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The present communication revisits the almost century-and-a-half-old problem of some identical small magnets floating freely on the water's surface under the action of a superimposing magnetic field created by a stronger magnet placed above them. Originally introduced and performed by Alfred Marshall Mayer and reported in a series of articles starting from 1878 onward, the proposed experiments were intended to provide a model (theoretical and educational) for the building block of matter that, at a microscopic level, is the atom. The self-organizing patterns formed by the repelling small magnets under the influence of a single attractive central force are presented in a slightly different reenactment of the original experiments. Although the set-up is characterized by an axially symmetric magnetostatic structure, and the floated magnets are all identical, the resulting equilibrium patterns are not necessarily symmetrical, as one would expect. To the authors' best knowledge, the present communication proposes for the first time a quantitative approach to that extremely complex conceptual problem by providing a methodology for computing the equilibrium point coordinates in the case of n = 1...20 floating magnets, as proposed by the original A.M. Mayer experiments. A good agreement between the experiments and computed data was demonstrated for n = 2...15 (1st variant), but it was less accurate while still preserving the experimental set-up configurations for n = 15 (2nd variant)...20. Finally, this study draws the conclusions from the performed experiments and their corresponding computer simulations, identifies some open issues, and outlines possible solutions to address them, as well as future developments concerning the subject in general. [ABSTRACT FROM AUTHOR]

The present paper proposes an analytical magnetic charges equivalence procedure for computing the magnetic field created by the lifting magnets in a non-vertical levitation structure. The proposed method avoids the repetitive solving of the problem needed by any numerical analyse package in order to reach the balance of forces at the equilibrium point. Demagnetization in open-loop of the used NdFeB magnets is taken into account by determining their operating point on the BH-curve. The equilibrium point location is calculated and its stability is checked through the stability discriminants. Several horizontal and an inclined structures are computed and the results are compared with the ones obtained with the professional field computation package RADIA. Finally, the calculation results are validated in comparison with experimental results. [ABSTRACT FROM AUTHOR]

The problem of energy consumption reduction establishes important challenges for electric motor producers in the framework of new international regulations regarding the conditions that must be accomplished by motors in the near future. One of the most important topics is related to the core loss decrease directly linked to the effect of electrical steel degradation induced by the cutting technology. Understanding exactly how this phenomenon occurs by analyzing the chemical, mechanical, crystallographic, magnetic domain, and magnetic properties is of utmost importance when manufacturing processes must be changed and adapted to a new market characterized by high-efficiency motors. Today, mechanical and laser cutting technologies are the most used because of their reduced price and high-speed process. Still, unfortunately, these methods are not the best due to the fact that they lead, in most cases, to a high value of magnetic core losses, low electromagnetic torque, and hence reduced efficiency. This review paper shows that non-conventional technologies such as water jetting and electroerosion could be applied if proper modifications are added. This paper's main idea is to present a comprehensive study regarding the impact of cutting technologies on microhardness and residual stresses, crystallographic texture, magnetic domain structure, and magnetic properties of some non-oriented electrical steels used in motor production. It provides a detailed analysis of the abovementioned aspects by including the authors' research and findings in the wider context of other research group contributions. It also offers a general idea of the mechanisms present at the macro- and microscopic levels. The readers can find some of the most used analytical models, including the cutting process's damaged effect on the magnetic properties' variation based on a simple mathematical approach and examples of finite element modeling performed on real motor designs implemented in various programs. Last but not least, some practical implementations of the cutting procedure's influence on motor working conditions are presented in the last section of the paper. It provides an up-to-date analysis regarding how the cutting method should be included in high-efficiency motor production by emphasizing the importance of the topic and identifying where supplementary research must be undertaken. From the investigated literature, by analyzing specific sample geometries associated with different characterization methods, it can be concluded that all the cutting technologies have an important contribution to the mechanical and magnetic quantities. When the magnetic core of an electric motor is produced through non-conventional methods, the overall influence of the cutting procedure has a low percentage in the motor efficiency, as presented in this paper. [ABSTRACT FROM AUTHOR]

Treatment of bone defects resulting after tumor surgeries, accidents, or non-unions is an actual problem linked to morbidity and the necessity of a second surgery and often requires a critical healthcare cost. Although the surgical technique has changed in a modern way, the treatment outcome is still influenced by patient age, localization of the bone defect, associated comorbidities, the surgeon approach, and systemic disorders. Three-dimensional magnesium-based scaffolds are considered an important step because they can have precise bone defect geometry, high porosity grade, anatomical pore shape, and mechanical properties close to the human bone. In addition, magnesium has been proven in in vitro and in vivo studies to influence bone regeneration and new blood vessel formation positively. In this review paper, we describe the magnesium alloy's effect on bone regenerative processes, starting with a short description of magnesium's role in the bone healing process, host immune response modulation, and finishing with the primary biological mechanism of magnesium ions in angiogenesis and osteogenesis by presenting a detailed analysis based on a literature review. A strategy that must be followed when a patient-adapted scaffold dedicated to bone tissue engineering is proposed and the main fabrication technologies are combined, in some cases with artificial intelligence for Mg alloy scaffolds, are presented with examples. We emphasized the microstructure, mechanical properties, corrosion behavior, and biocompatibility of each study and made a basis for the researchers who want to start to apply the regenerative potential of magnesium-based scaffolds in clinical practice. Challenges, future directions, and special potential clinical applications such as osteosarcoma and persistent infection treatment are present at the end of our review paper. [ABSTRACT FROM AUTHOR]

