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An experimental investigation of the flow control of a circular cylinder in near wake with parallel plates at Re=7500
No full textThe vortex street suppression in the near wake region of the cylinder with parallel plates was investigated using particle image velocimetry (PIV) at Reynolds number of Re = 7500. The rigid plates are designed as flat, parallel with the free-stream direction, and located on both sides of the cylinder. Two different plate lengths (0.5D and 1D based on the cylinder diameter, D) were examined at gap ratios of g/D = 0.1, 0.3, 0.5, 0.7, and 0.9, respectively. Proper Orthogonal Decomposition (POD) analyses were also employed to reveal vortex mechanism in the near wake region. The gap ratio significantly influences the interaction of the vortices. At low gap ratios, the plates directly affect the development of shear layers on both side of the cylinder. The shear layers elongate downstream with a reduction of the vortex shedding frequency. Moreover, Reynolds shear stress, vortex shed-ding instabilities and vortex street are suppressed in the near wake region with the help of using parallel plates. On the other hand, vortex shedding reinforces instabilities at higher gap ratios. Besides, the most effective gap ratio is different for each the plate lengths to suppress instabilities
Opportunities for the Recovery of Rare Earth Elements from Mining Tailings and Urban Mining
No full textThe use of Rare earth element(s) (REE) in high technology in the world is becoming more and more important day by day. This importance has caused REEs used in high technology to be declared in the critical raw material lists of many countries or country groups, especially the European Union (EU), and their criticality and strategic level have increased. The EU is dependent on many countries around the world for REE supplies. Due to their use of high technology, this dependence will continue for decades. Taking this into consideration, the EU has given great importance to the recovery of these REEs in recent years. However, the recovery of these REEs from mining and industrial tailings/wastes is not sufficient for the annual REE needs of these countries. At this point, the recovery of REEs in abandoned mine deposits, which contain high amounts of REEs in many mine residues, attracts the attention of countries using high technology in terms of REE supply. In this regard, studies that determine the amounts and grade characteristics and feasible methods of REEs that can be recovered from mine tailings can contribute to reducing the REE supply risk. Thus, these new findings will be able to contribute to the REE supply of many countries, especially EU countries that produce high technology. In this study, recovery opportunities of REEs from mining residues and urban wastes were evaluated. An attempt has been made to clarify the issue of REE recovery from urban waste in the world and to find an answer to the question of whether REE can be supplied without opening a mining operation. In addition, this study reviewed the literature on the environmentally responsible management of WEEE for recycling. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024
Improvement in electrical properties of Bi-2212 superconducting materials substituted with large-scale nano-sized tin
No full textIn the current work, the effect of nano-sized Sn (50 nm)/Sr partial replacement on the superconducting properties such as crystal structure, quality of intra- and intergrain boundary coupling, dc electrical resistivity, and dc magnetization in the Bi-2212 ceramic superconductors were investigated. Ceramic superconductors with nominal composition of Bi2Sr2-x(Sn)(x)Ca1Cu1.75Na0.25Oy where x = 0.25, 0.30, 0.35 and 0.40 were prepared by solid-state reaction method and characterized by powder X-ray diffraction (XRD), dc electrical resistivity, scanning electron microscopy (SEM) and magnetic hysteresis (M-H) measurements. Phase examination of by XRD indicated that the doping of x = 0.25 ratio nano-sized SnO2 to the strontium sites improved the formation of the Bi-2212 high-temperature superconducting phase. SEM micrographs showed that the morphological structure of all samples consisted of plate-like grains, which were separated from each other by grain boundaries, indicating the Bi-2212 superconducting phase. The highest superconductivity transition temperature among the samples was measured as the T-c(onset) = 86 K at x = 0.25 in Bi2Sr2-x(Sn)(x)Ca1Cu1.75Na0.25Oy. M-H loops of the Bi2Sr2-x(Sn)(x)Ca1Cu1.75Na0.25Oy sample at x = 0.25 ratio is larger compared to other examples, indicating improvement intergrain connectivity as well as enhanced flux pinning centers. In addition, the critical current (J(c)) values of the samples were calculated from M-H measurement using Bean's critical current model. The best J(c) values were obtained as 570 A/cm(2) at 15 K, which is a relatively high value for BSCCO superconductors with polycrystalline structure.Scientific and Technological Research Council of Turkiye (TUBITAK)Open access funding provided by the Scientific and Technological Research Council of Turkiye (TUBITAK)
