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1. No Poverty
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2. Zero Hunger
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3. Good Health and Well-being
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4. Quality Education
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5. Gender Equality
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6. Clean Water and Sanitation
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7. Affordable and Clean Energy
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8. Decent Work and Economic Growth
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9. Industry, Innovation and Infrastructure
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10. Reduced Inequality
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11. Sustainable Cities and Communities
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12. Responsible Consumption and Production
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13. Climate Action
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14. Life Below Water
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15. Life on Land
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16. Peace and Justice Strong Institutions
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17. Partnerships to achieve the Goal
13. Climate Action: 24
- 1. No Poverty
- 2. Zero Hunger
- 3. Good Health and Well-being
- 4. Quality Education
- 5. Gender Equality
- 6. Clean Water and Sanitation
- 7. Affordable and Clean Energy
- 8. Decent Work and Economic Growth
- 9. Industry, Innovation and Infrastructure
- 10. Reduced Inequality
- 11. Sustainable Cities and Communities
- 12. Responsible Consumption and Production
- 13. Climate Action
- 14. Life Below Water
- 15. Life on Land
- 16. Peace and Justice Strong Institutions
- 17. Partnerships to achieve the Goal
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View Detail-
Ecosystem Restoration of Disturbed Areas
Promoting eco-friendly restoration of ecosystems that have been disturbed by natural or human activities through facilitation.
Facilitation refers to a phenomenon whereby the establishment of a certain plant prompts the invasion and establishment of another species. In ecosystems that have suffered catastrophic damage due to a major disturbance such as a volcanic eruption, fire, tsunami or mining, the detection and introduction of such facilitators will help rapid and eco-friendly ecosystem restoration.
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Fig. Platanthera metabifolia, which has taken root in a patch of Mineyanagi willow on Mt. Komagatake in Oshima after its major eruption in 1920.
The Mineyanagi willow promotes the colonization by many species and thereby enhances ecological diversity . -
Fig. Relationship between coverage of M. sinensis, a facilitator, and the number/density of woody plants on a ski slope in Sapporo (plot size: 4 m2).
The colonization of M. sinensis prompts an increase in the number of woody plants, so the creation of M. sinensis grasslands will lead to the growth of natural forests without afforestation efforts.
Research
Ecosystem restoration after large-scale disturbance is often an urgent task, but it has often been difficult to establish a target plant species in a disturbed environment. A facilitator is a plant species that prompts the establishment of other species once it has been established. If we can detect and establish a facilitator in the respective disturbed areas to prompt the invasion and establishment of the target species there, it will be possible to quickly restore ecosystems in a cost-effective manner with minimal human effort. Therefore, this is an ecofriendly technology for ecosystem restoration.
So far, we have found that the white beak-sedge (Rhynchospora) is functioning as a facilitator in the post-mined peatland of Sarobetsu Mire, and the Mineyanagi willow in Mt. Komagatake in Oshima, Hokkaido. Microtopography modification has also been found effective as a means of introducing facilitators.Shiro Tsuyuzaki Professor -
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Elucidation and Application of Ecosystem Recovery Mechanisms after Large-scale Fires
Toward the mitigation of global warming
In the Arctic region of North America, the scale of wildfires is increasing due to global warming. As a result, the way ecosystems recovery progresses after fires is changing, and it is urgent to elucidate the mechanism of ecosystem recovery from a new perspective. It is also necessary to develop various methods for ecosystem restoration after large-scale disturbance by applying the knowledge obtained in this study.
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The landscape of a black spruce forest after a large fire in Alaska in 2004 (photo taken in 2005). With conventional fires, total destruction is rare, but with this fire, even the organic layer was burned away. As a result, the way how ecosystem recovery progresses has changed. It is necessary to elucidate the transition mechanism and develop conservation and restoration methods as soon as possible.
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Changes in key ecosystem functions caused by wildfires. In the short term, CO2 is directly released during fires, and in the long term, CO2 absorption is reduced due to reduced photosynthesis and methane is released due to thawing of the permafrost. Thus, there are positive (exacerbating) feedback effects on global warming.
Research
The belts of taiga and tundra in Alaska is a fire-prone area associated with lightning strikes, and ecosystem recovery has thus been acclimatized to fire. In the past, the fires were mostly canopy fires with low fire intensity that did not lead to the complete burning of organic layers including peat. In particular, black spruce was dominant on north-facing slopes, and fast forest regeneration was achieved immediately after canopy fires due to dispersion of black spruce seeds.
