Pitting and galvanic corrosion of 2205 DSS with σ phase were investigated in the presence of Pseudomonas aeruginosa. Pitting corrosion was accelerated by σ phase, and further promoted by P. ...aeruginosa. The σ phase changed the distribution of pitting sites from being concentrated on phase boundaries and α phase in the solution treated coupons to being around σ phase in the biotic medium. The galvanic corrosion between α and γ phases was enhanced by the bacterium, and σ phase led to anodic dissolution of γ phase instead of α phase in DSS with solution treatment.
•Pitting corrosion of 2205 DSS is accelerated by σ phase.•Pitting corrosion is further promoted by P. aeruginosa.•Pitting occurs around σ phase due to the initial bacterial attachment.•The α phase corrodes galvanically for DSS with solution treatment.•The σ phase results in the anodic dissolution of γ phase instead of α phase.
Since its first demonstration more than a half century ago, magnetic levitation (MagLev) has gained eminent scientific attention from both the fundamental and applied points of view. In essence, ...MagLev shows highly nonlinear dynamics, described with nonlinear differential equations. Thus, in order to exploit the MagLev phenomenon, both mathematical models and control algorithms must be constructed. Frequently authors use simplifications of the model, and in doing so, limit the application of the MagLev model around a nominal operating point. In these simplified cases, the MagLev models may contain parameters that are not represented by proper physical quantities. Thus, in this work, we revised the issue of MagLev modelling from the first-principle approach. More specifically, we theoretically derived expressions for the interaction between the magnetic fields of the solenoid and a small magnetic object. The behaviour of the inductance on a distance from the solenoid was then described. The suggested MagLev modelling concept was verified experimentally, confirming the validity and correctness of the proposed MagLev mathematical model. The results presented here could thus be regarded as highly beneficial for formulating more complex MagLev designs exploitable in the field of model predictive control of the position of a levitating object.
•Magnetic levitation (MagLev) modelling is presented from first-principle approach.•MagLev force equation is derived and spatial behaviour of inductance is described.•MagLev mathematical model is constructed and successfully verified experimentally.•Results envisage reliable MagLev models for simulations, predictions and control.
•Efficient energy harvesting and vibration suppression by a bi-stable absorber is investigated.•Nonlinear magneto-electromechanical model is obtained via the Hamilton's principle.•Steady-state ...vibrations are effectively mitigated via strongly modulated response.•When vibration suppression and energy harvesting are of the same importance, the bistable absorber performance is 46.5% better than a linear absorber.•When energy harvesting has priority, the proposed absorber performance is 158 % higher than a linear absorber.
This paper investigates efficient simultaneous energy harvesting and vibration suppression utilizing a tunable bi-stable magneto-pieozelastic absorber (BMPA). The absorber comprises a bimorph cantilever beam exposed to a magnetic field. Furthermore, it is attached to a primary simply supported beam which is under an external excitation. The nonlinear magneto-electromechanical equations governing the coupled continuous system are derived utilizing the Hamilton's principle. First, the nonlinear magnetic force and its bifurcations are explored. Next, using numerical approaches, the efficacy of the absorber under a transient excitation from energy harnessing and vibration annihilation viewpoints is assessed. Furthermore, the efficiency of the BMPA in a steady-state harmonic excitation is investigated, both in time and frequency domains. Bifurcation diagrams disclosed that, based on magnets gap, the absorber performs periodic in-well low-amplitude oscillations, chaotic inter-well large-amplitude vibrations, or periodic high-amplitude motions. However, it is observed that in inter-well oscillations, chaotic strongly modulated response occurs and efficiency of the BMPA in vibration mitigation and energy harvesting markedly improves, compared to a linear absorber. Moreover, perfection rate examinations disclosed that when vibration suppression and energy harvesting are of the same importance, the bistable PZT absorber performance is 46.5% better than the corresponding linear absorber. Furthermore, when energy harvesting has priority, the BMPA performance is 158% higher than the linear absorber. Finally, harmonic balance method along with pseudo-arclength scheme are exploited to investigate the efficacy in large-amplitude inter-well scenario. It is illustrated that the system solutions are nonlinear and experience various cyclic fold and Hopf bifurcations. Further, the frequency response curves revealed that the BMPA decreases the host structure vibrations. Moreover, in this scenario, a considerable level of voltage is generated over a wide frequency range.
