickness is consistent with a partial coverage of the surface by oxide islands. The growth kinetics of the oxide islands obeys a nearly cubic law.

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