Journal articles on the topic 'Locked up electromagnetic forces'
To see the other types of publications on this topic, follow the link: Locked up electromagnetic forces.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Locked up electromagnetic forces.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Teichrib, Sergey, and Richard Krimm. "Electromagnetic Material Feeder for High Speed Rates." Advanced Materials Research 769 (September 2013): 213–20. http://dx.doi.org/10.4028/www.scientific.net/amr.769.213.
Full textAbstract:
In sheet metal forming technology stamping machines are mainly used for an economical production of sheet metal workpieces. Apart from increasing the stroke rates of currently more than 3000 min-1, which can be achieved with modern high-performance stamping machines, the demands on the periphery of the plant are rising as well. In particular, this concerns the material feeding systems used for a reliable feed of the sheet metal. The current technology is based primarily on the roll and gripper feed. Here the sheet metal is clamped between the grippers or rollers with a high contact pressure, which is required for a slip-free operation. To avoid an external damage of the surface or a roll out of the sheet, the clamping forces may not be increased indefinitely. In addition, contamination of the sheet metal or the elements of the feeding system should be excluded in order to avoid a permanent damage of the system and related maintenance costs. This means that the feed rates of previous feeding systems, currently up to 2000 min-1, cannot be further increased, so that the performance potential of modern high-performance presses with large stroke rates cannot be exhausted. Thus the development of feeding systems in sheet metal processing with significantly higher forces is required.As part of a research project at the IFUM, facilitated by the German Machine Tools' Association (VDW), a novel method has been developed in which the sheet metal is fed completely without contact by means of electromagnetic forces. No mechanical elements are required for clamping the sheet metal, so that the inertia of the system can be reduced significantly. Thus higher dynamic properties of the feeder can be realized. The principle is based on the asynchronous linear motor with eddy current runner in a double cam arrangement. This feeder basically consists of two primary components, comprised of a laminated iron package and a three-phase winding. The primaries are symmetrically fixed positioned to compensate the forces of attraction in ferromagnetic materials as well as the repulsive forces in paramagnetic sheet metals such as aluminium or copper. The electrical conductive sheet metal acts as a secondary part and is located in the air gap between the two primary components. Thus the sheet is kept suspended in the air gap a damage to the sheet metal surface is prevented. Therefore surface-finished metal sheets can also be fed with high speed rates. The force initiation is performed entirely contactless to the sheet metal with the three-phase winding in the primaries which induce a sinusoidal magnetic traveling field in the air gap. During operation eddy currents are induced in the metal strip due to the speed of the traveling magnetic field relative to the sheet. By the interaction between the magnetic field and the eddy currents an advancing force is applied to the sheet metal according to the Lorentz law.For the design and optimization of the electromagnetic feeder extensive simulation-based studies have been performed using a parameterized finite element model. For this purpose the development of a three-dimensional model was necessary to represent the eddy currents in the sheet metal. The main subjects of the investigations were in particular the optimization of the iron core, the winding distribution and also to ensure an acceptable temperature in the primaries and the sheet metal during continuous operation. The studies show that, depending on the sheet material applied, very high feed forces can be achieved. For sheet metals with a width of about 100 mm more than 1000 N can be achieved by means of the electromagnetic feeding system. Compared to current mechanical feeders the forces can be more than doubled.To validate the simulation results and test the functional ability a demonstrator of the electromagnetic feeder was designed and manufactured. Due to the simulation-based optimization of the feeding system an external cooling is not required. The control of the feeder is realised via a conventional frequency converter, with which the voltage can be controlled in its amplitude and frequency, and thus indirectly the sheet metal position. The first experimental investigations were carried out on a specially designed force test bench. The results show a very good correlation obtained by simulation and the experimental measured feed forces. Future work objectives are to identify the feed characteristics and limitations as well as the implementation of a robust control algorithm for a reliable positioning of the sheet metal.
2
Zeng, Chong, Song Huang, Yongming Yang, and Guanghou Zhou. "Influence of End Structure on Electromagnetic Forces on End Winding of a 1550 MW Nuclear Generator." International Journal of Rotating Machinery 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/9545238.
Full textAbstract:
A 3D electromagnetic model of the end region of a 1550 MW nuclear generator is set up. The electromagnetic forces on the involute and nose parts of the end winding under a rated operation are obtained through the 3D time-step finite element method. The electromagnetic forces on different coils in the same phase are analyzed. By changing the rotor’s relative length and stator coil’s linear length in the 3D electromagnetic model, the electromagnetic force distributions on the end winding are obtained. The influence of each structure change on the electromagnetic force in different directions is studied in detail. Conclusions that can be helpful in decreasing the electromagnetic forces on the end winding through optimizing the end region design are presented.
3
Cheesewright, R., and C. Clark. "The Influence of Forces Due to Electromagnetic Pick-Ups on the Performance of Small Turbine Flowmeters." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 210, no. 4 (November 1996): 243–47. http://dx.doi.org/10.1243/pime_proc_1996_210_463_02.
Full textAbstract:
An analysis is presented of the influence of forces due to an electromagnetic pick-up on the calibration of small turbine flowmeters. The analysis shows how the forces can produce high starting flows. A comparison between the theory and the experimental results of calibrating a meter both with and without the electromagnetic pick-up suggests that the dominant effect of the pick-up is to produce an additional resisting torque which is almost independent of the rotational speed of the meter.
4
Suzuki, Nobuhisa, Toshiaki Murakami, Junichi Shibuya, Yasuhiro Furukawa, Satoru Asai, and Shizuo Ohshima. "Structural Component Development of Three-Layer Cylinders for Superconducting Generators, Part 2: Development of Three-Layer Welding Techniques to Extend Axial Length and Evaluation of the Welds." Journal of Manufacturing Science and Engineering 119, no. 1 (February 1, 1997): 78–87. http://dx.doi.org/10.1115/1.2836558.
Full textAbstract:
The warm damper is one of the multi-cylindrical rotor components, which is located at the outermost position in a rotor of the superconducting generator. The main function of the warm damper, in addition to bear rotor torque, is to shut off the magnetic fields of the armature. While maximum stresses in the warm damper are caused by electromagnetic forces in the event of a short-circuit fault, which cause large bending stresses, so it is required to have high conductivity and sufficient strength against bending stresses. A promising design for it is a three-layer cylindrical structure composed of a highly conductive Cu-Cr cylinder sandwiched between inner and outer stiffeners made of a high-strength nonmagnetic material (A286). To realize this structure, it is necessary first to select a suitable layer bonding method and then to research and develop the procedures to construct this large structure. The previous paper described selection of diffusion bonding as the suitable layer bonding method. The first step to fabricate this large structure was to prove the structural integrity of a diffusion-bonded mock-up model, which was 885 mm in diameter and 2800 mm in axial length [1]. This paper is a study on circumferential three-layer welding to extend the axial length allowing for the fabrication of a ever larger structure. Two A286/Cu-Cr/A286 three-layer rings, 625.5 mm in O.D. and 300 mm in axial length, were prepared by diffusion bonding the layers of each rings simultaneously by HIP. Then, the axial ends of their three-layers were butt welded with the filler wires, which were selected for each layers in advance. Subsequently, in accordance with the results of a study on the condition for aging treatment following diffusion bonding (800°C × 4 h) to obtain the proper mechanical properties of the alloy A286, which is a material for the major load bearing component, the rings were age-treated at 700°C for 10 h. The tensile test results of the welded joint and weld metal specimens cut out from the welded rings proved that both alloys A286 and Cu-Cr welded components had adequate mechanical properties. That is these properties were equivalent to those of the base metals, with no reductions of layer bonding strength due to weld heat input.
5
Calabrese, Allegra, Djamal Gacemi, Mathieu Jeannin, Stéphan Suffit, Angela Vasanelli, Carlo Sirtori, and Yanko Todorov. "Coulomb forces in THz electromechanical meta-atoms." Nanophotonics 8, no. 12 (October 25, 2019): 2269–77. http://dx.doi.org/10.1515/nanoph-2019-0314.
Full textAbstract:
AbstractThanks to their large sensitivity to electromagnetic fields, microelectromechanical systems are becoming attractive for applications in the THz band (0.1–10 THz). However, up to date all THz electromechanical systems couple electromagnetic fields to mechanical motion only through photothermal dissipative forces: such mechanism allows for sensitive detection but prevents applications that require coherent transfer of information. In this work, we present a THz electromechanical meta-atom where the coupling between an electromagnetic mode and the displacement of a metallic micro-beam is substantially controlled by a conservative Coulomb force due to charge oscillations in the nanometric-size capacitive part of the meta-atom. We present experiments, performed at room temperature, which allow distinguishing and precisely quantifying the contributions of conservative and dissipative forces in the operation of our electromechanical resonator. Our analysis shows that the Coulomb force becomes the dominant contribution of the total driving force for high-order mechanical modes. Such system paves the way for the realization of coherent THz to optical transducers and allows the realization of fundamental optomechanical systems in the THz frequency range.
