Parametric Study Research Articles

Per- and polyfluoroalkyl substances (PFAS) in Ski waxes and snow from cross-country skiing in Germany - Comparative study of sum parameter and target analysis

Per- and polyfluoroalkyl substances (PFAS) are often environmentally exposed via discharge through human consumer products, such as ski waxes. In our study we analyzed various ski waxes from the 1980s and 2020s, to determine both the sum parameter values total fluorine (TF), extractable organically bound fluorine (EOF), hydrolysable organically bound fluorine (HOF) as well as targeted PFAS analysis. This showed that modern high-performance waxes contain up to 6 % TF, but also PFAS-free labelled ski waxes contain traces of PFAS with EOF/HOF values in the low mg kg-1 range. With the ban of all fluorine-based waxes with the start of the 2023/2024 winter season this will probably change soon. Moreover, we applied our analysis methods to snow samples from a frequently used cross country ski trail (Kammloipe) in the Ore Mountain region in Germany, assessing the potential PFAS entry/discharge through ski waxes. Melted snow samples from different spots were analyzed by the adsorbable organically bound fluorine (AOF) sum parameter and PFAS target analysis and confirmed the abrasion of the ski waxes into the snow. Moreover, on a PFAS hotspot also soil samples were analyzed, which indicate that PFAS from the ski waxes adsorb after snow melting into the soil.

Secure equitable subdivision number of graphs

A dominating set S of a graph G(V, E) is called a secure dominating set, if for each vertex x belongs to V(G) \ S there exists at least one vertex y in S such that y belongs to the neighbourhood of x and a vertex y can be replaced by a vertex x without losing domination property. A secure dominating set S is a secure equitable dominating set if for each x in V(G) \ S and the vertex y in S, which replaces x, we have |deg(x)-deg(y)| is less than or equal to 1. In this paper, we initiate the study of a new domination parameter, the secure equitable subdivision number of graphs. Also, we introduce the definitions of the secure equitable subdivision critical graphs and the secure equitable subdivision stable graphs. Further, we study the construction of a secure equitable subdivision critical graph.

Scattering of Oblique Water Waves by Two Vertical Barriers Over Trench-Type Bottom

The problem of scattering of oblique water waves by two surface-piercing vertical thin rigid barriers over a trench-like bottom is investigated within the framework of linear water wave theory. The eigenfunction expansion technique is used to obtain a system of algebraic equations, which is further solved using the algebraic Least squares method. The reflection and transmission coefficients are computed and contrasted with the prior results. Physical characteristics such as surface elevation and horizontal force on both barriers are also determined and depicted graphically against various parameters to see their behavior. It is possible to strategically construct barriers and trench-like bottoms to regulate how waves reflect and propagate. This might mitigate the wave impact on ships, improving the safety, effectiveness and longevity of ships navigating through the channels. The highlights of the given problem include comparing the impacts of different depth ratios and barrier placements, followed by a study of the modulation parameter to evaluate standing wave patterns in the trench region. The specific circumstances for the formation of the standing wave are identified. Hence, understanding this study is critical for safe navigation because standing waves may produce hazardous conditions for boats, making navigation difficult and causing substantial damage.

Development of idealized human aortic models for in vitro and in silico hemodynamic studies.

The aorta, a central component of the cardiovascular system, plays a pivotal role in ensuring blood circulation. Despite its importance, there is a notable lack of idealized models for experimental and computational studies. This study aims to develop computer-aided design (CAD) models for the idealized human aorta, intended for studying hemodynamics or solid mechanics in both in vitro and in silico settings. Various parameters were extracted from comprehensive literature sources to evaluate major anatomical characteristics of the aorta in healthy adults, including variations in aortic arch branches and corresponding dimensions. The idealized models were generated based on averages weighted by the cohort size of each study for several morphological parameters collected and compiled from image-based or cadaveric studies, as well as data from four recruited subjects. The models were used for hemodynamics assessment using particle image velocimetry (PIV) measurements and computational fluid dynamics (CFD) simulations. Two CAD models for the idealized human aorta were developed, focusing on the healthy population. The CFD simulations, which align closely with the PIV measurements, capture the main global flow features and wall shear stress patterns observed in patient-specific cases, demonstrating the capabilities of the designed models. The collected statistical data on the aorta and the two idealized aorta models, covering prevalent arch variants known as Normal and Bovine types, are shown to be useful for examining the hemodynamics of the aorta. They also hold promise for applications in designing medical devices where anatomical statistics are needed.

