The Data

The central database used is named the SDC International Mergers Acquisitions Database . This database records all large M As since the late seventies for US companies, while all major international transactions are recorded as of 1985. The last recorded transactions are dated at the begiiming of 1998. Since the SDC database originates in the US, it is probably biased towards recording transactions involving US entities, and possibly European ones. This caveat must be borne in mind when absolute comparisons are made. However, this should not affect relative comparisons, that is when shares and growth rates are computed. 

We have extracted transactions where the primary SIC code of either the acquirer or the target firm belongs to one of the following industries chemicals and allied products (SIC 28), petroleum refining (SIC 29), rubber and plastic (SIC 30) or oil and gas extraction (SIC 13). 

The information provided for each transaction is both qualitative and quantitative. It includes variables such as the date of transaction, the 4-digit affiliation of the companies involved, name and nationality of the target firm, of the acquirer and of the ultimate parent company, the percentage shares acquired, and the form of the transaction. In addition, there are some financial data about the target firm such as sales, intangible assets, and R D expenditures. 

The information we retrieved are the date of the transaction, the name and nationality of the target firm and of the ultimate parent, the SIC codes of the firms involved, the percentage of shares acquired, and R D expenditures. Flows of investment are described in terms of number of transactions reported in the database. This is obviously an imperfect measure of FDI, as it does not take into account the cost of the acquisition and the turnover of the target company. Nevertheless, it is possible to describe the changes in relative flows of investments, and how the presence of European and American firms has changed over time in the main regions of the world. 

A transaction will be called intra-regional if the acquirer and target firms belong to the same region (e.g. Western Europe), and international or cross-border if the firms involved originate in two distinct regions. 

In July 1998, the Minnesota Department of Labor and Industry sent out a safety survey to 230 state firms that had applied for a program called the Miimesota Safety Grant Program. The Safety Grant Program 

Preference imder the Safety Grant Program was given to firms with a significant employment presence in their geographical area, and to firms where jobs were at risk because of safety shortcomings. This tended to favor small and medium-sized firms established in less urban areas of the state. 

Some 121 firms completed the survey forms, for a sample response rate of 53 percent. The survey consists of 11 sections, covering the general safety record of the company, company and employee characteristics, management culture, human resource practices, safety practices, and safety consultation programs provided by the Minnesota Occupational Safety and Health Administration (MNOSHA) consultation unit. Table 2.1 summarizes the question items included in the 22-page survey. These 121 firms have matched with about 5,125 workers compensation indemnity claims for the years 1990 through 1998— that is, the claims were filed by workers of those 121 firms. Federal employer identification numbers were only available for about 10 percent of fire sample and have proven to be unreliable for matching. Hence, we used the name of 

Safety records and other general information of the respondent firm 

Information on employee characteristics and general employer characteristics 

Thermochemical data on ahphatic hydroxylamines is sparse. Indeed, it is almost totally limited to methylated species and so we include both N- and O-methyl substituted species 

Compound Eormula AHf(s) Reference AHfdq) Reference AAf(g) Reference 

The formal gas phase transmethylation reaction, the sole transalkylation reaction available to us (equation 1), is thermoneutral to within 5 kJmol . 

While there are numerous alcohols and ethers for which enthalpies of formation are known, the bleak thermochemical situation for hydroperoxides (and hydrazines ) parallels that of the hydroxylamines. An obvious comparison is between the heteroatom bonds in peroxide, hydrazine and hydroxylamine as shown in equation 2. 

There are thermochemical data for only one nonmethyl aliphatic hydroxylamine, N,N-diethylhydroxylamine . The enthalpy of formation difference between it and A-methyl-hydroxylamine is 71.6 kJ mol . This is very nearly the same as the difference of 79.7 kJ mol between the corresponding primary and secondary alcohols, ethanol and 3-pen-tanol, where the N of the hydroxylamine is replaced by a CH. Thus, the formal reaction enthalpy of equation 3 is only 8.1 kJmol . 

The correlation between the trend of the fatality data and each of the economic datasets is less visible, and the graphical analysis that is presented below is irrtended to identify these correlations. However the trends of the two economic datasets seem to evolve in oppositioa 

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The data base contains provisions for a simple augmentation by up to eight additional compounds or substitution of other compounds for those included. Binary interaction parameters necessary for calculation of fugacities in liquid mixtures are presently available for 180 pairs. 