However, with the development of climate changes, wildfires are increasing in both intensity and frequency. During the 2004 Alaska wildfires, the total area burned exceeded that of Shikoku (Japanese fourth mainland), and the organic layer was also burned away. As a result, ecosystem recovery after large wildfires greatly differs from that after forest canopy fires. In particular, the existence of an organic layer is essential for seed germination and growth, and the development of methods to promote the establishment of Sphagnum moss as a base material is essential for organic matter accumulation. In addition, we studied the impact of wildfires on the ecosystems in the tundra zone.Shiro Tsuyuzaki Professor -
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A New Plant Growth Promotion Technology That Stimulates Growth
Next generation biomass production using wastewater and the possibility of using symbiotic bacteria for plant factories
A completely new growth-promoting bacterium, P23, was discovered in ukikusa (subfamily Lemnoideae) at the Hokkaido University Botanical Garden. The P23 bacterium accelerates the growth of plants by stimulating a surface switch. Ukikusa is a high value-added biomass that grows on wastewater as a fertilizer, and symbiosis with P23 doubles its production rate.
Research
The aquatic plant known as ukikusa is a soft biomass that can grow by absorbing nitrogen and phosphorus from wastewater and contains almost no lignin or cellulose. Its protein content is approximately 30%, comparable to that of soybeans, and its starch accumulation can reach 50%, depending on the growth environment. Its protein can be used directly as livestock feed, while its starch is useful as a raw material for biofuel production and the production of HMF, a precursor for chemical products. To improve the production yield of the next generation biomass, we are developing technology to promote plant growth with the symbiotic action of surface bacteria. In addition to ukikusa cultivation, it is expected to apply this technology to hydroponic cultivation of vegetables and cereals (plant factories). This is an old but new biotechnology that does not involve genetic modification and follows the natural order of things.
Masaaki Morikawa ProfessorDoctor of Engineering -
Analysis of Thermo-acoustic Vibration Generated by Combustion Equipment
Thermo-acoustic vibrations often occur in combustion devices and combustion gas exhaust systems, causing noise and reducing the life of the combustion devices. This is caused by acoustic pressure fluctuations coupled with heat generation fluctuations in combustion and exhaust systems. With this study, we analyze this physical process and investigate the suppression technology.
Research
Thermo-acoustic vibrations are often generated in combustion equipment and combustion gas exhaust systems, leading to noise generation and reduction of the life of combustion equipment. This is caused by acoustic pressure fluctuations linked to heat generation fluctuations in the combustion and exhaust systems, and we are analyzing the physical processes that cause these fluctuations and investigating techniques to suppress them. With this study, a single circular tube is filled with a combustible premixed gas that is ignited at one end, and a thermo-acoustic vibration phenomenon that occurs during flame propagation in the tube is used. Various boundary conditions (open end condition, direction of propagation, composition of the gas mixture, diameter and length of the propagating tube, structure of the flame surface, etc.) are applied to this propagation phenomenon to induce the thermo-acoustic vibration phenomenon, and the factors behind it can then be understood using the combustion instability analysis method. The vibration phenomena reproduced here are observed in a simplified system, but they are general phenomena and lead directly to the understanding of thermo-acoustic vibration phenomena that occur in actual combustion equipment and exhaust systems.
Osamu Fujita Professor -
Boundary Element Analysis Framework and Distributed H-matrix Method
Realizing cutting-edge, large-scale, high-precision analysis
We have developed a software framework for high-performance boundary element analysis in a parallel computing environment. We have also developed a distributed parallel H-matrix library, which is effective to accelerate a BEM analysis, and evaluated its performance on programs in various applications.
Research
In this study, we developed a parallel boundary element analysis framework as part of the JST CREST project on “Application Development and Execution Environment with Automatic Tuning Mechanism.” By using this framework, it is possible to develop boundary element analysis programs for large-scale parallel computing systems with a small programming cost. We also developed a library of H-matrices, which approximates dense matrices with less data using low-rank approximation. This library can be used for analysis of N-body problems in addition to boundary element analysis, and is already being used for earthquake simulation on supercomputers. There is no other H-matrix library that supports hybrid parallel processing utilizing multiple threads and processes, and this is a unique feature of this research.
