发泡条件对炭泡沫孔泡结构的影响

以AR中间相沥青为原料,在中间相沥青裂解行为的基础上,利用自发泡工艺制备了中间相沥青基炭泡沫.重点研究了发泡过程中形核温度、初始压力以及固化温度对炭泡沫孔泡结构的影响规律.结果表明:随着形核温度的升高,炭泡沫的孔径变大,开口孔隙率升高.随着初始压力的升高,炭泡沫的孔径减小,开口孔隙率降低.随着固化温度的提高,炭泡沫的孔泡结构由椭圆形变为圆形,开口孔隙率升高.     

Synthesis and properties of ferro- and antiferroelectric esters with a chiral centre based on (S)-(+)-3-octanol

A homologous series of chiral three ring esters were synthesised and their properties were studied. The materials possess an antiferroelectric phase (SmC_A*) or/and a ferroelectric phase (SmC*), which was confirmed by observations of microscopic textures using a polarising optical microscope. The phase transition temperatures and enthalpies were checked by differential scanning calorimetry. The helical pitch was measured by a spectrophotometry method. For all cases the helix is right-handed, in the antiferroelectric phase the helical pitch increases with temperature, and in the ferroelectric phase the helical pitch is short.     

Impact of molecular structure of smectogenic chiral esters (3FmX1X2r) on vibrational dynamics as seen by IR and Raman spectroscopy

Smectogenic chiral esters with three-ring rigid core were examined by infrared and Raman spectroscopy. These compounds differ in the type of chiral centre, length of non-chiral chain and substitution of phenyl ring by fluorine atoms. The influence of molecular structure on the type of handedness of helical structure, as well as the shift and split of absorption bands on IR and Raman spectra were determined. The change of the length of non-chiral terminal chain has the most significant influence on the type of helical twist sense. All considered structural elements of tested compounds have the biggest influence on the value of wavelength of vibrational bands related to the carbonyl group located in the rigid core.     

Assessing the Maturity of Crude Petroleum Oils Using Total Synchronous Fluorescence Scan Spectra

There have been many applications of fluorescence methods for the analysis of crude petroleum oils down through the years. However, none of these studies has yielded a robust qualitative or quantitative method for quantifying the chemical composition, or assessing the maturity of crude oils. Simple fluorescence parameters such as lifetime, intensity, and intensity ratios do not correlate well with chemical composition particularly for medium weight crude oils [A. G. Ryder, T. J. Glynn, and M. Feely (2003). Proc. SPIE-Int. Soc. Opt. Eng. 4876, 1188-1195.]. A better approach may be to use the Total Synchronous Fluorescence Scan (TSFS) method to fully interrogate the complex chemical composition of the oils [D. Patra and A. K. Mishra (2002). Anal. Bioanal. Chem. 373, 304-309.]. We present TSFS spectra from 18 crude petroleum oils of varying composition, sourced from around the world. The TSFS plots of these oils are very complex, with the contours being spread over the full 250-700 nm wavelength range (lambda(ex)) and 40-200 nm wavelength interval (delta lambda) sampled. The 3-D contour maps tend to two contour concentrations one at lambda(em) < 300 nm, delta lambda = 120-200 nm, and a second near lambda(ex) approximately 380-400 nm, delta lambda = 40-60 nm. The first feature represents fluorescence emission originating mainly from energy transfer processes with the second, longer wavelength feature originating from fluorescence emission generated by a higher proportion of direct excitation as opposed to emission resulting from energy transfer. The topography of the 3D contour plots is therefore influenced by the balance between energy transfer and direct fluorescence emission, which is governed by the chemical composition of the crude oils. We discuss how the gross chemical composition affects TSFS spectra and how TSFS can be used to assess oil maturity with a view to developing quantitative methods.     

国际油价上涨对中国经济的影响及应对措施

分析了近年来国际油价上涨的原因及对中国经济的影响，提出了建立风险预警系统、强化国内外资源勘探开发、建立石汕储备、加强对节油工作的宏观管理与协调等应对措施，以化解石油风险，保障国家石油安全。     

过渡音的基音周期检测方法

针对传统的基音估计算法不能适用于过渡音的问题，提出中心偏离函数及基于中心偏离函数的基音周期检测算法。该算法主要通过划分语音子带来搜索最小中心偏移量，较准确地确定过渡音的基音周期。介绍了该算法的设计思想和实现过程，并给出代表性的实验结果，将其结果与MBE算法所检测到的基音周期进行比较。研究结果表明：采用所提出的中心偏离函数和时域削波方法相结合来搜索基音周期，能够有效地克服传统方法的不足，降低误判率，提高基音周期的估计精度。     

基于语音合成法的汉语人名语音库的设计应用

采用语音合成方法完成了汉语人名语音库的设计.声母部分直接采用录音样本,而韵母部分则通过激励声道频率响应函数来合成语音,然后通过声韵母拼接来实现人名语音合成,以此建立人名语音库.可以实现各种可能人名语音的合成,适合应用于多种电子自助系统中.     

一种基于半自动弧焊发电机外部电流/电压的控制方法

半自动弧焊发电机通常工作在平特性或降特性状态,工作于平特性时要求电压基本恒定,工作于降特性时要求电流基本恒定。数据采集模块采集焊接电流/电压,并送单片机分析处理,利用模糊控制理论,通过计算隶属度把电流/电压信号分成过强、强、中、弱和微弱5类,不同类型采用不同的控制策略来控制PWM信号的占空比,PWM信号调节发电机励磁回路电流,以达到对发电机输出电流和电压的控制,从而实现对半自动弧焊发电机的焊接电流/电压进行控制。     

Detection of water in petroleum inclusions and its implications

As water phase is rarely observed in petroleum in- clusions under microscope, and a little geologic and geochemical evidence responsible for whether water exists in petroleum inclusions or not is present, there is a dispute in the past two decades: water …     

声码器半解码参数用于说话人身份确认

面向通信领域广泛使用的线性预测声码器，设计了一种不经过“解码—特征提取”过程，而直接由传输码流截取说话人特征的方法，并针对宽带自适应多码率声码器（ANN-WB）建立了与文本无关的话者确认系统．系统采用基于概率统计模型的GMM-UBM结构，以LPC倒谱作为主要的话者特征矢量，并加入基音衍生参数以提高确认性能．实验表明，该系统在运算速度提高一个数量级的情况下，达到了与基于重建语音的话者确认系统相接近的性能，且对码率失配具有良好的鲁棒性．