Additively Manufactured Porous Metallic Implants and Their Surface Modification for Biomedical Applications: A Review

The evolution of three dimensional (3D) printed porous metallic biomaterials and their clinical applications are currently receiving much consideration. Many research works have been focused on the shaping by 3D printing of lightweight metal implants with improved mechanical properties. In the same way, the effect of surface finishes on roughness and porosity distribution on biological properties is still debated. Therefore, several factors need to be addressed and revisited in this context. This review focuses on the importance of porous metallic implant design and its relationship with biological and mechanical properties. First, the additive manufacturing (AM) techniques for bio-inert metals and alloys will be discussed. The review will then introduce the most efficient surface treatments and coating approaches for biomedical porous metals to enhance bone tissue regeneration, prevent corrosion, reduce revision surgery and improve implant lifetime. A critical study of the various parameters impacting the biological properties will also be carried out in this review.

Aerodynamic Performance of a Hovering Cycloidal Rotor: A CFD Study with Experimental Validation

A three‐dimensional (3D) unsteady Reynolds averaged Navier‐Stokes (URANS) computational fluid dynamics (CFD) toolkit for cycloidal rotors was developed and used to perform a parametric study. It included blade aspect ratio, side disks, pitch mechanism, blade camber, and shaft size. The influence of the pitch rod length showed the importance of the lift distribution between the upstream and downstream parts of the rotor cylinder. The application of blade camber significantly affected thrust and power, while having a limited effect on efficiency. A similar effect was obtained by varying the pitch rod lengths. The presence of a central axis in the rotor had a negligible effect on efficiency. The most significant impact on efficiency came from the side disks, which behaved similarly to winglets on fixed‐wing aircraft. However, changing the aspect ratio of the blades showed a similar response to that of aircraft wings, but with a smaller effect, making it conceivable to fly a square-bladed cyclorotor without side disks. To verify the CFD model, a cycloidal rotor was also built using 3D printed parts and carbon fiber tubing. It was then operated on a test rig where thrust and power were measured for speeds ranging from 408 to 2528 RPM. On the test bench, the blades were pitched with a uniform asymmetric mechanism. The maximum nose‐up pitch angle in upstream of the rotor axis was 34.8°. Due to its rotation around the rotor and its pitching in the opposite direction, the maximum nose‐up pitch angle of the downstream blade was 38.6°. The obtained rotor thrust and power curves and the flow visualization around the rotor confirmed the validity of the CFD toolkit.

Simulation of soil cutting blade wear

The results of a laboratory study of the wear patterns of blades of tillage parts are presented. To substantiate the model of soil-cutting blade wear in laboratory studies. Applied installation, providing rectilinear movement of the sample, one-time interaction of the blade with the particles of abrasive mass, and reproducing chip separation, inherent in most loamy soils. The dependence of the angle of inclination of the occipital chamfer to the bottom of the furrow, the width of the occipital chamfer and blade wear along the length of the sample from the cutting path, taken in studies for the main parameters of wear, were obtained. It was found that with increasing depth of cut, the intensity of wear increases, but when there are irregularities and undulations of the bottom of the furrow, it decreases due to the increase in the cutting path with lower loads due to the alternation of depressions and protrusions at the bottom of the furrow. With increasing hardness of the abrasive mass, the intensity of wear of the blade increases, at the same time the value of the stabilized angle of the occipital chamfer to the bottom of the furrow decreases, due to changes in the wear mechanism. With increasing cutting speed, the intensity of blade wear increases due to increased soil resistance forces and specifi c energy expended on its deformation and destruction. It was shown that the abrasive model of the soil corresponds to the real loamy soil for the study of wear of cutting elements. The expansion of the characteristics of the soil model peculiar to "nature" is due to the inclusion of additional components, in particular ceresin and vaseline, in the composition of the base "paraffin + quartz particles".

Effect of Einasto spike and isothermal dark matter density profile on the geometry of wormhole in [formula omitted] gravity

In the present article, we uncover striking properties of traversable wormhole solutions generated under a newly developed f(ℜ,Lm) gravitational theory. Two distinct dark matter density profiles—the Einasto spike and the Pseudo-isothermal model—are employed to demonstrate the existence of stable wormhole geometries with throat radii of 1.18 km and 1.41 km, respectively. Through a rigorous analytical and plot-based survey, we delve deeper into the exotic matter characteristics of these wormhole structures and analyze their matter content in the context of energy conditions. Impressively, both wormhole models exhibit an adiabatic index greater than 1.34 (Γ>43), indicating their inherent stability. What is more, our study of the anisotropy parameter reveals the attractive nature of these wormhole solutions, a crucial property for their potential traversability. This novel work not only broadens our understanding of modified gravity theories but also highlights the remarkable possibilities of traversable wormholes, opening up new avenues in theoretical physics and in the exploration of exotic spacetime geometries.

