Study of Adsorption/Desorption Effect of 2-Mercaptobenzothiazole as Sweet Corrosion Inhibitor on API-5L X60 Steel

Protection of Metals and Physical Chemistry of Surfaces - In this study, the inhibitive performance of 2-mercaptobenzothiazole (2MBT) and 2-aminobenzothiazole (2ABT) were investigated on API-5L X60...     

Development of broadband forward‐wave directional couplers loaded by periodic patterned ground structure

In this paper two wideband Forward‐Wave Directional Couplers (FWDCs) with 0 dB and 3 dB coupling level are proposed. Using periodic patterned ground structure in a microstrip coupled lines by a new unit cell; even‐ and odd‐mode characteristic impedances of the couplers are equal over a wide frequency range. Moreover, it provides a constant phase difference between even and odd‐modes. The proposed cell is modeled using the equivalent circuit model and a design procedure is introduced for designing FWDCs for an arbitrary value of coupling level. The introduced couplers are numerically investigated and a prototype of both couplers is made. It is shown that for 0 dB coupling level, the measured coupling is 0.85 dB with 1 dB flatness over fractional bandwidth of 96% bandwidth. In case of 3 dB coupling, the measured coupling level is 3.5 dB at 7.42 GHz with 1 dB flatness over fractional bandwidth of 67.1%.     

Optimization of CO<Subscript>2</Subscript> corrosion for API X70 steel on acetic acid contained environment

The corrosion behavior of X70 steel in a CO₂-containing solution was evaluated by using linear polarization resistance. The corrosive media was a deoxygenated 3% NaCl solution, saturated with CO₂ at different temperatures. The fluid flow over the steel surface was 2.5 m/s as a peripheral velocity of a rotating cylinder electrode (RCE). It is concluded that the specific micro-structure of X70 steel influences the corrosion behavior of the steel. The percentage contribution of different effective factors (acetic acid concentration, temperature and exposure time) has been discussed on corrosion rate of different samples.     

Integration of scientific and social networks

In this paper, we address the problem of scientific-social network integration to find a matching relationship between members of these networks (i.e. The DBLP publication network and the Twitter social network). This task is a crucial step toward building a multi environment expert finding system that has recently attracted much attention in Information Retrieval community. In this paper, the problem of social and scientific network integration is divided into two sub problems. The first problem concerns finding those profiles in one network, which presumably have a corresponding profile in the other network and the second problem concerns the name disambiguation to find true matching profiles among some candidate profiles for matching. Utilizing several name similarity patterns and contextual properties of these networks, we design a focused crawler to find high probable matching pairs, then the problem of name disambiguation is reduced to predict the label of each candidate pair as either true or false matching. Because the labels of these candidate pairs are not independent, state-of-the-art classification methods such as logistic regression and decision tree, which classify each instance separately, are unsuitable for this task. By defining matching dependency graph, we propose a joint label prediction model to determine the label of all candidate pairs simultaneously. Two main types of dependencies among candidate pairs are considered for designing the joint label prediction model which are quite intuitive and general. Using the discriminative approaches, we utilize various feature sets to train our proposed classifiers. An extensive set of experiments have been conducted on six test collection collected from the DBLP and the Twitter networks to show the effectiveness of the proposed joint label prediction model.     

2-Butyne-1,4-diol as a novel corrosion inhibitor for API X65 steel pipeline in carbonate/bicarbonate solution

The inhibition effects of 2-butyne-1,4-diol on the corrosion susceptibility of grade API 5L X65 steel pipeline in 2 M Na₂CO₃/1 M NaHCO₃ solution were studied by electrochemical techniques and weight loss measurements. The results indicated that this inhibitor was a mixed-type inhibitor, with a maximum percentage inhibition efficiency of approximately 92% in the presence of 5 mM inhibitor. Atomic force microscopy revealed that a protective film was formed on the surface of the inhibited sample. The adsorption of the inhibitor was found to conform to the Langmuir isotherm with the standard adsorption free energy of ?21.08 kJ mol^?1.     