Effect of Permeability and Length of a Perforated Splitter Plate Downstream of the Circular Cylinder
No full textExtensive research has been conducted on the flow control of bluff bodies to address negative impacts such as vibration, acoustic noise, and resonance caused by wake flow. The circular cylinder, due to its simple geometry, is frequently studied as a bluff body and is utilized in various engineering applications including cooling system pipes, electrical pylons, industrial flue systems, overpasses, satellite antennas, electrical cables, and marine drilling platforms. In this investigation, a perforated splitter plate was strategically positioned at different downstream locations to manage the wake flow of the cylinder. The experiments were conducted in a sophisticated, closed-loop water channel at the Fluid Mechanics Laboratory of Cukurova University, providing a controlled environment for precise flow analysis. To measure the instantaneous velocity vector field in the wake region of the cylinder at a Reynolds number (Re) of 5000 (based on the cylinder diameter, D), particle image velocimetry (PIV) was employed. Three different permeability values for the splitter plate (e=0.30, 0.50, 0.70) and three lengths (ls*=1, ls*=2, ls*=3) were tested, maintaining a constant gap (G/D=1) between the splitter plate’s leading edge and the cylinder surface. The splitter plates were aligned with the flow direction (?=0°). The permeable separator plates minimize the interaction of boundary layers formed around the cylinder, enhancing their effect in downstream regions where shear layer interaction is more pronounced. Consequently, this results in reduced fluctuations and a more stabilized wake flow downstream of the cylinder. © (2024), (Isfahan University of Technology). All rights reserved
IfNot: An approach towards mitigating interest flooding attacks in Named Data Networking of Things
No full textNamed Data Networking (NDN) has emerged as a model to accommodate content distribution, security, and mobility. Recently, NDN has been applied to the Internet of Things (IoT), referred to as Named Data Networking of Things (NDNoT). In the rapidly evolving landscape of the NDNoT securing data transmission is paramount. The main purpose and contribution of the research presented in this paper is to safeguard the security vulnerabilities of data transmission in NDNoT. This paper specifically addresses the critical issue of interest flooding attacks in NDNoT. These attacks can disrupt network operations posing far-reaching threats to data integrity and availability. To mitigate these attacks and threats the paper introduces the IfNoT mechanism and evaluates its performance through comprehensive simulations in a realistic and recognized simulator, called Cooja. IfNot identifies the potential interest flooding attacker nodes in the NDNoT environment. It reduces the impact of the attack and the undesirable interest traffic caused by such an attack, which optimizes the network resource utilization at a maximum level. The study also explores the influence of key parameters provided by the IfNoT mechanism. Moreover, the study also identifies optimum settings for these parameters to enhance network utilization. When evaluated using various metrics, including success rate, average latency, and total interest traffic, under different conditions and parameter settings, IfNoT was able to counter the interest flooding attacks effectively. IfNoT mechanism is able to increase success ratio up to 28%, decrease average latency up to 31%, and decrease total interest traffic up to 58%.AVATAR project - Scientific and Technological Research Council of Turkey (TUBITAK) [116E227]This work was supported by the AVATAR project funded by the Scientific and Technological Research Council of Turkey (TUBITAK) [grant number 116E227]
Effect of recycled polyethylene catalyst for Mediterranean pine seed shell biomass pyrolysis on hydrogen and methane production
