Ein Beitrag zur Auslegung tragender Klebverbindungen im Fassadenbau

Die Dimensionierung von tragenden Klebverbindungen ist normativ nicht geregelt. Dies erschwert die Anwendung dieser Fügetechnologie. In der vorliegenden Dissertation werden Untersuchungen zur Auslegung tragender Klebverbindungen im Glas- und Fassadenbau beschrieben. Das wesentliche Kernelement ist hierbei die Analyse des zeit- und temperaturabhängigen Tragverhaltens der Klebverbindungen unter Berücksichtigung der Einwirkungsvorgänge. Es wird zunächst der Stand der Technik mit dem Fokus auf das Trag- und Versagensverhalten von Klebverbindungen aufgearbeitet. Das mechanische Verhalten der Klebschicht wird anhand relevanter theoretischer Grundlagen der Polymermechanik sowie der Werkstofftechnik erläutert. In Ergänzung werden Methoden zur Beschreibung des Werkstoffverhaltens dargelegt und Vorgehensweisen zur Versagensprognose sowie Dimensionierung aufgeführt. Auf dieser Basis werden ausgewählte klimatische Einwirkungsvorgänge analysiert. Dies geschieht zunächst durch systematische Analyse des Temperaturverlaufs in geklebten Verbindungen durch Freiluftmessungen. Hierbei werden Temperaturen in Klebschichten unter Einwirkung solarer Strahlung sowie der Lufttemperatur messtechnisch erfasst und analysiert. Anhand der Erkenntnisse werden Rückschlüsse sowohl auf auftretende Temperaturänderungsraten als auch auf die Wirkungsdauer ermittelt. Auf Basis dieser Ergebnisse wird anhand historischer Wetterdaten des Deutschen Wetterdienstes die Wirkungsdauer klimatischer Einwirkungsgrößen in Abhängigkeit von der Lasthöhe analysiert und in Form von Lastkollektiven beschrieben. An drei verschiedenen Klebstoffen werden umfangreiche experimentelle Untersuchungen durchgeführt. Hierzu werden diese zunächst mit Hilfe verschiedener Experimente werkstofftechnisch charakterisiert. In der anschließenden Hauptversuchsreihe wird das Verhalten von querdehnbehinderten Klebverbindungen unter Zugbeanspruchung untersucht. Durch die Verwendung verschiedener Querschnittsvariationen (Breite-/Höhe-Verhältnisse) wird der Einfluss der Geometrie auf das Trag- und Versagensverhalten untersucht. Die Experimente werden unter Einfluss verschiedener Parameter (Temperaturen, Dehnrate, Feuchte) durchgeführt. Aufbauend auf diesen Erkenntnissen wird das Tragverhalten der linienförmigen Klebverbindung analytisch wie auch numerisch untersucht. Zunächst werden sowohl analytisch als auch numerisch die Beanspruchungszustände im querdehnbehinderten Zugexperiment analysiert. Auf dieser Grundlage wird ein analytisches Modell zur Prognose des geometrieabhängigen Eintretens von Kavitationseffekten unter Zugbeanspruchung hergeleitet. Die Prognosefähigkeit dieses Modells wird anhand der durchgeführten experimentellen Untersuchungen validiert. Ferner wird der Einfluss von Zeit und Temperatur auf das Eintreten dieser Kavitationseffekte betrachtet. Hierzu wird durch die Anwendbarkeit der Zeit-Temperatur-Verschiebung gezeigt, dass verschiedene Experimente und Probenformen den identischen Relaxationsmechanismen folgen. Anhand eines abschließenden Berechnungsbeispiels unter Anwendung eines zuvor zeit-und temperaturabhängig kalibrierten visko-elastischen Werkstoffmodells wird der Einfluss der Temperatur auf den Ausnutzungsgrad eines Fugenabschnittes unter Windbelastung aufgezeigt

Ein Beitrag zur Auslegung tragender Klebverbindungen im Fassadenbau

This work describes investigations into the design of load-bearing bonded joints facade construction. The core element is the analysis of the time- and temperature-dependent load-bearing behavior of bonded joints. For this purpose, actions are analyzed, the time- and temperature-dependent behavior of various adhesives is investigated experimentally and theoretical considerations of the load-bearing behavior are carried out

IRGM variants and susceptibility to inflammatory bowel disease in the German population.

Genome-wide association studies identified the autophagy gene IRGM to be strongly associated with Crohn's disease (CD) but its impact in ulcerative colitis (UC), its phenotypic effects and potential epistatic interactions with other IBD susceptibility genes are less clear which we therefore analyzed in this study. Genomic DNA from 2060 individuals including 817 CD patients, 283 UC patients, and 961 healthy, unrelated controls (all of Caucasian origin) was analyzed for six IRGM single nucleotide polymorphisms (SNPs) (rs13371189, rs10065172 = p.Leu105Leu, rs4958847, rs1000113, rs11747270, rs931058). In all patients, a detailed genotype-phenotype analysis and testing for epistasis with the three major CD susceptibility genes NOD2, IL23R and ATG16L1 were performed. Our analysis revealed an association of the IRGM SNPs rs13371189 (p = 0.02, OR 1.31 [95% CI 1.05-1.65]), rs10065172 = p.Leu105Leu (p = 0.016, OR 1.33 [95% CI 1.06-1.66]) and rs1000113 (p = 0.047, OR 1.27 [95% CI 1.01-1.61]) with CD susceptibility. There was linkage disequilibrium between these three IRGM SNPs. In UC, several IRGM haplotypes were weakly associated with UC susceptibility (p<0.05). Genotype-phenotype analysis revealed no significant associations with a specific IBD phenotype or ileal CD involvement. There was evidence for weak gene-gene-interaction between several SNPs of the autophagy genes IRGM and ATG16L1 (p<0.05), which, however, did not remain significant after Bonferroni correction. Our results confirm IRGM as susceptibility gene for CD in the German population, supporting a role for the autophagy genes IRGM and ATG16L1 in the pathogenesis of CD

