摘要 :
A number of authors have recently pointed out inconsistencies of results obtained with the Huang-Yang multipolar pseudopotential for low-energy scattering [K. Huang and K. C. Yang, Phys. Rev. 105, 767 (1957); later revised by Huan...
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A number of authors have recently pointed out inconsistencies of results obtained with the Huang-Yang multipolar pseudopotential for low-energy scattering [K. Huang and K. C. Yang, Phys. Rev. 105, 767 (1957); later revised by Huang, Statistical Mechanics (Wiley, New York, 1963)]. The conceptual validity of their original derivation has been questioned. Here I show that these inconsistencies are rather due to an algebraic mistake made by Huang and Yang. With the corrected error, I present the revised version of the multipolar pseudopotential.
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As one of the main driving forces for the change in surface energy balance, land use and cover change affects the ecological climate through different levels of biogeochemical and physical processes. However, many studies on the s...
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As one of the main driving forces for the change in surface energy balance, land use and cover change affects the ecological climate through different levels of biogeochemical and physical processes. However, many studies on the surface energy balance are conducted from the perspective of biogeochemistry, ignoring biogeochemical processes. By using core methods such as the surface energy balance algorithm and Mann-Kendall trend test, we analyzed the surface energy balance mechanism and ecological climate effects of five land use types in the Huang-Huai-Hai Basin in China. The results showed that (1) the net radiation and latent heat flux in the five land use types increased significantly, and their highest values were located in cropland areas and urban expansion areas, respectively. (2) The influence of net radiation on surface energy absorption was greater than latent heat flux. This relationship was more obvious in land use types that were greatly influenced by human activities. (3) The net surface energy intake in the Huang-Huai-Hai River Basin showed a decreasing trend and decreased with the increase in human influence intensity, indicating that human activities weakened the positive trend in net surface energy intake and increased the warming effect. This study reveals the difference in energy budgets of different land use types under the influence of human activities. It is helpful for understanding how to formulate sustainable land management strategies, and it also provides a theoretical basis for judging the climate change trends and urban heat island effects in the Huang-Huai-Hai River Basin from a biogeophysical perspective.
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Drought is a major natural hazard that can have devastating impacts on regional agriculture, water resources and the environment. To assess the variability and pattern of drought characteristics in the Huang-Huai-Hai (HHH) Plain, ...
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Drought is a major natural hazard that can have devastating impacts on regional agriculture, water resources and the environment. To assess the variability and pattern of drought characteristics in the Huang-Huai-Hai (HHH) Plain, the daily Standardized Precipitation Evapotranspiration Index (SPEI) is developed based on daily meteorological data in this study. The daily SPEI data are used, including Annual Total Drought Severity (ATDS), Annual Total Drought Duration (ATDD) and Annual Drought Frequency (ADF), which were calculated from 1981 to 2010 at 28 meteorological stations. We used the indices (ATDS, ATDD and ADF), Hovmoller diagrams and the reliable no parameter statistical methods of the Mann-Kendall test to assess the variability and pattern of drought characteristics for the period from 1981 to 2010 in the HHH plain. The results suggested that severe drought occurred in the 1980s, the late 1990s and the early 2000s, severe drought events occurred in 1981, 1986, 1997 and 2002. Decreasing trends for both ATDS and ATDD were found, and the drought situation did not worsen under global warming during the past 30 years, and the drought situation is alleviating in the entire HHH plain. The northeast and southwest regions of the HHH plain have suffered from more severe drought, and the north region is prone to drought. The results of the study can provide a scientific understanding for the adoption of countermeasures of regional defence against drought and also may serve as a reference point for drought hazard vulnerability analysis.
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Huang-huai-hai River basin is an important grain production area and economic zone of China. Under the impact of global warming, energy resources are changing all around the world. Studying the ≥ 10 °C accumulated temperature (A...
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Huang-huai-hai River basin is an important grain production area and economic zone of China. Under the impact of global warming, energy resources are changing all around the world. Studying the ≥ 10 °C accumulated temperature (AT10) is of great importance for the food security and economy of Huang-huai-hai River basin. The slope of AT10 and Mann-Kendall statistical test were applied to quantify the trend magnitude and detect the significant trend respectively. And the distribution pattern and movement characteristics had been analysed with GIS technology. The results shown that AT 10 of Huang-huai-hai River basin has an increasing trend during since 1960s; AT 10 has a moving tendency towards the northwest and decreased from the southeast region towards the northwest region. The ratio between active area and stable area in different classes has fluctuated during the study period.
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The biggest load of water resources for agricultural economy in the Huang-Hai plain will only account for 67.1/100 of the forecasted irrigated area in 2010. The irrigated area and the quantily of water diverting from the Huanghe R...
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The biggest load of water resources for agricultural economy in the Huang-Hai plain will only account for 67.1/100 of the forecasted irrigated area in 2010. The irrigated area and the quantily of water diverting from the Huanghe River was 2.2 million hm~2 and 10.8 billion m~3 respectively in the lower reaches of the river in the 1990s. The annual amount of yield increase for grain is 6.3 billion kg calculated by converting and the annual benefit of yield-increase is 4.4 billion RMB yuan in the irrigated area of the region.
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Extreme climate events and related risk exposures in Huang-Huai-Hai (HHH) river basin were projected under global warming of 1.5-2 degrees C using the high-resolution combined dynamical and statistical downscaling dataset. Firstly...
