Influence of the mix composition on the early-age autogenous deformations of the cement paste matrix of high-performance concrete

Bei Hochleistungsbetonen werden trotz der für Normalbetone üblichen Nachbehandlung häufig Schäden im jungen Alter in Form einer Mikrorissbildung beobachtet. Diese Mikrorisse, die insbesondere bei Zugabe von Mikrosilica auftreten, sind größtenteils auf das autogene Schwinden der Bindemittelmatrix zurückzuführen. Die autogenen Verformungen der Bindemittelmatrix eines Betons werden durch eine Vielzahl von Materialparametern beeinflusst und sind eng mit der Hydratation und der daraus resultierenden Selbstaustrocknung, aber auch mit den sich insbesondere im jungen Alter stark verändernden Gefügeeigenschaften verknüpft. Die Aussagekraft einfacher, auf empirischen Untersuchungen basierender Stoffmodelle, die ein „autogenes Schwindmaß“ vorhersagen sollen, ist jedoch begrenzt, da sie die Komplexität der hydratationsbedingten Vorgänge bei Hochleistungsbetonen im jungen Alter nur unzureichend abbilden. Für die Erweiterung des Kenntnisstands wurden in dieser Arbeit deshalb der Einfluss der Bestandteile und der Zusammensetzung der Bindemittelmatrix von Hochleistungsbetonen auf ihr autogenes Verformungsverhalten systematisch untersucht und kausale Zusammenhänge aufgezeigt. Hierfür wurden die gemessenen autogenen Verformungen sowohl mit der Hydratation als auch mit der sich entwickelnden Porenstruktur und den mechanischen Eigenschaften in Beziehung gesetzt. Es konnte damit gezeigt werden, dass das beobachtete autogene Schwindverhalten zumindest nach dem für Bindemittelleime mit niedrigen w/b-Werten typischen starken Anfangsschwinden mit der Selbstaustrocknung und den dadurch zu erwartenden Kapillarspannungen korreliert.High-performance concretes (HPC) show a higher proneness to early-age cracking than conventional concretes even when proper curing is applied. These micro cracks, which appear in particular when silica fume is added, are mainly attributed to the autogenous shrinkage of the cement paste matrix. The autogenous deformations of concrete are influenced by a multitude of material parameters. They are a direct consequence of the cement hydration and the subsequent self-desiccation as well as of the structural properties which are changing rapidly in the early ages. In the past empirical studies provided the basis for simple material models, which intend to predict an ôautogenous shrinkage valueö. The significance of such material models is limited since they do not reproduce adequately the complexity of the processes caused by cement hydration in early-age HPC. In order to extend the state of knowledge, in this thesis the influences of the mix constituents and the mix composition of the cement paste matrix of HPC on their autogenous deformation behaviour were systematically investigated and causal relations were pointed out. For this purpose the measured autogenous deformations were linked to the hydration as well as to the developing pore structure and the mechanical properties. It was demonstrated that the autogenous shrinkage occurring after the large initial shrinkage, which is observed typically with cement pastes with low water/binder ratios, correlates with the self-desiccation and the thereby expected capillary stresses

Optimizing parametrized quantum circuits via noise-induced breaking of symmetries

Very little is known about the cost landscape for parametrized Quantum Circuits (PQCs). Nevertheless, PQCs are employed in Quantum Neural Networks and Variational Quantum Algorithms, which may allow for near-term quantum advantage. Such applications require good optimizers to train PQCs. Recent works have focused on quantum-aware optimizers specifically tailored for PQCs. However, ignorance of the cost landscape could hinder progress towards such optimizers. In this work, we analytically prove two results for PQCs: (1) We find an exponentially large symmetry in PQCs, yielding an exponentially large degeneracy of the minima in the cost landscape. (2) We show that noise (specifically non-unital noise) can break these symmetries and lift the degeneracy of minima, making many of them local minima instead of global minima. Based on these results, we introduce an optimization method called Symmetry-based Minima Hopping (SYMH), which exploits the underlying symmetries in PQCs to hop between local minima in the cost landscape. The versatility of SYMH allows it to be combined with local optimizers (e.g., gradient descent) with minimal overhead. Our numerical simulations show that SYMH improves the overall optimizer performance.Comment: 11 + 5 pages, 10 figure

The Grism Lens-Amplified Survey from Space (GLASS) X. Sub-kpc resolution gas-phase metallicity maps at cosmic noon behind the Hubble Frontier Fields cluster MACS1149.6+2223

