Synchronized execution

An important point is the synchronized execution of the automata Ri, Pi and Ri- They obviously share the same signals/(Ti) and s(T2). In order to ensure correct execution, it is important that both transitions enabled by/(Ti) are taken at the same time. For the same reason, both transitions enabled by s(Ti) must be taken synchronously. Both signals act in this context as synchronization signals. Synchronized transitions share the same synchronization signals and thus must be taken at the same time. Evolutions in which one of them is taken alone are not possible. Note that many implementations of TA support binary synchronizations only. 

The relationship between the total duration of the project and the number of organizations involved - in the present case identical to the number of persons - was analyzed in simulation runs. The analysis was restricted to the simple case that a single activity is executed by a single person. Further extensions of the simulation model will allow for the synchronous execution of single activities by several persons. 

At this stage, an auto-synchronizing relay (Relay Code 25) is brought into the circuit. This relay is suitable for any size of a generating unit to be synchronized automatically with another unit or an infinite bus. The relay executes three basic functions ... 

Programming languages for the LCAP systems comprises traditional FORTRAN and FORTRAN-like directives which are interpreted by a precompiler developed in our laboratory. The directives provide syntactical constructs for interprocessor communication and synchronization. A detailed description of the implementation of our quantum chemistry package HONDO has been given elsewhere. (Dupuis, M. Watts, J. D. Theor. Chim. Acta, in press.) Our experience indicates that the calculations done in the study described above were executed in parallel at a very high level of efficiency. 

The master thread performs all the intemode communication using MPI. Only the action of the kinetic energy operators, Tr and Tr implemented with the DFFD approach, require such communication. While the master thread is executing the communication part and storing its results in hpsbuff, other threads perform local work storing results in the main array hps local. The use of the two separate arrays is needed to avoid having to synchronize the threads. Moreover, if the communication part finishes before the local part, the master thread joins the other threads in the computation of the local part. 

Once both local and communication parts of the Hamiltonian evaluation are finished, we add the buffer hpsbujf contmmng results of the communication part to the main array hps local. However, it is necessary to ensure that this addition will not start before both local and communication parts are finished. A barrier directive forces all the threads to synchronize. A thread that has reached the barrier will not resume execution until all other threads have reached it too. 

In a synchronous system, the state following 1110 would be 0101, with a synchronous change of the values of three variables. In addition to being unrealistic, this attitude prevents any choice between two or more possibilities each state cannot have more than one possible next state. We reason rather1 that, usually, either of the orders will be executed, thus leading in the present case to either of three possible next states ... 

Please note that all getters in the EntityDictionaryManager have a synchronized block. This block makes sure that when a load method is being executed, all its getter counterparts are on hold. You may wonder why none of the load methods are synchronized. This is because the load methods are all private and therefore cannot be invoked other than the EntityDictionaryManager, and all invocations inside the EntityDictionaryManager are enclosed in a synchronized block. This is why the loadEntityDictionary method is synchronized as follows ... 

The complete control system for positioning on an actual control axis includes several levels of control loops, which are acting in a synchronized manner, as shown in Figure 3.155. The intermediate control loops are called embedded loops, and together they guarantee that the original command for a specified movement is correctly completed. Any command for a movement, which is executed under closed-loop control, will result in a motion profile. This, usually trapezoidal profile, defines the way how the component is intended to be moved. 

The third core connector is the synchronous communication, it connects activities whose execution requires communication between the actors involved (e.g., during project meetings). 

More complex relations between activities can be modeled by means of the synchronization bar. One possible usage is depicted in Fig. 2.15 a). Here, two synchronization bars indicate the beginning and ending of two independent control flows to be followed in parallel. Both activities Al and A2 are executed. 

The second step of the construction phase (find possible rule applications) determines the integration rules that are possibly applicable for each half link. A rule is possibly applicable for a given half link if the source document part of the left-hand side of the synchronous rule without the context increments is matched in the source graph. The dominant increment of the rule has to be matched to the one belonging to the half link. For potential applicability, context increments are not taken into account, because missing context increments could be created later by the execution of other integration rules. For this reason, the context increments are matched in the selection phase before selecting a rule for execution. 

Likewise, rules had to be hand-coded in Lefering s framework. In contrast, synchronous triple rules are converted automatically into specific rules for execution in our approach. 

Both parallel processes in the Design Department and the Plastics Engineering Company can be inter-connected (Fig. 3.92). According to the plan of the process manager in the Design Department, the two simulation tasks Simulate Extraction and Simulate Distillation shall be synchronized with the task Determine Process Parameters of the other organization with respect to their execution states and documents shall be transferred between these tasks. This is an example of inter-organizational control and data flow. 

Loosely coupled processes. Processes are executed in parallel in different organizations. Occasionally, they interact at pre-defined communication and synchronization points. 

The simulation model was implemented using the Java-based high level Petri net simulator Renew [796, 797]. Renew is a tool for the development and execution of object-oriented Petri nets. It provides synchronous channels and seamless Java integration for easy modeling. 

There is a further influence of the synchronous communications on the project duration. Synchronous communications between the activities occupy the required persons of the participating organizational units. Employees are picked from the activity network and scheduled for the discussion by the simulation model. These employees cannot execute other activities during this time. Such communication relationships are a characteristic for design processes, and therefore their effect should be examined more carefully in future. 

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