Identifying US business cycle regimes using dynamic factors and neural network models

We use dynamic factors and neural network models to identify current and past states (instead of future) of the US business cycle. In the first step, we reduce noise in data by using a moving average filter. Dynamic factors are then extracted from a large-scale data set consisted of more than 100 variables. In the last step, these dynamic factors are fed into the neural network model for predicting business cycle regimes. We show that our proposed method follows US business cycle regimes quite accurately in-sample and out-of-sample without taking account of the historical data availability. Our results also indicate that noise reduction is an important step for business cycle prediction. Furthermore, using pseudo real time and vintage data, we show that our neural network model identifies turning points quite accurately and very quickly in real time.     

基于频率的Read Mapping种子选择算法

选择具有最低频率的最优种子是一个复杂的计算问题,往往需要很长时间.提出了一种read的基于频率的合并种子选择算法(FMSS),该算法能够高效地选择接近最优的种子集合,可用于改善现有映射工具的性能.实验对比了平均种子选择方法和当前最优的种子选择策略(OSS,optimal seed solver),结果显示FMSS算法能够用很少的时间代价给出接近OSS的最优种子集合,这表明FMSS算法可集成到现有映射工具中用于处理更大规模的read mapping问题.     

Optical sensing of explosives in wastewater by competitive complexation

A facile strategy for optical sensing of explosives with the assistance of 1,3,5-Triazine-2,4,6-triamine(MEL) in aqueous solution is proposed. Upon exposure to MEL, the electron-sufficient amino group in MEL was prone to form complexes with electron-deficient nitro group in explosives. The interaction could be tuned by the amount of MEL to fully consumed nitro-contained explosives dissolved in wastewater, thus prevented the gold nanoparticles(GNPs) from combining with MEL. In comparison with common detection method, the dose-response curve procedure reported here was in good linear relationship from 0 μM to 80 μM with good correlation factor(R~2= 0.9871), and was satisfactorily agreed with the proposed theoretical model. The detection limit(Lo D) was1.1 μM by spectrometer, 3.0 μM visualized by naked eyes and 21.3 nM by calculation. The procedure described in this study could be finished within a few minutes and showed its effectiveness in explosive detection upright on the gold surface in real wastewater, making this proposed method a powerful tool in several sensing platforms.     

非自治随机Kuramoto-Sivashinsky方程的Wong-Zakai逼近

在Wong-Zakai逼近下证明了非自治Kuramoto-Sivashinsky方程吸引子的存在性.     

中国与“一带一路”沿线部分国家的经济关系动态分析

GTAP(Global Trade Analysis Project)模型综合考虑了资本总量、资本流动、人口因素、国民生产总值等多项指标,可以用于各相关国的经济发展和经济合作互动关系分析.选用GTAP模型,分析了中国与一带一路沿线部分国家的经济互动关系.在西亚地区选择了沙特阿拉伯、以色列、伊朗、阿曼、阿联酋、科威特、伊拉克共7国,分别在降低关税20%和降低关税50%两种假设条件下展开实证分析.实证结果显示:在关税分别降低20%和50%两种假设条件下,中国和西亚诸国的GDP都有一定程度增加,各国之间进出口规模都有一定程度的扩大,这表明"一带一路"倡议对于沿线各国的经济发展和合作互动具有明显的促进作用.     

道德风险约束下的最优融资结构——动态金融契约研究综述

债务违约、企业资金链断裂与破产,以及宏观层面的金融危机等经济金融现象促使经济学家反思金融契约的资源配置效率与风险问题.以契约理论的建模技术为逻辑主线,以信息非对称环境中最优契约设计与融资结构优化为关注对象,结合融资结构、资产定价与道德风险之间的内在联系,对动态金融契约理论的研究方法与研究成果进行了系统评述,并根据金融契约理论发展逻辑导出公司金融与资产定价的理论融合方向.基于理论发展路径,初步探讨了动态金融契约理论的未来拓展方向,并结合当前我国经济结构特点给出了该理论的应用前景.     

基于非线性和测试覆盖率的软件可靠性增长模型

软件可靠性增长模型一般假设故障是独立的,且检测到的故障能够被排除。但在工程中,一些检测到的故障可能无法排除,在排除过程中也可能会引入新的故障。考虑上述因素,本文假设故障的引入过程与时间呈现非线性关系,通过测试覆盖率函数来表示软件故障检测率,建立了基于非齐次泊松过程(non-homogeneous Poisson process, NHPP)的软件可靠性增长模型。为规避参数估计过程中模型函数导数连续性和存在性的限制,应用一个自适应变化的实值遗传算法进行计算。最后通过一个真实软件失效数据集对模型参数进行计算,利用不同的评价准则将所提模型和现有模型进行比较,说明所提模型的优越性和准确性。     

条件故障下3-元n-立方体的容错分析

研究了条件边故障下3-元n-立方体中较大连通分支点的数目，进而证明了3-元n-立方体是(4n－6)-条件边故障强Menger边连通的。最后通过一个反例说明该结果是最优的。     

Effects of Cr and Mo elements on the microstructures and compressive properties of the in situ (TiC_xN_y–TiB_2)/Ni cermets

In-situ(TiC_xN_y–TiB_2)/Ni cermets with 70 wt%TiC_xN_y–TiB_2 were successfully fabricated by combustion synthesis and hot pressing sintering in Ni-Ti-B_4C-BN powder systems.The microstructures,density,compressive properties,and hardness of the TiC_xN_y–TiB_2/Ni cermets with the addition of 0–8 wt%Cr/Mo to the Ni-Ti-B_4C-BN powder systems were compared and analysed.The results showed that the ceramic particles distributed uniformly in the cermets,and the size of the ceramic particles reduced with the Cr/Mo addition.Both Cr and Mo addition can improve the hardness,compressive properties,and fracture strains of the cermets.The hardness,compressive strength,and fracture strain of the(TiC_xN_y–TiB_2)/(Ni+Cr)cermets increased from 1561 HV,2.94 GPa,and 2.9%to 1864 HV,3.65 GPa,and 3.4%,respectively when the Cr content increased to 5 wt%.The hardness and compressive strength of the(TiC_xN_y–TiB_2)/(Ni+Mo)cermets increased from 1561 HV and 2.94 GPa to 1902 HV and 3.43 GPa,respectively when the Mo content increased to 8 wt%.The cermets with Cr had better compressive properties than the cermets with Mo.