Search results for "intensity"
showing 10 items of 1091 documents
Observations of Forbush Decreases of cosmic ray electrons and positrons with the Dark Matter Particle Explorer
2021
The Forbush Decrease (FD) represents the rapid decrease of the intensities of charged particles accompanied with the coronal mass ejections (CMEs) or high-speed streams from coronal holes. It has been mainly explored with ground-based neutron monitors network which indirectly measure the integrated intensities of all species of cosmic rays by counting secondary neutrons produced from interaction between atmosphere atoms and cosmic rays. The space-based experiments can resolve the species of particles but the energy ranges are limited by the relative small acceptances except for the most abundant particles like protons and helium. Therefore, the FD of cosmic ray electrons and positrons have …
Background subtraction and peak search from threefold gamma event data
1990
Abstract A method for subtracting background from triple-coincidence γ events is presented. In our data set it was used to remove 40% of the noise without affecting photopeaks with intensity of >18 counts. An example of performance of Ward's clustering algorithm applied to three-dimensional photopeak searching is also presented. Several standard clustering algorithms were found to be applicable only to background-subtracted data.
Negative U‐properties of the oxygen‐vacancy in ZnO
2006
It is shown that the intensity of the oxygen vacancy (VO) related emission in ZnO at 2.45 eV correlates to the concentration of the donor level E4. E4 is located 530 meV below the conduction band and attributed to the VO0/++ recharging. Deep level transient spectroscopy (DLTS) experiments with optical excitation locate the VO2+/+ level position 140 meV below the conduction band and give evidence for the “negative- U” properties of the oxygen vacancies in ZnO. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Improved technique for quantitative EDXRF analysis of powdered plant samples
1998
An improved technique for energy-dispersive x-ray fluorescence analysis of powdered plant samples is presented. It is based on the use of a special rotating and moveable sample holder (RMSH). This sample holder provides both controlled rotation and lateral transfer movements of the sample while a measurement is carried out, consequently simulating homogeneous excitation conditions over the sample. In this way it compensates for effects caused by the typical inhomogeneous distribution of intensity within the x-ray beam exciting the elements in the sample. The sample consists of powdered dry plant material deposited in an easy way on an adhesive tape, providing a stable layer of plant particl…
Tīklenes attēlu analīze diabētiskās retinopātijas radīto tīklenes izmaiņu detektēšanai
2022
Bakalaura darbs ir uzrakstīts angļu valodā uz 42 lappusēm. Tas satur 32 attēlus, 2 tabulas un 59 atsauces uz literatūras avotiem. Darba mērķis bija pārbaudīt, vai pastāv atšķirība starp vidējo pikseļu intensitāti fundusa attēlā, kurā redzama vesela tīklene, un attēlu ar diabētisku retinopātiju. Attēli tika ņemti no divām datu bāzēm, kurās kopumā bija 127 attēli bez patologijam un 129 attēli ar diabētiskās retinopātijas klātbūtni. Attēlu analīzei tika izmantota programma MATLAB. Pētījuma rezultāti parādīja, ka zilajam kanālam ir būtiska atšķirība, bet sarkanajam un zaļajam kanālam nav. Ir jāveic vairāk pētījumu, lai secinātu, vai ir būtiskas atšķirības pikseļu intensitātē veseliem un diabēti…
An Analysis of Earthquakes Clustering Based on a Second-Order Diagnostic Approach
2009
A diagnostic method for space–time point process is here introduced and applied to seismic data of a fixed area of Japan. Nonparametric methods are used to estimate the intensity function of a particular space–time point process and on the basis of the proposed diagnostic method, second-order features of data are analyzed: this approach seems to be useful to interpret space–time variations of the observed seismic activity and to focus on its clustering features.
Femtosecond laser induced breakdown spectroscopy of air–methane mixtures
2013
Abstract Femtosecond laser pulses are used in order to induce dielectric breakdown in gaseous mixtures, namely in some reactive air–methane mixtures. The light emitted from the laser induced plasma was analyzed while the main emission features are identified and assigned. From the analysis of the emission spectra, a linear relationship was found to hold between the intensity of some spectral features and methane content. Finally, the use of femtosecond laser induced breakdown as a tool for the in situ determination of the composition of gaseous mixtures (e.g., equivalence ratio) is also discussed.
Ambient-temperature high-pressure-induced ferroelectric phase transition in CaMnTi2O6
2017
The ferroelectric to paraelectric phase transition of multiferroic ${\mathrm{CaMnTi}}_{2}{\mathrm{O}}_{6}$ has been investigated at high pressures and ambient temperature by second-harmonic generation (SHG), Raman spectroscopy, and powder and single-crystal x-ray diffraction. We have found that ${\mathrm{CaMnTi}}_{2}{\mathrm{O}}_{6}$ undergoes a pressure-induced structural phase transition ($P{4}_{2}mc\ensuremath{\rightarrow}P{4}_{2}/nmc$) at $\ensuremath{\sim}7\phantom{\rule{0.16em}{0ex}}\mathrm{GPa}$ to the same paraelectric structure found at ambient pressure and ${T}_{c}=630\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. The continuous linear decrease of the SHG intensity that disappears at 7 …
X-Ray diffraction diagram evolution of a BaTiO3ceramic under an electric field
1994
Abstract The X-ray diffraction diagrams of a coarse grained pure BaTiO3 ceramic have been recorded as a function of the applied electric D.C. field. This field was perpendicular to the X-ray incoming surface. The experimental device used allows to record diffraction diagrams while the electric field step by step increases. The intensity ratio of the 002 line over the 200 line increases with the applied electric field. The evolution of the X-ray diffraction line intensities is in correlation with the first polarization curve of the ferroelectric ceramic. These results evidence a contribution of the 90° ferroelectric domains pattern to the X-ray diffraction diagram of BaTiO3.
<title>Sub-bandgap light hologram recording in amorphous chalcogenides</title>
2006
Sub-bandgap light recording (SBLR) of holograms is studied basing on the experiments in a-As2S3 films and literature data. Holographic grating recording with focused (light intensity I = 14 - 124 W/cm2 ) and unfocused (I = 0.50 - 0.78 W/cm2) 632.8 nm He-Ne laser sub-bandgap light in non-annealed and annealed a-As2S3 films has been experimentally studied. The focused light recording is found to be much more efficient (diffraction efficiency up to 14.9%, specific recording energy down to 216 J/(cm2%)) than the unfocused light recording (0.11%, 72400 J/(cm2%)). Some other properties are also different. The focused light recording is explained by the photothermally stimulated relaxational struc…