JP3955129B2 - Interface structure and simulation apparatus for simulation - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an interface structure for simulation and a simulation apparatus.
[0002]
[Prior art]
A simulation may be performed to simulate the behavior of a factory or plant. By performing the simulation, for example, the operational efficiency of a factory or the like can be predicted, and the result can be reflected in the process or the like to improve the efficiency. Conventionally, various methods have been proposed as such a simulation method. This can be broadly divided into a continuous system model that simulates temporally continuous behavior and a discrete system model that simulates temporally discrete behavior. The continuous system model is a model that advances the time of a system at a constant time interval and tries to capture the behavior of the system.
[0003]
On the other hand, the discrete system model tries to capture the behavior of the system by looking mainly at events that occur irregularly. In this discrete system model, there are various simulation methods such as a three-phase approach, an event approach, and an activity approach, and the above phenomenon is called an activity or an event depending on these methods.
[0004]
In the above three-phase approach, a phase (hereinafter referred to as the B phase) for performing a time-dependent activity (Boundary Activity) that occurs due to a change in time and a system-dependent activity (Conditional Activity) that occurs due to a change in system status are performed. It has a phase (hereinafter referred to as C phase) and a phase for advancing the system time (hereinafter referred to as A phase). By repeating each phase in the order of B → C → A, a discrete event simulation is performed. Execute.
[0005]
For example, when considering the task of washing a car at the car wash, if the car wash ends in 10 minutes, the event “take out the car from the car wash after 10 minutes from the start of car wash” Since it is performed according to a change, it can be considered as Boundary Activity (B phase). Normally, the B phase is performed by registering and extracting (executing) events from the event list.
[0006]
When the B phase is executed, the system status may change accordingly, so the C phase is executed next. For example, since the event of “entering a car if the car washes are free” is performed according to the situation of the system, it can be considered as Conditional Activity (C phase). Next, in the A phase, processing for advancing the time to the event that occurs earliest from the present time among all the events registered in the event list is performed.
[0007]
The event approach is an effective technique for simulating a system including many time-dependent events. For example, when considering the train arrival / departure time problem, the train travel time between stations is known in advance, and the state of the entire system is determined using only the travel time as a trigger. Is possible. The activity approach is a simulation method that takes into account activities depending on the system status.
[0008]
In addition, there are simulation methods such as a process approach in the discrete system model.
As described above, there are various methods as a simulation method based on the discrete system model, and an optimum one is selected depending on what kind of system is handled. For example, an event approach is used for a system with few situation-dependent events, such as a simulation of train arrival and departure times, and a three-phase approach is used for a system with many situation-dependent events.
[0009]
[Problems to be solved by the invention]
However, a conventional discrete system model simulation apparatus has been made exclusively for one of various methods. Therefore, only those who are familiar with the specialized method can create or change the model of the system to be simulated. Even if it is familiar with other methods, it is familiar with the method specialized for the simulation device. Without it, it was difficult to carry out the simulation. Thus, the conventional simulation apparatus has a problem that it lacks versatility.
[0010]
The present invention has been made to solve such problems, and a multi-appropriate simulation apparatus capable of performing simulations by various methods such as a three-phase approach, an event approach, an activity approach, and a process approach, and therefore The purpose is to provide an interface structure.
[0011]
[Means for Solving the Problems]
The interface structure for simulation according to the present invention is an interface structure for performing simulation by discrete events, and among phases necessary for performing simulation by discrete events, a phase for advancing time, and time dependence Class and / or a phase for executing a system-dependent event, and a class abstracted in two phases, and the class is between a child class corresponding to a specific simulation method of a discrete system model Thus, a mechanism for inheriting the functions and properties of the class required in the discrete system model is provided.
[0012]
Another feature of the present invention is that, among the classes abstracted into the two phases, the phase for executing the event is realized by using polymorphism of object-oriented programming. .
[0013]
A simulation apparatus according to the present invention is a simulation apparatus for performing a simulation by a discrete event, and an execution unit for performing the simulation by a discrete event has a phase for advancing time, a time-dependent event and / or a system-dependent There is a class abstracted in two phases, a phase for executing an event, and this class is necessary in the discrete system model with a child class corresponding to a specific simulation method of the discrete system model. An interface structure having a mechanism for inheriting the functions and properties of the class, and executing the event in the execution unit to make a request to advance the time of the system .
[0014]
Another feature of the present invention is that, among the classes abstracted into the two phases, the phase for executing the event is realized by using polymorphism of object-oriented programming. .
[0015]
Another feature of the present invention is that it has a class for loading and saving objects separately from the abstract class.
