A new high frequency dynamic mechanical analysis system: An approach to direct high frequency testing of tire tread rubber

Dynamic Mechanical Analysis (DMA) systems are measurement devices for obtaining master curves and complex modules of viscoelastic materials, such as rubbers. The conventional DMAs measurement systems in market have several limitations, which restrict their ability for operating at high frequencies. Thus, Williams, Landel and Ferry (WLF) relation is used to produce master curves and predict the material properties at high frequencies. In conventional DMAs, experiments are done in a range of temperatures, and then a master curve is made for a chosen reference temperature by shifting the measurements data to high frequencies. Therefore, the obtained results, which are not based on direct measurements, can be inaccurate. In order to overcome this problem a new simple shear high-frequency DMA (HFDMA) system is designed and built to directly measure the dynamic mechanical properties of viscoelastic material at high frequencies and the strain levels sufficient for tire manufacturers. The new HFDMA can be used to test any viscoelastic materials which have glass transmission temperature (Tg) lower than room temperature (about 23 °C) such as the Styrene-butadiene rubber (SBR). The SBR is the base material for tire tread. The designing process of this new HFDMA is presented in this paper. The rubber specimen shape is chosen by taking into account the shear elastic wave effect, bending, buckling effect and heat generation in the specimen. The repeatability test is accomplished to ensure that the results obtained from the new HFDMA are repeatable and the repeatability uncertainty is about 0.04%. The new HFDMA is validated by comparing to the direct test results of conventional DMA at 100 Hz. The direct high frequency (5 kHz) complex shear modulus and damping factor are compared with the master curve of the conventional DMA developed by the use of WLF relation for SBR. This comparison revealed that the complex shear modulus and damping factor of the SBR obtained from the HFDMA at 5 kHz and 0.05% strain amplitude are about 7% and 6.5% higher than those obtained from the conventional DMA, respectively.     

Phytochemical Analysis and Habitat Suitability Mapping of Glycyrrhiza glabra L. Collected in the Hatay Region of Turkey

The growth and quality of licorice depend on various environmental factors, including the local climate and soil properties; therefore, its cultivation is often unsuccessful. The current study investigated the key factors that affect the contents of bioactive compounds of Glycyrrhiza glabra L. root and estimated suitable growth zones from collection sites in the Hatay region of Turkey. The contents of three bioactive compounds (glycyrrhizic acid, glabridin, and liquiritin), soil factors (pH, soil bearing capacity, and moisture content), and geographical information (slope, aspect, curvature, elevation, and hillshade) were measured. Meteorological data (temperature and precipitation) were also obtained. An analysis of variance (ANOVA) and multivariate analysis of variance (MANOVA) were performed on the data. The soil bearing capacity, moisture content, slope, aspect, curvature, and elevation of the study area showed statistically significant effects on the glycyrrhizic acid and liquiritin contents. A habitat suitability zone map was generated using a GIS-based frequency ratio (FR) model with spatial correlations to the soil, topographical, and meteorological data. The final map categorized the study area into four zones: very high (15.14%), high (31.50%), moderate (40.25%), and low suitability (13.11%). High suitability zones are recommended for further investigation and future cultivation of G. glabra.     

垂直悬挂质点弹簧系统的振动

讨论了振动的振幅与周期的变化规律,给出了当质点质量m0与弹簧质量m之比趋于零与趋于无穷大以及系统水平放置时的振动解.     

基于LPC2210和SSD1339的PM-OLED驱动控制电路

为了避免早期无源矩阵有机电致发光器件驱动控制电路的一些缺陷,如:"串扰"和"交叉"效应以及电路连接比较复杂,用两种方法实现了基于飞利浦公司生产的LPC2210控制芯片和晶门科技公司的SSD1339驱动芯片的驱动控制电路。首先介绍了有机电致发光器件的结构和发光原理以及芯片SSD1339和LPC2210的主要的特点;分析和比较了SSD1339的8080系列并行口和LPC2210外部存储控制单元的读写时序;分别利用LPC2210的通用输入输出单元和外部存储控制单元,成功的控制SSD1339驱动128RGB×128点阵有机电致发光屏。实验结果表明:两种方法不仅可以有效地克服早期驱动控制电路的缺陷,而且可以使有机电致发光屏显示出高质量的图片;用外部存储控制单元实现的驱动控制电路,可以实现约80 Hz的驱动帧频;而使用通用输入输出单元实现的驱动控制电路,可以单步跟踪数据的传输,因此它具有方便查错的优势。本次实验为在不同的集成环境下无源矩阵有机电致发光器件驱动控制电路的设计奠定基础。     