The performances of non-oriented iron-silicon (NO Fe-Si) alloys, which are among the most commonly used materials for soft magnet applications, suffer because of mechanical stresses, whose intensity depends on the cutting technology applied, when these materials are used in the shape of strips in the magnetic core manufacture. This paper presents a detailed analysis of the influence that the stresses, arising from mechanical punching technology, have on the energy losses and normal magnetization curves, measured on NO Fe-Si samples. High-quality Cogent NO20 Hi-Lite and M300-35A samples, having a thickness of 0.2 and 0.35 mm, respectively, with a length of 300 mm, were cut by guillotine shear method to obtain strips with widths varying from 5 to 60 mm. The attained strips having different widths were characterized using a hysteresisgraph-wattmeter to measure ac energy losses and hysteresis cycles in the frequency range from 3 to 1500 Hz for NO20 and up to 400 Hz in the case of M300-35A. The dynamic loss behavior is presented in accordance with the statistical theory of losses, while a low to moderate increase is observed with the sample width decrease. The measured total energy losses were then decomposed into the hysteresis and dynamic components, including the classical and excess energy losses. The energy losses’ behavior as a function of the strip width was, eventually, analyzed and modeled, considering that cutting process induces local hardening on the borders of the samples. The experimental results put also in evidence a hyperbolic variation of the hysteresis losses versus strip width in both cases. As a remarkable result of these considerations, we observe that the evolution of the hysteresis energy losses can be predicted from the very wide, almost undamaged, to narrowest, fully degraded width strips. [ABSTRACT FROM AUTHOR]

Bone defects characterized by limited regenerative properties are considered a priority in surgical practice, as they are associated with reduced quality of life and high costs. In bone tissue engineering, different types of scaffolds are used. These implants represent structures with well-established properties that play an important role as delivery vectors or cellular systems for cells, growth factors, bioactive molecules, chemical compounds, and drugs. The scaffold must provide a microenvironment with increased regenerative potential at the damage site. Magnetic nanoparticles are linked to an intrinsic magnetic field, and when they are incorporated into biomimetic scaffold structures, they can sustain osteoconduction, osteoinduction, and angiogenesis. Some studies have shown that combining ferromagnetic or superparamagnetic nanoparticles and external stimuli such as an electromagnetic field or laser light can enhance osteogenesis and angiogenesis and even lead to cancer cell death. These therapies are based on in vitro and in vivo studies and could be included in clinical trials for large bone defect regeneration and cancer treatments in the near future. We highlight the scaffolds' main attributes and focus on natural and synthetic polymeric biomaterials combined with magnetic nanoparticles and their production methods. Then, we underline the structural and morphological aspects of the magnetic scaffolds and their mechanical, thermal, and magnetic properties. Great attention is devoted to the magnetic field effects on bone cells, biocompatibility, and osteogenic impact of the polymeric scaffolds reinforced with magnetic nanoparticles. We explain the biological processes activated due to magnetic particles' presence and underline their possible toxic effects. We present some studies regarding animal tests and potential clinical applications of magnetic polymeric scaffolds. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) is an important technology that led to a high evolution in the manufacture of personalized implants adapted to the anatomical requirements of patients. Due to a worldwide graft shortage, synthetic scaffolds must be developed. Regarding this aspect, biodegradable materials such as magnesium and its alloys are a possible solution because the second surgery for implant removal is eliminated. Magnesium (Mg) exhibits mechanical properties, which are similar to human bone, biodegradability in human fluids, high biocompatibility, and increased ability to stimulate new bone formation. A current research trend consists of Mg-based scaffold design and manufacture using AM technologies. This review presents the importance of biodegradable implants in treating bone defects, the most used AM methods to produce Mg scaffolds based on powder metallurgy, AM-manufactured implants properties, and in vitro and in vivo analysis. Scaffold properties such as biodegradation, densification, mechanical properties, microstructure, and biocompatibility are presented with examples extracted from the recent literature. The challenges for AM-produced Mg implants by taking into account the available literature are also discussed. [ABSTRACT FROM AUTHOR]

