Hierarchies

It is useful to retain the hierarchy of a Verilog HDL model in terms of always statements. This enables a hierarchy of sub-circuits to be produced by the synthesis tool that a logic optimizer can effectively handle. 

Quite often, a synthesis tool might automatically preserve the hierarchy of a large datapath operator. For example, 

In this case, a synthesis tool may preserve the 16-bit adder as a separate hierarchy. 

Anyone eating a steak or a slice carved from roast beef knows that meat is fibrous in texture. These fibers, 20 to 100 fj.m in diameter and very long, are the multinucleate muscle cells of which skeletal muscles are composed (Fig. 1 A, B). Such fibers in the light microscope appear cross-striated and the muscles from which they are derived are known as striated muscles. The term striated also covers the muscles in animal hearts (Fig. 1C), but here the cells (the myocytes) are much shorter, they contain a single nucleus, and they are linked end to end by special structures known as 

A closer look at striated muscle fibers shows that they themselves are assemblies of fine, hairlike structures known as myofibrils (Fig. 1A, B). Myofibrils may be about 2 to 5 jxm in diameter, with cell organelles such as mitochondria and membranous systems called T-tubules and the sarcoplasmic reticulum (SR) sandwiched between them (Fig. 2B). 

A nerve axon activating a particular muscle fiber is known as a motor nerve or motor neuron (Fig. 2A). This axon can in fact be just one branch of a large nerve that also interacts with many other fibers in the muscle. The set of fibers activated by a single nerve is known as a motor unit. Fibers in a motor unit need not be adjacent to each other, but may be distributed through a muscle. 

The muscle sarcomere contains the principal contractile proteins myosin and actin (Fig. 3A to C), which on their own can produce force and movement, together with a number of cytoskeletal and regulatory proteins. The latter include titin, C-protein (MyBP-C), tropomyosin, troponin, a-actinin, myomesin, M-protein, and so on. Some of these help to organize the myosin and actin filaments in the sarcomere, some to define the filament lengths and structure, some to regulate activity, and some to modulate the actin-myosin interaction when the muscle is active. 

Studies of the myosin head, the globular part of the heavy chain together with the ELC and RLC, were dramatically transformed when the isolated myosin head from chicken skeletal muscle myosin was crystallized and its structure solved using protein crystallography by Rayment et al. (1993b Fig. 4A). This showed that the head consists of a globular 

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Of course, some processes do not require a reactor, e.g., some oil refinery processes. Here, the design starts with the sepauration system and moves outward to the heat exchanger network and utilities. However, the basic hierarchy prevails. 

The hierarchical nature of process design has been represented in different ways by different authors. A hierarchy of decisions and a process design ladder also have been suggested. 

All too often safety and health (and environmental) considerations are left to the final stages of the design. Returning to the hierarchy of design illustrated by the onion diagram in Fig. 1.6, such considerations would add another layer in the diagram outside the utilities layer. This approach leaves much to be desired. 

Following this hierarchy, all to often safety, health and environmental considerations are left to the final stages of design. This approach leaves much to be desired, since early decisions made purely for process reasons often can lead to problems of safety, health, and environment that require complex solutions. It is better... 

To give some structure to the process design it is common to present information and ideas in the form of process flow schemes (PFS). These can take a number of forms and be prepared in various levels of detail. Atypical approach is to divide the process into a hierarchy differentiating the main process from both utility and safety processes. 

If a Pfaff differential expression DF = Xdx + Tdy+Zdz has the property that every arbitrary neighbourhood of a point P(x, y, z) contains points that are inaccessible along a path corresponding to a solution of the equation DF = 0, then an integrating denominator exists. Physically this means that there are two mutually exclusive possibilities either a) a hierarchy of non-intersecting surfaces (x,y, z) = C, each with a different value of the constant C, represents the solutions DF = 0, in which case a point on one surface is inaccessible... 

Successive n and n + 1 particle density fiinctions of fluids with pairwise additive potentials are related by the Yvon-Bom-Green (YBG) hierarchy [6]... 

The hierarchy of models is complemented by a variety of methods and tecluiiques. Mesoscopic models tliat incorporate some fluid-like packing (e.g., spring-bead models for polymer solutions) are investigated by Monte Carlo... 

Election nuclear dynamics theory is a direct nonadiababc dynamics approach to molecular processes and uses an electi onic basis of atomic orbitals attached to dynamical centers, whose positions and momenta are dynamical variables. Although computationally intensive, this approach is general and has a systematic hierarchy of approximations when applied in an ab initio fashion. It can also be applied with semiempirical treatment of electronic degrees of freedom [4]. It is important to recognize that the reactants in this approach are not forced to follow a certain reaction path but for a given set of initial conditions the entire system evolves in time in a completely dynamical manner dictated by the inteiparbcle interactions. 

Equations (169) and (171), together with Eqs. (170), fomi the basic equations that enable the calculation of the non-adiabatic coupling matrix. As is noticed, this set of equations creates a hierarchy of approximations starting with the assumption that the cross-products on the right-hand side of Eq. (171) have small values because at any point in configuration space at least one of the multipliers in the product is small [115]. 

I ask 3 Transform ( inherit ) local Taylor expansions from a upper hierarchy level to the next lower hierarchy level. 

Figure 1-6 illustrates this hierarchy in going from data through information to knowledge. 

Walking through the Hierarchy of Chemical Structure Representation... 

The representation of molecular surfaces, including the display of molecular surface properties, can be regarded as the next level of this hierarchy, but will be addressed in Sections 2,10 and 2,11 in this volume. 

Concentration on the types of bonds broken or made in a reaction provides a basis for reaction classification. We first show this only for one bond (Figure 3-14). On the first level of a hierarchy, a bond can be distinguished by whether it is a single, double, or triple. Then, on the next level, a further distinction can be made on the basis of the atoms that comprise the bond. 

In fact, there is a hierarchy in calculating molecular properties by additivity of atomic, bond, or group properties, as was pointed out some time ago by Benson [1, 2]. The larger the substructures that have to be considered, the larger the number of inaements that can be derived and the higher the accuracy in the values obtained for a molecular property. 

After the definition of a reaction type, a scheme for the evaluation of the given reaction type can follow in the reaction rule. An entire hierarchy of evaluations can be implemented, from no evaluation at all to a full-fledged estimation of reaction kinetics [12 ... 

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