Search results for " loss"
showing 10 items of 1342 documents
Discrete spectral incoherent solitons in nonlinear media with noninstantaneous response
2011
International audience; We show theoretically that nonlinear optical media characterized by a finite response time may support the existence of discrete spectral incoherent solitons. The structure of the soliton consists of three incoherent spectral bands that propagate in frequency space toward the low-frequency components in a discrete fashion and with a constant velocity. Discrete spectral incoherent solitons do not exhibit a confinement in the space-time domain, but exclusively in the frequency domain. The kinetic theory describes in detail all the essential properties of discrete spectral incoherent solitons: A quantitative agreement has been obtained between simulations of the kinetic…
Formation of dislocations and hardening of LiF under high-dose irradiation with 5–21 MeV 12C ions
2017
R. Zabels, I. Manika, J. Maniks, and R.Grants acknowledge the national project IMIS2, and A. Dauletbekova, M. Baizhumanov, and M. Zdorovets the Ministry of Education and Science of the Republic of Kazakhstan for the financial support.
New fine structures resolved at the ELNES Ti-L2,3 edge spectra of anatase and rutile: comparison between experiment and calculation.
2010
Abstract Anatase and rutile Ti- L 2,3 edge spectra were measured in electron energy loss spectroscopy (EELS) using a transmission electron microscope (TEM) coupled to a CEOS Cs-probe corrector, an omega-type monochromator and an in-column omega-type energy filter fully corrected for 2nd order aberrations. Thanks to the high energy resolution, high electron probe current and high stability achieved under this instrumental configuration, new fine structures, never reported before, were resolved at the L 3 band of both rutile and anatase. The data suggest that new peaks also exist in the L 2 e g band. The experimental spectra are compared with multichannel multiple scattering (MMS) calculation…
Structural characterization of TiO2/TiN O (δ-doping) heterostructures on (1 1 0)TiO2 substrates
2003
Abstract TiO2/TiNxOy δ-doping structures were grown on the top of (1 1 0)TiO2 rutile substrates by low pressure metal-organic vapor phase epitaxy (LP-MOVPE) technique at 750 °C. The samples were analyzed by high resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy (EELS) and X-ray diffraction techniques (rocking curves and φ-scans). The presence of satellites in the (1 1 0)TiO2 rocking curve revealed the epitaxial growth of 10 period δ-doping structures. The thickness of the TiO2 layers, 84 nm, was deduced from the satellites period. HRTEM observations showed around 1.5 nm thick δ-doping layers, where the presence of nitrogen was detected by EELS. The analy…
Improve the dielectric properties of PrSrNi0.8Mn0.2O4 compounds by longer mechanical milling
2018
Abstract Structural and dielectric properties of PrSrNi 0.8 Mn 0.2 O 4 ceramics elaborated by a rapid method combining mechanical milling and heat treatment were studied for the first time. The raw materials are milled at different times ( t mil = 0, 5, 10, 20 and 30 h) and annealed at 1300 °C for 8 h to produce a revealed PrSrNi 0.8 Mn 0.2 O 4 single phase, exhibiting tetragonal structure with space group I 4/ mmm . This result was confirmed by using the TEM/ED pattern for sample milled at 30 h using the [001] orientation. The corresponding lattice images show a well-ordered compound, indicating the absence of stacking faults and the growth of the crystallites. Giant dielectric response …
Enhancement of the dielectric response through Al-substitution in La1.6Sr0.4NiO4 nickelates
2016
The structures and dielectric properties of La1.6Sr0.4Ni1−xAlxO4 (x = 0, 0.2 and 0.4) ceramics elaborated using the Pechini method were studied for the first time. The same unique tetragonal phase was found in all compounds. The lattice parameters were found using Rietveld refinement. The surface morphology characterization and elemental analysis of these samples were respectively carried out using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). A giant dielectric response was observed in these ceramics, and one dielectric relaxation was found. The substitution of nickel with aluminum results in a colossal dielectric constant value (>106). The dielectric l…
Microwave properties and structure of La–Ti–Si–B–O glass-ceramics for applications in GHz electronics
2017
Abstract A dielectric bulk glass-ceramic of the La 2 O 3 –TiO 2 –SiO 2 –B 2 O 3 system is developed which is able to fulfill the requirements for dielectric loading-based mobile communication technologies. It is shown that the given dielectric requirements can be fulfilled by glass-ceramic materials without being dependent on ceramic processing techniques. The material exhibited permittivity values of 20 ɛ r Qf τ f τ f material with a Qf value of 9500 GHz and ɛ r = 21.4 could be achieved at a ceramming temperature T cer = 870 °C. The material is aimed to provide an alternative to existing, commercially used sintered ceramic materials. Further focus is laid on the investigation of the dom…
Domain Walls Motions in Barium Titanate Ceramics
1996
The shear modulus and mechanical loss at low frequencies (0.01, 0.3, 1 Hz) are measured by an inverted pendulum for BaTiO 3 ceramic with large grain sizes. The permittivity and dielectric losses are also investigated for the same material at higher frequencies between 1 and 100 kHz as function of temperature. Those results show several relaxation peaks in the ferroelectric phases. The activation energy of each peak is obtained to be 0.29, 0.45, 0.68, 0.92 eV. The influences of strain amplitude and thermal treatments are studied specially for the mechanical relaxation peak located in the tetragonal phase. All the relaxation peaks could be associated to the interaction of oxygen vacancies in …
Enhanced loss model algorithm for interior permanent magnet synchronous machines
2017
This paper presents an experimental study on the impact of the parameter variations over the performances of a LMA (Loss Model Algorithm) designed for an IPMSM (Interior Permanent Magnet Synchronous Machine). In a previous work, the characterization was carried out by assessing, for several working conditions, the motor parameters that influence the motor efficiency. The proposed enhanced loss model algorithm is implemented in a rapid prototyping system and its performances, in term of efficiency, are compared with other control systems, obtaining promising results.
Geographic and temporal variations in turbulent heat loss from lakes : A global analysis across 45 lakes
2018
Heat fluxes at the lake surface play an integral part in determining the energy budget and thermal structure in lakes, including regulating how lakes respond to climate change. We explore patterns in turbulent heat fluxes, which vary across temporal and spatial scales, using in situ high-frequency monitoring data from 45 glob- ally distributed lakes. Our analysis demonstrates that some of the lakes studied follow a marked seasonal cycle in their turbulent surface fluxes and that turbulent heat loss is highest in larger lakes and those situated at low latitude. The Bowen ratio, which is the ratio of mean sensible to mean latent heat fluxes, is smaller at low lati- tudes and, in turn, the rel…