酒石酸镁对水合草酸钙晶体生长的调控作用

本文在凝胶模拟体系中研究了Mgtart对草酸钙生长、 聚集和晶型、 晶相等的影响, 以期阐明Mgtart防治泌尿系结石形成的可能机理, 为临床医学提供参考.     

Analysis of viscosity abnormalities of polyelectrolytes in dilute solutions

It was found that the interface effects in viscous capillary flow influenced the process of viscosity measurement greatly,and the abnormal viscosity behaviors of polyelectrolytes as well as neutral polymers in dilute solution region were ascribed to interface effect.According to this theory,we have reviewed the previous viscosity data of derivatives of poly-2- vinylpyridine reported by Maclay and Fuoss first.Then,the abnormal viscosity behaviors of a series of sodium polystyrene sulfonate samples with various molecular weights in dilute aqueous solutions were studied further.The solute adsorption behaviors and structural information of polymers have been discussed carefully.     

“元素化学实验”中的“异常”现象(一)--Mn元素化学实验中的“异常”现象及其探析

大一学生在“元素化学实验”教学过程中,对反应条件如温度、催化剂、酸度、浓度或试剂用量等因素的影响考虑不周,可能出现某些实验现象和预想的或理论分析的结果不一致的“异常”现象。本文就学生在Mn元素化学实验过程中遇到的一些“异常”现象进行分析和总结,借助生动直观的演示实验,引导学生探究“异常”现象产生的可能原因和直观认识反应条件对反应结果的影响,培养学生的观察、分析、判断、归纳、推理和解决实际问题的能力。     

巡天光谱中拼接异常光谱的自动检测和异常分级方法

拼接异常是光谱在红蓝两端拼接区域表现出的光谱连续性差的一种现象。在LAMOST的光谱处理中,仪器的稳定性、观测条件以及获得的响应函数等问题都是造成拼接异常的原因。光谱拼接是否正常对于光谱发布等后续工作的质量有重要影响。提出一种拼接异常光谱的自动检测方法,有效地提高了工作效率。该研究可以为LAMOST数据提供一个自动的标记,来评价拼接质量,也可以为用户提供一个使用数据时的选择。该方法首先将待测光谱进行流量归一化、去除钠线等预处理,并将其分为红蓝两端;然后对红蓝两端分别进行拟合;最后对两条拟合曲线,选取一系列等波长间隔的点,计算在这些点处的流量差值,得到所有流量差值的均值,标准差,并且计算两条曲线积分面积的差值;基于上述统计量,提出了一个判断光谱是否异常及其异常程度的评价函数。大量的实验证明,该方法具有良好的拼接异常光谱检测效果。     

Abnormal positive thermal expansion in Mo substituted ZrW2O8

ZrW₂O₈ displays the unusual property of an isotropic bulk contraction in volume as a function of temperature. We report here on the positive thermal expansion (PTE) property caused by substituting Mo for W sites in ZrW₂O₈ at room temperature. The room temperature crystal structure of ZrW_2−xMo_xO₈ compounds, which were synthesized using a low temperature route, could be divided into ordered phase with α-ZrW₂O₈ structure (0≤x≤0.5) and disordered phase with β-ZrW₂O₈ (0.5<x≤1.5) and c-ZrMo₂O₈ structure (1.5<x≤2). ZrW_2−xMo_xO₈ adopting β-ZrW₂O₈ structure shows abnormal PTE property at room temperature due to the existence of water molecules, while ZrW_2−xMo_xO₈ adopting the other two structures (α-ZrW₂O₈ and c-ZrMo₂O₈) shows negative thermal expansion (NTE) property from room temperature until decomposition for α-ZrW₂O₈ structure or trigonal phase transition for c-ZrMo₂O₈ structure. The reason lies in the fact that the oxygen migration caused by the Mo substitution leads to the re-arrangement of W(Mo)O₄ tetrahedra lying along the 3-fold axis, only particular W/Mo ratio (0.5<x≤1.5) produces a special crystal structure, which allows the entrance of water molecules.     

