Synthesis and application of phenylcarbamodithioate compound for steel protection

Phenyldithiocarbamate compound has been synthesized and studied as corrosion inhibitor for steel. Dithiocarbamate (DTC) compounds with linear alkyl groups are good inhibitors, but their stability is quite low in acidic solutions. It should be noted that long-term stability is important for practical applications, in order to avoid excess use of chemicals. So, we have synthesized phenyl substituted DTC which offers strong inhibition efficiency and extra stability. This new inhibitor is chemically adsorbed on steel through its DTC group, while the aromatic ring provides extra stability and long-term efficiency. For the assessment of corrosion kinetics, we have utilized potentiodynamic and ac impedance studies; also solution assay analysis was realized with atomic absorption spectroscopy. It was revealed that inhibitor exhibits remarkably high efficiency, even under elevated temperature conditions. At 55 °C temperature conditions, i_corr value decreased from 5050 to 154 μA cm^?2, with the addition of 500 ppm inhibitor. The long-term stability of inhibitor was also tested and 85.93% efficiency was obtained after three days of exposure period for 500 ppm concentration.     

Using the Schwinger inverse method for solutions of inverse transport problems in two-dimensional cylindrical geometries

The Schwinger method for solving inverse transport problems is applied to the problems of interface location identification, shield material identification, source isotope weight fraction identification, and material mass density identification (separately) in multilayered two-dimensional cylindrical gamma radiation source/shield systems. The method is iterative and estimates unknown interface locations, source isotope weight fractions, and material densities directly, while the unknown shield material is identified by estimating its total macroscopic gamma-ray cross sections. The energies of discrete gamma-ray lines emitted by the source are assumed to be known, while the unscattered flux of the lines is assumed to be measured at points external to the system. In numerical test cases, the Schwinger method correctly identifies the unknowns when the same deterministic ray-tracing code is used for both the parameter estimation process and simulation of the measured data. With realistic simulation of the measured data using a Monte Carlo code, the method produces more ambiguous results for interface location, shield material identification, and material density identification. The method works well for source weight fraction identification with measured data simulated by Monte Carlo. In addition to the application to more realistic (two-dimensional) problems, this paper extends previous work on the Schwinger inverse method by using surface formulas for unknown interface locations, automatic correction attempts for violated constraints, and ray-tracing instead of discrete-ordinates for transport calculations.     

Evaluation of Disturbance Weighting Parameter of Minimax Attenuation Problems

Abstract:   This article presents a simple evaluation of the disturbance weighting parameter of well-known minimax disturbance attenuation problems derived for earthquake-excited structures. It is concluded from a careful analysis of the derived closed form solutions that linear quadratic regulator (LQR) performance which corresponds to white noise assumption is the best performance of the sub-optimal minimax control (OMC) although it is also the worst performance of the OMC and the disturbance weighting parameter is as a measure of the system stability. For the completeness of the article, OMC is also compared to LQR and unimplementable optimal control.     

Modeling and simulation of 5-axis milling processes

5-axis milling is widely used in machining of complex surfaces. Part quality and productivity are extremely important due to the high cost of machine tools and parts involved. Process models can be used for the selection of proper process parameters. Although extensive research has been conducted on milling process modeling, very few are on 5-axis milling. This paper presents models for 5-axis milling process geometry, cutting force and stability. The application of the models in selection of important parameters is also demonstrated. A practical method, developed for the extraction of cutting geometry, is used in simulation of a complete 5-axis cycle.     

