Selected Previous Projects

• Ambulance Station

The project is about simulating the rescue service system in the region of Nürnberg, Fürth and Erlangen. As far as the real world scenario is concerned there is one emergency dispatch center in Nürnberg performing emergency call service management. The corresponding ambulance vehicles are hosted in rescue service stations all over the region. Beside emergency services, as a provision for people with limited physical abilities the rescue service system is responsible for transporting persons from their homes to a physician and back respectively.
The major costs of a rescue service system arise from the amount of vehicles in expostulation, in particular these costs are due to personnel costs of the employees and maintenance costs of the vehicles. Accordingly the major goal of the project is to find the minimum number of vehicles necessary to accomplish the arising tasks. A decisive measure in this context is the so-called critical phase, which is the time period where all ambulance vehicles (so-called RTWs) and all patient transport vehicles (so-called KTWs) are in action so that another incoming emergency call cannot be handled until at least one of the vehicles returns. In this regard the duration of the critical phases has to be minimized with the smallest number of vehicles possible. Another aspect when determining the amount of vehicles necessary is the average utilization. In this context two measures are examined. The first one is the average number of vehicles in use. The second one is the percentage of time a vehicle is in action compared to the time it is not used.

• Bus Line

In this project, the bus line No. 289 in Erlangen from Büchenbach Nord to Waldkrankenhaus is considered. A bus line can be treated as a discrete-event system. For instance, the number of customers on the bus and the travel distances of customers are random variables. Moreover, interarrival times of customers at the bus stop are discrete events.
The simulated time is the rush hour, i.e., from 7:00 am to 9:00 am. Although it is possible to simulate the whole day’s operation of the bus line, one of the purposes of this project is to optimize the configuration of the bus line to avoid crowding, but usually crowding does not happen except for the rush hour. The motivation of this project is to model the bus line and obtain the relevant performance measures dependent on an input time schedule. During the rush hour, there are plenty of customers who want to get on the bus. On the one hand, if the time interval of two adjacent busses is too long, considering limited capacity of the bus, crowding will happen. On the other hand, if the time interval is too short, the number of busses will increase, which will generally increase the cost of the bus company. Therefore, an optimal scheme to configure the time schedule needs to be found.

• Drinks Terminal

Object of study is the so called Drinks Terminal (in German: Getränke Terminal), an automated retail trade shop for beverages. No service personnel is employed, customers cannot enter the business premises but place their orders at a terminal and are eventually served by crane robots, which also labour as warehousemen.
The objective of this work is to build an abstract model of the drinks terminal which should resemble as close as possible the behaviour of the real system. The model shall be used to simulate how the functional entities of the terminal – the crane robots and conveyor belts – work under certain conditions, like normal load (i.e. number of customers), heavy load and in the case of errors.
We assess the system according to the following performance measures: mean time customer spends in queue, mean time between finishing payment and leaving the terminal (which includes the interaction of cranes and conveyor belts to serve the customer), queue lengths averaged for both terminals, utilization of the cranes, customer throughput per hour.

• Supermarket

Today's cash desks in supermarkets are a common bottleneck in our everyday task to collect food in the urban domain. Being the one point where one has to interact with service personnel directly, cash counters usually kick customers out of their shopping flow by making them wait. A cashier waiting for new arrivals is most desirable for the just-finished-shopping customer, whereas most undesirable for the management, for he is someone being paid for doing nothing. So supermarkets (especially large ones) tend to save employment cost by reducing the number of working cash desks to an optimised minimum, which turns out to be a trade-off with customers’ patience. At every cash desk a queue is forming, growing and shrinking dependent on new customers arriving and served customers leaving the place. A supermarket in Erlangen has introduced a mechanism to cheer up waiting customers. The management imposes upon itself a penalty fee for every customer waiting for more than five minutes while not all cash desks are in service.
This simulation project investigates the system of waiting people at supermarket cash counters. The correlation between waiting queue length and the number of cash desks in service is the central aspect of this study. The simulation will produce measures to prove that the number of cash counters (servers) affects the mean queue length and waiting time of customers in the queues. The obligatory goal of this study is to inquire about how many cash counters are to be engaged in order to keep the mean waiting time/mean queue length below certain thresholds given a certain amount of traffic. The (simulation-based) computed correlation thus will answer the question, how the supermarket can avoid the penalty fee expenses.

• Street Cafe

In a so-called sidewalk café located in the city of Erlangen, you are able to spend your time at two different parts of the café – inside and outside of the building. We investigate the outside area of this café, where the usual services like ordering beverages and food are offered. The management employs some personnel for fulfilling the needs and wishes of the guests, consisting e.g. of waiters, cooks, etc. These employees have to shuttle between the outer area and back-end inside of the building, where the order processing takes place.
A study like this depends on the point of view, namely that of the guests or that of the management. Acting as a customer, it is important for him to spend a relaxing time at the café, not encountering problems with waiting for things like ordering, delivery or paying. On the other hand, the management tries to reach the maximum economical output by satisfying the guests needs in a proper way, combined with a reduction of the necessary resources and a high utilization of all system components.
Within the scope of this project, there will be an investigation of the exterior part of a restaurant/café in the peak time (11:30 am – 04:00 pm), taking place in the afternoon on sunny days. In the current configuration, there are four employees at the bar used to handle the beverage orders and three persons work in the background to prepare the food orders. In the service area two people directly take care the customers and two other employees are intended to deliver the orders and clean up the tables et cetera. The quantity of the tables varies between 35 and 50 depending on external factors like season and weather conditions. Currently you will find four chairs arranged around each table.
Using the simulation, we search for answers to the following questions: Which are the advantages/disadvantages of the usage of a radio system for receiving an order and transferring it to the bar for processing? Is it optimal to assign a fixed service area to the service personnel or not? How will changes in the number of tables, chairs per table, number of employees affect the system? Does it make sense to employ specialized personnel (cashier, waiter, …)? etc.
The considered system performance measures include the total customer time in system, time between arrival/order and delivery, café utilization, personnel utilization, throughput of customers for the whole system, throughput of service tasks for the service personnel, queue length of service tasks at the bar, etc.

• Intersection

People need to reach work places, shops, etc. Goods flow in and out from industries or commerce. These, among other factors, make the streets and roads full of vehicles, trucks or busses. At the same time, the time convention for working hours congest the traffic system at the rush hours. Facing this problem, the optimization of the traffic networks is not just desirable but also necessary.
This project does a simulation study of three intersections in the south of the city of Erlangen in the rush hour. The intersections modeled comprise 21 traffic lights, 22 source and 15 sink lanes. The simulation optimization goal was to minimize the total delay of cars in the intersection area by choosing improved traffic light schemes. We also study what-if questions by increasing the traffic load in the model (as may be expected for the future) and checking, if predefined thresholds on time in system, queue lengths, etc. can still be observed.

FlexRay Project Info

• Requirements Specification
• Protocol Specification
• Node-Local Bus Guardian Specification
• Central Bus Guardian Specification
• Electrical Physical Layer (EPL) Specification
• EPL Application Notes