呼吸声分类技术研究及检测系统设计*

患有呼吸问题的病人由于呼吸道腺体不受意识控制、异物或者其本身肺部病变等原因会出现呼吸异常。医护人员通过病人的呼吸状况可以找寻和分析病人出现这种呼吸状况的原因。而以往呼吸声的诊断方式是专业的医护人员通过使用听诊器对病人进行肺部听诊。但是听诊的结果取决于医护人员的经验与相关参数。在初级诊断治疗阶段,初级医生识别听诊声的效率以及准确率很低,一般从20%到80%不等。因此会存在10%到20%的高误诊率（漏诊、错诊和延误）。本文提出了一种利用PVDF薄膜传感器提取语声特征的检测系统,该检测系统根据病人发出声音的不同,提取呼吸声特征值判断病人的呼吸状况。通过PVDF传感器采集的微弱呼吸声再经过KNN算法分类之后其识别率可达90.6%,对于细分种较类多的湿罗声,其识别率在80.2%左右。综上表明相比于传统听诊方式通过PVDF传感器采集识别的结果具有更高的准确性和可靠性,其判断呼吸状况的结果可以为医护人员提供参考,更好的为患有呼吸疾病的病人提供监测。     

Geometry of rank 2 distributions with nonzero Wilczynski invariants

In the famous 1910 “cinq variables” paper Cartan showed in particular that for maximally nonholonomic rank 2 distributions in ?⁵ with non-zero covariant binary biquadratic form the dimension of the pseudo-group of local symmetries does not exceed 7 and among such distributions he described the one-parametric family of distributions for which this pseudo-group is exactly 7-dimensional. Using the novel interpretation of the Cartan covariant binary biquadratic form via the classical Wilczynski invariant of curves in projective spaces associated with abnormal extremals of the distributions [4, 27, 28] one can generalize this Cartan result to rank 2 distributions in ?ⁿ satisfying certain genericity assumption, called maximality of class, for arbitrary n ≥ 5.

In the present paper for any rank 2 distribution of maximal class with at least one nonvanishing generalized Wilczynski invariants we construct the canonical frame on a (2n — 3)-dimensional bundle and describe explicitly the moduli spaces of the most symmetric models. The relation of our results to the divergence equivalence of Lagrangians of higher order is given as well.     

基于3G-ASCX的小型飞行器异常导航信号检测系统设计

传统方法在异常导航信号信噪比较低时对小型飞行器异常导航信号的检测效果不理想。设计并实现了一种基于3G-ASCX的小型飞行器异常导航信号检测系统,硬件设计时着重于ASCX传感器模块、异常导航信号检测模块、主控基站模块、3G/GPRS传输模块的研究,3G/GPRS传输模块的硬件设计中,通过功耗低体积小的CC1100完成异常导航信号的收发,传输过程中通过芯片STC12C5410AD完成电容的平衡转换,选取了MC3486进行电压的转换,最终实现异常信号数据的安全快速传输;软件设计中,系统软件流程设计及异常导航信号检测模块软件设计,最后进行仿真实验,实验结果证明,相比传统系统,所设计系统检测到的小型飞行器异常导航信号同实际测量的异常导航信号具有较高的匹配度,与实际值相比,误差小于1dB,适合推广使用。     

Amphoteric refraction exhibited by anisotropic crystals

Amphoteric refraction of light ray at the interface between isotropic materials and anisotropic materials is analyzed. Depending on the incident angle, the refractive light ray can either refract positively or negatively. This amphoteric refraction phenomenon can be quite prevalent when the difference of the two principal refractive indices is large. The reflectance under various incident angles has also been calculated, and an experimental demonstration with a calcite crystal in air is presented.     

某商用车怠速油底壳异响问题分析研究*

针对产品开发过程中某柴油车型发动机油底壳怠速时“呜呜”异响问题,通过噪声与振动的测试及仿真分析,对油底壳异响原因进行分析。结果表明,怠速时机油泵的工作激励频率与油底壳模态频率耦合,形成“呜呜”声,并通过油底壳表面辐射出来。进一步实验研究表明,随着机油温度的升高,机油泵功率、工作激励幅值会逐步减小,异响逐步减小。同时实验研究表明,机油量对油底壳模态频率有影响,油底壳内机油加注量越多,油底壳模态频率越低,油底壳表面振动幅值及异响均逐步减小。针对该异响问题,明确该发动机机油加注上限及下限时油底壳对应频率范围后,通过优化怠速转速,提高油底壳模态频率等使机油泵激励频率与油底壳模态频率避频,解决了该异响问题。