Mineral-impregnated carbon fiber composites (MCF) constitute a new type of reinforcement for construction. While inheriting the advantages of existing carbon fiber reinforcements, which are composite ...materials made of carbon filaments embedded in a thermoplastic or thermosetting matrix, MCF surpass the limitations of such polymer-impregnated types. More particularly, mineral impregnation considerably improves the performance of the reinforcement at elevated temperatures, enhances its bond to the concrete matrix, and increases technological flexibility, especially with respect to emerging automated production approaches. The article at hand presents the technology for continuous impregnation of carbon yarns with appropriately chosen fine mineral binder suspensions. Several examples for the automated manufacturing of reinforcement systems made of this new composite material are provided: one-dimensional elements such as bars and strips, two-dimensional reinforcements in the form of mats, and three-dimensional cases as examples of reinforcements for a balcony and shell elements. Furthermore, an outlook on introducing the novel reinforcement into highly automated, additive construction technologies is given.
•Mineral-impregnated, carbon fiber composite (MCF) is a new reinforcement material.•MCF exhibits excellent temperature resistance, durability and bond to concrete.•MCF opens numerous opportunities for highly automated and digitized technologies.•One-, two- and three-dimensional reinforcement elements can be produced.•Challenges with respect to up-scaling and full automation are discussed.
In an attempt to match US bankruptcy law, many European countries have reformed their insolvency laws towards a regime that fosters corporate restructuring. This paper evaluates the implications of ...these reforms. Based on a staggered difference-in-differences analysis around eight insolvency reforms in 15 European countries, this paper finds a relative increase in the cost of debt by about 50 bps in countries with such a reform. The effect is more pronounced among firms being closer to default. As a result of increased cost of debt financing, firms cut investment, innovation, and employee pay. In addition, firms are also more likely to turn into zombies post-treatment. Overall, the results are consistent with the view that creditors may be negatively affected by insolvency law reforms oriented towards restructuring and, thus, demand higher risk premia. This, in turn, causes real effects in the corporate sector.
Data mining in resistance spot welding Boersch, Ingo; Füssel, Uwe; Gresch, Christoph ...
International journal of advanced manufacturing technology,
11/2018, Letnik:
99, Številka:
5-8
Journal Article
Recenzirano
Resistance spot welding is the dominant process in the present mass production of steel constructions without sealing requirements with single sheet thicknesses up to 3 mm. Two of the main ...applications of resistance spot welding are the automobile and the railway vehicle manufacturing industry. The majority of these connections has safety-related character and therefore they must not fall below a certain weld diameter. Since resistance spot welding has been established, this weld diameter has been usually used as the gold standard. Despite intensive efforts, there has not been found yet a reliable method to detect this connection quality non-destructively. Considerable amounts of money and steel sheets are wasted on making sure that the process does not result in faulty joints. The indication of the weld diameter by in-process monitoring in a reliable way would allow the quality documentation of joints during the welding process and additionally lead through demand-actuated milling cycles to a substantial decrease of electrode consumption. An annual, estimated reduction in the seven- to nine-figure range could be achieved. It has an important impact, because the economics of the process is essentially characterized by the electrode caps (Klages
24
). We propose a simple and straightforward approach using data mining techniques to accurately predict the weld diameter from recorded data during the welding process. In this paper, we describe the methods used during data preprocessing and segmentation, feature extraction and selection, and model creation and validation. We achieve promising results during an analysis of more than 3000 classified welds using a model tree as a predictor with a success rate of 93 %. In the future, we hope to validate our model with unseen welding data and implement it in a real world application.
The reaction kinetics of the heterogeneously catalyzed esterification of n-hexyl acetate were measured using both a batch reactor and continuous stirred tank reactor (CSTR). The catalyst was ...Amberlyst CSP2. The results of the batch reactor and CSTR experiments were compared to reaction kinetic measurements carried out in previous work using a plug-flow reactor (PFR). Because the change in the composition of the reaction mixture in the batch reactor is caused not only by reaction but also by component-specific adsorption on the catalyst, the batch reactor is not recommended for reaction kinetic measurements of the present type of chemical system. The results from the CSTR and PFR are in very good agreement with regard to the measured rate of reaction. To address the impact of the conditions present in a heterogeneously catalyzed reactive distillation (HCRD) column on the performance of the catalyst, the influences of boiling and of the reduction of the low-boiling components (here, water) on the rate of reaction were investigated using the CSTR. Neither was found to have a significant impact on the performance of the catalyst. A simple pseudohomogeneous model was fitted to the data of the CSTR experiments using a reparameterized Arrhenius equation to avoid parameter coupling. The model predictions and experimental results are in good agreement.
► Measured data on structured packing efficiency often differ by more than 15–25%. ► This is due to the differences in equipment, test system, procedure and evaluation. ► The need for a common ...standard is obvious. ► A selection out of best practices available is proposed for a standard. ► Improved thermophysical correlations for chlorobenzene/ethylbenzene are proposed.
Distillation is the most important thermal separation process, with separation efficiency as one of the fundamental parameters to influence economy and energy consumption. The precise knowledge of separation efficiency and the ability to compare different types of column internals is vital information for the chemical industry. Still, total reflux distillation experiments are the only significant source of such data. The authors have taken the effort to work out in elaborate manner different factors influencing both measurement and interpretation of structured packing separation efficiency data, to provide basis for establishing an open standard in this respect. In addition, an improved set of thermophysical correlations for the test system chlorobenzene/ethylbenzene (CB/EB) is presented.
Data mining in resistance spot welding Boersch, Ingo; Füssel, Uwe; Gresch, Christoph ...
