scholarly journals Efficiency estimation for permanent magnets of synchronous wind generators

2014 ◽  
Vol 51 (1) ◽  
pp. 21-31 ◽  
Author(s):  
A. Serebryakov ◽  
N. Levin ◽  
A. Sokolov ◽  
E. Kamolins
Keyword(s):  
Magnetic Field ◽  
Permanent Magnets ◽  
Direct Action ◽  
High Energy ◽  
Electrical Machine ◽  
Maintenance Costs ◽  
Wind Generators ◽  
Efficiency Estimation ◽  
Indirect Action ◽  
Proper Orientation

Abstract Application of wind generators opens wide possibilities for raising the efficiency of low- and medium-power wind generators (WGs). The mass of generators in the proposed version is smaller, their reliability higher, while maintenance costs are lower. At the same time, the use of high-energy permanent magnets in generators of enhanced power comes up against some obstacles, which can be overcome through proper orientation of magnetization at creation of a magnetic field in the airgap of electrical machine. In this regard, it might be preferable to use magnets with indirect action on the airgap instead of those with direct action. A convincing example of the former variant is a generator with tangentially oriented magnetization of permanent magnets. In the work, an attempt is done to prove the advantages of such installation in modern low- and medium-power WGs

Magnetorheological dampers with various designs of hybrid magnetic circuits

2012 ◽  
Vol 23 (9) ◽  
pp. 979-987 ◽  
Author(s):  
Holger Böse ◽  
Johannes Ehrlich
Keyword(s):  
Magnetic Field ◽  
Permanent Magnets ◽  
Magnetic Circuit ◽  
High Energy ◽  
Magnetorheological Dampers ◽  
Magnetic Field Generation ◽  
Magnetic Circuits ◽  
Hard Magnet ◽  
Large Effort ◽  
The Magnetic Field

Novel concepts for the magnetic circuit in magnetorheological dampers have been proven. In contrast to the established magnetic circuits where the magnetic field for the control of the magnetorheological fluid is generated by the coil of an electromagnet, hybrid magnetic circuits consisting of at least one permanent or hard magnet and an electromagnet are used in the new approaches. Three different technical configurations are distinguished: (1) The electromagnet is combined with two permanent magnets, whose magnetization cannot be modified even by strong magnetic fields of the electromagnet. The main advantage is the improved fail-safe behavior of the damper in case of a power failure. (2) The electromagnet is combined with a hard magnet, whose magnetization can be modified by the electromagnet. This configuration leads to high energy efficiency, because electric power is only required in short pulses for the switching of the hard magnet. (3) All three types of magnetic field sources, permanent, hard, and electromagnet, are combined in the magnetic circuit, which gives the highest flexibility of the magnetic field generation and the damping control at the expense of a relatively large effort. Demonstrators for magnetorheological dampers with all three magnetic circuits were constructed and their performances were tested. The results of the investigations are described in this paper.

scholarly journals Efficient Toughening of Short-Fiber Composites Using Weak Magnetic Fields

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2415
Author(s):  
Omri Goldberg ◽  
Israel Greenfeld ◽  
Hanoch Daniel Wagner
Keyword(s):  
Magnetic Field ◽  
Fracture Toughness ◽  
Magnetic Fields ◽  
Permanent Magnets ◽  
Glass Fibers ◽  
High Energy ◽  
Short Fiber ◽  
Local Concentration ◽  
Weak Magnetic Fields ◽  
Energy Dissipated

Short fibers may serve as toughening agents of composite materials because of the high energy dissipated during fracture, associated with numerous fiber pullouts. An ongoing challenge is to improve their toughness even further, by directing and concentrating fibers near highly stressed structural regions. Weak magnetic fields are utilized to increase the fracture toughness of an epoxy matrix reinforced by short magnetized glass fibers by directing and concentrating fibers near highly stressed structural regions. The orientation and local concentration of the fibers are controlled by the vector components of the magnetic field, and by the gradient in field intensity, respectively. Optimized fracture toughness was achieved by using two pairs of permanent magnets, combining enhanced concentration of fibers in the crack-tip vicinity with alignment of the fibers along the load direction. This optimized value was well above the reference fracture-toughness measured for composites with the same filler content in the absence of a magnetic field, as well as above the value achieved by exploiting unidirectional alignment, without fiber translation, using a solenoid. The method suggested in this study—localized reinforcement using magnetic translation of fillers through the formation of magnetic gradients—enables efficient and controllable improvement in the composite’s overall resistance to fracture, without the involvement of additional phases or material.

Novel Adaptive Damping Systems Based on Magnetorheological Fluids

2012 ◽  
Vol 77 ◽  
pp. 86-95
Author(s):  
Holger Böse ◽  
Johannes Ehrlich
Keyword(s):  
Magnetic Field ◽  
Permanent Magnets ◽  
High Energy ◽  
Continuous Control ◽  
Magnetorheological Dampers ◽  
Short Pulses ◽  
Magnetic Circuits ◽  
Hard Magnet ◽  
Fail Safe ◽  
Damping Systems

Adaptive damping systems based on magnetorheological (MR) fluids allow the continuous control of vibration damping forces depending on the current conditions. In magnetorheological dampers known so far, the magnetic field for the control of the MR fluid is generated by the coil of an electromagnet. Two novel concepts for the magnetic circuit in magnetorheological dampers have been proven where hybrid magnetic circuits consisting of at least one permanent or hard magnet and an electromagnet are used. In the first concept, the electromagnet is combined with two permanent magnets, whose magnetization cannot be modified even by strong magnetic fields of the electromagnet. The main advantage of this configuration is the improved fail-safe behaviour of the damper in case of a power failure. In the second approach, the electromagnet is combined with a hard magnet, whose magnetization can be modified by the electromagnet. This configuration leads to high energy efficiency, because electric power is only required in short pulses for the switching of the hard magnet. Magnetic circuits with the combination of different magnetic field sources were designed supported by simulations of the magnetic flux distribution. Demonstration models for magnetorheological dampers with the distinguished magnetic circuits were constructed and their performances were tested. The results of the investigations are described in this contribution.

