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1
Grechnev, G. E., A. S. Panfilov, A. V. Fedorchenko, V. A. Desnenko, I. P. Zhuravleva, S. L. Gnatchenko, D. A. Chareev, O. S. Volkova et A. N. Vasiliev. « Electronic Structure and Magnetism of Fe-based Superconductors ». Ukrainian Journal of Physics 57, no 2 (15 février 2012) : 171. http://dx.doi.org/10.15407/ujpe57.2.171.
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Ab initio calculations of the electronic structures are carried out for the novel FeSe1–xTex superconductors to explain the experimentally found anomalous magnetic properties in the normal state. The calculations have shown that FeSe1–xTex systems are close to a magnetic instability with dominating enhanced spin paramagnetism. The magnetic susceptibility is found to increase gradually with the Te content. The temperature dependences of the magnetic susceptibility χ and its anisotropy ∆ χ = χ║ – χ┴ are investigated for FeSe, and a growth of the susceptibility with the temperature is revealed in the temperature range 4.2–300 K. For FeTe, a substantial increase of χ under pressure is found. The calculated paramagnetic susceptibility exhibits a strong dependence on the unit cell volume V and especially the height of chalcogen species from the Fe plane. The calculations have explained the experimental data on χ(T) and χ(P) for FeSe and FeTe, respectively.
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Perez de Lara, David. « Hybrid Superconducting/Magnetic Multifunctional Devices in Two-Dimensional Systems ». Physchem 2, no 4 (25 novembre 2022) : 347–56. http://dx.doi.org/10.3390/physchem2040025.
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The emergence of unexpected properties in two-dimensional materials, interfaces, and nanostructured materials opens an exciting framework for exploring new devices and applications. Recent advances in materials design and the nano structurization of novel, low-dimensional materials, surfaces, and interfaces offer a novel playground to design efficient multifunctional materials-based devices. Low-dimensional materials exhibit peculiarities in their electronic, magnetic, and optical properties, changing with respect to the bulk when they are layered down to a single layer, in addition to their high tunability. Their crystal structure and chemical bonds lead to inherent unique mechanical properties. The fabrication of van der Waals heterostructures by stacking materials with different properties, the better control of interfaces, and the tunability of the physical properties by mechanical strain, and chemical and electronic doping allow for the exploration of multifunctional devices with superconducting, magnetic, and optical properties and unprecedented degrees of freedom in terms of fabrication and tunability.
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Kadioglu, Yelda, Ilkay Ozdemir, Olcay Üzengi Aktürk, Gökhan Gökoğlu, Ümit Akıncı et Ethem Aktürk. « Tuning the electronic structure of RhX3 (X = Cl, Br, I) nonmagnetic monolayers : effects of charge-injection and external strain ». Physical Chemistry Chemical Physics 22, no 8 (2020) : 4561–73. http://dx.doi.org/10.1039/c9cp06240h.
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The electronic and magnetic nature of novel semiconducting RhX3 (X = Cl, Br, I) monolayer systems, which are dynamically and thermally stable, can be tuned by electrical and mechanical modifications.
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KAN, ERJUN, ZHENYU LI et JINLONG YANG. « MAGNETISM IN GRAPHENE SYSTEMS ». Nano 03, no 06 (décembre 2008) : 433–42. http://dx.doi.org/10.1142/s1793292008001350.
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Graphene has attracted great interest in materials science, owing to its novel electronic structures. Recently, magnetism discovered in graphene-based systems has opened up the possibility of their spintronics application. This paper provides a comprehensive review of the magnetic behaviors and electronic structures of graphene systems, including two-dimensional graphene, one-dimensional graphene nanoribbons, and zero-dimensional graphene nanoclusters. Theoretical research suggests that such metal-free magnetism mainly comes from the localized states or edges states. By applying an external electric field, or by chemical modification, we can turn the zigzag nanoribbon systems into half metal, thus obtaining a perfect spin filter.
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Valenzuela, Raúl. « Novel Applications of Ferrites ». Physics Research International 2012 (15 mars 2012) : 1–9. http://dx.doi.org/10.1155/2012/591839.
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The applications of ferrimagnetic oxides, or ferrites, in the last 10 years are reviewed, including thin films and nanoparticles. The general features of the three basic crystal systems and their magnetic structures are briefly discussed, followed by the most interesting applications in electronic circuits as inductors, in high-frequency systems, in power delivering devices, in electromagnetic interference suppression, and in biotechnology. As the field is considerably large, an effort has been made to include the original references discussing each particular application on a more detailed manner.
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Ding, Dawei, Dawei Li, Jing Xia et Zhuang Li. « Novel optimization strategies for isolation structure design in MIMO systems ». IEICE Electronics Express 17, no 8 (2020) : 20200006. http://dx.doi.org/10.1587/elex.17.20200006.
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Zhang, Zijia, Jun Liu et Yansong Li. « Design and Analysis of a Multi-Input Multi-Output System for High Power Based on Improved Magnetic Coupling Structure ». Energies 15, no 5 (24 février 2022) : 1684. http://dx.doi.org/10.3390/en15051684.
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Conventional inductive contactless power transfer (ICPT) systems have only one energy transmission path, which makes it challenging to meet the power transmission requirements of high-power and reliability. This study proposes a novel multiple-input multiple-output (MIMO) ICPT system. The three-dimensional finite element analysis tool COMSOL is utilised to study various magnetic coupling structures, analyse the influence of cross-coupling between coils on the same side, design the circuit based on this, propose a parameter configuration method for resonance compensation, and, finally, build an experimental platform with small magnetic coupling structures for single-input single-output systems (SISO) and MIMO systems. The results indicate that the co-directional connection of the coils of the E-shaped and UE-shaped magnetic coupling structures has a strengthening effect on the secondary side coupling. The magnetic coupling structure of the E-shaped iron core exhibits the best transmission performance. The transmission power of the MIMO system with the E-shaped magnetic coupling structure as the core device is significantly improved. In addition, the output power is unchanged after a secondary side fault, which verifies the accuracy of the proposed method.
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Ying, Yu, Ke Xu, Guang-Yuan Si et Ji-Zhong Zhao. « Simulation and Experiment Study of Chain Aggregate Structure in Magnetic Fluid ». Integrated Ferroelectrics 201, no 1 (2 septembre 2019) : 110–19. http://dx.doi.org/10.1080/10584587.2019.1668695.
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Magnetic fluid is a novel magnetic functional material. The magneto-optical properties are displayed due to the tunability. In the paper, the material characterization was studied theoretically and experimentally. In the simulation, a rod-like magnetic nanoparticle model was used to simulate the motion of the magnetic particles. In the experiment, an experimental setup was designed to observe the change of the microstructure. The results showed that the magnetic particles can be aggregated to form several magnetic chains when the applied magnetic field exceeded 100 Oe. The novel magneto-optical device exhibits advantages of low cost, small size, and easy formation.
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Parks, Daniel, Karim Niang, Yuri Janssen et Jack W. Simonson. « Synthesis and Crystal Structure of Zr3V3GeSn4 ». Crystals 13, no 5 (29 avril 2023) : 744. http://dx.doi.org/10.3390/cryst13050744.
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Quantum fluctuations inherent in electronic systems positioned close to magnetic instabilities can lead to novel collective phenomena. One such material, β-Ti6Sn5, sits close to ferromagnetic (FM) instability and can be pushed to an itinerant FM-ordered state with only minute magnetic or non-magnetic doping. The binary nature of this compound, however, limits the tuning variables that can be applied to study any emergent physics, which are likely to be sensitive to the introduction of chemical disorder.Accordingly, we grew high-quality single crystals of a new quaternary compound Zr3V3GeSn4 from a Sn-rich self flux, and determined the structure with single-crystal X-ray diffraction. Zr3V3GeSn4 forms in an ordered derivative of the hexagonal β-Ti6Sn5 structure with Zr and V atomic positions that show no indication of site interchange. Ge likewise occupies a single unique atomic position. The V site, which would be the one most likely to give rise to any magnetic character, is located at the center of a distorted octahedron of Sn, with such octahedra arranged in face-sharing chains along the crystallographic c axis, while the chains themselves are organized in a kagome geometry. Zr3V3GeSn4 represents the second known quaternary phase within this system, suggesting that other compounds with this structure type await discovery.
