MODSIM Lesson Midterms PDF

Lesson 1: Basic Simulation Model Concepts A problem statement is a clear description of issue/s, it includes a vision, issue statement and method Basic Simulation Model Components us...

Lesson 1: Basic Simulation Model Concepts A problem statement is a clear description of issue/s, it includes a vision, issue statement and method Basic Simulation Model Components used to solve the problem. Entities Formal Problem Statement Something that change the state of the First step in problem formulation process. This systems. Entities do not necessarily have to be people; phase determine if simulation is the appropriate tool to they can also be objects. analyze the study under consideration. Queues Simulation term for lines. Why do we need to write a Problem Statement? Resources Increase customer satisfaction This processes or serve the entities that are in Increase throughput the queue. For example; idle or busy. Reducing Waste Reducing work in process Simulation Event Lists Tools for Developing the Problem Statement Keeping track of the different things that occur during a simulation run. Anything that occurs during the Fishbone Chart simulation run that can affect the state of the system is Known as the cause-and-effect diagram, man- defined as an event. machine-material chart, and an Isikawa chart. This chart is to identify the cause of the problem or effect in interest. The head of the fish is labeled with the problem Measures of Performance Statistics or effect and each major bone is a possible source or cause of the problem. System Time System time is an observational output measure. Total amount of time that an entity spends in the system. Queue Time Queue Time is an observational measure. It is similar to system time, except it accounts only for the time that an entity spends in the queue. Time-Average Number in Queue A time-dependent statistics. The time-average number in queue is not directly a function of the number of entities that have been processed through the queue. Pareto Chart Utilization Pareto chart is a second technique to develop the problem statement. The concept of Pareto chart was A time-dependent statistics. The idle state developed by Italian economist Wilfredo Pareto. This is corresponds to a resource utilization level of 0, and busy frequently referred to as the 80-20 rule. This states that state corresponds to level of 1. 80% of the problem is caused by 20% of the factors. Lesson 2: Problem Formulation Problem Statement Orientation Project Management is a methodical approach to identify the cause of an incident and manage the life Second step in problem formulation. It involves cycle of all problems. familiarizing with the system. To familiarize, you must revisit the system keeping in mind how the system should be modeled and analyzed with respect to the nuances associated with simulation modeling. Project Manager Organized, passionate, and goal-oriented who understands what projects have in common, and their Orientation Process strategic role in how organization succeed, learn, and change. Initial Orientation Visit This is to obtain a high-level understanding of the basic inputs and outputs of the system. This type of Project Management Concepts orientation is typically conducted as a guided tour by a member of the commissioning organization. Project Parameters Detailed Flow Orientation Visit Time Parameter This is to gather detailed information on the Time Parameter is associated with the operation system. schedule. Most frequently implemented as a Gantt Chart. Gantt chart is a horizontal bar chart on which each Review Orientation Visit bar represents the sequence and duration of a different task in the project. This is the time to return to the system for the review orientation visit. This is to ensure that the Cost understanding of the system operation is consistent with the practitioners’ understanding of the system. The budget associated with the project. Performance Decision-Making Tools for Determining Project Problem statement phase of the project. These Objectives objectives may require that the simulation model be used to make operational or capital investment Brainstorming decisions. Generate a storm of ideas that are created by being exposed to other ideas. Project life Cycle Nominal Group Techniques Conceptual Determine the most important project objectives. This is by nominating or voting the most This involves the initial decision by someone in optimal project objective in the brainstorming. the organization to consider conducting the simulation study. During this phase, the organization will formally Delphi Process assign the project to the project manager. The problem formulation process may be completed during this life This process is like nominal group technique cycle phase. but all voting is conducted anonymously after the brainstorming session has concluded. Planning The project manager will identify all of the project team members. The simulation-planning phase Lesson 3: Project Planning activities involve the work breakdown structure, linear Project Management responsibility chart and Gantt chart. Execution Ways to Plan a Simulation Project Most of the simulation project activities for the Work Breakdown Structure (WBS) project will be completed during the execution life-cycle phase. These include the system definition, input data Successively lower division of project tasks collection and analysis, model translation, verification, into sub tasks. validation, experimentation, and analysis. Completion The completion phase activities are normally conducted after most of the technical project activities have been concluded. These activities are associated with turning over the results of the project and primarily include the simulation project report and presentation activities. Project Stakeholders These are the individuals or organizations who have some sort of vested interest in the ongoing operations or completion of the project. Internal Stakeholders Individuals who are directly associated with the simulation project team. This can also be interpreted as individuals over whom the practitioner/project manager exercises some degree of control. Linear Responsibility Chart (LRC) Practitioner/Project Manager This shows who participates in each activity Analyst and to what degree. Statisticians Data Collectors Functional managers who supervise the project team. External Stakeholders Individuals or organizations who are not directly associated with the simulation project team. Software vendor/developer Regulatory agencies Competitors Public or community public Problem Manager Functions Planning Organizing Motivating Directing Controlling  Lesson 4: System Definition Systems Classifications Discrete vs Continuous vs Combined Systems Combined event models contain