Application of the blind source separation method to feature extraction of machine sound signals

As the result of vibration emission in air, a machine sound signal carries important information about the working condition of machinery. But in practice, the sound signal is typically received with a very low signal-to-noise ratio. To obtain features of the original sound signal, uncorrelated sound signals must be removed and the wavelet coefficients related to fault condition must be retrieved. In this paper, the blind source separation technique is used to recover the wavelet coefficients of a monitored source from complex observed signals. Since in the proposed blind source separation (BSS) algorithms it is generally assumed that the number of sources is known, the Gerschgorin disk estimator method is introduced to determine the number of sound sources before applying the BSS method. This method can estimate the number of sound sources under non-Gaussian and non-white noise conditions. Then, the partial singular value analysis method is used to select these significant observations for BSS analysis. This method ensures that signals are separated with the smallest distortion. Afterwards, the time-frequency separation algorithm, converted to a suitable BSS algorithm for the separation of a non-stationary signal, is introduced. The transfer channel between observations and sources and the wavelet coefficients of the source signals can be blindly identified via this algorithm. The reconstructed wavelet coefficients can be used for diagnosis. Finally, the separation results obtained from the observed signals recorded in a semi-anechoic chamber demonstrate the effectiveness of the presented methods .     

倒虹吸管管径计算的迭代法

本文先将倒虹吸管的管径计算公式整理成等式左边只含管径的一次方法，右边含有管径高阶非线性的迭代函数，然后证明该迭代函数收敛，最后利用数学迭代原理给迭代函数右边赋初值，计算左边的管径。继续迭代下去，就能求出倒虹吸管的管径。     

Application of boundary element method to 3-D problems of coupled thermoelasticity

This paper deals with a new boundary element method for analysis of the quasistatic problems in coupled thermoelasticity. Through some mathematical manipulation of the Navier equation in elasticity, the heat conduction equation is transformed into a simpler form, similar to the uncoupled-type equation with the modified thermal conductivity which shows the coupling effects. This procedure enables us to treat the coupled thermoelastic problems as an uncoupled one, A few examples are computed by the proposed BEM, and the results obtained are compared with the analytical ones available in the literature, whereby the accuracy and versatility of the proposed method are demonstrated.     

步进梁式炉的运动研究

对国内引进的、用于粉末冶金的步进梁式炉的运动,以图解法和解析法进行了分析,并对运动参数进行了理论推导和计算。本研究结果,对解决步进粱式炉的运动故障以及进行新型设计提供了有效的理论分析和计算依据。     

Time‐dependent heat transfer coefficient of a wall

A time‐dependent coefficient of heat transfer is proposed for the computation of thermal power required, so that a room temperature reaches a desired value within a given time. A mathematical formulation of the room heating transient phenomenon is constructed in a dimensionless form. Using an integral approximate solution an analytical expression for this coefficient is provided and it is verified by diagrams adopted by DIN 4701. Copyright © 2003 John Wiley & Sons, Ltd.     

Solving regularized least squares with qualitatively controlled adaptive cross‐approximated matrices

The adaptive cross‐approximation (ACA) technique is applied to accelerating an inverse‐problem solver that estimates charge distribution on a dielectric spacer. The ACA generates an approximated system‐matrix that enables us to carry out high‐speed inverse calculation. We designed an approximation procedure based on ACA with some additional concepts, that is, (a) partitioning of matrix based on algebraic information, (b) approximation quality control based on matrix norms, and so on. The tested solver (LSQR for regularized least squares) with ACA demonstrates about 10 times faster performance than that without ACA. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(3): 10–18, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20326     

浆砌石衬砌在渠道防渗中的应用及对策

总结了浆砌石应用的历史,介绍了浆砌石的结构特性和施工工艺,从造价方面、防渗效果及施工三方面分析了浆砌石衬砌主要存在的问题,并提出了相应的解决对策,指出浆砌石衬砌在渠道防渗应用中应控制施工质量,从而更好地提高防渗效果。     

FEM model of the ohmic resistance of IP-SOFCs

In the present work, the ohmic resistance of an integrated planar-SOFC (IP-SOFC) has been evaluated by developing a model whose equations have been solved numerically through an FEM method. The model allows to estimate the distribution of voltage and current density in the cell. A comparison between simulated and experimental data of area specific resistance is reported, which shows satisfactory agreement. The mathematical model has also been used to carry out some parametric studies for optimisation purposes. Indeed, a reduction in cell pitch length and an increase in electrode thickness are predicted to lead to a reduction in ohmic losses in IP-SOFCs.     

ΝΗ<Subscript>3</Subscript> decomposition in a proton conducting solid electrolyte cell

The reaction of NH₃ decomposition was studied on Ag in a proton conducting double chamber cell-reactor. The proton conductor was a strontia-ceria-ytterbia (SCY) perovskite of the form SrCe_0.95Yb_0.05O_3−α. The reaction was studied at 350–700 °C and atmospheric total pressure. The proton transference number (PTN) was calculated by simultaneous measurement of the imposed current and the proton flux and it was found to vary between 0.5 and 0.7. The effects of imposed current, temperature and inlet gas composition on the reaction rate and the PTN, were examined. Although the faradaic efficiency (Λ) remained near unity in all experiments, reaction rate enhancements (ρ) as high as 57 were achieved. An up to 90% decrease in the activation energy of the reaction was observed when protons were electrochemically “pumped” away from the catalyst.     

不锈钢冶炼过程中相关热力学问题的解析(Ⅰ)--原料预处理时的热力学问题

针对“电弧炉 多功能转炉 VOD”三步法不锈钢冶炼工艺，以脱磷为主线，从冶金热力学的角度对流程中涉及的几个重要工艺环节的可行性(包括电弧炉去硅保铬、铁水包同时脱磷脱硫等问题)进行了理论分析和计算。在此基础上，提出了强化冶炼和脱磷的工艺措施，从而为不锈钢冶炼全流程控制磷及优化脱磷工艺提供了理论依据。