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Integrated ethylene oxide/ethylene glycols (EO/EG) plants are prominent energy consumers in the petrochemical sector, particularly concerning high‐pressure steam (HPS) usage which holds the potential for substantial energy savings. This study focuses on an unexplored territory: Examining the impact of EO catalyst type, selectivity, and glycols production capacity on HPS import in a plant in the Pars Special Economic Energy Zone (PSEEZ). Utilizing Python3 for data preprocessing and ordinary least squares linear regression analysis, we evaluate how varying catalyst loads and production scenarios influence HPS import. Regression models are created, encompassing normal and efficient HPS import scenarios, yielding positive outcomes in terms of correlation, mean error percentage, and R2 analysis. Comparing normal and efficient HPS import models highlights potential savings, uncovering opportunities to conserve between 45 and over 200 tonnes per day of HPS. We also explore the plant's HPS behaviour under 1% selectivity and production capacity reductions. Notably, catalyst activity decline markedly escalates HPS import for hybrid catalysts, while selectivity decline decreases HPS import for high‐activity catalysts. The models demonstrate that HPS import is ~150 tonnes per day more sensitive to a 1% change in selectivity compared to production capacity. Moreover, when comparing high activity and hybrid catalyst scenarios in normal and efficient cases, the most substantial HPS import difference arises under conditions of low selectivity, amounting to nearly 200 tonnes per day. Our methodology applies to other EO/EG plants. It is incorporated into our plant's energy management system, enabling continuous monitoring of steam import behaviour relative to catalyst and plant performance. [ABSTRACT FROM AUTHOR]

Dust is an important atmospheric phenomena that occurs in spring and summer in many regions, including Iran and its neighboring countries. Considered one of the most important challenges of the last century, this phenomenon occurs on a global scale in arid and semi-arid regions. Because of changes in climate and vegetation as well as progressive processes of soil erosion and the disturbances resulting from them, the sensitivity of regions to rapid erosion will have important reactions on the region's climate and desertification. Therefore, the current research investigated the concentration and distribution of fine dust under the influence of meteorological parameters using the GCM climate model and attempted to determine the effect of climate change on the concentration of the relevant pollutant in the coming years. In this study, the CALPUFF model considered the temporal and spatial effects of weather conditions on the transfer, transformation, and removal of atmospheric pollutants. The emission rate of the PM10 pollutant was estimated. The results indicated that the increase in greenhouse gas emissions and changes in climate variables in the near future will cause the distribution of suspended particles one of the important pollutants to increase significantly. The results also revealed a significant relationship between the degradation of air quality and the trend of air warming during the period 2046-2065. [ABSTRACT FROM AUTHOR]

More attention has been paid to Damage detection in offshore jacket platforms (OJP) because of repair and maintenance issues. Damage detection using modal data from a few sensors is one of the main important subjects that researchers have paid attention to it. The inverse Vibration Problem (IVP) technique does not need modal data in all nodes of OJP but first modal data in different levels of platform and principal degrees of freedom could be sufficient. Since the complex structural model becomes a reduced shear building by implementing this technique, there must be a reduced equivalent stiffness matrix for the healthy structure to make the comparison for damage detection. This paper deals with the formulation and implementation of IVP technique in corporation of the proper method for calculation of equivalent level stiffness. The proper method was selected based on a comparison of modal data obtained from full and reduced models using comparison tools like the MAC coefficient. Also, damage detection in a typical OJP model under a specific damage scenario was investigated numerically and experimentally and the results show the reliable performance of the methodology. A damage detection flowchart is suggested to detect damage location properly. It is developed mainly based on geometrical couplings in OJP structure in damaged conditions and the method leads to damage location exactly and maximum error in damage prediction is obtained at about 12%. [ABSTRACT FROM AUTHOR]

The present paper focuses on the simulation of vortex-induced vibration (VIV) of a rigid, smooth circular cylinder with elastic supports subject to a cross-flow at the subcritical regime of Reynolds number, 30,000< Re <80,000. The circular cylinder is allowed to move in one degree-of-freedom (DOF), heave. Unsteady Reynolds-averaged Navier-Stokes (URANS) equations are solved with Menter's k — ω based Shear Stress Transport based Scale-Adaptive Simulation, SAS-SST, turbulence model, and two-equation transition transport γ — θ model. The transport equations are discretized using the Finite Volume Method (FVM). The numerical amplitude and frequency ratio is compared against the experiments conducted in the Marine Renewable Energy Laboratory (MRELab) at the University of Michigan. The angle in which the computed lift leads the displacement in VIV is compared against experimental results reported by Cornell-ONR Water Channel as well. The existence of the initial, upper, and lower VIV response branches is demonstrated. Wake vortex pattern mode has been studied in the different branches of VIV. The time records of the added mass force coefficient and the vortex force coefficient are obtained. Then, the time-averaged phase angle of the vortex and added mass force coefficients are compared against the experimental results. Lastly, the time records of the phase angle in different branches of VIV are shown and analyzed. [ABSTRACT FROM AUTHOR]