[0016]
According to the present invention configured as described above, in the child class that belongs to the hierarchy below the abstract class that is abstracted into two phases of the part that determines which event is to be executed and the part that advances the time, the abstract The simulation is performed by inheriting the interface of the class, but since it applies to the two phases abstracted by many methods of the discrete system model, various simulation methods can be performed by inheriting the interface of the abstract class. A structure corresponding to can be made.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a main functional configuration of a simulation apparatus according to an embodiment of the present invention, and FIG. 2 is an object diagram showing an interface structure used in the simulation apparatus.
[0018]
In FIG. 1, reference numeral 1 denotes an event list, in which time-dependent discrete events (activities or events) to be performed when a simulation is performed are registered as a list. The way events are arranged on the list is in the order of the timing at which the events occur. In the following description, an activity is used as an example of an event.
[0019]
As shown in FIG. 1, in this embodiment, the Boundary Activity registered in the event list 1 is managed separately by dividing it into an initial activity list 1a and an activity list 1b. This is because, for example, when considering a simulation of a system in which a certain object is processed and output in several steps, the one that has not yet entered the system is separated from the one that has entered the system.
[0020]
That is, the initial activity list 1a is an activity related to an object given from the outside of the system to be simulated (for example, in the case of iron making processing at a steel company of a steel company, the slab is heated and transferred to a rolling mill by a moving table or the like. Activity related to the time when the slab is given from the outside). The activity list 1b is for registering an activity related to a scheduled processing time of an object to be processed in the system (for example, in the above-described example, an activity in which the heating process ends at a certain time).
[0021]
As described above, in this embodiment, the time-dependent boundary activity is divided into two lists and managed, for example, as a result of performing a simulation under a request to process a certain amount within a predetermined time, how many items are present. In order to know whether it has been left unprocessed, it is only necessary to look at the contents of the initial activity list 1a, which has the advantage of facilitating recognition.
[0022]
Reference numeral 2 denotes a base scheduler, which includes an event management unit 2a and a time management unit 2b, and executes a Boundary Activity by registering and extracting an activity with respect to the event list 1, and executes a process for advancing Conditional Activity and system time. The simulation is carried out.
[0023]
That is, the event management unit 2a performs both a time-dependent activity (Boundary Activity) and a system-dependent activity (Conditional Activity). Further, the time management unit 2b makes a request to advance the system time to the activity that occurs earliest among all the activities registered in the event list 1. Reference numeral 3 denotes a clock unit for expressing the time in the simulation, and advances the time in response to a request from the time management unit 2b. In the present embodiment, the clock unit 3 is provided outside the base scheduler 2, but can be provided inside the base scheduler 2 together with the time management unit 2b.
[0024]
Reference numeral 4 denotes a file management unit, which is a plurality of objects used in a series of simulations (refers to a module consisting of a set of data representing its own internal state and a unique method group for processing them in object-oriented programming). Load, save, etc. Also, loading and saving of condition data for simulation, intermediate data generated in the middle of the simulation, or final processing result data is performed.
[0025]
FIG. 2 is an object diagram showing an interface structure used in the simulation apparatus according to the present embodiment as described above, and shows a hierarchical structure of classes in object-oriented programming. In FIG. 2, the same functional blocks as those shown in FIG.
[0026]
As shown in FIG. 2, the base scheduler 2 is a parent class (a class refers to an object type having the same functions and properties in object-oriented programming), and a three-phase scheduler 21, an event scheduler 22, an activity scheduler 23, etc. A hierarchical structure is constructed with a scheduler corresponding to various methods as its child class.
[0027]
In this embodiment, the base scheduler 2 that is the parent class and the schedulers 21 to 23 corresponding to the respective methods that are the child classes have an inheritance relationship, and each of the schedulers 21 to 23 has the base scheduler 2. It inherits its functions and properties. Moreover, in this embodiment, the event management part 2a with which the base scheduler 2 is provided is comprised using the virtual function. A virtual function is a function that has the special property of redefining a function defined in a class with its child class and replacing it with a different function. This function uses the polymorphism of object-oriented programming. is there.
[0028]
That is, in this embodiment, the function defined by the base scheduler 2 is redefined by the schedulers 21 to 23 that are its child classes and replaced with functions corresponding to the schedulers 21 to 23. In the present embodiment, the functions defined by the base scheduler 2 are “a function for advancing time” and “a function for executing an event”.
