Simulation der Elektrolytströmung in einer Kupfer Raffinationselektrolysezelle

A computational fluid dynamic simulation of the electrolyte flow in a full-scale copper electrorefining tankhouse cell has been performed. The electrolyte flow is effected by small scale events caused by concentration gradients very close to the electrode surfaces as well as by large scale events caused by the circulation of a fresh electrolyte. The electrolyte flow patterns in the tankhouse cell have been successfully modelled by using a hybrid global and local simulation approach. To verify the simulation model, a set of tracer experiments has been performed on an industrial tankhouse cell, and a very good agreement between the model and the experiments has been found.     

The Role of Network Topology and the Spatial Distribution and Structure of Knowledge in Regional Innovation Policy: A Calibrated Agent-Based Model Study

Recently, new regional innovation policy paradigms emerged that transcend a long-lived dispute on whether either regional specialization, diversification, or rather related variety is most conducive to regional innovativeness. This includes ‘smart specialization’ in which regions are deliberately specialized and connected following technological relatedness, ‘gatekeepers’ in which there are pipelines between dense regional networks, and a ‘regional mix’ of knowledge that allows sustained ‘branching’. We develop and use an agent-based model to study the conjecture that, to stimulate (supra)regional innovativeness, social planners need to consider both, in conjunction, the mix of technological knowledge in regions and the (inter)regional innovation network topology. We use this agent-based model to evaluate the performance of and study the internal mechanisms of these new policy paradigms in a variety of scenarios. To increase the external validity of our findings, we calibrate the knowledge graph searched by the agents in our model to the OECD patent database. We confirm that access to related variety is important, yet that, on top of that, access to incidentally related knowledge is crucial to prevent high-level lock-in and ensure long term technological progress. Moreover, we find that networks with regional gatekeepers are particularly innovative, because these gatekeepers form ‘knowledge hubs’, create short paths to potential partners, and enlarge the total pool of knowledge. In case agents have few relationships, we find exceptionally high performance for the gatekeeper network in combination with regional diversification. The smart specialization network is a solid second option, although it lacks access to incidentally related knowledge and thus will ultimately fall behind whenever agents have relatively few relationships. The study elaborates on specific scenarios to reveal intricacies in the relationship between knowledge distribution, network topology, and the structure of interrelationships between knowledge fields.     

Hole Expansion of Dual‐phase and Complex‐phase AHS Steels ‐ Effect of Edge Conditions

Hole expansion is one of the most important properties describing the formability of steel sheets, especially those used in automotive industry. In order to determine and emphasize the influence of hole edge conditions and hole surface quality on the results of standardized hole expansion tests, different hole preparation methods such as hole punching, hole drilling and wire cutting were applied to the industrially produced dual–phase and complex–phase steel grades DP800 and CP800. Results of hole expansion testing were discussed with respect to the impact of deformation introduced into the material during the hole preparation and to the material microstructure and mechanical properties. The damage characteristics of every method as well as the fracture surfaces were investigated in detail via light optical microscopy (LOM) as well as scanning electron microscopy (SEM). Qualitative and quantitative analyses of microstructure combined with microhardness measurements were used for the interpretation of the results and are correlated with the mechanical properties and the formability characteristics of the investigated steel grades.     

Efficient algorithms for checking the atomicity of a run of read and write operations

LetX ₁,...,X _c be variables shared by a number of processorsP ₁,...,P _q that operate in a totally asynchronous and wait-free manner. An operation by a processor is either a write to one of the variables or a read of the values ofall variables. Operations arenot assumed to be instantaneous and may arbitrarily overlap in time. A succession of possibly overlapping operationsa ₁,...,a _n (i.e., a run) is said to be atomic, if these operations can be serialized in a way compatible with any existing precedences among them and so that any read operation returns for each variable the value of the most recent — with respect to the serialization — write operation on this variable. This paper examines the complexity of the combinatorial problem of testing a run for atomicity. First, it is pointed out that when there is only one shared variable or when only one processor is allowed to write to each variable, known theorems lead to polynomial-time algorithms for checking the atomicity of a run (the variable of the time-complexity function is the number of operations in the run). It is then proved that checking atomicity has polynomial-time complexity in the general case of more than one variables and with all processors allowed to read and write each variable. For the proof, the atomicity problem is reduced to the problem of consecutive 1s in matrices. The reduction entails showing a combinatorial result that might be interesting on its own.The research of the first author was partially supported by the European Union ESPRIT Basic Research Projects ALCOM II (contract no. 7141) and Insight II (contract no. 6019).The research of the second author was carried out while he was a student at the University of Patras and also during subsequent visits of his to Patras.