@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{ChristiansenNielsenChristensenetal.2016, author = {Christiansen, Lars and Nielsen, Jens H. and Christensen, Lauge and Shepperson, Benjamin and Pentlehner, Dominik and Stapelfeldt, Henrik}, title = {Laser-induced Coulomb explosion of 1,4-diiodobenzene molecules: Studies of isolated molecules and molecules in helium nanodroplets}, series = {Physical Review A}, journal = {Physical Review A}, number = {93}, year = {2016}, abstract = {Coulomb explosion of 1,4-diiodobenzene molecules, isolated or embedded in helium nanodroplets, is induced by irradiation with an intense femtosecond laser pulse. The recoiling ion fragments are probed by time-of-flight measurements and two-dimensional velocity map imaging. Correlation analysis of the emission directions of I+ ions recoiling from each end of the molecules reveals significant deviation from axial recoil, i.e., where the I+ ions leave strictly along the I-I symmetry axis. For isolated molecules, the relative angular distribution of the I+ ions is centered at 180∘, corresponding to perfect axial recoil, but with a full width at half maximum of 30∘. For molecules inside He droplets, the width of the distribution increases to 45∘. These results provide a direct measure of the accuracy of Coulomb explosion as a probe of the spatial orientation of molecules, which is particularly relevant in connection with laser-induced molecular alignment and orientation. In addition, our studies show how it is possible to identify fragmentation pathways of the Coulomb explosion for the isolated 1,4-diiodobenzene molecules. Finally, for the 1,4-diiodobenzene molecules in He droplets, it is shown that the angular correlation between fragments from the Coulomb explosion is preserved after they have interacted with the He environment.}, language = {en} } @article{ChristiansenNielsenPentlehneretal.2015, author = {Christiansen, Lars and Nielsen, Jens H. and Pentlehner, Dominik and Underwood, Jonathan G. and Stapelfeldt, Henrik}, title = {Alignment enhancement of molecules embedded in helium nanodroplets by multiple laser pulses}, series = {Physical Review A}, journal = {Physical Review A}, number = {92}, year = {2015}, abstract = {We show experimentally that field-free one-dimensional (1D) alignment of 1,4-diiodobenzene molecules embedded in helium nanodroplets, induced by a single, linearly polarized 200-fs laser pulse, can be significantly enhanced by using two or four optimally synchronized laser pulses. The strongest degree of 1D alignment is obtained with four pulses and gives ⟨cos2θ⟩>0.60. Besides the immediate implications for molecular frame studies, our results pave the way for more general manipulation of rotational motion of molecules in He droplets.}, language = {en} } @article{PentlehnerSlenczka2015, author = {Pentlehner, Dominik and Slenczka, Alkwin}, title = {Helium induced fine structure in the electronic spectra of anthracene derivatives doped into superfluid helium nanodroplets}, series = {The Journal of Chemical Physics}, journal = {The Journal of Chemical Physics}, number = {142}, year = {2015}, abstract = {Electronic spectra of organic molecules doped into superfluid helium nanodroplets show characteristic features induced by the helium environment. Besides a solvent induced shift of the electronic transition frequency, in many cases, a spectral fine structure can be resolved for electronic and vibronic transitions which goes beyond the expected feature of a zero phonon line accompanied by a phonon wing as known from matrix isolation spectroscopy. The spectral shape of the zero phonon line and the helium induced phonon wing depends strongly on the dopant species. Phonon wings, for example, are reported ranging from single or multiple sharp transitions to broad (Δν > 100 cm-1) diffuse signals. Despite the large number of example spectra in the literature, a quantitative understanding of the helium induced fine structure of the zero phonon line and the phonon wing is missing. Our approach is a systematic investigation of related molecular compounds, which may help to shed light on this key feature of microsolvation in superfluid helium droplets. This paper is part of a comparative study of the helium induced fine structure observed in electronic spectra of anthracene derivatives with particular emphasis on a spectrally sharp multiplet splitting at the electronic origin. In addition to previously discussed species, 9-cyanoanthracene and 9-chloroanthracene will be presented in this study for the first time.}, language = {en} } @article{PremkeWirthsPentlehneretal.2014, author = {Premke, Tobias and Wirths, Eva-Maria and Pentlehner, Dominik and Riechers, Ricarda and Lehnig, Rudolf and Vdovin, Alexander and Slenczka, Alkwin}, title = {Microsolvation of molecules in superfluid helium nanodroplets revealed by means of electronic spectroscopy}, series = {Frontiers in Chemistry}, volume = {2014}, journal = {Frontiers in Chemistry}, number = {2}, year = {2014}, abstract = {The empirical model explaining microsolvation of molecules in superfluid helium droplets proposes a non-superfluid helium solvation layer enclosing the dopant molecule. This model warrants an empirical explanation of any helium induced substructure resolved for electronic transitions of molecules in helium droplets. Despite a wealth of such experimental data, quantitative modeling of spectra is still in its infancy. The theoretical treatment of such many-particle systems dissolved into a quantum fluid is a challenge. Moreover, the success of theoretical activities relies also on the accuracy and self-critical communication of experimental data. This will be elucidated by a critical resume of our own experimental work done within the last ten years. We come to the conclusion that spectroscopic data and among others in particular the spectral resolution depend strongly on experimental conditions. Moreover, despite the fact that none of the helium induced fine structure speaks against the empirical model for solvation in helium droplets, in many cases an unequivocal assignment of the spectroscopic details is not possible. This ambiguity needs to be considered and a careful and critical communication of experimental results is essential in order to promote success in quantitatively understanding microsolvation in superfluid helium nanodroplets.