Modelling small block aperture in an in-house developed GPU-accelerated Monte Carlo-based dose engine for pencil beam scanning proton therapy

Purpose: To enhance an in-house graphic-processing-unit (GPU) accelerated virtual particle (VP)-based Monte Carlo (MC) proton dose engine (VPMC) to model aperture blocks in both dose calculation and optimization for pencil beam scanning proton therapy (PBSPT)-based stereotactic radiosurgery (SRS). Methods and Materials: A block aperture module was integrated into VPMC. VPMC was validated by an opensource code, MCsquare, in eight water phantom simulations with 3cm thick brass apertures: four were with aperture openings of 1, 2, 3, and 4cm without a range shifter, while the other four were with same aperture opening configurations with a range shifter of 45mm water equivalent thickness. VPMC was benchmarked with MCsquare and RayStation MC for 10 patients with small targets (average volume 8.4 cc). Finally, 3 patients were selected for robust optimization with aperture blocks using VPMC. Results: In the water phantoms, 3D gamma passing rate (2%/2mm/10%) between VPMC and MCsquare were 99.71$\pm$0.23%. In the patient geometries, 3D gamma passing rates (3%/2mm/10%) between VPMC/MCsquare and RayStation MC were 97.79$\pm$2.21%/97.78$\pm$1.97%, respectively. The calculation time was greatly decreased from 112.45$\pm$114.08 seconds (MCsquare) to 8.20$\pm$6.42 seconds (VPMC), both having statistical uncertainties of about 0.5%. The robustly optimized plans met all the dose-volume-constraints (DVCs) for the targets and OARs per our institutional protocols. The mean calculation time for 13 influence matrices in robust optimization by VPMC was 41.6 seconds. Conclusion: VPMC has been successfully enhanced to model aperture blocks in dose calculation and optimization for the PBSPT-based SRS.Comment: 3 tables, 3 figure

Clinical commissioning of intensity-modulated proton therapy systems: Report of AAPM Task Group 185

Proton therapy is an expanding radiotherapy modality in the United States and worldwide. With the number of proton therapy centers treating patients increasing, so does the need for consistent, high-quality clinical commissioning practices. Clinical commissioning encompasses the entire proton therapy system\u27s multiple components, including the treatment delivery system, the patient positioning system, and the image-guided radiotherapy components. Also included in the commissioning process are the x-ray computed tomography scanner calibration for proton stopping power, the radiotherapy treatment planning system, and corresponding portions of the treatment management system. This commissioning report focuses exclusively on intensity-modulated scanning systems, presenting details of how to perform the commissioning of the proton therapy and ancillary systems, including the required proton beam measurements, treatment planning system dose modeling, and the equipment needed

Beam mask and sliding window-facilitated deep learning-based accurate and efficient dose prediction for pencil beam scanning proton therapy

Purpose: To develop a DL-based PBSPT dose prediction workflow with high accuracy and balanced complexity to support on-line adaptive proton therapy clinical decision and subsequent replanning. Methods: PBSPT plans of 103 prostate cancer patients and 83 lung cancer patients previously treated at our institution were included in the study, each with CTs, structure sets, and plan doses calculated by the in-house developed Monte-Carlo dose engine. For the ablation study, we designed three experiments corresponding to the following three methods: 1) Experiment 1, the conventional region of interest (ROI) method. 2) Experiment 2, the beam mask (generated by raytracing of proton beams) method to improve proton dose prediction. 3) Experiment 3, the sliding window method for the model to focus on local details to further improve proton dose prediction. A fully connected 3D-Unet was adopted as the backbone. Dose volume histogram (DVH) indices, 3D Gamma passing rates, and dice coefficients for the structures enclosed by the iso-dose lines between the predicted and the ground truth doses were used as the evaluation metrics. The calculation time for each proton dose prediction was recorded to evaluate the method's efficiency. Results: Compared to the conventional ROI method, the beam mask method improved the agreement of DVH indices for both targets and OARs and the sliding window method further improved the agreement of the DVH indices. For the 3D Gamma passing rates in the target, OARs, and BODY (outside target and OARs), the beam mask method can improve the passing rates in these regions and the sliding window method further improved them. A similar trend was also observed for the dice coefficients. In fact, this trend was especially remarkable for relatively low prescription isodose lines. The dose predictions for all the testing cases were completed within 0.25s

Consensus Statement on Proton Therapy in Mesothelioma

Purpose: Radiation therapy for mesothelioma remains challenging, as normal tissue toxicity limits the amount of radiation that can be safely delivered to the pleural surfaces, especially radiation dose to the contralateral lung. The physical properties of proton therapy result in better sparing of normal tissues when treating the pleura, both in the postpneumonectomy setting and the lung-intact setting. Compared with photon radiation, there are dramatic reductions in dose to the contralateral lung, heart, liver, kidneys, and stomach. However, the tissue heterogeneity in the thorax, organ motion, and potential for changing anatomy during the treatment course all present challenges to optimal irradiation with protons. Methods: The clinical data underlying proton therapy in mesothelioma are reviewed here, including indications, advantages, and limitations. Results: The Particle Therapy Cooperative Group Thoracic Subcommittee task group provides specific guidelines for the use of proton therapy for mesothelioma. Conclusions: This consensus report can be used to guide clinical practice, insurance approval, and future research