Search results for "Coupled"
showing 10 items of 742 documents
A posteriori estimates for a coupled piezoelectric model
2017
Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch)
Evaluation of performance of a hybrid electro-optic directional coupler and a Mach–Zehnder switch
2017
The efficiency of an electro-optic (EO) directional coupler (DC) and a Mach–Zehnder (MZ) switch is discussed. The specific designs employ a passive waveguide core and an EO cladding. The performance of a DC switch was evaluated by numerical methods, namely coupled mode theory (CMT), eigenmode expansion (EME) method, and beam envelope method. Using the CMT and EME methods, it is shown that in the DC with a passive waveguide core and EO cladding at certain waveguide parameters the switching effect does not take place. The effect is demonstrated for the first time and suggests that careful optimization of the DC switch should be done before experimental realization of the device. The efficienc…
Grand canonical ensemble approach to electrochemical thermodynamics, kinetics, and model Hamiltonians
2021
The unique feature of electrochemistry is the ability to control reaction thermodynamics and kinetics by the application of electrode potential. Recently, theoretical methods and computational approaches within the grand canonical ensemble (GCE) have enabled to explicitly include and control the electrode potential in first principles calculations. In this review, recent advances and future promises of GCE density functional theory and rate theory are discussed. Particular focus is devoted to considering how the GCE methods either by themselves or combined with model Hamiltonians can be used to address intricate phenomena such as solvent/electrolyte effects and nuclear quantum effects to pr…
Accurate Nonlinear Optical Properties for Small Molecules
2006
During the last decade it became possible to calculate by quantum chemical ab initio methods not only static but also frequency-dependent properties with high accuracy. Today, the most important tools for such calculations are coupled cluster response methods in combination with systematic hierarchies of correlation consistent basis sets. Coupled cluster response methods combine a computationally efficient treatment of electron correlation with a qualitatively correct pole structure and frequency dispersion of the response functions. Both are improved systematically within a hierarchy of coupled cluster models. The present contribution reviews recent advances in the highly accurate calculat…
Communication: The performance of non-iterative coupled cluster quadruples models
2015
We compare the numerical performance of various non-iterative coupled cluster (CC) quadruples models. The results collectively show how approaches that attempt to correct the CC singles and doubles energy for the combined effect of triple and quadruple excitations all fail at recovering the correlation energy of the full CC singles, doubles, triples, and quadruples (CCSDTQ) model to within sufficient accuracy. Such a level of accuracy is only achieved by models that make corrections to the full CC singles, doubles, and triples (CCSDT) energy for the isolated effect of quadruple excitations of which the CCSDT(Q–3) and CCSDT(Q–4) models of the Lagrangian-based CCSDT(Q–n) perturbation series a…
Imbalance of expression of bFGF and PK1 is associated with defective maturation and antenatal placental insufficiency.
2013
Abstract Objective Defective placental maturation is associated with restricted functional capacity and adverse perinatal fetal outcomes. The aim of the study was a comparative analysis of the role of mRNA expression of various angiogenic factors in placental maturation defects. Study design We examined the mRNA expression patterns of prokineticin 1 (PK1), its receptors (PKRs), basic-fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) in tissue from third-trimester placentae that exhibited delayed or accelerated villous maturation. Results The expression of PK1 and PKR2 was elevated in placental tissue exhibiting accelerated maturati…
Polarizability and optical rotation calculated from the approximate coupled cluster singles and doubles CC2 linear response theory using cholesky dec…
2004
A new implementation of the approximate coupled cluster singles and doubles CC2 linear response model using Cholesky decomposition of the two-electron integrals is presented. Significantly reducing storage demands and computational effort without sacrificing accuracy compared to the conventional model, the algorithm is well suited for large-scale applications. Extensive basis set convergence studies are presented for the static and frequency-dependent electric dipole polarizability of benzene and C60, and for the optical rotation of CNOFH2 and (−)-trans-cyclooctene (TCO). The origin-dependence of the optical rotation is calculated and shown to persist for CC2 even at basis set convergence. …
Damage monitoring on carbonate stones: Field exposure tests contributing to pollution impact evaluation in two Italian sites
2017
During the last decades, many studies have been carried out on environmental monitoring in specific sites aiming at their protection and conservation; however, researches focused on the direct implications, in terms of quantitative evaluation of stone deterioration, of these monitoring actions are still scarce. This experimental work aims at monitoring the degradation processes affecting historical buildings constituted by carbonate stones. Specifically, specimens of Carrara marble and two limestones largely used in the Sicilian Baroque architecture, namely Noto and Comiso stones, were exposed outdoor in two Italian sites (Catania and Palermo), which are characterized by different environme…
Inorganic geochemistry of roadway dust from the metropolitan area of Palermo, Italy
2003
Inorganic matter from roadway dust collected in the urban area of Palermo, Italy, was analysed to identify the chemical elements introduced into the environment as a result of human activities. Metals of environmental concern exhibit very high enrichment factors, which in some cases exceed 100. Metal size distribution indicates that Pd, Pt, Au, Sb, Zn, S, Ni, V, Mo and Cr substantially accumulate in the finest particles, whereas Pb, Br, As, Cu, Ag and Ba are almost independent of the size fraction. SEM/EDS analyses revealed that some individual particles contain clusters of foreign particles (<10 μm) made up of Fe-Ni, Cr-Ni or Fe alone, typical of the abrasion of stainless steel. Others are…
THE MATHEMATICAL MODELING OF METALS CONTENT IN PEAT
2015
Metals deposition in peat can aid to evaluate impact of atmospheric or wastewaters pollution and thus can be a good indicator of recent and historical changes in the pollution loading. For peat using in agriculture, industrial, heat production etc. knowledge of peat metals content is important. Experimental determination of metals in peat is very long and expensive work. Using experimental data the mathematical model for calculation of concentrations of metals in different points for different layers is developed. The values of the metals (Ca, Mg, Fe, Sr, Cu, Zn, Mn, Pb, Cr, Ni, Se, Co, Cd, V, Mo) concentrations in different layers in peat taken from Knavu peat bog from four sites are deter…