基于预测极性动态变换的分支预测框架研究

针对动态分支预测错误率在时间上分布不均匀且高错误率比较集中的特点,该文提出一种可动态变换预测极性的分支预测方法。该方法对未经极性变换的原始动态分支预测错误率进行自适应监测,筛选出原始动态分支预测错误率高于阈值的预测错误高峰期,进而调整预测错误高峰期内分支预测器的预测极性,使经过极性变换的最终动态分支预测错误率在程序运行过程中始终低于设定的阈值。该文同时研究了全局监测、按组监测和局部监测3种分支预测错误率监测方式。实验结果表明,相同硬件资源下该方法比Gshare和Bi-Mode分支预测方法具有更高的分支预测精度。     

超高效液相色谱-串联质谱法测定乳饼中的氯霉素

目的建立一种超高效液相色谱-串联质谱法(ultra high performance liquid chromatography tandem mass spectrometry, UPLC-MS/MS)检测乳饼中氯霉素的分析方法。方法样品经乙酸乙酯提取,分析了分别经C18(100 mm×2.1 mm, 1.7μm)及MCS固相萃取柱净化、富集的结果;以乙腈-0.05%氨水为流动相,经C18色谱柱分离,采用多反应检测负离子模式进行定性及定量分析。结果 MSC固相萃取柱具有较好的回收率,氯霉素的方法检出限为0.004μg/kg,方法定量限为0.01μg/kg,在0.10、0.50、1.00、10.00 ng 4个加标水平下回收率分别为76.4%、101%、62.4%、61.1%。结论本方法灵敏度高、重复性好,可满足乳饼样品中痕量氯霉素残留的测定。     

离子色谱-脉冲安培法测定饮料中的聚葡萄糖的含量

通过优化标准方法AOAC 2000.11和GB 5009.245-2016的样品前处理过程,简单、高效准确地分析饮料中添加的聚葡萄糖含量。方法 样品经离心超滤净化,去除基质干扰,采用色谱柱分离,离子色谱-脉冲安培检测器测定,外标法定量。结果 聚葡萄糖在0.20 ~ 2.00 g/L的浓度范围内呈良好线性关系 (R2 > 0.999)。方法检出限和定量限分别为0.01 和0.03 g/L,三个添加水平的平均加标回收率为90.0%~98.8%,相对标准偏差为0.63%~2.36%。同时考察了市场上10种不同品类的饮料,加标回收率为93.0%-105%。结论 本方法样品前处理简单、快速、广泛适用于饮料中添加的聚葡萄糖含量测定。     

超高效液相色谱-串联质谱法测定蔬菜中4种氨基甲酸酯类农药残留量

目的 建立超高效液相色谱-串联质谱法测定蔬菜中4种氨基甲酸酯类农药残留量.方法 蔬菜样品经切碎,乙腈提取,分别用固相萃取柱及QuEChERS净化后,以乙腈-0.1％甲酸水溶液为流动相梯度洗脱,经CAPCELL PAK C18色谱柱分离,采用多反应监测正离子模式(multireaction monitoring in p...     

一种基于输运理论的多目标演化算法

提出了一种根据输运理论中的粒子输运方程、相空间能量定律和熵增法则构造的一种能够准确、高效地求解多目标优化问题的多目标演化算法(MOPEA).由于该算法使用了粒子系统从非平衡达到平衡的理论来定义求解多目标问题的Rank函数和Niche适应值函数,使得种群中的所有个体都有机会参与演化操作,以达到快速、均匀地求出多目标优化问题的Pareto最优解.数据实验显示,利用该算法求解多目标优化问题不仅能够使算法快速地收敛到全局Pareto前沿,同时由于该算法要求所有的粒子都要参与杂交和变异等演化操作,从而避免问题早熟现象的出现,并通过与传统演化算法的性能指标分析比较说明,使用该算法求解多目标优化问题具有明显的优越性.     