6
Galin, Mikhail A., Vladimir M. Krasnov, Ilya A. Shereshevsky, Nadezhda K. Vdovicheva, and Vladislav V. Kurin. "Coherent amplification of radiation from two phase-locked Josephson junction arrays." Beilstein Journal of Nanotechnology 13 (December 6, 2022): 1445–57. http://dx.doi.org/10.3762/bjnano.13.119.
Full textAbstract:
We analyze experimentally and theoretically mutual phase locking and electromagnetic interaction between two linear arrays with a large number of Josephson junctions. Arrays with different separation, either on the same chip or on two separate substrates are studied. We observe a large coherent gain, up to a factor of three, of emitted power from two simultaneously biased arrays, compared to the sum of powers from two individually biased arrays. The phenomenon is attributed to the phase locking of junctions in different arrays via a common electromagnetic field. Remarkably, the gain can exceed the factor of two expected for a simple constructive interference of two oscillators. The larger gain is explained by an additional consequence of mutual interaction between two large arrays. Mutual phase locking of large arrays does not only result in constructive interference outside the arrays, but also improved synchronization of junctions inside each array. Our conclusion is supported by numerical modelling.
7
Wilson, James H. "The quantum electrodynamics physical (QED-P) theory to complement quantum electrodynamics (QED)." Physics Essays 34, no. 1 (March 21, 2021): 17–27. http://dx.doi.org/10.4006/0836-1398-34.1.17.
Full textAbstract:
The electronic and muonic hydrogen energy levels are calculated very accurately [M. L. Eides, H. Grotch, and V. Shelyuto, Phys. Rep. 342, 63 (2001)] in Quantum Electrodynamics (QED) by coupling the Dirac Equation four vector c(α, I) current covariantly with the external electromagnetic (EM) field four vector in QED’s Interactive Representation. While QED has been extraordinarily successful computationally, it presents no physical description of the electron, or other charged leptons. The QED-Physical (QED-P) theory presented in this paper is equivalent to QED in that it is based only on the four-current c(α, I) that is the reason that QED is so accurate computationally. However, QED-P describes the electron geometrically through the internal time/coordinate operators derived directly from c(α, I) with no assumptions. QED-P’s internal coordinate operators define an electron Center of Charge (CoC) point vibrating rapidly in space and time in its unique vacuum, creating the current that produces the electron’s magnetic moment and spin, and eliminating the need for “intrinsic” properties. QED-P also cuts off the photon propagator in a natural way so that the electron self-energy is finite and ad hoc renormalization procedures are not necessary. The c α-Non Exclusion Principle states that, if QED accepts c(α, I) as the electron current operator because of the very accurate hydrogen energy levels calculated, then one must also accept the QED-P electron internal spatial and time coordinate operators (ISaTCO) derived directly from c(α, I) without any other assumptions. QED-P shows the electron to be in both spin states simultaneously, and it is the external EM field that forces the electron’s spin state to be measured up or down. QED-P describes the bizarre, and very different, situation illustrated in Fig. 1 when the electron and muon are located “inside” the spatially extended proton with their CoCs orbiting the proton at the speed of light in S energy states of hydrogen, shedding some insight into the proton radius puzzle. The electron only appears to be a point particle with intrinsic properties when observed/measured from the far field. The Dirac‐Maxwell‐Wilson Equations are derived directly from the electron ISaTCO, and its EM fields “look” like they are from a point particle in far field scattering experiments in the same way the electric field from a sphere with evenly distributed charge “e” looks like a point charge with the same charge in the far field (Gauss Law). A physical basis for Quantum Entanglement is derived that can be measured experimentally.
8
Kari, Tusong Jiang, Xi Wang Abuduwayiti, and Ming Ma. "Numerical Calculation of Short Circuit Electromagnetic Force in Isolated Phase Bus." Advanced Materials Research 986-987 (July 2014): 944–47. http://dx.doi.org/10.4028/www.scientific.net/amr.986-987.944.
Full textAbstract:
Short circuit electromagnetic forces are one of the most important factors in design and operation of buses. 2D infinite element models are set up with ANSOFT for isolated phase buses, simulating with transient method and calculating short circuit electromagnetic force taking eddy effect and proximity effect into account. The result reveals that the maximum electromagnetic force under short circuit condition is a periodic function of current phase angle.
9
Böyük, Mustafa, Yakup Eroğlu, Günyaz Ablay, and Kutay İçöz. "Feedback controller designs for an electromagnetic micromanipulator." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 234, no. 6 (September 9, 2019): 759–72. http://dx.doi.org/10.1177/0959651819871783.
Full textAbstract:
Magnetic micromanipulators are capable of generating wide range of magnetic forces to manipulate magnetic microparticles for biomedical applications. In this study, a multipole magnetic micromanipulator system including electromagnets, driver circuitry and control unit is designed, modeled and implemented. The micromanipulator can produce a broad range of magnetic forces up to 25 pN on a single magnetic microparticle (1–10 µm diameter) that is 5 mm away from the electromagnet core tip. Both linear and nonlinear controllers are designed and implemented, and the proposed nonlinear controller produces smooth control currents to assure closed-loop stability of the system with 1 s non-overshoot transient response and zero steady-state tracking error. The maximum output current of the driver circuitry is set to 1 A. The single particle at the center is moved at a speed of 5 mm/s. The fully automatic system can be utilized in applications related to single cell or microparticle manipulations.
10
Lu, H., C. Wang, and Yu M. Zabolotnov. "Using Sliding Mode Control to Set Up a Rotating Electrodynamic Space Tether System." Herald of the Bauman Moscow State Technical University. Series Mechanical Engineering, no. 2 (141) (June 2022): 4–19. http://dx.doi.org/10.18698/0236-3941-2022-2-4-19.
Full textAbstract:
The paper considers the process of imparting rotation at a given angular velocity to an electrodynamic space tether system in a near-Earth orbit. The tether system is a linear cluster of three microsatellites connected by insulated conductive cables. Initially the system is gravitationally stabilised in the approximate vertical direction. Electromagnetic forces generated in the conductive cables by the geomagnetic field impart rotation to the system. We stated the equations of motion for the system in the Earth-fixed coordinate system, taking into account distributed load produced by gravitational and electromagnetic forces. The system is moving in a fairly high, almost circular orbit, so aerodynamic forces are not taken into account. Adjusting the current will reduce the strain in the tethers. The model under consideration represents those as a set of material points connected by unilateral elastic links. We propose a feedback current controller based on sliding mode control. The system variables lie on a single surface, moving across which ensures asymptotic stability of the control process. We used a simplified system motion model to synthesise the controller parameters. We analysed the angular motion of microsatellites with respect to the tether direction while rotation is imparted to the system. Numerical examples confirm the efficiency of our approach to setting up a rotating space tether system
11
Alcocer, Giovanni. "Mass & Quark Symmetry: Mass and Mass Cloud (The Yin Yang): Atom Binding Energy; Molecules Binding Energy; Binding energy between the nucleons in the nucleus; Particle Interaction Energy between particle and antiparticle; Quark Symmetry & Quark Confinement." Mediterranean Journal of Basic and Applied Sciences 06, no. 03 (2022): 01–34. http://dx.doi.org/10.46382/mjbas.2022.6301.
Full textAbstract:
The symmetry occurs in most of the phenomena explained by physics, for example, a particle has positive or negative charges, and the electric dipoles that have the charge (+q) and (-q) which are at a certain distance (d), north or south magnetic poles and for a magnetic bar or magnetic compass with two poles: North (N) and South (S) poles, spins up or down of the electron at the atom and for the nucleons in the nucleus In this form, the particle should also have mass symmetry. For convenience and due to later explanations, I call this mass symmetry or mass duality as follows: mass and mass cloud. The mass cloud is located in the respective orbitals given by the Schrödinger equation. The orbitals represent the possible locations or places of the particle which are determined probabilistically by the respective Schröndiger equation. For example and for the proton, the positive charge is concentrated in its mass nucleus with an uncharged mass cloud around its nucleus distributed in the orbitals or mass clouds. For the electron, the negative charge is concentrated in its mass nucleus with an uncharged mass cloud around its nucleus distributed in the orbitals or mass clouds. Besides, in the formation of the hydrogen atom, a part of the mass cloud of the proton interacts with the mass cloud of the electron, and the total mass-energy lost in this interaction is transformed into electromagnetic energy according to Einstein's equation: E=mc2 and the variant mass formula discovered and developed by myself: Giovanni Alcocer Variant Formulas. Therefore, the electron and proton are bound together in the hydrogen atom due to the electrostatic force between the two particles and the mass cloud of the electron and proton with some mass cloud lost in the interaction and converted to electromagnetic energy or photons. Then, it is right to assume this mass symmetry, since the electron and the proton in the interaction of the mass cloud lose mass but do not lose electric charge. In this form, it is justified the existence of a mass cloud. Therefore, the main function of the mass cloud is the binding energy. The mass cloud interaction generates binding energy between the electrons and the nucleus in the atom through the protons and between the nucleons in the nucleus: protons with protons, neutrons with neutrons, and protons with neutrons. The nuclear force between two nucleons is characterized by being strong and short-range. Also, it can be justified by the existence of the mass cloud: the mass clouds of nucleons within the nucleus interact with each other without any effect on the proton charge. In the same form and due to the quarks having mass and charge (and inclusive colors), the quarks have also the same mass symmetry: mass and mass cloud. Thus, the electrical charge is stored in the mass of the quarks and the mass cloud allows the confinement or the respective binding between quarks. Then, the following questions are explained and answered simply in this research article: why a particle does not exist with only one quark? why the quarks are confined to the nucleus? and which is the origin of the nuclear forces? On other hand, there are particles with two quarks (mesons), particles with three quarks (baryons) and then, it is very probable to find particles with more than three quarks (quaternions). This scientific research presents evidence of the existence of mass symmetry: mass and mass cloud and the interaction between the mass cloud of the particles (The Yin Yang Interaction) based on Einstein's equation and in the Variant Mass formula for the Electron in the atom discovered and demonstrated by myself where experimental results are detailed.