Roll control of the Autonomous Underwater Vehicles (AUVs) is a significant issue in the current field of research for many researchers in the subject of AUV control system designation. Especially at higher speeds, the roll angle generated by a single rotating propeller or other external disturbances can considerably influence the whole dynamics and therefore the operation of the vehicle. In this paper, the utilisation of a system of contra-rotating-propellers (CRP) to enhance the roll dynamics of an AUV is evaluated by developing a six-degrees-of-freedom (6DOF) dynamics and control systems' simulator. The results show that: 1. The single propeller system can cause roll angle deflections affecting the heading angle and depth of AUV depending on the forward speed. 2. Using the contra-rotating system with a proper roll controller can enhance the roll dynamics of the vehicle, particularly for the real-time roll stabilisation and maneuvering goals. [ABSTRACT FROM AUTHOR]

Floating wind turbines are subjected to highly dynamic and complicated environmental conditions leading to significant platform motions and structural vibrations during operation and survival conditions. These motions and vibrations alter the induced loading characteristics; and consequently, affect the dynamic behavior of the system. In order to better understand the influence of such motions and structural vibrations, herein elastic structural disturbance of tower, on the system behavior, the spectral and statistical characteristics of a floating wind turbine dynamic responses under operational and survival conditions are fully explored using a fully coupled aero-hydro-servo-multi-rigid-flexible-body model. The spectral comparison results showed the important role of aerodynamic damping in reducing the high-frequency resonant responses in operational conditions. These analyses also revealed the effects of tower elasticity in shifting and amplifying high-frequency resonant responses. The statistical comparison results showed that the mean values of the responses are dominated by wind loads and the maximum and standard deviations of the responses are mainly induced by the combination of support platform motions and wave loads. It was also shown that elastic structural deformation of tower enlarges the statistical characteristics of the responses, especially when the system is subjected to both wind and wave loadings. [ABSTRACT FROM AUTHOR]

This study aims at identifying the parameters that govern the environmental costs in oil and gas projects. An initial conceptual model was proposed. Next, the costs of environmental management work packages were estimated, separately and were applied in project control tools (WBS/CBS). Then, an environmental parametric cost model was designed to determine the environmental costs and relevant weighting factors. The suggested model can be considered as an innovative approach to designate the environmental indicators in oil and gas projects. The validity of variables was investigated based on Delphi method. The results indicated that the project environmental management's weighting factor is 0.87% of total project's weighting factor. [ABSTRACT FROM AUTHOR]

The Peer-Bazar river delivers pollutants in the water bodies of Anzali International Wetland especially during flood events. Here, the two-dimensional (2D) finite volume hydrodynamic models for the prediction of nutrients are developed. The model is based on the mass balance equation including advection and diffusion transport and chemical and biological transformation considering the impact of inflowing river and climate change. The model is formulated to simulate nutrients such as Amonia-Nitrogen (NH3-N), Nitrate (NO3-N) or overall Total Nitrogen (TN), Phosphorus (PO43-) or TP, Dissolved Oxygen (DO) and Total Dissolved Solids (TDS) and prediction of spatial and temporal distributions of concentration of each parameter in the Peer-bazar estuaries leading to the Anzali International Wetland. Ten points of the Peer-bazar River were studied during an 18-month period from June 2014 to December 2015. The simulation and numerical analysis of water quality parameters were conducted in a 2-dimensional approach using the geometric and topographic data and imposing boundary conditions. This research used the software developed by the author, FLOW-3D mathematical model, and HEC-RAS for simulation and qualitative evaluation of the river. Results revealed that the mean concentration of phosphorous, nitrogen and TDS exceeded the permissible limits reported by the European Directive 80/778/EEC and OECD and USEPA standards. Therefore, water of the region is subject to the advanced eutrophic conditions. Simulation predictions showed that the variation in TDS and nutrients contents will increase in the next coming years and the region will reach to the stable conditions. Using regression, a relationship between EC and TDS was obtained in the next step. Comparing the results obtained by the simulator and the values measured in laboratory indicated the suitable performance of reference values. [ABSTRACT FROM AUTHOR]

