自适应分组成对比较法:原理及种子的选择

声品质主观评价实验中,大样本量的成对比较实验由于评价时间随样本数量的平方增长而变得难以实现,为此本文提出了自适应分组成对比较法.该方法不仅可以有效减少评价工作量并使得实验易于实现,而且通过对种子样本的调整,避免了普通的分组成对比较法由于关联样本选取不当而减小实验结果准确度的情况.论文给出了自适应分组成对比较法的数学原理和实现方法,提出了选取最佳种子的经验公式,最终通过计算机仿真和主观评价实验,与传统成对比较法的结果进行比较,证明了自适应分组成对比较法的有效性.     

学生参与化学实验室安全管理的探索与实践

化学实验室安全管理是高校安全管理工作的重点,随着实验室规模扩大,与实验室安全相关的管理制度、管理队伍、管理模式等诸多问题逐渐暴露出来。学生作为实验课程的实施主体,在实验室安全管理中一直缺乏足够的参与感和发言权。客观分析了学生在安全管理中的几点优势,通过分析学生参与实验室安全管理的可行性,提出对学生开展全方位的安全教育,提升学生安全素养;启用智能化管理平台,实现化学药品、“三废”、气瓶、大型仪器的科学化管理;精细布防学生工作,实行精准化管理模式等措施。通过在学生中积极开展安全文化建设并制定积极的激励政策,促进学生参与实验室安全管理模式的健康发展。     

换个角度看世界之……寻饱篇

这一生惟一一次吃到手脚发麻兼舌头痛的经历,发生在去年归国。当然“这一生”到目前为止并不很久,加上没有什么举足轻重的社会地位,少了许多必须以佳肴相酬的挚友。就是这样,热情的家人亲戚还是让我体会到了饱的痛苦。这话说出来连自己也吃了一惊,连忙补了句“罪过”才安下心来。自从少年离家,一生中的一半是处于一种长久饥饿的状态下,当然不是指腹间的饥饿,更像味蕾的饥饿,对“正宗”二字的相思难耐。十几年中,我和老公为了一家新开的中餐馆可以长途跋涉,不辞辛苦;对于每一个有关美味的流言进行认真收集、实地考察。就是这样,我们仍旧不得…     

10-W cladding-pumped fiber laser with single transverse mode output

A Yb-doped double-clad fiber laser is demonstrated with a measured power output of 10.6 W and a fundamental spatial mode. The optical-to-optical conversion efficiency is 44% and the slope efficiency is 86% closed to quantum efficiency of optical conversion. In our laser system, a D-shape (340 μm/400 μm) inner cladding Yb-doped fiber is used as the gain material within the Fabry-Perot cavity. Multimode diode pump radiation is injected into the cladding through an end facet of the composite fiber.     

立方氮化硼的振动光谱及反射光谱的研究

 将黑色、黄色、棕色三种小于50 μm立方氮化硼粉末为样品，研究了其红外光谱、拉曼光谱、反射光谱，结果表明：（1）样品的红外光谱中，1 818 cm^-1和1 548 cm^-1属于cBN的晶格本征振动，而立方氮化硼的晶格本征振动外的晶体缺陷吸收则发生在~800 cm^-1，1 580 cm^-1~1 740 cm^-1和大于2 400 cm^-1处。（2）拉曼光谱测试表明，在1 052 cm^-1和1 304 cm^-1附近出现的散射与cBN不具有反演中心及cBN具有立方结构这样的事实相一致，并且这种散射伴随着布里渊区中心声子的横向和纵向发射。144 cm^-1附近出现的散射，被认为是由于局部振荡模式的出现，在反斯托克斯区造成的信号，这与晶格中杂质缺陷有关。（3）依据得到的反射光谱，计算了cBN单晶禁带宽度，发现这三种cBN都具有大于金刚石的禁带宽度值，分别为：E_g(黑)=6.21 eV，E_g(黄)=5.73 eV，E_g(棕)=5.71 eV。     

中西医结合治疗妊娠恶阻20例临床观察

1 临床资料 妊娠恶阻20例中,年龄最大者35岁,最小者20岁;脾胃虚弱型8例,肝胃不和型12例;尿酮体阳性者16例.     

Optical properties of ytterbium-doped tandem-pumped fiber oscillatorOptical properties of ytterbium-doped tandem-pumped fiber oscillatorOptical properties of ytterbium-doped tandem-pumped fiber oscillator

With the rapid development of ytterbium-doped fiber lasers, some obtrusive limitations on power scaling appeared. In order to avoid these problems, a scheme called tandem pumping is introduced into the fiber laser field. In this paper, the optical properties of an ytterbium-doped tandem-pumped fiber oscillator are presented. According to the oscillator profile, the proper gain fiber type and pump wavelength range are picked out, under the comprehensive consideration of laser conversion efficiency and beam quality. In addition, the photodarkening performances of tandem pumping lasers and conventional ones are compared based on practical application, with all possible impact parameters taken into account. Moreover, an all-fibered tandem-pumped oscillator centered at 1079.5 nm is built, in the way of clad pumping by a 1030-rim fiber laser. The laser power of the oscillator reaches 7 W, with an opto-optic efficiency of 82.4%.     

癌基因密码子间的距离和Y-内积表示及其应用

为了深入研究正常基因变为癌基因时,氨基酸亲疏水性的变化趋势,在已经建立的代数结构的基础上给出了全新的距离及Y-内积的定义,通过计算得出GF(7)上36个本原多项式及其根,并得出了对应的生物意义的表示,利用所建立的理论数学模型分析了在胃癌,食道癌,肺癌以及B细胞淋巴癌中的p53错义突变过程中氨基酸亲疏水性的变化.结果表明...     

Noncolinear Second-Harmonic Generation Pairs and Their Scatterings in Nd~(3+):SBN Crystals with Needle-Like Ferroelectric Domains

Second-harmonic generation in Nd~(3+):SBN crystal with needle-like ferroelectric with aperiodic domain structures is investigated. Two pairs of second harmonic(SH) waves appearing in lines are observed in unpoled Nd~(3+):SBN crystals with aperiodic needle-like domains. A pair of SH waves emit from the exit face, whose intensities are angle-dependent. The angular dependence is corresponding to the spatial frequency spectrum of the aperiodic domain structure. Another pair of SH waves emit from both the side surfaces, which are mainly the scattered SH waves by needle-like domain walls and obey the theory of Rayleigh scattering.