12
Nilsson, Johnny E., and Hans G. Rosdahl. "Contribution of Leg-Muscle Forces to Paddle Force and Kayak Speed During Maximal-Effort Flat-Water Paddling." International Journal of Sports Physiology and Performance 11, no. 1 (January 2016): 22–27. http://dx.doi.org/10.1123/ijspp.2014-0030.
Full textAbstract:
The purpose was to investigate the contribution of leg-muscle-generated forces to paddle force and kayak speed during maximaleffort flat-water paddling. Five elite male kayakers at national and international level participated. The participants warmed up at progressively increasing speeds and then performed a maximal-effort, nonrestricted paddling sequence. This was followed after 5 min rest by a maximal-effort paddling sequence with the leg action restricted—the knee joints “locked.” Left- and rightside foot-bar and paddle forces were recorded with specially designed force devices. In addition, knee angular displacement of the right and left knees was recorded with electrogoniometric technique, and the kayak speed was calculated from GPS signals sampled at 5 Hz. The results showed that reduction in both push and pull foot-bar forces resulted in a reduction of 21% and 16% in mean paddle-stroke force and mean kayak speed, respectively. Thus, the contribution of foot-bar force from lower-limb action significantly contributes to kayakers’ paddling performance.
13
Szántó, Attila, János Kiss, Tamás Mankovits, and Gusztáv Áron Szíki. "Dynamic Test Measurements and Simulation on a Series Wound DC Motor." Applied Sciences 11, no. 10 (May 17, 2021): 4542. http://dx.doi.org/10.3390/app11104542.
Full textAbstract:
Previously, a dynamic model and a simulation program for series wound DC motors (SWDCM) were developed in MATLAB/Simulink for modelling them in electric vehicles and mechatronic systems. The electromagnetic characteristics of the motor (electric resistances, dynamic inductances), which serve as input parameters of the program, were also measured. Additionally, locked rotor response measurements were performed to test the accuracy of the measured electromagnetic characteristics. This paper presents the experimental procedure and the results of dynamics test measurements that were performed on the same motor, including the procedure for the determination of the necessary input dynamic parameters for the simulation. While the motor spins up from rest, the intensity of the electric current and the angular speed of the rotor are measured. Finally, the simulation and dynamic test results are compared to check the proper operation of the simulation program.
14
Smith, Ray T., Fred P. M. Jjunju, Iain S. Young, Stephen Taylor, and Simon Maher. "A physical model for low-frequency electromagnetic induction in the near field based on direct interaction between transmitter and receiver electrons." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 472, no. 2191 (July 2016): 20160338. http://dx.doi.org/10.1098/rspa.2016.0338.
Full textAbstract:
A physical model of electromagnetic induction is developed which relates directly the forces between electrons in the transmitter and receiver windings of concentric coaxial finite coils in the near-field region. By applying the principle of superposition, the contributions from accelerating electrons in successive current loops are summed, allowing the peak-induced voltage in the receiver to be accurately predicted. Results show good agreement between theory and experiment for various receivers of different radii up to five times that of the transmitter. The limitations of the linear theory of electromagnetic induction are discussed in terms of the non-uniform current distribution caused by the skin effect. In particular, the explanation in terms of electromagnetic energy and Poynting’s theorem is contrasted with a more direct explanation based on variable filament induction across the conductor cross section. As the direct physical model developed herein deals only with forces between discrete current elements, it can be readily adapted to suit different coil geometries and is widely applicable in various fields of research such as near-field communications, antenna design, wireless power transfer, sensor applications and beyond.
15
Hamilton, Douglas P., Eberhard Grün, and Michael Baguhl. "Electromagnetic Escape of Dust from the Solar System." International Astronomical Union Colloquium 150 (1996): 31–34. http://dx.doi.org/10.1017/s0252921100501225.
Full textAbstract:
AbstractCollisions of asteroids and among Zodiacal cloud particles produce large amounts of submicron-sized debris, much of which is immediately ejected from our solar system by electromagnetic forces. We investigate the trajectories of tiny grains started on circular uninclined orbits within the Zodiacal cloud and find that they reach high ecliptic latitudes during the current configuration of the solar magnetic.field, perhaps accounting for particles detected by the Ulysses spacecraft at latitudes up to 80°. When the solar magnetic field is reversed, particles are more strongly confined to the ecliptic plane and escape the solar system less readily. Both fluxes and spatial densities of sub-micron sized Zodiacal dust particles vary with time through the dependence of orbital dynamics on the 22-year solar cycle.
16
Domracheva, Yulia, and Sergey Loginov. "Simulation Technique of Synchronous Reluctance Bearingless Machine." Environment. Technology. Resources. Proceedings of the International Scientific and Practical Conference 2 (August 8, 2015): 101. http://dx.doi.org/10.17770/etr2013vol2.845.
Full textAbstract:
Magnetically levitated rotor electric machines can be used under such conditions wherein application of conventional bearings is impossible because of presence of lubrication. Active magnetic bearings application requires rotor length increase and stalling speed is decreased. Bearingless electric machines are the next step up of the magnetically levitated rotor machines. A bearingless electric machine module generates electromagnetic torque and radial forces. This feature makes possible to decrease the rotor length on retention of capacity of torque and forces. It is necessary to verify a control system operation algorithm via simulation model owing to complexity of machine electromagnetic interaction. It is practical to use a variable attribute set model for this purpose. The following article considers one of these models for researching the system via MATLAB Simulink. Basic relations for programmatic model creation are presented. Comparative assessment of various machine model types is made.
17
Ginis, Vincent, and Philippe Tassin. "Transformation optics beyond the manipulation of light trajectories." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 373, no. 2049 (August 28, 2015): 20140361. http://dx.doi.org/10.1098/rsta.2014.0361.
Full textAbstract:
Since its inception in 2006, transformation optics has become an established tool to understand and design electromagnetic systems. It provides a geometrical perspective into the properties of light waves without the need for a ray approximation. Most studies have focused on modifying the trajectories of light rays, e.g. beam benders, lenses, invisibility cloaks, etc. In this contribution, we explore transformation optics beyond the manipulation of light trajectories. With a few well-chosen examples, we demonstrate that transformation optics can be used to manipulate electromagnetic fields up to an unprecedented level. In the first example, we introduce an electromagnetic cavity that allows for deep subwavelength confinement of light. The cavity is designed with transformation optics even though the concept of trajectory ceases to have any meaning in a structure as small as this cavity. In the second example, we show that the properties of Cherenkov light emitted in a transformation-optical material can be understood and modified from simple geometric considerations. Finally, we show that optical forces—a quadratic function of the fields—follow the rules of transformation optics too. By applying a folded coordinate transformation to a pair of waveguides, optical forces can be enhanced just as if the waveguides were closer together. With these examples, we open up an entirely new spectrum of devices that can be conceived using transformation optics.
18
Betts, Reginald Dwayne, and Lori Gruen. "Are Prisons Permissible?" Philosophical Topics 49, no. 1 (2021): 81–97. http://dx.doi.org/10.5840/philtopics20214916.
Full textAbstract:
Class, race, and tough-on-crime political platforms are three of the most discussed, and thus most visible, forces that contribute to mass incarceration. The analysis of each of these forces has been illuminating, yet these broad narratives tend to obscure the burden of prison for those locked up within them. The social narratives that have developed to help understand the prison industrial system often inadvertently obscure the complex experiences and losses endured by prisoners. The psychic and physical toll that accrues from decades of social exile, the affronts to dignity that “corrections” regularly impose, and the injuries to one’s sense of themselves and their relationships that prison foments haven’t received the attention they deserve. This essay explores the question of the permissibility of causing harm through imprisonment and social abandonment, arguing that any adequate answer must make the particular experiences and actual concerns of incarcerated people socially visible.
