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This paper aims to report an experimental investigation of the galvanic corrosion that occurs between the base metal and the welds in X52 carbon steel petroleum pipelines when exposed in carbon dioxide (CO₂)-containing saltwater at pH 4 at room temperature. The pipeline was fabricated by electric resistance welding (ERW).

The experimental setup was a closed glass cell equipped with a silver/silver chloride (Ag/AgCl) reference electrode, two working electrodes (the weld metal and the parent steel specimens) and a gas bubbler. The corrosion potential and polarization resistance of the base metal and the weld were determined using electrochemical testing methods: potentiodynamic polarization scans and linear polarization resistance measurement. The galvanic currents of the base metal when coupled to the weld metal were measured using zero resistance ammetry.

The weld metal was the anode of the couple for a very short time at the beginning of the experiment and then became the cathode until the end of the experiment. This indicates that electric resistance welded X52 steel pipe is a promising material to be operated in CO₂-containing saltwater at pH 4 and 25°C because the weld area is cathodic to the parent metal, the value of the galvanic current is very low (in the order of nanoamps) and the area of the anode (i.e. the parent metal) is significantly larger than that of the cathode (weld metal).

Further experimental research could be performed to investigate the galvanic corrosion behavior between the parent metal and the weld area of X52 carbon steel petroleum pipelines in CO₂-containing saltwater at different pH values, temperature and velocity.

Electric resistance welded X52 steel pipe is a promising material for use with CO₂-containing saltwater environments at pH 4 and 25°C.

The new information presented in the paper is the galvanic corrosion behavior between the parent metal and the ERW weld metal of X52 carbon steel in CO₂-containing solutions. The paper should be useful to researchers working in the field of oil industry corrosion.

The paper aims to report an experimental investigation of the effectiveness of an alkyl amine‐based inhibitor on the corrosion behavior of 1018 carbon steel in sea water. The adsorption equilibrium for this corrosion inhibitor on carbon steel was also investigated. The corrosion inhibitor was evaluated based on parameters such as inhibitor concentration, temperature, stirring speed and pH.

The experimental setup employed an autoclave with a flow circulation system. Weight loss determinations and electrochemical techniques such as polarization resistance and potentiodynamic polarization were used to detect and monitor the performance of the corrosion inhibitor. Surface examination of the steel substrate before and after applying different doses of inhibitor was undertaken using Fourier transform infrared spectroscopy (FT‐IR), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS).

Inhibition efficiency was enhanced by adsorption of amine‐containing functional groups on the steel surface. This adsorption capacity was measured and fitted Langmuir and Shawabkeh‐Tutunji isotherms and was found to require a maximum requirement of 1.08 mg of corrosion inhibitor to provide a monolayer of cover on the carbon steel surface. The inhibition efficiency increased with increasing the inhibitor concentration and solution pH. Moreover, increasing the solution temperature and stirring speed had an adverse effect on inhibition efficiency. Polarization data fitted by the Butler‐Volmer Equation showed the values of anodic and cathodic Tafel coefficients were an average of 0.8 and 0.2, respectively. The measured corrosion rates decreased rapidly within the first hour after commencing the experiments, which is related to the formation of a protective oxide film.

More inhibitor concentrations can be studied in order to draw more comprehensive conclusions on the efficiency of the tested inhibitor.

The effect of alkyl amine‐based inhibitor on the corrosion inhibition characteristic of 1018 carbon steel (CS) in sea water was determined at different inhibitor concentrations, temperatures, stirring speeds and pH.

The new information reported in this paper is the effect of alkyl amine‐based inhibitor on the corrosion characteristics of 1018 carbon steel in seawater using an autoclave with a flow circulation system. The paper is valuable to researchers in the area of corrosion inhibitors and oil and gas industry.

As a good absorbing material candidate, a functionally graded wave absorber can be tailored to satisfy the impedance match principle by gradually changing material property. The paper aims to discuss these issues.

The electromagnetic wave absorption properties are discussed. An analysis model is proposed to provide an insight into its mechanical characteristics during wave absorption. Considering the energy-converting and thermal deformation properties, the thermoelastic behaviors of an absorber are analyzed by numerical method. The effects of material and geometrical properties are discussed in detail.

The results demonstrate that absorbing effect of graded composite is enhanced. Good performance of low reflectance and high absorption with gentle thermal stress distribution can be obtained by proper designing of the gradient absorber.

Functionally graded materials exhibit a progressive compositional gradient change along certain dimension of structures, which can be used as absorbing materials for the gradual change of material property tailored to satisfy the principle of impedance match. The design of functionally graded absorbing materials usually should consider not only the electromagnetic performance, but also the mechanical properties simultaneously. Therefore, few investigations have addressed the mechanical characteristics of absorbers. This paper presents some studies on the electromagnetic, especially mechanical behaviors during electromagnetic wave absorption. It is helpful to provide mechanical reference for designing an absorber.

