Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-04-10
LIN Shen
SONG Luyang
SU Jun
CHEN Xin
SHEN Zhilin
ZHANG Hao
SHENG Yaode
ZHANG Liyong
HE Jianjun
CHEN Size
SHEN Yangping
JIN Shilun
LU Fei
XIAO Dan
ZHANG Yong
NAN Wei
JIANG Yuchen
ZHANG Yuqiang
ZHANG Yang
TIAN Junwen
Abstract： In thermonuclear reactions of nuclear astrophysical interest, some can produce short-lived products that emit positrons. The positrons emitted by these products will annihilate with electrons in the target and then produce a pair of 511 keV γ-rays, which can be used to determine the reaction yield and calculate the cross-section as well as the astrophysical S-factor. Recently, it has been found that the spatial coincidence measurements can be performed basing on the opposite direction of the 511 keV-511 keV γ-ray pair, which can reduce the natural background and enables the in situ measurement of the reaction yield using activity method. In this paper, based on the recently developed large modular BGO detector array LAMBDA-II, this method has been investigated and validated in the ground laboratory, which provides good basis for further application of this method in the nuclear astrophysical investigations in the future.
Peer Review Status:
Awaiting Review
Subjects: Library Science，Information Science >> Library Science submitted time 2023-08-27 Cooperative journals: 《图书情报工作》
Abstract： [Purpose/significance] Bibliometrics, Scientometrics, Informetrics, Webometrics and Knowledgometrics are known as Five Metrics and the important aspect of information science. The analysis of Five Metrics is conducive to the further development of the metric research through literature theme and quantitative analysis. This paper carefully summaries the evolution process and condition of Five Metrics in China in order to provide guidance for further research.[Method/process] This paper designs Six-dimensional framework and conducts research on data from scientific payoffs, scientific research fund, course education, talents and organization, scientific evaluation and software tools. Besides, this paper draws thematic evolution map through Citespace to analyze evolutionary process and development status of each branch of Five Metrics.[Result/conclusion] The conclusions of this paper are:a) Chinese influence in Five Metrics are increasing, and data collection according to six-dimensional framework shows an advancing trend; b) Chinese Five Metrics research are more innovative than before, more attention has been paid to methodology and application, and Chinese database and software have been designed; c) Five Metrics in China shows a characteristic of subject overlapping, including imitation and application of other subjects; d) The objects of Five Metric are gradually enriching; e) The unit of metrics is more fine-grained from bibliography to knowledge.
Subjects: Biology >> Botany >> Applied botany submitted time 2022-05-21 Cooperative journals: 《广西植物》
Abstract： To improve our understanding of farmland surface process and agricultural water management in arid oasis area, we analyzed the characteristics of water and heat fluxes at different time scales, and the influence of arid advection and canopy conductance (Gc) on water and heat fluxes at different growth stages. In addition, we used path analysis to study the influence path of environmental factors on latent heat flux (LE). In this paper, the water and heat fluxes were measured by eddy-covariance in 2017. The results were as follows: (1) LE showed multiple peaks, while the other fluxes were basically unimodal shapes at the daily scale. On the whole, the values of daily net radiation (Rn) were maximum, followed by LE, sensible heat flux (H) and soil heat flux (G) at each growth stage. The variation of diurnal G showed obvious lagged effect compared to that of Rn. (2) LE and H accounted for 86% and 14% (respectively) of daytime energy during the whole growing stages, indicating that LE was the main energy consumption item. The contribution of arid advection to daytime LE ranged from 5% to 59% with an average value of 28% at whole growing season. The influence of Gc on LE was stronger at the new shoot and leaf-fall stages than that in the middle growing season. (3) LE was mainly affected by Rn, followed by vapor pressure deficit (VPD) and air temperature (Ta), and the influence degree of VPD and Ta on LE was similar. Furthermore, the path analysis showed that Rn directly affected LE; VPD and Ta mainly affected LE indirectly through Rn. As a whole, the water and heat fluxes in vineyards of arid desert oasis in Northwest China display significant diurnal and seasonalvariations, and the influences of environmental factors on these exists great discrepancies in magnitude and path.
Subjects: Biology >> Botany >> Applied botany submitted time 2022-03-18 Cooperative journals: 《广西植物》
Abstract： Grapes are one of the main economic crops in the arid area of Northwest China. Understanding its photosynthetic production process is very important for planting and cultivation. In order to analyze the physiological characteristics of grape photosynthesis and the main influencing factors affecting grape photosynthesis under natural conditions in the field, the daily variation of net photosynthetic rate of grape (variety: Seedless White) leaves and its daily variation of physiological and ecological factors in typical season of grape were measured from June to September in 2019. The path analysis method is used to analyze the direct and indirect effects of various factors on the net photosynthetic rate of grape leaves, and determine its main influencing factors. In addition, the response of the net photosynthetic rate of grape leaves to various physiological and ecological factors was further analyzed in the whole day time-phased mode. The results were as follows: (1) The daily variation of net photosynthetic rate of grape leaves showed a single peak pattern, which first increased and then decreased; (2) The net photosynthetic rate of grape leaves was positively correlated with photosynthetic active radiation, vapor pressure difference, air temperature, stomatal conductance and transpiration rate, and negatively correlated with relative humidity and intercellular CO2 concentration. Among them, the correlation coefficient with stomatal conductance and transpiration rate is the largest.; (3) The main determinant that affected the variation of net photosynthetic rate of grape leaves is the transpiration rate in July, August and September, and the stomatal conductance in June; (4) The net photosynthetic rate of grape leaves in each month showed a “hysteretic loop” relationship with ecological factors air temperature, photosynthetic active radiation, vapor pressure deficit, and a good linear relationship with physiological factors transpiration rate and stomatal conductance (R2>0.85), and an exponential function relationship with intercellular CO2 concentration (R2=0.53). Studies have shown that grapes have a strong ability to adapt to the environment in the arid area of Northwest China. In cultivation, we can optimize management and increase yield by controlling transpiration rate and stomatal conductance, but the direct and indirect effects of other factors need to be considered.
