考虑渗透率和流体黏度的致密油藏探测半径

探测半径是评价油藏控制程度和井控储量的重要参数。为了解决低渗透致密油藏探测半径计算方面存在的问题,建立了考虑渗透率和黏度的模型,推出了新的导压系数,得到了考虑流体和地层因素的微分方程。在此基础上,应用稳态依次替换法和质量守恒法推导出相应的探测半径方程,并用数值方法求解。研究结果表明:低渗透致密油藏地层中新的导压系数比经典理论中的导压系数小;探测半径与井的产量有关,同时也与渗透率和黏度的变形系数有关,渗透率的变形效应会减小探测半径,黏度的变形效应会增大探测半径。     

微量银对Sn0.7Cu钎料物理性能及钎焊工艺性能的影响

SnCu共晶钎料是公认的SnPb钎料最具潜力的替代品,尤其在波峰焊上,但与其它无铅钎料相比,该钎料物理性能及铺展性能差,影响其广泛应用.通过在Sr0.7Cu合金基础上添加微量银来改善合金性能.结果表明,银含量对Sn0.7CuxAg钎料熔点影响不大,最大变化仅为0.3℃;随银含量增加,电阻率逐渐升高;同时,在Sn0.7C...     

Impact of Distribution Type in Bayes Probability Flood Forecasting

Bayesian forecasting system (BFS) is widely applied to the hydrological forecast. Hydrological forecast processor (HUP), a key part of the Bayesian probability prediction, is conducted at the assumption that the rainfall is certain, which can simultaneously quantify the uncertainty of hydrological model and parameter. In the HUP, the runoff is usually assumed to obey Logweibull distribution or Normal distribution. However, Distribution type of the runoff is not certain at different areas, and there are few distribution types of HUP in existence. So common distribution types are needed to develop the HUP to provide an effective forecast result. In this paper, Nonparametric kernel density estimation, Pearson III and Empirical distribution were introduced as the prior distribution of HUP to eliminate the parameter uncertainty of probability density function. Also, the five distributions were compared in this study to get the diversity of distribution types and search the best appropriate distribution type. The 52 floods during 2004a-2014a of ZheXi basin are employed to calibrate and validate the different distribution types of BFS. The results show that the LogWeibull and Empirical Bayesian probabilistic model has the best performance on average results compared with the other four distribution models. Meanwhile the other distribution types proposed in this study have the similar ability on interval width and the containing rate of probability forecasting results. This demonstrates that more new distributions are required to make BFS more robust.     

松香含量对Zn20Sn钎料用松香基助焊剂的影响

锌基钎料润湿性差已经成为锌基钎料推广应用的瓶颈.通过在传统松香中加入适量有机酸活性剂、溶剂、缓蚀剂及表面活性剂等化合物组成Zn20Sn钎料用新型松香基助焊剂,来改善Zn20Sn钎料在铜基板上的润湿性能.结果表明,松香含量在40％～60％范围内时,助焊剂在物理稳定性、不粘性、腐蚀性等方面均符合国家标准要求;Zn20Sn钎料在铜基板上的铺展面积和铺展率随着松香含量的增加呈先增后减的趋势.当松香含量为55％时,Zn20Sn钎料在铜基板上的铺展性最好,铺展面积和铺展率达到最大,分别为70.3 mm2和87％,焊点饱满光亮,焊缝无明显缺陷,显示其对Zn20Sn钎料具有良好的助焊效果.     

A Hydrologic Uncertainty Processor Using Linear Derivation in the Normal Quantile Transform Space

Water Resources Management - Hydrological forecasting plays an important role in basin flood control systems, and the uncertainty of hydrological forecasting is helpful to reveal basin hydrological...     

风光水互补系统时间序列变量概率预报框架

风光水互补系统实时调度受风速、太阳辐射强度、径流和电力负荷等时间序列变量的不确定性影响,如何准确预报这些变量并量化预报的不确定性是风光水互补系统面临的关键难题。为此,本研究提出一种基于深度学习模型的时间序列变量概率预报框架。首先,从时间序列数据中挖掘特征输入并采用相关系数对生成的特征进行初选;其次,基于深度学习模型和高斯过程回归构建时间序列变量概率预报模型,同时分别通过0-1规划思想和贝叶斯优化算法实现特征组合优化和超参数优选;进而,从确定性预报、概率预报和可靠性3个方面对预报模型进行全面评价;最后,以雅砻江流域风光水互补先期试点示范基地作为研究对象,分别在径流、风速、光伏和负荷4个数据集上与目前7个不同的时间序列变量预报模型进行全面对比,验证本研究提出预报框架的精度和概率综合性能。     

Hydrological Uncertainty Processor (HUP) with Estimation of the Marginal Distribution by a Gaussian Mixture Model

Water Resources Management - Uncertainty assessments of hydrological prediction results can reflect additional hydrological information and reveal important hydrological characteristics of river...     

Single Ho3+‐Doped Upconversion Nanoparticles for High‐Performance T2‐Weighted Brain Tumor Diagnosis and MR/UCL/CT Multimodal Imaging

Multimodal bio‐imaging has attracted great attention for early and accurate diagnosis of tumors, which, however, suffers from the intractable issues such as complicated multi‐step syntheses for composite nanostructures and interferences among different modalities like fluorescence quenching by MRI contrast agents (e.g., magnetic iron oxide NPs). Herein, the first example of T₂‐weighted MR imaging of Ho³⁺‐doped upconversion nanoparticles (UCNPs) is presented, which, very attractively, could also be simultaneously used for upconversion luminesence (UCL) and CT imaging, thus enabling high performance multi‐modal MRI/UCL/CT imagings in single UCNPs. The new finding of T₂‐MRI contrast enhancement by integrated sensitizer (Yb³⁺) and activator (Ho³⁺) in UCNPs favors accurate MR diagnosis of brain tumor and provides a new strategy for acquiring T₂‐MRI/optical imaging without fluorescence quenching. Unlike other multi‐phased composite nanostructures for multimodality imaging, this Ho³⁺‐doped UCNPs are featured with simplicity of synthesis and highly efficient multimodal MRI/UCL/CT imaging without fluorescence quenching, thus simplify nanostructure and probe preparation and enable win–win multimodality imaging.     

锡含量对Bi5Sb钎料铺展性能及抗拉性能影响

在Bi5Sb基体钎料中添加1%～8%Sn,研究锡对Bi5Sb基无铅钎料润湿性能及力学性能的影响.结果表明,在Bi5Sb钎料中添加适量的锡,可使Bi5SbxSn钎料熔点控制在270～280℃左右,与Bi5Sb钎料相比,变化不大,但钎料合金铺展性能和抗拉强度明显提高.当锡含量为8%时,Bi5Sb8Sn钎料合金钎焊铺展性能和...