International Data SIM / International Data Plan – Keepgo Review

I frequently travel internationally either as part of my job or for personal reasons. While I’m on the road, especially when traveling job related, it is very important for me to stay connected. A while ago I came across the Keepgo lifetime data SIM card.


What distinguishes Keepgo from other travel SIM cards is that it works in a lot of countries around the globe and that the data plan is valid a whole year. This means, for example, that I can use the international data plan while I’m in the taxi in Switzerland, when waiting for a connection flight in London and at my final destination in Shanghai.

There are two options to choice from to get started a 1 GB international data SIM only offer for $59 and a GB international data SIM + mobile WIFI hotspot offer for $119.

I tested the service in China, Switzerland, United Kingdom, Germany and in Spain and it worked very well.

If you use this link you get 15% off on your Keepgo lifetime data SIM card.

Automotive System Safety Europe

bildschirmfoto-2016-11-19-um-13-50-13 I will be speaking at the Automotive System Safety Europe conference in Berlin at November 29th, 2016. In my talk I will give some insides about how freedom from interference can be achieved in automotive systems. I will also discuss best practices on how to deal with mixed ASIL architectures and how freedom from interference can be achieved in legacy systems.

Personal Update

It has been a while since the last time I posted a blog post here. The reasons have been manyfold and include becoming a father for the first time, starting a job in industry while finishing up my PhD thesis and moving to a new house and all that at almost the exact same time 😉

All these milestones in my life obviously  shifted some the priorities in my life. This does not mean that the blog is no longer important for me, but I needed some time to decide in which direction I would like to go with this blog. After some time I know decided what I want this blog to be. I want it to be a reflection of my thoughts and ideas both professional and personal. This means that in the future I will write about

  • topics evolving around (automotive) software engineering, project management as well as functional safety
  • but also web development and technology in general and hobby-projects (e.g. home automation)
  • and I will write about my life as a dad

In terms of language I have not entirely decided whether all my blog posts will be in English or whether maybe the more personal ones will be in German.

I’m also not yet sure in which frequency I will be able to write blog posts but initially I will aim at one post per month … so keep tuned 😉

Functional Safety Book recommendation: Design and Safety Assessment of Critical Systems

I have updated my list of literature on functional safety with the book of Marco Bozzano et al..
The book is a very well written introduction into the topic of safety assessment and functional safety and I can recommend it for readers on beginner levels as well as for functional safety experts that want learn more about formal methods and model checking in the context of safety assements.

Design and Safety Assessment of Critical Systems (recommended)

by Marco Bozzano and Adolfo Villafiorita

Short Description (source:
Safety-critical systems, by definition those systems whose failure can cause catastrophic results for people, the environment, and the economy, are becoming increasingly complex both in their functionality and their interactions with the environment. Unfortunately, safety assessments are still largely done manually, a time-consuming and error-prone process. The growing complexity of these systems requires an increase in the skill and efficacy of safety engineers and encourages the adoption of formal and standardized techniques. An introduction to the area of design and verification of safety-critical systems, Design and Safety Assessment of Critical Systems focuses on safety assessment using formal methods. Beginning with an introduction to the fundamental concepts of safety and reliability, it illustrates the pivotal issues of design, development, and safety assessment of critical systems. The core of the book covers traditional notations, techniques, and procedures, including Fault Tree Analysis, FMECA, HAZOP, and Event Tree Analysis, and explains in detail how formal methods can be used to realize such procedures. It looks at the development process of safety-critical systems, and highlights influential management and organizational aspects. Finally, it describes verification and validation techniques and new trends in formal methods for safety and concludes with some widely adopted standards for the certification of safety-critical systems. Providing an in-depth and hands-on view of the application of formal techniques to advanced and critical safety assessments in a variety of industrial sectors, such as transportation, avionics and aerospace, and nuclear power, Design and Safety Assessment of Critical Systems allows anyone with a basic background in mathematics or computer science to move confidently into this advanced arena of safety assessment.

AVM 2013 Talk: Recent Advances in Causality Checking

On Tuesday May 28th 2013 I gave a talk at the Alpine Verification Meeting in Trento Italy with the title “Recent Advances in Causality Checking”. 

Abstract: In recent work on the safety analysis of systems we have shown how causal relationships amongst events can be algorithmically inferred from probabilistic counterexamples and subsequently be mapped to fault trees. The resulting fault trees were significantly smaller and hence easier to understand than the corresponding probabilistic counterexample, but still contain all information needed to discern the causes for the occurrence of a hazard. More recently we have developed an approach called Causality Checking which is integrated into the state-space exploration algorithms used for qualitative model checking and which is capable of computing causality relationships on-the-fly. The causality checking approach outperforms the probabilistic causality computation in terms of run-time and memory consumption, but can not provide a probabilistic measure. In my talk I will give an introduction to causality checking and probabilistic causality computation. Furthermore I will discuss how the strengths of both approaches can be combined to an approach where the causal events are computed using causality checking and the probability computation can be limited to the causal events.

The slides of my talk can be downloaded here.

Causality Checking at Microsoft Research

Stefan Leue, my PhD supervisor, recently visited Microsoft Research in Redmond and gave a lecture on the Causality Checking method we currently develop. Causality Checking will make up a large part of my PhD thesis.

video of the lecture is available online here.

Here is the abstract of his talk:

I will introduce Causality Checking, a technique extending model checking designed to establish causalities for safety property violations in system models. Causality Checking is based on counterfactual reasoning. In particular, it is based on an adoption of the Halpern/Pearl Structural Equation Model (SEM) for establishing actual causes. Causality Checking takes advantage of the fact that using a model checker it is fairly easy to compute both “bad” as well as alternate “good” worlds, where a world corresponds to a finite execution sequence.

Based on our adoption of the SEM I will show how causalities can be determined by performing difference computations on the sets of bad and good executions of a model. I will present two approaches how to perform this computation: one based on an explicit enumeration of all bad and good execution traces of a model, and another one based on an on-the-fly algorithm integrated into standard state space search algorithms used in explicit state model checking. I will sketch applications of Causality Checking to systems analysis by considering a number of case studies, including functional and probabilistic models. I will illustrate how the computed causalities can be displayed as fault trees and serve as a basis for system debugging.


Google Scholar Author Profiles

I just discovered a great new (?) feature of Google Scholar called author profiles.

There a two great benefits:

  • You can “follow”  authors and automatically get an email alert whenever they have published a paper, in my opinion a great way to keep track of what is going on in your research field.
  • You can “follow” citations of authors and for instance automatically get an email alert when somebody cites your paper.

A minor but still interesting point is that you can create a public or private author profile where

  • all your publications are listed,
  • metrics like citation count, h-index, i10-index and so on are computed,
  • and you can enter a link to your current website.

My public Google Scholar Author Profile can be found here. 

Tool List

Yesterday I received my new quad core PC and I want to present a list of software tools that I don’t want to miss:

Going Quad

On tuesday I orderd my new PC (or at least the components to build one ;))Here are the highlights: 

  • CPU: Intel® Core 2 Quad Q6600
  • Power Supply: be quiet! Straight Power BQT E6-400W
  • Mainboard: Asrock G41M-LE
  • HDD: Western Digital WD10EADS 1 TB
  • RAM: 2 X Kingston ValueRAM DIMM 2 GB DDR2-800 (will be updated to 8 GB later)