Study on the nature of pressure signals in a bubbling fluidized bed

In this study on the nature of pressure signals generated by a deterministic or stochastic process in a bubbling fluidized bed, pressure fluctuation measurements were carried out in a 300-mm-diamet column at 0.090 m and 0.40 m above the distributor for different gas velocities. The method of detecting deterministic dynamic underlying pressure signals is proposed on the basis of predictability of pressure fluctuations. The deterministic nature of dynamics in fluidizing system was verified. The deterministic level of dynamics in fluidizing system was analyzed for different locations of pressure measurements and different gas velocities. Project supported by the Science and Engineering Foundation of SINOPEC, China (X599029)     

高压浓相粉煤气力输送特性及信息熵分析

在输送压力可达4.0MPa,固气比高达450kg/m3的高压气力输送试验台上,用氮气进行粉煤高压浓相气力输送试验研究.分别在不同的输送差压、煤粉湿度、浓度和速度等条件下进行了输送试验,考察操作参数对煤粉固气比等气力输送特征参数的影响,用信息熵分析试验过程中采集到的压力波动时间序列,探讨流动稳定性和流型变迁过程中信息化趋势,建立信息熵和流型之间的关系.结果表明:在输送差压增大的过程中,固气比和Shannon信息熵均增大;气体流量与Shannon信息熵和固气比之间呈现较好的规律性;不同流动形态的Shannon熵差异较大,不同流型之间的Shannon熵区分度较好.随着煤粉湿度的增大,煤粉质量流量和Shannon熵均降低.Shannon信息熵分析为研究高压浓相气力输送流型、流动稳定性及其转变特性提供了一种行之有效的方法.     

Denoising method for shear probe signal based on wavelet thresholding

Shear probe works under a tough environment where the turbulence signals to be measured are very weak.The measured turbulence signals often contain a large amount of noise.Due to wide frequency band,no...     

Determination of particle size distribution by multi-scale analysis of acoustic emission signals in gas-solid fluidized bed

Particle size distribution (PSD) is an important parameter in the process of fluidization, and it always plays a crucial role in a gas-solid fluidized system. A PSD model for on-line PSD determination based on acoustic emission (AE) measurement was developed according to the mechanism of particle collision with the inner wall of the cylinder and multi-scale wavelet decomposition analysis. This PSD model illuminates the quantitative relationship between the energy percentage of AE signals for different scales and the PSD, which indicates the feasibility of the application of the PSD model. Experiments were undertaken both in lab and plant gas-solid fluidized setup with polyethylene particles, and the parameters of the PSD model were calibrated and revised. The experimental conditions and results proved that the PSD model was suitable for on-line measurement and was sufficiently sensible and accurate. Concerning agglomeration, the PSD model also showed exact serviceability on detecting the onset of agglomeration by abnormal PSD, and the result agreed with that from the radiation method. Ultimately, AE measurement was found to be a reliable and credible means for understanding the PSD information that affects the behavior of a system, which can provide valuable guidance for practical applications.     

停车场有效泊位占有率变化特性及其短时预测模型

在某停车场泊位变化实测数据分析的基础上,建立了一个停车场有效泊位占有率短时预测模型.南京某停车场实测泊位数据分析表明,在不同的观测尺度上,停车场有效泊位占有率具有很强的周期性和相似性,但观测尺度越小,随机性越强.基于有效泊位占有率的这种短时变化特性,提出采用小波分析和加权马尔可夫组合模型对有效泊位占有率进行短时预测.首先,通过选择合适的小波函数对有效泊位占有率时间序列进行多分辨率的小波分解,并对低频信号与高频干扰信号分别进行重构,然后对重构后的基本信号和不同分辨率的干扰信号分别建立加权马尔可夫预测模型,最后对各自外推的预测结果进行合成,得到最终预测结果.实例分析表明,所提出的预测模型对有效泊位占有率的短时预测结果是有效的,但模型的预测精度依赖于有效泊位占有率数据库的实时更新.     

基于随机共振理论的低速重载齿轮故障诊断研究

基于随机共振理论,结合包络解调分析研究微弱低频幅值调制信号的增强与提取,并应用于低速重载齿轮的故障诊断.先将低频幅值调制信号输入到双稳非线性系统,运用信号自含噪声或外加噪声,实现随机共振现象,然后再进行包络解调分析.对模拟调幅信号和实测低速重载齿轮箱振动信号的分析结果,证实所提出方法的有效性和优越性.     