[0029]
In other words, the “function for advancing time” selects an event to be executed earliest from a plurality of events, advances the time of the system to the time to execute the event, and executes that event. Is the “function to execute events”. In other words, any of the simulation methods of the discrete system model described in the conventional example can be divided into two phases: a part of which event is executed now and a part of advancing time.
[0030]
Therefore, in this embodiment, paying attention to this point, an abstract class having functions of these two phases is created, and among the elements necessary for the simulation, the time management unit 2b is made to advance the time part, All the parts for executing other events are made to be performed by the event management unit 2a.
[0031]
At this time, the base scheduler 2 behaves according to the simulation method implemented in the schedulers 21 to 23 by being configured with virtual functions. Since the base scheduler 2 has a function to execute both the Boundary Activity and the Conditional Activity, even if the scheduler that inherits the function of the base scheduler 2 is implemented based on many simulation methods of the discrete system model, it is appropriate. A simulation can be performed.
[0032]
That is, the simulation apparatus of the present embodiment has the interface structure as described above, so that when implemented as the three-phase scheduler 21, the event management unit 2a functions to execute both the Boundary Activity and Conditional Activity. . Further, when implemented as the event scheduler 22, it functions to perform only the Boundary Activity, and when implemented as the activity scheduler 23, it functions to perform only the Conditional Activity.
[0033]
As described above, according to the simulation apparatus of the present embodiment, the abstract class interface abstracted into two phases, that is, the part of which event is currently executed in the base scheduler 2 which is a virtual function and the part of controlling the time. As each scheduler inherits, a structure corresponding to various approaches can be made. That is, any discrete event simulation method such as a three-phase approach, an event approach, an activity approach, or a process approach can be supported.
[0034]
Furthermore, even if a completely new method for discrete event simulation is devised in the future, if the method falls within the framework of the abstracted class as described above, that method is also supported. be able to. As described above, the simulation apparatus according to the present embodiment has an advantage that it can cope with a new method devised in the future.
[0035]
As is clear from FIG. 2, in this embodiment, the file access unit 4 manages the classes to be accessed as a single file, and the base scheduler 2 class does not perform file access. Yes. By doing so, the structure of the base scheduler 2 is prevented from being changed by the file access method. The file management unit 4 can also be used in a general database.
[0036]
Since the structure of the base scheduler 2 is not changed by file access, the schedulers 21 to 23 which are child classes thereof can inherit the same functions and properties of the base scheduler 2. Therefore, any simulation method having two phases abstracted by the base scheduler 2 as described above can be implemented by the schedulers 21 to 23 regardless of file access.
[0037]
【The invention's effect】
As described above, the present invention creates a class abstracted into two phases, a phase for advancing time and a phase for executing an event, which are included in many simulation methods of discrete system models, and the abstraction thereof. Since the class is configured to have an inheritance mechanism with its child class, simulation corresponding to various methods can be performed by the child class inheriting the interface of the abstract class. Accordingly, it is possible to provide a multi-approach-compatible simulation apparatus that can perform simulations by various methods.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a main functional configuration of a simulation apparatus according to an embodiment of the present invention.
FIG. 2 is an object diagram showing an interface structure used in the simulation apparatus according to the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Event list 1a Initial activity list 1b Activity list 2 Base scheduler 2a Event management part 2b Time management part 3 Clock part 4 File management part 21 Three phase scheduler 22 Event scheduler 23 Activity scheduler

Claims (5)

An interface structure for performing simulation by discrete events,
Of the phases necessary for the simulation by the discrete event, the class is abstracted into two phases: a phase for advancing time and a phase for executing a time-dependent event and / or a system-dependent event The class has a mechanism for inheriting the functions and properties of the class required in the discrete system model with a child class corresponding to a specific simulation method of the discrete system model . An interface structure for simulation characterized by this.   The interface for simulation according to claim 1, wherein, among the classes abstracted into the two phases, the phase for executing the event is realized by using polymorphism of object-oriented programming. Construction. A simulation device for performing simulation by discrete events,
The execution unit that performs the simulation by the discrete event has a class abstracted into two phases, a phase for advancing time and a phase for executing a time-dependent event and / or a system-dependent event, Provided with an interface structure in which the class has a mechanism for inheriting functions and properties of the class required in the discrete system model with a child class corresponding to a specific simulation method of the discrete system model ,
A simulation apparatus characterized in that an event is executed in the execution unit and a request is made to advance the system time .   4. The simulation apparatus according to claim 3, wherein, among the classes abstracted into the two phases, the phase for executing the event is realized by using polymorphism of object-oriented programming.   5. The simulation apparatus according to claim 4, further comprising a class for loading and saving an object separately from the abstracted class.

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