PHEBUS DILUTED IMPACTOR QUALIFICATION EXPERIMENTS
0
Citation
2
Reference
10
Related Paper
Moderate-resolution imaging spectroradiometer
Spectroradiometer
Cite
Citations (230)
Despite covering only 2–6% of land, wetland ecosystems play an important role at the local and global scale. They provide various ecosystem services (carbon dioxide sequestration, pollution removal, water retention, climate regulation, etc.) as long as they are in good condition. By definition, wetlands are rich in water ecosystems. However, ongoing climate change with an ambiguous balance of rain in a temperate climate zone leads to drought conditions. Such periods interfere with the natural processes occurring on wetlands and restrain the normal functioning of wetland ecosystems. Persisting unfavorable water conditions lead to irreversible changes in wetland habitats. Hence, the monitoring of habitat changes caused by an insufficient amount of water (plant water stress) is necessary. Unfortunately, due to the specific conditions of wetlands, monitoring them by both traditional and remote sensing techniques is challenging, and research on wetland water stress has been insufficient. This paper describes the adaptation of the thermal water stress index, also known as the crop water stress index (CWSI), for wetlands. This index is calculated based on land surface temperature and meteorological parameters (temperature and vapor pressure deficit—VPD). In this study, an unmanned aerial system (UAS) was used to measure land surface temperature. Performance of the CWSI was confirmed by the high correlation with field measurements of a fraction of absorbed photosynthetically active radiation (R = −0.70) and soil moisture (R = −0.62). Comparison of the crop water stress index with meteorological drought indices showed that the first phase of drought (meteorological drought) cannot be detected with this index. This study confirms the potential of using the CWSI as a water stress indicator in wetland ecosystems.
Cite
Citations (31)
Land surface variables such as surface soil moisture are recognized as important wildfire indicators. However, quantifying wildfire fuel combustibility through only satellite-retrieved soil moisture remains challenging, because soil moisture does not provide information about vegetation (fuel) moisture and water availability to plants is complicated by another factor of soil properties. Thus, to enhance the wildfire prediction ability of the soil moisture active passive (SMAP) mission, this study examines a canopy stress index (CSI) retrieved from 1 km SMAP level 2 products. The strong relationship between prefire CSI and fire severity is demonstrated over two large-scale (greater than 1000 ha) wildfires in Gang-won Province, South Korea. CSI can effectively predict the severity of large-scale wildfires one week before fire events, differentiating dry soils from wildfire hazards. SMAP L2 data with a temporal resolution of 5–7 d over the study sites are suitable for supporting aerial firefighting activities and reducing false fire warnings.
Combustibility
Cite
Citations (17)
Biomanipulation
Cite
Citations (89)
Soil moisture impacts the biosphere–atmosphere exchange of CO2 and CH4 and plays an important role in the terrestrial carbon cycle. A better representation of soil moisture would improve coupled carbon–water dynamics in terrestrial ecosystem models and could potentially improve model estimates of large-scale carbon fluxes and climate feedbacks. Here, we investigate using soil moisture observations from the Soil Moisture Active Passive (SMAP) satellite mission to inform simulated carbon fluxes in the global terrestrial ecosystem model LPJ-wsl. Results suggest that the direct insertion of SMAP reduces the bias in simulated soil moisture at in situ measurement sites by 40%, with a greater improvement at temperate sites. A wavelet analysis between the model and measurements from 26 FLUXNET sites suggests that the assimilated run modestly reduces the bias of simulated carbon fluxes for boreal and subtropical sites at 1–2-month time scales. At regional scales, SMAP soil moisture can improve the estimated responses of CO2 and CH4 fluxes to extreme events such as the 2018 European drought and the 2019 rainfall event in the Sudd (Southern Sudan) wetlands. The simulated improvements to land–surface carbon fluxes using the direct insertion of SMAP are shown across a variety of timescales, which suggests the potential of SMAP soil moisture in improving the model representation of carbon–water coupling.
Soil carbon
Terrestrial ecosystem
Water cycle
Cite
Citations (9)
In a Deuterium-Tritium fusion reactor, nearly 20% of the thermal power has to be transferred from the hot plasma through the wall components of the burn chamber. Design requirements of commercial fusion power plant in-vessel components are potentially even more stringent than those of experimental devices. Fusion nuclear reactor studies are currently devoted mostly to the Deuterium-Tritium (DT) fuel cycle, since it is the easiest way to reach ignition or a high energy gain. However, reducing the activation of materials is one of the biggest concerns for fusion power: the study of advanced fuel fusion devices, such as the CANDOR Deuterium-Helium-3 (DHe3) tokamak, is proposed for this purpose. The plasma confinement requirements for a DHe3 reactor are much more challenging than those for a DT reactor. Thus, the demands on the divertor and the first wall are more severe, particularly during a disruption. Safety analyses, starting from heat load determinations, have been performed for CANDOR, a proposed DHe3 experiment, starting from similar evaluations carried out for the ARIES III DHe3 reactor.