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Extreme climate events and related risk exposures in Huang-Huai-Hai (HHH) river basin were projected under global warming of 1.5-2 degrees C using the high-resolution combined dynamical and statistical downscaling dataset. Firstly, evaluation indicated that the dataset can well reproduce the spatial distribution of all temperature extremes and most of the precipitation extremes, providing a reliable ability for future projections. Then, projections showed that the hot events were projected to increase, while the cold events were projected to decrease substantially in the whole HHH river basin for 1.5 degrees C and 2 degrees C global warming. The additional 0.5 degrees C of warming roughly accelerated the increase of extreme temperatures by 0.6 degrees C, and increased the number of heat days by 2.7 days. In addition, the rainfall events and the precipitation intensity were projected to increase while the drought events were projected to decrease, with the slight changes due to the additional 0.5 degrees C warming. The gross domestic product (GDP) exposures to heat events and heavy rainfall increased more than nine fold for 1.5 degrees C and 2 degrees C global warming, while the growing population (POP) exposures to that increased by more than 100% and 20%, respectively. For the increased exposures to heat events, the changes in GDP (POP) were as important as changes in interaction effect between climate and GDP (POP), while the exposures to heavy rainfall events was mainly dominated by GDP (POP). In addition, the enhanced interaction effect was the most important factor to the increase of exposures due to additional 0.5 degrees C of warming. Notably, the largest increases of heat events and heavy rainfall events were projected in Huaihe river basin due to the additional 0.5 degrees C warming, accompanied by greatest increase of exposures, implying larger risk in the future.
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We observe monopole oscillations in a mixture of Bose-Einstein condensates, where the usually dominant mean-field interactions are canceled. In this case, the system is governed by the next-order Lee-Huang-Yang (LHY) correction to...
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We observe monopole oscillations in a mixture of Bose-Einstein condensates, where the usually dominant mean-field interactions are canceled. In this case, the system is governed by the next-order Lee-Huang-Yang (LHY) correction to the ground state energy, which describes the effect of quantum fluctuations. Experimentally such a LHY fluid is realized by controlling the atom numbers and interaction strengths in a K-39 spin mixture confined in a spherical trap potential. We measure the monopole oscillation frequency as a function of the LHY interaction strength as proposed recently by Jrgensen et al. [Phys. Rev. Lett. 121, 173403 (2018)] and find excellent agreement with simulations of the complete experiment including the excitation procedure and inelastic losses. This confirms that the system and its collective behavior are initially dominated by LHY interactions. Moreover, the monopole oscillation frequency is found to be stable against variations of the involved scattering lengths in a broad region around the ideal values, confirming the stabilizing effect of the LHY interaction. These results pave the way for using the nonlinearity provided by the LHY term in quantum simulation experiments and for investigations beyond the LHY regime.
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Drought has become one of the most serious meteorological disasters for agricultural production in many areas around the world, and the situation could be worse under the impact of climate change. To facilitate better adaptation p...
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Drought has become one of the most serious meteorological disasters for agricultural production in many areas around the world, and the situation could be worse under the impact of climate change. To facilitate better adaptation planning, this study proposed a drought assessment framework integrating downscaling method, drought index, copula technique, and bivariate frequency analysis, and applied it to investigate the change of the drought characteristics and drought risks from the past to the future in Huang-Huai-Hai River basin (HRB), North China. Drought was firstly defined by standardized precipitation evapotranspiration index (SPEI) based on 1497 observed grid data from 1979 to 2004. Then, we constructed the joint distribution of drought duration and severity based on copulas to detect and quantify the drought risks. To address the effect of climate change, similar calculation process was applied to the future climate data, which was downscaled using delta change method from representative concentration pathway (RCP 8.5) of 12 general circulation models (GCMs). The study results suggested that, under climate change condition, most irrigation districts over HRB would generally experience lower frequency of drought events but with extended duration; some districts would have more serious drought, but majority would experience similar or even lower level of severity. In light of the mean joint occurrence probability, the irrigation district at the south part of Huai River basin would likely experience the highest increase of drought risks in near future (by 0.86%) and distant future (by 0.76%), while most of other districts over HRB would face low risk of serious drought risks. The obtained results offer useful information to agricultural managers or water resources authorities who are interested in the development of effective long-term adaptation strategies for drought management.
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Water resources play a principal role in supporting environment. Climate change will challenge the current water resources management practices and threaten water security through acceleration of the hydrological cycle. Historical...
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Water resources play a principal role in supporting environment. Climate change will challenge the current water resources management practices and threaten water security through acceleration of the hydrological cycle. Historical variation of recorded runoff on main streams and influence of climate change on water resources in the Huang-huai-hai area (including the Yellow River, Hai River, and the Huai River) were analyzed with statistical methods and a hydrological simulation approach. Results indicate that the recorded runoff showed a significant decreasing trend during past 50 years for the Hai River and the middle and lower reaches of the Yellow River, with insignificant change occurring in the Huai River basin and the upstream of the Yellow River basin. Temperature was projected to steadily rise in the next 30-50 years while precipitation was expected to increase slightly. Water resources in 2021-2050 under the three scenarios of RCP2.6, RCP4.5, and RCP8.5 were estimated to change -1.3%, 1.0% and -2.3% relative to the reference period of 1961-1990, respectively. The water shortage for the Huang-huai- hai area might be aggravated due to climate change. It is therefore of significance to enhance water saving construction, make full use of non- traditional water sources, and speed up water conservancy project planning and implementation for adaptation to climate change. (C) 2015 Elsevier Ltd and INQUA. All rights reserved.
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