Since the accuracy of experimental data is frequently not high, and since experimental data are hardly ever plentiful, it is important to reduce the available data with care using a suitable statistical method and using a model for the excess Gibbs energy which contains only a minimum of binary parameters. Rarely are experimental data of sufficient quality and quantity to justify more than three binary parameters and, all too often, the data justify no more than two such parameters. When data sources (5) or (6) or (7) are used alone, it is not possible to use a three- (or more)-parameter model without making additional arbitrary assumptions. For typical engineering calculations, therefore, it is desirable to use a two-parameter model such as UNIQUAC. 

The most reliable estimates of the parameters are obtained from multiple measurements, usually a series of vapor-liquid equilibrium data (T, P, x and y). Because the number of data points exceeds the number of parameters to be estimated, the equilibrium equations are not exactly satisfied for all experimental measurements. Exact agreement between the model and experiment is not achieved due to random and systematic errors in the data and due to inadequacies of the model. The optimum parameters should, therefore, be found by satisfaction of some selected statistical criterion, as discussed in Chapter 6. However, regardless of statistical sophistication, there is no substitute for reliable experimental data. 

Figure 1 compares data reduction using the modified UNIQUAC equation with that using the original UNIQUAC equation. The data are those of Boublikova and Lu (1969) for ethanol and n-octane. The dashed line indicates results obtained with the original equation (q = q for ethanol) and the continuous line shows results obtained with the modified equation. The original equation predicts a liquid-liquid miscibility gap, contrary to experiment. The modified UNIQUAC equation, however, represents the alcohol/n-octane system with good accuracy. 

To illustrate calculations for a binary system containing a supercritical, condensable component. Figure 12 shows isobaric equilibria for ethane-n-heptane. Using the virial equation for vapor-phase fugacity coefficients, and the UNIQUAC equation for liquid-phase activity coefficients, calculated results give an excellent representation of the data of Kay (1938). In this case,the total pressure is not large and therefore, the mixture is at all times remote from critical conditions. For this binary system, the particular method of calculation used here would not be successful at appreciably higher pressures. 

Type C requires the most complex data analysis. To illustrate, we have reduced the data of Henty (1964) for the system furfural-benzene-cyclohexane-2,2,4-trimethylpentane. VLB data were used in conjunction with one ternary tie line for each ternary to determine optimum binary parameters for each of the two type-I ternaries cyclohexane-furfural-benzene and 2,2,4-... 

Experimental values were interpolated from the data of Brown et al. (1964). ... 

If values for the binary parameters b., in Equation (20) are available, they can be added to the data base and used in ENTH, which now includes this parameter, however, set to zero. 

Two generally accepted models for the vapor phase were discussed in Chapter 3 and one particular model for the liquid phase (UNIQUAC) was discussed in Chapter 4. Unfortunately, these, and all other presently available models, are only approximate when used to calculate equilibrium properties of dense fluid mixtures. Therefore, any such model must contain a number of adjustable parameters, which can only be obtained from experimental measurements. The predictions of the model may be sensitive to the values selected for model parameters, and the data available may contain significant measurement errors. Thus, it is of major importance that serious consideration be given to the proper treatment of experimental measurements for mixtures to obtain the most appropriate values for parameters in models such as UNIQUAC. 

While many methods for parameter estimation have been proposed, experience has shown some to be more effective than others. Since most phenomenological models are nonlinear in their adjustable parameters, the best estimates of these parameters can be obtained from a formalized method which properly treats the statistical behavior of the errors associated with all experimental observations. For reliable process-design calculations, we require not only estimates of the parameters but also a measure of the errors in the parameters and an indication of the accuracy of the data. 

The primary purpose for expressing experimental data through model equations is to obtain a representation that can be used confidently for systematic interpolations and extrapolations, especially to multicomponent systems. The confidence placed in the calculations depends on the confidence placed in the data and in the model. Therefore, the method of parameter estimation should also provide measures of reliability for the calculated results. This reliability depends on the uncertainties in the parameters, which, with the statistical method of data reduction used here, are estimated from the parameter variance-covariance matrix. This matrix is obtained as a last step in the iterative calculation of the parameters. 

Large confidence regions are obtained for the parameters because of the random error in the data. For a "correct" model, the regions become vanishingly small as the random error becomes very small or as the number of experimental measurements becomes very large. 

A high degree of correlation may be beneficial. When the parameters are strongly related, some linear combination of the two parameters may represent the data as well as do the individual parameters. In that case a method similar to that of Bruin and Praus-... 