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Yang, Bo, Xiaoyong Gao et Cheng Li. « A Novel Micromachined Z-axis Torsional Accelerometer Based on the Tunneling Magnetoresistive Effect ». Micromachines 11, no 4 (17 avril 2020) : 422. http://dx.doi.org/10.3390/mi11040422.
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A novel micromachined z-axis torsional accelerometer based on the tunneling magnetoresistive effect is presented in this paper. The plane main structure bonded with permanent magnetic film is driven to twist under the action of inertial acceleration, which results in the opposite variation of the magnetic field intensity. The variation of the magnetic field is measured by two differential tunneling magnetoresistive sensors arranged on the top substrate respectively. Electrostatic feedback electrodes plated on the bottom substrate are used to revert the plane main structure to an equilibrium state and realize the closed-loop detection of acceleration. A modal simulation of the micromachined z-axis tunneling magnetoresistive accelerometer was implemented to verify the theoretical formula and the structural optimization. Simultaneously, the characteristics of the magnetic field were analyzed to optimize the layout of the tunneling magnetoresistance accelerometer by finite element simulation. The plane main structure, fabricated with the process of standard deep dry silicon on glass (DDSOG), had dimensions of 8000 μm (length) × 8000 μm (width) × 120μm (height). A prototype of the micromachined z-axis tunneling magnetoresistive accelerometer was produced by micro-assembly of the plane main structure with the tunneling magnetoresistive sensors. The experiment results demonstrate that the prototype has a maximal sensitivity of 1.7 mV/g and an acceleration resolution of 128 μg/Hz0.5 along the z-axis sensitive direction.
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Qian, Leping, et Decai Li. « Use of Magnetic Fluid in Accelerometers ». Journal of Sensors 2014 (2014) : 1–9. http://dx.doi.org/10.1155/2014/375623.
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Magnetic fluid accelerometer is designed based on the special physical properties of magnetic fluid. Compared with the conventional acceleration sensors, magnetic fluid accelerometer has stronger shock resistance capability, higher sensitivity, lower energy consumption, and better performance in low frequency response. It satisfies the growing requirements of acceleration sensors. In this paper, the dynamic model and the theory of magnetic fluid accelerometers were presented. The structure characteristics of typical magnetic fluid accelerometers were investigated, and the development trend of magnetic fluid accelerometers in the future was also predicted. Besides, a novel accelerometer with linearity better than 1.5% and sensitivity better than 75 mV/g was proposed.
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Vinko, Davor, Domagoj Bilandžija et Vanja Mandrić Radivojević. « Optimization of a Two-Layer 3D Coil Structure with Uniform Magnetic Field ». Wireless Power Transfer 2021 (14 octobre 2021) : 1–11. http://dx.doi.org/10.1155/2021/6303628.
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Conventional magnetically coupled resonant wireless power transfer systems are faced with resonant frequency splitting phenomena and impedance mismatch when a receiving coil is placed at misaligned position. These problems can be avoided by using uniform magnetic field distribution at receiving plane. In this paper, a novel 3D transmitting coil structure with improved uniform magnetic field distribution is proposed based on a developed optimization method. The goal is to maximize the average magnetic field strength and uniform magnetic field section of the receiving plane. Hence, figures of merit (FoM1 and FoM2) are introduced and defined as product of average magnetic field strength and length or surface along which uniform magnetic field is generated, respectively. The validity of the optimization method is verified through laboratory measurements performed on the fabricated coils driven by signal generator at operating frequency of 150 kHz. Depending on the allowed ripple value and predefined coil proportions, the proposed transmitting coil structure gives the uniform magnetic field distribution across 50% to 90% of the receiving plane.
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Abboud, M., D. H. Ozbey, M. E. Kilic et E. Durgun. « Investigation of anisotropic mechanical, electronic, and charge carrier transport properties of germanium-pnictogen monolayers ». Journal of Physics D : Applied Physics 55, no 18 (4 février 2022) : 185302. http://dx.doi.org/10.1088/1361-6463/ac4cf9.
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Abstract Recently, novel two-dimensional (2D) GeP and GeAs systems have been fabricated by mechanical exfoliation and utilized in various applications. These developments have brought the 2D germanium-pnictogens, C2/m-GeX (X = N, P, As, Sb, and Bi) structures into the limelight. In this study, we systematically investigate the structural, mechanical, electronic, and charge carrier transport properties of GeX monolayers by using first-principles methods. Our results show that the considered systems are dynamically stable and possess anisotropic physical properties. Examined structures are found to be flexible, and their mechanical strength and stiffness decrease down the group-V, in line with the trends of the bond strength, cohesive energy, charge transfer, and electron localization function. Additionally, the zigzag in-plane direction is mechanically superior to the armchair direction. The electronic band structure calculations based on HSE06 hybrid functional with the inclusion of spin–orbit coupling indicate that GeX monolayers are either direct or quasi-direct semiconductors with band gaps lying within the infrared and visible spectrum. The estimated charge carrier mobilities are highly anisotropic and also differ significantly depending on the structure and carrier type. These unique properties render GeX monolayers as suitable 2D materials for flexible nanoelectronic applications.
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Liu, Ming, et Nian X. Sun. « Voltage control of magnetism in multiferroic heterostructures ». Philosophical Transactions of the Royal Society A : Mathematical, Physical and Engineering Sciences 372, no 2009 (28 février 2014) : 20120439. http://dx.doi.org/10.1098/rsta.2012.0439.
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Electrical tuning of magnetism is of great fundamental and technical importance for fast, compact and ultra-low power electronic devices. Multiferroics, simultaneously exhibiting ferroelectricity and ferromagnetism, have attracted much interest owing to the capability of controlling magnetism by an electric field through magnetoelectric (ME) coupling. In particular, strong strain-mediated ME interaction observed in layered multiferroic heterostructures makes it practically possible for realizing electrically reconfigurable microwave devices, ultra-low power electronics and magnetoelectric random access memories (MERAMs). In this review, we demonstrate this remarkable E-field manipulation of magnetism in various multiferroic composite systems, aiming at the creation of novel compact, lightweight, energy-efficient and tunable electronic and microwave devices. First of all, tunable microwave devices are demonstrated based on ferrite/ferroelectric and magnetic-metal/ferroelectric composites, showing giant ferromagnetic resonance (FMR) tunability with narrow FMR linewidth. Then, E-field manipulation of magnetoresistance in multiferroic anisotropic magnetoresistance and giant magnetoresistance devices for achieving low-power electronic devices is discussed. Finally, E-field control of exchange-bias and deterministic magnetization switching is demonstrated in exchange-coupled antiferromagnetic/ferromagnetic/ferroelectric multiferroic hetero-structures at room temperature, indicating an important step towards MERAMs. In addition, recent progress in electrically non-volatile tuning of magnetic states is also presented. These tunable multiferroic heterostructures and devices provide great opportunities for next-generation reconfigurable radio frequency/microwave communication systems and radars, spintronics, sensors and memories.
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Werner, Robin, Jaroslaw Kita, Michael Gollner, Florian Linseis et Ralf Moos. « Novel, low-cost device to simultaneously measure the electrical conductivity and the Hall coefficient from room temperature up to 600 °C ». Journal of Sensors and Sensor Systems 10, no 1 (19 mars 2021) : 71–81. http://dx.doi.org/10.5194/jsss-10-71-2021.
