Figure 5.34: Properties for the output node of the Placement object. This is all thats required to change the connection type. The utilization of a server (or group of parallel identical servers) is the time-average number of individual servers in the group who are busy, divided by the total number of servers in the group. Historical records show that approximately 59% of customers have faxed their prescriptions ahead of time and the times for a pharmacist to fill a prescription are triangularly distributed with parameters (2,5,8) minutes. Discrete-event simulation (DES) is moving down the same path. So our single-server model is just an implementation of the basic seize-delay-release logic illustrated in Figure 4.13. Error Percent: Percentage of the sample average below which the half-width of the confidence interval must be. You can also drag some windows (Search, Watch, Trace, Errors, and object Consoles) outside of the Simio application, even to another monitor, to take full advantage of your screen real estate. At this point, we have defined the new referenced properties and told Simio to use these properties to define the Initial Capacity properties for the three fine-pitch servers. \end{eqnarray*}\]. In the real system, wed like to send the PCB to the machine that will be available first. However, some property definitions can contain random variables and dynamic states that could return different values even though the definition remains constant. Since the make station has room for three employees to be making pizzas simultaneously, we set the Initial Capacity property to 3. accurately mimic your real life system. Consider the 95% confidence intervals for \(L\) based on five and 50 replications:
Figure 9.17: Controls for an experiment for Model 9-1. Properties are defined within an object (see Figure 5.2) to collect information from the user to customize that objects behavior (note that in this context, the term User refers to the person who instantiates the object and specifies its property values. All of these Simio and simulation-related topics will be covered in more detail in the subsequent chapters, with more interesting models. So in our 10-hour run, the output value of 0.0613 hours for average time in system is just the simple average of these 470 entities individual times in system. PCB assembly basically involves adding electronic components of various types to a special board designed to facilitate electronic signaling between the components. The Project Library includes the objects defined in the current project. . Because dynamic ranking rules must examine every entity each time a decision is made, when the queues are very large it might cause slower execution speed. Figure 9.4 shows the two add-on processes for the ExamRooms object. The Transfer step will immediately transfer the object to the node specified in the Node Name property (Output@TakeOrder, in this case). If you run the experiment from Problem 3 five (or any number of) times, you will always get the exact same results even though the interarrival and service times are supposed to be random. Create an experiment with the following conditions: Average time (in minutes) that parts spend in the system; The rate at which good parts are finished (in parts per hour); The rate at which parts fall-out from S3 (in parts per hour). This property allows us to make one or more state assignments when an entity either enters or exits the server; see Figure 5.17. However, in many modeling situations, entity inter-arrivals and service times dont follow nice exponential distributions. The boxing times are triangularly distributed with parameters 0.5, 0.8, and 1 minutes (the employee also cuts the pizza before boxing it). In Model 5-4, weve defined the following responses: You can see in Figure 5.38 that the current response values are displayed as the experiment runs. Simio is rapid modeling without programming so profits accrue sooner. The first method uses the Facility Window and Simio objects from the Standard Library (Section 4.2) . We then experiment a little with this model, as well as introduce the important concepts of statistically independent replications, warm-up, steady-state vs.terminating simulations, and verify that our model is correct. Figure 9.48: Processing add-on process for Server1. Simulation lets you separate the winning ideas from the losing ideas and optimize your business You could draw walls (see the Drawing ribbon), or add features like doorways and plants. Figure 9.39: Combiner object with one parent and two member objects in queue. The SetNode step for the newly created Pizza entity objects sets the destination Node Name property to Input@Make so that the objects will be transferred to the Make object. By varying the minimum and Figure 5.8: Excerpt of expression builder choices. Resource utilization includes ScheduledUtilization as well as UnitsAllocated, Random.Exponential(10)). One of the difficult aspects of modeling in 3D is drawing the physical components of your system. 2. While it does provide some statistical capabilities, like the confidence intervals and SMORE plots that weve seen (and a few more that well see in future chapters), Simio makes it easy to export the results of your simulation to a CSV file that can then be easily read into a variety of dedicated statistical-analysis packages like SAS, JMP, SPSS, Stata, S-PLUS, or R, among many, many others, for post-processing your output data after your simulations have run. We chose the latter option and changed the Processing Time property for the ATM to Random.Exponential(1). As such, you definitely want to know how to tell the model to track these types of user-defined statistics yourself. evaluation, and on the basis of the past evaluations which
