254 research outputs found
Inversion Phenomena of the Anisotropies of the Hamiltonian and the Wave-Function in the Distorted Diamond Type Spin Chain
We investigate the ground-sate phase diagram of the XXZ version of the S=1/2
distorted diamond chain by use of the degenerate perturbation theory near the
truncation point. In case of the XY-like interaction anisotropy, the phase
diagram consists of the Neel phase and the spin-fluid phase. For the Ising-like
interaction anisotropy case, it consists of three phases: the ferrimagnetic
phase, the Neel phase and the spin-fluid phase. The magnetization in the
ferrimagnetic phase is 1/3 of the saturation magnetization. The remarkable
nature of the phase diagram is the existence of the Neel phase, although the
interaction anisotropy is XY-like. And also, the spin-fluid phase appears in
spite of the Ising-like interaction anisotropy. We call these regions
"inversion regions".Comment: 7 pages, 4 figure
A Numerical Method Combining the IADI Method with the Modified Picard Iteration Method for Solving Multi-Dimensional Saturated-Unsaturated Flow Equation
Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv
Uncertainty assessment of water resources and long-term hydropower generation using a large ensemble of future climate projections for the Nam Ngum River in the Mekong Basin
[Study region] The Nam Ngum River Basin, the major tributary of the Mekong River, is located in the Laos PDR. [Study focus] This study aims to assess the sensitivity of Nam Ngum 1 reservoir operation to water resource uncertainty driven by a combination of climate change and upstream cascade dam development. [New hydrological insights for the region] Precipitation projections of the basin under a 4° increase scenario vary in the range of −9.6 % to +6.9 %, compared to the historical observed precipitation (present climate). The impact of climate change on hydropower resources was investigated. Based on the combined effect of climate change and upstream cascade dam development, the projected inflow of the Nam Ngum 1 reservoir at the full development stage will change from −16.0 % to +6.5 %, which results in a large range of annual energy production changes from −18.8 % to +2.8 % compared to the current condition (present climate and existing dam stage). Furthermore, water losses from the reservoir due to water discharge from the spillway for extreme floods and evaporation are expected to increase with increasing temperature, which will lead to a loss in energy production. Our study indicates that the operation of hydropower should be adapted to the effects of climate change. This information can be used by stakeholders to propose water resource management strategies
Novel framework for assessing long‐term flood risk management pathways focusing on river channel improvement and amenity policies
Many urban areas at higher flood risk owing to climate change, and mitigating these risks requires a combination of structural and nonstructural adaptation measures. Previous studies assessing adaptation measures are limited in quantifying the effects of climatic and social changes. As an interdisciplinary approach, this study developed an agent-based model of household locational choices and combined an advanced method for deriving on-site analytical flood risk curves (90 m resolution) to explicitly reflect the present/future flood risk on the flood insurance rate. To evaluate river channel improvements and amenity policies, the proposed framework was applied to a middle stream area of the Yodo River basin, Japan. The simulation results indicated that (1) both the design level and river pathway improvements influence the flood risk (2) developing wider areas over low- and no-risk areas rather than the intensive induction to limited no-risk areas lead to a more effective reduction in flood risk. In addition, (3) an appropriate amenity policy may contribute to the attenuation of the inequality of flood risk among regions owing to the pathway of improvement. The proposed interdisciplinary approach will help decision makers in long-term flood risk management
Real-time optimization of a large-scale reservoir operation in Thailand using adaptive inflow prediction with medium-range ensemble precipitation forecasts
Study region: The Sirikit Dam in the Nan River Basin is located on a main tributary of the Chao Phraya River in Thailand. Study focus: This study investigates forecasting river flows and real-time optimization of dam release using a distributed hydrological model with ensemble weather forecasting for reservoir operations which provide hydropower and irrigation facilities in Thailand during a case study of the 2019 drought event. Medium-range ensemble precipitation forecasts were employed using a hydrological model to predict the real-time reservoir inflow. Real-time optimization of the water release strategy determined a week in advance with an effective initial condition for hydropower generation and irrigation was conducted with different scenarios using dynamic programming considering inflow predictions. New hydrological insights for the region: The medium-range ensemble precipitation forecast conducted by the European Centre for Medium Range Weather Forecasts was used to quantify precipitation for the study basin. The ensemble precipitation forecast with the hydrological model was employed for inflow prediction of the study basin which was located in a tropical climate with a distinct wet and dry season. The initial conditions of the hydrological model largely influenced the real-time inflow forecast. To determine the initial conditions of the model, the empirical data assimilation considering a drainage area factor was utilized and observed precipitation data were used for model input forcing data during the initial analysis period. This method improved the reservoir inflow prediction and real-time reservoir optimization using dynamic programming with considering ensemble forecasts provided more efficient operating decisions than employing historical data. The resulting information will be useful for water resource management, which may be adapted to other basins in the study region
Organellar Glue: A Molecular Tool to Artificially Control Chloroplast–Chloroplast Interactions
細胞小器官を接着する新技術「オルガネラグルー」を開発 --オルガネラ間コミュニケーションの操作に期待--. 京都大学プレスリリース. 2022-09-30.Organelles can physically interact to facilitate various cellular processes such as metabolite exchange. Artificially regulating these interactions represents a promising approach for synthetic biology. Here, we artificially controlled chloroplast–chloroplast interactions in living plant cells with our organelle glue (ORGL) technique, which is based on reconstitution of a split fluorescent protein. We simultaneously targeted N-terminal and C-terminal fragments of a fluorescent protein to the chloroplast outer envelope membrane or cytosol, respectively, which induced chloroplast–chloroplast interactions. The cytosolic C-terminal fragment likely functions as a bridge between two N-terminal fragments, thereby bringing the chloroplasts in close proximity to interact. We modulated the frequency of chloroplast–chloroplast interactions by altering the ratio of N- and C-terminal fragments. We conclude that the ORGL technique can successfully control chloroplast–chloroplast interactions in plants, providing a proof of concept for the artificial regulation of organelle interactions in living cells
Deep variational quantum eigensolver for excited states and its application to quantum chemistry calculation of periodic materials
A programmable quantum device that has a large number of qubits without fault-tolerance has emerged recently. Variational quantum eigensolver (VQE) is one of the most promising ways to utilize the computational power of such devices to solve problems in condensed matter physics and quantum chemistry. As the size of the current quantum devices is still not large for rivaling classical computers at solving practical problems, Fujii et al. proposed a method called “Deep VQE”, which can provide the ground state of a given quantum system with the smaller number of qubits by combining the VQE and the technique of coarse graining [K. Fujii, K. Mitarai, W. Mizukami, and Y. O. Nakagawa, arXiv:2007.10917]. In this paper, we extend the original proposal of Deep VQE to obtain the excited states and apply it to quantum chemistry calculation of a periodic material, which is one of the most impactful applications of the VQE. We first propose a modified scheme to construct quantum states for coarse graining in Deep VQE to obtain the excited states. We also present a method to avoid a problem of meaningless eigenvalues in the original Deep VQE without restricting variational quantum states. Finally, we classically simulate our modified Deep VQE for quantum chemistry calculation of a periodic hydrogen chain as a typical periodic material. Our method reproduces the ground-state energy and the first-excited-state energy with the errors up to O(1)% despite the decrease in the number of qubits required for the calculation by two or four compared with the naive VQE. Our result will serve as a beacon for tackling quantum chemistry problems with classically-intractable sizes by smaller quantum devices in the near future
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