Grundlagen für die rechnergestützte Aufstellungsplanung

Principles of Computer-Aided Assembly Planning . The assembly planning for a chemical engineering plant defines the position of the individual machines and articles of equipment in an appropriate grid (Fig. 1). Apart from the demands of pipe routing, numerous widely differing, partly contradictory, boundary conditions influence the assembly of a plant. These include, among other factors, investment and assembly costs, ease of maintenance and operation, as well as safety and environmental protection. Thus numerous specialist areas are involved in this planning work, with the definition of the ?optimum”? solution being based on individual studies and particularly on experience.     

Bioactive Titanium Surfaces Enriched with Silver Nanoparticles Through an In Situ Reduction: Looking for a Balance Between Cytocompatibility and Antibacterial Activity

This research aims toward an antibacterial and osteoconductive Ti₆Al₄V surface by chemical etching–oxidation treatment and in situ reduction of silver nanoparticles. Starting from a previously developed process, already proved to enhance the osteoinductive ability of titanium, different parameters are changed to tailor the amount of silver and its distribution across the surface oxide layer thickness. The samples are characterized by scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, release of silver, biofilm formation (Staphylococcus aureus), and cytocompatibility toward human osteoblasts progenitor cells. The total amount of silver in the surface oxide layer depends only on the concentration of the silver precursor. The time of the addition of the silver precursor, during the oxidation treatment, affects the oxide layer thickness, dimension, and distribution of the nanoparticles across the surface oxide: they are larger and accumulate on the outermost layer, if the addition occurs early. The maximum ion release occurs after 24 h and lasts up to 14 days; the later addition of silver precursors leads to sustaining the silver release for a longer time. The samples prepared with the higher concentration of the silver precursor are bactericide, but highly cytotoxic, whereas the other ones are bacteriostatic and moderately cytotoxic.     

The effects of working height and manipulated weights on subjective strain, body posture and muscular activity of milking parlor operatives--laboratory study

The incidence of work-related musculoskeletal disorders among milking parlor operatives has increased while milking parlors were getting bigger. At the same time parlor design was improved regarding the physical load as well as body postures. In contrast to former studies on workload in parlor milking this project was designed and performed as an experimental study in a laboratory setting including 6 female subjects. Motion analysis and psycho-physiological analysis (EMG, heart rate, subjective perceived strain index) were carried out. Intra-individual comparisons were made for the different settings using general linear models for repeated measurements. The effects of working height and weight of milking unit during parlor milking were investigated regarding the impact on muscular load and body posture. The results showed that the optimal working height for attaching the cluster is having the teats at shoulder level of the parlor operative. Another important workload reduction was achieved by reducing the weight of the milking cluster. The named discomfort, localized fatigue and the body posture analysis provide evidence that the changes in modern milking parlors due to mechanization still bear the risk of overburden for the worker.     

Biomechanical evaluation of supermarket cashiers before and after a redesign of the checkout counter

An experiment was carried out on supermarket cashiers to evaluate the time, kinematic and electromyographic changes, in both sitting and standing positions, following the redesign of a checkout counter. The novelty of the prototype checkout counter is a disk wheel placed in the bagging area, which is designed to avoid the cashier having to manually push products along the bagging area. The kinematic evaluation was based on the upper limb and trunk range of motions (RoM). The electromyographic parameters assessed were mean and maximum muscular activations. Three factors were taken into account: design (before and after redesign), posture (standing or sitting) and bagging area (anterior or posterior). The results show that the RoM values are lowest after the intervention and in the standing position. Mean and maximum muscular activation patterns are similar. Differences related to the bagging area in which the goods were released also emerged. The disk wheel represents a valid aid for reducing biomechanical overload in cashiers; the standing position is biomechanically more advantageous. Practitioner Summary: EMG and optoelectronic motion analysis systems are useful for the quantitative assessment of the effects of the redesign of the workplace biomechanical risk. Our results suggest that a disk wheel positioned in the bagging area reduces the biomechanical risk for cashiers and increases time spent resting.     

MARVIN: a medical research application framework based on open source software

This paper describes the open source framework MARVIN for rapid application development in the field of biomedical and clinical research. MARVIN applications consist of modules that can be plugged together in order to provide the functionality required for a specific experimental scenario. Application modules work on a common patient database that is used to store and organize medical data as well as derived data. MARVIN provides a flexible input/output system with support for many file formats including DICOM, various 2D image formats and surface mesh data. Furthermore, it implements an advanced visualization system and interfaces to a wide range of 3D tracking hardware. Since it uses only highly portable libraries, MARVIN applications run on Unix/Linux, Mac OS X and Microsoft Windows.     

Which factors obstruct or stimulate teacher educators to use ICT innovatively?

This article discusses the factors which stimulate or limit the innovative use of ICT by teacher educators in the Netherlands. Innovative use of ICT is defined as the use of ICT applications that support the educational objectives based on the needs of the current knowledge society. Explorative path analysis and case studies were used to study the potential influencing factors. Results show that several factors on teacher level influence the implementation of innovative ICT-use in education. Especially, teachers who are so-called ‘personal entrepreneurs’ are important for the integration of ICT in teacher education. School level factors turn out to be of limited importance for innovative use of ICT. This indicates a limited involvement of the management of teacher training institutes towards the use of ICT within the curriculum.     

A solver for QBFs in negation normal form

Various problems in artificial intelligence can be solved by translating them into a quantified boolean formula (QBF) and evaluating the resulting encoding. In this approach, a QBF solver is used as a black box in a rapid implementation of a more general reasoning system. Most of the current solvers for QBFs require formulas in prenex conjunctive normal form as input, which makes a further translation necessary, since the encodings are usually not in a specific normal form. This additional step increases the number of variables in the formula or disrupts the formula’s structure. Moreover, the most important part of this transformation, prenexing, is not deterministic. In this paper, we focus on an alternative way to process QBFs without these drawbacks and describe a solver, $\ensuremath{\sf qpro}Various problems in artificial intelligence can be solved by translating them into a quantified boolean formula (QBF) and evaluating the resulting encoding. In this approach, a QBF solver is used as a black box in a rapid implementation of a more general reasoning system. Most of the current solvers for QBFs require formulas in prenex conjunctive normal form as input, which makes a further translation necessary, since the encodings are usually not in a specific normal form. This additional step increases the number of variables in the formula or disrupts the formula’s structure. Moreover, the most important part of this transformation, prenexing, is not deterministic. In this paper, we focus on an alternative way to process QBFs without these drawbacks and describe a solver, , which is able to handle arbitrary formulas. To this end, we extend algorithms for QBFs to the non-normal form case and compare with the leading normal form provers on several problems from the area of artificial intelligence. We prove properties of the algorithms generalized to non-clausal form by using a novel approach based on a sequent-style formulation of the calculus. This paper is based on an extended abstract presented at ECAI 2006 (see [16]). This work was supported by the Austrian Science Fund (FWF) under grant P18019, the Austrian Academic Exchange Service (?AD) under grant Amadée 2/2006, and by the Austrian Federal Ministry of Transport, Innovation and Technology BMVIT and the Austrian Research Promotion Agency FFG under grant FIT-IT-810806.