Computers, electronic

Witn the advent of electronic computers, it is no longer necessary to make drastic simplifying assumptions to reduce the... 

The Supplement B (reference) contains a description of the process to render an automatic construction of mathematical models with the application of electronic computer. The research work of the Institute of the applied mathematics of The Academy of Sciences ( Ukraine) was assumed as a basis for the Supplement. The prepared mathematical model provides the possibility to spare strength and to save money, usually spent for the development of the mathematical models of each separate enterprise. The model provides the possibility to execute the works standard forms and records for the non-destructive inspection in complete correspondence with the requirements of the Standard. 

On the ordinate, two quantities are plotted (i) the mean-field potential between the second electron and the other 1 s electron computed, via the self-consistent field (SCF) process (described later), as the interaction of... 

Reactive aluminas have enabled 85, 90, and 95% -AI2O2 ceramics to be upgraded (16,17), because they could be sintered without fluxes in the temperature range of about 1723—2023 K, rather than 2073—2123 K. Advances in microminiaturization of components for the electronic, computer, and aerospace industries have been directly related to the development of low soda and reactive aluminas (18). 

EGR can seriously degrade engine performance, especially at idle, under load at low speed, and during cold start. Control of the amount of EGR during these phases can be accompHshed by the same electronic computer controller used in the closed loop oxygen sensor TWC system. Thus the desired NO reduction is achieved while at the same time retaining good driveabiUty. 

NFPA 75 Standard for the Protection of Electronic Computer/Data Processing Equipment. National Fire Protection Association, Quincy, MA. 

Industrial process furnaces and ovens Mechanical powertransmission equipment, n.e.c. General industrial machinery and equipment, n.e.c. Electronic computers Computer storage devices Computer terminals Computer peripheral equipment, n.e.c. Calculating and accounting machines, except electronic computers Office machines, n.e.c. ... 

A method is outlined by which it is possible to calculate exactly the behavior of several hundred interacting classical particles. The study of this many-body problem is carried out by an electronic computer which solves numerically the simultaneous equations of motion. The limitations of this numerical scheme are enumerated and the important steps in making the program efficient on the computer are indicated. The applicability of this method to the solution of many problems in both equilibrium and nonequilibrium statistical mechanics is discussed. 

For many years, gear shifting in the automatic transmission has been controlled hydraulically, typically in response to vehicle speed and the position of the engine inlet throttle. In recent times that control has been reassigned to an electronic computer, which facilitates gi eater smoothness and flexibility in shift control. 

American physicist John Vincent Atanasoff collaborates with Clifford E. Berry to design the first digital electronic computer. 

Electronic computer programs for these design standards... 

To properly handle the changing composition relationships it is almost essential to utilize some electronic computer techniques if good accuracy is to be achieved. Even three component systems become tedious using desk size electronic calculators without significant internal memory. Computers can be well programmed to handle the complexities of trial and check for convergence to a preset acceptable limit. 

Eabregas, J. A, Electronic Computer Rates Heat Exchangers, Alco Products Review, Alco Products, Inc., 30 Church St., New York, N.Y, Pall 1956... 

The invention of the germanium transistor in 1947 [I, 2] marked the birth of modem microelectronics, a revolution that has profoundly influenced our current way of life. This early device was actually a bipolar transistor, a structure that is mainly used nowadays in amplifiers. However, logical circuits, and particularly microprocessors, preferentially use field-effect transistors (FETs), the concept of which was first proposed by Lilicnficld in 1930 [3], but was not used as a practical application until 1960 [4]. In a FET, the current flowing between two electrodes is controlled by the voltage applied to a third electrode. This operating mode recalls that of the vacuum triode, which was the building block of earlier radio and TV sets, and of the first electronic computers. 

The author is greatly indebted to Fil. kand. Klaus Appel for carrying out the numerical work by means of an electronic computer of type Alwac IIX-E. 

