Electrical power generation from piezoelectric electrospun nanofibers membranes: electrospinning parameters optimization and effect of membranes thickness on output electrical voltage

Nanogenerators based on piezoelectric nanofibers capable to scavenging mechanical energy from the environment and converting into usable electrical energy. In this research work, the electrospinning parameters were optimized to produce randomly oriented uniform PVDF nanofiber mats without structural defects. Then, optimized nanofiber membranes with different thickness (110, 220, and 310 μm) were fabricated and their output voltages as a performance factor of the nanogenerator were measured. Results indicated that the nanogenerator based on piezoelectric nanofibers can generate voltage as high as several volts electrical outputs by applying mechanical impact. Finally, to investigate the effect of pure thickness on power harvesting efficiency, output voltages of samples were normalized to thickness. Results showed that in spite of the existed literature, increases in nanofiber membrane’s thickness can lead to decrease the output voltage of nanogenerator. These results imply promising applications for various wearable self-powered electrical devices within the clothing systems.     

Tribocorrosion Behavior of Aluminum/Alumina Composite Manufactured by Anodizing and ARB Processes

In the present work, tribocorrosion behavior of Al/Al₂O₃ composite strips manufactured by anodizing and accumulative roll bonding (ARB) processes was investigated. The alumina quantity was 0.48, 1.13, and 3.55 vol.% in the aluminum matrix. Tribocorrosion experiments were conducted using a ball-on-plate tribometer, where the sliding contact was fully immersed in 1 wt.% NaCl solution. The composite sample served as a working electrode and its open circuit potential (OCP) was monitored before, during, and after sliding. In order to characterize the electrochemical behavior of the surface before and after sliding electrochemical impedance spectroscopy (EIS) was used and wear was also measured. Furthermore, the influence of quantity and distribution of reinforcement particles in the matrix on OCP and EIS was evaluated. It was found that the quantity, shape, size, and dispersion of alumina particles in the aluminum matrix strongly affected the measured tribocorrosion characteristics. The results showed that inhomogeneous, lower quantity, fine, and acicular-shape alumina particles cause serious materials loss in tribocorrosion process.     

Effect of friction,annealing conditions and hardness on the bond strength of Al/Al strips produced by cold roll bonding process

Layered materials have become an increasingly interesting topic in industrial development. Cold roll bonding (CRB) process, as a solid phase method of bonding same or different metals by rolling at room temperature, has been widely used in manufacturing process. In this paper, characteristics such as bond strength and threshold deformation of as-received commercial pure aluminum (AA1100) strips prepared by the cold roll bonding process are investigated. Bond strength is evaluated by the peeling test. The main factors evaluated included effects of different annealing time, annealing temperature, hardness, and the effect of friction coefficient on bond strength. It is found that bond strength is enhanced by increasing annealing time, friction coefficient, and annealing temperature but that it is inversely proportional to hardness.     

An improved wavelet-based speech enhancement by using speech signal features

This paper presents a new speech enhancement system that works in wavelet domain. The core of system is an improved WaveShrink module. First, different parameters of WaveShrink are studied; then, based on the features of speech signal, an improved wavelet-based speech enhancement system is proposed. The system uses a novel thresholding algorithm, and introduces a new method for threshold selection. Moreover, the efficiency of system has been increased by selecting more suitable parameters for voiced, unvoiced and silence regions, separately. The proposed system has been evaluated on different sentences under various noise conditions. The results show a plausible improvement in performance of system, in comparison with similar approaches.     

TBM performance estimation using a classification and regression tree (CART) technique

Bulletin of Engineering Geology and the Environment - With widespread increasing applications of mechanized tunneling in almost all ground conditions, prediction of tunnel boring machine (TBM)...     

Analytical investigation on performance of special moment‐resisting connections with unequal beam depths

This study considers the effect of detailing of an interior beam to column connection with unequal beam depths on seismic performance of special moment‐resisting frame (SMRF), which has not explicitly been taken into account, despite its possible occurrence in engineering practice, by the current codes and provisions. Studied detailing consists of a continuity plate arrangement, cover plate, flange plate and haunch connection system as alternatives in order to connect a shallow beam and a deep beam to column. To improve the understanding of seismic performance in SMRF connections, coordinated analytical and experimental studies have been conducted to examine the effect of different geometries and the mentioned alternatives on the seismic performance of SMRF with unequal beam depths. This work describes the analytical studies and includes a summary of the experimental results used in the development and validation of the analytical models; the experiment and analyses show that some detailing could provide ductile behavior with a total storey drift angle of 0.06 rad before experiencing 20% strength degradation while other detailing would not satisfy this criterion. Copyright © 2015 John Wiley & Sons, Ltd.     

Surfactant cleaning of ultrafiltration membranes fouled by whey

A polyethersulphone ultrafiltration membrane was prepared for concentration of whey. The membrane was fouled by whey and the effect of different cleaning agents on flux recovery of the fouled membrane was studied. The optimum cleaning procedure for membrane regeneration was elucidated. The results showed that a combination of surfactants (anionic, cationic and nonionic) may be employed as the optimum cleaning agent for maximum flux recovery. The fluorescence studies revealed that the cationic surfactant interact with proteins by breaking the intra‐chain hydrophobic bonding and providing electrostatic repulsion. Changing the alkyl chain from dodecyl to hexadecyl increases the interaction of surfactant–protein. Dodecyltrimethylammonium bromide (DTAB) provided a weak interaction with whey proteins than to tetradecyltrimethylammonium bromide (TTAB) and cetyltrimethylammonium bromide (CTAB). All data obtained in this study support a surfactant–protein interaction in which hydrophobic forces play a dominant role. The nonionic surfactants poly(oxyethylene) isooctyl phenyl ether (TX‐100) and anionic surfactants SDS interact with amino acids in the inner protein structure thus denaturate tertiary protein structure and reduce hydrophobic interaction of proteins by membrane surface.     

Electromagnetic Spectrum Contribution in Astronomy,Health, Atmospheric,Geology and Environment Applications

International Journal of Wireless Information Networks - Spectrum technologies are shaping the way our world connects, communicates, and functions. Radio nodes connect through a nearly ubiquitous...     

A clustering-based short-term load forecasting using independent component analysis and multi-scale decomposition transform

The Journal of Supercomputing - A short-term electrical load forecasting model is proposed in this work. The proposed model is based on independent component analysis (ICA), discrete wavelet...