The largest Lyapunov exponent and the Lyapunov spectrum of a coupled map lattice are studied when the system state is desynchronous chaos. In the large system size limit a scaling region is found in the parameter spac...The largest Lyapunov exponent and the Lyapunov spectrum of a coupled map lattice are studied when the system state is desynchronous chaos. In the large system size limit a scaling region is found in the parameter space where the largest Lyapunov exponent is independent of the system size and the coupling strength. Some scaling relation between the Lyapunov spectrum distributions for different coupling strengths is found when the coupling strengths are taken in the scaling parameter region. The existence of the scaling domain and the scaling relation of Lyapunov spectra there are heuristically explained.展开更多
In both the construction and operation phases of a repository for high-level radioactive waste, it will be important to constrain groundwater inflow using grouting technology that will be effective under the high grou...In both the construction and operation phases of a repository for high-level radioactive waste, it will be important to constrain groundwater inflow using grouting technology that will be effective under the high groundwater pressure conditions deep underground. In this research, a review of existing grout penetration models in Japan and foreign countries and a trial analysis are conducted with a goal of describing the gout penetration with accuracy on site. Specifically, the applicability of the model developed by Gustafson ＆ Stille to the laboratory penetration tests was studied. The results show that the calculated values from the Gustafson ＆ Stille model agree well with values of laboratory penetration tests.展开更多
This study aims to assess conservation practices in Izta-Popo National Park(Central Mexico) by evaluating the mechanisms of sediment transfer. We applied a methodology based on fallout ^(137)Cs and optically stimulate...This study aims to assess conservation practices in Izta-Popo National Park(Central Mexico) by evaluating the mechanisms of sediment transfer. We applied a methodology based on fallout ^(137)Cs and optically stimulated luminescence(OSL) analysis. This was tested in the upper catchment of Amalacaxco Gorge, selected for being one of the sectors of the park in which man-made actions have been implemented in last decades to favor forest growth in the alpine grassland and to reduce the effect of water runoff. We quantified the ^(137)Cs activity using gamma and beta spectrometry of fine sediment grains extracted from the surface of parcels of 0.4 m2 in areas of natural forest, natural alpine grassland, alpine grassland with conservation practices, ravines and trails. In general, ^(137)Cs values increases as local slope decreases as it was expected. The natural forest is the most stable area in terms of soil erosion and sediment accumulation and, mean ^(137)Cs activity was taken as reference to assess cumulative zones, with higher ^(137)Cs values and erosive, with lower. We found that trails are accumulative surfaces but in other areas, erosion predominates. Man-made ditches, trenches and afforestation in the alpine grassland have higher ^(137)Cs values than thenatural grassland, which indicates that conservation practices are limiting the sediment transfer from hillslopes to channels, however, soil retention is less than in the natural grassland. Additionally, we evaluated the luminescence(OSL) values obtained from samples extracted from the sediment transported in ravines that are cutting into different sectors of the study area to assess the grade of resetting of fluvial materials. These luminescence results indicated that the sediment transported in ravines that are cutting into the natural forest and alpine grassland is bleached more efficiently than the sediment transported in the alpine grassland with conservation practices. Results of fallout ^(137)Cs and luminescence strongly suggest that man-made actions in this part of the Izta-Popo National Park are dramatically modifying the natural mechanisms of sediment transfer and favoring soil erosion. We conclude that made ditches, trenches and afforestation are not an effective conservation practice in Amalacaxco Gorge because they are promoting soil erosion instead of reducing it.展开更多