Non-orthogonal multiple access (NOMA) is a much hopeful scheme, which is deployed to enhance the spectral efficiency (SE) significantly, and it also enhances the massive access that has attained substantial concern from industrial and academic domains. However, the deployment of superposition coding (SC) at the receiver side resulted in interference. For reducing this interference, “multi-antenna NOMA” seems to be an emerging solution. Particularly, by using the channel state information at the transmitter, spatial beam forming could be deployed that eliminates the interference in an effective manner.

This survey analyzes the literature review and diverse techniques regarding the NOMA-based spatial modulation (SM) environment. It reviews a bunch of research papers and states a significant analysis. Initially, the analysis depicts various transmit antenna selection techniques that are contributed in different papers. This survey offers a comprehensive study regarding the chronological review and performance achievements in each contribution. The analytical review also concerns on the amplitude phase modulation (APM) selection schemes adopted in several contributions. Moreover, the objective functions adopted in the reviewed works are also analyzed. Finally, the survey extends with various research issues and its gaps that can be useful for the researchers to promote improved future works on NOMA-based SM.

This paper contributes to a review related to NOMA-based SM systems. Various techniques and performance measures adopted in each paper are analyzed and described in this survey. More particularly, the selection of transmission antenna and APM are also examined in this review work. Moreover, the defined objective function of each paper is also observed and made a chronological review as well. Finally, the research challenges along with the gaps on NOMA-based SM systems are also elaborated.

This paper presents a brief analysis of NOMA-based SM systems. To the best of the authors’ knowledge, this is the first work that uses NOMA-based SM systems to enhance SE.

The purpose of this study is to investigate the impact of COVID-19 on some fiscal and monetary indicators in the Kingdom of Saudi Arabia.

The research relied on data, studies and reports issued by the International Monetary Fund, Arab Monetary Fund, Saudi Central Bank, Investing Website and the World in Data Website.

Many sectors have been affected by the COVID-19 pandemic, which outbreak has been associated with a high cost, in addition to increased inflation and prices, a result that was confirmed by the increase in consumer price indices for different sectors. The general consumer price index for the second period rose above that of the first period, while an upward shift occurred in the curve depicting the Saudi Riyal exchange rate against the United States (US) dollar during the second period above that of the first period, only in slope, due to outbreak of the pandemic. Impact of the number of daily new cases infected with COVID-19 was the highest on the opening and closing price indices of the food retail sector, the pharmaceutical sector and the transportation sector; while impact of the number of daily deaths by COVID-19 was the highest on the opening and closing price indices of the banking sector, the general index and the investment and finance sector. In addition, impact of the daily reproduction rate of COVID-19 was the highest on the opening price indices of the energy sector, the food production sector and the transportation sector.

The research aims to demonstrate measures taken by the Kingdom of Saudi Arabia through fiscal and monetary policies.

The COVID-19 pandemic is still an ongoing global pandemic. The virus was first identified in Wuhan City in China at the beginning of December 2019. At the end of January 2020, the World Health Organization (WHO) declared that the outbreak of the virus represented a public health emergency, and later, on March 11, 2020, WHO declared the situation had transformed into a pandemic. Until January 17, 2022, the pandemic had caused more than 328 million cases and 545 million deaths, while 188 million of the cases had recovered. It is worth mentioning that the pandemic caused several social and economic disruptions, including a global economic recession; shortages in goods, supplies and equipment due to consumers' panic and thus tendency to buy; besides causing other disruptions like the negative impacts on health, as well as political, cultural, religious and sport events that influenced economic policies, including both the fiscal and monetary policies of world countries (Wikipedia, 2022).

Social implications steps that taken to reduce the impacts of the COVID-19 pandemic, in addition to measuring the impacts of the COVID-19 pandemic (as the main event next to which other events fade up) on some of the fiscal and monetary indicators for the Kingdom of Saudi Arabia.

The research aims to demonstrate measures taken by the Kingdom of Saudi Arabia through fiscal and monetary policies to mitigate the impacts of the COVID-19 pandemic, in addition to measuring the impacts of the COVID-19 pandemic (as the main event next to which other events fade up) on some of the fiscal and monetary indicators for the Kingdom of Saudi Arabia.

The purpose of this paper was to investigate the corrosion behavior of X65 steel in the CO₂/oil/water environment using mass loss method, potentiodynamic polarization technique and characterization of the corroded surface techniques.

