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- quality control (3) (entfernen)
Control chart systems are used in quality management systems to keep production processes stable. In concrete production they are often applied for the control of the compressive strength. The most efficient control chart systems are cumulated sums (cusum), which help to observe deviations from a targeted value. Unlike alternative observation chart systems that focus on process data evaluation, cusum observations react very rapidly on systematic process changes in processes. Therefore, the cusum method is particularly suitable if immediate counteractions have to be taken, like in the case of fresh concrete properties of self-compacting concrete (SCC), which can have severe influences on the durability and mechanical strength of concrete. The rheology of SCC can be affected by an enormous variety of influencing factors, from raw material properties to handling or environmental temperature. The present study shows that regardless of the material based influencing parameter for a rheology change, a steady slump flow can be achieved only by adding supplementary superplasticizer in case of loss of flow and adding stabilising agent (ST) in case of increased flow if the respective V-mask indicates a systematic change. A reference SCC was artificially manipulated in order to achieve realistic experimental data for flowability and flowability changes due to changes in the raw material properties. The results point out that productions with applied cusum methods were capable of keeping the target slump flow deviation within approximately 1% only, while productions without applied cusum method deviated up to 14% and more from the target.
The BAM-Fallhammer is a mechanical device to test the impact sensitivity of explosives and to determine a sensitiveness level. By its construction it transforms potential energy into kinetic energy of an impacting hammer, then hitting the sample. Ideally the entire potential energy is available at the moment of impact and the supporting base is infinitely rigid. By this study we want to quantify how much a real Fallhammer deviates from the ideal concept, and what the differences between different Fallhammers in different laboratories are. This information has never been collected in a consistent way. The aim of the authors is to develop guidance on the mechanical properties of the Fallhammer, which can be used for different purposes such as internal quality control, validation of the correct functioning of the Fallhammer, preparation of Round-Robin tests and similar. An established and verified mechanical status of a Fallhammer would greatly improve the quality and comparability of results and Round-Robin tests on the impact sensitivity of explosives.
According to several recent studies, an unexpectedly high number of landmark papers seem to be not reproducible by Independent laboratories. Nontherapeutic antibodies used for research, diagnostic, food analytical, environmental, and other purposes play a significant role in this matter. Although some papers have been published offering suggestions to improve the situation, they do not seem to be comprehensive enough to cover the full complexity of this issue. In addition, no obvious improvements could be noticed in the field as yet. This article tries to consolidate the remarkable variety of conclusions and suggested activities into a more coherent conception. It is concluded that funding agencies and journal publishers need to take first and immediate measures to resolve these problems and lead the way to a more sustainable way of bioanalytical research, on which all can rely with confidence.