International portfolio optimisation with integrated currency overlay costs and constraints

International financial portfolios can be exposed to substantial risk from variations of the exchange rates between the countries in which they hold investments. Nonetheless, foreign exchange can both generate extra return as well as loss to a portfolio, hence rather than just being avoided, there are potential advantages to well-managed international portfolios. This paper introduces an optimisation model that manages currency exposure of a portfolio through a combination of foreign exchange forward contracts, thereby creating a “currency overlay” on top of asset allocation. Crucially, the hedging and transaction costs associated with holding forward contracts are taken into account in the portfolio risk and return calculations. This novel extension of previous overlay models improves the accuracy of the risk and return calculations of portfolios. Consequently, more accurate investment decisions are obtained through optimal asset allocation and hedging positions. Our experimental results show that inclusion of such costs significantly changes the optimal decisions. Furthermore, effects of constraints related to currency hedging are examined. It is shown that tighter constraints weaken the benefit of a currency overlay and that forward positions vary significantly across return targets. A larger currency overlay is advantageous at low and high return targets, whereas small overlay positions are observed at medium return targets. The resulting system can hence enhance intelligent expert decision support for financial managers

The Embodied World Model Based on LLM with Visual Information and Prediction-Oriented Prompts

In recent years, as machine learning, particularly for vision and language understanding, has been improved, research in embedded AI has also evolved. VOYAGER is a well-known LLM-based embodied AI that enables autonomous exploration in the Minecraft world, but it has issues such as underutilization of visual data and insufficient functionality as a world model. In this research, the possibility of utilizing visual data and the function of LLM as a world model were investigated with the aim of improving the performance of embodied AI. The experimental results revealed that LLM can extract necessary information from visual data, and the utilization of the information improves its performance as a world model. It was also suggested that devised prompts could bring out the LLM's function as a world model

CO₂ Emissions from Blade Waste Treatments under Wind Power Scenario in Japan from 2021 to 2100

Nogaki S., Ito L., Nakakubo T., et al. CO₂ Emissions from Blade Waste Treatments under Wind Power Scenario in Japan from 2021 to 2100. Sustainability (Switzerland) 16, 2165 (2024); https://doi.org/10.3390/su16052165.Wind power generation has been introduced to reduce carbon emissions; however, recycling or recovering the waste of wind blades, which contain fibre-reinforced plastic, is difficult. Converting the recovered materials for secondary use is also difficult owing to the decreased strength and low material value. Many countries, including Japan, have not considered the future energy and CO₂ emission scenarios, particularly CO₂ emissions from wind blade waste. Based on these scenarios, Japan has planned to introduce large amounts of onshore/offshore wind power generation through 2050. Therefore, we aimed to evaluate quantitatively the total amount of waste and the global warming potential (GWP) from multiple blade waste treatment processes. Based on the average lifetime of blades (20–25 years), we found that the GWP of wind blade waste treatment in Japan may reach a maximum of 197.3–232.4 MtCO2eq by 2060–2065. Based on this lifetime, the wind blade treatment in 2050 accounted for 63.9–80.1% of the total greenhouse gas emissions in 2050. We also showed that the rise in CO₂ emissions from the wind blade wastes would make up 82.5–93.6% of the potential reduction in the GWP, which is achievable by shifting from thermal to wind power generation

Demand response measures at a small-scale wastewater treatment plant installed with a photovoltaic system

Nakakubo T., Okuno F., Maki S., et al. Demand response measures at a small-scale wastewater treatment plant installed with a photovoltaic system. Journal of Cleaner Production 516, 145730 (2025); https://doi.org/10.1016/j.jclepro.2025.145730.Wastewater treatment plants (WWTPs) consume large amounts of energy, and measures to upgrade WWTPs to become self-sufficient through the use of renewable energy are being promoted. We developed an electricity demand simulation model of a small-scale WWTP with a photovoltaics (PV) system at a 30-min resolution. A demand response (DR) measure for the plant's wastewater treatment process was designed to match a high-load operation with continuous aeration to the PV daily generation curve by utilizing a load-adjustment tank. Similarly, a DR measure for the plant's sludge treatment process was designed to increase the dehydrator operating time and take advantage of seasonal PV generation surpluses by receiving household sludge waste collected from outside of the sewerage area. Self-sufficiency and self-consumption rates were evaluated based on the electricity supply-demand balance at a 30-min resolution under the condition that the total annual PV power generation and total annual demand of the WWTP were approximately equal. Compared to the base scenario that reproduced the electricity demand in the WWTP in FY2018, self-sufficiency and self-consumption rates were both increased by 14.1 % through implementation of the two DR measures under DR-W+S scenario. The improvement of self-sufficiency also led to a reduction of greenhouse gas emissions, and the annual emissions were reduced by 36.3 % under the DR-W+S scenario compared with the base scenario. From the aspect of economic in the 20-year project period, the estimated net present value was turned to be positive in the 14th year under DR-W+S scenario by improving the electricity trade balance

Effectiveness of countermeasure options for chemical facilities against the discharge of chemical substances into rivers caused by a large earthquake: case study of the Yodo river system in Osaka prefecture, Japan

The version of record of this article, first published in Environment Systems and Decisions, is available online at Publisher’s website: https://doi.org/10.1007/s10669-024-09982-x.Technological accidents triggered by natural hazards, which are commonly referred to as Natech events, are rare occurrences yet carry the potential for significant damage. Specifically, the release of hazardous chemicals into the aquatic environment and community water systems poses a grave threat to human health and society. Accordingly, we must conduct assessments that consider the potential consequences of these accidents. In this study, we examined the criteria for implementing spill protection measures to mitigate river spills of chemical substances using information on the amount of chemical substances and their toxicity. The countermeasure options readily available to employees at industrial plants and chemical storage sites where a chemical spill might originate included emergency shut-off valves, bunds and related spill containment structures, and other spill prevention measures. In this case study, a combination of countermeasure options was evaluated to examine the effectiveness of spill mitigation in the Yodo River located in the Kyoto Prefecture of Japan. Results of the case study showed that bunds were emerged as the most useful countermeasure option, reducing the probability of accidents occurring and impact of accidents. We also defined a methodology for calculating the chemical storage volumes appropriate for different countermeasures to ensure that the concentration of chemicals that could reach the water intake does not exceed the standard values. We believe that these methodologies can help chemical-handling companies make decisions when countermeasure options for responding to a chemical spill into a river. Chemical-handling companies can estimate the risk to downstream water treatment plants in the chemical spill, which can also help them consider mitigation measures

無極性溶媒中での帯電微小液滴の形成および電界を用いた自己組織的アセンブリ

学位の種別: 課程博士審査委員会委員 : （主査）東京大学教授 下山 勲, 東京大学教授 藤田 博之, 東京大学教授 中村 仁彦, 東京大学教授 鈴木 雄二, 東京大学教授 竹内 昌治University of Tokyo(東京大学