基于模态符号数据分析的混合推荐算法

传统混合推荐算法基于点数据来描述用户模型,存在信息丢失、难以统筹考虑用户所有偏好信息等问题,严重影响了推荐系统的质量和效率。针对该问题,以符号数据为基础,建立了基于模态符号数据分析的混合推荐算法。用模态符号数据对用户建模,引入模态符号数据的距离度量计算用户兴趣模型间的相似性,同时整合用户人口统计信息的相似性,形成用户的综合相似性,最终完成推荐。实验结果表明论文方法在应对数据稀疏性及新用户问题时,具有更高的推荐精度。     

Consistency analysis of accelerated degradation mechanism based on gray theory

A fundamental premise of an accelerated testing is that the failure mechanism under elevated and normal stress levels should remain the same. Thus, verification of the consistency of failure mechanisms is essential during an accelerated testing. A new consistency analysis method based on the gray theory is pro- posed for complex products. First of all, existing consistency ana- lysis methods are reviewed with a focus on the comparison of the differences among them. Then, the proposed consistency ana- lysis method is introduced. Two effective gray prediction models, gray dynamic model and new information and equal dimensional （NIED） model, are adapted in the proposed method. The process to determine the dimension of NIED model is also discussed, and a decision rule is expanded. Based on that, the procedure of ap- plying the new consistent analysis method is developed. Finally, a case study of the consistency analysis of a reliability enhancement testing is conducted to demonstrate and validate the proposed method.     

评价决策单元相对效率的修正DEA方法

在原有理论[1] 的基础上提出了一个新的DEA模型———CCRH ,给出了强有效的概念 ,论证了相关理论。CCRH模型与CCR模型相比有以下几个优点 :①描述决策单元的相对效率更确切 ;②利用参考决策单元的生产前沿面来描述评价决策单元“生产”情况得到的结果更加符合实际 ;③可以考查评价决策单元输入、输出变化时对其效率的影响。     

Angular glint calculation and analysis of radar targets via adaptive cross approximation algorithm

Angular glint is a significant electromagnetic （EM） scattering signature of extended radar targets. Based on the adaptive cross approximation （ACA） algorithm accelerated method of moments （MoM） and the plane incident wave assumption, the narrowband, wideband and newly developed high-resolution range profile （HRRP） based angular glint calculation formulations are derived and applied to arbitrarily shaped three-dimensional （3D） perfectly electrical y conducting （PEC） objects. In addition, the near-field angular glint is emphasized, which is of great importance for radarseeker applications. Furthermore, with the HRRP based angular glint, an approach to rigorously determine range resolution cel s which own relatively smal er angular glint is provided. Numerical results are presented with new findings to demonstrate the usefulness of the developed formulations.     

Higher-order principal component pursuit via tensor approximation and convex optimization

Recovering the low-rank structure of data matrix from sparse errors arises in the principal component pursuit （PCP）. This paper exploits the higher-order generalization of matrix recovery, named higher-order principal component pursuit （HOPCP）, since it is critical in multi-way data analysis. Unlike the convexification （nuclear norm） for matrix rank function, the tensorial nuclear norm is stil an open problem. While existing preliminary works on the tensor completion field provide a viable way to indicate the low complexity estimate of tensor, therefore, the paper focuses on the low multi-linear rank tensor and adopt its convex relaxation to formulate the convex optimization model of HOPCP. The paper further propose two algorithms for HOPCP based on alternative minimization scheme： the augmented Lagrangian alternating direction method （ALADM） and its truncated higher-order singular value decomposition （ALADM-THOSVD） version. The former can obtain a high accuracy solution while the latter is more efficient to handle the computationally intractable problems. Experimental results on both synthetic data and real magnetic resonance imaging data show the applicability of our algorithms in high-dimensional tensor data processing.     