Fusion power
Cite
Citations (2)
Abstract One of the potential impacts of global warming is likely to be experienced through changes in flood frequency and magnitude, which poses a potential threat to the downstream reservoir flood control system. In this paper, the downscaling results of the multimodel dataset from phases 3 and 5 of the Coupled Model Intercomparison Project (CMIP3 and CMIP5, respectively) were coupled with the Variable Infiltration Capacity (VIC) model to evaluate the impact of climate change on the Feilaixia reservoir flood control in the Beijiang River basin for the first time. Four emissions scenarios [A1B and representative concentration pathway (RCP) scenarios RCP2.6, RCP4.5, and RCP8.5] were chosen. Results indicate that annual distribution and interannual variability of temperature and precipitation are well simulated by the downscaling results of the CMIP3 and CMIP5 multimodel dataset. The VIC model, which performs reasonably well in simulating runoff processes with high model efficiency and low relative error, is suitable for the study area. Overall, annual maximum 1-day precipitation in 2020–50 would increase under all the scenarios (relative to the baseline period 1970–2000). However, the spatial distribution patterns of changes in projected extreme precipitation are uneven under different scenarios. Extreme precipitation is most closely associated with extreme floods in the study area. There is a gradual increase in extreme floods in 2020–50 under any of the different emission scenarios. The increases in 500-yr return period daily discharge of the Feilaixia reservoir have been found to be from 4.35% to 9.18% in 2020–50. The reservoir would be likely to undergo more flooding in 2020–50.
Flood control
Representative Concentration Pathways
Cite
Citations (45)
Ten-year water quality,eutrophication condition and main pollution indices in Taihu Lake were analyzed using monitoring data from 1997 to 2006.The results show that Taihu Lake was mostly polluted by organic matter,and water quality deteriorated with eutrophication.Great effort is needed to control water pollution in Taihu Lake.
Cite
Citations (9)
AbstractThe Very High Temperature Gas-Cooled Reactor (VHTR) is one of the next-generation nuclear reactors designed to achieve high temperatures to support industrial applications and power generation. Because of the high temperature reached during normal operation, new safety features were added to its design. The reactor cavity cooling system (RCCS) is a passive safety system that will be incorporated in the VTHR. The system was designed to remove the heat from the reactor cavity and maintain the temperature of structures and concrete walls under desired limits during normal operation (steady state) and accident scenarios. A small-scale (1:23) water-cooled experimental facility was scaled, designed, and constructed in order to study the thermal-hydraulic phenomena taking place in the RCCS during steady-state and transient conditions. The facility represents a portion of the reactor vessel with nine stainless steel coolant risers and utilizes water as coolant. The facility was equipped with instrumentation to measure temperatures and flow rates. A steady-state experimental run was conducted to study the behavior of the coolant under this condition. The experimental results obtained confirmed the capabilities of the system in removing the heat from the cavity and helped in identifying phenomena that may occur in this type of passive system.
Transient (computer programming)
Thermal hydraulics
Decay heat
Instrumentation
Pressurizer
Heat Generation
Natural circulation
Cite
Citations (18)
The High Temperature Engineering Test Reactor (HTTR) of the Japan Atomic Energy Agency (JAEA) is a 30 MWth, graphite-moderated, helium-cooled reactor that was constructed with the objectives to establish and upgrade the technological basis for advanced high-temperature gas-cooled reactors (HTGRs) as well as to conduct various irradiation tests for innovative high-temperature research. The core size of the HTTR represents about one-half of that of future HTGRs, and the high excess reactivity of the HTTR, necessary for compensation of temperature, xenon, and burnup effects during power operations, is similar to that of future HTGRs. During the start-up core physics tests of the HTTR, various annular cores were formed to provide experimental data for verification of design codes for future HTGRs. The experimental benchmark performed and currently evaluated in this report pertains to the data available for two zero-power, warm-critical measurements with the fully-loaded HTTR core. Six isothermal temperature coefficients for the fully-loaded core from approximately 340 to 740 K have also been evaluated. These experiments were performed as part of the power-up tests (References 1 and 2). Evaluation of the start-up core physics tests specific to the fully-loaded core (HTTR-GCR-RESR-001) and annular start-up core loadings (HTTR-GCR-RESR-002) have been previously evaluated.
Burnup
Cite
Citations (5)