Search results for "element"
showing 10 items of 13601 documents
Paschen β line shape studies in low-temperature plasmas
2003
Line shape calculations and measurements of the Paschen β line of hydrogen (λ=12818 Å) are reported. Measurements were performed at electron densities of the plasma between 1015 cm-3 and 1016 cm-3. A wall-stabilized arc operated at atmospheric pressure in a helium-hydrogen gas mixture was applied as the excitation source. The radiation of the plasma, originating from nearly homogeneous plasma layers, in the end-on direction, was analyzed. A grating spectrometer equipped with a CCD detector was used for the radiation detection. The measured line profiles are compared with results of available experimental and theoretical Stark broadening data e.g. based on simulation techniques, applied also…
Optical study of gallium and nitrogen polarity layers of GaN grown on sapphire
2003
A confocal Raman spectroscopic study was carried out on either side of an intentionally grown GaN inversion domain boundary between a pair of strips with opposite (Ga- or N-) polarity. It is shown that the Raman spectra on the N-polarity side displays an A1(TO) mode, prohibited by symmetry considerations, meanwhile on Ga-polarity material this peak is absent, indicating a lower density of defects present in this region. The Raman spectra reveal that in the lateral direction, the change in structural quality accross the inversion domain boundary is rather continuous and extends along 4 ± 1 μm. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Sākumskolas skolēnu nūjošanas pamatelementu apguves sekmēšana veselības un fiziskās aktivitātes mācību jomā
2022
Darba nosaukumus: sākumskolas skolēnu nūjošanas pamatelementu apguves sekmēšana veselības un fiziskās aktivitātes mācību jomā. Darba autore: Linda Eizenbārde. Darbs sastāv no divām daļām – teorētiskās un empīriskās daļas. Teorētiskajā daļā tiek analizēta pedagoģiskā un zinātniskās literatūra un dažādu autoru atziņas par sākumskolas skolēnu fizisko un psiholoģisko attīstību, nūjošanas ietekmi uz skolēna fizisko attīstību, kā arī nūjošanas pamatelementu apguves iespējām sporta stundā. Empīriskajā daļā tiek pētīta sākumskolas skolēnu nūjošanas pamatelementu apguve veselības un sporta stundā. Tiek veikts skolēnu novērojums, lai noskaidrotu fizisko sagatavotību pirms uzsākt nūjošanas pamatelemen…
Rakstītprasmes veicināšana sākumskolas skolēniem ar mācīšanās traucējumiem
2019
Diplomdarba autore Linda Spalva. Šobrīd autore studē Latvijas Universitātē, studiju programmā speciālās izglītības skolotājs/skolotājs logopēds. Paralēli studijām autore apmeklē dažādus kursus gan logopēdijā, gan speciālajā pedagoģijā. Kopš 2018.gada sākuma strādā vispārizglītojošā skolā par speciālo pedagogu. Diplomdarba tēma – Rakstītprasmes veicināšana sākumskolas skolēniem ar mācīšanās traucējumiem. Rakstītprasme ir viena no dzīves pamatprasmēm, ko skolēns apgūst skolā, tādēļ ļoti būtiski to izkopt un pilnveidot. Arvien biežāk nākas saskarties ar skolēniem, kuriem ir dažāda veida traucējumi, tādēļ nepieciešams noteikt traucējuma veidu un sniegt bērnam palīdzību. Diplomdarba mērķis ir te…
A New Augmented Lagrangian Approach for $L^1$-mean Curvature Image Denoising
2015
Variational methods are commonly used to solve noise removal problems. In this paper, we present an augmented Lagrangian-based approach that uses a discrete form of the L1-norm of the mean curvature of the graph of the image as a regularizer, discretization being achieved via a finite element method. When a particular alternating direction method of multipliers is applied to the solution of the resulting saddle-point problem, this solution reduces to an iterative sequential solution of four subproblems. These subproblems are solved using Newton’s method, the conjugate gradient method, and a partial solution variant of the cyclic reduction method. The approach considered here differs from ex…
LOCAL CONTROL OF SOUND IN STOCHASTIC DOMAINS BASED ON FINITE ELEMENT MODELS
2011
A numerical method for optimizing the local control of sound in a stochastic domain is developed. A three-dimensional enclosed acoustic space, for example, a cabin with acoustic actuators in given locations is modeled using the finite element method in the frequency domain. The optimal local noise control signals minimizing the least square of the pressure field in the silent region are given by the solution of a quadratic optimization problem. The developed method computes a robust local noise control in the presence of randomly varying parameters such as variations in the acoustic space. Numerical examples consider the noise experienced by a vehicle driver with a varying posture. In a mod…
Elementary Math to Close the Digital Skills Gap
2018
All-encompassing digitalization and the digital skills gap pressure the current school system to change. Accordingly, to ’digi-jump’, the Finnish National Curriculum 2014 (FNC-2014) adds programming to K-12 math. However, we claim that the anticipated addition remains too vague and subtle. Instead, we should take into account education recommendations set by computer science organizations, such as ACM, and define clear learning targets for programming. Correspondingly, the whole math syllabus should be critically viewed in the light of these changes and the feedback collected from SW professionals and educators. These findings reveal an imbalance between supply and demand, i.e., what is ove…
Optical Properties of Monolayer-Protected Aluminum Clusters: Time-Dependent Density Functional Theory Study
2015
We examine the electronic and optical properties of experimentally known monolayer-protected aluminum clusters Al4(C5H5)4, Al50(C5Me5)12, and Al69(N(SiMe3)2)183– using time-dependent density functional theory. By comparing Al4(C5H5)4 and the theoretical Al4(N(SiMe3)2)4 cluster, we observe significant changes in the optical absorption spectra caused by different hybridization between metal core and ligands. Using these initial observations, we explain the calculated spectra of Al50(C5Me5)12 and Al69(N(SiMe3)2)183–. Al50(C5Me5)12 shows a structured spectrum with clear regions of low-intensity core-to-core transitions followed by high-intensity ligand-to-core transitions due to its high symmet…
One-pot synthesis and characterization of subnanometre-size benzotriazolate protected copper clusters
2012
A simple one-pot method for the preparation of subnanometre-size benzotriazolate (BTA) protected copper clusters, Cu(n)BTA(m), is reported. The clusters were analyzed by optical and infrared spectroscopy, mass spectrometry and transmission electron microscopy together with computational methods. We suggest a structural motif where the copper core of the Cu(n)BTA(m) clusters is protected by BTA-Cu(i)-BTA units.
The electronic structure of Ge9[Si(SiMe3)3]3-: a superantiatom complex.
2012
We report on the electronic structure of Ge(9)[Si(SiMe(3))(3)](3)(-). Systematic density functional theory analysis of the electronic shell structure of the cluster and its derivatives reveals that the Ge(9)[Si(SiMe(3))(3)](3)(-) and its neutral counterpart have electronic shells that can be explained using the superatom model. The ligand-core interaction of these complexes is distinctly different from previously identified gold, gallium, and aluminium superatom complexes, indicating an electron-donating rather than electron-withdrawing ligand. We modify the electron-counting rule for this case and introduce a simple picture for superatom and superantiatom complexes. Discussions comparing s…