工业噪声对脑认知影响的功率谱估计分析

为明确工业噪声对大脑认知的负面影响,采集火电厂球磨机的工业噪声,征集10名在校大学生在90 dB(A)的稳态工业噪声状态下及安静状态下的32导联脑电图(EEC).采用傅里叶变换方法进行频域分析,提取δ频段、θ频段、α1频段、α2频段和β频段功率谱,并进行统计分析.结果 表明:噪声环境与静音环境相比较,被试在δ频段、θ频...     

Is carbon dioxide emission convergence in the ten largest economies?

This study applies stationary test with a flexible Fourier function proposed by Enders and Lee (Enders, W. and J. Lee. 2012. Oxford Bulletin of Economics and Statistics 74:574–99) to test the validity of carbon dioxide emission to assess its convergence, and the rationality of the existing policies in the 10 largest economies of the world. We find that our approximation has higher power to detect smooth breaks than the linear method, as the true data generating process of carbon dioxide emission convergence is in fact a stationary nonliner process. We examine the validity of carbon dioxide emission from the nonlinear point of view and provide robust evidence that clearly indicates that carbon dioxide emission is convergence in most countries, not depending on their development pattern. It implies that the existing policies in most countries are rational, and the United States, Japan, and Germany need more efforts in reducing the carbon dioxide emission.     

压力脉冲波法复杂天然气管道堵塞检测实验研究*

为了解决复杂天然气管道堵塞定位难题,快速定位出堵塞位置,提出利用压力脉冲波法检测复杂管道堵塞。改造搭建长18.1 m、包含17个三通结构的压力波堵塞检测实验台,进行不同堵塞率以及气液混输管道的堵塞定位实验。结果表明:管道三通会引起频率范围为150~200 Hz的高频反射波,利用FFT谐波变换方法可以有效地对原始信号进行滤波分析,更利于对堵塞定位分析。在堵塞率100%时,定位误差为1.07%;在堵塞率50%时,定位误差最大,达到1.93%;对于含液率8%的气液混输管道,100%堵塞时,定位误差为0.48%。研究结果有效地证实了压力脉冲法检测复杂输运管道堵塞的可行性,可为该方法的现场应用提供指导和数据支撑。     

废聚氨酯硬泡热处理特性及产物检测分析

利用热重分析仪和管式炉研究了废弃聚氨酯硬泡热处理特性并对热处理产物进行了检测分析。研究结果表明,废聚氨酯硬泡热处理过程呈单一剧烈失重峰,热失重主要发生在200～440℃之间,600℃热分解基本完成;FTIR谱图初步分析发现加热分解过程中有大量CO和CO2产生,且热处理过程中可能有O-H、C-H、C=O及带有苯环的物质生成。通过GC/MS检测分析结果显示热处理液体产物中检出多元醇以及苯胺、p-苯胺、苯甲腈等多种芳香类化合物,气体产物以低碳的烷烃和烯烃为主,可见FTIR和GC/MS分析结果有很好的一致性。研究结果显示,气体产物检测出有机氯化合物,这可能是聚氨酯硬泡生产过程中加入的氟利昂类发泡剂所致。     

GENERATING STREAMFLOW SEQUENCES WITH TREND AND CYCLICAL MOVEMENTS1

ABSTRACT: A first-order autoregressive model had been modified with the trend and cyclical movements to generate the streamflow sequences. Three main portions were involved in this modified model, i.e., six-year cycle with trend changing; six-year cycle without trend changing; and both annual and six-year cycles with trend changing. The synthetic sequences of monthly streamflow sequences were compared with the historical records obtained from the Kissimmee River basin by using the Chi-Square test for goodness-of-fit. The results indicated that the newly proposed model has a better solution than the original model because the trend and cyclical movements involved in generating sequences are much closer to the historical records.     

"傅里叶级数部分和逼近和函数"的动态演示

本文主要介绍利用多媒体创作软件Authorware制作教学演示课件，实现对“傅里叶级数的部分和逼近和函数”的过程的形象演示。     

数字地震记录中干扰波的排除

本文介绍了用MATLAB工具软件实现对数字信号进行频谱分析和设计IIR数字滤波器的方法,对数字地震记录中的干扰波进行谱分析和排除,实现了目标要求。     

串联工氨解脱离子交换法处理味精生产中的等电点废母液

采用四只串联的离子交换柱连接、交替吸附味精生产等电点废母液中残留的谷氨酸，通氨洗脱树脂吸附的谷氨酸，回收谷氨酸生产味精。这一技术可使味精产率提高4．5％，污染物COD排放量削减25％，经济效益和环境效益十分显著。     

垃圾衍生燃料热重-红外联用法的热解特性

实验以中小城市垃圾典型组分合成RDF,利用热重-傅立叶变换红外光谱(TG-FTIR)联用法对其热解特性进行了研究,并求解了RDF热解反应动力学参数。结果表明城市垃圾合成RDF具有较高的热值,煤的混入具有良好的助燃效果,单一组分及RDF混合组分的热解服从动力学基本方程表征的规律,可以用来获得动力学参数。     

A preliminary experimental feasibility case study of energy upgrade of pellets of lignite and plastic waste mixtures

The calorific value enhancement of lignite by briquetting with novolac resin and plastic wastes is discussed in this work. Mixtures of several types of lignite with novolac as binder, with or without polypropylene, were manufactured in the form of pellets by curing. Pellets were pyrolyzed at 300°C and 500°C, and weight losses were determined. Chemical transformations during curing were studied by Fourier‐transform infrared spectroscopy, and the corresponding changes in the microstructure of the pellets were investigated by optical microscopy. Specimens of cured pellets were tested for their impact resistance index (IRI) and water resistance index (WRI). The incorporation of polypropylene in the pellets leads to an increase of IRI and a decrease of WRI. The calorific value was measured for both cured and pyrolyzed pellets. All pellets exhibit increased lower calorific value compared with raw lignite, indicating an upgrade of their energy content.