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81.
The piezoelectric transformers reach densities of power more significant than their magnetic counterparts. However, one of the principal factors limiting the density of power is the acceptable maximum deformation by material constituting the transformer. The heating of the piezoelectric transformers is mainly of mechanical origin. This heating generates a degradation of the characteristics which in its turn generates an additional heating being able to lead to a phenomenon of thermal avalanche. In this work, two nonlinear methods [synchronized switch harvesting on inductor (SSHI) and SSHI-max] have been explored to improve the performance of the Rosen transformer basing on the tension generated by the secondary so as to increase the capacity of mechanic-electric conversion. The simulation results show that SSHI and SSHI-max techniques significantly increase the capacity of mechanic-electric conversion of inserts stuck on a vibrating structure and consequently, the power recovered in electric form. The comparative results of voltage gain, efficiency and the transmitted power of the transformer, before and after SSHI-max and SSHI control are given. These ones indicated that the two nonlinear techniques are promising as applications to improve the performances of the piezo-transformers.  相似文献   
82.
A decay spectroscopy study of the neutron-rich cobalt isotopes has been performed using fragmentation of a 86Kr36+ beam and the new LISE2000 spectrometer at GANIL. For 71Co and 73Co, the -delayed radiation has been observed for the first time, and the half-lives were found to be 79(5) ms and 41(4) ms, respectively. Features of the decay are discussed qualitatively in terms of nuclear models.  相似文献   
83.
In this article we investigate the complex 1D mesoscopic model of adatom diffusion and the evolution of an ordered phase on the substrate surface. The analysis of the theoretical model is compared with the experimental results of the spreading of Au adatoms on Si(111)-(7×7) surface. The steady state solutions and their stability conditions are determined within the concept of the traveling-wave solution. It is shown that the formation of the ordered phase (5×2) and the difference in the diffusion of Au on (7×7) and on (5×2) structure results in a sharp edge of diffusion front which corresponds to the coverage of a saturated (5×2) phase. This edge moves linearly in time and α can be determined by experiment. The system of model equations enables the damped waves solution or temporary evolution of two steps.  相似文献   
84.
Coincidences between two heavy fragments have been measured from the fission of 56Ni compound nuclei formed in the 32S + 24Mg reaction at E lab( ^32S ) = 165.4 MeV. A unique experimental set-up consisting of two large-area position-sensitive (x, y) gas detector telescopes has been used allowing the complete determination of the observed fragments and their momentum vectors. In addition to binary fission events with subsequent particle evaporation, narrow out-of-plane correlations are observed for two fragments emitted in purely binary events and in events with a missing charge consisting of 2α - and 3α -particles (12C). These events are interpreted as ternary cluster decay from 56Ni nuclei at high angular momenta through hyper-deformed shapes.  相似文献   
85.
A novel apparatus for a sensitive test of the independence of the speed of optical waves from the propagation direction has been developed. It employs a monolithic ULE glass structure containing two orthogonal, crossing Fabry-Perot cavities which enable common mode rejection of certain disturbances. Highly accurate locking and cavity frequency read-out are achieved using laser frequency modulation at audio frequencies. Several systematic effects were characterized. Without rotation the root Allan variance (RAV) of the beat frequency reaches a minimum of 0.5 Hz (2 × 10−15) close to the thermal noise floor of the cavities. The performance of the apparatus under rotation is demonstrated by determining with improved accuracy one parameter of the standard model extension test theory,  = (−1.0 ± 2.3) × 10−15, under simplifying assumptions.  相似文献   
86.
We report scanning tunneling microscope measurements showing a substantial decrease of the current, almost to zero, on the Si(111)-(7x7) reconstruction in the near-to-contact region under low bias conditions. First principles simulations for the tip-sample interaction and transport calculations show that this effect is driven by the substantial local modification of the atomic and electronic structure of the surface. The chemical reactivity of the adatom dangling bond states that dominate the electronic density of states close to the Fermi level and their spatial localization result in a strong modification of the electronic current.  相似文献   
87.
We present final results on inclusive production ofK *+(890),K *+(1430) andK *?(890) in \(\bar K^ + p\) interactions at 32 GeV/c, based on a statistics of ~27 events/μb. Total cross sections,p T -andx-dependence of inclusive distributions are compared with experiments at other energies and with the Lund fragmentation model. Spin density matrix elements of theK *+(890) are also discussed. The results suggest that “recombination” of both initial state valence quarks \(\bar s\) andu of theK + intoK *+(890), responsible in the Lund model for ~45% of theK *+(890) cross section, is strongly suppressed.  相似文献   
88.
The Stark effect has been studied in the odd-parity 6snf1,3F3 Rydberg series of barium with high-resolution laser-atomic-beam spectroscopy. Scalar and tensor polarizabilities have been measured of 6snf1F3 levels with n=11–30 and of 6snf3F3 levels withn = 12 ? 40. The contributions of the adjacent even-parity Rydberg levels to these polarizabilities have been calculated as far as data are available. This results in important additional information on the only partly known 6sng1,3G4 series and confirms the perturbation of these series atn = 24 by a 5d7dJ= 4 level. A tentative three-channel quantum-defect-theory analysis of the1,3G4 series has been performed. It is shown that reported level energies of the 6snd1,3D2 series are systematically 0.14 cm?1 too high.  相似文献   
89.
The branching ratios between the radiative single and double electron transitions into the doubly ionized K-shell were measured as a function of the atomic number. The results are compared with various theoretical predictions.  相似文献   
90.
Dependent on temperature and coverage, numerous spectral density functionsW(f) of the field-emission flicker noise of potassium adsorbed on the tungsten (112) plane were determined. The analysis in terms of the Timm and van der Ziel model gives surface diffusion energies between 0.55 and 0.83 eV for (average) coverages from 0.3 to 1.0 and diffusion coefficients between 2×10–10 and 3×10–9 cm2/s at 400 K. The results are compared with those obtained previously for the tungsten (111) region. Some conclusions as to the mechanism of diffusion and the manifestation of phase transitions between commensurate and incommensurate adlayer structures are discussed.On leave from Wrocaw University  相似文献   
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