| 1. |
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| 2. |
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| 3. |
- Ahrentorp, Fredrik, et al.
(författare)
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Effective particle magnetic moment of multi-core particles
- 2015
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 380, s. 221-226
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Tidskriftsartikel (refereegranskat)abstract
- In this study we investigate the magnetic behavior of magnetic multi-core particles and the differences in the magnetic properties of multi-core and single-core nanoparticles and correlate the results with the nanostructure of the different particles as determined from transmission electron microscopy (TEM). We also investigate how the effective particle magnetic moment is coupled to the individual moments of the single-domain nanocrystals by using different measurement techniques: DC magnetometry, AC susceptometry, dynamic light scattering and TEM. We have studied two magnetic multi-core particle systems BNF Starch from Micromod with a median particle diameter of 100 am and FeraSpin R from nanoPET with a median particle diameter of 70 nm - and one single-core particle system - SHP25 from Ocean NanoTech with a median particle core diameter of 25 nm. (C) 2014 Elsevier B.V. All rights reserved.
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| 4. |
- Ahrentorp, Fredrik, et al.
(författare)
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Sensitive magnetic biodetection using magnetic multi-core nanoparticles and RCA coils
- 2017
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 427, s. 14-18
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Tidskriftsartikel (refereegranskat)abstract
- We use functionalized iron oxide magnetic multi-core particles of 100 nm in size (hydrodynamic particle diameter) and AC susceptometry (ACS) methods to measure the binding reactions between the magnetic nanoparticles (MNPs) and bio-analyte products produced from DNA segments using the rolling circle amplification (RCA) method. We use sensitive induction detection techniques in order to measure the ACS response. The DNA is amplified via RCA to generate RCA coils with a specific size that is dependent on the amplification time. After about 75 min of amplification we obtain an average RCA coil diameter of about 1 mu m. We determine a theoretical limit of detection (LOD) in the range of 11 attomole (corresponding to an analyte concentration of 55 fM for a sample volume of 200 mu L) from the ACS dynamic response after the MNPs have bound to the RCA coils and the measured ACS readout noise. We also discuss further possible improvements of the LOD.
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| 5. |
- Andersson Ersman, Peter, et al.
(författare)
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Integration of Screen Printed Piezoelectric Sensors for Force Impact Sensing in Smart Multifunctional Glass Applications
- 2022
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Ingår i: Advanced Engineering Materials. - : John Wiley & Sons, Ltd. - 1438-1656 .- 1527-2648. ; 24:11
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Tidskriftsartikel (refereegranskat)abstract
- Screen printed piezoelectric polyvinylidene fluoride?trifluoro ethylene (PVDF?TrFE)-based sensors laminated between glass panes in the temperature range 80?110?°C are presented. No degradation of the piezoelectric signals is observed for the sensors laminated at 110?°C, despite approaching the Curie temperature of the piezoelectric material. The piezoelectric sensors, here monitoring force impact in smart glass applications, are characterized by using a calibrated impact hammer system and standardized impact situations. Stand-alone piezoelectric sensors and piezoelectric sensors integrated on poly(methyl methacrylate) are also evaluated. The piezoelectric constants obtained from the measurements of the nonintegrated piezoelectric sensors are in good agreement with the literature. The piezoelectric sensor response is measured by using either physical electrical contacts between the piezoelectric sensors and the readout electronics, or wirelessly via both noncontact capacitive coupling and Bluetooth low-energy radio link. The developed sensor concept is finally demonstrated in smart window prototypes, in which integrated piezoelectric sensors are used to detect break-in attempts. Additionally, each prototype includes an electrochromic film to control the light transmittance of the window, a screen printed electrochromic display for status indications and wireless communication with an external server, and a holistic approach of hybrid printed electronic systems targeting smart multifunctional glass applications.
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| 6. |
- Blomgren, Jakob, et al.
(författare)
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Development of a sensitive induction-based magnetic nanoparticle biodetection method
- 2018
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Ingår i: Nanomaterials. - : MDPI AG. - 2079-4991. ; 8:11
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Tidskriftsartikel (refereegranskat)abstract
- We developed a novel biodetection method for influenza virus based on AC magnetic susceptibility measurement techniques (the DynoMag induction technique) together with functionalized multi-core magnetic nanoparticles. The sample consisting of an incubated mixture of magnetic nanoparticles and rolling circle amplified DNA coils is injected into a tube by a peristaltic pump. The sample is moved as a plug to the two well-balanced detection coils and the dynamic magnetic moment in each position is read over a range of excitation frequencies. The time for making a complete frequency sweep over the relaxation peak is about 5 minutes (10 Hz–10 kHz with 20 data points). The obtained standard deviation of the magnetic signal at the relaxation frequency (around 100 Hz) is equal to about 10−5 (volume susceptibility SI units), which is in the same range obtained with the DynoMag system. The limit of detection with this method is found to be in the range of 1 pM.