At low pressures, it is often permissible to neglect nonidealities of the vapor phase. If these nonidealities are not negligible, they can have the effect of introducing a nonrandom trend into the plotted residuals similar to that introduced by systematic error. Experience here has shown that application of vapor-phase corrections for nonidealities gives a better representation of the data by the model, oven when these corrections... 

In many process-design calculations it is not necessary to fit the data to within the experimental uncertainty. Here, economics dictates that a minimum number of adjustable parameters be fitted to scarce data with the best accuracy possible. This compromise between "goodness of fit" and number of parameters requires some method of discriminating between models. One way is to compare the uncertainties in the calculated parameters. An alternative method consists of examination of the residuals for trends and excessive errors when plotted versus other system variables (Draper and Smith, 1966). A more useful quantity for comparison is obtained from the sum of the weighted squared residuals given by Equation (1). 

This sum, when divided by the number of data points minus the number of degrees of freedom, approximates the overall variance of errors. It is a measure of the overall fit of the equation to the data. Thus, two different models with the same number of adjustable parameters yield different values for this variance when fit to the same data with the same estimated standard errors in the measured variables. Similarly, the same model, fit to different sets of data, yields different values for the overall variance. The differences in these variances are the basis for many standard statistical tests for model and data comparison. Such statistical tests are discussed in detail by Crow et al. (1960) and Brownlee (1965). 

The data, both real and generated, were then fit to a function of the form... 

Large errors in the low-pressure points often have little effect on phase-equilibrium calculations e.g., when the pressure is a few millitorr, it usually does not matter if we are off by 100 or even 1000%. By contrast, the high-pressure end should be reliable large errors should be avoided when the data are extrapolated beyond the critical temperature. 

Judgment had to be exercised in data selection. For each fluid, all available data were first fit simultaneously and second, in groups of authors. Data that were obviously very old, data that were obviously in error, and data that were inconsistent with the rest of the data, were removed. 

Detailed discussion of all input options are given in the Data Input section. 

Subroutine VLDTA2. VLDTA2 loads the binary vapor-liquid equilibrium data to be correlated. If the data are in units other than those used internally, the correct conversions are made here. This subroutine also reads the estimated standard deviations for the measured variables and the initial parameter estimates. All input data are printed for verification. 

If the data are correlated assuming an ideal vapor, the reference fugacity is just the vapor pressure, P , the Poynting correction is neglected, and fugacity coefficient is assumed to be unity. Equation (2) then becomes... 

Example 5.2 Table 5.3 gives the data for a ternary separation of benzene,... 

Example 5.4 The data for an aromatics separation are shown in Table 5.5. Assuming the ratio of actual to minimum reflux to be 1.1, determine the best sequence using Eq. (5.8). 

This basic approach can be developed into a formal algorithm known as the problem table algorithm. To jllustrate the algorithm, it can be developed using the data from Fig. 6.2 given in Table 6.2 for AT ,i = 10°C. 

TABLE 6.3 Shifted Temperatures for the Data from Table 6.2... 

The data from Table 7.4 are presented graphically in Fig. 7.11. The optimal is at 10°C, confirming the initial value used for this problem in Chap. 6. 

The reactor is highly exothermic, and the data have been extracted as the molten salt being a hot stream. The basis of this is that it is assumed that the molten salt circuit is an essential feature of the reactor design. Thereafter, there is freedom within reason to choose how the molten salt is cooled. 

Figure 16.1 The grid diagram for the data from Table 6.2.

A number of sources of such data are available in the open literature. Unfortunately, the data to be used are often old, sometimes from a variety of sources, with different ages. Such data can be brought up to date and put on a common basis using cost indexes ... 

Figure E.2. Stream population for targeting the munber of shells for the data from Table 7.1.

Hammen equation A correlation between the structure and reactivity in the side chain derivatives of aromatic compounds. Its derivation follows from many comparisons between rate constants for various reactions and the equilibrium constants for other reactions, or other functions of molecules which can be measured (e g. the i.r. carbonyl group stretching frequency). For example the dissociation constants of a series of para substituted (O2N —, MeO —, Cl —, etc.) benzoic acids correlate with the rate constant k for the alkaline hydrolysis of para substituted benzyl chlorides. If log Kq is plotted against log k, the data fall on a straight line. Similar results are obtained for meta substituted derivatives but not for orthosubstituted derivatives. 

In Appendix 1, the reader will find the data required to calculate the properties of the most common hydrocarbons as well as those components that most frequently accompany them in refinery process streams. The data are grouped in seven categories ( ... 

Generate the data from the method of contributing groups which requires knowledge of the chemical structure and some careful attention. 

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