A token carries a reference to both its parent object and its associated object (Figure 5.6). In either case the modeling process can provide Our uncertainty here stems from sampling uncertainty, and this is exactly is where Subset Selection Analysis comes into play, as discussed earlier in Section 5.5 in a smaller example than the one we consider here. Models 4-3 and 4-4 will demonstrate the use of a triangular distribution for the service times, and the models in Chapter 5 will demonstrate the use of many of the other standard distributions. Look at all properties that have been changed from their defaults (in Simio these are all bold and their categories are all expanded). Figure 9.23: Properties for the TC response. All tokens wait in a single allocation queue for a specific resource. When a patient arrives to a particular room (as specified in the Sequence table), the patient will seize the Doctor and/or Nurse resource(s) required for treatment. Youve already seen how this export to a CSV file can be done, in Section 4.2.3, from the Experiment window via the Export Details icon in the Pivot Grid window. The controls columns include the referenced properties that we created and used to specify the initial capacities of the three fine-pitch placement machine objects. Regardless of the reason for these differences, their existence just emphasizes the need to do proper statistical design and analysis of simulation experiments, and not just run it once to get the answer, a point that well make repeatedly throughout this book. RTFM - Read The (um, er) Friendly Manual. We also used the built-in Excel Chart Tools to superpose a linear regression line, and show its equation and \(R^2\) value, confirming the positive relationship between average time in system and server utilization, with about 45% of the variation in average time in systems being explained by variation in server utilization. When an entity requires service from the resource, the entity seizes some number \(s\) of units of capacity from the resource. If we want to continue searching for the single best configuration, we could repeat the previous process delete the scenarios in the most recent rejects group and run additional replications with the remaining scenarios. Its certainly possible (and common) that youre instead interested in the short-run system behavior during the transient period; for example, same-day ticket sales for a sporting event open up (with an empty and idle system) and stop at certain pre-determined times, so there is no steady state at all of any relevance. Simio Experiments allow us to run our model for a user-specified number of replications, where Simio guarantees that the generated random variates are such that the replications are statistically independent from one another, since the underlying random numbers do not overlap from one replication to the next. You can use any combination of these filters to narrow the choices to what you are looking for. I have a source several servers sink model. The process involves three steps for arriving customers reception / application; a vision exam; and a written exam. This video is part of a three-video module on Simio "Input Parameters", "Response Sensitivity Analysis", and "Sample Size Error Analysis". modeling. This will open the 3D Warehouse web page (https://3dwarehouse.sketchup.com) in your default web browser. the impact that it has on your overall system performance. The Tally step (see Figure 9.11 for the properties) records the waiting time for the patient (stored in the WaitingTime entity state). (the expected value of a triangular distribution with parameters min, mode, max is (min + mode + max)/3, as given in the Simio Reference Guide).
Home Work Chapter 2.docx - Question 1: What is the Models a 3-phase workstation with setup, processing, and teardown. Section 4.3 re-builds the first model with Simio Processes rather than objects. Simio and Simulation - Modeling, Analysis, Applications - 6th Edition. Notice that the report includes the UserSpecified category including the CurrentWIP and TimeInSystem statistics. Finally, switch back to the Facility Window and set the run parameters (e.g., set the Ending Type to a Fixed run length of 1000 hours). Hopefully we can clear up the natural confusion as we develop models with more and more features/components and discuss the use of their properties and states. If you set the add-in, the current undo history will be cleared. Table 5.3 gives the results based on the same run conditions as our verification run. Although there are many simulation products on the market, we believe only Simio meets these three Since the response values shown in Figure 9.24 are sample means across ten replications of each scenario, they are subject to sampling error. Naturally, the next question should be Is this really the truly optimal solution? Unfortunately, the answer is that were not sure (actually, we do know that this is not the optimal solution for this problem, but we cheated a bit described below and we will not know the answer in general). Sometimes a new property will appear to get lost. Make sure that youre looking in the properties window of the same object to which you added the property (e.g., if you add a property to the ModelEntity object, dont expect to see it appear on the Model object or a Server object). Figure 9.9 shows the properties for the first and second Assign steps in the TreatmentRooms_Processing add-on process. Remember that we identified \(51,030\) possible configurations for our system and that we limited OptQuest to testing 100 of these. By increasing the number of replications (samples), we can make the half-width increasingly small. Table 4.1 lists the objects in the Simio Standard Library. We removed the Escort Type column as we are no longer modeling the physical movement of patients and staff. You select objects from libraries and In Model 9-2 we will also consider a related resource allocation problem. The process logic can refer to properties, states, and functions of both the parent object and the associated object. The model is used to verify that the system will perform as expected. In addition, most simulation software, including Simio, automatically records queue, resource, and entity-related statistics as the model runs. With this configuration for all of our stations, an entity can only be transferred from one Server to the next if the number of entities in the internal queue representing the input buffer of the subsequent station is less than the value of the referenced property BufferCapacity. More comprehensive simulation products have built-in ABC. Similarly, the Output Buffer is used to hold entities that have completed processing on the server, but do not yet have anywhere to go. So based on the TakeOrder object properties and the Input_TakeOrder_Entered add-on process a maximum of one employee can be taking an order at any time and the number of customers waiting on hold is determined by the value of the NumLines referenced property. This is done using the Tally step (as shown in Figure 5.19). To support our experimentation, we used referenced properties to specify the number of phone lines (NumLines) and number of employees (NumWorkers). a wide range of systems. Since reworked boards are sent back to the placement machine for processing, we connected the output node of the Rework object to the input node of the Placement object.