(Abridged) We combine deep HST grism spectroscopy with a new Bayesian method to derive maps of gas-phase metallicity, nebular dust extinction, and star-formation rate for 10 star-forming galaxies at high redshift ($1.2<z<2.3$). Exploiting lensing magnification by the foreground cluster MACS1149.6+2223, we reach sub-kpc spatial resolution and push the stellar mass limit associated with such high-z spatially resolved measurements below $10^8M_\odot$ for the first time. Our maps exhibit diverse morphologies, indicative of various effects such as efficient radial mixing from tidal torques, rapid accretion of low-metallicity gas, etc., which can affect the gas and metallicity distributions in individual galaxies. Based upon an exhaustive sample of all existing sub-kpc metallicity gradients at high-z, we find that predictions given by analytical chemical evolution models assuming a relatively extended star-formation profile in the early disk formation phase can explain the majority of observed gradients, without involving galactic feedback or radial outflows. We observe a tentative correlation between stellar mass and metallicity gradient, consistent with the downsizing galaxy formation picture that more massive galaxies are more evolved into a later phase of disk growth, where they experience more coherent mass assembly at all radii and thus show shallower metallicity gradients. In addition, we compile a sample of homogeneously cross-calibrated integrated metallicity measurements spanning three orders of magnitude in stellar mass at $z\sim1.8$. We use this sample to study the mass-metallicity relation (MZR) and test the fundamental metallicity relation (FMR). The slope of the observed MZR can rule out the momentum-driven wind model at 3-$\sigma$ confidence level. We find no significant offset with respect to the FMR, taking into account the intrinsic scatter and measurement uncertainties.Comment: 26 pages, 14 figures, and 6 table

The role of lysine palmitoylation/myristoylation in the function of the TEAD transcription factors

The TEAD transcription factors are the most downstream elements of the Hippo pathway. Their transcriptional activity is modulated by different regulator proteins and by the palmitoylation/myristoylation of a specific cysteine residue. In this report, we show that a conserved lysine present in these transcription factors can also be acylated, probably following the intramolecular transfer of the acyl moiety from the cysteine. Using Scalloped (Sd), the Drosophila homolog of human TEAD, as a model, we designed a mutant protein (Glu352Gln Sd ) that is predominantly acylated on the lysine (Lys350 Sd ). This protein binds in vitro to the three Sd regulators-Yki, Vg and Tgi-with a similar affinity as the wild type Sd, but it has a significantly higher thermal stability than Sd acylated on the cysteine. This mutant was also introduced in the endogenous locus of the sd gene in Drosophila using CRISPR/Cas9. Homozygous mutants reach adulthood, do not present obvious morphological defects and the mutant protein has both the same level of expression and localization as wild type Sd. This reveals that this mutant protein is both functional and able to control cell growth in a similar fashion as wild type Sd. Therefore, enhancing the lysine acylation of Sd has no detrimental effect on the Hippo pathway. However, we did observe a slight but significant increase of wing size in flies homozygous for the mutant protein suggesting that a higher acylation of the lysine affects the activity of the Hippo pathway. Altogether, our findings indicate that TEAD/Sd can be acylated either on a cysteine or on a lysine, and suggest that these two different forms may have similar properties in cells

Synergistic effect of expanded graphite-silane functionalized silica as a hybrid additive in improving the thermal conductivity of cementitious grouts with controllable water uptake

Recently, a growing demand for geothermal applications has led to the exploitation of energy efficiently by developing grouting materials in the borehole between pipes and the ground. Therefore, the current study developed newly formulated cementitious grouts by the integration of expanded graphite (EG)-based hybrid additives synthesized by building chemical bridges between silica particles and EG in the presence of amino functional silane coupling agents. These produced hybrid additives with controlled EG and silica ratios were utilized in grout mixtures used in borehole heat exchangers to enhance the thermal conductivity. According to the optimization study on the formulation development of grout mixtures with bentonite, silica sands, cement, and superplasticizer by adding neat EG and EG-based hybrids, the relationship between the carbon amount and water demand was found to have a significant impact on thermal conductivity. The highest thermal conductivity value of 2.656 W/mK was achieved by the incorporation of 5 wt% hybrid additive with the ratio silica/EG of 1:5 compared to the reference grout, which showed a thermal conductivity of 2.373 W/mK. Therefore, the enhancement in thermal conductivity was dependent on the increase in the EG content and also the additive loading ratio, resulting in a slight increase in the water demand

Facile synthesis of graphene from waste tire/silica hybrid additives and optimization study for the fabrication of thermally enhanced cement grouts

