The dependence of the beam propagation factor (M2 parameter) with the absorbed pump power in the case of monolithic microchip laser under face-cooled configuration is extensively
studied. Our investigations show that the M2 parameter is related to the absorbed pump power through two parameters (α and β) whose values depend on the laser material properties and laser configuration. We have shown that one parameter arises due
to the oscillation of higher order modes in the microchip cavity and the other parameter accounts for the spherical aberration
associated with the thermal lens induced by the pump beam. Such dependency of M2 parameter with the absorbed pump power is experimentally verified for a face-cooled monolithic microchip laser based on Nd3+ -doped GdVO4 crystal and the values of α and β parameters were estimated from the experimentally measured data points. 相似文献
In this paper, we summarize the issues that should be considered when designing broadband quasioptical systems for submillimetre-wave radioastronomy receivers. We cover topics such as bandwidth, cross-talk, truncation, and aberrations, and we argue that it should be possible to manufacture high-efficiency systems that have several octaves of bandwidth. A key feature of the paper is that we use the language of multimode Gaussian optics throughout, and in this way, we emphasize that a receiver is a diffraction-limited imaging system rather than just a collection of components for guiding Gaussian beams. The whole discussion is conducted in terms of a particular system we are constructing for the James Clerk Maxwell Telescope in Hawaii. 相似文献
Traditional ensiling of plant material by anaerobic lactic acid fermentation was combined with enzymatic hydrolysis (ENLAC for short) with cell wall degrading enzymes (hemicellulases, cellulases, and pectinases) to increase fiber digestibility or to increase the recovery of cell content from plants. Such findings were made using 0.015% (w/w, wet basis) Phylacell® enzyme preparation by ENLAC of corn and corn-sorghum mixtures, but not of forage grasses. Addition to alfalfa of a mixture of cell wall degrading enzymes, such as NOVO Viscozyme® together with NOVO Celluclast® each at 0.2–1.0% (w/w, wet basis), resulted in more rapid ensiling and improvement of rumen digestibility of silage by 20%. After 20 d of ensiling at 25 °C when the same enzymes were added to alfalfa at the 1.0% level, protein recovery by pressing increased by 35%, β-carotene recovery by 80%, and chlorophyll/xanthophyll recovery by 30%. ENLAC with the same enzymes also increased the recovery of sclareol from muscatel sage by 400%.
The focus of this paper is the optimization of complex multi-parameter systems. We consider systems in which the objective function is not known explicitly, and can only be evaluated through computationally intensive numerical simulation or through costly physical experiments. The objective function may also contain many local extrema which may be of interest. Given objective function values at a scattered set of parameter values, we develop a response surface model that can dramatically reduce the required computation time for parameter optimization runs. The response surface model is developed using radial basis functions, producing a model whose objective function values match those of the original system at all sampled data points. Interpolation to any other point is easily accomplished and generates a model which represents the system over the entire parameter space. This paper presents the details of the use of radial basis functions to transform scattered data points, obtained from a complex continuum mechanics simulation of explosive materials, into a response surface model of a function over the given parameter space. Response surface methodology and radial basis functions are discussed in general and are applied to a global optimization problem for an explosive oil well penetrator. 相似文献
Heavy ion irradiation in the electronic stopping power region induces macroscopic dimensional change in metallic glasses and introduces magnetic anisotropy in some magnetic materials. The present work is on the irradiation study of ferromagnetic metallic glasses, where both dimensional change and modification of magnetic anisotropy are expected. Magnetic anisotropy was measured using Mössbauer spectroscopy of virgin and irradiated Fe40Ni40B20 and Fe40Ni38Mo4B18 metallic glass ribbons. 90 MeV 127I beam was used for the irradiations. Irradiation doses were 5×1013 and 7.5×1013 ions/cm2. The relative intensity ratios D23 of the second and third lines of the Mössbauer spectra were measured to determine the magnetic anisotropy. The virgin samples of both the materials display in-plane magnetic anisotropy, i.e., the spins are oriented parallel to the ribbon plane. Irradiation is found to cause reduction in magnetic anisotropy. Near-complete randomization of magnetic moments is observed at high irradiation doses. Correlation is found between the residual stresses introduced by ion irradiation and the change in magnetic anisotropy. 相似文献
Lanreotide peptide was labeled with 153Sm-H1ETA and 188Re-MAG3 in order to evaluate whether or not their conjugation to the peptide produce significant differences of the in vitro lipophilicity with respect to the 188Re-lanreotide prepared by the direct labeling method (highly lipophilic). The differences of lipophilicity between the complexes, were evaluated using a reverse phase HPLC system. The measured lipophilicity of 153Sm-H1ETA-lanreotide, 188Re-MAG3-lanreotide and 188Re-lanreotide was taken to be the capacity factor [k" = (tR-t0)/t0 where tR is the retention time and t0 is the dead time] for each of the complexes under identical chromatography conditions. Results showed that the in vitro lipophilicity decreased in the order 188Re-lanreotide (direct labeling), 188Re-MAG3-lanreotide and 153Sm-H1ETA-lanreotide. Since the last one has a capacity factor (k") similar to that of 188Re-MAG3, some renal elimination for 153Sm-H1ETA-lanreotide could be expected, which probably would reduce the unnecessary radiation dose to normal tissues. 相似文献
A hybrid organic-inorganic material was prepared from the hydrolytic co-condensation of 3-trimethoxysilylpropylmethacrylate
(MAPTMS) and diphenyldiethoxysilane (DPHDES). The synthesis was performed in three steps: (1) MAPTMS pre-hydrolysis, (2) addition
of DPHDES, and (3) further hydrolysis of the obtained mixture. 29Si nuclear magnetic resonance spectroscopy was used to characterise the structural evolution of the mineral network during
the synthesis. It revealed the catalytic effect of DPHDES on the condensation reaction of silanol groups, initially observed
for pre-hydrolysed MAPTMS. In addition, it was clearly demonstrated that the formation of the highest condensed species of
the aromatic oligomers (D2 species) occurred only in the presence of aliphatic oligomers, which decrease the sterical hindrance about the silicon nuclei. 相似文献