1. SIMIO Single Server Model Build a model to | Chegg.com With Simio you can employ multiple modeling paradigms and The entity in your model should now look similar to that in Figure 4.35. Simio provides capabilities for logging various data during interactive runs and using this data to create dashboard reports. Its thus possible that the output values you get when you run our examples interactively may not always exactly match the output numbers were showing here, which we got as we wrote the book. Branching is modeled by having two connectors originating at the same output node (boards leaving inspection are transferred to either the GoodParts sink or the BadParts sink). Wed like a Poisson arrival process at rate \(\lambda = 48\) entities per hour, so well specify that the entity interarrival times are exponentially distributed with a mean of 1.25 minutes (a time between entities of \(= 60/48\) corresponds to a rate of 48/hour). Try to look at the problem from a totally different direction. Simulation lets you see the impact of change. The Pivot Grid format is extremely useful for finding information when the output includes many rows. A function is a value thats internally maintained or computed by Simio and can be used in an expression but cant be assigned. Figure 9.12 shows the model output statistics and Figure 9.15 shows the properties for the Satisfaction output statistic where we compute the proportion of satisfied patients. Use Trimble 3D Warehouse to find appropriate symbols for the entities (steel plates) and the server (a drill press or other hole-making device). The corresponding properties for the Exam Capacity, Treatment Capacity, Trauma Capacity, and Nurse Capacity controls are set similarly. is a numeric value distributions. This way, the first station will never be starved (this is equivalent to saying that there is an infinite supply of raw materials for the line). We then did further experimentation with the scenarios in the possible best subset. Discrete States are used to record numerical values. Finally, well demonstrate two different methods for recording the tally values: Using an add-on process to record the value of the TimesProcessed state to the tally statistic; and using the Tally Statistics property of the input node of the Sink object (ordinarily, youd use one method or the other in a model, but we wanted to demonstrate both methods for completeness). Figure 9.5 shows the DoctorNurse list and the details of the Seize step. Our interest is in the typical queueing-related metrics such as the number of entities in the queue (both average and maximum), the time an entity spends in the queue (again, average and maximum), utilization of the server, etc. You might want to leave this enabled as a reminder until you get familiar with the interface. Compared to the Pivot Grid we saw while running in Interactive Mode (Figure 4.9), we see the additional results columns for Minimum, Maximum, and Half Width (of 95% confidence intervals on the expected value, with the Confidence Level being editable in the Experiment Design Properties), reflecting the fact that we now have five independent observations of each output statistic. Clearly this would be a poor estimate, regardless of the individual roll. As such, we need to request that the Worker object travel to BasicNode2 (the node in the WorkerNetwork designated for the make station). Simio and most other simulation packages can sample from a wide variety of distributions to support general modeling. ), you should answer No, make a copy of the model, and open the copy to set up for OptQuest. While we could have extended Model 8-3 by adding the patient treatment and performance metric components to that model, we chose to create an abstract version of the model by removing the worker objects and transportation paths and using Connector objects to facilitate entity flow. In the case of the Server in the Standard Library, the Process Logic category is initially expanded, and all others are initially collapsed. Destroys entities that have completed processing in the model. Depending on the characteristics of the system being modeled (the expected server utilization, in our case), the distribution and expected value of queue times for the third, fourth, fifth, etc.entities can be significantly different from the distribution and expected value of queue times at steady state, i.e., after a long time that is sufficient for the effects of the empty-and-idle initial conditions to have effectively worn off. The path lengths and entity speed can be easily modified as dictated by the system being modeled. Note that when we defined the user statistic to track the numbers of times boards are processed by the placement machine (Section 5.3.1), we used an entity state rather than a model state. States do not appear in the Properties Window, although a Property thats used to designate the initial value of a State often does appear in the Properties Window. For our simple model, we need to specify probability distributions governing the interarrival times and service times for the arriving entities. However because properties cant change their values during a run, those property values are efficiently stored once, with the instance, regardless of how many dynamic entities (Runspaces) are created as the model runs. Your model should look something like Figure 5.7. Once all Pizza entities complete processing at the Box station, the Customer Order and Pizza entities for an order are combined and the order is complete. Both of these enhancements are commonly used and are quite easy in Simio. 2000 x ExamCapacity +