}, language = {en} } @article{HansenOmisteNielsenetal.2013, author = {Hansen, Jonas and Omiste, Juan J. and Nielsen, Jens H. and Pentlehner, Dominik and K{\"u}pper, Jochen and Gonz{\´a}lez-F{\´e}rez, Rosario and Stapelfeldt, Henrik}, title = {Mixed-field orientation of molecules without rotational symmetry}, series = {The Journal of Chemical Physics}, journal = {The Journal of Chemical Physics}, number = {139}, year = {2013}, abstract = {The mixed-field orientation of an asymmetric-rotor molecule with its permanent dipole moment nonparallel to the principal axes of polarizability is investigated experimentally and theoretically. We find that for the typical case of a strong, nonresonant laser field and a weak static electric field complete 3D orientation is induced if the laser field is elliptically polarized and if its major and minor polarization axes are not parallel to the static field. For a linearly polarized laser field solely the dipole moment component along the most polarizable axis of the molecule is relevant resulting in 1D orientation even when the laser polarization and the static field are nonparallel. Simulations show that the dipole moment component perpendicular to the most-polarizable axis becomes relevant in a strong dc electric field combined with the laser field. This offers an alternative approach to 3D orientation by combining a linearly polarized laser field and a strong dc electric field arranged at an angle equal to the angle between the most polarizable axis of the molecule and its permanent dipole moment.}, language = {en} } @article{RiechersPentlehnerSlenczka2013, author = {Riechers, Rudolf and Pentlehner, Dominik and Slenczka, Alkwin}, title = {Microsolvation in superfluid helium droplets studied by the electronic spectra of six porphyrin derivatives and one chlorine compound}, series = {The Journal of Chemical Physics}, journal = {The Journal of Chemical Physics}, number = {138}, year = {2013}, abstract = {After almost two decades of high resolution molecular spectroscopy in superfluid helium droplets, the understanding of microsolvation is still the subject of intense experimental and theoretical research. According to the published spectroscopic work including microwave, infrared, and electronic spectroscopy, the latter appears to be particularly promising to study microsolvation because of the appearance of pure molecular transitions and spectrally separated phonon wings. Instead of studying the very details of the influence of the helium environment for one particular dopant molecule as previously done for phthalocyanine, the present study compares electronic spectra of a series of non-polar porphyrin derivatives when doped into helium droplets consisting of 104-105 helium atoms. Thereby, we focus on the helium-induced fine structure, as revealed most clearly at the corresponding electronic origin. The interpretation and the assignment of particular features obtained in the fluorescence excitation spectra are based on additional investigations of dispersed emission spectra and of the saturation behavior. Besides many dopant-specific results, the experimental study provides strong evidence for a particular triple peak feature representing the characteristic signature of helium solvation for all seven related dopant species.}, language = {en} } @article{PentlehnerNielsenChristiansenetal.2013, author = {Pentlehner, Dominik and Nielsen, Jens H. and Christiansen, Lars and Slenczka, Alkwin and Stapelfeldt, Henrik}, title = {Laser Induced Adiabatic Alignment of Molecules Dissolved in Helium Nanodroplets}, series = {Physical Review A}, journal = {Physical Review A}, number = {87}, year = {2013}, abstract = {A moderately intense, nonresonant, linearly polarized nanosecond laser pulse is used to induce one-dimensional (1D) adiabatic alignment of 1,4 diiodobenzene (C6H4I2), iodobenzene (C6H5I), and methyliodide (CH3I) molecules dissolved in helium nanodroplets. The alignment sharpens as the laser intensity is increased, similar to the behavior in gas phase. For diiodobenzene the highest degree of alignment, ⟨cos2θ2D⟩=0.90, is essentially identical to the value obtained for isolated molecules in a supersonic beam, whereas the highest degrees of alignment for iodobenzene and for methyliodide in helium droplets fall below the values obtained for isolated molecules. We believe this is due to the deviation from axial recoil in the Coulomb explosion process that probes the alignment of the molecules in the He droplets.}, language = {en} } @article{PentlehnerNielsenSlenczkaetal.2013, author = {Pentlehner, Dominik and Nielsen, Jens H. and Slenczka, Alkwin and M{\o}lmer, Klaus and Stapelfeldt, Henrik}, title = {Impulsive Laser Induced Alignment of Molecules Dissolved in Helium Nanodroplets}, series = {Physical Review Letters}, journal = {Physical Review Letters}, number = {110}, year = {2013}, abstract = {We show that a 450 fs nonresonant, moderately intense, linearly polarized laser pulse can induce field-free molecular axis alignment of methyliodide (CH3I) molecules dissolved in a helium nanodroplet. Time-resolved measurements reveal rotational dynamics much slower than that of isolated molecules and absence of the sharp transient alignment recurrences characteristic of gas phase molecules. Our results presage a range of new opportunities for exploring both molecular dynamics in a dissipative environment and the properties of He nanodroplets.}, language = {en} } @article{SlenczkaPentlehner2013, author = {Slenczka, Alkwin and Pentlehner, Dominik}, title = {Electronic spectroscopy of 9,10-dichloroanthracene inside helium droplets}, series = {The Journal of Chemical Physics}, journal = {The Journal of Chemical Physics}, number = {138}, year = {2013}, abstract = {The spectroscopy of molecules doped into superfluid helium droplets provides information on both, the dopant molecule and the helium environment. Electronic spectra of 9,10-dichloroanthracene in helium droplets are presented and compared with corresponding gas phase spectra to unravel the influence of the helium environment. The combined investigation of fluorescence excitation and dispersed emission provides information on dynamic processes in addition to energetic conditions. For vibronic states, the helium induced decay channels dominate over all intramolecular channels that contribute to the gas phase behavior. In addition to the triplet splitting caused by the Cl isotopes, a fine structure resolved for all transitions in the fluorescence excitation spectrum was found, which is the signature of microsolvation of this compound in helium droplets. This fine structure is identified as a single pure molecular transition accompanied by a sharply structured phonon wing. The corresponding fine structure measured for bare anthracene shows remarkable differences.}, language = {en} } @article{PentlehnerSlenczka2012, author = {Pentlehner, Dominik and Slenczka, Alkwin}, title = {Microsolvation of anthracene inside superfluid helium nanodroplets}, series = {Journal of Molecular Physics, Special Issue: Dudley Herschbach Festschrift}, journal = {Journal of Molecular Physics, Special Issue: Dudley Herschbach Festschrift}, number = {110}, year = {2012}, abstract = {This article reports on the microsolvation of anthracene in superfluid helium nanodroplets as revealed by electronic spectroscopy. Among the polyacene molecules benzene, naphthalene, anthracene, tetracene and pentacene only anthracene and tetracene have been found to exhibit multiplet splitting of the electronic and vibronic transitions which can not be explained by a rotational fine structure. The experimental approach for the investigation of the multiplet is the combined investigation of the fluorescence excitation spectrum and dispersed emission spectra. New experimental data are presented on the microsolvation of anthracene in helium droplets. A detailed analysis of the anthracene data will be contrasted to corresponding data on tetracene. These data together with those reported for benzene, naphthalene and pentacene might serve to test and develop theoretical models which are needed to understand microsolvation of single molecules in superfluid helium droplets.