@article{PecqueurMaltenbergerPetrukhinaetal.2016, author = {Pecqueur, S{\´e}bastien and Maltenberger, Anna and Petrukhina, Marina A. and Halik, Marcus and Jaeger, Arndt and Pentlehner, Dominik and Schmid, G{\"u}nter}, title = {Wide Band-Gap Bismuth-based p-Dopants for Opto-Electronic Applications}, series = {Angewandte Chemie International Edition}, journal = {Angewandte Chemie International Edition}, number = {55}, publisher = {Wiley-VCH Verlag}, address = {Weinheim}, year = {2016}, abstract = {Ten new efficient p-dopants for conductivity doping of organic semiconductors for OLEDs are identified. The key advantage of the electrophilic tris(carboxylato) bismuth(III) compounds is the unique low absorption of the resulting doped layers which promotes the efficiency of OLED devices. The combination of these features with their low fabrication cost, volatility, and stability, make these materials very attractive as dopants in organic electronics.}, language = {en} } @article{HirschmuellerPravidaMarteetal.2019, author = {Hirschm{\"u}ller, Sebastian and Pravida, Johann and Marte, Roman and Flach, Michael}, title = {Long-term material properties of circular hollow laminated veneer lumber sections under water saturation and cement alkaline attack}, series = {Wood Material Science and Engineering}, volume = {14}, journal = {Wood Material Science and Engineering}, number = {3}, pages = {142 -- 156}, year = {2019}, abstract = {Innovative beech laminated veneer lumber (LVL) circular hollow sections for the use as temporary geotechnical soil nailing systems are currently being developed. Due to the permanent subsoil cement embedment, combined with high water saturation and permanent loading, the timber sections will lose strength and stiffness over time to a degree currently unknown. This paper presents the tensile and bending material properties of flat and curved beech LVL under various periods of immersion in a water-cement grout solution aiming at inducing both water saturation and long-term alkaline attack of the timber. In total, 824 and 279 samples were tested in tension and bending, respectively. Results show that samples manufactured from 3 mm thick veneers result in tensile strength and stiffness 17\% and 24\% higher, respectively, than samples manufactured from 2 mm thick veneers. A reduction in the initial bending and tensile strength of up to 70\% was found after 90 days of water saturation and cement contact. Taking into account a duration of load factor for permanent loading of two years, it is recommended to reduce the short-term tensile and bending strength of beech circular hollow sections to be used as geotechnical anchors by 80\%.}, language = {en} } @article{Schemme2008, author = {Schemme, Michael}, title = {Longfibre reinforced thermoplastics - status and perspectives}, series = {Plastics, Additives and Compounding}, volume = {10}, journal = {Plastics, Additives and Compounding}, number = {2}, pages = {38 -- 43}, year = {2008}, language = {de} } @article{Schemme2008, author = {Schemme, Michael}, title = {LFT - development status and perspectives}, series = {Reinforced Plastics}, volume = {52}, journal = {Reinforced Plastics}, number = {1}, pages = {32 -- 39}, year = {2008}, language = {en} } @article{HirschmuellerMartePravidaetal.2018, author = {Hirschm{\"u}ller, Sebastian and Marte, Roman and Pravida, Johann and Flach, Michael}, title = {Inhibited wood degradation of cement-coated beech Laminated Veneer Lumber (LVL) for temporary in-ground applications.}, series = {European Journal of Wood and Wood Products}, volume = {76}, journal = {European Journal of Wood and Wood Products}, number = {5}, editor = {Springer,}, pages = {1483 -- 1494}, year = {2018}, abstract = {This paper investigates the long-term tensile properties of laminated veneer lumber (LVL) beech sections coated with cement and exposed to fungal decay. A set of LVL coupon (dog-bone) samples was stored in compost, tested in tension after 6 and 12 months and compared to reference samples stored at 20 °C and 65\% relative humidity. Results showed that after 26 weeks of compost exposure, a fungus of the Ascomycota genus was identified in cement-coated samples using a molecular biology polymerase chain reaction (PCR) technique, which analyses the internal transcribed spacer (ITS) region of the ribosomal DNA. However, no visual deterioration was noticed. Still in cement-covered samples and after 12 months of exposure, a common white rot fungus was determined by DNA chip technology, but no fungal wood decay was visible in areas where the applied coating had a thickness of at least 5 mm. Decay in uncoated LVL samples was significant with the samples having an average residual strength equal to 7\%. This compares to the tensile strength of coated samples, which only decreased by 65\% relative to the reference samples. Strength and stiffness of coated samples did not differ significantly between 6 and 12 months of exposure. Preliminary investigations tend to show that the strength reduction in cement-coated samples is due to an alkaline degradation of the wood. The observed influence of the coating thickness on the visual fungal decay can probably be ascribed to the protection mechanism due to a physical fungal barrier with a high pH.