Business Process Simulation Marc Voorhoeve HG 7.86(247)2420

Course structure

Aim of the course: Obtain knowledge and skills w.r.t. business process simulation - whether or not to use simulation - how to conduct a simulation project - how to interpret its results

Course ingredients: - theory (lecture notes / slides) - exercises (class / home) - graded assignments (alleviates exam) - written exam (open book)

Course website: // - examples - exercises / assignments Arena download: //campusmp/software/rockwell downgraded version sufficient for course examples (not for real simulation projects)

Prerequisites: Modeling with Petri nets - 2V060 Systems modeling (Inf, old) - 2II05 Business information systems (Inf, new) - 1BB30 Process modeling (TM) Probability theory and statistics - 2DI25 (Inf) - 2DD13 (TM) Awareness of business processes - 1CC22 (TM) - common sense

Course subjects: - Appropriate use of simulation - Simulation study outline - Modeling - Methodology - Pitfalls

Role of Simulation

Strategic decisions: - infrastructure - control Operation characteristics - throughput - cost -... influence feedback change Business process Market trends: - quality - quantity influence

Trial-and-error approach very wasteful. Before making an investment, assess its effects (to the extent possible). Analysis: (probabalistic) calculations Both depend on parameters, obtained from historical data, added observations + extrapolations. Simulation: random generation of cases + measurement Strategy adaptation

Analysis: - common sense, - stochastic (markov), - queuing theory History Observations Extrapolation (use with care) Simulation validate results validate asssumptions Analysis vs. simulation

Simulation project life cycle Performance indicators of business Challenges, improvement alternatives Simple analysis, simulation yes/no? Essential features of business and proposed solutions conceptual / executable / parameters Problem definition Modeling Validation Experiment Interpret Replay history Assessment by stakeholders Simulate alternatives parameter sensitivity Write report Asess confidence

Examples

Passport A civil servant creates documents for citizens, who queue for his help. A photo must be attached to the document, which is judged by the servant. If the photo is judged inadequate, the citizen is deferred to a nearby photographer to make a new one. When the citizen returns with this photo, he gets priority (without judgement) and his document is made.

Ferry A ferry carries cars across a river. At each bank, cars can appear needing to cross. When the ferry is at a bank and is empty, cars can get on it. There are 10 places for cars at the ferry. If the ferry is full or if all cars at the current bank are on board, the ferry crosses to the other bank, where the cars get off. The cars waiting at the other bank can then enter the ferry, starting a new cycle. The current ferry needs replacement; it is at the end of its life cycle, there are complaints about long waiting times and traffic is expected to increase. The replacement candidates are a (faster) one with a capacity of 10 places and a (slower) one with a capacity of 15 places. Find out for both candidate replacements what the average waiting and throughput times of cars are for the present situation and when traffic increases by 10%.

DCT container terminal

keeper truck direction Container Terminal The Dutch Container Terminal (DCT) is situated in a port. Ships dock at the terminal, loading and unloading containers. The containers are temporarily stored in areas at the DCT premises and moved to and from the shippers by trucks. Any truck visiting DCT wishes either to fetch some container (an empty container or a specific filled container), to bring a container (empty or filled), or both. The numbers of B and F trucks are equal in the long run, but F trucks occur more frequently in the morning and B trucks in the afternoon. storage areas

Containers are moved off and on trucks by a crane. Before, the driver presents his papers to the keeper for checking and calculating commands for the crane. When a truck arrives, it first queues at the keeper’s desk. If the papers are approved, the truck queues for the crane. If not, the truck is set aside and the driver may try to set the papers right through telephone and fax. If this succeeds, the crane queue is entered and otherwise the truck returns without being serviced. Trucks in the crane queue wait their turn; then the container either is taken from a B truck and moved to a storage area or fetched from the storage area and put on an F truck or the container is taken from a BF truck and stored, after which a stored container is put on it.

Business is increasing. As a consequence, during busy hours, long truck queues may appear. DCT is prepared to invest money to improve matters. A consultancy team of which you are a member is hired to make suggestions for improvement. Is simulation an option?

Homework: Study chapters 1,2 of the lecture notes. Download Arena. Do the exercises on pages 6 and 10 Classwork / Homework Classwork: Study DCT case. Prepare (in groups) a list of questions pertaining to the case, discuss with stakeholder(s) obtain and document answers