}, language = {en} } @article{PentlehnerRiechersVdovinetal.2011, author = {Pentlehner, Dominik and Riechers, R. and Vdovin, A. and P{\"o}tzl, G.M. and Slenczka, A.}, title = {Electronic spectroscopy of molecules in superfluid helium nanodroplets: an excellent sensor for intramolecular charge redistribution}, series = {The Journal of Physical Chemistry, Special Issue: J. Peter Toennies Festschrift}, journal = {The Journal of Physical Chemistry, Special Issue: J. Peter Toennies Festschrift}, number = {115}, year = {2011}, abstract = {Electronic spectra of molecules doped into superfluid 4He nanodroplets reveal important details of the microsolvation in superfluid helium. The vibrational fine structure in the electronic spectra of phthalocyanine derivatives and pyrromethene dye molecules doped into superfluid helium droplets have been investigated. Together with previous studies on anthracene derivatives [J. Chem. Phys.2010, 133, 114505] and 3-hydroxyflavone [J. Chem. Phys.2009, 131, 194307], the line shapes vary between two limiting cases, namely, sharp Lorentzians and nonresolved vibrational fine structure. All different spectral signatures are initiated by the same effect, namely, the change of the electron density distribution initiated by the electronic excitation. This change can be quantified by the difference of the electrostatic moments of the molecule in the electronic ground state and the corresponding Franck-Condon point in the excited state. According to the experimental data, electronic spectroscopy suffers from drastic line broadening when accompanied by significant changes of the charge distribution, in particular, changes of the dipole moment. Vice versa, the vibrational fine structure in electronic spectra of molecules doped into helium droplets is highly sensitive to changes of the electron density distribution.}, language = {en} } @article{StromeckFaderlPentlehnerKensyetal.2011, author = {Stromeck-Faderl, A. and Pentlehner, Dominik and Kensy, U. and Dick, B.}, title = {High-resolution electronic spectroscopy of the BODIPY chromophore in supersonic beam and superfluid helium droplets}, series = {CHEM-PHYS-CHEM, Special Issue: Laser Chemistry and Spectroscopy}, journal = {CHEM-PHYS-CHEM, Special Issue: Laser Chemistry and Spectroscopy}, number = {12}, year = {2011}, abstract = {We present the fluorescence excitation and dispersed emission spectra of the parent compound of the boron dipyrromethene (BODIPY) dye class measured in a supersonic beam and isolated in superfluid helium nanodroplets. The gas-phase spectrum of the isolated molecules displays many low-frequency transitions that are assigned to a symmetry-breaking mode with a strongly nonharmonic potential, presumably the out-of-plane wagging mode of the BF2 group. The data are in good agreement with transition energies and Franck-Condon factors calculated for a double minimum potential in the upper electronic state. The corresponding transitions do not appear in the helium droplet. This is explained with the quasi-rigid first layer of helium atoms attached to the dopant molecule by van der Waals forces. The spectral characteristics are those of a cyanine dye rather than that of an aromatic chromophore.}, language = {en} } @article{PentlehnerGreilDicketal.2010, author = {Pentlehner, Dominik and Greil, Ch. and Dick, B. and Slenczka, Alkwin}, title = {Line broadening in electronic spectra of anthracene derivatives inside superfluid helium nanodroplets}, series = {The Journal of Chemical Physics}, journal = {The Journal of Chemical Physics}, number = {133}, year = {2010}, abstract = {Electronic spectroscopy of molecules profits greatly from superfluid helium droplets serving as a gentle cryogenic matrix. Characteristic features of electronic spectra in helium droplets are a solvent shift, phonon wings, and in rare cases a splitting of zero phonon lines. For the majority of molecules investigated so far in helium droplets the vibrational fine structure in electronic spectra resembles what was observed in a supersonic jet. The electronic spectra of three methylated anthracene derivatives and one phenylated anthracene discussed in this paper reveal remarkable effects in the vibrational fine structure due to solvation in helium droplets. For all four compounds the vibrational frequencies were almost not affected by the helium environment. However, if the electronic excitation is accompanied by nuclear rearrangement, the spectra showed remarkable line broadening in helium droplets. This is the case for 2-methylanthracene and 9-phenylanthracene. The corresponding line shape was of Lorentzian type and, thus, attributed to damping of the excited system by the helium environment. According to the linewidth the damping time constant was determined to be about 0.3 ps in the case of 2-methylanthracene and 0.1 ps for 9-phenylanthracene.}, language = {en} } @article{LehnigPentlehnerVdovinetal.2009, author = {Lehnig, R. and Pentlehner, Dominik and Vdovin, A. and Dick, B. and Slenczka, Alkwin}, title = {Photochemistry of 3-hydroxyflavone inside superfluid helium nanodroplets}, series = {The Journal of Chemical Physics}, journal = {The Journal of Chemical Physics}, number = {131}, year = {2009}, abstract = {3-hydroxyflavone is a prototype system for excited state intramolecular proton transfer which is one step of a closed loop photocycle. It was intensively studied for the bare molecule and for the influence of solvents. In the present paper this photocycle is investigated for 3-hydroxyflavone and some hydrated complexes when doped into superfluid helium droplets by the combined measurement of fluorescence excitation spectra and dispersed emission spectra. Significant discrepancies in the proton transfer behavior to gas phase experiments provide evidence for the presence of different complex configurations of the hydrated complexes in helium droplets. Moreover, for bare 3-hydroxyflavone and its hydrated complexes the proton transfer appears to be promoted by the helium environment.}, language = {en} } @article{PentlehnerRiechersDicketal.2009, author = {Pentlehner, Dominik and Riechers, Ricarda and Dick, B. and Slenczka, Alkwin and Even, U. and Lavie, N. and Brown, R. and Luria, K.