Calculators, desk

This applies to work where at least 50 percent of the time is by electronic desk calculator for the numerical calcula-... 

Direct desk calculations would have indicated the overall energy flows between the inlet and outlet states, but may not have shown the cycles. 

Ideally, this information should be made available in the form of easy-to-use nomographs or empirical equations which can be quickly and rapidly solved on a programmable desk calculator. New instrumentation which can be used on an in-line basis to analyze process streams for the concentrations of plutonium in different oxidation states is also needed. 

For practical calculation on a desk calculator, the following transformation is strongly recommended ... 

Finally, this procedure was devised for a desk calculator and is convenient only in combination with this technique. If a computer is used. 

Brinkley (1947) published the first algorithm to solve numerically for the equilibrium state of a multicomponent system. His method, intended for a desk calculator, was soon applied on digital computers. The method was based on evaluating equations for equilibrium constants, which, of course, are the mathematical expression of the minimum point in Gibbs free energy for a reaction. 

Hazard Screening Desk Calculation Reaction enthalpy, RXN Need formation energy data or derive it Must know precise stoichiometry Known reactions only, no rate information... 

The weight signal is normally recorded in the manner indicated above. The first derivation can be performed with a derivative computer and is recorded simultaneously. Another way today is the use of a small or large programmable desk calculator which is connected to the thermobalance with an interface. The print-out of weight change per time unit gives the same information as the DTG-curve. 

In an effort to understand the formidable-appearing output of many computations for a wide variety of C-H-N-O explosives at various initial loading densities, we have investigated interrelationships between such properties as pressure, velocity, density, heat of reaction, etc. These studies have led to a number of interesting observations, important among which were the facts that much simpler semiempirical formulas could be written for desk calculation of detonation velocities and detonation pressures, with about the same reliance on their answers as one could attach to the more complex computer output. These equations require as input information only the explosive s composition and loading density and an estimate of its heat of formation, and, in their comparative simplicity,... 

Equations (8) and (13) -(15) provide the basis for a simple method of estimating detonation pressures, which requires as input information only the elemental composition, loading density, and an estimate of the heat of formation of the explosive. With the aid of a desk calculator, a typical calculation requires less than... 

This method is preferable to the deviation technique when a desk calculator which can accumulate squares is available. 

In ail applications of multiple regression which involve equations of more than three terms, a digital computer programme is practically a must. In using the analysis of variance, a fairly useful rule of thumb is that up to 100 data points is not too much to handle by the desk calculator route. 

Afterwards there appeared what has become the main application liquid crystal displays (LCDs) based on the twisted nematic (TN) mode. These are commonly used for flat panel displays (e.g., desk calculators). Thin film transistor (TFT) LCDs enabled a large number of segments (e.g., 640 x 1024) to be used and they had advantages like... 

The last part of the book is devoted to the development of simple integrative models of organic chemicals in real environmental systems. The compound-specific tools derived in Parts II and III will be combined with the modeling tools of Part IV. As before, the aim of the discussion is not to compete with the many rather sophisticated models of environmental systems which can be found in the literature, but to concentrate on the simple models which can be analyzed by hand or with desk calculators. 

Until the advent of computers, multicomponent distillation problems were solved manually by making tray-by-tray calculations of heat and material balances and vapor-liquid equilibria. Even a partially complete solution of such a problem required a week or more of steady work with a mechanical desk calculator. The alternatives were approximate methods such as those mentioned in Sections 13.7 and 13.8 and pseudobinary analysis. Approximate methods still are used to provide feed data to iterative computer procedures or to provide results for exploratory studies. 

Fig. 9.11. Grindo-Sonic equipped with desk calculator (courtesy Lemmcns-Electronica).

The standard statistical formulas summarized below were incorporated in a program used in a desk calculator to find the best line... 

A further advantage of spectrophotometers is the ready availability of a number of low-cost instruments with sufficient accuracy and reproductivity for dyebath analysis. Much of the work in the current study was carried out on a single-beam grating spectrophotometer costing approximately 2,000. The computations necessary in the analysis can be conveniently carried out on low-cost desk calculators or microprocessors. The calculations necessary for a four-dye mixture (or three dyes plus background) can be handled on a system costing less than 1,000. The least-squares fit of 16 points of the absorption spectrum can be carried out on a 3,000 minicomputer. Development of these low-cost instrument-minicomputer systems is largely responsible for consideration of dyebath reuse as a practical reality for the textile industry. 

These are four-parameter equations, and Lola Deming spent weeks at her desk calculating machine to fit the curves that Lambert and Clark obtained for the adsorption of benzene on ferric oxide gel (21). These isotherms are shown in Figure 5. I do not blame anyone for not using these equations, and actually very few have used them to date. Joyner and Emmett (20) were among the hardy souls who did. Clampitt and German published another paper very recently (II), which is well worth reading for all those who deal with Type IV isotherms. 

Although Mie s theory was first published in 1908, computations of scattering coefficients were not tabulated to any extent until the 1940s (Lowan, 1948), and then the available tables were quite limited. Nevertheless, considering that each data point represented many hours of error-free calculation with a desk calculator, the accuracy of these early tables is indeed remarkable. 

Computational chemistry was able to develop thanks to two major advances first was the understanding and formulation of a mathematical description of the microscopic behavior of matter, and second was the technical development of computers much more powerful than mechanical desk calculators. A large part of the foundation of the mathematical theory was laid by the physics community in Europe in the 1920s. The University of Gottingen in Germany became a center of the new quantum mechanics. 

I used these tables of Preul for the first part of my doctoral work. The computation of integrals for a valence bond treatment of the H-F molecule on a mechanical desk calculator was greatly simplified by the fact that I could look up values for the required auxiliary functions in these tables. Toward the end of this work (1962-1963), I got access to the electronic computer Z23, which of course could perform the calculations in a much shorter time with much higher accuracy. 

Table 2.S, together with the subsequent worked examples, illustrates the application of the statistical tests to real laboratory situations. Equation (2.10) is a simplified expression derived on the assumption that the precisions of the two sets of data are not significantly different. Thus the application of the F-lest (equation 2.8)) is a prerequisite for its use. The evaluation of t in more general circumstances is of course possible, but from a much more complex expression requiring tedious calculations. Recent and rapid developments in programmable desk calculators are removing the tedium and making use of the general expression more acceptable. The references at the end of the chapter will serve to amplify this point. ...

These ideas were first suggested by Bliss (1934) and were later extended by Finney (1964). Although the iterative procedure of probit analysis can be performed manually with a desk calculator (Finney, 1964), in recent years the method has been conveniently computerized (Finney, 1971 SAS Institute, 2002-2003). An example of probit analysis using the SAS system is illustrated in Appendix 5.1. 

Our choice of model differs from that of Tschernitz et al. (1946), who preferred Model d over Model h on the basis of a better fit. The difference lies in the weightings used. Tschernitz et al. transformed each model to get a linear least-squares problem (a necessity for their desk calculations) but inappropriately used weights of 1 for the transformed observations and response functions. For comparison, we refitted the data with the same linearized models, but with weights Wu derived for each model and each event according to the variance expression in Eq. (6.8-1) for In 7. The residual sums of squares thus found were comparable to those in Table 6.5. confirming the superiority of Model h among those tested. 

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