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令和2年度 京都大学化学研究所 スーパーコンピュータシステム 利用報告書

令和3年度 京都大学化学研究所 スーパーコンピュータシステム 利用報告書

Metaheuristics are approximation methods used to solve combinatorial optimization problems. Their performance usually depends on a set of parameters that need to be adjusted. The selectionof appropriate parameter values causes a loss of efficiency, as it requires time, and advanced analytical and problem-specific skills. This paper provides an overview of the principal approaches to tackle the Parameter Setting Problem, focusing on the statistical procedures employed so far by the scientific community. In addition, a novel methodology is proposed, which is tested using an already existing algorithm for solving the Multi-Depot Vehicle Routing Problem.

9 pages, 7 figures.-- Presented at Conference: "Physics and Simulation of Optoelectronic Devices X" (San Jose, CA, USA, Jan 21, 2002)., Semiconductor lasers with optical feedback are prone to exhibit unstable behavior. When working near threshold with moderate to low optical feedback, intensity dropouts are observed. These intensity drops, also called low-frequency fluctuations, occur both in single-mode and multimode semiconductor lasers. In this paper, the dynamics of the power distribution between the longitudinal modes of a multimode semiconductor laser is experimentally and numerically analyzed in the low-frequency fluctuation regime. It is observed that power dropouts of the total intensity, corresponding to drops in the dominant modes of the laser, are invariably accompanied by sudden activations of several longitudinal side modes. These activations are seen not to be simultaneous to the dropouts of the main modes, but to occur after them. The phenomenon is statistically analyzed in a systematic way, and the corresponding delay is estimated, leading to the conclusion that the side mode activation is a consequence of the dropouts of the dominant modes. A multimode extension of the Lang-Kobayashi equations is used to model the experimental setup. Numerical simulations also exhibit a time delay between the side-mode activation and the power dropout of the total intensity., We acknowledge financial support from Ministerio de Ciencia y Tecnologia (Spain), under projects PB98-0935, BFM2000-0624 and BFM2001-2159, from the EU IST network OCCULT, and from the Generalitat de Catalunya, under project 1999SGR-00147. FR is supported by the Inter-University Attraction Pole program (IAP IV/07) of the Belgian government.

Understanding how climate change accelerates or slows down the process of material deterioration is the first step towards assessing adaptive approaches for the preservation of historical heritage. Analysis of the climate change effects on the degradation risk assessment parameters like freeze-thaw cycles and salt crystallization is also a key parameter when considering mitigating actions. Due to the vulnerability of cultural heritage in Iran to climate change, the impact of this phenomenon on basic parameters like temperature was analyzed. Choosing an appropriate regional climate model is the first and most crucial step in the analysis of climate change effects on heritage. The outputs of two different regional climate models: the ALARO-0- SURFEX model (Ghent University, Belgium) and the REMO model (HZG-GERICS, Germany) were analyzed to find out which model is more adapted to the region. So the focus of this research is mainly on the evaluation process to find a feasible approach for validation study to determine the reliability of each model. For model validation, a comparison between model data and observations was performed for 30 years from 1980-2017. Besides, some climatic parameters which are likely critical for heritage like freeze-thaw cycles were studied to find out how reliable these models are in the field of building pathology.

Current Topics and Trends on Durability of Building Materials and Components. Proceedings of the XV edition of the International Conference on Durability of Building Materials and Components (DBMC 2020) Barcelona, Spain 20 – 23 October 2020, ISBN:978-84-121101-8-0