Takeshi Iwashita Professor -
Creation of Highly Active Catalysts Using Polystyrene-bridged Bisphosphine Ligands
Design of metal complex catalysts using polymeric carriers as the reaction site and development of an efficient synthetic processes
We have developed polystyrene-crosslinked bisphosphine ligands that can be used to create polymer-supported metal catalysts. Thanks to the effect of polymer topology, it is possible to suppress disproportionation of metal complexes and deactivation of catalysts caused by metal aggregation. It is particularly useful as a ligand for first transition series metal catalysts.
Research
Heterogeneous (insoluble) metal catalysts, which are easy to separate from the reaction mixture and have excellent reusability, can be used for organic synthesis in an environmentally-friendly manner. However, compared with the corresponding homogeneous (soluble) catalysts, they have a problem of reduced catalytic activity. We have developed a polystyrene-crosslinked bisphosphine ligand, PS-DPPBz, based on the topological control of polymer chains. Since this ligand is effective in generating highly active monochelate mononuclear transition metal complexes, it has significantly improved the efficiency of Ni-catalyzed reactions such as amination coupling of aryl chlorides and ester-azole coupling. PS-DPPBz can also be used for substrates to which it is difficult to apply existing catalysts. PS-DPPBz can be separated by filtration and reused, so it is expected to use this catalyst for industrial purposes.
Masaya Sawamura Professor -
Detoxification and Removal of Nitrogen from Carbon Resources Using Nanoparticles
Use of nanoparticles for fuel nitrogen pre-removal and high-temperature gas purification
To establish principles for advanced utilization of carbon resources in harmony with the global environment is one of the most important research themes for the next generation. With this study, we aim to develop a catalytic process that can efficiently convert carbon resources into clean energy using nanoscale metal and metal oxide particles.
Research
Nitrogen in carbon resources (Fuel-N) is emitted as NOx and N2O during combustion. During high-temperature gasification, it is mainly converted to NH3, which becomes a source of NOx in later-stage gas combustion. With this study, we have worked on the development of a method to convert Fuel-N into harmless N2 through a pyrolysis process prior to combustion or gasification, and found that Ca ions supported by the ion-exchange method change into CaO nanoparticles during pyrolysis and catalyze the formation of N2 formation.
We have also found that Fe ions, which are originally contained in lignite coal, and FeOOH, which is abundantly found in brown iron ore, readily become metallic iron nanoparticles during the heating process, and that N2 is selectively produced during the decomposition reaction of NH3, pyridine and pyrrole by this catalyst. Since these N-containing species are contained in the crude gas produced during coal gasification, we are working to develop a new high-temperature gas purification method for the removal of these compounds.Naoto Tsubouchi Associate Professor -
Development of a Non-destructive CT-XRD Coupling Method and Its Application
Visualization of the microstructure of hardened cement
To develop innovative cement-hardening materials, we are devising a non-destructive integrated CT-XRD method, a novel measurement method combining the CT method to obtain geometric and spatial information on microstructures inside concrete with an accuracy of several microns, and a diffraction method to investigate hydrates and alterations in the region of interest.
Research
Concrete is structurally hardened by binding rock (aggregate) through a hydration reaction between cement and water. As a structural material, concrete is intended to withstand loading and certain weather/environmental conditions, but these may cause cracking of the concrete, which may progressively deteriorate due to strong acids and other chemical reactions caused by erosion and materials from the atmosphere, seawater and groundwater that come in contact with it. To stably use the social infrastructure for a long period of time, it is important to be able to see inside the internal structure of concrete with “bug eyes” and find any abnormalities that have occurred.
With the pioneering “non-destructive integrated CT-XRD method,” the sample is irradiated with high-intensity X-rays from synchrotron radiation to selectively visualize 3D structures from transmitted monochromatic X-rays at 25 keV. Energy-dispersive X-ray diffraction is also performed in specific regions of interest through multiple slit operations to identify hydrates (portlandite, calcite, etc.), their alteration and aggregate minerals.Takafumi Sugiyama Professor -
Development of Polymer Electrolyte Fuel Cells with Excellent Sub-zero Start-up Performance
Elucidation of micro-nano freezing phenomena in fuel cells
We are visualizing the freezing phenomenon near the reaction layer in fuel cells, which cannot normally be observed, using an ultracold electron microscope. By combining electrochemical measurements, we are also elucidating the freezing phenomenon of produced water, which becomes a problem in cold climate applications, and are developing fuel cells with excellent sub-zero activation performance.