This paper empirically examines the hydrodynamic performances of squat submarines under the resistance and wave tests beside numerical investigation of pressure drag reduction techniques. Despite vast information about the operation of the streamlined fluid vessels, there is not much information about the geometries and hydrodynamic behaviors of squat vessels with L/D ratios below four. This study experimentally investigates the impacts of various relative depths and flow inclinations, intending to find drag, heave, and sway forces at the velocities of 0.5, 1.0, 1.5, 2.0, and 2.5-m/s. A one-tenth scaled model of a squat submarine is examined under the resistance and wave train scenarios as the captive model in the towing tank experiments via 110 unique testing scenarios. Then, different pressure drag reduction techniques on the full-scale submarine are evaluated numerically at one-phase fluid by developing stern geometric optimization, nose rod devices, water corridors, and surface patterns at the bow and stern. Results present drag forces increase up to 150% at the 0.5D level for the resistance and wave tests due to the influences of the free surface water. The drag coefficients at the fully submerged depth of 6D differ by up to 13.3% between the numerical and experimental evaluations. • The effects of the surface water create a critical zone on the 0.5D depth level. • The drag and heave forces decrease on the surface depth level. • The heave force variations generally show a higher reduction rate. • The output trends of the wave train tests are similar to the resistance tests. • The passive pressure drag reductions are functional for submarine. [ABSTRACT FROM AUTHOR]

Recently, the mechanisms of natural undulatory locomotion of aquatic animal swimming have become one of the most significant issues for the researchers, swimmers and engineers. This study aims to elucidate and compare the propulsive vortical signature and performance of backward (negative undulation) and forward (positive undulation) travelling waves through a typical fishlike propulsor by a systematic numerical study. The numerical approach uses a pressure-based finite volume method solver to solve Navier–Stokes equations in an arbitrary Lagrangian–Eulerian framework domain containing a two-dimensional NACA 0012 foil moving with prescribed kinematics. Some of the important findings are: (1) time-dependent forces and pitching moments show that both mechanisms suffer from the energy losses; however, the negative undulations show less energy losses, (2) Strouhal number of undulations shows a transition point from drag-dominated regime to thrust-dominated regime for both mechanisms and a transition point from thrust-dominated regime to drag-dominated regime for positive undulation, (3) the consumed power plot shows that at lower and medium St, both mechanisms consume closely same powers, while, at higher St, the negative undulation consumes more power, (4) the efficiency plots show that the efficiency of the positive undulation is close to zero, while, the negative undulation reaches considerably higher performances, (5) low St vortical patterns of the mechanisms show some similarity, while, the patterns at medium and high St reveal appreciable discrepancies, and (6) the most significant difference between the vortical patterns of the mechanisms is appearing more regular and stronger vortices in the wake of the negative undulation. [ABSTRACT FROM AUTHOR]

Noise is one of the most important sources of pollution in metropolitan areas, it causes discomfort for urban residents and hampers the efficiency of work force. Currently, there is an urgent need to conduct basic studies on this issue in order to attain a mathematical model for prediction of traffic noise levels in the major cities of Iran. This article is the result of research conducted in the city of Hamadan in 2005 with the ultimate objective of setting up a traffic noise model based on the traffic conditions of Iranian cities. For this study, main access roads of Hamadan city were divided in 64 segments and after careful considerations, 94 measuring stations were assigned to them. For the optimisation of noise measurement intervals in each station and the determination of background noise impact on the main traffic noise, 30 stations with the specifications of the target stations were randomly selected at the pilot stage. In all the pilot stations, the background sound pressure level (SPLb), Leq, SPLmax, L10 were measured simultaneously in 10, 30 and 60 minute intervals (in random non-holiday days at random hours). The measurements were made 3 meters away form the road side. Pilot results indicated that the mean equivalent sound pressure levels at the measuring stations in 10, 30 and 60 minute intervals were 70.76±2.11 dBA, 30 minutes 70.88±2.19 dBA, and 60 minutes 70.93±2.13dBA respectively. The mean background sound pressure level at the stations was 60.77±5.04 dBA. The results of the traffic noise measurements at the research stations through the comparison of mean values (Variance Analysis) indicated that there is no meaningful deviation between the Leq in the above-mentioned time intervals (10, 30 and 60 minutes) in the hourly measurements (P= 0.998). In the pilot phase, it was determined that the background noise level did not impose a considerable impact on the main traffic noise and it was possible to make 10-minute interval measurements to forecast the 30-minute and 60-minute interval equivalent levels. Therefore in the main phase of study with the utilisation of the 10-minute interval results collected from each of the 94 stations, a total of 282 measurements including 2 daily-hour and one nightly-hour measurements were conducted. The final results revealed that the average Leq in all stations was 69.04±4.25 dBA, the average speed of vehicles was 44.57±11.46 km/hr and average traffic load was 1231.9±910.2 V/hr. Moreover, the results indicated that the Leq in the studied roads were exceeding the allowable levels of urban noise pollution and there was a meaningful deviation between equivalent levels during a 24-hour period, traffic load and various vehicle speeds (P=0.003). [ABSTRACT FROM AUTHOR]