This work evaluates the effects of newly designed graphene/silica hybrid additives on the properties of cementitious grout. In the hybrid structure, graphene nanoplatelet (GNP) obtained from waste tire was used to improve the thermal conductivity and reduce the cost and environmental impacts by using recyclable sources. Additionally, functionalized silica nanoparticles were utilized to enhance the dispersion and solubility of carbon material and thus the hydrolyzable groups of silane coupling agent were attached to the silica surface. Then, the hybridization of GNP and functionalized silica was conducted to make proper bridges and develop hybrid structures by tailoring carbon/silica ratios. Afterwards, special grout formulations were studied by incorporating these hybrid additives at different loadings. As the amount of hybrid additive incorporated into grout suspension increased from 3 to 5 wt%, water uptake increased from 660 to 725 g resulting in the reduction of thermal conductivity by 20.6%. On the other hand, as the concentration of GNP in hybrid structure increased, water demand was reduced, and thus the enhancement in thermal conductivity was improved by approximately 29% at the same loading ratios of hybrids in the prepared grout mixes. Therefore, these developed hybrid additives showed noticeable potential as a thermal enhancement material in cement-based grouts

Non-trivial symmetries in quantum landscapes and their resilience to quantum noise

Very little is known about the cost landscape for parametrized Quantum Circuits (PQCs). Nevertheless, PQCs are employed in Quantum Neural Networks and Variational Quantum Algorithms, which may allow for near-term quantum advantage. Such applications require good optimizers to train PQCs. Recent works have focused on quantum-aware optimizers specifically tailored for PQCs. However, ignorance of the cost landscape could hinder progress towards such optimizers. In this work, we analytically prove two results for PQCs: (1) We find an exponentially large symmetry in PQCs, yielding an exponentially large degeneracy of the minima in the cost landscape. Alternatively, this can be cast as an exponential reduction in the volume of relevant hyperparameter space. (2) We study the resilience of the symmetries under noise, and show that while it is conserved under unital noise, non-unital channels can break these symmetries and lift the degeneracy of minima, leading to multiple new local minima. Based on these results, we introduce an optimization method called Symmetry-based Minima Hopping (SYMH), which exploits the underlying symmetries in PQCs. Our numerical simulations show that SYMH improves the overall optimizer performance in the presence of non-unital noise at a level comparable to current hardware. Overall, this work derives large-scale circuit symmetries from local gate transformations, and uses them to construct a noise-aware optimization method

Development of advanced materials guided by numerical simulations to improve performance and cost-efficiency of borehole heat exchangers (BHEs)

