Computer history

The transformation is global. The schemes P and P are strongly computationally equivalent in the restricted sense - if we omit from the test added computational histories of (P,I, a) and (P, I, a) all values of the new variables and all tests involving these variables (i.e. test Z ) for an interpretation I extending I to all of P and P, then the resulting lists are equal. However the loop structure of P has been drastically changed and there is no simple relationship between the graphs of P and P. ... 

Rojas, P. Encyclopedia of Computers and Computer History, Fitzroy Dearborn Chicago, 2001 (2 volumes). 

Vapor degreasers are like automobiles, spaghetti sauce, laptop computers, history textbooks, and television "situation comedies." Within a category, they are all the same and yet they can he consOucted, formulated, designed, written, and programmed completely differently — thus producing different outcomes. 

Rojas, R. and U. Hashagen. 2000. The First Computers—History and Architectures. Cambridge, MA MIT Press. 

Rojas, R., ed. 2001. Encyclopedia of Computer and Computer History. (2 vols.) Chicago Fitzroy Dearborn. This encyclopedia aims to cover the complete subject of computers and their history from personal computing to main-frames to robotics and artificial intelligence as well the theoretical foundations of computer science. The 600+ entries cover facts, definitions, biographies, histories, and explanations of diverse topics. Contributors are scholars in computer science and computer history from around the world. This source will only serve as a starting point for more sophisticated users. 

The reservoir model will usually be a computer based simulation model, such as the 3D model described in Section 8. As production continues, the monitoring programme generates a data base containing information on the performance of the field. The reservoir model is used to check whether the initial assumptions and description of the reservoir were correct. Where inconsistencies between the predicted and observed behaviour occur, the model is reviewed and adjusted until a new match (a so-called history match ) is achieved. The updated model is then used to predict future performance of the field, and as such is a very useful tool for generating production forecasts. In addition, the model is used to predict the outcome of alternative future development plans. The criterion used for selection is typically profitability (or any other stated objective of the operating company). 

J. Lederberg, How DENDRAL was conceived and bom, in ACM Symposium on the History of Medical Informatics, National Library of Medidne, 1987. Later published in A History of Medical Informatics, B. I. Blum, K. Duncan (Eds.), Association for Computing, Machinery Press, New York 1990, 14-44. 

This characteristic is commonly referred to as the bracketing theorem (E. A. Hylleraas and B. Undheim, Z. Phys. 759 (1930) J. K. E. MacDonald, Phys. Rev. 43, 830 (1933)). These are strong attributes of the variational methods, as is the long and rich history of developments of analytical and computational tools for efficiently implementing such methods (see the discussions of the CI and MCSCF methods in MTC and ACP). 

The DIIS method is not without cost. A history of Fock matrices must be maintained and appropriate memory allocated. In addition, the computational cost of generating anew Fock matrix is significant. Also, in very rare cases, the solution found by this method is very different from that found in other ways. 

Monte Carlo (MC) techniques for molecular simulations have a long and rich history, and have been used to a great extent in studying the chemical physics of polymers. The majority of molecular modeling studies today do not involve the use of MC methods however, the sampling capabiUty provided by MC methods has gained some popularity among computational chemists as a result of various studies (95—97). Relevant concepts of MC are summarized herein. 

As we have repeatedly seen in this chapter, proponents of computer simulation in materials science had a good deal of scepticism to overcome, from physicists in particular, in the early days. A striking example of sustained scepticism overcome, at length, by a resolute champion is to be found in the history of CALPHAD, an acronym denoting CALculation of PHAse Diagrams. The decisive champion was an American metallurgist, Larry Kaufman. 

The Seismic Safety Margins Research Program developed a computer code called SMACS (Seismic Methodology Analysis Chain with Statistics) for calculating the seismic responses of structures, systems, and components. This code links the seismic input as ensembles of acceleration time histories with the calculations of the soil-structure interactions, the responses of major structures, and the responses of subsystems. Since uses a multi-support approach to perform the time-history response calculations for piping subsystems, the correlations between component responses can be handled explicitly. SMACS is an example of the codes that are available for calculating seismic response for PSA purposes. 

Typical pressure and temperature histories computed are shown in Figs. 6.6 and 6.7. In Figs. 6.6, the pressure is shown as a function of position within the powder compact at various times. For the baratol explosive loading shown, an initial wave, whose pressure is 1.8 GPa, is shown moving slowly from right to left. Upon reflection from the rear interface with the copper, the pressure jumps to a much higher value and then quickly reverberates to a peak pressure of about 11.4 GPa. The shorter reverberation time reflects the higher wavespeed and the major reduction in thickness in the compressed powder. 

---