Search results for "COMPUTATION"
showing 10 items of 7362 documents
Optimal Heating of an Indoor Swimming Pool
2020
This work presents the derivation of a model for the heating process of the air of a glass dome, where an indoor swimming pool is located in the bottom of the dome. The problem can be reduced from a three dimensional to a two dimensional one. The main goal is the formulation of a proper optimization problem for computing the optimal heating of the air after a given time. For that, the model of the heating process as a partial differential equation is formulated as well as the optimization problem subject to the time-dependent partial differential equation. This yields the optimal heating of the air under the glass dome such that the desired temperature distribution is attained after a given…
On the Modeling of Transcatheter Therapies for the Aortic and Mitral Valves: A Review
2022
Transcatheter aortic valve replacement (TAVR) has become a milestone for the management of aortic stenosis in a growing number of patients who are unfavorable candidates for surgery. With the new generation of transcatheter heart valves (THV), the feasibility of transcatheter mitral valve replacement (TMVR) for degenerated mitral bioprostheses and failed annuloplasty rings has been demonstrated. In this setting, computational simulations are modernizing the preoperative planning of transcatheter heart valve interventions by predicting the outcome of the bioprosthesis interaction with the human host in a patient-specific fashion. However, computational modeling needs to carry out increasingl…
Optimality of Increasing Stability for an Inverse Boundary Value Problem
2021
In this work we study the optimality of increasing stability of the inverse boundary value problem (IBVP) for the Schrödinger equation. The rigorous justification of increasing stability for the IBVP for the Schrödinger equation were established by Isakov [Discrete Contin. Dyn. Syst. Ser. S, 4 (2011), pp. 631--640] and by Isakov et al. [Inverse Problems and Applications, Contemp. Math. 615, American Math Society, Providence, RI, 2014, pp. 131--141]. In [Discrete Contin. Dyn. Syst. Ser. S, 4 (2011), pp. 631--640] and [Inverse Problems and Applications, Contemp. Math. 615, American Math Society, Providence, RI, 2014, pp. 131--141], the authors showed that the stability of this IBVP increases …
Knowledge mining of unstructured information: application to cyber domain
2023
Funding Information: TT, KB, ML and KK acknowledge research project funding from Cyberwatch Finland. AC is the CEO of the company. PJ and AC are founders and partners in the company. KK and ML are on the advisory board of the company. Funding Information: TT, KB, ML and KK acknowledge research project funding from Cyberwatch Finland. TT acknowledges funding from the Vilho, Yrjö and Kalle Väisälä Foundation of the Finnish Academy of Science and Letters. Publisher Copyright: © 2023, The Author(s). Information on cyber-related crimes, incidents, and conflicts is abundantly available in numerous open online sources. However, processing large volumes and streams of data is a challenging task for…
On the physicochemical properties of pyridohelicenes.
2014
A comprehensive study on the physicochemical properties of a series of mono- and diaza[5]helicenes as well as mono- and diaza[6]helicenes is reported. Through the use of both computational and experimental methods, these helically chiral pyridohelicenes with the nitrogen atom(s) in various positions are characterised according to their inversion barriers, protonation constants and redox potentials. By using DFT calculations, kinetic measurements, UV/Vis titrations, cyclic voltammetry and EPR spectroscopy, a self-contained picture of their behaviour under conventional treatment by heat, acids and oxidising/reducing agents is provided.
Gold(I)-catalyzed intermolecular oxyarylation of alkynes: unexpected regiochemistry in the alkylation of arenes.
2009
The reaction between acetylenes and sulfoxides, studied as a test case for gold-catalyzed intermolecular addition, provides the oxyarylation compounds 3 in good yields. Unpredictably, in all cases a single regioisomer arising from the electrophilic aromatic alkylation at the position adjacent to the sulfur atom is obtained instead of the expected Friedel−Crafts regioisomer. A new concerted mechanism based on DFT calculations is proposed to account for the products in this intermolecular gold(I)-catalyzed reaction.
Atomistic Insights into Nitrogen-Cycle Electrochemistry: A Combined DFT and Kinetic Monte Carlo Analysis of NO Electrochemical Reduction on Pt(100)
2017
Electrocatalytic denitrification is a promising technology for the removal of NOx species in groundwater. However, a lack of understanding of the molecular pathways that control the overpotential and product distribution have limited the development of practical electrocatalysts, and additional atomic-level insights are needed to advance this field. Adsorbed NO has been identified as a key intermediate in the NOx electroreduction network, and the elementary steps by which it decomposes to NH4+, N2, NH3OH+, or N2O remain a subject of debate. Herein, we report a combined density functional theory (DFT) and kinetic Monte Carlo (kMC) study of this reaction on Pt(100), a catalytic surface that i…
Oxidative Dehydrogenation of Ethanol on Gold : Combination of Kinetic Experiments and Computation Approach to Unravel the Reaction Mechanism
2021
Abstract Selective alcohol dehydrogenation on heterogeneous catalysts is a key industrial reaction for production of aldehydes, ketones, and carboxylic compounds. Design of catalysts with improved activity and selectivity requires understanding of the reaction mechanism and kinetics. Herein, experiments, density functional theory (DFT) and kinetic modelling were combined to elucidate the mechanism and kinetics of ethanol oxidative dehydrogenation to acetaldehyde on gold catalysts. Catalytic experiments clearly emphasized the role of oxygen in this reaction. Ethanol conversion was rather independent on the gold cluster size. Formation of minor products, acetic acid and ethyl acetate was stru…
Prediction of properties of chiral compounds by molecular topology
1998
Abstract A common assumption in chemistry is that chiral behavior is associated with 3-D geometry. However, chiral information is related to symmetry, which allows the topological handling of chiral atoms by weighted graphs and the calculation of new descriptors that give a weight to the corresponding entry in the main diagonal of the topological matrix. In this study, it is demonstrated that, operating in this way, chiral topological indices are obtained that can differentiate the pharmacological activity between pairs of enantiomers. The 50% inhibitory concentration (IC50) values of the D2 dopamine receptor and the σ receptor for a group of 3-hydroxy phenyl piperidines are specifically pr…
Structure-based evaluation of the resonance interactions and effectiveness of the charge transfer in nitroamines
2011
Structural data for five nitroamines of general formula Me2N–G–NO2 show effectiveness of the ground-state charge transfer to be most and least efficient in N,N-dimethylnitramine and in 4-N,N-dimethylamino-β-nitrostyrene, respectively. Electron-donor power of the amino nitrogen atom in the latter compound is less than that in 4-nitro-β-N,N-dimethylaminostyrene (these two compounds are isomers). Natural population analysis shows that the charge transfer from the amino to the nitro oxygen atoms is most effective in N,N-dimethylnitramine, Me2N–NO2. The nitro oxygen atoms are not the only acceptors of the negative charge lost by the amino nitrogen atom. The nitro group in two substituted nitrobe…