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Magnetic crystals formed by 2D layers interacting by weak van der Waals forces are currently a hot research topic. When these crystals are thinned to nanometric size, they can manifest strikingly ...different magnetic behavior compared to the bulk form. This can be the result of, for example, quantum electronic confinement effects, the presence of defects, or pinning of the crystallographic structure in metastable phases induced by the exfoliation process. In this work, an investigation of the magnetism of micromechanically cleaved CrCl3 flakes with thickness >10 nm is performed. These flakes are characterized by superconducting quantum interference device magnetometry, surface‐sensitive X‐ray magnetic circular dichroism, and spatially resolved magnetic force microscopy. The results highlight an enhancement of the CrCl3 antiferromagnetic interlayer interaction that appears to be independent of the flake size when the thickness is tens of nanometers. The estimated exchange field is 9 kOe, representing an increase of ≈900% compared to the one of the bulk crystals. This effect can be attributed to the pinning of the high‐temperature monoclinic structure, as recently suggested by polarized Raman spectroscopy investigations in thin (8–35 nm) CrCl3 flakes.
Low‐temperature magnetic force microscopy (MFM) and X‐ray magnetic circular dichroism are used to investigate micromechanically cleaved flakes of chromium trichloride crystals, revealing a ninefold increase of antiferromagnetic coupling between layers after exfoliation. Joint topographic and magnetic measurements by MFM on individual flakes show a common behavior in the 10–50 nm thickness range.
•A novel piezoelectric energy harvester driven by magnetic force is proposed.•A multi-step mechanism and a bistable structure are designed for the harvester.•The harvester has a wide working ...bandwidth and a stable high-voltage output.•The magnet array with staggered magnetic poles can increase the output voltage.
In this paper, a multi-step buckled beam piezoelectric energy harvester driven by magnetic force is proposed. To convert ambient mechanical vibration into electrical energy with increased operational frequency bandwidth and power density, the harvester utilizes a combination of multi-step mechanism and bistable structure. A multi-step mechanism in the form of a magnet array with staggered magnetic poles has been designed for the energy harvesting system to obtain a wide working bandwidth. A buckled beam as a bistable structure enables the harvester to demonstrate a high-voltage output. A theoretical model is developed to characterize the multi-step piezoelectric energy harvester. Both simulations and experiments on the fabricated experimental device are carried out to validate the design and analysis of the multi-step piezoelectric energy harvester. The experimental results indicate that output open circuit voltage of the harvester is 4.4V. The harvester generates a peak power of 5.0μW across resistive load of 3.3 MΩ at the frequency of 3.0Hz. The results show that the device can cause stable output voltage under wideband excitations. Furthermore, under the multi-step mechanism, the magnet array with staggered magnetic poles increases the output voltage of the harvester by 25.0% compared to the unidirectional magnetic pole arrangement.
The future of consumer electronics depends on the capability to reliably fabricate nanostructures with given physical properties. Therefore, techniques to characterize materials and devices with ...nanoscale resolution are crucial. Among these is magnetic force microscopy (MFM), which transduces the magnetic force between the sample and a magnetic oscillating probe into a phase shift, enabling the locally resolved study of magnetic field patterns down to 10 nm. Here, the progress done toward making quantitative MFM a common tool in nanocharacterization laboratories is shown. The reliability and ease of use of the calibration method based on a magnetic reference sample, with a calculable stray field, and a deconvolution algorithm is demonstrated. This is achieved by comparing two calibration approaches combined with numerical modeling as a quantitative link: measuring the probe's effect on the voltage signal when scanning above a nanosized graphene Hall sensor, and recording the MFM phase shift signal when the probe scans across magnetic fields produced by metallic microcoils. Furthermore, in the case of the deconvolution algorithm, it is shown how it can be applied using the open‐source software package Gwyddion. The estimated magnetic dipole approximation for the most common probes currently in the market is also reported.
Magnetic force microscopy, which allows mapping of the magnetic field distribution with nanoscale resolution, is a well‐known tool. However, for the last two decades, calibration was available only to a few labs. Now, after a few years of active research, the calibration protocols have been reviewed and improved, making it available to every laboratory.
Numerical simulation of hybrid nanomaterial free convection with helps of CVFEM was performed. Dispersing nanomaterial can minimize the exergy loss. The modeling outputs were depicted in terms of 3D ...plots and contours. Because of reduction of irreversibility with inclusion of nanoparticles, hybrid nanofluid was employed. Increasing Ha results in greater Xd and it is more sensible when convection become stronger. The growth of permeability increases nanomaterial motion and reduces the exergy drop.
•Heat transfer and exergy loss of nanomaterial has been examined.•CVFEM is applied to simulate current permeable geometry.•Exergy drop reduces with decline of Lorentz forces.•Augmenting Da and Ra make Bejan number to reduce.
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