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Electrical Aspects
Published in Frank R. Spellman, The Science of Wind Power, 2022
There are three types or groups of magnets: Natural Magnets: found in the natural state in the form of a mineral (an iron compound) called magnetite.Permanent Magnets: (artificial magnet) hardened steel or some alloy such as Alnico bars that have been permanently magnetized. The permanent magnet most people are familiar with is the horseshoe magnet (see Figure 8.9). Wind turbines use permanent magnets made from rare-earth materials.Electromagnets: (artificial magnet) composed of soft-iron cores around which are wound coils of insulated wire. When an electric current flows through the coil, the core becomes magnetized. When the current ceases to flow, the core loses most of the magnetism.
Inspection Methods
Published in Mohamed Abdallah El-Reedy, Assessment, Evaluation, and Repair of Concrete, Steel, and Offshore Structures, 2018
Magnets come in a different shapes and the horseshoe (U) magnet is as shown in Figure 9.40 is one of the more common. The horseshoe magnet has north and south poles just like a bar magnet but the magnet is curved so the poles lie in the same plane. The magnetic lines of force flow from pole to pole just like in the bar magnet. However, since the poles are located closer together and a more direct path exists for the lines of flux to travel between the poles, the magnetic field is concentrated between the poles.
Polyethylene glycol-modified mesoporous zerovalent iron nanoparticle as potential catalyst for improved reductive degradation of Congo red from wastewater
Published in Journal of Environmental Science and Health, Part A, 2023
Ipsita Som, Mouni Roy, Rajnarayan Saha
Bare nZVI was synthesized by following a previously reported procedure, by one of our works[37] with some modification. Briefly, 0.73 g of anhydrous FeCl3 was dissolved in 100 mL 3:2 glycerol and water mixture taken in a 500 mL three neck round bottom flask. The FeCl3 solution was purged with nitrogen for several minutes to eliminate the dissolved oxygen present in reaction medium maintaining complete inert atmosphere. Then, 250 mL 0.25 (M) NaBH4 solution was added dropwise under nitrogen atmosphere, leading to the appearance of black-colored particles. After complete addition of NaBH4, the reaction mixture was stirred for 5 min at 500 rpm to ensure the completion of reaction. Then, the reaction mixture was transferred to a 500 mL conical flask to separate the obtained nanoparticles. Thenceforth, the obtained black colored particles were magnetically separated by using a horseshoe magnet. The synthesized nZVI particles were washed three times using double distilled water and finally absolute ethanol and vacuum dried at room temperature for overnight. After that, nZVI was stored in glass vials which are flushed with nitrogen gas prior to sustain inert atmosphere. The vials are kept in vacuum desiccator for further usage. The whole magnetic separation processes are represented in Figure A2. PEG-modified nZVI was synthesized by following the similar procedure mentioned above. Herein, 0.17 mL of PEG (Mw − 600) and 0.21 g of PEG (Mw – 6,000) were added individually after dissolving 0.73 g of anhydrous FeCl3 in 100 mL 3:2 glycerol and water mixture. The rest of the method is as similar as the synthesis of bare nZVI. PEG (Mw 600) and PEG (Mw 6,000) modified nZVI were denoted as nZVI-PEG600 and nZVI-PEG6000, respectively.