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Abstract. A novel measurement device for simultaneous high temperature measurements of the electrical conductivity and the Hall coefficient has been developed. Simulations were used to design a suitable screen-printed planar platinum heating structure that generates temperatures of up to 600 ∘C by Joule heating. Simulations of the temperature distribution have been validated using thermal imaging. With the hardware setup of two permanent magnetic yoke systems with a magnetic flux density of ±760 mT, the electrical conductivity and the charge carrier densities of a silicon wafer and a gold film were measured, as examples of a typical semiconductor with low charge carrier densities but high mobility and a metal representing materials with very high charge carrier densities but moderate mobilities, respectively. Measurements were compared with data from the literature to validate the functionality of the novel, low-cost measurement device.
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Jadaun, Priyamvada, et Bart Soreé. « Review of Orbital Magnetism in Graphene-Based Moiré Materials ». Magnetism 3, no 3 (28 août 2023) : 245–58. http://dx.doi.org/10.3390/magnetism3030019.
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Recent years have seen the emergence of moiré materials as an attractive platform for observing a host of novel correlated and topological phenomena. Moiré heterostructures are generated when layers of van der Waals materials are stacked such that consecutive layers are slightly mismatched in their lattice orientation or unit cell size. This slight lattice mismatch gives rise to a long-wavelength moiré pattern that modulates the electronic structure and leads to novel physics. The moiré superlattice results in flat superlattice bands, electron–electron interactions and non-trivial topology that have led to the observation of superconductivity, the quantum anomalous Hall effect and orbital magnetization, among other interesting properties. This review focuses on the experimental observation and theoretical analysis of orbital magnetism in moiré materials. These systems are novel in their ability to host magnetism that is dominated by the orbital magnetic moment of Bloch electrons. This orbital magnetic moment is easily tunable using external electric fields and carrier concentration since it originates in the quantum anomalous Hall effect. As a result, the orbital magnetism found in moiré superlattices can be highly attractive for a wide array of applications including spintronics, ultra-low-power magnetic memories, spin-based neuromorphic computing and quantum information technology.
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Zhao, Xiang, Mu Zhang, Wei Pan, Rui Yang et Xu-Dong Sun. « Construction of N-Doped Hollow Carbon Nanospheres Through a Novel Self-Template Strategy as High-Performance Electrode Materials for Supercapacitors ». Journal of Nanoelectronics and Optoelectronics 16, no 8 (1 août 2021) : 1189–98. http://dx.doi.org/10.1166/jno.2021.3066.
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N-doped hollow carbon nanospheres (NHCSs) with mesopores-rich hierarchical structure have been synthesized by a self-template strategy using resorcinol-formaldehyde resin as precursors. The crucial point of this strategy is the selective dissolution of acetones for oligomers and subsequent rearrangement dependent on the structure-directing agent (CTAB). The large specific surface area (1325.0 m2 g−1), abundant and accessible mesopores (6.6 nm), unexpected nitrogen doping concentration (3.5 wt.%), and favorable graphitization (0.88), enable the as-prepared NHCSs to be a candidate for energy storage materials. When utilized as supercapacitor electrode, the NHCSs exhibit high specific capacitance of 293.1 F g−1 at 0.5 A g−1, impressive rate performance of 225.0 F g−1 at 20 A g−1, and good cycling performance (over 88.24% the peak capacity was retained after 5000 cycles at 5 A g−1). The self-template strategy displays potential prospects as a versatile route to reconstruct porous structures of carbon materials from phenolic resin polymers, thereby broadening the applications in drug delivery, adsorption, and energy storage systems.
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Olivas, Richard, Rudy Salas, Dan Muse, Eric MacDonald, Ryan Wicker, Mike Newton et Ken Church. « Structural Electronics through Additive Manufacturing and Micro-Dispensing ». International Symposium on Microelectronics 2010, no 1 (1 janvier 2010) : 000940–46. http://dx.doi.org/10.4071/isom-2010-tha5-paper6.
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Implementing electronics systems that are conformal with curved and complex surfaces is difficult if not impossible with traditional fabrication techniques, which require stiff, two dimensional printed circuit boards (PCB). Flexible copper based fabrication is currently available commercially providing conformance, but not simultaneously stiffness. Consequently, these systems are susceptible to reliability problems if bent or stretched repeatedly. The integration of Additive Manufacturing (AM) combined with Direct Print (DP) micro-dispensing can provide shapes of arbitrary and complex form which incorporate 1) miniature cavities for insetting electronic components and 2) conductive traces for electrical interconnect between components. The fabrication freedom introduced by AM techniques such as stereolithography (SL), ultrasonic consolidation (UC), and fused deposition modeling (FDM) have only recently been explored in the context of electronics integration. Advanced dispensing processes have been integrated into these systems allowing for the introduction of conductive inks to serve as electrical interconnect within intricately-detailed dielectric structures. This paper describes a process that provides a novel approach for the fabrication of stiff conformal structures with integrated electronics and describes several prototype demonstrations: a body conformal helmet insert for detection of Traumatic Brain Injury (TBI), a 3D magnetic flux sensor with LED indicators for magnitude and direction and a floating sensor capable of detecting impurities in water while maintaining orientation through density gradients.
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Yao, Weichong, Junwei Lu, Foad Taghizadeh, Feifei Bai et Andrew Seagar. « Integration of SiC Devices and High-Frequency Transformer for High-Power Renewable Energy Applications ». Energies 16, no 3 (3 février 2023) : 1538. http://dx.doi.org/10.3390/en16031538.
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This paper presents a novel structure of Integrated SiC MOSFETs with a high-frequency transformer (I-SiC-HFT) for various high-power isolated DC–DC converters. Several resonant converters are considered for integration in this paper, including the phase-shift full-bridge (PSFB) converter, inductor–inductor–capacitor (LLC) resonant converter, bidirectional PSFB converter, and capacitor–inductor–inductor–capacitor (CLLC) resonant converter. The applications of I-SiC-HFT are focused on V2G EV battery charging systems, energy storage in DC and AC microgrids, and renewable energy systems. SiC devices, including MOSFETs, Schottky diodes, and MOSFET modules, are used in this novel structure of I-SiC-HFT. The high-frequency magnetic structure uses distributed ferrite cores to form a large central space to accommodate SiC devices. The optimized architecture of I-SiC-HFT and heatsink structure is proposed for thermal management of SiC devices. To prove the concept, a small-scale 1.5 kW prototype I-SiC-HFT is used to demonstrate the basic structure and various performance indicators through the FEM based electromagnetic simulation and DC–DC converter experiments.
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Padma, Chennagiri Rajarao, et Dr K. M. Ravikumar. « Low-cost Magnetic Resonance Console Architecture using an Open Source for Laboratory Scale Systems ». International Journal of Innovative Technology and Exploring Engineering 12, no 2 (30 janvier 2023) : 26–32. http://dx.doi.org/10.35940/ijitee.b9413.0112223.
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MRI systems with proprietary hardware must use pulse programming, which is less expensive. Pulse programming consoles use Digital Signal Processor, Complex Programming Logic Device, and microcontrollers, which are typically restricted to particular architectures. General–purpose, extremely affordable electronics board featuring these architectures are now capable enough to be directly implemented in MRI consoles. Here we present the architectural details of various consoles with novel designs and their limitations. Finally, we propose a console design which was created utilising widely accessible Arduino Boards to connect to Pulseq-GPI implementations at a reduced cost of $225
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Liimatainen, Helmi, Teemu O. Pennanen et Juha Vaara. « 1H chemical shifts in nonaxial, paramagnetic chromium(III) complexes — Application of novel pNMR shift theory ». Canadian Journal of Chemistry 87, no 7 (juillet 2009) : 954–64. http://dx.doi.org/10.1139/v09-045.