基于优化MRVA的Φ-OTDR相干衰落抑制方法

本文针对相位敏感光时域反射(Φ-OTDR)系统的一种相干衰落抑制方法旋转矢量移动平均(MRVA)进行了优化,获得了性能更优的相干衰落抑制.该优化方法从两个方面展开,首先使用加权窗口代替MRVA方法中的矩形窗口,兼顾测量精度和空间分辨率;然后根据移动平均与低通滤波的数理等效性,将时域移动平均转换为运算速度更快的频域低通滤波,提高信号处理效率.实验结果表明,相较于MRVA方法,该方法的解调相位精度提高了约23%,计算时间从0.957 s缩短至0.026 s,运算速度提高约36倍.     

无失效数据下弹上机电产品加速贮存寿命评估方法

针对现有加速贮存寿命评估方法难以有效应对无失效数据、两参数Weibull模型拟合高可靠、长寿命机电产品寿命分布精度不高的问题,提出了基于E-Bayes理论和三参数Weibull寿命分布模型的弹上机电产品加速贮存寿命评估方法。对两参数Weibull在拟合高可靠、长寿命机电产品寿命分布时存在的的精度不足问题进行了论述,给出了三参数Weibull下的弹上机电产品寿命分布模型。在阿伦尼乌斯模型、Nelson累积失效假定等基础上,建立了单次步进应力加速贮存寿命试验数据向多次常温应力定时截尾试验数据的等效折算方法,并引入E-Bayes理论实现了对定时截尾试验无失效数据下失效概率的有效求解。针对复杂等效折算公式中的Weibull参数估计问题,设计了粒子群优化算法实现对参数的高精度求解,并给出了基于蒙特卡罗法的贮存寿命置信下限评估方法,从而实现对弹上机电产品的高效贮存寿命评估。以某型弹上惯性测量单元为应用对象,验证了所提方法的有效性和合理性。     

障碍物对火焰加速及爆燃转爆轰过程影响研究

为研究设障管内火焰传播特性以及爆轰转捩机理,比较固体障碍物和流体障碍物对火焰加速以及爆燃转爆轰（DDT）过程影响的区别,采用CFD软件对丙烷、氧气和氮气在爆轰管内爆燃转爆轰过程开展了模拟研究。研究结果表明：火焰前锋在固体障碍物的作用下,呈现先加速后减速的趋势;而火焰前锋在流体障碍物的作用下,加速趋势更为稳定。将首个固体障碍物改为流体障碍物能够缩短爆燃转爆轰的时间与距离,爆燃转爆轰距离与时间随着流体障碍物个数的增加呈现先减小后增加的趋势。     

奥曲肽微球-凝胶复合体系的制备及加速释放

本研究旨在解决奥曲肽微球前期释放过程中的突释,将其设计成可注射的微球-凝胶复合体系。采用乳化溶剂挥发法制备奥曲肽微球,使用Box-Behnken响应面法对凝胶基质处方参数进行优化。通过考察pH、乙腈和乙醇浓度对该复合体系释药的影响,确定体外加速释放的条件,建立凝胶微球的体外加速释放方法。确定最优处方为：PL188、PL407和HPMC的质量分数分别为3%、22.2%和1%,成胶温度为37℃。该复合体系可有效减少微球前期突释,使药物释放行为更加稳定。确定体外加速释放条件为：含3%乙腈、6%乙醇、pH为7.4的PBS缓冲液为释放介质。该体外加速释放方法可快速有效评价复合体系的释放行为。     

机群系统中矩阵的并行QR分解算法

随着高速网络技术的快速发展,机群系统已经成为并行计算的主要平台,由于它的高通信延迟,某些在并行机上实现的细粒度并行算法已不适合在该环境下运行,为此有必要研究它们在机群系统中的并行实现.基于这一点,对矩阵的QR分解提出了一种新的任务划分策略,并由此得到了它的一种粗粒度并行算法.实验结果表明,设计的并行算法在机群系统中具有较高的加速比.