No full textThe present study exhibits the potential of hydrogen and methane gases production from the Mediterranean pine tree seed shell biomass over recycled polyethylene wastes as catalyst. In the study, firstly, the viscosity and density of polyethylene materials and degassing point were determined. The pyrolysis was carried out at a rate of 50 degrees C/min at 600 degrees C temperature. The obtained gases were analyzed with gas chromatography device. At the last step of the experiments, solid residues were observed under an optical microscope, and their microstructures were also examined. The results showed that Mediterranean pine seed shell biomass and its mixture with low-density polyethylene may produce methane and hydrogen gases. M8 catalyst, which has one of the lowest viscosity values (0.45 gr/10 min.) and highest density values (0.950 gr/cm3) produced the highest methane and hydrogen gas yields. In the pyrolysis experiments, 38.44% CH4, 19.50% CO2 and 42.06% H2 gases were obtained from Mediterranean pine seed shell biomass. Moreover, CO2 emission values of biomass were calculated and compared with DEFRA values. The study demonstrated that, since hydrogen and methane can be obtained through the pyrolysis process, Mediterranean pine tree seed shell can be classified as a new biomass source and has potential to alternative fuel to fossil-based fuels for internal combustion engines
Biomarkers From Discovery to Clinical Application: In Silico Pre-Clinical Validation Approach in the Face of Lung Cancer
No full textBackground: Clinical biomarkers, allow better classification of patients according to their disease risk, prognosis, and/or response to treatment. Although affordable omics-based approaches have paved the way for quicker identification of putative biomarkers, validation of biomarkers is necessary for translation of discoveries into clinical application.Objective: Accordingly, in this study, we emphasize the potential of in silico approaches and have proposed and applied 3 novel sequential in silico pre-clinical validation steps to better identify the biomarkers that are truly desirable for clinical investment.Design: As protein biomarkers are becoming increasingly important in the clinic alongside other molecular biomarkers and lung cancer is the most common cause of cancer-related deaths, we used protein biomarkers for lung cancer as an illustrative example to apply our in silico pre-clinical validation approach.Methods: We collected the reported protein biomarkers for 3 cases (lung adenocarcinoma-LUAD, squamous cell carcinoma-LUSC, and unspecified lung cancer) and evaluated whether the protein biomarkers have cancer altering properties (i.e., act as tumor suppressors or oncoproteins and represent cancer hallmarks), are expressed in body fluids, and can be targeted by FDA-approved drugs.Results: We collected 3008 protein biomarkers for lung cancer, 1189 for LUAD, and 182 for LUSC. Of these protein biomarkers for lung cancer, LUAD, and LUSC, only 28, 25, and 6 protein biomarkers passed the 3 in silico pre-clinical validation steps examined, and of these, only 5 and 2 biomarkers were specific for lung cancer and LUAD, respectively.Conclusion: In this study, we applied our in silico pre-clinical validation approach the protein biomarkers for lung cancer cases. However, this approach can be applied and adapted to all cancer biomarkers. We believe that this approach will greatly facilitate the transition of cancer biomarkers into the clinical phase and offers great potential for future biomarker research. Biomarkers, which are routinely used in clinics, allow better classification of patients according to their disease risk, prognosis, and/or response to treatment. Although affordable omics-based approaches have paved the way for quicker identification of putative biomarkers, validation of biomarkers is necessary for translation of discoveries into clinical application. This research article highlights the challenges of translating cancer biomarkers into clinical practice and summarizes feasible step toward in silico pre-clinical validation using the example of lung cancer types. Accordingly, protein biomarkers proposed for lung cancer are being investigated using the in silico pre-clinical validation approach to determine whether they have cancer altering properties (i.e., oncoprotein, tumor suppressor, and cancer hallmark), are expressed in body fluids (i.e., plasma/serum, saliva, urine, and bronchoalveolar lavage) and can be targeted with FDA-approved drugs. We believe that the step of in silico pre-clinical validation is the future of biomarker research for all professionals involved in clinical, biological, epidemiological, biostatistical and health research, and that it will greatly facilitate the transition of biomarkers to the clinical phase.Not applicable
