Subjects: Physics >> Nuclear Physics submitted time 2024-01-10
FU Chaoyi
LI Hongfu
SUN Mingze
XING Yuanming
YAN Xinliang
ZHAO Jiankun
ZHOU Xu
PENG Tingwei
ZENG Qi
WANG Meng
ZHANG Yuhu
TU Xiaolin
Abstract： The Lanzhou Heavy Ion Accelerator Cooling Storage Ring(HIRFL-CSR) is an ideal device for studying the decay of highly charged and short-lived isomers. In the lifetime measurement experiment of the short-lived highly charged ion 94mRu44+, we directly observed the decay of 94Ru from 8+ isomer to the ground state, and identified 49 decay events in the observation time window of (20 μs, 180 μs). In order to identify more decay events, a method based on spectral amplitude was studied in this paper. Based on the simulation results, this method can effectively identify decay events within (15 μs, 185 μs). By applying the new identification method to the experimental data processing, 54 decay events were identified within (15 μs, 185 μs). Based on these 54 decay events, the lifetime of 94mRu44+ in the rest frame was calculated to be 194(121) μs. The new lifetime result is within the error range of the previous result 218(148) μs, with higher precision.
Subjects: Physics >> Nuclear Physics submitted time 2023-12-06
LI Yun-qiu
LI Cong-bo
ZHENG Yun
LI Tian-xiao
WU Xiao-guang
HONG Rui
WU Hong-yi
ZHENG Min
ZHAO Zi-hao
HE Zi-yang
LI Jin-ze
LI Guang-shun
GUO Cheng-yu
NI Lei
ZHOU Zhen-xiang
HE Chuang-ye
LIU Fu-long
ZHOU Xiao-hong
LIU Min-liang
ZHANG Yu-hu
Abstract： High spin states of 94Nb have been studied with the 82Se(18O, p5n)94Nb fusion evaporation reaction at anincident beam energy of 82and 88 MeV. The level scheme of 94Nbhas been modified and extended with 15 newγrays. Based on γ-γcoincidence relationships，DCO ratios and linear polarization measurements, the new level structures in 94Nb have been interpreted in terms of the shell model calculations performed in the configuration space π(1f5/2, 2p3/2, 2p1/2, 1g9/2 ) for the protons and ν(2p1/2, 1g9/2, 1g7/2, 2d5/2 ) for the neutrons.
Peer Review Status:
Awaiting Review
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2020-11-19 Cooperative journals: 《干旱区地理》
Abstract：提高干旱预测精度能为流域干旱应对及风险防范提供可靠数据支撑，构建比选合适的干 旱模型是当前研究的热点。研究以4个时间尺度（3、6、9、12月）标准化降水指数（SPI）为表征指标，利用小波神经网络（WNN）、支持向量回归（SVR）、随机森林（RF）三种机器学习算法分别构建了海河北系干旱预测模型，利用Kendall、K-S、MAE 三种检验方法判定模型表现及其稳定性。研究表明：（1）WNN、SVR模型呈现结果在不同时间尺度SPI 存在差异，WNN最适合12个月尺度SPI 干旱预测；SVR最适合6个月尺度SPI 干旱预测。（2）对3、12个月尺度SPI，RF预测性能最优（Kendall＞0.898，MAE＜0.05）；对6、9个月尺度SPI，SVR预测性能最优（Kendall＞0.95，MAE＜0.04）。（3）模型预测性能稳定性存在区别，RF预测稳定性最高，其次为SVR。（4）构建的三种模型表现异同主要是因为SVR转为凸优化问题解决了WNN易陷入局部最优解的不足，从而提高了模型预测性能，RF集成多样化回归树，降低了弱学习器的负面影响，提高了模型预测准确率及稳定性，同时，RF处理包含噪声的降水数据的能力更强。
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2019-08-02 Cooperative journals: 《干旱区地理》
Abstract：全生育期内作物需水量的研究是农业水资源有效利用和进行合理灌溉的重要依据。基于三江平原22个气象站点2000—2015年逐日气象观测资料及中国区域地面气象要素数据集，利用国际粮农组织 （FAO）Penman-Monteith模型和分段单值平均作物系数法，分别对三江平原水稻、玉米和大豆的作物需水量进行计算，分析作物需水量年际变化特征，采用通径分析法研究作物需水量的变化成因。结果表明：（1）三江平原16 a来年均参考作物蒸散量为537.4 mm，日均为 3.5 mm，呈波动减少趋势。（2）生长季内，水稻在分蘖期需水量最大，为177.1 mm，玉米在七叶期需水量最大，为99.7 mm，大豆在结荚期需水量最大，为96.1 mm；水稻、玉米和大豆的净灌溉需水量分别为195.4 mm、130.8 mm和72.2 mm，对灌溉的依赖程度水稻>玉米>大豆。（3）由通径分析结果可知，三江平原作物需水量的主要影响因素为净辐射、气温和日照时数。
Subjects: Geosciences >> Atmospheric Sciences submitted time 2018-10-23 Cooperative journals: 《干旱区地理》
Abstract： 开展干旱预测是有效应对干旱风险的前提基础，本文根据1960~2016年三江平原7个站点逐日降水和气温数据，利用ARIMA和ANN模型对不同时间尺度标准化降水蒸散指数(SPEI)序列进行分析建模预测。借助相关系数R、纳什效率系数NSE、Kendall秩相关系数 、均方误差MSE和Kolmogorov–Smirnov (K-S) 检验对模型的有效性进行了判定，然后分别用ARIMA和ANN模型进行12步预测，并将预测值与实际值进行比较。结果表明：(1) ARIMA模型和ANN模型对SPEI的预测能力都随时间尺度的增加而逐渐提高；(2) 两种模型对3、6个月尺度SPEI的预测精度偏低，9、12、24个月的SPEI的预测精度在70%以上；(3) SPEI-9、SPEI-12、SPEI-24三个时间尺度ANN模型的预测精度优于ARIMA模型。
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