19
Doerger, Stanley, and Cindy Harnett. "Force-Amplified Soft Electromagnetic Actuators." Actuators 7, no. 4 (October 31, 2018): 76. http://dx.doi.org/10.3390/act7040076.
Full textAbstract:
Electrically-driven direct current (DC) motors are the core component of conventional robots thanks to the ease of computer control and high torque for their size. However, DC motors are often manually attached and soldered into robotic assemblies, and they are not flexible. For soft robotics, researchers have looked to new, compliant materials that are compatible with 3-D printing or other automated assembly methods. In this work we use a computer-controlled embroidery machine to create flat motor windings in flexible fabrics. We model their electromagnetic fields and present them as linear actuators that move a permanent magnet attached to a cable. The fabrication method puts some constraints on the coil design, which are discussed. However, the planar nature of the embroidered sheets enables the designer to use laminar fabrication methods, such as stacking or layering into parts, during 3-D printing. The soft motor windings produced static holding forces of up to 0.25 N and could lift a 0.3 g mass several cm using direct drive. A 3-D printed mechanical amplifier with two stages was able to quadruple the lifting mass, reducing the travel by a factor of 4. Machine embroidery-installed cables and motor coils could lead to “bolts and nuts free” fabrication of thin, electrically-driven cable actuators.
20
YAREMKO, YURIJ. "INTERFERENCE OF OUTGOING ELECTROMAGNETIC WAVES GENERATED BY TWO POINT-LIKE SOURCES." International Journal of Modern Physics A 20, no. 01 (January 10, 2005): 129–59. http://dx.doi.org/10.1142/s0217751x05019804.
Full textAbstract:
An energy–momentum carried by electromagnetic field produced by two point-like charged particles is calculated. Integration region considered in the evaluation of the bound and emitted quantities produced by all points of world-lines up to the end points at which particles' trajectories puncture an observation hyperplane y0=t. Radiative part of the energy–momentum contains, apart from usual integrals of Larmor terms, also the sum of work done by Lorentz forces of point-like charges acting on one another. Therefore, the combination of wave motions (retarded Liénard–Wiechert solutions) leads to the interaction between the sources.
21
Wagner, Norman, and Alexander Scheuermann. "On the relationship between matric potential and dielectric properties of organic free soils: a sensitivity study." Canadian Geotechnical Journal 46, no. 10 (October 2009): 1202–15. http://dx.doi.org/10.1139/t09-055.
Full textAbstract:
High-frequency electromagnetic determination of moisture in porous media, (e.g., soil) is based on the strong relationship between volumetric water content and relative dielectric permittivity. In particular, in fine-grained soils the movement of water is influenced by different surface-bonding forces due to interface processes. The interface effects lead to a number of dielectric relaxation processes (free- and bound-water phase, Maxwell–Wagner effect, counterion relaxation effects). These relaxation processes are the reason for the strong frequency dependence of the electromagnetic material properties below 1 GHz. The matric potential is a measure of the bonding forces on water in the soil. Based on a thermodynamic relationship between soil matric potential and dielectric relaxation behaviour of water in different binding states, a broadband dielectric relaxation model was developed that considers low-frequency dispersion up to 1 MHz as well as losses due to direct-current conductivity. The sensitivity of the model on soil suction was systematically analyzed based on a pedotransfer function (PTF) for soil textures ranging from pure sand up to pure clay. The results are compared with known empirical and semiempirical calibration functions, as well as theoretical mixing models.
22
Clappier, Marcel, and Lothar Gaul. "FE-BE computation of electromagnetic noise of a permanent-magnetic excited synchronous ma-chine considering dynamic rotor eccentricity." MATEC Web of Conferences 211 (2018): 18005. http://dx.doi.org/10.1051/matecconf/201821118005.
Full textAbstract:
Electromagnetic noise in Electrical Machines (EMs) occurs due to vibrations caused by magnetic forces acting onto rotor and stator surface. This is the dominant source for the considered permanent-magnetic excited synchronous machine in this paper. The radiated electromagnetic noise is sequentially calculated by a Finite Element (FE) and Boundary Element (BE) computation. An electromagnetic FE model is created to determine magnetic forces. Structure-borne sound and rotor dynamics are calculated using a structural dynamic FE model for the EM housing and the rotor. In order to predict resonance frequencies and amplitudes as reliable as possible, it is important to know the direction-dependent stiffness of the laminated rotor stacks and mechanical joints as well as their structural damping. Thereby, the properties of the laminated stack can be determined experimentally by a shear and dilatation test. Mechanical joint properties can be modelled by Thin-Layer Elements (TLEs) and the overall damping by the model of constant hysteretic damping. The radiated sound power is determined by a direct BE computation. The influence of dynamic rotor eccentricity on radiated sound power is examined for a run-up of the EM. All FE models are verified by data from experimental modal analysis.
23
Yang, Minghong, Lingxi Xiong, Qinyou Li, Shu Cheng, Yongxin Ye, Zhixiong Liu, Wenbin Hu, and Donglai Guo. "van der Waals forces enhanced light–graphene interaction in optical microfiber polarizer." AIP Advances 12, no. 4 (April 1, 2022): 045027. http://dx.doi.org/10.1063/5.0087857.
Full textAbstract:
A facile and efficient approach to manufacturing optical devices with a plane graphene-coupled microfiber structure is proposed—attaching the optical microfiber onto a monolayer graphene-coated polydimethylsiloxane substrate. Such devices exhibit strong light–graphene interaction via the evanescent fields of the guided light in microfibers and show evident optical polarization and polarization-dependent saturable absorption effect. When the monolayer graphene with propagation distance is 2.5 mm, and the microfiber diameter is 3.9 μm, the polarization extinction ratio can reach up to 31.0 dB with the light wavelength at 1550 nm. The transmission in TM modes could be increased continuously by increasing the input power of light at 980 nm. The transmission with 3 and 10 dB modulation depths in TM modes could be achieved via 980 nm pump power of 15.1 and 66.1 mW, respectively, which is advantageous over unpolarized graphene-coupled microfiber devices. The proposed microfiber on graphene structure could efficiently integrate optical waveguides with two-dimensional materials, with great potential applications in optical polarizers, all-optical modulators, mode-locked fiber lasers, and sensors, especially for all-fiber systems.
24
Matsumoto, S., Seyong Choi, T. Kiyoshi, A. Otsuka, M. Hamada, H. Maeda, Y. Yanagisawa, H. Nakagome, and H. Suematsu. "REBCO Layer-Wound Coil Tests Under Electromagnetic Forces in an External Magnetic Field of up to 17.2 T." IEEE Transactions on Applied Superconductivity 22, no. 3 (June 2012): 9501604. http://dx.doi.org/10.1109/tasc.2012.2185024.
Full text
25
Molavi, Reza, Hormoz Djahanshahi, Rod Zavari, and Shahriar Mirabbasi. "Low-Jitter 0.1-to-5.8 GHz Clock Synthesizer for Area-Efficient Per-Port Integration." Journal of Electrical and Computer Engineering 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/364982.
Full textAbstract:
Phase-locked loops (PLLs) employing LC-based voltage-controlled oscillators (LC VCOs) are attractive in low-jitter multigigahertz applications. However, inductors occupy large silicon area, and moreover dense integration of multiple LC VCOs presents the challenge of electromagnetic coupling amongst them, which can compromise their superior jitter performance. This paper presents an analytical model to study the effect of coupling between adjacent LC VCOs when operating in a plesiochronous manner. Based on this study, a low-jitter highly packable clock synthesizer unit (CSU) supporting a continuous (gapless) frequency range up to 5.8 GHz is designed and implemented in a 65 nm digital CMOS process. Measurement results are presented for densely integrated CSUs within a multirate multiprotocol system-on-chip PHY device.
26
Siljander, Matthew, Denise Koueiter, Sapan Gandhi, Brett Wiater, and Patrick Wiater. "Outcomes Following Low-Profile Mesh Plate Osteosynthesis of Patella Fractures." Journal of Knee Surgery 31, no. 09 (January 30, 2018): 919–26. http://dx.doi.org/10.1055/s-0038-1625958.