}, language = {en} } @article{KrommesTomaschko2021, author = {Krommes, Sandra and Tomaschko, Florian}, title = {Chance f{\"u}r mehr Ressourceneffizienz - Methode der Wert- und Stoffstromanalyse im Kontext der digitalen Transformation bestehender Fertigungsanlagen}, series = {Zeitschrift f{\"u}r wirtschaftlichen Fabrikbetrieb (zwf)}, volume = {116}, journal = {Zeitschrift f{\"u}r wirtschaftlichen Fabrikbetrieb (zwf)}, number = {1-2}, publisher = {De Gruyter}, address = {Berlin}, pages = {58 -- 63}, year = {2021}, abstract = {Die dynamische Wert- und Stoffstrommodellierung bildet die In- und Output-Str{\"o}me von Prozessen mittels Digitalisierungstechnologien ab. In einem aus f{\"u}nf Schritten bestehenden methodischen Vorgehen kann der Einstieg in die Digitalisierung der Produktion f{\"u}r KMU mit bestehenden Anlagen- und Maschinenparks (Brownfield-Ansatz) gelingen: Ein digitaler Schatten erm{\"o}glicht ein echtzeit- und realdatenbasiertes Monitoring von Einzel- und Kleinserienfertigungen zur Steigerung der Ressourceneffizienz. Method of Value and Material Flow Analysis within the Digital Transformation of a Brownfield Approach. Dynamic value and material flow modeling maps input and output flows of processes by means of digitization. In a methodical approach consisting of five steps, SMEs with existing plant and machine parks (brownfield approach) can be successfully introduced to the digitization of production: A digital shadow of a defined process enables a real-time and real data-based monitoring and key figure system for individual and small series production.}, language = {de} } @article{LazarJarre2016, author = {Lazar, Markus and Jarre, F.}, title = {Calibration by Optimization Without Using Derivatives}, series = {Optimization and Engineering}, volume = {2016}, journal = {Optimization and Engineering}, number = {17/4}, publisher = {Springer}, pages = {833 -- 860}, year = {2016}, abstract = {Applications in engineering frequently require the adjustment of certain parameters. While the mathematical laws that determine these parameters often are well understood, due to time limitations in every day industrial life, it is typically not feasible to derive an explicit computational procedure for adjusting the parameters based on some given measurement data. This paper aims at showing that in such situations, direct optimization offers a very simple approach that can be of great help. More precisely, we present a numerical implementation for the local minimization of a smooth function f:Rn→R subject to upper and lower bounds without relying on the knowledge of the derivative of f. In contrast to other direct optimization approaches the algorithm assumes that the function evaluations are fairly cheap and that the rounding errors associated with the function evaluations are small. As an illustration, this algorithm is applied to approximate the solution of a calibration problem arising from an engineering application. The algorithm uses a Quasi-Newton trust region approach adjusting the trust region radius with a line search. The line search is based on a spline function which minimizes a weighted least squares sum of the jumps in its third derivative. The approximate gradients used in the Quasi-Newton approach are computed by central finite differences. A new randomized basis approach is considered to generate finite difference approximations of the gradient which also allow for a curvature correction of the Hessian in addition to the Quasi-Newton update. These concepts are combined with an active set strategy. The implementation is public domain; numerical experiments indicate that the algorithm is well suitable for the calibration problem of measuring instruments that prompted this research. Further preliminary numerical results suggest that an approximate local minimizer of a smooth non-convex function f depending on n≤300 variables can be computed with a number of iterations that grows moderately with n.