Программное обеспечение баз данных. Архитектура клиент-сервер
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e either static , the main difference between continuous and discrete event modeling is what is being modeled and how time is handled.simulations are analogous to a constant stream of fluid passing through a pipe. The volume may increase or decrease, but the flow is continuous. In continuous models, values change based directly on changes in time. These values reflect the state of the modeled system at any particular time, and simulated time advances evenly from one time-step to the next. For example, an airplane flying on autopilot represents a continuous system since changes in state (such as position or velocity) change continuously with respect to time. The time line for a continuous model is evenly spaced.event 's continue with the pipe analogy. For discrete event simulations, the pipe could be empty or have any number of separate buckets of water traveling through it. Rather than a continuous flow, the buckets would come out of the pipe at random intervals. Events occurring at the other end of the pipe and within the pipe would determine what comes out and when.discrete event models, discrete entities change state as events occur in the simulation. Orders arriving, parts being assembled, and customers calling are examples of discrete events. The state of the model changes only when those events occur; the mere passing of time has no direct effect. A factory that assembles parts is a good example of a discrete event system. The individual entities (parts) are assembled based on events (receipt or anticipation of orders). The time between events in a discrete event model is seldom uniform.discrete event modeling considers its elements to be individual entities that can hold attributes, you could specify the experience level of different groups of employees, track parts by type, or route sales orders to specific departments depending on whether a customer wants custom or standard products.
Combinedapplications (such as Extend) can model systems either discretely or continuously. These hybrid applications combine all the features of both types of modeling. Some systems, especially when a portion of the flow has a delay or wait time, can be modeled as either discrete event or continuous. In this case, you choose how to model the system based on the level of detail required. Discrete event models provide much more detail about the workings of a system than continuous models do.discrete or continuous, the field of modeling is a fascinating one. Simulations have played important roles in numerous areas for a long time. Expect to see them combine with intelligent technology to produce exciting applications for the economies and the industries of the future.
FactorContinuous modelingDiscrete event modelingWhat is being modeled?Flows.Items.CharacteristicsRandom number "simulates" characteristics of flows and must be repeated for each query or junction.Characteristics are assigned to items by attributes and priorities which can then be tracked throughout the model.Time stepsInterval between time steps is usually constant. Model recalculations are sequential and time dependent.Interval between steps is dependent on when events occur. Model only recalculates when events occur.OrderingFlows are in FIFO order.Items can flow in FIFO, LIFO, priority, or customized order.RoutingFlows need to be explicitly routed by being turned off at one branch and turned on at the other (flows can go to multiple places at the same time).Items are automatically routed to the first available branch (items can only be in one place at a time).Statistical detailOnly general statistics about the system: amount, efficiency, transit time.In addition to general statistics, each item can be individually tracked: count, utilization, cycle time.Common usesScientific (biology, chemistry, physics), Engineering (electronics, control systems), Bulk processes, Systems thinking, Economics, Systems dynamics.Manufacturing, Service industries, Business process reengineering, Strategic thinking, Networks (computer, phone), Systems engineering.Recommended packageExtend CP Definedis a powerful tool for analyzing, designing, and operating complex systems. It enables you to test hypotheses without having to carry them out, saving you thousands, even hundreds of thousands of dollars! is a cost-effective means of exploring new processes, without having to resort to pilot programs. Simulation provides a method for checking your understanding of the world around you and helps you produce better results faster. And it is an efficient communication tool, showing how an operation works while stimulating creative thinking about how it can be improved.Modelsmodel is a logical description of how a system performs. Simulations involve designing a model of a system and carrying out experiments on it as it progresses through time. For example, the board game Monopoly is a model of a real system- the hotels and facilities of Atlantic City. When you play Monopoly, you are simulating that system. Simulation with Extend means that instead of interacting with a real system, you create a model which corresponds to it in certain aspects.can use a model to describe how a real-world activity will perform. Models also enable you to test hypotheses at a fraction of the cost of actually undertaking the activities which the models simulate. For example, if you are a hardware designer, you can use Extend to simulate the performance of a proposed system before building it.of the principal benefits of a model is that you can begin with a simple approximation of a process and gradually refine the model as your understanding of the process improves. This step-wise refinement enables you to achieve good approximations of very complex problems surprisingly quickly. As you add refinements, your model becomes more and more accurate.Simulation is Importantprovides a method for checking your understanding of the world around you and helps you produce better results faster. A simulation program like Extend is an important tool that you can use to:
Predict the course and results of certain actions.Understand why observed events occur.Identify problem areas before implementation. Explore the effects of modifications. Confirm that all variables are known. Evaluate ideas and identify inefficiencies.Gain insight and stimulate crea
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