}, title = {Rapidly pulsed helium droplet source}, series = {Review of scientific instruments}, journal = {Review of scientific instruments}, number = {80}, year = {2009}, abstract = {A pulsed valve connected to a closed-cycle cryostat was optimized for producing helium droplets. The pulsed droplet beam appeared with a bimodal size distribution. The leading part of the pulse consists of droplets suitable for doping with molecules. The average size of this part can be varied between 104 and 106 helium atoms, and the width of the distribution is smaller as compared to a continuous-flow droplet source. The system has been tested in a single pulse mode and at repetition rates of up to 500 Hz with almost constant intensity. The droplet density was found to be increased by more than an order of magnitude as compared to a continuous-flow droplet source.}, language = {en} } @article{MakPentlehnerStichetal.2009, author = {Mak, C. S. K. and Pentlehner, Dominik and Stich, M. and Wolfbeis, O. and Chan, W. K. and Yersin, H.}, title = {Exceptional Oxygen Sensing Capabilities and Triplet State Properties of Ir(ppy-NPh2)3}, series = {Chemistry of Materials}, journal = {Chemistry of Materials}, number = {21}, year = {2009}, abstract = {Strong oxygen quenching following a Stern-Volmer behavior of Ir(ppy-NPh2)3 demonstrates the high technological potential for oxygen sensing applications. This compound exhibits a phosphorescence quantum yield of 70\% and an emission decay time of 4.3 μs in deaerated solution. The electronic structure of the emitting triplet, being responsible for these properties, is investigated.}, language = {en} } @article{PentlehnerGrauYersin2008, author = {Pentlehner, Dominik and Grau, I. and Yersin, H.}, title = {Triplet State Properties of [Os(phen)2dppene]2+ in different host materials and host to guest energy transfer in PVK}, series = {Chemical Physics Letters}, journal = {Chemical Physics Letters}, number = {455}, year = {2008}, abstract = {Emission properties of [Os(phen)2(dppene)]2+ were investigated from 1.4 to 300 K in ethanol, PMMA, and PVK, a matrix which is frequently applied in OLEDs. These data provide the zero-field splitting values of the emitting T1 state and the individual decay times of its substates. The T1 state is assigned to be largely of MLCT character. The splittings change only moderately due to variation of the matrix, whereas the individual decay times are substantially affected. Further, energy transfer from the triplet state of PVK to [Os(phen)2(dppene)]2+ was studied by applying time-resolved emission spectroscopy and is assigned to be dominantly of Dexter type.}, language = {en} } @book{PfauTichelmann2008, author = {Pfau, Jochen and Tichelmann, Karsten}, title = {Dry Construction: Principles, Details, Examples}, series = {DETAIL Practice, Edition Detail}, journal = {DETAIL Practice, Edition Detail}, publisher = {Birkh{\"a}user}, organization = {Institut f{\"u}r internationale Architektur-Dokumentation, M{\"u}nchen}, publisher = {Technische Hochschule Rosenheim}, year = {2008}, language = {en} } @inproceedings{HirschmuellerMartePravida2016, author = {Hirschm{\"u}ller, Sebastian and Marte, Roman and Pravida, Johann}, title = {Laminated veneer lumber poles for temporary soil nailing - investigation of material properties}, series = {Proceedings of the World Conference on Timber Engineering. World Conference on Timber Engineering. Vienna, 22.-25.08. Vienna}, booktitle = {Proceedings of the World Conference on Timber Engineering. World Conference on Timber Engineering. Vienna, 22.-25.08. Vienna}, editor = {Eberhardsteiner, Josef and Winter, Wolfgang and Fadai, A. and P{\"o}ll, Martha}, year = {2016}, abstract = {Within a current research project at Rosenheim University of Applied Sciences and Graz University of Technology the possibilities of using beech wood laminated veneer lumber poles as soil anchors for temporary soil nailing systems are investigated. Therefore tensile and bending properties of laminated veneers with high moisture and permanent cement contact concerning the influence of veneer bending rectangular to the fibre are determined. For investigation of material properties under different climate conditions tensile tests on small and faultless single beech wood veneers as well as tensile tests on 6 layered 3 mm samples and 9 layered 2 mm samples were carried out. Therefore all samples were stored in extreme climate conditions like high moisture content and permanent cement contact. Six layered samples with 3mm thick veneers show a slightly higher strength and stiffness under dry conditions as well as at a moisture content of the samples above fibre saturation. A strength reduction factor concerning temporary geotechnical applications is suggested which considers the influence of long term loading, veneer bending, water saturation and cement destruction on tensile properties of laminated veneer lumber poles.}, 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} } @inproceedings{HirschmuellerPravidaMarteetal.2016, author = {Hirschm{\"u}ller, Sebastian and Pravida, Johann and Marte, Roman and Flach, Michael}, title = {Laminated veneer lumber poles for use in temporary soil nailing. Investigation of adhesive properties.}, series = {Holzbau Forschung und Praxis. 6. Doktorandenkolloqium 2016}, booktitle = {Holzbau Forschung und Praxis. 6. Doktorandenkolloqium 2016}, editor = {Universit{\"a}t Stuttgart,}, year = {2016}, abstract = {Within a current research-project the possibility of using laminated veneer lumber beech wood poles as temporary soil anchors in foundation engineering is investigated. Within this project adhesive properties of laminated veneer lumber beech wood poles are determined. For use in temporary ground applications the influence of veneer bending, veneer thickness and intensive cement contact is concerned. As standard version two different adhesive systemsmelamine formaldehyde resin (MUF) and a 1-component polyurethane adhesive (PUR) were investigated and compared. Melamine formaldehyde resin glued samples with 3 mm thick veneers and 1.0N/mm² press force show a higher tensile shear strength but also a higher adhesive failure percentage than polyurethane glued samples. In case of melamine formaldehyde resins the closed time has a great influence on bond line quality. A long closed time reveals a low penetration of adhesive in the cells and a low embedding on the wood surface. For curved structures best results were achieved with a bonding pressure of 1.0 N/mm². A significant difference in strength between the concerned MUF and PUR adhesive system was not recognized.