Research
In the polymer electrolyte fuel cell (PEFC), which is a highly efficient and clean energy conversion device, the water produced by the reaction passes through a catalyst layer pores of several tens of nanometers in diameter and is discharged into the gas diffusion layer and gas supply channel through the microporous layer (MPL), which is a porous layer with pores of several micrometers in diameter, as shown in the left figure below. In the activation in a sub-zero environment in cold regions, the produced water freezes, causing the power generation to stop and degrade. However, the phenomenon is on a micro-nano scale and is thus difficult to measure, so the phenomenon is still insufficiently understood. This study is aimed to clarify where the water freezes and what mechanism leads to performance shutdown and aging degradation. We will conduct microscopic observation, electrochemical measurement and catalyst layer model analysis to contribute to the improvement of activation resistance and extension of the service life. The middle figure below shows the catalyst layer filled with ice, and the right figure is a structural schematic of the catalyst layer modeled in the analysis.
Yutaka Tabe Professor -
Elucidation of Combustion Phenomena Using Microgravity Fields
Combustion phenomena are accompanied by a local temperature rise, which always results in natural convection in the surrounding air . This complicates the phenomenon and makes it difficult to fundamentally understand it. In this study, we will try to understand the combustion phenomena from a fundamental standpoint by utilizing the microgravity environment to remove the natural convection.
Research
Combustion phenomena are accompanied by a local temperature rise, which always results in natural convection in the surrounding air . This complicates the phenomena and makes it difficult to understand the fundamentals. In this study, we will utilize the microgravity environment to remove the natural convection and understand the fundamental processes (diffusion, heat conduction, soot formation, ignition, flame propagation, etc.) of combustion phenomena, which will be useful for numerical prediction and modeling of combustion devices. Hokkaido University has an approximately 40-meter drop tower that can be used at any time, making it easy to conduct microgravity experiments, and is also involved in international joint research to conduct microgravity experiments using aircraft and the International Space Station. Thus, we are in a favorable environment to conduct combustion research using the microgravity environment.
Osamu Fujita Professor -
Exploring Strategies for Coexistence between Indigenous Siberians and Wildlife
A practical study on an adaptive wildlife management system for utilization and protection of wild animals and birds
To reduce conflicts between local communities and wildlife (e.g., agricultural damage and invasive species problems), we plan and implement surveys and countermeasures with the participation and initiative of local residents, and provide bottom-up policy support. In recent years, we have also been involved in the establishment of wildlife sanctuaries to protect the livelihoods of indigenous people in Siberia.
Research
◇ Survey of reindeer and other wild animals and establishment of protected areas
In the Arctic region of the Republic of Sakha in the Russian Federation, which is the closest Arctic area to Japan, we have attached satellite transmitters to wild animals (e.g., reindeer, musk ox, wolf) used by indigenous people to clarify the effects of global warming and seasonal migration. Based on this information, we are working with indigenous groups, local governments, hunting groups and other parties to establish and evaluate protected areas and hunting areas that contribute to traditional livelihoods.
◇ Survey of Migratory Birds in Japan and Evaluation of International Protected Areas
Siberia is an important breeding ground for migratory birds that use the arctic and other northern regions, including Japan, but their habitats are changing due to global warming. Therefore, we are conducting surveys, research, and practical applications to comprehensively evaluate the impact of global warming on habitat protection areas by creating a network of different surveys that have been conducted in individual countries.Shirow Tatsuzawa Assistant Professor -
Fire-safety Improvement Technology for Lithium-ion Batteries
The use of lithium-ion batteries has been expanding rapidly due to their high energy density. On the other hand, since organic solvents are used in lithium-ion batteries, it is important to ensure their fire safety. With this study, we focus on the combustion phenomenon of organic solvents and study combustion inhibition technology.
Research
The use of lithium-ion batteries has been expanding rapidly due to their high energy density. On the other hand, since organic solvents are used in the battery electrolyte, it is important to ensure their fire safety. With this study, we intend to develop a method to quantify the effect of adding a combustion inhibitor to suppress the combustion of organic solvents, search for additives that are effective in suppressing combustion, and study the effect of the lithium salt contained in the electrolyte itself on the flammability of organic solvents. We also conduct modeling and numerical analysis of fire phenomena taking the elementary reaction kinetics of combustion in an electrolyte into consideration.