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| 7. |
- Carlsson, Raul, et al.
(författare)
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Connecting sensors inside smart castings
- 2018
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Konferensbidrag (refereegranskat)abstract
- The paper presents ongoing research on smart metal castings, meaning the technologicalinnovation of elevating cast metal components into metal components with integratedsensor functionality. Since the innovation targets aim straight at low cost industrial serialproduction, specific high cost and high-end solutions like inclusion of advancedelectronic equipment and after mounted sensors are not part of this innovationdevelopment. Integrating signal carriers inside metal castings to achieve metal castingswith sensor functionality requires robust solutions for connecting the sensor signal to thesensor interrogator and interpreter. The actual transmission of the signal may be donewirelessly or by wire. However, for several reasons there is a challenge with establishingan isolated and distinct connection between the sensor contact, and the contact at theexternal connection, regardless of whether it is to an antenna for wireless transmission orto a wire. This paper presents metallurgical challenges associated with choices ofmaterials, and combinations of metallurgical challenges and production process relatedchallenges, including the high melting temperatures. Aims are to find the rightcombinations of metal alloys, production simplicity, signal stability and robustness. Thepaper will present some of the tests made in the project so far. The project is run in aconsortium of the two Sweden-based industrial companies Husqvarna and SKF, and thetwo Swedish research institutes Swerea SWECAST and RISE Acreo.
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| 8. |
- Chakkarapani, Prabu, et al.
(författare)
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Encapsulation of methotrexate loaded magnetic microcapsules for magnetic drug targeting and controlled drug release
- 2015
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 380, s. 285-294
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Tidskriftsartikel (refereegranskat)abstract
- We report on the development and evaluation of methotrexate magnetic microcapsules (MMC) for targeted rheumatoid arthritis therapy. Methotrexate was loaded into CaCO3-PSS (poly (sodium 4-styrenesulfonate)) doped microparticles that were coated successively with poly (allylamine hydrochloride) and poly (sodium 4-styrenesulfonate) by layer-by-layer technique. Ferrofluid was incorporated between the polyelectrolyte layers. CaCO3-PSS core was etched by incubation with EDTA yielding spherical MMC. The MMC were evaluated for various physicochemical, pharmaceutical parameters and magnetic properties. Surface morphology, crystallinity, particle size, zeta potential, encapsulation efficiency, loading capacity, drug release pattern, release kinetics and AC susceptibility studies revealed spherical particles of ~3 µm size were obtained with a net zeta potential of +24.5 mV, 56% encapsulation and 18.6% drug loading capacity, 96% of cumulative drug release obeyed Hixson-Crowell model release kinetics. Drug excipient interaction, surface area, thermal and storage stability studies for the prepared MMC was also evaluated. The developed MMC offer a promising mode of targeted and sustained release drug delivery for rheumatoid arthritis therapy.
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| 9. |
- Gu, Yuanyu, et al.
(författare)
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Magnetic hyperthermia with ϵ-Fe2O3nanoparticles
- 2020
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Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 10:48, s. 28786-28797
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Tidskriftsartikel (refereegranskat)abstract
- Biocompatibility restrictions have limited the use of magnetic nanoparticles for magnetic hyperthermia therapy to iron oxides, namely magnetite (Fe3O4) and maghemite (γ-Fe2O3). However, there is yet another magnetic iron oxide phase that has not been considered so far, in spite of its unique magnetic properties: ϵ-Fe2O3. Indeed, whereas Fe3O4 and γ-Fe2O3 have a relatively low magnetic coercivity, ϵ-Fe2O3 exhibits a giant coercivity. In this report, the heating power of ϵ-Fe2O3 nanoparticles in comparison with γ-Fe2O3 nanoparticles of similar size (∼20 nm) was measured in a wide range of field frequencies and amplitudes, in uncoated and polymer-coated samples. It was found that ϵ-Fe2O3 nanoparticles primarily heat in the low-frequency regime (20-100 kHz) in media whose viscosity is similar to that of cell cytoplasm. In contrast, γ-Fe2O3 nanoparticles heat more effectively in the high frequency range (400-900 kHz). Cell culture experiments exhibited no toxicity in a wide range of nanoparticle concentrations and a high internalization rate. In conclusion, the performance of ϵ-Fe2O3 nanoparticles is slightly inferior to that of γ-Fe2O3 nanoparticles in human magnetic hyperthermia applications. However, these ϵ-Fe2O3 nanoparticles open the way for switchable magnetic heating owing to their distinct response to frequency.
