Computer program checking

The best approach is to have a computer program check a series of pressure drops and see how energy requirements decrease as surface increases. If this Option is not available, the following simple method can be used to obtain specification sheet values. Start with a pressure drop of 6.9 kPa (1 psi), and anolv three correction factors, F and F, as follows. 

For each gas, skeleton tables of the properties are given at several temperatures so that computer program checks can be made. 

Near top speed, a fan may operate at a speed that is near or above the natural frequency of the wheel and shaft. Under such conditions, the fan can vibrate badly even when the wheel is clean and properly balanced. Whereas manufacturers often do not check the natural frequency of the wheel and shaft ia standard designs, many have suitable computer programs for such calculations. Frequency calculations should be made on large high speed fans. The first critical wheel and shaft speed of a fan that is subject to wheel deposits or out-of-balance wear should be about 25—50% above the normal operating speed. 

The relative merits of various MO methods have been discussed in die literature. In general, the ab initio type of calculations will be more reliable, but the semiempirical calculations are faster in terms of computer time. The complexity of calculation also increases rapidly as the number of atoms in the molecule increases. The choice of a method is normally made on the basis of evidence that the method is adequate for the problem at hand and the availability of appropriate computer programs and equipment. Results should be subjected to critical evaluation by comparison widi experimental data or checked by representative calculations using higher-level mediods. Table 1.12 lists some reported deviations from experimental AHf for some small hydrocarbons. The extent of deviation gives an indication of the accuracy of the various types of MO calculations in this application. 

The entries of this index were derived directly by computer program from the lists of references. The accuracy of the references was the sole responsibility of the authors. No editorial check, except for format and journal-title abbreviation, was applied. Consequently, errors occurring in authors names in the references will recur in this index. 

Analysis of the chromatogram is carried out Interactively with the operator directing the flow of analysis from the computer keyboard, or in the automatic mode immediately after data collection to an extent specified using SETUP. Automatic analysis may also be applied to a series of chromatograms at any time by putting the run numbers or names of the files in the run number file. Before the next set of data collections, the programs check that the number in the run number file is the latest run number for all the files on the disk. 

A general approach was developed by G.E.P. Box and G.M. Jenkins (S) which combines these various methods into an analysis which permits choice of the most appropriate model, checks the forecast precision, and allows for interpretation. The Box-Jenkins analysis is an autoregressive integrated moving average model (ARIMA). This approach, as implemented in the MINITAB computer program is one used for the analyses reported here. 

To check this prediction, a number of MaxEnt charge density calculations have been performed with the computer program BUSTER [42] on a set of synthetic structure factors, obtained from a reference model density for a crystal of L-alanine at 23 K. The set of 1500 synthetic structure factors, complete up to a resolution of 0.555 A [45], was calculated from a multipolar expansion of the density, with the computer program VALRAY[ 46],... 

To make the phase angle plot, we simply use the definition of ZGp(joo). As for the polar (Nyquist) plot, we do a frequency parametric calculation of Gp(jco) and ZGp(joo), or we can simply plot the real part versus the imaginary part of Gptjco).1 To check that a computer program is working properly, we only need to use the high and low frequency asymptotes—the same if we had to do the sketch by hand as in the old days. In the limit of low frequencies,... 

The documentation also gives the input and output formats. On a complex computer program the user will rarely be completely satisfied with these. Often the user would like to be able to transmit the output directly to management or operators so they can make certain decisions. There will be some format that is best for insuring that these results can be interpreted quickly and easily. This best format undoubtedly will change as new procedures are adopted. The evaluator should check to see that both the input and output formats are flexible or can be made flexible. The evaluator should also determine whether the data bank can be easily updated. 

Don t rely on computer spell check programs to find all of your mistakes. Follow the professional proofreading tricks to be certain your essay has no spelling errors. 

While there have been improvements in computer grammar checking, nothing is more effective than a careful review of your writing after using the program. 

