STRETCH computer

Mader (Addnl Ref N) determined C-J parameters for many C-H-N-0 expls using for calculations the IBM-7030 STRETCH Computer, and the Code STRETCH BKW which was described in Los Alamos Scientific Laboratory Report "STRETCH BKW - A Code for Computing the Detonation Properties of Explosives ... 

IBM-7030 STRETCH Computer using the Becker-Kistiakowsky-Wilson equation of state. These parameters are listed by us under "Detonation (and Explosion), Equations of State Used in . He also detd several Chapman-Jouguet parameters... 

The selection rules for the QM harmonic oscillator pennit transitions only for An = 1 (see Section 14.5). As Eq. (9.47) indicates diat the energy separation between any two adjacent levels is always hm, the predicted frequency for die = 0 to n = 1 absorption (or indeed any allowed absorption) is simply v = o). So, in order to predict die stretching frequency within the harmonic oscillator equation, all diat is needed is the second derivative of the energy with respect to bond stretching computed at die equilibrium geometry, i.e., k. The importance of k has led to considerable effort to derive analytical expressions for second derivatives, and they are now available for HF, MP2, DFT, QCISD, CCSD, MCSCF and select other levels of theory, although they can be quite expensive at some of the more highly correlated levels of theoiy. 

FIGURE 8.15 Quick stretches computed from the distributed muscle fiber model. (Adapted from Palladino, J.L. and Noordergraaf, A. 1998. Springer-Verlag, New York, pp. 33-57.)... 

Figure 8.15 shows quick stretches computed for the distributed fiber model. Stretches corresponding to 0.2% of sarcomere length were performed over 10 msec. Curves show rapid force overshoot, followed by rapid recovery and slow recovery back to the isometric force levels. Quick stretch response is in agreement with classic studies on muscle strip and recent studies on ferret papillary muscles [39]. 

R. ALPAIR, "Methuselah L A Universal Assessment Programme for Liquid Moderated Reactor CeUs, Using IBM 7090 or Stretch Computers," AEEW-R 13S, United Kiiigdom Atomic Energy Authority (1964). 

Byte In most computers, the unit of memory addressing and the smallest quantity directly manipulated by instructions. The term byte is of doubtfiil origin, but was used in some early computers to denote any field within a word (e.g., DEC PDF-10). Since its use on the IBM Stretch computer (IBM 7030) and especially the IBM System/360 in the early 1960s, a byte is now generally understood to be 8 bits, although 7 bits is also a possibility. 

ALPIAR R. METHUSELAH I - A universal assessment programme for liquid moderated reactor cells using IHl 7090 or STRETCH computers. AEEW - R 135, 1964. 

The real power of using stretching computations to characterize chaotic flows lies in the fact that stretching is the link between the macro- and micromixing intensities in laminar mixing flows. In this section we describe the method for computing striation thickness distribution in our 3D example, the Kenics mixer. 

We used the direct relationship between intermaterial area density (p) and stretching (k) stated in eq. (3-15) to compute the spatial structure of p in the Kenics flow. Approximately 4 x 10 tracer particles were used in the stretching computations to assure statistically significant results. The specific method is as follows First, the accumulated stretching of all the tracer filaments was recorded after 2, 6, 10, and 22 Kenics mixer elements. Then a uniform lattice of 225 x 225... 

For each pair of interacting atoms (/r is their reduced mass), three parameters are needed D, (depth of the potential energy minimum, k (force constant of the par-tictilar bond), and l(, (reference bond length). The Morse ftinction will correctly allow the bond to dissociate, but has the disadvantage that it is computationally very expensive. Moreover, force fields arc normally not parameterized to handle bond dissociation. To circumvent these disadvantages, the Morse function is replaced by a simple harmonic potential, which describes bond stretching by Hooke s law (Eq. (20)). 

A restrain t (not to be confused with a Model Builder constraint) is a nser-specified one-atom tether, two-atom stretch, three-atom bend, or four-atom torsional interaction to add to the list ol molec-11 lar mechanics m teraction s computed for a molecule. These added iiueraciious are treated no differently IVoin any other stretch, bend, or torsion, except that they employ a quadratic functional form. They replace no in teraction, on ly add to the computed in teraction s. 

There are forces other than bond stretching forces acting within a typical polyatomic molecule. They include bending forces and interatomic repulsions. Each force adds a dimension to the space. Although the concept of a surface in a many-dimensional space is rather abstract, its application is simple. Each dimension has a potential energy equation that can be solved easily and rapidly by computer. The sum of potential energies from all sources within the molecule is the potential energy of the molecule relative to some arbitrary reference point. A... 

Polymers will be elastic at temperatures that are above the glass-transition temperature and below the liquiflcation temperature. Elasticity is generally improved by the light cross linking of chains. This increases the liquiflcation temperature. It also keeps the material from being permanently deformed when stretched, which is due to chains sliding past one another. Computational techniques can be used to predict the glass-transition and liquiflcation temperatures as described below. 

Results of a recent literature study indicate that frequencies computed using semi-empirical PM3, AMI, and MNDO methods compare well to values obtained at iht ab initio level using medium size basis sets. Of these three methods, PM3 showed the closest correspondence to experimental values, which is generally about 10 percent too high in value from stretches (Seeger, D.M. Korze-niewski, C. Kowalchyk, W., J. Phys.Chem. 95 68-71, 1991). 

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