1) Starlink Internet Access Link:

SpaceX Starlink, a Low Earth orbit (LEO) satellite megaconstellation, is interesting for users who do not have access to terrestrial Broadband Internet access. Compared to geostationary satellites, the latency of LEO satellites as significantly lower (round trip times: GEO ~600ms, LEO ~50ms), which is beneficial for many Internet applications and protocols.

Measurements with a Starlink terminal have shown that both data rate and latency is very unstable given the currently deployed system. Both data rate and latency show significant fluctuations. For testing applications and protocols in a network simulation environment, it is important to have a model of such link characteristics. In this project, a model of an Starlink Internet access link shall be created. This should include data rate and latency, as shown above. Optionally, packet loss and latency under load could be measured and modeled (c.f., Bufferbloat).

2) HTTP web traffic model:

Modern web pages are very diverse: Some have only a few objects and are optimized for fast loading, while others are very complex. See following two figures for illustration. It is not possible to define a typical website. Therefore, simplified models are desirable. The basis for this project topic are the publications [1] and [2]. They measure page size, number of objects, and object sizes for a large number of web pages and provide corresponding models. As websites have significantly changed since 2012, the results from [1] are outdated. A more recent model of website parameters is given in [2] but lacks some aspects which should be considered when analyzing modern websites: HTTP version, number of contacted servers, mobile vs. desktop websites, impact of cookie banners, etc. Also, the data set used for evaluation should be made available publicly.

3) Hydrogen energy storage for communal E-Vehicle charging:

The transition to a CO2 neutral energy system is one of the most challenging endeavours of this decade. Even though there are several potential technical solutions, there are still many open questions. Especially regarding energy storage and management in a decentralized system.

A promissing solution for storing energy in the usage of hydrogen (H2). Most commonly used are electrolysers to convert water to H2, which can be burned to retrieve the stored energy using turbines. The goal of this project is to evaluate the useage of H2-Energy storage for a communal charging service for 20 to 50 electric vehicles. The town wants to use wind power plants with a height of 100 to 140 meters. The charging service shall mainly be used as a park and ride solution. Suitable models for energy production, storage, retrieval and user behavior and useage patterns have to be developed. Optional questions revolve around the interface to the general energy grid and the energy market. For example: How much energy has to be bought in addition? How much can be sold? How could a price dependent control strategy look like and what is the impact on costs and quality of service?

4) Thermal energy storage for residential buildings:

The transition to a CO2 neutral energy system is one of the most challenging endeavours of this decade. Even though there are several potential technical solutions, there are still many open questions. Especially regarding energy storage and management in a decentralized system.
In residental buildings around 80% of the total energy is used for heating. A common technology for heating is the use of thermal energy storage, i.e. heating water in an thermally insulated tank. This heat can also be used to retrieve the energy and generate electricity. The goal of this project is to evaluate the useage of thermal energy storage for a residential building. The theoretical building has an area of 80 to 160m² and a roof surface of 50m² that is usable for photovoltaic solar panels or thermal solar panels. In addition the stored and generated energy shall be sufficient to charge one electric car over night.
Optional questions revolve around the interface to the general energy grid and the energy market. For example: How much energy has to be bought in addition? How much can be sold? How could a price dependent control strategy look like and what is the impact on costs and quality of service?

Title:

Exercises to: Simulation and Modeling II

Credits: 5

Prerequisites

Prior participation in the course "Simulation and Modeling 1" is strongly recommended.

Contents

The participants conduct a simulation project over the whole semester in groups of 3 to 4. The participants may submit project proposals or work on one of the following projects:

1) Exit Strategies from COVID-19 Lockdown: Based on the paper "Modeling Exit Strategies from COVID-19 lockdown with a Focus on Antibody Test", the already existing system dynamics model can be extended or an own agent-based model can be developed. The simulations could focus on the effects of the "Contact-Tracing Apps", different age groups, or the influence of vaccinations. Further considerations and ideas are welcome. The corresponding paper is available on the chair website. The paper presents two epidemiological models that have been developed in order to study the disease dynamics of the COVID-19 pandemic and exit strategies from the lockdown which has been imposed on many countries world-wide. A strategy is needed such that both the health system is not overloaded letting people die in an uncontrolled way and also such that the majority of people can get back their social contacts as soon as possible. We investigate the potential effects of a combination of measures such as continuation of hygienic constraints after leaving lockdown, isolation of infectious persons, repeated and adaptive short-term contact reductions and also large-scale use of antibody tests in order to know who can be assumed to be immune and participate at public life without constraints. We apply two commonly used modeling approaches: extended SEIR models formulated both as System Dynamics and Agent-Based Simulation, in order to get insight into the disease dynamics of a complete country like Germany and also into more detailed behavior of smaller regions. We confirm the findings of other models that without intervention the consequences of the pandemic can be catastrophic and we extend such findings with effective strategies to overcome the challenge. Based on the modeling assumptions it can be expected that repeated short-term contact reductions will be necessary in the next years to avoid overload of the health system and that on the other side herd immunity can be achieved and antibody tests are an effective way to mitigate the contact reductions for many.

2) Railway Network Simulation: With the developing technologies and methods in the field of real-time communication and the constantly increasing amount of data to be transmitted, the railway industry has jumped on the bandwagon of modernizing its processes. The aim is to merge the separate networks for train control and non-critical information, e.g. for passenger information, and also to be compatible with other train manufacturers. In the field of real-time communication, Time-Sensitive Networking (TSN) has emerged as a possible solution to overcome the above-mentioned challenges. It provides procedures and mechanisms for Ethernet technology, enriching it with aspects of determinism and reliability. TSN enables the sharing of real-time and best-effort traffic on a single line. As there are only a few TSN-enabled devices on the market so far, the validation of TSN technology is limited. Simulation offers a good alternative in this situation. The tool OMNeT++ is a modular, C++ based framework for network simulation. A suitable TSN library already exists for this purpose, which covers the most important mechanisms for real-time communication. Within the project, a next-generation train network with TSN mechanisms will be built and the necessary cyclic TSN messages, like brake signals, and acyclic or stochastic messages like passenger information will be defined. Finally, the simulation shall be evaluated. Thereby, the focus will be on maintaining real-time capability and the use of bandwidth. All mechanisms and information are already given for the setup of the simulation. An introduction to TSN will be given.

3) High Level Sensor Models: The development and testing of automated driving functions in the real world is costly and time-consuming. For this reason, software for automated driving is at first developed and tested in a virtual environment. The provision of the virtual environment requires the coupling of several simulation tools and models. An essential feature of the simulation setup are the sensor models. A distinction is made between low-level models and high-level models. Low-level models replicate physical effects, e.g. through ray tracing. They are highly precise, but they require a lot of computing power. High-level models filter an object list based on geometric constraints. They are less accurate, but faster than the low-level sensor models. The aim of the project is the design and implementation of a high level sensor model. The sensor model receives as input a list of all objects available in the virtual world of the submicroscopic traffic simulator "Carla". As output, the sensor model provides all objects in the visibility range of the ego-vehicle. The programming is carried out in Python, for which "Carla" offers an API.