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111.
S.?Tzortzakis G.?Tsaknakis A.?PapayannisEmail author A.A.?Serafetinides 《Applied physics. B, Lasers and optics》2004,79(1):71-75
The stimulated Raman scattering (SRS) beam spatial mode structure is studied in H2 and D2 gases, in a 60 cm-long high-pressure Raman cell, using a pulsed Nd:YAG laser at 266 nm. The conversion efficiencies of the first and second Stokes in H2, D2 and H2/D2 mixtures have been measured precisely in the 1–14 atm range. The SRS beam profiles were recorded for different gas pressures in the high-pressure Raman cell and interesting behaviour is revealed. Homogeneous SRS spatial profiles were obtained only for pressures higher than 7 atm. For lower pressures the profiles are either in the form of a ring or of a more complicated shape. The results are explained in terms of nonlinear self-focusing processes during the pump beam propagation in the Raman cell. Also, from our measurements, a more precise value of the nonlinear index of refraction for the H2 and D2 at 266 nm is proposed. PACS 42.65.Dr; 42.60.Jf; 42.60.Lh; 42.65.Jx 相似文献
112.
K.?Loumponias G.?TsaklidisEmail author 《Methodology and Computing in Applied Probability》2017,19(4):1227-1239
Every attainable structure of a continuous time homogeneous Markov chain (HMC) with n states, or of a closed Markov system with an embedded HMC with n states, or more generally of a Markov system driven by an HMC, is considered as a point-particle of ? n . Then, the motion of the attainable structure corresponds to the motion of the respective point-particle in ? n . Under the assumption that “the motion of every particle at every time point is due to the interaction with its surroundings”, ? n (and equivalently the set of the accosiated attainable structures of the homogeneous Markov system (HMS), or alternatively of the underlying embedded HMC) becomes a continuum. Thus, the evolution of the set of the attainable structures corresponds to the motion of the continuum. In this paper it is shown that the evolution of a three-dimensional HMS (n = 3) or simply of an HMC, can be interpreted through the evolution of a two-dimensional isotropic viscoelastic medium. 相似文献
113.
Let \({\mathbf{H}}^n_{{\mathbb K}}\) denote the symmetric space of rank-1 and of non-compact type and let \(d_{{\mathfrak H}}\) be the Korányi metric defined on its boundary. We prove that if d is a metric on \(\partial {\mathbf{H}}^n_{{\mathbb K}}\) such that all Heisenberg similarities are d-Möbius maps, then under a topological condition d is a constant multiple of a power of \(d_{{\mathfrak H}}\). 相似文献
114.
115.
N.?Kalyvas P.?Liaparinos C.?Michail S.?David G.?Fountos M.?Wójtowicz E.?Zych I.?KandarakisEmail author 《Applied Physics A: Materials Science & Processing》2012,106(1):131-136
Scintillator materials are widely used in X-ray medical imaging detector applications, coupled with available photoreceptors
like radiographic film or photoreceptors suitable for digital imaging like a-Si, charge-coupled devises (CCD), complementary
metal-oxide-semiconductors (CMOS) and GaAs). In addition, scintillators can be utilized in non-medical imaging detectors such
as industrial detectors for non-destructive testing (NDT) and detectors used for security purposes (i.e. airport luggage control).
Image quality and dose burden in the above applications is associated with the amount of optical photons escaping the scintillator
as well as the amount of optical photons captured by the photoreceptor. The former is characterized by the scintillator efficiency
and the latter by the spectral matching between the emission spectrum of the scintillator and the spectral response of the
photoreceptor. Recently, a scintillator material, europium-activated lutetium oxide (Lu2O3:Eu), has shown improved scintillating properties. Lu2O3:Eu samples of compact nanocrystalline non-agglomerated powder were developed in our laboratory using homogeneous precipitation
from a water-toluene solution in the presence of polyvinyl alcohol as a surfactant. In order to test their light-emission
properties, experimental measurements under the excitation of X-ray spectra with X-ray tube voltages between 50 kVp and 140 kVp
were performed. This range of applied voltages is appropriate for X-ray radiology, NDT and security applications. Lu2O3:Eu was evaluated with respect to output yield and spectral compatibility of digital imaging photoreceptors (CCD-based, CMOS-based,
amorphous silicon a:Si flat panels, ES20 and GaAs). High light yield and spectral compatibility increase the performance of
the medical detector and reduce the dose burden to the personnel involved. In addition a theoretical model was used to determine
the values for the Lu2O3:Eu optical photon light propagation parameters. The inverse diffusion length was found to be equal to 33 cm2/g. In addition Lu2O3:Eu was found to match well with several photoreceptors capable of digital imaging (i.e. GaAs). 相似文献
116.
