On the correctness of upper layers of automotive systems

Formal verification of software systems is a challenge that is particularly important in the area of safety-critical automotive systems. Here, approaches like direct code verification are far too complicated, unless the verification is restricted to small textbook examples. Furthermore, the verification of application logic is of limited use in industrial context, unless the underlying operating system and the hardware are verified, too. This paper introduces a generic model stack, allowing the verification of all system layers as well as the concrete application models being used in the upper layers. The presented models and proofs close the gap between the correctness proof for the lower layers of car electronics developed at the Saarland University and the verification procedure for distributed applications developed at the Technische Universität München.     

Horn equational theories and paramodulation

A language of equational programs together with an inference system, based on paramodulation is defined. The semantics of the language is given with respect to least models, least fixpoints and success sets and its soundness and completeness is proven using fixpoint theory. The necessity of the functional reflexive axioms is investigated in detail. Finally, the application of these ideas to term rewriting systems is outlined by discussing directed paramodulation and narrowing.     

Metrological traceability chain for pH measurement results

The extent to which technical barriers to international trade caused by non-acceptance of chemical measurement results can be removed, largely depends on the success in building up national and international traceability structures also in metrology in chemistry. Achieving metrological comparability of measurement results requires the definition of metrological calibration hierarchies providing metrological traceability chains which enable the establishment of metrological traceability of measured quantity values to a common metrological reference [1]. For pH, over the last decade, work has been carried out in a number of countries to build up meteorological calibration hierarchies within a national framework. An overview on the metrological traceability chain for pH is given with focus on the primary measurement procedure of pH.     

Volume change and gas transport at uniaxial deformation of filled natural rubber

The volume dilatation of differently filled specimens of natural rubber has been measured using a deformation dilatometer. If the matrix detaches from the filler particles, hollow spaces form. The volume dilatation caused by this effect can be measured and calculated if the material is submerged in a liquid medium. The measured volume dilatation reflects the interaction between filler and matrix. If we take a measurement in a gas, only the volume dilatation of the matrix is recorded, but not that of the visible hollow spaces, because gas can diffuse from the measurement chamber into the sample. Stress-induced crystallization occurs with all samples. Its course due to deformation has been examined using a deformation calorimeter. Here an influence of the interaction between filler and matrix has been found. Filler particles which do not adhere closely to the matrix enhance the diminution of locally high tensions and deformations and thus hinder the stress-induced crystallization. The volume contraction caused by stress-induced crystallization can be recorded clearly only if one uses a liquid as the measurement medium. Due to gas exchange between the sample and its environment and the different gas solubilities in the amorphous and crystalline material no stress-induced crystallization can be detected. At the same time, a possibility opens up of determining gas solubilities in crystalline material.[/p]Dedicated to Professor Dr F. H. Müller on the occasion of his 80th birthday.     

Influence of processing parameters on quality factors of one-shot hybrid structures made by RTM

This paper is dealing with the influence of processing parameters for manufacturing of steel–carbon-fiber-reinforced-plastic (CFRP) hybrid plates by using the one-shot-hybrid resin-transfer-moulding (OSH-RTM) process. A design of experiments study was carried out. The quality of the manufactured parts was quantified by the bending modulus, the apparent interlaminar shear strength (ILSS), the maximum deflection and the density of the CFRP. The following changeable processing parameters were chosen: mould temperature, resin temperature, change in mass flow and maximum injection pressure. It is shown that the mould temperature and the change in mass flow show significant impact on the flexural modulus, density and maximum deflection of the plate while there is no significant impact on the apparent ILSS. Furthermore, the interaction between the mould temperature and resin temperature is having an influence on the flexural modulus and density.