Token flow

The data flow graphs are allowed to contain conditionals as well as loop constructs. A token flow semantics is responsible for a concise behavioral model, without the need for additional external control information. Having conditionals and loops coherently represented in the data flow graph allows synthesis programs to perform several global optimizations, uninhibited by block boundaries, as are imposed by most other representations. 

For internal use in the synthesis tools, simple and well-defined languages are highly desirable. The token flow model described above is particularly well suited for this purpose. 

The static test arc is marked by a directed dash line. In general, it is often used to replace the self-looping structure in PN. In other words, a static test arc is equivalent to two equally-weighted arcs pointing in opposite directions. Notice that this arc also does not allow token flow, i.e. the token quantity of its input place cannot be reduced by firing the output transition. 

Fig. 5.2. Changes that take place when an automobile moves in a thermally insulated environment at constant temperature Tq and pressure pt). The environment is token to be large enough that the change in system volume V2 - V, does not increase p, and the flow of heat Q across the system boundary does not affect Tq.

Two other, closely related, consequences flow from our central proposition. If the d orbitals are little mixed into the bonding orbitals, then, by the same token, the bond orbitals are little mixed into the d. The d electrons are to be seen as being housed in an essentially discrete - we say uncoupled - subset of d orbitals. We shall see in Chapter 4 how this correlates directly with the weakness of the spectral d-d bands. It also follows that, regardless of coordination number or geometry, the separation of the d electrons implies that the configuration is a significant property of Werner-type complexes. Contrast this emphasis on the d" configuration in transition-metal chemistry to the usual position adopted in, say, carbon chemistry where sp, sp and sp hybrids form more useful bases. Put another way, while the 2s... 

For these calculations, attention was limited to a temperature range of 950° to 1350°K, a pressure range of 300 mTorr to 7.6 Torr, and SiH4 mass fractions of 15 to 30% in H2. Under these conditions, the mass fraction of SiH2 formed was at most on the order of 10 3, so that the influence of the Yj s on the temperature distribution was small. To a good degree of approximation, the temperature was calculated to be linear. By the same token, the flow field which was easily calculated did not demonstrate any unique behavior. 

In C3, there are several possible relations between activities such as sequential activities, concurrent synchronized activities, and activities that model the communication between different organizational units or persons. Within the scope of the activity-driven approach, activities can be represented by places in a Timed Colored Petri Net thus, the tokens visualize the control flow, which again determines the activity sequence. 

Data values. A transition not only moves tokens through the net but also may change its value, because in many modeled processes, the content of the data is what is important. The suitability of a workflow system for a given purpose depends on its ability to represent the complexity of the data that must flow though the system in addition to providing access to the operations that need to work on that data. 

The pure substance is a colorless, syrupy liquid, which, when poured into H,0. sinks under it before mixing. It has a disagreeable, metallic taste, somewhat resembling tirat of tartar emetic. When token into the mouth it produces a tingling sensation, increases the flow of saliva, and bleaches the tissues with which it comes in contact It is still liquid at —80 (— 22 P.). It is very unstable, and, even in darkness and at ordinary temperatures, is gradually decom )osed. At 20 (68 F.) the decomposition takes place more quickly, and at 100 (212 F.) rapidly and with effervescence. The dilute substance, however, is comparatively stable, and may be boiled and even distilled without suffering decomposition. 

To receive the methods of the Nine Elixirs, the disciple throws golden figurines of a man and a fish into an east-flowing stream as tokens of his oath (shi) The same rite is performed to receive the method of the Golden Liquor ... 

Elementary devices are general reusable elements used to model complex devices by inheritance or composition. At this level, only material and energy balance equations are taken into account. In consequence, states of such devices are only dependent on input or output flows activity. As ports provide the corresponding flow variables, they are defined as token in order to build the most general element. So much a device owns ports, so much its Petri net includes port tokens. When a port token marks a hybrid place of a device, the associated flow variable is taken into account in the DAE system. The management of these tokens is done either with internal transitions (in the case of specialized device) or with command places (when the port status is dependent on the evolution of a another device). In order to preserve the model consistency, the output port activation has to activate in chain the input port of the above connected device. Figure 5 shows an example of elementary device found in PrODHyS. 

Each task of the parse tree, with the leaves representing source tokens and vertices representing semantic units, is mapped into a graph incorporating both control flow and data flow, with vertices representing primitive operations. Lifetime analysis is used to represent the data flow in single-assignment form. 

The DSFG basically models the data flow in an algorithm the vertices represent operations and the edges represent signal paths. The tokens, which are routed along the signal paths, are associated with data samples, produced and consumed by the operations. 

These two nodes are connected by arrows known as Arcs A, which show the direction of flow of tokens . Tokens are used to describe the state of the system, and are used to mark/enable a place as in Figure 2. 

While the physical properties of plastic products depend on molecular size, many products can tolerate 30% or so regrind content without an undue sacrifice in properties. By the same token, there are some products that cannot tolerate any regrind content they need the best properties they can get. Others can tolerate 100% regrind content and still provide acceptable performance. Also, we must recognize that the uniform addition of regrind will improve processability— the material flows more readily. 

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