Saint-Gobain (Germany)

Grinding offers capabilities that range from high-rate material removal to high-precision superfinishing, and has become one of the most widely used industrial machining and surface finishing operations. Reflecting modern developments in the science and practice of modern grinding processes, the Handbook of Machining with Grinding Wheels presents a

A major challenge of today's production systems in the context of Industry 4.0 and Cyber-Physical Production Systems is to be flexible and adaptive whilst being robust and economically efficient. Specifically, the implementation of motion planning processes for industrial robots need to be refined concerning their variability of the motion task and the ability to adaptively deal with variations in the environment. In this paper, we propose a reinforcement learning (RL) based, cognition-enhanced six-axis industrial robot for complex motion planning along continuous trajectories as e.g. needed for welding, gluing or cutting processes in production. Our prototype demonstrator is inspired by the classic wire loop game which involves guiding a metal loop along the path of a curved wire from start to finish while avoiding any contact between the wire and the loop. Our work shows that the RL-agent is capable of learning how to control the robot to successfully play the wire loop game without the need of modeling the wire or programming the robot motion beforehand. Furthermore, the extension of the system by a visual sensor (a camera) allows the agent to sufficiently generalize the learning problem so that it can solve new or reshaped wires without the need of additional learning. We conclude that the applicability of RL for industrial robots and production systems in general provides vast and unexplored potential for processes that feature variability to some extent and thus require a general and robust approach for process automation.

The paper initially reviews research relating to ultrasonic (US) assisted grinding of various workpiece materials. Results from experimental trials to evaluate the influence of applying US vibration when creep feed grinding Inconel 718 with an open structured, alumina based grinding wheel (POROS 2) are then presented. A full factorial experimental array comprising 18 runs was conducted involving variation in wheel speed (30, 35 and 40m/s), table speed (200, 250 and 300 mm/min) and grinding condition (with and without vibration). For tests with US vibration, the workpiece was actuated at a constant frequency (∼20 kHz) via a specially designed block sonotrode attached to a 1 kW piezoelectric transducer-generator system. Reductions in vertical (FV) and horizontal (FH) grinding force components of up to 23% and 43% for FV and FH respectively and surface roughness (Sa) of the ground slots by up to 45% were observed in the majority of tests when utilising US assisted operation. In terms of surface quality, SEM micrographs revealed greater side flow/ploughing and overlapping grit marks in slots machined with the workpiece vibrated in comparison to standard creep feed ground specimens. Three dimensional topographic measurement of grinding wheel surface replicas indicated that US vibration led to an increase in the number of active cutting points on the wheel.

The paper details the effects of depth of cut and vibration amplitude when ultrasonic assisted (US) creep feed grinding Inconel 718 with an open structured alumina based wheel. The workpiece was actuated at a constant frequency (∼20.5kHz) via a block sonotrode attached to a 1kW piezoelectric transducer-generator system. A full factorial experimental array comprising 12 tests was conducted involving variation in depth of cut (0.1, 0.5 and 1.0mm), amplitude of vibration (high and low) and grinding condition (with and without vibration). Wheel speed and table feed were fixed at 30m/s and 600mm/min respectively for all tests. Application of ultrasonic vibration resulted in reductions in vertical (F) and horizontal (F) force components by up to 28% and 37% respectively, however greater wheel wear (30-60% lower G-ratio) occurred under hybrid operation due to increased grit/bond fracture. SEM micrographs of the slots machined with US assistance revealed higher levels of side flow/ploughing in comparison to standard creep feed ground specimens. Additionally, more overlapping grit marks were visible on surfaces subject to ultrasonic assisted grinding. Increasing amplitude of vibration produced lower grinding forces (up to 30% for F and 43% for F ) but higher workpiece surface roughness (up to 24%). Topographic maps of grinding wheel surface replicas indicated that use of US vibration generally led to an increase in the number of active cutting points on the wheel.

The present study focuses on the drying of droplets of colloidal suspensions using the Leidenfrost effect. At the end of drying, grains show different morphologies: cups or spheres depending on the ionic strength or zeta potential of the initial suspension. High ionic strengths and low absolute zeta potential values lead to spherical morphologies. A model based on the calculations of DLVO potentials has been implemented to extract a critical pressure, which provides a quantitative criterion for buckling whatever the initial formulation is. Particularly, the buckling time is quantitatively predicted from the interparticle interactions and shows an excellent agreement with experimental values.

This study comprises the testing of three auto body steels with regard to formability, tensile strength and forming limits under various stress states. Two multiphase steels (DP600, TRIP700) and one ferritic interstitial free (DX54, 1.0306) were characterised. A further main focus of this study is the comparison of experimentally determined flow curves in the bulge test with extrapolated tensile test flow curves. This comparison gives an insight into the predictability and accuracy of extrapolated curve progressions to higher strain ranges.