Blind separation of speech signals based on wavelet transform and independent component analysis

Speech signals in frequency domain were separated based on discrete wavelet transform （DWT） and inde- pendent component analysis （ICA）. First, mixed speech signals were decomposed into different frequency domains by DWT and the subbands of speech signals were separated using ICA in each wavelet domain; then, the permutation and scaling problems of frequency domain blind source separation （BSS） were solved by utilizing the correlation between adjacent bins in speech signals; at last, source signals were reconstructed from single branches. Experiments were car- ried out with 2 sources and 6 microphones using speech signals at sampling rate of 40 kHz. The microphones were aligned with 2 sources in front of them, on the left and right. The separation of one male and one female speeches lasted 2.5 s. It is proved that the new method is better than single ICA method and the signal to noise ratio is improved by 1 dB approximately.     

时频分析在局部放电信号分析中的应用

局部放电信号是非平稳性信号,具有时变频率。时频分析是分析和处理非平稳时变信号的有力工具,将时频分析技术应用于局部放电信号的分析与处理,能清楚地揭示信号的时变频谱特性,有利于对信号的特征提取,为局部放电信号的模式识别提供了一个更为准确、可靠的新方法。     

Classification of surface EMG signal with fractal dimension

INTRODUCTION Surface EMG signal recorded from the skin surface over limb muscles in the process of limmovement is called action surface EMG (ASEMGsignal. Containing the electrical and functional properties of limb muscle contraction and providing thinformation on the neuromuscular activity fromwhich ASEMG signal originates, ASEMG signal habeen widely applied in rehabilitation and the controlof prosthetic devices for the individuals with amputations or congenitally deficient limbs …     

Synergetic effects for p-nitrophenol abatement using a combinedactivated carbon adsorption-electrooxidation process

A novel fluidized electrochemical reactor that integrated advanced electrochemical oxidation with activated carbon (AC) fluidization in a single cell was developed to model pollutant p-nitrophenol (PNP) abatement. AC fluidization could enhance COD removal by 22%-30%. In such a combined process, synergetic effects on PNP and COD removal was found, with their removal rate being enhanced by 137.8% and 97.8%, respectively. AC could be electrochemically regenerated and reused, indicating the combined process would be promising for treatment of biorefractory organic pollutants.     

Synergetic effects for p-nitrophenol abatement using a combined activated carbon adsorption-electrooxidation process

A novel fluidized electrochemical reactor that integrated advanced electrochemical oxidation with activated carbon (AC) fluidization in a single cell was developed to model pollutant p-nitrophenol (PNP) abatement. AC fluidization could enhance COD removal by 22%-30%. In such a combined process, synergetic effects on PNP and COD removal was found, with their removal rate being enhanced by 137.8% and 97.8%, respectively. AC could be electrochemically regen erated and reused, indicating the combined process would be promising for treatment of biorefractory organic pollutants.     

From noise to information: a new technology of olefin polymerization fluidized bed reactor based on acoustic emission

The fluidized bed is widely used in many industrial processes because of its vigorous mixing and heat transfer properties. However, when heat transfer is blocked, the particles are easily melted and agglomerated, and even cause the industrial reactor to shut down. From the point of mechanism analysis, the process of explosive agglomeration is a typical meso-scale problem in the fluidized bed, and there is a complex evolution process between particle fluidization and reactor shutdown. Grasping the regulation of meso-scale structure is one of the major challenges faced by chemical engineering. Thus, in this background, the fluidized bed acoustic emission detection technology, agglomeration fault self-repair technology, and a direct scale-up technique of the fluidized bed mathematical model were invented. These technologies have provided strong reliability for stable operation and have been successfully applied in 14 sets of industrial plants.     

小波包分解在迎角传感器信号预处理中的应用

针对基于四象限压力传感器阵列的迎角测量方法中传感器信号受到干扰的问题。讨论了在其预处理中应用小波包变换进行信号分离提取的方法。根据小波包分解理论,对信号进行小波包分解,信号中频率不同的部分落在不同的尺度上,剔除反映干扰的变换尺度,提取出有用信息。结果表明,该方法可很好地提取信号的主要特征信息,也有效地去除了确定性干扰和随机噪声,与传统的信号滤波方法相比较具有明显的优点,同时为后续的信号处理奠定了基础。     

多功能循环流化床大型冷模实验装置的设计

在工程教育专业认证背景下,基于流态化工程课程教学改革,设计了一套与教学科研相结合的循环流化床大型冷模实验装置.循环流化床装置将理论教学与实践教学相结合,为学生提供流态化基本理论实验的同时,既夯实了学生的理论基础,又提高了学生的实践创新和解决工程问题能力.     

