A New Risk-Based Method in Decision Making to Create Dust Sources Maps: A Case Study of Saudi Arabia

Dust storms are one of the major causes of the destruction of natural ecosystems and human infrastructure worldwide. Therefore, the identification and mapping of susceptible regions to dust storm formation (SRDSFs) is of great importance. Determining SRDSFs by considering the concept of risk in the decision-making process and the kind of manager’s attitude and planning can be very valuable in dedicating financial resources and time to identifying and controlling the negative impacts of SRDSFs. The purpose of this study was to present a new risk-based method in decision making to create SRDSF maps of pessimistic and optimistic scenarios. To achieve the purpose of this research, effective criteria obtained from various sources were used, including simulated surface data, satellite products, and soil data of Saudi Arabia. These effective criteria included vegetation cover, soil moisture, soil erodibility, wind speed, precipitation, and absolute air humidity. For this purpose, the ordered weighted averaging (OWA) model was employed to generate existing SRDSF maps in different scenarios. The results showed that the wind speed and precipitation criteria had the highest and lowest impact in identifying dust centers, respectively. The areas identified as SRDSFs in very pessimistic, pessimistic, neutral, optimistic, and very optimistic scenarios were 85,950, 168,275, 255,225, 410,000, and 596,500 km2, respectively. The overall accuracy of very pessimistic, pessimistic, neutral, optimistic, and very optimistic scenarios were 84.1, 83.3, 81.6, 78.2, and 73.2%, respectively. The very pessimistic scenario can identify the SRDSFs in the study area with higher accuracy. The overall accuracy of the results of these scenarios compared to the dust sources obtained from the previous studies were 92.7, 94.2, 95.1, 88.4, and 79.7% respectively. The dust sources identified in the previous studies have a higher agreement with the results of the neutral scenario. The proposed method has high flexibility in producing a wide range of SRDSF maps in very pessimistic to very optimistic scenarios. The results of the pessimistic scenarios are suitable for risk-averse managers with limited financial resources and time, and the results of the optimistic scenarios are suitable for risk-taking managers with sufficient financial resources and time.Peer Reviewe

Laboratory testbed and methods for flexible characterization of thermal and fluid dynamic behaviour of double skin facades

publishedVersio

Effect of stator blades on the startup dynamics of a vertical axis wind turbine.

Vertical Axis Wind Turbines (VAWTs) are omni-directional, low-cost, low-efficiency wind power extractors. A conventional drag-based VAWT consists of multiple thin rotor blades with a typical peak Tip Speed Ratio (λ) of less than 1. Their lower cut-in speed and maintenance cost make them ideal for power generation in urban environments. Numerous studies have been carried out analysing steady operation of VAWTs and quantifying their performance characteristics; however, minimal attention has been paid to their start-up dynamics. There are a few recent studies in which start-up dynamics of lift-based VAWTs have been analysed, but such studies for drag-based VAWTs are severely limited. In this study, start-up dynamics of a conventional multi-blade drag-based VAWT have been numerically investigated using a time-dependant Computational Fluid Dynamics (CFD) solver. In order to enhance the start-up characteristics of the drag-based VAWT, a stator has been integrated in the design assembly. The numerical results obtained in this study indicate that an appropriately designed stator can significantly enhance the start-up of a VAWT by directing the flow towards the rotor blades, leading to higher rotational velocity (ω) and λ. With the addition of a stator, the flow fields downstream the VAWT becomes more uniform

Reliability analysis of 15MW horizontal axis wind turbine rotor blades using fluid-structure interaction simulation and adaptive kriging model

