scholarly journals Метод расчета поверхностных механических напряжений в осесимметричных магнитных системах

2021 ◽  
Vol 47 (9) ◽  
pp. 41
Author(s):  
А.К. Андреев
Keyword(s):  
Energy Density ◽  
Mechanical Stresses ◽  
Cylinder Diameter ◽  
Wide Range ◽  
Demagnetizing Factor ◽  
Current Systems ◽  
Long Cylinder

A method is proposed for calculating the mechanical stresses of magnetic and current systems, calculated from the energy density of a uniformly magnetized cylinder. For the calculation, an average in volume demagnetizing factor of the cylinder is introduced, which is proportional to the ratio of the cylinder diameter to its length . It is shown that the demagnetization energy , negligible for a "long" cylinder , ( ), becomes decisive in the formation of stresses at . The radial and axial stresses are investigated in a wide range of ratios.

Dependence of Granular Matrix Demagnetizing Factor on the Matrix Relative Size

2015 ◽  
Vol 1083 ◽  
pp. 32-36 ◽  
Author(s):  
Alexander Sandulyak ◽  
Anna Sandulyak ◽  
Petr Shkatov
Keyword(s):  
Magnetic Permeability ◽  
Relative Size ◽  
Dramatic Effect ◽  
Comparative Estimate ◽  
Magnetic Filter ◽  
Wide Range ◽  
Demagnetizing Factor ◽  
The Matrix ◽  
Granular Matrix ◽  
Operating Units

We note that for a wide range of porous, especially granular, ferromagnetics used as matrices of magnetic filter-separators, there is still an issue of defining their demagnetizing factor N which has a dramatic effect on the values of average magnetic permeability of these operating units of filter-separators. The work aims at filling the existent gaps in the issue, we supply N values depending on the relative size of such magnets as well as a respective generalizing phenomenological dependence which is characterized by an exponential realtion between the demagnetizing factor and relative size radical. The established relation allows obtaining real values of magnetic permeability of a short filter matrix thus providing an unbiased comparative estimate of its technological workability.

scholarly journals Large Negative Photoresistivity in Amorphous NdNiO3 Film

Coatings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1411
Author(s):  
Alexandr Stupakov ◽  
Tomas Kocourek ◽  
Natalia Nepomniashchaia ◽  
Marina Tyunina ◽  
Alexandr Dejneka
Keyword(s):  
Energy Density ◽  
Optical Absorption ◽  
Power Density ◽  
Room Temperature ◽  
Amorphous Film ◽  
Amorphous Films ◽  
Metal Insulator ◽  
Wide Range ◽  
Potential Applications

A significant decrease in resistivity by 55% under blue lighting with ~0.4 J·mm−2 energy density is demonstrated in amorphous film of metal-insulator NdNiO3 at room temperature. This large negative photoresistivity contrasts with a small positive photoresistivity of 8% in epitaxial NdNiO3 film under the same illumination conditions. The magnitude of the photoresistivity rises with the increasing power density or decreasing wavelength of light. By combining the analysis of the observed photoresistive effect with optical absorption and the resistivity of the films as a function of temperature, it is shown that photo-stimulated heating determines the photoresistivity in both types of films. Because amorphous films can be easily grown on a wide range of substrates, the demonstrated large photo(thermo)resistivity in such films is attractive for potential applications, e.g., thermal photodetectors and thermistors.

Analytical and 3D Finite Element Study of the Deflection of an Elastic Cantilever Bilayer Plate

2010 ◽  
Vol 78 (1) ◽  
Author(s):  
M. Chekchaki ◽  
V. Lazarus ◽  
J. Frelat
Keyword(s):  
Thin Films ◽  
Finite Element ◽  
Three Dimensional ◽  
Analytical Formula ◽  
Mechanical Stresses ◽  
Linear Elastic ◽  
Wide Range ◽  
Finite Element Calculations ◽  
Analytical Formulas ◽  
Three Dimensional Elasticity

The mechanical system considered is a bilayer cantilever plate. The substrate and the film are linear elastic. The film is subjected to isotropic uniform prestresses due for instance to volume variation associated with cooling, heating, or drying. This loading yields deflection of the plate. We recall Stoney’s analytical formula linking the total mechanical stresses to this deflection. We also derive a relationship between the prestresses and the deflection. We relax Stoney’s assumption of very thin films. The analytical formulas are derived by assuming that the stress and curvature states are uniform and biaxial. To quantify the validity of these assumptions, finite element calculations of the three-dimensional elasticity problem are performed for a wide range of plate geometries, Young’s and Poisson’s moduli. One purpose is to help any user of the formulas to estimate their accuracy. In particular, we show that for very thin films, both formulas written either on the total mechanical stresses or on the prestresses, are equivalent and accurate. The error associated with the misfit between our theorical study and numerical results are also presented. For thicker films, the observed deflection is satisfactorily reproduced by the expression involving the prestresses and not the total mechanical stresses.