Osamu Fujita Professor -
Glacier Ice Sheet-Ocean Interactions in Greenland
Warming Greenland's Coastal Environment
In Greenland, which is located in the Arctic region, the mass of the glacier ice sheet has been rapidly decreasing in recent years. We are conducting research using field surveys and satellite data, with the focus on the environmental changes along the coast of Greenland, where the glacier ice sheets meet the ocean.
Research
Greenland is approximately six times the size of Japan, and 80% of its area is covered by glacial ice sheets. The ice in Greenland is rapidly diminishing due to the effects of global warming. In particular, glaciers flowing from the ice sheets into the ocean are undergoing remarkable changes, suggesting the influence of the warming ocean. In addition, the inflow of meltwater into the ocean is expected to raise sea levels and cause changes in ocean circulation and ecosystems, although the details are still unclear. Against this background, we are working to understand the interaction between glacier ice sheets and the ocean, and the resulting changes in the coastal environment of Greenland. We are conducting field observations and satellite data analysis with special focus on the Kanak region in the northwestern part of the country. Ultimately, we aim to clarify the impact of environmental changes on fisheries and traffic, and to provide feedback to local residents.
Shin Sugiyama Professor -
Glowing Plankton
GFP and luciferase in copepods
Marine organisms include various bioluminescent creatures. We have identified a green fluorescent protein (GFP) and a secreted luciferase (luminescent enzyme) from copepods, the most dominant plankton species.
Research
Zooplankton serves as energy transmitters in marine ecosystems, passing basic production to higher organisms. The dominant zooplankton species in the Arctic Ocean are copepods, most of which have a lifespan of one year or less, but their samples can be preserved semi-permanently with formalin fixation, making them an ideal taxonomic group for assessing the interannual variability in biological production in the region. Some species of copepods are also bioluminescent. It is thought that they emit light when they are about to be predated upon in dark waters, and use it to distract predators. We have identified a fluorescent protein (GFP) and a luciferase (luminescent enzyme) from copepods.
Atsushi Yamaguchi Associate Professor -
High-efficiency Semiconductor Solar Cells
New-type solar cell consisting of a multi-striped semiconductor with orthogonal photon-photocarriers that was coupled to a waveguide.
Temperature rise and device degradation are suppressed by simultaneous optimization of light absorption and photocarrier collection, as well as photoelectric conversion over the entire solar spectrum by multiple semiconductor stripes. This leads to the realization of a highly efficient 2-dimensional PhotoReceptoConversion Scheme (2DPRCS).
Research
In conventional solar cells, there is a trade-off between carrier collection and the number of absorbed photons because the photo carrier migration direction and the light travel direction are parallel. Based on the orthogonality between the carrier migration direction and the light travel direction, it was possible to optimize both the light absorption and the carrier collection efficiency. Since the sunlight is sequentially photoelectrically converted from high- to low-energy components over the entire spectrum, thermal dissipation is minimized and high efficiency can be achieved. A waveguide type light collection system with a light wave direction conversion membrane can realize a photovoltaic system that is resistant to diffuse light. By preventing high-energy photons from entering the mid-gap and narrow-gap semiconductors, bond degeneration can be prevented and the life of the device can be extended. It is possible to realize the ultimate concentrator solar cell system, which is strong even in cloudy weather, has high conversion efficiency close to the thermodynamic limit, and is highly reliable.
Akira Ishibashi Professor -
Infrared Metamaterials Produced by Microfabrication of High Temperature Resistant Materials
Development of materials and devices that manipulate mid- to far-infrared radiation
It is expected that it will be possible to make devices to control corresponding electromagnetic waves by creating heaters and diffraction gratings with patterns smaller than the mid- to far-infrared wavelengths. We are developing methods to fabricate thin films, stacks, and microstructures of metal carbides and oxides, and are studying their elemental characteristics.
Research
Materials that are finely processed on a scale of less than the wavelength of electromagnetic waves can control the reflection and transmission of electromagnetic waves (such materials are known as metamaterials). Mid- to far-infrared radiation, with wavelengths ranging from 3 μm to 1000 μm, can be used for the detection of molecules as it is an electromagnetic wave that is related to heat radiation and can excite molecular vibrations. Since it is a heat-related material, being heat-resistant would render it usable for applications that cannot be realized elsewhere. We are studying process technology for heat-resistant materials with various properties such as metal carbides and oxides, and are measuring the fundamental properties of these materials in the infrared region for application to metamaterial design. By fabricating metamaterials for mid- to far-infrared radiation, we aim to create narrow linewidth mid-infrared light emitting devices for molecular detection and materials for controlling radiation heat.
