分段滤波用于消除脉搏血氧检测中多种运动干扰的研究

脉搏血氧饱和度检测仪可以无损、实时地检测动脉血液中的含氧百分比,从而快速对人体的呼吸状况以及心肺功能作出判断,但其检测精度极易受到测试部位运动的影响.人体测试部位的运动大致可以分为突发性运动干扰以及周期性的运动干扰.突发性干扰表现在局部脉搏波的波形突变上,而周期性的干扰体现在多个局部脉搏波的波形的周期性变化上.文章有针对性地提出了一种将微分阈值分段与迭带中值滤波相结合的方法来剔除突发扰动的方法,并且在上诉方法上再加上一级多点移动平滑以消除周期性运动干扰.实验证明该方法在消除多种运动伪差上有着较好的效果,且该方法计算简单,易于实现,有着一定的实际应用价值.     

Synthesis of SnO_2 nanorods from aqueous solution:The effect of preparation conditions on the formed patterns

<正>SnO_2 nanorods were deposited on the Si substrates in an aqueous solution containing both SnCl_4 and CO(NH_2)_2.It is found that different self-assembled patterns of SnO_2 nanorods can be obtained by changing the deposition conditions such as the molar ratio of CO(NH_2)_2 to SnCl_4 and the pretreatment of the substrate.Scattered SnO_2 nanorods,for example,can be changed into flower-like patterns when the molar ratio of CO(NH_2)_2 to SnCl_4 is raised,and well-aligned nanorod arrays can be formed when the pretreatment of the substrate is changed.In addition,some interesting patterns,e.g.tree-like patterns,can also be observed.     

Fracture dynamics problem on mode I semi-infinite crack

By means of the theory of complex functions, fracture dynamics problems concerning mode I semi-infinite crack were studied. Analytical solutions of stress, displacement and dynamic stress intensity factor under the action of moving increasing loads Pt ³/x ³, Px ³/t ², respectively, are very easily obtained using the ways of self-similar functions. The correlative closed solutions are attained based on the Riemann–Hilbert problems.     

Non-contact evaluation of the resonant frequency of a microstructure using ultrasonic wave

This paper presents a novel non-contact method for evaluating the resonant frequency of a microstructure, Firstly, the microstructure under test is excited by ultrasonic waves. This excitation method does not impose any undefined load on the specimen like the electrostatic excitation and also this is the first actual use of ultrasonic wave for exciting a microstructure in the literature. Secondly, the amplitudes of the microstructure are determined by image edge detection using a Mexican hat wavelet transform on the vibrating images of the microstructure. The vibrating images are captured by a CCD camera when the microstructure is vibrated by ultrasonic waves at a series of discrete high frequencies （〉30 kHz）. Upon processing the vibrating images, the amplitudes at various excitation frequencies are obtained and an amplitude-frequency spectrum is obtained from which the resonant frequency is subsequently evaluated. A micro silicon structure consisting of a perforated plate （192 × 192 μm） and two cantilever beams （76 × 43 μm） which is about 4 μm thickness is tested. Since laser interferometry is not required, thermal effects on a test object can be avoided. Hence, the setup is relatively simple. Results show that the proposed method is a simple and effective approach for evaluating the dynamic characteristics of microstructures.     

Crystal growth, optical properties, and laser operation of Yb3+-doped NYW single crystal

Laser crystal Yb³⁺-doped NaY(WO₄)₂ (Yb:NYW) with excellent quality has been grown by Czochralski technique. The rocking curves from (400) plane of as-grown Yb:NYW crystal was measured and the full-width value at half-maximum was 19.92″. The effective segregation coefficients were measured by the X-ray fluorescence method. The polarized absorption spectra and the fluorescence spectra of Yb:NYW crystal were measured at room temperature. The fluorescence decay lifetime of Yb³⁺ ion in NYW crystal has been investigated. The spectroscopic parameters of Yb:NYW crystal are calculated and compared with those of Yb:YAG crystal. A continuous wave output power of 3.06 W at 1031 nm was obtained with a slope efficiency of 42% by use of diode pumping.     

决策树分类模型在工程项目评标风险预警中的应用

本文将数据挖掘中的决策树分类方法运用到工程项目评标数据分析,从200多个天津市工程项目招投标打分数据中,随机抽取15个招投标项目中的67个承包商的评标专家打分数据进行分析,得到中标承包商技术和商务评分分界点,进而得到工程项目潜在风险的预警阈值,然后借助因子分析辨识出风险来源并进行预警。     

A Selective RhI‐Catalyzed Substrate‐Controlled C−C Bond Activation of Benzyl Sulfonamide/Alcohol‐Tethered Alkylidenecyclopropanes

Benzyl sulfonamide/alcohol‐tethered alkylidenecyclopropanes undergo a rhodium‐catalyzed and substrate‐controlled selective C?C bond activation, producing three types of common organic structural units: benzo[c]azepine/oxepines, dihydronaphthalen‐1‐amines, and conjugated dienes. Epoxidation and aromatization of these products to construct two useful compounds have also been achieved.