Antimicrobial topical polymeric films loaded with Acetyl-11-keto-?-boswellic acid (AKBA), boswellic acid and silver nanoparticles: Optimization, characterization, and biological activity
No full textThe study examined the antimicrobial and antioxidant potential of pure Acetyl-11-keto-beta-boswellic acid (AKBA), boswellic acid (70%) and AKBA loaded nanoparticles as topical polymeric films. The optimized concentration (0.05 % w/v) of pure AKBA, boswellic acid (BA), and AKBA loaded silver nanoparticles were used to study its impact on film characteristics. Carboxymethyl cellulose (CMC), sodium alginate (SA), and gelatin (Ge) composite films were prepared in this study. The polymeric films were evaluated for their biological (antioxidant and antimicrobial activities) and mechanical characteristics such as tensile strength (TS) and elongation (%). Moreover, other parameters including water barrier properties and color attributes of the film were also evaluated. Furthermore, assessments were conducted using analytical techniques like FTIR, XRD, and SEM. Surface analysis revealed that AgNP precipitation led to a few particles in the film structure. Overall, the results indicate a relatively consistent microstructure. Moreover, due to the addition of AKBA, BA, and AgNPs, a significant decrease in TS, moisture content, water solubility, and water vapor permeation was observed. The films transparency also showed a decreasing trend, and the color analysis revealed decreasing yellowness (b*) of the films. Importantly, a significant increase in antioxidant activity against DPPH free radicals and ABTS cations was observed in the CSG films. Additionally, the AgNP-AKBA loaded films displayed significant antifungal activity against C. albicans. Moreover, the molecular docking analysis revealed the inter-molecular interactions between the AKBA, AgNPs, and composite films. The docking results indicate good binding of AKBA and silver nanoparticles with gelatin and carboxymethyl cellulosemolecules. In conclusion, these polymeric films have potential as novel materials with significant antioxidant and antifungal activities.TRC grant [BFP/RGP/HSS/22/007]The study was supported by TRC grant number BFP/RGP/HSS/22/007
Dynamic analysis of viscoelastic porous functionally graded plates resting on elastic foundation
No full textIn this study, free and forced vibration behaviour of viscoelastic porous functionally graded (VPFG) plates resting on elastic foundations are investigated. Differential equations are obtained via higher order shear deformation theory. Equations of motion are obtained through energy formulations and Hamilton's principle. Navier's method based on double Fourier series is employed for the solution. Damping effect is implemented into the analysis by means of Kelvin and linear standard viscoelastic models. Viscoelastic material properties are used instead of elastic properties by means of the correspondence principle. Displacements of the plates are determined in Laplace domain and transformed into time domain by using Durbin's Modified Inverse Laplace transform method. The proposed algorithm's accuracy is validated through free and damped vibration analyses on VPFG plate, with results compared to existing studies in the literature. The study examines the influence of viscoelastic damping parameters, porosity volume fraction indexes, foundation characteristics, porosity distribution patterns and material property variations on the damped forced vibration response
Suo?avanje s izazovima u vezi s ocjenjivanjem zelene gradnje prema LEED-u u Turskoj
No full textThis study examined the effectiveness of the LEED green building rating system and identified performance gaps in developing countries using Türkiye as a case study. The analysis of 134 LEED Platinum V4-certified buildings in Turkiye revealed discrepancies in high-priority sites, site evaluation, building product definition and optimisation, and low-emission material credits compared with other countries. Variations in energy, atmosphere, and indoor environmental quality criteria were also noted within LEED Platinum-certified buildings in Turkiye. The study concludes that while LEED is widely embraced, local standards and contextual factors must be considered when implementing these programs. © 2024, Croatian Association of Civil Engineers. All rights reserved