Nonlinear Effects of Fluctuations in a Current-Carrying Plasma

1967 ◽  
Vol 10 (4) ◽  
pp. 685 ◽  
Author(s):  
Gary A. Pearson
Keyword(s):  
2019 ◽  
Vol 29 (04) ◽  
pp. 1950046 ◽  
Author(s):  
Tiago Leite Pereira ◽  
Aline Souza de Paula ◽  
Adriano Todorovic Fabro ◽  
Marcelo Amorim Savi

Vibration-based energy harvesting is of increasing importance and there is a current challenge to improve energy harvesting capacity exploiting nonlinear and random effects. This article investigates random effects in a nonlinear energy harvesting system. The system is represented by a magnetoelastic structure with two piezoceramic layers attached to the root of a cantilever beam, obtaining a bimorph generator. The energy harvesting system is subjected to three excitation conditions: pure harmonic, pure random and a combination of harmonic and random excitations. Noise-to-Signal Ratio (NSR) is employed to quantify different combinations of the forcing terms, establishing a procedure to evaluate the system performance. This approach is based on Power Spectral Density (PSD) of input and output signals. Numerical simulations are carried out, identifying the better combinations of harmonic and random excitations for energy harvesting purposes. Discussions about the influence of the kind of response are carried out evaluating the differences between periodic and chaotic motions. Conclusions show that both random and nonlinear effects can be tuned in order to enhance energy harvesting capacity.


MRS Bulletin ◽  
1994 ◽  
Vol 19 (3) ◽  
pp. 32-38 ◽  
Author(s):  
L. Arizmendi ◽  
F. Agulló-López

Lithium niobate (LiNbO3) is a paradigmatic photorefractive (PR) material. It provided the first experimental evidence of the PR effect and still maintains a key position in the field. This position is fostered by the fact that large congruent single crystals with good optical quality are routinely grown, enabling technological applications. A remarkable example, a PR narrow-band interference filter has recently been developed and put on the market.A relevant property of LiNbO3, the high electrooptic figure of merit, n3r, assures efficient PR performance. Another unique feature is the occurrence of a bulk photovoltaic (PV) effect, i.e., the generation of a voltage (in an open circuit) or a current (in a short circuit) as a consequence of homogeneous illumination. The bulk PV effect acts, in a way, like an internal electric field, enhancing the PR effect. On the other hand, thermal fixing or stabilization of PR gratings has been successfully accomplished through an interplay between proton and electron dynamics. LiNbO3 is also the choice substrate for the commercial fabrication of waveguide devices such as modulators, wavelength filters, multiplexers, and demultiplexers. Moreover, lasing action as well as nonlinear effects have been achieved due to the marked inhibition of the PR effect caused by heavy Mg doping. This illustrates the intimate connection between PR behavior and defect structure, i.e., between optics and materials science.


2019 ◽  
Vol 67 (6) ◽  
pp. 1047-1055
Author(s):  
James Sexton ◽  
Margaret Hilton ◽  
Stephanie Benson ◽  
Adam Rosen

A current trend emphasizes simplified models of traits and personality functioning that would reduce individuals to as few as five potential traits and one dimension of personality functioning. However, the evidence behind those models is based on linear methods of analysis that authors from Cattell to Kernberg (2016) believe do not capture the potential moderating interaction effects of personality. Using models of traits and functioning from the DSM-5, this study demonstrates not only that traits and functioning interact, but that they do so in a rich and meaningful way that points up the dangers of collapsing these concepts. Without taking the interaction into account, satisfaction in romantic or work relationships often could not be predicted or understood. If we cannot predict satisfaction in these relationships with precision, honest confusion arises over how to guide others toward these goals. Low Detachment depends on high levels of Self-Definition, just as low Antagonism relies on high levels of Empathy to be successful. Most interestingly, negative traits and low functioning can actually lead to individual satisfaction, suggesting not only that interaction is key but that nonlinear effects may also be present.


Author(s):  
R.A. Ploc

The optic axis of an electron microscope objective lens is usually assumed to be straight and co-linear with the mechanical center. No reason exists to assume such perfection and, indeed, simple reasoning suggests that it is a complicated curve. A current centered objective lens with a non-linear optic axis when used in conjunction with other lenses, leads to serious image errors if the nature of the specimen is such as to produce intense inelastic scattering.