Subjects: Geosciences >> Geography submitted time 2021-06-13 Cooperative journals: 《干旱区研究》
Abstract：研究干旱区绿洲农业生态系统碳收支动态和其碳源汇形成机制对于指导绿洲农业固碳减排至关重要。基于敦煌干旱绿洲葡萄园涡度相关系统观测的CO2通量和相关环境因子数据，估算2019年生长季（5—10月）葡萄园的碳收支总量，同时探究净生态系统碳交换（NEE）的日、季动态及其对叶面积指数（LAI）、光合有效辐射（PAR）、水汽压差（VPD）和空气温度（Ta）等的响应。结果表明：（1）生长季期间，葡萄园净生态系统碳交换（NEE）、生态系统呼吸（Re）和总初级生产力（GPP）的累计量分别为-647.3、883.2 g C·m-2和1530.5 g C·m-2，Re/GPP值为57.7%，表明其碳消耗强度较低，为强烈的碳汇过程。（2）生长季NEE量变化呈单峰型（7月峰值），与空气温度的季节变化相似。这表明在水分供应充足的基本条件下，空气温度对于NEE具有显著影响。（3）生长季NEE受到LAI、PAR、VPD、Ta等生物物理因素的综合作用，在整个生长季PAR是与其相关性最高的环境因子，通过驱动光合作用增加固碳量；生长季LAI先增加后减少，光合固碳量也相应受到影响，进而造成NEE呈先下降后上升趋势。同时，保持VPD处于适宜的范围（20~35 hPa），可有效地提高其固碳能力。
Subjects: Geosciences >> Other Disciplines of Geosciences submitted time 2019-09-09 Cooperative journals: 《干旱区研究》
Abstract：根据新疆北部40个站点1961—2016年逐日气温、降水数据，采用数理统计、倾向率法、Mann-Kendall突变检验和小波分析等方法，研究北疆地区近56 a气候变化特征、变化趋势以及变化的空间差异。结果表明：在研究时段内，气候总体呈气温升高、降水量增加的暖湿化趋势，年平均气温以0.34 ℃·(10a)-1速率上升，年降水量递增速率12.05 mm·(10a)-1；Mann-Kendall突变检验显示，气温在1991年发生突变后升高，降水量1987年出现突变后逐渐增多；年平均气温变化表现出6 a、14 a和28 a周期性规律，降水量变化有4 a、12 a和22 a的规律；在空间上，气温增速东西大于南北，降水量增量山区多于平原和盆地，西部多于东部。
Subjects: Geosciences >> Other Disciplines of Geosciences submitted time 2019-09-09 Cooperative journals: 《干旱区研究》
Abstract：根据新疆北部40个站点1961—2016年逐日气温、降水数据，采用数理统计、倾向率法、Mann-Kendall突变检验和小波分析等方法，研究北疆地区近56 a气候变化特征、变化趋势以及变化的空间差异。结果表明：在研究时段内，气候总体呈气温升高、降水量增加的暖湿化趋势，年平均气温以0.34 ℃·(10a)-1速率上升，年降水量递增速率12.05 mm·(10a)-1；Mann-Kendall突变检验显示，气温在1991年发生突变后升高，降水量1987年出现突变后逐渐增多；年平均气温变化表现出6 a、14 a和28 a周期性规律，降水量变化有4 a、12 a和22 a的规律；在空间上，气温增速东西大于南北，降水量增量山区多于平原和盆地，西部多于东部。
Subjects: Dynamic and Electric Engineering >> Engineering Thermophysics submitted time 2017-11-23 Cooperative journals: 《工程热物理学报》
Abstract：为了揭示端壁装配缝几何参数对叶片尾缘下游部分的气膜冷却特性影响机理，本文对GE-E3直列叶栅中的装配缝气膜冷却特性进行了数值模拟研究。研究发现槽缝几何参数对叶片尾缘的冷却特性具有较大影响。装配缝两侧端壁中，靠近吸力面端壁高于另一侧端壁对提高端壁气膜有效度具有有利作用。双侧切角结构虽然提高了靠近装配缝区域的气膜有效度，但增大了冷却盲区。装配缝结构应以靠近吸力侧偏高的几何关系和提高冷却出流速度为目标进行设计和优化。
Subjects: Dynamic and Electric Engineering >> Engineering Thermophysics submitted time 2017-10-30 Cooperative journals: 《工程热物理学报》
Abstract：为了揭示端壁装配缝几何参数对叶片尾缘下游部分的气膜冷却特性影响机理，本文对GE-E3直列叶栅中的装配缝气膜冷却特性进行了数值模拟研究。研究发现槽缝几何参数对叶片尾缘的冷却特性具有较大影响。装配缝两侧端壁中，靠近吸力面端壁高于另一侧端壁对提高端壁气膜有效度具有有利作用。双侧切角结构虽然提高了靠近装配缝区域的气膜有效度，但增大了冷却盲区。装配缝结构应以靠近吸力侧偏高的几何关系和提高冷却出流速度为目标进行设计和优化。
Hits
Hits
Downloads
Comment