Because of the success of the r12 method in the applications, one had almost universally in the literature adopted the idea of the necessity of introducing the interelectronic distances r j explicitly in the total wave function (see, e.g., Coulson 1938). It was there-fore essential for the development that Slater,39 Boys, and some other authors at about 1950 started emphasizing the fact that a wave function of any desired accuracy could be obtained by superposition of configurations, i.e., by summing a series of Slater determinants (Eq. 11.38) built up from a complete basic one-electron set. Numerical applications on atoms and molecules were started by means of the new modern electronic computers, and the results have been very encouraging. It is true that a wave function delivered by the machine may be the sum of a very large number of determinants, but the result may afterwards be mathematically simplified and physically interpreted by means of natural orbitals.22,17... 

In mathematics there is a large number of complete sets of one-particle functions given, and many of those may be convenient for physical applications. With the development of the modern electronic computers, there has been a trend to use such sets as render particularly simple matrix elements HKL of the energy, and the accuracy desired has then been obtained by choosing the truncated set larger and larger. Here we would like to mention the use of Gaussian wave functions (Boys 1950, Meckler 1953) and the use of the exponential radial set (Boys 1955), i.e., respectively... 

For atoms, it has been possible during the last few years to program the calculations in the ordinary HF scheme for some electronic computers, and, as soon as one has obtained enough experience in this connection, there will probably be no difficulties in doing the same also for the extended HF scheme sketched in this section. For molecules and crystals, on the other hand, one has probably to be satisfied with comparatively rough approximations for a long time. 

Table X gives an idea of the strength of the various expansion methods, and it shows that, by using the principal term only, one can hardly expect to reach even the above-mentioned chemical margin, even if the wave function W gO(D) is actually very close in the helium case. This means that one has to rely on expansions in complete sets, and the construction of the modern electronic computers has fortunately greatly facilitated the numerical solution of secular equations of high order and the calculation of the matrix elements involved. For atoms, the development will probably go very fast, but, for small molecules one has first to program the conventional Hartree-Fock scheme in a fully self-consistent way for the computers, before the next step can be taken. For large molecules and crystals, the entire situation is much more complicated, and it will hence probably take a rather long time before one can hope to get a detailed understanding of the correlation phenomena in these systems.

When the three coefficients oc12, oc13, and a23 are known, the coexistence curve can be found by simultaneous solution of Eqs. (119) and (120). A numerical iterative technique given by Hennico and Vermeulen (HI) was used by Balder for performing these calculations with a digital electronic computer. 

Electronic computers programmed with sophisticated statistical routines (e.g. variance spectral analysis) facilitate the search for climatic rhythms. The motivation behind this effort is obvious Isolation of real periodicities in climate would be a powerful tool in climate forecasting. However, climatologists have identified only a few statistically significant cycles that are useful for climate forecasting over decades. 

FIGURE 8.1 The Electronic Numerical Integrator and Calculator (ENIAC) and its inventor, J. Presper Eekert, circa 1946. ENIAC was the world s first electronic computer. Courtesy, UNISYS Corporation. 

Quantum mechanics was the dominant theory in chemistry even before the advent of electronic computers. The conventional date for the beginning of this period may be fixed at 1927 with the publications of the Heitler and London paper on hydrogen molecule [3]. The growth of theoretical chemistry (or better, theoretical quantum chemistry) between 1930 and 1960 (thirty years, again, as for the last period) has followed a research programme different from that accepted in the most recent period. 

The definitions given by Coulson to quantum ehemists belonging to this group (electronic computers, or ab initio-ists) is surely outdated. Every quantum chemists is now an "electronic computer" and the differenee between ab-initioists and non ab-initioists is rather... 

M High-performance capacitors are indispensable in electronics (computers, televisions, cars,...). About 20 billion are produced each year. 

Ordejon, P., D. A. Drabold, M. P. Grumback, and R. M. Martin. 1993. Unconstrained Minimization Approach for Electronic Computations Which Scales Linearly with System Size. Phys. Rev. B 14646. 

Recent advances in instrumentation range from novel (laser) sources and highly compact spectrometers over waveguide technology to sensitive detectors and detector arrays. This, in combination with the progress in electronics, computer technology and chemometrics, makes it possible to realise compact, robust vibrational spectroscopic sensor devices that are capable of reliable real-world operation. A point that also has to be taken into account, at least when aiming at commercialisation, is the price. Vibrational spectroscopic systems are usually more expensive than most other transducers. Hence, it depends very much on the application whether it makes sense to implement IR or Raman sensors or if less powerful but cheaper alternatives could be used. 

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