Evaluation of a high resistance paint coating with EIS measurements: Effect of high AC perturbations

Electrochemical impedance spectroscopy (EIS) was used to evaluate a high resistance paint coating immersed in 10% sodium chloride solution. Although this method was valuable in evaluating this type of coating there were many fluctuations in measured data at low AC perturbations. In this work the role of high AC perturbation to fit EIS data of high resistance coating with equivalent electrical circuit (EEC) was studied. EIS measurements showed that these fluctuations could be reduced by high AC perturbation. The impedance plots showed best fitting at 400 mV AC perturbation at the initial time of immersion and at 100 mV AC perturbation after 90 days of immersion. The coating resistance and coating capacitance were extracted from the Bode and Nyquist plots during the period of 90 days of immersion.     

Crosstalk analysis of multi‐microstrip coupled lines using transmission line modeling

This article presents a new analytical method to predict crosstalk of a homogeneous terminated two microstrip coupled lines over a ground plane using transmission line theory. The derived formula is frequency and location dependent, which can be used to quickly estimate the crosstalk of a coupled line. Also, the effect of the geometrical parameters of the lines and load are included in the derived formula. Presented method can be used for the other types of coupled lines including lossy or lossless lines. To verify the accuracy of the introduced method, a few microstrip coupled line structures with different geometrical parameters are considered numerically and experimentally. The results of crosstalk based on the proposed analytical methods, simulation study using high frequency structure simulator and those obtained by measurements are reported and compared with each other. It is shown that our proposed method accurately estimates the amount of crosstalk for a two microstrip coupled lines.     

Crosstalk analysis of uniform and nonuniform lossy microstrip‐coupled transmission lines

In this article, an analytical method is presented to precisely estimate the crosstalk of uniform and nonuniform microstrip‐coupled transmission lines (TLs) in frequency domain using modified transmission matrix. The obtained expression is quantitatively related in terms of the geometrical parameters of the coupled lines. A straightforward procedure is presented to obtain a closed form formula to accurately determine the crosstalk of a microstrip‐coupled line. For a nonuniform structure, the TL is divided into a few series of uniform sections with a specific modified transmission matrix. The total modified transmission matrix is determined by multiplying the modified transmission matrix of different sections and then the crosstalk can be calculated using the total modified transmission matrix. Several structures are considered to confirm the validity of the presented method. It is shown that the obtained results are in a good agreement with those obtained by simulation and measurement.     

A probe into low-temperature stress corrosion cracking of 304L stainless steel by scanning vibrating electrode technique

Scanning vibrating electrode technique (SVET) that is a reliable method for local measuring of electrochemical potential at the sample surface is used to study stress corrosion cracking of 304L stainless steel in 0.1?M NaCl+HCl solution at room temperature. SVET maps showed a periodic emergence and receding as well as a forward mobility of an active anodic front. This behaviour could indicate a step-wise and discontinuous crack propagation mechanism. SEM images revealed the presence of a side crack adjacent to the main crack which confirms the presence of an expanded anodic front in SVET maps.     

Improvement in Dispersion of Phosphate Pigments Modified by Functionalized Graphite Nanoplatelets and Its Influence on Epoxy Coating Adhesion

Tripolyphosphate corrosion inhibitor was modified by functionalized graphite nanoplatelets to obtain a hybrid nanoparticle (functionalized graphite nanoplatelets–tripolyphosphate) with homogenous dispersion in epoxy coating. The effect of functionalized graphite nanoplatelets–tripolyphosphate dispersion on adhesion and anticorrosion behavior was discussed. Characterization analyses of the hybrid nanoparticle were performed by Fourier transform-infrared spectroscope, scanning electron microscope, and transmission electron microscope. Tripolyphosphate was linked to functionalized graphite nanoparticles by hydrogen bondings. Different epoxy coatings formulated with 1 wt% of functionalized graphite nanoplatelets, functionalized graphite nanoplatelets–tripolyphosphate, and tripolyphosphate were evaluated. Results showed, compared to traditional phosphate pigments, the adhesion of functionalized graphite nanoplatelets–tripolyphosphate epoxy coating and its anticorrosion behavior were significantly increased with the lowest loadings amounts.