}, 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: bonding performance of curved structures in a high-alkaline environment}, series = {Wood Science and Technology}, volume = {52}, journal = {Wood Science and Technology}, number = {5}, editor = {Springer,}, pages = {1289 -- 1311}, year = {2018}, abstract = {Circular hollow sections of beech-laminated veneer lumber (LVL) for the use as temporary geotechnical soil nailing systems are currently being developed. Due to their permanent subsoil cement embedment, investigations of the bond line quality of the timber sections are essential. This paper presents the bonding properties of flat and curved beech LVL after cyclic conditioning in a water-cement grout solution aimed at inducing short- and long-term alkaline attack of the timber. In total, 409 and 69 samples were tested in tensile shear tests after short-term and long-term conditioning, respectively. Three different adhesive systems, a one-component polyurethane adhesive, a melamine-urea-formaldehyde adhesive and a melamine-urea-formaldehyde adhesive modified by means of (polyvinyl)-acetate adhesive were investigated and compared. Short-term conditioning by submersion in boiling cement suspension was found to be a reliable method for testing the bonding performance rather than long-term conditioning. In the case of tensile shear tests of samples subjected to long-term treatment, wood material strength was the decisive criterion. Generally, tensile shear test samples of all investigated adhesives achieved reliable bonding for a pressing force up to 1.0 MPa. No relationship was recognised between the determined bonding failure and the wood properties tensile shear strength, wood failure percentage, fracture pattern and bulk density of veneers adjacent to the bond line. For the determination of the bond line integrity of curved veneer poles, it was necessary to test bonding quality in a combined test using curved and flat samples and to compare tensile shear strength with data determined on reference samples in the same veneer population without bond line.}, language = {en} } @phdthesis{Hirschmueller2019, author = {Hirschm{\"u}ller, Sebastian}, title = {Beech circular hollow laminated veneer lumber sections for temporary soil nailing applications}, school = {Technische Hochschule Rosenheim}, year = {2019}, abstract = {Beech Laminated Veneer Lumber (LVL) circular hollow sections for use as temporary geotechnical soil nailing systems are developed within this thesis. Due to their permanent subsoil cement embedment, combined with high water saturation and permanent loading, the timber sections will lose strength and stiffness over time. 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 soil nails by 80\%. In addition to the determination of material properties on small, clear specimens and full-sized cross-sections, an 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 standardised testing and conditioning methods for examining LVL surface bond line quality. Standardised test methods had to be modified to determine bonding parameters for the circular, hollow LVL sections. As cement grout ensures the bond between the wooden nails and soil for the mobilisation of a soil reinforcement effect, a reliable connection between cement and wood is required. However, soluble wood constituents may inhibit cement hydration in the contact surface between the timber nails and cement. Pull-off tests on clear LVL specimens with different cement and wood surface modifications as well as the results of large-scale push-out tests are therefore presented. But to permanently ensure the contact between the wood and cement, a high degree of saturation above wood fibre saturation is necessary to keep the hollow sections in a swollen state without moisture-dependent wood shrinking. As no publications of wood moisture development in subsoil were available, long-term tests were performed, measuring the moisture content of subsoil-stored LVL in dependence on the soil moisture content, the suction and the precipitation during a time span of one year. Besides a negative cement influence on the material strength, a positive effect of cement coating on subsoil fungal destruction was realised, resulting in a significantly increased lifetime of cement-coated wood compared to uncoated wood. For temporary soil nailing applications, fungal wood deterioration was found to be of minor importance. But the reduced material strength due to a severe alkaline attack of wood demands a re-consideration of current soil nailing design methods, usually based on a mechanical limit equilibrium analysis of a rigid body motion where just tensile forces of the reinforcement elements are considered, and accompanying forces like bending moments and shear forces are neglected. Distributed fibre optic strain measurements of a steel-reinforced soil nail wall during a time span of six weeks reveal considerable nail curvatures, which are negligible in the case of ductile soil nails with low diameters, but are a significant factor for beech circular hollow laminated veneer lumber sections of larger diameters and brittle material behaviour.}, 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} } @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} } @inproceedings{MonsbergerLienhartMarteetal.2018, author = {Monsberger, Christoph and Lienhart, Werner and Marte, Roman and Hirschm{\"u}ller, Sebastian}, title = {Monitoring of soil nailed slope stabilizations using distributed fiber optic sensing}, series = {Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2018}, volume = {10598}, booktitle = {Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2018}, editor = {Sohn, Hoon}, doi = {10.1117/12.2296674}, year = {2018}, abstract = {Soil nailing systems are a common way to stabilize slopes and construction pits. Their design is usually based on the mechanical equilibrium of a rigid body motion and therefore, only tensile stresses are considered and accompanying forces like bending (shear stresses) in the soil nails are neglected. Continuous strain measurements along nails could verify this assumption, but may not be performed using conventional sensing technologies. This paper reports about monitoring of a soil nailed slope stabilization using distributed fiber optic sensing. Soil nails in different anchoring horizons were instrumented and autonomously monitored over several weeks, in which the construction pit was excavated continuously. After the excavation, the final load bearing capacity of one selected nail was determined within a classical geotechnical load test. In addition to the field measurements, the bending behavior of the instrumented nail system was analyzed under laboratory conditions. The presented studies demonstrate the high potential of distributed fiber optic sensing systems and their capability to extend traditional measurement methods in foundation engineering applications.}, language = {en} } @article{Eierle2009, author = {Eierle, Benno}, title = {Structural Calculations for Windows made easy}, series = {t{\"u}r-tor-fenster-report}, journal = {t{\"u}r-tor-fenster-report}, number = {2/2009}, publisher = {VFZ Verlag}, address = {Dortmund}, year = {2009}, language = {en} } @inproceedings{SchefflerGehdeSpaethetal.2017, author = {Scheffler, T. and Gehde, M. and Sp{\"a}th, M. and Karlinger, Peter}, title = {Determination of the flow and curing behavior of highly filled phenolic injection molding compounds by means of spiral mold}, series = {PPS Chemnitz}, booktitle = {PPS Chemnitz}, year = {2017}, language = {en} } @techreport{KarlingerMercadoColmeneroRubioParamioetal.2017, author = {Karlinger, Peter and Mercado-Colmenero, Jorge Manuel and Rubio-Paramio, Miguel Angel and Martin-Do{\~n}ate, Cristina}, title = {A new procedure for calculating cycle time in injection molding based on plastic part geometry recognition}, year = {2017}, language = {en} } @article{EierleKrewinkel2013, author = {Eierle, Benno and Krewinkel, K.