Log calculation

Molality Experimental Mean Attivity Coefficient, -log Calculated... 

Values of — log/, calculated for various types of electrolytes in concentrations ranging from 0.001 to 0.01 normal, are found in the following table. Normality is defined in the usual way i.e. a 0.005 molar barium chloride solution (bi-univalent) is 0.01 normal. 

This is the log calculated by a group-contribution method proposed by Hou and Xu [Hou and Xu, 2002 Hou and Xu, 2003a Hou and Xu, 2003b] based on the calculation of —> solvent accessible surface area for 100 atom/group types, together with two additional correction factors, and defined as... 

This is the log calculated by a simple approach based on the contributions of molecule atoms and bonds, as [Duchowicz and Castro, 2000]... 

Where activity coefficients are expected to deviate significantly from unity, for example, when divalent or multivalent ions are present in the solution or concentrations of the surfactant exceed 10-2 M, d log C j in the appropriate equation may be replaced by Debye-Hiickel equation,... 

In preparation for a field wide quick look correlation, all well logs need to be corrected for borehole inclination. This is done routinely with software which uses the measured depth below the derrick floor ( alonghole depth below derrick floor AHBDFor measured depth , MD) and the acquired directional surveys to calculate the true vertical depth subsea (TVSS). This is the vertical distance of a point below a common reference level, for instance chart datum (CD) or mean sea level (MSL). Figure 5.41 shows the relationship between the different depth measurements. 

Connecting the measured points will result in a curve describing the area - depth relationship of the top of fhe reservoir. If we know the gross thickness (H) from logs we can establish a second curve representing the area - depth plot for the base of the reservoir. The area between the two lines will equal the volume of rock between the two markers. The area above the OWC is the oil bearing GRV. The other parameters to calculate STOIIP can be taken as averages from our petrophysical evaluation (see Section 5.4.). Note that this method assumes that the reservoir thickness is constant across the whole field. If this is not a reasonable approximation, then the method is not applicable, and an alternative such as the area - thickness method must be used (see below). 

From the probability distributions for each of the variables on the right hand side, the values of K, p, o can be calculated. Assuming that the variables are independent, they can now be combined using the above rules to calculate K, p, o for ultimate recovery. Assuming the distribution for UR is Log-Normal, the value of UR for any confidence level can be calculated. This whole process can be performed on paper, or quickly written on a spreadsheet. The results are often within 10% of those generated by Monte Carlo simulation. 

Josh Barnes and Piet Hut. A hierarchical o(n log n) force-calculation algorithm. Nature (London), 324 446-449, December 1986. 

The HYBOT descriptors were successfully applied to the prediction of the partition coefficient log P (>i--octanol/water) for small organic componnds with one acceptor group from their calculated polarizabilities and the free energy acceptor factor C, as well as properties like solubility log S, the permeability of drugs (Caco-2, human skin), and for the modeling of biological activities. 

To become familiar with the application of the basic principles of the model building process by means of calculating log P and log 5 values... 

These few examples are of course a small and arbitrarily chosen set of methods for the calculation of log P values. Nevertheless, it is hoped that they demonstrate some basic principles in the prediction of a physicochemical property. 

The group contribution method allows the approximate calculation of solubility by summing up fragmental values associated with substmctural units of the compounds (see Section 7.1). In a group contribution model, the aqueous solubility values are computed by Eq. (12), where log S is the logarithm of solubility, C is the number of occurrences of a substmctural group, i, in a molecule, and is the relative contribution of the fragment i. 

Thus, a list of 1 5 descriptors was calculated for these purposes, as described below. The partition coefficient log P (calculated by a method based on the Gho.sc/Crip-pen approach [11]) (see also Chapter X, Section 1.1 in the Handbook) was calculated because it affects the solubility dramatically [17, 18]. All the other descriptors were calculated with the program PETRA (Parameter Estimation for the Treatment of Reactivity Applications) [28. ... 

However, for screening large databases it is still necessary to use the easily calculated log P value. 

The IlyperChein log file includes calculated dipole moments of 111 oiccu les. To set th e am min t o f in form anon collected in th e log file, eh an gc the value of the Qu an turn Prin t Level set tin g in the eh em. in 1 File. Xote that the sign convention used in the quantum mechanical calculation of dipoles is opposite to that used in 111 oiccu lar mech an ics dipole calculation s this reflects th e differing sign conventions ofphysics and chemistry. 

The dipole moment for a calculation is reported and is contained in the log file if logging is turn ed on. It is also reported on the status line if you Display DipoleMoment on iheDisplay menu. Other expectation values besides the dipole moment (for example, qna-dnipole moment ) could he reported with a wave function but the set reported with this release of HyperChem is limited to on ly a few. Below we discuss the properties or oth er ch aracteri/ation s of the calculated wave function that can he interactively visnali/ed. 

For a molecular mechanics calculation the en ergy and the gradient are essen tially the on ly quantities available from a single pom t cal-cii lation. An analysis of the com ponen ts of th is molecular mechanics energy is placed in the log file for further detail. In the case of MM-h a much more com pleie description of the ind ividual... 

Calculating log Pact from Structures. Chemical Reviews 93 1281-1306. 

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