both discrete and continuous components. Combined event systems are typically the most difficult type of system to model. Terminating vs Nonterminating System Terminating simulation which is where a simulation starts at a defined state or time and ends when it reaches some other defined state or time. Nonterminating or ready-state simulation is one in which the steady-state behavior of the system is being analyzed. This means that the simulation never ends nor does it mean that they system being simulated has no eventual termination. High-level Flowchart Basics An essential tool for defining the system is a high-level flow chart. It helps to obtain a fundamental understanding of system logic. It graphically depicts how the major components and events interact. This illustrates how the input and output data play a role in the Gantt Chart model. This illustrates the durations and relationships among different project activities. Standard Flowchart Symbols Oval Define the start and end process. Rectangle Represent general-purpose processes that are not specifically covered by any of the other flow chart symbols. Tilted Parallelogram Used for processes that involve some sort of input or output. Diamont Decision block. How to Compressed Project? Analysis of how quickly the project can be complete without respect to cost. In other words, crashing the project optimizes the time parameter of the project at the expense of resource utilization. Components and Events to Model Reneging Components This is when an entity enters the line but leaves before being processed. Simulation model components is a component that is meant to be used as part of a simulation model Jockeying representing a sub-system with a predefined reduction and generalization. Associated with parallel queues. This is when an entity switches between two different queues. Some common system components to be modeled: Personnel Data to be Included in the Model Machines Transporters Input Data Conveyors Input Data Collection Principles A fundamental concept where it break down Processes and Events the types of data into as many different independent types as possible. Process – series of steps and decision in the way work is completed. Types of Input Data Event – an important happening especially one that out Related to the concept of system entities which of and is connected with previous happenings. are the elements that are processed by the system. Parallel Queues – found in systems that have multiple System resources that are the parts of the resources. system that process the system entities. Single Snake Queue – often used to model complex Interarrival Times systems. These are the amount of time that passes between the arrivals of batches or groups of entities into Queue Priority the system. Order of the entities in the queue. Batch Sizes FIFO Number of individual entities that arrive at the LIFO same time to be processed by a system. Shortest Processing Time (SPT) Queue Entity Behavior Longest Processing Time (LPT) Lowest Value First (LVF) Balking, Reneging, Jockeying Highest Value First (HVF) Classifications User-defined Rules Types or priorities of entities arriving in the system. Queue Entity Behavior Service Times Actions of the entities with respect to entering Include processing times that a job or and remaining in the system queues. customer undergoes. Balking Failure Rates Occurs when a customer enters the system but Involve the frequency of process failure or leaves before entering a queue. Balking is the result of resource unavailability. facing a long queue wait or limited queue capacity. Scheduled Maintenance Direct Observation Involves reducing the availability of resources Physically and mentally demanding form of such as machines to perform preventive maintenance to data collection. reduce the probability of equipment failures. Break Times Collecting Input Data Primarily pertain to system resources such as operators and clerks. Data Collection Devices Time Collection Mode and Units Movement Times Include the duration for an entity to travel between areas of a system. Classifications of Data Probabilistic vs Deterministic Discrete vs Continuous Input Data Considerations Make note of what input data collection compromises were necessary. These compromises Input Data Distributions should be clearly documented under the assumptions Bernoulli Distribution and limitations section of the project report. This is used to model a random occurrence with one of two possible outcomes. These are frequently Lesson 5: Input Data Collection and Analysis referred to as a success or failure. Source Data Uniform Distribution Historical Records A uniform distribution means that over the range of possible values, each individual value is equally If a system has been in existence for some time, likely to be observed. it is likely that some form of historical records are available. This approach may appear to be a very Exponential Distribution attractive option to the practitioner. Commonly utilized in conjunction with Manufacturer’s Specifications interarrival processes in simulation models because the arrival of entities in many system has been either proven Most manufacturers will be providing a or assumed to be a random or Poisson process. theoretically based specification for their equipment. Normal Distribution Vendor Claims Processes where it consists of a number of This claim will fall between the manufacturer’s subprocesses. specification and reality. Triangular Distribution Operator Estimates Used in situations where the practitioner does If the operator is knowledgeable about the not have complete knowledge of the system but system, it may be possible to obtain some performance suspects that the data are not uniformly distributed. estimates that can be used as input data. Beta Distribution Management Estimates Distinction of being able to cover the range Soliciting managers or engineers associated between 0 and 1. with the system. Gamma Distribution Automatic Data Capture This can be somewhat intimidating. Electronic access to automate data. Weibull Distribution Often used to represent distributions that cannot have values less than zero. Analyzing Input Data Graphic Approach This approach consists of a visual qualitative comparison between the actual data distribution and theoretical distribution. Chi-Square Test Commonly accepted as the preferred goodness of fit technique. Based on the comparison of actual number of observations versus the expected number of observations. Kolmogorov-Smirnov Test KS Test should only be utilized when the number of data points is extremely limited and the chi- square test cannot be properly applied. Square Error The square error approach uses a summed total of the square of the error between the observed and the theoretical distributions.