Electricity production from twelve monosaccharides using microbial fuel cells

Direct generation of electricity from monosaccharides of lignocellulosic biomass was examined using air cathode microbial fuel cells (MFCs). Electricity was generated from all carbon sources tested, including six hexoses (d-glucose, d-galactose, d(−)-levulose (fructose), l-fucose, l-rhamnose, and d-mannose), three pentoses (d-xylose, d(−)-arabinose, and d(−)-ribose), two uronic acids (d-galacturonic acid and d-glucuronic acid) and one aldonic acid (d-gluconic acid). The mixed bacterial culture, which was enriched using acetate as a carbon source, adapted well to all carbon sources tested, although the adaptation times varied from 1 to 70 h. The maximum power density obtained from these carbon sources ranged from 1240 ± 10 to 2770 ± 30 mW m⁻² at current density range of 0.76–1.18 mA cm⁻². d-Mannose resulted in the lowest maximum power density, whereas d-glucuronic acid generated the highest one. Coulombic efficiency ranged from 21 to 37%. For all carbon sources tested, the relationship between the maximum voltage output and the substrate concentration appeared to follow saturation kinetics at 120 Ω external resistance. The estimated maximum voltage output ranged between 0.26 and 0.44 V and half-saturation kinetic constants ranged from 111 to 725 mg L⁻¹. Chemical oxygen demand (COD) removal was over 80% for all carbon sources tested. Results from this study indicated that lignocellulosic biomass-derived monosaccharides might be a suitable resource for electricity generation using MFC technology.     

A Simple Active Control Algorithm for Earthquake Excited Structures

Abstract: A simple integral type quadratic functional is proposed as the performance index so that the optimal control policy is derived based on the minimization of the proposed performance index between the successive control instants by using the method of calculus of variations. The resulting optimal control law is applied to seismically excited linear buildings modeled as lumped mass shear frame structures. Active tendon actuators are considered as control devices. The performance of the proposed control (PC) is investigated when the example structure is subjected to three different seismic inputs and compared to the uncontrolled case and the classical linear optimal control (CLOC), which requires the solution of nonlinear matrix Riccati equation. It is shown by numerical simulation results that the PC is capable of suppressing the uncontrolled seismic vibrations of the linear structures and performs better than the CLOC.     

Generation of electricity in microbial fuel cells at sub-ambient temperatures

Direct generation of electricity from a mixture of carbon sources was examined using single chamber mediator-less air cathode microbial fuel cells (MFCs) at sub-ambient temperatures. Electricity was directly generated from a carbon source mixture of d-glucose, d-galactose, d-xylose, d-glucuronic acid and sodium acetate at 30 °C and <20 °C (down to 4 °C). Anodic biofilms enriched at different temperatures using carbon source mixtures were examined using epi-fluorescent, scanning electron microscopy, and cyclic voltammetry for electrochemical evaluation. The maximum power density obtained at different temperatures ranged from 486 ± 68 mW m⁻² to 602 ± 38 mW m⁻² at current density range of 0.31 mA cm⁻² to 0.41 mA cm⁻² (14 °C and 30 °C, respectively). Coulombic efficiency increased with decreasing temperature, and ranged from 24 ± 3 to 38 ± 1% (20 °C and 4 °C, respectively). Chemical oxygen demand (COD) removal was over 68% for all carbon sources tested. Our results demonstrate adaptation, by gradual increase of cold-stress, to electricity production in MFCs at sub-ambient temperatures.     

An improved gray line profile method to inspect the warp–weft density of fabrics

Image processing has become a tremendous tool for various fields of applications as well as for textile manufacturing industry in recent years. Inspection of fabric density is one of the major issues for fabric manufacturers in textile industries. In this study, an image processing method comprising of linear and nonlinear techniques for automatic inspection of warp and weft yarn density of fabrics has been proposed. By avoiding common problems of linear filtering such as blurring and localization, anisotropic diffusion filtering has been applied as preprocessing operation to enhance the edge region/boundaries between adjacent yarns of the fabric images. We conjecture that given a skewed gray level image, the number of peaks in the gray line profile of the image is minimized if the image is rotated in such a way that the inter-spaces between yarns are aligned with the vertical axis. Gabor filter, an orientation-sensitive filter, is applied to the skewed image at that angle to boost the edges between inter-spaces. The number of warp and weft yarn density has been inspected by applying gray line profile method. Simulations have been done on a wide range of fabric image data set. The results have shown that nonlinear and steered filters made a contribution to the performance of the method. The number warp and weft yarn densities are determined with an accuracy rates above 90%.