基于Lasso+SVM的制造业上市公司财务风险组合预警模型

根据组合预测思想构建了基于Lasso+SVM的制造业上市公司财务风险组合预警模型,包括串联型组合和信息融合型组合两种,并选取22个财务指标建立了财务预警指标体系,对我国86家制造业上市公司的财务状况进行了预测,还与单一风险预警模型预测效果进行了比较,结果发现:财务风险组合预警模型的预测效果明显高于单一预警模型,用第t-...     

转动诱发原子核量子相变的一种可能途径

基于微观IBM理论,提出转动诱导出玻色子量子相变的一种可能途径:一旦原子核在受到高能激发或作快速旋转时,假如外界提供的能量足以使玻色子完成拆对顺排,则核处于集体相与单粒子态的共存相,其特征是出现较密集的能谱;假如能量不足以完成拆对或顺排,可能发生两种情况之一,当核旋转达到某个临界转动频率ω_c时,或者一个高角动量的玻色子脱离“集体”而“游离”出来,或者发生一个高角动量的玻色子转变为一个低角动量的玻色子,核仍旧处于集体相;均会伴随出现光辐射,产生基态带的一条能级——相变信号.正是这类玻色子相变导致了原子核的量子相变.本物理图像统一了玻色子拆对顺排相变和退耦释放光子相变的描述.以¹⁰⁰Pd核的14⁺₁,14⁺₂和14⁺₃态的产生机理为例,对模型作了仔细说明.     

Practical Reference-Frame-Independent Measurement-Device-Independent Quantum Key Distribution Systems Against the Worst Relative Rotation of Reference Frames

Reference-frame-independent measurement-device-independent QKD(RFI-MDI-QKD), immune to both the slow unknown drift of reference frames and detector side channel attacks, can generate information-theoretic secure keys. Despite its natural resistance to the slow drift of reference frames, the performance of practical RFI-MDI-QKD systems descends with the increasing drift of reference frames. In this paper, we demonstrate the worst relative rotation of reference frames for practical RFI-MDI-QKD systems, and investigate their performance against the worst-case scenario,both of which are unclear to date. Simulation results show that, practical RFI-MDI-QKD systems can achieve quite good performance even against the worst-case scenario, which clearly demonstrates that it is possible to implement practical MDI-QKD systems with freely drifting reference frames.     

Silicon Dioxide Coating Deposited by PDPs on PET Films and Influence on Oxygen Transmission Rate

A silicon dioxide film is deposited on the polyethyleneterephtMate （PET） by a penning discharge plasma source at ambient temperature in a high vacuum chamber. Hexamethyldisiloxane and oxygen are adopted as precursor and reactive reagent to grow a nano-scale silicon dioxide layer on polymer surfaces. For the chemical structure analysis X-ray photoelectron spectroscopy is performed to demonstrate the content of Si, 0 and C elements. It is noticed that a higher silicon concentration is contained if Ar plasma is used for pretreatment. X-ray diffraction analysis shows that a micro-crystal silicon dioxide is formed by peak patterns at 25,84° and 21.8°. The barrier properties examined by oxygen transmission rate show that the permeation parameter of the 12-μm-thick PET film drastically decreases from 135 cc/m^2 per day for the control one to O. 713 cc/m^2 per day for the as-deposited one after Ar plasma treatment. The surface morphology related to the barrier properties of SiOx-coated polymers os also investigated by scanning electron microscopy and atomic force microscopy.     

Pulse Temporal Cleaner Based on Nonlinear Ellipse Rotation by Using BK7 Glass Plate

We report a new pulse cleaning technique to enhance the contrast ratio of intense ultra-short laser pulses. A pulse temporal cleaner based on nonlinear ellipse rotation by using BK7 glass plate is developed, and a contrast ratio improvement of two orders of magnitude for the milli-joule level femtoseeond input pulses is demonstrated, the total transmission effieiency of the pulse cleaner is 16. 7%.     

多元化学生评价实施的影响因素探析

立足于课堂且以促进学生的全面发展为目的的多元化学生评价的实践研究(尤其是在高中)在我国还比较欠缺。究竟是哪些因素影响了多元化学生评价的实施?在操作的过程中又该怎样考虑这些因素?本文作者以建构主义和多元智能理论为指导,在化学教学中进行了一学期尝试性的研究,探析了影响多元化学生评价实施的诸多因素:教师、学生、教学内容及手段、高考、作品展示、评价主体多元化执行的程度等;并提出了相关建议。     

零电流示波电位滴定盐酸异丙嗪

盐酸异丙嗪是一种较重要的抗组胺药,现行的分析标准为非水滴定法^[1],此外尚有分光光度法^[2]、伏安法^[3]、电极法^[4]、液相色谱法^[5]和流动注射分析法^[6]等。本文将高鸿提出的零电流示波电位滴定法^[7]中的铂片电极修饰一层含四苯基硼酸-异丙嗪电活性物质的PVC膜,使电极对异丙嗪产生响应,可用于四苯基硼酸钠直接滴定异丙嗪的终点指示。     

Tunable phase-stabilized infrared parametric laser source

This paper reports that the tunable self-phase-stabilized infrared laser pulses have been generated from a two-stage optical parametric amplifier. With an 800 nm pump source, the output idler pulses are tunable from 1.3 μm to 2.3 μm, and the maximum output energy of the idler pulses is higher than 1 mJ at 1.6 μm by using 6 mJ pump laser. A carrier-envelope phase fluctuation of ～ 0.15 rad (rms) for the idler pulses is measured for longer than one hour by using a home build f-to-2f interferometer.     

[Cp2Ln(m-h1:h2-OC(SR)=CPh2 )]2 的合成和表征

[Cp2Ln（μ-SR）]2 was reacted with Ph2C=C=O to yield ketene mono-insertion products [Cp2Ln（μ-η1：η2-OC（SR）=CPh2）]2 [R=Bn, Ln=Yb （1）, Er （2）, Y （3） and R--Ph, Ln=Yb （4）], indicating that the reactions of organolanthanide thiolates with ketenes are independent of the nature of the thiolate ligand and the ketene as well as the reaction condition. These reactions could provide an efficient method for the synthesis of organolanthanide complexes with the a-thiolate-substituted enolate ligand. All these complexes were characterized by elemental analysis and spectroscopic properties and the structure of complex 1 was determined through X-ray single crystal diffraction analysis.     

用层次分析法对学生进行综合评价

学生的综合评价工作是学校的重要工作内容.如何从思想、学习、生活等各个方面对其进行综合考察,并使之科学化、合理化,是各个院校学生工作一直探索的问题.采用能给定量描述的决策问题带来极大方便的层次分析法(Analytic Hierarchy Process),把学生评价体系归结为5个准则27个指标,通过计算各级判断矩阵,得到了各个指标的权重,并把最终的计算结果应用到学生评优评三好等多项实际工作中.