}, title = {Safety barriers made of glass - evidence by calculation rather than testing?}, series = {t{\"u}r-tor-fenster report}, journal = {t{\"u}r-tor-fenster report}, number = {5/2013}, publisher = {VFZ Verlag}, address = {Dortmund}, pages = {10 -- 14}, year = {2013}, language = {en} } @inproceedings{VersenKipfelsberger2014, author = {Versen, Martin and Kipfelsberger, S.}, title = {Introduction to microcomputer technology with the MSP430 Launch Pad in remote labs}, series = {Global Engineering Education Conference (EDUCON), 2014 IEEE}, booktitle = {Global Engineering Education Conference (EDUCON), 2014 IEEE}, year = {2014}, abstract = {Texas Instruments' MSP430 Launch Pad is used as a key component for remote labs that complement an introduction course to microcomputer technology in the bachelor program Mechatronic at the University of Applied Sciences in Rosenheim. The remote labs use breakout boards and include a timer experiment with generation of pulse width modulation signals, I2C communication and analog to digital conversion.}, language = {en} } @inproceedings{VersenBernhardtHeigletal.2012, author = {Versen, Martin and Bernhardt, and Heigl, M. and Viehhauser, P. and Zentgraf, P.}, title = {System for real-time data acquisition and processing on a hail-fighter aeroplane}, series = {Proceedings of the 5th European DSP Education and Research Conference}, booktitle = {Proceedings of the 5th European DSP Education and Research Conference}, year = {2012}, abstract = {The System HAILsens implements a device for Real-Time sensor data processing, running on a Texas Instruments Concerto M3 core. An I2C interface is used for sensor communications. Ethernet with UDP on a custom developed three layered frame organisation of sensor data serves as a link to the main system on board of an aeroplane. For backing up the acquired data, all frames are locally stored on an SD Card. To have the possibility of easily checking the current system status, an LCD module and a push-button provide a minimal user interface.}, language = {en} } @incollection{Versen2011, author = {Versen, Martin}, title = {DRAM Failure Analysis and Defect Localization Techniques, Microelectronics Failure Analysis}, series = {Desk Reference Sixth Edition}, booktitle = {Desk Reference Sixth Edition}, publisher = {ASM International}, address = {Ohio}, publisher = {Technische Hochschule Rosenheim}, year = {2011}, abstract = {Comprehensive guide to the process and test methods used for electronic device failure analysis. Contains dozens of articles—contributed by industry experts—covering a wide range of topics involving the failure analysis of microelectronics. It places the most important and up-to-date information on this subject at your fingertips.  Topic coverage includes:  Failure Analysis Process Flow Failure Verification  Failure Modes and Failure Classification  Special Devices (MEMS, Optoelectronics, Passives)  Fault Localization Techniques: Package Level (NDT)  Die Level (Depackaging, Photon Emission, Microthermography, Laser-Based Methods, Particle Beam Methods)  Deprocessing \& Imaging Techniques: Deprocessing  General Imaging Techniques  Local Deprocessing \& Imaging  Circuit Edit and Design Modification  Material Analysis Techniques  Reference Information: Important Topics for Semiconductor Devices  Failure Analysis Techniques Roadmap  Failure Analysis Operations and Management  Appendices: Failure Analysis Terms, Definitions, and Acronyms  Industry Standards}, language = {en} } @inproceedings{VersenShankarEnimidisettyetal.2011, author = {Versen, Martin and Shankar, S. and Enimidisetty, S. and Bernhardt, A. and Srinivasan, B.}, title = {Setup for Locating PV-Cell Surface Defects Through ISC Measurements}, series = {Proceedings of the 37th ISTFA 2011}, booktitle = {Proceedings of the 37th ISTFA 2011}, year = {2011}, language = {en} } @inproceedings{Versen2011, author = {Versen, Martin}, title = {Worst Case Test Conditions for Defect Localization in DRAM Devices}, series = {Microelectronics Seminar of the ISTFA 2011}, booktitle = {Microelectronics Seminar of the ISTFA 2011}, year = {2011}, language = {en} } @inproceedings{WittmannHaglKennel2016, author = {Wittmann, Josef and Hagl, Rainer and Kennel, Ralph}, title = {Influence of Position Measuring Errors on Speed Ripple in Servo Drives}, series = {2016 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM, Capri, Italy}, booktitle = {2016 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM, Capri, Italy}, year = {2016}, abstract = {Position measuring devices with sinusoidal measuring signals are widely used in position-controlled servo drives in industrial automation, e.g., for machine tools or semiconductor production machines. Usually, the feedback signal for the speed or velocity controller is calculated from the measured position. Therefore, position measuring errors affect these control loops. This study presents an analytic error model that considers non-ideal sinusoidal measuring signals with basic deviations (amplitude differences, offset errors, and phase shift) as well as signal harmonics. The model was used to systematically investigate the influence of signal quality and the number of signal periods from position measuring devices on speed ripple, across a wide range of speeds. A test stand with a high-resolution reference angle measuring device was used to confirm the results.}, language = {en} } @inproceedings{WittmannHaglKennel2017, author = {Wittmann, Josef and Hagl, Rainer and Kennel, Ralph}, title = {Hybrid Current and Acceleration Control of Servo Drives}, series = {PCIM Europe 2017 - International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, N{\"u}rnberg}, booktitle = {PCIM Europe 2017 - International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, N{\"u}rnberg}, year = {2017}, abstract = {A hybrid current and acceleration control is presented and shown to improve the load disturbance behavior of servo drives significantly without additional sensor effort. The feedback signal of the acceleration control loop is calculated from the position data of the motor encoder. Hence, position measuring errors influence this control loop and lead to speed ripple. Therefore, the presented design of the acceleration control loop considers both load sensitivity and position measuring errors.