This study innovatively investigates the effect of silica nanoparticles on crude oil pipeline flow drag reduction using computational fluid dynamics (CFD). Turbulent flow conditions were assumed for all simulations according to Reynolds number values. The results of the numerical simulations were validated against the experimental measurements, showing a maximum deviation of less than 8.6% in percentage drag reduction (DR%). The effect of some parameters such as fluid viscosity, flow velocity and pipe diameter (defined collectively by the Reynolds number) and pipe materials with various Nano-silica concentrations (0.25–1 wt.%), on drag reduction in the single-phase flow regime was investigated. Among the conditions investigated, optimal agreement with experimental results and highest drag reduction was recorded at 0.75 wt.% Nano-silica concentration at a Reynolds number of 13,931. Drag reduction has been found to increase with increasing concentrations of nanoparticles for fixed Reynolds numbers. For a fixed nanoparticle concentration, higher Reynolds number is also found to yield better drag reduction. These results confirm the effectiveness of the crude oil optimized using the nanoparticles in reducing the flow resistance under turbulent flow.

In case of poor-quality oil refining in the oil pipeline, water accumulations are formed, increasing hydraulic losses during transportation and contributing to corrosion processes. Hydrodynamic cleaning, which uses pumped oil flow, has been investigated due to its cost-effectiveness and adaptability for pipelines of varying diameters. This study develops a finite element hydrodynamic model to simulate the removal of water accumulations from inclined pipelines (inclination angle α = 45°). The model reveals a clear relationship between inlet velocity and multiphase flow patterns, demonstrating transitions from stratified flow (ST) at velocities below 0.1 m/s, to stratified with mixing (ST&MI) at 0.1–0.2 m/s, and finally to a dispersed water-in-oil (DW/O) pattern beyond 0.2 m/s. These velocity transitions are achieved in controlled steps: a steady increase to 0.1 m/s within 20 seconds, followed by acceleration phases reaching 0.25 m/s by 100 seconds. The DW/O regime exhibits the highest cleaning efficiency, reducing water volume from 660 ml to 273.29 ml over 125 seconds—a 58.5% reduction. The analysis further shows an initial rise in pressure gradient within the ST regime, peaking during the first plateau (0.1 m/s) before stabilizing and significantly declining in the DW/O regime at velocities exceeding 0.25 m/s. These findings emphasize the importance of optimizing flow velocity to achieve effective water removal while minimizing hydraulic losses. The study also highlights limitations in existing experimental setups, which predominantly use small diameters (<50 mm), and underscores the need for larger-scale experiments to validate these findings in real-world pipeline operations.

Rapid increase in the demand for gas has turned what was a buyer's market to a seller's market. As a result, pricing of gas price has become an ever more important issue that is under discussion by many experts. There are various methods of pricing defined with regard to theoretical issues and trade principles, but only some of these are applicable at the present time and others have remained more theoretical. Most gas exporting countries wish to have their gas priced at the equivalent level of oil prices, in terms of energy content or at least have gas price changes at the same rate as for petroleum prices, in order to encourage expansion of gas development projects. This is why in European countries the index of Oceania and Asian LNG prices is based on petroleum prices. This is also the case in Japan as the main LNG importer. It is expected that gas demand increases significantly in the long run, compared to other fuel resources. It is therefore expected that natural gas prices will continue their upward trend in the future.A study of the natural gas pricing process shows that unlike LNG, the price of natural gas is often lower than other energy alternatives (petroleum and oil products). There are two specific features of gas trade that are different from petroleum transactions, namely: 1) intense interdependence of exporter and importer due to the impossibility of saving gas at least during the contract period and 2) high risk of investment. Considering these particular features, prices mentioned in contracts should be calculated in such a way as to maintain gas supply security while providing the possibility of changing the contract price in case there is a change in other fuel prices (especially competing fuels), in order to maintain suppliers' interest. Thus, main principles to be considered in negotiation of gas export are: determining the relational index of gas and petroleum prices, the fixed portion of price, minimum and maximum prices, and determining the time period for price revisions in the gas pricing formula. The gas price has to be fixed in a competitive manner in relation to other fuel prices the present paper assesses the mechanisms of pricing gas export through pipelines and compares it to the other mechanisms and analyzes its future challenges.

Drag reduction prediction plays an important role in oil and gas industries. Due to the nonlinearity and instability of drag reduction, the precision of the commonly used conventional methods, including regression analyses, has been limited. A prediction model based on support vector regression (SVR) is presented in this paper to predict drag reduction by nanofluids in single-phase flow of water through horizontal pipes. To construct an effective SVR model, the SVR parameters must be set carefully. This study proposes a hybrid approach, known as support vector regression-genetic algorithm (SVR-GA), which searches for the optimal SVR parameters using GA, and accepts the optimal parameters to create the SVR models. The results indicated that the obtained drag reduction values by the proposed model are in good agreement with the experimental data. The performance of the SVR-GA model was compared with multiple linear regression (MLR). The coefficient of determination (R2) of 0. 9485 and 0. 8740; mean square error (MSE) of 0. 01177 and 0. 01772, for experimental and predicted data by SVR-GA and MLR models were obtained, respectively. This result shows that SVR-GA can be applied as an effective approach to predict drag reduction.