The intermediate-energy scanning x-ray microscope at beamline 2-ID-B at the Advanced Photon Source is a dedicated instrument for materials and biological research. The microscope uses a zone plate lens to focus coherent I-4 keV x-rays to a 60 nm focal spot of 10 9 photons/ s onto the sample. It records simultaneous transmission and energy-resolved fluorescence images. We have used the microscope for nanotomography of chips and microspectroscopy of cells.

Spontaneous breakage of glass in facades is under control today, due to application of a very effective prevention method, namely the Heat Soak Test (HST) following EN 14179-1 (2006/2016). Nevertheless, details of the latter are still subject to discussion, mainly due to the fact that some years ago, it was discovered in an R&D project that it’s holding temperature is too high, and it was reduced to $$260 \pm 10\,^\circ \hbox {C}$$ at the recent review. In the present paper we investigate the properties of nickel sulphide inclusions in order to show that there’s a huge difference in their comportment, and therewith their “criticality”, in the HST or on the façade. Namely, not only the expansivity difference between nickel sulphide and the glass plays a role. Nickel sulphide inclusions show a spectrum of possible compositions, and we approach this fact systematically, showing how the breakage probability under both conditions changes depending on the detailed composition of the inclusions. The result of this comparison is that, out of all nickel sulphide inclusions leading to breakage in HST, only 40% also lead to breakage at ambient. Another aspect is the time-to-breakage curve in the HST. By the example of a dataset where nearly only SiO$$_2$$ stones cause breakages therein, we show that not only the $$\upalpha $$ to $$\upbeta $$ transformation of NiSx causes these breakages. Also the HST process itself, through the fact that it’s impossible to heat up the glass panes therein in an absolutely homogeneous way, adds significant thermo-mechanic forces leading to boosting the breakages more than possible on façades. Besides this, also the potential impact of sub-critical crack growth at HST temperature is discussed. We conclude that the actual estimation of the residual breakage probability of Heat-Soak Tested Thermally Toughened Glass (according to EN 14179-1) is much too high, needs major revision, and until then, can only be looked at to be a lower limit with high safety margin of the real safety of this product. The present paper will be completed by at least two additional papers dealing with the detection of nickel sulphide inclusions in annealed glass and, on the other hand, a new way to evaluate statistically the data from nickel sulphide inclusion caused breakages.

Condition-based maintenance (CBM) has emerged as a proactive strategy for determining the best time for maintenance activities. In this paper, a case of a milling process with imperfect maintenance at a German automotive manufacturer is considered. Its major challenge is that only data with missing labels are available, which does not provide a sufficient basis for classical prognostic maintenance models. To overcome this shortcoming, a data science study is carried out that combines several analytical methods, especially from the field of machine learning (ML). These include time-domain and time–frequency domain techniques for feature extraction, agglomerative hierarchical clustering and time series clustering for unsupervised pattern detection, as well as a recurrent neural network for prognostic model training. With the approach developed, it is possible to replace decisions that were made based on subjective criteria with data-driven decisions to increase the tool life of the milling machines. The solution can be employed beyond the presented case to similar maintenance scenarios as the basis for decision support and prognostic model development. Moreover, it helps to further close the gap between ML research and the practical implementation of CBM.

Through the H2020 BE-SMART project, we work on the validation and industrialization of new materials (and processes) for manufacturing next-generation cost-efficient, reliable and highly aesthetic/performing BIPV. On this basis, we aim at introducing novel multifunctional and transformative BIPV elements, in the concept/form of Energy Positive Glazing (EPoG). The project's developments so far indicate the high potential of e.g. using colored encapsulants, interferential filter technique and/or ceramic-based colored glazing for implementing novel “transformative” BIPV with high aesthetic quality. Yet, since BIPV's primary function is electricity production, we need to understand and quantify the impact of such coloration solutions on the performance (and reliability, in longer terms) of future BIPV. In this paper, we present an experimental comparative study on the optical and electrical performance of multiple color coated and patterned BIPV glazing solutions, towards their upscaling and commercialization. In particular, we performed optical transmission measurements and light intensity-/angle-depent IV characterization on 25 different colored glass samples and 10 different colored/patterned glass PV laminates respectively. The measurement results and their discussion presented in this paper provide valuable insights into the optical-electrical performance of the investigated colored BIPV glazing, as well as a first identification of BIPV industry-relevant colors and patterns with the best potential “compromise” between aesthetics and performance, for future energy positive glazing applications.