Semantic Web Service Discovery

2011 ◽  
pp. 240-280 ◽  
Author(s):  
V. Tsetsos
Keyword(s):  
Semantic Web ◽  
Web Service ◽  
Service Discovery ◽  
Semantic Web Service ◽  
Web Service Discovery ◽  
Wide Range ◽  
Near Future ◽  
Semantic Web Service Discovery ◽  
Current Systems ◽  
Semantic Discovery

This chapter surveys existing approaches to Semantic Web service discovery. Such semantic discovery will probably substitute existing keyword-based solutions in the near future, in order to overcome the limitations of the latter. First, the architectural components along with potential deployment scenarios are discussed. Subsequently, a wide range of algorithms and tools that have been proposed for the realization of Semantic Web service discovery are presented. Moreover, key challenges and open issues, not addressed by current systems, are identified. The purpose of this chapter is to update the reader on the current progress in this area of the distributed systems domain and to provide the required background knowledge and stimuli for further research and experimentation in semantics-based service discovery.

Computational Study of Flow Resonances and Forces on a Cylinder Vibrating In-Line to a Steady Flow

2010 ◽  
Author(s):  
Lambros Kaiktsis ◽  
George S. Triantafyllou
Keyword(s):  
Oscillation Frequency ◽  
Computational Study ◽  
Oscillation Amplitude ◽  
Excitation Frequency ◽  
Spectral Element ◽  
Flow Dynamics ◽  
Chaotic Flow ◽  
Cylinder Diameter ◽  
Wide Range ◽  
Two Dimensional Flow

We present computational results of the flow dynamics and forces on a circular cylinder oscillating in-line with respect to a steady uniform stream. A wide range of oscillation frequencies is considered, from 0.5fs to 3fs, where fs is the natural Strouhal frequency of the Karman street. The oscillation amplitude is varied up to half the cylinder diameter. The Reynolds number value is 180, corresponding to two-dimensional flow. Simulations utilize a spectral element method. The computed flow states are characterized based on processed lift signals, and flow visualization. We find that the response of the flow is very sensitive to variations of the cylinder oscillation frequency. At low oscillation frequency, the lift signal and vortex patterns remain regular for low oscillation amplitudes, i.e. correspond to a 2S type of vortex street, and become complex at high oscillation amplitudes. Cylinder oscillation at the Strouhal frequency gives a window of chaotic flow at intermediate amplitudes, while at higher amplitudes 2S wakes are generated, with the sub-harmonic fs/2 and the higher harmonic 3fs/2 dominating the lift spectrum. Oscillation at twice the Strouhal frequency results in symmetric shedding, for oscillation amplitudes close to 30% of the cylinder diameter, and higher. Finally, at an oscillation frequency equal to three times the Strouhal frequency, the flow dynamics is very rich, characterized by “islands” of symmetric and asymmetric shedding at increasing oscillation amplitude. Chaotic flow is obtained only when the excitation frequency is equal to fs or to 3fs.

scholarly journals Nonaqueous redox-flow batteries: organic solvents, supporting electrolytes, and redox pairs

2015 ◽  
Vol 8 (12) ◽  
pp. 3515-3530 ◽  
Author(s):  
Ke Gong ◽  
Qianrong Fang ◽  
Shuang Gu ◽  
Sam Fong Yau Li ◽  
Yushan Yan
Keyword(s):  
Energy Density ◽  
Organic Solvents ◽  
Cell Voltage ◽  
High Energy ◽  
High Energy Density ◽  
Redox Flow Battery ◽  
High Cell ◽  
Redox Flow Batteries ◽  
Working Temperature ◽  
Wide Range

As members of the redox-flow battery (RFB) family, nonaqueous RFBs can offer a wide range of working temperature, high cell voltage, and potentially high energy density.