Toshihiro Shimada Professor -
Mass Production of Nanofibrillated Bacterial Cellulose
Bottom-up production of nanofibrillated cellulose from low molecular weight biomass using bacteria
We have acquired a novel cellulose-synthesizing acetic acid bacterium and succeeded in the mass production of nanofibrillated bacterial cellulose (NFBC: Fibnano?) with excellent flowability, miscibility, and formability and that can be used in a wide range of fields, from molasses.
Research
Cellulose synthesized by bacteria and called bacterial cellulose (BC) has unique properties such as high water retention, high strength, biodegradability, and biocompatibility. In recent years, nano-sized cellulose materials (nanofibrillated cellulose (NFC)) has also been attracting attention. In general, NFC is prepared top-down from pulp by physical and chemical treatments, and the resulting NFC is highly dispersed in water. In contrast, by optimizing the culture conditions of cellulose-synthesizing bacteria, it is possible to prepare nanofibrillated BC (NFBC: Fibnano?) from low-molecular biomass in a bottom-up manner. In collaboration with a company in Hokkaido, we have succeeded in the mass production of NFBC (Fibnano?) from molasses, a byproduct of sugar production.
Kenji Tajima Associate ProfessorDoctor of Engineering -
Molecular-level In-situ Optical Observation of Ice Crystal Surfaces
Development of an optical microscope with atomic height resolution and in-situ observation of ice crystal surfaces
In collaboration with Olympus Engineering Corporation, we have developed an optical microscope that has atomic resolution in the height direction. We are now studying mechanisms of the growth, sublimation, and melting of ice crystals at the molecular level.
Research
Crystals bounded by flat surfaces grow layer by layer, irrespective of materials. Therefore, to clarify the mechanisms and kinetics of crystal growth, we need to directly observe the behavior of growing ends of molecular layers (commonly called “elementary step”). However, atomic force microscopes and electron microscopes, both of which are generally used to observe solid surfaces at the molecular level, cannot be used to observe ice crystals. To overcome this difficulty, we have developed an optical microscope that can directly visualize elementary steps with the atomic/molecular height on a flat crystal surface in a non-contact, non-destructive manner. Using this microscope, we are now working on clarifying the growth mechanisms of ice crystals and the melting of ice crystal surfaces at sub-zero temperatures (called “surface melting”) at the molecular level. In addition to ice crystals, we are also conducting a wide range of research to investigate crystal surfaces at the atomic/molecular height levels.
Gen Sazaki Professor -
Monitoring the Output of Renewable Energy Generation and Measures Against Output Fluctuations
Real-time monitoring of fluctuations in solar and wind power output and control of such fluctuations
We have developed a method for extracting load power (A) and renewable energy output (B) from power flow information in which (A) and (B) coexist. Although (B) fluctuates greatly depending on the weather conditions, we have developed a control method to suppress fluctuations using storage batteries and a method to evaluate storage battery capacity.
Research
In this laboratory, we have developed a method to extract the output of renewable energy (RE) power generation hidden in the information of power flowing through distribution lines in real time by applying a signal analysis technique called independent component analysis (ICA). This method enables highly accurate output estimation without having to use preliminary information such as the installed PV capacity in the grid (Fig. 1).
We have also developed a control method to compensate for RE power output fluctuations using storage batteries (Fig. 2) and simulation technology to estimate the storage battery capacity required to suppress output fluctuations for individual wind farms and mega solar power plants.Hiroyuki Kita Professor -
Production of High-purity Sodium
Recycling of sodium resources by electrorefining
There is a sodium-sulfur rechargeable battery that is mainly used for industrial applications. In this research, I am developing a recovery process of metallic sodium from inside of used batteries, and produce high-purity sodium by electrorefining.
Research
This research is for the development of a process of the purification of metallic sodium containing impurities by electrorefining. Metallic sodium from used sodium-sulfur batteries is used as a source material. By placing the metallic sodium in the upper left (anode) of an electrolysis cell model (Fig. 1) and applying current, the sodium ions dissolve in the electrolyte and only the sodium is deposited on the high-purity sodium (cathode) layer on the upper right. This process can be operated at 200°C or less. The high-purity sodium obtained by this electrolysis is pure enough to be used as a raw material for batteries and growth medium of semiconductor crystal. Since Japan is dependent on foreign countries for sodium resources, we believe that this technology will be widely applied in the future.
Mikito Ueda Professor