International journal of advanced manufacturing technology,
11/2018, Letnik:
99, Številka:
5
Journal Article
Recenzirano
Resistance spot welding is the dominant process in the present mass production of steel constructions without sealing requirements with single sheet thicknesses up to 3 mm. Two of the main ...applications of resistance spot welding are the automobile and the railway vehicle manufacturing industry. The majority of these connections has safety-related character and therefore they must not fall below a certain weld diameter. Since resistance spot welding has been established, this weld diameter has been usually used as the gold standard. Despite intensive efforts, there has not been found yet a reliable method to detect this connection quality non-destructively. Considerable amounts of money and steel sheets are wasted on making sure that the process does not result in faulty joints. The indication of the weld diameter by in-process monitoring in a reliable way would allow the quality documentation of joints during the welding process and additionally lead through demand-actuated milling cycles to a substantial decrease of electrode consumption. An annual, estimated reduction in the seven- to nine-figure range could be achieved. It has an important impact, because the economics of the process is essentially characterized by the electrode caps (Klages 24). We propose a simple and straightforward approach using data mining techniques to accurately predict the weld diameter from recorded data during the welding process. In this paper, we describe the methods used during data preprocessing and segmentation, feature extraction and selection, and model creation and validation. We achieve promising results during an analysis of more than 3000 classified welds using a model tree as a predictor with a success rate of 93 %. In the future, we hope to validate our model with unseen welding data and implement it in a real world application.
Mineralisch gebundene Carbonfaserbewehrung ist eine neue Art der Armierung für den Betonbau, die im Vergleich zu bestehenden, kunststoffgebundenen Carbonbewehrungen beträchtliche Vorteile aufweist. ...Die mineralische Imprägnierung erhöht die Leistungsfähigkeit der Bewehrung bei erhöhten Temperaturen, verbessert ihren Verbund mit der Betonmatrix und steigert deutlich die technologische Flexibilität, insbesondere im Hinblick auf die Digitalisierung und Automatisierung der Bauteilherstellung. Nach der Erläuterung der Technologie zur kontinuierlichen Imprägnierung von Carbongarnen mit speziell entwickelten, feinen mineralischen Bindemittelsuspensionen werden einige Beispiele für die automatisierte Herstellung von Bewehrungssystemen aus diesem neuen Verbundwerkstoff vorgestellt. Diese Fälle umfassen eindimensionale Elemente wie Stäbe und Lamellen, zweidimensionale Bewehrungen in Form von Matten und dreidimensionale Systeme wie Bewehrungskörbe für einen Balkon oder Schalenstrukturen. Schließlich wird kurz auf die Verwendung des neuartigen Komposits für die Bewehrung in hochautomatisierter additiver Fertigung wie Beton‐3D‐Druck eingegangen.
New Carbon Fiber Reinforcement for Digital, Automated Concrete Construction
Mineral‐impregnated carbon fiber (MCF) is a new type of reinforcement for concrete construction, which exhibit significant advantages in comparison to existing polymer‐based carbon fiber reinforcements. Mineral impregnation considerably improves the performance of the reinforcement at elevated temperatures, enhances its bond to the concrete matrix, and increases technological flexibility, especially with respect to digitized, automated production of concrete elements. First, the technology for continuous impregnation of carbon yarns with special fine mineral binder suspensions is explained. Then several examples for the automated manufacturing of reinforcement systems made of this new composite material are presented. These examples cover one‐dimensional elements such as bars and strips, two‐dimensional reinforcements in the form of mats, and three‐dimensional cases such as reinforcing cage for a balcony or shell elements. Finally, the use of the novel reinforcement in conjunction with highly automated, additive construction technologies such as 3D‐concrete‐printing is discussed.
In dieser Arbeit werden vier Wege aufgezeigt die Gebrauchsdauer von Elektroden zu verbessern. Der erste Weg besteht darin die tatsächlich verfügbare Standmenge zu nutzen, soweit es statische ...Fräszyklen ermöglichen. Vom aktuellen Orientierungswert, welcher bei 120 Punktschweißverbindungen für eine Standmenge liegt, lassen sich auf diesem Weg 70% an Elektroden beim Schweißen feuerverzinkter Stahlbleche einsparen. Auf dem zweiten Weg wird nachgewiesen, dass die Standard-CuCr1Zr-Legierung verbessert werden kann. Bereits mit geringsten Gefüge-Modifikationen lassen sich ein gutmütigeres Verschleißverhalten, eine größere Standmenge und ein charakteristischeres Standmengenende erzielen. Der dritte Weg beleuchtet dispersionsgehärtete Elektrodenkappen. Solche sind nicht neu, aber wurden in den 2000er Jahren weiterentwickelt. Ihr nun verfügbares Potential erlaubt gegenüber der ersten Betrachtung einen bis zu 95% verringerten Elektroden-Bedarf an feuerverzinkten Blechen. Abschließend formuliert der vierte Weg eine zukunftsweisende Möglichkeit die Standmenge dynamisch der real verfügbaren Standmenge anzupassen. Dieser Ansatz erlaubt einerseits Haftpflichtrisiken an mathematisches Vorgehen zu überantworten und andererseits das Werkstoffpotential vollständig zu nutzen. Da Streubreiten der realen Standmengengrenzen bei bis zu 40% liegen, ist eine entsprechende Einsparung an Kupfer erreichbar. In der vorliegenden Arbeit wird dazu der Ansatz verfolgt den Punktdurchmesser aus typischen Prozessgrößen mittels Data Mining zu bestimmen. Das fertigungsnahe Qualitätsband von +/-10% Punktdurchmesser kann basierend auf einem mathematisch transparenten Modell mit über 93% Wahrscheinlichkeit korrekt berechnet werden.
