A Tool to Optimize the Initial Distribution of Hydrogen Filling Stations

An important barrier towards the introduction of fuel cell vehicles (FCVs) running on hydrogen is the lack of widespread refueling infrastructure. The niche of buses for public transport, taxis and deliverers with a local application area might not be large enough to generate the reductions of FCV costs that are necessary for a general technology switch. Thus, fuel availability at trunk roads probably plays a crucial role in generating demand for FCVs also from private consumers. In this paper we assume that consumers are more likely to consider buying a FCV the more frequently they are exposed to hydrogen refueling opportunities on long distant trips. We introduce a tool to test different small scale initial distributions of hydrogen outlets within the German trunk road system for their potential success to generate a large scale adoption of FCVs. The tool makes use of agent based trip modeling and Geographic Information System (GIS) supported spatial modeling. We demonstrate its potentials by testing a ring shaped distribution of hydrogen outlets at highway filling stations. We find that the structure of an optimized initial distribution of filling stations depends on what drivers consider a sufficiently small distance between refueling opportunities.Agent based modeling, Alternative fueled vehicles, Hydrogen, Fuel Cells

Optimal CO2-abatement with socio-economic inertia and induced technological change

The impact of induced technological change (ITC) in energy/climate models on the timing of optimal CO2-abatement depends on whether R&D or learning-by-doing (LBD) is the driving force. Bottom-up energy system models employing LBD suggest strong increases in optimal early abatement. In this paper we extend an existing top-down model supporting this view according to the notion that socio-economic inertia interferes with rapid technological change. We derive analytical results concerning the impact of inertia and ITC on optimal initial abatement and show a wide range of numerical simulations to illustrate magnitudes. Inertia now dominates the timing decision on early abatement, such that LBD might even have a negative effect on early abatement and the impact of R&D is limited. However, ITC still reduces costs of stabilizing atmospheric CO2-concentrations considerably.climate policy; technological change; inertia

An Improved Construction of Petri Net Unfoldings

Petri nets are a well-known model language for concurrent systems. The unfolding of a Petri net is an acyclic net bisimilar to the original one. Because it is acyclic, it admits simpler decision problems though it is in general larger than the net. In this paper, we revisit the problem of efficiently constructing an unfolding. We propose a new method that avoids computing the concurrency relation and therefore uses less memory than some other methods but still represents a good time-space tradeoff. We implemented the approach and report on experiments

Concrete admixtures - sustainable concrete

Durability of concrete, an important part of the sustainability theme, was, is, and will be one of the main topics for large infrastructure projects like the Gotthard base tunnel. For such important structures a service life of more than 80 years is expected. The prevailing underground conditions like water ingress, aggressive waters etc. will influence the choice of the concrete system and mix design. Therefore, a focus is on the potential damage mechanisms on the concrete like chloride ingress or sulfate attack. A well-designed concrete will be durable concrete which can withstand various external attacks and achieves or even extends the designed service life of the concrete structure. Based on the knowledge that the main damaging mechanisms for concrete are based on water penetration into the concrete, various measures can be taken to achieve concrete structures with significantly reduced permeability. These measure ranges from reduction of the water/binder-ratio, increasing the density of the concrete using silica fume, to the use of special admixtures in order to increase the durability of concrete. In an extensive research program, the influence of mix design components e.g. different admixture types, water/binder-ratio on hardened concrete properties like chloride resistance (chloride migration coefficient), sulfate resistance and water conductivity have been tested and analyzed

A complex systems methodology to transition management

There is a general sense of urgency that major technological transitions are required for sustainable development. Such transitions are best perceived as involving multiple transition steps along a transition path. Due to the path dependent and irreversible nature of innovation in complex technologies, an initial transition step along some preferred path may cut off paths that later may turn out to be more desirable. For these reasons, initial transition steps should allow for future flexibility, where we define flexibility as robustness regarding changing evidence and changing preferences. We propose a technology assessment methodology that identifies the flexibility of initial transition steps in complex technologies. We illustrate our methodology by an empirical application to 2646 possible future car systems.NK-model, complexity, flexibility, irreversibility, path dependence, transition path, transition management, sustainable development, car technology

Flexible transition strategies towards future well-to-wheel chains: an evolutionary modelling approach

Well to wheel (WTW) analyses mainly focus on alternative road fuel/vehicle systems that are very different from the current crude oil based individual transport system. A large share of WTW chains evaluated require changes in the energy source, new fuel production facilities, different fuel distribution systems and also modifications of the vehicles. An immediate transition to such a new system would be an unprecedented technological discontinuity. Historical examples of successful technological changes are characterized by stepwise transitions of subsystems. In this paper, we present a model that identifies likely sequences of stepwise transitions in analogy to the fitness landscape model in evolutionary biology. Applying this methodology allows for a dynamic interpretation of otherwise static WTW information. We show that sequences of transitions are path dependent, so that current decisions predetermine the future WTW system. We, therefore, argue that flexible initial transition steps that allow for different transition paths later on are favorable. Results suggest that improvements of vehicle technologies are most flexible if decision makers focus on decreasing WTW energy requirements. A full transition to diesel, as a first step, is advisable if WTW greenhouse gases should be reduced.Alternative fuels, Hydrogen, Lock-in, Fitness-landscape

Exact Gap Computation for Code Coverage Metrics in ISO-C

Test generation and test data selection are difficult tasks for model based testing. Tests for a program can be meld to a test suite. A lot of research is done to quantify the quality and improve a test suite. Code coverage metrics estimate the quality of a test suite. This quality is fine, if the code coverage value is high or 100%. Unfortunately it might be impossible to achieve 100% code coverage because of dead code for example. There is a gap between the feasible and theoretical maximal possible code coverage value. Our review of the research indicates, none of current research is concerned with exact gap computation. This paper presents a framework to compute such gaps exactly in an ISO-C compatible semantic and similar languages. We describe an efficient approximation of the gap in all the other cases. Thus, a tester can decide if more tests might be able or necessary to achieve better coverage.Comment: In Proceedings MBT 2012, arXiv:1202.582