Pressure-induced lead-free halide double perovskite [formula omitted] for optoelectronic applications

The structural, electronic, optical, mechanical and thermodynamic properties of the lead free double perovskites Rb2CuSbX6(X=Cl,Br) were investigated using first principles based on density functional theory (DFT) under pressure. Our calculated results are in good agreement with other experimental results. Electronic and optical features are pressure dependent, including dielectric effect, pressure-dependent refractive index changes, strong UV reflectivity, suggesting potential applications in solar heating reduction. Using the Voigt-Reuss-Hill approximation, an increase in stiffness, of Rb2CuSbX6(X=Cl,Br) is observed with increasing loads, revealing its stability, making it appropriate for shaping. By analyzing the formation energy and Born's stability criteria, we justified the stability to check the mechanical and thermodynamic stability of the material. In addition, the mechanical properties of Rb2CuSbX6(X=Cl,Br) conducted with the study of elastic constants, elastic moduli, machinibility index, Kleinmen parameter and Vickers hardness. Our investigation indicates that both the materials provide significant potential for very high-quality optical data using optoelectronic applications.

Dynamical model for dog clutch shiftability

AbstractThe dog clutch offers advantages in mass and efficiency, but faces challenges in mismatch speed synchronization, which affects its shiftability. Face impact between dog teeth also reduces its lifespan. Our previous work introduced the kinematical shiftability condition that ensures impact-free gearshift but had limitations due to analysis assumptions. This study eliminates those assumptions, but uses a similar approach. Based on our previous work for dog clutch engagement dynamics, we develop the dynamical shiftability condition. Validation with full dog clutch dynamics showed an agreement. Employing another previous work that introduced shiftability map and parametric study method, we study system parameters impact on shiftability but based on the dynamical shiftability condition.

A meta-analysis of photosynthetic efficiency and stress mitigation by melatonin in enhancing wheat tolerance

BackgroundOur meta-analysis examines the effects of melatonin on wheat under varying abiotic stress conditions, focusing on photosynthetic parameters, chlorophyll fluorescence, leaf water status, and photosynthetic pigments. We initially collected 177 publications addressing the impact of melatonin on wheat. After meticulous screening, 31 published studies were selected, encompassing 170 observations on photosynthetic parameters, 73 on chlorophyll fluorescence, 65 on leaf water status, 240 on photosynthetic pigments.ResultsThe analysis revealed significant heterogeneity across studies (I² > 99.90%) for the aforementioned parameters and evidence of publication bias, emphasizing the complex interaction between melatonin application and plant physiological responses. Melatonin enhanced the overall response ratio (lnRR) for photosynthetic rates, stomatal conductance, transpiration rates, and fluorescence yields by 20.49, 22.39, 30.96, and 1.09%, respectively, compared to the control (no melatonin). The most notable effects were under controlled environmental conditions. Moreover, melatonin significantly improved leaf water content and reduced water potential, particularly under hydroponic conditions and varied abiotic stresses, highlighting its role in mitigating water stress. The analysis also revealed increases in chlorophyll pigments with soil drenching and foliar spray, and these were considered the effective application methods. Furthermore, melatonin influenced chlorophyll SPAD and intercellular CO2 concentrations, suggesting its capacity to optimize photosynthetic efficiency.ConclusionsThis synthesis of meta-analysis confirms that melatonin significantly enhances wheat’s resilience to abiotic stress by improving photosynthetic parameters, chlorophyll fluorescence, leaf water status, and photosynthetic pigments. Despite observed heterogeneity and publication bias, the consistent beneficial effects of melatonin, particularly under controlled conditions with specific application methods e.g. soil drenching and foliar spray, demonstrate its utility as a plant growth regulator for stress management. These findings encourage focused research and application strategies to maximize the benefits of melatonin in wheat farming, and thus contributing to sustainable agricultural practices.

