scholarly journals Measurements of elastic properties of langatate at liquid helium temperatures for design of ultra low loss mechanical systems

2014 ◽  
Vol 104 (26) ◽  
pp. 261904 ◽  
Author(s):  
Maxim Goryachev ◽  
Philippe Abbé ◽  
Bernard Dulmet ◽  
Roger Bourquin ◽  
Serge Galliou
Keyword(s):  
Liquid Helium ◽  
Elastic Properties ◽  
Mechanical Systems ◽  
Low Loss

A New Device for the Solution of Transient-Vibration Problems by the Method of Electrical-Mechanical Analogy

1945 ◽  
Vol 12 (3) ◽  
pp. A135-A141
Author(s):  
H. E. Criner ◽  
G. D. McCann ◽  
C. E. Warren
Keyword(s):  
Mechanical Systems ◽  
Low Loss ◽  
Transient Vibration ◽  
Electrical Circuits ◽  
New Device ◽  
Mechanical Analogy ◽  
Vibration Problems ◽  
Short Circuits ◽  
Transient Voltages ◽  
Force Displacement

Abstract This paper describes a new device, the mechanical-transients analyzer, for solving transient-vibration problems by the principle of electrical-mechanical analogy. Analogous electrical circuits are used to represent a mechanical system. For these, special low-loss electrical elements have been developed so that low-loss mechanical systems can be studied. The transient excitation functions, such as force, displacement, or velocity, are applied to the equivalent mechanical circuit as transient voltages or currents by means of special electrical circuits developed for the purpose. The various electrical-mechanical analogies that can be used for problems of this type are discussed, and it is shown that the principal factor determining the choice of analogy is the mechanical variable that it is desired to record. The use of the device is illustrated for several types of problems, including the ridability of vehicles, and the shaft torques developed in turbogenerators by electrical short-circuits. Many other problems involving transients in mechanical systems can be solved with this method.

FORCED TORSIONAL VIBRATIONS IN THE PRESENCE OF RESISTANCE FORCES

2015 ◽  
Vol 8 (1) ◽  
pp. 9-11
Author(s):  
Беляев ◽  
Aleksandr Belyaev ◽  
Тришина ◽  
Tatyana Trishina
Keyword(s):  
Differential Equations ◽  
Mechanical System ◽  
Elastic Properties ◽  
Mechanical Systems ◽  
Torsional Vibrations ◽  
Rational Selection ◽  
Torsional Oscillations ◽  
Properties Of Materials ◽  
Resistance Forces ◽  
Selection Of

The work proposed differential equations describing the torsional oscillations of one- and two-mass mechanical systems taking into account the dissipative losses of various kinds and nature. The dependences for determining the equivalent rigidity of the elastic ties. Using the results of these studies can be realized rational selection of inertial and elastic properties of materials and components damper mechanical system

RF-MEMS Components for Wireless Transceivers

2012 ◽  
pp. 156-188
Author(s):  
Masoud Baghelani ◽  
Habib Badri Ghavifekr ◽  
Afshin Ebrahimi
Keyword(s):  
Rf Mems ◽  
Mechanical Systems ◽  
Low Power Consumption ◽  
Cmos Process ◽  
Low Loss ◽  
Wireless Transceivers ◽  
Micro Electro Mechanical Systems ◽  
Rf Transceivers ◽  
Power Handling ◽  
On Chip

The application of Micro-Electro-Mechanical-Systems (MEMS) in the fields of radio frequency and microwave is offensively spreading. Nowadays a large amount of scientists and research centers worldwide are involved with development, design, and fabrication of MEMS components for RF applications. RF-MEMS show numerous capabilities for improving the performance of RF transceivers. Their excellent features such as extremely low power consumption, low loss, simple and cheap fabrication process, the ability to work at UHF and SHF frequencies, and compatibility with standard CMOS process make them ideal devices replacing the bulky off-chip components and enhancing the performance of on-chip circuits of transceivers. Therefore they can realize the idea of a transceiver on a chip. The aim of this chapter is to provide a reader with deep information in the field of RF-MEMS, covering their current and possible applications, design, modeling, and simulation. Also their problems such as power handling, packaging, frequency extension, et cetera, are discussed. In addition, this chapter will introduce case studies in RF-MEMS area for researchers.

scholarly journals Engineering Properties of Superconducting Materials

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4652
Author(s):  
Tim Coombs
Keyword(s):  
High Temperature ◽  
Liquid Helium ◽  
High Temperature Superconductors ◽  
Engineering Properties ◽  
Fault Current ◽  
High Current ◽  
Special Issue ◽  
Low Loss ◽  
New Class ◽  
Fault Current Limiters

Taking a technology from the laboratory to industry is a long and resource-consuming process. Discovered more than a century ago, the phenomenon of superconductivity is testament to this process. Despite the promise of this technology, currently the only major use of superconductors outside the laboratory is in MRI machines. The advent of high-temperature superconductors in 1986 heralded a new dawn. Machines which do not require cooling with liquid helium are a very attractive target. A myriad range of different superconductors were rapidly discovered over the next decade. This process of discovery continues to this day with, most recently, a whole new class, the pnictides, being discovered in 2006. Many different usages have been identified, including in motors, generators, wind turbines, fault current limiters, and high-current low-loss cables. This Special Issue looks at some of the different factors which will help to realise these devices and thereby bring about a superconducting world

A Superconducting Microscope

1971 ◽  
Vol 29 ◽  
pp. 10-11 ◽  
Author(s):  
R. E. Worsham ◽  
J. E. Mann ◽  
E. G. Richardson
Keyword(s):  
Liquid Helium ◽  
Focal Length ◽  
Vacuum System ◽  
Objective Lens ◽  
Electrical Instability ◽  
Radiation Shields ◽  
And Control ◽  
Thermal Oscillations ◽  
Flux Pump

This superconducting microscope, Figure 1, was first operated in May, 1970. The column, which started life as a Siemens Elmiskop I, was modified by removing the objective and intermediate lenses, the specimen chamber, and the complete vacuum system. The large cryostat contains the objective lens and stage. They are attached to the bottom of the 7-liter helium vessel and are surrounded by two vapor-cooled radiation shields.In the initial operational period 5-mm and 2-mm focal length objective lens pole pieces were used giving magnification up to 45000X. Without a stigmator and precision ground pole pieces, a resolution of about 50-100Å was achieved. The boil-off rate of the liquid helium was reduced to 0.2-0.3ℓ/hour after elimination of thermal oscillations in the cryostat. The calculated boil-off was 0.2ℓ/hour. No effect caused by mechanical or electrical instability was found. Both 4.2°K and 1.7-1.9°K operation were routine. Flux pump excitation and control of the lens were quite smooth, simple, and, apparently highly stable. Alignment of the objective lens proved quite awkward, however, with the long-thin epoxy glass posts used for supporting the lens.

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