Search results for "computational"
showing 10 items of 5884 documents
The 1-way on-line coupled atmospheric chemistry model system MECO(n) – Part 2: On-line coupling with the Multi-Model-Driver (MMD)
2012
A new, highly flexible model system for the seamless dynamical down-scaling of meteorological and chemical processes from the global to the meso-γ scale is presented. A global model and a cascade of an arbitrary number of limited-area model instances run concurrently in the same parallel environment, in which the coarser grained instances provide the boundary data for the finer grained instances. Thus, disk-space intensive and time consuming intermediate and pre-processing steps are entirely avoided and the time interpolation errors of common off-line nesting approaches are minimised. More specifically, the regional model COSMO of the German Weather Service (DWD) is nested on-line into the …
Theoretical and experimental studies of some main group compounds : from closed shell interactions to singlet diradicals and stable radicals
2012
Acquiring knowledge of different interactions within and between molecules is a fascinating undertaking as it not only deepens our understanding of chemical bonding but also offers insight into electronic structures, molecular properties and the connections between these two. This dissertation combines together three main group chemistry related topics within the aforementioned theme. Research presented in the first third of this dissertation describes wave function and density functional theory studies of weak inter- and intramolecular interactions in pnictogen-based dimers X3Pn···PnX3 (Pn = N-Bi; X = F-I), dithallenes RTlTlR (R = H, Me, tBu, Ph) and octachalcogen dications Ch82+ (Ch = S, …
Optimal recovery of a radiating source with multiple frequencies along one line
2020
We study an inverse problem where an unknown radiating source is observed with collimated detectors along a single line and the medium has a known attenuation. The research is motivated by applications in SPECT and beam hardening. If measurements are carried out with frequencies ranging in an open set, we show that the source density is uniquely determined by these measurements up to averaging over levelsets of the integrated attenuation. This leads to a generalized Laplace transform. We also discuss some numerical approaches and demonstrate the results with several examples.
Design of Reliable and Efficient Banki-Type Turbines
2020
A new shape for the external surface of the Crossflow turbine blades is proposed, which allows for the preservation of hydraulic efficiency in spite of a significant maximum blade thickness providing mechanic robustness and reliability. The final shape of the blades is assessed using an iterative solution for two uncoupled models: a 2D computational fluid dynamic (CFD) and a structural 3D finite element method (FEM) analysis of a single blade. Application of the proposed methodology to the design of a power recovery system (PRS) turbine, a new backpressure Crossflow-type inline turbine for pressure regulation, and energy production in a real Sicilian site follows.
Do Extremely Bent Allenes Exist?
2009
Bent allenes: Theoretical calculations show that extremely bent allenes, cyclic or acyclic, adopt a ground state that only bears a formal relationship to classical allenes. Consequently, five-membered ring allenes favor a carbene-like electronic structure and formally contain a trivalent carbon(II) center. peerReviewed
A quantitative assessment of intraspecific morphological variation in Gahagan bifaces from the southern Caddo area and central Texas
2019
This investigation aggregates intact or reconstructed Gahagan bifaces from the southern Caddo area and central Texas to test the hypothesis that Gahagan biface morphology differs between the regions. The Gahagan bifaces (n = 102) were scanned, then analysed using a novel landmarking protocol and the tools of geometric morphometrics. Results provide a preview of the significant differences in Gahagan biface morphology expressed between the southern Caddo area and central Texas regions. The size discrepancy represents an inversion of current theoretical constructs that posit a decrease in tool size thought to articulate with an increase in distance from the raw material source. It is posited …
Unification of Graphs and Relations in Mizar
2020
Summary A (di)graph without parallel edges can simply be represented by a binary relation of the vertices and on the other hand, any binary relation can be expressed as such a graph. In this article, this correspondence is formalized in the Mizar system [2], based on the formalization of graphs in [6] and relations in [11], [12]. Notably, a new definition of createGraph will be given, taking only a non empty set V and a binary relation E ⊆ V × V to create a (di)graph without parallel edges, which will provide to be very useful in future articles.
Chemical Proteomics-Guided Identification of a Novel Biological Target of the Bioactive Neolignan Magnolol
2019
Understanding the recognition process between bioactive natural products and their specific cellular receptors is of key importance in the drug discovery process. In this outline, some potential targets of Magnolol, a natural bioactive compound, have been identified by proteomic approaches. Among them, Importin-β1 has been considered as the most relevant one. A direct binding between Magnolol and this nuclear chaperone has been confirmed by DARTS and molecular docking, while its influence on Importin-β1 translocation has been evaluated by in vitro assays.
Theoretical ab initio study of the vinylcarbene-CuO complex: application to last step of the propylene partial oxidation mechanism on Cu2O
1988
Abstract Using non-empirical pseudopotentials, we have performed a theoretical study on the last step of the propylene partial oxidation mechanism, the acrolein desorption from the catalyst surface. To represent the catalyst we have used a simplified model of a catalyst active site. We have study the C 3 H 4 CuO complex, analysing the dissociation process of the oxygenated complex from a metallic centre. The results indicate that this complex dissociates into cis - and trans -acrolein and a metal site, in a process without energetic barrier.
Natural acetogenins from annonaceae, synthesis and mechanisms of action
1998
The search concerning Annonaceous acetogenins has increased in the last two years. The goal of the present review is to summarize the knowledge about new isolated acetogenins as well as the advances in synthesis, biological activity and mechanism of action.