Numerical simulation of resonance structures with FDTD algorithms based on GPU B-CALM and CPU Meep

Simulation time is one of the bottlenecks of finite-difference-time-domain (FDTD) method. There are several ways of reducing the simulation time, one of which is the usage of graphical processing unit (GPU). Thus in this paper we present comparison between two free FDTD software packages. One is based on central processing unit and other is based on GPU. The 3D test structures we analyzed were metallic rectangular cavity resonator and microring resonator based refractive index sensor. The comparison between two FDTD software packages is made with regard to simulation time and numerical accuracy. It is shown that both packages agree in numerical results and that GPU based FDTD implementation performs same simulation up to 18 times faster.     

The Second Lacuna in the Orders of Movement Groups of the Spaces U n

We prove the nonexistence of symmetrically linearly connected spaces of hyperplane elements admitting a movement group G _r with n ² - n + 2 r n² - 1, n 5.     

Tribochemical and thermal activation of α-c2s hydrate as precursor for cementitious binders

Co-pyrolysis characteristics of white pine and sub-bituminous coal blend were studied by thermogravimetric analysis (TG) and in a free fall reactor. The pyrolysis behavior of the blends at various biomass blending ratios was compared with that of the individual coal and biomass. The results from TG indicate that the interactions between the blends present an inhibitive effect on thermal decomposition, resulting in higher than expected char yields. In the free fall reactor, a positive synergy effect on tar production was observed under the higher biomass blending ratio. Moreover, the compositions of the gaseous products from the blends are not all in accordance with those of their parent fuels. The observed synergetic effects might be due to char-coal interactions in TG, while gas-coal interactions are preferred in free fall reactor.     

Synthesis of methyl esters of 5-amino-4-(substituted amino)-2-methylthio-7H-pyrrolo[2,3d]-pyrimidine-6-carboxylic acids

The optimum route for the synthesis of methyl esters of N-[(4-substituted amino)-5-cyano-2-methylthiopyrimidin-6-yl]amino acids (which are starting materials for preparing the methyl esters of the corresponding 5-amino-4-(substituted amino)pyrrolo[2,3-d]pyrimidine-6-carboxylic acids) is via subsequent reactions of 4,6-dichloro-2-methylthiopyrimidine-5-carbonitrile with amines and methyl glycinate. In some examples, the reaction of methyl N-(4-chloro-2-methylthio-6-pyrimidinyl)aminoacetate with amines occurs to give the corresponding acid amides. The previously unknown synthesized derivatives of pyrimidin-6-yl amino acids and 4,5-diaminopyrrolo[2,3-d]pyrimidine- 6-carboxylic acids possess fungicidal properties.Vilnius University, Vilnius 2006, Lithuania. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No 7, pp. 955–961, July, 2000.