Researchers can use computer programs to test the geometry of many molecular structures and determine their suitability for specific applications. For example, a specialized screen saver can check the shape of hypothetical molecules based on their suitability for cancer treatment. Anyone can upload the screen saver and use a computer s idle time... 

Exercise 1. From the values of Table 1 and Eq.(lO), write a computer program using a fourth order Runge-Kutta or fifth order Runge-Kutta-Fehlberg method and reproduce Figures 2, 3, 4, 5. In order to check that the chaotic behavior has been reached, it is necessary to run the program with two initial conditions very close, for example ... 

Exercise 6. Show that the equilibrium point of the model defined by Eq.(34) and the simplified model R given by Eq.(35), i.e. when the dynamics of the jacket is considered negligible, are the same. Deduce the Jacobian of the system (35) at the corresponding equilibrium point. Write a computer program to determine the eigenvalues of the linearized model R at the equilibrium point as a function of the dimensionless inlet flow 4 50. Values of the dimensionless parameters of the PI controller can be fixed at Ktd = 1-52 T2d = 5. The set point dimensionless temperature and the inlet coolant flow rate temperature are Xg = 0.0398, X40 = 0.0351 respectively. An appropriate value of dimensionless reference concentration is C g = 0.245. Does it exist some value of 2 50 for which the eigenvalues of the linearized system R at the equilibrium point are complex with zero real part Note that it is necessary to vary 2 50 from small to great values. Check the possibility to obtain similar results for the R model. 

The back pressure on the safety, valve due to the flow through the discharge line can be calculated using a suitable computer program (see Annex 4). However, the Omega method (see Annex 8). ban also be used to check that the back pressure is not excessive, if it is applicable and if the discharge piping from a safety valve is of constant diameter. 

Element standards were grouped into four standard libraries, corresponding to the four decay counting times. Decay time boundaries for each standard library are shown in Table II. In each library, at least two elements were calculated from different standards. These two standards represented different concentrations, counting geometries, dead times, decay times, and sample matrices. Visual inspection of the computer listing provided a rapid spot check for computer program malfunctions. 

Write a computer program to multiply two rectangular matrices of maximum size 20 by 20. Check it out on some simple examples. 

Typical plots of AE vs. a dimensionless function of tV2 in Fig. 7 are reproduced from a discussion of the potentialities of the galvanostatic step method given by Kooijman and Sluyters [32], It is seen that, at sufficiently large times, AE becomes a linear function of t1/2. At first [31], analysis procedures of the complex AE vs. tvl relation were based on extrapolation of this linear section to tyl = 0, yielding the intercepts indicated in Fig. 7. However, it has been shown that, in this way, the content of information about the kinetic parameters, k and a, is not optimally utilized [32], Therefore, numerical analysis of the complete AE vs. t response with the aid of suitable computer programs has to be advocated. In principle, such an analysis yields the values of X, R , and Cd as well as a check on the validity of eqn. (30). 

The answer addresses one of the key modern engineering dilemmas, that of providing engineering judgment to evaluate calculations from black-box complex computer codes. Computer programs may provide a number that may not be a good model of physical reality. The simpler methods in this chapter are very valuable, first for intuitive understanding and second to provide both a first estimation and a check of more complex calculations. 

Campbell s series [5] states that many authors recommend, as do I, the O Connell method for hydrocarbons. You may select the two-film method by entering T. The Fractionation Research Institute (FRI) has for more than 30 years used and proven a much more thorough method called the two-film method, which is equally applicable to both fractionators and absorbers [6], The FRI method accounts for the actual tray internal configuration and fluid dynamics, making it far superior to the O Connell method. I have therefore produced a type of two-film method for determining tray efficiency that has been checked to be within 3% accuracy of hundreds of answers calculated with the FRI method. Called the Erwin two-film method, it is recommended for all types of trays and will also calculate the liquid tray residence time in seconds. This method is included in the three tray computer program executable files in the CD accompanying this book. 

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