Commonly proposed concepts, like KBS-3V, for disposal of highly radioactive waste imply construction at medium depth （400-600 m） in granitic rock, which is excellent for constructing a stable repository. VDH （very ...Commonly proposed concepts, like KBS-3V, for disposal of highly radioactive waste imply construction at medium depth （400-600 m） in granitic rock, which is excellent for constructing a stable repository. VDH （very deep boreholes） represent an altemative concept with the advantage that the rock is much less permeable and that the very salt, heavy groundwater is stagnant. Both require engineered barriers in the form of canisters and waste-embedding clay but for somewhat different purposes. Canisters are the most important waste-isolating barriers for KBS-3V but are less important for VDH. The waste-embedding clay is needed for preserving the KBS-3V canisters by being tight and ductile, but plays a minor role for the VDH. The backfilled deposition tunnels in a KBS-3V repository provide very limited hindrance of radionuclides to move to the biosphere while the clay seals of VDH effectively prevent possibly released radionuclides to reach up to the biosphere. Comparison of the KBS-3V and VDH concepts indicates that the last mentioned one has several advantages but that certain issues remain to be worked on for becoming a number one candidate.展开更多
This paper is concerned with a class of semilinear hyperbolic systems in odd space dimensions. Our main aim is to prove the existence of a small amplitude solution which is asymptotic to the free solution as t →-∞ i...This paper is concerned with a class of semilinear hyperbolic systems in odd space dimensions. Our main aim is to prove the existence of a small amplitude solution which is asymptotic to the free solution as t →-∞ in the energy norm, and to show it has a free profile as t →＋∞. Our approach is based on the work of [11]. Namely we use a weighted L^∞ norm to get suitable a priori estimates. This can be done by restricting our attention to radially symmetric solutions. Corresponding initial value problem is also considered in an analogous framework. Besides, we give an extended result of [14] for three space dimensional case in Section 5, which is prepared independently of the other parts of the paper.展开更多
A fundamental understanding of the electrochemical reaction process and mechanism of electrodes is very crucial for developing high-performance electrode materials.In this study,we report the sodium ion storage behavi...A fundamental understanding of the electrochemical reaction process and mechanism of electrodes is very crucial for developing high-performance electrode materials.In this study,we report the sodium ion storage behavior and mechanism of orthorhombic V_(2)O_(5) single-crystalline nanowires in the voltage window of 1.0–4.0 V(vs.Na/Na+).The single-crystalline nanowires exhibit a large irreversible capacity loss during the first discharge/charge cycle,and then show excellent cycling stability in the following cycles.At a current density of 100 mA g^(−1),the nanowires electrode delivers initial discharge/charge capacity of 217/88 mA h g^(−1),corresponding to a Coulombic efficiency of only 40.5%;after 100 cycles,the electrode remains a reversible discharge capacity of 78 mA h g^(−1) with a fading rate of only 0.09%per cycle compared with the 2nd cycle discharge capacity.The sodium ion storage mechanism was investigated,illustrating that the large irreversible capacity loss in the first cycle can be attributed to the initially formed single-crystalline α′-Nax V_(2)O_(5)(0.02<x<0.88),in which sodium ions cannot be electrochemically extracted and the α′-Na0.88 V_(2)O_(5) can reversibly host and release sodium ions via a single-phase(solid solution)reaction,leading to excellent cycling stability.The Na^(+) diffusion coefficient in α′-Nax V_(2)O_(5) ranges from 10^(−12) to 10^(−11.5) cm^(2) s^(−1) as evaluated by galvanostatic intermittent titration technique(GITT).展开更多
文摘The largest Lyapunov exponent and the Lyapunov spectrum of a coupled map lattice are studied when the system state is desynchronous chaos. In the large system size limit a scaling region is found in the parameter space where the largest Lyapunov exponent is independent of the system size and the coupling strength. Some scaling relation between the Lyapunov spectrum distributions for different coupling strengths is found when the coupling strengths are taken in the scaling parameter region. The existence of the scaling domain and the scaling relation of Lyapunov spectra there are heuristically explained.
文摘In both the construction and operation phases of a repository for high-level radioactive waste, it will be important to constrain groundwater inflow using grouting technology that will be effective under the high groundwater pressure conditions deep underground. In this research, a review of existing grout penetration models in Japan and foreign countries and a trial analysis are conducted with a goal of describing the gout penetration with accuracy on site. Specifically, the applicability of the model developed by Gustafson ＆ Stille to the laboratory penetration tests was studied. The results show that the calculated values from the Gustafson ＆ Stille model agree well with values of laboratory penetration tests.