Author(s):  
L. E. Murr ◽  
G. Wong

Palladium single-crystal films have been prepared by Matthews in ultra-high vacuum by evaporation onto (001) NaCl substrates cleaved in-situ, and maintained at ∼ 350° C. Murr has also produced large-grained and single-crystal Pd films by high-rate evaporation onto (001) NaCl air-cleaved substrates at 350°C. In the present work, very large (∼ 3cm2), continuous single-crystal films of Pd have been prepared by flash evaporation onto air-cleaved (001) NaCl substrates at temperatures at or below 250°C. Evaporation rates estimated to be ≧ 2000 Å/sec, were obtained by effectively short-circuiting 1 mil tungsten evaporation boats in a self-regulating system which maintained an optimum load current of approximately 90 amperes; corresponding to a current density through the boat of ∼ 4 × 104 amperes/cm2.


Author(s):  
Takao Suzuki ◽  
Hossein Nuri

For future high density magneto-optical recording materials, a Bi-substituted garnet film ((BiDy)3(FeGa)5O12) is an attractive candidate since it has strong magneto-optic effect at short wavelengths less than 600 nm. The signal in read back performance at 500 nm using a garnet film can be an order of magnitude higher than a current rare earth-transition metal amorphous film. However, the granularity and surface roughness of such crystalline garnet films are the key to control for minimizing media noise.We have demonstrated a new technique to fabricate a garnet film which has much smaller grain size and smoother surfaces than those annealed in a conventional oven. This method employs a high ramp-up rate annealing (Γ = 50 ~ 100 C/s) in nitrogen atmosphere. Fig.1 shows a typical microstruture of a Bi-susbtituted garnet film deposited by r.f. sputtering and then subsequently crystallized by a rapid thermal annealing technique at Γ = 50 C/s at 650 °C for 2 min. The structure is a single phase of garnet, and a grain size is about 300A.


Author(s):  
I-Fei Tsu ◽  
D.L. Kaiser ◽  
S.E. Babcock

A current theme in the study of the critical current density behavior of YBa2Cu3O7-δ (YBCO) grain boundaries is that their electromagnetic properties are heterogeneous on various length scales ranging from 10s of microns to ˜ 1 Å. Recently, combined electromagnetic and TEM studies on four flux-grown bicrystals have demonstrated a direct correlation between the length scale of the boundaries’ saw-tooth facet configurations and the apparent length scale of the electrical heterogeneity. In that work, enhanced critical current densities are observed at applied fields where the facet period is commensurate with the spacing of the Abrikosov flux vortices which must be pinned if higher critical current density values are recorded. To understand the microstructural origin of the flux pinning, the grain boundary topography and grain boundary dislocation (GBD) network structure of [001] tilt YBCO bicrystals were studied by TEM and HRTEM.


Author(s):  
A. Yamanaka ◽  
H. Ohse ◽  
K. Yagi

Recently current effects on clean and metal adsorbate surfaces have attracted much attention not only because of interesting phenomena but also because of practically importance in treatingclean and metal adsorbate surfaces [1-6]. In the former case, metals deposited migrate on the deposit depending on the current direction and a patch of the deposit expands on the clean surface [1]. The migration is closely related to the adsorbate structures and substrate structures including their anisotropy [2,7]. In the latter case, configurations of surface atomic steps depends on the current direction. In the case of Si(001) surface equally spaced array of monatom high steps along the [110] direction produces the 2x1 and 1x2 terraces. However, a relative terrace width of the two domain depends on the current direction; a step-up current widen terraces on which dimers are parallel to the current, while a step-down current widen the other terraces [3]. On (111) surface, a step-down current produces step bunching at temperatures between 1250-1350°C, while a step-up current produces step bunching at temperatures between 1050-1250°C [5].In the present paper, our REM observations on a current induced step bunching, started independently, are described.Our results are summarized as follows.(1) Above around 1000°C a step-up current induces step bunching. The phenomenon reverses around 1200 C; a step-down current induces step bunching. The observations agree with the previous reports [5].


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