Full textAbstract:
AbstractTreatment of patella fractures is fraught with complications and historically poor functional outcomes. A fixation method that allows for early mobilization and decreases symptomatic hardware rates will improve knee range of motion, postoperative functional status, and reoperation rates. The purpose of this study was to evaluate the functional outcomes after locked plate osteosynthesis of patella fractures at a Level 1 trauma center. A retrospective case series was conducted of patients who underwent open reduction internal fixation (ORIF) of a patella fracture using a locked mesh plating technique coupled with neutralization of forces on the distal pole of the patella. Twelve patients were evaluated at a mean follow-up of 19 months (range, 6–30) with physical exam, functional outcomes, and radiographs. There were 9 women and 3 men with an average age of 66.1 years (range, 53–75). Radiographic bony union was achieved in all patients by 3-month follow-up. Visual Analog Pain Score averaged 1.7 (median, 1.0; range, 0–8), the mean Knee Outcome Score – Activities of Daily Living Scale was 83.9 (median, 92.1; range, 45.7–100.0), the mean Short Form Musculoskeletal Function Assessment (SMFA) Function Index was 9.9 (median, 3.7; range, 0.7–41.2), and the mean SMFA Bother Index was 11.1 (median, 3.1; range, 0–62.5). The SF-36 Physical Component Score mean was 48.4 ± 8.5 and the SF-36 Mental Component Score mean was 54.1 ± 9.6. No complications developed and there were no reoperations for nonunion, infection, or symptomatic hardware. This study demonstrates that locked plate osteosynthesis for operative patella fractures can reliably achieve bony union with potentially superior functional outcomes as compared with traditional methods. Further studies are needed to evaluate plate fixation for patella fractures, but early results are promising.
27
Smith, Ray T., Stephen Taylor, and Simon Maher. "Modelling electromagnetic induction via accelerated electron motion." Canadian Journal of Physics 93, no. 7 (July 2015): 802–6. http://dx.doi.org/10.1139/cjp-2014-0366.
Full textAbstract:
The two forms of electromagnetic induction are generally referred to as motional and transformer induction, and although these phenomena have been observed and discussed for well over 150 years, certain aspects remain controversial in the scientific literature. It is well-known that an electromotive force (emf) is induced in a loop of wire encircling a long solenoid carrying alternating current. This is true however even in a region in which there is a negligibly small magnetic or electric field. Although the flux linking concept can explain the induced emf, more recent explanations utilise the concept of vector potential as the causal explanation of induction. In this present investigation, we propose that Weber’s force, based on inter-particle forces, provides a more fundamental explanation. The induced emf is measured directly across a closely wound, 1000 turn narrow coil encircling a long solenoid carrying alternating current. Weber’s force formula has been adapted to the case of transformer induction by treating the solenoid as a stack of current loops and applying the principle of superposition. Analytical calculation is also included for the application of Faraday’s law. Close agreement with experimentally measured values is demonstrated in all cases for low-frequency induction up to around 5 kHz.
28
Guzii, Sergii G., Oleksiy Khodakovskyy, Artem Kovalchuk, Stella Gornostal, and Mariia Maksymova. "Investigation of the Rheological Properties of Liquid Geocement Composite Materials for Protection from Electromagnetic Fields." Solid State Phenomena 338 (October 28, 2022): 161–66. http://dx.doi.org/10.4028/p-2gca7f.
Full textAbstract:
The article presents the results of studies of the rheological properties of liquid geocement composite materials for protection against electromagnetic fields. It has been established that an increase in the concentration of a mixture of functional iron-containing fillers from 15 to 60 wt. % in the speed range from 0.1 to 1 rpm contributes to an increase in dynamic viscosity values from 100,000 to 550,000 cP. It’s noted that with an increase in the spindle speed from 15 to 35 RPM, the values of dynamic viscosity lie in the range of 8860-3442 cP. With the same concentration changes, the plastic viscosity of the liquid composite material in the speed ranges from 10 to 25 rpm changes, respectively, to 1064.5 cP, 3096 cP, 25462 cP, which is 1.04, 3, 03 and 24.9 times exceeds the value of the plastic viscosity of the original geocement paint. It is shown that at low shear rates from 0.02 to 0.3 l/s and an increase in the concentration of the filler mixture from 0 to 60 wt. % shear forces increase sharply on average from 21.2 to 252 dynes/cm2. Increase in shear rate from 0.315 to 7.35 1/s. Shear forces gradually increase from 76 to 252 dynes/cm2. It is shown that when the content of a functional filler with a concentration of 15% liquid composite material can be applied to the substrate by pneumatic spraying; with a concentration of 30% - with a brush or roller; with a concentration of 45 to 60% using a spatula. The total shielding coefficients of the electromagnetic field of industrial frequency by layers of a mixture with a thickness of 0.22-0.25 mm with a shielding substance content of 15-60% (by weight) for geopolymer paint is up to 8.6; shielding coefficients of the electromagnetic field of microwave frequencies up to 7.9. In the presence of filler up to 60%, the reflection coefficient of the electromagnetic field of ultrahigh frequency does not exceed 0.34, while the reflection coefficient of ultramagnetic waves of ultrahigh frequency as estimated at 0.20, and the experimentally measured one is 0.22-0.23.
29
Alonso, S., A. Portela, and C. Ramis. "First considerations on the structure and development of the Iberian thermal low-pressure system." Annales Geophysicae 12, no. 5 (April 30, 1994): 457–68. http://dx.doi.org/10.1007/s00585-994-0457-x.
Full textAbstract:
Abstract. During the summer a thermal low-pressure system is locked over the Iberian Peninsula. We present a first analysis of such a system using the potential vorticity approach. Our results show that its main characteristic is the existence of a negative potential vorticity (PV) dome and a funnel-like structure for potential temperature, both located at the centre of the low. The build-up and evolution of this PV dome can be understood in terms of the dot products of the absolute vorticity and the gradient of diabetic heating vectors and the curl of the friction forces and the gradient of potential temperature vectors. The inhibition of the Algerian Mediterranean cyclogenesis during the summer seems to bear some relation to the existence of this kind of low-pressure disturbance over the Iberian Peninsula.
30
Kumar, Parichit, Saksham Malik, Ehsan Toyserkani, and Mir Behrad Khamesee. "Development of an Electromagnetic Micromanipulator Levitation System for Metal Additive Manufacturing Applications." Micromachines 13, no. 4 (April 9, 2022): 585. http://dx.doi.org/10.3390/mi13040585.
Full textAbstract:
Magnetism and magnetic levitation has found significant interest within the field of micromanipulation of objects. Additive manufacturing (AM), which is the computer-controlled process for creating 3D objects through the deposition of materials, has also been relevant within the academic environment. Despite the research conducted individually within the two fields, there has been minimal overlapping research. The non-contact nature of magnetic micromanipulator levitation systems makes it a prime candidate within AM environments. The feasibility of integrating magnetic micromanipulator levitation system, which includes two concentric coils embedded within a high permeability material and carrying currents in opposite directions, for additive manufacturing applications is presented in this article. The working principle, the optimization and relevant design decisions pertaining to the micromanipulator levitation system are discussed. The optimized dimensions of the system allow for 920 turns in the inner coil and 800 turns in the outer coil resulting in a Ninnercoil:Noutercoil ratio of 1.15. Use of principles of free levitation, which is production of levitation and restoration forces with the coils, to levitate non-magnetic conductive materials with compatibility and applications within the AM environment are discussed. The Magnetomotive Force (MMF) ratio of the coils are adjusted by incorporation of an resistor in parallel to the outer coil to facilitate sufficient levitation forces in the axial axis while producing satisfactory restoration forces in the lateral axes resulting in the levitation of an aluminum disc with a levitation height of 4.5 mm. An additional payload of up to 15.2 g (59% of mass of levitated disc) was added to a levitated aluminum disk of 26 g showing the system capability coping with payload variations, which is crucial in AM process to gradually deploy masses. The final envisioned system is expected to have positional stability within the tolerance range of a few μm. The system performance is verified through the use of simulations (ANSYS Maxwell) and experimental analyses. A novel method of using the ratio of conductivity (σ) of the material to density (ρ) of the material to determine the compatibility of the levitation ability of non-magnetic materials with magnetic levitation application is also formulated. The key advantage of this method is that it does not rely on experimental analyses to determine the levitation ability of materials.
31
Padovani, José I., Stefanie S. Jeffrey, and Roger T. Howe. "Electropermanent magnet actuation for droplet ferromicrofluidics." TECHNOLOGY 04, no. 02 (June 2016): 110–19. http://dx.doi.org/10.1142/s2339547816500023.
Full textAbstract:
Droplet actuation is an essential mechanism for droplet-based microfluidic systems. On-demand electromagnetic actuation is used in a ferrofluid-based microfluidic system for water droplet displacement. Electropermanent magnets (EPMs) are used to induce 50 mT magnetic fields in a ferrofluid filled microchannel with gradients up to 6.4 × 104 kA/m2. Short 50 µs current pulses activate the electropermanent magnets and generate negative magnetophoretic forces that range from 10 to 70 nN on 40 to 80 µm water-in-ferrofluid droplets. Maximum droplet displacement velocities of up to 300 µm/s are obtained under flow and no-flow conditions. Electropermanent magnet-activated droplet sorting under continuous flow is demonstrated using a split-junction microfluidic design.