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We present the first chemical application of the recent, general theory of the nuclear magnetic resonance shielding and chemical shift in paramagnetic compounds, to a set of nonaxial high-spin metallo-organic complexes. The theory is for the first time rigorous for systems of arbitrary spatial and spin symmetry, and introduces new structure to the isotropic, anisotropic but symmetric, and anisotropic and antisymmetric parts of the shielding tensor. We apply the theory using density functional calculations of the proton chemical shift in a family of nonaxial chromium(III) complexes possessing a quartet ground electronic spin state. We discuss the various contributions to the isotropic chemical shift, and compare the full theory to approximate forms appropriate to the doublet case on the one hand, and to the doublet case at the nonrelativistic limit, on the other hand. The performance of various exchange-correlation functionals in reproducing the recently measured experimental chemical shifts is evaluated.
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Liu, Wenyao, Wei Li, Chenxi Liu, Enbo Xing, Yanru Zhou, Lai Liu et Jun Tang. « A High-Sensitivity Resonant Magnetic Sensor Based on Graphene Nanomechanical Resonator ». Micromachines 13, no 4 (16 avril 2022) : 628. http://dx.doi.org/10.3390/mi13040628.
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This paper presents a novel resonant magnetic sensor consisting of a graphene nanomechanical oscillator and magnetostrictive stress coupling structure, using Si/SiO2 substrate and Fe–Ga alloy, respectively. In this device, the deformation of the Fe–Ga alloy resulting from the external magnetic field changed the surface tension of the graphene, resulting in a significant change in the resonance frequency of graphene. Using the finite element analysis, it could be found that the response of the resonance frequency revealed a good linear relationship with the external magnetic field (along the x-axis) in the range of the 1 to 1.6 mT. By optimizing the sizes of each component of the magnetic sensor, such as the thickness of the Si/SiO2 substrate and the Fe–Ga alloy, and the length of the graphene, the sensitivity could even reach 834 kHz/mT, which is three orders of magnitude higher than conventional resonant magnetic devices. This provides a new method for highly sensitive and miniaturized magnetic sensors.
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Tan Fenli, 谭奋利, 曾晨欣 Zeng Chenxin, 冯安伟 Feng Anwei, 赵世家 Zhao Shijia et 季轶群 Ji Yiqun. « 基于Dyson结构的新型快照式分光成像系统光学设计 ». Acta Optica Sinica 42, no 4 (2022) : 0422002. http://dx.doi.org/10.3788/aos202242.0422002.
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Jūrėnas, Vytautas, Gražvydas Kazokaitis et Dalius Mažeika. « 3DOF Ultrasonic Motor with Two Piezoelectric Rings ». Sensors 20, no 3 (4 février 2020) : 834. http://dx.doi.org/10.3390/s20030834.
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A novel design of a multiple degrees of freedom (multi-DOF) piezoelectric ultrasonic motor (USM) is presented in the paper. The main idea of the motor design is to combine the magnetic sphere type rotor and two oppositely placed ring-shaped piezoelectric actuators into one mechanism. Such a structure increases impact force and allows rotation of the sphere with higher torque. The main purpose of USM development was to design a motor for attitude control systems used in small satellites. A permanent magnetic sphere with a magnetic dipole is used for orientation and positioning when the sphere is rotated to the desired position and the magnetic field synchronizes with the Earth’s magnetic dipole. Also, the proposed motor can be installed and used for robotic systems, laser beam manipulation, etc. The system has a minimal number of components, small weight, and high reliability. Numerical simulation and experimental studies were used to verify the operating principles of the USM. Numerical simulation of a piezoelectric actuator was used to perform modal frequency and harmonic response analysis. Experimental studies were performed to measure both mechanical and electrical characteristics of the piezoelectric motor.
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Geng, Tao, Jihao Wang, Wenjie Meng, Jing Zhang, Qiyuan Feng, Yubin Hou et Qingyou Lu. « A Novel Atomically Resolved Scanning Tunneling Microscope Capable of Working in Cryogen-Free Superconducting Magnet ». Micromachines 14, no 3 (11 mars 2023) : 637. http://dx.doi.org/10.3390/mi14030637.
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We present a novel homebuilt scanning tunneling microscope (STM) with atomic resolution integrated into a cryogen-free superconducting magnet system with a variable temperature insert. The STM head is designed as a nested structure of double piezoelectric tubes (PTs), which are connected coaxially through a sapphire frame whose top has a sample stage. A single shaft made of tantalum, with the STM tip on top, is held firmly by a spring strip inside the internal PT. The external PT drives the shaft to the tip–sample junction based on the SpiderDrive principle, and the internal PT completes the subsequent scanning and imaging work. The STM head is simple, compact, and easy to assemble. The excellent performance of the device was demonstrated by obtaining atomic-resolution images of graphite and low drift rates of 30.2 pm/min and 41.4 pm/min in the X–Y plane and Z direction, respectively, at 300K. In addition, we cooled the sample to 1.6 K and took atomic-resolution images of graphite and NbSe2. Finally, we performed a magnetic field sweep test from 0 T to 9 T at 70 K, obtaining distinct graphite images with atomic resolution under varying magnetic fields. These experiments show our newly developed STM’s high stability, vibration resistance, and immunity to high magnetic fields.
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Alim, Mohammad A. « Electrical Characterization of Engineering Materials ». Active and Passive Electronic Components 19, no 3 (1996) : 139–69. http://dx.doi.org/10.1155/1996/76148.
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Engineering material systems for smart components and novel device applications require a thorough understanding on the structure-property-processing relationships to optimize their performance. The factors determining performance characteristics of the multi-phase/component heterogeneous polycrystalline hybrid (MPCHPH) systems are not identical to devices based on single-crystal/single-junction (SCSJ) technology. Performing SCSJ-like data-analysis on the MPCHPH systems can lead to confusion in delineating simultaneously operative phenomena when “physical geometrical factors”are used in normalizing the as-measuredelectrical parametersorelectrical quantities. Such an analytical approach can vitiate interpretation when microstructural inhomogeneity plays a key role in determining the electrical path. The advantage of using the as-measuredelectrical parametersorelectrical quantitiesconstituting the “immittance function” is emphasized. The “state of normalization” usingphysical geometrical factorscan only be executed for a specific phenomenon when isolated from the total electrical behavior.
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Cui, Yepu, Eui Min Jung, Ajibayo Adeyeye, Charles Lynch, Xuanke He et Manos Tentzeris. « Additively Manufactured RF Devices for 5G, IoT, RFID, WSN, and Smart City Applications ». International Journal of High Speed Electronics and Systems 29, no 01n04 (mars 2020) : 2040016. http://dx.doi.org/10.1142/s0129156420400169.
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With the development of inkjet-/3D-/4D-printing additive manufacturing technologies, flexible 3D substrate with complex structures can be patterned with dielectric, conductive and semi-conductive materials to realize novel RF designs. This paper provides a review of state-of-the-art additively manufactured passive RF devices including antennas and frequency selective surfaces (FSS), couplers, where origami-inspired structure enables unprecedented capabilities of on-demand continuous frequency tunability and deployability. This paper also discusses additively manufactured active RF modules and systems such as inkjet printed RF energy harvester system with high sensitivity and efficiency for Internet of Things (IoT), smart cities and wireless sensor networks (WSN) applications, inkjet-printed RF front ends, and inkjet-printed mm-wave backscatter modules.
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Heya, Akira, et Katsuhiro Hirata. « Experimental Verification of Three-Degree-of-Freedom Electromagnetic Actuator for Image Stabilization ». Sensors 20, no 9 (27 avril 2020) : 2485. http://dx.doi.org/10.3390/s20092485.