102 USING A SINGLE SERVER TO MODEL MULTIPLE RESOURCES . The steps are as follows: Figure 4.30: Initial dialog box for the new dashboard report. Drag the Duration (Hours) item and drop it on the Values (Pane 1) data item. The exported data file is in CSV format, which can be read by a variety of applications, such as Excel. To enter this in the expression builder begin typing Random. and other performance measures in your system. Another example is that all objects that are resources have a function named ResourceState which returns a number for its current state. Watch provides a way to explore the system state in a model. Now that we have servers where the resource capacity changes over the model run, the utilization calculation is a bit more difficult in fact, the interpretation of utilization itself is no longer straightforward. Many design-time and experimentation windows and tabs (for example the Process window or individual data table tabs) can be changed from their default positions by either right-clicking or dragging. Now that we have completed Model 4-3, we must verify our model as discussed in Section 4.2.5. Name the object instances in your model using meaningful names. Recall that the expected uptime for the placement machine is 6 hours and the expected time to repair it is 30 minutes. Ignoring the machine failures for now, wed expect the utilization of the placement machine to be \(13.514 / 15 = 0.9019\). gives the number of entities that exit the FinepitchFastStation object. Note the use of the OrderNumber entity state set off by braces. Since the make process also requires an employee, we will use the Processing add-on process to seize the Worker object and the Processed add-on process to release the worker as we have done previously with the TakeOrder object. Youll see examples of using referenced properties in the models in the current and subsequent chapters. First select the input node of the BadParts sink and expand the Tally Statistics property group (shown at the top of the figure). B what is the server utilization rate 3 pts sol 8 0. Note that since we defined referenced properties for the station processing times (ProcessingTime) and the buffer capacities (BufferCapacity), these show up as Controls in the experiment. As mentioned above, most Simio models that you build will use the Standard Library objects and its unlikely that youll build complete models using only Simio processes. Our interest here is in the Buffer Capacity section of the properties and the Input Buffer and Output Buffer properties in particular. If youre new to object-oriented approaches, the fact that a model is an object definition probably seems a bit strange, but hopefully once you gain some experience with Simio, it will begin to make sense. 2005) or (Law 2015)). The most common initial reaction to a bug is to assume it is a software bug. Begin typing Math and enter a period to complete the word and provide a list of all available math functions. More sophisticated capability allows conditional breaks such as for the third entity that reaches point A or the first entity to arrive after time 125. Basic break functionality in Simio is found by right-clicking on an object or step. your model. Again, we could delete the sample schedule and create a new schedule, but this time well just change it to meet our needs. But often there is need to measure the operating cost of one scenario versus another. & Satisfaction \ge 0.8,
Figure 9.46: Facility view for Model 9-3. Scrolling down to the TimeInSystem - Average (Hours) heading on the left will show a Value of 0.06126, the same (up to roundoff) as we saw for this output performance measure in the Pivot Grid in Figure 4.9. If the requested resource isnt available, the token (and associated entity) must wait. In order to model the allocation of exam/treatment resources to patients, we will use Add-on Processes (see Section 5.1.4.1) associated with the respective room resources. One of the powerful features of Simio is that whenever you build a model of a system, you can turn that model into an object definition by simply adding some input properties and an external view. Well also assume that, for multi-shift processes (inspection, in our case), a workers first hour is spent doing paperwork and setting up for the shift, so that theres only one worker actually performing the inspection task during those periods when worker shifts overlap. A state in the Runspace for a dynamic object (e.g., an entity) may be referenced using the terminology InstanceName[InstanceID].StateName. In such a case, Simio provides an Add-In, Select Best Scenario using KN, available under the Select Add-In icon on the Experiment ribbon, to narrow things down for you; again, this is based on means. Well revisit this topic in more detail in Section 5.1.4, but for now well return to our initial model using the Standard Library objects. Table 9.2 gives the weekly resource costs that well use. Figure 9.9: Assign step properties for adding the second entity wait component. Consider a pharmacy where customers come to have prescriptions filled. As we have seen, the standard Source object will create entities using an interarrival time distribution or an arrival schedule. Look at all properties that have not been changed from their defaults. When you first load Simio youll see either a new Simio model the default behavior or the most recent model that you had previously opened if you have the Load most recent project at startup checkbox checked on the File page. In the description of Model 5-3, we indicated that as part of our model verification, we had predicated the proportions of parts that would go to the fast, medium and slow fine-pitch placement machines (38%, 33%, and 29%, respectively). Modify the model so that the inspectors. Simulation lets you validate proposed designs and make the best use of your limited The first Assign step makes the following state assignments: Figure 9.35: Properties for the NumberOrdered model state. As before, we can either declare that we have four good configurations, or do additional experimentation.
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