基于能量频谱分析法的电机故障诊断

基于定子电流信号进行异步电机故障诊断时,转子断条和匝间短路故障特征频率分量常常被电流的基频分量淹没,利用小波变换的能量谱对其进行诊断十分必要.考虑到小波分析在时域、频域都具有表征信号局部特征的能力,能通过时频窗的灵活变换来突出信号的不同频率成分;同时还有用小波处理非平稳信号的优越性,计算出各频带所占能量,进而获取能量分布的故障特征.实践表明,通过上述分析并从能量分布的角度出发,可以快速、准确地诊断出电机故障,诊断效果好于傅里叶分析;同时也提供了一种思路,为电机故障在线实时诊断提供了理论依据.     

基于生物信号的远程学习过程监控系统研究

学习过程监控是远程教育的关键环节。学习者在不同学习状态下,脑电波、脉搏、血压、皮温等生物信号会有所不同。基于生物信号采集的远程学习过程监控系统,利用生物传感器采集学习者在线学习时的生物信号,一方面将不同学习者呈现出的生物信号特征分类,建立生物信号分类数据库;另一方面,将动态采集的学习者生物信号通过蓝牙等无线传输方式输入学习终端,再通过Internet输入到远程学习管理中心,通过系统分析软件将采集到的生物信号与学习者生物信号分类数据库进行对比,以获得学习者的实时学习状态,为教师干预和学习者学习提供及时、有针对性的支持服务。基于眼动信号监控学习者疲劳状态的实验证明,利用生物信号采集技术对远程学习过程进行监控,有助于管理者掌握学习者的学习状态,并据此提供个性化学习过程和学习资源支持服务。     

Synergetic effects for p-nitrophenol abatement using a combined activated carbon adsorption-electrooxidation process

A novel fluidized electrochemical reactor that integrated advanced electrochemical oxidation with activated carbon (AC) fluidization in a single cell was developed to model pollutant p-nitrophenol (PNP) abatement. AC fluidization could enhance COD removal by 22%–30%. In such a combined process, synergetic effects on PNP and COD removal was found, with their removal rate being enhanced by 137.8% and 97.8%, respectively. AC could be electrochemically regenerated and reused, indicating the combined process would be promising for treatment of biorefractory organic pollutants. Project (No. 20306027) supported by the National Natural Science Foundation of China     

夹层梁脱层与裂纹检测试验的小波分析

探索采用小波分析方法,对FRP(玻璃钢)夹层梁的脱层损伤和裂纹损伤检测分别进行试验研究。利用智能结构技术监测夹层梁结构的应变响应信号,对应变响应信号进行复一阶高斯小波变换,通过分析小波变换系数中包含的奇点特征,对梁上的损伤信息进行了有效的识别,监测结构的损伤状况。研究了脱层损伤和裂纹损伤发生在不同损伤程度时的小波变换方法识别。研究表明,本文方法对有效地监测FRP夹层梁是否存在损伤,损伤类型,损伤位置以及损伤程度的定量判定,均能提供较好的参考价值。     

Synthesized Multi-Method to Detect and Classify Epileptic Waves in EEG

In order to sufficiently exploit the advantages of different signal processing methods, such as wavelet transformation (WT), artificial neural networks (ANN) and expert rules (ER), a synthesized multi-method was introduced to detect and classify the epileptic waves in the EEG data. Using this method, at first, the epileptic waves were detected from pre-processed EEG data at different scales by WT, then the characteristic parameters of the chosen candidates of epileptic waves were extracted and sent into the well-trained ANN to identify and classify the true epileptic waves,and at last, the detected epileptic waves were certificated by ER. The statistic results of detection and classification show that, the synthesized multi-method has a good capacity to extract signal features and to shield the signals from the random noise. This method is especially fit for the analysis of the biomedical signals in biomedical engineering which are usually non-placid and nonlinear.     

Wind-induced internal pressure fluctuations of structure with single windward opening

INTRODUCTION The wind loads of the exterior-protected con-struction of buildings are decided based on the pres-sure difference between the external and internalpressure. The failures of low-rise building roof andwall in high wind events are caused by a combinationof large internal and external force acting in the samedirection. A large opening in the building envelope,caused by the failure of a door or window may gen-erate large internal pressures in strong wind condi-tions, and therefore …