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| 10. |
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| 11. |
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| 12. |
- Kumari, Monika, et al.
(författare)
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Experimental mixtures of superparamagnetic single domain magnetite with respect to Day-Dunlop plots
- 2015
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Ingår i: Geochemistry Geophysics Geosystems. - 1525-2027. ; 16:6, s. 1739-1752
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Tidskriftsartikel (refereegranskat)abstract
- Day‐Dunlop plots are widely used in paleomagnetic and environmental studies as a tool to determine the magnetic domain state of magnetite, i.e., superparamagnetic (SP), stable single‐domain (SD), pseudosingle‐domain (PSD), multidomain (MD), and their mixtures. The few experimental studies that have examined hysteresis properties of SD‐SP mixtures of magnetite found that the ratios of saturation remanent magnetization to saturation magnetization and the coercivity of remanence to coercivity are low, when compared to expected theoretical mixing trends based on Langevin theory. This study reexamines Day‐Dunlop plots using experimentally controlled mixtures of SD and SP magnetite grains. End‐members include magnetotactic bacteria (MSR‐1) as the SD source, and a commercial ferrofluid or magnetotactic bacteria (ΔA12) as the SP source. Each SP‐component was added incrementally to a SD sample. Experimental results from these mixing series show that the magnetization and coercivity ratios are lower than the theoretical prediction for bulk SP magnetic size. Although steric repulsion was present between the particles, we cannot rule out interaction in the ferrofluid for higher concentrations. The SP bacteria are noninteracting as the magnetite was enclosed by an organic bilipid membrane. Our results demonstrate that the magnetization and coercivity ratios of SD‐SP mixtures can lie in the PSD range, and that an unambiguous interpretation of particle size can only be made with information about the magnetic properties of the end‐members.
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| 13. |
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| 14. |
- Prabu, Chakkarapani, et al.
(författare)
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Layer-by-layer assembled magnetic prednisolone microcapsules (MPC) for controlled and targeted drug release at rheumatoid arthritic joints
- 2017
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 427, s. 258-267
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Tidskriftsartikel (refereegranskat)abstract
- We report here in about the formulation and evaluation of Magnetic Prednisolone Microcapsules (MPC) developed in order to improve the therapeutic efficacy relatively at a low dose than the conventional dosage formulations by means of magnetic drug targeting and thus enhancing bioavailability at the arthritic joints. Prednisolone was loaded to poly (sodium 4-styrenesulfonate) (PSS) doped calcium carbonate microspheres confirmed by the decrease in surface area from 97.48 m2/g to 12.05 of m2/g by BET analysis. Adsorption with oppositely charged polyelectrolytes incorporated with iron oxide nanoparticles was confirmed through zeta analysis. Removal of calcium carbonate core yielded MPC with particle size of ~3.48 µm, zeta potential of +29.7 mV was evaluated for its magnetic properties. Functional integrity of MPC was confirmed through FT-IR spectrum. Stability studies were performed at 25 °C±65% relative humidity for 60 days showed no considerable changes. Further the encapsulation efficiency of 63%, loading capacity of 18.2% and drug release of 88.3% for 36 h and its kinetics were also reported. The observed results justify the suitability of MPC for possible applications in the magnetic drug targeting for efficient therapy of rheumatoid arthritis.
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| 15. |
- Riordan, E, et al.
(författare)
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Design and implementation of a low temperature, inductance based high frequency alternating current susceptometer.
- 2019
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 90:7
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Tidskriftsartikel (refereegranskat)abstract
- We report on the implementation of an induction based, low temperature, high frequency ac susceptometer capable of measuring at frequencies up to 3.5 MHz and at temperatures between 2 K and 300 K. Careful balancing of the detection coils and calibration allow a sample magnetic moment resolution of 5 × 10−10 Am2 at 1 MHz. We discuss the design and characterization of the susceptometer and explain the calibration process. We also include some example measurements on the spin ice material CdEr2S4 and iron oxide based nanoparticles to illustrate functionality.
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| 16. |
- Rusu, Cristina, et al.