}, language = {en} } @inproceedings{StubenrauchWittmannKiermayeretal.2017, author = {Stubenrauch, Franz and Wittmann, Josef and Kiermayer, Alexander and Seliger, Norbert and Hagl, Rainer and Schmitt-Landsiedel, Doris and Kennel, Ralph}, title = {FPGA-based High Dynamic Servo Drive Control with a 200kHz Gallium Nitride Inverter}, series = {2017 19th European Conference on Power Electronics and Applications (EPE'17 ECCE Europe), Warsaw, Poland}, booktitle = {2017 19th European Conference on Power Electronics and Applications (EPE'17 ECCE Europe), Warsaw, Poland}, year = {2017}, abstract = {Increased productivity in industrial processes can be achieved by dynamic and accurate positioning of servo drives. Therefore, improvement of servo drive dynamics using latest technologies in the key components such as inverter, control system and position measuring device are investigated. Using Gallium Nitride (GaN) or Silicon Carbide (SiC) semiconductors for motor inverters enables energy efficient operation up to pulse width modulation (PWM) frequencies of 500 kHz. This allows motor filters with small component sizes. As a result, high motor efficiency, low torque ripple, high control bandwidth and almost ideal sinusoidal output voltages are achieved. Experiments on a 200 kHz Gallium Nitride inverter with sine wave motor filter show a current control loop bandwidth of 3.2 kHz and almost ideal sinusoidal phase voltages. The achieved bandwidths of the speed and position control loops are 318 Hz and 106 Hz, respectively.}, language = {en} } @article{VersenErnstGulati2017, author = {Versen, Martin and Ernst, W. and Gulati, P.}, title = {A row hammer pattern analysis of DDR2 SDRAM}, series = {Microelectronics Reliability}, volume = {76-77}, journal = {Microelectronics Reliability}, pages = {64 -- 67}, year = {2017}, abstract = {A DDR2 SDRAM test setup implemented on the Griffin III ATE test system from HILEVEL Technologies is used to analyse the row hammer bug. Row hammer pattern experiments are compared to standard retention tests. The analysis confirms that the row hammer effect is caused by a charge excitation process depending on the number of stress activation cycles. The stress has to occur in the local neighborhood of the cells under test. Shallow impurity levels support the responsible charge carrier transport process in the used DDR2 SDRAM technology}, language = {en} } @inproceedings{VersenKipfelsbergerSoekmen2016, author = {Versen, Martin and Kipfelsberger, F. and Soekmen, F.}, title = {Model-Based Reference Design Projects with MathWorks' HDL Workflow Advisor for Custom-Specific Electronics with the Zedboard}, series = {ANALOG 2016; 15. ITG/GMM-Symposium, Bremen, Germany}, booktitle = {ANALOG 2016; 15. ITG/GMM-Symposium, Bremen, Germany}, year = {2016}, abstract = {Reference design projects are implemented to the Xilinx Zynq on the Zedboard which is extended by user defined electronic hardware connected through the Zedboard's FMC (FPGA Mezzanine Card) connector. The implementation method with HDL Workflow Advisor includes constraint definitions for modified reference design projects for use with digital input and outputs and Zynq's XADC (Analog-Digital converter) which is characterized and compared to its data sheet. The bandwidth of the Zynq's internal AXI (Advanced eXtensible Interface) bus connected to the Simulink host PC is determined.}, language = {en} } @article{VersenErnstGulatietal.2015, author = {Versen, Martin and Ernst, W. and Gulati, P. and Singh, G.}, title = {Test setup for reliability studies of DDR2 SDRAM}, series = {Microelectronics Reliability}, journal = {Microelectronics Reliability}, year = {2015}, abstract = {A DDR2 DRAM test setup is developed and implemented on the Griffin III ATE test system from HILEVEL Technologies. The test system provides a raw platform for performing various mixed signal and digital tests. In order to configure patterns easily in a vector format, a software platform is developed to manage test patterns according to the user's analysis needs. As examples, retention test patterns with disabled self-refresh are applied to 2 Gbit DDR2 SDRAM of two different DRAM vendors. The devices are characterized in respect to their intrinsic leakage and data retention behavior under the influence of stress conditions such as temperature or access algorithm. The tests are automated and test data is logged for an off-line data analysis. Data is recorded before and after solder simulation steps in order to observe a retention time degradation.}, language = {en} } @inproceedings{VersenHayn2014, author = {Versen, Martin and Hayn, M.}, title = {Introduction to Verification and Test Using a 4-Bit Arithmetic Logic Unit Including a Failure Module in a Xilinx XC9572XL CPLD}, series = {Proceedings of the 40th ISTFA 2014}, booktitle = {Proceedings of the 40th ISTFA 2014}, year = {2014}, language = {en} } @misc{AuerHusmann2015, author = {Auer, Veronika and Husmann, Kai}, title = {Perspectives of a future-proof logistics applied to the natural raw material supply in the Cluster Region (Plan C). Postersession.}, editor = {Auer, Veronika}, year = {2015}, language = {en} } @inproceedings{AuerZscheile2017, author = {Auer, Veronika and Zscheile, Mathias}, title = {Designing the beech wood supply chain. Vortrag auf der BioEconomy Conference 11. Mai 2017 in Halle/Saale.}, series = {BioEconomy Conference. Sciences Campus Halle, BioEconomy Cluster. Halle/Saale, 11.05.2017}, booktitle = {BioEconomy Conference. Sciences Campus Halle, BioEconomy Cluster. Halle/Saale, 11.05.2017}, year = {2017}, abstract = {Bio-based products show a great potential to reduce the dependence on fossil resources. Germany currently has a forerunner role in the EU, using biomass as the same resource base for material and energetic utilisation. Beech wood is hyped in both ways: In material usage directly e.g., in the building sector to balance the possible scarcity of soft wood in the future, as well as indirectly as a feedstock for biorefineries, representing a long-term alternative to the fossil-based industry, and secondly, as energetic use due to its excellent burning quality. The BIOECONOMY CLUSTER sees itself as an actor in a difficult tension field within implementation of the wood-based Bioeconomy. With a total stocking volume of about 635 million m3, beech is the most abundant hardwood tree species in Germany. Nevertheless, beech wood-based biorefineries compete in a difficile tension field. One crucial factor is the reliable supply of raw materials - a consistent biomass quality, season-independent availability and efficient logistics of the raw material. However, the production processes are technically feasible; thus, finally, there is no guarantee for selling the bio-based products to the obtained price. How to overcome the strong tension field in the beech-based Bioeconomy? Different selected examples show possible approaches. To manage the wood-based Bioeconomy and the beech wood supply chain effectively, the influencing of factors and the managing of the same is crucial.}, language = {en} } @inproceedings{AuerZscheileEngleretal.2016, author = {Auer, Veronika and Zscheile, Matthias and Engler, Benjamin and Haller, Peer and Hartig, Jens and Wehsener, J{\"o}rg and Husmann, Kai and Erler, J{\"o}rn and Thole, Volker and Schulz, Tino and Hesse, Elfi and R{\"u}ther, Norbert and Himsel, Alexandra}, title = {BIOECONOMY CLUSTER: resource efficient creation of value from beech wood to bio-based building materials.}, series = {WCTE 2016. CD-ROM Proceedings of the World Conference on Timber Engineering.