Mechanism of Grignard reagent formation. Comparisons of D-model calculations with experimental product yields

1989 ◽  
Vol 111 (1) ◽  
pp. 241-250 ◽  
Author(s):  
John F. Garst ◽  
Brian L. Swift
Keyword(s):  
Grignard Reagent ◽  
Model Calculations ◽  
Product Yields ◽  
D Model

scholarly journals Three-Dimensional Modelling of EUVE Observations of the Io Plasma Torus

1996 ◽  
Vol 152 ◽  
pp. 457-464
Author(s):  
N. Thomas ◽  
D.E. Innes ◽  
R. Lieu
Keyword(s):  
Three Dimensional ◽  
Emission Lines ◽  
Shift Parameter ◽  
Model Calculations ◽  
Euv Emission ◽  
First Results ◽  
Plasma Torus ◽  
Io Plasma Torus ◽  
Semi Empirical ◽  
D Model

First results from a 3-D model of EUVE observations of the Io Plasma Torus are reported. The semi-empirical model calculations follow a method previously used to describe visible and near-UV emissions. The extension to EUV wavelengths is described. Several EUV emissions have been successfully modelled although some discrepancies remain at this stage. Most EUV emissions peak at a jovicentric distance of ≈ 5.8 RJ. The observed dawn-dusk asymmetry of the torus was well fitted with a shift parameter (ϵ) of 0.03. The modelling also indicates that optical depth effects need to be considered for several EUV emission lines.

Magnetotelluric tensor decomposition: Part I, Theory for a basic procedure

Geophysics ◽  
1998 ◽  
Vol 63 (6) ◽  
pp. 1885-1897 ◽  
Author(s):  
F. E. M. (Ted) Lilley
Keyword(s):  
Pure Shear ◽  
General Theorem ◽  
Tensor Decomposition ◽  
Impedance Tensor ◽  
Model Calculations ◽  
Tensor Decompositions ◽  
The Real ◽  
Mohr Circle ◽  
Basic Procedure ◽  
D Model

The problem of expressing a general 3-D magnetotelluric (MT) impedance tensor in the form of a 2-D tensor that has been distorted in some way is addressed first in terms of a general theorem. This theorem shows that when the real and quadrature parts of a tensor are analyzed separately as distinct matrices, all that is necessary to make a matrix with 2-D characteristics from one with 3-D characteristics is to allow the electric and magnetic observing axes to rotate independently. The process is then examined in terms of the operations of twist and pure shear (“split”) on such matrices. Both of two basic sequences of split after twist, and twist after split, produce a typical 3-D matrix from one initially 1-D, with the parameters of split contributing 2-D characteristics to the final matrix. Taken in reverse, these sequences offer two basic paths for the decomposition of a 3-D matrix, and are seen to be linked to the initial theorem. The various operations on matrices are expressed diagrammatically using the Mohr circle construction, of which it is demonstrated two types are possible. Mohr circles of an observed MT tensor display all the information held by the tensor, and the two types of circle construction respectively make clear whether particular data are well suited to modeling by either split after twist, or twist after split. Generally, tensor decompositions may be displayed by charting their progress in Mohr space. The Mohr construction also displays the invariants of a tensor and shows that tensor decomposition can be viewed as a process of determining an appropriate set of invariants. An expectation that the origin of axes should be outside every circle categorizes as irregular any tensors which, in either the real or quadrature part, do not satisfy a [Formula: see text] criterion. The theory of the present paper applies equally to procedures for distorting 1-D and 2-D model calculations for the purpose of matching observed 3-D data.

scholarly journals Attenuation of global ultraviolet and visible irradiance over Greece during the total solar eclipse of 29 March 2006