Patent Conflicts

2017 ◽  
Author(s):  
Tejas N. Narechania
Keyword(s):  
Regulatory Authority ◽  
Direct Action ◽  
Patent Policy ◽  
Context Sensitive ◽  
Court Of Appeals ◽  
Relative Preference ◽  
The Supreme Court ◽  
Federal Circuit ◽  
Indirect Action ◽  
Striking Effect

Patent policy is typically thought to be the product of the Patent and Trademark Office, the Court of Appeals for the Federal Circuit, and, in some instances, the Supreme Court. This simple topography, however, understates the extent to which outsiders can shape the patent regime. Indeed, a variety of administrative actors influence patent policy through the exercise of their regulatory authority and administrative power. This Article offers a novel description of the ways in which nonpatent agencies intervene into patent policy. In particular, it examines agency responses to conflicts between patent and other regulatory aims, uncovering a relative preference for complacency (“inaction”) and resort to outside help (“indirect action”) over regulation (“direct action”). This dynamic has the striking effect of shifting authority from nonpatent agencies to patent policymakers, thereby supplanting some regulatory designs with the patent regime’s more general incentives. This Article thus offers agencies new options for facing patent conflict, including an oft-overlooked theory of regulatory authority for patent-related regulation. Such intervention and regulation by nonpatent agencies can give rise to a more efficient and context-sensitive regime that is better aligned with other regulatory goals.

scholarly journals Design of a New 1D Halbach Magnet Array with Good Sinusoidal Magnetic Field by Analyzing the Curved Surface

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2522
Author(s):  
Guangdou Liu ◽  
Shiqin Hou ◽  
Xingping Xu ◽  
Wensheng Xiao
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Permanent Magnet ◽  
Flux Density ◽  
Permanent Magnets ◽  
Air Gap ◽  
Curved Surface ◽  
Magnetic Flux Density ◽  
Sinusoidal Magnetic Field ◽  
The Magnetic Field

In the linear and planar motors, the 1D Halbach magnet array is extensively used. The sinusoidal property of the magnetic field deteriorates by analyzing the magnetic field at a small air gap. Therefore, a new 1D Halbach magnet array is proposed, in which the permanent magnet with a curved surface is applied. Based on the superposition of principle and Fourier series, the magnetic flux density distribution is derived. The optimized curved surface is obtained and fitted by a polynomial. The sinusoidal magnetic field is verified by comparing it with the magnetic flux density of the finite element model. Through the analysis of different dimensions of the permanent magnet array, the optimization result has good applicability. The force ripple can be significantly reduced by the new magnet array. The effect on the mass and air gap is investigated compared with a conventional magnet array with rectangular permanent magnets. In conclusion, the new magnet array design has the scalability to be extended to various sizes of motor and is especially suitable for small air gap applications.

scholarly journals Scaling parameter of the lethal effect of mammalian cells based on radiation-induced OH radicals: effectiveness of direct action in radiation therapy

2020 ◽  
Vol 62 (1) ◽  
pp. 86-93
Author(s):  
Tamon Kusumoto ◽  
Ryo Ogawara ◽  
Kazuyo Igawa ◽  
Kentaro Baba ◽  
Teruaki Konishi ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Direct Action ◽  
Absorbed Dose ◽  
Vertical Axis ◽  
Lethal Effect ◽  
Cell Killing ◽  
Oh Radicals ◽  
Survival Curves ◽  
Biological Effectiveness ◽  
Indirect Action

ABSTRACT We have been studying the effectiveness of direct action, which induces clustered DNA damage leading to cell killing, relative to indirect action. Here a new criterion Direct Ation-Based Biological Effectiveness (DABBLE) is proposed to understand the contribution of direct action for cell killing induced by C ions. DABBLE is defined as the ratio of direct action to indirect action. To derive this ratio, we describe survival curves of mammalian cells as a function of the number of OH radicals produced 1 ps and 100 ns after irradiation, instead of the absorbed dose. By comparing values on the vertical axis of the survival curves at a certain number of OH radicals produced, we successfully discriminate the contribution of direct action induced by C ions from that of indirect action. DABBLE increases monotonically with increasing linear energy transfer (LET) up to 140 keV/μm and then drops, when the survival curves are described by the number of OH radicals 1 ps after irradiation. The trend of DABBLE is in agreement with that of relative biological effectiveness (RBE) of indirect action. In comparison, the value of DABBLE increases monotonically with LET, when the survival curves are described by the number of OH radicals 100 ns after irradiation. This finding implies that the effectiveness of C ion therapy for cancer depends on the contribution of direct action and we can follow the contribution of direct action over time in the chemical phase.

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