Bi-objective optimization approaches to many-to-many hub location routing with distance balancing and hard time window

Neural Computing and Applications - This study addresses a many-to-many hub location-routing problem where the best-found locations of hubs and the best-found tours for each hub are determined with...     

A study on the mechanical strength of Fe2O3/Cr2O3/CuO catalyst for high temperature water gas shift reaction

Journal of Porous Materials - The present study aims to investigate the effects of iron (hydr)oxide phases formed during precipitation and the addition of different binders on the mechanical and...     

Binary nanocomposite of Fe3O4/MWCNTs for adsorption of Reactive Violet 2: Taguchi design,kinetics and equilibrium isotherms

Binary nanocomposite of magnetite/multi-walled carbon nanotubes (Fe₃O₄/MWCNTs) was synthesized through the chemical reduction method at room temperature and employed for adsorptive removal of Reactive Violet 2 (RV2) from aqueous solutions. The experiments were carried out based on a Taguchi experimental design with four variables of the adsorbent dosage, pH, contact time and ionic strength. Analysis of variance (ANOVA) showed that the adsorbent dosage with contribution of 79.14% was the most effective factor on the process efficiency. Percent contributions of solution pH and contact time were found to be 9.85 and 6.16, respectively. The ionic strength showed no considerable contribution to the response. The optimal dye removal conditions were determined as the adsorbent dosage of 2.0?g?L^?1, pH = 6, contact time of 30?minutes and ionic strength of 0.1?mol?L^?1 which resulted in the average efficiency of 98.23% for RV2 removal. The results showed that RV2 adsorption onto Fe₃O₄/MWCNTs followed the pseudo-second order kinetic model. Moreover, the intraparticle diffusion model suggested a two-step adsorption process, including macropore diffusion of about 94% of RV2 molecules into the nanocomposite surface during ～10?minutes and a micropore diffusion as the rate-limiting step. Fitting of the experimental data to six isotherms (Langmuir, Harkins-Jura, Freundlich, Tempkin, Halsey and Redlich-Peterson) was also investigated and Redlich-Peterson and Halsey isotherms provided the best quality of fitting for the dye-nanocomposite system with R² values of 0.9992 and 0.9906, respectively.     

Application of Dispersive Liquid–Liquid Micro-extraction Using Mean Centering of Ratio Spectra Method for Trace Determination of Mercury in Food and Environmental Samples

In the present study, dispersive liquid–liquid micro-extraction has been applied for trace extraction and determination of mercury (Hg) ions in environmental samples. The mean centering of ratio spectra method was used to optimize the experimental parameters affecting the extraction of Hg. The factors influencing the extraction procedure such as type and volume of extracting and disperser solvent, concentration of chelating reagent, pH, salt effect, and centrifuge time were investigated and optimized. Under the optimized conditions, the limit of detection of the method was 0.15 μg l^?1 and enrichment factor was 39. The calibration curve was linear in the range of 0.5–100 μg l^?1 with a correlation of determination (R ²) of 0.998. The relative standard deviation for determination of 40 μg l^?1 of Hg(II) was 2.6 % (n?=?5). The proposed method was applied for the determination of Hg in pine leaf, sea and river fish, sand, and water samples as indicators of environmental pollution and cigarette with satisfactory analytical results. In comparison with other methods, the proposed method is very simple, easy, rapid, and sensitive for determination of Hg at trace levels in complex matrices.     

An equivalent electrical circuit design for pipeline corrosion monitoring based on piezoelectric elements

Underground pipelines are important infrastructure for transporting energy resources, particularly water and oil. Due to the high risk of damage and possible consequences, close monitoring of pipelines is a serious challenge for researchers and decision makers. Piezoelectric sensors/actuators are being used to monitor the physical characteristics of pipelines, including corrosion and crack. Piezoelectric ceramics as transmitters and/or receivers are connected to data concentrators in order to monitor the defects in pipelines. The performance and accuracy of this system highly depends on the accurate interpretation of the received electrical signals due to changing mechanical fields. However, due to the existence of two different fields, namely, electrical and mechanical, in this problem, simulation and interpretation of the damages occurring in pipelines is a consistent challenge. This paper proposes an equivalent electrical circuit model for a complete monitoring system which contains piezoelectric ceramics and a pipeline equivalent electrical circuit with corrosion defects and cracks through the pipeline. The pipeline is integrated with PZT sensor and actuator, in which PZT actuator generates waves along the thickness of the pipeline and its response is received by a PZT sensor. The proposed model approximates the electrical signal achieved by the PZT sensor to a complete health monitoring system. As the sensing signals in the present model are in one single field (i.e. electrical instead of mechanical and electrical), analysis and signal processing are more efficient, and the results are better understood. Numerical examples and, where applicable, simple tests have been presented to show the functionality and performance of the system.     

Voice activity detection based on using wavelet packet

This paper, presents a robust voice activity detection (VAD) technique based on wavelet packet. In this technique sub-bands and their amplitudes are represented as the vectors for each sample time in order to find a new feature from the frequency and amplitude changes. On the other hand, the multi-resolution analysis property of the wavelet packet transform (WPT), the voiced, unvoiced, and transient components of speech can be distinctly discriminated. Then, a new feature extraction method is implemented based on observations of the angles between vectors. This feature extraction method retains most unvoiced sounds in a voice active frame. Experimental results show that the proposed WT feature parameter can extract the speech activity under poor SNR conditions and that it is also insensitive to variable-level of noise.     

Comparison of pregabalin with doxepin in the management of uremic pruritus: a randomized single blind clinical trial

Introduction: Pruritus is one of the frustrating skin manifestations of advanced renal failure. Many options have been used for the management of uremic pruritus (UP) such as pregabalin. There are some studies that reported beneficial effects of pregabalin in reducing UP; however, most of them did not have a comparator arm. Therefore, we designed this study to compare antipruritic effects of pregabalin with doxepin in the management of pruritus in hemodialysis patients. Methods: Seventy‐two patients suffering from UP were randomly assigned to receive pregabalin (50 mg every other day) or doxepin (10 mg per day) for 4 weeks. Severity of pruritus and its effect on quality of life were assessed by visual analog scale (VAS), 5‐D itch scale and dermatology life quality index (DLQI) at baseline and after 1 week, 2 weeks and 4 weeks of the treatment. Findings: Mean scores of the VAS decreased from 7.5± 1.4 and 7.1 ± 1.3 at baseline to 2.1 ± 2.6 and 4.2 ± 2.6 at the end of the study (P < 0.001) in the pregabalin and doxepin groups, respectively. Similarly, pregabalin significantly reduced mean scores of the 5‐D itch scale and the DLQI compared to doxepin. The most reported side effect in each group was somnolence which occurred in similar rates in the both groups. Discussion: Pregabalin was more effective than doxepin in reducing the severity of uremic pruritus and improving the quality of life of patients in this study, so we suggest that clinician can consider pregabalin prior to using antihistamine drugs in the management of severe itch in hemodialysis patients.