Noise is one of the most important sources of pollution in metropolitan areas, it causes discomfort for urban residents and hampers the efficiency of the work force. Currently, there is an urgent need to conduct basic studies on this issue in order to attain a mathematical model for prediction of traffic noise levels in the major cities of Iran. This article is the result of research conducted in the city of Hamadan in 2005 with the ultimate objective of setting up a traffic noise model based on the traffic conditions of Iranian cities. For this study, main access roads of Hamadan city were divided in 64 segments and after careful considerations, 94 measuring stations were assigned to them. For the optimisation of noise measurement intervals in each station and the determination of background noise impact on the main traffic noise, 30 stations with the specifications of the target stations were randomly selected at the pilot stage. In all the pilot stations, the background sound pressure level (SPLb), Leq, SPLmax, L10 were measured simultaneously in 10, 30 and 60 minute intervals (in random non-holiday days at random hours). The measurements were made 3 meters away from the road side. Pilot results indicated that the mean equivalent sound pressure levels at the measuring stations in 10, 30 and 60 minute intervals were 70.76±2.11 dBA, 30 minutes 70.88±2.19 dBA, and 60 minutes 70.93±2.13dBA respectively. The mean background sound pressure level at the stations was 60.77±5.04 dBA. The results of the traffic noise measurements at the research stations through the comparison of mean values (Variance Analysis) indicated that there is no meaningful deviation between the Leq in the above-mentioned time intervals (10, 30 and 60 minutes) in the hourly measurements (P= 0.998). In the pilot phase, it was determined that the background noise level did not impose a considerable impact on the main traffic noise and it was possible to make 10-minute interval measurements to forecast the 30-minute and 60-minute interval equivalent levels. Therefore in the main phase of study with the utilisation of the 10-minute interval results collected from each of the 94 stations, a total of 282 measurements including 2 daily-hour and one nightly-hour measurements were conducted. The final results revealed that the average Leq in all stations was 69.04±4.25 dBA, the average speed of vehicles was 44.57±11.46 km/hr and average traffic load was 1231.9 ± 910.2 V/hr. Moreover, the results indicated that the Leq in the studied roads were exceeding the allowable levels of urban noise pollution and there was a meaningful deviation between equivalent levels during a 24-hour period, traffic load and various vehicle speeds (P= 0.003). [ABSTRACT FROM AUTHOR]

Manta ray swimming or bio-inspiration propulsion system, as a special type of marine propulsion system, is used for submersible vehicles that require high-speed maneuverability and stability, such as glider and AUV. In a manta ray swimming, the thrust force is generated by a couple of undulation and oscillation of wing, so that the direction of undulation wave and oscillation is upright and perpendicular to the direction of thrust force, respectively. It is possible to combine these two movement modes (flapping motion) on the three-dimensional model without considering the effects of wing twisting and flexibility to simplify and better understand the physical behaviors or special study of this movement on the manta rays as a marine glider. This study uses the computational fluid dynamics (CFD) tool to numerically simulate the complex unsteady vortical structure of flow due to the manta ray's flapping motion. The incompressible Navier-Stokes equations are solved using a pressure-based finite-volume method. In this research, the effect of kinematic parameters such as Strouhal number, non-dimensional heaving amplitude (h*), the maximum angle of attack (α 0), the oscillation velocity on hydrodynamic performance during flapping motion is studied by applying a couple of heaving and pitching movement on manta ray mid-section (2D) and manta ray model (3D). The results show that although both thrust production and power consumption values are low in the 3D model, they attain higher efficiency than the 2D model. [ABSTRACT FROM AUTHOR]

The hydrodynamics and energetics of bioinspired oscillating mechanisms have received significant attentions by engineers and biologists to develop the underwater and air vehicles. Undulating and pure heaving (or plunging) motions are two significant mechanisms which are utilized in nature to provide propulsive, maneuvering, and stabilization forces. This study aims to elucidate and compare the propulsive vortical signature and performance of these two important natural mechanisms through a systematic numerical study. Navier-Stokes equations are solved, by a pressure-based finite volume method solver, in an arbitrary Lagrangian-Eulerian (ALE) framework domain containing a 2D NACA0012 foil moving with prescribed kinematics. Some of the important findings are (1) the thrust production of the heaving foil begins at lower St and has a greater growing slope with respect to the St; (2) the undulating mechanism has some limitations to produce high thrust forces; (3) the undulating foil shows a lower power consumption and higher efficiency; (4) changing the Reynolds number (Re) in a constant St affects the performance of the oscillations; and (5) there is a distinguishable appearance of leading edge vortices in the wake of the heaving foil without observable ones in the wake of the undulating foil, especially at higher St.