32
Roytgarts, M., and A. Smirnov. "Turbogenerator Electromagnetic Analysis with Changing Reactive Load." Renewable Energy and Power Quality Journal 20 (September 2022): 434–37. http://dx.doi.org/10.24084/repqj20.333.
Full textAbstract:
Comparative numerical analysis of electromagnetic processes in the end zone of powerful turbogenerators has been carried out at changes in reactive load from rated duty to underexcitation, as well as performance parameters of static overload that determine the stability of synchronous operation of turbogenerators in the power system. It was demonstrated that the representation of magnetic field sources and calculation results in the form of rotating waves allows simplifying and speeding up the solution of threedimensional electromagnetic problems in the turbogenerator end zone. Using a previously developed calculation method, the electromagnetic fields and processes in over- and underexcitation modes, in particular, peculiarities of shielding in turbogenerators are studied. It was established that the added losses and electrodynamic forces in underexcitation modes acting on the outermost core packages, pressure plate, and stator shield increased by 1.5–3.0 times, resulting in accelerated aging of the turbogenerator end zone. An appropriate margin shall be provided in the cooling system and the structural design of the turbogenerator end zone. Static overload capacity in nominal conditions is determined by the ratio of maximum power to rated power. An analytical functional relationship between static overload capacity and load conditions was established. It was demonstrated that when switching to the underexcitation mode while maintaining the active load due to a decrease in the excitation current and maximum power, the static overload factor decreases to unity, that there is virtually no static stability margin of the turbogenerator in this mode. Calculations were made for turbogenerators with a capacity of 200–1111 MVA. It is recommended to limit the operation of turbogenerators in underexcitation modes and to use specialized compensators more extensively.
33
Zhang, Feilong, Lei Jiang, and Shutao Wang. "Repairable cascaded slide-lock system endows bird feathers with tear-resistance and superdurability." Proceedings of the National Academy of Sciences 115, no. 40 (September 17, 2018): 10046–51. http://dx.doi.org/10.1073/pnas.1808293115.
Full textAbstract:
Bird feathers have aroused tremendous attention for their superdurability against tears during long flights through wind and even bushes. Although feathers may inevitably be unzipped, the separated feather vanes can be repaired easily by bill stroking. However, the mechanism underlying bird feathers’ superdurability against tears remains unclear. Here, we reveal that the superdurability of bird feathers arises from their repairable cascaded slide-lock system, which is composed of hooklets, a slide rail, and spines at the end of the slide rail as terminating structures. Microscopy with a micronano manipulating system and 3D X-ray microscopy provided high-level visibility into the 3D fine structures and the entire unzipping process of feathers. The hooklets can slide along the slide rail reversibly when suffering external forces, and the sliding hooklet can be locked by the spine at the ends of barbules when larger pulling forces are applied and even slide farther away due to the unzipping of the interlocking structure with large deformation of the barbules. The elongation before separation of adjacent barbs can reach up to 270%, and the separation force can be maintained above 80% of the initial value even after 1,000 cycles of separating and repairing. These results prove that the cascaded slide-lock system ensures the superdurability of bird feathers against tears.
34
Hartansky, Rene, Martin Mierka, Vladimir Jancarik, Mikulas Bittera, Jan Halgos, Michal Dzuris, Jakub Krchnak, Jaroslav Hricko, and Robert Andok. "Towards a MEMS Force Sensor via the Electromagnetic Principle." Sensors 23, no. 3 (January 21, 2023): 1241. http://dx.doi.org/10.3390/s23031241.
Full textAbstract:
Force measurement is a science discipline that experiences significant progress with the introduction of new materials and evaluation methods. Many different sensor types, working on different principles, have been developed and reviewed and have found use in medicine as well as many other industries. New trends and demands require a size reduction and simple applicability, with the use of, for example, micro electromechanical systems (MEMS). For purposes of this study, the initial MEMS body is supplemented by its scaled version. Force measurement in this study works on the force to time-delay conversion principle. A compact compliant mechanical body (CCMB) with an embedded parallel resonant circuit (PRC) acting as a transducer realizes the conversion. Depending on the resonant frequency of the transducer (CCMB or MEMS), we have measured the applied force based on the reverse influence of the transducer on the surrounding EM field. The analysis shows that the transducer’s resonant frequency has a detectable reverse influence on the voltage-controlled oscillator (VCO) DC supply current. The force influencing the transducer is determined by the DC supply current ripple position during the VCO frequency sweep. The study presents the method proposal and mathematical analysis, as well as its function verification by simulation and prototype measurements. The proposed principle was validated on a CCMB prototype capable of measuring forces up to ∼2.5 N at a sampling frequency of ∼23 kHz, while the measured time-delay ranges from 14.5 µs to 27.4 µs.
35
Kjølhede, Klaus, and Ilmar F. Santos. "Experimental Contribution to High-Precision Characterization of Magnetic Forces in Active Magnetic Bearings." Journal of Engineering for Gas Turbines and Power 129, no. 2 (August 1, 2006): 503–10. http://dx.doi.org/10.1115/1.2434345.
Full textAbstract:
Parameter identification procedures and model validation are major steps toward intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model validation and leads to novel approaches in identifying crucial rotor parameters. This is the main focus of this paper, where an intelligent AMB is being developed with the aim of aiding the accurate identification of damping and stiffness coefficients of active lubricated journal bearings. The main contribution of the work is the characterization of magnetic forces by using two different experimental approaches. Such approaches are investigated and described in detail. A special test rig is designed where the four pole AMB is able to generate forces up to 1900N. The high-precision characterization of the magnetic forces is conducted using different experimental tests: (i) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor, (ii) by measuring the input current and bearing gap variations, monitoring the bearing input signals. Advantages and drawbacks of the different methodologies are critically discussed. The linearity ranges are experimentally determined and the characterization of magnetic forces with a high accuracy of <1% is achieved (percent error is normalized with respect to the instantaneous measured force obtained from the strain gauges signals).
36
PASHKOV, Nikolai N. "EQUATION OF MOTION MAGNETIC LEVITATION ROLLING STOCK." Transportation systems and technology 1, no. 1 (March 15, 2015): 59–69. http://dx.doi.org/10.17816/transsyst20151159-69.
Full textAbstract:
This article deals with the problem of control the trajectory of the crew magnetic levitation relative trajectory of the software regarding the track structure of the perturbation of the gravitational and magnetic fields levitation systems, lateral stabilization and traction. The crew is presented as a system of rigid bodies, whose motion is subject to gravitational and electromagnetic forces. The spatial displacement with limited powers of levitation and lateral stabilization regarding a discrete track structure are selected by drawing up the estimated equations of the dynamics of the crew as inertial coordinates of the centers of mass of solids. The coordinates of any point on the carriage in a local coordinate system are converted in the coordinate system associated with the center of mass of the crew to bring the point of application of external force to the center of mass of the crew. A general model of the dynamics of the crew is based on the equation of Lagrange-Maxwell which binds to the active mass of the external forces of gravity that govern the electromagnetic force, the force of inertia and friction. The kinetic energy of the mechanical system is defined by the velocity projections on the axis of the fixed coordinate system as a quadratic form. The crew simulated magneto elastic coupling with the track structure changing the potential energy of magnetic levitation and lateral stabilization at the deformation of the object or the displacement and rotation of the center of mass of the crew in three-dimensional space. The inverse problem of dynamics is solved to determine the control forces for a given trajectory of the crew magnetic levitation. The equations of motion the crew on a magnetic cushion are linearized regarding increments relative coordinates of the centers of mass of the crew vector and presented in the form of equations of the phase space of states.
37
Lebedev, Sergey G. "Behavior of Cosmic Rays and Propellant-Free Microwave Thruster Can Support the Hypothesis of Crystalline Vacuum." JOURNAL OF ADVANCES IN PHYSICS 14, no. 1 (March 31, 2018): 5275–80. http://dx.doi.org/10.24297/jap.v14i1.7187.
Full textAbstract:
The paper suggests an explanation of the efficiency of the EmDrive device based on the hypothesis of a crystalline vacuum, previously successfully used to explain the cutoff of the cosmic-ray spectrum. The hypothesis of crystalline vacuum enables to transform part of momentum directly to vacuum crystalline lattice giving rise to reaction force which allow to ensure the fulfillment of the momentum conservation law during EmDrive functioning. Therefore crystalline vacuum plays the role of a supporting medium for all wave vectors of electromagnetic oscillations in a conical resonator, which causes the appearance of forces and momentums of rotation, the optimization of which can open up a tempting prospect for creating of unique aircraft.
38
Kwee, Irene, and Koen Faes. "Interfacial Morphology and Mechanical Properties of Aluminium to Copper Sheet Joints by Electromagnetic Pulse Welding." Key Engineering Materials 710 (September 2016): 109–14. http://dx.doi.org/10.4028/www.scientific.net/kem.710.109.