Over the course of the last four decades, the rotor diameter of Horizontal Axis Wind Turbines (HAWTs) has undergone a substantial increase, expanding from 15 m (30 kW) to an impressive 240 m (15MW), primarily aimed at enhancing their power generation capacity. This growth in blade swept area, however, gives rise to heightened loads, stresses and deflections, imposing more rigorous demands on the structural robustness of these components. To prevent sudden failure and to plan effective inspection, maintenance, and repair activities, it is vital to estimate the reliability of the rotor blades by considering all the forces (aerodynamic and structural dynamics) acting on them over the turbine’s lifespan. This research proposes a comprehensive methodology that seamlessly combines fluid-structure interaction (FSI) simulation, Kriging model/algorithm and Adaptive Kriging Monte Carlo Simulation (AKMCS) to assess the reliability of the HAWT rotor blades. Firstly, high-fidelity FSI simulations are performed to investigate the dynamic response of the rotor blade under varying wind conditions. Recognizing the computationally intensive nature and time-consuming aspects of FSI simulations, a judicious approach involves harnessing an economical Kriging model as a surrogate. This surrogate model adeptly predicts blade deflection along its length, utilizing training and testing data derived from FSI simulations. Impressively, the Kriging model predicts blade deflection 400 times faster than the FSI simulations, showcasing its enhanced efficiency. The optimized surrogate model is then used to estimate the flap wise blade tip deflection for one million wind speed samples generated using Weibull distribution. Thereafter, to evaluate the reliability of the blades, statistical modeling using methods such as Monte Carlo Simulation (MCS), AKMCS is performed. The results demonstrate the faster convergence of AKMCS requiring only 21 samples, as opposed to 1 million samples for MCS with minimal reduction in the precision of the estimated probability of failure (Pf) and reliability index (β). Demonstrated on the backdrop of an IEA-15MW offshore reference WT rotor blade, the proposed methodology underscores its potential to be seamlessly incorporated into the creation of WT digital twins, due to its near real-time predictive capabilities for Pf and β assessments.Reliability analysis of 15MW horizontal axis wind turbine rotor blades using fluid-structure interaction simulation and adaptive kriging modelacceptedVersio

Quantifying the Impact of Dust Sources on Urban Physical Growth and Vegetation Status: A Case Study of Saudi Arabia

Recently, dust has created many problems, including negative effects on health, and environmental and economic costs, for people who live both near to and far from sources of dust. The aim of this study is to evaluate and quantify the impact of dust sources located inside Saudi Arabia on the physical growth and vegetation status of cities. In order to do so, satellite data sets, simulated surface data, and soil data for Saudi Arabia from 2000 to 2021 were used. In the first step, a dust sources map of the study area was generated using multi-criteria decision analysis. Land surface temperature (LST), vegetation cover, soil moisture, precipitation, air humidity, wind speed, and soil erodibility factors were considered as effective criteria in identifying dust sources. In the second step, built-up land and vegetation status maps of major cities located at different distances from dust sources were generated for different years based on spectral indicators. Then, the spatiaotemporal change of built-up land and vegetation status of the study area and major cities were extracted. Finally, impacts of major dust sources on urban physical growth and vegetation were quantified. The importance degrees of soil erodibility, wind speed, soil moisture, vegetation cover, LST, air humidity, and precipitation to identify dust sources were 0.22, 0.20, 0.16, 0.15, 0.14, 0.07, and 0.05, respectively. Thirteen major dust sources (with at least 8 years of repetition) were identified in the study area based on the overlap of the effective criteria. The identified major dust sources had about 300 days with Aerosol Optical Depth (AOD) values greater than 0.85, which indicates that these dust sources are active. The location of the nine major dust sources identified in this study corresponds to the location of the dust sources identified in previous studies. The physical growth rates of cities located 400 km from a major dust source (DMDS) are 46.2% and 95.4%, respectively. The reduction rates of average annual normalized difference vegetation index (NDVI) in these sub-regions are 0.006 and 0.002, respectively. The reduction rate of the intensity of vegetation cover in the sub-region close to dust sources is three times higher than that of the sub-region farther from dust sources. The coefficients of determination (R2) between the DMDS and urban growth rate and the NDVI change rate are 0.52 and 0.73, respectively, which indicates that dust sources have a significant impact on the physical growth of cities and their vegetation status.Institutional Fund ProjectsPeer Reviewe

Effect of leading-edge erosion on the performance of offshore horizontal axis wind turbine using BEM method

publishedVersio

1-(4-Chloro­phen­yl)-2-[4-hy­droxy-3-(3-meth­oxy­benzo­yl)-1,1-dioxo-2H-1λ6,2-benzothia­zin-2-yl]ethanone

In the title mol­ecule, C24H18ClNO6S, the heterocyclic thia­zine ring adopts a half-chair conformation with the S and N atoms displaced by 0.406 (5) and 0.444 (5) Å, respectively, on opposite sides of the mean plane formed by the remaining ring atoms. The meth­oxy­benzoyl and the chloro­phenyl rings lie roughly parallel to each other, with a dihedral angle between the mean planes of these rings of 8.86 (10)°. The mol­ecular structure is consolidated by intra­molecular O—H⋯O and C—H⋯O inter­actions and the crystal packing is stabilized by inter­molecular O—H⋯O and C—H⋯Cl hydrogen bonds

Numerical investigations on the transient aerodynamic performance characterization of a multibladed vertical axis wind turbine.