}, booktitle = {WCTE 2016. CD-ROM Proceedings of the World Conference on Timber Engineering.}, editor = {Eberhardsteiner, J. and Winter, W. and Fadai, A. and P{\"o}ll, M.}, year = {2016}, language = {en} } @inproceedings{RiederKrommesLang2017, author = {Rieder, Rosina and Krommes, Sandra and Lang, Werner}, title = {Criticality assessment of indium for thin-film photovoltaics in the context of sustainability goals for the German housing sector}, series = {PROCEEDINGS of 33rd PLEA International Conference}, booktitle = {PROCEEDINGS of 33rd PLEA International Conference}, editor = {Brotas, Luisa and Roaf, Susan and Nicol, Fergus}, publisher = {NCEUB}, address = {Edinburgh}, isbn = {978-0-9928957-5-4}, pages = {3692 -- 3698}, year = {2017}, abstract = {In countries with large import dependencies, several studies on strategically important metals have classified raw materials as being critical by combining supply and vulnerability risks. In case of availability, the most critical raw materials are metallic ores and industrial minerals. Within the scope of developing resource efficient buildings, innovative building technologies, such as renewable energy systems, are becoming increasingly integral parts of buildings. Since critical raw materials are essential components in building technologies, they will also play an important role in the housing sector. In this context, it is crucial to consider how sustainability goals in the housing sector are affected by raw material criticality. This paper addresses supply and vulnerability risks of indium, which is contained in thin-film photovoltaics, in order to identify their impacts on future developments in the housing sector. Raw material availability is significantly influenced by the demand and supply of raw materials. To implement risk factors for a criticality assessment in sector-specific material flows, their impacts are analysed and modelled using a dynamic, macro-economic approach. Assuming different energy scenarios in the German housing sector up to 2050, the model reveals the raw material criticality by pointing out supply risks in order to derive recommendations.}, language = {en} } @inproceedings{Zentgraf2017, author = {Zentgraf, Peter}, title = {ANALYTICAL ATTITUDE DETERMINATION FROM A SPECIFIC RATE PROFILE}, series = {40th ANNUAL AAS GUIDANCE AND CONTROL CONFERENCE, Breckenridge, Colorado, USA}, booktitle = {40th ANNUAL AAS GUIDANCE AND CONTROL CONFERENCE, Breckenridge, Colorado, USA}, year = {2017}, abstract = {The problem dealt with in this paper is the analytical determination of the attitude of a rigid body which undergoes a given rate profile. Usually the attitude is determined by solving the kinematic differential equation numerically. For long lasting movements the outcome can cost computation time plus encountered losses in accuracy, which can be disturbing especially in optimization problems. This contribution solves the kinematic differential equation for certain rate profiles exactly and compares the results in accuracy and computation time with the standard procedures.}, language = {en} } @inproceedings{ZentgrafBergeChassetetal.2010, author = {Zentgraf, Peter and Berge, S. and Chasset, C. and Filippi, H. and Gottzein, E. and Guti{\´e}rrez-Ca{\~n}as, I. and Hartrampf, M. and Krauss, P. A. and Kuehl, C. and L{\"u}bke- Ossenbeck, B. and Mittnacht, M. and Montenbruck, O. and M{\"u}ller, C. and Rueda Boldo, P. and Truffi, A.}, title = {PREPARING THE GPS-EXPERIMENT FOR THE SMALL GEO MISSION}, series = {33rd ANNUAL AAS GUIDANCE AND CONTROL CONFERENCE}, booktitle = {33rd ANNUAL AAS GUIDANCE AND CONTROL CONFERENCE}, editor = {American Astronautical Society,}, year = {2010}, abstract = {This paper deals with the preparation of the Small GEO mission and the accommodation of a GPS receiver as an experiment. The expected benefits of using the GPS receiver for Small GEO are explained. The feasibility of using GPS for position determination is investigated by simulation using a MosaicGNSS receiver, which was stimulated by a Spirent RF signal generator. A procedure, how to evaluate flight data on ground is outlined. Success criteria of the experiment and the minimal size of the downlink stream required and reserved for the receiver TM are presented.}, language = {en} } @misc{ZentgrafErb2009, author = {Zentgraf, Peter and Erb, S.}, title = {IMPACT OF ELECTRIC PROPULSION UNCERTAINTY ON ORBIT PREDICTION}, editor = {Zentgraf, Peter}, year = {2009}, abstract = {This paper analyses the achievable performance of the orbit prediction for a geostationary satellite using clusters of electrical propulsion (EP) thrusters for station-keeping and a star tracker based attitude control system. The challenge in the orbit prediction is that the real electrical propulsion thrust is known with limited accuracy only. In combination with thrust pointing errors, these inaccuracies can accumulate to large orbit position errors during long low thrust burn arcs. The discrepancy between real and predicted satellite position is determined in terms of probability and as a worst case scenario.}, language = {en} } @inproceedings{ZentgrafReggio2009, author = {Zentgraf, Peter and Reggio, D.}, title = {MAGNETIC RATE DAMPING FOR SATELLITES IN LEO}, series = {32nd ANNUAL AAS GUIDANCE AND CONTROL CONFERENCE}, booktitle = {32nd ANNUAL AAS GUIDANCE AND CONTROL CONFERENCE}, year = {2009}, abstract = {This article deals with the topic of damping the rates of a satellite after separation from the launcher by sensing the rates with magnetometers or gyroscopes and actually damping it with torquerods or thrusters. In literature problems of this kind are treated by linearization which is not adequate here due to the high nonlinearity of the problem caused by the high gyroscopic torque. This paper addresses the observability and controllability of the rate dynamics for symmetric satellite bodies. Furthermore, robust stability of any bodies is investigated by means of the Krasovskii-LaSalle principle which is a variant of Ljapunov's Second Method. It is found that - apart from one exception - the system is robustly stable for certain conditions depending only on the gain matrix and not depending on the orbit, moments of inertia or initial conditions. The exception is that of the intuitive case of an equator type orbit, in which the satellite rotates around the magnetic field lines, in this case the satellite's rate cannot be damped. Several design configurations are analysed with respect to their performance and cost: Rate damping with magnetometers or gyroscopes as sensors, and torquerods and thrusters as actuators. The results are evaluated with respect to the time to reach the desired rate, the propellant and the power equivalent battery mass used. The goal is to use the results to allow an AOCS equipment and architecture trade-off at an early project phase. The design of the rate damping control of the SWARM project is presented as an example and demonstrated with simulations.}, language = {en} }