Understanding the role of lattice oxygen in CO oxidation over ceria-based compounds, revealed by the combination of novel isotope-based techniques, ILARS and ILPOR.

The objective of this work is the development of a front cover glass for all types of PV modules allowing a significant reduction of optical losses at the glass-air and the polymer-cell interface. The annual relative gain in transmission between a plane surface and a inverse pyramidal-textured (half-angle=45/spl deg/) surface has been calculated to be 8.1% for direct radiation and 6.1% for diffuse radiation for a standard year in Cologne (Germany). This glass has been manufactured on an industrial cast glass furnace during an extra-white campaign. It allows an annual efficiency improvement of 3.1% (2.9% at normal incidence and 9.4% at 70/spl deg/) compared to flat glass with the same composition and measured with polycrystalline Si solar cells. After 9 months outdoor testing (on a dusty test site, 60/spl deg/ tilted to a horizontal surface), a significant advantage of the pyramidal glass (compared to flat glass) is still present.

In many energy-intensive manufacturing processes, natural gas is the dominant fuel to provide process heat. There is increasing pressure, however, to reduce both fuel costs and carbon dioxide (CO2) emissions. One possible approach in this regard is the use of mostly untreated biogas as a fuel in a co-firing approach. While the use of such biogas can decrease both natural gas consumption and overall CO2 emissions (biogas is considered to be a CO2-neutral fuel), there is concern how this change of fuel will impact on product quality, combustion behavior and the refractory material. Trace contaminations in the biogas are one aspect in this context which might have a negative impact on product quality or the durability of the refractory of industrial furnaces. In a previous research project, GWI and its partners investigated the principal applicability of biogas combustion, using the glass melting process as an example. It was found that there was no negative impact on combustion behavior, product quality or refractory properties if the process is adapted to the different characteristics of the fuel, for example by adjusting melting times. Another result was that for existing plants, it is more sensible to use a co-firing approach, partly substituting natural gas by biogas, instead of switching fuels completely. Consequently, the co-firing of roughly de-sulphurized biogas in an industrial glass melting furnace in Germany is currently being investigated as part of a follow-up project. Aspects such as pollutant formation, energy efficiency and product quality when using untreated biogas on an industrial scale will be examined.

This investigation into the effects on teachers of the natural work “noise” occurring in lessons is based on an analysis of the altered pedagogical approach in everyday school life (cf. Oberdörster/Tiesler: “Modern Teaching” needs modern conditions). Is it correct to speak in general of “noise stress” or is this stress more an emotional reaction to the kind of work in which teachers are engaged? Based on recordings taken in 175 lessons this article describes how room acoustic conditions influence the teachers' measurable physiological load in relation to classroom events, teaching method and shares of speech. The data are resolved into 5-minute time slices for analysis. We analysed different conditions in one primary school (School 1) on the basis of four classrooms with a RT of > 0.5 s and four classrooms with a RT of < 0.5 s. At a second primary school (School 2) we analysed the effects of the room acoustic refurbishment (reverberation time reduced from 0.7 s to 0.4 s). Database are continuously recorded SPL, teaching activity and teacher's heart rate. Hence it is possible for the first time to consider classroom events and their effects on the teachers as a process. These physiological effects have to be confirmed by the reaction of students.

The thermal stability of gypsum-based materials, and in this context, especially their long-term behavior, is the background of our current research activities. A comprehensive investigation program was compiled in which detailed examinations of various model materials exposed to thermal loads were carried out. The understanding of the partly not entirely consistent state of knowledge shall be sharpened especially by in situ observations of the thermally induced conversion reaction of gypsum into hemihydrate. The temporal course of the reaction was investigated non-destructively by in situ investigations in a high-resolution X-ray computed tomography setup, and the experiment was accompanied by detailed characterizations of the microstructure and composition. In this contribution, selected results of experiments with a high-purity natural gypsum rock as the model substance are presented. Studying the influence of temperature on the reaction showed that, even under supposedly dry conditions, the reaction could take place at much lower temperatures than usually reported in the literature. It was demonstrated that the transformation of gypsum into hemihydrate could take place at a temperature of already 50 °C. The results indicated that even under "classical" heating conditions in a conventional oven, the dissolution and crystallization processes in water films on the mineral surfaces could be suggested to be a driving force for the reaction. A corresponding reaction model, which took these aspects into account, was proposed in this work.