Full textAbstract:
This study investigated joining of Al to Cu sheets by electromagnetic pulse welding, which is a solid-state welding process that uses electromagnetic forces to join materials. The interfacial morphology and mechanical properties of the Al/Cu joints were analysed and related to the welding process parameters and weld properties. The centre section of the Al/Cu joints evolved from a non-welded to a welded zone. The welded zone started with a wavy interface, consisting of thick interfacial layers with defects and evolved to a relatively flat interface without an interfacial layer. The interfacial layer thickness is determined by both the discharge energy and the stand-off distance. A higher tensile force, up to 4.9 kN, was achieved at a higher energy and a lower stand-off distance of 2 mm. The tensile force is directly related to the weld width, since a higher tensile force is achieved for a higher weld width. In addition, the presence of interfacial layers can contribute to a small extent to a higher tensile force.
39
Roulston, Benjamin R., Paul J. Green, Rodolfo Montez, Joseph Filippazzo, Jeremy J. Drake, Silvia Toonen, Scott F. Anderson, Michael Eracleous, and Adam Frank. "New Clues to the Evolution of Dwarf Carbon Stars From Their Variability and X-Ray Emission." Astrophysical Journal 926, no. 2 (February 1, 2022): 210. http://dx.doi.org/10.3847/1538-4357/ac4706.
Full textAbstract:
Abstract As main-sequence stars with C > O, dwarf carbon (dC) stars are never born alone but inherit carbon-enriched material from a former asymptotic giant branch (AGB) companion. In contrast to M dwarfs in post-mass-transfer binaries, C2 and/or CN molecular bands allow dCs to be identified with modest-resolution optical spectroscopy, even after the AGB remnant has cooled beyond detectability. Accretion of substantial material from the AGB stars should spin up the dCs, potentially causing a rejuvenation of activity detectable in X-rays. Indeed, a few dozen dCs have recently been found to have photometric variability with periods under a day. However, most of those are likely post-common-envelope binaries, spin–orbit locked by tidal forces, rather than solely spun-up by accretion. Here, we study the X-ray properties of a sample of the five nearest-known dCs with Chandra. Two are detected in X-rays, the only two for which we also detected short-period photometric variability. We suggest that the coronal activity detected so far in dCs is attributable to rapid rotation due to tidal locking in short binary orbits after a common-envelope phase, late in the thermally pulsing (TP) phase of the former C-AGB primary (TP-AGB).
40
Teixidó, Pedro, Juan Antonio Gómez-Galán, Rafael Caballero, Francisco J. Pérez-Grau, José M. Hinojo-Montero, Fernando Muñoz-Chavero, and Juan Aponte. "Secured Perimeter with Electromagnetic Detection and Tracking with Drone Embedded and Static Cameras." Sensors 21, no. 21 (November 6, 2021): 7379. http://dx.doi.org/10.3390/s21217379.
Full textAbstract:
Perimeter detection systems detect intruders penetrating protected areas, but modern solutions require the combination of smart detectors, information networks and controlling software to reduce false alarms and extend detection range. The current solutions available to secure a perimeter (infrared and motion sensors, fiber optics, cameras, radar, among others) have several problems, such as sensitivity to weather conditions or the high failure alarm rate that forces the need for human supervision. The system exposed in this paper overcomes these problems by combining a perimeter security system based on CEMF (control of electromagnetic fields) sensing technology, a set of video cameras that remain powered off except when an event has been detected. An autonomous drone is also informed where the event has been initially detected. Then, it flies through computer vision to follow the intruder for as long as they remain within the perimeter. This paper covers a detailed view of how all three components cooperate in harmony to protect a perimeter effectively, without having to worry about false alarms, blinding due to weather conditions, clearance areas, or privacy issues. The system also provides extra information of where the intruder is or has been, at all times, no matter whether they have become mixed up with more people or not during the attack.
41
ISOZAKI, HIROSHI. "QFT FOR SCALAR PARTICLES IN EXTERNAL FIELDS ON RIEMANNIAN MANIFOLDS." Reviews in Mathematical Physics 13, no. 06 (June 2001): 767–98. http://dx.doi.org/10.1142/s0129055x01000831.
Full textAbstract:
We introduce a class of noncompact Riemannian manifolds on which we can argue quantum field theory for scalar particles in external fields. More precisely, we consider quantized linear Klein–Gordon fields subject to (non quantized) electromagnetic forces in a certain class of static space-time. This class is broad enough to include physically important examples of the Euclidean space, the hyperbolic space, and by passing to the natural Lorentzian structure, the Schwarzschild metric up to conformal equivalence. The S-matrix of the massive Klein–Gordon equation on these manifolds is unitarily implemented on the Fock space constructed via the spectrum of the Laplace–Beltrami operator with scalar curvature. We also give the same result for the massless case in the asymptotically flat and hyperbolic spaces.
42
Pakkratoke, Montree, Shinnosuke Hirata, Chisato Kanamori, and Hisayuki Aoyama. "Development of Microscopic Hardness and Stiffness Investigation System with Microrobot 2nd Report, Vision Based Precise Navigation." Journal of Robotics and Mechatronics 25, no. 1 (February 20, 2013): 97–105. http://dx.doi.org/10.20965/jrm.2013.p0097.
Full textAbstract:
A microsurface measurement system that is composed of the microrobot with the indenter and a vision based navigation system is proposed for investigating hardness and stiffness of such microparts. Here the tiny robot with the electromagnetic legs and the piezo elements incorporates with an electromagnetic driven microforce generator. This force generator can provide small forces up to 17 mN with 50 µN resolutions and push down the microindenter to the surface. The displacement of the indenter head can be also measured by the Linear Valuable Differential Transformer (LVDT) on machine. Thus, this mechanism can generate the small force and monitor the depth behaviour of the indenter during whole dwell time. Since the overall size of this mechanism is small enough to implement on the piezo-driven microrobot, the tiny robot with the microindenter is capable tomove precisely step by step with 1 µm per step so that the microindenter could be penetrated anywhere on the sample surface. With the help of an image processing technique, the vision based coordination system with the local close-up view and the overall global view has been developed to identify the locations of small robot and the indenter precisely within ±3 µm accuracy over the working range. In the experimental results, several results that the indentation load-depth characteristics of the unhealthy human tooth are measured automatically at the specified point are discussed.
43
Park, S.-H., J. Lee, J. Yoo, D. Kim, and K. Park. "Effects of design and operating parameters on the static and dynamic performance of an electromagnetic valve actuator." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 217, no. 3 (March 1, 2003): 193–201. http://dx.doi.org/10.1243/09544070360550480.
Full textAbstract:
The electromagnetic valve (EMV) actuation system is a new technology for improvement in fuel effciency and reduction in emissions in spark ignition (SI) engines. It can provide more flexibility in valve event control compared with conventional variable valve actuation devices. However, a more powerful and effcient actuator design is needed for this technology to be applied in mass production engines. This paper presents the effects of design and operating parameters on the static and dynamic performances of the actuator. Employing the finite element method (FEM), the flow pattern of the magnetic flux is analysed and the resultant magnetic forces of several cases of core and armature designs are calculated. A computer simulation model has been set up to identify the dynamic behaviour of the EMV system. The effects of external disturbances such as cylinder pressure, armature neutral position and current supply time are also analysed. To verify the accuracy of the simulation model, an experimental study is also carried out on a prototype actuator. It is found that there is relatively good agreement between the experimental data and the results from the simulation model. The newly designed actuator is successfully operated on the test bench up to about 6000 r/min, which is the range of rated speed of most production SI engines. Through the whole speed range, the actuator maintains good performance in valve timing and event control.
44
Karg, Thomas M., Baptiste Gouraud, Chun Tat Ngai, Gian-Luca Schmid, Klemens Hammerer, and Philipp Treutlein. "Light-mediated strong coupling between a mechanical oscillator and atomic spins 1 meter apart." Science 369, no. 6500 (May 7, 2020): 174–79. http://dx.doi.org/10.1126/science.abb0328.
Full textAbstract:
Engineering strong interactions between quantum systems is essential for many phenomena of quantum physics and technology. Typically, strong coupling relies on short-range forces or on placing the systems in high-quality electromagnetic resonators, which restricts the range of the coupling to small distances. We used a free-space laser beam to strongly couple a collective atomic spin and a micromechanical membrane over a distance of 1 meter in a room-temperature environment. The coupling is highly tunable and allows the observation of normal-mode splitting, coherent energy exchange oscillations, two-mode thermal noise squeezing, and dissipative coupling. Our approach to engineering coherent long-distance interactions with light makes it possible to couple very different systems in a modular way, opening up a range of opportunities for quantum control and coherent feedback networks.
45
Sheu, Bor-Horng, Chih-Cheng Chiu, Wei-Ting Lu, Chu-I. Huang, and Wen-Ping Chen. "Development of UAV Tracing and Coordinate Detection Method Using a Dual-Axis Rotary Platform for an Anti-UAV System." Applied Sciences 9, no. 13 (June 26, 2019): 2583. http://dx.doi.org/10.3390/app9132583.