2007 ◽  
Vol 7 (23) ◽  
pp. 5959-5969 ◽  
Author(s):  
A. Kazantzidis ◽  
A. F. Bais ◽  
C. Emde ◽  
S. Kazadzis ◽  
C. S. Zerefos
Keyword(s):  
Solar Eclipse ◽  
Total Solar Eclipse ◽  
Model Calculations ◽  
Visible Part ◽  
Comparison Results ◽  
Close Proximity ◽  
Limb Darkening ◽  
First Time ◽  
D Model ◽  
Greek Island

Abstract. The variability of ultraviolet and photosynthetically active radiation (PAR) during the total solar eclipse of 29 March 2006 was examined in this study. The measurements from NILU-UV multichannel radiometers at 7 stations of the Greek UV Network were used, where the maximum eclipse percentage ranged from 73.1% to 94.8%. In addition, an extra instrument was established at a remote Greek island, Kastelorizo, which was within the Moon's umbral shadow. The reduction of irradiance at 305 and 312 nm relative to non-eclipse conditions at all sites was almost 1.5 times more than the corresponding decrease in the UVA and visible part of the spectrum and reached 98% for eclipse percentage equal to 94%. The availability of several instruments in close proximity to the path of the umbral shadow provided a challenging test for the models. The measured changes in UV and visible irradiance were compared with 1-D model calculations accounting for the limb darkening effect. The agreement between measurements and modeled values at all sites is within 3% for eclipse percentages of less than 30% and becomes worse as the eclipse progresses. The 1-D model reproduced the spectral effect of the eclipse in UVA and PAR wavelength regions within 3% for eclipse percentages up to 50%, but only the half of the observed change was captured as the eclipse progressed. At three sites, where the eclipse maximum was more than 94%, the measured irradiance at 305 nm for eclipse percentages of more than 85% decreased with slower rates than for longer wavelengths. As a result, the total ozone values, derived from the 305/320 nm ratios, apparently decreased significantly for high eclipse percentages. The effect is similar at all three sites, but the interpretation of this observation remains a challenge. Comparison results with 3-D model calculations shortly before, during and shortly after totality were performed for the first time and revealed an agreement with measurements within 20% in the UV-A region. However, the modeled estimates of irradiance at 312 nm are three times lower than measured values.

scholarly journals Evidence for an unidentified non-photochemical ground-level source of formaldehyde in the Po Valley with potential implications for ozone production

2015 ◽  
Vol 15 (3) ◽  
pp. 1289-1298 ◽  
Author(s):  
J. Kaiser ◽  
G. M. Wolfe ◽  
B. Bohn ◽  
S. Broch ◽  
H. Fuchs ◽  
...  
Keyword(s):  
Agricultural Land ◽  
Ground Level ◽  
Early Morning ◽  
Oxidation Products ◽  
Ozone Production ◽  
Model Calculations ◽  
Po Valley ◽  
International Regulations ◽  
Convective Mixed Layer ◽  
D Model

Abstract. Ozone concentrations in the Po Valley of northern Italy often exceed international regulations. As both a source of radicals and an intermediate in the oxidation of most volatile organic compounds (VOCs), formaldehyde (HCHO) is a useful tracer for the oxidative processing of hydrocarbons that leads to ozone production. We investigate the sources of HCHO in the Po Valley using vertical profile measurements acquired from the airship Zeppelin NT over an agricultural region during the PEGASOS 2012 campaign. Using a 1-D model, the total VOC oxidation rate is examined and discussed in the context of formaldehyde and ozone production in the early morning. While model and measurement discrepancies in OH reactivity are small (on average 3.4 ± 13%), HCHO concentrations are underestimated by as much as 1.5 ppb (45%) in the convective mixed layer. A similar underestimate in HCHO was seen in the 2002–2003 FORMAT Po Valley measurements, though the additional source of HCHO was not identified. Oxidation of unmeasured VOC precursors cannot explain the missing HCHO source, as measured OH reactivity is explained by measured VOCs and their calculated oxidation products. We conclude that local direct emissions from agricultural land are the most likely source of missing HCHO. Model calculations demonstrate that radicals from degradation of this non-photochemical HCHO source increase model ozone production rates by as much as 0.6 ppb h−1 (12%) before noon.