<div class="htmlview paragraph">As Diesel Particulate Filter (DPF) applications become widespread, the need for downsizing of filters increases. Indeed, downsizing allows reducing both filter and system costs, facilitates filter integration in the exhaust line close to the engine, and reduces overall system mass and potentially the precious metal loading.</div> <div class="htmlview paragraph">Filter downsizing is mainly limited by filter thermo-mechanical resistance because the system must be capable of storing enough soot before being forced to start filter regeneration in order to limit oil dilution and fuel consumption. The interval between two regenerations depends on filter maximum soot load (MSL) and volume. Thus, it is desired to increase filter MSL in order to keep long regeneration intervals with minimum filter volume. Moreover, in order to maintain acceptable backpressure on a loaded filter, it is required to use optimized cell geometries allowing significant pressure drop reductions.</div> <div class="htmlview paragraph">The current criterion used to define MSL is the appearance of the first crack inside the filter. This criterion is too conservative for recrystallized silicon carbide (RSiC) filters. Indeed, durability and robustness tests performed on RSiC filters show that it is possible to use a higher soot mass than the current MSL without degrading filter functional properties such as filtration efficiency and pressure drop. Therefore, filter downsizing is possible, but it is necessary to reduce filter pressure drop when it is loaded with soot. To do this, cell geometry has been optimized by increasing cell density and reducing wall thickness. Asymmetrical design is also maintained to guarantee good ash storage capacity. This new optimized filter enables a filter volume reduction of 20% while maintaining the same level of performance.</div>

The present paper is part two of a small series of three publications on spontaneous breakages of toughened glass. In part one, we deal with the detailed effects of the crystallographic and physical properties of the nickel sulphide species contained in those inclusions; we find that solely under this aspect, only c. 40% of the breakages in a Heat Soak Test (HST) according to, e.g., EN 14179-1:2006, would be physically able to cause a breakage in a façade. The present paper partly builds up on these findings. In the present paper, we prove experimentally that nickel sulphide inclusions are found everywhere in the raw glass section. On the other hand, their repartition is visibly influenced by gravitational settling. The resulting distribution profile is explained by a physical model. Further elaboration of this model allows to better understand the observed nickel sulphide inclusion size distribution in the raw glass. We show statistically that almost only nickel sulphide inclusions with size $$>55~\upmu \hbox {m}$$, situated in the middle glass portion, can lead to breakage in HST, in good correlation with data previously published. We quantify the nickel sulphide inclusions’ size impact based on the statistical evaluation of our dataset. Big nickel sulphide inclusions ($$>450~\upmu \hbox {m}$$) always cause very high breakage risk $$> 90\%$$. On the other hand, we prove experimentally that only a minority of c. 1/4 of the nickel sulphide inclusions factually existing in raw glass leads to breakages in the HST carried out in the frame of our R&D project where the glass panes were only small and thin. In the normal building glass product mix this proportion is probably higher because in the HST, the mass-related breakage rate (in numbers per ton of glass) increases with increasing glass panes’ dimensions. In Part Three we evaluate datasets from field breakages and give an overall summary of the series.

The present paper is the third part of a small series of publications dealing with the problem of spontaneous breakage of thermally toughened glass. The HST standard EN 14179-1:2005 (revised 2017) made this glass significantly safer; the present small series aims primarily to bring new arguments into the discussion on its real safety. Another aim is to rectify obsolete (pseudo-)facts repeated again and again in respective publications although they are disproven since a long time. The present third part of the series deals with statistic evaluation of datasets from field breakages. In these, every inclusion has caused a breakage, contrariwise to those in the 2nd part. The data have already been partly (and as one mixed dataset) published in 1997; since then, the author’s working group continued accumulating breakage data. Today, finally, this data collection is sufficiently numerous to be split into the two parts, namely breakages recorded on buildings and in Heat Soak Test, and to be evaluated separately by means of statistical analysis. Like in the previous papers, also this evaluation results in a clear difference in breakage probability, very much higher in HST. As a matter of fact, the latter’s breakages’ devolution cannot simply be extrapolated in order to obtain the safety of the tested glass on buildings; the result of this extrapolation is only a minimum limit, but factually far away from reality. Finally, the experience of the author’s employer, Saint-Gobain in Germany, is described for the time since the introduction of said standard. Also this pragmatic approach reveals that the safety of Heat-Soak Tested Thermally Toughened Safety glass against spontaneous breakages is much better than forecasted from the HST breakages’ evaluation.

Ru and AuRu nanoparticles were prepared by a sol-immobilization methodology and deposited on different doped zirconia supports (ZrO₂, Y–ZrO₂and La–ZrO₂).

A simple route towards patchy particles with anisotropic patches with respect to a different functionality and directionality is presented. This method is based on microcontact printing of positively charged polyethylenimine (PEI) on silica particles using wrinkled stamps. Due to the wrinkled surface, the number of patches on the particles as well as the distance between two patches can be controlled.