Biogeography based hybrid scheme for automatic detection of epileptic seizures from EEG signatures

Biogeography Based Optimization (BBO) algorithm is one of the nature-inspired optimization methods, based on the study of geographical distribution of species on earth. The present research work is based upon decomposition of human electroencephalograms (EEG) signal by Wavelet Packet Transform, computation of a complete feature set using statistical and non-statistical properties followed by optimal selection of features by BBO; the optimality criterion being classification rate. The stopping criterion for BBO is set to 100% correct classification rate. The proposed algorithm is novel in terms of TWSVM computing the Habitat Suitability Index (HSI) values for BBO, perfect classification rate, low computation time, and feature selection mechanism. The proposed scheme outperforms several previous results reported in literature in that it gives a feature subset which gives 100% classification accuracy for different classification instances.     

Multi-scale wavelet transform filtering of non-uniform pavement surface image background for automated pavement distress identification

Non-uniform background of pavement images results in difficulties when segmenting pavement images for pavement distress identification. A novel and fast non-uniform background removal algorithm based on multi-scale wavelet transform is presented. The algorithm uses multi-scale wavelet transform to decompose pavement image and then reconstructs image background using low-wavenumber components through inverse wavelet transform. Brightness of image background is then corrected to achieve uniform background pavement image. The multi-scale wavelet transform algorithm is compared with median filter algorithm and morphological closing algorithm. Experimental results show that the proposed algorithm possesses the advantage of extracting tiny cracks more effectively than the other two algorithms, demonstrating its suitability to be used in automated pavement distress segmentation and identification.     

Polyaniline sensitized Pt@TiO2 for visible-light-driven H2 generation

Polyaniline is a typical conducting polymer with high migration electron rate, good stability, eco-friendly properties, and high absorption coefficients for visible light. In the present study, polyaniline decorated Pt@TiO₂ for visible light-driven H₂ generation is reported for the first time. The above-mentioned nanocomposite is prepared through a simple oxidative-polymerization and characterized by infrared spectroscopy, transmission electron microscopy, X–ray diffraction, thermogravimetric analysis, and ultraviolet–visible diffuse reflectance spectra. Polyaniline modification improves the absorption of the nanocomposite in visible light region via a photosensitization effect similar to dye–sensitization but does not influence the crystal structure and size of Pt@TiO₂. The polyaniline modified Pt@TiO₂ exhibits a remarkable visible light activity (61.8 μmol h⁻¹ g⁻¹) and good stability for H₂ generation (with an average apparent quantum yield of 10.1%) with thioglycolic acid as an electron donor. This work provides new insights into using conducting polymers, including polyaniline, as a sensitizer to modify Pt@TiO₂ for visible-light hydrogen generation.     

水热法主要提取因素对光皮木瓜多糖结构的影响

目的 优化水热法提取光皮木瓜（Chaenomeles sinensis）多糖的提取工艺条件，对光皮木瓜不溶性多糖的组成和结构进行分析。方法 预处理后的光皮木瓜样品经水热法提取、抽滤、冲洗，浓缩等操作，分别得到不溶性多糖、醇沉多糖和醇溶多糖，通过傅里叶变换红外光谱、扫描电子显微镜及X射线衍射分析不溶性多糖的组成和结构。 结果 多糖提取的较优条件为150 ℃/45 min，料液比1∶10 (W/V)；温度对水热法提取效果影响显著，适当升高温度、延长提取时间和减少料液比有利于多糖提取；高温虽能促进半纤维素溶解，但无法使木质素和木聚糖降解；即使提取温度不同，光皮木不溶性多糖的结构差异也极小；水热法提取光皮木瓜多糖不会导致多糖的功能性基团变化，只改变多糖的化学组成。结论 该研究可为光皮木瓜多糖的结构与功能研究提供实验依据，也为陕西白河光皮木瓜资源的综合利用提供研究参考。     

On the dynamical thermoelasticity problem for a hollow funtionally graded cylinder

A thermoelasticity problem of a pressurized infinite cylinder made of functionally graded material is solved analytically where material properties vary with radial position. Time dependent thermal and mechanical boundary conditions are assumed to act on the inner and outer surfaces of the cylinder. For thermal boundary conditions, temperature is prescribed on both surfaces, whereas for mechanical boundary conditions, tractions are prescribed on the boundaries. Obtaining distribution of temperature throughout the cylinder, the dynamical structural problem is solved and closed form relations are extracted for distributions of stress components.     

Texture image retrieval using adaptive tetrolet transforms

This paper proposes a novel technique for texture image retrieval based on tetrolet transforms. Tetrolets provide fine texture information due to its different way of analysis. Tetrominoes are applied at each decomposition level of an image and best combination of tetrominoes is selected, which better shows the geometry of an image at each level. All three high pass components of the decomposed image at each level are used as input values for feature extraction. A feature vector is created by taking standard deviation in combination with energy at each subband. Retrieval performance in terms of accuracy is tested on group of texture images taken from benchmark databases: Brodatz and VisTex. Experimental results indicate that the proposed method achieves 78.80% retrieval accuracy on group of texture images D1 (taken from Brodatz), 84.41% on group D2 (taken from VisTex) and 77.41% on rotated texture image group D3 (rotated images from Brodatz).     