Background and Aim: Using intra cranial reference lines is inherently unreliable for assessment of anterior-posterior jaw relationships. However, they are being widely used for cephalometric evaluation and diagnosis and treatment planning of orthodontic patient. The aim of this study was to evaluate the correlation of the TH/AB and TH-Wits to the common horizontal and vertical analyses. Materials and Methods: This cross sectional descriptive study was conducted with 40 adults (20 male, 20 female) who were between 18-24 years-old and had no history of craniofacial disorders. Lateral cephalometries were taken for all patients, using Natural Head Position (NHP). All the cephalograms were taken by the same radiologist and were traced by same person. Two orthodontists approved the results and the kappa statistics was calculated to determin intra-examiner agreement level. Pearson correlation coefficient value was determined between TH-Wits, TH/AB and horizontal parameters (Wits, Harvold, Wylie, APP-BPP, and ANB angle) and vertical parameters (Sn-GoGn, S-Go/N-Gn, TH-GoGn and sum of posterior angles). The correlation analysis was used in order to determine the relationship between these parameters. Results: The results revealed that the highest correlation in horizontal direction was observed between TH-Wits, TH/AB; and ANB (0.73) and APP-BPP (0.68 & 0.61). In vertical direction, the highest correlation was demonstrated between TH-Wits, TH/AB; and sum of posterior angles (0.75 & 0.35). Conclusion: In using TH-Wits and TH/AB, the effect of changes in vertical dimension and the lack of significant correlation between these parameters and linear horizontal analysis should be considered.

This paper is concerned with asphaltene deposition in fluid flowing through pipelines. Brownian diffusion and drag, gravitational, thermophoresis, buoyancy, and shear removal are considered as possible mechanisms in the asphaltene deposition process. The thermo-physical properties of the fluid were obtained from Iranian oil fields. A model was used in the pipeline deposition modeling to predict the asphaltene deposition rates under flow conditions. The effects of particle size, temperature gradient, and fluid velocity were studied on asphaltene deposition rate. The results showed that, among the above-mentioned mechanisms, the gravitational and thermophoresis forces played a significant role in the formation of the deposit under the flow conditions. To verify the model, some predictions were compared with the available aerosol deposition data in the literature.

Enforcement of public policies is an important concern of most countries, especially developing countries. Weakness of horizontal policy management and lack of coordination in enforcing these policies are obstacles to achieving this purpose. The article emphasizes on the increasing role of horizontal coordination in Iran and other countries in the areas of accountability and good governance in government. Religious and national values, including consultation in matters, promotion of good and prevention of evil, and roles of justice and equity in Iranian Islamic society support this theory. Lacking a native Iranian-Islamic model of management and resistance of the state management system to fundamental changes are recognized as important obstacles to horizontal coordination. The article also emphasizes on coordination between policy-making bodies in the national level, including the executive, judiciary and legislature, in order to achieving horizontal coordination. Using administrative automation for making administrative systems transparent and attempting to operationalize morals and honesty and hard work based on religious values and national culture are suggested as strategies for strengthening horizontal coordination within state.

Various destructive and nondestructive methods are used for in line inspection of pipelines. A pipe may fail because of different causes such as corrosion, pitting, stress corrosion cracking (SCC), weld cracks and mechanical impacts and damages. Corrosion failures in a pipe can take place in different ways, some of them are easy to detect and others require special facilities and methods. The best selection of the inspection tools depends on the type of application, mechanism of corrosion, chemical environment and the material. This paper investigates and compares different types of in-line inspection tools for pipelines and compare their advantages and disadvantages. Today, the most common method for In Line Inspection of pipelines is Magnetic Flux Leakage (MFL), which is used for detection of wall thickness reduction of pipelines, various cracks, corrosion and pitting in pipes. Therefore, it can’t be applied for nonmagnetic materials. The Eddy Current (EC) test is a non-contact test with relatively low velocity which is sensitive to the stand off from the material surface during the test and it is used only for conductive materials. Ultrasonic testing is a common method with high accuracy. It is widely used for detection of different defects and is based on sending short wavelength high frequency ultrasonic waves into the material and receiving their reflections. By interpreting the results, various defects and reduction in the wall thickness of the pipes can be detected. Acoustic Emission (AE) testing, which is based on interpretation of elastic deformations, elastic strain energy changes and stress distribution, is not considered as a common test for inspection of pipelines, yet. Electromagnetic Acoustic Transducers (EMAT) are a new type of ultrasonic testing method which do not require liquid coupling but should be used at a definite distance from the pipe wall during the test. It is concluded that the fastest and most reliable method for In-Line Inspection (ILI) of pipelines is currently the Magnetic Flux Leakage (MFL) method.