Grain-oriented silicon iron alloys present an important magnetocrystalline anisotropy, which has a strong influence on the normal magnetization curve and the energy losses. The theory of Orientation Distribution Functions (ODF), applied in the case of materials presenting crystalline symmetry of body centered cubic structure and orthorhombic strip symmetry, is taken into consideration. The magnetocrystalline anisotropy is analyzed on JFE Steel Corp. commercial grade M-0H grain-oriented electrical steel, cut at different angles with respect to the rolling direction, ranging from 0° to 90° in equal steps of 15°. The accuracy of the ODF method is analyzed by taking into account firstly three sets of experimental data, obtained for 0°, 45°, and 90°, then four sets, in the case of 0°, 30°, 60°, and 90° cut samples, and in the last case for all seven directions. The magnetic properties are predicted for any arbitrary direction and a relative error is analyzed, in each case, between the experimental and the numerical data. Finally, a proper number of experimental measurements was chosen, by considering a compromise between the magnitude of the error and the amount of experimental data. The samples were cut through mechanical punching, laser and travelling wire electro-erosion technologies. The normal magnetization curves and the energy losses were measured utilizing an industrial single strip tester (SST), at the frequency of 50 Hz. The model presented in the paper is a useful tool in the electric transformer cores' design since every magnetic property could be predicted with an increased accuracy in the case of each angle. [ABSTRACT FROM AUTHOR]

• Simple phenomenological model regarding the dependence of energy losses on the strip width. • Simple phenomenological model regarding the dependence of magnetization curve on the strip width. • Energy loss separation. • Estimation of cutting damaged width strip. We investigate the effect of mechanical cutting on the magnetic properties of high permeability grain-oriented (HGO) laser-scribed Fe-Si sheets. Measurements have been performed on strips of different widths (5 to 60 mm) cut from 0.27 mm thick sheets. Normal magnetization curve and energy loss have been determined by means of a digitally controlled single strip tester from 1 Hz to 1 kHz at peak magnetic polarization values J p = 1000 mT and 1700 mT. The results fit into a simple phenomenological model regarding the dependence of magnetization curve and energy loss on the strip width, in substantial continuity with the approach originally developed for non-oriented electrical steels. The hysteresis W h and excess W exc loss components are shown to depend on the strip width according to a hyperbolic law, with a limiting fully hardened strip predicted to occur for widths around 3.5 mm. It is then consistently observed that the mechanical cutting of standard 30 mm wide HGO Epstein strips is conducive to an increase of the energy loss at 50 Hz and 1.7 T of the order of 13 %. [ABSTRACT FROM AUTHOR]

• Non-oriented steels cut through guillotine and water-jet technologies. • Strain-hardened band width estimation using hyperbolic dependence based on magnetization curves. • Analysis of losses by identifying their components in strain-hardened zones. • Phenomenological formulation for hysteresis and excess loss dependence on strip width. • General and simple model to be applied for different cut profiles and technologies. Magnetization curve and energy losses have been analyzed in non-oriented (NO) Fe-Si alloys with variable thickness (0.20 mm–0.35 mm), cut at widths ranging between 5 mm and 60 mm, in order to assess the impact of cutting, either done by punching or water-jet techniques. Measurements were performed by means of a digitally controlled single strip tester, from dc up to 1.5 kHz, at peak polarization values J p = 1.0 T and 1.5 T. The evolution of the magnetization curve and the structure-dependent hysteresis W h and excess W exc loss components have been assessed as a function of the strip width using a simple phenomenological model, by which the extension of the damaged area at the edges of the cut sheets is estimated. Such a model assumes a hyperbolic dependence of the measured polarization on the cut strip width. The limiting values of W h and W exc for the fully damaged and the pristine sheets are in this way estimated, showing that one can simply and affordably predict the magnetic behavior of NO Fe-Si steels subjected to cutting. [ABSTRACT FROM AUTHOR]

Due to worldwide regulations on electric motor manufacturing, the energy efficiency of these devices has to be constantly improved. A solution may reside in the fact that high quality materials and adequate cutting technologies should be carefully chosen. The magnetic properties of non-oriented electrical steels are affected by the cutting methods, through induced plastic, and thermal stresses. There is also an important correlation between chemical composition and different magnetic properties. In this paper, we analyze different industrial grades of non-oriented electrical steels, used in electrical machines' core manufacturing as M800-65A, M800-50A, M400-65A, M400-50A, M300-35A, and NO20. The influence of the cutting methods on the normal magnetization curve, total energy loss and its components, and relative magnetic permeability is investigated in alternating currents using a laboratory single sheet tester. The chemical composition and grain size influence are analyzed and correlated with the magnetic properties. Special attention is devoted to the influence of the increased cutting perimeter on the energy losses and to the way it relates to each chemical alloy constituent. The final decision in what concerns the choice of the proper magnetic material and the specific cutting technology for the motor magnetic cores is imposed by the desired efficiency class and the specific industrial applications. [ABSTRACT FROM AUTHOR]