Analogue computer

Two open reservoirs with cross-sectional areas Ai, A2 and liquid depths hi and h2 respectively are connected by a pipeline of length L and diameter D. The resulting liquid levels form a decaying oscillatory response to final steady state. Ramirez (1976) provides a detailed model derivation for this problem and shows how the problem is solved by analogue computation. The parameters are the same as those used by Ramirez. 

The use of computers has made it possible to characterise models with large numbers of individual steps. Andersson and Lamb [25] used an analogue computer to estimate parameters in a model with 15 reactions which described naphthalene production by hydrodealkylation. Also, they were able to predict temperature distributions and effluent concentrations for a commercial reactor. Kurtz [26] took 200 simultaneous reactions into account in an experimental study of the gas-phase chlorination of methyl chloride. Model discrimination and parameter estimation for catalytic processes are discussed in a comprehensive review by Froment [27]. 

Panned (P4) and Jurges (J8) laid the basis for such predictions and more recently analogue computers have been applied to this problem (J6, S6). In principle, such predictions involved the solution of the general energy equation which may be written in the following form for two-... 

Methods in Computation and Simulation, McGraw-Hill, NY(1954) 4)C. A.A.Wacs, "Introduction to Electronic Analogue Computers, Pergamon Press, London(l955)... 

The limitations mentioned do not apply if the work can be done on a machine various types of mechanical and electrical analogue machines for Fourier synthesis have been described (see Lipson and Cochran, 1953), culminating in Pepinsky s XRAC (X-ray analogue computer), in which structure amplitudes and phases for a two -dimensional synthesis are put in on an array of dials, and the electron density map appears at once on a cathode ray tube (Pepinsky, 1952). An increasing proportion of Fourier syntheses (and indeed crystallographic calculations of all types) is done on electronic digital computers. 

Such was the state of the art when Amundson and Bilous s paper was published in the first volume of the newly founded A.I.CH.E. Journal (Bilous and Amundson, 1955). This for the first time treated the reactor as a dynamical system and, using Lyapounov s method of linearization, gave a pair of algebraic conditions for local stability. One of these corresponded to the slope condition of previous analyses, and there was a brief flurry of attempts to invest the other with a similarly physical explanation. For the global picture they introduced the phase plane (another feature of the theory of dynamical systems) and, with consummate skill, Bilous conjured the now classic figures from a Reeves electronic analogue computer. Even in this early paper, they had touched upon the consecutive reaction scheme A - B - C and had shown that up to five steady states might be expected under some conditions. 

Fig. 3.2 Analogue computer-generated curves showing the levels (as fraction of the intravenous dose) of benzylpenicillin in the central (serum) and peripheral (tissue) compartments of the two-compartment pharmacokinetic model and the cumulative amount excreted unchanged in the urine as a function of time. The curves are based on the first-order rate constants (k12, k21, kel) associated with the compartmental pharmacokinetic model. Note...

Comparatively simple analogue computers, specifically designed for ilour formulation, have achieved a good measure of success. An example such an instrument is the Colorant Mixture Computer (often abbrevi-ed to COMIC) the panel of which is shown in Fig. 26.36 (Davidson. al., J.S.D.C., 1963, 79, 577). The spectrophotometric reflections of... 

As limited by the maximum number of data points (single scan, sample and background, widest spectral range, single-sided interferogram). Analogue computer. 

Oxygen Supply to Tissue, as Studied by an Analogue Computer, Oxygen Transport in Tissue Workshop, Dortmund, Germany, July 1971. 

However, later experiments have indicated that a considerable fraction of water is removed in phase 2 [91], probably as liquid into the felt. Subsequent analogue computations by Deploy [92] suggest that the felt does indeed hinder evaporation, with the wet web leaving the cylinder at a higher temperature than when the cylinder was unfelted. The net effect is that a felted cylinder has slightly less moisture loss than an unfelted one for the same initial conditions. 

Weaker arguments could have been made for adopting continuous time analogue computers operate in continuous time, and certain physicochemical quantities can be transduced continuously. However, it is important to note that in most applications the real time is transformed to state-time (e.g. number of generations). 

Analogue computer (Vannevar Bush) Bush builds the first analogue computer. He is also the first person to describe the idea of hypertext. 

Analogue computer (George Philbrick) PhUbrick builds the Automatic Gontrol Analyzer, which is an electronic analogue computer. 

An alternative to (iii) is to Laplace transform directly the experimental data (e.g. by using analogue computer elements) and to compare this data with the theoretical expression in the s-space. 

Measurements on deulerated analogue computer simulation used 6H 0.04 and 0.02 mT. 

Unfortunately neither picryl chloride nor bromide gave first order plots for the disappearance of the intermediate. Analogue computer analysis showed that this was not simply due to competition between rates of formation and disappearance. Good agreement between observed and analogue computer simulated rates was obtained if a second intermediate was introduced into the model. The most likely species corresponding to this intermediate is the Meisenheimer complex produced by addition of hydroxide at the 3-position. This model produces the scheme shown below ... 

More recently, information on the sequence distribution has been obtained by NMR techniques (Mochel and Johnson, 1%9) based on the relative shifting of two peaks attributed respectively to the (meta + para) protons and to the ortho protons on the styrene ring, and to the subsequent use of curve analysis techniques using an analogue computer. The results obtained were found to agree well with those predicted from data on monomer reactivity ratios. 

Isenberg, C. (1976) The Soap Film An Analogue Computer, American Scientist, 64, 5, 514. 

Two dynamic problems are of particular Interest in the design of SGHWRs which are not covered by the overall plant analogue computer control studies. These are the questions of hydraulic stability and the behaviour of the coolant flow following pump failure. The SPLOSH code has been developed to study these and related problems. Essentially the code provides a... 

An extremely valuable contribution to control system design has been provided by the digital and analogue system simulations developed over the past years. It is, therefore, worthwhile to outline the basic content of the current wide range simulator which is programmed on a PACE analogue computer. 

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