Numerical Simulation Study of the Optimal Parameters for Dust Reduction by an External Air Curtain (EAC) in Continuous Mining Tunnel

Numerical Simulation Study of the Optimal Parameters for Dust Reduction by an External Air Curtain (EAC) in Continuous Mining Tunnel

Parametric AC Loss Study on 7 MW Fully Superconducting Direct-Drive Wind Turbine Generators With Concentrated Stator Winding

Parametric AC Loss Study on 7 MW Fully Superconducting Direct-Drive Wind Turbine Generators With Concentrated Stator Winding

Developing machine learning models with metaheuristic algorithms for droplet size prediction in a microfluidic microchannel

Droplet-based microfluidics holds promise for advanced biomedical applications due to its enhanced accuracy, throughput, rapid reaction time, and minimal reagent consumption. However, achieving droplets with the desired radius often entails costly design iterations. In this paper, we propose a novel approach that combines machine learning algorithms with metaheuristic algorithms to leverage their respective strengths in speed and accuracy. Specifically, we demonstrate the effectiveness of the Rain Optimization Algorithm (ROA) in enhancing the accuracy of five machine learning models. Additionally, we introduce a hybrid model, optimized by ROA, for predicting droplet generation in a cross-junction microfluidic channel, achieving a coefficient of determination (R2) of 0.937, reflecting a 3.6 % increase in accuracy. We employ symbolic regression to validate the hybrid model, yielding an R2 value of 0.987, indicating strong agreement with real data. Furthermore, we utilize the SHAP method in Explainable AI to interpret the hybrid model's performance. Notably, the proposed hybrid model requires only four seconds to solve the prediction problem, significantly reducing computational time compared to the numerical model and experimental method. This approach facilitates the study of each input parameter's impact on droplet size prediction, offering otherwise challenging and costly insights to obtain experimentally.

Effect of the addition of graphite and graphene oxide in the mechanical properties and adsorption of CO2 in cementitious filaments

The study evaluated various aspects of cementitious filaments incorporating graphite and graphene oxide in different proportions (0.01 %, 0.03 %, and 0.06 %) and their effects on physical–chemical properties, mechanical strength, extrudability, constructability, and CO2 adsorption. The findings indicate that adding nanomaterials did not hinder filament extrudability, and all variations were successfully extruded. Regarding constructability, filaments with graphene oxide supported up to the third layer, while those with graphite supported up to the fourth layer. The flexion traction test showed that filaments with 0.01 % and 0.03 % graphite and 0.01 % graphene oxide exhibited superior performance. In axial compression tests, filaments with graphene oxide outperformed the reference mortar. Moreover, mortars with added graphite and graphene oxide displayed better CO2 absorption compared to standard mortar, with an optimized composition identified for this parameter. Specifically, the sample with 0.1 % graphene oxide increased CO2 adsorption by approximately 2.5 % by mass. The study demonstrates the feasibility of incorporating nanomaterials, namely graphite and graphene oxide, into cementitious filaments for additive manufacturing, resulting in enhanced mechanical properties, constructability, and CO2 adsorption. The overall optimized composition, determined via the desirability function, featured cement filament supplemented with 0.03 % graphite (sample 0.03G), achieving 70.55 % optimization in this study's parameters.

A Parametric Study of a SOA Based COEO for Phase Noise Performance and Reliable Operation

A Parametric Study of a SOA Based COEO for Phase Noise Performance and Reliable Operation

Magnetically driven winds from accretion disks in post-asymptotic giant branch binaries

Context. Jets are commonly detected in post-asymptotic giant branch (post-AGB) binaries and originate from an accretion process onto the companion of the post-AGB primary. These jets are revealed by high-resolution spectral time series. Aims. This paper is part of a series. In this work, we move away from our previous parametric modelling and include a self-similar wind model that allows the physical properties of post-AGB binaries to be characterised. This model describes magnetically driven jets from a thin accretion disk threaded by a large-scale, near equipartition vertical field. Methods. We expanded our methodology in order to simulate the high-resolution dynamic spectra coming from the obscuration of the primary by the jets launched by the companion. We present the framework to exploit the self-similar jet models for post-AGB binaries. We performed a parameter study to investigate the impact of different parameters (inclination, accretion rate, inner and outer launching radius) on the synthetic spectra. Results. We successfully included the physical jet models into our framework. The synthetic spectra have a very similar orbital phase coverage and absorption strengths as the observational data. The magnetohydrodynamic (MHD) jet models provide a good representation of the actual jet creation process in these evolved binaries. Challenges remain, however, as the needed high-accretion rate would induce accretion disks that are too hot in comparison to the data. Moreover, the rotational signature of the models is not detected in the observations. In future research, we will explore models with a higher disk ejection efficiency and even lower magnetisation in order to solve some of the remaining discrepancies between the observed and synthetic dynamic spectra.