(författare)
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Miniaturized wireless water content and conductivity soil sensor system
- 2019
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Ingår i: Computers and Electronics in Agriculture. - : Elsevier B.V.. - 0168-1699 .- 1872-7107. ; 167
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Tidskriftsartikel (refereegranskat)abstract
- Obtaining more data for the research/studies of plants growing may be easier realized when suitable non-destructive detection methods are available. We are here presenting the development of a miniaturised, low-power, real-time, multi-parameter and cost-effective sensor for measurements in mini plugs (growth of seedling). The detection technique is based on measurement of electrical impedance at two frequencies for sensing two soil parameters, water content and water conductivity (dependent on e.g. total ions concentration). Electrical models were developed and comply with data at two frequencies. An easy and efficient calibration method for the sensor is established by using known liquids’ properties instead of various soil types. The measurements show a good correlation between the sensor's readings and the traditional soil testing. This soil sensor can easily send data wirelessly allowing for spot checks of substrate moisture levels throughout a greenhouse/field, and/or enable sensors to be buried inside the soil/substrate for long-term consecutive measurements.
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| 17. |
- Sette, Erik, 1984, et al.
(författare)
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Magnetic tracer-particle tracking in a fluid dynamically down-scaled bubbling fluidized bed
- 2015
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Ingår i: Fuel processing technology. - : Elsevier BV. - 0378-3820 .- 1873-7188. ; 138, s. 368-377
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Tidskriftsartikel (refereegranskat)abstract
- A method for 3-dimensional (3D) magnetic tracer particle tracking in a fluid dynamically downscaled fluidized bed is presented. The method applies anisotropic magnetoresistive (AMR) sensors to track a magnetic tracer particle in the form of an NdFeB-based permanent magnet. The fluid dynamically downscaled bed has a cross-section of 0.17 × 0.17 m2and is operated at ambient conditions with bronze powder as bulk solids and the tracer particle corresponding to a fuel particle. After up-scaling the bed corresponds to a 0.85 × 0.85 m2 bed of fuel ash or silica sand operated with air at 900 °C using anthracite coal as a fuel. Thus, the method provides continuous tracking of the tracer particle trajectorywhich, combined with the fluid dynamic scaling yields quantitativeinformation applicable to the study of fuel mixing in large-scale fluidized-bed processes operating under hot conditions. Application of the method represents a significant step forward compared to other experimental studies which are limited to qualitative interpretations; performed in 2D units and in cold 3D units which are not fluid dynamically scaled.It is shown that the AMR sensor system is able to work with the (non-magnetic) bronze powder resulting from the fluid dynamical downscaling, i.e. overcoming the limitation in signal penetration which prevents tracking of radioactive objects in such dense media. Thus, successful application of the AMR method for continuous 3D object tracking in a fluid dynamically downscaled unit is demonstrated for the first time. The measurement system provides both translational and rotational data, unleashing possibilities also as a validation tool of CFD models. The preliminary results show a spatial resolution on the order of 1 mm, while temporal resolution is on the order of milliseconds.
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| 18. |
- Sriviriyakul, Thana, et al.
(författare)
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Nanorheological studies of xanthan/water solutions using magnetic nanoparticles
- 2019
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier B.V.. - 0304-8853 .- 1873-4766. ; 473, s. 268-271
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Tidskriftsartikel (refereegranskat)abstract
- We show results of nanorheological studies of different concentrations of xanthan (non-Newtonian fluid) in water using magnetic nanoparticles (MNPs) together with the AC susceptibility (ACS) vs frequency method. For comparison we also show the ACS response for different concentrations of glycerol in water (Newtonian fluid). The ACS response is measured, and the data is modelled using dynamic magnetic models and different viscoelastic models. We study the ACS response (in-phase and out-of-phase ACS components) at different concentrations of xanthan in water (up to 1 wt% xanthan) and with a constant concentration of MNPs. We use MNP systems that show Brownian relaxation (sensitive to changes in the environmental properties around the MNPs). ACS measurements are performed using the DynoMag system. The Brownian relaxation of the MNP system peak is shifting down in frequency and the ACS response is broadening and decreases due to changes in the viscoelastic properties around the MNPs in the xanthan solution. The viscosity and the storage moduli are determined at each excitation frequency and compared with traditional macroscopic small amplitude oscillatory shear rheological measurements. The results from the traditional rheological and nanorheological measurements correlate well at higher xanthan concentration.
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| 19. |
- Staaf, Henrik, et al.