Analysis of the swimming of long and narrow animals

1952 ◽  
Vol 214 (1117) ◽  
pp. 158-183 ◽  
Keyword(s):  
Reynolds Number ◽  
Wave Length ◽  
Constant Speed ◽  
Forward Speed ◽  
Constant Amplitude ◽  
Flexible Cylinder ◽  
Cylinder Diameter ◽  
Wide Range ◽  
The Waves ◽  
Marine Worms

The swimming of long animals like snakes, eels and marine worms is idealized by considering the equilibrium of a flexible cylinder immersed in water when waves of bending of constant amplitude travel down it at constant speed. The force of each element of the cylinder is assumed to be the same as that which would act on a corresponding element of a long straight cylinder moving at the same speed and inclination to the direction of motion. Relevant aerodynamic data for smooth cylinders are first generalized to make them applicable over a wide range of speed and cylinder diameter. The formulae so obtained are applied to the idealized animal and a connexion established between B / λ , V / U and R 1 . Here B and λ are the amplitude and wave-length, V the velocity attained when the wave is propagated with velocity U , R 1 is the Reynolds number Udρ / μ , where d is the diameter of the cylinder, ρ and μ are the density and viscosity of water. The results of calculation are compared with James Gray’s photographs of a swimming snake and a leech. The amplitude of the waves which produce the greatest forward speed for a given output of energy is calculated and found, in the case of the snake, to be very close to that revealed by photographs. Similar calculations using force formulae applicable to rough cylinders yield results which differ from those for smooth ones in that when the roughness is sufficiently great and has a certain directional character propulsion can be achieved by a wave of bending which is propagated forward instead of backward. Gray’s photographs of a marine worm show that this remarkable method of propulsion does in fact occur in the animal world.

REITERATED HOMOGENIZATION OF INTEGRAL FUNCTIONALS

2000 ◽  
Vol 10 (01) ◽  
pp. 47-71 ◽  
Author(s):  
ANDREA BRAIDES ◽  
DAG LUKKASSEN
Keyword(s):  
Energy Density ◽  
Quadratic Form ◽  
Phase Structure ◽  
Effective Properties ◽  
Effective Property ◽  
Integral Functionals ◽  
Effective Energy ◽  
Two Phase ◽  
Wide Range ◽  
Reiterated Homogenization

We consider the homogenization of sequences of integral functionals defined on media with several length-scales. Our general results connected to the corresponding homogenized functional are used to analyze new types of structures and to illustrate the wide range of effective properties achievable through reiteration. In particular, we consider a two-phase structure which is optimal when the integrand is a quadratic form and point out examples where the macroscopic behavior of this structure underlines an effective energy density which is lower than that of the best possible multirank laminate. We also present some results connected to a reiterated structure where the effective property is extremely sensitive of the growth of the integrand.

scholarly journals Generation and transportation of high-intensity pulsed ion beam at varying background pressures

2017 ◽  
Vol 35 (4) ◽  
pp. 587-596 ◽  
Author(s):  
X.P. Zhu ◽  
L. Ding ◽  
Q. Zhang ◽  
Yu. Isakova ◽  
Y. Bondarenko ◽  
...  
Keyword(s):  
Energy Density ◽  
High Intensity ◽  
Focal Point ◽  
Ion Beam ◽  
Industrial Applications ◽  
Ion Source ◽  
Beam Deflection ◽  
Appreciable Change ◽  
Energy Density Distribution ◽  
Wide Range

AbstractHigh-intensity pulsed ion beam (HIPIB) technology is developed as an advanced manufacturing method for components with improved wear, corrosion and/or fatigue performance, etc. Robust HIPIB equipment with stable repetitive operation, long-lifetime, and easy maintenance are desired for industrial applications, on which stability of ion beam parameters is critical to achieve consistent result of reproducibility. Here, magnetically insulated ion diodes (MIDs) as ion source with durable graphite anode are investigated in a simple self-magnetic field configuration under repetitive operation. Influence of background pressure on ion beam generation and transportation is emphasized since ion beam sources were intrinsically a vacuum-based system. Comparative experiments were conducted on two types of HIPIB equipment, that is, TEMP-6 and TEMP-4M, differing in vacuum packages where turbo-molecular pump or oil diffusion pump was used. Both the HIPIB equipments are operated on a bipolar pulse mode, that is, a first negative pulse of 150–200 kV with pulse duration 450–500 ns to generate anode plasma on explosive electron emission, and a second positive pulse of 200–250 kV with 120 ns to accelerate the ions. Ion beam energy density up to 8 J/cm2 is achievable using MIDs of geometrical focusing configuration, and the total energy, energy density distribution along cross-section, deflection and divergence, and charge neutralization of the ion beams are assessed under background pressures in a wide range of two orders of magnitude, that is, 1–100 mPa. No appreciable change in the parameters is observed up to 50 mPa, and merely a slight increase in the beam deflection from about ±3 mm to about ±4 mm at the focal point over 50 mPa. The stability of ion beam at the varied pressure is mainly facilitated by the higher pressure up to several Pa in anode–cathode gap during plasma generation and good neutralizing effect for ion beam transportation.

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