Bio-based materials are gaining importance in the building industry, as the focus on sustainability and life-cycle-assessment has increased substantially over the last decade. Wood and wood-engineered products as well as insulation materials made from cellulose, wood, flax, hemp, etc. are increasingly used. These materials are made from renewable resources and with considerably lower energy consumption than various other building materials, such as insulation polymers, steel and concrete. As steel can corrode and concrete can rot, so can bio-based building materials degrade over time when exposed to those conditions that favour decay. Since fungi cause not only aesthetical degradation, but can also severely compromise the structural integrity of a building component this is critical for any service life approach. Consequently, a proper understanding of the fungal susceptibility of bio-based materials is needed, both for optimal application of bio-based materials as for the design of new materials. Based on a combination of tests we try to unravel the role of the material’s chemical components, structure and moisture dynamics on its fungal susceptibility, as well as the interaction between those material characteristics. In a first test set-up, the ‘paste test’, the material’s structure is removed and fungal growth is assessed over time in 2D, with only the material’s chemical components playing a role. In the second test set-up, the ‘X-ray CT test’, fungal development is assessed non-destructively in 3D with X-ray CT, giving an indication of moisture production and distribution over time, in relation to the material’s structure. By comparing the results, we have a better idea of how much each material characteristic influences fungal susceptibility. This knowledge can then be used for optimising fungal testing of bio-based materials, ensuring optimal application and providing the building industry with the confidence they need to pave the way to a more sustainable future.

During a rain event, most of the raindrops reaching the facade either splash back or run off the exterior surface of the facade. However, it is evident that also a portion of the water infiltrates through the open joints of a ventilated facade. The infiltrated water may either be drained in the cavity to the bottom of the wall or reach the insulation layer. If there are any deficiencies present in the insulation layer or at the connection of the brackets, the infiltrated water might introduce problems. Additionally, if the cavity is not able to drain all the infiltrated water or adhered droplets to one of the cavity surfaces do not dry out, moisture problems might occur. Experiments were conducted to determine the infiltration rate through ventilated facades with open joint widths of 5 mm, 10 mm and 15 mm and cavity widths ranging from 190 mm to 40 mm. It was observed that the amount of infiltrating water was larger for larger joints widths. Due to the larger kinetic energy of the drops flowing through the larger joint widths, the drops were able to reach the exterior surface of the insulation layer, even for large cavity widths. The results from the experimental assessment were used as input parameters for hygrothermal simulations to determine the risk of moisture problems.

Capillary imbibition is a transport phenomenon occurring in concrete structures exposed to weathering, frequently in direct connection with the resistance against different deterioration processes. This property depends on the volume and connectivity of pores. For ground granulated blast-furnace slag (GGBFS) and fly ash blended concrete mixes, the pore refining action of these supplementary cementitious materials plays a positive role in the disconnection of the capillary porosity and consequent reduction of the capillary imbibition rate. Moreover, for this particular transport process, primary and secondary transport rates can be defined in connection with different driving mechanisms. This allows a complementary description of the pore structure of concrete. In this paper, blended concrete mixes were prepared by substituting 20, 40 and 60 % of OPC by GGBFS, and 20, 30 and 40 % of OPC by fly ash. The pore structure of these concretes is assessed by water absorption under vacuum and mercury intrusion porosimetry after curing periods of 28 and 90 days. Long-term capillary imbibition tests were also performed and primary and secondary imbibition rates are computed by a novel approach that considers their linear evolution with the fourth root of time. Results show the refinement action of GGBFS and fly ash by a softening in the transition stage between the primary and secondary imbibition periods. A low water flow rate is consequently correlated with the increased tortuosity of samples.

Construction project costs often reach values higher than planned. Accuracy in project cost estimation is one of the most important criteria for project success, even for its sustainability.The main idea of this research is to examine the relationship between realized cost and contracted cost values for residential buildings. The aim of the research is to determine the mathematical relationship between realized and planned costs in the project implementation phase by using a few mathematical methods and some machine learning methods in comparison to linear regression. This would enable validation of methods themselves by comparing and evaluating the obtained relevant parameters.Comparison would be performed on two levels, based on its general characteristics, as well as on the results of their application on the basis of 24 building reconstructions and new buildings by comparing the mean absolute percentage error (MAPE) and the determination coefficient (R2) using Predictive Modelling Software DTREG (pronounced D-T-Reg). The relationship of realized and planned costs will be determined for the building as a whole and for certain types of construction works. That relationship would enable more realistic budget planning of similar future projects. Cost overrun factors will be analysed for particular types of construction works, as well as the probability of their occurrence, and what measures should be undertaken to prevent or reduce them in similar future projects. The phenomenon known in project planning as "optimism bias" will be analysed in the context of research focus of exceeding the construction cost.