Texte intégralRésumé :
Image deteriorations due to vibrations have become a problem in autonomous systems such as unmanned aerial vehicles, robots, and autonomous cars. To suppress the vibration, a camera stabilizer using a gimbal mechanism is widely used. However, the size and weight of the system increase because the conventional image stabilization systems require some actuators and links to drive in multi-axes. In order to solve these problems, we proposed a novel three-degree-of-freedom (3DOF) electromagnetic actuator for image stabilization. The actuator can be driven by only three-phase and has a simple structure and control system. This paper describes the experimental verification of the proposed actuator. The torque characteristics are clarified, and the analysis and measured torque characteristics are compared to verify the analysis validity. For verifying the dynamic performance, the frequency characteristics are measured. The effectiveness of the proposed magnetic structure and operating principle are investigated.
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Bravo-García, Laura, Edurne S. Larrea, Beñat Artetxe, Luis Lezama, Juan M. Gutiérrez-Zorrilla et María I. Arriortua. « Structural Transformations in the Thermal Dehydration of [Cu2(bpa)(btec)(H2O)4]n Coordination Polymer ». Molecules 24, no 9 (13 mai 2019) : 1840. http://dx.doi.org/10.3390/molecules24091840.
Texte intégralRésumé :
Reactions between pyridinic ligands such as 1,2-bis(4-pyridyl)ethane (bpa) and transition metal cations are a very widespread technique to produce extended coordination polymers such as Metal-Organic Frameworks. In combination with a second ligand these systems could present different topologies and behaviors. In this context, the use of 1,2,4,5-benzenetetracarboxylic acid (H4btec) gave us a novel 2D compound, [Cu2(bpa)(btec)(H2O)4]n (1), which was prepared by microwave-assisted synthesis and structurally characterized by means of single crystal X-ray diffraction. Its thermal behavior was analyzed through thermogravimetric analysis and variable temperature powder X-ray diffraction, concluding that thermal stability is influenced by the coordination water molecules, allowing two sequential thermochromic phase transformations to take place. These transformations were monitored by electronic paramagnetic resonance spectroscopy and magnetic susceptibility measurements. In addition, the crystal structure of the anhydrous compound [Cu2(bpa)(btec)]n (1.ah) was determined. Finally, a topological study was carried out for the bpa ligand considering all the structures deposited in the Cambridge Structural Databased. More than 1000 structures were analyzed and classified into 17 different topologies, according to the role of the ligand.
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Zhu, Junhui, Siyuan Meng, Yong Wang, Ming Pang, Zhiping Hu et Changhai Ru. « A Novel Monopolar Cross-Scale Nanopositioning Stage Based on Dual Piezoelectric Stick-Slip Driving Principle ». Micromachines 13, no 11 (18 novembre 2022) : 2008. http://dx.doi.org/10.3390/mi13112008.
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The precise characterization and measurement of new nanomaterials and nano devices require in situ SEM nanorobotic instrumentation systems, which put forward further technical requirements on nanopositioning techniques of compact structure, cross-scale, nanometer accuracy, high vacuum and non-magnetic environment compatibility, etc. In this work, a novel cross-scale nanopositioning stage was proposed, which combined the advantages of piezoelectric stick-slip positioner and piezoelectric scanner techniques and adopted the idea of macro/micro positioning. A new structure design of a single flexible hinge shared by a small and large PZT was proposed to effectively reduce the size of the positioning stage and achieve millimeter stroke and nanometer motion positioning accuracy. Then, the cross-scale motion generation mechanism of the dual piezoelectric stick-slip drive was studied, the system-level dynamics model of the proposed positioning stages was constructed, and the mechanism design was optimized. Further, a prototype was manufactured and a series of experiments were carried out to test the performance of the stage. The results show that the proposed positioning stage has a maximum motion range of 20 mm and minimum step length of 70 nm under the small piezoceramic ceramic macro-motion stepping mode, and a maximum scanning range of 4.9 μm and motion resolution of 16 nm under the large piezoceramic ceramic micro-motion scanning mode. Moreover, the proposed stage has a compact structure size of 30 × 17 × 8 mm3, with a maximum motion speed of 10 mm/s and maximum load of 2 kg. The experimental results confirm the feasibility of the proposed stage, and nanometer positioning resolution, high accuracy, high speed, and a large travel range were achieved, which demonstrates that the proposed stage has significant performance and potential for many in situ SEM nanorobotic instrument systems.
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Khitun, Alexander. « Magnetic Interconnects Based on Composite Multiferroics ». Micromachines 13, no 11 (17 novembre 2022) : 1991. http://dx.doi.org/10.3390/mi13111991.
Texte intégralRésumé :
The development of magnetic logic devices dictates a need for a novel type of interconnect for magnetic signal transmission. Fast signal damping is one of the problems which drastically differs from conventional electric technology. Here, we describe a magnetic interconnect based on a composite multiferroic comprising piezoelectric and magnetostrictive materials. Internal signal amplification is the main reason for using multiferroic material, where a portion of energy can be transferred from electric to magnetic domains via stress-mediated coupling. The utilization of composite multiferroics consisting of piezoelectric and magnetostrictive materials offers flexibility for the separate adjustment of electric and magnetic characteristics. The structure of the proposed interconnect resembles a parallel plate capacitor filled with a piezoelectric, where one of the plates comprises a magnetoelastic material. An electric field applied across the plates of the capacitor produces stress, which, in turn, affects the magnetic properties of the magnetostrictive material. The charging of the capacitor from one edge results in the charge diffusion accompanied by the magnetization change in the magnetostrictive layer. This enables the amplitude of the magnetic signal to remain constant during the propagation. The operation of the proposed interconnects is illustrated by numerical modeling. The model is based on the Landau–Lifshitz–Gilbert equation with the electric field-dependent anisotropy term included. A variety of magnetic logic devices and architectures can benefit from the proposed interconnects, as they provide reliable and low-energy-consuming data transmission. According to the estimates, the group velocity of magnetic signals may be up to 105 m/s with energy dissipation less than 10−18 J per bit per 100 nm. The physical limits and practical challenges of the proposed approach are also discussed.
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Guo, Lei, Lishuai Zhang, Yuan Song, Liang Zhao et Qiancheng Zhao. « Design and Implementation of a Novel Tilt Sensor Based on the Principle of Variable Reluctance ». Sensors 19, no 23 (28 novembre 2019) : 5228. http://dx.doi.org/10.3390/s19235228.
Texte intégralRésumé :
Tilt angle measurement in dynamic systems is problematic because the rotation of the measured platform is coupled with translation. Therefore, when some sensors are applied in dynamic systems, their output signals are often submerged in the noise signals generated by translation. To enhance the ability of tilt sensors to resist translational noise, a dynamic tilt sensor is proposed based on the principle of variable reluctance from the perspective of sensor structure. The eccentric structure of the sensor constructed with a shell, liquid, and internal damping plate was designed according to the principles of mechanics. The characteristic of translational acceleration restraint determined by the sensor structure was established theoretically. In addition, the magnetic circuit of the sensor was analyzed to illustrate the sensor’s working principles. A Clapp oscillator circuit was designed to convert mechanical motion into a measureable electrical signal. A method to determine the sensor’s direction of rotation is proposed. A waveform conversion circuit was designed to convert the sine wave output of the Clapp oscillator to a square wave, and a square-wave frequency measurement circuit was designed based on the C8051 micro-control unit. A translation–rotation experimental hardware platform was constructed. The data acquisition program was designed on a PC platform, and the translation–rotation experiments were conducted with an MTi attitude measurement unit as a reference. The validity of the tilt angle measurements and the effect of the translational acceleration restraint of the sensor were verified by the experimental data. The theoretical results obtained were consistent with the experimental data, verifying the validity of the theoretical analysis and experimental devices employed. A measurement range of −180 to 180° was achieved.
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Riouch, Tariq, et Cristian Nichita. « Design and control of DFIG with SMES storage under symmetrical grid fault ». International Journal of Power Electronics and Drive Systems (IJPEDS) 14, no 1 (1 mars 2023) : 453. http://dx.doi.org/10.11591/ijpeds.v14.i1.pp453-460.