(författare)
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Simulated and measured piezoelectric energy harvesting of dynamic load in tires
- 2024
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Ingår i: Heliyon. - : Elsevier Ltd. - 2405-8440. ; 10:7
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Tidskriftsartikel (refereegranskat)abstract
- From 2007 in US and from 2022 in EU it is mandatory to use TPMS monitoring in new cars. Sensors mounted in tires require a continuous power supply, which currently only is from batteries. Piezoelectric energy harvesting is a promising technology to harvest energy from tire movement and deformation to prolong usage of batteries and even avoid them inside tires. This study presents a simpler method to simultaneous model the tire deformation and piezoelectric harvester performance by using a new simulation approach - dynamic bending zone. For this, angular and initial velocities were used for rolling motion, while angled polarization was introduced in the model for the piezoelectric material to generate correct voltage from tire deformation. We combined this numerical simulation in COMSOL Multiphysics with real-life measurements of electrical output of a piezoelectric energy harvester that was mounted onto a tire. This modelling approach allowed for 10 times decrease in simulation time as well as simpler investigation of systems parameters influencing the output power. By using experimental data, the simulation could be fine-tuned for material properties and for easier extrapolation of tire deformation with output harvested energy from simulations done at low velocity to the high velocity experimental data.
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| 20. |
- Zhou, Chunguang, et al.
(författare)
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Application of the magnetic tracer-tracking system in solids circulation measurement in a fluidized bed standpipe
- 2024
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Ingår i: Chemical Engineering Journal. - : Elsevier B.V.. - 1385-8947 .- 1873-3212. ; 498
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, the application of a magnetic tracer-tracking method in measuring solids circulation in a fluidized bed standpipe is investigated, due to its advantages of little intervention and cost efficiency, especially in pressurized systems. The method only needs to inject one small magnetic tracer to follow the main solid flow in the standpipe, therefore predicting particles’ real-time velocities. The measurement accuracy was thoroughly tested via comparing to conventional descending and accumulation methods. Main tracer properties, including tracer shape, density, and magnet core, were considered. Solids flow patterns in the standpipe were also regulated by changing orifice sizes and adding an inclined pipe, for the purpose of investigating the measurement accuracy in various conditions. The adverse effect of a narrow orifice on measurement was addressed via constructing a model that includes sand particles’ non-uniform velocity distribution across the standpipe cross-section. To interpret behaviors of tracers varied in size and density, a mathematical model was constructed to describe forces exerted on the tracer in the solids bed. The behaviors of the tracer immersed into the solids bed were also examined, providing an insight to that in a standpipe with continuous solids circulation. The solids bed density was also regulated by varying the mixture of olivine sand and carbonaceous particles at different proportions. The magnetic tracer-tracking method has been successfully validated, demonstrating good measurement accuracy of solids discharge flow rates in the standpipe, particularly avoiding cumbersome calibration. Moreover, the method can also determine sand waving and oscillated discharge behaviors, which might be related to solids’ stick–slip phenomena and is unlikely to be accurately determined using conventional descending and accumulation methods.
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| 21. |
- Zhou, Chunguang, 1986-, et al.
(författare)
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Application of the magnetic tracer-tracking system in solids circulation measurement in a fluidized bed standpipe
- 2024
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 498
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, the application of a magnetic tracer-tracking method in measuring solids circulation in a fluidized bed standpipe is investigated, due to its advantages of little intervention and cost efficiency, especially in pressurized systems. The method only needs to inject one small magnetic tracer to follow the main solid flow in the standpipe, therefore predicting particles' real-time velocities. The measurement accuracy was thoroughly tested via comparing to conventional descending and accumulation methods. Main tracer properties, including tracer shape, density, and magnet core, were considered. Solids flow patterns in the standpipe were also regulated by changing orifice sizes and adding an inclined pipe, for the purpose of investigating the measurement accuracy in various conditions. The adverse effect of a narrow orifice on measurement was addressed via constructing a model that includes sand particles' non-uniform velocity distribution across the standpipe crosssection. To interpret behaviors of tracers varied in size and density, a mathematical model was constructed to describe forces exerted on the tracer in the solids bed. The behaviors of the tracer immersed into the solids bed were also examined, providing an insight to that in a standpipe with continuous solids circulation. The solids bed density was also regulated by varying the mixture of olivine sand and carbonaceous particles at different proportions. The magnetic tracer-tracking method has been successfully validated, demonstrating good measurement accuracy of solids discharge flow rates in the standpipe, particularly avoiding cumbersome calibration. Moreover, the method can also determine sand waving and oscillated discharge behaviors, which might be related to solids' stick-slip phenomena and is unlikely to be accurately determined using conventional descending and accumulation methods.
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