The use of vertical axis wind turbines (VAWTs) in urban environments is on the rise due to their relatively smaller size, simpler design, lower manufacturing and maintenance costs, and above all, due to their omnidirectionality. The multibladed drag-based VAWT has been identified as a design configuration with superior aerodynamic performance. Numerous studies have been carried out in order to better understand the complex aerodynamic performance of multibladed VAWTs employing steady-state or quasi-steady numerical methods. The transient aerodynamics associated with a multibladed VAWT, especially the time–history of the power coefficient of each blade, has not been reported in the published literature. This information is important for the identification of individual blade’s orientation when producing negative torque. The current study aims to bridge this gap in the literature through real-time tracking of the rotor blade's aerodynamic performance characteristics during one complete revolution. Numerical investigations were carried out using advanced computational fluid dynamics (CFD)-based techniques for a tip speed ratio of 0 to 1. The results indicate that transient aerodynamic characterization is 13% more accurate in predicting the power generation from the VAWT. While steady-state performance characterization indicates a negative power coefficient (Cp) at λ = 0.65, transient analysis suggests that this happens at λ = 0.75

A projected finite element update method for inverse identification of material constitutive parameters in transversely isotropic laminates

In this paper, a novel application of Finite Element Update Method (FEUM) is proposed for the inverse identification of material constitutive parameters in transversely isotropic laminates. Two-dimensional Digital Image Correlation (2D–DIC) is used for full-field measurements which is required for the identification process. Instead of measuring the in-plane displacements, which is a well-known application of 2D–DIC, we seek to measure the pseudo-displacements resulting from out-of-plane (towards camera) deflection of plate under a point load. These pseudo-displacements are basically the perspective projection of the three dimensional displacement fields on the image-plane of the image acquisition system. The cost function in this method is defined in terms of these projections instead of the true displacements – and hence the name Projected Finite Element Update Method (PFEUM). In this article, identification of in-plane elastic moduli of Carbon Fiber Reinforced Plastic (CFRP) plate has been performed using plate bending experiments which show pre-dominantly out-of-plane deflection with little contribution from the in-plane displacements. Identification results are validated by direct experimental measurements of the unknown elastic constants as well as theoretical estimates based on volume ratio of constituents. The results show good conformance between estimated and target values for at least three material parameters namely E1, E2 and G12. Effects of experimental noise on parameter estimates has also been evaluated to explain the observed deviation in estimated parameters with current test configuration

Reverse-phase chromatographic determination and intrinsic stability behavior of 5-[(4-chlorophenoxy)methyl]-1,3,4-oxadiazole-2-thiol

The study describes the development and preliminary validation of a simple reverse phase chromatographic method for determination of a novel drug candidate, 5-[(4-chlorophenoxy)methyl]-1,3,4-oxadiazole-2-thiol (OXCPM), in bulk and stressed solution, in order to find out the intrinsic stability behavior of the compound. Isocratic elution was carried out at a flow rate of 1.0 mL min–1 through a Promosil C18 column maintained at 25 °C, using the mobile phase comprising acetonitrile and aqueous o-H3PO4 (pH 2.67) (1:1, V/V). Detection was performed at 258 nm. The response of the detector was linear in a concentration range of 1.25–50.00 µg mL–1 with the correlation coefficient of 0.9996 ± 0.0001. Cumulative intra-day, inter-day and inter-instrument accuracy (99.5 ± 1.0, 100.2 ± 1.0 and 100.3 ± 0.4 %, resp.) with RSD less than 5 % indicated that the method was accurate and precise. The resolution and selectivity factor (>2 and >1, resp.), particularly in copper metal- and dry-heat-stress solutions, depicted the selectivity of the method. OXCPM remained stable under hydrolytic (acidic and neutral pH, ≤ 37 °C), photolytic and moist heat stress conditions. Under alkaline conditions (hydrolytic and photolytic), polar products were formed and eluted very fast through the column (tR < 3.75 min). At room temperature, the compound was susceptible to oxidation by hydrogen peroxide and transition metals. The ionogram of most of the stress solutions indicated the presence of a product having m/z 256, which may be a result of N- or S- methylation or -SH oxidation. The results of the study indicate that the method is selective, sensitive and suitable to be used for determination of OXCPM in bulk and under stress conditions