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<span lang="EN-US">This paper presents a novel design and robust control for wind conversion systems using DFIG. The system is designed to reduce the problems related to the sudden variation of the wind speed and to improve the sensitivity of the DFIG to grid faults to avoid disconnection of the wind system from the electrical grid. To enhance the DFIG behavior, power fluctuation and to protect power devices under symmetrical faults, a specific superconducting magnetic energy storage (SMES) scheme and its control are proposed. To validate this study, the control structure and strategies were implemented in the MATLAB/Simulink environment. The results obtained by simulation were compared with those using traditional control strategies, they highlight an improvement in the functioning of wind conversion systems of this type, showing the rigor and effectiveness of the proposed strategy.</span>
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Jordan, Zachary, Shahriar N. Khan, Benjamin A. Jackson et Evangelos Miliordos. « Can boron form coordination complexes with diffuse electrons ? Evidence for linked solvated electron precursors ». Electronic Structure 4, no 1 (26 janvier 2022) : 015001. http://dx.doi.org/10.1088/2516-1075/ac495c.
Texte intégralRésumé :
Abstract Density functional theory and ab initio multi-reference calculations are performed to examine the stability and electronic structure of boron complexes that host diffuse electrons in their periphery. Such complexes (solvated electron precursors or SEPs) have been experimentally identified and studied theoretically for several s- and d-block metals. For the first time, we demonstrate that a p-block metalloid element can form a stable SEP when appropriate ligands are chosen. We show that three ammonia and one methyl ligands can displace two of the three boron valence electrons to a peripheral 1s-type orbital. The shell model for these outer electrons is identical to previous SEP systems (1s, 1p, 1d, 2s). Further, we preformed the first examination of a molecular system consisting of two SEPs bridged by a hydrocarbon chain. The electronic structure of these dimers is very similar to that of traditional diatomic molecules forming bonding and anti-bonding σ and π orbitals. Their ground state electronic structure resembles that of two He atoms, and our results indicate that the excitation energies are nearly independent of the chain length for four carbon atoms or longer. These findings pave the way for the development of novel materials similar to expanded metals and electrides.
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Sarabi, Behrouz Kheiri, Manu Sharma, Damanjeet Kaur et Navin Kumar. « A novel technique for generating desired vibrations in structure ». Integrated Ferroelectrics 176, no 1 (21 novembre 2016) : 236–50. http://dx.doi.org/10.1080/10584587.2016.1252654.
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Zhang, Jiaxu, Junfeng Liu et Hongbing Wu. « Research on a Novel High-Torque-Density Axial–Radial-Flux Permanent-Magnet Motor with Annular Winding for an Elevator-Traction Machine ». Electronics 12, no 13 (28 juin 2023) : 2867. http://dx.doi.org/10.3390/electronics12132867.
Texte intégralRésumé :
The traditional radial flux PMSM and axial flux PMSM have an effective air gap on only one side, between the stator and rotor, and only the effective air gap generates electromagnetic torque. There are defects in the magnetic-field utilization, and it is difficult to improve the torque density. Therefore, this paper proposes an axial–radial-flux permanent-magnet synchronous motor (ARF-PMSM), which combines radial flux with axial flux, to be used in an elevator-traction machine-drive motor. The characteristics of the ARF-PMSM are that the stator core is made of a soft magnetic composite material and the winding is annular. The motor has three effective air gaps, which can achieve high torque density without increasing the overall dimensions. In this paper, the mechanical structure and operation mechanism of the ARF-PMSM are introduced, and the characteristics of its magnetic circuit structure are analyzed by using the equivalent magnetic circuit method. The torque characteristics and other electromagnetic characteristics of the ARF-PMSM, the traditional surface-mounted PMSM, and the spoke-type PMSM are compared and analyzed using the finite element method. The research results show that the proposed motor has high torque density, which provides a new design idea in the form of a high-torque-density PMSM for use in elevator-traction machines.
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Fowler, P. W., H. M. Kelly, P. Lazzeretti, M. Malagoli et R. Zanasi. « THEORETICAL DETERMINATION OF THE ELECTRIC DIPOLE AND QUADRUPOLE RESPONSE PROPERTIES OF C60 ». International Journal of Modern Physics B 06, no 23n24 (décembre 1992) : 3903–7. http://dx.doi.org/10.1142/s0217979292001985.
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The electronic structures of the fullerenes, characterized by π-electron systems spread over a closed surface, may exhibit novel responses to external electric and magnetic fields. Accurate theoretical determination of such properties is made difficult by the large number of electrons, but for some systems, in particular C 60, the molecular symmetry can be taken into account to achieve significant reduction in computer effort. A method has been developed that permits the use of the full molecular point group symmetry in the calculation of perturbed electron. density matrices transforming as second-rank tensors. In this note preliminary coupled Hartree-Fock results in a minimal basis for static electric response properties of C 60 (the second electric dipole hyperpolarizability γ, the electric quadrupole polarizability C and the first electric (mixed) dipole-quadrupole hyperpolarizability B) are presented.
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Liu, Zhirong, Min Zhu, Caihua Xu, Wenqi Bao, Liqiang Xie, Haitao Zhang et Yueqi Han. « Electric field sensing characteristics of ZnO/SiO2/Si surface acoustic wave devices ». Journal of Micromechanics and Microengineering 32, no 5 (17 mars 2022) : 055001. http://dx.doi.org/10.1088/1361-6439/ac5b1c.
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Abstract Existing microelectro mechanical systems (MEMSs) electric field sensors have movable parts and electronic components. The movable parts are susceptible to external vibration, and the electronic components distort the distribution of the measured electric field. Therefore, we proposed a novel MEMS electric field sensor based on surface acoustic wave (SAW) technology. The SAW electric field sensor is a delay line device with an interdigital transducer and a reflector. The substrate of the device is a ZnO/SiO2/Si multilayer structure. The ZnO piezoelectric layer is not only used as the propagation medium of SAW, but also used as the sensing film of the external electric field. Then, the external electric field could be detected by analyzing the change of the eigenfrequency of the SAW. The multilayer structure of the substrate was prepared by MEMS process. The interdigital transducer and the reflector are fabricated by the lift-off process. The SAW sensor is characterized at different external electric field strengths by a network analyzer. The sensitivity of the sensor was 0.23 kHz/(kV m−1) and the nonlinearity was 6.8%.
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Yuan, Xiaowei, Zeng Yang, Weijia He, Minglin Yang et Xinqiing Sheng. « A Novel Hybrid Approach for Computing Electromagnetic Scattering from Objects with Honeycomb Structures ». Electronics 12, no 8 (13 avril 2023) : 1851. http://dx.doi.org/10.3390/electronics12081851.
Texte intégralRésumé :
We propose in this paper a novel hybrid numerical modeling method for computing electromagnetic scattering from inhomogeneous targets containing honeycomb structures. In the proposed approach, the whole honeycomb structure is divided into the inner and outer two subregions. Each thin wall of a unit cell in the outer subregion is replaced by a zero-thickness surface, with the aid of a resistive sheet boundary condition (RSBC) to describe the electric and magnetic field discontinuities across the surface. Each unit cell in the inner subregion is homogenized by using the Hashin–Shtrikman and the Mori–Tanaka formulae. The two subregions are further divided into smaller subdomains by introducing the Robin-type transmission condition to couple subregion interfaces, as well as subdomain interfaces. The whole solution region is then discretized and solved using the nonconformal domain decomposition-based hybrid finite element–boundary integral–multilevel fast multipole algorithm (FE-BI-MLFMA). The numerical results demonstrate that the proposed approach exhibits a high accuracy, efficiency, and flexibility. Solutions of scattering by a wing-like object and a practical unmanned aerial vehicle (UAV) model with honeycomb radar-absorbing structures are presented, showing the superior performance of the proposed algorithm.