基于图像力场转换的耳廓图像识别

首先讨论了耳廓识别技术的可行性、可靠性及其特点,针对耳廓识别特点提出一种基于图像力场转换的耳廓识别方法(Force-field fisher classifier).该方法通过力场图像转换提取耳廓图像特征后,采用Fisher线性判别分类识别,减小了光照变化对耳廓识别的影响.在我们选取的耳廓图像库上识别率达到了98.5%.     

pH对离子液体辅助水热制备介孔二氧化钛结构的影响

以钛酸四丁酯为钛源, 离子液体1-丁基-3-甲基咪唑四氟化硼([C₄MIM]BF₄)为辅助剂, 采用水热法制备了锐钛矿相的介孔二氧化钛。用盐酸和氨水调节反应前驱体的pH, 考察了pH在1~11变化范围内对离子液体-水制备二氧化钛体系的影响。采用X射线衍射和N2吸附?脱附对样品的晶相和孔结构进行表征。结果表明: 离子液体抑制了板钛矿二氧化钛的形成, 随着pH的增大样品的晶化程度增强。pH在1~9较大范围变化时, 其孔径分布较窄, 平均孔径随pH增大由6.6 nm减小到5.0 nm, 此时离子液体能较好的将样品粒径控制在9 nm左右。这与透射电镜分析结果相一致。     

Theoretical studies on electronic structures,spectra and charge transporting properties of a series of Pt(CN)2 complexes

We report a quantum-chemical study of electronic, optical and charge transporting properties of four platinum (II) complexes, Pt(C^ΛN)₂ (C^ΛN = phenylpyridine or thiophenepyridine). The lowest-lying absorptions at 442, 440, 447 and 429 nm are all attributed to the mixed transition characters of metal-to-ligand charge transfer (MLCT) and ligand-centered (LC) π → π* transition. While, unexpectedly, the lowest-lying phosphorescent emissions at 663, 660, 675 and 742 nm are mainly from metal-to-ligand charge transfer (³MLCT) ligand-centered (LC) π → π* transition. Ionization potential (IP), electron affinities (EA) and reorganization energy (λ_{hole/electron}) were obtained to evaluate the charge transfer and balance properties between hole and electron. The calculated results reveal that the small structure changes of the charged states relative to the neutral ones, and the smaller IP and EA values indicate that they exhibit a relatively high structural stability versus the injection of one charge and have better holes than electron-injection abilities. The smaller λ values and the smaller differences (within 0.06 eV) between λ_hole and λ_electron indicate the better transfer balance between holes and electrons. Moreover, the attached methyl groups slightly improve the hole-injection ability and deduce the electron-injection ability. The strong phosphorescence emission and the favorable transporting properties compared with other reported complexes indicate their potential applications in as emitters OLEDs.     

婺源县低水头水电开发实践与思考

本文通过对婺源县水能资源开发实践与思考,揭示了低水头水电开发地位与意义,并指出了如何实现"在保护中开发"与"在开发中保护"理想的低水头水电开发经验与途径。     

A Parallel Genetic Algorithm Based on Spark for Pairwise Test Suite Generation

Pairwise testing is an effective test generation technique that requires all pairs of parameter values to be covered by at least one test case. It has been proven that generating minimum test suite is an NP-complete problem. Genetic algorithms have been used for pairwise test suite generation by researchers. However, it is always a time-consuming process, which leads to significant limitations and obstacles for practical use of genetic algorithms towards large-scale test problems. Parallelism will be an effective way to not only enhance the computation performance but also improve the quality of the solutions. In this paper, we use Spark, a fast and general parallel computing platform, to parallelize the genetic algorithm to tackle the problem. We propose a two-phase parallelization algorithm including fitness evaluation parallelization and genetic operation parallelization. Experimental results show that our algorithm outperforms the sequential genetic algorithm and competes with other approaches in both test suite size and computational performance. As a result, our algorithm is a promising improvement of the genetic algorithm for pairwise test suite generation.