Full textAbstract:
The rapid development of unmanned aerial vehicles (UAVs) has led to many security problems. In order to prevent UAVs from invading restricted areas or famous buildings, an anti-UAV defense system (AUDS) has been developed and become a research topic of interest. Topics under research in relation to this include electromagnetic interference guns for UAVs, high-energy laser guns, US military net warheads, and AUDSs with net guns. However, these AUDSs use either manual aiming or expensive radar to trace drones. This research proposes a dual-axis mechanism with UAVs automatic tracing. The tracing platform uses visual image processing technology to trace and lock the dynamic displacement of a drone. When a target UAV is locked, the system uses a nine-axis attitude meter and laser rangers to measure its flight altitude and calculates its longitude and latitude coordinates through sphere coordinates to provide drone monitoring for further defense or attack missions. Tracing tests of UAV flights in the air were carried out using a DJI MAVIC UAV at a height of 30 m to 100 m. It was set up for drone image capture and visual identification for tracing under various weather conditions by a thermal imaging camera and a full-color camera, respectively. When there was no cloud during the daytime, the images acquired by the thermal imaging camera and full-color camera provide a high-quality image identification result. However, under dark weather, black clouds will emit radiant energy and seriously affect the capture of images by a thermal imaging camera. When there is no cloud at night, the thermal imaging camera performs well in drone image capture. When the drone is traced and locked, the system can effectively obtain the flight altitude and longitude and latitude coordinate values.
46
Lorenz, M., B. Heimann, and V. Härtel. "A Novel Engine Mount with Semi-Active Dry Friction Damping." Shock and Vibration 13, no. 4-5 (2006): 559–71. http://dx.doi.org/10.1155/2006/263251.
Full textAbstract:
In this paper the authors present a semi-active engine mount with a controllable friction damper. The normal force of the friction contact is applied by an electromagnetic actuator and can be varied dynamically. The nonlinear current-force-relation of the actuator is linearized. To account for wear and assembly tolerances, an initialization method is developed, that is based on indirect measurement of the actuators inductance. The friction contact is made up of industrial friction pads and a friction rod of steel. The friction model used is suitable especially for small oscillations of the friction damper. The control policy imitates viscous damping forces that exert a minimum of harmonics. Damping is activated only when necessary. Finally the friction mount is compared to the original mount in a row of test rack experiments and also in the car.
47
Diop, Mouhamadou, Frédérick Gagnon, Li Min, and Mario Fafard. "Gas Bubbles Expansion and Physical Dependences in Aluminum Electrolysis Cell: From Micro- to Macroscales Using Lattice Boltzmann Method." ISRN Materials Science 2014 (February 23, 2014): 1–11. http://dx.doi.org/10.1155/2014/454691.
Full textAbstract:
This paper illustrates the results obtained from two-dimensional numerical simulations of multiple gas bubbles growing under buoyancy and electromagnetic forces in a quiescent incompressible fluid. A lattice Boltzmann method for two-phase immiscible fluids with large density difference is proposed. The difficulty in the treatment of large density difference is resolved by using nine-velocity particles. The method can be applied to simulate fluid with the density ratio up to 1000. To show the efficiency of the method, we apply the method to the simulation of bubbles formation, growth, coalescence, and flows. The effects of the density ratio and the initial bubbles configuration on the flow field induced by growing bubbles and on the evolution of bubbles shape during their coalescence are investigated. The interdependencies between gas bubbles and gas rate dissolved in fluid are also simulated.
48
Nielsen, William Hvidtfelt Padkær, Yeghishe Tsaturyan, Christoffer Bo Møller, Eugene S. Polzik, and Albert Schliesser. "Multimode optomechanical system in the quantum regime." Proceedings of the National Academy of Sciences 114, no. 1 (December 20, 2016): 62–66. http://dx.doi.org/10.1073/pnas.1608412114.
Full textAbstract:
We realize a simple and robust optomechanical system with a multitude of long-lived (Q > 107) mechanical modes in a phononic-bandgap shielded membrane resonator. An optical mode of a compact Fabry–Perot resonator detects these modes’ motion with a measurement rate (96 kHz) that exceeds the mechanical decoherence rates already at moderate cryogenic temperatures (10 K). Reaching this quantum regime entails, inter alia, quantum measurement backaction exceeding thermal forces and thus strong optomechanical quantum correlations. In particular, we observe ponderomotive squeezing of the output light mediated by a multitude of mechanical resonator modes, with quantum noise suppression up to −2.4 dB (−3.6 dB if corrected for detection losses) and bandwidths ≲90 kHz. The multimode nature of the membrane and Fabry–Perot resonators will allow multimode entanglement involving electromagnetic, mechanical, and spin degrees of freedom.
49
Shakhov, S. I., K. N. Vdovin, Yu M. Rogachikov, and D. S. Shakhov. "Perfection of equipment for electromagnetic stirring of liquid steel in CCM molds." Ferrous Metallurgy. Bulletin of Scientific , Technical and Economic Information 75, no. 7 (August 8, 2019): 828–33. http://dx.doi.org/10.32339/0135-5910-2019-7-828-833.
Full textAbstract:
To obtain quality continuously casted billets, electromagnetic stirring (EMS) of melt is used. Most of the industrial CCM operating in Russia are equipped by EMS systems, supplied by foreign companies. EMS stators of foreign production are manufactured as a rule in nonseparable bodies and after their failures the systems must undergo expensive repair abroad at the manufacturers. At VNIIMETMASH the EMS systems of external design were created, in which this problem was solved. The version ЭМПУ 880 (EMPU 880) is completely demountable, that provides conditions for its maintenance and repair under conditions of electric shop of a plant without attraction of expensive materials and equipment. All the materials are domestic made and available. The developed facility comprises 3-phases stator submerged into water, placed in a demountable body of a corrosionresistant steel. The airproofing the body accomplished by a heat-resistant resin. Water supply into the internal area of the body and taking it away is made by end nipples. The terminal unit is arranged in the body having removable covers to connect the power mains. The output ends of the three phases are airtight in the sealing blocks under pressure of 10–12 atm. The designed EMS facility is placed at arranged locations. The peculiarities of the EMS facility design allow to increase up to 585 mm the distance to the plain of maximum rotating forces of the meniscus in the mold. Taking into account that the total energy in the active zone flow decreased and the distance to the meniscus increases, quieter meniscus can be expected at more intensive regimes of the stirring. This circumstance allow improving considerably the quality of the continuously casted billet.
50
Ausoni, Philippe, Mohamed Farhat, Xavier Escaler, Eduard Egusquiza, and François Avellan. "Cavitation Influence on von Kármán Vortex Shedding and Induced Hydrofoil Vibrations." Journal of Fluids Engineering 129, no. 8 (March 16, 2007): 966–73. http://dx.doi.org/10.1115/1.2746907.
Full textAbstract:
The present study deals with the shedding process of the von Kármán vortices at the trailing edge of a 2D hydrofoil at high Reynolds number Reh=25×103–65×103. This research focuses mainly on the effects of cavitation and fluid-structure interaction on the mechanism of the vortex generation. The vortex shedding frequency, derived from the flow-induced vibration measurement, is found to follow the Strouhal law provided that no hydrofoil resonance frequencies are excited, i.e., lock-off. For such a regime, the von Kármán vortices exhibit strong spanwise 3D instabilities and the cavitation inception index is linearly dependent on the square root of the Reynolds number. In the case of resonance, the vortex shedding frequency is locked onto the hydrofoil eigenfrequency and the spatial coherence is enhanced with a quasi-2D shape. The measurements of the hydrofoil wall velocity amplitude and phase reveal the first torsion eigenmotion. In this case, the cavitation inception index is found to be significantly increased compared to lock-off conditions. It makes clear that the vortex roll-up is amplified by the phase locked vibrations of the trailing edge. For the cavitation inception index, a new correlation relationship that encompasses the entire range of Reynolds numbers, including both the lock-off and the lock-in cases, is proposed and validated. In contrast to the earlier models, the new correlation takes into account the trailing edge displacement velocity. In addition, it is found that the transverse velocity of the trailing edge increases the vortex strength linearly. This effect is important in the context of the fluid-structure interaction, since it implies that the velocity of the hydrofoil trailing edge increases the fluctuating forces on the body. It is also demonstrated that cavitation developing in the vortex street cannot be considered as a passive agent for the turbulent wake flow. In fact, for fully developed cavitation, the vortex shedding frequency increases up to 15%, which is accompanied by the increase of the vortex advection velocity and reduction of the streamwise vortex spacing. In addition, a significant increase of the vortex-induced vibration level is found at cavitation onset. These effects are addressed and thought to be a result of the increase of the vorticity by cavitation.