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Romano, Donato, Akshat Wahi, Marco Miraglia et Cesare Stefanini. « Development of a Novel Underactuated Robotic Fish with Magnetic Transmission System ». Machines 10, no 9 (1 septembre 2022) : 755. http://dx.doi.org/10.3390/machines10090755.
Texte intégralRésumé :
In this study, a robotic fish inspired to carangiform swimmers is developed. The artifact presents a new transmission system that employs the magnetic field interaction of permanent magnets to ensure waterproofness and prevention from any overload for the structure and the actuating motor. This mechanism converts the rotary motion of the motor into oscillatory motion. This oscillating system, along with the wire-driven mechanism of the tail, generates the required traveling wave in the robotic fish. The complete free swimming robotic fish, measuring 179 mm in length with a mass of only 77 g, was able to maintain correct posture and neutral buoyancy in water. Multiple experiments were conducted to test the robotic fish performance. It could swim with a maximal speed of 0.73 body lengths per second (0.13 m/s) at a tail beat frequency of 3.25 Hz and an electric power consumption of 0.67 W. Furthermore, the robotic fish touched the upper bound of the efficient swimming range, expressed by the dimensionless Strouhal number: 0.43 at 1.75 Hz tail beat frequency. The lowest energy to travel 1 meter was 4.73 Joules for the final prototype. Future works will focus on endowing the robot with energy and navigation autonomy, and on testing its potential for real-world applications such as environmental monitoring and animal–robot interaction.
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Fan, Ting-Ting, Hui-Hui Zhang, Yang-Hua Tang, Fan-Zhong Zhang et Bing-Nan Han. « Two New Neo-debromoaplysiatoxins—A Pair of Stereoisomers Exhibiting Potent Kv1.5 Ion Channel Inhibition Activities ». Marine Drugs 17, no 12 (21 novembre 2019) : 652. http://dx.doi.org/10.3390/md17120652.
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A pair of stereoisomers possessing novel structures with 6/6/5 fused-ring systems, neo-debromoaplysiatoxin E (1) and neo-debromoaplysiatoxin F (2), were isolated from the marine cyanobacterium Lyngbya sp. Their structures were elucidated using various spectroscopic techniques including high resolution electrospray ionization mass spectroscopy (HRESIMS) and nuclear magnetic resonance (NMR). The absolute stereochemistry was determined by calculated electronic circular dichroism (ECD) and gauge-independent atomic orbital (GIAO) NMR shift calculation followed by DP4+ analysis. Significantly, this is the first report on aplysiatoxin derivatives with different absolute configurations at C9–C12 (1: 9S, 10R, 11S, 12S; 2: 9R, 10S, 11R, 12R). Compounds 1 and 2 exhibited potent blocking activities against Kv1.5 with IC50 values of 1.22 ± 0.22 μM and 2.85 ± 0.29 μM, respectively.
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Sharif, Abubakar, Yi Yan, Jun Ouyang, Hassan Tariq Chattha, Kamran Arshad, Khaled Assaleh, Abdullah Alhumaidi Alotabi et al. « Uniform Magnetic Field Characteristics Based UHF RFID Tag for Internet of Things Applications ». Electronics 10, no 13 (3 juillet 2021) : 1603. http://dx.doi.org/10.3390/electronics10131603.
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This paper presents a novel inkjet-printed near-field ultra-high-frequency (UHF) radio frequency identification (RFID) tag/sensor design with uniform magnetic field characteristics. The proposed tag is designed using the theory of characteristics mode (TCM). Moreover, the uniformity of current and magnetic field performance is achieved by further optimizing the design using particle swarm optimization (PSO). Compared to traditional electrically small near-field tags, this tag uses the logarithmic spiral as the radiating structure. The benefit of the logarithmic spiral structure lies in its magnetic field receiving area that can be extended to reach a higher reading distance. The combination of TCM and PSO is used to get the uniform magnetic field and desired resonant frequency. Moreover, the PSO was exploited to get a uniform magnetic field in the horizontal plane of the normal phase of the UHF RFID near-field reader antenna. As compared with the frequently-used commercial near field tag (Impinj J41), our design can be readable up to a three times greater read distance. Furthermore, the proposed near-field tag design shows great potential for commercial item-level tagging of expensive jewelry products and sensing applications, such as temperature monitoring of the human body.
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Lal, Deepak Kumar, et Ajit Kumar Barisal. « Grasshopper Algorithm Optimized Fractional Order Fuzzy PID Frequency Controller for Hybrid Power Systems ». Recent Advances in Electrical & ; Electronic Engineering (Formerly Recent Patents on Electrical & ; Electronic Engineering) 12, no 6 (22 novembre 2019) : 519–31. http://dx.doi.org/10.2174/2352096511666180717142058.
Texte intégralRésumé :
Background: Due to the increasing demand for the electrical power and limitations of conventional energy to produce electricity. Methods: Now the Microgrid (MG) system based on alternative energy sources are used to provide electrical energy to fulfill the increasing demand. The power system frequency deviates from its nominal value when the generation differs the load demand. The paper presents, Load Frequency Control (LFC) of a hybrid power structure consisting of a reheat turbine thermal unit, hydropower generation unit and Distributed Generation (DG) resources. Results: The execution of the proposed fractional order Fuzzy proportional-integral-derivative (FO Fuzzy PID) controller is explored by comparing the results with different types of controllers such as PID, fractional order PID (FOPID) and Fuzzy PID controllers. The controller parameters are optimized with a novel application of Grasshopper Optimization Algorithm (GOA). The robustness of the proposed FO Fuzzy PID controller towards different loading, Step Load Perturbations (SLP) and random step change of wind power is tested. Further, the study is extended to an AC microgrid integrated three region thermal power systems. Conclusion: The performed time domain simulations results demonstrate the effectiveness of the proposed FO Fuzzy PID controller and show that it has better performance than that of PID, FOPID and Fuzzy PID controllers. The suggested approach is reached out to the more practical multi-region power system. Thus, the worthiness and adequacy of the proposed technique are verified effectively.
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Hu, Jin Lian, et Harishkumar Narayana. « Novel Behavior in Smart Polymeric Materials : Stress Memory and its Potential Applications ». Advances in Science and Technology 97 (octobre 2016) : 93–99. http://dx.doi.org/10.4028/www.scientific.net/ast.97.93.
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Materials, structures and systems, responsive to an external stimulus are smart and adaptive to our human demands. Among smart materials, polymers with shape memory effect are at the forefront of research leading to comprehensive publications and wide applications. In this paper, we extend the concept of shape memory polymers to stress memory ones, which have been discovered recently. Like shape memory, stress memory represents a phenomenon where the stress in a polymer can be programmed, stored and retrieved reversibly with an external stimulus such as temperature and magnetic field. Stress memory may be mistaken as the recovery stress which was studied quite broadly. Our further investigation also reveals that stress memory is quite different from recovery stress containing multi-components including elastic and viscoelastic forces in addition to possible memory stress. Stress memory could be used into applications such as sensors, pressure garments, massage devices, electronic skins and artificial muscles. The current revelation of stress memory potentials is emanated from an authentic application of memory fibres, films, and foams in the smart compression devices for the management of chronic and therapeutic disorders.
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Sun, Jinji, Jianyi Ren et Haoxi Sun. « A Novel Design of an Inner Rotor for Optimizing the Air-Gap Magnetic Field of Hollow-Cup Motors ». Machines 10, no 5 (27 avril 2022) : 314. http://dx.doi.org/10.3390/machines10050314.