文摘This study aims to assess conservation practices in Izta-Popo National Park(Central Mexico) by evaluating the mechanisms of sediment transfer. We applied a methodology based on fallout ^(137)Cs and optically stimulated luminescence(OSL) analysis. This was tested in the upper catchment of Amalacaxco Gorge, selected for being one of the sectors of the park in which man-made actions have been implemented in last decades to favor forest growth in the alpine grassland and to reduce the effect of water runoff. We quantified the ^(137)Cs activity using gamma and beta spectrometry of fine sediment grains extracted from the surface of parcels of 0.4 m2 in areas of natural forest, natural alpine grassland, alpine grassland with conservation practices, ravines and trails. In general, ^(137)Cs values increases as local slope decreases as it was expected. The natural forest is the most stable area in terms of soil erosion and sediment accumulation and, mean ^(137)Cs activity was taken as reference to assess cumulative zones, with higher ^(137)Cs values and erosive, with lower. We found that trails are accumulative surfaces but in other areas, erosion predominates. Man-made ditches, trenches and afforestation in the alpine grassland have higher ^(137)Cs values than thenatural grassland, which indicates that conservation practices are limiting the sediment transfer from hillslopes to channels, however, soil retention is less than in the natural grassland. Additionally, we evaluated the luminescence(OSL) values obtained from samples extracted from the sediment transported in ravines that are cutting into different sectors of the study area to assess the grade of resetting of fluvial materials. These luminescence results indicated that the sediment transported in ravines that are cutting into the natural forest and alpine grassland is bleached more efficiently than the sediment transported in the alpine grassland with conservation practices. Results of fallout ^(137)Cs and luminescence strongly suggest that man-made actions in this part of the Izta-Popo National Park are dramatically modifying the natural mechanisms of sediment transfer and favoring soil erosion. We conclude that made ditches, trenches and afforestation are not an effective conservation practice in Amalacaxco Gorge because they are promoting soil erosion instead of reducing it.
文摘Commonly proposed concepts, like KBS-3V, for disposal of highly radioactive waste imply construction at medium depth （400-600 m） in granitic rock, which is excellent for constructing a stable repository. VDH （very deep boreholes） represent an altemative concept with the advantage that the rock is much less permeable and that the very salt, heavy groundwater is stagnant. Both require engineered barriers in the form of canisters and waste-embedding clay but for somewhat different purposes. Canisters are the most important waste-isolating barriers for KBS-3V but are less important for VDH. The waste-embedding clay is needed for preserving the KBS-3V canisters by being tight and ductile, but plays a minor role for the VDH. The backfilled deposition tunnels in a KBS-3V repository provide very limited hindrance of radionuclides to move to the biosphere while the clay seals of VDH effectively prevent possibly released radionuclides to reach up to the biosphere. Comparison of the KBS-3V and VDH concepts indicates that the last mentioned one has several advantages but that certain issues remain to be worked on for becoming a number one candidate.
基金Project supported by Grant-in-Aid for Science Research (No.12740105, No.14204011), JSPS.
文摘This paper is concerned with a class of semilinear hyperbolic systems in odd space dimensions. Our main aim is to prove the existence of a small amplitude solution which is asymptotic to the free solution as t →-∞ in the energy norm, and to show it has a free profile as t →＋∞. Our approach is based on the work of [11]. Namely we use a weighted L^∞ norm to get suitable a priori estimates. This can be done by restricting our attention to radially symmetric solutions. Corresponding initial value problem is also considered in an analogous framework. Besides, we give an extended result of [14] for three space dimensional case in Section 5, which is prepared independently of the other parts of the paper.
基金financially supported by the National Natural Science Foundation of China (51664012)Guangxi Natural Science Foundation (2017GXNSFAA198117 and2015GXNSFGA139006)the Technology Major Project of Guangxi(AA19046001)
文摘A fundamental understanding of the electrochemical reaction process and mechanism of electrodes is very crucial for developing high-performance electrode materials.In this study,we report the sodium ion storage behavior and mechanism of orthorhombic V_(2)O_(5) single-crystalline nanowires in the voltage window of 1.0–4.0 V(vs.Na/Na+).The single-crystalline nanowires exhibit a large irreversible capacity loss during the first discharge/charge cycle,and then show excellent cycling stability in the following cycles.At a current density of 100 mA g^(−1),the nanowires electrode delivers initial discharge/charge capacity of 217/88 mA h g^(−1),corresponding to a Coulombic efficiency of only 40.5%;after 100 cycles,the electrode remains a reversible discharge capacity of 78 mA h g^(−1) with a fading rate of only 0.09%per cycle compared with the 2nd cycle discharge capacity.The sodium ion storage mechanism was investigated,illustrating that the large irreversible capacity loss in the first cycle can be attributed to the initially formed single-crystalline α′-Nax V_(2)O_(5)(0.02<x<0.88),in which sodium ions cannot be electrochemically extracted and the α′-Na0.88 V_(2)O_(5) can reversibly host and release sodium ions via a single-phase(solid solution)reaction,leading to excellent cycling stability.The Na^(+) diffusion coefficient in α′-Nax V_(2)O_(5) ranges from 10^(−12) to 10^(−11.5) cm^(2) s^(−1) as evaluated by galvanostatic intermittent titration technique(GITT).