[EN] One promising way to improve the efficiency of borehole heat exchangers (BHEs) in shallow geothermal applications is to enhance the thermal properties of the materials involved in its construction. Early attempts, such as using metal tubes in the 1980s or the utilization of thin-foil hoses, did not succeed in being adopted by the market for diverse reasons (cost, corrosion, fragility, etc...). In parallel, the optimization of pipe size, the use of double-U-tubes, thermally enhanced grout, etc. were able to bring the measure for the BHE efficiency, the borehole thermal resistance, from 0.20 to 0.15 K/(Wm) down to 0.08-0.06 K/(Wm) in the best solutions today. A further improvement cannot be expected without development of new, dedicated materials, combining the versatility of plastic like PE with an increased thermal conductivity that matches the respective properties of the rock and soil. This goal was included in the Strategic Research and Innovation Agenda of the European Technology Platform on Renewable Heating and Cooling in 2013. Within an EU supported project, both BHE pipes and grouting materials have been produced prototypically in small amounts, suitable for the first tests in the intended environment. The present work explains the research pathways envisaged and the resulting sensitivity analysis to highlight the influence of some of the most critical parameters that affect the overall performance of a GSHP system. The results have allowed guiding the real development of more efficient new advanced materials for different scenarios representative of different European regions. Finally the developed materials and their properties are discussed, including a comparative assessment about their compliance with reference material properties as currently seen in the BHE market.This article is part of a project that has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 727583.Badenes Badenes, B.; Sanner, B.; Mateo Pla, MÁ.; Cuevas, JM.; Bartoli, F.; Ciardelli, F.; González, RM.... (2020). Development of advanced materials guided by numerical simulations to improve performance and cost-efficiency of borehole heat exchangers (BHEs). Energy. 201:1-17. https://doi.org/10.1016/j.energy.2020.117628117201Alva, G., Lin, Y., & Fang, G. (2018). An overview of thermal energy storage systems. Energy, 144, 341-378. doi:10.1016/j.energy.2017.12.037Li, H., Xu, W., Yu, Z., Wu, J., & Sun, Z. (2017). Application analyze of a ground source heat pump system in a nearly zero energy building in China. Energy, 125, 140-151. doi:10.1016/j.energy.2017.02.108Ozgener, O. (2010). Use of solar assisted geothermal heat pump and small wind turbine systems for heating agricultural and residential buildings. Energy, 35(1), 262-268. doi:10.1016/j.energy.2009.09.018Jensen, J. K., Ommen, T., Markussen, W. B., & Elmegaard, B. (2017). Design of serially connected district heating heat pumps utilising a geothermal heat source. Energy, 137, 865-877. doi:10.1016/j.energy.2017.03.164A. C. Crandall, House heating with earth heat pump, Electr World, 126/19, 94-5 (1946).Moegle, E. (2009). Earth- and buildingsided characteristics of a geothermal energy field with five coaxial tubes erected in 1974 in Schoenaich (County of Boeblingen) – a contribution to history for near-surface geothermic drilling in Europe. Jahresberichte und Mitteilungen des Oberrheinischen Geologischen Vereins, 91, 31-35. doi:10.1127/jmogv/91/2009/31Lundh, M., & Dalenbäck, J.-O. (2008). Swedish solar heated residential area with seasonal storage in rock: Initial evaluation. Renewable Energy, 33(4), 703-711. doi:10.1016/j.renene.2007.03.024Ground coupled heat pumps of high technology - groundhit, Funded by FP6-SUSTDEV - sustainable development, global change and ecosystems: thematic priority 6 under the focusing and integrating community research programme 2002-2006. Project ID: 503063.Go, G.-H., Lee, S.-R., Yoon, S., Park, H., & Park, Sk. (2014). Estimation and experimental validation of borehole thermal resistance. KSCE Journal of Civil Engineering, 18(4), 992-1000. doi:10.1007/s12205-014-0454-xZhang, S., Huang, Z., Li, G., Wu, X., Peng, C., & Zhang, W. (2018). Numerical analysis of transient conjugate heat transfer and thermal stress distribution in geothermal drilling with high-pressure liquid nitrogen jet. Applied Thermal Engineering, 129, 1348-1357. doi:10.1016/j.applthermaleng.2017.10.042Fossa, M., & Minchio, F. (2013). The effect of borefield geometry and ground thermal load profile on hourly thermal response of geothermal heat pump systems. Energy, 51, 323-329. doi:10.1016/j.energy.2012.12.043SPIN-PET, Via R. Piaggio, 32, 56025, Pontedera ,Italy, http://www.spinpet.it//, [Online; accessed 12-December-2019].SILMA, Via Lombardia 97/00/101, Poggio a Caiano, Italy, http://www.spinpet.it//, [Online; accessed 12-December-2019].AIMPLAS, Plastics Technology Centre, Paterna, Spain, https://www.aimplas.net/aimplas/, [Online; accessed 12-December-2019].CAUDAL - Extruline Systems, Puerto Lumbreras (Murcia), Spain, https://www.caudal.es/index.php/en/, [Online; accessed 12-December-2019].ASTM C 666: [Standard Test Method for Resistance of Concrete to Rapid Freezing and Thawing].ASTM C 531-85: Standard test method for linear shrinkage and coefficient of thermal expansion of chemical-resistant mortars, grouts, monolithic surfacings, and polymer concretes.EN 197-1: Cement - Part 1: composition, specifications and conformity criteria for common cements.EN 445: Grout for prestressing tendons - test methods.SS 137244: Concrete testing – hardened concrete – scaling at freezing.RISE Research Institutes of Sweden, Division Samhällsbyggnad – Infrastructure and Concrete Construction, Stockholm, Sweden, https://www.ri.se/sv, [Online; accessed 12-December-2019].UBeG GbR, Wetzlar, Germany, http://www.ubeg.de. [Online; accessed 12-December-2019]

Composite UHPC-AAC/CLC facade elements with modified interior plaster for new buildings and refurbishment. Materials and production technology

The awareness of the environmental impact of the building sector is increasing. Steel reinforced concrete is the most commonly used construction material, though with a high-embodied energy and carbon footprint. Large environmental gains may arise if an alternative to steel reinforced concrete is developed. In this context, ultra-high performance concrete (UHPC) materials are shown to be promising alternatives with advantages such as lower embodied energy and reduced environmental impact. Predictions suggest that UHPC composite elements for building envelopes could have other benefits such as an increased service life, optimised use of building area due to thinner elements and minimised maintenance due to the absence of reinforcement or use of non-corrosive reinforcing materials such as carbon fibres. In the framework of the H-HOUSE project funded by the European Commission, composite elements are developed. The aim is to create facade panels combining an autoclaved aerated concrete or cellular lightweight concrete insulation layer with an external UHPC supporting layer. To enhance occupant comfort and health, hygroscopic materials that are capable to buffer indoor air humidity shall be applied to the inside of such elements. Indoor air humidity levels are expected to be more stable, which shall subsequently improve the indoor climate and minimise potential decay to the construction