Texte intégralRésumé :
In order to obtain a high power density, spacecraft usually use hollow-cup motors with trapezoidal air-gap magnetic field waveforms. However, due to structural issues, the hollow-cup motor has the problem that the waveform of the air-gap magnetic field is inconsistent with the ideal trapezoidal waveform, which causes torque ripples. In order to reduce torque ripples, the existing method only changes the structure of PMs; the changed PMs are difficult to magnetize and manufacture, which causes the air-gap magnetic field waveform to be unsuitable as the ideal waveform. This paper proposes a novel design of an inner rotor of a hollow-cup motor with an eccentric inner rotor based on the characteristics that the hollow-cup motor has inner and outer rotors and the two rotors rotate synchronously during operation. First, the influencing factors of the air-gap magnetic field are analyzed and the mathematical model of the eccentric inner rotor is established. Then, an eccentric model is established by finite element analysis, which proves that the eccentricity of the inner rotor can make the air-gap magnetic field waveform closer to the ideal trapezoid. Finally, a prototype based on the optimal eccentricity value is developed, verifying the effectiveness of the novel design of the inner rotor.
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Yang, Guangyao, Shengbo Ye, Feng Zhang, Yicai Ji, Xiaojuan Zhang et Guangyou Fang. « Dual-Polarized Dual-Loop Double-Slot Antipodal Tapered Slot Antenna for Ultra-Wideband Radar Applications ». Electronics 10, no 12 (8 juin 2021) : 1377. http://dx.doi.org/10.3390/electronics10121377.
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The miniaturized high-gain antenna is required in portable, ultra-wideband radar systems. However, the miniaturization, ultra-wideband and high gain often restrict each other in the antenna design. In this paper, a dual-polarized, double-slot, antipodal tapered slot antenna with a double-layer, dual-loop structure and novel slot edges is presented. The proposed magnetic dual-loop structure has the capacity to reduce the low cut-off frequency of the double-slot tapered slot antenna by weakening the resonance and coupling. In addition, the high gain, low sidelobe level (SLL), and low cross-polarization level are achieved in the boresight direction. A novel gradient slot profile is designed to improve the low-frequency directivity of the tapered slot antenna without affecting the matching. To feed the antenna elements, a kind of wideband, balun-divider structure is designed. The dual-polarized antenna is combined by two orthogonal elements in a cross configuration without galvanic contact or influence to performance. The measured results show that the impedance bandwidth of the proposed antenna is 0.6~4 GHz, and the maximum gain is 11 dBi. The isolation between the two antenna ports is better than 32 dB, and the cross-polarization discrimination (XPD) is better than 20 dB.
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Yuan, Bin, Qing Du, Chengxiang Hao, Yan Zhao et Zhongjun Yu. « A Novel Wideband Transition from LTCC Laminated Waveguide to Air-Filled Rectangular Waveguide for W-band Applications ». Micromachines 14, no 1 (25 décembre 2022) : 52. http://dx.doi.org/10.3390/mi14010052.
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In this paper, a novel wideband transition from a laminated waveguide (LWG) to an air-filled rectangular waveguide (RWG) is proposed for millimeter-wave integration solutions based on multilayer low-temperature co-fired ceramic (LTCC) technology. The integrated transition cavity is divided into several resonators by introducing five grounded via holes. Due to the magnetic wall existing in the symmetry plane, the equivalent circuit of the proposed transition can be simplified as a three-pole filter model to explain the working mechanism with wideband performance. A W-band integrated LWG-to-RWG transition is designed as an example using LTCC technology. Two back-to-back prototypes with different lengths are fabricated and measured. A measured 25.7% bandwidth from 76 GHz to 101 GHz can be achieved for return loss better than 14 dB. The average insertion loss of a single transition is about 0.5 dB. The compact structure and wideband performance give it potential in high-density millimeter-wave and terahertz packaging.
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Chen, Chao, Tao Lin, Jianteng Niu, Yiming Sun, Liu Yang, Wang Kang et Na Lei. « Surface acoustic wave controlled skyrmion-based synapse devices ». Nanotechnology 33, no 11 (23 décembre 2021) : 115205. http://dx.doi.org/10.1088/1361-6528/ac3f14.
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Abstract Magnetic skyrmions, which are particle-like spin structures, are promising information carriers for neuromorphic computing devices due to their topological stability and nanoscale size. In this work, we propose controlling magnetic skyrmions by electric-field-excited surface acoustic waves in neuromorphic computing device structures. Our micromagnetic simulations show that the number of created skyrmions, which emulates the synaptic weight parameter, increases monotonically with increases in the amplitude of the surface acoustic waves. Additionally, the efficiency of skyrmion creation is investigated systemically with a wide range of magnetic parameters, and the optimal values are presented accordingly. Finally, the functionalities of short-term plasticity and long-term potentiation are demonstrated via skyrmion excitation by a sequence of surface acoustic waves with different intervals. The application of surface acoustic waves in skyrmionic neuromorphic computing devices paves a novel approach to low-power computing systems.
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Corradini, Valentina, Leonardo A. Pajewski, Davide Di Censo, Marcello Alecci et Angelo Galante. « Characterization of a Novel Packaged Hydrogel Wound Dressing by 2.35 T Magnetic Resonance Imaging ». Electronics 12, no 1 (30 décembre 2022) : 188. http://dx.doi.org/10.3390/electronics12010188.
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Hydrogel wound dressing makes easier the treatment of patients suffering from difficult wounds. A new process for the manufacturing of a sterile, packaged hydrogel wound dressing, based on an interpenetrating structure of calcium alginate, agar, and polyvinylpyrrolidone, was recently developed. The new formulation overtakes some previous technologies’ drawbacks expressing a better resistance to mechanical deformations compared to products on the market. In this work, the 2.35 T proton density, spin-lattice relaxation time, spin-spin relaxation time, phase-coherence relaxation, and water apparent diffusion coefficient analysis in the new hydrogel and several alternative formulations, including a commercial one (Neoheal®), are reported. Specifically, the combination of agar, acting as a thermolabile forming agent, with calcium alginate and γ irradiated polyvinylpyrrolidone, acting, respectively, as physical, and chemical crosslinking agents with an irreversible (temperature independent) effect, have been investigated. The new hydrogel formulation brings a qualitative improvement in its handling due to its increased mechanical stiffness when compared to the commercial hydrogel reference. This comes together with a reduced water content (100 vs. 112 for proton density in arbitrary units) and swelling capacity (88% vs. 124%) but with improved water mobility (1.42 vs. 1.34 × 10−3 mm2 s−1 for the apparent diffusion coefficient).
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Wang, Huan, Chun-Juan He, Sheng Xu, Yi-Yan Wang, Xiang-Yu Zeng, Jun-Fa Lin, Xiao-Yan Wang et al. « Single crystal growth of topological semimetals and magnetic topological materials ». Acta Physica Sinica 72, no 3 (2023) : 038101. http://dx.doi.org/10.7498/aps.72.20211961.
Texte intégralRésumé :
Topological materials have attracted much attention due to their novel physical properties. These materials can not only serve as a platform for studying the fundamental physics, but also demonstrate a significant potential application in electronics, and they are studied usually in two ways. One is to constantly explore new experimental phenomena and physical problems in existing topological materials, and the other is to predict and discover new topological material systems and carry out synthesis. In a word, high-quality crystals are very important for studying quantum oscillations, angle resolved photoemission spectra or scanning tunneling microscopy. In this work, the classifications and developments of topological materials, including topological insulators, topological semimetals, and magnetic topological materials, are introduced. As usually employed growth methods in growing topological materials, flux and vapour transport methods are introduced in detail. Other growth methods, such as Bridgman, float-zone, vapour deposition and molecular beam epitaxy methods, are also briefly mentioned. Then the details about the crystal growth of some typical topological materials, including topological insulators/semimetals, high Chern number chiral topological semimetals and magnetic topological materials, are elaborated. Meanwhile, the identification of crystal quality is also briefly introduced, including the analysis of crystal composition and structure, which are greatly important.