}, language = {en} } @article{PecqueurMaltenbergerPetrukhinaetal.2016, author = {Pecqueur, S{\´e}bastien and Maltenberger, Anna and Petrukhina, Marina A. and Halik, Marcus and Jaeger, Arndt and Pentlehner, Dominik and Schmid, G{\"u}nter}, title = {Bismut-haltige p-Dotanden mit großer Bandl{\"u}cke f{\"u}r optoelektronische Anwendungen}, series = {Angewandte Chemie}, journal = {Angewandte Chemie}, number = {128(35)}, publisher = {Wiley-VCH Verlag}, address = {Weinheim}, year = {2016}, abstract = {Zehn neue p-Dotanden f{\"u}r die Leitf{\"a}higkeitsdotierung von organischen Halbleitern wurden identifiziert. Der wesentliche Vorteil der elektrophilen Tris(carboxylato)-Bismut(III)-Verbindungen ist die niedrige Absorption der damit dotierten Schichten. Diese Eigenschaft zusammen mit ihren niedrigen Herstellungskosten sowie der guten Verdampfbarkeit und Stabilit{\"a}t macht diese Dotanden sehr attraktiv f{\"u}r Anwendungen in der organischen Elektronik.}, language = {de} } @article{HummelObermeierZieretal.2022, author = {Hummel, Sabine and Obermeier, Katharina and Zier, Katja and Krommes, Sandra and Schemme, Michael and Karlinger, Peter}, title = {Analysis of Mechanical Properties Related to Fiber Length of Closed-Loop-Recycled Offcuts of a Thermoplastic Fiber Composites (Organo Sheets)}, series = {Materials}, volume = {15}, journal = {Materials}, number = {11}, pages = {3872}, year = {2022}, abstract = {Increasing demand for energy-efficient means of transport has steadily intensified the trend towards lightweight components. Thermoplastic glass fiber composites (organo sheets) play a major role in the production of functional automotive components. Organo sheets are cut, shaped and functionalized by injection molding to produce hybrid components, such as those used in car door modules. The cutting process produces a considerable amount of production waste, which has thus far been thermally recycled. This study develops a closed mechanical recycling process and analyzes the different steps of the process. The offcuts were shredded using two shredding methods and implemented directly in the injection-molding process. Using tensile tests and impact bending tests, the material properties of the recycled materials were compared with the virgin material. In addition, fiber length degradation via the injection-molding process and the influence of the waterjet-cutting process on the mechanical properties are investigated. Recycled offcuts are both comparable to new material in terms of mechanical properties and usability, and are also economically and ecologically advantageous. Recycling polypropylene waste with glass fiber reinforcement in a closed loop is an effective way to reduce industrial waste in a sustainable and economical production process.}, language = {en} } @article{HirschmuellerPravidaMarteetal.2018, author = {Hirschm{\"u}ller, Sebastian and Pravida, Johann and Marte, Roman and Flach, Michael}, title = {Adhesive properties of laminated veneer lumber poles for use in temporary soil nailing: development and evaluation of a test method for curved structures in a high-alkaline environment}, series = {Wood Science and Technology}, volume = {52}, journal = {Wood Science and Technology}, number = {4}, editor = {Springer,}, pages = {1061 -- 1092}, year = {2018}, abstract = {Innovative circular, hollow, laminated veneer lumber (LVL) beech sections for use as temporary geotechnical soil reinforcement members are currently being developed. Appropriate surface gluing quality between the veneers is fundamental to this subsoil application of the permanently cement-embedded, engineered timber product. The circular cross-section geometry and the permanently high-alkaline environment of the structural member is not covered by presently standardized testing and conditioning methods for examining LVL surface bond line quality. The sample conditioning and tensile shear test method compliant with EN 302-1 (Adhesives for load-bearing timber structures—test methods—part 1: determination of longitudinal tensile shear strength, European Committee for Standardization, Brussels, 2013) was modified to determine bonding parameters for circular, hollow LVL sections. Bond line curvature, groove cutting depth and sample geometry were found to greatly influence stress distribution, percentage of wood failure and tensile shear strength. Short-term alkaline treatment of test samples did not significantly influence the bonding performance, wood failure percentage, tensile shear strength and fracture patterns. To improve tensile shear strength, adhesives with different material rigidities were used and compared. An orthotropic, elastic numerical analysis revealed a greater influence of adherent elasticity than adhesive elasticity on the stress distribution within the bond line. With regard to determining the bond line integrity of curved veneer poles, a sample geometry compliant with EN 302-1 (2013) was developed and numerically evaluated.}, language = {en} }