Paraskevi?PouliEmail author Mohamed?Oujja Marta?Castillejo 《Applied Physics A: Materials Science & Processing》2012,106(2):447-464
In the last twenty years lasers have acquired an important role in the study and the preservation of Cultural Heritage (CH)
objects and Monuments, as they have effectively illuminated a number of complex diagnostic and restoration problems. Their
unique properties have enabled their use in a wide range of conservation applications, since they ensure interventions with
precise control, material selectivity and immediate feedback. 相似文献
117.
Alexey?A.?BasharinEmail author Nikolay?L.?Menshikh 《Applied Physics A: Materials Science & Processing》2012,106(3):517-522
A modified planar waveguide made of a metamaterial with negative permittivity and permeability has been considered. The modification
of the waveguide by the introduction of an air channel qualitatively changes its dispersion characteristics due to the appearance
of an ultraslow mode. The fields and properties of this mode have been investigated. The mode has been shown to be similar
to a surface plasmon. In addition, it has been shown that the plasmons can propagate in subwavelength waveguides. Such ultraslow
plasmons can be used in plasmonics, microwave and accelerator techniques. 相似文献
118.
Vivi?TornariEmail author Elsa?Tsiranidou Eirini?Bernikola 《Applied Physics A: Materials Science & Processing》2012,106(2):397-410
The paper is directed to all classes of optical inspection technologies that are causing a fringe pattern like output, such
as interferometry, fringe projection, holography, speckle techniques. The explanations given here are also valid for incoherent
fringe projection, moire, and short-coherent techniques, which are producing fringe-like output correlated with the surface
structure and the surface change, respectively. 相似文献
119.
Fogassy E Nógrádi M Kozma D Egri G Pálovics E Kiss V 《Organic & biomolecular chemistry》2006,4(16):3011-3030
Despite the large number of elaborate enantioselective syntheses for the preparation of a single enantiomer to achieve industrial and scientific goals, the separation and purification of enantiomers (components of racemic compounds) is also necessary. Hence, we present the most often used thought-provoking modern methods based on momentous recognitions (e.g. spontaneous resolution, induced crystallization, resolution by formation of diastereomers, resolution by formation of non-covalent diastereomers, resolution by diastereomeric salt formation, resolution by diastereomeric complex formation, "half equivalent" methods of resolution, separation by crystallization, separation by distillation, separation by supercritical fluid extraction, resolution with mixtures of resolving agents, resolution with a derivative of the target compound, enantioselective chromatography, resolution by formation of covalent diastereomers, resolution by substrate selective reaction, kinetic resolution without enzymes, kinetic resolution by enzyme catalysis, hydrolytic and redox enzymes, kinetic and thermodynamic control, resolutions combined with 2nd order asymmetric transformations, enrichment of partially resolved mixtures, role of the solvent and methods of optimization in the separation of diastereoisomers, non-linear effects and selected examples of resolution on an industrial scale). 相似文献
120.
Ioanna?MakarouniEmail author John?Psarras Eleftherios?Siskos 《Annals of Operations Research》2015,225(1):45-63
In this paper we develop an interactive decision analysis approach to treat a large scale bicriterion integer programming problem, addressing a real world assembly line scheduling problem of a manufacturing company. This company receives periodically a set of orders for the production of specific items (jobs) through a number of specialised production (assembly) lines. The paper presents a non compensatory approach based on an interactive implementation of the ε-constraint method that enables the decision maker to achieve a satisfactory goal for each objective separately. In fact, the method generates and evaluates a large number of non dominated solutions that constitute a representative sample of the criteria ranges. The experience with a specific numerical example shows the efficiency and usefulness of the proposed model in solving large scale bicriterion industrial integer programming problems, highlighting at the same time the modelling limitations. 相似文献