Different types of networks

Within Wide-Area Networks (WAN) computers are connected over long distances via public telecommunication lines provided by national PITs. WANs are especially useful to access host computers with large databases, e.g. for the retrieval of bibliographic information. Another use of WANs are internationally operated electronic mail systems. 

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Many different types of networks have been developed. They all consist of small units, neurons, that are interconnected. The local behaviour of these units determines the overall behaviour of the network. The most common is the multi-layer-feed-forward network (MLF). Recently, other networks such as the Kohonen, radial basis function and ART networks have raised interest in the chemical application area. In this chapter we focus on the MLF networks. The principle of some of the other networks are explained and we also discuss how these networks relate with other algorithms, described elsewhere in this book. 

Different types of networks have been developed. The connection pattern is an important differentiating factor, since this determines the information flow through the network. 

To determine the structure of these different types of networks we have extensively studied (Ref. 1 and unpublished work) the diffusional behaviour of materials within these concentrated solutions. These diffusants are used in trace quantities so that they do not perturb the physicochemical properties of the network. By varying the size of the diffusional probe a good deal of information can be obtained about the structure of the network due to the hindrance effect the latter exerts on the diffusant. 

The epoxy resins [62,63] are formed from the chemicals indicated in Table 8. The different types of networks that can be obtained are outlined in Fig. 92. 

Fig. 92 Representation of the different types of networks a DGEBA/HMDA, b DGEBA/ HA and c DGEBA/DMHMDA...

Living polymerizations (2.3.1, Fig. 2.2) exhibit a different type of network growth. They are classified among the chainwise polymerizations because it is always the monomer that reacts, adding to growing chains. But the growth of primary chains occurs smoothly, as in the case of stepwise polymerizations. 

For a given material, there are generally several possible mechanisms of yielding and fracture, each characterized by the influence of temperature, loading rate, hydrostatic pressure, time (physical aging). A vast literature deals with the influence of network structure on yielding or on fracture properties, but we have to be very careful with the results obtained because of the different types of networks used in these experiments. 

The relative contribution of each of these types of network junctions to the overall crosslink density in silica-filled PDMS was estimated by means of T2 relaxation experiments [113, 118-121], To determine the relative contributions of the different types of network... 

The apparent number of monomer units between different types of network junctions in bound rubber is shown as a function of the volume fraction of Aerosil in Fig. 11 [14]. 

Furthermore, the plot of modulus vs. cross-link density (Fig. 20) suggests the existence of two different types of network in the case of (V)-EPTM and ENB-EPDM. The network obtained from EPTM curing appears more rigid on the basis of the tensile properties values and this evidence agrees with a possible cross-link functionality higher than 4 as a consequence of the existence of conjugated unsaturations in EPTM ... 

Software. Neural network shells usually contain graphics capabilities for illustrating unit activity. In general, their cost is directly related to the number of different types of network models they support. 

Fig. 3 Schematic representations of some possible supramolecular liquid crystalline polymer architectures, a-e Different classes of main-chain structures, f-i Different side chain polymers, j-m Different types of networks...

The oscillatory behavior of microtubules in solution is related to their dynamic instability [21,22]. During the cell cycle microtubules must undergo a cyclic reorganization between different types of networks (e.g., the cytoskeleton of interphase and the mitotic spindle) which involves the periodic disassembly and... 

Classification of networks by type may help significantly in selecting the solution for a specific application. Obviously, different types of networks are designed to serve different types of application needs. 

Table 5 Comparsion of Ox and Oy errors of last points in different types of networks, variations are given in %...

In all of the devices mentioned above, the polymer network is used to influence the alignment of the liquid crystal, sometimes to stabilize order, other times to introduce disorder. Different types of network structure are desired in each case. Since these polymer networks seem to advantageously alter the electro-optic properties of many types of liquid crystal displays, it is imperative to understand the structure of these polymer networks for modifying, ftirther improving, and even developing entirely new types of liquid crystal displays. 

Different types of network filters can be considered, aimed at minimizing specific harmonic spectrums. 

Third, we will not discuss every type of ANN, nor list every learning rule, transfer frunction, etc. that has ever been used. It is impossible to do this because variations on a theme (and there are many themes here) are constantly being developed. We have, however, compiled rather extensive lists of learning rules and useful functions. We have tried to discuss all of the different types of network for which we have found referenced chemical applications. We have also included some networks for which we found no applications but believe offer strong potential for solving chemical problems. Some network types, particularly backpropagation, have many variations for some of these variations we have limited our discussion and simply given a reference. 

Rg. 10,22 Two fundamentally different types of networks cross-linked by helices (a) multiple association of single helices, (b) association by multiple helices. (Reprinted with permission from Ref. [67].)... 

Abstract The nonlinear viscoelastic behavior of cured rubber is quite different from that of uncured compound, since the presence of crosslink networks. The factors for the influence of the crosslink networks on the nonlinear viscoelastic behaviors of cured rubbers are very complex and obscure. One of the reasons is that the crosslink networks may be consisted of several different types of networks. However, there are few literatures reporting the nonlinear viscoelastic behaviors of cured mbbers with mutle-networks. We reviewed the literatures dedicated to the topic of the non-linear viscoelasticity of simplest mutle-networks—double-network and summarized the useful information as much as possible in the present paper. Song s transient double-network model, double-network formed by twice curing and the specific crosslink network formed in metal salts of unsaturated carboxylic acids reinforced rubbers are introduced in detail. 

The problem facing the enterprise as whole is that the proliferation of distributed systems may result in different database management systems. The use of so-called relational models and the structure query language (SQL) for data access and retrieval will simplify the interface problems. If the proper software is used, these distributed databases will appear as if they were a single information source. A user will be able to get the information he or she needs without having to know where the data are stored. Furthermore, such software will run under different types of network protocol, media, and operating systems. 

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