Experimental data vs. 3-D model calculations of HFCVD processes: correlations and discrepancies

2001 ◽  
Vol 10 (3-7) ◽  
pp. 364-369 ◽  
Author(s):  
Yu.A. Mankelevich ◽  
N.V. Suetin ◽  
M.N.R. Ashfold ◽  
J.A. Smith ◽  
E. Cameron
Keyword(s):  
Experimental Data ◽  
Model Calculations ◽  
D Model

scholarly journals Evidence for an unidentified ground-level source of formaldehyde in the Po Valley with potential implications for ozone production

2014 ◽  
Vol 14 (18) ◽  
pp. 25139-25165
Author(s):  
J. Kaiser ◽  
G. M. Wolfe ◽  
B. Bohn ◽  
S. Broch ◽  
H. Fuchs ◽  
...  
Keyword(s):  
Agricultural Land ◽  
Ground Level ◽  
Early Morning ◽  
Oxidation Products ◽  
Ozone Production ◽  
Model Calculations ◽  
Po Valley ◽  
International Regulations ◽  
Convective Mixed Layer ◽  
D Model

Abstract. Ozone concentrations in the Po Valley of Northern Italy often exceed international regulations. As both a source of radicals and an intermediate in the oxidation of most volatile organic compounds (VOCs), formaldehyde (HCHO) is a useful tracer for the oxidative processing of hydrocarbons that leads to ozone production. We investigate the sources of HCHO in the Po Valley using vertical profile measurements acquired from the airship Zeppelin NT over an agricultural region during the PEGASOS 2012 campaign. Using a 1-D model, the total VOC oxidation rate is examined and discussed in the context of formaldehyde and ozone production in the early morning. While model and measurement discrepancies in OH reactivity are small (on average 3.4±11%), HCHO concentrations are underestimated by as much as 1.5 ppb (45%) in the convective mixed layer. A similar underestimate in HCHO was seen in the 2002–2003 FORMAT Po-Valley measurements, though the additional source of HCHO was not identified. Oxidation of unmeasured VOC precursors cannot explain the missing HCHO source, as measured OH reactivity is explained by measured VOCs and their calculated oxidation products. We conclude that local direct emissions from agricultural land are the most likely source of missing HCHO. Model calculations demonstrate that radicals from degradation of this non-photochemical HCHO source increase model ozone production rates by as much as 0.7 ppb h−1 (10%) before noon.

scholarly journals Activation cross sections of gamma-emitters produced in deuteron induced reactions on $${}^{{209}}$$Bi up to 50 MeV

2021 ◽  
Vol 57 (7) ◽  
Author(s):  
F. Tárkányi ◽  
S. Takács ◽  
F. Ditrói ◽  
Z. Szűcs ◽  
K. Brezovcsik ◽  
...  
Keyword(s):  
Cross Sections ◽  
Thick Target ◽  
Activation Technique ◽  
Model Calculations ◽  
Decay Products ◽  
Foil Activation ◽  
On Line ◽  
Stacked Foil Activation Technique ◽  
D Model ◽  
Activation Cross Sections

AbstractDeuteron induced reactions on natural bismuth targets were investigated with the stacked foil activation technique up to 50 MeV. Excitation functions for the reactions $$^{\mathrm {209}}$$ 209 Bi(d,xn)$$^{\mathrm {207,206,205}}$$ 207 , 206 , 205 Po, Bi(d,x)$$^{\mathrm {207,205}}$$ 207 , 205 Bi and $$^{\mathrm {209}}$$ 209 Bi(d,x)$$^{\mathrm {203}}$$ 203 Pb obtained from gamma-spectra of decay products were compared with the results of our ALICE-D and EMPIRE-D model calculations, with the result of TALYS code taken from TENDL-2019 on-line library and the results of the only measurement performed earlier. Thick target yields were deduced from the fitted experimental cross sections.

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