The weight loss analysis, electrochemical study and surface investigation were carried out on X65 steel that had been immersed in the CO₂/oil/water corrosive medium to understand the corrosion behavior of gathering pipeline steel. The weight loss tests were carried out in a 3L autoclave, and effects of flow velocity, CO₂ partial pressure and water cut on the CO₂ corrosion rate of X65 steel were studied. Electrochemical studies were carried out in a three-electrode electrochemical cell with the test temperature of 60°C and CO₂ partial pressure of 1 atm by recording open circuit potential/time and potentiodynamic polarization characteristics. The surface and cross-sectional morphologies of corrosion product scales were characterized using scanning electron microscopy. The phases of corrosion product scales were investigated using X-ray diffraction.

The results showed that corrosion rates of X65 steel both increased at first and then decreased with the increase of flow velocity and CO₂ partial pressure, and there were critical velocity and critical pressure in the simulated corrosive environment, below the critical value, the corrosion products formed on the steel surface were loose, porous and unstable, higher than the critical value, the corrosion product ?lms were dense, strong adhesion, and had a certain protective effect. Meanwhile, when the flow velocity exceeded the critical value, oil film could be adsorbed on the steel surface more evenly, corrosion reaction active points were reduced and the steel matrix was protected from being corroded and crude oil played a role of inhibitor, thus it influenced the corrosion rate. Above the critical CO₂ partial pressure, the solubility of CO₂ in crude oil increased, the viscosity of crude oil decreased and its fluidity became better, so that the probability of oil film adsorption increased, these factors led to the corrosion inhibition of X65 steel reinforced. The corrosion characteristics of gathering pipeline steel in the corrosive environment containing CO₂ would change due to the presence of crude oil.

The results can be helpful in selecting the suitable corrosion inhibitors and targeted anti-corrosion measures for CO₂/oil/water corrosive environment.

The purpose of this study is to explore the corrosion behaviors of tube pile steel with the addition of 0.2 per cent Cu and 0.2 per cent Cu-0.2 per cent Cr in half-immersion environment.

The electrochemical corrosion behaviors of tube pile steel with different alloy-elements addition were identified using the polarization curve method and electrochemical impedance spectroscopy technique. Corrosion product and its morphology were analyzed by X-ray diffraction, optical microscope and scanning electron microscopy.

Results indicate that the most serious corrosion occurred in the liquid-air interface zone due to the higher oxygen and water concentration. With the addition of Cu and Cu-Cr, pits were getting smaller and denser, transforming the corrosion type from pitting corrosion to uniform corrosion gradually. Rust layer containing Cu/Cr tended to compact and inhibited the anodic process, while the enrichment of Cu/Cr in rust layer decelerated the dissolution of substrate, thus the expanding of pits was suppressed.

This paper studied the corrosion behaviors of liquid-air interface zone of tube pile steel and verified the transformation of corrosion type with adding Cu, Cu/Cr elements.

This paper aims to analyze a failure case of a P110 tube in a CO₂ flooding well.

The chemical composition, microstructure and mechanical properties of the failed P110 tubing steel were tested, and met the API Spec 5CT standard. The fractures were investigated by scanning electron microscopy and energy dispersive spectroscopy.

Fracture was induced by stress corrosion cracking (SCC) and that the stress concentration caused by the mechanical damage played an important role in the failure. The failure case is a SCC failure affected by mechanical damage and galvanic corrosion.

The effect of the infiltration of groundwater was studied in the failure case. The stress concentration caused by the mechanical damage played an important role in the failure.

Oil-water two-phase flow is the most prevalent medium in oil field gathering pipelines, and the corrosion of pipelines is often highly localized. Therefore, the purpose of this paper is to investigate the corrosion behavior of 20# pipeline steel in the oil-water stratified liquids, vary the water content of the upper emulsion and study the difference of the corrosion process.

Combine the wire beam electrodes (WBE) technique and the corrosion weight loss method to investigate the corrosion behavior of 20# steel in produced water simulation fluid and oil-water stratified liquids, and a corrosion mechanism model was established for analysis and explanation.

The results of mass loss experiments showed that the average corrosion rate increased with the increase in the water content of the upper emulsion. The corrosion current distribution maps indicated that the most serious corrosion occurred in the produced water simulation liquid, and the corrosion process showed the law of waterline corrosion. In addition, it was also found that the corrosion of the WBE in the stratified liquids had obvious non-uniformities. The electrode wires at the oil-water interface suffered from severe corrosion, caused by the dissolution of crude oil acids in water and the uneven distribution of oxygen in the corrosive medium.

The WBE technique provides a deep insight into the corrosion phenomena at the oil-water interface, which is helpful for characterization of the non-uniformity of corrosion parameters and evaluating the risks of multiphase corrosive media.