Mild synthesis of benzylated bamboo in LiCl/DMSO solution

Benzylated bamboo was mildly synthesized in nonaqueous medium without mercerization pretreatment. The ball-milled bamboo was firstly preswelled in lithium chloride/dimethyl sulfoxide (LiCl/DMSO) solution and then reacted with benzyl chloride in the presence of solid NaOH with varying molar ratios of benzyl chloride to OH groups of bamboo (1–4), reaction times (1–8 h), and temperatures (60–90°C). Benzylated bamboo products with yields from 51.1 to 106.9% and with degrees of substitution [DS, apparent value evaluated by Fourier transform infrared (FTIR) spectra] between 0.2 and 1.2 were synthesized. FTIR and ¹³C cross polarization/magic angle spinning nuclear magnetic resonance (CP/MAS NMR) spectroscopy confirmed the incorporation of benzyl groups into bamboo; SEM observations of the highly benzylated bamboo showed porous surface with small irregular slices ascribed to the disruption of intermolecular and intramolecular hydrogen bonds between cellulose. Because of the degradation of amorphous components, the crystallinity decreased negligibly after modification and the thermal stability increased slightly but was lower than that of cellulose. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Development of Motor Model of Rotor Slot Harmonics for Speed Sensorless Control of Induction Motor

This paper proposes a novel mathematical dynamic model to represent the steady‐state and transient‐state characteristics of rotor slot harmonics of an induction motor for sensorless control. Although it is well known that the rotor slot harmonics originate from the mechanical structure of the induction motor, a mathematical model that describes the relationship between the stator/rotor currents of the induction motor and the slot harmonics has not yet been proposed. Therefore, in this paper, a three‐phase model of the induction motor that depicts the rotor slot harmonics is developed by taking into consideration the magnetomotive force harmonics and the change in the magnetic air gap caused by the rotor slots. The validity of the proposed model is verified by comparing the experimental results and the calculated values. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(3): 63–74, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22478     

Application of soft-thresholding on the decomposed Lamb wave signals for damage detection of plate-like structures

Effective application of the Lamb waves for structural health monitoring and damage identification intensively relies on the accurate damage-related feature extraction in the received signals. Most of existing signal processing methods extract the damage-related features from the time–frequency joint spectrum which requires a quite amount of effort. In this paper, the soft-thresholding process, based on different signal decomposition methods, is introduced to damage identification so that the damage-related signal features can be manifested more distinctively. By applying two popular signal decomposition methods (i.e., the discrete wavelet transform (DWT) and the empirical mode decomposition (EMD)), the signal of interest can be represented by a series of components with different frequencies. Since most noises exist in the high frequency range, it is feasible to alleviate noise by restricting the energy of high-frequency components. Finally, a denoised signal is synthesized using the corresponding reconstruction method. As an application, the soft-thresholding process is performed to detect a small crack on an isotropic aluminum plate under the white Gaussian noise contamination. The results, from both the numerical finite element simulation and experimental test, indicate that the soft-thresholding process is capable of effectively reducing the effect of noise, convincingly improving the sensitivity of damage identification, and discriminating relatively small damage.     

Image‐based Continuous Displacement Measurements Using an Improved Spectral Approach

Digital Image Correlation algorithms capable of determining continuous displacement fields are receiving growing attention in the field of mechanical properties identification. In this paper, we develop an Improved Spectral Approach (ISA) to reconstruct continuous displacements based on their Fourier decomposition. This approach leads to a time and memory‐efficient algorithm, thanks to the fast Fourier transform. Moreover, the Fourier‐based decomposition enables accurate heterogeneous measurements. Improvements consist in increasing the accuracy and convergence rate as well as dealing with non‐periodic displacements and images. Furthermore, a theoretical framework is presented to quantify the noise sensitivity of the ISA from which useful information is retrieved. The approach is evaluated using synthetic images deformed by heterogeneous displacement fields. Comparisons show that the introduced modifications lead to lower uncertainties by one order of magnitude in the case of non‐periodic images and displacement field studied. Moreover, first‐order (SO1) and second‐order (SO2) subset‐based Digital Image Correlation algorithms are compared with the ISA. The comparisons herein reveal that the uncertainties of the ISA are 6–9 times smaller than those of the SO1 due to insufficiency of the first‐order shape function for the estimation of heterogeneous displacements, while being slightly smaller than those of the SO2. Moreover, as the image smoothness decreases, the uncertainties of the SO2 deviate from those of the ISA and the exact displacements. The presented approach shows great potentials for challenging applications such as strain measurements at microstructural levels.