负五阶非线性下预啁啾高斯光脉冲的啁啾和频谱

为探究光纤负五阶非线性和光脉冲预啁啾对高斯光脉冲频率啁啾和频谱的综合影响,在忽略光纤色散的情况下,利用包含三五阶非线性的扩展非线性薛定谔方程,计算和分析了啁啾高斯脉冲的频谱和总啁啾。结果表明,脉冲无预啁啾时,负五阶非线性的存在可使脉冲频率啁啾的形状由单“S”形变为双“S”形,并使脉冲的中心附近由正啁啾变为负啁啾。此外,负五阶非线性的存在使预啁啾对脉冲频谱的影响发生了较大的变化。预啁啾与非线性所致啁啾叠加后对脉冲频谱的谱峰数目影响较小,而对能量在各个谱峰上的分布影响较大,在某些最大非线性相移下,甚至会出现总啁啾减小使谱峰值数目增加的情况。该研究对光开关、光脉冲压缩以及光纤通信系统等领域的深入发展具有一定的指导意义。     

毛细管电泳法快速测定复方地芬诺酯片中的地芬诺酯和阿托品

建立了毛细管电泳高频电导法同时测定地芬诺酯和阿托品的方法。探讨了缓冲溶液、有机溶剂添加剂、分离电压和进样条件以及毛细管内径和长度等因素对分离检测的影响。在电泳介质为10.0mmol/L乳酸-15.0?H5OH、分离电压20.0kV的优化条件下,6min内即可实现地芬诺酯和阿托品的同时分离检测,线性范围分别为5.00~500和2.00~320mg/L;检出限分别为3.0和1.0mg/L。     

Theil Entropy as a Non-Lineal Analysis for Spectral Inequality of Physiological Oscillations

Theil entropy is a statistical measure used in economics to quantify income inequalities. However, it can be applied to any data distribution including biological signals. In this work, we applied different spectral methods on heart rate variability signals and cellular calcium oscillations previously to Theil entropy analysis. The behavior of Theil entropy and its decomposable property was investigated using exponents in the range of [−1, 2], on the spectrum of synthetic and physiological signals. Our results suggest that the best spectral decomposition method to analyze the spectral inequality of physiological oscillations is the Lomb–Scargle method, followed by Theil entropy analysis. Moreover, our results showed that the exponents that provide more information to describe the spectral inequality in the tested signals were zero, one, and two. It was also observed that the intra-band component is the one that contributes the most to total inequality for the studied oscillations. More in detail, we found that in the state of mental stress, the inequality determined by the Theil entropy analysis of heart rate increases with respect to the resting state. Likewise, the same analytical approach shows that cellular calcium oscillations present on developing interneurons display greater inequality distribution when inhibition of a neurotransmitter system is in place. In conclusion, we propose that Theil entropy is useful for analyzing spectral inequality and to explore its origin in physiological signals.     

参变过程中的群速延迟对晶体匹配长度的影响

基于能量守恒和三波耦合波方程,建立了超短脉冲在参变过程中二次谐波产生时的I类和II类相位匹配条件、基波与谐波之间的群速延迟时间、以及群速失配对晶体长度限制的理论基础。以负单轴非线性光学晶体CsLiB6O10为例,分析和数值计算了超短脉冲宽度为100fs时,谐波的群速匹配长度随基波波长变化的规律。研究结果表明在I类相位匹配条件下,基波波长为642nm时,群速延迟最小,相应的群速匹配晶体长度最长为19.1mm;在II类相位匹配条件下,基波波长为767nm,群速延迟最小,群速匹配长度最长为0.89mm。     

分辨力增强技术的频谱分析

离轴照明和衰减型相移掩模作为重要的分辨力增强技术,不仅可以提高光刻的分辨力,同时还可以改善成像焦深,扩大光刻工艺窗口,实现65~32 nm分辨成像。从频谱的角度分析了离轴照明和衰减型相移掩模对成像系统交叉传递函数和像场空间频率分布的影响,研究这两种技术的物理光学本质,由此进一步优化光学成像系统设计、分辨力增强技术和确定设备使用的参量。对分辨力增强技术的频谱分析研究表明,分辨力增强技术通过调整像场频谱分布,改善了光学光刻的图形质量。对于65 nm密集图形,离轴照明和相移掩模结合后可以使成像衬比度最高达到0.948,工艺窗口在5%曝光范围内焦深达到0.51μm。     

用极值频率法分析数字全息的记录条件

根据全息理论,通过分析全息图光栅结构的极值频率,利用抽样定理以及频谱分离条件,分析了离轴菲涅耳全息的记录条件,得到了不同于以往文献的最小记录距离及参考光源设置表达式,并做了计算机模拟验证.结果表明：用该方法推得的离轴菲涅耳全息最小记录距离和参考光设置表达式是正确的.只有同时满足抽样条件和频谱分离条件,才能得到高质量的再现像.