Enhancing Structural Resilience: Exploring the Novel Sleeve Method for Steel T-Stub Connections

A new sleeve device has been introduced with the aim of enhancing the performance of steel structures under extreme loading conditions. Previous research has primarily focused on numerical simulations of this sleeve's application, emphasizing the need for further investigation to validate its effectiveness. This research paper presents a numerical analysis that explores how the sleeve device influences the deformation capacity and strength of a bolt up to the point of failure. The study involved the use of a T-stub connection with multiple sleeves, each featuring different geometric parameters. To assess the impact on strength and deformation capacity, a comparison was drawn between these findings and the behavior of a T-stub bolted connection without using the sleeve. In addition, Finite Element (FE) models were employed for additional parametric studies. The test outcomes demonstrated a substantial increase in the deformability of the bolted connection when utilizing the sleeve device, all the while preserving the strength and initial stiffness of the bolts. This proposed sleeve method in the study significantly enhances the connection's capacity by delaying bolt failure.

Waste management and salt recovery from solid residue of tannery common effluent treatment plant

ABSTRACT The considerable amount of solid residue generated by the common effluent treatment plant (CETP) of tanneries needs adequate treatment and reclamation before ending up in the environment as solid waste. A sustainable process aiming at tannery CETP waste minimisation and its reuse for sodium chloride salt recovery is presented. The integrated approach consists of dissolution, decolorisation, filtration, evaporation, and crystallization as unit operations. Lab-scale parametric studies have been undertaken to investigate the effects of various parameters at different process stages on product (sodium chloride) yield and quality. The developed process resulted in the recovery of 93% NaCl, having a purity of ∼98.5%. The optimised operating conditions were tested on a bench-scale system (15 kg batch scale of solid residue) deploying solar energy for evaporation-crystallization, and process feasibility was established. An economic analysis was performed, and the techno-economic feasibility was demonstrated to produce 15,733 tons per annum (TPA) of NaCl from 20,000 TPA of solid residue. The techno-economic analysis favours the treatment of tannery CETP waste with the method specified. The proposed scheme can tackle waste management and reuse the recovered product in the tanning process.

A comprehensive parametric study and multi-objective optimization of turbulent jet array impingement for uniform cooling of gas turbine blades with minimized compression power

In the present paper, a comprehensive parametric study and multi-objective optimizations on jet array impingement cooling are conducted for mid-chord sections of gas turbine blades to maximize the heat transfer uniformity on the target plate and minimize the air compression power consumption at different desired Nusselt numbers. The validated numerical method based on RANS equations is utilized to determine the effects of Reynolds number (2500≤Re≤35000), jet spacings (3≤Px,Py≤8), and the jet-to-target distance (0.75≤Pz≤3) on air compression power (Wc), average Nusselt number (Nu‾), and heat transfer uniformity index (UI). According to the parametric study, the increase of Re improves Nu‾ and UI, while intensively increasing Wc. The effect of jet-to-target distance is a function of jet spacings; with the increase of Pz at low jet spacings, Wc,Nu‾, and UI are reduced. Although, at large spacings, Nu‾ and UI increase with Pz, and Wc is independent of Pz. Additionally, the increase of Px decreases Wc, Nu‾, and UI. Increasing Py reduces Nu‾ and Wc. But at small Px and Pz, the UI is descending; while at large Px and Pz, the UI tends to ascend. Three high-accuracy surrogate models are developed using backpropagation artificial neural networks (ANN) for estimating Wc, Nu‾, and UI for input design variables. Sobol global sensitivity analysis is also performed based on the developed models for quantifying the influence of design variables and their interactions on objective functions. As expected, the results indicate that Wc and Nu‾ are the most sensitive to Re, and UI is mainly affected by Px, whereas Py is more affecting the uniformity index rather than compression power. Finally, to find out the best design and flow conditions, optimizations are conducted by the NSGA-II algorithm. The optimal Pareto frontier and final decided solutions by TOPSIS and LINMAP methods are then demonstrated for the desired Nusselt number (NuD) of 70. The TOPSIS method indicates Px=4.70, Py=3.25, Pz=1.40, and Re = 13800 as the best compromise for optimization. The analysis of Pareto solutions in the range of NuD from 35 to 130 suggests a variety of optimal flow and geometrical arrangements for a trade-off between objective functions; therefore, at most, 50% less compression power or 5% more uniformity is approachable corresponding to the design requirements.